Correlations of typical pain patterns with SPECT/CT findings in unhappy patients after total knee arthroplasty

Abstract

Purpose The diagnostic process in patients after painful total knee arthroplasty (TKA) is challenging. The more clinical and radiological information about a patient with pain after TKA is included in the assessment, the more reliable and sustainable the advice regarding TKA revision can be. The primary aim was to investigate the position of TKA components and evaluate bone tracer uptake (BTU) using pre-revision SPECT/CT and correlate these findings with previously published pain patterns in painful patients after TKA. Methods A prospectively collected cohort of 83 painful primary TKA patients was retrospectively evaluated. All patients followed a standardized diagnostic algorithm including 99m-Tc-HDP-SPECT/CT, which led to a diagnosis indicating revision surgery. Pain character, location, dynamics and radiation were systematically assessed as well as TKA component position in 3D-CT. BTU was anatomically localized and quantified using a validated localization scheme. Component positioning and BTU were correlated with pain characteristics using non-parametric Spearman correlations (p < 0.05). Results Based on Spearman’s rho, significant correlations were found between pain and patients characteristics and SPECT/CT findings resulting in nine specific patterns. The most outstanding ones include: Pattern 1: More flexion in the femoral component correlated with tender/splitting pain and patella-related pathologies. Pattern 3: More varus in the femoral component correlated with dull/heavy and tingling/stinging pain during descending stairs, unloading and long sitting in patients with high BMI and unresurfaced patella. Pattern 6: More posterior slope in the tibial component correlated with constant pain. Conclusion The results of this study help to place component positioning in the overall context of the "painful knee arthroplasty" including specific pain patterns. The findings further differentiate the clinical picture of a painful TKA. Knowing these patterns enables a prediction of the cause of the pain to be made as early as possible in the diagnostic process before the state of pain becomes chronic. Level of evidence Level III

The role of SPECT/CT in painful, noninfected knees after knee arthroplasty: a systematic review and meta-analysis—a diagnostic test accuracy review

“…The use of this image scheme was also important for defining particular BTU patterns associated with specific conditions, such as malpositioning of the components, maltracking, patellar overloading, patellar osteoarthritis and loosening, which led the clinician to change the initial diagnosis in up to 85% of the patients [ 40 , 41 , 46 ]. It is important to highlight a recent report by Mathis et al [ 21 ], which showed a significant correlation ( P < 0.05) between different patterns of BTU and the position of the TKA components together with different pain patterns, enhancing the importance of the component position as a potential source of pain in painful knee arthroplasty patients. The authors concluded that component positioning-related pathologies accounted for the greatest proportion of cases, followed by patella-related problems and instability.…”

“…The highest diagnostic accuracy for SPECT/CT in detecting loosening was reported by Abele et al and Bao et al [ 39 , 42 ], who used intraarticular administration of the radiotracer 99m Tc sulphur colloid with a sensitivity and negative predictive value of 100%, which was superior to other imaging methods. SPECT/CT was also able to identify other sources of pain, such as patellofemoral hyper pressure, instability and malalignment of the components, with findings confirmed by intraoperative or clinical follow-up [ 21 , 47 ].…”

“…Published evidence on the application of SPECT/CT in the diagnostic approach to painful knees after knee arthroplasty, although scarce, has increased in recent years, and the utility of SPECT/CT has been demonstrated in different scenarios where conventional imaging tools have limitations [ 20 ]. In a recent publication using SPECT/CT in patients with painful knees after knee arthroplasty, the authors demonstrated how component positioning-related pathologies accounted for the greatest proportion, followed by patella-related problems and instability, in contrast to much of the data published in recent years; they also reported a correlation between total knee arthroplasty (TKA) component positioning and pain and argued that in SPECT images, an increase in bone tracer uptake (BTU) in femoral areas and areas around the tibial stem or tip was more specific for the identification of a pathological condition in patients with painful TKA [ 21 ]. As an added condition, technological improvements in CT and nuclear medicine devices have led to higher-resolution images, permitting better qualitative and quantitative analysis of BTU with superior anatomical correlation.…”

Preoperative patellar bone marrow lesions with full thickness cartilage defects correlate with residual anterior knee pain in total knee arthroplasty without patellar resurfacing

“…Several studies have found the increased bone tracer uptake (BTU) in single‐photon emission computed tomography/computed tomography (SPECT/CT) could be a valuable method for predicting residual pain following TKA [2, 31]. Furthermore, Mathis et al [20] demonstrated a significant correlation between the areas of increased BTU and pain patterns after TKA. Additionally, Slevin et al [34] suggested that SPECT/CT could be a valuable modality for diagnosing patellofemoral disorders after TKA.…”

Under-correction of preoperative varus alignment does not lead to a difference in in-vivo bone loading in 3D-SPECT/CT compared to neutral alignment

“…An increase of BTU in femoral or tibial regions could indicate signs of aseptic loosening or infection. [25,35,[51][52][53][54][55][56] Thirdly, there were no significant BTU differences between the alignment groups after TKA. This could be explained as follows.…”