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Background Demand for total hip arthroplasty (THA) is high and expected to continue to grow during the next decade. Although much of this growth includes working-aged patients, cost-effectiveness studies on THA have not fully incorporated the productivity effects from surgery. Questions/Purposes We asked: (1) What is the expected effect of THA on patients’ employment and earnings? (2) How does accounting for these effects influence the cost-effectiveness of THA relative to nonsurgical treatment? Methods Taking a societal perspective, we used a Markov model to assess the overall cost-effectiveness of THA compared with nonsurgical treatment. We estimated direct medical costs using Medicare claims data and indirect costs (employment status and worker earnings) using regression models and nonparametric simulations. For direct costs, we estimated average spending 1 year before and after surgery. Spending estimates included physician and related services, hospital inpatient and outpatient care, and postacute care. For indirect costs, we estimated the relationship between functional status and productivity, using data from the National Health Interview Survey and regression analysis. Using regression coefficients and patient survey data, we ran a nonparametric simulation to estimate productivity (probability of working multiplied by earnings if working minus the value of missed work days) before and after THA. We used the Australian Orthopaedic Association National Joint Replacement Registry to obtain revision rates because it contained osteoarthritis-specific THA revision rates by age and gender, which were unavailable in other registry reports. Other model assumptions were extracted from a previously published cost-effectiveness analysis that included a comprehensive literature review. We incorporated all parameter estimates into Markov models to assess THA effects on quality-adjusted life years and lifetime costs. We conducted threshold and sensitivity analyses on direct costs, indirect costs, and revision rates to assess the robustness of our Markov model results. Results Compared with nonsurgical treatments, THA increased average annual productivity of patients by USD 9503 (95% CI, USD 1446–USD 17,812). We found that THA increases average lifetime direct costs by USD 30,365, which were offset by USD 63,314 in lifetime savings from increased productivity. With net societal savings of USD 32,948 per patient, total lifetime societal savings were estimated at almost USD 10 billion from more than 300,000 THAs performed in the United States each year. Conclusions Using a Markov model approach, we show that THA produces societal benefits that can offset the costs of THA. When comparing THA with other nonsurgical treatments, policymakers should consider the long-term benefits associated with increased productivity from surgery. Level of Evidence Level III, economic and decision analysis. Electronic supplementary material The online version of this article (doi:10.1007/s11999-016-5084-9) contains supplementary material, which is available to authorized users.

Background: The advent of adverse local tissue reactions seen in metal-on-metal bearings, and the recent recognition of trunnionosis, have led many surgeons to recommend ceramic-on-polyethylene articulations for primary total hip arthroplasty. However, to our knowledge, there has been little research that has considered whether the increased cost of ceramic provides enough benefit over cobalt-chromium to justify its use. The primary purpose of this study was to compare the cost-effectiveness of ceramic-on-polyethylene implants and metal-on-polyethylene implants in patients undergoing total hip arthroplasty. Methods: Markov decision modeling was used to determine the ceramic-on-polyethylene implant revision rate necessary to be cost-effective compared with the revision rate of metal-on-polyethylene implants across a range of patient ages and implant costs. A different set of Markov models was used to estimate the national cost burden of choosing ceramic-on-polyethylene implants over metal-on-polyethylene implants for primary total hip arthroplasties. The Premier Research Database was used to identify 20,398 patients who in 2012 were ≥45 years of age and underwent a total hip arthroplasty with either a ceramic-on-polyethylene implant or a metal-on-polyethylene implant. Results: The cost-effectiveness of ceramic heads is highly dependent on the cost differential between ceramic and metal femoral heads and the age of the patient. At a cost differential of $325, ceramic-on-polyethylene bearings are cost-effective for patients

To encourage the shift to value-based health care, the Center for MedicareMedicaid Innovation created bundled payment programs in which episodes of care are paid for in a bundled fashion. Hip arthroplasty and knee arthroplasty were believed to be good procedures to pilot in bundled payment programs because these procedures had an easily defined episode of care and accounted for a considerable amount of the Medicare budget. Cost savings for hip and knee arthroplasty in bundled payment programs can be divided into cost savings achieved in the operating room, in the hospital, and in the postacute care period. Orthopaedic surgeons should be aware of the clinical results of hip and knee arthroplasty in bundled payment programs in various practice settings, including large healthcare systems, large academic centers, and private practices. Cost savings have been achieved in all phases of hip and knee arthroplasty in bundled payment programs. Almost all successful practice settings have developed an infrastructure to organize, administer, and manage patients through the different phases of patient care in bundled payment programs. Patient-reported outcomes and quality measures are being developed to determine the quality of the services provided in bundled payment programs.

Background Posterior-stabilized total knee arthroplasty (TKA) with gradually variable radii (G-curve) femoral condylar geometry is now available. It is believed that a G-curve design would lead to more mid-flexion stability leading to reduced incidence of paradoxical anterior slide. The objective of this study was to assess the in vivo kinematics for subjects implanted with this type of TKA under various conditions of daily living. Methods Tibiofemoral kinematics of 35 patients having posterior-stabilized TKA with G-curve design were analyzed using fluoroscopy while performing three activities: weight-bearing deep knee bend, gait, and walking down a ramp. The subjects were assessed for range of motion, condylar translation, axial rotation, cam-spine engagement, and condylar lift-off. Results The average weight-bearing flexion during deep knee bend was 111.4°. On average, the subjects exhibited 5.4 mm of posterior rollback of the lateral condyle and 2.0 mm of the medial condyle from full extension to maximum knee flexion. The femur consistently rotated externally with flexion, and the average axial rotation was 5.2°. Overall movement of the condyles during gait and ramp-down activity was small. No incidence of condylar lift-off was observed. Conclusion Subjects in this study experienced consistent magnitudes of posterior femoral rollback and external rotation of the femur with weight-bearing flexion. The variation is similar to that previously reported for normal knee where the lateral condyle moves consistently posterior compared to the medial condyle. Subjects experienced low overall mid-flexion paradoxical anterior sliding and no incidence of condylar lift-off leading to mid-flexion stability.

Regional variations in hospital billing for total joint arthroplasty (TJA) have been reported. It is not clear whether differences exist in hospital charges for TJA based on hospital profit status.Data from the Centers for Medicare and Medicaid Services on Medicare Severity-Diagnosis Related Groups (MS-DRGs) 469 (TJA with comorbidity) and 470 (TJA without comorbidity) for fiscal year 2011 were analyzed. Differences in hospital charges and payments were investigated based on hospital profit status (nonprofit, government, and proprietary). Generalized estimating equations determined differences in charges and reimbursement between hospital types controlling for census region, MS-DRG, and number of discharges.Significant differences in billing between institutions existed with median average hospital charges for nonprofit, government, and proprietary institutions being $70,514.30, $73,540.99, and $113,203.77 (P.0001), respectively, for DRG 469 and $45,363.95, $44,956.57, and $62,715.39 (P .0001), respectively, for DRG 470. Median average Centers for Medicare and Medicaid Services payments for nonprofit, government, and proprietary institutions for DRG 469 were $22,334.34, $21,346.65, and $21,281.30 (P = .017), respectively, and $14,461.95, $14,466.04, and $13,733.62 (P .0001), respectively, for DRG 470. Multivariate analyses indicate that nonprofit hospitals charge 5% more (P = .021) and receive 3% less (P = .011) reimbursement than government hospitals. Proprietary hospitals charge 34% more (P.0001) and receive 7% less (P.0001) reimbursement than government hospitals.Significant differences in hospital charges based on institution profit status were found, with proprietary institutions charging significantly more than nonprofit and government institutions. However, proprietary institutions had the lowest median average reimbursement.

Background The presence of pain as a harbinger of bearing-related problems has recently been challenged. Adverse local tissue reactions (ALTRs) have been noted on cross-sectional imaging even in asymptomatic patients. The purpose of this study was to determine the natural history of such lesions in asymptomatic patients. Methods Eighty-three asymptomatic patients with modular metal-on-metal total hip arthroplasties underwent metal ion reports and metal artifact reduction sequence magnetic resonance imaging (MARS MRI). MARS MRI images were reviewed and evaluated for the presence or absence of an ALTR lesion by a musculoskeletal radiologist and the senior author. We defined an ALTR lesion as abnormal fluid collections, solid or semisolid pseudotumors, or muscle or bone damage and was classified according to the MRI Classification System of Hart et al. In addition, serum cobalt and chromium levels were measured and analyzed at the time of MRI. Results Twenty-six of 83 (31%) asymptomatic patients had cystic lesions identified. All patients with positive MRIs were contacted to have repeat studies a year later. Nineteen of 26 were available for follow-up. Three patients who became symptomatic were revised. Most ALTRs in asymptomatic patients with modular metal-on-metal total hip arthroplasties that underwent repeat MARS MRI decreased in size (15 of 19 [79%]); 3 lesions increased, whereas 1 remained the same. All patients in the series had Co and Cr ion levels below the threshold of 7 ppb. Conclusion Although most cystic lesions decreased in size, vigilance is still required as 3 patients became symptomatic requiring revision.

The intraoperative appearance of rapidly destructive osteoarthritis and septic arthritis can be similar. Three patients at our institution demonstrated preoperative or intraoperative findings potentially consistent with infection during primary total hip arthroplasty; however, none of these patients were found to have an actual infection. One of these patients underwent an unnecessary 2-stage total hip arthroplasty secondary to the intraoperative appearance of their joint fluid. We advocate performing an infection workup preoperatively when patients present with rapid degenerative changes of their hip joint to diminish the uncertainty of proceeding with arthroplasty.

We sought to compare the efficacy and cost of reinfusion drains vs tranexamic acid (TA) in primary total joint athroplasty (TJA) patients. We randomized 186 primary TJAs (71 hips, 115 knees) to standard drains (61/186), autologous reinfusion drains (60/186), or single dose (20 mg/kg) of TA (65/186). There was a statistically significant (P < .0001) less drop in hemoglobin levels (2.98 mg/dL; range, 0.5-6.10) in the TA group compared with standard drains (P < .0001) and reinfusion drains (P < .0061). There was no significant difference in transfusion rates. At $581.89, the unit cost of the reinfusion system is substantially higher than the standard drain ($7.56) and TA ($35.91/g). The results of this randomized controlled trial demonstrate that TA is more efficacious and provides cost savings compared with reinfusion drains as a blood management tool for TJA.

Revision total knee arthroplasty is becoming an increasingly common reconstructive procedure. As the number of primary total knee arthroplasties continues to increase on a yearly basis, the need for revision surgery will likewise increase exponentially. Therefore, it is important to determine the best surgical techniques to manage revision problems as they are encountered. Most major manufacturers of total knee replacement offer modular revision knee systems. They use modular augmentations to deal with tibial and femoral bone loss. Most also feature intramedullary jig systems to make accurate revision bone cuts. In addition, manufacturers provide a variety of stems to enhance fixation in revision situations. Variable length stems designed to engage in the metaphysis or diaphysis are commonly offered options. Offset stems are also available to deal with altered anatomy. This variety of stems can be implanted in a press-fit or cemented fashion.

Use of large-head metal-on-metal (MoM) bearing surfaces in total hip arthroplasty (THA) has created new and unique modes of failure for this type of articulation. These unique modes are in addition to the traditional modes of failure seen in conventional THA, which include instability, osteolysis, infection, iliopsoas tendinitis, aseptic loosening, and periprosthetic fracture. Ion levels and cross-sectional imaging are helpful when evaluating a MoM patient in the identification of adverse local tissue reactions. Unique modes of failure in MoM THA include tissue necrosis, metallosis-induced osteolysis, skin hypersensitivity reactions, and rarely systemic cobaltism. This article outlines the evaluation and treatment of modes of failure in MoM THA.

To determine the importance of MRI abnormalities in metal-on-metal (MoM) bearings, it is important to understand the baseline features of this diagnostic tool in conventional metal-on-polyethylene (MoP) bearings.What are the frequency, size, and types of MRI-documented adverse local tissue reactions in asymptomatic patients with MoP bearings?We recruited 50 patients 5 years after a MoP total hip arthroplasty from a pool of patients in our joint registry who had a Harris hip score of90. To be included, patients had to be without pain and have adequate radiographs. Our data set included 50 asymptomatic patients with MoP bearings who underwent a metal artifact reduction sequence MRI.MRI abnormalities were seen in 14 of 50 (28%) asymptomatic patients who were studied. Thirteen of the 14 abnormalities were cystic thin-walled lesions with a mean of 18 cm3 (range, 1-79 cm3).MRI abnormalities were noted in nearly one-third of asymptomatic patients with MoP bearings. Decisions concerning revision of MoM bearings should not be based on isolated MRI findings because MRI abnormalities are commonly seen regardless of bearing type. A number of factors should determine the need for intervention including pain, mechanical symptoms, abductor weakness, component type, component position, and ion levels as well as MRI findings.Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Risk adjustment is critical when any comparison of hospital or surgeon performance on patient outcomes is being measured. It is equally critical when developing alternative payment models. The purpose of risk adjustment is to level the playing field in making comparisons of outcome either against a benchmark or across individual providers, hospitals, or providers groups. The consequences of not leveling the playing field may lead to the inappropriate inference of high quality, that is outcomes are better not because of better quality but because the patients are healthier. Another consequence of not leveling the playing field is the inappropriate inference of low quality, that is outcomes are worse not because of lower quality but because patients are less healthy at the onset. Additionally, caring for those patients with the most severe problems is more expensive and this fact must be taken into account in any alternative payment model. It is critically important that risk adjustment is done properly so that access for patients with the most severe problems will be maintained.

Risk adjustment is critical when any comparison of hospital performance or surgeon performance on patient outcomes is being measured. The purpose of risk adjustment is to level the playing field in making comparisons of outcome either against the benchmark or across individual providers, hospitals, or provider groups. The consequences of not leveling the playing field may lead to the inappropriate inference of high quality, that is outcomes are better not because of better quality but because the patients are healthy. Additional consequence of not leveling the playing field is the inappropriate inference of low quality, that is outcomes are worse not because of lower quality but because patients are less healthy at the onset. Therefore, it is critically important that risk adjustment is done properly so that access for the patients with the most severe problems will be maintained. Surgeons and hospitals should not be discouraged from providing care for these individuals for fear of publicly reporting outcomes that are not properly risk adjusted. To that end, American Association of Hip and Knee Surgeons created a Risk Adjustment Task Force to collaborate with Center for Medicare and Medicaid Services in creating a more robust risk adjustment model to take into account clinical factors and severity of orthopedic disease.

Background Catastrophic varus collapse is an uncommon mechanism of failure in primary total knee arthroplasty (TKA). Varus collapse has been associated with obesity and smaller implant sizes. However, to our knowledge, preoperative radiographic characterization of this cohort has not been performed. Therefore, the following study evaluated preoperative alignment and how this correlates with the degree of eventual varus collapse identified in this patient population prior to revision. Methods Utilizing our institutional database, 1106 revision TKAs were performed from 2004 to 2017. Of these, 35 patients were revised secondary to tibial varus collapse. Twenty-seven patients had their primary TKA performed at our institution. Coronal alignment of the knee was recorded from anteroposterior knee radiographs. Medial tibial bone loss was recorded at final follow-up. Results The average body mass index was 38 kg/m 2 . Twenty-six of 27 patients had a preoperative varus deformity (4.2° varus) and all were corrected to a valgus coronal alignment immediately postoperatively (5.2° valgus, P = .0001). Twenty-four of 27 patients' coronal alignment after varus collapse was within 2° of their preoperative alignment (5.8° varus). Twenty-five of 27 patients had radiographic medial tibial bone loss prior to varus collapse. Conclusion Tibial varus collapse in an uncommon cause of failure after primary TKA. Preoperative varus deformity, postoperative medial tibial bone loss, and obesity were common findings in this series of patients. Therefore, increased tibial stem lengths should be considered in patients with a preoperative varus deformity, small tibial implant size, and a body mass index ≥35 kg/m 2 undergoing primary TKA.

Background Custom triflange acetabular components are being increasingly used for the reconstruction of Paprosky type IIIB acetabular defects. However, midterm survivorship data are lacking. Methods We queried the prospective registries at 2 high-volume revision centers for patients who had undergone revision total hip arthroplasty using a custom triflange component between 2000 and 2011. We identified 73 patients with minimum 5-year follow-up. These patients' records were reviewed to determine incidence of revision or reoperation, clinical performance, and radiographic stability. The mean follow-up was 7.5 years (range 5-12 years). Results Fifteen of 73 triflange components (20.5%) were indicated for revision during the follow-up period, including 6 for instability (8%) and 8 for infection (11%). Twelve of 73 patients (16%) underwent reoperation for reasons other than failure of the triflange component. The median hip disability and osteoarthritis outcome score for joint replacement score at midterm follow-up was 85 (interquartile range 73-100). Only 1 of 73 implants was determined to be radiographically loose at midterm follow-up. Conclusion Custom triflange reconstruction for severe acetabular deficiency is a viable option; however, complications are common and significant challenges remain for those that fail.

Background The direct anterior approach for total hip arthroplasty (THA) is marketed with claims of superiority over other approaches. Femoral exposure can be technically challenging and potentially lead to early failure. We examined whether surgical approach is associated with early THA failure. Methods A retrospective review of 478 consecutive early revision THAs performed within 5 years after the primary THAs at 3 academic centers from 2011 through 2014 was carried out. Exclusion criteria resulted in a final analysis sample of 342 early-failure THAs. The surgical approach of the primary operation that was revised, the time to the revision, and the etiology of the failure leading to the revision were documented. Results Analysis of the revisions due to early femoral failure showed them to be more common in patients who had undergone the direct anterior approach (57/112; 50.9%) than in those treated with the direct lateral (39/112; 34.8%) or the posterior (16/112; 14.3%) approach (p = 0.001). In multivariate regression analysis controlling for age, sex, laterality, Dorr bone type, body mass index (BMI) at revision, bilateral procedure (yes/no), and femoral stem type, the direct anterior approach remained a significant predictor of early femoral failure (p = 0.007). The majority of early revisions due to instability were associated with the posterior (19/40; 47.5%) or direct anterior (15/40; 37.5%) approach (p = 0.001 for the comparison with the direct lateral approach [6/40; 15.0%]). Conclusions Despite claims of earlier recovery and improved outcomes with the direct anterior approach for THA, our findings indicate that that approach may confer a greater risk of early femoral failure and, along with the posterior approach, confer a greater risk of early instability compared with the direct lateral approach. Level of evidence Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

The interest in large head metal-on-metal (MoM) bearing surfaces in total hip arthroplasty (THA) has created new and unique modes of failure. When evaluating the patient with a painful MOM bearing, traditional failure mechanisms include instability, osteolysis, infection, iliopsoas tendinitis, aseptic loosening, and periprosthetic fracture must be ruled out first. Referred pain must also be ruled out at the time of evaluation of the problematic MoM THA. Unique modes of failure in MoM THAs include tissue necrosis, metallosis-induced osteolysis, skin hypersensitivity reactions, and on rare occasion systemic cobaltism. Early recognition of such reactions is important and poses a diagnostic challenge. Beyond the debris generated at the MoM articulation, corrosion at any modular junction within the hip system can be a contributor to metallosis-induced ALTRs. Serum metal levels and cross-sectional imaging are helpful when evaluating the patient with a MOM bearing in the identification of adverse local tissue reactions (ALTRs). This chapter outlines the evaluation and treatment of complications associated with MoM THAs.

Although regional variations in Medicare spending are known, it is not clear whether regional variations exist in hospital charges for total joint arthroplasty. Data from Centers for Medicare and Medicaid Services (CMS) on Diagnosis Related Groups 469 and 470 (Major Joint with and without Major Complicating or Comorbid Condition) from 2011 were analyzed for variation by region. Drastic variations in charges between institutions were apparent with significant differences between regions for hospital charges and payments. The median hospital charge nationwide was $71,601 and $46,219 for Diagnosis Related Groups 469 and 470, respectively, with corresponding median payments of $21,231 and $13,743. Weak to no correlation was found between hospital charges and payments despite adjustments for wage index, cost of living, low-income care and teaching institution status.

Total knee arthroplasty occasionally does not meet expectations. This randomized clinical trial assessed the effect of restoration of the native patellofemoral height on clinical outcomes. Group I underwent standard patellar bone resection; group II underwent modified patellar bone resection that adjusted the amount of anterior condylar bone removed and the anterior flange thickness. There were no differences in anterior knee pain, Western Ontario and McMaster Universities Arthritis Index scores, or Knee Injury and Osteoarthritis Outcome Score scores. Patellofemoral compartment height restoration versus patellar height alone does not appear to significantly reduce pain or improve function.

Prosthetic joint infection is devastating complication of total joint arthroplasty and represents a significant burden both financially and to the patient's overall health. Challenges are in part due to difficulty in eradicating the disease and that there is no census in the most economical and effective techniques for treatment. In the United States the treatment standard is a 2-stage exchange in which the components are removed and an antibiotic spacer is placed, several weeks of intravenous antibiotics, and then a second procedure to remove the antibiotic spacer and place the final components. A 1-stage exchange removes the infected components and places new components in the same surgical setting. The success rate are similar between the 2 options but to date no large scale randomized study has been performed, however a 1-stage exchange limits the total number operations, decreases the morbidity associated in between stages, and is associated with a decrease in overall cost. Surgeons treating prosthetic joint infections should consider this technique.

Introduction Prosthetic knee instability is a common cause of patient dissatisfaction and early failure after total knee arthroplasty (TKA). Strategies to manage such instability are dependent on the recognition of the presenting instability pattern because some require full revision, whereas others can be managed by polyethylene exchange (PE) only. This retrospective chart review classifies and reports on a series of patients where PE only was used to manage an unstable TKA. Methods Of 1606 revision TKA patients, 4% underwent an isolated PE for prosthetic knee instability. All cases were classified using the novel OrthoCarolina Prosthetic Knee Instability Classification System. This classification system was established to guide surgeons in the diagnosis and surgical management of periprosthetic knee instability. The final data set included 41 patients at an average follow-up of 43 months. Results Of the patients treated with poly exchange only for an appropriate indication (ie, coronal instability with competent ligaments or global instability), 63% felt their knee was stable, whereas 37% felt they remained unstable after revision. Additionally, only 59% had improvement in their pain, whereas 41% were dissatisfied with their pain relief after revision. Discussion Despite the use of this technique when indicated, the results of PE only with regard to pain and instability are unpredictable. Only approximately 50% of patients became stable and had adequate pain relief. Patients and surgeons alike should understand that this low morbidity option does not guarantee a good result regardless of whether it is used for an appropriate indication. Obtaining stability and pain relief in a patient with prosthetic knee instability remains a significant challenge. Therefore, the key to avoiding prosthetic knee instability is through prevention at the time of primary surgery. Prosthetic knee instability remains difficult to manage despite intuitive and appropriate indications for PE only.

Documentation of medical necessity for arthroplasty has come under scrutiny by Medicare. In some jurisdictions three months of physical therapy prior to arthroplasty has been mandated. The purpose of this study was to determine the efficacy and cost of this policy to treat advanced osteoarthritis. A systematic review was performed to assimilate efficacy data for physical therapy in patients with advanced osteoarthritis. The number of arthroplasties performed annually was obtained to calculate cost. Evidence-based studies documenting the efficacy of physical therapy in treating advanced arthritis are lacking with a potential cost of 36-68 million dollars. Physical therapy mandates by administrative contractors are not only ineffective but are costly without patient benefit. Medical necessity documentation should be driven by orthopedists not retroactively by Medicare contractors.

As the number of primary total hip arthroplasty (THA) procedures performed continues to rise, the burden of revision THA procedures is also expected to increase. Proper evaluation and management of acetabular bone loss at the time of revision surgery will be an increasing challenge facing orthopaedic surgeons. Proper preoperative patient assessment and detailed preoperative planning are essential in obtaining a good clinical result. Appropriate radiographs are critical in assessing acetabular bone loss, and specific classification schemes can identify bone loss patterns and guide available treatment options. Treatment options include impaction grafting and cementation of the acetabulum, noncemented hemispheric acetabular reconstruction, structural allograft reconstruction, noncemented reconstruction with modular porous metal augments, ring and cage reconstruction, oblong cup reconstruction, cup-cage reconstruction, and triflange reconstruction.

Knee osteoarthritis (OA) accounts for more functional disability of the lower extremity than any other disease. We recruited 18 patients with knee OA and 18 healthy age-, height-, mass-, and gender-matched control subjects to investigate the effects knee OA has on select spatial and temporal gait variables during a stair climbing task. No group-by-direction interaction was observed; however, significant effects did occur for group and direction. Specifically, patients with knee OA demonstrated less time in single support, greater time in double support, decreased step length, greater step width, less stride length, decreased total gait velocity, greater total time in support, and less total time in swing, compared with controls. Early-stage knee OA directly influences specific temporal and spatial gait characteristics during stair climbing.

Pelvic discontinuity is an increasingly common complication of THA. Treatments of this complex situation are varied, including cup-cage constructs, acetabular allografts with plating, pelvic distraction technique, and custom triflange acetabular components. It is unclear whether any of these offer substantial advantages.We therefore determined (1) revision and overall survival rates, (2) discontinuity healing rate, and (3) Harris hip score (HHS) after treatment of pelvic discontinuity with a custom triflange acetabular component and (4) the cost of this reconstructive operation compared to other constructs.We retrospectively reviewed 57 patients with pelvic discontinuity treated with revision THA using a custom triflange acetabular component. We reviewed operative reports, radiographs, and clinical data for clinical and radiographic results. We also performed a cost comparison with utilization of other techniques. Minimum followup was 24 months (average, 65 months; range, 24-215 months).Fifty-six of 57 (98%) were free of revision for aseptic loosening at latest followup. Fifty-four (95%) were free of revision of the triflange component for any reason. Thirty-seven (65%) were free of revision for any reason. Twenty-eight (49%) were free of revision for any reason and free of any component migration and had a healed discontinuity. Forty-six (81%) had a stable triflange component with a healed pelvic discontinuity. Average HHS was 74.8. The costs of the custom triflange implants and a Trabecular Metal cup-cage construct were equivalent: $12,500 and $11,250, respectively.In this group of patients with osteolytic pelvic discontinuity, triflange implants provided predictable mid-term fixation at a cost equivalent to other treatment methods.Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Utilization of the direct anterior approach (DAA) for total hip arthroplasty (THA) has increased in the last decade with fluoroscopy often used to confirm implant position, leg length, and offset. Radiation exposure thresholds around 800 mGy are published for the risk of cataracts. We hypothesized that surgeon eye exposure during fluoro-assisted DAA total hip arthroplasty would be well below these published thresholds.Three experienced orthopedic surgeons performed 30 consecutive fluoro-assisted DAA THAs. During each procedure, the surgeon wore a helmet-mounted dosimeter. After 30 consecutive cases, the dosimeters were analyzed. A chart review was then completed to obtain fluoroscopic data saved for each individual case including fluoroscopic time, total radiation dose, and radiation tech experience.Fluoroscopic data were available for 89 of 90 cases (98.8%). Surgeon 1 had an average fluoroscopic time of 18.51 seconds, radiation dose of 2.396 mGy, and tech experience of 13.06 years. Surgeon 2 had an average fluoroscopic time of 15.63 seconds, radiation dose of 2.139 mGy, and tech experience of 23.69 years. Surgeon 3 had an average fluoroscopic time of 11.06 seconds, radiation dose of 1.462 mGy, and tech experience of 16.03 years. The dosimeter results were 8, 5, and1 mrem, respectively, for each surgeon. The mean total radiation dose per case for all surgeons was 2.00 mGy (±1.31), and there was no correlation between radiation dose and radiologic tech experience (0.089, P.05) or radiation dose and patients' body mass index (0.260, P = .014).Each surgeon would need to perform300,000 DAA THAs to exceed the 800-mGy cataract threshold dose. The decision to wear protective glasses should be at the surgeon's discretion; however, the findings in this study show a very low radiation dose to the surgeon's eye regardless of radiologic tech experience or patient's body mass index.

The ASR (articular surface replacement) XL (DePuy, Warsaw, Ind) metal-on-metal hip arthroplasty offers the advantage of stability and increased motion. However, an alarming number of early failures prompted the evaluation of patients treated with this system. A prospective study of patients who underwent arthroplasty with the ASR XL system was performed. Patients with 2-year follow-up or any revision were included. Failure rates, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores, and radiographs were evaluated. Ninety-five patients (105 hips) were included. There were 16 revisions. Thirteen (12%) were aseptic acetabular failures. Eight were revised for aseptic loosening; 4, for metallosis; 1, for malposition; 2, for infection; and 1, for periprosthetic fracture. Mean time to revision was 1.6 years (0.18-3.4 years). The ASR XL with a revision rate of 12% is the second reported 1 piece metal-on-metal system with a significant failure rate at early follow-up. This particular class of implants has inherent design flaws that lead to early failure.

Irrigation and debridement (I&D) is an attractive treatment alternative for periprosthetic joint infection (PJI). Irrigation and debridement failure rates average 64% (range, 10.5%-84%) and may be associated with causative organism type and virulence. The study objective was to compare revision rates for PJI caused by streptococcal organisms to other organisms treated with I&D. A multicenter retrospective cohort study of 200 consecutive PJIs treated with I&D was performed. Failure was defined as reoperation for PJI. Failure rate for streptococcal infections was 65% (20/31) compared with 71% (84/119) for other organisms. Failure rate for sensitive Staphylococcus was 72% (48/67) compared with a 76% (22/29) failure rate for resistant Staphylococcus. These results indicate that eradication rates of I&D for a streptococcal PJI are comparable with other causative organisms. Irrigation and debridement should play a limited role in the PJI treatment algorithm regardless of organism type.

Patellar crepitus (PC) is reported in up to 14% of subjects implanted with cruciate-substituting total knee arthroplasty (TKA). Numerous etiologies of PC have been proposed.We determined when painful PC typically occurs postoperatively and compared patients undergoing primary TKA who developed painful PC requiring subsequent surgery with a matched group without this complication to identify clinical, radiographic, and surgical variables associated with this complication.From the databases of two institutions (greater than 4000 TKAs), we identified 60 patients who required surgery for painful PC from 2002 to 2008. This group was then compared with an identified control group of 60 TKA subjects without PC who were matched for the key variables of age, gender, and body mass index to determine clinical, radiographic, and surgical factors associated with the development of PC.The mean time to presentation of PC was 10.9 months. The incidence of PC correlated with a greater number of previous knee surgeries, decreased patellar component size, decreased composite patellar thickness, shorter preoperative and postoperative patellar tendon length, increased posterior femoral condylar offset, use of smaller femoral components and thicker tibial polyethylene inserts, and placement of the femoral component in a flexed posture.Many of the factors associated with an increased incidence of postoperative PC such as shortened patellar tendon length, use of smaller patellar components, decreased patellar composite thickness, and increased posterior femoral condylar offset may all increase quadriceps tendon contact forces against the superior aspect of the intercondylar box, increasing the risk of fibrosynovial proliferation and entrapment within the intercondylar region of the femoral component. Based on these findings, the authors recommend use of larger patellar components when possible, avoid oversection of the patella or increasing posterior femoral condylar offset, and advising patients preoperatively who have had previous knee surgery or demonstrate a shortened patellar tendon length of an increased risk of development of postoperative patellar crepitus.Level III, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Demand for primary and revision arthroplasty is expected to double in 10 years. Coincident with this is a decreased interest in arthroplasty by residents. Retirement of arthroplasty surgeons further threatens access. This study determines if supply will meet demand. Survey data were used to calculate the 2016 workforce. Demand in 2016 was estimated using the Nationwide Inpatients Sample. Between 2008 and 2016, 400 arthroplasty specialists and 1584 generalists will enter the workforce. By 2016, 1896 arthroplasty surgeons will retire using 65 years as a conservative retirement age, whereas 4239 will retire using 59 years as a baseline retirement age. In 2016, the model estimated a procedural shortfall ranging from 174,409 (↓18.6%) using conservative retirement assumptions (age, 65 years) to 1,177,761 (↓69.4%) using baseline retirement assumptions (age, 59 years). This economic model predicts a supply side crisis that threatens patient access to specialty care. Immediate steps to stimulate supply must be taken.

To evaluate the effects of the economic downturn on adult reconstruction surgery in the United States, a survey of the American Association of Hip and Knee Surgeons (AAHKS) membership was conducted. The survey evaluated surgical and patient volume, practice type, hospital relationship, total joint arthroplasty cost control, employee staffing, potential impact of Medicare reimbursement decreases, attitudes toward health care reform options and retirement planning. A surgical volume decrease was reported by 30.4%. An outpatient visit decrease was reported by 29.3%. A mean loss of 29.9% of retirement savings was reported. The planned retirement age increased to 65.3 years from 64.05 years. If Medicare surgeon reimbursement were to decrease up to 20%, 49% to 57% of AAHKS surgeons would be unable to provide care for Medicare patients, resulting in an unmet need of 92,650 to 160,818 total joint arthroplasty procedures among AAHKS surgeons alone. Decreases in funding for surgeons and inadequate support for subspecialty training will likely impact access and quality for Americans seeking adult reconstruction surgery.

Despite the clinical success of modern metal-on-metal articulations, concerns with wear-related release of metal ions persist. Evidence suggests metal ion release is related to the effective coverage of the head in the metal shell (the cup's functional articular arc). A recent study suggests a reduced functional articular arc is associated with increased ion release and the arc is a function of component design, size, and the abduction angle.The purposes of this study were to (1) measure the functional articular arc in different sizes of currently available one-piece metal shells from several different manufacturers; and (2) compare the functional articular arc of these one-piece metal shells with the 180 masculine arc of conventional hip arthroplasty acetabular components.We calculated the available articular surface arc for 33 one-piece metal cups using measurements of cup depth and internal cup radius.The arc of the articular surface varied among manufacturers and generally decreased with decreasing shell diameter. The mean functional articular arc was 160.5 degrees +/- 3.6 degrees (range, 151.8 degrees -165.8 degrees), which was less than the 180 degrees arc of a conventional acetabular component.Our data show certain cup designs are at higher risk for failure as a result of the decreased articular surface arc. This, along with analysis of abduction angles, supports the recent findings of bearing failure with vertically placed implants. Care must be taken when implanting these shells to ensure they are placed in less abduction to avoid edge loading and the potential for early bearing failure.

Unicondylar arthroplasty has reemerged as an option for isolated compartment knee arthritis. We have noticed an increase in the need for early revision of this construct at our revision center. This study sought to determine if the need for unicondylar revision has increased over time and what factors may have led to early failure. Revision total knee arthroplasties (TKAs) performed between 1990 and 1999 (period 1) were compared to TKAs performed between 2000 and 2008 (period 2). The prevalence of unicondylar revision, time to failure, and reasons for failure were calculated. Between 1990 and 1999, 425 revision TKAs were performed, 7 of which were uni-revisions (1.6%). These had been in place an average of 169 months (range, 12.9–478.6 months). Between 2000 and 2008, 744 revision TKAs were performed, 43 of which were uni-revisions (5.8%). These had been in place an average of only 36 months (range, 4.2–159.5 months). The dominant reasons for failure in period 1 included poly wear and loosening. Reasons for failure in period 2 were variable but included a number of technical errors. Early failure of unicondylar arthroplasty appears to be on the rise. Acknowledging that these patients came from an unknown pool, we are concerned that market pressure may have led to inappropriate patient selection and that surgical inexperience with this procedure may have led to the technical problems noted in period 2. Patients should be apprised of the possibility of early revision with this procedure.

Background: Claims that there are dramatic differences in anterior condylar anatomy between the sexes have led to the design of total knee implants with thinner anterior condyles specifically for use in women. We had observed, in our patients, differences in anterior condylar anatomy that appeared to be highly variable and dependent on the size, height, and ethnicity of the patient as well as his or her sex. Because of this observed variability, we sought to determine if differences in anterior condylar anatomy between the sexes actually exist. Methods: Two hundred and twelve randomly selected magnetic resonance images (112 of men and 100 of women) were evaluated. The anterior condyle was defined as the area of bone anterior to the anterior femoral cortex, 10 mm above the joint line. The medial and lateral heights of the anterior condyles were measured in millimeters directly from magnetic resonance imaging data obtained in two planes. The so-called aspect ratio was calculated to determine whether patient size had an effect on the size of the anterior condyles. Results: On the basis of the numbers available, there was no significant difference (p = 0.16) between the sexes with regard to lateral condylar height. The average difference was only 0.5 mm. There was a significant difference (p = 0.001) between men and women with regard to medial condylar height. However, the average difference was only 1.1 mm. While the difference between the sexes with regard to anterior condylar height was nominal, the measurements were highly variable regardless of sex. On the basis of the numbers available, there were no significant differences between men and women with regard to the condylar aspect ratios. Conclusions: The difference in anterior condylar anatomy is mentioned as one of three reasons for the need for a so-called gender-specific knee implant. The aspect ratio reported here, which is a surrogate for patient size, seems to negate any difference in anterior condylar anatomy based on sex. We have shown that anterior condylar anatomy is highly variable regardless of sex. We believe that implants as well as surgical techniques should be designed with the variability of anterior condylar anatomy taken into account and with an attempt to reproduce such anatomy regardless of sex.

The study purpose was to analyze current results of modern cementless femoral components in young patients having total hip arthroplasty (THA) or hip resurfacing. Twenty-two studies (n = 5907; hips = 6408) evaluating modern cementless THA in young patients and 15 studies evaluating hip resurfacing (n = 3002; hips = 3269) were included. Meta-analysis techniques were used to pool failure rates. The pooled failure rate for THA using femoral revision for mechanical failure as an end point was 1.3% (95% confidence interval [CI], 1.0%-1.7%) at a mean 8.4 years of follow-up. At a mean of 3.9 years of follow-up, the pooled mechanical failure rate of the femoral component for hip resurfacing was 2.6% (95% CI, 2.0-3.4). In conclusion, the enthusiasm for hip resurfacing should be tempered by these data. Longer follow-up and direct comparison trials are required to confirm these findings.

The purpose of this study was to asses the fate of incomplete seating of press-fit acetabular components. From 1990 to 2002, 587 hip arthroplasties were performed using a single-design acetabular component inserted with a press-fit technique with no additional fixation. Complete radiographic follow-up at a mean 9.2 years was available for 343 cases. One hundred thirty-three acetabular components had incomplete seating on the initial postoperative radiograph and 210 cases had complete seating. Of 133 components, 125 (94%) had evidence of complete zone 2 filling. Zone 2 focal osteolysis was present in 22 patients. There were no intraoperative fractures. No acetabular components were revised for loosening. Incomplete seating of press-fit acetabular components is safe and effective in achieving initial and long-term fixation. Zone 2 lucencies when present initially are not associated with increased failure risks. Vigorous attempts to completely seat the acetabular component appear to be unwarranted.

Computer-assisted surgery (CAS) has been advocated as a means to improve limb and prosthesis alignment and assist in ligament balancing in total knee arthroplasty (TKA). Thus, we sought to examine alignment outcomes in CAS vs conventional TKA. A systematic review of literature from 1990 to 2007 was performed. Direct comparison of alignment outcomes was performed using random effects meta-analyses. Twenty-nine studies of CAS vs conventional TKA were identified, and included mechanical axis malalignment of greater than 3 degrees occurred in 9.0% of CAS vs 31.8% of conventional TKA patients. The risk of greater than 3 degrees malalignment was significantly less with CAS than conventional techniques for mechanical axis and frontal plane femoral and tibial component alignment. Tibial and femoral slope both showed statistical significance in favor of CAS at greater than 2 degrees malalignment. Meta-analysis of alignment outcomes for CAS vs conventional TKA indicates significant improvement in component orientation and mechanical axis when CAS is used.

UNLABELLED: We compared the incidence of wear-related failures between two large cohorts of patients undergoing total knee arthroplasty implanted with identical modular tibial trays and polyethylene inserts sterilized by different methods. A total of 1183 second-generation press-fit condylar prostheses having inserts packaged and sterilized in an oxygen-free environment were assessed at a minimum 5-year followup (mean, 7.0 years). Wear-related failure was defined as (1) osteolysis greater than 100 mm2 or (2) revision of the implant resulting from osteolysis, polyethylene wear, chronic synovitis, and/or effusion. Wear-related survivorship was calculated using Kaplan-Meier survival analysis. Results were compared with our previously published study of 1287 first-generation press-fit condylar modular knees having inserts sterilized by gamma irradiation in air at 5-year minimum followup (mean, 7.8 years). The wear-related failure rate for the second-generation design was 1.1% and 10-year survivorship was 97.0% compared with 8.3% failure and 87.7% 10-year survival for the first-generation design. For second-generation components, patient age was the only variable correlated with wear-related failure. For first-generation components sterilized in air, several variables were correlated to wear-related failure with shelf age of the polyethylene insert being the most important factor. These data emphasize the dramatic effect improvements in polyethylene manufacturing, specifically sterilization methods, can have on implant survivorship. LEVEL OF EVIDENCE: Level III, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

A retrospective review of patients with joint arthroplasty was performed to determine if body mass index has increased with time and if the body mass index of patients with arthroplasty was significantly different than that of the general population. We also sought to determine if reimbursement kept pace with this growing cohort. The number of obese patients increased from 30.4% in 1990 to 52.1% in 2005 (P < .0001). In 2005, 24% of the general population was obese, whereas 52.1% of arthroplasty patients were obese. Physician reimbursement decreased 38% for knee arthroplasty and 46% for hip arthroplasty and the need for total joint arthroplasty because of these confounding variables will increase exponentially beyond scheduled expectations. Patients and health policy forecasters must understand the interrelationship between obesity and the need for arthroplasty.

Background: Two-stage reimplantation is the most accepted mode of treatment for patients with a periprosthetic infection following total knee arthroplasty. Most studies, however, do not stratify their results on the basis of the type of infecting organism. The purpose of this study was to determine the outcomes for patients who had two-stage reimplantation for the treatment of infection with a resistant organism, methicillin-resistant Staphylococcus aureus or methicillin-resistant Staphylococcus epidermidis, at the site of a total knee replacement. Methods: A multicenter study was performed to review the cases of all patients treated between 1987 and 2003 because of an infection with methicillin-resistant Staphylococcus aureus or methicillin-resistant Staphylococcus epidermidis organisms at the site of a total knee replacement. The prevalence of reinfection following two-stage reimplantation was determined. Variables that may influence the outcome, such as the duration and type of intravenous antibiotics administered, previous surgery, and comorbidities of the host, were analyzed. Results: We identified thirty-seven patients who had an infection with a resistant organism. All patients had negative cultures at the time of reimplantation. Four of the thirty-seven patients had a reinfection with the same organism, while five had a reinfection with a different organism. None of the variables noted above were found to be significantly associated with reinfection, on the basis of the numbers available. Conclusions: Reports in the literature have discouraged reimplantation for the treatment of an infection with a resistant organism at the site of a total knee replacement. While 24% of the patients in this series had a reinfection, 14% had a reinfection with a different organism. We believe that two-stage reimplantation remains a viable treatment option for patients who have an infection with a resistant organism at the site of a total knee replacement. Level of Evidence: Therapeutic Level IV. See Instructions to Authors for a complete description of levels of evidence.

In 2009, the National Quality Forum (NQF) published the rates of complications following primary total hip replacement and total knee replacement; these complication rates across U.S. hospitals ranged from a mean of 2.2% to 8.9%, with a median prevalence of 4.2%1. The NQF concluded that “this variation likely indicates differences in quality of care received across hospitals.” In September 2012, the Centers for Medicare & Medicaid Services (CMS) issued preliminary hospital-specific reports of thirty-day risk-standardized readmission rates after elective primary total hip and/or knee arthroplasty and total adverse event rates2. CMS is now implementing routine, hospital-specific, public total joint replacement quality reports based on these measures to compare risk-adjusted thirty-day outcomes. The recent release of publicly reported total joint replacement outcomes illustrates the growing importance that public health officials place on measuring and comparing outcomes after total joint replacement across hospitals and surgeons. While the CMS methods represent an important first step, the CMS risk-adjustment methodology raises a number of concerns. First, the CMS models are based solely on administrative billing data and International Classification of Diseases, Ninth Revision (ICD-9) comorbidity codes and lack surgeon and patient-reported health information. Surgeon-reported clinical risk factors are often central to quality measurement systems, as highlighted in the coronary artery bypass grafting (CABG) outcome reports of the Society of Thoracic Surgeons3. To advocate for the addition of clinical risk factors in comparative data for total joint replacement, arthroplasty surgeons need a clearer understanding of key preoperative risk factors that influence postoperative outcomes. From the public perspective, it is important that patients with severe knee or hip conditions have full access to expert surgeons and be aware of the impact of their preoperative condition on outcomes. The second major limitation of the CMS reports is that the analyses are …

Prompt attention is typically required in managing intraoperative problems associated with total hip arthroplasty. There is often limited time for consultation or a review of the literature. The treating surgeon should be familiar with treatment options, favored treatment methods, and should be able to implement the most appropriate and optimal treatment for his or her patient. Common intraoperative complications associated with primary total hip arthroplasty include difficulty gaining sufficient exposure, problems with cup fixation, challenges with implant anteversion, intraoperative fracture of the femur, and difficulties with intraoperative limb length and hip instability.

UNLABELLED Revision total knee arthroplasty requires the removal of one or all of the prior knee components. Thoughtful and careful removal of well-fixed total knee components can preserve host bone stock and facilitate subsequent reconstructive efforts. The tools and techniques for knee component removal include simple osteotomes, saws, extraction devices, ultrasonic devices, and frequently a combination of some or all of the above. It is the unique nature of each revision arthroplasty, which presents the surgeon with such challenge. Each of the techniques discussed in this review reflects the anecdotal experience acquired in over 800 revision total knee arthroplasties performed at our center. We review our empiric bias regarding the individual applicability of these techniques. LEVEL OF EVIDENCE Therapeutic studies, Level V (expert opinion). See Guidelines for Authors for a complete description of Levels of Evidence.

The diagnosis of adverse local tissue reaction (ALTR) after metal-on-metal total hip arthroplasty (MoMTHA) presents a significant challenge. No single biomarker is specific for ALTR. The purpose of this study was to determine if the ratio of cobalt to chromium ions is useful for diagnosing ALTR in MoMTHA. In 89 bearing-related revision THAs, preoperative cobalt and chromium ion levels were compared to an intraoperative soft tissue damage grading scale. The average cobalt to chromium ratio was 2.96 (0–20). There was no correlation between the tissue scale and the cobalt to chromium ratio (R=0.095; P =0.41). Many variables affecting ion production/excretion mitigate the use of the ion ratio. The cobalt to chromium ratio is not a predictive biomarker for ALTR in MoMTHA.

The purpose of this study was to evaluate the economic attributes of private practice adult reconstruction (AR) offices. 458 AAHKS surgeons responded; 65% were in private practice (fee-for-service, non-salaried, non-employed AR surgeons). 54% had considered hospital employment in the past two years. The average group employs 13.4 orthopedic surgeons (3.4 AR), and 105 other employees. The average total budget is $12.5 million per year with $4 million in salaries, and $238,000 in tax revenue generated. Co-management joint ventures are a better model than hospital employment for aligning AR surgeons and hospitals and realizing the cost effectiveness and quality improvement goals of PPACA and AARA while preserving the economic impact of AR private practice.