Download The Knee and Related Structures

The Knee and Related Structures
Overview
The knee is one of the most complex joints in the human body. It is also one of the most traumatized joints
because many sports place extreme stress on it. The team physician is responsible for diagnosing the severity and exact
nature of a knee injury. Although the physician makes the final evaluation, the coach or athletic trainer is usually the first
person to observe the injury; therefore he or she makes the initial evaluation and provides immediate care. The earlier the
determination of the extent of the injury, the better, because subsequent swelling will often mask the full extent of the
injury.
Any evaluation of the knee should include inspection and evaluation of the patella. Because of its position,
function, and its relationship to surrounding structures, it is exposed to a variety of traumas and diseases related to sports
activities that may cause pain and discomfort for the athlete. All structures must be thoroughly evaluated in both acute
and chronic conditions to rule out more serious pathological conditions.
As with any injury, the athletic trainer's job does not stop after the evaluation and immediate treatment. In
cooperation with the team physician, a rehabilitation program should be constructed to restore the athlete's muscle
strength, power, endurance, flexibility, proprioception, and agility before allowing the athlete to return to sports
activities.
I.
Anatomy of the Knee
A. Bones
1. Knee joint consists of the femur, tibia, fibula and patella
2. Patella is largest sesamoid bone in the human body
3. Patella located in the tendon of quadriceps femoris, is divided into three medial
facets and a lateral facet that articulate with the femur
4. Patellar tracking depends upon the pull of the quadripceps muscle and patellar
tendon, the depth of the trochlear groove and the shape of the patella
B. Articulations
1. Joints exist between the femur and tibia, femur and patella, femur and fibula
and the tibia and fibula
C. Menisci
1. Medial Meniscus
a. C-shaped fibrocartilage, circumference attached firmly to the medial
articular facet of the tibia and to the joint capsule by coronary ligaments
b. Attached posteriorly to semimembranosus muscle
c. Helps to stabilize the knee, when the knee is flexed at 90 degrees
2. Lateral Meniscus
a. O-shaped attached to the lateral articular facet on the superior aspect of the
tibia
b. Also attached loosely to the lateral articular capsule and the popliteal
tendon
3. Meniscal Blood Supply
a. Divided into the red-red zone (good blood supply on outer one-third), redwhite zone (middle one-third minimal blood supply), and the white-white
zone (inner one-third is avascular)
D. Stabilizing Ligaments
1. Anterior Cruciate Ligament
a. Prevents the femur from moving posteriorly during weight bearing
b. Stabilizes the tibia against excessive internal rotation, stabilizes knee in full
extension and prevents hyperextension
c. Secondary restraint for valgus or varus stress
d. Knee fully extended, posterolateral secton is tight, in flexion the
posterolateral fibers loosen and anteromedial fibers tighten
2. Posterior Cruciate Ligament
E.
F.
G.
H.
I.
a. Some portion of PCL is taut throughout the full range of motion
b. Prevents hyperextension of the knee and femur
c. Resists internal rotation of the tibia
3. Medial Collateral Ligament
a. Attaches above the joint line on the medial epicondyle of the femur and
below on the tibia, just beneath attachment of pes anserine
b. Prevents the knee from valgus and external rotatory forces
4. Lateral Collateral Ligament and Related Structures
a. Taut during knee extension but relaxed during flexion
b. Attached to the lateral epicondyle of the femur and to the head of the fibula
c. Popliteus muscle stabilizes the knee during flexion and protects the lateral
meniscus pulling it posteriorly
Joint Capsule
1. Articular surfaces of the knee joint enveloped by the largest joint capsule in the
body
2. Divided into four regions: Posterolateral, posteromedial, anterolateral and
anteromedial
3. Posterolateral corner reinforced by the IT band, the popliteus, the biceps
femoris, the LCL and the arcuate ligament
4. Posteromedial corner reinforced by MCL, pes anserine tendons,
semimembranosus and posterior oblique ligament
5. Anterolateral corner reinforced by IT Band, patellar tendon, and lateral patellar
retinaculum
6. Anteromedial corner reinforced by superficial MCL, and medial patellar
retinaculum
Knee Musculature
1. Knee flexion: biceps femoris, semitendinosus, semimembranosus, gracilis,
sartorius, gastrocnemius, popliteus and plantaris
2. Knee Extension: Vastus medialis, vastus lateralis, vastus intermedius, rectus
femoris
3. External Rotation of tibia: Biceps femoris
4. Internal Rotation: Popliteus, semitendinosus, semimembranosus, sartorius and
gracilis
5. IT Band functions as a dynamic lateral stabilizer
Bursae
1. Flattened sac composed of synovial tissue which is separated by a thin film of
fluid
2. Function is to reduce friction between anatomical structures
3. Most common around the knee joint: suprapatellar, prepatellar, infrapatellar,
pretibial and gastrocnemius bursae
Fat Pads
1. Infrapatellar fat pad is the largest
2. Cushions the front of the knee and separates the patellar tendon from the joint
capsule
Nerve and Blood Supply
1. Tibial nerve innervates most of the hamstrings and gastronemius
2. Common peroneal nerve innervates the short head of the biceps femoris
3. Peroneal nerve exposed at the head of the fibula
4. Femoral nerve innervates the quadriceps and sartorius
II.
III.
5. Main blood supply to the knee is from the popliteal artery: five branches –
medial and lateral superior genicular, middle genicular, and medial and lateral
inferior genicular arteries
Functional Anatomy
A. Movement between tibia and femur involves physiological motions of flexion,
extension and rotation and arthrokinematic motions of rolling, and gliding
B. As tibia extends on the femur – tibia glides and rolls anteriorly
Assessing the Knee Joint
A. History (current and recurrent or chronic injury)
B. Observation
1. Walking
2. Leg Alignment (genu varum, genu valgum, patellar position, genu recurvatum)
3. Patellar Malalignment
a. Patella Alta (patella sits higher than normal) – length of patellar tendon is
20% greater than the height of the patella
b. Patella Baja (patella sits lower than normal) – ratio of patellar tendon
length to the height of the patella is less than the normal 1:1 ratio
4. Patellar Orientation
a. Position of the patella in relation to the tibia
5. Leg-Length Discrepancy
C. Palpation
1. Bony
2. Soft-tissue
3. Swelling Patterns
a. Intracapsular – Inside the joint capsule (joint effusion)
b. Hemarthrosis: Swelling caused by synovial fluid and blood in the joint
c. Extracapsular – Outside the joint capsule (bursitis, tendonitis, or injury to
one of the collateral ligaments – will localize to the area)
d. Tests for Effusion (sweep maneuver and ballotable patella)
D. Special Tests for Assessment of Knee Joint Instability
1. Collateral Ligament Tests
a. Valgus and Varus Stress Tests at 0 and 30 degrees
b. Apley Distraction Test
2. Anterior Cruciate Ligament Tests
a. Drawer Test at 90 degrees of Flexion
b. Lachman Drawer Test
3. Posterior Cruciate Ligament Tests
a. Posterior Drawer Test
b. Posterior Sag Test (Godfrey’s 90/90 Test)
4. Meniscal Tests
a. McMurray’s Meniscal Test
b. Apley Compression Test
E. Girth Measurements
1. Five sites have been recommended: the joint line (tibial plateau), 8-10 cm
above the joint line, the level of the tibial tubercle, the belly of the
gastrocnemius muscle (measured in cm from the tibial tubercle, and 2 cm
above the superior border of the patella
F. Functional Examination
1. Observe athlete walking, running, turning, performing figure-eights, backing
up, and stopping.
2. Deep knee bends and duck walks – may help to rule out meniscal pathology
IV.
V.
3. Resistive strength of the hamstrings and quadriceps
G. Patellar Examinations
1. Measure the Q Angle: (normal is 10 degrees for males and 15 degrees for
females)
2. Palpation of the Patella
3. Patellar Compression, Patellar Grinding and Apprehension Tests
Prevention of Knee Injuries
A. Physical Conditioning and Rehabilitation
1. Muscles surrounding the knee joint must be strong and flexible (strength ratios:
hamstrings should have 60-70% of the strength of the quadriceps
B. ACL Injury Prevention Programs
1. Consists of instructional training techniques
2. Proprioceptive balance activities in preseason, have been shown to reduce
incidence of ACL injuries
3. Program involving combination of weight training, landing instructional cues,
stretching and plyometric training may potentially reduce the incidence of ACL
injuries
C. Functional and Prophylactic Knee Braces
1. The effectiveness of protective knee braces is controversial
2. Generally accepted that they have little or no effect on functional performance
measures
Recognition and Management of Specific Injuries
A. Ligament Injuries
1. Medial Collateral Ligament Sprain (Grade I, Grade II and Grade III)
2. Lateral Collateral Ligament Sprain
3. Anterior Cruciate Ligament Sprain
4. Posterior Cruciate Ligament Sprain
B. Meniscal Lesions
C. Joint Injuries
1. Knee Plica
2. Osteochondral Knee Fractures
3. Osteochondritis Dissecans
4. Joint Contusions
5. Peroneal Nerve Contusion
6. Bursitis
D. Patellar Conditions
1. Patellar fracture
2. Acute Patellar Subluxation/Dislocation
3. Injury to Infrapatellar Fat PadPatellofemoral
4. Chondromalacia Patella
E. Extensor Mechanism Injuries
1. Osgood-Schlatter Disease and Larsen-Johansson Disease
2. Patellar Tendinitis (Jumpers or Kickers Knee)
3. Patellar Tendon Rupture
4. Runner’s Knee (Cyclist’s Knee)
a. Iliotibial Band Friction Syndrome
b. Pes Anserine Tendinitis or Bursitis