Static and dynamic abductor function are both associated with physical function 1 to 5 years after total hip arthroplasty.

BACKGROUND: A subset of total hip arthroplasty patients experience functional impairments past the first postoperative year. Poor hip abductor function is common before and in the early postoperative period. It is not known if abductor impairment is associated with long-term functional impairment. This study evaluated the relationships between static and dynamic abductor function and performance-based and self-reported function >1 year post-total hip arthroplasty. METHODS: Eighteen adults 1-5 years post-total hip arthroplasty participated. Static and dynamic abductor function were assessed through dynamometry and gait analysis, respectively. Subjects completed four physical performance tests and two self-report instruments. FINDINGS: Higher peak isometric abductor strength was associated with better performance-based function (P ≤ 0.001-0.030) and with self-reported function (P ≤ 0.001-0.012). Higher peak external adduction moment was associated with better results on 3 of 4 performance tests (P = 0.007-0.026). Together, static and dynamic abductor function predicted 35-77% of the variation in physical function. Abductor strength best predicted walking test results and self-reported function, while dynamic abductor function best predicted tests involving sit-to-stand INTERPRETATION: Static and dynamic abductor function were associated with physical function 1-5 years after total hip arthroplasty. These results support further investigation of interventions targeting abductor function for persons experiencing persistent impairments.

Inter-joint coordination of kinematics and kinetics before and after total hip arthroplasty compared to asymptomatic subjects.

While differences in joint kinematics and kinetics between control subjects and patients before and after total hip arthroplasty (THA) has often been studied, inter-joint coordination has not been fully characterized. We hypothesized that in patients undergoing THA, inter-joint coordination (i) is different from control subjects before surgery, (ii) changes from pre-operative to post-operative, and (iii) remains different from control subjects after surgery. Seventy-eight subjects underwent gait analysis before and ∼1 year after primary unilateral THA. 109 control subjects were age, sex, and BMI matched to the THA group. We selected a representative trial at each subjects' self-selected walking speed from a motion analysis data repository. To assess kinematic coordination, we constructed sagittal plane hip-knee angle cyclograms, and calculated total, stance, and swing phase plot area (deg2). To assess kinetic coordination, we calculated the support moment (MS, %wt ∗ ht), the time-integral of support moment (MS impulse, %wt ∗ ht ∗ t), and the relative contribution of each joint to MS impulse (%Hip, %Knee, %Ankle). We used t-tests to compare groups. Total and swing-phase cyclogram area was smaller preoperatively, but improved to control values after THA. Swing-phase area was smaller than control values after THA. MS impulse was larger in THA subjects than controls both before and after surgery. While, the relative contribution of the hip to MS impulse was not different from control values, the contributions of the knee and ankle were smaller. Inter-joint coordination, as measured by hip-knee angle cyclograms and MS impulse, may be used to distinguish differences in gait mechanics between osteoarthritis and THA. Future work focusing on coordination among joints may be needed to fully restore gait function.

An exercise trial targeting posterior shoulder strength in manual wheelchair users: pilot results and lessons learned.

PURPOSE: Because wheelchair users are unable to use standard fitness equipment such as treadmills and bikes, we developed an upper body rowing ergometer (UBRE) that can be retrofitted onto a standard stationary cycle and used to perform a rowing exercise. We validated a graded exercise testing protocol utilizing the UBRE and completed a 12-week pilot intervention to compare the training effects of the UBRE to a standard arm cycle ergometer (ACE) in manual wheelchair users. METHODS: Repeat graded exercise tests were compared on the two pieces of equipment. Twenty-seven manual wheelchair users participated in the intervention. Outcomes included pre- versus post-test change in shoulder pain, strength and cardiorespiratory fitness measures. RESULTS: Testing results obtained with the UBRE were comparable to those on the ACE. In the exercise intervention, most outcome measures did not change significantly, but individuals assigned to the UBRE were able to increase their peak exercise test power by 31 W and duration by 3.6 min. CONCLUSION: There is biomechanical reason to believe that rowing exercises may improve shoulder muscle balance in this population, which could reduce the risk of impingement. This may be of benefit to manual wheelchair users, who are at high risk for shoulder injury. Implications for Rehabilitation Regular exercise improves cardiorespiratory fitness and did not exacerbate shoulder pain in this group of manual wheelchair users. Exercises that target posterior shoulder muscle groups, such as rowing, may improve muscle balance and reduce the risk of shoulder impingement. Participation in exercise is hindered in this population by a high rate of secondary health conditions and difficulty accessing facilities and equipment.