First up, lets consider the function of the psoas major muscle. As well as being a primary hip flexor, it may also assist with lumbar extension in someone with a normal lordosis by forward tilting the pelvis. It assists flexion of the spine when bending as well as some external rotation of the hip. This has some bearing on how best to stretch the psoas which should not only include extension but also some internal rotation. This muscle has also been considered a stabiliser of the spine and hip joint and contributes to upright posture in sitting and standing.
As a pain referral source we often think of the psoas major referring to the anterior thigh and groin, but must remember that pain may also be projected in a vertical direction in a ‘gutter’ along either side of the lower lumbar spine as well as to the sacroiliac region and buttock (Travell & Simons, 1999)
Image courtesy of Primal Pictures Anatomy for Acupuncture
Clinical assessment findings may include restricted active and passive hip flexion (not to be mistaken for FAI signs), hip extension (modified Thomas test) as well as affecting lumbar mobility and control as described above. With unilateral psoas major dysfunction the patient may stand with weight on the opposite side with the foot of the involved leg forwards with the knee slightly bent while leaning slightly towards the involved side. Functionally there may be painful restriction of sitting and getting up from a chair,driving, standing, dressing, walking and climbing stairs. Careful palpation of the psoas major from an anterior approach may reveal alterations in muscle tone as well as taut bands and possibly trigger points. A distal point found deeply along the lateral wall of the femoral triangle may refer to the low back and antero-medial thigh while the more proximal trigger points are found beside and then medially beneath the rectus abdominus will refer to the lumbar region. These may be difficult to identify reliably, however the lower portion of the muscle reveals itself more easily to the skilled examiner.
Trigger points may be activated as secondary to trigger points in other muscles, a sudden fall, prolonged sitting with the knees higher than the hips and being curled up while asleep. Psoas major dysfunction is also associated with back pain during pregnancy, lumbo-sacral and thoraco-lumbar dysfunction, leg length inequality and excess old style full sit ups.
If we have decided that needing a dysfunctional psoas major is the best course of action, what is the best approach? In my mind the answer will be influenced by your knowledge of the relevant anatomy, confidence as a needler and attitude to risk having weighed up the potential benefits.
A recent article by Leung Chia (2014) describes an approach starting at the Acupuncture point BL52 which lies approximately 4 finger widths lateral to the midline from the lower border of the L2 spinous process, on a vertical line joining the medial edge of the scapula and outer border of the lumbar longissimus muscle.
**image courtesy of BMAS points resource
Normally BL52 would be needled at an oblique angle towards the spine to a depth of say 2-3 cm and this Acupuncture point commonly corresponds with a trigger point. When targeting the psoas major, Leung Chia proposes using the same point with the needle inserted to 5-6cm at an oblique angle of 70 degrees towards the spine to avoid penetrating the kidney (usually level with L1 or L2) as well as damaging the nerves which exit the intervertebral foramen (L1-L4). These include the genito-femoral, lateral cutaneous, femoral and obturator nerves given the proximal parts of these nerves lie over the posterior aspect of the psoas major muscle.
To take a more conservative approach which reduces the risk of needling the kidney, one could ensure insertion is simply below the level of L2 (L3-L5 levels only) further down the BL meridian i.e just lateral to the lumbar longissimus muscle and into the iliocostalis muscle at these levels. In this posterior approach, with the patient either in prone or side lying, insertion using a 75-90mm needle is perpendicular and the needle is directed through the iliocostalis lumborum past the transverse processes and into the psoas major which lies just anterior to the transverse processes. (Dommerholt, 2013). The needle may hit one of the nerves lying over the posterior aspect of the psoas in which case there is the option to withdraw the needle with no major harm likely to have been done. A point stimulator can be used to confirm placement of the needle within the psoas major and used to further stimulate the needle if desired.
Another approach would be to position the patient in the side lying recumbent position, as you would to needle the quadratus lumborum, what may be referred to as the lateral approach. Instead of needling into the quadratus lumborum rather to direct the needle at a slightly anterior angle of 10-30 degrees, using a 75 mm needle, into the psoas major muscle (Dommerholt, 2013).
Finally, the lower portion of the psoas major may be needled in supine after palpating and isolating the muscle as it lies just lateral to the femoral artery as the lateral part of the femoral triangle. In this case needle insertion is usually approximately 4cm and as long as the hip joint and femoral artery are avoided this approach presents few risks.
Once the needle is in situ you have the option to leave it alone for a brief period, provide added manual stimulation or use a point stimulator depending on your preference and the patients tolerance. To then remove the needle and review your subjective and objective measures.
Since starting to needle this muscle more regularly (when indicated) I certainly seem to achieve better and quicker results and most of my patients seem to tolerate the deeper needling approach well and have suffered no ill effects. I’d certainly suggest to those of you who are already qualified in Dry Needling or Medical Acupuncture to get out your anatomy textbook (or app?) familiarising yourself with the relevant anatomy and having a go.