How to Perform a Modified Standing Deep Digital Flexor Tenotomy at the Level of the Proximal Interphalangeal Joint

1. Introduction
Horses with refractory acute and chronic laminitis can be difficult to treat. Veterinarians trying to manage these cases have three common objectives: (1) alleviate the pain associated with laminitis, (2) establish a more normal relationship between the distal phalanx and the hoof capsule, and (3) support the distal phalanx to prevent further alterations in its orientation within the hoof capsule (i.e., rotation or distal displacement). Medical and surgical therapies, including non-steroidal anti-inflammatory agents, peripheral vasodilators, hemorheologic agents, icing the feet, corrective shoeing, and deep digital flexor (DDF) tenotomy, are used extensively to treat horses with refractory laminitis.^1–5  Despite these treatment options, successful treatment of difficult laminitic cases is not always feasible.

Tenotomy of the DDF may be performed either in the mid-metacarpus or at the level of the proximal interphalangeal (PIP) joint.^1,3  Regardless of the site, the purpose of the tenotomy procedure is to remove the force that is primarily responsible for rotation of the distal phalanx and pain associated with the laminar separation.^1,6  In the original description of the DDF tenotomy, a 3-cm vertical incision was made on the palmar aspect of the flexor tendon sheath at the level of the PIP joint. The surgery was performed with the horse under general anesthesia with the limb surgically prepared and draped to maintain a sterile environment.¹  Subsequently, a DDF tenotomy procedure was developed in which the surgery was performed in the mid-metacarpus with the horse standing.3 Because of the ease of the latter procedure and the fact that it did not require general anesthesia, the midmetacarpal tenotomy has been widely used in treating horses with laminitis. [...]