Computer aided analysis of biomechanical performance of schanz screw with different additive manufacturing materials used in pertrochanteric fixator on an intertrochanteric femoral fracture (corrosion resistance approach).

This study examines the use of computer-aided analysis to evaluate the biomechanical performance of Schanz screws made from different additive manufacturing materials (Ti6Al4V, 316 L, Inconel 625, and Inconel 718) in a pertrochanteric fixator for the treatment of intertrochanteric femoral fractures. Intertrochanteric fractures (ITFs) are severe traumas often seen in the elderly population and can lead to serious consequences. The primary objective of ITF surgery is to provide stability and allow for early ambulation and rehabilitation. The Pertrochanteric Fixator is a surgical implant used to treat hip fractures near the greater trochanter, and is attached to the femur with screws. The procedure is performed under general anesthesia and typically takes 1-2 h. Possible complications include infection, nerve injury, and hardware failure. The aim of this study is to evaluate the biomechanical performance of Schanz screw using computer-aided analysis, comparing the effects of various additive manufacturing materials including Ti6Al4V, 316 L, Inconel 625 and Inconel 718 in a pertrochanteric fixator for intertrochanteric femoral fractures. Additionally, this study will also consider the corrosion resistance of these materials to ensure long-term durability and effectiveness in a clinical setting. The stress values mentioned for the implant materials are as follows. Ti6Al4V: 153.33 MPa, 316 L: 180.98 MPa, Inconel 625: 158.94 MPa, Inconel 718: 148.91 MPa. Higher stress values indicate a greater load transfer to the bone, which can potentially lead to stress shielding. Stress shielding occurs when an implant bears a significant portion of the load that should be transferred to the bone. This reduced stress at the fracture site can prevent the healing process, as bones require adequate stress levels for optimal remodeling and regeneration.

The feasibility of short-segment Schanz screw implanted in an oblique downward direction for the treatment of lumbar 1 burst fracture: a finite element analysis.

BACKGROUND: To evaluate the biomechanical properties of short-segment Schanz screw implanted in an oblique downward direction for the treatment of lumbar 1 burst fracture using a finite element analysis. METHODS: The Universal Spine System (USS) fixation model for adjacent upper and lower vertebrae (T12 and L2) of lumbar 1 vertebra burst fracture was established. During flexion/extension, lateral bending, and rotation, the screw stress and the displacement of bone defect area of the injured vertebrae were evaluated when the downward inserted angle between the long axis of the screws and superior endplate of the adjacent vertebrae was set to 0° (group A), 5° (group B), 10° (group C), and 15°(group D). There were 6 models in each group. RESULTS: There were no significant differences in the maximum screw stress among all the groups during flexion/extension, lateral bending, and rotation (P > 0.05). There were no significant differences in the maximum displacement of the bone defect area of the injured vertebrae among all the groups during flexion/extension, lateral bending, and rotation (P > 0.05). CONCLUSION: Short-segment Schanz screw implanted in an oblique downward direction with different angles (0°/parellel, 5°, 10°, and 15°) did not change the maximum stress of the screws, and there was a lower risk of screw breakage in all groups during flexion/extension, lateral bending, and rotation. In addition, the displacement of the injured vertebra defect area had no significant changes with the change of angles.

Clinical application of a minimally invasive cement-augmentable Schanz screw rod system to treat pelvic ring fractures.

PURPOSE: The purpose of this study is to analyze the results using the USS fracture MIS system (DePuy Synthes) to treat instable pelvic ring fractures. As its outstanding feature, it is the only Schanz screw and rod system at present that combines angular stability, perforation/fenestration of the screws for cement-augmentation, a variable screw length, and a large screw diameter. MATERIALS AND METHODS: Retrospective investigation of 134 pelvic ring fractures treated in 2012-2013. Twenty-five patients obtained the abovementioned implant. Besides baseline characteristics of the included patients and the surgical procedure, a clinical/radiological follow-up of six months was analyzed. RESULTS: Dividing the collective into two groups, I high-energy trauma and II fragility fracture of the pelvis, the following results were recorded: group I: ten patients, six male, age 48.4 ± 19.7 years. Mean ISS 41 ± 22.5, fracture classification: AO/OTA type 61 B1/C1/C3 = 1/5/4. Operative treatment: three transiliac internal fixator, seven iliolumbar fixation, one implant was cement-augmented. Group II: 15 patients, 14 female, age 77.5 ± 10.1 years. Fracture classification according to Rommens: FFPII/III/IV = 6/1/8. Operative treatment: eight transiliac internal fixator, seven iliolumbar fixation, 14 implants were cement-augmented. Overall surgical side complications: 16%. Radiological examination: correct positioning of all ilium screws. Follow-up after six month (16 patients): all showed fracture consolidation. One ilium screw was broken close to the connecting clamp. CONCLUSION: The investigated Schanz screw rod system is a suitable implant to broaden the established procedures to stabilize dorsal pelvic ring fractures. TRIAL REGISTRATION: The study is registered at the Clinical Trial Registry University of Regensburg (Number Z-2017-0878-3).

Open Reduction and Internal Fixation of Posterior Fracture Dislocation of the Shoulder Made Easy!

INTRODUCTION: Posteriorly dislocated humeral head fracture has a great implication, as it is associated with high risk of avascular necrosis, limited access through the deltopectoral approach, and posterior approach to the posteriorly dislocated humeral fracture increases the risk to the remaining blood supply. TECHNICAL TIP: Posteriorly dislocated humeral fracture is approached through deltopectoral approach. Schanz pin is inserted into the humeral head to achieve purchase in the humeral head. Applying laterally directed force the humeral head is disengaged from the lateral margin of glenoid. A rotatory force then repositions the humeral head into a congruous position. Open reduction internal fixation is then carried out in a standard fashion. CONCLUSION: Retrieving the humeral head from the posteriorly dislocated position in patients with posterior fracture dislocation of the shoulder can be challenge to a trauma surgeon. With this novel technique, humeral head is reduced through deltopectoral approach without increasing the risk to the remaining blood supply.

The curative effect of two methods of surgical treatment for thoracolumbar fractures / 重庆医学

Objective To investigate the curative effects of the traditional surgical method of posterior pedicle Schanz screw fixa-tion with partially stripping injured paravertebral muscle in treating thoracolumbar fracture .Methods 52 cases with thoracolumbar fracture underwent posterior pedicle Schanz screw fixation to partially strip injured paravertebral muscle from January ,2010 to Jan-uary ,2012 .The patients were divided into partially stripping injured paravertebral muscle group (32 cases) and traditionally strip-ping injured paravertebral muscle group(20 cases) .The blood loss ,postoperative drainage ,kyphosis postoperative 3 d VAS scores , vertebral height correction rate ,Cobb angle correction ,Oswestry dysfunction indexes were copmared .Results Comparing with tra-ditionally stripping injured paravertebral muscle group ,the partially stripping injured paravertebral muscle group has better effect in transperative blood loss ,postoperative drainage and postoperative 3 d VAS scores ,the differences were statistically significant .But there was no statistical significance between the two groups in vertebral height correction rate ,kyphosis Cobb angle correction ,Os-westry dysfunction indexes .Conclusion Partially strip injured paravertebral muscle has less painful than traditional surgery does , being safe and effective with small invasion and easy to recover .