What happens in the shin
The tibialis posterior, soleus, and flexor digitorum longus muscles are attached to the inner edge of the tibia. With each step, they absorb shock and support the arch of the foot by pulling on the periosteum. If the load increases faster than the tissues have time to adapt, irritation develops in the attachment zone, and the bone begins to rebuild: areas of resorption outpace the formation of new bone tissue. That is why periostitis and stress fracture are considered links in the same chain. The difference is that with periostitis the pain is spread along the length of the bone, and with a stress fracture it is a point pain.
- Overload of the area of attachment of the lower leg muscles
- Restructuring of bone tissue under repeated shock loads
- Diffuse pain over several centimeters of bone
- Continued stress leads to stress fracture
- The inner edge of the lower and middle third of the leg is most often affected
Causes and risk factors
The main reason is that the impact load increases too quickly: doubling the mileage, returning to training after a break, switching to asphalt or running uphill, intensive preparation for competitions. Features of the foot, weakness of the lower leg and pelvic muscles, and worn-out shoes contribute. In girls and women, especially with cycle disorders and nutritional deficiencies, the risk is higher due to decreased bone density. Vitamin D deficiency and low calcium intake also impair bone strength.
- Sudden increase in training volume or intensity
- Hard surface and uphill running
- Worn or ill-fitting sneakers
- Flat feet, overpronation, cavus foot
- Weakness of the muscles of the lower leg, foot and pelvis
- Vitamin D and calcium deficiency, nutritional and cycle disorders
Symptoms and how to differentiate from a stress fracture
Periostitis begins as a dull, aching pain along the inner edge of the shin, which appears at the beginning of a run, subsides during the warm-up and returns after training. When pressed, an extended area is painful - several centimeters or more. A stress fracture behaves differently: the pain is pinpoint, intensifies with each workout, does not go away when warming up, and bothers you when walking and at night. Jumping on one leg with a stress fracture is extremely painful. It is important to distinguish between these conditions, because the tactics and timing of unloading are different.
- Aching pain along the inner edge of the tibia
- Pain in an extended area on palpation
- Pain at the beginning of a run, decreasing as you warm up
- Sometimes slight swelling and hardening along the edge of the bone
- Point pain and pain at rest are a reason to suspect a stress fracture
- Complaints often come from both sides
Diagnostics
The diagnosis is mainly clinical: the doctor evaluates the nature of the pain, the length of the painful area, the foot, shoes and training plan. X-rays of the lower leg in the first weeks are usually normal and are needed to rule out other causes; signs of bone restructuring appear late. If there is a suspicion of a stress fracture, the most informative MRI is that it shows bone marrow edema long before changes on the x-ray. Ultrasound helps evaluate soft tissue and tendons. For repeated episodes, vitamin D, calcium and, in women, menstrual status are checked.
- Inspection with palpation along the length of the bone and jump test
- X-ray of the lower leg bones in two projections
- MRI of the leg for suspected stress fracture
- Ultrasound of the soft tissues of the leg
- Tests for vitamin D and calcium during relapses
- Foot assessment and shoe selection
Treatment and return to exercise
The main treatment is to temporarily reduce the impact load to a pain-free level, usually for 2 to 6 weeks. Complete bed rest is not needed: swimming, aqua jogging, cycling and strength exercises are maintained without impact. Ice after exercise, working on running technique with shortening the stride and increasing the frequency of steps, strengthening the calf muscles, muscles of the foot and pelvis help. For flat feet, insoles are selected and worn-out shoes are changed. Physiotherapy and shock wave therapy are used as adjuncts. Painkillers are prescribed by a doctor; You cannot mask the pain with medications and continue training.
- Impact reduction for 2–6 weeks
- Swimming, water running and cycling during the fasting period
- Ice on the painful area after exercise
- Strengthening the calf, foot and pelvic muscles
- Correction of running technique and selection of shoes, insoles if necessary
- Gradual return to running based on the pain-free principle