# Midterm Outcomes of Four-Corner Fusion Surgery Using Nitinol Staples

## TL;DR

This study shows that using Nitinol staples for wrist surgery leads to good recovery in motion, strength, and patient satisfaction over a two-year period.

## Contribution

The study presents midterm outcomes of four-corner fusion using only Nitinol staples, a less commonly reported fixation method.

## Key findings

- Patients maintained 76% wrist flexion-extension and 83% radial-ulnar deviation compared to the contralateral side.
- All patients achieved radiographic union with intact hardware, and reported low pain levels and high satisfaction.
- Patient-reported outcomes showed a mean Quick DASH score of 17 and a Michigan Hand Outcomes score of 85%.

## Abstract

Wrist arthritis because of scaphoid nonunion advanced collapseand scapholunate advanced collapse can be treated through scaphoid excision and four-corner arthrodesis. There are many fixation techniques; however, there are few studies reporting outcomes in which only Nitinol staples were used. This study aimed to evaluate whether patients undergoing a four-corner arthrodesis using this fixation technique as well as intraoperative modifications to minimize complications will have successful outcomes.

Retrospective study of patients who underwent scaphoid excision and four-corner arthrodesis using DynaNite Nitinol Staple (Arthrex Inc) to treat scaphoid nonunion advanced collapse or scapholunate advanced collapse wrist arthritis at a single academic institution by a single surgeon. The technique and our modifications are described below. Outcome measures included radiographic union, range of motion, strength, and patient-reported outcomes such as Quick Disabilities of the Arm, Shoulder, and Hand, Michigan Hand Outcomes questionnaire, Likert patient satisfaction scale, and the visual analog scale.

Eight patients were included with mean follow-up of 27 months (9–42 months). When compared to the contralateral side, patients maintained 76% wrist flexion-extension, 83% radial-ulnar deviation, and 99% pronation-supination. Key pinch, three-point pinch, and grip strength testing were 95%, 89%, and 86%, respectively. The mean Quick Disabilities of the Arm, Shoulder, and Hand score was 17, and the mean Michigan Hand Outcomes score was 85% compared to the contralateral side. The visual analog pain scale had a mean of 2.5 (range 0–6). Radiographic imaging showed that all patients had undergone union of their four-corner arthrodesis with intact hardware.

The results of this study show that midterm outcomes of four-corner fusions performed with Nitinol staples have promising results in overall functional and patient-reported outcomes. In addition, they offer reliable fixation for achieving union of the four-corner arthrodesis.

Therapeutic IV.