Where do injections fit in my hip or knee plan

Ongoing hip or knee pain that has not settled after a spell of exercise-based physiotherapy, activity changes and simple pain relief is often the point when an injection starts to feel like the “next step”. In practice, injections usually sit between day‑to‑day self‑management (strengthening, weight management where relevant, pacing) and more invasive options, and they are often used to reduce symptoms enough to keep walking, working or sleeping while longer-term plans are made.

An ultrasound-guided joint injection is an outpatient appointment where a clinician uses an ultrasound scanner to place a needle accurately into the joint space (or occasionally around irritated soft tissues), then injects a treatment such as platelet-rich plasma (PRP), corticosteroid (cortisone) or hyaluronic acid. The aim is symptom control and improved function; it is not an operation.

PRP is made from a person’s own blood. In published hip and knee osteoarthritis studies, PRP is generally reported as having mild, short‑lived side effects, but there is major variation in PRP preparation and injection schedules, which makes results harder to compare across clinics and trials. Evidence is more established in knee osteoarthritis than hip, where the randomised trial evidence base is smaller and longer‑term data remain limited.[1,2]

Corticosteroid injections are anti-inflammatory and are often considered for a painful flare or when inflammation is a major driver of symptoms, but they are not usually framed as a long-term maintenance strategy. In a 14‑year population-based cohort study (2010–2023; 404,797 adults), serious 30‑day complications such as infection-related or vascular hospitalisations were rare after intra‑ or peri‑articular injections, with overall comorbidity burden—rather than diabetes alone—most linked to risk.[3]

Injections can buy time, improve function, or sometimes help clarify a diagnosis, but they do not reverse advanced arthritis and some people still progress to surgery. Practical “find a specialist” resources are grouped once at the end of the guide rather than repeated after every section.

What to expect from ultrasound-guided PRP for hip pain

A hip PRP appointment is usually a single outpatient visit that combines a blood test-style draw with an image-guided injection into the joint. Blood is taken (often from an arm vein), then processed in a centrifuge to separate out the platelet‑rich portion. The clinician then cleans the skin over the front or side of the hip, applies ultrasound gel, and uses the ultrasound probe to watch the needle track into the hip joint before injecting the PRP. Local anaesthetic is commonly used, and the main sensation tends to be brief pressure or deep ache rather than a long procedure.

Ultrasound guidance matters more in the hip than in many other joints because the hip joint sits deep under layers of muscle and soft tissue. In the research setting, key hip PRP trials have used ultrasound-guided placement to confirm the injection is intra‑articular.[4,5]

Evidence in hip osteoarthritis (OA) is still developing, but there are a few practical takeaways from the better‑known trials. In a randomised clinical trial of 105 people with grade 2–3 hip OA, participants received two ultrasound-guided injections 2 weeks apart: PRP alone, hyaluronic acid (HA) alone, or PRP combined with HA. All three groups improved on pain and function scores at 2 months and 6 months, but at 6 months the PRP and PRP+HA groups had better function/disability outcomes than HA alone, and no serious adverse events were reported.[4]

Looking across the broader hip OA literature, a 2024 systematic review that pooled five randomised trials concluded that PRP appears safe and effective for symptom relief when compared with standard options such as HA. The same review highlighted a key limitation for clinic-to-clinic comparisons: PRP preparation methods and injection schedules varied substantially between studies, and outcomes beyond 12 months were not well defined.[1]

Not all PRP products or patient groups appear to respond in the same way. A 100‑patient comparative study that used three weekly ultrasound-guided injections found only limited overall improvement with either autologous PRP or umbilical cord-derived PRP. In that study, more sustained improvement at 12 months was mainly seen in people with milder radiographic disease receiving umbilical cord PRP, again without major safety signals.[5]

Overall, published hip PRP studies suggest a pattern of noticeable symptom improvement for many patients that can last 2–6 months, with a signal that less advanced OA may do better than more severe disease. The realistic aim is often reduced pain and better day‑to‑day function, rather than a dramatic, permanent change from a single injection course.[1,4,5]

How hip PRP evidence compares with knee PRP

For PRP, the knee is the best‑studied joint, which is why it tends to feel like the “standard” place to use it. In a 2025 meta‑analysis pooling 18 randomised controlled trials (1,995 patients) in knee osteoarthritis, PRP produced statistically and clinically meaningful improvements in pain (VAS) and function (WOMAC) versus placebo across follow‑ups from 1 to 12 months, with benefits often exceeding commonly used minimal clinically important difference thresholds.[2]

One reason the knee evidence has matured is that some studies report “how strong” the PRP is, not just that PRP was used. A systematic review of 29 knee OA RCTs that documented platelet dose found that trials reporting benefit at 6–12 months used roughly double the platelet dose (about 5.5×10^9 platelets) compared with trials without clear benefit (about 2.3×10^9).[6]

Protocol details are one reason knee results can differ between studies; the comparison treatment is another. Across randomised trials comparing PRP with corticosteroid injections for knee OA, both options generally reduce pain with favourable short‑term safety, and some studies suggest PRP’s benefits may last longer. However, findings are mixed and do not show that PRP is reliably superior to steroid injections for every knee OA patient or scenario.[7]

Hip PRP sits in a different evidence position. A 2024 systematic review identified only five randomised trials in hip OA (typically 43–111 participants each) and concluded PRP appears safe and effective versus comparators such as hyaluronic acid, but emphasised substantial variation in PRP preparation, injection schedules, and outcome measures, with limited long‑term data beyond 12 months.[1] Taken together, this means hip PRP is not necessarily ineffective—rather, certainty about durability, ideal protocol, and whether it alters the timing of hip replacement is lower than in the knee literature.[1,2]

Questions to ask about an ultrasound-guided PRP service

Practical differences between PRP services often sit in the “how” rather than the label on the leaflet, so a short set of process questions can reveal whether a clinic is set up to deliver (and evaluate) PRP properly.

1) Image guidance and operator experience (especially for the hip)

Published hip PRP studies generally use ultrasound guidance for intra‑articular placement in the deep hip joint.[4,5] Useful questions for a hip PRP provider include:

• Will the injection be ultrasound‑guided from needle entry to final placement, or is ultrasound used only to “check the area”?[4,5]
• Who operates the ultrasound scanner (the injecting clinician or an assistant), and how often are hip joint injections performed in a typical month?
• What steps are taken if the view is difficult on the day (for example, body habitus or osteophytes)?

2) What exactly is being injected?

Because PRP protocols vary across trials and clinics, clearer answers usually include specifics rather than “standard PRP”.[1]

• Is the PRP autologous (prepared from the patient’s own blood) and prepared in‑clinic on the same day?
• How many injections are recommended in a course, what spacing is used, and what would make the clinician change that plan?

3) Suitability: what problem is PRP meant to help in this joint?

A clinic’s answer should link PRP to a diagnosis and severity on imaging rather than offering one template for everyone.

• Which findings on imaging would make PRP more (or less) likely to help—such as earlier vs more advanced osteoarthritis?[1,5]
• In which scenarios would the clinician favour another injection option (for example, hyaluronic acid) instead?[1]

4) Defining “success”, and what happens if it does not help

Given that hip RCT follow‑up is often limited and protocols differ, a good service usually sets a review point and a back‑up plan.[1]

• Which measures will be recorded before and after treatment (for example VAS pain, WOMAC, hip function scores), and at what time points (for example 6 months and 12 months)?[1,4]
• What is the planned next step if there is little or no improvement after the first course?
• Statements such as “permanent cure” or “guaranteed cartilage regrowth” are usually a warning sign that limitations are not being discussed.

5) Side effects and how they are handled

Across hip PRP trials and reviews, adverse effects are generally described as mild and transient, but the clinic should still explain how flare‑ups and rare complications are managed.[1,4]

• What short‑term reactions are most common in the clinic and what contact route exists if pain escalates?

Search MSK lists specialists across the UK who offer PRP and other ultrasound‑guided injections; filters by region and specialty can help narrow options to clinicians who routinely treat hip or knee osteoarthritis.

When a corticosteroid injection makes sense and when it may not

Steroid (corticosteroid) injections are often considered when pain is severe enough to disrupt sleep, when a sudden flare is blocking day‑to‑day function, or when a clinician needs to clarify how much pain is coming from inflammation inside a joint rather than (for example) the surrounding muscles. In UK practice these are commonly done as an outpatient, image‑guided injection so the medication is placed accurately in the intended space.

The key trade‑off is speed versus durability. Corticosteroids are powerful anti‑inflammatories, so they can be useful for short‑term symptom control, but they are not usually framed as a treatment that changes the underlying course of osteoarthritis. This is one reason many clinicians avoid using them as a frequent, long‑term “maintenance” approach, and why repeat dosing tends to be conservative.

In tendon-related problems, clinicians are often more cautious with steroid use—particularly if there is concern about tendon health—so the target and diagnosis matter (for example, “in the joint” versus “into/around a tendon”).

Finally, serious systemic complications appear uncommon, but overall health still shapes risk. In a 14‑year population‑based cohort of 404,797 adults receiving intra‑ or peri‑articular corticosteroid (or hyaluronic acid) injections between 2010 and 2023, 30‑day hospitalisations for systemic or musculoskeletal infection and acute vascular events were rare and did not rise over time; the main independent predictor was overall comorbidity burden (Charlson Comorbidity Index), rather than diabetes status alone. That pattern supports a cautious, individualised approach where a clinician weighs the joint problem alongside the wider medical picture before recommending a steroid injection.[3]

Safer steroid use and how to choose a cautious provider

Judicious steroid use tends to be defined by clear “guardrails” and clear “stop rules”, rather than by how quickly an injection can be arranged. The emphasis here is on the practical checks that sit on top of the medical pros-and-cons already described: how often is “too often”, what counts as an adequate response, and what a cautious injection practice typically documents.

Rules of thumb that cautious clinicians often follow

In many services, repeat steroid injections into the same joint are spaced out and used sparingly, with decisions guided by the response to the last injection and the person’s overall risk profile.

Response also matters: if a well‑targeted injection does not produce meaningful relief, repeating the same approach over and over is usually hard to justify. In many clinics, this becomes a written “stop rule” that triggers a change of plan (for example, reassessing the diagnosis, imaging, rehabilitation focus, or an alternative injection type).

Green flags (and the questions that uncover them)

Answers that sound cautious usually include a clear interval for repeat injections, a definition of “success”, and a reason to stop. Useful screening questions for any clinic offering steroid injections include:

• “What is the shortest interval you use for repeat injections in the same joint, and what factors would make you extend that interval?”
• “After one injection, what result would count as a good response — and after two, what result would make further steroid injections unlikely?”
• “How is accurate placement checked — for example, is ultrasound used for needle placement when the target is deep or when anatomy is complex?”

Red flags that suggest overuse or poor risk control

Patterns that may indicate a less careful approach include offering frequent “top‑ups” without documenting the last response, or presenting steroid injections as a long‑term “maintenance” plan.

Overall health should also be part of the risk conversation. In a large cohort study, short‑term serious complications were rare after intra‑ or peri‑articular injections, and overall comorbidity burden was the main predictor of hospitalisation risk.[3]

Bringing the choice back to PRP vs steroid: steroids are usually framed around rapid control of an inflammatory flare or diagnostic clarification, while PRP is usually positioned as a longer‑horizon symptom and function strategy with more protocol variability. When comparing providers, the decisive difference is often whether the clinic can clearly explain when it would not repeat a steroid injection, and what it would do instead.