Published Resources

Extraosseous Talotarsal Stabilization Using HyProCure® in Adults: A 5-year Retrospective Follow-up
Authors: Graham, Michael E. Jawrani, Nikhil T. Chikka, Avanthi. The Journal of Foot and Ankle Surgery 51(1) 23-29
    Abstract: The purpose of this retrospective study was to determine long-term functional outcomes and device tolerance achieved in adult patients who chose to undergo an extraosseous talotarsal stabilization procedure HyProCure® for the treatment of flexible talotarsal joint deformity. Eighty-three adult patients participated in this study. Postoperative subjective assessment of device performance was evaluated using Maryland Foot Scores, which were collected at a mean follow-up period of 51 months. The mean postoperative Maryland Foot Score was 88 out of 100; postoperatively, 52% of cases reported complete alleviation of foot pain, 69% of cases had no limitations on their foot functional abilities, and 80% of cases reported complete satisfaction with the appearance of their feet. The implant was removed in 7 out of 117 cases (removal rate: 6%) due to prolonged pain of the anterior talofibular ligament (4 cases), psychogenic reaction (2 cases), and postoperative infection (1 case). The long-term positive subjective outcomes and excellent patient satisfaction obtained in this study may imply that extraosseous talotarsal stabilization was effective in stabilizing the talotarsal joint complex and eliminating excessive abnormal pronation, thus reducing pain and improving quality of life of the patients; it represents a possible treatment option for partial talotarsal dislocation in cases with flexible and reducible deformity.
The Effect of HyProCure® Sinus Tarsi Stent on Tarsal Tunnel Compartment Pressures in Hyperpronating Feet. Authors: Graham, Michael E. Jawrani, Nikhil T. Vijay K. Goel,. The Journal of Foot and Ankle Surgery 51(1) 44-49
    Abstract: Tarsal tunnel syndrome is characterized by increased pressure in the tarsal tunnel. In hyperpronation, there is excessive abnormal pronation resulting from partial displacement of the talus on the calcaneus. In this study, we hypothesized that hyperpronation caused by talotarsal instability will lead to increased pressure in the tarsal tunnel and porta pedis. We also hypothesized that the pressure in these compartments will decrease following an extra-osseous talotarsal stabilization procedure using HyProCure®. Pressures in the tarsal tunnel and porta pedis were measured in 9 fresh-frozen cadaver specimens using an intracompartmental pressure monitor system. Pressures were measured with the foot in neutral and hyperpronated position, before and after stabilization using HyProCure. For the tarsal tunnel, pressure in the neutral position with and without HyProCure was 3 ± 3 mm Hg and 4 ± 3 mm Hg, respectively (P = .159). However, for the hyperpronating foot, the pressure decreased from 32 ± 16 mm Hg to 21 ± 10 mm Hg (P < .001) following the placement of HyProCure. In the porta pedis, pressure in the neutral position with and without HyProCure was 2 ± 2 mm Hg and 2 ± 2 mm Hg, respectively (P = .168). However, for the hyperpronating foot, the pressure decreased from 29 ± 15 mm Hg to 18 ± 11 mm Hg (P < .001) following the placement of HyProCure. The pain caused by compression of the posterior tibial nerve in the tarsal tunnel and its branches in the porta pedis, owing to hyperpronation, may be alleviated by implantation of HyProCure.
Stabilization of Joint Forces of the Subtalar Complex via HyProCure Sinus Tarsi Stent. Michael E. Graham, DPM*, Rachit Parikh, MS*, Vijay Goel, PhD†, Devdatt Mhatre, MS†, and Aaron Matyas, MS†. The Journal of American Podiatric Medical Association. Sept2011 101(5):390-399
    Background: The foot is the foundation of the body. The stability of the osseous hindfoot structure is crucial in bipedal locomotion. The subtalar joint is responsible for conversion of the rotatory forces of the lower extremities and dictates the movements of the midtarsal joints and the forefoot. In a hyperpronated foot, excessive abnormal pronation results in partial to full obliteration of the sinus tarsi. The hypothesis is that the HyProCure device will prevent obliteration of the sinus tarsi, thereby stabilizing the subtalar joint complex and eliminating the excessive forces to the proximal and distal musculoskeletal system that occur with every step.Methods: Five fresh-frozen human foot cadaver specimens that represented pathologic hindfoot and midfoot instability and partial to full obliteration of the sinus tarsi were axially compressed to 2,000 N and internally rotated by 15° to produce maximum pronation of the subtalar joint using a biaxial materials testing machine. The forces were measured across the posterior and anterior talocalcaneal joint facets before and after placement of the HyProCure stent. Results: The subtalar joint stabilized after placement of the HyProCure sinus tarsi stent. The mean ± 1 SD forces in the posterior talocalcaneal joint increased from 795.88 ± 106 N to 1,004.86 ± 72.41 N (P < 0.05, two-tailed paired t test). The mean ± SD forces at the anterior talocalcaneal joint decreased from 520.15 ± 127.18 N to 394.56 ± 73.83 N (P < 0.05), shifting the contact area posteriorly.Conclusions: Placement of the HyProCure subtalar stabilization stent in a hyperpronated foot prevents excessive talar subluxation and assists in proper distribution of the axial loads on the subtalar facet joints.
Evaluating Plantar Fascia Strain in Hyperpronating Cadaveric Feet Following an Extra-osseous Talotarsal Stabilization Procedure. Authors: Graham, Michael E. Jawrani, Nikhil T. Vijay K. Goel,. The Journal of Foot and Ankle Surgery 50(6) 682-686
    Abstract: Abnormal talotarsal joint mechanics leading to hyperpronation is implicated as one of the most common causes of plantar fasciopathy. In patients with hyperpronating feet, the plantar fascia experiences excessive tensile forces during static and dynamic weight-bearing activities because of excessive medial longitudinal arch depression. For the purposes of this study, we hypothesized that plantar fascia strain in hyperpronating cadaveric feet would decrease after intervention with an extra-osseous talotarsal stabilization (EOTTS) device. A miniature differential variable reluctance transducer was used to quantify the plantar fascia strain in 6 fresh-frozen cadaver foot specimens exhibiting flexible instability of the talotarsal joint complex (i.e., hyperpronation). The strain was measured as the foot was moved from its neutral to maximally pronated position, before and after intervention using the HyProCure® EOTTS device. The mean plantar fascia elongation was 0.83 ± 0.27 mm (strain 3.62% ± 1.17%) and 0.56 ± 0.2 mm (strain 2.42% ± 0.88%) before and after intervention, respectively (N = 18, variation reported is ± 1 SD). The average plantar fascia strain decreased by 33%, and the difference was statistically significant with p < .001. From this cadaveric experiment, the reduction in plantar fascia strain suggests that an EOTTS device might be effective in stabilizing the pathologic talotarsal joint complex and the medial longitudinal arch and in eliminating hyperpronation. An EOTTS procedure might offer a possible treatment option for plantar fasciopathy in cases in which the underlying etiology is abnormal talotarsal biomechanics.
Effect of Extra-osseous Talotarsal Stabilization on Posterior Tibial Tendon Strain in Hyperpronating Feet. Authors: Graham, Michael E. Jawrani, Nikhil T. Vijay K. Goel,. The Journal of Foot and Ankle Surgery 50(6) 676-681
    Abstract: Posterior tibial tendon dysfunction is considered one of the most common causes of progressive adult acquired flatfoot deformity. The etiology leading to the dysfunction of posterior tibial tendon remains controversial. The purpose of this study was to quantify strain on the posterior tibial tendon in cadaver feet exhibiting hyperpronation caused by flexible instability of the talotarsal joint complex. We hypothesized that posterior tibial tendon strain would decrease after a minimally invasive extra-osseous talotarsal stabilization procedure. A miniature differential variable reluctance transducer was used to measure the elongation of posterior tibial tendon in 9 fresh-frozen cadaver specimens. The elongation was measured as the foot was moved from its neutral to maximally pronated position, before and after intervention with the HyProCure® extra-osseous talotarsal stabilization device. The mean elongation of the posterior tibial tendon (with respect to a fixed reference point) was found to be 6.23 ± 2.07 mm and 3.04 ± 1.85 mm, before and after intervention, respectively (N = 27; variation is ± 1 SD). The average elongation reduced by 51% and was statistically significant with p < .001. Strain on the posterior tibial tendon is significantly higher in hyperpronating feet. An extra-osseous talotarsal stabilization procedure reduces excessive abnormal elongation of the posterior tibial tendon by minimizing excessive abnormal pronation. This minimally invasive procedure may thus provide a possible treatment option to prevent or cure posterior tibial tendon dysfunction in patients exhibiting flexible instability of the talotarsal joint complex.
Radiographic Evaluation of Navicular Position in the Sagittal Plane—Correction Following an Extraosseous Talotarsal Stabilization Procedure Authors: Graham, Michael E. Jawrani, Nikhil T. Chikka, Avanthi. The Journal of Foot and Ankle Surgery 50(5) 551-557
    Abstract:The navicular drop in the sagittal plane on weight-bearing is a valid indicator of foot pronation. Dislocation of the talus on the tarsal mechanism results in hyperpronation, which can lead to excessive navicular drop. The purpose of the present study was to radiographically determine the efficacy of HyProCure® in realigning the navicular bone in hyperpronating feet. We hypothesized that following the placement of HyProCure®, the navicular height would increase significantly compared to its preoperative value. Radiographs of 61 adult patients (86 feet) who received HyProCure® without adjunctive hindfoot or midfoot soft tissue or osseous procedures were analyzed. The distance of the navicular with respect to the cuboid was measured from the pre- and postoperative weight-bearing lateral radiographs. Additionally, we measured foot length to normalize the navicular to cuboid distance. The postoperative radiographs were taken at an average follow-up of 17 days. The mean preoperative true navicular to cuboid distance was 19 ± 6 mm as compared to a mean postoperative value of 24 ± 5 mm. The mean pre- and postoperative normalized navicular to cuboid distances were 0.098 ± 0.029 and 0.125 ± 0.027, respectively (± 1 SD). The postoperative increase in the true and normalized navicular to cuboid distance was statistically significant (p < .001). HyProCure® was effective in improving the anatomic alignment of the talonavicular joint by reducing excessive navicular drop. This indicates reduction of excessive abnormal pronation and stabilization of the medial column of the foot, which can also lead to reduction in the excessive forces placed on the supporting soft tissue structures.

Recent Posts