How to enhance the stability of locking plate fixation of proximal humerus fractures? An overview of current biomechanical and clinical data

doi:10.1016/j.injury.2015.04.020

Injury

Volume 46, Issue 7, July 2015, Pages 1207-1214

https://doi.org/10.1016/j.injury.2015.04.020 Get rights and content

Abstract

Background

The complication rate after locking plate fixation of proximal humerus fractures is high. In addition to low bone mineral density, a lack of medial support has been identified as one of the most important factors accounting for mechanical instability. As a result of the high failure rate, different strategies have been developed to enhance the mechanical stability of locking plate fixation of proximal humerus fractures. The aim of the present article is to give an overview of the current biomechanical and clinical studies that focus on how to increase the stability of locking plate fixation of proximal humerus fractures.

Methods

A comprehensive search of the Medline databases using specific search terms with regard to the stability of locking plate fixation of proximal humerus fractures was performed. After screening of the articles for eligibility, they were subdivided according to clinical and biomechanical aspects.

Results

Medial support screws, filling of bone voids and screw-tip augmentation with bone cement as well as the application of bone grafts are currently the most frequently assessed and performed methods. Although the evidence is weak, all of the mentioned strategies appear to have a positive effect on achieving and maintaining a stable reduction even of complex fractures.

Conclusion

Further clinical studies with a higher number of patients and a higher level of evidence are required to develop a standardised treatment algorithm with regard to cement augmentation and bone grafting. Although these measures are likely to have a stabilising effect on locking plate fixation, its general use cannot be fully recommended yet.

Introduction

Fractures of the proximal humerus are the fourth-most common fracture among geriatric patients after distal radius, proximal femur and vertebral fractures [1], [2]. Because the geriatric population is growing continuously, an increase in the incidence of these fractures should be expected [3]. Locking plate fixation is a standard procedure for the treatment of proximal humerus fractures [4]. However, complication rates of up to 49% have been reported [4], [5], [6], [7], [8], [9]. A low bone mineral density (BMD) and a lack of medial support have been identified as the two most important factors for the stability of locking plate fixation [10], [11], [12]. In their clinical study, Krappinger et al. demonstrated that low BMD is associated with a significantly higher risk of implant failure and loss of reduction after locking plate fixation [12]. With regard to medial support, Gardner et al. were the first to describe the correlation between a lack of medial support and a loss of reduction after fixation of proximal humerus fractures [10]. Accordingly, Jung et al. found significantly worse results after locking plate fixation of fractures with medial comminution [13].

To overcome these problems, many efforts have been made in recent years, and clinical and biomechanical studies have focussed on three principles to increase the stability of locking plate fixation of proximal humerus fractures: augmentation of screw tips in regions of low BMD, the use of medial support screws (calcar screws) and autograft or allograft augmentation in fractures with comminution of the medial column [14], [15], [16], [17], [18], [19], [20], [21], [22], [23], [24], [25], [26].

The aim of the present article is to give an overview of current biomechanical and clinical studies that focus on how to increase the stability of locking plate fixation of proximal humerus fractures in order to help develop a standardised treatment strategy for this complex and challenging injury.

Section snippets

Methods

The Medline database was searched using the keyword ‘proximal humerus fracture’ in combination with either ‘stability’, ‘medial support’, ‘augmentation’, ‘cement’, ‘bone graft’, ‘autograft’ or ‘allograft’. Only those articles published in the English language were included. After screening, the eligible articles were separated into three groups: (1) medial support screws, (2) cement augmentation and (3) bone grafts. In addition, they were further subdivided into biomechanical and clinical

Medial support screws

Gardner et al. suggested parameters to define whether medial support of a proximal humerus fracture was restored during surgery [10]. A fracture is considered to have medial support if (1) the medial column is intact, anatomically reduced and not comminuted; (2) the shaft is impacted into the head fragment; or (3) an oblique locking screw is placed directly into the inferomedial quadrant of the proximal humeral head fragment to within 5 mm of the subchondral bone. Because medial comminution can

Discussion

The aim of this overview was to present current biomechanical and clinical data on measures to enhance the stability of locking plate fixation of proximal humerus fractures. Literature research revealed that the use of medial support screws, cement augmentation and bone grafts are currently the most frequently used and assessed tools to increase the stability of locking plate constructs. Although the evidence is low and prospective randomised clinical trials on the use of either technique are

Source of funding

None.

Conflict of interest statement

All other authors, their immediate families and any research foundation with which they are affiliated did not receive any financial payments or other benefits from any commercial entity related to the subject of this article.

There is no conflict of interest.

References (51)

A.H. Warriner et al.
Which fractures are most attributable to osteoporosis?
J Clin Epidemiol
(2011)
M. Königshausen et al.
Clinical outcome and complications using a polyaxial locking plate in the treatment of displaced proximal humerus fractures. A reliable system?
Injury
(2012)
R.C. Sproul et al.
A systematic review of locking plate fixation of proximal humerus fractures
Injury
(2011)
C. Thanasas et al.
Treatment of proximal humerus fractures with locking plates: a systematic review
J Shoulder Elbow Surg
(2009)
D. Krappinger et al.
Predicting failure after surgical fixation of proximal humerus fractures
Injury
(2011)
K.A. Egol et al.
Fracture site augmentation with calcium phosphate cement reduces screw penetration after open reduction-internal fixation of proximal humeral fractures
J Shoulder Elbow Surg
(2012)
S. Kathrein et al.
Biomechanical comparison of an angular stable plate with augmented and non-augmented screws in a newly developed shoulder test bench
Clin Biomech (Bristol, Avon)
(2013)
J.C. Katthagen et al.
Biomechanical effects of calcar screws and bone block augmentation on medial support in locked plating of proximal humeral fractures
Clin Biomech (Bristol, Avon)
(2014)
S.H. Kim et al.
Outcomes for four-part proximal humerus fractures treated with a locking compression plate and an autologous iliac bone impaction graft
Injury
(2012)
F. Matassi et al.
Locking plate and fibular allograft augmentation in unstable fractures of proximal humerus
Injury
(2012)

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Biomechanical design optimization of proximal humerus locked plates: A review
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Proximal humerus locked plates (PHLPs) are widely used for fracture surgery. Yet, non-union, malunion, infection, avascular necrosis, screw cut-out (i.e., perforation), fixation failure, and re-operation occur. Most biomechanical investigators compare a specific PHLP configuration to other implants like non-locked plates, nails, wires, and arthroplasties. However, it is unknown whether the PHLP configuration is biomechanically optimal according to some well-known biomechanical criteria. Therefore, this is the first review of the systematic optimization of plate and/or screw design variables for improved PHLP biomechanical performance.
The PubMed website was searched for papers using the terms “proximal humerus” or “shoulder” plus “biomechanics/biomechanical” plus “locked/locking plates”. PHLP papers were included if they were (a) optimization studies that systematically varied plate and screw variables to determine their influence on PHLP's biomechanical performance; (b) focused on plate and screw variables rather than augmentation techniques (i.e., extra implants, bone struts, or cement); (c) published after the year 2000 signaling the commercial availability of locked plate technology; and (d) written in English.
The 41 eligible papers involved experimental testing and/or finite element modeling. Plate variables investigated by these papers were geometry, material, and/or position, while screw variables studied were number, distribution, angle, size, and/or threads. Numerical outcomes given by these papers included stiffness, strength, fracture motion, bone and implant stress, and/or the number of loading cycles to failure. But, no paper fully optimized any plate or screw variable for a PHLP by simultaneously applying four well-established biomechanical criteria: (a) allow controlled fracture motion for early callus generation; (b) reduce bone and implant stress below the material's ultimate stress to prevent failure; (c) maintain sufficient bone-plate interface stress to reduce bone resorption (i.e., stress shielding); and (d) increase the number of loading cycles before failure for a clinically beneficial lifespan (i.e., fatigue life). Finally, this review made suggestions for future work, identified clinical implications, and assessed the quality of the papers reviewed.
Applying biomechanical optimization criteria can assist biomedical engineers in designing or evaluating PHLPs, so orthopaedic surgeons can have superior PHLP constructs for clinical use.
Surgical treatment of complex proximal humeral fractures in elderly patients: a matched-pair analysis of angular-stable plating vs. reverse shoulder arthroplasty
2020, Journal of Shoulder and Elbow Surgery
To date, there is a lack of consensus regarding the type of surgical treatment for complex proximal humeral fractures (PHFs) in elderly patients, especially between joint preservation and joint replacement techniques.
We matched 60 patients (aged 73.2 ± 6.4 years) with complex PHFs in terms of sex, age, and Charlson Comorbidity Index, who underwent locking-plate open reduction–internal fixation (ORIF) or reverse shoulder arthroplasty (RSA) (2011-2017). Postoperative range of motion and functional outcome were assessed using the American Shoulder and Elbow Surgeons shoulder score, Oxford Shoulder Score, Constant-Murley score, and Disabilities of the Arm, Shoulder and Hand score at a mean follow-up of 49 months (ORIF group) and 38 months (RSA group). Complications and unplanned revision surgery were recorded, and all radiographs were analyzed.
ORIF resulted in numerically, although not statistically significantly, greater mean shoulder motion vs. RSA. Significantly better outcome was reported for the Oxford Shoulder Score (P = .034) and Disabilities of the Arm, Shoulder and Hand score (P = .026) in the ORIF group, although no significant differences were observed in the American Shoulder and Elbow Surgeons shoulder score and Constant-Murley score. The complication rate (30% vs. 10%) and revision rate (20% vs. 3%) were significantly higher in the ORIF group (P = .028), with patients who had complications or required revision having worse functional results.
Favorable results are achievable through both angular-stable plating and RSA. Although ORIF may be associated with a superior functional outcome, exceeding the minimal clinically important difference, RSA was linked to significantly fewer complications and revisions.
Cross-elements to enhance fixation in osteoporotic bone with application to proximal humeral locking plates: a biomechanical study
2020, Journal of Shoulder and Elbow Surgery
Proximal humeral fractures occur predominantly in elderly, osteoporotic individuals, especially women, with surgery performed in one-fifth. Proximal humeral locking plates are the gold standard operative treatment; however, complications are frequent, partially because of poor screw purchase in osteoporotic bone. A new method uses threaded posts through which threaded cross-elements orthogonally pass to create a 3-dimensional scaffold for bone engagement. We examined the pullout characteristics of the posts with (1 or 2) or without the cross-elements and tested 2 types of 3.5-mm cortical locking screws for comparison.
Low-density closed-cell polyurethane foam served as a model osteoporotic bone substrate. Following implantation in the substrate, the devices were axially loaded by a mechanical test system. Quantities of interest included failure mode, peak load, displacement to peak load, initial stiffness, and work expended.
The post groups outperformed the 3.5-mm screw groups, as expected. Relative to posts with no cross-elements, 1 and 2 cross-elements increased the peak load by 29% and 87% and increased the work to peak load by 126% and 343%, respectively. After reaching peak load, 1 and 2 cross-elements increased the work-resistance to further displacement by 158% and 330%, respectively.
Cross-elements significantly increased the ability of the threaded posts to resist axial displacement from a model osteoporotic bone substrate. This suggests that posts, used in conjunction with cross-elements, have the potential to enhance the stability of proximal humeral locking plates in osteoporotic bone.
The influence of biplanar reduction and surgeon experience on proximal humerus fractures treated with ORIF
2020, Injury
Treatment for proximal humerus fractures remains controversial. Studies of open reduction and internal fixation (ORIF) rarely account for reduction quality, while surgeon experience and sagittal plane reduction remain unstudied. In a retrospective case series analysis of AO/OTA C-type proximal humerus fractures treated with ORIF using a locking plate, we hypothesized that reduction quality would be associated with outcome, and reductions would improve with experience.
We retrospectively identified 41 3- and 4-part proximal humerus fractures treated with ORIF by a single orthopaedic traumatologist. Two blinded traumatologists assessed injury and post-operative radiographs for medial calcar disruption and five measures of deformity. Major complications and functional outcome were assessed.
Outcome by ASES score was similar to previous reports (mean 73.6, std dev 22.5). Eleven of 35 patients (31.4%) with greater than six months follow-up experienced a complication. Post-reduction sagittal HSa<25° (RR = =9.44, p = =0.024) and medial calcar disruption (RR = =3.82, p = =0.009) were associated with complications. Post-reduction coronal and sagittal HSa improved with experience (p < 0.001 and p = =0.032, respectively) as did the likelihood of overall anatomic reduction (p = =0.006). ROC analysis found a threshold for superior reduction quality after 23 cases (AUC = =0.873, p < 0.001).
Sagittal reduction quality and medial calcar disruption were associated with complications. Additionally, reduction quality improved with experience. Future studies of proximal humerus ORIF should include multiplanar assessments of reduction while accounting for surgeon experience.
Operative management of proximal humeral fractures using combined osteosynthesis: A narrative review
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Quality of life, functional and radiological outcomes of treatment of three-part and four-part proximal humerus fractures with locking plates and comparison in young versus older than 70 years: a retrospective cohort study
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ReviewHow to enhance the stability of locking plate fixation of proximal humerus fractures? An overview of current biomechanical and clinical data

Abstract

Background

Methods

Results

Conclusion

Introduction

Section snippets

Methods

Medial support screws

Discussion

Source of funding

Conflict of interest statement

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Review
How to enhance the stability of locking plate fixation of proximal humerus fractures? An overview of current biomechanical and clinical data