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Determination and Significance of

Femoral Neck Anteversion

Femoral neck anteversion (FNA) describes the normal torsion or twist present in the femur. Femoral neck anteversion is defined as the anglebetween an imaginary transverse line that runs medially to laterally through the knee joint and an imaginary transverse line passing

through the center of the femoral head and neck (Fig. 1).1,2 In adults without pathology, the femur is twisted so the head and neck of the femur are angledforward between 15 and 20 degrees from the frontal plane of the body.1,2 Insome instances, the FNA angle is directed forward or backward well beyondthis angle. Some researchers3–8 suggest that FNA angles outside this 15- to20-degree average are a contributing factor in many different orthopedicproblems in the lower extremity that are commonly seen by physical therapists.The purpose of this Update is to describe how FNA is related to hip rotation, how hip rotation range of motion can be used to predict abnormal FNA, and how asymmetries in hip rotation may be used to identify patients who may be at riskfor developing various orthopedic problems in the hip and lower extremity.

Femoral neck anteversion sometimes is called “medial femoral torsion.”2,3 It is

thought to result from medial (internal) rotation of the limb bud in early intrauterine life.3 In postnatal development, a reduction of the FNA angleusually occurs during growth.2,3 In the newborn, the average FNA angle is 31degrees.2 The average FNA angle is 26 degrees by 5 years of age, 21 degreesby 9 years of age, and 15 degrees by 16 years of age.2 The FNA angle,therefore, diminishes about 1.5 degrees a year until about 15 years of age.2 Inthe adult, average femoral head and neck torsion forward of the body’s frontalplane is about 15 degrees, a little less in men (less than 15°) and a little morein women (18°) (Fig. 1).2,4 Femoral neck anteversion angle is typically symmetrical from the left side to the right side.5

In contrast to FNA, femoral neck retroversion is present when the head and

neck of the femur are angled less than the average FNA angle (15°–20°) alongthe frontal plane of the body (Fig. 1).6,7 In some cases, the femoral head andneck may even be angled backward from the frontal plane of the body.

[Cibulka MT. Determination and significance of femoral neck anteversion. Phys Ther . 2004;84:550–558.]

Key Words: Femoral neck anteversion, Femoral neck retroversion, Hip rotation, Medial femoral torsion.

Michael T Cibulka

550 Physical Therapy . Volume 84 . Number 6 . June 2004

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How FNA Develops What stimulates the femur to undergo torsion or twist isnot understood. The current opinion is that the femurtwists from torsional forces applied perpendicularly tothe epiphyseal growth plate.9 According to the Heuter- Volkmann Law of epiphyseal pressure, increases in pres-sure across the epiphysis will decrease its growth, whereas decreases in pressure will increase its rate of growth.8 In adults, the epiphysis is closed and theHeuter-Volkmann Law cannot explain bone remodel-ing. Wolff ’s Law explains the remodeling or change inadult bone. Wolff ’s Law states that every change in theform and the function of a bone is followed by changesin the bone’s internal and external architecture inaccordance with mathematical laws.8,9 Remodeling of the FNA also may occur because of changes in the stressplaced on the adult femur’s diaphysis by torsional forces.

What creates torsional force on the femur? Muscle, by either its passive elastic connective tissue or its contrac-tile force, contributes the greatest stress on bones.9

Animal studies10–13 suggest that uneven forces, either by maintaining the hip joint in medial or lateral (external)rotation or by resecting the hip rotator muscles, canproduce changes in the FNA angle. Bernbeck,11 Salter,12

and Wilkinson13 showed that, when the hind limbs of animals were held fixed in lateral rotation, the FNA angle decreased, whereas when the hind limbs werefixed in medial rotation, the FNA angle increased.

Unilaterally resecting the hip medial or lateral rotatorsalters the torsional muscular forces acting on the femur.Haike10 has shown that increased or decreased femoralanteversion resulted after resecting either the medialrotator or the lateral rotator muscles of the hip.

Published reports1,3–5 have suggested that habitual sleep-ing and sitting postures, in which the hip is held at ornear the end of medial or lateral rotation, may producechanges in the FNA angle. These extreme postures often will produce an increase in hip rotation in one direction, with a corresponding decrease in hip motion in theopposite direction. As expected, hip joint motionincreases in the direction the hip is held. Habitually adopting a sleeping or sitting position in which the hipis held in extreme lateral rotation, therefore, favors an

increase in lateral rotation motion with an equal loss of medial rotation (Figs. 2 and 3). Maintaining an extremehip posture also produces changes in the soft connectivetissue surrounding the hip, shortening the hip joint capsule and muscles on one side and lengthening thehip joint capsule and muscles on the other side. Theseasymmetrical changes in soft tissue around the hip likely will create uneven torsional forces placed on the femur.

Examination of children with hemiplegia also lendssupport to the theory that changes in hip muscle forceare related to an abnormal FNA angle. Staheli et al14

looked at the hips of children with hemiplegia andfound that the FNA angle on the nonhemiplegic side isnormal, whereas the FNA angle was increased on thehemiplegic side, as was the motion of medial rotation when compared with the normal side.

MT Cibulka, PT, MHS, OCS, is Physical Therapist and Owner, Jefferson County Rehab & Sports Clinic, 1330 YMCA Dr, Ste 1200, Festus, MO

63028-2647 (USA) ([email protected]).

An increased or a decreased femoral

neck anteversion angle has been

linked to many different lower-

extremity problems.

Physical Therapy . Volume 84 . Number 6 . June 2004 Cibulka . 551

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Measuring the FNA Angle Using ImagingTechniques Although FNA was anatomically described as early as the19th century, the first method used to measure FNA wasthe biplane radiograph. Perhaps the most often usedtechnique is the method described by Magilligan in1956.15 The Magilligan method consists of taking an

anteroposterior radiograph and a true lateral radio-graph of the hip and an anteroposterior radiograph of the knee. Three lines are used to determine the FNA angle—the long axis of the femur, the axis of thefemoral neck, and the axis of the knee. The long axis of

the femur is defined as a line that connects 2 points—thecenter of the base of the knee and the center of the baseof the femoral head. The axis of the femoral neck is definedby a line drawn from the center of the femoral head tothe center of the base of the femur. The axis of the knee isa line drawn from the medial to the lateral posteriorfemoral condyles. The angle formed between the axis of

the femoral neck and the axis of the knee is measured(Fig. 4). Given this angle, the true angle of torsion isthen derived from a graph produced by Magilligan.15

Other researchers16–18 have modified this techniqueslightly over the years.

Most femoral torsion problems are evaluated with com-puterized tomography (CT). The method described by Murphy et al18 is often used, with slight variationsdescribed by others.19–22 This CT technique involves 3images or scans—2 proximal and 1 distal. Murphy ’smethod is based on strict geometrical reconstruction of the angle of anteversion. The patient is positioned in thescanner so that the long axis of the femur is parallel tothe long axis of the scanner. One image defines thelocation of the center of the femoral head, the secondimage defines the base of the femoral neck, and thethird image defines the distal femoral condylar axis(Fig. 4). The angle in the transverse plane between theintersection of the plane of anteversion and the condylarplane defines the angle of anteversion. Murphy et al18

showed the accuracy of CT by comparing CT measure-ments with direct measurements of 32 dried femoralbone specimens that were used as a gold standard.Murphy et al18 found that measuring anteversion with

computerized tomography was accurate within 1 degree when compared with measuring the femoral bone spec-imens directly.

A Clinical Method to Determine the FNA AngleThe idea for using passive hip rotation to determineabnormal femoral torsion arose from observations of

children who had an in-toeing or out-toeing posture orgait. In 1957, Sommerville23 reported that extreme dif-ferences between hip medial and lateral rotation arerelated to femoral torsion problems in children. Crane1

found that differences between hip medial and lateralrotation were associated with change in FNA and withthe toeing-in and toeing-out of the lower extremity.Crane also discovered that children who toe-out had alow FNA angle and had medial rotation of the hip of 20degrees or less, whereas lateral rotation exceeded 60degrees. Those children with a high FNA angle hadmedial rotation of the hip exceeding 60 degrees andlateral rotation less than 30 degrees, and they tended totoe-in.

Early observations of children who toed-in or toed-out suggested that passive hip rotation could be used clini-cally to predict an abnormal FNA angle in children. Few studies have looked at the relationship between the FNA angle and passive hip rotation in adults. In 100 adult subjects, Braten et al24 observed that the FNA angleincreased as medial rotation increased and lateral rota-tion decreased. Because subjects without impairments were used, differences were small but significant. Tonnisand Heinecke25 examined 152 adult patients and also

found that hip rotation was related to the FNA angle.Patients with greater lateral rotation than medial rota-tion had femoral neck retroversion, whereas those withgreater medial rotation than lateral rotation had FNA.25

Although the hip motion and the FNA angle weresmaller in the group of adults than in the group of children, the FNA angle still correlated well with thedifference between medial and lateral rotation of the hipin both groups.25

A limitation in using passive hip rotation to determinethe FNA angle is that a precise FNA angle cannot be

determined from clinical measurements. A precise FNA angle, however, is only needed in the selection of patients and preoperative planning for a derotationosteotomy of the femur.5,6,8 Because physical therapistsdo not perform femoral neck operations, determining aprecise FNA angle is not of vital importance. Determin-ing the existence of an abnormal FNA angle is of potential importance to physical therapists when dealing with patients with lower-extremity orthopedic problemscommonly related to increased or decreased FNA.24,26–29

Because studies show that the FNA angle appears closely linked to differences between hip medial and lateral rota-

Figure 1.Illustration of normal, increased, and decreased femoral neck anterver-sion (FNA) angle.

552 . Cibulka Physical Therapy . Volume 84 . Number 6 . June 2004

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tion, I suggest that physical therapists use this informationto predict when an abnormal FNA angle might exist.

Researchers have attempted to determine the upper andlower limits for normal hip rotation. Most clinical studiesmeasured hip rotation in the prone position with hipsextended and knee flexed to 90 degrees.26,30–38 Thepelvis is stabilized, and the hip medially or laterally rotated by grasping the ankle. When a firm end point isreached, the hip angle is measured. Studies performedon subjects without impairments26,33 have consistently shown that hip rotation is consistently equal from theleft to right sides, especially when looking at a specificmotion such as medial rotation. Differences in hiprotation between the left and right side rarely exceed 10degrees (Tab. 1).30 The mean difference in hip rotationin adults between the left and right sides is about 8degrees (Tab. 1). Using a cutoff of 2 standard deviationsabove or below the mean (a common method used toidentify the upper and lower limits of abnormality in anormally distributed measure), an abnormal motionexists when left and right measurements are morethan 16 degrees apart in an adult. For example,

findings of 40 degrees of left hip medial rotation and60 degrees of right hip medial rotation would beconsidered abnormal.

In patients with suspected abnormal FNA, observing thedifference between the left and right sides for a specificmovement such as hip medial rotation is not as impor-tant as observing the difference in motion betweenmedial and lateral rotation of the hip on one side.Studies that have examined hip motion on subjects without impairments have found only small differencesbetween medial and lateral rotation. Svenningsen et al26

examined children and adults without impairments andfound the greatest disparity between hip medial rotationand lateral rotation (Tab. 1). Svenningsen and col-leagues found that medial rotation exceeded lateralrotation by 2 to 16 degrees, with the greatest differencesoccurring in the 4- and 6-year-old groups. Staheli andcolleagues’ examination of children without impair-ments31 showed that females had little differencebetween medial and lateral rotation of the hip, whereasmales had differences ranging from 3 to 11 degrees, withmedial rotation exceeding lateral rotation (Tab. 1). Inadults, Staheli et al,31 Roaas and Andersson,33 Ellisonand colleagues,35 and Chesworth et al36 found little

Figure 2.Sitting in the “W” or reverse tailor position with maximum hip medialrotation.

Figure 3.Sitting in the tailor position with maximum hip lateral rotation.


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difference between medial and lateral rotation of thehip, ranging from as little as 1 to 5 degrees of difference.

Studies That Examined the RelationshipBetween FNA and Passive Hip RotationHip rotation often is used to estimate FNA in clinicalsettings.39 Recent studies24,26–29 have shown that the FNA angle, measured radiographically using the methoddescribed or adapted by Magilligan, is related to thedifference between medial and lateral rotation of thehip. In most studies, hip rotation was measured with thesubjects positioned prone, with the hip extended andthe knee flexed to 90 degrees. Patients with a high FNA angle tended to have more medial rotation of the hipand less lateral rotation of the hip (Tab. 2). In contrast,patients with a low FNA angle tended to have morelateral rotation of the hip and less medial rotation of thehip. Total hip rotation usually remained the same. Only in a study by Gelberman et al40 did some patients exhibit a complete reversal in how the hip was limited. In that study, the patients’ hips showed an increase in medialrotation and less lateral rotation in the fully extended0-degree position, whereas the motion was reversed when the hips were flexed.

The finding of diminished lateral rota-tion with increased medial rotation anda large FNA angle also is consistent withmany clinical observations.1,3–5,8 A trade-off in medial and lateral rotationof the hip appears to occur—as onemovement or direction increases, the

other usually decreases— while the totalhip motion remains equal. For exam-ple, as medial rotation increases, lateralrotation usually decreases. The resultsof the study by Swanson et al8 suggest that femoral torsion deformity exists when medial rotation exceeds lateralrotation by more than 30 degrees andthat an abnormal FNA exists when lat-eral rotation exceeds medial rotationby more than 30 degrees.

A Clinical Test to Accurately Determine FNA?Two groups of investigators30,38 have studied the tro-chanteric prominence angle test (TPAT) or Craig test,and the reports show conflicting data on the validity of measurements this test provides. In 1992, Ruwe et al30

evaluated FNA preoperatively in 59 patients (91 hips),and based on their findings, they claimed that the TPATcan be used to accurately and validly measure the FNA angle of the femur. Femoral neck anteversion was deter-mined at the time of the operation by Magilligan radio-graphs and by CT scanning using the Murphy technique.The FNA values were then compared with the clinicalTPAT measurements. The TPAT was performed with the

patients lying prone. The examiner palpated thepatients’ greater trochanter with one hand while pas-sively rotating the hip with the other hand. The accuracy of TPAT depends on having the greater trochanter at itsmost laterally prominent position— with the femoralneck axis parallel to the condylar axis at the knee. Theamount of hip medial rotation when the greater tro-chanter is at its most laterally prominent position, there-fore, should equal the FNA angle. The reliability of theTPAT measurements was not assessed. Ruwe and col-leagues30 showed that the TPAT predicted the FNA,measured intraoperatively, more accurately than either

the CT or Magilligan method. The mean differencesbetween direct clinical measurements and those deter-mined by intraoperative measurements were 4.1 degrees(SD3.2) on the left (Pearson r .88) and 3.5 degrees(SD3.9) on the right (Pearson r .93). The differencesbetween measurements obtained from the Magilliganradiographs and measurements found on operation were 9.5 degrees (SD9.1) on the left side and 9.6degrees (SD8.4) on the right side.

Davids et al38 studied the TPAT on 20 children withcerebral palsy. Davids et al used a retrospective case

Table 1.Hip Rotation Medial Rotation/Lateral Rotation (SD)a

Study

Age (y)

Adults4 6 8 11 15

Svenningsten et al34

Males 51/48 51/47 51/42 46/42 41/43 38/43 (8)

Females 60/44 58/44 57/43 50/42 48/42 52/41 (8)Roaas and Andersson33

Males * * * * * 32/34 (8)

Ellison et al35 * * * * * 38/36 (11)

Staheli et al31

Males 42/45 52/44 51/40 45/38 46/38 40/38 (8)Females 43/45 44/42 40/40 42/38 39/39 33/38 (8)

Chesworth et al36 * * * * * 43/42 (9)

a Asterisk indicates not measured. SDstandard deviation.

Figure 4.Illustration showing “cuts” used to determine the femoral neck anterver-sion angle using computerized tomography scan.


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series design to show the relationship between the TPATand a modified Murphy CT analysis performed beforesurgery. No data on tester reliability were given. Davids

et al concluded that the TPAT performed poorly by either overestimating or underestimating FNA by morethan 5 degrees in 24 hips and by more than 10 degreesin 14 hips. They also concluded that the application of the TPAT is restricted by variable anatomy and soft tissue, especially in patients who are obese. As notedpreviously, for the TPAT to be accurate, the tangent tothe most prominent portion of the greater trochantermust be perpendicular to the axis of the femoral neck;however, Davids et al rarely found this to be true andnoted considerable variability in the children with cere-bral palsy they studied (Tab. 3). With only 2 studiesperformed on the TPAT, additional research is neededto determine whether this test can accurately predict theFNA angle. Because physical therapists do not need aprecise FNA angle measurement, I believe either theTPAT or passive hip rotation values can be used to helppredict FNA.

The Clinical Importance of Increased orDecreased FNA An increased or decreased FNA angle has been associ-ated with a variety of lower-extremity problems in new-borns, children, and adults. The interest in determiningthe precise FNA angle began in the early 20th century

with the observation that newborns with congenital hipdislocation often had an increased FNA angle.1,3,5,6,8

Soon after, children with an in-toeing or out-toeing gait

were noted to have an increased or decreased FNA angle.1–7,9 Excessive in-toeing or out-toeing has beenshown to be related to many different compensatory problems of the lower extremities, including tibialtorsion, genu valgum, genu valgus, pes planus, pesequinus, and metatarsus varus.1–6,8,23 Many otherstudies1,3–8,14,23,25,28,29,31,41–49 have shown the relation-ship between an increased or decreased FNA angle andother orthopedic problems of the lower extremity.

Gelberman et al29 showed that a diminished FNA anglein adolescents is often associated with slipped capitalfemoral epiphysis of the hip. The FNA angle in patients with slipped capital femoral epiphysis was 1 degree(normal FNA angle15°–20°) in the worst cases and 2.5degrees in more moderate cases.29 Alterations in thealignment of the proximal part of the femur have beenconsidered capable of redistributing the forces that areapplied across the proximal femoral epiphysis. Gelber-man and colleagues29 suggested that the forces that tendto cause a slipped capital femoral epiphysis act in thesame direction as the forces that are responsible for thephysiological decrease in the angle of anteversion dur-ing growth. Decreased FNA or hip retroversion cancreate unequal force distribution on the proximal fem-

Table 2.Studies That Examined the Relationship Between Femoral Neck Anteversion (FNA) and Passive Hip Rotation a

Study N Age (y) MR LR FNA e-FNA

Svenningsen et al26 30 7 (4–10) 74 (6.8) 19 (7.2) 42 (5.5) 2330 10 (7–13) 60 (7.2) 27 (7.8) 36 (6.3) 2030 16 (15–21) 53 (8.5) 37 (5.9) 28 (8.4) 16

Kozic et al27

MRLR 1,030 8–9 44 43 24 (4.3) 24MRLR 86 8–9 65 30 36 (7.3) 24LRMR 24 8–9 23 58 14 (7) 2

Reikeras and Bjerkreim28

1st exam 24 7.7 (6–9) 78 (8) 16 (8) 47 2416 7.3 (6–8) 76 (10) 28 (10) 45 24

2nd exam 24 16.5 (14–18) 52 (12) 43 (10) 30 1516 15.7 (14–16) 63 (11) 30 (10) 31 15

Control 26 16.3 (14–19) 50 (9) 41 (8) nm 15

Study N Age (y) MR 1 MR 2 LR 1 LR 2 FNA e-FNA

Gelberman et al29

MRLR 16 5.2 (5.1) 80 (5) 78 (5) 10 (5) 45 (13) 49 (10) 26LRMR 8 5.5 (5.5) 71 (4) 46 (7) 18 (7) 32 (6) 32 (6) 26

MRLR 20 5.1 (5.2) 51 (8) 50 (7) 54 (9) 55 (9) nm 26

Braten et al24

IRER 100 35 (16–65) 48 (10) 36 (8) 38 (7) 43 (9.6) 18/14 18/14

a MR hip medial rotation, LR hip lateral rotation, e-FNA expected FNA angle for age using data from study by Fabry et al,2 nmnot measured. Standard

deviations or ranges of values are shown in parentheses. In study by Reikeras and Bjerkreim, 28 one control group and one time-series group were examined twice.

In study by Gelberman et al,29 hip MR and LR were measured with hip extended and with hip flexed to 90 degrees. In study by Gelberman et al, superscript 1

measurements were taken with the hip extended to 0 degrees, and superscript 2 measurements were taken with the hip flexed to 90 degrees. In study by Braten

et al,24 superscript 1 measurements are for female subjects, and superscript 2 measurements are for male subjects.


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oral epiphysis. Some adolescents may be unable to resist the physiological shearing forces across the epiphysisresulting in a slipped capital femoral epiphysis. A decreased FNA, therefore, has been proposed to be afactor in developing slipped capital femoral epiphysis.29

More research is needed.

Studies7,25,46,47 also have shown that an increased ordecreased FNA angle is associated with degenerative hip joint disease. Tonnis and Heinecke7,25 have shown therelationship between reduced FNA (femoral neck retroversion) and degenerative disease of the hip. They defined abnormal FNA using 4 grades, assuming that anormal FNA angle is between 15 and 20 degrees. Mod-

erately decreased FNA was defined as an angle between 10and 14 degrees. Severely decreased FNA was defined as anangle less than 10 degrees. Moderately increased FNA wasdefined as an angle between 21 and 25 degrees. Severely

increased FNA was defined as an FNA angle greater than25 degrees.25 Tonnis and Heinecke25 looked at the FNA angle in 118 patients who had arthritis of the hip. Passive

hip rotation also was measured. They found decreasedhip medial rotation and increased lateral rotation wererelated to diminished FNA. For example, patients whohad a severely decreased FNA angle (less than 10°) hadan average range of 17 degrees of medial rotation and anaverage external rotation of 40 degrees. Tonnis andHeinecke25 found that patients who had decreasedFNA angles also were more likely to have osteoarthritisof the hip.

Changes in femoral anteversion that result in anincreased or decreased FNA angle can alter the congru-ence of the hip joint.25 A change in acetabular antever-sion also can alter the congruence of the hip joint.50 Hip joint incongruence is the most commonly cited cause of osteoarthritis in the hip joint.25,48,50 The congruity of thehip joint depends on the relationship between FNA andanteversion of the acetabulum.25 A change in hip anteversion requires a similar adjustment in the acetabulumto keep hip joint congruity.

A diminished FNA angle has been associated with a tornacetabular labrum of the hip.49 Ito and colleagues49

studied 24 patients with hip pain and evidence of a labraltear of the hip, and they showed that the patients with

labral tears had a mean reduction in the FNA angle.Their data showed the mean FNA angle in patients withlabral tears was 9.7 degrees compared with 15.7 degreesin patients without impairments.49 Hip rotation was not measured in this study. Ito and colleagues49 suggestedthat repetitive impingement of the acetabulum caninjure the labrum when a hip with decreased femoral joint anteversion changes the head and neck angle of the femur. Reduced surface area in the hip results inincreased force on the acetabular labrum, which may predispose the labrum to injury. Moreover, a torn ace-tabular labrum is thought to be a precursor to degener-

ative hip joint disease.49

Thus, an increase or decrease inthe FNA angle that may alter the hip’s congruity willplace abnormal stress on the acetabular labrum andpossibly lead to injury.

Conclusion Assessing passive hip medial and lateral rotation can bea useful guide in determining if an increased ordecreased FNA angle exists. An increased or a decreasedFNA angle has been linked to many different lower-extremity problems, including osteoarthritis of the hip,coxa plana, slipped capital femoral epiphysis, congenital

Table 3.Data From the Study by Davids et al38 on the TrochantericProminence Angle Test (TPAT)a

PatientNo.

Age(y) Sex Side

FNA Angle(°)b

TPAT(°)c

1 12 M R 19 20

L 35 40

2 12 F L 53 35

3 14 M R 30 15L 47 20

4 9 F L 43 50

5 8 F R 44 55L 48 60

6 8 M L 29 35

7 10 M R 39 30L 37 40

8 13 F R 40 40L 34 60

9 10 M L 50 50

10 13 F R 67 40L 57 40

11 10 M R 16 5

12 13 M R 46 30L 53 25

13 10 F R 55 30L 30 20

14 8 F R 24 30L 28 45

15 10 M R 39 40L 34 25

16 15 F R 34 30L 33 20

17 10 M R 24 20L 27 20

18 13 M R 12 20L 44 35

a Mmale, Ffemale, R right, Lleft.b FNA femoral neck anterversion (measured with biplane radiography).c TPAT was measured with subjects positioned prone.


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hip dysplasia, acetabular labral tears, and in-toeing andout-toeing of the lower extremities.1,3–8,14,23,25,28,29,31,42–49

Identifying when an increased or decreased FNA angle ispresent may help physical therapists recognize patients who may be at risk for developing hip or other problemsassociated with in-toeing or out-toeing. Moreover, asym-metries in hip joint rotation also have been associated

with low back and regional pain in the sacroiliac joint.43,51

Because the difference between medial and lateral rota-tion of the hip are related to the FNA angle, I believethat physical therapy interventions aimed at restoringsymmetry in hip motion is a reasonable approach intrying to manage hip problems. Differences greater than16 degrees between the left and right sides for a specificmovement or differences of more than 30 degreesbetween hip medial and lateral rotation on one side may help physical therapists identify patients who may develop future hip or lower-extremity problems associ-ated with in-toeing or out-toeing. Physical therapists alsoshould consider factors that may contribute to differ-ences in hip medial and lateral rotation. For example,sitting or sleeping postures where the hip is habitually placed in extreme hip rotation may change muscle and joint capsule length (Figs. 2 and 3). Although there areno studies on restoring hip motion symmetry and theFNA angle, I believe these studies would be beneficial,because restoring motion and muscle force is an impor-tant part of physical therapist practice.

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