Medial Tibial Stress Syndrome (Shin Splints) – Treatment
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Medial tibial stress syndrome, commonly known as «shin splints», is an overload injury of the tibia (shinbone). Without appropriate load management and treatment, it often becomes a recurring problem over many years.
Medial tibial stress syndrome (MTSS) is a local overuse injury on the medial side (inside) of the distal two-thirds of the tibia. Despite popular belief, it is not an inflammatory condition of the periosteum (1), and anti-inflammatory drugs are not helpful in treating MTSS. This condition is now recognized as a bone stress injury, with a pathological process similar to that of a stress fracture.
As with any overuse injury, two therapeutic principles that should guide the treatment:
increasing load tolerance
Bone stress injuries are the result of abnormal loading of normal bone. When the bone is subjected to repetitive stresses during activity, without adequate rest, there will be a mismatch between activity in cells that absorb and produce bone matrix (osteoclasts and osteoblasts). This allows for microscopic lesions to build up inside the cortical bone, and for the bone to become less resilient to continued stress (2).
Load management is an integral part in the management of MTSS, both to prevent further development of the condition and to allow for the cortical bone to heal. This can be done in several ways:
reducing workout intensity
cross-training (choosing different ways to exercise)
Although the total stress on the tibia should be reduced as part of the rehabilitation process, it is generally recommended to maintain some level of loading. If you rest until pain has resolved, little has been done to improve the tibia's load tolerance, and the pain will easily return when the athlete resumes training (3).
Increasing load tolerance
Athletes with long-term symptoms of MTSS have significantly lower BMD than athletes and non-athletes without MTSS, but only in the painful area of the tibia (4), and BMD is normalized once the symptoms have resolved (5).
Knowing that tibial cross sectional area (CSA), diameter and bone mineral density (BMD) all affect the tibia's load tolerance (6), and that long-standing symptoms of MTSS seem to resolve with increases in BMD, makes it clear why measures to increase BMD and CSA are considered central to the treatment of MTSS.
In right amounts, running can have a positive impact on bone and lead to increased BMD (7-9). Graded running programs have long been an important part in treating MTSS, with the aim of increasing load tolerance (10).
The illustration shows different bone cross-sectional onlinethe Tibial cross-sectional area (CSA) between a recreational runner (left) and an elite runner (right) of the same sex and age, both without MTSS. The CSA of the bone on the right is 25% larger than the left. Based on Hart et al. 2017 (6). Illustration by: Ken Fredin.
A running program should be individually tailored based on the athlete's symptoms and fitness level. It should include significant load reduction compared to the training intensity that led up to the injury and must allow for adequate time for recovery. Running should be performed close to pain free, as bone stress injuries tend to not respond well to exercising with pain.
Our calf muscles have a protective effect in that they reduce the posteromedial bending stresses acting on the tibia during running (11-14), which has been confirmed by in vivo experiments (14). For that reason, it is important to avoid running with fatigued legs to reduce medial tibial stress, and the graded running program should therefore be performed before other leg exercises.
Resistance training is well known for its stimulating effect on BMD and bone CSA (6). It also appears that there is a direct correlation between calf muscle CSA and tibial bone CSA (6,15,16). Resistance training of the legs and calf muscles are therefore recommended as part of the rehab for MTSS. In order to achieve the desired effect on muscle and bone CSA, the load has to be high enough to stimulate bone and muscle growth.
Improving risk factors associated with MTSS
Risk factors associated with MTSS have two things in common:
They increase (directly or indirectly) compressive, bending or shear stresses at the posteromedial border of the tibia (type of activity, training load, foot biomechanics, weight and BMI, muscular fatigue, etc.).
Reduce tibia's ability to tolerate stress (nutritional status, hormonal dysfunction, bone geometry and BMD, inadequate rest).
Firstly, addressing these risk factors are also important in the prevention of MTSS in athletes. Secondly, improving on known risk factors may help aid rehabilitation and prevent recurrence of symptoms.
Bone health is closely linked to diet, including vitamin D and calcium status (17). Individuals with MTSS should ensure adequate nutrient intake through diet or dietary supplements. However, increasing intake beyond recommended values is not likely to give an added benefit. Recommended values for calcium and vitamin D is 1000 mg/day and 10 µg/day, respectively.
Women have a higher risk of developing bone stress injuries than men, including MTSS and stress fractures (3,18-21). This can in part be explained by what is known as the female athlete triad, which refers to the negative impact of long-term calorie deficit on estrogen levels and bone mineral density in physically active females.
Some seem to think that it is normal for female athletes to lose their menstrual periods due to strenuous activity, but this is a myth. Loss of menstrual periods (amenorrhea) is a medical condition with detrimental effects on bone health, commonly caused by sustained calorie deficits (with or without restrictive eating).
Greater degrees of foot pronation and navicular drop are well-known risk factors for MTSS as has been confirmed by several systematic reviews (3,22). Custom-made insoles are often recommended by therapists for as part of the treatment for MTSS; however, no studies have investigated its effectiveness in treating MTSS (1).
Several studies have investigated the use of various types of insoles for preventing MTSS in military recruits. Two studies found that shock-absorbing insoles reduced the risk of developing MTSS (18), while two studies found no effect of using custom-made insoles, heel insoles or foam insoles compared to standard insoles (18).
These results cannot easily be generalized to runners, since the biomechanics of running is different from marching, walking and running with heavy backpacks. The effect of insoles on treating MTSS is uncertain, but it cannot be excluded as a possibly beneficial complementary treatment option.
Listen to the podcast "Footwear advice for running injuries" with physical therapists David Pope and Tom Goom to learn more about the role of footwear in treating running injuries.
Extracorporeal shock wave therapy
Extracorporeal shock wave therapy (ESWT) is a treatment modality that is most commonly used in treating tendon pathologies; however, it has also been proposed as a treatment for MTSS. A systematic review from 2017 concluded that there is no evidence for the effectiveness of ESWT in patients with MTSS (23).
The only blinded randomized controlled trial that has been performed found no effect of 5 sessions with standard dose ESWT (total cumulative dose = 1450 mj/mm2) compared to sham-ESWT (70mj/mm2) in patients with MTSS. Interestingly, patients with sham-ESWT had less pain upon pressure than the experimental group after 10 weeks.