Medial tibial Stress Syndrome or Shin-Splint Syndrome clinically represents exercise-induced pain in the distal third of the leg along the posteromedial border of the tibia, the leg bone.

The condition results from repeated stress injury and is often seen in sports involving running and jumping. Such activities induce pain and discomfort in the leg due to repetitive running on hard surfaces. Forcible and excessive use of the foot flexors remains the underlying cause of medial tibial stress syndrome or shin splints.

Anatomy

The leg has four muscle compartments.

1. Anterior

It contains the following muscles;

• tibialis anterior muscle; flexes the ankle upwards and inverts the foot
• extensor hallucis longus; extension of the great toe
• extensor digitorum longus; extension of other toes and aids eversion
• peroneus tertius; its function is the same as extensor digitorum longus

• Deep posterior

This compartment houses the;

• flexor digitorum longus; flexes the toes
• tibialis posterior; flexes the foot downwards and inverts the foot
• flexor hallucis longus; flexes the toes

• Superficial posterior

This compartment comprises of;

• gastrocnemius  
• soleus

 Both of these muscles are predominantly plantar flexors of the ankle.

• Lateral

This compartment contains the foot evertor muscles, the peroneus brevis, and the longus.

Causes of shin splint

Shin splint is a common sports injury and is attributed to the overuse of the muscles.

The underlying pathophysiology may include;

• Inflammation of the periosteum (a layer of connective tissue that surrounds bone) induced by fascial traction or a local bone stress reaction
• Chronic inflammation of the muscles at their attachment site along the posterior medial tibia

Some other suggested causative factors regarding shin splint include;

• A dysfunction of tibialis anterior and posterior and their area of attachment
• Muscle imbalance and inflexibility, especially tightness of the gastrocnemius, soleus, and plantaris muscles
• Muscle weakness of the triceps surae resulting in muscle fatigue, altered running mechanics, and strain on the tibia.
• Rigidity and strength discrepancy of the hamstring and quadriceps muscles

Runners, including sprinters, middle and long-distance runners, and footballers, often face such musculoskeletal injuries. The condition is also common in dancers and military recruits.

Athletic sports injuries are often related to

• Errors in training techniques
• Running too fast without developing endurance
• A sudden increase in training intensity and duration with poor conditioning
• Running on a hard, irregular or rough surface
• Improper running shoes with poor shock absorption
• Biomechanical abnormalities as foot arch abnormalities, hyper-pronation of the foot, unequal leg length

Signs and symptoms of shin splint

The condition presents itself as;

• Tenderness, soreness, or pain along the inner side of the tibia, the shinbone
• The pain may affect both legs at the same time
• Mild swelling in the lower leg
• The inner side of the leg is painful to touch
• The pain of the initial stage gets relieved on stopping exercise
• The symptoms may worsen to result in stress reaction or stress fracture

The pain may initiate with exercise and resolve while exercising. It returns during the cool-down period. Worsening conditions cause pain during exercise and may be present for hours or days even after cessation of the inducing activity.

Shin splint may aggravate to result in stress fracture. Stress fracture also presents with a tenderness of the anterior tibia.

Differential Diagnosis with a stress fracture

A stress fracture is a serious injury than shin splints and is characterized by pain in the lower leg. Some of the distinguishing points between the two include;

• The pain of a stress fracture is focal and localized. There is marked tenderness in less than 5 cm area along the medial side of the leg. There is a definite spot of sharp pain. This is in contrast with shin splints.
• The pain of stress fractures is relieved in the morning; shin splints often feel worse in the mowing to all nigh rest. Shin splints pain is worse in the morning because of muscle stiffness.

Diagnosis of medial tibial pain syndrome

History and physical examination indicate the instigating event and nature of pain in shin splints. The condition is marked by;

• Exercise-induced pain along the distal two-thirds of the medial tibial border
• Pain is provoked while exercising and post-exercise and relieved with rest
• There is no cramping, burning, pressure-like calf pain, pins, and needles in the foot

Failure of conservative treatment requires an echogram of the affected area. In case of a stress fracture, black lines are visible. A triple-phase bone scan helps differentiate between a stress fracture and a medial tibial stress syndrome.

Treatment of medial tibial pain syndrome

Treatment is predominantly conservative. Surgical intervention is taken up in patients where the conservative treatment has failed for a year. Recurrence of the condition is also an indication of surgery.

The surgical procedure releases the deep posterior fascia to relieve tension or pressure. It is usually an open fasciotomy of the deep posterior compartment, the release of the soleus bridge, and the removal of a periosteal strip from the involved medial tibia.

1. Immediately after the injury to first few days (acute management)

1. RICER
2. Medication
3. TENS

The application of TENS improves circulation and enhances the nutrient supply of the affected area. Place the first pad just below the knee and the second pad further along the tibia bone.

• After the first few weeks

• Massage

Massage works to improve blood circulation in the affected area and ease away inflammation, thereby alleviating pain. Massage will help you improve your shin splint pain by improving blood circulation to the muscles attached to your shin bone.

• Therapeutic ultrasound
• Active rehabilitation

Educating the patient along with a graded loading exposure program is the initial physical therapy response.

Conservative physical therapy aims to correct function, gait, and biomechanical overload factors. A retraining protocol for runners is advised, and a graded running program is suggested as a gradual tissue-loading intervention.

Few weeks of rest with medication, cryotherapy, and passive exercise followed by analgesic gel application are taken up in the acute rehabilitation phase.

The subacute phase of rehabilitation aims to modify training conditions. For example, decreasing the running distance, intensity, and frequency.

During the rehabilitation period, the following are advised;

• low impact exercises
• cross-training exercises
• pain-free sport-specific activities and hill running
• stretching and strengthening (eccentric) calf exercise
• strengthening core and hip muscles
• Proprioceptive balance training

Some exercises for medial tibial pain syndrome include;

Gastrocnemius calf stretch

• Stand and take support by placing your hands against a wall or on the back of a chair.
• Take your right leg behind you.
• Make sure to keep your feet flat and pointed forwards.
• Keep your back heel down with your back leg straight.
• Bend the front knee as if taking a step against the wall until a stretch is felt in the leg's calf muscles at the back.
• Make sure to keep your back leg and back straight throughout the stretch.
• Hold the stretch for few 30 seconds.
• Repeat at least five times. Switch sides and do the same with the left leg.
•  Perform this stretch three times every day.

Soleus calf stretch

• Stand straight, taking support with your hands against a wall or the back of a chair.
• Take the same position as that of gastrocnemius stretch and place your foot behind you.
• Keep your feet flat.
• Bend the knee of your front leg slightly.
• Keeping your back heel down, bend the back knee. Shorten the stride if it is painful.
• Hold the stretch for few seconds. Repeat the stretch 2 or 3 times on the same leg and the opposite one as well.
• Perform the stretching three times a day.

Achilles tendon standing stretch

• Stand on a stair step, a curb, or a step stool.  Take support on a railing.
• Stand on the stair with the balls of your feet on the edge of the stair step. 
• Slowly hang the heel of one leg off the step. This will create a stretch in the calf muscles and the Achilles tendon.
• Hold the position for few seconds.
• Repeat at least three times and perform the stretch up to 5 times a day.

Seated shin stretch

This stretch helps relieve the pain in the shin area by targeting the muscles at the back of the lower leg.  

• Kneel on the floor or a yoga mat.
• Sit back on your heels. Your heels should be directly beneath your buttocks.
• Begin by placing your hands behind you on the floor.
• Lean back slightly.
• Give a gentle push on the heels using your body weight to feel a stretch in the lower leg muscles.
• You can increase the pressure or stretch intensity by lifting your bend knees off the ground in front.
• Hold for few seconds.
• Release and repeat at least three or five times.

Prevention of split shins

• Analyze your running or other sports movement and modify it under the consultation of a physical therapist.
• Avoid overdoing excessive running or other high-impact activity for too long.  
• Wear appropriate shoes and change shoes every 350-500 miles in case of running long=distance.
• Consider using arch supports, especially if you are flat-footed.
• Wear shock-absorbing insoles or orthotics.
• Lessen the impact by cross-training with a sport that places less impact on your shins, for example, swimming, walking, or biking.
• Start new activities slowly and increase training time and intensity gradually.
• Add strength training to strengthen and stabilize your legs, ankles, hips, and core muscles.
• Learn to identify triggers and risk factors and avoid them.