This Article Extract Full Text (PDF) Free Letters to the Editor: Submit a response Alert me when this article is cited Alert me when Letters to the Editor are posted Alert me if a correction is posted Services E-mail this article to a friend Similar articles in this journal Alert me to new issues of the journal Add to My File Cabinet Download to citation manager Rights and Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by HADDAD, F. S. Articles by DUNCAN, C. P. Search for Related Content PubMed Articles by HADDAD, F. S. Articles by DUNCAN, C. P. Social Bookmarking                   What's this?

Instructional Course Lectures, The American Academy of Orthopaedic Surgeons - Femoral Bone Loss in Total Hip Arthroplasty: Classification and Preoperative Planning*

FARES S. HADDAD, B.SC., M.CH.(ORTH), F.R.C.S.(ORTH), BASSAM A. MASRI, M.D., F.R.C.S.(C), DONALD S. GARBUZ, M.D., F.R.C.S.(C) and CLIVE P. DUNCAN, M.D., F.R.C.S.(C), VANCOUVER, BRITISH COLUMBIA, CANADA

An Instructional Course Lecture, American Academy of Orthopaedic Surgeons

	Introduction

Top Introduction General Considerations Patient-Related Factors Factors Related to the... Templates for Planning of... Operative Approach Operative Plan Classification Systems Assessment of the Classification... Overview References

 
Despite the excellent results of total hip arthroplasty, the number of patients who need a revision operation is increasing. Moreover, reconstructive surgeons now are faced with complex primary cases for which a total hip arthroplasty may not have been considered in the past, such as hips with a previous arthrodesis or severe dysplasia^{3,9,33,40,58,66}. These arthroplasties present many challenges, foremost of which is the management of bone abnormalities and of bone loss in particular. Therefore, the preoperative evaluation and description of bone deficits are of great importance.

A number of investigators have produced systems for classification of bone loss about the hip^48,49. These systems have been devised in order to quantify the severity of femoral bone loss, to explain the indications for particular revision arthroplasty techniques, and to assess the results of these interventions^8,55. Many of these classification systems are similar in principle, yet are described differently. Without a unified classification system that has been proved to be reliable, valid, user-friendly, and widely accepted, it is exceedingly difficult to compare the various reconstructive techniques that are currently available. Such a system should help to guide the surgeon to the best treatment option for the deficit that is encountered. It also should help the surgeon to determine the appropriate approach, the implants that should be available, and the type of bone graft that may be needed.

In this review, the preoperative evaluation of femoral bone loss after total hip arthroplasty is summarized and the most commonly used classification systems are described.

	General Considerations

Top Introduction General Considerations Patient-Related Factors Factors Related to the... Templates for Planning of... Operative Approach Operative Plan Classification Systems Assessment of the Classification... Overview References

 
Before attempting to revise a hip replacement that has associated bone loss, the surgeon should have a complete and logical preoperative plan. Many factors have to be considered, such as the general health of the patient, potential techniques for the removal of the existing implants, and strategies for achieving a durable, stable reconstruction. The ultimate aim must be to ensure satisfactory femoral fixation while simultaneously restoring the biomechanics of the hip and reconstituting the femoral bone stock to some degree whenever possible. The reconstructive plan should include the exposure and removal of the implants, treatment of the bone loss, and the final reconstruction with consideration given to the type, site, and stability of the components (Table I).

	Patient-Related Factors

Top Introduction General Considerations Patient-Related Factors Factors Related to the... Templates for Planning of... Operative Approach Operative Plan Classification Systems Assessment of the Classification... Overview References

 
Before a revision total hip arthroplasty is done, it is mandatory to obtain a full history and to perform a physical examination as well as a thorough radiographic assessment. Many factors have to be considered, such as the general health of the patient, especially if he or she is frail and elderly. Most patients who need a revision arthroplasty are approximately a decade older than they were at the time of the primary operation. Consequently, the health and physiological reserve of these patients are often reduced. The patient's fitness for the operation should be included in a risk-benefit equation that takes into account the fact that the revision will be more lengthy and complicated than the primary procedure was.

Assessment of the general health of a patient also includes his or her fitness for postoperative rehabilitation. The gait may be influenced by the hip disability, but a patient's balance and the function of the upper limbs will assume increased relevance after a revision operation if it is necessary to relieve the load on the hip. The patients often need a prolonged period of convalescence. Specific concerns encountered in the revision scenario are the ability of a patient to comply with limited weight-bearing and to control a hip replacement that is more likely to dislocate than was the primary replacement⁵³. Postoperative instability, therefore, should be a concern even if it was not part of the failure mechanism that led to the revision.

	Factors Related to the Hip

Top Introduction General Considerations Patient-Related Factors Factors Related to the... Templates for Planning of... Operative Approach Operative Plan Classification Systems Assessment of the Classification... Overview References

 
The findings on clinical examination of the hip will influence the reconstruction plan. The previous skin incision or incisions suggest which approach or approaches have been used, and, whenever possible, an extensile approach should be considered⁵⁰. In most patients, a direct lateral approach to the hip may not provide adequate exposure and should not be used, even if it was the initial approach for the primary procedure. Instead, a posterior approach through previously uninvolved tissue provides better exposure, and the approach can be extended if a trochanteric osteotomy, a trochanteric slide, or an extended femoral osteotomy is necessary. Details of previous approaches to the hip joint must be supplemented by a clinical assessment of abductor function. A careful examination of the soft tissues is also warranted as scarring and stiffness may render the approach and exposure difficult, may increase the likelihood of fracture during dislocation or manipulation, and may influence the risk of injury to the sciatic nerve.

An evaluation of the range of motion of the hip is frequently omitted in the presence of a painful or unstable prosthetic hip, but the range of motion is an important indicator of heterotopic ossification, extracapsular contracture, or potential impingement. A hip with very limited movement is often difficult to expose unless an extensive capsular release is performed and an extensile approach is used⁵⁰. In such patients, great care needs to be taken intraoperatively so as not to cause a fracture at the site of femoral bone loss. Intraoperative lengthening of a limb in the presence of a stiff hip may also prove to be very difficult unless extensive releases are performed.

Documentation of the neurovascular status of the extremity is required because of the increased prevalence of nerve palsies after revision hip arthroplasty. The prevalence of sciatic nerve palsy after primary hip arthroplasty has been reported to range from approximately 0.6 percent (in series of 600 to more than 2000 patients)⁴³ to 1.3 percent (twenty-one of 1661)⁶⁰, but it is approximately three times more frequent after revision hip arthroplasty^43,60. Vascular injury to the limb, although rare, is also more common after revision arthroplasty^2,51,60.

Assessment of Infection
A careful recording of the history and a thorough physical examination of the patient should precede any tests for the diagnosis of infection. A high index of suspicion is essential. The patient should be carefully questioned with regard to any wound-healing complications, early infections, or prolonged administration of antibiotics after a previous operation. Delays in discharge from the hospital also suggest a notable early complication. Questions about recent infections, such as a skin infection or ulceration, a urinary tract infection, or a dental infection, can also be revealing.

The rational use of preoperative investigations in a sequential fashion allows the correct diagnosis of infection in most patients^31,32,63. The initial investigations should be of the erythrocyte sedimentation rate and the level of C-reactive protein. If both tests reveal normal findings and the history and physical examination are not suggestive of infection, no additional tests are necessary⁶³. Aspiration of the hip joint is neither indicated nor recommended in this situation. If either the erythrocyte sedimentation rate or the C-reactive protein level is elevated, additional tests, such as aspiration of the hip joint, are indicated. The aspiration should be performed at least four weeks after the discontinuation of all antibiotic therapy. If a culture of aspirated fluid is negative and the index of suspicion remains high, the aspiration should be repeated, perhaps with the guidance of arthrography or ultrasound. If the findings remain negative and the index of suspicion for infection is still high, ancillary tests, such as a repeat aspiration of the hip joint, cultures of tissue, or a sequential technetium-indium nuclear scan, may be considered⁶³. If all of these tests are negative, the surgeon may resort to tests such as examination of a frozen section of intra-articular tissue at the time of the revision arthroplasty to help to distinguish between aseptic loosening and infection. Evaluation of a frozen section has excellent dependability, with high sensitivity and specificity^44,63. Intraoperative cultures of tissue should be performed for all patients as confirmatory tests.

Radiographic Assessment
Although it is often difficult to truly appreciate the type of bone loss present on the femoral side before the operation, it is of the utmost importance to examine the patient thoroughly before the operation and to define both the location and the severity of bone loss. This examination is facilitated by a complete set of high-quality radiographs. Many centers do not routinely have sufficient inventories of prostheses and allografts to manage a large amount of bone loss; therefore, it is vital to identify these requirements preoperatively.

True anteroposterior and lateral radiographs of the entire femur should be made, as should a true lateral radiograph of the hip. The lateral radiograph is often made as a cross-table radiograph and is frequently disappointing in terms of clarity because the bone details are obscured by the soft-tissue shadows. Use of the methods of Lauenstein and Hickey results in a much superior lateral radiograph of the proximal portion of the femur⁴. The pelvis is rotated 45 degrees toward the affected side. The hip is then abducted and externally rotated so that it comes to lie on the plate that is below the patient. The beam is directed vertically, and the resultant image is a high-quality lateral radiograph of the proximal part of the femur with an iliac oblique view of the acetabulum²⁰. In addition, oblique radiographs may show areas of cortical thinning or bone loss that are not apparent on anteroposterior and lateral radiographs⁸. These areas can be conveniently seen on the Judet radiographs of the pelvis that are commonly made to assess acetabular bone loss.

Additional imaging techniques are occasionally necessary. Cross-sectional imaging modalities have little to offer in the assessment of femoral bone stock in the presence of a failed prosthesis, although computerized tomography may be useful for evaluating bone stock before revision of an excision arthroplasty. Occasionally, a computerized tomography scan of the proximal part of the femur with or without three-dimensional reconstruction provides useful data on discrete osseous deficiencies and helps in the planning for customized implants^5,59. Computerized tomography scans also may be useful in the evaluation of the position of the implants (in particular, the version of the femoral and acetabular components), especially in hips with recurrent instability that may be related to malposition of the components. Three-dimensional computerized tomography scans and foam or plastic models developed on the basis of computerized tomography data are increasingly being used in the preoperative evaluation of distorted femoral anatomy⁶⁹. Magnetic resonance imaging may be useful in the assessment of the extent of radiolucent cement distal to a failed prosthesis that was implanted before the routine addition of radiopaque markers to bone cement²¹.

After the radiographic assessment, the bone loss is classified and the reconstruction is planned.

	Templates for Planning of the Reconstruction

Top Introduction General Considerations Patient-Related Factors Factors Related to the... Templates for Planning of... Operative Approach Operative Plan Classification Systems Assessment of the Classification... Overview References

 
Because of the progressive nature of bone loss secondary to osteolysis, complete up-to-date images should be available to ensure that the plan devised in the clinic is still appropriate. This is particularly true for hips in which the deformity or bone loss is in the sagittal plane. Unless excellent-quality lateral radiographs are made and used to create a template, a deformity in the sagittal plane may be missed and a perforation or fracture may occur at the time of the revision arthroplasty.

A template not only allows the surgeon to determine the approximate size and position of the components^1,7,68, but it also provides a guide to the entire procedure before the surgeon begins to operate. A template should be made on both the anteroposterior and the lateral radiograph on the basis of anatomical landmarks such as the greater and lesser trochanters if these are still present. The precise technique for creating a template depends on the method of fixation chosen, as the goals of fixation with cement, metaphyseal bone ingrowth, diaphyseal bone ingrowth, impaction grafting, and structural allografting are different. In all patients, any area of femoral bone loss should be identified and protected either with strut allograft^15,54 or by prosthetic bypass, which should be a minimum of two cortical diameters beyond the area of weakness⁴². Care also should be taken to ensure that the anterior femoral bow is incorporated into the planning of revisions with use of a long-stem component in order to avoid intraoperative perforations and fractures²².

When a template is made, the planned center of rotation of the hip is based around the existing acetabular component or placed where it will be relative to the revision acetabular component. This center of rotation can then be referenced to the teardrop and compared with that on the contralateral side. If there is a limb-length discrepancy that needs to be accommodated for by the femoral component, the center of rotation of the femoral head can be adjusted by the requisite amount. The template of the femoral component then can be made accurately with regard to the correct length and offset on the basis of this center of rotation. When there is massive bone loss, it is prudent to create templates for a number of options in order of preference so that one or more fallback strategies are available.

Although construction of a preoperative template is an essential component of any revision procedure, it is important to be aware of the limitations of preoperative assessment of bone loss. The systems for the classification of bone loss that are summarized later in the present report describe the intraoperative deficits after removal of the failed components. Frequently, the bone loss that is encountered after removal of the components is considerably more extensive than that suggested by preoperative imaging. The operative plan should, therefore, include a strategy for the management of an unexpectedly large amount of bone loss.

	Operative Approach

Top Introduction General Considerations Patient-Related Factors Factors Related to the... Templates for Planning of... Operative Approach Operative Plan Classification Systems Assessment of the Classification... Overview References

 
A failed hip replacement may be associated with considerable loss of bone stock as a result of osteolysis, component migration, a previous operation, or the effects of stress-shielding of the femur by the implant. The operative exposure must be adequate to allow these areas of bone deficiency to be addressed successfully.

Before performing a revision hip arthroplasty, the surgeon should examine the patient clinically and radiographically to determine whether the operation can be adequately accomplished through one of the standard approaches used in primary hip arthroplasty. If not, an extensile exposure should be considered⁵⁰. If there is any history of instability, the soft tissues should be carefully evaluated and managed in a manner that ensures postoperative stability. The direction of instability should be determined from the history, the radiographs, and the records on any closed reduction of the components. This assessment helps to determine whether preservation of the anterior or posterior soft-tissue envelope is more important during exposure. The abductor muscles of the hip should be carefully protected or repaired, and excessively tight adductor muscles should be released.

In general, anterolateral approaches through the gluteus medius and minimus should be reserved for simple revision operations. These approaches are not extensile, as they cannot be converted to a trochanteric osteotomy without injuring the blood supply of the trochanteric fragment. If a trochanteric osteotomy is likely to be necessary, it should be performed before the anterior two-thirds of the abductors have been unnecessarily detached. For this reason, the posterior approach is more versatile, as it allows ready extension of the exposure to a classic trochanteric osteotomy, a trochanteric slide²⁶, or an extended trochanteric osteotomy⁷¹ if the exposure proves difficult.

In both primary and revision total hip arthroplasty, a number of specialized approaches that allow a safe and wide intraoperative exposure and decrease the risk of femoral fracture during the exposure of the joint or during positioning or removal of the implant have been described⁵⁰. A carefully planned approach avoids excessive devitalization of soft tissue, uncontrolled bone avulsion, and excessive retraction and manipulation, which may lead to periprosthetic fracture or poor positioning and fixation of the implant. The length and exact location of any trochanteric osteotomy should be estimated preoperatively to allow sufficient access and to leave a fragment that remains well vascularized. To this end, it is vital not to strip the trochanteric fragment excessively during the process of freeing up the trochanteric fragment before reattaching it after the trochanteric osteotomy.

We favor the trochanteric slide in most instances in which a trochanteric osteotomy would be considered. This approach affords particularly good access to hips in which there is a close approximation of the proximal part of the femur to the acetabulum, such as those with severe protrusio, or when there is marked preoperative stiffness. The trochanteric slide should be considered for stiff hips with poor femoral bone stock because of the risk of periprosthetic femoral fracture. So-called dynamizing of the hip by advancing the trochanteric fragment, and thereby adding tension to the abductors, can be used to advantage when a large amount (more than two centimeters) of limb-lengthening or shortening is anticipated. Finally, attachment of the abductor mechanism to a proximal femoral allograft is greatly facilitated by this approach.

When a loose cemented femoral component is revised, attention should be paid to the presence of solidly bonded cement that remains in the femoral canal after the prosthesis has been successfully extracted from above. In particular, a long column of cement may remain distal to the position of the original component, especially if an intramedullary cement restrictor was not used at the primary procedure. The need to remove this cement should be determined during preoperative planning and should be based on the presence or absence of infection and the type of revision prosthesis to be used. If removal of solidly fixed cement distal to the original component is considered necessary, then serious consideration should be given to an additional procedure in order to improve visualization of the distal cement, as the risk of damage to the femur is considerable when removal of solid distal cement is attempted from above. Options include creation of simple access holes for better visualization and irrigation, an extended trochanteric osteotomy, bivalving of the femur, and production of a distal cortical window. For example, Sydney and Mallory described the technique of controlled cortical perforation for excision of cement in the course of revision of cemented femoral components⁶⁵. With this technique, multiple perforations are made in the cortex of the femur in order to improve visualization of the femoral canal, inspection of the cement mantle, and irrigation of the canal. The number of perforations depends on the extent of exposure that is required and on the amount of bone cement that needs to be removed. If a distal window is necessary, consideration should be given to the retention of a soft-tissue hinge to maintain the viability of the trapdoor of removed bone. This is particularly important when dealing with a revision for infection at the site of a hip replacement³⁹. Ultrasonic tools also have been developed to aid in the removal of cement. They can be used to distinguish between cement and bone and to remove the cement selectively without perforating the bone. Unless there is cement beyond the anterior bow of the femur, these tools enable the surgeon to remove cement from above without resorting to extensile approaches.

Removal of osseointegrated stems inserted without cement requires a familiarity with the particular stem design. The surgeon should be aware of the extent and location of porous coating or fiber-metal pads, the modularity of the prosthesis, the presence or absence of a collar, and the level at which the metaphyseal flare of the prosthesis joins the more tubular distal part. Some types of stems are best removed with use of metal-cutting equipment to remove a prominent collar or to divide the component at the base of the metaphyseal flare through a small cortical window²⁶. When removing solid stems inserted without cement, we almost always use a trochanteric osteotomy extended down to the distal extent of the porous coating, unless this brings the osteotomy beyond the isthmus, as we find that this reduces the extent of damage to the femoral bone stock. Even when the stem does not appear to be solidly osseointegrated on preoperative radiographs, the extended trochanteric osteotomy can be very useful, as the component is often retained by tenacious fibrous ingrowth.

Stems that have been precoated with methylmethacrylate and are inserted with cement are designed to achieve a very rigid bond with the cement mantle. When solidly fixed, these stems are usually impossible to extract from above as they do not debond from the cement. Removal of a solidly fixed precoated stem usually requires extensive visualization of the cement mantle, which is most conveniently achieved with an extended trochanteric osteotomy.

The use of the extended trochanteric osteotomy in revision total hip arthroplasty facilitates the revision of the femoral component. By virtue of the wide exposure of the femoral canal, cement can be easily removed and the new component can be easily aligned. Cortical perforation, which is common when cement is removed blindly with use of hand and power instruments, is avoided. Furthermore, with the controlled osteotomy, fracture of the weak proximal part of the femur is avoided as well. A deformity in the coronal plane can also be accommodated for by carefully planning the level of the osteotomy so that a straight or bowed stem is inserted distal to the deformity and the proximal-lateral cortical fragment is then reapproximated onto the femur with use of the revision component as a scaffold. One disadvantage of this approach, however, is the decreased hoop strength of the proximal part of the femur. The calcar is at substantial risk of fracture, and soft-tissue tethers should be carefully released so that sudden manipulations do not cause an avulsion fracture. Great care also must be taken when the femur is retracted for the preparation of the acetabulum because the anterior retractor can easily cause a fracture of the medial aspect of the femur. For this reason, we complete the acetabular preparation before the osteotomy whenever possible. Likewise, removal of the femoral cement should be delayed until after the acetabulum has been prepared and, if possible, the component has been inserted, so that the weakened femur is not manipulated excessively. This also reduces the blood loss from the femoral side.

	Operative Plan

Top Introduction General Considerations Patient-Related Factors Factors Related to the... Templates for Planning of... Operative Approach Operative Plan Classification Systems Assessment of the Classification... Overview References

 
A team that is sufficiently experienced to manage the complexity of the procedure is necessary. A detailed preoperative plan should be made to ensure that all of the required equipment, bone graft, staff, and time are available. Great care is necessary, particularly on the part of the assistants, to ensure that excessive manipulation does not lead to a femoral fracture. Access to fluoroscopy or intraoperative radiography may be important to avoid cortical perforation and eccentric reaming of the femur.

The assessment of any limb-length discrepancy and of the need for revision of the acetabular component is essential to the preoperative planning of a femoral reconstruction. If the acetabular component needs to be revised, the subsequent ability to change the position of the center of hip rotation and to choose the size of the femoral head affords more options for the femoral reconstruction. If there is no indication to revise the acetabular component, additional consideration must be given to the potential for a change of the acetabular liner. Review of the initial operative reports is vital to ensure that the correct equipment is available at the time of the operation. It is also important to plan the femoral reconstruction such that the appropriate length, tension, and offset are obtained. Occasionally, it is necessary to revise a well fixed acetabular component in order to achieve an acceptable femoral reconstruction with satisfactory hip biomechanics and no instability.

Every effort should be made to minimize bone loss during removal of the implant. A combination of hand tools, power tools, and ultrasonic tools may be used to remove cement without perforating or fracturing the femur. There is no substitute for meticulous care in the handling of these instruments or for careful preoperative imaging, including both anteroposterior and lateral radiographs, to carefully outline the location and the size of the cement mantle in all three planes. Finally, when substantial forces are anticipated during the extraction of the cement, during the preparation of the medullary canal, or during the final seating of the implant^47,61,64, it is far better to protect the femur with cerclage wire or cable fixation prophylactically or with cortical onlay strut allografting when bone stock is deficient and requires augmentation. This is particularly important in hips in which impaction grafting is used^{14,24,25,34,35}.

In the presence of femoral bone loss, the risk of intraoperative fracture is high^6,56,57. A revision operation is associated with a higher risk of intraoperative fracture than is a primary hip replacement operation^10,62. Scott et al. found that twelve of sixteen intraoperative proximal femoral fractures were associated with a secondary operation⁶². These fractures occurred during dislocation of the hip, extraction of the cement, or reaming through old cement. Egan and Di Cesare also noted a higher rate of eccentric reaming, femoral perforation, and femoral fracture with the use of longer and wider femoral stems and with poor-quality host bone¹³. If a cortical perforation is recognized at the operation, it should be bypassed either with a longer stem or with a cortical onlay allograft strut and fixation with cerclage wire^23,45,52,67.

Femoral bone loss is seen in both primary and revision hip replacement. In the former, it is related to dysplasia, a previous operation or arthrodesis, or a variety of conditions, such as hereditary and metabolic bone diseases, that lead to a deterioration in bone quality. Most cases of severe femoral bone loss, however, are seen in revision procedures. In order to better understand and apply the various reconstructive options that are available on the femoral side, a comprehensive and easy-to-apply classification system is of paramount importance. Such a classification system is also essential for the uniform reporting of the results of these various reconstructive options.

To date, several classification systems have been proposed, but none has received universal acceptance. The emphasis of the different classification systems varies with the objective that each was designed to achieve. A comprehensive system for the classification of femoral bone loss, as it pertains to the various treatment options, was described by Chandler and Penenberg⁸. D'Antonio et al. presented the collaborative efforts of the American Academy of Orthopaedic Surgeons Committee on the Hip to classify femoral bone loss in total hip arthroplasty¹¹. This system encompasses all femoral abnormalities found during both primary and revision hip arthroplasty. Gross et al. described a simple classification system in which the emphasis is on determining the necessity for the use of bone allograft in the reconstruction^27,28. Engh et al.^17-19 and Paprosky et al.⁵⁵ both developed classification systems that revolve around the ability of the femoral diaphysis to support a prosthesis inserted without cement. The Endo-Klinik classification places more emphasis on the ability of the femur to support a prosthesis inserted with cement¹⁶. Different classification systems have also been proposed by Mallory⁴⁶, Johnston et al.³⁶, and Gustilo and Pasternak³⁰.

	Classification Systems

Top Introduction General Considerations Patient-Related Factors Factors Related to the... Templates for Planning of... Operative Approach Operative Plan Classification Systems Assessment of the Classification... Overview References

 

Chandler and Penenberg
In 1989, Chandler and Penenberg presented a new system for the classification of femoral bone loss in total hip arthroplasty as well as the results of treatment of forty-three hips in thirty-seven patients who were followed clinically for nineteen months⁸. This system for the classification of femoral bone loss includes six main categories, each of which may exist in isolation or in conjunction with another category. The six basic categories are calcar deficiency, trochanteric deficiency, cortical thinning, cortical perforation, femoral fracture, and circumferential deficiency (Table II). The classification system of Chandler and Penenberg was described with specific reference to treatment options involving use of allografts, which are not universally favored in all situations. Moreover, it does not quantify the described defects.

Trochanteric deficiency: A deficit of the greater trochanter is commonly associated with other femoral bone loss in patients who have a failed total hip arthroplasty. This situation may influence the operative approach.

Cortical thinning: Cortical thinning without actual loss of the cortex may be seen in association with failed total hip replacements.

Cortical perforation: Cortical perforation may be seen in isolation or in association with other lesions in hips that have a failed total hip replacement. These lesions may be caused by osteolysis or by penetration of a loose stem in varus alignment, or they may be iatrogenic injuries caused at the time of the revision operation either by inadvertent perforation or by intentional creation of a cortical window in order to facilitate cement extraction.

Fractures about or distal to the stem of a femoral component: Fracture at or distal to the stem of a femoral component may be seen either in the host femur or in a proximal femoral allograft used in a previous revision operation. Although the classification and management of periprosthetic fractures^12,37,70 is a separate issue outside the scope of this discussion, these fractures, when seen in conjunction with loose femoral components, may be considered as special types of bone loss encountered in revision arthroplasty.

Circumferential deficiency of the metaphysis and the proximal part of the diaphysis: With repeated revision total hip arthroplasties, bone deficiency may progress to such an extent that most of the proximal part of the femur becomes lost. In their classification system, Chandler and Penenberg distinguished between a severely involved femur, with only a thin cortical shell that is incapable of supporting a new prosthesis remaining, and a completely absent proximal part of the femur, such as that seen in the revision of a Girdlestone arthroplasty or after a custom proximal femoral replacement prosthesis has failed.

Endo-Klinik
In this classification system, bone loss associated with a failed cemented femoral component is divided into four grades¹⁶. This system is favored in European centers, particularly for describing series of hips treated with impaction allografting^14,25 (Table III). Although the system is useful for the understanding of failure of a stem inserted with cement, it is not easy to use when the radiographic signs are atypical and it has failed to gain widespread popularity.

Engh and Glassman
Engh and Glassman presented a simple system for the classification of femoral bone loss in total hip arthroplasty^18,19 (Table IV). With use of this system, Engh and Glassman were able to achieve optimum fixation of the femoral implant in 87 percent (ninety-two) of 106 hips that had moderate bone loss and in 71 percent (fifteen) of twenty-one hips that had severe bone loss.

A mild deficit refers to minimum bone loss that leaves the femoral neck and isthmus intact. The reconstruction in such instances is fairly simple, and the bone loss does not need to be addressed separately.

Moderate loss refers to damage of the femoral neck with the isthmus still intact. Such a degree of bone loss may be seen in association with failed cemented hip replacements that have moved into varus alignment, with destruction of the calcar and thinning of the bone of the proximal part of the femur, without perforation of the cortex and without loss of diaphyseal bone stock. This category accounts for the bulk of revision arthroplasties and precludes the use of a standard proximally coated implant inserted without cement. Although a standard-length prosthesis is adequate, it should, in the opinion of Engh and Glassman, be fully porous-coated to ensure adequate stability of the implant and diaphyseal fixation.

Severe bone loss refers to damage of the femoral neck and isthmus. An example of severe bone loss is loss of the calcar to or distal to the level of the lesser trochanter, with severe osteolysis of the femur extending well distal to the isthmus, in association with a failed long-stem cemented replacement. Stability of the implant can be achieved only with a long-stem prosthesis that extends into healthy bone more distally.

Paprosky et al.
Paprosky et al. described a new system for the classification of femoral bone loss in total hip arthroplasty, with particular reference to the ability of the femur to provide diaphyseal support for an extensively coated femoral component inserted without cement⁵⁵. This classification system describes three basic types of bone loss (Table V). It provides very useful guidance with regard to the type of prosthetic reconstruction that the bone can support, and it clearly defines the need for allograft support. However, the system is complex, it is difficult to apply to revisions of cemented implants, and it does not include deficits in the greater trochanter.

Type-2 hips are characterized by more extensive metaphyseal bone loss. The calcar is completely absent, and there is major loss of anteroposterior bone. However, the diaphysis remains intact and supportive. There are three subtypes in this category. In type 2A, the calcar is lost to the level of the lesser trochanter, but bone damage does not extend into the subtrochanteric region and the metaphysis is not as supportive as it is in type 1. In type 2B, there is loss of the lateral portion of the metaphysis. In type 2C, the most severe of these subtypes, there is loss or marked weakening of the medial subtrochanteric metaphyseal bone, but the diaphysis remains intact.

Type-3 lesions represent the most severe type of bone loss, and they are characterized by loss of both metaphyseal and diaphyseal bone stock. These lesions are subdivided in a manner similar to that used for type-2 lesions, but there is diaphyseal extension of the defects. The entire proximal part of the femur is deficient and needs to be bypassed or replaced for adequate fixation.

Mallory
As part of a comprehensive report on technical aspects of preparation of the proximal part of the femur in revision total hip arthroplasty without cement, Mallory classified femoral defects into three types on the basis of the bone loss in the cortex and the medullary contents of the proximal aspect of the femur⁴⁶ (Table VI). The classification system is useful in that it defines cortical and medullary bone loss, which clearly guides reconstruction, but it fails somewhat in that type IIIB, in particular, covers a range of trochanteric and diaphyseal bone loss for which there are a number of possible solutions.

In a type-II defect, the medullary contents are lost and the proximal part of the femur is a cortical shell with an intact cortical tube. This type of defect may be seen in revision arthroplasties in which cement has intruded well into the interstices of the cancellous bone of the proximal part of the femur or in the revision of hips with enough endosteal osteolysis to erode the proximal part of the femur without substantially disrupting the cortical shell. A long-stem prosthesis may be necessary in these hips.

In a type-III defect, both the medullary contents and the cortical tube are destroyed. This type is divided into three subtypes. In type IIIA, bone loss is proximal to the lesser trochanter. In type IIIB, it extends to a level between the lesser trochanter and the isthmus. In type IIIC, it is so severe that it includes most of the proximal part of the femur. Mallory suggested the use of fresh-frozen proximal femoral allografts for the treatment of type-IIIB and type-IIIC defects.

In the study of 160 hips by Mallory⁴⁶, 30 percent (forty-eight) of the defects were type I, 60 percent (ninety-six) were type II, and 10 percent (sixteen) were type III. All of the patients who had a type-I or type-II defect had a good or excellent result.

Gross et al.
In order to allow a better understanding of bone-grafting of the femur in revision total hip arthroplasty, Gross et al. proposed a simple system for the classification of femoral bone loss²⁸. Their classification system has two main categories: intraluminal loss and cortical loss (Table VII). The system is relatively straightforward and easy to remember and to apply, but combined cortical and medullary defects are not considered.

A femur with some loss of cortical bone is considered to have cortical bone loss. Cortical defects are divided into two subcategories: noncircumferential bone loss, for which only strut grafts are needed, and circumferential bone loss, for which a segmental graft is needed. Noncircumferential cortical bone loss does not include the entire circumference of the bone. The loss is full-thickness but incomplete. A circumferential cortical defect is full-thickness and complete. Circumferential cortical bone loss is further divided into two subtypes: calcar and proximal femoral. Calcar circumferential cortical bone loss is restricted to the region of the calcar and is less than three centimeters in length. In proximal femoral bone loss, the proximal part of the femur has more than three centimeters of circumferential bone loss and is unable to support a standard implant.

Johnston et al.
In recommending a uniform nomenclature for describing the results of total hip replacement, Johnston et al. suggested standardized terms for the radiographic evaluation of the femoral component³⁶. As part of an extensive reporting system, calcar resorption was described in terms of loss of height and thickness (in millimeters). Johnston et al. suggested that resorption of the shaft, loss of bone density, and endosteal cavitation should be recorded on the basis of the seven zones described by Gruen et al.²⁹ on the anteroposterior radiograph and an additional seven zones on the lateral radiograph. They suggested that the extent of endosteal cavitation be reported in terms of its length and width (in millimeters).

Gustilo and Pasternak
In this classification system, four categories are used to describe loss of femoral bone stock in revision arthroplasty³⁰. In their series, in which the bulk of revisions were performed for type-II and type-III bone loss, Gustilo and Pasternak demonstrated that the postoperative Harris hip scores were highest for the patients who had had type-I bone loss preoperatively and were lowest for those who had had type-IV.

Type I indicates minimum endosteal or inner cortical bone loss; type II, enlargement of the proximal part of the canal with cortical thinning of at least 50 percent and sometimes a defect of the lateral wall with an intact circumferential wall; type III, a defect of the posteromedial wall involving the lesser trochanter, indicating instability; and type IV, total circumferential bone loss in varying distances distal to the lesser trochanter.

American Academy of Orthopaedic Surgeons Committee on the Hip
In 1993, D'Antonio et al. described the system for the classification of femoral bone loss recommended by the American Academy of Orthopaedic Surgeons Committee on the Hip¹¹ (Table VIII). This system was developed with the aim of facilitating the preoperative planning and operative treatment of femoral bone loss in both primary and revision hip arthroplasty. The two basic categories of bone loss are segmental and cavitary. In addition, categories for femoral ectasia, malalignment, stenosis, and discontinuity were introduced in order to provide a comprehensive system for the classification of the full range of bone abnormalities found in hip arthroplasty.

Cavitary deficiencies: A cavitary defect is defined as an excavation of the cancellous or endosteal cortical bone, without violation of the outer shell of the femur (Figs. 1-A and 1-B). There are three subclasses in this category. In mild cases, the defect may involve loss of cancellous bone only. In more severe cases, the defect involves thinning of the cortex secondary to endosteal erosion, particularly when osteolysis is present. The third subclass, ectasia, refers to an enlarged medullary canal that is often associated with marked thinning of the cortex. Ectasia is commonly seen in association with a failed total hip replacement, inserted with or without cement, and marked osteolysis.

View larger version (93K): [in this window] [in a new window]   Fig. 1-A: Anteroposterior radiograph of the pelvis, showing a cortical cavitary defect of the right femur with grade-II and level-II bone loss according to the system of the American Academy of Orthopaedic Surgeons11. At the operation, the femoral cortex was found to be very thin but intact medially.

View larger version (82K): [in this window] [in a new window]   Fig. 1-B: Radiograph made after impaction allografting and protection of the femur with cerclage cables and a strut allograft medially.

View larger version (81K): [in this window] [in a new window]   Fig. 2-A: Anteroposterior radiograph of a right hip that had combined segmental and cavitary defects with level-I and level-II bone loss according to the system of the American Academy of Orthopaedic Surgeons11. There is an intercalary segmental defect distally on the posterolateral side, where the stem was found to have penetrated the cortex.

View larger version (81K): [in this window] [in a new window]   Figs. 2-B and 2-C: Radiographs made after insertion of a fully porous-coated prosthesis with cement, with good distal diaphyseal fixation and a calcar replacement proximally. A trochanteric slide was used to facilitate the exposure without additional damage to the femoral bone stock. The area of bone loss in the lateral part of the femur was protected with cerclage cables and a strut allograft.

View larger version (50K): [in this window] [in a new window]   Figs. 2-B and 2-C: Radiographs made after insertion of a fully porous-coated prosthesis with cement, with good distal diaphyseal fixation and a calcar replacement proximally. A trochanteric slide was used to facilitate the exposure without additional damage to the femoral bone stock. The area of bone loss in the lateral part of the femur was protected with cerclage cables and a strut allograft.

Femoral stenosis: This category refers to relative or absolute narrowing of the medullary canal of the femur. It may be seen at the site of a previous fracture of the femur, at the tip of a loose stem inserted without cement, or in dysplasia of the hip.

Femoral discontinuity: Femoral discontinuity refers to a fracture of the femur. Femoral discontinuity seen during primary hip replacement may have been the result of a nonunion of an old fracture. That seen during revision hip replacement may be an acute periprosthetic fracture or a nonunion of a periprosthetic fracture.

Level of bone loss: In addition to the quality of bone stock, the classification system of the American Academy of Orthopaedic Surgeons attempts to address the level of bone loss. For this purpose, the femur is divided into three levels. Level I is defined as bone proximal to the inferior portion of the lesser trochanter. Level II is the area between the inferior border of the lesser trochanter and ten centimeters distal to it, and level III is distal to level II.

System for grading of bone loss: In addition to describing the quality of bone and the location of bone loss, this classification system attempts to quantify the amount of remaining host bone. In grade I, there is minimum bone loss and host-prosthesis contact is maintained; no bone-grafting is needed. In grade II, there is some loss of host-prosthesis contact; however, the host bone is still able to support the prosthesis, and only morseled bone graft is needed. In grade III, there is such loss of host-prosthesis contact that a structural bone graft (such as a proximal femoral allograft) is needed for the reconstruction (Figs. 3-A, 3-B, 3-C and 3-D).

View larger version (49K): [in this window] [in a new window]   Fig. 3-A: Anteroposterior radiograph of a right hip, showing a combined defect with grade-III bone loss according to the system of the American Academy of Orthopaedic Surgeons11.

View larger version (64K): [in this window] [in a new window]   Fig. 3-B Lateral radiograph of the hip, showing a combined defect with grade-III bone loss according to the system of the American Academy of Orthopaedic Surgeons11.

View larger version (98K): [in this window] [in a new window]   Fig. 3-C Radiographs made after replacement of the proximal aspect of the femur with a segmental allograft. The implant was cemented into the allograft but not into the host bone distally. A step cut was made to improve the stability of the graft-host junction, which was reinforced further with cerclage wires, host bone medially, and a strut allograft laterally.

View larger version (60K): [in this window] [in a new window]   Fig. 3-D Radiographs made after replacement of the proximal aspect of the femur with a segmental allograft. The implant was cemented into the allograft but not into the host bone distally. A step cut was made to improve the stability of the graft-host junction, which was reinforced further with cerclage wires, host bone medially, and a strut allograft laterally.

	Assessment of the Classification Systems

Top Introduction General Considerations Patient-Related Factors Factors Related to the... Templates for Planning of... Operative Approach Operative Plan Classification Systems Assessment of the Classification... Overview References

 
We assessed the intraobserver and interobserver agreement for the systems developed for the classification of femoral bone loss by the American Academy of Orthopaedic Surgeons¹¹, Paprosky et al.⁵⁵, and Mallory⁴⁶. These three systems were chosen as they are the most commonly referenced systems for the classification of femoral bone loss. In our assessment, fifty radiographs of failed femoral components with associated bone loss were evaluated by three reconstructive orthopaedic surgeons (so-called experts) and three residents (so-called nonexperts)³⁸. Each observer also assessed the radiographs on two separate occasions at least two weeks apart. We used the unweighted kappa statistic to establish levels of agreement. The criteria of Landis and Koch were used in the interpretation of the results⁴¹. According to those criteria, a kappa value of as much as 0.20 signified slight agreement; 0.21 to 0.40, fair agreement; 0.41 to 0.60, moderate agreement; 0.61 to 0.80, substantial agreement; and more than 0.80, almost perfect agreement. For both the experts and the nonexperts, the intraobserver agreement for the three classification systems was only moderate (kappa range, 0.43 to 0.62) and the interobserver agreement for all three systems was only slight (kappa range, 0.12 to 0.29). It should be noted, however, that in clinical practice these classifications are often finalized on the basis of the intraoperative findings. Our results indicate that these classification systems, in isolation, do not provide reliable information for the preoperative assessment of loss of femoral bone stock. Furthermore, because of their limited reliability, these classification systems have limited value in the comparison of the results from different centers and in the comparison of the results of different operative interventions.

	Overview

Top Introduction General Considerations Patient-Related Factors Factors Related to the... Templates for Planning of... Operative Approach Operative Plan Classification Systems Assessment of the Classification... Overview References

 
A single comprehensive classification system that can adequately describe all types of bone loss associated with hip arthroplasty should become a standard for reporting purposes. There is a need for a critical appraisal of the classification systems currently in use and, through a consensus, for development of a system that will permit comparison between the reported results of different techniques. Although no one classification system is ideal, the one proposed by the American Academy of Orthopaedic Surgeons Committee on the Hip is the most comprehensive and the most consistently used. It addresses not only revision total hip arthroplasty but also primary hip replacement. It also addresses other conditions related to problems with the bone stock, such as those resulting from a previous hip arthrodesis on the acetabular side and femoral stenosis and malalignment on the femoral side. The only drawback to this classification system is its complexity; however, the problem of acetabular and femoral bone loss is of sufficient complexity and variety that a simple classification system, although ideal, cannot be comprehensive.

Regardless of the absence of a common language and a comprehensive classification system that is applicable to all types of reconstructions, it is clear that femoral bone loss is a problem that will continue to challenge orthopaedic surgeons. It is only by careful and methodical analysis of patients who have femoral bone loss and by meticulous attention being paid to detail in preoperative evaluation and investigation, operative planning, and the recording of outcomes that we will be able to improve our treatment of this difficult problem.

NOTE: The fellowship training of one of the authors (F. S. H.) was supported, in part, by the John Charnley and British Orthopaedic Association/Wishbone Trusts and by the Norman Capener Travelling Fellowship.

	Footnotes

 
*Printed with permission of the American Academy of Orthopaedic Surgeons. This article will appear in Instructional Course Lectures, Volume 49, American Academy of Orthopaedic Surgeons, Rosemont, Illinois, March 2000.

No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article. No funds were received in support of this study.

Department of Orthopaedics, Laurel Pavilion, Vancouver General Hospital, 910 West Tenth Avenue, Third Floor, Vancouver, British Columbia V5Z 4E3, Canada. E-mail address for Dr. Masri: masri@unixg.ubc.ca.

	References

Top Introduction General Considerations Patient-Related Factors Factors Related to the... Templates for Planning of... Operative Approach Operative Plan Classification Systems Assessment of the Classification... Overview References

 

1. Abraham, W. D., and Dimon, J. H., III: Leg length discrepancy in total hip arthroplasty. Orthop. Clin. North America, 23: 201-209, 1992.[Medline]
2. al-Salman, M.; Taylor, D. C.; Beauchamp, C. P.; and Duncan, C. P.: Prevention of vascular injuries in revision total hip replacement. Canadian J. Surg., 35: 261-264, 1992.[Medline]
3. Amstutz, H. C., and Sakai, D. N.: Total joint replacement for ankylosed hips. Indications, technique, and preliminary results. J. Bone and Joint Surg., 57-A: 619-625, July 1975.[Abstract/Free Full Text]
4. Ballinger, P. W.: Merrill's Atlas of Radiographic Positions and Radiologic Procedures. Ed. 6. St. Louis, C. V. Mosby, 1986.
5. Bargar, W. L.: Shape the implant to the patient. A rationale for the use of custom-fit cementless total hip implants. Clin. Orthop., 249: 73-78, 1989.
6. Bethea, J. S., III; DeAndrade, J. R.; Fleming, L. L.; Lindenbaum, S. D.; and Welch, R. B.: Proximal femoral fractures following total hip arthroplasty. Clin. Orthop., 170: 95-106, 1982.
7. Carter, L. W.; Stovall, D. O.; and Young, T. R.: Determination of accuracy of preoperative templating of noncemented femoral prostheses. J. Arthroplasty, 10: 507-513, 1995.[Medline]
8. Chandler, H. P., and Penenberg, B. L.: Bone Stock Deficiency in Total Hip Replacement: Classification and Management. Thorofare, New Jersey, Slack, 1989.
9. Charnley, J., and Feagin, J. A.: Low-friction arthroplasty in congenital subluxation of the hip. Clin. Orthop., 91: 98-113, 1973.
10. Christensen, C. M.; Seger, B. M.; and Schultz, R. B.: Management of intraoperative femur fractures associated with revision hip arthroplasty. Clin. Orthop., 248: 177-180, 1989.
11. D'Antonio, J.; McCarthy, J. C.; Bargar, W. L.; Borden, L. S.; Cappelo, W. N.; Collis, D. K.; Steinberg, M. E.; and Wedge, J. H.: Classification of femoral abnormalities in total hip arthroplasty. Clin. Orthop., 296: 133-139, 1993.
12. Duncan, C. P., and Masri, B. A.: Fractures of the femur after hip replacement. In Instructional Course Lectures, American Academy of Orthopaedic Surgeons. Vol. 44, pp. 293-304. Rosemont, Illinois, American Academy of Orthopaedic Surgeons, 1995.
13. Egan, K. J., and Di Cesare, P. E.: Intraoperative complications of revision hip arthroplasty using a fully porous-coated straight cobalt-chrome femoral stem. J. Arthroplasty, 10 (Supplement): 45-S51, 1995.
14. Elting, J. J.; Zicat, B. A.; Mikhail, W. E. M.; Hubbell, J. C.; and House, B. S.: Impaction grafting: preliminary report of a new method for exchange femoral arthroplasty. Orthopedics, 18: 107-112, 1995.
15. Emerson, R. H., Jr.; Malinin, T. I.; Cuellar, A. D.; Head, W. C.; and Peters, P. C.: Cortical strut allografts in the reconstruction of the femur in revision total hip arthroplasty. A basic science and clinical study. Clin. Orthop., 285: 35-44, 1992.
16. Engelbrecht, E., and Heinert, K.: Klassification und Behandlungsrichtlinien von Kflochensubstanzverlusten bei Revisions operationen am Huftgelenk-mittelfristige Ergebnisse. Primare und Revisionsalloarthroplastik Hrsg-Endo-Klinik, Hamburg, pp. 189-201. Berlin, Springer, 1987.
17. Engh, C. A.; Glassman, A. H.; Griffin, W. L.; and Mayer, J. G.: Results of cementless revision for failed cemented total hip arthroplasty. Clin. Orthop., 235: 91-110, 1988.
18. Engh, C. A., and Glassman, A. H.: Cementless revision of failed total hip replacement. Orthop. Rev., 19 (Supplement): 23-28, 1990.
19. Engh, C. A., and Glassman, A. H.: Cementless revision of failed total hip replacement: an update. In Instructional Course Lectures, American Academy of Orthopaedic Surgeons. Vol. 40, pp. 189-197. Park Ridge, Illinois, American Academy of Orthopaedic Surgeons, 1991.
20. Engh, C. A.; Engh, C. A., Jr.; Cadambi, A.; Lauro, G.; and Piston, R. W.: Cementless revision of failed total hip arthroplasty. Tech. Orthop., 7: 9-26, 1993.
21. Fehrman, D. A.; McBeath, A. A.; DeSmet, A. A.; and Tuite, M. J.: Imaging barium-free bone cement. Am. J. Orthop., 25: 172-174, 1996.[Medline]
22. Fitzgerald, R. H., Jr.; Brindley, G. W.; and Kavanagh, B. F.: The uncemented total hip arthroplasty. Intraoperative femoral fractures. Clin. Orthop., 235: 61-66, 1988.
23. Fredin, H.: Late fracture of the femur following perforation during total hip arthroplasty. A report of two cases. Acta Orthop. Scandinavica, 59: 331-332, 1988.[Medline]
24. Garbuz, D. S.; Masri, B. A.; and Duncan, C. P.: Periprosthetic fractures of the femur: principles of prevention and management. In Instructional Course Lectures, American Academy of Orthopaedic Surgeons. Vol. 47, pp. 237-242. Rosemont, Illinois, American Academy of Orthopaedic Surgeons, 1998.
25. Gie, G. A.; Linder, L.; Ling, R. S. M.; Simon, J.-P.; Slooff, T. J. J. H.; and Timperley, A. J.: Impacted cancellous allografts and cement for revision total hip arthroplasty. J. Bone and Joint Surg., 75-B(1): 14-21, 1993.
26. Glassman, A. H., and Engh, C. A.: The removal of porous-coated femoral hip stems. Clin. Orthop., 285: 164-180, 1992.
27. Gross, A. E.: Revision arthroplasty of the hip using allograft bone. In Allografts in Orthopaedic Practice, pp. 147-173. Edited by A. A. Czitrom and A. E. Gross. Baltimore, Williams and Wilkins, 1992.
28. Gross, A. E.; Allan, D. G.; Lavoie, G. J.; and Oakeshott, R. D.: Revision arthroplasty of the proximal femur using allograft bone. Orthop. Clin. North America, 24: 705-715, 1993.[Medline]
29. Gruen, T. A.; McNeice, G. M.; and Amstutz, H. G.: "Modes of failure" of cemented stem-type femoral components. A radiographic analysis of loosening. Clin. Orthop., 141: 17-27, 1979.
30. Gustilo, R. B., and Pasternak, H. S.: Revision total hip arthroplasty with titanium ingrowth prosthesis and bone grafting for failed cemented femoral component loosening. Clin. Orthop., 235: 111-119, 1988.
31. Harris, W. H., and Barrack, R. L.: Developments in diagnosis of the painful total hip replacement. Orthop. Rev., 22: 439-447, 1993.[Medline]
32. Harris, W. H., and Barrack, R. L.: Contemporary algorithms for evaluation of the painful total hip replacement. Orthop. Rev., 22: 531-539, 1993.[Medline]
33. Hartofilakidis, G.; Stamos, K.; and Karachalios, T.: Treatment of high dislocation of the hip in adults with total hip arthroplasty. Operative technique and long-term clinical results. J. Bone and Joint Surg., 80-A: 510-517, April 1998.[Abstract/Free Full Text]
34. Herzwurm, P. J.; Walsh, J.; Pettine, K. A.; and Ebert, F. R.: Prophylactic cerclage: a method of preventing femur fracture in uncemented total hip arthroplasty. Orthopedics, 15: 143-146, 1992.[Medline]
35. Incavo, S. J.; DiFazio, F.; Wilder, D.; Howe, J. G.; and Pope, M.: Longitudinal crack propagation in bone around femoral prosthesis. Clin. Orthop., 272: 175-180, 1991.
36. Johnston, R. C.; Fitzgerald, R. H., Jr.; Harris, W. H.; Poss, R.; Müller, M. E.; and Sledge, C. B.: Clinical and radiographic evaluation of total hip replacement. A standard system of terminology for reporting results. J. Bone and Joint Surg., 72-A: 161-168, Feb. 1990.[Free Full Text]
37. Kelley, S. S.: Periprosthetic femoral fractures. J. Am. Acad. Orthop. Surgeons, 2: 164-172, 1994.[Abstract]
38. Kerry, R. M.; Masri, B. A.; Garbuz, D. S.; and Duncan, C. P.: The reliability of femoral bone loss classifications. Read at the Combined Meeting of the British and Irish Orthopaedic Associations, Dublin, Oct. 5-6, 1998.
39. Kerry, R. M.; Masri, B. A.; Garbuz, D. S.; and Duncan, C. P.: The vascularised scaphoid window for access to the femoral canal in revision total hip arthroplasty. Unpublished data.
40. Kilgus, D. J.; Amstutz, H. C.; Wolgin, M. A.; and Dorey, F. J.: Joint replacement for ankylosed hips. J. Bone and Joint Surg., 72-A: 45-54, Jan. 1990.[Abstract/Free Full Text]
41. Landis, J. R., and Koch, G. G.: The measurement of observer agreement for categorical data. Biometrics, 33: 159-174, 1977.[Medline]
42. Larson, J. E.; Chao, E. Y. S.; and Fitzgerald, R. H.: Bypassing femoral cortical defects with cemented intramedullary stems. J. Orthop. Res., 9: 414-421, 1991.[Medline]
43. Lewallen, D. G.: Neurovascular injury associated with hip arthroplasty. J. Bone and Joint Surg., 79-A: 1870-1880, Dec. 1997.[Free Full Text]
44. Lonner, J. H.; Desai, P.; Dicesare, P. E.; Steiner, G.; and Zuckerman, J. D.: The reliability of analysis of intraoperative frozen sections for identifying active infection during revision hip or knee arthroplasty. J. Bone and Joint Surg., 78-A: 1553-1558, Oct. 1996.[Abstract/Free Full Text]
45. McElfresh, E. C., and Coventry, M. B.: Femoral and pelvic fractures after total hip arthroplasty. J. Bone and Joint Surg., 56-A: 483-492, April 1974.[Abstract/Free Full Text]
46. Mallory, T. H.: Preparation of the proximal femur in cementless total hip revision. Clin. Orthop., 235: 47-60, 1988.
47. Mallory, T. H.; Kraus, T. J.; and Vaughn, B. K.: Intraoperative femoral fractures associated with cementless total hip arthroplasty. Orthopedics, 12: 23l-239, 1989.
48. Masri, B. A., and Duncan, C. P.: Classification of bone loss in total hip arthroplasty. In Instructional Course Lectures, American Academy of Orthopaedic Surgeons. Vol. 45, pp. 199-208. Rosemont, Illinois, American Academy of Orthopaedic Surgeons, 1996.
49. Masri, B. A.; Masterson, E. L.; and Duncan, C. P.: The classification and radiographic evaluation of bone loss in revision hip arthroplasty. Orthop. Clin. North America, 29: 219-227, 1998.[Medline]
50. Masri, B. A.; Campbell, D. G.; Garbuz, D. S.; and Duncan, C. P.: Seven specialized exposures for revision hip and knee replacement. Orthop. Clin. North America, 29: 229-240, 1998.[Medline]
51. Matos, M. H.; Amstutz, H. C.; and Machleder, H. I.: Ischemia of the lower extremity after total hip arthroplasty. Report of four cases. J. Bone and Joint Surg., 61-A: 24-27, Jan. 1979.[Abstract/Free Full Text]
52. Missakian, M. L., and Rand, J. A.: Fractures of the femoral shaft adjacent to long stem femoral components of total hip arthroplasty: report of seven cases. Orthopedics, 16: 149-152, 1993.[Medline]
53. Morrey, B. F.: Instability after total hip arthroplasty. Orthop. Clin. North America, 23: 237-248, 1992.[Medline]
54. Pak, J. H.; Paprosky, W. G.; Jablonsky, W. S.; and Lawrence, J. M.: Femoral strut allografts in cementless revision total hip arthroplasty. Clin. Orthop., 295: 172-178, 1993.
55. Paprosky, W. G.; Lawrence, J.; and Cameron, H.: Femoral defect classification: clinical application. Orthop. Rev., 19 (Supplement 9): 9-15, 1990.
56. Pazzaglia, U., and Byers, P. D.: Fractured femoral shaft through an osteolytic lesion resulting from the reaction to a prosthesis. A case report. J. Bone and Joint Surg., 66-B(3): 337-339, 1984.
57. Pellicci, P. M.; Inglis, A. E.; and Salvati. E. A.: Perforation of the femoral shaft during total hip replacement. Report of twelve cases. J. Bone and Joint Surg., 62-A: 234-240, March 1980.[Abstract/Free Full Text]
58. Reikeras, O.; Bjerkreim, I.; and Gundersson, R.: Total hip arthroplasty for arthrodesed hips. 5- to 13-year results. J. Arthroplasty, 10: 529-531, 1995.[Medline]
59. Reuben, J. D.; Chang, C.-H.; Akin, J. E.; and Lionberger, D. R.: A knowledge-based computer-aided design and manufacturing system for total hip replacement. Clin. Orthop., 285: 48-56, 1992.
60. Schmalzried, T. P.; Amstutz, H. C.; and Dorey, F. J.: Nerve palsy associated with total hip replacement. Risk factors and prognosis. J. Bone and Joint Surg., 73-A: 1074-1080, Aug. 1991.[Abstract/Free Full Text]
61. Schwartz, J. T., Jr.; Mayer, J. G.; and Engh, C. A.: Femoral fracture during non-cemented total hip arthroplasty. J. Bone and Joint Surg., 71-A: 1135-1142, Sept. 1989.[Abstract/Free Full Text]
62. Scott, R. D.; Turner, R. H.; Leitzes, S. M.; and Aufranc, O. E.: Femoral fractures in conjunction with total hip replacement. J. Bone and Joint Surg., 57-A: 494-501, June 1975.[Abstract/Free Full Text]
63. Spangehl, M. J.; Younger, A. S. E.; Masri, B. A.; and Duncan, C. P.: Diagnosis of infection following total hip arthroplasty. In Instructional Course Lectures, American Academy of Orthopaedic Surgeons. Vol. 47, pp. 285-295. Rosemont, Illinois, American Academy of Orthopaedic Surgeons, 1998.
64. Stuchin, S. A.: Femoral shaft fracture in porous and press-fit total hip arthroplasty. Orthop. Rev., 19: 153-159, 1990.[Medline]
65. Sydney, S. V., and Mallory, T. H.: Controlled perforation. A safe method of cement removal from the femoral canal. Clin. Orthop., 253: 168-172, 1990.
66. Symeonides, P. P.; Pournaras, J.; Petsatodes, G.; Christoforides, J.; Hatzokos, I.; and Pantazis, E.: Total hip arthroplasty in neglected congenital dislocation of the hip. Clin. Orthop., 341: 55-61, 1997.
67. Talab, Y. A.; States, J. D.; and Evarts, C. McC.: Femoral shaft perforation. A complication of total hip reconstruction. Clin. Orthop., 141: 158-165, 1979.
68. Woolson, S. T.: Leg length equalization during total hip replacement. Orthopedics, 13: 17-21, 1990.[Medline]
69. Xenakis, T. A.; Gelalis, I. D.; Koukoubis, T. D.; Soucacos, P. N.; Vartziotis, K.; Kontoyiannis, D.; and Tatsis, C.: Neglected congenital dislocation of the hip. Role of computed tomography and computer-aided design for total hip arthroplasty. J. Arthroplasty, 1: 893-898, 1996.
70. Younger, A. S. E.; Dunwoody, I.; and Duncan, C. P.: Periprosthetic hip and knee fractures: the scope of the problem. In Instructional Course Lectures, American Academy of Orthopaedic Surgeons. Vol. 47, pp. 251-256. Rosemont, Illinois, American Academy of Orthopaedic Surgeons, 1998.
71. Younger, T. I.; Bradford, M. S.; Magnus, R. E.; and Paprosky, W. G.: Extended proximal femoral osteotomy. A new technique for femoral revision arthroplasty. J. Arthroplasty, 10: 329-338, 1995.[Medline]

CiteULike

Connotea

Del.icio.us

Facebook

Technorati

Twitter

This article has been cited by other articles:

				D. S. Garbuz, B. A. Masri, J. Esdaile, and C. P. Duncan Classification Systems in Orthopaedics J. Am. Acad. Ortho. Surg., July 1, 2002; 10(4): 290 - 297. [Abstract] [Full Text] [PDF]

This Article Extract Full Text (PDF) Free Letters to the Editor: Submit a response Alert me when this article is cited Alert me when Letters to the Editor are posted Alert me if a correction is posted Services E-mail this article to a friend Similar articles in this journal Alert me to new issues of the journal Add to My File Cabinet Download to citation manager Rights and Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by HADDAD, F. S. Articles by DUNCAN, C. P. Search for Related Content PubMed Articles by HADDAD, F. S. Articles by DUNCAN, C. P. Social Bookmarking                   What's this?

Stanford University Libraries' HighWire Press (TM) assists in the publication of JBJS Online.
Copyright © 1999 by The Journal of Bone and Joint Surgery, Inc. Online ISSN: 1535-1386.
The Journal of Bone and Joint Surgery®, JBJS®, JB&JS®, and eJBJS® are registered in the U.S. Patent and Trademark Office.