Why Does My Hip Still Hurt After Hip Replacement?

Roughly one in four people who undergo total hip replacement still report some degree of hip pain months after surgery, a figure that surprises many patients who expected the operation to eliminate their discomfort entirely.¹ The causes range from straightforward mechanical problems with the implant to pain that has nothing to do with the hip joint itself. Sorting out which category you fall into is the essential first step toward getting relief.

How Common Is Persistent Pain, and How Bad Does It Get

The headline number of about 23% hides a wide range of experiences. In one prospective study that followed patients for six months, 58% recalled having at least some hip pain in the four weeks before their follow-up visit, but the majority of that pain was mild. Only about 17% of those reporting any pain had moderate-to-severe intensity.² A large nationwide questionnaire study from Denmark found a similar overall rate, with about 28% of patients reporting chronic pain on the operated side, and pain that limited daily activities to a moderate or worse degree in roughly 12%.³ In other words, most people who have lingering pain describe it as an annoyance rather than a crisis, but a meaningful minority are genuinely struggling.

Loosening and Infection

When a replaced hip hurts, surgeons first want to rule out two big structural problems: the implant loosening from the bone it sits in, and infection around the prosthesis. Together, these account for a substantial share of painful hip replacements. In a systematic review tallying the diagnoses behind persistent pain after hip arthroplasty, loosening or infection was found in nearly 29% of cases.⁴

Aseptic loosening happens when the bond between the implant and bone gradually breaks down without any infection present. Tiny wear particles shed by the bearing surfaces trigger an inflammatory reaction that eats away at bone over years. The pain tends to come on gradually and worsen with weight-bearing. X-rays can sometimes show a widening gap between the prosthesis and bone, though early loosening is easy to miss on plain films.

Infection is trickier because it does not always look dramatic. A deep infection around the prosthesis can smolder with nothing more than mild, persistent pain as the only symptom.⁵ Fever, redness, and draining wounds are the obvious signs people associate with infection, but low-grade periprosthetic joint infections often skip those red flags entirely. Blood markers like C-reactive protein and white-cell counts are helpful when elevated, yet nearly half of confirmed infections in one study showed normal levels on both tests.⁶ That is why aspiration of the joint fluid is often necessary to make the diagnosis.

Iliopsoas Impingement and Other Soft-Tissue Problems

Not all post-replacement pain traces back to the implant–bone interface. A common soft-tissue culprit is irritation of the iliopsoas tendon, the large hip flexor that runs across the front of the joint. When the edge of the acetabular cup (the socket component) sticks out even slightly beyond the rim of the pelvis, it can rub against this tendon with every step, producing a deep groin ache that may worsen with stair climbing or getting out of a car. The same irritation can come from retained cement, prominent screws, or other hardware near the front of the socket.⁷ In the systematic review of painful arthroplasties mentioned earlier, iliopsoas impingement accounted for about 21% of cases.⁴

A radiographic analysis of over 1,600 hips found that patients who developed iliopsoas tendinopathy had significantly more leg lengthening and were more likely to have an anteriorly prominent acetabular cup. Women and patients with higher body mass index were also at greater risk.⁸ The good news is that this problem often responds to conservative treatment. Guided steroid and anesthetic injections into the iliopsoas bursa provided adequate pain relief in the majority of patients in one study, cutting average pain scores by more than half, though about 30% of patients needed a second injection.⁹

Another soft-tissue issue is tearing of the abductor tendons on the side of the hip, sometimes described as a “rotator cuff tear of the hip.” The gluteus medius and minimus muscles anchor to the greater trochanter and are essential for stable walking. Damage to these tendons, whether from the surgical approach itself or from gradual degeneration, causes pain over the outer hip and a noticeable limp. Tendon disorders after hip replacement generally start with non-operative management, including physical therapy and injections, but cases that don’t respond may require surgery.¹⁰

When the Pain Is Actually Coming from Somewhere Else

One of the more frustrating scenarios is pain that feels like it is in the hip but originates in an entirely different structure. Referred pain from the lumbar spine was the most common extra-hip cause in the systematic review of painful replacements, accounting for nearly 15% of cases, with the broader category of causes outside the hip reaching about 16%.⁴ Nerves from the lower spine supply much of the hip and thigh area, so a bulging disc or spinal stenosis can easily produce what feels like hip pain. A prospective study found that pain radiating below the knee was the feature most closely linked to a preexisting spine disorder rather than a hip problem.¹¹

The sacroiliac joint, where the base of the spine meets the pelvis, is another sneaky source. Patients frequently develop sacroiliac pain after hip replacement, and imaging studies have shown significant abnormal motion in that joint among affected patients.¹² The connection makes mechanical sense: hip replacement changes the alignment and movement patterns of the pelvis, which can shift stress onto the sacroiliac joint. Older research found that nearly 30% of patients showed functional impairment of one sacroiliac joint after hip replacement, which may partly explain the gluteal and low-back pain some patients report.¹³ Irregularities in the sacroiliac joint have also been associated with lumbar scoliosis and spondylolisthesis, suggesting that patients who already have spinal issues may be more vulnerable.¹⁴

Nerve Injury and Neuropathic Pain

Nerve damage during or after surgery is uncommon but can produce a distinctive type of pain: burning, electric-shock sensations, numbness, or tingling that ordinary painkillers don’t touch. The sciatic, peroneal, and femoral nerves are the most commonly affected. Most injuries show up immediately after surgery, particularly those caused by traction on the leg, limb lengthening, or pressure from surgical instruments. Delayed cases tend to have a structural cause, such as a prominent screw or a hematoma pressing on the nerve.¹⁵ The peroneal branch of the sciatic nerve is especially vulnerable and can cause foot drop when damaged.¹⁶ Some nerve injuries recover on their own over months; others become permanent sources of neuropathic pain that need specialized treatment.

Central Sensitization and the Brain’s Role in Persistent Pain

Sometimes every scan looks fine, the implant is well-positioned, there is no infection, and the soft tissues appear healthy, yet the patient still hurts. One emerging explanation involves central sensitization, a state in which the nervous system becomes amplified, processing ordinary signals as painful even after the original problem (the arthritic hip) has been removed. Patients who had signs of central sensitization before their surgery were less likely to feel that they had “forgotten” their artificial joint afterward, reporting more pain during movement and lower satisfaction.¹⁷ Research into the brain chemistry behind this found that higher preoperative levels of a particular serotonin breakdown product in spinal fluid predicted worse pain control six months after surgery.¹⁸ In plain terms, some people’s pain-processing systems get stuck in a high-alert mode that doesn’t automatically reset once the damaged joint is replaced.

Psychological factors feed into this picture. Preoperative anxiety and depression are independently associated with worse postoperative pain out to at least two years, even after accounting for other variables.¹⁹ A systematic review confirmed the same pattern: patients with higher preoperative depression and anxiety scores reported more pain, poorer function, and more complications after surgery.²⁰ This does not mean the pain is imaginary. It means that the brain’s emotional and pain-processing circuits overlap heavily, and one can amplify the other. Addressing mood and anxiety before and after surgery is one of the most modifiable risk factors for persistent pain.

Metal Hypersensitivity and Adverse Reactions to Implant Materials

A small number of patients develop an allergic-type reaction to the metals in their implant, most often cobalt, chromium, or nickel. Symptoms include persistent joint pain and swelling, and some patients also develop skin rashes or eczema.²¹ These reactions are driven by tiny metal particles and ions released through normal wear. While uncommon, they can lead to serious consequences including aseptic loosening, formation of inflammatory masses called pseudotumors, and outright device failure.²² Metal-on-metal bearing designs, which were more popular in the 2000s, generated particularly high volumes of debris and prompted widespread surveillance programs. Differentiating a metal allergy from a low-grade infection can be difficult because both present with pain and elevated inflammatory markers around the joint.²³

Prosthetic Impingement and Heterotopic Ossification

Impingement happens when the ball and socket components of the replacement collide at the extremes of motion, causing a painful clunk or pinch. It can result from component positioning that doesn’t match the patient’s natural movement patterns.²⁴ Impingement is not just painful in itself; repeated contact can accelerate wear and contribute to loosening over time, creating a compounding problem.

Heterotopic ossification is a separate and somewhat bizarre phenomenon in which bone forms in the soft tissues around the joint after surgery. In most cases, these bone deposits are small and cause no symptoms at all. But when significant heterotopic bone develops, it can restrict range of motion, produce severe pain, and in extreme cases lock the hip almost entirely.²⁵ A short course of anti-inflammatory medication or a single dose of radiation right after surgery is sometimes used prophylactically in patients considered high risk.

How Surgeons Figure Out What Is Wrong

Diagnosing the source of pain after hip replacement is often harder than diagnosing the original arthritis. Standard X-rays are the starting point and can show obvious loosening, abnormal component position, or heterotopic bone. But when X-rays look normal, the workup expands. Blood tests for inflammation help screen for infection, though as noted earlier, normal results do not rule it out. Joint aspiration, in which a needle draws fluid from around the prosthesis, is the most reliable way to confirm or exclude infection. When performed under ultrasound guidance in an orthopedic clinic, aspiration has an accuracy of about 87%, with a high negative predictive value, meaning a clean aspiration provides strong reassurance.²⁶

Advanced imaging can help with soft-tissue diagnoses. Metal artifact reduction MRI sequences allow visualization of tissues around a metal implant and are far better than CT at detecting pseudotumors and muscle wasting. In one study comparing MRI and CT for metal-on-metal hip surveillance, CT found pseudotumors in only 11 of 50 painful hips, while MRI found them in 25. CT performed better for detecting bone loss around the implant but was unreliable for soft-tissue assessment.²⁷ If infection remains suspected despite normal blood markers, combining erythrocyte sedimentation rate, C-reactive protein, and synovial fluid analysis yields the highest combined accuracy for identifying periprosthetic infection.²⁸

Does the Surgical Approach Matter

The route a surgeon takes to reach the hip joint can influence what kind of pain you experience afterward. The two most common approaches are the direct anterior approach, which works through a gap between muscles at the front of the hip, and the posterior or posterolateral approach, which cuts through the gluteal muscles at the back. A systematic umbrella review of randomized trials found that the anterior approach is associated with favorable early outcomes partly because it avoids cutting through major muscle groups.²⁹

In a large comparison, patients who had the direct anterior approach reported less moderate-to-severe trochanteric pain (about 14% versus 21%) and less groin pain (19% versus 24%) compared with posterolateral patients.³⁰ A prospective cohort study found that the abductor muscles, which are split or detached during a direct lateral approach, act as a pain generator in the early postoperative period.³¹ These differences tend to narrow over the first year, so the surgical approach matters most in the early months. If your pain is predominantly on the outer side of the hip, knowing which approach was used helps your surgeon interpret it.

When the Cause Stays Unknown

Even after a thorough workup, the painful diagnosis sometimes remains elusive. In the systematic review cataloging causes of persistent pain after hip arthroplasty, about 9% of cases had no identifiable source.⁴ Greater trochanteric pain syndrome, a catch-all diagnosis covering bursitis and tendon irritation around the outer hip, accounted for another 13% and is sometimes considered a diagnosis of exclusion when more specific causes cannot be pinpointed. For patients whose pain seems disproportionate to any identifiable structural problem, central sensitization and psychological factors become increasingly relevant explanations. In these situations, a multidisciplinary pain management approach, combining targeted physical therapy, pharmacological treatment for nerve-related pain, and psychological support, tends to produce better results than continued imaging and repeated injections chasing a structural diagnosis that may not exist.