[Biomechanics changes of lumbar spine caused by foraminotomy via percutaneous transforaminal endoscopic lumbar discectomy]

Long-Term Radiographic and Clinical Outcomes in Patients Undergoing Transforaminal Endoscopic Lumbar Discectomy: A Propensity Score Matching Study

Background

Our study aims to investigate the long-term clinical and radiographic effects of transforaminal endoscopic lumbar discectomy (TELD) on lumbar disc herniation.

Patients and Methods

Radiographic and clinical data of patients undergoing TELD in our institution from January 2015 to January 2019 were retrospectively collected. LDH outpatients who had not received surgical treatment during the same period were 1:1 matched by propensity score matching as the conservative group. The radiographic parameters of the two groups at baseline and at the last follow-up (≥24 months) were analyzed.

Results

The study included 47 patients in the TELD group, matched with 47 patients in the conservative group. The disc height of the TELD group at the last follow-up was lower than that at the baseline (P < 0.001), and lower than that of the conservative group at the last follow-up (P < 0.05). The disc degeneration grade of the TELD group at the last follow-up was greater than that at the baseline, and greater than that of the conservative group at the last follow-up. There was no significant difference in the facet joint degeneration in the TELD group between the baseline and the last follow-up, and between the TELD group and the conservative group at the last follow-up (P > 0.05). The pain intensity and disability score in the TELD group at 3-month follow-up and at the last follow-up were significantly lower than those at the baseline (P < 0.001). Six patients in the TELD group required additional surgery during the follow-up period.

Conclusion

Our long-term follow-up data shows that the disc height of the operated level was significantly reduced and the disc degeneration was significantly aggravated in TELD-treated patients; in contrast, the facet joint degeneration did not show significant aggravation.

The biomechanical effect on the adjacent L4/L5 segment of S1 superior facet arthroplasty: a finite element analysis for the male spine

Background

The superior facet arthroplasty is important for intervertebral foramen microscopy. To our knowledge, there is no study about the postoperative biomechanics of adjacent L4/L5 segments after different methods of S1 superior facet arthroplasty. To evaluate the effect of S1 superior facet arthroplasty on lumbar range of motion and disc stress of adjacent segment (L4/L5) under the intervertebral foraminoplasty.

Methods

Eight finite element models (FEMs) of lumbosacral vertebrae (L4/S) had been established and validated. The S1 superior facet arthroplasty was simulated with different methods. Then, the models were imported into Nastran software after optimization; 500 N preload was imposed on the L4 superior endplate, and 10 N⋅m was given to simulate flexion, extension, lateral flexion and rotation. The range of motion (ROM) and intervertebral disc stress of the L4-L5 spine were recorded.

Results

The ROM and disc stress of L4/L5 increased with the increasing of the proportions of S1 superior facet arthroplasty. Compared with the normal model, the ROM of L4/L5 significantly increased in most directions of motion when S1 superior facet formed greater than 3/5 from the ventral to the dorsal or 2/5 from the apex to the base. The disc stress of L4/L5 significantly increased in most directions of motion when S1 superior facet formed greater than 3/5 from the ventral to the dorsal or 1/5 from the apex to the base.

Conclusion

In this study, the ROM and disc stress of L4/L5 were affected by the unilateral S1 superior facet arthroplasty. It is suggested that the forming range from the ventral to the dorsal should be less than 3/5 of the S1 upper facet joint. It is not recommended to form from apex to base.

Level of evidence

Level IV

Risk Factors for Recurrent L5-S1 Disc Herniation After Percutaneous Endoscopic Transforaminal Discectomy: A Retrospective Study

Background

This retrospective study aimed to investigate the risk factors associated with the recurrence of L5–S1 disc herniation after percutaneous endoscopic transforaminal discectomy (PETD).

Material/Methods

There were 484 patients L5–S1 disc herniation who underwent PETD who were divided into the recurrence group (n=46) and the non-recurrence group (n=438). Transforaminal endoscopic approaches included modifications of the Yeung endoscopy spine system (YESS) (the intraforaminal intradiscal approach) and the transforaminal endoscopic spine system (TESSYS) (intraforaminal extradiscal approach). Demographic and clinical characteristics and imaging data were analyzed. The two study groups were compared to determine the factors associated with the recurrence of L5–S1 disc herniation. The patients underwent postoperative follow-up for between one and four years.

Results

At follow-up, 9.504% of patients (46/484) with the recurrence of L5–S1 disc herniation following PETD when compared with the non-recurrence group showed no significant difference for time to return to work, gender, history of diabetes mellitus, trauma, duration of symptoms, smoking and alcohol history, hypertension, location of disc herniation, transverse process length, intervertebral space height, and pelvic incidence angle (P>0.05). However, age, body mass index (BMI), the degree of disc degeneration, sagittal range of motion, lumbar lordosis angle, and sacral slope were significantly associated with the recurrence of L5–S1 disc herniation following PETD (P<0.05). Logistic regression analysis supported these main associations.

Conclusions

The recurrence of L5–S1 disc herniation following PETD was significantly associated with increased age and BMI, more severe disc degeneration, increased sagittal range of motion, increased lumbar lordosis, and sacral slope.