Fractures of the Proximal Ulna in Dogs

Abstract

SummaryIn a retrospective study of fractures of the proximal ulna in dogs, 22 cases were identified over a 12-year period. Follow-up data was available for 13 dogs. Fractures of the proximal ulna were often comminuted, and most commonly had an intra-articular component affecting the ulnaro-humeral joint. Common causes included: motor vehicle trauma and falls from a height. Blunt thoracic trauma and additional orthopaedic injuries were often seen with the more severe types of fractures.Healing of intra-articular proximal ulnar fractures usually occurred after anatomical reconstruction and rigid internal fixation. Secondary osteoarthritis was minimal. The pin and tension band technique gave satisfactory results for simple non-articular fractures of the olecranon, but for intra-articular fractures this fixation method was associated with a greater incidence of complications such as: implant breakage, delayed union and infection. Implant loosening or breakage and delayed union were not observed, when fracture fixation with bone plates placed on the caudal or lateral aspects of the ulna was performed. Localized infection associated with a bone plate was identified in one of 10 patients and plate removal was carried out after the fracture had healed.Fractures of the proximal ulna in 13 dogs were frequently intra-articular and comminuted. Most fractures stabilized with tension band fixation or a small bone plate on the caudal surface of the ulna healed with minimal secondary osteoarthritis. However, complications with tension band fixation were common.

Biomechanical Comparison of Dual Interlocking Single Loop and Double Loop Tension Band Techniques to the Classic AO Tension Band Technique for Repair of Olecranon Osteotomies in Dogs

“…Rotation of the proximal olecranon segment during mechanical testing has not been described in the human or veterinary literature to our knowledge 5–12,15–34 . We observed this movement frequently as the constructs began to fail.…”

“…However, a critical review of the radiographic images included in many of these articles suggests that the construct is not always formed optimally. Common errors observed included the orthopedic wire not contacting the proximal bone fragment and/or the K‐wires, the twist knots being bent‐over (which reduces wire tension), the distal ulnar hole too far from the osteotomy, or the K‐wires not being placed perpendicular to the osteotomy 7,8,10,12,15–17 . Therefore, we decided to add another arm to the study and place the classic AO TBW constructs incorrectly, by positioning the wire so that it did not contact the bone or K‐wire.…”

“…Complications associated with TBW repair include migration of the K‐wires, osteomyelitis, malalignment of articular surfaces, nonunion, delayed union, comminution of the fracture fragment during implant placement, pain associated with loose or improperly placed implants, implant breakage and neurapraxia 5–11 . A retrospective study of 100 human cases reported satisfactory results with TBW for olecranon fracture repair but recommended plate fixation in complicated fractures (e.g., comminuted intraarticular fractures) 3 .…”

“…A common mode of failure of the TBW in repair of olecranon osteotomy is unwinding of the wire twists, with subsequent wire breakage 5–11 . Previous studies of cerclage wire have shown that the double loop (DL) and loop‐twist knots generate superior tension and resist greater load when compared with a twist knot 13 .…”

Fractures of the Radius and Ulna

“…A Robert-Jones dressing may be indicated for temporary additional support. 10 This is especially true for large and giant breeds of dogs. For best results, this pull should be neutralized by use of the tension band principle.…”