Biomechanics of the ankle

Comparison of ground reaction forces and antagonist muscle coactivation during stair walking with ageing.

We report the clinical and radiological outcome of total ankle replacement performed in conjunction with hindfoot fusion or in isolation. Between May 2003 and June 2008, 60 ankles were treated with total ankle replacement with either subtalar or triple fusion, and the results were compared with a control group of 288 ankles treated with total ankle replacement alone.After the mean follow-up of 39.5 months (12 to 73), the ankles with hindfoot fusion showed significant improvement in the mean visual analogue score for pain (p < 0.001), the mean American Orthopaedic Foot and Ankle Society score (p < 0.001), and the mean of a modified version of this score (p < 0.001). The mean visual analogue pain score (p = 0.304) and mean modified American Orthopaedic Foot and Ankle Society score (p = 0.119) were not significantly different between the hindfoot fusion and the control groups. However, the hindfoot fusion group had a significantly lower mean range of movement (p = 0.009) and a higher rate of posterior focal ...

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Total ankle replacement in association with hindfoot fusion OUTCOME AND COMPLICATIONS

The human ankle joint complex plays a fundamental role in gait and other activities of daily living. At the same time, it is a very complicated anatomical system but the large literature of experimental and modelling studies has not fully described the coupled joint motion, position and orientation of the joint axis of rotation, stress and strain in the ligaments and their role in guiding and stabilizing joint motion, conformity and congruence of the articular surfaces, patterns of contact at the articular surfaces, patterns of rolling and sliding at the joint surfaces, and muscle lever arm lengths. The present review article addresses these issues as described in the literature, reporting the most recent relevant findings.

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Biomechanics of the natural, arthritic, and replaced human ankle joint

Purpose: Knee osteoarthritis (OA) is one of the most prevalent chronic lower extremity diseases, causing profound limitation of movement and ability to perform activities of daily living. The purpose of this study was to compare various hip, knee, and ankle joint kinematic variables between knee OA subjects and matched healthy controls during stair ascent and descent.

Methods: Eighteen subjects with knee OA (age = 60.2 ± 9.9 yr, mass = 90.3 ± 16.7 kg, height = 168.4 ± 9.9 cm) and 18 healthy matched controls (age = 60.3 ± 10.7 yr, mass = 81.1 ± 21.2 kg, height = 168.3 ± 11.9 cm) participated in the study. Subjects performed five ascending and descending trials on a custom-built staircase while their motion was captured three-dimensionally using an eight-camera optical video motion capture system.

Results: Significant group × direction interactions were found for average hip flexion angle at foot strike (P = 0.04), for average ankle adduction angle at foot strike (P = 0.01), and for peak ankle dorsiflexion angle during support (P = 0.05) and swing (P = 0.01). Specifically, knee OA and control subjects demonstrated greater hip flexion angle at foot strike and ankle dorsiflexion angle during swing but showed smaller ankle dorsiflexion angle during support during stair ascent compared with descent. Furthermore, compared with controls, knee OA patients demonstrated greater hip abduction at foot strike (-3.1° ± 3.9°) and smaller peak knee flexion during support (60.4° ± 5.0°) and swing (86.7° ± 5.4°). Time of peak hip abduction (34.2% ± 7.1%), hip flexion (7.0% ± 12.3%), knee flexion (69.8% ± 4.6%), dorsiflexion (51.4% ± 2.9%), and ankle adduction (37.3% ± 20.8%) during support occurred later in the gait cycle for knee OA patients.

Conclusions: These data demonstrate that knee OA directly influences specific knee joint kinematics and induces kinematic alterations at the hip and ankle perhaps to compensate for the existing knee joint pathology

Chii Jen Lin

Papers

Lower extremity kinematics and kinetics during level walking and stair climbing in subjects with triple arthrodesis or subtalar fusion