Locking plate fixation of humeral head fractures with a telescoping screw. A comparative biomechanical study versus a standard plate

ObjectivesLocking plate fixation of humeral head fractures bares the risk of glenohumeral screw penetration. In order to circumvent this problem it is recommended to insert shorter locking screws having at least a 6 mm distance to the humeral head cortex. This in turn may reduce fixation stability and may lead to early varus displacement. One second frequent failure mechanism is cranial displacement of the greater tubercle. The study evaluates the biomechanical properties of a locking plate employing an additional telescoping screw that may enhance resistance to varus displacement. Screw in screw fixation of the greater tubercle may reduce the rate of cranial displacement.MethodsIn four paired fresh-frozen human cadaver humeri (age > 70 years) a Neer IV/3 fracture was created with a 5 mm osteotomy gap simulating metaphyseal comminution. Limbs were randomly assigned to receive plate fixation with an additional telescoping screw (Humerus Tele Screw: HTS) and on the contralateral limb Philos plate fixation before biomechanical evaluation (MTS-Bionix 858.2). Standard locking screws were placed in both groups 6 mm below the radiological head circumference; the telescoping screw was placed in the subchondral layer. The greater tubercle was fixed with an additional screw in both techniques, in the HTS group the screw was anchored in the sleeve of the telescrew (screw in screw fixation).FindingsFixation stability with a mean stiffness of 300.9 ± 28.8 N/mm in the HTS plate group proved to be significantly higher than in the Philos plate group (184.2 ± 23.4 N/mm; p = 0.006). The HTS plate also resisted higher loads in terms of fixation failure with loss of reduction at 290 ± 58.6 N in comparison to 205 ± 8.6 N for the Philos plate (p = 0.2). Displacement of the greater tubercle occurred in no case of the HTS plate group and in two out of four cases in the Philos plate group.InterpretationThe HTS plate provides high fixation stability in an in vitro humeral head fracture model and securely prevents displacement of the greater tubercle.     

Dynamic hip screw with locking side plate: a viable treatment option for intertrochanteric fracture

Objective： Dynamic hip screw （DHS） is recommended for the fixation of stable intertrochanteric fractures. Its postoperative cut-out rate ranges from I% to 6%. In osteoporotic bone, normal screws in DHS blade provide less anchorage compared to locking screws. This study aims to compare DHS with locking side plate and conventional side plate. Methods： Fifty consecutive patients with intertrochanteric fractures were randomly allocated for fixation with a standard DHS （group A） and locking DHS （Combi plate, group B）. We compared the clinical and radiological outcomes for the conventional DHS and locking DHS in intertrochanteric fractures. Functional outcome was evaluated using the Parker mobility score. Results： Coxa valga was found more frequently in group A than in group B （12% vs. 0%, P=0.42）. Coxa vara showed the same trend （12% vs. 8%, P=0.81）. Rate of restoration of postoperative neck-shaft angle within 20° of sound side was higher in group B （8% cases） than in group A （4% cases, P=0.98）. The rate of anteversion angle restoration within 10° of sound side was also higher in group B （100% vs. 88%, P=0.85）. The average lag screw slippage in group A and group B was 3.2 mm and 4.2 mm, the average fracture union duration was 17.1 weeks and 16.4 weeks, and the mean Parker score was 5.6 and 5.8 respectively. Screw cut-out was seen in one patient in group A. No cut-out was seen in any of the patient in group B. No patient developed deep infection, avascular necrosis, deep vein thrombosis or any other significant complications. Conclusion： The present study demonstrated that treating intertrochanteric fracture with a locking DHS allows sound bone healing and is not associated with any major complications. Although this report is promising, it should be interpreted with caution because only a prospective study with a large sample size would allow definitive conclusion.     

Biomechanical analysis of locked and non-locked plate fixation of the clavicle

IntroductionDuring plate fixation of clavicular fractures the brachial plexus and subclavian vessels are vulnerable to injury beneath the clavicle. Locking plate fixation allows for mono-cortical fixation, theoretically reducing the risk of injury to these structures. Biomechanical analysis of the performance of such fixation is limited, and this study was designed to explore this further as a treatment option in clavicle fractures.Materials and methodsFixation of fifteen simulated mid-shaft fractures was undertaken using a combination of mono-cortical locked, bicortical locked and bicortical non-locked plating methods in cadaveric clavicles. Samples were then tested via three-point bending to destruction, and the performance of each with respect to failure load, bending stress, bending stiffness and Young's modulus was then analysed. The influence of the number of cortices engaged and locking was also assessed.ResultsClavicles fixed with monocortical locking plates displayed a significantly lower bending stress (12 ± 1 MPa) than both the bicortical locking (28 ± 3 MPa, p = 0.015) and non-locking specimens (24 ± 3 MPa, p = 0.002). Engaging two cortices with the fixation produced a significant increase in failure load (291 ± 28 N vs 138 ± 48 N, p = 0.018) and bending stress (26 ± 2 MPa vs 9.9 ± 3.5 MPa, p = 0.002) compared to single cortex fixation.DiscussionThe greatest influence upon the performance of the fixation was the number of cortices engaged, with bicortical fixation performing significantly better than mono-cortical. Whether or not the fixation device was a locking one did not have a significant bearing upon the performance.ConclusionThis in vitro biomechanical analysis demonstrates that mono-cortical locked plating fails at significantly lower levels of load and stress than bicortical locked and non-locked plating in mid-shaft fractures of the clavicle, and caution would therefore be advised in its use as a fixation modality for these injuries.     

Construct failure after open reduction and plate fixation of displaced midshaft clavicular fractures

IntroductionWorldwide, implants mostly used for fixation of displaced midshaft clavicular fractures (DMCF) are the easily to bend reconstruction plate and the stiffer small fragment locking compression plate. Construct failure rates after plate fixation of DMCF are reported around 5 percent. Possible risk factors for construct failure are implant type and fracture type. However, little is known about the influence of fracture fixation method on construct failure. The aim of this study was to assess construct failure in plate fixation of DMCF and to identify possible risk factors.MethodsAll consecutive patients treated in a level 1 trauma centre with open reduction and fixation of DMCF using a 3.5-mm reconstruction plate or 3.5-mm small fragment locking compression plate between 2007 and 2015 were evaluated. Potential risk factors for construct failure were analysed using univariate analysis.ResultsTwo hundred and fifty-nine patients were analysed. Fifty DMCF (19%) were fixated with a reconstruction plate and 209 (81%) with a small fragment locking compression plate. Construct failure was seen in 18 patients (6.9%), including 5 broken plates and 13 with screw loosening. Eight percent of all reconstruction plates broke in contrast to 0.5 percent of all small fragment locking compression plates (p = 0.001). All broken implants were used as a bridging plate. Loosening of screws was seen in older patients and when the plate was fixated with less than three bicortical screws on one side of the fracture (p = 0.002).ConclusionsOverall construct failure after open reduction and plate fixation of DMCF occurred in 6.9 percent. Risk factors for plate breakage were the use of a reconstruction plate and a bridging method for fracture fixation. Risk factors for screw loosening were an increasing patient age and plate fixation with less than three bicortical screws on one side of the fracture.RecommendationsBased on the results of this study our recommendation is to use a small fragment locking compression plate for open reduction and internal fixation of DMCF. The surgeon should always strive to fixate the plate on both sides of the fracture with at least three bicortical screws.     

Comparison of different locking plate fixation methods in lateral malleolus fractures

BackgroundSeveral fixation methods may be used for displaced lateral malleolar fractures. We aimed to compare clinical and radiologic outcomes associated with use of locking one third tubular plate vs. anatomical distal fibula locking plate in lateral malleolar fractures.MethodsA total of 62 orthopedic patients operated for lateral malleolus fracture were included in this retrospective study. Patients were divided into two groups regarding the plate used for fixation as locking one third tubular plate (group I; n = 37) and locking anatomical distal fibula plate (group II; n = 25). Data on Danis–Weber ankle fracture classification (Type A, Type B), duration of follow up, clinical outcome [ankle range of motion (ROM), American Orthopaedic Foot & Ankle Society (AOFAS) score], radiological outcomes (adequacy of reduction, loss of alignment), time to fracture healing and complications were recorded in study groups.ResultsNo significant difference was noted between groups in terms of AOFAS score [87.0 (73–100) vs. 85.0 (71–100), respectively (p = 0.339)] and no patients had severe restriction in sagittal and hindfoot motion in both groups. The two groups showed similar healing time [9.0 (7–13) weeks vs. 10.0 (8–13) weeks, respectively (p = 0.355)] and complication rate [0.0% vs. 4.0%, respectively (p = 0.403)].ConclusionsThis study revealed no significant difference between use of locking one third tubular plate and locking anatomical distal fibula plate in lateral malleolar fixation, in terms of clinical and radiological outcomes, complication rates and fracture healing time.     

Biomechanical cadaver testing of a fixed-angle plate in comparison to tension wiring and screw fixation in transverse patella fractures

IntroductionOperative treatment of patella fractures is frequently associated with implant failure and secondary dislocation which can be attributed to the employed hardware. Therefore, a 2.7 mm fixed-angle plate designed for the treatment of patella fractures was tested biomechanically against the currently preferred methods of fixation. It was hypothesized that under simulated cyclic loading fixed-angle plating would be superior to modified anterior tension wiring or cannulated lag screws with anterior tension wiring.Materials and methodsEighteen human cadaver knees, matched by bone mineral density and age, were divided into three groups of six. After setting a transverse patella fracture each group received one of the osteosyntheses mentioned above. Repetitive testing over 100 cycles was performed at non-destructive loads by simulating knee motion from 90° flexion to full extension.ResultsAnterior tension wiring as well as lag screws with tension wiring showed significant fracture displacement after the initial cycle already. Both constructs, lag screws plus wiring (3.7 ± 2.7 mm) as well as tension wiring alone (7.1 ± 2.2 mm) displayed fracture displacement of >2 mm which is clinically regarded as failure. Those patellae stabilized with fixed-angle plates showed no significant fracture gap widening after completion of 100 cycles (0.7 ± 0.5 mm). The differences between the fixed-angle plate group and the other two groups were statistically significant (p < 0.05).ConclusionIn contrast to modified anterior tension wiring and cannulated lag screws with anterior tension wiring the bilateral fixed-angle plate was the only fixation device to stabilize transverse patella fractures securely and sustainably.     

Calcar comminution as prognostic factor of clinical outcome after locking plate fixation of proximal humeral fractures

ObjectiveIn the treatment of proximal humeral fractures, the decision between open fixation and arthroplasty is often difficult. Applicable radiographic prognostic factors would be useful. The purpose of the present study was to investigate the influence of calcar comminution on the clinical and radiologic outcome after locking plate fixation of these fractures.MethodsIn patients with proximal humeral fractures that were treated by locking plate fixation, fracture morphology and the presence of comminution of the calcar were documented on preoperative radiographs. Follow-up for at least 2 years with radiologic assessment and functional outcome measurements including Constant score, subjective shoulder value (SSV), disabilities of the arm, shoulder and hand score (DASH), visual analogue scale (VAS) and short form (SF)-36 was performed.ResultsFollow-up examination (50.8 ± 20.6 months) was possible in 74 patients (46 female, 28 male, age 63.0 ± 15.9 years). Mean absolute Constant score (CS abs), CS adapted to age and gender (CS adap), DASH, SSV and VAS were 72.4 ± 14.5, 85.2 ± 17.3%, 15.7 ± 17.3, 80.3 ± 19.6% and 2.1 ± 2.2. Nonunion was present in 1.3%, cut-out in 5.4% and implant failure in 1.3%. Avascular necrosis (AVN) was seen in 12.2%, in three cases >24 months after the initial trauma. In the presence of calcar comminution, the clinical outcome (CS abs, CS adap, SSV and several parameters of SF-36) was significantly impaired, the odds ratio for these patients to have an absolute CS < 65 was 4.4 (95% confidence interval (CI): 1.4–13.7).ConclusionsThe treatment of proximal humeral fractures with locking plate fixation achieves good clinical mid-term results. Calcar comminution is a relevant and easy-to-detect prognostic factor for the functional and subjective outcome in these fractures.     

A double button adjustable loop device is biomechanically equivalent to tension band wire in the fixation of transverse patellar fractures—A cadaveric study

IntroductionTension-band wire fixation of patellar fractures is associated with significant hardware-related complications and infection. Braided polyester suture fixation is an alternative option. However, these suture fixations have higher failure rates due to the difficulty in achieving rigid suture knot fixation. The Arthrex syndesmotic TightRope, which is a double-button adjustable loop fixation device utilizing a 4-point locking system using FibreWire, may not only offer stiff rigid fixation using a knotless system, but may also obviate the need for implant removal due to hardware related problems. The aim of our study is to compare the fixation rigidity of patella fractures using Tightrope versus conventional tension-band wiring (TBW) in a cadaveric model.Materials and methodsTBW fixation was compared to TightRope fixation of transverse patella fractures in 5 matched pairs of cadaveric knees. The knees were cyclically brought through 0–90° of motion for a total of 500 cycles. Fracture gapping was measured before the start of the cycling, and at 50, 100, 200 and 500 cycles using an extensometer. The mean maximum fracture gapping was derived. Failure of the construct was defined as a displacement of more than 3 mm, patella fracture or implant breakage.ResultsAll but one knee from each group survived 500 cycles. The two failures were due to a fracture gap of more than 3 mm during cycling. There was no significant difference in the mean number of cycles tolerated. There was no implant breakage. There was no statistical significant difference in mean maximum fracture gap between the TBW and TightRope group at all cyclical milestones after 500 cycles (0.3026 ± 0.4091 mm vs 0.3558 ± 0.7173 mm, p = 0.388).ConclusionsWe found no difference between the TBW and Tightrope fixation in terms of fracture gapping and failure. With possible lower risk of complications such as implant migration and soft tissue irritation, we believe tightrope fixation is a feasible alternative in fracture management of transverse patella fractures.     

The effects of a displaced dorsal rim fracture on outcomes after volar plate fixation of a distal radius fracture

IntroductionThe purpose of this study was to determine whether a displaced dorsal rim fracture has an adverse effect on wrist function after volar plate fixation of a dorsally displaced distal radius fracture (DRF).Materials and methodsTwo matched cohorts of 23 matched patients, one with a displaced dorsal rim fracture >2 mm (group 1), and the other without a dorsal rim fracture (group 2) were analysed in this study of volar locking plate fixation for dorsally unstable DRFs. The two cohorts were analysed for differences in wrist function and wrist pain, radiographic parameters and arthritic grades of radiocarpal joints. Displacement of dorsal rim fragments and diameters of the retained articular portions of dorsal rims in group 1 were measured.ResultsNo significant difference was found between the two groups in overall wrist function or wrist pain. Mean displacement of dorsal rims in group 1 was 3.0 mm and the mean diameter of the retained articular portion of dorsal articular wall was 2.0 mm. No significant difference was found between the two groups in terms of any radiographic parameters or the arthritic grading of radiocarpal joints.ConclusionA displaced dorsal rim fracture does not appear to affect outcomes adversely after volar locking plate fixation of dorsally displaced DRFs.     

Biomechanical analysis of a novel femoral neck locking plate for treatment of vertical shear Pauwel's type C femoral neck fractures

BackgroundThe purpose of this study is to determine the biomechanical stability of a novel prototype femoral neck locking plate (FNLP) for treatment of Pauwels type C femoral neck fractures compared with other current fixation methods.MethodsForty femur sawbones were divided into groups and a vertical femoral neck fracture was made. Each group was repaired with one of the following: (CS) three parallel cancellous screws; (XCS) two cancellous lag screws into the head and one transverse lag screw into the calcar; and (FNLP) a novel FNLP with two 5.7 mm locking, one lag screw into the calcar and two screws into the shaft; and (AMBI) a two-hole, 135° AMBI plate with a derotation screw. All groups were tested for change in axial stiffness over 20 000 cycles, and rotational stiffness was measured before and after cyclic testing. A maximum load to failure test was also conducted. Results were compared with one-way analysis of variance (ANOVA) and Fisher protected least significant difference (PLSD).ResultsResults for axial stiffness show that AMBI, CS, XCS and FNLP are 2779.0, 2207.2, 3029.9 and 3210.7 N-m mm^?1, respectively. Rotational rigidity results are 4.5, 4.1, 17.1 and 18.7 N-m mm^?1. The average cyclic displacements were 0.75, 0.88, 0.80 and 0.65 mm, respectively. Destructive failure loads for AMBI, CS, XCS and FNLP were 2.3, 1.7, 1.6 and 1.9 kN, respectively.ConclusionsThe results of this experiment show statistically significant increases in axial stiffness for the FNLP compared with three traditional fixation methods. The FNLP demonstrates increased mechanical stiffness and combines the desirable features of current fixation methods.     

Biomechanical effect of the configuration of screw hole style on locking plate fixation in proximal humerus fracture with a simulated gap: A finite element analysis

BackgroundLocking plate fixation for proximal humeral fractures is a commonly used device. Recently, plate breakages were continuously reported that the implants all have a mixture of holes allowing placement of both locking and non-locking screws (so-called combi plates). In commercialized proximal humeral plates, there still are two screw hole styles included “locking and dynamic holes separated” and “locking hole only” configurations. It is important to understand the biomechanical effect of different screw hole style on the stress distribution in bone plate.MethodsFinite element method was employed to conduct a computational investigation. Three proximal humeral plate models with different screw hole configurations were reconstructed depended upon an identical commercialized implant. A three-dimensional model of a humerus was created using process of thresholding based on the grayscale values of the CT scanning of an intact humerus. A “virtual” subcapital osteotomy was performed. Simulations were performed under an increasing axial load. The von Mises stresses around the screw holes of the plate shaft, the construct stiffness and the directional displacement within the fracture gap were calculated for comparison.ResultsThe mean value of the peak von Mises stresses around the screw holes in the plate shaft was the highest for combi hole design while it was smallest for the locking and dynamic holes separated design. The stiffness of the plate-bone construct was 15% higher in the locking screw only design (132.6 N/mm) compared with the combi design (115.0 N/mm), and it was 4% higher than the combi design for the locking and dynamic holes separated design (119.5 N/mm). The displacement within the fracture gap was greatest in the combi hole design, whereas it was smallest for the locking hole only design.ConclusionsThe computed results provide a possible explanation for the breakages of combi plates revealed in clinical reports. The locking and dynamic holes separated design may be a better configuration to reduce the risk of plate fracture.     

Influence of plate material and screw design on stiffness and ultimate load of locked plating in osteoporotic proximal humeral fractures

IntroductionThe main purpose was to compare the biomechanical properties of a carbon-fibre reinforced polyetheretherketone (CF-PEEK) composite locking plate with pre-existing data of a titanium-alloy plate when used for fixation of an unstable 2-part fracture of the surgical neck of the humerus. The secondary purpose was to compare the mechanical behaviour of locking bolts and conventional locking cancellous screws.Methods7 pairs of fresh frozen human humeri were allocated to two equal groups. All specimens were fixed with the CF-PEEK plate. Cancellous screws (PEEK/screw) were compared to locking bolts (PEEK/bolt) for humeral head fixation. Stiffness, fracture gap deflection and ultimate load as well as load before screw perforation of the articular surface were assessed. Results were compared between groups and with pre-existing biomechanical data of a titanium-alloy plate.ResultsThe CF-PEEK plate featured significantly lower stiffness compared to the titanium-alloy plate (P < 0.001). In ultimate load testing, 6 out of 14 CF-PEEK plates failed due to irreversible deformation and cracking. No significant difference was observed between results of groups PEEK/screw and PEEK/bolt (P > 0.05).DiscussionThe CF-PEEK plate has more elastic properties and significantly increases movement at the fracture site of an unstable proximal humeral fracture model compared to the commonly used titanium-alloy plate. The screw design however does neither affect the constructs primary mechanical behaviour in the constellation tested nor the load before screw perforation.     

The biomechanical cost of variable angle locking screws

IntroductionVariable angle (VA) locking plates in fracture fixation surgery allow screws to be fastened to the plate within a conical “locus of vectors” in order to avoid existing prostheses, joint surfaces, or poor quality bone. Clinical failures of VA constructs in which screws have rotated at the plate/screw interface have been reported raising the concern that there may be a biomechanical cost for the increased flexibility that VA provides. The objective of this study was to test the mechanical properties of one commonly used VA locking mechanism with screws placed in both nominal and off–axis trajectories and compare these against the standard locking mechanism.MethodsVA locking screws were inserted into plates for distal femur fractures (VA Curved Condylar) at various angles (0° to 15° away from perpendicular). A control group of standard locking screws/plates was also tested. Maximum moment at the screw/plate interface and moment at two reference displacements were determined.ResultsVA screws locked perpendicular to the plate provided the greatest maximum moment and moment at the reference displacements when using the VA system, and demonstrated lower moments compared to standard locking screws/plates (p < 0.001). Based on linear regression, there was an average decrease of approximately 0.4 Nm screw-plate interface strength for every 1° increase in screw-plate angle (p < 0.001). Decreases (p<0.05) were discovered in both maximum moment and moment at the reference displacements for screws locked at 5° relative to those locked at 0°, 10° relative to 0°, and 15° relative to 10°.DiscussionStandard locking systems provided greater resistance to rotational failure at the screw/plate interface than variable angle locking systems. Variable angle systems provided the greatest resistance to rotation when the screw was inserted perpendicular to the plate. As the off-axis angle increased, the resistance to rotation at the screw/plate interface decreased almost linearly. It is unknown if these differences are clinically significant in an actual fracture construct, but recent reported failures in the distal femur suggest that they might be.ConclusionSurgeons should weigh the risks and benefits of VA systems and attempt to minimize the off-axis angle magnitude when VA systems are selected.     

The Association between Iliac Fixation and Proximal Stent-graft Migration during EVAR Follow-up: Mid-term Results of 154 Talent Devices

ObjectiveThis study investigated the importance of iliac fixation to secure endograft fixation.Materials and methodsComputed tomography (CT) scans of patients who underwent endovascular aneurysm repair with an endoprosthesis of great columnar strength (Talent? stent graft) were analysed retrospectively. Patients were enrolled consecutively between June 2000 and January 2007 and prospectively followed up with serial CT imaging. The superior mesenteric artery was used as a reference point to determine endograft migration (centerline endograft displacement of ≥10 mm). Proximal and distal fixation lengths were defined as the length of the endograft that was in full apposition to the aortic neck or common iliac arteries, respectively.ResultsProximal endograft migration occurred in 32 of 154 patients (21%) at a follow-up duration of 32 ± 14 months; 13 migrations required treatment (8%). Migration was more frequent in patients treated with aorto-uniiliac devices than bifurcation devices (p < 0.008). The migrator and non-migrator groups had similar demographic and abdominal aortic aneurysm (AAA) characteristics. The migrator group had significantly shorter proximal (30 ± 12 mm vs. 41 ± 13 mm, P < 0.001) and distal endograft fixation lengths (31 ± 18 mm vs. 47 ± 15 mm, P < 0.001). By multivariate regression analysis, proximal and distal endograft fixations were significant predictors for endograft migration at follow-up (P < 0.001).ConclusionIliac endograft fixation, along with proximal fixation, is a significant predictor for endograft migration.     

Working length and proximal screw constructs in plate osteosynthesis of distal femur fractures

BackgroundThe study purpose is to evaluate the working length, proximal screw density, and diaphyseal fixation mode and the correlation to fracture union after locking plate osteosynthesis of distal femoral fractures using bridge-plating technique.MethodsA four-year retrospective review was performed to identify patients undergoing operative fixation of distal femur fractures with a distal femoral locking plate using bridge-plating technique for the metadiaphyseal region. Primary variables included fracture union, secondary surgery for union, plate working length, and diaphyseal screw technique and configuration. Multiple secondary variables including plate metallurgy and coronal plane fracture alignment were also collected.ResultsNinety-six patients with distal femur fractures with a mean age 60 years met inclusion criteria. None of the clinical parameters were statistically significant indicators of union. Likewise, none of the following surgical technique parameters were associated with fracture union: plate metallurgy, the mean working length, screw density and number of proximal screws and screw cortices. However, diaphyseal screw technique did show statistical significance. Hybrid technique had a statistically significant higher chance of union when compared to locking (p = 0.02). All proximal locking screw constructs were 2.9 times more likely to lead to nonunion.ConclusionsPlating constructs with all locking screws used in the diaphysis when bridge-plating distal femur locking plates were 2.9 times more likely to incur a nonunion. However, other factors associated with more flexible fixation constructs such as increased working length, decreased proximal screw number, and decreased proximal screw density were not significantly associated with union in this study.     

Simple radiographic assessment of bone quality is associated with loss of surgical fixation in patients with proximal humeral fractures

AimThis study aimed to determine if the ratio of cortical thickness to shaft diameter of the humerus, as measured on a simple anterior-posterior shoulder radiograph, is associated with surgical fixation failure.Patients and Methods64 consecutive fractures in 63 patients (mean age 66.1years, range 35–90) operated with surgical fixation between March 2011 and July 2014 using PERI-LOC locking plate and screws (Smith and Nephew, UK) were identified. Predictors of bone quality were measured from preoperative radiographs, including ratio of the medial cortex to shaft diameter (medial cortical ratio, MCR). Loss of fixation (displacement, screw cut out, or change in neck-shaft angle >4 degrees) was determined on follow-up radiographs.ResultsLoss of fixation occurred in 14 patients (21.9%) during the follow up. Patients were older in the failure group 72.8 vs. 64.2 years (p = 0.007). The MCR was significantly lower in patients with failed fixation 0.170 vs 0.202, p = 0.019. Loss of fixation is three times more likely in patients with a MCR <0.16 (41% vs. 14%, p = 0.015). Increased fracture parts led to increased failure rate (p = 0.0005).ConclusionMedial cortex ratio is significantly associated with loss of surgical fixation and may prove to be a useful adjunct for clinical decision making in patients with proximal humeral fractures.     

Radiographic evaluation of first MTP joint arthrodesis for severe hallux valgus: Does the introduction of a lag screw improve union rates and correction of the intermetatarsal angle?

BackgroundFirst metatarsophalangeal (MTP-1) joint fusion is a reliable method for the correction of various deformities including hallux valgus and hallux rigidus. Ideal constructs provide high rates of fusion in desired alignment. The present study examines the union rates, as well as the change in dorsiflexion angle during the follow up period in patients who underwent MTP-1 fusion with a dorsal locking plate and a lag screw, versus patients fused with a dorsal locking plate alone.MethodsThis is a retrospective review of 99 feet undergoing MTP-1 fusion. Joints were fused using either a dorsal locking plate alone or a lag screw plus a dorsal locking plate. Union was determined radiographically during the follow up period. Suspected nonunions were confirmed with CT. Dorsiflexion angles were radiographically measured at first post-operative visit and at final follow up.ResultsThere were 36 patients in the lag screw plus dorsal plate group, and 63 in the dorsal plate group. Mean follow up was 12.9 months (Range: 12–33.5 months). The dorsal plate plus lag screw group had a significantly lower change in mean dorsiflexion angle (0.57° ± 5.01°) during the post-operative period compared to the dorsal plate group at final follow up versus the dorsal plate group (6.73° ± 7.07°).ConclusionThe addition of a lag screw to a dorsal locking plate for MTP-1 arthrodesis may offer improved stability of the joint in the sagittal plane over time compared to a dorsal plate alone.Level of evidenceRetrospective level III evidence.     

Surgical treatment of proximal humerus fractures using PHILOS plate

Objective：To evaluate functional outcome and complications of open reduction and internal fixation with proximal humeral internal locking system （PHILOS） plate for proximal humerus fractures.Methods：We reviewed 51 patients who underwent open reduction and internal fixation with PHILOS plate between the years 2007 to 2012.There were 35 men and 16 women with a mean age of 38 years （range 24-68）.There were 41 patients in the age group of ＜60 years and 10 patients in the age group of ＞60 years.According to Neer classification system,8,15 and 23 patients had 2-part,3-part,and 4-part fractures,respectively and 5 patients had 4-part fracture dislocation.All surgeries were carried out at our tertiary care trauma centre.Functional evaluation of the shoulder at final follow-up was done using Constant-Murley score.Results：The mean follow-up period was 30 months （range 12-44 months）.Two patients were lost to followup.Of the remaining 49 patients,all fractures were united clinically and radiologically.The mean time for radiological union was 12 weeks （range 8-20 weeks）.At the final follow-up the mean Constant-Murley score was 79 （range 50-100）.The results were excellent in 25 patients,good in 13 patients,fair in 6 patients and poor in 5 patients.During the follow-up,four cases of varus malunion,one case of subacromial impingement,one case of deep infection,one case of intraarticular screw penetration and one case of failure of fixation were noted.No cases of avascular necrosis,hardware failure,locking screw loosening or nonunion were noted.Conclusion：PHILOS provides stable fixation in proximal humerus fractures.To prevent potential complications like avascular necrosis,meticulous surgical dissection to preserve vascularity of humeral head is necessary.     

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

IntroductionProximal plate fixation in periprosthetic femur fractures can be improved by plate anchorage in the greater trochanter (lateral tension band principle) or bicortical locking screw placement beside the prosthesis stem in an embracement configuration. Both concepts were compared in a biomechanical test using a femoral hook plate (hook) or a locking attachment plate (LAP).MethodsAfter bone mineral density (BMD) measurement in the greater trochanter, six pairs of fresh frozen human femora were assigned to two groups and instrumented with cemented hip endoprostheses. A transverse osteotomy was set distal to the tip of the prosthesis, simulating a Vancouver B1 fracture. Each pair was instrumented using a plate tensioner with either hook or LAP construct. Cyclic testing (2 Hz) with physiologic profile and monotonically increasing load was performed until catastrophic failure. Plate stiffness was compared in a four-point-bending-test. Paired student’s-t-test was used for statistical evaluation (p < 0.05).ResultsMean BMD was 250 mgHA/ccm ± 47. The hook construct exhibited a significantly (p = 0.015) lower number of cycles and load to failure (26′177 cycles ± 2777; 3′118N ± 778) correlating significantly with BMD (R² = 0.83; p = 0.04) compared to the LAP construct (37′423 cycles ± 5′299; 4′242N ± 1′030) (R² = 0.71;p = 0.11). BMD was a significant covariate (p = 0.01). Plate stiffness was in a comparable range (hook Plate 468 N/mm ± 7; LCP 445 N/mm ± 6).ConclusionSubtrochanterically placed LAP provides an increased fixation strength under repetitive loading compared to hook plate fixation in the greater trochanter. Trochanteric fixation is highly BMD dependent and may be restricted to major greater trochanteric involvement requiring stabilization.     

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

IntroductionThe 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 methodsSeventy-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).ResultsThe 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.ConclusionThe 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.