A review of atypical subtrochanteric femoral fractures in Northern Ireland between 2010 and 2014

Prevalence of Monogenic Bone Disorders in a Dutch Cohort of Atypical Femur Fracture Patients

Atypical femur fractures (AFFs), considered rare associations of bisphosphonates, have also been reported in patients with monogenic bone disorders without bisphosphonate use. The exact association between AFFs and monogenic bone disorders remains unknown. Our aim was to determine the prevalence of monogenic bone disorders in a Dutch AFF cohort. AFF patients were recruited from two specialist bone centers in the Netherlands. Medical records of the AFF patients were reviewed for clinical features of monogenic bone disorders. Genetic variants identified by whole-exome sequencing in 37 candidate genes involved in monogenic bone disorders were classified based on the American College of Medical Genetics and Genomics (ACMG) classification guidelines. Copy number variations overlapping the candidate genes were also evaluated using DNA array genotyping data. The cohort comprises 60 AFF patients (including a pair of siblings), with 95% having received bisphosphonates. Fifteen AFF patients (25%) had clinical features of monogenic bone disorders. Eight of them (54%), including the pair of siblings, had a (likely) pathogenic variant in either PLS3, COL1A2, LRP5, or ALPL. One patient carried a likely pathogenic variant in TCIRG1 among patients not suspected of monogenic bone disorders (2%). In total, nine patients in this AFF cohort (15%) had a (likely) pathogenic variant. In one patient, we identified a 12.7 Mb deletion in chromosome 6, encompassing TENT5A. The findings indicate a strong relationship between AFFs and monogenic bone disorders, particularly osteogenesis imperfecta and hypophosphatasia, but mainly in individuals with symptoms of these disorders. The high yield of (likely) pathogenic variants in AFF patients with a clinical suspicion of these disorders stresses the importance of careful clinical evaluation of AFF patients. Although the relevance of bisphosphonate use in this relationship is currently unclear, clinicians should consider these findings in medical management of these patients. © 2023 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Mortality Risk Following Atypical Femoral Fracture: a Systematic Review and Meta-analysis

OBJECTIVE

To summarize all available data, using systematic review and meta-analysis, to estimate 1.) one-year mortality risk following AFF and 2.) risk ratio of mortality following AFF versus TFF.

METHODS

Potentially eligible studies were identified from Medline and EMBASE databases from inception to February 2022 using search strategy that comprised of terms for "Atypical Femoral Fracture" and "Mortality". Eligible study must consist of a cohort of patients with atypical femoral fracture. Then, the study must report one-year mortality rate following AFF or report effect estimates with 95% confidence intervals (95% CIs) comparing incident mortality between patients with AFF and TFF. Point estimates with standard errors were retrieved from each study and were combined using the generic inverse variance method.

RESULTS

A total of 8,967 articles were identified. After two rounds of independent review by three investigators, we identified seven studies reporting one-year mortality rate of AFF and three studies comparing mortality rate of AFF versus TFF. Pooled analysis revealed pooled one-year mortality rate following AFF of 0.10 (95% CI, 0.05 - 0.16, I² 93.3%). Two studies compared mortality risks of the AFF versus TFF and revealed conflicting results.

CONCLUSION

One-year mortality rate following AFF was approximately 10%. However, evidence is insufficient to conclude if there was difference in mortality risk between AFF and TFF.

The Genetics of Atypical Femur Fractures-a Systematic Review

PURPOSE OF REVIEW

Atypical femur fractures (AFFs) are rare subtrochanteric or diaphyseal fractures regarded as side effects of bisphosphonates (BPs), possibly with a genetic background. Here, we summarize the most recent knowledge about genetics of AFFs.

RECENT FINDINGS

AFF has been reported in 57 patients with seven different monogenic bone disorders including hypophosphatasia and osteogenesis imperfecta; 56.1% had never used BPs, while 17.5% were diagnosed with the disorder only after the AFF. Gene mutation finding in familial and sporadic cases identified possible AFF-related variants in the GGPS1 and ATRAID genes respectively. Functional follow-up studies of mutant proteins showed possible roles in AFF. A recent small genome-wide association study on 51 AFF cases did not identify significant hits associated with AFF. Recent findings have strengthened the hypothesis that AFFs have underlying genetic components but more studies are needed in AFF families and larger cohorts of sporadic cases to confirm previous results and/or find novel gene variants involved in the pathogenesis of AFFs.

Subtrochanteric femoral fracture with postoperative chronic osteomyelitis treated successfully by 1-stage operation: a case report

Chronic osteomyelitis is a chronic infectious disease of bone tissue, which can cause necrosis of bone and surrounding soft tissue, and is a common complication of open fracture, internal fixation, diabetic foot and blood-borne bone infection. Traumatic osteomyelitis is caused by bone tissue infection after open fracture surgery or open reduction of fracture or other bone and joint surgery. The lesion is near the fracture end. Intramedullary infection is the most serious infection in acute stage, with high fever, chills and other toxemia symptoms, similar to acute hematogenous osteomyelitis. The other is the skin and muscle necrosis infection near the fracture, which makes Fractures that lose blood supply are exposed to air and become dry and necrotic, and the course of disease turns to chronic, often accompanied by infectious nonunion or bone damage. The course of disease is prolonged and the treatment is difficult. Subtrochanteric femoral fracture with postoperative chronic osteomyelitis is a rare condition requiring complex treatment. In the present study, we report on a 49-year-old male patient who received open reduction with intramedullary nail fixation due to subtrochanteric femoral fracture, but later suffered postoperative infection and developed chronic osteomyelitis. On the basis of the complete removal of the osteomyelitis lesion, we performed a 1-stage operation where free vascularized fibula was used to repair the bone defect, followed by effective internal fixation. The patient was followed up for 24 months and finally recovered from chronic osteomyelitis, with good functional recovery of the hip joint and a Harris score of 85.

Current Understanding of Epidemiology, Pathophysiology, and Management of Atypical Femur Fractures

PURPOSE OF REVIEW

To summarize reports published since the 2013 American Society of Bone and Mineral Research Task Force Report on atypical femoral fractures (AFF).

RECENT FINDINGS

The absolute incidence of AFFs remains low. AFFs are primarily associated with prolonged bisphosphonate (BP) exposure, but have also been reported in unexposed patients and those receiving denosumab for osteoporosis and metastatic bone disease. Asians may be more susceptible to AFFs. Lateral femoral bowing and varus hip geometry, which increase loading forces on the lateral femoral cortex, may increase AFF risk. Altered bone material properties associated with BP therapy may predispose to AFFs by permitting initiation and increasing propagation of micro-cracks. Relevant genetic mutations have been reported in patients with AFFs. Single X-ray absorptiometry femur scans permit early detection of incomplete and/or asymptomatic AFFs. Orthopedists recommend intramedullary rods for complete AFFs and for incomplete, radiologically advanced AFFs associated with pain and/or marrow edema on MRI. Teriparatide may advance AFF healing but few data support its efficacy. Greater understanding of biological and genetic predisposition to AFF may allow characterization of individual risk prior to initiating osteoporosis therapy and help allay fear in those at low risk for this complication, which remains rare in comparison to the osteoporotic fractures prevented by antiresorptive therapy.