Abstract
Management of disorders of the peroneal tendons is not difficult, yet the results of treatment are not as predictable as expected. With peroneal tendon injury, prompt operative intervention seems to be more critical to a good outcome than with other tendon disorders—for example, injury to the posterior tibial tendon, for which a plethora of effective nonoperative treatment alternatives are available. We have found that repair of chronically ruptured tendons to be unpredictable. We have not found prolonged nonsurgical methods of treatment to be very successful with peroneal tendon disorders. Tenosynovitis may settle down (if the underlying cause is a self-limited process or one amenable to treatment by noninvasive means), yet progression to more extensive tears of the involved tendons is common. Magnetic resonance imaging (MRI) might be expected to be a useful diagnostic modality in the management of this spectrum of disorders; however, given the 35% rate of positive findings in asymptomatic individuals, one must not rely solely on radiographic findings to determine the need for operative intervention. Therefore, we rely more on clinical evaluation more than on MRI for decision making, although it may be considered to evaluate for other concomitant pathology or verification of peroneal disease in equivocal cases.
Key Words
peroneal, peroneus brevis, peroneus longus, tendinosis, tenosynovitis, subluxation
Introduction
Management of disorders of the peroneal tendons is not difficult, yet the results of treatment are not as predictable as expected. With peroneal tendon injury, prompt operative intervention seems to be more critical to a good outcome than with other tendon disorders—for example, injury to the posterior tibial tendon, for which a plethora of effective nonoperative treatment alternatives are available. We have found repair of chronically ruptured peroneal tendons to be unpredictable. The old rule that if more than 50% of the tendon is torn then a repair cannot be performed successfully has been proven not to be correct on carefully simulated biomechanical loading studies. However, once torn, what is the capacity for tendon healing to occur?
We have not found prolonged nonsurgical methods of treatment to be very successful with peroneal tendon disorders. Tenosynovitis may settle down (if the underlying cause is a self-limited process or one amenable to treatment by noninvasive means), yet progression to more extensive tears of the involved tendons is common. With such tears, the likelihood is that the pathologic changes will progress, leading to a far worse clinical condition with deformity and fewer options for reconstruction. This is particularly common, for example, with stenosis at the level of the peroneal tubercle, where patients will present with pain that is quite localized. The compression from the separate retinacula at this level against a large peroneal tubercle on the calcaneus will eventually cause complete rupture. If treated early enough, simple endoscopic decompression of the stenosis or an open release of the tendon sheaths and removal of the tubercle is very effective early treatment. The same applies to a recurrent dislocating peroneal tendon. Many patients will state that the popping is audible and they feel the rubbing of the tendon over the fibula when it subluxates or dislocates, but that it is not painful. Inevitably if the subluxation-dislocation is left untreated, the tendon undergoes attrition and rupture. If the tendon remains chronically dislocated, this is not the case, since there is no continuous rubbing over the edge of the fibula.
Magnetic resonance imaging (MRI) might be expected to be a useful diagnostic modality in the management of this spectrum of disorders; however, given the 35% rate of positive findings in asymptomatic individuals, one must not rely solely on radiographic findings to determine the need for operative intervention. Therefore we rely more on clinical evaluation more than on MRI for decision making, although it may be considered to evaluate for other concomitant pathology or verification of peroneal disease in equivocal cases. In chronic ruptures, however, an MRI of the ankle is not likely to give one much information, but an MRI of the leg certainly will. If there is significant muscle atrophy, or fatty infiltration into both of the peroneal muscles, then it is not possible to use the remaining peroneal(s) in any way, since they have already undergone attritional changes of the muscle. Here a tendon graft, repairs of the tendon, and tenodesis of one peroneal to the other are not likely to work, and one has to rely on a tendon transfer. In cases of suspected subluxation and specifically intrasheath subluxation, the use ultrasound allows for dynamic examination of the peroneal tendons and confirmation of the diagnosis.
Management of Tendinitis
There are many causes of tendinitis or inflammatory-type symptoms related to tendon disease. If a patient presents after injury with pain behind the fibula or a fullness over the tendons associated with pain on resisted eversion, then either a tear or tenosynovitis is present. The cause may have been not a discrete injury, but rather repetitive episodes leading to the presenting clinical problem. If the injury is not acute, then the likelihood is that either inflammation, constriction, or infiltration of the tendons is present.
Another, less common cause of pain other than acute inflammation is chronic fatty infiltration of the tendon ( Fig. 23.1 ). Insertional peroneus brevis tendinitis can occur but is surprisingly not very common. Other rare causes of tendinitis include a peroneus quartus ( Fig. 23.2 ), and acute tenosynovitis from injury, generally acute hyperdorsiflexion ( Fig. 23.3 ). A far more common and typical clinical manifestation to be aware of is chronic pain distal to the tip of the fibula along the lateral calcaneus, where the tendons may be constricted as they pass in their separate sheaths along the peroneal tubercle. Although the tubercle may enlarge for no particular reason, enlargement is definitely more common in patients with heel varus or a cavus foot deformity. The pathomechanism in such cases may be chronic friction and pressure of the tendons on the tubercle, causing hypertrophy. This constriction will cause thinning and narrowing of the tendons. The tendon changes will in turn be worsened by the increased stress on the tendons incurred when the heel is in varus. Presence of focal pain along the lateral margin of the calcaneus in proximity to the peroneal tubercle warrants prompt exploration, because a tear of the tendon can be prevented by releasing the retinaculum and removing the peroneal tubercle. If additional procedures are not required simultaneously, the peroneal sheath can be released endoscopically without excising the tubercle, but constriction may recur. The longus and brevis tendons distal to the fibula have a separate sheath, and both tendons should be opened with small scissors. The split in the tendon is identified under the separate retinaculum, and the peroneal tubercle is debrided if it is seen to be enlarged. We use bone wax on the raw abraded surface under the peroneal tubercle once the repair is done ( Figs. 23.4 and 23.5 ; ). Another very common presentation is that in which an area of pain behind the fibula is worsened by passive dorsiflexion of the ankle. There is no associated subluxation, although the patient will report that it feels as if the tendon is going to pop forward. Instead of a tear of the tendon, a low-lying muscle of the peroneus brevis is present, causing symptoms by virtue of the volume effect in the retinaculum ( Figs. 23.6–23.8 ). As the foot dorsiflexes, the tendons are sucked into the fibula groove, and if the muscle volume is increased, pain will develop from impingement. This will cause tenosynovitis, and ultimately rupture if the attritional process continues untreated.
Repair of Isolated Tears of the Peroneus Longus and Peroneus Brevis Tendons
For repair of isolated tears of the peroneal longus and peroneal brevis tendons, an incision is made along the length of the posterolateral ankle extending along the course of the tendons behind the fibula. The proximal and distal extent of the incision is determined once the disease is identified after the retinaculum is opened. Preserving the extensor retinaculum, particularly at the margin of the distal fibula, is important. If the superior peroneal retinaculum is not adequately preserved, dislocation of the peroneal tendons with recurrent tendinopathy and tearing will occur as a result of repeated subluxation against the fibula. The tendon is generally seen to be split longitudinally with tears within the substance of the tendon and those that are posteriorly located. Longitudinal splitting is especially likely when the tear is associated with ankle instability.
The decision has to be made whether to repair the split or to excise a portion of the tendon. Considerations in this decision include the size, length, and extent of the split. The old adage of the 50% rule of a tendon being left intact is of historic interest only now, since efforts should be made to preserve the tendon where possible. Even if only 30%–40% of the tendon can be preserved, then the split portion may be excised longitudinally. The remaining tendon can be left intact (i.e., with the tendon open without a formal repair) ( Fig. 23.9 ); if further splits are encountered, the tendon is “tubed” with a running absorbable suture ( Fig. 23.10 ; ). If ankle instability and peroneal splits are associated with varus deformity of the heel, then all three components of the deformity can be addressed simultaneously using one extensile incision, through which the tendon repair, the ankle ligament reconstruction, and the lateral closing wedge and translational calcaneal osteotomy can be performed. If the tear of the brevis tendon is extensive, reaching both proximal and distal to the fibula, a portion of the tendon may still be excised or even used as part of a nonanatomic ankle ligament reconstruction ( Fig. 23.11 ). The latter procedure is very useful when there is marked ankle instability and an anatomic procedure (i.e., a Broström-type procedure cannot be performed). For these cases, in addition to the Broström procedure, any number of different types of nonanatomic procedures can be considered such as the Evans or the Chrisman-Snook procedure. In the patient who is a heavy athlete for whom the Broström-type repair will not be sufficient, the use of an Evans procedure or the use of novel suture-based internal fixation devices may be considered to augment the repair. Any chronic isolated tear of the peroneus brevis may be associated with a varus deformity of the calcaneus. This is particularly noticeable if the tear is unilateral and a varus deformity on one side only is noted. Alternatively, a cavovarus deformity is often associated with a tear of the peroneal tendons; however, here we are referring only to a chronic isolated rupture of the brevis tendon with associated heel varus. This is noted in a patient with chronic giving way of the lateral foot and a unilateral heel varus of 3 years’ duration ( Fig. 23.12 ).
