Single-photon-emission computed tomography in painful total ankle replacements

Area of Science:

• Orthopedic surgery
• Radiology
• Nuclear medicine

Background:

• Unexplained foot and ankle pain can be challenging to diagnose, especially after total ankle replacement (TAR).
• Conventional imaging modalities may fail to identify the cause of pain in painful TARs.
• SPECT-CT imaging offers a potential solution for investigating such complex cases.

Purpose of the Study:

• To evaluate the utility of SPECT-CT imaging in diagnosing the causes of pain in patients with total ankle replacements.
• To determine if SPECT-CT can identify implant loosening or other issues not visible on standard radiographs.

Main Methods:

• A retrospective analysis of 14 patients who underwent SPECT-CT for painful TARs between 2010 and 2014.
• Patients had a minimum of 18 months between surgery and imaging.
• Infection was excluded via joint aspiration when clinically indicated.

Main Results:

• SPECT-CT identified increased osteoblastic activity, indicative of implant loosening, in 13 out of 14 patients.
• Talar component loosening was the most common finding (13 cases), with tibial component involvement in 5 cases.
• In 10 cases, loosening was not evident on plain radiographs, highlighting the limitations of conventional imaging.

Conclusions:

• SPECT-CT imaging demonstrates a high incidence of talar prosthesis nonintegration in painful total ankle replacements.
• This advanced imaging technique is crucial for diagnosing loosening when plain radiographs are inconclusive.
• A high suspicion for talar prosthesis nonintegration is warranted in patients with persistent medial ankle pain post-TAR.