Home > Injury Prevention, Movement Dysfunction > Myofascial Trigger Points in the Gluteus Medius and Quadratus Lumborum in those with Patellofemoral Pain

Myofascial Trigger Points in the Gluteus Medius and Quadratus Lumborum in those with Patellofemoral Pain

Reference:

Roach S, Sorenson E, Headley B, San Juan JG.  Prevalence of myofascial trigger points in the hip in patellofemoral pain.  Archives of Physical Medicine and Rehabilitation 2012 Nov 2. pii: S0003-9993(12)01079-9. doi: 10.1016/j.apmr.2012.10.022. [Epub ahead of print]

http://www.ncbi.nlm.nih.gov/pubmed/23127304

What issue was addressed in the study, and why?

Dysfunction of the hip abductor and external rotator muscles is frequently associated with  patellofemoral pain (PFP).  Hip muscle dysfunction is believed to allow for greater hip adduction and internal rotation, thus contributing to medial knee displacement (knee valgus collapse) during functional tasks and ultimately increased patellofemoral contact pressure.  However, the underlying factors associated with hip muscle dysfunction are not clear.

The presence of myofascial trigger points (MTrPs) may contribute to hip muscle dysfunction; however, previous research has not investigated whether MTrPs are actually present in those with PFP.  Therefore, the purpose of this study was to determine the prevalence of of MTrPs in the gluteus medius and quadratus lumborum of individuals with and without PFP.  A secondary purpose was to determine the effects of a single bout of trigger point pressure release therapy on hip muscle strength.

Who were the participants in the study?

A total of 52 participants were enrolled in the study

  • Patellofemoral Pain (PFP) group (n=26): reported general anterior, anterior/medial knee or retropatellar pain for 1 month or longer associated with prolonged sitting, stair ascent/descent, sports, and/or running.
  • Control group (n=26): no previous history of PFP

What did the researchers do for this study?

The dominant leg of all participants was assessed for the following:

  • Peak isometric strength during hip abduction
  • Presence of MTrPs in the gluteus medius
    • 3 locations within the gluteus medius were assessed: 1) proximal to greater trochanter and inferior to iliac crest; 2) anterior to first location (previously described), deep to the iliac creast; 3) posterior to the tensor fascia latae
    • Presence of MTrPs in the quadratus lumborum
      • Assessed in a side lying position with palpation over the lateral third of the lumbar transverse processes

Criteria for identifying the presence of a trigger point included localized taut bands with tenderness, and the presence of a jump sign.

After the initial testing session, the PFP group participants were randomly assigned to a treatment group or sham-control group.  Those PFP group participants assigned to the treatment group received approximately 60-seconds of direct manual pressure over each identified MTrP.  Those in the sham-control group did not receive actual direct pressure over their identified MTrPs, but rather the investigator gently laid their hands over the lateral hip for 60-seconds.

What new information was learned from this study?

Prevalence of MTrPs and strength comparisons between PFP and Control subjects:

The prevalence of MTrP’s was significantly greater in the gluteus medius and quadratus lumborum muscles for the PFP compared to control subjects.  Also, peak isometric hip abduction strength was significantly less in the PFP compared to control subjects.

  • 97% of PFP subjects demonstrated gluteus medius MTrPs compared to only 23% of control subjects
  • 87% of PFP subjects demonstrated bilateral quadratus lumborum MTrPs compared to only 13% of control subjects
    • 93% of PFP subjects demonstrated contralateral side quadratus lumborum MTrPs

Trigger Point Release Therapy:

A single bout of trigger point release therapy did not influence peak isometric hip abduction strength in the PFP subjects.

What are the clinical applications of this study?

MTrPs are more prevalent in the gluteus medius and quadratus lumborum muscles of those with PFP compared to healthy, control subjects.  The presence of MTrPs is also associated with decreased peak isometric hip abduction strength in PFP compared to healthy, control subjects.  These findings suggest that presence of MTrPs in the gluteus medius and quadratus lumborum muscles may be a factor to consider in the prevention and rehabilitation of PFP.  It is possible that MTrPs need be effectively treated to ultimately restore normal gluteus medius and quadratus lumborum function in those with PFP or at risk for PFP.

Unfortunately, a single bout of trigger point release therapy was not sufficient to restore peak isometric hip abduction strength in those with PFP.  It is not clear if the presence of MTrPs was reduced following the single bout of trigger point release therapy as this was not reported by the authors.  The authors indicate that “it was expected that the MTrP compression discomfort would significantly decrease” with the intervention; however, this did not appear to be verified.  Thus, future research is needed to determine if a single bout of trigger point release therapy that effectively eliminates the presence of MTrPs is sufficient to restore muscle strength.

What are the limitations of the study, and what areas should be considered for future research?

It is not clear if the investigators were blinded to the group membership (PFP or control) of the study participants.  If tester blinding was not performed then this may introduce bias into the MTrP prevalence results.

An isolated, single bout of trigger point release therapy may not be sufficient to restore normal muscle function.  Rather a systematic and integrated approach utilizing techniques for muscle inhibition, lengthening, and activation may be required to restore normal muscle function in those with MTrPs.  Future research is needed to examine this approach to restoring normal muscle function in those with MTrPs.

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