Study DesignMechanical study.PurposeTo compare the pullout strength of different screw designs and augmentation techniques in an osteoporotic bone model.Overview of LiteratureAdequate bone screw pullout strength is a common problem among osteoporotic patients. Various screw designs and augmentation techniques have been developed to improve the biomechanical characteristics of the bone–screw interface.MethodsPolyurethane blocks were used to mimic human osteoporotic cancellous bone, and six different screw designs were tested. Five standard and expandable screws without augmentation, eight expandable screws with polymethylmethacrylate (PMMA) or calcium phosphate augmentation, and distal cannulated screws with PMMA and calcium phosphate augmentation were tested. Mechanical tests were performed on 10 unused new screws of each group. Screws with or without augmentation were inserted in a block that was held in a fixture frame, and a longitudinal extraction force was applied to the screw head at a loading rate of 5 mm/min. Maximum load was recorded in a load displacement curve.ResultsThe peak pullout force of all tested screws with or without augmentation was significantly greater than that of the standard pedicle screw. The greatest pullout force was observed with 40-mm expandable pedicle screws with four fins and PMMA augmentation. Augmented distal cannulated screws did not have a greater peak pullout force than nonaugmented expandable screws. PMMA augmentation provided a greater peak pullout force than calcium phosphate augmentation.ConclusionsExpandable pedicle screws had greater peak pullout forces than standard pedicle screws and had the advantage of augmentation with either PMMA or calcium phosphate cement. Although calcium phosphate cement is biodegradable, osteoconductive, and nonexothermic, PMMA provided a significantly greater peak pullout force. PMMA-augmented expandable 40-mm four-fin pedicle screws had the greatest peak pullout force.
Intra-articular bupivacaine injection at different stages of the operation yielded variable VAS scores in the postoperative period. Closing the drain after intra-articular injection resulted in an early onset analgesic effect without shortening the duration.
Osteoid osteoma is an uncommon benign tumor and causes severe pain, being worse at night, that responds dramatically to nonsteroidal anti-inflammatory medications. An osteoid osteoma of the patella is very rare and if it arise close to chondral surface differential diagnosis may be challenging. In three patients the osteoid osteoma was completely excised by nidus removal by mosaicoplasty set with open surgical technique. The patients were followed up in average for 31 (16-48 months) months with annual clinical and radiographic evaluations. There were no relapse of the pain and no residual recurrent tumor. The aim of the treatment for osteoid osteoma is to remove entire nidus by open surgical excision or by percutaneous procedures such as percutaneous radiofrequency and laser ablation. Mosaicoplasty is a good alternative for treatment of osteoid osteoma of the patella in the subchondral bone.
Flap surgery has wide use in plastic surgery in the closure of tissue defects. In spite of the major advances in plastic surgery in the past years, flap surgery is still associated with significant mortality. Ischemia-reperfusion (I/R) injury, which is a complex injury associated with flap blood flow, is one of the most important causes of flap failure. The main pathophysiology underneath I/R injury is associated with reactive oxygen species, which can be prevented by certain antioxidant applications. Antioxidants have been widely used in flap surgery and I/R injury previously. There have been a lot of articles showing positive effects of antioxidants on I/R injury. In this chapter, we focus the mechanism of I/R injury and how antioxidants can able to diminish the damage, moreover demonstrating the effect of certain antioxidants on I/R injury that has been investigated previously.
Study DesignProspective analysis of collected data.PurposeWe determine the need for the use of mid-length pedicle screws (screws with 2.5-mm long increments) during posterior spinal instrumentation.Overview of LiteratureMany biomechanical studies have been performed showing that increasing the pedicle screw insertion depth provides an improved resistance to pullout, cyclic loading, and derotational forces, but no intermediate length screws were used.MethodsWe prospectively evaluated 120 patients who received posterior segmental instrumentation for structural scoliosis. Preoperatively, 91.44-cm long cassette anteroposterior (AP), lateral, and AP bending radiographs and multiplanar computed tomography were performed in all patients routinely. We measured chord length to determine the maximum probable screw length of all vertebrae. All pedicle screws were attempted to be placed as long as possible. The main intention was at least to engage the subcortical bone of the anterior vertebral cortex. Especially in the apical region, the screws were attempted to be inserted bicortically. The length, level, region, and side of each screw were recorded. Screws with 5-mm increments were called standard length screws (SLS), and middle-sized screws with 2.5-mm increments were called mid-length screws (MLS).ResultsOf 2,846 pedicle screws inserted, 1,575 (55.4%) were SLS and 1,271 (44.6%) were MLS, demonstrating a need for MLS in scoliosis surgery (p<0.05). The need for MLS increased significantly in the thoracic region, apical vertebrae, and convex side (p<0.05).ConclusionsIf anterior cortex engagement or longer placement of pedicle screws is intended during scoliosis surgery, for safer placement, screws with 2.5-mm increments should be available in posterior instrumentation systems.
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