Sunday, December 6, 2020

Patient Says She Has Sciatica

Check out her hip range
Recently, a patient came in to see me with pain down her buttocks and leg saying that she has "sciatica". The lower levels of the lumbar spine are notorious for referring pain down to the buttocks and the outside and/ or back of the leg. This is commonly known as 'sciatica' since that is the path of the sciatic nerve, the largest nerve in our bodies. 

Typically sciatica usually affects only one side of the body. She thought she must have hurt her back recently before this buttock pain started. I checked her lower back and it was fine.

Distribution of Sciatic nerve

However, I hit the jackpot when I checked her hip. It reproduced all her 'sciatica' symptoms she was complaining of. 

Femoral and Obturator nerves

How did I know to check her hip? The hip joint is also known to refer pain to the groin and to the front of the thigh, more commonly in the groin due to its nerve supply from the obturator, femoral and sciatic nerves. This is from previous anatomical studies and analysis of pain patterns in patients waiting for hip replacements.

I recall reading an article where researchers did a fluoroscopic guided injection to map out pain referral patterns from the hip. A fluoroscopic injection allows exact locations in the body to be located (under x-ray imaging). Fluoroscopy injections can be used to alleviate pain or in this study's case to identify the origin of pain.  

The researchers had 51 patients (28 female, 23 male) for their study. These patients had hip pathology as evidenced by x-ray or MRI. Pre injection, these patients marked out on a body chart where their pain was (see picture below).

Pain referred from the hip 

The patients were then given a fluoroscopically guided intra-articular (FGIA) injection. There was only local anesthesia and no oral or intravenous sedation for the patients to avoid confounding of results. Only when their pain was reduced by 90% before the FGIA injection was deemed effective. 

Long needle to reach the hip

The researchers found that referred pain to the buttock was the most common (71%). Traditionally accepted referral to the thigh (57%) and groin (55%) were less common. 22% of patients had referred pain to the legs (below the knee).

The referred pain areas in this study (from the hip joint) were similar to previously reported pain patterns observed from the lumbar spine and sacro iliac joints.

This is a very useful study for knowing referral patterns of the hip joint. When a patient complains of pain in their buttocks, groin, thigh or even in the foot, one must not rule out the hip. It is important to note that there is no lumbar spine referral in this study.

Note to self (and other physiotherapists reading this), not all radiating leg pain is 'sciatica'.

Reference

Lesher JM, Dreyfuss P, Hager N et al (2008). Hip Joint Pain Referral Patterns: A Descriptive Study. Pain Med. 9(1): 22-25. DOI: 10.1111/j.1526-4637.2006.00153.x

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