Metacarpophalangeal joint synovectomy, crossed intrinsic tendon transfer, and extensor tendon centralization

Indications

Crossed intrinsic tendon transfer is indicated in patients with ulnar subluxation of the extensor tendon and passively correctable ulnar deviation of the digits because of rheumatoid arthritis (RA) or traumatic radial sagittal band rupture. The metacarpophalangeal (MCP) joint must be supple and without significant arthritic changes or subluxation.
In RA patients, the index finger ulnar common intrinsic tendon is transferred to the extensor digitorum communis (EDC) of the long finger; the long finger tendon is used to correct the ring finger; and the ring finger tendon is used for the small finger. Ulnar deviation of the index finger is corrected, imbricating the radial sagittal band.
The crossed intrinsic transfer corrects ulnar deviation by decreasing ulnar force on the donor digit and increasing radial force on the recipient digit.

Contraindications

For patients with significant MCP joint subluxation or arthritis, soft tissue reconstruction does not adequately stabilize a severely subluxated proximal phalanx. These patients should undergo silicone MCP arthroplasty (see Chapter 41 ).

Clinical examination

Clinical examination focuses on the condition of the MCP joint and the position of the extensor tendon.
Synovitis presents as swelling over the dorsal MCP joint ( Fig. 36.1 ). Synovitis can lead to attenuation of the sagittal bands, volar subluxation of the proximal phalanx, ulnar drift of the fingers, or tendon rupture.
In RA patients, the extensor tendons often subluxate ulnarly and lie in the intermetacarpal space. This is obvious when the patient makes a fist ( Fig. 36.2 ).
Active and passive range of motion (ROM) is measured. When a patient is unable to actively extend the MCP joints, it is important to distinguish between tendon subluxation and tendon rupture. The examiner passively extends the MCP joints; if the tendon is intact but subluxated, the patient can maintain extension. If the tendon is ruptured, the MCPs fall into flexion when the examiner’s hand is removed.
Intrinsic tightness can occur with chronic ulnar deviation at the MCP joint. Check for intrinsic tightness by extending the MCP joint and flexing the proximal interphalangeal (PIP) joint. In patients with intrinsic tightness, PIP joint flexion will be restricted with the MCP extended and will improve when the MCP is flexed.