Objective:To explore the clinical efficacy of spinal endoscopy in the treatment of lumbar posterior ring apophysis fracture;to analyze the correlation between the improvement of clinical symptoms before and after surgery and the imaging changes of the spinal canal for providing a theoretical basis for clinical full decompression.Methods:A total of 42 patients with posterior ring apophysis fracture of lumbar 4～5 segments meeting the inclusion and exclusion criteria from Decem-ber 2015 to December 2019 were collected in the study.All patients were treated with spinal endoscopy

partial discectomy and complete resection of separated and broken bones under the transforaminal endoscope.All patients received visual analogue scale(VAS)

Oswestry disability index(ODI)

and Japanese Orthopaedic Association(JOA) scores 3 months before and after operation

and the therapeutic effect of modified MacNab was evaluated after operation.At the same time

preoperative and postoperative imaging examinations were performed to record the changes in data

and statistical data analysis was made.Results:The operation was smooth

with no open transition

dural sac tear

or nerve root injury.The operation time was 35 min to 80 min

with3 to 17 times of intraoperative fluoroscopy

and the amount of bleeding during the operation was about 10 ml to 20 mL.Postoperative imaging showed that the dural sac and nerves were completely decompressed and 42 cases of severed bone masses were completely removed.The patients were followed up after operation

and the excellent and good rate was 95.24% according to the MacNab efficacy evaluation standard.After 3 months of follow-up after operation

the VAS score decreased from(7.19±0.40) points before surgery to(2.58±0.83) points(P<0.01)

the ODI score decreased from(56.52±3.55)% before surgery to(19.83±5.00)%(P<0.01)

and the JOA score increased from(8.48±2.42) points before surgery to(21.71±2.86) points(P<0.01).There significant differences in spinal canal transverse diameter

spinal canal median sagittal diameter

and spinal canal cross-sectional area in CT before and after surgery

as well as in inter-articular diameter

spinal canal cross-sectional area

and dural sac cross-sectional area in MRI before and after operation(P<0.01).Conclusion:Firstly

spinal endoscopy can be used to treat posterior ring apophysis fracture of the 4～5 segments of the lumbar vertebrae through a safe and effective minimally invasive approach

which can achieve satisfactory clinical results.Secondly

improvement of the median sagittal diameter of the spinal canal

the inter-articular diameter

and the cross-sectional area of the spinal canal have a strong correlation with clinical efficacy before and after surgery.The improvement of imaging data can be used as a static method for judging clinical efficacy

meanwhile

accurate targeted puncture and thorough nerve decompression are also guarantees of good surgical efficacy.