Shared Decision-Making Is Associated with Better Outcomes in Patients with Knee But Not Hip Osteoarthritis: The DECIDE-OA Randomized Study.

BACKGROUND: Current guidelines recommend shared surgical decision-making, yet it is unclear whether shared decision-making improves health outcomes in patients who are considering knee and hip replacement. The purpose of the present study was to examine whether patients who made high-quality, informed, patient-centered (IPC) decisions had better health outcomes, higher satisfaction, and less decision regret compared with those who made lower-quality decisions. METHODS: A multisite, randomized study of 2 decision aids for patients with hip and knee osteoarthritis was utilized to collect data on decision-making and health outcomes at 2 time points: shortly after the initial surgical evaluation and about 6 months after treatment. We calculated the percentage of patients who made an IPC decision and examined the a priori hypotheses that IPC decisions would be associated with better health outcomes, satisfaction, and less regret at 6 months. Linear and logistic regression models were utilized to examine the relationships. RESULTS: The analytic sample included 854 patients with a mean age of 65 years (standard deviation, 9 years), of whom 58% were female, 93% were White non-Hispanic, 67% had knee (compared with hip) osteoarthritis, and 62% underwent operative treatment within 6 months of the initial evaluation. The majority of patients (68%) made IPC decisions. The IPC group had significantly larger gains in quality of life (mean difference in EuroQol-5 Dimension, 0.04; 95% confidence interval [CI], 0.02 to 0.07; p < 0.001) compared with the non-IPC group. For knee patients, the IPC group also had significantly better Knee injury and Osteoarthritis Outcome Scores (mean difference, 4.9; 95% CI, 1.5 to 8.3; p = 0.004), higher satisfaction (adjusted odds ratio [aOR], 1.7; 95% CI, 1.2 to 2.3; p = 0.003), much better pain relief (aOR, 2.1; 95% CI, 1.3 to 3.5; p = 0.002), and were more likely to have no decision regret (aOR, 2.3; 95% CI, 1.3 to 4.1; p = 0.003). For hip patients, IPC decisions were not associated with better Harris hip scores or satisfaction and were associated with more regret. CONCLUSIONS: Higher-quality decisions predicted small improvements in health outcomes, as well as greater satisfaction and less regret for patients with knee osteoarthritis, but not for patients with hip osteoarthritis. LEVEL OF EVIDENCE: Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.

Variation in perioperative opioid use after total joint arthroplasty.

OBJECTIVE: We studied variation in perioperative opioid use after total joint arthroplasty with respect to patient and procedure characteristics in order to inform initiatives to optimize pain relief. METHODS: We recorded perioperative opioid consumption for a cohort of total joint arthroplasty patients to identify factors underlying variation in perioperative opioid use. RESULTS: Younger patient age, tobacco use, greater symptoms of depression, private insurance, and knee arthroplasty were associated with increased opioid consumption. CONCLUSIONS: Awareness of the patient characteristics associated with increased perioperative opioid use can help inform implementation of targeted strategies for safe, optimal pain relief and satisfaction.

Validation of an electronic coding algorithm to identify the primary indication of orthopedic surgeries from administrative data.

BACKGROUND: Determining the primary indication of a surgical procedure can be useful in identifying patients undergoing elective surgery where shared decision-making is recommended. The purpose of this study was to develop and validate an algorithm to identify patients receiving the following combinations of surgical procedure and primary indication as part of a study to promote shared decision-making: (1) knee arthroplasty to treat knee osteoarthritis (KOA); (2) hip arthroplasty to treat hip osteoarthritis (HOA); (3) spinal surgery to treat lumbar spinal stenosis (SpS); and (4) spinal surgery to treat lumbar herniated disc (HD). METHODS: Consecutive surgical procedures performed by participating spine, hip, and knee surgeons at four sites within an integrated care network were included. Study staff reviewed electronic medical records to ascertain a "gold standard" determination of the procedure and primary indication status. Electronic algorithms consisting of ICD-10 and CPT codes for each combination of procedure and indication were then applied to records for each case. The primary measures of validity for the algorithms were the sensitivity and specificity relative to the gold standard review. RESULTS: Participating surgeons performed 790 procedures included in this study. The sensitivity of the algorithms in determining whether a surgical case represented one of the combinations of procedure and primary indication ranged from 0.70 (HD) to 0.92 (KOA). The specificity ranged from 0.94 (SpS) to 0.99 (HOA, KOA). CONCLUSION: The electronic algorithm was able to identify all four procedure/primary indication combinations of interest with high specificity. Additionally, the sensitivity for the KOA cases was reasonably high. For HOA and the spine conditions, additional work is needed to improve the sensitivity of the algorithm to identify the primary indication for each case.

Decision Support Strategies for Hip and Knee Osteoarthritis: Less Is More: A Randomized Comparative Effectiveness Trial (DECIDE-OA Study).

BACKGROUND: As guidelines and payers increasingly recommend use of patient decision aids (DAs), evidence about the comparative effectiveness of available DAs is critical for organizations interested in implementing them. The primary purpose of this study was to compare 2 DAs with regard to their ability to help patients become informed and receive their preferred treatment (that is, make an informed patient-centered decision), shared decision-making, surgical rates, and surgeon satisfaction. METHODS: We performed a multisite factorial randomized trial enrolling patients with hip or knee osteoarthritis. Patients were randomly assigned to use a long, detailed DA (long DA) or short, interactive DA (short DA). Eight surgeons were randomly assigned to receive a patient preference report detailing the patient's goals and treatment preferences or to administer usual care. RESULTS: We distributed 1,636 pre-visit surveys, 1,220 of which were returned (75% response rate), and 1,124 post-visit surveys, 967 of which were returned (86% response rate). The patients in the sample had a mean age (and standard deviation) of 65 ± 10 years, 57% were female, 89% were white non-Hispanic, and 67% had knee osteoarthritis. The majority (67.2%) made informed patient-centered decisions, and the rate did not vary significantly between the DA groups (p = 0.97) or between the surgeon groups (p = 0.23). Knowledge scores were higher for the short-DA group (mean difference = 9%; p < 0.001). More than half of the sample (60.5%) had surgery within 6 months after the visit, and rates did not differ significantly by DA or surgeon group. Overall, the surgeons were highly satisfied and reported that the majority (88.7%) of the visits were of normal duration or shorter. CONCLUSIONS: The DECIDE-OA study is, to our knowledge, the first randomized comparative effectiveness study of 2 orthopaedic DAs. The short DA outperformed the long DA with regard to knowledge scores and was comparable with respect to other outcomes. The surgeons reported high satisfaction and normal visit duration with both DAs. CLINICAL RELEVANCE: Surgeons need to ensure that patients with osteoarthritis are well-informed and have a clear preference regarding whether to undergo hip or knee replacement surgery. The DAs used in this study may help surgeons involve patients in elective surgery decisions and meet the requirements of informed consent.

Early post-operative opioid consumption: A comparison between medial unicompartmental, patellofemoral, and total knee arthroplasty.

BACKGROUND: While there is emerging literature describing the use of narcotics for post-operative pain control following TKA, little data is available regarding narcotic use in partial knee replacements. The aim of this study is to compare the early post-operative narcotic requirements after medial compartmental arthroplasty (UKA) and patellofemoral arthroplasty (PFA) with that of TKA. METHODS: In this retrospective chart review, we identified 37 patients who underwent PFA and 71 patients who underwent UKA. We identified a cohort of TKA patients who were matched to the unicompartmental group based on sex and age (n = 108). The primary outcome measure was self-reported use of opioids for pain management at the first post-operative clinic visit. Opioid use between groups was compared using Chi-square analysis. RESULTS: The PFA group was younger (p < 0.001) and consisted of more females (p < 0.001) than the UKA group. The UKA cohort had more non-smoking patients (p = 0.044) compared to the PFA cohort. Self-reported opioid use at the first post-operative visit differed between the three groups of patients (p < 0.001). A greater proportion of both PFA (38% vs. 11%; p < 0.001) and TKA (41% vs. 11%; p = 0.01) patients reported opioid use when compared to UKA patients. No differences in opioid use existed between TKA and PFA groups (p = 0.61). CONCLUSION: The prevalence of PFA patients who report opioid use at the first post-operative visit is similar to that for patients following TKA, suggesting that pain management protocols for this specific subset of partial knee arthroplasty patients should be structured similar to TKA patients and separate from UKA patients.

Protocol for a randomised trial evaluating the comparative effectiveness of strategies to promote shared decision making for hip and knee osteoarthritis (DECIDE-OA study).

INTRODUCTION: There are several different interventions available to promote shared decision making (SDM); however, little is known about the comparative effectiveness of different approaches. OBJECTIVE: To examine the impact of patient-directed and physician-directed decision support strategies on the quality of treatment decisions for hip and knee osteoarthritis (OA). TRIAL DESIGN: A 2×2 factorial randomised controlled trial. SETTING: One academic medical centre, one community hospital and one orthopaedic specialty hospital. PARTICIPANTS AND INTERVENTIONS: The enrolment targets were 8 surgeons and 1120 patients diagnosed with hip or knee OA. Patients were randomly assigned to receive one of two different decision aids (DAs) stratified by site. The DAs varied in length, content and the level of detail regarding treatment options. Both DAs were available by paper or online.Surgeons were randomly assigned to receive a report detailing patients' goals and treatment preferences at the time of the visit or not. Eligible patients received their assigned DA before their visit and completed three surveys: before the visit (timepoint (T)1), 1-week postvisit (T2) and 6 months from either the visit date or surgery date for patients who underwent surgery (T3). Study staff and participating surgeons were not blinded, but the statistician conducting the analyses was blinded to the arms. MAIN OUTCOME MEASURE AND ANALYSIS: The primary study outcome was decision quality, the percentage of patients who were well informed and received their preferred treatment. Secondary outcomes included involvement in decision making, surgical rates, health outcomes, decision regret and satisfaction. A logistic regression model with the generalised estimating equations approach was used to compare rates of decision quality between the groups and account for the clustering of patients within providers. ETHICS AND DISSEMINATION: Ethics approval was obtained through the institutional review board at the main site. The findings will be published in peer-reviewed journals. TRIAL REGISTRATION NUMBER: NCT02729831; Pre-results.

The Impact of Medical Comorbidities on Primary Total Knee Arthroplasty Reimbursements.

Medical comorbidities have been shown to cause an increase in peri-and postoperative complications following total knee arthroplasty (TKA). However, the increase in cost associated with these complications has yet to be determined. Factors that influence cost have been of great interest particularly after the initiation of bundled payment initiatives. In this study, we present and quantify the influence of common medical comorbidities on the cost of care in patients undergoing primary TKA. A retrospective level of evidence III study was performed using the PearlDiver supercomputer to identify patients who underwent primary TKA between 2007 and 2015. Patients were stratified by medical comorbidities and compared using analysis of variance for reimbursements for the day of surgery and over 90 days postoperatively. A cohort of 137,073 US patients was identified as having undergone primary TKA between 2007 and 2015. The mean entire episode-of-care reimbursement was $23,701 (range: $21,294-26,299; standard deviation [SD] $2,611). The highest reimbursements were seen in patients with chronic obstructive pulmonary disease (mean $26,299; SD $3,030), hepatitis C (mean $25,662; SD $2,766), morbid obesity (mean $25,450; SD $2,154), chronic kidney disease (mean $25,131, $3,361), and cirrhosis (mean $24,890; SD $2,547). Medical comorbidities significantly impact reimbursements, and therefore cost, after primary TKA. Comprehensive preoperative optimization for patients with medical comorbidities undergoing TKA is highly recommended and may reduce perioperative complications, improve patient outcome, and ultimately reduce cost.

Cadaver-Specific Models for Finite-Element Analysis of Iliopsoas Impingement in Dual-Mobility Hip Implants.

BACKGROUND: Joint dislocation is a major cause of failure in total hip arthroplasty. Dual-mobility implants provide a femoral head diameter that can match the native hip size for greater stability against dislocation. However, such large heads are prone to impingement against surrounding soft tissues. To address this concern, the concept of an anatomically contoured dual-mobility implant was evaluated using cadaver-specific finite-element analysis (FEA). METHODS: The stiffness of 10 iliopsoas tendons was measured and also 3D bone models, contact pressure, and iliopsoas tendon stress were evaluated for 2 implant designs according to a previous cadaveric experiment. The iliopsoas interaction with an anatomically contoured and conventional dual-mobility implant was analyzed throughout hip flexion. RESULTS: The tensile test of cadaveric iliopsoas tendons revealed an average linear stiffness of 339.4 N/mm, which was used as an input for the FEA. Tendon-liner contact pressure and tendon von Mises stress decreased with increasing hip flexion for both implants. Average contact pressure and von Mises stresses were lower in the anatomically contoured design compared with the conventional implant across all specimens and hip flexion angles. CONCLUSIONS: This study was built upon a previous cadaver study showing reduced tenting of the iliopsoas tendon for an anatomically contoured design compared with a conventional dual-mobility implant. The present cadaver-specific FEA study found reduced tendon-liner contact pressure and tendon stresses with contoured dual-mobility liners. Anatomical contoured design may be a solution to avoid anterior soft-tissue impingement when using hip prostheses with large femoral heads.

Increasing the use of patient decision aids in orthopaedic care: results of a quality improvement project.

OBJECTIVE: To integrate patient decision aid (DA) delivery to promote shared decision-making and provide more patient-centred care within an orthopaedic surgery department for treatment of hip and knee osteoarthritis, lumbar herniated disc and lumbar spinal stenosis. METHODS: Different strategies were used across three distinct phases to promote DA delivery. First, we used a quality improvement bonus to generate awareness and interest in the DAs among specialists. Second, we adapted the electronic referral management system to enable DA orders at referral to a specialist. Third, we engaged clinic staff and specialists to design workflows that promoted DA delivery. We tracked the number of patients who received a DA, who ordered the DA, and collected usage data from a subset of patients. Our target was to reach 60% of patients with DAs. RESULTS: In phase 1, 28% (43/155) of spine patients and 37% (114/308) of hip/knee patients received a DA. In phase 2, 54% (64/118) of spine referrals and 58% (189/324) of hip/knee referrals included a request to send a patient a DA. In phase 3, 56% (90/162) of spine patients and 69% (213/307) of hip/knee patients received a DA, significantly more than in phase 1 (P<0.0001). In phase 3, both more DAs were ordered by clinic staff compared with specialists (56% phase 3 vs 34% phase 1, P<0.001) and sent before the visit (74% phase 3 vs 17% phase 1, P<0.001). Patients were more likely to report reviewing the DA when delivered before the visit (63% before vs 50% after, P=0.005). CONCLUSION: DA implementation into clinic workflow is possible and facilitated by engagement of the entire care team and the support of health information technology.

Intravenous vs Oral Acetaminophen as an Adjunct to Multimodal Analgesia After Total Knee Arthroplasty: A Prospective, Randomized, Double-Blind Clinical Trial.

BACKGROUND: The efficacy of intravenous (IV) acetaminophen compared with its oral formulation for postoperative analgesia is unknown. We hypothesized that the addition of acetaminophen to a multimodal analgesia regimen would provide improved pain management in patients after total knee arthroplasty (TKA) and that the effect of acetaminophen would be variable based on the route of delivery. METHODS: The study was a single-center, randomized, double-blinded, placebo-controlled clinical trial on the efficacy of IV vs oral acetaminophen in patients undergoing unilateral TKA. One hundred seventy-four subjects were randomized to one of the 3 groups: IV acetaminophen group (IV group, n = 57) received 1 g IV acetaminophen and oral placebo before postanesthesia care unit (PACU) admission; oral acetaminophen group (PO group, n = 58) received 1 g oral acetaminophen and volume-matched IV normal saline; placebo group (Placebo group, n = 59) received oral placebo and volume-matched IV normal saline. Pain scores were obtained every 15 minutes during PACU stay. Average pain scores, maximum pain score, and pain scores before physical therapy were compared among the 3 groups. Secondary outcomes included total opiate consumption, time to PACU discharge, time to rescue analgesia, and time to breakthrough pain. RESULTS: The average PACU pain score was similar in the IV group (0.56 ± 0.99 [mean ± standard deviation]) compared with the PO group (0.67 ± 1.20; P = .84) and Placebo group (0.58 ± 0.99; P = .71). Total opiate consumption at 6 hours (0.47 mg hydromorphone equivalents ± 0.56 vs 0.54 ± 0.53 vs 0.54 ± 0.61; P = .69) and at 24 hours (1.25 ± 1.30 vs 1.49 ± 1.34 vs 1.36 ± 1.31; P = .46) were also similar between the IV, PO, and Placebo groups. No significant differences were found between all groups for any other outcome. CONCLUSION: Neither IV nor oral acetaminophen provides additional analgesia in the immediate postoperative period when administered as an adjunct to multimodal analgesia in patients undergoing TKA in the setting of a spinal anesthetic.

Multiple Hip Intra-Articular Steroid Injections Increase Risk of Periprosthetic Joint Infection Compared With Single Injections.

BACKGROUND: Patients with hip osteoarthritis often temporize their symptoms with multiple intra-articular steroid hip injections (IASHIs) before undergoing total hip arthroplasty (THA). Although there is recent evidence to suggest that IASHI can lead to an increased risk of future periprosthetic joint infection (PJI), the potential increase in risk of PJI after multiple IASHIs compared with single IASHI remains largely unknown. The aim of the study was to evaluate whether multiple IASHIs are associated with increased risk of PJI compared with single IASHI in THA patients. METHODS: We evaluated 2 cohorts of patients consisting of 106 patients who received 2 or more IASHI in the year before THA and a matched group of 350 patients who received one IASHI in the 12 months before THA. RESULTS: The single and multiply-injected patient cohorts had an infection rate of 2.0% and 6.6% (7/350 and 7/106), respectively (P = .04, odds ratio 3.30) and average follow-up of 28.9 and 24.2 months. The 2 cohorts did not differ with regard to age, gender, American Society of Anesthesiologist score, presence of diabetes mellitus, or body mass index. CONCLUSION: In comparison with patients with single IASHI, multiple IASHIs are associated with an increased risk of PJI significantly higher than the elevated risk reported with single injection before THA. The present study findings would be clinically useful in counseling patients who are considering temporizing their symptoms with multiple IASHIs before undergoing THA.

Unsuspected Malignancies in Routine Femoral Head Histopathologic Examination During Primary Total Hip Arthroplasty: Cost-Effectiveness Analysis.

BACKGROUND: Routine femoral head histopathology during primary total hip arthroplasty (THA) has been recently reported as a potentially useful screening tool for bone- and bone marrow-associated malignancies. However, cost-effectiveness of routine histopathology during THA remains unclear due to low prevalence of significant medical findings which alter patient management. The aim of this study was to evaluate the cost-effectiveness of routine histopathology in diagnosing unsuspected malignancy in patients undergoing primary THA. METHODS: From 1993 to 2011, we retrospectively analyzed routine histopathologic findings of 3200 femoral head specimens from 2725 patients that underwent primary THA. Preoperative and postoperative diagnoses were classified into concordant (clinical diagnosis concurred with pathologic diagnosis), discrepant (differing diagnosis with no resultant impact on patient management), and discordant (differing diagnosis with subsequent change in patient management). Cost-effectiveness analysis was performed using the incremental cost-utility ratio. RESULTS: A total of 3055 of 3200 pathologic samples were concordant with the preoperative diagnosis (95.4%), 140 of 3200 were discrepant (4.4%), and 5 of 3200 were discordant (0.2%). Routine histopathology revealed 1 unsuspected malignancy out of 640 (5 of 3200) femoral heads. The total cost of histopathologic screening was $614,664.80. The average cost to identify a discrepant case was $4390.46, and the cost to identify a discordant case was $122,932.96. The incremental cost-utility ratio was $49,569.74 per quality-adjusted life year (QALY) gained. CONCLUSION: Our study indicates routine femoral head histopathology may be cost-effective in diagnosing unsuspected malignancy at $49,569.74/QALY gained (less than World Health Organization recommended threshold $159,000/QALY gained), providing useful clinical information for surgeons considering the value of routine femoral head histopathology in patients undergoing THA.

Asymptomatic Pseudotumors in Patients with Taper Corrosion of a Dual-Taper Modular Femoral Stem: MARS-MRI and Metal Ion Study.

BACKGROUND: Modularity in total hip arthroplasty facilitates intraoperative restoration of patient anatomy. Although dual-taper modular total hip arthroplasty offers potential advantages for optimizing the hip center of rotation, it has been associated with modular taper corrosion. This corrosion has led to adverse local tissue reactions (pseudotumors) at the neck-stem junction and elevated metal-ion levels. However, the occurrence of taper-corrosion-related pseudotumors in patients who remain asymptomatic following total hip arthroplasty with a dual-taper modular femoral stem remains largely unknown. The aims of this study were (1) to determine the prevalence of asymptomatic pseudotumors by utilizing metal artifact reduction sequence magnetic resonance imaging (MARS-MRI) and (2) compare serum metal-ion levels between symptomatic and asymptomatic patients with a dual-taper modular stem total hip replacement. METHODS: We performed a retrospective cross-sectional study of 97 consecutive patients who had been treated with a dual-taper modular femoral stem total hip arthroplasty. Eighty-three patients were stratified into symptomatic and asymptomatic groups and evaluated with MARS-MRI, measurement of serum metal-ion levels, and the University of California at Los Angeles (UCLA) functional hip score. RESULTS: The prevalence of pseudotumors as determined with MARS-MRI was 15% in our asymptomatic patients and 36% in the overall cohort. The median serum cobalt level and cobalt/chromium ratio were significantly higher in patients with a pseudotumor than in those without a pseudotumor (8.0 versus 2.0 µg/L [p = 0.004] and 10.3 versus 2.4 µg/L [p = 0.012], respectively). However, there was no significant difference in the serum cobalt level or cobalt/chromium ratio between symptomatic patients with a pseudotumor and asymptomatic patients with a pseudotumor (7.6 versus 6.2 µg/L [p = 0.37] and 8.3 versus 10.6 µg/L [p = 0.46], respectively). The UCLA scores of asymptomatic patients with a pseudotumor were similar to those of patients without a pseudotumor (6.7 versus 6.6). CONCLUSIONS: The prevalence of asymptomatic taper-corrosion-related pseudotumors on MARS-MRI in this study demonstrated that the absence of symptoms does not exclude the presence of adverse local tissue reactions. Elevated cobalt levels and cobalt/chromium ratios were associated with the presence of pseudotumors in asymptomatic and symptomatic patients. Cross-sectional imaging such as MARS-MRI is indicated for patients with elevated metal-ion levels. A longitudinal study is required to determine whether asymptomatic patients with taper-corrosion-related pseudotumors will develop symptoms with time. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

What Is the Natural History of "Asymptomatic" Pseudotumours in Metal-on-Metal Hip Arthroplasty? Minimum 4-Year Metal Artifact Reduction Sequence Magnetic Resonance Imaging Longitudinal Study.

BACKGROUND: Metal Artifact Reduction Sequence Magnetic Resonance Imaging (MARS-MRI) is an important cross-sectional imaging modality in detection of metal-on-metal (MoM) hip arthroplasty (HA) pseudotumours. Potential evolution of pseudotumours detected by MARS-MRI in "asymptomatic" patients with MoMHA arthroplasty beyond 2 years remains largely unknown. The aims of this longitudinal study were to (1) determine the natural history of pseudotumours in "asymptomatic" MoMHA patients under MARS-MRI surveillance and (2) characterize MRI feature(s) associated with progressive pseudotumours. METHODS: A total of 37 MoMHA (32 patients, mean 56 years old) with pseudotumours on MARS-MRI were evaluated longitudinally using a standardized MARS-MRI protocol. Serum cobalt and chromium levels, pseudotumour size, thickness of the cyst wall, and MRI signal intensity of the abnormality were recorded and analyzed. RESULTS: At minimum of 4-year follow-up (range 49-54 months), 4 Type II pseudotumours (11%) demonstrated MRI evidence of progression. Five Type I pseudotumours (14%) were found to have "regressed." No measurable MRI progression was detected in remaining patients (75%). MRI features associated with progressive pseudotumours included the presence of increased cystic wall thickness and "atypical" mixed fluid signal. MRI pseudotumour progression was not associated with metal ion levels. CONCLUSION: The natural history of type I cystic pseudotumours continues to be nonprogressive in most "asymptomatic" MoMHA patients at minimum 4 years, suggesting the importance of patient symptoms and MRI characteristic features in the clinical decision-making process. Routine follow-up MARS-MRI evaluation of "asymptomatic" patients with low-grade cystic pseudotumours in the absence of interval clinical changes may not be indicated.

Does "6-Clicks" Day 1 Postoperative Mobility Score Predict Discharge Disposition After Total Hip and Knee Arthroplasties?

BACKGROUND: The use of inpatient rehabilitation services after total joint arthroplasty (TJA) is an important driver of episode-of-care costs. We determined the utility of a new standardized instrument collected during the immediate postoperative period, the Activity Measure for Post-Acute Care (AM-PAC) "6-Clicks" Mobility score, in predicting discharge disposition after TJA and its accuracy in estimating prolonged hospital stay, readmissions, and emergency department (ED) visits. METHODS: Using our institutional database, we retrospectively reviewed 744 patients undergoing primary total hip (40%) or knee (60%) arthroplasty for osteoarthritis during 2014. The AM-PAC Mobility score was prospectively collected by physical therapists within 24 hours of surgery. We constructed 2 multivariable logistic regression models for each study outcome: (1) a base model containing age, sex, Charlson Comorbidity Index, and procedure type and (2) the AM-PAC model including the aforementioned variables and this score. The predictive performance of these models was assessed and compared using the area under the receiver operating characteristic (AUC) curve. RESULTS: The AM-PAC model provided better prediction of discharge disposition (AUC = 0.777) than the base model (AUC = 0.716; 22% relative improvement). Although the AM-PAC model performed 32% and 27% better than the base model in estimating prolonged hospital stay and ED visits, the model's predictive performance was poor (prolonged stay: AUC = 0.639; ED visit: AUC = 0.658). The AM-PAC model also showed poor discrimination of readmissions (AUC = 0.657), and there was no relative improvement in predictive performance compared to that of the base model. CONCLUSION: The AM-PAC "6-Clicks" Mobility score is a valid, simple tool for predicting discharge disposition after TJA.

Analysis of Dual Mobility Liner Rim Damage Using Retrieved Components and Cadaver Models.

BACKGROUND: The objective of this study was to assess the retentive rim of retrieved dual mobility liners for visible evidence of deformation from femoral neck contact and to use cadaver models to determine if anterior soft tissue impingement could contribute to such deformation. METHODS: Fifteen surgically retrieved polyethylene liners were assessed for evidence of rim deformation. The average time in vivo was 31.4 months, and all patients were revised for reasons other than intraprosthetic dislocation. Liner interaction with the iliopsoas was studied visually and with fluoroscopy in cadaver specimens using a dual mobility system different than the retrieval study. For fluoroscopic visualization, a metal wire was sutured to the iliopsoas and wires were also embedded into grooves on the outer surface of the liner and the inner head. RESULTS: All retrievals showed evidence of femoral neck contact. The cadaver experiments showed that liner motion was impeded by impingement with the iliopsoas tendon in low flexion angles. When observing the hip during maximum hyperextension, 0°, 15°, and 30° of flexion, there was noticeable tenting of the iliopsoas caused by impingement with the liner. CONCLUSION: Liner rim deformation resulting from contact with the femoral neck likely begins during early in vivo function. The presence of deformation is indicative of a mechanism inhibiting mobility of the liner. The cadaver studies showed that liner motion could be impeded because of its impingement with the iliopsoas. Such soft tissue impingement may be one mechanism by which liner motion is routinely inhibited, which can result in load transfer from the neck to the rim.