Joint aspirations and injections
Attention
- Do not do unless you have been trained. Medical consult prior to procedure
- Most common joints to be injected/aspirated are knees, shoulders
- Principles for joint injection and aspiration the same
- Be aware of risk of introducing infection — always use aseptic technique
- Before aspirating for diagnostic reasons — see Joint fluid analysis
- If aspirating for healing (therapeutic) reasons — remove most of the fluid
- Local anaesthetic not always needed. Depends on size of needle used
- Always put needle in parallel to joint surfaces to prevent damage to cartilage
- Use ultrasound guidance for shoulder injection if available
Note: Leave a bit of air in preloaded syringe. Air can easily be injected into joint but not tissue (strong resistance), helps you know if you are in joint
Circulation and sensation — when finished always check hands/feet (peripheries) for colour, warmth, sensation, movement, swelling, capillary refill, peripheral pulses — F 10.1, to make sure no damage to nerves, arteries or veins.
Syringes and needle sizes
- Needle size depends on
- Diagnostic or healing (therapeutic) aspiration
- How much fluid and how thick
- Size of joint
- Always use smallest needle size possible
- For aspiration usually 21G
- For injection usually 23G
- Needle length
- Long — 32mm for shoulders or knees, 38mm for obese patients
- Needle and syringe size for aspiration of toe/finger — 25G needle and 3mL syringe
- Aspiration of knee/shoulder
- 21G OR 18G needle/cannula if you expect thick or bloody fluid
- 5mL syringe for diagnostic
- 10–20mL syringe for healing (therapeutic) aspiration
Do not
- Do not do joint aspirations if
- Bacteraemia present
- Skin infection or severe dermatitis over joint
- Joint too difficult to reach
- Severe lack of blood clotting (coagulopathy)
- Gout in big toe (classic first metatarsophalangeal gout), very painful, not needed for diagnosis
- Do not do steroid injection if
- Bacteraemia present
- Infectious arthritis
- Close to bone infection (osteomyelitis)
- Person having joint replacement surgery in less than a week
- Bleeding into joint (haemarthrosis)
Indications (reasons) for joint aspiration
- Therapeutic (to help with healing)
- To relieve symptoms (pain, swelling)
- To help stop damage to joint caused by infection
- Diagnostic
- To improve joint movement so swollen joint can be fully examined
- To find reason for unexplained fluid build-up in joint
Types of effusions
Bloody effusions
- Traumatic — most common
- Bloody aspirate indicates soft tissue or bony injury
- Fat globules in bloody aspirate indicate joint fracture
- Usually contain streaks of clotted blood
- Non-traumatic
- Include haemophilia, anticoagulant therapy, malignant/benign tumours
- Fluid is evenly bloody
- May be caused by traumatic tap during joint aspiration — usually contains streaks and fresher looking blood
- Don't need to send bloody aspirate to pathology unless you suspect septic arthritis, crystal arthropathy, malignant tumour
- Non-traumatic effusions are usually non-bloody. Send aspirate to pathology for diagnosis
- Single inflamed joint could be septic arthritis. Very damaging
- 20% of people with septic arthritis don’t have a fever
- 20% of cases of septic arthritis involve more than one joint
What you need
- Blueys
- Sterile dressing pack
- Chlorhexidine 5% in 70% alcohol solution or povidone-iodine antiseptic solution
- Syringes and needles
- Sterile needle holder or haemostat clamp (to keep needle still when changing syringes)
- Small sticking plaster
- Compression bandage
May need
- Large pillow
- 3mL syringe preloaded with local anaesthetic and/or steroid for injection
- Yellow cap sterile specimen container for aspirate
- Crutches
Knee injection/aspiration — medial and superolateral approach
Attention
- Usually
- Medial approach for injections and small (diagnostic) aspirations
- Superolateral approach for large (healing/diagnostic) aspirations
- Use method you are most comfortable with
What you do
Medial approach
- Lie person on back with knee bent 45–90° over bluey-covered large pillow
- Find site for aspiration/injection — Figure 10.83
- Mark injection site by making indentation with tip of syringe
- Lay out dressing pack and equipment
- Wash hands and put on sterile gloves
- Disinfect site and drape with sterile towels
- Put needle
- Into triangular space made by edge of femoral condyle, tibial plateau (make sure you can palpate edge of tibial plateau) and patellar tendon, 1cm medial to patellar tendon — Figure 10.83
- Behind patella, aiming for femoral notch. Direct inward and slightly backward toward person’s thigh for 2–3cm
Figure 10.83
Superolateral approach
- Lie person on back with leg straight
- Put in needle 1–2cm above (superior) and 1–2cm to outside (lateral) of upper outer aspect of patella at 45° angle, and at 45° to skin surface — Figure 10.84
Figure 10.84
For both medial and superolateral approaches
- If aspirating
- Connect aspirating needle and syringe
- Put spare hand (or have helper put their hand) on thigh above knee, press distally to milk effusion into joint. Take care to keep area sterile
- Put in needle, pushing in slowly while aspirating until you see fluid, then aspirate
- Don’t aspirate while needle being withdrawn through the skin. Can contaminate aspirate
- If injecting
- Inject skin and deeper tissues at needle insertion site with local anaesthetic
- Use sterile needle holder/forceps (with non-dominant hand in pencil grip) to hold needle in joint, disconnect syringe, attach steroid/lidocaine (lignocaine) syringe
- Put needle gently into centre of insertion site, push in slowly while aspirating until you see fluid or hit bone. If bone hit — pull back slightly
- Inject
- If aspirating and injecting
- Do aspiration
- Use sterile needle holder/forceps (with non-dominant hand in pencil grip) to hold needle in joint, disconnect aspiration syringe, attach steroid/lidocaine (lignocaine) syringe
- Inject
Now
- Take out needle, put firm pressure over site with thumb to stop any bleeding
- Put on sticking-plaster dressing
- If blood aspirated — put on firm bandage, arrange crutches
- Put aspirate into specimen jar, store and transport under refrigeration
- Check circulation and sensation
Shoulder joint injection/aspiration — lateral approach
What you do
- Sit person comfortably on chair or couch facing you, arm hanging loosely by side, palm turned forward
- To find site
- Gently turn shoulder around from inside to outside to feel head of humerus
- Find groove between head of humerus and glenoid rim
- Needle entry site is in groove 1cm below and just lateral to coracoid process — Figure 10.85
Figure 10.85
- Mark site by indenting skin with tip of syringe
- Lay out dressing pack and equipment
- Wash hands and put on sterile gloves
- Clean front of shoulder
- Inject local anaesthetic into skin, if using
- Connect syringe to needle. If injecting only — remember to start procedure with smaller needle
- Put needle gently into shoulder at identified site. If you hit bone — pull back slightly
- Aspirate fluid
- Use sterile needle holder/forceps (with non-dominant hand in pencil grip) to hold needle in joint, disconnect aspiration syringe, attach steroid/lidocaine (lignocaine) syringe
- Inject
- Take out needle, put firm pressure over site with thumb to stop any bleeding
- Put on sticking-plaster dressing
- Put aspirate in specimen jar, store and transport under refrigeration
- Check circulation and sensation
Shoulder joint — subacromial bursa injection
Attention
- Do not inject into tendon. If needle enters tendon (gritty resistance) — pull out straight away
- Aim to inject into soft tissue that lines non-cartilaginous surfaces (subacromial bursa)
- If injection in right place — pain will be quickly relieved
What you need
- Sterile dressing pack
- Chlorhexidine 5% in 70% alcohol solution or povidone-iodine antiseptic solution
- Local anaesthetic and equipment (if using)
- 3mL syringe preloaded with lidocaine (lignocaine) 1% and 1mL of steroid for injection
- Long 23G or 25G needle
- Small sticking-plaster dressing
What you do
- Ask person to put affected arm behind their back, with backs of fingers touching far waistline
- Palpate acromial margin laterally or posterolaterally
- Injection is below acromial margin, laterally, directed upward under acromion — aim for coracoid process
- Mark injection site by indenting with end of syringe
- Lay out dressing pack and equipment
- Wash hands and put on sterile gloves
- Clean site and drape with sterile towels
- Inject local anaesthetic into skin, if using
- Connect preloaded syringe and needle
- Guide needle tip into site, beneath acromion, angled slightly upward and parallel to acromial under surface — Figure 10.86
Figure 10.86
- Inject air you have left in syringe to see if you are in joint. If no resistance felt — inject lidocaine (lignocaine) and steroid
- Take out needle, put firm pressure over site with thumb to stop any bleeding
- Put on sticking-plaster dressing
- Check circulation and sensation
Steroid injection
- Steroid injections give pain relief
- Adding lidocaine (lignocaine) to steroid injection
- Relieves pain at target site
- Helps you work out if medicine has reached its target
- Allows area to be re-examined while joint under anaesthesia
- Helps to tell difference between local and referred pain
- Gives volume to injection fluid
- Distributes corticosteroid in large joints
Lidocaine (lignocaine) concentration
- More concentrated (eg 2%) for small joints needing smaller volume
- Less concentrated (eg 1%) for large joints needing larger volume
Attention
- Infection after injection rare. Prevented by making sure person knows how to keep site clean
- Post-injection flare (2–5%). Painful condition, starts 6–12 hours after injection, lasts 2–3 days. Easily confused with infection. Prevented by
- Avoiding weight-bearing and vigorous activity with injected joint for 48 hours post-injection
- Applying ice
- NSAIDs — if no contraindications — Pain management (acute)
- Steroid dose
- Reduce dose for young people, the elderly, those in poor health
- Be careful with short-acting steroids in people with diabetes. Risk of increased blood glucose levels for up to 3 weeks after injection
What you need
- See above What you need
AND
- 1mL betamethasone mixed with 3–5mL of lidocaine (lignocaine) 1%
- OR 1mL methylprednisolone mixed with 3–5mL of lidocaine (lignocaine) 1%
- 3mL syringe preloaded with lidocaine (lignocaine) and steroid
- Small joints (eg wrists, ankle) — consider stronger steroids in smaller volumes
Joint fluid analysis
- Send non-bloody fluid to pathology for cell count, gram stain, bacterial culture and if needed, special tests such as crystals, fluid-protein, fluid-glucose and fluid-LD levels
- Do cultures on all synovial fluids. Bacterial infections can look like/be present with joint disease
Collection
- Need a minimum of 2mL aspirate in sterile yellow container for gram stain, culture, WBC, crystals
- For diagnosis
- If enough fluid, put 1–2.5mL in EDTA tube (purple lid) — gives more accurate analysis of WBC. Important if delay in transport
- If septic arthritis suspected and enough joint fluid — put 2.5mL in blood culture bottle (aseptic technique)
Transport
- Best within 4 hours, but no later than 48 hours. Refrigerate if delay
- Use blood culture bottle
Results
Joint fluid analysis will fall into one of 3 categories — Table 10.1
- Non-inflammatory
- Degenerative (eg osteoarthritis, overuse syndrome)
- Trauma, if no blood in fluid
- Septic (eg infective mono-arthritis)
- Non-gonococcal bacterial arthritis
- Gonococcal bacterial arthritis
- Inflammatory
- Acute crystal arthropathy (eg gout, pseudogout)
- Any type of arthritis
Synovial fluid findings
Table 10.1 Microscopic findings