Periprosthetic femoral fracture--a biomechanical comparison between Vancouver type B1 and B2 fixation methods

Subsidence in Centraliser Sign: A Novel Tool to Help Predict Early Subsidence in Periprosthetic Femoral Fractures Around Polished Tapered Stems Treated With Internal Fixation

Background When treating periprosthetic femoral fractures (PPF) around polished taper slip stems (PTS), determining which patients can be successfully treated with internal fixation can be challenging. We have described the subsidence-in-centraliser (SINC) sign as a radiographic feature of PPF around PTS stems. We hypothesise that a positive SINC sign can help predict a poorer outcome for the fixation of these fractures. Patients and methods Retrospective identification of PPFs around cemented PTS with an appreciable centraliser on radiographs was conducted at a single centre. A positive SINC sign was defined as a post-injury radiograph demonstrating >50% reduction in the radiographic lucency representing the stem centraliser when compared to pre-injury films or complete obliteration of distal lucency when no pre-injury film was available. The primary outcome was the rate of subsequent stem subsidence on follow-up radiographs comparing SINC-positive and SINC-negative fractures, which were managed with open reduction and internal fixation (ORIF). Results Fifty-four patients were included in the analysis. The mean age was 76.8 years, and the mean follow-up for all patients was 12.7 months. Thirty-five fractures were deemed SINC-positive, and 19 were SINC-negative. 17/17 (100%) SINC-positive fractures managed with fixation underwent further subsidence (mean 5.4 mm, SD 2.8). A positive SINC sign demonstrated a sensitivity of 90.5% and specificity of 100% for subsequent stem subsidence in fractures treated without revision. SINC positive fractures underwent significantly more subsidence compared with SINC negative fractures when fixed (5.4 mm vs. 0.28 mm, U = 6.50, p<0.001) at a mean follow-up of 12.7 months. The SINC sign demonstrated strong inter- (k=0.96) and intra-rater (k=0.86) reliability. Conclusion The SINC sign can serve as a useful adjunct in the decision to fix or revise PPF around PTS. A positive SINC sign may represent a cement mantle that cannot be reconstituted anatomically, leading to subsidence after treatment with ORIF.

The Stability of Fixation of Vancouver B2 Periprosthetic Femoral Fractures: Effect of Implantation Technique

INTRODUCTION

Due to increasing volume of total hip arthroplasties, periprosthetic femoral fractures have become a common complication with increased revision burden and perioperative morbidity. The objective of this study was to evaluate the fixation stability of Vancouver B2 fractures treated with two techniques.

METHODS

A common B2 fracture was created by reviewing 30 type B2 cases. The fracture was then reproduced in 7 pairs of cadaveric femora. The specimens were divided into two groups. In Group I ("reduce-first"), the fragments were reduced first, followed by implantation of a tapered fluted stem. In Group II ("ream-first"), the stem was implanted in the distal femur first, followed by fragment reduction and fixation. Each specimen was loaded in a multi-axial testing frame with 70% of peak load during walking. A motion analysis system was used to track the motion of the stem and fragments.

RESULTS

The average stem diameter in Group II was 16.1±0.4 millimeters (mm), versus 15.4 ±0.5mm in Group I. The fixation stability was not significantly different in the two groups. After the testing, the average stem subsidence was 0.36±0.31mm and 0.19±0.14mm (P=0.17), and the average rotation was 1.67±1.30° and 0.91±1.11° (P=0.16) in Group I and II, respectively. Compared to the stem, there was less motion of the fragments, and there was no difference between the two groups (P>0.05).

CONCLUSIONS

When tapered fluted stems were used in combination with cerclage cables for treatment of type B2 periprosthetic femoral fractures, both the "reduce-first" and "ream-first" technique showed adequate stem and fracture stability.

Mini-invasive approach vs. traditional open reduction for periprosthetic hip fracture osteosynthesis with the NCB® plate

BACKGROUND

Postoperative hip periprosthetic fracture (PPF) is a frequent complication whose treatment does not achieve optimal results among eldery fragile patients. Locking compression plate (LCP) osteosynthesis is the gold standard treatment for Vancouver B1 and VC fractures and there is a growing consensus in doing the same with B2 fractures in patients with high comorbidity. Following that trend of being as non-aggressive as possible we investigated whether a mini-open (MO) approach would lead to better outcomes in LCP plate osteosynthesis of hip PFFs when compared to the traditional open approach.

METHODS

We retrospectively evaluated a cohort of 43 VB1, VB2 or VC hip PPFs treated with non contact bridging (NCB®) plate osteosynthesis by two possible approaches. MO vs traditional open approach. The main objective was to assess whether MO approach decreases operative time, bleeding and local complications. The secondary objective was to demonstrate that this may have a positive effect on patient function.

RESULTS

The mean age was 79.6 years old and 74.5% patients had an ASA score of III or IV. The surgical time was 148.53 min (SD 33.2) in the open approach versus 107.42 min (SD 25.6) in the MO, which was 31 min shorter (p<0.001). Hemoglobin dropped 0.9 points less, on average (p. 0.005) and 0.82 fewer blood concentrates were required (p. 0.022) with MO approach. There were no differences among complications but there was a trend towards greater independence and better mobility in the MO approach group with a postoperative Barthel of 74.37 (sd. 13.21) compared to the 66.67 points (sd. 13.7) in the traditional approach group.

CONCLUSION

MO approach in osteosynthesis of hip PFFs decreases operative time and intraoperative bleeding so it must be considered in fragile patients with high comorbidity.

Mortality and clinical outcomes of Vancouver type B periprosthetic femoral fractures : a multicentre retrospective study

AIMS

The objectives of this study were to investigate the patient characteristics and mortality of Vancouver type B periprosthetic femoral fractures (PFF) subgroups divided into two groups according to femoral component stability and to compare postoperative clinical outcomes according to treatment in Vancouver type B2 and B3 fractures.

METHODS

A total of 126 Vancouver type B fractures were analyzed from 2010 to 2019 in 11 associated centres' database (named TRON). We divided the patients into two Vancouver type B subtypes according to implant stability. Patient demographics and functional scores were assessed in the Vancouver type B subtypes. We estimated the mortality according to various patient characteristics and clinical outcomes between the open reduction internal fixation (ORIF) and revision arthroplasty (revision) groups in patients with unstable subtype.

RESULTS

The one-year mortality rate of the stable and unstable subtype of Vancouver type B was 9.4% and 16.4%. Patient demographic factors, including residential status and pre-injury mobility were associated with mortality. There was no significant difference in mortality between patients treated with ORIF and Revision in either Vancouver B subtype. Patients treated with revision had significantly higher Parker Mobility Score (PMS) values (5.48 vs 3.43; p = 0.00461) and a significantly lower visual analogue scale (VAS) values (1.06 vs 1.94; p = 0.0399) for pain than ORIF in the unstable subtype.

CONCLUSION

Among patients with Vancouver type B fractures, frail patients, such as those with worse scores for residential status and pre-injury mobility, had a high mortality rate. There was no significant difference in mortality between patients treated with ORIF and those treated with revision. However, in the unstable subtype, the PMS and VAS values at the final follow-up examination were significantly better in patients who received revision. Based on postoperative activities of daily life, we therefore recommend evision in instances when either treatment option is feasible.Cite this article: Bone Jt Open 2023;4(1):38-46.

Treatment algorithm in Vancouver B2 periprosthetic hip fractures: osteosynthesis vs revision arthroplasty

There is currently a debate on whether all Vancouver B2 periprosthetic hip fractures should be revised.

The aim of our work was to establish a decision-making algorithm that helps to decide whether open reduction and internal fixation (ORIF) or revision arthroplasty (RA) should be performed in these patients.

Relative indications in favour of ORIF are low-medium functional demand (Parker mobility score (PMS) <5), high anaesthetic risk (American Society of Anesthesiologists score (ASA) ≥ 3), many comorbidities (Charlson Comorbidity Index (CCI) ≥ 5), 1 zone fractured (VB2.1), anatomical reconstruction possible, and no prior loosening (hip pain).

Relative indications in favour of RA are high functional demand (PMS ≥6), low anaesthetic risk (ASA< 3), few comorbidities (CCI<5), fracture ≥ 2 zones (VB2.2), comminuted fractures, and prior loosening (hip pain).

In cemented stems, those fractures with fully intact cement–bone interface, no stem subsidence into the cementraliser, cement mantle anatomically reducible, and some partial stem-cement attachment can be safely treated with ORIF.

Metal and composite bone plates for B1 periprosthetic femoral fracture in healthy and osteoporotic condition: A comparative biomechanical study

The major concern after total hip arthroplasty (THA) is the incidence of periprosthetic fracture in the weaker bone, which can lead to subsequent revision surgery. Achieving the suitable fixation without affecting the stability of the well-fixed prosthesis remains controversial. Most of the studies examined the behavior of the Periprosthetic Fracture (PF) fixation (Vancouver “B1” type) through computational and experimentation on healthy bone condition with metal plates. The aim of the present study is to analyze the influences of the metal and composite bone plate PF fixation on the axial and shear movement at the fracture site. The PF fixation constructs were modeled with medical graded stainless-steel plate (construct A), titanium plate (construct B) and carbon/epoxy composite bone plate (construct C) with 12 holes and a 4 mm fracture gap. Analysis was carried out for all the stages (stage 1—Normal bone, stage 2—THA, stage 3—Immediate Post-Operative (IPO), stage 4—Post-Operative (PO) and, stage 5—Healed Bone (HB)) under various loadings for intact and osteoporosis conditions. The results showed higher stress in cortical bone for stage 3, whereas in all the other stages lower stresses were experienced in the cortical and cancelous bone under peak load in construct C for osteoporosis model compared with other constructs. The present study suggested the construct C may be suitable for osteoporosis bone conditions.

Simplified Mechanical Tests Can Simulate Physiological Mechanics of a Fixation Construct for Periprosthetic Femoral Fractures

Plate fractures after fixation of a Vancouver Type B1 periprosthetic femoral fracture (PFF) are difficult to treat and could lead to severe disability. However, due to the lack of direct measurement of in vivo performance of the PFF fixation construct, it is unknown whether current standard mechanical tests or previous experimental and computational studies have appropriately reproduced the in vivo mechanics of the plate. To provide a basis for the evaluation and development of appropriate mechanical tests for assessment of plate fracture risk, this study applied loads of common activities of daily living (ADLs) to implanted femur finite element (FE) models with PFF fixation constructs with an existing or a healed PFF. Based on FE simulated plate mechanics, the standard four-point-bend test adequately matched the stress state and the resultant bending moment in the plate as compared with femur models with an existing PFF. In addition, the newly developed constrained three-point-bend tests were able to reproduce plate stresses in models with a healed PFF. Furthermore, a combined bending and compression cadaveric test was appropriate for risk assessment including both plate fracture and screw loosening after the complete healing of PFF. The result of this study provides the means for combined experimental and computational preclinical evaluation of PFF fixation constructs.

New Sub-Classification of Vancouver B2 Periprosthetic Hip Fractures According to Fracture Pattern

INTRODUCTION

There is currently a debate on whether all Vancouver type B2 (V-B2) periprosthetic hip fractures (PPHF) should be revised. Vancouver classification takes into account fracture location, implant stability and bone stock, but it does not distinguish between fracture patterns. The aim of our work was to study the different fracture patterns of V-B2 PPHF and to analyze if there is any pattern that presents lower osteosynthesis failure rates.

MATERIAL AND METHODS

All patients with V-B2 PPHF treated by osteosynthesis between January 2009 and January 2019 were included in the study. Using the Gruen system the proximal femur was divided into 3 zones. The lateral zone (Gruen 1±2±3), medial zone (Gruen 5±6±7), and distal zone (Gruen 4±3±5) were analysed and it was determined whether each of the 3 zones was fractured.

RESULTS

56 patients were included in the study. Their mean age was 79 years (R 45 - 92). The chosen treatment was: 39 Open reduction and internal fixation (ORIF), 10 Stem revision and 7 nonoperatively treatment. In ORIF group, no implant complications (0/24) were found in patients with a single fractured zone, while 5 implant complications (5/15) were discovered in patients with two or more fractured areas; this difference was significant (p=0.0147). All patients treated by stem revision had a fracture that involved two or more zones. In the nonoperatively group, the fracture pattern did not influence the treatment because of all of them had a very precarious functional and medical situation.

CONCLUSIONS

V-B2 PPHF treated via ORIF affecting only one zone (medial, lateral, or distal) have a lower risk of complication than those affecting two or more zones. We propose a sub-classification of Vancouver B2 type fractures: B2.1 (1 fractured zone) and B2.2 (≥2 fractured zones).

LEVEL OF EVIDENCE

Historical cohorts. Level III.

Differences between two sequential uncemented stem sizes in total hip arthroplasty: A comparative biomechanical study and potential clinical implications

Background: Early failure of uncemented femoral stems associated with incorrect sizing is a known postoperative complication. Surgeons are often faced with the question of whether an uncemented stem of adequate stability or a larger-sized stem should be implanted, especially when the proximal femoral cancellous bone is adequate. The biomechanical effect of sub-optimal stem sizing in the femur remains unclear. This study investigated the mechanical behaviour of two sequential sized uncemented stems of the same type. Methods: Six laboratory models of synthetic non-osteoporotic femora were randomly divided into two groups and implanted with either a nominal or oversized uncemented hydroxyapatite-coated nonporous titanium collarless stem. Stiffness, uniaxial strain, and pattern of strain distribution were measured under an anatomical one-legged stance. Results: Oversized stems demonstrated a higher overall stiffness compared to nominal; however, this was not statistically significant. The nominal stem showed a higher strain in the neck and the proximal medial diaphyseal region. The oversized stem showed higher strains in the distal region around the implant tip. Conclusion: Opting to use a larger stem may potentially increase primary stability, thus allowing safer early mobility. However, higher stiffness may lead to stress shielding, bone loss, and thigh pain in the long term. In addition, strains in the diaphysis and the tip of the stem may predispose to periprosthetic fractures, especially in osteoporotic bones, making this a relatable aspect for users and biomechanical loading. Given the wide range of complex factors that need to be considered when choosing stem size in uncemented THA surgery, this study’s results should be interpreted cautiously.

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.

Impact of periprosthetic femoral fracture fixation plating constructs on local stiffness, load transfer, and bone strains

Secondary femoral fractures after the successful plate-screw fixation of a primary Vancouver type B1 periprosthetic femoral fracture (PFF) have been associated with the altered state of stress/strain in the femur as the result of plating. The laterally implanted condyle-spanning plate-screw constructs have shown promises clinically in avoiding secondary bone and implant failures as compared with shorter diaphyseal plates. Though the condyle-spanning plating has been hypothesized to avoid stress concentration in the femoral diaphysis through increasing the working length of the plate, biomechanical evidence is lacking on how plate length may impact the stress/strain state of the implanted femur. Through developing and experimentally validating finite element (FE) models of 3 cadaveric femurs, this study investigated the impact of plating on bone strains, load transfer and local stiffness, which were compared between FE models of 2 different plating systems that each had a diaphyseal configuration and a condyle-spanning configuration. Under simulated gait-loading, the condyle-spanning constructs of both plating systems were shown to lower the bone strains around the distal fixation screws (up to 24.8% reduction in maximum principal strain and 26.6% reduction in minimum principal strain) and in the distal metaphyseal shaft of the femur (up to 15.9% and 25.7% reductions in maximum and minimum principal strains, respectively), where secondary bone fractures have been typically reported. In the distal diaphyseal and metaphyseal shaft of femur, FE models of the condyle-spanning constructs were shown to increase the local compressive stiffness (up to 152.9% increases under simulated gait-loading) and decrease the transfer of compressive load (37.1% decreases under simulated gait-loading), which may be indicative of the lowered risks of bone damage.

Morphological Measurement of the Femoral Anterior Bow in Chinese Population Based on Three-Dimensional Computed Tomography

Purpose

The femoral anterior bow is an important factor in matching a femoral implant to a femur. However, its morphology in the Chinese population has rarely been reported. In this study, a three-dimensional measurement approach was adopted to provide accurate data. The aim was to supply a reference for designing a long-stemmed femoral prosthesis that is more suitable for Chinese people.

Methods

Computed tomography data were collected from both lower limbs of 96 normal volunteers and reconstructed into a three-dimensional model using Mimics software. The parameters of the femoral anterior bow were measured using medical image analysis software. Statistical analysis was conducted using independent-samples and paired-samples t-tests with SPSS software.

Results

All the indexes showed significant sexual difference (P < 0.05). The minimum cross-sectional area of the femoral medullary cavity was larger in men (10.77 ± 1.53 mm) than in women (9.79 ± 1.27 mm). The distance from the position of the maximum curvature to the lower edge of the lesser trochanter was also larger in men (60.93 ± 5.81 mm) than in women (56.31 ± 2.80 mm). However, the curvature of the femoral medullary cavity centerline was larger in women (883.57 ± 249.74 mm) than in men (958.79 ± 266.61 mm). The femoral anterior bow morphological indexes of Chinese subjects were different from the published data for other populations. There were no significant differences between left and right femoral anterior bows in either sex (P > 0.05).

Conclusion

The three-dimensional measurement approach adopted in this study is more convenient and accurate than previous conventional methods, with high repeatability. The morphological indexes of the femoral anterior bow in this research suggest that population characteristics should be taken into account. This study will provide references for the design of long-stemmed femoral prostheses in the Chinese population.

Periprosthetic Hip Fractures With a Loose Stem: Open Reduction and Internal Fixation Versus Stem Revision

BACKGROUND

It is recommended revision for periprosthetic hip fractures (PPHF) with a loose stem. However, several authors have argued that under certain conditions, this fracture could be treated using osteosynthesis. The aim is to compare stem revision versus internal fixation in the treatment of PPHF with a loose stem.

METHODS

All patients with PPHF with a loose stem treated by osteosynthesis and stem revision between January 2009 and January 2019 were included. We assessed hospital stay, American Society of Anesthesiologists, Charlson comorbidity index, surgery time, blood transfusion, complications, reoperation rate, first-year mortality, radiological, and functional results.

RESULTS

A total of 57 patients were included (40 osteosyntheses and 17 stem revision), with an average follow-up time of 3.1 years. Their mean age was 78.47 years (R 45-92). In the osteosynthesis group, fewer patients required blood transfusion (32.5% vs. 70.6%), surgical times were shorter (108 minutes vs. 169 minutes), and the cost was lower, both in terms of total cost (€14,239.07 vs. €21,498.45 and operating room cost (€5014.63 vs. €8203.34). No significant differences were found between the groups in terms of complications, reoperation rate, or functional outcomes.

CONCLUSION

Compared with stem revision, osteosynthesis requires less surgery time, has a lower need for blood transfusions, and a reduced hospital cost. Stem revision remains the treatment of choice in PPHF with a loose stem, but in V-B2 fractures in elderly patients with low functional demand, high anesthetic risk (American Society of Anesthesiologists ≥3), and many comorbidities (Charlson comorbidity index ≥5) in whom anatomic reconstruction is possible, osteosynthesis can be a viable option.

EVIDENCE LEVEL

Historical cohorts. Level III.

Multiple failures of internal fixation for treatment of periprosthetic femoral refracture: a case report and literature review

We herein report a case involving three failures of internal fixation after periprosthetic femoral fracture (Vancouver type B1). The patient had low bone mass (T-score of −1.7) and was overweight (body mass index of 28.7 kg/m²) but had no sign of femoral stem loosening. The first open reduction with internal fixation was performed according to the recommended treatment. Unexpectedly, three treatment failures subsequently occurred, after which the patient finally attained endurable walking activity. A literature review indicated that the intrinsic biomechanical problems of Vancouver B1 fractures have not been thoroughly addressed. Choosing the correct surgical strategy for Vancouver B1 fractures is essential to avoid complications and ensure healing. A sufficient locking plate and cable system should be used after the first failure if revision was not performed the first time.

Biomechanics of periprosthetic femur fractures and early weightbearing

PURPOSE

The incidence of periprosthetic fractures is expected to rise increase by 4.6% every 10 years between 2015 and 2060. There are few large series examining optimal fixation constructs or the influence of early ambulation on outcome. The purpose of this narrative review is to investigate the published biomechanical considerations for periprosthetic fracture fixation, with specific consideration of early postoperative weightbearing.

METHODS

A literature review was performed to identify fracture incidences, etiology, and current trends in weightbearing after fixation. Benefits of early weightbearing, current constructs, and biomechanics are reviewed.

RESULTS

The limited data available support medical benefits and increased union rates with early mobilization. Optimal fixation constructs are not agreed upon, but mechanical studies suggest that dual implant constructs can support physiologic weightbearing loads.

CONCLUSION

Further clinical trials are required to investigate fracture union and hardware complications in dual implant construct.

Finite element analysis of double-plate fixation using reversed locking compression-distal femoral plates for Vancouver B1 periprosthetic femoral fractures

Background

Internal fixation is recommended for treating Vancouver B1 periprosthetic femoral fractures. Although several fixation procedures have been developed with high fixation stability and union rates, long-term weight-bearing constructs are still lacking. Therefore, the aim of the present study was to evaluate the stability of a double-plate procedure using reversed contralateral locking compression-distal femoral plates for fixation of Vancouver B1 periprosthetic femoral fractures under full weight-bearing.

Methods

Single- and double-plate fixation procedures for locking compression-distal femoral plates were analysed under an axial load of 1,500 N by finite element analysis and biomechanical loading tests. A vertical loading test was performed to the prosthetic head, and the displacements and strains were calculated based on load-displacement and load-strain curves generated by the static compression tests.

Results

The finite element analysis revealed that double-plate fixation significantly reduced stress concentration at the lateral plate place on the fracture site. Under full weight-bearing, the maximum von Mises stress in the lateral plate was 268 MPa. On the other hand, the maximum stress in the single-plating method occurred at the defect level of the femur with a maximum stress value of 1,303 MPa. The principal strains of single- and double-plate fixation were 0.63 % and 0.058 %, respectively. Consistently, in the axial loading test, the strain values at a 1,500 N loading of the single- and double-plate fixation methods were 1,274.60 ± 11.53 and 317.33 ± 8.03 (× 10^− 6), respectively.

Conclusions

The present study suggests that dual-plate fixation with reversed locking compression-distal femoral plates may be an excellent treatment procedure for patients with Vancouver B1 fractures, allowing for full weight-bearing in the early postoperative period.

Results after surgical treatment of periprosthetic proximal femoral fractures. Osteosynthesis with prosthesis preservation vs. prosthesis change

Background: Periprosthetic fractures (PPF) of the femur close to the hip joint have serious consequences for most geriatric affected patients. In principle, apart from the highly uncommon conservative therapy, there are two therapeutic options. On the one hand, the prosthesis-preserving treatment by means of osteosynthesis using plates and/or cerclages in general is available. On the other hand, a (partial) change of the prosthesis with optionally additive osteosynthesis or a proximal femoral replacement can be performed because of prosthesis loosening or non-reconstructable comminuted fractures as well as most cemented stem variations.

The aim of this retrospective study is the analysis of periprosthetic proximal femoral fractures in the presence of a total hip arthroplasty (THA). The outcome of the operated patients is to be investigated depending on the type of care (osteosynthesis with prosthesis preservation vs. prosthesis change).

Material and methods: In a retrospective case analysis, 80 patients with THA and PPF were included. They were divided into two groups. Group I represents the osteosynthetic treatment to preserve the implanted THA (n=42). Group II (n=38) includes those patients who were treated by a change of their endoprosthesis with or without additional osteosynthesis. Specifics of all patients, like gender, age at fracture, interval between fracture and implantation, length of in-patient stay, body mass index, osteoporosis, corticomedullary index and complications such as infections, re-fracture, loosening, material failure or other complications, were recorded and compared. Furthermore, the patients were re-examined by a questionnaire and the score according to Merle d’Aubigné and Postel.

Results: In group I the mean follow-up time was 48.5±23 months (4 years) whereas group II amounted 32.5±24.5 months (2.7 years) (p=0.029). Besides, there were significant differences in age (81± 11 years vs. 76±10 years, p=0.047) and length of in-patient stay (14.5±8.6 days vs. 18.0±16.7 days, p=0.014). According to the score of Merle d’Aubigné and Postel, there were significantly better values for the pain in group II with comparable values for mobility and walking ability.

Conclusion: The treatment of periprosthetic proximal fractures of the femur is dependent on the classification (Vancouver and Johannsen) and in particular on the prosthetic anchoring as well as the extent of the comminution zone. Older patients and patients with osteoporosis are more frequently treated with an endoprosthesis revision. Patients, who have been treated with an osteosynthesis for preserving their endoprosthesis, showed a shorter length of in-patient stay and fewer complications than people with replacement surgery. In contrast to that, patients with prosthesis revision had better outcomes concerning the score of Merle d’Aubigné and Postel.

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.

A biomechanical study on the laminate stacking sequence in composite bone plates for vancouver femur B1 fracture fixation

BACKGROUND AND OBJECTIVES

Composite bone plates are proposed for fracture fixation in periprosthetic femoral fracture. Metallic plates, having high stiffness compared to bone lead to stress shielding, reduce the compression force in the fracture site, affectthe healing process. Reduction of stiffness in the axial direction due to above reason without lowering the stiffness in transverse to avoid much of shear strain and thus avoiding instability at the fracture site leads to selective stress shielding. This can only be achieved through meticulously designed fiber reinforced composite. In the present work varied fiber orientations in the stacked laminates with varied fiber types are employed in a post-operative femur fixation for the in-silico analyses of their effectiveness using finite element analysis.

METHODS

In this study a Total Hip Arthroplasty (THA) model is constructed with composite bone plates. Three-dimensional narrow type metal plate is modeled with 12 holes and length of 194 mm. Three different types of composite bone plates are modeled with 12 holes of different size for the analysis i.e. Type 1 (5.6 mm thickness and 16 mm width), Type 2 (6 mm thickness and 16 mm width) and Type 3(6 mm thickness and 18 mm width). Anatomical 3D FE models of THA with composite bone plates are constructed to find out the interfacial stresses and strains. The finite element software ANSYS is used to perform the analysis.

RESULTS

A three-dimensional FE model of immediately post-operative femur fixation is developed and studied the maximum stress distribution, strain and movement in axial/shear direction in the metal and composite bone plate near to the fracture site. In the present study, the metal and composite plate (carbon/epoxy, glass/epoxy and flax/epoxy) used for most common Vancouver type B1 fracture to observe the biomechanical behavior of different models in IPO condition using FEA.

CONCLUSIONS

Optimizing the fiber orientations of composite bone plates of Total Hip Arthroplasty (THA) model by controlling the biomechanical stresses could be a favorable approach. The finite element analysis approach gives a viable solution to design the composite bone plate and for designing future models that preserves the biomechanical function of THA with composite bone plate.

Treatment and outcomes of Vancouver type B periprosthetic femoral fractures

Aims

Vancouver type B periprosthetic femoral fractures (PFF) are challenging complications after total hip arthroplasty (THA), and some treatment controversies remain. The objectives of this study were: to evaluate the short-to-mid-term clinical outcomes after treatment of Vancouver type B PFF and to compare postoperative outcome in subgroups according to classifications and treatments; to report the clinical outcomes after conservative treatment; and to identify risk factors for postoperative complications in Vancouver type B PFF.

Methods

A total of 97 consecutive PPFs (49 males and 48 females) were included with a mean age of 66 years (standard deviation (SD) 14.9). Of these, 86 patients were treated with surgery and 11 were treated conservatively. All living patients had a minimum two-year follow-up. Patient demographics details, fracture healing, functional scores, and complications were assessed. Clinical outcomes between internal fixation and revisions in patients with or without a stable femoral component were compared. Conservatively treated PPFs were evaluated in terms of mortality and healing status. A logistic regression analysis was performed to identify risk factors for complications.

Results

In surgically treated patients, all fractures united and nine complications were identified. The mean postoperative Visual Analogue Scale (VAS) for pain was 1.5 (SD 1.3), mean Parker Mobility Score (PMS) was 6.5 (SD 2.4), and mean Harris Hip Score (HHS) was 79.4 (SD 16.2). Among type B2 and type B3 fractures, patients treated with internal fixation had significantly lower PMS (p = 0.032) and required a longer time to heal (p = 0.012). In conservatively treated patients, one-year mortality rate was 36.4% (4/11), and two patients ultimately progressed to surgery. Young age (p = 0.039) was found to be the only risk factor for complications.

Conclusion

The overall clinical outcome among Vancouver type B PFF was satisfactory. However, treatment with internal fixation in type B2 and B3 fractures had a significantly longer time to heal and lower mobility than revision cases. Conservative treatment was associated with high rates of early mortality and, in survivors, nonunion. This probably reflects our selection bias in undertaking surgical intervention. In our whole cohort, younger patient age was a risk factor for postoperative complications in Vancouver type B PFF. Cite this article: Bone Joint J 2020;102-B(3):293–300

Cable plate fixation for Vancouver Type-B1 periprosthetic femoral fractures-Our experience and identification of a subset at risk of non-union

INTRODUCTION

Management of periprosthetic femoral fractures is challenging. Vancouver classification is universally accepted for fracture description and management algorithm. Guidelines for the treatment of type B1 fracture is open reduction and internal fixation. The difficulty involved in managing this group is evidenced by the array of treatment options described in the literature.

METHODS

Thirty two patients with Vancouver type B1 fracture treated with osteosynthesis using cable plate (between 2007 and 2015) were reviewed retrospectively. There were 21 females and 11 males with an average age of 81yrs (56-96 years). The average follow-up was 21 months. All patients were reviewed clinically and radiologically until fracture united or patient re-operated. Postoperative protocol followed was six weeks toe touch weight bearing, 6 weeks partial weight bearing and then full weight bearing if there was no displacement. Post-operative radiographs were evaluated for fracture union. Statistical analysis was done using contingency tables with Fishers exact test and a p-value < 0.05 for significance.

RESULTS

In twenty four patients fracture union was achieved. Non-union was recorded in four patients. Comparing the different fracture patterns all non-unions occurred in the fractures which were short oblique or transverse at the cemented stem tip (p = 0.001). Fractures were more common in female patients and associated more with the uncemented femoral stems, but it was not associated with increased rate of non-union (p = 0.68). All failed osteosynthesis were revised successfully using long stem prosthesis. Two patients died within 2 months, one patient died within 4 months, one patient was lost to follow-up.

CONCLUSION

Transverse or short oblique periprosthetic fractures around tip of cemented femoral stems can have high failure rates with just internal fixation. Revision arthroplasty may be the preferred option if possible otherwise may need to supplement fixation with cortical onlay graft. We should consider subcategorising Vancouver type B1 periprosthetic fractures into groups based on the pattern and fracture level in relation to the femoral stem.

Reliability and Validity of the Vancouver Classification in Periprosthetic Fractures Around Cementless Femoral Stems

BACKGROUND

The Vancouver classification of periprosthetic femur fractures divides B1 and B2 subtypes based on the stability of the femoral stem. However, this classification was described and validated with cemented femoral stems. We sought to assess reliability and validity of the Vancouver classification in patients with cementless femoral stems.

METHODS

This is a blinded radiographic study which included patients treated for Vancouver B cementless periprosthetic femur fractures between February 2007 and December 2017. Adult reconstruction-trained and trauma fellowship-trained orthopedic surgeons graded all preoperative radiographs using the Vancouver classification on 3 separate occasions. Interobserver and intraobserver reliability was assessed via the Fleiss' kappa statistic. Validity was assessed via accuracy between radiographic and intraoperative assessments. The Landis and Koch criteria were used to interpret the kappa values.

RESULTS

Fifty-three patients with Vancouver B fractures (B1, 8; B2, 45) around a cementless femoral stem were included in the study. Five reconstruction-trained and 5 trauma-trained orthopedic surgeons graded all radiographs. The interobserver reliability kappa value was 0.45 (moderate agreement), with all raters agreeing on only 43% of radiographs. Validity analysis showed demonstrated 79% agreement. Overall, 20% (range, 14%-24%) of unstable B2 fractures were misread as B1 fractures. Intraobserver reliability was 0.71 between readings.

CONCLUSION

The reliability of the Vancouver classification for cementless total hip arthroplasty is lower than previously described in cemented femoral stems. Radiographic assessment alone may be inadequate for determination of stability of cementless stems in periprosthetic femur fractures.

LEVEL OF EVIDENCE

Level III therapeutic study: retrospective comparative study.

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.

Radiologic outcomes of open reduction and internal fixation for cementless stems in Vancouver B2 periprosthetic fractures

Objective

The aim of this study was to evaluate the radiologic outcomes of open reduction and lateral plating with wiring in the treatment of Vancouver B2 periprosthetic femoral fractures.

Methods

We retrospectively recruited 37 patients treated with ORIF with lateral plating and wiring for Vancouver B2 fractures. The 27 patients (15 men and 12 women; mean age: 70.8 ± 8.3 years) without follow-up loss had achieved complete bony union without notable complications. The average union period was checked after operation with radiologic findings. Radiologic outcomes were evaluated by ipsilateral limb length discrepancy (LLD) and subsidence between immediate postoperative length and length at postoperative 1 year after adjusting for magnification differences. The average distance to which the retained stem sunk down was investigated between immediate postoperative radiographs and final radiographs showing union.

Results

Ten patients could not be evaluated, because of mortality or failure to follow up. The average time to union was 18.3 weeks, and the average distance of stem sinking was 2.5 ± 1.7 mm (range: 0–7.2 mm), which was significantly different between immediate postoperative radiographs and final radiographs. There was no case with loss of reduction or loss of fixation, requiring revision surgery.

Conclusion

Open reduction and lateral plating with wiring as a treatment for Vancouver B2 periprosthetic femoral fractures produced good radiologic outcomes with successful bony union. ORIF can be considered the alternative option for treating patients with Vancouver B2 PPF, instead of stem revision surgery.

Level of evidence

Level IV, Therapeutic study.

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 Analysis Using FEA and Experiments of Metal Plate and Bone Strut Repair of a Femur Midshaft Segmental Defect

This investigation assessed the biomechanical performance of the metal plate and bone strut technique for fixing recalcitrant nonunions of femur midshaft segmental defects, which has not been systematically done before. A finite element (FE) model was developed and then validated by experiments with the femur in 15 deg of adduction at a subclinical hip force of 1 kN. Then, FE analysis was done with the femur in 15 deg of adduction at a hip force of 3 kN representing about 4 x body weight for a 75 kg person to examine clinically relevant cases, such as an intact femur plus 8 different combinations of a lateral metal plate of fixed length, a medial bone strut of varying length, and varying numbers and locations of screws to secure the plate and strut around a midshaft defect. Using the traditional “high stiffness” femur-implant construct criterion, the repair technique using both a lateral plate and a medial strut fixed with the maximum possible number of screws would be the most desirable since it had the highest stiffness (1948 N/mm); moreover, this produced a peak femur cortical Von Mises stress (92 MPa) which was below the ultimate tensile strength of cortical bone. Conversely, using the more modern “low stiffness” femur-implant construct criterion, the repair technique using only a lateral plate but no medial strut provided the lowest stiffness (606 N/mm), which could potentially permit more in-line interfragmentary motion (i.e., perpendicular to the fracture gap, but in the direction of the femur shaft long axis) to enhance callus formation for secondary-type fracture healing; however, this also generated a peak femur cortical Von Mises stress (171 MPa) which was above the ultimate tensile strength of cortical bone.

Periprosthetic femoral fractures following total hip and total knee arthroplasty

Total joint arthroplasties are increasing worldwide in both frequency and prevalence. When successful, they offer great improvements in quality of life. However, fractures around implants are often difficult to manage and require prolonged inpatient stays in tertiary hospitals. Management may differ between surgeons, but most patients will be managed surgically if mobility or joint stability is threatened. Those affected are often at higher risk from surgery, are frailer and at higher risk of mortality and a lifelong reduction in mobility. The incidence of these fractures is increasing, and patients should appreciate the risk and implications of this recognised complication of joint arthroplasty.

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.

•

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

•

Reliable transverse fractures were generated and imaged using microCT.

•

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

•

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

•

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

Osteosynthesis of periprosthetic type A and B femoral fractures using an unlocked plate with integrated cerclage cable and trochanteric hook: A multicenter retrospective study of 45 patients with mean follow-up of 20 months

INTRODUCTION

Femoral periprosthetic fracture (FPF) is a frequent complication in dependent elderly persons, with a limited life expectancy. Their management is difficult and the choice between osteosynthesis and prosthesis is still matter of discussion. To date, there is no study on unlocked plate with integrated cerclage cable and trochanteric hook for this indication. The objectives of this study were to analyze fracture healing, complication rate and functional outcome. Our hypothesis is that this technique allows a high rate of consolidation and a return to the previous state in terms of autonomy and place of residence.

MATERIALS AND METHODS

We conducted a retrospective multicenter study between 2010 and 2015. The inclusion criteria were: patients with type A and B FPF according to the classification of Vancouver who received osteosynthesis hook plate. The evaluation focused on the consolidation period, complications and pre and postoperative Parker and Katz scores. Death, nonunion, dislocation, infection and failure of fixation were considered major complications.

RESULTS

Forty-five patients met the inclusion criteria and were evaluated at mean 20 months (6-72). All fractures consolidated at a mean 7 weeks (6-10), except one that has not undergone further surgery in the absence of functional impairment. Parker score decreased from 6.4 to 4.9 (p=0.03) and Katz score from 4.8 to 4.3 (p=0.045). Five patients died within the year of the operation. Five patients living at home preoperatively were admitted to an institution, the others returned to their retirement home or nursing home.

CONCLUSION

This plate allows for a quick and effective management of patients with FPF. The low rate of complications and the very good consolidation rate lead us to use the same plate even for class B2 or B3 fractures in some patients with precarious health condition who cannot tolerate major revision surgery: Elderly, ASA score >3, loss of autonomy, Katz score <4.

Hip revision arthroplasty for failed osteosynthesis in periprosthetic Vancouver type B1 fractures using a cementless, modular, tapered revision stem

Aims

To evaluate the hypothesis that failed osteosynthesis of periprosthetic Vancouver type B1 fractures can be treated successfully with stem revision using a transfemoral approach and a cementless, modular, tapered revision stem with reproducible rates of fracture healing, stability of the revision stem, and clinically good results.

Patients and Methods

A total of 14 patients (11 women, three men) with a mean age of 72.4 years (65 to 90) undergoing revision hip arthroplasty after failed osteosynthesis of periprosthetic fractures of Vancouver type B1 were treated using a transfemoral approach to remove the well-fixed stem before insertion of a modular, fluted titanium stem which obtained distal fixation. These patients were clinically and radiologically followed up for a mean 52.2 months (24 to 144).

Results

After a mean of 15.5 weeks (standard deviation (sd) 5.7) all fractures had healed. No stems subsided and bony-ingrowth fixation had occurred according to the classification of Engh et al. The mean Harris Hip Score increased from a pre-operative score of 22.2 points (sd 9.7) to 81.5 points (sd 16.8) 24 months post-operatively. All hips had obtained an excellent result according to the classification of Beals and Tower.

Conclusions

The technique described here for stem revision provides reproducibly good results in the treatment of failed osteosynthesis for Vancouver types B1 periprosthetic fractures of the hip. Cite this article: Bone Joint J 2017;99-B(4 Supple B):11–16.

Is immediate weight bearing safe for periprosthetic distal femur fractures treated by locked plating? A feasibility study in 52 consecutive patients

Background

Periprosthetic distal femur fractures associated with total knee replacement are increasing in incidence. We hypothesized that a standardized management protocol would result in few implant failures and a low rate of postoperative complications.

Methods

Retrospective observational cohort study at an urban level 1 trauma center and academic level 2 trauma center. Consecutive patients with periprosthetic distal femur fractures and stable total knee arthroplasty were included between January 1, 2011 and December 31, 2014. Patients were managed by a standardized protocol of co-management by a hospitalist service, fracture fixation within 24 h of admission by less-invasive locked bridge plating, and immediate unrestricted postoperative weight bearing. The primary outcome measure was the rate of postoperative complications. Secondary outcome measures included time to surgery, intraoperative blood loss, duration of surgery, length of hospital stay, time to full weight bearing, and time to radiographic fracture healing.

Results

Fifty four fractures were treated in 52 patients. There were three implant failures, one deep infection, one nonunion and two patients with symptomatic malunion. One patient had knee pain due to patellar component instability associated with valgus alignment. There were ten thromboembolic complications despite consistent anticoagulation. Two patients died within 12 months of injury. Thirty-eight patients had returned to their pre-injury ambulation status at 1 year follow-up.

Conclusion

A standardized approach of less-invasive locked plating fixation and immediate unrestricted weight bearing appears safe and feasible in the management of this vulnerable patient cohort.

Trial registration number

This is a retrospective observational study without a Trial registration number.

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.

Managing Vancouver B1 fractures by cerclage system compared to locking plate fixation - a biomechanical study

With increasing life expectancy and number of total hip arthroplasties (THA), the need for revision surgery is increasing too. The aim of this study was to evaluate the optimal fracture treatment for a clinically characteristic Vancouver B1 fracture. We hypothesized that locking plate fixation has biomechanical advantages over fixation with a simple cerclage system. Additionally, we hypothesized that removal of the primary short stem and revision with a long stem would show biomechanical benefit. The biomechanical testing was performed with a static and a dynamic loading protocol on twenty 4th Generation sawbones. These were divided into four different groups (n = 5 each). In group 1, the primary uncemented short stem remained and the fracture was stabilized with a locking plate. In group 2, the primary stem remained and the fracture was stabilized with a cerclage stabilization system containing two stabilizers and four cerclages. In group 3, the primary stem was replaced by an uncemented long revision stem and the fracture was fixed with a locking plate. In group 4, the short stem was replaced by a long revision stem and the fracture was fixed with the cerclage system. Static testing revealed that the revision of the short stem with the long stem caused a 2-fold (p < 0.001, ANOVA) increase of axial stiffness. In dynamic testing, the number of cycles to failure was 4 times (p < 0.001, ANOVA) higher with the long revision stem. Compared to locked plating cerclage wiring demonstrated a 26% more cycles to failure (p = 0.031, ANOVA). The load to failure was 91% larger (p < 0.001, ANOVA) with the long revision stem and 11% smaller with locked plating (p < 0.001, ANOVA). In conclusion, the present biomechanical study indicates that periprosthetic Vancouver B1 fractures can be sufficiently fixed by simple cerclage systems. Revision with a long replacement stem provides a superior mechanical stability regardless of type of osteosynthesis fixation and is therefore a viable method in Vancouver B1 cases. A disadvantage of the cerclage system compared to plating is that an increased subsidence of the short stem was observed.

Periprosthetic fracture fixation in osteoporotic bone

Fixation techniques of periprosthetic fractures are far from ideal although the number of this entity is rising. The presence of an intramedullary implant generates its own fracture characteristics since stiffness is altered along the bone shaft and certain implant combinations affect load resistance of the bone. Influencing factors are cement fixation of the implant, intramedullary locking and extramedullary or intramedullary localization of the implant and the cortical thickness of the surrounding bone. Cerclage wires are ideally suited to fix radially displaced fragments around an intramedullary implant but they are susceptible to axial and torsional load. Screws should be added if these forces have to be neutralized. Stability of the screw fixation itself can be enhanced by embracement configuration around the intramedullary implant. Poor bone stock quality, often being present in metaphyseal areas limits screw fixation. Cement augmentation is an attractive option in this field to enhance screw purchase.

Locking compression plate versus revision-prosthesis for Vancouver type B2 periprosthetic femoral fractures after total hip arthroplasty

INTRODUCTION

Revision arthroplasty is currently the recommended treatment for periprosthetic femoral fractures after primary total hip arthroplasty (THA) and stem loosening (Vancouver B2). However, open reduction and internal fixation (ORIF) utilizing locking compression plate (LCP) might be an effective treatment with a reduced surgical time and less complex procedure in a typically elderly patient collective with multiple comorbidities. The purpose of this study was to compare the functional and radiographic outcomes in two cohorts with Vancouver B2 periprosthetic femoral fractures after primary THA, treated either by ORIF with LCP fixation, or by revision arthroplasty utilizing a non-cemented long femoral stem.

MATERIALS AND METHODS

36 patients with Vancouver B2 periprosthetic femoral fractures following THA, who had been treated between 2000 and 2014, were reviewed. Eight fractures were treated with LCP fixation, fourteen fractures with the first-generation revision prosthesis (Helios), and fourteen fractures with the second-generation revision prosthesis (Hyperion). The patients were assessed clinically with the Parker mobility score and radiographically.

RESULTS

A total of ten males and 26 females formed the basis of this report with an average age of 81 years (range, 64 to 96 years). All fractures treated with LCP fixation alone healed uneventfully and there were no signs of secondary stem migration, malalignement or plate breakage. The average surgical time was shorter in the ORIF cohort; however, the results were not statistically significant. The postoperative Parker mobility score at latest follow-up showed no difference between the groups.

CONCLUSIONS

According to the results of the current study, we conclude that the use of LCP fixation can be a sufficient option for the treatment of Vancouver B2 periprosthetic femoral fractures correspondingly with femoral stem loosening.

Enhancing fixation strength in periprosthetic femur fractures by orthogonal plating-A biomechanical study

Orthogonal plate osteosynthesis enhances fixation stability in periprosthetic femur fractures. Another option are locking attachment plates (LAP) allowing bicortical locking screw placement lateral to the prosthesis stem. Stability of lateral plate osteosynthesis with two LAP (2LAP) was compared to anterolateral orthogonal plate osteosynthesis (OP) with one LAP in a periprosthetic femur fracture model. In six pairs of fresh frozen human femora with cemented Charnley hip prosthesis, a transverse osteotomy was set distal to the tip of the prosthesis simulating a Vancouver type B1 fracture. Each pair was instrumented using a plate tensioner with either one lateral plate and two LAP, or two orthogonal anterolateral plates and one LAP. Stiffness was determined in a four-point-bending test prior to cyclic testing (2Hz) with physiologic profile and progressively increasing load up to catastrophic construct failure. Paired t-test and Wilcoxon-signed-rank test were used for statistical evaluation at a level of significance p = 0.05. The OP construct exhibited a significantly higher number of cycles and load to failure (39,627 cycles ± 4,056; 4,463 N ± 906) compared to the 2LAP construct (32,927 cycles ± 3,487; 3,793 N ± 849), p < 0.01. Mediolateral bending and torsional stiffness of the OP (1610 N/mm ± 249; 16.9 Nm/mm ± 6.3) were significantly higher compared to 2 LAP (1077 N/mm ± 189; 12.1 Nm/mm ± 3.9), p = 0.03 for both comparisons. Orthogonal plate osteosynthesis is a valuable option in periprosthetic fracture surgery, offering increased stability compared to a single lateral plate fixed with two LAP.

Periprosthetic femoral fractures--incidence, classification problems and the proposal of a modified classification scheme

INTRODUCTION

The increasing incidence of periprosthetic fractures correlates directly with the year-after-year increasing frequency of primary joint replacement surgery. The most common fracture localisation is the femur. The undisputed leader in frequency is the fracture that occurs around a total hip arthroplasty. Unfortunately, no general epidemiologic data exist dealing with exact fracture incidence numbers. Furthermore, existing classifications are lacking important information like time point of fracture occurrence, type of the implanted prosthesis and implantation technique (cemented vs. cementless). Additionally, information about mechanical quality of the bone structure and the fracture type are also missing in part.

METHODS

We scanned the literature for adequate and widely used classifications in the field of hip and knee arthroplasty. In a next step we analyzed those classification systems in order to find out to what extent they are able to describe the specific aspects of the fracture event. Therefore we compared the existing classifications and presented their most relevant emphasis. Furthermore, we looked at our own patient population to evaluate incidence of fracture occurrence over time and percentage of loosened components.

RESULTS

The existing classification systems address themselves specifically to the task of describing fracture localization and to some extent fracture type, or combine these two in order to calculate the possibility of loosening of the implanted prosthesis. Some of the important criteria like mechanical quality of the bone stock, primary implantation technique or time point of the prosthesis loosening (prior to or because of the fracture) remain ignored. The incidence of periprosthetic femur fractures at our department increased approximately 2.5 fold over the past two decades. The risk of suffering from a periprosthetic fracture was substantially higher after THA than after TKA. We observed a loose femoral component of the THA in about 45 % of the cases. Finally, we postulate the application of a modified classification for periprosthetic fractures as an alternative to the already published ones; not only for the femur, but also universally for all joints with an arthroplasty.

CONCLUSION

The classification that is introduced in this study allows, in our opinion, a differentiated reflection of the given post-traumatic pathologic changes and enables the description of the fracture itself according to a generally accepted fracture classification scheme.

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.

Management of periprosthetic femoral fractures following total hip arthroplasty: a review

PURPOSE

As the number of total hip arthroplasties (THAs) is increasing, the expected number of periprosthetic femur fractures is also expected to increase. As such, a thorough grasp of the evaluation and management of patients with periprosthetic femur fractures is imperative, and discussed in this review.

METHODS

This review discusses the epidemiology, classification, and management of periprosthetic femur fractures in an evidence-based fashion.

RESULTS

Periprosthetic fracture management starts with assessing stem stability and bone quality. Well-fixed stems require fracture fixation without stem revision, while loose stems require revision THA.

CONCLUSIONS

Periprosthetic femoral fractures after primary total hip arthroplasty are a complex and clinically challenging issue. The treatment must be based on the fracture, the prosthesis, and the patient (Table 1). The Vancouver classification is not only helpful in classifying the fractures, but also in guiding the treatment. In general, well-fixed stems require open reduction and internal fixation, whereas loose stems require revision arthroplasty.

The biomechanical effect of bone quality and fracture topography on locking plate fixation in periprosthetic femoral fractures

Optimal management of periprosthetic femoral fractures (PFF) around a well fixed prosthesis (Vancouver B1) remains controversial as adequate fixation needs to be achieved without compromising the stability of the prosthesis. The aim of this study was to highlight the effect of bone quality i.e. canal thickness ratio (CTR), and fracture topography i.e. fracture angle and its position in relation to the stem, on the biomechanics of a locking plate for a Vancouver B1 fracture. A previously corroborated simplified finite element model of a femur with a cemented total hip replacement stem was used in this study. Canal thickness ratio (CTR) and fracture topography were altered in several models and the effect of these variations on the von Mises stress on the locking plate as well as the fracture displacement was studied. Increasing the CTR led to reduction of the von Mises stress on the locking plate as well as the fracture movement. In respect to the fracture angle with the medial cortex, it was shown that acute angles resulted in lower von Mises stress on the plate as opposed to obtuse angles. Furthermore, acute fracture angles resulted in lower fracture displacement compared to the other fractures considered here. Fractures around the tip of the stem had the same biomechanical effect on the locking plate. However, fractures more distal to the stem led to subsequent increase of stress, strain, and fracture displacement. Results highlight that in good bone quality and acute fracture angles, single locking plate fixation is perhaps an appropriate management method. On the contrary, for poor bone quality and obtuse fracture angles alternative management methods might be required as the fixation might be under higher risk of failure. Clinical studies for the management of PFF are required to further support our findings.

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.

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

The aim of this study is to assess the biomechanical advantage of adding strut allograft and the effect of its position on the construct in Vancouver type B1 fractures. Fifteen forth-generation synthetic femurs were used and created a fracture model at the tip of prosthesis, and subsequently fixated with a lateral plate only, lateral plate and medial strut, lateral plate and anterior strut. Rotational and axial tests were performed. In all loading tests, the plate with medial strut group was stiffer than the other constructs and had higher failure load values and had less displacement in the fracture site. A combination of a plate with a medial strut allograft provides more mechanical stability on periprosthetic femoral fractures near the tip of a total hip arthroplasty.