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Background: The use of coring instrumentation for osteochondral allograft (OCA) transplantation of the femoral trochlea is challenging due to the complex topography of this anatomical area. Purpose: We sought to determine the effect of flat guides versus guides contoured to the surface of the trochlea on graft step-off in trochlear OCAs performed on a foam bone model. We also determined the effect of surgeon experience level and graft size on step-off. Study Design: Controlled laboratory study. Methods: Allograft harvesters were produced in 3 different sequential sizes with either a flat or a contoured undersurface. The guides matched one another in all aspects of shape and size except for the undersurface contour. The contoured undersurface generally matched the surface of the bone model trochlea but was not customized to that surface. A total of 72 foam femora were obtained. Identical trochlear stellate lesions of 3 different sizes (small, medium, and large) were created using 3-dimensional printed surface templates. A total of 6 surgeons (3 attending and 3 resident surgeons) performed OCAs of each trochlear lesion. Each surgeon performed 1 graft for each size and each guide type (n = 6 per surgeon). A specialized digital caliper was prepared that allowed the measurement of graft step-off to within 0.01 mm at a distance of 5 mm between the 2 sensors. The measurements were performed at 8 positions around the clockface of the grafts. Results: Grafts performed with the contoured guides had a mean step-off of 0.43 ± 0.37 mm. Grafts performed with the flat guides had a mean step-off of 0.74 ± 0.78 mm ( P < .0001). Experience level did not have a significant effect on graft step-off ( P = .81). There was no identifiable pattern indicating higher step-off at any one position on the clockface. Conclusion: In this study, contoured grafts had significantly lower step-offs compared with flat guides. Experience level, clockface position, and graft size did not affect step-off.

BackgroundTotal knee arthroplasty (TKA) is an effective treatment method for severe osteoarthritis of the knee. Poor alignment of a knee replacement has been associated with suboptimal clinical results. Traditionally, mechanical alignment (MA) has been considered the gold standard. In light of reports of decreased satisfaction with TKA, a new technique called kinematic alignment (KA) has been developed. The purpose of this study is to (1) review the results of KA and MA for TKA in randomized controlled trials based on the Western Ontario and McMaster Universities Arthritis Index score, the Oxford Knee Score, and the Knee Society Scores, (2) perform a meta-analyses of the randomized controlled trials with baseline and follow-up values of these parameters, and (3) discuss other shortcomings of this literature from the perspective of study design and execution.MethodsTwo independent reviewers performed a systematic review of the English literature using the Embase, Scopus, and PubMed databases searching for randomized controlled trials of MA vs KA in TKA. Of the initial 481 published reports, 6 studies were included in the final review for meta-analysis. The individual studies were then analyzed to evaluate for risks of bias and inconsistencies of methodology.ResultsA majority of studies demonstrated low risk of bias. All studies had fundamental technical issues by utilizing different techniques to achieve KA vs MA. There was no significant difference between KA and MA in these studies.ConclusionsThere is no significant difference in any outcomes measured between KA and MA in TKA. Both statistical and methodological factors diminish the value of these conclusions.

Background The alignment of the lower extremity has important implications in the development of knee arthritis. The effect of incremental rotations of the limb on common parameters of alignment has not been studied. The purpose of the study was to (1) determine the standardized neutral position measurements of alignment and (2) determine the effect of rotation on commonly used measurements of alignment. Methods Eighty-seven full length CT angiography studies (49 males and 38 females, average age 66 years old) were included. Three-dimensional models were created using a rendering software program and placed on a virtual plane. An image of the extremity was obtained. Thirty scans were randomly selected, and those models were rotated in 3° intervals around the longitudinal axis and additional images were obtained. Results In the neutral position, the mechanical lateral distal femoral articular angle (mLDFA) was 85.6 ± 2.3°, medial proximal tibial angle (MPTA) was 86.1 ± 2.8°, and mechanical tibiofemoral angle (mTFA) was −0.7 ± 3.1°. Females had a more valgus alignment with a mTFA of 0.5 ± 2.9° while males had a more varus alignment with a mTFA of −1.7 ± 2.9°. The anatomic tibiofemoral angle (aTFA) was 4.8 ± 2.6°, the anatomic lateral distal femoral angle (aLDFA) measured 80.2 ± 2.2°, and the anatomical-mechanical angle (AMA) was 5.4 ± 0.7°. The prevalence of constitutional varus was 18%. The effect of rotation on the rotated scans led to statistically significant differences relative to the 0° measurement for all measurements. These effects may be small, and their clinical importance is unknown. Conclusions This study provides new information on standardized measures of lower extremity alignment and the relationship between discreet axial rotations of the entire lower extremity and these parameters.

This report describes the arthroscopic management of a case of incarcerating pincer-type femoroacetabular impingement. The hip joint had a marked restriction of range of motion and secondary pain as a result of osteophytes wrapping around the femoral head down the femoral neck. The patient was treated with staged bilateral hip arthroscopy. The procedures were initially performed through the peripheral compartment to remove the incarcerating acetabular rim, followed by arthroscopy of the central compartment with acetabuloplasty and femoral head osteochondroplasty. The patient's treatment has led to an excellent clinical and radiographic result at 24 months' follow-up despite an unrelated pelvic fracture sustained in the postoperative period. This technique emphasizes the capabilities of hip arthroscopy in advanced cases of femoroacetabular impingement as an alternative to arthroplasty for patients with healthy articular cartilage.

Background: It is unclear whether simultaneous-bilateral total knee arthroplasty is as safe as staged-bilateral arthroplasty is. We are aware of no randomized trials comparing the safety of these surgical strategies. The purpose of this study was to retrospectively compare these two strategies, with use of an intention-to-treat approach for the staged-bilateral arthroplasty cohort. Methods: We used linked hospital discharge data to compare the safety of simultaneous-bilateral and staged-bilateral knee arthroplasty procedures performed in California between 1997 and 2007. Estimates were generated to take into account patients who had planned to undergo staged-bilateral arthroplasty but never underwent the second procedure because of death, a major complication, or elective withdrawal. Hierarchical logistic regression modeling was used to adjust the comparisons for patient and hospital characteristics. The principal outcomes of interest were death, a major complication involving the cardiovascular system, and a periprosthetic knee infection or mechanical malfunction requiring revision surgery. Results: Records were available for 11,445 simultaneous-bilateral arthroplasty procedures and 23,715 staged-bilateral procedures. On the basis of an intermediate estimate of the number of complications that occurred after the first procedure in a staged-bilateral arthroplasty, patients who underwent simultaneous-bilateral arthroplasty had a significantly higher adjusted odds ratio (OR) of myocardial infarction (OR = 1.6, 95% confidence interval [CI] = 1.2 to 2.2) and of pulmonary embolism (OR = 1.4, 95% CI = 1.1 to 1.8), similar odds of death (OR = 1.3, 95% CI = 0.9 to 1.9) and of ischemic stroke (OR = 1.0, 95% CI = 0.6 to 1.6), and significantly lower odds of major joint infection (OR = 0.6, 95% CI = 0.5 to 0.7) and of major mechanical malfunction (OR = 0.7, 95% CI = 0.6 to 0.9) compared with patients who planned to undergo staged-bilateral arthroplasty. The unadjusted thirty-day incidence of death or a coronary event was 3.2 events per thousand patients higher after simultaneous-bilateral arthroplasty than after staged-bilateral arthroplasty, but the one-year incidence of major joint infection or major mechanical malfunction was 10.5 events per thousand lower after simultaneous-bilateral arthroplasty. Conclusions: Simultaneous-bilateral total knee arthroplasty was associated with a clinically important reduction in the incidence of periprosthetic joint infection and malfunction within one year after arthroplasty, but it was associated with a moderately higher risk of an adverse cardiovascular outcome within thirty days. If patients who are at higher risk for cardiovascular complications can be identified, simultaneous-bilateral knee arthroplasty may be the preferred surgical strategy for the remaining lower-risk patients. Level of Evidence: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Several studies support the concept that, for optimum range of motion in THA, the combined femoral and acetabular anteversion should be some constant or fall within some “safe zone.” When using a cementless femoral component, the surgeon has little control of the anteversion of the component since it is dictated by native femoral anteversion. Given this constraint, we asked whether the surgeon should use the native anteversion of the acetabulum as a target for implant position in THA. Forty-six patients scheduled for primary THA underwent CT scanning and preoperative planning using a computer workstation. The native acetabular anteversion and the native femoral anteversion were measured. Prosthetic femoral anteversion was measured on the workstation by three-dimensional templating of a straight-stemmed tapered implant. The mean of the sum of the native acetabular anteversion and native femoral anteversion was 28.9°; however, 17% varied by 10° to 15° and 11% by more than 15°. The mean of native femoral anteversion and prosthetic femoral anteversion was 13.8° (range, −6.1°–32.7°) and 22.5° (range, 1°–39°), respectively. Based on our data, we believe the surgeon should not use the native acetabular anteversion as a target for positioning the acetabular component.

We present 2 cases of cam/pincer combined femoroacetabular impingement treated arthroscopically with labral debridement, acetabuloplasty, and femoral head recontouring. In both cases there was essentially no evidence of osteoarthritis of the hip. However, in both cases raised exostoses were evident on the anterolateral femoral neck in the region that commonly comes into contact with the acetabular rim. On the basis of 3-dimensional dynamic reconstructions, we surmise that these exostoses are a direct result of linear contact between the femoral neck and acetabular rim. We recommend that the presence of these exostoses be carefully noted by the arthroscopic hip surgeon and that they be a geographic marker of the zone of contact between the head-neck junction and the acetabular rim and a guide for the area of head osteochondroplasty in combination with appropriate treatment of the acetabular rim.

Analysis of deformity and subsequent correction are the basis for many orthopaedic surgical procedures. In advanced cases of joint degeneration, arthroplasty may be the only available treatment option. Until recently, these analyses and preoperative surgical plans have been performed using standard radiographs, tracing paper, and/or plastic overlays. Numerous customized, commercially available, computer-based preoperative planning software programs have been introduced. The purposes of this study were to describe (1) the techniques used in deformity analysis and preoperative surgical planning using standard radiographs for joint arthroplasty and corrective osteotomies of the extremities, (2) the use of computed tomography (CT) scans to analyze rotational deformities in the presence and absence of joint prostheses and in planning corrective rotational osteotomies or revision joint replacement, and (3) the techniques for analyzing angular deformities of the spine. All these applications were performed with a widely available image analysis software.

Periprosthetic fractures involving a total knee arthroplasty pose a challenging treatment problem with a prevalence of up to 2.5% in the literature (Instr Course Lect 2001;50:379-389). The supracondylar region of the femur is commonly involved, often with minimal available bone in contact with the components. The clinical challenges are particularly more complex in the case of a combined distal femoral and proximal tibial periprosthetic fracture. This injury is considered a "floating prosthesis" injury because of the complete separation of the prosthesis from the remaining skeleton. In this report, a floating prosthesis injury, in combination with a femoral shaft fracture, is treated with 2 locking plates using a minimally invasive technique, with limited blood loss, immediate pain relief after surgery, and successful healing of all fractures with minimal deformity.

BackgroundThe treatment of osteochondritis dissecans in the adult knee can be challenging. As part of our comprehensive treatment program, fresh osteochondral allografts have been used in the surgical management of osteochondritis dissecans of the femoral condyle.HypothesisFresh osteochondral allograft transplantation will provide a successful surgical treatment for osteochondritis dissecans of the femoral condyle.Study DesignCase series; Level of evidence, 4.MethodsSixty-six knees in 64 patients underwent fresh osteochondral allografting for the treatment of osteochondritis dissecans. Each patient was evaluated both preoperatively and postoperatively using an 18-point modified D'Aubigné and Postel scale. Subjective assessment was performed using a patient questionnaire. Radiographs were evaluated preoperatively and postoperatively.ResultsMean follow-up was 7.7 years (range, 2-22 years). There were 45 men and 19 women with a mean age of 28.6 years (range, 15-54 years). All patients had undergone previous surgery. Forty-one lesions involved the medial femoral condyle, and 25 involved the lateral femoral condyle. All were osteochondritis dissecans type 3 or 4. The mean allograft size was 7.5 cm2. One knee was lost to follow-up. Of the remaining 65 knees, 47 (72%) were rated good/excellent, 7 (11%) were rated fair, and 1 (2%) was rated poor. Ten patients (15%) underwent reoperation. The mean clinical score improved from 13.0 preoperatively to 16.4 postoperatively (P < .01). Fifty-nine of 64 patients completed questionnaires. Subjective knee function improved from a mean of 3.4 to 8.4 on a 10-point scale (P < .01).ConclusionWith greater than 70% good or excellent results, fresh osteochondral allograft transplantation is a successful surgical treatment for osteochondritis dissecans of the femoral condyle.

Acetabular retroversion has been proposed to contribute to the development of osteoarthritis of the hip. For the diagnosis of this condition, conventional AP pelvic radiographs may represent a reliable, easily available diagnostic modality as they can be obtained with a reproducible technique allowing the anterior and posterior acetabular rims to be visible for assessment. This study was designed to: (i) determine cranial, central, and caudal anatomic acetabular version (AV) from cadaveric specimens; (ii) establish the validity and reliability of the radiographic measurements of central acetabular anteversion; and (iii) determine the validity and reliability of the radiographic "cross-over-sign" to detect acetabular retroversion. Using 43 desiccated pelvises (86 acetabuli) the anatomic AVs were measured at three different transverse planes (cranially, centrally, and caudally). From these pelvises, standardized AP pelvic radiographs were obtained. To directly measure central AV, a modified radiographic method is introduced for the use of AP pelvic radiographs. The validity and reliability of this radiographic method and of the radiographic cross-over-sign to detect cranial acetabular retroversion were determined. The mean central and caudal anatomic AVs were approximately 20 degrees , and the mean cranial AV was 8 degrees . Cranial retroversion (AV < 0 degrees ) was present in 19 of 86 hips (22%). A linear correlation was found between the central and cranial AV. Below 10 degrees of central AV, all acetabuli were cranially retroverted. Between 10 degrees and 20 degrees , 30% of the acetabuli were cranially retroverted, and above 20 degrees , only 1 of 45 acetabuli was cranially retroverted. The radiographic measurement of the central AV (20.3 +/- 6.5 degrees ) correlated strongly with the anatomic AV (20.1 +/- 6.4 degrees ). The sensitivity of the cross-over-sign to detect a cranial acetabular anteversion of less than 4 degrees was 96%, its specificity 95%, and the positive predictive and negative predictive values 90% and 98%, respectively. Both the modified radiographic anteversion measurements and the cross-over-sign demonstrated substantial inter- and intraobserver reliability. Retroversion is almost exclusively a problem of the cranial acetabulum. The cranial AV is on average 12 degrees lower than the central AV, with the latter directly measurable from AP pelvic radiographs. A central AV of less than 10 degrees was associated with cranial retroversion. The presence of a positive cross-over-sign is a highly reliable indicator of cranial AV of

Fresh osteochondral allografting is a nonvascularized organ transplantation with a clinical use dating back to the early twentieth century. The procedure, in its current form, involves transplantation of a small segment of bone as a carrier with its overlying cartilage. As the bone is remodeled and revascularized by the recipient, the donor cartilage continues to function mechanically, produces matrix, and receives nutrition from the synovial fluid. The cartilage has traditionally been considered a so-called immunoprivileged tissue, avoiding the immune surveillance of the host presumably because of its paucity of vascular channels and its hypo-cellular matrix1. These qualities make fresh osteochondral allografting unique in the field of transplantation and preclude the need for systemic immunosuppression after this procedure. Although histologically normal articular cartilage has been reported in retrieved fresh osteochondral allografts, we know of no report that has definitively confirmed the specific survival of the donor cells for any length of time. Furthermore, the source of cells in retrieved transplants has not been confirmed as being from the donor or the recipient. The patient was informed that data concerning his case would be submitted for publication. Atwenty-two-year-old man with a large defect on the articular surface of the lateral femoral condyle of the knee underwent fresh osteochondral allografting from a female donor. He recovered well from the allograft procedure and had a relatively pain-free knee for the next twenty-five years. He presented to us with knee pain on the lateral side and tricompartmental arthritis predominantly in the lateral compartment (Fig. 1). A magnetic resonance imaging scan was acquired, and it demonstrated a tear of the posterior horn of the lateral meniscus with loss of the articular cartilage thickness along the posterior aspect of the lateral femoral condyle (Fig. 2). He ultimately requested total knee …

The search for improved femoral fixation in cemented total hip arthroplasty is ongoing. Two design variables, surface finish and stem contour, were evaluated. Sixteen titanium femoral stems of one design were cemented into fiberglass femora. One half of the components had a polished surface and the rest had a roughened finish. Within each group, 4 stems had vertically oriented ribs on the proximal portion and 4 did not. Micromotion was measured in a stair climbing simulator with loading to a joint reaction force of 200 kg for 6 million cycles. Micromotion increased throughout the course of the experiment. Stems with a polished surface had significantly higher micromotion. Although stems with ribs had less micromotion compared with those without ribs, this difference was not statistically significant.

Twenty knees in 18 patients were treated (mean age, 42 years; range, 19-64 years) with fresh osteochondral allografting limited to the patellofemoral joint. The knees were analyzed retrospectively to determine the rate of successful outcomes. The trochlea and patella were treated in 12 patients and

Background: Isolated revision of an acetabular total hip component is associated with special problems related to the retention of the femoral component. We reviewed the intermediate-term results of a series of such operations with use of the Harris-Galante Porous acetabular component. Methods: We retrospectively studied the results of ninety-five isolated acetabular revisions, specifically focusing on sixty-three that had been followed for a minimum of sixty months (average, 130 months). Evaluation measures included the Harris hip score, radiographic analysis, complications, and prosthetic survival. Follow-up information was obtained with self-administered questionnaires, telephone contact, and/or clinical examination. The effects of a femoral component with a modular neck-head junction and of trochanteric osteotomy on the dislocation rate were evaluated. Results: Nine shells were rerevised: four because of recurrent dislocation, four because of aseptic loosening, and one because of dissociation of the liner. The survival rate with rerevision of the shell as the end point was 90.5% at 120 months. Pelvic osteolysis occurred in 4% of the cases. The dislocation rate for the sixty-three hips was 8%. When femoral component modularity was accounted for, the analysis of the dislocations revealed a significantly higher dislocation rate for the hips without a trochanteric osteotomy (p = 0.04). Eight arthroplasties were complicated by nerve palsies, seven of which resolved fully or nearly so. Conclusions: Isolated acetabular revision with use of the Harris-Galante Porous acetabular component was associated with a low rate of loosening, lysis, and rerevision of the shell at the time of intermediate-term follow-up. However, there was a high rate of complications, including trochanteric nonunion, dislocation, and nerve palsy. The performance of a trochanteric osteotomy was associated with a decreased rate of dislocation. Level of Evidence: Therapeutic study, Level IV (case series [no, or historical, control group]). See Instructions to Authors for a complete description of levels of evidence.

Tenotomy is a commonly encountered event in orthopaedic surgery. In 23 rabbit extensor digitorum longus (EDL) muscles, within 24 h after tenotomy, a marked drop in maximum force production occurred. This was not explainable based on architectural changes and histological examination using standard markers for muscle injury, i.e., haematoxylin and eosin morphology, developmental myosin heavy chain (MHC) immunolabeling, and quantitation of muscle fiber type percentage, area and distribution. The expression of neural cell adhesion molecule (NCAM), a glycoprotein expressed during muscle development was measured as a function of time in these muscles. NCAM expression was increased as early as one day after tenotomy with 2:2 � 1:2% of the fibers showing positive expression. This expression level increased significantly to 15:4 � 15:2% after 7 days and then subsided to 13:2 � 10:6% 21 days after tenotomy. Two-way analysis of variance demonstrated a significant effect of time and a significant time x tenotomy method interaction. These results suggest that tenotomy leads to possible changes in muscle–nerve connections and/or excitation–contraction (EC) coupling. 2002 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.

Educational Objectives As a result of reading this article, physicians should be able to: 1. Identify the etiology of femoroacetabular impingement. 2. Assess femoroacetabular impingement on physical examination. 3. Recognize femoroacetabular impingement on imaging studies. 4. Discuss modern techniques to effectively treat femoroacetabular impingement, both open and arthroscopic. Femoroacetabular impingement (FAI) is a recently proposed concept describing abnormal anatomic relationships within the hip joint that may lead to articular damage. Impingement is caused by bony deformities or spatial malorientation of the femoral head-neck junction and/or the acetabulum. These abnormalities lead to pathologic contact and shearing forces at the acetabular labrum and cartilage during physiological hip motion. There is an increasing body of evidence that these forces lead to cartilage wear and eventual osteoarthritis. Treatment options for FAI are evolving rapidly. Although the gold standard remains open hip dislocation, arthroscopic techniques have shown significant promise. It is possible that early recognition and treatment of subtle deformity about the hip may reduce the rate of hip osteoarthritis in the future. [ Orthopedics. 2015; 38(3):185–199.]

Cam morphology in femoroacetabular impingement has been implicated in the development of osteoarthritis. The alpha angle and femoral head/neck offset are widely used to determine femoral head asphericity. To our knowledge, no study has evaluated the alpha angle circumferentially using three-dimensional imaging in a population of healthy individuals of adolescent age.We sought to (1) determine normal values for the alpha angle in adolescents, (2) define the location along the neck with the highest alpha angle, and (3) determine normal femoral head and neck radii and femoral head/neck offset.Fifty CT scans from a database of scans obtained for reasons not related to hip pain were studied. The average age of the subjects was 15 years (range, 14-16 years). Alpha angle and femoral head/neck offset were measured circumferentially.The alpha angle averaged 40.66 ± 4.46 mm for males and 37.77 ± 5.65 mm for females. The alpha angle generally was highest between the 11:40 and 12:40 o'clock and between the 6:00 and 7:40 o'clock positions. The femoral head radius was 24.53 ± 1.74 mm for males and 21.94 ± 1.13 mm for females, and the femoral neck radius was 16.14 ± 2.32 mm for males and 13.82 ± 2.38 mm for females. The mean femoral head/neck offset was 8.39 ± 1.97 mm for males and 8.13 ± 2.27 mm for females.In this healthy population of 14- to 16-year-old subjects, the highest alpha angle was at the superior and inferior aspects of the heads rather than at the anterosuperior aspect. This information will provide benchmark values for distinction between normal and abnormal morphologic features of the femoral head.

Fresh osteochondral allografts have been widely used to treat cartilage lesions for more than 100 years1. Transplantation of cartilage and bone in the form of an allograft allows osseous healing while maintaining the articular cartilage architecture. This composite tissue transplant remains intact in vivo for extensive periods of time with a favorable mechanical and biological environment. The chondrocytes of the graft are thought to actively remodel the extracellular matrix environment, and thus contribute to the tissue integrity. We recently reported that allograft cells could survive up to twenty-nine years after transplantation without the need for systemic immunosuppression2. Although mosaic cell populations have been demonstrated in other forms of transplantation, these have always been under the umbrella of long-term systemic immunosuppression3,4. In a classic study, Langer and Gross5 showed that intact articular cartilage surfaces obtained by removing the subchondral bone of rat femoral heads and filling of the osseous segments with acrylic cement exhibited essentially no humoral immune response in contrast to that seen with minced cartilage or isolated chondrocyte transplants. This finding has been attributed to the so-called “immunoprivileged” status of articular cartilage, which protects the chondrocytes from the immune system of the host. The extent to which allograft chondrocytes retain their gene expression profiles and chondrogenic capacities remains unknown. Our goal was to compare gene expression, proliferation rate, and chondrogenic potential between host and allograft chondrocytes isolated three years after an unsuccessful fresh osteochondral allograft transplant in the knee. The patient was informed that data concerning her case would be submitted for publication, and she provided consent. The study was performed in full compliance with our institutional review board (IRB). Our IRB at University of California Davis Medical Center does not consider case reports to be research and does not …

A low-contact stress, high-congruity, mobile-bearing patellofemoral joint arthroplasty decreases the contact force in the patellofemoral joint, theoretically reducing patellar polyethylene wear and increasing implant longevity. This article describes the case of a 47-year-old obese woman who presented with pain and loss of extension after a low-contact stress, high-congruity, mobile-bearing patellofemoral joint arthroplasty. Radiographs revealed dislocation (ie, spinout) of the patellar polyethylene. Patellar polyethylene spinout is a rare complication of metal-backed, mobile-bearing patellar resurfacing. Theoretically, patellar polyethylene spinout in low-contact stress, high-congruity, mobile-bearing patellofemoral arthroplasty is related to implant design and the placement of the metal base plate. Ultimately, the articulation of low-contact stress, high-congruity, mobile-bearing patellofemoral arthroplasty may be too congruent to resist the forces of the patellofemoral joint, particularly in patients who are obese, and the patellar rotation allowed by this articulation may not be sufficient for all patients. Should patellar spinout occur, replacement of the polyethylene is not sufficient to correct the problem; hence, revision of the patellar and trochlear components is required because it remains unclear whether failure is secondary to patellar or trochlear design deficiencies.

Background: This study was proposed to investigate the changes in the utilization of knee arthroscopy in an ambulatory setting over the past decade in the United States as well as its implications. Methods: The National Survey of Ambulatory Surgery, last carried out in 1996, was conducted again in 2006 by the Centers for Disease Control and Prevention. We analyzed the cases with procedure coding indicative of knee arthroscopy or anterior cruciate ligament reconstruction. To produce estimates for all arthroscopic procedures on the knee in an ambulatory setting in the United States for each year, we performed a design-based statistical analysis. Results: The number of arthroscopic procedures on the knee increased 49% between 1996 and 2006. While the number of arthroscopic procedures for knee injury had dramatically increased, arthroscopic procedures for knee osteoarthritis had decreased. In 1996, knee arthroscopies performed in freestanding ambulatory surgery centers comprised only 15% of all orthopaedic procedures, but the proportion increased to 51% in 2006. There was a large increase in knee arthroscopy among middle-aged patients regardless of sex. In 2006, >99% of arthroscopic procedures on the knee were in an outpatient setting. Approximately 984,607 arthroscopic procedures on the knee (95% confidence interval, 895,999 to 1,073,215) were performed in an outpatient setting in 2006. Among those, 127,446 procedures (95% confidence interval, 95,124 to 159,768) were for anterior cruciate ligament reconstruction. Nearly 500,000 arthroscopic procedures were performed for medial or lateral meniscal tears. Conclusions: This study revealed that the knee arthroscopy rate in the United States was more than twofold higher than in England or Ontario, Canada, in 2006. Our study found that nearly half of the knee arthroscopic procedures were performed for meniscal tears. Meniscal damage, detected by magnetic resonance imaging, is commonly assumed to be the source of pain and symptoms. Further study is imperative to better define the symptoms, physical findings, and radiographic findings that are predictive of successful arthroscopic treatment. Level of Evidence: Prognostic Level II. See Instructions to Authors for a complete description of levels of evidence.

A 39-year-old man presented with weakness and a nonmobile mass in the buttock of 5 months’ duration. Hip flexion was limited to 70°. Strength was diminished for both ankle/foot plantar and dorsiflexion. Sensation was decreased on the plantar and dorsal foot. A pedunculated osseous mass measuring 6×4 cm on the posterior femoral neck was seen on plain radiographs and magnetic resonance imaging. Electromyography showed moderate sciatic neuropathy of the peroneal and tibial branches. The patient underwent excision of the tumor through a posterior approach. Due to the risk of weakening the neck, two 7.3-mm cannulated screws were passed percutaneously into the head with fluoroscopic guidance. The final pathological report indicated the tumor was an osteochondroma. At 22-month follow-up, he had full resolution of the neurologic findings. Postoperatively, the patient reported improvement in numbness and tingling in the leg but continued to have moderate buttock pain. Left hip flexion increased to 115° at last follow-up. The importance of protecting the medial femoral circumflex artery during approaches to the hip is paramount. In this case, the tumor arose from the central aspect of the quadratus femoris, with the superior muscle protecting the medial femoral circumflex artery from harm. Although osteochondromas are a rare cause of mass effect, they should be considered in the differential diagnosis of sciatic nerve compression in this anatomical location.

This study is a retrospective evaluation of the intermediate-term results of 26 consecutive revision total hip arthroplasties performed with a modular titanium, uncemented femoral component. The average patient age at the time of revision total hip arthroplasty was 72 years, and there were an equal number of males and females. The mean follow-up was 5.7 years (ranging from 4 to 11 years). No re-revision was necessary during this follow-up time. The mean Harris hip score improved significantly (preoperative and postoperative score was 50.7 and 89.6, respectively; P < .001). Postoperatively, Short Form 36 functional scores averaged 67.7 across 9 functional parameters. Our observed low revision rate and favorable patient-reported outcome scores support the continuous use of modular titanium, uncemented femoral components in revision total hip arthroplasty.

In the setting of extraarticular deformities of the knee, total knee arthroplasty (TKA) is difficult, as anatomical abnormalities obstruct identification of alignment landmarks and may preclude the use of traditional instrumentation. The long-term clinical value of computer assistance for TKA is a point of ongoing controversy. Few reports describe the use of computer-assisted orthopedic surgery as a method to decrease alignment outliers in TKA with associated posttraumatic deformities. In this report, a 70-year-old woman who had a severe distal femoral deformity from a previous open fracture underwent computer-assisted TKA for osteoarthritis. The use of a computer-assisted navigation system achieved a high degree of accuracy relative to the desired target alignment and led to improved function in a patient in which standard instrumentation was not feasible.

Background Numerous structural deformities of the acetabulum are associated with hip osteoarthritis (OA). Acetabular retroversion has been implicated in the development of femoroacetabular impingement. However, it is unknown if retroversion occurs from isolated excessive bone in the superior acetabulum or a torsional phenomenon of the entire pelvic segment. Questions/purposes A method was developed to measure acetabular version (AV) using 3-D models thus eliminating positional factors. This method was used to determine if acetabular retroversion is an isolated entity or an effect involving the entire pelvic segment containing the acetabulum. Method Fifty pelvic CT scans were selected from a large database. Measurements were performed for abduction, ischial spine position, and AV at multiple levels. The relationships between anteversion at multiple levels and between midacetabular anteversion and ischial spine position were analyzed. Results The mean upper and midlevel acetabular anteversion values were 14.4° ± 10.5° and 21.3° ± 5.8°, respectively. The mean abduction was 39.7° ± 4.3°. The prevalence of acetabular retroversion was 7%. Females had greater anteversion than males at all levels. Correlations were found between Levels 1 and 4 version (r = 0.74) and the ischial spine index and Level 4 version (r = 0.67). Conclusions These data suggest retroversion involves the acetabulum at all levels and includes the entire pelvic segment containing the acetabulum and the ischial spine. Clinical Relevance These data are relevant for surgeons in providing targets for normal positioning of the acetabulum during periacetabular osteotomies and acetabular recontouring procedures.

Prophylactic parenteral antibiotics have contributed to the present low rate of surgical site infections following hip and knee arthroplasty. Over the past decade, there has been a change in the pattern of methicillin-resistant Staphylococcus aureus infections from hospital-acquired to community-acquired. The findings of recent studies on screening programs to identify carriers of methicillin-resistant Staphylococcus aureus have been equivocal, with some studies showing that such programs reduce the rate of infections and others showing no effect on infection rates. Hospitals with antibiogram data that reveal high Staphylococcus resistance should consider use of vancomycin as a prophylactic antibiotic.

Femoroacetabular impingement (FAI) has been recently established as a risk factor in the development of osteoarthritis of the hip. Intraosseous cysts are commonly seen on imaging of FAI. In most cases these cysts are incidental and do not require specific treatment at the time of surgical treatment of hip impingement. However, in some cases the cysts may mechanically compromise the acetabular rim or femoral neck. We present a technique for treating such cysts with an all-arthroscopic technique using a commercially available bone graft substitute composed of cancellous bone and demineralized bone matrix placed within an arthroscopic cannula for direct delivery into the cysts. This technique may be of benefit to surgeons treating FAI with an all-arthroscopic technique.

Posttraumatic osteoarthritis of the knee can be associated with angular deformities and alterations in the joint line as a result of the initial trauma and subsequent surgical procedures. These deformities can be characterized as extra-articular or intra-articular or can involve aspects of both. Conversion to total knee arthroplasty (TKA) may require either a staged or a simultaneous corrective osteotomy to restore the limb alignment and proper knee function. This article describes a closing wedge retrotubercular tibia osteotomy performed concurrently with TKA in an effort to correct an extra-articular varus deformity and to improve the patella tendon height in relation to the reconstructed joint line. A 57-year-old man previously treated for a Schatzker type 6 tibia plateau fracture presented with symptoms of arthritis pain and instability as a result of a varus thrust with weight bearing. Radiographs revealed posttraumatic osteoarthritis, a 35 degrees varus deformity, and patella infera. Maintaining the tibia tubercle continuity with the distal tibia allowed for correction of the varus deformity and improvement in the patella tendon height relative to the joint line. At 5-year follow-up, the patient had osteotomy healing, clinically neutral limb alignment, and improvement in joint line biomechanics with resolution of symptoms of pain and instability.

The accuracy and precision of any computer-aided surgical device is critical to its utility. We asked the following question: how accurate and precise are the values measured by an imageless computer navigation system as compared with those measured using postoperative CT scans? Twenty-five patients (26 hips) underwent primary THA using an imageless computer navigation system for placement of the acetabular component. Inclination and anteversion were measured in the operative coordinate system as defined by Murray. Accuracy, precision, and bias were computed, and Bland-Altman analysis was used to assess levels of agreement. The accuracy (mean +/- standard deviation of the absolute difference between computer-assisted navigation and CT) was 1.8 degrees +/- 1.2 degrees for inclination and 2.0 degrees +/- 2.0 degrees for anteversion. Precision was 3.4 degrees for inclination and 5.5 degrees for anteversion. Bias was 0.52 degrees for inclination and 0.35 degrees for anteversion. Limits of agreement were 4.26 degrees for inclination and 5.58 degrees for anteversion. An imageless computer navigation system can precisely determine acetabular cup position.

Animal models of osteomyelitis traditionally have been characterized by inherent weaknesses related to animal size, differences in clinical findings compared with humans, aggressive behavior, high complication rate, and high cost. In this experiment, a model of tibial osteomyelitis was established in 28 goats with a very low complication rate and a consistent clinical, radiographic, and histologic disease course. The infecting Staphylococcus aureus organism was isolated in all but five of 28 animals (82%), in which there was no growth of bacteria at 24 and 72 hours. All five of these specimens had histologic evidence of osteomyelitis. Twenty-seven of the 28 animals (96%) had radiographic and histologic evidence of osteomyelitis. Clinical progression of the disease was observed by draining wounds, a postoperative limp that subsided in all goats, and varied periods of anorexia despite an average increase in body weight. There were no complications or mortalities related to the establishment of the animal model. This large animal model will provide a practical method of studying osteomyelitis and comparing treatment protocols.

We report on tibiotalar osteochondral shell allografts for post-traumatic ankle arthropathy in seven patients. Average follow-up was 148 months (range, 85 to 198). Patients were evaluated by a questionnaire, SF-12 survey, ankle score, physical exam and radiographs. The ankle score increased from 25 preoperatively to 43 at latest follow-up (maximum score 100). SF-12 scores increased from 30 to 38 (Physical Component) and 46 to 53 (Mental Component). The failure rate was 42%. Four of seven patients reported good or excellent results. Five patients stated they would undergo a similar procedure again. Complications included graft fragmentation, poor graft fit, graft subluxation, and non-union. Follow-up radiographs demonstrated joint space narrowing, osteophytes, and sclerosis, even in cases with excellent clinical status. Fresh osteochondral shell allografting may provide a viable alternative for the treatment of post-traumatic ankle arthrosis in selected individuals.

Arthroscopically assisted reconstruction of the anterior cruciate ligament (ACL) is a common and effective method for treatment of anterior knee instability following ACL injury. Annually, an estimated 250,000 ACL injuries are diagnosed and approximately 100,000 ACL reconstructions are performed in the United States1-3. Chondrolysis is an extremely rare but devastating complication following ACL reconstruction. It is characterized by complete destruction of the articular cartilage and a profound inflammatory response consisting of pain, swelling, and loss of joint motion. The differential diagnosis includes osteonecrosis, direct trauma related to the injury or to the surgical procedure, infection, an adverse reaction to pharmacological agents (including local anesthetic infusions), and unknown causes. Infection after arthroscopic ACL reconstruction is rare: its incidence has been reported as 0.14% to 1.7%2,4-7. The most common causative organisms are Staphylococcus aureus, Staphylococcus epidermidis, and Staphylococcus haemolyticus 2,4-6. When tissue allografts have been used for ACL reconstruction, other organisms such as Peptostreptococcus, Klebsiella, Enterobacter, and Clostridium species as well as gram-negative bacilli have been implicated6,8. Although infrequent, infection can be a devastating complication that leads to septic arthritis, chondrolysis, osteomyelitis, osteochondral destruction, and, in rare cases, death2,5,8,9. We describe a case of medial tibial plateau osteochondral destruction secondary to an Aspergillus flavus fungal infection in an immunocompetent thirteen-year-old girl who had undergone elective ACL reconstruction. The patient and her parents were informed that data concerning the case would be submitted for publication, and they provided their consent. To the best of our knowledge, a case of Aspergillus fungal arthritis following ACL reconstruction has not been previously reported. Furthermore, salvage options outlined in the literature have been limited to primary arthrodesis, prosthetic reconstruction, use …