REGENERATIVE THERAPIES FOR MUSCULOSKELETAL CONDITIONS
PERCUTANEOUS TENOTOMY
Percutaneous tenotomy involves the introduction of a needle into damaged soft tissues, most often tendons (“needling”), in an effort to stimulate a healing response and resect the diseased tendon tissue. Although tenotomy was initially performed as an open or arthroscopic surgical technique, advances in US technology have led to improved sensitivity and specificity identifying areas of tendinous injury (hypervascularity, hypoechogenicity, and calcification); as such, the combination of these techniques has been used in the outpatient setting. New commercial models incorporate ultrasound guidance with needles or micro-resection probes for real-time débridement of damaged tissues. Percutaneous tenotomy has been described in the management of tendinopathy involving the rotator cuff, medial and lateral epicondyles, patellar and Achilles tendons, and plantar fascia.
Housner and colleagues9 evaluated the safety and short-term efficacy of US-guided needle tenotomy in 13 patients with chronic tendinosis of the patella, Achilles tendon, gluteus medius, iliotibial tract, hamstring, and rectus femoris. They reported no procedural complications and a significant decrease in pain scores at 4 and 12 weeks of follow-up.
Koh and colleagues10 conducted a prospective case series to evaluate the safety and efficacy of office-based, US-guided percutaneous tenotomy (using a commercial model) on 20 patients with chronic lateral epicondylitis. The authors reported no wound complications and significant improvement in pain scores at each follow-up period up to 1 year. Subsequent post-procedural US evaluation of injured tissues revealed evidence of healing (decreased tendon thickness, vascularity, and hypoechogenicity) in over half the cohort after 6 months compared with the baseline.11
Lee and colleagues12 evaluated the efficacy of US-guided needle tenotomy combined with platelet-rich plasma (PRP) injection on chronic recalcitrant gluteus medius tendinopathy. In this case series, 21 patients underwent PRP and “needling” through the hypoechoic regions of the injured tendon under direct US guidance. After a period of rest, all patients completed the structured rehabilitation protocol. After an average follow-up of 10 months, all patients displayed significant improvements in all outcome questionnaires and did not report any significant adverse events. The authors concluded that tenotomy combined with PRP is a safe and effective method for treatment for recalcitrant gluteus medius tendinopathy.
These studies indicate that US-guided percutaneous tenotomy, alone or in combination with regenerative therapies, such as PRP, is a safe and effective treatment option for various tendinopathies. However, while tenotomy appears safe with promising results and no reported major adverse events, the level of evidence remains low.
ORTHOBIOLOGICS
Orthobiologics are substances composed of biological materials that can be used to aid or even hasten the healing of bones, muscles, tendons, and ligaments. Orthobiologics may contain growth factors, which initiate or stimulate the body’s reparative process; matrix proteins, which serve as scaffolding for healing tissues; or stem cells, specifically adult stem cells, which are multipotent and can differentiate into several cell lines. Adult stem cells are categorized as hematopoietic, neural, epithelial, skin, and mesenchymal types. Mesenchymal stem cells (MSCs) are of particular interest in sports medicine applications because they secrete growth factors and cytokines with trophic, chemotactic, and immunosuppressive properties.13 MSCs are also multipotent and can differentiate into bones, muscles, cartilages, and tendons.14-17MSCs are readily isolated from many sources, including bone marrow, adipose tissues, synovial tissues, peripheral blood, skeletal muscles, umbilical cord blood, and placenta.13,14Several types of regenerative therapies used in orthopedic and sports medicine practice include PRP, stem cell therapy, and amniotic membrane/fluid preparations. While each therapy possesses the potential for promising results, the paucity of research and discrepancies among studies regarding the description of stem cell lines used limit the available evidence on the true clinical benefits of these regenerative therapies.
[HEAD 3] PLATELET-RICH PLASMA
PRP is an autologous product that has been used to stimulate biological factors and promote healing since the 1970s. Through the activation of platelets, PRP improves localized recruitment, proliferation, and differentiation of cells involved in tissue repair. Platelets, which are non-nucleated bodies located in peripheral blood, contain and release 3 groups of bioactive factors that enhance the healing process. Growth factors and cytokines released from alpha-granules play a role in cell proliferation, chemotaxis, cell differentiation, and angiogenesis. Bioactive factors, such as serotonin and histamine, released from dense granules, increase capillary permeability and improve cell recruitment and migration. Adhesion molecules also assist in cell migration and creation of an extracellular matrix, which acts as a scaffold for wound healing.18 Platelets are activated by mechanical trauma or contact with multiple activators, including Von Willebrand factor, collagen, thrombin, or calcium chloride. When activated, platelets release growth factors and cytokines, which create a pro-inflammatory environment that mediates the tissue repair process. After the procedure, the pro-inflammatory environment may result in patient discomfort, which can be managed with ice and acetaminophen. Use of nonsteroidal anti-inflammatory drugs may theoretically inhibit the inflammatory cascade induced by PRP, and they are avoided before and after the procedure, although evidence regarding necessary time frames is lacking.
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