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Category: Hindfoot; Ankle Introduction/Purpose: Magnetic resonance anatomy of the hindfoot as seen at the level of the sustentaculum tali is intricate due to surrounding muscles, tendons, aponeurosis and ligaments. The objective of this work is to provide a mnemonic with illustrative figures to simplify this complex anatomical region on coronal T1-weighted magnetic resonance images (T1-MRIs). Methods: One hundred and twenty-four patients referred for foot and ankle complaints were scanned utilizing standard MRI imaging protocols for evaluation of the hindfoot. Only coronal T1-MRIs of the calcaneus at the level of sustentaculum tali of unremarkably reported patients were selected for the development of this mnemonic. T1- and T2-MRIs of an additional set of patients with hindfoot pathologies were selected to demonstrate how this mnemonic is adapted to identify specific pathologies. Results: Upon viewing the calcaneus with the adjacent anatomical structures on coronal T1-MRIs, the overall appearance resembles a ''Hen in the Nest with Four Eggs.'' The calcaneus represents the body of the hen, while the sustentaculum tali forms the head and neck. The posterior tibial tendon represents the crest of the hen, and the flexor digitorum longus and flexor hallucis longus tendons represent its beak and wattle, respectively. The peroneus brevis and peroneus longus tendons represent the tail, and the long plantar ligament represents the flexed legs of Haleem's hen. The plantar aponeurosis represents the hen's nest. Whereas the abductor hallucis, flexor digitorum brevis, abductor digiti minimi and quadratus plantae muscles are the four eggs. Pes planus, flexor digitorum brevis hemangioma, Baxter's neuropathy associated with chronic denervation abductor digiti minimi atrophy and peroneal tendonitis are some of the hindfoot pathologies that can be identified utilizing the mnemonic. Conclusion: The mnemonic, 'Haleem's Hen in the Nest with Four Eggs,' serves as a simplified phrase for orthopedic surgeons, radiologists and other physicians to easily recall the anatomy of the hindfoot when viewing it at the level of the sustentaculum tali on coronal T1-MRIs. In addition, this mnemonic could be particularly useful when utilized in medical education curriculum for residents, fellows, and medical students. Further research is required to validate this mnemonic as an educational tool in medical training and detail additional hindfoot pathologies that can be identified with it.

Magnetic resonance anatomy of the hindfoot as seen at the level of the sustentaculum tali is intricate due to surrounding muscles, tendons, aponeurosis and ligaments. The objective of this work is to provide a mnemonic with illustrative figures to simplify this complex anatomical region on coronal T1-weighted MR images (T1-MRIs).One hundred and twenty-four patients referred for foot and ankle complaints were scanned utilizing standard MRI imaging protocols for depiction of the hindfoot. Only coronal T1-MRIs of the calcaneus at the level of sustentaculum tali of unremarkably reported patients were selected for this work.Upon viewing the calcaneus with the adjacent anatomical structures on coronal T1-MRIs, the overall appearance resembles a "Hen in the Nest with Four Eggs''. The calcaneus represents the body of the hen, while the sustentaculum tali forms the head and neck. The posterior tibial tendon represents the crest of the hen, and the flexor digitorum longus and flexor hallucis longus tendons represent its beak and wattle, respectively. The peroneus brevis and peroneus longus tendons represent the tail, and the long plantar ligament represents the flexed legs of Haleem's hen. The plantar aponeurosis represents the hen's nest. Whereas the abductor hallucis, flexor digitorum brevis, abductor digiti minimi and quadratus plantae muscles are the four eggs.The mnemonic, "Haleem's Hen in the Nest with Four Eggs", serves as a simplified phrase for radiologists and orthopedic surgeons to easily recall the anatomy of the hindfoot when viewing it at the level of the sustentaculum tali on coronal T1-MRIs.

Category: Ankle Arthritis; Hindfoot Introduction/Purpose: Subtalar arthrodesis is a frequently performed surgery used to treat several hindfoot pathologies. Rigid fixation is essential for successful fusion and percutaneous screws are most commonly used. Controversy still exists regarding the most optimal screw configuration. While cadaveric biomechanical studies have shown diverging screw configuration to be superior to parallel screws, this has never been proven in the clinical setting. The aim of this study was to compare fusion rates and clinical outcomes between patients treated with divergent versus parallel screw constructs for subtalar arthrodesis. Methods: We conducted a retrospective review of 58 patients that underwent subtalar arthrodesis during a four-year period at our institutions. Patients were divided into two groups based on screw construct; diverging versus parallel. Outcomes measured were radiographic and clinical evidence of fusion at 3 months, American Orthopaedic Foot & Ankle (AOFAS) ankle-hindfoot and Visual Analog Scale (VAS) scores at final follow up and post-operative complications. Results: Thirty patients underwent subtalar fusion with a divergent screw construct and twenty-four with parallel screws. The mean age was 58.5+-13.9 years and mean follow up period was 44.5+-20.8 months. The overall fusion rate at 3 months was 94.8%. The fusion rate for the divergent screw group was 93.3% versus 96.4% for the parallel screw group, showing no statistical significance (p=0.60). Overall, the mean AOFAS and VAS scores improved post-operatively by 28.1+-5.49 and 4.27+-1.45 points respectively (p<.0001). In the divergent group, mean improvement in AOFAS and VAS scores was 28.5+- 4.99 and 4.39+-1.42 versus 27.7+-6.05 and 4.14+-1.48 in the parallel screw group, showing no statistical significance (p=0.59 and p=0.44). The overall complication rate was 5.2% with no statistically significant difference between the two groups (6.7% versus 3.6%, p=0.60). Conclusion: When used for fixation during subtalar arthrodesis, divergent and parallel screw constructs have similar radiological union rates and clinical outcomes when it comes to fusion rates at 3 months, post-operative improvement in AOFAS scores and complication rates. Screw configuration should be determined by surgeon experience and comfort level.