Peroneal Tendon Instability in Calcaneus Fractures: A Commentary.

Abstract

Like many high-energy bony injuries, a calcaneus fracture is more than just the “fracture.” In this issue of FAI, Vosoughi et al10 provide a large-scale cross-sectional evaluation of peroneal tendon instability in the setting of displaced intra-articular calcaneal fractures. They compared preoperative imaging findings to intraoperative stress testing to quantify the prevalence of peroneal dislocation in one of the largest cohorts to investigate this issue. Similar to previous studies, they noted a significant rate of peroneal tendon dislocations.1,3,7 Despite finding some statistical CT associations, they determined that imaging alone was not sufficient to replace intraoperative stress testing of the peroneal retinaculum stability. As with previous clinical studies, the authors recommend intraoperative stress testing of the peroneal retinaculum to determine stability. There is a lack of studies comparing treatment of acute to chronic peroneal tendon instability, but evidence shows that chronic peroneal dislocation often fails nonoperative management. Acute repair allows for primary repair of the retinaculum, whereas delayed repair of peroneal dislocation often warrants more complex procedures such as fibular groove deepening or tendon rerouting procedures.8 Chronic and recurrent dislocation of the tendons can lead also to tendon tearing, which leads to more challenging repair and reconstruction, or even irreparable tendons. These larger procedures require larger incisions, which lead to risks of soft tissue complications and nerve injury, especially in the proximity of prior calcaneal trauma and approaches.8 Additionally, this adds an additional surgery and recovery timeline to the patient, who has already endured immobilization, therapy, and loss of work after their trauma. Therefore, early diagnosis of peroneal instability is important to maximize recovery after treatment of the primary injury and reduce the need for secondary stabilization procedures. Vosoughi et al10 have provided a large retrospective cohort to corroborate prior studies, suggesting a notable prevalence (16.7%) of peroneal tendon instability in the setting of calcaneus fracture. These higher-energy injuries already lead to significant functional limitations,9 and it is important to identify any features possible to improve patient outcomes. Although some patient anatomy6 may predispose patients to peroneal instability, the calcaneus fracture has a significant association because of the classic widening and lateral displacement of intra-articular calcaneus fractures in light of the anatomic relationship with the peroneal tendons and confluence of the peroneal retinaculum and calcaneus lateral wall. The authors determined that CT findings can be somewhat predictive of peroneal dislocation, but the prevalence was grossly overstated with imaging alone when compared to intraoperative stress testing. Additionally, there was no particular mechanism of calcaneal injury associated with peroneal instability, so suspicion must remain high in all fractures. This reinforces the importance of intraoperative surgeon evaluation of the superficial peroneal retinaculum and tendon stability. This is a key point and has been emphasized by the authors, and corroborates with prior studies.1,3,7 Although the gold standard determination of tendon stability is intraoperative testing, the authors add to the body of evidence that preoperative imaging is a useful modality for prediction of potential peroneal dislocation or subluxation and should be studied closely. The value of CT scans, routinely obtained for bony injuries, in soft tissue evaluation is often underappreciated. However, it can be useful in identification of soft tissue structure displacement or entrapment in other injuries around the ankle as well.2,4 In that study, the authors noted a high rate of peroneal tendon instability with imaging findings of lateral malleolar “fleck sign,” fracture-dislocations of the calcaneus, and large lateral wall extrusion (>1 cm lateral to the fibula).3 Although this preoperative imaging is important, we have found peroneal tendon instability in injuries where the preoperative imaging did not show any instability. We agree with the authors that intraoperative stress testing of the peroneal retinaculum should be routinely performed on every operatively treated calcaneus fracture. High suspicion for peroneal dislocation may even be worthwhile indication for operative intervention in a fracture that is borderline by other criteria. The peroneal tendons are routinely isolated during the fracture approach, regardless of extensile lateral or sinus tarsi incisions. Evaluation of the tendons should be performed after anatomic restoration of the calcaneal morphology. At times tendon dislocation is obvious; however, in many cases, the instability is found with a stress test. The stress test used in this study is performed by using a small clamp that is placed into the retrocalcaneal groove. Once identified, these injuries require additional treatment. The authors describe multiple techniques for repair of the SPR, including working through the extensile lateral flap, a separate incision or extension of sinus tarsi approach, 1182628 FAIXXX10.1177/10711007231182628Foot & Ankle InternationalCiufo and Ketz article-commentary2023