The Knee Flashcards
- One of the most injured joints in the body
- Supported mainly by muscles and ligaments with NO bony stability
- The largest joint in the body
- Flexion, extension and rotation as an accessory motion to extension
The Knee
Note: the articular surface of the femoral condyles is much larger than the articular surface of the tibia… therefore:
As the knee is going from flexion into extension, the femur must ________posteriorly as it _________s on the tibia (so it does not run out of room to complete extension)
- GLIDE
- ROLL
Note: the articular surface of the medial condyle is larger than that of the lateral condyle … therefore:
- The medial condyle of the femur must also glide posteriorly to use all of its articular surface
- This cause the femur to spin medially in the last few degrees of WB extension in closed chain action
In the screw home mechanism in the weight bearing position (closed chain kinetic activity), the femur rotates _________on the tibia as the knee moves into the last few degrees of knee extension
medially_
In the non-weight bearing position (open chain kinetic activity), the tibia must rotate ________ on the femur and the last few degrees of extension will LOCK the knee into extension
laterally
- To unlock the knee in an open chain kinetic activity, the femur must rotate laterally on the tibia
- This accessory motion limits the knee from being a TRUE hinge joint but knee rotation will not be considered a measureable joint motion
Screw Home Mechanism
The articulation between the femur and patella is the ______________ joint
Patellofemoral Joint
The patella serves to increase the mechanical advantage of the ___________muscle and to protect the knee joint from harm
quadriceps
the patella
- The moment arm is____________ due to the line of pull the patella adds to the quadriceps
- Remember…the perpendicular distance from the muscle line of action to the joint axis
- Without the patella, this moment arm would be shorter and the joint would be at a disadvantage
lengthened
- Also known as the Q-angle or the patellofemoral angle is the angle between the patellar tendon and the rectus femoris
- Determined by drawing a line from the ASIS to the midpoint of the patella and from the tibialtuberosity to the midpoint of the patella
- Normal ranges are 13-18 degrees and it is measured in knee extension
- Larger in women due to their *larger by nature* pelvis
- Patellofemoral pain syndrome (PFPS) and other patellar tracking problems can occur because of this
Quadriceps Angle
most posterior of the tarsal bones
Known as the heel, the gastrocnemius & soleus attach here
Calcaneus
- Lateral to and smaller than the tibia
- This bone gives the rounded shape to the lower leg
- Not a part of the knee joint but articulates with the tibia and glides as an accessory motion on the tibia during knee ROM
- Larger role of motion at the ankle
Fibula
attaches to the anterior surface of the intercondylar eminence and just medial to the medial meniscus and runs superiorly and posteriorly to the lateral condyle of the femur
ACL
attaches to the posterior surface of the intercondylar eminence and runs superior/inferiorly to the medial side of the ACL and attaches to the medial condyle of the anterior femur
PCL
Both ACL & PCL provide stability in the ______ plane of motion
Sagittal plane
ACL –prevents
excessive hyperextension
When the knee is slightly flexed, it limits anterior translation of the tibia on the femur
PCL – keeps the femur from_____________on the tibia. Tightens during flexion and is less injured overall than the ACL
displacing anteriorly
flat, broad ligament that provides stability to the medial side of the knee
Fibers of the medial mensicus are attached to this ligament and result in frequent tearing of the meniscus
MCL
Medial collateral ligament
round and cordlike, provides stability to the lateral side of the knee (book states medial – it protects from a blow to the medial knee)
These ligaments provide stability in the frontal plane
LCL
lateral collateral ligament
two half moon, wedge shaped fibrocartilagenous disks located on the superior surface of the tibia
Medial and Lateral Meniscus
reduce friction and there are approximately 13 at the knee joint
- Due to the tendinous insertions around the knee
Bursae
Contains important structures
- Tibial nerve
- Common peroneal nerve
- Popliteal artery
Popliteal Fossa
Borders of popliteal fossa
- Superior/medial – semitendinosus/semimembranosus
- Superior/lateral – biceps femoris
- Inferior - gastrocnemius
goose/duck foot
- Say grace before tea
- Sartorius
- Gracilis
- Semitendinosus
Pes Anserine
Patellar tendonitis
Jumper’s Knee
popliteal cyst
Baker’s cyst –
housemaid’s knee
Prepatellar bursitis –
Muscles of the Knee(9)
- Rectus femoris
- Vastuslateralis
- Vastusmedialis
- Vastusintermedius
- Semimembranosus
- Semitendinosus
- Biceps femoris
- Popliteus
- Gastrocnemius
- One of the more challenging disorders to treat for both the patient and the PT/PTA
- Not always easy to identify this region as the source of the patient’s complaints or to isolate causes of the pain
- Understanding the biomechanics of the knee and the lower extremity is essential for successful management
Patellofemoral Problems
Signs and Symptoms:
- Aching pain in the front of the knee, typically of gradual onset
- Can be “behind” the knee
- Complaints of the knee “giving way”
- Thought of a protective response to pain caused by an aggravating factor such as climbing stairs
- Grinding noises in the knee
- Crepitus, typically benign
- Pain with walking up stairs, squatting, and running and other bent-knee weight bearing activities
- Pain with prolonged sitting
- Mild swelling, if any
- Excessive foot pronation, tight hip internal rotators/weak hip external rotators alter the pull of the quadriceps on the patella
- Patellar tilt, seen with palpation
Patellofemoral Problems
- Inflammation of the patellar tendon, often seen with jumping activities
- Referred to as Jumpers Knee
- Seen with sports that require fast running and abrupt changes in direction
Patellar Tendonitis
Signs and Symptoms:
- Anterior knee pain
- Local, point tenderness
- Small amount of local swelling
Patellar Tendonitis
Inflamed and painful infrapatellar fat pad
Often confused with patellar tendonitis
Signs and Symptoms:
- Pain just below the patella
- Movement of the knee typically aggravates the symptoms
- Tender to palpation
- Swelling in the anterior knee
Fat Pad Syndrome
- Typically caused by a blow to the outside of the knee or a high energy twisting maneuver
- Forces result in stretching and a valgus force on the medial tibiofemoral joint
- Graded on a system of I -> III
Medial Collateral Ligament Sprain (MCL)
- LCL is on the lateral side of the knee and is not frequently involved with high-level activities
- Injured by a blow to the medial side of the knee, resulting in a varus (from inside) stress to the knee joint
- Confirmed with tenderness to palpation as well as possible laxity with a varus
Lateral Collateral Ligament Sprain (LCL)
Symptoms:
- Mild tenderness over the affected ligament
- Usually no swelling
- For an MCL sprain, when the knee is bent to 30 degrees and force is applied to the outside of the knee, pain is felt, but there is no laxity/looseness
Grade I Ligament Sprain
Symptoms:
- For MCL, significant tenderness on the inside of the knee for the medial collateral ligament
- Some swelling seen over the ligament
- When the knee is stressed, there is pain and laxity in the joint and there is a definite end point/end feel to the joint
Grade II Ligament Sprain
Symptoms:
- There is a complete tear of the ligament
- Pain can very and is sometimes less than that of a grade II sprain
- When the knee is stressed, there is significant joint laxity
- The patient might complain that there is significant instability or “wobbly” feeling in the joint
Grade III Ligament Sprain
- Injury to the ACL can be from contact or noncontact causes
- Situations that place a loaded, weight bearing knee in a combined position of flexion, valgus and rotation of the tibia on the femur can rupture the ACL in a noncontact manner
- Rapid changes in direction
- Once the ACL is stretched or ruptured, it will not heal on its own
- Sometimes accompanied by medial meniscus tears and MCL sprains
- Unhappy Triad
- The ACL and PCL do not follow the same grading scale as for MCL and LCL sprains
- They are either damaged or not damaged – there is no middle ground
Ruptured Anterior Cruciate Ligament
Signs and Symptoms:
- “Pop” in the knee is either felt or heard by the patient
- Followed by rapid effusion/swelling in the joint cavity
- Nausea immediately after the injury
- Positive special testing for ligament instability must be completed within 5 minutes of injury otherwise, the test will be invalid due to muscle guarding
- Diagnosis by a physician in conjunction with an MRI (magnetic resonance)
Ruptured Anterior Cruciate Ligament
- Account for 3-20% of all knee injuries
- Most injuries occur from athletics, MVAs or industrial accidents
- Athletic – fall onto a flexed knee with foot in plantar flexion
- Hyperextension
- Dashboard injuries
Posterior Cruciate Ligament Tear
Signs and Symptoms:
- Pain
- Positive “Sag” Test – giving the illusion when the knee is flexed that it is bending backwards
- Positive diagnostic imaging on an MRI
Posterior Cruciate Ligament Tears
- Menisci help to make a more concave surface for the condyles to rest and glide on and make the knee more stable
- Medial meniscus tears more easily than the lateral because it is attached to the medial collateral ligament and is more restricted during movement
- Lateral meniscus is attached only at the back of the knee and moves more freely as the knee is bent and straightened
- Torn when twisted suddenly and one or more menisci become caught between the knee
Meniscus Tears
Signs and Symptoms:
- Isolated tears develop mild swelling slowly over several hours or more
- Pain
- Popping
- Locking
- Giving way of the knee
Meniscus Tears
- Knee is subjected to sports-induced trauma at the center of bone growth in skeletally immature athletes.
- Epiphyseal plates are zones of cartilage cells from which new bone is formed
- The joint capsule and ligaments near these growth plates are 2->5x stronger than the growth plate itself
- Because the epiphysis is responsible for bone growth, injuries involving this area may alter the length of the involved bone
Epiphyseal Injuries (growth plate)
- A group of symptoms involving the tibial tubercle epiphysis
- Most likely to involve males age 12-16 and females 10-14
- Traction of the quadriceps muscle inflames and irritates the layers of the tibial tubercle, causing it to swell
- If the femur is growing faster than the quadriceps, the quadriceps will exert undue pressure on the growth center of the tibia
Osgood-Schlatter Condition
Signs and Symptoms:
- Pain over the tibial tubercle
- Swelling over the tibial tubercle
- Weakness in the quadriceps muscle group
- Increased pain and swelling with activity
- Visible lump
- Pain to the touch over the affected area
Osgood-Schlatter Condition
- Inflammation of the band that begins at the hip and extends to the knee on the outside of the leg
- Irritation usually occurs over the outside of the knee joint at the lateral epicondyle
- Where the IT band crosses bone and muscle at this joint
- Should be smooth and gliding motion
- When inflamed, motion becomes painful and guarded
- People who suddenly increase their level of activity are prone to developing
Iliotibial Band Syndrome
- Typically a result of high-energy trauma
- Fractures vary in location and severity
- Patellar fractures are a result of direct impact to the anterior knee
- Knee strikes hard ground or some other hard surface
- Distal femoral and proximal tibial fractures may occur from violent twisting injuries such as falls from heights
Fractures
What is involved in the terrible triad?
- Medial Meniscus
- Anterior Cruciate Ligament,
- Medial Collateral Ligament.
MAM
Normal ranges of the Q-angle are between ___&___degrees and it is measured in knee____________.
- 13-18
- extension
