Defining role of atlantoaxial and subaxial spinal instability in the pathogenesis of cervical spinal degeneration: Experience with "only-fixation" without any decompression as treatment in 374 cases over 10 years

Abstract

Aim: The authors analyze their published work and update their experience with 374 cases of cervical radiculopathy and/or myelopathy related to spinal degeneration that includes ossification of the posterior longitudinal ligament (OPLL). The role of atlantoaxial and subaxial spinal instability as the nodal point of pathogenesis and focused target of surgical treatment is analyzed.

Materials and methods: During the period from June 2012 to November 2022, 374 patients presented with acute or chronic symptoms related to radiculopathy and/or myelopathy that were attributed to degenerative cervical spondylotic changes or due to OPLL. There were 339 males and 35 females, and their ages ranged from 39 to 77 years (average 62 years). All patients were treated for subaxial spinal stabilization by Camille's transarticular technique with the aim of arthrodesis of the treated segments. Atlantoaxial stabilization was done in 128 cases by adopting direct atlantoaxial fixation in 55 cases or a modified technique of indirect atlantoaxial fixation in 73 patients. Decompression by laminectomy, laminoplasty, corpectomy, discoidectomy, osteophyte resection, or manipulation of OPLL was not done in any case. Standard monitoring parameters, video recordings, and patient self-assessment scores formed the basis of clinical evaluation.

Results: During the follow-up period that ranged from 3 to 125 months (average: 59 months), all patients had clinical improvement. Of 130 patients who had clinical evidences of severe myelopathy and were either wheelchair or bed bound, 116 patients walked aided (23 patients), or unaided (93 patients) at the last follow-up. One patient in the series was operated on 24 months after the first surgery by anterior cervical route for "adjacent segment" disc herniation. No other patient in the entire series needed any kind of repeat or additional surgery for persistent, recurrent, increased, or additional related symptoms. None of the screws at any level backed out or broke. There were no implant-related infections. Spontaneous regression of the size of osteophytes was observed in 259 patients where a postoperative imaging was possible after at least 12 months of surgery.

Conclusions: Our successful experience with only spinal fixation without any kind of "decompression" identifies the defining role of "instability" in the pathogenesis of spinal degeneration and its related symptoms. OPLL appears to be a secondary manifestation of chronic or longstanding spinal instability.

Keywords: Intervertebral disc; myelopathy; ossification of posterior longitudinal ligament; spondylosis.

Figure 1

Images of a 71-year-old male patient. (a) T2-weighted magnetic resonance imaging (MRI) showing multisegmental spinal degeneration. Buckling posterior longitudinal ligaments and ligamentum flavum are seen, more prominently at C3–4, 4–5, and 5–6 levels, (b) sagittal image of computed tomography (CT) scan showing multiple segment disc space reduction and osteophytes, (c) sagittal image with the cut passing through facets. Abnormalities in facetal alignment, irregular articular surfaces, and osteophytes formation around the articulations can be seen, (d) three-dimensional reconstruction of CT scan showing listhesis of the facets that signal vertical spinal instability, (e) MRI after 9 months of surgery showing reduction of compression by posterior longitudinal ligament and by ligamentum flavum, (f) CT scan reconstruction showing C2–3, C3–4, C4–5, and C5–6 transarticular screw fixation. There is no bone decompression

Figure 2

Images of a 46-year-old male patient. (a) Sagittal T2-weighted magnetic resonance imaging (MRI) cervical spine showing degenerative spinal changes in the form of large osteophytes, more prominently at C5–6 and C6–7 levels, (b) axial image of MRI showing large unilateral osteophyte/disc herniation, (c) postoperative MRI after 12 months of surgery showing a reduction in the size of osteophyte/disc herniation. (d) Postoperative axial MRI showing reduction in the size of osteophyte/disc herniation, (e) postoperative sagittal computed tomography (CT) scan showing no midline bone resection in the form of laminectomy, (f) postoperative CT scan cut through the facets showing transarticular screws, (g) CT scan cut showing arthrodesis of the treated segments

Figure 3

Images of a 56-year-old male patient. (a) Sagittal image of T2-weighted magnetic resonance imaging (MRI) showing evidences of spinal degeneration in the form of osteophytes at multiple segments and evidence of cord compression, (b) sagittal image of computed tomography (CT) scan showing osteophytes, ossification of posterior longitudinal ligament, and disc space reduction at multiple levels. Degeneration of spinal segments extends beyond the levels of compression seen on MRI, (c) CT scan cut passing through the facets showing irregularity of facetal articulation, osteophyte formation along the edges of facets, evidences of bone fusion and reduction in articular spaces, (d) postoperative MRI after 6 months of surgery. Reduction in compression of the spinal cord can be observed, (e) postoperative CT scan showing no midline bone decompression. Reduction in the size of osteophytes and thickness of ossification of the posterior longitudinal ligament can be observed, (f) Postoperative CT scan showing transarticular screw fixation and arthrodesis of the spinal segments