Gait biomechanics after total hip arthroplasty: using statistical parametric mapping to identify differences between various surgical approaches

Biomechanical studies have tried to assess the impact of the surgical approach on gait characteristics and recovery after total hip arthroplasty (THA). Some studies which used discrete analyses have shown that some surgical approaches provide better hip joint function after one year post-surgery, but several studies did not find any differences. The goal of this study was to compare hip biomechanics during gait using statistical parametric mapping (SPM) in patients who underwent THA with either a lateral (LAT), anterior (ANT), or posterior (POS) approach. Forty-five patients underwent unilateral THA with either a LAT, ANT, or approach, and were compared with 15 healthy controls (CTRL). All patients underwent biomechanical gait analysis approximately 9 months following surgery. Hip biomechanics were compared between groups throughout the entire gait cycle using a One-Way ANOVA SPM. Alpha was set to 0.05 and Bonferroni post hoc comparisons were completed. The POS group had a significantly lower hip flexion moment just prior to toe-off compared to the ANT and CTRL groups. The ANT group had significantly lower hip abduction moment for most of the stance phase compared to the LAT and CTRL groups. The POS group had a significantly lower hip abduction moment compared to the LAT and CTRL groups. These findings tend to contradict existing literature. Future studies should complete both pre- and post-operative assessments with a larger cohort in each group, as well as standardize the implants as much as possible to determine if observed differences are due to the approach and no other factors.
Listed In: Biomechanics, Orthopedic Research

Effect of Transcutaneous Electrical Nerve Stimulation on Gait Kinematics in Subjects with Anterior Knee Pain

Knee pain is 1 of 5 leading causes of disability by altering lower-extremity muscle function and gait mechanics. While transcutaneous electrical nerve stimulation (TENS) mitigates deficits of muscle function due to pain, it is unclear whether TENS improves gait mechanics. Each of 15 participant (24±3yrs, 71±12kg, 178±7cm) was assigned to the TENS or matched placebo group (23±2yrs, 72±14kg, 177±9cm). Participants underwent 3 different experimental saline infusion sessions (hypertonic, isotonic, control) in a counterbalanced order, separated by 48-h. Hypertonic (5% NaCl) or isotonic (0.9% NaCl) saline was infused into the infrapatellar fat pad for 50-min. No infusion was administered to the control session. Participants and investigators were blinded to the saline solution. A 20-min TENS or placebo treatment was administered, which was blinded to participants. Gait kinematic data were collected using the high-speed video (240 Hz) and force-sending tandem treadmill (1200 Hz) at each time interval (baseline, infusion, treatment, post-treatment). Functional ANOVA (α=0.05) were used to evaluate difference between 2 groups (TENS, placebo) over time. Pairwise comparison functions with 95% confidence interval were plotted to determine specific difference. Hypertonic saline infusion (pain) resulted in increased (1) ankle dorsiflexion (38-75% of stance), (2) knee valgus (20-40%), (3) knee flexion (40-90%), (4) hip adduction (72-100%), (5) hip flexion (50-90%). However, there was no group x time interaction for all kinematics. Altered gait strategies due to pain may play a role in long-term compensation that could have consequences for the joint. TENS treatment, however, did not acutely reduce the deficits in aforementioned kinematic variables.

Listed In: Biomechanics, Gait, Neuroscience, Physical Therapy