Abstract
Background: Patellar tendon advancement (PTA) is performed for the treatment of crouch gait in patients with cerebral palsy (CP). In this study, we aimed to determine the influence of PTA in the context of single-event multilevel surgery (SEMLS) on knee joint moment and muscle forces through musculoskeletal modeling; Methods: Gait data of children with CP and crouch gait were retrospectively analyzed. Patients were included if they had a SEMLS with a PTA (PTA group, n = 18) and a SEMLS without a PTA (NoPTA group, n = 18). A musculoskeletal model was used to calculate the pre- and postoperative knee joint moments and muscle forces; Results: Knee extensor moment increased in the PTA group postoperatively (p = 0.016), but there was no statistically significant change in the NoPTA group (p > 0.05). The quadriceps muscle forces increased for the PTA group (p = 0.034), while there was no difference in the NoPTA group (p > 0.05). The hamstring muscle forces increased in the PTA group (p = 0.039), while there was no difference in the NoPTA group (p > 0.05); Conclusions: PTA was found to be an effective surgery for the treatment of crouch gait. It contributes to improving knee extensor moment, decreasing knee flexor moment, and enhancing the quadriceps and hamstring muscle forces postoperatively.
Highlights
Patella alta, a superiorly displaced patella, is often observed and nearly universal in patients with cerebral palsy (CP) and crouch gait [1,2,3]
Boyer et al showed that patients subjected to distal femoral extension osteotomy (DFEO) + Patellar tendon advancement (PTA) had higher peak knee extensor moment than those who were not managed with DFEO + PTA [8]
Magnitudes of the knee joint moments were normalized to the mass of each patient
Summary
A superiorly displaced patella, is often observed and nearly universal in patients with cerebral palsy (CP) and crouch gait [1,2,3]. Patellar tendon advancement (PTA) is generally added to the surgery design of the patients with CP and crouch gait because of their knee flexion deficits [1,5,7]. PTA, performed by patellar tendon shortening or distal advancement of the tibial tuberosity, corrects quadriceps insufficiency to enhance knee extension moment during gait by improving the quadriceps moment arm. Several studies investigated the postoperative results of the PTA using gait analysis [1,8,9,10,11] All these studies have shown that joint kinematics, especially knee joint kinematics, improved postoperatively (please see Figure A1). Brandon et al reported that knee flexion moment significantly increased with the proportion of severity of crouch gait [12]. Hyer et al reported that DFEO with patellar tendon imbrication significantly decreased knee moment in late stance [13]
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