Experimental study on the biomechanical stability of complex acetabular fractures in the quadrilateral area: application of a dynamic anterior titanium-plate screw system.

BACKGROUND AND OBJECTIVE: Complex acetabular fractures involving quadrilateral areas are more challenging to treat during surgery. To date, there has been no ideal internal fixation for these acetabular fractures. The purpose of this study was to evaluate the biomechanical stability of complex acetabular fractures using a dynamic anterior titanium-plate screw system of the quadrilateral area (DAPSQ) by simulating the standing and sitting positions of pelvic specimens. MATERIALS AND METHODS: Eight formal in-preserved cadaveric pelvises aged 30-50 years were selected as the research objects. First, one hip of the normal pelvises was randomly used as the control model (group B) for measurement, and then one hip of the pelvises was randomly selected to make the fracture model in the 8 intact pelvises as the experimental model (group A) for measurement. In group A, acetabular both-column fractures in the quadrilateral area were established, and the fractures were fixed by DAPSQ. The biomechanical testing machine was used to load (simulated physiological load) from 400 N to 700 N at a 1 mm/min speed for 30 s in the vertical direction when the specimens were measured at random in simulated standing or sitting positions in groups. The horizontal displacement and longitudinal displacement of the acetabular fractures in the quadrilateral area were measured in both the standing and sitting simulations. RESULTS: As the load increased, no dislocation or internal fixation breakage occurred during the measurements. In the standing position, the horizontal displacement of the quadrilateral area fractures in group A and group B appeared to be less than 1 mm with loads ranging from 400 N to 700 N, and there was no significant difference between group A and group B (p > 0.05). The longitudinal displacement appeared to be greater than 1 mm with a load of 700 mm in group A (700 N, 2 cases), and the difference was significant between group A and group B (p < 0.05). In the sitting position, the horizontal and longitudinal displacements of the quadrilateral areas were within 0.5 mm in group A and group B, and there was no significant difference between group A and group B (p > 0.05). CONCLUSION: For complex acetabular fractures in the quadrilateral area, DAPSQ fixation may provide early sitting stability, but it is inappropriate for patients to stand too early.

All-inside endoscopic semiautomatic running locked stitch technique shows favourable outcomes for acute Achilles tendon ruptures.

PURPOSE: The safety and reliability of endoscopic Achilles tendon rupture repair are still concerning aspects. This study's aim is to evaluate an all-inside endoscopic semiautomatic running locked stitch (Endo-SARLS) technique. METHODS: Forty cases with acute Achilles tendon rupture were treated with the all-inside Endo-SARLS technique between 2020 and 2021. Under endoscopic control, the proximal tendon stumps were stitched with the running locked method using a semiautomatic flexible suture passer. The threads of the high-strength suture were grasped through the paratenon subspace and then fixed into calcaneal insertion with a knotless anchor. Magnetic resonance imaging (MRI), surgical time and complications were assessed. Achilles Tendon Total Rupture Score (ATRS), Achilles Tendon Resting Angle (ATRA) and Heel Rise Height Scale (HRHS) were utilised to evaluate final outcomes. RESULTS: The average follow-up time was 25.4 ± 0.4 (range: 24-32) months. Appropriate tendon regeneration was observed on MRI after 12 months. At the final follow-up, the median value of ATRS score was 95 (interquartile range: 94, 98). Furthermore, there is no significant difference between the injured and contralateral side in the average ATRA (18.2 ± 1.8 vs. 18.3 ± 1.9°, ns) and median value of HRHS [14.5 (13.3, 15.5) vs. 14.8 (13.5, 15.6) cm, ns]. No infection and nerve injuries were encountered. Thirty-nine patients reported that they resumed casual sports activity after 6 months. One patient had a slight anchor cut-out, due to an addition injury, which was removed after 5 months. CONCLUSIONS: An all-inside Endo-SARLS technique showed promising clinical results for acute Achilles tendon ruptures. This procedure reduces the risk of sural nerve injuries while establishing a reliable connection between the tendon stumps. LEVEL OF EVIDENCE: Level IV.

Third-Generation Dynamic Anterior Plate-Screw System for Quadrilateral Fractures: Digital Design Based on 834 Pelvic Measurements.

Background and Objectives: To investigate the digital measurement method for the plate trajectory of dynamic anterior plate-screw system for quadrilateral plate (DAPSQ), and then design a third-generation DAPSQ plate that conforms to the needs of the Chinese population through collating a large sample anatomical data. Materials and Methods: Firstly, the length of the pubic region, quadrilateral region, iliac region, and the total length of the DAPSQ trajectory were measured by a digital measurement approach in 22 complete pelvic specimens. Then, the results were compared with the direct measurement of pelvic specimens to verify the reliability of the digital measurement method. Secondly, 504 cases (834 hemilateral pelvis) of adult pelvic CT images were collected from four medical centers in China. The four DAPSQ trajectory parameters were obtained with the digital measurement method. Finally, the third-generation DAPSQ plate was designed, and its applicability was verified. Results: There was no statistically significant difference in the four trajectory parameters when comparing the direct measurement method with the digital measurement method (p > 0.05). The average lengths of the pubic region, quadrilateral region, iliac region, and the total length in Chinese population were (60.96 ± 5.39) mm, (69.11 ± 5.28) mm, (84.40 ± 6.41) mm, and (214.46 ± 10.15) mm, respectively. Based on the measurement results, six models of the DAPSQ plate including small size (A1,A2), medium size (B1,B2), and the large size (C1,C2) were designed. The verification experiment showed that all these six type plates could meet the requirement of 94.36% cases. Conclusions: A reliable computerized method for measuring irregular pelvic structure was proposed, which not only provided an anatomical basis for the design of the third-generation DAPSQ plate, but also provided a reference for the design of other pelvic fixation devices.

Didepside Formation by the Nonreducing Polyketide Synthase Preu6 of Preussia isomera Requires Interaction of Starter Acyl Transferase and Thioesterase Domains.

Orsellinic acid (OA) derivatives are produced by filamentous fungi using nonreducing polyketide synthases (nrPKSs). The chain-releasing thioesterase (TE) domains of such nrPKSs were proposed to also catalyze dimerization to yield didepsides, such as lecanoric acid. Here, we use combinatorial domain exchanges, domain dissections and reconstitutions to reveal that the TE domain of the lecanoric acid synthase Preu6 of Preussia isomera must collaborate with the starter acyl transferase (SAT) domain from the same nrPKS. We show that artificial SAT-TE fusion proteins are highly effective catalysts and reprogram the ketide homologation chassis to form didepsides. We also demonstrate that dissected SAT and TE domains of Preu6 physically interact, and SAT and TE domains of OA-synthesizing nrPKSs may co-evolve. Our work highlights an unexpected domain-domain interaction in nrPKSs that must be considered for the combinatorial biosynthesis of unnatural didepsides, depsidones, and diphenyl ethers.

Arthro-Broström with endoscopic retinaculum augmentation using all-inside lasso-loop stitch techniques.

BACKGROUND: There is still some controversy about the augmentation of the inferior extensor retinaculum after arthroscopic anterior talofibular ligament repair. The aim of this study was to evaluate the novel arthro-Broström procedure with endoscopic retinaculum augmentation using all-inside lasso-loop stitch techniques for chronic lateral ankle instability. METHODS: Thirty-four cases with grade-2 or grade-3 chronic anterior talofibular ligament lesions who underwent the novel arthro-Broström procedure with endoscopic retinaculum augmentation using all-inside lasso-loop stitch techniques were assessed retrospectively. A total of 30 cases (30 ankles) were followed up for a mean of 26.67 ± 4.19 months (range, 24-36 months). four cases were excluded due to insufficient medical records or loss of follow-up reports. The Cumberland Ankle Instability Tool scores, The Karlsson-Peterson scores and Visual Analogue Scale scores were evaluated before surgery and at the final follow-up time. Also, the results of stress fluoroscopic tests and complications were recorded. RESULTS: At the final follow-up, the average of the Cumberland Ankle Instability Tool scores, The Karlsson-Peterson scores and Visual Analogue Scale scores were 86.63 ± 6.69 (range, 77-100), 90.17 ± 4.64 (range, 85-100) and 0.53 ± 0.63 (range, 0-2), respectively. Moreover, the results of stress fluoroscopic tests were improved significantly after surgery. Mild keloid formation and/or knot irritation were observed in four cases. No wound infections, nerve injuries and recurrent instability were recorded. Also, no stiffness or arthritis of the subtalar joint was encountered. CONCLUSIONS: The arthro-Broström procedure combined with endoscopic retinaculum augmentation using all-inside lasso-loop techniques is reliable and safe due to the advantage of direct endoscopic visualization.

Arthroscopic Suture-Bridge Repair Technique for an Avulsion of the Talar Insertion of the Anterior Talofibular Ligament.

There are several studies about arthroscopic repair techniques for the lesion of the anterior talofibular ligament. However, the research concentrating on the avulsion of the talar insertion of the anterior talofibular ligament is very rare. Among 122 patients who suffered from recurrent ankle sprain and underwent arthroscopic anterior talofibular ligament repair from October 2016 to January 2019 in our hospital, 11 patients with an avulsion of the talar insertion of this ligament were diagnosed and then treated with the arthroscopic suture-bridge repair technique in the present study. The clinical outcomes were assessed using the Karlsson-Peterson score, Ankle and hindfoot score by American Orthopedic of Foot and Ankle Society, Sefton articular stability scale and Visual Analogue Scale. The complications were recorded at the time of observation. The median value of the follow-up time was 30 (range 18-36) months. At the final follow-up, the median value of the Karlsson-Peterson score, American Orthopedic of Foot and Ankle Society ankle-hindfoot score, and Visual Analogue Scale score was 90, 90, 1, respectively. Based on the Sefton stability scale, 10 cases were in the excellent or good category. No wound infections and no neurovascular injuries were encountered, also no case required revision surgery. Only 1 patient complained about mild local irritation at the knotless anchor site. The arthroscopic suture-bridge technique could be suitable for treatment of an avulsion of the talar insertion of the anterior talofibular ligament due to satisfactory activity recovery and few complications.

Open reduction and internal fixation of quadrilateral plate fractures in the elderly: association between initial fracture pattern and outcomes.

BACKGROUND: Acetabular fractures with medial displacement of the quadrilateral plate (QLP) are common in the elderly. The presence of QLP fractures greatly increase the surgical difficulty of acetabular fractures. This study aims to evaluate the clinical radiological outcomes of open reduction and internal fixation (ORIF) in QLP fractures in elderly patients and to investigate factors potentially affecting the result. METHODS: We conducted a retrospective study. A series of 37 consecutive patients with acetabular fracture involving the QLP aged 60 years and older who received ORIF between January 2010 and May 2019 were included. QLP fractures were classified according to Walid's classification system. Radiological outcomes were evaluated using Matta criteria and functional outcomes were assessed using the modified Merle d'Aubigné score. The relationships between Walid's classification and radiological or functional outcomes were analyzed. RESULTS: According to Walid's classification, 18, 13, 6 were classified as QLP1, QLP2 and QLP3, respectively. The average follow-up was 35.5 ± 10.7 months. We obtained anatomic reduction in 48.6 % (18/37) of cases, imperfect reduction in 40.5 % (15/37) of cases, and poor reduction in 10.8 % (4/37) of cases. Excellent-good functional scores were found in 83.7 % (modified Merle d'Aubigné). There were no cases of screw entering the hip, pull-out and loosening or implant failure during the follow-up. Walid's classification was positively correlated with radiological outcomes of reduction (r = 0.661; P < 0.001), and functional outcomes (r = 0.478; P = 0.003). Unsatisfactory reduction was demonstrated a correlation with the development of post-traumatic arthritis (r =-0.410; P = 0.012). CONCLUSIONS: ORIF may be suggested for quadrilateral plate fractures in the elderly. Walid's classification system is associated with the reduction quality and functional recovery.

Using arthroscopy combined with fluoroscopic technique for accurate location of the bone tunnel entrance in chronic ankle instability treatment.

BACKGROUND: Minimally invasive reconstruction techniques are used for anatomical ligament construction of the lateral collateral ligament complex of the ankle, but the two key elements, the bone tunnel and the appropriate graft tension, for the identification of the anatomic location during the surgery are not clearly stated. METHODS: The patients with chronic ankle instability who received arthroscopic anatomic lateral ligament complex reconstruction were retrospectively analyzed. The anatomical location of the bone tunnel was performed under arthroscopy combined with fluoroscopy for accurate location of the bone tunnel entrance. The graft tension and routing were controlled under arthroscopic visualization. The clinical outcomes were assessed using the Karlsson-Peterson score, Sefton articular stability scale, and Visual Analogue Scale (VAS). The complications were recorded during the follow-up. RESULTS: A total of 18 patients were enrolled in this study. The mean follow-up was 33.33 ± 3.69 (range from 24 to 36) months. No patient had recurrence of ankle instability after the operation. According to the Sefton articular stability scale, 94.5% of the patients had excellent/good function. The mean value of the anterior drawer tests and the talar tilt angle examination were decreased. The mean of the Karlsson-Peterson score and the Visual Analogue Scale(VAS) score were both improved significantly. CONCLUSIONS: The anatomic reconstruction of the ankle lateral ligament complex to treat chronic ankle instability using the arthroscopy combined with the fluoroscopic technique could improve the clinical functions, satisfaction, and reduced pain of patients.

Endoscopic "internal splinting" repair technique for acute Achilles tendon rupture.

INTRODUCTION: Recently, endoscopically assisted Achilles tendon repair techniques have improved to overcome the surgical complications. However, the risk of sural nerve injury and the strength of repair are still the most concerning aspects. MATERIAL AND METHODS: Twenty three patients with acute Achilles tendon rupture were reviewed in the present study. We stitch the Achilles tendon above the ruptured site using the endoscopic locking loop suture technique, and the knotless anchor suture-bridge technique can be used to make the distal fixation of threads. The function was assessed using the muscle power (MRC0-5), ATRS scores, AOFAS ankle-hindfoot scores, and VAS scores at the final follow-up. RESULTS: The mean follow-up time was 15.74 ± 2.43 months (12-18). At the final follow-up, the average of the muscle power (MRC0-5), ATRS score, AOFAS ankle-hindfoot score, and VAS score are 4.74 ± 0.45, 97.83 ± 2.77, 96.52 ± 4.87, and 0.35 ± 0.49, respectively. Every patient returned to previous sports activity at 6 months postoperative. No wound infection and sural nerve injuries were encountered. Only one case suffers local irritation at the medial knotless anchor site. CONCLUSIONS: Endoscopic "internal splinting" repair for acute Achilles tendon rupture using locking loop stitch with suture-bridge technique leads to an expedited return to activity with a low risk of complications. LEVEL OF EVIDENCE: Level IV, case series.

MicroRNA-532-5p is implicated in the regulation of osteoporosis by forkhead box O1 and osteoblast differentiation.

BACKGROUND: MicroRNAs (miRNAs) are critical regulators in osteogenesis and cartilage formation. This study was designed to investigate whether miR-532-5p plays a role in the regulation of osteoporosis. METHODS: Osteoporotic fractures (OP group, n = 10) or osteoarthritis without osteoporosis (control group, n = 10) were selected as subjects in this study. Quantitative analysis of gene expression was performed by RT-PCR. Western blot was used to determine the expression levels of protein forkhead O1 (FOXO1). Bioinformatics analyses and luciferase reporter assay were used to verify the downstream target of miR-532-5p. RESULTS: Compared with the non-osteoporotic controls, miR-532-5p was upregulated in osteoporotic samples, and expression of miR-532-5p was downregulated in the osteogenic C2C12 cell model. Overexpression of miR-532-5p resulted in decreased expression levels of key osteoblast markers, including alkaline phosphatase (ALP), osteocalcin (OC), and collagen type I alpha 1 (COL1A1). The inhibitory results of miR-532-5p were reversed. MiR-532-5p contained a putative FOXO1 binding site. Moreover, miR-532-5p inhibited the expression of FOXO1, and overexpression of FOXO1 inhibited the effect of miR-532-5p on osteoblast markers. CONCLUSIONS: MiR-532-5p can provide references to osteoporosis by regulating the expression of FOXO1 and osteoblast differentiation. MiR-532-5p might serve as a therapeutic target for osteoporosis.

All-Inside Arthroscopic Anterior Talofibular Ligament Anatomic Reconstruction With a Gracilis Tendon Autograft for Chronic Ankle Instability in High-Demand Patients.

The goal of this study was to evaluate the surgical technique and clinical outcome of all-inside arthroscopic anterior talofibular ligament anatomic reconstruction with a gracilis tendon autograft for chronic ankle instability in high-demand patients. Fifteen consecutive patients (14 [93.3%] males and 1 [6.7%] female, mean age 31.9 ± 7.8 [range 21 to 48] years) with chronic ankle instability were enrolled in this study. Under direct arthroscopic visualization, bone tunnels were created in the fibula and talus by a 4.5-mm cannulated drill system. The gracilis tendon autograft was passed through the tunnels and secured by 5.0-mm interference screws. At the final follow-up, functional evaluation was carried out according to the Ankle-Hindfoot Score by the American Orthopaedic Foot and Ankle Society, Sefton grading system, and visual analog scale score. Complications were also recorded. Mean follow-up was 19.5 ± 1.8 (range 18 to 24) months. No complications of wound infection and nerve injury were noted. No patients experienced recurrent ankle instability. Radiologically, the mean varus tilting angle was 15.2° ± 1.5° before surgery and 4.3° ± 1.2° at the last follow-up (p ≤ .001). The anterior drawer distance was 13.2 ± 1.5 mm before surgery and 4.8 ± 1.1 mm at last follow-up (p ≤ .001). The mean American Orthopaedic Foot and Ankle Society and visual analog scale scores were 56.8 ± 10.5 and 5.7 ± 1.3 before surgery, which became 90.2 ± 6.2 and 0.5 ± 0.8 after surgery. Fourteen (93.3%) patients reported excellent/good functional results according to the Sefton grading system (6 [40.0%] excellent, 8 [53.3%] good, and 1 [6.7%] fair). From our clinical experience, all-inside arthroscopic anterior talofibular ligament anatomic reconstruction with a gracilis tendon is an effective treatment for chronic ankle instability in high-demand patients.

The effects of sclerostin antibody plus parathyroid hormone (1-34) on bone formation in ovariectomized rats.

Previous studies have demonstrated the effects of sclerostin antibody (Scl-Ab) and parathyroid hormone (1-34, PTH) on healing in osteoporosis; however, reports about the combined effects of Scl-Ab plus PTH on osteoporosis are limited. This study was designed to investigate the impact of combined treatment with Scl-Ab and PTH on osteoporosis healing in ovariectomized (OVX) rats. After bilateral ovariectomy, 12 weeks were allowed to pass for the establishment of standard conditions for osteoporosis in animal models. The rats then randomly received a vehicle (control), Scl-Ab (25 mg/kg body weight, twice weekly), PTH (60 µg/kg, three times per week) or PTH plus Scl-Ab until death at 12 weeks. The blood and distal femurs of the rats were harvested for evaluation. The results of treatment for osteoporosis were evaluated by serum analysis, histology, microcomputed tomography (micro-CT) and biomechanical tests. Results from this study indicated that PTH + Scl-Ab had stronger effects on the prevention and treatment of osteoporosis than either of the monotherapies in OVX rats. The PTH + Scl-Ab produced the strongest effects on bone volume fraction (BV/TV), bone trabecular thickness (Tb.Th), trabecular number (Tb.N) and trabecular spacing (Tb.Sp), bone mineral density (BMD) and strength of distal femurs and increased the levels of procollagen type I N­terminal propeptide (PINP) and osteocalcin. In contrast, monotherapy with PTH or Scl-Ab showed no differences between treated groups in the assessment of the metaphysis of contralateral femurs by histology, serum, biomechanical tests and micro-CT. These results seem to indicate that Scl-Ab plus PTH has an additive effect on osteoporosis in OVX rats.

p63 protects chondrosarcoma malignancies mainly by enhancing the expression of PTEN.

Abnormal expression of p63 has been well identified in multiple malignancies. However, little study has been done on the association between p63 and chondro sarcoma. In the current study, we mainly explored the expression of p63 in different grades of chondrosarcoma. Our data showed that p63 was significantly decreased in grade II and III chondrosarcoma compared with that of grade I chondrosarcoma and normal control. As the characteristic of grade II and III chondrosarcoma is metastasis, we then searched the function of p63 chondrosarcoma. In vitro study showed that overexpression of p63 significantly suppressed chondrosarcoma cell viability, migration and invasion. Meanwhile, upregualtion of p63 induced chondrosarcoma cell apoptosis. Furthermore, we showed that overexpression of p63 could significantly increase the protein expression of PTEN. In contrast, silencing of PTEN markedly reduced the protein levels of Bax, and enhanced the expression of PCNA and p27, even in cells transfected with p-p63. These data showed that p63 was a tumor suppressor mainly through regulating PTEN in chondrosarcoma cells. In summary, reduction of p63 in grade II and III chondrosarcoma enhances the malignant phenotype mainly through modulating the expression of PTEN.

Biomechanical comparison of a novel transoral atlantoaxial anchored cage with established fixation technique - a finite element analysis.

BACKGROUND: The transoral atlantoaxial reduction plate (TARP) fixation has been introduced to achieve reduction, decompression, fixation and fusion of C1-C2 through a transoral-only approach. However, it may also be associated with potential disadvantages, including dysphagia and load shielding of the bone graft. To prevent potential disadvantages related to TARP fixation, a novel transoral atlantoaxial fusion cage with integrated plate (Cage + Plate) device for stabilization of the C1-C2 segment is designed. The aims of the present study were to compare the biomechanical differences between Cage + Plate device and Cage + TARP device for the treatment of basilar invagination (BI) with irreducible atlantoaxial dislocation (IAAD). METHODS: A detailed, nonlinear finite element model (FEM) of the intact upper cervical spine had been developed and validated. Then a FEM of an unstable BI model treated with Cage + Plate fixation, was compared to that with Cage + TARP fixation. All models were subjected to vertical load with pure moments in flexion, extension, lateral bending and axial rotation. Range of motion (ROM) of C1-C2 segment and maximum von Mises Stress of the C2 endplate and bone graft were quantified for the two devices. RESULTS: Both devices significantly reduced ROM compared with the intact state. In comparison with the Cage + Plate model, the Cage + TARP model reduced the ROM by 82.5 %, 46.2 %, 10.0 % and 74.3 % in flexion, extension, lateral bending, and axial rotation. The Cage + Plate model showed a higher increase stresses on C2 endplate and bone graft than the Cage + TARP model in all motions. CONCLUSIONS: Our results indicate that the novel Cage + Plate device may provide lower biomechanical stability than the Cage + TARP device in flexion, extension, and axial rotation, however, it may reduce stress shielding of the bone graft for successful fusion and minimize the risk of postoperative dysphagia. Clinical trials are now required to validate the reproducibility and advantages of our findings using this anchored cage for the treatment of BI with IAAD.

[Three-dimensional Finite Element Analysis to T-shaped Fracture of Pelvis in Sitting Position].

We developed a three-dimensional finite element model of the pelvis. According to Letournel methods, we established a pelvis model of T-shaped fracture with its three different fixation systems, i. e. double column reconstruction plates, anterior column plate combined with posterior column screws and anterior column plate combined with quadrilateral area screws. It was found that the pelvic model was effective and could be used to simulate the mechanical behavior of the pelvis. Three fixation systems had great therapeutic effect on the T-shaped fracture. All fixation systems could increase the stiffness of the model, decrease the stress concentration level and decrease the displacement difference along the fracture line. The quadrilateral area screws, which were drilled into cortical bone, could generate beneficial effect on the T-type fracture. Therefore, the third fixation system mentioned above (i. e. the anterior column plate combined with quadrilateral area screws) has the best biomechanical stability to the T-type fracture.

Tendon derived stem cells promote platelet-rich plasma healing in collagenase-induced rat achilles tendinopathy.

BACKGROUND/AIMS: Tendon injuries are common, difficult to cure and usually healed with fibrosis and scar tissue. The aim of this study was to evaluate tendon derived stem cells (TDSCs) and platelet rich plasma (PRP) in the treatment of collagenase induced Achilles tendinopathy in rat. METHODS: Four and 8 weeks (n=18) after TDSCs, PRP, PRP with TDSC or PBS (control) injection into collagenase or saline (sham) injected rat Achilles tendon, tendon tissue was harvested and tendon quality was evaluated by histology and biomechanical testing. TDSCs were cultured and treated by 10% PRP, and the FAK/ERK1/2 signaling pathway and tenocyte-related genes were detected by western blot analysis. RESULTS: Compared to the control, PRP treatment resulted in better healing of injured tendons with improved histological outcomes and biomechanical functions. The addition of TDSCs to PRP treatment significantly enhanced the effects of PRP treatment alone. TDSC injection alone had little effect on tendon healing. PRP and PRP with TDSC treatments of collagenase induced tendon injuries also increased the mRNA and protein expression of tenocyte-related genes (type I collagen, SCX, Tenascin C) and activated the focal adhesion kinase (FAK) and extracellular-regulated kinase (ERK) 1/2 signaling pathways. Treatment of TDSCs in vitro with 10% PRP significantly increased the phosphorylation levels of FAK and ERK1/2 and the protein levels of tenocyte-related genes (Col I, SCX and Tenascin C). Inhibition of the FAK and ERK1/2 signaling pathways abolished the effect of PRP. CONCLUSION: This study concludes that PRP combined with TDSCs is potentially effective for the treatment of tendinopathy. The PRP induced, FAK and ERK1/2 dependent activation of tenocyte related genes in TDSCs in vitro suggests that the beneficial healing effect of the PRP with TDSC combination might occur by means of an improved TDSC differentiation toward the tenocyte lineage. Thus, a PRP with TDSC combination therapy may be clinically useful.

Tendon stem cells seeded on dynamic chondroitin sulfate and chitosan hydrogel scaffold with BMP2 enhance tendon-to-bone healing.

Failure to adequately reconstruct the tendon-to-bone interface constitutes the primary etiology underlying rotator cuff retear after surgery. The purpose of this study is to construct a dynamic chondroitin sulfate and chitosan hydrogel scaffold (CHS) with bone morphogenetic protein 2 (BMP2), then seed tendon stem cells (TSCs) on BMP2-CHS for the rotator cuff reconstruction of tendon-to-bone interface. In this dynamic hydrogel system, the scaffold could not only have good biocompatibility and degradability but also significantly promote the proliferation and differentiation of TSCs. The ability of BMP2-CHS combined with TSCs to promote regeneration of tendon-to-bone interface was further verified in the rabbit rotator cuff tear model. The results showed that BMP2-CHS combined with TSCs could induce considerable collagen, fibrocartilage, and bone arrangement and growth at the tendon-to-bone interface and promote the biomechanical properties. Overall, TSCs seeded on CHS with BMP2 can enhance tendon-to-bone healing and provide a new possibility for improving the poor prognosis of rotator cuff surgery.

Anterior atlantoaxial motion preservation fixation technique for axis complex fractures (odontoid process with Hangman's fractures) and technique notes.

This study aims to investigate the feasibility and efficacy of anterior atlantoaxial motion preservation fixation (AMPF) in treating axis complex fractures involving the odontoid process fracture and Hangman's fractures with C2/3 instability. A retrospective study was conducted on eight patients who underwent AMPF for axis complex fractures at the General Hospital of Central Theater Command from February 2004 to October 2021. The types of axis injuries, reasons for injuries, surgery time, intraoperative blood loss, spinal cord injury classification (American Spinal Injury Association, ASIA), as well as complications and technical notes, were documented. This study included eight cases of type II Hangman's fracture, five cases of type II and three cases of type III odontoid process fracture. Five patients experienced traffic accidents, while three patients experienced falling injuries. All patients underwent AMPF surgery with an average intraoperative blood loss of 288.75 mL and a duration of 174.5 min. Two patients experienced dysphagia 1 month after surgery. The patients were followed up for an average of 15.63 months. One case improved from C to E in terms of neurological condition, three cases improved from D to E, and four cases remained at E. Bony fusion and Atlantoaxial Motion Preservation were successfully achieved for all eight patients. AMPF is a feasible and effective way for simultaneous odontoid process fracture and Hangman's fractures with C2/3 instability, while preserving atlantoaxial movement.

Evaluation of biomechanical properties of anterior atlantoaxial transarticular locking plate system using three-dimensional finite element analysis.

PURPOSE: To evaluate a new anterior atlantoaxial transarticular locking plate system using finite element analysis. METHODS: Thin-section spiral computed tomography was performed from occiput to C2 region. A finite element model of an unstable atlantoaxial joint, treated with an anterior atlantoaxial transarticular locking plate system, was compared with the simple anterior atlantoaxial transarticular screw system. Flexion, extension, lateral bending, and axial rotation were imposed on the model. Displacement of the atlantoaxial transarticular screw and stress at the screw-bone interface were observed for the two internal fixation systems. RESULTS: Screw displacement was less using the anterior atlantoaxial transarticular locking plate system compared to simple anterior atlantoaxial transarticular screw fixation under various conditions, and stability increased especially during flexion and extension. CONCLUSIONS: The anterior atlantoaxial transarticular locking plate system not only provided stronger fixation, but also decreased screw-bearing stress and screw-bone interface stress compared to simple anterior atlantoaxial transarticular screw fixation.

Dog tibial nerve regeneration across a 30-mm defect bridged by a PRGD/PDLLA/ß-TCP/NGF sustained-release conduit.

Nerve conduits have emerged as alternatives to autologous nerve grafts, but their use in large-diameter, critical nerve repairs is limited. In the previous study, we prepared a PRGD/PDLLA/ß-TCP/NGF sustained-release nerve conduit, which was made of RGD peptide modified poly{(lactic acid)-co-[(glycolic acid)-alt-(L-lysine)]} (PRGD), poly(d,l-lactic acid) (PDLLA), ß-tricalcium phosphate (ß-TCP) and nerve growth factor (NGF). Here we attempted to use the PRGD/PDLLA/ß-TCP/NGF sustained-release nerve conduit to bridge a 30-mm dog tibial nerve defect in six beagles. The other beagles were divided into group autograft (n = 6) as positive control and group PDLLA (n = 6) as negative control. After 9 months of implantation, nerve conduction velocities, the density of myelinated fibers, the mean diameter of axon, and the average thickness of myelin sheath in tibial nerves bridged with PRGD/PDLLA/ß-TCP/NGF sustained-release nerve conduits were similar to those treated with autologous nerve (p > 0.05). Neither electrophysiological nor histological restoration was obtained in group PDLLA. Evidence is thus provided in support of the use of PRGD/PDLLA/ß-TCP/NGF sustained-release nerve conduits as alternatives to autologous nerve grafts for treatment of large-diameter, critical defects in peripheral nerves.