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This Article Full Text Full Text (PDF) All Versions of this Article: 36/4/741    most recent 0363546507312171v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Request Reprints Google Scholar Articles by Lin, Y.-F. Articles by Cheng, C.-K. PubMed PubMed Citation Articles by Lin, Y.-F. Articles by Cheng, C.-K. Related Collections Imaging Studies Knee Muscle Patella

Role of the Vastus Medialis Obliquus in Repositioning the Patella

A Dynamic Computed Tomography Study

Yeong-Fwu Lin, PhD, MD^*,, Jiu-Jenq Lin, PhD, PT, Mei-Hwa Jan, MS, PT, Tung-Ching Wei, MS, PT, Hsin-Yen Shih, PT and Cheng-Kung Cheng, PhD^*,

From the ^* Graduate Institute of Biomedical Engineering, National Yang-Ming University, Taipei, Taiwan, Department of Orthopedic Surgery, West Garden Hospital, Taipei, Taiwan, and School and Graduate Institute of Physical Therapy, College of Medicine, National Taiwan University, and Department of Rehabilitation and Physical Medicine, National Taiwan University Hospital, Taipei, Taiwan

Address correspondence to Cheng-Kung Cheng, PhD, Orthopedic Biomechanics Laboratory, Institute of Biomedical Engineering, National Yang-Ming University, No. 155, Sec. 2, Li-Nung St, Taipei 112, Taiwan (e-mail: ckcheng{at}ym.edu.tw).

Background: It has been assumed that patellofemoral pain syndrome results from patellar malalignment. The precise role the vastus medialis obliquus plays in mediating the underlying pathologic abnormality is unclear.

Hypothesis: The morphologic characteristics of the vastus medialis obliquus correlate to patellar malalignment in patients with patellofemoral pain syndrome.

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

Methods: One hundred twelve patients with patellofemoral pain syndrome were studied. Six sets of computed tomography axial images were assessed in which knee flexion was 0°, 15°, or 30° and the quadriceps muscle either relaxed or contracted. Measurements of serial cross-sectional areas of the vastus medialis obliquus and patellar malalignment were made. Correlation and stepwise regression models between the vastus medialis obliquus variables and patellar malalignment (lateral shift and patellar tilt) were calculated. Statistics were calculated on 4 subgroups depending on patellofemoral malalignment type.

Results: Significant correlations were found between measures of cross-sectional areas of vastus medialis obliquus and patellar tilt at 0° and 30° of knee flexion. Using a regression model, it was determined that vastus medialis obliquus is predictive of patellar tilt (R² = 0.078–0.130). This explanation was most apparent in the subgroup of patients with extreme patellar tilt and lateral shift malalignments (R² up to 0.824).

Conclusion: There are significant correlations between vastus medialis obliquus variables and patellar malalignments in extended knees of patients with patellofemoral pain syndrome.

Clinical Relevance: Vastus medialis obliquus muscle function is important to consider in the rehabilitation of patients with patellofemoral pain syndrome, especially those with extreme patellar tilt and lateral shift malalignments.

Key Words: anterior knee pain • patellofemoral pain syndrome (PFPS) • patellar malalignment • vastus medialis obliquus (VMO) • dynamic stabilizer of the patella • computed tomography (CT) imaging