Healthcare and Medicine Reference
Figure 21.8 Step-by-step guide: joint (knee) aspiration. (a) Cleaning the
marked knee. (b) Drape the area (a sterile fi eld is of paramount importance
in this procedure). (c) Infi ltration of local anaesthetic. (d) Insertion of cannula
into the joint space. (e) Aspiration of turbid fl uid from knee joint.
NB If aspiration is diffi cult, apply pressure on the medial aspect of
the patella; this displaces fl uid toward the lateral aspect of the patella.
The amount of fl uid aspirated depends upon the aim of
the procedure. Only a couple of millilitres of synovial fl uid
are required for analysis. If, however, you are performing the
procedure for symptomatic relief you may continue aspirating
until the patient is comfortable.
As you enter the joint space you will feel a loss of resis-
tance. At this point you will be able to aspirate joint contents
At this point you have the option of removing the needle from
the cannula and aspirating through it directly using another 2-mL
syringe. This will reduce the risk of iatrogenic trauma to the joint
space lining and cartilage.