Surgical Repair of Luxation of the Superficial Digital Flexor Tendon in Dogs Using a Calcaneal Chondroplastic-like Technique—Three Cases

SIMPLE SUMMARY: Luxation of the superficial digital flexor (SDF) tendon is an infrequent orthopedic condition in dogs. The rupture of the medial or lateral retinacular insertion of the SDF on the calcaneal tuberosity allows the tendon to luxate laterally or medially, respectively. Obesity, microtrauma, torsional forces, and morphological abnormality of the calcaneus are predisposing factors and, in particular, a shallow surface to the calcaneal tuberosity as a consequence of underdeveloped medial or lateral processes. To date, surgical treatments have not focused on the correction of any detected anatomical defect of the shape or size of the calcaneal tip but on repairing and reinforcing the damaged retinaculum. The purpose of this report is to describe the technique and the clinical outcome of dogs with SDF tendon luxation treated using a calcaneal chondroplastic-like technique. This surgery helped to accommodate and stabilize the SDF tendon in the calcaneal groove. This treatment showed excellent short- and long-term outcomes, without signs of re-luxation and lameness during follow-ups. These preliminary data show that calcaneal chondroplasty associated with retinaculum repair might be a valid option for the treatment of luxation of the SDF tendon. Further studies are required to determine the real success of the surgical technique proposed in this report. ABSTRACT: The purpose of this report is to describe the technique and the clinical outcome of three dogs affected by superficial digital flexor (SDF) tendon luxation treated using a calcaneal chondroplastic-like technique. A German Pinscher with bilateral and lateral SDF tendon luxation, a Griffon Nivernais with medial SDF tendon luxation following self-mutilation of the IV toe, and an American Staffordshire Terrier with a lateral luxation and having undergone calcaneal chondroplasty and primary repair of the retinacular tissues. A fibrocartilage flap covering the calcaneal groove was elevated, the subchondral bone was removed from beneath it, and the flap was pressed back into the deepened sulcus, keeping its distal attachment as a hinge point. The SDF tendon was reduced, and its tracking along the deepened groove was ensured. Furthermore, the torn retinacular attachment was repaired. Clinical follow-ups at 4 and 8 weeks and 1 year apart showed no signs of lameness and no SDF tendon re-luxation. The calcaneal chondroplastic-like technique led to a satisfactory outcome with no complications. This technique is relatively straightforward, requires no implants, and is also successful without postoperative immobilization of the tarsal joint. Further cases are required to determine its benefits and its risks compared to conventional surgery.