The effect of in situ augmentation on implant anchorage in proximal humeral head fractures

doi:10.1016/j.injury.2012.07.003

Injury

Volume 43, Issue 10, October 2012, Pages 1759-1763

https://doi.org/10.1016/j.injury.2012.07.003 Get rights and content

Abstract

Introduction

Fracture fixation in patients suffering from osteoporosis is difficult as sufficient implant anchorage is not always possible. One method to enhance implant anchorage is implant/screw augmentation with PMMA-cement. The present study investigated the feasibility of implant augmentation with PMMA-cement to enhance implant anchorage in the proximal humerus.

Materials and methods

A simulated three part humeral head fracture was stabilised with an angular stable plating system in 12 pairs of humeri using six head screws. In the augmentation group the proximal four screws were treated with four cannulated screws, each augmented with 0.5 ml of PMMA-cement, whereas the contra lateral side served as a non-augmented control. Specimens were loaded in varus-bending or axial-rotation using a cyclic loading protocol with increasing load magnitude until failure of the osteosynthesis occurred.

Results

Augmented specimens showed a significant higher number of load cycles until failure than non-augment specimens (varus-bending: 8516 (SD 951.6) vs. 5583 (SD 2273.6), P = 0.014; axial-rotation: 3316 (SD 348.8) vs. 2050 (SD 656.5), P = 0.003). Non-augmented specimens showed a positive correlation of load cycles until failure and measured bone mineral density (varus-bending: r = 0.893, P = 0.016; axial-rotation: r = 0.753, P = 0.084), whereas no correlation was present in augmented specimens (varus-bending: r = 0,258, P = 0.621; axial-rotation r = 0.127, P = 0.810).

Conclusion

These findings suggest that augmentation of cannulated screws is a feasible method to enhance implant/screw anchorage in the humeral head. The improvement of screw purchase is increasing with decreasing bone mineral density.

Introduction

One of the “hot topics” in orthopaedic and trauma surgery is the ideal reduction and fixation of proximal humeral fractures in osteoporotic and elderly patients. Despite extensive research neither a treatment of choice nor a “gold standard implant” became apparent in the last years. The development and introduction of locking plates and intramedullary nails for the proximal humerus led to promising results but complication rates remained rather high.1, 2, 3, 4, 5 Implant related complications, in particular loss of fixation caused by failed screw purchase due to reduced bone quality poses a great challenge for the surgeon.6, 7, 8, 9, 10 Independently of the surgical technique and the used implant Krappinger et al.,¹¹ reported a failure rate of 19.4% after surgical fixation of proximal humerus fractures and identified local BMD, age and anatomic reduction with medial cortical support as main factors causing unfavourable outcome.

An established method to enhance screw or implant purchase in reduced bone stock is implant augmentation with PMMA-cement (polymethylmetacrylat). Generally, this technique involves four steps, placement of the implant (1), removal of the implant (2), PMMA cement injection (3) and repositioning of the implant (4). In recent years introduction of cannulated implants allowed placement and fixation of the implant with subsequent in situ augmentation under fluoroscopic control.

In the field of proximal femur fractures PMMA augmentation technique showed improved anchorage in modified dynamic hip screws (DHS).12, 13, 14 More recently it has been shown, that in situ augmentation through the cannulated blade of the proximal femur nail antirotation (PFNa) significantly improved implant anchorage and the number of load cycles to cut out.15, 16 In spine surgery, augmentation of pedicle screws is a commonly used method to enhance screw purchase in osteoporotic vertebrae.17, 18, 19, 20

The aim of the present study was to evaluate improvement of implant anchorage with augmented screw fixation in three part humeral fractures under cyclic loading in varus bending and axial rotation.

Section snippets

Specimens

Twelve pairs of fresh frozen human humeri (mean age 70.67, SD 12.94, 6 female, 6 male) were used for biomechanical testing. A qCT scan (GE Lightspeed VCT 16, Milwaukee, USA) was performed to rule out relevant pathologies and to determine the local bone mineral density (BMD). The BMD of the humeral head was assessed using the method described by Krappinger et al.,²¹ including a European Forearm Phantom (EFP) calibration (EFP-Phantom, QRM GmbH, Möhrendorf, Deutschland). Specimens were cleaned

Results

All results are presented as mean values with standard deviation.

In the varus bending load case all specimens failed by loosening of the screws in the humeral head and subsequent varus tilting of the head relative to the plate. The conventional non-augmented group reached 5583 (SD 2273.6) load cycles until failure, while the contralateral augmented group failed after 8516 (SD 951.6) cycles (P = 0.014). This corresponded to a loading of 245.4 N and 348.1 N for the non-augmented and augmented group,

Discussion

One of the main problems of osteoporotic humerus fractures is to achieve sufficient screw purchase and fixation allowing early mobilisation and physiotherapy1, 6, 23 and to prevent implant related complications.

The aim of the present biomechanical study was to investigate if PMMA augmentation of cannulated screws is a feasible method to enhance screw purchase in the humeral head. It has been shown, that for both investigated load cases (varus bending and axial rotation) augmented specimens

Conclusion

From a biomechanical point of view the use of in situ PMMA augmented cannulated screws in the humeral head is a favourable method to enhance implant anchorage. Augmentation with PMMA-cement seems to be only reasonable in cases with low BMD values.

Conflict of interest

None of the authors has received or will receive benefits for personal or professional use from a commercial party related directly or indirectly to the subject of this article.

Acknowledgements

This work was financially supported by the AO-Foundation within the Clinical Priority Programme “Fracture Fixation in Osteoporotic Bone” (CPP-FFOB). Furthermore the authors would like to thank Synthes GmbH, Oberdorf, Switzerland for providing the implants as well as the PMMA-cement for the study free of charge.

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Second generation locked plating of proximal humerus fractures—a prospective multicentre observational study
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Cited by (84)

Fibula allograft in complex three-part and four-part proximal humeral fractures in active patients, a matched case-control study
2024, JSES International
About 20% of proximal humerus fractures (PHFs) are unstable and/or markedly displaced and therefore require surgery. Locking plate fixation after anatomical reduction has become the current treatment of choice for these fractures in the active population. However, studies have shown complication rates up to 36%, such as loss of reduction and avascular necrosis. To date, data from literature are inconclusive on outcomes following the use of an intramedullary fibula allograft in PHFs, possibly due to the case mix. It is hypothesized that the use of a fibula allograft is beneficial to prevent secondary displacement of the fracture in cases where the medial hinge is markedly displaced and unstable, resulting in better clinical and patient reported outcomes.
In this multicenter matched cohort study, patients with an unstable, displaced PHF, including anatomic neck fractures and significantly displaced surgical neck fractures, were included. Patients that were treated with a locking plate augmented with a fibula allograft were matched to patients who had undergone locking plate reconstruction without the allograft. The matches were made based on fracture characteristics, age, and performance status. Functional outcomes, Patient Reported Outcome Measures, complications, and radiographic results were compared.
Twelve patients with fibula allograft augmented osteosyntheses were included and matched to 12 control patients. The mean age was 58 years in the fibula allograft group compared to 62 years in the control group. Minimum follow-up was 12 months. Disability of the Arm Shoulder and Hand score, Constant Shoulder score, abduction, and external rotation were significantly better in the fibula allograft group (17.4 ± 8.6 vs. 26.1 ± 19.2, P = .048; 16.5 ± 11.5 vs. 19.8 ± 16.5 P = .040; mean 127° ± 38° vs. mean 92° ± 49° P = −.045; 50° ± 21° vs. mean 26° ± 23°, P = .004). There was no statistically significant difference in the Oxford Shoulder score between groups (P = .105). The Visual Analog Scale was not significantly different between groups (3.1 ± 1.8 vs. 1.6 ± 1.9, P = .439). Radiographic union was reached in 11 patients of the fibula allograft group compared to 8 in the control group (P = .317). The complication rate was twice as high in the control group (3 vs. 7).
Additional support of the medial hinge in unstable PHFs with a locking plate in combination with a fibula allograft appears to create a more stable construct without compromising the viability of the articular surface of the head. The use of a fibula allograft in selected complex cases could therefore result in better clinical outcomes with lower complication rates.
Experimental magnesium phosphate cement paste increases torque of trochanteric fixation nail advanced™ blades in human femoral heads
2023, Clinical Biomechanics
The use of polymethylmethacrylate cement for in-situ implant augmentation has considerable disadvantages: it is potentially cytotoxic, exothermic and non-degradable. Therefore, the primary aim of this study was to develop a magnesium phosphate cement which meets the requirements for in-situ implant augmentation as an alternative. Secondly, this experimental cement was compared to commercial bone cements in a biomechanical test set-up using augmented femoral head blades.
A total of 40 human femoral heads were obtained from patients who underwent total hip arthroplasty. After bone mineral density was quantified, specimens were assigned to four treatment groups. A blade of the Trochanteric Fixation Nail Advanced™ was inserted into each specimen and augmented with either Traumacem™ V+, Paste-CPC, the experimental magnesium phosphate cement or no cement. A rotational load-to-failure-test (0° to 90°) was performed.
A conventional two-component magnesium phosphate cement failed in-situ implant augmentation consistently due to filter pressing. Only a glycerol-based magnesium phosphate paste was suitable for the augmentation of femoral head blades. While the blades augmented with Traumacem™ V+ yielded the highest maximum torque overall (22.1 Nm), the blades augmented with Paste-CPC and the magnesium phosphate paste also showed higher maximum torque values (15.8 and 12.8 Nm) than the control group (10.8 Nm).
This study shows for the first time the development of a degradable magnesium phosphate cement paste which fulfills the requirements for in-situ implant augmentation. Simultaneously, a 48% increase in stability is demonstrated for a scenario where implant anchorage is difficult in osteoporotic bone.
[Translated article] Comparative biomechanical study of two configurations of cemented screws in a simulated proximal humerus fracture fixed with locking plate
2023, Revista Espanola de Cirugia Ortopedica y Traumatologia
Screw tip augmentation with bone cement for fixation of osteoporotic proximal humerus fractures seems to improve stability and to decrease the rate of complications related to implant failure. However, the optimal augmentation combinations are unknown. The aim of this study was to assess the relative stability of two augmentations combinations under axial compression load in a simulated proximal humerus fractures fixed with locking plate.
A surgical neck osteotomy was created in five pairs of embalmed humeri with a mean age of 74 years (range 46–93 years), secured with a stainless-steel locking-compression plate. In each pair of humeri, on the right humerus were cemented the screws A and E, and in the contralateral side were cemented screws B and D of the locking plate. The specimens were first tested cyclically in axial compression for 6000 cycles to evaluate interfragmentary motion (dynamic study). At the end of the cycling test, the specimens were loaded in compression force simulating varus bending with increasing load magnitude until failure of the construct (static study).
There were no significant differences in interfragmentary motion between the two configurations of cemented screws in the dynamic study (p = 0.463). When tested to failure, the configuration of cemented screws in lines B and D demonstrated higher compression load to failure (2218 N vs. 2105, p = 0.901) and higher stiffness (125 N/mm vs. 106 N/mm, p = 0.672). However, no statistically significant differences were reported in any of these variables.
In simulated proximal humerus fractures, the configuration of the cemented screws does not influence the implant stability when a low-energy cyclical load is applied. Cementing the screws in rows B and D provides similar strength to the previously proposed cemented screws configuration and could avoid complications observed in clinical studies.
La utilización de tornillos cementados en la fijación interna de fracturas de húmero proximal con placas bloqueadas parece mejorar la estabilidad del implante y disminuir las complicaciones asociadas al fracaso de síntesis. Sin embargo, la combinación óptima de tornillos cementados se desconoce. El objetivo de este estudio fue analizar la estabilidad relativa de 2 configuraciones de tornillos cementados sometidos a una fuerza de compresión axial en una fractura simulada de húmero proximal.
Se realizó una osteotomía del cuello quirúrgico en 5 pares de húmeros embalsamados con una edad media de 74 años (rango: 46-93), fijados con una placa de acero inoxidable con tornillos bloqueados. En cada par de húmeros, en el húmero derecho se cementaron los tornillos A y E, y en el lado contralateral se cementaron los tornillos B y D. Cada espécimen fue testado inicialmente mediante una carga cíclica de compresión axial durante 6.000 ciclos para evaluar el movimiento interfragmentario (estudio dinámico). Al final de la prueba, los especímenes se sometieron a una carga de compresión axial progresiva para medir la rigidez de la construcción (estudio estático).
No se encontraron diferencias estadísticamente significativas en la movilidad interfragmentaria entre las 2 configuraciones de tornillos cementados en el estudio dinámico (p = 0,463). Cuando se sometieron a rotura, los especímenes con tornillos cementados en las hileras B y D presentaron una carga de rotura mayor (2218 N vs. 2105; p = 0,901) y una mayor rigidez (125 vs. 106 N/mm; p = 0,672); sin embargo, ninguna de estas diferencias fue estadísticamente significativa.
La configuración de los tornillos cementados utilizadas en este estudio no influyen en la estabilidad del implante cuando se aplica una carga cíclica de baja energía. La cementación de los tornillos de las hileras B y D proporciona una resistencia similar a la cementación de los tornillos A y E.
Comparative biomechanical study of two configurations of cemented screws in a simulated proximal humerus fracture fixed with locking plate
2023, Revista Espanola de Cirugia Ortopedica y Traumatologia
La utilización de tornillos cementados en la fijación interna de fracturas de húmero proximal con placas bloqueadas parece mejorar la estabilidad del implante y disminuir las complicaciones asociadas al fracaso de síntesis. Sin embargo, la combinación óptima de tornillos cementados se desconoce. El objetivo de este estudio fue analizar la estabilidad relativa de dos configuraciones de tornillos cementados sometidos a una fuerza de compresión axial en una fractura simulada de húmero proximal.
Se realizó una osteotomía del cuello quirúrgico en cinco pares de húmeros embalsamados con una edad media de 74 años (rango 46-93), fijados con una placa de acero inoxidable con tornillos bloqueados. En cada par de húmeros, en el húmero derecho se cementaron los tornillos A y E, y en el lado contralateral se cementaron los tornillos B y D. Cada espécimen fue testado inicialmente mediante una carga cíclica de compresión axial durante 6.000 ciclos para evaluar el movimiento interfragmentario (estudio dinámico). Al final de la prueba, los especímenes se sometieron a una carga de compresión axial progresiva para medir la rigidez de la construcción (estudio estático).
No se encontraron diferencias estadísticamente significativas en la movilidad interfragmentaria entre las dos configuraciones de tornillos cementados en el estudio dinámico (p = 0,463). Cuando se sometieron a rotura, los especímenes con tornillos cementados en las hileras B y D presentaron una carga de rotura mayor (2218N vs. 2105, p = 0,901) y una mayor rigidez (125 N/mm vs. 106 N/mm, p = 0,672); sin embargo, ninguna de estas diferencias fue estadísticamente significativa.
La configuración de los tornillos cementados utilizadas en este estudio no influyen en la estabilidad del implante cuando se aplica una carga cíclica de baja energía. La cementación de los tornillos de las hileras B y D proporciona una resistencia similar a la cementación de los tornillos A y E.
Screw tip augmentation with bone cement for fixation of osteoporotic proximal humerus fractures seems to improve stability and to decrease the rate of complications related to implant failure. However, the optimal augmentation combinations are unknown. The aim of this study was to assess the relative stability of two augmentations combinations under axial compression load in a simulated proximal humerus fractures fixed with locking plate.
A surgical neck osteotomy was created in five pairs of embalmed humeri with a mean age of 74 years (range 46–93 years), secured with a stainless-steel locking-compression plate. In each pair of humeri, on the right humerus were cemented the screws A and E, and in the contralateral side were cemented screws B and D of the locking plate. The specimens were first tested cyclically in axial compression for 6,000 cycles to evaluate interfragmentary motion (dynamic study). At the end of the cycling test, the specimens were loaded in compression force simulating varus bending with increasing load magnitude until failure of the construct (static study).
There were no significant differences in interfragmentary motion between the two configurations of cemented screws in the dynamic study (p = 0.463). When tested to failure, the configuration of cemented screws in lines B and D demonstrated higher compression load to failure (2218N vs. 2105, p = 0.901) and higher stiffness (125 N/mm vs. 106 N/mm, p = 0.672). However, no statistically significant differences were reported in any of these variables.
In simulated proximal humerus fractures, the configuration of the cemented screws does not influence the implant stability when a low-energy cyclical load is applied. Cementing the screws in rows B and D provides similar strength to the previously proposed cemented screws configuration and could avoid complications observed in clinical studies.
Reversed windshield-wiper effect leads to failure of cement-augmented pedicle screw: Biomechanical mechanism analysis by finite element experiment
2023, Heliyon
The failure mode of cement-augmented pedicle screw (CAPS) was different from common pedicle screw. No biomechanical study of this failure mode named as “reversed windshield-wiper effect” was reported. To investigate the mechanisms underlying this failure mode, a series of finite element models of CAPS and PS were modified on L4 osseous model. Nine models were created according to the cement volume at 0.5 mL interval (range: 1–5 mL). Pullout load and cranio-caudal loads were applied on the screws. Stress and instantaneous rotation center (IRC) of the vertebra were observed. Under cranio-caudal load, the stress concentrated on the screw tip and pedicle region. The maximal stress (MS) at the screw tip region was +2.143 MPa higher than pedicle region. With cement volume increasing, the maximal stress (MS) at the screw tip region decreased dramatically, while MS at pedicle region was not obviously affected. As dose increased to 1.5 mL, the MS at pedicle region became higher than screw tip region and the maximal stress difference was observed at 3.5 mL. IRC of the vertebra located at the facet joint region in PS model. While IRC in CAPS models shifted anteriorly closer to the vertebral body with the increasing of cement volume. Under axial pull-out load, the maximal stress (MS) of cancellous bone in CAPS models was 29.53–50.04% lower than that 2.228 MPa in PS model. MS in the screw-bone interface did not change significantly with cement volume increasing. Therefore, the possible mechanism is that anterior shift of IRC and the negative difference value of MS between screw tip and pedicle region due to cement augmentation, leading to the screw rotate around the cement-screw complex as the fulcrum point.
Primary stability of cement augmentation in locking plate fixation for proximal humeral fractures: A comparison of absorbable versus non-absorbable cement
2022, Clinical Biomechanics
Cement augmentation has been suggested to increase the stability of screw anchoring in osteoporotic humeral fractures. Initial results are promising but may be jeopardized by cement leakage into the joint and difficult implant removal. Absorbable cement might have advantages in this regard, but it is unclear if the primary stability of both techniques is equivalent to each other. Therefore, this study aimed to compare its primary stability with that of non-absorbable cement augmentation.
Nineteen cadaveric humeri with two-part fracture models were treated with locking plate osteosynthesis and cement augmentation using either absorbable calcium phosphate cement (group 1) or polymethylmethacrylate (group 2). Fracture movement, stiffness, failure mode, and ultimate load under cyclic compressive loading were examined and compared between the groups.
The absolute and relative stiffness values in group 1 were significantly smaller than those in group 2 after 50 cycles (group 1: 114 ± 38 N/mm and 94 ± 8% vs. group 2: 188 ± 71 N/mm and 106 ± 9%; p₅₀ = 0.022), 2000 cycles (group 1: 97 ± 34 N/mm and 81 ± 15% vs. group 2: 153 ± 47 N/mm and 88 ± 15%; p₂₀₀₀ = 0.028), and 5000 cycles (group 1: 98 ± 40 N/mm and 81 ± 22% vs. group 2: 158 ± 40 N/mm and 92 ± 16%; p₅₀₀₀ = 0.028). The failure load was not statistically significantly different between the groups.
Although the PMAA group showed higher values for absolute and relative stiffness, no statistically significant difference was found in the primary stability between absorbable and non-absorbable cement augmentation supporting plate osteosynthesis in proximal humeral fractures. In view of the potential advantages of bio-absorbable cement during the healing process, its use should be considered for the augmentation and stabilization of osteoporotic fractures.

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The effect of in situ augmentation on implant anchorage in proximal humeral head fractures

Abstract

Introduction

Materials and methods

Results

Conclusion

Introduction

Section snippets

Specimens

Results

Discussion

Conclusion

Conflict of interest

Acknowledgements

Clinical Biomechanics (Bristol, Avon)

Clinical Biomechanics (Bristol, Avon)

Clinical Biomechanics (Bristol, Avon)

Clinical Biomechanics (Bristol, Avon)

Clinical Biomechanics (Bristol, Avon)

Are polyaxially locked screws advantageous in the plate osteosynthesis of proximal humeral fractures in the elderly? A prospective randomized clinical observational study

Journal of Orthopaedic Trauma

Biomechanical in vitro assessment of fixed angle plating using a new concept of locking for the treatment of osteoporotic proximal humerus fractures

International Orthopaedics

Second generation locked plating of proximal humerus fractures—a prospective multicentre observational study

International Orthopaedics

Biomechanical evaluation of two-part surgical neck fractures of the humerus fixed by an angular stable locked intramedullary nail

Journal of Orthopaedic Trauma

Biomechanical analysis of blade plate versus locking plate fixation for a proximal humerus fracture: comparison using cadaveric and synthetic humeri

Journal of Orthopaedic Trauma

Two-part surgical neck fractures of the proximal part of the humerus. A biomechanical evaluation of two fixation techniques

Journal of Bone and Joint Surgery

Open reduction and internal fixation of proximal humerus fractures using a proximal humeral locked plate: a prospective multicenter analysis

Journal of Orthopaedic Trauma

Open reduction and internal fixation of proximal humeral fractures with use of the locking proximal humerus plate. Results of a prospective, multicenter, observational study

Journal of Bone and Joint Surgery

Analysis of efficacy and failure in proximal humerus fractures treated with locking plates

Journal of Orthopaedic Trauma