OBJECTIVETo study biomechanical changes of newly formed bones 24 weeks after repairing large defects of long bones of goats using heterogeneous deproteinated bone (DPB) prepared by modified methods as an engineering scaffold.

METHODSAccording to a fully randomized design, 18 goats were evenly divided into three groups: normal bone control group (Group A), autologous bone group (Group B) and experimental group (Group C). Each goat in Groups B and C were subjected to the periosteum and bone defect at middle-lower part of the right tibia (20% of the whole tibia in length), followed by autologous bone or DPB plus autologous MSCs + rhBMP2 implantation, respectively and semi-ring slot fixation; while goats in Group A did not perform osteotomy. At 24 weeks after surgery, biomechanical tests were carried out on the tibias.

RESULTSAt 24 weeks after surgery, the results of anti-compression test on tibias in three groups were recorded by a functional recorder presented as linear pressure-deformation curve. The shapes of the curves and their change tendency were similar among three groups. The ultimate pressure values were 10.74 MPa+/-1.23 MPa, 10.11 MPa+/-1.35 MPa and 10.22 MPa+/-1.32 MPa and fracture compression rates were 26.82%+/-0.87%, 27.17%+/-0.75% and 28.22%+/-1.12% in Groups A, B and C, respectively. Comparisons of anti-compression ultimate pressures and fracture compression rates among three groups demonstrated no significant difference (P(AB) equal to 0.415, P(BC) equal to 0.494). Three-point anti-bend test on tibias was recorded as load-deformation curves, and the shapes of the curves and their change tendency were similar among three groups. The ultimate pressure values of the anti-bend test were 481.52 N+/-12.45 N, 478.34 N+/-14.68 N and 475.62 N+/-13.41 N and the fracture bend rates were 2.62 mm+/-0.12 mm, 2.61 mm+/-0.15 mm and 2.81 mm+/-0.13 mm in Groups A, B and C, respectively. There was no significant difference between groups (P(AB) equal to 0.7, P(BC) equal to 0.448). The ultimate anti-torsion torque values were 6.55 Nm+/-0.25 Nm, 6.34 Nm+/-0.18 Nm and 6.42 Nm+/-0.21 Nm and fracture torsion rates were 29.51 degree+/-1.64degree, 28.88 degree+/-1.46 degree and 28.81 degree+/-1.33 degree in Groups A, B and C, respectively. There was no significant difference between groups (P(AB) equal to 0.123, P(BC) equal to 0.346).

CONCLUSIONSThe biomechanical characteristics of newly formed bones from heterogeneous DPB for repairing large segmental long bone defect are comparable to those of normal bones and autologous bones. DPB has the potential for clinical usage as bone graft material.

Animals ; Biomechanical Phenomena ; Female ; Goats ; Male ; Proteins ; Tibia ; physiology ; surgery ; Tissue Engineering ; Torsion, Mechanical

Dynamic loads at knee joint of amputee are fundamental for rehabilitation of knee injury and prosthesis design. In this paper, a 3-D model for calculation of dynamic load at knee joint of trans-tibial amputee was developed. Gait analysis was done on three terrains including normal level walking, upstairs and downstairs. Dynamic loads at knee joint were calculated during one gait cycle. The results show that gait patterns and dynamic loads at knee joint were different among these three terrains. Although the general waveforms were about the same, the motion range of knee joint, ground reaction forces and loads at knee joint when walking upstairs or downstairs were larger than those in a normal level walking. The quantitative findings provide the theoretical basis of gait analysis and prosthesis design for trans-tibial amputee.
Amputation Stumps ; physiopathology ; Artificial Limbs ; Biomechanical Phenomena ; Gait ; physiology ; Humans ; Knee Joint ; physiopathology ; Leg ; physiopathology ; surgery ; Prosthesis Design ; Stress, Mechanical ; Tibia ; physiopathology ; surgery ; Walking ; physiology ; Weight-Bearing ; physiology

Posterior-stabilized total knee prostheses have been widely used in orthopedic clinical treatment of knee osteoarthritis, but the patients and surgeons are still troubled by the complications, for example severe wear and fracture of the post, as well as prosthetic loosening. Understanding the in vivo biomechanics of knee prostheses will aid in the decrease of postoperative prosthetic revision and patient dissatisfaction. Therefore, six different designs of posterior-stabilized total knee prostheses were used to establish the musculoskeletal multibody dynamics models of total knee arthroplasty respectively, and the biomechanical differences of six posterior-stabilized total knee prostheses were investigated under three simulated physiological activities: walking, right turn and squatting. The results showed that the post contact forces of PFC Sigma and Scorpio NGR prostheses were larger during walking, turning right, and squatting, which may increase the risk of the fracture and wear as well as the early loosening. The post design of Gemini SL prosthesis was more conductive to the knee internal-external rotation and avoided the edge contact and wear. The lower conformity design in sagittal plane and the later post-cam engagement resulted in the larger anterior-posterior translation. This study provides a theoretical support for guiding surgeon selection, improving posterior-stabilized prosthetic design and reducing the prosthetic failure.
Arthroplasty, Replacement, Knee/methods* ; Biomechanical Phenomena ; Humans ; Knee Joint/surgery* ; Knee Prosthesis ; Prosthesis Design ; Range of Motion, Articular/physiology* ; Tibia/surgery*

BACKGROUND: Degenerative osteoarthritis of the knee usually shows arthritic change in the medial tibiofemoral joint with severe varus deformity. In total knee arthroplasty (TKA), the medial release technique is often used for achieving mediolateral balancing. But, in a more severe varus knee, there are more difficult technical problems. Bony resection of the medial proximal tibia (MPT) as an alternative technique for achieving soft tissue balancing was assessed in terms of its effectiveness and possibility of quantification. METHODS: TKAs were performed in 78 knees (60 patients) with vertical bone resection of the MPT for soft tissue balancing from September 2011 to March 2013. During operation, the medial and lateral gaps were measured before and after the bony resection technique. First, the correlation between the measured thickness of the resected bone and the change in medial and lateral gaps was analyzed. Second, the possibility of quantification of each parameter was evaluated by linear regression and the coefficient ratio was obtained. RESULTS: A significant correlation was identified between alteration in the medial gap change in extension and the measured thickness of the vertically resected MPT (r = 0.695, p = 0.000). In the medial gap change in flexion, there was no statistical significance (r = 0.214, p = 0.059). When the MPT was resected at an average thickness of 8.25 +/- 1.92 mm, the medial gap in extension was increased by 2.94 +/- 0.87 mm. In simple linear regression, it was predictable that MPT resection at a thickness of 2.80 mm was required to increase the medial gap by 1.00 mm in knee extension. CONCLUSIONS: The method of bone resection of the MPT can be considered effective with a predictable result for achieving soft tissue balancing in terms of quantification during TKA.
Aged ; Aged, 80 and over ; Arthroplasty, Replacement, Knee/*methods/*statistics & numerical data ; Female ; Humans ; Knee/*physiology/*surgery ; Male ; Middle Aged ; Osteoarthritis, Knee/*surgery ; Tibia/*physiology/*surgery

BACKGROUND: The purpose of this study was to compare the initial stability of anatomical and non-anatomical single bundle anterior cruciate ligament (ACL) reconstruction and to determine which would better restore intact knee kinematics. Our hypothesis was that the initial stability of anatomical single bundle ACL reconstruction would be superior to that of non-anatomical single bundle ACL reconstruction. METHODS: Anterior tibial translation (ATT) and internal rotation of the tibia were measured with a computer navigation system in seven pairs of fresh-frozen cadaveric knees under two testing conditions (manual maximum anterior force, and a manual maximum anterior force combined with an internal rotational force). Tests were performed at 0, 30, 60, and 90 degrees of flexion with the ACL intact, the ACL transected, and after reconstruction of one side of a pair with either anatomical or non-anatomical single bundle ACL reconstruction. RESULTS: Under manual maximal anterior force, both reconstruction techniques showed no significant difference of ATT when compared to ACL intact knee state at 30degrees of knee flexion (p > 0.05). Under the combined anterior and internal rotatory force, non-anatomical single-bundle ACL reconstruction showed significant difference of ATT compared to those in ACL intact group (p < 0.05). In contrast, central anatomical single bundle ACL reconstruction showed no significant difference of ATT compared to those in ACL intact group (p > 0.05). Internal rotation of the tibia showed no significant difference in the ACL intact, the ACL transected, non-anatomical reconstructed and anatomical reconstructed knees. CONCLUSIONS: Anatomical single bundle ACL reconstruction restored the initial stability closer to the native ACL under combined anterior and internal rotational forces when compared to non-anatomical ACL single bundle reconstruction.
Aged ; Aged, 80 and over ; Anterior Cruciate Ligament/*anatomy & histology/physiology/*surgery ; Anterior Cruciate Ligament Reconstruction/*methods ; Biomechanics/physiology ; Cadaver ; Humans ; Knee Joint/*anatomy & histology/physiology/*surgery ; Middle Aged ; Random Allocation ; Range of Motion, Articular/physiology ; Tibia/anatomy & histology/physiology/surgery

OBJECTIVETo assess the effect of muscle contraction on bone capillary permeability.

METHODSThirty female New Zealand white rabbits were randomly divided into the experimental and control groups (n=15). The bone chambers were implanted medially into the right tibiae of the rabbit, and in the experimental group, the rabbits were stimulated by transcutaneous electrical nerve stimulator (TENS) at 4 Hz (1 h/day, 6 days/week) starting from week 2. From week 3, intravital microscopic observation was carried out weekly till week 10, and the vasculature in the tibiae was observed under fluorescent microscope with FITC and RITC staining. All the images were analyzed by Metamorph program.

RESULTSThe bone capillary permeability increased significantly in the experimental group.

CONCLUSIONSkeletal muscle contraction can increase the capillary permeability.

Animals ; Capillary Permeability ; physiology ; Female ; Implants, Experimental ; Muscle Contraction ; physiology ; Muscle, Skeletal ; physiology ; Rabbits ; Random Allocation ; Tibia ; blood supply ; surgery ; Transcutaneous Electric Nerve Stimulation

BACKGROUND: Despite the importance of soft tissue balancing during total knee arthroplasty (TKA), all estimating techniques are dependent on a surgeon's manual distraction force or subjective feeling based on experience. We developed a new device for dynamic gap balancing, which can offer constant load to the gap between the femur and tibia, using pneumatic pressure during range of motion. METHODS: To determine the amount of distraction force for the new device, 3 experienced surgeons' manual distraction force was measured using a conventional spreader. A new device called the consistent load pneumatic tensor was developed on the basis of the biomechanical tests. Reliability testing for the new device was performed using 5 cadaveric knees by the same surgeons. Intraclass correlation coefficients (ICCs) were calculated. RESULTS: The distraction force applied to the new pneumatic tensioning device was determined to be 150 N. The interobserver reliability was very good for the newly tested spreader device with ICCs between 0.828 and 0.881. CONCLUSIONS: The new pneumatic tensioning device can enable us to properly evaluate the soft tissue balance throughout the range of motion during TKA with acceptable reproducibility.
Arthroplasty, Replacement, Knee/*instrumentation/methods ; Biomechanics ; Equipment Design ; Femur/surgery ; Humans ; Knee Joint/physiology/*surgery ; Mechanical Processes ; Range of Motion, Articular ; Reproducibility of Results ; Tibia/surgery

OBJECTIVETo compare the surface apposition and the bone response at early period of implantation in two differently treated implants.

METHODSThe implants were subject to double acid-etched-H2O2/HCl-heat treatment and double acid-etching treatment, and then randomly implanted into the tibia of rabbits. After 2, 4, 8 weeks of follow up, the bone specimens containing implants were prepared and examined by a field emission SEM and EDX.

RESULTA layer rich with calcium and phosphorus was clearly demonstrated on the implants surface of both groups after 2 weeks of implantation, but it was mostly disappeared after 4 weeks. There were large amounts of osteoblasts cells on double acid-etched-H2O2/HCl-heat treated implants surface indicating the initiation of osteogenesis. After 8 weeks of implantation some new bones were attached on the implants surface in both groups, more bones attached were shown on double acid-etched- H2O2/HCl-heat treated implants surface.

CONCLUSIONA calcium and phosphorus-rich layer was formed on the implants surface of both groups at early period of implantation.

Animals ; Dental Implantation ; Dental Implants ; Dental Materials ; chemistry ; Dental Prosthesis Design ; Hydrogen Peroxide ; chemistry ; Osseointegration ; physiology ; Osteogenesis ; physiology ; Rabbits ; Surface Properties ; Tibia ; surgery ; ultrastructure ; Titanium ; chemistry

BACKGROUND: Anatomic footprint restoration of anterior cruciate ligament (ACL) is recommended during reconstruction surgery. The purpose of this study was to compare and analyze the femoral and tibial tunnel positions of transtibial single bundle (SB) and transportal double bundle (DB) ACL reconstruction using three-dimensional computed tomography (3D-CT). METHODS: In this study, 26 patients who underwent transtibial SB ACL reconstruction and 27 patients with transportal DB ACL reconstruction using hamstring autograft. 3D-CTs were taken within 1 week after the operation. The obtained digital images were then imported into the commercial package Geomagic Studio v10.0. The femoral tunnel positions were evaluated using the quadrant method. The mean, standard deviation, standard error, minimum, maximum, and 95% confidence interval values were determined for each measurement. RESULTS: The femoral tunnel for the SB technique was located 35.07% +/- 5.33% in depth and 16.62% +/- 4.99% in height. The anteromedial (AM) and posterolateral (PL) tunnel of DB technique was located 30.48% +/- 5.02% in depth, 17.12% +/- 5.84% in height and 34.76% +/- 5.87% in depth, 45.55% +/- 6.88% in height, respectively. The tibial tunnel with the SB technique was located 45.43% +/- 4.81% from the anterior margin and 47.62% +/- 2.51% from the medial tibial articular margin. The AM and PL tunnel of the DB technique was located 33.76% +/- 7.83% from the anterior margin, 45.56% +/- 2.71% from the medial tibial articular margin and 53.19% +/- 3.74% from the anterior margin, 46.00% +/- 2.48% from the medial tibial articular margin, respectively. The tibial tunnel position with the transtibial SB technique was located between the AM and PL tunnel positions formed with the transportal DB technique. CONCLUSIONS: Using the 3D-CT measuring method, the location of the tibia tunnel was between the AM and PL footprints, but the center of the femoral tunnel was at more shallow position from the AM bundle footprint when ACL reconstruction was performed by the transtibial SB technique.
Adult ; Anterior Cruciate Ligament Reconstruction/*methods ; *Femur/radiography/surgery ; Humans ; Imaging, Three-Dimensional/*methods ; Knee Joint/physiology ; Male ; Prospective Studies ; Surgery, Computer-Assisted/*methods ; *Tibia/radiography/surgery ; Tomography, X-Ray Computed

OBJECTIVETo study whether tissue engineered bone can repair the large segment bone defect of large animal or not. To observe what character the fascia flap played during the osteanagenesis and revascularization process of tissue engineered bone.

METHODS9 Chinese goats were made 2 cm left tibia diaphyseal defect. The repairing effect of the defects was evaluated by ECT, X-ray and histology. 27 goats were divided into three groups: group of CHAP, the defect was filled with coral hydroxyapatite (CHAP); group of tissue engineered bone, the defect was filled with CHAP + bone marrow stroma cells (BMSc); group of fascia flap, the defect was filled with CHAP + BMSc + fascia flap. After finished culturing and inducing the BMSc, CHAP of group of tissue engineered bone and of fascia flap was combined with it. Making fascia flap, different materials as described above were then implanted separately into the defects. Radionuclide bone imaging was used to monitor the revascularization of the implants at 2, 4, 8 weeks after operation. X-ray examination, optical density index of X-ray film, V-G staining of tissue slice of the implants were used at 4, 8, 12 weeks after operation, and the biomechanical character of the specimens were tested at 12 weeks post operation.

RESULTSIn the first study, the defect showed no bone regeneration phenomenon. 2 cm tibia defect was an ideal animal model. In the second study, group of CHAP manifested a little trace of bone regeneration, as to group of tissue engineered bone, the defect was almost repaired totally. In group of fascia flap, with the assistance of fascia flap which gave more chance to making implants to get more nutrient, the repair was quite complete.

CONCLUSIONSThe model of 2 cm caprine tibia diaphyseal defect cannot be repaired by goat itself and can satisfy the tissue engineering's demands. Tissue engineered bone had good ability to repair large segment tibia defect of goat. Fascia flap can accelerate the revascularization process of tissue engineered bone. And by this way, it augment the ability of tissue engineered bone to repair the large bone defect of goat.

Animals ; Bone Marrow Cells ; cytology ; Bone Marrow Transplantation ; Bone Regeneration ; physiology ; Bone Substitutes ; Cells, Cultured ; Durapatite ; Fascia ; transplantation ; Goats ; Implants, Experimental ; Neovascularization, Physiologic ; Osteogenesis ; Random Allocation ; Stromal Cells ; cytology ; Tibia ; blood supply ; injuries ; surgery ; Tibial Fractures ; surgery ; Tissue Engineering