Early results in the treatment of proximal humeral fractures with a polyaxial locking plate

Plate Fixation of Proximal Humerus Fractures: How to Get It Right and Future Directions for Improvement

PURPOSE OF REVIEW

Open reduction and internal fixation with locking plates (ORIF-LP) has been used for decades for the surgical management of proximal humerus fractures. Despite good outcomes have been widely published in the literature, unacceptably high rates of complications (up to 40%), many of them yielding poor outcomes and requiring reoperation (up to 25%), have also been reported, especially in elderly patients. Most common complications are related to implant failure, with intra-articular screw penetration as the most frequent and devastating.

RECENT FINDINGS

Advances in patient selection and surgical technique, and implementation of bone or cement augmentation, have been developed to hopefully decrease complication rates. Mayo-FJD Classification offers prognostic information that can aid in the decision-making process for proximal humeral fractures. Displaced valgus impacted fractures seem to be associated with well over a 10% rate of avascular necrosis after ORIF-LP. A principle-based and stepwise surgical technique combining anatomic reduction and a short screw configuration can provide good outcome in most patients, even the elderly, decreasing implant failures to less than 10%. Acrylic cement augmentation has the potential to further decrease implant failure rate to 1%. Reoperation rates are higher partly due to the need to remove hardware for painful subacromial conflict. However, no studies to date definitively demonstrated the superiority of ORIF-LP compared to non-operative treatment, intramedullary nailing, or reverse shoulder arthroplasty. ORIF-LP can provide good results for the surgical management of displaced proximal humerus fractures even in elderly patients provided adequate patient selection and a principle based and stepwise surgical technique, supplemented with bone graft or acrylic cement when needed. Poor outcomes and high complication and reoperation rates should be expected when these recommendations are not followed.

Locking Plates With Computationally Enhanced Screw Trajectories Provide Superior Biomechanical Fixation Stability of Complex Proximal Humerus Fractures

Joint-preserving surgical treatment of complex unstable proximal humerus fractures remains challenging, with high failure rates even following state-of-the-art locked plating. Enhancement of implants could help improve outcomes. By overcoming limitations of conventional biomechanical testing, finite element (FE) analysis enables design optimization but requires stringent validation. This study aimed to computationally enhance the design of an existing locking plate to provide superior fixation stability and evaluate the benefit experimentally in a matched-pair fashion. Further aims were the evaluation of instrumentation accuracy and its potential influence on the specimen-specific predictive ability of FE. Screw trajectories of an existing commercial plate were adjusted to reduce the predicted cyclic cut-out failure risk and define the enhanced (EH) implant design based on results of a previous parametric FE study using 19 left proximal humerus models (Set A). Superiority of EH versus the original (OG) design was tested using nine pairs of human proximal humeri (N = 18, Set B). Specimen-specific CT-based virtual preoperative planning defined osteotomies replicating a complex 3-part fracture and fixation with a locking plate using six screws. Bone specimens were prepared, osteotomized and instrumented according to the preoperative plan via a standardized procedure utilizing 3D-printed guides. Cut-out failure of OG and EH implant designs was compared in paired groups with both FE analysis and cyclic biomechanical testing. The computationally enhanced implant configuration achieved significantly more cycles to cut-out failure compared to the standard OG design (p < 0.01), confirming the significantly lower peri-implant bone strain predicted by FE for the EH versus OG groups (p < 0.001). The magnitude of instrumentation inaccuracies was small but had a significant effect on the predicted failure risk (p < 0.01). The sample-specific FE predictions strongly correlated with the experimental results (R2 = 0.70) when incorporating instrumentation inaccuracies. These findings demonstrate the power and validity of FE simulations in improving implant designs towards superior fixation stability of proximal humerus fractures. Computational optimization could be performed involving further implant features and help decrease failure rates. The results underline the importance of accurate surgical execution of implant fixations and the need for high consistency in validation studies.

Surgical Fixation of Three- and Four-Part Proximal Humeral Fractures Using the Proximal Humeral Interlocking System Plate

Introduction

The management of proximal humeral fractures ranges greatly from conservative management to surgical treatment. For those fractures requiring surgical treatment, internal fixation is the primary method. The aim of internal fixation is to achieve rigid fracture fixation until union occurs, return of shoulder range of motion, and minimise intra-and postoperative complications. The aim of this study was to evaluate the results of the Proximal Humeral Interlocking System Plate (PHILOS) used for the treatment of three-and four-part proximal humeral fractures.

Materials and methods

This study included 30 patients with a mean age of 54 years (range 20-80 years). Results were checked post-operatively with standard radiographs and clinical evaluation according to the Constant-Murley shoulder score. All patients were followed up for 12 months.

Results

Union was achieved in all patients with a mean neck/shaft angle of 130° (range 108°-150°). The mean Constant-Murley score at the final follow-up was 82.28 (range 67-96) correlating with good results. No patients developed an intraoperative or postoperative vascular injury, wound complications, or avascular necrosis of the humeral head.

Conclusion

Our study has shown that the surgical treatment of three- and four-part proximal humeral fractures with the use of the PHILOS plate leads to a good functional outcome. It has also demonstrated the PHILOS plate and is an effective system for fracture stabilisation provided the correct surgical technique is used with awareness of potential hardware complications.

Proximal humeral fracture locking plate fixation with anatomic reduction, and a short-and-cemented-screws configuration, dramatically reduces the implant related failure rate in elderly patients

Background

Multiple studies have reported an unacceptable implant-related complication rate in proximal humeral fractures treated with locking plates, particularly in older patients. Our objective was to compare the fracture fixation failure rates in elderly patients, after a dedicated technique for locking plate fixation with cement augmentation or without it.

Methods

A total of 168 open reduction and internal fixation with locking plates were performed for complex proximal humerus fractures by a single surgeon in 136 women and 32 men older than 65 years of age (average 76 years). Treatment groups included group 1 with noncemented screws (n = 90) and group 2 with cemented screws (n = 78). As per Mayo-FJD Classification, there were 74 (44%) varus posteromedial impaction, 41 (24%) algus impaction, 46 (28%) surgical neck, and 7 (4%) head dislocation injuries. A retrospective radiographic and a clinical analysis was performed.

Results

At a mean follow-up of 33 months, the implant failure rate was significantly lower in the cement augmentation group (1% vs. 8%, P = .03). The overall complication rate was 21% (25% group 1, 15% group 2; P = .1). Global avascular necrosis was associated with sustaining a valgus impacted fracture (P = .02 odds ratio 5.7), but not to augmentation. Partial avascular necrosis occurred only in patients treated with cemented screws (3.8%). The overall revision rate was 9% in both groups. Forward elevation was 126 ± 36 degrees and external rotation was 44 ± 19 degrees. The mean Constant score was 70 ± 15 in group 1 and 76 ± 15 in group 2 (P = .03).

Conclusion

Cement augmentation significantly decreased the rate of implant failure. Good results are expected for most patients treated with this technique.

Outcomes of Management of Proximal Humeral Fractures with Patient-Specific, Evidence-Based Treatment Algorithms

BACKGROUND

Previous studies have identified risk factors for different types of treatment of proximal humeral fracture (PHF) and allowed the development of a patient-specific, evidence-based treatment algorithm with the potential of improving overall outcomes and reducing complications. The purpose of this study was to evaluate the results and complications of treating PHF using this algorithmic approach.

METHODS

All patients with isolated PHF between 2014 and 2017 were included and prospectively followed. The initial treatment algorithm (Version 1 [V1]) based on patients' functional needs, bone quality, and type of fracture was refined after 2 years (Version 2 [V2]). Adherence to protocol, clinical outcomes, and complications were analyzed at a 1-year follow-up.

RESULTS

The study included 334 patients (mean age, 66 years; 68% female): 226 were treated nonoperatively; 65, with open reduction and internal fixation (ORIF); 39, with reverse total shoulder arthroplasty (RTSA); and 4, with hemiarthroplasty. At 1 year, the preinjury EuroQol 5-Dimension (EQ-5D) values were regained (0.88 and 0.89, respectively) and the mean relative Constant Score (CS) and Subjective Shoulder Value (SSV) (and standard deviation [SD]) were 96% ± 21% and 85% ± 16%. Overall complications and revision rates were 19% and 13%. Treatment conforming to the algorithm outperformed non-conforming treatment with respect to relative CS (97% versus 88%, p = 0.016), complication rates (16.3% versus 30.8%, p = 0.014), and revision rates (10.6% versus 26.9%, p < 0.001).

CONCLUSIONS

Treating PHF using a patient-specific, evidence-based algorithm restored preinjury quality of life as measured with the EQ-5D and approximately 90% normal shoulders as measured with the relative CS and the SSV. Adherence to the treatment algorithm was associated with significantly better clinical outcomes and substantially reduced complication and revision rates.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Late screw-related complications in locking plating of proximal humerus fractures: A systematic review

Locking plating is a common surgical treatment of proximal humeral fractures with satisfactory clinical results. Implant-related complications, especially screw-related, have been reported, however, the lack of information regarding their onset, used surgical technique, complexity of the fracture, bone quality etc., prevents from understanding the causes for them. The aim of this systematic review is to identify the potential risk factors for late screw complications by gathering information about the patient characteristics, comorbidities, fracture types, surgical approaches and implant types. A PubMed search was performed using humerus, fractures, bone and locking as keywords in clinical papers written in English. All abstracts and manuscripts on distal or humerus shaft fractures, and those on proximal humerus fractures without any or with only iatrogenic complications were excluded. One hundred studies met the inclusion criteria, resulting in 33% of the reported cases having at least one complication, with 11% of all complications being screw-related. Most of the latter were secondary screw perforations and screw cut-outs, being predominantly linked to poor bone quality, while screw loosening and retraction were found less frequently as a result of locking mechanism failure. Overall, the amount of information for complications was limited and screw perforation was the most frequent screw-related complication, mostly reported in female patients older than 50 years, following four-part or AO/OTA type C fractures and detected four weeks postoperatively. The sparse information in the literature could be an indicator that the late screw complications might have been under-reported and under-described, making the understanding of the screw-related complications even more challenging.

Evidence-based algorithm to treat patients with proximal humerus fractures-a prospective study with early clinical and overall performance results

BACKGROUND

On the basis of patients' demands, bone quality, and fracture type, we developed an evidence-based treatment algorithm for proximal humerus fractures (PHF) that includes all treatment modalities from open reduction and internal fixation, hemiprosthesis, to reverse total shoulder arthroplasty. This study was done to assess its feasibility and early clinical outcome.

MATERIALS AND METHODS

Patients with isolated PHF in 2014 and 2015 were included in this prospective study. The quality of life (EQ-5D) and the level of autonomy before injury were recorded. The fractures were classified and local bone quality was measured. When possible, patients were treated according to the algorithm. Radiographic and clinical follow-up-Constant score, subjective shoulder value, and EQ-5D-took place after 3 months and 1 year. The rate of unplanned surgery was analyzed.

RESULTS

A total of 192 patients (mean age 66 years; 58 male, 134 female) were included. Of these, 160 (83%) were treated according to the algorithm. In total, 132 patients were treated conservatively, 36 with open reduction and internal fixation and 24 with reverse total shoulder arthroplasty or hemiarthroplasty. Generally, the mean EQ-5D before trauma and 1 year after treatment was equal to 0.88 to 0.9 points. After 1 year, the overall mean relative Constant score was 95% and mean subjective shoulder value 84%. Unplanned surgery was necessary in 21 patients.

CONCLUSION

This comprehensive algorithm is designed as a noncompulsory treatment guideline for PHF, which prioritize the patient's demands and biology. The high adherence proves that it is a helpful tool for decision making. Furthermore, this algorithm leads to very satisfying overall results with low complication and revision rates.

Does an early mobilization and immediate home-based self-therapy exercise program displace proximal humeral fractures in conservative treatment? Observational study

BACKGROUND

Nonoperative management of proximal humeral fractures (PHFs) is the most common treatment, but its functional outcome may improve with early mobilization. In frail osteoporotic patients, quick recovery of prefracture independency is mandatory. This study assessed fracture displacement in PHFs managed with conservative treatment after early mobilization and a home-based self-exercise program.

METHODS

We retrospectively analyzed the radiologic displacement of fracture fragments of PHFs treated conservatively with early mobilization and a home-based self-exercise program.

RESULTS

Included were 99 patients with 26 one-part, 32 two-part, 32 three-part, and 9 four-part PHFs managed conservatively, followed by early mobilization and a home-based self-exercise program. In the x-ray examinations, the head displaced from varus into valgus 55° ± 23° to 42° ± 22°, in the normal range of anatomic values. The medial hinge displaced from medial to the diaphysis (+1 ± 6 mm) to lateral to the head (-0.6 ± 6 mm). The greater tuberosity displaced cranially from -1 ± 7 mm to 2 ± 5 mm. The Constant score at the 1-year follow-up was 79.69 ± 16.3.

DISCUSSION AND CONCLUSIONS

The home-based self-exercise program for conservative treatment of PHFs displaces the head-diaphysis angle and the medial hinge toward anatomic reduction, but there is a risk of greater tuberosity cranial displacement. Functional results are fairly good, allowing frail patients to keep on with their independency and life style. Because a large number of patients might need further physiotherapy, the quality of the home-based self-exercises should be supervised.

Locking Cap Designs Improve Fatigue Properties of Polyaxial Screws in Upper Extremity Applications

OBJECTIVES

This study sought to examine fatigue characteristics of 2 polyaxial locking screw designs: locking cap (LC) and cross-threaded (CT). The goal was to compare LC and CT implants at 0, 10, and 15 degrees of angulation to determine the effect of locking mechanism on screw-plate interface failure. The hypothesis was that LC implants would have superior fatigue properties in comparison to CT designs and that increased angulation of the screw would have a negative impact on the fatigue life of CT implants, but would not have any effect on LC implants.

METHODS

A total of 72 screws were tested in 4 upper extremity implants. Implants were subjected to cyclic shear loads and subsequent ramp to failure. Performance characteristics were statistically compared using nonparametric statistical methods.

RESULTS

Fatigue testing demonstrated that LC designs were consistently able to sustain a significantly higher number of cyclic loads than CT designs. There were no significant differences in the number of cycles sustained by LC designs because of changes in screw angle, but CT implants exhibited decreases in screw stability with increasing angulation.

CONCLUSIONS

Likely because of the spherical screw head geometry, LC fatigue characteristics are not influenced by the orientation of the screw relative to the plate. Application of an LC in the operating room requires additional time, but provides significantly more robust fixation of the screw, especially at oblique angles to the plate and provides a more predictable and consistent biomechanical result.

Minimally invasive polyaxial locking plate osteosynthesis for 3-4 part proximal humeral fractures: our institutional experience

INTRODUCTION

The objectives of this study were to describe the surgical technique of fixation of 3-4 part proximal humeral fractures with polyaxial locking plates utilising a minimally invasive approach and to evaluate the accuracy of reduction and stability of fixation.

PATIENTS AND METHODS

We retrospectively reviewed 90 patients. Fractures were classified according to the Neer classification system. Different radiological parameters were measured to assess the quality of reduction and the stability of fixation. Complications and clinical outcomes were evaluated after one year of minimum follow up.

RESULTS

There were 76 women and 14 men, with a mean age of 67.4years ±13 (range, 29-85). There were 60 3-part and 30 4-part fractures. Frozen cancellous allograft was used in 30 cases (33.3%). All fractures progressed to union and at one year follow up, the mean Constant score was 79.6±12(range, 62-100). Mean forward flexion, abduction, external rotation and internal rotation were 155°, 148°, 39° and vertebra Dorsal 8, respectively. Complications were noted in seven patients while the postoperative "head-diaphysis angle", "greater tuberosity height" and "medial metaphysis reconstruction" were close to the anatomical parameters; no significant differences were noted at one year radiological follow up.

CONCLUSION

Reliable and stable fixation can be expected with the use of polyaxial locking plate through a minimally invasive approach for the treatment of 3-4 part proximal humeral fractures. Satisfactory functional results for this procedure can be obtained.

Effects of ligation of lateral intermuscular septum perforating vessels on blood supply to the femur

INTRODUCTION

With a subvastus approach to the femur, the vessels that perforate the lateral intermuscular septum (LISP-vessels) must be ligated. The effect on the blood supply to the femur remains unclear. The purpose of the current study was to investigate the effect of ligation of the LISP-Vessels on the blood supply and to examine the anatomy of the LISP-vessels and the anastomoses around the femur.

MATERIALS

In six human cadavers the LISP vessels were ligated by a lateral subvastus approach on one side. The contralateral side served as control group. After bilateral injection of different coloured silicon dyes into the lateral and medial circumflex femoral artery (green), deep femoral artery (red) and the superficial femoral artery (blue) dissection was performed bilaterally. The arterial perfusion on both sides was compared and the anatomy of the LISP vessels studied.

RESULTS

The medullary perfusion of the femur was not altered by the ligation of the LISP vessels. It did also not lead to a decrease in periosteal vessel filling. The LISP vessels were shown to be a part of a complex and rich anastomotic network and play an important role in the perfusion of the femur and quadriceps muscle group. The ligature could be compensated for by this anastomotic network. Branches to the periosteum separate from the LISP vessels immediately after perforating the lateral intermuscular septum. The linea aspera turned out to be an important area for the femoral blood supply.

DISCUSSION AND CONCLUSIONS

Exposure of the femur through a lateral subvastus approach with ligation of LISP vessels causes a certain degree of soft tissue trauma. However, by using a gentle surgical technique the periostal perfusion of the femur can be preserved by a potent anastomotic network after ligation of the LISP vessels if they are not ligated to close to the lateral intermuscular septum and the linea aspera is not unnecessarily exposed.

Mid-term results of a less-invasive locking plate fixation method for proximal humeral fractures: a prospective observational study

Background

The optimal treatment for proximal humeral fractures remains under debate. In this article, we report the mid-term results of patients who underwent the less-invasive implantation of a polyaxial locking plate for displaced proximal humeral fractures.

Methods

This study included patients who were treated with a polyaxial locking plate via an anterolateral deltoid split approach from May 2008 to December 2011. We evaluated outcome parameters after a minimum follow-up period of 2.5 years (median 4.5 years, follow-up rate 62 %) including the age- and gender-dependent Constant score, the activities of daily living score, and the visual analog scale for both pain and subjective shoulder function.

Results

Of the 140 patients who underwent surgery, 114 were included in the follow-up and 71 completed the questionnaire. Fifteen patients (21 %) exhibited 2-fragment fractures, and 56 patients (79 %) exhibited 3- and 4-part fractures. The Constant score improved significantly (4.5 years: 70 ± 21, p < 0.001) between the first two follow-ups (6 weeks: 35 ± 14, 6 months: 56 ± 18, p < 0.001), and also between 6 months and 4.5 years post-surgery. At the final follow-up, the activities of daily living score had not reached pre-fracture levels (before trauma: 27 ± 5, 4.5 years: 20 ± 8, p < 0.001). A multivariate analysis showed that age has a more significant influence on the final outcome than fracture morphology or gender.

Conclusion

Although the less-invasive surgical procedure is a feasible treatment option in proximal humeral fractures with acceptable complications and considerable improvement during the first six months, a lengthy recovery time is required. The majority of our patients did not become pain-free or reach pre-fracture activity levels.

Minimally invasive plate osteosynthesis with a locking compression plate is superior to open reduction and internal fixation in the management of the proximal humerus fractures

BACKGROUND

The use of minimally invasive plate osteosynthesis (MIPO) via anterolateral deltoid splitting has good outcomes in the management of proximal humerus fractures. While using this approach has several advantages, including minimal soft tissue disruption, preservation of natural biology and minimal blood loss, there is an increased risk for axillary nerve damage. This study compared the advantages and clinical and radiological outcomes of MIPO or open reduction and internal fixation (ORIF) in patients with proximal humerus fractures.

METHODS

A matched-pair analysis was performed, and patient groups were matched according to age (±3 years), sex and fracture type. Forty-three pairs of patients (average age: MIPO, 63 and ORIF, 61) with a minimum follow-up of 12 months were enrolled in the study group. The patients were investigated radiographically and clinically using the Constant score.

RESULTS

The MIPO technique required less surgery time and caused less blood loss compared to ORIF (p < 0.01). In addition, MIPO required a smaller incision, resulted in less scarring, and was cosmetically more appealing and acceptable to female patients than ORIF. Following MIPO, patients had better functional results at 3 and 6 months, with better outcomes, less pain, higher satisfaction in activities of daily living, and a higher range of motion when compared to ORIF (p < 0.05). Fracture configuration, according to the AO/ASIF(Association for the Study of Internal Fixation) fracture classification, did not significantly influence the functional results. The complication rate was comparable between both groups.

CONCLUSION

The use of MIPO with a locking compression plate in the management of proximal humerus fractures is a safe and superior option compared to ORIF.

Mechanical effects of off-axis insertion of locking screws: should we do it?

OBJECTIVES

The purposes of this study were to evaluate the cantilevered bending strength and failure modes of locking screws inserted at various angles in a plate with fully circumferential threaded holes. As an additional measure, the amount of screw head prominence at these angles was also assessed.

METHODS

Standard 3.5-mm locking screws were inserted into round fully circumferential threaded holes through a standard straight 3.5-mm locking plate at various angles. The achieved angle of insertion and its prominence protruding from the far-bone side of the plate was measured using an optical luminescence technique. Each screw was then loaded at a constant rate until failure in a cantilevered bending scenario. The maximum cantilevered bending strength was measured, and the moment at failure was calculated.

RESULTS

There was a positive correlation between increasing insertion angle and increasing prominence; a higher screw insertion angle yielded greater prominence. Prominence values ranged from negligible to 2 mm. As screw insertion angle increased, the bending moment at failure decreased. Screws inserted to 3 degrees or below primarily failed through screw deformation at the minor diameter below the head, whereas screws inserted to greater than 3 degrees primarily failed through locking mechanism disengagement.

CONCLUSIONS

These findings indicate that cross threading may not be biomechanically advantageous and may change screw mode of failure. Based on these findings, screws inserted to 3 degrees or higher would reduce the bending moment at failure to approximately 50% of an orthogonally inserted screw.

The position and number of screws influence screw perforation of the humeral head in modern locking plates: a cadaver study

OBJECTIVES

Screw perforation of the humeral head in locking plate osteosynthesis occurs in up to 30% of cases. The current study compared different fixation possibilities (eg, number and position of screws) to reduce screw perforation in the humeral head.

METHODS

A humeral head fracture with a missing medial support was created in 30 fresh-frozen cadavers and fixed with a polyaxial locking plate (NCB PH; Zimmer, Warsaw, IN). The constructs were loaded with increasing force and the number of cycles until screw perforation was recorded. Four different fixation methods were tested: group 1 five screws with fixed angle, group 2 five screws in polyaxial position according to bone strength, group 3 three screws, and group 4 five screws with 1 as an inferomedial support screw.

RESULTS

More screws in the humeral head significantly increased the number of cycles before screw perforation. An inferomedial support screw further increased the number of cycles. Polyaxial screw placement compared with fixed-angle placement had no effect on the screw perforation phenomenon.

CONCLUSIONS

We recommend to position an inferomedial support screw, and at least 5 screws in the head fragment, when using a locking plate in proximal humerus fractures with disrupted medial hinge.

Clinical outcome and complications using a polyaxial locking plate in the treatment of displaced proximal humerus fractures. A reliable system?

INTRODUCTION

The surgical treatment of displaced proximal humeral fractures (ORIF) is a perpetual challenge to the surgeon. For this reason, the principle of polyaxiality was developed to provide an improved primary stability of the fracture through better anchorage of the screws, especially in osteoporotic bone. The aim of this study was to present clinical results with the polyaxial locking plate in the operative treatment of proximal humerus fractures in order to determine whether the technique of polyaxiality leads to better functional outcome and lower complication rates in comparison to monoaxial plates in the literature.

PATIENTS AND METHODS

Seventy-three patients with displaced proximal humeral fractures were treated surgically with the polyaxial locking Suture Plate™ (Arthrex(®)) between 03/2007 and 06/2009. Fifty-two of the patients (mean age, 69.9 ± 12.1) were included in a radiographical and clinical examination using the Constant score (CS) and the Disabilities of the Arm, Shoulder and Hand score (DASH).

RESULTS

The follow-up examinations were on average 13.9 ± 4.5 months (10-27 months) after surgical treatment. The mean CS of the patients was 66.0 ± 13.7 points, the age- and gender-related CS was 90.9% ± 20.0% and the mean DASH score was 23.8 ± 19.8 points for the injured side. The patients with a nearly anatomical reduction of their fracture (n = 13) reached a significantly higher CS (75.1 ± 8.5; p = 0.004) and DASH-score (13.6 ± 11.6; p = 0.043) and none of these patients had a complication. The complications were identified in 12 (23.1%) cases, 5 of which involved loss of reduction. All of these 5 cases were lacking of initial medial column support and 4 of which were type C2.3 AO-Classification.

CONCLUSION

The data show that the combination of angular stability with the possibility of variable polyaxial screw direction is a good concept for reduction and fixation of displaced proximal humeral fractures, but anatomical reduction and medial support remain important preconditions for a good outcome. However, a significantly lower rate of complications or better clinical outcome than that reported in the literature could not be found.

Predicting failure after surgical fixation of proximal humerus fractures

BACKGROUND

Several studies reported high failures rates after internal fixation of proximal humerus fractures. Loss of reduction and screw cut-out are the most common reasons for revision surgery. Several risk factors for failure have been described in the literature. The aim of the present study was to assess risk factors for failure after surgical fixation of unstable proximal humerus fractures in a multivariate setup.

METHODS

Two different surgical techniques (PHILOS locking plate and Humerusblock) were used. In the PHILOS group, every kind of postoperative relative movement between the implant and the humeral head or shaft was defined as failure. In the Humerusblock group, postoperative movement between the humeral head and the shaft in terms of angulation or translational displacement was defined as failure. The following parameters were assessed: age, gender, cancellous bone mineral density (BMD) of the humeral head, fracture type, medial metaphyseal comminution, medial metaphyseal head extension, initial angulation of the humeral head in the frontal plane, initial anteversion of the humeral head, medial hinge displacement, maximum displacement of the tuberosities with respect to the head, surgical technique, anatomic reconstruction and restoration of the medial cortical support.

RESULTS

The following parameters were found to have a significant influence on the failure rate: age, local BMD, anatomic reduction, and restoration of the medial cortical support. The failure rate significantly increased with the number of risk factors.

CONCLUSION

Preoperative assessment of the local BMD and the patients' biological age as well as intraoperative anatomic reduction and restoration of the medial cortical support are the essentials for successful surgical fixation of proximal humerus fractures. Multifragmentary fracture patterns in old patients with low local BMD are prone for fixation failure. If the surgeon is not able to achieve anatomic reduction and restoration of the medial cortical support intraoperatively in this situation, adjustments such as augmentation or primary arthroplasty should be considered.

Locking plate osteosynthesis in displaced 4-part fractures of the proximal humerus

BACKGROUND AND PURPOSE

There is considerable uncertainty about the optimal treatment of displaced 4-part fractures of the proximal humerus. Within the last decade, locking plate technology has been considered a breakthrough in the treatment of these complex injuries.

METHODS

We systematically identified and reviewed clinical studies on the benefits and harms after osteosynthesis with locking plates in displaced 4-part fractures.

RESULTS

We included 14 studies with 374 four-part fractures. There were 10 case series, 3 retrospective observational comparative studies, 1 prospective observational comparative study, and no randomized trials. Small studies with a high risk of bias precluded reliable estimates of functional outcome. High rates of complications (16-64%) and reoperations (11-27%) were reported.

INTERPRETATION

The empirical foundation for the value of locking plates in displaced 4-part fractures of the proximal humerus is weak. We emphasize the need for well-conducted randomized trials and observational studies.

Monoaxial versus polyaxial locking systems: a biomechanical analysis of different locking systems for the fixation of proximal humeral fractures

OBJECTIVE

The development of locking plate systems has led to polyaxial screws and new plate designs. This study compares monoaxial head locking screws (PHILOS© by Synthes) and a new generation of polyaxial locking screws (NCB-LE© by Zimmer) with respect to biomechanical stability.

METHODS

On nine pairs of randomised formalin fixed humerus specimens, standardised osteotomies and osteosyntheses with nine monoaxial (group A) und nine polyaxial (group B) plate/screw systems were performed. A material testing machine by Instron (M-10 14961-DE) was used for cyclic stress tests and crash tests until defined breakup criteria as endpoints were reached.

RESULTS

After axial cyclic stress 200 times at 90 N, plastic deformation was 1.02 mm in group A and 1.25 mm in group B. After the next cycle using 180 N the additional deformation averaged 0.23 mm in group A and 0.39 mm in group B. The deformation using 450 N was 0.72 mm in group A compared to 0.92 mm in group B. The final full power test resulted in a deformation average of 0.49 mm in group A and 0.63 mm in group B after 2,000 cycles using 450 N. When reaching the breakup criteria the plastic deformation of the NCB plate was 9.04 mm on average. The PHILOS plate was similarly deformed by 9.00 mm. As a result of the crash test, in group A the screws pulled out of the humeral head four times whereas the shaft broke one time and another time the implant was ripped out. The gap was closed four times. In group B, there were three cases of screw cut-through, four shaft fractures/screw avulsions from the shaft and two cases of gap closure.

CONCLUSION

The two systems resist the cyclic duration tests and the increasing force tests in a similar manner. The considerable clinical benefits of the polyaxial system are enhanced by equal biomechanical performance.

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

Locked plating attempts to improve mechanical stability via better anchorage of the screws in the bone. In 22 paired osteoporotic humeri an AO/ASIF 11-B 1 fracture was created. Locked and conventional plating using the same device of the latest generation was performed. Torsional loading around three axes (x = varus/valgus, y = flexion/extension, z = axial rotation) with an increasing moment (2, 3.5, 5 and 7.5 N·m) was applied. Interfragmentary motion within the locked group was lower for all three axes with higher cumulative survival rates (p < 0.05). The typical mode of failure was loss of fixation in the humeral head occurring earlier in the conventional group. The locking mechanism investigated provides more ultimate strength in an osteoporotic proximal humerus fracture model. Correlation with BMD suggests that this device may especially be suitable for use in osteoporotic bone.

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

Surgical treatment of most displaced proximal humerus fractures is challenging due to osteoporosis. Locking plates are intended to provide superior mechanical stability. In a prospective multicentre study 131 patients were treated with second generation locked plating (NCB-PH, Zimmer, Inc.). The open procedure (n = 78) was performed using a deltopectoral approach; the minimally invasive technique (n = 53) involved percutaneous reduction and an anterolateral deltoid split approach. Clinical and radiological follow-up was obtained. Improvement in function (ROM) was statistically significant. Fracture type (AO) had the most significant impact on the incidence of complications. The most frequent complications detected were intra-articular screw perforation (15%) and secondary displacement (8%). Complication rate and functional outcome of the NCB-PH are comparable to reports in the literature. Not all problems are likely to be solved by this new generation of implants, i.e. secondary dislocation still occurred in 8% of our patients.

Use of locking plates in the treatment of proximal humerus fractures

BACKGROUND/HYPOTHESIS

Open reduction and internal fixation (ORIF) using locked plating has demonstrated promise in the treatment of displaced proximal humerus fractures. The purpose of this article is to describe the surgical technique and to report early clinical results with this technique.

METHODS

Important surgical principles to follow include adequate use of locking screws in the humeral head, bone graft or bone graft substitutes when needed, rotator cuff sutures to assist with reduction and augment fixation, and sufficient use of intraoperative fluoroscopic imaging. A review was performed to evaluate early outcomes of ORIF with proximal humerus locking plates. All cases were fixed with the described surgical technique. Postoperative assessment included radiographic imaging, PENN/ASES Shoulder Scores, range-of-motion (ROM), and complications.

RESULTS

Fifty-two patients (54 shoulders) had minimum 6-month follow-up (13-month mean follow-up). Mean age was 65.5 years. Postoperatively, mean active forward elevation was 130.1 degrees, and mean active external rotation was 27.7 degrees. Mean post-op PENN shoulder score was 68.9 and mean post-op ASES score was 70.8. There were 11 (20.4%) complications in 10 (18.5%) shoulders after treatment with a proximal humerus locking plate. Three complications were classified as minor (5.6%), 8 as major (14.8%). Two shoulders (3.7%) required reoperation to address the complications.

CONCLUSION

The use of locking plates in the treatment of displaced proximal humerus fractures is becoming more widespread. With precise knowledge of and experience with the surgical technique, locked plating can be performed safely with good results. However, surgeons should be aware that complications can arise.