Planovalgus foot deformity in hemiplegic children: A clinical and radiological evaluation after botulinum toxin injection in peroneus longus

Objective Miller [1] describes the natural history of planovalgus in cerebral palsy (CP) as the common foot deformity in CP children. He emphasizes that the causes are an early muscle imbalance by overactivity of peroneal muscles and the primary pathology begins when the talus head is uncovered medially, associated with a talus equinus in X-rays and a subluxated talus head causing a midfoot planus. In hemiplegic children( [2] . It suggests that PL could be a therapeutic target by botulinum toxin (BoNT-A) injections. This hypothesis is tested in a retrospective study. The clinical and radiological efficiency is assessed. Material/patient and methods Sixteen hemiplegic (3.25 years ± 1.5), GMFCS 1 or 2, with a planovalgus foot deformity during the stance phase and, during SW, a dynamic equinus with hindfoot valgus and a premature overactivity of PL were treated by a BoNT-A injection (Dysport ® ,Ipsen) into PL. Radiological foot parameters measured forefoot pronation, midfoot planus, valgus and equinus of hindfoot. These parameters are validated in the healthy and hemiplegic children. A paired t -test compared for each angle the pre and post-toxin measurement. Results The parameters described between pre-toxin vs normal data: calcaneal-pitch (8°vs 17° P P  0.05),lateral talo-first metatarsal angle (29°vs 13° P P  0.001). There was a non-significative difference, between pre vs post-toxin, for the calcaneal-pitch angle (7°vs 9°) and the anteroposterior ankle angle(14°vs 15° P P P P Discussion Before injections, the radios showed a hindfoot valgus, a dorsalflexed calcaneus with midfoot planus and a forefoot pronation. After injections, midfoot planus is reduced by the decrease of talus subluxation and there was not forefoot pronation. Injections into PL seemed to have a therapeutic actions on fore and midfoot that improved clinically the hindfoot valgus but without action on the dorsalflexed of calcaneus depending on the gastrocsoleus complex. PL could be an early therapeutic target for BoNT-A in planovalgus.