Periprosthetic femoral fracture type and location are influenced by the presence of an ipsilateral knee arthroplasty implant: A case-control study of 84 interprosthetic femoral fractures

Risk of peri‑implant femoral fracture after cephalomedullary nailing in older patients with trochanteric fractures

INTRODUCTION

Despite the recent increase in the use of cephalomedullary nails for trochanteric hip fractures, factors that may be associated with peri‑implant femoral fracture (PIFF) after cephalomedullary nailing for trochanteric fractures remain unknown. We investigated the factors associated with PIFF after cephalomedullary nailing of trochanteric hip fractures in older patients.

METHODS

A nested case-control study was conducted using a database of patients aged ≥65 years who underwent surgery with cephalomedullary nails for trochanteric fractures caused by low-energy trauma during 2005-2021. The cases were defined as patients who developed PIFF after surgery, while controls were patients who did not develop PIFF and who were followed up for ≥3 years after surgery. Four controls were randomly matched to each case for sex and age. First, potential factors associated with PIFF were compared between cases and controls. Second, multivariable conditional logistic regression analysis was employed to assess factors possibly associated with PIFF, controlling for potential confounding factors.

RESULTS

Of 1531 patients who underwent surgery with cephalomedullary nails because of trochanteric fractures, we assessed 34 cases and 136 controls (N = 170; mean age 85.7 ± 7 years; and females, 94 %). PIFF was significantly associated with patients having undergone total knee arthroplasty (adjusted odds ratios [95 % confidence intervals], 4.41 [1.16-16.8]) and those with AO/OTA classification 31A3 fracture (A3 fracture) (2.3 [1.12-4.76]), after adjusting for potential confounding factors.

CONCLUSIONS

Our results showed that PIFF was more likely to develop among older patients with a clinical history of total knee arthroplasty and A3 fracture. These findings suggest that such patients may require careful follow-up with rigorous assessments after cephalomedullary nailing for trochanteric fractures.

Incidences and Outcomes of Operatively Treated Interprosthetic Femoral Fractures Compared to Vancouver Type C and Rorabeck Type II Fractures

BACKGROUND

This case-control study evaluated the incidences and outcomes of interprosthetic femoral fracture (IPFF) (Group I) and performed comparisons with Vancouver type C (Group II) and Rorabeck type II (Group III) periprosthetic femoral fractures (PPFF) occurring at similar anatomic sites.

METHODS

A retrospective analysis was performed for all patients who had a previously implanted total hip arthroplasty (THA) and total knee arthroplasty (TKA), who lived in the hospital district and had undergone surgery due to PPFF. A total of 153 PPFFs [Group I (n = 31), Group II (n = 21), and Group III (n = 108)] were included. The annual incidences of PPFFs were summarized per 100,000 individuals. The risks of complications, reoperations, and mortalities were evaluated for all groups.

RESULTS

The mean population-based annual incidence was 0.9 per 100,000 person years for Group I, 0.7 per 100,000 person years for Group II, and 3.1 per 100,000 person years for Group III. A total of 25 of 153 (16%) major complications were found and 23 of 153 (13%) cases resulted in a revision surgery. The cumulative incidence of death in Group I was 50.4% at 10 years, in Group II it was 63.8% at 10 years, and in Group III it was 74.9% at 10 years.

CONCLUSION

The annual incidence of the IPFF almost doubled while the incidence of Vancouver type C stayed stable and Rorabeck type II incidence increased 5-fold. Most of the major complications occurred in IPFF group, while Rorabeck type II patients had the worst survival.

Surgical approaches to periprosthetic femoral fractures for plate fixation or revision arthroplasty

Periprosthetic femoral fractures are increasing in incidence, and typically occur in frail elderly patients. They are similar to pathological fractures in many ways. The aims of treatment are the same, including 'getting it right first time' with a single operation, which allows immediate unrestricted weightbearing, with a low risk of complications, and one that avoids the creation of stress risers locally that may predispose to further peri-implant fracture. The surgical approach to these fractures, the associated soft-tissue handling, and exposure of the fracture are key elements in minimizing the high rate of complications. This annotation describes the approaches to the femur that can be used to facilitate the surgical management of peri- and interprosthetic fractures of the femur at all levels using either modern methods of fixation or revision arthroplasty.

Which Unified Classification System type B periprosthetic fractures around cemented polished tapered stems should not be fixed?

The Unified Classification System (UCS), or Vancouver system, is a validated and widely used classification system to guide the management of periprosthetic femoral fractures. It suggests that well-fixed stems (type B1) can be treated with fixation but that loose stems (types B2 and B3) should be revised. Determining whether a stem is loose can be difficult and some authors have questioned how to apply this classification system to polished taper slip stems which are, by definition, loose within their cement mantle. Recent evidence has challenged the common perception that revision surgery is preferable to fixation surgery for UCS-B periprosthetic fractures around cemented polished taper slip stems. Indications for fixation include an anatomically reducible fracture and cement mantle, a well-fixed femoral bone-cement interface, and a well-functioning acetabular component. However, not all type B fractures can or should be managed with fixation due to the risk of early failure. This annotation details specific fracture patterns that should not be managed with fixation alone.

Risk of Interprosthetic Femur Fracture Is Associated with Implant Spacing-A Biomechanical Study

BACKGROUND

Ipsilateral revision surgeries of total hip or knee arthroplasties due to periprosthetic fractures or implant loosening are becoming more frequent in aging populations. Implants in revision arthroplasty usually require long anchoring stems. Depending on the residual distance between two adjacent knee and hip implants, we assume that the risk of interprosthetic fractures increases with a reduction in the interprosthetic distance. The aim of the current study was to investigate the maximum strain within the femoral shaft between two ipsilateral implants tips.

METHODS

A simplified physical model consisting of synthetic bone tubes and metallic implant cylinders was constructed and the surface strains were measured using digital image correlation. The strain distribution on the femoral shaft was analyzed in 3-point- and 4-point-bending scenarios. The physical model was transferred to a finite element model to parametrically investigate the effects of the interprosthetic distance and the cortical thickness on maximum strain. Strain patterns for all parametric combinations were compared to the reference strain pattern of the bone without implants.

RESULTS

The presence of an implant reduced principal strain values but resulted in distinct strain peaks at the locations of the implant tips. A reduced interprosthetic distance and thinner cortices resulted in strain peaks of up to 180% compared to the reference. At low cortical thicknesses, the strain peaks increased exponentially with a decrease in the interprosthetic distance. An increasing cortical thickness reduced the peak strains at the implant tips.

CONCLUSIONS

A minimum interprosthetic distance of 10 mm seems to be crucial to avoid the accumulation of strain peaks caused by ipsilateral implant tips. Interprosthetic fracture management is more important in patients with reduced bone quality.

Interprosthetic Femur Fractures: A Review Article

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The prevalence of interprosthetic femur fractures (IFFs) is rising with the aging population and increased prevalence of total joint arthroplasty.

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IFFs have high rates of complications and high associated morbidity and mortality.

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The main treatment methods available for IFFs include plate fixation, intramedullary nailing, combined plate fixation and intramedullary nailing, and revision arthroplasty including partial and total femur replacement.

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There have been several proposed classification systems and at least 1 proposed treatment algorithm for IFFs; however, there is no consensus.

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Whichever treatment option is chosen, goals of surgery should include preservation of blood supply, restoration of length, alignment, rotation, and sufficient stabilization to allow for early mobilization.