CORR Insights®: What Is the Cumulative Incidence of Femoral Stem Revision and Stem Complication in Cemented and Uncemented Hip Arthroplasty for Proximal Femoral Metastatic Bone Disease?

Where Are We Now?

There has been a clear trend toward increased use of cemented implants in displaced hip fractures to reduce the risk of periprosthetic fracture, as illustrated by both large, registry-based studies [3] and the American Academy of Orthopaedic Surgeons (AAOS) Clinical Practice Guidelines [2]. This would seem to readily translate into the management of metastatic hip disease without any further consideration. A pathologic hip fracture in abnormal bone would likely have a lower risk of iatrogenic fracture with cemented implants. Cement also has the potential benefit of interdigitation with the host bone and has less reliance on the biology of bone to osseointegrate in the setting of radiation and/or chemotherapy. However, metastatic disease is often identified prior to fracture, and pathologic fractures can occur in an otherwise normal femur. In the setting of improving cancer survival [5], it is likely that patients will continue living with their metastatic bone disease as part of the ebb and flow of a smoldering malignancy. As these patients progress through life with increasingly complex surgical and medical histories, they may arrive at a hip fracture carrying substantially more comorbidities than the average patient. The incidence of bone cement implant syndrome in cemented metastatic hip fractures has been reported to be as high as 75%; however, the overwhelming majority of these cases resolve without clinically significant complications, and perioperative mortality is exceptionally rare [4]. Conversely, a younger patient with a favorable estimated cancer survival may lead the surgeon to use an uncemented femoral stem with the intent of providing a longer lasting implant.

In this issue of Clinical Orthopaedics and Related Research®, Lawrenz et al. [1] present a rationale for how uncemented implants are not necessarily contraindicated in patients with metastatic hip disease, and they suggest that careful patient selection can lead to comparable outcomes. The authors acknowledge that this is not an endorsement of uncemented implants for all patients with metastatic disease, but rather a framework for how to consider these implants for uncommon situations—situations that, in patients with cancer, seem more often to be the case than not. I applaud the authors for not only demonstrating the feasibility of uncemented implants in one of the largest cohorts of these patients, but also for explaining clearly their indications for this approach: age < 65 years, radiographically normal bone in the remaining femur, and an estimation that the femoral neck cut would remove all pathologic bone without additional curettage on radiographs. These are intuitively sensible and can be replicated by any surgeon who treats hip fractures. The limitations of this study are addressed quite clearly by the authors, and for this specific, highly selected cohort of patients, an uncemented stem appears to be a reasonable choice in comparison with a cemented stem.

Where Do We Need To Go?

While the study by Lawrenz and colleagues [1] provides a rationale and evidence for uncemented implants, their study includes a highly selected cohort of patients treated by experienced surgeons; as such, the work would benefit from replication in a registry setting, which would provide a larger patient sample and generalizability in terms of including surgeons with diverse training and experience levels. I’m especially interested to see whether less-experienced surgeons indeed can perform press-fitting with similar success in patients with metastatic hip disease. Both registry data sources and prospective studies have shortcomings in our search for answers here; it’s hard or impossible to determine surgical indications in registry studies, and prospective studies would require that surgeons commit to performing a less familiar operation and to standardizing indications about which there is a great deal of controversy. The real question is whether we should be considering uncemented implants at all in this patient population.

How Do We Get There?

Surgical decision-making occurs in a team setting, as indicated by the jointly released Musculoskeletal Tumor Society, American Society for Radiation Oncology, and American Society for Clinical Oncology (MSTS/ASTRO/ASCO) Metastatic Carcinoma and Myeloma of the Femur clinical practice guideline [6]. This guideline is important in part because it involved consensus work that included surgeons (MSTS), radiation oncologists (ASTRO), and medical oncologists (ASCO). The goal of this collaboration was to maximize both quantity and quality of life in these patients, and the answer to the question of cemented versus uncemented femoral stems in metastatic hip disease will require a similar multidisciplinary approach to properly account for the decision of who gets what surgery in the setting of radiation and systemic cancer therapy.

The best we may hope for in the short term is a retrospective analysis of a large, prospective registry, such as the AAOS Musculoskeletal Tumor Registry, which includes data on patient-reported outcomes. If enough uncemented stems are used in the database, an analysis of a well-indicated uncemented cohort to a matched cohort of cemented implants could provide meaningful data on the complication profiles of each in a sort of head-to-head comparison. These results could be further utilized for a cost-analysis model that incorporates differences in iatrogenic fracture rates, total blood loss if revision is needed, and most importantly, recovery time (including the time to get to comfortable, full weightbearing). Debating an often dogmatic choice of cemented stem in metastatic disease is worthwhile, and future research will hopefully continue to refine the right indication for the right patient.

Read This Next

• Here is a summary of the AAOS clinical practice guideline on metastatic carcinoma and myeloma of the femur, as well as consensus statements on the treatment of pending and completed pathologic femur fractures [6].

• In this study, a total of 12,491 patients were treated with hemiarthroplasty in a single healthcare system; the rates of revision were higher for those who received uncemented hemiarthroplasty [3].

• Here you can find a summary of the AAOS clinical practice guideline on management of hip fractures in older adults [2].