A Feasibility Study on Using Hanging Arm Test to Assess Elbow Stability During Surgical Treatment for Varus Posteromedial Rotatory Instability

Abstract

Objectives: The aim of this study to investigate the safety and effectiveness of performing the hanging arm test during surgical treatment for elbow varus posteromedial rotatory instability (VPMRI) to assess elbow stability and determine whether to repair the lateral ulnar collateral ligament (LUCL).

Methods: In a retrospective study from August 2014 to March 2019, 27 patients with VPMRI who had a negative result in the hanging arm test after fixation of coronoid fracture were selected. Intraoperative bleeding, operative time, elbow range of motion (ROM), and complications were recorded. Elbow function was evaluated with the Mayo elbow performance score (MEPS) and the disabilities of the arm, shoulder, and hand (DASH) score.

Results: The operation time was 85.9 ± 11.06 min (range 65-110). The intraoperative blood loss was 70.7 ± 9.31 ml (range 60-100). At the last follow-up, the elbow joint averaged 73.8° ± 2.931° in pronation, 78.9° ± 2.941° in supination, 7.2° ± 3.207° in extension, and 123.3° ± 6.651° in flexion. The MEPS score was 90.7 ± 4.36 (range 74-95), and the DASH score was 9.8 ± 2.58 (range 6.67-13.3). One patient presented with symptoms of ulnar nerve entrapment 2 months after operation and was treated with ulnar nerve release. The symptom of numbness went away completely 1 week after operation. No complications such as wound infection, arthritis, or chronic instability of the elbow were found in the other patients.

Conclusion: Our findings suggest that not all VPMRI patients need the LUCL to be repaired, and the hanging arm test is a safe and reliable method to assess whether to repair the LUCL in the treatment of elbow VPMRI.

Level of evidence: Level IV; Retrospective studies.

Keywords: Feasibility study; Hanging arm test; Varus posteromedial rotatory instability.

Fig. 1

Schematic of the hanging arm test

Fig. 2

The hanging arm test. Patients under anesthesia, the upper arm is elevated, the forearm is supinated, and the elbow is kept straight and in suspension. If the elbow joint can maintain concentric reduction in the lateral fluoroscopic view, and the humeral radial joint and humeral ulnar joint can maintain normal alignment in the orthogonal fluoroscopic view, the hanging arm test result is negative, which indicates a stable elbow joint; otherwise, the hanging arm test result is positive, which indicates an unstable elbow joint

Fig. 3

A 43-year-old female, fell, resulting in a right ulna coronoid process anteromedial fracture (O’Driscoll classification Type-2, Subtype-2). The patient was treated three days after injury with open reduction and plate fixation of the right ulna coronoid process. 1A, 1B Anterior and lateral radiographs revealed right ulna coronoid process fractures. 2A Preoperative CT three-dimensional reconstruction showed the fracture of the right ulnar coronoid process. 2B–2D Preoperative CT showed the fracture of the coronoid process involving the medial aspect of the coronoid process and the apex of the coronoid process. 3A, 3B The right elbow joint was reexamined two days after operation. The X-ray films showed that the fracture reduction was good. 4A, 4B One year postoperatively, the fracture healed well on the right elbow joint X-ray. 4C–4F The flexion, extension, and rotation of the right elbow returned to normal at the end of one year. The flexion and extension of the elbow was 0°–135°, pronation was 80°, and supination was 85°