MEDIAL TIBIAL STRESS SYNDROME (MTSS) IN RUNNERS: MECHANISM OF INJURY, DIAGNOSIS, AND MANAGEMENT STRATEGY

Medial Tibial Stress Syndrome (MTSS), commonly referred to as “shin splints,” is an exercise-induced pain along the posteromedial border of the tibia.

PATHOPHYSIOLOGY AND CURRENT LITERATURE

The underlying pathology in medial tibial stress syndrome (MTSS) is bone overload. There are many different theories that purport to explain MTSS, but the bone overload theory is strongly supported by recent evidence. 

THE MECHANISM OF BONE STRESS INJURY AND BONE HEALING

We must understand the mechanism of bone stress injury and bone healing to manage and treat medial tibial bone syndrome (MTSS).

Bone remodels itself when there is damage to the bone. Remodeling is the sequential activity of bone-dissolving osteoclasts that remove the damaged bone, followed by osteoblasts that lay down bone-forming cells at the site of damage, fill the void, and form the base for new bone.

Bone stress injury indicates that the load-induced accumulation of micro-damage has outpaced the remodeling process of the bone. In the case of bone stress injury, a more porotic region appears at the site where the damage has outpaced the remodeling. In contrast to osteoporosis, where there is a general bone porosity, in bone stress injury, a specific region of the bone becomes porous because of the accumulated micro-damage and abruption in remodeling because of constant loading on that region of the bone. It makes the bone weak and reduces its ability to withstand the forces and loads imposed on it, which can lead to the stress fracture (1).
 Reproduced from Warden et al., 2021.

DIAGNOSIS OF MTSS

An accurate and reliable diagnosis can help clinicians makes a good foundation to discuss the patient’s expectations and develop an effective treatment plan.

• A good subjective history is essential to make an accurate diagnosis
• Differential diagnoses for medial tibial stress syndrome (MTSS) include: chronic exertional compartment syndrome (CECS), calf complex injuries, vascular pathologies, and nerve entrapments. We should consider all of these and make appropriate referrals if necessary.
• Spikes in training loads. Subjective history can inform us about any increase in the training loads in the past couple of weeks or even months because remodeling takes time, and spikes in loads may be long before the symptoms of MTSS appear.
• And mostly, the presenting complaint will be exercise-induced pain along the posteromedial border of the tibia. 

YATES’S CRITERIA FOR DIAGNOSING MTSS (2)

Yates’s criteria for diagnosing MTSS are given below:

• Exercise-induced pain along the posteromedial border of the tibia
• Pain on palpation on the posteromedial border of the tibia
• The site of pain spreading over a minimum of 5cm

Reproduced from east vic park physiotherapy

*We recommend rotating your phone to watch the videos*

BE AWARE OF THE MEDIAL TIBIAL STRESS FRACTURE.

We as clinicians must consider every possibility while examining a patient presenting with medial tibial pain. One of the most important differential diagnoses is the medial tibial stress fracture.

So how do we rule out medial tibial stress fracture?

A study by Charles Milgrom and colleagues in 2021 presented the guidelines for diagnosing the medial tibial stress fracture (3). The tibial stress fracture is more likely with the following presentation:

• The Pain on palpation is more localized. Or there is a focal point of tenderness on the anterior aspect of the tibia.
• A positive hop test

*We recommend rotating your phone to watch the videos*

Self-reported pain scores are not predictive of the medial tibial stress fracture. MRI is the most sensitive and specific and is the gold standard for diagnosing medial tibial stress fracture (4).

FREDERICSON CLASSIFICATION SYSTEM FOR MTSS

Fredericson et al, classified medial tibial stress syndrome based on the MRI findings (5). This classification system is used to estimate the delay in return to impact activity after MTSS. The grades of classification are depicted in the image, and the expected return to impact activity is given below based on these grades:
 Reproduced from Radiopedia.org

ESTIMATED RETURN TO IMPACT ACTIVITY BASED ON THE FREDERICSON CLASSIFICATION SYSTEM (6)

• Grade 1: 2-3 weeks
• Grade 2-4a: 6-7 weeks
• Grade 4b: 9-10 weeks or more

TREATMENT FOR MTSS

Warden et al, in 2021, put forward the key principles for medial tibial stress syndrome (MTSS) management, which include the following (7):

• Manage the load

• Maintain athlete’s fitness

• Address muscle function and find out where are the significant deficits in the strength

• Recommence and progress back to running gradually

• Reduce the risk of a subsequent injury

MANAGE LOADS

When it comes to loading a bone with stress injury, a clinician should look for pain-free loading. In the case of bone stress injury, the remodeling process is already outpaced by the damage, and any extra load will add up to that damage, further hindering the healing and remodeling process and leading to the weakening of the bone and the potential for stress fractures. So pain-free loading is essential in individuals with a bone stress injury.

MAINTAIN ATHLETE’S FITNESS

Cross training

• Athletes with medial tibial stress syndrome need to stay offload for a while and should not engage in impact activities. This offloading and restraint from impact activities can potentially affect their fitness. So we need to encourage the athletes to do the things they can and engage in multiple low-impact activities to maintain their fitness. The athletes are encouraged to engage in swimming, bicycling, and deep-water running. These activities benefit a lot in maintaining the cardiovascular and aerobic fitness of the athlete without putting high loads through the bone.

Energy availability

• We should consider the energy availability in the athletes presenting with bone stress injuries (BSI) because athletes with BSI usually show signs of relative energy deficiency and low BMI to fuel their training. We should also consider the sleeping habits of the athlete because these can affect their performance, predisposing them to injury. We should consult a dietician or nutritionist and not involve the athlete in cross-training that exceeds the energy availability.

ADDRESS MUSCLE FUNCTION

The key muscles to address in athletes with medial tibial stress syndrome (MTSS) are calf complex muscles, glute, and quadriceps. The calf complex includes gastrocnemius and soleus. The deficit in the calf complex can increase stress on the tibia leading to more disruption in the healing process.

The other key muscles to address in individuals with MTSS include the glutes, hip abductors, and quadriceps muscles. These muscles stabilize the hip and take most of the body weight. If there is a strength deficit in these muscle groups, increased body weight can be transferred through the tibia, causing stress injuries. 

So if a patient comes with MTSS, we need to address these muscle groups and build strength if necessary to help reduce the stress through the tibia and allow the stress injury to heal.

RECOMMENCE AND PROGRESS RUNNING (7)

Before recommencing running consider the following:

• The individual should be pain-free in daily activities for 5-days
• The individual has demonstrated progressive loading and has enough tissue capacity and strength to withstand the loads put on it while the individual returns to the pre-injury activity level.
• There should be a phased return to running by starting with walking and progressing to running.
• Consider progressing the volume of training before increasing the intensity. Try to implement periodization principles for a phased return to training.

REDUCE THE RISK OF A SUBSEQUENT INJURY (7)

We as clinicians should focus on the bigger picture and look for ways to reduce the risk of a subsequent injury. We might consider the following for this purpose:

• Address potential training errors
• Look for any signs of relative energy deficiency
• Involve multidisciplinary team early if necessary
• Include gait retraining

REFERENCES

1. Warden SJ, Edwards WB, Willy RW. Preventing Bone Stress Injuries in Runners with Optimal Workload. Curr Osteoporos Rep. 2021;19(3):298-307.
2. Yates B, White S. The incidence and risk factors in the development of medial tibial stress syndrome among naval recruits. Am J Sports Med. 2004;32(3):772-80.
3. Milgrom C, Zloczower E, Fleischmann C, Spitzer E, Landau R, Bader T, et al. Medial tibial stress fracture diagnosis and treatment guidelines. J Sci Med Sport. 2021;24(6):526-30.
4. Pegrum J, Crisp T, Padhiar N. Diagnosis and management of bone stress injuries of the lower limb in athletes. Bmj. 2012;344:e2511.
5. Fredericson M, Bergman AG, Hoffman KL, Dillingham MS. Tibial stress reaction in runners. Correlation of clinical symptoms and scintigraphy with a new magnetic resonance imaging grading system. Am J Sports Med. 1995;23(4):472-81.
6. Kijowski R, Choi J, Shinki K, Del Rio AM, De Smet A. Validation of MRI classification system for tibial stress injuries. AJR Am J Roentgenol. 2012;198(4):878-84.
7. Warden SJ, Edwards WB, Willy RW. Optimal Load for Managing Low-Risk Tibial and Metatarsal Bone Stress Injuries in Runners: The Science Behind the Clinical Reasoning. Journal of Orthopaedic & Sports Physical Therapy. 2021;51(7):322-30.