Medial tibial stress syndrome

Medial tibial stress syndrome (MTSS) is one of the most common causes of exercise related leg pain (5,38). Originally coined by Drez and reported by Mubarak et al. in 1982 (31), the term describes a specific overuse injury producing increasing pain along the posteromedial aspect of the distal two-thirds of the tibia (27,31). Although runners are most commonly afflicted, with one study reporting a 13% incidence (14), individuals involved in jumping activities may also develop this disorder (13). The term “shin splints” is frequently used synonymously with this disorder (29,38); however, as advocated previously (5,13,25), this term should be abandoned, and MTSS used instead, since it more aptly describes the location and presumptive etiology of this disorder. HISTORY/TERMINOLOGY In 1958 Devas initially suggested tibial stress fractures as a cause of shin soreness (17), and stress fractures are now characterized as a very common cause of exertional leg pain. In addition, over the past decades several other causes for this pain have been characterized. These include chronic compartment syndromes (most frequently of the anterior and deep posterior compartments), entrapment of arteries (popliteal or external iliac) or nerves (superficial peroneal nerve), deep vein thromboses, rupture of the gastrocnemius muscle, fascial herniations, and muscle strains (38). Simple muscle strains are probably the most common cause of acute exercise induced leg pain, while more subacute or chronic pain may be caused by stress fractures or chronic (exertional) compartment syndrome (CCS) (13). Patients with exertional medial tibia pain remain a diagnostic challenge. Although progress has been made over the past several decades and rational etiologic theories exist, there continues to be considerable confusion and controversy regarding the most appropriate terminology to be applied to these patients. This is most likely because neither a specific pathologic mechanism nor a discrete pathologic abnormality has been identified in these patients. Although this review includes several well controlled studies completed recently, the reader should realize that this review is based primarily on collected case studies, expert opinion, and theory. Over the past 30 years many appellations have been introduced, including generic terms such as “medial tibial stress syndrome,” “medial tibial syndrome,” “tibial stress syndrome,” and “shin splints” (15,31,33,40), as well as terms meant to infer a specific anatomic or pathologic aberration, such as “posterior tibial syndrome,” “soleus syndrome,” and “periostitis” (22,29,31). Of all these terms, medial tibial stress syndrome is the most appropriate (5,13,25) since there are distinct drawbacks to each of the others that are addressed in this review. Shin splints has been the most problematic term since it is the least descriptive and thus the most confusing. While most authors recommend dropping it from the medical lexicon (5,13,25), others have advocated its continued use (9). Although the specific origins of the term are not precisely known, it was apparently originally a lay term that became a medical diagnosis through common usage (40). Since it had no formal definition, and thus was used rather imprecisely by both the public and the sports community (40), a subcommittee of the American Medical Association (AMA) was tasked with formulating a definition. In 1966 the AMA publication The Standard Nomenclature of Athletic Injuries defined shin splints as a “pain or discomfort in the leg from repetitive running on hard surfaces or forcible, excessive use of the foot flexors; diagnosis should be limited to musculotendinous inflammations, excluding fracture or ischemic disorder” (34,40). Slocum commented over 30 years ago that in light of this rather specific definition shin splints should no longer be considered a catchall diagnosis for any condition causing pain in the lower leg after exertion (40). Despite this admonition, shin splints continues to be used to describe almost any type of exertional leg pain. As recently as 1995, shin splints was defined as inclusive of chronic compartment syndrome and stress fracture (3), and more recently, it was noted to be “a nonspecific term used to describe exertional lower leg pain from almost any cause” (4). This continued confusion most certainly persists since shin splints does not implicitly refer to any specific location or infer an etiology for the pain associated with this syndrome. Since the AMA definition does not explicitly specify any particular location, some authors have limited the location of pain to the distal medial tibia (11,22,31,33,43,45), while others include patients with either medial or proximal anterolateral tibia pain (2,8,9,40). Due to dissatisfaction with the term shin splints, several other terms have been suggested. These include “medial tibial syndrome,” “tibial stress syndrome,” “posterior tibial syndrome,” “soleus syndrome,” and “periostitis.” While these terms may arguably be an improvement, each has its limitations, either because of inadequate supportive evidence or because of possible misinterpretation of the terminology as initially reported. Puranen introduced medial tibial syndrome (32) in 1974, after noting excellent results in 11 patients with chronic exertional medial tibia pain who had had a posteromedial fasciotomy. From these observations he suggested that the pain resulted from ischemia of the deep flexor compartment muscles during prolonged exercise. However, subsequent studies (31,45) in similar patients have not demonstrated abnormal compartment pressure elevations. In the same year Clement (14) theorized that tibial stress syndrome was the clinical prologue to the development of a stress fracture. He hypothesized that during exercise the shock absorbing function of the lower leg muscles is eventually impaired secondary to muscle fatigue, resulting in greater stress transmission to the bone and an eventual stress fracture. Since the clinical presentation, response to treatment, and radiological findings of these two disorders are quite different (37), it is unlikely that chronic MTSS is a precursor to a stress fracture. As will be discussed, individuals with more acute MTSS may eventually develop a stress fracture, as suggested by Batt (9). In 1978 James et al. (23), explicitly noting dissatisfaction with the imprecise, nonspecific meaning of shin splints, suggested posterior tibial syndrome as an alternative, since the origin of the tibialis posterior muscle was thought to be the source of the pain. This is unlikely, however, since subsequent anatomic studies (11,29) have demonstrated that this muscle has a more lateral tibial origin. Several years later, the term “soleus syndrome” was proposed (29). These authors had noted a distinctive pattern of increased uptake on triple phase radionuclide bone scan in individuals with characteristic exercise induced medial leg pain. The location of the uptake appeared to coincide with the origin of the medial soleus muscle. However, this terminology is probably too specific, since more recent anatomic studies have not been able to exclude other deep flexor compartment muscles from consideration (11,18). Finally, when Mubarak et al. (31) initially introduced Drezs’ term, they suggested periostitis as the essential etiology of MTSS, which was subsequently supported by several authors (5,13,27). This term is probably inaccurate as well since scintigraphic and biopsy studies indicate that this disorder is probably not an inflammatory process of the periosteum (2,4,9,16,24,31,33). In fact, while a true inflammatory process would demonstrate increased uptake on the first two phases (angiogram and blood pool) of a triple phase bone scan (20,21), the most frequent finding in these patients is diffuse uptake on only the delayed (third) phase of the scan (22,29,37). This finding is more indicative of bone remodeling (20). In addition, several studies have reported the results of pathologic examinations of periosteum, fascia, and bone biopsied at the time of fasciotomy in recalcitrant cases of MTSS (2,16,24,29,31,33). These studies represent a total of over 75 biopsy samples. Of all these specimens only four have documented evidence of periostitis (2,29,31). Of note, a substantial number (22 of 75) of these biopsies demonstrate evidence of fascial inflammation, most commonly of the crural fascia (31,33), and an equal number show increased vascular ingrowth, increased numbers of osteoblasts, and osteoid, indicative of enhanced bone metabolism (24 of 75). Further confusing the terminology, in 1986 Detmer proposed a tripartite classification system for chronic MTSS (14). According to this schema, stress fractures or bone stress reactions are categorized as a type I lesion, periostalgia caused by avulsion of the tibial periosteum near the fascial insertion of the soleus is a type II lesion, and chronic compartment syndrome of the deep posterior compartment is a type III lesion. As noted by Clanton (13), however, this is only a clinical stratagem since each of these disorders may be differentiated with a thorough clinical evaluation and appropriate laboratory studies (7,13). It is also interesting to note that while Detmer noted periosteal avulsion with adipose tissue interposed between the bone and periosteum at fasciotomy in a majority of his patients with the Type II disorder, these findings have not been replicated in any previous or subsequent studies. Finally, although not explicitly mentioned, this system may cause further confusion since it tends to imply a progression in severity of a single pathophysiological mechanism despite any supportive evidence to this effect. Thus this schema is not recommended (13) and is not generally used. As discussed above, there are problems with each of the aforementioned terms that preclude any particular one being used exclusively for this disorder. However, a single terminology to describe this would be extremely helpful in further defining the specific characteristics of this group of patients, as well as for performing multistudy analysis (9). This would aid in the determination of predisposing risk factors, the efficacy of different treatment regimens, and hopefully the identification of the etiological mechanism and the specific pathologic abnormality. While MTSS may not be the perfect terminology, it is the most appropriate term for these patients at the present time, since it describes the location and probable pathophysiology of this disorder. EPIDEMIOLOGY Because of the varied and inconsistent terminology, it has been difficult to determine a precise incidence or frequency for MTSS. In a short-term prospective study, Andrish et al. (6) reported an incidence of 4.1% during a summer training program for students entering the U.S. Naval Academy, while Clement et al. (15) in a retrospective review identified 239 cases out of 1819 total injuries (1650 patients) for an incidence of 13.2%. As previously noted, runners are most commonly afflicted, although individuals involved in jumping activities, such as basketball, volleyball, or long jumping, may also develop MTSS (5,13). In addition, there does not appear to be any predilection to one gender versus the other. ETIOLOGY While neither the precise pathophysiologic mechanism nor the specific pathologic lesion in MTSS is known, the anatomic site of the abnormality has been fairly well localized. Initial conjecture, as noted previously, implicated the tibialis posterior muscle; however, recent information has identified the fascial insertion of the medial soleus as the most probable source (11,29). As previously described, Holder and Michael (22) reported a characteristic abnormality on triple phase bone scan in several patients with complaints of chronic (mean 12.6 months) posteromedial tibia pain. Specifically, these subjects demonstrated low grade uptake of the radiotracer along a diffuse region of the posteromedial tibia only on the delayed phase of the scan. Subsequent anatomic dissections on cadavers, as well as EMG and muscle stimulation studies by this same group, provided further confirmatory evidence that this area of uptake coincided with the origin of the medial soleus muscle, and its deep fascial insertion, termed the “soleus bridge” (29). Beck and Osternig (11) examined the tibial attachment sites of the soleus, flexor digitorum longus, and tibialis posterior muscles, as well as the deep crural fascia in 50 cadaver legs. They found that while the insertions of the soleus muscle and the deep crural fascia were most consistently attached to the posteromedial aspect of the distal two-thirds of the tibia, consistent with the previous findings, the flexor digitorum longus (FDL) muscle was also noted to insert in this region although less frequently. These authors considered the tibialis posterior muscle a less likely source since its origin tended to be located more laterally on the tibia. Thus, while it appears that the origin of the medial soleus is the most likely source of pain in these patients, the FDL cannot be excluded. While running, the foot initially makes contact with the ground in a relatively supinated position and moves into a relatively more pronated posture as the foot progresses through the stance phase. Since the soleus is the and of the foot Michael and Holder theorized that the medial of this muscle as the foot moves from to (29). this results in increased stress of the fascial origin of the medial soleus, the that through the periosteum to insert in the bone of the tibia This the most well regarding the etiology of MTSS Although the FDL has also been implicated as a possible source of pain because of its anatomic location, it is not or this muscle is should be made between acute and chronic MTSS (9). The pathophysiology of individuals characteristic after a to such as in a are most different from the or or after several years of It has been theorized that individuals with relatively acute may in at least two (9). is with of the appropriate of the fascial and bone may despite the continued an inadequate or of these resulting from excessive stress or may in a stress fracture, or (9). from a recent study that subjects with characteristic exertional medial tibia pain appears to this theory. These authors reported that individuals with relatively (mean months) were more likely to have abnormal findings with more chronic (mean Although the precise pathologic abnormality has not been it appears to a stress by the crural fascia or bone along the posteromedial of the tibia and probably not the periosteum It is that there is both fascial and bone and as suggested by Batt some may on to develop a while others may develop a stress fracture. This however, probably does not the pathophysiology of the chronic disorder. It should also be that these individuals may present with two disorders such as MTSS and chronic compartment syndrome In addition, a disorder may from an in resulting from pain from the observations have noted excessive foot to be a risk for MTSS, and this has been supported by several and examined patients with a of MTSS, as well as runners with and found that the individuals with MTSS have a greater of the These individuals also had greater as and also a group of individuals with MTSS with a group of subjects as well as with such as leg of and and leg While they also noted that was in the subjects with MTSS, the of was more in these study has also found more and in a group of these as well as evidence of a greater of foot The most common in these patients is a pain along the or distal posteromedial tibia in this the pain may at the of a with continued only to the or after a the pain may only be noted the of a this the pain with continued training the pain may more and (5,13,27). Patients may of only to have the pain with of increasing the pain may be present with or at (5,13,27). of or ischemic pain are not present either during or after exercise. have been reported to be in of these cases commonly after a relatively in the or of training of over of training as well as in training or out have also been implicated Patients with either stress fracture or chronic compartment syndrome (CCS) present however, there may be considerable with stress fractures most commonly of the of pain and of a very region of the tibia that with continued training the pain may be the and pain may be present as with develop a and discomfort of the muscles of the involved compartment after running for a or pain relatively after exercise These patients may also note a or of the distal in the region of of the the involved compartment In with MTSS there is a diffuse region of along the posteromedial of the tibia this the and distal of the tibia, from proximal to the medial to proximal there is or of this same or pain with of the tibia less consistent finding in patients with MTSS is discomfort with or of the of this muscle group may be with the (23), or and stress may be with a (14). findings in MTSS, stress fracture, and chronic compartment for MTSS or stress findings should be with the findings of a stress fracture in which there is a discrete location of with there is well pain at this same site with as well as with from that individuals with chronic compartment syndrome have a and discomfort may only be by performing the the muscles of the involved compartment may the pain. muscle or in the area to the the compartment may be The is in patients with MTSS as well as in with stress fractures or chronic compartment syndrome as noted evaluation for foot or should also be may be in the position on the and reported greater in subjects with MTSS with However, study reported that was the of for both and foot between the medial and the less has also been associated with MTSS (40). of as noted may be more of MTSS although they as well as in patients with MTSS are almost as there is posterior noted, consistent with a periosteal to the increased repetitive stress such as periosteal or are a tibial stress fracture should be out with a bone or a scan (5,13). laboratory findings in MTSS, stress fracture, and triple phase bone scan is in MTSS from a stress fracture and the diagnosis when the diffuse region of uptake is noted along the posteromedial aspect of the tibia only on the delayed phase of the scan Medial and lateral are suggested to the region of uptake more precisely bone may more difficult phase radionuclide bone of MTSS and a tibial stress fracture for of the demonstrate a area of uptake in the distal tibia while the other leg a more diffuse low grade area of uptake consistent with recent studies have reported the use of in the evaluation of this disorder. et al. runners with lower of characteristic exertional leg pain and had bone scan evidence of MTSS, a tibial stress or stress fracture. was on each leg and with the findings on bone scan. In of the the findings with the findings on However, since the findings of the patients with and bone scan findings consistent with MTSS were not differentiated from with stress or fracture, this study is not helpful in the specific findings associated with MTSS. These authors also noted diffuse to the insertion of all the deep flexor compartment et al. on patients with and findings consistent with MTSS. This group had more chronic with a of with a of in the In this study, subjects had had evidence of periosteal of the medial anterior tibia, had bone also had periosteal and two had stress for were not and only subjects had In four of the with periosteal the was noted to the insertion of the medial Since bone were not it is not similar results have been with this As previously mentioned, these authors noted an between the findings and the of As noted by the this may be an that two distinct pathophysiological are for the acute and chronic of this disorder. Initial of MTSS primarily some type of of the involved Specifically, the most commonly running, should either be or the training other pain activities should be as may be delayed on the to a although the for a stress fracture should be considered and discussed with the In addition, the should that the in running may be to the development of overuse pain is present with or at may be used to all This should be continued the is pain a such as or running, are recommended for the patients to pain with any of these activities, for with while that exercise should be it may be any running, may be the most since runners and running with should be for at least several since it may some other are including bone and however, have been demonstrated to be and have appropriate also appear to be is or may be Since MTSS appears not to be an inflammatory disorder, the use of does not appear to be While has not been demonstrated to be an in at least one study it is recommended after MTSS has should be with the as well as in a since in the position a more of the soleus muscle is noted, the should be for of medial may be for a while a may be for excessive In one recent study the use of were noted to the incidence of MTSS in a a previous study with demonstrated no the has been pain for several or light running may be The is to training at of the previous and on In addition, the should and each training and and after each training or may be increased as long as the It is generally recommended that these may be increased that the training or is in may be increased more as long as the pain however, this the of should only be increased after progression in the or are no studies this although the results are generally to be quite may also be recommended at any time during this the should for several after of the pain at a lower or or several of with running, is of the posteromedial and deep fascia of the tibia is an in patients with chronic recalcitrant that have several with This is thought to the of the soleus and the deep compartment muscles on fascial insertions (13). In addition, it has been suggested that this may in of the periosteum Detmer has reported a of greater at with his which of the tibial periosteum, while et al. reported that of patients were after fasciotomy. and should also be of that may MTSS, including and of the of running training and to an training program Although terms have been used for patients with diffuse exertional medial tibia pain, in the term “shin splints” has been most confusing. Despite being defined quite over 30 years this term continues to be used to describe any type of exertional leg pain. The term “medial tibial stress syndrome” (MTSS) is most appropriate since it most aptly describes the location, and the presumptive etiology of this disorder. The use of consistent terminology will aid in the of specific risk factors, pathophysiological diagnostic studies, and treatment of this syndrome. The etiology and of this syndrome are not however, excessive stress at the fascial insertion of the medial soleus or flexor digitorum longus muscles appears to be most This syndrome may be since the and findings in these patients are quite triple phase bone scan is in MTSS from stress fracture since each has a distinctive scintigraphic The majority of these patients to to previous of activities after a although fasciotomy may be in some recalcitrant The authors to for a review of this