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Chronic ankle instability in the Swiss orienteering national teamChronische Instabilität des oberen Sprunggelenks im Schweizer Orientierungslauf – Nationalkader

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Summary

Background

Up to 40% of the patients with acute ankle sprains (AAS) develop chronic ankle instability (CAI) either as a mechanical (MAI) or functional ankle instability (FAI).

Methods

43 athletes of the Swiss Orienteering National Team (women 20; men 23) were examined clinically and biomechanically with the Biodex Balance System (BBS).

Results

The history of AAS was documented in 37 athletes (86%). Clinical and biomechanical examination evidenced CAI in 49 ankles (57%). The CAI subgroups were: (A) MAI with normal functional stability, 25 (29%); (B) FAI with normal mechanical stability, 18 (21%); and (C) combination of MAI and FAI, 6 (7%).

Discussion

An orienteering athlete has high risk for AAS and the development of CAI. CAI exhibits three different subgroups: MAI alone, FAI alone, combination of MAI and FAI. In order to compensate MAI, and therefore long-term joint sequelae, specific training for improvement of functional ankle stability is advised.

Zusammenfassung

Hintergrund

Bis zu 40% der Patienten entwickeln nach einer akuten Distorsion eine chronische Sprunggelenkinstabilität, welche sich entweder als mechanische oder funktionelle Instabilität zeigt.

Methoden

43 Athleten des Schweizer Orientierungslauf-Nationalkaders (Frauen 20; Männer 23) wurden klinisch und biomechanisch mit dem Biodex Balance System (BBS) untersucht.

Resultate

37 Athleten (86%) berichteten über akute Distorsionen. Klinisch und biochemisch zeigten sich bei 49 (57%) Zeichen einer chronischen Sprunggelenkinstabilität. Die Subgruppen waren: (A) mechanische Instabilität mit normaler funktioneller Stabilität 25 (29%); (B) funktionelle Instabilität mit normaler mechanischer Stabilität 18 (21%); (C) eine Kombination von mechanischer und funktioneller Instabilität 6 (7%).

Diskussion

Orientierungsläufer haben ein hohes Risiko für akute Distorsionen und chronische Instabilität des Sprunggelenks. Chronische Instabilität zeigt sich in drei Gruppen: isolierte mechanische Instabilität, isolierte funktionelle Instabilität, Kombination von mechanischer und funktioneller Instabilität. Um Langzeitschäden kompensieren zu können, wird spezifisches Training zur Stärkung der funktionellen Stabilität empfohlen.

Introduction

Orienteering is an endurance sport in which athletes deal with tough terrain while performing highly cognitive orientation work. Orienteering is one of the most popular sports in Scandinavia [15], [20]. Athletes suffer among other sport-specific injuries typically and frequently from acute ankle sprains (AAS) [15], [20]. Despite the efficacy of non-operative treatment and physical rehabilitation management of ankle sprains [25], 10% to 30% of AAS patients may experience chronic ankle instability (CAI) [16]. Pathomechanically, CAI can be caused by mechanical ankle instability (MAI), functional ankle instability (FAI) [3], [4], [9], or a combination of both, MAI and FAI [23].

MAI is a ligament insufficiency mostly based on the ligamentous elongation or discontinuity. The most common MAI is the lateral ankle instability with disruption of the anterior fibulotalar ligament [7], [13]; followed by a lesion of the fibulocalcanear ligament. Less often, an insufficiency of the medial hindfoot ligaments may lead to medial ankle instability [12]. In combination, lateral and medial ankle instability represent a rotational ankle instability [12]. Although for diagnostics of MAI clinical physical examination (anterior drawer test, talar tilt tests) [6], stress radiography [5], instrumented arthrometry [19], or diagnostic arthroscopy [11] have been described, only clinically physical examination and intraoperative diagnostic arthroscopy have been established for daily use.

Functional instability is described as an impairment of the neuromuscular joint stability control, which consists of three parts the afferent (e.g. proprioception, nerve-conductance velocity [25]), the central (e.g. spinal integration processes, pain inhibitors), and the efferent part (e.g. nerve-conduction velocity, strength) [9]. Often, the terms sensorimotor and postural are used synonymously to neuromuscular. Measuring all sub-factors of FAI, reported data have been very inconsistent and objective assessment of overall FAI remained difficult.

Differentiation of MAI and FAI is important to direct adequate treatment and prevention. FAI can only be addressed by functional, sensorimotor training [25]. MAI can either be compensated by a strong neuromuscular function or treated by operative ligament reconstruction. Prevention may be done by external stabilization or sensorimotor training [25]. Although many studies have focused singly on FAI or MAI aspects of CAI, no studies tried to simultaneously address the link between both subtypes of CAI, MAI and FAI, in a high-risk athlete's cohort, as in a professional orienteering team.

Therefore, the aim of this study was to evaluate: (a) the rate of ankle sprains and CAI in a national orienteering team, (b) the distribution of the CAI subtypes, FAI, MAI, and combination of both and (c) possible athletes’ coping mechanisms to overcome CAI.

Section snippets

Methods

In the current study athletes of the Swiss National Orienteering Senior and Junior Elite Team were examined clinically and biomechanically during their annual medical, laboratory, and sports medical check-up. The national team achieved the number one world position in the last years.

Out of 51 athletes in the National Team, 43 athletes (female, 20; male, 23; average age, 22.5 years; range, 18 to 31) participated in this study. Eight athletes could not take part due to absence (n=6), illness

Acute sprains

A history of an acute ankle sprain (AAS) was mentioned by 37 athletes (86%). Of these 37 athletes, 31 athletes (72% of all athletes) suffered recurrent ankle sprains. In seven athletes (19%) unilateral ankle was affected, in 30 athletes (81%) bilateral ankles were affected.

Actual ankle status

At clinical examination, 16 athletes (37%) complained subjectively of current foot and ankle pain. The VAS score was in average 4.0 points (range, 1 to 10). Tenderness was found in 29 feet (34%, Table 3). The foot arch

Discussion

This study provides relevant information on AAS and CAI for sports physicians, surgeons, and trainers. In the Swiss Orienteering National Team, which included 43 highly professional athletes, there was a prevalence of 86% for acute ankle sprain (AAS) (n=37). Seven athletes (16%) suffered unilateral and 30 athletes (70%) bilateral ankle sprains in their past. This proves that Orienteering has a high rate of ankle sprains and CAI and has to be considered as high-risk sport for these injuries

Conclusion

This study analyzed CAI in 43 athletes of the Swiss Orienteering National Team. Orienteering is found to be a high-risk sport for AAS and CAI. In CAI, FAI was not dependent on MAI. Therefore, they have to be considered as two different entities. It was found that in 29% of athletes a strong neuromuscular potential can compensate a MAI. Considering this, it may be concluded that functional stability may prevent chronic unstable ankles of long-term sequelae like ligamentous ankle osteoarthritis.

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    Submitted to Sportorthopädie Sporttraumatologie Dezember 2009 – Revision Februar 2010.

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