Trapeziometacarpal osteoarthritis: Arthroscopic hemitrapeziectomy using the Thenar Portal

Background: Although the standard 1Radial and 1Ulnar portals allow for visualisation of most of the trapezium articular surface, the proximity of these two portals can often make arthroscopic triangulation and visualisation of the most lateral capsule and joint surface challenging. Despite its already reported advantages in improving visualisation, there is little literature reporting the clinical experience with the Thenar Portal. The purpose of this study is to describe potential complications and the short-term clinical-radiographic outcomes of arthroscopic hemitrapeziectomy using the Thenar Portal in order to determine its safety and efficacy as a standard working portal.

Patients and methods: A retrospective chart review was conducted for all patients diagnosed with first carpometacarpal (CMC) osteoarthritis who were treated surgically with an arthroscopic hemitrapeziectomy. Only patients with stage II or III osteoarthritis and a minimum of 1-year follow-up were included. Twenty-two patients (24 thumbs) with an average age of 62 years met the inclusion criteria. The average follow-up was 52 months. Intra-operative and post-surgical complications were recorded. Objective evaluation consisted of an assessment of range of motion (ROM), grip and pinch strength. Subjective evaluation consisted of a DASH questionnaire and the visual analog scale to score pain at rest, during activities, and function.

Results: There were no intra- or post-surgical complications. In one case, pain persisted with a poor functional result, requiring a revision surgery. Average range of motion (compared with the contralateral) showed a statistically significant improvement in palmar abduction and radial abduction of the CMC joint: 50° vs. 55° (p=0.01235), and 50° vs. 55° (p=0.06009), respectively. There was no statistically significant improvement in thumb adduction, grip strength, or lateral and tip-pinch. All patients achieved retropulsion with their affected thumb. According to the VAS, average rest pain improved from 7.5 to 0 (p<0.001) and from 9 to 0 (p<0.001) during activity. The average final function and QuickDASH were 9 (VAS) and 8, respectively (p<0.001). The average radiographic proximal migration of the first metacarpal was 2.9mm (range: 0.7-5.8mm).

Discussion: Arthroscopic hemitrapeziectomy using the Thenar portal: 1) improved visualisation of the trapeziometacarpal joint, 2) facilitated arthroscopic triangulation, and 3) represents a safe and effective alternative for the treatment of thumb osteoarthritis, with pain relief and function improvement in most patients without a higher risk of complications.

Level of evidence: IV.