Increased TT-TG and Sulcus Angle are Associated with Patella Osteochondritis Dissecans

Increased TT-TG and Sulcus Angle are Associated with Patella Osteochondritis Dissecans

Emilie Lijesen, BS, UNITED STATES Akshitha Adhiyaman, BS, UNITED STATES Olivia C. Tracey, BA, UNITED STATES Joshua T. Bram, MD, UNITED STATES Nnaoma M Oji, MD, UNITED STATES Danielle E. Chipman, BS, UNITED STATES Shae K Simpson, BS, UNITED STATES Douglas Mintz, MD, UNITED STATES Peter D. Fabricant, MD, MPH, UNITED STATES Daniel W. Green, MD, MS, UNITED STATES

Hospital for Special Surgery, New York, New York, UNITED STATES


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Anatomic Location

Anatomic Structure

Diagnosis / Condition

Patient Populations

Diagnosis Method

MRI

Sports Medicine

Cartilage


Summary: Patients with patella osteochondritis dissecans (OCD) display elevated tibial tubercle to trochlear groove (TT-TG) distance and high sulcus angle, as well as an increased risk of post-operative patella dislocation, as compared to those with an OCD lesion of the medial femoral condyle (MFC).


Background

Osteochondritis dissecans (OCD) lesions are most commonly found in the medial femoral condyle (MFC). Patella OCD lesions have also been described, with limited information available regarding their characteristics. Patellar maltracking and increased patellofemoral contact pressures due to abnormal patellofemoral morphology may play a role in the development of patella OCD. This study aimed to evaluate the differences in patellofemoral morphology between patients with patella OCD and MFC OCD. We speculate that patella OCD patients will demonstrate increased trochlear dysplasia compared to MFC OCD patients and that patients with patella OCD are at greater risk for post-operative dislocation.

Methods

Patients ≤ 18 years old diagnosed with either a patella or MFC OCD lesion at a single tertiary care hospital between January 2016 and May 2023 were selected. None of the patients with patella OCD included in this study had a history of patellofemoral instability (PFI). Caton-Deschamps Index (CDI), cartilaginous bony height (CBH), trochlear depth, patellar tilt, lateral patellar displacement, cartilaginous sulcus angle (CSA), bony sulcus angle (BSA), and TT-TG distance were assessed on preoperative or most recent magnetic resonance imaging (MRI). Patients were matched 1:2 based on sex and chronologic age (± 2 years) between patella OCD and MFC OCD cohorts.

Results

A total of 40 extremities in 34 patients with patella OCD were matched to 80 extremities in 73 patients with MFC OCD (mean age 13.9 ± 2.2 years; 23.3% female). Patients with patella OCD had significantly greater TT-TG distance (13.35 ± 4.07mm vs. 11.55 ± 4.15mm, P=0.03), as well as higher CSA (150.63 ± 7.20 mm vs. 128.09 ± 14.07 mm, P<0.001) and BSA (144.7 ± 7.78 mm vs. 137.37 ± 9.62 mm, P<0.001) compared to patients with MFC OCD. There were no significant differences in CDI, trochlear depth, patellar tilt, lateral patellar displacement, or CBH. 40% of patella OCD patients compared with 20% of MFC OCD patients had a TT-TG distance greater than 15mm. The patella OCD group had a 3.7 times greater risk of post-operative patella dislocation compared to the MFC OCD group.

Conclusions

This study demonstrates that elevated TT-TG and high sulcus angle are associated with patella OCD. In addition, patients with patella OCD demonstrated a nearly four-fold higher risk of post-operative dislocation compared to an age- and sex-matched group with MFC OCD despite no history of prior patella dislocation.