DERECHOS HUMANOS

U. Szeimies

Definition

Disorders of the peroneus longus and brevis tendons occurring from the distal lower leg to the tendon insertions are classified by the location of the tendon pathology. Peroneal split syndro-me and peroneal tendon subluxation are special disorders that are discussed below under separate headings.

Symptoms

●Chronic pain about the lateral malleolus, sometimes with pal-pable thickening along the malleolus

●Possible painful click or snap on eversion of the foot

●Positive peroneal compression test on physical examination (compression of the peroneus longus tendon against the peroneus brevis tendon)

●Partial tears, which are more common in trauma cases, com-plete tears less common

●Complete rupture may occur in patients with pes cavus deformities

Predisposing Factors

●Overuse

●Repetitive trauma with incomplete healing

●Acute injuries

●Chronic irritation in sports involving frequent direction changes (tennis, ball sports such as soccer, handball, and bas-ketball)

●Anatomic factors (accessory muscle, accessory bone, friction against the calcaneus)

●Hindfoot varus

●Chronic lateral instability

Anatomy and Pathology

The peroneus longus and brevis tendons (lateral ankle stabiliz-ers) have sites of predilection for painful overload injuries in their course from the lateral malleolus to the midfoot. It is im-portant, therefore, to have a precise knowledge of their anato-my and function.

Anatomy

Function of the peroneal tendons

Both tendons contribute to plantar flexion of the foot. As a powerful pronator, the peroneus longus muscle actively sta-bilizes the plantar vault, giving particular support to the transverse arch. The peroneal muscles are innervated by the superficial peroneal nerve (L5 and S1). Paralysis of the pero-neal muscles causes a weakening of pronation, allowing the flexors to pull the foot into a supinated position (hindfoot varus) that is initially flexible but gradually progresses over time to a fixed deformity. Concomitant extensor paralysis leads to pes equinovarus.

Peroneal tendon anatomy (▶Fig. 3.86).

Both tendons are held in place by the superior peroneal retinac-ulum as they pass through a bony groove behind the lateral

Fig. 3.86 Anatomy and relationships of the peroneal tendons (source: Dihlmann and Stäbler 2010).

Fib. = fibula

1 Superior extensor retinaculum

2 Inferior extensor retinaculum; structures 1 and 2 are bands that hold the extensor tendons (tibialis anterior, extensor digitorum longus, ex-tensor hallucis longus) in place

3 Superior peroneal retinaculum

4 Inferior peroneal retinaculum; structures 3 and 4 are bands that hold the two peroneal muscles (peroneus longus and brevis) in place 5 Extensor hallucis longus tendon sheath

6 Retrocalcaneal bursa 7 Peroneus brevis tendon sheath 8 Peroneus longus tendon sheath

9 Short common synovial sheath for the peroneus longus and brevis tendons (starts just proximal to the superior peroneal retinaculum and extends to the cuboid)

10 Peroneus tertius tendon sheath 11 Extensor digitorum longus tendon sheath 12 Subcutaneous bursa of the lateral malleolus

The tibialis anterior tendon and its sheath (not pictured) run medial to structure 5, next to the anterior tibial margin

malleolus; they are bound to the lateral aspect of the calcaneus by the inferior peroneal retinaculum. At this level the tendons share a common fibro-osseous sheath in which they are placed not side by side but one above the other, the peroneus longus being superficial to the peroneus brevis. The common tendon sheath bifurcates at the level of the peroneal tubercle, giving rise to separate sheaths. The peroneus brevis tendon inserts on the base of the fifth metatarsal. The peroneus longus tendon runs around the cuboid tuberosity at the inferior edge of the cu-boid; the tuberosity creates a fulcrum for redirecting the tendon along the pedal arch through a fibro-osseous tunnel to the me-dial side of the foot. Finally, the peroneus longus tendon inserts by multiple slips on the medial cuneiform, the base of the first metatarsal, and occasionally the base of the second metatarsal.

Pathology

●Distal tip of the fibula: The direction change at the tip of the fibula can cause mechanical irritation that may lead to a per-oneal split syndrome.

●Peroneal retinaculum: Subluxation or dislocation of the pero-neal tendons may result from injuries relating to an old ankle sprain.

●Peroneal tubercle: A prominent tubercle on the lateral calca-neus may cause increased frictional forces with mechanical irritation and peritendinitis or tendinosis.

●Os peroneum: This is a sesamoid bone in the peroneus longus tendon, located laterally on the plantar side of the cuboid.

Possible disorders include fractures, osteonecrosis, and le-sions of the tendon attachments.

●Cuboid tunnel: The peroneus longus tendon is redirected me-dially in this fibro-osseous tunnel. Tightness in the tunnel may cause an entrapment syndrome with tendon degenera-tion and osseous stenosis. Longitudinal tears have been de-scribed. The direction change and passage through the tunnel lead to increased biomechanical loads.

●Insertional tendinopathy:

○Peroneus longus tendon: medial cuneiform and base of the first metatarsal. Activation at the fibro-osseous junction, es-pecially at the lateral base of the first metatarsal, may lead to tendon thickening, fibrovascular reaction, subchondral cysts at the metatarsal base, ganglion cysts, associated bone marrow edema, fibro-osteitis, degenerative tendon vascu-larity, and partial tearing.

○Peroneus brevis tendon: insertion on the tuberosity of the fifth metatarsal.

○Another normal variant: presence of an accessory muscle, the peroneus quartus.

●Complete rupture: Acute ruptures of the peroneus brevis ten-don most commonly occur at the level of the distal tip of the fibula or peroneal tubercle. The entrance to the cuboid tunnel is a site of predilection for tears of the peroneus longus ten-don. Ruptures of both tendons are rare and are mainly found in association with severe hindfoot varus deformities.

Imaging

Radiographs

Radiographic imaging is helpful for identifying bony structures that can cause tendon degeneration (prominent peroneal

tubercle, os peroneum, ossification at the distal tip of the fibu-la). Weight-bearing views of the foot are obtained in three planes to evaluate foot position (pes cavovarus deformity). A Saltzman view is obtained to evaluate hindfoot alignment.

Weight-bearing views of the ankle joint in two planes can ex-clude a supramalleolar deformity.

Ultrasound

Ultrasound can display the peroneal tendons in longitudinal and transverse sections by scanning from the lower third of the tibia distally around the lateral malleolus to the fifth metatarsal (peroneus brevis muscle). A short linear-array transducer will yield better results (7.5–15 MHz). A stand-off should be used if coupling is poor. In cases of suspected dislocation, provocative testing should be done under monitor control to allow dynamic assessment of stability. A degenerative tear produces an “aspar-agus tip” sign.

MRI

Interpretation Checklist

●Describe the location and extent of tendon pathology

●Evaluate the cause (e.g., os peroneum, old retinacular injury)

●Evaluate tendon quality (intratendinous mucoid degenera-tion, partial tear)

●Evaluate bony structures (adjacent bone reaction)

●Look for secondary changes (joint overload, bony stress ede-ma, other tendon pathology)

Examination Technique

●Standard tendon protocol: prone position, high-resolution multi-channel coil

●Sequences:

○Coronal and sagittal PD-weighted fat-sat

○Coronal T1-weighted

○Axial T2-weighted (angled to joint plane)

○T1-weighted fat-sat after contrast administration, axial obli-que (angled to tendon plane), and sagittal

MRI Findings (▶see Figs. 3.87–3.93)

●Early signs: peritendinitis with increased enhancement along the tendon sheath (more frequently involves the peroneus brevis at the lateral malleolus than the peroneus longus)

●Tendinosis: thickening of the tendon, possible degenerative tendon vascularity with increased intratendinous enhance-ment, sometimes localized to one point; enhancing zone of advanced mucoid degeneration within the tendon

●Longitudinal partial tear, usually affecting the peroneus brevis tendon at the lateral malleolus

●Accompanying bone irritation with bone marrow edema in the lateral malleolus, lateral calcaneus, and cuboid

●Insertional tendinopathy with increased enhancement at the fibro-osseous junction on the fifth metatarsal, medial cunei-form or base of the first metatarsal

●Possible activation of the os peroneum (bipartite ossicles and fractures are also described)

●With a complete rupture: empty, enhancing fluid-filled ten-don sheath, frayed tenten-don ends, possible reaction of tenten-don ends

Imaging Recommendation

Modality of choice: MRI to evaluate the extent of pathology, for localization, for determining the cause, and evaluating associ-ated changes.

Differential Diagnosis

●Anterolateral impingement

●Ankle instability with synovitis

●Fractures involving the lateral ankle joint or pedal border

Treatment

●Rupture of the peroneus brevis tendon: surgical reconstruction

●Rupture of the peroneus longus tendon: conservative treat-ment or debridetreat-ment and tenodesis

●Ruptures of both tendons: surgical reconstruction

●Tendon transfer of peroneus longus to peroneus brevis, if required

Prognosis, Complications

Possible complications:

●Complete rupture due to chronic tendinosis

●Chronic pain syndrome

Peroneal Tendon Subluxation or Dislocation Definition

Peroneal tendon subluxation or dislocation is an acute (trau-matic) or chronic displacement of one or both peroneal tendons from their anatomic position along the retromalleolar groove behind the lateral malleolus.

Symptoms

●Pain posterior to the lateral malleolus

●Tendon snap provoked by dorsiflexion and eversion

●Possible painful swelling Fig. 3.87 Peritendinitis due to chronic mechanical irritation of the

peroneal tendons at the distal tip of the fibula. Axial oblique T1-weighted fat-sat image after contrast administration shows increased enhancement in the common tendon sheath of the peroneus longus and brevis tendons with an incipient partial tear in the peroneus brevis at the tip of the fibula.

Fig. 3.88 a, b Os peroneum. Activated sesamoid bone in the peroneus longus tendon on MRI.

a Oblique sagittal PD-weighted fat-sat image shows two hypointense segments from the peroneus longus tendon at the level of the cal-caneocuboid joint. A small, intratendinous bony structure is visible.

b Oblique axial T1-weighted fat-sat image after contrast administration. The marked activation process is visualized after IV contrast adminis-tration.

Predisposing Factors

●Acute injury

●Congenital shallow retromalleolar groove

●Old lateral ankle sprain with injury to the peroneal tendon sheath and retinaculum leading to functional impairment and instability

●Lateral calcaneal fracture with injury to the superior peroneal retinaculum

! Note

There may be an associated injury of the calcaneofibular ligament.

Fig. 3.89 Peroneal tubercle. A prominent peroneal tubercle on the lateral calcaneus. Axial oblique T1-weighted fat-sat MRI after contrast administration shows activated bony excrescences on the peroneal tubercle with associated mechanical irritation and peritendinitis, predominantly affecting the peroneus longus tendon.

Fig. 3.90 a, b Retinaculum. Activation of the peroneal retinaculum in a 47-year-old muscular, athletically active man following multiple super-ficial injuries, the most recent occurring 4 weeks ago. The patient had a known history of peroneal tendon subluxation for years. He was investigated now for lateral ankle pain.

a Sagittal T1-weighted image after contrast ad-ministration. Both images (a, b) show an intense soft-tissue reaction that is most pronounced in the course of the peroneal retinaculum and cal-caneofibular ligament.

b Another sagittal T1-weighted image after con-trast administration.

Fig. 3.91 Cuboid tunnel. Peritendinitis at the entrance to the cuboid tunnel. Sagittal T1-weighted fat-sat image after contrast administra-tion shows activaadministra-tion of the peroneus longus tendon at the level where it turns sharply into the fibro-osseous tunnel at the cuboid bone.

Anatomy and Pathology

Redirection of the tendon at the lateral malleolus from a cranio-caudal to anterior distal course makes it more susceptible to

traumatic subluxation in response to dorsiflexion and forcible eversion of the foot.

A chronic peroneal tendon dislocation is present when an in-jury of the superior retinaculum allows the tendon to slip out of its groove and dislocate forward over the lateral malleolus. A painful, recurrent snapping takes place over the lateral malleo-lus in response to dorsiflexion and pronation. A shallow fibular groove can predispose to peroneal tendon dislocation, with stripping of the proximal retinaculum and periosteum from the lateral malleolus; isolated tearing of the retinaculum is rare.

The stripped periosteum creates a “false pouch” over the lateral malleolus into which the tendon is displaced.

A special form is intratendinous subluxation with an intact retinaculum and a normal anatomic course in the retromalleo-lar groove. This form occurs when the peroneus longus tendon slips beneath the peroneus brevis.

Imaging

Radiographs

Radiography is not indicated as an initial study. When neces-sary, it can be used to exclude a bony injury and to identify bo-ny structures as the cause of an abnormal retromalleolar groove. It permits differentiation from tendon degeneration (osteophytes).

Ultrasound

A transverse scan is performed behind the lateral malleolus.

Dynamic ultrasound imaging can be used to evaluate tendon dislocation and intratendinous subluxation. Ultrasonography is better than MRI for documenting tendon instability.

MRI

Interpretation Checklist

The retromalleolar groove can be evaluated by MRI:

●Chronic subluxation due to a shallow groove Fig. 3.92 Insertional tendinopathy of the peroneus longus tendon.

Axial oblique T1-weighted fat-sat image after contrast administration documents peritendinitis and enhancing tendon fibers at the fibro-osseous junction on the lateral base of the first metatarsal.

Fig. 3.93 a, b Peroneal tendon rupture.

a Sagittal PD-weighted fat-sat image shows a complete rupture of the peroneus longus tendon with mucoid degeneration and retraction of the tendon end. The peroneus brevis tendon appears intact.

b Axial oblique T1-weighted fat-sat image after contrast administration shows an absence of nor-mal tendon structure posterior to the peroneus brevis. The tendon sheath is occupied by fibro-vascular reactive tissue and degenerative residual fiber stumps (arrow).

●Quality of the superior retinaculum

●Signs of activation

●Quality of the peroneal tendons

●Extent of peritendinitis and tendinosis

●Bone marrow edema at the fibular border

●Possible ganglion cysts, osteophytes

Examination Technique

●Standard tendon protocol: prone position, high-resolution multi-channel coil

●Sequences:

○Sagittal and coronal PD-weighted fat-sat

○Coronal T1-weighted

○Axial T2-weighted (angled to joint plane)

○T1-weighted fat-sat after contrast administration, axial obli-que (angled to tendon plane) and sagittal

MRI Findings (▶Fig. 3.94)

●Peroneal tendons do not follow their normal retromalleolar course but run over or anterior to the fibula.

●With an acute dislocation: hemorrhage along the retinacu-lum, possible rupture of the calcaneofibular ligament, possi-ble fracture of the lateral calcaneal border.

●With a chronic dislocation or subluxation: fibrovascular enhancement around the peroneal tendons including the ret-inaculum and calcaneofibular ligament.

●Possible bone marrow edema and osteophytes along the tip of the fibula.

●The tendons themselves are usually intact; tendinosis devel-ops only with long-standing subluxation.

! Note

The tendons may reduce spontaneously, creating problems of MRI interpretation. A dynamic ultrasound study has definite ad-vantages in cases of this kind.

Imaging Recommendation

Modalities of choice: ultrasound for evaluating tendon stability and for dynamic examination. MRI is advantageous for detailed

visualization of the peroneal tendons and establishing the cause of the dislocation.

Differential Diagnosis

●Acute lateral ankle sprain

●Chronic instability

●Lateral impingement

●Chronic synovitis

●Early osteoarthritis

Treatment

Conservative treatment with 6 weeks’ immobilization should be considered only for a fresh, spontaneously reducing injury.

The redislocation rate with conservative therapy is up to 50%.

The treatment of choice is surgical and involves deepening the tendon groove and/or reconstructing the retinaculum.

Prognosis, Complications

The prognosis with surgical intervention is good. Chronic dislo-cation carries a risk of tendon rupture.

Peroneal Split Syndrome Definition

Peroneal split syndrome refers to longitudinal tearing or split-ting of the peroneus brevis tendon in the malleolar region with migration of the peroneus longus tendon into the tear.

Symptoms

●Chronic lateral ankle pain

●Painful swelling

●Tenderness to pressure

Predisposing Factors

●Overuse

●Repetitive injuries

●Torsional trauma with injury to the calcaneofibular ligament Fig. 3.94 a, b Acute traumatic dislocation of the peroneal tendons.

a Coronal PD-weighted fat-sat image (coronal section through the lateral malleolus) shows rup-ture of the retinaculum with anterior dislocation of the peroneus longus and brevis tendons. The peroneus longus tendon courses over the fibula.

b Axial PD-weighted fat-sat image shows the per-oneal tendons dislocated from the retromalleolar groove (arrow) with conspicuous hemorrhage along the retinaculum and a patchy hematoma in the soft tissues of the ankle joint.

●Shallow retromalleolar groove

●Injury to the superior retinaculum with increased tendon play and friction

●Peroneus quartus muscle

●Low-lying short peroneal muscle belly

Anatomy and Pathology

At the distal tip of the fibula, the peroneus longus tendon lies deep to the peroneus brevis tendon and is compressed against the short tendon with increasing dorsiflexion. This may cause fraying and longitudinal splitting of the peroneus brevis ten-don, which partially envelops the peroneus longus tendon in a U-shaped configuration. There are also asymptomatic normal variants with a short duplicated segment of the peroneus brevis tendon.

Imaging

Radiographs

Radiographic imaging is performed to exclude associated bony injuries. The ankle is imaged in two planes. Stress radiographs may be obtained in patients with suspected chronic instability of the talocrural or subtalar joint.

Ultrasound

Ultrasound can demonstrate fluid and synovitis in the peroneal tendon sheath.

MRI

Interpretation Checklist

●Extent of tendon degeneration and activated inflammation

●Evaluate anatomy (retromalleolar groove, accessory muscle, ossifications)

●Evaluate nearby structures (superior retinaculum and calca-neofibular ligament)

●Bone marrow edema in the fibula

●Secondary changes in adjacent joints

Examination Technique

●Standard tendon protocol: prone position, high-resolution multi-channel coil

●Sequences:

○Sagittal and coronal PD-weighted fat-sat

○Coronal T1-weighted

○Axial T2-weighted (angled to joint plane)

○T1-weighted fat-sat after contrast administration, axial obli-que (angled to tendon plane) and sagittal

MRI Findings (▶Fig. 3.95)

●Differentiation from the normal variant of a bipartite pero-neus brevis tendon by contrast administration

●Chronic inflammation with tendinosis: increased enhance-ment along the tendon sheath

●Splitting of the peroneus brevis tendon into two tendons (at the center is the peroneus longus tendon, best demonstrated in axial oblique T1-weighted fat-sat images after contrast ad-ministration)

●Possible degenerative intratendinous changes, even in the peroneus longus tendon (signal inhomogeneities, mucoid de-generation, increased vascularity in the tendon with associ-ated enhancement)

●With chronic instability: extensive, enhancing irritative proc-ess that includes the superior retinaculum and fluid collec-tion, which show a blurry, ill-defined structure

Imaging Recommendation

Modality of choice: MRI to define the extent of the tear and per-haps identify its precipitating causes and secondary effects.

Differential Diagnosis

●Rheumatoid arthritis

●Chronic ankle instability

Fig. 3.95 a, b Peroneal split syndrome.

a Axial oblique T1-weighted fat-sat image after contrast administration shows a peroneal split syndrome with a long longitudinal tear of the left peroneus brevis tendon and signs of peritendini-tis. The peroneus longus tendon is intact. Note the U-shaped arrangement of the torn peroneus brevis fibers partially enveloping the peroneus longus tendon.

b Sagittal T1-weighted fat-sat image after con-trast administration. The sagittal slice displays three subtendons formed by longitudinal split-ting of the peroneus brevis tendon.

Treatment

●Acute injury: conservative treatment with 6 weeks’ immobili-zation in a walker boot is an option

●Chronic lesion: surgical treatment of the tear by intratendi-nous side-to-side suture repair

Prognosis, Complications

There is a risk of complete rupture of the peroneus brevis tendon.

3.2.8 Posterior Tibial Tendon

In document Residentes en el extranjero (página 91-94)