Reconstruction of Monteggia-like proximal ulna fractures using different fixation devices: A biomechanical study

BackgroundComminuted proximal ulna fractures are rare and reconstruction of these fractures is discussed controversially. The aim of this study was to test three currently available plate devices in a standardized comminuted four-part fracture model created in proximal ulna sawbones.Material and methodsA standardized four-part fracture of the proximal ulna was created in 80 sawbones. Reconstruction was performed by five experienced test surgeons according to a standardized reconstruction protocol. Each surgeon reconstructed 4 fractures with a 3.5 mm eight-hole reconstruction plate, 4 fractures with seven-hole third-tubular double plates and 4 fractures with a 3.5 mm anatomical seven-hole locked angle proximal ulna plate. 4 more fractures were reconstructed with simple K-wires as a reference construct for further experiments. Outcome measurements were time for reconstruction, quality of reconstruction and stability of the reconstruction. Stability testing was done in 90° and 30° flexion of the elbow. Testing in 30° flexion was done to test the anteroposterior stability regarding the fixed coronoid process.ResultsTime for reconstruction was significantly less for K-wire fixation than for the plate devices. Time for reconstruction plating and locked angle plating was significantly lower than for double plating (p < 0.005). Quality of reduction did not differ between the three plate systems (p < 0.05). K-wire fixation showed the best quality of reduction (p < 0.005). In 90° of elbow flexion the anatomic locked angle olecranon plate showed a significantly higher stability compared to the other devices. Furthermore the tubular double plating was significantly more stable than reconstruction plating or K-wire fixation (p < 0.05). In anteroposterior loading at 30°, the stability did not differ between the 4 different fixation techniques (p > 0.05). For all devices the testing in 30° flexion showed a significantly higher rigidity compared to 90° flexion.ConclusionThe locked angle plate system showed the highest stability in 90° of elbow flexion. Each implant was more stable in 30° flexion than in 90° flexion. Testing of the anterior stability of the elbow did not show any differences between the different implants. Because of the superior stability of this device, we conclude that locked angle plating should be preferred for reconstruction of monteggia like complex proximal ulna fractures.     

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.     

Biomechanical comparison of a lateral polyaxial locking plate with a posterolateral polyaxial locking plate applied to the distal fibula

BackgroundPolyaxial locking plates are becoming popular for the fixation of distal fibula fractures. This study establishes how construct stiffness and plate loosening, measured as range of motion, differs between lateral and posterolateral plate location.MethodsSeven matched pairs of cadaver fibulae were osteotomized in standardized fashion to produce a Weber type B distal fibula fracture. The fragments were fixated with an interfragmentary lag screw and polyaxial locking plates, with one fibula in each pair receiving a posterolateral anti-glide-plate, and the other a lateral neutralization-plate. In a biomechanical test, the bending and torsional stiffnesses of the constructs and the ranges of motion (ROM) were measured and subjected to a paired comparison.ResultsThe laterally plated group had a higher median (interquartile range) bending stiffness (29.2 (19.7) N/mm) and a smaller range of motion (2.06 (1.99) mm) than the posterolaterally plated group (14.6 (20.6) N/mm, and 4.11 (3.28) mm, respectively); however, the results were not statistically significant (p_bending = 0.314; p_ROM = 0.325). Similarly, the torsional stiffness did not differ significantly between the two groups (laterally plated: 426 (259) N mm/°; posterolaterally plated: 248 (399) N mm/°; p_torsion = 0.900). The range of motion measurements between the two groups under torsional loading were also statistically insignificant (laterally plated: 8.88 (6.30) mm; posterolaterally plated: 15.34 (12.64) mm; p_ROM = 0.900).ConclusionIn biomechanical cadaver-model tests of Weber type B fracture fixation with polyaxial locking plates, laterally plated constructs and posterolaterally plated constructs performed without significantly difference. Therefore, other considerations, such as access morbidity, associated injuries, patient anatomy, or surgeon's preference, may guide the choice of plating pattern. Further clinical studies will be needed for the establishment of definitive recommendations. Clinical relevance: Information on the behavior of polyaxial locking plates is relevant to surgeons performing internal fixation of distal fibula fractures.     

Biomechanical comparison of plate and screw fixation in anterior pelvic ring fractures with low bone mineral density

IntroductionOsteosynthesis of anterior pubic ramus fractures can be challenging, especially in poor bone quality. The aim of the present study was to compare plate and retrograde endomedullary screw fixation of the superior pubic ramus with low bone mineral density (BMD).Materials and methodsTwelve human cadaveric hemi-pelvises were analyzed in a matched pair study design. BMD of the specimens was 35 ± 30 mgHA/cm³, as measured in the fifth lumbar vertebra. A simulated two-fragment superior pubic ramus fracture model was fixed with either a 7.3-mm cannulated retrograde screw (Group 1) or a 10-hole 3.5-mm reconstruction plate (Group 2). Cyclic progressively increasing axial loading was applied through the acetabulum. Relative interfragmentary movements were captured using an optical motion tracking system.ResultsInitial axial construct stiffness was 424 ± 116.1 N/mm in Group 1 and 464 ± 69.7 N/mm in Group 2, with no significant difference (p = 0.345). Displacement and gap angle at the fracture site during cyclic loading were significantly higher in Group 1 compared to Group 2. Cycles to failure, based on clinically relevant criteria, were significantly lower in Group 1 (3469 ± 1837) compared to Group 2 (10,226 ± 3295) (p = 0.028). Failure mode in Group 1 was characterized by screw cutting through the cancellous bone. In Group 2 the specimens exclusively failed by plate bending.ConclusionsFrom biomechanical point of view, pubic ramus stabilization with plate osteosynthesis is superior compared to a single retrograde screw fixation in osteoporotic bone. However, the extensive surgical approach needed for plating must be considered.     

AO extra-articular distal humerus locking plate: extended spectrum of usage in intra-articular distal fractures with metaphyseal extension—our experience with 20 cases

Background

LCP extra-articular plate designed by AO has been used in extra-articular fractures of the distal humerus, mal-unions, and nonunions of the distal humerus. They provide anatomically shaped and angular stable fixation system for extra-articular fractures of the distal humerus. We extended the usage spectrum of this plate to the extra-articular with intra-articular distal humerus fractures and compared it with the standard orthogonal locking plate fixation.

Methods

We included 22 consecutive distal humerus intra-articular fractures with metaphyseal and diaphyseal extension into the study. Each case underwent osteosynthesis with LCP extra-articular plate fixation and augmented the intra-articular fragments with 4.0 mm partially threaded cancellous screws. The cost, surgical time, VAS, Modified Mayo Clinic Performance Index for elbow, and postoperative complications were recorded. The radiological union and postoperative elbow range of motion were assessed at 6 weeks, 6, and 12 months of follow-up. Twenty cases completed the scheduled follow-up. The results were compared with retrospective data of 20 cases from our institute where similar fractures were treated with standard orthogonal LCP distal humerus plate (LCPDHP).

Results

The radiological union rates and the range of motion at 6 weeks, 6, and 12 months in both the groups were comparable and did not vary significantly (p > 0.05). The cost and operative time with the LCP extra-articular plates were significantly less (p < 0.05) when compared to the group LCPDHP.

Conclusion

The usage spectrum of extra-articular distal humerus locking plate can be extended to intra-articular fractures. It provides good results and significantly reduces the cost and operative time.     

Anteroinferior 2.7-mm versus 3.5-mm plating of the clavicle: A biomechanical study

IntroductionLower patient satisfaction and high rates of plate prominence has led to the use of lower profile, smaller plates in the treatment of midshaft clavicle fractures. Specifically regarding the use of 2.7 mm reconstruction plates, there lacks biomechanical comparison to its more robust 3.5 mm counterpart. This study was designed to compare the mechanical properties of anteroinferior plate fixation on a clavicle fracture model using either 2.7 mm or 3.5 mm reconstruction plates.MethodsForty-eight synthetic left clavicles were divided into two groups based on the type of fixation: 3.5 mm or 2.7 mm pelvic reconstruction plate fixed in the anteroinferior position. Fixation was tested on AO/OTA 15B1.3 transverse midshaft fractures. Each specimen underwent the following three mechanical tests: axial compression, torsion, and four-point bending.ResultsSignificant differences were observed in axial (p = 0.016) and torsional (p = 0.00097) stiffness between the two groups. The average bending rigidity (EI) was found to be significantly lower for the 2.7-mm plates as compared to the 3.5-mm plates (p = 0.03). The loading scenarios performed in the mechanical tests did not lead to failure of any implants.ConclusionWhile our results show clear mechanical superiority of 3.5-mm reconstruction plates over 2.7-mm plates, superior results in the clinical setting may not necessarily translate. With exceptional mechanical strength also noted for the 2.7 mm plate, well above the biomechanical properties of an intact clavicle, these results may obviate the need for robust plates in general.     

The results of tension band rotator cuff suture fixation of locked plating of displaced proximal humerus fractures

IntroductionThe purpose of this study was to assess 1-year outcomes of patients with displaced proximal humerus fractures who underwent treatment with locked plate fixation with rotator cuff suture augmentation.MethodsA total of 86 patients who had sustained 2, 3 and 4-part displaced proximal humerus fractures underwent locked plate fixation with multiple sutures placed in the cuff tendons. Clinical outcome variables included active forward elevation (AFE), active external rotation (AER), and Constant and American Shoulder and Elbow Surgeons (ASES) scores. Post-operative variables included the following complications: varus re-collapse, loss of fixation, osteonecrosis of the humeral head (AVN), screw cut out, hardware failure and infection.ResultsForty-one patients were available with minimum of 1-year follow-up. Mean AFE was 142 ± 17.0° and AER was 41 ± 13.0°. The overall complication rate was 14.6%, with osteonecrosis being the most common (12.2%). Of the 21 patients (51.2%) that initially had varus displacement, all but one maintained anatomic reduction and fixation. Mean ASES score was 78.2 ± 20.0 and average Constant score was 72.7 ± 17.6. Bivariate analyses demonstrated that pre-operative medial comminution (p = 0.297) or varus collapse (p = 0.95) were not associated with an increased likelihood of sustaining a complication.ConclusionsFollow-up of patients in this series demonstrated a low overall complication rate and excellent functional outcomes. We believe suture augmentation of the rotator cuff can counteract varus forces on proximal humerus fractures fixed with locked plates, and should be performed routinely in displaced 2, 3 and 4 part fractures.     

Is there a benefit of proximal locking screws in osteoporotic distal radius fractures? – A biomechanical study

IntroductionThe distal radial fracture is a common fracture and frequently seen in geriatric patients. During the last years, volar plating has become a popular treatment option. While the application of locking screws at the distal fragment is widely accepted, there is no evidence for their use at the radial shaft.Materials and methodsIn six osteoporotic pairs of matched human cadaver radii an extra-articular model creating an AO 23-A2.1 fracture was employed. Osteosynthesis were performed using the APTUS 2.5 Adaptive TriLock Distal Radius System (Medartis AG) with locking (LS) or non-locking screws (NLS) for proximal fixation. Biomechanical testing was performed in a staircase fashion: starting with 50 cycles at 200 N, the load was continuously increased by 50 N every 80 cycles up to a maximum force of 400 N. Finally, load to failure was analyzed with failure defined as sudden loss of force measured (20%) or major deformation of the radii (10 mm).ResultsAt 200 N, 250 N, 300 N, 400 N and load to failure, the NLS group showed a higher degree of elastic modulus. In contrast, the LS group showed higher elastic modulus at 350 N. Maximum force was higher in the LS group without reaching statistical significance. Reasons for loss of fixation were longitudinal shaft fractures, horizontal peri-implant fractures and distal cutting out. No difference was seen between the two groups concerning the development of the above mentioned complications.ConclusionOur study did not show biomechanical superiority for distal radius fracture fixation by using locking screws in the proximal holes in an osteoporotic cadaver study. At load to failure, longitudinal shaft fractures and peri-implant fractures seemed to be a more relevant problem rather than failure of the proximal fixation.     

A biomechanical study comparing proximal femur nail and proximal femur locking compression plate in fixation of reverse oblique proximal femur fractures

BackgroundThe reverse oblique trochanteric fractures are common fractures and its treatment poses a challenge. The purpose of this study was to compare the biomechanical parameters of the construct using proximal femoral nail (PFN) and proximal femoral locking compression plates (PFLCP) in these fractures using cadaveric specimens.Materials and MethodsTwenty freshly harvested cadaveric femoral specimens were randomly assigned to two groups after measuring bone mineral density, ten of which were implanted with PFN and the other ten with PFLCP. The constructs were made unstable to simulate reverse oblique trochanteric fracture (AO type 31A3.3) by removing a standard size posteromedial wedge. These constructs were tested in a computer controlled cyclic compressive loading with 200 kg at a frequency of 1 cycle/s (1 Hz) and test was observed for 50,000 cycles or until implant failure, whichever occurred earlier. Peak displacements were measured and analysis was done to determine axial stiffness and subsidence in axial loading.ResultsAll the specimens in PFN group completed 50,000 cycles and in PFLCP group, seven specimens completed 50,000 cycles. Average subsidence in PFN group was 1.24 ± 0.22 mm and in PFLCP group was 1.48 ± 0.38 mm. The average stiffness of PFN group (72.6 ± 6.8 N/mm) was significantly higher than of PFLCP group (62.4 ± 4.9 N/mm) (P = 0.04). The average number of cycles sustained by PFLCP was 46634 and for PFN group was 50,000 (P = 0.06).ConclusionThe PFN is biomechanically superior to PFLCP in terms of axial stiffness, subsidence and number of specimens failed for the fixation of reverse oblique trochanteric fractures of femur.     

Biomechanical results of percutaneous calcaneal osteotomy using two different osteotomy designs

BackgroundPercutaneous osteotomy of calcaneus has been proposed to reduce the complication rate and became more and more popular. The bone cut can be performed as a straight or chevron-like (V) osteotomy using a Shannon burr. Comparative studies of straight or V-osteotomy as like as one or two screws in percutaneous calcaneal osteotomies are missing in the literature. We hypothesize that the V-osteotomy will result in a higher stiffness in biomechanical testing as the straight osteotomy using single screw for fixation.MethodsThe straight osteotomy (9 fresh–frozen specimens) and V-osteotomy (9 fresh–frozen specimens) was performed and the calcaneal tuberosity was moved 10 mm medially and slightly rotated. One 6,5 mm cancellous compression screw was used for osteosynthesis. Specimens were preconditioned with 100 N over 100 cycles. The force was increased after every 100 N by 100 N from 200 to 500 N. This was followed by cyclic loading with 600 N for 500 cycles.ResultsDespite the higher mean values of the group with V-osteotomy, no significant difference was registered between the two groups regarding the stiffness at all force levels. A higher failure rate was observed in the group with straight osteotomy.ConclusionThe moderate correlation of bone density and stiffness in the V-group, and significantly lower failure rate with no secondary dislocation in fluoroscopy indicates the superiority of the V-osteotomy in the present study. Whether the demonstrated advantages can be reflected in clinical practice should be investigated in further studies.Level of clinical evidence: 5     

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.     

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.     

Primary stability and stiffness in ankle arthrodes—Crossed screws versus anterior plating

BackgroundAnkle arthrodesis is commonly used for the treatment of osteoarthritis or failed arthroplasty. Screw fixation is the predominant technique to perform ankle arthrodesis. Due to a considerable frequency of failures research suggests the use of an anatomically shaped anterior double plate system as a reliable method for isolated tibiotalar arthrodesis. The purpose of the present biomechanical study was to compare two groups of ankle fusion constructs – three screw fixation and an anterior double plate system – in terms of primary stability and stiffness.MethodsSix matched-pairs human cadaveric lower legs (Thiel fixated) were used in this study. One specimen from each pair was randomly assigned to be stabilized with the anterior double plate system and the other with the three-screw technique. The different arthrodesis methods were tested by dorsiflexing the foot until failure of the system, defined as rotation of the talus relative to the tibia in the sagittal plane. Experiments were performed on a universal materials testing machine. The force required to make arthrodesis fail was documented. For calculation of the stiffness, a linear regression was fitted to the force–displacement curve in the linear portion of the curve and its slope taken as the stiffness.ResultsFor the anatomically shaped double-plate system a mean load of 967 N was needed (range from 570 N to 1400 N) to make arthrodesis fail. The three-screw fixation method resisted a mean load of 190 N (range from 100 N to 280 N) (p = 0.005). In terms of stiffness a mean of 56 N/mm (range from 35 N/mm to 79 N/mm) was achieved for the anatomically shaped double-plate system whereas a mean of 10 N/mm (range from 6 N/mm to 18 N/mm) was achieved for the three-screw fixation method (p = 0.004).ConclusionsOur biomechanical data demonstrates that the anterior double-plate system is significantly superior to the three-screw fixation technique for ankle arthrodesis in terms of primary stability and stiffness.     

Posterior buttress plate with locking compression plate for Hoffa fracture

BackgroundMany difficulties are associated with treating fractures of the posterior condyle of the femur (Hoffa fractures). Anatomical reduction and internal fixation are optimum for such intra-articular fractures. Some surgeons use anteroposterior screws to achieve direct stability. However, screw fixation is not adequate in some cases. To increase stability, we treat Hoffa fractures with a posterior buttress plate; we use a twisted, 1/3 tubular plate at the posterior surface and a supplementary, locking compression plate (LCP) for additional stability.MethodsPatients who had sustained Hoffa fractures between January 2006 and March 2009 were included in this study. Patients comprised three males and two females with a mean age of 73.6 years at the time of surgery. A 3.5-mm 1/3 tubular plate was twisted and applied to the posterolateral aspect of the distal femur. This was combined with an LCP on the distal femur to achieve a rafting effect.ResultsAll fractures were healed within 15 weeks. There were no instances of nonunion, infection, or implant removal. The mean range of motion was ?3° to 121°. Four patients had no pain in the treated limb and one had mild pain on weight bearing. The average Oxford Knee Score was 44.6 points. All patients achieved satisfactory joint function and regained their walking ability with good clinical results.ConclusionsImproved stability associated with this technique enables patients to begin range-of-motion training and return to their normal activities sooner; this resulted in good outcome.     

Impact of cement-augmented condylar screws in locking plate osteosynthesis for distal femoral fractures — A biomechanical analysis

IntroductionCompromised bone quality and the need for early mobilization continue to lead to implant failure in elderly patients with distal femoral fractures. The cement augmentation of screws might facilitate improving implant anchorage. The aim of this study was to analyse the impact of cement augmentation of the condylar screws on implant fixation in a human cadaveric bone model.Material and methodsTen pairs of osteoporotic femora (mean age: 90 years, range: 84–99 years) were used. A 2-cm gap osteotomy was created in the metaphyseal region to simulate an unstable AO/OTA 33-A3 fracture. All specimens were treated with a polyaxial locking plate. Specimens randomly assigned to the augmented group received an additional cement augmentation of the condylar screws using bone cement. A servohydraulic testing machine was used to perform incremental cyclic axial loading using a load-to-failure mode.ResultsAll specimens survived at least 800 N of axial compressive force. The mean compressive forces leading to failure were 1620 N (95% CI: 1382–1858 N) in the non-augmented group and 2420 N (95% CI: 2054–2786 N) in the group with cement-augmented condylar screws (p = 0.005).Deformation with cutting out of the condylar screws and condylar fracture were the most common reasons for failure in both groups. Whereas axial stiffness was comparable between both osteosyntheses (p = 0.508), significant differences were observed for the plastic deformation of the constructs (p = 0.014).ConclusionThe results of the present study showed that the cement augmentation of the condylar screws might be a promising technique for the fixation of distal femoral fractures in elderly patients with osteoporotic bones.     

Orthogonal plating of intra-articular distal radius fractures with an associated radial column fracture via a single volar approach

IntroductionThe purpose of this study was to investigate the radiographic and functional outcome of orthogonal plating (two plates at right angles) via a single volar approach for fixation of intra-articular distal radius fractures with an associated radial column fracture.MethodsIn a retrospective, chart-based review, we identified 14 consecutive patients with an intra-articular distal radial fracture who had been treated with locked volar plate fixation and an additional radial column plate. Radial column plates were LCP Distal Radius Plates 2.4; volar plates were LCP Distal Radius Plates 2.4 (n = 13) or LCP T-plate (n = 1). These patients were operated on using the extended volar flexor carpi radialis (FCR) approach as described by Orbay. Radiographic measurements, healing rates, time to union, complications, range of motion, the Gartland and Werley score, and the QuickDASH questionnaire were done in order to evaluate the radiographic and functional outcomes of this technique.ResultsThirteen of the 14 fractures healed within 7 weeks after surgery. Two implant removals were done. One patient had malposition of the fracture and carpal tunnel symptoms, which required a second surgery. No other complications (e.g., first dorsal compartment problems, radial plate prominence problems and radial sensory nerve problems) were observed. The average length of follow-up was 30 months (range, 12.8 months to 5.4 years). Radiographic results after healing were radial inclination 20°, radial length 11.4 mm, tilt 6° volar, ulnar variance ?0.5 mm, articular gap 0.1 mm and step-off 0.1 mm. Wrist range of motion was flexion–extension arc 93°, ulnar–radial deviation arc 49° and pronation–supination arc 152°. Nine patients scored ‘excellent’ on the Gartland and Werley score, while the remaining five patients scored ‘good’. The average QuickDASH score was 13.4.ConclusionAdditional fixation of a radial column process in an intra-articular distal radius fracture via the extended FCR approach using a standard volar plate and radial LCP resulted in good/excellent radiographic and functional outcome.Level of evidenceTherapeutic IV.     

Finite element analysis of the three different posterior malleolus fixation strategies in relation to different fracture sizes

PurposeAppropriate fixation method for the posterior malleolar fractures (PMF) according to the fracture size is still not clear. Aim of this study was to evaluate the outcomes of the different fixation methods used for fixation of PMF by finite element analysis (FEA) and to compare the effect of fixation constructs on the size of the fracture computationally.Materials and methodsThree dimensional model of the tibia was reconstructed from computed tomography (CT) images. PMF of 30%, 40% and 50% fragment sizes were simulated through computational processing. Two antero-posterior (AP) lag screws, two postero-anterior (PA) lag screws and posterior buttress plate were analysed for three different fracture volumes. The simulated loads of 350 N and 700 N were applied to the proximal tibial end. Models were fixed distally in all degrees of freedom.ResultsIn single limb standing condition, the posterior plate group produced the lowest relative displacement (RD) among all the groups (0.01, 0.03 and 0.06 mm). Further nodal analysis of the highest RD fracture group showed a higher mean displacement of 4.77 mm and 4.23 mm in AP and PA lag screws model (p = 0.000). The amounts of stress subjected to these implants, 134.36 MPa and 140.75 MPa were also significantly lower (p = 0.000). There was a negative correlation (p = 0.021) between implant stress and the displacement which signifies a less stable fixation using AP and PA lag screws.ConclusionProgressively increasing fracture size demands more stable fixation construct because RD increases significantly. Posterior buttress plate produces superior stability and lowest RD in PMF models irrespective of the fragment size.     

Biomechanical comparison of tuberosity-based proximal humeral locking plate compared to standard proximal humeral locking plate in varus cantilever bending

PurposeIn a prior biomechanical study using a tuberosity-based proximal humeral locking plate (TBP) an improvement in greater tuberosity (GT) fixation strength with the TBP compared to a standard proximal humeral locking plate (PHLP) was demonstrated. The purpose of this study is to compare the TBP to the PHLP with a simulated calcar gap fracture under cyclic varus cantilever forces.MethodsSeven matched pairs of cadaveric humeri were studied and 11A2.3 proximal humerus fractures were created by a 1 cm gap osteotomy at the surgical neck. Matched pairs were randomized for fixation using either a PHLP or a TBP. The proximal articular aspect of the humerus was potted and secured to the base of a load frame. The shaft was subjected to cyclic varus cantilever loading with a roller positioned 8 cm from the osteotomy. Change in vertical displacement of the diaphyseal fragment was monitored and digital images were obtained. Failure was defined as vertical displacement greater than 20 mm. Specimens not exhibiting failure over the course of 10,000 cycles were then loaded to 20 mm of vertical displacement. Reactant forces of the specimens at these displacements were recorded.ResultsFour/seven TBP specimens and four/seven PHLP specimens survived 10,000 cycles. The average cycles to failure for TBP specimens was 7325 cycles and 5715 cycles for PHLP specimens (p = 0.525). For the specimens that survived 10,000 cycles, the decrease in calcar gap was superior in the TBP specimens (p = 0.018). A similar trend was seen when these specimens were loaded to failure where the percent calcar gap recovery was higher for the TBP at 74.71 ± 10.07% versus 53.22 ± 30.35% for the PHLP (p = 0.072). In specimens that were loaded to failure after survival of 10,000 cycles the average stiffness of the TBP construct was 20.51 N/mm, and 11.74 N/mm for the PHLP construct (p = 0.024).ConclusionIn addition to superior GT fixation shown in a prior study, the TBP construct demonstrates significantly greater stiffness at the neck fracture compared to the PHLP, when loaded to failure. In addition, there was a trend towards less collapse in this calcar gap model.     

The anterolateral supra-fibular-head approach for plating posterolateral tibial plateau fractures: A novel surgical technique

ObjectiveThe posterolateral (PL) tibial plateau quadrant is laterally covered by the fibular head and posteriorly covered by a mass of muscle ligament and important neurovascular structures. There are several limitations in exposing and fixing the PL tibial plateau fractures using a posterior approach. The aim of this study is to present a novel anterolateral supra-fibular-head approach for plating PL tibial plateau fractures.MethodsFive fresh and ten preserved knee specimens were dissected to measure the following parameters:1) the vertical distance from the apex of the fibular head to the lateral plateau surface, 2) the transverse distance between the PL platform and fibula collateral ligament (FCL), and 3) the tension of the FCL in different knee flexion positions. Clinically, isolated PL quadrant tibial plateau fractures were treated via an anterolateral supra-fibular-head approach and lateral rafting plate fixation. The outcome of the patients was assessed after a short to medium follow-up period.ResultsThe distance from the apex of the fibular head to the lateral condylar surface was 12.2 ± 1.6 mm on average. With the knee extended and the FCL tensioned, the transverse distance between the PL platform and the FCL was 6.7 ± 1.1 mm. With the knee flexed to 60° and the FCL was in the most relaxed position, the distance increased to 21.1 ± 3.0 mm. Clinically, a series of 7 cases of PL tibial plateau fractures were treated via this anterolateral supra-fibular-head approach. The patient was placed in a lateral decubitus position with the knee flexed to approximately 60 degrees. After the posterior retraction of the FCL, the plate was placed more posteriorly to provide a raft or horizontal belt fixation of the PL tibial plateau fragment. After an average of 14.3 months of follow up, the knee range of motion(ROM) was 121.4°±8.8° (range: 105°-135°), the HSS score was 96.7 ± 2.6 (range: 90-100), and the SMFA dysfunction score was 22.4 ± 3.8 (range: 16-28) points.ConclusionThe anterolateral supra-fibular-head approach can provide direct visualization of the posterolateral tibial plateau quadrant and put the plate more posteriorly to provide a raft for the fragments such that good clinical outcomes can be anticipated.     

Nerve and tendon injury with percutaneous fibular pinning: A cadaveric study

ObjectiveThe purposes of this study were to measure the average distance from a percutaneous pin in each quadrant of the distal fibula to the sural nerve and nearest peroneal tendon, and define the safe zone for percutaneous pin placement as would be used during surgery.MethodTen fresh-frozen cadavers underwent percutaneous pin fixation into four quadrants of the distal fibula. The sural nerve and peroneal tendon were identified as they coursed around the lateral ankle. Distances from the K-wire in each quadrant to the anatomic structure of interest were measured.ResultsAverage distances (mm) from the K-wire to the sural nerve in the anterolateral, anteromedial, posterolateral, and posteromedial quadrants were 19.1 ± 8.9 (range, 5.1–35.5), 12.8 ± 8.2 (range, 0.3–27.8), 12.6 ± 6.8 (range, 3.0–27.8), and 5.9 ± 5.5 (range, 0.1–19.9), respectively. Average distances from the K-wire to the nearest peroneal tendon in the anterolateral, anteromedial, posterolateral, and posteromedial quadrants were 15.7 ± 4.4 (range, 9.5–23.1), 11.9 ± 5.2 (range, 3.2–21.7), 6.3 ± 3.9 (range, 0.1–14.4), and 1.0 ± 1.6 (range, 0–5.6), respectively.ConclusionsPercutaneous pinning of distal fibula fractures is a successful treatment option with minimal complications. Our anatomical study found the safe zone of percutaneous pin placement to be in the anterolateral quadrant. The sural nerve can be as close as 5.1 mm and the peroneal tendons as near as 15.7 mm. In contrast, the posteromedial quadrant was associated with the greatest risk of injury to both the sural nerve and peroneal tendons.