Association between anterior bone loss and anterior heterotopic ossification in hybrid surgery

Clinical management of bone loss in cervical total disc arthroplasty: literature review and treatment recommendations

PURPOSE

Cervical total disc replacement (cTDR) has been established as an alternative treatment for degenerative cervical radiculopathy and myelopathy. While the rate of complications for cTDR is reasonably low, recent studies have focused on bone loss after cTDR. The purpose of this work is to develop a clinical management plan for cTDR patients with evidence of bone loss. To guide our recommendations, we undertook a review of the literature and aimed to determine: (1) how bone loss was identified/imaged, (2) whether pre- or intraoperative assessments of infection or histology were performed, and (3) what decision-making and revision strategies were employed.

METHODS

We performed a search of the literature according to PRISMA guidelines. Included studies reported the clinical performance of cTDR and identified instances of cervical bone loss.

RESULTS

Eleven case studies and 20 cohort studies were reviewed, representing 2073 patients with 821 reported cases of bone loss. Bone loss was typically identified on radiographs during routine follow-up or by computed tomography (CT) for patients presenting with symptoms. Assessments of infection as well as histological and/or explant assessment were sporadically reported. Across all reviewed studies, multiple mechanisms of bone loss were suspected, and severity and progression varied greatly. Many patients were reportedly asymptomatic, but others experienced symptoms like progressive pain and paresthesia.

CONCLUSION

Our findings demonstrate a critical gap in the literature regarding the optimal management of patients with bone loss following cTDR, and treatment recommendations based on our review are impractical given the limited amount and quality evidence available. However, based on the authors' extensive clinical experience, close follow-up of specific radiographic observations and serial radiographs to assess the progression/severity of bone loss and implant changes are recommended. CT findings can be used for clinical decision-making and further follow-up care. The pattern and rate of progression of bone loss, in concert with patient symptomatology, should determine whether non-operative or surgical intervention is indicated. Future studies involving implant retrieval, histopathological, and microbiological analysis for patients undergoing cTDR revision for bone loss are needed.

Cervical Disc Arthroplasty for the Treatment of Noncontiguous Cervical Degenerative Disc Disease: Results of Mid- to Long-Term Follow-up

OBJECTIVE

The long-term results of cervical disc arthroplasty (CDA) for noncontiguous cervical degenerative disc disease (CDDD) are still uncertain. Moreover, it is unclear whether CDA delays or avoids the degeneration of the intermediate segment (IS), leading to controversy in the field. Therefore, this study aimed to investigate the mid- to long-term clinical and radiographic outcomes of CDA in treating noncontiguous CDDD and to explore whether the IS degenerated faster after CDA than other non-surgically treated adjacent segments.

METHODS

We retrospectively analyzed patients with noncontiguous CDDD who underwent CDA in our department between January 2008 and July 2018. The patients were divided into the CDA and hybrid surgery (HS) groups, and clinical and radiographic outcomes were evaluated at routine postoperative intervals. Clinical outcomes were assessed using the Japanese Orthopaedic Association (JOA), neck disability index (NDI), and visual analogue scale (VAS), while radiographic outcomes included cervical lordosis (CL), C2-C7 range of motion (ROM), segmental ROM, and disc angle (DA) at the arthroplasty level. Complications were also evaluated.Pre- and postoperative values were compared using paired t-tests or Wilcoxon rank-sum tests. Independent Student t-tests or Mann-Whitney U tests analyzed continuous data between CDA and HS groups, while chi-square or Fisher exact tests assessed categorical data.

RESULTS

Sixty-four patients with noncontiguous CDDD, with 31 in the CDA group and 33 in the HS group, were evaluated. The mean follow-up time was over 70 months. The most frequently involved levels were C4/5 and C5/6. Both groups showed significant improvements in JOA, NDI, and VAS values after surgery. Although CL was maintained, the CL in the CDA group was consistently lower than that in the HS group (p < 0.05). There was a significant decrease in C2-C7 ROM (p < 0.05), but at the last follow-up, the C2-C7 ROM in the CDA group was greater than that in the HS group (p < 0.05). At the last follow-up, 44.3% of arthroplasty levels had developed heterotopic ossification (HO), and 48.45% had developed anterior bone loss (ABL). In addition, adjacent segment degeneration (ASDeg) was observed in the IS (22.7%), superior adjacent segment (20.6%)and inferior adjacent segment (21.9%).

CONCLUSION

CDA or CDA combined with fusion are viable treatments for noncontiguous CDDD, with satisfactory outcomes after mid-to-long-term follow-up. ASDeg is similar in non-surgical segments after 70 months of follow-up. ROM of the IS issimilar to preoperative levels, indicating CDA does not increase the risk of IS degeneration.

Fatty infiltration in cervical extensor muscle: is there a relationship with cervical sagittal alignment after anterior cervical discectomy and fusion?

Purpose

To investigate the relationship between the preoperative paraspinal Goutalier grade of fatty infiltration and postoperative cervical sagittal alignment in patients undergoing anterior cervical discectomy and fusion (ACDF).

Methods

A total of 101 patients who underwent single-level ACDF with the Zero-profile implant system between March 2011 and April 2020 were included in this study. Cervical sagittal alignment parameters, including the C2-C7 Cobb angle, functional spinal unit (FSU) angle, cervical sagittal vertical axis (SVA), and T1 slope (T1S), were assessed. Preoperative magnetic resonance images were used to classify patients according to Goutalier grade. Clinical outcomes including Neck Disability Index (NDI) scores, Japanese Orthepaedic Association (JOA) scores and Visual Analogue Scale (VAS) scores were collected and analyzed.

Results

According to the Goutalier grade, 33 patients were classified as Goutalier 0–1 (Group A), 44 were classified as Goutalier 1.5–2 (Group B), and 24 were classified as Goutalier 2.5–4.0 (Group C). The mean age among the three groups showed significant differences (P = 0.007). At the last follow-up, the C2-C7 Cobb angle, FSU angle, and T1S improved after the surgery among the groups. Although there were varying degrees of loss of curvature among the different groups during the follow-up period, the postoperative cervical sagittal alignment parameters demonstrated no statistical differences among the three groups (P > 0.05). In addition, patients in all groups experienced significant relief of their symptoms, and the clinical scores were comparable among the groups (P > 0.05).

Conclusion

The complex nature of anterior cervical surgery requires surgical attention both in decompression and sagittal alignment. Our study demonstrates satisfactory postoperative cervical sagittal alignment of patients despite different grades of fatty infiltration of the multifidus muscle following single-level ACDF. Based on our results, the improvement and maintenance of cervical sagittal alignment after ACDF remains a complex problem that spine surgeons should consider before surgery.

The impact of smoking on outcomes following anterior cervical fusion-nonfusion hybrid surgery: a retrospective single-center cohort study

BACKGROUND

There is mixed evidence for the impact of cigarette smoking on outcomes following anterior cervical surgery. It has been reported to have a negative impact on healing after multilevel anterior cervical discectomy and fusion, however, segmental mobility has been suggested to be superior in smokers who underwent one- or two-level cervical disc replacement. Hybrid surgery, including anterior cervical discectomy and fusion and cervical disc replacement, has emerged as an alternative procedure for multilevel cervical degenerative disc disease. This study aimed to examine the impact of smoking on intermediate-term outcomes following hybrid surgery.

METHODS

Radiographical and clinical outcomes of 153 patients who had undergone continuous two- or three-level hybrid surgery were followed-up to a minimum of 2-years post-operatively. The early fusion effect, 1-year fusion rate, the incidence of bone loss and heterotopic ossification, as well as the clinical outcomes were compared across three smoking status groups: (1) current smokers; (2) former smokers; (3) nonsmokers.

RESULTS

Clinical outcomes were comparable among the three groups. However, the current smoking group had a poorer early fusion effect and 1-year fusion rate (P < 0.001 and P < 0.035 respectively). Both gender and smoking status were considered as key factors for 1-year fusion rate. Upon multivariable analysis, male gender (OR = 6.664, 95% CI: 1.248-35.581, P = 0.026) and current smoking status (OR = 0.009, 95% CI: 0.020-0.411, P = 0.002) were significantly associated with 1-year fusion rate. A subgroup analysis demonstrated statistically significant differences in both early fusion process (P < 0.001) and the 1-year fusion rate (P = 0.006) across the three smoking status groups in female patients. Finally, non-smoking status appeared to be protective against bone loss (OR = 0.427, 95% CI: 0.192-0.947, P = 0.036), with these patients likely to have at least one grade lower bone loss than current smokers.

CONCLUSIONS

Smoking is associated with poor outcomes following hybrid surgery for multilevel cervical disc disease. Current smokers had the poorest fusion rate and most bone loss, but no statistically significant differences were seen in clinical outcomes across the three groups.