Short-term complications and long-term results of expansive open-door laminoplasty for cervical stenotic myelopathy

Abstract

Background context: Laminoplasty has been reported to achieve good operative results for treatment of cervical stenotic myelopathy. However, long-term results and prognostic factors have not been well documented. Among postoperative complications, weakness of the shoulder girdle muscles has been reported as a particular complication of laminoplasty, but the cause is still poorly understood. Purpose: Our aim was to clarify the short-term complications and long-term operative results after unilateral open-door laminoplasty and to identify the predictors for operative outcome. Study design: We retrospectively reviewed short-term complications and long-term operative results associated with cervical stenotic myelopathy treated by unilateral open-door laminoplasty. Patient sample: There were 162 men and 42 women with an average age of 57 years who were treated by unilateral open-door laminoplasty in the two institutions. Pathogenesis of myelopathy was cervical spondylosis in 88 patients, cervical disk herniation with a narrow spinal canal in 10, and ossification of the posterior longitudinal ligament in 106. Outcome measures: Postoperative complications and their outcomes were examined clinically in 204 patients, and causes of motor paresis were sought with postoperative computed tomography after myelography. Postoperative improvement of clinical symptoms was assessed by recovery rate calculated with the scores of the Japanese Orthopaedic Scoring System in 80 patients. Methods: The occurrence rate of short-term postoperative complications, causes of motor paresis, and their outcomes were reviewed in 204 patients. Clinical condition was assessed with the Japanese Orthopaedic Scoring System, recovery rate was calculated with the score, and prognostic factors for outcome were studied in 80 patients who were followed up for 5 years or longer (average, 8 years; range, 5–17 years). Results: Occurrence rate of complications, such as muscle weakness, deep infection, closure of opened laminae, and others, was 10.8%. Muscle weakness was observed in 7.8% of the patients. However, this rate decreased in recent years. The cause of motor paresis is not known with certainty, but it may be secondary to operative trauma, posterior shift of the spinal cord, or to displacement of the lamina in the hinge side. Recovery rate of clinical symptoms was 62.1% at the final follow-up. Rates were 63.6% for cervical spondylosis, 87.1% for cervical disk herniation, and 61.3% for ossification of the posterior longitudinal ligament. There was no significant difference between pathologies. Patient age younger than 60 years at the time of operation and less than 1 year's duration of symptoms before surgery were significantly associated with recovery rate of clinical symptoms. Recovery rate was not correlated with either preoperative function judged by the Japanese Orthopaedic Association score or spinal sagittal diameter. Conclusions: The main cause of postoperative motor paresis of upper extremities is thought to be operative trauma, resulting from such procedures as air-drill and Kerrison rongeur handling. Short-term complications may decrease with the use of nontraumatic procedures. Better operative outcomes may be achieved with careful operative procedures and early operative treatment in the patients with myelopathy.