Risk factors and prognostic indicators for Shin splints.

Risk factors and prognostic indicators for medial tibial stress syndrome.
Moen, M., Bongers, T., Bakker, E., Zimmermann, W., Weir, A., Tol, J. and Backx, F.
Scandinavian Journal of Medicine & Science in Sports, 2012; 22: 34 – 39. 
http://www.ncbi.nlm.nih.gov/pubmed/20561280

Medial tibial stress syndrome, so called ‘Shin Splints’, is a very common overuse lower leg injury observed in running population. MTSS was thought to be due to a traction induced periostitis, though recent evidence rather suggest bony overload. One of the keys to treat MTSS is to identify risk factors. Although several studies investigated risk factors for shin splints, findings seem somehow conflicting. Therefore, this study aimed at assessing risk factors for MTSS and identifying prognostic indicators to predict the duration of recovery.

In total, 35 male recruits participated in this study, 15 subjects and 20 control subjects. For the risk factor analysis, the following parameters were investigated: hip internal and external ranges of motion, knee flexion and extension, dorsal and plantar ankle flexion, hallux flexion and extension, subtalar eversion and inversion, maximal calf girth, lean calf girth, standing foot angle and navicular drop test. 
Authors found that increased ankle plantar flexion, decreased internal hip range of motion and a positive navicular drop test were significantly associated with MTSS. In regards to prognostic factors, a higher BMI was shown to be a prognostic indicator for a longer time to full recovery. All other prognostic indicators such as a previous duration of symptoms, functional activity score, the symptom-free running distance at baseline, increased ankle plantar flexion, decreased internal range of hip motion and positive navicular drop test were not associated with time to recovery. 
Authors found decreased hip IR ROM to be significantly associated with MTSS which is in contrary to other study by Burne et al. (2004). They explain that possibly both decreased and increased hip IR may cause specific way of running which potentially place increased load on the posteromedial border of the tibia. 
Increased ankle plantar flexion was another significant risk factor. Authors believe that it could lead to more forefoot landing pattern during running and back it up with the in vivo study showing that this pattern places increased load on the posteromedial border of the tibia compared to heel landing pattern. It seems somehow in contrast to current believes in regards to relationship between landing technique and MTSS therefore it should be interpreted with caution. 
Finally, higher BMI was associated with longer recovery time. It could be explained by increased bending of the tibia when more load (weight) is applied to the tibia causing microfractures and microdamage to the cortex.

There is still need for more high quality prospective studies with large cohorts to provide clear statements regarding true risk factors for the MTSS.

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