The Thigh, Leg, and Knee
The Knee
Bones of the Knee include the femur, tibia, and patella. The Fibula, the lateral bone
of the lower leg is technically not a part of the knee joint.
Femur:
-
Thigh bone
Longest, strongest, heaviest bone in the body
The head of the femur is attached to the shaft by a region known
as the neck – susceptible to fractures
Has rounded condyles and epicondyles distally
Tibia:
-
Lateral and medial condyles proximally
Tibial tuberosity is the site of attachment of the patellar tendon
(Quadriceps)
Medial malleolus distally
Patella:
-
Kneecap
Largest sesamoid bone - a bone that is embedded within a tendon.
Sesamoid bones are found in areas where tendons pass over joints
-
lateral lower leg bone
Head of the fibula is proximal
Lateral malleolus is distal
Fibula:
The Femur, Tibia, and Patella form 2 separate joints at the knee:
1. Tibiofemoral joint
Formed by the femur superiorly and the tibia inferiorly.
It is a hinge joint that primarily permits flexion and
extension (but there is gliding and rolling of the tibia on
the femur)
2. Patellofemoral joint
Formed by the patella and the femur – gliding joint
Muscles of the Thigh
Can be divided into 3 basic regions:
Anterior thigh
- The quadriceps
- Vastus medialis, vastus lateralis, vastus intermedius, rectus
femoris
- Extend the leg at the knee joint
- Rectus femoris also cross the hip joint and acts as a hip flexor
Posterior thigh
Medial thigh
-
The hamstrings
Biceps femoris, semimembranosus, semitendinosus
Flex the leg at the knee joint
Adductors
Adductor longus, adductor magnus, adductor brevis, gracilis
Adduct the thigh and assist with flexion
The Sartorius is also a thigh muscle that originates on the hip, runs
diagonally down the thigh, and attaches to the medial tibial condyle.
Muscle and Actions
MUSCLE GROUP
Quadriceps
ACTION(S)
Rectus Femoris
Knee Extension, Hip flexion
Vastus Medialis
Vastus Lateralis
Knee Extension
Knee Extension
Vastus Intermedius
Knee Extension
MUSCLE GROUP
Hamstrings
ACTION(S)
Semitendinosus
Knee Flexion
Semimembranosus
Knee Flexion
Biceps Femoris
Knee FLexion
MUSCLE GROUP
Adductors
ACTION(S)
Adductor Longus
Thigh Adduction
Adductor Magnus
Thigh Adduction
Adductor Brevis
Thigh Adduction
Gracilis
Thigh Adduction
Sartorius
Tensor Fascia Latea
Knee flexion
Hip abduction, internal rotation, flexion
Hip flexion
Knee extension
The Knee Ligaments
The knee has many ligaments supporting the joint, however, there are 4 major
ligaments that serve to stabilize the joint.
1. The Cruciate Ligaments
Located inside the knee joint
a. Anterior Cruciate Ligament (ACL)
prevents forward displacement (movement) of the tibia and
prevents hyperextension
b. Posterior Cruciate Ligament
prevents posterior displacement of the tibia
it is the largest and strongest ligament in the knee
2. The Collateral Ligaments
a. Medial Collateral Ligament (MCL)
Primary structure that supports the medial aspect of the knee
Connects the femur to the tibia
Provides stability against a valgus stress
b. Lateral Collateral ligament (LCL)
Provides lateral stability to the knee
Connects the femur to the head of the fibula
Provides stability against a varus stress
The Knee Meniscus
A pair of half-mooned, wedged shaped cartilages (the lateral and medial meniscus)
found between the femur and the tibia.
Blood supply to the meniscus is limited to the outer 25% of the structure – it is
basically AVASCULAR.
Functions:
1. Shock absorbers
2. Increase the surface area for contact between the femur and the tibia
3. Increases stability of the knee joint
Conditions and Injuries to the Knee
Knock Knees
- Knees touch, but the ankles do not touch
- By puberty, the legs begin to straighten out
- aka Genu Valgum
-
Can Result From a Problem or Disease:
a. Tibial injury
b. Osteomyelitis (bone infection)
c. Overweight or obesity
d. Rickets – disease due to lack of vitamin D
-
Treatment
Usually not treated
Surgery if it is severe and past late childhood
If caused by a disease such as rickets or osteomyelitis, treat the disease
Bowleg
-
Knees stay wide apart with ankles and feet together
Normal in children under 18 months
Due to folded position in the uterus
When baby becomes weight bearing, they straighten out
-
May be caused by illness:
a. Blounts disease – disease in children in which the tibia fails to
develop normally
b. Bone dysplasia – abnormal bone growth
c. Fractures that heal incorrectly
d. Lead or fluoride poisoning
e. Rickets
-
No treatment unless severe
Genu Recurvatum
-
Excess extension at the tibiofemoral joint
Knee hyperextension
Causes
a. Knee laxity
b. Quadriceps weakness
c. Poor tibia or femur alignment
d. Hip extensor weakness
Patellofemoral Disorders
 Problems with patella – most common cause of knee pain
 Anatomy:
- Patella is a sesamoid bone formed in Quad tendon
- Patellofemoral joint – patella and femur
- Compression forces –
<body weight during walking
2.5 x body weight during stairs
The Q Angle - The Q angle of the knee is a measurement of the angle between
the quadriceps muscles and the patella tendon and provides useful information about the
alignment of the knee joint.
Patellar Tendinitis
 Jumper’s Knee”
 Inflammation and degeneration of the tendon that connects the kneecap
(Patella) to the shin bone (Tibia).




Chondromalacia
Damage to the cartilage under the kneecap
Causes: abnormal patellar tracking
Most Common Symptom: Knee pain when walking up and down stairs
Prevention: strengthen quads
Minimize squats, downhill running, biking with low
seat
Patellar Dislocation
 Involves the patella sliding out of its position on the knee.
 Caused by direct blow or abnormal twisting of the knee
 Usually lateral
Osgood Schlatter
1. Painful swelling over tibial tuberosity
(patellar tendon insertion)
2. Usually occurs between 9-13 years of age
3. Pain increases with activity
Iliotibial Band Friction Syndrome
 Occurs where IT Band rubs over femur at the knee joint
 Common in running (esp. downhill) or any activity with repetitive
flexion
 Hills or stairs increase pain
 Lots of IT Band stretching
Popliteal Cyst
 “Baker’s Cyst”
 Fluid accumulation in posterior knee (popliteal space)
 Patient usually complains of a mass behind the knee
Prepatellar Bursitis
 “Housemaid’s Knee”
 Tender swelling over the kneecap (prepatellar bursa)
Pes Anserine Bursitis
 Inflammation of a bursa in your knee. The pes anserine bursa is located
on the inner side of the knee just below the knee joint.
 Tendons of three muscles attach to the shin bone (tibia) over this bursa
 SGT: Sartorius, Semitendinosis, Gracilis
ACL Sprain
1. MOI: twisting of knee
forced hyperextension
lateral blow to knee
*foot must be firmly anchored to
playing surface
2. 50% of people describe a “pop” in knee
3. Knee fills with blood quickly
Hemarthrosis
4. Usually immediate loss of motion
5. Knee feels unstable
 Anterior Drawer Test:
examiner attempts to slide the tibia forward which may indicate a torn ACL
ligament
Surgery
 Arthroscopic
 Graft options
Patellar Tendon
Semitendinosus
Gracilis
Cadaver
Synthetic
PCL Sprain
1. MOI: excessive hyperextension
hyperflexion
tibia forced posteriorly
(blow to front of knee)
“dashboard knee”
Possibly 90% of all PCL injuries due to motor vehicle accidents?
2.
3.
4.
5.
6.
Mild hemarthrosis
Posterior knee pain
Walk with knee slightly flexed, avoid full extension
Posterior sag of tibia
Surgery?
MCL Sprain
 MOI: Blow to the outside of the
knee = Valgus Force
Possible overuse –
breaststroke in swimmers
 Commonly associated with meniscal injuries – attached to medial
meniscus
 No surgery
 Valgus Stress Test:
tests for injury to the MCL ligament
 Varus Stress Test:
tests for injury to the LCL ligament
Meniscal Injuries
1. MOI: Rotation of the knee as the
pivoting
knee extends during rapid cutting or
2. Signs and Symptoms:
- pain
- joint line tenderness
- catching or locking
- knee buckling or giving way
- swelling
- incomplete flexion
- clicking on stair climbing
3. Surgery?
Meniscectomy: removal of the meniscus
- Total meniscectomy = osteoarthritis
Depends on location of tear, type of tear, and blood supply