Nationwide Retrospective Cohort Study · Trauma

The epidemiology and outcomes of periprosthetic femur fractures

The Scottish National Audit of Periprosthetic Femur Fractures (SNAP Femur) Study

Kennedy MJ, Clement ND, Farrow L, Kennedy IW, Harding T, SCOTnet SNAP Femur Group, Blacklock C, Penfold RS, Clarke JV, Duckworth AD, MacLullich AMJ, Walmsley PJ, Hall AJ

Bone Joint J 2026;108-B(5):707–715 · doi:10.1302/0301-620X.108B5.BJJ-2025-0979.R1

328

Periprosthetic Femur Fractures

Scottish Centres

20.8%

One-Year Mortality

SMR 2.74

Standardised Mortality Ratio

Page 1 · As Published Open Access $The epidemiology and outcomes of periprosthetic femur fractures, as published in The Bone & Joint Journal$

British Editorial Society of Bone & Joint Surgery

SNAP Femur was published as a Trauma article in The Bone & Joint Journal, the flagship journal of the British Editorial Society of Bone & Joint Surgery. The article is published Open Access and is freely available to read and download in full.

Journal Bone Joint J

Publisher British Editorial Society

Article Type Trauma

Access Open Access

Read on boneandjoint.org.uk Download PDF

Abstract

Objective

Periprosthetic femur fracture (PFF) data capture in national registries is recognised to be limited. The aim of this study was to use hospital level data to establish patient characteristics, describe PFF management and mortality (including standardised mortality rate (SMR)), and compare outcomes to native hip fractures (NHF) using Scottish Hip Fracture Audit (SHFA) data.

Design

Nationwide retrospective cohort study of all patients aged ≥50 years sustaining a PFF managed in 16 centres between 1 January and 31 December 2019. Independent associations of PFF and mortality were evaluated with Cox regression survival analysis adjusted for confounders.

Setting

NHS Scotland. Data collected by the Scottish Collaborative Orthopaedic Trainee Research Network (SCOTnet).

Results

There were 328 PFFs (mean age 79.6 years (SD 10), 66% female). Compared with NHF, PFF patients were less frail (median Clinical Frailty Scale (CFS) 4 (IQR 3 to 5) vs 5 (IQR 4 to 6); p < 0.001) and more likely to be home-dwelling (91% vs 76%; p < 0.001). The majority were managed surgically (85%): 175 with fixation (53%), 99 with revision arthroplasty (30%), and 50 conservatively (15%). The one-year mortality rate and SMR were 20.8% (95% CI 16.2 to 25.0) and 2.74 (95% CI 2.10 to 3.40), compared with 29% and 3.66 in NHFs. Factors independently associated with increased mortality risk were interprosthetic fractures (aHR 2.65, 95% CI 1.41 to 5.00; p = 0.003), male sex (aHR 1.76, 95% CI 1.11 to 2.78; p = 0.015), older age (per year aHR 1.07; p < 0.001), and higher pre-injury frailty (CFS 5 to 9: aHR 4.16, 95% CI 1.18 to 14.7; p = 0.027). Time to theatre and management strategy were not independently associated with increased mortality.

Conclusion

PFFs are associated with an increased mortality risk and result in functional decline. Coding limitations mean most PFFs are likely missed in arthroplasty registries, underestimating the true incidence. National registry integration and tailored multidisciplinary pathways, similar to those for NHF, are essential for improving outcomes and healthcare planning.

View paper (Open Access)

Key Results

Principal findings

20.8%

One-year mortality rate

95% CI 16.2 to 25.0; compared with 29% for native hip fracture (p = 0.002)

SMR 2.74

Standardised mortality ratio

95% CI 2.10 to 3.40; approximately three times the expected mortality for age- and sex-matched population

5.2%

30-day mortality rate

95% CI 2.8 to 7.6; rising to 32.9% at median follow-up of 2.8 years

85%

Managed surgically

53% fixation, 30% revision arthroplasty, 15% conservative management

93.5%

Related to arthroplasty implants

228 around a hip implant (70%), 79 around a knee implant (24%)

>70%

Likely missed by arthroplasty registries

Due to coding limitations; SAP captures only arthroplasty-managed cases, underestimating incidence by up to 70%

Cox Regression Multivariable Analysis

Independent predictors of mortality

×4.16
High pre-injury frailty (CFS 5 to 9)
aHR 4.16 (95% CI 1.18 to 14.7) · p = 0.027

×2.65
Interprosthetic fracture (UCS Type D)
aHR 2.65 (95% CI 1.41 to 5.00) · p = 0.003

×1.76

Male sex

aHR 1.76 (95% CI 1.11 to 2.78) · p = 0.015

×1.07

Older age (per year increase)

aHR 1.07 (95% CI 1.04 to 1.11) · p < 0.001

Time to theatre and management strategy were not independently associated with mortality after adjustment for confounders.

Comparative Analysis

PFF vs native hip fracture (SHFA 2019 data)

Variable	PFF (SNAP Femur)	NHF (SHFA 2019)	p-value
N	328	7,130	—
Mean age, yrs (SD)	79.6 (10.1)	80.3 (10.0)	0.213
Female, %	66.2%	68.8%	0.339
Own home / sheltered housing	91%	76.4%	<0.001
ASA grade I or II	35.4%	25.9%	<0.001
Median CFS score (IQR)	4 (3 to 5)	5 (4 to 6)	<0.001
One-year mortality	20.8% (95% CI 16.2–25.0)	29% (95% CI 28.0–30.0)	0.002
Standardised mortality ratio (95% CI)	2.74 (2.10–3.40)	3.66 (3.6–3.8)	—

ASA, American Society of Anesthesiologists; CFS, Clinical Frailty Scale; NHF, native hip fracture; PFF, periprosthetic femur fracture; SHFA, Scottish Hip Fracture Audit. CFS comparison uses 2023 SHFA data (first full year of CFS collection).

Clinical Significance

An increasing threat

The incidence of periprosthetic femur fracture is rising in relation to a sustained increase in arthroplasty volumes and the number of people who remain active into older age. Robust national-level data have remained scarce. SNAP Femur is the most comprehensive nationwide study of epidemiological and outcome data to date.

SNAP Femur revealed parallels between PFF and hip fracture: both affect older adults, both confer substantial morbidity and mortality, and both patient groups could benefit from evidence-based multidisciplinary care. Significant functional decline was observed post-PFF, reflected by a median CFS increase from 4 to 5 following injury.

"The additional mortality effects approached that of hip fracture; the one-year mortality rate was 20.8%, and standardised mortality ratio was 2.74 — compared to 29% and 3.66 for hip fracture."
Hall AJ — FFN Summary, May 2026

Read the Fragility Fracture Network summary fragilityfracturenetwork.org · Newsletter feature & infographic

Take-home Messages

PFFs are less common than native hip fractures and are commonly sustained by patients living in their own home and who are less frail when compared with native hip fracture patients.

PFFs are morbid injuries with a one-year mortality rate of 20.8% and SMR of 2.74. Male sex, increased frailty, older age, and interprosthetic (UCS Type D) fractures were independently associated with higher mortality risk.

While treatment varies by fracture type, surgical technique does not appear to impact mortality, highlighting the need for individualised, multidisciplinary care. Time to theatre was not independently associated with mortality.

Most PFFs are likely missed by standard arthroplasty registries due to coding limitations. Routine inclusion in national audits is essential to better guide care and policy. Integration into national hip fracture registries, following the lead of the NHFD, is recommended.