Session 4a - Bones And Joints Of The Proximal Lower Limb

Question 1

What terms are used to describe different regions of the lower limb?

Answer 1

● The pelvis – the two hip (innominate) bones and the sacrum.
● The thigh – between the hip and knee joints. The bone of the thigh is the femur. The thigh contains anterior, medial, and posterior muscle compartments.
● The leg – between the knee and ankle joint. The bones of the leg are the tibia and fibula. It contains anterior, lateral, and posterior muscle compartments.
● The foot – distal to the ankle. The plantar surface (sole) contains many small muscles (like the palm of the hand). The ‘top’ of the foot is the dorsum.

Question 2

What joints are in the lower limb?

Answer 2

● Hip joint – allows flexion, extension, abduction, adduction, and internal and external rotation of the lower limb. It is a synovial ball and socket joint formed by the articulation between the acetabulum and the proximal femur. It is very stable but also quite mobile (but not as mobile as the shoulder).
● Knee joint – allows flexion and extension of the leg. It is a synovial hinge joint formed by the articulation of the distal femur with the tibia.
● Ankle joint – allows plantarflexion and dorsiflexion of the foot. It is a synovial hinge joint formed by the articulation between the distal ends of the tibia and fibula with the talus.

Question 3

What are the movements of the lower limb joints and toes?

Answer 3

● Hip joint – flexion, extension, abduction, adduction, internal (medial) rotation, external (lateral) rotation, and circumduction.
● Knee joint – flexion and extension.
● Ankle joint – dorsiflexion and plantarflexion.
● Toes – flexion and extension, adduction, and abduction.

Question 4

What is the pelvis?

Answer 4

The pelvis is a bony ring formed by the articulation of the left and right innominate (hip) bones and the sacrum. The pelvis takes the weight of the body and transmits it to the lower limbs.

Question 5

What is each hip bone formed from?

Answer 5

Each hip bone is formed from three separate bones – the pubic bone, the ilium and ischium, which fuse at the acetabulum – the socket of the hip joint. The hip bones articulate anteriorly with each other at the pubic symphysis and posteriorly with the sacrum at the sacroiliac joints.

Question 6

What surrounds the obturator foramen?

Answer 6

The superior and inferior pubic rami (singular: ramus) surround the obturator foramen. In life, the obturator foramen is almost completely closed over by the obturator membrane and muscles attached to it. A small gap in the membrane and the muscles – the obturator canal – allows vessels and nerves to pass between the pelvis and thigh.

Question 7

What is the uppermost part of the ilium?

Answer 7

The uppermost part of the ilium is the iliac crest. These are palpable through the skin. Anteriorly, the anterior superior iliac spine (ASIS) and anterior inferior iliac spine (AIIS) are prominent.

Question 8

What are the two bony prominences which project from the ischium?

Answer 8

Posteriorly and inferiorly, there are two key bony prominences which project from the ischium:
● The sharp ischial spine. The sacrospinous ligament attaches to it.
● The bulky ischial tuberosity. The sacrotuberous ligament attaches to it along with muscles of the posterior thigh. This part is often palpable through the skin, and we sit on this part of the pelvis.

Question 9

What is above and below the ischial spines?

Answer 9

Above and below the ischial spines, are two notches known as the greater and lesser sciatic notches. The sacrotuberous and sacrospinous ligaments close these notches to form the greater and lesser sciatic foramina. These ligaments connect the sacrum to their respective bony prominence, the ischial tuberosity or ischial spine. The foramina allow structures to pass between the pelvis and the gluteal region and perineum.

Question 10

What is the femur?

Answer 10

The femur is the long bone of the thigh. Like the humerus, it has a head, neck and shaft, and its distal end is expanded to from two condyles.

Question 11

What is the structure of the femur?

Answer 11

● The head of the femur articulates with the acetabulum of the pelvis to form the hip joint.
● The neck of the femur extends laterally and distally from the head.
● The greater and lesser trochanters are located distal to the neck. They are sites of muscle attachment similar to the tubercles of the humerus.
● The intertrochanteric line is located between the greater and lesser trochanters on the anterior surface of the femur.
● The linea aspera is a bony vertical ridge on the posterior aspect of the shaft of the femur. It is a site of muscle attachment.
● The gluteal tuberosity is located just inferior to the trochanters on the posterior aspect of the femur. It is a site of muscle attachment.
● The distal end of the femur is expanded to form the medial and lateral femoral condyles. These articulate with the proximal tibia at the knee joint.
● Just superior to the medial femoral condyle is the small adductor tubercle.
● The patella is located anterior to the knee joint.

Question 12

What is the hip joint like?

Answer 12

The hip is a synovial ball and socket joint formed by the articulation between the acetabulum of the hip (innominate) bone and the femoral head. The weight of the body is transmitted through the lumbar vertebrae and the sacroiliac joints to the hip joints. The hip is a stable joint as the acetabulum is deep and there is a good fit between it and the femoral head. A rim of fibrocartilage - the acetabular labrum – deepens the acetabulum for even more stability.

Question 13

Why is the ligament of the head of the femur like?

Answer 13

The ligament of the head of the femur is a weak ligament that attaches the femoral head to the centre of the acetabulum. The joint capsule is reinforced by other strong ligaments.

Question 14

What is the blood supply of the hip joint like?

Answer 14

The arteries to the hip joint (medial and lateral circumflex femoral arteries) arise mainly from the profunda femoris. They give rise to retinacular arteries that run along the neck of the femur to supply the femoral head. They can be torn by fractures of the femoral neck.

Question 15

What are the movements of the hip joint?

Answer 15

The movements possible at the hip joint are flexion, extension, abduction, adduction, internal (medial) and external (lateral) rotation and circumduction.
● Muscles in the anterior thigh flex the thigh at the hip joint.
● Muscles in the medial thigh adduct the thigh at the hip joint.
● Muscles in the posterior thigh extend the thigh at the hip joint.
● Muscles of the gluteal region extend, abduct and rotate the thigh at the hip joint.

Question 16

What ligaments is the hip joint stabilised?

Answer 16

The hip joint is stabilised by three ligaments - the iliofemoral, pubofemoral and ischiofemoral ligaments. The iliofemoral and pubofemoral are anterior ligaments, whilst the ischiofemoral is posterior to the joint. As the hip is extended, these ligaments become taut and hold the femur more tightly.

Question 17

What is the knee joint like?

Answer 17

The knee is a synovial hinge joint formed by the articulation between the femoral condyles and the tibial condyles. The most superior aspect of the tibial condyles forms a pair of flat surfaces known as the tibial plateaus. As the tibial plateaus are flat, they do not provide a good fit for the femoral condyles.

Question 18

How are the femur and tibia attached?

Answer 18

The femur and tibia achieve their ‘best fit’ with each other when the knee is extended, hence the knee is most stable in extension. To help us to stand for long periods, the femur rotates a very small amount as the knee reaches full extension. The means the knee ‘locks’ in place and becomes very stable. A small muscle called popliteus is responsible for ‘unlocking’ the knee by rotating the femur back again to permit flexion.

Question 19

What contributes to the stability of the knee joint?

Answer 19

The muscles, tendons, cartilage, and ligaments that surround the knee joint also contribute to its stability, as does the iliotibial tract which attaches to the lateral aspect of the tibia.

Question 20

What movements are possible at the knee joint?

Answer 20

The movements possible at the knee joint are flexion and extension. Muscles in the anterior thigh extend the leg at the knee joint. Muscles in the posterior thigh flex the leg at the knee joint.

Question 21

What are menisci?

Answer 21

The menisci (singular = meniscus) are C-shaped cartilages that sit on the tibial plateaus. They are wedge-shaped, with the thickest part at the periphery and the thinnest part in the centre. They act to deepen the tibial condyles for articulation with the femoral condyles, thus improving the fit between them.

Question 22

What is the medial meniscus attached to?

Answer 22

The medial meniscus is attached to the joint capsule along its peripheral margin and is attached to the medial (tibial) collateral ligament. These attachments make it prone to injury if the knee is twisted. The lateral meniscus is not attached to the lateral (fibular) collateral ligament; it can move more freely, so is less prone to injury.

Question 23

What are the important ligaments of the knee?

Answer 23

The most important ligaments of the knee are the collateral and the cruciate ligaments.

Question 24

What are the ligaments of the knee?

Answer 24

The medial (tibial) and lateral (fibular) collateral ligaments support the knee and resist sideways movement of the tibia on the femur. The medial collateral ligament (MCL) connects the femur to the tibia and the lateral collateral ligaments (LCL) connects the femur to the fibula.

Question 25

What is the medial collateral ligament attached to?

Answer 25

The medial collateral ligament is attached to the medial meniscus, but the lateral collateral ligament is not attached to the lateral meniscus – this arrangement has clinical implications.

Question 26

What do the anterior and posterior cruciate ligaments do?

Answer 26

The anterior and posterior cruciate ligaments connect the tibia to the femur and are named according to their attachments to the tibia. ‘Cruciate’ is derived from the Latin for ‘cross’.

Question 27

What is the ACL attached to?

Answer 27

The anterior cruciate ligament is attached to the anterior part of the intercondylar area of the tibia. It attaches to the medial aspect of the lateral condyle of the femur. It prevents the tibia moving anteriorly relative to the femur (or, to think of it another way, it prevents the femur moving posteriorly relative to the tibia). Being able to pull the tibia anteriorly indicates ACL injury. The ACL is taut in knee extension, and lax when the knee is flexed.

Question 28

What is the PCL attached to?

Answer 28

The posterior cruciate ligament is attached to the posterior part of the intercondylar area of the tibia. It attaches to the lateral aspect of the medial condyle of the femur. It prevents the tibia moving posteriorly relative to the femur (or, to think of it another way, it prevents the femur moving anteriorly relative to the tibia). This ligament is therefore crucial for stability of the knee when walking downhill or downstairs. Being able to push the tibia posteriorly indicates PCL injury. The PCL is most taut in knee flexion.

Question 29

What is a neck of femur fracture (NOF)?

Answer 29

Neck of Femur (NOF) fracture
A ‘fractured hip’ refers to a fracture of the femoral neck. This is very common in the elderly population and can be caused even by a low energy fall. Osteoporosis is often a contributing factor. Patients typically have pain in the groin and are unable to bear any weight on the affected leg. The typical finding on examination is shortening and external rotation of the affected limb compared to the uninjured limb. The fracture may tear the vessels that supply the femoral head and neck, leading to avascular necrosis of the femoral head.

Question 30

What is a patellar dislocation?

Answer 30

Dislocation of the patella is common. Dislocation is almost always lateral because the femur is angled obliquely relative to the tibia and so the angle of the pull of quadriceps is also oblique. The distal fibres of vastus medialis are arranged horizontally and these usually resist lateral movement of the patella. Additionally, the patellofemoral joint has a larger ridge laterally in an attempt to resist to lateral dislocation. Dislocated patellae are relatively easy to relocate and often simply require extension of the leg at the knee, and a small push on the patella.

Question 31

What is the osteoarthritis of the hip and knee joints?

Answer 31

Osteoarthritis of the hip joint and knee joint is very common. It causes progressive pain and limited mobility. Hip and knee replacements are two of the most common surgical procedures undertaken in the UK.

Question 32

What is the posterior dislocation of the hip?

Answer 32

Dislocation of the hip requires significant force because the joint is very stable. Posterior dislocation of the femoral head tends to occur in car accidents when the knee forcibly impacts the dashboard. The force is transmitted along the femur and the head is forced posteriorly. The acetabulum may fracture. A posterior dislocation risks injury to the sciatic nerve, which is located just behind the hip joint.

Question 33

What are the meniscal and ligament injuries at the knee?

Answer 33

Meniscal and ligament injuries at the knee
The menisci can be torn by twisting injuries of the knee. Tears of the medial (tibial) collateral ligament result from a lateral blow to the knee or twisting injuries. Because it is attached to the medial meniscus, the meniscus may also tear. Anterior cruciate injury is typically also caused when there is a lateral blow to a partially flexed knee. In some cases, all three of these structures can be damaged in a single injury, and this is known as the ‘unhappy triad of the knee’. It is most often seen as a sporting injury, particularly amongst those who play football or rugby. Ligament injuries cause instability of the joint