The relationship between structural changes in paraspinal muscles and intervertebral disc and facet joint degeneration in the lumbar spine of rats.

BACKGROUND: Degenerative spine disease is one of the largest causes of disability worldwide and has a multifactorial aetiology. Determining the leading causes of this multifactorial disease could help create new treatment approaches. PURPOSE: Study the impact of degenerative changes in the paraspinal muscles caused by local (prolonged compression) or systemic (high-fat diet) factors on the structure of the intervertebral discs (IVDs) and facet joints of the lumbar spine in rats. METHODS: The study was conducted using two animal models to create degenerative changes in the paraspinal muscles of 10 white laboratory rats for 90 days and five control rats: 1) high-fat diet model (model 1) involved keeping the rats on a high calorie diet; 2) compression model (model 2) involved binding the paraspinal muscles from L2 to S1 using non-absorbable sutures. Histological analysis for the facet joints and IVDs of rats (at the L1-L4 level) with semi-quantitative analysis of the structure conducted used by degeneration grading system for IVDs and cartilage degeneration score (OARSI) for facet joint. RESULTS: In both models, 90 days after the experiment, the degenerative changes observed in the rats' IVDs were more severe in the annulus fibrosus than in the nucleus pulposus. The height of the IVD in model 1 did not differ from the control group, but in the model 2 was 1.3 times greater (p < 0.001) compared with control. Degenerative changes in the IVD were scored out 5.3 ± 1.7 in model 1 and 5.32 ± 2.1 in model 2 of a possible 16. The height of the articular cartilage of the facet joints was smaller by 1.5 times (p < 0.001) and 1.4 times (p < 0.001) in model 1 and model 2, respectively, compared to the control. Degenerative changes of facet joint were scored out 3.7 ± 0.6 in model 1 and 3.8 ± 0.6 in model 2 of five points according to the cartilage degeneration score. CONCLUSIONS: It was determined that rats who had structural changes in the lumbar paraspinal muscles as a result of being kept on a high-fat diet or subjected to prolonged compression for 90 days, showed degenerative changes in intervertebral discs and osteoarthritis in facet joints of lumbar spine.

Comparative study in vivo of the osseointegration of 3D-printed and plasma-coated titanium implants.

BACKGROUND: Total hip arthroplasty is a common surgical treatment for elderly patients with osteoporosis, particularly in postmenopausal women. In such cases, highly porous acetabular components are a favorable option in achieving osseointegration. However, further discussion is needed if use of such acetabular components is justified under the condition of normal bone mass. AIM: To determine the features of osseointegration of two different types of titanium implants [3-dimensional (3D)-printed and plasma-coated titanium implants] in bone tissue of a distal metaphysis in a rat femur model. METHODS: This study was performed on 20 white male laboratory rats weighing 300-350 g aged 6 mo. Rats were divided into two groups of 10 animals, which had two different types of implants were inserted into a hole defect (2 × 3 mm) in the distal metaphysis of the femur: Group I: 3D-printed titanium implant (highly porous); Group II: Plasma-coated titanium implant. After 45 and 90 d following surgery, the rats were sacrificed, and their implanted femurs were extracted for histological examination. The relative perimeter (%) of bone trabeculae [bone-implant contact (BIC%)] and bone marrow surrounding the titanium implants was measured. RESULTS: Trabecular bone tissue was formed on the 45th day after implantation around the implants regardless of their type. 45 d after surgery, group I (3D-printed titanium implant) and group II (plasma-coated titanium implant) did not differ in BIC% (83.51 ± 8.5 vs 84.12 ± 1 .73; P = 0.838). After 90 d, the BIC% was higher in group I (87.04 ± 6.99 vs 81.24 ± 7.62; P = 0.049), compared to group II. The relative perimeter of the bone marrow after 45 d did not differ between groups and was 16.49% ± 8.58% for group I, and 15.88% ± 1.73% for group II. Futhermore, after 90 d, in group I the relative perimeter of bone marrow was 1.4 times smaller (12.96 ± 6.99 vs 18.76 ± 7.62; P = 0.049) compared to the relative perimeter of bone marrow in group II. CONCLUSION: The use of a highly porous titanium implant, manufactured with 3D printing, for acetabular components provides increased osseointegration compared to a plasma-coated titanium implant.

DEVELOPMENT OF A MATHEMATICAL MODEL OF SELECTING THE EXTENT OF A SURGICAL INTERVENTION IN SPINAL TUMOR.

OBJECTIVE: The aim: To develop a mathematical model of selecting the extent of surgical intervention in the spinal tumors. PATIENTS AND METHODS: Materials and methods: The retrospective study included 237 patients with spinal tumors who underwent the following surgeries: vertebroplasty (V); vertebroplasty and spinal fixation (F+V); posterior spinal decompression and spinal fixation (F+F); vertebrectomy and replacement of vertebra by a cage with posterior spinal fixation (F+F+K). The mathematical model is based on the modified Spine Instability Neoplastic Score (SINS). The patients were divided into two clusters. Cluster analysis was used to build a diagnostic decision tree model. RESULTS: Results: The difference between two clusters is determined by the extent of surgical intervention, the grade of the vertebral lesion, epidural compression, and local kyphosis, and neurological signs as well. The cluster 1 included 115 patients with higher values of SINS compared to the cluster 2. All cases of vertebroplasty belonged to the cluster 2. In the cluster 1 cases of surgery of large extent: F+F; F+V; F+F+K. Analysis of the decision tree model for cluster 1 showed that a type of surgery was determined for 97 patients from 115 that relates to 84.3% of overall accuracy. The decision tree model have a high predictive accuracy for the surgery F+V and better indicators of coverage and predictive accuracy for the surgery F+F+K. CONCLUSION: Conclusions: Our study developed a decision tree model to optimize spinal neoplasm surgery, achieving 84.3% accuracy based on significant prognosis criteria. The model considers surgical type, neurological signs, vertebra lesion grade, and stage of epidural compression, potentially improving clinical outcomes.

Histological evaluation of the incorporation and remodeling of structural allografts in critical size metaphyseal femur defects in rats of different ages.

Insufficient bone regeneration is a common issue for patients with extensive bone damage, therefore the use of allografts is required. With increasing life expectancy, there is a higher risk of bone repair issues after fractures or orthopedic surgical intervention. We studied incorporation and remodeling of structural allografts in critical size metaphyseal femur defects in 52 rats aged 3-month-old and 12-month-old who underwent surgeries creating a bone defect, which was either filled with a structural allograft (3-month-old - 3moAllo; 12-month-old - 12moAllo) or left empty (3-month-old - 3moE; 12-month-old - 12moE). Histological analyses were performed 14, 28 and 90 days after the surgery. The percentage of bone and fibrous tissues, and allograft relative to the defect area was evaluated. The transmission electron microscopy was carried out 14 days after allograft implantation. When the defect was empty, slower bone regeneration was observed in 12moE rats versus 3moE, leading to sufficient irregularities in the anatomic structure of the femur 90 days after the surgery. When a structural allograft was used, the area of the fibrous tissue was larger in the defects of 12moAllo compared with 3moAllo rats 90 days after surgery. No age-related differences were found in the allograft remodeling and structures of the osteocytes, osteoblasts, and osteoclasts over the observation period. Evident issues with bone regeneration were found in critical size defects both of 12moE and 12moAllo rats. However, the allograft use allowed the bone maintaining anatomic structure 90 days after the surgery.

MODELS OF PARASPINAL MUSCLE DEGENERATION IN RATS: HIGH-FAT DIET AND PROLONGED COMPRESSION.

OBJECTIVE: The aim: To study the structural features of the lumbar m. multifidus and the m. psoas after keeping rats on a high-fat diet (obesity) or compressing their lumbar paraspinal muscles by binding the muscles using non-absorbable sutures. PATIENTS AND METHODS: Materials and methods: The study was performed on 2-month-old male rats (n=15) into three groups of 5: control group (normal diet without any surgical interventions), high-fat diet (model I: 40-45% kcal fat), and paraspinal muscles compression (model II: paraspinal muscles were tied from L2 to S1 with non-absorbable sutures Nurolon® 3). The experiment lasted for 90 days, after those fragments of the lumbar m. multifidus and m. psoas removed and histomorphometry analysis performed. RESULTS: Results: 12 weeks from the beginning of the experiment, the high-fat diet rats weighed, on average, 22% (p=0.001) more than the control group rats. Similar degenerative changes such as uneven muscle fibre width and sarcoplasm colouring, 'wavy' and swollen fibres, loss of striation, karyopyknosis were observed in the lumbar paraspinal muscles in both models. In high-fat diet group the fat area (%) in the m. multifidus was 1.8 times larger (р<0.001) and in the m. psoas was greater by 2.2 times (р<0.001) than in the control. Fibrous tissue replaced muscle fibres in m. multifidus in model II and was 12.66%. CONCLUSION: Conclusions: The relevance of the models is proven: after 3 months, it is possible to obtain degenerative changes in the muscle tissue that are extremely similar to those observed in the muscles of patients with degenerative spine diseases.

PERIACETABULAR BONE CHANGES AFTER TOTAL HIP ARTHROPLASTY WITH HIGHLY POROUS TITANIUM CUPS IN PATIENTS WITH LOW BONE MASS.

OBJECTIVE: The aim: To assess the bone remodeling around highly porous titanium cups TTM in patients with low bone mass one year after total hip arthroplasty (THA). PATIENTS AND METHODS: Materials and methods: In this prospective study were included 18 patients (18 hips), whom was performed primary THA with the use of TTM cups. According to T-score of Lumbar Spine, patients were divided into 2 groups: normal bone mineral density (BMD) (n=9) if T-score ≥ -1, and low BMD (n=9) if T-score < -1. According to DeLee and Charnley's model BMD in 3 periacetabular regions were evaluated 1 week and 1 year after THA. RESULTS: Results: One year after primary THA, BMD of all 3 periacetabular regions did not differ in patients of both groups comparing with initial data. One week after THA, it was found that BMD R1 and BMD R3 in low BMD group were lower by 1.4 times (p=0.035) and 1.5 times (р=0.001) respectively, BMD R2 did not differ from the normal BMD group. One year after THA it was found that in low BMD group BMD R1 and BMD R2 were lower by 1.5 times (р=0.005) and 1.3 times (р=0.050) respectively, BMD R3 did not differ from the group with normal BMD. CONCLUSION: Conclusions: The use of highly porous titanium cups TTM in patients with low bone mass did not lead to a bone loss in DeLee and Charnley periacetabular zones one year after THA. Consequently, the use of these cups in patients with low bone mass undergoing THA is a valuable treatment option.

Osseointegration of porous titanium and tantalum implants in ovariectomized rabbits: A biomechanical study.

BACKGROUND: Today, biological fixation of uncemented press-fit acetabular components plays an important role in total hip arthroplasty. Long-term stable fixation of these implants depends on the osseointegration of the acetabular cup bone tissue into the acetabular cup implant, and their ability to withstand functional loads. AIM: To compare the strength of bone-implant osseointegration of four types of porous metal implants in normal and osteoporotic bone in rabbits. METHODS: The study was performed in 50 female California rabbits divided into non-ovariectomized (non-OVX) and ovariectomized groups (OVX) at 6 mo of age. Rabbits were sacrificed 8 wk after the implantation of four biomaterials [TTM, CONCELOC, Zimmer Biomet's Trabecular Metal (TANTALUM), and ATLANT] in a 5-mm diameter defect created in the left femur. A biomechanical evaluation of the femur was carried out by testing implant breakout force. The force was gradually increased until complete detachment of the implant from the bone occurred. RESULTS: The breakout force needed for implant detachment was significantly higher in the non-OVX group, compared with the OVX group for all implants (TANTALUM, 194.7 ± 6.1 N vs 181.3 ± 2.8 N; P = 0.005; CONCELOC, 190.8 ± 3.6 N vs 180.9 ± 6.6 N; P = 0.019; TTM, 186.3 ± 1.8 N vs 172.0 N ± 11.0 N; P = 0.043; and ATLANT, 104.9 ± 7.0 N vs 78.9 N ± 4.5 N; P = 0.001). In the OVX group, The breakout forces in TANTALUM, TTM, and CONCELOC did not differ significantly (P = 0.066). The breakout force for ATLANT in the OVX group was lower by a factor of 2.3 compared with TANTALUM and CONCELOC, and by 2.2 compared with TTM (P = 0.001). In the non-OVX group, the breakout force for ATLANT was significantly different from all other implants, with a reduction in fixation strength by a factor of 1.9 (P = 0.001). CONCLUSION: TANTALUM, TTM, and CONCELOC had equal bone-implant osseointegration in healthy and in osteoporotic bone. ATLANT had significantly decreased osseointegration (P = 0.001) in healthy and in osteoporotic bone.

Evaluation of the bone morphology around four types of porous metal implants placed in distal femur of ovariectomized rats.

BACKGROUND: To compare structural features of the femoral bone of ovariectomized and non-ovariectomized rats after implantation of porous materials (TANTALUM, CONCELOC, TTM, ATLANT). METHODS: Experiments were carried out on 56 white laboratory female rats aged 6 months. Rats were randomly assigned into groups: sham-operated control group (SH) or ovariectomy group (OVX). Four different commercial implant materials (TTM, CONCELOC, TANTALUM, ATLANT) were placed into the defects (diameter 2.5 mm, depth 3.0 mm) in the distal metaphysis of femurs. Rats were sacrificed 45 days after surgery. Histological study was performed and the percentage of the bone area (BA%) around the implant at a distance of 500 µm in the cancellous area was measured. RESULTS: Formation of mature bone tissue of varying degrees around all of the implants was detected. In OVX rats cancellous bone defect zone was characterized by a high density of osteocytes on the surface. In the SH group, no differences in BA% among implant materials were found. In OVX rats, the BA% around ATLANT implants was 1.5-time less (p = 0.002) than around TANTALUM. The BA% around the rest of the materials was not statistically different. CONCLUSIONS: Bone formation around the studied porous titanium and tantalum materials in the osteoporosis model was lower than in normal bone. There were differences in bone formation around the different materials in the osteoporosis model, while in the normal bone model, these differences were absent.

Rabbit growth plate morphology in temporary bilateral blocking / Morfología de la placa de crecimiento de conejos durante bloqueo bilateral temporario

Blocking of the growth plate (GP) using plates with screws (tension band plating) is a modern method used to correct deformities and moderate leg length discrepancy in growing children. Determining the duration of temporary bilateral blocking without the occurrence of irreversible changes of GP is of paramount importance important. Methods: Two-month-old Californian breed male rabbits (n=30) were exposed to bilateral blocking of the distal GP of the right femur locking plates with screws for 3, 5, and 7 weeks. The fixators were removed after 5 and 7 weeks in 18 rabbits and 3 weeks after that, animals were sacri!ced. The contralateral limb was used as a control. Histological, histomorphometric, and X-ray analyses were performed. Results: During GP blocking, its height gradually decreased. This decreased was more pronounced after 7 weeks. Destructive changes progressed with an increase in the blocking duration. Three weeks after discontinuation of the bilateral blocking that lasted 5 weeks, the height of the GP signi!cantly increased 1.2 times on the lateral side and 1.9 times on the medial side (p<0.001) compared to the control. When blocking was discontinued after 7 weeks, the structure of the GP was partially restored after 3 weeks, the height of GP signi!cantly increased 1.2 times on the lateral side, and 1.07 times on the medial side (p<0.01) compared to the control. Conclusion: Restoration of the structuralfunctional features of the GP after the removal of the plates depends on the duration of temporary bilateral blocking, which must be taken into account in the clinical setting. (AU)

El bloqueo de la placa de crecimiento (PC) utilizando placas con tornillos (banda de tensión) es un método moderno utilizado para corregir deformidades y alteraciones moderadas en la longitud de las piernas en niños en crecimiento. Es de suma importancia determinar cuál debe ser la duración del bloqueo bilateral temporal sin que ocurran cambios irreversibles en la PC. Métodos: Conejos machos de raza californiana de dos meses de edad (n = 30) fueron expuestos al bloqueo bilateral de la PC distal colocando placas del fémur derecho con tornillos durante 3, 5 y 7 semanas. Los fijadores fueron retirados después de 5 y 7 semanas en 18 de los conejos, y 3 semanas después los animales fueron sacrificados. La extremidad contralateral se utilizó como control. Se realizaron análisis histológicos, histomorfométricos y de rayos X. Resultados: Durante el bloqueo de la PC, su altura disminuyó gradualmente. Esta disminución fue más pronunciada después de 7 semanas. Los cambios destructivos se incrementaron a medida aumentaba la duración del bloqueo. Tres semanas después de la interrupción del bloqueo bilateral que duró 5 semanas, la altura de la PC aumentó significativamente 1.2 veces en el lado lateral y 1.9 veces en el lado medial (p <0.001) en comparación con el control. Conclusión: La restauración de las características funcionales estructurales de la PC después de la extracción de las placas depende de la duración del bloqueo bilateral temporal, lo que debería tenerse en cuenta en el tratamiento clínico de estas alteraciones. (AU)