Chronic Exertional Compartment Syndrome
Exercise Induced Leg Pain (EILP) is a condition of pain in athletes between the knee and the ankle, either in the muscle bulk of the calf or on the surface of the tibia.
Historic descriptions such as 'Shin Splints' are unhelpful and should not be used as it is an umbrella term used for a variety of different conditions affecting the leg. The term itself stems from a description from the AMA in 1968 "Pain and discomfort in the leg from repetitive running on hard surfaces or forcible extensive use of flexors… the diagnosis should be limited to musculo-tendinous inflammation excluding a stress fracture or ischaemic disorder"
There are many possible causes of EILP, which include:
Chronic Exertional Compartment Syndrome
Stress Fracture & Medial Tibial Stress Syndrome
Superficial Peroneal Nerve Entrapment
Popliteal Artery Entrapment
Radicular leg pain ('sciatica')
Chronic Exertional Compartment Syndrome (CECS):
Compartment Syndrome is defined by Matsen (1980) as "A condition in which increased pressure within a closed anatomical space compromises circulation and the function of the tissues within the space"
The calf is divided into various compartments by a fibrous structure called 'fascia' which is flexible, but cannot stretch (similar to canvas rather than rubber) If there is swelling in one of these compartments, most commonly the muscles at the front of the calf (anterior compartment) then the compartment cannot expand, and the pressure in the compartment rises.
The four compartments of the calf are the anterior and peroneal compartments at the front/ outer side, and the superficial and deep posterior compartments at the back of the calf.
The most common type is acute compartment syndrome, which is a surgical emergency whereby bleeding from a fracture causes a rise in pressure, which if unchecked can exceed capillary perfusion pressure such that muscle capillary flow ceases and leads to muscle death. There is commonly a deformity due to scarring of the dead muscle known as a Volkmann's Ischaemic Contracture.
In CECS however, the onset is more gradual. It is caused by an increased pressure during exercise, classically in the anterior compartment, and classically bilateral. It is often felt as a pain & ‘rock hard’ feeling in the muscle belly, and sufferers are unable to ‘run through it’. It often eases within a few minutes, such that people are often able to run a little further but recurs rapidly, and exercise tolerance gradually decreases.
Examination is mainly to rule out other causes;
Tenderness would suggest MTSS (can co-exist)
ANT test by SLR/ slump test
Peripheral neurovascular status
The diagnosis is therefore clinical, and confirmed by compartment pressure testing, which can be static or dynamic.
Static pressure testing is with a probe inserted into the anterior compartment before and after exercise, and a couple of minutes later.
Static Pressure Testing using a Stryker monitor
Dynamic testing however involves inserting multiple catheters and actually measuring the pressure during exercise, and the tail off after exercise. The absolute figures are debatable, but a significant rise or a delay in return to baseline after exercise are strongly suggestive of CECS.
Dynamic Pressure Testing with transducers linked to computer
Unfortunately conservative treatment for CECS is commonly ineffective, though stretching with a good sports physio, deep massage and attention to gait may help. Orthotics are rarely effective and may even exacerbate the situation.
Surgery can provide relief in over 80% of cases with classic symptoms, but there are those who even with pressure raise on testing and classic symptoms do not improve for reasons which are not clear.
The surgery involves release of the full length of the fascia over the involved compartment (or compartments) from knee to ankle. This can be done via two small skin incisions, but this means there may be bleeding and bruising postoperatively.
The operation is performed as a day case, usually under general anaesthetic, and takes about 30 minutes. stretching exercises start immediately post op and need to be kept up for several weeks, stitches are removed about 10 days post op. There may be bruising of the local nerves causing numb patches, particularly of the superficial peroneal nerve that may cause scarring and nerve entrapment leading to a numb patch on outer ankle and on to the top of the foot. The risks of other complications such as wound infection is about 1% per wound, but if both sides are done there are 4 wounds.