Medial tibial stress syndrome (MTSS), also known as shin splints, describes a spectrum of stress injury that occurs at the medial tibia. This term is often used to indicate any type of tibial stress injury or the earlier manifestations of a tibial stress lesion before a fracture component can be identified 1. It is considered a low risk stress fracture.
Typically occurs in athletes (e.g. runners/jumpers) and is characterized by localized pain that occurs during exercise at the medial surface of the distal two-thirds of the tibial shaft.
A "one-leg hop test" is a functional test, that can be used to distinguish between MTSS and a stress fracture: a patient with MTSS can hop at least 10 times on the affected leg where a patient with a stress fracture cannot hop without severe pain 2.
CT is not particularly sensitive (~40%) 3. It may reveal mild osteopenia as an early sign of fatigue damage of cortical bone in tibial diaphysis 3,4.
MRI is the most sensitive radiological examination (~88%) 3. It may demonstrate a spectrum of findings ranging from normal to periosteal fluid to marrow edema to actual stress fracture 5. The medial cortex (+/- posterior cortex) is most commonly affected 3.
These findings are graded using the modified Fredericson classification system which allows grading of the MRI findings with a good correlation with clinical severity and outcome. It allows an estimate to a safe return to activity in athletes. It is as follows 7,8:
- grade 1: periosteal edema only
- grade 2: bone marrow edema appreciated only on T2-weighted sequences
- grade 3: bone marrow edema appreciated on both T1 and T2-weighted sequences
- 4a: multiple discrete areas of intracortical signal changes
- 4b: linear area(s) of intracortical signal change correlating with a frank stress fracture
Bone scintigraphy is relatively sensitive (~75%) 3 and may demonstrate high uptake in the affected region, characteristically along the posterior tibial aspect on lateral views.
- tibial stress fracture: there can be some overlap depending on the definition.
- 1. Bergman AG, Fredericson M, Ho C et-al. Asymptomatic tibial stress reactions: MRI detection and clinical follow-up in distance runners. AJR Am J Roentgenol. 2004;183 (3): 635-8. AJR Am J Roentgenol (full text) - Pubmed citation
- 2. Batt ME, Ugalde V, Anderson MW et-al. A prospective controlled study of diagnostic imaging for acute shin splints. Med Sci Sports Exerc. 1998;30 (11): 1564-71. Med Sci Sports Exerc (link) - Pubmed citation
- 3. Gaeta M, Minutoli F, Scribano E et-al. CT and MR imaging findings in athletes with early tibial stress injuries: comparison with bone scintigraphy findings and emphasis on cortical abnormalities. Radiology. 2005;235 (2): 553-61. doi:10.1148/radiol.2352040406 - Pubmed citation
- 4. Gaeta M, Minutoli F, Vinci S et-al. High-resolution CT grading of tibial stress reactions in distance runners. AJR Am J Roentgenol. 2006;187 (3): 789-93. doi:10.2214/AJR.05.0303 - Pubmed citation
- 5. Anderson MW, Ugalde V, Batt M et-al. Shin splints: MR appearance in a preliminary study. Radiology. 1997;204 (1): 177-80. Radiology (abstract) - Pubmed citation
- 6. Gaeta M, Minutoli F, Mazziotti S et-al. Diagnostic imaging in athletes with chronic lower leg pain. AJR Am J Roentgenol. 2008;191 (5): 1412-9. doi:10.2214/AJR.07.3379 - Pubmed citation
- 7. Kijowski R, Choi J, Shinki K et-al. Validation of MRI classification system for tibial stress injuries. AJR Am J Roentgenol. 2012;198 (4): 878-84. doi:10.2214/AJR.11.6826 - Pubmed citation
- 8. Marshall RA, Mandell JC, Weaver MJ, Ferrone M, Sodickson A, Khurana B. Imaging Features and Management of Stress, Atypical, and Pathologic Fractures. (2018) Radiographics : a review publication of the Radiological Society of North America, Inc. 38 (7): 2173-2192. doi:10.1148/rg.2018180073 - Pubmed