What Is the Relationship Between the Breech Presentation and Femoral Trochlear Dysplasia? An Experimental Study of the Breech Presentation Model in Neonatal Rats

Background: The relationship between breech presentation and trochlear dysplasia had been confirmed. However, the pathological process of breech-related trochlear dysplasia remain unclear. This study aimed to establish an animal model to simulate breech presentation and to analyze the pathological process of the femoral trochlea.Materials and Methods: One hundred and twenty neonatal rats were randomly assigned into a control group and two experimental groups that were swaddled (using surgical tape) to keep the hip flexed and knees extended to simulate human breech presentation for the 5 days (short Swaddling) and the 10 days (prolonged Swaddling) of life. Gross and cross-sectional observation, histological staining measurement in two experimental time points (5, 10 days after birth) were conducted to evaluate the morphological changes of the femoral trochlea.Results: The incidence of trochlear dysplasia increased with the Swaddling time. Rats in the prolonged Swaddling group had the high prevalence of trochlea dysplasia (52 of 60), followed by short Swaddling group (42 of 60). Gross and cross-sectional observation showed a shallower trochlea groove in two experimental groups. Histologicalstaining measurement indicated that the trochlear sulcus angle and trochlear sulcus depth were significantly different between the experimental group and the control group since day 5 and day 10. Conclusion: In this model, breech presentation had a adverse influence on neonatal knees and could induce trochlear dysplasia. What is more, this study also showed that the more time in breech presentation, the more incidence of trochlear dysplasia.

The Difference between Cartilaginous and Bony Sulcus Angles for Patients with or without Patellofemoral Instability: A Systematic Review and Meta-Analysis

The cartilaginous sulcus angle and bony sulcus angle have been widely used to evaluate trochlea dysplasia. The current review aims to evaluate (1) whether there is a difference in measurement for cartilaginous and bony sulcus angles, (2) whether both the cartilaginous and bony sulcus angles could be used to differentiate between patients with or without trochlear dysplasia, and (3) whether the same cut-off of 145 degrees, originally used for radiographs, can be applied for the cartilaginous and bony sulcus angles measured on CT and MRI. The review was conducted using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRSIMA) guidelines. A total of 11 publications with 1204 patients were included. All publications reported the sulcus angle to be greater in patients with patellofemoral instability. All publications reported the cartilaginous sulcus angle to be greater than the bony sulcus angle (MD 7.27 degrees; 95% CI: 5.67 – 8.87). The mean cartilaginous sulcus angle for the control group was 141.83 degrees (95% CI: 139.90 – 143.76) while the mean cartilaginous sulcus angle for patients with patellofemoral instability was 156.24 degrees (95% CI: 153.71 – 158.77). The mean bony sulcus angle for the control group was noted to be 133.69 degrees (95% CI: 131.23 – 136.15) while the mean bony sulcus angle for patients with patellofemoral instability was 148.42 (95% CI: 144.02 – 152.82). Both the cartilaginous and bony sulcus angles measured on CT and MRI could therefore be used to differentiate between patients with and without trochlear dysplasia. However, the cartilaginous sulcus angles are significantly higher than that of bony sulcus angles. Different cut off values should therefore be used.

Objective Quantification of Trochlea Dysplasia: Assessment of Morphology Difference Between Control and Chronic Patellofemoral Instability Patients

Aims and Objectives: Trochlear dysplasia is an important risk factor associated with patellofemoral instability, but it remains difficult to classify with consistency. Currently there is no objective way to quantify the dysplasia. The purpose of this study to define and quantify objectively the trochlea morphology by volume and length via computed tomography (CT). Hypothesis: A significant difference in trochlea groove volume and length is present within a cohort of patients with recurrent patellofemoral instability if compared to a control cohort of similar patients. Materials and Methods: One-hundred control patients (136 knees) were retrospectively reviewed and compared to 36 consecutive patients (72 knees) who were treated surgically for recurrent patella instability and known trochlea dysplasia based on a lateral x-ray. Trochlea morphology was analyzed from a pre-operative CT and data presented as trochlear sulcus volume trochlea length. To determine where along the trochlea length dysplasia is most variable, the trochlea length was radiographically divided into thirds, volume was quantified along that section and compared to control trochlea. Results: A significant difference in trochlea morphology exists between cohorts, volume (1.98 vs 3.77 cm3) and length (31.97 vs 34.66 mm). However, there appears to be a gender based difference in trochlea morphology. The trochlea volumetric analysis between the female cohorts (L: 2.02 cm3 vs. 2.94 cm3, R: 1.95 cm3 vs. 2.93 cm3) demonstrated significant less volume in instability patients (p<0.001). The proximal 30% of trochlea contributed the majority of dysplasia difference determined by comparing mean trochlea volume, 95% of the difference. This difference decreased in distal sections, 53% and 32% respectively. The total trochlea length did not appear to be significant (L: p=0.858, R: p=0.913). It appears dysplasia alone may not directly lead to symptoms demonstrated by trochlea volumetric comparisons within symptomatic recurrent patella instability and contralateral asymptomatic patella (p=0.274). Conclusion: The authors believe this reproducible technique can be used to quantify the trochlea morphology into measurements to be used describing the severity of the dysplasia. The data confirms that symptomatic trochlea dysplasia is a “proximal” process affecting early knee flexion contact between patella and trochlea.