The authors of Augmentation of Tendon-to-Bone Healing review some of the methods currently under investigation for increasing the quality of this complex healing challenge.
Osteoinductive Growth Factors
Transforming growth factor, bone morphogenetic protein, fibroblast growth factor, and granulocyte colony-stimulating factor have shown some positive effects on the repair and healing of tendon and bone tissues in animal model studies.
Platelet-Rich Plasma
Although basic-science studies suggest positive effects on tendon-to-bone healing, clinical evidence from controlled human trials involving rotator cuff tendons does not show any superiority of platelet rich plasma augmented repairs over conventional methods.
Gene Therapy
Viral or nonviral vehicles can be used genetically modify cells to express growth factor at the tendon-bone insertion site. Before gene transfer can be tried as a therapeutic method to improve tendon-to-bone healing in humans, questions regarding safety and regulatory issues need to be answered.
Enveloping The Grafts With Periosteum
While enveloping the grafts with periosteum appears to be a promising approach, clinical evidence supporting its use in humans to augment tendon-to-bone healing is lacking.
Osteoconductive Materials
Calcium or magnesium-based osteoconductive materials are readily available and relatively inexpensive compared with other biological treatment modalities. Further research is required to prove them as biocompatible and effective treatment alternatives to reconstruct the tendon-to-bone interface in humans.
Cell-Based Therapies
The knowledge about the conditions that are required to choose a certain type of stem cell, optimum cell amount, and delivery vehicles, is limited. Serious concerns exist regarding their potential for differentiation into undesirable lineages, which could result in tumor-like growth.
Biodegradable Scaffolds And Biomimetic Patches
Biocompatible and biodegradable scaffolds with porous ultrastructure permit invasion and easy attachment of cells, while creating an environment suitable for cell proliferation and differentiation as demonstrated in models. The success of these approaches will require a thorough understanding of the structure-function relationship at the native insertion site, as well as the elucidation of the mechanisms governing interface regeneration.
Low-Intensity Pulsed Ultrasound
Low-intensity pulsed ultrasound may promote osteoblast and fibroblast proliferation, which may contributes to improved collagen formation and bone remodeling.
Extracorporeal shockwave treatment can affect bone by exertion of direct pressure or by causing cavitation. These factors may create an environment with a better blood supply and increased bone and collagen formation, which may create a stronger tendon-to-bone interface.
Effects Of Various Loading Methods And Immobilization On Interface Healing
On the basis of animal models, neither strict immobilization nor immediate initiation of rehabilitation and loading appear to be beneficial after surgical repair, but rather a balance between the modalities is needed to optimize the healing enthesis and obtain a stronger interface.
Coated Sutures And Interference Screws
As with other growth factor delivery vehicles, challenges remain, including timing, dosages, degree of elution, sustainability of the release, effects of coating on fixative materials, and safety.
Delayed Interface Healing
Research is attempting to identify molecules and/or conditions that may delay the healing of the tendon-bone interface. Evidence from animal model studies has also shown that conditions that negatively impact bone formation and fracture-healing, such as uncontrolled diabetes mellitus, nicotine, and nonsteroidal anti-inflammatory drugs, also negatively affect tendon-to-bone healing.
Conclusion:
Knowledge about the complexity of tendon-to-bone healing is still limited and mainly based on animal studies. Rigorous clinical trials must be conducted to determine the value - benefit/(cost+risk) - of these approaches.
As we've pointed out in prior posts, atraumatic failure of the rotator cuff insertion is a degenerative process. Even if we could artificially manipulate the environment at the site of surgical reattachment, we not be able to "un-degenerate" the tendon or to prevent repeat failure after surgery.
As we've pointed out in prior posts, atraumatic failure of the rotator cuff insertion is a degenerative process. Even if we could artificially manipulate the environment at the site of surgical reattachment, we not be able to "un-degenerate" the tendon or to prevent repeat failure after surgery.
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