STUDY DESIGN: Secondary analysis of a cohort enrolled in a prospective, randomized, longitudinal clinical trial. OBJECTIVES: The single-step test (SST) was evaluated to assess its intertester reliability, validity as a test of activity limitation, and responsiveness to change for patients after unilateral total knee arthroplasty (TKA). The SST was also examined to determine whether it could differentiate between the surgical and nonsurgical lower limbs of patients after unilateral TKA and between the surgical limbs of patients after TKA and the limbs of healthy controls. BACKGROUND: Tests of functional ability for patients recovering from TKA cannot differentiate the contribution of each limb to performance outcome. A test of unilateral limb ability would provide a metric for assessing the surgical lower extremity, without the confounder of the status of the contralateral lower extremity. METHODS: Intertester reliability was assessed between clinicians and between a clinician and a switch mat. Patients who underwent unilateral TKA were tested at initial outpatient physical therapy evaluation, at 3 months after TKA, and at 1 year after TKA. RESULTS: The assessment of function with the SST was determined to be reliable between testers when using a stopwatch. SST times were significantly correlated with other measures of lower extremity functional performance, providing evidence of its validity in patients after TKA. The SST was responsive to treatment in patients after TKA, with improvements in time for test completion. Performance on the SST also differed between limbs of patients after TKA and when comparing the limbs of healthy controls to those of patients after TKA. CONCLUSION: The SST is a reliable measure between testers and a valid and responsive test of activity limitations when assessing unilateral lower extremity impairments in patients after TKA.

J Orthop Sports Phys Ther 2013;43(2):66-73. Epub 16 November 2012. doi:10.2519/jospt.2013.4372

KEY WORDS: function, joint replacement, knee, osteoarthritis

STUDY DESIGN: Prospective cohort study with an age-matched and sex-matched control group. OBJECTIVES: To assess the clinical outcomes of a high-intensity rehabilitation program (HI) compared to those of a group of age-matched and sex-matched controls who underwent a lower intensity rehabilitation program. BACKGROUND: Total knee arthroplasty (TKA) successfully alleviates pain from knee osteoarthritis; but deficits in function can persist long term. Despite these well-known deficits, there is little evidence supporting the use of rehabilitation interventions following TKA. METHODS: Eight patients, who participated in the HI program, were compared to 8 age-matched and sex-matched patients who participated in a lower intensity rehabilitation program (control group). Patients were assessed preoperatively, and at 3.5, 6.5, 12, 26, and 52 weeks postoperatively. Assessment of patients included measures of pain, range of motion (ROM), functional performance, and quadriceps strength and activation. RESULTS: There were no differences in knee ROM and pain between the HI and control groups at any postoperative time point. At the 3.5-week and 12-week (end of rehabilitation) time points, the HI group had better functional performance and quadriceps strength compared to the control group (P<.05). At the 52-week time point, the HI group continued to demonstrate better functional performance compared to the control group (P<.05), along with greater quadriceps strength (P = .08). CONCLUSION: A HI program leads to better short- and long-term strength and functional performance outcomes compared to a lower intensity rehabilitation program. The HI program did not impair knee ROM and did not result in any musculoskeletal injuries in this small group of patients. LEVEL OF EVIDENCE: Therapy, level 2b.

J Orthop Sports Phys Ther 2011;41(12):932-941, Epub 30 September 2011. doi:10.2519/jospt.2011.3734

KEY WORDS: joint replacement, older adults, osteoarthritis, rehabilitation

STUDY DESIGN: Prospective cohort study. OBJECTIVES: To measure changes in muscle strength, range of motion, and function from 2 weeks before to 6 months after total knee arthroplasty (TKA) and compare outcomes with data from a control group consisting of healthy adults. BACKGROUND: Total knee arthroplasty successfully alleviates pain from knee osteoarthritis, but deficits in function can persist long term. How impairments and functional limitations change over the first 6 months after TKA, compared to data from healthy adults, has not been well reported in the literature. METHODS: Twenty-four patients who underwent a primary unilateral TKA were compared to healthy adults (n = 17). All patients participated in a standardized rehabilitation program following surgery. Isometric quadriceps torque was assessed using an electromechanical dynamometer. Range of motion was measured actively and passively. Functional performance was assessed using the stair-climbing test, timed up-and-go test, 6-minute walk test, and single-limb stance time. Patients underwent testing at 2 weeks preoperatively and at 1, 3, and 6 months postoperatively. RESULTS: Compared to healthy older adults, patients performed significantly worse at all times for all measures (P<.05), except for single-limb stance time at 6 months (P>.05). One month postoperatively, patients experienced significant losses from preoperative levels in all outcomes. Patients recovered to preoperative levels by 6 months postoperatively on all measures, except knee flexion range of motion, but still exhibited the same extent of limitation they did prior to surgery. CONCLUSION: The persistent impairments and functional limitations 6 months after TKA with standard rehabilitation suggest that more intensive therapeutic approaches may be necessary to restore function of patients following TKA to the levels of healthy adults. LEVEL OF EVIDENCE: Therapy, level 2b.

J Orthop Sports Phys Ther 2010;40(9):559-567, Epub 6 August 2010. doi:10.2519/jospt.2010.3317

KEY WORDS: joint replacement, older adults, osteoarthritis, rehabilitation

STUDY DESIGN: Case report. BACKGROUND: Following total knee arthroplasty (TKA), restoration of normal quadriceps muscle function is rare. One month after surgery, quadriceps torque (force) is only 40% of preoperative values and quadriceps activation is only 82% of preoperative levels, despite initiating postoperative rehabilitation the day after surgery. Early application of neuromuscular electrical stimulation (NMES) offers a possible approach to minimize loss of quadriceps torque more effectively than traditional rehabilitation exercises alone. CASE DESCRIPTION: A 65-year-old female underwent a right, cemented TKA. Isometric quadriceps and hamstrings muscle torque were measured preoperatively and 3, 6, and 12 weeks after TKA. Quadriceps muscle activation was measured using a doublet interpolation technique at the same time points. The patient participated in a traditional TKA rehabilitation program augmented by NMES, which was initiated 48 hours after surgery and continued twice/day for the first 3 weeks, and once daily for 3 additional weeks. OUTCOMES: Preoperatively, the involved quadriceps produced 75% of the torque of the uninvolved side and demonstrated only 72.9% activation. At 3, 6, and 12 weeks after TKA, quadriceps torque was greater than the preoperative values of the involved side by 16%, 40% and 56%, respectively. Similarly, activation improved to 93.4%, 94.6%, and 93.5% at 3, 6, and 12 weeks after TKA. DISCUSSION: Mitigating quadriceps muscle weakness immediately after TKA using early NMES may improve functional outcomes, because quadriceps weakness has been associated with numerous functional limitations and an increased risk for falls. Despite presenting preoperatively with substantial quadriceps torque and activation deficits, the patient in this case demonstrated improvements in quadriceps function at all time points measured, all of which were superior to those reported in the literature.  The patient also made substantial improvements in functional outcomes, including the Knee Injury and Osteoarthritis Outcome Score (KOOS), 6-minute walk test, timed up and go (TUG) test, stair-climbing test, and the SF-36 Physical Component Score. Appropriately controlled clinical trials will be necessary to determine whether such favorable outcomes following TKA are specifically attributable to the addition of NMES to the rehabilitation program. 

J Orthop Sports Phys Ther. 2007, 37(7):364-371, published online 29 May 2007. doi:10.2519/jospt.2007.2541

KEY WORDS: electrical stimulation, knee replacement, muscle activation, rehabilitation

Study Design: A case series. Objectives: The purpose of this case series was to assess the effect of high-intensity neuromuscular electrical stimulation (NMES) on quadriceps strength and voluntary activation following total knee arthroplasty (TKA). Background: Following TKA, patients exhibit long-term weakness of the quadriceps and diminished functional capacity compared to age-matched healthy controls. The pain and swelling that results from surgery may contribute to quadriceps weakness. The use of high-intensity NMES has previously been shown to be effective in quickly restoring quadriceps strength in patients with weakness after surgery. Methods and Measures: All patients were treated for 6 weeks, 2 to 3 visits per week, in outpatient rehabilitation. Five patients (NMES group) participated in a voluntary exercise program for both knees and NMES for the weaker knee. Three patients (exercise group) participated in a voluntary exercise program for both knees without NMES. For each treatment session, 10 isometric electrically elicited muscle contractions were administered at maximally tolerated doses to the initially weaker leg of the NMES group. Quadriceps strength and muscle activation were repeatedly assessed up to 6 months after surgery using burst superimposition techniques. Results: At 6 months, the weak NMES-treated legs of 4 of 5 patients in the NMES group had surpassed the strength of the contralateral leg. In contrast, none of the weak legs in the exercise group were stronger than the contralateral leg at 6 months. Changes in quadriceps muscle activation mirrored the changes exhibited in strength. Conclusion: When NMES was added to a voluntary exercise program, deficits in quadriceps muscle strength and activation resolved quickly after TKA.

J Orthop Sports Phys Ther. 2004;34(1):21-29. doi:10.2519/jospt.2004.0947

Key Words: geriatric, inhibition, rehabilitation, total knee replacement