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Hip injection using image intensifier

    Overview

    Learn the Hip injection using image intensifier surgical technique with step by step instructions on OrthOracle. Our e-learning platform contains high resolution images and a certified CME of the Hip injection using image intensifier surgical procedure.
    Intra-articular injection of the hip joint has a number of potential indications. Therapeutically these range from traditional anti-inflammatory steroid injections to newer interventions such as Platelet Rich Plasma (PRP) injections or visco-supplementation with Hyaluronic acid, for the treatment of early osteoarthritis. Diagnostic injections into the joint with short acting local anaesthetic agents are commonplace to demonstrate the source of pain as being intra-articular and from the hip.
    A hip injection is in most cases a straightforward procedure and there are a variety of techniques and approaches to use. There are also different modalities of imaging to aid the approaches, which are discussed in the alternative techniques section.
    The technique I describe is a simple, safe and reproducible way of reaching the hip joint. This is my favoured technique as the imaging of the needle in profile along the femoral neck is an easy visual aid to correct positioning.

    Indications

    INDICATIONS
    Pain relief – a therapeutic injection in a patient with known arthritis or synovitis
    Diagnostic – an injection to differentiate between intraarticular and extraarticular pain.
    Aspiration – for diagnostic purposes to investigate infection or metallosis.
    SYMPTOMS & EXAMINATION
    Intraarticular hip pain is often described with groin pain, anterior or lateral thigh pain and buttock pain. This is often worse with flexion activities such as putting on shoes, sitting on a ow chair or ascending stairs. Rotational movements are painful and difficult such as getting into a car. Patients are often taking analgesia, can be awoken with night pain, and have limitations in activities of daily living.
    Examination often reveals stiffness in flexion or rotation (particularly internal rotation). Pain can be reproduced either globally with and movement (such as internal or external rotation) or more specifically (such as a positive impingement test which is classically described as reproducing the patients ‘familiar’ pain on flexion, adduction and internal rotation)
    Differentiating between intra and extra-articular causes of pain can be difficult clinically. Psoas tests such as hip circumduction (moving the leg from a flexed to extended position) can reproduce psoas pain or clicking. Gluteal symptoms are usually felt laterally, with difficulties lying on the side in bed at night or with gait. Tests for gluteal function such as Trendelenburg testing or even more subtle testing with a single leg mini dip test can be useful to differentiate. The Trendelenburg test is performed by standing in front of the patient with their hands on yours to feel for weight transfer, asking them to balance on one leg and then perform a half squat. A positive test is when the knee of the stance leg drifts medially into valgus confirming a degree of gluteal weakness.
    These tests along with others can be found in the results section with a reference for further reading on clinical examination
    The use of a ‘diagnostic’ injection is seen as a final part of examination particularly if the patient can be examined pre and post injection.
    IMAGING
    Pre-operative imaging should consist of at least a plain radiograph to assess the underlying pathology. Other modalities such as MRI and CT are often used in non arthritic conditions to aid diagnosis.
    Plain radiographs can be looked at in the context of arthritis with the classical loss of joint space, osteophyte formation, subchondral cysts and sclerosis. They can also provide information on at least the two-dimensional shape of the hip. On the acetabular side, measurement of the centre edge angle will confirm dysplasia (<20 degrees) or over-coverage (>45 degrees). On the femoral side, Cam shape abnormalities may be seen with either a flattening of the superior head neck junction or the appearance of an anterior Cam as a ‘hanging rope sign’
    CT scanning is useful for showing in more detail and in three-dimensions the bony shape of the femur and acetabulum. Subtle early joint space loss such as posters-inferior joint space can be seen easily on axial images. Three-dimensional reconstuctions can also be useful for surgical planning.
    MRI scanning is useful for helping to exclude/confirm extra-articular pathology such as Psoas inflammation, gluteal inflammation or tears. The use of an MRI scan to confirm a labral tear depends on the quality of both the images and the report and personally, I would prefer to use clinical examination and history to decide on treatment strategy and purely use the MRI scan to exclude other pathology.
    ALTERNATIVE OPERATIVE TREATMENT
    Other approaches for injections are often used. They all require knowledge of the cross sectional anatomy of the hip region as shown in the MRI images later in the technique. The position of the neurovascular bundle starting at the midpoint of the inguinal ligament at that level and progressing deeper but more medially as it moves vitally into the thigh. Hip injections should always be image guided but the use of other imaging modalities such as ultrasound can be as useful as using an image intensifier but obviously require training in sonography.
    The Regular injections for pain relief should be avoided if possible. If the underlying pathology would be amenable to surgery such as hip replacement the benefits and risks of such surgery should be discussed with the patient.
    NON-OPERATIVE MANAGEMENT
    Analgesia and activity modification can obviously be used to reduce symptoms. In certain pathologies, physiotherapy can be used to either optimise function or reduce symptoms (such as in Femoro-Acetabular Impingement).
    CONTRAINDICATIONS
    Injection through an area of active infection should be avoided (for example an area of cellulitis)
    Injection through a neoplastic lesion should be avoided
    Injection in the presence of hip infection (unless used as a diagnostic aspiration)
    Injection in the presence of systemic infection (such as a UTI or chest infection) should be a considered decision between benefits and risks

    Setup

    Although injections can be performed in the clinic or radiology department, for both ease of set up, sterility and access to sedation, I prefer to undertake my injections in theatre.
    The theatre requires adequate space for an image intensifier. Positioning of the C arm should have it coming in from the opposite side of the hip to be injected. The screens should be placed in a position towards the head, again on the opposite side of the patient (you will be stood beside the patient facing the head and do not want to be twisting to look at the screen)
    The operating table needs to be radiolucent, at least in the portion where the hip will be positioned.

    Operation

    The Patient is positioned supine on the operating table, ensuring the hip area (from the iliac crest to the knees) is accessible for the image intensifier. It is worth taking a preliminary image before you prep the skin in case you have to reposition the patient.
    The skin is exposed, again from the iliac crest to the knees, ensuring any underwear worn is able to be moved at least to the midline or should be removed.
    As I perform my injections in theatre, I prefer to use the anaesthetist to give the patient some IV sedation rather than perform under Local Anaesthesia. I feel that the pain and distress of the whole process is less and that the accuracy of post injection examination is improved due to this (see post op section).

    The skin is prepared as standard. I prefer to formally prep with a swab and alcoholic betadine rather than use chlorhexadine spray as it is easier to ensure the whole area had been adequately sterilised.

    The Anterior Superior Iliac Spine (ASIS) can be marked with a sterile marker pen for orientation (A). A vertical line drawn down from this can be used to mark the lateral portion of the thigh that must be used to avoid endangering the neurovascular structures.
    At the level of the inguinal ligament, they sit midway between the ASIS and the pubic tubercle. They can be seen on the cross sectional images later in the technique. They can be palpated if necessary with the femoral pulse felt at the midpoint described.

    It is useful to draw up all the drugs you intend to inject before you start. If all your syringes are lined up on your trolley in order, a slick process of spinal needle insertion to complete injection can be as quick as 30 seconds.
    For a purely diagnostic injection I would use 10mls of 0.5% Chirocaine (Levobupivicaine) as it has a proven lower chondrotoxicity than Marcaine (Bupivicaine).
    For Diagnostic/Therapeutic injections I would add in 80mg of Depomedrone for long lasting anti-inflammatory action.
    Injections into the hip of Hyaluronic acid (HA) or Platelet Rich Plasma (PRP) can be useful in certain situations but I actually prefer to use a slightly different technique which will be separately described.

    The spinal needle (ideally 18g) is initially left in its sheath and placed on the skin in the anticipated orientation of the femoral neck. This is confirmed with the image intensifier and adjusted until the needle is parallel with the neck and central or in the upper 1/2 (see next slide)
    To optimise the view the foot can be internally rotated by an assistant until the femoral neck is in its best profile (the angle is actually equal to the degree of anteversion of the neck). This is normally with the foot at least vertical or slightly internally rotated.

    The sheath is left in place as a guide (or can be pressed into the skin to leave a mark) and the needle inserted from a lateral entry point following the orientation of the sheath. In the sagittal plane, this at the midpoint of the femoral neck and lateral enough to be in line with the lateral edge of the greater trochanter. The angle of puncture is normally approximately 45 degrees (antero-posterior) but depends on the depth of soft tissues and the length of the femoral neck.
    The aim is to penetrate the capsule close to the head neck junction but not so close as to risk damaging the articular cartilage or labrum

    The needle normally penetrates the skin at or just above the level of the lesser trochanter, just lateral to the lateral femoral cortex (point A)

    At the level of the entry point, the needle is just lateral to the sartorius and tensor fascia lata muscle belly (A) and importantly, well away from the neurovascular bundle (B)

    At the level where the needle penetrates the capsule, the neurovascular bundle is closer to the anterior acetabulum (A) but still well away from the needle. This again emphasises the line drawn vertically down from the ASIS beyond which you should not deviate medially.
    The Psoas can be seen here, closely opposed to the anterior femoral neck and can therefore be targeted in this area if required (usually easier in the inferior part of the neck)

    Once the needle penetrates the capsule and touches bone, the orientation of the bevel should be checked to ensure it is facing towards the bone (this ensures penetration of the capsule and reduces the risk of extravasation). When first learning the technique it can be worth screening a few times as the needle progresses to ensure it is not deviating off the femoral neck.
    Rather than using contrast, a simple air arthrogram can be obtained by injecting 10mls of air (this can be filtered by drawing it up using a drug filter). The image quality is as good as using contrast with the advantage that if required, contrast can be used into other locations (such as the psoas sheath) and the two locations can be differentiated.
    If you are unable to gain an arthrogram with the first pass t is essential to screen the position to ensure the needle is over the neck, then ensure it has advanced right down to bone and then if necessary back out slightly to allow the air to inflate the capsule.

    The radiographer can ‘cone in’ the image at this stage as the needle position in fixed. It is easy to see the air within the joint cavity and with experience it can even be used to assess the position and shape of the labrum (much like a ‘rosethorn sign’ in paediatric hip arthrograms where the outline of the labrum can be seen off the edge of the acetabulum sticking out like a ‘rosethorn’)

    Once the position has been confirmed with the image intensifier, the hip is injected with the chosen drugs. It is easier to inject from a small (5-10ml) syringe and if necessary multiple syringes can be used depending on what you plan to inject.
    If it is difficult to inject, the position can be checked but also, the capsular tension can be improved by an assistant lifting the knee slightly to give a degree of hip flexion (this may be up to about 30 degrees) . These needs to be done gently to avoid bending the needle. However, the chance of a spinal needle breaking is very small due to their flexibility.
    The hip can be moved post injection (flexion and rotation) to ensure adequate spread of fluid and can also be used to assess positions of impingement or instability under the image intensifier if necessary.

    The entry point is covered with a sterile dressing which can be removed the same day with no wound care required.

    It is of course possible to use this technique for joint aspiration as well as injection. This is useful in the context of diagnosing infection in a native or replaced hip.
    In such cases, it is better to aspirate the hip before attempting to inject air or contrast. If the aspirate is ‘dry’ once the position is confirmed with the arthrogram, you can inject 10mls of saline and then withdraw the fluid once it has had time to bathe the joint.

    Depending on your local microbiology guidelines, the sample can be divided up between two blood culture bottles, a sterile container and a blue topped blood bottle. A small drop can also be placed on a leucocyte esterase (urine dipstick) to test for infection or a commercially available test strip (although at much greater cost). The test strips are particularly useful if you need to make a decision on urgency of operative treatment (if positive, proceeding to revision surgery under the same theatre sitting).

    Post Operative

    The accuracy of an injection for diagnostic purposes can be increased if the patient is examined pre and post-operatively. Movements that provoke pain (such as an impingement test) can be repeated in the recovery room for immediate diagnostic use.
    If patients only have been experiencing pain with very specific movements (such as kicking or ‘cutting’ in a sports person)it can be useful to send them to perform these activities in the first few hours post injection. The Local anaesthetic part of any injection is by far the ‘strongest’ at relieving symptoms but will last less than 24 hours.
    Beyond this time it is still useful for patients to complete a pain diary and bring it to a follow up appointment to discuss. It is useful to have written records as a patients memory is often not as accurate even after just a few weeks.

    Recommended Reading

    Clinical diagnosis in hip disease. MD Cronin, MJK Bankes. The young adult hip in sport (F Haddad ed.) Book chapter: 27-32.
    This book chapter provides a good overview of the clinical examination and techniques used in the diagnosis of all intra- and extra-articular hip pathology.

    Outcomes After Diagnostic Hip Injection. Lynch TS, Steinhaus ME, Popkin CA, Ahmad CS, Rosneck J. Arthroscopy. 2016 Aug;32(8):1702-11.
    This recent systematic review confirms that diagnostic hip injection is a stronger predictor of surgical outcome than clinical findings or imaging. The response appears best in chondral injury and least in Cam impingement.

    Septic arthritis in Iceland 1990-2002: increasing incidence due to iatrogenic infections. Geirsson AJ, Statkevicius S, Víkingsson A SO. Ann Rheum Dis. 2008;67(5):638.
    A review of the incidence of septic arthritis confirms that although the risk increases with increasing use of injections and arthroscopy, the risk with injection was found to be 0.o37% compares with 0.14% with arthroscopy

    Reference

    • orthoracle.com

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