Microscopic far lateral transforaminal lumbar/thoracolumbar interbody fusion for patients with kyphotic Kummell's disease - a retrospective comparison study with bone cement enhanced screws plus vertebroplasty.

backgroundVarious surgical techniques for Kummell's disease (KD) have been reported, but the optimal surgical treatment remains controversial.

objectiveWe proposed microscopic far lateral transforaminal lumbar/Thoracolumbar interbody fusion (FL-TLIF) combined with bone cement enhanced screws (BCES) for the treatment of KD with severe kyphotic deformity. We assessed the safety and efficacy of this procedure and compared the clinical and radiological outcomes of this surgical strategy with those of BCES plus vertebroplasty (VP).

methodsThis is a retrospective controlled clinical study. A total of 55 patients with kyphotic KD in our department from July 2016 to August 2022 were included. Twenty-eight were treated with BCES fixation plus vertebroplasty (VP group) while 27 were treated with microscopic FL-TLIF combined with BCES (FL-TLIF group). The demographic data including age, gender, involved segments and bone mineral density (BMD) were collected preoperatively. The intraoperative blood loss, surgical duration, bone cement leakage and adjacent fractures were recorded. The visual analogue scale (VAS), Oswestry Disability Index (ODI), regional Cobb (RC) angle were measured before and after the surgery and in the follow-up periods. The kyphosis correction degree (KCD), correction loss degree (CLD), VAS and ODI improvement were compared between the two groups.

resultsThe mean T-score on dual energy X-ray absorptiometry (DEXA) bone mineral densitometry in the lumbar area is no more than - 2.0, indicating osteopenia or osteoporosis. The minimum follow-up period was 18 months in both groups. The VAS, ODI, and RC angle were significantly improved after surgery in both groups (P < 0.05). The RC angle was maintained at the final follow-up in the FL-TLIF group (P > 0.05), but there was a significant correction loss at the final follow-up in the VP group (P < 0.05). Blood loss and operative time were lower in the VP group compared with the FL-TLIF group (P < 0.05). No significant differences were found between the two groups in terms of VAS and ODI score improvement (P > 0.05). The KCD in the FL-TLIF group was significantly higher than that in the VP group (P < 0.05), while the CLD in the FL-TLIF group was significantly lower than that in the VP group (P < 0.05). Bone cement leakage occurred in 54 screws (20 in FL-TLIF group, 34 in VP group) with no clinical significance. Newly developed vertebral compression fractures adjacent to the level of instrumentation were observed in three patients (10.7%) in the VP group and one case (3.1%) in the FL-TLIF group during the follow-up period. No hardware complications were found in either groups at the last follow-up.

conclusionThe microscopic FL-TLIF combined with BCES fixation is an effective and safe treatment option for KD with severe kyphosis in terms of clinical and radiological outcomes. Compared with BCES plus VP, the microscopic FL-TLIF strategy provided with more kyphosis correction and possibly better correction maintenance tendency at a minor cost of about 40 min additional operation time and 50 ml blood loss.