Decreased Complication Rate Using Partially Threaded Compared With Fully Threaded Compression Screws in 4 Corner Arthrodesis: A Retrospective Study

Abstract

Background: Scapho-lunate advanced collapse (SLAC) and scaphoid nonunion advanced collapse (SNAC) of the wrist are the most common types of wrist arthritis. We compared the union rate and complication profile of patients with SLAC and SNAC wrist undergoing 4 corner arthrodesis with partially threaded or fully threaded headless compression screws.

Methods: A single-center retrospective review was conducted to identify all patients treated for SLAC and SNAC with 4 corner fusion using headless compression screws from 2016 to 2021. A total of 33 patients undergoing surgery on 35 wrists were identified and included in the study. Demographics, comorbidities, complication profile, and radiographs were collected and compared between groups.

Results: One hundred percent (16/16) of partially threaded and 84.2% (16/19) of fully threaded screws demonstrated union by minimum 10-week follow-up. The total complication rate (avascular necrosis of lunate, screw loosening, etc.) was 31.4%; 52.6% of wrists implanted with fully threaded screws experienced complications compared with a 6.3% complication rate with partially threaded screws. The difference was statistically significant between the 2 groups (P = .004).

Conclusions: Four corner arthrodesis using antegrade compression screws is an effective, reproducible method to achieve fusion in the wrist. The use of fully threaded screws was associated with more complications than with partially threaded screws, although union rate was not significantly different. Future studies with larger sample sizes would be useful to fully elucidate differences between these 2 constructs.

Keywords: 4 corner fusion; fusion; radiographic outcomes; scapho-lunate advanced collapse; scaphoid nonunion advanced collapse; wrist arthritis.

Figure 1.

(a) Anteroposterior (AP) and lateral of a patient with scapho-lunate advanced collapse wrist. (b) Intraoperative fluoroscopy after scaphoid excision. (c and d) Immediate postoperative x-rays after 4 corner fusion. (e) AP and lateral at 10 weeks postoperatively showing consolidation of the arthrodesis site.

Figure 2.

(a) A Kirschner wire (K-wire) in the lunate is put to control rotation and burring of the articular surface of capitate, hamate, and lunate. (b) Removal of cartilage. (c) Bone graft is applied in the arthrodesis site. (d) First screw placement: reaming over a K-wire from the lunate to the capitate.

Figure 3.

(a) The first screw is placed from the lunate to the capitate making sure for it to be 4 mm less than the measured length. (b) The wire for the second screw from the triquetrum to the hamate. (c) The second screw from the triquetrum to the hamate. (d) Drilling for the third screw from the lunate to the hamate.

Figure 4.

(a) Preoperative film demonstrating scapho-lunate advanced collapse wrist. (b) Postoperative films demonstrating successful scaphoidectomy with 4 corner fusion achieved with 3 fully threaded screws. (c) Ten-week postoperative films show lucency surrounding screw tips indicative of screw backout (red arrow) in the capitate and sclerosis of lunate consistent with avascular necrosis (blue arrow). (d) Postoperative film of revision surgery with capitate resurfacing.

Figure 5.

(a) Preoperative film demonstrating scapho-lunate advanced collapse wrist. (b) Postoperative films demonstrating successful 4 corner fusion with 3 fully threaded screws. (c) Ten-week postoperative films show lucencies surrounding screw tip and threads indicative of screw backout (red arrow). Radiographic lucency between lunate and capitate is indicative of nonunion (blue arrow).