Prospective, Randomized, Double Blind Evaluation of the Efficacy of a Single Dose Hyaluronic Acid for the Treatment of Patellofemoral Chondromalacia

OBJECTIVES: Introduction: Patellofemoral pain is common and is often diagnosed as chondromalacia patella in the absence of radiographic evidence of osteoarthritis. Chondromalacia patella is often painful and debilitating, affecting patients’ function, activity level and quality of life. Non-operative management is limited and focuses on physical therapy and modalities. Hyaluronic acid (HA) is an injectable device that has been used for the treatment of knee osteoarthritis. We hypothesize that a single injection of HA will reduce pain, improve function and improve muscle strength in patients who have previously failed conservative management. METHODS: Methods: This was a prospective, randomized, double-blind, sham-controlled, parallel group clinical trial to compare outcomes for 6-months after a single injection of HA (Synvisc One) in the knees of patients with a diagnosis of chondromalacia patella. A total of 86 patients with a clinical diagnosis of chondromalacia (65F/21 M, 27.0±7.7years, 168.6±8.9 cm, 74.6±17.0 kg, BMI 26.0±5.2) including no radiographic evidence of tibiofemoral or patellofemoral osteoarthritis were recruited and enrolled in this study. All patients failed at least 1 month of conservative management including a program of therapeutic quadriceps strengthening exercises under a physical therapist’s direction. Patients were evaluated by blinded observers. Outcome assessments included patellofemoral pain assessment using a visual analog scale during a single leg squat, knee osteoarthritis outcome score (KOOS), Tegner activity rating and normalized isometric knee extension strength. After baseline measurements, patients were randomly allocated to either 6 cc of HA or a sham injection (needle stick) and visually shielded during injection for blinding. All patients were prescribed an additional home exercise program including lower extremity strengthening and flexibility exercises and followed at 1, 3 and 6 months. Group assignment was revealed to the patients after the 6 month outcome assessment and crossover treatment offered to patients receiving the sham injection who were still symptomatic. Repeated measures ANOVA was used to compare outcomes between groups and across time. RESULTS: Results: 45 patients were randomized to HA injection, 41 to sham, and 5 patients were lost to follow up (93% follow up rate). Patients in both groups experienced a significant reduction in visual analog pain ratings and significant increases in all domains of the KOOS at the 6 months compared to baseline measurement (P<0.05); however, there was no significant difference between groups. There were no differences observed over time or between groups for normalized knee extension strength or Tegner activity rating (P<0.05). CONCLUSION: Conclusion: We observed improvements in patient reported pain and function with no change in quadriceps strength or activity rating. HA injections did not have an effect at 6 months after injection. HA injection had no effect on pain or functional outcomes in patients with a clinical diagnosis of chondromalacia patella.