Healthcare and Medicine Reference
In-Depth Information
Contraindications
Overlying cellulitis.
superiorly - superior to the patella it is continuous with the
suprapatellar bursa - this bursa continues 5 cm superior to the
patella normally
inferiorly - attachments to the tibial condyles and both
Coagulopathy.
Thrombocytopenia.
menisci.
Prosthetic joint.
Brief anatomy of the knee joint
The knee joint is the largest and most commonly aspirated joint.
A basic understanding of its anatomy is essential to perform a safe
aspiration.
It is a synovial hinge joint with a wide range of movement. This
range of movement is at the sacrifi ce of stability. The knee therefore
has ligaments and menisci which act to improve the stability of the
joint.
The main articulation is formed between the the condyles of
the femur and tibia. This articulation is deepened by two c-shaped
fi brocartilageous structures, menisci, which also absorb shock
transmitted through the joint.
Four ligaments stabilise the knee joint.
Anterior cruciate ligament (ACL), which prevents anterior
Step-by-step guide: knee aspiration lateral
approach
Give a full explanation to the patient in simple terms and
ensure they consent to the procedure.
Set up your trolley (Box 21.2 and Figure 21.7).
Prepare your trolley as a sterile fi eld. Wear a plastic
disposable apron and non-sterile gloves, and take alcohol
hand rub with you.
1
Place the patient relaxed in the supine position on a couch with a
pillow under the knee, creating slight fl exion of the joint.
Mark with a pen or surgical marker the point 1 cm superior and
2
1 cm lateral to the upper border of the patella.
Adopt universal precautions, set a sterile fi eld, prepare the skin
displacement of the tibia on the femur.
Posterior cruciate ligament (PCL), which prevents posterior
3
and drape the area (Figure 21.8a,b).
Anaesthetise the area around your aspiration site (Figure 21.8c).
displacement of the tibia on the femur.
Medial and lateral collateral ligaments, which act to stabilise
4
5
With the brown cannula attached to a 20-mL syringe, advance
medial and lateral aspects of the knee joint, preventing separa-
tion of the femur from tibia (e.g. a blow to the lateral aspect of
the knee joint will potentially strain the medial collateral
ligament).
through the previously marked spot at a direction 45° inferiorly
and 45° down into the knee joint, attempting gentle aspiration
as you advance.
Joint capsule
The attachments of the joint capsule are complex but it is
important to be aware of its anterior and lateral boundaries, as
this will guide your placement of the needle during aspiration
(Figure 21.6). The attachments are:
medially - articular margin of the femur
Box 21.2 Equipment for joint aspiration
Sterile pack, including drapes, a gallipot and gauze
Sterile gloves
Local anaesthetic
28G needle
5-mL syringe
laterally - the groove of the popliteus tendon
Brown intravenous cannula (14G venfl on)
20-mL syringe
Iodine-based solution for skin preparation (unless allergic)
A minimum of two universal containers
Femur
Joint
Capsule effusion
Tibia
Figure 21.6 Knee joint.
Figure 21.7 Equipment required for joint aspiration.
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