Bilateral Hidden Isokinetic Quadriceps Performance before and after MPFL Reconstruction in Pediatric Patients

Abstract

We perform prospective study to evaluate the isokinetic performance of quadriceps before and 1 year after medial patella-femoral ligament (MPFL) reconstruction with the adductor magnus tendon in the case of recurrent patellar dislocation. The present study is the first to describe the isokinetic function of the quadriceps of the involved and uninvolved extremity, in such a wide range. The MPFL is a crucial passive stabilizer of patella and, along with the conditions of the anatomical shape of the femoral-patellar joint and the function of quadriceps, influences the overall patellar stability. However, only a few studies have examined indirectly or directly the function of quadriceps. A total of 27 patients (average age at surgery was 15.8 years) with recurrent monolateral patellar dislocation were treated with MPFL reconstruction using the adductor magnus tendon. In the study group, healthy and operated quadriceps were evaluated for the following parameters at the velocities of 60 and 180 deg/s before surgery and in the follow-up examination: peak torque, peak torque to body weight, time to peak torque, peak torque angle, torque in 30 degree of the knee flexion (TQ 30 degree), and the torque in the first 180 milliseconds (TQ 180). Preoperative patellar instability and its normalization after MPFL reconstruction have no impact on the isokinetic quadriceps index value which depends on the time and degree of inactivity as well as implementation of appropriate physiotherapy. The increase in the quadriceps muscle strength of a healthy limb is responsible for the persistence of muscle isokinetic imbalance after MPFL reconstruction in pediatric patients. This is a level 2b study.

A clinical, radiological and isokinetic evaluation in patients with recurrent patellar dislocation undergoing MPFL reconstruction according to Avikainen: a prospective study evaluating early degenerative changes after a minimum 10-year follow-up period

“…Interestingly, no further increase in flexor strength was observed after the three-year follow-up examination. It is difficult to provide a clear reason for this, but the data could confirm that patients with patellar instability demonstrate constitutional weakening of the knee flexors: we would expect flexor strength to gradually increase with quadriceps strength [1,12].…”

“…Few studies have examined the long-term results of treating recurrent patellar dislocation in children and adolescents, and none include any long-term assessment of early degenerative changes or the objective performance of extensor apparatus. In addition to patella stability, long-term postoperative degenerative changes may have a significant influence on knee function, patient satisfaction and the final treatment outcome, and the knee flexors performance may display their constitutional weakness in patients with recurrent patellar dislocation, as discussed in theliterature [1].…”