EFFECTS OF OPEN CHAIN, CLOSED CHAIN AND COMBINED EXERCISES ON PAIN INTENSITY AND QUADRICEPS MUSCLE STRENGTH IN PATIENTS WITH ANTERIOR KNEE PAIN: A RANDOMIZED CONTROLLED TRIAL

Abstract

Background: Anterior knee pain (AKP) is a very prevalent musculoskeletal problem causing significant functional impairment in individuals who are physically active. Although exercise therapy is a well established as primary treatment, comparative effectiveness of open kinetic chain (OKC) exercises, closed kinetic chain (CKC) exercises and combined OKC+CKC exercise protocols remains under studied. No randomized controlled trial has simultaneously compared these three approaches in patients with acute AKP.

Objective: To compare effects of OKC, CKC and combined OKC+CKC exercise protocols on pain intensity and quadriceps muscle strength after four weeks of intervention.

Methods: A three-arm, parallel group randomized controlled trial enrolled 96 participants (aged 18-40 years) with acute AKP. Participants were randomized to Group A (OKC exercises, n = 32), Group B (CKC exercises, n = 32) and Group C (combined OKC+CKC, n = 32). All groups received standardized conventional physical therapy for anterior knee pain. Interventional exercises were performed three days per week at a dosage of four sets of 12 repetitions for four weeks. General Linear Model (GLM) repeated measures ANOVA with Bonferroni post hoc corrections and intention to treat (ITT) analysis were applied.

Results: Significant Time × Group interactions were observed for NPRS (F (2, 93) = 37.880, p < .001) and quadriceps strength (F (2, 93) = 2674.875, p < .001). Group C demonstrated greatest pain reduction (mean NPRS decrease: 4.59 points; 71.0% from baseline) and quadriceps strength gains (mean increase: +9.22 kg; 63.9%). Post hoc analysis confirmed Group C was significantly superior to both Groups A and B (p < 0.001). No significant difference was found between Groups A and B for either outcome.

Conclusion: Combined OKC and CKC exercises generated superior improvements in pain intensity and quadriceps muscle strength compared to single modality intervention of OKC or CKC in acute AKP.