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Preoperative Quadriceps Strength Predicts Functional Ability One Year After Total Knee Arthroplasty
RYAN L. MIZNER, STEPHANIE C. PETTERSON, JENNIFER E. STEVENS, MICHAEL J. AXE, and LYNN SNYDER-MACKLER
ABSTRACT. Methods. Forty subjects (mean age 63 ± 8 yrs, body mass index 29.4 kg/m2 ± 4.2) were tested 2 weeks before and one year after TKA. Quadriceps strength was measured isometrically, pain was quantified using the Medical Outcome Study Short-Form 36 (SF-36) bodily pain subset, and knee flexion range of motion (ROM) was assessed by goniometer. Performance based functional assessment included the Timed Up and Go test (TUG) and a timed Stair Climbing Test (SCT). The Knee Outcome Survey (KOS) and the SF-36 questionnaires were used to quantify perceived function. The ability of preoperative factors to predict postoperative outcomes was analyzed using hierarchical regression. Differences in means before and one year after surgery were analyzed using paired t tests. Results. Significant improvements were found in all functional measures assessed (p < 0.001). Preoperative quadriceps strength accounted for the bulk of the variance in the one-year SCT and the TUG (p < 0.001), but did not achieve significance in predicting one-year questionnaire scores (p > 0.05). Neither preoperative pain nor knee ROM were significant predictors of any functional measure (p > 0.05). Conclusion. Preoperative quadriceps strength plays a dominant role in predicting one-year SCT and TUG functional measures, but it is not a good predictor of score on self-report questionnaires. Preoperative bodily pain and knee flexion ROM are poor predictors of all functional outcome measures. (J Rheumatol 2005;32:1533-9) Key Indexing Terms:
OSTEOARTHRITIS
From the Department of Physical Therapy, University of Delaware, Newark, Delaware; Veterans Affairs RR&D Brain Rehabilitation Research Center, Malcom Randall VA Medical Center, Gainesville, Florida; and First State Orthopaedics, Newark, Delaware, USA. Supported by NIH Grant no. R01HD041055-01 and Grant no. T32 HD07490, PODS I (to Dr. Mizner) and PODS II scholarships (to Dr. Stevens) from The Foundation for Physical Therapy. R.L. Mizner, MPT, PhD, Department of Physical Therapy, University of Delaware (current address: Department of Physical Therapy, Eastern Washington University, Spokane, WA, USA); S.C. Petterson, MPT, Department of Physical Therapy, University of Delaware; J.E. Stevens, MPT, PhD, Malcom Randall VA Medical Center; M.J. Axe, MD, Department of Physical Therapy, University of Delaware, First State Orthopaedics; L. Snyder-Mackler, PT, ATC, ScD, Department of Physical Therapy, University of Delaware. Address reprint requests to Dr. L. Snyder-Mackler, Department of Physical Therapy, University of Delaware, 301 McKinly Laboratory, Newark, DE 19716. E-mail: smack@udel.edu Accepted for publication March 4, 2005. |