gms | German Medical Science

Objectives/Interrogation: Several upper limb deformities can cause functional impairment and pain due to forearm instability and/or proximal migration of the radius. The creation of a single-bone-forearm has been shown to be a successful intervention to stabilize the forearm though at the cost of a loss of pro- and supination. Despite the reported good outcomes in small case series, it remains unknown how patients are capable to compensate for the lack of forearm rotation. This is particularly important as e.g. shoulder or wrist overuse may eventually lead to joint degeneration. The purpose of this study was therefore to analyse this patient cohort while performing well-defined functional tasks in order to obtain information about joint motion and potential compensation mechanisms.

Methods: We performed a prospective re-evaluation of 4 patients (3 children, 1 adult) who underwent single-bone-forearm surgery due to radial longitudinal deficiency (n=1), ulnar longitudinal deficiency (n=2), and a posttraumatic forearm deformity (n=1), respectively. Patients were clinically assessed using the Southampton hand assessment procedure (SHAP test) and Disabilities of the Shoulder, Arm and Hand (DASH) score, and a 3D-motion capture analysis was performed to specifically evaluate the performance of important tasks of daily life activities.

Results and Conclusions: Overall, a wide spectrum of functional impairment and deviation from the norm was observed. Both concerning the time to do certain tasks (e.g. turn a book page, pour a glass of water, rotate a key) as well as the quality of performance (linear index of function; LIF, and APS items), some patients showed normal behavior and function while others presented markedly altered mechanisms to achieve their tasks. Nevertheless, all cases were able to complete the tasks as requested. Compensatory movements were found in the trunk, shoulder, elbow and wrist, respectively (sagittal, frontal, transverse plane). No unique, distinct mechanism of compensation was however identifiable. Postoperative DASH scores ranged from excellent to poor (7 to 61 points).

Patients who received single-bone-forearm surgery are generally capable to perform important tasks of daily life. However, the time to achieve these tasks may be longer, and compensatory movements in several other joints are necessary to achieve these outcomes. Further long-term studies with more patients are warranted to assess any degenerative effects of these potential overuse movements.