Postoperative analgesia in TKA: ropivacaine continuous intraarticular infusion

Abstract

Background: Postoperative pain control is a challenge in patients undergoing TKA due to side effects and technical limitations of current analgesic approaches. Local anesthetic infiltration through continuous infusion pumps has been shown to reduce postoperative pain in previous studies.

Questions/purposes: We assessed the effectiveness of intraarticular ropivacaine infusions in reducing pain and postoperative opioid use after TKA and determined whether such infusions accelerate functional recovery of the patient and reduce length of hospital stay.

Methods: In a randomized, prospective, double-blind study, two groups were assigned: Group A (n = 25) underwent continuous intraarticular infusion with 300 mL ropivacaine 0.2% at a speed of 5 mL/hour through an elastomeric infusion pump and Group B (n = 25) had an elastomeric pump insertion with 300 mL saline solution at an infusion speed of 5 mL/hour. All patients had the same prosthesis model implanted. Parameters analyzed over the first 3 days, at discharge, and 1 month later included postoperative pain, joint function, opioid use, and length of hospital stay.

Results: All patients in Group A showed a decrease in pain intensity measured by a visual analog scale and opioid use in the first 3 days. Mean length of hospital stay was also reduced in Group A (5.72 days) compared to Group B (7.32 days). There were no device-related complications.

Conclusions: Use of an infusion pump is effective in treating pain after TKA, reducing postoperative pain and opioid use. It also improves immediate functionality and patient comfort, reducing the mean length of hospital stay, without increasing the risk of complications.

Level of evidence: Level I, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Fig. 1A–B

Photographs show the continuous infusion system used in the study: (A) the intraarticular catheter and the trochar used in its insertion and (B) the elastomeric pump filled with ropivacaine.

Fig. 2A–B

(A) Definitive placement of the intraarticular catheter in the upper knee area to facilitate the filling of the whole articular cavity is shown. (B) The ropivacaine infusion catheter with drain is shown.

Fig. 3

A graph shows mean VAS scores for each group in the preoperative period (PRE), on Postoperative Days 1, 2, and 3, at discharge (DISCH), and at 1 month after surgery. The baseline situation was similar between groups, yet during the first 3 postoperative days, pain reduction occurred, which leveled out at discharge and at 1 month.

Fig. 4

A graph shows the percentage of patients requiring opioid use as supplementary analgesia to control pain during the first 3 postoperative days in Groups A and B. There was a reduction (p < 0.004) in the number of patients who required opioids for pain control during the first 3 days.

Fig. 5

In both groups, the patients requiring opioid treatment showed a high percentage of side effects.

Fig. 6

A graph shows ROM in Groups A and B on Postoperative Days 1, 2, and 3, at discharge (DISCH), and at 1 month. In the postoperative period, the two groups were similar. Improvements in ROM leveled out 1 month after surgery for both groups.