Yuo-yu Lee

Weight changes after total hip or knee arthroplasty: prevalence, predictors, and effects on outcomes.

BACKGROUND Conflicting evidence exists with regard to weight loss after total hip arthroplasty or total knee arthroplasty. The purposes of this study were to determine whether patients lose weight after total hip arthroplasty or total knee arthroplasty, whether there are predictors of weight change after total hip arthroplasty or total knee arthroplasty, and whether weight changes after total hip arthroplasty or total knee arthroplasty affect patient-reported outcomes. METHODS Using our institutional registry, we evaluated the two-year change in self-reported body mass indices for all patients who underwent elective, unilateral total hip arthroplasty or total knee arthroplasty for osteoarthritis. A 5% change in body mass index was considered clinically meaningful. Patient-reported outcomes were compared between patients who underwent total hip arthroplasty and those who underwent total knee arthroplasty and between obesity classes, on the basis of whether patients gained, lost, or maintained weight. RESULTS We reviewed 3893 total hip arthroplasties and 3036 total knee arthroplasties. Of the patients who underwent total joint arthroplasty, 73% (2850 patients) in the total hip arthroplasty group and 69% (2090 patients) in the total knee arthroplasty group demonstrated no change in body mass index. Patients who underwent total knee arthroplasty were more likely to lose weight than patients who underwent total hip arthroplasty. Increasing preoperative obesity correlated with a greater likelihood of weight loss. Patients who underwent total knee arthroplasty and lost weight demonstrated better clinical outcome scores, but weight gain in general was associated with inferior clinical outcomes. Greater body mass index, total knee arthroplasty, and female sex were significant predictors of weight loss (p < 0.05). Better preoperative functional status was significantly associated with a lower likelihood of weight gain (p < 0.05). CONCLUSIONS Most patients maintained their body mass index after total hip arthroplasty or total knee arthroplasty. Female patients, patients with higher preoperative body mass index, and those who underwent total knee arthroplasty were more likely to lose weight after surgery. LEVEL OF EVIDENCE Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Validation of the KOOS, JR: A Short-form Knee Arthroplasty Outcomes Survey.

BackgroundMedicare is rapidly moving toward using patient-reported outcome measures (PROMs) for outcomes assessment and justification of orthopaedic and other procedures. Numerous measures have been developed to study knee osteoarthritis (OA); however, many of these surveys are long, disruptive to clinic flow, and result in incomplete data capture and/or low followup rates. The Knee injury and Osteoarthritis Outcome (KOOS) physical function short-form (KOOS-PS), while shorter, ignores pain, which is a primary concern of patients with advanced knee OA.Questions/purposesOur objective was to derive and validate a short-form survey focused on the patient with end-stage knee OA undergoing TKA.MethodsUsing our hospital’s knee replacement registry, we retrospectively identified 2291 patients with knee OA who underwent primary unilateral TKA and had completed preoperative and 2-year postoperative PROMs. We assessed 30 items from the 42-item KOOS that were quantitatively most difficult for patients to perform before TKA and qualitatively most relevant to patients with end-stage knee OA. Rasch analysis identified the KOOS, JR, a seven-item instrument, representing a single dimension, which we define as “knee health” because it reflects aspects of pain, symptom severity, and activities of daily living (ADL) including movements or activities that are directly relevant and difficult for patients with advanced knee OA. We assessed the internal consistency, external validity (versus KOOS and WOMAC domains), responsiveness, and floor and ceiling effects of the KOOS, JR. External validation was performed using calculated KOOS, JR scores in collaboration with a nationally representative joint replacement registry, the Function and Outcomes Research for Comparative Effectiveness in Total Joint Replacement (FORCE-TJR).ResultsInternal consistency for the KOOS, JR was high (Person Separation Index, 0.84; and 0.85 [FORCE]), external validity against other validated knee surveys was excellent (Spearman correlation coefficient, ρ 0.54–0.91), particularly for the KOOS pain (ρ 0.89 [95% CI, 0.88–0.91] Hospital for Special Surgery [HSS]; and 0.91 [95% CI, 0.90–0.93] [FORCE]) and KOOS ADL (ρ 0.87 [95% CI, 0.85–0.88] [HSS]; and 0.84 [95% CI, 0.81–0.87] [FORCE]). The KOOS, JR responsiveness (standardized response means, 1.79 [95% CI, 1.70–1.88] [HSS]; and 1.70 [95% CI, 1.54–1.86] [FORCE]) was high and floor 0.4–1.2%) and ceiling (18.8–21.8%) effects were favorable.ConclusionsThe new short knee PROM, the KOOS, JR, provides a single score representing “knee health” as it combines pain, symptoms, and functional limitations in a single score. This short-form PROM is patient-relevant and efficient.Level of EvidenceLevel III, diagnostic study.

Validation of the HOOS, JR: A Short-form Hip Replacement Survey

BackgroundPatient-reported outcome measures (PROMs) are increasingly in demand for outcomes evaluation by hospitals, administrators, and policymakers. However, assessing total hip arthroplasty (THA) through such instruments is challenging because most existing measures of hip health are lengthy and/or proprietary.Questions/purposesThe objective of this study was to derive a patient-relevant short-form survey based on the Hip disability and Osteoarthritis Outcome Score (HOOS), focusing specifically on outcomes after THA.MethodsWe retrospectively evaluated patients with hip osteoarthritis who underwent primary unilateral THA and who had completed preoperative and 2-year postoperative PROMs using our hospital’s hip replacement registry. The 2-year followup in this population was 81% (4308 of 5351 patients). Of these, 2371 completed every item on the HOOS before surgery and at 2 years, making them eligible for the formal item reduction analysis. Through semistructured interviews with 30 patients, we identified items in the HOOS deemed qualitatively most important to patients with hip osteoarthritis. The original HOOS has 40 items, the four quality-of-life items were excluded a priori, five were excluded for being redundant, and one was excluded based on patient-relevance surveys. The remaining 30 items were evaluated using Rasch modeling to yield a final six-item HOOS, Joint Replacement (HOOS, JR), representing a single construct of “hip health.” We calculated HOOS, JR scores for the Hospital for Special Surgery (HSS) cohort and validated this new score for internal consistency, external validity (versus HOOS and WOMAC domains), responsiveness to THA, and floor and ceiling effects. Additional external validation was performed using calculated HOOS, JR scores in collaboration with the Function and Outcomes Research for Comparative Effectiveness in Total Joint Replacement (FORCE-TJR) nationally representative joint replacement registry (n = 910).ResultsThe resulting six-item PROM (HOOS, JR) retained items only from the pain and activities of daily living domains. It showed high internal consistency (Person Separation Index, 0.86 [HSS]; 0.87 [FORCE]), moderate to excellent external validity against other hip surveys (Spearman’s correlation coefficient, 0.60–0.94), very high responsiveness (standardized response means, 2.03 [95% CI, 1.84–2.22] [FORCE]; and 2.38 [95% CI, 2.27–2.49] [HSS]), and favorable floor (0.6%–1.9%) and ceiling (37%–46%) effects. External validity was highest for the HOOS pain (Spearman’s correlation coefficient, 0.87 [95% CI, 0.86–0.89] [HSS]; and 0.87 [95% CI, 0.84–0.90] [FORCE]) and HOOS activities of daily living (Spearman’s correlation coefficient, 0.94 [95% CI, 0.93–0.95] [HSS]; and 0.94 [95% CI, 0.93–0.96] [FORCE]) domains in the HSS validation cohort and the FORCE-TJR cohort.ConclusionsThe HOOS, JR provides a valid, reliable, and responsive measure of hip health for patients undergoing THA. This short-form PROM is patient relevant and efficient.Level of EvidenceLevel III, diagnostic study.

Obese Patients Undergoing Total Knee Arthroplasty Have Distinct Preoperative Characteristics: An Institutional Study of 4718 Patients

Obesity affects a disproportionate proportion of total knee arthroplasty (TKA) patients. Our study explores pre-operative characteristics between obese and non-obese patients undergoing TKA surgery. A cohort of 4718 osteoarthritic patients, undergoing primary TKA, was studied. Patients were stratified according to BMI classes. Each class was compared in terms of age, race, gender, level of education, insurance status, pre-operative WOMAC, SF-36, and Elixhauser comorbidities. There was a positive relationship between BMI and female gender, non-white race, Medicaid, private insurance, and self-pay. A negative relationship was observed between BMI and age, Medicare, WOMAC and SF-36. Obese TKA candidates differ from their non-obese counterparts in a number of demographic, socioeconomic, and clinical characteristics.

All-Cause In-Hospital Complications and Urinary Tract Infections Increased in Obese Patients Undergoing Total Knee Arthroplasty

The aims of this study were to determine the rates of in-hospital complications, discharge disposition, and length of stay for patients with varying degrees of obesity. We identified 4718 patients who underwent TKA between 2007 and 2010. After adjusting for age, sex, race, education, Deyo-Charlson comorbidity index, insurance, and discharge disposition, obese patients were more likely to develop any in-hospital complication (6.4% vs. 4.8%, respectively; P = 0.0097; OR = 1.5). When analyzing specific in-hospital complications, obese patients were more likely to suffer urinary tract infections (P = 0.0029). They were also more likely to be discharged to a rehabilitation facility (P = 0.001). There was no significant difference in other postoperative complications. In summary, obese patients undergoing primary TKA are at increased risk for all-cause in-hospital complications and urinary tract infections and are more likely to be discharged to a rehabilitation facility.

The Position of the Patella and Extensor Mechanism Affects Intraoperative Compartmental Loads During Total Knee Arthroplasty A Pilot Study Using Intraoperative Sensing to Guide Soft Tissue Balance

UNLABELLED The achievement of a well-balanced total knee arthroplasty is necessary for long-term success. We hypothesize that the dislocation of the patella during surgery affects the distribution of loads in the medial and lateral compartments. Intraoperative load sensors were used to record medial and lateral compartment loads in 56 well-balanced TKAs. Loads were recorded in full extension, relaxed extension, at 45 and 90° of flexion at full gravity-assisted flexion, with the patella in four different positions: dislocated (everted and not), located, and located and secured with two retinacular sutures. The loads in the lateral compartment in flexion were higher with a dislocated patella than with a located patella (P<0.001). A lateralized extensor mechanism artificially increases in the lateral compartment loads in flexion during TKA surgery. Instruments that allow intraoperative soft tissue balance with the patella in a physiologic position are more likely to replicate postoperative compartment loads. LEVEL OF EVIDENCE II (prospective comparative study).

Range of motion and function are not affected by increased post constraint in patients undergoing posterior stabilized total knee arthroplasty

BACKGROUND Constrained primary total knee arthroplasty (TKA) can provide stability in the face of incompetent collateral structures or irreconcilable flexion-extension imbalances. However, little is known about its effect on overall knee range of motion (ROM). This study determines whether TKA with increased constraint affects postoperative ROM. METHODS Patients undergoing primary TKA using either posterior stabilized (PS) or constrained condylar knee (CCK) inserts were match-paired based on body mass index, preoperative ROM, and direction and severity of the coronal deformity, yielding 68 pairs. ROM and Knee Society Score (KSS) were obtained preoperatively and at 6 weeks, 4 months, and 1 year. RESULTS When the 68 matched pairs were considered, all outcome variables related to ROM between the PS and CCK groups at each of the postoperative intervals were similar. Additionally, both the individual items and combined scores of the KSS were similar between groups at all time points. CONCLUSIONS We demonstrate that the use of increased constraint does not affect ROM, relief of pain, or function after TKA. LEVEL OF EVIDENCE Level III (retrospective case-controlled study, based on prospectively collected data).

Disparities in TKA Outcomes: Census Tract Data Show Interactions Between Race and Poverty

BackgroundRace is an important predictor of TKA outcomes in the United States; however, analyses of race can be confounded by socioeconomic factors, which can result in difficulty determining the root cause of disparate outcomes after TKA.Questions/purposesWe asked: (1) Are race and socioeconomic factors at the individual level associated with patient-reported pain and function 2 years after TKA? (2) What is the interaction between race and community poverty and patient-reported pain and function 2 years after TKA?MethodsWe identified all patients undergoing TKA enrolled in a hospital-based registry between 2007 and 2011 who provided 2-year outcomes and lived in New York, Connecticut, or New Jersey. Of patients approached to participate in the registry, more than 82% consented and provided baseline data, and of these patients, 72% provided 2-year data. Proportions of patients with complete followup at 2 years were lower among blacks (57%) than whites (74%), among patients with Medicaid insurance (51%) compared with patients without Medicaid insurance (72%), and among patients without a college education (67%) compared with those with a college education (71%). Our final study cohort consisted of 4035 patients, 3841 (95%) of whom were white and 194 (5%) of whom were black. Using geocoding, we linked individual-level registry data to US census tracts data through patient addresses. We constructed a multivariate linear mixed-effect model in multilevel frameworks to assess the interaction between race and census tract poverty on WOMAC pain and function scores 2 years after TKA. We defined a clinically important effect as 10 points on the WOMAC (which is scaled from 1 to 100 points, with higher scores being better).ResultsRace, education, patient expectations, and baseline WOMAC scores are all associated with 2-year WOMAC pain and function; however, the effect sizes were small, and below the threshold of clinical importance. Whites and blacks from census tracts with less than 10% poverty have similar levels of pain and function 2 years after TKA (WOMAC pain, 1.01 ± 1.59 points lower for blacks than for whites, p = 0.53; WOMAC function, 2.32 ± 1.56 lower for blacks than for whites, p = 0.14). WOMAC pain and function scores 2 years after TKA worsen with increasing levels of community poverty, but do so to a greater extent among blacks than whites. Disparities in pain and function between blacks and whites are evident only in the poorest communities; decreasing in a linear fashion as poverty increases. In census tracts with greater than 40% poverty, blacks score 6 ± 3 points lower (worse) than whites for WOMAC pain (p = 0.03) and 7 ± 3 points lower than whites for WOMAC function (p = 0.01).ConclusionsBlacks and whites living in communities with little poverty have similar patient-reported TKA outcomes, whereas in communities with high levels of poverty, there are important racial disparities. Efforts to improve TKA outcomes among blacks will need to address individual- and community-level socioeconomic factors.Level of EvidenceLevel III, therapeutic study.

Short-Term Metal Ion Trends Following Removal of Recalled Modular Neck Femoral Stems.

Elevated serum metal ions have been well documented with the Rejuvenate modular neck femoral stem (Stryker, Mahwah, NJ); however, the rate at which ion levels decline following revision is less clear. This study included fifty-nine consecutive revisions of Rejuvenate stems for symptomatic ALTR. Blood tests prior to revision and postoperatively at 6weeks, 3months, 6months, and 1year measured serum cobalt and chromium concentrations, ESR, and CRP. At six weeks following revision of a unilateral Rejuvenate, cobalt and chromium levels dropped from preoperative levels by 67% and 42%, respectively. At three months, cobalt levels declined to 19% of preoperative values, but chromium levels remained stable. With this information, surgeons can set realistic expectations for serum metal ion levels following Rejuvenate stem revision.

Patient-Reported Allergies Are Associated With Poorer Patient Satisfaction and Outcomes After Lower Extremity Arthroplasty: A Retrospective Cohort Study

Anecdotal evidence suggests that patient-reported allergies (PRAs) may exhibit prognostic value for patient-reported outcomes after lower extremity arthroplasty. This studys purpose was to investigate associations between PRAs, patient satisfaction and outcomes after total hip arthroplasty (THA) and total knee arthroplasty (TKA). PRAs in 274 patients undergoing primary THA and 257 patients receiving primary TKA were reviewed retrospectively. Satisfaction scores, baseline Western Ontario and McMaster Universities Arthritis Index (WOMAC), 2-year postoperative WOMAC and length-of-stay (LOS) were analyzed with PRAs. Increasing number of PRAs was significantly associated with worse satisfaction scores and worse WOMAC scores for TKA and THA, and it was significantly associated with increased LOS for TKA. These results may have implications for patient counseling and risk-adjusted outcome models.