Shin Splints (Medial Tibial Stress Syndrome): Causes and Treatment

What Are Shin Splints?

"Shin splints" is a non-specific term commonly used to describe pain along the front or inner (medial) edge of the tibia (shinbone). The medical term for the most common type is medial tibial stress syndrome (MTSS) — pain along the posteromedial (inner-rear) border of the tibia.

MTSS is one of the most common overuse injuries in runners and military recruits, accounting for 6–16% of all running injuries and up to 35% of injuries in military basic training.

Anatomy and Pathophysiology

The exact cause of MTSS is debated, with two main theories:

Traction theory: Repeated traction from the soleus muscle (a calf muscle) on the periosteum (the fibrous covering of the tibia) causes periosteal stress and inflammation.

Bone stress theory: MTSS represents a continuum from normal bone stress → stress reaction → stress fracture, with MTSS being an early stage of cortical bone overload before a stress fracture develops.

Both mechanisms likely contribute, explaining why MTSS and tibial stress fractures can be difficult to distinguish clinically.

Causes and Risk Factors

MTSS is caused by doing too much, too soon — a training error:

Sudden increase in training volume or intensity
Running on hard surfaces or cambered roads
Overpronation (flat feet) — increases tibial torsion
Worn or inappropriate footwear
Poor running mechanics
Sudden return to activity after a rest period

Risk factors:

Female sex
Prior history of MTSS
Increased body mass index
Overpronation/flat feet
High weekly training mileage
Inadequate bone density (low calcium/vitamin D)

Symptoms

Classic presentation:

Diffuse, aching pain along the inner border of the shin (posterior-medial tibia)
Pain begins with the start of exercise, may improve as muscles warm up, and returns after exercise
Tenderness on palpation along a broad area of the posteromedial tibial border (>5 cm)
Pain improved with rest

Important distinction from stress fracture:

Stress fracture pain: Point tenderness at one specific spot; pain present at rest; does not improve with warm-up
MTSS pain: Diffuse tenderness over a broad area; typically improves with warm-up

Diagnosis

MTSS is primarily a clinical diagnosis:

History and physical examination
X-ray: Usually normal; may rule out other pathology
MRI: If stress fracture must be excluded; MTSS shows periosteal edema without cortical break

Treatment

Active Rest and Load Reduction

Reduce running volume by 50% or more — or switch entirely to low-impact cross training
Running through severe MTSS risks progression to stress fracture
Maintain fitness with pool running, cycling, swimming, or elliptical

Addressing Contributing Factors

Footwear: Replace worn shoes; consider motion-control or stability shoes if overpronating
Orthotics: Custom or prefabricated insoles for overpronation
Running mechanics: Gait analysis; increasing cadence (steps per minute) reduces tibial loading per step
Surface: Run on softer surfaces during recovery

Symptom Management

Ice massage (20 minutes after activity)
NSAIDs for acute pain management
Calf stretching and strengthening
Physical therapy: Lower leg strengthening, hip strengthening, gait retraining

Return to Running

Gradual progressive return to running using a structured protocol
Pain-free cross-training maintained throughout
Monitor for pain with each running session — increase only if pain-free
Typical return: 4–8 weeks

Prevention

Follow the 10% rule for increasing training volume
Incorporate rest days
Maintain adequate calcium and vitamin D intake
Address biomechanical issues proactively (gait analysis before developing injury)
Strength train: Hip and calf strengthening reduces tibial loading