Lidocaine with epinephrine, which comes in ampoules or vials clearly marked in red, should not be used because of risk of ischaemic necrosis in appendages (page 16). Because of its potential half life of 8 hours or more, we do not recommend the routine use of Marcain but occasionally it can be used when a longer anaesthetic effect is needed. Some practitioners like to mix short- and long-acting anaesthetics to gain both the immediate diagnostic effect and the longer therapeutic effect.

Dosages

The corticosteroid doses suggested are what we use for the average-sized adult and are governed by the individual patient’s age, size, general health and clinical history. These are guidelines only and none are ‘cast in stone’; it is up to the clinician to decide on variants depending on individual preference and patient presentation. At all times, the minimum effective dose should be given; this will help prevent the appearance of adverse side effects such as facial flushing, intermenstrual bleeding, hyperglycaemia, skin atrophy and depigmentation.

It is important to keep within the recommended maximum doses of local anaesthetic in order to avoid toxicity. The safe maximum doses we suggest are given in Table 2.3. These doses are half the maximum published in pharmacological texts, so are well within safety limits (BNF).

Table 2.3 Local anaesthetics: suggested maximum doses

In practice, this translates to the following:

• 2% lidocaine up to a maximum volume of 5 ml

• 1% lidocaine up to a maximum volume of 10 ml

• dilute 1% with normal saline (0.9%) for volumes larger than 5 ml.

Volumes

Joints and bursae appear to respond best when sufficient volume of fluid to bathe the inflamed internal surfaces is introduced. Possibly the slight distension ‘splints’ the structure, or maybe it breaks down or stretches out adhesions. In a small patient the amounts are decreased and in a large patient they may be increased. Greater volume can be obtained by using normal saline, and especially in the case of the knee joint where the synovial folds encompass a large total area, greater volume is always recommended in order to bathe the entire inflamed surface.

The volumes suggested in Table 2.3 are well within safety limits and will not cause the joint capsule to rupture; for instance it is not unusual to aspirate over 100 ml of blood from an injured knee joint. In any case, the back pressure created by too large a volume would blow the syringe off the fine needle recommended, long before the capsule was compromised (Table 2.4).

Table 2.4 Joint injections: suggested average doses and total volumes

Joint	Dose	Volume
Shoulder	40 mg	5 ml
Elbow	30 mg	4 ml
Wrist	20 mg	2 ml
Thumb	10 mg	1 ml
Fingers	5 mg	0.5 ml
Hip	40 mg	5 ml
Knee	40 mg	5 to 10 ml
Ankle	30 mg	4 ml
Foot	20 mg	2 ml
Toes	10 mg	1 ml

Conversely tendons should have small volumes injected. This avoids painful distension of the structure and minimizes risk of rupture. An average ‘recipe’ for tendons is given in Table 2.5.

Table 2.5 Tendon injections: suggested average doses and volumes

• Small tendons: 10 mg of steroid plus local in a total volume of 1 ml

• Large tendons: 20 mg of steroid plus local in a total volume of 2 ml

Anatomy

This section gives tips for easy ways to localize and imagine size of anatomical structures, based on functional and surface anatomy. Finger sizes refer to the patient’s fingers, not the clinician’s.

Technique

We describe a logical sequence for administration of the solution, and ways of performing a safe and relatively painless injection (Table 2.6).

Table 2.6 Aseptic technique

Wet hands carry more risk of infection so hands must be well dried before injecting – see the technique recommended by the World Health Organization.^2,⁴^–⁷ Gloves are mandatory in some countries; we recommended wearing gloves when aspirating, but they do not need to be sterile.⁸

Injections should not be painful. Skin is very sensitive, especially on the flexor surfaces of the body, and bone is equally so. Muscles, tendons and ligaments are less sensitive and cartilage virtually insensitive. Pain caused at the time of the injection is invariably the result of poor technique – ‘hitting’ bone with the needle instead of ‘caressing’ it. After-pain can be caused by a traumatic periostitis because of damaging bone with the needle, or possibly by flare caused by the type of steroid used. Success does not depend on a painful flare after the infiltration.

Alternative approaches

There is usually more than one way to give an injection. We have selected approaches which we find to be the safest, easiest for the injector and least uncomfortable for the patient. Here we describe equally effective or alternative ways where appropriate.

Aftercare

Most injection studies show that injections give demonstrable relief in the short term but there is not much difference from other treatments or no treatment at all in the long term. It is essential, therefore, to address the causes of the pain once the symptoms of pain or parasthesia have been relieved by the injection. Recurrence of symptoms is common in bursitis and tendinopathy, so appropriate advice on prevention is a vital part of the care package.

The ideal outcome is total relief of pain with normal power and full range of motion. This does not always occur but when local anaesthetic is used there should be significant immediate improvement to encourage both patient and clinician that the correct diagnosis has been made, and the injection accurately placed.

The patient should be told that the relief of pain might be temporary, depending on the strength and type of anaesthetic used, and the pain may return when this effect wears off. Some patients describe this pain as greater than their original pain. This might be due to the flare effect of the cortisone, which is thought to be caused by microcrystal deposition, or because of poor injection technique where the needle has been rammed into bone, but it is also possible that pain that comes back after some relief might appear to be worse. Any after-pain is usually transient and can be eased by application of ice or taking simple analgesia.

The anti-inflammatory effect of the corticosteroid is not usually apparent until about 48 hours after the infiltration and can continue for 3 weeks to 2 months, depending on the drug used, so patients should maximize the drug action during this period by avoiding aggravating activities.

Arrange to review the patient about a week or 10 days later. If the pain is severe or begins to return, as occurs commonly in acute capsulitis of the shoulder, see that the patient knows that they can return for a further injection if necessary within this period.

Advise the patient on what to do and what to avoid in the intervening period. Joint conditions usually benefit from a programme of early gentle movement within the pain-free range ⁹; studies have shown that 24 hours’ complete bed rest after a knee injection for inflammatory arthritis is beneficial but in the case of the wrist immobilization does not appear to improve outcome and might even worsen it. Overuse conditions in tendons and bursae require relative rest; this means that normal activities of daily living can be followed, provided they are not too painful, but return to sport or strenuous repetitive activity should be postponed until the patient is as pain free as possible.

When the symptoms have been relieved, most patients will need a few sessions of treatment for rehabilitation and prevention of recurrence; this is particularly relevant in overuse conditions and might involve correction of posture, ergonomic advice, adaptation of movement patterns, mobilization or manipulation, deep friction massage, stretching and/or strengthening regimens. The advice of a professional coach in their sport or of an expert in orthotics might also be required.