Local Bone Necrosis Research Articles

Optimal parameters to avoid thermal necrosis during bone drilling: A finite element analysis.

The drilling bone may potentially cause excessive frictional heat, which can lead to local bone necrosis. This heat generation and local necrosis has been suggested to contribute to the resorption of bone around the placed screws, ending in loss of screw purchase in the bone and inadvertent loosening and/or the bone-implant construct. In vivo studies on this subject have inherent obstacles not the least of which is controlling the variables and real time bone temperature data acquisition. Theoretical models can be generated using computer software and the inclusion of known constants for the mechanical properties of metal and bone. These known Data points for the variables (drill bit and bone) enables finite element analysis of various bone drilling scenarios. An elastic-plastic three-dimensional (3D) acetabular bone mode was developed and finite element model analysis (FEA) was applied to various simulated drilling procedures. The FEA results clearly indicate that the depth of drilling and the drill speed both have a significant effect on the temperature during drilling procedures. The reduction of the feeding speed leads to a reduction in bone temperature. Our data suggests that reducing the feeding speed regardless of RPMs and pressure applied could be a simple useful and effective way to reduce drilling temperatures. This study is the first step in helping any surgeon who drills bone and places screws to better understand the ideal pressure to apply and drill speed to employ and advance rate to avoid osteonecrosis. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2386-2391, 2017.

Percutaneous Magnetic Resonance Imaging–Guided Bone Tumor Management and Magnetic Resonance Imaging–Guided Bone Therapy

Magnetic resonance imaging (MRI) is promising tool for image-guided therapy. In musculoskeletal setting, image-guided therapy is used to direct diagnostic and therapeutic procedures and to steer patient management. Studies have demonstrated that MRI-guided interventions involving bone, soft tissue, joints, and intervertebral disks are safe and in selected indications can be the preferred action to manage clinical situation. Often, these procedures are technically similar to those performed in other modalities (computed tomography, fluoroscopy) for bone and soft tissue lesions. However, the procedural perception to the operator can be very different to other modalities because of the vastly increased data.Magnetic resonance imaging guidance is particularly advantageous should the lesion not be visible by other modalities, for selective lesion targeting, intra-articular locations, cyst aspiration, and locations adjacent to surgical hardware. Palliative tumor-related pain management such as ablation therapy forms a subset of procedures that are frequently performed under MRI. Another suitable entity for MRI guidance are the therapeutic percutaneous osseous or joint-related benign or reactive conditions such as osteoid osteoma, epiphyseal bone bridging, osteochondritis dissecans, bone cysts, localized bone necrosis, and posttraumatic lesions. In this article, we will describe in detail the technical aspects of performing MRI-guided therapeutic musculoskeletal procedures as well as the clinical indications.

Osteotomy Irrigation: Is it Necessary?

Surgical placement of dental implants requires an osteotomy. There is suspicion that osseous drilling may generate detrimental heat in the site that may cause localized bone necrosis and, subsequently, failure of the dental implant to osseointegrate. Cooling aqueous irrigation has been advocated to prevent such overheating. However, irrigation can interfere with operator vision and precludes bone shaving collection from the drill flukes for use in autogenous grafting. Small diameter drills may generate more heat than larger diameter drills and may need to be irrigated when smaller diameter implants are to be placed in dense bone. Contemporary larger diameter drills may not generate detrimental heat and may incrementally remove any heat damaged bone from the previous drilling. It may be safe not to use irrigation for less bone dense sites when larger diameter drills are used. In addition, higher drill force and speed may minimize osseous heating by minimizing the time of in-bone drill operation and heat generation. Irrigation to prevent bone heating during the osteotomy may not be necessary when using contemporary drill designs with an expeditious drilling technique.

Intramedullary pressure during endoscopy of the long bone: Experimental results of a new endoscopic technique

This study shows the local changes in intramedullary pressure during a new endoscopic technique for the medullary canal of the long bone. The procedure of intramedullary bone endoscopy (IBE) was performed on 4 tibial amputations. By slowly pushing the endoscope distally under visual control and endoscopic preparation of the medullary canal, a “neocavum” for endoscopy was created. During the procedure, the intramedullary pressure was continuously measured: Highest peak pressure was 125 mm Hg. We therefore conclude that the procedure of IBE is a safe intervention within the medullary canal of the long bone. Local or systemic side effects, common to intramedullary reaming in fracture treatment (fat-embolism, local bone necrosis, reduction in cortical blood flow) should not be expected.

Endoscopy of the Calcaneal Bursa in Horses

To describe endoscopic approaches to the calcaneal bursa and clinical findings in 2 horses with calcaneal bursitis. Cadaver evaluations and retrospective case reports. 12 cadavers and 2 adult horses. Cadaver specimens of the calcaneal bursa were evaluated with a rigid arthroscope and gross dissection to determine the endoscopic appearance of anatomic structures located within the bursa. The site(s) for placement of the arthroscope and instrument(s) was determined based on cadaver dissection and endoscopic examination. Placement of the arthroscope 1 cm dorsal to the superficial digital flexor tendon (SDFT) and 1 cm distal to the medial or lateral aspect of the SDFT retinaculum allowed consistent examination of the tuber calcis, proximal aspect of the long plantar ligament, calcaneal tendon of the gastrocnemius muscle inserting on the tuber calcis, SDFT and the proximal and distal extent of the bursa. Lesions observed and treated with use of endoscopy included local bone necrosis of the proximoplantar aspect of the tuber calcis and damage of the origin of the long plantar ligament in one horse. Mild disruption of the superficial digital flexor tendon and long plantar ligament were observed and debrided in another horse. Endoscopic exploration of the calcaneal bursa is clinically feasible to treat infectious and noninfectious bursitis and to help identify the cause(s) of undiagnosed bursitis or lameness associated with the calcaneus, superficial digital flexor tendon, tendon of the gastrocnemius muscle, and the long plantar ligament. An endoscopic approach to the calcaneal bursa is recommended whenever possible to decrease complications associated with surgery in this region and improve the diagnosis of infectious and non-infectious calcaneal bursitis.

Biomechanics of healed experimental fractures

Biomechanical properties of osteotomies and physiologically fractured canine femurs fixed with six-hole stainless steel AO/DCP plates (Synthes: Paoli, PA) were investigated with torsional loading 12 weeks postoperatively and were compared. Biomechanical evaluation of fracture healing with compression plate fixation requires a well controlled fracture creation technique which should reflect closely the natural process. Osteotomy has been suspected of creating ;local bone necrosis, a segmental defect, and subsequent healing patterns which do not mimic those following a more physiologic fracture. Two fracture techniques were compared in the mid-diaphyseal canine femur. An osteotomy was created in one limb and stabilized with a dynamic compression plate, while the contralateral limb was fractured physiologically utilizing four-point bending (modified technique of Ashhurst et al.) and also stabilized with a dynamic compression plate. Comminution developed in one animal during the four-point bending fracture creation technique and nonunion developed in an animal following osteotomy. Following sacrifice at three months, dynamic torsion testing demonstrated no statistical difference in mean torque to failure (osteotomy = 27.7, SD 9.4 N m; physiologic fracture = 28.4, SD 5.0 N m). Stiffness, rotation to failure, and energy to failure were also analysed and demonstrated no statistical difference.

Necrotizing (“Malignant”) External Otitis Histopathologic Processes

The histologic findings in a serially sectioned temporal bone, from a patient who succumbed to brain abscess secondary to necrotizing ("malignant") external otitis, are described. The mechanism of invasion of the ear canal appears to be due to local bone necrosis. This in turn extends to the submucosal vasculature of the pneumatic spaces. The infective process extends submucosally, establishing one or several sites of bone destruction. The lumen of the pneumatic space is not involved. In this process, the periphery of the fibrous inflammatory tissue formation is the site of active bone destruction. In pneumococcal petrositis, the peripheral fibrous elements are protective. The process in malignant external otitis may extend directly to adjacent central nervous system structures inoculating the structure with Pseudomonas. Development of Pseudomonas brain abscesses can be slow, allowing for new bone closure of the site from which the infection spreads as demonstrated in this specimen. Therefore, apparent local control of the disease can be established while a central infective process progresses.

INFLUENCE OF ULTRASOUND ON BONE MINERAL METABOLISM.

THE problem of possible noxious effects of ultrasonic energy on calcified tissues is important because of its wide use in clinical and dental practice. The conditions of transmitting the ultrasound to bones and teeth and their surroundings are more complex than in soft tissues, being in a certain sense similar to those resulting from absorption of roentgen radiations in bones, causing, for example, selective overheating of bones due to increased absorption of ultrasonic energy and various interface effects on their surface. Coarsening of trabecular bone pattern, periosteal new-bone formation, circumscribed foci of bone sclerosis, localized bone necrosis, pseudocystic and cystic appearances and bone fractures were observed in various experiments on animals1,2. Not only were damaging effects on bone noted, but also on the dental germs after 3–4 W/cm2 ultrasonic energy9. The traumatic capacity of ultrasound in dentistry became the object of intense investigations from the middle 1960's because of the still wider use of ultrasonic dental cutting instruments in practice. Enamel defects and dyscrasias, loss of tooth structures, pink or yellow discolorations, mobile and fractured teeth and missing teeth were often correlated with the intensity and exposure time3,8. Thus, it can be concluded that there exists a real danger in application of ultrasound of too high an intensity and of prolonged exposure time.

Local and Remote Sequelæ of Infection in the Parodontal Sulcus

(1) It is shown in this paper that the infecting organisms in the parodontal sulcus are confined to the surface, but may be forced into the blood and lymph stream by traumatic interference.2. Local and general disturbances may therefore arise both as a result of the absorption of soluble toxic matter from the pocket into the tissues and also as a result of this traumatic introduction of organisms into the blood-stream.3. The effect of toxic absorption on the local tissues is destruction of the attachment of the tooth-pyorrhoea.4. The remote effects of toxic absorption may be a similar destruction of the connective tissue generally-arthritis and fibrositis. The liver and kidney may suffer since they excrete the toxic matter, and other susceptible tissues may also be involved.5. Traumatic bacteraemia may produce local bone necrosis or "dry" socket. Acute suppurative lymphangitis produces the "pyorrhoetic abscess".6. The remote effect of bacteraemia may be to produce osteomyelitis (e.g. of the tibia) or to convert a simple endocarditis into the bacterial type.7. The mechanism of bone absorption and deposition in response to irritation is discussed.8. Methods of eliminating parodontal infection are referred to and the importance of complete elimination is stressed. It is shown to be not incompatible with the conservation of the teeth.