Segmental bone transport (SBT) using an external fixator is currently a standard treatment for large-diameter bone defects at the donor site with low morbidity. However, long-term application of the device is needed for bone healing. In addition, patients who received SBT treatment sometimes fail to show bone repair and union at the docking site, and require secondary surgery. The objective of this study was to investigate whether a single injection of recombinant human bone morphogenetic protein 2 (rhBMP-2)-loaded artificial collagen-like peptide gel (rhBMP-2/ACG) accelerates consolidation and bone union at the docking site in a mouse SBT model.

Six-month-old C57BL/6J mice were reconstructed by SBT with external fixator that has transport unit, and a 2.0-mm bone defect was created in the right femur. Mice were divided randomly into four treatment groups with eight mice in each group, Group CONT (immobile control), Group 0.2mm/d, Group 1.0mm/d, and Group BMP-2. Mice in Group 0.2mm/d and 1.0mm/d, bone segment was moved 0.2 mm per day for 10 days and 1.0 mm per day for 2 days, respectively. Mice in Group BMP-2 received an injection of 2.0 μg of rhBMP-2 dissolved in ACG into the bone defect site immediately after the defect-creating surgery and the bone segment was moved 1.0 mm/day for 2 days.

All animals were sacrificed at eight weeks after surgery. Consolidation at bone defect site and bone union at docking site were evaluated radiologically and histologically.

At the bone defect site, seven of eight mice in Group 0.2mm/d and two of eight mice in Group 1.0mm/d showed bone union. In contrast, all mice in Group CONT showed non-union at the bone defect site. At the docking site, four of eight mice in Group 0.2 mm/d and three of eight mice in Group 1.0 mm/d showed non-union. Meanwhile, all mice in Group BMP-2 showed bone union at the bone defect and docking sites. Bone volume and bone mineral content were significantly higher in Group 0.2mm/d and Group BMP-2 than in Group CONT. HE staining of tissue from Group 0.2mm/d and Group BMP-2 showed large amounts of longitudinal trabecular bone and regenerative new bone at eight weeks after surgery at the bone defect site. Meanwhile, in Group CONT and Group 1.0mm/d, maturation of regenerative bone at the bone defect site was poor. Differences between groups were analyzed using one-way ANOVA and a subsequent Bonferroni's post-hoc comparisons test. P < 0.05 was considered significant.

rhBMP-2/ACG combined with SBT may be effective for enhancing bone healing in large bone defects without the need for secondary procedures.

Segmental bone transport (SBT) with an external fixator has become a standard method for treatment of large bone defect. However, a long time-application of devices can be very troublesome and complications such as nonunion is sometimes seen at docking site. Although there have been several studies on SBT with large animal models, they were unsuitable for conducting drug application to improve SBT. The purpose of this study was to establish a bone transport model in mice. Six-month-old C57BL/6J mice were divided randomly into bone transport group (group BT) and an immobile control group (group EF). In each group, a 2-mm bone defect was created in the right femur. Group BT was reconstructed by SBT with external fixator (MouseExFix segment transport, RISystem, Switzerland) and group EF was fixed simply with unilateral external fixator (MouseExFix simple). In group BT, a bone segment was transported by 0.2 mm per day. Radiological and histological studies were conducted at 3 and 8 weeks after the surgery. In group BT, radiological data showed regenerative new bone consolidation at 8 weeks after the surgery, whereas high rate of nonunion was observed at the docking site. Histological data showed intramembranous and endochondral ossification. Group EF showed no bone union. In this study, experimental group showed good regenerative new bone formation and was similar ossification pattern to previous large animal models. Thus, the utilization of this bone defect mice model allows to design future studies with standardized mechanical conditions for analyzing mechanisms of bone regeneration induced by SBT.

The reduction for unstable femoral intertrochanteric fracture should be extramedullary, which means that the proximal fragment protrudes for the distal fragment. However, only few articles have compared extramedullary and intramedullary reductions in a biomechanical study. Thus, we created unstable femoral intertrochanteric fracture models using imitational bone (extramedullary and intramedullary groups, each with 12 cases) and evaluated their biomechanical stabilities. The fracture type was 31-A2 according to the AO-OTA Classification of Fractures and Dislocations and greatly lacked bone on the posterior side. We performed compression examination and evaluated stiffness. The implant used for fixation was TFNA (DePuy Synthes). We applied axial compression with 20 adduction in the standing position. Statistical analysis was performed using the Mann-Whitney U test. No significant difference in initial loading force was found between the two groups. However, the axial stiffness of the extramedullary bone showed a significant increase (p < 0.05) in high loading force (800–1000 N). This means that the stability of the extramedullary reduction was superior to that of the intramedullary reduction in terms of high loading force in the standing position. We suggest that antero-medial bony buttress is important for unstable femoral intertrochanteric fractures. These data indicate that extramedullary reduction and fixation for unstable femoral intertrochanteric fractures increase stability.

Introduction

Over the past decade, the use of negative pressure wound therapy (NPWT) devices has increased and expanded to include a wide variety of patients. However, the safety and efficacy of NPWT over skin in open fractures is still unknown. The purpose of this study was to evaluate the complication rate and outcome of open fractures treated by NPWT over closed wounds or flaps.

The purpose of this study is to prove whether Japanese patients undergoing primary total hip arthroplasty (THA) for the hip dysplasia were able to return to sport after surgery.

A questionnaire survey was completed by 77 patients in 9 males and 68 females between 1 and 3 years after surgery. Mean age at surgery was 66.1 (range, 49 to 87).

In the 3 years before surgery 40 (51.9%) patients were participating in sport. By 1 to 3 years after surgery 43 (55.8%) patients were participating in sport. A total of 33 (82.5%) had returned to their sporting activities by 1 to 3 years after surgery in groups who played sports before surgery and 7 (17.5%) were unable to do with the most common reason being “cannot move as much as I wanted”. On the other hand, a total of 10 (27%) had started playing sports after surgery. The sports activities after surgery were the most common being walking, radio calisthenics, and swimming as low-impact sports. A total of 27 (73%) did not play sports before or after surgery with the most common reason being “fear of damage to the hip joint”.

In conclusion, when Japanese patients who have undergone THA for hip dysplasia choose to participate in sports, orthopedic surgeons should provide information with which to evaluate the risk of sports activity and recommend appropriate sports activity.

Introduction

Curved varus intertrochanteric osteotomy of the femur is an excellent and minimally invasive method for the treatment of osteonecrosis of the femoral head or osteoarthritis of the hip for joint preservation. However, the early postoperative complications of this procedure may be due to separation at the osteotomy site and an increase in varus angle due to early partial weight bearing.

On the basis of observations made in recent years, it can be inferred that the incidence of venous thromboembolism (VTE) in Japan is as high as that in Western countries.

Since 2007, the use of fondaparinux for the prophylaxis of VTE following lower-limb orthopedic surgery has been approved for Japanese patients. This study was performed with an aim to investigate the safety and efficacy of fondaparinux for the prevention of VTE following hip surgery in Japanese patients.

From June 2007 to August 2008, we evaluated 141 consecutive patients (148 hips; average age, 65.6) undergoing total hip replacement (THR), consisted of cementless minimally invasive surgery, and hip fracture surgery (HFS), consisted of open reduction and internal fixation or bipolar hemiarthroplasty. We mainly used 2.5 mg of fondaparinux for a period extending up to 14 days. We estimated the symptomatic VTE and asymptomatic deep-vein thrombosis (DVT) rates in patients by ultrasonography performed on preoperative and postoperative day 3. In addition, we evaluated the pre-operative and postoperative plasma D-dimer levels on days 3, 7, and 14.

We determined that both the preoperative and postoperative incidence of symptomatic VTE was 0%. A D-dimer value of 20 ug/ml or higher was not observed on preoperative days 3 and 7; however, this value was observed in 2 hips on postoperative day 14. The incidence of asymptomatic DVT was observed to be 0.8% preoperatively and 4% postoperatively. In particular, the corresponding value following HFS was observed to be 7.7% preoperatively. The incidence of the hemorrhagic event was observed to be 14.9%. Bleeding was mostly observed in the surgical and drainage areas. An overall major bleeding incidence of 0.7% (1 patient) was observed. The corresponding value in patients in whom the administration of fondaparinux was discontinued by day 14 was 18.9%.

The study results indicate that fondaparinux is useful in Japanese patients for the prevention of VTE following hip surgery. However, the administration of this drug should be accompanied by additional measures to prevent the associated side effect of bleeding.