Expansive laminoplasty for myelopathy in ossification of the longitudinal ligament

Cervical alignment, range of motion, and instability after cervical laminoplasty

It has been reported that flexibility of the neck decreases after cervical laminoplasty. It also is known that kyphosis can be an unfavorable result after posterior decompression surgery of the cervical spine. To examine whether a decrease in cervical mobility resulting from contracture of the cervical spine helps prevent postoperative kyphotic alignment, changes in radiographic findings after cervical expansive laminoplasty were evaluated. There was a strong correlation postoperatively between range of motion of the cervical spine and cervical lordotic alignment, namely, the more that cervical mobility was maintained, the more that cervical lordosis was preserved. This relationship was not found preoperatively. A postoperative increase in the number of unstable vertebrae was found only in a few patients and was not associated with any deterioration in clinical outcome. The current results suggest that postoperative cervical lordosis is preserved not through intervertebral soft tissue contracture or bony fusion, but through more dynamic factors such as muscles or ligaments, therefore implicating the importance of early removal of cervical orthosis and early postoperative rehabilitation.

Long-term results of expansive laminoplasty for ossification of the posterior longitudinal ligament of the cervical spine: more than 10 years follow up

Object. The authors report the long-term (more than 10-year) results of cervical laminoplasty for ossification of the posterior longitudinal ligament (OPLL) of the cervical spine as well as the factors affecting long-term postoperative course.

Methods. The authors reviewed data obtained in 92 patients who underwent cervical laminoplasty between 1982 and 1990. Three patients were lost to follow up, 25 patients died within 10 years of surgery, and 64 patients were followed for more than 10 years. Results were assessed using the Japanese Orthopaedic Association (JOA) scoring system for cervical myelopathy. The recovery rate was calculated using the Hirabayashi method. The mean neurological recovery rate during the first 10 years after surgery was 64%, which declined to 60% at the last follow-up examination (mean follow up 12.2 years). Late neurological deterioration occurred in eight patients (14%) from 5 to 15 years after surgery. The most frequent causes of late deterioration were degenerative lumbar disease (three patients), thoracic myelopathy secondary to ossification of the ligamentum flavum (two patients), or postoperative progression of OPLL at the operated level (two patients). Postoperative progression of the ossified lesion was noted in 70% of the patients, but only two patients (3%) were found to have related neurological deterioration. Additional cervical surgery was required in one patient (2%) because of neurological deterioration secondary to progression of the ossified ligament. The authors performed a multivariate stepwise analysis, and found that factors related to better clinical results were younger age at operation and less severe preexisting myelopathy. Younger age at operation, as well as mixed and continuous types of OPLL, was highly predictive of progression of OPLL. Postoperative progression of kyphotic deformity was observed in 8% of the patients, although it did not cause neurological deterioration.

Conclusions. When the incidence of surgery-related complications and the strong possibility of postoperative growth of OPLL are taken into consideration, the authors recommend expansive and extensive laminoplasty for OPLL.

Progression of ossification of the posterior longitudinal ligament following en bloc cervical laminoplasty

BACKGROUND

Ossification of the posterior longitudinal ligament often causes compressive myelopathy. Ossification is a progressive disease, and it has been reported that the area of ossification increases after decompressive surgery. However, it is uncertain how the progression of ossification affects the long-term outcome after cervical laminoplasty. This study was performed to clarify the relationship between the progression of ossification of the posterior longitudinal ligament and the clinical results following en bloc cervical laminoplasty.

METHODS

Forty-five patients who were followed for more than ten years after laminoplasty participated in this study. Radiographs and tomograms of the cervical spine of each patient were made before and after the operation and at the time of the latest follow-up. The extent of ossification in the longitudinal and sagittal axes was evaluated. Neurological function was graded with use of the Japanese Orthopaedic Association scoring system. The relationship between the progression of ossification and the score-based rate of recovery was analyzed.

RESULTS

Thirty-three (73%) of the patients had progression of ossification of the posterior longitudinal ligament after laminoplasty. Progression was frequent in patients with the mixed type of ossification and in those with the continuous type, whereas it was rare in patients with the segmental type. The patients with progression of the ossification were significantly younger than those without progression (p = 0.018). The Japanese Orthopaedic Association score improved rapidly within one year and continued to improve up to five years after surgery. The score tended to decrease thereafter. For thirteen patients, the score had worsened at the time of the latest follow-up. Three patients had neurological deterioration following an increase in the thickness of the ossification.

CONCLUSIONS

Progression of ossification of the posterior longitudinal ligament was often observed during the long-term follow-up period after laminoplasty. Young patients with mixed and continuous types of ossification had the greatest risk for progression. Preventive measures, such as the use of a wider laminar opening during the laminoplasty, should be considered for patients who are at risk for progression of ossification.

Clinical and radiological correlates of severity and surgery-related outcome in cervical spondylosis

OBJECT

The aim of this study was to determine if radiological features could be used to predict outcome in patients with cervical spondylotic myelopathy (CSM).

METHODS

The authors studied 69 patients consecutively referred to The National Hospital, Queen Square, for decompressive surgery. Data obtained from preoperative cervical spine magnetic resonance (MR) imaging studies were each analyzed on two separate occasions by two blinded radiologists. The parameters determined were signal change and the presence and severity of compression. Clinical outcome was determined by pre- and postoperative timed walks, as well as by evaluation of myelopathy disability index scores, Ranawat classification, and Nurick grades. There was good inter- and intraobserver reliability for determination of radiological data. A significant relationship was found between MR imaging signal change and surgery-related outcome, as reflected by improvement in walking parameters; however, this was confounded by the fact that signal change also related to preoperative walking parameters, and those patients for whom preoperative walking function was worse experienced greater functional improvement in walking postoperatively. The relationships between ambulatory-related data and severity or extent of spinal cord compression were less marked.

CONCLUSIONS

Cervical cord compression and intrinsic MR imaging signal change correlate with clinical severity, and, in this population, the presence of signal change was correlated with better surgery-related outcome. However, confounding factors and the lack of strong correlation indicate that these radiological measurements are insufficient to be used as a reliable tool for predicting surgery-related benefits in individual patients.

Impact of longitudinal distance of the cervical spine on the results of expansive open-door laminoplasty

STUDY DESIGN

A retrospective study in patients who underwent expansive open-door laminoplasty (ELAP) for cervical myelopathy and in whom the cervical alignment was nonlordotic at the final follow-up to analyze the correlation between the longitudinal distance of the cervical spine and surgical results.

OBJECTIVES

To determine the impact of longitudinal distance of the cervical spine on surgical results of ELAP and to propose a new concept, the redundant spinal cord, that may influence patient selection for ELAP.

SUMMARY OF BACKGROUND DATA

Results in many studies have demonstrated that postoperative cervical alignment has significant effect on surgical results, and spines that are malaligned are thought to deteriorate. The current surgical data showed that not all patients with postoperative malalignment had poor surgical results. Patients with cervical spondylotic myelopathy (CSM) tended to have better clinical results than those with ossification of the posterior longitudinal ligament (OPLL).

METHODS

Results in 70 patients who underwent ELAP for cervical myelopathy with postoperative cervical malalignment were investigated. The longitudinal distance index (LDI) was defined as the length of a vertical line between the posteroinferior edges of C2 and C7 divided by the anteroposterior diameter of C4 and was measured on lateral neutral radiographs at final follow-up. Correlation between LDI and surgical results represented by Japanese Orthopedic Association scores and percentage of recovery were analyzed statistically in each patient.

RESULTS

Patients with CSM had smaller LDI and better surgical results than those with OPLL. Weak but significant negative correlation was detected between LDI and percentage of recovery, indicating that longitudinal distance of the cervical spine may have some degree of impact on the surgical results of ELAP.

CONCLUSION

A decrease in LDI represents shortening of the cervical spine caused by multiple disc degeneration and may influence surgical results of ELAP by inducing redundancy of the spinal cord in patients with postoperative malalignment.