Orthopedics

Feature Article 

Early Clinical Outcome of Lumbar Spinal Fixation With Cortical Bone Trajectory Pedicle Screws in Patients With Osteoporosis With Degenerative Disease

Lei Liu, MD; Shaodong Zhang, PhD; Guozhen Liu, MA; Baolin Yang, MA; Xiaotao Wu, PhD

Abstract

This cohort study aimed to elucidate early surgical outcomes after midline lumbar fusion (MidLIF) with cortical bone trajectory (CBT) screw fixation compared with transforaminal lumbar interbody fusion (TLIF) using traditional pedicle screw (TPS) fixation for lumbar degenerative disease (LDD) in patients with osteoporosis. The authors randomly assigned 70 patients with osteoporosis who had LDD at 1 or 2 adjacent vertebral levels to undergo either MidLIF with CBT (CBT group) or TLIF with TPS fixation (TPS group) from February 2015 to March 2016. Pre- and postoperative lumbar Japanese Orthopaedic Association (JOA) scale scores were assessed and radiographic measurements on dynamic plain radiographs and computed tomography images were analyzed. The final data analysis included 31 patients in the CBT group (mean age, 73.42±6.74 years; t-score, −2.94±0.75) and 32 patients in the TPS group (mean age, 74.84±5.37 years; t-score, −2.92±0.66). Mean JOA score improved significantly in both groups, although no intragroup differences of JOA score improvement were found at the latest follow-up evaluation (P>.05). In addition, significantly higher rates of screw loosening (28.13% vs 6.5%, P=.03) and the amount of subsidence (3.01±0.52 vs 2.49±0.45 mm, P=.02) were found in the TPS group. Rate of radiographic fusion of both groups showed no statistical difference. Both groups of patients achieved a similar rate of radiographic fusion at the 1.5-year follow-up and experienced similar intra- or postoperative complications and postoperative recovery. The MidLIF with CBT screw fixation for short-level lumbar fusion in patients with osteoporosis provided improvement of clinical symptoms comparable to that of TLIF using traditional TPS fixation. In addition, statistically significant lumbar stability was found in the CBT group compared with the TPS group. [Orthopedics. 2019; 42(5):e465–e471.]

Abstract

This cohort study aimed to elucidate early surgical outcomes after midline lumbar fusion (MidLIF) with cortical bone trajectory (CBT) screw fixation compared with transforaminal lumbar interbody fusion (TLIF) using traditional pedicle screw (TPS) fixation for lumbar degenerative disease (LDD) in patients with osteoporosis. The authors randomly assigned 70 patients with osteoporosis who had LDD at 1 or 2 adjacent vertebral levels to undergo either MidLIF with CBT (CBT group) or TLIF with TPS fixation (TPS group) from February 2015 to March 2016. Pre- and postoperative lumbar Japanese Orthopaedic Association (JOA) scale scores were assessed and radiographic measurements on dynamic plain radiographs and computed tomography images were analyzed. The final data analysis included 31 patients in the CBT group (mean age, 73.42±6.74 years; t-score, −2.94±0.75) and 32 patients in the TPS group (mean age, 74.84±5.37 years; t-score, −2.92±0.66). Mean JOA score improved significantly in both groups, although no intragroup differences of JOA score improvement were found at the latest follow-up evaluation (P>.05). In addition, significantly higher rates of screw loosening (28.13% vs 6.5%, P=.03) and the amount of subsidence (3.01±0.52 vs 2.49±0.45 mm, P=.02) were found in the TPS group. Rate of radiographic fusion of both groups showed no statistical difference. Both groups of patients achieved a similar rate of radiographic fusion at the 1.5-year follow-up and experienced similar intra- or postoperative complications and postoperative recovery. The MidLIF with CBT screw fixation for short-level lumbar fusion in patients with osteoporosis provided improvement of clinical symptoms comparable to that of TLIF using traditional TPS fixation. In addition, statistically significant lumbar stability was found in the CBT group compared with the TPS group. [Orthopedics. 2019; 42(5):e465–e471.]

Lumbar degenerative disease (LDD), including degenerative spondylolisthesis, spinal stenosis, and lumbar disk herniation, has been reported at an increased rate in patients with osteoporosis, and the disease requires special consideration for any older patient undergoing spine surgery.1 Little available literature exists specifically evaluating the clinical and radiographic outcomes in patients with osteoporosis undergoing lumbar fixation and interbody fusion. Poor fusion rates may contribute to osteoporosis, and obtaining optimal fixation in the osteoporotic spine is still technically challenging.2 However, the presence of osteoporosis is not a contraindication to surgical intervention for appropriately selected patients; in addition, several new alternative strategies were advocated to improve screw fixation.

The cortical bone trajectory (CBT) screw technique, which moves from inferomedial to superolateral and mostly anchors to a denser cortical layer of the pedicle, differing from the conventional pedicle screw, is reverse designed to increase pullout resistance and to decrease tissue dissection.3 Experimental biomechanical studies have indicated favorable mechanical properties of the CBT screws regarding pullout forces when compared with conventional transpedicular trajectory screws.4,5

Combining the divergent pedicle screws with interbody fusion (midline lumbar fusion [MidLIF]) is considered an alternative method for LDD treatment in patients with osteoporosis.6 However, to the authors' knowledge, no previous study has examined the surgical outcomes, such as pedicle screw loosening, interbody cage subsidence, migration, or iatrogenic fractures, of MidLIF with CBT screw fixation for LDD in patients with osteoporosis in a larger patient population. Therefore, in this current study, the authors sought to elucidate the radiographic and clinical outcomes of MidLIF with CBT screw fixation in patients with osteoporosis at 1.5-years follow-up and to compare these results with those outcomes after transforaminal lumbar interbody fusion (TLIF) using traditional pedicle screw fixation.

Materials and Methods

Patients

The authors conducted an open-label, clinical superiority trial in which patients with osteoporosis who had LDD were randomly assigned to undergo either MidLIF plus CBT screw fixation (CBT group) or TLIF plus traditional pedicle screw (TPS) fixation (TPS group) in a 1:1 ratio. Seventy consecutive patients with osteoporosis with LDD undergoing 1- or 2-level spine surgery from February 2015 to March 2016 were randomly assigned to the CBT or TPS group. Informed consent was obtained from all the patients before enrollment in the study. This study was approved by the institutional ethics committees of the authors' hospital and was conducted in accordance with the ethical guidelines of the Declaration of Helsinki.

Inclusion criteria were diagnosis of LDD according to radiography, computed tomography, and magnetic resonance imaging studies, as well as an additional diagnosis of osteoporosis based on the World Health Organization criteria (t-score, <−2.5). Indications for lumbar surgery were having both clinical symptoms and radiologic evidence of severe 1- or 2-level degenerative lumbar disease. The clinical symptoms and physical examination should be consistent with radiological evidence, and all patients underwent conservative treatment (including bed rest, medical treatment, and rehabilitation therapy) for 6 months with poor response. Exclusion criteria included secondary osteoporosis, history of previous lumbar spinal surgery, other specific spinal conditions (eg, ankylosing spondylitis, cancer, or neurologic disorders), history of vertebral compression fractures in affected segments, or psychological disorders (eg, dementia or drug abuse that caused the surgeon to consider participation to be inappropriate).

Surgical Method

CBT Group. In the CBT group, a mid-line incision was tailored above the affected level using preoperative fluoroscopy. The dorsolumbar fascia was incised bilaterally, preserving the supra- and interspinous ligaments. Exposure and dissection of facet joints should be limited as much as possible to avoid injury of the capsules supradjacent to the fused segment. The lumbar retractors typically used for micro-diskectomy purposes were used. The CBT screw channels were preset and followed a mediolateral- and caudocephalad-directed path, according to the original method under lateral fluoroscopic guidance, with the entry point located at the pars at the junction of the center of the superior articular process and 1 mm inferior to the inferior border of the transverse process. Posterior decompression including laminotomy and partial or total facetectomy was performed uni- or bilaterally in response to pathologic conditions. Interbody fusion was achieved sequentially and followed diskectomy using an interbody device (Capstone Peek; Medtronic Sofamor Danek, Inc, Memphis, Tennessee) filled with local bone graft. Allogeneic bone is considered as a supplemental bone graft when a local laminectomy bone graft was not adequate. The presented channels were verified again with a probe and then the cortical screws, with a 4.5-mm diameter and lengths ranging from 25 to 35 mm, were placed. Wounds were closed in a standard fashion, and drains were placed routinely (Figure 1).

An 84-year-old man with severe intermittent claudication underwent cortical bone trajectory fixation plus midline lumbar fusion. Preoperative plain radiographs indicating reduced disk height of L4/5 and ruling out coronal and sagittal imbalance (a, b). Preoperative computed tomography scan showing L4/5 significant lateral recess stenosis (c). Plain radiographs 3 days postoperatively demonstrating accurate cortical bone trajectory screws implanting and proper location of interbody devices (d, e). Follow-up computed tomography scan obtained 1.5 years postoperatively revealing excellent interbody fusion, without screw loosening and subsidence (f, g).

Figure 1:

An 84-year-old man with severe intermittent claudication underwent cortical bone trajectory fixation plus midline lumbar fusion. Preoperative plain radiographs indicating reduced disk height of L4/5 and ruling out coronal and sagittal imbalance (a, b). Preoperative computed tomography scan showing L4/5 significant lateral recess stenosis (c). Plain radiographs 3 days postoperatively demonstrating accurate cortical bone trajectory screws implanting and proper location of interbody devices (d, e). Follow-up computed tomography scan obtained 1.5 years postoperatively revealing excellent interbody fusion, without screw loosening and subsidence (f, g).

TPS Group. In the TPS group, the mid-line incision was made and the paraspinal muscles were subperiosteally dissected to the tips of the transverse processes. Pedicle screws were placed free-hand using anatomic landmarks, and appropriate placement was confirmed with an intra-operative radiograph. Laminectomy and facetectomy were performed, and the disk was entered on the side of the facetectomy. After thorough disk-space preparation, the bone graft and an interbody cage (Capstone Peek) were placed, the rods were inserted, and compression was performed.

In both groups, all pedicle screws were inserted without an intraoperative navigation system. All patients in both groups wore a lumbosacral orthosis for 3 months postoperatively.

Observation Items

Preoperative clinic charts (including age, sex, body mass index, indication for surgery, workers' compensation, and smoking status) and radiographic imaging (Pfirrmann grading/Modic grading,7 height of affected intervertebral disks, segmental lordosis) were reviewed to extract demographic data, symptoms, and clinical outcomes. Operative reports and inpatient hospital records were reviewed to collect information on the use of image guidance, estimated blood loss, complications, and length of hospital stay. Clinical results of treatment were assessed using the Japanese Orthopaedic Association (JOA) scale scoring system preoperatively and 3 and 18 months postoperatively by independent assessors who were blinded to the type of surgery performed.

Postoperative radiographic imaging was evaluated for evidence of implant subsidence, migration, interbody fusion, iatrogenic fracture, or loosening of posterior pedicle screw fixation. Pedicle screw loosening was validated by a radiographic lucent zone as previously described. Cage subsidence was defined as greater than 2-mm sinking of the cages.8 All patients underwent lateral flexion-extension radiographic evaluation 12 months postoperatively, and successful fusion was defined as the absence of lucency around the graft, evidence of bridging bone between the endplate and the graft, and the absence of movement on dynamic imaging studies. Fusion status was graded as either union in situ (solid fusion without loss of graft height), collapsed union (solid fusion with graft bone collapse or cage subsidence into the adjacent vertebral body), or nonunion, according to the previously reported criteria.9 One blinded independent reviewer (G.L.) evaluated all radiographs to classify subsequent vertebral compression fractures, cage subsidence, pedicle screw loosening, and bone fusion at the 18-month postoperative follow-up for each patient.

Clinic notes were also reviewed to identify any patients who returned to the clinic with complications, which included symptomatic adjacent-segment disease, hemorrhage, hematoma, seroma, infection, neurologic complications, thromboembolic complications (deep venous thrombosis/pulmonary embolus), cardiac complications (including myocardial infarction), urinary and renal complications (including acute renal failure), hardware failure, and pseudarthrosis.

Statistical Analysis

All continuous data are presented as mean±SD, and all categorical data are presented as a percentage or number. The results between groups were compared using the unpaired t test, Mann–Whitney U test, Wilcoxon signed-rank test, Kruskal–Wallis test, and Fisher's exact probability test. Statistical significance was set at P<.05. All statistics were performed using SPSS version 19 software (IBM, Armonk, New York).

Results

Study Population

Between February 2015 and March 2016, after exclusion of otherwise ineligible patients, 70 patients were enrolled and allocated. Thirty-five patients were randomized to each group. Thirty-one patients in the CBT group and 32 in the TPS group were followed successfully. Table 1 presents patients' demographics and treatment, including patient parameters, degenerative grading, surgical level, symptom interval, neurological status, and pain evaluations. The distributions of preoperative patient characteristics were comparable between the groups for the evaluable patients (P>.05).

Demographic and Baseline Characteristics of the 2 Groups

Table 1:

Demographic and Baseline Characteristics of the 2 Groups

Perioperative Clinical Outcomes

The estimated blood loss and length of hospital stay were not significantly different between the CBT and TPS groups (P=.96 and P=.99, respectively), whereas the mean duration of operation was longer (179.68±33.79 vs 143.44±20.69 minutes, P=.00) and radiation exposure was higher (8.03±1.94 vs 5.88±1.56 times, P=.00) in the CBT group than in the TPS group (Table 2). For patients in the CBT group, mean visual analog scores for back and leg pain improved significantly postoperatively (back pain: 7.85±1.82 to 3.25±1.30; leg pain: 8.91±0.92 to 1.85±0.37; both P<.001). Similarly, for patients in the TPS group, mean VAS scores decreased significantly postoperatively (back pain: 7.90±2.01 to 3.45±1.51; leg pain: 8.79±1.22 to 1.87±0.42; both P<.001). Furthermore, no significant differences were found in the VAS leg or back pain scores between the 2 groups at each time point of evaluation, including preoperatively and at postoperative follow-ups (Table 1 and Table 2).

Perioperative Clinical Outcomes of the 2 Groups

Table 2:

Perioperative Clinical Outcomes of the 2 Groups

No statistically significant differences were found between the 2 groups in persistent symptoms, although the rate in the TPS group was 1.57 times higher (40.6% vs 25.8%, P=.16)

Both the CBT and TPS groups had similar improvement in JOA scores postoperatively. The JOA scores of the CBT group improved from 13.50±5.44 preoperatively to 20.37±5.80 postoperatively (P<.001). The JOA scores also improved significantly in the TPS group from 13.57±5.81 preoperatively to 19.86±5.27 postoperatively (P<.001). However, significant intragroup differences of JOA score improvement were found at 18 months of evaluation (P>.05).

Perioperative Radiological Outcomes

Significantly higher rates of screw loosening (28.13% vs 6.5%, P=.03) and amount of subsidence (3.01±0.52 vs 2.49±0.45 mm, P=.02) were found in the TPS group. In addition, no statistically significant differences were found between groups for gross implant migration (9.38% vs 3.2%, P=.32) or radiographic fusion (77.42% vs 58.06%, P=.06) (Table 3). In total, the TPS group had significantly higher radiographic complication rates compared with the CBT group.

Perioperative Radiological Outcomes of the 2 Groups

Table 3:

Perioperative Radiological Outcomes of the 2 Groups

Complications of Surgery

In the CBT group, 1 patient had incidental durotomy during surgery, which was repaired without further complications. One patient in the CBT group underwent secondary surgery due to wound infection. Two patients had asymptomatic screw loosening, as determined by follow-up image evaluations; both patients had minimal symptoms, and the halo signs remained the same without progression or further screw breakage. Thus, none required further surgery (Table 2). In the TPS group, 1 patient had secondary surgery for screw revision due to malpositioning of a L5 pedicle screw. No neurological deficits were observed in any patients who experienced complications.

Discussion

A growing portion of spine patients will have osteopenia or osteoporosis as patients remain active at an older age. Some authors have reviewed the rates of osteopenia and osteoporosis among patients undergoing spine surgery. Chin et al1 reported that, of their spine patients, 46.1% of male patients and 41.4% of female patients had osteopenia and 14% of male patients and 51.3% of female patients had osteoporosis. Surgical complications correlated to osteoporosis include instrument failure (cage migration and screw loosening) and subsequent vertebral compression fractures. Both pedicle screw loosening and cage migration are known to be correlated with an increase in back pain and the rate of nonunion, resulting in poor quality of life.10 In addition to medical treatment of osteoporosis, different surgical techniques have be proposed in patients with osteoporosis undergoing lumbar fusion, including cement augmentation of pedicle screw, expandable pedicle screws, and vertebroplasty in combination with anterior lumbar interbody fusion plus percutaneous posterior fixation, with a satisfactory fusion rate and good stability being reported.11

Among the strategies to improve the pullout strength of pedicle screw fixation in patients with osteoporosis, CBT was proposed and considered a potential option. In contrast to conventional pedicle screw fixation, CBT screws do not penetrate the vertebral body trabecular space. Screws follow a lateral path in the axial plane and a caudocephalad path in the sagittal plane. Several biomechanical and morphometric studies comparing the properties of CBT screw fixation with those of traditional pedicle screws have demonstrated the favorable results of the CBT screw. These studies evaluated either the stability or the fixation strength of cortical screws individually.

Perez-Orribo et al12 found no differences in mean range of motion or lax zone between CBT and traditional pedicle screws during flexion or extension tests on cadaveric lumbar spine, although CBT allowed a greater range of “stiff zone” in axial rotation tests. An in vivo study also compared the long-term stability of CBT and traditional screws and observed that pre- and post-fatigue were statistically equivalent for both CBT and traditional techniques during flexion-extension, lateral bending, and axial rotation flexibility tests, further suggesting that CBT achieves at least comparable stability to traditional pedicle screws.12,13

Fixation strength was also evaluated. Baluch et al14 demonstrated that CBT screws were associated with improved resistance to toggle testing and resistance force compared with traditional trajectory screws in nondestructive flexibility tests on cadaveric lumbar spines. Matsukawa et al15 determined that the insertion torque while placing screws using the CBT technique was 1.71 times higher than that using the traditional technique in in vivo analysis.

Biomechanical and morphometric studies prompted that the CBT pedicle screw technique may be a valuable tool to maximize fixation strength in elderly patients or those with osteoporosis. Regarding clinical outcomes of lumbar fusion with CBT screw fixation focusing on elderly patients or those with osteoporosis, to the authors' knowledge, the current study is the first to investigate the surgical outcomes after MidLIF plus CBT screw fixation for LDD in patients with osteoporosis and to compare these results with those after TLIF with traditional pedicle screw fixation.

Regarding the fact that limiting dissection of the superior facet joints and reducing muscle dissection and retraction with CBT technique, the current authors expected that less exposure in the CBT group would translate into improved peri-operative outcomes. The clinical evidence exhibited a comparable recovery rate of the JOA score at the latest follow-up visit between the CBT and TPS groups. In the CBT group, JOA significantly increased from 13.50 preoperatively to 20.37 postoperatively Consistently, VAS scores significantly decreased in both groups postoperatively. The estimated blood loss and the length of hospital stay were also similar in both groups.

The current authors reviewed relevant studies and found that they reported at least comparable clinical outcomes for CBT pedicle screws. Gonchar et al16 conducted a retrospective comparative study of 100 CBT and 63 traditional pedicle screws in patients with spinal deformity, degenerative disease, osteoporotic vertebral collapse, or trauma. Gonchar et al16 also reported a similar improvement in VAS, Oswestry Disability Index, and Japanese Association Back Pain Evaluation Questionnaire pain scores, similar durations of surgery in the 2 groups (162 vs 177 minutes, respectively), and significantly less blood loss in the CBT group (data not published). Okudaira et al17 retrospectively compared CBT screws and traditional screws in open posterior lumbar interbody fusions for single-level lumbar spondylolisthesis and concluded that CBT screws were associated with shorter duration of surgery (148 vs 184 minutes), less blood loss (132 vs 184 mL), and similar pain and functional outcomes.

In the authors' series, patients in the CBT group had a longer mean duration of operation and more radiation exposure. This may be attributed to the fact that a high-speed burr was used to pre-set screw channels and that imaging guidance is necessary to validate the correct screw implantation, rather than the free-hand technique used when inserting traditional pedicle screws. This also resulted in increased radiation exposure. On the other hand, the learning curve is also a reflecting factor. With the natural learning curve, the current authors observed that operative time decreased as the number of cases performed by the surgeon (S.Z.) increased due to his increasing familiarity with the technique.

For patients with osteoporosis who undergo pedicle screw fixation and interbody fusion, the stability of instrumentation and the rate of union are the biggest concerns. Gonchar et al16 reported frequent screw loosening in the traditional pedicle fixation group (6 vs 1 case), as well as 3 cases of nonunion in the pedicle group and none in the CBT group. Similarly, the current authors' results showed that, compared with traditional pedicle screws, less screw loosening (2 of 31 vs 9 of 32) and a decreased amount of subsidence (2.49±0.45 vs 3.01±0.52) were observed in the CBT group. In addition, although statistically significant differences were achieved, a high rate of union (24 of 31 vs 18 of 32, P=.06) and a fewer number of patients with subsidence (16 of 31 vs 23 of 32, P=.08) were found in the CBT group. Radiological evidence confirmed a good stability and fusion rate when using CBT in patients with osteoporosis.

The current study collected prospective data from a homogeneous population of patients with osteoporosis with degenerative spinal disease and provides promising preliminary results demonstrating the efficacy and safety of CTB screws. However, this study was still constrained by several limitations. First, potential selection bias may undermine the results because randomization was not fully rigorous. Second, the small sample size and short follow-up duration may contribute to a weak statistical power to detect clinical efficacy and complications associated with the CBT technique. Third, heterogeneity among different studies (eg, the current study focused on patients with osteoporosis) limits the ability to obtain directly comparable results from different studies.

Conclusion

The presented data indicated that MidLIF plus CBT screw fixation is an encouraging alternative to TLIF plus traditional transpedicular screws fixation in patients with osteoporosis that provides an enhanced stability of internal fixation and a comparable improvement of clinical symptoms postoperatively. However, limitations due to the technique learning curve, longer duration of operation, and increased radiation exposure should be studied further. More application experience and longer observations of larger groups are needed to further assess the sustainability of the results and validate CBT's advantage in treating LDD in patients with osteoporosis.

References

  1. Chin DK, Park JY, Yoon YS, et al. Prevalence of osteoporosis in patients requiring spine surgery: incidence and significance of osteoporosis in spine disease. Osteoporos Int. 2007;18(9):1219–1224. doi:10.1007/s00198-007-0370-8 [CrossRef]
  2. Liao JC, Chen WJ. Surgical outcomes in the elderly with degenerative spondylolisthesis: comparative study between patients over 80 years of age and under 80 years. A gender-, diagnosis-, and surgical method-matched two-cohort analyses. Spine J. 2018;18(5):734–739. doi:10.1016/j.spinee.2017.08.250 [CrossRef]
  3. Santoni BG, Hynes RA, McGilvray KC, et al. Cortical bone trajectory for lumbar pedicle screws. Spine J. 2009;9(5):366–373. doi:10.1016/j.spinee.2008.07.008 [CrossRef]
  4. Calvert GC, Lawrence BD, Abtahi AM, Bachus KN, Brodke DS. Cortical screws used to rescue failed lumbar pedicle screw construct: a biomechanical analysis. J Neurosurg Spine. 2015;22(2):166–172. doi:10.3171/2014.10.SPINE14371 [CrossRef]
  5. Perez-Orribo L, Kalb S, Reyes PM, Chang SW, Crawford NR. Biomechanics of lumbar cortical screw-rod fixation versus pedicle screw-rod fixation with and without interbody support. Spine (Phila Pa 1976).2013;38(8):635–641. doi:10.1097/BRS.0b013e318279a95e [CrossRef]
  6. Dabbous B, Brown D, Tsitlakidis A, Arzoglou V. Clinical outcomes during the learning curve of MIDline Lumbar Fusion (MIDLF) using the cortical bone trajectory. Acta Neurochir (Wien).2016;158(7):1413–1420. doi:10.1007/s00701-016-2810-8 [CrossRef]
  7. Griffith JF, Wang YX, Antonio GE, et al. Modified Pfirrmann grading system for lumbar intervertebral disc degeneration. Spine (Phila Pa 1976). 2007;32(24):708E–712E. doi:10.1097/BRS.0b013e31815a59a0 [CrossRef]
  8. Ozawa T, Takahashi K, Yamagata M, et al. Insertional torque of the lumbar pedicle screw during surgery. J Orthop Sci. 2005;10(2):133–136. doi:10.1007/s00776-004-0883-3 [CrossRef]
  9. Yamamoto T, Ohkohchi T, Ohwada T, Kotoku H, Harada N. Clinical and radiological results of PLIF for degenerative spondylolisthesis. J Musculoskelet Res. 1998;2(3):181–195. doi:10.1142/S0218957798000184 [CrossRef]
  10. Formby PM, Kang DG, Helgeson MD, Wagner SC. Clinical and radiographic outcomes of transforaminal lumbar interbody fusion in patients with osteoporosis. Global Spine J. 2016;6(7):660–664. doi:10.1055/s-0036-1578804 [CrossRef]
  11. Fischer CR, Hanson G, Eller M, Lehman RA. A systematic review of treatment strategies for degenerative lumbar spine fusion surgery in patients with osteoporosis. Geriatr Orthop Surg Rehabil. 2016;7(4):188–196. doi:10.1177/2151458516669204 [CrossRef]
  12. Perez-Orribo L, Kalb S, Reyes PM, Chang SW, Crawford NR. Biomechanics of lumbar cortical screw-rod fixation versus pedicle screw-rod fixation with and without interbody support. Spine (Phila Pa 1976).2013;38(8):635–641. doi:10.1097/BRS.0b013e318279a95e [CrossRef]
  13. Oshino H, Sakakibara T, Inaba T, Yoshikawa T, Kato T, Kasai Y. A biomechanical comparison between cortical bone trajectory fixation and pedicle screw fixation. J Orthop Surg Res. 2015;10:125. doi:10.1186/s13018-015-0270-0 [CrossRef]
  14. Baluch DA, Patel AA, Lullo B, et al. Effect of physiological loads on cortical and traditional pedicle screw fixation. Spine (Phila Pa 1976).2014;39(22):1297–1302. doi:10.1097/BRS.0000000000000553 [CrossRef]
  15. Matsukawa K, Yato Y, Nemoto O, Imabayashi H, Asazuma T, Nemoto K. Morphometric measurement of cortical bone trajectory for lumbar pedicle screw insertion using computed tomography. J Spinal Disord Tech. 2013;26(6):248E–253E. doi:10.1097/BSD.0b013e318288ac39 [CrossRef]
  16. Gonchar I, Kotani Y, Matsui Y, et al. Experience of 100 consecutive spine reconstructions using cortical bone trajectory (CBT) screws vs traditional pedicle screws. Proceedings of the SMISS Global Forum. , 2014.
  17. Okudaira T, Konishi H, Baba H, et al. Comparison study of lumbar interbody fusion with cortical bone trajectory screws versus conventional open posterior lumbar interbody fusion. Proceedings of the SMISS Global Forum. , 2014.

Demographic and Baseline Characteristics of the 2 Groups

CharacteristicCBT Group (n=31)TPS Group (n=32)P
Age, mean±SD, y73.42±6.7474.84±5.37.36
Sex, female:male, No.25:627:5.48
Body weight, mean±SD, kg68.72±13.9469.65±15.48.79
Symptom duration, mean±SD, mo72.94±68.1964.91±51.60.65
Lumbar spine BMD, mean±SD, t-score−2.94±0.75−2.92±0.66.91
L4 HU, mean±SD88.94±18.6290.06±20.47.85
Smoking, No.811.46
Comorbidity, No.
  Diabetes mellitus1215.51
  Hypertension1716.70
  Other53.47
Primary diagnosis, No..99
  Lumbar disk herniation99
  Lumbar spinal stenosis1314
  Lumbar spondylolisthesis99
Surgical level, No.1.000
  One2728
  Two44
Pfirrmann grade, No..86
  545
  6119
  71013
  865
Preoperative score, mean±SD
  VAS back pain7.85±1.827.90±2.01.91
  VAS leg pain8.91±0.928.79±1.22.74
  JOA13.50±5.4413.57±5.81.85

Perioperative Clinical Outcomes of the 2 Groups

OutcomeCBT Group (n=31)TPS Group (n=32)P
During the procedure
  Operative time, mean±SD, min179.68±33.79143.44±20.69.00
  Estimated blood loss, mean±SD, mL225.16±62.50224.38±61.64.96
  Radiation exposure, mean±SD, No. of times8.03±1.945.88±1.56.00
  Hospital stay, mean±SD, d12.44±2.7212.38±2.80.99
At final follow-up
  JOA score, mean±SD20.37±5.8019.86±5.27.38
  VAS score for back pain, mean±SD3.25±1.303.45±1.511.00
  VAS score for leg pain, mean±SD1.85±0.371.87±0.42.86
  Revision surgery, No.11.75
  Persistent symptoms, No.813.16
  Reporting satisfaction with the surgery, No.2523.53
Complication, No.
  Intraoperative (dural laceration, misplacement)12.51
  Postoperative (symptomatic hematoma, wound infection, symptomatic ASD)35.37

Perioperative Radiological Outcomes of the 2 Groups

OutcomeCBT Group (n=31)TPS Group (n=32)P
Screw loosening, No.29.03
Implant migration, No.13.32
Subsidence, No.1623.08
Amount of subsidence, mean±SD, mm2.49±0.453.01±0.52.02
Radiographic fusion, No.
  Union (in situ or collapsed)2418.06
  Nonunion714
Authors

The authors are from the Department of Spine Center (LL, SZ, GL, BY, XW), the Affiliated ZhongDa Hospital of Southeast University, and the Medical College of Southeast University (GL, BY), Nanjing, JiangSu, China.

The authors have no relevant financial relationships to disclose.

Correspondence should be addressed to: Shaodong Zhang, PhD, Department of Spine Center, the Affiliated ZhongDa Hospital of Southeast University, Dingjiaqiao 87#, Nanjing, 210009, JiangSu, China ( shaodongmd@126.com).

Received: March 14, 2018
Accepted: September 11, 2018
Posted Online: June 13, 2019

10.3928/01477447-20190604-01

Sign up to receive

Journal E-contents