A Flexure Deformity can be defined as a condition in which the distal interphalangeal (DIP) joint or (less frequently) the metacarpophalangeal joint is held in flexion by a shortening of the musculotendinous unit.

“Contracted tendons,” the term traditionally used when referring to this condition, is a misnomer since tendons lack the ability to contract. The primary defect is a shortening of the musculotendinous unit rather than a shortening of the tendon portion, making “flexure deformity” the preferred descriptive term.

This shortening of the musculotendinous unit produces a structure of insufficient length for normal limb alignment and results in variable clinical signs such as an upright pastern angle, club feet or the severe flexural deformity described in this case report.

Anatomy Review

The musculature of the deep digital flexor (DDF) tendon lies directly on the caudal aspect of the radius (forearm) and is covered by the superficial digital flexor tendon and the flexors of the carpus (knee). It consists of three muscle bellies (the humoral head, radial head and ulnar head) which form a common tendon just above the knee.

This tendon, along with the superficial digital flexor tendon, passes through the carpal canal and continues down the palmer aspect of the limb. The deep digital flexor (DDF) tendon perforates the tendon of the superficial digital flexor tendon below the fetlock and inserts on the palmer surface of the third phalanx (P3).

A strong tendinous band known as the inferior check ligament originates from the deep palmer carpal ligament and joins…