Measuring Visualized Joint Surface in Hallux Metatarsophalangeal Arthroscopy

Abstract

Category: Arthroscopy, Midfoot/Forefoot Introduction/Purpose: Arthroscopy has been increasingly utilized to evaluate small joints in the foot and ankle. In the hallux metatarsophalangeal (MTP) joint, little data exist evaluating the efficacy of arthroscopy to visualize the articular surface. The goal of this cadaveric study was to determine how much articular surface of the MTP joint could be visualized. Methods: Ten (10) fresh cadaveric foot specimens were evaluated using standard arthroscopy techniques. Arthrosocopy was performed with gravity distraction utilizing a 1.9 mm 30° arthroscope and small joint instruments. The edges of the visualized joint surface were marked with curettes and Kirschner wires; the joints were then surgically exposed and imaged. The percentage of cartilage visualized (visualized / total cartilage x 100%) was measured using ImageJ® software. Measurements include surface area visualized on axial imaging as well as arc visualized on lateral imaging Results: On the distal 2-dimensional projection of the joint surface, an average 57.5% (49.6 – 65.3) of the metatarsal head and 100% (100-100) of the proximal phalanx base were visualized. From a lateral view of the metatarsal head, an average 72° (65-80) was visualized out of an average total articular arc of 199° (192-206), for an average 36.5% (32.2 – 40.8) of the articular arc. Conclusion: The results suggest that hallux MTP arthroscopy visualizes a sizable portion of the joint surfaces. However, incomplete visualization could potentially miss a hallux metatarsophalangeal lesion. Further imaging preoperatively may improve diagnostic confidence.