Impact of Exercise Modality and Joint Angle on Patellar Tracking in Patients with Lateral Patellar Compression Syndrome: A Physiotherapy Perspective

Abstract

ABSTRACT

BACKGROUND: Lateral Patellar Compression Syndrome (LPCS) is a common cause of anterior knee pain, often linked to abnormal patellar tracking. Though both open and closed kinetic chain exercises are used in rehabilitation, evidence comparing their effects on patellar tracking across different knee flexion angles remains limited.

OBJECTIVE: To evaluate and compare the effects of open and closed chain exercises and varying knee joint positions on patellar tracking in patients with LPCS using computed tomography (CT) congruence angle measurement.

METHODS: A prospective, single-blinded, randomized controlled trial was conducted with 80 patients diagnosed with LPCS (60 females, 20 males; aged 18–45). CT scans were performed at 0°, 10°, 20°, 30°, and 40° of knee flexion in three muscle activation conditions: relaxed, open chain, and closed chain. The congruence angle was measured as an objective marker of patellar tracking. Open chain exercises included straight leg raise, short arc quadriceps, and knee extensions. Closed chain exercises included squats and leg press. The outcome was further supported using the Visual Analog Scale (VAS) for pain.

RESULTS: Patellar congruence significantly improved in the closed chain and relaxed conditions compared to the open chain condition at 0°, 10°, and 20° of flexion (p < 0.0001). Across all conditions, patellar tracking improved progressively from 0° to 40° of flexion. Closed chain exercises demonstrated better tracking patterns, especially in early flexion ranges, whereas open chain exercises were found more suitable after 30° of knee flexion. VAS scores showed statistically significant reductions in pain post-intervention.

CONCLUSION: Closed chain exercises produce more favourable patellar tracking during early knee flexion and may be prioritized in LPCS rehabilitation, especially in the initial stages. Open chain exercises can be introduced after 30° of flexion to minimize patellofemoral joint stress. Knee angle and type of exercise must be strategically selected to optimize outcomes in patellofemoral rehabilitation.

KEYWORDS: Patellofemoral Pain Syndrome, Open Chain Exercise, Closed Chain Exercise, Patellar Tracking, Vastus Medialis Oblique, Congruence Angle, Visual Analog Scale (VAS)