© ISAKOS 2017
Alberto Gobbi, João Espregueira-Mendes, John G. Lane and Mustafa Karahan (eds.)Bio-orthopaedics10.1007/978-3-662-54181-4_1010. Orthopedic Sports Disorders: Genetic and Molecular Aspects
(1)
Full Professor the Department of Orthopedics and Sports Medicine from Universidade Federal de Sao Paulo- Escola Paulista de Medicina, São Paulo, SP, Brazil
(2)
Afilliate Professor from Department of Orthopedics and Traumatology from Universidade Federal de Sao Paulo- Escola Paulista de Medicina, São Paulo, SP, Brazil
(3)
Fellow in Sports Medicine from Department of Orthopedics and Traumatology from Universidade Federal de Sao Paulo- Escola Paulista de Medicina, São Paulo, SP, Brazil
10.1 Introduction
The practice of sports worldwide has been increasing during the last decades. Similarly, the increase of orthopedic lesions related to sports has been noticed [1]. Innumerable aspects have been described as risk factors for the appearance of musculoskeletal sports lesions, such as overtraining [2], incorrect sports technique [2], inadequate nutrition [2], previous injury [2], higher age [3], obesity [3], and factors related to the athlete’s behavior [2].
Furthermore, genetic and molecular aspects have been implicated with the occurrence of orthopedic sports disorders. In 1994, a familial relationship of anterior cruciate ligament injuries was first described [4]. Since then, other studies have been published relating genetic and molecular aspects with different sports lesions in the whole body, such as knee ligament and meniscus injuries [5–20], shoulder instability [5, 21, 22], muscle injuries [23–25], and Achilles tendinopathy [13, 26–28].
Ahead we will discuss the genetic and molecular aspects in specific musculoskeletal sports lesions that have already been described in the current literature.
10.2 Knee Injuries
10.2.1 Ligament Injuries
The anterior cruciate ligament has been the primarily structure studied in regard to genetic and molecular factors related to its lesion. The association of a chromosomal region (11q22) and risk of ACL rupture was showed by Posthumus and colleagues [6]. A higher genetic component in the subgroup that suffered noncontact mechanism of ACL injury was evidenced.
Collagen is the main tissue component of the anterior cruciate ligament (75% of the dry weight), with type I collagen accounting for 85% of the collagen [29]. Having this major role of collagen in the structure of the ACL, many studies evaluating ACL injury and different genes that encode types of collagen that are present on the ACL structure were conducted and were able to show a relation between them. The collagen types and their respective genes associated with ACL lesion are collagen type I (COL1A1) [5, 14, 16], type III (COL3A1) [9, 15], type V (COL5A1) [7, 9, 17], type XII (COL12A1) [9, 11], type XIV (COL14A1) [17], and type XV (COL15A1) [17].
Besides collagen, other molecular aspects were investigated. Matrix metalloproteinases (MMP) are a zine endopeptidases [30] capable of degrading extracellular matrix. There are many types of MMP and most of them are synthesized by fibroblasts. MMP expression is required when remodeling of extracellular matrix is intended. Relationship between ACL injury and MMP has been described, particularly within types MMP-3 [18] and MMP-12 [6].
Despite being <1% of dry weight of the anterior cruciate ligament [29], proteoglycans are also important substances that were studied aiming on finding relationship to ACL injury. The genes encoding the proteoglycans aggrecan and decorin [8] were associated with ACL injury. Nonetheless, genes involved in the angiogenesis-associated signaling pathway [12] also had its relationship to ACL injury described in the literature.
10.2.2 Meniscus Injuries
Meniscus is a common knee structure injured in sports activities. In a study evaluating the gene expression signatures in the traumatic and degenerative meniscus tears, Brophy et al. [19] found that chemokines and matrix metalloproteinases were expressed at a significantly higher level in traumatic tears, while the gene encoding type I collagen, COL1A1, was expressed at a lower level in traumatic tears compared with degenerative tears.
Another study conducted by Brophy and colleagues [20] evaluate gene expression in isolated meniscus tears and meniscus tears associated with anterior cruciate ligament according to patient age and sex. There was a higher expression of arthritis-related markers such as IL-1β and matrix metalloproteinases in patients under 40 years old. Nonetheless, higher expression of catabolic markers was found in patients with concomitant meniscus and ACL injuries, suggesting a higher risk to develop osteoarthritis in patients with this combined injury.
10.3 Shoulder Injuries
One of the most common sports lesions in the shoulder is the traumatic dislocation of the glenohumeral articulation, often leading to shoulder instability. In a study evaluating gene expression in collagen cross-linking and its regulation in traumatic shoulder instability, Belangero and associates [21] showed that there is an association between the expression of TGFβ1, TGFβR1, LOX, and PLOD2 and shoulder instability.
Another study evaluating shoulder instability by Belangero and colleagues [22] focused on studying the collagen-encoding genes of collagen types I, III, and V in the glenohumeral capsule after an episode of shoulder dislocation. They found deregulated expression of collagen genes across the capsule of shoulder instability patients, which may lead to modifications of collagen fibril structure and impairment of the healing process, possibly with a role in capsular deformation that is a key factor in the shoulder instability.
10.4 Muscle and Tendon Injuries
Muscle injuries are the most common sports lesions representing 10–55% of all lesions sustained by athletes [31]. Pruna and colleagues [24] conducted a study to evaluate genetic risk factors regarding susceptibility to injuries in professional football players. They showed that specific single nucleotide polymorphisms (SNPs) were associated to degree of injury and recovery time of muscle injuries. However, no evidence was found between the genes studied and degree of injury and recovery time of tendon injuries. A single nucleotide polymorphism (SNP) is a DNA sequence variation that occurs when a single nucleotide in the genome differs between paired chromosomes in a given individual.
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