title: Open door expansive laminoplasty and postoperative axial symptoms: a comparative study between two different procedures.
abstract: METHODS
  Retrospective cohortObjective: To determine if there are differences in important clinical outcomes between patients treated with a "preservation of the unilateral posterior muscular-ligament complex (PMLC) procedure" and a "hinge side anchoring procedure (HSAP)" for the treatment of cervical spondylotic myelopathy (CSM).
  
  
  METHODS
  Nine hundred and forty-six patients underwent the above procedures for treatment of CSM between January 2006 and December 2009. Five hundred and fifty-two (58%) subjects met study criteria and 136 were analyzed (76% unavailable for follow-up). One group (70 patients) received a "preservation of unilateral PMLC procedure" and another group (66 patients) received an HSAP. The rate and severity of postoperative axial symptoms were assessed, and the changes of cervical-spine curvature and postoperative decompression were measured.
  
  
  RESULTS
  The mean time to follow-up in the preservation of unilateral PMLC group was 6.9 months (range, 6-8 months) and the HSAP group was 6.4 months (6-8 months). The overall rate of any axial symptoms (AS) among all subjects was 35%. No AS was reported in 45.7% of the preservation of unilateral PMLC group and 23.8% of the HSAP group (P = .008). Severe AS was reported in 4.3% and 11.1% of patients per group, respectively (P = .14). Cervical spinal lordosis was improved in the unilateral PMLC group and decreased in the HSAP group. The risk of losing lordosis was more than two times higher in the HSAP group compared with the unilateral PMLC group (70% and 34%, respectively; P < .001).
  
  
  CONCLUSIONS
  Differences were observed between the two groups; however, a high loss to follow-up rate weakens the findings. Cervical expansive laminoplasty with preservation of unilateral PMLC may have the advantage of a lower rate of postoperative AS and maintenance of cervical spinal lordosis compared with the HSAP group.
authors.affiliation: Department of Orthopaedic Surgery, Institute of Spine Surgery, Peking University Third Hospital, Beijing, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Sun
authors.forename: Fengshan
authors.initials: F
authors.lastname: Zhang
authors.forename: Shaobo
authors.initials: S
authors.lastname: Wang
authors.forename: Li
authors.initials: L
authors.lastname: Zhang
authors.forename: Shengfa
authors.initials: S
authors.lastname: Pan
authors.forename: Miao
authors.initials: M
authors.lastname: Yu
authors.forename: Sujun
authors.initials: S
authors.lastname: Qiu