Pathomechanism: In running phase, heel strike occurs in relative supination, with pronation of the foot increasing until midstance. Since soleus is the primary plantarflexor and invertor of the foot, medial portion of this muscle contracts eccentrically as the foot pronates.The repetitive eccentric contraction that occurs in hyperpronating athletes may explain the increased incidence of MTSS observed in such athletes. In addition, hyperpronation is a compensatory mechanism that occur in patients with hindfoot and forefoot varus, tibia vara, tight Achilles tendon, and tight gastrocnemius and soleus muscles, therefore such patients also are at increased risk for developing MTSS.
Synonym: Shin splits, medial tibial syndrome, MTSS, tibial stress syndrome, posterior tibial syndrome, soleus syndrome, periostitis.
“Shin splits” or overuse pain, describes nonspecific posteromedial leg pain, commonly as MTSS with a wide variety of other lower leg pain conditions, including chronic ECS, fascial hernia, muscle strains, periostitis, and stress fractures.
· Vulnerable patients: runners, jumping activities such as basketball and volleyball players.
· It is the commonest cause of chronic leg pain.
· Causative factors: Both biologic and biomechanical factors have been reported as possible causes of MTSS.
· Source: Tibialis posterior muscle historically has been called the source, but study revealed tibialis posterior musclebeing more lateral, indicating less likely source of MTSS. Other recent studies showed soleus, flexor digitorum longus (FDL), and crural fascia as sources of the pain. More specifically, a three-phase bone scan study demonstrated low-grade uptake along a diffuse region of the posteromedial tibia, suggesting that the condition is related to the soleus muscle.
· The most common complaint is a recurring, dull ache localized over the distal one-third posteromedial cortex of the tibia.
· MTSS occur late in the sport season after prolonged activity, whereas stress fractures tend to occur early in an athletic season as stresses increase rapidly.
· Early in the development phase, patients may experience pain at the beginning of a workout or run but feel a relief of symptoms with continued activity, followed by recurrence of pain either at the conclusion of the activity or some time afterward. Pain is alleviated with rest and generally does not occur at night. However, as this condition progresses, pain may occur throughout training or during low activity, such as walking, and possibly may continue during rest.
The pathognomonic sign is palpable tendernessalong the posteromedial edge of the distal one third of the tibia. Rarely, erythema or localized swelling over the medial tibia also may be observed. Hypermobile pronating feet are at increased risk of MTSS, hence evaluation for foot pronation or subtalar varus is recommended. Abnormal pulse, diffuse swelling, firm compartments, neurologic deficits, and vibratory pain are not associated with this syndrome.
· Xray: usually are normal in patients but is recommended to rule out abnormalities associated with other conditions such as stress fractures and tumors.
· Three-phasebone scan: to rule out stress fractures if a conservative treatment program does not alleviate pain. It is a valuable diagnostic tool used to differentiate between MTSS and stress fractures, because each condition has a distinct scintigraphic pattern. A bone scan demonstrating a longitudinal and diffuse pattern in the distal one third of the tibia is indicative of MTSS. In general, only delayed images are positive in cases of MTSS, whereas both early and delayed images demonstrate uptake in cases of stress fracture.
· Magnetic resonance imaging (MRI) : another diagnostic tool for MTSS recommended by some authors. However, MRI has a limited role in the evaluation of MTSS because of its higher cost compared with other imaging options and its difficulty in delineating MTSS from stress fractures.
· The recommended management of MTSS is multimodal, consisting of rest, nonsteroidal anti-inflammatory drugs (NSAIDs), and ice.
· Physical therapy modalities such as iontophoresis and ultrasound also may be used.Initially, rest or a decrease in training for 2 to 3 weeks is suggested and may be curative without further workup. Cardiovascular conditioning may be maintained during this period with swimming, upper body weightlifting, and deep-water running. Stationary biking is another option but should be performed with the heel on the pedal, a precaution that will diminish muscular stress transmission to the leg.
· NSAIDs often are prescribed to relieve pain and to decrease possible inflammation.
· Ice may be used to further reduce swelling and inflammation
· Addressing biomechanical abnormalities is also recommended. For example, excessive pronation may be corrected with the use of custom or off-the-shelf orthotics. Physical therapy modalities, including massage, electrical stimulation, iontophoresis, and ultrasound also have been used. If pain is present with walking or at rest, range-of-motion boots and/or walkers are used. In rare cases, crutches may be necessary.
· If the patient has not experienced pain during conservative treatment, a gradual return to training may be initiated. Warm-up and cool-down routines, including stretching, are advised with each workout to prevent recurrence of symptoms. If the patient remains asymptomatic, progression of training is recommended at increments of 10% to 25% for 3 to 6 weeks. If symptoms return, activity should cease for at least 2 weeks before training is resumed at a lower intensity and duration.
Fasciotomies of the posterior compartments of the tibia are possible treatment options in patients with intractable MTSS. In these rare cases, fasciotomies may alleviate the pull of the soleus and deep compartment muscles on the corresponding fascial insertions. However, conservative management alone has been successful in treating MTSS cases, eliminating the need for surgical intervention.
MTSS pain may subside during workout but will recur following cessation of activity. Conversely, pain associated with chronic ECS and PAES does not subside during activity and tends to remain until activity is completed.
Pain is localized to the distal one third of the tibia in MTSS but is usually more proximal in the typical stress fracture.
Ref: Baxter’s The Foot and Ankle in Sport, 2nd ed