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Ultrasound found unreliable for assessing post-tenotomy healing during Ponseti treatment
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BIRMINGHAM, England — Ultrasound appeared to provide surgeons with misleading and inaccurate information when assessing Achilles tendon healing after tenotomy during Ponseti treatment for clubfoot deformity. This is in contrast with findings from previous studies, according to a presenter at the British Orthopaedic Association Congress, here.
Previous studies, he said, have shown that ultrasound is a useful and accurate method to follow the healing tenotomy and based on ultrasound and clinical assessment, the reported length of time for tendons to achieve continuity in these studies varied from 6 weeks to 45 months.
“Clinical continuity does occur well before ultrasound continuity despite incomplete sectioning of the tendon in 70% of our cases, which is at variance with previous reports,” Pierre Nasr, MBBS, BSc, MRCS, of Addenbrookes Hospital, in Cambridge, United Kingdom, said. “Intraoperative ultrasound is therefore unlikely to be beneficial and may cause a surgeon to make a further pass of the scalpel blade, which increases the risk for iatrogenic injury.”
Ultrasound for follow-up
Nasr and colleagues monitored post-tenotomy healing in 15 patients (20 tendons) aged 2 months to 11 months old using high-frequency ultrasound. They followed up these patients for 6 months to 14 months.
In addition, they evaluated nine controls and nine patients (11 tendons) who had an Achilles tenotomy at age 2 months to 5 months old, which was 7 years or more prior to the study.
Immediate postoperative ultrasound findings revealed a marked variation in the distance of the tenotomy from the calcaneum as well as variations in obliquity and completeness of surgical division.
Researchers performed the scans at varying intervals from the immediate postoperative period to within 4 weeks of tenotomy, at 4 months and up to 14 months postoperatively.
Abnormal tendon appearance
Ultrasound revealed incomplete tendon division in 70% of patients; however, all patients achieved a sufficient clinical effect of passive dorsiflexion. The last scan was performed at a mean of 8.5 months postoperatively. Sixty-five percent of tendons did not achieve a normal appearance on serial ultrasounds at up to 14 months postoperatively. Among patients who had undergone previous tenotomy, who were scanned at a mean of 60 months postoperatively, about 60% of the tendons were normal. However, “all patients demonstrated abnormal appearances such as heterogeneous appearance of the tendon, loss of the normal striated pattern, fissures and increased dimensions,” Nasr said.
Nasr also reported pitfalls when it came to using ultrasound to define stages of healing, which were not described in previous studies. “One of the features that we noted as causing total confusion with the ultrasound is anisotropy, where the ultrasound appearance depends on the angle that the beam projects toward the tendons,” Nasr said. “It occurs with as little as 2% deviation of the angle of the probe, and it causes fewer returning echoes and much darker images, which can cause some confusion with less experienced ultrasound radiologists,” he said.
Another phenomenon that Nasr observed was a partial voluming effect. “You do get spurious images, which give the impression of fibers being present, but actually the image is derived from intact adjacent fiber, causing confusion in that healing appears to have taken place but in fact has not,” he said. – by Tina DiMarcantonio
- Reference:
- Nasr P. Paper #178. Presented at: British Orthopaedic Association Congress; Oct. 1-4, 2013; Birmingham, England.
- For more information:
- Pierre Nasr, MBBS, BSc, MRCS, can be reached at 99 Duxford Road, Whittlesford, Cambridge CB22 4NJ, United Kingdom; email: pierrenasr@doctors.org.uk.
Disclosure: Nasr has no relevant financial disclosures.
Perspective
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Manuel Cassiano Neves, MD, MSc
The relapse of the deformity in the treatment of idiopathic club foot is still one of the major problems that pediatric orthopaedic surgeons have to face. This can be the result of the failure to achieve an adequate dorsiflexion of the ankle after a tenotomy of the Achilles tendon. Ultrasound has been recommended as a tool to monitor the completion of the tenotomy as demonstrated by Marleix and colleagues and research by Noh and his colleague.
According to Pierre Nasr and his collaborators on this study, ultrasound may give misleading information regarding the completeness of the tenotomy with 70% of cases showing as incomplete. In spite of this, passive dorsiflexion was achieved in all patients, which means that the clinical aspect still plays a major role in the evaluation of the procedures success. In their paper it is also mentioned that there is a wide variation in the healing process of the tendon and it would be interesting to correlate it with the clinical results at long-term follow-up.
References:
Marleix S. Traumatol Surg Res. 2012; doi:10.1016/j.otsr.2012.03.001.
Noh H. Acta Orthop. 2013; doi:10.3109/17453674.2013.784659.
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