Lower Extremity Biomechanics During Single Leg Drop Landings in Individuals with Patellofemoral Pain

Patellofemoral joint pain (PFP) is one of the most common afflictions of the active population. While etiological factors encompassing the entire lower extremity have been associated with PFP, participation in athletic activities while fatigued may further influence abnormal biomechanics in individuals with this condition. The aim of Project I was to investigate the lower extremity (LE) biomechanics during a single leg(SL) drop landing in individuals with and without PFP. Project II aimed to investigate the LE biomechanics of individuals with PFP during a SL drop landing pre and post an aerobic exercise protocol. Project 111 investigated the LE biomechanics of individuals with PFP during a SL drop landing pre and post an isolated hip abduction fatigue protocol. Twenty-two physically active individuals(11 PFP, 11 control) participated in Project I. Participants performed SL drop landings from three heights(20, 30, and 40cm). Eleven physically active individuals with PFP participated in Project II. Participants performed SL drop landings at three heights, pre and post an aerobic exercise protocol. Twenty physically active individuals with PFP participated in Project III. Participants in this study performed SL drop landings from three heights pre and post an isolated hip abduction fatigue protocol. Three-dimensional kinematics and kinetics were recorded and assessed using 2x3 repeated measure ANOVAs(P≤0.05) in all projects. For Project I, the results demonstrated that individuals with PFP landed with less knee flexion(-48.43±7.16°) compared to the control group(-56.43±7.16°)(P=0.017) at the instance of maximum knee flexion(MaxKF) suggests that the PFP group employ a stiffer landing pattern and may not attenuate the forces imposed on the LE as well as a healthy individual. In Project II, an increase in knee flexion at MaxKF was demonstrated in the post fatigue landings(-50.78±6.96°) compared to the pre fatigue landings(- 48.43±6.37°)(P=0.49) suggesting that individuals with PFP may demonstrate a decreased ability to control the forces of a SL landing due to fatigue. Project III, a decrease in hip external rotation moment was present following the fatigue protocol(Pre:0.25±0.12Nm, Post;0.28±0.10Nm;P=0.047) at MaxKF despite this result, project III does not support a significant link between altered LE biomechanics during SL landings following an isolated hip abduction fatigue protocol

Weight-Bearing Dorsiflexion Range of Motion and Landing Biomechanics in Individuals With Chronic Ankle Instablity

Context: People with chronic ankle instability (CAI) exhibit less weight-bearing dorsiflexion range of motion (ROM) and less knee flexion during landing than people with stable ankles. Examining the relationship between dorsiflexion ROM and landing biomechanics may identify a modifiable factor associated with altered kinematics and kinetics during landing tasks. Objective: To examine the relationship between weight-bearing dorsiflexion ROM and single-legged landing biomechanics in persons with CAI. Design: Cross-sectional study. Setting: Laboratory. Patients or Other Participants: Fifteen physically active persons with CAI (5 men, 10 women; age = 21.9 ± 2.1 years, height = 168.7 ± 9.0 cm, mass = 69.4 ± 13.3 kg) participated. Intervention(s): Participants performed dorsiflexion ROM and single-legged landings from a 40-cm height. Sagittal-plane kinematics of the lower extremity and ground reaction forces (GRFs) were captured during landing. Main Outcome Measure(s): Static dorsiflexion was measured using the weight-bearing–lunge test. Kinematics of the ankle, knee, and hip were observed at initial contact, maximum angle, and sagittal displacement. Sagittal displacements of the ankle, knee, and hip were summed to examine overall sagittal displacement. Kinetic variables were maximum posterior and vertical GRFs normalized to body weight. We used Pearson product moment correlations to evaluate the relationships between dorsiflexion ROM and landing biomechanics. Correlations (r) were interpreted as weak (0.00–0.40), moderate (0.41–0.69), or strong (0.70–1.00). The coefficient of determination (r2) was used to determine the amount of explained variance among variables. Results: Static dorsiflexion ROM was moderately correlated with maximum dorsiflexion (r = 0.49, r2 = 0.24), ankle displacement (r = 0.47, r2 = 0.22), and total displacement (r = 0.67, r2 = 0.45) during landing. Dorsiflexion ROM measured statically and during landing demonstrated moderate to strong correlations with maximum knee (r = 0.69–0.74, r2 = 0.47–0.55) and hip (r = 0.50–0.64, r2 = 0.25–0.40) flexion, hip (r = 0.53–0.55, r2 = 0.28–0.30) and knee (r = 0.53–0.70, r2 = 0.28–0.49) displacement, and vertical GRF (−0.47– −0.50, r2 = 0.22–0.25). Conclusions: Dorsiflexion ROM was moderately to strongly related to sagittal-plane kinematics and maximum vertical GRF during single-legged landing in persons with CAI. Persons with less dorsiflexion ROM demonstrated a more erect landing posture and greater GRF