Obesity Severity Predicts Patient Dissatisfaction After Total Knee Arthroplasty.

BACKGROUND: Patient dissatisfaction has been reported in 15 to 20% of traditional total knee arthroplasty (TKA) procedures. While contemporary improvements may have positive effects on patient satisfaction, these may be offset by increasing obesity prevalence among patients who have knee osteoarthritis. We performed this study to determine whether obesity severity impacts patient-reported TKA satisfaction. METHODS: We compared patient demographic characteristics, preoperative expectations, preoperative and minimum 1-year postoperative patient-reported outcome measures as well as postoperative satisfaction level among 229 patients (243 TKAs) who had World Health Organization (WHO) Class II or III obesity (group A), and 287 patients (328 TKAs) who had WHO classifications of normal weight, overweight, or Class I obesity (group B). RESULTS: Group A patients were younger and had more severe preoperative back and contralateral knee pain, more frequent preoperative opioid medication use, and lower preoperative and postoperative patient-reported outcome measures (P < .01). A similar proportion of patients in both groups expected at least 75% improvement (68.5 versus 73.2%, P = .27). While satisfaction was higher than traditional reporting for both groups (89.4 versus 92.6%, P = .19), group A patients were less likely to be highly satisfied (68.1 versus 78.5%, P = .04) and were more likely to be highly dissatisfied (5.1 versus 0.9%, P < .01). CONCLUSIONS: Patients who have Class II and III obesity report greater TKA dissatisfaction. Additional studies should help determine whether specific implant designs or surgical techniques may improve patient satisfaction or whether preoperative counseling should incorporate lower satisfaction expectations for patients who have WHO Class II or III obesity.

Outcomes of Total Knee Arthroplasty Revisions in Obese and Morbidly Obese Patient Populations.

BACKGROUND: The obese population is at higher risk for complications following primary total knee arthroplasty (TKA), but little data is available regarding revision outcomes. This study aimed to investigate the role of body mass index (BMI) in the cause for revision TKA and whether BMI classification is predictive of outcomes. METHODS: A multi-institutional database was generated, including revision TKAs from 2012 to 2019. Data collection included demographics, comorbidities, surgery types (primary revision, repeat revision), reasons for revision, lengths of hospital stay, and surgical times. Patients were compared using 3 BMI categories: nonobese (18.5 to 29.9), obese (30 to 39.9), and morbidly obese (≥40). Categorical and continuous variables were analyzed using chi-square and 1-way analysis of variance tests, respectively. Regression analyses were used to compare reasons for revision among weight classes. RESULTS: Obese and morbidly obese patients showed significant risk for repeat revision surgery in comparison to normal weight patients. Obese patients were at higher risk for primary revision due to stiffness/fibrosis and repeat revision due to malposition. In comparison to the obese population, morbidly obese patients were more likely to require primary revision for dislocation and implant loosening. CONCLUSION: Significant differences in primary and repeat revision etiologies exist among weight classes. Furthermore, obese and morbidly obese patients have a greater risk of requiring repeat revision surgery. These patients should be informed of their risk for multiple operations, and surgeons should be aware of the differences in revision etiologies when anticipating complications following primary TKA.

Conversion Total Knee Arthroplasty After Failed Osteochondral Allograft Reconstruction: Similar Functional Performance With Lower Patient Satisfaction.

BACKGROUND: This study presents surgical techniques used in conversion total knee arthroplasty (cTKA) following early failure of large osteochondral allograft joint replacement and compares postoperative patient reported outcomes measures (PROMs) and satisfaction scores with a contemporary primary total knee arthroplasty (pTKA) cohort. METHODS: We retrospectively evaluated 25 consecutive cTKA patients (26 procedures) to define the utilized surgical techniques, radiographic disease severity, preoperative and postoperative PROMs (visual analog scale [VAS] pain, knee injury and osteoarthritis outcome score for joint replacement [KOOS-JR], University of California Los Angeles Activity), expected improvement and postoperative satisfaction (5-point Likert), and reoperations in comparison with an age and body mass index propensity matched cohort of 50 pTKA performed for osteoarthritis (52 procedures). RESULTS: Revision components were used in 12 cTKA cases (46.1%), with 4 cases requiring augmentation (15.4%), and 3 cases utilizing varus-valgus constraint (11.5%). While no significant differences were noted in expectation level or in other PROMs, mean patient reported satisfaction was lower in the conversion group (4.4 ± 1.1 versus 4.8 ± 0.5 points, P = .02). High cTKA satisfaction was associated with a higher postoperative KOOS-JR (84.4 versus 64.2 points, P = .01) and a trend towards higher University of California Los Angeles activity (6.9 versus 5.7 points, P = .08). Four patients in each group underwent manipulation (15.3 versus 7.6%, P = .42), and 1 pTKA patient was treated for early postoperative infection (0 versus 1.9%, P = 1.0). CONCLUSION: cTKA following failed biological replacement was associated with similar postoperative improvement as in pTKA. Lower patient-reported cTKA satisfaction was associated with lower postoperative KOOS-JR scores.

Tobacco Use Is Associated with More Severe Adverse Outcomes Than Morbid Obesity after Aseptic Revision TKA.

The association of morbid obesity with increased revision total knee arthroplasty (rTKA) complications is potentially confounded by concurrent risk factors. This study was performed to evaluate whether morbid obesity was more strongly associated with adverse aseptic rTKA outcomes than diabetes or tobacco use history-when present as a solitary major risk factor. Demographic characteristics, surgical indications, and adverse outcomes (reoperation, revision, infection, and amputation) were compared between 270 index aseptic rTKA performed for patients with morbid obesity (n = 73), diabetes (n = 72), or tobacco use (n = 125) and 239 "healthy" controls without these risk factors at a mean 75.7 (range: 24-111) months. There was no difference in 2-year reoperation rate (17.8 vs. 17.6%, p = 1.0) or component revision rate (8.2 vs. 8.4%) between morbidly obese and healthy patients. However, higher reoperation rates were noted in patients with diabetes (p = 0.02) and tobacco use history (p < 0.01), including higher infection (p < 0.05) and above knee amputation (p < 0.01) rates in patients with tobacco use history. Multivariate analysis retained an independent association between smoking history and amputation risk (odds ratio: 7.4, 95% confidence interval: 1.7-55.2, p < 0.01). Morbid obesity was not associated with an increased risk of reoperation or component revision compared with healthy patients undergoing aseptic revision. Tobacco use was associated with increased reoperation and above knee amputation. Additional study will be beneficial to determine whether risk reduction efforts are effective in mitigating postoperative complication risks.

Blood Transfusion can be Avoided in Single-Anesthetic Bilateral Total Knee Arthroplasty.

BACKGROUND: Female gender and surgical drain use have been associated with an increased transfusion risk following single-anesthetic bilateral total knee arthroplasty (SBTKA). This study evaluated allogenic blood transfusion rates among female and male patients undergoing SBTKA with intraoperative tourniquet, tranexamic acid and contemporary blood transfusion thresholds but without surgical drain use. METHODS: We performed a retrospective electronic medical record review for 125 consecutive patients undergoing SBTKA (250 knees) between May 1, 2015 and July 10, 2021. Patient demographic characteristics (age, gender, body mass index, American Society of Anesthesiologists), preoperative and postoperative hemoglobin levels, perioperative transfusions, operative time, and hospital length of stay were compared between 76 female (60.8%) and 49 male (39.2%) patient cohorts using paired Student's t-test or Fisher's exact test with a P value <.05 for significance. RESULTS: No patient in either gender-based cohort received a perioperative allogeneic or autologous blood transfusion (P = 1). There were no significant differences in patient demographic features or medical comorbidities. Male patients had significantly higher mean preoperative (14.7 versus 13.7 g/dL, P < .01) and postoperative (12.7 versus 11.8 g/dL, P < .01) hemoglobin levels and a shorter mean hospital length of stay (2.5 versus 3.0 days, P < .01). There was no difference in the mean operative time (154.7 versus 150.7 minutes, P = .34) or change in the hemoglobin level (2.1 versus 1.9 g/dL, P = .27). CONCLUSION: SBTKA can be performed with a limited risk of perioperative transfusion with a combination of intraoperative tourniquet, tranexamic acid, conservative blood transfusion criteria, and avoidance of postoperative drain use. Study results were not influenced by patient gender. LEVEL OF EVIDENCE: This is a level III, retrospective cohort study.

Cemented Patellar Implant Malposition: A Non-Issue for the Painful Total Knee Arthroplasty.

BACKGROUND: Non-optimal patellofemoral relationships may influence treatment decisions during revision total knee arthroplasty (TKA). We performed this study to determine whether patellar implant malposition or patellar tilt is associated with inferior patient-reported outcome scores or patient satisfaction after primary TKA. METHODS: We identified 396 TKA patients (439 knees) from an institutional registry who had undergone patellar resurfacing, with preoperative and 6-week postoperative radiographs available, and patient-reported outcome measures (PROMs) completed at least 1 year after surgery (mean 505 days). Preoperative patient demographic characteristics, patient-reported expectations, National Institutes of Health - Patient Reported Outcomes Measurements Instrument Systems global health, Knee Injury and Osteoarthritis Outcome Score for Joint Replacement, and University of California Los Angeles activity scores were compared between 60 TKAs performed with non-optimal patellofemoral relationships (36 patellar implant malposition, 24 patellar tilt) and 379 TKAs performed with optimal patellar implant placement. RESULTS: There were no differences between the 2 cohorts regarding demographic features, preoperative radiographic disease severity, expectations, and PROMs; or postoperative tibiofemoral component alignment, PROMs, and patient-reported satisfaction (P = .48). Knee Injury and Osteoarthritis Outcome Score for Joint Replacement improved similarly (P = .62) for patients with optimal resurfacing (48.5-77.6 points) and non-optimal resurfacing (47.7-76.6 points). A similar proportion of optimal and suboptimal resurfaced patients reported being satisfied with their TKA (92.7% vs 88.1%, P = .29). CONCLUSION: Although suboptimal patellofemoral relationships may prompt treatment considerations during revision TKA, the data obtained from this study do not suggest that patellar implant malposition or patellar tilt independently contribute to postoperative pain, functional limitation, or dissatisfaction. LEVEL OF EVIDENCE: This is a level III, retrospective cohort study.

Isolated Liner Revision for Total Knee Arthroplasty Instability: A Road That Should Remain Less Taken.

Isolated polyethylene liner exchange (IPLE) is infrequently selected as a treatment approach for patients with primary total knee arthroplasty (TKA) prosthetic joint instability. Potential advantages of less immediate surgical morbidity, faster recovery, and lower procedural cost need to be measured against reoperation and re-revision risk. Few published studies have directly compared IPLE with combined tibial and femoral component revision to treat patients with primary TKA instability. After obtaining institutional review board (IRB) approval, we performed a retrospective comparison of 20 patients treated with IPLE and 126 patients treated with tibial and femoral component revisions at a single institution between 2011 and 2018. Patient demographic characteristics, medical comorbidities, time to initial revision TKA, and reoperation (90 days, <2 years, and >2 years) were assessed using paired Student's t-test or Fisher's exact test with a p-value <0.01 used to determine significance. Patients undergoing IPLE were more likely to undergo reoperation (60.0 vs. 17.5%, p = 0.001), component revision surgery (45.0 vs. 8.7%, p = 0.002), and component revision within 2 years (30.0 vs. 1.6%, p < 0.0001). Differences in 90-day reoperation (p = 0.14) and revision >2 years (p = 0.19) were not significant. Reoperation for instability (30.0 vs. 4.0%, p < 0.001) and infection (20.0 vs. 1.6%, p < 0.01) were both higher in the IPLE group. IPLE does not provide consistent benefits for patients undergoing TKA revision for instability. Considerations for lower immediate postoperative morbidity and cost need to be carefully measured against long-term consequences of reoperation, delayed component revision, and increased long-term costs of multiple surgical procedures. This is a level III, case-control study.

Dual Antibiotic Prophylaxis in Primary Total Knee Arthroplasty-No Benefit for Extremely Obese Patients.

We performed this study to assess the effectiveness of multimodal total knee arthroplasty prosthetic joint infection (TKA-PJI) prophylaxis including "on-time" dual-antibiotic prophylaxis, and the influence of body mass index (BMI) on prophylaxis effectiveness. After obtaining Institutional Review Board approval, we assessed 1,802 primary TKAs (1,496 patients) who received cefazolin alone or cefazolin combined with vancomycin for TKA-PJI prophylaxis. A detailed chart review was performed to determine patient demographic features (age, gender, BMI, American Society of Anesthesiologists Score), antibiotic selection, vancomycin administration timing, and 1-year PJI rates. Statistical assessment was accomplished using a two-sided Student's t-test or Fisher's exact test. Patients who received dual-antibiotic prophylaxis with "on time" vancomycin infusion (Group CVt) had significantly lower infection rates than other TKA patients (0.8 vs. 2.7%, p < 0.01). "On Time" vancomycin administration was associated with a lower TKA-PJI rate for patients with a BMI < 45 kg/m2 (0.5 vs. 2.6%, p < 0.01) with no infections in 120 TKA patients with a BMI between 40 and 44.9 kg/m2 (p < 0.01). No difference was noted for patients with a BMI ≥ 45 kg/m2 (3.3 vs. 2.6%, p = 0.71). There were no infections in 150 TKA patients with a normal BMI (18-25 kg/m2) in any PJI-prophylaxis treatment group. Adoption of a dual-antibiotic prophylaxis approach can successfully reduce TKA-PJI rates among overweight and moderately obese patients. The approach does not appear to influence outcomes for low risk patients with a normal BMI (18-25 kg/m2) or for higher risk patients with a BMI > 45 kg/m2.

Revision TKA for Instability: Poorer Outcomes after a Previous Aseptic Revision.

Instability is a common indication for early revision total knee arthroplasty (rTKA). The comparative performance of instability rTKA performed after primary TKA and instability rerevision TKA (rrTKA) performed after a previous rTKA performed for any aseptic indication have not been defined. This study was performed to determine the rate of adverse outcomes for patients undergoing aseptic instability TKA revision following a primary TKA or a previous aseptic any-cause rTKA. After obtaining Institutional Review Board approval, we retrospectively identified 126 rTKA and 28 rrTKA component revision procedures performed for an exclusive instability diagnosis between January 1, 2011 and April 30, 2018. We excluded patients undergoing isolated liner exchange, single component revision for mid-flexion instability, and patients treated with a constrained hinge. Patient demographic characteristics, medical comorbidities, time to initial revision TKA, and adverse postrevision outcomes (reoperation, component revision, infection, amputation) were assessed using paired Student's t-test or Fisher's exact test with a p-value < 0.05 used to determine significance. Patients in the rrTKA cohort were more commonly female (57.1 vs. 27.8%, p < 0.01), with no other demographic differences. The rrTKA cohort had higher reoperation (39.3 vs. 18.4%, p = 0.02) and component revision rates (25.0 vs. 8.7%, p = 0.03), with a trend towards early reoperation < 2 years after surgery (25.0 vs. 11.1%, p = 0.07). The rrTKA cohort also had higher adverse outcomes related to infection (14.3 vs. 1.6%, p = 0.01), extensor mechanism failure (14.3 vs. 3.2%, p = 0.04) and above-knee amputation (14.3 vs. 2.4%, p = 0.02). Component revision is beneficial for patients with TKA instability; however, higher adverse outcome rates occur after instability rrTKA performed after a previous aseptic any-cause rTKA. Infection prevention and extensor mechanism protection are important to minimize the most common adverse outcomes identified among patients undergoing aseptic rrTKA for instability.

Tibial Bone Quality in Former Bariatric Surgery Patients with Osteoarthritis.

Downstream effects of bariatric weight-loss surgery have been associated with bone resorption, potentially jeopardizing total knee arthroplasty (TKA) implant fixation/ingrowth. PURPOSE: This case-control study sought to determine if TKA patients with history of bariatric surgery exhibit altered microanatomy of subchondral bone quality in the tibial plateau compared to controls. MATERIALS AND METHODS: With IRB approval, 41 bone samples were evaluated from 12 former bariatric surgery patients and 10 sex-, age-, weight-, height-, and BMI-matched controls. Patient-Reported Outcomes Measurement Information System (PROMIS) surveys were completed prior to TKA. Tibial plateau osteochondral tissues were recovered during the TKA procedure, and samples from the medial and lateral plateaus were dissected into 1 × 2 cm sections, scanned using microcomputed tomography (µCT), and plastic-embedded for histologic sectioning/staining of undecalcified bone. Paired t tests with Bonferroni correction were performed to assess group differences. RESULTS: Female bariatric surgery patients had reduced osteoid/total area and greater osteoclast number asymmetry than female controls (p < 0.03). No differences were noted in µCT or histologic bone parameters between bariatric and control patients when the sexes were combined. Bariatric patients self-reported worse preoperative PROMIS pain interference and physical function scores than controls (p < 0.04). CONCLUSIONS: Similarities of subchondral bone between former bariatric surgery patients and matched controls indicate OA disease progression dominates the bone landscape in both patient groups.

Bacterial DNA screening to characterize surgical site infection risk in orthopaedic patients.

PURPOSE: To provide an initial characterization of relevant bacterial DNA profiles for patients undergoing closed-fracture fixation or total joint arthroplasties. PATIENTS AND METHODS: Swabs were collected and analyzed using Polymerase Chain Reaction from adult patients undergoing closed-fracture fixation or total shoulder, knee, or hip arthroplasties. RESULTS: Bacterial DNA profiles varied across the different orthopaedic patient populations, and produced uncharacteristic profile shifts with direct relevance to each clinical infection. CONCLUSION: Findings provide a foundational dataset regarding bacterial colonization of relevant anatomic sites that can act as sources of surgical site infections for patients.

TKA is More Durable Than UKA for Morbidly Obese Patients: A Two-Year Minimum Follow-Up Study.

BACKGROUND: Unicompartmental knee arthroplasty (UKA) indications have expanded during the past two decades to include some morbidly obese patients (body mass index (BMI) > 40 kg/m2). Few published studies have compared UKA and total knee arthroplasty (TKA) in this unique patient subgroup with conflicting observations. METHODS: We retrospectively compared 89 mobile bearing UKA (71 patients) and 201 TKA (175 patients) performed at a single institution with a minimum 2-year follow-up (mean 3.4 years). Demographic characteristics were similar for both patient cohorts. A detailed medical record review was performed to assess the frequency of component revision, revision indications, minor secondary procedures (components retained), and infections. RESULTS: UKA was more frequently associated with clinical failure (29.2% vs 2.5%, P < .001) and component revision (15.7% vs 2.5%, P < .001), TKA was more frequently associated with extensor mechanism complications or knee manipulation (5.5% vs 0.0%, P = .02), and there was no difference in the infection rate (3.0% vs 2.2%, P = 1.0). CONCLUSION: Early complications were lower following UKA but were outweighed by higher component revision rates for arthritis progression and implant failure. The study findings suggest that TKA provides a more predictable mid-term outcome for morbidly obese patients considering knee arthroplasty surgery.

Higher Component Malposition Rates with Patient-Specific Cruciate Retaining TKA than Contemporary Posterior Stabilized TKA.

Customized individually manufactured total knee arthroplasty (CIM-TKA) was developed to improve kinematic total knee arthroplasty (TKA) performance. Component placement accuracy may influence the success of CIM-TKA designs. We performed this study to compare radiographic component alignment and revision rates of a cruciate retaining (CR) CIM-TKA and a contemporary posterior stabilized TKA (PS-TKA). After obtaining Institutional Review Board approval, we identified 94 CR CIM-TKAs (76 patients) and 91 PS-TKAs (82 patients) performed between July 1, 2013 and December 31, 2014 with a minimum 2-year follow-up (mean 41.1 months, range 24-59 months). We performed a retrospective electronic medical record review to identify patient demographic characteristics and revision procedures performed. Postoperative plain radiographs were reviewed to assess component alignment including cruciate ligament imbalance, femoral overhang, and femoral notching. Demographic characteristics, component malalignment, and revision surgery rates were assessed using a student's t-test or two-tailed Fisher's exact test, with a p-value < 0.05 designating significance. Technical errors were more commonly identified with CR CIM-TKA (29.8 vs. 9.9%, p < 0.001), including higher rates of tibiofemoral instability (13.8 vs. 1.1%, p < 0.01), femoral notching (12.8 vs. 3.3%, p = 0.03), and patellofemoral malalignment (20.2 vs. 7.7%, p = 0.02). CR CIM-TKA had more frequent coronal plane malposition (26.6 vs. 9.9%, p < 0.01) or sagittal plane reconstruction > 3 degrees outside of an optimized range (20.2 vs. 9.9%, p = 0.06). Aseptic revisions occurred more frequently with the CR CIM-TKA design (9.6 vs. 3.3%, p = 0.13). Demographic characteristics were not significantly different between the treatment groups. CR CIM-TKA may improve kinematic performance for patients undergoing knee replacement surgery. However, our study observations suggest that careful attention to surgical technique is important for optimizing implant survivorship with the CR CIM-TKA design. Additional study is needed to determine whether higher revision rates identified during this study are related to patient selection, surgical technique, or implant design.

Revision Total Knee Arthroplasty in Young Patients: Higher Early Reoperation and Rerevision.

BACKGROUND: Revision total knee arthroplasty (rTKA) rates are increasing in younger patients. Few studies have assessed outcomes of initial aseptic rTKA performed for younger patients compared with traditional-aged patients. METHODS: A detailed medical record review was performed to identify patient demographics, medical comorbidities, surgical rTKA indications, timing from index TKA to rTKA, subsequent reoperation rates, component rerevision rates, and salvage procedures for 147 young patients (158 knees) aged 55 years and younger and for a traditional older cohort of 276 patients (300 knees) between 60 and 75 years. Univariate analysis was performed to assess differences in these primary variables, and a log-rank test was used to estimate 5-year implant survival based on either reoperation or component revision and salvage procedures. RESULTS: Younger TKA patients were more likely to undergo initial aseptic rTKA within 2 years of their primary TKA (52.5% vs 29.0%, P < .001) and were more likely to undergo early reoperation (17.7% vs 9.7%, P = .02) or component rerevision (11.4% vs 6.0%, P < .05) after rTKA. Infection and extensor mechanism complications were more commonly noted in younger patients. Estimated 5-year survival was also lower for both reoperation (59.4% vs 65.7%, P = .02) and component rerevision or salvage (65.8% vs 80.1%, P = .02). CONCLUSION: Early reoperation and component re-rTKA were performed nearly twice as often in younger rTKA than traditional-aged TKA patients. Care should be given to reduce perioperative infection and extensor mechanism failures after rTKA in younger patients.

Characterizing correlations among disease severity measures in osteochondral tissues from osteoarthritic knees.

Osteoarthritis (OA) is a complex disease with biologic, biomechanical, and clinical heterogeneity among patients. Relationships among OA tissue metabolism, histopathology, and extracellular matrix (ECM) composition have not been well characterized. It was hypothesized that moderate (r = .4-.69) to strong (r > .7) correlations exist among these different measures of disease severity in osteochondral tissues from OA knees. Joint surfaces were obtained from patients (n = 6) undergoing total knee arthroplasty. Osteochondral explants (n = 136) were created and cultured for 3 days. Culture media were collected for biomarker analyses, and tissue was assessed for viability, histological scoring, and ECM composition. Correlations among media biomarker concentrations, histological scoring, ECM composition, and viability were determined using a Spearman correlation. GRO-α, IL-6, IL-8, and MCP-1 showed strong positive correlations to each other, and moderate positive correlations to NO, PGE2, and MMP-2. Total MMP activity, MMP-9, and MMP-13 had strong positive correlations to each other, and moderate positive correlations to MMP-1. MMP-2 had a moderate to strong positive correlations to histological scores (total and cartilage structure) and collagen content. MMP-2, IL-6, IL-8, and MCP-1 had moderate negative correlations, and MMP-9 had a moderate positive correlation, to viability. GRO-α, IL-6, IL-8, and MCP-1 had moderate positive correlations to collagen content. MMP-9, MMP-13, and total MMP activity had moderate negative correlations to tissue GAG. The data suggest links among proinflammatory and degradative pathways are present in OA osteochondral tissues. Further characterization of these links have the potential to delineate mechanisms of disease and diagnostic and therapeutic targets for knee OA.

The Past, Present, and Future of Orthopedic Education: Lessons Learned From the COVID-19 Pandemic.

The COVID-19 global pandemic has upended nearly every medical discipline, dramatically impacted patient care and has had far-reaching effects on surgeon education. In many areas of the country, elective orthopedic surgery has completely stopped to ensure that resources are available for the critically ill and to minimize the spread of disease. COVID-19 is forcing many around the world to re-evaluate existing processes and organizations and adapt to carry out business, of which medicine and education are not immune. Most national and international orthopedic conferences, training programs, and workshops have been postponed or canceled, and we are now critically evaluating the delivery of education to our colleagues as well as residents and fellows. This article describes the evolution of orthopedic education and significant paradigm shifts necessary to continue to teach ourselves and the future leaders of our noble profession.

High Failure Rates for Unicompartmental Knee Arthroplasty in Morbidly Obese Patients: A Two-Year Minimum Follow-Up Study.

BACKGROUND: Several recent studies have recommended offering unicompartmental knee arthroplasty (UKA) to all patients regardless of body mass index (BMI). The aim of this investigation was to evaluate the proposition that UKA can indeed be offered to the morbidly-obese and super-obese (morbidly-obese, BMI ≥ 40 kg/m2) without compromising results or survivorship. METHODS: We retrospectively reviewed mobile-bearing medial UKA procedures performed at our facility from January 2012 to May 2015 with a minimum of 2-year follow-up. The study cohort was divided into patients with morbid obesity (BMI ≥ 40 kg/m2) and those without morbid obesity (BMI < 40 kg/m2). A detailed medical record review was performed. Extracted outcome data included the frequency of (1) major revision procedures (components revised), (2) minor secondary procedures (components not revised), (3) infection procedures, and (4) recommendations for revision. RESULTS: We found 152 patients (190 knees) who met criteria for inclusion. Mean follow-up duration was 3.4 years (range: 2.0-6.8 years). Major revision surgery occurred more frequently in the morbid-obesity UKA group (15.7% vs 3.0%, P < .01). Rates of minor secondary surgery and infection were comparable for both groups. Most failures in the morbid-obesity UKA group (85.7%) were due to disease progression involving other compartments or mobile-bearing instability. CONCLUSION: We found the rate of early major revision surgery in morbidly-obese patients undergoing UKA to be over 5-times greater than that of other patients. Failure was predominantly due to disease progression in other compartments or mobile-bearing instability. Further study is warranted and needed before expanding UKA indications to the morbidly-obese population.