Biologics in Sports Medicine—Introduction

Disclosures

Laura A. Vogel declares no conflicts of interest; Mary Beth R. McCarthy receives intellectual property royalties from Arthrex, Inc.

Augustus D. Mazzocca is a paid consultant for Arthrex, Inc. and Orthofix, Inc. and receives research support from Arthrex, Inc.

Introduction

Biologic therapies have been an area of interest within sports medicine for many years as a means to maintain function in both active and aging populations. Over the last 2 decades, however, surgeon interest and industry development have significantly increased. The market for biologic therapies within orthopedic surgery was estimated to be a $3.7 billion dollar industry in 2013 and is expected to continue to increase in worth.

In general, the goal of biologic therapies is enhanced healing and restoration of normal, native tissue or anatomy. Enhanced healing can be defined as improved quality of the healing tissue, decreased healing time, or improved healing rates. Examples of restoration of normal, native tissue include restoration of articular hyaline cartilage versus fibrocartilage or normal tendon to bone insertion anatomy. The variety of available biologic therapies is vast, and there is an equally large variability in the available preparations, applications, delivery systems, and outcome measurements. Biologic therapies can be used to augment other procedures or as stand-alone treatments; they can be largely divided into growth factor treatments, cell therapies, or tissue transplantations. In this chapter, we aim to provide the reader with an overview of biologic therapies in sports medicine by reviewing historical origins of biologic therapies, currently available biologics in sports medicine, and future directions for research and treatment.

Historical Perspective

Even before the advent of cutting edge biologic therapies, surgeons have attempted to improve healing in difficult cases. Bone graft is one of the original biologic treatments. The earliest report of viable bone allograft was in 1770 by John Hunter, a Scottish surgeon and anatomist. He transplanted a bony spur from a rooster foot into its comb and found that it still grew normally owing to the rich vascular supply of the rooster’s comb. The first report of a successful human bone allograft transplantation was in 1879 by Sir William MacEwan, a British surgeon, in which he successfully reconstructed two-thirds of the humeral shaft of a 3 year old boy with extensive osteomyelitis.

The modern concept of tissue grafting and banking began in the early 1900s. Tissue was frequently solicited from patient’s friends or family, and bone was often obtained from amputees. Obtaining tissue from corpses was rarely done at that time owing to concerns regarding infection and disrupting death rites and burial rituals. The US Navy Tissue Bank was founded in 1949 and established the standard of modern tissue banks. At its inception, the bank consisted of a single small freezer in which they collected and stored surplus bone from clean cases until needed for later grafting. Issues around allograft immunogenicity and disease transmission, including human immunodeficiency virus (HIV), were prevalent in the 1960s–1980s. This led to the development of modern preservation methods and protocols for donor screening. The use of human cell, tissue, and cellular and tissue-based products in the United States is regulated by the U.S. Food and Drug Administration (FDA). In order to be classified as a low-risk product (also known as 361 low-risk products vs. high-risk 351 products) that does not require specific licensing, there are four criteria that must be met. They are (1) minimal manipulation, (2) homologous use, (3) noncombination products, and (4) lack of systemic effect. These regulations affect the availability of emerging technologies to patients and clinicians in the interest of patient safety.

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