W122 AJR:197, July 2011

can be used to image the hip joint, typically with frequencies around 9–15 MHz depend-ing on patient body habitus. Occasionally, a lower-frequency probe may be required if the patient is obese.

Providing an aseptic environment is of paramount importance in minimizing the in-troduction of infection, particularly when in-jecting into the joint itself. This essentially involves using sterile gloves and probe cov-ers; cleaning of the skin with an antiseptic skin preparation, such as chlorhexidine so-lution; and ensuring the needle tip passes through the cleaned area of skin, avoiding any areas of broken skin or overlying infect-ed areas. With the probe positioned over the hip joint in the sagittal plane, the femoral head is visualized and just superior to it, the acetabular roof and acetabular labrum. The labrum is a hyperechoic triangular structure attached to the brightly hyperechoic bone of the acetabulum (Fig. 1).

There are several important factors to consider that will aid a successful ultrasound guided procedure. Namely, always know where the needle is, have a good knowledge of the surrounding anatomy, and only inject when the tip of the needle is visible. The cru-cial factor in keeping the needle visible on the screen is to keep the probe and the nee-dle in the same place throughout the proce-dure. However, it is important to realize that the needle is best visualized when the needle and probe face are parallel. With increasing angle of insonation, the visualization of the needle becomes less clear and may even be-come invisible due to the reflection of sound

Ultrasound-Guided Intervention Around the Hip Joint

Emma L. Rowbotham1

Andrew J. Grainger

Rowbotham EL, Grainger AJ

1Both authors: Department of Musculoskeletal Radiology, Leeds Teaching Hospitals, Chapel Allerton Hospital, Chapeltown Rd, Leeds, West Yorkshire LS7 4SA, United Kingdom. Address correspondence to A. J. Grainger (andrew.grainger@leedsth.nhs.uk).

Musculoskeleta l Imaging • Review

WEB This is a Web exclusive article.

AJR 2011; 197:W122–W127

0361–803X/11/1971–W122

© American Roentgen Ray Society

Ultrasound of the adult hip is a commonly performed investiga-tion that may be used to assess for both intra- and extraarticular

pathology. Common findings include joint fluid, bursitis, hematoma, and paralabral cyst formation. Increasingly, ultrasound is being used to guide intervention around the hip joint for both diagnostic and therapeutic pur-poses. Ultrasound alleviates the need for ex-posure to radiation and is already the modal-ity of choice for aspiration of the hip joint [1], an intervention that may be helpful in guid-ing antimicrobial therapy and help avoid the need for surgical intervention. Ultrasound can also be used to access the hip for diag-nostic or therapeutic injection [2]. Guided in-jection of the greater trochanteric bursa or the iliopsoas tendon bursa may have enor-mous therapeutic benefits to the patient with-out the need for surgery or exposure to ion-izing radiation. We review some of the most common reasons for ultrasound intervention around the hip joint: intraarticular injection, aspiration of joint fluid for both therapeutic and diagnostic purposes, injection of tro-chanteric or iliopsoas bursitis, and treatment of the symptomatic snapping hip. We de-scribe the techniques used at our institution for these ultrasound-guided interventions, along with tips to aid a successful procedure.

Intervention TechniqueIn many cases, diagnostic ultrasound will

be performed at the same appointment as any appropriate intervention. With modern equipment, a high-frequency linear probe

Keywords: greater trochanteric bursa, hip, iliopsoas tendon bursa, ultrasound

DOI:10.2214/AJR.10.6344

Received December 14, 2010; accepted without revision December 28, 2010.

OBJECTIVE. The purpose of this article is to review some of the most common reasons for ultrasound intervention around the hip joint, and describe the techniques involved.

CONCLUSION. Ultrasound alleviates the need for exposure to radiation and is already the modality of choice for aspiration of the hip joint, an intervention that may be helpful in guiding antimicrobial therapy and help avoid the need for surgical intervention. Ultrasound can also be used to access the hip for diagnostic or therapeutic injection.

Rowbotham and GraingerUltrasound-Guided Intervention in Hip Joint

Musculoskeletal ImagingReview

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away from the probe (Fig. 2). Careful plan-ning of the needle path will allow exquisite visualization of the needle during the proce-dure. Marking of the skin at the chosen en-try point before injection is a valuable step in the procedure (Fig. 3). This allows the nee-dle to be positioned into the subcutaneous tissues first without the need for also hold-ing the transducer. The transducer can then be brought over the needle tip and the posi-tion confirmed before advancing the needle into the desired location. A 22-gauge needle is usually used for injections around the hip.

A larger bore needle, such as a 16 or 18 gauge may be needed for aspiration, particularly if the fluid is infected.

With all the described injections, a com-bination of local anesthetic and steroids is used to maximize symptom relief. The ste-roid used in our institution is 40 mg triam-cinolone and the local anesthetic is 1% lido-caine, usually in a volume of 5 mL. A recent study comparing the chondrocyte-damaging properties of local anesthetics used in joint injections has shown that 0.5% bupivacaine resulted in a reduction in chondrocyte den-

sity at 6 months when performed in vivo [3]. Consequently, we prefer the use of lidocaine for anesthetizing the skin and bupivacaine for intraarticular injection. The equipment needed for injection of the hip is shown in Figure 4.

Ultrasound-Guided Aspiration of the Hip

One of the most common indications for ultrasound of the adult hip is the detection and aspiration of a joint effusion. Pain in the groin or medial thigh, pain aggravated by ly-ing on the side, decreased extension or inter-nal rotation or abduction or flexion, painful external rotation, and pain on palpation in the groin showed a significant relation (ad-justed for age and radiologic osteoarthritis of the hip) with ultrasonic hip joint effusion [4]. The most common reason for aspiration in the hip is for the diagnosis of infection. How-ever, reliance on the ultrasound appearance of the effusion is not sufficient to distinguish between infection and a simple effusion. Pus can appear anechoic, and a complex appear-ance to the effusion does not reliably indicate sepsis (Fig. 5). The presence of a joint effu-sion is confirmed by an increased volume of fluid in the anterior recess. This is usu-ally measured in the oblique sagittal plane along the line of the femoral neck and should be compared with a measurement from the contralateral side (Fig. 6). The normal dis-tance from femoral neck to the capsule has been described as between 4 and 10 mm. It can sometimes be difficult to differentiate thickened synovium from joint effusion be-cause both have similar appearances on ul-trasound. If this is the case, asking the pa-tient to move the hip is helpful because this will disperse an effusion around the joint, whereas synovial thickening would remain constant in appearance. Aspiration of joint effusion is not always necessary and should be confined to patients in whom there is a high clinical suspicion of sepsis.

Ultrasound-Guided InjectionInjection of the hip joint is undertaken for

a variety of reasons. Inflammatory arthritides may be treated with direct injection of corti-sone into the hip. Similarly, symptomatic re-lief of osteoarthritis may also be achieved. Frequently, it is unclear whether a patient’s symptoms are due to hip pathology, for in-stance if the patient has both hip osteoarthri-tis and degenerative change in the spine. In this situation, a diagnostic injection of long-acting

A

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Fig. 1—Hip anatomy.A, Radiograph shows normal anatomy of hip in healthy subject. Plane of transducer (blue) is parallel to femoral neck.B, Sonogram in 28-year-old man shows hip joint with transducer placed in oblique axial plane along femoral neck (F) and corresponding normal anatomy of hip joint. Hyperechoic labrum is seen covering superior aspect of femoral head (blue arrow). There is small joint effusion seen at this hip joint (white arrow).

Fig. 2—Greater trochanteric bursa in 68-year-old woman.A, Normal radiograph from healthy subject (provided for comparison) shows probe position (blue) is placed along lateral aspect of hip in plane parallel to lateral surface of greater trochanter.B, Needle parallel to probe. Image shows needle (arrow) being introduced into soft tissues toward greater trochanter (GT) in plane parallel to transducer. This is optimal angle and entire needle is easily seen.

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anesthetic into the hip can help make the dis-tinction. We also make use of ultrasound guid-ance for the injection of contrast material for MRI arthrography. In this instance, the tech-nique is essentially the same as for therapeutic injection, with contrast medium instilled into the joint as opposed to local anesthetic and ste-roids. The introduction of contrast material for arthrography can be combined with diagnostic anesthetic injection if required.

Aspiration and Injection TechniqueFor both injection into the hip joint and as-

piration of the hip joint the patient should be positioned supine and the transducer placed in the longitudinal oblique plane along the axis of the femoral neck to examine the anterior recess and confirm the presence of effusion (Fig. 6). Intervention can be performed either in the axial or sagittal plane. In our institution, the axial plane is preferred because it allows

the needle to be introduced almost parallel to the probe face. This technique also means the skin puncture is made laterally, well away from the medially located neurovascular bun-dle. This enables the operator to place the nee-dle and then confirm position with the ster-ile probe. For aspiration, the needle should be placed into the deepest pool of fluid within the joint and aspirated into a sterile syringe. Sam-ples should be sent for culture and sensitivity. Aspiration should be as complete as possible to maximize relief of symptoms.

As with aspiration of the hip, we prefer an axial approach to the hip joint for injection. The femoral head is identified and the probe is then positioned to obtain an axial view through the head. Sweeping the probe distally identi-fies the junction of the femoral neck and head

in the axial plane, which is the point targeted for the injection. The needle is introduced from the lateral side along the long axis of the probe and as parallel to the probe face as is feasible. When the needle is seen (and felt) to contact the bone, it will lie within the joint on the antero-lateral aspect of the head–neck junction (Fig. 7). A sterile technique is again of paramount importance, and marking the skin at the ap-propriate needle entry point before preparing the sterile equipment is helpful. A combination of local anesthetic and steroids should be pre-pared in the same syringe. The injectate should be placed into the anterior recess at the femoral head–neck junction (Fig. 8). Unless the exam-ination is being undertaken for arthrography,

A

Fig. 3—Photograph shows hip injection skin marking in 32-year-old woman. Marking of skin before injection allows accurate placement of needle into tissues and then placing probe back onto skin to guide final positioning. This image shows marking of skin before hip joint injection with probe in axial plane.A and B, Axial ultrasound image (B) shows corresponding normal anatomy with probe in axial plane as in A. Labrum is indicated with blue arrow and psoas muscle overlying femoral head (F) is indicated with white arrow.

Fig. 4—Photograph shows injection equipment. Chlorhexidine cleaning sticks are now used for all procedures at our institution, and 1% lidocaine is usually adequate for subcutaneous analgesia. Duraprene manufactured by Allegiance Healthcare.

Fig. 5—Complex hip effusion in 74-year-old woman. There is large amount of complex fluid (arrow) seen within hip joint in patient who has had dynamic hip screw inserted into femoral head–neck after fractured neck of femur (F). Hip aspirate revealed frank pus within joint and patient was taken to theater for washout of septic joint.

B

AFig. 6—Axial oblique approach to hip joint in 82-year-old woman.A, Photograph shows transducer placed in axial oblique plane along femoral neck and needle placed into soft tissues along line of transducer.B, Sonogram shows hip effusion (arrow). In this case, effusion has been measured (calipers) in anteroposterior direction and measurement was compared with contralateral side to confirm presence of effusion.

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it is helpful to inject a little air at the start of the injection. This is easily seen on ultrasound and confirms the intraarticular location of the injection. If the patient is to undergo MRI ar-thrography, the presence of air is to be avoided because it may be confused for pathology, such as intraarticular loose bodies.

The patient should be warned that there might be an aching sensation in the hip in the 24 hours after injection and, when cor-tisone has been injected, that the maximal therapeutic benefit may not be experienced for several days after the procedure.

Ultrasound-Guided Injection of the Greater Trochanteric Bursa

Trochanteric bursitis is a relatively com-mon condition affecting physically active pa-

tients and usually presenting with pain to the lateral aspect of the hip, particularly on walk-ing. This condition either occurs secondary to an injury—usually overuse injury—or more rarely as a manifestation of rheumatoid ar-thritis. Traumatic injury includes bursal irri-tation as a result of the iliotibial band mov-ing over the bursa repetitively and is usually seen in athletes. The trochanteric bursa is best thought of as a bursal complex with bursae present between the gluteal tendons. The tro-chanteric bursa itself is often described as be-ing situated between the iliotibial tract and the gluteal tendons (Fig. 9). In addition there is a subgluteus medius bursa beneath the glute-us medius tendon, and similarly, a subgluteus minimus bursa. Inflammation of any of these bursae will present with lateral hip pain. The

gluteus medius and gluteus minimus mus-cles have been described in the literature as the “rotator cuff of the hip,” and tendinopathy or tears of these two muscles have also been shown to be present in most patients present-ing with trochanteric bursitis [5].

Greater Trochanteric Bursa Technique

The trochanteric bursae are best approached with the patient lying on the side in the lateral decubitus position with the symptomatic side uppermost (Fig. 9A). The bursae are relatively superficial structures and therefore readily ac-cessible. The superficial position also makes keeping the probe face and needle track paral-lel relatively easy. Both axial and sagittal imag-ing will show fluid within the bursa, provided not too much pressure is applied with the trans-ducer, which may compress the inflamed bur-sa. As in assessment of joint effusion, compari-son with the contralateral side is useful when findings are equivocal. Again, sterile condi-tions are essential. A combination of local an-esthetic and steroids (typically 40 mg triamcin-olone) should be prepared and injected into the fluid collection (Fig. 10).

Ultrasound-Guided Treatment of Iliopsoas Pathology

When the patient moves the hip through cer-tain positions, snapping of the iliopsoas tendon over the iliopectineal eminence may cause an audible snap or click that can be painful and felt anteriorly. This condition may occur sec-ondary to previous trauma or injury, particu-larly overuse injury [6]. The iliopsoas muscle functions as a hip flexor and arises from the

Fig. 7—Hip injection video in 71-year-old man. This animation shows needle entering tissues distal to hip joint and then being guided to hip joint before injecting mixture of local anesthetic and steroid into joint space under ultrasound guidance. For this video, see Figure S7 in supplemental data at www.ajronline.org.

Fig. 8—Sagittal sonogram of hip joint in 68-year-old woman shows femoral head (F) and needle within hip joint (arrow) immediately before injection. (See also Fig. S8, cine loop, in supplemental data at www.ajronline.org.)

A

Fig. 9—Trochanteric bursitis injection position in 57-year-old woman.A, Photograph shows position of transducer in longitudinal plane with relation to greater trochanter. Position of proximal end of transducer has been marked before injection.B, Trochanteric bursa (blue arrow) is thickened in this axial image and shows echo-poor line immediately adjacent to bone cortex, in keeping with trochanteric bursitis. Gluteus medius bursa is also thickened in this example (white arrow). GT = greater trochanter.C, Further more florid example of trochanteric bursitis (arrow) is shown in this longitudinal image. GT = greater trochanter.

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anterior inferior iliac spine and inserts into the lesser trochanter of the femur. A similar sen-sation is produced by the iliotibial band snap-ping over the greater trochanter but is felt in a lateral position and usually felt as the hip moves from extension to flexion. Iliopsoas ten-dinopathy is a recognized complication in pa-tients who have had hip replacement surgery [7]. It may be possible to show impingement of the iliopsoas tendon on a prominent aspect of the hip arthroplasty. It is important to exclude other pathology that may present with similar symptoms, such as labral tears, cartilage de-fects, and intraarticular loose bodies.

Ultrasound can be used to show the ilio-psoas muscle flipping over the iliacus muscle to confirm the diagnosis of snapping iliopsoas (Fig. 11), and in many cases an associated ilio-

psoas bursitis will also be visualized. Iliopsoas bursitis may also be seen be seen in isolation and is treated the same way.

In some cases, surgical intervention is neces-sary to alleviate symptoms, but a combination of local anesthetic and corticosteroid injection can often provide symptomatic relief and avoid the need for surgery. The injection is performed into the iliopsoas bursa or, in the absence of a bursa, deep to the iliopsoas tendon. Failure of the injec-tion to provide symptomatic relief suggests that an alternative pathology may be responsible for the patient’s hip or groin pain.

Iliopsoas TechniqueWith the probe oriented along the femo-

ral head and neck, the iliopsoas tendon can be seen to lie lateral to the neurovascular

bundle. The patient is best positioned in the supine position. A combination of local an-esthetic and steroids is again required. The approach is similar to that used to inject the hip in the axial plane. By positioning the probe over the bursa or tendon, the needle can be advanced in the lateral side of the thigh, parallel to the probe face, maintain-ing exquisite visualization. Injection typical-ly comprises 40 mg of triamcinolone mixed with a small amount of lidocaine.

Complications of Ultrasound-Guided Intervention Around the Hip Joint

Complications after ultrasound-guided in-tervention at the hip are not common. How-ever, as with every interventional procedure, complications do occasionally occur. The most common include infection both at the punc-ture site and of the hip joint itself, bleeding into the joint, and injury to the femoral nerve. Al-lergy to the local anesthetic may present with systemic symptoms of headache, dizziness, circumoral numbness and tachycardia, or lo-cal symptoms related to nerve damage, such as paraesthesia or prolonged anesthesia.

Introducing infection into the joint is rare, but if it occurs it may have long-term con-sequences in terms of damage to the joint. Patients should be informed of this potential complication when giving consent for the procedure to be performed. Aseptic condi-tions minimize this risk, but patients should be aware that ongoing or worsening symp-toms accompanied by redness and swelling around the joint may be a sign of infection.

Bleeding into the joint is minimized by ensuring the international normalized ra-tio is below 1.5. Patients on anticoagulation therapy should be advised to stop the therapy before the procedure is performed.

Injury to the femoral nerve is rare but is documented in the literature [8]. This is usu-ally temporary and results in diminished sen-sation over the anterior thigh and inability to flex the hip or put weight on the extremity. One of the major advantages of ultrasound guidance over fluoroscopy for intervention around the hip is that the femoral nerve and other neurovascular structures are well visu-alized and therefore injury is minimized.

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Fig. 10—Needle position in greater trochanteric bursa in 68-year-old woman.A and B, Sonograms show start (A) and end (B) positions of needle as it is positioned into greater trochanteric bursa as shown in video Figure S10A (available in supplemental data at www.ajronline.org).A shows needle (blue arrow) entering tissues proximal to greater trochanter (GT) and greater trochanteric bursa (white arrow), and B shows final position of needle in trochanteric bursa immediately before injection. Needle (blue arrow) is seen clearly with tip in bursa (white arrow).

Fig. 11—Snapping iliopsoas tendon in 27-year-old man.A and B, Sonograms show start (A) and end (B) of snapping iliopsoas tendon (IP) (blue arrow) as it flips across iliopectineal eminence of pelvis. (See also Fig. S11A in supplemental data at www.ajronline.org).

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F O R Y O U R I N F O R M A T I O N

The data supplement accompanying this Web exclusive article can be viewed from the information box in the upper right corner of the article at: www.ajronline.org.

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