Introduction
The recent tragic death of Ryan Cox has highlighted the problem of vascular disease in the legs of cyclists. Vascular disease is extremely uncommon in the young and is usually associated with those who smoke, have diabetes or high cholesterol. For reasons that will be explained, racing cyclists appear at increased risk of developing arterial problems in the legs compared with healthy individuals. The exact numbers of athletes with this condition remain unknown but may be more common than currently appreciated. In one recent study, as many as one in five top-level cyclists show some evidence of flow limitations in the artery supplying blood to the leg. Other endurance athletes may be affected by the same problem including triathletes and cross-country skiers.

The problem
The artery affected is in the region of the groin just above the skin crease (external iliac artery). The artery becomes thickened and narrows, limiting blood flow to the leg. The problem is different to the narrowing of arteries due to smoking, cholesterol or diabetes.
In cyclists the artery may be damaged by repeated flexion and trauma as it goes around the hip joint. The large psoas muscles, which flex the hip, are particularly well developed in cyclists and aggravate the problem. Alternative theories include kinking of the artery because it is abnormally tethered in position or damage due to the abnormally high blood flow rates in the artery (Figure 1, figure 2.).

Symptoms
Patients with severe disease of the arteries usually complain of a cramp like pain in the calf, thigh or buttock when they walk. This is because the muscles are starved of oxygen. Cyclists who develop iliac artery problems rarely have such severe narrowing of the artery. Instead they typically complain of a weakness or lack of power in one leg after many miles of training or racing. As a result, the symptoms may be mistaken for muscular problems or ‘sacroiliac joint dysfunction.’

Diagnosis
Doctors and physiotherapists may not suspect arterial problems in a young, healthy athlete, making the diagnosis difficult. Clues to the problem may be gained from the symptoms but physical examination is usually entirely normal.
Diagnosis requires a centre with physicians with knowledge of vascular disease and access to specialist investigation tools to measure blood flow and pressure in arteries. These include ultrasound (Doppler) and MRI scanning.
The symptoms only come on during heavy workouts so it is often necessary to measure the blood pressure in the arteries during maximal cycle ergometer tests.

Treatment
A change of position on the bike to decrease hip flexion is known to be effective treatment for many cyclists with this condition. Non-professional cyclists may be better advised to take up other sports where hip flexion is less. A better alternative for the avid cyclist may be the recumbent.
Surgery should only be reserved for those cyclists who do not respond to other measures. All surgical procedures carry significant risk even when undertaken by experienced vascular surgeons. There are many potential complications both in the short and long-term. Surgery should not be performed without a full discussion of the potential risks involved. A variety of surgical procedures exist to treat diseased arteries. Minimally invasive (endovascular) treatments such as balloon dilatation (angioplasty) or stenting of the narrowed artery appear attractive because they are associated with fast recovery times. These minimally invasive techniques are not suitable for cyclists with iliac artery problems because of the high incidence of failure due to restenosis and complications such as stent fracture.
Surgical repair consists of release of the tethered external iliac artery, shortening it if necessary, and widening it with a patch of vein taken from the leg or arm (Figure 3.) Patches or grafts made of prosthetic material (eg polyester or PTFE) should be avoided because of the risk of infection and bleeding.

Conclusion
Iliac artery problems in racing cyclists require expert diagnosis and treatment. For many cyclists a modification of the position on the cycle may be sufficient to treat the problem. The few cyclists who need surgery should be assessed and treated by experts following a detailed discussion of the risks involved. When treated appropriately, most elite-level cyclists can expect to return to their previous level of performance.

Legends

Figure 1. Abnormal tethering of the external iliac artery by an excess of branches of the artery to the psoas muscle



Figure 2. After surgical release of the external iliac artery there is kinking



Figure 3. The external iliac artery has been shortened surgically and widened with a patch of vein taken from the leg.