Review Question - QID 219810

This 82-year-old female presents with right thumb metacarpophalangeal joint osteoarthritis that is recalcitrant to nonoperative treatment. The most appropriate surgical management includes thumb arthrodesis of the MCPJ in 20 degrees of flexion and slight pronation (Answer 2).

Metacarpophalangeal joint (MCPJ) osteoarthritis of the hand is an uncommon entity, estimated between 1 and 5% with a predilection for males. Primary osteoarthritis is more often seen in males, while females more routinely experience the condition associated with inflammatory arthropathies. The propensity for the condition to necessitate surgical intervention is somewhat high, and two options essentially exist for the condition: arthroplasty or arthrodesis. The latter serves as the mainstay for thumb MCPJ osteoarthritis, as the forces subjected across the joint vary greatly, making arthroplasty challenging. Furthermore, the majority of motion comes from the carpometacarpal joint, making arthrodesis easily tolerated (of note, this contrasts with other finger MCPJ arthritis, where arthroplasty is preferred). While many methods exist for performing thumb MCPJ arthrodesis (k-wires, plates, intramedullary screws), placing the thumb in 20-25 degrees of flexion with slight pronation positions the thumb in an ideal position for pinching.

Dr. Rizzo reviews MCPJ arthritis, examining the currently available non-operative and operative treatments. The condition has been decreasing in incidence, given the advent of biologic medications for inflammatory arthropathies. Nonetheless, those with primary and inflammatory arthritis continue to undergo surgical intervention. The author notes arthrodesis to be superior for pain relief, however, pyrocarbon and silicone arthroplasty are preferred for MCPJ arthritis of the index through small fingers. The author concludes arthrodesis is best for MCPJ of the thumb, while for the index through small fingers, more-constrained silicone implants are ideal for those with significant erosion or deformity and non-constrained pyrocarbon is suitable for milder disease without deformity.

Saldana et al. examined 100 patients (50 males and 50 females; 200 thumb MCPJ) in 13 different thumb positions to determine the optimal position for arthrodesis as the treatment for thumb MCPJ arthritis. The authors noted a high degree of variability concerning motion between both sexes, but found the average motion for males in all thumb directions was approximately 23 degrees for males, and 19 degrees for females. The authors concluded that 25 and 20 degrees of joint flexion is appropriate for men and women, respectively, but also note that comparing the diseased thumb to the contralateral thumb (assuming disease-free), provides the best information for ideal thumb positioning.

Figures A & B represent orthogonal views of the thumb illustrating severe osteoarthritis of the thumb MCPJ with palmar subluxation of the proximal phalanx. Of note, there is diffuse osteoarthritis throughout the other finger PIP and DIP joints.

Incorrect Answers:
Answers 1, 3, 4, and 5: these positions do not put the thumb in an advantageous position for function following arthrodesis.