Posterior thoracic discectomy and interbody fusion for the correction of severe hyperkyphotic deformity: technical note and case report

Introduction

Cervical spine degeneration secondary to rheumatoid arthritis (RA) has the potential to cause cranial settling, atlanto-axial instability and subaxial cervical spine subluxation with resultant neurological deficit secondary to cord compression (1,2). This chronic systemic inflammatory disease affects both the bony joints as well as ligaments with the underlying pathophysiology believed to involve the activation of CD4⁺ T cells, B lymphocytes and autoantibodies which promote leucocyte influx and cartilage breakdown (3). Contemporary disease modifying anti-rheumatic drugs (DMARDs) and biologic agents have led to a drastic reduction in cervical spine manifestations (4). However, these patients are also often osteoporotic due to the use of steroids for arthritic flares (4).

We present the unique case of a patient with cervical myelopathy as a consequence of multi-level cervical cord compression from spondylolisthesis and cervical spine subluxation which was managed with posterior decompression and C2–T2 posterior fusion. Despite an excellent immediate postoperative outcome, there was catastrophic mechanical failure of her bone six months later with a significantly angulated T1/2 kyphotic deformity which was operatively managed by the use of a sole posterior approach with circumferential fusion and successful placement of an anterior cervical discectomy cage by a modified transpedicular and partial trans-facet route. This is the first report to our knowledge of such significant deformity correction using this posterior approach alone with adequate column support. We present this article in accordance with the CARE reporting checklist (available at https://jss.amegroups.com/article/view/10.21037/jss-2025-aw-203/rc).

Case presentation

A 75-year-old presented with 3 months of progressive gait disturbance and fine motor dysfunction in the hands. She described axial neck pain and left sided radicular pain radiating to the fingers. This lady denied any sphincter disturbance. On examination she exhibited an unsteady gait with brisk lower limb reflexes and upgoing plantars. This was consistent with Ranawat class 3A myelopathy. Importantly, she had a past medical history significant for RA on methotrexate and etanercept injections as well as long term prednisolone 5 mg daily. Additionally, she suffered from chronic obstructive pulmonary disease secondary to a 10-pack-year smoking history, hypothyroidism, osteoarthritis, hypertension, depression and reflux. Prior to presentation she had been ambulating independently and living at home. Her biochemical markers revealed a slightly elevated C-reacted protein of 18 mg/L and a serum albumin of 33 g/L suggesting unremarkable nutritional status.

Computed tomography (CT) and magnetic resonance imaging (MRI) confirmed subaxial degenerative spondylolisthesis at C3/4 with canal stenosis but no signal change in the canal. Similar findings were demonstrated at C7/T1 with cord compression and signal change. Above this, C6/7 also displayed canal stenosis without overt cord compression whilst T1/2 displayed a subtle degenerative spondylolisthesis without canal stenosis. Furthermore, there was fusion noted from the spinous processes of C2 to C4 (Figure 1). There was auto-fusion between the C4–7 segments as well as unilaterally between the C2/3 facets. Given the symptomatic disabling cervical myelopathy, a posterior C6–T1 laminectomy and C2–T2 instrumented fusion was performed utilizing a right C2 pedicle screw and left C2 lamina screw. Post-operative CT and MRI confirmed satisfactory hardware position and alignment with excellent cord decompression (Figure 2). She recovered well and began walking immediately and completed two weeks of rehabilitation before being discharged home.

Figure 1 Preoperative T2-weight MRI in the sagittal (A) and axial planes through C3 (B) and C7 (C) demonstrating subaxial subluxation as a manifestation of rheumatoid arthritis resulting in C2/3 and C7/T1 spondylolisthesis with cord compression and early signal change. A left C7/T1 facet cyst is also noted contributing to cord compression (C). Preoperative CT in the sagittal (D) and axial planes through C7 (E) demonstrated auto-fusion of intermediate segments from C4–C6. CT, computed tomography; MRI, magnetic resonance imaging.

Figure 2 Postoperative T2-weight MRI demonstrates excellent cervical cord compression (A) with satisfactory hardware positioning on the right (B) and left (C) parasagittal planes with C2–T2 fixation. CT, computed tomography; MRI, magnetic resonance imaging.

The patient re-presented 6 months later with a one-week history of inability to walk which had been precipitated by a coughing fit in the setting of pneumonia during which she heard an audible crack in her spine. Repeat cervical spine imaging demonstrated a severe T1/2 kyphosis with fracture of bilateral T2 pedicles at the caudal end of the construct and cord compression despite the existing laminectomy (Figure 3). Given her osteoporotic bone, the T2 pedicles had fractured in flexion/distraction pattern similar to a bony chance fracture with the hardware remaining intact. There were no signs on MRI there was infection or underlying neoplastic disease. We hypothesize that the coughing fit resulted in a transient moment of forced kyphosis precipitating the final failure of her hardware. She proceeded to undergo a revision surgery with the surgical goals being reduction of her kyphotic deformity, thoracic cord decompression and extension of her fusion caudally to achieve fixation and stability.

Figure 3 Delayed postoperative T2-weighted MRI in the sagittal plane (A) demonstrates significant T1/2 kyphotic deformity with severe angulation and resultant cord compression despite an adequate laminectomy. CT sagittal planes in the midline (B) as well as right paramedian (C) and left paramedian (D) confirm failure of the T2 pedicles resulting in a bony chance fracture bilaterally rather than hardware failure. MRI, magnetic resonance imaging.

After fibreoptic intubation under a general anaesthetic, a rotisserie turn was performed facilitate prone positioning on a Trios table in the cervical management system with neuromonitoring. A strict mean arterial blood pressure of above 80 mmHg was maintained at all times. Baseline intraoperative cervical X-rays were obtained to check on-table alignment and also confirm the intraoperative target level (Figure 4). The deformity was clearly visualised. Standard monopolar periosteal dissection was performed to expose the entire previous posterior fixation from C2–T2 with caudal extension to expose six levels below the inferior end of the failure in preparation for further distal fusion. Previous set screws and rods from the existing C2–T2 construct were removed before a test of mobility of performed. No significant reduction was possible at this stage given the intact anterior longitudinal ligament (ALL) and disc, and traditional approaches would be limited by the chin on chest deformity.

Figure 4 Intraoperative fixation and radiographs. Intraoperative photograph demonstrating skeletonized thoracic spinal cord with exiting T2 nerve roots bilaterally (A). The left pedicle was drilled flush whilst the right pedicle was relatively preserved. Despite this, adequate ventral access to place an anterior cervical discectomy and fusion titanium cage was gained without further disruption of the posterior elements (A). Intraoperative fluoroscopy in the sagittal planes demonstrating correction prior to traction and manipulation (B) and kyphotic correction after the posterior thoracic discectomy and fusion (C).

At this T1/2 level, an anterior approach would prove impractical even with splitting of the sternum given the acute angle of surgery required. As such, with the intention of achieving mobility and access to the anterior column, the left pedicle and facet were drilled until the disc space was reached with a window established beneath the T2 nerve roots bilaterally. The disc space was prepared by clearing the cartilaginous endplates with curettes and critically it was possible to release the ALL from a pure posterior approach with curettes and Kerrison’s rongeurs. An appropriately sized 5-mm titanium cage (4Web, small footprint, 7 degrees lordosis) was inserted into the T1/2 disc space although this hardware was originally designed for use in an anterior cervical discectomy and fusion rather than a posterior thoracic discectomy approach. Distraction was then performed after loosening the Mayfield attachment carefully achieving good reduction before the head was again secured in place.

In order to support this anterior column, a further six levels of bilateral posterior pedicle screw fixation were performed bilaterally under fluoroscopic guidance before the entire construct was connected with transitional rods. The transition point of the rod was selected to be C7/T1 specifically at a higher level to the original deformity bony failure point of T1/2 to minimize the chance of hardware failure. Generous bone graft was placed across the entire construct. Neuromonitoring demonstrated improved somatosensory and motor evoked potentials at the end of the operation. Postoperative CT confirmed excellent realignment of her cervicothoracic spine with an MRI confirming cord decompression (Figure 5). Clinically she began standing on the first postoperative day and walked with assistance the following day. Following consultations with rheumatology and endocrinology, a plan was implemented for weaning of her steroids and her bone health was optimized with vitamin D supplementation and aggressive management with anti-resorptive therapy. In keeping with the latest guidelines, methotrexate and etanercept may be continued but if there are wound healing concerns perioperatively then one cycle is withheld (5), This was in keeping with our management. Retained correction of kyphosis with satisfactory alignment and stable hardware positioning was confirmed on follow-up six months postoperatively (Figure 6).

Figure 5 Immediate postoperative CT in the sagittal median (A), right parasagittal (B), left parasagittal (C) and coronal (D) planes demonstrating T1/2 kyphotic correction with restoration more anatomical alignment and resultant thoracic cord compression. Extension of the fusion has been performed to provide sturdy posterior fixation 6 levels below the previous failure point which is supported by the anterior cervical fusion titanium cage which was placed by a lone posterior approach. Postoperative MRI in the sagittal plane (E) is degraded by hardware artefact but demonstrates satisfactory cord compression. CT axial plane (F) at the level of the cage demonstrates the bony removal with a left transpedicular approach but relative preservation of the right pedicle. CT, computed tomography; MRI, magnetic resonance imaging.

Figure 6 Postoperative CT at six months of the left parasagittal cervical region (A), right parasagittal cervical region (B), left parasagittal thoracic region (C) and right parasagittal thoracic region (D) planes demonstrating retention of the correction of the hyperkyphotic alignment with good bony fusion of the posterior elements. (E) Mid-sagittal demonstrating satisfactory and unchanged cage position. CT, computed tomography.

Ethical consideration

All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Declaration of Helsinki and its subsequent amendments. Written informed consent was obtained from the patient for publication of this case report and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

Discussion

This is a novel case of a patient with symptomatic myelopathy in the setting of longstanding RA of the cervical spine despite treatment with methotrexate and the biologic agent etanercept. This lady suffered mainly from subaxial subluxation with regions of resultant auto-fusion without the other classical manifestations such as basilar invagination or atlanto-axial subluxation. Her first cervicothoracic decompression and fixation was uncomplicated and she recovered her mobility. Unfortunately, her osteoporotic bone, on the background of longstanding steroid use, resulted in eventual T1/2 distal junctional bony failure requiring revision surgery to correct her deformity and extend her fusion caudally (6). Risk factors for this distal junctional kyphosis failure include multi-level construct, poor bone quality and also the loss of usual cervical lordosis (7). This is especially important given acceptable global spinal sagittal alignment has been demonstrated to be protective against future deformity (8). The acute angulation of her deformity precluded an anterior approach, and therefore a posterior approach alone was required. A modified left transpedicular and partial trans-facet approach to place a cervical cage for anterior column support was employed without any nerve root sacrifice which is an innovative technique and to our knowledge the first description of such a novel surgical method.

Traditional approaches to the thoracic spine to perform a discectomy or corpectomy can be categorized into an anterior only approach, posterior only approach or a combined approach. A direct anterior approach in our unique case would involve splitting of the sternum given the deformity level of T1/2 being too low for a traditional Smith-Robinson approach. The final options constituted open posterior thoracic approaches to perform corpectomy including a transpedicular costotransversectomy or lateral extra-cavitary corpectomy (9,10). These are quite destructive approaches involving extensive posterior thoracic extensor muscle dissection, fascia splitting and lateral exposure followed by resection of a rib head and pedicle to achieve a discectomy and corpectomy without excessive spinal thoracic spinal cord manipulation (11). Concerns regarding this approach, especially in elderly patients, centre on degree of blood loss and length of time in a prone position with significant postoperative pain (11,12).

As such, Bransford et al. pioneered the use of the modified transfacet pedicle-sparing decompression and fusion (13). This approach permits expansion of the surgical field after standard laminectomy by removing a portion of the facet complex without violating the facet (14). Alimohammadi et al. utilized this approach in 163 consecutive patients with unstable thoracolumbar burst fractures with canal compromise who underwent trans-facet pedicle-sparing procedure (14). These authors found statistically significant improvement in both neurological outcomes as measured by Frankel grade (P<0.05) and Oswestry Disability Index (P<0.01) (14).

Given our circumstances which prohibited any meaningful anterior approach, a solely posterior approach was selected. This was despite the fact that posterior approaches are usually typically reserved for lateral discs rather than purely anterior disc fragments which are more suited to the anterolateral approaches (15). Placement of a thoracic interbody cage is also anterior enough to rest on the apophyseal ring to sustain load bearing forces. Importantly, Shedid et al. noted surgeons are more comfortable and familiar performing the posterior approach (16). Epstein et al. emphasized the importance recognizing that laminectomy alone is insufficient in the treatment of thoracic cord compression (17). Patterson and Arbit therefore introduced the technique of posterolateral transpedicular discectomy without laminectomy (18). Bilsky et al. investigated the utility this transpedicular approach for thoracic disc herniations and achieved this by drilling the pedicle but leaving the lateral and inferior cortices intact in combination with partial superior and inferior facetectomies to achieve disc resection from a posterior approach (12). Cristaldi et al. highlighted the versatility of this approach for resection of ventrally located spinal cord lesions (19). This has ultimately been modified into a trans-facet pedicle-sparing approach by Stillerman et al. who argued that pedicle preservation was essential and accessing the disc space by drilling the facet instead was preferable. Bransford et al. interrogated this transfacet pedicle sparing technique in a series of 34 patients and determined superior outcomes with respect to pain scores as measured by the visual analogue scale and shorter length of stay (4.2 versus 7.3 days, P<0.03) compared to an anterior surgical approach (20).

When evaluating which approach is superior between the trans-pedicular or trans-facet, Patel et al. found both techniques equally useful for the treatment of disc herniations (21). Nonetheless, more extensive exposures where a corpectomy is required such as for malignant vertebral tumour resection, Lau et al. described a mini-open transpedicular approach for corpectomy and achieved good functional outcomes (11). In this surgical technique, the fascia is preserved rather than the extensive soft tissue dissection of open transpedicular approaches with the authors contending this results in superior functional outcomes (11). The primary outcome of length of hospital stay was 7 days compared to the usual 10–12 days reported in the literature (11). However, these cases of metastatic tumour removal where spinal alignment is still relatively preserved are not as challenging as our severely hyperkyphotic deformity case with cord compression. Importantly, Shi et al. noted that nerve root sacrifice is often required for the placement of a cage (22).

Our case demonstrated it is technically feasible to access the disc space by performing modified transpedicular and trans-facet approaches on each side. The left pedicle was drilled as well as the medial facet more than right pedicle, with Kerrison punches demonstrating access to the disc space to complete the discectomy (Figure 4). Intraoperative adjustment of the Mayfield frame holding the head facilitated intraoperative reduction and correction of the kyphotic deformity as confirmed on intraoperative fluoroscopy. We recognized that uncovering of the disc at the index level also contributed to cord contribution but managed to achieve a complete discectomy as well as release of the ALL from a sole posterior approach (Figure 5).

Despite our successful clinical and radiological outcome using this posterior thoracic discectomy and fusion, more similar to the original posterior lumbar interbody fusion technique first proposed by Cloward, the ideal management of thoracic kyphotic correction remains controversial and likely highly individual patient dependent (23). In many ways, the kyphotic correction we achieved also relied upon partial posterior pedicle subtraction osteotomies to attempt to reduce kyphosis which, when combined with posterolateral fusion, allowed reduction of the T1/2 angulation (24). This is not always possible in cases where significant instability has already been demonstrated with failure and resultant fracture of osteoporotic bone, as in our case, without extension of the hardware to allow leverage of the entire construct. Sciubba et al. described their series of patients of surgical correction of a surgical kyphotic deformity utilizing circumferential fixation with a lone posterior approach (25). However, the striking feature with their series was that the majority of patients demonstrated single level kyphosis due to a fracture rather than an entire lever of fused osteoporotic bone above the segment (25). It was also necessary in their series to sacrifice the ipsilateral and sometimes the contralateral nerve roots at the lower thoracic nerve root levels (25). Our posterior thoracic discectomy and fusion approach did not require any nerve root sacrifice.

The advantages of this novel surgical technique are the ability to transgress the pedicle and facet to access the disc space without spinal cord manipulation. More than this, we have demonstrated that release of the anterior ligamentous structures is possible from a sole posterior approach prior to placement of an anterior cage to assist with load sharing. This was all possible without neural structure sacrifice which improve neuromonitoring as a consequence of the decompression and posterior fixation.

Conclusions

This is the first report of a posterior thoracic discectomy and fusion performed without nerve root sacrifice and we posit this as a viable surgical technique. Various transpedicular and trans-facet approaches have been employed but only to perform discectomies and never to place an interbody device in order to facilitate correction a hyperkyphotic thoracic deformity in a patient with severe osteoporosis and RA.

Acknowledgments

None.

Footnote

Reporting Checklist: The authors have completed the CARE reporting checklist. Available at https://jss.amegroups.com/article/view/10.21037/jss-2025-aw-203/rc

Peer Review File: Available at https://jss.amegroups.com/article/view/10.21037/jss-2025-aw-203/prf

Funding: None.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://jss.amegroups.com/article/view/10.21037/jss-2025-aw-203/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Declaration of Helsinki and its subsequent amendments. Written informed consent was obtained from the patient for publication of this case report and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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