Midline T-Saw Laminoplasty for the Management of Cervical Spondylotic Myelopathy

Introduction:

Spinous process splitting laminoplasty for the management of cervical spondylotic myelopathy has been well accepted in Japan. The results in non–Japanese patients are unknown.

Objectives:

Assess the efficacy of midline 'T–saw' laminoplasty in non–Japanese patients.

Methods:

Eighteen patients underwent expansive, midline, 'T–saw' laminoplasty (C3–C7) for multi–level cervical myelopathy at a single institution. Independent clinical and radiographic evaluation at latest follow–up (mean 18 months, range 10–31 months) were performed by a single physician. In addition to a patient self–assessment questionnaire and SF–36, objective measures included physical examination, Pavlov's ratio, sagital canal diameter (CT), cord compression index, cervical lordosis, ROM and complications. Statistical comparison of pre and post operative measures was performed using a Wilcoxon signed–rank test.

Results:

Progression of myelopathy was arrested in all patients. Patients reported improvement in subjective symptoms: strength (61%), dexterity (50%), numbness (78%), pain (89%), gait (61%). Bowel/bladder compromise resolved in 5/6 patients (p=0.02). The mean Nurick score improved from 2.7 to 1.0 by the latest follow–up (p<0.001). Mean score on the Robinson pain scale improved from 2.0 to 0.89 (p=0.002). Objectively, 68% of patients with motor weakness regained normal strength (p=0.001), while 50% regained normal sensation (p=0.003). Radiographic canal expansion was verified by increased mean Pavlov ratios from 0.63 to 1.08 (p<0.001), and by direct osseous sagital CT measurements from an average of 10 mm pre–operatively to 18 mm after laminoplasty. The mean cord compression index improved from 0.49 to 0.61 (p=0.01). There was no significant change in mean cervical lordosis. Cervical F/E motion (C2 to C7) decreased from 37o to 23o (p=0.05). Neither graft dislodgment nor segmental instability were observed in any patient. Complications included: infection (1), and persistent post–operative motor root lesion (C5) (1).

Conclusions:

'T–saw' spinous process splitting laminoplasty appears to be a safe and effective method of treating multi–level cervical myelopathy by both clinical and radiographic criteria.