Association of Trochlear Length on Sagittal MRI to Trochlear Dysplasia in Knees With Patellar Instability.

Background

Trochlear dysplasia is a primary risk factor for patellar instability and leads to loss of the osteochondral constraint of the patella. Trochleoplasty techniques include the Peterson grooveplasty, which alters the length of the trochlea; however, a radiographic measurement of trochlear length to support this has not been described.

Purpose

To describe measurements to quantify trochlear length on sagittal magnetic resonance imaging in patients with and without patellar instability and to correlate trochlear length with measurements of trochlear dysplasia.

Study Design

Cross-sectional study; Level of evidence, 3.

Methods

A total of 66 age- and sex-matched knees (36 female and 30 male; mean age, 20.8 ± 4.8 years) were included in this study, of which 33 had patellar instability. Trochlear extension length (TEL) and trochlear alpha angle (TAA) were measured on 3 sagittal magnetic resonance imaging scans (center of the knee, center of the medial condyle, and center of the lateral condyle), and measurements were compared between symptomatic and control knees. Receiver operating characteristic curve analysis was performed, and the area under the curve (AUC) was calculated to describe the accuracy of each measurement to distinguish between knees with and without patellar instability. Linear and multivariate regression analyses were performed to assess the relationship between sagittal measurements and axial measurements of trochlear dysplasia, including lateral trochlear inclination, sulcus angle, and trochlear depth, as well as patient size reflected by the epicondylar distance.

Results

In symptomatic knees, the central trochlea extended more proximally than in control knees, as determined by the TEL (14.0 ± 3.0 vs 11.5 ± 2.3 mm, respectively;

Conclusion

In knees with symptomatic patellar instability, the central trochlea was found to extend 2.5 mm more proximally than in control knees, and this increase in length correlated with severity of trochlear dysplasia. As radiographic examinations of the trochlea and grooveplasty procedures are often based on the proximal extent of the cartilaginous trochlea, further studies are needed to identify the role of trochlear length in the assessment and treatment of trochlear dysplasia in the setting of patellar instability.

Informations de copyright

© The Author(s) 2023.

Déclaration de conflit d'intérêts

One or more of the authors has declared the following potential conflict of interest or source of funding: Funding for this study was received from the National Institutes of Health (grants R21EB031185, R01AR081344, and R01AR079442 to M.J.T. and F.L.). M.J.T. has received education payments from Kairos Surgical, has received consulting fees from DePuy Synthes, and has a spouse who has received consulting fees from Smith & Nephew. N.P.J.P. has received education payments from SportsTek Medical. AOSSM checks author disclosures against the Open Payments Database (OPD). AOSSM has not conducted an independent investigation on the OPD and disclaims any liability or responsibility relating thereto.