Purpose: Given recent evolving guidelines regarding maximum allowable work hours and emphasis on resident quality of life, novel strategies are required for implementing call schedules. The night float system has been used by some institutions as a strategy to decrease the burden of call on resident quality of life in level one trauma centres. The purpose of this study was to determine whether there are differences in quality of life, work-related stressors, and educational experience between orthopaedic surgery residents in the night float and standard call systems at two level one trauma centres.

Method: This was a prospective cohort study at two level one trauma hospitals comprised of a standard call (1 in 4) group and a night float (5pm-7am, Sunday to Friday) group for each hospital, respectively. Residents completed the Short Form 36 (SF-36) general quality-of-life questionnaire, as well as, questionnaires on stress level and educational experience before the rotation (baseline), at two, four and subsequently at six months. An analysis of covariance (ANCOVA) approach was used to compare between-group differences using the baseline scores as covariates. Wilcoxon Signed-Rank tests (non-parametric) were used to determine if the residents’ SF-36 scores were different from the age and sex matched Canadian norms. Predictors of resident quality of life were analyzed using multivariable mixed models.

Results: Seven residents were in the standard call group and nine in the night float group for a total of 16 residents (all males, mean age=35.1 yrs). Controlling for between-group differences at baseline, residents on the night float rotation had significantly lower role physical (RP), bodily pain (BP), social function (SF) subscale scores (p< 0.05).

Conclusion: Our study suggests that the residents in the standard call group had better health related quality of life in comparison with the night float group. No differences existed in subjective educational benefits and stress level between the groups. The study findings may be limited due to the small sample size. However, this sample size is substantial given the size of most orthopaedic residency programs in North America.

Purpose: There is growing support in the medical literature that patient outcomes are adversely affected by physician fatigue in operator-dependent cognitive and technical tasks. The recent increase in total joint arthroplasty case load has resulted in longer operative days and increased surgeon fatigue. The purpose of this study was to determine if time of day predicts perioperative outcomes and complications in total hip and knee arthroplasty surgery.

Method: The records of all primary Total Hip Arthroplasty (THA) and Total Knee Arthroplasty (TKA) surgery performed for primary osteoarthritis, during 2007 at one large university hospital, were retrospectively reviewed. Complete demographic data (age, gender, Body Mass Index), start time of surgery, intraoperative complications, duration of surgery, radiographic component alignment, and functional outcome scores (SF-12 and WOMAC) for 341 THA and 292 TKA patients were collected and analyzed using linear and nonparametric rank correlation statistics. Data was corrected for gender, body mass index (BMI), surgeon, and post-call operating days.

Results: In the THA cohort, a later start time of surgery was significantly related to duration of surgery (p=0.0013). In addition, there was a trend towards significance for intraoperative femur fracture (p=0.0542) later in the day. Postoperative complications, component alignment, and functional outcome scores were not significantly affected by start time of surgery. There were no significant findings for any of the intraoperative or postoperative outcomes in the TKA cohort.

Conclusion: This study demonstrates that duration of surgery and the incidence of intraoperative complications for THA may increase as the start time of surgery becomes later in the day. These findings should be taken into consideration when planning operative days involving THA.

Purpose: Surgeons performing hip resurfacing antevert and translate the femoral component anteriorly to maximize head/neck offset and reduce impingement. The anterior femoral neck is under tensile forces during gait similarly to the superior neck [6]. This study was designed to determine the risk of femoral neck fracture after anterior or posterior notching of the femoral neck.

Method: Forty seven fourth generation synthetic femora were implanted with Birmingham Hip Resurfacing prostheses (Smith & Nephew Inc. Memphis, USA). Implant preparation was performed using imageless computer navigation (VectorVision SR 1.0, BrainLAB, Germany). The prosthesis was initially planned for neutral version and translated anterior, or posterior, to create a femoral neck notch. The femora were fixed in a single-leg stance and tested with axial compression using a mechanical testing machine. This method enabled comparison with previously published data. The synthetic femora were prepared in eight experimental groups:two mm and five mm anterior notches, two mm and five mm posterior notches, neutral alignment with no notching (control), five mm superior notch, five mm anterior notch tested with the femur in 25° flexion and five mm posterior notch tested with the femur in 25° extension We tested the femora flexed at 25° flexion to simulate loading as seen during stair ascent. [3] The posterior five mm notched femoral necks were tested in extension to simulate sporting activities like running. The results were compared to the control group in neutral alignment using a one – way ANOVA:

Results: Testing Group Mean load to failure Significance (p-value) Anterior 2mm 3926.61 ± 894.17 .843 Anterior 5mm 3374.64 ± 345.65 .155 Neutral (Control) 4539.44 ± 786.44 – Posterior 2mm 4208.09 ± 1079.81 .994 Posterior 5mm 3988.06 ± 728.59 .902 Superior 5mm 2423.07 ± 424.17 .001 Anterior 5mm in 25° flexion 3048.11 ± 509.24 .027 Posterior 5mm in 25° extension 3104.62 ± 592.67 .038 Our data suggests that anterior and posterior two mm or five mm notches are not significantly weaker in axial compression. Anterior and posterior 5mm notches are significantly weaker in flexion/extension (p=0.027/ p=0.038). The five mm superior notch group was significantly weaker with axial compression supporting previous published data (p=0.001).

Conclusion: We conclude that anterior or posterior two mm notching of the femoral neck has no clinical implications, however five mm anterior or posterior femoral neck notching significantly weakens the femoral neck. Fracture is more likely to occur with stair ascent or activities involving weight bearing in extension. Hip resurfacing is commonly performed on active patients and five mm neck notching has clinically important implications.

Purpose: In recent years, there has been an increased appreciation of the importance of intimate partner violence (IPV), which is also known as domestic violence, spouse abuse, and battering, as a serious public health problem. Domestic violence is the most common cause of nonfatal injury to women in North America. As providers of musculoskeletal care and first-contact health care practitioners for many patients, orthopaedic surgeons should be knowledgeable regarding screening and possible interventions for IPV victims. The Canadian Orthopaedic Association and the American Academy of Orthopaedic Surgeons have both prepared explicit statements that orthopaedic surgeons should play a role in the screening and appropriate identification of victims of IPV. We aimed to identify the knowledge, attitudes, and beliefs about IPV among orthopaedic surgeons who are members of the Orthopaedic Trauma Association.

Method: We surveyed members of the Orthopaedic Trauma Association to identify attitudes toward IPV by posting a survey on the Orthopaedic Trauma Association website for its membership to complete. The survey consisted of three sections:

the general attitude of the orthopaedic surgeon toward intimate partner violence,

Results: One-hundred-and-fifty-three orthopaedic surgeons responded. The majority of the respondents were male (99%) with practices in North America (96%). Surgeons underestimated the prevalence of IPV in their practices and communities and manifested several key misconceptions:

victims must be getting something out of the abusive relationships (16%);

In the past year, approximately half of the surgeons (50.8%) acknowledged identification of a victim of IPV; however, only 4.0% of respondents currently screened for IPV among female patients with injuries. Surgeons expressed concerns about lack of knowledge in the management of abused women (30%) Guidelines for the detection and management of IPV were uncommon in most surgeons’ practices (7.8%).

Conclusion: There is a strong rationale for addressing IPV as an issue that is relevant to the field of orthopaedic surgery just as it has been shown to be relevant to primary care, emergency medicine, and obstetrics and gynecology. Our study found that orthopaedic surgeons underestimated the prevalence of IPV in their practices, held multiple misperceptions about IPV, and demonstrated discomfort in identifying and treating IPV. Targeted educational programs on IPV are needed for surgeons who routinely care for injured women.

Purpose: Intimate partner violence (IPV), also known as domestic violence, is a pattern of coercive behaviors that include repeated physical, sexual and emotional abuse. Musculoskeletal injuries are common manifestations of IPV. We aimed to determine the proportion of women presenting to orthopaedic fracture clinics for treatment of orthopaedic injuries that have experienced IPV defined as physical, sexual, or emotional abuse within the past 12 months.

Method: We completed a cross-sectional study of 282 injured women attending two Level I trauma centres in Canada. Female patients presenting to the orthopaedic fracture clinics completed two validated self-reported written questionnaires (Woman Abuse Screening Tool (WAST) and the Partner Violence Screen (PVS)) to determine the prevalence of IPV. The questionnaire also contained questions that pertain to the participant’s demographic, fracture characteristics, and experiences with health care utilization.

Results: The overall prevalence of IPV (emotional, physical, and sexual abuse) within the last 12 months was 32% (95% Confidence Interval 26.4% to 37.2%) (89 of 282 women). One in 12 injured women disclosed a history of physical abuse (24/282, 8.5%) in the past year. Seven women (2.5%) indicated the cause for their current visit was directly related to physical abuse, of which five were fractures. We did not identify any significant trends in ethnicity, socioeconomic status, or injury patterns as markers of domestic abuse. Of 24 women with physical injuries, only four had been asked about IPV by a physician, none of whom were their treating orthopaedic surgeons.

Conclusion: Our study confirms a high prevalence of IPV among female patients with injuries attending orthopaedic surgical clinics in Ontario. Similar to previous research our study found that women of all ages, ethnicities, social economic status, and injury patterns may experience IPV. Surgeons should consider screening all injured women for domestic violence in their clinics.

Purpose: The purpose of this study was to evaluate the accuracy and precision of 3 common methods used to produce posterior tibial slope during total knee arthroplasty.

Method: The study population consisted of 110 total knee arthroplasties in 102 patients that underwent total knee arthroplasty. All procedures were performed using a standard medial parapatellar approach and all knees were replaced using the Scorpio Knee System (Stryker, Mahwah, NJ) of implants and instruments. Three treatment groups were identified retrospectively based on the method used to produce the posterior tibial slope. Group 1 used an extramedullary guide with a 0 degree cutting block tilted by placing 2 fingers between the tibia and the extramedullary guide proximally and three fingers between the tibia and guide distally to produce a 3 degree posterior slope (N=40). Group 2 used computer navigation (Stryker Navigation System, Stryker, Mahwah, NJ) to produce a 3 degree posterior slope (N=30). Group 3 used an extramedullary guide placed parallel to the anatomic axis of the tibia with a 5 degree cutting block to produce a 5 degree posterior slope (N=40). Posterior tibial slope was measured from lateral radiographs by 2 independent reviewers that were blinded to the treatment group. The reported posterior tibial slope for each sample was an average of these two measurements. Accuracy of the treatment group was evaluated using a one sample t test. Groups 1 and 2 were tested for an ideal slope of 3 degrees, and Group 3 was tested for an ideal slope of 5 degrees. An a priori sample size calculation with α=0.05 and β=0.20 showed that at least 24 samples in each treatment group were required to determine a difference of 1.5 degrees between the treatment group mean posterior tibial slope and the ideal posterior tibial slope.

Results: The mean posterior slope measurements for treatment Group 1 (4.15±3.24 degrees) and treatment Group 2 (1.60±1.62 degrees) were both significantly different than the ideal slope of 3 degrees (p=0.03 for Group 1 and p< 0.01 for Group 2). This indicates that treatment Groups 1 and 2 failed to accurately produce the ideal posterior tibial slope of 3 degrees. The mean posterior tibia slope of treatment Group 3 (5.00±2.87 degrees) was not significantly different than the ideal posterior tibial slope of 5 degrees (p=1.00). This indicates that Group 3 accurately produced the ideal tibial slope of 5 degrees.

Conclusion: The most accurate method to produce posterior tibial slope was the 5 degree cutting block with an extramedullary guide. Computer navigation had the lowest standard deviation and therefore was the most precise method. However, computer navigation was not as accurate in producing the desired posterior tibial slope as the extramedullary guide with the 5 degree cutting block. The manual method of producing tibial slope with an extramedullary guide and a 0 degree cutting block was the least precise method and not as accurate as the extramedullary guide with a 5 degree cutting block.

Purpose: Optimal fixation for comminuted proximal humerus fractures is controversial. Complications using locked plates have been addressed by anatomic reduction or medial cortical support. The current study measured relative mechanical contributions of varus malalignment and medial cortical support.

Method: Forty synthetic humeri were divided into three groups, osteotomized, and fixed at 0, 10, and 20 degrees of varus malreduction with locked proximal humerus plates (AxSOS, Global model, Stryker, Mahwah, NJ, USA). This simulated mechanical medial support with the cortex intact. Axial, torsional, and shear stiffness were experimentally measured. Half of the specimens in each of the groups underwent a second osteotomy to create a segmental defect which simulated loss of medial support with the cortex removed. Axial, torsional, and shear stiffness experiments were repeated, followed by shear load to failure in 20 degrees of abduction.

Results: For isolated malreduction with the cortex intact, the repair construct at 0 degrees showed statistically equivalent or higher axial, torsional, and shear stiffness than other groups assessed. Subsequent removal of cortical support in half the specimens resulted in a drastic effect on axial, torsional, and shear stiffness at all varus angles. Repair constructs with the cortex intact at 0 and 10 degrees resulted in mean shear failure forces of 12965.4 N and 9341.1 N, respectively. These were statistically higher (p< 0.05) compared to most other groups tested. Specimens failed mainly by plate bending as the femoral head was pushed down medially and distally.

Conclusion: Anatomic reduction with the medial cortex intact was the stiffest construct after a simulated two-part fracture. This study also supports the practice of achieving medial cortical support by fixing proximal humeral fractures in varus if necessary. This may be preferable to fixing the fracture in anatomic alignment when there is a medial fracture gap.

Purpose: The purpose of this study was to compare the effects of two types of stem/progenitor cells on the healing of critical sized bone defects in a rat model. Endothelial Progenitor Cells (EPCs), a novel cell type with previously demonstrated effects on angiogenesis in animal models of vascular disease, were compared to both a control group of no cell therapy, and a treatment group of Mesenchymal Stem Cells (MSCs). The hypothesis was that EPCs would demonstrate both superior bone healing and angiogenesis, when compared to the control group and MSC group.

Method: EPCs and MSCs were isolated from the bone marrow of syngeneic rats by differential culture and grown ex vivo for 10 days. Subsequently the cells were harvested, seeded on a gelfoam scaffold, and implanted into a 5mm segmental defect in a rat femur that had been stabilized with a plate and screws. Bone healing was assessed radiographically and by microCT. Angiogenesis was assessed by histology and physiologically, using laser doppler to assess blood flow in the bone and soft tissues. All animal protocols were approved by and performed in accordance with the St. Michael’s Hospital Animal Care Committee. ANOVA was used to test for significant differences between the groups, and a p-value of < 0.05 was considered statistically significant.

Results: The EPC (n=14) group demonstrated radiographic evidence of healing of the bone defect as early as 2 weeks, and all specimens were radiographically healed at 6 weeks. Both the control group (n=14) and the MSC group (n=14) showed no radiographic evidence of healing at 10 weeks. MicroCT comparison of the EPC group versus the control group showed significantly greater bone volume and density at the defect site (p< 0.001). More blood vessel formation was observed in the EPC group versus the control group on histology at 2 weeks. Laser Doppler assessment showed significantly more soft tissue and bone blood flow at 2 and 3 weeks in the EPC group versus the control group (p=0.021).

Conclusion: The results of this study demonstrate that EPCs are effective as cell-based therapy for healing critical sized bone defects in a rat model. In this model EPCs demonstrated superiority to MSCs with regard to bone healing. In addition, EPCs demonstrated superior angiogenesis over controls in a rat model of fracture healing. These results strongly suggest that EPCs are effective for therapeutic angiogenesis and osteogenesis in fracture healing. There is a clinical need for effective strategies in the management of traumatic bone defects and nonunions. Investigation into the use of MSCs as an effective alternative to autologous bone grafting has failed to translate into clinical use. It is possible that EPCs are more effective at the regeneration of bone in segmental defects because of their synergistic effect on angiogenesis and osteogenesis. Further research into EPC based therapies for fracture healing is warranted.

Purpose: Today, numerous functional outcome tools exist to assess the patient’s ability to carry out basic and instrumental activities of daily living. Furthermore, the increase in range of mobility measures reflect differences in rating scales, scores, administration and scoring options which make outcome results difficult to assess across trials. Because of the lack of consensus among investigators, we wanted to identify the citation patterns of the functional outcomes tools used by investigators in hip fracture RCTs. We believed that the lack of proper citation is an underlying factor in the diverse usage of outcome tools.

Method: We extracted the citations of disability tools from 59 Level 1 hip fracture RCTs. Disability was defined using the WHO classification (ICF). We excluded measures assessing body structure. The text and reference lists of the identified articles were screened in order to compile relevant literature on the instrument used in the RCT. Disability tools which were cited in the references were also compared to original development articles.

Results: Overall 68 different instruments were identified that measured disability in the hip fracture literature. According to ICF, 47 tools measured body function alone, 13 tools evaluated activity limitations and participation restriction and 8 were composite scoring systems. We found that 34.2% of the trials did not provide any citations to the tools assessing body function. In trials measuring activity and participation, 23.2% provided instrument citations. In trials using composite scoring systems, 19.4% of the trials provided instrument citations. All of the instrument citations when provided by the investigators were found to correspond to original development articles or trials.

Conclusion: The appropriate choice of a functional outcome instrument is fundamental in order to ensure that the results that are obtained reflect the patient. However, if citations of the indices and scales themselves are lacking, trial methodology and results could be informative but not replicated. In the future, we recommend that rigor in quality reporting include proper instrument citations.

Purpose: Severe fractures damage blood vessels and disrupt circulation at the fracture site resulting in an increased risk of poor fracture healing. Endothelial progenitor cells (EPCs) are bone-marrow derived cells with the ability to differentiate into endothelial cells and contribute to neovascularization and re-endothelialization after tissue injury and ischemia. We have previously reported that EPC therapy resulted in improved radiographic healing and histological blood vessel formation in a rat fracture model. The purpose of this study was to further quantify the effects of EPC therapy with microCT and biomechanical analyses.

Method: Five-millimeter segmental defects were created and stabilized in the femora of 14 fisher 344 rats. The treatment group (n=7) received 1x106 EPCs within gelfoam locally at the area of the bone defect and control animals (n=7) received only saline-gelfoam with no cells. The formation and healing of bone after 10 weeks were asessed by radiographic, micro-CT and biomechanical analyses.

Results: Radiographically all the animals in EPC-treated group healed with bridging callus formation, whereas control group animals demonstrated radiographic non-union. Micro-CT assessment demonstrated significantly improved parameters of bone volume (35.34 to 20.68 mm³, p=0.000), bone volume density (0.24 to 0.13%, p=0.001), connectivity density (25.13 to 6.15%, p=0.030), trabecular number (1.14 to 0.51 1/mm, p=0.000), trabecular thickness (0.21 to 0.26 mm, p=0.011), trabecular spacing (0.71 to 1.88 mm, p=0.002), bone surface area (335.85 to 159.43mm, p=0.000), and bone surface to bone volume ratio (9.43 to 7.82 1/mm, p=0.013) in the defect site for the EPC group versus the control group respectively. Biomechanical testing showed that the EPC treatment group had a significantly higher torsional strength compared with the control group (EPC=164.6±27.9 Nmm, Control=29.5±3.8 Nmm; p value = 0.000). Similarly, the EPC treated fractures demonstrated significantly higher torsional stiffness versus controls (EPC=30.3±5.0 Nmm/ deg, Control=0.9±0.1 Nmm/deg; p value = 0.000). When biomechanically compared to contralateral intact limbs, the EPC treated limbs had similar torsional stiffness (p=0.996), but significantly lower torsional strength (p=0.000) and smaller angle of twist (p=0.002).

Conclusion: These results suggest that local EPC therapy significantly enhances fracture healing in an animal model. The biomechanical results show that control animals develop a mechanically unstable non-union. In contrast, EPC therapy results in fracture healing that restores the biomechanical properties of the fractured bone closer to that of intact bone.

Purpose: Unbiased outcome assessment in orthopedic clinical trials has the potential to improve trial validity. The approaches used to limit bias in outcome assessment in orthopaedic trials remain unclear. The objective of this systematic review was to assess the reporting and process of outcomes assessment practices in the current orthopaedic trauma literature.

Method: We searched eight high-impact-factor medical and orthopaedic journals manually and using the MED-LINE electronic database for reports of randomized controlled trials published from 2005 to 2008 pertaining to the surgical treatment of trauma-related injuries. Two reviewers independently determined study eligibility and extracted relevant data from included trials.

Results: Of the 7910 citations identified during our search, 47 randomized controlled trials, which included a total of 4706 patients, met our inclusion criteria. Of 47 studies, 39 (83%) provided a statement to describe some process of outcome assessment and 29 (74%) reported using an unblinded individual as the outcome adjudicator. Four studies (10%) reported using a second assessor to verify outcome measurements, and three studies (8%) reported the use of an adjudication committee to reach endpoint decisions via consensus. No included study provided a rationale for the use of their chosen approach to adjudication. The most commonly adjudicated outcomes included fracture healing (15 studies), reoperation rate (6 studies), and general clinical assessment of post-operative complications and limb function (30 studies), mainly by orthopaedic surgeons. Blinding of outcome assessors was not performed or unclear in 38 studies (81%).

Conclusion: Despite the importance of the outcome assessment process in orthopedic trauma trials, key aspects of outcome assessment are insufficiently reported. This limits the ability of readers to assess the validity of published trials.

Purpose: Failure to adequately recruit patients in orthopaedic trials has often led to early stopping and publication of research findings from smaller sample sizes than originally planned. The purpose of this study is to demonstrate the effect of sample size in a large, clinical trial by using SPRINT trial data to evaluate the results that would have been reported if the trial were stopped at various enrollments.

Method: The SPRINT trial evaluated reamed vs. unreamed nailing in 1226 tibia fractures. We analyzed the re-operation rates after various increments in sample size and compared the early results that would have been reported at smaller enrollments with those seen in the final, adequately powered study.

Results: In the final analysis of 1226 patients, there was a significant reduction in the risk of re-operation with reamed nails for closed fractures (35% reduction; p=0.02) and a trend towards an increased risk of re-operation for open fractures (23% increase; p=0.26). In stark contradiction, the results for the first 50 patients enrolled in the trial revealed a substantial increased risk for reamed nails in closed fractures (risk increase: 165%). It was not until enrollment reached 800 patients that the results reflected the final findings of an advantage for reamed nails. In open fractures, the trend favoring unreamed nails was not seen until 200 patients had been enrolled.

Conclusion: Our findings suggest that stopping the SPRINT trial early would have led to misleading estimates of the treatment effect between reamed and unreamed nails.

Purpose: To determine the effect of reamed versus non-reamed intramedullary (IM) nailing of femoral diaphyseal fractures on the rates of non-union and acute respiratory distress syndrome (ARDS).

Method: We searched the online databases of OVID, MEDLINE, EMBASE, PubMed, and the Cochrane collaboration for randomized clinical trials (RCT) from 1998 to 2009. Additional studies were identified by hand searches of major orthopaedic journals, reference lists of eligible studies, SCISEARCH, and title reviews of presentations from major orthopaedic trauma meetings. Inclusion criteria were trials evaluating the effect of reamed versus nonreamed closed interlocked intra-medullary nailing of femoral diaphyseal fractures on the rates of nonunion or acute respiratory distress syndrome (ARDS) in skeletally mature adults. Exclusion criteria included patients with pathologic fractures, skeletally immature patients, as well as observational and other non-randomized studies.

Results: Seventy-two citations were initially identified out of 1,147 studies. 6 studies matched all eligibility criteria as assessed by three independent reviewers. A total of 941 patients with 956 femoral diaphyseal fractures treated with intramedullary nailing met the eligibility criteria. The relative risk of non-union (four trials, n= 456 patients) was 0.29 [95% confidence interval (CI), 0.14 to 0.57; p< 0.00001] (ie. a 70% relative risk reduction of nonunion) in favour of a reamed intramedullary nail There was no significant difference in the rates of ARDS following reamed or non-reamed nailing, relative risk for ARDS (two trials, n=397) 1.10 [95% CI, 0.27 to 4.54, p=0.18].

Conclusion: The study suggests that reamed intramedullary nailing of femoral diaphyseal fractures significantly reduces the risk of non-union as compared to nonreaming. The risk of ARDS was not statistically significant between groups; however there was a slight trend towards ARDS iwith reamed IM fixation.

Purpose: Minimizing tip-apex distance (TAD) has been shown to reduce clinical failure of extramedullary sliding hip screws used to fix peritrochanteric fractures. There is debate regarding the optimal position of the lag screw in the femoral head when a cephalomedullary nail is used to treat a peritrochanteric fracture. Some authors suggest the TAD should be minimized as with an extramedullary sliding hip screw, while others suggest the lag screw should be placed inferior within the femoral head. The primary goal of this study was to determine which of 5 possible lag screw positions in the femoral head provides greatest mechanical stiffness and/or load-to-failure for an unstable peritrochanteric fracture treated with a cepha-clomedullary nail. The secondary goal was to determine if there is a linear correlation between implant-femur mechanical stiffness and/or load to failure (dependent variables) with a series of five radiographic measurements (independent variables) of distance from the lag screw tip to the femoral head apex.

Method: Long Gamma 3 Nails (Stryker, Mahwah, NJ) were inserted into 30 left synthetic femurs (Pacific Research Laboratories, Vashon, WA). An unstable four-part fracture was created, anatomically reduced, and repaired using one of 5 lag screw placements in the femoral head:

superior (n=6),

All specimens were radiographed in the anterioposterior and lateral planes, and radiographic measurements including TAD and a calcar referenced tip-apex distance (CalTAD) were calculated. All specimens were tested for axial, lateral, and torsional stiffness, and then loaded-to-failure in the axial position using an Instron 8874 (Canton, MA). ANOVA was used to compare means of the five treatment groups. Linear regression analysis was used to compare stiffness and load-to-failure (dependant variables) with radiographic measurements (independent variables). A post hoc power analysis was performed.

Results: The inferior lag screw position had significantly greater mean axial stiffness than superior (p< 0.01), anterior (p=0.02) and posterior (p=0.04) positions. Analysis revealed significantly less mean torsional stiffness for the superior lag screw position compared to other lag screw positions (p< 0.01 all 4 pairings). No statistical differences were noted for lateral stiffness. Superior and central lag screw positions had significantly greater mean load-to-failure than anterior (p< 0.01 and p=0.02) and posterior (p< 0.01 and p=0.05) positions.

There were significant negative linear correlations between stiffness tests with CalTAD, and load-to-failure with TAD. Power was greater than 95% for axial stiffness, torsional stiffness and load-to-failure tests.

Conclusion: Position of the lag screw in the femoral head affects the biomechanical properties of the implant-femur construct. Central placement of the lag screw with minimization of TAD may provide the best combination of stiffness and load-to-failure.

Purpose: Cephalomedullary nails rely on a large lag screw that provides fixation into the femoral head. There is an option to statically lock the lag screw (static mode) or to allow the lag screw to move within the nail to compress the intertrochanteric fracture (dynamic mode). The purpose of this study was to compare the biomechanical stiffness of static and dynamic modes for a cephalomedullary nail used to fix an unstable peritrochanteric fracture.

Method: Thirty intact synthetic femur specimens (Model #3406, Pacific Research Laboratories, Vashon, WA) were potted into cement blocks distally for testing on an Instron 8874 (Instron, Canton, MA). A long cephalomedullary nail (Long Gamma 3 Nail, Stryker, Mahwah, NJ) was then inserted into each of the femurs. An unstable four-part fracture was created, anatomically reduced, and the cephallomedullary nail was reinserted. Mechanical tests were conducted for axial, lateral, and torsional stiffness with the lag screws in:

static and

A paired student’s t test was used to compare the 2 modes.

Results: The axial stiffness of the cephalomedullary nail was significantly greater (p< 0.01) in the static mode (484.3±80.2N/mm) than in the dynamic mode (424.1±78.0N/mm) (Fig.2A). Similarly, the lateral bending stiffness of the nail was significantly greater (p< 0.01) in the static mode (113.9±8.4N/mm) than in the dynamic mode (109.5±8.8N/mm). The torsional stiffness of the nail was significantly greater (p=0.02) in the dynamic mode (114.5±28.2N/mm) than in the static mode (111.7±27.0N/mm).

A post hoc power analysis with & #945;=0.05 and & #946;=0.20 revealed that the paired t test on 30 samples was sufficiently powered to determine a difference in mean axial stiffness of 33.0N/mm (6.8% of static stiffness), a difference in mean lateral bending stiffness of 3.6N/mm (3.2% of static stiffness) and a difference in mean torsional stiffness of 3.4N/mm (3.0% of static stiffness).

Conclusion: Our results show that there is a 60N/mm reduction in axial stiffness of the cephalomedullary nail when the lag screw is changed from static to dynamic mode. This represents a 12.4% reduction in axial stiffness with a change from axial to dynamic modes which may be clinically significant. The differences in lateral (4.4N/mm, 3.9%) and torsional (2.8N/mm, 2.4%) are small enough that they are likely not clinically significant. We felt that a difference of greater than 10% in axial stiffness and a difference of greater than 5% in lateral or torsional stiffness would be clinically significant. Our study was adequately powered to detect these differences. Given the significant reduction in axial stiffness with dynamization of the cephalomedullary nail construct, we recommend use of the static mode when treating unstable peritrochanteric fractures with a cephalomedullary nail.

Purpose: Preoperative planning forces the surgeon to understand the “fracture personality” and devise an operative plan. In our experience, trainees have difficulty in preparing for complex acetabular cases; these fractures are among the most difficult fractures to conceptualize and teach. As a result, these fractures are poorly understood as demonstrated by low interobserver agreement between trainees in the classification of acetabular fractures. We sought to determine whether the use of visou-haptic technology would help trainees to appreciate the “personality” of an Associated-Both-Column (ABC)fracture more accurately than trainees taught by conventional instruction.

Method: Thirty senior medical students and PGY1 residents, were randomized into two groups. The control group studied an ABC fracture with the aid of a textbook excerpt and a 3D CT reconstruction of the fracture. The intervention group was given the same instructional materials, and a visuo-haptic CT model of the fracture. All other learning variables, including time on task were standardized. Participants were evaluated on their accuracy in drawing the fracture lines on a model pelvis.

Results: There was no significant difference in gender, visuo-spatial ability, and training level between groups. The participants taught with the visuo-haptic model recalled an additional 26% anatomic relationships (p< 0.01) compared with the control group.

Conclusion: These findings suggest that in addition to the benefits observed in the learning of motor skills, visuo-haptic input may improve the understanding of spatial relationships. This technology may be a useful adjunct for teaching anatomy, as well as preoperative planning.

Purpose: Accurate prediction of re-operation following tibial nailing may facilitate optimal patient care. We recently completed the SPRINT trial, a large, multi-centre trial of reamed versus non-reamed intramedullary nails in 1226 patients with tibial shaft fractures. Using the SPRINT data, we conducted an investigation of baseline and surgical patient characteristics to determine if they are associated with increased risk of re-operation within one year.

Method: Using multivariable logistic regression analysis, we investigated 15 characteristics for association with increased risk of re-operations. Because the primary SPRINT analysis found that reamed nailing reduced events in patients with closed but not open fractures, we considered both open and closed as well as treatment status in our model.

Results: We found an increased risk of re-operation in patients with a high energy mechanism of injury (odds ratio, OR=1.57, 95% CI 1.05 to 2.35), stainless steel versus titanium nail (OR=1.52, 95% CI 1.10 to 2.13), fracture gap (OR=2.40, 95% CI 1.47 to 3.94) and post-operative weightbearing (OR=1.63, 95% 1.003 to 2.64). Open fractures increased the risk of re-operation in patients who received a reamed nail (OR=3.26, 95% CI 2.01 to 5.28) but not in patients who received a non-reamed nail (OR=1.50, 95% CI 0.92 to 2.47). Patients with open fractures who had either wound management without any additional procedures, or delayed primary closure, had a decreased risk of re-operation when compared to patients who required subsequent reconstruction (respectively, OR=0.18, 95% CI 0.09 to 0.35; OR=0.29 95% CI 0.14 to 0.62).

Conclusion: To ensure optimal patient care surgeons should consider the characteristics identified in our analysis to reduce risk of re-operation.

Purpose: The use of UHMW polyethylene acetabular liners is known to cause polyethylene wear related osteolysis, the major limiting factor in its use in the younger active patient. Modern alumina ceramic articulations have been developed in order to reduce wear and avoid polyethylene debris. This prospective randomized long-term study aims to compare the outcome between an alumina ceramic-on-ceramic (CC) articulation with a ceramic on UHMW polyethylene articulation (CP).

Method: Fixty-six hips in 55 patients with mean age 42.2 (range 19–56) each received uncemented components (Wright Medical) and a 28mm alumina head with acetabular liner selected via sealed envelope randomization following anesthetic induction. Subsequent regular clinical and radiologic follow up measured patient outcome scores and noted any radiological changes.

Results: Twenty-six CP hips and 30 CC hips were evaluated. One failure required revision in each group. Mean St Michael’s outcome score for each group with up to 10 years follow-up (median 8 years, range 1–10) was 22.8 and 22.9 respectively (p=0.057). Radiographs with a minimum 5 years post-operative follow-up were analyzed in 42 hips (23 CC and 19 CP). The mean time of wear measurement for the CC group was 8.3 years (SD 1.3, Range 4.8–10.1 years) and for the CP group was 8.1 years (SD 0.9, Range 6.1–9.2 years)(p=0.471). Wear was identified in all but one CP hip but in only 12 of 23 CC replacements. Mean wear in the CP group was 0.11mm per year and 0.02mm per year in the CC group (p< 0.001).

Conclusion: To our knowledge this is the first long term randomized trial comparing in-vivo ceramic-on-ceramic with ceramic-on-polyethylene hip articulations. Other than significantly greater wear in the polyethylene group there was no significant difference in long-term outcome scores between the two groups with up to 10 years of follow-up. The use of a ceramic-on-ceramic bearing is a safe and durable option in the young patient avoiding the concerns of active metal ions and osteolytic polyethylene debris.

Purpose: Vascular Endothelial Growth Factor (VEGF) plays an important role in promoting angiogenesis and osteogenesis during fracture repair. Our previous studies have shown that cell-based VEGF gene therapy accelerates bone healing of a rabbit tibia segmental bone defect in-vivo, and increases osteoblast proliferation and mineralization in-vitro. The aim of this project was to examine the effect of exogenous human VEGF (hVEGF) on the endogenous rat VEGF messenger RNA (mRNA) expression in a cell-based gene transfer model.

Method: The osteoblasts were obtained from the rat periosteum. The fibroblasts were obtained from the rat dermal tissue. The cells were then cultured to reach 60% confluence and transfected with hVEGF using Superfect. Four groups were:

osteoblast-hVEGF,

The cultured cells were harvested at 1, 3 and 7 days after the transfection. The total mRNA was extracted (TRIZOL); both hVEGF and rat VEGF mRNA were measured by reverse transcriptase-polymerase chain reaction (RT-PCR) and quantified by VisionWorksLS.

Results: The hVEGF mRNA was detected by RT-PCR from transfected osteoblasts after three days of gene transfection. The hVEGF mRNA expression in transfected fibroblasts increased exponentially at days 1, 3 and 7 after the transfection. We compared the endogenous rat VEGF mRNA expression level of the osteoblasts or fibroblasts that were transfected with hVEGF with the cells without the transfection. The hVEGF transfected osteoblasts had a greater rat VEGF mRNA expression than the non-transfected osteoblasts. Furthermore, when hVEGF was transfected to the rat fibroblasts, the endogenous mRNA expression level measured was also greater than that from the non-transfected fibroblasts. Rat VEGF mRNA expression increased in the first three days of the hVEGF transfection, but the expression level was reduced at Day 7.

Conclusion: These results suggest that cell-based hVEGF gene therapy enhances endogenous rat VEGF mRNA expression in both osteoblasts and fibroblasts.

Purpose: The purpose of this study was to relate the extent of reaming to bone formation occurring around a critical sized defect in the tibia.

Method: Eleven canines were allocated into 2 groups: empty (N=5) or iliac crest autograft (N=6). All tibiae were reamed to 7.0 mm and fixed with a 6.5 mm statically locked intramedullary nail after creation of an 8.0 mm diaphyseal defect. The extent of reaming of the canal was dependent on the cross-sectional area of the tibia as all tibiae were reamed to 7.0 mm. Fluorescent markers were given at different times: calcein green (6 weeks), xylenol orange (9 weeks), and tetracycline (11 and 14 weeks). Animals were sacrificed at 15 weeks and perfused with a barium compound. Radiography, Micro CT, brightfield microscopy and fluorescent microscopy were used for analysis.

Results: Bone and vasculature volume within the defect were reported as a percentage of the total volume of the defect. Linear regression analysis of percent bone volume (dependent variable) and canal area (independent variable) provided a Pearson correlation coefficient of 0.925 (p=0.025) for the empty group and 0.244 (p=0.641) for the autograft group. Linear regression analysis of percent vasculature volume (dependent variable) and canal area (independent variable) provided a Pearson correlation coefficient of 0.784 (p=0.117) for the empty group and −0.146 (p=0.783) for the autograft group. Bone formation at osteotomy sites was defined as the distance from the original osteotomy site to the tip of newly formed bone. Linear regression analysis of bone formation at the osteotomy sites (dependent variable) and canal area (independent variable) provided a Pearson correlation coefficient of 0.132 (p=0.832) for the empty group and −0.937 (p=0.006) for the autograft group. Bone formation rates were reported as the distance between the fluorescent labels. Bone formation rate was less within the endosteum, cortex and periosteum with extensive reaming in empty samples.

Conclusion: Our results suggest that the acute management of tibia fractures with bone defects should involve limited reaming. This does not apply when the defect is autografted. Limited reaming may be defined by the cross-sectional area of the tibia in ratio to that of the reamer.