PPF is a serious complication of THA, with an incidence on the rise [2, 10]. Previous studies have suggested that PPF could be of osteoporotic origin, as osteoporosis-related factors (age, female sex) were frequently observed in affected patients [7, 8]. However, while osteoporosis is typically considered as a contributing cause [14], no cross-sectional study has systematically investigated the frequency of osteoporosis in affected patients and compared DXA parameters with adequately matched control groups. Therefore, in this study, DXA outcomes of patients suffering from PPF were compared with those of controls, undergoing aseptic revision for other causes and primary THA for OA.

We demonstrated that 45% of the patients with PPF fulfilled the criteria of osteoporosis according to DXA measurements. Consistently, the mean BMD T-score was significantly lower than in both control groups consisting of patients undergoing aseptic revision or primary THA. With around 75% of cases being low-trauma fractures [2], PPF have a high rate of treatment-failure and mortality [15]. Demographic data suggest that most of these fractures may be related to osteoporosis. A recent study has shown that osteoporosis was present in 67 to 78% of patients with periprosthetic fractures, including but not limited to periprosthetic femoral hip fractures. The prevalence of osteoporosis varied depending on the diagnostic criteria used, including whether the diagnosis was made through clinical assessment and medical history or by using DXA or computed tomography data of the lumbar spine [16]. In another previous study, low BMD, defined as T-score ≤ − 1.0, was associated with a higher rate of intraoperative PPF compared to patients with normal BMD [17]. However, only twelve fractures were observed in total in this previous study, thus limiting the impact and generalizability of this finding. Indirect evidence supporting the potential osteoporosis-related nature of PPF was demonstrated by the fact that prior fragility fractures were shown to be a significant risk factor for PPF [18]. While other secondary causes may also cause PPF, for instance, aseptic or septic loosening with periprosthetic osteolysis (as defined per our exclusion criteria), osteoporosis has previously also been found to lead to a significantly higher number of medical, surgical, and overall complications in patients with PPF [19]. The collective evidence suggests that poor bone quality plays a major role with respect to the occurrence of PPF, but also in relation to poor outcomes and complications, which underlines the clinical importance of bone health assessment in hip arthroplasty.

High-risk patients should receive DXA prior to primary THA to allow appropriate treatment initiation [20]. In addition, repeated BMD assessments are also crucial as PPF can virtually occur at any time, with peaks in occurrence intraoperatively and early postoperatively [7, 8], but eventually also increasing over time [21, 22]. The guidelines of the National Osteoporosis Foundation recommend the fracture risk assessment tool (FRAX) for preoperative screening [23]. Studies investigating the effectiveness of this tool suggest that it has the potential to assess PPF risk and should ideally be calculated before and after THA [24]. However, there is a lack of implementation in everyday clinical practice. This is underlined by prior research, indicating that 75–80% of patients did not receive preoperative screening [10, 14], and of those at high risk of osteoporosis, around 10% received a DXA scan [5, 25]. Notably, there are currently no standardized definitions for identifying patients at high risk of osteoporosis in the context of arthroplasty. Therefore, clinicians typically rely on national guidelines and recommendations to define high-risk patients in general. In Germany, the national guideline defines a number of risk constellations in which screening for osteoporosis (primarily using DXA) should be initiated [12]. These include certain risk constellations in women aged 50 and over and in men aged 60 and over, including previous fragility fractures, rheumatoid arthritis, diabetes mellitus, neurological diseases, a history of proximal femur fracture in either parent, depression, heart failure, use of glucocorticoids > 2.5 mg, opioids, and many more. Furthermore, osteoporosis screening is recommended for women aged 70 and over and men aged 80 and over, regardless of any additional risk factors. However, as PPF may differ in their development from typical fragility fractures, one aim of future research is to determine individual risk constellations to identify high-risk patients who would benefit from DXA measurement prior to arthroplasty.

In addition to an adequate determination of BMD as a prerequisite for further preventive measures, the consequence of low BMD with regard to the surgical procedure, especially stem fixation, is a matter of ongoing debate. According to a previously conducted survey, over 60% of orthopedic surgeons reported that they would reconsider THA in cases of low BMD or would at least adapt the type of prosthesis fixation [26]. Furthermore, it is important to note that patients undergoing THA with uncemented stem fixation have a 14-and 10-times higher risk of intra- and postoperative PPF, respectively [21]. Based on these previous results, we hypothesized that patients with cemented stems would on average have to exhibit lower BMD values (i.e., more severe osteoporosis) to sustain a fracture. Indeed, when comparing DXA outcomes within our PPF cohort, we observed that patients with fractures around cemented stems showed a trend toward lower T-scores compared to uncemented stems, although this difference marginally failed to reach the statistical level of significance (p = 0.07). Additional age adjustment did not result in any significant differences in the corresponding Z-scores. Importantly, based on the aforementioned previous study [21] and further reinforced by our case study, cemented stem fixation should be considered for elderly patients and also in those with osteoporosis to minimize the risk of PPF.

Pharmacological treatment is the method of choice for improving BMD. More specifically, several studies have shown that periprosthetic BMD is improved by anti-resorptive drugs such as bisphosphonates or denosumab [27, 28], suggesting a reduction in PPF risk. Nevertheless, PPF risk reduction by bone-specific drugs has not yet been sufficiently investigated. Notably, the use of bisphosphonates, a first-line treatment for osteoporosis, before revision surgery was associated with an almost two-fold increase in implant survival time [29]. However, there are also contrasting observations that bisphosphonates may even increase the risk of intra- and postoperative PPF [30]. Nonetheless, the mentioned study did not account for osteoporosis severity as a confounding factor, which is why the diagnosis of osteoporosis rather than bisphosphonate treatment was most likely decisive for the increased rate of PPF [31].

A limitation of our study is that the number of included patients was rather small, which results in small sample sizes, especially for subgroup analyses within the PPF cohort. Additionally, the application of certain exclusion criteria may have impacted our ability to accurately determine the true prevalence of osteoporosis, potentially resulting in differences from what we have demonstrated. Nevertheless, this is the first study to compare gold standard-derived assessments of BMD using DXA measurements with adequately matched control groups in a cross-sectional study design. Other studies investigating the role of BMD on the occurrence of, for example, intraoperative PPF within a larger cohort of patients undergoing THA were ultimately limited by the occurrence of very few fractures [17]. A further limitation of our study is the inability of our study design to make predictive statements about DXA measurements in relation to fractures. However, it is noteworthy that our study is the first to adequately address and quantify the prevalence of osteoporosis within a PPF cohort. Therefore, there is a clear need for prospective studies to investigate the value of BMD measurements in the development of PPF. Finally, another limitation of our study is the absence of data on peripheral BMD, e.g., using forearm DXA or high-resolution peripheral quantitative computed tomography measurements. Further studies investigating the BMD at these sites and their predictive value on PPF should be conducted in the future.

In conclusion, patients who underwent revision surgery for PPF were significantly more likely to have osteoporosis compared to patients who underwent aseptic revision or primary THA. Consequently, it is likely that osteoporosis is a relevant risk factor for PPF that should be evaluated and treated to prevent and reduce the occurrence of this serious complication.