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

It is common belief that consolidated intramedullary nailed trochanteric femur fractures can result in secondary midshaft or supracondylar fractures, involving the distal screws, when short or long nails are used, respectively. In addition, limited data exists in the literature to indicate when short or long nails should be selected for treatment. The aim of this biomechanical cadaveric study was to investigate short versus long Trochanteric Femoral Nail Advanced (TFNA) fixation in terms of construct stability and generation of secondary fracture pattern following trochanteric fracture consolidation.

Eight intact human cadaveric femur pairs were assigned to 2 groups of 8 specimens each for nailing using either short or long TFNA with blade as head element. Each specimen was first biomechanically preloaded at 1 Hz over 2000 cycles in superimposed synchronous axial compression to 1800 N and internal rotation to 11.5 Nm. Following, internal rotation to failure was applied over an arc of 90° within 1 second under 700 N axial load. Torsional stiffness, torque at failure, angle at failure and energy at failure were evaluated. Fracture patterns were analyzed.

Outcomes in the groups with short and long nails were 9.7±2.4 Nm/° and 10.2±2.9 Nm/° for torsional stiffness, 119.8±37.2 Nm and 128.5±46.7 Nm for torque at failure, 13.5±3.5° and 13.4±2.6° for angle at failure, and 887.5±416.9 Nm° and 928.3±461.0 Nm° for energy at failure, respectively, with no significant differences between them, P≥0.167. Fractures through the distal locking screw occurred in 5 and 6 femora instrumented with short and long nails, respectively. Fractures through the lateral entry site of the head element were detected in 3 specimens within each group. For short nails, fractures through the distal shaft region, not interfacing with the implant, were detected in 3 specimens.

From biomechanical perspective, the risk of secondary peri-implant fracture after intramedullary nailed trochanteric fracture consolidation is similar when using short or long TFNA. Moreover, for both nail versions the fracture pattern does not unexceptionally involve the distal locking screw.

Introduction. Since 2005, we have performed implantation of bone marrow-derived mononuclear cells for osteonecrosis of the femoral head in order to improve vascularization and bone repair. This study focused on early bone repair of osteonecrosis of the femoral head after transplantation of bone marrow-derived mononuclear cells (BMMNC). Patients and Methods. Twenty-two patients (30 joints) who had bilateral osteonecrosis followed for more than 2 years after BMMNC implantation were evaluated. Eight women and 14 men were included. Their mean age at surgery was 41 years (range, 18 to 64 years) and the mean follow-up period was 31 months. Pre-operative stage according to the ARCO classification was Stage 2 in 25 joints and Stage 3 in 5 joints. The mean volume ratio of osteonecrosis was 21%. For preparing BMMNC, about 700ml of bone marrow was aspirated from the ilium and centrifuged using a Spectra cell separator (Gambro). The BMMNC were seeded to interconnected porous calcium hydroxyapatite (IP-CHA) and implanted to the osteonecrotic lesion. As a control, cell-free IP-CHA was implanted for 8 patients (9 joints). A woman and 7 men were included. The mean age at surgery was 49 years (range, 28 to 73 years) and the mean follow-up period was 37 months. Preoperative stage was stage 2 in all patients. The mean volume ratio of osteonecrosis was 22%. At post-operative evaluations; progression of collapse, consolidation at reactive zone, post-operative course of volume rate of osteonecrosis, and bone absorption at osteonecrosis was assessed. Results. Shrinkage of osteonecrosis has been observed subsequent to bone consolidation at the transitional zone which progressed from 3 to 6 months post-operatively in the BMMNC-seeded group. Progression of collapse more than 2 mm was detected in 4 joints (13%), and hip arthroplasty was performed in 1 joint (3%). Consolidation at the reactive zone was detected in 28 joints (93%) and the volume rate of osteonecrosis significantly decreased by 12 months after surgery. Bone resorption at the osteonecrotic lesion was observed in 14 joints (47%). Meanwhile, subtle bone consolidation was detected after 12 months post-operatively in the control group. Progression of collapse was observed in 6 joints (67%) and further surgical treatments were needed in 3 joints (33%). Conclusion. This study found that BMMNC was beneficial to osteonecrosis of the femoral head from the viewpoint of prevention of collapse

Objectives

Distraction osteogenesis (DO) mobilises bone regenerative potential and avoids the complications of other treatments such as bone graft. The major disadvantage of DO is the length of time required for bone consolidation. Mesenchymal stem cells (MSCs) have been used to promote bone formation with some good results.