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Comparative Study
. 2025 Sep 16;145(1):448.
doi: 10.1007/s00402-025-06059-5.

Assessing the correlation between vastus medialis obliquus cross-sectional area and patellofemoral instability: a comparative magnetic resonance imaging study

Connor James Holmes  1 , Diego Agustín Abelleyra Lastoria  2   3 , Tobias Roberts  4   5 , Vivian Ejindu  4 , Claire Robertson  6 , Caroline Hing  7   8
Affiliations
Comparative Study

Assessing the correlation between vastus medialis obliquus cross-sectional area and patellofemoral instability: a comparative magnetic resonance imaging study

Connor James Holmes et al. Arch Orthop Trauma Surg. .

Abstract

Background: This study investigated the relationship between the vastus medialis obliquus (VMO) cross-sectional area (CSA) and patellofemoral instability (PFI) in both primary and recurrent lateral patellar dislocations (LPD). Our secondary objective was to examine associations between VMO CSA and trochlear dysplasia, tibial tuberosity position, and patellar height in patients with PFI.

Methods: Magnetic resonance imaging (MRI) radiographs were retrospectively analysed for 90 patients with primary acute LPD, 90 patients with recurrent LPD, and 56 patients without LPD (control). Measurements of the CSA ratio of the VMO to the whole thigh in three transverse slices were performed to calculate a mean ratio per patient. Additionally, tibial tubercle-trochlear groove (TT-TG) distance, patellar tilt angle (PTA), trochlear sulcus angle (TSA), and Insall-Salvati ratio (ISR) were measured as part of the Dejour Protocol.

Results: The median CSA ratios in primary (0.04, standard deviation [SD]: 0.02) and recurrent (0.04, SD: 0.02) LPD patients were significantly lower than those in the control group (0.07, SD: 0.02) (P < 0.05). Compared with the primary LPD group, the recurrent LPD group presented significantly greater TT-TG distances (16.0, SD: 4.77 mm vs. 13.0, SD: 4.73 mm; p = 0.0101) and PTA (25, SD: 9.79 degrees vs. 19, SD: 15.76 degrees; p = 0.0071). There was no statistically significant correlation between any parameters of the Dejour Protocol and the VMO CSA ratio in patients with primary or recurrent dislocations (P > 0.05).

Conclusion: Patients with both primary and recurrent LPD demonstrated smaller VMO bulk relative to the rest of the thigh compared with controls. These findings indicate an association between reduced VMO size and patellar dislocation; however, causality cannot be inferred from this cross-sectional analysis.

Level of evidence: IV.

Keywords: Lateral patellar dislocation; MRI; Patellofemoral instability; VMO.

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Conflict of interest statement

Declarations. Conflict of interest: The authors declare no competing interests. Ethical approval and consent to participate: Ethical review was not required as this study was conducted under an audit framework. Consent for publication: Not applicable.

Figures

Fig. 1
Fig. 1
Flowchart displaying the application of inclusion and exclusion criteria to, and subsequent categorisation of, the study group dataset
Fig. 2
Fig. 2
Flowchart displaying the application of inclusion and exclusion criteria for the formation of the final control group dataset
Fig. 3
Fig. 3
Measuring the cross-sectional area of the VMO. The sagittal slice corresponding to the midpoint of the posterior-most part of the patella in the transverse plane was located (A); the proximal patellar pole was identified and the corresponding axial slice (C), as well as the adjacent slices proximally (B) and distally (D) were measured
See this image and copyright information in PMC

References

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