TREATMENT OF TRAUMATIC CERVICAL SPINE INSTABILITY WITH INTERBODY FUSION CAGES. A PROSPECTIVE CONTROLLED STUDY

Abstract

Introduction The purpose of this prospective controlled study was to define indications and analyse the clinical and radiographic results of cages in the surgical treatment of traumatic cervical spine instability.

Methods 53 patients were treated by monosegmental anterior discectomy and interbody fusion using either autologous tricortical iliac crest bone graft and cervical spine locking plate (CSLP) (bone graft group, n= 26) or Syncage-C (Synthes) filled with autologous cancellous bone grafts and CSLP (cage group n=27). Indications for surgery were traumatic cervical spine instability were classified by the cervical fracture classification of Blauth et al¹ as B1, B2, B3, C2 or C3 fractures. Intraoperative parameters (operative time, blood loss radiation time and intra- and perioperative complications) were documented. Prior to surgery and at follow-up (6 and 12 months) evaluation included measurement of neck pain, shoulder/arm pain and Neck Pain Disability Index (NPDI). Neurological function was assessed using the ASIA scale. Radiographic evaluation included plain X-rays, flexion-extension views and CT-scans. Patient satisfaction was measured on a five-point Likert scale.

Results There was no statistically significant difference between the two groups in the demographic data. One patient in the bone graft group was not available for the 1-year follow-up evaluation; however, all patients were available for the 2-year follow-up. Operation time was significantly shorter (p< 0.05) in the cage group (67 +/− 6 min) than in the bone graft group (78 +/− 9 min). After 6 and 12 months there was no difference between both groups in pain or NPDI, neurological and overall outcome. The neurological improvement of the two groups was not statistically different. Although the cage group showed a trend for better maintenance of lordosis after 12 months, there was no statistically significant difference between groups in all radiographic parameters. There were no implant-related complications during the follow-up. General complications included one patient with eczema due to the stiff collar (cage group) and one patient with pneumonia (cage group). Complications associated with the harvesting of iliac crest bone grafts included 14 patients (9 patients in the bone graft group, 5 patients in the cage group) with prolonged pain (> 3 months) at the donor site, one superficial wound healing problem (bone graft group) which healed under conservative treatment and one hematoma (bone graft group) which required additional surgery.

Discussion Cages offer a valid alternative to a tricortical iliac crest bone graft in the surgical treatment of mono-segmental traumatic cervical spine instability. Although there was no significant difference between the cage and the bone graft group in the functional and radiographic outcome, less donor site morbidity and a shorter operation time make cages cost effective in this selected group of patients. Although the cages are expensive, less donor site morbidity, shorter operation time and reduced hospital stay might result in cost-effectiveness of this implant.