Degenerative changes of the canine cervical spine after discectomy procedures, an in vivo study

Abstract

BackgroundDiscectomies are a common surgical treatment for disc herniations in the canine spine. However, the effect of these procedures on intervertebral disc tissue is not fully understood. The objective of this study was to assess degenerative changes of cervical spinal segments undergoing discectomy procedures, in vivo.ResultsDiscectomies led to a 60% drop in disc height and 24% drop in foraminal height. Segments did not fuse but showed osteophyte formation as well as endplate sclerosis. MR imaging revealed terminal degenerative changes with collapse of the disc space and loss of T2 signal intensity. The endplates showed degenerative type II Modic changes. Quantitative MR imaging revealed that over 95% of Nucleus Pulposus tissue was extracted and that the nuclear as well as overall disc hydration significantly decreased. Histology confirmed terminal degenerative changes with loss of NP tissue, loss of Annulus Fibrosus organization and loss of cartilage endplate tissue. The bony endplate displayed sclerotic changes.ConclusionDiscectomies lead to terminal degenerative changes. Therefore, these procedures should be indicated with caution specifically when performed for prophylactic purposes.

Current Approaches to the Management of Acute Thoracolumbar Disc Extrusion in Dogs

“…In the context of acute canine IVDE, fenestration is performed “always” or “most of the time” by 69% of board-certified neurologists and 36% of board-certified surgeons ( 26 ). Clinicians who do not routinely fenestrate cite concerns including questionable efficacy; prolonged surgical time; complications such as hemorrhage, pneumothorax or nerve root injury; variable success in removal of in situ nucleus pulposus; potential for introduction of additional disc material into the vertebral canal; induction or worsening of degenerative changes to non-herniated discs, and the concern for adjacent segment disease ( 70 , 71 ). Clinicians who do routinely fenestrate cite a recurrence rate as high as 40% for IVDE and the fact that dogs who present for a second bout of surgical IVDE have a rate of euthanasia as high as 44%, often due to financial concerns of the owner ( 34 , 72 ).…”

Composite biomaterial repair strategy to restore biomechanical function and reduce herniation risk in an ex vivo large animal model of intervertebral disc herniation with varying injury severity

“…Discectomy procedures alleviate many symptoms associated with IVD herniation but do not address the damage and loss of NP and AF tissues which can result in reherniation and recurrent pain [6–10]. This 2 part biomechanical study developed and characterized injectable IVD biomaterial repair strategies capable of being applied during discectomy procedures to repair herniated IVDs.…”

“…Furthermore, the IVD is avascular and has a low cell-density, which contributes to its poor healing potential [4,5]. As such, there is a need to develop improved IVD repair strategies to prevent disc height loss, altered biomechanics, and accelerated degeneration from IVD injury and complications from discectomy procedures, including reherniation and recurrent pain at the same level [6–10].…”

Canine models of spine disorders

“…When considering all of the factors involved in selecting an animal model including availability, ethics, cost, and translational applicability, canine models can also be considered strong candidates. [58][59][60] Spontaneous and induced canine IVDD models have been used to investigate a wide spectrum of biologic, biomechanical, and clinical components of spine disorders in their human counterparts (Table 3). 63 As such, annular injury models can allow for assessments of biochemical, histologic, and biomechanical perturbations that lead to the clinical manifestations of symptomatic IVDD.…”

“…Animal models range from rodents to primates, induced to spontaneous, and acute to chronic with spontaneous disc degeneration in nonhuman primates, age‐related disc degeneration in mice, and genetically‐engineered spontaneous disc degeneration in mice having attractive modeling characteristics. When considering all of the factors involved in selecting an animal model including availability, ethics, cost, and translational applicability, canine models can also be considered strong candidates 58‐60 . Spontaneous and induced canine IVDD models have been used to investigate a wide spectrum of biologic, biomechanical, and clinical components of spine disorders in their human counterparts (Table 3).…”