The primary aim of this study was to gain insight into the current usage of femoral megaprostheses in England, Wales, Northern Ireland and the Isle of Man, as recorded in the NJR. By conducting an analysis of centers currently contributing data to the NJR, we also hoped to further understand the extent to which low volume MPR practice is occurring.
Unsurprisingly, MPR use was generally highest in the revision arthroplasty categories, and in the hip revision group in particular. MPR use in the primary hip category was consistently higher than in the primary knee category throughout the study period, and, interestingly, also higher than in the revision knee category until 2017.
Excluding 2020 (when a presumed COVID-19-associated decline in megaprosthesis use was observed in all categories ), our data suggest that femoral megaprosthesis use, within the geographical region studied, increased between 2003–2019. Particularly, megaprosthesis use in the context of non-oncological indications rose, with trauma becoming the leading indication in both hip and knee revision categories. This finding is reflected elsewhere in the literature: currently existent center-level datasets now consist exclusively of patients undergoing femoral megaprosthesis procedures for non-oncological indications  and systematic reviews have also reported the outcomes of patients treated with MPR for non-oncological indications . Taken together, this clearly demonstrates that the use of femoral megaprostheses has become an accepted practice in certain non-oncological scenarios. Part of the explanation for their increasing use may be the growing range of options and availability of MPRs, training exposure over time, and the increasing burden of peri-prosthetic fracture management.
It should be noted that previous single-center case series of femoral MPR use for oncological indications demonstrate higher case numbers [8, 14, 15] than whole systematic reviews investigating non-oncological uses of femoral megaprostheses . This suggests that the most common indication for femoral megaprosthesis use remains malignancies. From the figures obtained by reviewing NJR data, the opposite conclusion would be drawn, highlighting the challenges faced with sporadic NJR submission.
When analyzing this dataset, the reliability of data submitted to the NJR must be considered. There are several reasons why the NJR data may not provide an accurate reflection of current trends in MPR practice. One is that surgeons may not input data for those cases likely to have a poor outcome (i.e. in cases of malignancy) due to concerns over the publication of outcomes. The likely presence of this scenario is supported by our review of published unit-level data, which suggests that several large tertiary referral centers are performing many more MPRs than recorded in the NJR. One example is a retrospective review of instability following megaprosthesis use for proximal femoral tumors comprising of 527 patients treated at a single institute . Considering this, we recognize that the true accuracy of the data and trends presented here are difficult to ascertain in the context of non-mandatory submission. Complicating MPR submission to the NJR further are several issues relating to how megaprosthetic procedures fit with the existing NJR data entry structure. For example, a total femoral replacement would require submission of both hip and knee forms, hemiarthroplasty articulations are not technically covered by the current system, and diaphyseal procedures have no mechanism for registration. These limitations can be addressed and overcome by the use of a megaprosthesis-specific data entry form.
Another important finding is the apparent large number of centers identified which have performed very low numbers of femoral MPRs. In all procedure categories, vast numbers of centers submitted just one case to the NJR, over the 17-year period. A similar finding was observed when this analysis was repeated for data from 2015–2020 only, an analysis we chose to perform to discard the NJR's early years when submission rates were lower than they are currently. These findings strongly suggest that current practice is at odds with the recommendations made as part of the Getting It Right First Time (GIRFT) review, which recommends that activities of high complexity should be concentrated in specialist units, within regional networks, to provide the best possible patient care [16, 17]. The volume of units that have submitted data in recent years suggest that further action is needed to ensure that GIRFT recommendations are met for megaprosthesis procedures. These findings are similar to those identified by the working group in revision knee surgery, when analyzing the provision of revision knee surgery in England, Wales, Northern Ireland and the Isle of Man , highlighting the fact that this is unlikely to be an isolated issue relating to MPR procedures. Non-specialist orthopedic services should seek to reduce the level of low volume practice highlighted in this study, and this may be achieved, in part, by the ongoing evolution of the regional networks and centralization of specialist care provision.
Although the true volume, indications and breadth of care provision for MPR work is difficult to ascertain from review of NJR data, findings identified within this study remain relevant to orthopedic practice and to help drive quality improvement. It is clear from the data presented that femoral MPRs were used for a wide variety of indications, beyond the oncological reconstructions for which they had been originally designed. The under-reporting highlighted in this study and the described reasons for this demonstrate the need for changes in the way that MPR procedures are entered into the registry to facilitate the monitoring of implants, meaningful research and the monitoring of specialist service provision. To facilitate this, a megaprosthesis-specific NJR data entry form has been developed for implementation into clinical practice.
Additionally, support is given for amendments to the processing of all procedures with malignancies as the given indication, so that these cases do not contribute to individual, unit or global outcomes. This amendment would provide surgeons with the confidence to accurately report all such procedures being performed, and in doing so create opportunities for meaningful research and improve the understanding of specialist care provision nationally.