Acute graft extrusion following central corpectomy in patients with cervical spondylotic myelopathy and ossified posterior longitudinal ligament

We studied the influence of surgeon experience, number of levels operated and level of the lower mortise on acute graft extrusion in patients undergoing uninstrumented one-level to three-level central corpectomy (CC) for cervical spondylotic myelopathy (CSM) or ossified posterior longitudinal ligament (OPLL). Between 1992 and 2005, 410 consecutive patients underwent one-level to three-level CC with autologous iliac (in one-level and two-level corpectomy) or fibular (in three-level corpectomy) graft. The surgeon’s experience was divided into four eras (I-IV; three eras of 100 consecutive patients each and the fourth with the last 110 patients). Eight patients (1.95%) experienced acute graft migration and seven required re-exploration. The graft extrusion rate in the first era was significantly higher than in the other three eras (6%, 1%, 1%, 0%; p = 0.01) implying a significant learning curve. The extrusion rates for one-level, two-level and three-level CC were not significantly different (3%, 1.6%, 0% respectively; p = 0.3). The extrusion rate for grafts ending in the C7 body (3/230, 1.6%) was not significantly different from the data for grafts ending in other bodies (5/180, 2.8%) (p = 0.23). There is a low incidence of acute graft migration in patients undergoing uninstrumented CC with autologous bone grafts with a significant learning curve in avoiding graft extrusion.