Review Question - QID 215508

This patient has first carpometacarpal joint (CMCJ-1) osteoarthritis and a minor hyperextension deformity of the first metacarpophalangeal joint (MCPJ-1). Patients with minor MCPJ-1 hyperextension deformities (<30°) undergoing isolated CMCJ-1 reconstruction are expected to have similar functional outcomes compared to patients without any hyperextension deformity.

Carpometacarpal joint (CMCJ-1) osteoarthritis is thought to be due to attenuation of the anterior oblique (Beak) ligament. Instability ensues altering joint reaction forces leading to the development of OA. Hyperextension of the first metacarpophalangeal joint occurs to overcome the decreased abduction of the first metacarpal. While MCJP-1 arthrodesis remains the treatment of choice for severe deformities and concurrent MCPJ-1 OA, there remains no "gold-standard" or absolute indication in terms of the degree of deformity that necessitates a specific surgical procedure. Furthermore, there is no current evidence that has demonstrated significant improvement in patient outcomes with MCPJ-1 deformities <30°.

Brogen et al. evaluated functional outcomes in patients treated for CMCJ-1 arthritis. Patient were divided into two groups, those with mild but untreated pre-operative MCPJ-1 hyperextension (<30°) and those without MCPJ-1 hyperextension. None of the patients had procedures to address MCPJ-1 hyperextension. They found no statistically significant difference in the improvement of functional outcomes after surgery when comparing patients without preoperative MCPJ-1 hyperextension to patients with untreated MCPJ-1 hyperextension less than 30°.

Dumont et al. performed a biomechanical study using cadavers to assess changes in the transmission of forces at the thumb’s end phalanx following a trapeziectomy combined with the surgical adjustment of MCPJ-1 hyperextension. They concluded that combining trapeziectomy with surgeries addressing the MCPJ-1 hyperextension induced a shift of the thumb in pronation-abduction that could impair the key-pinch stability. Furthermore, they recommend fixing the EPB-tendon on the radial aspect of the metacarpal head if a tendon transfer is considered.

Poulter et al. investigated the management of MCPJ-1 hyperextension in 297 patients undergoing trapeziectomy for basilar thumb osteoarthritis. They reported no difference in 1-year clinical outcomes after trapeziectomy between patients with untreated preoperative MCPJ-1 hyperextension up to 45 degrees and those without preoperative MCPJ-1 hyperextension. They also found that surgical correction of preoperative MCPJ-1 hyperextension <30 degrees did not improve outcome.

Figure A is an x-ray demonstrating osteoarthritis isolated to the thumb carpometacarpal joint and a minor hyperextension deformity of the MCPJ-1. Illustration A demonstrates the Eaton and Littler classification of basilar thumb arthritis.

Incorrect Answers:
Answers 1-4: Patients with minor MCPJ-1 hyperextension deformities (<30°) undergoing isolated CMCJ-1 reconstruction are expected to have similar functional outcomes in terms of key pinch strength, grip strength, and range of motion compared to patients without any hyperextension deformity.