Outcomes and Complications Associated With Ventral Screws, Pins, and Polymethyl Methacrylate for Atlantoaxial Instability in 12 Dogs

Abstract

Clinical outcomes and complications of a technique used for atlantoaxial stabilization were evaluated in a group of 12 dogs. At surgery, the atlantoaxial joint was realigned and rigidly fixated using cortical bone screws, K-wire, and polymethyl methacrylate. Results in nine dogs were graded as excellent. Results in two dogs were judged as good. One dog was euthanized 17 months after surgery for recurrent cervical pain. Eight dogs had no postoperative complications. The surgical technique described provided an adaptable method for the correction of atlantoaxial instability.

Atlantoaxial subluxation

“…It will also reveal abnormal dens conformation, which is seen in over 70% of dogs (Denny et al, 1988;Beaver et al, 2000) (9.6). An MRI (9.7) might prove to be prognostic if there is extensive spinal cord malacia and it will also reveal syringohydromyelia (Sanders et al, 2000) (9.12). …”

Biomechanical evaluation of three ventral fixation methods for canine atlantoaxial instability: a cadaveric study

“…Currently, the former is widely used because the success rate of the surgery is high, and the necessity for re-operation and surgery-related mortality rate are low [2, 3, 6, 9, 13, 22, 24, 34]. In addition, because the articular cartilage of the AAJ is removed and a cancellous bone is grafted during ventral fixation, bone fusion might be promoted with this approach [4, 9, 22, 24]. In the ventral approach, after reduction of the subluxated AAJ, the odontoid can be removed under visual inspection, if necessary.…”

“…In the ventral approach, after reduction of the subluxated AAJ, the odontoid can be removed under visual inspection, if necessary. Stabilization of the AAJ is performed using a transarticular fixation (TAF) method that employs bone screws or positively threaded profile pins (PPP), using a supportive fixation method that employs bone screws, PPP and polymethylmethacrylate (PMMA), or employs PPP and PMMA, and using a plate fixation method, with the final goal being bony fusion of the AAJ [1, 2, 7, 9, 16, 17, 21,22,23,24,25,26, 28,29,30,31, 35]. Stabilization from the ventral aspect is an established surgical procedure, which is a widely used surgical method.…”

Computed tomography, magnetic resonance imaging and a novel surgical approach of atlanto-axial instability with incongruence in dogs

“…Thus, in cases where the AA articulation is incongruent, such compression can lead to an exacerbation of basilar invagination, or the displacement of the atlas and the axis toward the foramen magnum. Moreover, each described technique is prone to possible complications such as post-operative dyspnoea, permanent respiratory signs, laryngeal paralysis, recurrence of cervical pain, ataxia, Horner's syndrome, and/or migration of the transarticular pins [24].…”

“…In fact, considering literature data regarding the treatment of AA instability in toy breeds, conservative options and several surgical stabilisation techniques are described [1,2,10,12,13,15,19,26]. Standard surgical treatment consists of ventral arthrodesis with cross pinning, transarticular lag screw fixation or vertebral plating [1,12,19,21,24]. This technique requires AA joint congruence, otherwise the means of synthesis can injure the spinal cord [27].…”