Clinical Pearl: FAI, The Rectus Femoris and Dry Needling

How Dry Needling can be used to treat Femoro-Acetabular Impingement (FAI)

Although Femoro-Acetabular Impingement (FAI) somewhat mysteriously burst on to the scene roughly a decade ago, it was actually first described by Dr. Ganz and colleagues in 1999 as a secondary complication following a hip realignment procedure.1 They described the abnormal abutment of the anterior aspect of the hip components, thus leading to pain in the joint. It is now accepted that FAI poses a primary etiological premise in the cause of anterior hip pain in younger persons, specifically those pushing the biomechanical limits of the hip joint, such as in athletics.

Not only does it limit the functional ability of these individuals, it also potentially leads to breakdown of the joint via degradation of the smooth articular cartilage around the acetabulum or femur (arthritis). It can also damage the crescent shaped acetabular labrum, which serves to slightly deepen the acetabulum, provide proprioceptive feedback, and ultimately restrain the joint.

Similarly seen with damage to the menisci of the knee, physical disruption of the labrum can alter hip joint mechanics, lead to chondral injury and subsequent degenerative osteoarthritis, and also manifest chronic joint effusion. Joint effusion is specifically important as it also produces arthrogenic (joint generated) inhibition of the surrounding musculature (notably the gluteals and iliopsoas). This phenomenon happens in every joint, and serves as a protective mechanism to limit the utility of the region and thus allow healing to take place. Think of the quadriceps inhibition, which can be upwards of 80-90% decreased after a simple arthroscopy of the knee.2,3

So what do the rectus femoris and dry needling have to do with any of this?

Most patients with complaints of FAI report “pinching” type pain deep anterior and medial to the AIIS, usually around the groin. The pain is typically reproduced with hyper flexion in the sagittal plane and exacerbated with internal femoral rotation in a flexed position. It is truly tough to identify the specific structure generating the pain due to depth of the symptom and the amount of overlying structures in the region. Although many reports are quick to label the labrum as the causative factor, a multitude of published literature has presented large rates of labral tears in asymptomatic individuals as well.4

Having a particular interest in hip pain, I see quite a bit of FAI type pain referrals, mostly with the intention to help clarify the picture and identify pain generators. After taking Functional Dry Needling Level 2 and the Advanced courses, I began to study both the intimate relationship of the rectus femoris reflected head (pictured right), and the underlying role of two-joint muscles throughout the body. Two-joint muscles, when compared to their single-joint counterparts, tended to serve a more proprioceptive purpose, which I thought could have dramatic influence on the neuromuscular strategy of the joint.

Putting the pieces together and having broadened my treatment spectrum with the Advanced dry needling course, I put together an algorithm linking FAI, the rectus femoris, and the joint capsule along with a nice fancy modality to treat them. Appreciating the joint’s impact on the surrounding musculature, especially when effused or irritated, it would stand to reason that the rectus would be inhibited due to its intimate relationship to the anterior joint capsule. Similar to the rotator cuff of the shoulder when understanding “posterior shoulder impingement”, it’s possible the anterior joint capsule is not being tensioned and cleared during hip flexion due to the lack of rectus femoris feedback as a 2-joint sensor. Rectus_Femoris_Dry_Needling
Figure 1

Based on this thought process, I began dry needling patients directly into the proximal aspects of the rectus femoris, as well as the anterior joint capsule. The goal was to both provide inhibition of the “joint alarms” in the capsule, while also facilitating the rectus to help out the capsule.  In essence, the treatment was creating a reset of hip mechanical function.  I was seeing instant improvements in flexion range of motion, both actively and passively. Was I correcting the labral tear or cartilage?  No chance. But I do believe I was changing the motor pattern, and the neuromuscular system is much more powerful than we think!

Certainly not every patient responded so completely, and yes, groups of patients still ultimately flushed into the surgical management basket as well. However, an ever-growing group of patients did ultimately succeed and continue to do well moving forward. Not only does it speak to the power of dry needling as a tool, but it also further emphasizes the neuromuscular component of the interventions we provide and the changes we make. The needle reaches further than we can manually, and in many cases packs more punch!

Happy Needling!

1. Myers S, Eijer H, Ganz R. Anterior femoro-acetabular impingement after periacetabular osteotomy. Clin Orthop. 1999;363:93-99 

2. Rice D, McNair P. Quadriceps arthrogenic muscle inhibition: neural mechanisms and treatment perspectives. Semin Arthritis Rheum. 2010; 40(3):250-66. 

3. Holm B, Kristensen M, Bencke J. Loss of knee-extension strength is related to knee swelling after total knee arthroplasty. Arch Phys Med Rehabil. 2010; 91(11):1770-6. 

4. Aydingöz U, Oztürk MH MR imaging of the acetabular labrum: a comparative study of both hips in 180 asymptomatic volunteers. Eur Radiol. 2001; 11(4):567-74.