AAHS Home  |  2021 Virtual Portal  |  Past & Future Meetings
American Association for Hand Surgery

Back to 2022 ePosters

Is it Safe to Immediately Mobilize Ulnar Shaft Fractures after Fixation?
Lauren E Dittman, MD1, Katharine M Hinchcliff, MD2, Alexander W Hooke, MA1 and Sanjeev Kakar, MD, FAOA3, (1)Mayo Clinic, Rochester, MN, (2)Department of Surgery, Division of Plastic Surgery, University of California San Diego, San Diego, CA, (3)Orthopaedics, Mayo Clinic, Rochester, MN

Pronosupination about the forearm is a complex interplay between the carpus, radius, ulna, and interosseous membrane. Previous cadaveric studies have shown that the interosseous membrane functions more as a longitudinal stabilizer rather than for rotational stability during pronosupination1. However, many surgeons advocate for above-elbow immobilization after plating of the ulna in order to prevent forearm rotation. The aim of this study was to identify the amount of motion at the site of an ulnar fracture during pronosupination.

Materials & Methods
A sample of convenience of 7 paired-matched cadavers were used for this study. The arm was positioned as seen in Figure 1 and a force was applied to move the forearm through 10 cycles of pronation and supination. A Hall effect sensor was used to monitor micro-motion at the fracture. Four conditions were tested: intact ulnar shaft with plate, fracture without stabilization, fracture with cortical apposition stabilized with plate, and a comminuted fracture stabilized with plate. The amount of displacement was recorded in millimeters, and a repeated measures ANOVA with Tukey HSD post hoc analysis with alpha=0.05 was used to compare the differences between the conditions tested.

There was increased micromotion at the fracture site in the comminuted fracture compared to both the intact and the plated fractures, however this was not statistically significant (Figure 2). The post hoc comparisons between the different test conditions are listed in Table 1.

Prior to this investigation, little was known regarding energy transmission from the radius across the interosseous membrane to the ulna during pronosupination. This study showed that plated ulnar fractures, even with comminution, have a comparable amount of motion between the ends of the bone as an intact ulnar shaft during pronosupination. This information may help guide clinicians regarding their post-operative protocols moving forward.


  1. Bin Abd Razak HR, Andy Yew KS, Bin Mohd Moideen IS, Kenny Tay XK, Howe TS, Joyce Koh SB. An anatomical and biomechanical assessment of the interosseous membrane of the cadaveric forearm. J Hand Surg Eur Vol. 2020 May;45(4):369-374.

Back to 2022 ePosters