Locking Plate Construct Research Articles

Interim Analysis of a Prospective Multicenter Study Assessing Radiographic and Patient Outcomes Following a Mini-Open Triplanar Tarsometatarsal Arthrodesis with Early Weightbearing

Category: Bunion; Midfoot/Forefoot Introduction/Purpose: The majority of hallux valgus (HV) corrections have been historically performed via a two-dimensional, transverse plane-focused approach, which has demonstrated high rates of recurrence. Recently there has been a trend towards less-invasive approaches and an instrumented 1st TMT system was developed to perform a triplanar 1st TMT arthrodesis through a mini-open incision. Therefore, the purpose of this study is to assess the radiographic and patient-reported outcomes for HV correction performed with this system through a mini-open approach (≤4cm) with early return to weightbearing. Methods: This is an interim analysis of a prospective multicenter study on patients with symptomatic HV and no prior history of HV surgery on the operative foot. Patients were treated with an instrumented 1st TMT procedure through a mini-open (≤4cm) dorsal incision (which is approximately 50% smaller than the system’s prior-generation open incision) utilizing a biplanar locking plate construct with protected early weightbearing. The primary endpoint of this study is radiographic recurrence of HV, with recurrence reported using two different thresholds commonly utilized in the literature: post-operative HVA >15° and HVA >20°. Changes in radiographic measurements, return to weightbearing and activities, Manchester-Oxford Foot Questionnaire (MOxFQ), patient-reported pain (VAS), and forefoot circumference were also evaluated for statistically significant post-operative improvements through 12-month follow-up. Results: 105 patients (mean [range] age: 41.0 [14-57] years) underwent a mini-open TMTA, with 92 and 70 patients completing 6- and 12-month visits, respectively. Mean (SD) incision length was 3.5cm (0.27). Mean (95% CI) time to protected weightbearing and unrestricted activity were 7.9 (6.7, 9.1) days and 3.6 (3.4, 3.8) months, respectively. Significant improvements in HVA, IMA, and TSP were maintained through 12 months (Table 1). Applying recurrence definitions of HVA >15° and >20°, 12-month recurrence rates were 4.8% (3/62) and 0% (0/62), respectively. Significant improvements in VAS and MOxFQ were observed through 12 months (N =65). Twelve-month mean (95% CI) change in forefoot circumference was -0.8cm (-1.2, -0.5), N =64. One (1.0%) of 105 patients required reoperation (HWR due to pain) and no patients experienced symptomatic nonunion. Conclusion: The interim results of this prospective, multicenter study on a mini-open 1st TMT system with early weightbearing demonstrated statistically significant improvements in radiographic alignment and patient-reported outcomes, and minimal forefoot swelling. This study will follow the patients for a total of 24 months postoperatively.

Bicortical Compression and Construct Stability With Variable Pitch Locking Screws in Cadaveric Specimens.

A variable pitch locking screw is intended to provide interfragmentary compression combined with fixed angle stability of locking plate constructs. The objective of this study was to compare variable pitch locking screws (3.5-mm KreuLock Ti locking compression screws, Arthrex Inc., Naples, FL) with standard locking screws (from the same manufacturer) in bicortical fixation scenarios in cadaver bone by assessing (1) interfragmentary compression and plate-bone compression and (2) construct biomechanical stability. Nine matched pairs of fresh-frozen cadaveric specimens with an average age of 67.2 years (range, 37-83) were used. Interfragmentary compression and plate-bone compression associated with insertion of single bicortical screws were compared between the variable pitch and standard locking screws at increasing levels of torque. The specimens tested were distal tibiae having a simulated longitudinal fracture. Additionally, fibulae were osteotomized to create a stable longitudinal fracture pattern and were fixed with a 5-screw plate construct with either all variable pitch or all standard locking screws. One of the 5 screws was placed across the osteotomy without lagging. Fibulae were tested cyclically with axial with torsional loading to compare displacements, rotation, and loads at failure or tested in 4-point bending to compare construct stiffness and maximum force to failure. Interfragmentary and plate-bone compression forces in the distal tibia model varied across specimens but were significantly higher with variable pitch locking screws compared with standard locking screws [512 N (SD = 324 N) vs. 79 N (SD = 64 N), P = 0.002, and 242 N (SD = 119 N) vs. 104 N (SD = 123 N), P = 0.028, respectively]. In cyclic loading of fibula constructs, no significant differences were detected in construct axial displacement or angular displacement (P > 0.05). In 4-point bending, no differences were detected in maximum force or bending stiffness (P > 0.05). Variable pitch locking screws produced interfragmentary compression between cortices and plate-bone compression that was greater than that produced by standard locking screws. In a stable bicortical fibula fixation scenario under external loading, the stability of variable pitch locking screw constructs was similar to constructs with standard locking screws.

Fracture Compression and Construct Stability with Variable Pitch Locking Screws in Cadaveric Specimens

Category: Trauma; Basic Sciences/Biologics Introduction/Purpose: A variable pitch locking screw is intended to provide interfragmentary compression combined with fixed angle stability of locking plate constructs. The objective of this study was to compare variable pitch locking screws with standard locking screws in bicortical fixation scenarios in cadaver bone, by assessing: (1) interfragmentary compression and plate-bone compression; and (2) construct biomechanical stability. Methods: Nine matched pairs of fresh-frozen cadaveric specimens were used to compare variable pitch locking screws and standard locking screws. First, interfragmentary compression and plate-bone compression associated with insertion of single bicortical screws at increasing levels of torque were measured in distal tibiae having a simulated longitudinal fracture. Second, fibulae were osteotomized to create a stable fracture pattern, fixed with five-screw plated constructs, and tested in either cyclic axial and torsional loading or four-point bending. Results: Interfragmentary and plate-bone compression forces were significantly higher with variable pitch locking screws compared to standard locking screws (p =0.002 & p=0.028, respectively). The amount of compression was variable across specimens. In cyclic loading of fibula constructs, no significant differences were detected in construct axial displacement or angular displacement. In four-point bending, no differences were detected in maximum force or bending stiffness. Conclusion: Variable pitch locking screws can produce high interfragmentary compression between cortices, along with moderate plate-bone compression. In a stable bicortical fixation scenario under external loading, construct stability was similar to normal locking screws.

Locked plate constructs are not necessarily stiffer than nonlocked constructs: A biomechanical investigation of locked versus nonlocked diaphyseal fixation in a human cadaveric model of nonosteoporotic and osteoporotic distal femoral fractures.

The objective of this study was to compare the biomechanical properties of locked and nonlocked diaphyseal fixation in a model of distal femur fractures using osteoporotic and nonosteoporotic human cadaveric bone. A supracondylar osteotomy was created to mimic a fracture (OTA/AO 33A3) in osteoporotic (n = 4) and nonosteoporotic (n = 5) cadaveric distal femurs. The left and right femurs of each pair were instrumented with a distal femoral locking plate and randomly assigned to have diaphyseal fixation with either locked or nonlocked screws. The construct was cyclically axially loaded, and construct stiffness and load to failure were evaluated. In osteoporotic bone, locked constructs were more stiff than nonlocked constructs (mean 143 vs. 98 N/mm when all time points combined, P < 0.001). However, in nonosteoporotic bone, locked constructs were less stiff than nonlocked constructs (mean 155 N/mm vs. 185 N/mm when all time points combined, P < 0.001). In osteoporotic bone, the average load to failure was greater in the locked group than in the nonlocked group (mean 1159 vs. 991 N, P = 0.01). In nonosteoporotic bone, the average load to failure was greater for the nonlocked group (mean 1348 N vs. 1214 N, P = 0.02). Bone mineral density was highly correlated with maximal load to failure (R2 = 0.92, P = 0.001) and stiffness (R2 = 0.78, P = 0.002) in nonlocked constructs but not in locked constructs. Contrary to popular belief, locked plating constructs are not necessarily stiffer than nonlocked constructs. In healthy nonosteoporotic bone, locked diaphyseal fixation does not provide a stiffer construct than nonlocked fixation. Bone quality has a profound influence on the stiffness of nonlocked (but not locked) constructs in distal femur fractures.

Advances in Dynamization of Plate Fixation to Promote Natural Bone Healing.

The controlled dynamization of fractures can promote natural fracture healing by callus formation, while overly rigid fixation can suppress healing. The advent of locked plating technology enabled new strategies for the controlled dynamization of fractures, such as far cortical locking (FCL) screws or active plates with elastically suspended screw holes. However, these strategies did not allow for the use of non-locking screws, which are typically used to reduce bone fragments to the plate. This study documents the first in vivo study on the healing of ovine tibia osteotomies stabilized with an advanced active plate (AAP). This AAP allowed plate application using any combination of locking and non-locking screws to support a wide range of plate application techniques. At week 9 post-surgery, tibiae were harvested and tested in torsion to failure to assess the healing strength. The five tibiae stabilized with an AAP regained 54% of their native strength and failed by spiral fracture through a screw hole, which did not involve the healed osteotomy. In comparison, tibiae stabilized with a standard locking plate recovered 17% of their strength and sustained failure through the osteotomy. These results further support the stimulatory effect of controlled motion on fracture healing. As such, the controlled dynamization of locked plating constructs may hold the potential to reduce healing complications and may shorten the time to return to function. Integrating controlled dynamization into fracture plates that support a standard fixation technique may facilitate the clinical adoption of dynamic plating.

The effect of body weight on interfragmentary fracture strain in plate fixation of distal femur fractures: A finite element analysis

IntroductionDistal femur fractures are difficult to successfully treat due to high rates of nonunion. Obesity is an independent prognostic risk factor for nonunion. Advances in finite element analyses (FEAs) have allowed researchers to better understand the performance and behavior of constructs at the bone-implant interface under a variety of conditions. The purpose of this study is to determine the impact of body weight on fracture strain in a lateral locking plate construct for supracondylar femur fractures and whether additional construct rigidity is beneficial to optimize fracture strain in high body mass patients. HypothesisWe hypothesized that increased loads would produce a higher interfragmentary strain (IFS), which could be decreased by shortening the working length of the construct. Materials and methodsA 3D finite element analysis was performed on two separate femur models with a comminuted supracondylar distal femur fracture fixed with a lateral distal femoral locking plate in bridging mode with Ansys software. Axial forces were varied to recreate the effect of load from normal and high body mass patients. Working length and screw density of the construct were varied for each condition. Measurements of interfragmentary strain and shear motion (SM) were compared. ResultsDoubling the axial load from 70kg (control) to 140kg (high body mass) increased the interfragmentary strain by an average of 76% for the three working lengths (3.38%±1.67% to 4.37%±0.88% at the baseline working length (BWL), 1.42%±1.00% to 2.87%±2.02% at the intermediate working length (IWL) and 0.62%±0.22% to 1.22%±0.42% at the short working length (SWL)). On average, decreasing the working length in the 140kg load reduced the mean IFS to within 15% of the mean IFS of the 70kg load at the longer working length (2.87%±2.02% at IWL 140kg versus 3.38%±1.67% at BWL 70kg and 1.22%±0.45% SWL 140kg versus 1.42±1.00% IWL 70kg). DiscussionIncreased axial load increases interfragmentary strain in an AO/OTA 33A distal femur fracture fixed with a lateral distal femoral locking plate. Decreasing the working length of the fixation construct in the high body mass model decreased interfragmentary strain. Higher loading conditions reflective of high body mass patients should be considered in studies investigating optimization of fracture strain. Level of proofV; Finite Element Analysis (FEA).

Biomechanical Analysis of Combined Medial Calcar and Lateral Locked Plating Versus Isolated Lateral Locked Plating of Proximal Humerus Fractures.

Medial calcar buttress plating combined with lateral locked plating is biomechanically tested against isolated lateral locked plating in synthetic humeri models for the treatment of proximal humerus fractures. Proximal humerus fractures (OTA/AO type 11-A2.1) were manufactured in 10 pairs of Sawbones humeri models (Sawbones, Pacific Research Laboratories, Vashon Island, WA). Specimen were randomly assigned and instrumented with either medial calcar buttress plating combined with lateral locked plating (CP) or isolated lateral locked plating (LP). Nondestructive torsional and axial load tests were performed to evaluate construct stiffness. Large-cycle axial tests were conducted followed by destructive ramp-to-failure tests. Cyclic stiffness was compared in both nondestructive and ultimate failure loads. Failure displacement was recorded and compared between groups. The addition of medial calcar buttress plating to lateral locked plating constructs significantly increased the axial ( P < 0.01) and torsional ( P < 0.01) stiffness of the construct compared with isolated lateral locked plating by 95.56% and 37.46%, respectively. All models demonstrated greater axial stiffness ( P < 0.01) after 5000 cycles of axial compression, not dependent on the fixation method. During destructive testing, the CP construct withstood 45.35% larger load ( P < 0.01) and congruently exhibited 58% less humeral head displacement ( P = 0.02) before failure when compared with the LP construct. This study demonstrates the biomechanical superiority of medial calcar buttress plating when combined with lateral locked plating as compared with isolated lateral locked plating of OTA/AO type 11-A2.1 proximal humerus in synthetic humeri models.

Fibular Autograft as Medial Support with Proximal Humerus Locking Plate Construct in Comminuted Proximal Humerus Fractures: A Retrospective Analysis.

Varus collapse is one of the pivotal mechanisms of failure following surgical fixation of proximal humerus fractures. The aim of the present study was to evaluate functional and radiological outcomes of non-vascularized fibular autograft as medial support with locking plate construct for comminuted proximal humerus fractures (PHF's). We retrospectively evaluated 18 patients with unstable PHF's in the age group 50-70years with a minimum follow-up of two years. All thefracture patterns were classified according to Resch, Neer's and AO classification and either medial calcar compromise or comminution were present in all. Open reduction internal fixation (ORIF) with a locking plate was performed for all thepatients along with intramedullary fibular autograft to support medial calcar. Radiological outcome was assessed by neck-shaft angle (NSA) graded according to the Paavolainen grading method and difference in thehumeral head height (HHH). Functional outcome was assessed by shoulder range of motion (ROM), University of California-Los Angeles (UCLA) score and American shoulder and elbow surgeons score (ASES). Radiological union at the fracture site was achieved in all the patients at mean of 8months (range 6-12months). Range of movements were mean flexion of 123.89, extension 35.28, internal rotation 66.94, external rotation 57.78 and abduction of 115° at final follow-up. The average NSA was in the range of 120°-130° and none of the patients showed difference in HHH of ≥ 4mm in the immediate post-operative radiograph and that taken on final follow-up. The functional outcome assessed by ASES score (mean 89.44) and UCLA score (mean 29.61) suggested fair to good results. None of the patients has shown varus collapse and avascular necrosis. Neither there were any complications related to the donor area. In unstable proximal humerus fractures with calcar comminution or void, PHILOS plate fixation augmented with fibular autograft as a medialsupport reduces varus collapse and promotes early radiological union.

Comparing the torsional resistance of different fixation techniques for spiral metacarpal fractures.

This study aimed to compare the torsional resistance of three fixation techniques for spiral metacarpal fractures: screw-only fixation, screw plus neutralization plate fixation, and a locking plate construct. A spiral fracture was created on 18 cadaveric metacarpal bones by applying an axial and torsional loading force using an Instron 3343 mechanical tester. The failure strength was defined as the native torque strength. The fractures were divided into three groups and fixed using each of the three techniques. The repaired bones were loaded to failure to determine the post-repair strength. The neutralization plate group conferred a post-repair torque (278.6 Nmm) that was similar to the native torque (292 Nmm) with a diminution of only 4.5% and appeared to provide the best resistance to torsion.

Intramedullary Threaded Nail Fixation Versus Plate and Screw Construct in Metacarpal Neck Fractures: A Biomechanical Study.

Indicated surgical management of metacarpal neck fractures varies with techniques, including Kirschner wire fixation, plate fixation, intramedullary fixation, and headless compression screw fixation, without demonstrated superiority. This study compares intramedullary threaded nail (ITN) fixation with a locking plate construct. Index through small finger metacarpals were harvested from 10 embalmed cadavers. After application of appropriate exclusion criteria, remaining metacarpals underwent neck fracture creation by a three-point load to failure. Eight samples were randomly allocated to fixation with ITN fixation, and six were stabilized with a 2.3-mm seven-hole locking plate. Samples were then subjected to a second round of biomechanical testing using the same apparatus. Ultimate load between the intact tissue and the subsequently stabilized fracture was analyzed with a paired Student t -test. Percentage change in ultimate load in the intact tissue and stabilized tissue was calculated, and the magnitude of relative difference between the two groups was analyzed using unpaired Student t -tests. Statistical difference was defined by a P value of < 0.05. Both groups demonstrated the ability to handle a biomechanical load; however, both were significantly weaker than the intact tissue (paired Student t -test p ITN-fixed versus p ITN-intact = 0.006; p plate-fixed versus p plate-intact = 0.002). ITN samples demonstrated a higher load to failure (unpaired Student t -test p ITN-fixed versus p plate-fixed = 0.039). ITN provides a biomechanically stronger fixation constructed for vertically oriented metacarpal neck fractures compared with locking plate fixation. Both ITN and locking plate constructs provide stabilization capable of tolerating a biomechanical load; however, both fixation modalities are weaker than the native tissue.

Olecranon Fracture Fixation: Surgical Technique

Fractures of the olecranon occur from fall on the elbow or the outstretched hand resulting in eccentric contracture of the triceps musculature and subsequent avulsion of the proximal aspect of the ulna. These fractures are both inherently intra-articular and unstable, and therefore surgical repair is generally indicated. We will present two surgical techniques for the repair of olecranon fractures, including tension band wiring and locking plate constructs.

Changes in tibial cortical dimensions and density associated with long-term locking plate fixation in goats

PurposeCortical porosis, secondary to either vascular injury or stress-shielding, is a comorbidity of fracture fixation using compression bone plating. Locking plate constructs have unique mechanics of load transmission and lack of reliance on contact pressures for fixation stability, so secondary cortical porosis adjacent to the plate has not been widely investigated. Therefore, this study aimed to assess the effects of long-term locking plate fixation on cortical dimensions and density in a caprine tibial segmental ostectomy model.MethodsData was acquired from a population of goats enrolled in ongoing orthopedic research which utilized locking plate fixation of 2 cm tibial diaphyseal segmental defects to evaluate bone healing over periods of 3, 6, 9, and 12 months. Quantitative data included tibial cortical width measurements and three-dimensionally reconstructed slab density measurements, both assessed using computed tomographic examinations performed at the time of plate removal. Additional surgical and demographic variables were analyzed for effect on cortical widths and density, and all cis-cortex measurements were compared to both the trans-cortex and to the contralateral limbs.ResultsThe tibial cis-cortex was significantly wider and more irregular than the trans-cortex at the same level. This width asymmetry differed in both magnitude and direction from the contralateral limb. The bone underlying the plate was significantly less dense than the trans-cortex, and this cortical density difference was significantly greater than that of the contralateral limb. These cortical changes were independent of both duration of fixation and degree of ostectomy bone healing.ConclusionsThis study provides evidence that cortical bone loss consistent with cortical porosity is a comorbidity of locking plate fixation in a caprine tibial ostectomy model. Further research is necessary to identify risk factors for locking-plate-associated bone loss and to inform clinical decisions in cases necessitating long-term locking plate fixation.

In vitro analysis and in vivo assessment of fracture complications associated with use of locking plate constructs for stabilization of caprine tibial segmental defects

PurposeLocking plate fixation of caprine tibial segmental defects is widely utilized for translational modeling of human osteopathology, and it is a useful research model in tissue engineering and orthopedic biomaterials research due to its inherent stability while maintaining unobstructed visualization of the gap defect and associated healing. However, research regarding surgical technique and long-term complications associated with this fixation method are lacking. The goal of this study was to assess the effects of surgeon-selected factors including locking plate length, plate positioning, and relative extent of tibial coverage on fixation failure, in the form of postoperative fracture.MethodsIn vitro, the effect of plate length was evaluated using single cycle compressive load to failure mechanical testing of locking plate fixations of caprine tibial gap defects. In vivo, effects of plate length, positioning, and relative tibial coverage were evaluated using data from a population of goats enrolled in ongoing orthopedic research which utilized locking plate fixation of 2 cm tibial diaphyseal segmental defects to evaluate bone healing over 3, 6, 9, and 12 months.ResultsIn vitro, no significant differences in maximum compressive load or total strain were noted between fixations using 14 cm locking plates and 18 cm locking plates. In vivo, both plate length and tibial coverage ratio were significantly associated with postoperative fixation failure. The incidence of any cortical fracture in goats stabilized with a 14 cm plate was 57%, as compared with 3% in goats stabilized with an 18 cm plate. Craniocaudal and mediolateral angular positioning variables were not significantly associated with fixation failure. Decreasing distance between the gap defect and the proximal screw of the distal bone segment was associated with increased incidence of fracture, suggesting an effect on proximodistal positioning on overall fixation stability.ConclusionsThis study emphasizes the differences between in vitro modeling and in vivo application of surgical fixation methods, and, based on the in vivo results, maximization of plate-to-tibia coverage is recommended when using locking plate fixation of the goat tibial segmental defect as a model in orthopedic research.

Assessment of Gait Following Locking Plate Fixation of a Tibial Segmental Defect and Cast Immobilization in Goats

The purpose of this study was to analyze the effects of locking plate fixation used for bridging of tibial segmental ostectomy and of cast immobilization on gait biomechanics in goats. We hypothesized that stable fixation of a segmental bone defect, using a locking plate construct, would result in minimal changes in biomechanical variables of gait in goats, but full-limb immobilization would result in lasting alterations in the immobilized limb’s gait kinetics. A pressure-sensing walkway was used to measure biomechanical characteristics for stride, gait, and walking vertical force. Thirteen, non-lame adult Boer-cross goats were trained to walk over a pressure-sensing walkway prior to instrumentation. Segmental ostectomy was performed on the right hind tibia of each goat and the defect was stabilized using bridging plate fixation with a locking compression plate. Per the protocol of an ongoing orthopedic study, the same goats underwent right hindlimb cast immobilization between one and four months postoperatively. Data was collected preoperatively and then over twelve months postoperatively in goats with unrestricted mobility. Statistical analysis revealed no significant alterations in hindlimb kinematics or maximum force when comparing the period after surgery with that after cast immobilization; significant decreases in forelimb stride length and velocity were noted postoperatively but normalized prior to cast placement, suggesting the overall functional stability of fixation. Cast immobilization had a profound and sustained effect on gait with significant alterations in both forelimb kinetics and hindlimb kinetics and kinematics for the remainder of the trial period; increased hindlimb asymmetry characterized by greater weight distribution and impulse to the left hindlimb was observed, suggesting the potential for long-term and/or permanent detrimental effects of prolonged limb immobilization.

Optimal design and biomechanical analysis of sandwich composite metal locking screws for far cortical locking constructs.

In the interests of more flexible and less stiff bridge constructs to stimulate bone healing, the technique of far cortical locking has been designed to improve locked plating constructs in terms of stress concentration, stress shielding, and inhibition of issues around fracture healing. However, far cortical locking screws currently lack objective designs and anti-fatigue designs. This study investigates an optimization algorithm to form a special locking screw composed of various metals, which can theoretically achieve the maintenance of the excellent mechanical properties of far cortical locking constructs in terms of fracture internal fixation, while maintaining the biomechanical safety and fatigue resistance of the structure. The numerical results of our study indicate that the maximum von Mises stress of the optimized construct is less than the allowable stress of the material under each working condition while still achieving sufficient parallel interfragmentary motion. Numerical analysis of high cycle fatigue indicates that the optimized construct increases the safety factor to five. A high cycle fatigue test and defect analysis indicates that the sandwich locking constructs have better fatigue resistance. We conclude that the sandwich locking construct theoretically maintains its biomechanical safety and fatigue resistance while also maintaining excellent mechanical properties for fracture internal fixation.

Distal femur arthroplasty for non-union distal femur fracture with failed osteosynthesis in osteoporotic octogenarian: a case report with literature review

&lt;p&gt;Distal femur fractures (DFF) in the elderly have high morbidity and management challenges. The low energy trauma commonly presents significant fracture comminution, osteoporosis, pre-existing knee arthritis, co-morbid medical conditions affecting the union, weight-bearing potential and rehabilitation with profound functional disability. An octogenarian presented with a failed osteosynthesis resulting in non-union of a distal femur fracture compounded by osteoporosis and knee arthritis. He had been non-ambulatory with a painful, deformed knee. Management with a single-stage removal of the distal femur locked plate constructs and the defect reconstruction with the distal femur arthroplasty (DFA). The outcome was a pain-free weight-bearing mobilization with a functional range of knee motion. The surgical management in the elderly for the displaced intra-articular distal femur fractures is to restore the limb length and articular congruence for a functional knee. Fixation with either a distal femur locking plate or an intramedullary nail has a propensity for non-union, malunion, knee stiffness, and failed fixation. Salvage procedure gives good functional outcomes in failed osteosynthesis with DFA. The arthroplasty allows an immediate pain-less weight-bearing potential with improved ambulatory status and quality of life. The single-stage procedure in the elderly can regain a stable, functional knee joint. &lt;/p&gt;

Outcomes of AO/OTA C-type fractures of the distal humerus after open reduction and internal fixation with locking plate constructs in patients at least 65 years old

BackgroundModern treatment options of distal humerus fractures of active elderly patients are osteosynthesis and total elbow arthroplasty. The evidence of outcomes of ORIF after AO/OTA C-type fractures mostly predates the adoption of locking plates. We evaluated the results of open reduction and internal fixation of these fractures treated exclusively with anatomic locking plates.MethodsA retrospective cohort of 39 patients aged 65 years or above with ORIF for AO/OTA C-type distal humerus fracture using locking plates was analysed. 23 provided follow-up data and 14 attended a follow-up visit. Primary outcome was the Oxford Elbow Score. Secondary outcomes were Mayo Elbow Performance Score, quickDASH, satisfaction, range of motion, complications and revision surgeries.ResultsMean Oxford Elbow Score pain was 83 (SD 17), Oxford Elbow Score function 83 (17) and Oxford Elbow Score social-psychological 79 (20). Mean total Oxford Elbow Score was 81 (15). Among the 14 patients who attended a follow-up visit, Mayo Elbow Performance Score was 85 (17), qDASH 19 (16), active arc of motion 119 (19) degrees. Mayo Elbow Performance Score and arc of motion were worse than on the healthy side. One patient had a serious deep infection. Eleven patients had at least one revision surgery, of which 6 were implant removals and 2 subsequent total elbow arthroplasties.ConclusionsDistal AO/OTA C-type distal humerus fractures in older adults can be treated reliably and with good outcomes with ORIF using modern locking plates. The mean qDASH scores are similar to population normal values, but when compared to the healthy arm, single-arm outcomes indicated somewhat impaired function. About 1 in 4 patients had at least one revision surgery.

Influence of the Near-Cortical Over-Drilling Technique on the Mechanical Behaviour of Locking Plate Constructs Applied in Maned Wolf's Femur.

The aim of this study was to evaluate the influence of near-cortical over-drilling holes on the mechanical behaviour of locking plate constructs applied in maned wolf's femur by using mechanical testing and finite element method (FEM). Seven pairs of adult maned wolves (Chrysocyon brachyurus) femur bones were randomly distributed into four groups. In all groups, a 3.5 mm locking compression plate, designed with 12 combi-holes and one locked, was applied to the lateral surface of the femur. G1 (n = 4) received bicortical locking screws placed in holes 1, 3, 5, 8, 10 and 12. In G2 (n = 5), the plate was applied as used in G1, but the application of the locked screws involved the near-cortical over-drilling technique. In G3 (n = 4), the plate was applied as used in G2, but the size of the near-cortical over-drilling was larger. The combi-holes 6 and 7 were maintained over a 10 mm fracture gap without screws. All constructs were tested for failure in the axial load. The axial load was applied eccentrically to the femoral head. Statistical differences were observed in the maximum load with G3 > G1 and G3 > G2, and in the deflection with G2 > G1 and G2 > G3. The FEM showed the lowest total displacement of the bone-plate constructs as well as of the plate in G1 compared with G2 and G3. The near-cortical over-drilling technique used in unstable fractures induced in the maned wolf's femur showed by static axial compression test that maximum load and deflection are dependent on drill hole size induced in the near-cortex. Based on FEM, the lowest total displacement of the bone-plate constructs was observed in Group 1.

Biomechanical Comparison of Use of Two Screws versus Three Screws Per Fragment with Locking Plate Constructs under Cyclic Loading in Compression in a Fracture Gap Model

Abstract Objectives The aim of this study was to measure and compare the stiffness and cyclic fatigue of two plate-bone model constructs, with either two or three locking screws per fragment, under cyclic compression. Methods A 10-hole 3.5 mm stainless steel locking compression plate (LCP) was fixed 1 mm from a synthetic bone model in which the fracture gap was 47 mm. Two groups of 10 constructs, prepared with either two or three bicortical locking screws placed at the extremities of each fragment, were tested in a load-controlled compression test until failure. Results The three-screw constructs were stiffer than the two-screw constructs (196.75 ± 50.48 N/mm and 102.43 ± 22.93 N/mm, respectively) and the actuator displacements of the two-screw constructs were higher (18.02 ± 1.07 mm) than those of the three-screw constructs (14.48 ± 2.25 mm). The number of cycles to failure of the two-screw constructs was significantly lower (38,337.50 ± 2,196.98) than the that of the three-screw constructs (44,224.00 ± 1,515.24). Load at irreversible deformation was significantly lower in the two-screw constructs (140.93 ± 13.39 N) than in the three-screw constructs (184.27 ± 13.17 N). All constructs failed by plate bending at the gap between the two cylinders. Clinical Significance Omission of the third innermost locking screw during bridging osteosynthesis subjected to compression forces led to a 13.3% reduction in the number of cycles to failure and a 23.5% reduction of the load withstood by the plate before plastic deformation occurred.

Optimal Design and Biomechanical Analysis of a Biomimetic Lightweight Design Plate for Distal Tibial Fractures: A Finite Element Analysis

The treatment of fractures of the distal tibia can be problematic due to the insubstantial soft-tissue covering this part of the anatomy. This study investigates a novel strategy for minimally invasive plate osteosynthesis of distal tibia fractures called bionic lightweight design plating. Following the structure of the animal trabecular bone, we utilized topological mathematical methods to redesign the material layout of the internal fixation device to fulfill the desired lightweight design within given boundary conditions. The results showed that this method can maintain the same stability of the construct as the original plate after a reduction in the original volume by 30%, and the differences in strain energy of plates and maximum node displacement of constructs between the constructs [RP construct vs. LP construct] were not statistically significant (p > 0.05). In the safety assessment of the constructs, the peak stress of plates between constructs was found to not be statistically significantly different under a doubled physiological load (p > 0.05). The average stress of the plates’ elements exceeding the allowable stress was analyzed, and no statistically significant differences were found between the two constructs under axial compression stress conditions (p > 0.05). The average stress of the plates’ elements in the redesigned plating construct under torsional stress conditions was 3.08% less than that of the locked plating construct (p < 0.05). Under the double physiological load condition, 89% of the elements of the plate in the redesigned plating construct and 85% of the elements of the plate in the locked plating construct were lower than the maximum safe stress of the plate, which was 410 MPa (secondary allowable stresses). That reminds us the topology optimization offer a possible way to improve the capacity of soft tissue protection while ensuring the safety of the RP construct by reducing the volume of the implants.