Abstract
BackgroundA comparative analysis of the strengths and weaknesses of three different methods for radiologic evaluation of patellofemoral instability (PFI).MethodsComputed tomography (CT) and magnetic resonance imaging (MRI) were performed in 47 patients with or without PFI. The tibial tubercle-trochlear groove (TT-TG) distance was measured by two observers through conventional CT and three-dimensional CT reconstruction (TDR-TT-TG) respectively and the tibial tubercle-posterior cruciate ligament (TT-PCL) distance with MRI. The intraclass correlation coefficient (ICC) was used to evaluate the interobserver reliability. In addition, the differences of three measurements between different patients were compared. The consistency of TT-TG and TDR-TT-TG was analyzed by the Bland-Altman method.ResultsThe ICCs of three measurements were high between two observers; the results were TT-TG (ICC = 0.852), TDR-TT-TG (ICC = 0.864), and TT-PCL (ICC = 0.758). The values of PFI patients were significantly higher than those of non-PFI patients, and the mean TT-TG, TDR-TT-TG, and TT-PCL distance in patients with PFI were 19.0 ± 3.8 mm, 19.0 ± 3.7 mm, and 25.1 ± 3.6 mm, respectively. There was no statistically significant difference between the TT-TG distance and the TDR-TT-TG distance, we found no significant difference. The Bland-Altman analysis showed that the TDR-TT-TG distance was in good agreement with the TT-TG distance.ConclusionAll three methods can be used to assess PFI; the TDR-TT-TG measurement method has superior operability and better interobserver consistency. It may be an alternative method to the conventional TT-TG distance measurement.
Highlights
Patellofemoral instability (PFI) refers to the fact that the patella cannot slide normally in the femoral trochlear groove, causing one or more subluxations or dislocations and abnormal patella slippage, resulting in a series of symptoms [1]
Basic characteristics of the included patients The patellofemoral instability (PFI) group included 19 males and 28 females, aged 11–49 years old, with an average age of 20.7 ± 8.0 years; in the control group, 33 males and 14 females were included in the analysis, aged 23–56 years old, with a mean age of 31.8 ± 12.7 years old
The three measurements had good agreement among the different observers (ICC values > 0.75), and the three-dimensional CT reconstruction (TDR)-tubercle-trochlear groove (TT-TG) measurement has the best interobserver consistency (ICC = 0.864), which illustrates that the reliability of the three methods is superior
Summary
Patellofemoral instability (PFI) refers to the fact that the patella cannot slide normally in the femoral trochlear groove, causing one or more subluxations or dislocations and abnormal patella slippage, resulting in a series of symptoms [1]. The reversed dynamic patellar apprehension test was recently introduced by Zimmermann et al [10] as a reliable clinical examination tool for the diagnosis of PFI, but its clinical use still needs more research confirmation. The diagnosis of PFI still mainly relies on the comprehensive judgment of combining the patients’ medical history with a detailed physical examination and imaging procedures. A comparative analysis of the strengths and weaknesses of three different methods for radiologic evaluation of patellofemoral instability (PFI)
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