Outcome of modified posterior lumbar interbody fusion and PMMA augmented pedicle screw instrumentation for lumbar spondylolisis in aged patients

English Keywords:Lumbar spondylolysis  Spinal fusion  Vertebral augmentation  Aged patients  Outcome

English Abstract:

  【Abstract】 Objectives: To evaluate the outcome of modified posterior lumbar interbody fusion(PLIF) and Polymethylmethacrylate(PMMA) augmented pedicle screw instrumentation for lumbar spondylolisis in aged patients. Methods: The clinical outcomes and radiological data were assessed retrospectively in a series of 20 aged patients with lumbar spondylolisis who undergoing surgical treatment from March 2006 to October 2010． The study group consisted of 9 males and 11 females aged 60-79 years（averaging 63.6 years）. 9 cases presented with degenerative spondylolisis, 11 cases with isthmic spondylolisthesis. 4 cases had Ⅰ degree slipping, 12 cases had Ⅱ degree slipping, 4 cases had Ⅲ degree slipping. 14 cases had single-level involved with 3 cases in L3, 2 cases in L4, 9 cases in L5. 6 cases had double-level involved with 4 cases in L4 and L5, 2 cases in L3 and L4. After decompression, the PMMA augmented pedicle screw instrumentation was performed followed by interbody morselized bone graft. The clinical outcomes were determined by Oswestry disabihty index(ODI) and the radiographic evaluation including disc height and foramen height, slipping displacement, slipping degree, and the slipping angle at 3 months after surgery and final follow-up was reviewed. The outcomes of interbody fusion were followed up. Results: Asymptomatic bone cement leakage out of vertebral body was observed in 3 cases. Dural sac laceration occured in 2 cases, with 1 dural sac fissure needing no repair and 1 long laceration being sutured properly． All 2 patients had no cerebrospinal fluid leakage after intervention． 3 cases were complicated with neurological deficit, after the dehydration and nerve nutrient medicine were administered, all neurological deficit recovered completely. All patients had normal sagital plane alignment. The radiological data and ODI between preoperation and 3 months after operation, between preoperation and final follow-up all showed significant difference(P<0.05) respectively, while those between 3 months after operation and fianl follow-up showed no significant difference(P＞0.05). Based on the outcomes of ODI, the rate of excellent-and-good was 89.2％ and 91.3％ for 3 months and final follow-up. No loss of reduction was noted during the mean follow-up of 30.5 months(range, 17-49months). 18 cases were noted bony fusion with the fusion rate of 90％. Conclusions: The modified PLIF and PMMA augmented pedicle screw instrumentation is safe and reliable for lumbar spondylolisis in aged patients.