SLR - October 2019 - Ashlee Lindgren

Quantitative Magnetic Resonance Imaging Analysis of the Common Site of Acute Achilles Tendon Rupture: 5 to 8 cm Above the Distal End of the Calcaneal Insertion

Reference: Park, Y. MD, Lim J. MD, Choi G. MD, Kim H, MD PhD, Quantitative Magnetic Resonance Imaging Analysis of the Common Site of Acute Achilles Tendon Rupture: 5 to 8 cm Above the Distal End of the Calcaneal Insertion. The American Journal of Sports Medicine. 2019; 47(10):2374-2379

Scientific Literature Review

Reviewed By: Ashlee Lindgren, DPM
Residency Program: SSM DePaul Hospital – St Louis, MO

Podiatric Relevance: The most frequent tendon injury at the ankle joint is an Achilles tendon rupture. When compared to the extensive amount of research on the epidemiology and treatment for Achilles tendon ruptures there has been little research on the pathogenesis referring to the anatomic region. It has frequently been reported most acute Achilles tendon ruptures occur two to six centimeters proximal to its insertion on the calcaneus. This is widely accepted due to the known relative avascularity of this region of the Achilles tendon, known as the watershed area. However, there have been several studies which have shown inconsistent results when attempting to define the watershed area within the Achilles tendon. Due to this inconsistency, there is much controversy around the direct relationship between blood supply and the frequency of Achilles ruptures within that area. This study uses MRI to further analyze the site of acute Achilles tendon ruptures. The authors found a tendency for the site of rupture to be more proximal within the Achilles tendon than previously reported.

Methods: A retrospective study was performed for all patients who had an MRI for diagnosis and preoperative assessment of acute Achilles tendon ruptures from 2011 to 2018. All patients were of Asian ethnicity. A total of 195 patients were included. The rupture site was measured on sagittal imaging. The rupture site was defined as the distance between the most distal fibers of the Achilles tendon at the calcaneal insertion to the proximal end of the distal stump. The relationship between the site of rupture and patient characteristics was analyzed. The intraobserver and interobserver reliability of measurements was determined.

Results: The rupture sites ranged from 1.9 to 10.1 centimeters. The average site of rupture was 6.4 centimeters. The 10th to 90th percentile was 5.0 to 8.4 centimeters. None of the individual patient characteristics showed a significant correlation with the site of rupture. The rupture site did not change significantly over the course of the study and the inter- and intraobserver reliability of the measurement of rupture was excellent.

Conclusions: This study investigated the site of acute Achilles tendon rupture by measuring the distance from the calcaneal insertion to the site of rupture utilizing an MRI. The study found that most acute Achilles tendon ruptures occur five to eight centimeters above the calcaneal insertion. Traditionally, it has been reported that the most common site of rupture was two to six centimeters above the calcaneal insertion. This is more proximal than previously thought. This is important to note when evaluating patients clinically. This study will allow for clinicians to check for tenderness or dimpling with more precision on examination, which can help prevent misdiagnosis. 

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