Aim: To evaluate the accuracy of ultrasound to locate the gastrocnemius musculotendinous junction (GMTJ) prior to surgery. There is no clear clinical method to precisely localise this junction, either in the paediatric or adult populations.

Method: Twenty calves in 12 paediatric patients with a diagnosis of spastic gastrocnemius muscle (GM) contracture underwent ultrasound examination prior to slide lengthening (Strayer). Surgeons did the ultrasound examination after only a short introduction to the method, using a portable ultrasound machine (Sonosite 180 PLUS) with a linear (5–10 MHz frequency range) transducer.

Only the GMTJ of medial head was located as it usually has a lower attachment and is thicker. The soleus muscle has short multipennate fibres running obliquely between aponeuroses overlying its anterior and posterior surfaces. GM has long parallel fibres and merges distally with the posterior aponeurosis of the soleus muscle. The GMTJ has a unique conical appearance on ultrasound. Pre operative skin markings were compared with the location of GMTJ during surgery.

Results: All ultrasound-guided locations of GMTJ were found to be accurate within 5mm at time of surgery.

Conclusions: This study indicates that ultrasound of the calf muscles by a surgeon prior to surgery is an accurate and reliable way of centering the incision over the GMTJ. The distinct morphological structure of the soleus muscle and overlying GM heads means that even surgeons with little ultrasound experience can perform the examination.