Objective: Exogenous hyaluronic acid (HA) acts as a lubricant and shock absorber, and is considered to have many other beneficial effects in the joint. Several studies have shown that HA is able to provide pain relief and promote the synthesis of endogenous HA and protect the cartilage and synovia by covering joint surfaces. The objective of this study is to investigate wheter an isotonic solution of hyaluronan reduces post-arthroscopic symptoms in the knee such as joint pain, swelling and impairment of function when injected into the joint following arthroscopic surgery.

Material and Methods: A total of 93 patients (66 men, 27 women) were assessed in a multicentre, controlled study conducted by several investigators from different orthopedic surgery departments in Spain. All investigators were highly skilled in arthroscopy. Patients were allocated into two groups, control group (45 patients) or treatment group (48 patients). The treatment group received an injection of 10ml of isotonyc solution of hyaluronan (ISH) 0.5% with a physiological pH value at the end of the knee arthroscopy after final lavage with normal irrigating solution. Untreated patients underwent standard arthroscopic surgery (meniscectomy or articular lavage) and did not receive any further treatment on completion of the procedure. Pain in patientes were assessed using a 100mm visual analog scale (VAS). Between-group comparative analyses were performed before surgery and 1 and 4 weeks after surgery using a Mann-Whitney U-test.

Results: One week after surgery, a significant reduction in pain (up to 17%) was observed for patientes treated versus control patients (p< 0.01). This improvement was maintained until week 4, although the difference between control group and treated group decreased over time. The area under the curve of VAS was 39% lower for treated patients versus untreated patients. On comparing both groups, there was a significant 8% difference in the reduction of other functional symptoms at 1 week after surgery but no difference at 4 weeks after surgery. No adverse events were reported.

Conclusions: The results show that there were was a significant decrease in pain in the first week after surgery, accompanied by a significant reduction in sum of symptom scores. These results suggest that ISH accelerates post-arthroscopy recovery during this important period by reducing pain and discomfort, and increasing the mobility of the affected knee.