Surgical Approaches for the Treatment of Multilevel Cervical Ossification of the Posterior Longitudinal Ligament: Results of a Decision Analysis

Highlights

• Outcome prediction for surgical management of symptomatic ossification of the posterior longitudinal ligament (OPLL) remains challenging.

• The present decision analysis sought to determine health care quality of life among the various surgical approaches for OPLL using complication and quality of life data from the existing literature.

• Anterior cervical approaches were associated with the highest complication rates.

• Laminoplasty and laminectomy alone were associated with the highest and lowest long term quality adjusted life year, respectively.

Background

Ossification of the posterior longitudinal ligament (OPLL) often leads to cervical myelopathy. Although multiple procedures have been shown to be effective in the treatment of OPLL, outcomes are less predictable than in degenerative cervical myelopathy, and surgery is associated with high rates of complications and reoperation, which affect quality of life. In this study, we performed a decision analysis using postoperative complication data and health-related quality of life (HRQoL) utility scores to assess the average expected health utility and 5-year quality-adjusted life years (QALYs) associated with the most common surgical approaches for multilevel cervical OPLL.

Methods

We searched Medline, EMBASE, and the Cochrane Library for relevant articles published between 1990 and October 2017. Meta-analytically pooled complication data and HRQoL utility scores associated with each complication were evaluated in a long-term model.

Results

The overall incidence of perioperative complications ranged from 6.2% for laminectomy alone to 11.0% for anterior decompression and fusion. Revision surgery for hardware/fusion failure or progression was highest for laminectomy alone (3.0%) and lowest for laminectomy and fusion (1.6%). Laminoplasty resulted in the highest 5-year QALYs gained, compared with laminectomy and anterior approaches (P < 0.001). There was no significant difference in QALY gained between laminectomy-fusion and laminoplasty.

Conclusion

The results suggest that owing to the higher rates of complications associated with anterior cervical approaches, laminoplasty may result in improved long-term outcomes from an HRQoL standpoint. These findings may guide surgeons in cases where either procedure is a reasonable option.

Introduction

Ossification of the posterior longitudinal ligament (OPLL) is characterized by progressive hypertrophy and mineralization of the posterior longitudinal ligament, eventually resulting in the formation of ossification centers with active bone marrow and frank bone formation.1, 2 It typically presents as myelopathy in middle-aged or elderly individuals. It is most common among eastern Asian communities, with prevalence rates are as high as 4.3% in the Japanese population over age 30, whereas the rates among non-Asian populations are considerably lower and are estimated at 0.1% to 1.7%.³ The pathogenesis is believed to be multifactorial, and a growing body of research suggests that there is a strong genetic component, with association of several genes involved in processes such as collagen formation, bone metabolism, and endochondral ossification.4, 5, 6, 7, 8

Symptomatic OPLL requiring surgical intervention represents a unique subset of cervical myelopathy patients as a result of the morphologic complexities of the OPLL mass, challenges associated with directly excising OPLL, and patient-related factors. Morphologically, there are 4 distinct radiographic subtypes of OPLL, which can influence surgical decision making: 1) continuous, single OPLL mass spanning 2 or more vertebrae; 2) segmental (most common), fragmented lesions posterior to the vertebral bodies that do not fully cross the disc spaces; 3) mixed type, a combination of continuous and segmental; 4) other, ossification posterior to the disc.⁹ Surgical approaches include anterior decompression and fusion, as well as various posterior decompression procedures with or without fusion. Anterior approaches generally involve varying degrees of corpectomy to access to the OPLL mass and subsequent strut graft or cage placement for vertebral column reconstruction. Posterior approaches (laminectomy, laminectomy with instrumented fusion, and laminoplasty) provide indirect decompression because the OPLL mass is left untouched. Each of these 4 major surgical approaches has a unique set of advantages and disadvantages, and the decision to use 1 approach over another is often dictated by prior surgeon experience and patient-specific characteristics (e.g., kyphotic deformity requiring an anterior procedure).

Numerous studies have shown that the anterior and posterior approaches are both effective in the treatment of OPLL-related cervical myelopathy, although the precise choice of procedure has long been a matter of debate.¹⁰ Although the heterogeneity associated with OPLL-related myelopathy makes cases of true clinical equipoise uncertain, there are often situations where multiple surgical approaches are feasible for a given lesion. Prior studies comparing 2 or more procedures head-to-head have generally made comparisons based on operative metrics and myelopathy scores, such as the Japanese Orthopedic Association myelopathy scale (JOA) or Nurick grade. However, surgery for OPLL is associated with high rates of complications; if complication rates vary between surgical approaches, health-related quality of life (HRQoL) should also vary and may not be reflected in neurologic outcome measures.¹¹

In this study, we attempted to compare the 4 major surgical approaches to OPLL-related cervical myelopathy (posterior laminectomy, posterior laminectomy and fusion, laminoplasty, and anterior decompression/fusion) by analyzing postoperative complication data from the published literature, in conjunction with utility scores, to determine the average expected utility and 5-year quality-adjusted life years (QALYs) gained from each procedure.