- Discussion:
    - rupture of the flexor pollicis longus tendon is common in RA;
    - etiology:
         - rupture of FPL occrus as result of attrition over scaphoid (osteophyte), which had eroded through volar wrist capsule;
         - arises from carpal irregularities, volar synovitis, or volar carpal tunnel subluxation at the carpal tunnel;
    - diff dx:
         - anterior interosseous nerve;
         - trigger thumb
         - IP joint arthritis;

- Exam:
    - carefully note anterior interosseous nerve function (r/o compression);
    - carpal tunnel symptoms may result from proximally displaced tendon edge which has been known to be doubled over itself at entrance of carpal tunnel;
    - patients typically have passive but not active flexion of thumb at IP joint (otherwise consider trigger thumb);
    - if pt has a good IP joint, then the loss is apparent;
    - if there is destruction of the IP joint then the tendon rupture causes little functional loss;

- Radiographs:
    - assess amount of joint destruction of IP, MP, and CMC joints;
    - carpal tunnel view

- Treatment:
    - FPL Advancement and Pull Through:
    - either terminal joint stability or restoration of active motion must be provided;
    - volar aspect of wrist must be explored, to look for a bony spicule that has disrupted
          FPL, since such a spicule might also affect the tendons of the index finger;
    - treatment options include FPL advacement and pull thru, bridge grafts, FDS tendon transfer, or arthrodesis  of PIP joint & synovectomy;
    - if spicule of bone is present, and both ends of the tendons can be identified, then consider a bridge graft;
          - use palmaris longus or FCR;

- Post Op:
    - the thumb and wrist are immobilized for three weeks, before active motion is begun

Flexor superficialis tendon transfers to the thumb: An alternative to the free tendon graft for treatment of chronic injuries within the digital sheath.