Unipolar ulnar head replacement for treatment of post-Darrach procedure instability.

The aim of this study was to assess distal radioulnar joint stability after unipolar ulnar head replacement for post-Darrach instability. All the patients who underwent ulnar head replacement between1999 and 2015 for post-Darrach procedure instability at our clinic were reviewed. Seven Hebert-type and two uHead (SBI/Stryker) prostheses were implanted. None of the implants were cemented. We assessed stability, pain, range of motion and strength pre- and postoperatively. The changes in the radiographic appearance between immediate postoperative and the last follow-up were determined. All patients (8 patients and 9 joint replacements) had a stable distal ulnar stump at the mean follow-up of 69 months. No complications occurred and no revisions were needed. Pain on a visual analog scale (VAS) was 0 at rest and 6 during maximum effort at the last follow-up; it was 1.5 at rest and 8.5 during effort preoperatively. Wrist flexion and extension, supination and grip strength were unchanged. Pronation increased from 45° to 70°. An area of bone resorption proximal to the ulnar head implant was found in 5 cases but no secondary displacement of the implant or increased pain was reported. Ulnar head replacement stabilizes the ulnar stump. The implant acts as a spacer to place the soft tissues under tension. Distal ulnar stump instability after the Darrach procedure can be solved by a unipolar ulnar head replacement procedure.

Ultrasound-guided surgical treatment for ulnar nerve entrapment: a cadaver study.

Several open and endoscopic techniques for the surgical treatment of ulnar nerve entrapment at the elbow (cubital tunnel syndrome) have been described that provide decompression with or without anterior transposition. Based on our experience with US-guided decompression for carpal tunnel syndrome in our department, we developed a similar surgical technique for the decompression of the ulnar nerve at the elbow. Using sixteen cadaver upper limbs, we performed decompression of all the structures possibly responsible for ulnar nerve compression at the elbow. The structures involved were Struthers' arcade, the cubital tunnel retinaculum, Osborne's fascia and Amadio-Beckenbaugh's arcade. The procedure was followed by anatomical dissection to confirm complete sectioning of the compressive structures, absence of iatrogenic vascular or nervous injuries and absence of nerve dislocation or instability. There were no remaining compressive structures after the release procedure. There was no iatrogenic damage to the nerves and no nerve dislocation was observed during elbow flexion or extension. In 3.4% cases, a thin superficial layer of one or more of the identified structures remained but these did not appear to compress the nerve based on US imaging. Using ultrasonographic visualization of the nerve and compressive structures is easy. Each procedure can be tailored according to the nerve compression sites. Our cadaveric study shows the feasibility of an US-guided percutaneous surgical release for ulnar nerve entrapment.