Prevalence of chondromalacia patella according to patella type and patellofemoral geometry: a retrospective study

Supratrochlear Rim is Correlated with Isolated Patellar Chondromalacia on Magnetic Resonance Imaging of the Knee

Purpose

To investigate the relationship between the supratrochlear rim and isolated patellar chondromalacia (PC) using magnetic resonance imaging (MRI) scans of the knee.

Methods

Patients without patellofemoral pain (control group) and patients with patellofemoral pain and diagnosed with stage III or IV PC based on MRI (defect group) were retrospectively identified. Patients with a history of patellar subluxation were excluded. We used patient MRI scans to perform 20 anatomical measurements of the patellofemoral joint. We also performed 2 measurements of the anterior femoral curvature. A total of 30 patients (29 ± 8.7 years) were in the control group, and 20 patients were in the defect group (29.4 ± 9.7 years).

Results

The maximum curvature (P < .001) and mean curvature (P < .001) of the anterior femoral condyle were found statistically significantly different between the groups. Patellotrochlear index (P = .03) and Insall-Salvati index (P < .001) were also found statistically significantly different between the 2 groups. Patella type III and trochlear dysplasia grade B were found more common in the defect group.

Conclusions

In this Level III prognostic, case-control study, we have shown through MRI knee measurements that the isolated patellar chondromalacia in patients without a history of patellar subluxation and dislocation is correlated with the increased anterior femoral curvature in combination with patella alta.

The Effect of Patellofemoral Maltracking and Patella Type on Symptomatic Bipartite Patella

Purpose The aim of this study is to investigate the relationship of trochlear dysplasia (TD) and patella type with bipartite patella (BP). Materials and methods A total of 5,081 knee MRIs taken in our institution were reviewed retrospectively. Patients with a history of knee surgery, previous or recent trauma, and rheumatologic involvement were excluded from the study. The MRIs of 49 patients with bipartite/multipartite patella were detected. Three patients were excluded: two patients had a tripartite variant, and one had multiple osseous dysplastic findings. Overall, 46 patients with BP were included in the study. BPs were classified as type I, II, and III. Patients were divided into symptomatic and asymptomatic groups according to the presence of edema within the bipartite fragment and adjacent patella. Patients were examined in terms of patella type, trochlear dysplasia, tuberosity-trochlear groove (TT-TG) difference, sulcus angle, and sulcus depth. Results There were 46 patients with BP (28 males and 18 females) (mean age: 33±9.5 years, range: 18-54). Thirty-eight bipartite fragments (82.6%) were type III and eight (17.4%) were type II. There was no type I BP. Seventeen (36.9%) were symptomatic, and 29 (63.1%) were asymptomatic. Seven of the type II (87.5%) and 10 of the type III (26.3%) bipartite fragments were symptomatic. The frequency and degree of trochlear dysplasia (p=0.007 and p=0.041, respectively) were found to be higher in symptomatic patients. The trochlear sulcus angle was higher (p=0.007) and the trochlear depth was lower (p=0.006) in the symptomatic group. No statistically significant difference was found (p=0.247) in terms of TT-TG difference. Type III and type IV patella were more common in the symptomatic group. Conclusion The current study shows that patellofemoral instability and patella type are associated with symptomatic BP. Patients with trochlear dysplasia, type II BP, and disproportionate patellar facet may have a significantly increased risk of symptomatic BP.