The purpose of this study is to determine the clinical efficacy of a novel dynamic sustained compression intramedullary nail for subtalar (talocalcaneal) arthrodesis.

This proposal is a collaborative effort between MedShape and the University of California, Davis Medical Center. This is a prospective investigation to assess the clinical outcomes of patients with a subtalar arthrodesis with the Sustained Dynamic Compression Intramedullary Nail (DynaNail Mini). The study plan is to enroll 60 patients.

Patients with end-stage talocalcaneal (subtalar) joint arthritis from any etiology will be asked to enroll in the study. After informed consent, the patients will be asked to complete the following patient reported outcomes questionnaires as part of the Surgical Outcomes System (SOS) Global Registry: Visual Analog Scale (VAS) for pain, Veterans RAND 12 Item Health Survey for function, Foot Function Index - Revised for function and pain, the Foot and Ankle Ability Measure (FAAM) for function, and the American Orthopaedic Foot and Ankle Society (AOFAS) scales for pain, function, and alignment. After informed consent, they will then be scheduled for surgery in a routine fashion.

The following surgical procedure is standard of care. The surgical procedure will involve subtalar (talocalcaneal) joint preparation through a lateral approach. The use of supplemental bone graft is at the discretion of the treating surgeon but must be documented. The MedShape DynaNail Mini will then be inserted according to the manufacturer's technique. The patient will be placed in a short leg splint and kept non-weight bearing. The patient will be discharged from the hospital when medically ready.

The patient will return to clinic for visits at the following intervals after surgery: 6 (+/- 1) weeks, 14 (+/- 1) weeks, 6 months (+/- 2 weeks), and 12 months (+/- 2 weeks). At each of these time points, the same SOS patient specific outcome questionnaires will be administered. 3-view X-rays will be taken at each of these visits to assess the amount of travel of the Mini compressive element. At 15 (+/- 1) weeks post-op, a CT scan will be obtained to assess healing. Additionally, a radiographic and clinical follow-up form will be filled out at each of the following follow-up visits: 6 weeks, 14 weeks, 6 months, and 1 year.

Patients will be identified in the clinic by an attending orthopaedic foot and ankle surgeon or his physician assistant based on clinical exam and radiographic findings. Inclusion criteria include anyone over age 18 who has end-stage subtalar arthritis and has failed nonoperative management. Typically, these patients have multiple medical comorbidities and therefore the exclusion criteria will be patients who are not healthy enough to undergo surgery. Additional exclusion criteria include non-English speakers, and patients that are blind, illiterate, or are prisoners. Additionally, pregnant women will be excluded. Patients of all racial, religious, and cultural backgrounds will be included in this study.

Inclusion Criteria:

• End-stage talocalcaneal (subtalar) joint arthritis from any etiology will be eligible to enroll in the study
• Meets indications for subtalar arthrodesis to receive the DynaNail Mini implant
• Able to understand the requirements of the study, provide a written consent, and willing to comply with the study protocol
• 18 years of age or older

Exclusion Criteria:

• Investigator determines that the subject is unlikely to comply with the requirements of the study
• Non-English speaker
• Blind
• Illiterate
• Prisoner
• Pregnant women

Patients will be identified in the clinic by an attending orthopaedic foot and ankle surgeon or his physician assistant based on clinical exam and radiographic findings. Patients will be screened for eligibility by the research coordinator/ key personnel in close coordination with the surgeon.

Patients at institute with end-stage talocalcaneal (subtalar) joint arthritis from any etiology will be eligible to enroll in the study. Frequently, subtalar arthritis is caused by trauma. Traumatic injuries have no predilection for race, religion, cultural background, etc. Therefore, all demographic groups will have access to this study and should be represented. Approximately 60 patients will be recruited for the study.