 |
 |
 |
|
| home | CME | help | feedback | subscriptions | archive |
|
© 1999 The Journal of Bone and Joint Surgery, Inc. The Functional Outcome of Operative Treatment of Ununited Fractures of the Humeral Diaphysis in Older Patients*  , BOSTON, MASSACHUSETTSInvestigation performed at Massachusetts General Hospital, Boston
Twenty-two elderly patients (average age, seventy-two years) who had an atrophic, unstable, ununited fracture of the humeral diaphysis were managed with plate-and-screw fixation and application of an autogenous bone graft from the iliac crest. Fifteen of the patients had had at least one previous operation in an attempt to obtain union of the fracture. One patient had an active infection and two had a quiescent infection, all with Staphylococcus epidermidis. The average duration of nonunion before the patients were first seen by us was two years and four months (range, five months to sixteen years). Fifteen of the nonunions were synovial. In each patient, at least one modification of the standard technique of plate-and-screw fixation was needed as a result of osteopenia. In order to enhance fixation, the standard protocol incorporated the use of a long plate (with an average of eleven holes and an average length that was 76 percent of that of the bone), a plate with a blade (used in thirteen patients), and replacement of loose, 4.5-millimeter cortical-bone screws with 6.5-millimeter cancellous-bone screws (twelve patients). Spiked nuts (Schuhli nut; Synthes, Paoli, Pennsylvania) that lock the screws to the plate, creating a solid point of fixation analogous to a blade, were incorporated into the protocol when they became available (used in six patients). In five limbs, the nonunion was associated with an osseous defect that could not be addressed by shortening of the bone alone. Three of these limbs were stabilized with a bridge plate that had been contoured to stand away from the bone at the site of nonunion (so-called wave-plate osteosynthesis), and the remaining two limbs were stabilized with a combination of intramedullary and extramedullary plates. In one of these two limbs, the extramedullary plate was contoured (that is, a wave plate). The fracture united in twenty (91 percent) of the patients. There was no progressive loosening or breakage of a fixation device, even in two patients who had radiographs that were suggestive of an incomplete union. Five of the patients were followed for a limited duration (average, one year and six months) as a result of death or illness. They had two excellent results, two good results, and one poor result according to a modification of the rating system of Constant and Murley. The remaining seventeen patients, including the two who had a persistent nonunion, were followed for an average of three years and one month (range, two years to five years and ten months). They had significant improvements in all of the functional scores at the most recent follow-up evaluation: the average score according to the modified system of Constant and Murley increased from 9 to 72 points (p < 0.001), the average score according to the Enforced Social Dependency Scale decreased from 39 to 9 points (p < 0.001), and the average score based on the Disabilities of the Arm, Shoulder, and Hand Questionnaire decreased from 77 to 24 points (p < 0.001). According to the scores based on the Disabilities of the Arm, Shoulder, and Hand Questionnaire, nine of the seventeen patients who had been followed for more than two years had an excellent result, four had a good result, two had a fair result, and the two who had a persistent nonunion had a poor result. Complications included postoperative delirium, a stitch abscess, transient radial nerve palsy, a fracture distal to the plate, and the need for a blood transfusion, in one patient each. Two patients had a fibrous union. There were no major medical complications. An unstable, united fracture of the humeral diaphysis can be extremely disabling and may threaten the ability of an elderly patient to function independently. Operative treatment can be very successful when the techniques of plate-and-screw fixation are modified to address osteopenia and relative or absolute loss of bone. Healing of the fracture substantially improves function and the degree of independence.
The belief is prevalent that, unlike ununited diaphyseal fractures in the lower extremity, which are disabling, nonunions in the upper extremity are often compatible with acceptable function, particularly in elderly patients who have decreased functional demands11,39,41. This belief should be questioned because elderly individuals are often less capable of adapting to musculoskeletal dysfunction6,24,44. Elderly patients depend on an intact musculoskeletal system to maintain function and independence in activities of daily living44. Improvements in the ability to obtain stable fixation in poor-quality, osteopenic bone10,18,20,22,30,37,40,43 have reinforced our policy of offering operative treatment to elderly patients who have an unstable, ununited fracture of the upper extremity that affects the quality of life. This investigation represents our efforts, with the use of objective scoring systems and patient-oriented outcome instruments, to quantify improvements in function and the degree of independence after operative treatment of ununited fractures of the humerus in older patients.
The criteria for inclusion in the present study were a mobile, unstable nonunion of the humeral diaphysis that had been present for at least five months after the initial injury, an age of sixty years or older, and osteopenia that would jeopardize standard plate-and-screw fixation. Between December 1990 and June 1996, twenty-five patients met the criteria in the referral practice of one of us (J. B. J.). Twenty-two of these patients requested operative intervention. The average age of the twenty-two patients was seventy-two years (range, sixty to eighty-five years). Eleven patients had one or more major comorbid diseases: six had coronary artery disease; three, congestive heart failure; four, diabetes mellitus; two, chronic obstructive pulmonary disease; two, peripheral vascular disease; and one each, end-stage renal disease, rheumatoid arthritis, Parkinson disease, senile dementia, cirrhosis, cerebrovascular disease, and breast cancer. Four patients were employed outside of the home at the time of the injury, and eighteen either were retired or were homemakers. The initial fracture resulted from a fall from a standing height (eighteen patients), a motor-vehicle accident (three), or a fall from a roof (one). The right arm was involved in thirteen patients and the left arm, in nine. The dominant arm was involved in fifteen patients. The proximal third of the humeral diaphysis was affected in fourteen patients; the middle third, in five; the distal third, in two; and both the proximal and the middle third (a segmental fracture), in one. In one patient, the fracture occurred at the distal end of a shoulder prosthesis. The initial treatment was nonoperative for twelve patients: a hanging cast was used for five patients, a polypropylene brace was used for five, and a sling was used for two. In ten patients, the initial treatment was operative: plate-and-screw fixation was used in four patients, antegrade insertion of an intramedullary Rush rod was used in three, antegrade insertion of a locking intramedullary rod was used in two (with ancillary cerclage wiring in one), and a custom-made, extra-long stem was used to replace the humeral component of the total shoulder prosthesis in the patient who had a periprosthetic fracture. Fifteen patients had one, two, or three operations after the initial treatment in an attempt to obtain union. The fixation device had either loosened or broken, or both, in all fifteen patients. At the time of the initial visit to our office, seven patients had an intramedullary device, six had a plate, and two had had the implant removed. When first seen by us, one patient had an active infection and two had a quiescent infection, all with Staphylococcus epidermidis. The active infection was treated with serial débridement, temporary external fixation, and parenteral administration of antibiotics before definitive plate fixation. The patient who had had a fracture distal to the humeral component of a shoulder prosthesis had an infection after two subsequent operations: the first was a conversion of the humeral stem to a long-stem prosthesis that bridged the fracture site, and the second was the addition of bone graft obtained from the iliac crest. This patient came to our office after removal of the prosthesis and serial débridement with a resection arthroplasty of the shoulder and an antibiotic-impregnated polymethylmethacrylate spacer at the site of nonunion. In each patient, the nonunion was unstable, had no sign of healing, and was defined as atrophic according to the criteria of Weber and Cech49. In fifteen patients, the nonunion was defined as a synovial pseudarthrosis on the basis of the intraoperative finding of a fluid-filled, synovial-lined cavity at the site of nonunion. The average duration from the time of the injury to the index procedure was two years and four months (range, five months to sixteen years). All twenty-two patients reported severe functional disability of the involved extremity due to pain and instability at the site of nonunion. At the time of the initial evaluation, most of the patients were wearing a sling or a brace, or both. Eight patients who had been advised by their surgeon that nothing additional could be done to obtain an osseous union came to our office on their own.
Operative Technique An attempt was made to limit dissection of the soft tissues to the area required for application of the plate and for débridement of the site of the synovial nonunion. Every attempt was made to leave the periosteum in place. Circumferential reduction clamps were not used, and a distractor was employed to facilitate realignment of the bone segments29. All inflammatory, fibrous, and synovial tissue and sclerotic and avascular bone were debrided. When the bone ends were sclerotic, the intramedullary canal of each fragment was opened with the use of a power drill. Autogenous cancellous bone graft obtained from the iliac crest was used in all of the patients. The specific method of skeletal fixation was chosen on the basis of the previous operative procedure, the quality of the bone, and the presence of relative or absolute bone loss. The operative technique was based on the principle that every effort should be made to counteract the effects of osteopenia, either due to osteoporosis or secondary to the fracture, that would jeopardize the stability and rigidity of the plate-and-screw fixation. A long plate was used to increase the number of sites of fixation and to decrease the possibility of a fracture distal to the plate. The recommendation for the longer plate is based on the principle that an intramedullary rod should span the length of the humerus in order to enhance the stability of fixation and to decrease the risk of a fracture proximal and distal to the implant23. We elected not to use an intramedullary rod because all of the patients had an atrophic or synovial nonunion and needed débridement and bone-grafting. A broad, 4.5-millimeter dynamic compression plate was used in eight patients, six of whom were managed with a titanium limited-contact design (Synthes, Paoli, Pennsylvania). Six patients were managed with a narrow, 4.5-millimeter titanium limited-contact dynamic compression plate (Synthes), which had been modified into a blade-plate for five of them. A titanium blade-plate (Synthes) designed specifically for the proximal aspect of the humerus was used in eight patients. The plates had an average of eleven holes (range, nine to fourteen holes), and the average ratio of the length of the plate to the length of the entire bone was 76 percent (range, 55 to 90 percent). In one of the patients who had a nonunion of the distal aspect of the humerus, an additional eight-hole, 3.5-millimeter limited-contact dynamic compression plate (Synthes) was placed over the posterior surface of the humerus. Another principle was to use, when necessary, a blade-plate to enhance fixation (Figs. 1-A, 1-B, 1-C, 1-D, 1-E, 2-A, 2-B, 2-C, 2-D, 2-E, 3-A, 3-B, 3-C, 3-D, 3-E, 3-F). Of the thirteen patients in whom a blade-plate was used, nine had a nonunion in the proximal third of the humeral diaphysis (fourteen patients had a fracture at this level in the series as a whole); two, in the middle third of the diaphysis (five patients had a fracture at this level in the series as a whole); one, in the distal third of the diaphysis (two patients had a fracture at this level in the series as a whole); and one, in the proximal and middle thirds of the diaphysis. The blade acts as a broad, stable point of fixation in metaphyseal bone, which is not dependent on thread-bone purchase. Of the eight patients in whom a blade-plate designed specifically for internal fixation of the humerus was used18, one had insertion of the blade into the distal metaphysis and seven had insertion into the proximal metaphysis. In the five patients who had a modification of a narrow, 4.5-millimeter limited-contact dynamic compression plate, the proximal end of the plate was bent to a 90-degree angle and was impacted into the proximal humeral metaphysis.
The final principle was related to the enhancement of screw-bone purchase. It is necessary to be aware that the holding power of a screw is directly proportional to the density of the bone in which it is placed46 and that, if the screw loosens, it will no longer stabilize the fracture23. Initially, 4.5-millimeter cortical-bone screws that loosened immediately after insertion either were reinforced with polymethylmethacrylate35,42 (two patients) or were replaced with 6.5-millimeter cancellous-bone screws (twelve patients). In one of the first patients in the series, an allograft strut was placed on the medial surface of the humerus to enhance fixation of the screws5,8,9. However, this technique was later abandoned because of concerns regarding the extent of muscle elevation and the resulting devascularization of bone. When Schuhli nuts (Synthes) became available, we used them (in six patients) to enhance the stability of screw fixation in osteopenic bone20,22,23,30,31. The Schuhli nut fits into a standard screw-hole from the underside of the plate. A standard screw inserted over a washer is then threaded into the Schuhli washer and is tightened so that the screw, washer, and Schuhli nut are attached rigidly to the plate, creating a rigid point of fixation analogous to the blade of a blade-plate. Screws that are fixed rigidly to the plate depend less on thread-bone purchase for stability22. Schuhli nuts have two-millimeter-long spikes on the undersurface that further enhance fixation of the screw-plate-nut construct in the bone. In addition, these spiked nuts increase the space between the plate and bone and further limit the area of bone that is covered by the internal fixation device, thereby increasing the area of contact between the vascularized soft tissues and bone20,30. After removal of loose hardware and débridement of avascular bone, five patients had an osseous defect that could not be corrected by skeletal shortening. The average length of the defect was three centimeters (range, two to six centimeters). The osseous defect was treated with a bridge plate that was contoured to stand away from the bone at the site of the defect (so-called wave-plate osteosynthesis) in four patients2,3,35,37,38,50. One of these patients as well as another patient had a combination of intramedullary and extramedullary plates10,29,30. The latter technique enhances the stability of internal fixation by substituting an intramedullary plate for the absent cortex opposite the extramedullary plate. Some screws pass through the holes in both plates, whereas others serve to buttress the plate against the far cortex. Compared with standard plates, this construct may enhance the ability of the bone to resist a variety of forces that are present at the site of the segmental defect10,30. A small-fragment (3.5-millimeter) dynamic compression plate, equal in length to an eight or fourteen-hole plate, was used in the intramedullary space in the two patients who were managed with this technique. Screw fixation was enhanced by the application of an intramedullary fibular allograft strut in one of the patients who had so-called wave-plate osteosynthesis.
Postoperative Management
Evaluation of Preoperative and Postoperative Status
Enforced Social Dependency Scale Enforced social dependency is essentially equivalent to functional status. It is a response to the current situation, not an inherent characteristic of the patient. There are two components in this scale. The first component, personal competence, is the ability to perform activities that are central to functioning as a normal adult; these include eating, dressing, bathing, toileting, walking, and traveling. The level of dependency in each activity is rated on a 6-point scale, with higher ratings reflecting greater dependency. The second component, social competence, is the ability to perform tasks related to a job, housework, and recreation. The level of dependency in each activity is rated on a 4-point scale. In addition, the coherence of the patient's responses is rated on a 3-point scale. Each item is assessed with the use of an interview-based questionnaire, which has been used most commonly to evaluate patients who have cancer or other medical illnesses36,51. According to the Enforced Social Dependency Scale, 10 points indicates no dependence on others and 54 points indicates complete dependence. In order to facilitate interpretation of this rating system, we standardized the score to fit on a scale of 0 to 100. With this scale, it is possible to stratify a wide variety of patients, ranging from those who require only a few minor modifications in their daily routine (such as changing the type of clothes that they wear in order to facilitate independent dressing) to those who are entirely dependent on others. The average preoperative score was 39 points (range, 25 to 48 points). These scores reflect the substantial dependence of our patients on the help of others for self-care activities, travel, and basic homemaking needs. Our patients had little difficulty with walking or communication.
Disabilities of the Arm, Shoulder, and Hand Questionnaire All seventeen respondents noted severe difficulty with, or an inability to perform, nine selected activities before the index procedure; these included the ability to place an object on a shelf above their head, perform strenuous household chores, perform tasks related to gardening or yard work, carry an object weighing more than ten pounds (4.5 kilograms), change a lightbulb overhead, wash or blow-dry their hair, wash their back, participate in recreational activities requiring some strength, and participate in recreational activities requiring repetitive motion. Twelve of the seventeen respondents noted severe difficulty with, or an inability to perform, seven other activities: opening a new jar or one with a tight lid, preparing a meal, pushing open a heavy door, making a bed, carrying a shopping bag or briefcase, putting on a pullover sweater, and participating in light recreational activities. Eight of the eleven patients who had involvement of the dominant extremity had severe difficulty with, or were incapable of, writing, turning a key, or using a knife to cut food. All seventeen patients had moderate-to-severe pain that was fairly constant, and all had severe or extreme pain with specific activities. Eight patients had severe difficulty sleeping, and four had moderate difficulty. All seventeen patients felt less capable, confident, or useful during the period that the humerus remained ununited. The average preoperative score based on these questionnaires was 77 points (range, 53 to 94 points) on a scale in which 0 points indicates no disability and 100 points indicates extreme disability.
Modified Scale of Constant and Murley7 The patients were asked to demonstrate the ability to bring the hand to the waist, to the xiphoid, to the neck, to the top of the head, and above the head. Forward elevation and lateral elevation, as measured with a goniometer, were given a maximum of 10 points each. Internal rotation and external rotation were also given a maximum of 10 points each, on the basis of the patients' ability to perform composite movements. Rotation is usually combined with forward elevation and abduction to perform activities of daily living. We measured the strength of the involved upper extremity by comparing it with that of the contralateral upper extremity rather than using the method of Moseley34, which involves a spring balance. We placed the shoulder in 90 degrees of abduction (or the maximum abduction possible) and compared the degree of isometric resistance to forced adduction with that of the contralateral extremity. The strength of the involved limb was expressed as a percentage of that of the uninvolved limb, and the point value for strength was determined by dividing the percentage by four. The average preoperative score according to the modified scale of Constant and Murley was 8 points (range, 0 to 27 points) of a possible 100 points.
Radiographic Evaluation
Rating of Results
Statistical Analysis
Twenty of the twenty-two fractures united within six months of the index operation. In two patients, a fracture line was still visible on the radiographs; however, there was no evidence of progressive loosening of the plate or the screws at the time of the most recent follow-up evaluation (two years and seven months for one and three years and four months for the other). One of the two patients was a seventy-six-year-old woman who had had the nonunion for sixteen years before the index procedure. Two attempts at stabilizing the fracture with the use of an intramedullary rod had been unsuccessful. The patient had a loose implant, a four-centimeter-long absolute osseous defect, and nine centimeters of relative bone loss. Fixation with a bridge plate that extended over 90 percent of the length of the humerus and that had been contoured to stand away from the bone at the site of nonunion (so-called wave-plate osteosynthesis), together with an autogenous cancellous bone graft, led to substantial formation of bone. Six months after the procedure, there was radiographic evidence of lucency around some of the screws. At the most recent follow-up evaluation, there were no signs of breakage of the implant but a fracture line was still visible on radiographs. The second patient who had an incomplete union was an eighty-four-year-old woman who had had two previous operations. At the time of the initial evaluation, she had an infection at the site of nonunion in the distal third of the diaphysis; it had been present for two years and three months. Three years and four months after the index procedure, the fixation devices had not loosened or broken but the fracture line remained visible on radiographs. Five patients were followed for a limited duration (average, one year and six months; range, one year to one year and eleven months). Four of the five patients died, at an average of two years and eight months (range, one year and six months to three years and four months) after the procedure. The fifth patient had severe worsening of dementia, was unable to care for herself, and moved to a skilled nursing facility two years and six months after the procedure. In all five patients, the nonunion healed and there was no evidence of loosening of the fixation devices. The average postoperative score according to the modified rating system of Constant and Murley was 69 points (range, 37 to 91 points) for these five patients. The average preoperative score had been 0 points for three of these patients, 4 points for one, and 21 points for one. The discrete rating according to the modified system of Constant and Murley was excellent for two patients, good for two, and poor for one. The poor result was for the patient who had had a resection arthroplasty of the glenohumeral joint after removal of a total shoulder prosthesis because of infection. The remaining seventeen patients were followed for an average of three years and one month (range, two years to five years and ten months). The average score according to the modified rating system of Constant and Murley increased from 9 points (range, 0 to 27 points) preoperatively to 72 points (range, 34 to 95 points) at the time of the most recent follow-up (p < 0.001). The average standardized score according to the Enforced Social Dependency Scale decreased from 39 points (range, 25 to 48 points) preoperatively to 9 points (range, 0 to 36 points) at the time of the most recent follow-up (p < 0.001). The average score with use of the Disabilities of the Arm, Shoulder, and Hand Questionnaire decreased from 77 points (range, 53 to 91 points) preoperatively to 24 points (range, 1 to 78 points) at the time of the most recent follow-up (p < 0.001). (It is necessary to keep in mind the limitations of preoperative scoring with that questionnaire, which relies on retrospective assessment of the preoperative status.) There was a very strong linear correlation between the postoperative scores according to the modified rating system of Constant and Murley and those according to the Disabilities of the Arm, Shoulder, and Hand Questionnaire at the time of the most recent follow-up (r2 = 0.869, p < 0.001). The discrete ratings according to the Disabilities of the Arm, Shoulder, and Hand Questionnaire were excellent for nine of the seventeen patients, good for four, fair for two, and poor for the two who had a persistent nonunion. The discrete ratings according to the modified system of Constant and Murley were excellent for nine of the twenty-two patients, good for eight, fair for three, and poor for two. These discrete ratings reflected the high correlation between the two scales. The average score for the twenty-two patients according to the modified Constant and Murley rating system was 72 points (range, 34 to 95 points) postoperatively compared with 8 points (range, 0 to 27 points) preoperatively. Complications included postoperative delirium, the need for a postoperative blood transfusion, and a stitch abscess in one patient each. Two patients had a fibrous union. There were no deep infections or breakage of the hardware. One patient had transient radial nerve palsy but had complete recovery in six weeks. Another patient fell out of bed six weeks after the index procedure and sustained a minimally displaced spiral fracture of the supracondylar region distal to the plate. The fracture healed after it was treated with a functional brace.
Management of an older patient who has an ununited fracture ot the upper extremity is challenging because of the hazards posed by osteopenic bone and the potential for medical complications due to associated comorbidities. The possible risks and problems of operative intervention in this population may dampen interest in operative treatment. Alternative treatment, such as support of the limb in a functional brace, is often considered19,39-41. It is a viable option for hypertrophic or fibrous nonunions that are relatively stable, but it is less likely to have a satisfactory result when a patient has a painful, unstable, atrophic, or synovial nonunion. The patients in the present series had a painful, unstable, and nearly functionally useless upper extremity. The extremity was typically maintained in a dependent position against the trunk, often in a sling or brace, or both. The disability that ensues from such a position, particularly if the dominant extremity is involved, is considerable. Simple activities of daily living, such as eating, bathing, and dressing, were very difficult for these patients. This difficulty was retrospectively reflected by the relatively high preoperative score according to the Enforced Social Dependency Scale and by the extreme difficulty that patients had performing many functional tasks as documented with the Disabilities of the Arm, Shoulder, and Hand Questionnaire. Elderly patients seem to be less capable of adapting to musculoskeletal disabilities and may become dependent on others for the accomplishment of simple daily activities6,24,44. If it is assumed that obtaining union of these ununited humeri to alleviate the accompanying disability is beneficial, Rosen's question regarding whether fixation is feasible40 must be answered. The challenge of providing stable fixation in the presence of substantial osteopenia is formidable. The osteopenia in our patients not only was the result of advanced age and postmenopausal changes but also reflected the rapid loss of bone associated with disuse after an injury14,16,26,28,48. Factors that contribute to the decrease in bone density in an injured extremity have been postulated to include immobilization, diminished muscle tone, impaired function of the limb, and limitation of weight-bearing. In addition, bone loss is more severe and bone density is less readily recovered in elderly patients16. A direct linear correlation has been demonstrated between the density of bone and the security of screw fixation (r = 0.89 or more)46. A wide array of techniques have been recommended for enhancing plate-and-screw fixation in osteopenic bone4,8,9,13,18,21,25,33,40,43,47, and new techniques continue to evolve10,18,20,29,30. The index procedure was based on basic principles of fixation of osteopenic bone. These principles merit emphasis. First, a long plate should be used. Biomechanical studies have demonstrated that the strength of fixation is enhanced more by the length of the plate, which affects the spacing of the screws, than by the number of screws45. The plate for a mid-diaphyseal fracture should extend nearly the entire length of the bone (from one metaphysis to the other). Extensile exposure of nearly the entire humerus can be accomplished through the direct lateral32, the anterolateral12, or the medial18 approach without substantial risk to muscle or neurovascular structures. Second, a blade-plate is useful for providing secure fixation of the osteopenic, primarily metaphyseal bone of a smaller articular fragment4,9,18,21,25,33,40,43. The broad, fixed-angle blade gains a more predictable hold than standard screws in osteopenic metaphyseal bone. Third, if a standard 4.5-millimeter cortical-bone screw loosens, insertion of a 6.5-millimeter cancellous-bone screw into the track can be attempted. An alternative is to fill the screw-hole with polymethylmethacrylate, with care taken to limit extrusion of the cement, particularly near the fracture site. The screw is then placed into the hole. When the cement is nearly hard, a final one-half turn is applied35,39. Finally, a better alternative may be to anticipate that standard screws will not function adequately and to use Schuhli nuts to transform each screw into a fixed-angle device that will not lose its function if the screw-threads loosen in the bone because of osteopenia20,22,30. The use of these principles, techniques, and implants led to a high rate of union in the patients in the present series. The skeletal fixation was sufficiently secure to prevent progressive loosening or breakage of the implants, even in the two patients who did not have radiographic evidence of union. It is the functional results, however, that are most striking. The disability associated with an ununited fracture of the humeral diaphysis can be substantial and, particularly in an elderly patient, should be a major factor in the decision-making process regarding management. Dramatic functional gains were the rule, and even the patients who had a fair or poor overall result were very satisfied with the outcome of the procedure. Table I, Table II
*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.
  CiteULike  Connotea  Del.icio.us  Facebook  Technorati  Twitter What's this?
This article has been cited by other articles:
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Top
Abstract
Introduction
| home | CME | help | feedback | subscriptions | archive | site index |
|
Stanford University Libraries' HighWire Press (TM) assists in the publication of JBJS Online. |