Outcomes of Arthrodesis of the Metacarpophalangeal Joint of the Thumb for Sequelae of Collateral Ligament Injuries: A Series of 18 Cases with 6-Year Follow-Up.

Background: Untreated or insufficiently treated collateral ligament injuries of the thumb metacarpophalangeal (MP) joint can lead to instability or even osteoarthritis. Arthrodesis is one of the treatment options available for the treatment of the sequelae of collateral ligament injuries. The objective of our study was to evaluate the radiological, clinical and functional outcomes of MP joint arthrodesis performed for sequelae of collateral ligament injuries. Methods: We conducted a retrospective, single-centre study and reviewed the files of patients who had a thumb MP joint arthrodesis following a collateral ligament injury between 2011 and 2019. We collected patient's demographic data and the results of the radiological and clinical examinations. Results: Eighteen patients were included in the study. The average age was of 53.6 years and the time between injury to arthrodesis averaged 7 years. Four patients (22%) had nonunion. In the remaining 14 patients with solid union at an average of 72 months follow-up, the visual analogue pain score at rest was 0.14, the thumb opposition was 82%, grip strength 85%, tip pinch 92% and key pinch 79% of the contralateral side. Conclusions: The clinical and functional results of patients with a successful arthrodesis are satisfactory with restoration of good grip and pinch strength. Despite a lack of thumb MP joint flexion, stability allowed force transmission and may be preferred for manual workers. Level of Evidence: Level IV (Therapeutic).

Influence of the anatomy of the proximal articular surface of the trapezium (PAST) and the trapezoidal articular surface of the trapezium (TRAST) in cup placement during trapeziometacarpal arthroplasty.

The influence of the anatomy of the proximal articular surface of the trapezium (PAST) and the trapezoidal articular surface of the trapezium (TRAST) on cup placement during trapeziometacarpal arthroplasty was retrospectively evaluated on 56 preoperative anteroposterior radiographs of patients who underwent surgery for trapeziometacarpal osteoarthritis. The percentage coverage of the prosthetic cup by the PAST and the available height of the trapezium were calculated. In 39% of cases, there was a significant difference (up to a mean 4.5 mm, p < 0.001) between the radial height of the trapezium (which is usually considered) and the available height of the trapezium. The anatomy of the PAST and the TRAST has an impact on the placement of the prosthetic cup when trapezium height is low. The results of the present study suggest that these considerations must be known by all operators performing trapeziometacarpal arthroplasty; that lateralization, implant suspension, or surgical alternatives should be considered to prevent several intra- and postoperative surgical complications. Level of evidence: IV.