In vitrobiomechanical evaluation of internal fixation techniques on the canine lumbosacral junction

Abstract

Few biomechanical studies have evaluated the effect of internal stabilization techniques after decompressive surgery on the stability of the canine lumbosacral junction. The purpose of this canine cadaver study is to evaluate the stability of the canine lumbosacral (LS) spine in flexion and extension following laminectomy and discectomy and then stabilization with each of the three techniques: pins and polymethylmethacrylate (P/PMMA), two dorsal locking plates (SOP) or bilateral transarticular facet screws (FACET).Using a cantilever biomechanical system, bending moments were applied to the LS and range of motion (ROM) was recorded via a rotational potentiometer. With 3 Nm, the ROM (n = 4 in each group) for P/PMMA, SOP and FACET were 1.92 ± 0.96°, 2.56 ± 0.55°and 3.18 ± 1.14°, respectively. With moments up to 35 Nm, the P/PMMA specimens appeared stable. Sacroiliac motion in the SOP and FACET groups invalidated further comparisons. Each of the stabilization techniques (P/PMMA, SOP, and FACET) significantly decreased the range of motion in flexion and extension for low bending moments.

Accuracy and Efficacy of a Patient-Specific Drill Guide Template System for Lumbosacral Junction Fixation in Medium and Small Dogs: Cadaveric Study and Clinical Cases

“…All three cases were diagnosed as luxation of the lumbosacral junction. One case showed chronic progressive paraparesis and ataxia, which were thought to result from spinal instability based on imaging findings of degenerative changes, such as intervertebral disc degeneration, and spondylosis deformans (2,9,(18)(19)(20). The other two cases were diagnosed as spinal instability due to trauma, based on imaging findings of lumbosacral luxation.…”

“…Although this condition is most commonly seen in medium-and large-sized dogs, it can also be seen in small dogs, typically presenting with caudal lumbar back pain (1). Lumbosacral luxation in small animals usually result from trauma such as hitting by car or falling from high place, when external forces overwhelm the physiological stabilizers of spine (2).…”

“…Surgical treatment for DLSS is the standard choice of treatment in the presence of severe caudal lumbar pain or neurologic deficits that do not respond to conservative therapies (3,4). The reported surgical techniques for DLSS include dorsal laminectomy alone or in combination with partial discectomy, dorsal laminectomy combined with fixation and fusion, or lateral foraminotomy (2,3,(5)(6)(7)(8). Although the reported rate of short-term improvement of clinical signs with decompressive surgery is as high as 78-93% (1,9), the longterm recurrence rate of clinical symptoms is also relatively high at 17-38% (1,9).…”

“…Fixation of the lumbosacral junction is commonly achieved by implants, such as pins and/or screws, placed within the pedicles or vertebral bodies along with polymethylmethacrylate (PMMA) (5,10,11), or by using a pedicle screw-rod fixation system (1,6,12,13). The advantage of dorsal fixation is that it provides stability to the lumbosacral junction and can reduce dynamic compression of the spinal cord (1,2,6). However, the placement of implants for lumbosacral junction fixation carries a potential risk of iatrogenic injury to vital structures including cauda equine, nerve roots, and vasculature (3).…”

Long-term clinical complications associated with the use of polymethyl methacrylate in spinal stabilization of dogs and cats: case series

“…Despite the small number of cases reported here, we observe that medium or long term complications may occur in the thoracolumbar spine secondary to the internal use of bone cement, with thinner muscle cover at the implant site compared to the cervical spine; this should be taken into consideration prior to surgery. In veterinary medicine, there are biomechanical studies comparing the efficacy and versatility of alternative methods of vertebral fixation like locking plates and pedicular screws with PMMA in the spine (Early, Mente, Dillard, & Roe, 2015;Lewchalermwong, Suwanna, & Meij, 2018;Sturges et al, 2016), which may have lesser complication rates and be easier to remove and substitute, if necessary.…”