Keywords

FormalPara Top 10 Evidence-Based References
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    Doherty C, Bleakley C, Delahunt E, Holden S (2017) Treatment and prevention of acute and recurrent ankle sprain: an overview of systematic reviews with meta-analysis. Br J Sports Med 51:113–125

  2. 2.

    Hunt KJ, Fuld RS, Sutphin BS, Pereira H, D’Hooghe P (2017) Return to sport following lateral ankle ligament repair is under-reported: a systematic review. J ISAKOS Joint Disorders Orthop Sports Med EPub ahed of Print. https://doi.org/10.1136/jisakos-2016-000064

  3. 3.

    Hélder Pereira, Gwen Vuurberg,f Nuno Gomes, Joaquim Miguel Oliveira, Pedro L. Ripoll, Rui Luís Reis, João Espregueira-Mendes, C. Niek van Dijk (2016) Arthroscopic repair of ankle instability with all-soft knotless anchors. Arthrosc Tech 5(1):e99–e107. Published online 2016 Feb 1. https://doi.org/10.1016/j.eats.2015.10.010

  4. 4.

    Guillo S, Takao M, Calder J, Karlson J, Michels F, Bauer T, Ankle Instability Group (2016) Arthroscopic anatomical reconstruction of the lateral ankle ligaments. Knee Surg Sports Traumatol Arthrosc 24(4):998–1002. https://doi.org/10.1007/s00167-015-3789-z. Epub 2015 Sep 25. PMID: 26408309

  5. 5.

    Michels F, Pereira H, Calder J, Matricali G, Glazebrook M, Guillo S, Karlsson J, ESSKA-AFAS Ankle Instability Group (2017) Searching for consensus in the approach to patients with chronic lateral ankle instability: ask the expert. Knee Surg Sports Traumatol Arthrosc. https://doi.org/10.1007/s00167-017-4556-0. [Epub ahead of print]

  6. 6.

    Jari Dahmen, Kaj TA Lambers, Mikel L Reilingh, Christiaan JA van Bergen, Sjoerd AS Stufkens, Gino MMJ Kerkhoffs (2017) No superior treatment for primary osteochondral defects of the talus. Knee Surg Sports Traumatol Arthrosc. https://doi.org/10.1007/s00167-017-4616-5. [Epub ahead of print]

  7. 7.

    Zengerink M, Struijs PAA, Tol JL et al (2010) Treatment of osteochondral lesions of the talus: a systematic review. Knee Surg Sports Traumatol Arthrosc 18:238. https://doi.org/10.1007/s00167-009-0942-6

  8. 8.

    VIDEO: Athletic Injuries of the Ankle - Anterior ankle impingement ESSKA Academy. Pereira H. Jul 14, 2014; 58936 Topic: Ankle: https://academy.esska.org/esska/2014/dvds/58936/helder.pereira.athletic.injuries.of.the.ankle.-.anterior.ankle.impingement.html?f=topic=7059*media=1

  9. 9.

    van Dijk CN1, van Bergen C (2008) Advancements in ankle arthroscopy J Am Acad Orthop Surg 16(11):635–46.

  10. 10.

    Ross KA, Murawski CD, Smyth NA, Zwiers R, Wiegerinck JI, van Bergen CJ, Dijk CN, Kennedy JG (2017) Current concepts review: arthroscopic treatment of anterior ankle impingement. Foot Ankle Surg 23(1):1–8.

FormalPara Fact Box 1 – Ankle Injury Epidemiology

  • Inversion ankle sprain most frequent mechanisms: often during landing on the lateral border of the foot, or if the foot gets locked on the ground, while the body continues to turn.

  • Isolated lesions of the ATFL occur in 65% of all injuries, while combined rupture of the ATFL and CFL occurs in approximately 20%.

  • Despite adequate conservative treatment, approximately 20% of patients develop chronic lateral ankle instability.

  • Nonanatomic reconstruction techniques significantly change ankle and subtalar biomechanics

  • Upon failure of conservative treatment, anatomic repair or reconstruction techniques have achieved high percentage of good results.

FormalPara Fact Box 2 – Surgical Options for Treatment of Lateral Ankle Instability

  • The so-called anatomic techniques include isolated repair of ATFL remnant and combined ATFL and CFL repair, with or without Gould augmentation by pants-over-vest reinforcement with inferior extensor retinaculum.

  • If the remnant tissues are considered as irreparable, or in revision surgeries, anatomic reconstruction by using a tendon graft (e.g. gracilis tendon) either open, percutaneous or arthroscopic has produced favourable outcome.

  • Arthroscopic surgical techniques are under development with promising results (at least similar to open techniques while enabling treatment of comorbidities), but more studies are required, particularly in in high-level athletes.

FormalPara Fact Box 3 – Most Frequent Risk Factors for Surgical Treatment of Lateral Ankle Instability

  • Stiffness <5% (reduced ROM >5°)

  • Re-rupture

  • Nerve damage

  • Complications with skin closure

  • Risk factors for worst surgical outcome:

  • Patients with hyperlaxity

  • Very long-standing ligamentous injury (over 10 years)

  • Previous surgery for ankle ligament repair

FormalPara Fact Box 4 – Osteochondral Defects (OCDs) of the Ankle

  • Traumatic and non-traumatic aetiologies have been described.

  • Ankle sprain or chronic ankle instability might be implicated in the aetiology of OCD.

  • Fixation of a large fragment shall be performed whenever possible.

  • Microfracture is still the most popular treatment once it has favourable results, low aggression and low cost.

  • Moreover, no surgical treatment has proven superiority over any other in this field so far.

  • Tissue engineering and regenerative medicine approaches promise new options for the future.

FormalPara Fact Box 5 – Ankle Anterior and Posterior Impingement

  • Both are based on clinical diagnosis while imaging might be helpful in preoperative planning.

  • Arthroscopic approach of bony or soft tissue impingement is the rule upon failure of conservative treatment.

  • Both are treated in outpatient clinic with immediate range of motion and weightbearing. Full return to activity is usually achieved between 4 and 6 weeks.

  • It is very important to start active dorsiflexion-plantarflexion exercises from day one to avoid stiffness.

1 Introduction

Ankle lateral instability is a very frequent injury which might cause functional limitations in both athletes and in the general population. It has been stated that ankle sprain is one of the most frequent injuries during sports activity; however, criteria for return to activity are under-reported [1]. The rapid direction and step’s changes in addition to landings from falls, collisions and jumps present players with high injury risk during sports. These manoeuvres, which are key elements of the sport at the top level, produce high loads to the hindfoot, frequently exceeding the mechanical resistance of the ankle joint [2, 3].

An inversion ankle sprain is the most frequent cause of acute ankle injury in sports [4]. This typically occurs after a jump, when landing on the lateral border of the foot, but might also occur if the foot gets locked on the ground, while the body continues to turn.

This sudden increase in inversion and internal rotation forces, combined with either dorsi- or plantarflexion, produces sufficient strains to rupture the ankle lateral ligaments, causes concomitant osteochondral lesions or aggravates anterior or posterior joint impingement [5, 6]. The anterior talofibular ligament (ATFL) is injured first; then with increased inversion and rotation, the calcaneofibular ligament (CFL) is also torn (Fig. 4.1) [7]. In about 65% of cases, an isolated lesion of the ATFL will occur, while combined ruptures of the ATFL and CFL happen in around 20% [8, 9]. The posterior talofibular ligament (PTFL) is rarely injured during inversion sprain [10, 11]. In approximately 10–15% of all inversion injuries, there is a total rupture of the lateral ankle ligaments [12]. Moreover, 50% of these cases have concomitant other injuries in the joint (medial ligament injuries, syndesmotic injuries, loose bodies, osteochondral defects (OCDs)) [13].

Fig. 4.1
figure 1

(A) Anterior drawer test in which the surgeon induces anterior translation force (red arrow). The anterior dislocation of the talus makes visible a sulcus sign (blue circle). (B) Tilt test in which a rotational force (yellow arrow) is induced suggesting calcaneofibular ligament injury. (C) Varus stress X-ray reproducing the tilt test and demonstrating impingement of the talus within the ankle mortise

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If not treated adequately and in due time, these injuries will lead to chronic ankle instability (CAI) and might have severe consequences such as osteochondral defects, ankle impingement, synovitis and post-traumatic ankle arthrosis (given the recurrence of ankle sprains) [14,15,16,17]. Furthermore, patients with CAI have altered joint kinematics which in turn lead to an increased chance on recurrent ankle sprains [18]. These persistent “microtraumatisms ” will increase the possibility for osteochondral injuries as well as anterior or posterior impingement. In case of failure of conservative treatment, patients who suffer from recurrent ankle sprains can be effectively treated by means of surgical stabilization [19,20,21]. With the objective to minimize surgical aggression and enable immediate treatment of comorbidities, arthroscopic techniques have been developed and optimized, providing at least similar outcome as open techniques [20].

In order to preserve joint kinematics and optimize clinical results, present surgical techniques aim to restore the “normal” anatomy [22]. Use of peroneal tendons as used in the past is therefore not advised unless this is considered to be the last option [22]. The two most popular techniques include anatomic repair and anatomic reconstruction [22]. A third technique, receiving less attention in current literature, is capsular shrinkage [23]. By use of radiofrequency, the joint capsule is heated which induces shrinkage of collagenous structures aiming to tighten the ATFL (without any foreign or allogeneic material such as suture anchors or tendon grafts) [24]. Despite overall good results, de Vries et al. [23] reported the technique to be unable to modify objective ankle joint laxity.

2 From Ankle Sprain to Chronic Lateral Ankle Instability

Although the natural history of ankle sprains is not completely understood, the inherent stability of the ankle mortice and its congruency might contribute to the fact that complete but isolated ATFL ruptures have good prognosis. Most patients are successfully treated with functional treatment [25]. In some selected cases, especially in elite athletes, it has been proposed that early surgery can be considered as a first-line treatment to achieve a faster return to play [26, 27].

If no ligament rupture occurs, functional rehabilitation treatment will enable to resume activities in few days/weeks. Pain is used as a guide for patients and doctors. Ruptured lateral ankle ligaments usually require a period of rigid/semi-rigid immobilization followed by soft brace protection or taping (taping has some risk of skin irritation) [28].

Despite adequate conservative treatment, around 20–30% of patients will develop CAI with persistent symptoms (fear of reinjury limiting activity, sense of giving away, and recurrent sprains) [26, 29, 30]. Standardized and reproducible criteria for reporting return to play for athletes are scarce in literature, and there are no objective guidelines to assist us in this determinant decision [1].

CAI derives from several functional and mechanical factors [7, 31, 32]. These include lower-leg proprioceptive deficits, disturbance of normal reflexes and (peroneal) muscle weakness which are relevant contributors to the persistence of the symptoms [31]. Subsequently, a thorough rehabilitation programme that emphasizes proprioceptive, neuromuscular control and balance training must always be followed. Available data report success rates up to 80% after functional rehabilitation programmes [10, 26].

2.1 Principles of Surgical Treatment of Lateral Ankle Instability

Surgery is indicated to restore functional stability upon failure of conservative treatment [25, 30]. The surgical options to treat CAI range from anatomic repair to nonanatomic reconstructions.

Currently, there is insufficient evidence to support any specific superior surgical intervention in the treatment of chronic ankle instability [29, 33].

Nevertheless, nonanatomic reconstruction, as the classic Evans, Watson-Jones or Chrisman-Snook procedures, has been shown to significantly alter the normal biomechanics of the ankle complex, particularly the subtalar joint [8, 9, 34, 35]. Given these concerns [33], and the favourable outcome of anatomic techniques, the former are currently the first line of surgical treatment [36,37,38].

Anatomic open repair was first described in 1966 by Bröstrom et al. [39]. This technique respects the original anatomy by tightening the torn ATFL and CFL to the distal fibula (Fig. 4.2). Two modifications were introduced over time by Gould et al. [40] that advises to suture the inferior retinaculum extensorum (RE) over the proximal ATFL end to augment the repair, and the modification by Karlsson et al. [41] advises to shorten the ligaments were often not disrupted but elongated.

Fig. 4.2
figure 2

(A) Open surgery where anterior tibiofibular (ATFL) and calcaneofibular ligament (CFL) are visible. (B) Open Brostrom repair with repair of the anterior tibiofibular (yellow arrow, ATFL) and calcaneofibular ligament (red arrow, CFL) is reattached to the fibula (blue arrow)

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The functional outcomes of these techniques in its many modifications have been excellent, with success rates reported as high as 87–95% [12, 40, 41]. Retrospective case series of arthroscopic repair techniques have shown successful postoperative results with a high rate of self-reported satisfaction (94.5%), with low rate of complications (0.5–3%) [42,43,44,45].

The rehabilitation protocol after anatomic repair of the lateral ligament follows the functional treatment for acute ligament rupture, with a lower-leg cast for 1 or 2 weeks, followed by 2–4 weeks in a functional brace [37]. To encourage earlier return to play, range of movement exercises and protected loading are recommended after 2 weeks as tolerated. Inversion and rotational exercises should be limited during the first 4–6 weeks. Return to sport is usually possible between 10 and 12 weeks; dynamic postural control tests are considered valuable functional assessment tools to progress in return to full activities [4, 33, 46].

2.2 Recent Advances in Surgery for Ankle Instability

All the anatomic repair techniques depend on the quality of the ligaments’ remnant in order to achieve an effective repair [36]. Karlsson et al. determined risk factors for worst outcome: hyperlaxity, long-standing injuries and previous surgical treatment [41].

When the tissue remnant is considered inadequate for repair, then anatomic reconstruction using a free tendon graft (autograft or allograft), usually the gracilis tendon, has been proposed with favourable outcome [47, 48]. Available clinical data suggest that these anatomic free graft-based reconstructions, either by arthroscopic, percutaneous or open techniques [49], enable favourable outcome in properly selected cases: inadequate remnant or as a salvage/revision procedure [47, 48, 50, 51].

Graft-based reconstructions may lead to increased stiffness once the graft is much stronger than the native tissue [47]. Usually a more aggressive rehabilitation is possible, depending on the intraoperative achieved tension and graft fixation [52]. Song et al. recently showed a midterm better ankle joint function in patients who received an ATFL reconstruction, compared with the Broström procedure [51], but this finding requires further research with larger series and uniform selection criteria followed by randomized studies.

The current trend is on the pursuit of minimally invasive arthroscopic techniques (Fig. 4.3). Based on the favourable outcome of open ligament repair, several authors have described repair techniques aiming to replicate what has been learnt with open surgery and achieve similar repairs with arthroscopic anchor-based approaches [36,37,38, 42, 49, 53]. This might lower the surgical morbidity and shorten the time of recovery [54, 55]. Arthroscopy also enables the treatment of concomitant intra-articular lesions in addition to ankle stabilization [14, 56]. Considering the aforementioned retrospective series, comparative studies for open and arthroscopic anatomic lateral ligament repair have shown similar clinical and biomechanical outcome [20, 54, 55].

Fig. 4.3
figure 3

(A) Arthroscopic view of the ATFL remnant detached from the fibula (yellow arrow); (B) outside view of arthroscopic ATFL repair; (C) arthroscopic view of reattachment of the ATFL remnant (red arrow) to the fibula and knot tying (light blue arrow)

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3 Ankle Osteochondral Defects

An osteochondral defect (OCD) of the talus is a lesion involving the talar articular cartilage and its subchondral bone. Several classifications have been used over time, but the first comes from 1959 from Berndt and Harty [57]. OCDs are usually caused by a single or multiple traumatic events, but non-traumatic, idiopathic OCDs of the ankle have been described [58,59,60,61]. No classification fully addresses the problem, but the anatomic grid proposed by Raikin and Elias has proven to be useful both in the talus and the tibial plafond [62, 63]. The defect initially may involve only superficial cartilage damage caused by shearing stresses, without damage to the underlying subchondral bone, but a bony injury after a high-impact force also can cause a defect [64]. Ankle trauma associated with an OCD often develops leading to the formation of subchondral bone cysts. These cysts are related with persistent deep ankle pain thereby causing functional impairment. Most OCDs of the talus are found on the anterolateral or posteromedial talar dome [65]. Lateral lesions are usually shallow oval shaped, and a shear mechanism has been proposed to be more frequently implicated. This opposes to medial lesions which are usually deeper, and cup shaped, suggesting a mechanism of torsional impaction and axial loading [58, 60]. Despite several theories and basic science studies concerning OCDs of the talus, its aetiology and pathogenesis are still not fully comprehended.

An OCD might have an acute onset. However, the process leading to subchondral cyst formation requires some time, and it’s a slower process [66]. The reason why some OCDs remain asymptomatic is still unclear, while others with apparently similar features cause pain on weightbearing (aggravated by effort), show persistent bone oedema on magnetic resonance imaging and ultimately lead to a subchondral cyst. Understanding this process would be critical in order to prevent progressive joint damage [66].

A traumatic event is commonly accepted as the most important aetiologic factor of an OCD of the talus. For lateral talar defects, trauma has been implicated in 93–98% and for medial defects in 61–70% [67]. OCD aetiology can be divided in non-traumatic and traumatic defects [60]. Vascular aetiology, ischemia, subsequent necrosis, and genetics have been accepted as aetiologic factors [58]. Moreover, OCDs have been found in identical twins and siblings [68]. OCDs are bilateral in 10% of patients [69]. Traumatic cartilage lesions include three categories: microdamage or blunt trauma, chondral fractures and osteochondral fractures [70].

Ankle sprains have a predominant role in the aetiology of traumatic OCDs, once these are probably the most frequent traumatic events leading to these injuries [13]. When a talus twists inside its “bony mortice” during an ankle sprain, the cartilage covering of the talus can be damaged by direct impactions causing a real OCD, bone bruise, cartilage crack or delamination. Shearing forces might cause separation in superficial layer of the cartilage [60]. Loose bodies can be created (and cause even more cartilage damage), or OCDs might remain partially stable in its position (Fig. 4.4). The lesions can either heal and remain asymptomatic, or progress to deep ankle pain on weightbearing and form subchondral bone cysts. IBerndt and Harty were able to reproduce lateral ankle OCDs under laboratory conditions by intensely inverting a dorsiflexed ankle. As the foot was inverted, the lateral border of the talar dome was compacted against the face of the fibula, and when the lateral ligament ruptured it lead to cartilage avulsion. During application of excessive inverting force, the talus rotated laterally in the frontal plane within the mortise, thus impacting and compressing the lateral talar margin against the articular surface of the fibula. With this mechanism, a portion of the talar margin was sheared off from the main body of the talus, causing a lateral OCD. A medial lesion was reproduced by plantarflexing the ankle in combination with slight anterior displacement of the talus on the tibia and inversion and internal rotation of the talus on the tibia [57, 60].

Fig. 4.4
figure 4

(A, B) Arthroscopic view of loose body (red arrow) and talar spur (yellow arrow), causing osteochondral ridge defects (orange arrow on the talar dome). (C, D) CT view of the loose body (red arrow) and talar spur (yellow arrow)

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For this reason, one can assume a tight connection between most ankle OCDs and CAI which is the topic for reflection in the herein presented paper.

3.1 Principles of Surgical Treatment of Osteochondral Defects

Asymptomatic incidental findings of the ankle are not infrequent, including within athletic population [71].

Asymptomatic and/or low symptomatic OCDs can usually be treated conservatively, even if kept under clinical and/or image surveillance. Conservative treatment includes orthobiologics, physiotherapy, periods of rest or immobilization (e.g. Walker Boot) [59, 65].

Regarding the symptomatic ankle OCDs, several approaches are possible depending on the characteristics of the lesion and patient profile. There is no current consensus in literature of clear superiority of any surgical treatment over another either in primary or secondary ankle OCDs [65, 72, 73].

Preoperative planning is of paramount relevance, and it should always include X-rays for alignment assessment and global evaluation. The computed tomography (CT) is a critical method since it provides a relatively more reliable assessment of bone defects, which can be overestimated by the MRI oedema around the defect mainly in T2 sequences. However, the presence of such oedema in T2 suggests activity around the lesion. Moreover, CT lateral view in plantar flexion or dorsiflexion is helpful to determine if it’s possibly an anterior or posterior arthroscopic approach or if an open approach is required (medial malleolar osteotomy for medial defects or lateral ligament detachment and afterwards reinsertion for lateral defects). Arthroscopic approach is currently the preferred and most frequently used for both anterior and posterior compartments [74]. Moreover, when no fixed distraction is used, the percentage of complications is extremely low [75].

Given the lack of evidence of any superior treatment, the author’s approach favours to prefer the less aggressive options. More aggressive, thus more prone to complications or higher cost procedures are considered for secondary or revision surgeries (Table 4.1).

Table 4.1 Practical algorithm for surgical treatment of osteochondral defects of the ankle
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Whenever possible, an ankle OCD which is possible to fix in place (with sufficient size and preferably with some underlying bone) will constitute our first option (Fig. 4.5). Either open or arthroscopic, the “lift, drill, fill, fix” technique should always be considered once it is the one who preserves the most of the native tissue and hyaline cartilage [76] (lift, the defect; drill, by making microfracture or bone marrow stimulation; fill, the defect with bone graft; and fix, the fragment with metallic or bioabsorbable screws or pins).

Fig. 4.5
figure 5

(A) X-ray with visible medial OCD on the talar dome. (B, C) CT confirms OCD with underlying bone and cystic lesions around it. (D) After medial malleolus osteotomy, the OCD is lifted, submitted to bone marrow stimulation and filled with bone autograft. (E) The fragment is fixed. (F) Final view with fixation with compression screw

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In OCDs smaller than 15 mm, excision, curettage and bone marrow stimulation, usually by microfractures (Fig. 4.6), aims to stimulate the underlying subchondral bone bringing “blood” containing growth factors (GFs) and mesenchymal stem cells (MSCs) which will promote fibrocartilage coverage of the defect and provide around 85% of successful outcome at a 5-year follow-up [77]. Given the satisfactory results with minimal aggression, depending on the patient profile and injury characteristics, this approach can also be considered in bigger lesions unable for fixation or secondary injuries [65, 72, 73].

Fig. 4.6
figure 6

(A) Ankle OCD arthroscopic view and removal of unstable fragment; (B) microfracture probe; (C) final look after microfractures; (D) blood coming from the microfracture holes after reliving the tourniquet

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Large cystic lesions, including tibial OCDs, can be addressed by retrograde drilling to lower the pressure within the cyst and filling with bone graft when possible or required.

The osteochondral autologous transplantation surgery (OATS) consists in harvesting osteochondral cylinders from the knee to fill an ankle defect. Despite a high rate of successful outcome stated by the promoters, a systematic review has shown that this technique is linked to a high percentage of complication [78]. So, in our algorithm it remains a salvage procedure for large OCDs or secondary lesions (after failure of previous surgeries).

Cell-based therapies , scaffolds and augmentation with hydrogels, despite being quite promising, have not been able to consistently present superiority to the previously described techniques on the clinical setting. For this reason, and considering their high cost, they remain options for revision surgeries or large injuries without possibility for fixation and not amenable by any of the previous techniques [79,80,81,82,83,84,85,86,87,88,89,90,91,92,93,94,95]. However, we strongly believe in advanced tissue engineering and regenerative medicine approaches for the future.

When all biologic surgical treatments fail, a novel metallic implant designed for secondary defects of the medial talar dome (Hemicap® ) has provided favourable outcome [96].

Finally, realignment by means of the osteotomy (calcaneal sliding (Fig. 4.7) or supramalleolar) is a powerful tool to provide a more favourable biomechanical environment for OCD healing by unloading the affected site [97, 98].

Fig. 4.7
figure 7

(A) Surgical procedure of calcaneal sliding osteotomy ; (B) preoperative X-ray demonstrating severe varus with impingement of the talus on the tibial plafond; (C) final position achieved with improved alignment enabling better load distribution

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As a last resource, ankle fusion or ankle arthroplasty in very selective cases might be the end line treatment [98].

4 Ankle Impingement Syndromes

Repetitive microtrauma to the anterior aspect of the ankle joint might lead to bony spur formation ultimately causing anterior impingement syndrome [99]. This microtrauma might be linked to CAI or repetitive direct impact force (e.g. kicking a ball) [100]. About one third of patients with CAI will experience pain related to ankle impingement. Injury of the anterior-inferior talofibular ligament might lead to the development of a “meniscoid lesion” which might cause soft tissue anterolateral impingement [99]. Impingement is considered as a syndrome, meaning that it is basically a clinical diagnosis in which the key sentence is superficial recognizable pain on palpation. Patients complain of persistent pain in walking, aggravated by climbing stairs (dorsiflexion or local pressure might cause entrapment of soft tissue/synovitis between two hard surfaces). Anterior or anteromedial impingement is usually caused by osteophytes, which are not enthesophytes (Fig. 4.8). They do not result traction once they are included in the limits of the capsule [101]. X-ray (including the AMIC view –anteromedial oblique view) [102] or CT (less frequently MRI) can be useful for preoperative planning and identification of concomitant loose bodies or painful broken osteophytes.

Fig. 4.8
figure 8

(A) CT demonstrating anterior impingement (yellow circle); (B, C) arthroscopic view in neutral position and dorsiflexion where bony impingement is confirmed

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Posterior impingement syndrome concerns a mechanical conflict due to hyperplantarflexion [103]. It can be either acute (os trigonum or Stieda process fracture or dislocation) after trauma [104] or chronic, caused by repetitive microtrauma (which might also be linked to CAI) (Fig. 4.9). Chronic cases can be linked to hypertrophic os trigonum or posterior talar process as well as related fractures or soft tissue impingement (e.g. cysts). It is often observed in footballers, cyclers, swimmers, acro-gymnasts and ballet dancers [105, 106]. It is also a syndrome, where posterior impingement test is most helpful and imaging is used for preoperative planning in most cases [107]. Upon failure of conservative treatment (physiotherapy, injections, shoe wear), surgical treatment is recommended.

Fig. 4.9
figure 9

CT 3D view of plantarflexion ankle with posterior impingement with os trigonum (yellow arrow)

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4.1 Principles of Surgical Treatment of Anterior Impingement

The treatment of anterior, anteromedial, anterolateral, bony or soft tissue ankle impingement is nowadays achieved mainly by arthroscopic approach. The medial portal is created in dorsiflexion, medial to the crossing line between the anterior tibialis tendon and the joint line [108]. This way the cartilage surface is protected under the tibial plafond, and the working space is “opened”. The lateral portal is performed under transillumination and again in dorsiflexion to avoid nerve damage (the superficial peroneal nerve moves posteriorly). The tibial osteophyte shall be removed from superior to inferior and the talar osteophyte from distal to proximal to fully control the bone morphology [101, 107]. It is recommended to minimize aggression which will ultimately lead to a faster recovery and avoid secondary instability due to loss of bony contact (if too much bone is removed) [101, 107]. This is an outpatient procedure, and the patient can weight bear from day 1 if tolerated. It is very important to start active dorsiflexion-plantarflexion exercises from day 1 to avoid stiffness. Stiches are removed at 2 weeks, and full return to activity is possible within 4–6 weeks. Satisfactory results have been published around 85–90% at a 5-year follow-up, and around 80% remain asymptomatic at an 8-year follow-up [101, 107].

4.2 Principles of Surgical Treatment of Posterior Impingement

The two-portal endoscopic approach for the hindfoot described by Van Dijk et al. created a revolution in the treatment of these conditions [109], either bony or soft tissue impingement. It lowered dramatically the surgical aggression as it is an outpatient procedure, and the patient can weight bear from day 1 if tolerated. Once more, it is very important to start active dorsiflexion-plantarflexion exercises from day 1. Stiches are removed at 2 weeks, and full return to activity is possible within 4–6 weeks for isolated procedures [103]. The flexor hallucis longus tendon is used as a medial landmark to define a safe working area to avoid the medial neurovascular bundle.

The knowledge of anatomy is fundamental, and the step-by-step technique has been described elsewhere [110]. Effort shall be made to remove the os trigonum in one piece to avoid living small loose bodies behind.

5 Final Remarks

  • The majority of inversion ankle sprains are effectively managed with functional conservative treatment, even in the case of ligament rupture.

  • There is increasing evidence on the effectiveness of arthroscopic approach for CAI treatment. So far, the reported outcomes are at least equivalent to open techniques. However, more high-level studies are still needed.

  • When repair of the remnant tissue is no longer possible, anatomic reconstruction by using a free graft (auto- or allograft) has provided good results and is also suitable for revision cases. Moreover, replication of the anatomy may facilitate to overcome the limitations of previous nonanatomic techniques.

  • Osteochondral defects can have traumatic and non-traumatic aetiology. CAI is a major cause of traumatic OCDs.

  • Fixation of an OCD should be performed whenever possible. Besides this, the most frequent surgical treatment remains bone marrow stimulation (e.g. microfractures). This relies on the high percentage of satisfactory results and lower aggression, as well as the fact that no surgical procedure has, so far, demonstrated consistent advantage over the former.

  • Tissue engineering and regenerative medicine promises to provide new more effective options for the future.

  • Anterior and posterior impingement syndromes are based on clinical diagnosis while imaging is helpful in preoperative planning.

  • Aetiology can be traumatic with the contribution of repeated microtrauma connected to CAI.

  • Arthroscopic/endoscopic approaches for both these entities enable high percentage of good results with minimal complications and fast return to activity.

  • CAI, as herein described, is a major entity which can cause further damage through time in the ankle joint. Effective and timely treatment will avoid further joint damage.