Study design: This is a prospective, consecutive series study to determine the role of the Bryan artificial cervical disc replacement to treat the isolated cervical disc herniation for Chinese patients.
Objective: To evaluate the intermediate clinical outcome and its limitations of Bryan cervical disc replacement in the management of isolated cervical disc herniation in Chinese patients. Observing neurological improvement and the radiographic finding.
Summary of background data: Most people believe that anterior cervical fusion is a factor that shall not be ignored in adjacent segment degeneration. Artificial cervical disc replacement, as a nonfusion technique, may offer a solution to this problem. The clinical outcome of cervical arthroplasty in oriental patients is not often seen in English literature. The variation of anatomic index in Asian patients was also not considered enough.
Methods: There were consecutive series of 45 patients with cervical disc herniation. The herniated disc was located at C3-4 in 2 cases, at C4-5 in 8 cases, at C5-6 in 24 cases, at C6-7 in 5 cases, at C4-5, 5-6 in 2 cases, at C3,4, 5-6 in 1 cases, and at C 5-6, 6.7 in 3 cases. There were 19 patients with myelopathy and 26 patients with radiculopathy. A total of 51 sets of Bryan cervical disc prosthesis were implanted. The follow-up ranges from 24 to 70 months. The clinical symptom and the neurological function were evaluated. The level of stableness and mobility at the implanting location were observed on dynamic radiograph postoperatively.
Results: A total of 51 Bryan cervical disc prosthesis were implanted. Single-level disc was replaced in 39 cases whereas bilevel in 6 cases. The follow-up ranges from 24 to 70 months, with an average of 35 months. Patients showed significant improvement in neurological symptoms. The JOA score (17 points) was from 10.2 increased to 15.4 at final follow-up. The neck disability index was from 43.5 reduced to 28.4 at final follow-up. The clinical success (excellent/good/fair) according to Odom' Criteria were 89.8%. The average range of motion at implant level was 9.3 degrees, postoperatively. Migration of artificial disc greater than 2 mm was not observed. Resorption at the inferior edge of anterior surface of upper vertebral body were seen in 3 patients, Two patients had II grade heterotopic ossification. One patient had a definite spontaneous fusion of treated segment after 4 years of follow-up. There was some difficulty for exact matched implant in small group patients owing to the variation of anatomic index in oriental patients.
Conclusions: Cervical arthroplasty had a good intermediate clinical outcome for oriental patients. Definite stabilization and satisfactory mobility were achieved after surgery, with significant neurological symptom improvement observed. For better matched implant, more shapes/sizes of artificial cervical disc need to be made available for the oriental patients.