Nearly 14-Fold Increased Risk of Manipulation Under Anesthesia After Total Knee Arthroplasty When Previous Contralateral Total Knee Arthroplasty Required Manipulation Under Anesthesia.

BACKGROUND: Stiffness remains a common complication after primary total knee arthroplasty (TKA). Manipulation under anesthesia (MUA) is the gold standard treatment for early postoperative stiffness; however, there remains a paucity of data on the risk of MUA after primary TKA if a prior contralateral TKA required MUA. METHODS: We performed a retrospective review of 3,102 patients who had staged primary TKAs between 2016 and 2021. The mean body mass index was 33 (range, 18 to 59) and the mean age was 67 years (range, 24 to 91). The mean preoperative range of motion for the first TKA was 2 to 104°, and for the contralateral TKA was 1 to 107°. The primary outcomes were MUA following first and second primary TKAs. Multivariable Poisson regressions were used to evaluate associations between risk factors and outcomes. RESULTS: The rate of MUA after the first TKA was 2.6% (n = 83 of 3,102) and 1.3% (n = 40 of 3,102) after the contralateral TKA. After adjustment, there was a nearly 14-fold higher rate of MUA after the second TKA if the patient had an MUA after the first TKA (relative risk, 13.80; 95% CI [confidence interval], 7.14 to 26.66). For the first TKA, increasing age (adjusted risk ratio [ARR], 0.65; 95% CI, 0.50 to 0.83) and increasing body mass index (ARR, 0.65; 95% CI, 0.47 to 0.90) were associated with lower risk for MUA. For the second TKA, increasing age was associated with a lower risk of MUA (ARR, 0.60; 95% CI, 0.45 to 0.80). CONCLUSIONS: For patients undergoing staged bilateral TKA, patients who undergo MUA following the first primary TKA are nearly 14-fold more likely to undergo an MUA following the contralateral primary TKA than those who did not have an MUA after their first TKA.

The John N. Insall Award: Does Melatonin Improve Subjective Sleep Quality After Total Knee Arthroplasty? A Randomized, Placebo-Controlled Trial.

BACKGROUND: Sleep disturbance is a common problem following total knee arthroplasty (TKA). The objective of this study was to determine if exogenous melatonin improves sleep quality following primary TKA. METHODS: A randomized, double-blind, placebo-controlled trial was conducted. A total of 172 patients undergoing unilateral TKA for primary knee osteoarthritis were randomized to receive either 5 mg melatonin (n = 86) or 125 mg vitamin C placebo (n = 86) nightly for 6 weeks. The primary outcome was the Pittsburgh Sleep Quality Index (PSQI) at 6 weeks and 90 days postoperatively. Secondary outcomes included 6-week and 90-day patient-reported outcome measures (PROMs), morphine milligram equivalents prescribed, medication compliance, adverse events, and 90-day readmissions. RESULTS: Mean PSQI scores worsened at 6 weeks before returning to the preoperative baseline at 90 days in both groups. There were no differences in PSQI scores between melatonin and placebo groups at 6 weeks (10.2 ± 4.2 versus 10.5 ± 4.4, P = .66) or 90 days (8.1 ± 4.1 versus 7.5 ± 4.0, P = .43). Melatonin did not improve the Knee Injury and Osteoarthritis Outcome Score for Joint Replacement, Lower Extremity Activity Scale, Visual Analog Scale for pain, or Veterans Rand 12 Physical Component Score or Mental Component Score at 6 weeks or 90 days. Poor sleep quality was associated with worse PROMs at 6 weeks and 90 days on univariate and multivariable analyses, but melatonin did not modify these associations. There were no differences in morphine milligram equivalents prescribed, medication compliances, adverse events, or 90-day readmissions between both groups. CONCLUSIONS: Exogenous melatonin did not improve subjective sleep quality or PROMs at 6 weeks or 90 days following TKA. Poor sleep quality was associated with worse patient-reported function and pain. Our results do not support the routine use of melatonin after TKA.

In Vivo Weight-Bearing Kinematics for Constrained Versus Traditional Bicruciate Stabilized Total Knee Arthroplasty Cohorts Compared to the Normal Knee.

BACKGROUND: Constrained inserts in total knee arthroplasty (TKA) may offer additional stability, but can this insert type allow unrestricted movements or will the extra conformity cause kinematic conflict with the cam-post mechanism in deeper flexion? The objective of this study was to evaluate the weight-bearing kinematics of both traditional and constrained bicruciate stabilized (BCS) TKA inserts to determine if the rollback induced by the cam-post mechanism will work in unison with the constrained polyethylene insert. METHODS: This study used previously published 3-dimensional model fitting techniques to compare weight-bearing flexion and femoro-tibial condylar motion patterns for 20 patients who had a traditional insert, 20 patients who had a constrained insert, and 10 previously published nonimplanted knees, all performing a deep knee bend activity while under fluoroscopic surveillance. RESULTS: The results from this study indicate that subjects having a bicruciate stabilized TKA experienced similar postoperative kinematics for both constrained and unconstrained insert options, comparable to normal knees. CONCLUSIONS: Subjects in this study having either a constrained or traditional insert experienced progressive rollback of both condyles, with the lateral condyle rolling more posterior than the medial condyle, leading to axial rotation. Although less in magnitude, these results were comparable to the normal knee in pattern, indicating that kinematic conflict did not occur for subjects having a constrained insert.

Significantly Worse Fixation of Cemented Patellar Components on Multiacquisition Variable-Resonance Image Combination Magnetic Resonance Imaging Compared to Femoral and Tibial Components: A Cause for Concern?

BACKGROUND: The etiology of anterior knee pain after total knee arthroplasty (TKA) remains unclear. Few studies have examined patellar fixation quality. The purpose of the present study was to evaluate the patellar cement-bone interface after TKA on magnetic resonance imaging (MRI) and to correlate the patella fixation grade with the incidence of anterior knee pain. METHODS: We retrospectively reviewed 279 knees undergoing metal artifact reduction MRI for either anterior or generalized knee pain at least 6 months after cemented, posterior-stabilized TKA with patellar resurfacing with one implant manufacturer. MRI cement-bone interfaces and percent-integration of the patella, femur, and tibia were assessed by a fellowship-trained senior musculoskeletal radiologist. The grade and character of the patella interface were compared to the femur and tibia. Regression analyses were used to determine the association between patella integration with anterior knee pain. RESULTS: There were more patellar components with ≥75% zones of fibrous tissue (50%) compared to the femur (18%) or tibia (5%) (P < .001). There were a greater number of patellar implants with poor cement integration (18%) compared to the femur (1%) or tibia (1%) (P < .001). MRI findings showed more evidence of patellar component loosening (8%) compared to the femur (1%) or tibia (1%) (P < .001). Anterior knee pain was correlated with worse patella cement integration (P = .01), with women predicted to have better integration (P < .001). CONCLUSION: The quality of the patellar cement-bone interface after TKA is worse compared to the femoral or tibial component interface. Poor patellar cement-bone interface may be a source of anterior knee pain after TKA, but further investigation is required.

Comparison of clinical outcomes of VISIONAIRE patient-specific instrumentation with conventional instrumentation in total knee arthroplasty: a systematic literature review and meta-analysis.

INTRODUCTION: Malalignment and resulting complications are major challenges in total knee arthroplasty (TKA) which patient-specific instrumentation (PSI) is proposed to alleviate. Previous PSI meta-analyses of TKA outcomes typically do not differentiate between PSI systems and assess relatively few outcomes, so the value of their findings is limited. VISIONAIRE™ cutting guides (Smith + Nephew Inc., Memphis, TN, USA) is a PSI system based on preoperative magnetic resonance and X-ray imaging. A systematic literature review (SLR) and meta-analysis, focussed specifically on VISIONAIRE, were conducted to assess TKA accuracy, intraoperative outcomes, and postoperative outcomes, compared with conventional instrumentation (CI). MATERIALS AND METHODS: The SLR was performed using PubMed, Embase, and Google Scholar databases to identify relevant studies published until March 2022. Depending on statistical heterogeneity, meta-analyses were performed for outcome measures with fixed effect (I2 < 50%) or random-effects models (I2 ≥ 50%). Dichotomous outcomes were reported as odds ratios and continuous outcomes were reported as mean differences. Descriptive analyses were performed for outcomes not amenable to meta-analysis. RESULTS: Outcomes for VISIONAIRE versus CI were reported in 25 studies. Compared with CI, VISIONAIRE reduced odds of mechanical outliers by 40% (p < 0.0001), with no statistically significant differences in odds of overall coronal, sagittal, or rotational plane component outliers. VISIONAIRE improved surgical efficiency (operating room, turnover, and tourniquet times reduced by 7.3% (p = 0.02), 42% (p = 0.022), and 15.9% (p = 0.01), respectively), lowering the odds of blood transfusion by 53% (p = 0.01) and shortening patients' hospital stays (11.1% reduction; p < 0.0001). There were no significant differences between groups in incidence of postoperative complications and (descriptively analyzed) return-to-function outcomes. CONCLUSION: Options for PSI in TKA differ substantially, and it is important to assess the outcomes of individual systems. The current findings suggest that VISIONAIRE guides can lead to improved alignment accuracy and surgical efficiency compared with CI, without compromising postoperative safety and return-to-function outcomes.

COVID-19 disruptions to elective postoperative care did not adversely affect early complications or patient reported outcomes of primary TKA.

INTRODUCTION: Elective orthopedic care, including in-person office visits and physical therapy (PT), was halted on March 16, 2020, at a large, urban hospital at the onset of the local COVID-19 surge. Post-discharge care was provided predominantly through a virtual format. The purpose of this study was to assess the impact of postoperative care disruptions on early total knee arthroplasty (TKA) outcomes, specifically 90-day complications, 120-day rate of manipulation under anesthesia (MUA) and 1-year patient-reported outcome measures (PROMs). MATERIALS AND METHODS: Institutional records were queried to identify 624 patients who underwent primary, unilateral TKA for osteoarthritis and who were discharged home between 1/1/20 and 3/15/20. These patients were compared to 558 controls discharged between 1/1/19 and 3/15/2019. Cohort demographics and in-hospital characteristics were equivalent apart from inpatient morphine milligram equivalent (MME) consumption. Patient-reported access to PT (p < 0.001) and post-discharge care (p < 0.001) were worse among study patients. Study patients were prescribed fewer post-discharge PT sessions (19.8 vs. 23.5; p < 0.001) and utilized telehealth more frequently (p < 0.001). Mann-Whitney U, T, Fisher's Exact, and chi-squared tests were used to compare outcomes. RESULTS: Ninety-day CMS complications were lower among study patients (3.5% vs. 5.9%; p = 0.05). Rates of MUA were similar between groups. Study patients reported similar PROMs and marginally inferior VR-12 mental and LEAS functional outcomes at 1 year. CONCLUSION: Disruptions to elective orthopedic care in March 2020 seemed to have had no major consequences on clinical outcomes for TKA patients. Our findings question the usefulness of pre-pandemic post-discharge protocols, which may over-emphasize in-person visits and PT.

Posterior Tibial Slope in Computer-Navigated Total Knee Arthroplasty: The Transmalleolar Sagittal Axis Underestimates Slope Compared to Traditional Intramedullary Axis.

BACKGROUND: Tibial slope in total knee arthroplasty (TKA) impacts knee flexion, balance, and ligament strain. Implants were initially designed with tibial slope recommendations based on the intramedullary axis. However, technology-assisted TKA, such as robotics or navigation, determines slope from the ankle-knee axis connecting the center of the transmalleolar line to the proximal exit point of the tibial shaft axis. We sought to quantify the difference in tibial slope between the traditional intramedullary and transmalleolar sagittal tibial axes. METHODS: We retrospectively identified 40 TKAs with preoperative computed tomography scans. We reconstructed the 3-dimensional geometry of the tibia and fibula and determined the intramedullary axis as the best fit cylinder to the tibial shaft. We defined the transmalleolar axis according to accepted industry standards. We measured the angular difference between both axes in the sagittal plane. RESULTS: The transmalleolar axis was radiographically posterior to the intramedullary axis in 39 knees. Utilizing the transmalleolar axis to set posterior tibial slope would reduce the posterior tibial slope by a mean of 1.9° ± 1.3° compared to the intramedullary axis. Furthermore, the posterior slope would be reduced between 0° and 2° in 24 knees (60%), between 2° and 4° in 10 knees (25%), and more than 4° in 5 knees (13%). CONCLUSION: Tibial components implanted with technology assistance referencing the transmalleolar axis to set posterior slope will show an average of 1.9° less posterior slope when measured in sagittal plain radiographs, potentially concerning for knee kinematics.

Modern Internet Search Analytics and Total Joint Arthroplasty: What Are Patients Asking and Reading Online?

BACKGROUND: Patients considering total joint arthroplasty often search for information online regarding surgery; however, little is known about the specific topics that patients search for and the nature of the information provided. Google compiles frequently asked questions associated with a search term using machine learning and natural language processing. Links to individual websites are provided to answer each question. Analysis of this data may help improve understanding of patient concerns and inform more effective counseling. METHODS: Search terms were entered into Google for total hip and total knee arthroplasty. Frequently asked questions and associated websites were extracted to a database using customized software. Questions were categorized by topic; websites were categorized by type. JAMA Benchmark Criteria were used to assess website quality. Pearson's chi-squared and Student's t-tests were performed as appropriate. RESULTS: A total of 620 questions (305 total knee arthroplasties, 315 total hip arthroplasties) were extracted with 602 associated websites. The most popular question topics were Specific Activities (23.5%), Indications/Management (15.6%), and Restrictions (13.4%). Questions related to Pain were more common in the TKA group (23.0% vs 2.5%, P < .001) compared to THA. The most common website types were Academic (31.1%), Commercial (29.2%), and Social Media (17.1%). JAMA scores (0-4) were highest for Government websites (mean 3.92, P = .005). CONCLUSION: The most frequently asked questions on Google related to total joint arthroplasty are related to arthritis management, rehabilitation, and ability to perform specific tasks. A sizable proportion of health information provided originate from non-academic, non-government sources (64.4%), with 17.1% from social media websites.

Natural Language Processing of Patient-Experience Comments After Primary Total Knee Arthroplasty.

BACKGROUND: There is interest in improving patient experience after total knee arthroplasty (TKA) due to recent shifts toward value-based medicine. Patient narratives are a valuable but unexplored source of information. METHODS: Records of 319 patients who had undergone primary TKA between August 2016 and August 2019 were linked with vendor-supplied patient satisfaction data, which included patient comments and the Press Ganey satisfaction survey. Using machine-learning-based natural language processing, 1048 patient comments were analyzed for sentiment and classified into themes. Postoperative outcomes, patient-reported outcome measures, and traditional measures of satisfaction were compared between patients who provided a negative comment vs those who did not (positive, neutral, mixed grouped together). Multivariable regression was used to determine perioperative variables associated with providing a negative comment. RESULTS: Of the 1048 patient comments, 25% were negative, 58% were positive, 8% were mixed, and 9% were neutral. Top 2 themes of negative comments were room condition (25%) and inefficient communication (23%). There were no differences in most of the studied outcomes (eg, peak pain intensity, length of stay, or Knee Injury and Osteoarthritis Outcome Score Junior and pain scores at 6-week follow-up) between the 2 cohorts (P > .05). However, patients who made negative comments were less likely to highly recommend their hospital care to peers (P < .001). Finally, patients who had higher American Society of Anesthesiologists Score and those who received a scopolamine patch were more likely to provide negative comments (P < .05). CONCLUSION: Although the current study showed that patient satisfaction might not be a proxy for traditional objective perioperative outcomes, efforts to improve the nontechnical aspects of medicine are still crucial in providing patient-centered care.

Reduction of Opioids Prescribed Upon Discharge After Total Knee Arthroplasty Significantly Reduces Consumption: A Prospective Study Comparing Two States.

BACKGROUND: Opioids prescribed for acute pain after total knee arthroplasty (TKA) play a contributing role in the number of opioid pills in circulation. At the height of an opioid epidemic in the United States, opioids are increasingly diverted, misused, and abused. Therefore, many states have enacted narcotic regulations in an attempt to curb opioid diversion and misuse. The purpose of this study is to evaluate the effect of stricter state prescribing regulations on opioid consumption following TKA. METHODS: In total, 165 opioid-naive patients undergoing primary unilateral TKA at a single institution with a standardized perioperative pain protocol were reviewed. Seventy-one patients (group 1) resided in a state with strict opioid regulations that limit the initial number of pills dispensed and refills, whereas 92 patients (group 2) resided in another state without quantity and refill regulations. Patient demographics were similar between the 2 groups. Mean age was 64 and mean body mass index was 32 kg/m2. Opioid consumption, quantity, and refill patterns were collected for 6 weeks following surgery. RESULTS: The average oral morphine equivalents consumed during the 6 weeks postsurgery were significantly lower in group 1 at 446.3 ± 266.3 mg (range 10-992) compared to group 2 at 622.6 ± 313.7 mg (range 20-1416) (P < .001). The average oral morphine equivalent corresponds to 60 tablets of 5 mg oxycodone per patient in group 1 vs 84 tablets per patient in group 2. Fifty-nine (83%) patients in group 1 had stopped taking opioids within 6 weeks of surgery compared to 59 (64%) in group 2 (P = .04). CONCLUSION: Based on our results, the institution of state regulations aimed at decreasing the quantity and refills of postoperative opioids led patients to consume less opioids following TKA. Many patients are prescribed more opioids than they require which increases their consumption and can increase the risk for diversion, addiction, and misuse. LEVEL OF EVIDENCE: Level III; retrospective comparative cohort study.

Immersive technologies for total knee arthroplasty surgical education.

The need to adapt surgical curricula to meet the demands of an increasingly restrictive training environment is rising. Modern constraints of surgical trainees including work-hour restrictions and concerns surrounding patient safety have created an opportunity to supplement traditional teaching methods with developing immersive technologies including virtual and augmented reality. Virtual reality (VR) and augmented reality (AR) have been preliminarily investigated as it relates to total joint arthroplasty. The purpose of this article is to discuss VR and AR as it applies to modern total knee replacement (TKR) surgical education.

Reasons and Risk Factors for 30-Day Readmission After Outpatient Total Knee Arthroplasty: A Review of 3015 Cases.

BACKGROUND: A higher volume of primary total knee arthroplasty (TKA) is starting to be performed in the outpatient setting. However, data on appropriate patient selection in the current literature are scarce. METHODS: Patients who underwent primary TKA were identified in the 2012-2017 National Surgical Quality Improvement Program database. Outpatient procedure was defined as having a hospital length of stay of 0 days. The primary outcome was a readmission within the 30-day postoperative period. Reasons for and timing of readmission were identified. Risk factors for and effect of overnight hospital stay on 30-day readmission were evaluated. RESULTS: A total of 3015 outpatient TKA patients were identified. The incidence of 30-day readmission was 2.59% (95% confidence interval [CI] 2.02-3.15). The majority of readmissions were nonsurgical site related (64%), which included thromboembolic and gastrointestinal complications. Risk factors for 30-day readmission include dependent functional status prior to surgery (relative risk [RR] 6.4, 95% CI 1.91-21.67, P = .003), hypertension (RR 2.5, 95% CI 1.47-4.25, P = .001), chronic obstructive pulmonary disease (RR 2.4, 95% CI 1.01-5.62, P = .047), and operative time ≥91 minutes (≥70th percentile) (RR 1.9, 95% CI 1.17-2.98, P = .008). For patients who had some of these risk factors, their rate of 30-day readmission was significantly reduced if they had stayed at least 1 night at the hospital. CONCLUSION: Overall, the rate of 30-day readmission after outpatient TKA was low. Patients who are at high risk for 30-day readmission after outpatient TKA include those with dependent functional status, hypertension, chronic obstructive pulmonary disease, and prolonged operative time. These patients had reduced readmissions after overnight admission and seem to benefit from an inpatient hospital stay.

Can We Avoid Implant-selection Errors in Total Joint Arthroplasty?

BACKGROUND: Implant selection in the operating room is a manual process. This manual process combined with complex compatibility rules and inconsistent implant labeling may lead to implant-selection errors. These might be reduced using an automated process; however, little is known about the efficacy of available automated error-reduction systems in the operating room. QUESTIONS/PURPOSES: (1) How often do implant-selection errors occur at a high-volume institution? (2) What types of implant-selection errors are most common? METHODS: We retrospectively evaluated our implant log database of 22,847 primary THAs and TKAs to identify selection errors. There were 10,689 THAs and 12,167 TKAs included during the study period from 2012 to 2017; there were no exclusions and we had no missing data in this study. The system provided an output of errors identified, and these errors were then manually confirmed by reviewing implant logs for each case found in the medical records. Only those errors that were identified by the system were manually confirmed. During this time period all errors for all procedures were captured and presented as a proportion. Errors identified by the software were manually confirmed. We then categorized each mismatch to further delineate the nature of these events. RESULTS: One hundred sixty-nine errors were identified by the software system just before implantation, representing 0.74 of the 22,847 procedures performed. In 15 procedures, the wrong side was selected. Twenty-five procedures had a femoral head selected that did not match the acetabular liner. In one procedure, the femoral head taper differed from the femoral stem taper. There were 46 procedures in which there was a size mismatch between the acetabular shell and the liner. The most common error in TKA that occurred in 46 procedures was a mismatch between the tibia polyethylene insert and the tibial tray. There were 13 procedures in which the tibial insert was not matched to the femoral component according to the manufacturer's guidelines. Selection errors were identified before implantation in all procedures. CONCLUSIONS: Despite an automated verification process, 0.74% of the arthroplasties performed had an implant-selection error that was identified by the software verification. The prevalence of incorrect/mismatched hip and knee prostheses is unknown but almost certainly underreported. Future studies should investigate the prevalence of these errors in a multicenter evaluation with varying volumes across the involved sites. Based on our results, institutions and management should consider an automated verification process rather than a manual process to help decrease implant-selection errors in the operating room. LEVEL OF EVIDENCE: Level IV, therapeutic study.

Satisfaction Rates and Quality of Life Changes Following Total Knee Arthroplasty in Age-Differentiated Cohorts.

BACKGROUND: Comparisons of satisfaction rates following total knee arthroplasty (TKA) among large, age-differentiated, rigorously matched cohorts are lacking. Therefore, we compared satisfaction rates following TKA in large, age-differentiated, propensity score-matched cohorts. METHODS: We identified primary TKAs performed for non-inflammatory arthritis in patients of ages 18-55 or 65-75, yielding 529 younger and 2001 older patients. Patient-reported outcomes were recorded pre-operatively and 2 years post-operatively. 1:1 propensity score matching between groups yielded 529 patient pairs. Matching was based on gender, body mass index, American Society of Anesthesiologists grade, Charlson Comorbidity Index, and Short Form 12 Mental Health Component score. Outcomes were compared between matched groups using t-test and Wilcoxon rank-sum test. RESULTS: Satisfaction with knee surgery was 86% among younger patients and 91% among older patients. Distribution of satisfaction responses was shifted toward greater satisfaction in older patients (P < .001). Overall quality of life (QOL) improvement was 91% among younger patients and 96% among older patients. Pre-operative and post-operative knee-related QOL was better among older patients (P < .0001). Post-operative global health-related QOL was equivalent between groups based on Short Form 12 Physical Component Score and Mental Health Component score (P = .6646 and P = .5705, respectively) and QOL improvement questionnaires (P = .181). Younger patients reported greater knee-related dysfunction and higher activity levels pre-operatively and post-operatively (P ≤ .0002). CONCLUSION: Satisfaction with knee surgery was over 85% regardless of age. Younger patients perceived more knee-related dysfunction and dissatisfaction after surgery despite higher levels of self-reported activity pre-operatively and post-operatively.

Robotic-Assisted Unicompartmental Knee Arthroplasty: State-of-the Art and Review of the Literature.

BACKGROUND: Unicompartmental knee arthroplasty is a successful treatment for unicompartmental knee osteoarthritis that has lower complication rates, faster recovery, and a more natural feeling knee compared to total knee arthroplasty. However, long-term survival has been a persistent concern. As more surgeon-controlled variables have been linked to survival, interest in robotic-assisted surgery has continued to grow. METHODS: A review and synthesis of the literature on the subject of robotic-assisted unicompartmental knee arthroplasty was performed. RESULTS: We present the driving factors behind the development of robotic-assisted techniques in unicompartmental knee arthroplasty and the current state-of-the art. The ability of surgeons to achieve intraoperative targets with robotic assistance and the outcomes of robotic-assisted surgery are also described. CONCLUSION: Robotic-assisted surgery has become increasingly popular in unicompartmental knee arthroplasty, as it allows surgeons to more accurately and reproducibly plan and achieve operative targets during surgery. Cost remains a concern, and it remains to be seen whether robotic-assisted surgery will improve long-term survivorship after unicompartmental knee arthroplasty.

Discharge to Inpatient Rehab Does Not Result in Improved Functional Outcomes Following Primary Total Knee Arthroplasty.

BACKGROUND: Monitored rehabilitation has long been considered an essential part of the recovery process in total knee arthroplasty (TKA). However, the optimal setting for rehabilitation remains uncertain. We sought to determine whether inpatient rehabilitation settings result in improved functional and patient-reported outcomes after primary TKA. METHODS: All patients undergoing primary TKA from May 2007 to February 2011 were identified from our institutional total joint registry. Propensity score matching was then performed, resulting in a final cohort of 1213 matched pairs for discharge destination to either home or a rehabilitation facility (inpatient rehab or skilled nursing facility). Length of stay, need for manipulation, 6-month complications, and 2-year Western Ontario and McMaster Universities Osteoarthritis Index, Lower Extremity Activity Scale, 12-item Short Form Health Survey, and Hospital for Special Surgery knee expectations surveys were compared. RESULTS: Patients discharged to a rehab facility were noted to have a shorter hospital length of stay (5.0 vs 5.4 days). Patients discharged to inpatient rehabilitation reported more fractures at 6 months postoperatively. However, no differences in manipulation rates, 2-year outcome scores, or changes in outcome scores were found between the 2 groups. CONCLUSION: Inpatient rehabilitation settings did not result in lower complications at 6 months or improved functional or patient-reported outcomes at 2 years compared to discharge directly to home when patients are propensity matched for age, living situation, comorbidities, baseline functional status, and insurance status. This finding has important cost implications and calls into question whether the healthcare system should allow otherwise healthy patients to use inpatient rehabilitation services postoperatively after primary TKA.

Does Achieving High Flexion Increase Polyethylene Damage in Posterior-Stabilized Knees? A Retrieval Study.

BACKGROUND: Increased range of motion to higher degrees of flexion following total knee arthroplasty has been postulated to increase implant damage and revision rates, even in designs modified to accommodate high flexion. METHODS: We examined posterior-stabilized and high-flexion retrieved tibial inserts to look for differences in polyethylene surface damage with light microscopy and 3D deviation with laser scanning between inserts from patients who achieved a high degree of flexion (≥120° postoperatively) and inserts from patients who did not reach a high degree of flexion. RESULTS: No differences were found in damage scores on the articular and backside surfaces, except for abrasion in the posterior articular regions, or in 3D deviations between patients who reached a high degree of flexion and patients who did not. These results were independent of the reason for revision. CONCLUSION: In our series, reaching a high degree of flexion did not influence surface damage or 3D deviation of the polyethylene inserts.

Oxidized zirconium versus cobalt-chromium in TKA: profilometry of retrieved femoral components.

BACKGROUND: Oxidized zirconium (OxZr) was introduced as an alternative bearing for femoral components in total knee arthroplasty (TKA) in an attempt to reduce wear compared with conventional cobalt-chromium (CoCr) alloys. QUESTIONS/PURPOSES: The aim of this study was to compare matched pairs of retrieved OxZr and CoCr components using surface profilometry; specifically, we sought to compare the surface roughness of (1) retrieved OxZr TKA components with retrieved CoCr components; (2) the medial versus the lateral femoral condyles of retrieved components; and (3) unimplanted OxZr TKA components with unimplanted CoCr components. METHODS: Ten retrieved posterior-stabilized Genesis II TKA with OxZr femoral components were identified and matched to retrieved CoCr femoral components by duration of implantation, patient age, and body mass index. A noncontact white light interferometer was used to evaluate surface roughness. One pristine, unimplanted component of each design was analyzed as a control. RESULTS: The retrieved components showed significantly (p < 0.0001) lower roughness for the OxZr components than the CoCr components. CoCr retrievals showed a significantly greater average surface roughness on the medial condyle. No difference was found between the condyles of the OxZr components. The pristine CoCr implant had a significantly lower surface roughness than the pristine OxZr component. CONCLUSIONS: CoCr roughens significantly more in situ compared with OxZr components. CLINICAL RELEVANCE: Bearing surfaces are typically damaged in vivo. The extent of damage is variable between patients and implants; however, rougher surfaces should be associated with more wear. Whether the differences observed in our study prove meaningful requires long-term clinical data.

Polished trays reduce backside wear independent of post location in posterior-stabilized TKAs.

BACKGROUND: Backside damage of the polyethylene in TKA is a potential source of debris. The location of the tibial post in posterior-stabilized implants may influence micromotion, and thus affect backside damage, as may surface roughness. QUESTIONS: We used implant retrieval analysis to (1) examine if there were differences in backside damage among three modern posterior-stabilized implants attributable to variable surface roughness; (2) determine if the location of damage on the tibial post affected the pattern of backside damage; and (3) determine if demographics influenced backside damage. METHODS: We identified 403 posterior-stabilized tibial retrieved inserts (147 NexGen(®), 152 Optetrak(®), 104 Genesis(®) II). The damage on the surfaces of the tibial posts was previously graded. The backside of the inserts (divided into quadrants) were scored for evidence of damage. The total quadrant damage was compared for each implant group, the relationship between post face damage and location of damage on the backside was determined for each implant group, and total backside damage was compared among the three implant groups. RESULTS: No correlation was found between the location of damage on the post and location of damage on the backside of the implant for any of the three groups. The Genesis(®) II polyethylene implants, which articulate with a highly polished tibial tray, showed a significantly lower total backside damage score (p < 0.01) when compared with the other two implant groups. The Genesis(®) II and Optetrak(®) showed significantly more damage in the posterior quadrants of the implants (p < 0.01) when compared with the anterior quadrants. A linear regression analysis revealed that lower tibial tray surface roughness was correlated with decreased damage. CONCLUSIONS: An implant design with a highly polished tibial tray was associated with decreased backside damage. However, tibial post design and location did not influence the location of backside damage. CLINICAL RELEVANCE: Our study showed that a highly polished tibial tray was associated with decreased damage to the backside of polyethylene inserts independent of post design and location. These findings should be taken into consideration when new generations of implants are designed.