KNEE JOINT

 

BONES

1. Distal Femur

*The lateral and medial epicondyles are located distal to the femur and are the attachment site of the collateral ligaments.
*Condyles are asymmetrical, providing extension. While the lateral epicondyle is straighter in the sagittal, the medial epicondyle is inclined to the mountain in the sagittal. Also, the medial epicondyle is the main cause of the asymmetry in the knee.
*Lateral facet inclination is important in patella stabilization.

 

2.Proximal Tibia-Fibula

*The lateral facet surface here is slightly convex; the medial facet surface is concave and wider than the lateral one.
*Tuberositas Tibia is the attachment site of Quadriceps femoris.
*Fibula is the attachment site of Lateral Collateral Ligament/LCL and Biceps femoris muscle.

CLINICAL = Inflammation and hypertrophy occur as a result of the force applied by the quadriceps femoris tendon to the Tuberositas tibia. This condition is called Osgood-Schlatter disease.

 

3. Patella

*It is the largest sesamoid bone.
*It is the proximal attachment site of the patellar tendon.
*The posterior face is concave while the anterior face is convex.
*The lateral facet is wider and concave than the medial. (The lateral facet is convex in the distal femur!)
*Medial facet may differ.

 

Angle of Inclination = Since the tibia is proximal and the joint is horizontal, there is an angulation of 170-175 degrees laterally. Angle below 170 degrees in the lateral is “GENU VALGUM”, while angulation above 180 degrees in the lateral is called “GENU VARUM”.

 

 

JOINTS

1. Tibiofemoral Joint

*The convex femur is the joint between the condyles and the concave tibia.
*The resting position of the joint is 25-30 degrees of flexion.
*The closed-pack position of the joint is full extension and external rotation.
*The stability of this joint is not provided by bone harmony. Stability is provided by the forces created by structures such as muscles, ligaments, capsule, meniscus and body weight.
*130-150 degrees of flexion in the joint, 15 degrees of internal rotation and 30 degrees of external rotation when the knee is in 90-degree flexion, that is, a total of 45 degrees of axial rotation is performed. It is suggested that 6-7 degrees of lateral flexion occurs, although it is not certain in recent studies.

 

DETAIL1 = When standing up from the full squatting position (in the extension of the femur on the tibia), the femoral condyles roll forward and the slip occurs backwards.

DETAIL2 = In the last 10 degrees of extension;
>> If the femur is fixed, the tibia will rotate externally.
>> If the tibia is fixed, the femur rotates internally.
The primary factor in the realization of these two events is the medial condyle of the femur.

 

DETAIL3 =In the first 20 degrees of flexion; The femoral condyles are rounded on the tibia.
After 20 degrees of flexion, the femoral condyles slide on the tibia. This slip occurs more in the lateral femoral condyle.

 

2. Patellafemoral Joint

*It is the joint between the convex patella and the concave femur.
*In flexion, the patella makes 5-7 cm distal gliding on the femur.
*There is some medial translation at the beginning of the flexion.
*When it reaches 30 degrees of flexion, the patella starts to gliding laterally and this event continues until 45 degrees of flexion.
*In extension, the patella has little or no connection with the femur.
*The resting position of the joint is full extension/5 degree flexion.
*The closed-pack position of the joint is full flexion.

 

Q Angle = The angle between the vertical line of the patella midpoint and the Quadriceps force vector resultant. 13-15 degrees is considered normal.

 

LIGAMENTS

1. Medial Collateral Ligament/MCL

*Valgus creates resistance to knee extension and axial rotation. It is injured as a result of exposure to valgus stress and severe hyperextension of the knee while the foot is fixed on the ground.

2. Lateral Collateral Ligament/LCL

*Varus stress creates resistance to knee extension and axial rotation. When the foot is on the ground, it is injured as a result of exposure to varus stress and severe hyperextension of the knee.

 

3. Anterior Cruciate Ligament/ACL

*Most fibers resist extension. Excessive anterior translation of the tibia prevents posterior translation of the femur.
* It creates resistance against excessive varus, valgus and axial rotation.
* Exposure to valgus stress while the foot is in contact with the ground,
*large axial rotation torque applied to the knee while still in the same position,
*Exposure to valgus stress and applied large axial rotation torque, which includes strong Quadriceps activity when the knee is in full or nearly full extension,
*Severe hyperextension of the knee
As a result, injuries to the ACL occur.

4. Posterior Cruciate Ligament/PCL

*Most fibers create resistance in flexion.
* While preventing excessive posterior translation of the tibia, it prevents anterior translation of the femur.
* As in ACL, it also creates resistance to excessive varus, valgus and axial rotation.
*As a result of falling on the knee in full flexion, PCL injuries are encountered. During this fall, the ankle is in plantar flexion and the first contact with the ground is the proximal structure of the tibia.
*When the foot is in contact with the ground and especially if the knee is in the flexion position, excessive axial rotation, varus and valgus torque can also cause damage.
*The PCL may be damaged as a result of conditions that force the tibia to posterior translation or the femur to anterior translation.
*Finally, the other mechanism of injury is severe hyperextension of the knee that can cause a large gap on the posterior surface of the joint.

 

MENISCUS

* It has a crescent shape and fibrocartilage feature.
*The medial meniscus is oval. Its outer border is attached to the MCL and the capsule.
*The lateral meniscus is more circular and attaches only to the capsule.
*Quadriceps and Semimebranosus are attached to both meniscus.
*1/3 peripheral parts are connected to knee arteries by capsule anastomosis. 2/3 are avascular, they are fed with synovial fluid.
* They reduce the compressive stress on the tibiofemoral joint.
* Stabilizes the knee during movement.
*Provides gliding in the articular cartilage.
*Provides proprioception.

*Among the most common injuries to the knee, responsible for 50% of ACL injuries.
*The medial meniscus is injured twice as often.
*Increased valgus force creates stress on the MCL and posterior medial capsule, which damages the medial meniscus due to its connections.
*In addition, the risk of medial meniscus tear; knee joint malalignment and ACL instability increase.
* In general, difficult axial femoral rotation in the flexion position causes tears under load. Again, the same situation can lead to dislocations.

 

 

MUSCLES

1) M. Quadriceps Femoris

?Rectus femoris = Spina iliaca anterior inferior
?Vastus lateralis =Linea aspera and trochantor major
?Vastus intermedius =Anterior aspect of the femur
?Vastus medialis =Starting from the linea aspera and crista supraepicondylus medialis, they end in the tuberositas tibia through the ligamentum patella. The innervation of these four muscles that make up the quadriceps is provided by the N.femoralis(L2-4). Only RECTUS FEMORIS makes the thigh flexion.

 

2) M.Tensor Fascia Lata/TFL

*Starting from the cias and ending in the lateral condyle of the tibia. It is innervated by the N. Gluteus superior (L4-S1). It abducts when the thigh is in flexion. At the same time, while making the thigh flexion, it makes the leg extend.

3) M. Sartorius

*Starting from the sias and ending on the inner side of the tibia. It is innervated by N.femoralis(L2-4). It makes the thigh flexion, abduction and external rotation. It is also responsible for flexion and internal rotation of the leg.

 

4) Hamstrings

?Biceps Femoris =Caput longum tuber ischiadicum, starting lateral to the caput breve linea aspera and ending in the lateral condyle of the caput fibula and tibia. The caput longum is innervated by the N. Tibialis (L4-5 and S1-3). Caput breve part is innervated by N.Peroneus Communis (L4-5).
While extending the thigh, it makes the leg flexion and external rotation.
?Semimebranosus =Starting from the tuber ischiadicum and ending in the medial condyle of the tibia. It is innervated by the N.tibialis(L4-5,S1-3). It makes the leg flexion and internal rotation while extending the thigh.
?Semitendinosus =Starting from the tuber ischiadicum and ending on the proximal inner side of the tibia. It is innervated by the N.tibialis side. While extending the thigh, it makes the leg flexion and internal rotation.

 

5) M. Gracilis

*Starts from the pubis and ends on the proximal inner side of the tibia. It is innervated by N.Obturatorius. It makes the leg flexion and internal rotation while adduction of the thigh.

 

6) Popliteus

*Starting from the lateral condyle of the femur and ending on the posterior surface of the tibia. It is innervated by the N. Tibialis. It makes the leg weakly flexed. It is the key muscle of the knee.

 

7) Gastrocnemius-Soleus

*The lateral and medial condyle of the femur starts from the caput fibula and ends at the Calcaneal tendon/Achilles tendon. It is innervated by the N. Tibialis. The nerve level is L4-5/S1-3. Its primary task is to plantar flexion of the foot. In addition, it makes the leg flexion.

 

 

BLOOD AND NUTRITION

*Descending genicular artery, which is a branch of the lateral circumflex femoral artery
* Medial inferior and superior genicular arteries arising from the popliteal artery, lateral inferior and superior genicular arteries
*Mid genicular artery
*Anterior and posterior tibial arteries, which arise from the anterior tibial artery, provide blood supply.
*The blood supply of the patella is provided by the anastomoses of these arterial groups.