Ossification foci act as stabilizers in continuous-type ossification of the posterior longitudinal ligament: a comparative study between laminectomy and laminoplasty

BACKGROUND: In multilevel ossification of the posterior longitudinal ligament (OPLL), laminectomy is an effective surgical technique; however, there is a possibility of kyphotic alignment change after surgery. Nevertheless, in the continuous type of OPLL, the ossification foci are connected and may act as stabilizers preventing alignment change. We here compare the surgical outcome of laminectomy and laminoplasty in continuous-type OPLL of the cervical spine. METHODS: Seventy-three patients who underwent cervical laminectomy or laminoplasty for continuous-type OPLL from 2004 to 2014 were enrolled. The clinical outcomes were assessed by using the neck disability index, visual analogue scale, and Japanese Orthopedic Association scoring systems. Radiological evaluation with plain lateral radiographs was performed to observe alignment changes. RESULTS: The perioperative clinical outcome with laminectomy did not differ significantly from that of laminoplasty. Kyphotic change was observed in 3 of 35 patients with laminectomy and 3 of 38 patients with laminoplasty. Although loss of lordosis was observed in both groups, the C2-7 Cobb angle, sagittal vertical axis (SVA), and T1 slope did not demonstrate significant statistical differences between laminectomy and laminoplasty. Moreover, the C2-7 SVA in the C7-included laminectomy group (33.9 ± 13.4) became greater than that in the C7-excluded laminectomy group (24.8 ± 11.3) at the final follow-up (p = 0.049). CONCLUSIONS: In continuous-type OPLL, the surgical outcome did not show any significant difference between laminectomy and laminoplasty. Laminectomy alone is also a good choice in continuous-type OPLL, similar to laminoplasty.restrictio