Alexandra B. Gil

A Balance Exercise Program Appears to Improve Function for Patients With Total Knee Arthroplasty: A Randomized Clinical Trial

Background Patients with total knee arthroplasty (TKA) have impaired balance and movement control. Exercise interventions have not targeted these impairments in this population. Objectives The purposes of this study were: (1) to determine the feasibility of applying a balance exercise program in patients with TKA, (2) to investigate whether a functional training (FT) program supplemented with a balance exercise program (FT+B program) could improve physical function compared with an FT program alone in a small group of individuals with TKA, and (3) to test the methods and calculate sample size for a future randomized trial with a larger study sample. Design This study was a double-blind, pilot randomized clinical trial. Setting The study was conducted in the clinical laboratory of an academic center. Participants The participants were 43 individuals (30 female, 13 male; mean age=68 years, SD=8) who underwent TKA 2 to 6 months prior to the study. Interventions The interventions were 6 weeks (12 sessions) of a supervised FT or FT+B program, followed by a 4-month home exercise program. Measurements Feasibility measures included pain, stiffness, adherence, and attrition. The primary outcome measure was a battery of physical performance tests: self-selected gait speed, chair rise test, and single-leg stance time. Secondary outcome measures were the Western Ontario and McMaster Universities Osteoarthritis Index and the Lower Extremity Functional Scale. Results Feasibility of the balance training in people with TKA was supported by high exercise adherence, a relatively low dropout rate, and no adverse events. Both groups demonstrated clinically important improvements in lower-extremity functional status. The degree of improvement seemed higher for gait speed, single-leg stance time, and stiffness in the FT+B group compared with the FT group. Limitations Due to the pilot nature of the study, differences between groups did not have adequate power to show statistical significance. Conclusions There is a need for conducting a larger randomized controlled trial to test the effectiveness of an FT+B program after TKA.

Agility and Perturbation Training Techniques in Exercise Therapy for Reducing Pain and Improving Function in People With Knee Osteoarthritis: A Randomized Clinical Trial

Background Impairment-based exercise programs have yielded only small to moderate benefits in reducing pain and improving function in people with knee osteoarthritis (OA). It has previously been proposed that adding agility and perturbation training to exercise programs for people with knee OA may improve treatment effects for pain and function. Objective The purpose of this study was to examine the effectiveness of adding agility and perturbation techniques to standard exercise therapy compared with the standard exercise program alone for people with knee OA. Design This was a single-blinded randomized controlled trial. Setting The study was conducted in the outpatient physical therapy clinic of a large, university-based health center. Participants One hundred eighty-three people with knee OA (122 women, 61 men) participated. Interventions Participants were randomly assigned to either a group that received agility and perturbation training with standard exercise therapy or a group that received only the standard exercise program. Measurements The outcome measures were self-reported knee pain and function, self-reported knee instability, a performance-based measure of function, and global rating of change. Results Although both groups exhibited improvement in self-reported function and in the global rating of change at the 2-, 6-, and 12-month follow-up periods, there were no differences between groups on these outcomes. There was no reduction in knee pain or improvement in performance-based function in either group. Limitations It is possible that more-intense application of the interventions or application of the interventions to participants with knee OA who were at greater risk for falling may have yielded additive effects of the agility and perturbation training approach. Conclusions Both intervention groups exhibited improvement in self-reported function and the global rating of change. Our results, however, did not support an additive effect of agility and perturbation training with standard exercise therapy in our sample of individuals with knee OA. Further study is needed to determine whether there are subgroups of individuals who might achieve an added benefit with this approach.

Interrater Reliability and Validity of the Stair Ascend/Descend Test in Subjects With Total Knee Arthroplasty

OBJECTIVE (1) To determine the interrater reliability and measurement error of an 11-step stair ascend/descend test (STTotal-11) and stair up (ascend) test (STUp-11); (2) to seek evidence for the STTotal-11 and STUp-11 as valid measures of physical function by determining if they relate to measures of physical function and do not relate to measures not of physical function; and (3) to explore if the STTotal-11 and STUp-11 scores relate to lower-extremity muscle weakness and knee range of motion (ROM) in subjects with total knee arthroplasty (TKA). DESIGN Cross-sectional study. SETTING Academic center. PARTICIPANTS Subjects (N=43, 30 women; mean age, 68+/-8y) with unilateral TKA. INTERVENTIONS Not applicable. MAIN OUTCOME MEASURES STTotal-11 and STUp-11 were performed twice, and scores were compared with scores on 4 lower extremity performance-based tasks, 2 patient-reported questionnaires of physical function, 3 psychologic factors, knee ROM, and strength of quadriceps, hip extensors, and abductors. RESULTS Intraclass correlation coefficient was .94 for both the STTotal-11 and STUp-11, standard error of measurements were 1.14 seconds and .82 seconds, and minimum detectable change associated with 90% confidence interval was 2.6 seconds and 1.9 seconds, respectively. Correlations between stair tests and performance-based measures and knee and hip muscle strength ranged from Pearson correlation coefficient (r)=.40 to .78. STTotal-11 and STUp-11 had a small correlation with one of the patient-reported measures of physical function. Stair tests were not associated with psychologic factors and knee extension ROM and were associated with knee flexion ROM. CONCLUSIONS STTotal-11 and STUp-11 have good interrater reliability and minimum detectable changes adequate for clinical use. The pattern of associations supports the validity of the stair tests in TKA.

Contribution of Hip Abductor Strength to Physical Function in Patients With Total Knee Arthroplasty

Background Investigating modifiable factors that contribute to functional limitations in patients with total knee arthroplasty (TKA) may guide changes in rehabilitation protocols and improve functional outcomes. Whereas quadriceps muscle weakness has been demonstrated to contribute to functional limitations in TKA, the role of hip abductor weakness has not received attention. Objective The purpose of this study was to determine whether hip abductor strength (force-generating capacity) contributes to physical function beyond what can be explained by quadriceps muscle strength in patients after a TKA. Design A cross-sectional design was used in the study. Setting The study was conducted in a clinical laboratory at an academic center. Patients Thirty-one people with TKA (74% female; mean age=68 years, SD=8; mean body mass index=31 kg/m2, SD=5) participated in the study. Measurements Strength of quadriceps muscles and hip abductors was measured using an isokinetic dynamometer. Performance-based physical function was assessed with 4 measures: self-selected walking speed, the Figure-of-8 Walk Test, the Stair Ascend/Descend Test, and the 5-Chair Rise Test. Self-reported physical function was assessed with the Western Ontario and McMaster Universities Osteoarthritis Index Physical Function Subscale. Results In hierarchical regression models, after accounting for demographic and anthropometric factors, quadriceps muscle strength was associated with performance on the Stair Ascend/Descend Test. After accounting for demographic, anthropometric, and quadriceps strength, hip abductor strength was associated with performance on the Stair Ascend/Descend Test, the Figure-of-8 Walk Test, and the 5-Chair Rise Test. Limitations The study design precluded ascertainment of causal relationships. Conclusions After TKA, hip abductor strength influenced physical function in participants more than did demographic or anthropometric measures or quadriceps strength. Longitudinal studies with larger samples are warranted. If findings are replicated, they will justify targeting the hip abductors during rehabilitation after TKA.

Responsiveness of the activities of daily living scale of the knee outcome survey and numeric pain rating scale in patients with patellofemoral pain.

OBJECTIVE To assess internal and external responsiveness of the Activity of Daily Living Scale of the Knee Outcome Survey and Numeric Pain Rating Scale on patients with patellofemoral pain. DESIGN One group pre-post design. SUBJECTS A total of 60 individuals with patellofemoral pain (33 women; mean age 29.9 (standard deviation 9.6) years). METHODS The Activity of Daily Living Scale and the Numeric Pain Rating Scale were assessed before and after 8 weeks of physical therapy program. Patients completed a global rating of change scale at the end of therapy. The standardized effect size, Guyatt responsiveness index, and the minimum clinical important difference were calculated. RESULTS Standardized effect size of the Activity of Daily Living Scale was 0.63, Guyatt responsiveness index was 1.4, area under the curve was 0.83 (95% confidence interval: 0.72, 0.94), and the minimum clinical important difference corresponded to an increase of 7.1 percentile points. Standardized effect size of the Numeric Pain Rating Scale was 0.72, Guyatt responsiveness index was 2.2, area under the curve was 0.80 (95% confidence interval: 0.70, 0.92), and the minimum clinical important difference corresponded to a decrease of 1.16 points. CONCLUSION Information from this study may be helpful to therapists when evaluating the effectiveness of rehabilitation intervention on physical function and pain, and to power future clinical trials on patients with patellofemoral pain.

Effect of baseline quadriceps activation on changes in quadriceps strength after exercise therapy in subjects with knee osteoarthritis

OBJECTIVE To examine whether pretreatment magnitude of quadriceps activation (QA) helps predict changes in quadriceps strength after exercise therapy in subjects with knee osteoarthritis (OA). We hypothesized that subjects with lower magnitudes of QA (greater failure of muscle activation) would have smaller gains in strength compared with those with higher magnitudes of QA following exercise therapy. METHODS One hundred eleven subjects with knee OA (70 women) participated. Baseline measures included demographic information, quadriceps muscle strength, and QA using a burst-superimposition isometric torque test. Following baseline testing, subjects underwent a 6-week supervised exercise program designed to improve strength, range of motion, balance and agility, and physical function. On completion of the program, quadriceps strength and QA were reassessed. Multiple regression analysis was used to determine whether baseline QA predicted quadriceps strength scores at the 2-month followup. RESULTS Bivariate correlations demonstrated that baseline QA was significantly associated with quadriceps strength at baseline (rho = 0.30, P < 0.01) and 2-month followup (rho = 0.23, P = 0.01). Greater magnitude of baseline QA correlated with higher strength. While controlling for baseline quadriceps strength and type of exercise therapy, the level of QA did not predict quadriceps strength at the 2-month followup (beta = -0.04, P = 0.18). CONCLUSION Baseline QA did not predict changes in quadriceps strength following exercise therapy. Measurement of QA using the central activation ratio method does not appear to be helpful in identifying subjects with knee OA who will have difficulty improving quadriceps strength with exercise therapy.

Association of Severity of Coexisting Patellofemoral Disease With Increased Impairments and Functional Limitations in Patients With Knee Osteoarthritis

To evaluate the association between severity of coexisting patellofemoral (PF) disease with lower extremity impairments and functional limitations in patients with tibiofemoral (TF) osteoarthritis (OA).

Are the kinematics of the knee joint altered during the loading response phase of gait in individuals with concurrent knee osteoarthritis and complaints of joint instability? A dynamic stereo X-ray study

BACKGROUND Joint instability has been suggested as a risk factor for knee osteoarthritis and a cause of significant functional decline in those with symptomatic disease. However, the relationship between altered knee joint mechanics and self-reports of instability in individuals with knee osteoarthritis remains unclear. METHODS Fourteen subjects with knee osteoarthritis and complaints of joint instability and 12 control volunteers with no history of knee disease were recruited for this study. Dynamic stereo X-ray technology was used to assess the three-dimensional kinematics of the knee joint during the loading response phase of gait. FINDINGS Individuals with concurrent knee osteoarthritis and joint instability demonstrated significantly reduced flexion and internal/external rotation knee motion excursions during the loading response phase of gait (P<0.01), while the total abduction/adduction range of motion was increased (P<0.05). In addition, the coronal and transverse plane alignment of the knee joint at initial contact was significantly different (P<0.05) for individuals with concurrent knee osteoarthritis and joint instability. However, the anteroposterior and mediolateral tibiofemoral joint positions at initial contact and the corresponding total joint translations were similar between groups during the loading phase of gait. INTERPRETATIONS The rotational patterns of tibiofemoral joint motion and joint alignments reported for individuals with concurrent knee osteoarthritis and joint instability are consistent with those previously established for individuals with knee osteoarthritis. Furthermore, the findings of similar translatory tibiofemoral motion between groups suggest that self-reports of episodic joint instability in individuals with knee osteoarthritis may not necessarily be associated with adaptive alterations in joint arthrokinematics.

Change in knee cartilage volume in individuals completing a therapeutic exercise program for knee osteoarthritis.

STUDY DESIGN Prospective cohort study. OBJECTIVES To characterize knee cartilage change in individuals with knee osteoarthritis (KOA) who have completed a therapeutic exercise program. BACKGROUND While therapeutic exercise is frequently used successfully to improve pain and function in individuals with KOA, no studies have reported the volume of cartilage change or individual factors that may impact volume of cartilage change in those completing an exercise program for KOA. METHODS Thirteen individuals with KOA underwent magnetic resonance imaging to quantify cartilage volume change in the weight-bearing regions of the medial and lateral femoral condyles and the entire surface of the tibial plateaus from baseline to 1-year follow-up. Body structure and function measures were taken for body mass index, knee axis alignment, knee motion, and knee strength. Activity limitations and activity levels were also measured prior to the therapeutic exercise program, using the Western Ontario and McMaster Universities Osteoarthritis Index and the Physical Activity Scale for the Elderly. At 6 months from baseline, follow-up clinical measurements of knee strength and motion were performed. At 1 year from baseline, imaging of the knee cartilage and knee alignment were performed, and participants completed the Western Ontario and McMaster Universities Osteoarthritis Index and Physical Activity Scale for the Elderly. RESULTS The central region of the medial femoral condyle (cMF) had a median volume of cartilage loss of 3.8%. The other 3 knee tibiofemoral articular surfaces had minimal median cartilage volume change. Individuals were dichotomized into progressors (n = 6) and nonprogressors (n = 7), based on the standard error of measurement of cartilage volume change for the cMF. Progressors were younger, had a larger body mass index, had a higher Kellgren-Lawrence grade in the medial compartment of the knee, and had a greater increase in knee varus alignment from baseline to 1-year follow-up. The progressors also had frontal plane hip and knee kinetics during baseline gait analysis that potentially increased medial knee joint loading. CONCLUSION The loss of cMF cartilage volume was highly variable and the median loss of cartilage was within the range previously reported. Seven of the 13 individuals did not have cMF cartilage volume loss greater than the standard error of measurement. Change in cartilage volume of the cMF may be influenced to a greater extent by personal factors than by completion of a therapeutic exercise program. Additional research is needed to decipher the interactions among therapeutic exercise and personal characteristics that impact knee cartilage loss.

Altered Gait Characteristics in Individuals With Knee Osteoarthritis and Self-Reported Knee Instability

STUDY DESIGN Experimental laboratory study. OBJECTIVE To characterize the differences in lower extremity gait biomechanics in individuals who have knee osteoarthritis (OA) with and without self-reported knee instability. BACKGROUND Individuals with knee OA who experience episodes of knee instability often report gait difficulties that interfere with their daily lives. A better understanding of the alterations in gait biomechanics may help to mitigate symptomatic knee instability in this patient population. METHODS Seventeen participants with knee OA and self-reported knee instability and 36 participants with knee OA and no self-reported knee instability underwent instrumented gait analysis on level ground. Knee-specific symptoms and functional limitations were assessed using the Western Ontario and McMaster Universities Osteoarthritis Index. RESULTS Knee instability was associated with greater odds of reporting moderate to severe gait-related pain (odds ratio = 6.0; 95% confidence interval: 1.2, 28.9) and moderate to severe difficulty when walking on flat surfaces (odds ratio = 10.7; 95% confidence interval: 1.7, 69.2). During early stance, the group with self-reported knee instability walked with a greater knee flexion excursion (P = .02) and a smaller lower extremity support moment (P<.01), due to reduced contributions from the hip extensors (P<.01) and ankle plantar flexors (P = .04). The group with self-reported knee instability also walked with a greater knee extensor contribution to the lower extremity support moment (P = .04) during the initial knee extension phase of gait compared to their counterparts with good knee stability. CONCLUSION These findings suggest that self-reported knee instability is associated with significant alterations in hip, knee, and ankle joint function during the stance phase of gait in individuals with knee OA.