Description

• The term medial tibial stress syndrome (MTSS) is currently preferred to “shin splints.” MTSS is aching pain along the inner edge of the tibial shaft that develops when the musculature and/or periosteum in the (lower) leg become irritated by repetitive activity. The condition is part of a continuum of stress-related injuries to the lower leg. MTSS does not encompass pain from ischemia (compartment syndrome) or stress fractures.
• Tendonitis/periostitis of the medial soleus muscles, anterior tibialis, and posterior tibialis muscles
• Synonyms: tibial stress reaction, anterior muscle syndrome, tibial periostitis, perimyositis, soleus syndrome, shin splints

Epidemiology

Incidence
Common, can account for between 5% and 35% of novice-running injuries; frequently occurs bilaterally (1)

Pediatric Considerations
MTSS may account for up to 31% of all overuse injuries in high school athletes.

Etiology and Pathophysiology

• Multifactorial anatomic and biomechanical factors
  • Overuse injuries causing or limited by
    • Microtrauma from repetitive motion leading to periosteal inflammation
    • Overpronation of the subtalar joint and tight gastrocnemius/soleus complex with increased eccentric loading of musculature inserting along the medial shin
    • Interosseous membrane pain
    • Periostitis
    • Tears of collagen fibers
    • Enthesopathy
  • Anatomic structures affected include
    • Flexor hallucis longus
    • Tibialis anterior
    • Tibialis posterior
    • Soleus
    • Crural fascia
• Pathogenesis: theorized to be due to (i) calf muscle traction on periosteum and (ii) persistent repetitive loading on tibia, which leads to inadequate bone remodeling with subsequent tibial cortex changes and possible microfissures causing pain without evidence of fracture or ischemia

Risk Factors

• Intrinsic (personal) risk factors
  • Greater ranges of internal and external (>65 degrees) hip rotation
  • Significant overpronation at the ankle
  • Imbalance of musculature of the ankle and foot (inversion/eversion misbalance)
  • Female gender
  • Lean calf girth
  • Femoral neck anteversion
  • Navicular drop
  • Genu varum
  • History of previous MTSS
• External (environmental) risk factors
  • Lack of physical fitness
  • Inexperienced runners—particularly those with rapid increases in mileage and inadequate prior conditioning
  • Excessive overuse or distance running, particularly on hard or inclined (crowned) surfaces
  • Prior injury
  • Equipment (shoe) failure
• Other risk factors
  • Elevated BMI
  • Lower bone mineral density
  • Tobacco use
• Those typically affected by MTSS include
  • Runners
  • Military personnel—common in recruit/boot camp
  • Gymnasts, soccer, and basketball players
  • Ballet dancers

General Prevention

• Proper technique for guided calf stretching and lower extremity strength training, although supplementary gastrocnemius and soleus stretching has no statistical significance in reducing risk of shin splints
• Rehabilitate prior injuries adequately.
• Other recommendations
  • Gait analysis and retraining, particularly for overpronation
  • Orthotic footwear inserts were found to be preventative in naval recruits.

Commonly Associated Conditions

• Rule out stress fracture and compartment syndrome: Pain often persists at rest.
• Pes planus (flat feet)