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Updated: Jun 6, 2025
Novel Diagnostics in Revision Arthroplasty: Implant Sonication and Multiplex Polymerase Chain Reaction
Published on: December 3, 2017
SPECT-CT may aid in determining which side of a revision stemmed implant problematic total knee replacement is loose
Daniel Hill1, Patrick Rogers1, Jonathan Phillips1
1Exeter Knee Reconstruction Unit, Princess Elizabeth Orthopaedic Unit, Royal Devon University Healthcare Foundation Trust, Barrack Road, Exeter EX2 5DW, United Kingdom.
Aim:
To evaluate SPECT-CT in the diagnosis of single component aseptic loosening in patients with a problematic cemented stemmed TKR (Total Knee Replacement).
Methods:
SPECT-CT was performed where aseptic loosening was suspected but was not clear on plain radiography. Demographics, suspected diagnosis and intention to revise were collected prospectively before and after SPECT-CT.
Results:
30 patients were investigated. 43% (95% CI: 0.5-0.9) had clear evidence of loosening on SPECT-CT. In 23% (95% CI: 0.1-0.4) intention to perform revision surgery following SPECT-CT changed (7/30) (p = 0.0004, standard error = 42.1, z = 3.5). Intentions to perform revision surgery according to the radiologist's overall summary were: Normal SPECT-CT - 0% (95% CI: 0.0-0.8) intention to revise (0/2). Possibly abnormal SPECT-CT - 13% (95% CI: 0.0-0.4) intention to revise (2/15). Definitely abnormal SPECT-CT - 77% (95% CI: 0.5-0.9) intention to revise (10/13). We report that SPECT-CT had a test sensitivity of 90.9% (95% CI: 0.6-1.0), a specificity of 100% (95% CI: 0.9-1.0), a positive predictive value of 100% and a negative predictive value of 97.7%. In 70% (95% CI: 0.3-0.9) of cases where revision surgery was performed for aseptic loosening SPECT-CT provided information that guided pre-operative planning with regards single component or both component revision surgery (7/10).
Conclusion:
When positive SPECT-CT was useful in determining single component revision. A normal SPECT-CT may have a negative predictive value; however, overall half of our series had a possibly abnormal or equivocal investigation.
