Obwegeser cerclage technique for the treatment of jaw fractures in horses: a retrospective study on 46 cases (1987–2010)

Abstract

Skull fractures, particularly mandibular fractures, are the second most common fractures in horses after limb fractures. The majority of mandibular fractures involves its most rostral part, i.e. the pars incisiva. Like other head fractures, those of the jaws are commonly caused by a blunt external trauma such as a kick from another horse, a fall or a collision with a solid object. Rostral fractures can also occur when horses get caught between vertical metal bars in the stall: the horse bites the bar with its head tilted towards a slightly horizontal position and then suddenly pulls back its head together with a vertical movement of the head, while the teeth remain lodged between the metal bars. In rare cases jaw fractures occuriatrogenically following dental treatment or due to pathological alteration of the bone in case of neoplasia or chronic osteomyelitis. In the majority of cases jaw fractures are open toward the oral cavity and may be severely contaminated. Unstable, bilateral or dislocated fractures which lead to impaired occlusion need surgical intervention. Intraoral wiring is one of the fixation techniques used, depending on the fracture configuration. The Obwegeser multiple-loop intraoral wiring method is particularly suited for fixation of avulsion fractures of the incisors because teeth can be fixed individually, the tension can be distributed evenly among different teeth and the fixation can be extended across a wide area. This method is very suitable for fixation of rostral jaw fractures. It can also be used in combination with other fixation techniques, e.g. plate osteosynthesis, to provide additional stability on the tension side of a fractured mandible and incisor bone. This retrospective study examined 46 patients with jaw fractures that were fixed using the Obwegeser wiring method alone (n=31) or in conjunction with another fixation method (n=15). Medical records, repeated radiological examinations and telephone interviews with the owners were used to gather information about clinical signs on presentation, type of fracture fixation, the healing process, short and long term complications, time of removal of the wires and owner satisfaction with the surgical outcome. The following clinical signs were found with the initial examination: oral haemorrhage (n=28), dysphagia (n=24) and local swelling (n=21). 23 horses suffered from malocclusion and in 5 of 46 patients crepitation was obvious. In 20 cases (43%) the fracture was older than 24 hours at the time of presentation to the hospital. Forty (87%) of the fractures were open. Cases that were fixed using the Obwegeser wiring method alone had a lower complication rate (11/31, 35%) than cases in which wiring was used in conjunction with another fixation method (12/15, 80%). In most cases the fracture could be repaired in the standing horse using sedation and local anaesthesia. An orthopaedic stainless steel wire with a diameter of 1.25 mm was used for cerclage. Wires used alone were left in place for an average of 10 weeks (mean 10.0 and SD±5.8) and those used in addition to another fixation method for an average of 16 weeks (mean 16.0 and SD±8.9). No further complications associated with the fracture occurred in 31 (93%) of the 33 cases that had long-term follow-up information. The fact that in 20 cases (43%) the fracture was older than 24 hours at the time of presentation to the hospital shows that jaw fractures are commonly not recognized immediately or are underestimated by owners or referring veterinarians. The lower complication rate in the 31 cases treated with the Obwegeser wiring method alone may be explained by the lower complexity of the fractures, the intra- versus the extraoral position of the implants and thereby no possible interference of the implant with fracture healing, and the reduced amount of implant material. This study shows that the inexpensive and relatively simple Obwegeser method is a very suitable method for fixation of rostral jaw fractures in the horse.