Disorders of the knee Flashcards
Femoral shaft fractures
High velocity trauma but in elderly can be falling from standing position
How fragments of femoral shaft fractures look
Proximal fragment = abducted due to pull of glut max and med
Distal fragment = adducted due to action of adductor muscles
Tense swollen thigh
Major risks of femoral shaft fractures
Blood loss (in open fractures double that in closed) and hypovolaemic shock
Treatment of femoral shaft fracture
Surgical fixation
Distal femoral fracture
Youth = high energy sport injury Elderly = osteoporotic FFSP
Vascular effect of distal femoral fracture
Popliteal artery involved if significant displacement
Tibial plateau fractures
Diagonal fracture of the condyle of the tibia from high energy injuries, articular cartilage always damaged and end up w post traumatic osteoarthritis
Patellar fractures
Direct impact injury or eccentric contraction of quads
Treatment of patellar fracture
Displaced = reduction and surgical fixation Undisplaced = splinting and crutches
Test of patellar fracture
Fracture completely splits patella distal to insertion of quad tendon = patient can’t do straight leg raise
Normal anatomical variant of patella
Bipartite = failure of union of secondary ossification centre
Patella dislocation
Normally laterally and by trauma - internal rotation of femur on planted foot whilst flexing knee
Predisposition of patellar dislocation
- Lax ligaments
- Weak quads, esp VMO
- Shallow patellofemoral groove
- Long patellar ligament
- Previous dislocations
Treatment of patellar dislocation
Manually reducing patella
Meniscal injuries
Tear in the meniscus due to sudden twisting of knee when flexed
Patient description of meniscal tear and signs
- Intermittent pain localised to joint line
- Knee clicking/catching/locking
- Joint line tenderness
- Restricted motion - pain or swelling
Treatment of meniscal tear
Surgically by removal or repair.
Collateral ligament injury
Acute varus or valgus angulation of knee
The unhappy triad
Injury to:
- ACL
- MCL
- Medial meniscus
Anterior and posterior cruciate ligament injury
ACL weaker than PCL so more commonly injured - changing direction in sport = quick deceleration then hyperextension or rotation
Patient description of ACL injury
Could feel it pop and then it immediately swelled, also felt like it was giving way
Treatment of ACL injury
- Low functional knee demands = ruptured ACL and joint stabilised by musculature
- Sportsmen and active = surgical reconstruction
Common mechanism of PCL injury
Dashboard injury - flexed knee and then large force
Knee joint dislocation
Uncommon and always from high energy trauma - need 3/4 ligaments ruptured
- MCL
- ACL
- LCL
- PCL
Associated artery injury in knee joint dislocation
Popliteal artery passes through political fossa
- Haematoma
- Artery crushed = thrombotic occlusion
Treatment of knee dislocation
Reduction of knee joint
Swellings around the knee
- Bony = Osgood-Schlatter’s disease
- Soft tissue - localised or generalised
- Fluid - inside the joint = effusion, outside the joint
Knee effusions
Accumulation of fluid in the knee joint
- Haemarthrosis - blood in joint e.g. ACL rupture
- Lipo-haemarthrosis - blood and fat in joint
Bursitis of the knee
Inflam of a bursa
Pre-patellar bursa
Knee pain and swelling, repetitive trauma to the bursa = Housemaid’s knee
Infrapatellar bursitis
Repeated micro trauma when upright kneeling = Clergyman’s knee
Suprapatellar bursitis
Is extension of synovial cavity = fluid there
Causes:
- OA
- RA
- Infection
- Gout
- Repetitive microtrauma as a result of running on soft/uneven surface
Semimembranous bursitis
Swelling in the popliteal fossa
Popliteal cyst or baker’s cyst
Osgood-Schlatter’s disease
Inflammation of site of insertion of patellar ligament into tibial tuberosity
Localised pain and swell
Patients - intense knee pain when active
Treatment - rest and ice
OA of knee
Knee pain that comes and goes when bending, kneeling etc, morning stiffness and swelling
Varus or Valgus deformity of knee joint
Crepitus
Buckling knee
Varus
Away from midline
Valgus
Towards midline
Septic arthritis
Invasion of joint space by micro-organisms, knee most common joint affected
Staph aureus most common
Damage to articular cartilage
Risk factors of septic arthritis
- Extremes of age
- DM
- RA
- Immunosuppression
- IV drug use
- Prosthetic joints - infection years can be after initial operation
Symptoms and signs of septic arthritis
- Fever
- Pain
- Reduced range of motion
- Erythema
- Swelling
- Warmth
- Tenderness
- Limitation of active and passive range of motion
Investigations of septic arthritis
Aspiration of joint and aspirate sent for urgent microscopy, culture and sensitivities
Outcome of septic arthritis
High morbidity and if survive often decreased range of motion and chronic pain
