[Analysis of clinical efficacy of unilateral open-door cervical laminoplasty combined with foraminotomy for cervical ossification of posterior longitudinal ligament].

OBJECTIVE: To explore the clinical efficacy of unilateral open-door laminoplasty combined with foraminotomy for cervical ossification of posterior longitudinal ligament(OPLL). METHODS: The clinical data of 45 patients with OPLL underwent surgical treatment between September 2011 and September 2015 were retrospectively analyzed. There were 26 males and 19 females with a mean age of 53.6 years old(ranged from 28 to 71 years). Among them, 24 cases received the surgery of unilateral open-door cervical laminoplasty combined with foraminotomy(combined group), and 21 cases received a single unilateral open-door cervical laminoplasty(single group). Operation time, intraoperative blood loss, complications including C5 nerve root palsy and axial symptoms were compared between two groups. Pre-and post-operative Japanese Orthopedic Association(JOA) score, improvement rate of neurological function, Neck Disability Index(NDI) score, and cervical Cobb angle were recorded and analyzed between the two groups. RESULTS: All the patients were followed up for 12-24 months, with an average of (14.3±2.8) months for combined groups and (13.7±3.1) months for single group, and no significant difference was found between the two groups(P>0.05). There was no significant difference in operation time and intraoperative blood loss between two groups(P>0.05). Postoperative JOA scores obtained obvious improvement in all patients(P<0.05). However, there was no significant difference between two groups for the improvement rate of neurological function(P>0.05). At final follow-up, NDI scores of combined group and single group were 13.6±1.8 and 16.1±2.4 respectively, there was significant difference between two groups(P<0.05). The incidence of C5 nerve root palsy was lower in combined group(4.2%) than that of single group (28.6%). There was no significant difference in incidence rate of axial symptoms between two groups(P>0.05). There was no significant difference in cervical Cobb angle between pre-and post-operative conditions, or between two groups(P>0.05). CONCLUSIONS: Unilateral open-door cervical laminoplasty combined with foraminotomy is an effective method to treat cervical OPLL, which could provide sufficient decompression of spinal cord and nerve root, prevent the C5 nerve root palsy.

[Pedicle exposure technique for atlas screw fixation:a radiological research].

OBJECTIVE: To investigate the meaning of pedicle exposure technique for screw fixation on atlas with the vertebral groove height less than 4 mm by using reconstructive computed tomography. METHODS: From April 2015 to June 2015, 84 pedicles of 51 patients with groove heights less than 4 mm were studied by digital reconstruction respectively. Parameters of atlas pedicle screw fixation were measured. RESULTS: Among the 51 cases, the vertebral groove height was (3.28±0.51) mm. Lateral mass heights, lateral mass widths and the transition area heights between lateral mass and posterior arch were fit for 3.5 mm screw implanting. Ideal pedicle screw trajectory lengths from 0° to 15° (0°, 5°, 10°, 15°) were (27.36±1.81), (27.01±1.68), (27.07±1.75), (27.48±1.72) mm, exposed trajectory lengths from 0° to 15°(0°, 5°, 10°, 15°) were(23.44±1.79), (23.87±1.84), (24.58±1.89), (25.56±2.01) mm, trajectory length of lateral mass was (20.78±2.05) mm. The mean CT values on 5 sections through pedicle trajectory and lateral mass trajectory were (701.89±141.48) HU and (599.11±137.33) HU, respectively. There were no significant differences between ideal pedicle trajectory lengths from 0° to 15°(P>0.05). Exposed trajectory lengths was significantly increased accompanying with medial angles increasing (P<0.05), and was longer than trajectory lengths of lateral mass (P<0.05). CT value of pedicle screws was higher than CT value of lateral mass screws significantly (P<0.01). CONCLUSIONS: Screws can be implanted in atlas with vertebral groove height less than 4 mm by using pedicle exposure technique. Few trajectory lengths will be sacrificed with favorable pull out strength due to adequate bone mass purchased.