Bone fusion rate in the thoracic and lumbar spine after laminoplasty with laminar screws.

Abstract

Retrospective clinical study. The purpose of this study was to determine the bone fusion rate after laminoplasty with laminar screws. There are many procedures, mostly with miniplates and screws, to repair an opened lamina after surgery for intraspinal pathology. Laminoplasty with laminar screws is an alternative procedure; however, the surgical outcome of this procedure has not been reported before. Laminoplasty with laminar screws was performed in 40 consecutive patients (male to female ratio=18:22; age, 47.4±13.6 yr) after surgery for intradural pathology. The lamina flap, which was opened with a high-speed drill or Kerrison punch, was reattached to the host bone with bilateral laminar screws. The bony fusion was assessed with computed tomographic scans that were taken 14.1±6.4 months postoperatively. If the gap between the host bone and the grafted lamina was filled up with a bony bridge, it was regarded as "fused." The fusion rate was assessed in terms of the hemilamina, the operated level, and the patient. The operated level was considered fused when at least 1 side of the hemilamina was completely fused to the host bone. Fusion success for a patient was defined as "all operated levels were fused." The follow-up period was 40.7±13.8 months. Screw fixation was successfully achieved in 97.7% (150/154 hemilaminae, 77 levels) of the hemilaminae. Solid bony fusion was achieved in 56.7% (85/150) of the hemilaminae, 75.3% (58/77) of the operated levels, and 67.5% (27/40) of the patients. Screw breakage or displacement of the grafted laminae was not observed during the follow-up period. Laminoplasty with laminar screws had a 67.5% fusion rate, and migration of the grafted laminae was not observed in any of the patients probably due to additional fibrous unions. 4.