Periprosthetic fracture fixation in osteoporotic bone

Comparing the Biomechanical Stability of Cerclage Cable with Plate Insert Versus Locking Screw in Periprosthetic Humeral Fracture

BACKGROUND

In the setting of periprosthetic humeral fractures, the humeral stem of the implant represents a substantial challenge to the optimal method of proximal fixation. This study aimed to compare the initial biomechanical stability provided by cerclage cables with a locking plate insert versus bicortical locking screws (i.e., the gold standard for fixation) in fresh cadaveric humeri.

METHODS

After calculating the sample size, we utilized 10 sets of cadaveric specimens and created a 5-mm osteotomy gap 120 mm distal to the tip of the greater tuberosity, simulating a Wright and Cofield type-B periprosthetic humeral fracture on each specimen. Using 3 locking screws for distal fragment fixation, identical in all specimens, the specimens were assigned to Group A (3 cerclage cables with a plate insert) or Group B (3 locking bicortical screws) for proximal fragment fixation. Biomechanical tests included stiffness in varus and valgus bending, torsion, and axial compression, and a single load to failure.

RESULTS

No significant differences were observed in the biomechanical metrics between the 2 groups.

CONCLUSIONS

Our study revealed that fixation with use of cerclage cables with a plate insert demonstrated biomechanical stability comparable with that of bicortical locking screw fixation when addressing the proximal fragment in Wright and Cofield type-B periprosthetic humeral fractures.

CLINICAL RELEVANCE

For proximal fragment fixation of periprosthetic humeral fractures, cerclage cables with a plate insert can be utilized as an effective fixation method that offers initial fixation strength that is comparable to the use of 3 locking bicortical screws.

Open the pores - Polydimethylsiloxane influences the porous structure of cancellous bone surrogates for biomechanical testing of osteosyntheses

Synthetic materials used for valid and reliable implant testing and design should reflect the mechanical and morphometric properties of human bone. Such bone models are already available on the market, but they do not reflect the population variability of human bone, nor are they open-celled porous as human bone is. Biomechanical studies aimed at cementing the fracture or an implant cannot be conducted with them. The aim of this study was to investigate the influence of a cell stabilizer on polyurethane-based cancellous synthetic bone in terms of morphology, compressive mechanics, and opening of the cancellous bone structure for bone cement application. Mechanical properties of cylindrical specimens of the bone surrogates were determined by static compression tests to failure. Furthermore, a morphometric analysis was performed using microcomputed tomography. To prove the open-cell nature of the bone surrogates, an attempt was made to apply bone cement. Effects on the mechanical properties of the polyurethane-based bone surrogates were observed by the addition of polydimethylsiloxane. All mechanical parameters like Young's modulus, ultimate stress and yield stress increased statistically significantly with increasing amounts of cell stabilizer (all p > 0.001), except for yield stress. The analysis of morphometric parameters showed a decrease in trabecular thickness, spacing and connectivity density, which was accompanied by an increase in trabecular number and an increase in pore size. The open-cell nature was proven by the application and distribution of bone cement in specimens with stabilizer, which was visualized by X-ray. In conclusion, the results show that by adding a cell stabilizer, polyurethane-based cancellous bone substrates can be produced that have an open-cell structure similar to human bone. This makes these bone surrogates suitable for biomechanical testing of osteosyntheses and for osteosynthesis cementation issues.

Prehabilitation in a Periprosthetic Fracture of the Femur: A Case Report

Periprosthetic fractures (PPF) are related to orthopaedic implants like internal fixators, replacement devices, etc. In this case report, we discussed a 55-year-old male patient who came to our tertiary care hospital with complaints of pain and swelling over the left hip for six months. After radiological investigations, he was diagnosed with a left PPF of the femur with posterior dislocation. He was referred to the musculoskeletal physiotherapy department for in-patient rehabilitation before surgery. He received strengthening exercises for lower limb, back, and abdominal muscles, pain management, gait training, etc. for two weeks before his decided surgery date. The patient showed improved strength and maintained his range. There were an improved Visual Analogue Scale (VAS) score and a Lower Extremity Functional Scale (LEFS) score, which signified a reduction in pain and improved functional independence due to enhanced lower limb function, respectively.

Addressing osteoporosis treatment after hemiarthroplasty for a femoral neck fracture: impact on survival rates after a subsequent periprosthetic femoral fracture - a multicenter (TRON group) retrospective study

This study investigated the impact of osteoporosis treatment on the prognosis of patients with periprosthetic femoral fracture (PPF) following femoral neck fracture (FNF). Our results suggested an association between osteoporosis treatment and potentially improved survival prognosis in patients who underwent surgery for PPF. These results imply that osteoporosis treatment may have a beneficial effect on patient outcomes.

PURPOSE

This study aimed to investigate the effect of osteoporosis treatment on the prognosis of periprosthetic femoral fracture (PPF) patients after femoral neck fracture.

METHODS

A multicenter retrospective study named as TRON was conducted. The study population included 156 PPF patients who had undergone hemiarthroplasty for femoral neck fracture between January 2010 and December 2019. Patients were divided based on whether they had received osteoporosis treatment before PPF injury. A log-rank test was used to compare survival rates. We conducted a Cox proportional hazards analysis to identify factors associated with the survival rate after PFF injury.

RESULTS

Twenty-seven of the 156 patients had received osteoporosis treatment prior to PPF injury. The 1-year and 2-year overall survival rates after PPF were 80.9% and 75.3%, respectively. The log-rank test revealed that the 1-year survival rate with and without osteoporosis treatment was 89.5% and 78.1%, respectively (P=0.012). In the Cox proportional hazards analysis, age, BMI, presence or absence of surgery, and presence or absence of osteoporosis treatment showed independent associations with the survival rate after PFF injury. The hazard ratio for the presence of osteoporosis treatment was 0.22 (95% confidence interval 0.07-0.75, P=0.015).

CONCLUSION

The findings of this study suggest an association between osteoporosis treatment and potentially improved survival prognosis in patients who underwent surgery for PPF. These results imply that osteoporosis treatment may have a beneficial effect on patient outcomes. It is important to consider that osteoporosis treatment could be significant not only in preventing secondary fractures but also in potentially improving prognosis in the rare event of PPF.

Femoral periprosthetic fracture treatment using the Ortho-Bridge System: a biomechanical study

BACKGROUND

We undertook a comparative biomechanical study of type B1 fractures around femoral prostheses following cemented hip arthroplasty using the Ortho-Bridge System (OBS) and a locking compression plate/locking attachment plate structure (LCP + LAP). We aimed to investigate the biomechanical characteristics and advantages of the OBS compared with LCP + LAP when treating this fracture type.

METHODS

An OBS fixation model was designed based on OBS and LCP + LAP fixation characteristics. The LCP + LAP combination (Group A) and three different OBS combinations (Groups B, C, and D) were used to fix a B1 fracture model with a femoral periprosthetic fracture. Axial compression and torsion experiments were then performed using simple and comminuted fracture models. The axial compression failure experiment was carried out, and the model stiffness during axial compression, torsion angle in torsion test, and vertical load in the final failure test were collected.

RESULTS

When simulating simple oblique fractures, no significant difference was found among the four groups in terms of stiffness in the axial compression experiment (P = 0.257). The torsion angle of the LCP + LAP system was significantly higher compared with the OBS system (P < 0.05). When simulating a comminuted fracture, the experimental data for axial compression showed that the rigidity measurements of the three combinations of the OBS system were higher compared with the LCP + LAP system (P = 0.000) and that the torsion angles of three combinations of the OBS system were smaller compared with the LCP + LAP system (P < 0.05). In the axial compression failure test, the fixed failure mode of the LCP + LAP system was the destruction of the contact cortex at the fracture site, whereas the failure modes in the three OBS combinations involved fracture around the screws above the osteotomy and destruction of the contact cortex at the fracture site.

CONCLUSIONS

The findings revealed that the OBS produced superior biomechanical outcomes compared with LCP + LAP, especially for the bridging two-rod dual cortex. According to the performance observed after model axial compression destruction, the OBS was fixed and provided greater stress dispersion, which might make it more suitable for facilitating early functional movement and avoiding the failure of internal fixation.

Fragility Fractures of the Acetabulum: Current Concepts for Improving Patients' Outcomes

The incidence of fragility fractures of the acetabulum (FFA) is constantly increasing. Generally, these fractures are related to a fall on the greater trochanter involving the anterior column. The management of FFA is extremely difficult considering both patients' comorbidities and poor bone quality. Both non-operative and several operative treatment protocols are available, and the choice among them is still ambiguous. The proposed surgical techniques for FFA [namely open reduction and internal fixation (ORIF), percutaneous fixation and total hip arthroplasty (THA)] are associated with a high complication rate. The treatment with the higher early mortality is the ORIF + THA, while the one with the lowest is the non-operative. However, at longer follow-up, this difference dreadfully change is becoming the opposite. Frequently ORIF, percutaneous fixation, and non-operative treatment need a subsequent re-operation through a THA. This latter could be extremely difficult, because of poor bone quality, acetabular mal union/non-union, bone gaps and hardware retention. However, the outcomes of each of the proposed treatment are mostly poor and controverted; therefore, a comprehensive patient evaluation and an accurate fracture description are required to appropriately manage acetabular fracture in the elderly.

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.

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.

Periprosthetic fracture fixation in Vancouver B1 femoral shaft fractures: A biomechanical study comparing two plate systems

Introduction

Periprosthetic fractures of the femur are an increasing problem in today's trauma and orthopaedic surgery. Owing to the hip stem, implant anchorage is very difficult in the proximal femur. This study compares two plate systems regarding their biomechanical properties and the handling in periprosthetic fracture fixation of the proximal femur.

Materials and methods

Using eight pairs of fresh, frozen human proximal femora the Locking Compression Plate/Locking Attachment Plate construct (LCP/LAP) (group I, DePuy Synthes) was compared to the new LOQTEQ® periprosthetic distal lateral femur plate (group II, AAP Implantate AG). After implantation of press fit femoral hip stems a Vancouver B1 fracture model was used. Biomechanical testing was performed by cyclic axial loading with a constant increment of 0.1 N/cycle starting from 750 N axial loading. Every 250 cycles an a.p. x-ray was done to evaluate failure.

Results

The Group II showed significant higher axial stiffness (+42%) compared with Group I. In addition, Group II withstood significantly more load-cycles until failure (20%). The mode of catastrophic failure was plate breakage in Group II, whereas, in Group I, all plates showed an early bending followed by plate breakage.

Discussion and conclusion

Both plate systems enable screw placement around hip stems. The hinge plate showed superior biomechanical results compared with the locking compression plate/locking attachment plate construct. Furthermore, the hinge plate offers variable hinges and variable angel locking making bicortical screw placement around hip stems more comfortable and safe.

The translational potential of this article

The results of this study can be directly transferred to patient care. With the innovative hinge plate, the surgeon has a biomechanically superior implant, which also offers improved options for screw placement compared to a standard locking plate.

[Periprosthetic fractures: basics, classification and treatment principles]

Periprosthetic fractures (PPFx) are becoming an increasingly important topic in orthopedics and trauma surgery due to the rising number of endoprosthetic joint replacements. The recently published unified classification system (UCS) has replaced numerous historical classification systems and can be applied to all PPFx regardless of the bone or joint involved. The treatment of PPFx requires individual therapeutic concepts taking patient-dependent and patient-independent factors into consideration. The conservative treatment of PPFx is only justified in exceptional situations. In contrast, the choice between operative treatment and deciding between osteosynthesis or revision arthroplasty is particularly based on the assessment of the implant stability. In order to achieve fracture consolidation and also a good functional outcome, knowledge of the basic biomechanical principles of operative (osteosynthesis or endoprosthesis) treatment of periprosthetic fractures is necessary.

Biomechanical analysis of four augmented fixations of plate osteosynthesis for comminuted mid-shaft clavicle fracture: A finite element approach

Sufficient stabilization of comminuted mid-shaft clavicle fractures via plate fixation is difficult to achieve. Various augmentations, including interfragmentary screws and cerclage wiring, have been adopted to reinforce fixation stability. The present study aimed to assess the biomechanical stability of augmented plate fixations using the finite element method. First, a clavicle fracture model was created from CT data. Fixation was then induced using a locking compressive plate (LCP) with the following four augmentations: i) Double inner cerclage wirings (DICW), ii) double outer cerclage wirings (DOCW), iii) a single interfragmentary screw (SIS) and iv) double interfragmentary screws (DIS). Compressive and bending forces of 100 N were subsequently applied at the acromial region of the clavicle. The stress distribution, displacement and fracture micro-motions of the model were assessed and compared. The DOCW resulted in the highest stress exerted on the LCP, followed by SIS, DICW and DIS. For the clavicle fracture, DICW, DOCW and SIS resulted in high stress levels. However, DIS fixation alone resulted in levels of stress that were below the yield strength of cortical bone. Displacement analysis revealed that DOCW fixation resulted in the greatest degree of displacement and fracture micro-motions, followed by SIS, DICW and DIS. The results indicated that SIS, DIS and DOCW may be used as augmentations of LCP fixation for comminuted mid-shaft clavicle fractures. However, DIS was the recommended augmentation due to it exerting the lowest stress and the highest stability compared with the other fixations. The DICW may be used to aid fracture reduction and plate placement in surgery but should be avoided for permanent fixation.

[Periprosthetic fractures around the knee]

BACKGROUND

Periprosthetic fractures of the knee joint are complex injuries and frequently represent a challenge for the surgeon.

OBJECTIVE

The aim of this review is to present and discuss the current classification and treatment options for periprosthetic knee fractures.

MATERIAL AND METHODS

A selective review of the existing literature on periprosthetic fractures around the knee was performed in PubMed. The various classifications and treatment regimens are discussed with respect to the advantages and disadvantages and from this knowledge a new algorithm was developed.

RESULTS

The classifications of periprosthetic fractures have changed in recent years and have been replaced by a uniform fracture classification; however, not only the radiological evaluation of the fractures is crucial to determine the treatment regimen for periprosthetic fractures. A thorough evaluation of the inserted endoprosthesis should be carried out in order to be able to decide between the treatment options of osteosynthesis and revision arthroplasty. Treatment options are available for osteosynthesis and revision arthroplasty that enable a safe treatment of these complex injuries.

CONCLUSION

Periprosthetic fractures of the knee joint are complex injuries, requiring a thorough preoperative planning and an interdisciplinary treatment with trauma and endoprosthetic expertise.

Effectiveness of circular external fixator in periprosthetic fractures around the knee

Background

The incidence of periprosthetic fractures after total joint arthroplasty (TJA) is rising due to an increasing number of TJAs performed annually and the growing elderly population. In many elderly patients with periprosthetic fractures, the bone strength is lowered due to the deterioration of bone quality and a decrease in bone quantity; rigid fixation of the fracture is difficult. It is a challenging operation for orthopedic surgeons. The usefulness of circular external fixation for periprosthetic fractures has been reported in several case studies. The aim of this study was to investigate the rate of union and complications associated with circular external fixation in periprosthetic fractures around the knee.

Methods

We included 19 patients with periprosthetic femur and tibial fractures who underwent osteosynthesis using a circular external fixator and had at least 2 years of follow-up. All patients had comorbidities and high risks associated with anesthesia. Tourniquets were not used in any of the patients. There were no cases in which the skin incision was placed, and the closed reduction technique was used in all cases.

Results

A 100% union rate was achieved with no serious complications. All fractures healed after a mean time of 14.3 ± 5.2 weeks (range, 8–38 weeks). The walking ability was the same level as before the injury in 13 cases.

Discussion

There are many comorbidities associated with periprosthetic fractures in elderly patients. Double-plate or revision surgery were largely invasive and had high risks associated with anesthesia. Circular external fixation is a feasible and effective treatment option because it provides stable fixation, prompt postoperative mobilization, and has no major complications, especially in elderly patients who are treated for periprosthetic fractures.

Conclusion

Circular external fixation is a safe and reliable method for periprosthetic fractures around the knee in elderly patients.

Level of evidence

Level IV, retrospective case series.

Biomechanics of Osteoporotic Fracture Fixation

PURPOSE OF REVIEW

Fractures of osteoporotic bone in elderly individuals need special attention. This manuscript reviews the current strategies to provide sufficient fracture fixation stability with a particular focus on fractures that frequently occur in elderly individuals with osteoporosis and require full load-bearing capacity, i.e., pelvis, hip, ankle, and peri-implant fractures.

RECENT FINDINGS

Elderly individuals benefit immensely from immediate mobilization after fracture and thus require stable fracture fixation that allows immediate post-operative weight-bearing. However, osteoporotic bone has decreased holding capacity for metallic implants and is thus associated with a considerable fracture fixation failure rate both short term and long term. Modern implant technologies with dedicated modifications provide sufficient mechanical stability to allow immediate weight-bearing for elderly individuals. Depending on fracture location and fracture severity, various options are available to reinforce or augment standard fracture fixation systems. Correct application of the basic principles of fracture fixation and the use of modern implant technologies enables mechanically stable fracture fixation that allows early weight-bearing and results in timely fracture healing even in patients with osteoporosis.

Secondary femur shaft fracture following treatment with cephalomedullary nail: a retrospective single-center experience

AIM

Secondary femur fracture subsequent to treatment of trochanteric fractures with cephalomedullary nailing (i.e., a periprosthetic fracture related to the cephalomedullary nail) is a rare but very severe complication. As such, the aim of this study was to assess the impact of revision surgery and general state of health on mortality and functional outcomes in patients suffering femur fractures following treatment with cephalomedullary nails.

MATERIALS AND METHODS

Between 2000 and 2015, 3549 patients presenting with OTA/AO 31A1-3 femur fractures were admitted to our department and subsequently treated with either a Gamma^® Nail or PFNA^®. Out of this sample population, 42 patients suffered 43 secondary femur shaft fractures (1.2%). The mean follow-up time was 26 ± 9.7 months. Fractures were classified according to the AO classification and the modified Vancouver classification. Treatment options included ORIF, removing the cephalomedullary nail and fixation with a long nail with or without cerclage wires. General health status was defined according to the ASA Score. Mortality, pre- and postoperative mobility, hospital stay and complications were assessed retrospectively.

RESULTS

A total of 14.3% patients died within 90 days following surgery. At least 16.6% patients died due to medical complications strongly related to the surgery. The average time to secondary fracture following initial surgery for trochanteric fracture was 122.7 ± 32 weeks. The most common fracture types were AO 32A1 (53.5%) and AO 32B1 (23.3), as well as Vancouver C and B1. A time-to-secondary-fracture of less than or longer than 6 months following surgery for trochanteric fracture and ASA Score all had no significant influence on mortality, complications, duration of surgery and postoperative mobility.

CONCLUSION

Femoral shaft facture subsequent to fixation of trochanteric fracture with cephalomedullary nails is a severe complication. It leads to prolonged hospital stays and delayed recovery. Postoperative hospital stay mortality rates may be as high as 16.6%.