This Article Extract Full Text (PDF) Free CME: Take the activities for this article: Adult Hip Reconstruction Test 27: Winter 2008 (publication date February 15... CME 4: October, November, December 2007 (publication date January 4, 2008; ... [FREE Spanish Translation] Letters to the Editor: Submit a response Letters to the Editor: View responses 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 Similar articles in PubMed 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 Google Scholar Google Scholar Articles by Maheshwari, A. V. Articles by Dorr, L. D. Search for Related Content PubMed PubMed Citation Articles by Maheshwari, A. V. Articles by Dorr, L. D. Related Collections Current Concepts Review Adult Hip Social Bookmarking                   What's this?

Impingement of the Native Hip Joint

¹ Aditya V. Maheshwari, MD Aamer Malik, MD Lawrence D. Dorr, MD The Arthritis Institute, 501 East Hardy Street, Suite 300, Inglewood, CA 90301. E-mail address for L.D. Dorr: Patriciajpaul{at}yahoo.com

Investigation performed at The Arthritis Institute, Inglewood, California

Disclosure: In support of their research for or preparation of this work, one or more of the authors received, in any one year, outside funding or grants in excess of $10,000 from Zimmer. In addition, one or more of the authors or a member of his or her immediate family received, in any one year, payments or other benefits in excess of $10,000 or a commitment or agreement to provide such benefits from a commercial entity (OrthoSoft). No commercial entity paid or directed, or agreed to pay or direct, any benefits to any research fund, foundation, division, center, clinical practice, or other charitable or nonprofit organization with which the authors, or a member of their immediate families, are affiliated or associated.

	Introduction

Top Introduction Origin of Impingement Biomechanics of Impingement Clinical Features of... Imaging Studies Treatment Options References

 
Impingement at the hip is a common cause of osteoarthritis.

Impingement is mostly due to morphologic changes as a consequence of in utero malformation or childhood hip disease such as Legg-Calvé-Perthes disease or slipped capital femoral epiphysis.

On the basis of patterns and stages of labral and chondral injuries, impingement has been classified as cam type, pincer type, or mixed cam-pincer type.

The diagnosis is based on the medical history and the findings on physical examination and imaging studies.

Hip impingement is a mechanical problem, and nonoperative treatment will not correct the pathomechanics. Surgical correction should be considered prior to the onset of arthritis and must be designed to protect the vascularity of the femoral head.

Impingement of the hip joint has been a hidden disease until the current decade. Femoroacetabular impingement was identified as a dynamic cause of osteoarthritis by Ganz et al.^1-22, although Murray²³ and Stulberg et al.²⁴ had identified the so-called tilt deformity and pistol-grip deformity, respectively, as probable causes.

Impingement within the hip joint is an abutment conflict between the bone of the femur and that of the pelvis. Impingement in young patients is a mechanical problem caused by biological structural patterns or by overuse, particularly in athletes or in very flexible hips. Leunig et al.¹⁴ observed evidence of impingement with aging in the acetabula of patients (sixty-nine to ninety-seven years of age) with a femoral neck fracture and not uncommonly in cadavers of donors who were sixty to ninety years old at the time of death.

	Origin of Impingement

Top Introduction Origin of Impingement Biomechanics of Impingement Clinical Features of... Imaging Studies Treatment Options References

 
The cause of impingement in the osseous hip can be developmental, as a result of childhood conditions such as Legg-Calvé-Perthes disease and slipped capital femoral epiphysis; it may also result from posttraumatic or post-osteotomy morphologic changes in inclination and anteversion angles^{1-3,7,10,14,18-21}. Extra-articular impingement of the intertrochanteric bone of a deformed proximal part of the femur can occur, but that is not the focus of this review. Instead, we will focus on the skeletal changes that have their destiny determined by the perinatal formative months. Impingement caused by structural deformities (morphologic dysplasia) may still be the single most common cause of osteoarthritis^25,26. Because osteoarthritis is familial and culturally selective, these deformities can be assumed to be genetic in origin.

Rotation of the hips occurs in the first two years of life with increasing anteversion, particularly after children begin standing, and then it gradually decreases to the values found in adults^27-29. Watanabe²⁹ examined 144 stillborn fetuses and embryos, after twenty to twenty-four weeks of gestation or more, and found femoral rotation ranging from 10° of retroversion to 35° of anteversion. External rotation was more common in males, and internal rotation was more common in females. Pitkow²⁷ observed that, of 500 children with gait deformities, forty-five (9%) had an external rotation contracture presumed to be caused by an intrauterine position of flexion and external rotation of the hips. A persistent external rotation posture most likely led to the development of retroversion of the acetabulum²⁷. Pitkow observed that about 5% of the children had a persistent external rotation contracture of the limb, a finding that correlates with the observation by Giori and Trousdale³⁰ that 5% of the general adult population (five of ninety-nine people) have radiographic evidence of acetabular retroversion. Measurement of the McKibbin instability index^28,31 in the hips of children confirms the variability of hip rotation. McKibbin³¹ observed that the combined anteversion of the acetabulum and femur in newborns ranged from <20° to >40°. Combined anteversion of 30° to 40° is considered normal in adults, and Tönnis and Heinecke²⁸ observed that 181 (62%) of 290 hips had <30° of combined anteversion and 110 (38%) had <20°.

The prevalence of acetabular retroversion causing impingement in patients with osteoarthritis is high^30,32. Retroversion of the acetabulum alone is termed pincer impingement because of overcoverage of the femoral head by the prominent anterior aspect of the acetabular rim. The amount of retroversion of the acetabulum measured in four different radiographic studies ranged from 5% to 20%^30,32-34. We found that, of 178 arthritic hips undergoing total hip replacement with use of computer navigation, eighty-nine (50%) showed acetabular anteversion of <10°, a rate that is more than twice that measured on radiographs (unpublished data). The difference in the rates may be due to the fact that we focused on arthritic hips and were measuring the structure of the acetabulum, or the fact that we adjusted for the tilt of the pelvis, which cannot easily be done with standard radiographs.

An abnormal femoral head-neck ratio (offset) is the most common impingement deformity. Stulberg et al.²⁴ termed this a pistol-grip deformity. It causes cam impingement of the femoral neck against the anterior aspect of the acetabular rim during flexion, adduction, and internal rotation. Stulberg et al. observed this deformity in thirty (40%) of seventy-five hips with osteoarthritis (66% of the hips in males and 10% of those in females). Retroversion of the femur can occur without an obvious pistol-grip deformity. Some retroversion of the acetabulum combined with some retroversion of the femur can result in a McKibbin index of <20°, which is considered to be severe retroversion²⁸. With use of computer navigation, we observed that 102 (57%) of 178 hips had combined anteversion of <20° (unpublished data). Again, this percentage may be high because we performed the measurements only in arthritic hips.

	Biomechanics of Impingement

Top Introduction Origin of Impingement Biomechanics of Impingement Clinical Features of... Imaging Studies Treatment Options References

 
On the basis of the pattern and stages of chondral and labral injuries, two distinct types of femoroacetabular impingement have been identified (Fig. 1)⁷. The first type, cam impingement, is more common in young athletic men. It is caused by the jamming of an abnormal femoral head, or head-neck junction (resulting in a reduced head-neck ratio or offset), against the acetabulum, especially with flexion and internal rotation. The prevalence of cam impingement in men is consistent with the finding of external rotation deformities being more common in male children²⁹.

Fig. 1: Biomechanics of hip impingement as seen on an axial view of the hip joint. The reduced clearance leads to repetitive abutment between the femur and the acetabular rim. A: A normal hip. B: Reduced femoral head-neck offset (cam-type impingement). C: Excessive overcoverage of the femoral head (pincer-type impingement). D: Combination of cam and pincer types of impingement. (Reproduced, with modification, from: Lavigne M, Parvizi J, Beck M, Siebenrock KA, Ganz R, Leunig M. Anterior femoroacetabular impingement: part I. Techniques of joint preserving surgery. Clin Orthop Relat Res. 2004;418:62. Reprinted with permission and copyright © of Lippincott Williams and Wilkins.)

The second type, pincer impingement, is most common in middle-aged athletic women. It is the result of linear contact between a prominent anterior aspect of the acetabular rim and the femoral head or femoral head-neck junction such as occurs with coxa profunda, acetabular protrusion, or retroversion of the acetabulum⁷. The femoral head may have normal morphologic features or may have an indentation caused by the abutment against the prominent anterior aspect of the acetabular rim. The repeated microtrauma may result in an ossified labrum, which compounds the impingement.

Cam and pincer impingement rarely occur in isolation, and the combination has been termed mixed cam-pincer impingement¹. With this disorder, an abnormal femoral head or head-neck junction articulates with an abnormal acetabulum. In one epidemiological study of 149 hips with impingement, twenty-six (17.4%) had isolated cam impingement, sixteen (10.7%) had isolated pincer impingement, and 107 (71.8%) had combined cam-pincer impingement¹.

In the cam type of impingement, the resulting shear forces produce an outside-in abrasion of the acetabular cartilage and/or its avulsion from the labrum and the subchondral bone in the anterosuperior rim area⁷. Chondral avulsion in turn can lead to a tear or detachment of the initially uninvolved labrum. In contrast, the first structure to fail when there is pincer-type impingement is the acetabular labrum. The continued impact of the abutment results in the degeneration of the labrum with intrasubstance ganglion formation, or ossification that deepens the socket and increases anterior impingement. The persistent abutment, which often is anterior, with chronic leverage of the head in the acetabulum can result in injury to the cartilage directly opposite—i.e., in the posteroinferior aspect of the acetabulum (termed the contre-coup region)⁷. Chondral lesions in hips with pincer impingement often are limited to a small area of the rim and usually include only a narrow strip of acetabular cartilage and therefore are more benign. This is in contrast to what occurs with cam impingement, which can cause deep chondral lesions and/or extensive labral tears^7,11. Arthritis develops when damage at the labral-cartilage junction extends to the articular cartilage and subchondral bone. This damage extends by shearing of the adjacent articular cartilage from the underlying subchondral bone^18,35. In the aberrant, nonspherical area of the femoral head in young patients with femoroacetabular impingement, the hyaline cartilage showed clear degeneration similar to that in hips affected by osteoarthritis²². Wagner et al.²² described damage to the acetabular cartilage as a result of impingement in young patients, and Leunig et al.¹⁴ observed damage to the acetabular cartilage and labrum resulting from impingement in elderly patients without arthritis.

	Clinical Features of Femoroacetabular Impingement

Top Introduction Origin of Impingement Biomechanics of Impingement Clinical Features of... Imaging Studies Treatment Options References

 
History
A young or middle-aged patient who, at the time of presentation, describes the gradual onset of unilateral hip pain that is predominantly in the groin must be considered to have femoroacetabular impingement^7,36. Occasionally, the pain is bilateral³⁵. If the patient presents with knee pain, it is critical that the surgeon think about the hip as the possible cause. The patient may report mechanical symptoms (locking, catching, and giving-way) indicative of a labral tear or a delamination injury of the articular cartilage³⁵. The pain is often intermittent and exacerbated by an excessive demand on hip flexion, such as occurs with athletic activities and in very flexible hips. Patients with impingement can have pain with these activities and even while sitting with the hip extremely flexed. In a recent study by Burnett et al.³⁷, sixty (91%) of sixty-six patients had activity-related pain and forty-seven (71%) had night pain. Thus, a diagnosis of impingement must be considered when a patient presents with this history. Jäger et al.³⁸ reported a mean delay of 5.4 years between the onset of symptoms and the diagnosis, and Burnett et al.³⁷ reported a mean delay of twenty-one months, with an average of 3.3 previous doctor visits. Patients have even had laparoscopy, spine surgery, or an inguinal hernia repair as the result of a missed diagnosis caused by confusing symptoms⁷.

Physical Examination
Burnett et al.³⁷ found that twenty-six (39%) of sixty-six patients with femoroacetabular impingement had a limp, twenty-five (38%) had a positive Trendelenburg sign, and sixty-three (95%) had a positive impingement sign. The most important physical finding is the result of the impingement test, which reveals limitation of internal rotation and adduction in flexion out of proportion with limitations of other motions⁷. Osteoarthritis is more likely to produce globally restricted motion. With the patient supine, the hip is internally rotated as it is passively flexed to approximately 90° and adducted. Flexion and adduction cause abutment of the femoral neck on the acetabular rim. Further passive internal rotation induces shear forces at the labrum and can create a sharp pain when there is a labral and/or a chondral lesion. The pelvis must be stabilized so that the end point of hip flexion can be clearly determined.

View larger version (23K): [in this window] [in a new window]   Fig. 2-A Line drawing representing an anteroposterior radiograph showing the pistol-grip deformity (arrow).

	Imaging Studies

Top Introduction Origin of Impingement Biomechanics of Impingement Clinical Features of... Imaging Studies Treatment Options References

 
Plain radiographs are the most important imaging studies for the diagnosis of impingement. The recommended radiographs are an anteroposterior view of the pelvis and a cross-table lateral view of the hip in 15° of internal rotation¹⁷. Tilting of the pelvis on the anteroposterior view may obscure overcoverage or undercoverage of the femoral head as well as affect the measurement of acetabular anteversion. An optimal anteroposterior pelvic radiograph is one on which the coccyx points toward the symphysis pubis with a distance of no more than 2 cm between them and with symmetrical teardrops, obturator foramina, and iliac wings (Figs. 2-A, 2-B, and 2-C)^7,20. Siebenrock et al.²⁰ suggested that the optimal distance between the symphysis pubis and the middle of the sacrococcygeal joint is 25 to 40 mm in females and 40 to 55 mm in males. A reconstructed computed tomography scan to correct for tilt can be used in place of a tilted anteroposterior pelvic radiograph^13,28,39.

View larger version (191K): [in this window] [in a new window]   Fig. 2-B and Fig. 2-C Fig. 2-B Anteroposterior pelvic radiograph showing reduced offset at the head-neck junction (the pistol-grip deformity) of both hips, with end-stage osteoarthritis in the left hip. Fig. 2-C Lateral radiograph of the left hip, showing the sagittal appearance of the pistol-grip deformity.

The morphologic features on the radiograph that favor a diagnosis of anterior impingement are a congruent but nonspherical femoral head, a short femoral neck, and/or a small head-to-neck ratio with a reduced head-neck offset. The most prevalent finding on the anteroposterior radiograph is a flattened head-neck junction or a pistol-grip deformity²⁴ (Fig. 2-B). A pistol-grip deformity is characterized by flattening of the usually concave surface of the femoral head, a bump on the anterolateral surface of the femoral neck, a so-called medial hook at the medial head-neck junction, and failure of the femoral head to be centered over the femoral neck^4,24,26,40. With milder forms of anterior impingement, the findings may be seen on only lateral radiographs, which show displacement of the head over the neck and the medial hook^4,24,26,40. Specific acetabular changes include an os acetabuli or ossification of the acetabular rim.

Pincer impingement is commonly associated with acetabular protrusion, coxa profunda, or a retroverted acetabulum¹. An additional observation on plain radiographs may be juxta-articular fibrocystic changes (herniation pits) at the anterosuperior aspect of the femoral neck^13,35,41. Fluoroscopy of the hip can be used in equivocal cases to observe whether impingement occurs with dynamic motion of the hip³⁶.

Radiographic Measurements
A distance between the anterior and posterior margins of the acetabulum of either greater or less than the normal distance of 1.5 cm can define the presence of abnormal version²⁸. Acetabular retroversion is also indicated by the crossover and posterior wall signs^{18,20,21,28,34} (Figs. 3-A, 3-B, and 3-C). The head-neck off-set can be measured quantitatively on a cross-table radiograph by drawing a line bisecting the longitudinal axis of the femoral neck (which may not pass through the center of the head), a parallel line tangential to the anterior aspect of the femoral neck, and a third line parallel to the others and tangential to the anterior aspect of the femoral head⁴. The perpendicular distance between the lines tangential to the neck and the anterior aspect of the head is defined as the head-neck offset, with normal being an absolute value of 9 mm or a ratio of the head diameter of 0.17^4,36,42.

View larger version (24K): [in this window] [in a new window]   Fig. 3-A Line drawing representing an anteroposterior radiograph demonstrating the appearance of a retroverted acetabulum with the crossover sign in the left hip and a normal (anteverted) acetabulum in the right hip. In the normal right hip, the edge of the posterior wall (dotted line) may be at, or even lateral to, the center of the femoral head. In the retroverted left hip, the anterior wall (bold line) is lateral to the posterior wall at the most proximal aspect of the acetabulum (crossover sign) and the posterior wall is medial to the center of the femoral head (posterior wall sign).

Fig. 3: Fig. 3-B and Fig. 3-C Fig. 3-B Anteroposterior hip radiograph showing a normal (anteverted) acetabulum, with the red arrow pointing to the anterior wall and the yellow arrow pointing to the posterior wall (Reproduced, with modification, from: Reynolds D, Lucas J, Klaue K. Retroversion of the acetabulum. A cause of hip pain. J Bone Joint Surg Br. 1999;81:285. Reprinted with permission and copyright © of the British Editorial Society of Bone and Joint Surgery.) Fig. 3-C Anteroposterior hip radiograph showing a retroverted acetabulum, with the red arrow pointing to the anterior wall and the yellow arrow pointing to the posterior wall, demonstrating the crossover sign. (Reproduced, with modification, from: Reynolds D, Lucas J, Klaue K. Retroversion of the acetabulum. A cause of hip pain. J Bone Joint Surg Br. 1999;81:285. Reprinted with permission and copyright © of the British Editorial Society of Bone and Joint Surgery.)

A gadolinium-enhanced magnetic resonance arthrogram is needed to assess labral injury and the articular cartilage as well as to demonstrate the contour of the femoral head-neck junction^{7,9,15,16,35,44-46}. In one study, the sensitivity of magnetic resonance arthrography in detecting labral hypertrophy, degeneration, and/or tears was between 63% and 90%, while specificity was >70% when only labral tears were present¹⁶. (The specificity is poor for detecting chondral separations that remain undetached^7,44.) Measurements made on computed tomography or magnetic resonance imaging scans can suggest impingement^{9,15-17,35,43-46}. Kassarjian et al.⁴⁵, using magnetic resonance arthrography, defined a triad of anomalies in 88% of patients with cam impingement: an abnormal head-neck morphology, anterosuperior cartilage abnormality, and anterosuperior labral abnormality. In addition, dynamic magnetic resonance imaging with an open or large-bore unit can provide real-time imaging of the impingement³⁵.

	Treatment Options

Top Introduction Origin of Impingement Biomechanics of Impingement Clinical Features of... Imaging Studies Treatment Options References

 
Nonoperative Treatment
The goal of treatment is relief of the impingement. An initial trial of nonoperative treatment has been recommended by some authors^{7,11,38,44,47}. This may include modification of activity; restriction of athletic pursuits; and reduction of excessive motion of, and demand on, the hip. Nonsteroidal anti-inflammatory medication may relieve pain, but it may also mask symptoms. Physical therapy should emphasize muscle-strengthening and avoidance of extremes of range of motion. The young age of these patients means that they have a high activity level and athletic ambitions, which usually jeopardize compliance with nonoperative treatment.

Hip impingement is a mechanical problem, and nonoperative measures will not eliminate the pathomechanics of structural deformities^1,47. Jäger et al.³⁸ recommended an operation in patients with symptoms that persist beyond six months, provided that the articular damage is not severe. In their study, all nine patients who underwent nonoperative treatment had continued pain and hip dysfunction whereas six patients treated with an open osteoplasty all rated the hip as excellent or good and had resolution of the clinical symptoms. There seems to be little place for nonoperative treatment except when the cause is overuse without structural deformity.

Operative Treatment
Chronicity of signs and symptoms along with radiographic evidence of impingement and chondral and/or labral lesions are clear indications for operative intervention^7,38,44. When there is damage to the articular cartilage it is permanent and may compromise the result of operative treatment. Operative treatment focuses on improving the clearance of hip motion and alleviating femoral abutment against the acetabular rim, which will relieve the pathologic changes in the labrum and the articular cartilage. The three choices of treatment are arthroscopy, arthroscopy combined with a limited open operation, and an open operation with surgical dislocation of the hip. The operative treatment is chosen according to the specific disease pattern being corrected and the technical preferences and treatment philosophy of the surgeon. Open operative treatment is the original and best documented method for treatment of femoroacetabular impingement⁶, and it is the standard against which other joint-preserving treatment methods must be measured.

Arthroscopy
Usually, arthroscopy is indicated during the earlier stage of the disease^47-49. Clohisy and McClure stated that they preferred to perform arthroscopy initially to inspect the hip and determine the severity of the disease and to address the labral and chondral lesions³⁶; when they found localized disease, they performed a limited open resection osteoplasty without dislocating the joint. However, if the disease is extensive or global or there are posterior hip impingement lesions, surgical dislocation of the hip is necessary because it provides circumferential exposure and access to the entire acetabulum and proximal part of the femur^6,7.

The most common use for this minimally invasive treatment option is assessment and reconstruction of a nonspherical femoral head with a decreased head-neck offset^44,47-49. Associated labral and chondral lesions are treated in the hope of restoring nearly normal mechanics of the hip joint during the extremes of motion⁴⁷. The technique separates the hip into two compartments, central and peripheral. The central compartment includes the weight-bearing part of the head, the articular cartilage of the head, the acetabular fossa, and the ligamentum teres. The peripheral compartment contains the non-weight-bearing portions of the femoral head, the femoral neck, the hip capsule, synovial folds, and the orbicular ligaments. Access to the anterolateral aspect of the neck is through the peripheral compartment, and visualization of the labrum is through the central compartment⁴⁷. Labral lesions and any areas of chondral damage can be addressed, and labral tears can be repaired. Labral resection should be conservative, and attempts should be made to leave a stable labral remnant. In areas of exposed subchondral bone, a microfracture technique, chondroplasty, or drilling may be performed to stimulate a fibrocartilaginous response^47-49, although we are not aware of any reports of the clinical outcomes of these techniques in hips with impingement. Osteophytes on the femoral head or neck may be resected with a power burr or a radiothermal device to restore the concavity of the femoral head-neck junction. To avoid injury to the branches of the medial circumflex vessels, the distal and posterior extent of the procedure should be limited on the femoral neck to the area of impingement, typically about 10 mm from the articular margin⁴⁷. A concomitant excision of the anterior part of the acetabular rim is indicated when that part of the rim contributes to the impingement.

Fig. 4: Figs. 4-A and 4-B Illustrations of the right hip with the patient in the lateral position. (Reproduced, with modification, from: Ganz R, Gill TJ, Gautier E, Ganz K, Krügel N, Berlemann U. Surgical dislocation of the adult hip. A technique with full access to the femoral head and acetabulum without the risk of osteonecrosis. J Bone Joint Surg Br. 2001;83:1120. Reprinted with permission and copyright © of the British Editorial Society of Bone and Joint Surgery.) Fig. 4-A The osteotomy (outlined by the dark dashed line), along with the surrounding muscles. Fig. 4-B Drill holes have been placed, the osteotomy has been performed, and the greater trochanter has been mobilized anteriorly, exposing the capsule of the joint.

The results of arthroscopic surgery reported to date have been short-term, and we have no knowledge of the ability of this operative technique to alter the course toward total hip arthroplasty. Of 156 patients (age range, fourteen to seventy-three years) who had been treated with arthroscopy, 50% stated that the pain had resolved by three months; 75%, by five months; and 95%, by one year⁴⁹. During that time, three patients required a total hip arthroplasty, and these failures correlated with the amount of articular cartilage damage noted at arthroscopy. Similarly, Guanche and Bare⁴⁷ found that their results correlated with the presence of degenerative cartilage changes. The advocates for arthroscopic surgery have suggested that the results will be comparable with those reported following open operations, but the patients recover much earlier after arthroscopic surgery^44,49; however, most arthroscopically treated patients have early-stage disease.

Hybrid Arthroscopy and Open Procedures
Arthroscopy with a limited open osteochondroplasty is advocated for the treatment of focal cam impingement. The potential advantage is that it is less invasive than surgical dislocation, and it may reduce complications while enabling quicker recovery³⁶. This approach was developed because of concerns that arthroscopy would provide inadequate exposure of the head-neck junction, create the potential for osseous debris to become entrapped in the joint, and provide an inadequate osseous reconstruction. Arthroscopy can allow treatment of labral disease at the acetabular margin and any associated chondral damage. The limited open procedure, with use of the Smith-Petersen interval and without dislocation of the hip, is difficult except in thin patients, and we are not aware of any published reports of clinical outcomes. Exposure of the anterolateral head-neck junction and the anterolateral aspect of the acetabular rim allows osteoplasty at these sites. This procedure is not advocated for hips with posterior impingement or circumferential lesions of the femoral head. The postoperative treatment is similar to that described following arthroscopy³⁶.

Open Procedures
Operative reconstruction as joint-preserving surgery has been recommended for osteoarthritis that is no worse than grade 1^2,50. Advanced degenerative changes and extensive chondral lesions have not responded well to open débridement, with high rates of progression and conversion to a total hip arthroplasty^2,25. Patients who have a structural problem that cannot be corrected with this technique are not candidates, and it may be relatively contraindicated in elderly patients, depending on the severity of symptoms and presence of secondary arthritic changes⁵¹. In their original report, Ganz et al.⁶ stated that they made an intraoperative decision to perform a total hip arthroplasty in patients with advanced chondral lesions. Patients with migration of the femoral head into the acetabular cartilage defect at the time of evaluation may benefit from surgery in the short term, but ongoing degeneration of the hip has to be expected¹¹.

Open procedures have been performed with a posterior incision made from the posterior-superior edge of the greater trochanter distally to the posterior border of the vastus lateralis ridge^6,52. After placement of drill holes for later reattachment, a trochanteric flip osteotomy (or a trigastric osteotomy with the gluteus medius, vastus lateralis, and gluteus minimus remaining attached to the trochanteric fragment) is performed⁶. The osteotomy consists of a horizontal cut with the leg internally rotated. It has a maximum thickness of 1.5 to 2.0 cm at its proximal limit^6,52. The osteotomy (Figs. 4-A and 4-B) must be anterior to the most posterior insertion of the gluteus medius tendon and should exit superficial to the piriformis fossa superiorly. At the vastus ridge distally, the integrity of the external rotator muscles is respected, with preservation and protection of the profundus branch of the medial circumflex femoral artery, which becomes intracapsular at the level of the superior gemellus muscle⁵³. It is also necessary to protect the epiphyseal branches of the medial circumflex femoral artery, which lie subperiosteally on the posterior-superior surface of the femoral neck. It must be remembered that the blood supply to the femoral head arises mainly from the medial circumflex femoral artery, and during dislocation of the hip this vessel is protected by the intact obturator externus muscle^6,7,53. Some surgeons prefer to assess the sciatic nerve to determine if it bifurcates over the belly of the piriformis, and, if it does, the piriformis is released to prevent traction injury to the more superficial branch during hip dislocation.

Capsular incision: The capsule is incised anterolaterally along the axis of the femoral neck. The capsulotomy must remain anterior to the lesser trochanter to avoid damage to the main branch of the medial circumflex femoral artery, which lies just superior and posterior to the lesser trochanter. Elevation of the anteroinferior capsular flap allows visualization of the acetabular labrum. The first capsular incision is then extended toward the acetabular rim, where it is sharply turned posteriorly, parallel to the labrum, reaching the retracted tendon of the piriformis (completing the z-shaped capsulotomy for the right hip⁶ [Fig. 5] and an inverse z-shaped capsulectomy for the left hip). Alternatively, a T-shaped capsulotomy may be done⁵².

Fig. 5: The z-shaped capsulotomy for the right hip. The longitudinal limb (A) is parallel to the femoral neck axis and is continued in line with the anterior intertrochanteric crest (B). The distal transverse limb is directed anteriorly and medially at the base of the neck toward the calcar (C). A cuff of capsular tissue is left on the inferior aspect of the neck for later reattachment (D). The proximal transverse limb is formed by incising the capsule posteriorly along the superior aspect of the acetabular rim until the piriformis is reached (E). (Reproduced, with modification, from: Ganz R, Gill TJ, Gautier E, Ganz K, Krügel N, Berlemann U. Surgical dislocation of the adult hip. A technique with full access to the femoral head and acetabulum without the risk of osteonecrosis. J Bone Joint Surg Br. 2001;83:1121. Reprinted with permission and copyright © of the British Editorial Society of Bone and Joint Surgery.)

Some authors have used other approaches for localized or less extensive lesions^25,38. The direct lateral exposure can be chosen for hips in which less exposure of the posterior-inferior aspect of the acetabulum is required, and the iliofemoral exposure may be chosen for hips with pure anterior impingement. However, global visualization and comprehensive deformity correction on both sides of the joint are best obtained with the trochanteric flip operation⁶. All approaches that retain an intact greater trochanter are associated with greater difficulty in separating and mobilizing the gluteus minimus from its attachment to the capsule, since the tip of the greater trochanter overlies the most critical part of its insertion⁶.

Treatment Options for the Lesions Seen with Impingement
Osteoplasty of the Femoral Neck
To avoid lateral retinacular vessels on the posterolateral aspect of the femoral neck, the osteotome used for the osteoplasty should be oriented perpendicular to the cartilage plane and small pieces of bone should be fractured gently by prying distally on the fragment¹¹. The pieces of bone are sharply dissected free of retinacular attachment with a scalpel. Studies of cadavera have shown that the total amount of bone resected should not exceed 30% of the anterolateral quadrant of the head-neck junction to minimize the risk of femoral neck fracture⁵¹. Resection of approximately 20% of the head-neck diameter has been found to be satisfactory for optimizing hip flexion without impingement⁵². Before capsular closure, the cartilage edge on the femoral head, created by the osteotome, is smoothed with a scalpel, and bone wax is applied to the bleeding surface¹¹.

This review has not focused on extra-articular impingement, but it should be noted that reorientation of the proximal part of the femur with a flexion-valgus intertrochanteric osteotomy can be done to reduce extra-articular impingement caused by decreased femoral anteversion or a varus position of the neck^6,11. Relative neck lengthening through trochanteric advancement is another option for increasing clearance and alleviating the extra-articular impingement to optimize hip abduction⁷.

Acetabular Osteotomy
The prominent anterior aspect of the acetabular rim can be removed by resection osteoplasty or by reorientation of the retroverted acetabulum¹¹. The acetabular depth, in particular the posterior wall, and the status of the acetabular articular cartilage determine which option should be chosen. If the acetabulum is retroverted, it can be internally rotated and flexed through a periacetabular osteotomy. Siebenrock et al.²⁰ reported good or excellent results in twenty-six (90%) of twenty-nine hips treated with this procedure⁵⁵; however, it can produce an excessively prominent posterior wall and cause secondary posterior impingement. Conversely, a reverse periacetabular osteotomy may be preferred if the acetabular articular cartilage is intact, but there is a lack of posterior coverage^7,11. The anatomy of the posterior wall is best assessed on an anteroposterior pelvic radiograph on the basis of the posterior wall sign^20,34.

Simple rim osteoplasty and labral repair can be done after dislocation of the hip. Identified labral and chondral lesions are tested, with use of a nerve hook, for partial or complete avulsions from the acetabular rim¹¹. In cases of anterior overcoverage, a resection osteoplasty of the anterosuperior aspect of the rim is done after mobilization of the acetabular labrum. Resection of the labrum (limited to the injured area) is done when it is ossified or when excessive scarring, attrition, or degeneration of the labrum is seen. The amount of rim resection can be estimated after reduction of the head and evaluation of the impingement. The labrum is then reattached to the acetabular rim with anchored sutures. The hip is reduced, and the stability of labral fixation and the resolution of impingement are confirmed. In a retrospective study of matched cohorts, Espinosa et al.⁵ found that thirty-two patients treated with labral refixation recovered earlier and had superior clinical and radiographic results at one and two years when compared with twenty patients who had undergone resection of the torn labrum.

Postoperative Rehabilitation and Pattern of Recovery
The hospital stay ranges from two to four days. To prevent adhesions between the capsule and the site of the femoral osteoplasty, a continuous-passive-motion device is used for the first postoperative week¹¹. Protected weight-bearing and limitation of flexion to 70° are continued for eight weeks, after which the patient begins self-administered abduction exercises as well as swimming (except for the breast stroke) and bicycling. At three to six months, the patient may be allowed to resume all activities of normal living. Ganz et al.⁵⁵ did not recommend starting or continuing with high-impact or stop-and-go sports. Joint-preserving surgery does not provide a perfectly normal joint, and high-impact sports can cause the operation to fail.

Clinical Outcomes
Osteonecrosis has not been reported, to our knowledge, after open reconstruction involving dislocation^2,6,25,26,38. Ganz et al.⁶ performed 213 surgical dislocations, including twenty-four with an additional intertrochanteric osteotomy. They did not include hips that had been converted intraoperatively to a total hip replacement in their report. Three hips (1.4%) required a reoperation because of trochanteric nonunion, and heterotopic ossification developed in seventy-nine hips (37%). Most patients had an improvement in the range of motion and a decrease in pain, although these results were not specifically discussed. In a study by Murphy et al.²⁵, seven (30%) of twenty-three hips treated with débridement because of femoroacetabular impingement were converted to a total hip arthroplasty and one had subsequent arthroscopic débridement of a recurrent labral tear. Beck et al.² reported that fourteen of nineteen patients had an excellent or good result at a mean of 4.7 years after surgical treatment of femoroacetabular impingement, whereas five required a total hip arthroplasty.

Although long-term analyses of the outcomes of surgical intervention are not available, the preliminary results indicate that surgical dislocation of the hip to allow improvement in the head-neck offset, as well as rim osteoplasty, is successful in alleviating the symptoms of impingement in most patients. It is important that the treatment, particularly realignment osteotomies of the acetabulum and proximal part of the femur, do not result in secondary impingement. Although early correction of impingement has improved hip function, it is not yet known how often the correction prevents the progression of osteoarthritis.

	Acknowledgments

 
NOTE: The authors appreciate the suggestions and advice of Reinholz Ganz, MD, in the preparation of this manuscript.

	References

Top Introduction Origin of Impingement Biomechanics of Impingement Clinical Features of... Imaging Studies Treatment Options References

 

1. Beck M, Kalhor M, Leunig M, Ganz R. Hip morphology influences the pattern of damage to the acetabular cartilage: femoroacetabular impingement as a cause of early osteoarthritis of the hip.J Bone Joint Surg Br .2005; 87:1012 -8.[CrossRef][Medline]

2. Beck M, Leunig M, Parvizi J, Boutier V, Wyss D, Ganz R. Anterior femoroacetabular impingement: part II. Midterm results of surgical treatment. Clin Orthop Relat Res.2004 :418:67 -73.[Medline]

3. Eijer H, Myers SR, Ganz R. Anterior femoroacetabular impingement after femoral neck fractures. J Orthop Trauma. 2001;15:475 -81.[CrossRef][Medline]

4. Eijer H, Leunig M, Mahomed N, Ganz R. Cross-table lateral radiographs for screening of anterior femoral head-neck offset in patients with femoroacetabular impingement. Hip Int.2001; 11:37 -41.

5. Espinosa N, Rothenfluh DA, Beck M, Ganz R, Leunig M. Treatment of femoroacetabular impingement: preliminary results of labral refixation. J Bone Joint Surg Am.2006; 88:925 -35.[Abstract/Free Full Text]

6. Ganz R, Gill TJ, Gautier E, Ganz K, Krügel N, Berlemann U. Surgical dislocation of the adult hip. A technique with full access to the femoral head and acetabulum without the risk of avascular necrosis. J Bone Joint Surg Br.2001; 83:1119 -24.[CrossRef][Medline]

7. Ganz R, Parvizi J, Beck M, Leunig M, Nötzli H, Siebenrock KA. Femoroacetabular impingement: a cause for osteoarthritis of the hip. Clin Orthop Relat Res.2003; 417:112 -20.[Medline]

8. Ito K, Leunig M, Ganz R. Histopathologic features of the acetabular labrum in femoroacetabular impingement. Clin Orthop Relat Res. 2004;429:262 -71.[CrossRef][Medline]

9. Ito K, Minka MA, Leunig M, Werlen S, Ganz R. Femoroacetabular impingement and the cam-effect. A MRI-based quantitative anatomical study of the femoral head-neck offset. J Bone Joint Surg Br. 2001;83:171 -6.[CrossRef][Medline]

10. Klaue K, Durnin CW, Ganz R. The acetabular rim syndrome. A clinical presentation of dysplasia of the hip.J Bone Joint Surg Br .1991; 73:423 -9.[Medline]

11. Lavigne M, Parvizi J, Beck M, Siebenrock KA, Ganz R, Leunig M. Anterior femoroacetabular impingement: part I. Techniques of joint preserving surgery. Clin Orthop Relat Res.2004; 418:61 -6.[Medline]

12. Leunig M, Beck M, Dora C, Ganz R. [Femoroacetabular impingement: trigger for the development of coxarthrosis].Orthopade . 2006;35:77 -84. German.[CrossRef][Medline]

13. Leunig M, Beck M, Kalhor M, Kim YJ, Werlen S, Ganz R. Fibrocystic changes at anterosuperior femoral neck: prevalence in hips with femoroacetabular impingement.Radiology . 2005;236:237 -46.[Abstract/Free Full Text]

14. Leunig M, Beck M, Woo A, Dora C, Kerboull M, Ganz R. Acetabular rim degeneration: a constant finding in the aged hip. Clin Orthop Relat Res.2003; 413:201 -7.[CrossRef][Medline]

15. Leunig M, Podeszwa D, Beck M, Werlen S, Ganz R. Magnetic resonance arthrography of labral disorders in hips with dysplasia and impingement. Clin Orthop Relat Res.2004; 418:74 -80.[CrossRef][Medline]

16. Leunig M, Werlen S, Ungersböck A, Ito K, Ganz R. Evaluation of the acetabular labrum by MR arthrography.J Bone Joint Surg Br .1997; 79:230 -4.[CrossRef][Medline]

17. Meyer DC, Beck M, Ellis T, Ganz R, Leunig M. Comparison of six radiographic projections to assess femoral head/neck asphericity. Clin Orthop Relat Res.2006; 445:181 -5.[Medline]

18. Myers SR, Eijer H, Ganz R. Anterior femoroacetabular impingement after periacetabular osteotomy. Clin Orthop Relat Res. 1999;363:93 -9.[Medline]

19. Siebenrock KA, Ganz R. Osteochondroma of the femoral neck. Clin Orthop Relat Res.2002; 394:211 -8.[CrossRef][Medline]

20. Siebenrock KA, Schoeniger R, Ganz R. Anterior femoro-acetabular impingement due to acetabular retroversion. Treatment with periacetabular osteotomy. J Bone Joint Surg Am.2003; 85:278 -86.[Abstract/Free Full Text]

21. Siebenrock KA, Wahab KH, Werlen S, Kalhor M, Leunig M, Ganz R. Abnormal extension of the femoral head epiphysis as a cause of cam impingement. Clin Orthop Relat Res.2004; 418:54 -60.[CrossRef][Medline]

22. Wagner S, Hofstetter W, Chiquet M, Mainil-Varlet P, Stauffer E, Ganz R, Siebenrock KA. Early osteoarthritic changes of human femoral head cartilage subsequent to femoro-acetabular impingement. Osteoarthritis Cartilage.2003; 11:508 -18.[CrossRef][Medline]

23. Murray RO. The aetiology of primary osteoarthritis of the hip. Br J Radiol.1965; 38:810 -24.[Abstract/Free Full Text]

24. Stulberg SD, Cordell LD, Harris WH, Ramsey PL, MacEwen GD. Unrecognized childhood hip disease: a major cause of idiopathic osteoarthritis of the hip. In: The Hip. Proceedings of the Third Open Scientific Meeting of the Hip Society. St Louis, MO: CV Mosby; 1975. p 212-28.

25. Murphy S, Tannast M, Kim YJ, Buly R, Millis MB. Debridement of the adult hip for femoroacetabular impingement: indications and preliminary clinical results. Clin Orthop Relat Res. 2004;429:178 -81.[CrossRef][Medline]

26. Tanzer M, Noiseux N. Osseous abnormalities and early osteoarthritis: the role of hip impingement.Clin Orthop Relat Res .2004; 429:170 -7.[CrossRef][Medline]

27. Pitkow RB. External rotation contracture of the extended hip. A common phenomenon of infancy obscuring femoral neck anteversion and the most frequent cause of out-toeing gait in children.Clin Orthop Relat Res .1975; 110:139 -45.[CrossRef][Medline]

28. Tönnis D, Heinecke A. Acetabular and femoral anteversion: relationship with osteoarthritis of the hip. J Bone Joint Surg Am. 1999;81:1747 -70.[Free Full Text]

29. Watanabe RS. Embryology of the human hip. Clin Orthop Relat Res.1974; 98:8 -26.[CrossRef][Medline]

30. Giori NJ, Trousdale RT. Acetabular retroversion is associated with osteoarthritis of the hip. Clin Orthop Relat Res. 2003;417:263 -9.[Medline]

31. McKibbin B. Anatomical factors in the stability of the hip joint in the newborn. J Bone Joint Surg Br. 1970;52:148 -59.[Medline]

32. Kim WY, Hutchinson CE, Andrew JG, Allen PD. The relationship between acetabular retroversion and osteoarthritis of the hip. J Bone Joint Surg Br.2006; 88:727 -9.[CrossRef][Medline]

33. Li PL, Ganz R. Morphologic features of congenital acetabular dysplasia: one in six is retroverted. Clin Orthop Relat Res. 2003;416:245 -53.[CrossRef][Medline]

34. Reynolds D, Lucas J, Klaue K. Retroversion of the acetabulum. A cause of hip pain. J Bone Joint Surg Br. 1999;81:281 -8.[CrossRef][Medline]

35. Beall DP, Sweet CF, Martin HD, Lastine CL, Grayson DE, Ly JQ, Fish JR. Imaging findings of femoroacetabular impingement syndrome. Skeletal Radiol.2005; 34:691 -701.[CrossRef][Medline]

36. Clohisy JC, McClure JT. Treatment of anterior femoroacetabular impingement with combined hip arthroscopy and limited anterior decompression. Iowa Orthop J.2005; 25:164 -71.[Medline]

37. Burnett RS, Della Rocca GJ, Prather H, Curry M, Maloney WJ, Clohisy JC. Clinical presentation of patients with tears of the acetabular labrum. J Bone Joint Surg Am.2006; 88:1448 -57.[Abstract/Free Full Text]

38. Jäger M, Wild A, Westhoff B, Krauspe R. Femoroacetabular impingement caused by a femoral osseous head-neck bump deformity: clinical, radiological, and experimental results. J Orthop Sci. 2004;9:256 -63.[CrossRef][Medline]

39. Murray DW. The definition and measurement of acetabular orientation. J Bone Joint Surg Br.1993; 75:228 -32.[Medline]

40. Harris WH. Etiology of osteoarthritis of the hip. Clin Orthop Relat Res.1986; 213:20 -33.[Medline]

41. Pitt MJ, Graham AR, Shipman JH, Birkby W. Herniation pit of the femoral neck. AJR Am J Roentgenol.1982; 138:1115 -21.[Abstract/Free Full Text]

42. Peelle MW, Della Rocca GJ, Maloney WJ, Curry MC, Clohisy JC. Acetabular and femoral radiographic abnormalities associated with labral tears. Clin Orthop Relat Res.2005; 441:327 -33.[CrossRef][Medline]

43. Beaulé PE, Zaragoza E, Motamedi K, Copelan N, Dorey FJ. Three-dimensional computed tomography of the hip in the assessment of femoroacetabular impingement. J Orthop Res.2005; 23:1286 -92.[Medline]

44. Crawford JR, Villar RN. Current concepts in the management of femoroacetabular impingement. J Bone Joint Surg Br. 2005;87:1459 -62.[CrossRef][Medline]

45. Kassarjian A, Yoon LS, Belzile E, Connolly SA, Millis MB, Palmer WE. Triad of MR arthrographic findings in patients with cam-type femoroacetabular impingement. Radiology.2005; 236:588 -92.[Abstract/Free Full Text]

46. Nötzli HP, Wyss TF, Stoecklin CH, Schmid MR, Treiber K, Hodler J. The contour of the femoral head-neck junction as a predictor for the risk of anterior impingement. J Bone Joint Surg Br. 2002;84:556 -60.[CrossRef][Medline]

47. Guanche CA, Bare AA. Arthroscopic treatment of femoroacetabular impingement. Arthroscopy.2006; 22:95 -106.[Medline]

48. McCarthy JC, Noble PC, Schuck MR, Wright J, Lee J. The role of labral lesions to development of early degenerative hip disease. Clin Orthop Relat Res.2001; 393:25 -37.[CrossRef][Medline]

49. Sampson TG. Arthroscopic treatment of femoroacetabular impingement. Tech Orthop.2005; 20:56 -62.[CrossRef]

50. Tönnis D. Normal values of the hip joint for the evaluation of X-rays in children and adults. Clin Orthop Relat Res. 1976;119:39 -47.[Medline]

51. Mardones RM, Gonzalez C, Chen Q, Zobitz M, Kaufman KR, Trousdale RT. Surgical treatment of femoroacetabular impingement: evaluation of the effect of the size of the resection. J Bone Joint Surg Am. 2005;87:273 -9.[Abstract/Free Full Text]

52. Mardones RM, Gonzalez C, Chen Q, Zobitz M, Kaufman KR, Trousdale RT. Surgical treatment of femoroacetabular impingement: evaluation of the effect of the size of the resection. Surgical technique. J Bone Joint Surg Am.2006; 88 Suppl 1 Pt 1:84 -91.[Abstract/Free Full Text]

53. Gautier E, Ganz K, Krügel N, Gill T, Ganz R. Anatomy of the medial femoral circumflex artery and its surgical implications. J Bone Joint Surg Br.2000; 82:679 -83.[CrossRef][Medline]

54. Nötzli HP, Siebenrock KA, Hempfing A, Ramseier LE, Ganz R. Perfusion of the femoral head during surgical dislocation of the hip. Monitoring by laser Doppler flowmetry. J Bone Joint Surg Br. 2002;84:300 -4.[CrossRef][Medline]

55. Ganz R, Klaue K, Vinh TS, Mast JW. A new periacetabular osteotomy for the treatment of hip dysplasias. Technique and preliminary results. Clin Orthop Relat Res.1988; 232:26 -36.[Medline]

CiteULike

Connotea

Del.icio.us

Facebook

Technorati

Twitter

This Article Extract Full Text (PDF) Free CME: Take the activities for this article: Adult Hip Reconstruction Test 27: Winter 2008 (publication date February 15... CME 4: October, November, December 2007 (publication date January 4, 2008; ... [FREE Spanish Translation] Letters to the Editor: Submit a response Letters to the Editor: View responses 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 Similar articles in PubMed 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 Google Scholar Google Scholar Articles by Maheshwari, A. V. Articles by Dorr, L. D. Search for Related Content PubMed PubMed Citation Articles by Maheshwari, A. V. Articles by Dorr, L. D. Related Collections Current Concepts Review Adult Hip Social Bookmarking                   What's this?

Stanford University Libraries' HighWire Press (TM) assists in the publication of JBJS Online.
Copyright © 2007 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.