Partial Trapeziectomy with Capsular Interposition (PTCI) Arthroplasty for Surgical Treatment of Thumb Carpometacarpal Osteoarthritis (Abstract # 8193) Deana Mercer, MD; Moheb Moneim, MD; Nathan Morrell, MD; Christina Salas, PhD

Disclosure The authors have nothing to disclose

Introduction Osteoarthritis (OA) of the thumb carpometacarpal (CMC) joint disproportionately affects men and women >60 y/o with a female predominance Many surgical treatment options exist to treat late stage OA These techniques may require significant disruption of soft tissue stabilizing structures and bony supports We present a technique of partial trapeziectomy with capsular interposition (PTCI) arthroplasty which minimizes disruption of soft tissue structures while adequately treating the affected joint We report on short-term and medium-term results following treatment with PTCI

Methods: PTCI Technique Elevation of the periosteum, including the abductor pollicis longus and extensor pollicis brevis tendons, off the base of the first metacarpal Resection of 2 mm from the base of the first metacarpal and 2 mm from the distal trapezium, leaving the capsule attached to the trapezium (Figure 1) Capsular interposition of dorsal capsule with deep capsular tissue in the joint space (Figure 2) Reefing the elevated periosteal flaps, including the abductor tendon, on the dorsal surface of the first metacarpal to stabilize the joint Figure 1 Figure 2 Moneim MS, Morrell NT, Mercer DM. Tech Hand Up Extrem Surg. 2014 Sep;18(3):116-20.

Methods: Clinical Studies Between January 2003 and December 2009, 62 patients had surgery for treatment of thumb CMC OA using the PTCI technique 23 patients were excluded due to inadequate pre-operative pinch and/or grip strength documentation A short-term retrospective review of 39 cases was completed at a mean of 6 months post-op; Pre-op vs. short-term post-op grip and pinch strength and complications are reported Eighteen patients (46% of qualifying patients) returned for medium term follow-up (mean 51 months); Pre-op and short-term post-op vs. medium-term post-op pinch and grip strength, contralateral limb strength, first web-space distance, and DASH scores are reported

Results: Short-term Retrospective No significant difference was found between pre-op and short-term follow-up for grip (22.6+/-11.1 kg vs. 23.0+/-9.5 kg; p=0.75) or pinch strength (5.5+/-3.3 kg vs. 5.0+/-2.0 kg; p=0.20) Complication rate 5%-pin site infections

Results: Medium-term Follow-up The mean grip strength value for the treated hand was 71.9% of that for the contralateral hand pre-operatively and increased to 95.2% (23.1% increase) by the time of the long-term evaluation. The mean pinch strength in the treated hand was 66.1% of that in the contralateral hand pre-operatively and increased to 89.3% (23.2% increase) by the time of the long-term evaluation. Excellent DASH scores were reported (median 4.17, range 0.83-15.52) No additional complications were reported

Discussion PTCI may be a viable option for treatment of thumb CMC arthritis with less disruption of surrounding soft tissues, no need for tissue harvest, and acceptable patient outcome in the short and medium term.

Summary Points The PTCI procedure results in improved grip and pinch strength at medium-term follow-up Excellent DASH scores were achieved This procedure is simple to perform, reproducible, easily taught to hand surgeons and provides a stable thumb without the need for tendon suspension or prosthetic replacement