The effect of strut allograft and its position on Vancouver type B1 periprosthetic femoral fractures: a biomechanical study

A New System for Periprosthetic Fracture Stabilization-A Biomechanical Comparison

In recent years, an increase in periprosthetic femur fractures has become apparent due to the increased number of hip replacements. In the case of Vancouver type B1 fractures, locking plate systems offer safe procedures. This study compared the distal lateral femur plate (LOQTEQ^®, aap Implantate AG) with a standard L.I.S.S. LCP^® (DePuy Synthes) regarding their biomechanical properties in fixation of periprosthetic femur fractures after hip arthroplasty. We hypothesized that the new LOQTEQ system has superior stability and durability in comparison. Eighteen artificial left femurs were randomized in two groups (Group A: LOQTEQ^®; Group B: L.I.S.S. LCP^®) and tested until failure. Failure was defined as 10° varus deformity and catastrophic implant failure (loosening, breakage, progressive bending). Axial stiffness, loads of failure, cycles of failure, modes of failure were recorded. The axial stiffness in Group A with 73.4 N/mm (SD +/− 3.0) was significantly higher (p = 0.001) than in Group B (40.7 N/mm (SD +/− 2.8)). Group A resists more cycles than Group B until 10° varus deformity. Catastrophic failure mode was plate breakage in Group A and bending in Group B. In conclusion, LOQTEQ^® provides higher primary stability and tends to have higher durability.

Combined Surgical and Medical Treatment for Vancouver B1 and C Periprosthetic Femoral Fractures: A Proposal of a Therapeutic Algorithm While Retaining the Original Stable Stem

INTRODUCTION

There is lack of consensus regarding best operative fixation strategy for periprosthetic femoral fractures (PFFs) around a stable stem. Evidence exists that some patterns of fracture around a stable stem are better treated with revision surgery than with standard fixation. Anyway, a more aggressive surgical procedure together with medical treatment could allow for stem retention, and reduced risk of nonunion/hardware failure, even in these cases.

SIGNIFICANCE

This paper is placed in a broader context of lack of studies on the matter, and its aim is to shed some light on the management of PFFs around a stable stem, when peculiar mechanical and biological aspects are present.

RESULTS

Based on our casuistry in the treatment of nonunions after PFF successfully treated with original stem retention, and on review of Literature about risk factors for fixation failure, an algorithm is proposed that can guide in choosing the ideal surgical technique even for first-time PFFs with a stable stem, without resorting to revision. Mechanical (major and minor) and biological (local and systemic) factors that may influence fracture healing, leading to nonunion and hardware failure, and subsequent need for re-operation, are considered. The proposed surgical technique consists of rigid fixation with absolute stability (using a plate and structural allograft) plus local biological support (structural allograft and autologous bone marrow concentrate over a platelet-rich plasma-based scaffold) at fracture site. Systemic anabolic treatment (Teriparatide) is also administered in the post-operative period.

CONCLUSION

Mechanical factors are not the only issues to be considered when choosing the surgical approach to PFFs over a stable stem. Systemic and local biological conditions should be taken into account, as well. A therapeutic algorithm is proposed, given the prosthetic stem to be stable, considering mechanical and biological criteria.

Periprosthetic hip fractures: an update into their management and clinical outcomes

The Vancouver classification is still a useful tool of communication and stratification of periprosthetic fractures, but besides the three parameters it considers, clinicians should also assess additional factors.

Combined advanced trauma and arthroplasty skills must be available in departments managing these complex injuries.

Preoperative confirmation of the THA (total hip arthroplasty) stability is sometimes challenging. The most reliable method remains intraoperative assessment during surgical exploration of the hip joint.

Certain B1 fractures will benefit from revision surgery, whilst some B2 fractures can be effectively managed with osteosynthesis, especially in frail patients.

Less invasive osteosynthesis, balanced plate–bone constructs, composite implant solutions, together with an appropriate reduction of the limb axis, rotation and length are critical for a successful fixation and uneventful fracture healing.

Cite this article: EFORT Open Rev 2021;6:75-92. DOI: 10.1302/2058-5241.6.200050

Onlay fibula autografting technique and its comparison with cortical allograft for the reconstruction of periprosthetic bone defects around the femur

BACKGROUND

Bone defect around the femur related to revisions or periprosthetic fractures (PFF) is an issue. We present a bone defect reconstruction technique in femoral revisions and/or PFF using fibula autograft and compared our radiological and clinical results to that of allograft.

METHODS

A total of 53 patients who underwent revision hip arthroplasty and/or PFF fixation with the use of cortical fibula autograft (FG group) or cortical allograft (CG group) were evaluated. After exclusions, 20 patients who had minimum two years of follow-up were investigated for each group, for their radiological and clinical outcomes.

RESULTS

In FG and CG groups, the median ages were 69.5(44-90) and 62(38-88) years, follow-ups were 59(28-72) and 120(48-216) months, defect lengths were seven (1-10) and ten (1-17) cm, and grafts lengths were 16.5(10-30) and 20(12-37) cm, respectively. The rate of graft incorporation was 90% in each group and median time to incorporations were seven (4-12) and 12(6-24) months (p < 0.001), and graft resorption (moderate and severe) rates were 10% and 25% (p = 0.41), respectively. Median Harris Hip (77.6 vs 78.0), WOMAC (23.2 vs 22), SF-12 physical (50.0 vs 46.1), and SF-12 mental (53.8 vs 52.5) scores were similar between the groups, respectively. Kaplan-Meier survivorship analyses revealed an estimated mean survival of 100% at six years in FG group and 90% at 14 years in CG group.

CONCLUSION

In the reconstruction of periprosthetic bone defects after femoral revision or PPF, onlay cortical fibula autografts provide comparable clinical and radiological outcomes to allografts. Its incorporation is faster, it is cost-effective and easy to obtain without apparent morbidity.

Bone restoration after revision hip arthroplasty with femoral bone defects using extensively porous-coated stems with cortical strut allografts

Background

Stress shielding and bone loss of the femur are of great concern after revision total hip arthroplasty (THA) with extensively porous-coated stems, especially in a femur with already bone loss. The femoral bone remodeling patterns after revision THA with femoral bone defects using extensively porous-coated stems with cortical strut allografts remain unclear.

Methods

We retrospectively reviewed 47 patients who underwent revision THA using extensively porous-coated stems combined with cortical strut allografts and 75 patients without allografts. The minimum follow-up was 2 years. Femoral bone remodeling signs, including stress shielding, bone restoration in bone defect area, distal cortical hypertrophy, and femoral width, were compared between patients with and without cortical strut allografts. Clinical outcomes were also compared between two groups.

Results

Patients with cortical strut allografts showed less severe stress shielding (P = 0.01) than patients without allografts. Patients with allografts had more osseous restoration in bone defect area than patients without allografts (63.8% vs 30.7%, P < 0.001). Femoral width was significantly higher in femur with allografts than in femur without allografts at the immediate postoperative stage and latest follow-up (both P < 0.001). The hip function score, re-revision rate, and complications were comparable between two groups.

Conclusion

The application of cortical strut allografts can decrease the severity of stress shielding, augment osseous restoration in bone defect area and improve femoral bone stock after revision THA using extensively porous-coated stems.

Association of the Anterolateral Thigh Osteomyocutaneous Flap With Femur Structural Integrity and Assessment of Prophylactic Fixation

Importance

The chimeric anterolateral thigh osteomyocutaneous (ALTO) free flap is a recently described microvascular option for head and neck osseous defects associated with complex soft-tissue requirements. To date, the association of ALTO flap harvest with femur structural integrity and the need for routine prophylactic fixation following harvest has been incompletely described.

Objective

To investigate the association of ALTO flap harvest, with and without prophylactic fixation, on femur structural integrity as measured by 4-point bend and torsional biomechanical testing.

Design and Setting

At a research laboratory, 24 synthetic fourth-generation composite femurs with validated biomechanical properties underwent 10-cm-long, 30% circumferential osteotomies at the proximal middle third of the femur; 6 femurs served as controls. Osteotomized femurs with and without fixation underwent torsional and 4-point bend biomechanical testing. Femur fixation consisted of intramedullary nail and distal interlock screw placement.

Main Outcomes and Measures

Force and torque to fracture (expressed in kilonewtons [kN] and Newton meters [N∙m], respectively) were compared between controls, osteotomized femurs without fixation, and osteotomized femurs with fixation. Additional outcome measures included femur stiffness and fracture patterns.

Results

On posterior to anterior (PA) 4-point bend testing, force to fracture of osteotomized femurs was 22% of controls (mean difference, 8.3 kN; 95% CI, 6.6-10.0 kN). On torsional testing the torque to fracture of osteotomized femurs was 12% of controls (mean difference, 351.1 N∙m; 95% CI, 307.1-395.1 N∙m). Following fixation there was a 67% improvement in PA force to fracture and a 37% improvement in torque to fracture. However, osteotomized femurs with fixation continued to have a reduced PA force to fracture at 37% of controls (mean difference, 6.8 kN; 95% CI, 4.5-9.2 kN) and torque to fracture at 16% of controls (mean difference, 333.7 N∙m; 95% CI, 306.8-360.6 N∙m). On torsional testing, all osteotomized femurs developed similar spiral fractures through a corner of the distal osteotomy site. This fracture pattern changed after prophylactic fixation with femurs developing nondisplaced fractures through the proximal osteotomy site. There were no underlying hardware failures during testing of osteotomized femurs with fixation.

Conclusions and Relevance

Anterolateral thigh osteomyocutaneous flap harvest results in significant changes in the structural integrity of the femur. Postoperative stabilization should be strongly considered, with future research directed at investigating the clinical significance of residual biomechanical changes following femur fixation.

Periprosthetic fracture fixation of the femur following total hip arthroplasty: A review of biomechanical testing - Part II

BACKGROUND

Periprosthetic femoral fracture is a severe complication of total hip arthroplasty. A previous review published in 2011 summarised the biomechanical studies regarding periprosthetic femoral fracture and its fixation techniques. Since then, there have been several commercially available fracture plates designed specifically for the treatment of these fractures. However, several clinical studies still report failure of fixation treatments used for these fractures.

METHODS

The current literature on biomechanical models of periprosthetic femoral fracture fixation since 2010 to present is reviewed. The methodologies involved in the experimental and computational studies of periprosthetic femoral fracture fixation are described and compared with particular focus on the recent developments.

FINDINGS

Several issues raised in the previous review paper have been addressed by current studies; such as validating computational results with experimental data. Current experimental studies are more sophisticated in design. Computational studies have been useful in studying fixation methods or conditions (such as bone healing) that are difficult to study in vivo or in vitro. However, a few issues still remain and are highlighted.

INTERPRETATION

The increased use of computational studies in investigating periprosthetic femoral fracture fixation techniques has proven valuable. Existing protocols for testing periprosthetic femoral fracture fixation need to be standardised in order to make more direct and conclusive comparisons between studies. A consensus on the 'optimum' treatment method for periprosthetic femoral fracture fixation needs to be achieved.

Cable plating with a single strut allograft in the treatment of periprosthetic fractures of the femur

BACKGROUND:

Hip arthroplasties are increasing worldwide resulting in an increasing number of periprosthetic fractures. These fractures are difficult to treat with various the different fixation or revision options described, many of which have high complication rates.

PURPOSE:

To investigate whether our described method of treating periprosthetic fractures is an effective, safe and reproducible method of treating patients.

METHODS:

We describe the largest series of a cable plate fixation system combined with a single cortical strut allograft to treat patients with periprosthetic fractures of the hip (Unified Classification System B1 and selected B2, C and D).

RESULTS:

Between July 2006 and March 2015, 28 patients were treated using this method. The mean follow-up was 2.2 years (3 months to 9 years). The mean Oxford Hip Score (OHS) at final follow-up was 32 and the mean modified Harris Hip Score (mHHS) 67. There were 3 complications including 1 failure that required revision surgery, 1 case of infection successfully treated with debridement, antibiotics and retention, and a case of discomfort from the metalwork which we managed conservatively.

CONCLUSION:

This method of anatomical restoration of the femur with dual-plane fixation is a highly effective method of treating this complex group of patients, and should be considered as a first line of treatment. It shows that there is a role for successful treatment with internal fixation of certain B2, C and D fractures with this technique.

Biomechanical Evaluation of Osteoporotic Proximal Periprosthetic Femur Fractures With Proximal Bicortical Fixation and Allograft Struts

OBJECTIVES

To evaluate the strength of proximal bicortical fixation using a novel osteoporotic synthetic bone model of Vancouver B1 periprosthetic proximal periprosthetic femur fractures (PFFs) and to assess the influence of strut allograft augmentation with regard to allowing early assisted weight bearing. The secondary aim was to evaluate whether the strut position, either medial or anterior, influenced the strength of the construct.

METHODS

Thirty synthetic osteoporotic femurs were implanted with cemented stems. A segmental defect made distal to the stem simulated a fracture and was repaired with a stainless steel locking compression plate and 2 stainless steel proximal locking attachment plates. Specimens were then divided into 3 groups: no-strut, medial strut, and anterior strut. Cadaveric femoral struts were wired to the specimens. Cyclic axial compression simulated assisted weight bearing and was followed by loading to failure.

RESULTS

Medial struts required higher failure load than no-strut (P = 0.008) and more energy to failure than anterior (P = 0.018) or no-strut (P < 0.001). The higher load to failure, however, would not be advantageous in clinical practice because estimates for assisted weight bearing after fractures in average-weight patients are well below these failure loads. Furthermore, all specimens tolerated cyclical loading. All failures occurred distal to the plate originating at the last screw hole.

CONCLUSIONS

Failure loads for all groups were above what would be expected for low-demand activities of assisted weight bearing. Therefore, proximal bicortical fixation should allow for early, assisted weight bearing without allograft strut augmentation even with lower density bone.

A methodology for the generation and non-destructive characterisation of transverse fractures in long bones

Long bone fractures are common and although treatments are highly effective in most cases, it is challenging to achieve successful repair for groups such as open and periprosthetic fractures. Previous biomechanical studies of fracture repair, including computer and experimental models, have simplified the fracture with a flat geometry or a gap, and there is a need for a more accurate fracture representation to mimic the situation in-vivo. The aims of this study were to develop a methodology for generating repeatable transverse fractures in long bones in-vitro and to characterise the fracture surface using non-invasive computer tomography (CT) methods. Ten porcine femora were fractured in a custom-built rig under high-rate loading conditions to generate consistent transverse fractures (angle to femoral axis < 30 degrees). The bones were imaged using high resolution peripheral quantitative CT (HR-pQCT). A method was developed to extract the roughness and form profiles of the fracture surface from the image data using custom code and Guassian filters. The method was tested and validated using artificially generated waveforms. The results revealed that the smoothing algorithm used in the script was robust but the optimum kernel size has to be considered.

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A new method to generate and quantify long bone fracture surface geometry is proposed.

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Reliable transverse fractures were generated and imaged using microCT.

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A non-destructive method to characterise the surface from the images was developed

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Validation of the method using benchmark waveforms showed the method to be robust

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By tuning the filtering conditions, specific characteristics of the surface can be extracted.

An international, cross-sectional survey of the management of Vancouver type B1 periprosthetic femoral fractures around total hip arthroplasties

INTRODUCTION

The incidence of periprosthetic femoral fractures around total hip arthroplasties is increasing. Fractures around a stable implant stem (Vancouver type B1) are among the most common of these fractures. Various fixation strategies for Vancouver type B1 periprosthetic fractures have been reported in the literature; however, little high-level evidence exists. This study was designed to determine the current management strategies and opinions among orthopaedic surgeons treating Vancouver type B1 periprosthetic femoral fractures, and to evaluate the need for a large prospective randomized controlled trial for the management of these injuries.

METHODS

Orthopaedic surgeon members of the Orthopaedic Trauma Association (OTA), the Canadian Orthopaedic Association (COA), and the Hip Society were invited to participate in a 51-item web-based survey surrounding the management of periprosthetic femoral fractures around total hip replacements, as well as the perceived need for future research in this area. Responses were summarized using proportions, and further stratified by practice type, case volume, surgeon age, and fellowship training.

RESULTS

For Vancouver type B1 fractures, open reduction and internal fixation (ORIF) with locked plating was favoured slightly over ORIF with cable plating ± cortical strut allograft (51.1% versus 45.5%). When compared to cable plating with cortical strut allograft, respondents believed that isolated locked plating resulted in lower nonunion and reoperation rates, but similar infection and malunion rates. Subgroup analyses revealed that practice type, surgeon age, case volume, and fellowship training influenced surgeons' management of periprosthetic femoral fractures and beliefs regarding complications. There is high demand for a large prospective randomized controlled trial for Vancouver type B1 fracture fixation.

CONCLUSIONS

Consensus surrounding the management of Vancouver type B1 periprosthetic femoral fractures is lacking, and there is a perceived need among orthopaedic surgeons for a large prospective randomized controlled trial in order to define the optimal management of these injuries.

High union rates of locking compression plating with cortical strut allograft for type B1 periprosthetic femoral fractures

PURPOSE

Unified classification system (UCS) type B1 periprosthetic femoral fractures are associated with many complications, and management decisions continue to be controversial. The purpose of this study was to evaluate outcomes of UCS type B1 periprosthetic femoral fractures treated by locking compression plating with strut allograft augmentation.

MATERIALS AND METHODS

We retrospectively reviewed 17 consecutive UCS type B1 periprosthetic femoral fractures treated by open reduction and internal fixation using a lateral locking compression plate supplemented with an anterior cortical strut allograft. There was one man and 16 women with an average age of 74 years (range, 57-92 years). All had a cementless hip arthroplasty, and eight of the arthroplasties were revisions.

RESULTS

The mean duration of follow-up was 28 months (range, 12-74 months). All 17 fractures healed successfully at a mean of 20 weeks (range, 12-30 weeks). The mean post-operative Harris hip score was 86 points (range, 77-95 points). No mechanical complications such as failure of plate or screws and malalignment were noted. According to the graft-remodeling classification of Emerson et al., a partial bridging was observed in nine and a complete bridging in eight. Two patients required a removal of the plate due to irritation of the iliotibial band. No femoral stem loosening or deep infection was observed.

CONCLUSION

Our findings indicate that open reduction and internal fixation of UCS type B1 periprosthetic femoral fractures using a lateral locking compression plate supplemented with anterior cortical strut allograft provides adequate mechanical stability of fracture fixation and enhances the fracture healing.

Biomechanical comparison of oblique and step-cut osteotomies used in total hip arthroplasty with femoral shortening

BACKGROUND

Various types of shortening osteotomies and prosthesis are used for femoral reconstruction in total hip arthroplasty of the high hip dislocation. This biomechanical study investigates whether step-cut osteotomies result in better stability than oblique osteotomies and cylindrical femoral stems enhance stability of the osteotomy more than conical stems, and which osteotomy and prosthesis type maintain the stability better after cyclical loading.

METHODS

Oblique and step-cut shortening osteotomies were compared under axial and rotational forces, using synthetic femur models and conical or cylindrical femoral prostheses. The models underwent cyclic loading for 10,000 cycles at 3 Hz (100-1000 N axial bending or 0.5-10 Nm torque). After the completion of cyclic loading, the models were loaded until failure. Stiffness values before and after cyclical loading, and failure loads were the outcome parameters. Relative displacements at the osteotomy sites were also measured using 3-Dimensions Digital Imaging Correlation System.

RESULTS

The mean failure load was significantly higher in conical prosthesis groups under axial forces. In torsion tests, the mean stiffness of conical prosthesis groups after cyclical loading was higher in oblique osteotomies. The other parameters were similar between the groups.

CONCLUSIONS

According to the results of the study, although some individual statistically significant parameters were obtained, step-cut osteotomies, which are technically challenging procedures, were not found biomechanically superior to oblique osteotomies, with neither conical nor cylindrical prostheses.

Application of Far Cortical Locking Technology in Periprosthetic Femoral Fracture Fixation: A Biomechanical Study

BACKGROUND

Lack of fracture movement could be a potential cause of periprosthetic femoral fracture (PFF) fixation failures. This study aimed to test whether the use of distal far cortical locking screws reduces the overall stiffness of PFF fixations and allows an increase in fracture movement compared to standard locking screws while retaining the overall strength of the PFF fixations.

METHODS

Twelve laboratory models of Vancouver type B1 PFFs were developed. In all specimens, the proximal screw fixations were similar, whereas in 6 specimens, distal locking screws were used, and in the other six specimens, far cortical locking screws. The overall stiffness, fracture movement, and pattern of strain distribution on the plate were measured in stable and unstable fractures under anatomic 1-legged stance. Specimens with unstable fracture were loaded to failure.

RESULTS

No statistical difference was found between the stiffness and fracture movement of the two groups in stable fractures. In the unstable fractures, the overall stiffness and fracture movement of the locking group was significantly higher and lower than the far cortical group, respectively. Maximum principal strain on the plate was consistently lower in the far cortical group, and there was no significant difference between the failure loads of the 2 groups.

CONCLUSION

The results indicate that far cortical locking screws can reduce the overall effective stiffness of the locking plates and increase the fracture movement while maintaining the overall strength of the PFF fixation construct. However, in unstable fractures, alternative fixation methods, for example, long stem revision might be a better option.

Biomechanical Comparison of 2 Different Femoral Stems in the Shortening Osteotomy of the High-Riding Hip

BACKGROUND

We hypothesized that a rectangular cross-sectional femoral stem may produce more initial stability of the transverse subtrochanteric femoral shortening osteotomy rather than a circular cross-sectional stem.

METHODS

Twenty, fourth-generation, synthetic femur models were inserted with either circular or rectangular cross-sectional femoral stems after 3 cm of transverse subtrochanteric shortening. Half of the models were tested with axial bending and the other half with torsional loads. After the femora underwent cyclic loading, they were loaded until failure. Outcome parameters were stiffness values before and after cyclical loading, failure loads/torques, and displacements at the osteotomy sites.

RESULTS

In axial bending tests, the results were not significantly different between the groups. Under rotational forces, the mean stiffness value before cyclical loading and failure torque of the cylindrical stems was significantly higher than that of rectangular cross-sectional stems (11.8 ± 1.2 vs 7.1 ± 2.8 Nm/degree; P = .009 and 136.9 ± 60.2 vs 27.1 ± 17.5 Nm; P = .027 Nm, respectively). The mean amounts of displacements at the osteotomy sites were not significantly different between the groups in any direction in both axial and rotational tests.

CONCLUSIONS

According to the results of the study, using straight, cylindrical femoral stems can increase rotational stability of the transverse osteotomy more than the rectangular cross-sectional stems although the latter one has the advantages of rectangular geometrical design.

Biomechanical Concepts for Fracture Fixation

Application of the correct fixation construct is critical for fracture healing and long-term stability; however, it is a complex issue with numerous significant factors. This review describes a number of common fracture types and evaluates their currently available fracture fixation constructs. In the setting of complex elbow instability, stable fixation or radial head replacement with an appropriately sized implant in conjunction with ligamentous repair is required to restore stability. For unstable sacral fractures with vertical or multiplanar instabilities, "standard" iliosacral screw fixation is not sufficient. Periprosthetic femur fractures, in particular Vancouver B1 fractures, have increased stability when using 90/90 fixation versus a single locking plate. Far cortical locking combines the concept of dynamization with locked plating to achieve superior healing of a distal femur fracture. Finally, there is no ideal construct for syndesmotic fracture stabilization; however, these fractures should be fixed using a device that allows for sufficient motion in the syndesmosis. In general, orthopaedic surgeons should select a fracture fixation construct that restores stability and promotes healing at the fracture site, while reducing the potential for fixation failure.

Periprosthetic femoral fractures: When I use strut grafts and why?

Cortical onlay strut allografts, as the primary method of fixation or as a supplementary fixation when a plate is used, have been a common option to treat B1 and C type PFF in the past decades since the technique was described by Penenberg et al. in 1989. Strut grafts were described as a useful treatment option because they provide structural support to the internal fixation while increasing the host bone stock without the harvesting complications. However, the use of struts have some concerns such as if the soft tissue stripping required for its application may lead into a delayed bone healing or increase the infection rate. Other concerns are the role as disease carrier, immune reactions, incorporation to the host bone in the long term and, in some centres, the availability and costs. This article reviews the literature regarding the use of struts in PFF and provides an overview on the use of strut grafts with actual recommendations based on the authors experience and the data from literature.

Periprosthetic femoral fracture fixation: a biomechanical comparison between proximal locking screws and cables

BACKGROUND

The incidence of periprosthetic femoral fractures (PFF) around a stable stem is increasing. The aim of this biomechanical study was to examine how three different methods of fixation, for Vancouver type B1 PFF, alter the stiffness and strain of a construct under various configurations, in order to gain a better insight into the optimal fixation method.

METHODS

Three different combinations of proximal screws and Dall-Miles cables were used: (A) proximal unicortical locking screws alone; (B) proximal cables and unicortical locking screws; (C) proximal cable alone, each in combination with distal bicortical locking screws, to fix a stainless steel locking compression plate to five synthetic femora with simulated Vancouver type B1 PFFs. In one synthetic femora, there was a 10-mm fracture gap, in order to simulate a comminuted injury. The other four femora had no fracture gap, to simulate a stable injury. An axial load was applied to the constructs at varying degrees of adduction, and the overall construct stiffness and surface strain were measured.

RESULTS

With regards to stiffness, in both the gap and no gap models, method of fixation A was the stiffest form of fixation. The inclusion of the fracture gap reduced the stiffness of the construct quite considerably for all methods of fixation. The strain across both the femur and the plate was considerably less for method of fixation C, compared to A and B, at the locations considered in this study.

CONCLUSION

This study highlights that the inclusion of cables appears to damage the screw fixations and does not aid in construct stability. Furthermore, the degree of fracture reduction affects the whole construct stability and the bending behaviour of the fixation.

Periprosthetic fractures: bespoke solutions

We are currently facing an epidemic of periprosthetic fractures around the hip. They may occur either during surgery or post-operatively. Although the acetabulum may be involved, the femur is most commonly affected. We are being presented with new, difficult fracture patterns around cemented and cementless implants, and we face the challenge of an elderly population who may have grossly deficient bone and may struggle to rehabilitate after such injuries. The correct surgical management of these fractures is challenging. This article will review the current choices of implants and techniques available to deal with periprosthetic fractures of the femur.

The management of type B1 periprosthetic femoral fractures: when to fix and when to revise

The incidence of periprosthetic fractures around total hip arthroplasty is increasing as patient longevity rises and the number of patients with hip implants continues to grow. Type B1 periprosthetic femoral fractures are associated with a well-fixed stem and have traditionally been treated with internal fixation. However, there are a subset of these fractures which fare badly when internal fixation is undertaken, and revision of the femoral component to a long-stemmed implant may be more appropriate. We look at the traditional methods of fixation, and the evidence and indications for revision of these fractures.