Imaging Characteristics of Contralateral Asymptomatic Patellofemoral Joints in Patients with Unilateral Instability

Abstract

).q RSNA, 2014 Purpose:To test the hypothesis that in patients with unilateral patellofemoral instability (PI), the contralateral asymptomatic joints have abnormal morphology and imaging features of osteoarthritis (OA) at four-dimensional (4D) computed tomography (CT). Materials and Methods:The institutional review board approved this HIPAA-compliant retrospective study. Informed consent was waived. Radiology records were reviewed to identify 25 patients (male-female ratio, 0.56; median age, 20 years; range, 13-43 years) with unilateral PI undergoing 4D CT and 25 age-and sex-matched control patients undergoing multidetector CT. Trochlear groove depth (TGD), tibial tuberosity-trochlear groove (TT-TG) distance, and patellar height ratio (PHR) were determined to compare morphology, and bisect offset (BO) measurements were obtained to compare lateral displacement of the patella between the two groups by using the Wilcoxon rank-sum test. All images were interpreted by trained observers. Tracking patterns of the patellae were determined by obtaining BO measurements at various flexion angles with 4D CT. Results:In the contralateral asymptomatic joints, TGD (median, 3.0 mm; 95% confidence interval [CI]: 2.5, 4.6; P , .0001), TT-TG (median, 15 mm; 95% CI: 12.7, 18; P = .008), PHR (median, 1.17; 95% CI: 1.09, 1.2; P = .002), and patellar lateral displacement (BO, 85%; 95% CI: 76.2%, 98.2%; P , .0001) were different from measurements obtained in the control group: TGD median, 5.0 mm (95% CI: 2.2, 7.6); TT-TG median, 10.9 mm (95% CI: 3.4, 20.7); PHR median, 0.92 (95% CI: 0.67, 1.36); and BO median, 63% (95% CI: 59%, 68.4%). OA was detected in 40% of asymmetrical contralateral joints (10 of 25). By using 4D CT data, multiple regression analysis demonstrated that TGD (P = .026) and BO measurements obtained at 30° of knee flexion (P = .047) had an association with the presence of OA. Conclusion:Abnormal morphology and imaging features of OA are relatively common in contralateral asymptomatic joints of young patients with unilateral PI.q RSNA, 2014

Current clinical, radiological and treatment perspectives of patellofemoral pain syndrome

“…The most common height abnormalities are patella alta and baja. 1,2 Patella alta refers to a highriding patella, which can be associated with lateral patellar subluxation and tilt, as the elongated patellar tendon allows increased mediolateral translational mobility and axial rotation of patella due to suboptimal engagement in the apex of trochlear sulcus. It also predisposes to chondromalacia patellae, stripping of patella along its anterior surface (enthesopathy) and patellar tendon rupture.…”

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Editorial Commentary: Measuring Coronal (Mal)Alignment for Patients With Patellar Instability: Tibial Tubercle–to–Trochlear Groove Versus Tibial Tubercle–to–Posterior Cruciate Ligament Distance

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Patellar Chondromalacia in Turkish Population: Prevalence and Relationship with Patella Types

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