Comparative analysis of isokinetic parameters in individuals with and without chondromalacia patellae.

Introduction: Chondromalacia patella (CMP) is characterized by cartilage degeneration, affects young adults, more women (2:1) and is responsible for 75% of knee pain complaints in the active population. The etiology is multifactorial and may be related to extrinsic factors (trauma and burden) and intrinsic factors (patellar malalignment and quadriceps weakness). Isokinetic dynamometry (ID) can aid in the detection of the causal factors of knee pain related to CMP.

Objectives: To evaluate and compare the parameters of the ID of individuals with and without CMP and correlate them with the clinical aspects of individuals with CMP.

Methods: This is a study retrospective that analyzed ID of the knee flexors and extensors, performed between 2013 and 2019 in the isokinetic dynamometry sector of the hospital. Six hundred ninety dynamometers tests were included, both sexes, aged between 14-59 years, divided into Chondromalacia Group (342) tests and Control Group (348) tests. All performed ID in concentric mode for knee extension and flexion, with five maximum repetitions at an angular speed of 60º/s and 180º/s and 20 repetitions at an angular speed of 300º/s, with 30-second intervals between each. After completing the test, the patient points out a number from 0 - 10 on the visual analog scale, regarding the presence and intensity of pain during and after the isokinetic assessment.

Results: The groups similar distribution from sex (P=0.071); age (P=0.99), but were different about pain (P<0.001). CMP had greater levels of pain. In most of the muscle parameters of the extensors and flexors at 60°/s were lower in the CMP Group (P<0.001).

Conclusion: The main predictor of chondromalacia is pain. The greater coeffcient of variability and time to reach peak torque on the involved side, the average power and morphology of the extensor curve can also be predictor of chondromalacia.

Level of evidence: III.