Femoral Stem Fracture in Hip Revision Arthroplasty: A Systematic Literature Review of the Real-World Evidence

Abstract

Background Total hip arthroplasty (THA) presents as an excellent treatment for the osteoarthritic hip, demonstrating good survival rates. However, aseptic loosening and infection are the main causes of operative revision. The methods used in revision surgery are non-modular or modular THA implants. In addition to the abovementioned revision reasons for THA, this treatment could be associated with the possibility of femoral stem fracture, especially in the modular system. The topic of material failure has been focused on in the public media. The question arises as to how such media reports correlate with the published literature. The observed mentioned number of cases concerning a femoral stem fracture vary between one single case and up to 18.5% within a clinical study, thus presenting an inhomogeneous data situation with a large span. The specific aim of this systematic review is to establish facts and clarify the number of unforeseen events of a femoral stem fracture based on peer review articles and registry data. This clarification is important to us, as these media reports have led to uncertainty among patients. Methods A systematic review was performed in accordance with the PRISMA statement. Peer review articles in English and German, presenting original articles, meta-analyses, or case reports, were searched from the turn of the millennium up to December 2019. Only articles that reported a femoral stem component fracture, with content of clinical data as well as register data, were included. Relevant papers published after the defined research time frame were taken into account within the discussion. Results In total, 218 fractures of a femoral stem (141 primary and 77 revision THA) component could be identified within the selected literature. Most cases of a femoral stem fracture occurred in the modular THA implants compared to the non-modular stems. Regarding revision THA, in summary, 77 implants, presenting 23 non-modular and 54 modular implants, failed by means of femoral stem fracture. A review of 11 National Joint Registries shows a revision rate between 0.04 and 0.05% in only 2 registers according to the specific subject of a femoral stem fracture. For the remaining 9 registers, however, detailed information is lacking and only nonspecific information such as a generic “implant failure” or “other reason” (which can cover a multitude of causes) is supplied. Conclusion A femoral stem fracture presents a devastating complication for the patient, the surgeon as well as for the manufacturer of the implant. Modular THA implants play an increasingly valuable role concerning restoration of individual anatomy in modern THA revision surgery, especially within complex cases. Regarding revision procedures, data suggests a lower risk of femoral stem fracture for modular implants compared to primary procedures, while the risk of fracture for non-modular implants seems to increase during revision. Ultimately, it cannot be proven whether this is actually applicable, since the absolute number of implanted prosthesis systems is not known. Various implant-, patient-, and surgeon-related factors may lead to these reported femoral stem fractures. However, this systematic review suggests that this is, in general, a rare complication.

Dual Modular Titanium Alloy Femoral Stem Failure Mechanisms and Suggested Clinical Approaches

“…Since dual modularity in primary THA shows a lack of clinical benefit over the monoblock counterparts and provides no functional advantage, surgeons should restrict usage to a minimum (e.g., in cases of dysplasia or other femoral deformities) [46,99,105,110]. To our knowledge, there have been two similar review studies published recently [32,111]. Lex et al pointed out that even studies that described medium-term revision rates of primary THAs with a Ti-Ti stem-neck junction as acceptable see them as a sensible therapeutic option only in patients with hip deformities not amenable to correction using standard monoblock stems [32]; however, although sometimes statistically presented as a rare complication, modular neck fracture presents a devastating complication for the patient, surgeon, and manufacturer of the implant [111].…”

“…Lex et al pointed out that even studies that described medium-term revision rates of primary THAs with a Ti-Ti stem-neck junction as acceptable see them as a sensible therapeutic option only in patients with hip deformities not amenable to correction using standard monoblock stems [32]; however, although sometimes statistically presented as a rare complication, modular neck fracture presents a devastating complication for the patient, surgeon, and manufacturer of the implant [111]. Uniform terminology or a standard classification proposal is mandatory to define the location/area as well as the reason for the implant fracture in a standardised manner, to create more transparency, and to ease the comparison of results from different studies and registers [111].…”

Mechanisms of Premature Fracture in Modular Neck Stems Made of CoCrMo/Ti6Al4V and Ti6Al4V/Ti6Al4V Alloy

“…The recent literature data on survivorship of the modular neck stem THA system confirm a lower yield than the similar mono-block stem THA system in a comparable clinical environment with long-term follow-up [28][29][30][31][32][33].…”

Broken prosthetic distal inter-locking modular femur stem: a case report of rare implant type failure

“…It is observed that most case reports utilize the on-site methods available and detailed retrieval method of a planned case of revision hip for failed stem is often not available. 12,13 The common factors observed for a failing femoral stem are excess neck offset, extralong head and both where applied. Other significant risk factors were male sex, high body mass index, low neck segments and straight component design.…”