Peroneal Tendon Tears

We Should Consider Looking at the Muscle Instead

Lodewijk C. S. Res, BSc; Tonya Dixon, MD; Bart Lubberts, MD; Joao R. T. Vicentini, MD; Pim A. van Dijk, MD; Ali Hosseini, PhD; Daniel Guss, MD, MBA; Christopher W. DiGiovanni, MD

Disclosures

J Am Acad Orthop Surg. 2018;26(22):809-815. 

In This Article

Abstract and Introduction

Abstract

Introduction:The purpose of this study was to determine whether tears of the peroneus brevis (PB) tendon correlate with increased fatty infiltration of the PB muscle on MRI compared with musculature without clinical evidence of peroneal pathology.

Methods: Ankle MRI scans of patients with PB tendon tearing (tear group) were compared with those of patients without clinical evidence of peroneal pathology (control group). Two reviewers graded the PB muscle belly according to the Goutallier classification.

Results: Thirty patients were included in each group. The mean Goutallier scores for the tear and control groups were 0.52 (±0.72) and 0.05 (±0.15), respectively (P = 0.0019). The level of interobserver agreement between reviewers was moderate (intraclass correlation coefficient = 0.75; 95% confidence interval, 0.57 to 0.85).

Discussion: Patients with PB tendon tear demonstrate markedly higher grades of fatty degeneration compared with patients without peroneal pathology. The Goutallier classification may become a valuable instrument for assessing the severity of a PB tear.

Level of Evidence: Level III—diagnostic study

Introduction

Historically, management of peroneal tears has been based on the severity of tendon pathology and in vivo observation of both tendon and muscle excursion.[1] However, little supportive data that corroborates these subjective observations with the clinical outcome exist; this includes a long-held dogma that 50% involvement of tendon tearing mandates a decision cutoff between sacrifice and repair. When <50% of the tendon is found to be pathological, numerous publications have purported that débridement and primary repair should be performed, with scant comparative outcomes evidence to support this claim.[1–5] When >50% of the tendon is torn or degenerated, many of these same authors instead advocate tenodesis to the adjacent healthy tendon.[1,4–6] If both tendons are markedly involved, or when insufficient muscle excursion is observed intraoperatively, autograft transfer using either the flexor hallucis longus or flexor digitorum longus or a one- or two-stage allograft interposition transfer can be used.[1,4–10] To date, however, no validated studies could be found in the current literature that help the surgeon reliably predict (1) salvageable versus nonsalvageable muscle that might be appropriate for transfer, (2) outcome after autograft transfer versus allograft interposition, or (3) any outcome difference between treatment choices using a 50% cutoff, that is, any difference in salvage of a tendon that is, for example, left with only 33% as opposed to 66% native tendon after débridement and direct repair.

Clinical implications of tendon surgery based on fatty degeneration of respective muscle bellies on MRI have long been known for rotator cuff pathology. Fatty atrophy has been shown to be predictive of both the severity of tendon pathology and the clinical outcome after shoulder surgery, and as a result, its integration into validated treatment algorithms has been broadly applied in upper extremity orthopaedics.[11–16] Fatty degeneration and atrophy likely develop because of loss of muscle load or tension, which alters tendon physiology and increases susceptibility to changes that induce fatty infiltration.[12] The amount of degeneration of the muscle correlates with the quality and functionality of the muscle, and therefore it becomes a reasonable surrogate not only for tear severity but also for outcome prediction after salvage reattachment (incorporation) of that same muscle during tendon reconstruction.[11–20]

With respect to rotator cuff pathology, MRI has been increasingly used to assist with guiding treatment decisions for patients undergoing rotator cuff repair—enjoying excellent outcome predictability.[11–16] Pioneered by Goutallier in 1994, the Goutallier classification system can be used to quantify the degree of fatty degeneration in muscle as observed on CT or MRI—and this has been shown to closely correlate with both tear severity and clinical function after rotator cuff repair in numerous reports over the last 15 years.[11–16] The system consists of five grades: (0) normal muscle, (1) streaks of fat, (2) more muscle than fat, (3) equal muscle and fat, and (4) more fat than muscle[13] (Table 1).

Although preoperative MRI has been commonly used for evaluating the presence and severity of a peroneal tendon tear,[21–24] some studies have demonstrated inconsistency between MRI and intraoperative findings and, to our knowledge, no studies have taken advantage of preoperative MRI assessment of peroneal muscle health before surgery to assist the surgeon with intraoperative decision making.[25–27]

The purpose of this pilot study was to demonstrate whether patients with a peroneus brevis (PB) tear show markedly more fatty degeneration of the PB muscle belly on MRI than do patients without peroneal tendon pathology. To initiate clarification of what we felt to be a potentially important and overlooked test augment that might assist with current decision algorithms as to how best to manage peroneal tendon pathology, we hypothesized that clinically symptomatic patients with PB tendon tears visible on ankle MRI would similarly demonstrate fatty degeneration of the PB muscle compared with patients who lacked any PB pathology, as quantified by the Goutallier classification system. This notion may have implications for future studies exploring both tear severity and treatment optimization based on the clinical outcome.

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