Acute Ankle Sprains – a clinical algorithm for a common injury

Leumann André, Schmidt Ina, Smirnov Evgeny, Loeffler Marius
Ortholeu Basel, Claragraben 78, 4058 Basel, http://www.ortholeu.ch

Introduction

Acute ankle Sprains (AAS) are considered to be one of the most frequent injuries in sports [1]. However, the entity of ankle sprains is very inhomogeneous. While some AAS may heal without medical care, others may deteriorate fast towards long-standing sequelae such as chronic ankle instability, osteochondral lesions and even posttraumatic osteoarthritis [2]. The current article aims at presenting a concept on how to diagnose and treat AAS.Acute Ankle Sprains (AAS) can be grouped in different types. The grouping may have an impact on diagnosis and treatment and thus, are explained more detailed in the following chapters. Grouping involves:

• Frequency of Sprains
• Injury Mechanism
• Injury Severity
• Ligamentous Injury and Instability
• Additional injuries – collateral damage
• Co-Factors

AAS typically present either in your outpatient clinic, on the emergency department or directly during a sport event where you are in charge. While analyzing the case, the main question is: Is it a simple AAS that can be treated conservatively?

What is a “simple” AAS?

A simple AAS is a first-time isolated injury to the lateral collateral ligaments (anterior fibulotalar ligament and fibulocalcanear ligament) without additional injuries. It can be treated conservatively with mechanical stabilization and functional training (see below).
Everything that is not typical for a simple AAS asks for further examination. Table 1 explains the three major factors: a) Trauma Mechanism; b) Ligament Injury; and C) Frequency of Sprains. If the “traffic lights” are green for all three factors, conservative treatment is the therapy of choice. If one of the factors lights orange or red, caution is advised, e.g. further imaging diagnostics and an adapted treatment.

Trauma Mechanism

A supination mechanism happens in 80 to 90% of ankle sprains, typically in the landing process while the foot is in plantarflexion and inversion. Here, little disturbance (e.g. by ground irregularities or a body contact in contact sports) is necessary to have the ankle joint roll into a supination leading to a lesion of the lateral capsulo-ligamentous complex. Therefrom, the anterior fibulotalar ligament and the fibulocalcanear ligament, both parts of the lateral joint capsule, are stretched, torn or ruptured.
The Trauma Mechanism has to be evaluated carefully. In a high-impact supination trauma, the affected limb creates an antagonistic effect to pull back leading to an eversion-
pronation trauma as a consequence. These three-dimensional injuries are often underrated and an injury to the medial ligaments is overseen.
Pronation injuries normally result in medial ligament injuries [3]. It requires high-impact as the deltoid ligament is 2-4 times stronger than den lateral ligaments. While injuries to the deep layer of the deltoid ligament (tibiotalar ligaments) are difficult to detect, injuries to the superficial layer (tibiocalcanear and tibionavicular ligaments) affect also the subtalar joint and lead to a higher degree of instability. If the Spring Ligament (plantar calcaneo-navicular ligament) is involved, uncontrolled abduction and loss of the medial arch structure is the sequela.
Most dangerous are rotation injuries in dorsiflexion (in Deutsch: in Dorsalextension) position of the ankle joint. External or internal rotation may lead to a syndesmotic injury [4]. External rotation may also lead to a spring ligament injury. Here, any instability should not be missed and surgical evaluation may be advised.

With clinical examination, it is difficult to separate a ligamentous stretch to a partial or even a complete rupture. Clinically, the joint is stable or unstable [5]. The instability might be graded in + unstable to +++ unstable. For lateral ligament injuries, this differentiation does not have an impact on treatment. But, it is important to distinguish between a stable and an unstable ankle joint. This is done through thorough clinical examination (Table 2). While MRI and ultrasound are basically static examinations, they do not give us any information on the stability of the ligaments. Table 2 names the most important clinical tests for evaluation of the ankle ligaments. Comparison to the contralateral ankle joint is advised in order to discriminate between traumatic instability and individual joint laxity. We recommend to include always examination of subtalar and Chopart joints.
Beside evaluating ligamentous instability, clinical examination also access insight to possible co-factors such as hindfoot alignment (cavovarus feet might be protective for medial ligament injures and planovalgus feet for lateral ligament injuries), joint mobility, circulation and perfusion, sensory or motoric impairments, and collateral damage.

Frequency of Sprains

First time AAS are experienced by the patient as severe injury leading to a large swelling and hematoma that evolves within a few hours [1]. But it does not necessarily mean that the injury leads to a complete loss of function. During competition, while the body is under tension and in an Adrenaline-flow, it is well possible, that the competition may be finished. This does not exclude a severe injury.
Many sport types are considered to be of high-risk for AAS with ratios of up to 90% of athletes being affected during their career. Among them are Basketball, Handball, Volleyball, Floorball, Soccer and various other ball-sport types but also Orienteering, Climbing, Wrestling, Ice Hockey and Ultimate Frisbee. So, it is not surprising that the most frequent type of ankle sprain is the Recurrent Ankle Sprain. Many athletes report a «career» of ankle sprains. A patient with recurrent ankle sprains reports typically, that each injury healed without sequelae. However, healing times after every injury may become longer showing that the ligaments get weaker or additional damage occurs. Thus, there might be the one injury to much [6].
Chronic ankle instability includes a subjective feeling of instability with recurrent episodes of giving-way, ongoing pain and frequent sprains (daily, weekly) without severe reactions of the ankle joint as the ligaments and capsule are already damaged [7].

Ligament Injury

Understanding of the normal anatomy of ankle joint ligaments is crucial. MRI anatomy is shown in Figure 1.

Additional injuries

Acute sprains and chronic instability may lead to additional injuries as shown in Table 3. Additional injuries require specific diagnostics and treatment not covered in this article.

Imaging

Further diagnostic beyond clinical examination basically is focused on imaging diagnostics. First line of imaging is the conventional x-ray. Here, the Ottawa Ankle Rules offers some help when to perform x-ray imaging. Personally, we recommend to use x-rays generously whenever there is a severe injury or a high impact.
Ottawa Ankle Rules describe to not perform x-ray imaging when in a severe ankle sprain: a) the foot is free of pain while weightbearing; b) following bony landmarks are free of pain on palpation: posterior rim of the Fibula, Base of the fifth metatarsal bone, navicular bone, posterior rim of the Tibia.
Whenever analysis according to Table 1 all traffic lights are « green » and clinical reasoning obvious, no further imaging is necessary. In doubts, or whenever one or more traffic lights are orange or red, further imaging is recommended, either by Ultrasound imaging in experienced hands, or by MRI. Aim of the analysis is to investigate injury to the medial deltoid ligament and syndesmosis. Thus, evaluating impact on treatment.
New imaging modalities in order to evaluate the syndesmosis have evolved. Weightbearing ct scans can be helpful as instability may be only obvious in the loaded situation (see Quiz question in this issue) [8].

Treatment

Treatment has to include two factors: a) proper ligament healing and restore mechanical stability; b) regain functional joint control and prevent recurrent injury [9].

Conservative Treatment of lateral ankle sprains

In conservative treatment, mechanical stability is achieved by bracing. Functional joint control is achieved by proprioceptive and postural training.
Ligament healing is separated in inflammation phase
(0-14 days after trauma), proliferation phase (2-21 days), remodeling phase (21-60 days) and maturation phase (40-500 days). On the microscopic level, in the proliferation phase scarring of the ligament happens, fibrocytes produce unorganized collagen fibers. In the remodeling phase these unorganized collagen fibers become organized in its orientation and in its function. Full strength of ligaments is achieved after two months. In the maturation phase, final biomechanical functions such as strain-function and elasticity are restored. Thus, mechanical protection with an orthosis is needed for at least 6 to 8 weeks. During this time, increased strain on the healing ligaments may lead to elongated ligaments and thus, creating instability. Knowing that, it is important to wear the brace/orthosis also during the night for at least 4 weeks [6].
The trauma mechanism does not only lead to a mechanical damage of ligaments, but it does also impair the functional or postural joint control [10]. A functionally stable joint is important to restore a functionally loadable joint, to compensate possible ligamentous weakness and is the major factor to prevent recurrence [11]. E.g. in a large prospective study on more than 1000 volleyball players, functional ankle training significantly reduced ankle sprain recurrence [12].
A functional weakness or instability is established within 6 weeks [13]. This is the main reason to start with physiotherapy directly after the injury and to work with active, proprioceptive and sensorimotor training until full function and full stability is achieved. This is also the reason why casting a ligamentous ankle joint injury in sports active patients or athletes is not adequate anymore.
While there are studies for non-demanding, rather sedentary patients in low-budget health systems like England that claim that physiotherapy is not necessary, there are enough randomized trials that point out the importance of active physiotherapy in athletes in order to end up with a fully stable joint in sports, fast recovery and reduced recurrence [14].
Return to Sport is possible within weeks based on pain and swelling. Not yet fully healed ligaments might be protected by bracing and or taping. Bracing or taping is also recommended during sports activities for at least 6 months. In high-risk sport types, life-long preventive bracing or taping might be an option. Also in these cases, regular sensorimotor training should be part of the training regime [15].
In patients where the medial deltoid ligament complex and or the syndesmosis is included in the injury patterns, the evaluation of an instability is essential. Are these ligaments injured but clinically stable, still conservative treatment is possible. Then, partial weightbearing and a more consequent immobilization is required, e.g. with a Vacoped or a Aircast Walker long, for two up to 6 weeks post trauma. Here, frequent follow-up examinations are advised in order to not miss a later failure of the ligaments.
In patients with an unstable syndesmosis or an unstable medial ligament complex (deltoid ligament and or Spring ligament), surgical reconstruction is the choice of treatment. Both ligament complexes are crucial for the joint stability. They have an excellent healing potential when treated early and adequate but have a poor outcome when they became chronically unstable [16]. Then, much larger reconstructions including even osteotomies (e.g. calcaneal osteotomy or supramalleolar osteotomy) or tendon transfer surgeries are needed to restore a stable joint. Hence, a full return to sports participations without limitations is difficult to achieve.

Conclusion

This article offers a clinical algorithm on decision making and treatment of acute ankle sprains. Key factors are analyzing trauma mechanism, sprain frequency and ligament injury. Therefore, a thorough clinical examination is important. Additional diagnostic imaging modalities may be required.
The primary treatment concept is conservative, but in more severe injuries including medial and syndesmotic ligaments may require longer immobilization and partial weightbearing. In case of medial ankle instability or syndesmosis instability, surgical reconstruction have to be considered.

Corresponding author

PD Dr. med. Dr. phil. André Leumann
Ortholeu Basel
Claragraben 78, 4058 Basel
info@ortholeu.ch
http://www.ortholeu.ch

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