Effect of a computer-assisted navigation system on the lag screw placement accuracy of less experienced surgeons.

BACKGROUND: Femoral trochanteric fracture is treated by osteosynthesis using an angle-fixed implant. Lag screw cut-out is a postoperative complication, and a tip-apex distance (TAD) of 20 mm or shorter is recommended to prevent it. The use of a navigation system for lag screw placement has been reported, but the use and non-use of navigation systems by less experienced surgeons has not been assessed. The objective of this study was to retrospectively investigate the usefulness of a navigation system for short femoral nailing. METHODS: The subjects were 101 patients with femoral trochanteric fracture treated by osteosynthesis at our hospital between May 2017 and December 2018 (male, 14; female, 87; mean age, 84.7 years; navigation use group, 55; non-navigation use group, 46). The patients were divided into four groups: groups treated by less experienced surgeons with (Navigation-Young surgeon [NY] group, n = 35) and without (Manual-Young surgeon [MY] group, n = 23) the use of a navigation system; and groups treated by experienced surgeons with (Navigation-Aged surgeon [NA] group, n = 20) and without (Manual-Aged surgeon [MA] group, n = 23) the use of a navigation system. TAD (mm) and operative time (min) were compared. RESULTS: The TAD was significantly longer in the MY group than in the NY group. The percentages of patients with 10-20 mm TAD were as follows: NY group, 94.3%; MY group, 65.2%; NA group, 100%; MA group, 100%. The mean operative time was significantly longer in the NY group than in the MA group, but no significant difference in mean operative time was noted between the NY and MY groups or between the NA and MA groups. CONCLUSIONS: A computer-assisted navigation system improves the accuracy of lag screw placement performed by less experienced operators without increasing the operative time.

Investigating interindividual variations in cortical bone quality: analysis of the morphotypes of secondary osteons and their population densities in the human femoral diaphysis.

Osteons are the primary sites of cortical bone lesions. However, many aspects of osteon microstructure remain poorly understood. This study aimed to explores interindividual differences in the osteon morphotype distributions in the human femoral diaphysis by evaluating the secondary osteon distributions in samples from human femurs. Two anonymized bone fragments from two modern Japanese femurs were examined. Twelve continuous transverse femoral diaphysis specimens were prepared from each fragment. Imaging examinations were conducted using a circularly polarized light microscope, and cross-sectional images were rendered using graphical synthesis software. Osteons in the images were identified as either bright-type osteons, dark-type osteons, or an others type. The two femurs were compared, and the secondary osteon morphotype distributions in different regions of their cross-sections were analyzed. When the two femurs were compared, significant differences in osteon density were observed in some regions and cross-sections. The dark-type osteon presence was strongest in the anterior and posterior regions of the femurs. The analytical method used in this study was found to be able to evaluate osteon microstructure. The results suggest that examining additional specimens and analyzing the biomechanical underpinnings of interindividual differences in osteon distribution patterns may help to improve our understanding of osteon microstructure.

Diversity in intracortical remodeling in the human femoral bone: A novel view point with the morphological analysis of secondary osteons.

INTRODUCTION: In humans, intracortical bone remodeling is performed by a basic multicellular unit (BMU) composed of osteoclasts and osteoblasts penetrating through cortical bones. As a result, secondary osteons and their boundaries, cement lines, can be observed on the transverse section. There have been few reports mention whether there is diversity within a single individual and on the relevance to bone remodeling. The purpose of this study is to investigate the morphological diversity of secondary osteons in human femoral bone and to examine the relationship with bone remodeling. MATERIAL AND METHODS: First of all, we developed an original method to get the cross-sectional images of the cortical bones around the whole circumference for the purpose of evaluating the morphology of the secondary osteon exhaustively. Then, a total of ten cross-sectional slices from one right human femoral bone of male were prepared and stained with this method. The osteon population density and complexity of cement lines in osteons were evaluated in detail. RESULTS: Within this femoral bone, the osteon population density was significantly higher in the periosteal side and in the posterior area. Conversely, the cement line density and the osteon complexity were higher in the endosteal side; the proportion of complexed osteon significantly increased from the periosteal side toward the endosteal side. DISCUSSION: The results suggested that there were diversities in osteon population densities and osteon morphological pattern within one human femoral bone. It seemed that the BMUs ran to avoid the existing regions of osteon in the periosteal sides and to overlap the existing osteon in the endosteal sides. This seemed to be one of the novel viewpoints in the morphological analysis of secondary osteons. It might be better for the orthopedic surgeons to be aware that the osteon distribution in the cortical bone is not uniform.

Epidemiology of Kienböck's disease in middle-aged and elderly Japanese women.

Little research has been done on the prevalence of Kienböck's disease, and there is no consensus on the relationship between Kienböck's disease and negative ulnar variance. The goal of this cross-sectional study was to determine the prevalence of Kienböck's disease in middle-aged and elderly Japanese women and to clarify the relationship between Kienböck's disease and negative ulnar variance. The authors analyzed plain radiographs of both hands in women 40 years and older residing in the community to investigate the prevalence of Kienböck's disease and the relationship between Kienböck's disease and negative ulnar variance. Kienböck's disease was seen in 7 of the 572 participants. In the group with Kienböck's disease, ulnar variance did not differ significantly between affected (0.3 mm; SD, 1.5) and unaffected (0.3 mm; SD, 1.0; P=.285) sides. No significant difference was seen in ulnar variance values between the affected side in the group with Kienböck's disease and the normal group (P=.118). The number or proportion of participants with negative ulnar variance did not differ significantly between the affected side in the group with Kienböck's disease (3 of 7) and the unaffected side in the group with Kienböck's disease (1 of 7; P=.237) and between the affected side in the group with Kienböck's disease and the normal group (111 of 504; P=.189) by chi-square test. The prevalence of Kienböck's disease was 1.2% in middle-aged and elderly Japanese women. Negative ulnar variance is not a contributing factor to Kienböck's disease.

Characterization of individuals with sacroiliac joint bridging in a skeletal population: analysis of degenerative changes in spinal vertebrae.

The aim of this study was to characterize the individuals with sacroiliac joint bridging (SIB) by analyzing the degenerative changes in their whole vertebral column and comparing them with the controls. A total of 291 modern Japanese male skeletons, with an average age at death of 60.8 years, were examined macroscopically. They were divided into two groups: individuals with SIB and those without bridging (Non-SIB). The degenerative changes in their whole vertebral column were evaluated, and marginal osteophyte scores (MOS) of the vertebral bodies and degenerative joint scores in zygapophyseal joints were calculated. SIB was recognized in 30 individuals from a total of 291 males (10.3%). The average of age at death in SIB group was significantly higher than that in Non-SIB group. The values of MOS in the thoracic spines, particularly in the anterior part of the vertebral bodies, were consecutively higher in SIB group than in Non-SIB group. Incidence of fused vertebral bodies intervertebral levels was obviously higher in SIB group than in Non-SIB group. SIB and marginal osteophyte formation in vertebral bodies could coexist in a skeletal population of men. Some systemic factors might act on these degenerative changes simultaneously both in sacroiliac joint and in vertebral column.

Periarticular osteophytes as an appendicular joint stress marker (JSM): analysis in a contemporary Japanese skeletal collection.

OBJECTIVE: The aim of this study was to investigate the possibility that periarticular osteophytes plays a role as a appendicular joint stress marker (JSM) which reflects the biomechanical stresses on individuals and populations. METHODS: A total of 366 contemporary Japanese skeletons (231 males, 135 females) were examined closely to evaluate the periarticular osteophytes of six major joints, the shoulder, elbow, wrist, hip, knee, and ankle and osteophyte scores (OS) were determined using an original grading system. These scores were aggregated and analyzed statistically from some viewpoints. RESULTS: All of the OS for the respective joints were correlated logarithmically with the age-at-death of the individuals. For 70 individuals, in whom both sides of all six joints were evaluated without missing values, the age-standardized OS were calculated. A right side dominancy was recognized in the joints of the upper extremities, shoulder and wrist joints, and the bilateral correlations were large in the three joints on the lower extremity. For the shoulder joint and the hip joint, it was inferred by some distinctions that systemic factors were relatively large. All of these six joints could be assorted by the extent of systemic and local factors on osteophytes formation. Moreover, when the age-standardized OS of all the joints was summed up, some individuals had significantly high total scores, and others had significantly low total scores; namely, all of the individuals varied greatly in their systemic predisposition for osteophytes formation. CONCLUSIONS: This study demonstrated the significance of periarticular osteophytes; the evaluating system for OS could be used to detect differences among joints and individuals. Periarticular osteophytes could be applied as an appendicular joint stress marker (JSM); by applying OS evaluating system for skeletal populations, intra-skeletal and inter-skeletal variations in biomechanical stresses throughout the lives could be clarified.