The Use of a Dynamic Sustained Compression Intramedullary Nail for Tibiotalocalcaneal Arthrodesis

The purpose of this study is to determine the clinical efficacy of a novel sustained dynamic compression intramedullary nail for tibiotalocalcaneal (TTC) arthrodesis utilizing longitudinal weight-bearing computed tomographic imaging. Of particular focus will be assessment of compressive element recovery and its relation to fusion development over time and weight-bearing status. Additionally, the study will incorporate longitudinal fusion assessment to evaluate differences between three-dimensional weight-bearing computed tomography (WBCT) scans and two-dimensional radiographs (X-rays) at multiple points of the fusion process. Finally, the study will evaluate the differences in WBCT-based fusion assessment between automated and manual methodologies for fusion area calculation.

This study is a collaborative effort between the Orthopedic Foot and Ankle Center, MedShape, Inc, and CurveBeam. This is a prospective investigation to assess the clinical outcomes of patients with a tibiotalocalcaneal arthrodesis with the Sustained Dynamic Compression Intramedullary Nail (DynaNail), including longitudinal assessment with weight-bearing CT. The investigators plan to enroll 45 patients. No placebo control will be used, as there is no other IM nail available capable of providing sustained compression. Additionally, given that many patients receiving this treatment have had prior failed treatments and face poor alternatives such as amputation, using a prior-generation IM nail as a control treatment would be unethical.

Design:

This is a prospective, single-group study. Patients of the Orthopedic Foot and Ankle Center who are scheduled to undergo TTC arthrodesis will be screened for eligibility and informed consent will be obtained from those who meet the inclusion/exclusion criteria. Subjects will be assessed pre-operatively and then at five post-operative intervals: 1 week, 6 weeks, 3 months, 6 months, and 12 months. A WBCT scan will be obtained at each interval.

Selection of Subjects:

Patients will be identified in the clinic by an attending orthopaedic foot and ankle surgeon or his/her 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 and co-investigator.

Pre-operative Questionnaire:

After informed consent, the patients will be asked to complete patient reported outcomes questionnaires that are part of the SOS Registry associated with function and pain, including VAS, VR-12, FFI-R, FAAM, AOS, and AOFAS. The patients will also be asked to provide information related to prior medical history (including potential co-morbidities associated with non-union, i.e. tobacco usage, neuropathy, renal disease, obesity, etc.) and surgical history of the subject lower extremity.

Surgery:

The following surgical procedure is standard of care. The surgical procedure will involve both tibiotalar and talocalcaneal joint preparation through any approach (lateral, posterior, anterior with sinus tarsi). The use of supplemental bone graft is at the discretion of the treating surgeon but must be documented. The MedShape DynaNail 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 initially. The patient will be discharged from the hospital when medically ready. Weight-bearing will start at seven weeks post-surgery.

Follow-Up Visits and Questionnaires:

The patient will return to clinic for visits at the following intervals after surgery: 1 week, 6 weeks, 3 months, 6 months, and 12 months. At each of these time points, a clinical exam will be conducted, and SOS patient questionnaires will be administered, as well as a radiographic and clinical follow-up form. Additionally, radiograph and weight-bearing CT imaging will be obtained of both the ankle and subtalar joints. At 3 months and 12 months post-op, all X-ray and CT images will be de-identified, burned to a DVD, and copies will be sent to both co-sponsors.

Eligibility Criteria:
Inclusion Criteria:

* Meets indications for TTC arthrodesis and receives the DynaNail implant
* Able to understand the requirements of the study
* Willing to comply with the study protocol
* Sign an Informed consent
* 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