Wang Pf

Biomechanical comparison of different stabilization constructs for unstable posterior wall fractures of acetabulum. A cadaveric study.

Purpose Operative treatment of unstable posterior wall fractures of acetabulum has been widely recommended. This laboratory study was undertaken to evaluate static fixation strength of three common fixation constructs: interfragmentary screws alone, in combination with conventional reconstruction plate, or locking reconstruction plate. Methods Six formalin-preserved cadaveric pelvises were used for this investigation. A posterior wall fracture was created along an arc of 40–90 degree about the acetabular rim. Three groups of different fixation constructs (two interfragmentary screws alone; two interfragmentary screws and a conventional reconstruction plate; two interfragmentary screws and a locking reconstruction) were compared. Pelvises were axial loaded with six cycles of 1500 N. Dislocation of superior and inferior fracture site was analysed with a multidirectional ultrasonic measuring system. Results: No statistically significant difference was found at each of the superior and inferior fracture sites between the three types of fixation. In each group, the vector dislocation at superior fracture site was significantly larger than inferior one. Conclusions All those three described fixation constructs can provide sufficient stability for posterior acetabular fractures and allow early mobilization under experimental conditions. Higher posterior acetabular fracture line, transecting the weight-bearing surface, may indicate a substantial increase in instability, and need more stable pattern of fixation.

Treatment of bone nonunion and bone defects associated with unsuccessful humeral condylar fracture repair with autogenous iliac bone reconstruction

BACKGROUND Our preliminary study retrospectively assessed outcomes after the use of autogenous iliac bone grafts combined with internal fixation to repair refractory bone nonunions and bone defects associated with supracondylar or intracondylar humeral fractures, or both. MATERIALS AND METHODS We identified 22 patients (14 men and 8 women) with a mean age of 33.8 years (range, 17-60 years) with bone nonunion and severe bone defects associated with supracondylar or intercondylar humerus fractures, or both. The humeral condyle in each patient was anatomically reconstructed using autologous iliac bone grafts and internal fixation. Active functional exercise was initiated 3 to 4 weeks after surgery. The following variables were assessed: preoperative and postoperative elbow range of motion, Mayo Elbow Performance Score (MEPS), and postoperative complications. RESULTS Mean follow-up was 38.6 months. Mean duration until bone union was 5.6 months. Preoperatively, 16 patients had a fair or poor MEPS (<75). At final follow-up MEPS was excellent (>90) in 8, good (75-90) in 9, fair (60-74) in 4, and poor (<60) in 1 patient. Postoperative heterotopic ossification anterior to the elbow joint occurred in 2 patients. CONCLUSIONS Our preliminary results suggest that anatomic reconstruction of the humeral condyle using autogenous iliac bone grafting with internal fixation can improve elbow joint function in patients with bone nonunion and bone defects associated with supracondylar or intracondylar humeral fractures, or both. Larger scale studies are warranted to confirm our findings and compare the efficacy of this vs other surgical approaches.

Deletion of mammalian sterile 20-like kinase 1 attenuates neuronal loss and improves locomotor function in a mouse model of spinal cord trauma

Neuronal cell death following spinal cord injury (SCI) is an important contributor to neurological deficits. The purpose of our work was to delineate the function of mammalian sterile 20-like kinase 1 (Mst1), a pro-apoptotic kinase and key mediator of apoptotic signaling, in the pathogenesis of an experimental mouse model of SCI. Male mice received a mid-thoracic spinal contusion injury, and it was found that phosphorylation of Mst1 at the injured site was enhanced significantly following SCI. Furthermore, when compared to the wild-type controls, Mst1-deficient mice displayed improved locomotor function by increased Basso mouse scale score. Deletion of Mst1 in mice attenuated loss of motor neurons and suppressed microglial and glial activation following SCI. Deletion of Mst1 in mice reduced apoptosis via suppressing cytochrome c release and caspase-3 activation following SCI. Deletion of Mst1 attenuated mitochondrial dysfunction and increased ATP formation following SCI. Deletion of Mst1 in mice inhibited local inflammation following SCI, evidenced by reduced activities of myeloperoxidase and protein levels of TNF-α, IL-1β, and IL-6. In conclusion, the present study demonstrated that deletion of Mst1 attenuated neuronal loss and improved locomotor function in a mouse model of SCI, via preserving mitochondrial function, attenuating mitochondria-mediated apoptotic pathway, and suppressing inflammation, at least in part.

Degradability, biocompatibility, and osteogenesis of biocomposite scaffolds containing nano magnesium phosphate and wheat protein both in vitro and in vivo for bone regeneration.

In this study, bioactive scaffold of nano magnesium phosphate (nMP)/wheat protein (WP) composite (MWC) was fabricated. The results revealed that the MWC scaffolds had interconnected not only macropores (sized 400–600 μm) but also micropores (sized 10–20 μm) on the walls of macropores. The MWC scaffolds containing 40 w% nMP had an appropriate degradability in phosphate-buffered saline and produced a weak alkaline microenvironment. In cell culture experiments, the results revealed that the MWC scaffolds significantly promoted the MC3T3-E1 cell proliferation, differentiation, and growth into the scaffolds. The results of synchrotron radiation microcomputed tomography and analysis of the histological sections of the in vivo implantation revealed that the MWC scaffolds evidently improved the new bone formation and bone defects repair as compared with WP scaffolds. Moreover, it was found that newly formed bone tissue continued to increase with the gradual reduction of materials residual in the MWC scaffolds. Furthermore, the immunohistochemical analysis further offered the evidence of the stimulatory effects of MWC scaffolds on osteogenic-related cell differentiation and new bone regeneration. The results indicated that MWC scaffolds with good biocompability and degradability could promote osteogenesis in vivo, which would have potential for bone tissue repair.

Application of a Shape-Memory Alloy Concentrator in Displaced Patella Fractures: Technique and Long-Term Results

&NA; Operative treatment is usually recommended in displaced patella fractures. Several techniques have been advocated for internal fixation of patella fractures. Despite the relatively good clinical outcomes that have been demonstrated in many studies, postoperative morbidities such as fixation failure, nonunion, infection, and knee stiffness are not uncommon. We present a new alternative treatment technique for displaced patellar fractures. Between April 1995 and May 2005, we used the Nitinol Patella Concentrator (NTPC) to treat 156 consecutive patients with displaced patellar fractures. Injuries arose from vehicular accidents in 56 (35.9%) cases, direct falls onto the knee in 85 (54.5%) cases, and sports injuries in 15 (9.6%) cases. The mean patient age was 46.3 years (range, 25‐77 years). Clinical assessments were made using the Böstman knee score and the MOS SF‐36 questionnaire (Medical Outcomes Study 36‐item short‐form health survey), which were both recorded at the final follow‐up visit. The mean follow‐up was 7.3 years (range, 6‐17 years). At the final follow‐up, the Böstman knee scores were excellent in 88 cases (28‐30), good in 55 (20‐27), and unsatisfactory in 13 (<20). According to the MOS SF‐36 evaluation, the average score was 84.5 (range, 62‐91). Treatment of patellar fracture with the NTPC not only may serve as an effective and rigid fixation method in multifragmented displaced and inferior pole fractures, but also may provide continuous concentrative compression during the osseous healing process. Thus, use of the NTPC may help restore the functional integrity of the extensor mechanism and permit early rehabilitation with a lower incidence of postoperative complications.