Joint and soft tissue injections

JOINT and soft tissue injections are commonly used to help ease the discomfort and loss of function associated with musculoskeletal disorders. They are a safe and effective treatment option for many patients and generally perceived to be a low-risk intervention. However, the complaints and claims against doctors performing such injections are not infrequent.

There is little firm evidence on which to base best practice in this area and as a result there is variability regarding exactly how and when such injections are used in clinical practice. But there are certain considerations which can enhance patient safety and help clinicians avoid some of the medico-legal pitfalls. The following article is based on guidelines for joint and soft tissue injections which have recently been developed by the Primary Care Rheumatology Society.

Before treatment

As with all medical procedures, any clinician undertaking joint and soft tissue injections must be adequately trained and have up-to-date clinical skills. Ensure all medication or other equipment is appropriate for the intended use and in date. For example, some steroid preparations vary in clinical indication yet the packaging and constituents can be similar.

Ensure enough time is available to explain the procedure. Consent for joint injection requires the same rigorous attention to detail as other interventional medical treatments. The patient must be informed about the nature of the injection, relevant risks and benefits and alternative treatment options. A patient information leaflet can aid patient understanding and decision-making and also helps ensure that no important contraindications or adverse effects are overlooked. A suggested leaflet is available on the PCRS website.

Clear documentation must be made of the above discussion and that the patient has consented to the treatment. Signed consent is not required in the UK but may be used in addition to the above documentation. Further information regarding consent can be found on relevant MDDUS and GMC web pages.

Contraindications to joint and soft tissue injections include:

• allergy to local anaesthetic, steroid, proposed skin cleanser or dressing
• local or systemic infection
• active rash/broken skin at site of injection
• uncontrolled coagulopathy
• fracture/unstable joint
• tendon regions at risk of rupture
• injection into a prosthetic joint or surgical metal work in situ
• imminent surgery at the site of or close to the proposed injection.

Anticoagulant therapy is not a contraindication to joint injection but precautions apply. You should discuss the risks of continuing or stopping anticoagulation with the patient and ensure a management plan is in place should a bleeding complication occur.

Several studies suggest that joint and soft tissue injections can be safely carried out provided the INR is within the therapeutic range. This should therefore be checked prior to the procedure. For patients taking novel oral anticoagulants, given the shorter half-life, consideration should be given to avoiding interventional procedures during peak drug activity – for example for rivaroxaban this peak would be 2-4 hours after the last dose.

Procedure and associated risks

When positioning the patient, be prepared for the possibility they may faint during or after the injection. Ensure that they will not get injured should this occur. When marking the skin, avoid using an ink marker directly at the site where the needle is to be inserted or a permanent tattoo may result.

Potential risks associated with joint and soft tissue injections include:

• infection
• soft tissue atrophy and local depigmentation
• tendon rupture
• nerve damage
• menstrual disturbances
• disturbance in glycaemic control in diabetics
• allergic reaction.

Infection

Infection is considered a rare complication of joint and soft tissue injection, however the consequences can be catastrophic. The patient should be warned in advance about the serious consequences of infection, what symptoms may occur and how to seek immediate medical attention if required.

Dust covers on vials of medication are not necessarily adequate to ensure sterility of the outside of the vial top. Therefore swabbing the vial with a sterile alcohol swab is recommended for some medications.

Skin preparation is generally recommended prior to surgical procedures to reduce the numbers of skin bacteria – although there appears to be little published information on infection rates when no skin cleaning has been carried out prior to joint injection. There have been rare recorded incidents of infection resulting from contaminated topical antiseptics. All skin cleansers should be used strictly in accordance with the manufacturer’s instructions. Consideration should be given to single-use skin preparations labelled as sterile.

Once the skin has been prepared, use a ‘no touch’ technique when injecting unless full sterility is observed.

Soft tissue atrophy

Soft tissue atrophy and local depigmentation are uncommon complications of steroid injection. Although these are predominantly cosmetic effects, at some sites such as the heel pad, atrophy can be clinically significant and may persist for years. Atrophy may be due to the persistence of steroid crystals in the tissues and seems less likely to occur with more soluble preparations, e.g. hydrocortisone and methylprednisolone. These are therefore preferred for soft-tissue, small-joint and superficial injections. Should concerning soft-tissue atrophy occur, referring the patient for a course of local injections of saline may be helpful.

Tendon rupture

The risk of tendon rupture attributed to steroid injection, for example at the shoulder, is somewhat controversial. However, it has been demonstrated in animal studies that intra-tendinous injections of steroid can result in collagen necrosis and weakening of the tendon, potentially lasting for several weeks. Therefore if injecting in peri-tendinous regions where there is a risk of suboptimal needle placement, avoid injecting if resistance is encountered and consider the use of image guidance if available. Generally avoid injecting regions where concern regarding the risk of tendon rupture is high, for example at the Achilles tendon.

Nerve damage

Ensure you are familiar with the anatomy of the injection site to avoid inadvertently injecting a nearby nerve. In neuropathies (e.g. carpal tunnel syndrome) the affected nerve may be swollen and therefore anatomical landmarks may be less reliable. Before injecting, ask the patient to report symptoms of nerve activation when the needle is inserted. Withdraw and reposition the needle if this occurs. Avoid local anaesthetic at such sites if this may prevent the patient reporting symptoms of nerve irritation. Consider image-guided injections.

Menstrual disturbances

Effects on the hypothalamic-pituitary axis are thought to be responsible for the menstrual irregularities or vaginal bleeding seen in some women after steroid injections. It is important to warn of this effect, which may persist for several weeks, to avoid unnecessary alarm or investigations.

Facial flushing may also occur follow a steroid injection. This is not an allergic reaction and does not preclude future injections. This side-effect generally affects women and can be dramatic and distressing, particularly if not forewarned.

Glycaemic control

Small increases in glycaemia lasting a few days may be seen after steroid injections in diabetic patients. The increase is generally not clinically significant but again it is sensible to warn patients.

Allergic reactions

Although allergic reactions are rare, full resuscitation equipment must be readily accessible and staff available and trained to use it in all locations where injections are performed. According to the Resuscitation Council UK website, cardiopulmonary arrest resulting from injected medication predominantly occurs up to 20 minutes post injection. It would seem sensible therefore for patients to remain on site for this time.

PCRS guidelines

Comprehensive guidelines on joint and soft tissue injections can be found in the Resources section of the Primary Care Rheumatology Society website: http://www.pcrsociety.org/

Dr Lucy Douglas is a GP with special interest (GPwSI) in musculoskeletal medicine and rheumatology