Longer Working Length Research Articles

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).

Feasibility of Rescue Colonoscopy Using a Short-type Enteroscope (SIF-H290S) without Overtube after Incomplete Colonoscopy: A Single-center Retrospective Pilot Study.

Recently, a newly designed short-type single-balloon enteroscope (SBE), SIF-H290S, has been developed with a smaller outer diameter and a longer working length than conventional colonoscopes. It has passive bending and high-force transmission, making insertion easier. However, it is difficult to perform rescue colonoscopy with an SBE after incomplete colonoscopy in the same session. Therefore, this study evaluated the feasibility of consecutive rescue colonoscopy using SIF-H290S without overtube after incomplete colonoscopy. This was a single-center retrospective study. We included 19 rescue colonoscopies (19 patients) with SIF-H290S without overtube performed by 11 endoscopists in the SIF group and 38 rescue colonoscopies (38 patients) using a small-caliber colonoscope (PCF-PQ260L) were randomly selected for the control group from procedures performed by the same 11 endoscopists. We compared the cecal intubation rate and other outcomes, such as insertion time, between the two groups. The median age of the patients was 72 and 69 years, with 8 and 26 males in the SIF and control groups, respectively. The median body mass index was 21.6 and 22.7 kg/m2 in the SIF and control groups, respectively. There were no significant differences in the patient backgrounds between the groups, except for the reason for incomplete colonoscopy (p = 0.048). The cecal intubation rate was 78.9% (15/19 procedures) and 92.1% (35/38 procedures) in the SIF and control groups, respectively. This study revealed the real-world experience and feasibility of rescue colonoscopy using SIF-H290S, which could be a potential rescue device option after incomplete colonoscopy.

Outcomes of Gore iliac branch endoprosthesis with internal iliac component versus Gore Viabahn VBX

ObjectiveThe Gore Excluder iliac branch endoprosthesis (IBE; W.L. Gore & Associates, Flagstaff, AZ) is the only iliac branch device approved in the United States to preserve blood flow to the external and internal iliac arteries (IIAs). Some surgeons have used the Gore Viabahn VBX balloon expandable endoprosthesis (VBX; W.L. Gore & Associates) in the IIA rather than the self-expanding endograft designed for the IBE, the internal iliac component (IIC). The objective of the present study was to examine the outcomes for patients treated for aortoiliac artery aneurysms using the IBE with either the IIC or VBX stent. MethodsWe performed a retrospective, single-center review of patients treated for aortoiliac artery aneurysms using the Gore IBE device, with either the IIC or VBX stent into the IIA, from February 2016 to March 2021. The patient demographics, procedure details, 30-day morbidity and mortality, and 6-month and 1-year outcomes and mortality were analyzed. The categorical factors are summarized using frequencies and proportions. Continuous measures are summarized as the mean ± standard deviation. A significance level of P = .05 was assumed for all test results. The analyses were performed using SAS software, version 9.4 (SAS Institute, Cary, NC). ResultsA total of 62 patients (64 arteries) had undergone elective aortoiliac artery aneurysm repair with the IBE. The IIC was used exclusively in 35 cases (55%) and the VBX in 29 (45%). The patients who had received the VBX had had a higher American Society of Anesthesiologists class (P = .006). Upper extremity access was used for VBX delivery in 24.1% of the procedures. No return to the operating room was required in either group. No differences were found in technical success (IIC, 97.1%; VBX, 93.1%; P = .59), the presence of endoleak on completion (20.0% vs 6.9%; P = .17), readmission (97.1% vs 93.1%; P = .59), or mortality (1.6% vs 0%; P = .45) at 30 days. No differences were found in the requirement for any IBE reintervention after 30 days. No type Ia, Ib, or III endoleaks had occurred in either group at any follow-up point. No significant difference was found in internal iliac limb primary patency (IIC, 100%; VBX, 96.3%) between groups. A nonstatistically significant trend was found toward fewer trunk–ipsilateral leg type II endoleaks in the VBX group during follow-up. ConclusionsThese data suggest that the VBX is a reasonable substitute for the IIC, with a comparable safety and efficacy profile. Given its inherent conformability, greater range of diameters, and longer working length, the VBX stent offers expanded IIA branch options with the IBE.

DISTAL FEMORAL FRACTURES FROM HIGH-ENERGY TRAUMA: A RETROSPECTIVE REVIEW OF COMPLICATION RATE AND RISK FACTORS.

Determine complications' incidence and risk factors in high-energy distal femur fractures fixed with a lateral locked plate. Forty-seven patients were included; 87.2% were male, and the average age was 38.9. The main radiographic parameters collected were distal lateral femoral angle (DFA), distal posterior femoral angle (DPLF), comminution length, plate length, screw working length, bone loss, and medial contact after reduction and plate-bone contact, location of callus formation, and implant failure. The complications recorded were nonunion, implant failure, and infection. Complex C2 and C3 fractures accounted for 85.1% of cases. Open fractures accounted for 63.8% of cases. The mean AFDL and AFDP were 79.8 4.0 and 79.3 6.0, respectively. The average total proximal and distal working lengths were 133.3 42.7, 60.4 33.4, and 29.5 21.8 mm, respectively. The infection rate was 29.8%, and the only risk factor was open fracture (p = 0.005). The nonunion rate was 19.1%, with longer working length (p = 0.035) and higher PDFA (p = 0.001) as risk factors. The site of callus formation also influenced pseudoarthrosis (p = 0.034). High-energy distal femoral fractures have a higher incidence of pseudoarthrosis and infection. Nonunion has greater working length, greater AFDL, and absence of callus formation on the medial and posterior sides as risk factors. The risk factor for infection was an open fracture. Level of Evidence III; Retrospective Cohort Study .

The effects of locking inserts and overtorque on the mechanical properties of a large fragment locking compression plate

PurposeThe study was to determine the effect of locking hole inserts and their insertion torque on the fatigue life of a large fragment Locking Compression Plate (LCP) under bending forces.MethodsFatigue strength of the LCP was examined using cyclic three-point bend testing at 80% yield strength of the construct. Locking hole inserts were used in 2, 4, and 6-hole of a 12-hole plate to simulate three different working lengths. Within each working length, plates were tested without locking inserts serving as the control group. In the experimental groups, inserts were tightened to manufacturer recommendations (4 Nm) and using overtorque (8 Nm).ResultsSignificantly fewer cycles to failure were observed in control groups versus the locking hole insert groups for all working lengths (2-hole: 4 Nm p = 0.003, 8 Nm p = 0.003; 4-hole: 4 Nm p = 0.02, 8 Nm p < 0.001; 6-hole: 4 Nm p = 0.004, 8 Nm p < 0.001). There was a statistically significant increase in fatigue strength when using overtorque in the 4-hole (p = 0.04) and 6-hole (p = 0.01) defect groups. This was not shown in the 2-hole defect group (p = 0.99).ConclusionsBy placing locking inserts in the empty locking regions of Combi holes along the working length, the number of cycles to failure was increased. Tightening inserts to twice the recommended insertion torque further increased cycles to failure in longer working length models. A longer fatigue life has the potential to decease the incidence of plate failure especially in the setting of delayed union due to poor intrinsic healing capacity, fractures in the geriatric population, osteoporosis and periprosthetic fractures.

Closure of the femoral medullary canal after retrograde nailing using an in-situ osteochondral autograft–Technical trick and a case series

Retrograde intramedullary nailing (RIMN) is the favored over antegrade intramedullary nailing in fractures of the distal femur. It provides a longer working length and allows for multiple distal screw insertion and therefore a more stable construct. Concerns remain regarding the violation of the knee cartilage and the effect this has on knee function. Many studies have shown high incidence of knee pain with reports varying from 20 to 86%. We describe a novel technical trick aiming at partially restoring the knee cartilage of the operated side and decreasing the hemorrhage stemming from the medullary canal. Our experience of the technique and the case series shows that closing the entrance point of the medullary canal after a RIMN procedure leads to better function and less knee pain in the postoperative period.

Effect of Plate Type and Working Length on a Synthetic Compressed Juxta-Articular Fracture Model

Abstract Objective This investigation compared the biomechanical properties of a 2.0 mm locking compression notched head T-plate (NHTP) and 2.0 mm straight locking compression plate (LCP), in a compressed, short, juxta-articular fragment fracture model. Methods Two different screw configurations were compared for the NHTP and LCP, modelling short (configuration 1) and long working length (configuration 2). Constructs were tested in compression, perpendicular and tension four-point bending and torsion. Plate surface strain was measured at 12 regions of interest using three-dimensional digital image correlation. Stiffness and strain were compared. Results The LCP was stiffer than the NHTP in all three planes of bending (p &lt; 0.05). The NHTP was stiffer than the LCP in torsion (p &lt; 0.05). The NHTP had greater strain than the LCP during compression bending and torsion (p &lt; 0.0005). The short working length NHTP was stiffer in all three planes of bending and in torsion (p &lt; 0.05) than the longer working length. The short working length LCP was stiffer in compression bending and in torsion (p &lt; 0.05) than the longer working length. The long working length showed greater strain than the short working length at multiple regions of interest. Conclusion In this experimental model of a compressed transverse fracture with a juxta-articular 9 mm fragment, a 2.0 mm LCP with two hybrid screws in the short fragment was stiffer than a 2.0 mm NHTP with three locking screws in the short fragment in three planes of bending but not torsion. Extending the working length of each construct reduced construct stiffness and increased plate strain.

Early fixation failure of locked plating in complex distal femoral fractures: Root causes analysis

Orthopaedic Trauma Association (OTA) C-type distal femoral fractures can be very challenging to treat effectively. While locked plating is widely used in the complex distal femoral fracture, failure of locked plate fixation is not uncommon. First, we tried to determine the risk factor related to early failure of multiplanar OTA C-type fracture in the distal femur after fixation with lateral locked plate. Second, we tried to provide a strategy for surgeons to prevent pitfalls of early failure in the complex distal femoral fractures treated with lateral locked plating. We retrospectively reviewed 44 adults with OTA C-type fractures of the distal femur treated with locked plate fixation between 2010 and 2016at Tri-Service General Hospital. Average length of follow-up was 27.6 months (range, 12-54 months). Univariate and multivariate logistic regression were used to determine the association of variables on early failure of fixation. A p-value < 0.05 in univariate and multivariate analyses were considered significant. There were six patients experiencing early failure, and the early failure rate was 13.6%. The risk factors associated with early failure of complex distal femoral fracture identified by univariate analysis included sagittal oblique fracture pattern, longer working length and post-operative sagittal malalignment (odds ratio [OR] and 95% confidence intervals [CI]: 90.00 (6.85-1183.33), 0.55 (0.31-0.98) and 8.63 (1.077-69.075) respectively). The multivariate analysis showed only sagittal oblique fracture pattern was associated with early failure [OR: 52.348 (3.06-895.23)]. Sagittal oblique fracture was more likely to result in early postoperative failure. Early recognition of the fracture pattern should be considered to avoid catastrophic results.

Effect of semi-rigid locking screws on the stiffness of a fracture-fixation construct: A conceptual finite-element study

Strong stiffness provided by locking-plate system has resulted in nonunion and delayed union for long bone fracture. Longer bone plate can lengthen the working length to reduce the structural stiffness of the fixation device but will enlarge skin incision. Using the semi-rigid locking screw may be helpful but the efficacy was unclear. In simulated fracture model, four rigid locking screws were continually inserted beneath the fracture gap. The other four rigid/semi-rigid locking screws were equally distributed or concentrated at screw holes superior to the fracture gap. Axial compressive load was exerted to compare the biomechanical performance under various screw configurations and plate working length. Results revealed that using the semi-rigid locking screws, the structural stiffness of the fixation structure were lowered by 29.5%–45.1% comparing to the model with the same screw configuration using rigid locking screws. Semi-rigid screw models with shorter working length represented comparable flexibility of the fixation structure to the rigid locking screw model with longer working length. Compared to rigid locking screw, semi-rigid locking screw may provide similar flexibility with shorter bone plate, which may be beneficial to reduce the required plate length so that the skin incision may be minimized for fracture reduction.

Proximal Screw Configuration Alters Peak Plate Strain Without Changing Construct Stiffness in Comminuted Supracondylar Femur Fractures.

Assess the effect of proximal screw configuration on the strain in lateral plating of a simulated comminuted supracondylar femur fracture. Fractures were simulated in 12 synthetic femurs by removing a 200-mm section of bone, located 60 mm from the intercondylar fossa and repaired using a 16-hole locked lateral plate instrumented with 8 uniaxial strain gauges. Three proximal screw type configurations were evaluated: (1) 4 nonlocking screws, (2) 4 locking screws, and (3) a hybrid configuration of 2 nonlocking screws flanked by a locking screw at each end of the proximal fragment. Each screw type was compared for 2 working lengths (∼90 and 160 mm). The longer working length was created by removing the proximal screw closest to the fracture gap. Testing consisted of a vertical load (500 N) applied to the head of femur. Configurations were compared using plate strain, construct stiffness, and fracture gap displacement as outcome measures. Plate strain immediately above the fracture gap was reduced with nonlocking screws compared with the other screw types. Plate strains were reduced around the fracture gap with the longer working length but increased for the nonlocking construct at the location of the removed screw. Construct stiffness was not altered by screw type or working length. An increase in fracture gap displacement was only evident in shear translation with the longer working length. Plate strain in lateral plating of supracondylar femur fractures is decreased using nonlocking screws proximal to the fracture. Increasing the working length reduces plate strains over the working length yet should be cautioned because of increased interfragmentary shear motion.

The Challenge of Plate-Bone Construct Stiffness: A Swinging Pendulum: Commentary on an article by Michael Bottlang, PhD, et al.: "Dynamic Stabilization with Active Locking Plates Delivers Faster, Stronger, and More Symmetric Fracture-Healing".

Fracture plating has evolved in parallel with better understanding of the biology and mechanics of bone healing. Although treatment of the simple plane fracture with compression plating and absolute stability has been successful in most instances, clinicians still largely rely on experience and judgment to decide how to best treat comminuted fractures and fractures in osteoporotic bone where compression is not an option. Stephan M. Perren’s strain theory1 and studies that followed have taught us that, for bone to heal, there needs to be an ideal amount of micromotion at the fracture site. Too much, and the callus never consolidates; too little, and no bone is formed. Locking fixation seemed to be an excellent solution to the problem of poor fixation in osteoporotic bone; however, with its use in some instances, we created a new problem of constructs with such stiffness that osteocytes at the fracture are not signaled to form callus1,2. One solution to this new problem has been far cortical locking, where the near cortex is effectively overdrilled to allow for increased micromotion while still using locking screws to maintain the benefits of fixed angle stability. This technique arose from the observation that healing callus in locked constructs is often seen …

Is Social Status Related to Internet Pornography Use? Evidence from the Early 2000s in the United States.

While most studies on Internet pornography focus on individual's psychological characteristics, few have explored how social status itself is associated with Internet pornography use. As the Internet is becoming increasingly prevalent, online behaviors may have started to reflect the inequalities of the offline world. This study tested whether lower social status was associated with fewer sexual intercourse opportunities, and whether this led to higher likelihood of using Internet pornography as an alternative means of sexual release. To test the theory, I used the nationally representative sample of the General Social Survey of the U.S. between 2000 and 2004, with missing data handled by chained multiple imputation. The analyses found that lower income, longer working length, being unemployed, or a laborer in the social class strata were associated with fewer sexual intercourse opportunities as measured by three variables: marital status, the number of sex partners, and sex frequency. Lower income, less education, and longer working length were also associated with higher odds of using Internet pornography in the past 30 days, but only income was partially mediated by marital status. Social status was associated with Internet pornography use and sexual intercourse opportunities independently. The comparison of Internet pornography with the traditional X-rated movie found the unique features of Internet pornography use absent for X-rated movie.

The Use of Far Cortical Locking Constructs for Fixation of Periprosthetic Fractures

Locked plate constructs used for fixation of periprosthetic fractures show high rates of healing difficulties. This is especially true in the distal femur, where modern studies show a revision rate of 15% to 22%. The combination of residual fracture gaps created by using biological fixation techniques and the high stiffness of locked plates is thought to result in decreased motion at the fracture site. Concern that the increased stiffness of locked plates contributes to the high nonunion rate lead to changes in the surgical technique (longer working length) and implant materials (titanium). These changes result in plate bending at the fracture site and induce callus at the cortex opposite the plate, with very little callus forming at the cortex near the plate. Far cortical locking (FCL) was developed out of the need to decrease construct stiffness and increase callus formation by allowing symmetric fracture site motion within the optimal range for secondary bone healing. The use of FCL constructs requires only minor changes in surgical technique from standard locked plating. Early outcomes using FCL screws for both nonperiprosthetic and periprosthetic fractures suggest the screws are safe in osteoporotic bone with increased callus formation and no screw breakage or pull out.

Ex vivo cyclic mechanical behaviour of 2.4 mm locking plates compared with 2.4 mm limited contact plates in a cadaveric diaphyseal gap model

To compare the mechanical properties of locking compression plate (LCP) and limited contact dynamic compression plate (LC-DCP) constructs in an experimental model of comminuted fracture of the canine femur during eccentric cyclic loading. A 20 mm mid-diaphyseal gap was created in eighteen canine femora. A 10-hole, 2.4 mm stainless steel plate (LCP or LC-DCP) was applied with three bicortical screws in each bone fragment. Eccentric cyclic loadings were applied at 10 Hertz for 610,000 cycles. Quasistatic loading / unloading cycles were applied at 0 and 10,000 cycles, and then every 50,000 cycles. Structural stiffness was calculated as the slope of the linear portion of the load-displacement curves during quasistatic loading / unloading cycles. No bone failure or screw loosening occurred. Two of the nine LCP constructs failed by plate breakage during fatigue testing, whereas no gross failure occurred with the LC-DCP constructs. The mean first stiffness of the LCP constructs over the course of testing was 24.0% lower than that of constructs stabilized by LC-DCP. Construct stiffness increased in some specimens during testing, presumably due to changes in bone-plate contact. The first stiffness of LC-DCP constructs decreased by 19.4% and that of locked constructs by 34.3% during the cycling period. A biphasic stiffness profile was observed: the second stiffness was significantly greater than the first stiffness in both groups, which allowed progressive stabilization at elevated load levels. Because LCP are not compressed to the bone, they may have a longer working length across a fracture, and thus be less stiff. However, this may cause them to be more susceptible to fatigue failure if healing is delayed.