Fig. 35.1
MRI of a PB tendon tear: increased signal intensity due to fluid within the tendon sheath and a splitted tendon
Ultrasound (US) has several advantages in comparison to MRI. It is a less-expensive diagnostic method, can be employed in the outpatient clinic during physical examination and has the ability of dynamic evaluation of the tendons. This makes it easier for diagnosis of dynamic injuries such as (episodic) subluxation, dislocation and tears that are not seen on MRI. It must be noted, however, that the quality of the US is strongly correlated with the quality of the observer. Abnormalities visible on US include tendon thickening, peritendinous fluid within the tendon sheath, ruptures and luxation of the tendons over the fibular tip (Fig. 35.2).
Fig. 35.2
US of the peroneal tendons
More recent, peroneal tendoscopy is gaining popularity as a method for diagnosing peroneal tendon injuries. It is a highly sensitive and specific tool for both static and dynamic injuries and provides an easy transition to (minimally invasive) treatment (Kennedy et al. 2016; van Dijk 2014). With tendoscopy being an invasive diagnostic method for the patient, the primary indication for the procedure is important. These include posterolateral pain due to high clinical suspicion of tenosynovitis, subluxation or dislocation, partial tears or postoperative adhesion (Scholten and van Dijk 2006; van Dijk 2014). Since MRI can sometimes be inconclusive for diagnosing peroneal tendon tendinopathies, peroneal tendoscopy should be performed when clinical suspicion for a peroneal pathology is strong, with or without positive MRI findings (Kennedy et al. 2016; Marmotti et al. 2012). Not only for diagnosis but also for intervention, peroneal tendoscopy is increasingly used. Recent studies report a relatively low rate of complications with reduced costs and earlier recovery when compared with traditional open procedures (Jerosch and Aldawoudy 2007; Kennedy et al. 2016; Lui 2012; van Dijk and Kort 1998; Vega et al. n.d.).
35.6 Treatment
Conservative management is the first step in treatment of peroneal tendon injuries, including a period of rest, immobilization or activity modification. Physical therapy is recommended to strengthen the peroneal tendons and surrounding muscles. In case of dislocation, patients should be immobilized in a lower leg cast for 6 weeks with the foot slightly plantar flexed and inverted, after reposing the tendons back in the retromalleolar groove (Selmani et al. 2006).
If symptoms persist, surgical treatment should be considered. Especially in tears and dislocation, surgery is often required since these pathologies rarely heal itself (Dombek et al. 2003; Redfern and Myerson 2004; Squires et al. 2007). After the release of the SPR and inspection of the tendons from the superior to interior retinacular boundaries, the tendons are debrided and decompressed (Fig. 35.3a). When a tear is found, the tendon is tubularized (Fig. 35.3b). This may not be feasible, however, when a gross part of the tendon is affected (Dombek et al. 2003). A study by Dombek et al. suggested that when more than 50% of the cross-sectional area of the tendon is involved, tenodesis to the intact peroneal tendon might be performed in case one of the tendons is still functional. If both tendons are non-functional, auto- or allograft tendon transfer should be considered (Krause and Brodsky 1998; Redfern and Myerson 2004).
Fig. 35.3
Operative treatment of a peroneal tendon tear. (a) The tendon is debrided and decompressed. (b) Tubularization of the peroneal tendon tear
For the treatment of recurrent dislocation, multiple operative techniques have been described, all with the primary purpose to restabilize the tendons back in the retromalleolar groove by restoring the anatomy of the superior peroneal tunnel. The techniques can generally be divided into four groups: (1) repair or replacement of the SPR, (2) deepening of the retromalleolar groove, (3) bone-block procedures and (4) enhancement of the SPR by rerouting of other soft tissue structures. The latter two are associated with relatively high complication rates, and therefore over the last years, attention is drawn to the first two categories. Studies looking at repair of the SPR, with or without concomitant groove deepening, show promising outcomes, high satisfaction and an 83–100% rate of return to sports (Porter et al. 2005; Raikin et al. 2008). A recent review by our group found that the combination of SPR repair and retromalleolar groove deepening provides significant higher return to sports rates as compared to SPR repair alone (p = 0.022) (van Dijk et al. 2015a)
During operative treatment of peroneal tendon injuries, additional predisposing factors should also be assessed (Bruce et al. 1999; Chilvers and Manoli 2008) since inadequate management of anatomical abnormalities may lead to persistent pain and dysfunction on the longer term. Therefore, additional procedures such as a lateralizing calcaneal osteotomy may be necessary in case of hindfoot varus (Molloy and Tisdel 2003)
35.7 Rehabilitation
Postoperative treatment is very important in successful managing peroneal tendon injuries and should be tailored to every individual patient (van Dijk et al. 2015b). After a tendoscopic procedure, the patient is immobilized in a compressive dressing for 2 days, with the foot in slightly inverted and the ankle at 90 degrees, after which full weight bearing and active range of motion are allowed. In case of an open procedure, including tearing down and repairing of the SPR, the ankle is best immobilized in a splint or cast up to 6 weeks. To promote early range of motion, some surgeons allow early weight bearing after 2 weeks or even shorter. Physical therapy is the key to regain strength and range of motion after a period of immobilization.
A recent review by our group recommends to tailor rehabilitation to every individual patient, for optimal functional recovery (van Dijk et al. 2015b).
Conclusion
Peroneal tendon injuries account for a significant part of posterolateral ankle complaints following acute ankle inversion trauma and can be very debilitating for patients. To prevent the tendons from chronic damage, early diagnosis and treatment are essential. MRI and US are helpful tools in diagnosing peroneal tendon injuries, but patient history and clinical examination are the key to an accurate diagnosis and choosing the optimal treatment strategy. Conservative management is still the first attempt of treatment, but surgical intervention is often necessary. In general, good to excellent results have been described after surgical intervention. To prevent treatment failure or reinjuries of the tendons, predisposing factors such as pes cavus or hindfoot varus should be addressed during initial surgery.
References
Borton DC et al (1998) Operative reconstruction after transverse rupture of the tendons of both peroneus longus and brevis. Surgical reconstruction by transfer of the flexor digitorum longus tendon. J Bone Joint Surg 80(5):781–784CrossRef
Chilvers M, Manoli A 2nd (2008) The subtle cavus foot and association with ankle instability and lateral foot overload. Foot Ankle Clin 13(2):315–324, vii. doi:10.1016/j.fcl.2008.01.003 CrossRefPubMed
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