Combined Popliteal Catheter with Single Injection Versus Continuous Infusion Saphenous Nerve Block

Abstract

Category: Ankle, Bunion, Hindfoot, Lesser Toes, Midfoot/Forefoot, Sports, Trauma Introduction/Purpose: Surgical and analgesic advancements have increasingly allowed more foot and ankle procedures to be performed on an outpatient basis. Dual nerve blockade of saphenous and popliteal nerves minimizes post-operative pain, and continuous infusion via catheter can provide extended pain relief. In our experience, the combination of popliteal nerve catheters and single-shot saphenous nerve block effectively eliminates post-operative pain after most foot and ankle surgery. However, the early return of pain in the saphenous nerve distribution can cause early discomfort and even readmission for pain control. We hypothesized that patients receiving continuous popliteal nerve infusion with single-injection saphenous nerve block (single) will have greater post-operative pain than those patients receiving continuous popliteal and saphenous nerve infusion (dual). Methods: A cohort of 62 patients undergoing outpatient foot and ankle surgery by a single fellowship trained orthopaedic surgeon were prospectively, sequentially enrolled. The surgeon rated each procedure for degree of saphenous involvement as limited, moderate, or extensive. Demographics, American Society of Anesthesiologists physical status classification system (ASA), anesthesia time and post-anesthesia care unit (PACU) time were documented. Total analgesia requirement and reported numeric pain score (NPS) at rest and with activity were recorded. Student’s t-test and chi-square test were utilized for single and dual block comparisons, and one-way ANOVA tested for differences in saphenous involvement. Results: The dual catheter group took significantly less opioid medication on post-operative day (POD) 1 compared to the single catheter group (Table 1; p=0.02). The dual catheter group reported significantly greater satisfaction with pain at POD 1 and POD 3 (p=0.03) and a significantly lower NPS at POD 1 and POD 2 (p=0.005). This trend is observed in all 3 subgroups of medial involvement. Patients in the single catheter group report about twice as much pain as patients in the dual catheter group when medial involvement was limited (7.4 v 3.8; p=0.033) or moderate (5.9 v 3.4; p=0.025). For patients with extensive medial involvement, pain was reduced when dual blocks were employed (5.4 v 6.7), but this difference was not significant (p=0.288). Conclusion: Patients in the single catheter group reported more pain and less satisfaction with pain control on POD 1, suggesting dual catheter use is superior to managing early post-operative pain in outpatient foot and ankle surgery. Interestingly, degree of medial involvement did not seem to correlate with better pain control within the dual group; in contrast, patients with less medial involvement reported better pain relief with dual than with a single catheter. From a pain management perspective, discharging patients on the day of routine outpatient foot and ankle surgery is appropriate with the judicious use of perioperative continuous infusion nerve catheters.