Prevalence of chronic pain syndrome in patients who have undergone hallux valgus percutaneous surgery: a comparison of sciatic-femoral and ankle regional ultrasound-guided nerve blocks

BACKGROUND: Chronic pain syndrome (CPS) is a common complication after operative procedures, and only a few studies have focused on the evaluation of CPS in foot-forefoot surgery and specifically on HV percutaneous correction. The objective of this study was to compare postoperative pain levels and incidence of CPS in two groups of patients having undergone femoral-sciatic nerve block or ankle block regional anaesthesia before hallux valgus (HV) percutaneous surgery and the association between postoperative pain levels and risk factors between these patient groups. METHODS: A consecutive patient series was enrolled and evaluated prospectively at 7 days, 1, 3 and 6 months after surgery. The participants were divided into two groups according to the regional anaesthesia received, femoral-sciatic nerve block or ankle block, and their outcomes were compared. The parameters assessed were postoperative pain at rest and during movement by the numerical rating scale (NRS), patient satisfaction using the Visual Analogue Scale (VAS), quality of life and return to daily activities. Statistical analysis was performed. RESULTS: One hundred fifty-five patients were assessed, 127 females and 28 males. Pain at rest (p < 0.0001) and during movement (p < 0.0001) significantly decreased during the follow-ups; at 6 months, 13 patients suffered from CPS. Over time, satisfaction remained stable (p > 0.05), quality of life significantly increased and patients returned to daily activities and work (p < 0.0001). No significant impact of type of anaesthesia could be detected. ASA 3 (p = 0.043) was associated to higher pain during movement; BMI (p = 0.005) and lumbago (p = 0.004) to lower satisfaction. No operative-anaesthetic complications were recorded. Postoperative pain at rest and during movement improved over time independently of the regional block used, with low incidence of CPS at last follow-up. Among risk factors, only a higher ASA was associated to higher pain during movement, while higher BMI and lumbago to lower satisfaction. CONCLUSIONS: Both ultrasound-guided sciatic-femoral and ankle blocks were safe and effective in reducing postoperative pain with low incidence of CPS at last follow-up. TRIAL REGISTRATION: Clinical Trial NCT02886221. Registered 1 September 2016.