Comparison of bacteria isolated from open fractures following debridement and subsequent infection.

BACKGROUND: One of the major objectives for the management of open fractures is to prevent bone and soft tissue infection. Here, we identified species and drug sensitivities of bacterial isolates recovered during open fracture debridement and after infection and compared the results between the two time points. METHODS: A total of 61 hospitalized patients with open fractures who developed post-operative wound infection between October 2016 and December 2017 were included in this study. The cohort included 43 males and 18 females aged between 4 and 72 years. Patients were admitted to hospital 1-14 h after injury. Samples were collected after debridement and after infection and submitted for bacterial culture. Resulting isolates were identified using a VITEK 2 Bacterial Identification System and tested for drug sensitivity using the disc diffusion method. Results from the two time points were then compared. RESULTS: The positive bacterial culture rate following debridement was relatively low (14/61, 22.9%). In addition, bacteria cultured after debridement were generally inconsistent with those cultured after wound infection, with a concordance rate of only 3.3% (2/61). Gram-negative bacteria accounted for 91.3% (63/69) of isolates recovered from wound infections following surgery, among which Acinetobacter baumannii was baumannii was the predominant pathogen, accounting for 49.3% (42/69) of all isolates. Overall, 60.8% (42/69) of postoperative infections were caused by multi-drug resistant bacteria, with A. baumannii isolates accounting for 80.9% (34/42) of these cases. Rates of cefoperazone/sulbactam resistance were relatively low among the isolates (15/34, 44.1%), and most isolates showed a sensitive or intermediate resistance phenotype. CONCLUSIONS: Results of bacterial culture after debridement could not predict pathogenic bacteria causing postoperative infection. Therefore, we propose that open fracture infections are predominantly nosocomial and are mainly caused by multidrug-resistant Gram-negative bacteria. Further attention should be paid to the control of these pathogens in clinical settings.

Analysis of medial tibial plateau fracture injury patterns using quantitative 3D measurements.

BACKGROUND: The Wahlquist system classifies tibial medial plateau fractures into three types based on the sagittal fracture line location, with type C at highest risk of complications. However, the injury mechanism of tibial medial plateau fractures, especially tibial rotation movement, remains unclear. The purpose of the present study was to determine the injury patterns of medial tibial plateau fractures using 3D model simulation and quantitative 3D measurements. METHODS: Seventy-eight consecutive AO/OTA type 41-B tibial plateau fractures were retrospectively analyzed using CT-based 3D models and quantitative 3D measurements. The knee posture at the moment of fracture occurrence was simulated, and various knee angles in the sagittal, coronal, and axial planes were measured to evaluate the mechanism of medial tibial plateau fracture. The mean valgus-varus, hyperextension-flexion, and internal-external rotation angles were determined, and the chi-square test was used for comparisons of categorical varus and valgus force data to determine the main force direction in Wahlquist type C fractures. RESULTS: Angle measurements in the coronal planes showed that 28 (35.9%) medial tibial plateau fractures resulted from a varus injury pattern, while 50 fractures (64.1%) resulted from a valgus pattern. Valgus force produced significantly more Wahlquist type C fractures (37 of 50 fractures) than varus force (2 of 28 fractures) (p < 0.05). There was no significant difference in the cases of patients with type C fractures between the tibial internal and external rotation injury patterns(P > 0.05). CONCLUSIONS: Valgus force was the cause of 64.1% of the medial tibia plateau fractures in the present cohort. Furthermore, valgus force produced more Wahlquist type C fractures than varus force. The present findings will help orthopedists understand the injury mechanism of the Wahlquist classification system, and will facilitate the identification of the common features of medial tibial plateau fractures induced by specific injury patterns.

Effect of tibial slope changes on femorotibial contact kinematics after cruciate-retaining total knee arthroplasty.

PURPOSE: The present study was undertaken to evaluate the effect of tibial slope (TS) changes on the femorotibial articular contact kinematics in subjects undergoing posterior cruciate-retaining total knee arthroplasty (CRTKA). METHODS: Eighteen knees in nine patients with medial osteoarthritis who underwent CRTKA using the same size prosthesis were analysed preoperatively and 2 years after TKA. TS changes were calculated on lateral radiographs taken before and after TKA. Knees were classified into two groups according to the change in TS obtained by subtracting the post-operative value from the preoperative value: group 1 (>3°) and group 2 (<3°). The femorotibial articular contact kinematics of knees during weight-bearing flexion were compared between the two groups by two-dimensional/three-dimensional registration. RESULTS: Group 1 showed a continuous posterior translation of the medial femoral condyle during the process of knee flexion, whereas in group 2 the medial femoral condyle experienced paradoxical anterior motion from 20° to 90° of knee flexion. The lateral femoral condyle continuously moved posteriorly in both groups. CONCLUSION: A greater reduction in TS after TKA compared with preoperative TS reduces paradoxical medial femoral condylar movement. This may contribute to improved patient satisfaction after CR TKA. LEVEL OF EVIDENCE: III.

Biomechanical comparison of gourd-shaped LCP versus LCP for fixation of comminuted tibial shaft fracture.

The purpose of this study was to compare monotonic biomechanical properties of gourd-shaped LCP fixation with LCP fixation of human tibial shaft in gap fracture mode. Twenty paired fresh cadaveric human tibias were randomly divided into 4 groups (5 pairs each): (1) axial loading single cycle to failure testing, (2) torsion single cycle to failure testing, (3) 4-point bending single cycle to failure testing, and (4) dynamic 4-point bending testing. A 7-hole 4.5 mm gourd-shaped LCP was secured on the anteromedial surface of 1 randomly selected bone from each pair, respectively, using 6 locking screws in the 1st, 2nd, 3rd, 5th, 6th and 7th hole with the middle hole unfilled and just located at the mid-diaphysis of the tibia. A 7-hole 4.5 mm LCP was secured on the other bone with the same method. Standard AO/ASIF techniques were used. After fixation finished, a 10 mm gap in the mid-diaphysis of tibia was created, centrally located at the unfilled hole. The axial, torsional, and bending stiffness and failure strengths were calculated from the collected data in static testings and statistically compared using paired Student's t-test. The 4-point bending fatigue lives of the two constructs were calculated from the dynamic testing data and also statistically compared using paired Student's t-test. Failure modes were recorded and visually analyzed. P<0.05 was considered significant. Results showed that the axial, torsional and bending stiffness of gourd-shaped LCP construct was greater (4%, 19%, 12%, respectively, P<0.05) than that of the LCP construct, and the axial, torsional and bending failure strengths of gourd-shaped LCP construct were stronger (10%, 46%, 29%, respectively, P<0.05) than those of the LCP construct. Both constructs failed as a result of plate plastic torsional deformation. After axial loading and 4-point bending testings, LCP failed in term of an obvious deformation of bent apex just at the unfilled plate hole, while the gourd-shaped LCP failed in term of a deformation of bent arc between the 3rd and 5th holes, which indicated a more consistent stress distribution on gourd-shaped LCP. Fatigue life of gourd-shaped LCP construct was significantly greater than LCP construct (153 836±2 228 vs. 132 471±6 460 cycles, P<0.01). All constructs failed as a result of fracture of the plate through the compression hole of the unfilled combination screw hole. The biomechanical testing showed that gourd-shaped LCP can provide greater stiffness and strength, and longer fatigue life than LCP. The gourd-shaped LCP may be more advantageous mechanically and may reduce the plate breakage rate clinically.

The safety and immunogenicity of a recombinant five-antigen Staphylococcus aureus vaccine among patients undergoing elective surgery for closed fractures: A randomized, double-blind, placebo-controlled, multicenter phase 2 clinical trial.

BACKGROUND: Vaccines are urgently required to control Staphylococcus aureus hospital and community infections and reduce the use of antibiotics. Here, we report the safety and immunogenicity of a recombinant five-antigen Staphylococcus aureus vaccine (rFSAV) in patients undergoing elective surgery for closed fractures. METHODS: A randomized, double-blind, placebo-controlled, multicenter phase 2 clinical trial was carried out in 10 clinical research centers in China. Patients undergoing elective surgery for closed fractures, aged 18-70 years, were randomly allocated at a ratio of 1:1 to receive the rFSAV or placebo at a regimen of two doses on day 0 and another dose on day 7. All participants and investigators remained blinded during the study period. The safety endpoint was the incidence of adverse events within 180 days. The immunogenicity endpoints included the level of specific antibodies to five antigens after vaccination, as well as opsonophagocytic antibodies. RESULTS: A total of 348 eligible participants were randomized to the rFSAV (n = 174) and placebo (n = 174) groups. No grade 3 local adverse events occurred. There was no significant difference in the incidence of overall systemic adverse events between the experimental (40.24 %) and control groups (33.72 %) within 180 days after the first immunization. The antigen-specific binding antibodies started to increase at days 7 and reached their peaks at 10-14 days after the first immunization. The rapid and potent opsonophagocytic antibodies were also substantially above the background levels. CONCLUSIONS: rFSAV is safe and well-tolerated in patients undergoing elective surgery for closed fractures. It elicited rapid and robust specific humoral immune responses using the perioperative immunization procedure. These results provide evidence for further clinical trials to confirm the vaccine efficacy. China's Drug Clinical Trials Registration and Information Publicity Platform registration number: CTR20181788. WHO International Clinical Trial Registry Platform identifier: ChiCTR2200066259.

[Clinical therapeutic strategies of refracture after bone transport for tibial bone defect].

OBJECTIVE: To explore the clinical therapeutic strategies of refracture after Ilizarov bone transport technique in the treatment of tibial bone defect. METHODS: A retrospective study was performed on 19 patients with infected tibial bone defect treated by Ilizarov bone transport technique and then refracture from August 2010 to January 2020, including 18 males and 1 female with an average age of (37.7±13.0) years old ranging from 15 to 66 years old. Cause of injury invlved falling injury in 4 cases, crashing injury 1 case, crushing injury in 1 case and without obvious injury history in 13 cases. The ipsilateral distal femoral fracture in 2 cases occurred before the external fixator of tibia was removed, and the other 17 cases had a minimum of 1 day and a maximum of 30 months after the external fixator had been removed. The site of refracture was at regenerative zone in 8 cases, at docking site in 9 cases, at ipsilateral femoral shaft in 2 cases. According to the modified Simpson classification proposed by the author, the refracture was classified. The treatment of refracture include plaster splint, traction or external fixation. Bone healing and function were evaluated according to the standards of the Association for the Study and Application of the Method of Ilizarov(ASAMI). RESULTS: All patients were followed up, and the duration ranged from 9 to 17 months with an average of (12.3±3.2) months. According to the modified Simpson classification, there were 3 cases of type Ⅰa, 1 case of type Ⅰb, 3 cases of type Ⅰc, 1 case of type Ⅱ, 9 cases of type Ⅲ and 2 cases of type Ⅴ. All the refractures healed without infection or malunion. The fracture healing time of conservative treatment for 6 cases were 3, 5, 3, 2, 2, 2 months fespectively;and the healing time of fracture treated by surgery for 13 cases was 2 to 6 months, with an average of(4.4±1.4) months. According to ASAMI evaluation criteria, bony results showed all patients obtained excellent results, and functional results showed 6 patients got excellent results, 13 good beacause of ankle or knee stiffness. CONCLUSION: The modified Simpson classification could contain most clinical types of refracture after bone transport, and the external fixation is a simple and effective method for refracture.

Injury pattern simulation and mapping of complex tibial plateau fractures that involve the posterior plateau with three-dimensional computed tomography.

BACKGROUND: Tibial plateau fractures involving the posterior plateau (TPFIPs) are complex intra-articular fractures that are difficult to stabilize. Understanding the characteristics of these fractures together with the injury pattern is beneficial for surgeons to choose an optimal treatment strategy. However, the complicated morphology and injury patterns of TPFIPs are poorly characterized. The purpose of this retrospective study was to investigate the injury patterns and fracture characteristics of complex TPFs by applying three-dimensional (3D) simulation and fracture mapping methods. METHODS: In total, 171 TPFIPs were retrospectively reviewed, and the injury pattern was simulated and analyzed by applying a 3D method with Mimics software, which allowed matching of the fractured articular surfaces of the tibial plateau to the femoral condyle surface. The major articular fracture lines were mapped and then superimposed on a template. The tibial motion angle after fracture injury pattern simulation and the major fracture line angle were quantitatively analyzed, while the injury patterns and fracture characteristics were qualitatively analyzed. RESULTS: Four main injury patterns with distinctive fracture characteristics were observed in this study. In total, 72 TPFs exhibited extension as the pattern of injury with a split posterolateral fragment, and 61 fractures exhibited the flexion-internal rotation injury pattern; compression was the main feature of posterolateral fractures. Furthermore, 21 fractures exhibited the flexion-external rotation injury pattern, with a small posteromedial fragment, and 17 fractures exhibited the flexion-neutral injury pattern, with both parts of the posterior plateau fracture and anterior dislocation being observable. The major articular fracture line angles were significantly different between the four main injury patterns (85.92°, 46.79°, 148.26°, and 16.21°, median values, P<0.05). Two injury patterns, namely, flexion-internal rotation and flexion-external rotation, exhibited rotation in the axial plane (24.13°±8.33°, -15.13°±5.14°, P<0.05). CONCLUSIONS: In this study, a method involving a simulated injury pattern was developed and combined with evaluations of fracture characteristics, including two-dimensional (2D) and 3D analyses, to comprehensively describe both the morphologies and injury patterns of TPFIPs.

[Treatment of complex calcaneal fractures under computer navigation: report of 130 feet].

OBJECTIVE: To investigate the effects of computer navigation in the treatment of intra-articular calcaneal fractures. METHODS: 130 feet in 110 patients with intra-articular calcaneal fractures, 57 calcanei with fracture of Sander's type II, 45 of type III, and 28 cases of type IV, were treated with internal fixation under computer navigation, and were followed up for 16.3 months (6 - 24 months). RESULTS: According to the Maryland Foot Score system, excellent result was noted in 63 feet, good result in 57 feet, and fair result in 10 feet, with the excellent and good rates being 92.31% together. CONCLUSION: Using computer navigation to treat intra-articular calcaneal fractures is one of the best ways for treatment of calcaneal fractures.

Management of traumatic hemipelvectomy: an institutional experience on four consecutive cases.

BACKGROUND AND OBJECTIVE: The incidence of traumatic hemipelvectomy is rare, but it is a devastating injury. Recently, an increasing number of patients with traumatic hemipelvectomy are admitted to trauma centers alive due to improvements of the pre-hospital care. Successful management requires prompt recognition of the nature of this injury and meticulous surgical technique. We present our successful experiences on four cases of traumatic hemipelvectomy in the past nine years. PATIENTS AND METHODS: Four cases with traumatic hemipelvectomy were admited to our hospital from June 21, 2002 to September 3, 2011. All injuries occurred due to vehicle accident and all patients were in a state of severe hypotension, with two of them having anal lacerations. These four cases were treated immediately with resuscitation, control of hemorrhage, early amputation, repeated debridement and closure of the wounds. An angiographic embolization was given to control hemorrhage in two of the cases preoperatively. One case underwent fecal diversion. Wound infection occurred in all of cases which was successfully controlled by repeated debridements, effective anti-biotic regimen, split-thickness skin grafts. RESULTS: All four cases were saved successfully with well-healed wounds during follow up from 1 to 7 years. They were able to walk by themself using crutches. CONCLUSION: Adhering to the surgery principles of damage control including appropriate resuscitation, hemorrhage control, coagulopathy correction and multiple debridements and closure of the wounds in reasonable period of time can save the life of cases suffering from severe pelvic ring injury.