Anterior cervical interbody fusion with hydroxyapatite graft: clinical and radiological analysis of graft breakage.

Study Design: Prospective longitudinal cohort.
Objective: To evaluate the efficacy of hydroxyapatite (HA) grafts in combination with cervical plates in terms of fusion, restoration, and maintenance of cervical lordosis and to compare clinical and radiologic outcomes of patients who experienced graft breakage with patients who did not.
Summary of Background Data: The most common complication related to the use of HA graft for cervical anterior fusion is graft breakage. However, the implication of graft breakage in terms of loss of graft height, cervical alignment, plate migration, and clinical outcomes has not been adequately evaluated.
Methodology: A prospective study of 40 patients who underwent anterior cervical fusion in which HA graft and plate systems were used. Clinical and radiologic assessments were made 1 month after surgery and again at the final follow-up.
Results: At the final follow-up evaluation, 80% of patients had an excellent clinical outcome, 15% had a good outcome, and 5% had a fair outcome based on Odom's classification. All patients achieved lordotic alignment in the immediate postoperative period. Graft breakage was observed in 25% of cases. Patients who experienced HA block breakage have 21 times more chance to have intervertebral height loss greater than 2 mm, 4.9 times more likely to undergo loss of cervical alignment exceeding 3 degrees, and 12.4 times more likely to present migration of the plates when compared to patients who had normal HA grafts.
Conclusion: Despite the positive clinical results observed in this study, breakage of HA grafts was a common complication occurring in 25% of patients. Graft breakage was associated with strut height loss of more than 2 mm, loss of cervical alignment exceeding 3 degrees and a higher rate of plate migration. These changes related to the HA graft breakage demonstrate the necessity to continue searching for better grafting methods to perform cervical interbody fusion.