Localization of the Lateral Retinacular Nerve for Diagnostic and Therapeutic Nerve Block for Lateral Knee Pain: A Cadaveric Study.
Rakhi G Sutaria, Se Won Lee, Soo Yeon Kim and 2 others
PMID 27346091WHAT IT FOUND
In cadavers, the lateral retinacular nerve branch point averaged 5.5 cm proximal to the lateral knee joint line and 2.6 cm proximal to the lateral femoral epicondyle.
Dye hit the target in 4 of 4 knees at the joint line measurement.
Key findings
01The lateral retinacular nerve branch point averaged 5.5 cm proximal to the lateral knee joint line and 2.6 cm proximal to the tip of the lateral femoral epicondyle.
02Dye injected at the joint line mark targeted the branch point in 4 of 4 knees, and dye injected at the epicondyle mark targeted it in 3 of 4 knees.
03In 4 of 20 cases, the superior lateral genicular nerve branched from the common fibular nerve after a high division of the sciatic nerve.
STILL TO COME
How it was doneWhat they found
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What it does not show
This was a cadaveric study, so it did not test whether a nerve block helps pain in living patients. The dye accuracy test used only 4 undissected lower extremities. Four limbs were excluded because of knee replacement or prior dissection, so the findings may not apply to all knees. The cadavers were 57 to 95 years old, while the paper notes patellofemoral pain syndrome is common in young active people. The authors combined male and female data because they did not expect Q angle to affect the measurements. The authors state the tip of the lateral femoral epicondyle may be harder to palpate reliably than the lateral joint line.
The easy way to misread this
Do not read this as proof that lateral retinacular nerve blocks relieve lateral knee pain. The study was cadaveric and tested dye placement in 4 undissected lower extremities, not pain relief in patients.