Ultrasound and MRI in the assessment of Achilles tendon rupture: are both necessary?

Ultrasound and MRI in the assessment of Achilles tendon rupture: are both necessary?

REVIEWED BY Dr Michelle Fenech, FASA | ASA SIG: Musculoskeletal

REFERENCE | Authors: Moretti L, Solarino G, Pignataro P, Baglioni M, Vicenti G, Bizzoca D, Piazzolla A, Alberotanza V, Moretti B

WHY THE STUDY WAS PERFORMED

Achilles tendon rupture is one of the most common tendon injuries in the adult population. The distinction between complete and partial tears, the gap size between the ruptured ends of the tendon and distance between the tear and the calcaneus are criteria which can guide the treatment of Achilles tendon ruptures. These can be determined sonographically or with magnetic resonance imaging (MRI). This study aimed to define the level of agreement between interoperative findings, US and MRI, regarding reporting of: (1) complete versus partial tears, (2) the gap between tendon ends, (3) the distance of the tear from the calcaneus. This was to determine the best imaging modality to use to plan management of patients post Achilles tendon injury.

HOW THE STUDY WAS PERFORMED

A prospective observational study was conducted to evaluate ultrasound and MRI findings in acute Achilles tendon ruptures which were treated surgically. Thirty-four participants were included in the study. Participants were clinically suspected to have a complete Achilles tendon rupture. Thirty-one participants had positive Thompson Test; 33 had a positive Matles Test, and all presented with a palpable gap in the region of the Achilles tendon. They all underwent dynamic US and static MRI examinations within 40 hours of injury to define (1) whether the tear was complete or partial, (2) size of the gap between tendon ends, and (3) the distance of the tear from the calcaneus. The results were compared with interoperative findings and measures.

Measurements of the gap between tendon ends and distance from the calcaneus via US and MRI in this study were performed with the foot in neutral position (0-degree plantar flexion). During surgery, the foot was placed in the same positioning as imaging and the gap (when present) and the distance of tear from calcaneus was measured.

“Ultrasound, when performed by an experienced sonographer, is accurate in defining the main features of acute Achilles tendon ruptures.”

WHAT THE STUDY FOUND

Partial or complete tears: From 34 participants, 4 were intraoperatively identified to have partial tears. US correctly identified all 4 partial tears. MRI had reported complete tears of all 34 participants. MRI reported a partial tear (identified complete sonographically), which was conferred intraoperatively as complete.

Size of the tendon gap and distance from calcaneus: There was good agreement between the size of the gap between torn tendon ends and the distance of the tear from the calcaneus between interoperative evaluation, US and MRI.

US was found to be accurate in defining the main features of acute Achilles tendon rupture.

RELEVANCE TO CLINICAL PRACTICE

Imaging of the Achilles tendon post injury is used to guide treatment. Treatment of Achilles tendon ruptures can be grouped into surgical and non-surgical (conservative) methods. There is a growing use of functional rehabilitation programs for the treatment of Achilles tendon rupture. Surgical repair has been reported to have a lower re-rupture rate, however, can have surgical complications. Dynamic ultrasound has the advantage that it can demonstrate the tendon ends moving apart and moving together with altering degrees of plantar flexion. This enhances identification of complete tears of the Achilles tendon. The gap size between the ruptured ends of the tendon can be used as a tool to decide on the treatment of Achilles tendon ruptures. This gap size can be measured with the foot in plantar flexion (toes pointed) or neutral position (plantar aspect of the foot perpendicular to long axis of the lower leg). If the gap size is reported sonographically, the foot position and degree of angulation of plantar flexion should be documented.