Long-Term Outcome of Idiopathic Increased Femoral Anteversion in 58 Untreated Individuals at a Mean Age of 46.2 Years

Abstract

Background:

Increased femoral anteversion is a common problem in children, but the condition usually normalizes spontaneously over time. There is limited knowledge of the long-term consequences of persistently increased anteversion. The purpose of this study was to analyse the long-term functional complaints of untreated adults with idiopathic increased anteversion compared with a control group.

Methods:

Study participants were recruited from our institutional register of increased femoral anteversion during the period 1975 to 2008. Inclusion criteria were anteversion angle ≥30 degrees and no other disorders affecting the lower limbs. Outcome measures were the HAGOS and KOOS questionnaires, radiographic signs of osteoarthritis, and clinical examination. A control group of 24 healthy individuals was examined with the same methods.

Results:

Fifty-eight patients (46 females) with a mean age of 46.2 years were included in the AV group. The mean anteversion angle was of 40.2 degrees in the anteversion group and 20.6 degrees in the controls. The mean external foot progression angle was 0.5 degrees in the anteversion group and 4.6 degrees in the controls (P <0.001). The anteversion group scored significantly worse than the control group in 5 out of 6 HAGOS subscales: Pain (P=0.032), Symptoms (P=0.041), Sport/Rec (P=0.001), PA (P=0.036), and QOL (P=0.001). The KOOS subscale Symptoms was the only subscale with a worse score in the AV group (P=0.006). Only 1 patient in the anteversion group had hip osteoarthritis.

Conclusions:

Untreated adults with idiopathic increased femoral AV at a mean age of 46 years experienced more hip pain and limitations in participation in physical activities and sports compared with healthy individuals, but the limitations were mostly small to moderate and would hardly influence the present strict indications for surgical correction in children.

Level of Evidence:

Level II—prospective comparative study.

Intoeing is a common condition in children and adolescents. It is most frequently caused by increased femoral anteversion (AV).^1–4 Femoral AV is defined by the angle of the femoral neck in relation to the femoral condyles in the transversal plane. The degree of AV is greatest in infancy and gradually decreases towards skeletal maturity, from a mean of 35 degrees at birth to ~15 degrees in adults.^5,6 This indicates that increased AV usually is self-correcting.

Patient-reported outcome measures (PROMs) have shown that increased femoral AV in children and adolescents is associated with pain and functional challenges, including impaired gait, higher frequency of falling, and increased fatigue.^7–9 In the general population, about one-third of children and adolescents at the age of 4 to 18 years reported limb pain, but no distinction between lower limb pain and upper limb pain was performed.^10,11 This indicates that hip and knee pain is quite common and multifactorial, making it difficult to identify individuals who most likely would benefit from treatment. Many children with increased AV are symptomatic. However, we do not know whether pain and other impairments will disappear, increase, or remain unchanged later in life, because there seems to be no long-term studies using PROMs to explore the natural course of increased AV in adults.

The only documented effective treatment of increased AV is femoral derotational osteotomy (FDO) to correct the bony deformity. There is, however, no consensus based on the degree of anteversion regarding the indications for surgery. According to recent review articles, surgery should be suggested only in symptomatic cases, after the age of 10 years, and when the measured AV angle is above 25 to 50 degrees.^12–14 Regarding the effects of corrective FDO for increased AV, no long-term studies using PROMs have been published. However, with a follow-up of only 1 year, significant improvements in both lower limb function and pain scales were reported.^9,15 There are divergent opinions about the possible association between increased AV and later hip osteoarthritis (OA), but no long-term radiographic evaluation of OA in adults with increased AV has been performed.

Correct indications for surgery can hardly be established until the natural history of untreated increased AV has been explored. Therefore, the aims of this study were to analyze the long-term functional complaints in nonoperated individuals with idiopathic increased femoral AV compared with a control group with normal AV. Other aims were to examine whether increased AV is correlated with OA of the hip and knee joints. We hypothesized that individuals with increased AV have a less satisfactory functional outcome regarding PROs (pain and lower limb function), compared with a control group.

METHODS

Study participants were recruited from our institutional registry of pediatric patients. The reason for the initial orthopaedic referral was intoeing. They were evaluated for increased femoral AV during the period 1975 to 2008 who had not been surgically treated (“wait and see” policy). All participants were younger than 18 years at the time of initial referral. Initial radiographic evaluation during childhood had been done either by conventional radiographs using the Rippstein method (53 participants) or CT measurements (5 participants). Radiographs for measurement of tibial torsion had not been taken at the initial evaluation. For the present study, each participant underwent CT measurements for confirmation of the femoral AV angles before inclusion. Patients with AV angles ≥30 degrees at that time were asked to participate in the current study.

Inclusion criteria for our long-term follow-up study were: persistently increased AV angle ≥30 degrees as confirmed by new CT measurements at the time of enrollment into the study, and no surgical treatment for any torsional deformity in the lower limbs. Exclusion criteria were: AV angle <30 degrees, developmental dysplasia of the hip, or other hip or knee disorders. In addition, we reviewed all available radiographs for each participant and excluded those in whom acetabular dysplasia was identified.

One hundred forty-two individuals were found eligible for inclusion and 70 accepted the invitation after written consent. Fifty-eight individuals (46 females) had AV angles >30 degrees bilaterally (N=46) or unilaterally (N=12) and were enrolled in the study (AV group). A subgroup analysis was done, comparing subjects with AV angle 30 to 39 degrees (high AV subgroup) and those with AV ≥40 degrees (excessive AV subgroup) to explore any possible effects of different AV levels.

Our control group included 33 healthy individuals (27 females) with no history of hip or groin pain. The controls were prospectively recruited during the same period as the study participants. They were matched for age and sex and randomly selected from hospital staff and residents of Oslo. All controls underwent the same examinations as those performed in the AV group. Nine of the controls were excluded due to AV angle ≥30 degrees. Thus, the final control group consisted of 24 individuals.

Clinical Evaluation

Passive range of motion of the hips and knees was measured with a goniometer. Hip internal rotation (HIR) and hip external rotation (HER) were measured in the prone position with the knees flexed to 90 degrees.

Zebris FDM gait analysis system, model FDM 1.5, (Zebris Medical GmbH, Isny, Germany) was used to obtain the foot progression angle (FPA) in stance (positive values, outward rotation). The participants walked barefoot at self-selected speed for 30 seconds. The gait plate recorded each step by the heel, midfoot, and forefoot positions at midstance and calculated the FPA for each foot.

Radiographic Examinations

Measurements of Anteversion and Tibial Torsion

Radiographs from the initial examination in childhood were obtained in all the participants. The femoral AV angles had initially been measured by the biplanar method of Rippstein.¹⁶ For the present study, each participant underwent CT measurements for confirmation of the femoral AV angles, using the method of Murphy.^17,18 The CT examination was performed with a Siemens Somatom Force (Siemens Healthcare GmbH, Erlangen, Germany). With a single slice technique, 2 axial slices of 4 mm thickness each were obtained: one through the center of the femoral head and one just above the lesser trochanter. The 2 images were combined by the CT machine software (Fig. 1B). An axis from the center of the femoral head to the center of the distal femoral neck was drawn (Fig. 1B). The femoral AV angle was calculated as the angle between the femoral head-neck axis and the posterior tangent of the femoral condyles in the transverse plane. The anteversion angle of the acetabulum (acetabular AV) was measured using the method of Reikerås,¹⁹ as the angle between a line connecting the anterior and posterior border of the acetabulum and the transverse axis of the pelvis (Fig. 1A). Tibial torsion (TT) was defined as the angle between a line through the center of the medial and lateral ankle malleoli and the posterior tangent of the 2 femoral condyles in the transversal plane (Fig. 1B, C) (positive values, external torsion). All CT measurements were performed by the same senior consultant radiologist with >30 years of clinical experience. The sum of acetabular AV and femoral AV defines the McKibbin index. The range 20 to 50 degrees is considered normal.²⁰ This is based on the sum of the upper limits for femoral AV (25 deg.) and acetabular AV (25 deg.). We defined increased femoral AV >30 degrees and therefore defined the upper limit to be 55 degrees. Thus, increased McKibbin index was defined as the combination of femoral AV >30 degrees and acetabular AV >25 degrees.

FIGURE 1.

Schematic drawings of the 3 different methods that were used for CT-based measurement. A, Acetabulum anteversion, defined as the angle between a line connecting the anterior and posterior border of the acetabulum and the transverse axis of the pelvis. B, Femoral anteversion, defined as the angle between the femoral head-neck axis (red line) and the posterior tangent of the medial and lateral femoral condyles in the transverse plane (blue line). B and C, tibial torsion, defined as the angle between a line through the center of the medial and lateral ankle malleoli (red line) and the posterior tangent of the femoral condyles in the transversal plane (blue line).

Radiographic Assessment of Hip and Knee Osteoarthritis

Conventional anteroposterior (AP) radiographs of the pelvis were taken with the patients in the supine position. For the knees we obtained standing AP and lateral radiographs. The Syna-Flexer frame (Synarc Inc, Newark, CA) was used for standardized fixed flexion position of the AP knee view (20-deg. flexion and 5-deg. external foot rotation). For the hips and tibiofemoral joints, OA was assessed by the minimum JSW (joint space width).²¹ Minimum JSW was measured at the narrowest part of the upper, weight-bearing part of the hip joint and the smallest JSW of the anteroposterior knee joint. JSW $\le$ 2.0 mm was defined as OA. Patellofemoral joint arthritis was not a part of our study design.

Patient-Related Outcome Measures (PROMs)

To obtain PROMs, the Copenhagen Hip and Groin Outcome Score (HAGOS) and the KOOS (Knee injury and Osteoarthritis Outcome Score) questionnaires were used. The HAGOS questionnaire is validated to assess hip and groin pain in young to middle-aged persons and consists of 6 subscales and 37 items.²²

The KOOS questionnaire contains 5 subscales with 42 items.²³ For both the HAGOS and the KOOS all items were scored 0 to 4, and the subscale scores were transformed to a 0 to 100 scale where 0 points means extreme problems and 100 points means no problems.

Statistics

SPSS (version 28) was used for statistical analysis (IBM, Armonk, NY). Categorical data were analyzed with the Pearson χ² test. Continuous variables were analyzed using the t test for independent samples with Bonferoni-corrected P-values. The correlation between continuous variables was expressed as Pearson correlation coefficient (r). All tests were 2-sided. Differences were considered significant when the P-value was <0.05.

Ethics

Ethical approval was granted by the Regional Committee for Medical and Health Research Ethics in Norway (REK South East B 2019/107, date of issue March 11, 2019). The participants gave their written consent before participation.

RESULTS

Patient Characteristics and Clinical Findings

The mean age in the AV group was 46.2 years (range: 21 to 65 y; SD: 8.8). The mean age in the control group was 44.3 years (SD: 8.4). The mean HIR (Table 1) was 60 degrees (range: 36 to 90 deg.) in the AV group and 40 degrees (range: 20 to 55 deg.) in the control group (P <0.001). The mean HER in the AV group was 24.0 degrees (range: 5 to 50 deg.) and 41.6 degrees (range: 25 to 60 deg.) in the controls (P <0.001). The AV group had mean FPA of 0.5 degrees (range: −13.2 to 12.9 deg.), which was significantly lower than the mean FPA in the controls, 4.6 degrees (range: −10.4 to 16.5 deg.). Twenty-one participants, (34 limbs) walked with intoing (negative FPA). This represents 36% of the AV group.

TABLE 1.

Radiographic and Clinical Results

	AV group N=58		Control group N=24
Parameter	Mean	SD	Mean	SD	P	P *
Femoral AV (deg.)	40.2	7.0	20.6	5.6	<0.001	<0.001
Tibial torsion (deg.)	36.9	10.1	33.4	6.9	0.015	0.172
Foot progression angle (deg.)	0.5	4.7	4.6	5.6	<0.001	<0.001
Acetabular AV (deg.)	22.3	7.0	18.8	6.2	0.007	0.201
Hip JSW (mm)	4.2	0.8	4.2	0.8	0.932
Knee JSW (mm)	4.4	0.6	4.7	0.7	0.071
Exernal rotation hip (deg.)	24.0	11.0	41.6	10.1	<0.001	<0.001
Internal rotation hip (deg.)	60.2	11.9	40.3	8.6	<0.001	<0.001

^* P: significance level with Bonferroni correction.

AV indicates anteversion; JSW, joint space width.

Five participants (9%) in the AV group had femoral AV and tibial torsion >2 SD of the control group (>32 and >47 deg., respectively) and were classified as miserable malalignment. They walked with a mean of FPA of 4.8 degrees (range: −1.8 to 12.9 deg.).

Radiographic Examinations

The mean femoral AV angles were 40.2 degrees (range: 30 to 64 deg.) in the AV group and 20.6 degrees (range: 5 to 29 deg.) in the control group (Table 1). The mean acetabular AV was 22.3 degrees (range: 3 to 27 deg.) in the AV group and 18.8 degrees (range: 4 to 30 deg.) in the control group (P = 0.007). An increased McKibbin index (>55 deg.) was observed in 33 (28%). They had a mean McKibbin index of 70.1 degrees (range: 58 to 79 deg.). The mean tibial torsion was 36.9 degrees (range: 11 to 65 deg.) in the AV group and 33.4 degrees (range: 21 to 54 deg.) in the controls (P=0.015).

Correlations between radiographic and clinical variables, examined with Pearson correlation coefficient, are shown in Table 2. Femoral AV was significantly correlated with TT (r=0.26), HIR (r=0.26), and HER (r=−0.41), but not with FPA (r=−0.14) or acetabular AV. TT was significantly correlated with FPA and HER, but not with HIR. FPA was significantly correlated with HIR (r=−0.35), but not with HER. HIR was significantly correlated with HER (r=−0.32). The only significant correlations in the control group were FPA/TT (r=0.42; P=0.004) and HIR/HER (r=−0.32; P=0.029).

TABLE 2.

Pearson Correlation Coefficients (r) Between Clinical and Radiographic Measurements in the AV Group

	Acetabulum AV		Tibial torsion		FPA		HIR		HER
	r	P	r	P	r	P	r	P	r	P
Femoral AV	−0.01	0.926	0.26	0.007	−0.14	0.169	0.26	0.008	−0.41	<0.001
Acetabulum AV			0.05	0.608	−0.01	0.920	0.12	0.245	− 0.17	0.100
Tibial torsion					0.50	<0.001	0.10	0.316	− 0.23	0.020
FPA							−0.35	<0.001	0.11	0.295
HIR									− 0.32	0.001

AV indicates anteversion angle; FPA, Foot progression angle; HER, Hip external rotation; HIR, Hip internal rotation.

Radiographs of the pelvis and knees for evaluation of OA were obtained in patients ≥ 40 years (48 participants, 28 in the AV group and 20 in the control group). The mean JSW of the hips in the AV group was 4.2 mm (range: 2.0 to 6.2 mm); there was no difference between the groups (Table 1). Hip OA was found in one hip in the AV group (JSW=2.0 mm) and none in the control group, whereas knee OA did not occur in any of the individuals.

Patient-Related Outcome Measures

There were significant correlations between all of the HAGOS subscales in the AV group, with correlation coefficients from 0.67 to 0.90. After Bonferroni corrections the participants with increased AV scored worse in all the HAGOS subscales, except HAGOS ADL, compared with the controls (Table 3). The mean HAGOS Pain score was 84.6 points (range: 10 to 100 points) in the AV group and 94.4 points (range: 50 to 100 points) in the control group. There were no significant differences in HAGOS subscale scores between the subgroup of participants with AV 30 to 39 degrees and patients with AV ≥40 degrees (Table 4). No significant correlations were found between patient age or femoral AV angle and any of the HAGOS subscale scores. We explored the proportion of participants in the AV group with abnormally low HAGOS subscale scores, defined as values below the lower limit of normal variation (mean score − 2 SD) of the control group. Using this threshold, the percentage with abnormal scores varied from 11% (ADL) to 33% (QOL), (Table 3).

TABLE 3.

HAGOS Outcome Score

	AV group	Control group		Lower normal limit†	AV group <2 SD, N (%)‡
Outcome variable	N=58	N=24	P *	Points	N=58
Pain	84.6 (18.4)	94.4 (11.6)	0.032	71.2	12 (21)
Symptoms	80.4 (17.5)	91.4 (13.1)	0.041	65.2	11 (19)
ADL	88.5 (15.8)	95.3 (12.4)	0.272	70.5	19 (11)
Sport/Rec	84.1 (18.9)	95.9 (7.7)	0.001	80.5	34 (20)
PA	79.1 (23.1)	91.9 (16.2)	0.036	59.5	14 (24)
QoL	80.3 (20.4)	94.3 (11.6)	0.001	71.1	19 (33)

^* P-values with Bonferroni correction; Values are reported as mean (SD).

^†Lower normal limit, mean – 2 SD of the controls.

^‡Numbers and percentage of the AV group below mean – 2 SD of the controls (95% CI).

ADL indicates activities of daily living; AV, femoral anteversion angle; HAGOS, The Copenhagen Hip and Groin Outcome Score; PA, participation in physical activities; QOL, hip-related quality of life; Sport/Rec, sport and recreation.

TABLE 4.

HAGOS Outcome Score Comparing Patients With Excessive AV (≥40 deg.) and Patients With Increased AV (30 to 40 deg.)

	AV ≥40 deg.	AV 30-40 deg.
Outcome variable	N=36	N=22	P
Pain	83.6 (16.5)	85.7 (21.7)	0.675
Symptoms	78.6 (16.3)	83.1 (19.2)	0.349
ADL	87.7 (14.1)	89.8 (18.4)	0.630
Sport/Rec	81.2 (18.2)	88.4 (19.5)	0.156
PA	79.0 (21.4)	79.4 (25.9)	0.945
QoL	78.7 (19.3)	82.6 (22.2)	0.481

P-values are reported after Bonferroni correction; Values are reported as mean (SD).

ADL indicates activities of daily living; AV, femoral anteversion angle; HAGOS, The Copenhagen Hip and Groin Outcome Score; PA, participation in physical activities; QOL, hip-related quality of life; Sport/Rec, sport and recreation.

Patients with increased McKibbin index (>55 deg.) had reduced mean HAGOS subscales scores, but the differences were not statistically significant different compared with the total AV group.

At the KOOS evaluation (Table 5), the AV group had lower mean scores than the control group, but there were no statistically significant differences in subscales except for KOOS Symptoms after Bonferroni correction. There were no statistically significant correlations between patient age or femoral AV angle and any of the KOOS subscale scores.

TABLE 5.

KOOS Outcome Score

	AV group	Control group		Lower normal limit†	AV group <2 SD, N (%)‡
Outcome variable	N=58	N=24	P *	Points	N=58
Pain	91.0 (13.2)	95.9 (8.1)	0.229	79.8	10 (17)
Symptoms	88.8 (13.8)	96.9 (7.5)	0.006	81.9	13 (22)
ADL	94.7 (8.7)	98.7 (5.7)	0.085	87.3	7 (12)
Sport/Rec	84.3 (23.6)	94.0 (10.5)	0.065	73.0	14 (24)
QoL	84.0 (19.0)	90.9 (14.9)	0.595	61.1	8 (14)

^* P-values with Bonferroni correction; Values are reported as mean (SD).

^†Lower normal limit, mean – 2 SD of the controls.

^‡Numbers and percentage of the AV group below mean – 2 SD of the controls (95% CI).

ADL indicates difficulty during daily activities; KOOS, Knee injury and Osteoarthritis Outcome Score; QOL, Knee-related Quality of Life; Sport/Play, function in sports and play.

The lower limits of normal variation of KOOS were defined as mean subscale score − 2 SD of the control group. In the subscale KOOS Pain, 17% of the individuals in the AV group had a score that was lower than the lower normal limit. In the other 4 subscales, the percentage with abnormal scores varied from 12% (ADL) to 24% (Sport/Play).

Patients with miserable malalignment syndrome (n=5) had a mean HAGOS Pain of 92.8 points (range: 82 to 100 points). The other HAGOS subscales ranged from 86.3 to 94.6 points. The mean KOOS Pain score was 89.7 points (range: 69 to 100 points). The other KOOS subscales scores ranged from 88.2 to 87.7 points.

DISCUSSION

To our knowledge, the current study is the first long-term follow-up of individuals with increased AV. We found increased pain and symptoms in the hip region, hip-related limitations in sports and recreation, and reduced quality of life. Knee pain and other knee-related symptoms and function were comparable to findings in a normal population.

The relationship between increased femoral AV and lower limb function and pain has previously been examined in children and adolescents. Increased AV was associated with hip pain, impaired gait function, higher falling frequency, and reduced participation in physical activities.^7–9 Although our results were significantly worse in the AV group compared with the control group in 5 of 6 HAGOS subscales, the degree of hip complaints seemed moderate, as the scores were within the limits of normal variation in 67% to 89% of the individuals. This indicates that the reduced HAGOS scores are not only statistically significantly different, but also most likely clinically relevant, reflecting reduced ability to participate in sports activities among individuals with increased FA, whereas everyday activities remain unaffected. It remains uncertain whether the reduced function in children improves or remains stationary during adulthood. Our results indicate that the functional complaints hardly deteriorated over the years, as increasing age was not significantly associated with HAGOS subscale scores. However, the mean age was 46 years and further long-term studies of the natural history are needed.

Compared with the control group, the KOOS showed lower subscale scores in subjects with increased AV. However, the differences were usually small or moderate, as the subscale scores were within the normal range in 76% to 88% of the individuals in the AV group. This suggests that adults with increased femoral AV had almost similar knee function as in the general population.

Although the reasons for the functional complaints in individuals with increased AV have not been fully elucidated, it seems probable that they are associated with gait deviations. 3D gait analysis in children and adolescents has shown that increased AV is associated with increased HIR, increased hip flexion and anterior pelvic tilt, and increased knee flexion in terminal stance.^24,25 Increased AV results in a shorter moment arm of the gluteus medius and decreased abductor muscle force.¹³ To increase the abductor force, the subject walks with internally rotated hips, which may lead to an overuse of the abductors and a source of hip pain. This could also lead to a compensatory increased external tibial torsion as indicated in this study and in previous studies.^25,26

Our findings indicated no association between increased AV and radiographic OA as only 1 patient had hip OA. The association between increased AV and OA remains debated. In a systematic review including 1756 patients at a mean age of 60.7 years, the conclusion was: “elevated femoral version may be a risk factor for more severe OA, with or without the presence of concurrent DDH”.²⁶ Other studies concluded that increased AV was significantly associated with the development of hip OA in adults at a mean age of 65 years.^27,28 In contrast, another study found no such association in their study on cadaver femora.²⁹ However, the mean age was 56 years, which was rather low to provide reliable results. The mean age at total hip arthroplasty (THA) is 69 years according to the Norwegian Arthroplasty Register (Yearly report 2023) and 53 years in patients with mild to moderate DDH.³⁰

In a study comparing 5 different methods of measuring AV by CT, it was found considerable differences, depending on the landmarks of the femoral neck axis.³¹ The distal landmark in the femoral neck varied, and the more distal this landmark was defined, the higher was the measured AV angle. The Murphy method used the most distal landmark, just above the lesser trochanter, and therefore, the AV values were highest with this method. The difference between the Murphy values and the other CT methods varied from 3 to 17 degrees. We used Murphy’s method because this modification most closely reflected the anatomic femoral torsion.¹⁸ The mean AV in our control group of healthy adults was 20.6 degrees, and the upper normal limit of normal variation, defined as mean + 2 SD, was 31.8 degrees, which corresponded well with the AV limit of 30 degrees that we used as the dividing line between the 2 groups.

The correlation between AV and HIR was weak (r=0.26) but significant (P=0.008). By using the upper limit of normal variation (mean+2 SD of the control group), we found that 59% of the hips in the AV group had HIR larger than the normal variation. This suggests that HIR is influenced not only by AV but also by other contributing factors.

The control group had a mean FPA of 4.6 degrees, which was similar to that of healthy adults in a previous study.³² The mean FPA in our AV group was 4 degrees lower and was significantly correlated with external tibial torsion, but not with the AV angle. The reason was probably that increased AV and accompanying hip internal rotation were partly compensated by the increased external tibial torsion. The mean tibial torsion was 37 degrees in the AV group and 33 degrees in controls. The latter was similar to 29 to 30 degrees previously reported in normal adults.^33,34

Limitations

This study had several limitations. First, we do not have complete information on how many of the total population underwent rotational osteotomy due to increased AV during the study period. At the time, the original aim was to examine only the nonoperated patients, and thus only these individuals were registered. Second, the control group, composed of 24 randomly selected healthy individuals, was rather small, which could affect the reliability of the statistical analyses and the generalizability of the results. However, the HAGOS scores did not differ much from those in 158 healthy controls in a previous study.³⁵ Third, the AV and TT measurements by CT represent static bony measurements and need supplementary data by 3D gait analysis to evaluate the dynamic effects. Fourth, because of the considerable variation in CT measurements of AV, caution should be exercised when comparing the present results with other studies. Fifth, the limited duration of the FPA examination may prevent detection of variations influenced by walking speed and time duration. Sixth, we did not have the initial tibial torsion measurements, which may have influenced clinical decision-making regarding treatment. Finally, the increased pain in the AV group may have various etiologies; thus, caution is needed, as the study did not establish a direct causal link between increased AV and pain.

CONCLUSIONS

In conclusion, the study showed that adults with untreated idiopathic increased femoral AV at a mean age of 46 years experienced more hip pain and hip-related limitations in sports and recreation compared with healthy individuals without increased AV. The physical limitations were mostly small to moderate and would hardly influence the present strict indications for surgical correction of increased femoral AV.