Adult cervical deformity: radiographic and osteotomy classifications

Adult cervical spine deformity: a state-of-the-art review

Adult cervical deformity is a structural malalignment of the cervical spine that may present with variety of significant symptomatology for patients. There are clear and substantial negative impacts of cervical spine deformity, including the increased burden of pain, limited mobility and functionality, and interference with patients' ability to work and perform everyday tasks. Primary cervical deformities develop as the result of a multitude of different etiologies, changing the normal mechanics and structure of the cervical region. In particular, degeneration of the cervical spine, inflammatory arthritides and neuromuscular changes are significant players in the development of disease. Additionally, cervical deformities, sometimes iatrogenically, may present secondary to malalignment or correction of the thoracic, lumbar or sacropelvic spine. Previously, classification systems were developed to help quantify disease burden and influence management of thoracic and lumbar spine deformities. Following up on these works and based on the relationship between the cervical and distal spine, Ames-ISSG developed a framework for a standardized tool for characterizing and quantifying cervical spine deformities. When surgical intervention is required to correct a cervical deformity, there are advantages and disadvantages to both anterior and posterior approaches. A stepwise approach may minimize the drawbacks of either an anterior or posterior approach alone, and patients should have a surgical plan tailored specifically to their cervical deformity based upon symptomatic and radiographic indications. This state-of-the-art review is based upon a comprehensive overview of literature seeking to highlight the normal cervical spine, etiologies of cervical deformity, current classification systems, and key surgical techniques.

Development of Risk Stratification Predictive Models for Cervical Deformity Surgery

BACKGROUND

As corrective surgery for cervical deformity (CD) increases, so does the rate of complications and reoperations. To minimize suboptimal postoperative outcomes, it is important to develop a tool that allows for proper preoperative risk stratification.

OBJECTIVE

To develop a prognostic utility for identification of risk factors that lead to the development of major complications and unplanned reoperations.

METHODS

CD patients age 18 years or older were stratified into 2 groups based on the postoperative occurrence of a revision and/or major complication. Multivariable logistic regressions identified characteristics that were associated with revision or major complication. Decision tree analysis established cutoffs for predictive variables. Models predicting both outcomes were quantified using area under the curve (AUC) and receiver operating curve characteristics.

RESULTS

A total of 109 patients with CD were included in this study. By 1 year postoperatively, 26 patients experienced a major complication and 17 patients underwent a revision. Predictive modeling incorporating preoperative and surgical factors identified development of a revision to include upper instrumented vertebrae > C5, lowermost instrumented vertebrae > T7, number of unfused lordotic cervical vertebrae > 1, baseline T1 slope > 25.3°, and number of vertebral levels in maximal kyphosis > 12 (AUC: 0.82). For developing a major complication, a model included a current smoking history, osteoporosis, upper instrumented vertebrae inclination angle < 0° or > 40°, anterior diskectomies > 3, and a posterior Smith Peterson osteotomy (AUC: 0.81).

CONCLUSION

Revisions were predicted using a predominance of radiographic parameters while the occurrence of major complications relied on baseline bone health, radiographic, and surgical characteristics.

Risk-benefit assessment of major versus minor osteotomies for flexible and rigid cervical deformity correction

Introduction:

Osteotomies are commonly performed to correct sagittal malalignment in cervical deformity (CD). However, the risks and benefits of performing a major osteotomy for cervical deformity correction have been understudied. The objective of this retrospective cohort study was to investigate the risks and benefits of performing a major osteotomy for CD correction.

Methods:

Patients stratified based on major osteotomy (MAJ) or minor (MIN). Independent t-tests and Chi-squared tests were used to assess differences between MAJ and MIN. A sub-analysis compared patients with flexible versus rigid CL.

Results:

137 CD patients were included (62 years, 65% F). 19.0% CD patients underwent a MAJ osteotomy. After propensity score matching for cSVA, 52 patients were included. About 19.0% CD patients underwent a MAJ osteotomy. MAJ patients had more minor complications (P = 0.045), despite similar surgical outcomes as MIN. At 3M, MAJ and MIN patients had similar NDI, mJOA, and EQ5D scores, however by 1 year, MAJ patients reached MCID for NDI less than MIN patients (P = 0.003). MAJ patients with rigid deformities had higher rates of complications (79% vs. 29%, P = 0.056) and were less likely to show improvement in NDI at 1 year (0.95 vs. 0.54, P = 0.027). Both groups had similar sagittal realignment at 1 year (all P > 0.05).

Conclusions:

Cervical deformity patients who underwent a major osteotomy had similar clinical outcomes at 3-months but worse outcomes at 1-year as compared to minor osteotomies, likely due to differences in baseline deformity. Patients with rigid deformities who underwent a major osteotomy had higher complication rates and worse clinical improvement despite similar realignment at 1 year.

A new nomenclature system for the surgical treatment of cervical spine deformity, developing, and validation of SOF system

PURPOSE

To develop and assess the reliability of new nomenclature system that systematically organizes osteotomy techniques and briefly describes the surgical approach, the surgical sequence, and the fixation technique for cervical spine deformity (CSD).

METHODS

We developed a new classification system (SOF system) for CSD surgery that describes the sequence of surgical approach (S), the grade of osteotomy (O), and the information of fixation (F) using alphanumeric codes. Twenty CSD osteotomies (8 anterior osteotomies, 12 posterior osteotomies) were included in this study to evaluate the inter- and intra-observer agreement based on operation records. Six observers performed independent evaluations of the operation records in random order. Each observer described 20 CSD surgeries using the SOF system twice (> 30 days between assessments) based on operation records to validate SOF system.

RESULTS

Overall agreement (among all six observers at the initial assessment) on the anterior and posterior osteotomy was ICC = 0.96 and ICC = 0.91, respectively. Overall agreement (repeat observations after at least 30 days) on the anterior and posterior osteotomy was ICC = 0.96 and ICC = 0.91, respectively. This data showed that both inter- and intra-observer agreement revealed 'excellent'.

CONCLUSION

This study introduces the SOF system of the CSD surgery to understand the surgical sequence, the type of osteotomy and the fixation techniques. The investigation of the inter- and intra-observer agreement revealed 'excellent agreement' for both anterior and posterior osteotomies. Thus, SOF system can provide a consistent description of the various CSD surgeries and its use will provide a common frame for CSD surgery and help communicate between surgeons.

Severe, rigid cervical kyphotic deformity associated with SAPHO syndrome successfully treated with three-stage correction surgery combined with C7 vertebral column resection: a technical case report

STUDY DESIGN

Case report.

OBJECTIVES

To describe the first reported use of corrective surgery combined with C7 vertebral column resection (VCR) to treat an extremely rare case of severe, rigid cervical kyphotic deformity associated with synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome.

BACKGROUND DATA

Spinal lesions reportedly occur in 32-45% in SAPHO syndrome. However, bone and joint lesions are usually repaired such that severe joint destruction is rare. Therefore, there have been few reported cases of surgical treatment for spinal lesions.

METHODS

A 22-year-old woman had been diagnosed with cervical kyphotic deformity associated with SAPHO syndrome. She had difficulty looking upward. On radiography, the C4-C7 vertebral bodies were fused and exhibited severe rigid kyphotic deformity. Right convex scoliosis with a Cobb angle of 22° was apparent at C5-T2, and the C2-C7 angle of kyphosis was 75°. Corrective three-stage surgery was carried out from the anterior, posterior, and anterior, with C7 VCR.

RESULTS

The C2-T1 angle improved to 21° and the patient was capable of looking up. At present, 2 years postoperatively, complete bony fusion has been achieved. Her cervical spine function and quality of life were markedly improved.

CONCLUSION

Only a very limited number of patients have a deformity sufficiently severe that VCR of cervical vertebra is required, but as this is the technique that provides the greatest multiplanar alignment correction, its choice in the present case was appropriate.

LEVEL OF EVIDENCE

IV.

SOF System; A New Nomenclature System for the Surgical Techniques of Cervical Spine Deformity

Although cervical spinal deformity (CSD) can have a profoundly negative impact on an individual’s quality of life and there have been many advances in surgical treatment of CSD in recent years, there exists no comprehensive classification system of surgical treatment that categorizes anterior and posterior surgery separately according to the grade of surgery. The objective of this study is to introduce the new classification system of various surgical treatments for CSD. We developed a new classification system (SOF system) for CSD surgery that describes the sequence of surgical approach (S), the grade of osteotomy (O), and the information of fixation (F) using alphanumeric codes. This new classification system can provide a consistent description of the various osteotomies performed in CSD surgery. Especially, regarding research, there has been a clear benefit to this classification. Having a standardized classification that allows for common frame for cervical deformity correction surgery, communication between surgeons and the evaluation of the CSD surgeries make it possible to conduct global comparative research about surgical outcome.

Restoration of Global Sagittal Alignment After Surgical Correction of Cervical Hyperlordosis in a Patient with Emery-Dreifuss Muscular Dystrophy: A Case Report

CASE

We report a rare cervical hyperlordotic deformity in a 19-year-old woman with Emery-Dreifuss muscular dystrophy and concomitant scoliosis. After standard posterolateral instrumentation and fusion of C2-T1 and extensive soft-tissue release, her neck pain improved and unassisted maintenance of cervical alignment and horizontal gaze were preserved through an 8-year follow-up. More importantly, she exhibited reciprocal correction of compensatory global sagittal malalignment, including lumbar lordosis.

CONCLUSIONS

This case highlights the importance of full-spine analysis for all patients with spinal deformity to identify and differentiate primary driver(s) of deformity from compensatory mechanisms to individualize treatment toward what truly drives the patient's disability.