Overview of peripheral vascular problems in athletes

INTRODUCTION — Vascular pathology related to athletic activities comprises a spectrum of disorders that are uncommon, but when they do occur, they may threaten the athletic career [1,2]. Vascular injury is often due to high-stress, repetitive activity that results in trauma to vascular structures (veins or arteries), but other mechanisms can be involved. While the resultant damage (stenosis, compression, embolism) and symptoms are similar to vascular pathology caused by other etiologies (eg, atherosclerosis, degenerative disease), the presenting patient is usually much younger with few or no typical cardiovascular risk factors. Additionally, the urgency of the presentation is often more acute.

An overview of risk factors, symptoms, and management of athletic-related vascular problems is reviewed.

RISK FACTORS AND MECHANISMS — Vascular injury is often secondary to repetitive motions that can occur with many athletic activities, but other mechanisms of vascular insufficiency can occur. Typical risk factors for arterial (eg, smoking, hypertension, hyperlipidemia) or venous disease (prolonged standing, varicose veins) are often not associated with these disease processes. Generally speaking, athletes are young and healthy and present with extremity or other symptoms that are induced by the vigorous training postures or repetitive high-intensity motions associated with their sport.

Repetitive extremity movements

●Upper extremity – Upper extremity vascular disorders are seen in athletes performing repetitive arm motions (eg, throwing/pitching motion) that compress or induce repetitive trauma to the affected artery or vein. This may result in vascular thrombosis, aneurysmal degeneration, or embolism resulting in ischemia [3]. Certain athletes are thought to have a higher predisposition for these vascular disorders due to repetitive overhead motions, leading to hypertrophy of the scalene and pectoralis muscles within the scalene triangle in conjunction with the development of shoulder girdle instability. Sports particularly affected include baseball, softball, swimming, water polo, rowing, volleyball, and American football [4]. Anatomic anomalies (eg, cervical rib) may be seen in a minority of cases [5]. (See 'Anatomic anomalies' below.)

●Lower extremity – Recurrent exertional activity or positioning in athletes can also lead to lower extremity vascular pathology, particularly in competitive runners (any distance), skiers (downhill, cross country), basketball players, American football players, martial artists or bicyclists [6]. Repeated vascular compression in some pathologies (eg, popliteal entrapment, adductor canal syndrome, chronic exertional compartment syndrome) is secondary to hypertrophy or volume expansion of muscles. In others (eg, external iliac compression), assuming certain postures repetitively may lead to mechanical stress on the vasculature.

Muscular hypertrophy — In both the upper and lower extremities, muscle hypertrophy or muscle volume expansion during physical training may also predispose athletes to position-dependent vascular compression (artery or vein). (See 'Repetitive extremity movements' above.)

Anatomic anomalies — Anatomic anomalies (eg, musculoskeletal aberrations, aberrant arterial or venous anatomy) may lead to vascular problems during athletic activity. These anomalies may or may not be known prior to the onset of the athletic activity.

VASCULAR SYMPTOMS — The clinical presentation of vascular disorders in athletes varies and may include a wide spectrum of symptoms related to arterial or venous pathology including extremity pain, weakness, early limb fatigue, cramping, paresthesias, extremity swelling during strenuous exercise, and skin discoloration or other skin changes [7]. A vascular etiology is often overlooked in athletes with extremity symptoms, with symptoms often initially attributed to musculoskeletal injury, delaying the diagnosis. Thus, it is important to maintain suspicion.

Acute limb ischemia — Acute limb ischemia occurs secondary to sudden arterial occlusion (eg, embolism, thrombosis), or rarely, from extensive venous occlusion (ie, phlegmasia).

In young athletic individuals, embolism is generally related to proximal arterial pathology, and rarely, cardiac issues. Obstruction and thrombosis may occur in some athletic-related vascular conditions due to the compressive effects of muscles/bones that constrict the vessels. Vessels may also be damaged due to repetitive activity, with a resultant intimal injury resulting in a thrombotic surface that subsequently thromboses. (See 'Repetitive extremity movements' above.)

The symptoms of acute limb ischemia in an activity-related vascular injury are the same as those from other causes and usually consist of sensory changes (numbness/tingling) progressing to muscle weakness/paralysis, depending upon the extent and duration of blockage. Patients will typically have elements of the "six P's" of acute limb ischemia in the affected limb, including pain, pallor, poikilothermia, pulselessness, paresthesia, and paralysis, with symptoms usually presenting distally in the limb and progressing proximally with the extent of occlusion and length of time affected. The acuity of acute limb ischemia can be classified according to the Rutherford classification of acute limb ischemia (table 1), which also directs the urgency of repair. (See "Overview of upper extremity ischemia", section on 'Acute ischemia' and "Clinical features and diagnosis of acute lower extremity ischemia".)

Exertional limb pain — Any process that reduces blood flow to the extremity has the potential to produce ischemic limb pain with exertion. In older adults, the most common cause and familiar to clinicians is atherosclerosis; however, in younger patients, and especially in athletic individuals, this is rarely a cause.

●Claudication – In athletes, claudication occurs during activity or with positioning of the extremity that repeatedly compresses the artery by nearby musculotendinous structures (eg, entrapment syndromes, adventitial cystic disease, adductor canal syndrome, external iliac endofibrosis) [2,8]. The location of claudication depends on the activity-related location of the pathology.

●Upper extremity pain – Upper extremity pain in athletes is also most pronounced when the patient is assuming a position or movement that induces compression of the vascular structure (eg, throwing motion), which can vary. During these positions, the patient may report pain, early fatigue, paresthesias, or swelling [3].

Limb swelling — Athletes may exhibit limb swelling with vigorous activity due to venous outflow obstruction. The degree of limb swelling and other symptoms and signs related to venous obstruction, such as extremity pain or collateral venous patterning, are related to the extent and severity of obstruction and its time course. Acute obstruction such as occurs with venous thoracic outlet syndrome can lead to sudden, severe extremity swelling. Intermittent, partial obstruction is associated with dull aching pain, engorged upper extremity superficial veins, and dependent swelling. (See "Clinical features, diagnosis, and classification of thoracic central venous obstruction", section on 'Symptoms and signs' and "Overview of iliocaval venous obstruction", section on 'Clinical features' and "Clinical presentation and diagnosis of the nonpregnant adult with suspected deep vein thrombosis of the lower extremity", section on 'Clinical presentation'.)

VASCULAR EVALUATION — Early recognition of a vascular problem is important in high-functioning athletes to avoid the consequences that may delay a return to competition. Many athletes will present with symptoms that have existed for months or even years, and these patients can be evaluated on an elective basis. However, if an athlete has an acute change in symptoms (especially if within a few days), a more urgent workup is warranted to rule out the possibility of acute limb ischemia or acute venous thrombosis.

Once an underlying vascular etiology for an athlete's symptoms is suspected based upon the history and physical exam, a variety of diagnostic tests can help to confirm or reject the hypothesis. Differentiating between musculoskeletal injury and vascular pathology clinically relies on performance of a vascular physical examination with provocative maneuvers. Obliteration of a pulse or onset of limb fatigue during provocative maneuvers should raise clinical suspicion for one of the arterial etiologies discussed below. Unilateral swelling, tenderness, and blue/purple discoloration may point more towards a venous pathology. (See 'Specific disorders' below.)

Initial screening of suspected arterial pathology — For patients presenting with ischemic symptoms, noninvasive vascular studies such as the ankle-brachial index (ABI) or wrist-brachial index (WBI) should be performed in the lower or upper extremities, respectively. The ABI is a ratio of the blood pressure in the arm to the blood pressure in an ankle artery (either the dorsalis pedis artery or the posterior tibial artery). A normal ABI is greater than 0.9 and has a triphasic waveform. Similarly, the WBI compares pressure measurements obtained for the radial and ulnar arteries at the wrist and brachial arteries in each extremity. The normal WBI is 1. (See "Noninvasive diagnosis of upper and lower extremity arterial disease", section on 'Ankle-brachial index' and "Noninvasive diagnosis of upper and lower extremity arterial disease", section on 'Wrist-brachial index'.)

The benefits of these studies are that they are noninvasive, quick to perform, and inexpensive compared with most other types of vascular testing. They are therefore useful as a screening test to differentiate arterial pathology as a cause of exertional limb pain from other possible etiologies. The downside of these noninvasive studies is that although ABI or WBI can help confirm arterial obstruction as the cause of symptoms, it does not identify a specific location or the underlying etiology behind that problem. Thus, vascular imaging is generally required. (See 'Vascular imaging and evaluation of soft tissue' below.)

It is important to obtain exercise testing in athletes. At the standard lower levels of exertion used to test the typical claudicant with atherosclerosis, athletes often don't experience symptoms and exercise tests don't often become positive. Thus, it is important that exercise testing is performed at sufficient type of exertion and duration that provokes the described symptoms. As an example, cyclists can be tested before and after riding a training bicycle to the point of symptom onset.

Exercise ABIs will often unmask physiologically significant arterial physiology when the resting ABI is otherwise normal. As an example, external iliac artery endofibrosis (EIAE) can present with vague exertional symptoms that may or may not fit a classic description of claudication. However, exercise ABI has an 85 percent sensitivity in demonstrating physiologic arterial pathology in this patient population [9]. ABIs can similarly be useful in patients with popliteal artery entrapment syndrome [10].

Vascular imaging and evaluation of soft tissue — Dynamic vascular imaging, while frequently used in other clinical settings, is particularly important in the evaluation of the athlete. Ultrasound, axial imaging (computed tomographic [CT], magnetic resonance [MR]), and catheter-based angiography can all be done with the athlete performing the movements that trigger the symptoms. For some imaging modalities, these movements can be performed in real time. In the athlete, imaging of the soft tissues is also important to evaluate for structures (hypertrophied muscles, anomalous bands) that may be causing compression of an artery or vein.

Duplex ultrasound and dynamic imaging — Duplex ultrasound provides information on the diameter of the vessel (eg, aneurysm) as well as the flow through the vessel, which detects partial or complete thrombosis (arterial or venous) or an elevation in velocities that is suggestive of stenosis (arterial or venous). For evaluating athletes, one of the strengths of ultrasound is dynamic imaging, which entails obtaining real-time images and velocities during extremity movement (eg, moving the arm from neutral position to abduction for the evaluation of arterial thoracic outlet syndrome [TOS]). Dynamic ultrasound can be helpful in making the diagnosis in EIAE, popliteal entrapment syndrome (PES), and adductor canal syndrome. The main drawback to duplex ultrasound is that imaging quality is operator dependent. An inexperienced technician may miss subtle pathologic signs. Furthermore, dense musculature typical of athletes can oftentimes lead to a suboptimal evaluation and an erroneous conclusion of a normal vasculature.

Catheter-based angiography — Catheter-based angiography involves gaining arterial access to the vascular tree of interest with either a 4 or 5 Fr catheter and using iodinated contrast and digital subtraction angiography to better delineate the flow of blood through the arterial or venous system. Angiography can also be used to obtain dynamic images with the athlete performing the movements that trigger the symptoms. Making the diagnosis of arterial TOS is the classic example of dynamic imaging with angiography. An angiogram is first performed with the limb in a neutral position and then the affected arm is abducted and externally rotated and the images compared. Compared with a CT angiography, catheter-based angiography can often be accomplished with less contrast and significantly less radiation. The downside of angiography is that it is an invasive procedure and has inherent risks associated with vascular access (eg, hematoma, thrombosis, dissection). There are no series specifically studying the risk of extremity angiography in athletes, but complications are typically less than 1 percent [11]. One would expect the rate in otherwise healthy athletes to be even lower because of less atherosclerotic and calcific arterial disease.

CT and MT imaging — CT and MR imaging are being used more frequently for the evaluation of arterial and venous pathologies. The benefits of these technologies are that they are noninvasive and generally more readily available. Furthermore, they provide true cross-sectional imaging of the vasculature and its relationship to surrounding structures, which can help localize the vascular lesion and help determine what treatment would be best to address it. As an example, a CT scan obtained in neutral position versus plantar flexion may help to demonstrate PES. Compared with CT, MR provides a higher level of soft tissue detail, which can be helpful in demonstrating aberrant bands of the gastrocnemius is causing the popliteal compression. The main disadvantage of CT/MR imaging is the cost as well as the requirement to perform multiple scans (using more contrast agent) to obtain the required positional imaging.

DIFFERENTIAL DIAGNOSIS — Musculoskeletal injury is the most common cause of pain in athletes. Many of the symptoms related to musculoskeletal injury mimic those due to vascular pathology, which can lead to misdiagnosis. As an example, claudication may be mistaken for muscle sprain or strain. Various musculoskeletal injuries may also cause swelling or discoloration of extremities, so venous compression or thrombosis may not be initially considered. Given that symptoms overlap, it is important to maintain clinical suspicion for a vascular etiology in athletes presenting with sudden or exertional limb pain or limb swelling. (See "Approach to hip and groin pain in the athlete and active adult" and "Running injuries of the lower extremities: Risk factors and prevention".)

SPECIFIC DISORDERS

Upper extremity

Thoracic outlet syndromes — Thoracic outlet syndrome (TOS) refers to a constellation of signs and symptoms that arise from the compression of the upper extremity neurovascular bundle as it traverses the thoracic girdle. Compression of the different components of the neurovascular bundle in one of three distinct spaces (figure 1) results in varied clinical presentations. Athletes are at higher risk for developing TOS due to increased compression from musculature developed in training. Amongst athletes, TOS is most frequently seen in sports that require repetitive movements of the upper extremities with the arms above shoulder level [4,12-24]. (See 'Risk factors and mechanisms' above.)

●Neurogenic TOS – Neurogenic TOS (nTOS) is the most common TOS manifestation and occurs because of compression, irritation, and injury of the brachial plexus in the thoracic outlet. Although the exact incidence in athletes is unknown, nTOS occurs in 3 to 80 cases per 1000 in the general population, and is thought to be higher in athletes [25]. nTOS manifests as pain, paresthesia, and weakness associated with elevation or sustained use of the affected upper extremity. The diagnosis of nTOS is complex, as it is generally a diagnosis of exclusion [4]. Workup may consist of physical examination demonstrating symptoms with provocative maneuvers, electromyographic testing, CT or MR imaging, and scalene muscle test injection. nTOS is initially managed conservatively with weight loss and cessation of activity, however, cessation of sport is generally not an acceptable long-term treatment to high performance athletes. This is followed by four to six weeks of targeted physical therapy. If symptoms progress or become disabling after nonoperative therapy, surgical decompression of the thoracic outlet is considered. Initial success rates with surgery are approximately 90 percent, but response may be transient, as success rates decrease with time from 64 to 71 percent [26].

●Venous TOS – Venous TOS (vTOS) accounts for 3 to 5 percent of all TOS cases and occurs due to prolonged and recurrent compression of the axillary and subclavian veins resulting in endothelial injury, intimal fibrosis, and a prothrombogenic low-flow state. Additional compressive forces are generated in athletes with hypertrophy of the anterior scalene and subclavius muscles predisposing this subset to vTOS. Competitive athletes who perform repetitive overhead motions with the upper extremity, including baseball players, weightlifters, volleyball players, and swimmers, are at increased risk.

Patients with vTOS may present with acute thrombosis (spontaneous upper extremity deep vein thrombosis) of the axillary or subclavian vein or with chronic obstructive thrombosis [24]. (See "Overview of thoracic central venous obstruction".)

•Primary (spontaneous) upper extremity deep vein thrombosis – Primary (spontaneous) upper extremity deep vein thrombosis, also known as Paget-Schroetter syndrome (PSS), is defined as acute thrombosis of the axillosubclavian veins due to compression by the thoracic outlet. Athletes with PSS present with severe pain, discoloration, and swelling of the arm following strenuous upper extremity activity. The diagnosis may be confirmed with duplex ultrasound imaging. Treatment in athletes is generally aggressive, using a combination of initial anticoagulation followed by thrombolysis and thoracic outlet decompression. The timing for surgical decompression of the thoracic outlet varies amongst practitioners; however, most protocols recommend decompression during the same hospitalization or within two weeks of thrombolysis [24,27]. (See "Primary (spontaneous) upper extremity deep vein thrombosis".)

•Intermittent positional obstruction – Intermittent positional obstruction is defined as repetitive venous injury leading to inflammation and chronic thrombosis. Athletes may present with painful nonpitting edema of the affected upper extremity as well as dilated subcutaneous venous collateralization noted on the chest, shoulder, and back (ie, Urschel sign). Patients may also report bluish discoloration, heaviness, easy fatigability, and shoulder pain associated with exercise or activity. The diagnosis can be confirmed with duplex ultrasonography with provocative maneuvers to evaluate venous compression. Plain radiographs, CT or MR angiography, or catheter-based venography with provocative maneuvers are useful adjuncts to establish the diagnosis. Conservative management with anticoagulation is not recommended, as studies report progression of thrombotic venous disease, which may lead to permanent disability. As such, management requires surgical decompression via first rib resection with venous reconstruction, if needed [24].

●Arterial TOS – Arterial TOS (aTOS) occurs from compression of the subclavian or axillary artery and accounts for <1 percent of TOS. Although the incidence of aTOS in athletes in unknown, one study reported a drop in brachial artery blood pressure >20 mmHg in 56 percent of athletes with extremities in a throwing position, and a loss of detectable blood pressure in 13 percent of extremities indicating intermittent compression during these motions [14]. Repetitive trauma to the artery results in endothelial injury, thrombus formation, and aneurysmal degeneration. Patients may present with symptoms of ischemia, including pain, discoloration, paresthesia, and decreased motor function as a result of arterial thromboembolization. The diagnosis of aTOS can be confirmed with duplex ultrasound or CT/MR imaging. Management involves addressing the acute ischemia with anticoagulation and thrombolysis or surgical thrombectomy followed by thoracic outlet decompression with arterial repair. The extent of arterial pathology determines whether primary repair, interposition with a conduit, or distal bypass is warranted [13].

Several options are available for thoracic outlet exposure and decompression. The approach chosen depends on the etiology and location of the compression, the need for vascular reconstruction, and surgeon and patient preferences. (See "Overview of thoracic outlet syndromes", section on 'Indications for surgery'.)

Upper extremity aneurysmal disease — Several circumstances can lead to aneurysm formation in the athlete.

●Poststenotic aneurysm – When local trauma or direct compression causes an arterial stenosis, as seen in aTOS, poststenotic dilation can develop, which can eventually progress to aneurysmal degeneration [6]. The exact mechanism is not known but may be related to the increased velocity and turbulence of flow in the stenotic area. When it occurs in the setting of extrinsic compression, such as with aTOS, the arterial space must first be decompressed with excision of the rib or removal of fibrous bands or anomalous anatomy. This is followed by repair of the artery, which can be repaired directly, bypassed, or managed using endovascular techniques.

●Repetitive injury – Another common cause of aneurysmal degeneration in athletes is direct repeated trauma to the vessel itself, as is seen with hypothenar hammer syndrome (see 'Hypothenar hammer syndrome' below)

Certain peripheral aneurysms are prone to sudden thrombosis causing acute limb ischemia, or distal embolism phenomenon causing digit ischemia. Aneurysmal disease can also cause a mass effect on adjacent nerves. Peripheral aneurysms are somewhat less concerning for rupture compared with more centrally located aneurysms. (See "Overview of aneurysmal disease of the aortic arch branches or upper extremity arteries in adults".)

Quadrilateral space syndrome — The quadrilateral space is the anatomic area through which the axillary nerve and posterior circumflex artery pass and is bounded by the teres minor superiorly, the teres major inferiorly, the long head of the triceps brachii medially, and the humeral neck laterally. This area in the upper arm is created by muscles placed perpendicular to each other around the shoulder joint that work in opposing directions. As such, the structures passing through this space are susceptible to compression and damage, resulting in symptoms related to either nerve- or arterial-related pathology. One study reported that neurogenic compression was more common than arterial compression (1.5:1) [28].

Quadrilateral space syndrome occurs more commonly in males compared with females [28]. The risk is increased with activities involving repetitive overhead arm movement, and usually in elite athletes who have significant muscle hypertrophy in this area. Swimmers and baseball, volleyball, football, and racquetball players have all been described with this pathology. Quadrilateral space syndrome may also occur when other structures/masses occupy this space, including osteochondromas from bony fractures in the upper arm, hematomas from trauma, or fibrous bands.

Damage to the circumflex humeral artery may result in aneurysm formation, within which thrombus may form, resulting in either acute arterial obstruction or distal embolism to the hand. Neurogenic symptoms may arise from compression of the nerve, resulting in positional symptoms. Patients can also have weakness in the muscles affected by this neuropathy, but other muscles in the area may compensate for loss of function, making this a somewhat late finding. Symptoms typically occur during abduction and external rotation of the shoulder, resulting in pain at the shoulder and/or paresthesia in the upper arm.

On physical examination, patients may have sequela of arterial insufficiency (diminished pulses), neuropathic injury (weakness and paresthesias), and tenderness on palpation of the shoulder joint. Placing the arm in flexion, abduction, and external rotation may reproduce the symptoms.

While there is no "gold standard" for diagnosis, imaging with diagnostic angiography, CT/MR angiography, particularly in provocative positioning, may identify compression within the space. Ultrasound has been used to demonstrate muscular atrophy/hypertrophy as well as arterial stenosis or aneurysmal degeneration, as has the use of electromyogram to identify nerve damage.

Treatment is directed toward the presenting symptoms. In most cases, initial treatment includes physical therapy, activity restrictions/modifications, massage/stretching, and use of nonsteroidal medication or steroid injections. If conservative medical management doesn't resolve symptoms, decompression of the quadrilateral space is warranted, with resection of any impinging fibrous bands, debulking the area around the nerve and artery and ensuring a free space through which the neurovascular structures can pass. For patients with aneurysmal degeneration of the circumflex humeral artery with embolism or thrombosis, thrombolysis with reconstruction of the artery may be indicated if signs of ischemia are present.

Hypothenar hammer syndrome — Hypothenar hammer syndrome is a condition that results in digital ischemia following repetitive trauma to the hypothenar eminence under which the ulnar artery travels [29,30].

Hypothenar hammer syndrome can be seen with any activity with recurring forces to the hand [31-33]. In athletes, it has been reported in association with basketball, volleyball, and hockey. The trauma results in intimal damage and either thrombosis of the ulnar artery or aneurysmal degeneration, both of which may result in digit embolism. Classically, aneurysmal degeneration occurs within the superficial palmar branch of the ulnar artery.

The presenting symptoms vary depending upon the extent of arterial damage/thrombosis as well as arterial supply to the hand (collateral vessels present and completeness of the palmar arch) and may include a cool sensation, paresthesias, cyanosis/mottling, or nonhealing digital ulcerations. Patients may also present acutely with hand ischemia, or symptoms can be more indolent. A key finding is that such patients most commonly have unilateral Raynaud syndrome in the dominant extremity. It is important to differentiate these patients from those with Raynaud phenomenon or other disorders that can be associated with hand/digit ischemia.

Noninvasive studies, including duplex ultrasound of the artery as well as digit pressures, may be performed initially; however, the standard for diagnosis is arteriography, which provides the necessary detail of the distal vasculature to diagnose the condition and provide operative anatomical planning for repair. Also, in the setting of acute thrombosis, angiography allows for thrombolysis and may also identify other sources of embolism to the hand.

Management of hypothenar hammer syndrome depends upon the diameter of the aneurysm, expansion rate, and presenting symptoms. There are no well-accepted size or expansion criteria to guide care. Nonoperative treatment for mild cases may include avoidance of trauma, vasodilators (such as calcium channel blockers), antiplatelet agents, and care of any traumatic wounds. Favorable outcomes have been demonstrated in patients treated medically as well as those requiring surgery with moderate improvement in patient-reported functional outcomes. If treated medically, avoidance of repetitive trauma to the hand is critical in achieving success.

For athletes who are symptomatic either because of embolization or mass effect, the aneurysm should be definitively managed. If the athlete presents with digital ischemia, intra-arterial thrombolysis and heparin instillation is reasonable to try and improve outflow as much as possible [13]. For athletes with an ulnar artery aneurysm, resection may be performed to remove the source of embolism. The artery is usually reconstructed with a short vein bypass. If there is robust collateral flow collateral flow from the radial artery and palmar arch to the digits, the hand may tolerate ulnar artery ligation.

Lower extremity

External iliac artery endofibrosis — External iliac artery endofibrosis (EIAE) is a rare form of nonatherosclerotic peripheral vascular disease seen in endurance athletes. EIAE manifests as exercise-induced thigh claudication and is most commonly seen in cyclists, long-distance runners, and speed skaters.

Etiologies and diagnosis — Like other vascular disease processes in athletes, EIAE is due to prolonged and repetitive vascular trauma. The development of EIAE may be related to one of several proposed etiologies, including [6,8,34]:

●Psoas hypertrophy – Hypertrophy of the psoas muscle from intensive training may lead to displacement of the external iliac artery, predisposing the artery to mechanical stress and kinking.

●Arterial fixation or tethering – The external iliac artery is tethered by fascia and muscular slips as it passes under the inguinal ligament. Repetitive trauma caused by this fixation leads to compression, kinking, and the development of endofibrosis within the vessel.

●External iliac artery redundancy – EIAE may also result from abnormal redundancy of the external iliac artery, which predisposes to kinking, flow restriction, and the eventual development of an endofibrotic lesion.

●Paradoxical vasospasm – Increased cardiac output and blood pressure during intense exercise may lead to endothelial injury and the subsequent development of endofibrosis.

●Posture – The aerodynamic posture assumed during competitive cycling or speed skating may stretch the artery, leading to traumatic injury of the posterior wall of the artery predisposing to endofibrosis.

These mechanisms can occur together. In cyclists, the aerodynamic posture unique to cycling leads to the formation of the endofibrotic lesion with progressive stenosis of the lumen, which may be complicated by thrombosis or dissection [8]. Unlike atherosclerotic lesions, endofibrosis involves all layers of the arterial wall and demonstrates a predominance of subendothelial stellate cells and collagen. Various types of arterial histopathology have been described [35,36]. Calcification and lymphocytic infiltration, which is often seen in atherosclerotic lesions, is less common with EIAE.

The diagnosis and timely treatment of EIAE depends upon a thorough history, clinical suspicion, and confirmatory testing with provocative maneuvers [8]. Patients classically present with leg pain or thigh cramping, paresthesias, weakness, or swelling during intensive exercise. The diagnosis of EIAE is often delayed, as these symptoms can be attributed to other musculoskeletal pathologies. The hallmark triad of symptoms described for EIAE is leg weakness, thigh claudication, and resolution of symptoms within five minutes of exercise cessation. Other symptoms may include paresthesias, weakness, or swelling during intensive exercise. Rarely, patients may present with acute limb ischemia secondary to acute thrombosis or dissection. The majority of EIAE patients, however, present with a normal resting vascular exam with palpable pedal pulses.

First-line testing for EIAE consists of noninvasive vascular lab testing. A resting ankle-brachial index (ABI) will generally be normal in these patients. Although there is no specific protocol, exercise testing is performed either on a cycle ergometer or inclined treadmill until symptoms are reproduced. The ABI is taken prior to exercise and at one and five minutes after the onset of symptoms. Per the International Study Group for Identification and Treatment of Endofibrosis (INSITE) collaborators, there is no consensus for an absolute pressure drop that constitutes as a positive result [34]. However, a pressure drop of 21 to 40 mmHg between the affected limb and the contralateral unaffected limb is indicative of EIAE. This testing is specific for EIAE, and exercise diagnostic criteria differ from those used for alternative arterial pathologies. (See "Noninvasive diagnosis of upper and lower extremity arterial disease", section on 'Exercise testing'.)

The diagnosis can be confirmed with duplex ultrasonography, which demonstrates diffuse fibrotic stenosis of the external iliac artery, particularly affecting the posterior wall. Duplex evaluation of the external iliac artery with provocative maneuvers (hip flexion) may also reveal elevated peak systolic velocities consistent with stenosis. CT angiogram, MR angiogram, and digital subtraction angiography are often used as adjuncts to determine the precise location, degree, and distribution of stenosis, and allow for operative planning [34].

Treatment and outcomes — Given the low prevalence of EIAE, there is no definitive algorithm for the management of patients. Treatment should be based on the patient's disease process, degree of limitation, and athletic goals with treatment. Cessation or significant decrease in participation in the inciting sport may prevent progression of disease and may be considered when selecting patients who are willing to give up or significantly decrease intensity of participation in their sport. For cyclists, changing cycling position to decrease hip flexion may also be tried. Generally, consensus is that nonoperative management is not effective in the management of EIAE.

●Open surgical treatment remains the mainstay of treatment for EIAE. The nature of open surgical revascularization depends upon the patient's anatomy, extent of disease demonstrated on preoperative imaging and intraoperatively, and the etiology of the lesion [8,34]. Open surgical techniques for EIAE include endarterectomy and patch angioplasty along the fibrotic portion of the external iliac artery, release of the external iliac artery from tethering bands and/or the inguinal ligament, shortening of redundant portions of the artery, and resection of the fibrotic segment with placement of an interposition bypass.

●Endovascular treatment does not have a role in the treatment of EIAE, as it has not proven to be a good long-term treatment for EIAE. Angioplasty of endofibrotic lesions has been associated with intimal dissection and restenosis due to a high rate of elastic recoil in EIAE [37]. Furthermore, stenting is not recommended; the mechanical forces on the artery can lead to stent fracture or migration.

Reported outcomes vary significantly but are generally favorable in the short term. One study of 300 patients reported 99 percent of patients returning to some level of sporting activity at a mean follow-up of 53 months [38]. A later study reported a decrease from 80.3 percent satisfaction in the short term to 59.1 percent satisfaction in the long term [39]. There is no standardized postoperative recovery, but approximately six to eight weeks of rest is recommended, with gradual resumption of activity after that.

Adductor canal syndrome — Adductor canal syndrome is a rare condition first described in the 1950s. It can occur in young, active patients usually involved in running sports. It is due to external compression from muscle hypertrophy or anomalous fibrous bands that cause occlusive disease of the superficial femoral artery, usually among those involved in running sports.

The adductor (or "Hunter") canal (figure 2) is an aponeurotic tunnel extending from the femoral triangle to the adductor hiatus in the distal thigh. This passageway allows the femoral artery, nerve, and vein to exit the thigh into the popliteal space. It is bounded by the sartorius muscle medially, the adductor longus and magnus posteriorly, and the vastus medialis anteriorly, and is covered by aponeurotic tissue.

Clinical manifestations range from symptoms of claudication to acute limb ischemia depending upon the degree of arterial obstruction [40]. Diagnosis consists of noninvasive vascular laboratory measurements and imaging including CT, MR, or diagnostic angiography. Treatment involves releasing any abnormal bands and repairing the artery with an interposition graft, if damaged.

Popliteal entrapment syndromes — Popliteal entrapment syndrome (PES) refers to a constellation of disorders resulting in the compression of the popliteal artery or vein or both by surrounding musculotendinous structures, particularly during activity. Although PES is relatively uncommon, it is most commonly seen in young, otherwise healthy athletes with a male predominance [41]. Popliteal entrapment is most common in athletes participating in long-distance running, basketball, football, rugby, soccer, and the martial arts [6].

●Arterial PES — The etiology of PES can be congenital due to aberrant relationship of the popliteal artery or vein in relation the leg musculature, or acquired (functional), in which the popliteal muscle is in the normal anatomic position but is compressed by a hypertrophied gastrocnemius muscle. Patients with both congenital and acquired PES classically present with exertional calf pain, or rarely, with acute limb ischemia. Patients will usually have a normal physical exam and diagnostic studies at rest. The diagnosis is established through a combination of imaging tests using provocative maneuvers. For symptomatic patients, surgical decompression of the popliteal space with or without vascular reconstruction is generally recommended.

Outcomes after popliteal release are generally favorable, with studies reporting >75 percent and up to 100 percent of patients with relief of symptoms and/or return to competitive sports [42,43]. Although return to play after treatment for PES depends upon the individual's recovery, athletes should have a rehabilitation program beginning with range of motion and nonimpact rehabilitation followed by gradual advancement to activity. (See "Popliteal entrapment syndromes", section on 'Arterial PES'.)

●Venous PES — Type IV PES describes compression of the popliteal vein, which is most often compressed by the medial head of the gastrocnemius muscle but may also be compressed by a fibrous band. Popliteal venous entrapment should be considered in athletes presenting with symptoms of chronic venous insufficiency with no alternative pathology. The diagnosis of popliteal venous entrapment can be made with duplex ultrasonography with provocative maneuvers. Compared with arterial entrapment, venous entrapment may be treated conservatively with compression hosiery and leg elevation in most cases. In refractory cases presenting with stasis ulceration, surgical release of the popliteal space may be considered. Outcomes of these patients are favorable, with significant relief of pain and swelling and resolution of stasis ulceration/dermatitis in 82 percent of patients [44]. (See "Popliteal entrapment syndromes", section on 'Venous PES'.)

Adventitial cystic disease — Adventitial cystic disease results after formation of unilocular cysts between the adventitial and media layers of arteries from unknown etiology. While adventitial cystic disease is most often described in young, active patients but not particularly related to a specific sporting event, but is should be considered in those presenting with exertional leg symptoms. Adventitial cystic disease most commonly occurs in the popliteal artery, presenting as claudication, but has been described in the external iliac artery, common femoral artery and upper extremity arteries. The diagnosis is made with ultrasonography or other vascular imaging. Treatment has involved cyst aspiration, but more commonly surgical excision with or without arterial reconstruction is performed with good long-term outcomes. (See "Adventitial cystic disease".)

Chronic exertional compartment syndrome — Chronic exertional compartment syndrome (CECS) is a condition seen in athletes in whom increased compartment pressures leads to transient limb ischemia. CECS is most often seen in endurance athletes <40 years of age, particularly long-distance runners, but also athletes in competitive skiing, soccer, basketball, rugby, and tennis. Although the exact etiology is unknown, it is thought that CECS occurs because of a noncompliant osseofascial muscular compartments that are unable to accommodate the expansion of muscle volume that occurs with exercise. During exercise, increased blood flow to the lower leg muscles results in muscle volume expansion. In these athletes, the fascia cannot accommodate the increase in muscle volume, leading to increased intramuscular compartment pressures and development of local tissue ischemia and compartment syndrome. (See "Chronic exertional compartment syndrome", section on 'Definition and pathophysiology'.)

The classic presentation of CECS is seen in a young athlete reporting progressive aching, cramping, or tightness in the anterior or lateral calf during exertion with relief during rest. Reproducibility of symptoms with exertion and complete resolution with rest is a hallmark of CECS in athletes. Symptoms may vary depending on the compartment affected with the anterior compartment (45 percent) and deep posterior compartments (40 percent) most commonly affected [45]. When the anterior compartment is predominantly affected, patients may report paresthesias, numbness of the first web space of the foot, weakness with dorsiflexion, and foot drop. Physical examination is usually unremarkable with palpable distal pulses and intact motor and sensory function at rest. After exercise, the affected compartments may be tense and tender. A diagnosis of CECS can only be made when patients present with reproducible symptoms in the leg, have elevated compartment pressures that remain elevated postexercise, and other possible causes of symptoms have been evaluated and ruled out [46]. Although diagnostic criteria are not defined, the most commonly accepted thresholds for the diagnosis of CECS are a resting compartment pressure of ≥15 mmHg, ≥30 mmHg one minute after exercise, or ≥20 mmHg five minutes after exercise [47]. (See "Chronic exertional compartment syndrome", section on 'Compartment pressure measurement'.)

Initial treatment of CECS consists of conservative therapies including decreasing training intensity, running on softer surfaces that provide more shock absorption, orthotic usage, and physical therapy with a focus on limb stretching or gait training. If a three- to six-month trial of conservative measures is inadequate to provide relief or is unacceptable to the athlete, surgical treatment with compartment release of the involved compartments is indicated. Compartment release can be done via fasciotomy or fasciectomy and in a minimally invasive fashion versus endoscopically. Reported outcomes based upon the technique or method of release are equivocal, so there is no strong evidence supporting any particular surgical technique. (See "Lower extremity fasciotomy techniques", section on 'Alternative fasciotomy techniques for CECS'.)

Approximately 70 to 80 percent of patients have successful treatment defined as return to full activity after compartment release [48]. However, reported success rates are lower in subsets including military personnel, females, cases with the deep posterior compartment involvement. Further research is necessary to improve outcomes in these patients. Postoperative management focuses initially on range of motion exercise and weightbearing followed by a gradual increase to full activity over a period of approximately 8 to 12 weeks [49].

TREATMENT CONSIDERATIONS IN THE ATHLETE — The goal after treatment for most athletes is to return to athletic activity. It is important to develop a structured rehabilitation program to ensure a safe return to sport. The focus of these programs is initially centered on minimizing pain, inflammation, and swelling, then transitions to exercises focused on increased range of motion and strength, and finally progresses to return to sport-specific training. Most structured programs last from weeks to several months based on the athletes' condition and rate of progress [50-52].

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Acute extremity ischemia" and "Society guideline links: Occlusive carotid, aortic, renal, mesenteric, and peripheral atherosclerotic disease" and "Society guideline links: Extremity compartment syndrome".)

SUMMARY AND RECOMMENDATIONS

●Peripheral vascular problems in athletes – Peripheral vascular pathology related to athletic activities comprises a spectrum of disorders that may threaten the athletic career. Repetitive arterial trauma or vascular compression may lead to vascular thrombosis, aneurysmal degeneration, or distal embolism. (See 'Acute limb ischemia' above.)

●Risk factors and mechanisms – The main mechanisms that contribute to peripheral vascular pathology include repetitive upper or lower extremity motions and position-dependent vascular compression, often exacerbated by muscular hypertrophy. Anatomic anomalies, which may be unknown to the athlete, may also contribute. The types of athletic activities involved include (see 'Risk factors and mechanisms' above):

•Upper extremity

-Baseball, softball

-Swimming

-Water polo

-Rowing

-Volleyball

-American football

•Lower extremity

-Running

-Skiing

-Basketball

-American football

-Martial arts

-Bicycling

●Vascular symptoms – The clinical presentation is often acute but can be more chronic. Classic manifestations of acute limb ischemia are due to sudden arterial occlusion or distal embolism, or rarely from extensive venous occlusion. Chronic symptoms may include exertional pain or early limb fatigue, extremity swelling, skin discoloration, or other skin changes. (See 'Vascular symptoms' above.)

●Vascular evaluation – The diagnosis of a vascular etiology for presenting symptoms is often overlooked, with extremity symptoms often initially attributed to musculoskeletal injury. Thus, it is important to maintain suspicion for vascular pathology in athletes to avoid the consequences that may delay a return to competition. Clinically, differentiating between musculoskeletal injury and vascular pathology relies on performance of a complete vascular physical examination and using provocative maneuvers. Obliteration of a pulse or onset of limb fatigue during provocative maneuvers should raise clinical suspicion for arterial etiology. Vascular evaluation and imaging (duplex ultrasound, CT/MR imaging, catheter-based angiography) confirms the diagnosis and can also be done with the limb in different positions. (See 'Vascular evaluation' above.)

●Specific vascular pathologies – Specific vascular pathologies are reviewed in the sections above, including those that predominantly affect the upper extremity, such as thoracic outlet syndrome (TOS), aneurysmal disease including hypothenar hammer syndrome, quadrilateral space syndrome, and those that affect the lower extremity including external iliac artery endofibrosis (EIAE), adductor canal syndrome, popliteal entrapment syndrome (PES), adventitial cystic disease, and chronic exertional compartment syndrome (CECS). (See 'Specific disorders' above.)

●Return to athletic activity – The goal after vascular treatment for most athletes is to return to athletic activity. The focus of structured rehabilitation programs is to ensure a safe return to sport. Most structured programs last from weeks to several months based on the athletes' condition and rate of progress. (See 'Treatment considerations in the athlete' above.)