Less invasive stabilisation system (LISS) for the treatment of periprosthetic femoral fractures: a 3-year follow-up

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.

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.

[Periprosthetic and interimplant femoral fractures: Biomechanical analysis]

BACKGROUND

The requirements for treatment of femoral fractures are increasing with the rising age of the patients. The aim of this study was to evaluate femoral stiffness and the fracture risk after inserting different implants and implant combinations.

METHODS

A total of 48 cadaveric femors were harvested and 8 groups were randomized on the basis of the bone mineral density (BMD). Different osteosyntheses following prosthetic stem implantation (hip and knee prostheses) were performed and compared with native femurs. All specimens were biomechanically tested in a four-point bending until fracture.

RESULTS

The insertion of a femoral stem decreases the stiffness by approximately 33%. Ipsilateral retrograde nailing reduces the force to failure even more. This instable situation can be stabilized by a lateral locking compression plate. The most stable situation occurred in the presence of two cemented stems.

CONCLUSION

Taken together these results clearly indicate that a hip prosthesis significantly weakens the femur, whereas two stems produce the most stable situation at all. The situation of a hip prosthesis and an retrograde nail should be avoided or covered by a bridging-osteosynthesis. In clinical practice an extramedullary fixation technique for distal femoral fractures should be preferred.

The influence of the operation technique and implant used in the treatment of periprosthetic hip and interprosthetic femur fractures: a systematic literature review of 1571 cases

INTRODUCTION

A systematic literature review on periprosthetic/interprosthetic fracture fixation after hip arthroplasties was performed to summarize available clinical data. Operation techniques and implants used were evaluated as possible risk factors for outcomes.

MATERIALS AND METHODS

MEDLINE and Cochrane databases were searched. Articles describing patients with postoperative periprosthetic femur fractures sustained around a hip arthroplasty and with interprosthetic fractures treated with plates, nails, screws and/or cerclage were included. Considered articles were from 2000 or newer. Eligible abstracts were screened by two independent persons and discrepancies were resolved by consensus. Absolute numbers of complications and/or reoperation events along with their corresponding rates were calculated according to operation technique and type of implant. Relative risks of having a complication and/or a reoperation according to the operation technique and the type of implant used were estimated.

RESULTS

Available data from 49 prospective and retrospective studies were analyzed. Of 1574 fractures, 81.7 % were treated with plating. For 83.0 % of all fractures, an open approach was applied. The overall complication rate was 14.3 %. Fixation failure and nonunion were most often reported (fixation failure: 4.4 %; nonunion: 3.9 %). Nonunion and refracture occurred more often after open approaches than after minimal invasive osteosynthesis (nonunion: 4.5 vs. 0.0 %, p = 0.001; refracture: 3.8 vs. 0.6 %. p = 0.024). The relative risk for nonunion was 11.9 (95 % CI 4.5-31.5) times higher (p < 0.0001) for non-locking plates (13.0 %) than for locking plates (1.1 %).

CONCLUSIONS

The clinical evidence of published studies dealing with periprosthetic/interprosthetic fractures after hip arthroplasty is generally low. This literature search suggested higher rates of nonunion and refracture after an open approach and a higher risk of nonunion for non-locking plates compared to locking plates. Based on the available clinical evidence, no treatment recommendations can be given.

Periprosthetic fractures around the femoral stem: overcoming challenges and avoiding pitfalls

Management of periprosthetic fractures around the femoral stem after total hip arthroplasty (THA) represents a significant challenge and optimal treatment remains controversial. The most common treatment paradigm involves treating fractures around a well-fixed stem with osteosynthesis, whereas fractures around a loose stem require revision arthroplasty and those with poor bone require augmentation with bone graft. Paradoxically, the literature reports a higher rate of failure for osteosynthesis around prostheses considered to be well-fixed. Such a high rate of poor outcomes may result not only from difficult fracture fixation and compromised biologic healing, but also from unrecognized peri-implant pathology. Therefore, proper preoperative and intraoperative evaluation is key, and a subset of patients may benefit from alternative management. We review the appropriate methods for evaluation and treatment of Vancouver type B fractures with particular emphasis on avoiding missteps that can lead to failure.

[Ipsilateral THA after stemmed TKA: Risk of interprosthetic fracture?]

BACKGROUND

There is an increasing number of patients who have undergone stemmed total knee arthroplasty and total hip arthroplasty in the same leg. These patients may be at increased risk of periprosthetic and interprostethic fracture. Etiology and the potential therapy strategies are not well represented in the current literature.

OBJECTIVES

Determination of the risk factors for interprosthetic fractures and possible prevention.

MATERIALS AND METHODS

We performed a review of the literature and additionally a survey among experts (members of the German Association for Arthroplasty [AE]) to investigate the risk and the necessity for a preventive internal fixation.

RESULTS

There are only a few biomechanical studies. The interprosthetic distance seems to have little influence on the fracture risk, but the thickness of the cortex and the cortical area at the diaphysis seems to be important. The value of a bridging osteosynthesis remains uncertain. Ninety experts took part in the survey. The risk of fracture risk was estimated to be only slight to medium. Opinions regarding the necessity of preventive internal fixation were heterogeneous.

CONCLUSIONS

The indication for preventive internal fixation could be derived neither from the literature nor from the survey of experts. The thickness of the cortex and co-morbidities (osteoporosis, tendency to fall, and medication) seem to be more important than the interprosthetic distance.

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.

Periprosthetic femoral fractures in total hip arthroplasty

Periprosthetic fractures in total hip arthroplasty (THA) are a significant problem facing hip surgeons, and were responsible for revision surgery in 9% of single stage revision THAs recorded in the National Joint Registry of England and Wales (NJR) in 2012; the 5th most common cause after aseptic loosening, osteolysis, pain and dislocation. The incidence has increased along with the number of THAs performed. Implants and techniques of THA continue to evolve, surgical indications are expanding and the number performed annually continues to rise. Furthermore, patients are undergoing THA earlier and living longer, leading to a rise in the average number of years at risk for periprosthetic fracture. In this review we will discuss the epidemiology of femoral periprosthetic fractures, their prevention, classification and the evidence base for their treatment.

Surgical fixation of Vancouver type B1 periprosthetic femur fractures: a systematic review

OBJECTIVES

Vancouver type B1 periprosthetic femur fractures occur around a stable implant and are typically treated with open reduction and internal fixation (ORIF). Different fixation techniques are described in the literature, and there is a lack of consensus regarding the best operative fixation strategy. The purpose of this investigation was to systematically review and compare the most commonly used fixation strategies for these fractures.

DATA SOURCES

A database search was performed using PubMed, MEDLINE, and Cochrane databases to identify studies published in English language from 1985 to 2013.

STUDY SELECTION

Articles with a minimum of 5 patients with type B1 periprosthetic femur fractures and containing outcome data regarding nonunion, malunion, infection, and reoperation rate were included.

DATA EXTRACTION

Studies were analyzed and categorized into 4 groups: group 1: ORIF with cortical strut allografts alone, group 2: ORIF with cable plate/compression plates alone, group 3: ORIF with cable plate/compression plates and cortical strut allograft, group 4: ORIF with locking plates alone. Individual patient outcomes were extracted for each study and pooled for each of the 4 groups. Data analysis was performed comparing rates of nonunion, malunion, hardware failure, infection, and reoperation.

DATA SYNTHESIS

Data were analyzed using Review Manager and SAS 9.3.

CONCLUSIONS

In total, 333 patients identified with an overall rate of 5% nonunion, 6% malunion, 5% infection, 4% hardware failure, 9% reoperation, and 15% total complications. When comparing outcomes for different modes of fixation, compared with cable plate/compression plate systems, locking plates had a significantly higher rate of nonunion (3% vs. 9% P = 0.02) and a trend toward a higher rate of hardware failure (2% vs. 7%, P = 0.07). There are limitations to this study, and further investigation with high-quality randomized controlled trials is needed to effectively compare treatment strategies.

Mono- versus polyaxial locking plates in distal femur fractures - a biomechanical comparison of the Non-Contact-Bridging- (NCB) and the PERILOC-plate

Background

The aim of this cadaveric study was to compare a polyaxial (NCB®, Zimmer) to a fixed-angle monoaxial locking plate (PERILOC®, Smith & Nephew) in comminuted fractures of the distal femur regarding stability of the construct. Up to date there is no published biomechanical data concerning polyaxial plating in cadaveric distal femurs.

Methods

Fourteen formalin fixed femora were scanned by dual-energy x-ray absorptiometry. As fracture model an unstable supracondylar comminuted fracture was simulated. Fractures were pairwise randomly fixed either with a mono- (group A) or a polyaxial (group B) distal femur plate. The samples were tested in a servohydraulic mechanical testing system starting with an axial loading of 200 N following an increase of 200 N in every step with 500 cycles in every sequence up to a maximum of 2 000 N. The end points were implant failure or relevant loss of reduction. Data records included for each specimen time, number of cycles, axial load and axial displacement. Statistical analysis was performed using the exact Wilcoxon signed rank test.

Results

The mean donor age at the time of death was 75 years. The bone mass density (BMD) of the femurs in both groups was comparable and showed no statistically significant differences. Five bones failed before reaching the maximum applied force of 2000 N. Distribution curves of all samples in both groups, showing the plastic deformation in relation to the axial force, showed no statistically significant differences.

Conclusions

Operative stabilization of distal femur fractures can be successfully and equally well achieved using either a monoaxial or a polyaxial locking plate. Polyaxial screw fixation may have advantages if intramedullary implants are present.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2474-15-369) contains supplementary material, which is available to authorized users.

Clinical and radiological results of locking plate fixation for periprosthetic femoral fractures around hip arthroplasties: a retrospective multi-center study

BACKGROUND

Osteosynthesis of periprosthetic femoral fractures around hip arthroplasties is challenging, and locking plate fixation has been found to be a reasonable treatment. However, there is a paucity of evidence of the extent to which patients recover their activities of daily living (ADL). The purpose of this study was to study the clinical results, particularly recovery of ADL, radiological results, and potential complications arising from the use of locking plate fixation for periprosthetic femoral fractures around hip arthroplasties.

METHODS

We conducted a retrospective, multi-center study. Patients with periprosthetic femoral fractures around hip arthroplasties who were treated by osteosynthesis with use of locking plates and who underwent follow-up for at least 6 months postoperatively were enrolled in the study. For each patient, recovery of ADL, in terms of social and ambulatory recovery and Parker mobility score, were compared before fracture and at last follow-up. Postoperative complications were investigated. Bony union, loss of reduction, and malunion were assessed radiologically.

RESULTS

Thirty-two patients were enrolled in this study. Mean follow-up was 25.1 months. For 84.4, 68.8, and 53.1% of patients, respectively, social status, ambulation, and Parker mobility score at last follow-up were determined to be equal to that before the fracture. Bony union was observed for 30 patients within the follow-up period. Four patients had not achieved bony union 6 months postoperatively. There was no loss of reduction, malunion, or implant breakage, and no infection. For one patient each, partial pullout of the locking screws and a supracondylar fracture at the plate end were observed, and additional surgery was required.

CONCLUSIONS

Our results reveal that locking plate fixation provided sufficient stability for satisfactory recovery of ADL for most elderly patients with periprosthetic femoral fractures around hip arthroplasties.

Treatment of distal femur fractures in a regional Australian hospital

AIM: To review our outcomes and compare the results of the Less Invasive Stabilization System (LISS) to other implants for distal femur fracture management at a regional Australian hospital.

METHODS: The LISS is a novel implant for the management of distal femur fractures. It is, however, technically demanding and treatment results have not yet been assessed outside tertiary centres. Twenty-seven patients with 28 distal femur fractures who had been managed surgically at the Mackay Base Hospital from January 2004 to December 2010 were retrospectively enrolled and assessed clinically and radiologically. Outcomes were union, pain, Lysholm score, knee range of motion, and complication rates.

RESULTS: Twenty fractures were managed with the LISS and eight fractures were managed with alternative implants. Analysis of the surgical techniques revealed that 11 fractures managed with the LISS were performed according to the recommended principles (LISS-R) and 9 were not (LISS-N). Union occurred in 67.9% of fractures overall: 9/11 (82%) in the LISS-R group vs 5/9 (56%) in the LISS-N group and 5/8 (62.5%) in the alternative implant group. There was no statistically significant difference between pain, Lysholm score, and complication rates between the groups. However, there was a trend towards the LISS-R group having superior outcomes which were clinically significant. There was a statistically significant greater range of median knee flexion in the LISS-R group with compared to the LISS-N group (P = 0.0143) and compared with the alternative implant group (P = 0.0454).

CONCLUSION: The trends towards the benefits of the LISS procedure when correctly applied would suggest that not only should the LISS procedure be performed for distal femur fractures, but the correct principle of insertion is important in improving the patient’s outcome.

Treatment results of a periprosthetic femoral fracture case series: treatment method for Vancouver type b2 fractures can be customized

Background

Currently, an algorithmic approach for deciding treatment options according to the Vancouver classification is widely used for treatment of periprosthetic femoral fractures after hip arthroplasty. However, this treatment algorithm based on the Vancouver classification lacks consideration of patient physiology and surgeon's experience (judgment), which are also important for deciding treatment options. The purpose of this study was to assess the treatment results and discuss the treatment options using a case series.

Methods

Eighteen consecutive cases with periprosthetic femoral fractures after total hip arthroplasty and hemiarthroplasty were retrospectively reviewed. A locking compression plate system was used for osteosynthesis during the study period. The fracture type was determined by the Vancouver classification. The treatment algorithm based on the Vancouver classification was generally applied, but was modified in some cases according to the surgeon's judgment. The reasons for modification of the treatment algorithm were investigated. Mobility status, ambulatory status, and social status were assessed before the fracture and at the latest follow-up. Radiological results including bony union and stem stability were also evaluated.

Results

Thirteen cases were treated by osteosynthesis, two by revision arthroplasty and three by conservative treatment. Four cases of type B2 fractures with a loose stem, in which revision arthroplasty is recommended according to the Vancouver classification, were treated by other options. Of these, three were treated by osteosynthesis and one was treated conservatively. The reasons why the three cases were treated by osteosynthesis were technical difficulty associated with performance of revision arthroplasty owing to severe central migration of an Austin-Moore implant in one case and subsequent severe hip contracture and low activity in two cases. The reasons for the conservative treatment in the remaining case were low activity, low-grade pain, previous wiring around the fracture and light weight. All patients obtained primary bony union and almost fully regained their prior activities.

Conclusions

We suggest reaching a decision regarding treatment methods of periprosthetic femoral fractures by following the algorithmic approach of the Vancouver classification in addition to the assessment of each patient's hip joint pathology, physical status and activity, especially for type B2 fractures. The customized treatments demonstrated favorable overall results.

A systematic review of open reduction and internal fixation of periprosthetic femur fractures with or without allograft strut, cerclage, and locked plates

Few comparative studies exist for open reduction and internal fixation of Vancouver B1 and C fractures. We therefore performed a systematic review of fractures treated with or without an allograft strut, and using various fixation techniques. Thirty-seven manuscripts including 682 fractures were identified between 1992 and 2012. Percent union was similar for Vancouver B1 fractures treated with or without an allograft strut (90.7% vs. 91.5%). Time to union (4.4 vs. 6.6 months) and deep infection (3.8% vs. 8.3%) were increased with use of allograft struts. Percent union and time to union were unaffected by plate type or use of cerclage. We conclude that due to increased infection and time to union, allograft struts should be used cautiously during operative treatment of Vancouver B1 factures.

[Treatment of periprosthetic and peri-implant fractures : modern plate osteosynthesis procedures]

Periprosthetic fractures are increasing not only due to the demographic development with high life expectancy, the increase in osteoporosis and increased prosthesis implantation but also due to increased activity of the elderly population. The therapeutic algorithms are manifold but general valid rules for severe fractures are not available. The most commonly occurring periprosthetic fractures are proximal and distal femoral fractures but in the clinical routine fractures of the tibial head, ankle, shoulder, elbow and on the borders to other implants (peri-implant fractures) and complex interprosthetic fractures are being seen increasingly more. It is to be expected that in the mid-term further options, such as cement augmentation of cannulated polyaxial locking screws will extend the portfolio of implants for treatment of periprosthetic fractures. The aim of this review article is to present the new procedures for osteosynthesis of periprosthetic fractures.

Locking plate fixation for Vancouver B1 periprosthetic femoral fractures: a critical analysis of 135 cases

PURPOSE

The overall incidence of periprosthetic femoral fractures (PPF) is between 0.1 and 6 % of all total hip arthroplasties. Locking compression plates (LCP) have been used for the treatment of Vancouver B1 PPFs with variable results. The aim of this study is to examine the literature on locking plate failure rates, mode and reasons for failure.

METHODOLOGY

A literature search was conducted for studies reporting the management of PPF of the femur with LCP fixation. The primary medical search engines used for the study were Ovid MEDLINE and EMBASE databases up to August 2012.

RESULTS

Twelve studies were identified, reporting overall union rates of 91 % in 135 fractures. Only 7 (5 %) fractures required revision surgery due to plate fracture (5) or pull out (2). Important trends in plate complications included: stress riser at the end of the plate, stress concentration in the fracture area due to rigid fixation, early loading and absence of cortical strut grafting for biological support when needed.

CONCLUSION

LCP has been used successfully in the management of Vancouver B1 PPF. However, potential areas of improvement include, leaving the fracture site free of locking screws, therefore, not disturbing the soft tissue envelope around the fracture and also reducing plate stiffness. Adding cortical strut allografts to improve stability and bone quality, if needed, may also improve outcome. Limitations in the use of strut grafts or transverse fractures below the tip of the stem that cannot be controlled with single or double plating may require long stem revision to achieve axial stability.

NCB-plating in the treatment of geriatric and periprosthetic femoral fractures

BACKGROUND

The aim of this study is the presentation of the polyaxial locking NCB-plate in the treatment of femoral fractures, especially in elderly patients and in proximity of a prosthetic implant. The reduction and fixation of these fractures is a challenging surgical procedure with high complication rates reported up to 40%.

PATIENTS AND METHODS

A total of 72 patients with femoral fractures had polyaxial locking plate osteosynthesis. Indications included fractures of the shaft and around an implant. Concerning surgical procedures, three different standardized techniques were performed: (1) minimally invasive with percutaneous distal insertion using a targeting device; (2) mini-open with additional cerclage wire via the same approach and (3) a conventional open reduction and internal fixation. Data collection included intraoperative data and early complications at 6, 24 and 52 weeks. Fifty-two patients had an implant or prosthesis in situ. Thirty-three patients were treated by technique (1), 32 patients had mini-open surgery and seven patients conventional open surgery.

RESULTS

Thirty-nine patients attended clinical follow-up after 52 weeks. Twenty-two patients were interviewed by telephone, two were untraceable and nine patients had died. Bony consolidation without secondary loss of reduction was confirmed after 52 weeks in all patients but two. Plate breakage occurred in these two at 25 and 31 weeks after surgery due to non-union. Implant related complications (17% in total) lead to surgical revision in five other cases: two deep wound infections as well as three minor revisions. When itemizing complications according to surgical technique used, most major complications occurred following open surgery.

CONCLUSION

The availability of polyaxial locking implants widened the range of indications for plate fixation in femoral fractures. The advantages of the polyaxial locking implant combined with minimally invasive surgical technique contribute to successful management of this population category. Early revision rate is noticeably lower compared to similar procedures.

LEVEL OF EVIDENCE

IV retrospective series.

Angulated locking plate in periprosthetic proximal femur fractures: biomechanical testing of a new prototype plate

INTRODUCTION

To improve proximal plate fixation of periprosthetic femur fractures, a prototype locking plate with proximal posterior angulated screw positioning was developed and biomechanically tested.

METHODS

Twelve fresh frozen, bone mineral density matched human femora, instrumented with cemented hip endoprosthesis were osteotomized simulating a Vancouver B1 fracture. Specimens were fixed proximally with monocortical (LCP) or angulated bicortical (A-LCP) head-locking screws. Biomechanical testing comprised quasi-static axial bending and torsion and cyclic axial loading until catastrophic failure with motion tracking.

RESULTS

Axial bending and torsional stiffness of the A-LCP construct were (1,633 N/mm ± 548 standard deviation (SD); 0.75 Nm/deg ± 0.23 SD) at the beginning and (1,368 N/mm ± 650 SD; 0.67 Nm/deg ± 0.25 SD) after 10,000 cycles compared to the LCP construct (1,402 N/mm ± 272 SD; 0.54 Nm/deg ± 0.19 SD) at the beginning and (1,029 N/mm ± 387 SD; 0.45 Nm/deg ± 0.15) after 10,000 cycles. Relative movements for medial bending and axial translation differed significantly between the constructs after 5,000 cycles (A-LCP 2.09° ± 0.57 SD; LCP 5.02° ± 4.04 SD; p = 0.02; A-LCP 1.25 mm ± 0.33 SD; LCP 2.81 mm ± 2.32 SD; p = 0.02) and after 15,000 cycles (A-LCP 2.96° ± 0.70; LCP 6.52° ± 2.31; p = 0.01; A-LCP 1.68 mm ± 0.32; LCP 3.14 mm ± 0.68; p = 0.01). Cycles to failure (criterion 2 mm axial translation) differed significantly between A-LCP (15,500 ± 2,828 SD) and LCP construct (5,417 ± 7,236 SD), p = 0.03.

CONCLUSION

Bicortical angulated screw positioning showed less interfragmentary osteotomy movement and improves osteosynthesis in periprosthetic fractures.

The locking attachment plate for proximal fixation of periprosthetic femur fractures--a biomechanical comparison of two techniques

PURPOSE

Mechanical properties of a locking attachment plate construct (LAP-LCP), allowing bicortical screw placement laterally to the prosthesis stem, are compared to a cerclage-LCP construct.

METHODS

Eight right synthetic femora with implanted uncemented hip endoprosthesis were cut distally and fixed with LCP, monocortical locking screws and either LAP (n = 4) or cerclage (n = 4). Cyclic testing was performed with monotonically increasing sinusoidal load until failure. Relative movements at the plate-femur interface were registered by motion tracking. Statistical differences were detected by unpaired t-test and general linear model repeated measures.

RESULTS

Stiffness of the LAP-LCP was significantly higher at the beginning (875.4 N/mm ± 29.8) and after 5000 cycles (1213.0 N/mm ± 101.1) compared to the cerclage-LCP (644.96 N/mm ± 50.1 and 851.9 N/mm ± 81.9), with p = 0.013. Relative movements for AP-bending (B) and axial translation (T) of the LAP-LCP at the beginning (0.07° ± 0.02, 0.20 mm ± 0.08), after 500 cycles (0.16° ± 0.10, 0.26 mm ± 0.07) and after 5000 cycles (0.26° ± 0.11, 0.31 mm ± 0.07) differed significantly from the cerclage-LCP (beg.: 0.26° ± 0.04, 0.28 mm ± 0.05; 500 cyc: 0.47° ± 0.03, 0.53 mm ± 0.07; 5000 cyc.: 0.63° ± 0.18, 0.79 mm ± 0.13), with B: p = 0.02, T: p = 0.04. Relative movements for medial bending were not significantly different between the two constructs. Cycles to failure (criterion 1 mm axial translation) differed significantly between LAP-LCP (19,519 ± 1,758) and cerclage-LCP (11,265 ± 2,472), with p = 0.035.

CONCLUSIONS

Biomechanically, the LAP-LCP construct improves proximal fixation of periprosthetic fractures compared to the cerclage-LCP construct.

Periprosthetic femoral fractures treated by locked plating: feasibility assessment of the mini-invasive surgical option. A prospective series of 36 fractures

INTRODUCTION

The treatment of periprosthetic femoral fractures by conventional plating is associated with problems related to fracture union and eventual refracture. Additionally, locking nailing cannot be used in all cases because of the risk of malunion. To resolve these issues, locking plates have been proposed to combine the advantages of closed reduction and internal fixation while achieving a higher quality reduction with plate fixation.

HYPOTHESIS

Locking plates put into place by a mini-invasive surgical approach result in fixation without substantial misalignment or non-union.

PATIENTS AND METHODS

From June 2002 to December 2007 we prospectively treated 35 patients (one bilateral), 28 women and seven men with a fracture around the hip implant (21), around the knee (8), between the hip implant and the knee (2), between a trochanteric internal fixation device and the knee implant (5). The mean age was 76, (39-93). Internal fixation was always attempted by mini-invasive surgery using locking plate system with locking screws (Synthès™). Rehabilitation included immediate weight bearing with as much weight as the patient would tolerate. The preoperative Parker score was 5.25 (0-9).

RESULTS

There was one patient lost to follow-up, one early failure, and seven deaths (four of whom were included in the study group since their follow-up was at least 24 months) for a total of 31 fractures (30 patients), the mean follow-up for the series was 26 months (6-67). Twenty-six fixations were performed by mini-invasive approach and 10 through a conventional open surgery. Patients applied full weight (n=20), partial weight (n=3) or no weight for 6 weeks (n=13). Infections developed in two patients and there were three cases of mechanical failure. Fracture union was achieved in 35 out of 36 cases. More than 5° of misalignment was observed in five patients. Loosening of the implant did not occur in any patients during follow-up. The Parker score in patients seen at follow up was 4.3 (0-9).

DISCUSSION-CONCLUSION

Locking compression plates associated with a mini-invasive surgical approach result in a high rate of union (35/36) with no significant misalignment (only 5/36 cases of misalignment of more than 5°), no refractures (n=0) and a low rate of mechanical failure (3/36) while allowing full weight bearing in most cases (20/36). Locking plates for periprosthetic femoral fractures allow patients to begin walking again, with stable intermediate term results.

Nickel-titanium shape-memory sawtooth-arm embracing fixator for periprosthetic femoral fractures

PURPOSE

We reviewed data to determine outcomes for 21 consecutive Vancouver type B1 or type C periprosthetic fractures that we treated between 2001 and 2008 using a nickel-titanium shape-memory sawtooth-arm embracing fixator.

METHODS

The study participants were 12 men and 9 women (mean age, 70.8 years; range, 42-85 years). The average duration of follow-up monitoring was 39.7 months (range, 1-78 months). In five cases, cables and screws were used for further stabilisation. No bone grafting was performed for any of the patients.

RESULTS

Results were satisfactory, except for one patient who died one month after surgery from a cause unrelated to arthroplasty. Bone union was achieved in the remaining 20 cases within an average of 5.25 months. No implant failures or malunions occurred in any of the patients. The average Harris hip score at the final follow-up examination was 79.3 points.

CONCLUSIONS

Our results show that the embracing fixator is a valid alternative treatment for Vancouver type B1 or type C periprosthetic femoral fractures.

Intertrochanteric femoral fracture after hip resurfacing managed with a reverse distal femoral locking plate: a case report

Metal-on-metal hip resurfacing is a popular procedure for a select group of patients. A variety of surgical approaches are being utilised, each of which may be associated with specific complications. We describe an unusual complication following a Ganz trochanteric osteotomy approach, and the technique used to treat the subsequent periprosthetic fracture.

Treatment of periprosthetic femoral fractures with two different minimal invasive angle-stable plates: Biomechanical comparison studies on cadaveric bones

INTRODUCTION

The introduction of fixed-angle plate osteosynthesis techniques has provided us a further means to treat periprosthetic femoral fractures. The goal of this experimental study is to evaluate the biomechanical properties and stability of treated periprosthetic fractures when using two different plate systems, which vary in the locking mechanism and the screw placement (monocortical or bicortical) with respect to the prosthesis stem.

MATERIALS AND METHODS

Using five pairs of formalin-fixed femora, a Vancouver B1 periprosthetic fracture was treated either with a 13-hole LISS(®) titanium plate using four monocortical periprosthetic screws or with a non-contact bridging plate (NCB) DF(®) plate using bicortical angle-stable blocked screws positioned ventrally or dorsally to the prosthesis stem. Bones were loaded under axial and cyclic compression with a progressively increased load until failure. Displacement at the osteotomy gap was measured during loading using an ultra-sound measuring system.

RESULTS

The mean displacement in the region of the fracture gap was not significantly different at any time during the experiments for the two models. The mean force resulting in subsequent model failure was similar in both models; the failure morphology varied slightly between the models, however. Four of the five LISS(®) models exhibited either a tear-out of the monocortical screws or a decortication from the bony shaft of the cortical lamella surrounding the screws. On the other side, two of the NCB models showed macroscopically visible fissures along the osteosynthesis plates at the height of the osteotomy gap, and were hence considered implant failures. Only one NCB model showed tear-out of the bicortically placed screws.

CONCLUSION

Bicortical screw placement provides more stable anchoring when compared to monocortical screw fixation. However, in relation to the amount of motion at the osteotomy gap and to failure loads, stabilisation of periprosthetic femoral fractures can be equally well achieved using either the LISS(®) plate with periprosthetic monocortical screws or the NCB plate with poly-axially placed bicortical screws.

The effect of fixation technique on the stiffness of comminuted Vancouver B1 periprosthetic femur fractures

The purpose of this study was to evaluate the stiffness of 3 different constructs for the fixation of comminuted Vancouver B1 periprosthetic femoral shaft fractures: a single lateral locking plate, a single lateral locking plate plus an anterior strut allograft, and a lateral locking plate plus an anterior locking plate. The axial stiffness, lateral bending stiffness, and torsional stiffness of 10 synthetic periprosthetic femur fracture models were tested. Differences in stiffness between constructs were determined with a 1-way repeated-measures analysis of variance. Fixation technique was found to have a significant effect for all loading modalities (P < .0001). A lateral locked plate plus an anterior locked plate was significantly stiffer than the allograft that in turn was significantly stiffer than the single plate (P < .0001).

[Current status of minimally invasive plate osteosynthesis: specific part II]

With the increasing use of minimally invasive plate osteosynthesis in the last years almost every anatomical region was included in this new technique. Thus, it is not used any more for certain fractures and problematic areas, but also in fractures where it represents a challenge to established osteosynthesis techniques like intramedullary nailing or conventional plating. Therefore the challenge for the treating surgeon increased to find the right answer for the particularities of an individual fracture by choosing the optimal method. The most popular indications for the use of minimally invasive plate osteosynthesis are presented and the technical details are discussed. The possibilities for complications--in a common way and for specific fractures--are presented and discussed.

Type C periprosthetic fractures treated with locking plate fixation with a mean follow up of 2.5 years

BACKGROUND

Type C periprosthetic femoral fractures present fixation problems related to the extent of the fracture and the quality of the bone stock.

OBJECTIVES

The authors report a continuous and prospective series of type C periprosthetic femoral fractures to assess the mechanical stability of the femoral implant and the clinical outcome at the medium term.

MATERIAL AND METHODS

Between April 2004 and November 2006, we treated 17 patients (15 females, two males) presenting a prosthetic hip fracture (12 cases), between the hip prosthesis and the knee (one case), and with a knee prosthesis (four cases). All the implants had no sign of loosening at the time of fracture. The patients' mean age was 76.7 years (range, 39-93 years). Internal fixation was obtained with a locking compression plate (LCP) Synthes bridging the implant in place to prevent a weak zone. The rehabilitation protocol consisted in full weight bearing as much as possible.

RESULTS

The mean follow-up of the series was 31.5 months (range, 4-51 months). Four deaths were recorded during the follow-up. Minimally invasive surgery was performed in 15 patients.Total loading was possible immediately in 10 patients, partial loading at 20 kg in three patients,and no loading was possible until 6 weeks in four patients. Two infections and a bending-type mechanical complication of the plate secondary to a fall were observed. Consolidation was obtained in all cases with the appearance of callus formation beginning in the 6th week.

DISCUSSION

The technique used allies the principle of closed internal fixation (with preservation of the fracture hematoma) with mechanical stability. The screws locking to the plate warrant an internal fixator with increased stability that is sufficient for early loading with no risk of losing the secondary axis. Despite this increased rigidity, we did not observe any particular stress on the femoral implants. We recommend bridging the implant and spaced locking for better distribution of the stresses during loading. This hardware, with, if possible, insertion using a reduced approach, seems adapted to periprosthetic femoral fractures, particularly in the elderly.

LEVEL OF EVIDENCE

Level IV, prospective therapeutic study.

The clinical and radiological outcomes of the LISS plate for distal femoral fractures: a systematic review

PURPOSE

The purpose of this systematic review was to assess the literature evaluating the clinical and radiological outcomes following less invasive surgical stabilisation system (LISS) fixation of distal femoral fractures (AO 32/33).

METHODS

A review of EMBASE, Medline, CINAHL and AMED from their inception to November 2008, sources of grey literature and a pertinent hand search of specialist orthopaedic journals was undertaken.

RESULTS

Twenty-one studies assessing 663 patients with 694 fractures were reviewed. The findings suggest that the LISS system may be an appropriate fixation method for the management of distal femoral fractures. However, there remains a high incidence of loss of reduction (n=134; 19%), delayed or non-union (n=40; 6%) and implant failure (n=38; 5%). On analysis, such complications were largely confined to articles published before 2005, therefore during the infancy of the widespread clinical application of this trauma system. On critical appraisal, the evidence-base remains limited by recruiting small, under-powered sample sizes and poorly accounting for confounding variables such as osteoporosis, diabetes, multi-trauma and fracture classification.

CONCLUSION

Further study is required to assess the outcomes of LISS fixation in specific patient populations, and to compare the outcome of this fixation method to condylar plates and intrameduallary devices, to determine the optimal management strategy for this complex patient group.