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The Joints of the Lower Limb

The Hip Joint

The hip joint is a synovial ball-and-socket joint, the femoral head functioning as a ball with the acetabular cavity or socket

The normal acetabulum is obliquely oriented, is inclined such that the outer margin of the roof is lateral to the outer margin of the floor

Articular Surfaces

1.The transverse ligament passes between anterior horns of menisci.7

LEC 9 RADIOLOGICAL ANATOMY 2 ND YEAR

Plain radiographs of the knee joint

The ligamentum patellae is made visible as its outlined subcutaneous and intraarticular fat (the infrapatellar fat pad) The suprapatellar bursa is best seen on radiographs when distended with fluid.3 4

LEC 9 RADIOLOGICAL ANATOMY 2 ND YEAR

The Knee Joint

The knee joint is a hinge type synovial joint, which mainly allows for flexion and extension (and a small degree of medial and lateral rotation).S line Shenton's line along the inferior margin of the femoral neck & along the inferior margin of superior pubic ramus should form a continuous arc;

In assessment of radiographs of the adult hip, routine frontal radiographs allow the identification of six lines

1.The acetabulum has a central non-articular area for a fat pad and the ligamentum teres & an inferior notch bridged by the transverse acetabular ligament.Anterior cruciate ligament arises from anterior part of intercondylar area of tibia and inserted into inner aspect of lateral femoral condyle.Posterior cruciate ligament arises from posterior part of intercondylar area of tibia and inserted into inner aspect of medial femoral condyle

3.At the femoral neck it is attached to the trochanters and the intertrochanteric line anteriorly; posteriorly it is attached more proximally on the neck at the junction of its medial two-thirds and its lateral third.H line (Hilgenreiner line), horizontal line between the unossified center of each acetabulum, that is, the Y-shaped cartilage between the pubis, ischium and ilium or the triradiate cartilage;

2.The continuation of the inferior margin of the superior pubic ramus superiorly to the upper outer margin of the acetabular roof forms the anterior wall of the acetabulum (line 1).The continuation of the inferior margin of the inferior pubic ramus superiorly to the upper outer margin of the acetabular roof forms the posterior wall of the acetabulum (line 2).Occasionally the joint cavity is also continuous with the bursa under the lateral head of the gastrocnemius muscle

Synovium lines the capsule and its associated bursae.2 3

LEC 9 RADIOLOGICAL ANATOMY 2 ND YEAR

Plain radiographs

In assessment of radiographs of the hip in infants, the following lines and angles are as described:

1.Articular Surfaces

1.Ligaments

1.4.5.2.3.4.5.6.2.4.5.

The Joints of the Lower Limb

The Hip Joint

The hip joint is a synovial ball-and-socket joint, the femoral head functioning as a ball with the acetabular cavity or socket

The normal acetabulum is obliquely oriented, is inclined such that the outer margin of the roof is lateral to the outer margin of the floor

Articular Surfaces

1. 
   

   The head of the femur (apart from the fovea),

   
   


2. 
   

   A horseshoe-shaped articular surface on the acetabulum. The acetabulum has a central non-articular area for a fat pad and the ligamentum teres & an inferior notch bridged by the transverse acetabular ligament. The articular surface is deepened by a fibrocartilaginous ring, the acetabular labrum.

   
   

Capsule: This is attached to

1. 
   

   The edge of the acetabulum and its labrum

   
   


2. 
   

   At the femoral neck it is attached to the trochanters and the intertrochanteric line anteriorly; posteriorly it is attached more proximally on the neck at the junction of its medial two-thirds and its lateral third.

   
   

1 2

LEC 9 RADIOLOGICAL ANATOMY 2 ND YEAR

Synovium

1. 
   

   lines the capsule

   
   


2. 
   

   Occasionally bulges out anteriorly as a bursa between the psoas muscle & the hip joint.

   
   

Ligaments These are as follows:

1. 
   

   The iliofemoral ligament between the anteroinferior iliac spine and the intertrochanteric line

   
   


2. 
   

   The ischiofemoral ligament is a posterior

   
   


3. 
   

   The pubofemoral ligament inferiorly.

   
   


4. 
   

   The transverse acetabular ligament bridges the acetabular notch.

   
   


5. 
   

   The ligamentum teres lies between the central non- articular part of the acetabulum and the fovea of the head of the femur.

   
   

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LEC 9 RADIOLOGICAL ANATOMY 2 ND YEAR

Plain radiographs

In assessment of radiographs of the hip in infants, the following lines and angles are as described:

1. 
   

   H line (Hilgenreiner line), horizontal line between the unossified center of each acetabulum, that is, the Y-shaped cartilage between the pubis, ischium and ilium or the triradiate cartilage;

   
   


2. 
   

   P line (Perkin line) vertical line from outer margin of the acetabulum

   
   


3. 
   

   The acetabular angle, normally 15-35°;

   
   


4. 
   

   S line Shenton's line along the inferior margin of the femoral neck & along the inferior margin of superior pubic ramus should form a continuous arc;

   
   

In assessment of radiographs of the adult hip, routine frontal radiographs allow the identification of six lines

1. 
   

   The continuation of the inferior margin of the superior pubic ramus superiorly to the upper outer margin of the acetabular roof forms the anterior wall of the acetabulum (line 1).

   
   


2. 
   

   The continuation of the inferior margin of the inferior pubic ramus superiorly to the upper outer margin of the acetabular roof forms the posterior wall of the acetabulum (line 2).

   
   


3. 
   

   The continuation of the superior margin of the superior pubic ramus superiorly forms the iliopectineal line (line 3).

   
   


4. 
   

   The continuation of the superior margin of the inferior pubic ramus superiorly forms the ilioischial line (line 4).

   
   


5. 
   

   The roof of the acetabulum forms line 5.

   
   


6. 
   

   The 'tear drop' is line 6.

   
   

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LEC 9 RADIOLOGICAL ANATOMY 2 ND YEAR

The Knee Joint

The knee joint is a hinge type synovial joint, which mainly allows for flexion and extension (and a small degree of medial and lateral rotation). It is formed by articulations between the patella, femur and tibia.

Articular Surfaces

1. 
   

   The condyles of the femur

   
   


2. 
   

   The articular surfaces on the tibial plateau,

   
   


3. 
   

   The patellar surfaces of the femur & the deep surface of the patella.

   
   

4 5

LEC 9 RADIOLOGICAL ANATOMY 2 ND YEAR

Capsule

1. 
   

   Attached at the margins of the articular surface

   
   


2. 
   

   Extends superiorly as the suprapatellar bursa (between quadriceps femoris muscle and the femur)

   
   


3. 
   

   Posteriorly where it communicates with the bursa under the medial head of gastrocnemius

   
   


4. 
   

   Occasionally the joint cavity is also continuous with the bursa under the lateral head of the gastrocnemius muscle

   
   

Synovium lines the capsule and its associated bursae.

A fat pad in the joint deep to the ligamentum patellae is called the infrapatellar fat pad.

Ligaments

1. 
   

   The medial collateral ligament (between the medial condyle of the femur & the medial condyle of the tibia)

   
   


2. 
   

   The lateral collateral ligament (between the lateral femoral condyle & the fibula)

   
   


3. 
   

   The ligamentum patellae (between the lower border of the patella & the tibial tuberosity)

   
   


4. 
   

   The oblique popliteal ligament posteriorly.

   
   

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LEC 9 RADIOLOGICAL ANATOMY 2 ND YEAR

Internal structures

1. 
   

   Anterior cruciate ligament arises from anterior part of intercondylar area of tibia and inserted into inner aspect of lateral femoral condyle.

   
   


2. 
   

   Posterior cruciate ligament arises from posterior part of intercondylar area of tibia and inserted into inner aspect of medial femoral condyle

   
   


3. 
   

   The medial and lateral menisci are two fibrocartilaginous structures, which slightly deepen the articular surface of the tibia. The medial meniscus is bigger, less curved. The lateral meniscus is smaller, more curved (nearly circular rather than semicircular) Each is attached peripherally to the tibia and to the capsule. Each has an anterior and posterior horn attached to the intercondylar area of the tibia.

   
   


4. 
   

   The transverse ligament passes between anterior horns of menisci.

   
   


5. 
   

   The meniscofemoral ligament passes between the posterior horn of the lateral meniscus and the medial femoral condyle.

   
   

7

LEC 9 RADIOLOGICAL ANATOMY 2 ND YEAR

Plain radiographs of the knee joint

The ligamentum patellae is made visible as its outlined subcutaneous and intraarticular fat (the infrapatellar fat pad) The suprapatellar bursa is best seen on radiographs when distended with fluid. It is then seen as a soft-tissue density above the patella.