Easily Identifiable Bony Landmarks as an Aid in Targeted Regional Ankle Blockade

Summarized by: Neil Washington, DPM
Residency Program: Temple University Hospital, Philadelphia, PA

Title: Easily Identifiable Bony Landmarks as an Aid in Targeted Regional Ankle Blockade

Authors: Schabort D, Boon JM, Becker PJ, Meiring JH

Source: Clinical Anatomy 2005; 18:518-526

PODIATRIC RELEVANCE:
Ankle blocks are commonly employed with foot and ankle surgery. With the use of bony landmarks, a more accurate block can decrease surgery time, decrease amount of anesthetic used, and provide better post-operative pain control.

METHODS:
Ninety-four ankles from 47 cadavers were dissected by first year medical students. Two anatomists agreed upon specific nerves. Nerves not left in original position were excluded. Distance between nerves and bony landmarks were measured with digital calipers (accuracy 0.1 mm). Statistics analyzed using paired t-test, ANOVA and Statistix version 8 analytical software.

Measurements: all measurements were performed in the horizontal plane.
Tibial nerve: 3 measurements from tibial nerve to:

1. most medial aspect of medial malleolus
2. posterior aspect of Achilles tendon
3. most medial aspect of medial malleolus to posterior aspect of Achilles tendon

1. Inferior tip of lateral malleolus to anterior border of sural nerve
2. Most posterior border of lateral malleolus to anterior border of sural nerve

1. Medial border of most anterior aspect of the medial malleolus

1. Anterior aspect of medial malleolus

1. Most anterior aspect of medial malleolus

1. Tibial nerve: found almost directly between medial malleolus and posterior aspect of the Achilles tendon in all specimens.
2. Sural nerve: 25 mm in men, 20 mm in women posterior to inferior tip of lateral malleolus and 20 mm in men, 14 mm in women posterior to most posterior portion of the lateral malleolus.
3. Deep peroneal nerve: 37.5 mm in men, 32 mm in women from most anterior aspect of medial malleolus.
4. Superficial peroneal nerve: MDCN 42.5 mm men, 32 mm women from most anterior aspect of medial malleolus. IDCN directly medial to the medial aspect of the lateral malleolus.
5. Saphenous nerve: 11.5 mm in men, 10 mm in women from most anterior aspect of medial malleolus.

COMMENTS:
This is an extremely useful study for quantifying location of nerves for an ankle block. Bony landmarks are easily found on almost all patients and therefore could be a reliable and reproducible guide to performing superior ankle blocks.

The only downfall of the study would be you could question the reliability/reproducibility of measurements considering embalmed tissue loses a significant amount of water. This can decrease limb diameter and deform soft tissues. Additionally, the sample size could have been larger.

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Disclaimer:

Scientific Abstract Monthly postings are submitted by podiatric surgical residents. The ideas presented are not the opinions of the American College of Foot and Ankle Surgeons (ACFAS), nor are they presented as facts. ACFAS presents this information without any warranty of any kind, expressed or implied, and is not liable for its accuracy nor for any loss or damage caused by the user's reliance on information obtained in these areas.