Pullout test in expansive unilateral open-door laminoplasty of the cervical spine with OsteoMed M3 plate and screws: the screw orientation matters / 南方医科大学学报

<p><b>OBJECTIVE</b>To study the impact of screw orientation on the pullout strength of OsteoMed M3 titanium screws in expansive unilateral open-door laminoplasty of the cervical spine.</p><p><b>METHODS</b>Six fresh human cervical spine specimens were randomly numbered and OsteoMed M3 plate and screws were used for an expansive unilateral open-door laminoplasty. The screws were inserted in the lateral mass at different extraversion angles (0°, 30° and 45°). The maximum pullout strength was tested on the ElectroForce material testing machine.</p><p><b>RESULTS</b>The maximum pullout strength was 81.60∓7.33 N, 150.05∓15.57 N, and 160.08∓17.77 N in extraversion angle 0°, 30°, and 45° groups, respectively. The maximum pullout strength was significantly less in extraversion angle 0° group than in 30° and 45° groups (P<0.05), but similar in the latter two groups.</p><p><b>CONCLUSION</b>The pullout strength of the screws inserted at an extraversion angle over 30° provides stronger fixation than an angle of 0° in the unilateral open-door laminoplasty using OsteoMed M3 titanium plate and screws.</p>

Clinical application of expansive unilateral open-door laminoplasty of the cervical spine with OsteoMed M3 plate and screws / 南方医科大学学报

<p><b>OBJECTIVE</b>To introduce a new technique using OsteoMed M3 titanium plate and screws for fixation of the posterior elements in the open position after expansive unilateral open-door laminoplasty and evaluate its clinical effect.</p><p><b>METHODS</b>Sixteen patients with multilevel cervical disc herniation and canal stenosis were treated with an expansive unilateral open-door laminoplasty using OsteoMed M3 plate and screws, and the follow-up period lasted for over 6 months.</p><p><b>RESULTS</b>Most of the patients had marked neurological improvement after the surgery. The mean Japanese Orthopaedic Association (JOA) score of the patients increased significantly from 9.06-/+2.380 (range 5 to 13) before surgery to 13.63-/+1.408 (range 11 to 16) at the final follow-up (P<0.005), with a mean recovery rate of 57.5%. One patient without postoperative neurological improvement underwent an additional anterior multilevel corpectomy. Bone fusion of the surgical lamina was achieved in all the cases without canal stenosis.</p><p><b>CONCLUSION</b>Unilateral open-door laminoplasty with OsteoMed M3 titanium plate and screw fixation can effectively maintain the expansion of the spinal canal and resist closure while preserving the spinal alignment and stability. This modified technique is easy to perform and is associated with a low complication rate.</p>