[Dorsal lumbar interbody implantation of cages for stabilizing segmental spinal instabilities]

Clinical, Functional, and Radiologic Outcome of Single- and Double-Level Transforaminal Lumbar Interbody Fusion in Patients with Low-Grade Spondylolisthesis

Objective:

The main objective is to determine the functional, clinical, and radiological outcome of patients with low-grade spondylolisthesis undergoing single- or double-level transforaminal lumbar interbody fusion (TLIF).

Materials and Methods:

This quasi-interventional study was conducted during a 2-year period from 2016 to 2018 in Shiraz, Southern Iran. We included all the adult (≥18 years) patients with low-grade spondylolisthesis (Meyerding Grade I and II) who underwent single- or double-level TLIF in our center. The spinopelvic parameters including pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), lumbar lordosis (LL), and segmental LL (SLL) were measured. The pain intensity and disability were measured utilizing the visual analog scale (VAS) for back and leg pain and Oswestry Disability Index (ODI), respectively, after 1 year.

Results:

Overall, we included a total number of 50 patients with mean age of 54.1 ± 10.48 years. After the surgery, the PI (P = 0.432), PT (P = 0.782), and SS (P = 0.466) were not found to be statistically changed from the baseline. However, we found that single- or double-level TLIF was associated with increased LL (P < 0.001) and SLL (P < 0.001). Regarding the clinical outcome measures, both back (P = 0.001) and leg (P < 0.001) VAS improved after the surgery significantly. In addition, we found that improved leg VAS was positively correlated with improved ODI (r = 0. 634; P < 0.001).

Conclusion:

Single- or double-level TLIF is associated with increased global and SLL along with improved leg and back pain and disability in patients with low-grade spondylolisthesis. Interestingly, improved leg pain is correlated to improved disability in these patients.

RADIOGRAPHIC RESTORATION OF LUMBAR ALIGNMENT AFTER TRANSFORAMINAL LUMBAR INTERBODY FUSION

OBJECTIVE

Restoration of lumbar lordosis is a critical factor in long-term success after lumbar fusions. Transforaminal lumbar interbody fusion (TLIF) is a popular surgical technique in the lumbar spine, but few data exist on change in spinal alignment after the procedure.

METHODS

Eighty patients who underwent TLIF surgery were retrospectively reviewed (minimum follow-up period, 2 years). Standing x-rays were assessed for changes in focal and segmental kyphosis, and restoration of lumbar lordosis. Improvement in spondylolisthesis, sagittal balance, and scoliosis were also assessed. Fusion was assessed as well.

RESULTS

Eighty operations were performed at 107 levels. Mean presenting lumbar Cobb angle measurement (L1–S1) was 36.3 ± 4.5 degrees (range, 12–77 degrees). Forty patients (50%) had sagittal imbalance. Mean postoperative Cobb angle (L1–S1) was 55.1 ± 6.6. Thirty-three of 36 patients with segmental kyphosis (92%) had restoration of lordosis. Improvement in alignment was most prominent at the surgical level (mean increase in lordosis, 20.2 ± 4.2 degrees). The improvement in lumbar lordosis among patients undergoing multilevel TLIFs (27.3 ± 3.4 degrees) was significantly higher compared with patients undergoing single-level operations (17.4 ± 4.4) (Student's t test, P = 0.0004). Thirty of the 40 patients with sagittal imbalance (75%) achieved immediate restoration of normal sagittal balance. The ability to restore normal sagittal balance was correlated with a sagittal imbalance of less than 10 cm (P = 0.0001). Spondylolisthesis was completely corrected at the TLIF site in 90 of 99 levels (91%). Three patients (4%) required reoperation, 2 for implant disengagement and 1 for worsening kyphoscoliosis above the original surgical levels. Two of the 80 patients had pseudoarthrosis; hence, the rate of pseudoarthrosis was 2.5%.

CONCLUSION

The TLIF operation is highly effective in improving spinal alignment in patients with degenerative spinal disorders when the appropriate surgical technique is implemented.

Interkorporelle Metallimplantate („Cages“) bei lumbalen Spondylodesen

Over the last 15 years, interbody metal implants have become commonly used worldwide for lumbar interbody fusion. The so called "cages" are made of metal or absorbable materials. By using different surgical techniques, they can be implanted either regularly or via endoscopy. The published results on surgical techniques using cages for the lumbar spine show, in most cases and with or without additional instrumentation, rates of fusion of more than 90%. It seems that the use of osteoinductive substances (especially BMP) leads to even better results. Dorsoventral fusion with internal fixation and bone show the same rate of consolidation, but the advantages of cages are primarily in the maintenance of the distraction and the possibility of a single surgical procedure without additional instrumentation (including endoscopy), and in a lower donor side morbidity.

Radiographic characteristics on conventional radiographs after posterior lumbar interbody fusion: comparative study between radiotranslucent and radiopaque cages

The problem of determining solidity of a fused spinal segment still remains. Our purpose is to evaluate radiographic findings after posterior lumbar interbody fusion (PLIF) with cages and estimate their relative value in judging fusion status. Radiographic follow-up was performed in patients after PLIF with cages of either radiotranslucent or radiopaque material. Conventional radiographs were obtained 6 weeks, 3 and 6 months, and then yearly after surgery for spinal instability for 64 patients. We differentiated between uncertain (increased density within the cage, increase of sclerotic endplates, and posterolateral fusion) and definite (trabecular continuous bone bridging within the implant and periimplant new bone formation with bridging of the intervertebral space) fusion signs. A fusion rate of 51.5% after 12 months, 61.4% after 24 months, 66.7% after 36 months, and 77.8% after 48 months postoperatively was found. We found only a slight, nonsignificant correlation between radiographic fusion and patient-assessed clinical outcome. There is evidence that radiographic fusion criteria occur in a specific chronologic order. The interpretation of fusion status is notably impaired by the use of radiopaque cages. Criteria to standardize the interpretation and evaluation of radiographic findings after PLIF are discussed.

Radiographic spinal profile changes induced by cage design after posterior lumbar interbody fusion preliminary report of a study with wedged implants

STUDY DESIGN

A prospective comparative radiographic study between two geometrically varying implants utilized in single-level posterior lumbar interbody fusion (PLIF) was performed.

OBJECTIVE

The aim of this study was to determine the influence of 4 degrees wedged cages on postoperative lateral lumbar spinal profile.

SUMMARY OF BACKGROUND DATA

The biomechanical and clinical importance of realigning the sagittal lumbar profile in surgical management of spinal instabilities is known. Wedged cages are therefore increasingly attaining popularity in PLIF. As yet the significance of wedged implants on postoperative sagittal spinal profile has not been assessed.

METHODS

Forty patients were randomly assigned to two equal-sized groups. In one group rectangular cages and in the second group cages with a wedged design and an inclination of 4 degrees were implanted. Quantitative assessment of the lumbar spinal profile on standing neutral lateral radiographs was performed before surgery as well as 6 weeks and 12 months after surgery. Results were statistically compared.

RESULTS

A significant improvement of lumbar sagittal profile after use of 4 degrees wedged compared with nonwedged cages was not found. The greatest effect on lumbar profile and segmental lordosis was observed in fusion of segment L4-L5 with 4 degrees wedged cages.

CONCLUSIONS

These results show that normal sagittal alignment after single-level lumbar fusion can be achieved with rectangular and 4 degrees wedged cages. Although results after utilization of 4 degrees wedged cages do not significantly differ, these implants offer the surgeon one more sizing variation with which physiologic lumbar lordosis may be attained. The biomechanical implications of wedged implants on the rigidity of a fused segment remain to be analyzed.