Increased Femoral Neck Anteversion is Prevalent in Male Elite Youth Soccer Players with Chronic Ankle Instability

Abstract

Purpose

The aim of this study was to compare femoral neck anteversion (FNA) and determine the prevalence of increased FNA in male elite youth soccer players with and without chronic ankle instability (CAI). Secondary aims were to evaluate the utility of FNA in predicting CAI and compare ankle and hip muscle strength in the two groups.

Materials and methods

The study included a total of 44 male elite youth soccer players, 22 with CAI (mean age 16.09 ± 1.34) and 22 without CAI (mean age 16.73 ± 1.28). FNA was measured with Craig’s test, range of motion (ROM) was measured with a universal goniometer, and ankle and hip maximum voluntary isometric strength (MVIS) was measured with a handheld dynamometer.

Results

The mean FNA angles of the CAI and control groups were 15.82° ± 1.44° and 12.09° ± 2.37°, respectively (p > 0.05). FNA was greater than 15° in 72% of the CAI group versus 4% of the control group (p < 0.05). A 1° increase in FNA was associated with threefold higher odds of having CAI (odds ratio 3.06, 95% confidence ratio: 1.37–6.81, p < 0.01). Mean ankle eversion and hip abduction MVIS values were 2.67 ± 0.52 Nm/kg and 3.83 ± 0.48 Nm/kg in the CAI group, compared to 3.03 ± 0.58 Nm/kg and 4.46 ± 0.98 Nm/kg in the control group, respectively (p < 0.05).

Conclusion

Male elite youth soccer players with CAI had greater FNA and were more likely to have increased FNA than those without CAI. They also exhibited ankle eversion and hip abduction muscle strength deficiencies compared to peers without CAI. FNA may be useful as a predictor of CAI in male elite youth soccer players.

Introduction

Chronic ankle instability (CAI) is a condition marked by the repetitive occurrence or feeling of the ankle giving way; continuing symptoms like pain, weakness, or reduced ankle range of motion (ROM); lessened self-reported function; and repeated ankle sprains persisting for more than 1 year after the primary injury [1]. The prevalence of CAI in the youth athletic population is 20% [2]. CAI is believed to have a multifactorial etiology, with numerous anatomical, behavioral, physical, and environmental factors possibly contributing to its development [3–15].

Femoral neck anteversion (FNA) refers to the angle between the femoral neck and femoral shaft and indicates the degree of torsion of the femur [16]. Increased FNA has been implicated as the cause of certain musculoskeletal injuries [17–20]. Hip pain [19], anterior cruciate ligament injury [17], patellofemoral pain [20], and chronic low back pain [18] are especially associated with increased FNA. A larger FNA angle corresponds to greater internal rotation of the lower extremity and consequently affects the biomechanics of the ankle and foot joints [21]. To our knowledge, the relationship between increased FNA and acute or chronic ankle sprain has not been investigated previously in any population.

Although there is some evidence that ankle eversion and hip abduction strength deficits may be risk factors for CAI, the relationship between ankle and hip muscle strength and CAI in different populations should be further examined [22]. Moreover, the prevalence of FNA in athletes with CAI has not been previously investigated. Although there is some evidence that structural variables such as bilateral weight differences and Q angle may be predictors of lower extremity injuries (including ankle injury) in athletes [23], there has been no study examining the predictive value of increased FNA for CAI. We hypothesized that increased FNA is more common in male elite youth soccer players with CAI than in those without CAI and that FNA may be a predictive parameter for CAI. Therefore, the primary aim of the study was to compare FNA values and determine the prevalence of increased FNA in male elite youth soccer players with and without CAI. Our secondary aims were to evaluate the predictive value of FNA for CAI and compare ankle and hip muscle strength and ROM between male elite youth soccer players with and without CAI.

Materials and Methods

Study Design and Participants

This cross-sectional study was conducted in Konya, Turkey in accordance with the Declaration of Helsinki. Ethical approval was obtained from a local ethics committee (date: 02.03.2022, approval number: 2022/20–157).

A total of 44 male elite youth soccer players, 22 with CAI and 22 without CAI, were included in the study. A sports physician (XX) and an orthopedic specialist (XXX) identified the CAI and non-CAI participants. Palpation and provocation tests were used for clinical diagnosis. The provocation tests used were the anterior drawer, talar tilt, posterior tilt, eversion stress test, and squeeze test [24]. The participants were also questioned to determine whether they met the International Ankle Consortium selection criteria. These criteria include a) a history of at least one significant lateral ankle sprain, which must have occurred at least 12 months prior to participating in the study, and b) at least one of the following: a history of “giving way” on the previously sprained ankle, which must have occurred at least twice in the past six months; experiencing a recurrent sprain, which must have occurred twice or more in the injured ankle; and/or having a feeling of ankle instability during daily or sports activity [1]. In addition, the participants were asked to complete the Identification of Functional Ankle Instability (IdFAI), a self-report scale recommended for use in identifying CAI. Simple and easy to apply, the IdFAI contains 9 items rated on a 5-point Likert scale. Those with a scale total score above 10 are considered to have CAI. The version adapted to Turkish was shown to be valid and reliable [25].

Inclusion and Exclusion Criteria

Inclusion criteria for the participants with CAI were being 14–18 years of age, having clinical symptoms of ankle instability, fulfilling the International Ankle Consortium selection criteria for CAI patients, and having an IdFAI score of 11 or higher. The inclusion criteria for the control group were being 14–18 years of age, having no history of significant lateral ankle sprain or clinical symptoms of ankle instability, and having an IdFAI score of 10 or lower. Exclusion criteria were having an acute lower extremity injury, a history of lower extremity surgery, or a history of lower extremity fracture.

Outcomes

The participants’ FNA, ankle and hip ROM, and ankle and hip maximum voluntary isometric strength (MVIS) measurements were obtained by three experienced physiotherapists (XX, XX, and XX) who conducted the assessments together and were blind to the participants’ CAI diagnoses.

Primary Outcome

FNA, also called femoral torsion or femoral version, is measured as the angle between the projection of two lines perpendicular to the femoral shaft in the axial plane; the first line passes through the proximal femoral neck region, and the second passes through the distal condyle region (Fig. 1) [16]. FNA increases significantly from 0° in early fetal development to over 30° at birth. During childhood, there is a steady decrease in anteversion of approximately 1.5° per year until the completion of growth, eventually reaching 15° in adulthood [26]. Females have slightly more femoral anteversion than males. Median FNA angles in the 2–4, 4–6, 6–8, 8–10, 10–12, 12–14, and 14–16 years age groups have been reported as 33°, 28°, 26°, 25°, 22°, 21°, and 16°, respectively, and as 15° in adults [27]. FNA can be measured with imaging methods such as ultrasound, radiography, and magnetic resonance imaging, or it can be evaluated with clinical tests such as Craig’s test [16].

Fig. 1.

Femoral neck anteversion (FNA) of the right femur

In this study, FNA was measured with Craig’s test, which has been reported to be valid and reliable for FNA measurement [16, 28]. While the participant lay in the prone position, the clinician stood on the contralateral side of the hip that would be tested. The hip on the tested side was in extension and the knee was in 90° flexion. The clinician palpated the trochanter major with one hand and internally rotated the hip with the other hand. When the trochanteric prominence reached its most lateral position, the angle between the tibia and the vertical plane was measured with a goniometer to determine the FNA (Fig. 2) [28].

Fig. 2.

Measurement of femoral neck anteversion with Craig’s test

Secondary Outcomes

Ankle and hip ROM was measured with a universal goniometer (Baseline^® Plastic Goniometer-HiRes^™ 360-degree head, 12-inch arms). Dorsiflexion ROM was measured in the prone position [29], plantarflexion ROM was measured in the supine position [30], and inversion and eversion ROM was measured in the side-lying position [31]. Dorsiflexion goniometric ROM measurement was reported to have excellent intrarater and fair to good interrater reliability [29]. Although no clear reliability results have been reported for the goniometric measurement of plantarflexion ROM, some findings indicate that results consistent with those of other measurement methods can be obtained [30]. It has also been reported that inversion and eversion ROM measurements have high or moderate interrater reliability [31]. We obtained hip ROM measurements in supine, prone, and sitting positions. The goniometric measurement of hip ROM is affected by the movements of the lower and upper joints; however, the goniometer can be safely used in clinics to measure hip joint movements [32]. In this study, three active ROM measurements were made for each direction of motion, and the average of the measurements was recorded as the active ROM result [31].

MVIS measurements of the ankle and hip muscles were obtained using a handheld dynamometer (MicroFet 2 HHD, Hoggan Health Industries, Inc., West Jordan, UT). For the ankle, MVIS measurements were obtained in the supine position for the dorsiflexor [33] and plantar flexor [34] and in the side-lying position for inversion and eversion [35]. For the hip muscles, measurements were performed in supine, prone, side-lying, and sitting positions [36]. The clinician instructed the participants to move their ankle or hip in the direction being measured but prevented movement by applying resistance. The clinician encouraged the participants to produce maximum force and asked them to maintain it for five seconds. At the same time, the clinician prevented compensation by giving warnings [33–36]. Three consecutive measurements were made at 30-s intervals. The first measurement was considered a trial, and the mean of the next two measurements was recorded as the MVIS result. A 5-min rest period was provided between MVIS measurements of the two different muscle groups. Relative MVIS was calculated by dividing MVIS by body weight [37].

Statistical Analysis

Statistical analyses were performed by two members of the research team (XX, XX). The sample size of the study was determined using G*Power 3.1.7 for Windows (G*Power from the University of Düsseldorf, Düsseldorf, Germany) based on a power calculation to detect between-group differences in Craig’s test results. The calculation was based on Craig’s test data of participants with and without anterior cruciate injury in a study by Nakase et al. [38]. According to the calculation, a total of at least 40 participants, 20 in each group, were necessary for the study to have at least 80% power (effect size = 0.81, alpha = 0.05, 1-beta = 0.80, actual power = 0.81).

The SPSS (version 20; IBM Corp.) program was used for the data analysis. The conformity of the data to normal distribution was determined using visual measures (histogram and Q-Q plots), analytical methods (Shapiro–Wilk test), and coefficients of skewness and kurtosis. Continuous variables were expressed as mean ± standard deviation values. Categorical data were compared with Pearson’s chi-square test. Student’s t-test was used to compare the means between the two groups. Logistic regression analysis was used to determine whether FNA, ankle eversion MVIS, and hip abduction MVIS predicted CAI. A value of p < 0.05 was accepted as statistically significant.

Results

The mean age of the CAI and control groups were 16.09 ± 1.34 and 16.73 ± 1.28 years, respectively (p > 0.05, Table 1). The mean number of recurrent ankle sprains in the CAI group was 2.73 ± 1.03. Both groups played one football match per week. Other training data of the groups are given in Table 1.

Table 1.

Demographic features of the participants

	CAI Group (n = 22) Mean ± SD	Control Group (n = 22) Mean ± SD	pa
Age (years)	16.09 ± 1.34	16.73 ± 1.28	0.12
Height (cm)	177.46 ± 8.52	180.36 ± 5.19	0.18
Weight (kg)	69.31 ± 6.39	72.77 ± 6.13	0.08
Training age	7.05 ± 1.70	7.46 ± 2.26	0.52
Number of training workouts per week	4.82 ± 0.39	4.77 ± 0.43	0.72

CAI: Chronic ankle instability, SD: Standard deviation, ^a Student’s t test

Craig’s test results were > 15° in 72.7% of participants in the CAI group and 4.5% of those in the control group (Fig. 3). The mean Craig’s test result was 15.82° ± 1.44° in the CAI group and 12.09° ± 2.37° in the control group (p > 0.05, Fig. 4). Mean ankle eversion MVIS values of the CAI and control groups were 2.67 ± 0.52 and 3.03 ± 0.58 Nm/kg, respectively (p > 0.05), while hip MVIS values were 3.83 ± 0.48 and 4.46 ± 0.98 Nm/kg, respectively (p < 0.05, Table 2). The results of logistic regression analysis indicated that FNA was a significant predictor of CAI (p < 0.01, Table 3).

Fig. 3.

Prevelance of increased femoral neck anteversion

Fig. 4.

Craig’s test results of the participants

Table 2.

FNA, ROM, and MVIS of participants

		CAI Group (n = 22) (mean ± SD)	Control Group (n = 22) (mean ± SD)	pa
Ankle ROM	Inversion (°)	15.32 ± 3.55	14.86 ± 4.85	0.73
	Eversion (°)	9.64 ± 2.26	11.27 ± 3.31	0.06
	Plantar flexion (°)	52.41 ± 10.59	47.86 ± 9.79	0.15
	Dorsiflexion (°)	12.41 ± 4.46	12.77 ± 3.52	0.77
Hip ROM	Abduction (°)	30.68 ± 8.32	31.32 ± 6.35	0.77
	Adduction (°)	20.77 ± 4.92	22.14 ± 7.24	0.47
	Flexion (°)	123.18 ± 6.25	124.73 ± 8.21	0.49
	Exstension (°)	19.14 ± 5.51	19.18 ± 3.49	0.97
	Internal rotation (°)	32.77 ± 9.40	34.55 ± 9.33	0.53
	External rotation (°)	31.91 ± 8.84	34.36 ± 7.92	0.34
Ankle MVIS	Inversion (Nm/kg)	2.54 ± 0.89	2.84 ± 0.41	0.17
	Eversion (Nm/kg)	2.67 ± 0.52	3.03 ± 0.58	0.03
	Plantar flexion	3.58 ± 0.68	3.73 ± 0.69	0.47
	Dorsiflexion (Nm/kg)	1.09 ± 0.25	1.03 ± 0.18	0.32
Hip MVIS	Abduction (Nm/kg)	3.83 ± 0.48	4.46 ± 0.98	0.01
	Adduction (Nm/kg)	2.93 ± 0.66	3.27 ± 0.87	0.15
	Flexion (Nm/kg)	2.91 ± 0.59	3.02 ± 0.71	0.57
	Exstension (Nm/kg)	2.97 ± 0.53	3.02 ± 0.50	0.70
	Internal rotation (Nm/kg)	2.72 ± 0.75	2.73 ± 0.91	0.66
	External rotation (Nm/kg)	2.28 ± 0.79	2.28 ± 0.71	0.99

FNA: Femoral neck antervison, ROM: Range of motion, MVIS: Maximum voluntary isometric muscle strength, CAI: Chronic ankle instability, SD: Standard deviation, ^a Student’s t test, *p < 0.05

Table 3.

Predictive power of FNA, hip abductor MVIS, and ankle eversion MVIS on CAI

	Beta	Standard Error	Wald	pa	OR (95% CI)
FNA	1.12	0.41	7.45	< 0.01*	3.06 (1.37 − 6.81)
Ankle eversion MVIS	− 0.75	1.33	0.31	0.58	0.47 (0.04 – 6.48)
Hip abduction MVIS	− 2.14	1.17	3.34	0.07	0.12 (0.01 – 1.17)

FNA: Femoral neck anteversion, MVIS: Maximum voluntary isometric muscle strength, CAI: Chronic ankle instability, ^a Binary logistic regression, *p < 0.05

Discussion

The main findings of this study were that among male elite youth soccer players, increased FNA (> 15°) was significantly more frequent among those with CAI compared to those without CAI, and that male elite youth soccer players with increased FNA were more likely to suffer from CAI. Furthermore, male elite youth soccer players with CAI were found to have weaker ankle evertors and hip abductors compared to those without CAI.

CAI has a range of multifactorial etiologies, including sensory-perceptual, pathomechanic, and motor-behavioral disorders, and is also influenced by other individual factors (e.g., demographics, medical history, physical attributes, psychological profile) and environmental factors (e.g., physical activity and sport demands, social support, access to health care) [3]. Predisposing factors for CAI include limited dorsiflexion [4], pathomechanical issues (e.g., increased eversion of the hindfoot, varus alignment of the knee, and lower arch height of the support leg during landing) [5], decreased ankle eversion muscle strength [6–8], hip muscle strength deficits [9–14], and impaired postural stability [15]. However, considering its relationship with other lower extremity injuries, it is thought that FNA may also contribute to the multifactorial etiology of CAI [17, 18, 20].

In our study, the prevalence of increased FNA was remarkably higher in the CAI group (72.7%) than in the control group (4.5%). The mean FNA angle was significantly larger among male elite youth soccer players with CAI, and each degree of increase in FNA angle was associated with threefold higher odds of CAI according to logistic regression analysis. It is known that FNA is associated with musculoskeletal complaints. Lerch et al. reported that abnormalities in the femoral version are quite common in patients with hip pain who are eligible for hip-preserving surgery, and severe abnormalities were seen in one in six patients [19]. Alpay et al. reported that increased FNA was associated with anterior cruciate ligament injury and recommended that clinicians evaluate FNA in patients with anterior cruciate ligament deficiency [17]. Wheatley et al. also reported that increased femoral anteversion worsens patellofemoral joint load alignment, which causes patellofemoral pain [20]. Finally, Khoury et al. stated that increased femoral anteversion may contribute to an increase in lumbopelvic pain by affecting the capsulolabral and muscle-tendinous structures of the hip and lumbar spine [18]. To the best of our knowledge, our study is the first to investigate the relationship between FNA and CAI, and the results suggest that increased FNA in male elite youth soccer players may be a predictive factor for CAI, which may provide a unique contribution to the literature. FNA alters locomotion [39] and adversely affects postural stabilization [40]; therefore, increased FNA may increase susceptibility to CAI. There are findings indicating that FNA values are higher in individuals who can perform extreme hip movements such as ballerinas–i.e., individuals whose hip joints are lax [41]. Therefore, an increased Craig’s test value may be a result hyperlaxity. The combined effect of FNA and hyperlaxity, which is already a risk factor for CAI [3], may have precipitated the development of CAI in the participants.

Different FNA values are expected for different athletic populations because mechanical loading during everyday movements and exercise is one of the key factors in the morphological development of the femoral head and neck [42]. Agricola et al. reported that cam deformity in young soccer players developed gradually during skeletal maturation, likely halting its progression with the closure of the growth plate [43]. However, it is known that hip functionality is affected depending on morphological development. van Klij et al. reported that the presence of cam deformity had a direct effect on hip joint ROM in elite young male soccer players [44]. Except for data presented in a few studies, FNA values have not been defined for soccer players of different age groups and sexes [45, 46]. Daneshmandi et al. reported a mean FNA angle of 15.7° ± 7.01° in female athletes [45]. Chiaia et al. reported that elite female soccer players’ FNA angles were 23.0° ± 5.1° in the dominant leg and 22.0° ± 4.1° in the nondominant leg [46]. In our study, the FNA angles of the CAI and control groups were 15.82° ± 1.44° and 12.09° ± 2.37°, respectively. Factors such as the measurement methods used, the landmarks used during measurement, and heredity make it difficult to establish reference values according to age or sex in soccer players [16]. Future studies may focus on reference FNA values obtained with specific measurement methods for elite young soccer players in different age groups.

Our results indicate that ankle evertor muscle strength is lower in elite male youth soccer players with CAI compared to peers without CAI. The relationship between ankle strength and CAI has been studied for many years, and current information indicates that decreased evertor muscle strength may be a risk factor for CAI [6–8]. In their meta-analysis, Arnold et al. also reported that concentric evertor muscle strength was decreased in individuals with CAI [6]. Santos and Liu found that individuals with CAI had lower evertor muscle strength in the affected ankle compared to both their unaffected extremity and a control group [8]. A more recent systematic review noted that individuals with CAI have deficits in eversion and inversion muscle strength [7]. However, the relationship between CAI and the strength of the dorsiflexor, inverter, and plantar flexor muscles and has not been fully elucidated [22]. Our results support the literature indicating that evertor muscle strength is decreased in individuals with CAI, and to our knowledge this is the first study showing a decrease in ankle eversion MVIS in male elite youth soccer players with CAI. Insufficient evertor muscle strength may cause CAI in these individuals because these tissues are unable to adequately support the lateral capsuloligamentous and bony stabilizers [47].

According to our study results, isometric hip abduction strength was also lower in male elite youth soccer players with CAI than in those without CAI. It has been reported that hip muscle strength deficit is a risk factor for lateral ankle sprain [9, 12, 14]. DeJong et al. determined in their meta-analysis that individuals with CAI have strength deficits in all three movement planes, which develops as a proximal adaptation to CAI [10]. Studies by McCann et al. and Hubbard et al. also showed that individuals with CAI had lower isometric strength in hip extension and hip abduction, respectively, compared to those without CAI [11, 13]. Thus, our study results regarding hip muscle strength are consistent with those in the literature reporting hip abductor muscle strength deficiencies. As hip abductor strength is associated with dynamic balance [48], hip abduction weakness may cause CAI by negatively affecting dynamic balance.

This study has some limitations. Since the study only presents the data of male soccer players at a certain age, the results may not be applicable to older or younger players, female players, or other sports branches. In addition, capsuloligamentous and muscle tensions may have influenced our results by affecting Craig’s test results. Moreover, acetabulum shape may be another uncontrolled factor that may have affected Craig’s test results [49]. In terms of MVIS measurements, the participants with CAI may have avoided maximum isometric force production due to kinesiophobia and fear of re-injury [50]. As FNA, ROM, and MVIS were measured together by the same researchers, there was no assessment of intrarater and interrater reliability in this study [36]. Difficulties in aligning the fixed and mobile arms of the goniometer and the goniometer center with the reference points during ROM and FNA measurements of the ankle and hip joints may have affected the ROM and FNA results [31]. Although the investigator was cautioned against reading the goniometer results until the proper alignment of the goniometer was achieved, their knowledge of ROM reference values may have been a source of bias [32].

Supporting the findings obtained from this cross-sectional study with future longitudinal studies conducted with larger samples and athletes from different sports branches will provide a better understanding of the subject. In addition, since Craig test results may be affected by the test procedure of the clinician conducting the test, more definitive results can be achieved with new research supported by radiological results. Although in this study the diagnosis of CAI was made by a sports physician and orthopedist according to certain criteria, the use of randomized sample selection in future studies may provide a better representation of the population. Rehabilitative approaches (such as increasing ankle evertor and hip abductor muscle strength), training program changes, and biomechanical interventions (such as foot insoles) may support the development of normal FNA and reduce susceptibility to CAI among male elite youth soccer players. Research supporting these recommendations has not yet been conducted and is another possible area of focus for future research.

Conclusion

Increased FNA is more common and FNA is greater in male elite youth soccer players with CAI than in those without CAI. FNA angle was a significant predictor of CAI in male elite youth soccer players. Furthermore, male elite youth soccer players with CAI were found to have isometric strength deficits in the ankle evertor and hip abductor muscles. Clinical evaluation of FNA in male elite youth soccer players should be included in screening programs to identify those at risk for CAI. Moreover, ankle evertor and hip abductor muscle strength should have greater importance in the CAI preventive programs planned for male elite young soccer players with increased FNA.

Abbreviations

CAI

Chronic ankle instability

FNA

Femoral neck anteversion

IBM

International Business Machines

MVIS

Maximum voluntary isometric muscle strength

ROM

Range of motion

SPSS

Statistical Package for the Social Sciences

Authors’ contributions

All authors contributed to the design, conceptions and implementation of the study. Data collection were performed by all authors. Data analysis was performed by Osman Coşkun, Gökmen Yapalı, Tuğba Arslan, Serdar Arslan. Serdar Arslan wrote the frst draft of the manuscript, and research process supervision and manuscript proofreading were carried out by Osman Coşkun, Serdar Arslan and Engin Dinç. All the authors have read and approved the fnal manuscript.

Funding

There is no funding source.

Data availability

The datasets used for analysed during the current study are available from the corresponding author upon reasonable request.

Declarations

Conflict of interest

The authors declare that they have no conflict of interest.

Ethical approval

The research was carried out by the Declaration of Helsinki and received ethical compliance according to the decision numbered 2022/20–157 and dated 02/03/2022 from Health Sciences Scientific Research Ethics Committee of Necmettin Erbakan University.

Informed consent

All participants were informed about the study and Declaration of Helsinki; after that, written informed consent was signed.