Objective : To identify the efficacy of ultrasound-guided adductor canal block (ACB) as a therapeutic option for refractory anteromedial knee pain owing to knee osteoarthritis (KOA)
Methods : Seventeen patients with anteromedial knee pain owing to KOA were randomly allocated to either ACB group (n=8) or placebo group (n=9). Inclusion criteria were (1) patient with anteromedial knee pain for at least 3 months and diagnosed with osteoarthritis by physical examination and X-ray, (2) at least or above 45 years, and (3) grade of Kellgren-Lawrence grading scale 2 to 4 of osteoarthritis. Exclusion criteria were (1) presence of other obvious knee pathology, such as a fracture, infection or rheumatic diseases or (2) prior surgery to the knee. In ACB group, ultrasound-guided ACB was performed in the medial side of thigh by 1% lidocaine 10ml. In placebo group, 1% lidocaine 1ml injected to the sartorius muscle. The primary outcome was visual analog scales (VAS) for knee pain intensity compared for pre-, and 4 weeks post-injection. The secondary outcome were 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 compared for pre-, and 4 weeks post-injection.
Results : There are no significant differences in baseline characteristics of patients between two groups. At 4 weeks post-injection, ACB group shows significant difference on VAS compared to control group (P<0.05). However, WOMAC, the timed up and go test, numbers of analgesic ingestion per day and opioid consumption per day do not show significant difference. And there were no adverse events reported such as bleeding, infection, cellulitis, or weakness.
Conclusions : To our knowledge, this is the first prospective study to assess the efficacy of ACB for patients with KOA. ACB may be an effective and safe treatment option for patients who are either unresponsive or unable to take analgesics.
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