Aponeurotic release of semimembranosus: A technical note to increase correction gained with hamstring lengthening surgery in cerebral palsy.

Objective: The aim of this study was to determine the intraoperative corrective effect of the aponeurotic release of semimembranosus (SM) as a single procedure or an adjunct procedure to distal myotendinous release of semitendinosus (ST) and myofascial release of SM lengthening in the correction of knee flexion deformity in cerebral palsy (CP).
Methods: In this prospective study, 46 knees of 23 consecutive ambulatory patients (15 boys and 8 girls; mean age=8.33 years; age range=5-12 years) with spastic diplegic CP with a gross motor function classification system level (GMFCS) II or III were included. The patients were then divided into 2 groups. In group I, there were 10 patients (4 boys, 6 girls; mean age=8.6±2), and combined release of ST in the myotendinous junction and SM in the myofascial junction, followed by aponeurotic release of SM were carried out. In group II, there were 13 patients (2 girls, 11 boys; mean age=8±2.35), and aponeurotic release of SM was done first and followed by the combined release of ST in the distal myotendinous junction and the myofascial release of SM. Intraoperative popliteal angle (PA) measurements were recorded in each group.
Results: PA was reduced from 58.1°±7.6° (range=46°-75°) to 41.2°±8.8° (range=20°-54°) in group 1 and from 59.1°±11.3° (range=40°-87°) to 42.7°±10.8° (range=24°-64°) in group 2. No significant difference was observed between the groups in terms of reduction in PA (p=0.867). In group 1, adding the aponeurotic release of SM further reduced the PA to 31.7°± 8.5° (range=14°-47°) (p=0.002). In group 2, adding the myotendinous release of ST and myofascial release of SM further reduced the PA to 32.9°±7.2° (range=16°-44°) (p=0.004). There was no significant difference between the final PA values in the 2 groups (p=0.662). There was no difference in terms of early complications.
Conclusion: Aponeurotic release of SM is equally effective to reduce the intraoperative PA with combined myotendinous release of ST and myofascial release of SM. Combining all the 3 procedures provides a better correction without forceful manipulation or lengthening of the lateral hamstrings during the correction of knee flexion deformity in CP.