Prophylactic augmentation of the osteoporotic proximal femur—mission impossible?

Abstract

The high incidence of secondary hip fractures and the associated markedly increased mortality call for preventive actions that could help to avoid these injuries. By providing immediate strengthening and not relying on patient compliance, internal prophylactic augmentation of the osteoporotic proximal femur may overcome the main limitations of systemic bone drugs and wearable protective pads. However, such a method would have to provide sufficient and reliable strengthening effect with minimal risks and side effects to justify the need of an invasive treatment. The requirements for an internal reinforcement approach are thus strict and include mechanical, biological, clinical, ethical and financial criteria. Here we first attempt to describe the properties of an ideal augmentation method. Previously published methodologies and techniques developed at our research institute, including approaches using cements, metals, other materials or combined approaches, are then reviewed and evaluated according to these aspects. We conclude that none of the discussed methodologies appears to be able to deliver a sufficiently high gain-versus-risk ratio that could justify the clinical application and thus augmentation of the osteoporotic proximal femur remains a challenge. Finally, we provide suggestions for the development and evaluation of future strategies.

In vitro injection of osteoporotic cadaveric femurs with a triphasic calcium‐based implant confers immediate biomechanical integrity

“…Previous efforts to prevent hip fractures using mechanical methods, reviewed in Varga et al, included prophylactic pinning with metal implants or a PEEK rod system, and injecting silicone rubber or PMMA . The metal systems in general failed to improve biomechanical properties and introduced concerns about stress risers . Using silicone rubber to fill the proximal femur failed to improve biomechanics .…”

“…In the osteoporotic femurs in this study, only 28% (7/25) of control femurs had a failure load greater than 2,900 N whereas 72% (18 of 25) of treated femurs exceeded the "fragile bone strength" threshold of 2,900 N. These data infer that the positive strength increment observed immediately after implant injection is likely to be clinically important and has the potential to reduce fracture risk. Previous efforts to prevent hip fractures using mechanical methods, reviewed in Varga et al, 38 included prophylactic pinning with metal implants 27,39 or a PEEK rod system, 20,26 and injecting silicone rubber 24,25 or PMMA. 19,[21][22][23]40 The metal systems in general failed to improve biomechanical properties and introduced concerns about stress risers.…”

“…19,[21][22][23]40 The metal systems in general failed to improve biomechanical properties and introduced concerns about stress risers. 38 Using silicone rubber to fill the proximal femur failed to improve biomechanics. 24,25 Femoral augmentation studies using large volumes of PMMA (30-40 cc) injected into the proximal femur reported up to an 80% increase in femoral failure load and up to a 188% increase in energy absorption.…”

Treatment of bone loss in proximal femurs of postmenopausal osteoporotic women with AGN1 local osteo-enhancement procedure (LOEP) increases hip bone mineral density and hip strength: a long-term prospective cohort study

“…In patients with a recent hip fracture, the risk of a second contralateral hip fracture is significantly elevated in the months after the first fracture, and remains elevated for years [13]. There is a growing global consensus among leading clinicians that minimally-invasive surgical approaches intended to complement current therapies warrant consideration to further reduce risk of fragility fracture in patients at elevated risk [11,14]. The recently published guidance on diagnosis and management of postmenopausal osteoporosis in women by the International Osteoporosis Foundation (IOF) and European Society of Clinical and Economic Aspects of Osteoporosis (ESCEO) included a local osteo-enhancement procedure (LOEP) as a treatment option [15].…”

Contralateral Prophylactic Reinforcement in Case of First Low-Energy Hip Fracture: First-in-Man Clinical Data of a New Percutaneous Internal Fixation Device

“…only 31% of included patients returned to their pre-injury walking ability. To address the issue of hip fragility fracture prevention, a new medical device, Y-STRUT ® (Hyprevention, France), was developed to be implemented in the proximal femur by minimally invasive surgery [22,23]. Biomechanical tests on human osteoporotic femurs showed that the implantable medical device, placed in the proximal femur, increases the bone fracture load and energy to fracture in case of fall without modifying or worsening the nature of the fracture [24].…”