Atypical periprosthetic femoral fractures after arthroplasty for fracture are at high risk of complications

The definition of atypical femoral fractures should include periprosthetic femoral fractures (PAFFs)

Periprosthetic hip fractures may have features of atypical femoral fractures.

PURPOSE

Atypical femoral fracture (AFF) is a rare complication of treatment with bisphosphonates (BPs) or denosumab. The American Society for Bone and Mineral Research (ASBMR) Task Force definition for AFFs excludes periprosthetic fractures. The purpose of this study was to determine prodromal symptoms, frequency, treatment, and outcomes of periprosthetic AFFs (PAFFs) in persons prescribed a BP or denosumab for osteoporosis and later diagnosed with a periprosthetic hip fracture.

METHODS

Participants were all veterans (age ≥ 50) from the VA Corporate Data Warehouse with at least one filled prescription for an oral or intravenous BP or denosumab from October 1999 through December 2022, prior to an ICD code for a periprosthetic fracture around a hip joint. Radiographs were reviewed for features of AFF. In those with a PAFF, the presence of a contralateral AFF was sought. Medical records of those with a PAFF were reviewed to identify prodromal symptoms, treatments, and outcomes.

RESULTS

Among approximately 400,000 veterans who received a BP or denosumab, there were 76 ICD-coded periprosthetic hip fractures, including one AFF. This fracture met all five ASMBR-defined AFF criteria. The PAFF, a Vancouver C cemented periprosthetic femur fracture, occurred in a man with > 7 years of BP therapy. There was no contralateral AFF. The BP was discontinued and the fracture was treated with an interlocking plate with cerclage wires. In the 12 months following PAFF, there were no infectious complications, but the fracture had a chronic nonunion.

CONCLUSION

Periprosthetic hip fractures may rarely have features of AFFs. Fracture nonunion may complicate PAFFs.

Update on Atypical Femoral Fractures

➤ Atypical femoral fractures (AFFs) are stress fractures between the lesser trochanter and the metaphyseal flare that are most commonly related to prolonged (3 to 5 years) antiresorptive medication use.➤ An important finding is a visible transverse line in the lateral cortex, known as the "dreaded black line." Complete fractures are transverse and have minimal comminution.➤ Prodromal symptoms including hip, groin, thigh, and knee pain are present in more than one-half of cases and are usually misdiagnosed.➤ Nonoperative treatment for all patients with AFF includes withdrawal of bisphosphonates, assessment for secondary causes of osteoporosis, and optimization of vitamin D and calcium.➤ Incomplete fractures without a visible line can initially be treated nonoperatively with protected weight-bearing.➤ Intramedullary nailing is indicated for complete fractures and incomplete fractures with a visible fracture line. Delayed healing after fixation should be anticipated.➤ Treatment with parathyroid hormone (PTH) analogs (teriparatide and abaloparatide) after AFF prevents other fractures in high-risk patients, but the effect on healing of the fracture is unclear.

Atypical Periprosthetic Femoral Fracture Might be Considered a Distinct Subtype of Atypical Femoral Fracture: A Retrospective Study

OBJECTIVE

The exact relationship among atypical periprosthetic femoral fractures (APFFs), typical periprosthetic femoral fractures (PFFs), and atypical femur fractures (AFFs) remains unclear. This study aimed to investigate the prevalence of APFFs among PFFs and to identify the clinical characteristics, management, and prognosis that distinguish APFFs from typical PFFs and AFFs to further determine the relationship among these three fracture types.

METHODS

In this retrospective study, we reviewed the clinical data of 117 consecutive patients who had PFFs after hip arthroplasty between January 2012 and December 2022 and further classified them into an APFF group and a typical PFF group according to the revised ASBMR diagnostic criteria for AFF. Moreover, patients who had subtrochanteric or femoral shaft fractures in the same period and met the diagnostic criteria for AFF were recruited and classified into the AFF group. Demographic information, minor features of AFF, comorbidities, history of medication usage, management, and complications were collected and compared among patients with typical PFFs, APFFs, and AFFs.

RESULTS

Eleven PFFs were identified as APFFs, and the prevalence of APFFs among PFFs was 9.4%. Significant differences were found in generalized increase in cortical thickness (p = 0.019), prodromal symptoms (p < 0.001), and the incidence of bilateral fractures (p = 0.010) among the groups, where the incidences of these minor features in the APFF group and the AFF group were higher than those in the typical PFF group. Of note, the duration of fracture healing of APFFs was significantly longer than that of typical PFFs and AFFs (p < 0.001 and p = 0.004, respectively). In addition, the APFF group and the AFF group had higher proportions of patients with rheumatoid arthritis (p = 0.004 and p = 0.027, respectively), bisphosphonate (BP) usage (p = 0.026 and p < 0.001, respectively), and longer duration of BP usage (p = 0.003 and p = 0.007, respectively) than the typical PFF group. Furthermore, significant differences were found in management (p < 0.001) and complication rate (p = 0.020) among the groups, and the rate of complications in the APFF group and the AFF group was higher than that in the typical PFF group.

CONCLUSIONS

APFFs not only fulfilled the mandatory and major diagnostic criteria for AFF but also had many clinical characteristics, management and prognosis distinguishing them from typical PFFs but resembling AFFs; hence, the diagnostic criteria for AFF might be revised to incorporate APFF as a distinct subtype of the condition.

The Association of Postoperative Osteoporosis Therapy With Periprosthetic Fracture Risk in Patients Undergoing Arthroplasty for Femoral Neck Fractures

BACKGROUND

Displaced femoral neck fractures in older adults are generally treated with hip arthroplasty. One concern following hip arthroplasty is the risk for periprosthetic fractures (PPFs). Most patients who have hip fractures are candidates for antiosteoporotic therapy, but the impact of this treatment on PPFs is unknown. Therefore, the primary objective of this study was to evaluate whether patients treated with antiosteoporotic medical therapy had lower odds of PPFs following arthroplasty for hip fracture.

METHODS

Patients at least 65 years old who underwent hip arthroplasty for femoral neck fractures from 2010 to 2020 were identified in a national database. Patients were stratified based on whether they initiated antiosteoporotic therapy within 1 year of hip arthroplasty. Minimum follow-up was 1 year, and maximum follow-up was 10.6 years. The primary endpoint was cumulative incidence of PPF as determined using Kaplan-Meier and Cox proportional hazards regression analyses. Overall, 2,026 patients who underwent arthroplasty for femoral neck fracture received antiosteoporotic medications within 1 year following surgery (mean follow up 4.8 years; range 1.0 to 10.6 years) and 33,639 patients did not (mean follow up 4.1 years; range 1.1 to 10.3 years).

RESULTS

The 10-year cumulative incidence of PPF for patients treated for osteoporosis was 3.88% compared to 5.92% for those who were untreated (P < .001). Adjusting for covariates, patients who received osteoporosis treatment had a significantly lower risk for PPF than those who were untreated (hazard ratio (HR): 0.663; 95% confidence interval (CI): 0.465-0.861; P = .038).

CONCLUSION

The present study suggests that osteoporosis treatment is associated with lower incidence of PPF following hip arthroplasty for femoral neck fractures. Treatment of osteoporosis should be initiated in eligible patients who sustain a femoral neck fracture, especially those who undergo hip arthroplasty.

Atypical Periprosthetic Femoral Fracture Associated With Prolonged Bisphosphonate Therapy: A Two-Centered Retrospective Case Series and Literature Review

To date, atypical periprosthetic femoral fractures (APFFs) are not well-understood due to a relatively small number of studies on the topic. Moreover, there is a paucity of guidance regarding the appropriate treatment strategy. We would therefore like to present and analyze a series of five APFF cases (one incomplete APFF and four complete APFFs) that were treated in two university hospitals; a review of the literature is also provided. The results provide additional and useful information regarding the treatment strategy for APFFs.