Clinical Study On Oblique Lumbar Interbody Fusion For Lumbar Degenerative Diseases

Objectives:To investigate the learning curve,clinical outcomes and complications of oblique lumbar interbody fusion(OLIF)for lumbar degenerative lumbar diseases,our purpose is to increase experiences on minimally invasive lumbar fusion for lumbar degenerative diseases.Methods:From November 2014 to february 2017,OLIF were performed in 86 patients with lumbar degenerative diseases.All of the patients with intact clinical data were analyzed.The study was divided into three parts.Part 1:Learning curve of OLIF.A prospective analysis of 49 consecutive patients that underwent a single-level OLIF was performed.Only those patients that were single level,index surgeries were included.Every patient had a diagnosis of degenerative lumbar diseases including lumbar spondylolisthesis(25 cases),discogenic low back pain(14 cases)or segmental instability(10 cases).Patients underwent an indirect decompression and fusion using an expandable tubular retractor and single intervertebral cage with bilateral percutaneous pedicle screw fixation.49 patients were divided into the early group(the first 24 patients)and the latter group(25 patients after the initial 24 patients).The following data were compared between the two groups: surgical time for(Skin-Skin,minutes),estimated blood loss(ml),X-ray exposure time(seconds),the clinical and radiographic results,and intra-/postoperative complications.All intraoperative parameters only included the measurement and findings related with the OLIF procedure.The learning curve was assessed using a logarithmic curve-fit regression analysis.Part 2:Early outcomes and complications of OLIF.A retrospective analysis of 86 consecutive patients that underwent a OLIF was performed.Every patient had a diagnosis of degenerative lumbar diseases including lumbar spondylolisthesis(41 cases),lumbar instability(14 cases),discogenic low back pain(14 cases),adjacent segmental disease after posterior lumbar fusion(10 cases)or adult lumbar scoliosis(7 cases).Sixty-one patients underwent OLIF with bilateral percutaneous pedicle screw fixation.Twenty-five received stand alone OLIF.Single-level OLIF was performed in 79 cases.Multilevel OLIF was performed in 7 patients with adult lumbar scoliosis,including two-level OLIF in 5 cases,three-level OLIF in 2 cases.All intraoperative parameters such as surgical time and estimated blood loss,and intra-/postoperative complications only included the measurement and findings related with the OLIF procedure.The early clinical results and complications were assessed and analyzed on the basis of follow-up clinical data.The influences of vertebral osteoporosis on endplate fractures and cage subsidence,and the effect of stand-alone OLIF or combined with percutaneous pedicle screw fixation on cage subsidence and interbody fusion were analyzed,respectively.Results:Part 1:Average operative time was significantly longer in the early group(47.1±10.6 min)compared with the latter group(37.2±10.0 min)(P=0.002).In comparison with the latter group,the early group had significantly more X-ray exposure time(25.3±6.1 sec versus 17.1±6.9 sec,P<0.000).The operative and X-ray exposure time gradually decreased as the series progressed,and an asymptote was reached after about 20 cases.There was no statistically significant difference in intraoperative blood loss between the early group(28.1±18.2 ml)and the latter group(24.4±10.9 ml)(P=0.642).The most observed complications were donor site pain(11 cases,45.8%),followed by thigh numbness/pain(5 cases,20.8%)and psoas/quadriceps weakness(2cases,8.3%),paralytic ileus(one case,4.2%)and sympathetic nerve injury(one case,4.2%)in the early group.Donor site pain occurred in four patients(16.0%),thigh numbness/pain in three patients(12.0%),psoas/quadriceps weakness in one patient(4.0%)and sympathetic nerve injury in one patient(4.0%)in the latter group.All complications were transient and resolved within 3 months.The incidence of complications excluding donor site pain in the early period(early group)and the later period(latter group)was 37.5% and 20.0%,respectively,showing temporal improvement after the introduction,although there were no significant differences in perioperative complications between both groups(P=0.175).Forty-nine patients were followed up for more than 1 year,and the average follow-up period was 18.5±3.9 months.The clinical outcomes were basically identical in the two group based on the back pain VAS and ODI scores.Radiographic evaluation showed similar bony fusion in the early group(22 of 25 cases)with the latter group(22 of 24 cases)in last follow-up.Part 2:Mean operative time was 41.7±11.3 min.Average blood loss was 20.5±14.3 ml.The complications were donor site pain(17 cases,19.8%),followed by thigh numbness/pain(11 cases,12.8%),end-plate fracture(10 cases,11.6%),psoas/quadriceps weakness(4 cases,4.7%),sympathetic nerve injury(two cases,2.3%),paralytic ileus(one case,1.2%)and intervertebral infection(one case,1.2%).No permanent neurological sequelae were observed in our series.Eighty-six patients were followed up for more than 1 six months,and the average follow-up period was 13.4±4.8 months.The back pain VAS and ODI scores decreased respectively from 6.1±2.5 before surgery to 1.3±0.8 in final follow-up(P=0.003)and from 32.6±10.1 before surgery to 14.2±4.5 in last follow-up(P=0.004).Total fusion rate was 91.9%(79/86 cases)in final follow-up.Severe vertebral osteoporosis increased significantly vertebral fractures during OLIF procedure(P=0.003),while compared with no or osteoporosis.Osteoporosis increased significantly cage subsidence in last follow-up while in comparison to no osteoporosis(P=0.000).Stand-alone OLIF or combined with percutaneous pedicle screw fixation had no significant effect on cage subsidence and interbody fusion(P=0.199).Conclusions:1.OLIF is a relatively novel lumbar fusion technique and present a learning curve similar to other minimally invasive spinal surgeries.2.OLIF provide a good short term clinical outcomes for selected lumbar degenerative diseases.It is stressed that close attention to detail during procedure should been payed to complications related with OLIF and prevention of the complications.