By David K, Lisle, M.D.
Many Vermonters are getting outdoors to begin their training for the upcoming running season. With the increase in running there is often an increase in what is generically called chronic lower leg pain.
This pain is typically in the shin or the calf and the diagnosis can be difficult to make given that there are often ambiguous symptoms in multiple locations of the leg.
The broad array of causes includes three broad areas:
1) involvement of the bone — medial tibial stress syndrome (MTSS) also called shin splints, and stress fractures;
2) vascular system (popliteal artery entrapment syndrome),
3) 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 above diagnoses fall into a larger generic diagnosis called exercise related lower leg pain or ERLP.
Much has been written on ERLP and the literature differs on which one is more common. Some suggest that CECS and stress fractures occur more frequently and another suggests that MTSS is most common followed by CECS and stress fractures. In my experience, the prevalence largely favors shin splints, followed by stress fractures and then CECS.
When seeing patients with ERLP, I consider most often “the big three”: shin splints, stress fractures (tibia or fibula) and CECS. Determining which of the three diagnoses is correct relies on a thorough history and physical examination. Key questions include the specifics of training regimen, surface conditions and shoe wear. Running volume is also important, including knowing how far, how fast and how many days a week the patient runs.
Other important 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 of the “big three” as discussed below.
- Medial tibial stress syndrome (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. The use of Xrays is typically normal, and 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 two-three 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.
- Stress fractures to the tibia or fibula occur due to repetitive micro-trauma to bone that outsteps the body’s ability to heal itself. The tibia is most frequently involved in runners, however I have seen several distal fibular stress fractures. Stress fractures most often occur in women and the highest risk for a stress fracture occurs in those with a history of a prior stress fracture. The most important question to ascertain is the volume of training that led to the pain.
It’s also important to note that women with menstrual changes or eating disorders have a higher risk of stress fractures. Although beyond the scope of this article, there is an entity called ”the female athlete triad” that involves disordered eating that leads to lack of menstrual cycles that then leads to osteoporosis and stress injures to bone.
Athletes with suspected stress fractures will often report pain occurring with less and less activity. Classically this is someone who has leg pain that 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 and 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.
Xrays 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 currently 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.
- Lastly, 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. This is called “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.
To treat CECS, a pre-exercise physical examination is normal. Sometimes the calves will feel tight even at rest. Xrays are normally done. 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.
When determining what course of treatment is needed to treat MTSS, stress fractures and CECS, it is important to understand what differentiates each of the three to determine accurate diagnosis. With an accurate diagnosis, however, the athlete will be able to return to the sport faster and hopefully with a lower risk of injury down the road.