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Anatomy and classification neck femur in young adult
Dr.Rajesh Kumar RajnishDept. of Orthopaedics,
UCMS & GTB hospital, Delhi
Introduction
• Fractures of hip have been described as an orthopaedic epidemic
• Estimated global incidence-1.66 million fractures(1990).
• Expected to increase to 6.26 million fractures by 2050.
• Approx. 50% of these-intracapsular fractures.
Hip joint
• Ball-and-socket joint composed of head of femur and acetabulum
AnatomyProximal femur
The outline of the proximal end of the femur is characterised by almost spherical head, slightly flattened neck and two trochanters with communicating intertrochanteric ridge
• Physeal closure age 16yrs
• Neck-shaft angle 130°-135° <Coxa vera > Coxa valga
Anteversion (Medial femoral torsion)
• Angle subtended by femoral neck to the transcondylar axis of the knee joint.
15°- 25°
Calcar Femorale• Dense vertical palte of bone
from Posteromedial femoral shaft under LT to GT
• Reinforcing posterinferior femoral neck
Trabecular patterns
• Principal Compressive Group
• Principal Tensile Group • Greater Trochanteric
Group• Secondary Compressive
Group• Secondary Tensile Group• Ward's Triangle
Blood supply
Crock described three major groups of vessels
• Extracapsular arterial ring• Ascending cervical branches of arterial
ring • Artery of ligamentum teres
• Formed at base of femoral neck at level of capsular attachment
• Posteriorly – branch of medial circumflex femoral artery
• Anteriorly – ring is completed by branches of lateral circumflex femoral artery
• Minor contributions Superior and inferior gluteal arteries
Extracapsular ring
Medial circumflex femoral artery
It is a branch of• profunda femoral artery • femoral artery (rarely) • Participates in formation of extracapsular ring• Major contributor in extracapsular ring
Medial circumflex femoral artery
Gives of various branches – Medial ascending cervical arteries (inferior
retinacular, medial metaphyseal)– Posterior ascending cervical arteries– Arterial branches to superior gluteal artery– Branches to greater trochanter
Lateral ascending cervical artery– Terminal branch– Gives off metaphyseal branches to neck &
continues as lateral epiphyseal artery, a prominent vessel, for femoral head
– Provides most of blood supply to femoral head in children 3 to 10 years of age
Lateral circumflex femoral artery
It is a branch of• Profunda femoral artery • Femoral artery (rarely)• Participates in formation of extracapsular ring• Gives anterior ascending cervical arteries to
neck and femoral head
Ascending cervical arteries
• Also known as retinacular arteries (Within the capsule), described initially by Weitbrecht
• Derived from extracapsular arterial ring • Enters capsule at base of neck • Subsynovial course • Supplies metaphysis and epiphysis
• Ascend on surface of femoral neck in four groups:– Anterior– Posterior– Medial– Lateral
• Lateral group most important- largest contributor to femoral head. If damaged More chances of AVN
Subsynovial intra-articular arterial ring
• At the articular margin of femoral head
• Formed by vessels that penetrate the head (epiphyseal arteries)
• Lateral epiphyseal vessels supplying lateral weight-bearing portion most important
• Joined by vessels from ligamentum teres.
Artery of ligamentum teres
• Branch of Obturator artery or Medial circumflex femoral
artery• Gives blood supply to a small area of head of
the femur• Contribute little blood supply to femoral head
until age 8 and then only about 20% as an adult .
• Not sufficient to maintain blood supply of feoral head.
Blood supply of metaphysis
• Extracapsular arterial ring • Anastomoses with intramedullary branches of
the superior nutrient artery system• Branches of the ascending cervical arteries• Subsynovial intra-articular ring (descending
metaphyseal arteries)
Significance Blood supply of metaphysis
• Excellent vascular supply to metaphysis explains the absence of avascular changes in the femoral neck as opposed to the head.
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CLASSIFICATION
ANATOMICAL LOCATION • Subcapital• Transcervical• Basicervical (base of the neck fracture)
Classification
Pauwels Classification
• Based on the angle of the fracture line across the femoral neck.
• Relates to biomechanical stability• Predictive of more fixation failure and
nonunion with increasing angle • More vertical fracture has more shear force
Classification
• Pauwels – Angle describes vertical shear vector
Garden Classification
• Based on the degree of displacement of the fracture noted on pre-reduction antero-posterior x-rays in relation to trabecular line in femoral head to those in acetabulum
• Most frequently used• Four groups
Garden Classification
I Valgus impacted or incomplete
II Complete Non-displaced
III Complete Partial displacement
IV Complete Full displacement
Garden Classification
• Poor interobserver and intraobserver reliability.• Outcome of undispalced and displaced
fractures are independent of grade assinged.• Modified to:– Non-displaced
• Garden I (valgus impacted)• Garden II (non-displaced)
– Displaced• Garden III and IV
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Orthopaedic Trauma Association (OTA) Classification
• Alphanumeric fracture classification• Femoral neck fractures are designated type 31B• 31 is the proximal femur group and B the
femoral neck subgroup• Its complexity limits its usefulness in routine
clinical practice• Mainly used for research purposes• Neither useful in selecting treatment option nor
in predicting outcome.
• B1 group fracture is undisplaced to minimally displaced subcapital fracture
• B2 group includes transcervical fractures through the middle or base of the neck
• B3 group includes all displaced non-impacted subcapital fractures
3405/02/2023
Singh Index
• Based on the pattern of proximal femoral trabecular line
• A method of estimating degree of osteoporosis• Six separate categories
Grade VI:• All normal trabecular groups are visible• Upper end of femur seems to be completely occupied by
cancellous bone
Grade V:• Principal tensile & principal compressive trabeculae is
accentuated• Ward's triangle appears prominent
Grade IV:• Principal tensile trabeculae are markedly reduced but can still
be traced from lateral cortex to upper part of the femoral neck
• Grade III:
• A break in the continuity of the principal tensile trabeculae opposite the greater trochanter
• this grade indicates definite osteoporosis
Grade II:• Only principal compressive trabeculae stand out
prominently
Grade I:• principal compressive trabeculae are markedly reduced
in number and are no longer prominent
Limitations
• Little practical value.• Poor interobserver and intraobserver leves of
agreement• Does not correlate with bone density as
measured.
05/02/2023 40
Imaging and other Diagnostic Studies
Radiography •Preferred initial modality in evaluating femoral neck fractures•AP and Lateral views•Lateral view gives idea regarding dispalcement
05/02/2023 41
Limitations
• Spiral fractures are difficult to assess on a
single view.• Comminution is not easily demonstrated• Some stress fractures are simply not visible on
plain images.
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COMPUTED TOMOGRAPHY• Because of its superior resolution, cross-sectional
capabilities, and amenability to image reconstruction in the coronal and saggittal planes,
• Useful for assessing fracture comminution preoperatively and in determining the extent of union (or lack there of) postoperatively.
05/02/2023 43
MRI
• In cases of doubtful diagnosis MRI may be useful additional modality.
• Can also show soft tissue problems associated with hip pain in absence of fracture.
Limitations • Relative lack of widespread availability• Its higher costs• Exclusion of patients with cardiac pacemakers
05/02/2023 44
Nuclear Medicine
• In past technititium bone scan was used in situations when plane radiography not able to show fracture.
• Usually show positive result in fracture neck femur.
• False negative results in osteopenic bone if carried out within 48-72 hrs of injury.
• Sensitive but not specific • CT scan is more accurate