Atypical femur fractures in patients receiving bisphosphonate therapy: etiology and management

A brief review and clinical evidences of teriparatide therapy for atypical femoral fractures associated with long-term bisphosphonate treatment

The risk of bisphosphonate (BP)-associated atypical femur fracture (AFF) has markedly increased over recent decades due to suppression of bone turnover, accumulation of structural micro-damage and reduction of bone remodeling consequent to long-term BP treatment. These medications further delay bone union and result in challenging clinical management. Teriparatide (TPTD), a synthetic human parathyroid hormone, exhibits unique anabolic effects and can increase bone remodeling and improve bone microarchitecture, further promoting fracture healing and reducing the rate of bone non-union. In this study, we briefly define AFF as well as the effects of BPs on AFFs, detailed the role of TPTD in AFF management and the latest clinical therapeutic findings. We have confirmed that TPTD positively promotes the healing of AFFs by reducing the time to bone union and likelihood of non-union. Thus, teriparatide therapy could be considered as an alternative treatment for AFFs, however, further research is required for the establishment of effective clinical guidelines of TPTD use in the management of AFF.

Does Teriparatide Improve Fracture Union?: A Systematic Review

We conducted an updated review of the evidence of teriparatide (TPTD) for fracture healing for the following questions. (1) Does it decrease fracture healing time?; (2) Can it be an alternative treatment for nonunion?; (3) Does it aid the union of atypical femoral fracture (AFF)? We searched PubMed, EMBASE, and Cochrane Library including “Fracture” AND “nonunion” AND “Teriparatide”. In total, 57 publications met our inclusion criteria were summarized. This systemic review of the available literature revealed that TPTD works positively with regard to enhancing fracture healing time and union of AFF. There are also many case studies on the use of TPTD could be a potential new safe treatment for nonunion with no side effects. However, level 1 studies on the evidence of TPTD are still lacking so far. Over the last decade, a growing body of evidence has accumulated suggesting that TPTD can be an adjunct to enhance fracture healing or a therapeutic option to treat nonunion, but greater evidences from large volume prospective trials are needed.

A NEWLY DESIGNED ASSEMBLY LOCKING COMPRESSION PLATE TO TREAT COMMINUTED FRACTURES OF THE FEMORAL SHAFT: A BIOMECHANICAL STUDY

The aim of this paper is to compare the biomechanical characteristics of a newly designed assembly locking compression plate (NALCP) and traditional locking compression plate (LCP) for internal fixation of femoral-shaft comminuted fractures. A femoral-shaft wedge fracture model (AO classification 32-C2.1) was created in six pairs of femoral specimens ([Formula: see text]) randomly divided into two equal groups. Biomechanical properties were tested with axial and torsional loading tests. The relative maximum displacement of fracture blocks and strain was recorded. A strain diagram was made; the fatigue test results of NALCP specimens under axial load were recorded. Under axial load, the relative maximum displacement of fracture blocks in the [Formula: see text], [Formula: see text], and [Formula: see text] axes was smaller in NALCP specimens than in LCP specimens ([Formula: see text] and 0.01, respectively). Under torsional load, the relative maximum displacement of fracture blocks in the [Formula: see text] and [Formula: see text] axes in NALCP specimens was less than that in LCP specimens ([Formula: see text]) but no statistically significant difference in the [Formula: see text] axes ([Formula: see text]) was found. In both cases, the main NALCP strain was higher than the LCP strain ([Formula: see text]) but no statistically significant difference in mean strain ([Formula: see text]) was found. Our NALCP provides strong mechanical stability for comminuted femoral fractures and can effectively avoid stress concentration, reduce stress shielding, and facilitate bone healing.

Biofunctionalized peptide nanofiber-based composite scaffolds for bone regeneration

Bone tissue had moderate self-healing capabilities, but biomaterial scaffolds were required for the repair of some defects such as large bone defects. Peptide nanofiber scaffolds demonstrated important potential in regenerative medicine. Functional modification and controlled release of signal molecules were two significant approaches to increase the bioactivity of biofunctionalized peptide nanofiber scaffolds, but peptide scaffolds were limited by insufficient mechanical strength. Thus, it was necessary to combine peptide scaffolds with other materials including polymers, hydroxyapatite, demineralized bone matrix (DBM) and metal materials based on the requirement of different bone defects. As the development of peptide-based composite scaffolds continued to evolve, ultimate translation to the clinical environment may allow for improved therapeutic outcomes for bone repair.

Atypical femur fractures: a distinctive tract of adult hypophosphatasia

Hypophosphatasia (HPP) is a congenital, rare and heterogeneous bone disorder, characterized by a deficit of calcified tissue mineralization, leading to skeletal deformities and osteomalacia in adults, rickets in infants and children, and fragility fractures and premature loss of dentition in children and adults. The disease is caused by a reduced or absent expression and activity of the tissue non-specific alkaline phosphatase (TNSALP) enzyme, derived from inactivating mutations of the alkaline phosphatase (ALPL) gene. Six different clinical variants have been reported, defined by the onset age and characterized by different degrees of severity. The adult form of HPP presents a wide range of clinical manifestations, many of which are non-specific, mild, and often overlapping with other metabolic bone diseases. Consequently, many cases of adult HPP are, commonly, undiagnosed or misdiagnosed, and, subsequently, wrongly or non-treated with severe consequences for patients and a very negative impact on their quality of life and life expectancy, as well as with costs due to the administration of wrong therapies and treatments of their side effects. The occurrence of a fragility atypical femur fracture in the adulthood can be suspected as a clinical indication of an undiagnosed adult mild form of HPP; and the presence of at least one of this kind of fracture can help in the diagnosis of adult HPP, together with conventional HPP biochemical signs.

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

The term atypical femoral fractures most commonly occur in the subtrochanteric area. Concerns exist regarding the role of bisphosphonate treatment in their aetiology. Which surgical intervention provides the best outcome remains contentious. We reviewed all atypical subtrochanteric femoral fractures treated in Northern Ireland over 5 years, specifically investigating incidence, prodromal symptoms, association with bisphosphonates and optimal fixation methods. All subtrochanteric fractures treated in the region were identified and reviewed for atypical features. Case notes and imaging were then reviewed for each patient. A total of 364 subtrochanteric femoral fractures were identified during the 5-year study period. Twenty-six of these met the criteria for an atypical fracture (7%). Thirteen patients (50%) had presented with prodromal symptoms prior to complete fracture, six of which had radiological evidence of an incomplete fracture of the lateral cortex. Thirteen patients had a history of bisphosphonate treatment. All were treated operatively, with twenty-five cephalomedullary nails and one dynamic hip screw. Twenty-one patients had follow-up for greater than 2 months, nine of which (42.9%) achieved radiological union with a mean time to union of 297 days. Dynamically locked nails had a higher union rate than statically locked (80% versus 33.3%). Four patients required major revision surgery (15.4%). The quality of reduction was statistically significant in predicting need for revision. Atypical fractures often present with prodromal symptoms. Complete fractures are difficult to successfully manage with longer than expected times to union. Treatment with a dynamically locked, cephalomedullary with a good reduction provided the best results.

Efficacy of teriparatide in the treatment of nontraumatic osteonecrosis of the femoral head: a retrospective comparative study with alendronate

Background

Collapse of the femoral head associated with nontraumatic osteonecrosis (NOFH) is one of the most common causes of disability in young adult patients. Excessive bone resorption by osteoclast coincident with the suppression of osteogenesis are believed to be responsible for collapse progression. Alendronate that inhibits bone resorption by inducing osteoclast apoptosis has been traditionally used for treating NOFH; however, several reports documented serious complications by the use of this drug. On the other hand, teriparatide activates osteoblasts leading to an overall increase in bone volume, and is expected to reduce the progression of femoral head collapse in NOFH. Therefore, the present study was undertaken to examine pharmacological effects of teriparatide on collapse progression of NOFH and to compare these effects with alendronate.

Methods

We conducted a retrospective study in our facility for comparing the pharmacological effects of teriparatide and alendronate on 32 NOFH patients diagnosed with osteoporosis. Between 2007 and 2013, patients were treated with daily administration of 20 μg teriparatide (15 patients: 18 hips), or with 35 mg of alendronate once a week (17 patients: 22 hips). The mean period of follow-up was 18.7 months. The progression of collapse was evaluated prior to the administration and later every three months by anteroposterior radiographs. Collapse progression with > 1 mm was defined as advanced collapse, while with < 1 mm was defined as stable radiologic disease. Student’s t-test and the chi-square test was used to do compare the pharmacological effects of the two groups.

Results

Treatment with terparatide had a tendency to reduce the rate of advanced collapse as compared to that with alendronate (p = 0.105). Kaplan-Meier curves related to stable radiologic disease showed that teriparatide-treated patients had better stable states than these treated with alendronate (p = 0.08, log-rank test). Moreover, treatment with teriparatide resulted in a significant reduction in collapse progression as compared to that with alendronate, noted at the end of follow-up period (p = 0.049).

Conclusion

The present study suggests that teriparatide has greater pharmacological effects than alendronate for treating NOFH and preventing the collapse of femoral head.

Trial registration

The registration number in UMIN Clinical Trial Registry is UMIN000017582. The date of registration is May 5, 2015.

Unmet needs and current and future approaches for osteoporotic patients at high risk of hip fracture

This review provides a critical analysis of currently available approaches to increase bone mass, structure and strength through drug therapy and of possible direct intra-osseous interventions for the management of patients at imminent risk of hip fracture.

PURPOSE

Osteoporotic hip fractures represent a particularly high burden in morbidity-, mortality- and health care-related costs. There are challenges and unmet needs in the early prevention of hip fractures, opening the perspective of new developments for the management of osteoporotic patients at imminent and/or at very high risk of hip fracture. Amongst them, preventive surgical intervention needs to be considered.

METHODS

A European Society for Clinical and Economic Aspects of Osteoporosis, Osteoarthritis and Musculoskeletal Diseases (ESCEO)/International Osteoporosis Foundation (IOF) working group reviewed the presently available intervention modalities including preventive surgical options for hip fragility. This paper represents a summary of the discussions.

RESULTS

Prevention of hip fracture is currently based on regular physical activity; prevention of falls; correction of nutritional deficiencies, including vitamin D repletion; and pharmacological intervention. However, efficacy of these various measures to reduce hip fractures is at most 50% and may need months or years before becoming effective. To face the challenges of early prevention of hip fractures for osteoporotic patients at imminent and/or at very high risk of hip fracture, preventive surgical intervention needs further investigation.

CONCLUSION

Preventive surgical intervention needs to be appraised for osteoporotic patients at imminent and/or at very high risk of hip fracture.