Abstract
Introduction
SPECT/CT might be a promising diagnostic modality in patients with painful total knee arthroplasty. It was the purpose of our study to introduce a novel standardised SPECT/CT algorithm for assessing patients with painful primary total knee arthroplasty and to evaluate its clinical applicability and inter- and intra-observer variation and reliability.
Methods
A novel SPECT/CT localisation scheme, which consists of 9 tibial, 9 femoral and 4 patellar regions on standardised transverse, coronal, and sagittal slices was introduced. It was assessed in 18 consecutive patients with painful knees after total knee arthroplasty. The localisation and level of the tracer uptake on SPECT/CT were noted using a color coded 10 steps graded scale (0-100). The inter and intra-observer reliability were assessed. The femoral and tibial prosthetic component position was assessed in the CT images after 3D reconstruction and aligning them to standardised frames of reference. The average root mean square difference±standard deviations and ranges of these measured angles are presented along with the intraclass correlation coefficients for inter- and intraobserver reliability.
Results
The localisation scheme was useful and easily applicable in all 18 cases. The novel classification using the SPECT/CT for the femoral, the tibial and patellar region was reliable. The measurements of component position in SPECT/CT images were highly reliable and feasible in all cases with sufficient visibility of the landmarks. The mean intra-observer difference between the rotational alignment measurements of tibial and femoral components was less than 2° (2SD 1°). The intra-observer variability for these measurements was less than 1 degree (2SD 1°).
Conclusions
The introduced algorithm using SPECT/CT in patients after total knee arthroplasty, which combines mechanical (assessment of 3D rotational alignment of the prosthesis in the inherent CT data) and metabolic data (SPECT/CT localisation scheme), was highly reliable and useful. We propose its use in larger scaled clinical studies to investigate its clinical value.
