Beware of bone pain with bisphosphonates

Bilateral Atypical Femoral Fractures after Bisphosphonate Treatment for Osteoporosis: A Literature Review

INTRODUCTION

This literature review aimed to investigate the incidence, anatomical concerns, etiology, symptoms, diagnostic tools, management, and prognosis of bisphosphonate (BP)-associated bilateral atypical femoral fractures (AFFs).

METHODS

The PubMed, Cochrane Library, Web of Sciences, and CINAHL databases were searched up to 20 March 2022. All cases of bilateral AFFs were included, excluding those without any bisphosphonate treatment information and those in which the femoral fracture did not precisely fit into the diagnostic criteria for AFF.

RESULTS

We identified 43 patients with bilateral AFFs associated with BP use and conducted a comprehensive analysis. Among 43 patients, 29 (67%) had prodromal symptoms. Regarding the simultaneity of fracture, 21 cases (49%) occurred simultaneously, and 22 cases (51%) occurred sequentially. Alendronate was the most commonly used BP treatment (59%). Regardless of the medication type, BP intake duration was more than 5 years in 77%. The initial diagnosis was performed using X-rays in all cases. A total of 53% of patients had complete fractures, and all patients underwent surgical treatment. Among the remaining patients with incomplete fractures, 18% and 29% received surgical and medical treatments, respectively. After BP discontinuation, teriparatide was most commonly used (63%).

CONCLUSIONS

The careful evaluation of relevant imaging findings in patients with thigh/groin pain allows the identification of early incomplete fractures and timely management. Since the rate of contralateral side fractures is also high, imaging studies should be performed on the asymptomatic contralateral side.

Bisphosphonate-based hydrogel mediates biomimetic negative feedback regulation of osteoclastic activity to promote bone regeneration

The intricate dynamic feedback mechanisms involved in bone homeostasis provide valuable inspiration for the design of smart biomaterial scaffolds to enhance in situ bone regeneration. In this work, we assembled a biomimetic hyaluronic acid nanocomposite hydrogel (HA-BP hydrogel) by coordination bonds with bisphosphonates (BPs), which are antiosteoclastic drugs. The HA-BP hydrogel exhibited expedited release of the loaded BP in response to an acidic environment. Our in vitro studies showed that the HA-BP hydrogel inhibits mature osteoclastic differentiation of macrophage-like RAW264.7 cells via the released BP. Furthermore, the HA-BP hydrogel can support the initial differentiation of primary macrophages to preosteoclasts, which are considered essential during bone regeneration, whereas further differentiation to mature osteoclasts is effectively inhibited by the HA-BP hydrogel via the released BP. The in vivo evaluation showed that the HA-BP hydrogel can enhance the in situ regeneration of bone. Our work demonstrates a promising strategy to design biomimetic biomaterial scaffolds capable of regulating bone homeostasis to promote bone regeneration.

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HA-BP hydrogel can mediate the expedited release of BP in response to the acidic microenvironment created by osteoclasts.

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HA-BP hydrogel supports preosteoclastic differentiation, but inhibits the further osteoclastic maturation.

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The implantation of HA-BP hydrogel in critical-sized bone defects significantly promotes in situ bone regeneration in vivo.

Tribological and Antibacterial Properties of Polyetheretherketone Composites with Black Phosphorus Nanosheets

Over the past few decades, polyetheretherketone (PEEK) artificial bone joint materials faced problems of poor wear resistance and easy infection, which are not suitable for the growing demand of bone joints. The tribological behavior and wear mechanism of polyetheretherketone (PEEK)/polytetrafluoroethylene (PTFE) with black phosphorus (BP) nanosheets have been investigated under dry sliding friction. Compared with pure PEEK, the COF of PEEK/10 wt% PTFE/0.5 wt% BP was reduced by about 73% (from 0.369 to 0.097) and the wear rate decreased by approximately 95% (from 1.0 × 10⁻⁴ mm³/(N m) to 5.1 × 10⁻⁶ mm³/(N m)) owing to the lubrication of the BP transfer film. Moreover, BP can endow the PEEK composites with excellent biological wettability and antibacterial properties. The antibacterial rate of PEEK/PTFE/BP was assessed to be over 99.9%, which might help to solve the problem of PEEK implant inflammation. After comprehensive evaluation in this research, 0.5 wt% BP nanosheet-filled PEEK/PTFE material displayed the optimum lubrication and antibacterial properties, and thus could be considered as a potential candidate for its application in biomedical materials.

Management Challenges in Atypical Femoral Fractures: A Case Report

A 78-year-old woman presented with an atypical femoral fracture of her right femur associated with a left thigh stress fracture following 9 years of bisphosphonate therapy. The fracture was managed with femoral nailing. However, she represented 3 years later with peri-prosthetic infection, worsening of the left-side stress fracture, and low bone turnover in a bone metabolic study, consistent with an ongoing bisphosphonate effect. This case highlights the increased rate of postoperative complications in atypical femoral fractures even years after surgery as well as the challenging management issues for contralateral fracture and the risk of missing bilateral fractures.