Popliteal Artery Entrapment in a Classical Ballet Dancer: Successful Conservative Management.

Abstract

Introduction Popliteal artery entrapment syndrome (PAES) is an important differential diagnosis for exertional leg pain. PAES presents when anomalies in the anatomical relationship between the popliteal artery and the medial head of the gastrocnemius muscle (MHGM) exist (7). This leads to a restriction in popliteal arterial flow to the neuromuscular structures of the leg, resulting in the pain and claudicant symptoms described by patients. Several excellent descriptions of the embryological development of the popliteal artery and MHGM as well as the anatomy of the region exist (4,5,104,5,104,5,10), to which the interested reader is referred. The most commonly used classification system for PAES describes six types. The initial classification system for PAES described four types and was introduced by Delaney and Gonzales in 1971. Types 5 and 6 were added on at a later stage (2). The first five represent variations on the anatomical position of the popliteal artery and the MHGM with respect to each other, and the sixth is known as functional PAES (10). It is generally agreed that symptomatic anatomical PAES (Types 1 to 5) requires investigation with magnetic resonance angiography (MRA), catheter-directed contrast angiography, duplex ultrasound (10), and consideration of surgical repair. This is necessary to reduce and limit long-term damage to the popliteal artery. Anatomical PAES is considered a progressive disease leading to arterial intimal damage, causing stenosis, thromboembolic disease, and aneurysm (1,3,4,9,121,3,4,9,121,3,4,9,121,3,4,9,121,3,4,9,12). Surgery is usually described as MHGM myotomy and/or relocation and popliteal artery repair or bypass graft (7). Functional PAES exists when claudicant symptoms from popliteal artery occlusion occur with provocative exercise (10) yet the anatomy of the popliteal fossa is normal. The best treatment approach for functional PAES has not yet been established and is the subject of much debate (5,6,95,6,95,6,9). The population typically affected by functional PAES will be younger and more athletic and will have a higher proportion of females than in anatomical occluders (4). Case Presentation The patient is a 24-year-old elite classical ballet dancer presenting with bilateral exertional posteromedial leg pain and paresthesias into the plantar aspect of both feet persisting for more than 4 years. Over the preceding 8 months, the pain had significantly increased on the right side in association with an increased training load. The pain would crescendo over a period of a few minutes of intense calf work and dissipate in minutes with rest and leg elevation. The patient had 19 years of total dance training, with 6 years at the elite level. Medical history revealed many episodes of varying types of exertional leg pain during this period. She is able to distinguish different types of pain and gives a clear history of medial tibial stress syndrome (MTSS) bilaterally and posterior ankle impingement on the right. Surgical history was significant for a right ankle os trigonum excision. Examination Upon observation, there was mild wasting of the right MHGM and bilateral genu recurvatum. With a vascular provocation test, there was reproduction of a popliteal bruit with associated pain and loss of distal pulses. The provocation test was conducted by examining the patient at rest — palpation of peripheral pulses and auscultation over the popliteal fossa. They then performed up to 20 controlled heel drops off the edge of a step on each leg. Palpation of the peripheral pulses and popliteal fossa auscultation are repeated. A positive test result is determined by reproduction of the patients’ symptoms and development of an audible bruit. Typically, there is loss of the peripheral pulses. Doppler ultrasound examination revealed there was normal resting velocity in the popliteal artery, but dynamic assessment involving resisted gastrocnemius activity revealed there was bilateral occlusion of the popliteal arteries. This finding led to a magnetic resonance imaging scan (Fig. 1) that showed the MHGM to be laterally located and displacing the popliteal arteries against the lateral femoral condyles. A functional MRA (Fig. 2) also demonstrated complete occlusion of the popliteal arteries between MHGM and the lateral femoral condyle as well as deep to the plantaris muscle. There was no evidence of intimal damage to the popliteal arteries.Figure 1: MRI scan showing the MHGM to be laterally located and displacing the popliteal arteries against the lateral femoral condyles.Figure 2: Functional MRA demonstrates complete occlusion of the popliteal arteries between MHGM and the lateral femoral condyle as well as deep to the plantaris muscle.Management In this patient, nonoperative management has focused on the medial tibial pain, including calf stretches and specific soft tissue mobilization techniques. Traditionally, strengthening the calf musculature to improve ground reaction force absorption for landing is used as part of MTSS rehabilitation. In a dancing population, calf strength is paramount to the performance of the classical technique and calf rises in addition to class is a consistently used approach to protect dancers from injury. This presents a problem when dealing with PAES, as strengthening the gastrocnemius may further exacerbate claudication symptoms. It is possible that in our patient, the additional strengthening following ankle surgery contributed to worsening symptoms. To help resolve this paradox, the patient has learned to actively relax her gastrocnemius muscle even on stage. Controlled concentric and eccentric contractions of the gastrocnemius muscles (rising onto pointe and lowering slowly) elicit symptoms; however, “locking” into full plantarflexion reduces symptoms by allowing her to relatively relax the gastrocnemius muscles in this position. This presumably reduces the occlusion of the popliteal arteries by assuming a static ligamentous hold for the joint rather than dynamic muscle action. It also may preferentially recruit the hamstring muscles to control and maintain knee extension. Other modifications were slowing down footwork, performing shorter exercises, taking short (1 to 2 min) breaks between exercises, and elevation of the feet. Maintaining strong intrinsic musculature in the foot is also paramount to optimizing the position and control of the ankle and foot. Regular release work for the calf musculature and the application of therapeutic ultrasound (at 1 MH, continuous, 1.0 W·cm−2, 3 min each side), also have proven beneficial. The patient reports significant pain reduction for 4 to 6 h afterwards. Finally, ongoing communication with the Dance Company artistic staff and management is as important as physical rehabilitation for the dancer. For the dancer to be able to modify class, technique, body conditioning, and performance as required is integral to successful treatment, and it is our opinion that without this, success would be impossible. Discussion In PAES, popliteal artery flow becomes reduced or occluded in the course of usual activity in patients with no risk factors for vascular or atheromatous disease (1). PAES is an important differential diagnosis for patients presenting with exertional leg pain and is of particular importance in a young athletic population (4). There is considerable overlap in symptomatology with chronic exertional compartment syndrome, and it is possible that the two conditions may coexist. In recent years, there has been much interest in the syndrome as evidenced by a growth of research literature on the subject (2–5,72–5,72–5,72–5,72–5,7). Operative management in functional PAES is not considered as successful as that for anatomical PAES and is untested in a dancing population (10). Nonoperative management options have not been described. For dancers, extreme ankle range and repetitive loaded plantarflexion are integral parts of their sports. A strong and supple triceps surae is necessary to this. Existing literature largely recommends a surgical approach to management, although outcomes in functional PAES are not as positive as those for anatomical PAES (3,103,10). Given the possibly extensive nature of the surgery and the potential for complications, recommending surgery in functional PAES should not be undertaken lightly (3). No previous study or report has considered this in dancers. There is suggestion that MHGM hypertrophy in athletes can contribute to arterial occlusion (7,137,13). This has not been confirmed with imaging studies (11). Paradoxically, our patient has a relatively smaller MHGM on the more severely affected side. The most comprehensive imaging study to date (11) imaged the limbs of 10 occluders and 10 nonoccluders and found a tendency for the MHGM to attach more superiorly and laterally on the medial femoral condyle in occluders. Unfortunately, the authors excluded athletes and anyone who exercised more than three times a week, thereby excluding those who might be more likely to have MHGM hypertrophy. In classical ballet, a core skill for female dancers is to dance en pointe in extreme plantarflexion. The muscular control required to move in and out of the full pointe position smoothly is a hallmark of an elite ballet dancer. Another is the ability to jump high and repetitively, with fast footwork and full ankle and foot plantarflexion in the air. Because of these requirements, it remains to be seen whether PAES in the patient described will affect the longevity or success of her career. The fact that this patient has been able to continue to such a high level may suggest adaptations over time with her pain threshold and coping mechanisms. Overall, our success so far in managing the patient is measured by the following: reduction in pain when dancing/training; reduction in pain after training or performing; ability of the patient to maintain ongoing requirements of professional ballet occupation; aim to assist the patient to train and perform in as many performing “roles” as possible. So far, all roles in which the patient has been cast have been possible for her, with one exception (a role that involved continuous jumping and pointe with no breaks for 20 min); monitoring the patient symptomatically; it remains uncertain as to whether patients with functional PAES are at increased risk of early intimal damage. Repeat MRA would not be justified if symptom control is adequate; and supporting the patient mentally (and physically) to cope with PAES in a demanding physical career; Conclusions This case study has illustrated the use of nonsurgical treatment and physical rehabilitation to enable an elite classical dancer with MRA-proven PAES to continue to train and perform at the highest level. It is the first report in the literature to do so, and it is encouraging for those working with athletes, recreational and elite, experiencing PAES that an alternative to extensive surgery or activity cessation is possible. The authors declare no conflicts of interest and do not have any financial disclosures.