Treatment for Iliopsoas Tendonitis After Hip Replacement

Treatment for iliopsoas tendonitis after hip replacement follows a stepwise approach, starting with conservative measures like anti-inflammatory medications, physical therapy, and guided corticosteroid injections, then escalating to surgical options if pain persists. A recent meta-analysis found that over half of patients managed conservatively still had symptoms, compared with roughly 18% after iliopsoas tenotomy and 13% after acetabular cup revision, which gives a clear picture of how outcomes shift across the treatment ladder. The condition itself, a persistent groin pain caused by the iliopsoas tendon rubbing against the new hip implant, is uncommon but increasingly recognized as surgeons and patients become more aware of it.

Why the Iliopsoas Gets Irritated After Hip Replacement

The iliopsoas is a deep muscle-tendon unit that runs from the lower spine across the front of the hip joint and attaches to the upper thighbone. After a total hip replacement, the metal or ceramic acetabular cup sitting in the hip socket can protrude slightly beyond the native bone rim. When the iliopsoas tendon slides over that protruding edge with every step, it gets chronically irritated. The result is groin pain that can start weeks or months after surgery, often catching people off guard because the hip replacement itself went smoothly.

Acetabular overhang is the single biggest mechanical driver. One study found that any measurable overhang raised the odds of iliopsoas impingement roughly sevenfold, while a cup-to-native-femoral-head diameter ratio above 1.1 nearly quadrupled the risk. Female patients faced about three times the risk compared with males, likely because of anatomical differences in pelvic shape and tendon path.¹ CT imaging has helped quantify the problem further: patients whose symptoms did not respond to initial treatment tended to have greater cup overhang in both the axial and sagittal planes, and a threshold of about 10 mm of axial overhang reliably predicted a higher chance that even tenotomy would fail.²

Getting the Diagnosis Right

Groin pain after hip replacement has many possible causes, including loosening of the acetabular component, stress fractures, and infection, so confirming that the iliopsoas is the culprit matters before committing to any treatment plan.³ The good news is that a careful physical exam can be surprisingly accurate. Testing seated hip flexion strength on the affected side showed about 96% sensitivity and a positive predictive value around 77%, and tenderness when pressing directly on the iliopsoas tendon reached about 93% sensitivity.⁴ In a separate study, the hip extension contracture (HEC) test performed even better, with 94% sensitivity and 88% specificity.⁵

MRI, surprisingly, is not the go-to screening tool here. Among patients who had MRI scans, only about 18% showed visible abnormalities, giving the test a sensitivity of just 19%. Its specificity was high at 85%, so a positive MRI finding is meaningful, but a normal MRI does not rule out the problem.⁶ Ultrasound can be more helpful because it lets clinicians see the cup’s anterior edge and check for direct contact between the implant and the tendon. When iliopsoas bursitis was visible on ultrasound, it was 100% specific for impingement, and a sagittal cup measurement greater than 5 mm at the level of the tendon had both sensitivity and specificity above 80%.⁷

One additional diagnostic step that experienced surgeons emphasize is a confirmatory injection. Infiltrating the iliopsoas bursa with local anesthetic under imaging guidance can confirm the tendon as the pain source before anyone commits to surgery. A systematic review of arthroscopic tenotomies concluded that performing a diagnostic infiltration test beforehand helps prevent surgical failure.⁸

Conservative Treatment as the First Step

The standard initial treatment plan includes anti-inflammatory medications, activity modification, and physical therapy focused on gentle hip flexor stretching and core stabilization.⁹ Physical therapy aims to reduce the mechanical load on the iliopsoas by improving surrounding muscle balance, but the evidence for conservative management alone is sobering. In one radiographic study of over 1,600 hips, only about 36% of patients managed without surgery reported improvement in their groin pain, compared with complete relief in all patients who went on to arthroscopic tenotomy.¹⁰ A meta-analysis found that persistent symptoms remained in about 54% of conservatively managed patients, with around 16% eventually needing surgery anyway.¹¹

That said, conservative treatment still makes sense as the opening move. Some patients do get lasting relief, the risk is essentially zero, and it buys time to confirm the diagnosis while you see whether the irritation settles as tissues adapt to the implant. The key is not to leave someone in limbo for too long if it clearly is not working.

Guided Injections

Corticosteroid injections into or around the iliopsoas bursa, performed under ultrasound or fluoroscopic guidance, occupy an important middle ground between oral medications and surgery. They serve a dual purpose: therapeutic relief and diagnostic confirmation. If a patient’s groin pain disappears immediately after the injection, that strongly points to the iliopsoas as the source.

In one study, ultrasound-guided injections resolved groin pain in about 79% of patients after hip replacement, though patients without acetabular cup overhang had higher success rates.¹² Another series found that average pain scores dropped from about 6.4 to 2.9 after injection, but roughly 30% of patients needed a second injection within about eight months, and 22% ultimately required surgery to address the underlying cause.¹³ Sonography-guided peritendinous injections have also been confirmed as useful both diagnostically and therapeutically, providing relief to most patients with iliopsoas irritation after hip replacement.¹⁴

Platelet-rich plasma (PRP) injections have been explored as an alternative, but the evidence is thin. A small phase 1 study of just three patients found the procedure was safe but only one patient experienced near-complete symptom resolution, while two continued to have groin pain.¹⁵ PRP for this specific indication is still very much experimental.

Iliopsoas Tenotomy and Lengthening

When conservative measures and injections fail, the next step is usually a surgical release of the iliopsoas tendon. This can be done arthroscopically (using a camera and instruments through small incisions near the hip) or endoscopically, and involves either cutting through the tendon (tenotomy) or making controlled partial cuts to lengthen it (fractional lengthening). Both approaches aim to eliminate the mechanical friction against the cup.

A systematic review covering 431 patients across 16 studies found that both arthroscopic and endoscopic techniques produced favorable outcomes, with arthroscopic tenotomy showing slightly higher success rates.¹⁶ In a series of 13 patients treated arthroscopically, hip scores and muscle strength scales improved significantly after about 10 months, with no complications.¹⁷ Another study following 15 hips for a median of nearly four years reported 80% of patients were pain-free at their latest follow-up, with median pain scores dropping from 8 out of 10 before surgery to 0 afterward.¹⁸

The meta-analysis comparing all three management approaches found that persistent symptoms after tenotomy were around 18%, with only about 5% needing further surgery. The complication rate was low at roughly 2%.¹⁹ Not every patient achieves complete relief, though. One 12-month follow-up study found about 45% had complete relief, 31% had significant improvement, and 24% had no improvement. That study also flagged hip instability as something surgeons need to watch for after the procedure.²⁰

Where to Cut Matters

Surgeons can release the iliopsoas tendon at two different levels: at the acetabular rim (where the tendon rubs against the cup) or lower down at the lesser trochanter (a bony bump on the upper femur where the tendon inserts). There is an ongoing debate about which location produces better results.

A comparative study found that patients who had the release at the lesser trochanter tended to recover more hip flexion strength, with about 71% regaining normal strength compared with 42% in the acetabular rim group. Functional scores also trended higher in the lesser trochanter group, though the difference did not quite reach statistical significance in this relatively small study.²¹ The reasoning is that cutting at the lesser trochanter preserves more of the muscular portion of the iliopsoas, which helps maintain strength. Neither technique showed complications in this series.

When the Cup Itself Needs to Be Revised

If the acetabular component is significantly malpositioned or has substantial overhang, and tenotomy alone does not solve the problem, surgeons may recommend revising the cup itself. This is a bigger operation with more risk, so it is typically reserved for cases where the implant position is clearly the root cause.

A study of 55 acetabular revisions for iliopsoas impingement found strong functional improvement, with the Oxford Hip Score improving by a median of 18 points and 87% of patients achieving what clinicians consider a meaningful clinical difference. About 73% were satisfied or very satisfied. However, the complication rate requiring further surgery was around 11%, much higher than the roughly 2% seen with tenotomy alone.²² The meta-analysis echoed this pattern: revision surgery produced the lowest rate of persistent symptoms at about 13% and the lowest rate of needing additional surgery at about 4%, but carried a complication rate of nearly 16%.²³

A systematic review comparing all three management strategies found that Harris Hip Scores improved across the board: from about 65 to 79 with conservative treatment, 55 to 83 with tenotomy, and 56 to 82 with revision. Patients who had revision surgery also showed higher Oxford Hip Scores and lower pain scores than the other groups, but given the higher complication risk, revision is generally offered only when the cup position is clearly contributing to the problem or when tenotomy has already failed.²⁴

The Trade-Off You Should Know About: Hip Flexor Weakness

One thing that often gets glossed over in discussions of tenotomy is what happens to hip flexor strength afterward. Cutting or lengthening the iliopsoas tendon relieves pain, but the iliopsoas is your primary hip flexor, and the muscle does not bounce back to full power.

A study measuring outcomes after endoscopic tenotomy found that hip flexor strength on the operated side was reduced by about 32% compared with the other side. Despite this measurable deficit, patients were still satisfied and said they would choose surgery again.²⁵ Research using MRI to track muscle changes after arthroscopic release confirmed the structural basis: the iliopsoas muscle on the surgical side was about 25% smaller than its counterpart, and seated hip flexion strength dropped by roughly 19%. Interestingly, supine hip flexion strength showed no significant difference between limbs, likely because other muscles like the rectus femoris can compensate when you are lying down.²⁶

For most people, this strength loss is a worthwhile trade for eliminating persistent groin pain. But it helps to go in with realistic expectations, particularly if you are active or need strong hip flexion for activities like climbing stairs, getting out of low chairs, or sports. Rehabilitation after tenotomy should include targeted strengthening of the surrounding hip flexors to partially compensate.

Functional Recovery After Tenotomy

Recovery data at two years or more paint a mixed picture functionally. In one series with minimum two-year follow-up, patients showed significant improvement in pain scores and in their ability to perform daily activities and sports, but the improvements in some areas, like participation in physical activity, did not reach statistical significance.²⁷ This pattern, good pain relief with incomplete functional restoration, is consistent across much of the literature. Patients tend to be happy because the groin pain that was ruining their quality of life is gone, but objective hip flexion power does not fully return. Rehabilitation protocols typically begin with gentle range-of-motion exercises and progress to resistance training over several months, though there is no widely standardized protocol for this specific procedure.

How Acetabular Cup Overhang Changes the Calculus

The amount of cup overhang does not just predict who develops iliopsoas tendonitis; it also influences which treatment is likely to work. Patients without significant overhang tend to do well with injections and may respond to conservative management or tenotomy alone. When overhang is substantial, the mechanical irritation is ongoing regardless of what you do to the tendon, which is why injection success rates are higher in patients without overhang.²⁸

CT scanning can quantify overhang and help guide treatment decisions. The finding that 10 mm of axial overhang predicts tenotomy failure is clinically useful: if imaging shows overhang beyond that threshold, the surgeon and patient may want to discuss cup revision rather than going through a tenotomy that has a high chance of not working.²⁹ Among tenotomy patients in that study, 38% of those who did not improve had significantly greater axial overhang than those who did. In practice, this means the treatment decision is not purely about how bad the symptoms are but about the underlying geometry of the implant.

Preventing Iliopsoas Tendonitis During the Original Surgery

Since acetabular overhang is the dominant risk factor, prevention largely comes down to implant positioning during the original hip replacement. Surgeons aim to seat the cup flush with or slightly recessed relative to the native acetabular rim, and to size the cup appropriately. A cup-to-native-femoral-head ratio above 1.1 nearly quadrupled the risk in one study, suggesting that upsizing the acetabular component even modestly can be enough to set up the problem.³⁰

Intraoperative imaging and navigation systems can help confirm cup position in real time, though not every surgical center uses them routinely. For patients at higher baseline risk, such as women or those with smaller native femoral heads, paying extra attention to cup sizing and anterior overhang during planning may prevent a frustrating postoperative complication. None of this guarantees prevention, but reducing anterior overhang is the most controllable factor surgeons have.