Predictors of multidimensional functional outcomes after total knee arthroplasty.

Multiple assessments are used clinically after total knee arthroplasty (TKA) including self-report, performance tasks, and physical activity levels. It is unclear if these different functional assessments are interchangeable or if they measure different constructs. The objective of this study was to characterize different functional measures before and after TKA. We characterized function before and after TKA using perceived function (KOOS ADL), physical performance (gait speed), and daily activity (steps/day via accelerometry); compared function in people undergoing TKA to age-matched healthy controls; and examined characteristics of those undergoing TKA for potential predictors of postoperative function. Prior to TKA, all three functional assessments were significantly lower for participants than those of healthy controls and each measure remained lower for participants than for controls postoperatively. All three functional assessments developed differently over time postoperatively. Each functional outcome had a unique set of predictors. Perceived function was predicted primarily by anxiety and depression, physical performance was most strongly predicted by age, and daily activity was chiefly predicted by BMI. Pressure pain threshold was a common predictor across all models. Functional limitations exist preoperatively and persist postoperatively across different measures in people undergoing TKA when compared to those measures in healthy controls. Functional outcomes after TKA are different depending on the functional measure utilized, implying that different constructs underlie each measure. Multiple functional measures should be assessed to provide a more comprehensive assessment of function after TKA. Further work should assess the impact of interventions designed to treat modifiable predictors of postoperative TKA function. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2790-2798, 2017.

Prevalence of gluteus medius weakness in people with chronic low back pain compared to healthy controls.

PURPOSE: Clinical observation suggests that hip abductor weakness is common in patients with low back pain (LBP). The purpose of this study is to describe and compare the prevalence of hip abductor weakness in a clinical population with chronic non-specific LBP and a matched sample without LBP. METHODS: One hundred fifty subjects with chronic non-specific LBP and a matched cohort of 75 control subjects were recruited. A standardized back and hip physical exam was performed. Specifically tensor fascia lata, gluteus medius, and gluteus maximus strength were assessed with manual muscle testing. Functional assessment of the hip abductors was performed with assessment for the presence of the Trendelenburg sign. Palpation examination of the back, gluteal and hip region was performed to try and reproduce the subject's pain complaint. Friedman's test or Cochran's Q with post hoc comparisons adjusted for multiple comparisons was used to compare differences between healthy controls and people with chronic low back pain for both the affected and unaffected sides. Mann-Whitney U was used to compare differences in prevalence between groups. Hierarchical linear regression was used to identify predictors of LBP in this sample. RESULTS: Gluteus medius is weaker in people with LBP compared to controls or the unaffected side (Friedman's test, p < 0.001). The Trendelenburg sign is more prevalent in subjects with LBP than controls (Cochran's Q, p < 0.001). There is more palpation tenderness over the gluteals, greater trochanter, and paraspinals in people with low back pain compared to controls (Cochran's Q, p < 0.001). Hierarchical linear regression, with BMI as a covariate, demonstrated that gluteus medius weakness, low back regional tenderness, and male sex were predictive of LBP in this sample. CONCLUSION: Gluteus medius weakness and gluteal muscle tenderness are common symptoms in people with chronic non-specific LBP. Future investigations should validate these findings with quantitative measures as well as investigate the effect of gluteus medius strengthening in people with LBP.

Women with knee osteoarthritis have more pain and poorer function than men, but similar physical activity prior to total knee replacement.

BACKGROUND: Osteoarthritis of the knee is a major clinical problem affecting a greater proportion of women than men. Women generally report higher pain intensity at rest and greater perceived functional deficits than men. Women also perform worse than men on function measures such as the 6-minute walk and timed up and go tests. Differences in pain sensitivity, pain during function, psychosocial variables, and physical activity levels are unclear. Further the ability of various biopsychosocial variables to explain physical activity, function and pain is unknown. METHODS: This study examined differences in pain, pain sensitivity, function, psychosocial variables, and physical activity between women and men with knee osteoarthritis (N = 208) immediately prior to total knee arthroplasty. We assessed: (1) pain using self-report measures and a numerical rating scale at rest and during functional tasks, (2) pain sensitivity using quantitative sensory measures, (3) function with self-report measures and specific function tasks (timed walk, maximal active flexion and extension), (4) psychosocial measures (depression, anxiety, catastrophizing, and social support), and (5) physical activity using accelerometry. The ability of these mixed variables to explain physical activity, function and pain was assessed using regression analysis. RESULTS: Our findings showed significant differences on pain intensity, pain sensitivity, and function tasks, but not on psychosocial measures or physical activity. Women had significantly worse pain and more impaired function than men. Their levels of depression, anxiety, pain catastrophizing, social support, and physical activity, however, did not differ significantly. Factors explaining differences in (1) pain during movement (during gait speed test) were pain at rest, knee extension, state anxiety, and pressure pain threshold; (2) function (gait speed test) were sex, age, knee extension, knee flexion opioid medications, pain duration, pain catastrophizing, body mass index (BMI), and heat pain threshold; and (3) physical activity (average metabolic equivalent tasks (METS)/day) were BMI, age, Short-Form 36 (SF-36) Physical Function, Kellgren-Lawrence osteoarthritis grade, depression, and Knee Injury and Osteoarthritis Outcome Score (KOOS) pain subscale. CONCLUSIONS: Women continue to be as physically active as men prior to total knee replacement even though they have significantly more pain, greater pain sensitivity, poorer perceived function, and more impairment on specific functional tasks.