Evaluation of the horizontal approach to the medial malleolar facet in sagittal talar fractures through dorsiflexion and plantarflexion positions.

BACKGROUND: Talar fractures often require osteotomy during surgery to achieve reduction and screw fixation of the fractured fragments due to limited visualization and operating space of the talar articular surface. The objective of this study was to evaluate the horizontal approach to the medial malleolus facet by maximizing exposure through dorsiflexion and plantarflexion positions. METHODS: In dorsiflexion, plantarflexion, and functional foot positions, we respectively obtained the anterior and posterior edge lines of the projection of the medial malleolus on the medial malleolar facet. The talar model from Mimics was imported into Geomagic software for image refinement. Then Solidworks software was used to segment the medial surface of the talus and extend the edge lines from the three positions to project them onto the "semicircular" base for 2D projection. The exposed area in different positions, the percentage of total area it represents, and the anatomic location of the insertion point at the groove between the anteroposternal protrusions of the medial malleolus were calculated. RESULTS: The mean total area of the "semicircular" region on the medial malleolus surface of the talus was 542.10 ± 80.05 mm2. In the functional position, the exposed mean area of the medial malleolar facet around the medial malleolus both anteriorly and posteriorly was 141.22 ± 24.34 mm2, 167.58 ± 22.36mm2, respectively. In dorsiflexion, the mean area of the posterior aspect of the medial malleolar facet was 366.28 ± 48.12 mm2. In plantarflexion, the mean of the anterior aspect of the medial malleolar facet was 222.70 ± 35.32 mm2. The mean overlap area of unexposed area in both dorsiflexion and plantarflexion was 23.32 ± 5.94 mm2. The mean percentage of the increased exposure area in dorsiflexion and plantarflexion were 36.71 ± 3.25% and 15.13 ± 2.83%. The mean distance from the insertion point to the top of the talar dome was 10.69 ± 1.24 mm, to the medial malleolus facet border of the talar trochlea was 5.61 ± 0.96 mm, and to the tuberosity of the posterior tibiotalar portion of the deltoid ligament complex was 4.53 ± 0.64 mm. CONCLUSIONS: Within the 3D model, we measured the exposed area of the medial malleolus facet in different positions and the anatomic location of the insertion point at the medial malleolus groove. When the foot is in plantarflexion or dorsiflexion, a sufficiently large area and operating space can be exposed during surgery. The data regarding the exposed visualization area and virtual screws need to be combined with clinical experience for safer reduction and fixation of fracture fragments. Further validation of its intraoperative feasibility will require additional clinical research.

3D simulation of percutaneous sustentaculum tali screw insertion in calcaneal fractures.

BACKGROUND: In calcaneal fractures, the percutaneous screw fixation (PSF) is currently considered to be the better choice, but it is difficult to accurately place the screw into the sustentaculum tali (ST) during the operation. In this study, the ideal entry point, angle, diameter and length of the screw were calculated by simulating the operation process. METHODS: We retrospectively collected the calcaneus computed tomography (CT) scans of 180 adults, DICOM-formatted CT-scan images of each patient were imported into Mimics software to establish calcaneus model. Virtual screws were placed on the lateral of the posterior talar articular surface (PTAS), the lateral edge of the anterior process of calcaneus (APC), and the calcaneal tuberosity, respectively, the trajectory and size of the screws were calculated. RESULTS: The mean maximum diameter of the PTAS screw was 42.20 ± 3.71 mm. The vertical distance between the midpoint of the APC optimal screw trajectory and the lowest point of the tarsal sinus was 10.67 ± 1.84 mm, and the distance between the midpoint of the APC optimal screw trajectory and the calcaneocuboid joint was 5 mm ~ 19.81 ± 2.08 mm. The mean maximum lengths of APC screws was 44.69 ± 4.81 mm, and the Angle between the screw and the coronal plane of the calcaneus from proximal to distal was 4.72°±2.15° to 20.52°±3.77°. The optimal point of the maximum diameter of the calcaneal tuberosity screw was located at the lateral border of the achilles tendon endpoint. The mean maximum diameters of calcaneal tuberosity screws was 4.46 ± 0.85 mm, the mean maximum lengths of screws was 65.31 ± 4.76 mm. We found gender-dependent differences for the mean maximum diameter and the maximum length of the three screws. CONCLUSIONS: The study provides effective positioning for percutaneous screw fixation of calcaneal fractures. For safer and more efficient screw placement, we suggest individualised preoperative 3D reconstruction simulations. Further biomechanical studies are needed to verify the function of the screw.

Pipkin type III femoral head fracture-dislocation combined with complicated acetabular fracture: A rare case report and literature review.

RATIONALE: Pipkin III fracture, which is characterized by high risk of avascular necrosis of the femoral head, is extremely rare. It is more difficult to treat and has a worse prognosis when accompanied with severe acetabular fractures. Few studies show that both Pipkin type III femoral head fracture-dislocation and complicated acetabular fracture presented in one patient. PATIENT CONCERNS: A 34-year-old male suffered a terrible traffic accident with a serious damage to the left side when he was sitting in the car's cockpit. Pelvic radiograph and 3-dimensional reconstruction of computed tomography revealed characteristics of fractures before the emergency operation. DIAGNOSIS: Pipkin III fractures combined with complicated acetabular fracture. INTERVENTIONS: Firstly, we used combined anterior and posterior approach for treatment to fix the femoral head fractures. Then, we completed anatomical reduction of fractures with countersunk head screw, hollow screw, and reconstruction plate. OUTCOMES: At the 12-months follow-up, the patient could walk freely and perform activities of daily living without necrosis of femoral head and heterotopic ossification. LESSONS: Although there are serious complications in Pipkin III fractures combined with complicated acetabular fracture, early surgical treatment with appropriate approach and fixation could get satisfactory results.

Substance P Promotes the Proliferation, but Inhibits Differentiation and Mineralization of Osteoblasts from Rats with Spinal Cord Injury via RANKL/OPG System.

Spinal cord injury (SCI) causes a significant amount of bone loss, which results in osteoporosis (OP). The neuropeptide substance P (SP) and SP receptors may play important roles in the pathogenesis of OP after SCI. To identify the roles of SP in the bone marrow mesenchymal stem cell derived osteoblasts (BMSC-OB) in SCI rats, we investigated the expression of neurokinin-1 receptors (NK1R) in BMSC-OB and the effects of SP on bone formation by development of BMSC-OB cultures. Sixty young male Sprague-Dawley rats were randomized into two groups: SHAM and SCI. The expression of NK1R protein in BMSC-OB was observed using immunohistochemistry and Western blot analysis. The dose- and time-dependent effects of SP on the proliferation, differentiation and mineralization of BMSC-OB and the expression of osteoblastic markers by in vitro experiments. The expression of NK1R in BMSC-OB was observed on plasma membranes and in cytoplasm. One week after osteogenic differentiation, the expression of NK1R was significantly increased after SCI at mRNA and protein levels. However, this difference was gradually attenuated at 2 or 3 weeks later. SP have the function to enhance cell proliferation, inhibite cell differentiation and mineralization at a proper concentration and incubation time, and this effect would be inhibited by adding SP or NK1R antagonist. The expression of RANKL/OPG was significantly increased in tibiae after SCI. Similarly, the RANKL/OPG expression in SCI rats was significantly increased when treating with 10-8 M SP. SP plays a very important role in the pathogenesis of OP after SCI. The direct effect of SP may lead to increased bone resorption through the RANKL/OPG axis after SCI. In addition, high expression of SP also results in the suppression of osteogenesis in SCI rats. Then, the balance between bone resorption and bone formation was broken and finally osteoporosis occurred.