Shin splints or Medial tibial stress syndrome is an overuse injury or repetitive stress injury of the shin area [tibial bone]. These affect persons who engage in running and jumping. It affects about 15% of all running-related injuries.
It is most often found in runners, and persons playing other sports like football, basketball, soccer, and dancers.
Untreated there is a risk of progression to stress fracture and the risk of progression is 1.5 to 3.5 times more in women.
The shin pain can be felt during or after strenuous activity, particularly running, or sports with sudden stops and starts, such as basketball and tennis.
Pathophysiology and Causes of Shin Splints
While the exact cause is unknown, shin splints are thought to be due to overloading of the lower leg resulting in an increase in stress on the tibia.
A spectrum of tibial stress injuries has been suggested to be responsible for shin splints – tendinopathy, periostitis, periosteal remodeling, and stress reaction of the tibia.
Other causes implicated are dysfunction of the tibialis posterior muscle, tibialis anterior muscle, and soleus muscle.
The pain associated with shin splints is caused by a disruption of Sharpey’s fibers that connect the medial soleus fascia through the periosteum of the tibia where it inserts into the bone.
With the repetitive impact, the soleus fatigues and create repeated tibial bending or bowing which contributes to shin splints.
A sudden increase in intensity or frequency of training fatigues muscles too quickly to properly help absorb shock.
Two kinds of factors are recognized in the causation of shin splints. One is related to patient and other is related to training.
Females have been found to be more at risk for progression to stress fractures. Female athlete triad of osteoporosis, amenorrhea, and disordered eating is thought to be responsible for increased risk of progression to stress fractures.
Patient-Related Factors
- Muscle imbalance
- Weak core muscles
- Tightness of gastrocnemius, soleus, and plantar muscles such as the flexor digitorum longus
- Knee abnormalities like genu varum or valgus
- Tibial torsion
- Femoral anteversion
- Foot arch abnormalities
- Leg-length discrepancy
- Hyperpronation of the subtalar joint
- Dysfunction of the spine, sacroiliac joint, and pelvis
Training Related Factors
- A sudden increase in intensity [pace or duration] of training
- Sudden increase in the frequency of training
- Change of terrain
- Running on hard or uneven surfaces
- Poorly fitting or worn-out footwear
Clinical Presentation
Pain in the leg on exertion is the earliest symptom of shin splints. The pain is diffuse, vague and along lower two third of tibia. Initially, pain is worse at the beginning of the exercise and gradually decreases during training and within a few minutes of stopping of exercise.
But with the progression of the condition, pain may present with lesser activity and even at rest. In the case of female athletes, a high index of suspicion should be for eating disorders, nutritional deficiencies, and abnormal menses.
The medial ridge of the tibia (origin of the tibialis posterior and soleus muscles) is often tender to palpation, especially at the distal and middle tibial regions. The anterior tibia, however, is usually nontender. Neurovascular symptoms are usually absent.
Problems that may cause biomechanical abnormalities should be looked for.
Examining patient’s shoes may show generally worn-out shoes or patterns consistent with a leg-length discrepancy or other biomechanical abnormalities. Abnormal gait patterns should be evaluated with the patient walking and running, either in the office hallway or on a treadmill.
The diagnosis of Shin splints can be made on a thorough history and physical examination.
Differential Diagnoses of Shin Splints
- Stress fracture of the tibia
- Exertional compartment syndrome [Acute or Chronic]
- Peripheral vascular disease esp in older and diabetic athletes
- Muscle tears
- Fascial defects
- Neoplasms
- Effort induced venous thrombosis
- Peroneal nerve entrapment
- Popliteal artery entrapment syndrome
Lab Studies
Lab studies are not required for the diagnosis of shin splints.
Imaging
Imaging is usually not necessary for the diagnosis of MTSS. Xrays are done if the patient does not show improvement with nonoperative treatment. Usually, x-rays are negative initially but in long-term periosteal exostoses may be present.
MRI is the new gold standard to find stress fractures and has replaced the bone scan for this. MRI is also able to identify other soft tissue injuries and can show the progression of injury in the tibia.
The progression stages as noted on MRI are periosteal edema, progressive marrow involvement, and in last cortical stress fracture.
Treatment of Shin Splints
In the acute phase, rest is considered to be the most important treatment in the acute phase of shin splints. Depending upon the individual case, the rest may consist of absolute rest or relative rest with cessation of sport for prolonged periods of time (from 2 to 6 weeks.)
Crutches may be necessary for temporary non-weight bearing and rest. Severe cases might require braces.
NSAIDs are used for pain relief.
Ultrasound, pool baths, phonophoresis, electrical stimulation have not been shown to be effective.
After the acute symptoms are over, the focus is on training modification and correction of biomechanical abnormalities, if any.
Cutting the training schedule by half may improve symptoms without the need to curtail full activity.
Slope running is prohibited.
Cross training with swimming, static bicycle or treadmill may be even more beneficial
A gradual increase of training and sport-specific activities like jumping and slope running may be added but scaled back if it causes pain.
A daily regimen of stretching and strengthening exercise for leg and core muscles should be initiated. Proprioreceptive balance training is also desirable.
Good footwear is an essential part of sportsperson and one with sufficient shock-absorbing soles and insoles, reduce forces through the lower extremity and can prevent repeat episodes of shin splints.
Orthotics may be used in persons with biomechanical problems such as excessive foot pronation and flat foot.
Female athletes, if required, should be checked and put on treatment for menstrual abnormalities, nutritional deficiencies and osteoporosis [female athlete triad]. Separate medical evaluation can be sought in such cases.
Surgery
Surgery is generally not needed and is reserved for patients who do not respond to nonoperative treatment.
Posterior fasciotomy is the common procedure performed and cauterization of the posteromedial ridge of the tibia may be added.
Surgery may improve pain and function but complete resolution may not occur.
Prevention of Shin Splints
Following precautions should be taken for prevention of shin splints
- Use good footwear running shoes with proper shock absorption and support
- Use insoles if you hyperpronate or have flat feet
- Do not train on a hard surface, uneven terrain
- Do not increase your training intensity suddenly. Instead build up gradually
- Avoid training on hard surfaces whenever possible
- Improving whole body strength and flexibility including core muscles
- Stretch and warm up before you work out, stretch after workouts.
- Stop if there is a pain
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