Better Axial Stiffness of a Bicortical Screw Construct Compared to a Cable Construct for Comminuted Vancouver B1 Proximal Femoral Fractures

What's New in Periprosthetic Femur Fractures?

BACKGROUND

Periprosthetic femur fracture (PFF) is one of the most common indications for reoperation following total hip arthroplasty.

METHODS/RESULTS

This article provides a review of a symposium on PFF that was presented at the American Association of Hip and Knee Surgeons 2023 annual meeting, including an overview of the Vancouver classification and its implications on treatment and subsequent complications, an updated approach to the management of intraoperative fractures, and finally, contemporary strategies for both osteosynthesis as well as revision arthroplasty for PFFs.

CONCLUSION

As the incidence of PPF continues to increase, arthroplasty and trauma surgeons must be prepared to address this challenging complication with a contemporary understanding of the treatment options and their outcomes.

Drilling the cement mantle in well-fixed periprosthetic femur fractures is not associated with arthroplasty-related complications

OBJECTIVE

To determine if screw fixation across a cement mantle is safe and effective during plate fixation of well-fixed periprosthetic femur fractures.

DESIGN

Retrospective cohort study.

SETTING

Academic Level I Trauma Center.

PATIENTS

Twenty-eight patients with AO/OTA 32A[B1] or 32A[C] periprosthetic femur fractures treated with open reduction and internal plate and screw fixation after cemented or uncemented hip arthroplasty.

INTERVENTION

Screw placement into the cement mantle during internal fixation.

OUTCOME MEASUREMENTS

Primary outcome was revision arthroplasty for aseptic loosening. Secondary outcomes included radiographic evidence of aseptic loosening, infection, nonunion, implant failure, and overall reoperation rate.

RESULTS

There were 28 patients who met inclusion criteria. A total of 9 patients had screws placed in the cement mantle while the remaining 19 patients had screws placed around an uncemented stem. At a mean of 3.7-year follow-up, there were no cases of revision arthroplasty or aseptic loosening in either group. There were no significant differences in rates of infection, nonunion, implant failure, or reoperation rate between patients who had screw placement into a cement mantle vs around an uncemented stem.

CONCLUSION

Drilling into the cement mantle during fixation of a periprosthetic femur fracture around a well-fixed cemented hip stem appears safe and effective. When possible, surgeons can consider bicortical screws around a cemented stem, given the biomechanical advantages over unicortical screw or cerclage fixation. Larger prospective trials confirming the safety of this technique are warranted prior to routine implementation.

LEVEL OF EVIDENCE

III.

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.

Biomechanics of Osteoporotic Fracture Fixation

PURPOSE OF REVIEW

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

RECENT FINDINGS

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

Biomechanics of Periprosthetic Fixation: Plates, Nails, Cables, and Allografts

Periprosthetic fractures (PPFs) present unique challenges to orthopaedic surgeons in terms of limited cortical fixation options, poor bone quality, cement mantles, and stress risers introduced from the prosthesis. Various fixation strategies have been used in PPFs including the use of intramedullary nails, locked plates, unicortical locking screws, cerclage wires and cables, double-plating techniques, and allograft struts. Here, we will review the biomechanics of various fixation strategies used in PPFs.

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.

Use of Locking Plate and Strut Onlay Allografts for Periprosthetic Fracture Around Well-Fixed Femoral Components

BACKGROUND

The purpose of this study was to determine: validated clinical and radiographic outcomes of periprosthetic femoral fractures around stable hip implants treated with plate fixation and additional cortical strut onlay allografts without revision of the stem; radiographic signs of fracture healing; allograft-to-host bone union; resorption of cortical strut allograft; and frequency of complications.

METHODS

At our institute, 24 patients (25 hips) were identified with Vancouver type B1 fracture at the tip of the femoral stem and one patient (one hip) was identified with a Vancouver type C fracture of the femur. All these fractures were treated with combined use of locking plate fixation and cortical strut onlay allografts. There were 18 women and 7 men, with an average age of 63 years. Harris hip score and University of California, Los Angeles activity score were used to assess postoperative function. The average duration of follow-up was 3.7 years (range, 1-7 years).

RESULTS

Harris hip score at final review was 86 points (range, 65-95 points). University of California, Los Angele activity score averaged 5.8 ± 1.3 point (range, 3.5-10 points) at final follow-up. All but 2 patients returned to their preoperative functional level within 1 year. Twenty-three of 26 hips had fracture union following the first operation. Three hips were failed to obtain fixation because of insufficient length of plate and allograft. Cortical strut onlay allografts were incorporated in the host femur in all hips by one year. Minor resorption of allograft was noticed, but there was no failure of any of the cortical strut allografts.

CONCLUSION

The cortical strut onlay allografts facilitated the mechanical stability and the biological fracture healing in addition to plate fixation.

Plate fixation in periprosthetic femur fractures Vancouver type B1-Trochanteric hook plate or subtrochanterical bicortical locking?

INTRODUCTION

Proximal plate fixation in periprosthetic femur fractures can be improved by plate anchorage in the greater trochanter (lateral tension band principle) or bicortical locking screw placement beside the prosthesis stem in an embracement configuration. Both concepts were compared in a biomechanical test using a femoral hook plate (hook) or a locking attachment plate (LAP).

METHODS

After bone mineral density (BMD) measurement in the greater trochanter, six pairs of fresh frozen human femora were assigned to two groups and instrumented with cemented hip endoprostheses. A transverse osteotomy was set distal to the tip of the prosthesis, simulating a Vancouver B1 fracture. Each pair was instrumented using a plate tensioner with either hook or LAP construct. Cyclic testing (2Hz) with physiologic profile and monotonically increasing load was performed until catastrophic failure. Plate stiffness was compared in a four-point-bending-test. Paired student's-t-test was used for statistical evaluation (p<0.05).

RESULTS

Mean BMD was 250mgHA/ccm±47. The hook construct exhibited a significantly (p=0.015) lower number of cycles and load to failure (26'177cycles±2777; 3'118N±778) correlating significantly with BMD (R²=0.83; p=0.04) compared to the LAP construct (37'423cycles±5'299; 4'242N±1'030) (R²=0.71;p=0.11). BMD was a significant covariate (p=0.01). Plate stiffness was in a comparable range (hook Plate 468N/mm±7; LCP 445N/mm±6).

CONCLUSION

Subtrochanterically placed LAP provides an increased fixation strength under repetitive loading compared to hook plate fixation in the greater trochanter. Trochanteric fixation is highly BMD dependent and may be restricted to major greater trochanteric involvement requiring stabilization.

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.