Position in reverse shoulder arthroplasty

The purpose of this study was to determine the optimal position of the baseplate on the small glenoid of female Japanese. Two sets of 3D scapular models were made according to the CT data of 7 female cadavers. We set two scenarios of the baseplate placement : A and B. In scenario A, the baseplate was placed on the glenoid face centrally in the anteroposterior direction. In scenario B, the baseplate was implanted at the point where the baseplate post was contained within the glenoid vault. Whether or not the baseplate post perforated the scapular neck was recorded. In scenario A, the central post penetrated the scapular neck posteriorly in 5 scapulae. In scenario B, the average distances from the guide pin position to the anterior glenoid rim was 9.7 ± 1.7 mm and the optimal position of the guide pin was 1.9 ± 1.7 mm anterior from the glenoid center. The central post was contained within the scapula without breakage of the cortex. This study demonstrated that shifting the center of the baseplate slightly anterior to the anatomic center is necessary to avoid perforation of the scapular neck in small female Japanese

Intertrochanteric fracture classification

A novel three-dimensional fragment-based classification system based on computed tomography findings was established to characterize femoral intertrochanteric fractures. The intertrochanteric bone fragments were defined as follows : neck, posterior portion of the greater trochanter, anterior portion of the greater trochanter, lesser trochanter, and shaft. Each type of fracture was classified as 2-, 3-, 4-, or 5-fragment according to the number of floating bone fragments. Following the description of the fracture type, each floating bone fragment was appended, with the exception of a fragment involving the shaft. Ninety-five intertrochanteric fractures were classified by the same surgeon. The fractures occurred in 14 men and 81 women with a mean age of 84.7 years. The frequency of each type of fracture was investigated. Thirty-one fractures (32.6%) were 2-fragment and 64 (67.4%) were ≥ 3-fragment. A fragment of the anterior portion of the greater trochanter, which cannot be classified using conventional systems, was included in 29 cases (30.5%). A 5-fragment fracture was detected in two cases (2.1%). Using this fragment-based classification system, intertrochanteric fractures can be evaluated in more detail than is possible using conventional classification systems

Anatomic evaluation of the insertional footprints of the iliofemoral and ischiofemoral ligaments : a cadaveric study

Background: An understanding of the insertional footprints of the capsular ligaments of the hip is important for preserving hip function and stability given the increasing number of minimally invasive hip surgeries being performed under a limited surgical view. However, it is difficult to detect these ligaments intraoperatively and many surgeons may not fully appreciate their complex anatomy. The aims of this study were to quantify the proximal and distal footprints of the iliofemoral ligament (ILFL) and ischiofemoral ligament (ISFL) and to estimate the location of the corresponding osseous landmarks on the proximal femur, which can be detected easily during surgery. Methods: Twelve hip joints from Japanese fresh frozen cadavers were used. All muscle, fascia, nerve tissue, and vessels were removed to expose the intact capsular ligaments of the hip. The length and width of the proximal and distal footprints of the ILFL and ISFL were measured and their relationship to osseous structures was evaluated, including the intertrochanteric line, femoral neck, and lesser trochanter. Results: The mean length of the distal medial arm of the ILFL footprint was 17.9 mm and the mean width was 9.0 mm. The mean length of the distal lateral arm of the ILFL footprint was 23.0 mm and the mean width was 9.7 mm. For the footprint of the medial arm, the insertion was in the distal third of the intertrochanteric line and that of the lateral arm was in the proximal 42% of this line. The mean distance from the lesser trochanter to the footprint of the medial arm was 24.6 mm. The mean length of the distal ISFL footprint was 11.3 mm and the mean width was 6.9 mm. The footprint of the distal ISFL was located forward of the femoral neck axis in all specimens. Conclusions: Understanding the size and location of each capsular ligament footprint in relation to an osseous landmark may help surgeons to manage the hip capsule intraoperatively even under a narrow surgical view. The findings of this study underscore the importance of recognizing that the distal ISFL footprint is located relatively forward and very close to the distal lateral arm footprint

Proximal femoral rotational osteotomy

The Rotational osteotomy for femoral retroversion has been extremely rare despite the known association between femoral neck retroversion, hip pain, and osteoarthritis. Here, we describe a case of femoral neck retroversion for which proximal femoral rotation osteotomy. A 16-year-old boy with a past history of developmental dysplasia of the both hip treated conservatively presented with a complaint of pain in left hips. On physical examination, flexion of the left hip was limited to 90° with terminal pain. Internal rotation was also limited to 10°. Computed tomography (CT) showed -7.1° anteversion of the left femur. We performed rotational osteotomy to increase femoral anteversion because conservative treatment was not effective. The postoperative course was uneventful. At 12 postoperative months, his left hip pain was completely disappeared and femoral anteversion was 34° on CT scans. Retroversion of the femur is a distinct dynamic factor that should be considered in the evaluation of mechanical causes of hip pain. Restoring the normal rotational alignment of the hip resulted in cure of the impingement due to femoral retroversion

Identifying vertebral fractures in the Japanese population using the trabecular bone score : a cross-sectional study

Background: The trabecular bone score (TBS) is reported to be an independent predictor of fracture risk in patients with primary or secondary osteoporosis. However, there have been few reports on its use in the Japanese population. This study aimed to investigate the risk factors for vertebral fracture in the Japanese population and to evaluate the usefulness of TBS. Methods: This cross-sectional study involved 279 patients aged 60–90 years in whom bone mineral density (BMD) was measured by dual-energy X-ray absorptiometry (DXA). TBS was calculated based on the DXA scans. The presence or absence of vertebral fractures was assessed from T11 to L5. The patients were divided into those with vertebral fractures (VF group, n = 104) and those without vertebral fractures (non-VF group, n = 175). Results: Of the 104 patients in the VF group, 75 had 1 vertebral fracture and 29 had 2 or more fractures. The mean TBS was 1.28 in the VF group and 1.35 in the non-VF group (p  1.23). Conclusion: TBS was a significant indicator of vertebral fractures in the Japanese population and might contribute to identifying patients with vertebral fractures, particularly those with osteopenia who need pharmacologic therapy

Rotational and varus–valgus laxity affects kinematics of the normal knee : A cadaveric study

Purpose: The aim of this study was to evaluate the relationship between soft tissue laxity and kinematics of the normal knee using a navigation system. Methods: Fifteen cadaveric knees from 11 fresh frozen whole-body specimens were included in this study. The navigation system automatically recorded the rotation angle of the tibia as the internal–external (IE) kinematics and the coronal alignment of the lower limb as the varus–valgus (VV) kinematics. These measurements were made with the joint in maximal extension, at 10° intervals from 0° to 120° of flexion, and at maximal flexion during passive knee motion. For evaluation of laxity, the examiner gently applied maximum manual IE and VV stress to the knee at 0°, 30°, 60°, and 90° of flexion. Results: The measurements showed almost perfect reliability. The mean correlation coefficient between the intraoperative tibial rotation angle and the intermediate angle of IE laxity was 0.82, while that between the coronal alignment of the lower limb and the intermediate angle of the VV laxity was 0.96. There was a statistically significant correlation between kinematics and laxity at all degrees of knee flexion. Conclusion: The present study revealed that the rotation angle of the tibia was correlated to the intermediate angle of IE laxity at 0°, 30°, 60°, and 90° of knee flexion and the coronal alignment of the lower limb also correlated to the intermediate angle of VV laxity. These findings provide important reference data on soft tissue laxity and kinematics of the normal knee

Intraoperative knee kinematics

The aim of this cadaveric study was to evaluate the intraoperative kinematics of the native knee including two-dimensional translation of the femur using a navigation system. Eight native knees of 4 fresh-frozen whole-body cadavers were used for the study. The kinematics of each knee were analyzed intraoperatively using the navigation system. Although anterior-posterior translation could not be assessed directly, it could be calculated using a formula derived from the parameters in the navigation system. The native knee showed external rotation of the femur in early knee flexion, transient internal rotation in mid flexion, and gradual external rotation in late flexion. There was no marked change in the coronal rotation angle of the mechanical axis during knee flexion. The femoral center moved anteriorly in early knee flexion and posteriorly in late flexion. The distance moved in the medial-lateral direction was relatively smaller than that in the anterior-posterior direction. Two-dimensional translation of the surgical epicondylar axis showed a medial pivot-like motion. In this cadaveric study, the kinematics of the native knee, including two-dimensional translation of the femur, could be satisfactorily assessed intraoperatively using a navigation system. The intraoperative kinematics of the knee can be analyzed in more detail using this methodology

前十字靭帯再建術後のジョギング開始指標における膝伸展筋力体重比の有用性

Background: Quadriceps strength recovery after anterior cruciate ligament (ACL) reconstruction is an important criterion for progress in rehabilitation and return to sports. The purpose of this study was to determine whether quadriceps strength to body weight ratio (QS/BW) is a significant indicator for initiating jogging after ACL reconstruction. Methods: Isokinetic quadriceps strength at 60�/s was measured and a jogging trial was completed 3 months after ACL reconstruction with hamstring tendon autograft in 83 patients (36 male, 47 female; mean age, 26.6 ± 12.4 years). Based on the jogging trial results, patients were assigned to either a successful jogging group (mean velocity ≥ 9 km/h) or an unsuccessful jogging group (mean velocity < 9 km/h). The association between QS/BW and successful jogging after surgery was investigated by multivariate logistic regression analysis and the cut-off value was determined by receiver operating characteristic analysis. Results: Forty-four patients (53.0%) were assigned to the successful jogging group and 39 (47.0%) to the unsuccessful jogging group. QS/BW was independently associated with initiating jogging 3 months after surgery. The cut-off value of QS/BW for successful jogging was 1.45 Nm/kg (area under the curve = 0.94; sensitivity = 88.6%, specificity = 87.2%). All of the patients who initiated jogging with QS/BW of > 1.45 Nm/kg at 3 months returned to sports without recurrence or contralateral injury by 10 months after surgery. Conclusions: QS/BW is a significant indicator for safely initiating jogging 3 months after ACL reconstruction. The cut-off value of QS/BW for initiating jogging was 1.45 Nm/kg

Effect of Hydrogen Gas Pressure on the Mechanical Properties of Low Alloy Steel for Hydrogen Pressure Vessels

ABSTRACT To provide engineering data useful in design, manufacture and operation of hydrogen storage vessels in hydrogen refueling stations, fatigue test machine equipped with highpressure hydrogen autoclave was introduced. The effect of steel&apos;s strength level, temperature effect, fracture toughness and pressure effect were evaluated in gaseous hydrogen environment. When steel&apos;s strength level exceeds around 930MPa to 1000MPa, the elongation and notch tensile properties deleteriously degraded. The elongation reduction by the effect of hydrogen increased with lowering the temperature. The same sensitivity to temperature on crack growth behavior was observed. However, it was shown that the gaseous hydrogen environment only affect the slow stable crack growth but did not affect the critical flaw growth of the steel at low temperature, i.e. fast fracture. The pressure dependence of notch tensile strength ranging from 0.1MPa to 75MPa hydrogen pressure shows approximately 1/2 power dependence

Effect of baseplate position on locking screws

Introduction : Superior screw insertion in reverse shoulder arthroplasty (RSA) carries the potential risk of suprascapular injury. The purpose of this study was to evaluate how the baseplate position affects the superior screw position and length in RSA. Methods : Three-dimensional (3D) computer simulation models of RSA were established using computed tomography data of baseplates with superior and inferior screws and 3D scapular models from 10 fresh cadavers. Superior screw position, the distance from the superior screw hole to the suprascapular notch, and the screw lengths were measured and compared among various baseplate positions with two inferior tilts (0 and 10 degrees) and three rotational patterns (11–5, 12–6, and 1–7 o’clock in the right shoulder). Results : For the 1–7 o’clock / inferior tilt 0 degrees baseplate, the superior screw located anterior to the SS notch in all shoulders, the distance to the SS notch was the longest (12.8 mm), and the inferior screw length was the shortest (23.1 mm). Conclusion : Although there is a concern of a short inferior screw length, initial fixation using a baseplate with 1–7 o’clock rotation and an inferior tilt of 0 degrees appears preferable for SS nerve injury prevention during superior screw insertion