BACKGROUND: Two of the more common methods of pain management after TKA are peripheral nerve blocks and intraarticular/periarticular injections. However, we are not aware of any study directly comparing the commonly used combination of a continuous femoral block given with a single-shot sciatic block with that of a periarticular injection after TKA.
QUESTIONS/PURPOSES: This randomized clinical trial compared a combined femoral and sciatic nerve block with periarticular injection as part of a multimodal pain protocol after total knee arthroplasty with respect to (1) pain; (2) narcotic use; (3) quadriceps function and length of stay; and (4) peripheral nerve complications.
METHODS: One hundred sixty patients completed randomization into two treatment arms: (1) peripheral nerve blocks (PNB; n=79) with an indwelling femoral nerve catheter and a single shot sciatic block; or (2) periarticular injection (PAI; n=81) using ropivacaine, epinephrine, ketorolac, and morphine. All patients received standardized general anesthesia and oral medications. The primary outcome was postoperative pain, on a 0 to 10 scale, measured on the afternoon of postoperative day 1 (POD 1). Secondary outcomes were narcotic use, quadriceps function, length of stay, and peripheral nerve complications.
RESULTS: Mean pain scores on the afternoon of POD 1 were not different between groups (PNB group: 2.9 [SD 2.4]; PAI group: 3.0 [SD 2.2]; 95% confidence interval, -0.8 to 0.6; p=0.76). Mean pain scores taken at three times points on POD 1 were also similar between groups. Hospital length of stay was shorter for the PAI group (2.44 days [SD 0.65] versus 2.84 days [SD 1.34] for the PNB group; p=0.02). Narcotic consumption was higher the day of surgery for the PAI group (PAI group: 11.7 mg morphine equivalents [SD 13.1]; PNB group: 4.6 mg [SD 9.1]; p<0.001), but thereafter, there was no difference. More patients in the PNB group had sequelae of peripheral nerve injury (mainly dysesthesia) at 6-week followup (nine [12%] versus one [1%]; p=0.009).
CONCLUSIONS: Patients receiving periarticular injections had similar pain scores, shorter lengths of stay, less likelihood of peripheral nerve dysesthesia, but greater narcotic use on the day of surgery compared with patients receiving peripheral nerve blocks. Periarticular injections provide adequate pain relief, are simple to use, and avoid the potential complications associated with nerve blocks.
LEVEL OF EVIDENCE: Level I, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.
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