Four-Corner Fusion in SLAC & SNAC Wrist: Does Fixation Method Really Make A Difference?
Logan A McGinn, MD, BScN; University of Western Ontario, London, ON, Canada; Roth|McFarlane Hand and Upper Limb Centre, London, ON, Canada; Ruby Grewal, MD, MSc, FRCSC; Roth|MacFarlane Hand and Upper Limb Centre, University of Western Ontario, London, ON, Canada
Four-corner fusion (4CF) has traditionally been reported to have a higher complication rate with similar functional outcomes as the PRC. To date, there have been limited comparisons that specifically focus on whether the fusion method utilized in 4CF affects functional outcomes and complication rates. In this study, we explored the differences in outcomes of two different fixation methods in 4CF and how these compare to traditionally reported 4CF outcomes in the literature.
Materials & Methods
A retrospective chart review was conducted to compare headless compression screw (HCSF) versus staple fixation (SF) in four-corner fusion for SLAC or SNAC wrist in a single surgeon's practice over a ten-year period. Primary functional outcomes included pre- versus post-operative flexion-extension arc and grip strength, complication rate and time to fusion. Two-tailed T-tests were used to compare the outcomes of HCSF and SF methods. The Chi-squared test was used to evaluate the complication rates associated with each method.
Sixty-four patients were identified; 38 patients were treated with HCSF and 26 with SF. The majority of patients were male (84%) with an average age of 60.2 years and 52.9 in the HCSF & SF groups, respectively. Patients were followed on average for a 10-month period. HCSF patients had improved flexion arc post-operatively (108% of pre-operative arc), whereas SF patients lost an average of 30.4% of their pre-operative range (p-value:0.00003). Grip-strength was improved in both groups. A statistically significant higher complication rate was associated with SF (50%) versus HCSF (13.2%). Hardware irritation/pain (6), delayed union (4) and nonunion (1) were the most common complications of SF, where as neuropraxia (2) and hardware failure (2) were the most common complications associated with HCSF. The higher complication rate and equivocal functional outcomes traditionally reported for 4CF may be associated with specific fixation methods such as the SF.
Various fixation methods are available for 4CF, however functional outcomes and complication rates are inconsistent among these methods. Patients undergoing 4CF with headless compression screw fixation have better arc of motion and a lower complication rate than those treated with staple fixation. Although 4CF is reported to have a higher complication rate than PRC in the literature, various fixation options are available and may be a key factor contributing to this discrepancy.
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