Fig. 7
Results of the patellofemoral measurements of eight patients with a problematic TKA, scanned in weight-bearing and non-weight-bearing conditions using low-field MRI to measure the IS and CD ratios, the PTA and the TT-TG distance. The grey areas are the ranges given in the literature for the native knee: Insall-Salvati ratio (0.8–1.2) [17], Caton-Deschamps ratio (0.6–1.2) [20], Patellar tilt angle (30–70) [17], tibial tubercle-trochlear groove distance (10–15 mm) [21]