Femur Fracture After Hip Replacement: Causes and Treatment

A femur fracture near a hip replacement implant, known as a periprosthetic femoral fracture, occurs in roughly 6 out of every 1,000 hip replacement patients over ten years, making it one of the more serious complications a person with a hip prosthesis can face. A large UK analysis of over 800,000 hip replacements found that about 0.6% of patients needed surgery specifically for this type of fracture, with an incidence rate just under one fracture per 1,000 implant-years of follow-up.¹ The numbers sound small, but when millions of people worldwide are living with hip replacements, the real-world burden is substantial. What makes this injury tricky is that its causes, treatment, and prognosis vary enormously depending on the type of fracture, the state of the bone, and whether the implant is still solidly fixed.

Why These Fractures Happen

The overwhelming cause is a fall. One study examining periprosthetic fractures after total hip replacement found that falls from standing height caused 94% of them.² That may seem unremarkable until you consider that a healthy femur typically withstands a standing-height fall without breaking. The reason it doesn’t hold up here is that the bone around an implant is already compromised, often by a combination of factors working together.

The most significant underlying factor is bone density. Osteoporosis and osteopenia weaken the femur to the point where it can crack around the metal stem of the prosthesis with relatively little force. That same study found the prevalence of a diagnosed bone-density problem jumped from about a quarter of patients before their fracture to 44% afterward, meaning many people had undiagnosed weak bones heading into the event.² Low bone mineral density is directly linked to a higher revision rate and a greater chance of periprosthetic fracture.³

Beyond bone quality, the implant itself plays a role. Uncemented stems, which rely on a tight press-fit into the bone, carry a higher risk of both intraoperative and postoperative fractures compared to cemented stems.⁴ A systematic review and meta-analysis comparing the two approaches found that cemented stems showed roughly half the fracture risk of uncemented stems, though the difference did not reach statistical significance because the available data were limited and varied widely.⁵ Even among cemented stems, design matters. Polished taper-slip stems, which are engineered to settle slightly into the cement over time, transmit sudden loads as hoop stresses directly to the surrounding bone, and registry data show they carry higher fracture rates than composite-beam cemented stems that bond more firmly to their cement mantle.⁴ Biomechanical testing in lab models confirms that certain polished taper-slip designs concentrate more stress at the critical failure point compared with other cemented stems.⁶

Cortical defects also deserve mention. If there is a thin spot, a screw hole from a previous surgery, or a small crack created during the original hip replacement, the bone is vulnerable right at that point. Long-stem femoral components have been suggested as a prophylactic measure when a cortical defect is present, because they bridge the weak spot and redistribute stress.⁷

How These Fractures Are Diagnosed

Pain after a fall is the obvious red flag, but not every periprosthetic fracture is obvious on a standard X-ray. Some fractures are occult, meaning they are too subtle for plain radiographs to catch, especially hairline cracks near a press-fit stem. When a periprosthetic fracture is suspected but X-rays look normal, a CT scan with metal artifact reduction software is the preferred first-line imaging tool. It provides detailed views of the bone around the metalwork without the distortion that metal implants usually cause on scans.⁸ MRI can also detect occult fractures with high accuracy, but CT is generally preferred for patients who already have a hip implant in place.⁹

The Vancouver Classification and Why It Matters for Treatment

Once a periprosthetic fracture is confirmed, surgeons classify it using the Vancouver system, which groups fractures by location and implant stability. The classification has been independently validated across multiple countries and by observers ranging from experienced consultants to medical students, with good agreement between readers.¹⁰ The reason this classification gets so much attention is that it directly determines the treatment plan. There are three main types:

Type A: Fractures around the very top of the femur, near the trochanters. These are often stable and may not need surgery.
Type B: Fractures around or just below the stem of the implant. This is the most common and consequential category, and it is further split into B1 (stem still well fixed), B2 (stem loose, bone quality adequate), and B3 (stem loose, bone quality poor).
Type C: Fractures well below the tip of the stem, essentially a standard femur fracture that happens to be in someone with a hip replacement.

The B subtypes drive the biggest treatment decisions. A B1 fracture with a stable implant calls for a very different operation than a B3 fracture where the stem is rattling loose in crumbling bone. Getting the subtype right is so important that some authors recommend surgeons open the hip during surgery and physically test whether the stem is truly fixed, because up to 20% of fractures that look like B1 on imaging turn out to have a loose stem once you get in there.¹¹ Misclassifying a loose stem as stable can lead to a fixation that fails because the underlying problem was never addressed.

Surgical Treatment by Fracture Type

For Type A fractures and undisplaced B1 fractures where the bone crack is inherently stable, non-operative management is sometimes possible. This involves protected weight-bearing and close monitoring with repeat imaging. A review of non-operatively managed fractures around uncemented stems confirmed that this approach can work when the fracture pattern, implant, and patient are carefully selected.¹² But the trend in recent years has been toward surgical fixation even in undisplaced cases, provided the patient can tolerate surgery, because it allows earlier mobilization and avoids the deconditioning that comes with prolonged bed rest in an older adult.¹³

For displaced B1 fractures, the standard approach is open reduction and internal fixation using locking plates, sometimes augmented with cables or wires wrapped around the bone and stem.¹⁴ Locking compression plates have become the workhorse for these injuries because they grip the bone with fixed-angle screws that do not rely on friction against the bone surface, an advantage in osteoporotic bone where conventional screws can pull out.¹⁵ Depending on the surgeon and fracture pattern, either a full open approach or a minimally invasive plating technique may be used.¹³

Vancouver B2 and B3 fractures, where the implant has loosened, typically require revision total hip replacement rather than simple fixation. The logic is straightforward: bolting a plate onto bone that surrounds a loose stem does not solve the looseness problem. In a revision, the old stem is removed and replaced with a longer one that bypasses the fracture site and gains fixation in healthy bone further down the femoral shaft.¹⁶ B3 fractures with severely deficient bone may also need structural bone grafts or metal augments to rebuild the femur enough to support a new implant.

Type C fractures, occurring below the stem tip, are treated more like a conventional femur fracture with plate fixation, though surgeons need to be careful that the plate extends far enough up the femur to overlap with the prosthesis zone.

Complication Rates After Repair

This is where the picture gets sobering. One analysis of 71 consecutive periprosthetic fracture cases found that 48% of patients experienced a complication, and a third required another operation, most often for re-fracture or failure of the fixation hardware.¹⁷ A separate series of 56 fractures achieved uneventful bone healing in the large majority, but still saw cases of nonunion with plate failure and later stem loosening requiring revision years down the line.¹⁸ Re-fracture after a new fall is a recurring theme in the literature, reflecting the ongoing vulnerability of osteoporotic bone around hardware.¹⁹

These complications are not just mechanical. Major systemic problems like blood clots, pneumonia, and cardiac events developed in about 23% of patients in one multicenter study, with another 12% suffering major local complications at the surgical site.²⁰

Mortality and Functional Outcomes

A periprosthetic femoral fracture carries real mortality risk, particularly in elderly or medically fragile patients. A meta-analysis pooling data from 35 studies and nearly 5,000 patients found that the pooled in-hospital death rate was about 2.4%, rising to roughly 3.3% within 30 days, about 5% within 90 days, and about 13% within one year.²¹ That meta-analysis noted that mortality in the first 30 days was comparable to what is seen after a standard hip fracture in someone who has never had a replacement, though one-year mortality was somewhat better. A Swedish registry study confirmed excess mortality compared with hip replacement patients who did not fracture, with the risk being most pronounced immediately after surgery and in patients under 70.²²

Certain patient characteristics sharply increase the risk. A multicenter study found one-year mortality of about 22%, with age 80 or older and a high burden of other medical conditions being the strongest predictors. Patients with significant comorbidities had roughly seven times the odds of dying within the first year compared with healthier patients.²⁰

For those who survive, functional recovery is often incomplete. More than half of patients in that same study did not regain their pre-fracture walking ability.²⁰ A study tracking patient-reported outcomes after periprosthetic fracture repair found significant declines in quality of life and hip function scores compared to how patients recalled feeling before the fracture. About 35% experienced a clinically meaningful decline in their Oxford Hip Score, and overall satisfaction was 62%.²³ In practical terms, this means many patients trade a well-functioning hip replacement for one that works noticeably less well after the fracture, even when the bone heals and the implant is stable.

Recovery and Rehabilitation

Rehabilitation after periprosthetic fracture repair follows the same broad principles as recovery from any major lower-limb fracture surgery, but with added complexity. The goals are restoring range of motion, rebuilding strength, and getting the patient walking again safely. Early mobilization matters for preventing the cascade of complications that come with immobility in older adults: blood clots, pressure sores, muscle wasting, and delirium. Physical therapy typically involves a team effort between surgeons and physiotherapists, with emphasis on gradually increasing weight-bearing, training balance and coordination, and addressing specific deficits related to the hardware and any changes in leg length or alignment.²⁴

Weight-bearing restrictions vary by fracture type and fixation method. A B1 fracture fixed with a sturdy locking plate may allow partial weight-bearing within a few days, while a B3 fracture treated with revision surgery and bone grafting may require weeks of restricted loading to let the graft incorporate. The timeline is individualized and depends heavily on what the surgeon saw during the operation regarding bone quality and fixation stability.

The Role of Osteoporosis Treatment in Prevention

Given that weak bone is the single biggest modifiable risk factor, treating osteoporosis after hip replacement is one of the clearest prevention strategies available. A study comparing patients who received osteoporosis treatment after hip replacement for a femoral neck fracture found that treated patients had a 10-year periprosthetic fracture rate of about 4%, versus roughly 6% in untreated patients. After adjusting for other variables, treated patients had about a third lower risk of sustaining a periprosthetic fracture.²⁵ Despite this evidence, osteoporosis remains dramatically undertreated in the hip replacement population. The jump from 24% to 44% diagnosed with a bone-density problem only after their periprosthetic fracture underscores how many people are walking around with fragile femurs that nobody has screened for or addressed.²

Fall prevention also matters, and for an older adult with a hip replacement, this means the usual toolkit: reviewing medications that cause dizziness, keeping the home free of trip hazards, maintaining lower-body strength through regular exercise, and managing vision problems. None of these interventions are specific to hip replacement patients, but the consequences of a fall are disproportionately severe when there is a metal stem running down the middle of the femur.

The Financial Burden

Periprosthetic femoral fractures are expensive to treat. A UK cost analysis found a median treatment cost of about £15,600 per patient, with ward stay, operating theater time, and hospital overheads driving most of the expense. The study also found that NHS reimbursement fell short of actual costs by a median of nearly £3,800 per case, meaning hospitals lost money on every patient.²⁶ Vancouver B2 and B3 fractures, which require revision surgery and longer hospital stays, are the most expensive to manage.²⁷ With the number of people living with hip replacements growing every year as populations age, the financial strain on healthcare systems is expected to increase, which adds urgency to prevention efforts like osteoporosis screening and implant selection strategies that may lower fracture risk in the first place.