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MRI Grading of Muscle Proposed as Better Way to Assess Peroneal Tendon Tears

Key findings

  • Historically, orthopedic surgeons have focused on the extent of tendon tearing when treating peroneal tendon injuries, but perhaps should also be focusing on the functional status of the muscle attached to the torn tendon
  • The Goutallier classification system, whose use is well-established in the rotator cuff musculature, quantifies the degree of fatty degeneration in muscle as observed on CT or MRI
  • In a retrospective study, patients with a peroneus brevis tear demonstrated significantly more fatty degeneration of the peroneus brevis muscle belly on preoperative MRI than patients without peroneal tendon pathology
  • A prospective, randomized study is underway to determine whether the Goutallier system is valuable towards predicting intra-operative tendon tear severity and clinical outcomes when attempting to repair peroneal tendon tears

Historically, the surgical management of peroneal tendon tears has hinged on the percentage of the tendon that is frayed or torn. While an MRI can be useful to identify the presence of a tear, a definitive assessment relies on direct observation intra-operatively.

This contrasts with rotator cuff tears, where the health of the attached muscles is equally important. As tendons are torn or underused, the attached muscles may become atrophied and undergo fatty degeneration or even retraction.

In the scenario of fatty degeneration, it becomes less likely that one can successfully repair the torn rotator cuff tendon, and patient clinical outcomes are significantly worse than in those where the tendon is torn but the muscle remains normal in appearance. The degree of muscle fatty atrophy has been reliably classified using the Goutallier classification system.

An extensive search by the research team in the Mass General Foot & Ankle Research and Innovation Lab (FARIL) found that no published study has investigated fatty degeneration in the foot and ankle, specifically when treating peroneal tendon tears.

In a retrospective study by Christopher W. DiGiovanni, MD, chief, Foot & Ankle Center at Massachusetts General Hospital, orthopaedic surgeon Daniel Guss, MD, MBA, and colleagues reported in the Journal of the American Academy of Orthopaedic Surgeons,, the FARIL team compared preoperative Goutallier grades in patients with and without peroneal tendon pathology. They found that the Goutallier system might prove to be a valuable approach for the objective assessment of the severity of a peroneal tendon tear.

The researchers consulted a centralized registry that compiles patient data from Mass General and the University of Amsterdam. They identified consecutive patients who underwent preoperative ankle MRI between October 2013 and October 2016 for assessment of a peroneus brevis tear (tear group) or an ankle ganglion (control group).

Based on a pre-study power analysis, 30 patients were included in each group. Two blinded observers graded the incidence and degree of fatty degeneration of the peroneus brevis muscle belly using the Goutallier system and its correlation with the presence of a peroneal tendon tear.

The Goutallier classification consists of five grades:

  • (0) normal muscle
  • (1) streaks of fat
  • (2) more muscle than fat
  • (3) equal muscle and fat
  • (4) more fat than muscle.

The mean score assigned by the two reviewers was 0.52 for the tear group and 0.050 for the control group (= .002).

There was moderate interobserver agreement (intraclass correlation coefficient, 0.74; 95% CI, 0.57–0.85).

The researchers conclude that MRI and the Goutallier system may offer important insight into the muscle function associated with a peroneal tendon tear, including its potential utility as a functional muscle-tendon unit for autograft transfer or receipt of allograft replacement tendon.

For now, they recommend using MRI and the grading system, at a minimum, as an adjunct for identifying and characterizing the presence of a peroneus brevis tendon tear.

A prospective, randomized study is underway to validate the clinical utility and reliability of the Goutallier classification system for the assessment of peroneal tendon tears.

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