Before you start
Aspiration indications: diagnose cause of swollen joint; tense effusion symptom relief
Steroid injection indications: osteoarthritis, synovitis, inflammatory arthritis, crystalloid arthropathies, tendinopathy (except achilles/patellar), bursitis, entrapment syndromes
Relative contraindications: overlying cellulitis (IV antibiotics required); coagulopathy (INR >1.4, platelets <50, therapeutic anticoagulant <24 hours, clopidogrel <7days); skin lesion over joint; known bacteraemia; adjacent osteomyelitis; joint prosthesis
Joint sizes
Large = knee, ankle, shoulder
Medium = wrist, elbow
Small = MCP, ICP, sternoclavicular, acromioclavicular
Introduction
- Wash hands, Introduce self, Patients name & DOB, Explain procedure and get consent
- Risks: pain, bleeding/haemarthrosis, infection, cartilage damage, damage to local structures
- Corticosteroid risks: tendon atrophy/rupture, avascular necrosis, skin discoloration, local fat atrophy, soft tissue/pericapsular calcification, osteoporosis
- **Check patients clotting screen, platelet count and if they have been on an therapeutic anticoagulant/clopidogrel**
- Check drug allergies
- Ensure assistant is available
- Examine joint and confirm effusion
Preparation part
- Wash hands and apply apron
- Clean a trolley
- Gather equipment onto bottom of trolley (think through what you need in order)
- Sterile pack
- Cleansing snap-sponge (iodine or alcohol/chlorhexidine) x2
- OPTIONAL: Sterile drape with hole in centre (or 2-3 drapes without holes in)
- 10ml syringe and 2 needles (1 blunt fill 18G drawing-up needle, 1 orange 25G) for local anaesthetic
- Injection/aspiration needle (green 21G if large joint, blue 23G needle if medium joint, orange 25G if small joint)
- Syringe
- 20-50ml syringe if doing aspiration (depending on size of effusion)
- 1-5ml syringe if doing injection (5ml for large joint, 2.5ml for medium joint, 1ml for small joint)
- Extra green 21G needle to draw up steroid if doing aspiration
- Cotton gauze swabs (used whenever needed throughout procedure to dry/clean sterile area)
- Sterile dressing
- Equipment to be kept outside of the sterile field
- 10ml 1% lidocaine (maximum 3mg/kg – note 1ml 1% lidocaine = 10mg)
- Blood culture bottles or 2 white-topped sample collection bottles, and 1 purple EDTA tube if doing aspiration
- 80mg Depo-Medrone (methylprednisolone acetate) in 2ml vial if doing large joint injection
- 40mg Depo-Medrone (methylprednisolone acetate) in 1ml vial if doing medium/small joint injection
- Walk to patient
- Wash hands
- Open sterile pack to form a sterile field on the top of the trolley
- Open packets (without touching the instruments themselves) and drop sterile instruments neatly into the sterile field
- Pick up waste bag from sterile pack without touching anything else and stick to side of trolley
Patient part
Positioning and exposure
- Position patient
- Expose joint and place incontinence pad below
- Examine the surface anatomy of patient’s joint
- Locate insertion point
- Mark insertion point with a skin pen/indentation
Preparation
- Wash hands
- Apply sterile gloves using sterile technique (open pack on a side surface)
- Sterilize area
- Work from middle outwards in one spiral motion (using cleansing snap-sponge)
- Repeat with second cleansing snap-sponge
- Discard used snap-sponges as they are no longer sterile, but note all equipment used after this (including all needles) can be returned to the sterile field after use
- OPTIONAL: Apply the sterile drape over the patient’s body so that the hole is in the correct place to allow access to the insertion site (or apply 2-3 drapes centred around exposed insertion site if no holes)
- Anaesthetise tract
- Ask assistant to snap open lidocaine bottle and hold open upside-down
- Draw up lidocaine using drawing-up needle on 10 ml syringe and expel any air (maximum 7ml if doing injection so the rest can be used with the injection)
- Change to the orange needle and insert at an acute angle to form a single subcutaneous bleb around insertion site in order to anaesthetise the skin
- Now use the same needle to anaesthetise the insertion tract up to the joint capsule
- Always aspirate when advancing the needle (so you know if you enter the joint capsule) and aspirate before injecting lidocaine (to check you are not in a vessel)
Joint aspiration
- With a 20-50ml syringe on the aspiration needle, stretch the skin and insert into the insertion tract
- Aspirate during infiltration
- As soon as fluid enters the syringe, stop advancing the needle and aspirate to fill the syringe/as much as possible
- Withdraw the needle
Joint injection
- Ask assistant to snap open Depo-Medrone bottle and hold this and the lidocaine bottle open upside-down
- Draw up the Depo-Medrone and some lidocaine into the same syringe using a green needle and expel any air
- Large joint: 2ml Depo-Medrone + 3ml lidocaine (in 5ml syringe)
- Medium joint: 1ml Depo-Medrone + 1ml lidocaine (in 2.5ml syringe)
- Small joint: 0.25ml Depo-Medrone + 0.25ml lidocaine (in 1ml syringe)
- Change to the injection needle, stretch the skin and insert into the insertion tract
- Aspirate during infiltration
- When in place, aspirate to ensure you are not in a vessel and slowly expel the contents of the syringe
- Withdraw needle
Finally
Joint specific techniques
Knee
- Suprapatellar approach
- Position patient lying supine with the knee extended
- Identify the midpoint of the superolateral border of the patella
- Insert needle 1cm above and 1cm lateral to this point
- Direct the needle inferomedially and angle slightly posteriorly (at ~ 45Ëš from horizontal plane), between the posterior surface of the patella and the intercondylar femoral notch
Knee aspirate – suprapatellar approach
- Parapatellar approach (preferred aspiration approach)
- Position patient lying supine with the knee extended
- Identify the junction of the upper and middle third of the patella on its medial or lateral border
- Apply pressure to the opposite border of the patella to open the joint space
- Palpate the groove under the patella (~5-10mm laterally) and insert the needle here
- Direct the needle medially and a little inferiorly in the horizontal plane, between the posterior surface of the patella and the intercondylar femoral notch
Knee aspirate – parapatellar approach
- Infrapatellar approach
- Position patient sitting on the side of the bed with knees at 90Ëš over side
- Identify the inferior border of the patella and the patella tendon
- Insert the needle 5mm inferior to the inferior border of the patella, just lateral to the patella tendon
- Direct the needle superomedially and angle slightly posteriorly (at ~ 45Ëš from horizontal), between the posterior surface of the patella and the intercondylar femoral notch
Note: lateral approaches are described above but identical medial approaches may also be used
Shoulder
- Anterior approach (preferred)
- Position the patient in a seated position with their shoulder externally rotated
- Palpate the coracoid from anteriorly
- Insert the needle 1cm lateral to the coracoid (medial to head of humerus)
- Direct the needle posteriorly and angle slightly superolaterally
Shoulder aspirate – anterior approach
- Posterior approach
- From posteriorly, palpate the acromium (posteriorly) and coracoid (anteriorly)
- Insert the needle 1cm inferior to the posterior tip of the acromium
- Direct the needle anteriorly and angle slightly medially towards the coracoid
Wrist
- Position the patients forearm on a stable surface, with their palm facing downwards
- Ask the patient to extend their thumb to identify the extensor pollicis longus tendon, and also locate Lister’s tubercle (bony prominence at distal end of radius)
- Insert the needle distal the Lister’s tubercle and lateral to extensor pollicis longus tendon
- Direct the needle ventrally, perpendicular to the forearm
Wrist aspirate
Elbow
- Position the patients elbow at 90Ëš flexion, rested on a stable surface
- Palpate the olecranon process, the lateral epicondyle and the radial head
- Insert the needle the centre point of this triangle, perpendicular to the skin
Elbow aspirate
Ankle
- Anterolateral approach (preferred)
- Position the patient lying supine with ankle at 90Ëš
- Palpate the space between the lateral malleolus (laterally) and the extensor digitorum longus (medially) in the ankle joint line
- Insert the needle midway between
- Aim the needle posteriorly, perpendicular to the fibular shaft
Ankle aspirate – anterolateral approach
- Anteromedial approach (risks damage to dorsalis pedis and deep peroneal nerves)
- Position the patient lying supine with ankle at 90Ëš
- Palpate the space between the medial malleolus (medially) and the tibialis anterior tendon (laterally) in the ankle joint line (just above the talus)
- Insert the needle midway between
- Aim the needle posteriorly and slightly laterally, perpendicular to the tibial shaft
Note: you can ask patient to dorsiflex foot against resistance to help identify tendons
Metacarpophalangeal joint
- Rest the hand on a stable surface, palm down with the fingers slightly flexed
- Insert the needle dorsally, either medial or lateral to the extensor tendons
MCP joint aspirate
To complete
- Thank patient and cover them
- Bin waste and gloves, dispose of sharps safely in sharps bin, clean trolley and wash hands
- If required, label sample tubes and send to lab:
- MC&S (blood culture bottles or white-top x2) → microbiology
- Crystals (white-top) → cytology
- Cell count (purple EDTA tube) → haematology – if the local hospital haematology laboratory do not do synovial fluid cell counts, the MC&S should be sent in a white-top, so microbiology can do cell count
- Fully document procedure in patients notes
Learn how to interpret the results too…
Synovial fluid result interpretation is covered here!