Hamstrings Dysfunction in Children with Spastic Cerebral Palsy: Can Muscle Modeling Provide Meaningful Information about Ambulatory Mobility?

Background/Purpose: Judging muscle functioning is vital when treating patients with spastic cerebral palsy [SCP]. Yet, in particular the role of biarticular muscles like the medial hamstrings is subject of controversy. By using motion capturing and musculoskeletal models, muscle-tendon length can be estimated. This approach was recently proposed for indicating soft-tissue surgeries or neurosurgeries. We tested the relationship between clinical scales of hamstrings dysfunction, muscle modeling data, and mobility.

Methods: Fifty-four ambulatory patients (N = 17/37 uni-/bilateral SCP, age: 8.8 ± 4.7 years) underwent a 3D gait analysis. All were also manually examined for knee flexor strength, popliteal angles, and muscle tone (modified Ashworth scale). MobQues47 questionnaires assessed the caregiver-reported mobility indoors and outdoors. Concerning walking, we calculated the medial hamstrings length and excursion. Regression analysis was done to predict mobility using clinical ratings and muscle parameters from 3D gait analysis.

Results: Regarding clinical ratings, only the knee flexor strength was significantly related to mobility (r = 0.53–0.55, p < 0.01). Modeled hamstrings length was mildly related (r = 0.30, p < 0.05), while their excursion during swing phase had the strongest relationship with mobility (r = 0.69–0.70, p < 0.01). During multiple regression, only the calculated muscle excursion remained in the prediction.

Conclusion: Clinical judgment of hamstrings shortness or tone may be of limited value for ambulatory mobility. As previously suggested, in particular weakness and decreased muscle excursion could be decisive for mobility and thus needs to be addressed during therapy. In future, electromyography and motion capturing may be combined to also objectively sense spasticity features, such as muscle stretch velocity and hyperexcitability.

Publication History

Article published online:
28 October 2021