The Vastus Medialis Insertion Is More Proximal and Medial in Patients With Patellar Instability: A Magnetic Resonance Imaging Case-Control Study

Riccardo Gomes Gobbi; Betina Bremer Hinckel; Paulo Renan Lima Teixeira; Pedro Nogueira Giglio; Bruno Romano Lucarini; José Ricardo Pécora; Gilberto Luis Camanho; Marco Kawamura Demange

doi:10.1177/2325967119880846

The Vastus Medialis Insertion Is More Proximal and Medial in Patients With Patellar Instability: A Magnetic Resonance Imaging Case-Control Study

Orthop J Sports Med. 2019 Dec 4;7(12):2325967119880846. doi: 10.1177/2325967119880846. eCollection 2019 Dec.

Authors

Riccardo Gomes Gobbi¹, Betina Bremer Hinckel², Paulo Renan Lima Teixeira¹, Pedro Nogueira Giglio¹, Bruno Romano Lucarini³, José Ricardo Pécora¹, Gilberto Luis Camanho¹, Marco Kawamura Demange¹

Affiliations

¹ Instituto de Ortopedia e Traumatologia, Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo, São Paulo, Brazil.
² Department of Orthopaedic Surgery, William Beaumont Hospital, Royal Oak, Michigan, USA.
³ Faculdade de Medicina, Universidade de São Paulo, São Paulo, Brazil.

Abstract

Background: The anatomy and function of the quadriceps muscle play a role in patellofemoral stability. Few studies have evaluated anatomic differences in the vastus medialis between patients with and without patellar instability.

Purpose: To compare the anatomy of the vastus medialis using magnetic resonance imaging in patients with patellar instability to a control group.

Study design: Cross-sectional study; Level of evidence, 3.

Methods: A group of patients with patellar instability were sex-matched with a control group with anterior cruciate ligament tears, meniscal injuries, or sprains; patients younger than 15 years were excluded. The anatomy of the vastus medialis was examined by the distance between the distal origin of the vastus medialis in the femur and the medial femoral condyle, the distance from the proximal pole of the patella to the most distal insertion of the muscle and its ratio to the length of the articular surface of the patella, and a qualitative description of the insertion position of the muscle fibers (directly in the patella or the medial retinaculum).

Results: Both groups comprised 78 knees (48 female; 61.5%). The mean age in the control and patellar instability groups was 30.2 ± 7.8 years and 25.6 ± 7.5 years, respectively (P = .001). The distance from the vastus origin to the condyle was 27.52 ± 3.49 mm and 26.59 ± 3.43 mm, respectively (P = .041); the distance from the proximal pole of the patella to the most distal muscle insertion was 17.59 ± 5.54 mm and 15.02 ± 4.18 mm, respectively (P < .001); and the ratio of this distance to the joint surface was 0.586 ± 0.180 and 0.481 ± 0.130, respectively (P < .001). In 75.6% of knees in the patellar instability group, the insertion of the vastus was into the medial retinaculum and not into the patella compared with 52.6% in the control group (P = .003; odds ratio, 2.8).

Conclusion: The distal insertion of the vastus medialis differed in knees with patellar instability, with a more proximal insertion and less patellar coverage relative to controls, and was more frequently found in the retinaculum instead of directly in the patella.

Keywords: anatomy; magnetic resonance imaging; patellar instability; vastus medialis.