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MTSS part 1
2011 / 05 / 20 ( Fri )
題名は 「脛骨過労性骨膜炎（MTSS) 根拠に基づく医療」
Medial Tibial Stress Syndrome: Literature Review for Evidence-Based Practice
Akiko Kai, MS, LAT, ATC, CSCS
University of Nevada, Las Vegas
May 18, 2011
“My shin hurts. What do I do?” “You’ve got shin splints. You need to start icing and stretching your calves every day.” If you are a runner or soccer player, you probably have heard a conversation like this before. If you are an athletic trainer, coach or physician, chances are you’ve made recommendations similar to this to your athlete when being asked about what she or he should do to get rid of “shin splints.” The problem is that many of us do not know exactly why we recommend what we recommend. In other words, our practice is largely based on what we were taught to do, what others do, and what seems right to do. As a clinician, you have to be able to justify what you do. Otherwise, your treatment is pointless. Unfortunately, in the case of medial tibial stress syndrome (MTSS), the lack of evidence for most of the treatment options has not improved for the last few decades. Some of that is due to the lack of universal agreement on what MTSS actually is, ongoing arguments on its etiology theories, and overall lack of randomized controlled studies.
Overuse injuries to the bone and/or its peripheral musculature in the lower leg accounts for approximately 10% to 20% of all injuries in runners and 60% of all overuse injuries in the leg (Metzl, 2005). MTSS is one of the most common causes of exercise-induced leg pain in athletes and military personnel, with the reported incidence being as high as 35% in a military study (Clanton & Solcher, 1994). In the athletics, MTSS is most commonly seen in runners, soccer players, tennis players, dancers, and basketball players who experience repetitive stress to the lower leg from extensive running on hard surfaces (Metzl, 2005). Clement et al. (1981) reported that the incidence among female and male runners were 16.8% and 10.7%, respectively (Clement, Taunton, Smart, & McNicol, 1981). According to this data, approximately 1 in 9 female runners and 1 in 10 male runners suffer from this condition. Since different epidemiology studies use different definition and/or diagnostic criteria of MTSS, the actually incidence may be much higher.
Generally, the term “shin splints” has been used to describe symptoms of following pathologies: Medial Tibial Stress Syndrome (MTSS), exertional compartment syndrome, fascial hernia, tears of the interosseous membrane, periosteal avulsion, tendinitis, muscle strain, tibial and fibular stress fractures, anterior and posterior compartment syndrome, popliteal artery entrapment and periostitis (Beck, 1994). Among such a variety of conditions, the three most common pathologies clinically recognized are: MTSS, tibial stress fractures, and exertional compartment syndrome. In this review paper, MTSS, which by far has the highest prevalence in athletes, will be primarily discussed.
Currently, little evidence exists in the literature that supports the use of commonly used therapeutic interventions for the treatment of MTSS. Such interventions include cryotherapy, use of leg and foot orthotics, stretching, strengthening program, and shock-absorbing insoles. The purpose of this paper is to review the clinically relevant research that addresses the evidence of effectiveness of commonly used therapeutic interventions for the treatment of MTSS, in the hope of finding valuable information for evidence-based practice in clinical settings.
Before analyzing existing literature on treatment for MTSS, this review paper will first address the controversy surrounding the definition of this pathology. The lack of universally accepted definition of MTSS is closely related to its history of conflicting etiology theories, some of which goes back to the early 70’s. Understanding the history ofconflicting etiology theories, some of which goes back to the early 70’s. Understanding the history of etiology controversy is also important when we make an attempt to explain the “gap” between the current research and the real-world practice in clinical settings later in the discussion section. Finally, review of literature on treatment of MTSS will be followed by discussion and conclusion.
Materials and Method
For the purpose of this professional paper, the following electric databases were used: PubMed Central, Science.gov, Cochrane database, EBSCOhost, Journal of Orthopedic and Sports Medicine, and Journal of Athletic Training. This paper will also identify citations from reference sections of research papers retrieved and highlight the results of such reports that compared therapeutic interventions for treatment of MTSS.
The PEDro Scale
In this review paper, the Physiotherapy Evidenced Database (PEDro) scale is used in order to describe the quality of four selected papers (see table 1). The PEDro scale is an 11-item scale designed for rating methodological quality of randomized controlled studies (RCTs). Each satisfied item (except for item 1, which pertains to external validity) is awarded one point to the total PEDro score, ranging 0 to 10. The PEDro scale has been used to rate the quality of over 3,000 RCTs (Maher, Sherrington, Herbert, Moseley and Elkins, 2003).
Maher et al. (2003) reported on two studies that investigated the interrater reliability of ratings of each of the 11 items on the PEDro scale and the total PEDro score. Interrater reliability was then evaluated for individual ratings and consensus ratings. They concluded that the reliability of the total PEDro score, based on consensus judgments, is acceptable. It was stated that the scale appears to have sufficient reliability for use in systematic reviews of physical therapy randomized controlled trials.
Medial Tibial Stress Syndrome
Although the term “shin splints” has been used for over 40 years, the usage of this term has been discouraged for many years due to the confusion and controversy surrounding this term. Different authors have given different names and definitions. In 1913, shin splints were described as “spike soreness” (Thacker, Gilchrist, Stroup, and Kimsey, 2002). In 1974, Andrish, Bergfeld, and Walheim (1974) defined shin splints as “the syndrome of transient pain in the leg from running or hiking and should exclude stress fractures or ischemic disorders.” The American Medical Association (AMA) defines shin splints as “pain and discomfort in the leg from repetitive running on hard surfaces, a forcible use of the foot flexors; diagnosis should be limited to musculotendinous inflammation excluding fracture and ischemic disorders” (Thacker et al., 2002). This AMA definition has not been universally accepted since there still is an argument over what is included and what is not. Unfortunately, this definition by AMA is currently the only available official definition given in the literature although it is outdated and was never well accepted among clinicians or researchers.
The most common site of overuse pain in the leg is along the distal one-half to one-third of the medial border of the tibia (Beck & Ostering, 1994). Whiting defines tibial stress syndrome as “an inflammatory reaction of the deep fascial tibial attachments in response to chronic loads” (Whiting & Zernicke, 1998). Just like the term shin splints, various authors have given different definitions for MTSS (or tibial stress syndrome). Here are some of the examples: “Pain along the posteromedial border of the tibia that occurs during exercise, excluding pain from ischaemic origin or signs of stress fracture" (Yates & While, 2006), “A condition comprising periostitis or symptomatic periosteal modelling occurring in the vicinity of the junction of the middle and distal thirds of the medial border of the tibia” (Beck, 1998), “A symptom complex in athletes who experience exercise-induced pain along the distal posteromedial aspect of the tibia” (Yates, Allen & Barnes, 2003), “A periostitis at the posterior medial border of the distal tibia” (Bennett et al., 2001). The confusing terminology and the lack of agreement between clinicians and researches on what MTSS actually is (i.e., is it a pathology or just an expression of symptoms?) is largely responsible for the insufficient evidence in many aspects of research surrounding this unique pathology. The reason why there has never been a well-accepted definition of MTSS among clinicians can be predominantly explained by its conflicting etiology theories. For the purpose of this review paper, the definition by Yates and While (2006): “Pain along the posteromedial border of the tibia that occurs during exercise, excluding pain from ischaemic origin or signs of stress fracture" will best serve as the definition of MTSS.
As the name suggests, MTSS refers to the condition in which the patient experiences diffuse pain and tenderness across the posterior-medial aspect of the tibia. MTSS is believed to be the most common cause of shin pain in athletes. However, the etiology of MTSS still remains unclear. Craig published two consecutive review articles on etiology theories that had been proposed between 1974 and 2007. Between the 1970’s and early 2000’s, the available body of knowledge suggested that the pain associated with MTSS was probably due to stress microfractures in the medial tibia resulting from a chronic bone remodeling response (Craig, 2008). As for the cause of the overload, researches are inconclusive and it is certain that multiple factors are involved. As indicated in multiple studies, the soleus muscle is likely the major contributor in creation of the continuum of injury, which is indicated by inflammation of the soleus (crural) fascia and the underlying bone. Tightness of the plantar flexor muscles (the soleus) as well as fatigue and excessive pronation appear to contribute and/or accelerate development of MTSS. Table 1 summarizes main etiology theories from 1974 to 2007.
In 1994, Beck and Osternig conducted a research on the legs of fifty cadavers to identify the anatomical structures that attach to the tibia at the site of symptoms of MTSS. This was a very helpful study in understanding the etiology of this condition since they actually measured the average sites of attachment and the ranges of attachment, comparing the results to the common site of pain. Despite the fact that the posterior tibialis muscle was believed to be the major contributor to MTSS, they found that the three structures that attach at the site of symptoms most frequently were the soleus, the flexor digitorum longus, and the deep crural fascia. Among those three structures, the soleus appeared to be the major contributor to MTSS. In fact, the posterior tibialis muscle was not found to attach at the site in any of the fifty specimens. Beck further investigated the role of tight plantar flexor muscles in the development of MTSS in 1998. He argued that tight plantar flexors could cause the tibia to bend like a bow, which creates a compressive load on the posterior-medial surface of the tibia. Persistent and increasing strain on the porous bone during remodeling incites a positive feedback loop that re-stimulates remodeling, resulting in a protracted hypermetabolic state within the bone. This chronic remodeling in the cortical bone, mediated via the periosteum (with or without periosteal injury), probably represents the pathologic lesion of MTSS.
In more recent studies, the role of foot pronation in the development of MTSS has been on a spotlight. However, the findings are inconsistent between the studies. Two studies placed a focus on how the lack of endurance in plantar flexor muscles may contribute to the development of MTSS. Couture and Karlson (2002) suggested that tight and/or fatigued soleus and/or gastrocnemius muscles contribute to an increase in stress placed on the tibia, leading to a chronic bone remodeling cycle. Likewise, Madeley (2006) argued that Athletes with MTSS had significantly less endurance in plantar flexor musculature than those without. It was unclear whether the lack of endurance was the cause or an effect of MTSS.
Thus, the research evidence that is currently available regarding etiology of MTSS does not provide clear clinical practice guidelines for the prevention or treatment of this pathology. Literature suggests that excessive pronation, tightness and fatigue of the soleus muscle are primary contributors of MTSS. Studies by Bennett et al. (2001) and Yates & White (2004) both found meaningful correlation between foot pronation and the development of MTSS. However, their relative contributions in the development of MTSS must be investigated further. There is a clear indication that the chronic remodeling state of the bone and development of microfissures are mainly responsible for creation of signs and symptoms of MTSS, resulting from the tibia being overloaded by repetitive impact activities (Craig, 2008).
Diagnostic criteria of MTSS include diffuse pain during and after activity, recognizable pain on palpation of the posteromedial border of the tibia over a length of at least 5 cm, normal radiographs, and absence of neurological findings (Metzl, 2005; Moen, 2009). Clinically, pain is often described by the patient as dull, aching, or intense in advanced cases. Another important characteristic of MTSS in early stages is the pain is experienced at the beginning of exercise but resolves during exercise in most cases (Metzl, 2005). Mile swelling of the tibia may be present (Moen, 2009). Radiograph usually appears normal, but MRI or CT scan may reveal bone abnormalities (Moen, 2009). During clinical evaluation, associated risk factors need to be considered as well as history of stress injuries. The differential diagnosis of exercise-induced leg pain should include medial tibial stress syndrome, tibial stress fracture, exertional compartment syndrome, and to a lesser extent popliteal artery entrapment and nerve entrapment (Moen, 2009). Since shin pain may arise from variety of different pathologies, it is very important to recognize those conditions clinically that may display similar symptoms before the patient or athlete begins any treatment or physical therapy.
Tibial Stress Fracture
Before diagnosing MTSS, tibial stress fracture needs to be ruled out. In recent years, tibial stress fracture and MTSS have been identified as two separate entities, whereas the common belief used to be that MTSS is an early stage of tibial stress fracture. The differentiation between MTSS and stress fracture is often difficult and should be made both clinically and physically. Radiographs for stress fracture can be false negative with sensitivities as low as 26-56% (Moen, 2009). MRI and bone scintigraphy are often used upon diagnosing stress fracture. Clinically, pain is usually more localized than it is in MTSS, which often presents with diffuse pain. Pain on percussion and pain at night are also characteristics of stress fracture (Moen, 2009).
Exertional Compartment Syndrome
Exertional compartment syndrome (ECS) is a condition in which an elevated intracompartmental pressure from exercising causes ischemia of involved muscles, represented by exercise-induced shin pain and swelling that cease when the activity is stopped (Metzl, 2005). Among the four compartments in the lower leg, the anterior compartment is involved in 80% of ECS cases. Unlike MTSS or stress fracture, physical exam and imaging tests appear normal. The gold standard for diagnosing ECS is the compartment pressure study, which involves inserting a large-bore needle into the affected muscular compartment.
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