Posterior Impingement in the Ankle: “Can There Also Be a Muscular or Tendinous Entity?”

Fig. 37.1

(Courtesy Pau Golano) Transverse section at the level of the tibiofibular syndesmosis showing important structures susceptible to injury during ankle arthroscopy. 1 Lateral malleolus; 2 tibia; 3 anterior neurovascular bundle (deep peroneal nerve and anterior tibial artery and veins); 4 intermediate dorsal cutaneous nerve (lateral branch of the superficial peroneal nerve); 5 medial dorsal cutaneous nerve (medial branch of the superficial peroneal nerve); 6 posterior neurovascular bundle (posterior tibial nerve and posterior tibial artery and veins); 7 sural nerve and small saphenous vein; 8 saphenous nerve and great saphenous vein; 9 anterior peroneal artery; 10 posterior peroneal artery; 11 tibialis anterior tendon; 12 extensor hallucis longus tendon; 13 extensor digitorum longus tendon; 14 peroneus tertius muscle belly; 15 peroneus brevis longus; 16 peroneus brevis tendon; 17 tibialis posterior tendon; 18 flexor digitorum longus tendon; 19 flexor hallucis tendon (musculotendinous); 20 calcaneal and plantaris tendons

The main anatomical structure for the orientation and to determine the safe working area is the flexor hallucis longus tendon (FHL). Just medial to this tendon runs the posterior neurovascular bundle (tibial nerve and posterior tibial artery and veins). The posterior ankle arthroscopy should therefore routinely be performed lateral to the FHL tendon.

Proper positioning of the ankle and the hallux results in better visualization of the tendinous portion of the FHL muscle and avoids unnecessary resection of some of the muscle fibers that reach the lateral tendinous border in a semipenniform morphology. Plantar flexion of the ankle or hallux flexion facilitates visualization of the FHL tendon proximal to the lateral talar process.

The posterior ankle ligaments are also important for the orientation during the posterior ankle arthroscopy. These ligaments include the posterior talofibular ligament; the posterior intermalleolar ligament, also called the tibial slip in the arthroscopic literature; and the posterior tibiofibular ligament which is composed of a superficial and deep component or transverse ligament.

When the posterior ankle compartment is visualized arthroscopically, at first the location of the FHL tendon should be determined. Then the detailed anatomy of the posterior ankle can be identified more carefully.

The posterior talofibular ligament, component of the lateral collateral ligament, originates from the malleolar fossa, located on the medial surface of the lateral malleolus, coursing almost horizontally to insert in the posterolateral surface of the talus. This ligament is also an important reference in posterior ankle arthroscopy. Its location is important to know the site of the different working areas: subtalar and talocrural. The posterior subtalar recess is plantar to this ligament, and the talocrural joint is located dorsally (Burman 1931; Ogut et al. 2011; Golanó et al. 2006; van Dijk 2006; van Dijk et al. 2009; Ferkel and Scranton 1993).

37.4 Etiology

Posterior ankle impingement syndrome is a clinical pain syndrome that reflects the most common cause of posterior ankle pain, and it can be provoked by a forced hyperplantarflexion movement of the ankle (Andrews et al. 1985; Scholten et al. 2008; D’Hooghe and Kerkhoffs 2014). In the event of a soft tissue or bony posterior impingement of the ankle, plantar flexion induces a conflict between the posterior malleolus of the distal tibia on to the posterosuperior calcaneal bone. A bony prominent posterior processus of the ankle occurs in almost 7% of the sports population and can present itself as a hypertrophic posterior talar process or as an os trigonum. Although apparent posterior bony prominences caused by acute or repetitive overload (micro-) trauma can induce posterior ankle pain, it is not necessarily associated with the posterior ankle impingement syndrome.

Soft tissue impingement in the posterior ankle region can also occur and is frequently disregarded. It mainly is triggered by due hypertrophic FHL musculotendinous tissue, additional tendinous or doubled tendon structures, and posttraumatic scarification (van Dijk et al. 2009 ).

Since an acute forced hyperplantarflexion movement on the ankle or a repetitive overload induces the bony or soft-tissue conflict in the posteriorly located components of the ankle joint, we mainly see these lesions in a sports-specific population. The classical example of repetitive overload is seen in ballet dancers, where the forced plantar flexion during “en pointe” and “demi pointe” positioning induces repetitive impingement on the posteriorly located soft tissue components. Other types of sports related to the posterior ankle impingement syndrome include football, swimming, cycling, and any other sports in which the mechanism of injury is a repetitive forced plantar flexion or an acute setting (e.g., during a blocked kicking action in football). If the lesion occurs due to compression of the os trigonum between the distal tibia and calcaneal bone, it can lead to displacement of this os trigonum, disabling soft tissue inflammatory processes or even fractures of the processus posterior tali or distal tibia (van Dijk et al. 2009; Fig. 37.2).

Fig. 37.2

Posterior ankle impingement due to an “os trigonum syndrome” in a right ankle

37.5 Clinical and Diagnostic Features

Clinically, posterior impingement can be much more difficult to detect and diagnose when compared to other types of ankle impingement because the affected structures lie much deeper and can be mimicked by or coexist with other disease processes such as peroneal tendinopathy, retrocalcaneal bursitis, osteochondral lesions of the posterior talar dome, Achilles tendinopathy, flexor halluces longus tendinopathy or tenosynovitis, posterior tibial osteochondral injuries, tarsal tunnel compression, tarsal coalition, and Haglund’s deformity. Patients will complain of chronic deep posterior ankle pain that is worsened with push-off activities such as jumping. Physical examination includes palpation over the posterolateral process and the crunch test. Patients that suffer from posterior ankle impingement present with a posteriorly localized ankle pain during a (forced) plantar flexion movement.

The posterior ankle impingement test is a pathognomonic test to identify the clinical diagnosis of posterior ankle impingement. To have a positive test, the ankle is passively and quickly forced from neutral to hyperplantarflexion position, and during this movement, the patients encounter suddenly recognizable posteriorly located ankle pain. To increase compression on the posterolateral structures of the ankle, plantar flexion, external rotation, and eversion movements are considered during clinical testing.

Since the neurovascular structures and tendons are localized in the posteromedial region of the ankle, this area is not always easily palpated when compared to the clinical examination of the posterolateral part of the ankle (Golanó et al. 2006).

Diagnosis can be confirmed with abatement of pain following injection of an anesthetic into the posterolateral capsule of the tibiotalar joint. MRI is useful for more accurately identifying the anatomic site of abnormality, as well as revealing coexisting pathologies. Fortunately, rest is often adequate therapy regardless of whether the symptoms are acute or chronic. When nonoperative measures have failed, open or arthroscopic removal of the os can quickly return the footballer to play. Recent data has demonstrated the effectiveness of posterior ankle arthroscopy in the treatment of PAIS in the elite footballer, with return to training expected at an average of 5 weeks (D’Hooghe and Kerkhoffs 2014).

37.6 Accessory Muscles that Can Impinge on the Surrounding Musculotendinous Structures Around the Posterior Ankle

Multiple accessory, supernumerary, and anomalous muscles have been described in the radiologic, surgical, and anatomic literature. Accessory muscles of the ankle are typically asymptomatic, but can cause pain, compressive neuropathy, compartment syndrome, or rigid hindfoot deformities and can also mimic soft tissue tumors.

Magnetic resonance imaging (MRI) is the modality of choice in diagnosing accessory muscles, delineating their relationship to adjacent structures (e.g., impingement), and differentiating them from soft tissue tumors. Accessory muscles are isointense to skeletal muscle on all pulse sequences and can insert by fleshy muscular or tendinous insertions. Accessory muscles around the ankle include the flexor digitorum accessorius longus, the peroneocalcaneus internus, the accessory soleus, and the accessory peroneal muscles.

1.

Peroneus quartus muscle

While a few studies have associated various symptoms with the presence of a peroneus quartus muscle in the peroneal compartment of the leg, little is known of the clinical relevance of this muscle. Originally, several accessory muscles were distinguished in the peroneal compartment:

Peroneus quartus (PQ) (Otto)
Peroneus-calcaneus externum (Hecker)
Peroneus accessorius (White)
Peroneus digiti quinti (Testut)

This terminology has been simplified by summarizing all peroneal compartment variants under the definition of a peroneus quartus muscle as a muscle arising from the lower leg and inserting onto the lateral hind and midfoot. This also explains the variable insertion sites of the PQ muscle: