Two-screw osteosynthesis is biomechanically superior to single-screw osteosynthesis for type II odontoid fractures.

The data on the use of a one- or two-screw technique (1S, 2S) for ventral osteosynthesis of type II dens fractures are contradictory. The aim was to design an apparatus to mimic the physiological conditions and test stability with 1S, 2S, and a headless compression screw (HCS) for osteosynthesis of artificially created type II odontoid fractures. The apparatus was mounted on a Zwick materials testing machine. A total of 18 C1-2 specimens were stratified into three groups (1S, 2S, HCS). Odontoid fractures were artificially created, and osteosynthesis was performed. Each specimen was tested at loads increasing from 1 to 40 N. Screw loosening was observed visually, by fatigue data, and by a camera tracking system. Analysis of the Zwick data and the camera data revealed a significant higher stability after 2S compared to 1S and HCS treatment (Zwick data: p = 0.021, camera data: p < 0.001), while visible screw loosening showed a superiority of the 2S only over HCS (p = 0.038). The developed apparatus allowed the dynamic study of the atlantoaxial joint with a high approximation to physiological conditions. The results demonstrated superiority of the 2S over the 1S and HCS in biomechanical stability in the treatment of type II odontoid fractures.

Interleukin-6 as a critical inflammatory marker for early diagnosis of surgical site infection after spine surgery.

PURPOSE: Early diagnosis of surgical site infections (SSIs) could prevent surgical revision. Inflammatory markers (IMs), such as procalcitonin (PCT), interleukin-6 (IL-6), and tumor necrosis factor α (TNF-α), seem more accurate in diagnosing SSI than C-reactive protein (CRP) and white blood cell (WBC) count. The aim was to compare the predictive values of CRP, WBC count, PCT, IL-6, and TNF-α in SSI detection. METHODS: A total of 130 patients undergoing dorsal spondylodesis from 2019 to 2024 were enrolled in a prospective diagnostic study at a maximum care spine center. IMs were measured preoperatively and on the postoperative days (PODs) 1, 2, 3, 5, and 7. Patients with high suspicion of SSI underwent revision surgery. SSI was diagnosed when the microbiological evidence was positive. Patients were divided a posteriori into the non-infection and infection groups. RESULTS: IMs of 118 patients (66.9 ± 13.0 years, 61.0% females) were measured. Fifteen of the 118 patients (12.7%) developed an SSI. The groups differed with respect to existing hypertension, number of instrumented segments, region of surgery, CRPPOD1,7, PCTPOD7, and IL-6POD3,5,7. Binary logistic regression for SSI detection including these parameters showed an area under the curve (AUC) of 0.88 (95% CI 0.79-0.98; P < 0.001). The main effect for SSI detection was maintained by IL-6POD7 (odds ratio = 1.13; 95% CI 1.05-1.23; P = 0.001), which itself showed an AUC of 0.86 (95% CI 0.75-0.97). CONCLUSION: Compared to CRP, WBC count, PCT, and TNF-α, IL-6 seems to be the critical IM for the early detection of an SSI. TRIAL REGISTRATION: drks.de: DRKS00033773, date of registration: 29.02.2024, retrospectively registered; Postoperative Markers of Inflammation in Spine Surgery (POMIS) Trial.

The influence of pelvic tilt on sacral insufficiency fracture occurrence: Insights into the prevalence of high pelvic tilt among patients affected.

INTRODUCTION: Fragility fractures without significant trauma of the pelvic ring in older patients have an increasing incidence due to demographic change. Influencing factors other than osteoporotic bone quality that lead to an insufficiency fracture are not yet known. However, it is suspected that the pelvic tilt (PT) has an effect on the development of such an insufficiency fracture. This study explores the influence of the PTs in patients with insufficiency fractures of the posterior pelvic ring. MATERIALS AND METHODS: A total of 49 geriatric patients with fragility fractures of the pelvic ring were treated at a university hospital level-1 trauma center during a period between February and December 2023, and their fractures were classified according to the FFP classification of Rommens and Hofmann. Complete sets of computer tomography (CT) and radiological images were available to determine the PT angle of the patients. RESULTS: 34 FFP type 2 and 15 FFP type 3 classified patients were included in the study. Significant difference was seen in the pelvic tilt (PT) angle between the patient group with insufficiency fractures (n= 49; mean age: 78.02 ± 11.80) and the control group with lumbago patients (n= 53; mean age: 69.23 ± 11.23). The PT was significantly higher in the patients with insufficiency fractures (25.74° ± 4.76; p⁎⁎⁎⁎ ≤ 0.0001). CONCLUSIONS: The study demonstrates a significant extension of the PT angle of individuals with insufficiency fractures when compared to those with lumbago. The result suggests a potential association between pelvic tilt and fracture susceptibility. TRIAL REGISTRATION: A retrospective study about the influence of sagittal balance of the spine on insufficiency fractures of the posterior pelvic ring measured by the "pelvic tilt angle", DRKS00032120. Registered 20th June 2023 - Prospectively registered. Trial registration number DRKS00032120.

Effects of Iliosacral Joint Immobilization on Walking after Iliosacral Screw Fixation in Humans.

BACKGROUND: Pelvis fractures are commonly stabilized by surgical implants to facilitate their healing. However, such implants immobilize the iliosacral joint for up to a year until removal. We report how iliosacral joint immobilization affects the walking of patients. METHODS: The gaits of patients with immobilized sacroiliac joints after unstable pelvic fracture (n = 8; mean age: 45.63 ± 23.19; five females and three males) and sex- and age-matched healthy control individuals (n = 8; mean age: 46.50 ± 22.91; five females and three males) were recorded and analyzed using a motion capture system. The forces between the tread and feet were also recorded. Standard gait parameters as well as dynamic patterns of joint angles and moments of the lower extremities were analyzed using the simulation software OpenSim. RESULTS: With the exception of hip extensor strength, the monitored joint parameters of the patients showed task-dependent deviations during walking, i.e., plantarflexor force was increased when stepping on an elevated surface, as were hip flexion and extensor moments, knee flexion and extensor moments, as well as ankle dorsiflexion and the associated negative plantarflexor force during stance on the elevated surface. CONCLUSIONS: Iliosacral joint fixation causes reduced forward and upward propulsion and requires an extended range of hip motion in the sagittal plane. Patients show significant mobility limitation after iliosacral screw fixation.

Cervical Disc Arthroplasties Fail to Maintain Physiological Kinematics Under Lateral Eccentric Loads.

STUDY DESIGN: In vitro human cadaveric biomechanical analysis. OBJECTIVES: Optimization of prostheses for cervical disc arthroplasties (CDA) reduces the risk of complications. The instantaneous helical axis (IHA) is a superior parameter for examining the kinematics of functional spinal units. There is no comprehensive study about the IHA after CDA considering all 3 motion dimensions. METHODS: Ten human functional spinal units C4-5 (83.2 ± 7.9 yrs.) were examined with an established measuring apparatus in intact conditions (IC), and after CDA, with 2 different types of prostheses during axial rotation, lateral bending, and flexion/extension. Eccentric preloads simulated strains. The IHA orientation and its position at the point of rest (IHA0-position) were analyzed. RESULTS: The results confirmed the existing data for IHA in IC. Lateral preloads showed structural alterations of kinematics after CDA: During axial rotation and lateral bending, the shift of the IHA0-position was corresponding with the lateral preloads' applied site in IC, while after CDAs, it was vice versa. During lateral bending, the lateral IHA orientation was inclined, corresponding with the lateral preloads' applied site in the IC and oppositely after the CDAs. During flexion/extension, the lateral IHA orientation was nearly vertical in the IC, while after CDA, it inclined, corresponding with the lateral preloads' applied site. The axial IHA orientation rotated to the lateral preloads' corresponding site in the IC; after CDA, it was vice versa. CONCLUSION: Both CDAs failed to maintain physiological IHA characteristics under lateral preloads, revealing a new aspect for improving prostheses' design and optimizing their kinematics.

Effects of ligandrol as a selective androgen receptor modulator in a rat model for osteoporosis.

INTRODUCTION: The selective androgen receptor modulator ligandrol (LGD-4033 or VK5211) has been shown to improve muscle tissue. In the present study, the effect of ligandrol on bone tissue was investigated in ovariectomized rat model. MATERIALS AND METHODS: Three-month-old Sprague Dawley rats were either ovariectomized (OVX, n = 60) or left intact (NON-OVX, n = 15). After 9 weeks, OVX rats were divided into four groups: untreated OVX (n = 15) group and three OVX groups (each of 15 rats) treated with ligandrol orally at doses of 0.03, 0.3, or 3 mg/kg body weight. After five weeks, lumbar vertebral bodies (L), tibiae, and femora were examined using micro-computed tomographical, biomechanical, ashing, and gene expression analyses. RESULTS: In the 3-mg ligandrol group, bone structural properties were improved (trabecular number: 38 ± 8 vs. 35 ± 7 (femur), 26 ± 7 vs. 22 ± 6 (L), 12 ± 5 vs. 6 ± 3 (tibia) and serum phosphorus levels (1.81 ± 0.17 vs.1.41 ± 0.17 mmol/l), uterus (0.43 ± 0.04 vs. 0.11 ± 0.02 g), and heart (1.13 ± 0.11 vs. 1.01 ± 0.08 g) weights were increased compared to the OVX group. Biomechanical parameters were not changed. Low and medium doses did not affect bone tissue and had fewer side effects. Body weight and food intake were not affected by ligandrol; OVX led to an increase in these parameters and worsened all bone parameters. CONCLUSION: Ligandrol at high dose showed a subtle anabolic effect on structural properties without any improvement in biomechanical properties of osteoporotic bones. Considering side effects of ligandrol at this dose, its further investigation for the therapy of postmenopausal osteoporosis should be reevaluated.

Physiological Femoral Condylar Morphology in Adult Knees-A MRI Study of 517 Patients.

BACKGROUND: In the age of individualised arthroplasty, the question arises whether currently available standard implants adequately consider femoral condylar morphology (FCM). Therefore, physiological reference values of FCM are needed. The aim was to establish physiological reference values for anterior (ACO) and posterior condylar offset (PCO) as well as for the length of the medial (LMC) and lateral femoral condyles (LLC). METHODS: The knee joints of 517 patients (mean age: 52.3 years (±16.8)) were analysed retrospectively using MRI images. Medial (med) and lateral (lat) ACO and PCO, as well as LMC and LLC, were measured. All FCM parameters were examined for association with age, gender, side and osteoarthritis. RESULTS: Mean ACOmed was 2.8 mm (±2.5), mean ACOlat was 6.7 mm (±2.3), mean PCOmed was 25.7 mm (±4.6), mean PCOlat was 23.6 mm (±3.0), mean LMC was 63.7 mm (±5.0) and mean LLC was 64.4 mm (±5.0). Except for PCOmed, the mean values of all other FCM parameters were significantly higher in male knees compared to female knees. ACOmed and PCOmed showed significant side-specific differences. There were no significant differences in relation to age and osteoarthritis. CONCLUSION: The study showed significant differences in FCM side- and gender-specifically in adult knees. These aspects should be considered in the discussion of individual and gender-specific knee joint replacement.

Effect of a Contrast Agent on Bone Mineral Density Measurement in the Spine and Hip Using QCT-Conversion Factor Recommendation.

BACKGROUND: Osteoporosis causes an increased fracture risk. Clinically, osteoporosis is diagnosed late, usually after the first fracture occurs. This emphasizes the need for an early diagnosis of osteoporosis. However, computed tomography (CT) as routinely used for polytrauma scans cannot be used in the form of quantitative computed tomography (QCT) diagnosis because QCT can only be applied natively, i.e., without any contrast agent application. Here, we tested whether and how contrast agent application could be used for bone densitometry measurements. METHODS: Bone mineral density (BMD) was determined by QCT in the spine region of patients with and without the contrast agent Imeron 350. Corresponding scans were performed in the hip region to evaluate possible location-specific differences. RESULTS: Measurements with and without contrast agent administration between spine and hip bones indicate that the corresponding BMD values were reproducibly different between spine and hips, indicating that Imeron 350 application has a location-specific effect. We determined location-specific conversion factors that allow us then to determine the BMD values relevant for osteoporosis diagnosis. CONCLUSIONS: Results show that contrast administration cannot be used directly for CT diagnostics because the agent significantly alters BMD values. However, location-specific conversion factors can be established, which are likely to depend on additional parameters such as the weight and corresponding BMI of the patient.

Combination of vertebral bone quality scores from different magnetic resonance imaging sequences improves prognostic value for the estimation of osteoporosis.

BACKGROUND CONTEXT: Recent findings revealed a correlation between vertebral bone quality based on T1-weighted (VBQT1) magnetic resonance imaging (MRI) and volumetric bone mass density (vBMD) measured using quantitative computerized tomography. The coherence of VBQ for other MRI sequences, such as T2 or short tau inversion recovery (STIR), has not been examined. The combination of different VBQs has not been studied. PURPOSE: The aims of the study were to confirm the correlation between VBQT1 and vBMD and to examine VBQs from other MRI sequences and their combination with vBMD. STUDY DESIGN/SETTING: This was a retrospective cross-sectional study. PATIENT SAMPLE: The sample consisted of patients older than 18 years, who received treatment at a level-one university spine center of the German Spine Society for degenerative or traumatic reasons in 2017-2021. OUTCOME MEASURES: The outcome measures were the correlation of VBQs from different MRI sequences with vBMD and the association of VBQs with osteopenia/osteoporosis. METHODS: Patients' VBQ was calculated based on the signal intensities of the vertebral bodies L1-4 in T1-, T2-, and STIR-weighted MRI. The VBQ was standardized according to the signal intensity of the cerebrospinal fluid. The vBMD was determined using data from a calibrated scanner (SOMATOM Definition AS+) and processed with CliniQCT (Mindways Software, Inc., USA). Groups were divided according to vBMD into the following groups: (I) osteoporosis/osteopenia (< 120 mg/m3) and (II) healthy (≥120 mg/m3). An analysis of the correlation between various VBQs and vBMD as well as receiver operating characteristic (ROC) and binary regression analyses were performed for the prediction of osteoporosis/osteopenia. RESULTS: We included 136 patients (women: 56.6%) in the study (69.7 ± 15.0 years). According to vBMD, 108 patients (79.4%) had osteoporosis/osteopenia. Women were affected significantly more often than men (p = .045) and had significantly higher VBQT1 and VBQT2 values than men (VBQT1: p = .048; VBQT2: p = .013). VBQT1 and VBQT2 values were significantly higher in patients with osteoporosis/osteopenia than in healthy persons (VBQT1: p<.001; VBQT2: p = .025). VBQT1 and VBQT2 were significantly negatively correlated with vBMD with a moderate effect size (p<.001), while VBQSTIR was not significantly correlated with vBMD, although it showed a positive coherence. The combination of different VBQs in terms of VBQT1 × VBQT2 / VBQSTIR distinctly increased the effect size of the negative correlation with vBMD compared to VBQ alone. A cutoff value for VBQT1 × VBQT2 / VBQSTIR of 2.9179 achieved a sensitivity of 80.0%, a specificity of 75.0%, and an area under the curve (AUC) of 0.775 for the determination of osteoporosis. The mathematical model derived from the binary logistic regression showed an excellent AUC of 0.846. CONCLUSIONS: This study confirms a significant correlation between VBQT1 and vBMD. The combination of VBQs from different MRI sequences enhances the prognostic value of VBQ for the determination of osteoporosis. While safe clinical application of VBQ for the determination of osteoporosis requires further validation, VBQ might offer opportunistic estimation for further diagnostics.

Physiological Offset Parameters of the Adult Shoulder Joint-A MRI Study of 800 Patients.

Background: Humeral offset (HO) and glenoidal offset (GO) are important morphological parameters in diagnostics and therapy for shoulder pathologies. However, physiological reference values have not yet been sufficiently determined. The aim of the present study was to establish physiological reference values for shoulder offset parameters (SOPs). Methods: MRI images of the shoulder joints of 800 patients (mean age: 50.13 years [±16.01]) were analysed retrospectively. HO, GO, lateral glenoidal humeral offset (LGHO), humeral shaft axis offset (HAO) and cortical offset (CO) were measured. SOPs were examined for associations with age, gender, side and osteoarthritis. Results: The mean HO was 26.19 (±2.70), the mean GO was 61.79 (±5.67), the mean LGHO was 54.49 (±4.69), the mean HAO was 28.17 (±2.82) and the mean CO was 16.70 (±3.08). For all SOPs, significantly higher values were measured in male shoulders. There was a significantly (p < 0.001) higher mean value for HO, GO and LGHO in right shoulders. There was a significant correlation between age and LGHO, and HAO and CO, but not between age and HO or GO. Shoulders with osteoarthritis and non-osteoarthritis did not differ in the mean value of HO, GO, LGHO and HAO, except for CO (p = 0.049). Conclusion: Reference values for SOPs in the adult shoulder joint were determined for the first time. Significant gender-specific differences were found for all measured SOPs. In addition, it was seen that for some SOPs, the joint side and the patient's age has to be taken into account in shoulder diagnostics and surgery.

Can You Feel it? - Correlation Between Intraoperatively Perceived Bone Quality and Objectively Measured Bone Mineral Density.

STUDY DESIGN: clinical study. OBJECTIVES: Loosening of pedicle screws is a frequent complication in patients with osteoporosis. The indication for additional stabilization, such as cement augmentation, is more often based on the subjective intraoperative feeling of the surgeon than on a preoperative bone mineral density (BMD) measurement. Aim was to evaluate the correlation of the intraoperative perceived bone quality in comparison to the objectively measured BMD. METHODS: A total of 62 patients undergoing dorsal stabilization using pedicle screws at a level-1 trauma center were analyzed. The preoperative CT scan measured each instrumented vertebra's pedicle size and BMD. During the surgery, the perceived screw stability was graded by the respective surgeon for each screw. RESULTS: 204 vertebral bodies were evaluated. Looking at all implanted screws a significant correlation between the measured BMD and the perceived screw stability was found (Resident r = .450; R2 = .202; P < .001/Attending r = .364; R2 = .133; P < .001), but there was no significant correlation in the osteoporotic patients (Resident P = .148 / Attending P = .907). The evaluation of the screws implanted in osteoporotic vertebrae showed that the surgeons considered a total of 31% of these screws to be sufficiently stable. CONCLUSIONS: There was no significant correlation between the measured BMD and the perceived pedicle screw stability in the group with osteopenic / osteoporotic bone (<100 mg/cm³). The results indicate that it is not possible to reliably determine the bone quality and the resulting screw stability in patients with reduced BMD. The preoperative measurement of the BMD should become a crucial part of preoperative planning.

Long-term Quality of Life after Fusion of the Ventral Thoracic and Lumbar Spine.

BACKGROUND: Cage implantations and autologous pelvic bone grafts are common surgical procedures to fuse the spine in cases of spinal disorders such as traumatic fractures or degenerative diseases. These surgical methods are designed to stably readjust the spine and to prevent late detrimental effects such as pain or increasing kyphosis. Benefits of these surgical interventions have been evaluated, but the long-term well-being of patients after the respective treatments has not yet been examined. This study was designed to evaluate the clinical outcome for patients who received iliac crest or cage implantations. MATERIAL AND METHODS: Forty-six patients with traumatic fractures after they obtained an anterior fusion in the thoracic or lumbar spine (12 cages; mean age: 54.08 years; 34 pelvic bone grafts; mean age: 42.18 years) were asked to participate in the survey using a precast questionnaire according the Visual Analog Scale (VAS) Spine Score. Twenty-nine of them provided the data requested. RESULTS: Evaluation of the VAS scores of the patients, reporting at least 1 year after the surgery, revealed that cage implantations led to significantly better results with respect to all aspects of their daily life such as pain sensing, capability to undertake physical activities and exercise as compared with patients with autologous pelvic bone graft. Patients with autologous pelvic bone graft treatment reported a particularly poor overall satisfaction level concerning their long-term well-being. CONCLUSIONS: Patients with cage implantation reported a higher degree of long-term well-being. The data provide evidence for a positive impact on the postsurgery quality of life after cage implantation.

Influence of Hyponatremia on Spinal Bone Quality and Fractures Due to Low-Energy Trauma.

Background and Objectives: Hyponatremia is the most common electrolyte disorder in elderly and associated with increased risk of falls. Clinical studies as well as small animal experiments suggested an association between chronic hyponatremia and osteoporosis. Furthermore, it has been assumed that subtle hyponatremia may be an independent fracture risk in the elderly. Therefore, this study was designed to evaluate the possible influence of chronic hyponatremia on osteoporosis and low-energy fractures of the spine. Materials and Methods: 144 patients with a vertebral body fracture (mean age: 69.15 ± 16.08; 73 females and 71 males) due to low-energy trauma were treated in a level one trauma center within one year and were included in the study. Chronic hyponatremia was defined as serum sodium < 135 mmol/L at admission. Bone mineral density (BMD) of the spine was measured using quantitative computed tomography in each patient. Results: Overall, 19.44% (n = 28) of patients in the low-energy trauma group had hyponatremia. In the group with fractures caused by low-energy trauma, the proportion of hyponatremia of patients older than 65 years was significantly increased as compared to younger patients (p** = 0.0016). Furthermore, there was no significant gender difference in the hyponatremia group. Of 28 patients with chronic hyponatremia, all patients had decreased bone quality. Four patients showed osteopenia and the other 24 patients even showed osteoporosis. In the low-energy trauma group, the BMD correlated significantly with serum sodium (r = 0.396; p*** < 0.001). Conclusions: The results suggest that chronic hyponatremia affects bone quality. Patients with chronic hyponatremia have an increased prevalence of fractures after low-energy trauma due to a decreased bone quality. Therefore, physicians from different specialties should focus on the treatment of chronic hyponatremia to reduce the fracture rate after low-energy trauma, particularly with elderly patients.

Combatting AMR: A molecular approach to the discovery of potent and non-toxic rhenium complexes active against C. albicans-MRSA co-infection.

Antimicrobial resistance (AMR) is a major emerging threat to public health, causing serious issues in the successful prevention and treatment of persistent diseases. While the problem escalates, lack of financial incentive has lead major pharmaceutical companies to interrupt their antibiotic drug discovery programs. The World Health Organisation (WHO) has called for novel solutions outside the traditional development pathway, with emphasis on new classes of active compounds with non-classical mechanisms of action. Metal complexes are an untapped source of antibiotic potential owing to unique modes of action and a wider range of three-dimensional geometries as compared to purely organic compounds. In this study, we present the antimicrobial and antifungal efficacy of a family of rhenium tricarbonyl diimine complexes with varying ligands, charge and lipophilicity. Our study allowed the identification of potent and non-toxic complexes active in vivo against S. aureus infections at MIC doses as low as 300 ng/mL, as well as against C. albicans-MRSA mixed co-infection. The compounds are capable of suppressing the C. albicans morphogenetic yeast-to-hyphal transition, eradicating fungal-S. aureus co-infection, while showing no sign of cardio-, hepato-, hematotoxiciy or teratogenicity.

Cage or Pelvic Graft-Study on Bony Fusion of the Ventral Thoracic and Lumbar Spine in Traumatic Vertebral Fractures.

Background and Objectives: Stabilization of the spine by cage implantation or autologous pelvic bone graft are surgical methods for the treatment of traumatic spine fractures. These methods serve to stably re-adjust the spine and to prevent late detrimental effects such as pain or increasing kyphosis. They both involve ventral interventions using interbody fusion to replace the intervertebral disc space between the vertebral bodies either by cages or autologous pelvic bone grafts. We examined which of these methods serves the patients better in terms of bone fusion and the long-term clinical outcome. Materials and Methods: Forty-six patients with traumatic fractures (12 cages; mean age: 54.08/34 pelvic bone grafts; mean age: 42.18) who received an anterior fusion in the thoracic or lumbar spine were included in the study. Postoperative X-ray images were evaluated, and fusion of the stabilized segment was inspected by two experienced spine surgeons. The time to discharge from hospital and gender differences were evaluated. Results: There was a significant difference of the bone fusion rate of patients with autologous pelvic bone grafts in favor of cage implantation (p = 0.0216). Also, the stationary phase of patients who received cage implantations was clearly shorter (17.50 days vs. 23.85 days; p = 0.0089). In addition, we observed a significant gender difference with respect to the bony fusion rate in favor of females treated with cage implantations (p < 0.0001). Conclusions: Cage implantations after spinal fractures result in better bony fusion rates as compared to autologous pelvic bone grafts and a shorter stay of the patients in the hospital. Thus, we conclude that cage implantations rather than autologous pelvic bone grafts should be the preferred surgical treatment for stabilizing the spine after fracture.

The impact of bilateral facetectomy on the instantaneous helical axis of the functional thoracic spinal unit T4-5 during axial rotation.

The location of the instantaneous helical axis (IHA) and the impact of the facet joints (FJ) on the kinematics in the thoracic spine remain inconclusive. This study aimed to examine the IHA in the functional spinal unit (FSU) T4-5 during axial rotation in intact conditions and after bilateral facetectomy. Four human T4-5 FSUs were examined with an established 6D measuring apparatus in intact conditions and after bilateral facetectomy. The IHA's parameters migration, location, and direction in the horizontal plane were calculated. Defined preloads in different positions were applied. Under the intact conditions, the IHA migrated about 4 mm and from one to the contralateral side according to the applied preload. The location of the IHA was observed in the anterior part of the spinal canal. After bilateral facetectomy, the location of the IHA shifted ventrally about 10 mm compared to the intact conditions. Under intact conditions, the direction of the IHA was minimally dorsally reclined. After bilateral facetectomy, the IHA was significantly more ventrally inclined. The study determined the location of the IHA under intact conditions at the anterior part of the spinal canal. The IHA of the FSU T4-5 is substantially influenced by the guidance of the FJs.

Inhibition of Lipoxygenases Showed No Benefit for the Musculoskeletal System in Estrogen Deficient Rats.

Background: In previous studies, we reported the beneficial impact of two lipoxygenase-inhibitors, Baicalein and Zileuton, on osteoporotic bone in a postmenopausal rat model. Whereas subcutaneous Baicalein predominantly improved cortical bone, Zileuton enhanced vertebral and femoral trabecular bone. In this study, we aimed to reveal whether the oral administration of Baicalein caused similar effects on bone and whether a combined administration of Baicalein and Zileuton could act synergistically to ameliorate the formerly reported effects in the musculoskeletal system. Methods: We treated ovariectomized (OVX) female Sprague-Dawley rats either with Baicalein (10mg/kg BW), Zileuton (10mg/kg BW) or a combination of both (each 10mg/kg BW) for 13 weeks and compared with untreated OVX and NON-OVX groups (n=12-16 rats per group). Lumbar vertebral bodies and femora were analyzed. Tibiae were osteotomized, plate-stabilized (at week 8 after OVX) and likewise analyzed by biomechanical, histological, micro-computed tomographical and ashing tests. The skeletal muscle structure was analyzed. Results: Oral administration of Baicalein did not confirm the reported favorable cortical effects in neither vertebra nor femur. Zileuton showed a beneficial effect on trabecular vertebra, while the femur was negatively affected. Callus formation was enhanced by all treatments; however, its density and biomechanical properties were unaltered. Lipoxygenase inhibition did not show a beneficial effect on skeletal muscle. The combination therapy did not ameliorate OVX-induced osteoporosis but induced even more bone loss. Conclusions: The preventive anti-osteoporotic treatments with two lipoxygenase inhibitors applied either alone or in combination showed no benefit for the musculoskeletal system in estrogen deficient rats.

Ostarine and Ligandrol Improve Muscle Tissue in an Ovariectomized Rat Model.

In postmenopausal women, hormonal decline changes muscle function and structure. The non-steroidal selective androgen receptor modulators (SARMs) Ostarine (OS) and Ligandrol (LG) have been shown to increase muscle mass and physical function while showing a relative low risk profile. Information about their effects on muscle structure and metabolism is lacking. To analyze this, two experiments were performed using ovariectomized rats as a standard model for postmenopausal conditions. In each experiment, 3-month old Sprague-Dawley rats were divided into five groups (n = 12 to 15). One group remained intact (Non-OVX), the other four groups were ovariectomized (OVX) and remained untreated for eight (OS Experiment) or nine (LG Experiment) weeks. Thereafter, rats of three of the four OVX groups were treated with OS or LG (with doses of 0.04, 0.4, or 4 mg/kg body weight/day) for 5 weeks. Then, uterus, gastrocnemius, and soleus muscles were weighed, fiber size, capillary density, and enzyme activity (lactate dehydrogenase [LDH], citrate synthase [CS], and complex I) were analyzed. In the LG experiment, intramuscular fat content was determined in the quadriceps femoris muscle. All OS treatments resulted in a higher capillary density in the gastrocnemius and longissimus muscles compared with the Non-OVX and the OVX rats, whereas all LG treatments showed a higher capillary density compared with the Non-OVX group. Muscle fiber size and distribution patterns were not changed under either SARM. The CS activity was higher in the longissimus muscle under OS treatment. LG resulted in a higher activity of CS in the gastrocnemius and of LDH in the longissimus muscle. Both SARMs showed an uterotrophic effect, OS at 4 and 0,4 mg dosages, LG at 4 mg dosage. In sum, beneficial effect on muscle vascularization was observed for both SARMs with a stronger impact for OS. LG showed more effect on muscle metabolism. However, a higher muscle weight and intramuscular fat content observed after LG treatment (4 mg) as well as an uterotrophic effect of both SARMs at higher dosages could be considered as an unfavorable side effects and might be a limitation for their application at these dosages.

Total disc arthroplasties alter the characteristics of the instantaneous helical axis of the cervical functional spinal units C3/C4 and C5/C6 during flexion and extension in in vitro conditions.

Total disc arthroplasty (TDA) increases the risk of adjacent segment disease (ASD). Kinematic analyses are necessary to compare the intact condition (IC) with alterations after TDA to develop better prostheses. A well-established 6D measuring apparatus (resolution < 2.4 µm; 400 positions/cycle) was used. Kinematics of the flexion and extension of 8 human cervical spine segments (cFSU) C3/C4 and C5/C6 (67.9 ± 13.2 y) were analyzed in the IC and after TDA (Bryan® Cervical Disc [B-TDA], Prestige LP® Cervical Disc [P-TDA]). The migration of the instantaneous helical axis (IHA) and the stiffness of the segments were calculated. Analyses demonstrated a stretched U-curved IHA migration in the sagittal plane. The IHA positions were significantly more cranial in cFSU C5/C6 than in C3/C4 in IC and after either TDA (IC: p < 0.001; B-TDA: p = 0.001; P-TDA: p = 0.045). In cFSU C3/C4 IHA positions shifted anteriocranially after either TDA (p < 0.001). In cFSU C5/C6, the IHA positions were significantly more anterocranial after B-TDA than in IC and after P-TDA (anterior: p < 0.001; cranial: p = 0.005). After B-TDA, the IHA migration path length was significantly longer in cFSU C3/C4 than in C5/C6 (p = 0.007) and longer than in IC in both cFSU (C3/C4: p = 0.047; C5/C6: p < 0.001). Stiffness was increased after both TDA. Various kinematic alterations were observed after both TDA. Increased translation and IHA position shifting after both TDA might indicate abnormal strain and a derogated benefit of TDA. These results imply the most abnormal strain after B-TDA. The lower cFSU might be more susceptible to alterations after TDA than the upper cFSU.