Predictors for cervical kyphotic deformity following laminoplasty: a systematic review and meta-analysis

Abstract

OBJECTIVE Laminoplasty is a common treatment for cervical spondylotic myelopathy (CSM) and for ossification of the posterior longitudinal ligament (OPLL). However, approximately 21% of patients undergoing laminoplasty develop cervical kyphotic deformity (KD). Because of the high prevalence rate of KD, several studies have sought to identify predictors for this complication, but the findings remain highly inconsistent. Therefore, the authors performed a systematic review and meta-analysis to establish reliable preoperative predictors of KD. METHODS PubMed, Scopus, and Web of Science databases were used to systematically extract potential references. The first phase of screening required the studies to be written in the English language, involve patients treated for CSM and/or OPLL via laminoplasty, and report postoperative cervical KD. The second phase required the studies to provide more than 10 patients and include a control group. The mean difference (MD) and odds ratio (OR) were calculated for continuous and dichotomous parameters. Study quality was evaluated using the Newcastle-Ottawa Scale. CSM and OPLL patients were further assessed by performing subgroup analyses. RESULTS Thirteen studies comprising patients who developed cervical KD (n = 296) and no KD (n = 1254) after receiving cervical laminoplasty for CSM or OPLL were included in the meta-analysis. All studies were retrospective cohorts and were rated as high quality. In the combined univariate analysis of CSM and OPLL patients undergoing laminoplasty, statistically significant predictors for postoperative KD included age (MD 2.22, 95% CI 0.16–4.27, p = 0.03), preoperative BMI (MD 0.85, 95% CI 0.06–1.63, p = 0.04), preoperative C2–7 range of flexion (MD 10.42, 95% Cl 4.24–16.59, p = 0.0009), preoperative C2–7 range of extension (MD −4.59, 95% CI −6.34 to −2.83, p < 0.00001), and preoperative center of gravity of the head to the C7 sagittal vertical axis (MD 26.83, 95% CI 9.13–44.52, p = 0.003). Additionally, among CSM patients, males were identified as having a greater risk for postoperative KD (OR 1.73, 95% CI 1.02–2.93, p = 0.04). CONCLUSIONS The findings from this study currently provide the largest and most reliable review on preoperative predictors for cervical KD after laminoplasty. Given that several of the included studies identified optimal cutoff points for the variables that are significantly associated with KD, further investigation into the development of a preoperative risk scoring system that can accurately predict KD in the clinical setting is encouraged. PROSPERO registration no.: CRD42022299795 (https://www.crd.york.ac.uk/PROSPERO/).

Emerging Technologies within Spine Surgery

“…In a large metaanalysis conducted by Azimi et al, patients with cervical pathology had increased T1 slope (healthy 24.5 • , symptomatic 25.7 • ) and cSVA (healthy 18.7 • , symptomatic 22.7 • ) relative to an asymptomatic control group [18]. Additionally, an elevated T1 slope and cSVA predict postoperative kyphotic deformity as the center of the head mass is anteriorly pushed [19,20]. A similar metric, the center gravity of the head to C7 SVA (CGH-C7SVA), is also associated with increased risk of postoperative kyphotic failure following laminoplasty [20].…”

“…Additionally, an elevated T1 slope and cSVA predict postoperative kyphotic deformity as the center of the head mass is anteriorly pushed [19,20]. A similar metric, the center gravity of the head to C7 SVA (CGH-C7SVA), is also associated with increased risk of postoperative kyphotic failure following laminoplasty [20]. Lastly, the occipital cervical angle (OCI) is a critical measurement in one's ability to maintain a normal gaze with increased OCI associated with the presence and progression of ASD [21].…”

Role of Posterior Longitudinal Ligament Complex in Spinal Deformity Secondary to Surgical Resection of the Intradural Tumor

“…Laminoplasty is suggested as an alternative option because of its advantages in maintaining the motion of the cervical spine while maintaining the integrity of the posterior neck muscles and preventing epidural scar formation 26,32 . However, many reports have highlighted that laminoplasty can result in radiological kyphotic changes after surgery, although the risk is lower than that with laminoplasty alone 33,34 . The surgical technique allows wide exposure of the spinal canal, and it can easily be extended intraoperatively caudally, or rostrally.…”

“… 26 , 32 However, many reports have highlighted that laminoplasty can result in radiological kyphotic changes after surgery, although the risk is lower than that with laminoplasty alone. 33 , 34 The surgical technique allows wide exposure of the spinal canal, and it can easily be extended intraoperatively caudally, or rostrally. On the other hand, the disadvantages of this technique include possible extradural scar formation, loss of posterior spinal column integrity, and spinal instability and deformity.…”

Change of cervical flexion range of motion influences postoperative sagittal alignment of the cervical spine after laminoplasty

“…The cervical spine range of motion (ROM) refers to the change in cervical lordosis (CL) in flexion and extension compared with the neutral position. Recent studies have reported that preoperative cervical ROMs are important predictors for changes in cervical sagittal alignment (CSA) and clinical outcomes after cervical LMP [ 3 – 9 ]. Fujishiro et al [ 4 ] speculated that a large cervical flexion range of motion (Flex ROM) indicated that posterior neck muscular-ligament complex (PMLC) forces restricting motion toward the kyphotic position were weak, and Lee et al [ 5 ] thought that a small cervical extension range of motion (Ext ROM) indicated the low contraction reserve of PMLC.…”