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