Objective To clarify the relationship between the laminoplasty opening size (LOS), the laminoplasty opening angle (LOA) and the increase in sagittal canal diameter (SCD) and to predict the amount of canal enlargement during open-door cervical laminoplasty (ODCL). Methods Formula describing the relationship between LOS and LOA, the increase in SCD was deduced. The parameters of pre-and postoperative computed tomography scans of 36 patients who had undergone laminoplasty surgery were measured by picture archiving and communication system (PACS) software, and the amount of canal enlargement of these patients was predicted when the opening size of laminoplasty was 8, 10, 12, 14 and 16 mm according to the formula. Results For equivalent LOS, the amount of canal enlargement with each opening size differed throughout the cervical region. When the C3-C7 LOS was 10 mm the SCD increased [4.1 mm, and the canal area increased in C3-C6 [88 mm 2 , and the canal area increased in C7 [ 80 mm 2 .When the C3-C7 LOS was 12 mm, the SCD increased [5.2 mm, and the canal area increased in C3-C6 [104 mm 2 , and the canal area increased in C7 [ 94 mm 2 . Conclusion Formula accurately showed the relationship between the LOS and the increase in SCD achieved by ODCL. The amount of canal enlargement following ODCL could be predicted by the formula. LOS of 10-12 mm at C3-C7 might be optimal during ODCL.

Rationale:Transforaminal lumbar interbody fusion (TLIF) is an effective treatment for patients with degenerative lumbar disc disorder. Contralateral radiculopathy, as a complication of TLIF, has been recognized in this institution, but is rarely reported in the literature.Patient concerns:In this article, we report 2 cases of contralateral radiculopathy after TLIF in our institution and its associated complications.Diagnoses:In the 2 cases, the postoperative computed tomography (CT) and magnetic resonance image (MRI) showed obvious upward movement of the superior articular process, leading to contralateral foraminal stenosis.Interventions:Revision surgery was done at once to partially resect the opposite superior facet and to relieve nerve root compression.Outcomes:After revision surgery, the contralateral radiculopathy disappeared.Lessons:Contralateral radiculopathy is an avoidable potential complication. It is very important to create careful preoperative plans and to conscientiously plan the use of intraoperative techniques. In case of postoperative contralateral leg pain, the patients should be examined by CT and MRI. If CT and MRI show that the superior articular process significantly migrated upwards, which leads to contralateral foraminal stenosis, revision surgery should be done at once to partially resect the contralateral superior facet so as to relieve nerve root compression and avoid possible long-term impairment.

Many surgical procedures have been developed for the treatment of post-traumatic thoracolumbar kyphosis. But there is a significant controversy over the ideal management. The aim of this study was to illustrate the technique of modified grade 4 osteotomy for the treatment of post-traumatic thoracolumbar kyphosis and to evaluate clinical and radiographic results of patients treated with this technique. From May 2013 to May 2018, 42 consecutive patients experiencing post-traumatic thoracolumbar kyphosis underwent the technique of modified grade 4 osteotomy, and their medical records were retrospectively collected. Preoperative and postoperative sagittal Cobb angle, visual analog scale (VAS), Oswestry disability index (ODI), and American Spinal Injury Association (ASIA) were recorded. The average follow-up period was 29.7 ± 14.2 months. The operation time was 185.5 ± 26.8 minutes, the intraoperative blood loss was 545.2 ± 150.1 mL. The Cobb angles decreased from 38.5 ± 3.8 degree preoperatively to 4.2 ± 2.6 degree 2 weeks after surgery ( P < .001). The VAS reduced from 6.5 ± 1.1 preoperatively to 1.5 ± 0.9 at final follow-up ( P < .001), and the ODI reduced from 59.5 ± 15.7 preoperatively to 15.9 ± 5.8 at final follow-up ( P < .001). Kyphotic deformity was successfully corrected and bony fusion was achieved in all patients. Neurologic function of 7 cases was improved to various degrees. Modified grade 4 osteotomy, upper disc, and upper one-third to half of pedicle are resected, is an effective treatment option for post-traumatic thoracolumbar kyphosis. However, the long-term clinical effect still needs further studies.

Rationale:The kyphosis caused by old osteoporotic vertebral compression fracture usually requires osteotomy to correct it. Various osteotomy techniques have been reported, but each has its own advantages and disadvantages.Patient concerns:We reviewed 2 cases of old osteoporotic vertebral compression fractures with kyphosis in our hospital. One patient complained of persistent low-back pain, another patient complained of low-back pain and weakness of both lower extremities.Diagnosis:Old osteoporotic vertebral compression fractures with kyphosis were diagnosed based on computer tomography and magnetic resonance imaging.Interventions:We performed modified grade 4 osteotomy for 2 patients.Outcomes:Both patients said significant improvement in preoperative symptoms, and x-ray showed that the kyphosis was corrected. Both patients were satisfied with the treatment at the last follow-up, and the kyphosis was not aggravated.Lessons:Modified grade 4 osteotomy is an effective option for the treatment of old osteoporotic fracture with kyphosis. It can restore the spine sequence and achieve better clinical result.

Purpose To clarify the relationship between laminoplasty opening angle (LOA) and the increase in sagittal canal diameter (SCD) in double-door cervical laminoplasty (DDCL) and to predict the increase in SCD using the resulting formula. Methods We analyzed 20 patients with multilevel cervical spondylotic myelopathy who underwent DDCL between September 2010 and January 2013. The pre-and post-operative parameters of the cervical spinal canal were measured by computed tomography. We deduced a formula describing the relationship between LOA and the increase in SCD and used it to predict the increase in SCD of these patients as LOA increased. Results When the C3-C7 LOA was 25°-45°, the magnitude of the increase in SCD was notable (increases of 3.08-5.6 mm compared with the pre-operative SCD). When the C3-C7 LOA was more than 45°, the magnitude of the increase in SCD was relatively smaller; the increase in C3-C7 SCD with a 55°LOA was merely 0.4 mm more than with a 45°LOA. When LOA was 30°at C3-C6 or 40°a t C7, the increase in SCD was more than 4 mm. When the C3-C6 LOA was 40°, SCD increased by more than 5 mm. ConclusionsThe formula accurately showed the relationship between LOA and the increase in SCD in DDCL. Based on the LOA, increases in SCD following C3-C7 laminoplasty can be accurately predicted using this formula. This enables DDCL based on accurate individual LOAs, which prevents inadequate or excessive opening.