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Intraoperative Assessment of Scapho-Trapezoid Arthritis during Thumb Carpometacarpal Arthroplasty: A Cadaveric Study
Michael Rivlin, MD, Rothman Institute at Thomas Jefferson University, Philadelphia, PA, Bryan Hozack, MD, Rothman Institute, Philadelphia, PA, Brianna Fram, MD, Thomas Jefferson University, Philadelphia, PA, Christopher Jones, MD, Orthopaedics, Rothman Institute at Thomas Jefferson University Hospital, Philadelphia, PA and Asif M Ilyas, M.D., The Rothman Institute, Philadelphia, PA



Hypothesis:

Due to limited sensitivity of radiographs for scaphotrapeziotrapezoid (STT) osteoarthritis (OA) and the high rate of concurrence between thumb carpometacarpal (CMC) and STT arthritis, intraoperative visualization of the STT joint is recommended during surgery for CMC arthroplasty. We hypothesized the visualized area of the trapezoid articular surface of the scaphotrapezoid joint is limited during this approach.

Methods:

Investigation was carried out using eleven cadaver upper extremities. Pre-dissection fluoroscopic images were taken of the wrist using standard views. Wagner surgical approach to the thumb CMC was then performed and the trapezium was removed, revealing the scaphotrapezoid joint. The visualized portion of the trapezoid articulation was marked with an electrocautery. The trapezoid was then removed in its entirety, photographed, and the marked surface area and total surface area were measured using ImageJ image analysis software to calculate the percentage of the joint surface that had been marked. Two authors independently took two measurements of each trapezoid, and these values were averaged. The radiographs were analyzed for the presence of STT arthritis using the system described by White et al. One-wau ANOVA was used to determine if there was a significant association between radiographic degree of arthritis and percentage of the joint visualized during surgery.

Results:

The mean surface area of the trapezoid visualized during standard approach for CMC arthroplasty was 60.3% (standard deviation 24.6%). There was a wide range, 16.7-96.5%, but we did not find a correlation between degree of radiographic arthritis of the scaphotrapezoid joint and percentage of the joint that was visualized. The degree of radiographic STT arthritis could not

be used to predict ease of visualization of the scaphotrapezoid joint intraoperatively during CMC arthroplasty.

Summary:

  • 60% of the trapezoid proximal articular surface was visualized during excision of trapezium of the thumb. This may not be sufficient to dictate intraoperative management of the trapezoid.
  • A combination of clinical examination, pre- and intraoperative radiographs, and intraoperative visualization should be utilized to assess for STT OA and determine the need for surgical treatment.

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