Periarticular injection in knee arthroplasty improves quadriceps function

Abstract

Background: The postoperative analgesic potential of periarticular anesthetic infiltration (PAI) after TKA is unclear as are the complications of continuous femoral nerve block on quadriceps function.

Questions/purposes: We asked (1) whether PAI provides equal or improved postoperative pain control in comparison to a femoral nerve block in patients who have undergone TKA; and (2) if so, whether PAI improves early postoperative quadriceps control and facilitates rehabilitation.

Methods: We randomized 60 patients to receive either PAI or femoral nerve block. During the first 5 days after TKA, we compared narcotic consumption, pain control, quadriceps function, walking distance, knee ROM, capacity to perform a straight leg raise, and active knee extension. Medication-related side effects, complications, operating room time, and hospitalization duration were compared.

Results: Opioid consumption was lower in the PAI group during the first 8 postoperative hours (12.5 mg versus 18.7 mg morphine), as was reported pain at rest (1.7 versus 3.5 on a 10-point VAS). Thereafter, narcotic consumption and reported pain were similar up to 120 hours. More subjects in the femoral nerve block group experienced quadriceps motor block (37% versus 0% in the PAI group). On Days 1 to 3, subjects in the PAI group experienced better capacity to perform the straight leg raise, active knee extension, and had longer walking distances.

Conclusions: PAI provided pain control equivalent to that of a femoral nerve block while avoiding a motor block and its negative functional impacts. The data suggest it should be considered an alternative to a femoral nerve block.

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

Figures

Fig. 1

The study screening and randomization flowchart shows the number of patients who completed the study.

Fig. 2

The postoperative narcotics consumption per period in milligrams of morphine equivalents is shown. The bars represent means and the lines represent 95% CI.

Fig. 3A–B

The pain (A) at rest and (B) during physiotherapy exercises as assessed on a VAS (0–10) on each postoperative day are shown.

Fig. 4A–B

The (A) free and (B) assisted knee flexion on each postoperative day are shown.

Fig. 5

The distances in meters walked on different postoperative days are shown.