Saphenous nerve block on medial compartment knee pain in patients with knee osteoarthritis

Abstract

Knee osteoarthritis (KOA) is a common disease in middle-aged and elderly people. Pain is the chief complaint of symptomatic KOA and a leading cause of chronic disability, which is most often found in medial knees. The aim of this study is to evaluate the efficacy of pain relief and functional improvement in KOA patients treated with ultrasound-guided saphenous nerve block (SNB). This is a 3-month retrospective case-controlled comparative study. Two hundred patients with medial knee pain owing to KOA that was unresponsive to 3-month long conservative treatments. Ninety-two patients received SNB with 9 mL of 1% of lidocaine and 1 mL of 10 mg triamcinolone acetonide (SNB group), and 108 continued conservative treatments (control group). The main outcome measure was visual analog scale (VAS) of the average knee pain level for the past one week. Secondary outcomes were the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), the timed up and go test, numbers of analgesic ingestion per day, and opioid consumption per day. During the 3-month follow-up, 86 patients in SNB group and 92 in control group were analyzed. There was no significant difference, with the exception of the duration of symptoms, between the 2 groups in age, sex, body mass index, and Kellgren–Lawrence grade. Repeated measures analysis of variance and post-hoc tests showed improvement of VAS (at month 1), WOMAC (at month 1), and opioid consumption per day (at month 1 and 2) in SNB group. No adverse events were reported. This study looked into the possibility of SNB as an alternative treatment for medial knee pain owing to KOA. Although a palliative treatment, SNB can be an option for patients with refractory KOA who cannot take or are not responsive to analgesics. However, to prove the efficacy of SNB, further studies on prospective randomized controlled trials would be needed.