Cantilever method for severe kyphotic deformity correction in spondylitis tuberculosis: A technical note and literature review

Improved Kyphotic Restoration Reduces the Incidence of Adjacent Vertebral Fracture in Patients With Osteoporotic Vertebral Compression Fractures Treated by Percutaneous Kyphoplasty: A Clinical Study and Corresponding Numerical Simulations

OBJECTIVE

Adjacent vertebral fracture (AVF) is a commonly observed complication in patients with osteoporotic vertebral compressive fractures (OVCF) following percutaneous kyphoplasty (PKP). The primary etiology of this complication is the deterioration of the biomechanical environment. Local kyphotic deformity plays a critical role in influencing the direction of load transmission, which subsequently affects the local biomechanical conditions. However, whether the improved restoration of sagittal alignment can biomechanically lower the incidence of AVF remains to be determined. This paper aimed to investigate the influence of kyphotic deformity on AVF and its corresponding biomechanical mechanism.

METHODS

Clinical data of PKP-treated patients with OVCF were retrospectively reviewed in this study. The current patient cohort was divided into two groups based on the clinical outcomes observed during the follow-up period (with and without AVF). Kyphotic angles were measured from the preoperative and postoperative lateral radiographs of these patients, and the variations between these values were calculated to denote the kyphotic restoration value. Significant differences in these parameters were analyzed between patients with and without AVF. Moreover, the biomechanical influences of segmental kyphotic angles on adjacent segment stress values were determined using a well-validated numerical model to explain the biomechanical mechanisms underlying clinically observed phenomena.

RESULTS

Clinical data of 121 PKP-treated patients with OVCF were enrolled in this study. The preoperative kyphotic angles between the two groups were comparable (12.83 ± 5.98, 12.93 ± 6.66, p = 0.942). By contrast, compared with patients with AVF, patients without AVF suffered significantly lower postoperative kyphotic angle values (10.11 ± 4.84, 7.85 ± 5.24, p = 0.044). Correspondingly, the kyphotic restoration was significantly better in patients without AVF (2.72 ± 2.26, 5.08 ± 4.2, p = 0.055). In addition, stress concentration is more evident in the model with severe fracture segmental kyphosis.

CONCLUSIONS

The clinical review and biomechanical simulations revealed that a greater degree of kyphotic correction during PKP procedures, along with a decreased postoperative kyphotic deformity, may help lower the incidence of AVF by easing stress concentration in the neighboring vertebral bodies. This topic deserves further validation through future prospective studies.

Techniques of Deformity Correction in Adolescent Idiopathic Scoliosis-A Narrative Review of the Existing Literature

Surgical management of adolescent idiopathic scoliosis [AIS] is a complex undertaking with the primary goals to correct the deformity, maintain sagittal balance, preserve pulmonary function, maximize postoperative function, and improve or at least not harm the function of the lumbar spine. The evolution of surgical techniques for AIS has been remarkable, transitioning from rudimentary methods of spinal correction to highly refined, biomechanically sound procedures. Modern techniques incorporate advanced three-dimensional correction strategies, often leveraging pedicle screw constructs, which provide superior rotational control of the vertebral column. A number of surgical techniques have been described in the literature, each having its own pros and cons. This narrative review provides a detailed analysis of the contemporary surgical techniques used in the treatment of patients with AIS.

Comparison of Overall Complication Rates in VCR-Based vs Non-VCR-Based Corrective Techniques in Severe Rigid Kyphoscoliosis Patients: A Systematic Review and Meta-Analysis

STUDY DESIGN

Systematic review and meta-analysis.

OBJECTIVE

Compilation of complication outcomes data from the surgical management of severe rigid kyphoscoliosis patients using VCR-based vs non-VCR-based corrective maneuvers is lacking. This meta-analysis aimed to compare complication outcomes between those classified osteotomy approaches.

METHODS

Thorough literature review and meta-analysis were conducted between January 2000 and September 2021. The selection criteria were studies: i) reporting major curve Cobb angle of ≥80° and flexibility of <25% or 30%; ii) comparing VCR or ≥ Type V Schwab osteotomy defined as VCR-based vs [non-VCR-based] techniques, (any osteotomy or technique other than VCR); iii) published in English with ≥10 patients; iv) reporting complication rates; and v) having minimum of 2-year follow-up. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated. Significance level was set at (P < .05).

RESULTS

Of the 174 patients included, 52.30% (n = 91) and 47.70% (n = 83) were VCR-based and non-VCR-based, respectively. The incidence of dural tears/nerve injuries/significant intraoperative-neuromonitoring changes was significantly higher; [OR = 6.78, CI= (1.75 to 26.17), I2 = 0%, (P = .006)] in the VCR-based group than the non-VCR-based group. The 'overall surgical and medical' complication rate was significantly higher in the VCR-based group, [OR = 1.94, CI= (1.02 to 3.67), I2 = 31%, (P = .04)].

CONCLUSION

Both VCR-based and non-VCR-based surgical techniques for management of severe rigid scoliosis and kyphoscoliosis patients pose comparable overall surgical complication rates, while a significantly higher perioperative neurological complication incidence was associated with VCR-based technique compared to the non-VCR-based techniques. The VCR-based technique was associated with 6.78 times higher incidence of neurological complications compared to non-VCR-based techniques.

Single-Stage Posterior Approach for a Neglected Severe Kyphotic Spine With a Three-Year Follow-Up

Neglected spinal tuberculosis with severe kyphosis is uncommon. Spinal tuberculosis can present with back pain, neurological deficits, cold abscesses, or severe deformities. Diagnosis is made using laboratory, imaging, and tissue studies. Management can be done medically or surgically. As neurological deficits or severe deformities worsen, most surgeons prefer a surgical option. There have been different opinions regarding the surgical approach for spinal tuberculosis. This is a case of neglected spinal tuberculosis with severe kyphotic deformity treated with single-stage posterior instrumentation and fusion without any complications within in a three-year follow-up period.

Freehand Pedicle Screw Insertion in Spondylitis Tuberculosis Kyphosis Correction Using Cantilever Method: A Breach Rate Analysis of 168 Consecutive Screws

Background

The cantilever method is a standard for two-dimensional deformity correction, as in spondylitis tuberculosis kyphotic deformity. An accurate and secured pedicle screw placement as part of the correction tools is essential to accommodate reduction while preventing screw-related complications. Many literatures have described the pedicle screw misplacement in cases with “normal” bone quality (ie, scoliosis, Scheuermann’s kyphosis, ankylosing spondylitis, trauma) or in the obviously abnormal bone such as osteoporosis. However, to our knowledge, the pedicle screw accuracy in cases of deformity correction of tuberculous kyphosis was not previously reported.

Methods

This is a retrospective study of 168 pedicle screws in 14 consecutive cases of spondylitis tuberculosis with kyphotic deformity. The cantilever reduction method with freehand screw insertion technique was done in all cases to correct the deformity. Postoperative computed tomography (CT) evaluation was done to evaluate screw position and breach rates.

Results

Among the 168 screws, accurate pedicle screw placement was accomplished in 39.3% screws (Gertzbein–Robbins Grade A). The overall breach rate was 61.9%, which was most commonly occurred on the segment proximal to the apex of the deformity (p=0.001). The lateral breach was more common than the medial breach (52.3% vs 7.7%). The pedicle screw on the thoracal region has a greater breach incidence than those on the lumbar region especially those on T9, T10, and T11. There was no injury to the surrounding neurovascular and pleural structures. No revision surgeries were required.

Conclusion

Freehand pedicle screw insertion in spondylitis tuberculosis kyphotic reduction has proved to be safe. However, the accuracy should be improved to prevent long-term screw-related complications.

Effectiveness of Kyphosis Reduction Using Cantilever Method in Thoracolumbar Spondylitis Tuberculosis: A Short-Term Follow-Up

Background

Kyphosis in spondylitis tuberculosis (STb) is more than just a cosmetic issue. It has a potentially detrimental effect on both spine-associated structures and cardiopulmonary function. It can be corrected in any stage of STb; however, the corrective surgery is challenging, especially in the late case, in which the additional stiffness of the spine can come into consideration. To date, the cantilever technique is still a gold standard for sagittal plane deformity correction. However, no study to date has explored its effectiveness for thoracolumbar kyphotic deformity, especially that caused by spondylitis tuberculosis.

Methods

This is a retrospective study of 16 consecutive cases of spondylitis tuberculosis with thoracolumbar kyphosis that underwent corrective surgery in our center in the period of 2020–2021. We aim to evaluate the effectiveness of the cantilever technique that we use for kyphotic correction in thoracolumbar STb patients.

Results

At the 3-months follow-up, the mean Cobb angle was 14.6°±10.27°, with the mean gain of 20.90°±12.00° and positively correlate with the thoracolumbar kyphosis (TLK) correction (68.69%, r = 0.654, p = 0.001). The mean thoracic kyphosis, lumbar lordosis, and sagittal vertebral axis were 30.6°±13.08°, 39.4°±16.02°, and 1.4±4.09 cm, respectively, with sagittal Cobb difference of 12.70±9.85.

Conclusion

The kyphotic Cobb angle reduction by cantilever technique in the thoracolumbar area significantly improved the thoracolumbar kyphosis and realign the spinal sagittal axis. Thus, the cantilever technique remains the gold standard for sagittal plane deformity correction which can be applied for kyphotic deformity correction in thoracolumbar STb cases.