Tendon Injuries

Flexor Tendon Injuries

Background

• Relevant anatomy
• Each finger has 2 flexor tendons while the thumb has one flexor tendon
• FDS (Flexor Digital Superficialis) flexes the PIPJ (Proximal Inter-phalangeal joint)
• FDP (Flexor Digital Profundus) flexes the DIPJ (Distal Inter-phalangeal joint)
• Synovial sheath surrounding the tendons
• Fibro-osseous tunnel encloses the synovial sheath
• Tunnel consists of 5 thickened annular (A) bands and 3 cruciform (C) pulleys
• A2 and A4 pulleys most important in preventing bow stringing of flexor tendons
• Diagnosis depends on whether one or both tendons are involved and whether the flexor tendons are within or outside the tendon sheath at the point of injury