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      The calcar screw in angular stable plate fixation of proximal humeral fractures - a case study

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          Abstract

          Background

          With new minimally-invasive approaches for angular stable plate fixation of proximal humeral fractures, the need for the placement of oblique inferomedial screws ('calcar screw') has increasingly been discussed. The purpose of this study was to investigate the influence of calcar screws on secondary loss of reduction and on the occurrence of complications.

          Methods

          Patients with a proximal humeral fracture who underwent angular stable plate fixation between 01/2007 and 07/2009 were included. On AP views of the shoulder, the difference in height between humeral head and the proximal end of the plate were determined postoperatively and at follow-up. Additionally, the occurrence of complications was documented. Patients with calcar screws were assigned to group C+, patients without to group C-.

          Results

          Follow-up was possible in 60 patients (C+ 6.7 ± 5.6 M/C- 5.0 ± 2.8 M). Humeral head necrosis occurred in 6 (C+, 15.4%) and 3 (C-, 14.3%) cases. Cut-out of the proximal screws was observed in 3 (C+, 7.7%) and 1 (C-, 4.8%) cases. In each group, 1 patient showed delayed union. Implant failure or lesions of the axillary nerve were not observed. In 44 patients, true AP and Neer views were available to measure the head-plate distance. There was a significant loss of reduction in group C- (2.56 ± 2.65 mm) compared to C+ (0.77 ± 1.44 mm; p = 0.01).

          Conclusions

          The placement of calcar screws in the angular stable plate fixation of proximal humeral fractures is associated with less secondary loss of reduction by providing inferomedial support. An increased risk for complications could not be shown.

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          Most cited references40

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          The importance of medial support in locked plating of proximal humerus fractures.

          The purpose of this study was to determine what factors influence the maintenance of fracture reduction after locked plating of proximal humerus fractures, and particularly the role of medial column support. University medical center. Thirty-five patients who underwent locked plating for a proximal humerus fracture were followed up until healing. For the initial and final radiographs, 2 lines were drawn perpendicular to the shaft of the plate, one at the top of the plate and one at the top of the humeral head, and the distance between them was measured as an indicator of loss of reduction. Medial support was considered to be present if the medial cortex was anatomically reduced, if the proximal fragment was impacted laterally in the distal shaft fragment, or if an oblique locking screw was positioned inferomedially in the proximal humeral head fragment. Multivariate linear regressions were performed to determine the effects that age, sex, fracture type, cement augmentation, and medial support had on loss of reduction. The presence of medial support had a significant effect on the magnitude of subsequent reduction loss (P < 0.001). Age, sex, fracture type, or cement augmentation had no effect on maintenance of reduction. Eighteen patients were determined to have adequate mechanical medial support (+MS group), and the remaining 17 patients did not have medial support (-MS group). In the +MS group, the average loss of humeral head height was 1.2 mm, and 1 case of articular screw penetration occurred that required removal. In the -MS group (without an appropriately placed inferomedial oblique screw and either nonanatomic humeral head malreduction with lateral displacement of the shaft or medial comminution), loss of humeral height averaged 5.8 mm (P < 0.001). There were 5 cases in this group in which screw penetration of the articular surface occurred (P = 0.02), 2 of which required reoperation for removal. All fractures in both groups healed without delay, and none required revision to arthroplasty. Achieving mechanical support of the inferomedial region of the proximal humerus seems to be important for maintaining fracture reduction. Locked plates in general do not appear to be a panacea for these fractures and are unable to support the humeral head alone from a lateral tension-band position. However, there are several factors that are in the surgeon's control that may improve the mechanical environment. Achieving an anatomic or slightly impacted stable reduction, as well as meticulously placing a superiorly directed oblique locked screw in the inferomedial region of the proximal fragment, may achieve more stable medial column support and allow for better maintenance of reduction.
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            Biomechanics of locked plates and screws.

            To review the biomechanical principles that guide fracture fixation with plates and screws; specifically to compare and contrast the function and roles of conventional unlocked plates to locked plates in fracture fixation. We review basic plate and screw function, discuss the design rationale for the new implants, and examine the biomechanical evidence that supports the use of such implants. Systematic review of the per reviewed English language orthopaedic literature listed on PubMed (National Library of Medicine online service). Papers selected for this review were drawn from peer review orthopaedic journals. All selected papers specifically discussed plate and screw biomechanics with regard to fracture fixation. PubMed search terms were: plates and screws, biomechanics, locked plates, PC-Fix, LISS, LCP, MIPO, and fracture fixation. The following topics are discussed: plate and screw function-neutralization plates and buttress plates, bridge plates; fracture stability-specifically how this effects gap strain and fracture union, conventional plate biomechanics, and locking plate biomechanics. Locked plates and conventional plates rely on completely different mechanical principles to provide fracture fixation and in so doing they provide different biological environments for healing. Locked plates may increasingly be indicated for indirect fracture reduction, diaphyseal/metaphyseal fractures in osteoporotic bone, bridging severely comminuted fractures, and the plating of fractures where anatomical constraints prevent plating on the tension side of the bone. Conventional plates may continue to be the fixation method of choice for periarticular fractures which demand perfect anatomical reduction and to certain types of nonunions which require increased stability for union.
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              Open reduction and internal fixation of proximal humerus fractures using a proximal humeral locked plate: a prospective multicenter analysis.

              The goal of this study is to evaluate the incidence of complications and the functional outcome after open reduction and internal fixation with the proximal humeral locking plate (Philos). Prospective case series. Multicenter study in 8 trauma units (levels I, II, and III) with recruitment between September 12, 2002, and January 9, 2005. One hundred fifty-seven patients with 158 fractures. Open reduction and internal fixation with a Philos plate. Occurrence of postoperative complications up to 1 year and active follow-up for 1 year with radiologic assessment to observe fracture healing, alignment, reduction, avascular necrosis, and functional outcome measurements including Constant, Disabilities of the Arm, Shoulder, and Hand, and Neer scores. One-year follow-up rate was 84%. The incidence of experiencing any implant-related complication was 9% and 35% for nonimplant-related complications. Primary screw perforation was the most frequent problem (14%) followed by secondary screw perforation (8%) and avascular necrosis (8%). After 1 year, a mean Constant score of 72 points (87% of the contralateral noninjured side), a mean Neer score of 76 points, and a mean Disabilities of the Arm, Shoulder, and Hand score of 16 points were achieved. Fixation with Philos plates preserves achieved reduction, and a good functional outcome can be expected. However, complication incidence proportions are high, particularly due to primary and secondary screw perforations into the glenohumeral joint, with an overall complication rate of 35%. More accurate length measurement and shorter screw selection should prevent primary screw perforation. Awareness of obtaining anatomic reduction of the tubercles and restoring the medial support should reduce the incidence of secondary screw perforations, even in osteopenic bone.
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                Author and article information

                Journal
                J Orthop Surg Res
                Journal of Orthopaedic Surgery and Research
                BioMed Central
                1749-799X
                2011
                24 September 2011
                : 6
                : 50
                Affiliations
                [1 ]Division of Trauma Surgery, University Hospital Zurich, Rämistrasse 100, 8091 Zurich, Switzerland
                Article
                1749-799X-6-50
                10.1186/1749-799X-6-50
                3189144
                21943090
                a9516065-37fa-48b6-888f-d25c1eb667db
                Copyright ©2011 Osterhoff et al; licensee BioMed Central Ltd.

                This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

                Categories
                Research Article

                Surgery
                fracture,locked screw,proximal humerus,locking plate
                Surgery
                fracture, locked screw, proximal humerus, locking plate

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