knee Joint

-The Knee Joint is the largest.- Most complicated joint in the body.- Most superficial joint.- Hinge type of synovial joint.

Introduction

knee is essentially made up of three bones

femur tibia Patell

a

It consists of 3 Joints within a single synovial cavity :

- Medial Condylar Joint : Between the medial condyle “of the femur” & the medial condyle “of the tibia” .

- Lateral Condylar Joint : Between the lateral condyle “of the femur” & the lateral condyle “of the tibia” .

- Patellofemoral Joint : Between the patella & the patellar surface of the femur .

Articulation , Articular surfaces , and stability of the knee joint

The articulating surfaces of the knee joint are characterized by their large size and their complicated and incongruent shape. The knee joint consists of three articulation:

- Two femorotibial articulation ( lateral and medial ) between the lateral and the medial femoral and tidial condyles.

- One intermediate femoropatellar articulation between the patella and the femur.

- The fibula is not involved in the knee joint .

The stability of the knee joint depends on :

1- the strength and the action of the surrounding muscles and their tendon and2- the ligaments that connect the femur and tibia.

Of these supports, the muscles are most important therefore many sport injuries are preventable through appropriate conditioning and trainig. The most important muscle in stabilizing the knee joint is the large quadriceps femoris particularly the inferior fibers of the vastus medialis and lateralis.

Joint Capsule

A joint capsule is a piece of tissue that surrounds a synovial joint. Its purpose is to hold the synovial fluid of the joint in place, as well as to provide an envelope for the entire joint. The capsule provides an important function to all synovial joints, but it can cause problems, such as frozen shoulder, osteoarthritis, and inflamed plica syndrome, when not functioning properly.

The most common type of joint in the human body is the synovial joint, which contains fluid that helps to lubricate movement. Fibrous joints do not contain either synovial fluid or a joint capsule. Joints containing this fluid can perform a number of different actions, including abduction, extension, and rotation.

Synovial joints appear in the body in a number of different forms. For example, the elbow is a simple hinge joint, while the hip is a more complicated ball-and-socket joint that allows a greater range of movement. Joint capsules are present in all of these joints.

The capsule is made up of two separate layers. The first is an outer layer that contains a fibrous, colorless tissue. The second, inner layer is often called the synovial membrane. Both of these layers need to be in a healthy state in order for the joint to move as it should.

The knee joint capsule allows the full knee to have flexion, or bending, motion due to the folds in the capsule. The joint capsule is made up of the patella, which is within the anterior capsule, as well as the tibia and the femur. The patella is also known as the kneecap. The capsule is held together with ligaments that help with the range of motion. The capsule has synovial fluid, or fluid found in the cavities of synovial joints, that will circulate around the patella, tibia, and femur. Its posterior aspect, or back part of the structure, is stronger and thicker. It makes the person, when standing, more stable and able to balance. The knee joint capsule provides static stabilization for the knee, which is unstable due to its bony configuration. The knee joint itself has two nearly flat surface bones. These surface bones lie on one another as a primary articulating surface. It is the capsule that provides the knee joint its movement.

Extracapsular Ligament of knee joint

1- Patellar Ligament - the distal part of the quadriceps tendon. - Strong. - thick fibrous band. - is the anterior ligament of knee joint. - Laterally, it receives the medial and lateral patellar retinacula,

aponeurotic expansion of the vastus medialis and lateralis and overlying deep fascia.

2- Fibular collateral ligament- Extends inferiorly from the lateral epicondyle of the femur to the

lateral surface of the fibular head

3- Tibial collateral ligament- Extends from the medial epicondyle of the femur to the medial

condyle and the superior part of the medial surface of the tibia

4- Oblique popliteal ligament: - recurrent expansion of the tendon of the semimembranosus. - it arises posterior to the medial tibial condyle.- passes superolaterally toward the lateral femoral condyle. - with the central part of posterior aspect of the joint capsule.

5- The Arcuate Popliteal Ligament:- strengthens the joint capsule posterolaterally.- It arises from the posterior aspect of the fibular head, passes

superomedially over the tendon of the popliteus , and spreads over the posterior surface of the knee joint.

- Its development is related to the presence and size of a fabella in the proximal attachment of the lateral head of gastrocnemius.

- Both structures are thought to contribute to stability of the knee.

Intra-Articular ligaments Cruciate ligaments

The anterior cruciate ligament:- the weaker of the two cruciate ligaments .- arise from the anterior intercondylar area of the

tibia , just posterior to the attachment of the medial meniscus .

- the ACL has a relatively poor blood supply.- it extends superiorly , posteriorly and laterally to

attach to the posterior part of the medial side of the lateral condyle of the femur

- it also prevents posterior displacement of the femur of the tibia and hyperextension of the knee joint .

The posterior cruciate ligament :- the stronger of the two cruciate ligaments. - arises from the posterior intercondylar area of the tibia - the PCL passes superiorly and anteriorly on the medial

side of the ACL to attach to the anterior part of the lateral surface of the medial condylar of the femur

- the PCL limits anterior rolling of the femur on the tibia plateau during extension converting it to spin.

- it also prevents anterior displacement of the femur on the tibia or posterior displacement of the tibia on the femur and helps prevent hyperflexion of the knee joint.

Menisci Of Knee Joint

The knee joint is the most complex and remarkable joint in the body.

The knee’s menisci are two half-moon, wedge

shaped pieces of cartilage (the lateral and medial meniscus), acting as lubricant and elastic buffer, distributing forces evenly between the femur (upper leg) and tibia (lower leg) in the knee joint.

- Their attachment to the intercondylar area of the tibia and tibia attachments of the cruciate ligaments.

- The BAND like tibial collateral ligament is attached to the medial meniscus.

- The CORD like fibular collateral ligament is sparated from lateral meniscus.

- The posterior meniscofemoral ligament attaches the latreral meniscus .

- Flexion and Extension are the MAIN knee movement.

Movement of the knee

muscle movement

Biceps femorisSemitendinosusSemimembranosusGracilisSartoriusPopliteus

Flexion 120°-150°

Quadriceps femoris Extension 5°-10°

Biceps femoris External rotation 30°-40°

Sartorius Gracilis

Semtendinosus Popliteus

Semimembranosus

Internal rotation 10°

Blood supply of the knee joint

The Femoral artery and the popliteal artery forms artery network surrounding the knee joint ,There are 6 main branches :

1. Superior medial genicular artery

2. Superior lateral genicular artery

3. Inferior medial genicular artery

4. Inferior lateral genicular artery

5. Descending genicular artery branch from the femoral artery

6. Recurrent branch of anterior tibial artery

The medial genicular arteries penetrate the knee joint

Branch from popliteal artery

Nerve Supply of knee joint

Innervation of the knee

The nerves around the knee are motor (move muscles) and sensory (allow you to feel what is happening). The sensory nerves supply the joint itself as well as the skin over the knee. Many muscles have both motor and sensory functions.

While there is a great deal of variation in the nerves, essentially there are the nerves at the back of the knee and the nerves at the front of the knee. The nerves that supply sensation to the back of the knee joint itself are the posterior (back) articular (joint) branches of the tibial and obturator nerves.  The equivalent nerves in the front are the articular branches of the femoral, common peroneal and saphenous nerves. This is different to the pattern of skin sensation nerve supply

The obturator

(L2,3,4)  supplies the adductor muscles on the inner side of the thigh. These are the muscles that squeeze the knees together. This nerve also supplies the hip and sometimes pain from the hip can be felt as pain on the inner side of the knee. For this reason the hip must always be examined if the cause of the pain in the knee is not obvious.

The femoral nerve (L2,3,4) supplies the main muscles at the front of the thigh (motor) as well as the knee joint (sensory). Damage to the femoral nerve results in weakness of the quadriceps muscles (which straighten the knee). The saphenous nerve is a sensory continuation of the femoral nerve (supplies feeling to the inner aspect of the foot).

Femoral nerve

The femoral nerve (L2,3,4) supplies the main muscles at the front of the thigh (motor) as well as the knee joint (sensory). Damage to the femoral nerve results in weakness of the quadriceps muscles (which straighten the knee). The saphenous nerve is a sensory continuation of the femoral nerve (supplies feeling to the inner aspect of the foot).

The sciatic nerve

 (L4,5, S1,2,3) is a large nerve which runs down

the back of the leg. It is made up of the tibial and common peroneal nerves which branch at different levels of the leg in different people. The sciatic nerve splits into the tibial and common peroneal nerves above the knee.  The tibial nerve supplies the hamstring muscles (which bend the knee). It also supplies the muscles in the back if the calf (gastrocnemius and soleus).  The common peroneal nerve supplies the front compartments of the leg including the peroneal muscles.

The tibia nerve

 

is the larger of the two branches of the sciatic nerve and runs down the back of the knee. The common peroneal nerve separates from the tibial portion of the sciatic nerve just above the knee and then follows behind the hamstring on the outer side of the leg to top part of the smaller done in the leg called the fibula.  The nerve then goes past the head of the fibula, winds round the neck of the fibula and dives deep into the muscles to divide into the superficial (closer to the surface) and deep (further inside) peroneal nerves.

Any nerve that goes past the knee joint gives off a sensory branch to the knee joint.Nerve injury around the knee is rare compared to meniscal, chondral or ligamentous injuries. Nerve releases are occasionally needed but are rare compared to arthroscopic and reconstructive surgery of the knee

The common peroneal nerve is one of two major branches of the sciatic nerves within the buttocks and into the thighs, along with the tibial nerves. The many branches of these nerves supply nerve impulses to and from the muscles and skin in the hip joints and thighs, the lower legs, feet and most of the skin below the knee.

Common peroneal nerve

Saphenous nerve

 

The saphenous nerve long branch of femral nerve, about the middle of the thigh, gives off a branch which joins the subsartorial plexus.At the medial side of the knee it gives off a large infrabatellar branch , which pierces the Sartorius and fascia lata, and is distributed to the skin in front of the patella.Below the knee, the branches of the saphenous nerve (medial crural cutaneous branches) are distributed to the skin of the front and medial side of the leg, communicating with the cutaneous branches of the femoral, or with filaments from the obturator nerve.

Subcutaneous

Prepatellar Bursae

Popliteus Bursae

Suprapatellar

Bursae

Deep Infrapatel

lar Bursae

Subcutaneous

Infrapatellar Bursae

Anserine Bursae

Semimembranosus Bursae

Gastrocnemius

Bursae

Comments Locations Held in position by

articular genu muscles; communicate freely with (superior extension of) synovial

cavity of knee joint.

Between femur & tendon of quadriceps

femoris ..

Comments Locations Opens into synovial cavity of knee joint inferior to lateral

meniscus

Between tendon of Popliteus & lateral

condyle of tibia.

Comments Locations Area where tendons of these muscles attach

to the tibia; resembles goose’s foot.

Separates tendons of Sartorius, gracilis & semitendinosus from

tibia & tibial collateral ligament .

Comments Locations An extension of

synovial cavity of knee joint .

Deep to proximal attachment of tendon

of medial head of Gastrocnemius .

Comments Locations Related to distal attachment of

Semimembranosus .

Between medial head of Gastrocnemius & Semimembranosus

tendon.

Comments Locations Allows free movement

of skin over patella during movements of

leg.

Between skin & anterior surface of

patella.

Comments Locations Helps knee withstand

pressure when kneeling.

Between skin & tibial tuberosity.

Comments Locations Separated from knee joint by infrapatellar

fat pad .

Between patellar ligament & anterior

surface of tibia.

Applied Genu Varum & Genu Valgum

The femur is placed diagonally within the thigh. whereas the tibia is almost vertical within the leg, creating an angle, the Q-angle, at the knee between the long axes of the bones. The Q-angle is assessed by drawing a line from the ASIS to the middle of the patella and extrapolating a second (vertical) line through the middle of the patella and tibial tuberosity .

Genu varum

The Q-angle is typically greater in adult females, owing to their wider pelves. A medial angulation of the leg in relation to the thigh, in which the femur is abnormally vertical and the Q-angle is small, is a deformity called genu varum (bowleg) that causes unequal weight distribution.Excess pressure is placed on the medial aspect of the knee joint, which results in arthrosis (destruction of knee cartilage).

Genu valgum A lateral angulation of the leg in relation to the thigh (exaggeration of knee angle) is genu valgum

Consequently, in genu valgum, excess stress is placed on the lateral structures of the knee. The patella, normally pulled laterally by the tendon of the vastus lateralis, is pulled even farther laterally when the leg is extended in the presence of genu varum so that its articulation with the femur is abnormal.

Patellar Dislocation

patellar dislocation - patella is dislocated, it nearly always dislocation laterally. - most common in women. - the tendency toward lateral dislocation is normally

counterbalanced by the medial, more horizontal pull of powerful vastus medialis.

- in addition, the more anterior projection of the lateral femoral condoyle and deeper slope for the large lateral patellar facet provide a mechanical deterrent to lateral dislocation.

- imbalance of the lateral pull and mechanisms resisting it result in abnormal tracking of the patella within the patellar groove and chronic patellar pain, even if actual dislocation does not occur.

Patellofemoral syndrome 

Pain deep to the patella often results from excessive running , especially downhill.

- This type of pain is often called "runner' knee".- The pain results from repetitive microtrauma caused by abnormal tracking of the patella relative to the patellar surface of the femur, a condition know as the patellofemoral syndrome.

In some cases , strengthening of the vastus medialis corrects "patellofemoral dysfunction"

This muscle tends to prevent lateral dislocation of the patella resulting from the Q angle because the vastus medialis attaches to and pulls on the medial border of the patella .Hence, weakness of the vastus medialis predisposes the individual to the patellofemoral dysfunction and patellar dislocation.

Knee joint injury- common(low placed, mobile, weight bearing and

serving as fulcrum bet 2 levers.

- Stability depends on the associated ligament and surrounding muscles.

- it’s essential for everyday activities (stand ,walk..& climbing stairs) and considers main joint for sports( jump, run and change direction).

- Knee is susceptible to injuries because is mobile .

- Common injuries in contact sports are(ligament sprains).(when the foot fixed in ground,if force is applied against knee,when foot cannot move.

- (TCL) & (FCL) are tightly stretched when .. & preventing disruption the knee from sides.

- (TCL) attachment to medial meniscus.

- Injury is frequently caused by a blow to lateral side of extended knee or excessive lateral twisting of flexed knee , (TCL) may be and\or detaches medial.m

from joint capsule , this common in athletes.

- (ACL ) anterior cruciate ligament, it’s serves as axis for rotatory

movement knee, is taut during flexion, may also tear subsequent to

rupture of (TCL) creating“unhappy triad. ”

BASIC

Your thigh bone (femur) and lower leg bones (tibia and fibula) meet in the knee joint and are held together by tissue called ligaments. In the middle of the knee are two ligaments called the

-anterior (front) cruciate ligament (ACL) - posterior (back) cruciate ligament (PCL)

anterior cruciate ligament

Function of (ACL)- prevents the tibia

from slipping forward against the

femur.

- prevents the femur from moving too far backward over the

tibia

BASIC of (ACL)

Normal action

Injury to the ACL

This injury causes the free tibia to slide anteriorly under the fixed femur, known as the anterior drawer sign.

Posterior view of the knee

Function of (PCL)- prevents the

femur from moving too far forward over the tibia.

- knee’s basic stabilizer and is almost twice as

strong as the ACL

BASIC of (PCL)

normalInjury to the PCL

This injury allow the free tibia to slide posteriorly under the fixed femur, known as the posterior drawer sign.

Most athletic PCL injuries occur during a fall on the flexed (bent) knee with the foot plantar flexed (the toes pointing down with the top of the foot in line with the front of the leg). The shin (tibia) strikes the ground first and is pushed backward

•Is endoscopic examination that allow visualization of the interior of the knee joint

cavity with minimal disruption of tissue .

•Portals : arthroscope and one or more additional canula are inserted through tiny incisions.

*The scenod canula is for passage of specialized tools ( e.h, manipulative forceps ) or equipment for trimming , shaping , removel

damage tissue .

*In knee arthroscopy can using local or regional anesthesia.

*this technique allows removal of torn menisci , loose bodies in the joint , debridement in advanced case of arthitis ligment repair or replacement.

*Druing arthroscopy , the articular cavity of the knee must be treated essentially as two separate ( medial and lateral ) femorotibial articulation owing to the imposition of synovial fold around

the cruciate ligment .

Aspiration Of Knee Joint

Infection Joint effusion

Lacerations of the anterior thigh ( involve suprapatellar bursa )

Fractures (distal end of femur)

Synovial Fluid

( Inflammation)

Performing Direct Aspiration of the knee joint:- Patient setting ( table).- knee flexed.- Joint should be approached laterally.- Three bony point as Landmarks for needle insertion

(+drug injection )

1- Apex of patella 2- Lateral epicondyle of femur 3- anterolateral tiblial (Gerdy) tubercle.

Bursitis in the knee region

Bursitis : is a painful condition that affects the small fluid-filled pads called bursae. that act as Facilitate the movement between bones and the tendons and muscles near of the joints.

There are three bursas in the knee region : prepatellar- inrfapatellar( is divided into deep and superficial)- suprapatellar.

(Deep)

Infrapatellar bursa ( superficial)

Prepatellar: Caused by friction between the skin and patella,

and may be injured by compressive forces resulting

frome direct blow or from falling on the flexed knee.

If the inflammation is chronic, the bursa become distended with fluid and forms a swelling anterior to the knee.

Subcutaneous infrapatellar :Is caused by excessive friction between the skin and the tebia tuberosity. Deep infrapatellar:

Results in edema between the patellar ligament and the tibia, superior to the tibial tuberosity.

Patellar tendon(ligament)

Tibial tuberosity

The inflammation is usually caused by overuse and subsequent friction between the patellar tendon and the structures posterior to it.

The Structures posterior of the tendon is:The infrapatellar fat pad and tibial.

Suprapatellar bursitis:Penetrating wounds may result in suprapatellar bursitis, an infection caused by bacteria entering the bursa frome the torn skin.

The infection may spread to the cavity of the knee joint, causing localized redness and enlarged popliteal and inguinal lymph nodes.

are abnormal fluid filled sacs of synovial membrane in the region of the popliteal fossaa.

popliteal cyst is almost always a complication of chronic knee joint effusion

Popliteal cyst

The cyst may be a herniation of the gastrocnemius or semimembranosus bursa through the fibrous layer of the joint capsule

into the popliteal fossa .

Communicating with the synovial cavity of knee joint by a narrow stalk.

Synovial fluid may also escape from knee joint or a bursa around the knee and collect in the popliteal fossa .

Here it forms a new synovial-lined sac ,or popliteal cyst .

Popliteal cyst are common in children but seldom cause symptoms .

In adults , popliteal cysts can be large , extending as far as the midcalf , and may interfere with knee movement

Knee replacement

Knee replacement, or knee arthroplasty, is a surgical procedure to replace the weight-bearing surfaces of the knee joint to relieve pain and disability.

Medical Uses:a. Knee replacement surgery is most commonly performed

in people with advanced osteoarthritis and should be considered when conservative treatments have been exhausted.

b. Total knee replacement is also an option to correct significant knee joint or bone trauma in young patients.

c. Similarly, total knee replacement can be performed to correct mild valgus or varus deformity.

Risks:a. The most serious complication is infection of

the joint, which occurs in <1% of patients. b. Deep vein thrombosis occurs in up to 15% of

patients, and is symptomatic in 2–3%. c. Nerve injuries occur in 1–2% of patients. d. Persistent pain or stiffness occurs in 8–23% of

patients. e. Prosthesis failure occurs in approximately 2%

of patients at 5 years.