KEY INCLUSION CRITERIA:

* at least 18 years old and considered skeletally mature
* diagnosed with degenerative joint disease (DJD) affecting the hindfoot due to a congenital or acquired deformity, osteoarthritis, rheumatoid arthritis, post- traumatic arthritis or ankylosing spondylitis of the ankle, subtalar, calcaneocuboid, and/or talonavicular joints
* requires one of the following hindfoot fusion proceduress with supplemental bone graft/substitute: ankle fusion (tibiotalar), subtalar fusion (talocalcaneal), calcaneocuboid fusion, talonavicular fusion, triple arthrodesis (subtalar, talonavicular and calcaneocuboid joints) OR double fusions (any combination of any two of the following: subtalar, talonavicular and calcaneocuboid joints)
* fusion site able to be rigidly stabilized with no more than 3 screws across the fusion site

* supplemental pins or staples allowed
* supplemental screws external to the fusion site(s) allowed
* signed informed consent document, independent, ambulatory, and can comply with all post-operative evaluations and visits

KEY EXCLUSION CRITERIA:

* undergone previous fusion surgery at the proposed location, i.e., revision of a failed fusion
* more than one previous procedure at the involved joints
* retained hardware spanning the joint(s) intended for fusion
* procedure anticipated to require plate fixation (including claw plates), IM nails or more than 3 screws to achieve rigid fixation based on pre-op planning
* procedure expected to require more than 9cc of graft material based on pre-op planning
* procedure expected to require structural bone graft, allograft, bone graft substitute, platelet rich plasma (PRP) or bone marrow aspirate
* procedure expected to require a pantalar fusion, i.e., fusion of ankle plus all hindfoot joints (talonavicular, subtalar, and calcaneocuboid) or an ankle fusion in combination with any hindfoot fusion
* radiographic evidence of bone cysts, segmental defects or growth plate fracture near the fusion site that could negatively impact the proposed fusion procedure
* tested positive or been treated for a malignancy in the past or is suspected of having a malignancy or currently undergoing radio- or chemotherapy treatment for a malignancy anywhere in the body, whether adjacent to or distant from the proposed surgical site
* pre-existing sensory impairment, e.g., diabetics with baseline sensory impairment, which limits ability to perform objective functional measurements and may be at risk for complications

- diabetics not sensitive to the 5.07 monofilament (Semmes-Weinstein) are to be excluded
* metabolic disorder known to adversely affect the skeleton other than primary osteoporosis or diabetes, e.g., renal osteodystrophy or hypercalcemia
* use of chronic medications known to affect the skeleton, e.g., glucocorticoid usage > 10mg/day
* pre-fracture neuromuscular or musculoskeletal deficiency which limits the ability to perform objective functional measurements
* physically or mentally compromised, e.g., current treatment for a psychiatric disorder, senile dementia, Alzheimer's disease, etc., to the extent that the Investigator judges the subject to be unable or unlikely to remain compliant
* allergic to yeast-derived products or bovine collagen or other bovine-sourced products
* received an investigational therapy within 30 days of proposed surgery or during the follow-up phase of the study
* is a prisoner, known or suspected transient or a history of drug/alcohol abuse within the 12 months prior to screening
* pregnant or intending to become pregnant within 12 months of the study procedure
* morbidly obese defined as BMI > 45 kg/m2
* currently has an acute infection at the surgical site