Randomized Multi-Center Post Market Clinical Study to Evaluate the Safety and Performance of NextraTM for Use in Foot Surgery to Fuse the Proximal-interphalangeal- Joints

Hammertoe deformity is the most common deformity of the lesser toes. It primarily comprises flexion deformity of the proximal interphalangeal (PIP) joint of the toe, with hyperextension of the metatarsophalangeal (MTP).

Etiologies of hammertoe deformity include a foot in which the second ray is longer than the first, MTP synovitis and instability, inflammatory arthropathies, neuromuscular conditions, and ill-fitting shoe wear. When a foot's second ray is longer than the first and shoe wear does not fit correctly, flexion of the PIP joint occurs to accommodate the shoe. This length difference also causes MTP synovitis to develop from overuse of the second MTP joint. Attenuation of the collateral ligaments and plantar plate result, and the MTP joint hyperextends and may even progress to dorsal subluxation or dislocation (see image below). Rheumatoid arthritis causes hammertoe deformity by progressive MTP joint destruction, leading to MTP joint subluxation and dislocation.

With all 3 of these etiologies, the extensor digitorum longus (EDL) tendon gradually loses mechanical advantage at the PIP joint, as does the flexor digitorum longus (FDL) tendon at the MTP joint. The intrinsic muscles fire and sublux dorsally, as the MTP hyperextends. They now extend the MTP joint and flex the PIP joint, as opposed to their usual functions of flexing the MTP joint and extending the PIP joint.