Effect of modified techniques in Bryan cervical disc arthroplasty.

STUDY DESIGN

A prospective, randomized study of the clinical and radiographic outcomes in patients undergoing single- and 2-level cervical arthroplasty with Bryan cervical disc (Medtronic Sofamor Danek, Memphis, TN).

OBJECTIVE

This study was designed to investigate the modified techniques of cervical arthroplasty with Bryan disc and analyze the clinical and radiologic effects.

SUMMARY OF BACKGROUND DATA

Aggravation of kyphosis is the known challenge after arthroplasty. Disc insertion angle and overmilling were reported to be factors causing kyphosis. However, few studies have performed methods to avoid these factors. Additionally, translation and length matching of prosthesis seemed to be ignored. There have been no studies regarding the effects of modified techniques for the prevention of these adverse outcomes.

METHODS

Modified techniques include change in disc insertion, reducing overmilling of endplates, the assurance of the anterior borders at the same horizontal line, and the accurate fitness of prosthesis size. Techniques described in product monograph were applied to 20 patients (control group) and modified techniques were applied to 19 patients (investigational group). Clinical and radiologic (radiograph) follow-ups of all the patients were performed before surgery and after surgery (6 months). Comparisons between the 2 groups in terms of functional spinal unit angle, shell angle, the anteroposterior displacement between the 2 metal shells in the neutral position, and the fitness of prosthesis size were performed.

RESULTS

Radiologic outcomes in investigational group were significantly superior to those in control group; clinical outcomes were similar in both groups.

CONCLUSION

The modified techniques can improve the outcomes of the cervical arthroplasty with Bryan disc and prevent the unexpected imbalance and motion of cervical spine.