Development and biomechanical analysis of an axially controlled compression spinal rod for lumbar spondylolysis.

BACKGROUND: To elucidate the differences in mechanical performance between a novel axially controlled compression spinal rod (ACCSR) for lumbar spondylolysis (LS) and the common spinal rod (CSR). METHODS: A total of 36 ACCSRs and 36 CSRs from the same batch were used in this study, each with a diameter of 6.0 mm. Biomechanical tests were carried out on spinal rods for the ACCSR group and on pedicle screw-rod internal fixation systems for the CSR group. The spinal rod tests were conducted following the guidelines outlined in the American Society for Testing and Materials (ASTM) F 2193, while the pedicle screw-rod internal fixation system tests adhered to ASTM F 1798-97 standards. RESULTS: The stiffness of ACCSR and CSR was 1559.15 ±â€…50.15 and 3788.86 ±â€…156.45 N/mm (P < .001). ACCSR's yield load was 1345.73 (1297.90-1359.97) N, whereas CSR's was 4046.83 (3805.8-4072.53) N (P = .002). ACCSR's load in the 2.5 millionth cycle of the fatigue four-point bending test was 320 N. The axial gripping capacity of ACCSR and CSR was 1632.53 ±â€…165.64 and 1273.62 ±â€…205.63 N (P = .004). ACCSR's torsional gripping capacity was 3.45 (3.23-3.47) Nm, while CSR's was 3.27 (3.07-3.59) Nm (P = .654). The stiffness of the pedicle screws of the ACCSR and CSR group was 783.83 (775.67-798.94) and 773.14 (758.70-783.62) N/mm (P = .085). The yield loads on the pedicle screws of the ACCSR and CSR group was 1345.73 (1297.90-1359.97) and 4046.83 (3805.8-4072.53) N (P = .099). CONCLUSION: Although ACCSR exhibited lower yield load, stiffness, and fatigue resistance compared to CSR, it demonstrated significantly higher axial gripping capacity and met the stress requirement of the human isthmus. Consequently, ACCSR presents a promising alternative to CSR for LS remediation.

Age-different BMSCs-derived exosomes accelerate tendon-bone interface healing in rotator cuff tears model.

BACKGROUND: Rotator cuff tears (RCTs) are culprit of shoulder pain and dysfunction. Tendon-bone interface (TBI) mal-healing is an essential contributor to retear after RCTs. Consequently, present project was conducted to investigate the role of bone marrow mesenchymal stem cells (BMSCs)-derived exosomes on TBI healing. METHOD: Young BMSCs (Y-BMSCs) and Aged BMSCs (A-BMSCs) were isolated from Young (3-month-old) and old (24-month-old) SD rats, and their-derived exosomes (A-BMSCs-exo and Y-BMSCs-exo) were identified. RCTs model was established, and A-BMSCs-exo and Y-BMSCs-exo were injected at the rotator cuff using hydrogel as a vehicle. Pathological changes of TBI were observed by HE, Sirius Red and Oil Red O staining. Western blotting and RT-qPCR were applied to assess the expression of extracellular matrix (ECM)-, tendon cell (TCs)-, osteogenic-, tendon-derived stem cell (TDSCs)- and angiogenic-associated proteins and mRNAs in TBI. RESULT: Y-BMSCs exhibited increased activity, osteogenic and lipogenic abilities than A-BMSCs. After A-BMSCs-exo and Y-BMSCs-exo treatment, TBI displayed massive sharpey's fibers growing along the tendon longitudinally, and a collagen fiber-chondrocyte migration zone forming a typical tendon-noncalcified fibrocartilage-calcified fibrocartilage-bone structure. A-BMSCs-exo and Y-BMSCs-exo significantly upregulated the expression of collagen Col I/II/III, Aggrecan, TNMD, SCX, Runx2, OPN, CD45, Sox2, CD31 and VEGFR2 in TBI. In vitro, A-BMSCs-exo and Y-BMSCs-exo significantly enhanced the activity of TCs and TDSCs, TDSCs stemness, and reduced the osteogenic and lipogenic capacity of TDSCs. The effect of Y-BMSCs-exo was significantly stronger than that of A-BMSCs-exo. CONCLUSION: BMSCs-derived exosomes facilitate ECM remodeling, osteogenic differentiation, angiogenesis, and stemness of TDSCs, thereby accelerating TBI healing in RCTs, with better outcomes using young individual-derived BMSCs.

Experimental study of a 3D-printing technique combined with biphasic calcium phosphates to treat osteonecrosis of the femoral head in a canine model.

OBJECTIVE: This study was aimed to use a digital design of 3D-printing technology to create a surgical navigation template. At the same time, biphasic calcium phosphate (BCP) was applied to treat osteonecrosis of the femoral head (ONFH) in animal models, based on accurate positioning of necrotic lesions in the navigation templates and observation of its therapeutic effect. METHODS: Fifteen healthy adult male and female beagle dogs weighing 20 + 2 kg were randomly divided into three groups (n = 5) after establishing a model of ONFH using the liquid nitrogen freezing method. Each model underwent necrotic lesion creation and BPC implantations on one side of the femoral head and only necrotic lesion creation on the other side of the femoral head. Each group underwent CT examination, gross observation, histological examination and immunohistochemical staining at 6 weeks, 12 weeks and 18 weeks postoperatively. RESULTS: At weeks 6, 12, and 18, CT and gross examination showed that the necrotic area in the experimental group was basically intact and had been completely raised by BCP material. In the control group, there were signs of bone repair in the femoral head, but there were still large bone defects and cavities. At week 18, extensive collapse of the cartilage surface was observed. Through histological examination, in the experimental group at 12 and 18 weeks, a large number of new and reconstructed bone trabeculae containing a large amount of collagen fibres were observed (P < 0.05), while in the control group, there was extensive necrosis of the bone trabeculae without cellular structural areas. Immunohistochemical examination observation: A large number of CD31-positive cells were observed in the experimental group at 6 weeks, gradually decreasing at 12 and 18 weeks (P < 0.05), while a small number of CD31-positive cells were observed in the control group at 18 weeks. CONCLUSION: The 3D-printed navigation template can accurately locate ONFH lesions. Implantation of BCP material can effectively play a supporting role, prevent the collapse of the loading surface, and induce bone formation and angiogenesis to some extent.

Incidence of lumbar spondylolysis in athletes with low back pain: A systematic evaluation and single-arm meta-analysis.

BACKGROUND: Low back pain (LBP) is a common chief complaint from athletes. Lumbar spondylolysis (LS) is a common sport injury. Severe LS is likely to cause spinal instability, resulting in lumbar spondylolisthesis or lumbar disc herniation, and even damage to the spinal nerve roots. The incidence of LS is approximately 5% in the adult population, and nearly half of young athletes with LBP are diagnosed with LS. This meta-analysis analyzed the incidence of LS in athletes with LBP. METHODS: PubMed, Embase, Cochrane (Cochrane Central Register of Controlled Trials), and Web of Science databases were systematically searched for published case report and retrospective analyses related to the topic from the date of database creation to January 1,2023. Relevant literature was screened and information extracted, and risk of bias was assessed for included studies using the methodological index for non-randomized-studies scale. Single-arm Meta-analysis was performed using R4.04 software. Heterogeneity was quantified by Cochran Q test and Higgins I2. Funnel plots were used to visualize publication bias, and Egger test and Begg test were used to statistical tests. RESULTS: A total of 9 studies (835 patients) were included in this study. Meta-analysis revealed that the prevalence of LS in athletes with LBP was estimated at 41.7%, [95% CI = (0.28-0.55)], but this prevalence varied considerably with the gender and age of the athletes. CONCLUSION: The estimated prevalence of LS in athletes with LBP is 41.7%, and future correlations between the prevalence of LS in adolescent athletes worldwide need to be assessed from different perspectives, including biomechanical, hormonal, anatomical, behavioral, and gender differences.

[Recent progress in foot and ankle surgery].

The article focuses on the recent progress in foot and ankle surgery, including the diagnosis of disease, treatment protocols, outcomes, and evaluation tools as well as other innovations. New and accurate diagnostic modalities and measurements have undergone a breakthrough. Diagnostic modalities tend to be simpler and less expensive. Measurement tools also change to simpler and more accurate. The accuracy and efficacy of surgery and the minimally invasive method have become more popular and important. New treatments and basic research have also made breakthroughs.

Reconstruction of Moderate-Sized Hand Defects Using a Superficial Lateral Sural Artery Perforator Flap.

BACKGROUND: The skin on the lower leg has abundant perforators and, thus, is an excellent donor site for transplant tissue flaps. However, due to vascular variations and body positions, tissue flaps at the posterolateral proximal portion of the lower leg are rarely used for transplantation. This study reports our experience with the use of superficial lateral sural artery perforator (SLSAP) flaps in the repair of moderate-sized hand wounds. METHODS: From March 2012 to April 2015, the hand wounds of 15 patients were planned for repair using a superficial sural artery perforator flap. In total, 6 patients had a defect in the palm of the hand, 5 in the dorsum of the hand, and 3 in the finger; 1 patient sustained a contracture of the first web space. RESULTS: In 12 of the 15 cases, an SLSAP flap was successfully harvested. In the remaining 3 cases, the planned harvest of an SLSAP flap was converted to the harvest of a superficial medial sural artery perforator flap during the operation. The flaps ranged in area from 1.8 × 3.8 cm to 5.5 × 6.5 cm. Primary suture of the donor site was performed in all cases. Dissection of the muscular tissue was avoided. After the operation, venous crisis occurred in 1 case, and a partial area of necrosis developed at the distal end in 1 case. The flap survived in all other cases. CONCLUSIONS: Our experience showed that the SLSAP flap is suitable for reconstruction of moderate-sized hand defects.