Economic implications of dural tears in lumbar microdiscectomies: a retrospective, observational study

STUDY DESIGN

Retrospective cohort study. Level of Evidence Level III. Dural tears (DT) are a frequent complication after lumbar spine surgery. With this study we sought to determine the incidence of DT and the related impact on healthcare expenditures after lumbar discectomies. All patients with first-time single level lumbar discectomies at our institution that underwent minimally-invasive surgery from 2015 to 2019 were reviewed. Age, sex, weight, height, body mass index (BMI), costs, revenues, length of stay (LOS), American Society of Anesthesiology (ASA) score, Charlson Comorbidity Index (CCI) and operation time (OT) were assessed. Exclusion criteria were age < 18 years, previous spine surgery, multiple or traumatic disc herniations but also malignant and infectious diseases. The follow-up time was at least 12 months postoperatively. 358 patients with lumbar discectomies were identified and 230 met the inclusion criteria. The DT incidence was 3.5%. The mean costs (p < 0.001), the loss (p < 0.01) and the operation time (p < 0.0001) were found to be significantly higher in the DT group when compared to the control group of patients without a DT. The revenues were not statistically different between both groups (p > 0.05). Further analysis of the control group by profit and loss revealed significantly higher BMI (p < 0.05), LOS (p < 0.0001) and OT (p < 0.0001) in the loss group. DT represent a significant socioeconomic burden in lumbar spine surgery and cause severe secondary complications. The DT-related impact on healthcare expenses is primarily based on significantly higher OT and a higher mean LOS.

Increased stability due to symmetric cement volume in augmented pedicle screws? A biomechanical study

Pedicle screw instrumentation has become "state of the art" in surgical treatment of many spinal disorders. Loosening of pedicle screws due to poor bone mineral density is a frequent complication in osteoporotic patients. As prevalence of osteoporosis and spinal disorders are increasing with an aging demographic, optimizing the biomechanical properties of pedicle screw constructions and therefore outcome after spinal surgery in osteoporotic patients is a key factor in future surgical therapy. Therefore, this biomechanical study investigated the stability of polymethylmethacrylate (PMMA)-augmented pedicle screw-rod constructions under a deviating distribution of PMMA applied to the instrumentation in osteoporotic human cadaveric vertebrae. We showed that PMMA-augmented pedicle screw-rod constructions tend to be more stable than those with non-augmented pedicle screws. Further, there appears to be a larger risk of screw loosening in unilateral augmented pedicle screws than in non-augmented, therefore a highly asymmetrically distributed PMMA should be avoided.

Severity of spinal degeneration does not affect the pain reduction under continuous epidural analgesia

PURPOSE

To outline clinical effectiveness of continuous epidural analgesia (CEA) in patients with failed back surgery syndrome (FBSS) or lumbar spinal stenosis (LSS) depending on severity of spinal degeneration.

METHODS

In this retrospective cohort study, all patients with FBSS or LSS who underwent CEA within an inpatient rehabilitation program were evaluated. The pain reduction was measured by VAS on an hourly basis. Substantial pain reduction was defined as a minimal clinically important difference (MCID) > 50%. Severity of spinal degeneration, side effects and patient-specific characteristics were documented.

RESULT

We included a total of 148 patients with 105 patients suffering from FBSS and 48 with LSS. The average pain reduction was - 37.6 ± 19.2 in FBSS and - 38.1 ± 17.8 in LSS group (p < .001 and p < .001, respectively). In the FBSS group, sensory deficits (p = .047) and numbness (p = .002), and in the LSS group, a severe disability measured by ODI (38.2 ± 15.4 vs. 57.3 ± 11.3, p < .001) significantly contributed to a worse outcome. The severity of the spinal degeneration and psychological disorders did not affect the pain reduction in terms of MCID.

CONCLUSIONS

This study provides new evidence about CEA in the treatment of FBSS and LSS. CEA provides a significant pain reduction even under intensified physiotherapeutic exercising in patients with severe spinal degeneration and a broad variety of secondary diagnoses. Neurologic deficits in case of FBSS and severe disability in case of LSS may be risk factors for less favorable outcome.

Does index-level pedicle screw instrumentation affect cage subsidence after vertebral body replacement? - A biomechanical study in human cadaveric osteoporotic specimens

BACKGROUND

Vertebral body replacement is a common surgical procedure for treatment of disorders associated with spinal instability. Therefore, pedicle screws are usually inserted in adjacent vertebrae for stabilization of the posterior column, however, there is lack of evidence whether implantation of index-level pedicle screws is beneficial or not. This biomechanical study aims to investigate the effect of pedicle screw instrumentation on axial stability following vertebral body replacement.

METHODS

Unstable fracture at L3 level was simulated in lumbar spines from six human cadaveric specimens. Then instrumentation was performed one level above / one level below index level in three specimens and further, three specimens were instrumented at index-level (L3) additionaly. Then we used a testing protocol for biomechanical evaluation of axial loading on human cadaveric lumbar spines until cage subsidence occurred.

FINDINGS

Our results show that index-level instrumented spines endured significantly higher load until cage subsidence occurred compared to non-index-level instrumented specimens (p = 0.05).

INTERPRETATION

Our results demonstrate pedicle screw instrumentation at index-level vertebra should be considered when possbile as it may have a protective effect against cage subsidence in patients undergoing vertebral body replacement surgery.

Current Evidence on where to End a Fusion within the Thoracolumbar Junction Most Preferably - A Systematic Literature Review

Proximal junctional kyphosis (PJK) is one main complication in the surgical treatment of adult spinal deformities. Ending within the thoracolumbar junction (TLJ) should but cannot always be avoided to reduce the risk for PJK. With this systematic review we sought to define the most preferable vertebra within the TLJ to minimize the risk for PJK and establish recommendations based on our findings. We conducted a systematic literature review by scanning the MEDLINE database in accordance with the PRISMA criteria. All articles addressing primary long-distance dorsal thoracolumbar fusion of at least three segments to treat adult spinal deformities were included. 1385 articles were identified and three were included to this review. The first study showed significantly higher rates of PJK in patients where the construct was extended to T7 or higher when compared to an ending at T11 to L1. The second article stated that an expansion to the TLJ resulted in significantly less surgical revisions due to PJK reduction. On the other hand, the third article found that a fusion of the whole thoracic spine reduces the PJK incidence postoperatively. Even though the most favorable vertebra within the TLJ to avoid PJK best could not yet be determined, our study identifies several principles that represent the current state of evidence for surgical treatment of adult scoliosis. Proper preoperative decision making based on thorough analysis and interpretation of the patient's sagittal alignment parameters can improve the individual outcome critically.

Long-term Radiological and Clinical Outcome after Lumbar Spinal Fusion Surgery in Patients with Degenerative Spondylolisthesis: A Prospective 6-Year Follow-up Study

Objective

To assess which radiological alignment parameters are associated with a satisfactory long‐term clinical outcome after performing lumbar spinal fusion for treating degenerative spondylolisthesis.

Methods

This single‐center prospective study assessed the relation between radiological alignment parameters measured on standing lateral lumbar spine radiographs and the patient‐reported outcome using four different questionnaires (COMI, EQ‐5D, ODI and VAS) as primary outcome measures (level of evidence: II). The following spinopelvic alignment parameters were used: gliding angle, sacral inclination, anterior displacement, sagittal rotation, lumbar lordosis, sacral slope, pelvic tilt and pelvic incidence. Furthermore, the length of stay and perioperative complications were documented. Only cases from 2013 to 2015 of low‐grade degenerative lumbar spondylolisthesis (Meyerding grades I and II) were considered. The patients underwent open posterior lumbar fusion surgery by pedicle screw instrumentation and cage insertion. The operative technique was either a posterior lumbar interbody fusion (PLIF) or a transforaminal lumbar interbody fusion (TLIF) performed by three different senior orthopedic surgeons. Exclusion criteria were spine fractures, minimally invasive techniques, underlying malignant diseases or acute infections, previous or multisegmental spine surgery as well as preoperative neurologic impairment. Of 89 initially contacted patients, 17 patients were included for data analysis (11 males, six females).

Results

The data of 17 patients after mono‐ or bisegmental lumbar fusion surgery to treat low‐grade lumbar spondylolisthesis and with a follow‐up time of least 72 months were analyzed. The mean age was 66.7 ± 11.3 years. In terms of complications two dural tears and one intraoperative bleeding occurred. The average body mass index (BMI) was 27.6 ± 4.4 kg/m² and the average inpatient length of stay was 12.9 ± 3.8 days (range: 8–21). The long‐term clinical outcome correlated significantly with the change of the pelvic tilt (r_s = −0.515, P < 0.05) and the sagittal rotation (r_s = −0.545, P < 0.05). The sacral slope was significantly associated with the sacral inclination (r_s = 0.637, P < 0.01) and the pelvic incidence (r_s = 0.500, P < 0.05). In addition, the pelvic incidence showed a significant correlation with the pelvic tilt (r_s = 0.709, P < 0.01). The change of the different clinical scores over time also correlated significantly between the different questionnaires.

Conclusions

The surgical modification of the pelvic tilt and the sagittal rotation are the two radiological alignment parameters that can most accurately predict the long‐term clinical outcome after lumbar interbody fusion surgery.