Chapter 39- Injured Knee And Patella Flashcards
What is the differential for painful knee and no other findings on examination
- referred from hip/ spine
- painful patellar syndrome (will have tenderness on underside of patella)
Differentials for pain on the anterior knee?
Patella: acute: fracture; chronic: chondromalacia
Extensor mechanism: acute: rupture
Chronic: tendonitis
Differentials for blood cause swelling of the knee joint
Swelling is immediate (hours)
- haemarthrosis: confined to synovial space - 70 percent are due to ACL rupture
- meniscal tear or collateral ligament injury
- Intra articular fracture
Differentials for synovial fluid causing swelling of the knee
Occurs in days rather than hours
- meniscal pathology
- joint instability (ligament injury)
- articular pathology
- synovitis
Differentials ‘giving way’ of the knee joint?
- ligamentous laxity (ACL)
- loose body
- meniscal tear
- articular pathology
What does locking of the knee refer to?
Inability to extend the joint
What is the cause of locking of the knee?
Meniscal tear
What is anatomical valgus position of the legs
5 degrees in males and 7 degrees in females
Symptoms of the ACL Injury (at initial injury)
- acute episode, usually rotational stress, during sporting activities
- may have heard or felt a pop or snap sensation
- immediate swelling
- could not continue activities
- pain: variable and sometimes may be mild
- acute symptoms settle in +- 2 weeks
Symptoms of ACL tear (untreated or chronic)
- present with giving way on rotational activities especially
- intermittent swelling with episodes of giving way
- no locking experienced unless a meniscus is torn as well
Findings on examination of an ACL tear
Effusion
Muscle wasting if chronic
Lachman test positive
Pivot shift positive
What is a possible X-ray finding of ACL tear
Avulsion of bony attachment of ACL or ITB
Treatment of ACL Tear in high level athlete
ACL reconstruction: refer to specialist
Rehabilitation: thigh muscle, hamstring in particular, rehab for propriception retraining
Treatment of ACL Low demand individual
- rehab thigh muscles, especially hamstrings
- brace
- reconstruction of ACL is giving way and swelling is the problem
Typical history for collateral ligament tear ( acute)
- varus or valgus stress injury
- pain on medial or lat side
- localized swelling
If persistant pain or instability is associated with the collateral ligament tear what are the likely associated conditions?
- persistant pain: meniscal tear, articular cartilage damage or bone bruise
- instability: associated PCL or ACL injury
Treatment of collateral ligament tear?
- supportive: Robert jones or knee immobilizer
- rehab: quads and hams
Gradual return to activity as discomfort and swelling subsides
How may a chronic PCL tear present (history)
- may present with anterior knee pain months after injury or medial compartment OA years later
- posterior pain: associated postero-lateral capsule tear, meniscal tear or bone bruise
- classic instability rare
Examination findings for PCL
- Minimal if any swelling in isolated history
- Posterior subluxation of the tibia on the femur (post sag sign, tibial step off sign)
Describe the PCL brace
Extension with thick foam pad behind calf muscle
Treatment of PCL tear in high demand individuals
Refer for repair/ reconstruction
Treatment of PCL tears in low demand individuals
Brace in extension with PCL brace for 2-3 weeks
Rehab focused on quads mainly
In a knee dislocation, which other structures should be examined for injury?
- common perineal nerve and popliteal artery
Treatment of knee dislocation
- all knee dislocations must be reduced as soon as possible and an angiogram performed if possible
- vascular injury present: vascular repair, repair accessible tear of the posterior capsule, stabilize the knee with exoskeleton, address remaining instability at a later stage
- no vascular injury: primary if status of tissue permit (i.e. If minimal swelling). If swollen, allow to settle and then address disrupted ligaments. Stabilize with POP cast or exoskeleton
What is the mechanism of injury in a meniscal tear
Tears occur with rotation of the knee in a flexed position
Symptoms of meniscal tear
- pain: posterio-medial/ postero- lateral corners
- locked knee
- intermittent swelling
- flexion deformity
- giving way with low energy activity
- experience clunk or feel something move in the knee
Examination findings for meniscal tear
- tender- medial or lateral joint line
- swelling - effusion
- flex deformity
- muscle wasting if >2 weeks
- mcmurray and steinman positive
Treatment of meniscal tear
- endoscopic repair or partial menisectomy
- Rehab: quads and hams
- crepe or tubigrip support
What types of loose bodies are found in the knee and where do they originate from
- Chondral or osteochondral
- originate from injury to articular cartilage or osteochondritis dissecans fragment
Symptoms of Loose bodies in the knee
- patients can locate it if mobile
- giving way
- locking sporadically
Treatment of loose bodies in the knee
Remove
Replace intra articular defect if osteochondritis dissecans
Causes of extensor mechanism rupture in the knee
- quadriceps tendon: rupture in the elderly
- patellar fracture
- patellar tendon rupture in athletes
Describe quadriceps lag
Patient can passively extend the knee but cannot maintain active extension
Cause and treatment of popliteus tendon rupture
- sharp external rotation of the tibia on the femur may rupture or avulse the popliteus tendon, also seen with LCL injury
- treatment is symptomatic and supportive
What injury is gastrocnemius rupture associated with?
Seen in association with severe lateral ligament disruption
What is the cause of iliotibial band tendinitis? what is the treatment?
- Caused by the ITB passing over the lateral femoral epicondyle during repetitive flexed knee activity
- Treatment is LA and steroid, divide ITB under LA
Treatment of pes anserinus bursitis or tendinitis
Local anaesthetic and steroid- modify activity
Name and describe the types of patellar fractures
- Linear: Due to explosion contraction of the quads, such as jumping down from a height
- Stellate or comminuted fracture: caused by direct blow
Clinical presentation of patellar fracture
- History of a fall/ jump from a height, or direct trauma
- Swollen knee with bruising
- Palapable gap in patella with separation of the fragments
- Unable to elevate leg with knee fully extended
- Movement limited by pain in the acute stage, usually in full flexion in chronic injury with an extensor lag
What are the parameters to define a displaced/undisplaced patellar fracture
Undisplaced: <2mm separation or step
Displaced: >2 mm separation or step
Treatment of undisplaced patellar fractures
-POP cylinder or extension knee brace for 4-6 weeks then active flexion and extension exercises
Treatment of displaced patellar fractures
- Mid-patella: open reduction and internal fixation (tension band wiring) and POP cast in extension for 6 weeks
- Proximal or distal pole: Excise small fragment and repair tendon and POP cast for 6 weeks
- Longitudinal: interfragmentary screw fixation
If irreducible/ irreparable or cartilage too badly damaged –patellectomy
Name a patellar stabilizer that is commonly torn, causing lateral dislocation of the patellar
-Medial Patello-femoral ligament
Causes of patellar dislocation
- Congenital
- Acquired: direct blow forcing it out of position, indirect force: Strong quadriceps contraction with low leg in external rotation (jumping)
Examination findings of patellar dislocation
-Acute: knee held flexed and medial femoral condyle is prominent
Look for
-Overall leg alignment (usually valgus and anteversion of femoral neck with squinting patellae)
-Quadriceps mechanism alignment (Q angle)
-Ligamentous laxity
-Size and position of the patellar
What is the skyline view used to view in a patellar dislocation
-Identify bony avulsion from medial side or an osteochondral injury to the crest of the patella
Treatment of patellar dislocation
Acute:
- Analgesia and and extension to reduce the dislocation
- If significant force: arthroscopy to look for chondral or osteochondral injury
- Repair of retinacular tear in young, active individuals
- immobilise with POP cast in 10-15 degrees flexion
- Rehab of quads
Chronic or recurrent:
- Refer to specialist
- Reconstruction of the medial patello-femoral ligament is recommended
- Rehab of quads
