Does the lateral plate need to overlap the stem to mitigate stress concentration when treating Vancouver C periprosthetic supracondylar femur fracture?

Osteosíntesis en fracturas femorales periprotésicas de cadera Vancouver tipos B1 y C. Análisis multicéntrico

Introducción: Nuestro objetivo fue analizar los resultados del tratamiento con osteosíntesis en pacientes con fracturas Vancouver tipos B1 y C, evaluar las complicaciones, las reintervenciones y la tasa de mortalidad en este grupo. Materiales y Métodos: Estudio multicéntrico, retrospectivo. Se estableció una base de datos que incluía a 53 pacientes con fracturas periprotésicas de fémur Vancouver tipos B1 y C tratadas con osteosíntesis, desde 2008 hasta 2021, en dos centros hospitalarios de alta complejidad. Resultados: La fijación proximal más utilizada fue con tornillos bicorticales más lazadas de alambre. El tipo de fractura según la clasificación de Vancouver se correlacionó con un valor significativo en el uso de tornillos de compresión interfragmentaria (p 0,001), con un total de 13 pacientes (24,52%), 9 en fracturas Vancouver tipo C. El tiempo de consolidación promedio fue de 4 meses, con un puntaje promedio del Harris Hip Score de 68. Doce pacientes (22,64%) tuvieron complicaciones: retraso de la consolidación (7 casos; 13,2%), falla de la osteosíntesis con trazo de fractura a nivel distal del tallo (un caso; 1,88%), una nueva osteosíntesis por falla a nivel del material de osteosíntesis (un caso; 1,88%) y tres fallecieron (5,66%). Conclusiones: El manejo de las fracturas femorales periprotésicas es un tema complejo y desafiante. El tratamiento con osteosíntesis constituye un método exitoso que requiere de la aplicación de principios actuales de técnicas mínimamente invasivas que, junto con una fijación proximal estable, mejoran las posibilidades de éxito.

Peri-implant femoral fractures: Challenges, outcomes and proposal of a treatment algorithm

PURPOSE

Non-prosthetic peri-implant fractures are challenging injuries. Multiple factors must be carefully evaluated for an adequate therapeutic strategy, such as the state of bone healing, the type of implant, the time and performed personnel of previous surgery, and the stability of fixation. The aim of this study is to propose a rationale for the treatment.

METHODS

The peri-implant femoral fractures (PIFFs) system, a therapeutic algorithm was developed for the management of all patients presenting a subtype A PIFF, based on the type of the original implant (extra- vs. intra-medullary), implant length and fracture location. The adequacy and reliability of the proposed algorithm and the fracture healing process were assessed at the last clinical follow-up using the Parker mobility score and radiological assessment, respectively. In addition, all complications were noticed. Continuous variables were expressed as mean and standard deviations, or median and range according to their distribution. Categorical variables were expressed as frequency and percentages.

RESULTS

This is a retrospective case series of 33 PIFFs, and the mean post-operative Parker mobility score was (5.60 ± 2.54) points. Five patients (15.1%) achieved complete mobility without aids (9 points) and 1 (3.0%) patient was not able to walk. Two other patients (6.1%) were non-ambulatory prior to PPIF. The mean follow-up was (21.51 ± 9.12) months (range 6-48 months). There were 7 (21.2%) complications equally distributed between patients managed either with nailing or plating. There were no cases of nonunion or mechanical failure of the original implant.

CONCLUSION

The proposed treatment algorithm shows adequate, reliable and straightforward to assist the orthopaedic trauma surgeon on the difficult decision-making process regarding the management of PIFF occurring in previously healed fractures. In addition, it may become a useful tool to optimize the use of the classification, thus potentially improving the outcomes and minimizing complications.

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.

Computational analysis of the effects of interprosthetic distance on normal and reduced cortical thickness femur models

Distal femoral fractures associated with the femoral stem in a well-fixed hip arthroplasty pose a risk of an interprosthetic fracture, the treatment of which is known as difficult. To effectively prevent and treat IP fractures, biomechanical effects must be demonstrated. We defined eight variations of the interprosthetic distance ranging from 48 mm overlap to 128 mm gap. Femoral geometries with normal and reduced cortical thickness were modeled to evaluate the effects of cortical thickness. In addition to the intact model, a total of 16 finite element models were analyzed under physiological boundary conditions. Maximum and minimum principal strains on the lateral and medial cortex surfaces were always found to be greater in models with reduced cortical thickness than in normal femurs. The model with 48 mm overlapping interprosthetic distance produced the least peak strain and the model with 16 mm interprosthetic gap produced the greatest strain with both normal and reduced cortical thickness. The screw holes produced local strain concentrations and increased the peak strains on the cortex surfaces, especially close to the stem tip. Statistically, a significant correlation (R² = 0.9483) was found between strain shielding and interprosthetic distance. Axial stiffness, interfragmentary shear motion, and maximum von-Mises stress on the distal plate showed a high correlation with the interprosthetic distance. It was concluded that the overlapping structures are superior to other fixations we analyzed in that they offer better mechanical stability and eliminates the local strain concentrations.

The Treatment of Periprosthetic Distal Femoral Fractures After Total Knee Replacement: A Critical Analysis Review

Periprosthetic distal femoral fracture after total knee arthroplasty carries substantial morbidity and mortality regardless of fixation technique. Surgical treatment is favored in most patients compared with conservative therapy because of high rates of nonunion, malunion, and reoperation after casting or bracing. Internal fixation techniques including retrograde intramedullary nailing and locked plating are favored for surgical treatment in most fractures when bone stock in the distal fragment allows for appropriate fixation. In the setting of deficient distal femoral bone stock or femoral component loosening, revision arthroplasty with distal femoral replacement is the favored technique. Further studies with regard to the use of intramedullary nailing, locked plating, and distal femoral replacement are necessary to refine the indications for each technique and to define the use of combinations of these fixation techniques.

Osteoporotic distal femur fractures in the elderly: peculiarities and treatment strategies

Distal femur fractures account for 4-6% of osteoporosis related fractures of the femur in the elderly population. They represent a relevant cause of morbidity and mortality in the geriatric population with a reported 1-year mortality reaching 30%. Non-displaced fractures or even displaced fractures in patients with high operative risk can be treated conservatively. However, operative treatment is the most widely accepted management option for displaced fractures. The advantage resides in early mobilization and weight-bearing, reducing risks related with a prolonged immobilization when compared with conservative treatment. On the other hand, the intrinsic difficulty of fixing an osteoporotic bone is a major concern. The presence of osteosynthesis devices or prosthetic implants in the femur can make the surgical treatment more challenging, sometimes limiting therapeutic options. Aim of the present paper is to review the most recent literature about osteoporotic distal femur fractures in the elderly, including periprosthetic and other hardware related fractures, to highlight current evidence on management options and related results as a guide for the daily clinical practice.

Optimal plate fixation of distal femoral fractures in the presence of a well fixed cemented hip arthroplasty femoral stem

INTRODUCTION

The requirement for lateral plate fixation in the presence of a hip arthroplasty stem is increasing, yet the optimal plate construct necessary to reduce inter-prosthetic strain and prevent subsequent fractures is unknown. Therefore, the purpose of this study was to determine the optimal position of a lateral femoral plate in relation to a femoral stem.

METHODS

We used 4th Generation Composite Sawbones^®, a collarless polished cemented femoral stem and a broad Peri-loc™ plate with varying overlap of the stem. Each construct was subjected to torsion, axial compression and 3-point lateral bending, with the strain measured at the tip of the femoral stem and the force-to-failure recorded.

RESULTS

In all three loading directions a plate, which extended at least two shaft diameters proximal to the tip of the stem, experienced the lowest strain ( p < 0.001). Constructs with no overlap, and particularly those with a small gap between the tip of the stem and the proximal extent of the plate experienced the highest strain ( p < 0.001). This high strain resulted in lower forces required to cause fracture in the clinically significant scenarios of femoral torsion and lateral bending.

CONCLUSIONS

Optimal plate fixation is achieved by extending a lateral femoral plate at least two shaft diameters proximal to the tip of the stem and using a spread of proximal screws. Distal fixation increases the strain experienced at the tip of the stem and higher strains are noted the smaller the gap between the proximal extent of the femoral plate and the tip of stem.

Non-prosthetic peri-implant fractures: classification, management and outcomes

INTRODUCTION

Non-prosthetic peri-implant fractures (NPPIFs) are an under-reported entity. Management is challenging because of alterations in anatomy, the presence of orthopaedic implants and phenomena such as stress shielding, disuse osteopenia and fracture remodeling. The aims of this paper were to review patterns of injury, management and outcomes and to propose a classification system to aid further research.

MATERIALS AND METHODS

This study is a multi-centered retrospective case series. Patients were identified from the orthopaedic department trauma databases of public hospitals in Singapore and individual surgeon case series of members of the Singapore Orthopaedic Research Collaborative (SORCE) group.

RESULTS

We collected a series of 60 NPPIFs in 53 patients. 38 fractures involved the femur, 12 the radius/ulna, 5 humeri, 3 tibia/fibula and 1 clavicle. 39 patients had fractures around plates and screws, 12 around nails, and 3 around screws. Fractures were managed with a variety of surgical techniques. Six patients had surgical complications with refracture in four and non-union in two cases. Two patients had multiple refractures (total 12 additional fractures). All surgical complications required further surgery. Three patients had deep vein thrombosis and one patient died of post-operative pneumonia. Fractures were classified according to the initial implant (plate or nail), the position of the new fracture relative to the original implant (at the tip or distant) and the status of the original fracture (healed, not healed or failing). Surgical strategies for common subtypes were reviewed.

CONCLUSIONS

This study represents the largest series in the literature. NPPIFs are a challenging clinical problem with a high rate of post-operative complications. They are distinct from peri-prosthetic fractures and should be understood as a separate entity. We, therefore, propose a novel classification system. Further research is needed to determine the optimal treatment for the various subtypes.

LEVEL OF EVIDENCE

Therapeutic Level IV-case series.

Interprosthetic Fractures of the Femur

As the rate of hip and knee arthroplasty procedures increases, so will the rate of interprosthetic fractures. Several factors, including bone quality, bone quantity, and stability of the prosthetic components, play a role in determining the appropriate operative treatment. Patients with stable components should undergo reduction and internal fixation, while patients with loose components should undergo either revision arthroplasty, with or without additional fixation, or conversion to total femur replacement. Despite implant and technique advances, complications remain frequent. [Orthopedics. 2018; 41(1):e1-e7.].

Periprosthetic Femoral Fractures in the Emergency Department: What the Orthopedic Surgeon Wants to Know

Femoral fracture in the setting of a hip arthroplasty is an increasingly common complication encountered in the emergency department (ED). Diagnosis and management of periprosthetic fractures are complicated, and orthopedic surgeons rely on imaging findings to guide the appropriate management approach to the injury. Delay in identification and appropriate definitive management of periprosthetic fractures is associated with high morbidity and mortality. At present, the Vancouver classification system for periprosthetic hip fractures is the most common classification system used by orthopedic surgeons. It relies on three radiographic criteria-fracture location, prosthesis stability, and quality of the femoral bone stock-to characterize these fractures and to help guide management decisions. Familiarly with the Vancouver classification system allows radiologists to both recognize and communicate the most clinically relevant imaging findings to the treating orthopedic surgeon. This article reviews the imaging workup for hip pain in patients with a femoral prosthesis, risk factors for periprosthetic fracture, and the expected normal appearance of the most commonly encountered types of femoral prostheses. Fracture terminology and the Vancouver classification system are reviewed in a simplified algorithm with emphasis on the most common patterns of periprosthetic fractures, the radiologic determinants of prosthesis stability and bone quality, and the management implications of these imaging findings. Finally, multiple instructive clinical cases are used to demonstrate critical application of the classification system and to highlight the clinical implications of the imaging findings. ^©RSNA, 2017.

Interprosthetic and Peri-Implant Fractures: Principles of Operative Fixation and Future Directions

Advances in medicine and orthopaedic implant technology have dramatically increased the number of patients sustaining interprosthetic, inter-, or peri-implant fractures. For these complex clinical scenarios, there are currently no available treatment algorithms. In this review, we outline the principles, strategies, and techniques to obtain both successful reconstruction and maximum function.

LEVEL OF EVIDENCE

Therapeutic Level V. See Instructions for Authors for a complete description of levels of evidence.

Plate Positioning in Periprosthetic or Interprosthetic Femur Fractures With Stable Implants-A Biomechanical Study

BACKGROUND

Angular stable plate fixation is a widely accepted treatment option for interprosthetic or periprosthetic femoral fractures with stable implants. This biomechanical study tries to establish a safe distance of the plate from the tip of a femoral prosthesis.

METHODS

A total of 38 composite femurs were reamed to an inner diameter of 23 mm to create an osteoporotic bone model. A Weber hip stem was cemented into each and a distal femoral NCB plate applied with the distance to the stem varying from 8 cm apart to 6 cm overlap in 2-cm steps. Each specimen was tested in cyclic axial loading (400 N-1500 N) and then cyclic torsion (0.6 Nm-50 Nm). Peak strain on the femur around the tip of the plate was measured with a 3D image correlation system and averaged over 26 cycles (excluding the first 3 and the last cycles). Finally, each femur was axially loaded to failure.

RESULTS

Strain increased with decreasing overlap or gap. Seven specimens failed early between 2-cm overlap and 2-cm gap. Results were divided into a far group with a distance of >4 cm and a close group of <4 cm. Strain was significantly higher in the close group for axial (P < .001) and torsional (P < .001) loading. Failure load was significantly lower in the close group (P = .002).

CONCLUSION

A minimal gap and/or overlap of at least 6 cm is recommended in osteoporotic bone to avoid stress risers.