Disorders of the knee Flashcards
Why are knee disorders important?
- Major weight bearing joint
- Required for walking
- Critical for health and fitness
- Reduced mobility
- Predisposition to falls
- Weight gain
- Disability
- Inability to work
- Psychosocial issues
- Depression
- Social isolation
normal knee x-ray
OA of the knee presentation
the typical symptoms of knee osteoarthritis are knee pain, stiffness, sensation of giving way and swelling.
The pain may follow a pattern, for example:
- Knee pain that comes and goes, possibly with a chronic low level of pain punctuated by more severe flare-ups
- Pain precipitated by activities such as bending, kneeling, squatting or climbing stairs
- Pain and stiffness that is worse after prolonged inactivity or rest, such as getting out of bed in the morning
types of deformities associated with knee OA
varus (deviation of the distal component toward the midline; see image below
valgus deformity (deviation away from the midline)
fixed flexion deformity (in which the knee cannot be fully extended)
Risk factors of knee OA
- Age
- Female
- Previous trauma
- Obesity
- Family history of OA
- Rheumatoid arthritis
- Gout
- Septic arthritis
- Haemophilia with hemarthrosis
Treatment of knee OA
- Strengthening exercise to strengthen the vastus medialis muscle and reduce instability
- Analgesis
- Weight loss
- Activity modification
- Surgery (last call)
Septic arthritis of the knee
Septic arthritis is the invasion of joint space by microbes. It can occur elsewhere in the body but is most commonly seen in the knee joint and can present like a knee effusion.
risk factors for septic arthritis of the knee
Risk factors include: increasing age, rheumatoid arthritis, diabetes, immunosuppression, IV drug use and prosthetics in the knee (from a joint replacement).
presentation of septic arthritis
This condition presents with a fever; pain, swelling and erythema around the knee; and a decreased range of motion.
managment of septic arhtitris
A joint aspirate is taken and cultured to determine the bacterial cause of the infection (usually Staphylococcal or Streptococcal bacteria) and then antibiotics are used to treat the infection. If particularly severe, the fluid in the joint may also need to be drained.
how is septic arthritis different to reactive arthritis
- Differs from reactive arthritis, which is sterile inflammatory process that can result from an extra-articular infection e.g. gastroenteritis
microorganism which cause septic arthritis
- Staphylococcus aureus
- Staph epidermidis
- Neisseria gonorrhoeae
- Strep viridans
- Strep pneumoniae
risk factors of septic arthritis
- Age
- Diabetes mellitus
- Rheumatoid arthritis
- Immunosuppression
- Intravenous drug abuse
- Prosthetic joints – biofilm
progosis of septic arthritis
patella fracture
Fractures of the patella are often caused by direct impact or indirect eccentric (not central) contraction of the quadriceps (contraction to straighten the leg when the knee is not straight below the hip but deviated to the side).
patellar fracture most common in
Patella fractures usually present with
usually present with: swelling (due to bleeding at the site of fracture), a palpable defect and an inability to perform a straight leg raise (if patella fracture is displaced).
treatment for a displaced patella
If the patella fracture is displaced, surgery is the most likely option for treatment. In both cases physiotherapy may be required to return the leg to full function, once it can bear weight again.
treatment for undisplaced patella fracture
Treatment of a non-displaced patella fracture is to use a long leg cast or knee immobiliser to allow the patella to remain in the correct position while it heals. In both cases physiotherapy may be required to return the leg to full function, once it can bear weight again.
what do you need to be aware of with patella fractures
Bipartite patella
It is important to bear in mind that the patella exists in two parts in children, so that it can grow properly. This means that in a child presenting with a patella in two parts, it does not always need immobilisation – this decision should be made based on clinical history.
Dislocation/ subluxation of the patella most commonly occurs
Dislocation of the patella most commonly occurs laterally due to internal rotation of the femur on a flexed knee.
cause of dislocation of patella
It most often occurs in athletic teenagers who try to change direction when running on a flexed knee.
presentation of patella dislocation
It usually presents with: severe knee pain, swelling, an inability to straighten the knee and sometimes a ‘popping’ sensation is experienced.
predispostions to patella dislocation
- Weakness of the VMO
- Ligamentous laxity
- Shallow trochlear groove
- Long patellar ligament
- Previous dislocation
Treatment for patella dislocation is
reduction of the kneecap. During reduction pain relief is given. After reduction an X-ray may be done to check the patella is in the correct place and that there is no other damage. The leg will usually be immobilised with a splint initially and physiotherapy may be recommended to aid recovery.
Tibial plateau fractures caused by
- High energy injury
- Mechanism- Axial loading and varus or valgus angulation (abnormal medial or lateral flexion load)
tibial plateau fractures can be
- Uni/bi-condylar
- Fractures affecting the lateral tibial condyle are the most common
with tibial plateau fractures what is always damaged
articular cartilage
tibila plateau fracture results in
- Instability
- Accurate joint surface reduction
- Post-traumatic OA
- Can be associated with meniscal tears and anterior cruciate ligament (ACL) injuries
treatment of tibial plateau fractures
fix articular segment to shaft
dislocation of the knee joint is
uncommon and due to high energy trauma
why is it uncommon to dislocate the knee joint
- To dislocate the knee four ligaments must be ruptured:
- MCL
- LCL
- ACL
- PCL
which artery is often injured due to dislocation of the knee joint
- Popliteal artery is tethered proximally when it enters the popliteal fossa at the adductor hiatus and distally where it exits the popliteal fossa by passing under the tendinous arch of the soleus muscle
- Popliteal artery is immobile, so if knee joint dislocates there is a high risk of being injured
- It may tear resulting in an obvious haematoma or it may be crushed
- Popliteal artery is immobile, so if knee joint dislocates there is a high risk of being injured
management of knee joint dislocation
Anterior and posterior cruciate ligament injury
Very common
- ACL is weaker than PCL – more commonly injured
Anterior cruciate ligament (ACL)
tears usually occur due to quick deceleration, hyperextension or rotation (e.g. with a sudden change of direction), or due to a blow to the back of a flexed knee.
In an ACL injury, the tibia slides
anteriorly under the femur.
presentation of ACL injury
v
prognosis of ACL injury
- Some patients with low functional demands on the knee function well with a ruptured ACL using musculature to stabilise the joint
- Active people will need surgical reconstruction
posterior cruciate ligament injury
Posterior cruciate ligament (PCL) tears usually occur due to an external force on a flexed knee (a ‘dashboard injury’) or due a fall onto a flexed knee with a plantar-flexed ankle.
In a PCL injury, the tibia slides
posteriorly under the femur.
common cause of a PCL injurty
‘dashboard injury’- road traffic collision
managment of PCL injury
- Conservative management with bracing and rehab
diagnosis of a cruciate injury
They can be tested by the drawer test (for both ACL and PCL tears) and Lachman’s test (ACL only).
treatment of cruciate ligament injury
Treatment can range from RICE (rest, ice, compression and elevation) to surgery to reconstruct the ligament with a section of tendon from elsewhere if needed.
collateral ligament injury cause
Collateral ligament tears are a common sporting injury that occur due to a direct blow to the side of the knee.
- varus and valgus deformity
varus deformity
A varus deformity occurs if the tibial plateau sits medially to where it should be. This is caused by a lateral blow, and results in medial collateral ligament damage.
valgus deformity
A valgus deformity occurs if the tibial plateau site laterally to where it should be, caused by a medial blow to the knee and resulting in lateral collateral ligament injury. .
is varus or valgus more common
Medial collateral ligament tears are more common because a blow to the lateral side of the knee is easier to obtain than a blow to the medial knee.
presentation of collateral ligament injury
This condition presents with pain, stiffness, swelling and instability and pain is increased when either a varus or valgus stress test is performed.
The majority of collateral ligament tears can be treated with
ice, painkillers, bracing and strengthening exercises but occasionally surgery may be required.
Unhappy Triad
the unhappy triad is also known as a ‘blown knee’. It describes a combined injury to the ACL, medial collateral ligament and medial meniscus due to a blow to the lateral knee.
It is a very severe injury and can permanently reduce the function of the knee.
Unhappy triad managment
If mild, RICE and strengthening exercises may be sufficient to treat this condition but often arthroscopic surgery may be required to repair the torn structures (ACL and medial meniscus as MCL usually heals on its own).
Physical therapy is an important part of recovery whether surgery is required or not.
meniscal injury cause
A torn meniscus is one of the most common knee injuries and is often caused by forceful rotation of the knee.
It often occurs in young athletes but can occur in the elderly with little or no trauma because of degenerative changes to the knee.
presentation of meniscal injury
This condition usually presents with: intermittent pain at the joint line, a clicking, catching or locking sensation and reduced movement causing instability.
what is a delayed symptom of a meniscal tear
Swelling occurs as a delayed symptom due to reactive effusion or not at all, as the menisci are largely avascular
- Acute haemarthrosis is therefore rate if present, indicates a tear in the peripheral vascular aspect of the meniscus OR associated injury to the anterior cruciate ligament
- Chronic effusion (increased synovial fluid) can occur due to synovitis (inflammation of the synovial membrane
reactive effusion
- An effusion is an accumulation of fluid inside the knee joint- never normal
- Can be acute (<6 hours after injury) or delayed (>6 hours after injury)
- In an ACL rupture, bleeding often occurs inside the joint- referred top as a hemarthrosis
- Delayed swelling of the knee is usually due to reactive synovitis
- Inflammation of the synovium in response to injury
Acute knee effusions can be divided into:
- Haemarthrosis (blood in the joint). Diagnostically, a haemarthrosis is an ACL rupture until proven otherwise.
- Lipo-haemarthrosis (blood and fat in the joint). A lipo-haemarthrosis is a fracture until proven otherwise as the fat has usually released from the bone marrow
Treatment of a meniscal injury
- Treatment can range from RICE (rest, ice, compression and elevation) and strengthening exercises to surgery (either for repair or to trim meniscus to reduce symptoms).
- Surgical
- Meniscectomy or meniscal rapid
- Conservative management is increasingly recommended
Osgood-schlatters disease (OSD)
is inflammation of the patellar ligament/tendon at its insertion into the tibial tuberosity (apophysis).
who is OSD common in
This condition is common in teenage athletes.
presentation of OSD
It presents with localised pain and swelling and in 20-30% of cases, symptoms are bilateral.
- Intense knee pain during running, jumping, squatting, ascending and descending stairs and during kneeling
treatment of OSD
Treatment is generally rest, ice, elevation and over the counter painkillers, plus exercises to stretch and strengthen the tendon. Typically, symptoms completely resolve with age as the growth plate closes, but it can be difficult to enforce rest in the typical patient, reducing effective healing.
bursas of the knee
bursitis
Bursitis is inflammation of a bursa. Most common bursa to be inflamed:
- Prepatellar bursa
- Infrapatellar bursa
- Pes anserinus bursa
Infra-patellar bursitis is also known as
‘Clergyman’s knee’.
Infra-patellar bursitis- clergmans knee cause
This is inflammation of the infra-patellar bursa (a fluid-filled sac that counters friction at a joint and sits just below the patella) due to repeated micro trauma often caused by upright kneeling (classically in the clergy). Infra-patellar bursitis presents as a painful, erythematous swelling below the knee joint.
infrapateller bursa consists of two bursa
- one which sits superficially between the patella tendon and the second referred to as the deep infrapatellar bursa is sandwiched between the patella tendon and tibia bone
- Bursitis most commonly affects the superficial infrapatellar bursa
trreatment of infrapatellar bursitis “clergmans knee”
usually treated with rest, ice, elevation and over the counter painkillers. However, if this is unsuccessful, and aspiration may be taken from the bursa and tested for infection. If there is an infection present, antibiotics will be prescribed and if not, a steroid injection may be given to reduce the swelling at the affected joint. If the bursitis is severe or keeps returning, the bursa may need to be surgically drained/removed but this is very rare.
prepatellar bursistis also knwon as
housemaids knee
Pre-patellar Bursitis cause
This is inflammation of the pre-patellar bursa (a fluid-filled sac that counters friction at a joint and sits in front of the patella) due to repeated micro trauma or a fall. This condition presents as a painful, erythematous swelling directly over the knee joint. It is called ‘Housemaid’s knee’ because it can occur with repeated kneeling forwards e.g. to scrub a floor by hand.
Pre-patellar bursitis management
presentaton of housemaids knee
Signs
- Knee pain and swelling
- Some erythema overly inflamed bursa
- Difficult to walk due to pain and will not be able to kneel on affected side
suprapatellar bursitis
Supra-patellar bursitis is inflammation of the synovial cavity of the knee joint- knee effusion normally presents too
suprapatellar bursititis is a sign of
significant pathology in the knee joint.
Causes of knee effusion and suprapatellar bursitis include:
Osteoarthritis
Rheumatoid arthritis
Infection (septic arthritis; see below)
Gout and pseudogout
Repetitive microtrauma to the joint (as a result of running on soft or uneven surfaces).
ankle arthritis
- No joint space
- Sclerosis
- Osteophytes
- Cysts
- Usually secondary
- Post traumatic
- Inflammatory
- Primary osteoarthritis- 7%
- Usually secondary
treatment of arthritis
Treatment-fusion
Break and let bone remodel
