Ultrasound-guided needle knife for releasing Osborne's ligament: an anatomical study

There is a lack of effective clinical options for treating mild-to-moderate cubital tunnel syndrome (CuTS) that does not fulfill the surgical indications, as more conservative treatments are ineffective. In this study, we investigated the anatomical characteristics of a CuTS caused by ligament compression to propose a new procedure for incising Osborne's ligament with a needle knife. We evaluated the safety and efficacy of Osborne's ligament release under the guidance of ultrasound.

The study involved an anatomical examination of the cubital tunnel in 25 adult specimens to summarize the anatomical characteristics of the cubital tunnel. We examined the feasibility of using a needle knife to incise Osborne's ligament. A comparison was made between the non-ultrasound-guided and ultrasound-guided procedures to assess the benefit of ultrasound guidance.

The ultrasound-guided group (group U) consisted of 25 specimens, 3 of which displayed nerve or blood vessel injuries; meanwhile, the non-ultrasound-guided group (group N) consisted of 24 specimens, 6 of which displayed nerve injury. The effective rate of ligament release in group U was 80.00% while that in group N was 79.23%. The mean thickness of Osborne's ligament was 0.050±0.026 mm, the mean width was 17.92±3.07 mm, and the mean actual length was 36.02±5.04 mm. The actual length of Osborne's ligament was greater in males than in females (P=0.02); however, no statistically significant difference was found in terms of thickness or width between males and females or between the right and left hands. The contents of the cubital tunnel primarily consisted of the ulnar nerve and superior ulnar collateral artery. Nerves and blood vessels were predominantly present in the middle of Osborne's ligament.

Ultrasound-guided needle knife for incising Osborne's ligament is safe and effective. This can be a novel treatment option for CuTS that does not fulfill surgical indications.