Skillnad i förekomst av rebound-smärta hos patienter som genomgår operation under popliteal block eller ankelblock (CBFR)

An ultrasound-guided popliteal sciatic nerve block was performed using ropivacaine 0.5% combined with adrenaline (1:400,000) and clonidine (75 μg). The popliteal block generally required 20-30 mL of local anesthetic solution. An additional ultrasound-guided saphenous nerve block was performed when indicated by the surgical territory, with total administered volumes reaching up to 40 mL. The maximum permitted ropivacaine dose was 4 mg/kg, not exceeding 300 mg.

The regional anesthesia technique was combined with standardized general anesthesia induced and maintained using propofol target-controlled infusion (TCI).

Elective forefoot bone surgery under popliteal sciatic nerve

Elective forefoot bone surgery under an ankle block

An ultrasound-guided ankle block was performed using 15-20 mL of ropivacaine 0.5% combined with adrenaline (1:400,000) and clonidine (75 μg). The block targeted the saphenous, superficial peroneal, deep peroneal, and tibial nerves. The maximum permitted ropivacaine dose was 4 mg/kg, not exceeding 300 mg.

The regional anesthesia technique was combined with standardized general anesthesia induced and maintained using propofol target-controlled infusion (TCI).

Elective forefoot bone surgery under popliteal sciatic nerve

Elective forefoot bone surgery under an ankle block

Rebound pain was assessed as severe postoperative pain (NRS ≥7) following initially mild pain (NRS <4) at post-anesthesia care unit discharge, in the context of peripheral nerve block resolution. Incidence was compared between popliteal sciatic nerve block and ankle block groups. A sensitivity analysis used the stricter NRS >7 threshold. The exact onset of severe pain was not systematically timestamped; therefore, the originally registered 24-hour endpoint could not be reliably reconstructed.

Skin temperature (°C) was measured using infrared thermometry on the operated and contralateral feet before and after peripheral nerve block, at emergence from general anesthesia, and on postoperative day 1. Changes over time and their association with rebound pain occurrence were explored.

Tissue oxygen saturation (%) was measured using near-infrared spectroscopy (INVOS) on the operated and contralateral feet before and after peripheral nerve block, at emergence from general anesthesia, and on postoperative day 1. Changes over time and their association with rebound pain occurrence were explored.

The Pain Catastrophizing Scale (PCS) was administered preoperatively to assess pain-related catastrophizing. The total score ranges from 0 to 52, with higher scores indicating greater pain catastrophizing. The PCS score was descriptively reported as a baseline patient characteristic and compared between the popliteal sciatic nerve block and ankle block groups.

The Amsterdam Preoperative Anxiety and Information Scale (APAIS) was administered preoperatively to assess anxiety and information needs related to anesthesia and surgery. The total APAIS score ranges from 6 to 30, with higher scores indicating greater preoperative anxiety and/or information needs. The total score was descriptively reported as a baseline patient characteristic and compared between the popliteal sciatic nerve block and ankle block groups.

The nine-item Central Sensitization Inventory (CSI-9) was administered preoperatively to assess symptoms associated with central sensitization. The total score ranges from 0 to 36, with higher scores indicating a greater burden of symptoms associated with central sensitization. The CSI-9 score was descriptively reported as a baseline patient characteristic and compared between the popliteal sciatic nerve block and ankle block groups.

The Douleur Neuropathique en 4 Questions (DN4) questionnaire was administered preoperatively to assess neuropathic pain characteristics. The total score ranges from 0 to 10, with higher scores indicating more neuropathic pain features. A score of 4 or higher suggests a neuropathic pain component. The DN4 score was descriptively reported as a baseline patient characteristic and compared between the popliteal sciatic nerve block and ankle block groups.

The Douleur Neuropathique en 2 Questions (DN2) questionnaire was administered on postoperative day 4 to assess neuropathic pain symptoms. The questionnaire comprises seven items derived from the DN4, each scored as present (1) or absent (0). The total score ranges from 0 to 7, with higher scores indicating more neuropathic pain symptoms. Scores were compared between the popliteal sciatic nerve block and ankle block groups.

The Douleur Neuropathique en 2 Questions (DN2) questionnaire was administered on postoperative day 30 to assess neuropathic pain symptoms. The questionnaire comprises seven items derived from the DN4, each scored as present (1) or absent (0). The total score ranges from 0 to 7, with higher scores indicating more neuropathic pain symptoms. Scores were compared between the popliteal sciatic nerve block and ankle block groups.

The Douleur Neuropathique en 2 Questions (DN2) questionnaire was administered three months after surgery to assess neuropathic pain symptoms. The questionnaire comprises seven items derived from the DN4, each scored as present (1) or absent (0). The total score ranges from 0 to 7, with higher scores indicating more neuropathic pain symptoms. Scores were compared between the popliteal sciatic nerve block and ankle block groups.

High-sensitivity C-reactive protein (hs-CRP) levels were measured preoperatively (mg/L) as an exploratory marker of baseline systemic inflammation. Values were descriptively compared between the popliteal sciatic nerve block and ankle block groups. Postoperative hs-CRP measurements originally planned in the study protocol were not performed.

The neutrophil-to-lymphocyte ratio (NLR) was calculated from preoperative blood cell counts as an exploratory marker of baseline systemic inflammation. This dimensionless ratio was descriptively compared between the popliteal sciatic nerve block and ankle block groups. Postoperative NLR measurements originally planned in the study protocol were not performed.