Preliminary Experience Using a Polyetheretherketone (PEEK) Cage in the Treatment of Cervical Disc Disease

Objective: We investigated the effectiveness of a new material, polyetheretherketone (PEEK), in a spinal cage used in performing cervical spinal fusion for the correction of cervical kyphosis.

Methods: A total of 80 patients with various cervical diseases were divided into two groups. Patients in Group A (40 patients) underwent microdiscectomy and PEEK cage fusion, and patients in Group B (40 patients) were treated with microdisectomy and autogenous iliac crest graft (AICG) fusion. We evaluated the patients for cervical lordosis, the height of the foramina, the cross sectional area of the foramina, and fusion status on the basis of x-rays. The patients' neurological and functional outcomes were assessed on the basis of the Prolo scale. Magnetic resonance imaging was also performed for spinal cord evaluation.

Results: The use of the PEEK cage in patients who undergo spinal fusion may increase cervical lordosis (mean, 2.33 +/- 3.00 mm; P = 0.03), whereas AICG fusion may not (mean, -0.84 +/- 6.69 mm; P = 0.49). The use of the PEEK cage was found to increase the height of the foramina (mean, 2.54 +/- 1.40 mm; P = 0.00) and increase its cross sectional area (mean, 40.36 +/- 23.53 mm2; P = 0.00). The height of the foramina increased only in the PEEK group postoperatively. The cross sectional area of the foramina increased in both groups postoperatively. The complication rate in patients who underwent fusion procedures with the PEEK cage was less than that in patients who underwent fusion with AICG fusion (2.50 versus 17.50%; P = 0.03). Both groups had a satisfactory fusion rate (100 versus 93.1%). The patients' postoperative Prolo scale scores were statistically better in the PEEK group (8.50 +/- 1.49 versus 7.17 +/- 2.13; P = 0.00), and more patients in the PEEK group than in the AICG group achieved excellent outcomes (66.63 versus 28.57%; P = 0.00). Because PEEK is radiotransparent on x-rays and few artifacts are seen on magnetic resonance imaging scans, it is better suited than autogenous iliac crest donor material for postoperative radiographic evaluation.

Conclusion: The PEEK cage provides solid fusion, increased cervical lordosis, and increased height and cross sectional area of the foramina. There are few complications associated with the use of this cage, and the functional and neurological outcomes are satisfactory. It also facilitates postoperative x-ray and magnetic resonance imaging evaluation. The PEEK cage is therefore a good substitute for AICG fusion in patients with cervical disc disease.