PliaFX Flo Subtalar Fusion Study

During a subtalar fusion, the bones making up the subtalar joint (talus and calcaneus) are permanently fused together. In the procedure, any damaged cartilage and bone at the subtalar joint is removed, then screws are inserted into the joint to fuse the bones together. Depending on the surgeon, a bone graft is sometimes applied between the bones prior to screw insertion to aid in bone bridging (growth of bone into the fusion site). Participants who consent to this study and are assigned to the PliaFX® Flo Allograft group, will receive PliaFX® Flo Allograft (human tissue donated from a donor) at the fusion site. The PliaFX® Flo system is demineralized bone fibers (hard minerals removed from bone using acid) in a sterile syringe that allows for delivery into small areas where bone graft is needed to assist bone fusion. The allograft bone fibers are produced from donated human cadaver (deceased human) bone. This study aims to determine whether the use of PliaFX® Flo Allograft in subtalar fusions will improve functioning and healing of the bone and cartilage for patients like you. Participants who are interested will discuss with their surgeon and be randomly assigned to one of the two study procedures below. The patient will not know what group they are in until after all data has been collected and all study visits are complete.

Inclusion Criteria: 1. The subject is at least 19 years of age. 2. The subject is considered to be skeletally mature. 3. The subject qualifies for subtalar fusion based on physical examination and/ or past medical history including isolated osteoarthritis, post-traumatic, degenerative, or rheumatoid arthritis of the ankle. 4. The subject experiences severe pain in the subtalar joint that could not be cured with non-operative treatment options. 5. The patient may undergo a subtalar fusion as part of a triple arthrodesis. 6. The patient may have forefoot pathology addressed by either prior or concurrent surgery (osteotomies or fusions). 7. The patient consented for either an arthroscopic or open procedure. 8. The subject is able to comply with all post-operative evaluations and visits. 9. The subject consents to and will receive either no graft or PliaFX® Flo allograft during their surgery Exclusion Criteria: 1. The subject has: * Severe osteoporosis * Neuromuscular impairment * Prior infection in the affected joint 2. The subject currently has acute infections that, in the opinion of the Investigator, may complicate healing. 3. The subject has a known or suspected allergy to any of the processing reagents listed in the packet insert (alcohol, glycinate buffer, and glycerol). 4. The subject is renal compromised. 5. The subject has a major risk factor for non-union (ex. poorly controlled diabetes or current smoker). 6. The subject is undergoing a revision of a prior subtalar fusion. 7. The subject has had a prior ankle joint fusion. 8. An ankle joint replacement or ankle joint fusion may be performed during the same sitting. 9. The subject has a BMI of \> 50 kg/m2. 10. The subject is known to be pregnant, or plans to become pregnant during the study period 11. The investigator judges the subject to be unable or unlikely to remain compliant to follow-up due to a physical or mental condition (ex. currently being treated for a psychiatric disorder, senile dementia, Alzheimer's disease, etc.). 12. The subject is unable to provide informed consent. 13. The subject is unable to communicate with the research team. 14. The subject is unable to comply with follow-up. 15. The subject has a history of substance addiction (e.g. recreational drugs, narcotics, or alcohol) within 12 months prior to screening for study entry 16. The subject will be receiving a structural autograft or allograft (such as a femoral head graft or tri cortical iliac crest graft) to fill a defect greater than 1cm3