| Part I .An analysis on the complications associated withposterior lumbar interbody fusion cagesObjective: To review the results of posterior lumbar interbody fusion(PLIF) cages, and analyze the risky factors resulting in the complications of them. Methods: One hundred and forty five patients underwent cage PLIF were followed up from Oct 1996 to Dec 2003. Preoperative symptoms and signs and postoperative results were assessed by JOA methods to evaluate the results, both intraoperative and postoperative complications were determined, which included dural tear, never root injury, cage malposition, cage migration, cage subsidence and postolaminectomy adhesive arachnoiditis. All risky factors associated with the complications were analyzed respectively. Results: Intraoperative complications occurred in 16 patients (11. 0%), postoperative complications 28 patients(19. 3%), which including 13 patients(8. 9%) received revision surgery. Within 6 to 44 months (mean 20. 3 months) follow-up, the results was good 72 patients, faire 45, and poor in 28 patients. Conclusion: As a new technique, cage PLIF is difficult technically, the correlation between the potential risks and complications are selections of indications, surgical manipulations, and the designs of the cages.Part II. Revision surgery for failed posterior lumbar interbodyfusion using cagesObjective: To explore the revision surgery and its results forpostoperative complications of cage PILF. Methods: 21 patients of failed cage PLIF were performed revisions from October 1996 to December 2003. The average age was 43. 4years (range from 29 to 58years), and the length of time before revision (implant duration) was 0. 6 year (range, 6days-l. 5years), 16 patients were treated with uninstrumented cage-only fusion. The symptoms and signs included low back pain and radiating pain of legs, which consisted of intermitten claudication and numbness or weekness in legs, dysuria and paralysis in lower limb. X-ray films showed all patients had cage migration and 9 patients had cage subsidence additionally. The operative methods included cage replacement with iliac dowel, deep cage insertion packed with iliac crest bone, and decompression of spinal canal for the symptomatic nerve root. Pedicle screws instruments (12 patients) and intertransverse fusion with autografts and allografts (9 patients) were used subsequently. Results: The mean of follow-up was 14. 2 months (range from 7 to 36 months) after revision. The bony fusion occurred in 13 patients, and the pseudarthrosis existed in 3 patients, which the cages didn' t migrate further during continuous radiography. The clinical symptoms vanished 5 patients, while some symptoms and signs like low back pain, the nerve roots injury, dysuria, and paralysis still exited in some patients within the period of follow-up. Conclusion: The results of revision surgery are not satisfactory according to this study, the revision treatments should be performed as soon as possible if conservative treatment unavailable. We suggest here, correct selections of surgical indications and proper manipulations are the key of prevention of the postoperative complications.Part HI. The anatomic and imaging research for the design ofa PLIF cageObjective: To investigate the effect of the combination of anatomic and imaging measurements for the design of a PLIF cage. Methods: Ten dry lumbarspecimens were chosen to measure the inner, mid, and outer interfacetal distances of inferior facet processes at L3, L4, and L5 with vernier caliper respectively, parasaggital vertebral diameters and pedicles distances were measured as well. 210 normal intervertebral spaces were selected in MRI scans of lumbosacral, the measurements included three interfacetal distances and parasaggital vertebral diameters like above mentioned, anterior, median, posterior heights of intervertbral disc and intervertebral angle at L3/4, L4/5, and L5/S1 levels. The data entered SPSS 10.0 for data processing. Results: Three interfacetal distances were statistically significant...
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