Single Cortical Positional Screw for Fixation of a Fibular Head Instability: A Case Report

Fibular head instability and avulsion fractures are rare as isolated injuries in veterinary medicine, with no case reports to date. The fibular head is anatomically secured in location proximo-distally by the lateral collateral ligament, and craniocaudally by the cranial and caudal fibular head ligaments, respectively. Due to the location of the fibular head prominent to the lateral stifle, it is hypothesized that a forceful impact or a torsional force could result in the avulsion of the cranial and caudal fibular head ligaments without causing other stifle pathology. A 1-year-old, 26 kg, spayed female Border Collie mix was referred for evaluation of chronic bilateral SH-II tibial tuberosity avulsion fractures. The patient had a nonweight-bearing lameness of the right pelvic limb and no left pelvic limb lameness. The tibial tuberosities palpated comfortably and stable, with pain isolated on examination to the right fibular head, with approximately 2 mm craniocaudal mobility appreciated on examination. The contralateral stifle palpated normal. Preoperative flexion and extension radiographs confirmed stable tibial tuberosities bilaterally with evidence of physeal closure. There was no fibular pathology radiographically. Intraoperatively the cranial and caudal fibular head ligaments were diagnosed completely torn, with the lateral collateral ligament remaining intact. Open reduction and stabilization of the right fibular head was performed with a 2.7 mm cortical positional screw placed bicortically from the fibular head to the proximal tibia. No postoperative external coaptation was placed. At an 8-week follow-up, the dog exhibited no signs of lameness at walk, and only a slight intermittent “hitch” at the end of the gait cycle at trot as described by the owner. Radiographs showed no implant-associated complications. Implant removal was offered, however not pursued. Attempts to contact the owner for further updates were unsuccessful. This case report documents the successful surgical treatment of fibular head avulsion in a dog using a single cortical positional screw technique.

Acknowledgment

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Publication History

Article published online:
15 July 2025