Ses 3 Msk Knee Disorders Flashcards
Fractures of the femoral shaft, distal femur and
proximal tibia notion
Femoral shaft:
Cause = High energy injuries such as falls from height and car collisions.
Presentation and symptoms = Muscles involved are gluteus medius and minimus causing abduction (greater trochanter)
illiopsoas causing hip flexion (lesser trochanter)
adductor muscles causing varus deformity of distal segment
gastrocnemius causing extension.
There is blood loss of around 1500 ml so may develop hypovolaemic shock.
Treatment = Traction Splint or Surgical fixation
Distal femur
Causes = high energy sporting injury or falling over from standing in elderly.
Symptoms = There is often significant displacement so popliteal artery may be affected.
Tibial Plateau Fractures - usually lateral tibial condyle.
Cause = The usual mechanism is axial (‘top to bottom’) loading with varus or valgus angulation (an abnormal medial or lateral flexion) of the knee.
Symptoms = Articular cartilage damage, Post-traumatic OA
Patella fractures and dislocations/Subluxation notion
Causes = by direct impact injury (e.g. knee against dashboard) or by eccentric contraction of the quadriceps.
Presentation/ symptoms= Is the Extensor Mechanism intact? If not patella that is distal to quadriceps tendon is split. So patient cannot do a Straight Leg Raise.
Haemarthrosis (blood in the joint).
Displaced – Reduce & Fix
Undisplaced – Splint
Beware Bipartite Patella - failure of union of a secondary ossification centre with the main body of the patella.
Dislocation / Subluxation(means still partially articulating )
Causes = internal rotation of femur on flexed knee(eg sudden change of direction in sports).
Trauma - twisting injury or direct blow.
Most likely lateral dislocation
Predispositions are common:
– Weakness of the VMO
– Ligamentous laxity
– Shallow trochlear groove
– Long patellar ligament
– Previous dislocations
Treatment is extend knee and reduce patella. Immobilise for healing.
Meniscal injuries
Cause = Twisting injury in high flexion
Presentation/ symptoms = Localised pain in the joint line
knee locking(loose meniscal fragments becoming trapped between the articular surfaces so cannot fully extend), clicking, catching
swelling(only vascular at peripheries or could be due to synovitis).
Treatment = Menisectomy / Meniscal repair
But it is Degenerative so better to Leave alone & Rehabilitate?
Collateral ligament injuries
Cause = Contact / Direct blow, Varus or valgus angulation.
Presentation/ symptoms = Medial collateral ligament causes valgus rotation.
Lateral collateral – Varus strain - greater instability.
Patient will experience pain and swelling
knee joint may feel unstable and giving way.
Brace & Rehabilitation
Anterior and posterior cruciate ligament injuries
Anterior (ACL)
Non contact -deceleration, hyperextension or rotational injury.
Popping sensation in their knee with immediate swelling, instability-posterior displacement of tibia relative to femur.
Anterolateral Rotatory Instability - medial tibial condyle rotates internally and the lateral tibial condyle subluxes anteriorly.
Spontaneous reduction(goes back into place) of the lateral tibial condyle then occurs with a sudden ‘slip’ when the knee is flexed to 20-40˚.
Posterior (PCL)
Contact - direct force - dashboard injury, Fall onto knee, hyperextension
tibia can be displaced posteriorly on the femur.
bracing and rehabilitation.
Anterior and posterior drawer tests respectively (See video). Lachman’s test can also be used to detect ACL injuries.
Unhappy triad: Medial meniscus, Medial collateral ligament and anterior cruciate ligament injury.
This results from a strong force applied to the lateral aspect of the knee. The medial meniscus is firmly adherent to the medial collateral ligament, which is why it is also injured.
Dislocations of the knee joint
• Uncommon
• High energy trauma
• 3 out of 4 ligaments must be ruptured
• Vascular injury – Popliteal artery tethers - haemotoma or traction injury – Angiography / MRA
• Reduce & Stabilise
Bursitis: Prepatellar bursitis (‘housemaids knee’),
superficial infrapatellar bursitis (‘clergyman’s knee’),
suprapatellar bursitis (knee effusion) and
semimembranosus bursitis (popliteal cyst)
Fluid filled sacks protecting bony prominences
Bursitis - Inflammation (and fibrosis) of a Bursa
Pre-patellar Bursitis
– ‘Housemaids knee’ - inc fluid in this space - repetitive trauma, fall onto the knee, blunt trauma
Infra-patellar Bursitis
– ‘Clergyman’s knee’ - repeated microtrauma caused by activities involving kneeling.
Supra-patellar Bursitis - extension of synovial cavity so
Knee joint effusion. Causes of a knee effusion include:
• Osteoarthritis
• Rheumatoid arthritis
• Infection (septic arthritis)
• Gout
• Repetitive microtrauma to the joint (as a result of running on soft or uneven surfaces).
Semimembranosus Bursitis
– Popliteal (Baker’s) Cyst - If the knee joint is inflamed
and there is an effusion, the fluid can force its way through popliteal fossa into the semimembranosus bursa.
Osgood-Schlatter’s disease
OSD is inflammation of the apophysis (site of insertion) of the patellar ligament into the tibial tuberosity.
Bone growth exceeds the ability of the muscle-tendon unit to stretch sufficiently to maintain previous flexibility leading to increased tension across the apophysis.
Teens playing sport (running and jumping) causes localised pain and swelling.
Resolves when the apophysis fuses.
Septic arthritis
Cause = Septic arthritis is the invasion of the joint space by micro-organisms.
most common pathogen is Staphylococcus aureus.
Risk factors include the extremes of age, diabetes mellitus, rheumatoid arthritis, immunosuppression and intravenous drug abuse.
Prosthetic joints are at risk, either due to intra- operative contamination or to haematogenous spread from a distant infective focus (e.g. during dental surgery). Delayed wound healing, cement used in the joint replacement also inhibits white blood cell and complement function.
Symptoms = damage to articular cartilage or host immune response
Symptom triad is fever, reduced range of motion and pain.
Should be examined for swelling, erythema, calor.
Aspirate joint, culture and microscopy.
Osteoarthritis of the knee
Fluctuating symptoms
Pain precipitated by activities and worse after rest.
Varus, valgus or fixed flexion deformity.
Loss of cartilage - bone on bone so crepitus. Effusion so swelling.
Joint space narrowing
• Osteophytes
• Sclerosis
• Subchondral cysts
Predispositions – Age / Sex / Weight / Post-trauma /
Genetics
Treatment – Strengthening exercises / Analgesia /
Weight loss / Activity modification – Surgery
Swellings around the Knee notion
Swellings around the knee can be:
• Bony e.g. Osgood-Schlatter’s disease
• Soft tissue - Localised e.g. a popliteal artery aneurysm or generalised e.g. lymphoedema.
• Fluid
o Inside the joint = effusion. Acute and delayed.
Acute is heamoarthrosis(ACL rupture) or lipo-haemarthrosis (blood and fat in the joint - fracture so fat from the marrow).
Delayed is reactive synovitis
o Outside the joint = soft tissue haemotoma
VITAMIN C and D for swelling
V = vascular - haemoarthrosis due to ACL tear
I = inflammation- bursitis
T = trauma - meniscal tear
A = autoimmune- RA
M = metabolic - gout
I = iatrogenic - prosthetic joint leading to septic arthritis
N = neoplasia
D = degenerative - OA
C = congenital
