A novel approach to the treatment of functional popliteal artery entrapment syndrome in college athletes

Abstract

Background

Functional popliteal artery entrapment syndrome (FPAES) is a rare disorder that results from hypertrophy and overuse injury of calf muscles, which thereby compress neurovascular structures in the popliteal fossa. The majority of FPAES cases are found in young athletes who present with symptoms during exercise. Most commonly, FPAES is surgically treated with muscle debulking utilizing a posterior S-shaped incision, but wound healing and neuropathy remain problematic in this approach. Here, we present our case series of college athletes undergoing FPAES repair using a novel medial calf approach that avoids surgical incision across the joint space.

Methods

This is a retrospective analysis of all FPAES repairs performed at our institution from 2016 to 2023. The popliteal fossa was entered by a 10- to 12-cm incision on the medial aspect of the calf. Exploration of the popliteal artery, vein, and neurovascular bundle was performed. Tenotomy of the soleus and tenotomy and debulking of the medial gastrocnemius were performed. We studied postoperative wound complications, pain, neurovascular symptoms during in-hospital and long-term follow-up periods, postoperative analgesia use, length of stay, pre- and postoperative ankle brachial indices (ABIs), and lower extremity arterial duplex.

Results

Twenty-four patients were included, 23 of whom underwent bilateral repair (47 limbs total). The mean age was 21.9 years (standard deviation, 7.7 years). Most patients were female (83.3%), and all patients reported exercise-induced lower extremity pain. Most patients had a reduction in preoperative ABI after exercise (mean preoperative resting ABI, 1.19; mean preoperative exercise ABI, 0.94). Lower extremity arterial duplex revealed a nearly two-fold increase in mean blood velocity among patients after exercise (mean velocity at rest, 65.8 cm/s; mean velocity during plantarflexion, 120.9 cm/s). Nine patients (36.2%) had prior operations related to exertional compartment syndrome in the lower extremities. The median length of stay was 1 day. Postoperative exercise ABI showed marked improvement compared with preoperative values in all athletes. Twenty-one of 24 patients (87.5%) resumed competitive sports without restriction at a median of 59 days after surgery. Of the three patients who did not return to competition, one died of an unrelated malignancy, and two had symptomatic recurrences that were subsequently treated for causes other than FPAEs.

Conclusions

We demonstrate favorable clinical and hemodynamic results and a low rate of complications for release of FPAES utilizing the medial approach. This surgical approach avoids the complications of delayed wound healing and neuropathy inherent to the posterior approach and may provide comparable functional outcomes for patients with FPAES.

Article Highlights.

• •Type of Research: Single-center retrospective cohort study
• •Key Findings: Twenty-four patients (47 limbs) underwent surgical repair for functional popliteal artery entrapment syndrome using the medial approach, and only one patient (4.2%) reported postoperative wound complications. At a median follow-up time of 59 days, 21 of 24 patients had returned to activity without restriction.
• •Take Home Message: The medial approach achieves comparable outcomes to the traditional approach in treating functional popliteal artery entrapment syndrome with a low rate of postoperative complications, even in populations with previously failed posterior decompression.

Popliteal artery entrapment syndrome (PAES) is a disorder that results from entrapment of the popliteal artery by surrounding structures as it courses through the narrow popliteal space. PAES manifests with many types of symptoms, such as claudication, calf pain, calf tightness, or paresthesia.^1,2 Symptoms often present or worsen significantly during exercise. Muscles require greater perfusion during exercise; therefore, any obstruction in the flow of the popliteal artery can lead to symptoms. PAES can be caused by anatomic variations congenitally present in the popliteal region itself (anatomic PAES) or due to compression by adjacent structures caused by hypertrophy and overuse injury of the calf muscles (functional PAES [FPAES]).3, 4, 5, 6, 7, 8

FPAES is a rare and difficult diagnosis, most commonly observed in young collegiate and professional athletes.^7,9 The often highly developed musculature in athletes can promote occlusion of the popliteal artery in the intercondylar space or between the two heads of the hypertrophied gastrocnemius, resulting in symptoms. Athletes typically lead physically intense lifestyles, so symptoms often manifest early and worsen with strength training.

A number of management approaches are available, and, generally, early detection and aggressive treatment have been recommended.¹⁰ Surgery releasing the underlying entrapment is accepted as the gold standard of treatment, particularly in the younger population. There is consensus that failure to treat FPAES either results in lowering the level of sport competition or abandonment of the endeavor.¹¹ In the most extreme scenarios, there is a concern for chronic injury to the neurovascular bundle, chronic pain, and thrombosis requiring bypass surgery.¹² Despite treatment, it can be challenging to achieve complete symptomatic resolution and maintain durable outcomes. Cabot et al describe a 20-year series in which 11.2% of limbs demonstrated symptomatic recurrence at a median follow-up of 369 days, highlighting the challenges in attaining lasting, favorable outcomes.¹³

Although prior literature regarding FPAES has highlighted several surgical approaches, there remains ambiguity in terms of the surgical technique resulting in optimal outcomes.^13,14 A posterior-based approach with an S-shaped incision is most commonly used to treat both the anatomic and functional varieties of PAES.¹³ However, this approach has disadvantages to wound healing and neuropathy. The medial approach is also used, but more commonly when bypass of vessels is required. Here, we present our case series on the medial-based approach for FPAES repair in an exclusive cohort of young intercollegiate and professional athletes.

Methods

We performed a retrospective chart review of all patients undergoing surgical treatment for FPAES at our institution from 2016 to 2023. All cases were performed by the senior author (J.B.). We recorded age at the time of surgery, as well as gender, race, comorbidities, and smoking status. The primary type of physical activity for each patient was also recorded. The following FPAES-specific information was also recorded: laterality, preoperative symptomatology (pain, paresthesia, limb discoloration, and swelling), preoperative imaging, and ankle brachial index (ABI) values at rest and after exercise. The study was approved by the Johns Hopkins institutional review board. The need for individual patient consent was waived because this was a retrospective chart review. All identifiable protected health information was deidentified prior to analysis, ensuring that no individual could be identified from the data which we present.

Diagnosis

FPAES was diagnosed with a combination of history, physical exam, ABIs, and imaging. Diagnostic criteria included a decrease in ABI upon functional testing, radiologic evidence of arterial compression on duplex ultrasound, and cross-sectional imaging demonstrating evidence of medial gastrocnemius hypertrophy. Imaging was performed with a combination of imaging modalities. All patients had their ABI measured pre- and postoperatively at our institution if under our management at those stages. Patients for whom data was unavailable were accordingly excluded from statistical analysis performed in this study. The patient was laid flat in the supine position. Continuous wave Doppler analysis (minimum carrier frequency of 3.0 MHz) was obtained bilaterally at the posterior tibial and dorsalis pedis arteries at a 45-degree angle to the skin or area of insonation. A minimum of three representative waveforms were obtained for each vessel with standardized gain settings. If no posterior tibial or dorsalis pedis signals were found, the anterior tibial and peroneal artery were measured. The ABI was then calculated by dividing the highest ankle systolic blood pressure by the highest brachial systolic blood pressure. ABI was measured at rest (resting ABI) and after walking or running on a treadmill until PAES symptoms manifested (exercise ABI).

Similarly, duplex testing was performed preoperatively to assess waveform patterns and document flow velocities in the popliteal and pedal vessels. Duplex testing was performed at rest and after walking or running on a treadmill to evoke symptoms. Patients were instructed to set the treadmill to a moderately challenging speed and perform the exercise until symptoms were induced. After symptoms manifested, the patient was instructed to stand on their tiptoes to forcefully maintain plantarflexion during completion of the symptomatic duplex. Transverse still images and cinematic clips of the popliteal artery and vein were captured. Doppler waveforms and velocity measurements were recorded above and below the knee in the popliteal artery, and at the level of the tibioperoneal trunk. If tibioperoneal trunk signals were not found, the dorsalis pedis arteries were measured.

Other imaging techniques performed to confirm diagnosis were also recorded. These included computed tomography (CT), magnetic resonance imaging (MRI)/magnetic resonance angiography (MRA), intravascular ultrasound (IVUS), and angiography. Similar to ABI and duplex testing, these techniques were performed at rest and repeated after exercise to confirm the FPAES diagnosis and rule out other etiologies.

Since 2023, IVUS was employed as an adjunctive imaging modality in cases where further evaluation was required after standard diagnostic testing. IVUS imaging was performed under moderate sedation. Dynamic angiography of the popliteal region was performed with the patient in a neutral position using conventional techniques. The patient was then instructed to plantarflex against resistance using a strap until symptoms manifested, and repeat angiography was performed. Compression was characterized by luminal narrowing and delayed flow. IVUS was incorporated into the surgical planning protocol for FPAES at our institution in 2023. This procedure was performed using an Eagle Eye Platinum IVUS catheter (Koniklijke Philips). The popliteal artery was interrogated with IVUS during neutral and active plantarflexion. Compression was characterized by circumferential or eccentric deformation of the arterial lumen and changes in cross-sectional area. The superior and inferior extents of narrowing found on IVUS were marked by fluoroscopy. In cases where bilateral extremities were assessed, the vascular sheath access was flipped, and the contralateral popliteal artery was interrogated.

Operative technique

After the patient was anesthetized, prepped, and draped, a 10- to 12-cm incision was made along the medial aspect of the calf. A combination of sharp and electrocautery dissection was performed until the fascia of the superficial posterior compartment was identified. This was then opened in a longitudinal fashion, and structures of the popliteal fossa were identified. Any scar tissue from prior repairs was carefully dissected. Next, inspection of the popliteal artery, vein, and neurovascular bundle were performed from the level of the femoral condyles to their entry under the soleus. Attention was paid to any muscle slips or tendons intervening between the artery and vein that may have been missed by MRI assessment. Then, electrocautery was used to perform the deep posterior compartment release down to the level of the trifurcation vessels. In cases where popliteal fossa structures were compressed by the soleus, a decompressive fasciotomy and tenotomy of the deep posterior compartment were performed to ensure that the entirety of the below-knee popliteal vessel into the tibioperoneal trunk was appreciated and decompressed. Enough space was created for a finger to pass through the space underneath the soleus muscle. After checking hemostasis, exploration and lysis of the popliteal artery continued proximally to the area of the femoral condyles. After entering the popliteal region, the unimpeded course of the vessels was appreciated. Involvement of the gastrocnemius was evaluated by taking the leg back into a straight position and noting the proximity of the hypertrophic medial head of the gastrocnemius to the neurovascular bundle. Debulking of the muscle was performed using a ring clamp to grasp portions of the lateral aspect of the medial gastrocnemius muscle, where it directly opposed the neurovascular structures. The process of debulking the medial gastrocnemius muscle, via grasping it with a ring clamp and resecting with cautery, was performed stepwise, proceeding from the proximal to distal through the fossa. The blood supply to the gastrocnemius muscle via its branches from the popliteal artery was carefully preserved. A drain was placed in the popliteal fossa to collect any leakage. The fascia of the posterior compartments was not closed. The skin was closed in layers of vicryl sutures and a subcuticular stitch, and a compression bandage was applied (Figs 1 and 2). In cases of bilateral involvement, approximately 2 weeks were allotted between operations to facilitate adequate interval recovery.

Fig 1.

Intraoperative photo. The incision was made along the medial aspect of the left calf, showing retraction of the medial gastrocnemius and resection of the hypertrophied muscle to decompress the neurovascular bundle (dashed yellow arrow). Forceps are placed on the medial gastrocnemius (solid yellow arrow). This intraoperative photo was included in this manuscript with patient permission.

Fig 2.

Locoregional anatomy and surgical procedure in patients with functional popliteal (pop) artery entrapment syndrome (FPAES). Posterior and medial views (A and B) of the musculoskeletal and neurovascular anatomy of patients with FPAES. Medial (med) incision with retraction of the gastrocnemius (gastroc) and exploration of the pop neurovascular structures (C and D). A, artery; V, vein. Debulking and fasciotomy are performed on the med head of the gastrocnemius muscle approximately along the dotted black line to alleviate pop artery compression (E). Fib, Fibula; Lat, lateral.

Outcomes of interest

This study’s outcomes of interest were the length of stay, need for analgesia, perioperative and postoperative complications (including pain, wound complication, and paresthesia), long-term complications, and postoperative time until functional return to activity. Patient outcomes were documented at the following intervals: in-hospital during treatment, at the time of their first follow-up visit, and long-term.

Statistical analysis

Data were collected in a Microsoft Excel (Microsoft Office Professional Plus 2016) spreadsheet and tabulated. Categorical variables were reported as frequencies and percentages, and continuous variables were reported as either mean with standard deviation (SD) or median with interquartile range (IQR). All analyses were performed using Stata 14 (StataCorp).

Results

Twenty-four patients underwent repair (47 limbs) for FPAES, 23 of which were bilateral. The mean age was 21.9 years (SD, 7.7 years). Nine patients (17 limbs) had a history of prior surgery for PAES or compartment syndrome, which included fasciotomies and/or popliteal exploration. Only one of these nine patients (2 limbs) was treated for PAES, and the remainder were treated for compartment syndrome. None of the patients had major comorbidities such as diabetes, hypertension, chronic obstructive pulmonary disease, and coronary artery disease. None of the patients reported a history of smoking. Most of the patients were female (83.3%) and White (91.5%). All patients had a preoperative diagnosis of FPAES. All patients were active in collegiate or professional sports, and the most common type of activity was soccer (59.6%). All patients had preoperative pain (100%) with exercise. Six patients (25%) reported preoperative paresthesia. Limb discoloration and limb swelling were observed in three and four patients, respectively. Detailed patient characteristics are listed in Table I.

Table I.

Patient characteristics

Demographics and history	Data
Sex
Male	4
Female	10
Laterality
Unilateral	1
Bilateral	23
Total limbs	47
Preoperative symptoms
Pain	47 (100)
Swelling	4 (8.5)
Discoloration	3 (6.4)
Paresthesia	6 (25)
Preoperative Imaging
Computed tomography	1 (2.1)
Magnetic resonance imaging	12 (25.5)
Duplex	47 (100)
Preoperative vascular physiological parameters	1.186 (0.08)
Resting ankle-brachial index	0.943 (0.17)
Exercise ankle-brachial index	65.8 (19.2)
Resting popliteal peak systolic velocity, cm/s	120.9 (41.9)
Forcible plantarflexion peak systolic velocity, cm/s

Data are presented as number, number (%), or mean (standard deviation).

All patients (100%) underwent preoperative duplex imaging at our institution to confirm the FPAES diagnosis. Six patients (25%) had a preoperative MRI, six patients (25%) had a preoperative MRA, and one patient (1 limb) had a preoperative CT. All patients (100%) had a reduction in ABI with exercise before operation (mean preoperative resting ABI, 1.186 [SD, 0.079]; mean preoperative exercise ABI, 0.945 [SD, 0.17]). Preoperative lower extremity arterial duplex revealed a near two-fold increase in mean popliteal peak systolic velocity among patients after exercise (mean velocity at rest, 65.8 cm/s [SD, 19.2 cm/s]; mean velocity during plantarflexion, 120.9 cm/s [SD, 41.9 cm/s]).

All 24 patients (100%) were operated under general anesthesia, and a drain was placed in the popliteal fossa for 23 patients (95.8%). Intraoperative blood loss was minimal—less than 50 mL—in all but one patient (1 limb). One patient (4.2%) developed mild rubor at the incision site within the perioperative period. For postoperative pain relief, opioids (oxycodone or tramadol) were prescribed to 79.2% of patients, and nonopioid analgesics (nonsteroidal anti-inflammatory drugs or acetaminophen) were prescribed to 87.5% of the patients. The median length of stay was 1 day (IQR, 1 day).

Twenty-one of 24 (87.5%) patients resumed competitive sports without restriction on the mid-term follow-up at a median of 59 days after surgery. Of the three patients who did not resume competition, two experienced symptomatic recurrence, and one passed away due to an unrelated etiology. Both patients with symptomatic recurrence were then treated for non-FPAES etiologies after. The first of these two patients had unilateral leg pain, which was sharp in nature and diagnosed as peroneal nerve entrapment. This patient was referred to a peripheral nerve specialist for further management. The second patient presented with bilateral lower calf pain in the area overlying the Achilles tendon. Duplex testing at rest revealed no arterial compression, and the patient was referred to orthopedics. Long-term follow-up data for these two patients is lacking as they were shortly referred to external institutions for further management.

A total of six patients (8 limbs) reported postoperative leg pain at a median of 66 days after surgery (IQR, 29 days). Two of these patients’ pain resolved on its own, one patient was referred to an external institution close to their residence, and three of them required further management at our institution. The two aforementioned patients treated for non-FPAES etiologies who did not return to competition account for two of these three patients. The third patient reported bilateral pain, rubor on dependency bilaterally, and paresthesia with normal ABI on the long-term follow-up. This patient was referred to a peripheral nerve specialist for further evaluation and management. No patient reported wound complications in the long-term follow-up. Patient outcomes are listed in Table II.

Table II.

Patient outcomes

Outcome	Data
Length of stay, days	1
Postoperative symptoms
Pain	6 (25)
Numbness	4 (16.7)
Burning	2 (8.3)
Wound complications	1 (4.2)
Analgesia use
Opioids	19 (79.2)
Nonsteroidal anti-inflammatory drugs	21 (87.5)
Functional outcome
Return to activity	21 (87.5)
Time to return, days	59

Data are presented as number (%) or median.

The mean postoperative resting ABI was 1.183 (SD, 0.088) based on 38 limbs, which showed no remarkable change from the preoperative resting ABI of 1.186 (SD, 0.079). However, a significant improvement was observed in the postoperative exercise ABI. The mean postoperative exercise ABI was 1.046 (SD, 0.151) based on 32 limbs, marking a significant improvement (P = .0083) from the preoperative exercise mean ABI of 0.945 (SD, 0.17) (Table I and Fig 3).

Fig 3.

Ankle brachial indices (ABIs) measured pre- (pre-op) and postoperatively (post-op), at rest and after exercise. A decrease in pre- and postop ABI was observed with exercise, but the drop was attenuated after surgery. The mean preop exercise ABI was 0.945 with standard deviation (SD) of 0.17, whereas the mean postop exercise ABI was 1.046 with SD of 0.151 (P = .0083).

Discussion

In our study of repair of FPAES in 24 patients (47 limbs), we found the medial approach to have favorable outcomes. Most patients did not have any postoperative wound complications, and most had a length of stay that did not exceed 24 hours. All patients remaining under our management after surgery recovered in terms of pain, neurovascular symptoms, and leg mobility and successfully returned to their previous level of activity. To confirm the diagnosis, all patients in our cohort underwent ABI testing—resting and postexercise—before and after surgery. There was a remarkable increase in mean postoperative exercise ABI compared with preoperative exercise ABI (1.046 vs 0.945; P = .0083). As 37.5% of the cases in our series were revisions after failed posterior surgical exposures, we found the medial approach favorable in this population as well.

The term PAES was first used by Whelan et al in 1965, although Stuart described variations in the course of the popliteal artery in 1879.^15,16 PAES remains an under-reported but common cause of atypical claudication. As PAES is not commonly diagnosed, its prevalence in the general symptomatic population remains unclear. Relative to the anatomic subtype, FPAES is even rarer.¹⁴ A study done on patients presenting with calf pain (1987-2000) found FPAES to be present in 12.5% of patients, whereas 85% of patients had compartment syndrome.¹⁷ Management options include conservative or medical treatment, surgery, and physical rehabilitation.^14,18 Conservative options, including botulinum toxin injection, have shown mixed results.¹⁹ There seems to be general agreement on surgery as the preferred option for optimal long-term outcomes when treating FPAES. Surgery typically entails a release of the calf muscle, and bypass is rarely necessary. Interestingly, surgery is regarded as both diagnostic and therapeutic for FPAES by some authors.²⁰

Despite its rarity, some authors from high-volume centers have published their case series of PAES treatment. The case series by Corneloup et al presented an 11-year experience with 61 legs, commenting on the challenges to diagnose and treat PAES.¹¹ Gourgiotis et al reported their experience of 38 patients with 49 PAES limbs treated surgically with 1-year patency of 100%.²¹ Sinha et al reported a systematic review from 1947 to 2010, reporting 28 studies with a median of 15.5 limbs.¹⁴ Turnipseed described a large series of FPAES treatment cases using a similar medial approach, achieving favorable outcomes.¹⁷ Others have also mentioned the medial approach, although it was typically reserved for cases where bypass is needed.¹ These papers have a sizable number of patients and discuss the challenges regarding diagnosis and treatment of PAES. However, preference of one surgical approach to another has not been discussed.

Among the surgical approaches for PAES repair, the posterior S-shaped incision is most common. However, there are inherent complications due to the creation of extensive cutaneous flaps. This may increase the risk of wound complications and require a stronger and prolonged need for analgesia. In contrast, our proposed medial approach involves a smaller incision length, thereby potentially reducing wound complications and need for analgesia. In our cohort, only one patient experienced minor wound complications during the perioperative period, and most had a length of stay of 1 day.

The traditional posterior approach requires incision at a mobile area of the knee, which can complicate wound healing. Collegiate athletes who are affected by FPAES often have scholarships contingent on excelling in sports, and therefore, returning to competition is an important concern. The medial approach may offer faster recovery and earlier mobility due to the incision being made in a less mobile area than the posterior approach (inferomedial to knee). As shown in our study, of 22 athletes who had long-term follow-up, 16 had successfully returned to their previous level of activity without pain at a median of 387 days after surgery. Although these short-term results are encouraging, further study is needed to determine durability at 3 and 5 years and later time points.

FPAES can be a challenging diagnosis due to the symptomatic overlap with other compression syndromes commonly seen in athletes.^1,6,7 In our series, no patients had compartment pressure testing performed. However, in our cohort, eight had prior diagnoses and management for compartment syndrome, and the remaining 16 patients demonstrated robust evidence of functional popliteal artery compression during diagnostic imaging. Furthermore, patients presenting for FPAES repair have often undergone prior surgery to the calf for similar symptomatic presentations. FPAES repair may require subsequent revision, as persistent physical activity can lead to recurrence of muscle hypertrophy and entrapment symptoms.²² In fact, 37.5% of the cases in our cohort were revision procedures, and we still achieved favorable outcomes. For these reasons, we advocate for the medial approach in revision cases to avoid scar tissue from prior posterior repair, and in new cases where preservation of posterior fossa may be beneficial in the event that revision is required. Furthermore, the medial incision may offer a more desirable cosmetic profile.

As the medial incision enters the popliteal area from the side, the exposure of musculotendinous anatomy is limited compared with the traditional posterior approach.¹⁴ This may increase the complexity of the approach, rendering this a limiting technique that only surgeons experienced in this repair can perform. Moreover, not all types of popliteal entrapment can be treated through this approach.

There are both strengths and limitations to our study. To the best of our knowledge, this is the largest study of its kind outlining the medial approach in college athletes presenting with FPAES. The data presented is contemporary, and a number of modern diagnostic tools, including duplex, CT angiography, and MRA, were employed to confirm the diagnosis of FPAES. The limitations include the retrospective nature of our study and the lack of a comparison control group. Additionally, our study lacks long-term follow-up data for some of the patients. Long-term follow-up is important, as patients with FPAES often have recurrence of symptoms and achieving durable outcomes remains challenging. Additionally, optimal rehabilitation strategies for this patient group are not known. Our rehabilitation plan was recommended to our patients, yet we cannot ascertain adherence given the wide referral base (Supplementary Table and Supplementary Figs 1-3, online only). There remains a need for a multicenter, prospective study to further establish the optimal approach to treat FPAES.

Conclusions

We demonstrate favorable results and a low rate of complications for the release of FPAES utilizing the medial approach. This surgical approach was associated with improvement in postexercise ABI, a return to competitive sports, and durable outcomes. This technique avoids the frequent complications of wound infection and neuropathy inherent to the posterior approach and may provide comparable hemodynamic outcomes for patients with FPAES. However, patient failures can still occur, both clinically and hemodynamically, suggesting a need for further refinement of treatment and rehabilitation strategies.

Author Contributions

Conception and design: JB

Analysis and interpretation: CS, MM, JB

Data collection: CS, MM, JB

Writing the article: CS, MM, JB

Critical revision of the article: CS, MM, JB

Final approval of the article: CS, MM, JB

Statistical analysis: CS, MM, JB

Obtained funding: Not applicable

Overall responsibility: JB

Funding

None.

Disclosures

None.

From the Southern Association for Vascular Surgery

Appendix (online only)

Supplementary Fig 1.

Supplementary Fig 2.

Supplementary Fig 3.