Distal Metaphyseal Osteotomy Allows for Greater Ulnar Shortening Compared to Diaphyseal Osteotomy for Ulnar Impaction Syndrome: A Biomechanical Study

Abstract

Purpose To compare the biomechanical characteristics between diaphyseal and metaphyseal ulnar-shortening osteotomy with respect to (1) maximal shortening achieved at each osteotomy site and (2) force required to achieve shortening at each site. Methods Nine fresh frozen cadaveric upper extremities were affixed through the proximal ulna to a wooden surgical board. A metaphyseal 20-mm bone wedge was resected from the distal ulna and sequential shortening was performed. A load cell was attached to a distal post that was clamped to the surgical board and used to measure the force required for each sequential 5-mm of shortening until maximal shortening was achieved. The resected bone was reinserted, and plate fixation was used to restore normal anatomy. A 20-mm diaphyseal osteotomy was performed, and force measurements were recorded in the same manner with (1) interosseous membrane intact, (2) central band released, and (3) extensive interosseous membrane and muscular attachments released. Results Metaphyseal osteotomy allowed greater maximal shortening than diaphyseal osteotomy with the interosseous membrane intact and with central band release but similar shortening when extensive interosseous membrane and muscle release was performed. Force at maximal shortening was similar between metaphyseal and diaphyseal osteotomy. Sequential soft tissue release at the diaphysis allowed for increased shortening with slightly decreased shortening force with sequential release. Conclusion Metaphyseal ulnar osteotomy allows greater maximal shortening but requires similar force compared with diaphyseal osteotomy. Sequential release of the interosseous membrane permits increased shortening at the diaphysis but requires extensive soft tissue release. Clinical Relevance Both sites of osteotomy can achieve sufficient shortening to decompress the ulnocarpal joint for most cases of ulnar impaction syndrome. The greater shortening from metaphyseal ulnar osteotomy may be reserved for severe cases of shortening, especially after distal radius malunion or in the setting of distal radius growth arrest in the pediatric population. Level of Evidence This is a Level V, basic science study.

Comparison of diaphyseal and metaphyseal ulnar shortening osteotomies for the treatment of ulnar impaction syndrome

“…Moreover, we found that metaphyseal USO generally had a shorter operative time than diaphyseal USO. The shorter operation time in the metaphyseal USO group indicated that this type of osteotomy is easier to perform, which could be related to several points, as Owing to the abundant blood supply and less resistant to osteotomy, a metaphyseal USO is considered to provide better bone healing potential than a diaphyseal USO [28], which is consistent with our findings. Despite these theoretical advantages, bony union was achieved in all patients in this study, regardless of the surgical technique, in line with previous findings [8,26,27].…”

Guidelines for the Diagnosis and Treatment of Ulnar Impaction Syndrome (2024)

“…However, evidence for ulnar-positive variance at or ≥5 mm is currently lacking, even though a cadaveric study suggests that DMUSO may have a similar or longer osteotomy distance compared with USO. 61 Researchers observed that DMUSO was more effective than USO in relieving pain and Quick-DASH scores were higher. 62 Additionally, due to the distal location of the osteotomy in DMUSO, it reduced the separation and traction effects of the interosseous membrane on the osteotomy ends.…”

Clinical Study of Wrist Arthroscopy Combined with Oblique Ulnar Shortening Osteotomy in the Treatment of Ulnar Impaction Syndrome

“…Transverse osteotomy is relatively simple, but the contact area of both ends of the fracture is small, and is prone to rotation displacement, so the fracture healing time is long. The contact area of both ends of V‐shaped and trapezoidal osteotomy fractures is large, and the anti‐rotation force is enhanced, but the operation is more complicated, the operation time is long, and the two ends of the fracture are prone to malalignment 9 . However, oblique osteotomy is easy to perform, with a large contact area and strong anti‐rotation force, so it is widely used in the clinic 10 .…”