Congenital Coxa Vara

1. Congenital coxa vara
A Topic Presentation at Amala Institute of Medical Sciences by
Dr. Libin Thomas Manathara

2. TOPICS
• Introduction
• Incidence
• Etiology
• Clinical features
• Radiographic findings
• Pathophysiology
• Biomechanics
• Treatment

3. INTRODUCTION

4. Introduction
• Congenital coxa vara is a developmental abnormality characterized by
a primary cartilaginous defect in the femoral neck with
• an abnormal decrease in the femoral neck-shaft angle,
• shortening of the femoral neck,
• relative overgrowth of the greater trochanter,
• and shortening of the affected lower limb
• Typically the deformity either is not present at birth or is sufficiently
subtle not to be recognized at that time
• Affected patients almost invariably present after walking age, and
sometimes as late as adolescence, with a limp (Trendelenburg or
short-leg gait) and, in unilateral cases, relatively mild limb length
inequality

5. Introduction
• This disorder has specific radiographic characteristics and a unique clinical
presentation and should be distinguished from acquired causes of coxa vara
deformity and coxa vara associated with congenital femoral deficiency
• In the literature, however, confusion and controversy exist regarding
terminology and classification of this disorder
• Coxa vara has been variously referred to as “congenital," “developmental,"
“cervical,” and “infantile"
• To add to the confusion, some authors, in discussing developmental or
congenital coxa vara, do not distinguish between the disorder described here
and congenital coxa vara with short femur; others include acquired causes of
coxa vara also

6. Natural history radiographically of a child with congenital coxa vara and congenital short femur
A: Radiographic appearance of a 9-month-old girl at presentation with unilateral coxa vara and
congenital short femur
B: The same patient at 2 years of age showing progression in femoral shortening and varus deformity
C: Patient at 5 years of age with increased shortening and coxa vara deformity.

7. Introduction
• Furthermore, some cases of coxa vara are associated with skeletal dysplasias,
especially cleidocranial dysostosis, metaphyseal dysostosis, and some types of
spondylometaphyseal dysplasia
• Some authors exclude, and others include, this skeletal dysplasia-associated
type of coxa vara in series describing developmental coxa vara
• We believe that the term developmental coxa vara should be used to describe
the clinical entity characterized by postnatal presentation of coxa vara without
other known cause, with typically mild limb shortening and characteristic
radiographic features; the deformity may or may not be associated with a
generalized skeletal dysplasia
• Acquired forms of coxa vara and those associated with significant femoral
deficiency should be considered separate entities

8. ACQUIRED COXA VARA CONGENITAL FEMORAL DEFICIENCY WITH COXA
VARA/ DEVELOPMENTAL COXA VARA
(1) SCFE (1) Isolated
(2) Sequela of AVN of femoral epiphysis (2) Associated with skeletal dysplasia
-LCPD -Cleidocranial dysostosis
-Traumatic coxa vara
----Femoral neck fracture
----Traumic hip dislocation
-Metaphyseal dysostosis
-Sequela of reduction of DDH -Other skeletal dysplasias
-Septic necrosis
-other causes of AVN of the immature femoral head
(3) Coxa vara associated with pathologic bone disorders
-Osteogenesis imperfecta
-Fibrous dysplasia
-Renal osteodystrophy
-Osteopetrosis
-Other bone softening conditions affecting the femoral neck

9. The radiographic appearance of acquired coxa
vara in an 8-year-old child who had fibrous
dysplasia and a shepherd-crook deformity of
the proximal femur.
The radiographic appearance of acquired coxa
vara in a 7-year-old girl who had an
intertrochanteric left hip fracture.

10. The radiographic appearance of coxa vara
associated with cleidocranial dysostosis in a 4-
year-old child.
Radiographic appearance of developmental
coxa vara in a 3-year-old child.

11. Introduction
• Fiorani in 1881 was the first to publish a clinical description of a case
of bending of the neck of the femur
• The term coxa vara was coined by Hofmeister in 1894
• The association of coxa vara with other malformations was noted by
Kredel in 1896
• Amstutz in 1970 described two patients with coxa vara who had
previously had negative findings on radiographs of the hips
• The term developmental coxa vara was first used by Hoffa in 1905
and later by Duncan

12. TOPICS
• Introduction
• Incidence
• Etiology
• Clinical features
• Radiographic findings
• Pathophysiology
• Biomechanics
• Treatment

13. INCIDENCE

14. Incidence
• Developmental coxa vara is rare; its incidence was estimated by
Johanning to be 1 in 25,000 live births in the Scandinavian population
• It has no racial predilection
• The disorder appears to be equally common in boys and girls
• Various series report the ratio of unilateral to bilateral cases to be
between 1 :2 and 3: 1
• Bilateral cases may be more likely to be associated with generalized
skeletal dysplasia, so the examiner should seek further evidence of
such dysplasia during the physical and radiographic examination of
patients with bilateral coxa vara

15. TOPICS
• Introduction
• Incidence
• Etiology
• Clinical features
• Radiographic findings
• Pathophysiology
• Biomechanics
• Treatment

16. ETIOLOGY

17. Etiology
• The disorder is frequently present in skeletal dysplasias with known
genetic causes, such as the following: cleidocranial dysostosis;
metaphyseal dysostosis, Jansen type; and spondylometaphyseal
dysplasia, especially Kozlowski type
• All these skeletal dysplasias are autosomal dominant disorders
• There is also a presumed genetic cause in "isolated” developmental
coxa vara (not associated with a generalized skeletal dysplasia)
• Reports have noted the condition in families and in both homozygous
and heterozygous twins

18. TOPICS
• Introduction
• Incidence
• Etiology
• Clinical features
• Radiographic findings
• Pathophysiology
• Biomechanics
• Treatment

19. CLINICAL FEATURES

20. Clinical Features
• The deformity does not manifest until after birth and usually not until
walking age
• Clinically, the child presents with a painless limp resulting from a
combination of true Trendelenburg gait and relatively minor limb
length inequality in unilateral cases
• Easy fatigability or aching pain around the gluteal muscles may be a
complaint
• In patients with bilateral involvement, the complaint is usually of a
waddling gait, similar to that seen in bilateral developmental
dysplasia of the hips, with or without fatigue or muscular pain

21. Clinical Features
• On physical examination, abduction and internal rotation of the
affected hip are limited
• With increasing coxa vara, the tip of the greater trochanter translates
proximally relative to the center of the femoral head, and the origin
and insertion of the hip abductors approach each other
• The Trendelenburg test result is positive
• In contradistinction to developmental dysplasia of the hip, the patient
has no telescoping of the hip or other signs of instability, such as the
Ortolani sign
• Shortening is present in unilateral cases but seldom exceeds 3 cm at
skeletal maturity, even in untreated patients

22. Clinical Features
• Evidence of generalized skeletal dysplasia should be sought, especially
if the family history is positive for similar deformity or short stature,
the affected patient is of short stature, or involvement is bilateral
• None of these features specifically implies the presence of an
identifiable skeletal dysplasia, however, because family history, short
stature, and bilateral involvement can all be present in patients with
presumed isolated developmental coxa vara

23. TOPICS
• Introduction
• Incidence
• Etiology
• Clinical features
• Radiographic findings
• Pathophysiology
• Biomechanics
• Treatment

24. RADIOGRAPHIC FINDINGS

25. Radiographic Findings
• Plain anteroposterior (AP)
radiographs demonstrate a
decreased neck-shaft angle of
the affected hip and a widened
radiolucent line corresponding
to the proximal femoral physis

26. Radiographic Findings
• Also seen is characteristically, but not
universally, a triangular piece of bone
in the medial femoral neck abutting
the physis and bounded by two
radiolucent bands traversing the neck
and forming an inverted V
• The superior, more horizontal
radiolucent line is the capital femoral
physis; the inferior, more vertical line
is an abnormal area of faulty
maturation of cartilage and irregular
ossification

27. Radiographic Findings
• Acetabular dysplasia is often
seen with coxa vara, and the
more severe the varus of the
femoral neck, the greater is the
slope of the acetabulum and
sourcil
• A case of spondylometaphyseal
dysplasia

28. Radiographic Findings
• lf generalized skeletal dysplasia is suspected on the basis of the family
history or short stature in the affected individual, a skeletal survey will
reveal features characteristic of those conditions
• These features include deficiencies of the clavicle and medial portions
of the pubic rami in cleidocranial dysostosis, as well as generalized
physeal widening and angular deformity in metaphyseal dysostosis
• The radiographic differential diagnosis should also include coxa vara
produced by avascular necrosis (from trauma or infection, or
associated with developmental dysplasia of the hip or Legg-Calvé-
Perthes disease), and pathologic bone-associated conditions such as
osteogenesis imperfecta, fibrous dysplasia, osteopetrosis, or renal
osteodystrophy

29. Radiographic Findings
• The amount of varus deformity of an affected hip may be quantified
on AP radiographs by measuring the neckshaft angle, the head-shaft
angle, or the Hilgenrerer- epiphyseal angle (H-E angle) as described
by Weinstein and colleagues
• Because the pathophysiology and rationale for operative treatment
imply sagging or slippage of the femoral epiphysis (and the
triangular neck fragment characteristic of this condition), some
authors have found that traditional measurement of the neck-shaft
angle does not adequately reflect the amount of deformity,
anticipated surgical correction, or prognosis for spontaneous
progression or postoperative recurrence in this disorder
• Measurement of the angle between the axis of the femoral shaft
and a line perpendicular to the base of the femoral epiphysis, the
head-shaft angle, more accurately reflects the severity of the
deformity and its likely progression or correction

31. Radiographic Findings
• Weinstein and co-workers identified the prognostic value of the H-E angle, the angle
between the Hilgenreiner line and a line drawn parallel to the physis of the proximal
femur
• On an AP radiograph of the pelvis with the hips in neutral position, this angle is usually
between 0 and 25 degrees (average of 16 degrees, in Weinstein and colleagues' series of
100 normal hips)
• Weinstein and associates, in a study of 22 patients with coxa vara, found that in hips with
an H-E angle greater than 60 degrees the deformity invariably progressed and merited
surgical correction; hips with H-E angles less than 45 degrees remained stable or
improved and thus could be treated expectantly, and those with angles between 45 and
59 degrees had an indeterminate prognosis and had to be monitored for progression by
serial radiographs

32. TOPICS
• Introduction
• Incidence
• Etiology
• Clinical features
• Radiographic findings
• Pathophysiology
• Biomechanics
• Treatment

33. PATHOPHYSIOLOGY

34. Pathophysiology
• The precise cause of developmental coxa
vara is unknown, but the condition
probably results from a primary defect in
enchondral ossification of the medial part
of the femoral neck
• Early in fetal development, the proximal
femoral physis extends across the upper
end of the femur as a crescentic line of
cartilage columns that soon differentiate
into cervical (medial) epiphyseal and
trochanteric (lateral) apophyseal portions

35. Pathophysiology
• The medial cervical portion matures early, thus elongating the
femoral neck, and the ossification center of the capital femoral
epiphysis appears within the first 3 to 6 months of postnatal life
• The lateral portion of the crescentic physis matures into the greater
trochanteric apophysis, and the trochanteric secondary center of
ossification begins to ossify at 4 years of age

36. Pathophysiology
• The neck-shaft angle and the length of the upper end of the femur
are determined by the relative amount of growth at these two sites
• According to Von Lanz and Wachsmuth,as the mean angle of the
femoral neck and shaft is 148 degrees at 1 year of age, and it
gradually decreases to 120 degrees in the adult (Fig.)
• In investigations of fetal femoral head specimens, large amounts of
fibrous tissue rather than cancellous bone were found in the medial
part of the metaphysis of the femoral neck

38. Pathophysiology
• Thus the mechanically weak femoral neck could be passively
deformed into a varus angulation under the stress of muscle forces
and body weight, and the capital physis could migrate inferiorly
through this weakened portion of the femoral neck
• Creation of support of this weakened portion of femoral neck is part
of the rationale for the Y valgus-displacement osteotomy described by
Pauwels

39. Pathophysiology
• Biopsy specimens of the capital
femoral physis in patients have
generally revealed disorganized
islands of cartilage cells in relatively
reduced numbers; the normal
alignment into columns typical of a
healthy physis is absent, and no
calcification is evident in the physis

40. TOPICS
• Introduction
• Incidence
• Etiology
• Clinical features
• Radiographic findings
• Pathophysiology
• Biomechanics
• Treatment

41. BIOMECHANICS

42. Biomechanics
• According to Pauwels, in the normal hip the compressive force (R) is
perpendicular to the center of the hip joint (Fig. A)
• As a result the physeal cartilage and hyaline cartilage of the
acetabulum are under compressive force (D), which is evenly
distributed throughout

44. Biomechanics
• Normally, the physis is perpendicular to the resultant compressive
force R (Fig. B)
• Stresses on the medial side of the femoral neck are compressive (D),
whereas those on the lateral side are tensile (Z)
• In Figure-A, S represents the shearing force

46. Biomechanics
• In coxa vara, with a progressive decrease in the femoral neck-shaft
angle, the physis changes its position from horizontal to vertical and
thereby becomes increasingly inclined relative to force R (Fig- C to E)
• The shearing force across the physis gradually increases
• The upper femoral epiphysis tends to tilt and become displaced
medially, and the tensile stresses increase
• Growth of the femoral neck is less on the medial side than on the
lateral side

48. Biomechanics
• The femoral neck-shaft angle affects the direction, position, and
magnitude of loading and stressing of the proximal end of the femur
(Fig.)
• In coxa vara the femoral neck-shaft angle is decreased; consequently
the tip of the greater trochanter is elevated, and the position and
direction of muscular force (M) are altered
• The point of intersection (X) of muscular force (M) with the line of
action of the partial body weight (K) is lowered
• The resultant compressive force R (which connects point X with the
center of the femoral head) diverges more than normal in coxa vara,
and the lever arm (h) of the abductor muscles is lengthened

49. K
K
X
X

50. Biomechanics
• The length of the femoral neck also affects the magnitude of its
mechanical stressing
• The length of the lever arm (h) of the muscular force (M) is
diminished by shortening of the femoral neck (Fig.)
• In response to efforts to preserve equilibrium, the muscle forces and
resultant compressive forces (R) increase
• Therefore shortening of the femoral neck increases bending stress

52. TOPICS
• Introduction
• Incidence
• Etiology
• Clinical features
• Radiographic findings
• Pathophysiology
• Biomechanics
• Treatment

53. TREATMENT

54. Treatment
• The goals of treatment are
• to stimulate ossification and healing of the defective femoral neck,
• restore the femoral head-shaft angle to normal,
• and restore normal mechanical muscle function to the hip
abductors
• When correction of this deformity is indicated, surgery is required
• Abduction splinting, traction, and exercise are likely ineffective
• The presence of symptoms and the extent of proximal femoral
deformity as quantified by the H-E angle are the primary
determinants of the need for surgical correction of the deformity

55. Treatment
• Valgus osteotomy of some form is recommended in hips with an H-E
angle of 60 degrees or greater, is not usually required in patients with
an angle less than 45 degrees, and may or may not be required in
patients with angles between 45 and 59 degrees
• The last group of patients must be observed for evidence of
progression of deformity with serial radiography
• In addition, patients with symptomatic limp, Trendelenburg gait, or
progressive deformity merit valgus osteotomy

56. Treatment
• Valgus osteotomy of the upper femur at the intertrochanteric or subtrochanteric level is the most
effective way to correct the varus deformity, to rotate the proximal femoral physis from a vertical
to horizontal position (relieving shear stress on it), and to enhance ossification of the defects
• The timing of surgery has been the subject of some debate
• In very young children, only limited fixation of the mostly cartilaginous proximal femur is possible,
thereby potentially accentuating the acknowledged propensity for recurrence of the deformity
with further growth that is known to occur in such patients
• Conversely the severity of acetabular dysplasia often associated with developmental coxa vara
probably increases with increasing age, and the capacity for acetabular remodeling diminishes
with increasing age
• Thus most authors recommend valgus osteotomy in patients with sufficient deformity to warrant
the procedure as soon as bony development is deemed adequate by the treating surgeon to allow
secure fixation of the surgeon’s preference

57. Treatment
• Fixation options include the following: Steinmann pins to the proximal
and distal fragments incorporated in plaster; transfixing of crossed
Steinmann pins; external fixation with monolateral half-pin hxators;
or hybrid circular external fixation with wires and half-pins, wire loops
(as described by Pauwels), bifid plates (as described in Muller,
Allgower, and Willenegger’s text), standard blade plates, and dynamic
hip compression plates
• The last two options provide the most secure forms of internal
fixation in a child with adequate bony development, and we prefer
these forms

58. Treatment
• The amount of valgus correction clearly plays an important role in the
likelihood of recurrence of deformity with growth, estimated to occur
in 30% to 70% of cases
• Borden and co-workers described a technique of valgus osteotomy in
which the trochanteric region and the proximal shaft of the femur are
exposed through a lateral longitudinal approach (Fig.)

59. a
b a
b
b
c
Growth plate
Defect in neck of femur
140 degrees angled blade
plate
Line of osteotomy

60. Treatment
• An alternative form of internal
fixation suggested by Wagner is
performed with a bifurcated
plate driven through the
intramedullary surface of the
proximal fragment and secured
to the distal fragment with
screws (Fig.)

62. Treatment
• A variation of this technique is to
perform the osteotomy slightly
more proximally after insertion
of an appropriate-size screw of a
dynamic compression hip screw
device, insert the lateral distal
edge of the proximal fragment
into the medullary canal of the
distal fragment, and secure the
distal fragment to the plate
portion of the device

63. Treatment
• A more complex osteotomy is the cuneiform Y-shaped
intertrochanteric osteotomy as described by Pauwels
• The objectives of the intertrochanteric Y-osteotomy are to place the
capital femoral physis perpendicular to the resultant compressive
force and to decrease the bending stress in the femoral neck, as
described previously
• The operation must be executed precisely to achieve the objectives as
determined from preoperative drawings based on radiographs

64. Treatment
• On a transparent paper placed
on the radiograph, the hip joint,
the physis, and the axis of the
shaft of the femur are drawn
• A horizontal line (H, parallel to
the Hilgenreiner line) is drawn to
transect the axis of the femoral
shaft 4 to 6 cm below the lesser
trochanter
Triangular neck fragment

65. Treatment
• Next a line (Ps, corresponding to the
epiphyseal line) is drawn through the physis
and extended inferiorly until it intersects the
horizontal line H
• From the point of intersection of the lines H
and Ps a third line is drawn inclined upward
16 degrees from the horizontal (this angle
corresponds to the average H-E angle in the
normal hip, and at this inclination, the forces
across the physis are presumably purely
compressive)
• The angle formed between the third line
(inclined upward) and the line Ps is the size of
the wedge to be resected (50 degrees in this
example; see Fig.)
16 degrees

66. Treatment
• Next the upper line of the intertrochanteric
osteotomy is drawn to extend from the base
of the greater trochanter to the lower portion
of the triangular neck fragment
• The point X is selected on this line so that the
length of the medial portion of the upper end
of the distal femoral fragment (A) equals the
length of the base of the femoral neck
fragment (B)
• Then the wedge to be resected is drawn from
a point X
Base of the GT
Lower portion of the triangular neck fragment
X
A
B

67. Treatment
• A new sheet of transparent paper is
superimposed on the first, and the
inferior fragment of the osteotomy with
its axis is traced (see Fig.)

68. Treatment
• The superimposed tracing sheet
is rotated with the distal
fragment until the osteotomy
lines of the two fragments
coincide, to simulate removal of
the wedge and closing of the
osteotomy site
• Then the upper fragment is
traced
• The two axes of the femoral
shaft should form an angle of 50
degrees (see Fig)
First sheet
Second sheet which is now rotated

69. Treatment
• The upper tracing sheet is rotated
back to the neutral position for the
hip and is slid upward parallel to the
femoral axis until the femoral head
lies in the acetabular socket of the
original sheet; then the acetabulum
is traced
• This represents the desired
radiographic appearance after the
osteotomy

71. Treatment
• This procedure is technically demanding, and we have limited
experience with it
• Pauwels described using a loop of wire as a tension band to connect
the lateral aspects of the proximal and distal fragments for internal
fixation, but fixation with a contoured plate or compression screw-
plate is probably more desirable

72. THANK YOU