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CMC Joint / CMC Arthritis

- See:
- CMC Joint Instability
- Trapezium
- Ligament Reconstruction Tendon Interposition

- Anatomy of CMC
- Arthritis of CMC Joint:
- most commonly involved arthritic joint in the hand;
- more common in women (upto 1/3 of women over age 40, will have x-ray changes);
- may exist in a localized form or may exists as a systemic form of arthritis;
- primary form is most common in post-menopausal women;
- systemic form may be due to RA or gout;
- in the report by Moulton MJR, et al (2001), the authors propose that a hypermobile MP joint may have a causative role in the development of
primary OA at the base of the thumb by concentrating forces on the palmar aspect of the trapeziometacarpal joint;
- in specimens affected by DJD, center of pressure on CMC joint moved dorsally by 56.8% of the length of the trapezial surface
with MP joint flexions of 30° (p < 0.01), vs 28.2% and 40.9% in the hyperextended and neutral MP joint positions, respectively;
- in specimens with moderate osteoarthritis, 30° of MP joint flexion also produced most dorsal trapeziometacarpal center of pressure (44.8%);
- however, this center of pressure was not significantly different from the centers of pressure at the other MP joint positions.
- in nonarthritic specimens, the center of pressure was again significantly more dorsal with MP joint flexion of 30° than it was at the other positions (p < 0.01).
- MP joint flexion effectively unloaded the most palmar surfaces of the trapeziometacarpal joint regardless of the presence or
severity of arthritic disease in this joint;
- presence of hyperextension laxity of the MP joint may identify pts who are predisposed to the development of arthritis of CMC joint;
- may benefit from early intervention to stabilize the MP joint and retard natural progression of OA disease at the base of the thumb;
- in symptomatic patients with a hypermobile MP joint, fixation of the MP joint in flexion by either splinting or surgical stabilization may
alleviate basal joint symptoms by redirecting trapeziometacarpal joint forces away from the palmar compartment and onto
the healthier dorsal aspect of the joint;
- references:
- Influence of Metacarpophalangeal Joint Position on Basal Joint-Loading in the Thumb
- Osteo-arthritis in the first carpo-metacarpal joint; an investigation of 22 cases.
- Osteoarthritis at the base of the thumb.
- Carpometacarpal arthritis of the thumb.
- Osteoarthritis of the trapeziometacarpal joint: the pathophysiology of articular cartilage degeneration. I. Anatomy and pathology of the aging joint.
- Osteoarthritis of the trapeziometacarpal joint: the pathophysiology of articular cartilage degeneration. II. Articular wear patterns in the osteoarthritic joint.
- Degenerative joint disease of the trapezium: a comparative radiographic and anatomic study.
- differential dx: (see: radial sided wrist pain)
- deQuervain's tenosynovitis;
- FCR tendinitis;
- stenosing flexor tenosynovitis of FPL;
- associated disorders:
- carpal tunnel syndrome: may be present in upto 28% of patients;
- deQuervain's tenosynovitis: may be present in 5%;

- Physical Exam:
- axial compression of metacarpal on trapezium gives painful grinding sensation;
- attempt to determine whether pain is related to instability vs arthrosis;
- thumb may have adduction deformity (web space contracture)
- hyperextension deformity of MCP joint often follows adduction contracture;
- localized tenderness over volar aspect of thumb;
- no triggering during thumb flexion;
- no pain w/ forced wrist flexion;
- when in doubt, a small amount of local anesthetic injected into CMC joint w/ a resolution of pain will confirm the dx;

- Classification:
- Stage I:
- mild joint narrowing or subchondral sclerosis;
- mild joint effusion or ligament laxity;
- no subluxation and no osteophyte formation are present;
- treatment involves NSAIDS & immobilization (which involves splinting the thumb in abduction);
- Stage II:
- narrowing of CMC joint & sclerotic changes of subchondral bone;
- there may be osteophyte formation at the ulnar side of the distal trapezial articular surface;
- mild to moderate suluxation may be present (w/ the base of the first metacarpal subluxated radially and dorsally);
- treament: ligament reconstruction tendon interposition:
- Stage III:
- furthere joint space narrowing w/ cystic changes and sclerotic bone;
- prominent osteophytes are present at the ulnar border of the distal trapezium;
- moderate suluxation is present w/ the base of the first metacarpal subluxated radially and dorsally;
- passive reduction may not be present;
- scaphotrapezial may show arthrosis, and there may be a hyper-extension deformity of the MTP joint;
- treament: LRTI;
- Stage IV:
- there is similar destruction as in stage III w/ respect to CMC;
- scaphotrapezial joint has evidence of destruction;
- CMC joint is usually immobile and often patients have little pain;
- treament options: LRTI;
- Trapeziometacarpal osteoarthritis. Staging as a rationale for treatment.
- Interobserver Agreement of the Eaton-Littler Classification System and Treatment Strategy of Thumb Carpometacarpal Joint Osteoarthritis

- Surgical Options:
- Trapezium Excision
- CMC Fusion:
- most indicated for painful instability (especially w/ sytemic hyperlaxity), and indicated for a young active male w/ isolated CMC arthrosis (and absence of arthrosis in adjacent joints);
- thumb metacarpal is held in 30-40 deg palmar abduction and 10-15 deg of radial abduction;
- disadvantages:
- may predispose to pain and/or arthrosis of adjacent joints;
- significantly high rate of non union (upto 50%)
- need for prolonged postoperative casting;
- references:
- Trapeziometacarpal joint arthrodesis: a functional evaluation.
- Arthrodesis of the carpometacarpal joint of the thumb. A review of patients with a long postoperative period.
- Prosthetic Replacement:
- main problem is instability and dislocation of prosthesis (may occur in 40 % of thumbs);
- references:
- Use of the Swanson Silicone Trapezium Implant for Treatment of Primary Osteoarthritis. Long-Term Results
- Trapeziometacarpal total joint replacement using the Steffee prosthesis.
- Long-term complications of trapeziometacarpal silicone arthroplasty.
- Prospective 1-year follow-up study comparing joint prosthesis with tendon interposition arthroplasty in treatment of trapeziometacarpal osteoarthritis.

Surgical Treatment of Trapeziometacarpal Arthrosis. Thompson JS. Adv Orthop Surg. 1986:105-118.

Trapeziometacarpal-I--Symposium: The Basal Joint Pain Syndrome.

Hematoma and distraction arthroplasty for thumb basal joint osteoarthritis: a prospective, single-surgeon study including outcomes measures.

Basal joint arthroplasty and carpal tunnel release through a single incision: an in vitro study.