OKOJ, Volume 14, No. 10

Shoulder Instability

Shoulder instability represents a broad and complex range of pathology, generally classified into anterior, posterior, and multidirectional categories. Recent research emphasizes the importance of glenoid and proximal humeral bony defects in recurrent anterior dislocation. The general understanding of the natural history, pathoanatomy, and surgical techniques surrounding shoulder instability continues to improve.

    • Keywords:
    • anterior shoulder instability

    • glenoid bone loss

    • Hill-Sachs lesion

    • multidirectional shoulder instability

    • posterior shoulder instability

    Bone Grafting in Spinal Surgery

    The choice of substrate(s) to use for bone grafting in spinal arthrodesis is complex. Numerous options exist to increase the likelihood of achieving a stable fusion. In addition to local bone and iliac crest bone graft, which is the gold standard for spinal surgery, multiple formulations are available to augment the volume of graft material and optimize the biochemical milieu for bone formation. Bone graft extenders, replacements, and enhancers all work to promote an environment that is favorable for growth. Bone morphogenetic protein, bone matrices, ceramics, and mesenchymal stem cells are commonly used substrates that have had a favorable effect on spinal surgery. Although nonautologous grafting materials can be advantageous, it is important to discuss with patients the risks inherent to each of these substances before their use in surgery.

      • Keywords:
      • iliac crest bone graft

      • bone graft extenders

      • bone morphogenetic protein

      • cellularized bone matrix

      Fracture Repair: Update on Mechanism and Antagonists

      Fracture healing is a complex biologic process that involves specific regenerative patterns and changes in the expression of several gene pathways. After the initial trauma, bone heals by a direct intramembranous or an indirect fracture-healing process, which consists of intramembranous and endochondral bone formation. These two processes involve a series of four temporally defined phases of repair: inflammatory, early callus, mature callus, and remodeling. Many factors influence the inflammatory phase, including the arachidonic acid metabolism and Wnt pathway agonists and antagonists. The early callus, late callus, and remodeling phases are modulated by factors that affect the receptor activator of the nuclear factor-kappa B ligand pathway. These factors include denosumab, osteoprotegerin, parathyroid hormone, strontium ranelate, and estrogen. Parathyroid hormone indirectly affects this pathway by binding to the osteoblasts. Binding stimulates the osteoblasts to increase their expression of receptor activator of nuclear factor-kappa B ligand and inhibits their expression of osteoprotegerin. Diphosphonates directly modify the effects of bone resorption by acting on the osteoclast, thus modulating the remodeling phase of fracture healing. It is important to review the specific pathways of fracture healing modification along with risk factors for impaired bone healing in fractures classified as patient dependent, or modifiable, and patient independent, or nonmodifiable.

        • Keywords:
        • fracture healing

        • receptor activator of nuclear factor-kappa B ligand inhibition

        • Wnt fracture healing pathway

        • biology of bone healing

        • primary bone healing

        • secondary callus formation