The Clinical Application Research Of B-Twin Expandable Spinal Spacer

Objective: To explore the clinical outcome of the expandable spinal spacer(B-Twin) applying in lumbar degenerative disc disease and compare with which using cage. To research the surgical technic and evaluate the preliminary clinical effect of association surgery including B-twin, MED and neotype spine external fixation in the treatment of low-grade lumbar spondylolisthesis.Methods: From June 2004 to December 2006 , 79 patients with lumbar degenerative disc disease, 71 cases operated by microendocopic discectomy,8 cases operated by percutaneous puncture.The study group included 48 males and 31 females ,with average age of 47 years(range,26-63 years)At the same time 112 patients with lumbar degenetative disease underwent PLIF with cage. We randomly selected 30 cases from cage group and 30 cases from B-Twin group. Then the clinical curative effect, the rate of bone graft fusion, the intervertebral space height and complications in two groups were analysed and compared.10 patients with low-grade lumbar spondylolisthesis underwent association surgery including B-twin, MED and neotype spine external fixation. Among them there were 6 men and 4 women, their age ranged from 18 to 68 years, (median 46 years). According to Meyerding typing, 7 cases wereⅠdegree and 3 cases wereⅡdegree which including 3 cases of L4, 7 cases of L5, 3 cases with spondylolysis, 5 cases with spinal stenosis and 2 cases with corresponding intervertebral disk hernia. All of them presented lower back pain, half or both lower extremities pain and anaesthesia, intermittent claudication and so on in diversity degree. The course of disease was from 2 months to 20 years, (median 45 months). Every patient took radiographys on lumbar before operation and then we measured the height of intervertebral space, slippage degree and vertebra stabilization. Results: After surgery the time of follow-up was 12 to 30 months(mean 18 months). 31 cases got bone graft fusion in the period of follow-up.The degree of B-Twin subsided into vertebral body was between 20%-30% in 2 cases,the degree of the others was less than 10%. According to surgery judge criterion of back pain of spinal session of China Othopadics Association , excellent 31 cases,good 8 cases, fair 3cases, poor 1 case,the excellent and good rate was 91%.In these groups, the treatment with B-twin is a minimally invasive technique, it can be completed in diskoscope and is micro-wound, satisfactory in curative effect and the rate of bone graft fusion with fewer complications and sooner recovery, but the cost is more than cage. The treatment of cage essentially is a open sugery for fenestration operation. It has more complications than the former on one hand and it has more sufficient decompression and curative effect with lower cost on the other hand. The rates of bone graft fusion between the two groups are not different in statistics.Surgical operation time of associated B-twin, MED and neotype spine external fixation was 130~260 minutes, (median 160 minutes); Surgical bleed was about 80～300ml, (median 150 minutes); Incision for decompression was just need one stitch and all of them were primary healing. 8 cases were operated on simple segment, while 2 cases were operated on double segments; 4 case were inserted in one B-Twin cage, while 6 cases were inserted in double cages. The length of stay after operation was from 7d to 18d, (median 12d). No complications such as infection, nerves injury and B-Twin displacement were found. 1 patient presented the symptom of nerve root irritation after operation, but had recovered in 2 weeks. Lumbar vertebraes were reposited completely in 9 cases, while in 1 case theⅡdegree lumbar spondylolisthesis changed intoⅠdegree. The lumbar and leg pain of all patients had recovered in diversity degree. According to Nakai grade, in 10 patients, 6 cases were excellent, 3 cases were fine and 1 case was acceptable. All patients were followed up from 6~13months (median 9 months). The radiographys taken in 0。5 year after operation showed that the position of B-twin was well, the height of intervertebral space didn't collapse, no radiolucent zone wasn't found around B-twin and bone graft had fused partly.Conclusion: The B-Twin expansible fusion Cage with small incision, less issue trauma and bleeding can obtain satisfactory operation outcome in the treatment of degeneratibe disc disease. The techniques of B-twin and cage are two treatmens of interbody fusion for lumbar degenetative disease. All of them have advantages and clinical application value. We should choose them to use in clinical application according to clinical specific condition. The association surgery of B-twin, MED and neotype spine external fixation has a micro- surgical trauma, few complications, satisfactory decompression and quick postoperative recovery. The preliminary clinical effect of it in the treatment of low-grade lumbar spondylolisthesis is satisfactory.