VMO and Patellofemoral Pain

I have previously discussed Patellofemoral pain and the evidence base behind the diagnosis, pre-disposing factors and treatment of this disorder (link here).

As discussed in the above-mentioned post a significant volume of literature would suggest that the clinical utility of “clinical tests” for diagnosing Patellofemoral pain is poor, that being they lack specificity, sensitivity, and have poor positive and/or negative likelihood ratios. From my readings, none would have utility as a screening or diagnostic test.

What I thought I might turn my attention to in this post to is that pesky VMO (Vastus Medialis Obliquus) muscle.

I think there are still very common held beliefs out there that VMO is a critical muscle in patellofemoral pain disorders and that ALL patients with patellofemoral pain have deficiencies in VMO size in comparison to that “terrible” VL (Vastus Lateralis) which is overactive and/or of normal size.

I recently read the following systematic review by Giles et al (2013). The authors investigated whether quadriceps atrophy was present in the affected limb of individuals with patellofemoral pain (PFP). A systematic search of the literature was conducted to identify studies that measured the size of the quadriceps in individuals with PFP. Meta-analyses were then performed to determine whether a difference was present in quadriceps size between the limb with PFP and comparison limbs. Separate meta-analyses were performed for quadriceps size measured as girth and quadriceps size measured with imaging (thickness, cross sectional area, and volume). Conclusions being:

• Quadriceps muscle atrophy was shown to be present in PFP when analysed by imaging, but not girth measures.
• Insufficient data was available to determine if there was greater atrophy of VMO than VL.

So a common clinical view is once again not necessarily supported by the literature…..

Now I am not stating that patients who present with PFP never have atrophy of VMO compared to VL……what I am suggesting  is that the research is inconclusive regarding this issue. I would however argue that there are “gurus” within our profession who would strongly suggest that VMO is an essential muscle to be targeted/treated due to issues with decreases in its size compared to VL, and that this issue with VMO is present in all PFP patients. The research literature would appear to disagree with this.

I realise we haven’t covered other topics relating to VMO/VL timing etc. Its on the list….

Thanks for reading.

References:

Giles LS, Webster KE, McClelland JA, Cook J. Does quadriceps atrophy exist in individuals with patellofemoral pain? A systematic literature review with meta-analysis. Journal of Orthopaedic & Sports Physical Therapy (Early Access Issue) pp: 1-30 doi:10.2519/jospt.2013.4833.