Effect of patient position on the lordosis and scoliosis of patients with degenerative lumbar scoliosis

Sagittal Spinopelvic Alignment in the Standing and Prone Positions of Patients with Old Traumatic Thoracolumbar Kyphosis: Relationship with Immediately Postoperative Parameters

OBJECTIVE

The aim of this study was to investigate the changes in spine-pelvis sagittal parameters from the standing position to the prone position and to study the relationship between sagittal parameters and immediately postoperative parameters.

METHODS

Thirty-six patients with old traumatic spinal fracture combined with kyphosis were enrolled. The preoperative standing position, prone position, and postoperative sagittal parameters of the spine and pelvis, including the local kyphosis Cobb angle (LKCA), thoracic kyphosis angle (TKA), lumbar lordosis angle (LLA), sacral slope (SS), pelvic tilt (PT), pelvic incidence minus lumbar lordosis angle (PI-LLA), and sagittal vertebral axis (SVA), were measured. The data of kyphotic flexibility and correction rate werecollected and analyzed. The parameters of the preoperative standing position, prone position and postoperative sagittal position were analyzed statistically. Correlation analysis and regression analysis of the preoperative standing and prone sagittal parameters and postoperative parameters were conducted.

RESULTS

There were significant differences in the preoperative standing position, prone position, and postoperative LKCA and TK. Correlation analysis showed that preoperative sagittal parameters of the standing position and prone position were all correlated with postoperative homogeneity. Flexibility was not related to the correction rate. Regression analysis showed preoperative standing, prone LKCA, and TK were linear with postoperative standing.

CONCLUSIONS

The LKCA and TK of old traumatic kyphosis obviously changed from the standing position to the prone position, which were linear with postoperative LKCA and TK and can be used to predict postoperative sagittal parameters. This change should be taken into account in the surgical strategy.

Effect of Position on Regional Kyphosis Angle in Patients with Kyphosis Secondary to Symptomatic Old Osteoporotic Thoracolumbar Fracture

OBJECTIVE

The purpose of this study was to evaluate the effect of position on regional kyphosis angle (RKA) in patients with kyphosis secondary to symptomatic old osteoporotic thoracolumbar fracture (so-OTLF).

METHODS

The authors evaluated the radiographic data of patients with kyphosis secondary to so-OTLF who underwent posterior corrective fusion surgery in our hospital. The spine sagittal parameters were evaluated in the standing position preoperatively. RKA was measured under standing radiograph, full-length spine computed tomography image in prone position and intraoperative prone X-ray radiograph, respectively. Changes in RKA were compared between groups.

RESULTS

Thirty-three patients were included. The average RKAs in the standing position, preoperative prone position, and intraoperative prone position were 46.2°, 31.1°, and 30.5° respectively. RKA decreased significantly from standing to preoperative prone position or intraoperative prone position (P < 0.001). In 93.9% (31/33) of the patients, the difference between preoperative prone RKA and intraoperative prone RKA was within 5°. The changes in RKA from standing to intraoperative prone position in the moderate to severe kyphosis group were significantly greater than those in the mild kyphosis group (P < 0.001).

CONCLUSIONS

The reductive effect of the intraoperative prone position was greater in patients with moderate to severe kyphosis deformities. RKA in the preoperative prone position was almost the same as the RKA in the intraoperative prone position. Therefore, assessing preoperative full-length spine computed tomography in the prone position helped formulate the plan for corrective surgery in patients with kyphosis secondary to so-OTLF.

Schober Test and Its Modifications Revisited-What Are We Actually Measuring? Computerized Tomography-Based Analysis

OBJECTIVE

Examine Schober test's (ST), Modified ST (MST), and Modified-Modified ST (MMST) surface markers' accuracy in spanning lumbar L1-S1 motion segments and repeatability related to actual patient anatomy as measured on sagittal CT scans.

METHODS

The study included 25 patients of varying heights, weights, and gender without prior spinal surgery or deformity. Researchers assessed patients' CT scans for ST, MST, and MMST skin levels of the measured cephalic and caudal endpoints.

RESULTS

The original ST failed to include at least one lumbar motion segment in all patients, omitting the L1-L2 motion segment in 17 patients and the L2-L3 in another eight. The additional cephalic length of the MST did not improve the inclusion of the actual L1-S1 components. The MMST measured 19 'patients' entire L1-S1 motion segments, reaching a 76% accuracy rate. WMST, measuring 16 cm (instead of MMST's 15 cm), improved the measurement significantly, measuring the L1-S1 motion segments in all cases (with 100% accuracy).

CONCLUSION

ST and its modifications fail to span the L1-S1 motion segments and are thus prone to underestimating lumbar spine motion. This study shows that the WMST is much more accurate than previous modifications and is a better tool for evaluating lumbar spine motion.

Brace Prescription for Adult Scoliosis - Literature Review

Purpose:

The 2021 SOSORT guidelines stipulated that braces be prescribed for adult scoliosis with chronic pain and progressive curve. Yet, there have been no objective protocols relating to the prescription of the brace. Therefore, this review investigates if there are any objective criteria or generally agreed on protocols for brace prescription in adult scoliosis patients.

Methods:

Relevant papers were searched in PUBMED. Only articles that are in English and cover the clinical aspect of adult scoliosis bracing are included.

Results:

A total of twelve papers were identified. They include different adult scoliosis braces, ranging from elastic belts to rigid braces. The treatment protocol varied tremendously. No objective criteria were found concerning the prescription of a brace, daily wearing time, duration of the intervention, and weaning protocol. The brace treatment was primarily employed to manage low back pain.

Conclusion:

Our search showed no objective criteria and clear indications for bracing and no consensus concerning the prescription of braces, daily wearing time, and duration of the intervention for patients with adult scoliosis.

The authors proposed prescription of a brace be based on more objective radiological criteria and severity of low back pain. Brace prescription should depend on the flexibility of the curve and can range from accommodative to rigid braces of corrective design. “Corrective” brace has to be worn at least 14 hours daily for six months or until the low back pain subsides to the extent that permits daily activities with minimal discomfort. “Accommodative” brace can be worn when required.

Single-position prone transpsoas fusion for the treatment of lumbar adjacent segment disease: early experience of twenty-four cases across three tertiary medical centers

PURPOSE

Prone transpsoas fusion (PTP) is a minimally invasive technique that maximizes the benefit of lateral access interbody surgery and the prone positioning for surgically significant adjacent segment disease. The authors describe the feasibility, reproducibility and radiographic efficacy of PTP when performed for cases of lumbar ASD.

METHODS

Adult patients undergoing PTP for treatment of lumbar ASD at three institutions were retrospectively enrolled. Demographic information was recorded, as was operative data such as adjacent segment levels, operative time, blood loss, laterality of approach, open versus percutaneous pedicle screw instrumentation and need for primary decompression. Radiographic measurements including segmental and global lumbar lordosis, pelvic incidence, pelvic tilt, sacral slope and sagittal vertical axis were recorded both pre- and immediately post-operatively.

RESULTS

Twenty-four patients met criteria for inclusion. Average age was 60.4 ± 10.4 years and average BMI was 31.6 ± 5.0 kg/m². Total operative time was 204.7 ± 83.3 min with blood loss of 187.9 ± 211 mL. Twenty-one patients had pedicle screw instrumentation exchanged percutaneously and 3 patients had open pedicle screw exchange. Two patients suffered pulmonary embolism that was treated medically with no long-term sequelae. One patient had transient lumbar radicular pain and all patients were discharged home with an average length of stay of 3.0 days (range 1-6). Radiographically, global lumbar lordosis improved by an average of 10.3 ± 9.0 degrees, segmental lordosis by 10.1 ± 13.3 degrees and sagittal vertical axis by 3.2 ± 3.2 cm.

CONCLUSION

Single-position prone transpsoas lumbar interbody fusion is a clinically reproducible minimally invasive technique that can effectively treat lumbar adjacent segment disease.

Supervised and unsupervised learning to classify scoliosis and healthy subjects based on non-invasive rasterstereography analysis

The aim of our study was to classify scoliosis compared to to healthy patients using non-invasive surface acquisition via Video-raster-stereography, without prior knowledge of radiographic data. Data acquisitions were made using Rasterstereography; unsupervised learning was adopted for clustering and supervised learning was used for prediction model Support Vector Machine and Deep Network architectures were compared. A M-fold cross validation procedure was performed to evaluate the results. The accuracy and balanced accuracy of the best supervised model were close to 85%. Classification rates by class were measured using the confusion matrix, giving a low percentage of unclassified patients. Rasterstereography has turned out to be a good tool to distinguish subject with scoliosis from healthy patients limiting the exposure to unnecessary radiations.

Body-loop related MRI radiofrequency-induced heating hazards: Observations, characterizations, and recommendations

PURPOSE

To assess RF-induced heating hazards in 1.5T MR systems caused by body-loop postures.

METHODS

Twelve advanced high-resolution anatomically correct human body models with different body-loop postures are created based on poseable human adult male models. Numerical simulations are performed to assess the radiofrequency (RF)-induced heating of these 12 models at 11 landmarks. A customized phantom is developed to validate the numerical simulations and quantitatively analyze factors affecting the RF-induced heating, eg, the contact area, the loop size, and the loading position. The RF-induced heating inside three differently posed phantoms is measured.

RESULTS

The RF-induced heating from the body-loop postures can be up to 11 times higher than that from the original posture. The RF-induced heating increases with increasing body-loop size and decreasing contact area. The magnetic flux increases when the body-loop center and the RF coil isocenter are close to each other, leading to increased RF-induced heating. An air gap created in the body loop or generating a polarized magnetic field parallel to the body loop can reduce the heating by a factor of three at least. Experimental measurements are provided, validating the correctness of the numerical results.

CONCLUSION

Safe patient posture during MR examinations is recommended with the use of insulation materials to prevent loop formation and consequently avoiding high RF-induced heating. If body loops cannot be avoided, the body loop should be placed outside the RF transmitting coil. In addition, linear polarization with magnetic fields parallel to the body loop can be used to circumvent high RF-induced heating.

Disc height discrepancy between supine and standing positions as a screening metric for discogenic back pain in patients with disc degeneration

BACKGROUND CONTEXT

The diagnosis of discogenic low back pain (LBP) from disc degeneration of the lumbar spine is often evaluated with discography. Noninvasive, simple screening methods other than invasive discography are useful, as evidence supporting clinical findings and magnetic resonance imaging (MRI) have come to the forefront.

PURPOSE

To investigate disc height (DH) discrepancy between supine and standing positions on simple radiography to clarify its clinical screening value in individuals with discogenic LBP.

STUDY DESIGN/SETTINGS

Retrospective matched cohort design.

PATIENT SAMPLE

Ninety-two patients with early to middle stage disc degeneration (Pfirrmann grade II, III, or IV).

OUTCOME MEASURES

Each subject underwent simple radiographs and MRI. Baseline characteristics, including demographic data and MRI findings, and radiological findings, including DH discrepancy, segmental angle, and sagittal balance, were analyzed. DH discrepancy ratio was calculated as (1 - [calibrated DH on standing radiography/calibrated DH on supine radiography]) × 100%.

METHODS

We matched LBP group of 46 patients with intractable discogenic pain (≥7 of visual analog scale scores) confirmed by discography with control group of 46 patients with similar stage disc degeneration with mild LBP (≤4 of visual analog scale scores). Binary regression analysis, receiver operating characteristic curve analysis, and cut-off value for diagnosis were used to evaluate and clarify diagnostic value of various factors.

RESULTS

There was no significant difference between the two groups in terms of baseline characteristics, including age, sex, body mass index, pathological level, and magnetic resonance findings such as disc degeneration, high intensity zone, and para-spinal muscle volume. Among the various radiological findings, the calibrated mean DH in the standing position (20.87±5.65 [LBP group] vs. 26.95±3.02 [control group], p<.001) and the DH discrepancy ratio (14.55±6.13% [LBP group] vs. 1.47±0.75% [control group], p=.007) were significantly different between the two groups. The cut-off value for DH discrepancy ratio to screen discogenic LBP was ≥6.04%. Additionally, as a compensation for pain, sagittal vertical axis (3.43±2.03 cm [LBP group] vs. -0.54±3.05 cm [control group], p=.002) and pelvic incidence (54.74±6.76° [LBP group] vs. 43.98±8.67° [control group]; p=.006) were different between the two groups.

CONCLUSIONS

The results suggest that DH discrepancy between the supine and standing positions could be a screening metric for discogenic LBP in early to middle stage disc degeneration of the lumbar spine.

A novel system for accurate lumbar spine pedicle screw placement based on three-dimensional computed tomography reconstruction

Objectives

The accuracy of pedicle screw placement strongly affects the outcome of spinal surgery and has mainly relied on the surgeons’ experience. There is no simple, low-cost, and effective pedicle screw placement system to assist new spinal surgeons with less experience.

Methods

We designed a localization system with six parameters (starting point height [SP-H], starting point length [SP-L], transverse section angle, sagittal section angle [SSA], pedicle width [W] and height [H]) based on preoperative computed tomography reconstruction and combined it with the Roussouly classification to guide lumbar spine pedicle screw placement and analysed the change patterns of the six parameters in 50 participants.

Results

Based on the system, we confirmed that combining SP-H and SP-L can localize the entrance of the pedicle screw. Furthermore, we considered that SP-L and transverse section angle would be a new standard for determination of the transverse orientation of the pedicle screw. More importantly, the linear regression equations between H and W and SP-H and H were concealed. In addition, H and W can guide the appropriate selection of pedicle screw. Moreover, change patterns of SSA combined with the Roussouly classification indicate that SSA of L3 can be used as a benchmark to guide the establishment of sagittal alignment of the lumbar spine.

Conclusions

Understanding and applying the six-parameter localization system are essential for achieving accuracy in lumbar spine pedicle screw placement, and the system is a useful guide in the establishment of sagittal alignment.

The translational potential of this article

This study provides a new pedicle-screw placement system for accurate lumbar spine pedicle screw placement based on three-dimensional CT reconstruction, requiring six parameters to guide the system.

Effect of position on lumbar lordosis in patients with adult spinal deformity

OBJECTIVE

The purpose of this study was to evaluate the effect of position on lumbar lordosis (LL) in adult spinal deformity (ASD) patients.

METHODS

The authors evaluated the radiographic data of ASD patients who underwent posterior corrective fusion surgery from the thoracic spine to L5, S1, or the ilium for the treatment of ASD of the lumbar spine. The spinopelvic parameters were measured in the standing position preoperatively. LL was also evaluated in the supine position preoperatively and in the prone position on the surgical frame. Changes in LL were compared between groups.

RESULTS

Eighty-five patients were included. The average LL in standing, supine, and prone positions was 11.8°, 24.3°, and 24.0°, respectively. LL increased significantly from standing to supine or prone position (p < 0.001). In 80 patients (94.1%), the difference between supine LL and prone LL was within 5°. Change in LL from standing to prone position was significantly higher in the severe deformity group.

CONCLUSIONS

The lordotic effect of intraoperative prone positioning was remarkable in patients with severe deformities. LL in the supine position was approximately the same as that in the prone position. Therefore, assessing preoperative supine lateral lumbar radiographs enables one to plan corrective spinal surgeries in ASD patients.