Nonautologous Interbody Fusion Materials in Cervical Spine Surgery

How Strong is the Evidence to Justify Their Use?

Abstract

Study Design.  

A review of the literature concerning the use of interbody fusion devices and materials in anterior cervical surgery.

Objectives. 

To examine the evidence supporting the use of interbody fusion devices as an alternative to autologous bone after anterior cervical discectomy.

Summary of Background Data.  

Concerns over the morbidity associated with harvesting autologous bone and the risk of transmissible infectious from allografts and xenografts have prompted the search for alternative methods of achieving interbody fusion. Several of these methods have been associated with an unacceptable rate of complications. The clinical and health economic implications of the widespread introduction of interbody fusion devices in the absence of sound evidence cannot be ignored.

Methods. 

A systematic review of the literature relating to cervical interbody fusion was undertaken. Studies were assessed critically with respect to their methodology, results, and conclusions.

Results. 

Thirty-two clinical studies and 10 laboratory studies were analyzed. Methodologic weaknesses were identified in the majority. Only four clinical reports were either randomized or blinded or involved independent assessment of their outcomes. Fewer than half of the studies included a valid statistical analysis. Radiologic evidence of fusion was limited in many cases. There was little evidence that nonautologous fusion devices offered a reduction in the length of hospital stay. Autologous bone was as effective as, or superior to, many other fusion devices. The early results of some new fusion techniques used alone or in combination showed promise.

Conclusions. 

There is limited evidence supporting the use of a cervical interbody fusion device in place of autologous bone. There is a need to standardize the testing of implants with good quality laboratory work preceding clinical use. Certain devices including cages, some forms of hydroxyapatite, and bone morphogenic proteins merit further study.