Ultrasound-guided intra-articular injection therapy

Learning objectives.

By reading this article, you should be able to:

• •Describe the clinical applications of ultrasound-guided intra-articular (IA) injections.
• •Identify commonly used injectables for managing joint diseases.
• •Explain the fundamental principles underpinning ultrasound-guided joint injection approaches.

Key points.

• •Ultrasound-guided intra-articular (IA) injections enhance drug bioavailability and minimise systemic adverse effects by delivering therapeutic agents directly into the joint space.
• •Intra-articular injections play a crucial role in pain relief, rehabilitation, diagnostics and cartilage repair and regeneration.
• •Ultrasound-guided IA injections for peripheral joints offer real-time, radiation-free imaging while achieving comparable clinical outcomes to fluoroscopy-guided injections.
• •Recent advances in IA therapy include strategies to extend drug retention and controlled-release formulations.
• •Current IA injectable therapies include corticosteroids, hyaluronic acid, platelet-rich plasma, mesenchymal stem cells and prolotherapy.

Intra-articular (IA) injections offer a targeted alternative to systemic drug delivery, addressing challenges such as limited bioavailability and systemic adverse effects by delivering therapeutic agents directly into the joint space. The origins of IA therapy can be traced back to 1792, when Jean Gay, a French physician, performed one of the earliest documented IA injections when he injected eau de Goulard (Goulard's water), a lead-based solution, into a swollen knee joint to treat inflammation.¹ In the 19th century, Alexander Wood, a Scottish physician, and Charles Gabriel Pravaz, a French surgeon, advanced IA techniques through the development of hollow needles and syringes, and since the discovery of corticosteroids by Joseph Lee Hollander in the mid-20th century, IA injections have become widely used for the management of inflammatory joint disorders.¹

Initially reliant on surface anatomical landmarks for guidance, IA injection techniques advanced significantly with the introduction of fluoroscopy in 1896. By the mid-20th century, fluoroscopy had become widely adopted for joint injections, enhancing accuracy by guiding needle placement within the joint space.² More recently, ultrasound guidance has gained prominence, offering several advantages over fluoroscopy, including portability, real-time needle guidance, radiation-free imaging and the ability to visualise soft tissues. A 2023 systematic review of 66 studies, primarily RCTs, compared the accuracy of IA injections guided by anatomical landmarks, fluoroscopy and ultrasound in various peripheral joints. Both fluoroscopy and ultrasound significantly improved the accuracy of injection compared with palpation-guided methods, with no difference in precision between the two imaging techniques.³

This article explores the clinical applications of IA injections, examining IA drug delivery strategies and injectables, and also ultrasound-guided injection techniques for commonly targeted large, medium and small joints in the upper limb, lower limb and axial skeleton, excluding the spine.

Intra-articular injections in joint disease management

Intra-articular injections are used in various branches of medicine to manage joint conditions. In pain management, IA injections are often considered for both acute and chronic joint pain. For example, corticosteroid injections are commonly used for painful episodes of acute gout and chronic pain associated with osteoarthritis (OA) and rheumatoid arthritis (RA).^4,5 These injections are typically given when conservative therapies are ineffective, particularly when surgery is unsuitable or when patients aim to avoid or delay surgical interventions. For example, IA corticosteroid injections into the first carpometacarpal joint (CMCJ) are effective in reducing OA pain, improving function and delaying surgical procedures such as trapeziectomy.⁶

In rehabilitation medicine, IA injections often serve as adjuncts to physical therapy, enhancing the effectiveness of comprehensive rehabilitation programmes. A notable example is shoulder joint hydrodilatation for the treatment of adhesive capsulitis. This technique involves stretching the joint capsule by injecting a large volume of normal saline combined with corticosteroids and a local anaesthetic, helping to break down adhesions, improve range of motion and provide effective pain relief.⁷

As a diagnostic tool, IA injections are invaluable for evaluating joint pain, particularly in cases with overlapping symptoms. A common approach is the use of preoperative IA injections to confirm or rule out the joint as the primary generator of pain, before surgery. For example, injecting a local anaesthetic into the hip joint can help determine whether hip OA is the main pain generator, especially in patients presenting with concurrent low back pain—a scenario affecting up to 10% of individuals. This method effectively differentiates between coxarthrosis and referred pain, guiding treatment decisions such as arthroplasty.⁸

In regenerative medicine, IA injections of orthobiologics such as platelet-rich plasma (PRP) and mesenchymal stem cells (MSCs) are used to support tissue repair and cartilage regeneration. These therapies are commonly used in managing chronic degenerative conditions, such as mild-to-moderate knee OA.⁹ They also serve as adjuncts to enhance recovery and promote healing after joint surgeries, such as meniscus repair of the knee joint.¹⁰ Beyond the rapidly advancing field of injectable orthobiologics, IA gene therapy represents an innovative approach under active investigation. This technique focuses on the precise delivery of genetic material to modify underlying disease mechanisms, such as those observed in OA. Gene therapy can be given through the direct injection of vectors into the joint to promote localised gene expression or ex vivo, in which cells are externally modified and then reintroduced via IA injection.¹¹

Intra-articular drug delivery

When given systemically, soluble molecules, typically those smaller than albumin (∼7 nm), can enter the joint cavity through synovial capillaries. However, these molecules generally arrive in lower concentrations and are rapidly cleared via lymphatic pathways, limiting their therapeutic efficacy.¹² Intra-articular injections address these limitations by delivering therapeutic agents directly into the joint cavity, achieving higher local concentrations. Common strategies to prolong the duration of IA drugs within the joint include using microparticles, liposomes and hydrogels.¹³

Microparticles, such as crystalline suspensions and microspheres, form depot suspensions (i.e. slowly dissolving deposits) that resist rapid clearance because of larger particle size (greater than albumin) and low solubility. Examples include triamcinolone acetonide (10–20 μm) and methylprednisolone acetate (∼10 μm), both of which form crystalline suspensions upon IA injection.¹³ Extended-release triamcinolone acetonide (25–35 μm), formulated with microspheres composed of poly (lactic-co-glycolic) acid, enables controlled drug release through gradual polymer degradation.¹⁴

Liposomes, composed of lipid bilayers, encapsulate both hydrophilic and hydrophobic drugs, enabling controlled release and prolonged retention, as seen with liposomal bupivacaine.¹⁵ Hydrogels, such as hyaluronic acid (HA), form a three-dimensional matrix that slows drug release and retains co-injectates by enhancing synovial fluid viscosity.¹⁶

Biomechanical factors also influence the duration of action of IA drugs. Joint movement can increase synovial fluid circulation, expediting injectate clearance through lymphatic and vascular pathways.¹⁷ Although practitioners typically advise against overuse of injected joints for 24 h after IA therapy, complete immobilisation is generally discouraged. Studies suggest that 24–48 h of immobilisation (e.g. bed rest, joint splinting or bandaging) provides no additional benefit over normal activity.¹⁷

Although prolonging the duration of IA drugs within the joint has therapeutic advantages, careful management is essential to mitigate potential risks. Prolonged exposure to high concentrations of certain drugs, such as corticosteroids, may induce cartilage degeneration via chondrocyte apoptosis.¹⁸ Similarly, local anaesthetics such as bupivacaine and lidocaine show dose- and time-dependent chondrotoxicity. Ropivacaine is less chondrotoxic and may be a safer alternative for repeated IA anaesthesia.¹⁸

Intra-articular injectables

Corticosteroids, the most commonly used injectables in IA therapy, bind to intracellular glucocorticoid receptors in synoviocytes and chondrocytes, forming a receptor–ligand complex that translocates to the nucleus. This complex inhibits transcription factors, such as nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and activator protein 1 (AP-1), which drive proinflammatory gene expression. Consequently, cytokine synthesis, including interleukin-1 (IL-1), IL-6 and tumour necrosis factor-alpha (TNF-α), is suppressed, thereby reducing local inflammation.¹⁹ Corticosteroids typically provide significant pain relief within the first week of treatment across various joint types. However, this decreases to mild symptom relief by 3 months and returns to baseline pain levels by 6 months.^6,20,21 Current guidelines recommend limiting corticosteroid injections to no more than three to four times per year per joint to mitigate adverse effects.²² Long-term, repeated injections necessitate balancing therapeutic benefits, such as pain relief and improved joint function, against risks such as cartilage degeneration, infection, hypothalamic–pituitary–adrenal axis suppression, postinjection flare (chemical synovitis caused by steroid microcrystals), skin hypopigmentation and atrophy, particularly in superficial joints. Repeated injections may also be less effective over time, possibly because of cumulative degenerative effects on cartilage or desensitisation of inflammatory pathways.²³

Viscosupplements, such as HA, bind to CD44 and the receptor for hyaluronic acid-mediated motility (RHAMM) on synoviocytes and chondrocytes. This interaction reduces proinflammatory mediators, such as IL-1β and TNF-α, while enhancing synovial fluid's viscoelasticity, and thereby improving joint lubrication and shock absorption.²⁴ Two systematic reviews of IA HA injections were published in 2022. One included 38 studies with 5025 patients for knee OA, while a second review examined 16 studies with 587 patients for first CMCJ OA. Both reported pain reduction and functional improvement lasting up to 6 months.^25,26 Although generally well tolerated, variability across studies emphasises the need for standardised research to confirm these benefits.

Orthobiologics, such as PRP and MSCs, release growth factors including platelet-derived growth factor, transforming growth factor-beta and vascular endothelial growth factor, which facilitate cellular proliferation, extracellular matrix synthesis and angiogenesis.²⁴ Mesenchymal stem cells, commonly collected from bone marrow aspirates (BMAs) or adipose tissue, can differentiate into chondroblasts, supporting cartilage repair and regeneration.²⁴ Assessing the efficacy of orthobiologics is challenging because of variability in cell concentration, growth factor concentrations, injection protocols, the joint type and disease status. For example, a 2023 systematic review and meta-analysis of 24 RCTs involving 1344 patients found that PRP improved pain and function in knee and ankle OA, with benefits lasting up to 6 months in some studies and up to 12 months in others. Moreover, the analgesic effect of leucocyte-poor PRP was superior to leucocyte-rich formulations. However, PRP demonstrated limited efficacy in hip OA.²⁷ Similarly, a 2024 systematic review of BMA therapy in knee OA, encompassing 11 studies with 876 patients, reported improvements in pain and function, with benefits lasting up to 6 months in some studies and up to 24 months in others.²⁸

Prolotherapy, such as hyperosmolar dextrose solution (typically 10% or higher), creates osmotic stress that dehydrates local cells, inducing controlled inflammation. This process releases growth factors and cytokines, attracting immune cells and initiating a reparative response that promotes tissue repair and regeneration.²⁴

A 2017 systematic review of prolotherapy for knee, first CMCJ, and finger joint OA included seven RCTs with 393 participants and reported improvements in pain and function, with benefits ranging from less than 12 weeks to 12 months. However, variability in study designs and methodological quality highlighted the need for further research to confirm its efficacy.²⁹

Although the above injectables hold promise for managing joint diseases, current National Institute for Health and Care Excellence (NICE) guidelines discourage the routine use of HA, PRP, MSCs and prolotherapy because of insufficient evidence for consistent improvements in pain or function. In contrast, NICE recommends IA corticosteroid injections as part of a comprehensive management strategy, alongside rehabilitative therapy, to enhance pain relief and joint function.³⁰

Intra-articular injections

This section focuses on commonly injected joints in clinical practice, outlining technical principles broadly applicable to other joints. For each joint discussed, although multiple approaches are available, the selected techniques have been chosen for their simplicity and effectiveness.

Before performing IA injections, it is essential to obtain informed consent and assess for contraindications, including systemic or local infection, allergy to injectate components, periarticular fracture, joint prosthesis and unstable coagulopathy. Corticosteroid injections should also be avoided if joint replacement surgery is planned within the next 3 months, because of the increased risk of postoperative infection.²² These procedures should be conducted in a clinical setting equipped with resuscitation appropriate monitoring facilities. Ultrasound scanning before the procedure is critical for identifying neurovascular structures, planning optimal needle access to the joint and selecting suitable ultrasound probes while adjusting image settings. Marking the transducer position and needle entry points during the scanning phase increases accuracy and efficiency.

Injection technique

Patients should be positioned reclining—supine, semi-recumbent or lateral—to minimise the risk of vasovagal reactions and enhance comfort. Intra-articular injections must be performed aseptically, adhering to stringent infection control protocols, including the use of sterile ultrasound gel. A recent report from the UK Health Security Agency (UKHSA) highlighted a cluster of Burkholderia stabilis infections linked to non-sterile ultrasound gel products.³¹ The needle should be advanced under ultrasound guidance, targeting either the synovial recess or the joint space, preferably in-plane with the bevel facing the articular cartilage to prevent scraping the cartilage. Alternatively, an out-of-plane approach may be used depending on the joint and access route, while avoiding neurovascular and other critical structures. Proper needle placement within the joint can be confirmed by the ease of injection, the flow of injectate away from the needle tip in the joint, the absence of extra-articular extravasation and by visible distension of the joint capsule. Colour Doppler imaging may also be used to verify IA placement by displaying a colour signal during injection.

Injectate volume

The injectate volume is determined by factors such as joint size, the underlying condition and the type of injectate used. Typically, 0.5–1 ml is used for smaller joints, 1–5 ml for medium-sized joints and 5–10 ml for larger joints. These commonly used volumes are based primarily on clinical experience rather than robust scientific evidence. A gradual increase in resistance during injection, pain or discomfort or backflow into the syringe may indicate that the capsular volume limit has been reached. This can occur even with smaller volumes in conditions with reduced joint space, such as OA.²² Overstretching the joint capsule by using higher injection volumes is sometimes used deliberately, for example in shoulder joint hydrodilatation. The volume of fluid injected typically ranges 20–40 ml, though the exact volume varies among practitioners and is influenced by individual patient-related factors, such as tolerability to the procedure.⁷

Large joints

Glenohumeral joint

A comparative observational study evaluated the injection accuracy of the ultrasound-guided posterior approach and the anterior rotator cuff interval approach, using postinjection MRI to assess each technique. The study concluded that both approaches were effective and well tolerated. However, the posterior approach was deemed more advantageous because leakage of injectate was reduced and it was easier to perform compared with the rotator interval approach.³² For the posterior approach, the ultrasound transducer is positioned in an axial plane over the posterior glenohumeral joint, just below the scapular spine, with the humerus adducted across the thorax to enhance visualisation of the joint space. The needle is advanced in-plane from lateral to medial, targeting the posterior synovial recess above the humeral head to avoid damage to the labrum and minimise the risk of injury to neurovascular structures near the spinoglenoid notch (Fig. 1A).

Fig 1.

Large joints. The yellow arrow indicates the needle path into the joint space or synovial recess. (A) Left glenohumeral joint: humeral head (HH), glenoid (G), spinoglenoid notch (SPG), labrum (∗). (B) Left sacroiliac joint (SIJ): sacrum (S), second sacral foramina (SII), sacroiliac joint (SIJ). (C) Left hip joint, axial oblique approach: femoral head (FH), acetabulum (A), labrum (∗). (D) Left hip joint, sagittal oblique approach: femoral head (FH), acetabulum (A), labrum (∗). (E) Right hip joint, axial oblique approach: showing needle tip positioned in the anterior synovial recess above the femoral head (FH). (F) Right hip joint, sagittal oblique approach: showing distension of the capsule with local anaesthetic (LA), labrum (∗). (G) Right knee, mid-medial subpatellar approach: patella (P), medial femoral condyle (MFC). (H) Left knee, suprapatellar approach, sagittal view: patellar tendon (PT), suprapatellar synovial recess (SPR), femur (F), patella (P). (I) Left knee, suprapatellar approach, axial view: patellar tendon (PT), suprapatellar synovial recess (SPR), femur (F).

Sacroiliac joint

A 2022 systematic review of sacroiliac joint (SIJ) injection techniques, encompassing eight studies involving 420 patients, reported that CT guidance provides the highest accuracy for needle placement, followed by fluoroscopy, ultrasound and, lastly, landmark-guided injections, which were the least accurate. Despite these differences, pain and disability outcomes generally improve across imaging techniques, except with landmark-guided approaches.³³ For ultrasound-guided SIJ injections, the transducer is initially positioned in a parasagittal oblique orientation over the sacrum to identify the second sacral foramina (SII) on the targeted side. Once identified, the transducer is rotated to an axial orientation to visualise both the SII and the SIJ within the same image. The needle is then inserted in-plane from medial to lateral into the joint space (Fig. 1B). Careful aspiration and the use of colour Doppler during SIJ injections help avoid inadvertent intravascular needle placement.

Hip joint

The proximity of the hip joint to the femoral neurovascular bundle presents a potential risk, as inadvertent puncture has been reported with fluoroscopy-guided injections.³⁴ In contrast, ultrasound guidance allows direct visualisation of neurovascular structures, significantly reducing this risk. For example, in a retrospective review of 358 ultrasound-guided hip aspirations and injections, no instances of vascular or femoral nerve puncture were reported.³⁵ Two anterior approaches are commonly used for hip joint injections: the axial oblique and sagittal oblique approaches.³⁶ In the axial oblique approach, the transducer is positioned over the anterior hip joint in an axial oblique orientation, just below and parallel to the iliopubic eminence, to obtain a short-axis view of the femoral head and acetabular rim. The needle is then inserted in-plane, from lateral to medial, into the anterior synovial recess just above the femoral head (Fig. 1C). This approach is often preferred for patients with a larger body habitus because the distance to the joint is shorter. Alternatively, in the sagittal oblique approach, the transducer is aligned parallel to the femoral neck, with the needle inserted in-plane, from distal to proximal, into the anterior synovial recess at the junction of the femoral head and neck (Fig. 1D). This technique is particularly useful for assessing joint effusion. Both techniques require caution to avoid the labrum and lateral circumflex vessels. For medicolegal image archiving in diagnostic hip injections, the authors use the axial oblique approach for needle insertion and the sagittal oblique approach to confirm capsular distension with local anaesthetic (Fig. 1E and F).

Knee joint

Although landmark-guided injections remain in practice for the knee joint, ultrasound-guided techniques offer superior accuracy. For instance, a 2021 systematic review analysed 12 RCTs involving 1431 patients and 1315 knees, demonstrating that ultrasound-guided knee injections consistently achieved accuracy rates exceeding 95%. In contrast, blind injections exhibited variable accuracy, ranging from 77.3% to 95.7%.³⁷ Notably, two ultrasound-guided approaches had particularly high success rates: the mid-medial subpatellar approach, with a 97% accuracy rate using the in-plane technique and 95% with the out-of-plane approach, and the suprapatellar approach, which achieved a 100% accuracy rate.^38,39

For the suprapatellar approach, typically reserved for cases with joint effusion, the knee is positioned in mild flexion, which facilitates the accumulation of fluid in the suprapatellar synovial recess. The transducer is placed sagittally over the distal thigh, just superior to the upper pole of the patella, to visualise the synovial recess (Fig. 1G). To avoid puncturing the quadriceps tendon during needling, the transducer is rotated transversely and slid slightly laterally with gentle pressure to accentuate fluid in the lateral synovial recess. The needle is then advanced in-plane from lateral to medial (Fig. 1H). When joint effusion is absent, the mid-medial subpatellar approach may be more appropriate. In this approach, the transducer is positioned transversely over the medial compartment, and the needle is directed either in-plane or out-of-plane into the joint space between the patella and the medial femoral condyle (Fig. 1I).

Medium joints

Elbow joint

The elbow joint is formed by the articulation of the proximal radius, proximal ulna and distal humerus, enclosed within a single joint capsule. Among various injection techniques, the lateral radiocapitellar approach is generally preferred for its ease of access and anatomical remoteness from the ulnar nerve.⁴⁰ In this technique, the transducer is positioned over the lateral aspect of the radiocapitellar joint, aligned with the long axis of the radius, and the needle is advanced either in-plane or out-of-plane into the joint space (Fig. 2A).

Fig 2.

Medium and small joints. The yellow arrow indicates the needle path into the joint space or synovial recess. (A) Right lateral radiocapitellar joint: capitellum (C), radius (R). (B) Right distal radiocarpal joint: radius (R), scaphoid (SC). (C) Right acromioclavicular joint (ACJ): acromion (AC), clavicle (CL). (D) Right ACJ, sagittal view: joint disc (JD). (E) Right first carpometacarpal joint: trapezium (TZ), first metacarpal (M). (F) Right scaphotrapeziotrapezoid joint: scaphoid (SC), trapezium (TZ), first metacarpal (M). (G) Right tibiotalar joint: distal tibia (TIB), talar dome (TAL). (H) Right first metatarsophalangeal joint: first metatarsal (MT), proximal phalanx (PP).

Distal radiocarpal joint

The distal radiocarpal joint is frequently targeted in clinical practice, particularly for managing conditions such as OA and RA.⁴¹ To perform the injection, position the transducer dorsally along the long axis of the distal radius, and slide it distally until the joint space between the radius and scaphoid is seen. The needle is then inserted in-plane, from distal to proximal, into the joint space (Fig. 2B).

Tibiotalar joint

Injections into the tibiotalar joint are commonly performed by orthopaedic surgeons, particularly to differentiate between IA and extra-articular sources of ankle pain. A survey of American Orthopaedic Foot & Ankle Society members reported that 97% routinely perform tibiotalar joint injections.⁴² To perform the procedure, position the transducer in a sagittal orientation over the distal tibia and slide it distally until the joint space between the tibia and the talar dome is seen. The needle is then inserted in-plane, from distal to proximal into the joint space (Fig. 2C), with careful attention to avoid nearby neurovascular structures.

Small joints

Acromioclavicular joint

Studies have shown that ultrasound-guided injections achieve a 100% success rate compared with 40% for palpation-guided techniques.⁴³ To visualise the joint, position the transducer in an axial plane over the clavicle and slide it laterally until the joint space, typically appearing as a ‘V' shape, is identified (Fig. 2D). This approach supports both in-plane and out-of-plane needle insertion techniques. Precise needle placement is critical to avoid injecting into the subacromial bursa or the supraspinatus tendon located beneath the joint. Alternatively, the acromioclavicular joint can be visualised by positioning the transducer in a sagittal plane over the clavicle and sliding it laterally to locate the hypoechoic joint space (Fig. 2E), facilitating in-plane needle insertion.

First CMCJ and scaphotrapeziotrapezoid joint

These joints are common targets for injection in clinical practice, offering both diagnostic and therapeutic benefits, such as differentiating OA pain between these anatomically proximate joints.⁴⁴ For the CMCJ, position the ultrasound transducer along the dorsal aspect of the first metacarpal's long axis and slide it proximally to visualise the joint space between the first metacarpal and trapezium (Fig. 2F). Sliding further proximally reveals the scaphotrapeziotrapezoid joint space between the trapezium and scaphoid (Fig. 2G). Both joints can be injected using either an in-plane or out-of-plane approach. It is critical to identify and avoid the superficial branch of the radial artery, which lies in close proximity to these joints.

First metatarsophalangeal joint

The first metatarsophalangeal joint is the most common site of radiographic OA in the foot, with a prevalence of 42.8%, and symptomatic OA affecting 7.8% of adults aged ≥ 50 yrs.⁴⁵ It is also a common target for injection to provide pain relief. For injection, position the transducer in a sagittal plane over the dorsal aspect of the joint and advance the needle in-plane from proximal to distal into the joint space (Fig. 2H).

Conclusions

Ultrasound-guided IA injections offer a targeted approach for managing joint disorders by delivering therapeutic agents directly into the joint, reducing systemic adverse effects while increasing efficacy. Emerging advancements in precision medicine and orthobiologics are poised to revolutionise IA therapy.

MCQs

The associated MCQs (to support CME/CPD activity) will be accessible at www.bjaed.org/cme/home by subscribers to BJA Education.

Declaration of interests

The authors declare that they have no conflicts of interest.

Biographies

Major Tammar Al-Ani RAMS FRCA EDRA EDIC EDPM PGcert (MSK US-Injection Therapy) is a consultant anaesthetist and part-time post-CCT fellow in pain medicine at Glasgow Royal Infirmary.

Kenneth Lupton FRCR is a consultant musculoskeletal radiologist at Glasgow Royal Infirmary.

Matrix codes: 1A02, 2E03, 3E00.