With the temperate autumn days here, Vermonters may be enjoying their running training. Some of us, however, may experience a series of diagnoses generically called “chronic lower leg pain.” These problems can occur with any amount of overuse through impact exercise and often can be seen in young athletes when they return to running in the fall.
What is chronic lower leg pain?
Chronic lower leg pain is typically pain in the shin or the calf and the actual diagnosis can be difficult to make given that there are often ambiguous symptoms with pain in multiple locations of the leg. The broad array of causes includes involvement of the bone (medial tibial stress syndrome (MTSS), also called shin splints and stress fractures), vascular system (popliteal artery entrapment syndrome), muscles and tendons (chronic exertional compartment syndrome (CECS)), calf strains and tendinitis, or referred pain from nerve entrapments. Referred pain into the lower leg can also be from the knee or even from the hip in young athletes. These diagnoses fall into a larger generic diagnosis called “exercise related lower leg pain” or ERLP.
How we treat leg pain
When seeing patients with ERLP, I consider most often “the big three”: MTSS (or shin splints), stress fractures (tibia or fibula) and CECS. Determining which of the three diagnoses is correct relies heavily on a thorough history and physical examination. Key questions include involve the specifics of training regimen, surface conditions and shoe wear. Also, I need answers to something I refer to as running volume – which is how far, how fast, and how many days a week a patient runs. Other questions include:
- How quickly does the pain begin?
- Does the pain continue to get worse or does it plateau?
- Upon cessation of running, how quickly does the pain improve?
- Does the pain continue into the next day?
- Does pain seem to occur with less and less activity?
- Have there been any changes in training intensity or a change in shoe type?
All of these questions help clarify the diagnosis.
Diagnosis: Medial Tibial Stress Syndrome (MTSS)
MTSS is most often seen in distance runners, but can also occur in those involved with court sports (tennis, basketball, and volleyball). MTSS is tender to press on and often will begin very soon after starting activity. Although the pain can be a severe, dull ache, often athletes can push through the pain as it can plateau and sometimes even diminish with continued activity. With rest, the pain is alleviated and most often pain is not felt at night. In the later stages of MTSS, however, severe cases can cause pain at night and at rest.
On examination, there is tenderness in the shins localizing most often to the lowest part of the inside of the leg. This is called the distal posteromedial aspect of the tibia. X-rays are typically normal but are often important to evaluate for presence of stress fractures or other rare pathologies. Once the diagnosis is made the treatment involves a period of rest for 2 -3 weeks with cross-training in lower impact activities (biking, swimming, or elliptical trainer). Biomechanical issues need to be addressed, such as foot pronation and running mechanics. Physical therapy can be very helpful for this. Gradual return to activity over a 3 – 6 week period is advised.
Diagnosis: Stress Fracture
Stress fractures to the tibia or fibula occur to due repetitive microtrauma to bone that outsteps the body’s ability to heal itself. The tibia is most frequently impacted by running, however, I have seen several distal fibular stress fractures.
Stress fractures most often occur in women and the highest risk for a stress fracture occur in those with a history of a prior stress fracture. Specific historical questions that need to be answered include clarification of training volume. Women with menstrual changes or eating disorders have a higher risk of stress fractures.
Athletes with suspected stress fractures will often report pain occurring with less and less activity. Classically, this is someone who has leg pain who started at mile 5 on one day, then the next day it is at mile 3, then mile 1 and then with walking around the house.
Stress fractures are often tender to touch well localized to the area of injury. Initially, the pain will subside after exercise but as a stress fracture progresses, the pain will continue after cessation. There is sometimes swelling to the area as most often the leg will appear normal. X-rays of the tibia and fibula will appear normal in the early stages however later the films may show the body’s attempt to heal the stress fracture. When the diagnosis is not clear, magnetic resonance imaging (MRI) is the study of choice to differentiate stress fractures from MTSS. The hallmark for treatment of any stress injury involves maintaining a pain free level of activity. This can vary greatly in duration. When everyday activities are pain-free, a gradual return to exercise can begin with special attention to any training errors that may have caused the injury.
Diagnosis: Chronic Exertional Compartment Syndrome (CECS)
Chronic exertional compartment syndrome involves pain in the lower leg from muscle tissue that does not have enough room in a rigid envelope that surrounds the muscle. Many theories exist as to why this occurs. CECS typically involves aching, cramping, or tightness in the leg involving the calf or outer leg muscles, which occurs after a specific amount of exercise. It typically does not begin right away. Once the pain begins, it will increase to the point where it is often very difficult to continue exercise. I call this crescendo pain. When the athlete finally does stop exercise, their pain will soon resolve completely until exercise is attempted again.
The athlete will report firm muscles and often will see small bumps around the muscle that are due to muscle hernias pushing through the fascia due to high pressure in the muscle compartment. In some CECS, athletes will experience numbness and tingling to the top of their foot and often heaviness to their feet with a “foot slap” that occurs while running.
Pre-exercise physical examination is typically normal. Sometimes the calves will feel tight even at rest. X-rays will be normal. The diagnostic test of choice is compartment pressure testing that involves a special digital pressure gauge. The pressures are measured in the compartments prior to exercise and then immediately after exercise when symptoms are present. A period of rest, activity modification and identifying any biomechanical issues is necessary, but often this does not fully resolve the symptoms. Often, operative fasciotomy is necessary to treat CECS.
Conclusion: The Important of a Correct Diagnosis
Exercise-related leg pain most often involves the big three: MTSS, stress fractures, and CECS. Understanding what differentiates is critical to an accurate diagnosis and is largely dependent on answers to specific questions surrounding the athlete’s pain. Sometimes further testing of x-rays, MRIs, or compartment pressure testing is necessary. Only with an accurate diagnosis can the correct treatment plan begin to allow the athlete to return to sport faster and hopefully with a lower risk of injury.
David K. Lisle, MD, CAQSM, is a sports medicine physician at the University of Vermont Medical Center’s Orthopedic and Rehabilitation Center. He is also an assistant professor in the Department of Orthopaedics and Rehabilitation and the Department of Family Medicine.