Disappearing in Size and Relevance over Time: The Scaphometacarpal Space
Kevin T Rezzadeh, BA1, David Daar, MD2, Megan Donnelly, BS3, Louis W Catalano, MD4, Steven Z Glickel, MD1 and Jacques Hacquebord, MD5, (1)New York University School of Medicine, New York, NY, (2)New York University Langone Health, New York, NY, (3)NYU School of Medicine, New York, NY, (4)New York University Hospital for Joint Diseasses, New York, NY, (5)NYU Langone Medical Center, New York, NY
A common notion is that more complex techniques involving some type of metacarpal suspension for treating trapeziometacarpal arthritis better preserve the scaphometacarpal (SMC) space compared to a simple trapeziectomy and that this leads to superior functional outcomes. No study to date has systematically reviewed the literature regarding the relationship between scaphometacarpal space and functional outcomes such as grip and pinch strength. Herein, we aim to reconcile the disparity between clinical practice and evidence-based study on the functional importance of the SMC space.
A systematic review of the literature was conducted according to PRISMA guidelines. Inclusion criteria were studies reporting outcomes after surgery for CMC arthritis. Specifically, studies on patients undergoing the following surgeries were included: trapeziectomy [T], partial trapeziectomy [PT], trapeziectomy with ligament reconstruction [LR], trapeziectomy with hematoma distraction arthroplasty [HDA], trapeziectomy with interposition arthroplasty [IA], trapeziectomy with interposition arthroplasty [IA], trapeziectomy with ligament reconstruction and tendon interposition [LRTI], and trapeziectomy with suture button suspensionplasty [SBS]. The primary outcomes of these studies included any measure of postoperative scaphometacarpal space (trapezial height/trapezial index) as well as key pinch strength, grip strength, or lateral pinch strength. Studies that did not assess the association between SMC space and outcomes were excluded.
Fourteen studies and 433 patients were included for analysis. Three studies (21.4%) found a statistically significant correlation between postoperative SMC space and postoperative pinch or grip strength. The correlation was weakly positive in one study (key pinch force vs. scaphometacarpal space, p=<0.05, r=0.13), positive but unlisted in another (lateral pinch vs. trapezial ratio, p=0.03), and negative in the third study (key pinch vs. trapezial space ratio, p=0.02, r=-0.47). The other 11 studies (78.6%) found no association between SMC space and postoperative strength.
Discussion and Conclusion:
Preservation of the SMC space postoperatively is generally not associated with postoperative functional outcomes of grip and pinch. Further research is necessary to better characterize the importance of maintaining the SMC space in patients undergoing trapeziectomy in order to substantiate claims by proponents of more invasive variants of simple trapeziectomy.
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