Is the percutaneous myofascial lengthening of the hamstrings as effective and simple as open surgery?

Abstract

Medial hamstring fractional lengthening is commonly performed in children with cerebral palsy (CP). Percutaneous procedures are gaining more and more popularity even in the pediatric population with equivocal results. The purpose was to determine the efficacy and safety of percutaneous medial hamstring myofascial lengthening (PHL). This is a cross-over randomized controlled trial, including 31 consecutive knees from 18 patients with cerebral palsy (CP) scheduled for medial hamstring tenotomy in the setting of multilevel tendon lengthening procedures in a university hospital. Other concomitant lower extremity surgeries were not exclusionary. A first pediatric orthopedic surgeon executes the percutaneous medial hamstrings presumed myofascial lengthening (PHL) at one level as recently described in the literature. Another surgeon opens and extends the wound to explore what had been cut during the PHL, and completes fractional lengthening (OHL) of both semi-membranosus (SM) and semi-tendinosus (ST) when possible. Popliteal angle (PA) was assessed by a third surgeon immediately before PHL, after PHL, and then after OHL, using a goniometer, in a standardized reproducible manner. All 3 surgeons were blinded to the others’ findings. Primary endpoints included easiness to perform PHL, the percentage of tendon-fascia muscle portion sectioned percutaneously, and improvement of PA. Comparison between PA after PHL and OHL was done using a paired t -test with a 95% confidence interval. The first surgeon was at ease in palpating and identifying through the skin both medial hamstrings before PHL in 10 cases only. PHL led to undesirable cut of the semi-membranosus muscle fibers to more than 50% of the muscle section area in 30 cases ( P P = 0.38) nor with the extent of semi-tendinosus muscle divided ( P = 0.35). No major iatrogenic neurovascular injury was observed. This is the first prospective study concerning the anatomic effects of PHL. This quick procedure is often associated with difficulty to identify and evaluate what should be cut percutaneously, leading to abusive injury of the muscle itself. The gain in PA is statistically less following PHL than following OHL despite undesirable extensive muscle injury following PHL. This may be due to the multiple fascial cuts (fractional lengthening) usually performed in OHL.