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Ultrasonographic Findings After Achilles Tenotomy During Ponseti Treatment for Club Feet. Is Ultrasound a Reliable Tool to Assess Tendon Healing?

Sunday, October 21, 2012: 8:14 AM
Melrose (Hilton Riverside)
Pierre Nasr, MBBS, BSC, MRCS, Andreas Rehm and Laurence Berman, Orthopaedics, ADDENBROOKES HOSPITAL, Cambridge, United Kingdom

Purpose

The Ponseti technique is a well recognised technique in the management of idiopathic congenital talipes equinovarus with high success rates. The natural history of this tenotomised tendon is not well understood, although some authors have assessed this healing phase ultrasonographically.  There are varying reports in the literature regarding the length of time is takes for these tendons to heal.  We aimed to establish the appearance of the achilles tendon post tenotomy, to define the process of healing and also compare these tendons with normal controls and  patients that had undergone an achilles tenotomy more than 12 months previously for a congenital clubfoot deformity.  We are not aware of any studies that have looked  at these 3 groups of patients.

Methods

We prospectively studied 20 achilles tenotomies in 15 patients with idiopathic congenital talipes equinovarus in our new patient group. Tenotomies were performed percutaneously in the operating room using a size 15 blade with the patient under a general anaesthetic. The tendon was palpated above the insertion following which the  blade was inserted on the medial border of the tendon, cutting the tendon towards its lateral border. This usually gave an immediate increase of passive foot dorsiflexion of about 40 degrees and an obvious palpable gap indicating complete dissection clinically.

At intervals coinciding with routine follow up in our clinic, children underwent ultrasonographic evaluation of their tenotomy with us obtaining longitudinal and axial plane pictures.

During this examination, we were able to evaluate the ultrasound structure of the tendon.  Comments regarding the completeness of division, obliquity of the tenotomy and gap measurements were recorded.  We assessed the dynamic integrity of the tendon during passive ankle dorsiflexion and plantarflexion and the serial appearances of the tendon were recorded attempting to highlight when structural continuity was achieved.

Results

We noted marked variations in the immediate post operative appearance of the tendon, in particular, the level, obliquity and completeness of the surgical division.  Good passive ankle dorsiflexion was achieved in all patients despite ultrasonographically incomplete sectioning of the tendon in 70% of patients.  

Conclusion

In our opinion it is impossible to accurately measure gaps between the tenotomized ends because this changes depending on the angle of the probe, the obliquity of the cut and variable position of the foot. There is a large variation in gap measurements that can be obtained between the retracted tendon ends. The width measurement is also inaccurate and varies with the position of the probe which is not reproducible and will change from scan to scan.  This highlights pitfalls in previous papers measuring the distances producing apparent accurate figures to quantify these gaps. There also does not seem to be any beneficial clinical correlation to patient outcome.