knee pathology
similar to the elbow, assess the knee as a group of compartments:
- suprapatella
- prepatella
- infrapatella
- medial knee joint
- lateral knee joint
- posterior knee joint
it is important to recognise the strengths and weaknesses of ultrasound. within the knee, ultrasound cannot exclude meniscal or cruciate pathology.
suprapatella
- primarily pathology is of the quadriceps tendon and suprapatella bursa (which is an extension of the joint capsule).
suprapatella bursa / recess
ultrasound image- a panoramic view of an extensive, partial rectus femoris tear. the disrupted fibres and fluid are seen.
ultrasound image- a traumatic, large complex effusion distending the suprapatella bursa.
transverse ultrasound view of a complex suprapatella bursal effusion.
this may be a haemarthrosis or pyarthrosis depending on clinical presentation.
ultrasound image- a traumatic, large complex effusion distending the suprapatella bursa.
quadriceps tendon
ultrasound image- a panoramic view of an extensive, partial rectus femoris tear. the disrupted fibres and fluid are seen.
prepatella
rectus femoris tear
ultrasound image- the diffuse fluid collection seen in prepatella bursitis.
infrapatella
the infrapatella tendon, or patella ligament from the apex of the patella to the tibial tuberosity.
ultrasound image- focal hypoechoic change centrally within the infrapatella tendon at it’s origin on the apex of the patella.
ultrasound image- transverse view of the same focal tendinosis.
ultrasound image- acute infrapatella tendonosis: thickening & hyperaemia proximal to the inferior insertion.
ultrasound image- longitudinal thickened patella tendon.
oedema of the underlying hoffa’s fat pad and overlying subcutaneous oedema.
bifid infrapatella tendon. the central portion has been harvested for cruciate repair as evident on the following ap knee x-ray.
anchor screws for the anterior cruciate ligament repair.
osgood schlatters disease
ultrasound image- osgood schlatters disease involves inflammation of the patella tendon insertion to the tibial tubercle apophysis in adolescents.
ultrasound image- compare normal left to the abnormal right. the calcification and soft tissue thickening is pathognomonic of osgood schlatters.
pes anserinus
ultrasound image- thickened left pes anserinus insertion.
ultrasound image- an acute on chronic tear of the pes anserine insertion in a football (soccer) player.
medial collateral ligament (mcl)
ultrasound image- hyperaemia of the medial collateral ligament at it’s femoral origin suggesting an acute process.
ultrasound image- markedly degenerated medial meniscus. note the punctate calcifications.
ultrasound image- medial collateral ligament (mcl): hypoechoic thickening of the superior, superficial component of the mcl.
lateral knee joint
ultrasound image- degenerative lateral knee joint.
-this image shows:
- marked boney irregularity
- slight joint fluid
- markedly irregular meniscal margins
- slight laxity and loss of fibrillar pattern of the lcl suggestive of a tear.
posterior knee joint
bakers cyst – the semimembranosus gastrocnemial bursa.
ultrasound image- the semimembranosus-gastrocnemial bursa (baker’s cyst): by remembering the name, the anatomical position can be determined to ensure incorrect diagnoses are avoided (for example a popliteal fluid collection associated with a hamstring tear).
ultrasound image- a baker’s cyst is subject to: •haemorrhage (from the knee joint) •septations (when chronic) •rupture (causing medial upper calf pain +/- swelling)
ultrasound image- complex debris within a bakers cyst.
ultrasound image- loose calcifications within a bakers cyst.
popliteal artery.
ultrasound image- a popliteal artery aneurysm graft.
ultrasound image- split screen transverse view of a popliteal aneurysm and graft.
popliteal veins
ultrasound image- occlusive popliteal vein thrombuss (dvt).
dvt must be excluded as a cause for popliteal fossa pain.
ultrasound image- short saphenous vein thrombosis ls.
ultrasound image- thrombosus of the short saphenous vein (ssv).
always exclude deep or superficial thrombosis as a source of posterior knee pain.
hamstrings and gastrocnemius tendons
ultrasound image- partial tear of the semimembranosus tendon insertion. the tendon has a diffuse insertion involving the meniscus.
ultrasound image- partial tear of the semimembranosus tendon insertion. the tendon has a diffuse insertion involving the meniscus.
ultrasound image- a large area of calcification in the lateral gastrocnemius insertion. note the lack of shadowing from ‘soft’ calcification (hydroxyapatite).
plantaris tendon rupture
the plantaris muscle originates from the posterior lateral femoral condyle next to the head of the lateral gastrocnemius muscle.
it lies between the medial gastrocnemius muscle belly and the soleus muscles. it travels obliquely in the calf. the thin tendon inserts into the achilles tendon.
usually a patient will complain that they felt a snap or a feeling that someone kicked them in the back of leg. there can be bruising around the ankle.
ultrasound image- plantaris tendon rupture seen coursing below the medial gastrocnemius muscle belly.