gms | German Medical Science

Objectives: We have recently established a modified surgical anchor refixation for repair of proximal hamstring tendon rupture aiming at refixing the hamstring tendons proximal and lateral of their anatomical origin to increase muscle pretension and moving the insertion site of the tendons away from the region loaded while sitting. The purpose of this follow-up study was to determine if local tenderness or side-to-side differences in gait kinematics and kinetics and/or muscle activity are present after acute proximal hamstring tendon rupture treated with modified surgical anchor refixation.

Methods: Twelve patients completed gait analysis (median, interquartile range) 49.5 (30.8-62.0) months after surgery (7 female, 5 male; age, 63.2 (58.9-68.2) years; body mass index, 28.7 (27.6-30.2) kg/m²). Local tenderness was assessed by palpation of the ischial tuberosity. Bilateral kinematic and kinetic data and activity of eight leg muscles (glutaeus maximus and medius, vastus medialis and lateralis, semitendinosus, biceps femoris, tibialis anterior, gastrocnemius medialis) were collected during overground walking at preferred walking speed using 10 high-speed cameras, two force plates and surface electromyography (EMG). Joint angles and external moments were computed using the Plug In Gait model. Joint moments were normalized to body weight and muscle activity to maximum voluntary contraction. Kinematic, kinetic and EMG trajectories were time normalized to gait cycle. Biomechanical parameters were compared between the affected and unaffected sides using statistical parametric mapping (SPM) with paired sample t tests (P<0.05).

Results and conclusion: Only one patient (8.3%) indicated local tenderness of the injured side. Patients walked at median speed of 1.35 (1.09-1.39) m/s and a median cadence of 110 (107-114) steps/minute. Spatiotemporal parameters did not differ between sides (Table 1 [Tab. 1]). Although the knee flexion moment during the first half of stance tended to be greater, the knee extension moment during the second half of stance lower and the biceps femoris muscle more activated during most of the gait cycle on the affected side compared to the unaffected side, none of these differences were significant (Figure 1 [Fig. 1]). All other joint angles and moments and muscle activities were comparable between sides (P>0.05).

Comparable gait biomechanics between limbs supports the theory that normal gait function is restored using this modified surgical technique while avoiding commonly reported local tenderness. The results emphasize the importance of not only considering patient reported outcomes but also biomechanical function when evaluating novel surgical techniques.