L5 incidence: an important parameter for spinopelvic balance evaluation in high-grade spondylolisthesis

Radiographic Alignment Parameters for Lumbosacral Reconstruction in Patients With Altered S1 Morphology

STUDY DESIGN

Retrospective quantitative analysis study.

OBJECTIVES

Pelvic incidence has been established as central radiographic marker which determines patient-specific correction goals during surgery for adult spinal deformity. In cases with sacral doming or sacral osteotomy where the PI cannot be calculated, reliable radiographic parameters need to be established to determine surgical goals. We aim to determine multiple radiographic parameters and formulas that can be utilized when the S1 superior endplate is obscured.

METHODS

Retrospective analysis was performed on 68 healthy volunteers without prior spine surgery with full-length radiographs. Pelvic incidence, sacral slope, and pelvic tilt were calculated for each patient. Additional measurements such as L4, L5, and S2 incidence, tilt, and slope were collected. A new radiographic parameter defined as the L4-Sciatic notch angle was measured. Regression analysis was performed on each value to determine its relationship with S1 based incidence, tilt, and slope.

RESULTS

Mean values for L5 incidence, L4 incidence, and L4 sciatic notch angle were 21.8° ± 8.9, 4.4° ± 8.1, and 44.4° ± 12, respectively. The linear regression analysis produced the following formulas which can be utilized to determine deformity correction goals when pelvic incidence can be calculated pre-operatively: L5i = .65*S1i-11.4, L4i = .44*S1i-18.6, and L4SNA = -.34*S1i + 66.5. In settings where pelvic incidence cannot be calculated, the following formulas can be utilized: L5i = .66*S2i-32.3 and L4SNA = -.02*S2i2 + 1.1*S2i + 63.5. P-values for all regression analyses were <.001.

CONCLUSION

This study provides target radiographic alignment values that can be utilized for patients with either pre-operative altered S1 endplates or in cases with intraoperative alteration of S1 (sacral osteotomy).

Instrumented L5-S1 interbody graft with IFUSE implant using the reverse Bohlman technique

BACKGROUND

In case of high sacral slope, anterior lumbosacral fusions can be performed by retroperitoneal or transperitoneal approach using a reversed Bohlman technique with an autologous corticocancellous fibular graft. The use of a trans-lumbosacral implant can avoid the iatrogenic effects but currently, there is no implant specifically designed for this fusion technique. Could the IFUSE implant from SI BONE replace a fibular graft to avoiding the iatrogenic effect induced by sampling during a Reverse Bohlman technique?

PATIENTS AND METHODS

We present the case of a 38-year-old woman with L5S1 interbody pseudarthrosis after posterior fixation for grade 2 L5-S1 spondylolisthesis with isthmic lysis of L5, and that of a 69-year-old woman who underwent a posterior T4 fusion to the pelvis for degenerative scoliosis. Both required a trans-lumbosacral instrumented fusion via an anterior approach using the reverse Bohlman technique. Surgical technique was described.

RESULTS

There were no perioperative or postoperative complications. At 6 months, the patients reported a decrease in lumbar and radicular symptomatology. There were no infectious, neurological or vascular complications. CT-scans confirmed the good position and stability of the IFUSE implant.

DISCUSSION

We present an innovative interbody grafting technique adapted to spines with high pelvic incidence. The surgical technique is safe, minimally invasive, and reduces surgical iatrogeny. The short and medium-term results are positive but require longer-term follow-up and a larger cohort.

A Surgical Treatment Algorithm for Restoring Pelvic Balance and Health-related Quality of Life in High-grade Lumbosacral Spondylolisthesis: Prospective Multicenter Cohort of 61 Young Patients

STUDY DESIGN

Retrospective multicenter cohort-study.

OBJECTIVE

We propose an evidence-based surgical algorithm for achieving normal pelvic balance while optimizing health-related quality of life (HRQoL) in high-grade spondylolisthesis.

SUMMARY OF BACKGROUND DATA

The principles of surgical treatment for young patients with high-grade L5-S1 spondylolisthesis remain unclear. There is a growing body of evidence supporting the central role of pelvic balance in the postural control and biomechanics of subjects with high-grade spondylolisthesis.

METHODS

This retrospective study assessed a multicenter cohort of 61 patients with high-grade L5-S1 spondylolisthesis. Classification and regression tree analysis was used to identify objective criteria associated with pelvic balance and HRQoL after surgery.

RESULTS

The most important predictor of a postoperative balanced pelvis was a postoperative L5 incidence ≤63.5 degrees. With postoperative L5 incidence ≤63.5 degrees,a residual slip percentage 9% and performing an L5-S1 posterior lumbar interbody fusion (PLIF)/transforaminal lumbar interbody fusion (TLIF) increased the likelihood of achieving a balanced pelvis postoperatively. When L5 incidence was 63.5 degrees,a balanced pelvis was most likely achieved with fusion limited to L5 proximally, residual slip percentage ≤40%, and residual lumbosacral angle 98 degrees. Predictors of postoperative HRQoL were the preoperative HRQoL score, L5 incidence and slip percentage.

CONCLUSIONS

A surgical algorithm is proposed to achieve normal pelvic balance, while optimizing HRQoL. The first step during surgery is to assess L5 incidence and if L5 incidence is <65 degrees, the next step depends on the pelvic balance. With a preoperative balanced pelvis, it is important not to reduce completely the slip percentage by leaving a slip percentage ≥10%. When the preoperative pelvis is unbalanced, a TLIF/PLIF at L5-S1 is recommended to facilitate correcting the angular deformity at L5-S1. If L5 incidence is ≥65 degrees,a TLIF/PLIF at L5-S1 should be performed to correct the angular deformity at L5-S1, and fusion should ideally end at L5 proximally, in addition to performing gradual reduction of the slip percentage. If fusion up to L4 is required, a lumbosacral angle ≥100 degrees is key.

Management of High-Grade Dysplastic Spondylolisthesis

The Meyerding classification grades the degree of slippage in the sagittal plane on lateral standing neutral imaging: 0% to 25% Grade I, 25% to 50% Grade II, 50% to 75% Grade III, 75% to 100% Grade IV, and greater than 100% Grade V (Spondyloptosis). Grades I and II are considered low-grade and Grades III-V are considered high-grade. There are several etiologies of spondylolisthesis. A classification system of the most common causes: Type I - Dysplastic, Type II - Isthmic (including subtypes: A - Lytic, B - Elongation, and C - Acute fracture), Type III - Degenerative, Type IV - Traumatic, Type V - Pathologic, and Type VI - Iatrogenic. Dysplastic spondylolisthesis is a type of spondylolisthesis that occurs at L5-S1 when dysplastic lumbosacral anatomy is present, and is associated with high-grade slip and spina bifida occulta.

Health-related quality of life and sagittal balance at two to 25 years after posterior transfixation for high-grade dysplastic spondylolisthesis

Aims

High-grade dysplastic spondylolisthesis is a disabling disorder for which many different operative techniques have been described. The aim of this study is to evaluate Scoliosis Research Society 22-item (SRS-22r) scores, global balance, and regional spino-pelvic alignment from two to 25 years after surgery for high-grade dysplastic spondylolisthesis using an all-posterior partial reduction, transfixation technique.

Methods

SRS-22r and full-spine lateral radiographs were collected for the 28 young patients (age 13.4 years (SD 2.6) who underwent surgery for high-grade dysplastic spondylolisthesis in our centre (Scottish National Spinal Deformity Service) between 1995 and 2018. The mean follow-up was nine years (2 to 25), and one patient was lost to follow-up. The standard surgical technique was an all-posterior, partial reduction, and S1 to L5 transfixation screw technique without direct decompression. Parameters for segmental (slip percentage, Dubousset’s lumbosacral angle) and regional alignment (pelvic tilt, sacral slope, L5 incidence, lumbar lordosis, and thoracic kyphosis) and global balance (T1 spino-pelvic inclination) were measured. SRS-22r scores were compared between patients with a balanced and unbalanced pelvis at final follow-up.

Results

SRS-22r domain and total scores improved significantly from preoperative to final follow-up, except for the mental health domain that remained the same. Slip percentage improved from 75% (SD 15) to 48% (SD 19) and lumbosacral angle from 70° (SD 11) to 101° (SD 11). Preoperatively, 35% had global imbalance, and at follow-up all were balanced. Preoperatively, 63% had an unbalanced pelvis, and at final follow-up this was 32%. SRS-22r scores were not different in patients with a balanced or unbalanced pelvis. However, postoperative pelvic imbalance as measured by L5 incidence was associated with lower SRS-22r self-image and total scores (p = 0.029).

Conclusion

In young patients with HGDS, partial reduction and transfixation improves local lumbosacral alignment, restores pelvic, and global balance and provides satisfactory long-term clinical outcomes. Higher SRS-22r self-image and total scores were observed in the patients that had a balanced pelvis (L5I < 60°) at two to 25 years follow-up.

Cite this article: Bone Jt Open 2021;2(3):163–173.

Straighter low lumbar curvature in isthmic spondylolisthesis at L4

BACKGROUND

This study was conducted to compare differences in imaging features and clinical symptoms between patients with single-level isthmic spondylolisthesis (IS) at L4 and at L5 and to investigate the correlation between imaging and clinical parameters.

METHODS

This cross-sectional study evaluated patients with single-level IS who were enrolled between June 2011 and June 2018. A total of 139 patients, 44 in the L4 IS group and 95 in the L5 IS group, met the study criteria and were included. Imaging and clinical parameters obtained from the two groups were compared and analyzed.

RESULTS

Patients in the L4 IS group had smaller lower lumbar lordosis (LLL) (27.1 ± 8.2 vs. 30.9 ± 9.3, P = 0.021) and were of older age (58.5 ± 8.7 vs. 52.8 ± 10.1, P < 0.01) than those in the L5 IS group. As per the Roussouly classification system, most patients with L4 IS were classified as Type 2 (43.2%), whereas most patients with L5 IS fell under Type 3 (44.2%). In the L5 IS group, pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), lumbar lordosis (LL), and L5 incidence (L5I) were positively associated with slippage rate (SR), but the lumbosacral angle (LSA) was negatively associated with SR (P < 0.01). In the L4 IS group, only L5I showed a positive association with SR (P < 0.01). More significant associations were found among sagittal lumbo-pelvic parameters in the L5 IS group, but none were found between SR and Oswestry Disability Index (ODI) in either group.

CONCLUSIONS

When compared with patients with L5 IS, patients with L4 IS were of older age and had straighter low lumbar curvature when they were obviously symptomatic. PI was an important parameter for patients with L5 IS while for those with L4 IS, L5I deserved more attention for its significantly positive correlation with the degree of slippage.

Sagittal reconstruction of lumbosacral contiguous double-level spondylolytic spondylolisthesis: a comparison of double-level and single-level transforaminal lumbar interbody fusion

Background

Contiguous double-level lumbar spondylolytic spondylolisthesis is an extremely rare condition. There is a paucity of data of lumbosacral deformity and sagittal spino-pelvic malalignment among these patients. Moreover, the effect of transforaminal lumbar interbody fusion (TLIF) on sagittal realignment still remains largely unknown. The aim of the study is to investigate the reconstruction of sagittal alignment and the improvement of clinical outcomes after posterior instrumented double-level or single-level TLIF.

Methods

From January 2010 to September 2018, the records of patients with contiguous L4/5 and L5/S1 double-level spondylolytic spondylolisthesis were retrospectively reviewed. Patients who had undergone double-level or single-level TLIF and a minimum of 2 years’ follow-up were included. The slippage parameters and spino-pelvic parameters were measured preoperatively, postoperatively, and at the latest follow-up.

Results

A total of 58 patients (21 males and 37 females, mean age of 57.1 ± 6.9 years) were enrolled. Thirty-eight patients were treated with double-level TLIF and the remaining 20 with single-level TLIF (L4/5 in 14; L5/S1 in 6). After surgery, the spondylolisthesis was significantly reduced at both L4/5 and L5/S1 level (all P < 0.001). There was a significant reduction in pelvic tilt (P < 0.001) and a significant increase in sacral slope (P < 0.001). Significant increase in L4–S1 height (P < 0.001) and L4–S1 lordosis (P = 0.012) and decrease in L5 slope (P = 0.004) and L5 incidence (P = 0.001) were also observed. Compared to single-level TLIF, double-level TLIF increased L4–S1 height (P < 0.001) and L4–S1 lordosis (P < 0.001) and reduced L4-SVA (P = 0.007) and L5 incidence (P = 0.013) more obviously, and the sagittal balance was better corrected in double-level TLIF group (P = 0.006). Double-level TLIF group showed larger increase in VAS scores for low back pain. The incidence of implant-related complications was lower in the double-level group.

Conclusion

Posterior short-segment instrumented TLIF can bring favorable radiographic and clinical outcomes in patients with lumbosacral contiguous double-level spondylolytic spondylolisthesis. Double-level TLIF is more efficient to improve L4–S1 height, regional lumbar lordosis, and global sagittal balance.