Peroneal tendon subluxation

Definition/Description

Peroneal tendon subluxation, or dislocation, is a disorder involving elongation, tearing, or avulsion of the superior retinaculum of the fibula [1]. An intact superior retinaculum (SPR) may also result in subluxation of the tendon (intrathecal subluxation) [2].

Clinically Relevant Anatomy

The peroneus brevis and peroneus longus are contained in the posterior ankle groove of the fibula. The depth of the furrow is variable and has been noted to be absent or raised in some [3]. The tendon is stabilized by the superior retinaculum of the fibula. SPRs are formed by superficial thickening aponeurosis. Occasionally a small fibrous ridge is seen originating from the distal fibula near the origin of the SPR and adding depth to the fibular groove. The distal fibula is the subfibula retinaculum, which covers the tendon about 2 to 3 cm from the tip of the fibula Fibula [4].

Epidemiology /Etiology

The most common mechanism is ankle dorsiflexion associated with rapid and intense contraction of the peroneal tendon and rearfoot eversion [5]. Subluxation or dislocation of the peroneus longus and brevis tendons from the posterior groove of the lateral malleolus. This is the result of tearing SPR avulsion or marked laxity. Some patients have a more chronic presentation and cannot recall the traumatic event. Congenital factors have also been reported, such as the groove or ridges that help deepen the groove may be too shallow or even absent, or the SPR may be too loose [5].

Peroneal tendon subluxation is common in skiing but has also been reported in other sports such as gymnastics, ice skating, and rugby [1][6][7].

Fibular subluxation accounts for 0.3-0.5% of traumatic ankle injuries [7].

Characteristics/Clinical Presentation

Acute fibular subluxation is divided into three grades[8][3][9]

Grade I: The retinaculum confluent with the fibular periosteum is detached from the fibula, resulting in dislocation of the tendon.

Grade II: The fibrocartilage ridge and SPR are avulsed from the posterior aspect of the fibula.

Grade III: bony avulsion of the posterolateral fibula, containing a cartilaginous border and a bone fragment, allowing the tendon to slide subperiosteally.

Grade IV: SPR elevated from the calcaneus

Patients with high cavus may be prone to fibular subluxation and lateral ankle instability [7].

Clinical Presentation[1][7]:

• Popping or snapping sensation on the outer edge of the ankle
• Forceful pop in traumatic injuries
• The tendon slides out of place along the lower end of the fibula
• Painful swelling or tenderness under/behind the outer ankle
• Painful resisted ankle eversion
• Ankle instability, especially on uneven surfaces
• History of chronic posterior ankle pain and/or recurrent ankle sprains in patients with chronic subluxation

Differential Diagnosis

• Ankle Sprain
• Peroneal Tendinopathy

Examination

Acute fibular subluxation is often difficult to recognize clinically. Compared with the case of ankle sprains, edematous ecchymosis and tender points are often present in the same distribution, making it difficult to diagnose [5].

Because of the dorsiflexion mechanism of the injury, a crush test can help determine whether there is a syndesmotic component [7].

Subluxation of the peroneal tendon can be reproduced by repeated dorsiflexion and plantar flexion of the patient while the examiner provides a force against ankle valgus [7]. A negative test does not rule out a subluxation injury.

In chronic cases, patients often complain of pain from the capstan mechanism, and the dislocation can usually be reproduced by active dorsiflexion-valgus of the foot [5]. In most cases, the peroneal tendon snap around the posterior border of the lateral malleolus can be palpated, and even visualized by the examiner. These clinical findings can be enhanced by applying slight resistance to dorsiflexion-valgus.

Acute injuries should be screened for fractures using the Ottawa Ankle Rules to determine the need for referral for radiography to assess for avulsions [7].

MRI can show the static anatomy of the peroneal tendon. Ultrasound is becoming a more popular diagnostic imaging tool because it can evaluate the peroneal tendon in a dynamic environment. Ultrasonography was 94% accurate, 100% sensitive, and 90% specific, while MRI was 66% accurate It has a sensitivity of 23% and a specificity of 100% [7].

Management

In infants and newborns, conservative treatment of subluxed peroneal tendons is routine, with a high rate of spontaneous resolution [5] [10].

When considering acute or chronic injuries, treatment in adults can be divided into nonsurgical and operative [5]. When acute subluxation is diagnosed, patients may be considered for nonoperative management [8][3]. If conservative treatment fails or chronic subluxation is present Surgical treatment may be required [7][8]. Early treatment is critical, as tendons that continue to sublux (shift out of position) are more likely to tear or rupture [11].

Conservative

In particular non-surgical treatment is indicated for grade I and possibly grade III injuries, depending on the degree of displacement of cortical fragments [8]. The risk of conservative treatment is small, but the failure rate is also high [5].

Nonsurgical treatment consists of immobilization with a non-weightbearing cast for 2–6 weeks [8]. This conservative management aims to reattach the SPR to the posterolateral aspect of the fibula [5].

A conservative attempt can also include adhesive ligating with pads to limit subluxation J-shaped pads anchored anteriorly to the fibula and wrapped laterally and posteriorly to hold the tendon in place and without weight bearing for 2-6 weeks. If the foot remains relatively stable and The tape restricts the movement of the tendon – the formation of scar tissue may allow the tendon to be controlled without surgery [12]. Exercises included in post-immobilization rehabilitation include proprioceptive training and range-of-motion exercises.

Physical therapy management

Ideally, physiotherapy management begins with asking the patient not to bear weight for a period of 2 weeks. After this, the patient is asked to wear the walking boot for the next 4 weeks.

Then start with active range of motion, work on proprioception, and move on to strength training. Strength training can include resistance band programs and proprioceptive neuromuscular facilitation. [13]

Wrapping around the lateral malleolus has also been found to successfully prevent recurrent subluxations. [14] After increasing strength, aerobic exercises such as swimming and cycling were also included in the program.

After fully mastering functional training, patients can carry out specific sports training. Athletes usually return to competition after about 3-4 months. [15]

Surgical

Treatment of chronic lesions is less controversial, as surgical repair of peroneal tendon subluxation provides good results in most cases [5].

Surgical options[8][16]:

• Bone block procedure
• Rewired SPR through local tissue enhancement
• Enhanced SPR through local tissue transfer
• Alteration of the tendon behind the calcaneofibular ligament [17]
• Groove-deepening procedures

The surgical approach may vary depending on the extent of the injury [4].

Physical therapy after surgery

Other than the movement precautions, rehabilitation can proceed as for the chronic ankle sprain. However, postoperative rehabilitation is likely to take more time to fully restore movement strength and function[16].

Postoperatively, the ankle is maintained for 4 weeks on a non-weight-bearing splint followed by 2 weeks in a weight-bearing machine. During immobilization cardiovascular conditioning is performed along with proximal muscle strengthening[16].

The first few exercise treatments are designed to help control pain and inflammation from the surgery. Ice and electrical stimulation can be used. The practitioner may also use massage and other manual therapy to ease muscle spasms and pain. Collection of soft tissue around the lesion the area can be used to enhance soft tissue mobility[12].

Therapy is also used to help improve ankle range of motion through gradual resistance and ROM exercises with less stress on the area[16]. Active and resistant dorsiflexion and eversion are prevented during the initial preparation phase to reduce the stress on the SPR (approximately 6). up to 8 weeks[12].

Talar mobilization exercises and active dorsiflexion and eversion begin when the patient is able to bear weight without pain[12].The development of resisted strengthening proprioception and agility exercises are initiated when a patient is able to bear weight without pain and without a brace. If energy is proprioception improves if the patient can be improved by plyometric and functional activities allowing him to return to competition[12].