[Effects of cortical bone trajectory screw in adjacent-segment disease after posterior lumbar interbody fusion].

Objective: To investigate the effect of the cortical bone trajectory (CBT) screw fixation combined with midline lumbar fusion (MIDLF) for adjacent spondylopathy after posterior lumbar interbody fusion. Methods: A retrospective analysis was conducted in 16 patients, including 9 males and 7 females, with a mean age of (68±6) years, who underwent revision surgery for adjacent spondylopathy after posterior lumbar fusion surgery using CBT combined with MIDLF technology in Sir Run Run Shaw Hospital, Zhejiang University from May 2013 to August 2019. The reasons for revision were radiculalgia in 4 cases, intermittent claudication in 10 cases and protrusive dissociate in 2 cases. Eleven cases had 1 segment fused in the first operation, while the other 5 cases received fusion in 2 segments. The average interval time between the first operation and the revision operation was (7.5±2.0) years. For the levels underwent revision, 1 case was L2/3, 6 cases were L3/4, 7 cases were L4/5 and 2 cases were L5/S1. Before the operation, all the patients took X-rays scans of the thoracic and lumbar spine. CT and MRI scans were also performed. The operation time, intraoperative bleeding, surgical complications, visual analog scale (VAS) of low back and leg pain before the operation and at each follow-up were all recorded. Oswestry disability index (ODI) questionnaire was used to evaluate the functional improvement of patients after the operation. Results: All operations were completed successfully. The operation time was 120-240 (170±30) mins, intraoperative bleeding was 100-280 (220±45) ml. One case had a slight split in the isthmus, and the screw was inserted smoothly after adjusting the insertion point. In one case, the cerebrospinal fluid leaked during the operation and was successfully treated with conservative methods including no pillow supine treatment and strengthened anti-infection. The average follow-up time was of (19.5±1.3) months. The VAS of low back pain was 2.9±1.7 before the operation and it was 1.8±0.5 at the last follow-up, and the difference was statistically significant (P<0.01). The VAS of leg pain was 5.9±1.5 before the operation and it was 1.5±0.4 at the last the follow-up (P<0.01). The ODI score was 34.5±3.2 preoperatively and it decreased to 12.6±4.2 at the last follow-up, the difference was statistically significant (P<0.01). Conclusion: CBT technique combined with MIDLF for the adjacent-segment disease after posterior lumbar interbody fusion is minimally invasive and convenient, with good clinical effects. This technique can be used as an option for the revision of adjacent spondylopathy.

[Effects of oblique lateral interbody fusion and transforaminal lumbar interbody fusion for lordosis correction in degenerative lumbar diseases].

Objective: To compare the operation time, estimated blood loss, clinical outcome and correction of lumbar lordosis between oblique lateral interbody fusion (OLIF) and transforaminal lumbar interbody fusion (TLIF) in patients with degenerative lumbar diseases. Methods: Seventy-three patients who underwent OLIF or TLIF surgery from January 2016 to December 2017 in Sir Run Run Shaw Hospital Zhejiang University were analyzed in this retrospective case-control study. The patients included 31 males and 42 females, with a mean age of 65.8 years (range, 36-88 years). Of the patients, there were 9 cases of calcified disc herniation, 34 cases of spinal stenosis, 17 cases of degenerative spondylolithesis, 12 cases of degenerative scoliosis and 1 case of isthmic spondylolithesis. According to the type of surgery, patients were divided into OLIF group (34 cases) and TLIF group (39 cases). The operation time, estimated blood loss and transfusion were recorded, pre-and post-operative visual analogue scale (VAS) for back pain and Oswestry Disability Index (ODI) were evaluated, and pre- and post-operative lumbar lordosis (LL) and fused segment lordosis (FSL) were measured. Student t test were used in comparison between groups. Results: Ten (29.4%) patients in OLIF group and all 39 (100%) patients in TLIF group were supplemented with posterior instrumentation (χ(2)=41.013, P<0.05). The average operation time and estimated blood loss was significantly lower in OLIF group than in those in TLIF group[(163±68) vs (233±79) min, (116±148) vs (434±201) ml, t=4.019, 6.964, both P<0.05]. There was no significant differences in decreases value in VAS and ODI after surgery between the two groups (t=1.716, 0.522, both P>0.05). The correction of LL was 4.0°±10.0° in the OLIF group and 4.2°±6.1° in the TLIF group; the correction of FSL was 4.1°±7.0° in the OLIF group and 5.2°±4.6° in the TLIF group, with no significant differences between the two groups too (t=0.139, 0.805, both P>0.05). The correction of LL was significantly higher in OLIF group with posterior instrumentation than that in TLIF group (9.9°±11.1° vs 4.2°±6.1°, t=2.180, P<0.05). Conclusions: Both OLIF and TLIF can restore LL to some extent, but OLIF has obvious advantages in the operation time and blood loss during surgery. When supplemented with posterior instrumentation, OLIF can achieve better correction of LL than TLIF.