An in vitro biomechanical study of a novel total cervical prosthesis (TCP) using a cadaveric model.
After evaluation of the ROM of the 14 human cadaveric cervical spines (C2-T1) (intact group), single-level subtotal corpectomy models at the C5 levels were performed. All specimens were randomized, instrumented with ACP (n = 7) and TCP (n = 7) from C4 to C6. All specimens were tested for flexion/extension, lateral bending, and axial rotation loading. The ROM of implanted segments (C4-C6) and adjacent segments (C3/C4 and C6/C7) were monitored, respectively.
TCP was found to accurately recapitulate the preoperative ROM both in the adjacent segments (C3/C4 and C6/C7) and the implanted segments (C4-C6). In the adjacent segments, no significant difference was found in ROMC3/C4 between the TCP group and聽the intact group in flexion, extension, and lateral bending. In the implanted segments, TCP preserved well the聽ROMC4-C6, with 5.29掳 in flexion, 12.27掳 in extension, 8.95掳 in right lateral bending, and 7.50掳 in left lateral bending. In contrast, the mean ROMC4-C6 in the ACP group was lower than those in the TCP group and the intact group significantly in all directions (P聽< 0.05). In addition, compared with the ACP group, the mean ROMC3-C7 in TCP group increased by 32.6%(P聽= 0.034) in flexion, 62.9%(P = 0.008) in extension, 24.8%(P > 0.05) in lateral bending, and 36.0%(P < 0.01) in rotation. Compared with the intact group, the TCP group showed moderate decrease in flexion and moderate increases in extension, lateral bending, and rotation. But no significant differences were detected (P > 0.05).
Biomechanical analyses suggest that TCP preserves ROM in the implanted segments after cervical subtotal corpectomy. TCP will not induce compensatory motion in the adjacent segments, thus may possibly help prevent adjacent segment degeneration.