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Saphenous Nerve Entrapment or Gonalgia Paresthetica

Where is the saphenous nerve located?

The saphenous nerve is the largest sensory branch from the femoral nerve. The nerve travels though the adductor canal where it divides into two main branches the infrapatellar, that supplies sensation from the skin inferior and lateral to the patella, and the sartorial branches that supplies sensation from the medial side of the calf and the dorsomedial ankle and mid foot (Hunter, 1979).

What is saphenous nerve entrapment syndrome?

Saphenous Nerve entrapment is a rare condition that is caused by chronic irritation to the saphenous nerve. The irritation can occur due to several reasons with the most common being compression of the nerve along its path. The most common place that entrapment will occur is at the outlet of the adductor canal.

How does it present?

The cause of saphenous nerve entrapment can be direct though trauma such as a rotational injury or from compression for example a dashboard injury. The saphenous nerve can also be indirectly affected via lumbar disc disease, meniscal tear, or post-surgery. Most commonly during a total knee replacement.

Saphenous Nerve entrapment is described as pain on the inside of the thigh, knee, or calf. The pain is described as dull and achy pain and it may have a burning or electric type feel. Pressure on the inside of the knees will aggravate sensations such as having something resting on the persons lap. Furthermore, walking, sitting, or climbing stairs can be painful (Morganti, 2002).

How do we assess for it?

When we are looking to assess for this condition there are some key findings we are after. Firstly, the pain is located on the inside of the knee and it only appears with exercise or when the saphenous nerves distribution is lightly palpated, most frequently at the adductor canal, the medial joint line or along the proximal third of the leg. Furthermore, specific tests are conducted to stretch the nerve to look for a response or reproduction of the pain, the pain can be a dull ache or burning / electrical type feel.

How do we treat it?

Conservative treatment consists of numerous interventions including activity modification, non-steroidal anti-inflammatory medications, exercise, and neural mobilisation techniques (Morganti, 2002).

If symptoms persist anaesthetic injections can be considered, although have some suboptimal results thus far. If temporary or partial pain relief is obtained after the injection, a second injection 3 to 4 weeks later with corticosteroid may be considered (Worth, 1984). However, if symptoms do not improve a surgical approach should be considered. The surgical options include neurolysis, decompression, and neurectomy.

References:
1. Hunter, L. Y., Louis, D. S., Ricciardi, J. R., & O'Connor, G. A. (1979). The saphenous nerve: its course and importance in medial arthrotomy. The American journal of sports medicine, 7(4), 227-230.
2. Morganti, C. M., McFarland, E. G., & Cosgarea, A. J. (2002). Saphenous neuritis: a poorly understood cause of medial knee pain. JAAOS-Journal of the American Academy of Orthopaedic Surgeons, 10(2), 130-137.
3. Worth, R. M., Kettelkamp, D. B., Defalque, R. J., & Duane, K. U. (1984). Saphenous nerve entrapment: a cause of medial knee pain. The American journal of sports medicine, 12(1), 80-81.

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