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Chlorhexidine skin antisepsis is frequently recommended for most surgical procedures; however, it is unclear if these recommendations should apply to surgery involving traumatic contaminated wounds where povidone-iodine has previously been preferred. We aimed to compare the effect of aqueous 10% povidone-iodine versus aqueous 4% chlorhexidine gluconate on the risk of surgical site infection in patients who required surgery for an open fracture.We conducted a multiple-period, cluster-randomised, crossover trial (Aqueous-PREP) at 14 hospitals in Canada, Spain, and the USA. Eligible patients were adults aged 18 years or older with an open extremity fracture treated with a surgical fixation implant. For inclusion, the open fracture required formal surgical debridement within 72 h of the injury. Participating sites were randomly assigned (1:1) to use either aqueous 10% povidone-iodine or aqueous 4% chlorhexidine gluconate immediately before surgical incision; sites then alternated between the study interventions every 2 months. Participants, health-care providers, and study personnel were aware of the treatment assignment due to the colour of the solutions. The outcome adjudicators and data analysts were masked to treatment allocation. The primary outcome was surgical site infection, guided by the 2017 US Centers for Disease Control and Prevention National Healthcare Safety Network reporting criteria, which included superficial incisional infection within 30 days or deep incisional or organ space infection within 90 days of surgery. The primary analyses followed the intention-to-treat principle and included all participants in the groups to which they were randomly assigned. This study is registered with ClinicalTrials.gov, NCT03385304.Between April 8, 2018, and June 8, 2021, 3619 patients were assessed for eligibility and 1683 were enrolled and randomly assigned to povidone-iodine (n=847) or chlorhexidine gluconate (n=836). The trial's adjudication committee determined that 45 participants were ineligible, leaving 1638 participants in the primary analysis, with 828 in the povidone-iodine group and 810 in the chlorhexidine gluconate group (mean age 44·9 years [SD 18·0]; 629 [38%] were female and 1009 [62%] were male). Among 1571 participants in whom the primary outcome was known, a surgical site infection occurred in 59 (7%) of 787 participants in the povidone-iodine group and 58 (7%) of 784 in the chlorhexidine gluconate group (odds ratio 1·11, 95% CI 0·74 to 1·65; p=0·61; risk difference 0·6%, 95% CI -1·4 to 3·4).For patients who require surgical fixation of an open fracture, either aqueous 10% povidone-iodine or aqueous 4% chlorhexidine gluconate can be selected for skin antisepsis on the basis of solution availability, patient contraindications, or product cost. These findings might also have implications for antisepsis of other traumatic wounds.US Department of Defense, Canadian Institutes of Health Research, McMaster University Surgical Associates, PSI Foundation.

Author(s): Pogorzelski, David; Nguyen, Uyen; McKay, Paula; Thabane, Lehana; Camara, Megan; Ramsey, Lolita; Seymour, Rachel; Goodman, J Brett; McGee, Sheketha; Fraifogl, Joanne; Hudgins, Andrea; Tanner, Stephanie L; Bhandari, Mohit; Slobogean, Gerard P; Sprague, Sheila; PREP-IT Investigators Executive Committee:; Steering Committee; Adjudication Committee; Data and Safety Monitoring Committee; Research Methodology Core; Patient Centred Outcomes Core; Orthopaedic Surgery Core; Operating Room Core; Infectious Disease Core; Military Core; McMaster University Methods Center; University of Maryland School of Medicine Administrative Center; University of Maryland School of Pharmacy, The PATIENTS Program; PREP-IT Clinical Sites: Lead Clinical Site (Aqueous-PREP and PREPARE); Aqueous-PREP and PREPARE; Aqueous-PREP; PREPARE; PREP-IT Investigators Executive Committee | Abstract: IntroductionPragmatic trials in comparative effectiveness research assess the effects of different treatment, therapeutic, or healthcare options in clinical practice. They are characterized by broad eligibility criteria and large sample sizes, which can lead to an unmanageable number of participants, increasing the risk of bias and affecting the integrity of the trial. We describe the development of a sampling strategy tool and its use in the PREPARE trial to circumvent the challenge of unmanageable work flow.MethodsGiven the broad eligibility criteria and high fracture volume at participating clinical sites in the PREPARE trial, a pragmatic sampling strategy was needed. Using data from PREPARE, descriptive statistics were used to describe the use of the sampling strategy across clinical sites. A Chi-square test was performed to explore whether use of the sampling strategy was associated with a reduction in the number of missed eligible patients.Results7 of 20 clinical sites (35%) elected to adopt a sampling strategy. There were 1539 patients excluded due to the use of the sampling strategy, which represents 30% of all excluded patients and 20% of all patients screened for participation. Use of the sampling strategy was associated with lower odds of missed eligible patients (297/4545 (6.5%) versus 341/3200 (10.7%) p l 0.001).ConclusionsImplementing a sampling strategy in the PREPARE trial has helped to limit the number of missed eligible patients. This sampling strategy represents a simple, easy to use tool for managing work flow at clinical sites and maintaining the integrity of a large trial.

Pelvic positioning during total hip arthroplasty (THA) affects functional position of the acetabular component. We sought to evaluate whether preoperative pelvic tilt correlated with intraoperative pelvic tilt while positioned on a traction table for direct anterior THA and furthermore to evaluate whether there was a consistent and predictable effect on pelvic tilt while positioned for surgery.We evaluated the sagittal spinopelvic preoperative standing and supine pelvic tilt radiographic measurements as compared with intraoperative measurements of 25 patients. Changes in pelvic tilt were analyzed for statistical significance and interobserver reliability.The mean standing pelvic tilt was 13.5° ± 5.7°. The mean supine pelvic tilt was 13.3° ± 6.1°. There was no statistically significant difference between standing and supine pelvic tilt (P = .866). The mean intraoperative pelvic tilt was 3.0° ± 6.2°. There was a statistically significant decrease in pelvic tilt between both standing to intraoperative comparison and supine to intraoperative comparison (P.0001 for both). Difference in mean between these comparisons was 10.5° ± 4.6° (95% confidence interval, 8.7°-12.3°) and 10.3° ± 6.3° (95% confidence interval, 7.8°-12.8°), respectively.Patient positioning on a traction table for direct anterior THA has a reliable effect on pelvic tilt in the magnitude of approximately 10° decreased pelvic tilt. This effect on pelvic tilt correlates to approximately 7.4° and 3° altered anteversion and inclination, respectively. Taking into account this change in pelvic tilt at the time of surgery will allow the hip arthroplasty surgeon to more accurately place acetabular components in the desired functional position.

Two complete unicondylar surface replacement scaffold designs to support tissue-engineered cartilage growth that utilized adult endogenous stem cells were 3D printed and tested in a dog stifle model. Integrated rosette strain gauges were calibrated and used to determine shear loading within stifle joints for up to 12 months. An activity index that compared extent of daily activity with tissue formation showed differences in the extent and quality of new tissue with the most active animal having the most new tissue formation. Shear loads were highest early and decreased with time indicating that cartilage tissue formation begins while tissues experience high shear loads and continues as the loads decrease toward normal physiological levels. Scaffolds with biomimetic support pegs facilitated the most rapid bone ingrowth and were noted to have more cartilage formation with better quality cartilage as measured using both indentation testing and histology. Comparison of implant placement depth to previous studies suggested that placement depth affects the amount of tissue formation. This study provides measurements of loading patterns and cartilage regeneration on a complete medial condylar surface replacement that can be used for preclinical testing of a tissue engineering approach for the most common form of early stage osteoarthritis, unicondylar disease. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1409-1421, 2017.

Recent interest in repair of chondral and osteochondral cartilage defects to prevent osteoarthritis caused by ligament disruption has led to the research and development of biomimetic scaffolds combined with cell-based regeneration techniques. Current clinical focal defect repair strategies have had limited success. New scaffold-based approaches may provide solutions that can repair extensive damage and prevent osteoarthritis. This study utilized a novel scaffold design that accommodated strain gauges for shear and axial load monitoring in the canine stifle joint through implantable telemetry technology. Loading changes induced by ligament disruption are widely implicated in the development of injury-related osteoarthritis. Seeding the scaffold end with progenitor cells resulted in higher shear stress than without cell seeding and histology showed significantly more bone and cartilage formation. Biomechanically, the effect of transecting the anterior cruciate ligament was a significant reduction in braking load in shear, but no change axially, and conversely a significant reduction in push-off load axially, but no change in shear. This is the first study to report shear loads measured directly in knee joint tissue. Further, advances of these measurement techniques are critical to developing improved regeneration strategies and personalizing reliable rehabilitation protocols.

Background: Pediatric supracondylar humerus fractures are the most common elbow fractures in children. Operative management includes closed reduction and placement of 2 to 3 laterally based pins. Occasionally, a medial pin is used to create a crossed fixation pattern, despite risk of nearly 10% iatrogenic ulnar nerve injury. The objective of this study was to assess the trends and outcomes in the operative management of pediatric supracondylar humerus fractures at a level one academic trauma center. Materials & Methods: A retrospective review was performed on all children sustaining a Gartland type II or III supracondylar humerus fractures treated by closed or open reduction and percutaneous pinning in 2006-2008 and 2009-2011 at a level one academic trauma center by two of the authors (JTR, LMT). Pin placement patterns were evaluated and compared based on year performed. Outcomes measured were rates of ulnar nerve symptoms, non-union, re-operation, and varus malalignment. Data analysis was performed using a Fisher exact test on STATA software. Results: A total of 49 patients met inclusion criteria. Of 22 patients treated in 2006-2008, 5 (23%) were type II and 17 (77%) were type III. From 2009-2011, 16 (59%) were type II and 11 (41%) were type III. Comparison of pinning pattern in type II fractures between 2006-2008 and 2009-2011 did not indicate statistical significance (p = 0.429). Comparison of pinning pattern in type III fractures during the same time period did show that there was a statistically significant decrease (p = 0.010) in the number of cross pin fixations. There were no ulnar nerve injuries, non-unions, re-operations, or varus malalignment in any patient on final follow-up. Conclusion: This study shows that there has been a significant decrease in cross pin fixation for pediatric type III supracondylar humerus fractures with equivalent clinical outcomes at a Level I trauma center. Furthermore, performing lateral pinning for type III fractures has eliminated the risk of iatrogenic ulnar nerve injury. Level of Evidence: Level III—Retrospective cohort study.

Injuries sustained by unauthorized individuals who jump or fall from the United States–Mexico border fence are frequently treated by trauma centers in border states. The authors investigated patterns of musculoskeletal injury occurring in these individuals to improve emergency department assessment and to identify strategies to prevent future injuries. A retrospective chart review was performed for patients presenting to an urban, level I trauma center with musculoskeletal injuries sustained in a jump or fall from the United States–Mexico border fence between February 2004 and February 2010. Frequency of fracture by site, frequency of open fracture, and associated patterns of injury were recorded. The population was stratified by age and sex to identify disparity in injury pattern. Average length of stay and number of surgical interventions were also recorded. During the study period, 174 individuals who had jumped or fallen from the United States–Mexico border fence were identified. The population contained 93 (53%) women and 81 (47%) men with an average age of 31.5 years (range, 11–56 years). On average (±standard error), men sustained slightly more fractures than women (1.77±0.12 vs 1.43±0.07; P =.015). There were no significant differences in the number of fractures sustained between age groups. Average length of stay for patients admitted to the hospital was 3.5 days. Patients underwent an average of 0.75 surgical interventions during admission. Falls from the United States–Mexico border fence are a significant cause of morbidity among unauthorized immigrants. [ Orthopedics. 2017; 40(3):e432–e435.]

There has been recent interest in treating large bone defects with polymer scaffolds because current modalities such as autographs and allographs have limitations. Additionally, polymer scaffolds are utilized in tissue engineering applications to implant and anchor tissues in place, promoting integration with surrounding native tissue. In both applications, rapid and increased bone growth is crucial to the success of the implant. Recent studies have shown that mimicking native bone tissue morphology leads to increased osteoblastic phenotype and more rapid mineralization. The purpose of this study was to compare bone ingrowth into polymer scaffolds created with a biomimetic porous architecture to those with a simple porous design. The biomimetic architecture was designed from the inverse structure of native trabecular bone and manufactured using solid free form fabrication. Histology and muCT analysis demonstrated a 500-600% increase in bone growth into and adjacent to the biomimetic scaffold at five months post-op. This is in agreement with previous studies in which biomimetic approaches accelerated bone formation. It also supports the applicability of polymer scaffolds for the treatment of large tissue defects when implanting tissue-engineering constructs. (c) 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009.

Fractures of the distal humerus involving the articular surface can be challenging. The complexity of these fracture patterns increases when the distal fracture is associated with a concomitant humeral shaft fracture with significant proximal extension. The combined exposure technique described here allows for consistent and controlled posterior humeral exposure proximally from the traverse of the axillary nerve to the distal trochlear tip. It is especially useful for complex segmental fracture patterns where distal intra-articular involvement is present and a single approach is desired.

Two complete unicondylar surface replacement scaffold designs to support tissue-engineered cartilage growth that utilized adult endogenous stem cells were 3D printed and tested in a dog stifle model. Integrated rosette strain gauges were calibrated and used to determine shear loading within stifle joints for up to 12 months. An activity index that compared extent of daily activity with tissue formation showed differences in the extent and quality of new tissue with the most active animal having the most new tissue formation. Shear loads were highest early and decreased with time indicating that cartilage tissue formation begins while tissues experience high shear loads and continues as the loads decrease toward normal physiological levels. Scaffolds with biomimetic support pegs facilitated the most rapid bone ingrowth and were noted to have more cartilage formation with better quality cartilage as measured using both indentation testing and histology. Comparison of implant placement depth to previous studies suggested that placement depth affects the amount of tissue formation. This study provides measurements of loading patterns and cartilage regeneration on a complete medial condylar surface replacement that can be used for preclinical testing of a tissue engineering approach for the most common form of early stage osteoarthritis, unicondylar disease. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1409-1421, 2017.

No technique has been consistently successful in the repair of large focal defects in cartilage, particularly in older patients. Tissue-engineered cartilage grown on synthetic scaffolds with appropriate mechanical properties will provide an implant, which could be used to treat this problem. A means of monitoring loads and pressures acting on cartilage, at the defect site, will provide information needed to understand integration and survival of engineered tissues. It will also provide a means of evaluating rehabilitation protocols. A “sensate” scaffold with calibrated strain sensors attached to its surface, combined with a subminiature radio transmitter, was developed and utilized to measure loads and pressures during gait. In an animal study utilizing six dogs, peak loads of 120N and peak pressures of 11 MPa were measured during relaxed gait. Ingrowth into the scaffold characterized after 6 months in vivo indicated that it was well anchored and bone formation was continuing. Cartilage tissue formation was noted at the edges of the defect at the joint–scaffold interfaces. This suggested that native cartilage integration in future formulations of this scaffold configured with engineered cartilage will be a possibility.

Background: The most biomechanically stable relationship between the side plate of a compression hip screw (CHS) and retrograde intramedullary (IM) femoral nail has not been described in the literature. This becomes a clinical issue when treating supracondylar femur fractures with a retrograde nail in patients with a history of compression hip screw fixation of intertrochanteric fractures. The proximal end of the nail and the interlocking screws may act as a stress riser in the femoral diaphysis. The purpose of this study is to determine the biomechanical consequences of the amount of implant overlap between a CHS plate and retrograde IM femoral nail. Methods: Nine paired fresh-frozen cadaver femora from elderly donors were cleaned of soft tissue and fixed with uniaxial strain gauges. Each femur was loaded three times in a fall-loading configuration to 50 kg at a rate of 1 Hz. The study consisted of two phases. In phase 1, six pair were randomly divided into a control and test femur from each pair. Three states were compared on each test femur: uninstrumented, instrumented with CHS, and instrumented with CHS and retrograde nail. The control femur consisted of the matched femur tested in two states: uninstrumented and instrumented with a CHS. The femora were then loaded to failure. The tests were performed with the retrograde nail and CHS gapped 3 cm, kissing, and overlapping by two screw holes (two pair for each state). In phase 2, each of the remaining three pair were instrumented with a CHS and retrograde nail overlapping in one femur and gapped in the matched femur and tested in the same manner. Data analysis was performed using Pearson's correlation coefficients between groups. Paired samples t tests were used to compare differences within test states and independent samples t tests were used to compare differences between femora. Mean strain at 50-kg load, load-versus-strain patterns, failure patterns, and load and strain at failure were recorded. Results: Correlation coefficients were greater than 0.98 within and between pairs (p < 0.001). There were statistically significant differences (p < 0.05) in strain patterns between the uninstrumented, CHS, and CHS/IM test states. The addition of a side plate significantly (p < 0.05) increased lateral compressive strains in the femoral diaphysis. Mean strain at 50-kg load was significantly (p < 0.05) altered by the addition of the retrograde nail in all three implant orientations. Gapped implants failed at lower loads and strains than femurs with kissing and overlapping implants. Gapped constructs failed at lower loads than control states. Overlapped constructs tolerated the highest loads and strains before failure. Conclusion: Strain patterns are altered by the degree of implant overlap in the proximal femoral diaphysis. Femora with uninstrumented intervals between retrograde nails and side plates fail at lower loads than femora without retrograde nails and those with kissing or overlapping implants. Kissing or overlapping instrumentation increases load to failure and creates a more biomechanically stable construct than gapped implants. The findings of this study suggest an overlapping implant orientation in the femur increases failure load at the implant interface.

We present a 19-year-old collegiate athlete who sustained a low-energy closed tibial shaft fracture. Following closed reduction, the dorsalis pedis and posterior tibial pulses were symmetric to the contralateral limb on physical examination. Angiography later confirmed triple vessel arterial disruption complicated by delayed ischemia requiring limb revascularization. Lower extremity triple vessel occlusion from a low-energy injury is rare, and delayed presentation requiring limb salvage is even more unusual. We review the literature, describe the diagnosis and treatment, and propose a strategy for post-fracture reduction management of vascular status.

Recent interest in repair of chondral and osteochondral cartilage defects to prevent osteoarthritis caused by ligament disruption has led to the research and development of biomimetic scaffolds combined with cell-based regeneration techniques. Current clinical focal defect repair strategies have had limited success. New scaffold-based approaches may provide solutions that can repair extensive damage and prevent osteoarthritis. This study utilized a novel scaffold design that accommodated strain gauges for shear and axial load monitoring in the canine stifle joint through implantable telemetry technology. Loading changes induced by ligament disruption are widely implicated in the development of injury-related osteoarthritis. Seeding the scaffold end with progenitor cells resulted in higher shear stress than without cell seeding and histology showed significantly more bone and cartilage formation. Biomechanically, the effect of transecting the anterior cruciate ligament was a significant reduction in braking load in shear, but no change axially, and conversely a significant reduction in push-off load axially, but no change in shear. This is the first study to report shear loads measured directly in knee joint tissue. Further, advances of these measurement techniques are critical to developing improved regeneration strategies and personalizing reliable rehabilitation protocols.

Fifty-one capitellocondylar elbow replacements were inserted in forty-one patients between 1976 and 1986. Thirty-nine patients had rheumatoid arthritis and two had traumatic osteoarthrosis. The average age of the patients at the time of the operation was fifty-six years (range, twenty-one to seventy-seven years). Thirty-one patients who had thirty-nine retained elbow prostheses had an average length of follow-up of 6.5 years (range, two to thirteen years). Flexion improved an average of 20 degrees; extension, 4 degrees; pronation, 22 degrees; and supination, 36 degrees. Relief of pain was complete in 85 per cent of the thirty-nine elbows, and in 15 per cent there was only mild pain. Noteworthy postoperative complications in the original fifty-one elbows included infection in four elbows (8 per cent), dislocation in three (6 per cent), and ulnar neuropathy in sixteen (31 per cent). Three elbows were revised: one for a humeral fracture, one for recurrent dislocation, and one for aseptic loosening. Aseptic loosening was evident on radiographs of two elbows; one patient was completely asymptomatic, and one had mild pain with deformity. The Souter zonal radiographic assessment system for identification of radiolucencies at the bone-cement interface was utilized; there was no significant difference in radiolucencies between ulnar components backed with metal and those that were not backed with metal. Kaplan-Meier cumulative survivorship analysis demonstrated that a functional prosthesis was retained in 88 per cent of the elbows at 1.4 years postoperatively and in 83 per cent at 5.5 years.(ABSTRACT TRUNCATED AT 250 WORDS)

Polymer scaffolds have been used as a tool to provide growth and integration of engineered tissue substrates to repair damaged tissues in many organ systems including articular cartilage. Previous work has shown that "sensate" scaffolds, with integrated strain gauges have the potential for use as both a delivery vehicle for engineered cartilage as well as a device that can measure real time, in vivo joint loading. The purpose of this study was to use an implanted subminiature telemetry system to collect in vivo joint loading measurements over an extended period following placement of a "sensate" scaffold. Measurements were collected from seven of nine sensors that were implanted into the stifles of three canines. The limb loading rates and load distribution through gait were dependent on stride time but did not vary with time post op. The peak loads were not dependent on stride time but significantly increased with time post op. This demonstrated that peak loading measured with "sensate" scaffolds can be used to monitor healing. The portability of the "sensate" scaffolds coupled to telemetry systems highlights the potential use of this system in a clinical research setting to gather important information to improve tissue engineering and rehabilitation regimens.

Purpose. The adequacy of end-of-procedure free cefazolin concentrations after administration for the prevention of surgical-site infection (SSI) and compliance with national guidelines for antimicrobial prophylaxis for SSI were assessed. Methods. Patients undergoing elective surgery and receiving cefazolin for perioperative antimicrobial prophylaxis were prospectively enrolled. Antibiotic administration was controlled by the surgeon and usage was recorded. For each patient, a single blood sample for cefazolin serum free and total concentrations was obtained within 15 minutes of wound closure. A free serum concentration threshold of 4 μg/mL was arbitrarily chosen based on the minimum inhibitory concentration required to inhibit 90% of strains of methicillin-susceptible Staphylococcus aureus and Escherichia coli . Results. Fifty-seven subjects were enrolled, and noncompliance with published guidelines was observed for 26% of patients. Forty-six subjects had serum samples available for assay, 21.7% of whom had end-of-procedure free cefazolin concentrations of

Treatment of cartilage defects is essential to the prevention of osteoarthritis. Scaffold-based cartilage tissue engineering shows promise as a viable technique to treat focal defects. Added functionality can be achieved by incorporating strain gauges into scaffolds, thereby providing a real-time diagnostic measurement of joint loading. Strain-gauged scaffolds were placed into the medial femoral condyles of 14 adult canine knees and benchtop tested. Loads between 75 and 130 N were applied to the stifle joints at 30 degrees, 50 degrees, and 70 degrees of flexion. Strain-gauged scaffolds were able to reliably assess joint loading at all applied flexion angles and loads. Pressure sensitive films were used to determine joint surface pressures during loading and to assess the effect of scaffold placement on joint pressures. A comparison of peak pressures in control knees and joints with implanted scaffolds, as well as a comparison of pressures before and after scaffold placement, showed that strain-gauged scaffold implantation did not significantly alter joint pressures. Future studies could possibly use strain-gauged scaffolds to clinically establish normal joint loads and to determine loads that are damaging to both healthy and tissue-engineered cartilage. Strain-gauged scaffolds may significantly aid the development of a functional engineered cartilage tissue substitute as well as provide insight into the native environment of cartilage.

The basic goal of fracture fixation is to stabilize the fractured bone, to enable fast healing of the injured bone, and to return early mobility and full function of the injured extremity. Fractures can be treated conservatively or with external and internal fixation. Conservative fracture treatment consists of closed reduction to restore the bone alignment. Subsequent stabilization is then achieved with traction or external splinting by slings, splints, or casts. Braces are used to limit range of motion of a joint. External fixators provide fracture fixation based on the principle of splinting. There are three basic types of external fixators: standard uniplanar fixator, ring fixator, and hybrid fixator. The numerous devices used for internal fixation are roughly divided into a few major categories: wires, pins and screws, plates, and intramedullary nails or rods. Staples and clamps are also used occasionally for osteotomy or fracture fixation. Autogenous bone grafts, allografts, and bone graft substitutes are frequently used for the treatment of bone defects of various causes. For infected fractures as well as for treatment of bone infections, antibiotic beads are frequently used.

Objective. To review imaging patterns and injury mechanisms in patients with thoracolumbar facet instability (TFI). Design. Imaging studies for thoracolumbar osseous injuries over a 2-year period were reviewed. Imaging findings, injury pattern and reported mechanism of injury were established for patients with TFI. Patients. One hundred and ten patients with thoracolumbar acute, osseous injuries were studied. Results. Eleven of 68 (16.2%) unstable thoracolumbar injuries demonstrated TFI. Seven (64%) of the eleven TFI patients were unrestrained occupants in a motor vehicle accident (MVA) and the remainder were involved in injuries dominated by blunt impact to the back. Only two (18%) had serious, permanent neurological deficits. Conclusion. TFI is a common injury pattern, particularly for unrestrained occupants in MVAs. Characteristic radiographic, CT and MRI findings are presented and correlated with the injury mechanism and clinical findings.

Strain transfer near hydroxyapatite (HA) coated canine hip implants was examined using simulated anatomical loading based on in vivo strain measurements. Strain changes near implants relative to intact control values were in excess of 100% for transverse and principal strains for zero time period (immediate postimplant) specimens. They were generally smaller (100% or less) for axial, transverse, and principal minimums in the same locations for 4 months postimplantation specimens. Cortical bone loss occurred in all implanted femora. The most extensive loss, up to 47%, occurred adjacent to the proximal section of the implant. Extensive trabecular bone formation, over 300% in some regions of each femur, was noted in all implanted femora. Backscattered electron imaging along the HA-coated sections of the implants showed extensive bone bonded to the coating. NOrmal light and UV light micrographs showed direct bone apposition to the implant surfaces and extensive bone formation in all test animals. Microscopy revealed no evidence of any soft tissue layer between the implant and bone. Bone was typically found in direct contact with the implant surface. Histomorphometry indicated that bone formation rates in the implanted femora were elevated, up to 850%, relative to controls. Fewer formation sites were noted on the posterior and lateral (in two cases zero sites). Mineral apposition rates (MAR) from two of the dogs were slightly elevated (from 110-113%) in the implanted femora relative to controls and depressed (to about 83% of controls) in a third.

While joint pain and loss of mobility are common causes of impairment, there are few procedures that can consistently restore the long-term function of damaged articular cartilage. One approach that offers a potential solution for articular cartilage repair is replacement of the damaged cartilage using a tissue-engineered scaffold. The goal of this study was to measure loading and bone attachment in sensate, porous, calcium phosphate ceramic (CPC) coated polybutylene terephthalate (PBT) scaffolds that have been implanted in the medial compartment of the knees of 6 canines. In addition histology, histomorphometry, and scanning electron microscopy (SEM) were used to characterize bone growth into and around the PBT scaffold. In vivo measurements from the calibrated scaffolds indicated that peak loads in the dog knees ranged from 80-120N. Post-sacrifice biomechanical testing indicated that these loads correlated to pressures of 11 ± 1.54 MPa in the medial compartment of the knees. Histology demonstrated a bone volume of 6.8 ± 8.8% within the scaffold pores and an osteoid volume of 64.9 ± 17.2%. Histomorphometry indicated an increased bone formation rate within the scaffold pores, 8.2E-5 ± 5.9E-5 μm3 /μm2 /day, compared to 1.3E-5 ± 0.8E-5 mm3 /μm2 /day in control knees. SEM demonstrated less bone within the scaffold pores compared to the extensive amount of bone surrounding the scaffold and in intimate contact with the CPC particles. These results demonstrate that the scaffold is mechanically coupled to the bone. In addition, the increased bone formation rate and osteoid within the PBT pores demonstrate that bone formation is still occurring 6 months post-op. Currently studies are focused on the integration of PBT scaffolds containing a tissue-engineered cartilage covering into damaged articular cartilage.

Twenty-one infected total knee arthroplasties (TKA) in 21 patients were treated from September 1980 through October 1987. Of these, 15 were followed for more than one year. Treatment of these patients consisted of thorough debridement of all infected tissue and components; a cement spacer was used in ten patients. The cement was impregnated with antibiotics. This procedure was followed for an average of 4.2 weeks with intravenous antibiotics and TKA utilizing antibiotic-impregnated cement. Five patients had rheumatoid arthritis and ten had osteoarthritis. The organisms included Staphylococcus coagulase negative (seven patients), Streptococcus group B (two patients), Streptococcus bovis (one patient), Enterococcus (one patient), Staphylococcus coagulase positive and Bacillus circulans (one patient), Staphylococcus coagulase negative and Enterococcus (one patient), Staphylococcus coagulase negative and Pseudomonas aeuriginosa (one patient), and Clostridium perfringens (one patient). Of the 15 patients, 12 appeared to be free of infection, two were obvious failures and required knee fusion, and one was suspected of having continued infection at five years and was treated elsewhere. Eleven patients with revision TKA were available for follow-up examinations at an average of 2.9 years (range, one to six years). One patient died five years after reimplantation but had been functioning well. One patient functioning at three years postreimplantation did not return for a later follow-up examination. The average knee score (modification of the Hospital for Special Surgery Knee Score) was 75.5 points (range, 48-94); average flexion was 81 degrees (range, 52 degrees-120 degrees), and average extension was +6 degrees (range, 0 degrees-30 degrees).(ABSTRACT TRUNCATED AT 250 WORDS)