Wormian bones are abnormal ossicles that develop from extra ossification centers within the cranium. They are most frequently located in the lambdoid suture or the coronal suture, and have been seen in the fontanelles, particularly the posterior fontanelle. It is unclear at this time exactly how or why they are formed, although genetic as well as environmental factors have been proposed. Their initial formation is thought to be caused by a degree of dural strain and increased sutural width. These conditions can result from mechanically induced stress due to intentional deformation like that practiced in ancient cultures, premature sutural closure, or from reduced skull ossification as seen in metabolic bone diseases. The cause of the malformation can have an influence on the number and location of Wormian bones. Clinically, Wormian bones are used as markers in the diagnoses of many autosomal dominant genetic disorders, namely, craniosynostosis and osteogenesis imperfecta.

The study of the lymphatic system has a lengthy history, with many notable medical minds making important contributions. We now appreciate that this system is an essential component of the immune system, as well as vital to the maintenance of fluid homeostasis within the body. A good knowledge of the lymphatic system is clinically important concerning cancer, edema, surgery, and the immune response. This article reviews the history of the evolution and discovery of the lymphatic system.

Knee pain is a very common complaint seen in the clinical setting. A torn medial meniscus, osteochondral defects, inflammation, or an irritated medial plica are some of the most common causes of medial knee pain. Plicae are synovial invaginations that are believed to be remnants of the embryological development of the knee. They have a potential to become inflamed and symptomatic. Diagnosis of medial plica syndrome involves physical exam and imaging studies, but the current gold standard is arthroscopy and therefore a definitive diagnosis cannot be made until surgery. As such, medial plicae are the most commonly missed diagnoses in the knee as it is purely a clinical diagnosis. Medial plica syndrome can be treated with physiotherapy, corticosteroid injections, or surgery. Overall, good outcomes have been seen following diagnosis and treatment of medial plica syndrome, with patients returning to their preferred levels of activity. This article reviews the topic of medial plica syndrome.

OBJECTIVE This study aims to quantify the impact of vancomycin powder application on new bone formation and spine fusion rates in a rat posterolateral arthrodesis model. METHODS Thirty-six female Sprague-Dawley rats underwent a posterolateral lumbar spinal fusion (PLF) at the L-4 and L-5 vertebrae. Fusion was elicited via implantation of an absorbable collagen sponge containing 3 µg rhBMP-2. Rats were divided into 3 groups: no vancomycin (control), standard-dose vancomycin, and high-dose vancomycin, based on what was applied to the fusion bed. Clinical studies typically describe the application of 1 g vancomycin into the surgical wound. Presuming an average individual patient weight of 70 kg, a weight-based equivalent dose of vancomycin powder was applied subfascially in the PLF model constituting a “standard-dose” treatment group (14.3 mg/kg, n = 12). To determine whether there is a critical threshold beyond which vancomycin increases the risk of pseudarthrosis, a 10-fold higher dose was administered to a “high-dose” treatment group (143 mg/kg, n = 12). No vancomycin powder was applied to the surgical site in the control group (n = 12). Fusion was evaluated with plain radiographs at 4 and 8 weeks after surgery. The spines were harvested after the 8-week radiographs were obtained and evaluated using manual palpation, microCT analysis, and histological analysis. RESULTS Radiographs demonstrated equivalent bridging bone formation in all groups. No significant differences in fusion scores were seen in the standard-dose (mean 2.25) or high-dose (2.13) treatment groups relative to untreated control animals (1.78). Similarly, fusion rates did not differ significantly different between vancomycin-treated animals (100% for both groups) and control animals (92%). Quantification of new bone formation via microCT imaging revealed no significant between-groups differences in the volume of newly regenerated bone (control vs standard-dose vancomycin, p = 0.57; control vs high-dose vancomycin, p = 0.53). CONCLUSIONS This is the first in vivo study to specifically address the development of pseudarthrosis after intrawound application of vancomycin during fusion surgery. Our results demonstrate that vancomycin powder does not inhibit fusion rates at a dose that is the weight-percentage equivalent of what is routinely used by surgeons. Moreover, bone formation and fusion rates were not reduced even after administration of a vancomycin dose that is 10-fold higher than that which is typically administered clinically. Our findings suggest that if there is a critical threshold above which vancomycin inhibits bone healing, such a dose is out of the range which might be considered reasonable for clinical use.

Development of a pharmacologic agent that reduces the adverse effects of cigarette smoke on bone-healing could prove useful to orthopaedic surgeons. Since dioxin and other similar cigarette smoke toxins exert their effects through Ahr pathway activation, the receptor represents a potential therapeutic target to improve spinal fusion rates in patients who smoke.