Intra-articular ketamine for pain control following arthroscopic knee surgery

In an attempt to demonstrate the peripheral effect of ketamine on the synovia of knee joint and to smoothen the recovery from arthroscopic knee surgery, this study was designed to evaluate the analgesic effect of intra-articular ketamine injection after knee arthroscopy.

In a double blind randomized study, 60 patients were assigned to three groups. Group A patients received saline 5 mL intra-articularly after closure of the surgical wound to serve as control; group B patients received ketamine 0.5 mg/kg of body weight intra-muscularly to rule out the systemic effect and group C patients received ketamine 0.5 mg/kg of body weight diluted with saline up to 5 mL intra-articularly. After surgery, patients were evaluated for pain with visual analogue scale (VAS 0 to 10) for 24 h with the operated leg in the position of extension rest and active flexion of the knee joint to 60 degree angle. Rescue pethidine (1 mg/kg of body weight) was given intra-muscularly for pain relief at request every 4 h postoperatively if necessary. The time to first rescue analgesic request was recorded, and the total doses of pethidine were calculated.

The results showed no difference in the VAS pain scores at rest and during active motion in the range of 60 degree among three groups during a 24 h observation.

Ketamine had been reported to have peripheral analgesic effects with variable duration on measurements of pain and hyperalgesia. However, in the present study, we failed to demonstrate that ketamine could provide a clinically relevant peripheral analgesic effect for postoperative arthroscopic pain.