The practice of medicine is ever-changing and with the exponential advancement of biotechnology, the field is developing and progressing faster than ever. We are continuously inundated by new medications, medical devices, and surgical equipment. The field of orthopaedic surgery is no exception, with constant improvements in arthroscopic techniques and implants for joint arthroplasty that provide more effective treatment options for patients. However, despite these advancements, daily challenges still exist in orthopaedics. For example, while total joint arthroplasty has been an extremely successful option for geriatric patients, owing to the limitations in long-term implant durability, it is a less desirable procedure for the younger and active patients. Instead, these patients will benefit from orthobiologic treatments that target cartilaginous healing or regeneration.

Due to an improved understanding of the role that particular cells and growth factors play in tissue healing and restoration, orthobiologics have emerged as a new class of substances that are intended to accelerate, improve, and augment biologic healing. The use of orthobiologics is a novel way to treat many orthopaedic diseases. Orthobiologics function by harnessing or mimicking natural growth factors found within the body and redirecting their use to accelerate recovery and tissue healing.

Over the past few decades, orthobiologics have evolved tremendously. The first generation of orthobiologics was composed of hyaluronic acid (HA) in the form of viscosupplementation. It was then followed by platelet-rich plasma, the first autologous form of orthobiologics ( Fig. 1.1 ). More recently, cell therapies using stem cells have emerged as the third generation of orthobiologics. However, the use of orthobiologics has outpaced its validation. In this chapter, we will explore the different roles of biologics in orthopaedics. These topics will also be revisited in more detail in subsequent chapters.

Angel System by Arthrex (Naples, FL), which centrifuges whole blood from the patient to acquire platelet-rich plasma for the injections.

Viscosupplementation was the first orthobiologic developed to treat joint arthritis. It was initially used in Europe and Asia and was approved by the U.S. Food and Drug Administration in 1997. When conservative treatment modalities (such as a physical therapy, pain medications, and intraarticular steroids) fail to manage symptoms of joint arthritis, viscosupplementation can be injected into the affected joint as another treatment option. The HA found in these injections is derived from processed poultry combs and is intended to mimic hyaluronan, a gellike liquid found naturally in synovial fluid. HA works by lubricating the articular surfaces of a joint and absorbing shock to reduce joint loads.

Intraarticular HA (IAHA) has been used for more than 20 years, especially for the management of knee osteoarthritis. HA injection has also been used off-label to treat shoulder and ankle arthritis. Nonetheless, the effectiveness of IAHA is still heavily debated. While the Osteoarthritis Research Society International (OARSI) and the American College of Rheumatology (ACR) initially recommended IAHA to treat knee arthritis, they now only conditionally recommend it. Furthermore, the American Academy of Orthopedic Surgeon Clinical Practice Guidelines do not recommend the use of HA for the symptomatic treatment of knee osteoarthritis. Trigkilidas and Anand (2013) looked at 14 randomized controlled trials (RCTs), of which 12 studies compared HA with a placebo. Out of the 12 RCTs, five trials reported no statistically significant difference between the two groups. The other seven studies suggested varying degrees of IAHA effect. Consequently, there have been many systematic reviews and metaanalyses of the literature that have attempted to reach a definitive conclusion about the efficacy of HA for knee arthritis. The conclusions from the reviews are controversial. Of these, some reviews supported the use of viscosupplementation as opposed to placebo, acetaminophen, and nonsteroidal antiinflammatory drugs (NSAIDs). On the contrary, the other reviews state that viscosupplementation is not an effective therapy because of the marginal clinical benefit, increased risk of adverse events, and only recognizable short-term effects.

PRP, also known as platelet-enriched plasma, platelet-rich concentrate, and autogenous platelet gel, is the plasma fraction of autologous blood that has a higher platelet concentration. A platelet count of 4–5 times the baseline must be present to classify plasma as PRP, and it is the first orthobiologic in the form of an autologous blood product. PRP was first used for open heart surgery by Ferrari et al. in 1987 and first applied in orthopaedic surgery for bone healing by Marx et al. Since then, PRP has been used for numerous musculoskeletal conditions including decreasing symptoms in chronic conditions such as knee osteoarthritis and tendinopathies of the patellar tendon, elbow, and Achilles. PRP has also been investigated for its use in accelerating fracture healing of nonunions and bone to tendon healing in anterior cruciate ligament (ACL) reconstruction and rotator cuff repair.

PRP has its origins in autologous blood injections (ABI), which introduce the patient’s own venous blood to the desired area ( Fig. 1.2 ). However, the results of ABI had been inconsistent owing to the delivery of multiple blood components, such as red blood cells and white blood cells, which do not have healing properties. However, the practice of using autologous blood to accelerate the healing process of damaged tissues continues to dramatically evolve as researchers gained a better understanding of the role of platelets not only in hemostasis but also in the regeneration of tissues. The discovery of growth factors contained in the α-granules of platelets led to the use of concentrated platelets in the form of PRP. There are approximately 50–80 α-granules and more than 30 different proteins in a mature platelet. Some of the important proteins include platelet-derived growth factor (PDGF), transforming growth factor (TGF), epidermal growth factor (EGF), fibroblast growth factor (FGF), and vascular endothelial growth factor (VEGF). The production and secretion of such growth factors directly influence the regenerative potential of PRP. Activated platelets quickly start releasing the proteins from α-granules within minutes and continue to generate and discharge these factors for the additional days of their life span. There are many different preparations of PRP available including both leukocyte-rich and -poor concentrates that can be applied in two different ways: activated and nonactivated. However, there is no consensus on the standards of PRP preparation, which makes it difficult to compare available studies in the literature. Two classification systems have been proposed based on different PRP preparations ( Tables 1.1 and 1.2 ). Currently, PRP is being used in orthopaedic conditions that are commonly complicated by chronicity including osteoarthritis, lateral epicondylar tendinopathy, and patellar or Achilles tendinopathy.

First step in the autologous platelet-rich plasma preparation. Blood is taken from the patient before the centrifuge step.

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FDA Regulations and Their Impact Growth Factors Biologics in Orthopaedic Surgery Preserving the Articulating Surface of the Knee Biologics in Hand Surgery Biologics in Musculoskeletal Oncology

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