Sports-related injuries are expected to increase with time and health-care professionals of all disciplines are becoming aware of common injuries and their treatment. Sports medicine is expanding in recognition of the fact that: (1) athletes participate in sport-specific training year round and often in multiple sports, (2) there has been a steady increase in “weekend warriors”, (3) the patient population is better educated and has higher performance expectations and a greater awareness of physical fitness, and (4) recreational activities for the general population have increased tremendously. This chapter provides a brief overview of the current state of management of common sport-related injuries, including injuries in the shoulder, elbow, hip, knee, foot and ankle, head and spine, and concussion. It also describes some of the current controversies existing in these areas. The topics of cartilage, soft tissue injury, stem cells in orthopedics, proprioception in sports, biologics and imaging are also addressed in terms of current issues and what the future holds for their application in orthopedic sports medicine.
KeywordsAnterior Cruciate Ligament Rotator Cuff Anterior Cruciate Ligament Reconstruction Posterior Cruciate Ligament Femoral Tunnel
In the USA, the first American Academy of Orthopedic Surgeons sub-committee on sports medicine was formed in 1967 with the first American Orthopedic Society for Sports Medicine (AOSSM) meeting held in New Orleans in 1975. Currently, there are over 2600 members in the AOSSM and 81 accredited fellowship programs. Sports-related injuries are expected to increase with time and health care professionals of all disciplines are becoming aware of common injuries and their treatment. Both the breadth and depth of sports medicine is expanding in response to the fact that: 1) athletes participate in sport-specific training year round and often in multiple sports, 2) there has been a steady increase in “weekend warriors”, 3) the patient population is better educated, has higher performance expectations, and an increased awareness of physical fitness, and 4) recreational activities for the general population have increased.
Orthopedic sports physicians specialize in the operative and non-operative management of the active individual. Their patient population ranges from those in the general population who choose to live an active lifestyle to the care of dedicated professional athletes. Training in arthroscopic surgery is required to treat intra-articular derangements of the shoulder, elbow, wrist, hip, knee, and ankle. The orthopedic sports specialist is further qualified to manage acute on-field injuries and make decisions for the injured athlete that are in his or her best interest in the face of pressures from the team, fans, family, and even from the injured individuals themselves. The academic sports specialist is also involved in contributing to the vast field of sports research, whether it is on the cellular, biomechanical, or clinical level. Orthopedic sports specialists also help promote awareness of new methodologies and philosophies in sports-related care, two areas that are in constant flux and improvement, at the hundreds of centers of excellence worldwide. Sports medicine is one of the few orthopedic sub-specialties in which the surgeon is not simply treating the patients’ pain, but rather, has the added challenge of optimizing athletic function. This chapter provides a brief overview of the scope of sports medicine, including a description of current treatments and controversies as well as its future directions.
1.2 Rotator Cuff
Pathology of the rotator cuff is one of the most common reasons for visits to the orthopedic sports specialist. In the last decade, treatment of rotator cuff injuries has significantly improved, with adjustments made to surgical indications, surgical techniques, surgical philosophy, and rehabilitation protocols. Whereas in the past, the results of arthroscopic rotator cuff surgery were questioned regarding the advantages over open or mini-open methods of repair, the recent literature has shown arthroscopic rotator cuff to be equal, if not superior to open techniques [1, 2, 3, 4]. Current controversies in rotator cuff surgery include single- vs. double-row fixation, the utility of acromioplasty, the difficulties in treating massive cuff tears, and the incorporation of the dozens of constantly evolving surgical devices and biological agents that have continued to flood the industry. Several recent reviews of the literature have failed to show a clinical difference between double-row and single-row techniques of rotator cuff repair [5, 6]. A systematic review by Wall et al. showed that in three level-one studies and two level-two studies there was no clinical difference at one year in the single-row vs. double-row technique for rotator cuff repair . However, Wall et al. also systematically reviewed the literature on the biomechanical strength of single- vs. double-row rotator cuff repair and concluded that the biomechanical properties of the double-row technique are superior to those of the single-row technique .
1.3 Shoulder Instability
The treatment of shoulder instability is one of the primary reasons for younger athletes to see the orthopedic sports specialist. Studies have characterized the risk for future recurrence and have found that those in their teens and twenties have a significantly higher risk of repeat episodes of instability than those in their thirties and forties [9, 10, 11]. Controversy remains regarding whether or not to immobilize the shoulder of a patient presenting with a dislocation for the first time, the position of the immobilization, and the considerations for early surgical repair of the capsulolabral structures. Patients with atraumatic multidirectional instability have generally been treated with shoulder rehabilitation, and in some cases surgical indications may be revised. Finally, those patients with recurrent instability are being more closely evaluated for the etiology of their pathology. Depending on whether the etiology is due to capsulolabral laxity, bony glenoid deficiency, humeral head morphology, etc., treatments can vary. Arthroscopic soft-tissue restoration has been the front-line treatment for recurrent instability. However, it is backed by open stabilizing procedures such as the open Bankart repair, Latarjet procedure, remplissage, and humeral head morphology restoration with allograft.
1.4 Superior Labrum/Biceps Anchor/Acromioclavicular Joint
The diagnosis and treatment of superior labral and biceps anchor pathologies is a common challenge for the orthopedic sports physician. Conservative vs. operative treatment have had mixed results depending on the level of activity, type of superior labral tear, and concurrent pathology. Also, the debate over biceps tendon tenotomy vs. tenodesis remains an active issue for the orthopedic surgeon [12, 13]. The sports medicine literature is evolving in the development of an algorithm for the treatment of superior labral and biceps disease. Disorders of the acromioclavicular joint can be acute or chronic. Acute type I and type II acromioclavicular separations have traditionally been managed non-operatively, but controversy exists over early vs. delayed surgical reconstruction of the type III acromioclavicular disruption [14, 15]. Chronic end-stage acromioclavicular arthrosis, traditionally managed with an open distal clavicle resection, is increasingly being treated arthroscopically, with excellent results [15, 16]. Chondrosis of the shoulder continues to be a challenge for the sports specialist. Arthroscopic debridement of the arthritic shoulder is a short-lasting option with early promising results for added microfracture techniques . Diffuse chondrosis refractory to alternative management has been treated with humeral hemi-arthroplasty or glenohumeral arthroplasty.
The throwing athlete is particularly susceptible to ulnar collateral ligament injury and its associated sequelae [18, 19]. While the gripping athlete (e.g., tennis and golf) is predisposed to tendinopathies about the elbow , common elbow pathologies include lateral and medial epicondylitis, triceps rupture/tendinitis, olecranon bursitis, distal biceps rupture, ulnar collateral ligament injuries, valgus extension overload, osteochondritis dissecans (OCD), elbow arthritis, ulnar neuropathy, fractures, and dislocations.
Arthroscopic treatment of intra-articular elbow pathology has advanced over the past decade, with indications expanding beyond simple diagnosis and loose-body removal. The arthroscope is being used to treat impingement, arthritis, contractures, OCD stabilization, and certain intra-articular fractures . Techniques and procedures continue to evolve as surgeons gain more insight and skill in the indications for arthroscopic treatments of the elbow.
1.6 Hand and Wrist
Hand injuries during athletic participation are common and the sports orthopedic specialist is often the front-line physician seeing these athletes. While many hand injuries are ultimately cared for by a hand surgeon, the sports orthopedist must be facile in the diagnosis and management of acute hand injuries. Common acute injuries include dislocations, fractures, and ligamentous injuries. Wrist arthroscopy has also benefited from advances in surgical technique and equipment advances. Current usage of wrist arthroscopy includes evaluation of chronic wrist pain, treatment of triangular fibrocartilage complex and ligament tears, resection of synovitis and joint-based ganglia, visualization for reduction and fixation of intra-articular fractures and acute carpal dislocations, treatment of ulnar styloid impaction syndrome, loose-body removal, and debridement and partial or complete ostectomy for arthritis .
The approach and treatment of intra-articular hip pathology in the active individual has seen a dramatic change over the last five years. Disease of the labrum and femoroacetabular impingement (FAI) are diagnoses that are being made with more evidence and confidence. FAI has been shown to present in two varieties: cam-type impingement refers to the abnormal morphology of the femoral head/neck junction while pincer-type impingement refers to morphological abnormalities on the acetabular side, with many patients being affected by a combination of both. Ultimately, both have been shown to cause labral and chondral disease [23, 24, 25, 26]. Concordantly, arthroscopic treatment of these conditions has also seen a dramatic rise, with demonstrated success for osteo-chondroplasty as well as labral debridement and repair [27, 28, 29]. With time, long-term data will become available regarding the efficacy of arthroscopic hip surgery in treating immediate symptoms and in the prevention of long-term degeneration. Other conditions currently being treated with hip arthroscopy include septic arthritis, intra-articular loose bodies, pigmented villonodular synovitis, synovial chondromatosis, and ruptured ligamentum teres. Expansion of the indications of hip arthroscopy is on the forefront of sports medicine.
1.8 Anterior Cruciate Ligament
The anterior cruciate ligament (ACL) continues to be the most extensively researched and reconstructed of the ligaments. In 2008, there were approximately 105,000 ACL reconstructions in the USA . Despite the extent of ACL research, many controversies remain, involving autograft vs. allograft [31, 32, 33, 34], optimum allograft sterilization and processing [33, 35], location of tibial and femoral tunnel placement [36, 37, 38, 39], single vs. double bundle technique [36, 40, 41, 42, 43, 44], transtibial vs. medial portal femoral tunnel drilling [45, 46, 47], fixation methods, and post-operative protocols.
Indications for ACL reconstruction are debated. Most surgeons agree that athletic patients with a previously normal knee, with new-onset subjective instability with activity, benefit from ACL reconstruction. Thus far, the results of ACL reconstruction have largely been good to excellent, with a majority of patients able to return to pre-injury activity level . However, the challenge of improving on a generally successful operation has been proposed. Currently, “anatomic” ACL reconstruction is receiving much attention as it is felt that reconstruction of the native anatomy of the athlete with respect to graft size, tunnel location, tunnel shape, and collagen orientation results in optimal return to preinjury function.
The most common natural history of an ACL-deficient knee is chondral degeneration [49, 50]. The restoration of knee kinematics is hypothesized to be the most important factor in long-term outcomes and the prevention of early arthritis associated with current ACL reconstructions. As the anatomic technique and double-bundle concept continue to be investigated, long-term follow-up and biomechanical data will be crucial to make the necessary conclusions regading optimal reconstruction techniques.
The use of an allograft vs. autograft in ACL reconstruction has long been debated. Autografts have the disadvantage of resulting in higher surgical morbidity. Allografts incorporation and healing take longer than is the case for autografts but have the advantage of no donor site morbidity and allowing the surgeon to choose a graft size that is not constrained, unlike in autografts. Recent reviews have shown no difference in clinical outcome between autograft and allograft in ACL reconstruction [32, 33, 51].
1.9 Posterior Cruciate Ligament
The posterior cruciate ligament (PCL) has received significant recent attention. Grade I and most grade II PCL injuries are treated non-operatively. Grade III PCL and combined PCL/PLC and PCL/MCL injuries continue to challenge the orthopedist with regard to management decision-making. The natural history of a grade III PCL injury has been shown to result in medial and patellofemoral compartment chondrosis and degeneration [52, 53]. Surgical intervention is influenced by age and activity level of the patient, subjective instability, and other concurrent ligamentous injuries. There is variation amongst surgeons with regard to the “inlay” technique vs. the transtibial approach to reconstruction [54, 55]. Furthermore, the utility of osteotomy to decrease the biomechanical demand on the PCL is an unanswered question outside the laboratory. Identification of simultaneous ligament injuries and their appropriate management has been shown to influence the outcome of PCL reconstruction . The goal of PCL reconstruction should be the restoration of early stability and of knee kinematics to a near native state in order to prevent long-term complications, such as osteoarthritis. Clinical outcome studies involving PCL reconstruction are necessary to help address these unresolved issues.
1.10 Posterolateral Corner
The anatomy of the posterolateral corner (PLC) has been well characterized and shown to contribute static and dynamic stability to the knee. The critical structures of the PLC are the lateral collateral ligament (varus stability), the popliteus tendon (rotational stability), and the popliteofibular ligament (rotational stability). The PLC is commonly injured concomitant with other ligamentous injuries, with the torn ACL being its most common partner . The deficient PLC has been shown to be a primary cause of failed cruciate reconstruction surgery as it allows excessive stress on the reconstructed grafts [53, 56, 57]. Algorithms have been developed to include treatment of the PLC to avoid these disastrous consequences. Currently, it is believed that in acute high-grade injuries of the PLC in which a specific major PLC structure is obviously deficient, primary repair is effective within 2–3 weeks of the injury . However, beyond this time frame, primary repair is difficult and reconstruction of the posterolateral stabilizing structures must be undertaken. Finally, with chronic PLC injuries, ligament reconstruction may not be enough and concurrent realignment osteotomy may be necessary to prevent further chondrosis of the knee joint.
1.11 Medial Collateral Ligament
The medial collateral ligament (MCL) is the most commonly injured of the knee ligaments; however, it has been shown to have good healing potential [59, 60]. Grade I and II injuries of the MCL most commonly improve with appropriate bracing and activity modification . Grade III injuries are often given a non-operative trial, during which many also improve. A majority of MCL injuries occur in the mid-substance and femoral insertion site with a minority at the tibial insertion site. Tibial-sided grade III MCL injuries are the subset of MCL injuries associated with worse clinical outcome, and surgical repair is therefore more often advocated. Reconstruction of the MCL is less common, as repair is usually effective.
The meniscus serves to provide joint stability, shock absorption, load distribution, and proprioception. Preservation of the meniscus has recently been in the spotlight as the primary goal for meniscal surgery. With menisectomy as one of the most commonly performed surgical procedures, physicians must be educated on the significance of meniscal preservation when there is potential for healing. Research into the use of biologics (e.g. fibrin clot, PRP, platelet-rich plasma) in meniscal repair has attempted to expand the indications of meniscal repair over subtotal meniscectomy [62, 63, 64, 65, 66]. Further, meniscal root tears are now increasingly being recognized as devastating injuries resulting in the alteration of knee contact forces [67, 68]. Surgical techniques are being developed to repair the meniscal root in an attempt to restore its function. For end-stage meniscal disease, meniscal transplantation is an option , but the indications are still a source of controversy. Superior surgical techniques, the use of biologics for meniscal healing, long-term data on root repair, indications for transplantation, and physician education on the critical role of the meniscus are at the frontier of meniscal surgery.
1.13 Patellofemoral Disorders
Disease involving the patellofemoral joint is often the most difficult problem for the sports surgeon to address. Patellofemoral pathology can stem from instability, chondrosis, and tendonosis. In recent years, patellar instability has been shown to involve loss of the medial patellar stabilizing structures. In particular, the medial patellofemoral ligament (MPFL) has been identified as a primary stabilizing structure for the patellofemoral joint and has been an effective target for repair or reconstruction in the patient with chronic instability . However, treatment algorithms have recently been developed that consider the etiology of the instability and focus on treatment to address a possible anatomic cause (such as patella alta, trochlear dysplasia, and atypical tubercle anatomy). In such cases, other procedures that address this anatomic variation may be added to MPFL repair or reconstruction.
1.14 Foot and Ankle
Foot and ankle injuries are common to the athletic population. The nature of these injuries varies depending on the sport. Chronic overuse injuries are seen in endurance athletes such as long-distance runners while acute bone, ligament, tendon, or cartilage injuries are more seen in contact athletes. Ankle sprains are the most common ankle injury in athletes and are most often treated conservatively. First-line treatment of chronic conditions such as Achilles, peroneal, or posterior tibialis tendonitis as well as stress fractures of the feet continue to be managed non-operatively. Tibiotalar impingement as well as chondral or osteochondral lesions of the ankle joint are more readily being treated with ankle arthroscopy, with good evidence-based medicine . The role of microfracture in acute ankle cartilaginous lesions and the benefits of autologous cartilage transplantation and open osteochondral transplantation are questions that are currently being investigated [72, 73, 74].
1.15 Head and Spine
Although the head and spine are often left outside the surgical scope of a sports medicine practice, these injuries are the most crucial when evaluating acute on-the-field injuries. It is estimated that nearly 70% of all sport-related deaths can be attributed to head injuries. Recent sport-related rule changes and advances in equipment have been implemented as part of the greater emphasis being placed on protecting the head, neck, and spine for contact athletes. In the National Football League, spearing and leading with the head are examples of illegal forms of tackling that have helped decrease the incidence of head and neck injuries, not only in professional athletes but at all levels of football. There is continued emphasis on protecting athletes from these catastrophic injuries through education, equipment technology, and medical advances. In addition, identifying patients who are at risk of spine and spinal cord injuries is imperative and questions regarding the relationship between spinal stenosis and spinal injury continue to be debated.
Over the past several years, significant knowledge has been gained in the area of concussion and the approach to return to play for athletes. The diagnosis and treatment of concussion has evolved from a rudimentary diagnosis and classification to a more sophisticated process that better protects athletes from devastating outcomes. The center for disease control estimates that there are more than 300,000 sport-related concussions each year . The advent of Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) has revolutionized the approach to concussion management, taking into consideration the somatic, cognitive, and neurobehavioral sequelae of concussion [76, 77, 78]. It has been shown that early return to play while still symptomatic from concussion-like symptoms predisposes the athlete to an increased risk of subsequent concussion and further neurological damage . The future of concussion management includes better identifying athletes at risk of a second neural injury and protecting them from further longer-lasting consequences. In addition, the utility of neurologic therapy (e.g. psychological therapy, vestibular therapy) warrants further exploration.
Much energy has been focused on the injury and repair of the articular cartilage; however, restoration of lost cartilage is not yet possible. Current research focuses on the use of smart polymers, stem cells, and gene therapy to deliver growth factors known to induce chondrogenesis. Biodegradable hydrogels are also being developed for use as an artificial matrix for tissue engineering and drug delivery. Tan et al. developed an injectable biodegradable hydrogel from chitosan and hyaluronic acid and demonstrated its in vitro potential by implanting bovine chondrocytes and showing their survival and proliferation . Cartilage imaging has expanded to include optical coherence tomography (OCT) and multi-parametric quantitative magnetic resonance imaging (MRI), both of which attempt to detect early reversible articular cartilage damage [80, 81, 82]. The continued goals of basic science, radiographic, and clinical research in the field of cartilage are to help identify the etiology of cartilage loss, improve early visualization of cartilage damage, and devise effective means to restore lost cartilage to prevent and treat osteoarthritis. Current methods of treating articular cartilage injuries include chondroplasty, microfracture, autologous chondrocyte implantation, osteochondral grafting, osteotomy to redirect weightbearing forces, and arthroplasty.
1.18 Soft-tissue Injury and Regeneration
Athletes who sustain soft-tissue injuries, such as muscle strains and ligament sprains, lose a significant amount of time in the process of recovery. Treatments geared at minimizing time lost due to injury are constantly being evaluated. A key step in muscle injury is the role of fibrosis. Blocking fibrotic factors in vitro has been shown to increase the healing time in muscle injuries [83, 84, 85]. Losartan, an angiotensin 2 receptor blocker, has been demonstrated to decrease fibrosis and increase recovery from muscle injury. A study at the University of Pittsburgh is looking at the possible clinical role of losartan following muscle injury. Use of relaxin, a peptide hormone, and decorin has also been shown to improve muscle regeneration and reduce muscle fibrosis development [86, 87, 88]. Stem cells, gene therapy, and biological adjuncts to healing are being investigated with the aim of decreasing recovery time for muscle injury and all are likely to play a future role in the management of soft-tissue injury.
1.19 Proprioception/Neuromuscular Control
Research in the area of neuromuscular control and proprioception is intended to better understand capsuloligamentous structures and the patho-etiology of joint injury. Biomechanical and neuromuscular assessments under sports-simulated environments continue to be used to determine the influence of weight distribution, muscle function, balance, flexibility, proprioception, gender, aging, and fatigue, as well as the effects of injury, surgery, and rehabilitation on joint stability. With a better understanding of the body’s mechanics and muscle function, better programs can be developed to improve performance and to minimize associated injuries . Some areas that have benefited from this research include golf [90, 91], cycling , overhead-throwing athletes , ACL injuries in females [94, 95] and training of elite members of the military, including the USA’s 101st airborne and Navy Seals.
Biologic augmentation of physiological healing attempts to harness the body’s own complex healing pathways and stimulate them supra-physiologically. Emergent technologies target the activation of signal pathways that induce healing in the form of osteoinduction, angiogenesis, and stem-cell-related migration and proliferation. The global orthobiologics market was estimated by Espicom to be worth $4.2 billion in 2007 and accounted for 13% of the $33 billion total orthopedic market. With an annual growth rate of 17%, orthobiologics is one of the fastest growing orthopedic segments.
1.21 Platelet-rich Plasma
The platelet has been shown to represent an effective carrier for biologic delivery of growth factors to promote healing. For over two decades, fibrin clots have been used to aid in healing meniscal tears, with moderate success [62, 63, 64, 65, 66]. Platelet-rich plasma (PRP) has gained recent attention as a potentially more effective vehicle to accelerate healing, as it is hypothesized to activate higher levels of growth factors than achieved by the fibrin clot. Current clinical applications include elbow tendinopathy, Achilles tendinopathy, plantar fasciitis, patellar tendinopathy, osteoarthritis, acute ligamentous injuries, acute muscle injury, total knee arthroplasty, ACL reconstruction, acute Achilles tendon rupture, rotator cuff repair, and acute articular cartilage repair [96, 97]. However, a recent double-blind randomized control trial failed to find a difference between PRP and placebo saline injection in Achilles tendonitis . Current drawbacks to the use of PRP is the limited basic science research devoted to its use and its cost. Further research is necessary to determine ideal levels of platelet activation, growth factor titers, and delivery methods, thus making the product more cost effective for regular use, as well as clinical studies that effectively evaluate PRP and other platelet-derived therapies. Other biologics, such as bone morphogenic protein, osteoprotegerin, and metalloproteinase inhibitors, are also being studied regarding their effective application in sports medicine.
1.22 Tissue Regeneration/Stem Cells
The final frontier of tissue engineering is the use of stem cells and the induction of progenitor cell differentiation into the necessary tissue. Adult stem cells can be obtained from a variety of tissues, including adipose , periosteum , synovial membrane , pericytes , blood , bone marrow , and skeletal muscle [105, 106]. Although sensationalized by popular culture and the non-scientific media, stem cells are expected to play a role in the healing response to sports injuries. While most of the current research in stem cells is in its early stages, clinical studies have found good results in applications such as bone-tunnel healing in ACL surgery, healing of avascular necrosis lesions, and uniting fracture non-unions. The anticipated role of stem cells is to aid in the growth and repair of cartilage, improve the correction of bony defects as well as ligament and softtissue repair, and ultimately, to support regrowth of lost native tissue.
The use of plain radiographs and high-resolution MRI continue to be the primary means by which imaging aids in the diagnosis of sports-related injuries. Nuclear imaging is being used to evaluate early arthritis that may not be appreciated on plain radiography and MRI. It can also serve to rule out atypical bony processes and thus to narrow the differential diagnosis for the surgeon. Three-dimensional CT scans can serve as a guide for bony landmarks and anatomic variation. The technique has been found useful in better delineating bone tunnels in revision cruciate ligament surgery, thereby providing a blueprint for the surgeon to plan and execute the operation. High speed bi-planar radiographs combined with MRI and/or CT scans have allowed for the determination of both contact paths of in vivo joint kinematics and cartilage thickness [107, 108, 109, 110, 111]. This technology is being used to study tibiofemoral contact patterns in lateral meniscus tears, contact paths in PCL-deficient knees, scapular kinematics, double-bundle vs. single-bundle ACL reconstruction kinematics, tibiofemoral joint congruency after medial meniscal root tears, and spinal fusions motion, and can be applied to many other situations. The ability to measure in vivo kinematics will allow us to better evaluate reconstruction techniques and result in a more precise evaluation of short- and long-term outcomes as well as a reduction in the incidence of post-traumatic arthritis.
The practice and administration of sports medicine has significantly evolved over the last few decades. Advances in the non-operative and operative management of common injuries have increased our ability to care for patients, and active individuals of all ages are returning to their pre-injury activities at higher levels. Current controversy remains in diagnostic modalities, treatment algorithms, surgical techniques, surgical indications, biologic adjuncts, and return to play guidelines. The task for the sports orthopedic specialist is to answer these challenges and to resolve existing controversy through translational research and evidence based medicine in order to better serve our patients.
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