Thoracic Spinal Stability and Motion Behavior Are Affected by the Length of Posterior Instrumentation After Vertebral Body Replacement, but Not by the Surgical Approach Type: An in vitro Study With Entire Rib Cage Specimens.

Spinal tumors and unstable vertebral body fractures usually require surgical treatment including vertebral body replacement. Regarding primary stability, however, the best possible treatment depends on the spinal region. The purpose of this in vitro study was to evaluate the effects of instrumentation length and approach size on thoracic spinal stability including the entire rib cage. Six fresh frozen human thoracic spine specimens with intact rib cages (C7-L1) were loaded with pure moments of 5 Nm in flexion/extension, lateral bending, and axial rotation, while monitoring the relative motions of all spinal segments using optical motion tracking. The specimens were tested (1) in the intact condition, followed by testing after vertebral body replacement at T6 level using a unilateral approach combined with (2) long instrumentation (T4-T8) and (3) short instrumentation (T5-T7) as well as a bilateral approach combined with (4) long and (5) short instrumentation. Significant increases of the range of motion (p < 0.05) were found in the entire thoracic spine (T1-T12) using the bilateral approach and short instrumentation in primary flexion/extension and in secondary axial rotation during primary lateral bending compared to both conditions with long instrumentation, as well as in secondary lateral bending during primary axial rotation compared to unilateral approach and long instrumentation. Compared to the intact condition, the range of motion was significantly decreased using unilateral approach and long instrumentation in flexion extension and secondary lateral bending during primary axial rotation, as well as using bilateral approach and long instrumentation in lateral bending. On the segmental level, the range of motion was significantly increased at T4-T5 level in lateral bending using unilateral approach and short instrumentation and significantly decreased using bilateral approach and long instrumentation compared to their respective previous conditions. Regardless of the approach type, which did not affect thoracic spinal stability in the present study, short instrumentation overall shows sufficient primary stability in the mid-thoracic spine with intact rib cage, while creating considerably more instability compared to long instrumentation, potentially being of importance regarding long-term implant failure. Moreover, short instrumentation could affect adjacent segment disease due to increased motion at the upper segmental level.

In vitro comparison of personalized 3D printed versus standard expandable titanium vertebral body replacement implants in the mid-thoracic spine using entire rib cage specimens.

BACKGROUND: Expandable titanium implants have proven their suitability as vertebral body replacement device in several clinical and biomechanical studies. Potential stabilizing features of personalized 3D printed titanium devices, however, have never been explored. This in vitro study aimed to prove their equivalence regarding primary stability and three-dimensional motion behavior in the mid-thoracic spine including the entire rib cage. METHODS: Six fresh frozen human thoracic spine specimens with intact rib cages were loaded with pure moments of 5 Nm while performing optical motion tracking of all vertebrae. Following testing in intact condition (1), the specimens were tested after inserting personalized 3D printed titanium vertebral body replacement implants (2) and the two standard expandable titanium implants Obelisc™ (3) and Synex™ (4), each at T6 level combined with posterior pedicle screw-rod fixation from T4 to T8. FINDINGS: No significant differences (P < .05) in primary and secondary T1-T12 ranges of motion were found between the three implant types. Compared to the intact condition, slight decreases of the range of motion were found, which were significant for Synex™ in primary flexion/extension (-17%), specifically at T3-T4 level (-46%), primary lateral bending (-18%), and secondary lateral bending during primary axial rotation (-53%). Range of motion solely increased at T8-T9 level, while being significant only for Obelisc™ (+35%). INTERPRETATION: Personalized 3D printed vertebral body replacement implants provide a promising alternative to standard expandable devices regarding primary stability and three-dimensional motion behavior in the mid-thoracic spine due to the stabilizing effect of the rib cage.

Routine Cerebrospinal Fluid (CSF) Parameters in Patients With Spinal Muscular Atrophy (SMA) Treated With Nusinersen.

Background: Nusinersen is an antisense-oligonucleotide (ASO) approved for treatment of 5q-spinal muscular atrophy (SMA). Since the drug cannot cross the blood-brain barrier (BBB), it must be administered into the cerebrospinal fluid (CSF) space repeatedly by lumbar puncture. However, little is known whether ASOs have an impact on CSF routine parameters that may yield information on CSF flow and/or intrathecal inflammation. The objective of this study was to examine CSF routine parameters in SMA patients treated with nusinersen. Methods: Routine CSF parameters [white cell count, total protein, CSF/serum quotients of albumin (Qalb), lactate, and oligoclonal IgG bands (OCB)] of 60 SMA patients (type 1, 2, and 3, aged 7-60 years) were retrospectively analyzed. Results: White cells ranged from 0 to 4/µL in CSF; a singular case of pleocytosis (8/µL) was observed in a patient in parallel with a systemic infection. Total protein and Qalb showed a mild increase from baseline to the following lumbar punctures (except for total protein in CSF at the fourth injection of nusinersen). Lactate levels revealed a stable course. In one patient, positive OCB in CSF were transiently observed. The slight change in total CSF protein and Qalb may be caused by repeated lumbar puncture and/or intrathecal administration of the drug. Conclusion: Our data suggest that a regular examination of routine CSF parameters in patients in which intrathecal ASOs are administered is important to obtain information on possible side effects and to gain further insights into intrathecal processes.

Evaluation criteria for the assessment of occupational diseases of the lumbar spine - how reliable are they?

BACKGROUND: In 2005, the German Association of Occupational Accident Insurance Funds (DGUV) defined radiological evaluation criteria for the assessment of degenerative occupational diseases of the lumbar spine. These include the measurement of intervertebral osteochondrosis and classification of vertebral osteosclerosis, antero-lateral and posterior spondylosis, and spondyloarthritis via plain radiography. The measures currently remain in daily use for determining worker compensation among those with occupational diseases. Here, we aimed to evaluate the inter- and intra-observer reliability of these evaluation criteria. METHODS: We enrolled 100 patients with occupational degenerative diseases of the lumbar spine. Native antero-posterior and lateral radiographs of these patients were evaluated according to DGUV recommendations by 4 observers with different levels of clinical training. Evaluations were again conducted after 2 months to assess the intra-observer reliability. RESULTS: The measurement of intervertebral osteochondrosis showed good inter-observer reliability (ICC: 0.755) and excellent intra-observer reliability (ICC: 0.827). The classification of vertebral osteosclerosis exhibited moderate kappa values for inter-observer reliability (К: 0.426) and intra-observer reliability (К: 0.441); the remaining 3 criteria showed poor inter- and intra-observer reliabilities. CONCLUSION: The measurement of intervertebral osteochondrosis and classification of vertebral osteosclerosis showed adequate inter- and intra-observer reliability in the assessment of occupational diseases of the lumbar spine, whereas the classification of antero-lateral and posterior spondylosis and spondyloarthritis stage exhibited insufficient reliability. Hence, we recommend the revision of the DGUV recommendations for the evaluation of occupational diseases of the lumbar spine.

Neurochemical markers in CSF of adolescent and adult SMA patients undergoing nusinersen treatment.

BACKGROUND: There is limited information on neurochemical markers being used to support and monitor the affection of motoneurons in patients with spinal muscular atrophy (SMA). The objective of this study was to examine neurochemical markers in cerebrospinal fluid (CSF) under treatment with the antisense-oligonucleotide (ASO), nusinersen. METHODS: We measured markers of axonal degeneration [neurofilament light chain (NfL) and phosphorylated neurofilament heavy chain (pNfH)] along with basic CSF parameters in 25 adolescent and adult SMA type 2 and 3 patients at baseline and after four intrathecal injections of nusinersen. Neurochemical markers were compared with controls. In addition, neurochemical markers in SMA patients were related to the Hammersmith Functional Rating Scale Expanded (HFMSE). RESULTS: No significant difference in neurofilament (Nf) values was observed between SMA and control group, neither at baseline nor after four injections of nusinersen. NfL, protein and quotients of albumin (Qalb) increased slightly in SMA patients after the fourth injection. The slight increase of NfL could be related to the development of mild CSF flow change. No relations were observed between changes in Nf and HFMSE. CONCLUSION: We assume that Nf levels in CSF in these patients may result from slow disease progression in this stage of disease, pre-existing loss of motoneurons due to long disease duration besides affection of the LMN only. Therefore, we conclude that Nf levels in CSF do not seem useful as diagnostic and monitoring markers in adolescent and adult SMA type 2 and 3 patients.

Intrathecal administration of nusinersen in adolescent and adult SMA type 2 and 3 patients.

Spinal muscular atrophy is a genetic motor neuron disease that leads to progressive muscular atrophy and muscle weakness. In December 2016, the Food and Drug Administration, and in June 2017, the European Medicines Agency approved the antisense oligonucleotide nusinersen for treatment of spinal muscular atrophy. Nusinersen has to be repeatedly administered intrathecally. Due to the clinical features of SMA, the application of the ASO by lumbar puncture can be challenging in symptomatic patients considering the frequently observed scoliosis, previous spine fusion surgeries, joint contractures, and respiratory insufficiency. To evaluate safety and feasibility of the intrathecal treatment in adolescent and adult SMA type 2 and 3 patients, we analyzed 93 lumbar punctures, monitored number of lumbar puncture attempts, duration of the procedure, injection site, and needle length. Oxygen saturation during the intervention, medication for sedation and local anesthesia, adverse events related to lumbar punctures, and macroscopic analysis of CSF were recorded. Moreover, we analyzed the use of CT-scans for performing lumbar punctures and its associated radiation exposure. Performing lumbar puncture for the intrathecal administration of nusinersen in adolescent and adult patients with later-onset SMA is feasible and safe, even in patients with complex spinal anatomies and respiratory insufficiency. To guarantee the quality of the procedure, we recommend establishing an experienced interdisciplinary team consisting of neurologists and/or neuropediatricians, anesthesiologists, orthopedic surgeons, and/or neuroradiologists.

Eosinophilic granuloma of the spine involving C1 and pulmonary infiltration in young children - Presentation of two cases with a follow-up over 10 years including review of the literature.

OBJECTIVES: The incidence of spinal eosinophilic granuloma in children is low. METHODS: Clinical case presentation of two children (♀ 18 months old, ♂ 16 months old) complaining of acute torticollis. Follow-up period was 11 years in the female patient and 13 years in the male patient. RESULTS: The diagnostics certified a spinal eosinophilic granuloma: the girl had a multilevel spinal disease including the atlas, the boy a thoracic and pulmonary manifestation. Both were treated with chemotherapy with good clinical results. CONCLUSIONS: Overall, the above described is a very rare clinical entity. However, persisting torticollis in children should be clearly diagnosed.

Modified technique of transforaminal lumbar interbody fusion for segmental correction of lumbar kyphosis: a safe alternative to osteotomies?

BACKGROUND: Sagittal rebalancing of a fixated lumbar hypolordosis (kyphosis) is very important to gain satisfactory results. To correct a misalignment vertebral column resection or pedicle subtraction osteotomies are favored, disregarding the relatively high complication rates. The aim of this study was to evaluate the efficiency and safety of a new modified transforaminal lumbar fusion technique as an alternative. METHODS: We conducted a retrospective review (06/2011-06/2015 ) of a prospective database at an University hospital. Inclusion criteria were adult patients with a fixated lumbar hypolordosis and the need of monosegmental correction of more than 10° with an mTLIF. Exclusion criteria consisted of minor aged patients and polysegmental corrections. Study parameters were the perioperative complications and the achieved postsurgical lordosis. The follow up period was 6 months. RESULTS: A total of 11 patients could be included. The mean segmental lordosis was -2.3° ± 12.4° (range -22° to 14°) preoperative and 15.5° ± 10.5° (range 0° to 29°) postoperative. The degree of correction was 17° ± 5.7° in mean per treated segment (range 12° to 29°). No neurologic or vascular complications occurred. No substantial loss of correction or implant failure was noted during the 6-month follow-up. CONCLUSION: The modified transforaminal lumbar fusion technique is a safe method to correct a fixated lumbar kyphosis. The potential of segmental correction is comparable to pedicle subtraction osteotomies but sparing potentially healthy segments.

A survey on patients' knowledge and expectations during informed consent for spinal surgery: can we improve the shared decision-making process?

BACKGROUND: The informed medical consent in surgery requires to some point basic medical knowledge. The treating physicians while explaining the details and risks of the recommended procedure often imply this. We hypothesized, that patients do not have adequate medical understanding to decide about the ongoing therapy and its potential complications based on knowledge jeopardizing the patients' safety. METHODS: We conducted a retrospective analysis of a prospective database using a multiple choice questionnaire with 10 basic questions about anatomy, clinical symptoms and therapies of spinal diseases in our spine clinic at a German university hospital. Included were all patients at the spine clinic who agreed to the study and to fill in the questionnaire. Furthermore the patients age, mother tongue, the past spinal surgical history, the length of duration of symptoms and the patients education were inquired. The data were analyzed descriptive. RESULTS: Included were 248 patients with an average age of 59 years (16-88 a). 70 % of all patients used German as their mother tongue. 30 % of the included patients already had spinal surgery and suffered on average for 13.4 years because of their spinal disorder. Overall 32.6 % of all questions were answered correctly (range 0.8-68 %). A correlation of correctly answered questions and the patients' age, duration of symptoms, mother tongue, education and past surgical history could not be described. CONCLUSION: The percentage of correctly answered questions is almost as low as the likelihood of nearness in guessing. Having this in mind the patients do not choose any treatment option based on knowledge. The physicians need to provide more basic knowledge to the patients. This would increase the amount of successful therapies, content patients and the patients safety.

Preliminary investigations on intradiscal pressures during daily activities: an in vivo study using the merino sheep.

PURPOSE: Currently, no studies exist, which attest the suitability of the ovine intervertebral disc as a biomechanical in vivo model for preclinical tests of new therapeutic strategies of the human disc. By measuring the intradiscal pressure in vivo, the current study attempts to characterize an essential biomechanical parameter to provide a more comprehensive physiological understanding of the ovine intervertebral disc. METHODS: Intradiscal pressure (IDP) was measured for 24 hours within the discs L2-L3 and L4-L5 via a piezo-resistive pressure sensor in one merino sheep. The data were divided into an activity and a recovery phase and the corresponding average pressures for both phases were determined. Additionally, IDPs for different static and dynamic activities were analyzed and juxtaposed to human data published previously. After sacrificing the sheep, the forces corresponding to the measured IDPs were examined ex vivo in an axial compression test. RESULTS: The temporal patterns of IDP where pressure decreased during activity and increased during rest were comparable between humans and sheep. However, large differences were observed for different dynamic activities such as standing up or walking. Here, IDPs averaged 3.73 MPa and 1.60 MPa respectively, approximately two to four times higher in the ovine disc compared to human. These IDPs correspond to lower ex vivo derived axial compressive forces for the ovine disc in comparison to the human disc. For activity and rest, average ovine forces were 130 N and 58 N, compared to human forces of 400-600 N and 100 N, respectively. CONCLUSIONS: In vivo IDPs were found to be higher in the ovine than in the human disc. In contrast, axial forces derived ex vivo were markedly lower in comparison to humans. Both should be considered in future preclinical tests of intradiscal therapies using the sheep. The techniques used in the current study may serve as a protocol for measuring IDP in a variety of large animal models.

Can femoroacetabular impingement and hip dysplasia be distinguished by clinical presentation and patient history?

PURPOSE: Hip dysplasia and femoroacetabular impingement may both lead to disability and hip osteoarthritis. The purpose of the current study was to compare the two entities in order to define differences in their clinical presentation. METHODS: The clinical presentation and WOMAC items, subscales and overall sum score were compared between 37 patients with femoroacetabular impingement and 37 patients with hip dysplasia. RESULTS: The average duration of symptoms was 33.3 ± 31.6 months in patients with femoroacetabular impingement and 34.5 ± 39.0 months in patients with dysplasia (p = 0.885). The anterosuperior impingement test was positive in all patients with femoroacetabular impingement and in 92% of hip dysplasia patients (p = 0.061). Mean internal rotation and abduction was significantly less in patients with femoroacetabular impingement (p = 0.001 and 0.007). The WOMAC subscales for pain, stiffness, and functionality as well as the overall sum score were not significantly different between patients with femoroacetabular impingement and patients with hip dysplasia. The qualitative analysis of WOMAC items revealed that symptoms related to sitting were significantly more often rated to be present in femoroacetabular impingement than in hip dysplasia patients. In the quantitative analysis, only the item 'getting in or out of a car' was rated significantly more severe in patients with femoroacetabular impingement. CONCLUSION: In addition to obtaining a detailed history and examination, radiographic studies are needed for differentiation of the two entities and for the decision on treatment strategy.

Radiographic risk factors for labral lesions in femoroacetabular impingement.

BACKGROUND: Tears of the acetabular labrum can lead to pain, disability, and osteoarthritis. Several pathomechanisms have been proposed, including femoroacetabular impingement (FAI). Labral tears have been reported to occur in the presence of even subtle deformities of the acetabulum and femoral head-neck junction. QUESTIONS/PURPOSES: We analyzed the association of the extent of bony deformity and presence and extent of labral lesions in hips with FAI. PATIENTS AND METHODS: Radiographs of 123 hips in 116 patients receiving surgical treatment for FAI were analyzed and correlated to the presence and extent of labral lesions. Radiographic parameters of the acetabulum included acetabular index of the weightbearing zone, center-edge angle, inclination of the acetabulum, lateral head extrusion index, and retroversion. On the femoral side, neck-shaft angle, asphericity of the femoral head, superior and anterior alpha angle, offset, and offset ratio were measured. Osteoarthritis was graded according to Tönnis and Kellgren and Lawrence. Labral lesions were graded according to the modified Beck classification. A correlation between labral lesions and age, gender, affected side, type of impingement, and presence and extent of chondromalacia also was tested. RESULTS: No correlation was found between presence or extent of labral lesions and any radiographic parameter tested, except osteoarthritis classification. The severity of labral lesions correlated to the severity of acetabular chondromalacia as well as patient age (Beck Grade 0 versus Grade 1, Beck Grade 0 versus Grades 1 and 2). CONCLUSIONS: In the presence of impingement-inducing deformity, the extent of deformation is not associated with the incidence of labral lesions. Labral lesions are associated with early degenerative hip disease in FAI. LEVEL OF EVIDENCE: Level I, diagnostic study. See Guidelines for Authors for a complete description of levels of evidence.

Reliability of radiographic signs for acetabular retroversion.

Acetabular retroversion may contribute to femoroacetabular impingement and lead to osteoarthritis of the hip. Retroversion has been measured on computed tomography scans. In recent years, assessment of acetabular version on anteroposterior pelvic views has gained increasing attention. We therefore aimed to determine the reliability of radiographic signs of acetabular retroversion and its association with the rater's experience. Five orthopedic surgeons (o1 to o5) rated the crossover sign, ischial spine sign and posterior wall sign on X-rays of 40 hip joints. Also, we determined the rater's experience in recognizing acetabular retroversion with a questionnaire and correlated intraobserver reliability to the calculated experience score. The intraobserver results were 0.325 (o1), 0.848 (o2), 0.684 (o3), 0.701 (o4), and 1.000 (o5) for the crossover sign, 0.750 (o1), 0.890 (o2), 0.593 (o3), 0.483 (o4), and 0.946 (o5) for the posterior wall sign; and 0.578 (o1), 0.680 (o2), 0.595 (o3), 0.375 (o4), and 0.800 (o5) for the ischial spine sign. Interobserver reliability was 0.514 for the crossover, 0.633 for the posterior, and 0.543 for the ischial spine sign wall. The experience sum score correlated to the kappa results for the crossover (r = 0.527), posterior wall (r = 0.738), and ischial spine sign (r = 0.949). Assessing acetabular version on plain radiographs is subject to intra- and interindividual error and related to the observer's individual experience.

Posterior component impingement after lumbar total disc replacement: a radiographic analysis of 66 ProDisc-L prostheses in 56 patients.

STUDY DESIGN: Radiographic evaluation of lumbar total disc replacement (TDR). OBJECTIVES: To assess radiographically segmental angulation and mobility after lumbar TDR, to determine the rate of posterior component impingement, and to investigate the influence of implantation level and mono- versus bi-segmental implantations. SUMMARY OF BACKGROUND DATA: Polyethylene (PE)-wear can lead to inferior outcome after lumbar TDR due to aseptic loosening. One contributing factor might be increased segmental lordosis with component impingement. METHODS: Fifty-six consecutive patients with 66 ProDisc-L (Synthes Spine, Solothurn, CH) prostheses (46 mono-segmental, 10 bi-segmental) were evaluated radiographically. All prostheses had 6 degrees intrinsic angulation and a 10 mm PE-inlay. Segmental angulation and extension range of motion was measured twice on standing radiographs (neutral position and maximum extension) using the spike method. Component impingement was assumed if angulation of the prosthesis fins was >16 degrees . Intraobserver variability was assessed using Pearson correlation coefficient and 95% confidence interval (95% CI). RESULTS: The average angulation in neutral position was 9.9 degrees (+/-4.8 degrees ) and 9.9 degrees (+/-4.9 degrees ) at first and second measurement, respectively. In maximum extension it was 11.3 degrees (+/-4.9 degrees ) and 11 degrees (+/-4.9 degrees ). Pearson correlation coefficient suggested near perfect agreement (0.99) for measurement of angulation and good agreement for range of motion measurement (0.85). Ninety-five percent CI was +/-1.2 degrees and +/-1.4 degrees , respectively. Data were interpreted using absolute measurements (AM) and 95% CI, suggesting impingement if segmental angulation was >16 degrees (AM) and >17.2 degrees (95% CI). Regarding neutral position, 11% (AM) and 5% (95% CI) of the artificial discs showed component impingement. In extension, this increased to 15% (AM) and 9% (95% CI), respectively. Impingement was more frequent at L4/5 and in bi-segmental implantations. Extension according to AM was maintained in 52 prostheses (79%) with on average 1.4 degrees +/- 1.1 degrees . According to the 95% CI, which required a change of >1.4 degrees , extension was seen in 21 prostheses (32%) with on average 2.5 degrees +/- 1 degrees. CONCLUSION: Posterior component impingement was seen in a considerable number of implants. With regard to potential consequences like PE-wear, further studies are needed to investigate the correlation between radiographic and clinical findings.