Tibial Artery Stent Deformations From Ankle Plantarflexion and Dorsiflexion, Knee Flexion, and Simulated Calf Muscle Contraction

Background

Tibial artery stent deformations have not been previously published and are critical for the evaluation and development of below-the-knee treatments.

Methods

Balloon-expandable stents were implanted into the anterior tibial, posterior tibial, and peroneal arteries of cadaver legs, including ostium-crossing locations. Computed tomography and geometric modeling were used to quantify cross-sectional, axial, and bending stent deformations from ankle plantarflexion/dorsiflexion, knee flexion, and simulated calf muscle contraction for walking/running.

Results

Single and overlapping stents (N = 53) were deployed into 23 tibial arteries and across 6 ostia. Diametric crush was experienced in the posterior tibial with knee flexion (–5.3% ± 3.2%, P < .0001) and peroneal with ankle dorsiflexion (–2.4% ± 2.0%, P = .0016), and posterior tibial stents experienced greater diametric crush from knee flexion (–5.3% ± 3.2%) and calf compression (–3.4% ± 5.9%) compared to ankle motion (–0.2% ± 4.3%; P = .0009 and P = .0061, respectively). Ostium-crossing stents experienced order of magnitude higher axial shortening with knee flexion and ankle plantarflexion compared to those in single arteries. No stent bending was observed from any leg motion.

Conclusions

Diametric crush in posterior tibial and peroneal stents was potentially due to their location in the deep posterior compartment and adjacent to the soleus/gastrocnemius muscles that bulge with joint motion. Crush in the posterior tibial is greater for knee flexion and calf compression compared to ankle motion from a higher bone-to-muscle ratio near the ankle protecting against crush. Ostium-crossing stents experience larger shortening than those in individual arteries potentially because of a more oblique orientation. No significant stent bending was observed possibly because the midcalf is distant from knee and ankle joints and protected by the rigid tibia and fibula. These stent deformations can guide device development, interventional site selection, and indications for use.