2025 ISAKOS Congress in Munich, Germany

2025 ISAKOS Biennial Congress Paper


The Lateral Trochlea-Anterior Condyles Angle to Quantify Trochlear Dysplasia

Mauricio Drummond, Jr., MD, Astoria, NY UNITED STATES
Jason Brenner, MS, Bronx, NY UNITED STATES
Steven Henick, MD, Bronx, NY UNITED STATES
Leila M. Alvandi, PhD, Bronx UNITED STATES
Edina Gjonbalaj, BS, Bronx UNITED STATES
Benjamin Levy UNITED STATES
Jacob Schulz, Bronx, NY UNITED STATES
Eric D. Fornari, MD, Mount Kisco, NY UNITED STATES

Montefiore Einstein, Bronx, NY, UNITED STATES

FDA Status Not Applicable

Summary

LTAC values are significant smaller in RPDs than in NRPDs at all four levels of the trochlear groove. This suggests that LTAC can be a good predictor for recurrent patellar dislocations.

Abstract

Objectives: Trochlear dysplasia (TD) is a pertinent anatomical risk factor for patella instability (PI). Quantitative evaluations have demonstrated the impact of TD on stability, patellofemoral kinematics, and contact area/pressure. There have been dozens of proposed methods which effectively evaluate TD; however, none stand alone as the ideal technique. The lateral trochlear anterior condyles (LTAC) angle is a novel technique for describing TD. The purpose of this study is to define the LTAC angle and to describe its anatomical relevance.

Methods

We retrospectively reviewed patients with PI, ages 9-25 at a tertiary care center (2012-2023) to isolate those with recurrent patella dislocations (RPDs) and non-recurrent patella dislocations (NRPDs); age and sex-matched controls were identified from an internal database of patients with anterior cruciate ligament (ACL) injuries. Individuals who had prior surgery on the affected knee and those with suboptimal magnetic resonance imaging studies were excluded. The proximal trochlear groove was defined as the most proximal axial image which showed fully formed cartilage laterally and medially; it was cross-referenced with the sagittal image. Cartilaginous LTAC (Figure 1) was recorded at four consecutive axial images for all participants (LTAC1 – most proximal, LTAC2, LTAC3, LTAC4 – most distal). Independent sample t-tests to compare means between patella dislocators (PDs) and controls and between RPDs and NRPDs, Pearson correlational studies, and a receiver operating characteristics curve to determine area under the curve (AUC) were performed. We utilized Youden’s index to identify optimal diagnostic cutoff values.

Results

A total of 270 knees were included in our analyses (170 PDs, average age = 15.13 ± 2.62; 100 controls, average age = 15.60 ± 1.41). Of the PDs, 106 were RPDs (average age = 15.29 ± 2.45) and 64 were NRPDs (average age = 14.89 ± 2.70). Youden’s index (J) and the corresponding diagnostic cutoff (CO) value is as follows: LTAC1 J=.62, CO<7.0°; LTAC2 J=.68, CO<8.25°; LTAC3 J=.65, CO<11°; LTAC4 J=.55, CO<12.75°. LTAC values is significant different between PD vs control and is strong correlated with PD, LTAC1(4 vs 9.4, p<0.01, r=.88); LTAC2(6 vs11.5, p<0.01,r=.89); LTAC3(7.9 vs13.3, p<0.01, r.89); LTAC4(10.2 vs15.2, p<0.01, r.85). Comparison analysis of LTAC between RPD vs NRPD demonstrates significant difference LTAC1(3.5 vs 4.7, p=0.03); LTAC2(5.3 vs 7.1, p<0.01); LTAC3(7.4 vs 8.8, p=0.03); LTAC4(9.6 vs 11.2, p=0.02).

Conclusion

The LTAC effectively represents the degree of TD at all levels of the trochlear groove. It is useful to differentiate PDs from controls and is strongly negatively correlated with PI status; AUC values indicate excellent discrimination. Furthermore, LTAC values are significant smaller in RPDs than in NRPDs at all four levels of the trochlear groove. This suggests that LTAC can be a good predictor for recurrent patellar dislocations. Future work intends to compare LTAC with other measures of TD, to compare cartilaginous and osseus measures of LTAC, and to further describe our suggested cutoff values.