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Proximal Interphalangeal Arthroplasty According to Finger; Do Border Digits Perform Worse Than Middle Digits?
Eric R. Wagner, MD; William Robinson, MD; John Weston, MD; Steven L. Moran, MD; Marco Rizzo, MD
Mayo Clinic, Rochester, MN

Purpose: Although it is traditionally thought proximal interphalangeal (PIP) arthroplasties perform worse on border (2nd or 5th) digits, there is a paucity of studies examining this thought. The purpose of this investigation was to assess the correlation between border digits and outcomes after PIP arthroplasty.

Methods: Over a 14 year period, 110 consecutive primary PIP arthroplasties were performed on border digits, either the 2nd (n=75) or 5th (n=35). This was compared to 195 arthroplasties performed in either the 3rd (n=122) or 4th (n=73) non-border digits. Demographics of border (vs. non-border) arthroplasties include 68% female (vs. 77%), average age of 60 years (vs. 60), with diagnoses of inflammatory arthritis (25% vs. 30%), osteoarthritis (57% vs. 53%), and post-traumatic arthritis (18% vs. 17%). Implants utilized included pyrocarbon (65% vs. 63%), silicone (5% vs. 7%) and SRA (30% vs. 30%).

Results: There were 20 PIP arthroplasties in the border digits (13 in 2nd, 7 in 5th) that required revision surgery at a mean 0.7 years postoperatively. Etiologies include pain and stiffness (n=10), dislocation (n=6) implant fracture (n=1), and infection (n=3). Risk of revision surgery was not associated with border digit (HR 1.04, p=0.88). The 2, 5, and 10-year implant survival rates for the border digits were 83%, 81%, and 81%, respectively, which was not different from the non-border digits (Figure 1). Amongst border digits, younger patients and those requiring bone grafting had increased risks of implant failure (Table 1). Silicone implants had improved implant survival compared to pyrocarbon or SRA (Figure 1). Diagnosis did not influence risk of revision surgery. Complications in the border digits included dislocation (n=6), infection (n=6), intraoperative fracture (n=6), and postoperative fracture (n=1). The risk of dislocation was not different in border versus non-border digits. In unrevised border digits at a mean 4.8 years follow-up (1-11), preoperative to postoperative pain levels significantly improved border digit arthroplasties (p<0.001). PIP total arc of motion did not improve from 38o preoperatively to 36o postoperatively (p=0.71), with no improvements in pinch or grip strength. Non-border digits had better PIP arc of motion (46o) compared to border digits (p=0.03).

Conclusions: PIP arthroplasty performed in border digits had similar outcomes to those performed in non-border digits. Implant choice and diagnosis do not effect these outcomes. However, these border digit arthroplasties have worse PIP motion. However, PIP arthroplasty performed in border digits results in predictable pain relief, preservation of range of motion, with low complications.

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