Yoshinobu Oka

Efficacy of titanium dioxide photocatalyst for inhibition of bacterial colonization on percutaneous implants.

The purpose of this study was to evaluate the efficacy of titanium dioxide photocatalyst in inhibition of bacterial colonization on percutaneous implants. Titanium dioxide photocatalyst was prepared by direct oxidization of pure titanium substrate, and a comparative study with pure titanium was performed. The bactericidal ability of the photocatalyst was examined using methicillin-resistant Staphylococcus aureus (MRSA) suspensions in a colony-forming assay according to the Japanese Industrial Standards committee standard. After exposing the MRSA suspension on sample plates to ultraviolet A (UVA) light, the number of surviving bacteria was estimated. Next, an animal model for inhibition of colonization was examined in vivo. Pins were inserted into the femurs of rabbits, were infected with 10(8) colony-forming units of MRSA suspension, and were illuminated with UVA light for 60 min daily; the number of colonizing bacteria was estimated after 7 days. The bactericidal ability of the photocatalyst was apparent after 60 min, when the bacteria had almost disappeared. The number of colonizing bacteria on photocatalytic pins was decreased significantly in vivo. The photocatalyst was effective even against resistant bacterial colonization. Clinically, the incidence of percutaneous implant infection such as pin tract infection in external fixation could be reduced using the titanium photocatalyst.

Measurement of bone electrical impedance in fracture healing

BackgroundAlthough external fixation is widely used for fractures and limb lengthening, evaluation of the time for removing the external fixator is dependent upon radiographic examinations and clinical findings, and a useful method has yet to be established clinically. This study aimed to measure the bone electrical impedance (Z values) non-invasively by using external fixation pins as electrodes, and clarify the relationship with bone union.MethodsThirty rabbits received the external fixation at the right tibia and were assigned to a control group (group C; n = 5) and a fractured group (group F; n = 25). Z values were measured once a week following surgery. The animals of group F were assigned to 5 groups (weeks 2, 3, 4, 5, and 6 after osteotomy, each n = 5). The resistivity (ρ) of the electrical property between electrodes was measured prior to euthanasia, and fracture cross-sectional area (FrA) of the conduction pathway and maximum bending stress (Bmax) were measured following excision of the tibia.ResultsAlthough Z values in group F increased through 5 weeks after surgery, Z values in group C remained constant at 3 weeks, and significant differences were observed between groups at 4, 5, and 6 weeks. The ρ values and FrA in group F decreased through 5 weeks; while Bmax increased, reaching a plateau at 5 weeks.ConclusionsNarrowing of conduction pathway due to the decrease in the contour of fracture area accompanying bone remodeling resulted in an increase of Z values. Both Z values and Bmax in group F reached a peak at 5 weeks, this was believed to be the optimal time for removal of external fixation. These results suggest that measurement of Z values makes it possible to evaluate bone union.

Assessment of distraction callus in rabbits by monitoring of the electrical impedance of bone

Background and purpose Evaluation of distraction callus is important for determination of the optimal time for removal of external fixation. We attempted to determine whether there might be a relationship between the electrical impedance of bone and callus maturation, with a view to using impedance as a way of knowing when to remove a fixator. Methods We applied an external lengthener to the right tibia of 24 rabbits and performed distraction at 1 mm/day for 10 days. Radiographs were taken and measurement of overall impedance between fixation pins was performed weekly after distraction. At weeks 2, 4, 6, and 8 after distraction (n = 6 each), resistivity of the bone to electrical conductivity was measured before killing. Cross-sectional area of the conduction pathway in callus and maximum bending stress were measured after excision of the tibia. Results The overall impedance increased statistically significantly from 1 to 6 weeks after completion of distraction. The resistivity of bone decreased over 4 weeks and the cross-sectional area of callus decreased significantly over 6 weeks, while the maximum bending stress increased significantly over the same time. We observed a negative correlation between the cross-sectional area of callus and maximum bending stress. Interpretation The impedance values, which are related to changes in electrical conductivity and the conduction pathway, increased due to the changes in the cross-sectional area of callus, despite the reduction in bone resistivity. Since the cross-sectional area of callus was correlated with maximum bending stress and the impedance values increased with the callus-remodeling process, we suggest that temporal increases in overall impedance reflect callus maturation.

Experience of bone bridge resection and bone wax packing for partial growth arrest of distal tibia.

Two patients with a partial growth arrest of the distal tibia were treated by bone bridge resection and bone wax packing technique. Their average age at the time of surgery was 7 years, both had been injured in an accident, and each had been treated with percutaneous pinning and a plaster cast. Unfortunately, partial growth arrest of the distal tibia occurred, and the ankle varus deformity gradually progressed. About 1 year after initial treatment, bone bridge resection and bone wax packing were performed. The average follow-up period was 80 months. There was no reformation of the bone bridge or recurrence of deformity, and gradual improvements in clinical and radiographic findings were observed. Although fat is typically used as an interpositional material after bone bridge resection, there are problems with its use, including a lack of hemostasis and the absence of intrinsic stability. Bone wax is readily available and commonly used in medical applications to control bleeding. It is considered a useful plug, it is inexpensive, and it is not associated with complications.

Assessment of lateral subluxation in Legg-Calvé-Perthes disease: a time-sequential study of magnetic resonance imaging and plain radiography.

Lateral subluxation of the femoral head is one of the poor prognostic factors of Legg–Calvé–Perthes disease. The aim of this study was to investigate the cause of lateral subluxation of the femoral head on the basis of the changes over time on MRI. Twenty-four patients with unilateral Legg–Calvé–Perthes disease were analyzed retrospectively. Lateral subluxation was measured as the tear drop distance on radiographs. We focused on joint fluid, medial articular cartilage thickening, and abnormal lesion on MRI. Lateral subluxation continued significantly in patients with poor results. Among the MRI findings, the presence of an abnormal lesion was associated significantly with the continuous lateral subluxation.

Acetabular anteversion angle from early stage of Perthes disease to adolescence.

OBJECTIVE This study aimed to assess acetabular anteversion angle (AAA) from the early stage of Perthes disease to adolescence. METHODS Twenty-five patients treated conservatively were examined. Changes in AAA from initial to final measurement were compared between the two groups (G-group: Stulberg classes I and II; P-group: classes III and IV). RESULTS In the G-group, AAA decreased significantly in the affected hip compared with the unaffected hip, whereas AAA decreased in both hips in the P-group. CONCLUSION Acetabular retroversion may occur only in the affected hip or in both hips; in the latter case, the treatment outcome may be poor.

Monitoring of Callus Maturation and Measurement of Resistance Rates Using Bioelectrical Impedance for Patients Treated With an External Fixator

Evaluation of callus maturation and the decision to remove an external fixator depend on radiographic and clinical findings, which are subjective. Callus fracture or recurrent deformity may occur after premature removal of a fixator. The authors applied a technique to measure bioelectrical impedance to assess callus maturation. This study included 27 limbs that underwent deformity correction or callus distraction using a fixator. Mean patient age at the time of surgery was 17.2 years. Overall impedance during callus maturation was measured from after completion of correction or distraction to removal of the fixator. Temporal changes in impedance values were measured, and maximum and final values were compared with initial values. The resistance rates were compared by age (<15 or ≥15 years), correction site (femur or tibia), and treatment method (noncontact or contact). Mean overall impedance increased gradually. Compared with initial values, maximum and final impedance values were 1.21 times and 1.15 times higher, respectively. Resistance rates by age, correction site, and treatment method were significantly higher in patients 15 years and older, in the tibia, and in the contact group, respectively. Overall impedance tended to increase during callus maturation but varied among patients. Therefore, resistance rates were calculated to classify differences for individual patients. Age and treatment method were important predictors of resistance rates. These data by age, correction site, and treatment method, which assume overall impedance from after completion of correction or distraction, can serve as a useful index to determine when a fixator should be removed. [Orthopedics. 2018; 41(1):54-58.].

Modyfied wedge osteotomy for osteoarthritis of elbow secondary to osteochondritis dissecans in adolecent with multiple epiphyseal dysplasia. A case report

Multiple epiphyseal dysplasia (MED) may be complicated by osteochondritis dissecans (OCD), most commonly reported in the knee, but involvement of the elbow is very rare. Optimal treatment for MED-associated elbow OCD and treatment outcome have not been established. This report describes the case of an adolescent male patient with elbow OCD treated by arthroscopic drilling at a previous clinic. Progression of osteoarthritis and radial head subluxation were observed. Resection of the osteophytes and modified wedge osteotomy of the lateral condyle were then performed, and a favorable result was obtained by decompression and sufficient congruency of the radiohumeral joint.

Examination of the Correlation Between Foot Morphology Measurements Using Pedography and Radiographic Measurements

Abstract Pedography provides excellent visualization of the footprint. However, the correlation between the footprint images and radiographic measures has not been thoroughly evaluated. Therefore, the objectives of our study were to examine the correlation between the pedography‐based measures of foot morphology and radiographic measurements and to propose reference values for the diagnosis of flatfoot using footprint imaging. The plantar footprints of 100 right feet were photographed using a pedography standing platform. The sole and arch areas were measured to calculate the footprint index (FPI). The lateral talar–first metatarsal angle (LTM) and calcaneal pitch angle (CP) were measured on standing lateral radiographs, and the talonavicular coverage angle was measured on frontal radiographs. The Pearson moment correlation between the FPI and radiography‐based measures was calculated. The area under the receiver operating characteristic curve was calculated using an LTM of <−4° as the identifying criterion of flatfoot. The sensitivity and specificity of FPI were calculated for LTM values <−4°. The FPI correlated with the LTM (y = −17.964 ± 52.644x, R = 0.588) and CP (y = 9.2304 ± 27.739x, R = 0.659) but not with the talonavicular coverage angle (y = 26.01 ± 15.78x, R = 0.207). The area under the receiver operating characteristic curve was 0.753, with a cutoff FPI of 0.208, yielding a sensitivity of 0.462 and specificity of 0.934 for flatfoot identification. Pedography could provide an easy screening tool for flatfoot, with an FPI cutoff of 0.208, yielding a specificity of 93.4%. &NA; Level of Clinical Evidence: 3

Valgus Slipped Capital Femoral Epiphysis in Patient with Hypopituitarism

Slipped capital femoral epiphysis (SCFE) is a common disease of adolescent and the epiphysis is positioned more posteromedially in relation to the femoral neck shaft with varus SCFE; however, posterolateral displacement of the capital epiphysis, valgus SCFE, occurs less frequently. We report a case of valgus SCFE in a 17-year-old boy with hypopituitarism. After falling down, he experienced difficulty in walking. The radiographs were inconclusive; however three-dimensional computed tomography images showed lateral displacement of the epiphysis on the right femoral head. Valgus SCFE was diagnosed. The patient underwent in situ pinning of both sides. In situ pinning on the left side was performed as a prophylactic pinning because of endocrine abnormalities. At the 1-year follow-up, he could walk without any difficulty and there were no signs of pain. The epiphysis is commonly positioned more posteromedially in relation to the femoral neck shaft with most SCFE, but, in this case, the epiphysis slipped laterally. Differential diagnosis included femoral neck fracture (Delbet-Colonna type 1); however, this was less likely due to the absence of other clinical signs. Therefore, we diagnosed the patient as SCFE. When children complain of leg pain and limp, valgus SCFE that may not be visualized on anteroposterior radiographs needs to be considered.