gms | German Medical Science

Objectives: Aseptic loosening is amongst the most common causes of a painful total hip arthroplasty (THA) yet it can be challenging to validate this diagnosis. 3-phase bone scintigraphy (TPBS) has been suggested to improve detection of component loosening, but its diagnostic value remains controversial. Diagnostic accuracy may be further impaired in cases with periprosthetic joint infection (PJI). The current study aims to answer the following research questions:

1.

What is the diagnostic accuracy of TPBS in predicting component loosening in THA?

2.

Does the presence of PJI impair the predictive value of TPBS?

Methods: This is a retrospective study on 146 consecutive cases that underwent TPBS prior to THA revision surgery between 2012 and 2019 at the authors’ institution. TPBS was conducted with technetium 99m-hydroxydiphosphonate. The scans were evaluated by a senior radiologist regarding the presence of 1) increased uptake and 2) component loosening. PJI was defined according to the MSIS criteria. Component loosening was defined intraoperatively. Intraoperative and TPBS results were compared to obtain the diagnostic value of TPBS to predict component loosening. Descriptive statistics were performed to describe means, ranges, and standard deviations for all variables. Specificity and sensitivity were calculated with Cross tables, correlations were calculated with two-sided Pearsons-Score.

Results and conclusion: The study cohort comprised 36 THA (24.7%) with PJI and 110 THA (75.3%) undergoing aseptic revisions. Overall, “Loosening” in TPBS showed a sensitivity of 55.8% and specificity of 57.7% compared to intraoperative findings. When both conditions, “increased uptake” and “loosening”, were combined and compared to intraoperative findings, sensitivity for detecting a loose implant increased to 85.0%, specificity decreased to 38.5%. In presence of PJI, the specificity of “loosening” in TPBS was only 25%. When TPBS was negative for both, “loosening” and “increased uptake”, still 60% of the THA were loose intraoperatively. These values were similar for aseptic revisions with 78% and 65%, respectively.

Assessment of component loosening with TPBS showed weak agreement with intraoperative findings in both septic and aseptic THA revisions. The diagnostic accountability of TPBS further decreased in presence of PJI. In respect of the limited diagnostic accuracy, TPBS is not advisable as a routine tool in the differential diagnosis of component loosening prior to THA revision surgery.