THE STUDY OF THE EFFECT OF HIP ABDUCTOR STRENGTHENING EXERCISES ON BIOMECHANICS OF SUBJECTS WITH PATELLOFEMORAL PAIN SYNDROME
Desmond Y.R. Chong1, Xueli Wu2, Jason Y.M Choi3, Raye C.H Yeow2
1Singapore Institute of Technology, Singapore;
2National University of Singapore, Singapore;
3Changi General Hospital, Singapore
Patellofemoral Pain Syndrome (PFPS) is one of the most common knee joint disorders affecting physically active individuals, with higher incidences in young adults and adolescents. Symptoms include pain around and behind the kneecap exacerbated during daily activities such as stair ascend and descend. More recently, hip muscle weakness was identified in PFPS patients. Following which, hip abductor strengthening was suggested as a viable alternative to traditional conservative treatments. However, very few researchers have quantified the effects of hip muscle strengthening exercises. Thus, the aim of the study was to investigate the effects of hip-abductor strengthening on kinematics and muscle activities of PFPS subjects during stair ascend and descend. Fourteen participants (8 female, 6 male) with PFPS were recruited and placed on a 6-week hip-abductor strengthening programme. Peak hip adduction and internal rotation angles, peak knee valgus angle, gluteus medius strength, vastus lateralis (VL) and vastus medialis oblique (VMO) onset time difference, iliotibial band (ITB) flexibility (measured by Ober test) results as well as pain and functionality scores were assessed on initial evaluation and at post-intervention. Paired t-test was used to assess the outcome measures between baseline and post-intervention (p<=0.05). Pain, functionality, ITB flexibility and VL versus VMO onset time difference were significantly improved following the intervention. Gluteus medius muscle activity level was increased significantly. Peak hip adduction and knee valgus angles showed significant reduction from baseline, while no significant change was observed in the peak hip internal rotation angle post-intervention. In conclusion, the 6-week hipabductor strengthening exercise was effective in relieving knee pain and improving functionality in PFPS subjects. Simultaneously, an increase in gluteus medius strength and ITB flexibility, altered VLVMO onset time difference and a decrease in peak hip adduction and knee valgus angles were observed, leading to reduced lateral patella mal-tracking thus relieving knee pain.