Low back pain is more common in women than men, yet most studies of intervertebral disc (IVD) degeneration do not address sex differences. In humans, there are sex differences in spinal anatomy and degenerative changes in biomechanics, and animal models of chronic pain have demonstrated sex differences in pain transduction. However, there are few studies investigating sex differences in annular puncture IVD degeneration models. IVD puncture is known to result in progressive biomechanical alterations, but whether these IVD changes correlate with pain is unknown. This study used a rat IVD injury model to determine if sex differences exist in mechanical allodynia, biomechanics, and the relationship between them, six weeks after IVD injury. Procedures were IACUC approved. 24 male & 24 female four-month-old Sprague-Dawley rats underwent a sham or annular puncture injury surgery (n=12 male, 12 female). In injury groups, three lumbar IVDs were each punctured three times with a needle, and injected with tumor necrosis factor-alpha. Mechanical allodynia was tested biweekly using von Frey filaments. Six weeks after IVD injury, rats were euthanized and motion segments were dissected for non-destructive axial tension-compression and torsional rotation biomechanical testing. Two-way ANOVA with Bonferroni corrections identified statistically significant differences (p < 0 .05) and correlations used Pearson's coefficient. Annular puncture injury induced a significant increase in mechanical allodynia compared to sham in male but not female rats up to six weeks after injury. There was a significant sex effect on both torque range and torsional stiffness, with males exhibiting greater stiffness and torque range than females. Tensile stiffness, compressive stiffness, and axial range of motion showed no sex difference. Males and females showed similar patterns of correlation between variables when sham and injury groups were analyzed together, but correlations were stronger in males. Most correlations were clustered within testing approach: axial biomechanics negatively correlated, torsional biomechanics positively correlated, and von Frey thresholds positively correlated. Surprisingly, mechanical allodynia did not correlate with any biomechanics after injury, and the axial and torsional biomechanics showed little correlation. This study demonstrates that males and females respond to IVD injury differently. Given the absence of correlation between pain and biomechanics, pain cannot be attributed completely to biomechanical changes. This may explain why spinal fusion surgery, an intervention limited to the spine, has produced inconsistent results and is controversial for patients with low back pain. Thus, in addressing low back pain, we must consider both spinal tissues and the nervous system. Further, the limited correlation between axial and torsional biomechanics indicates that IVD injury may have distinct effects on nucleus pulposus and annulus fibrosus. Biomechanics did not differ between sham and injury at week six, suggesting healing after injury. It remains possible that acute biomechanical changes may initiate chronic pain pathogenesis. We conclude that the observed sex differences demonstrate the need for inclusion of both males and females in IVD injury and pain studies, and suggest that males and females may require different treatments for conditions that appear similar

As treatments of knee osteoarthrosis are continually refined, increasingly sophisticated methods of evaluating their biomechanical function are required. Whilst TKA shows good preoperative pain relief and survivorship, functional outcomes are sub-optimal, and research focus has shifted towards their improvement. Restoration of physiological function is a common design goal that relies on clear, detailed descriptions of native biomechanics. Historical simplifications of true biomechanisms, for example sagittal plane approximation of knee kinematics, are becoming progressively less suitable for evaluation of new technologies. The patellar tendon moment arm (PTMA) is an example of such a metric of knee function that usefully informs design of knee arthroplasty but is not fully understood, in part due to limitations in its measurement. This research optimized PTMA measurement and identified the influence of knee size and sex on its variation. The PTMA about the instantaneous helical axis was calculated from optical tracked positional data. A fabricated knee model facilitated calculation optimization, comparing four data smoothing techniques (raw, Butterworth filtering, generalized cross-validated cubic spline-interpolation and combined filtering/interpolation). The PTMA was then measured for 24 fresh-frozen cadaveric knees, under physiologically based loading and extension rates. Sex differences in PTMA were assessed before and after size scaling. Large errors were measured for raw and interpolated-only techniques in the mid-range of extension, whilst both raw and filtered-only methods saw large inaccuracies at terminal extension and flexion. Combined filtering/interpolation enabled sub-mm PTMA calculation accuracy throughout the range of knee flexion, including at terminal extension/flexion (root-mean-squared error 0.2mm, max error 0.5mm) (Figure 1). Before scaling, mean PTMA throughout flexion was 46mm; mean, peak, and minimum PTMA values were larger in males, as was the PTMA at terminal flexion, the change in PTMA from terminal flexion to peak, and the change from peak to terminal extension (mean differences ranging from 5 to 10mm, p<0.05). Knee size was highly correlated with PTMA magnitude (r>0.8, p<0.001) (Figure 2). Scaling eliminated sex differences in PTMA magnitude, but peak PTMA occurred closer to terminal extension in females (female 15°, male 29°, p=0.01) (Figure 3). Improved measurement of the PTMA reveals previously undocumented characteristics that may help to improve the functional outcomes of knee arthroplasty. Knee size accounted for two-thirds of the variation in PTMA magnitude, but not the flexion angle at which peak PTMA occurred, which has implications for morphotype-specific arthroplasty and musculoskeletal models. The developed calculation framework is applicable both in vivo and vitro for accurate PTMA measurement and might be used to evaluate the relative performance of emerging technologies. For any figures or tables, please contact the authors directly

Distal radius fractures are the most common upper extremity injury, and are increasingly being treated surgically with pre-contoured volar-locking plates. These plates are favored for their low-profile template while allowing for rigid anatomic fixation of distal radius fractures. The geometry of the distal radius is extremely complex, and little evidence within the medical literature suggests that current implant designs are anatomically accurate. The main objective of this study is to determine if anatomic alignment of the distal radii corresponds accurately with modern volar-locking plate designs. Additionally, this study will examine sex-linked differences in morphology of the distal radius. Segmented CT models of ten female cadaver (mean age, 88.7 ± 4.57 years, range, 82 – 97) arms, and ten male cadaver (mean age, 86 ± 3.59 years, range, 81 – 91) arms were created. Micro CT models were obtained for the DePuy Synthes 2.4mm Extra-articular (EA) Volar Distal Radius Plate (4-hole and 5-hole head), and 2.4mm LCP Volar Column (VC) Distal Radius Plate (8-hole and 9-hole head). Plates were placed onto the distal radii models in a 3D visualization software by a fellowship-trained orthopaedic hand surgeon. The percent contact, volar cortical angle (VCA), border and overlap of the watershed line (WSL) were measured. Both sexes showed an increase in the average VCA measure from medial to lateral columns which was statistically significant. Female VCA ranged from 28 – 36 degrees, and 38 – 45 degrees for males. WSL overlap ranged from 0 – 34.7629% for all specimens without any statistical significance. The average border distance for females was 2.58571 mm, compared to 3.52411 mm for males, with EA plates having a larger border than VC plates. The border distances had statistically significant differences between the plate types, and was approaching significance between sexes. Lastly, a maximum percent contact of 21.966 % was observed in specimen F4 at a 0.3 mm threshold. No statistical significance between plate or sex populations was observed. This study investigated the incoherency between the volar cortical angle of the distal radius, and the pre-contoured angle of volar locking plates. It was hypothesized that if the VCA measures between plate and bone were unequal then there would be an increase in watershed line overlap, and decrease in percent contact between the surfaces. Our results agreed with literature, indicating that the VCA of bone was larger than that of the EA and VC pre-contoured plates examined in this study. With distal radius fracture incidences and prevalence on the rise for elderly female patients, it is a necessity that volar locking plates be re-designed to factor in anatomical features of individual patients with a particular focus on sex differences. New designs should focus on providing smaller head sizes that are more accurately tailored to the natural contours of the volar distal radius. It is recommended that future studies incorporate expertise from multiple surgeons to diversify and further understand plate placement strategies

Introduction. For anatomical reconstruction in shoulder arthroplasty, it is important to understand normal glenohumeral geometry. Unfortunately, however, the details of the glenohumeral joint in Asian populations have not been sufficiently evaluated. There is a racial difference in body size, and this difference probably results in a difference in glenohumeral size. The purpose of this study was to evaluate three-dimensional geometry of the glenohumeral joint in the normal Asian population and to clarify its morphologic features. Methods. Anthropometric analysis of the glenohumeral joint was performed using computed tomography scans of 160 normal shoulders from healthy volunteers in age from 20 to 40 years. Using OsiriX MD, Geomagic Studio, and AVIZO software, the dimensions of humeral head width, humeral head diameter, glenoid height, glenoid width, and glenoid diameter were analyzed three-dimensionally (Figure 1). In diameter analyses, the humeral head was assumed to be a sphere and the glenoid was to fit a sphere (Figure 2–3). Sex differences in height, humeral length, humeral head width, humeral head diameter, glenoid height, glenoid width, and glenoid diameter were compared using Mann-Whitney U tests. The correlations between sides and among the respective parameters in the glenohumeral dimensions were evaluated with Spearman rank correlation tests. The significance level was set at 0.05 for all analyses. Results. Average height and humeral length of the volunteers were 164.7 ± 9.7 cm and 29.1 ± 1.8 cm respectively. The normal Asian glenohumeral joint has average humeral head width of 41.4 ± 3.7 mm, humeral head diameter of 42.9 ± 3.6 mm, glenoid height of 31.5 ± 2.8 mm, glenoid width of 23.1 ± 2.4 mm, and glenoid diameter of 62.0 ± 6.8 mm. The humeral head and glenoid were significantly larger in males than in females (p<0.001 in all analyses). The average radius difference between the glenoid and the humeral head was 9.6 ± 2.8 mm, and there was no sex difference (p=0.359). The average ratio of the glenoid radius to the humeral head radius was 144.9% ± 12.2%, and the ratio was significantly larger in females than in males (p=0.026). The glenohumeral size was well correlated between the two sides, and there were direct correlations among the heights, humeral length, humeral head size, and glenoid size (p<0.001 in all analyses). Conclusions. The present study revealed that the values of glenohumeral dimensions were uniform in both males and females with a strong correlation between the dominant shoulder and the nondominant shoulder. Since there are direct correlations among height, humeral length, and the size of the glenohumeral joint, we can also predict the glenohumeral size of patients from their respective heights. The present results would be useful to determine the size of implants and to improve clinical outcomes of shoulder arthroplasty for glenohumeral joints of Asian patients. The size of the Asian glenohumeral joint was obviously smaller than that reported in the past literature including black and Caucasian populations. Some shoulder prostheses that are designed in Europe or America and are widely used worldwide could be oversized for small females

Aim. This study aimed to evaluate the impact on length of hospital stay from dedicated infectious diseases input for orthopaedic infection patients compared to sporadic infection specialist input. Method. We conducted an observational cohort study of 157 adults with orthopaedic infections at a teaching hospital in the UK. The orthopaedic infections included were: osteomyelitis, septic arthritis, infected metalwork and prosthetic joint infections, and adults were aged 18 years or more. Prior to August 2016, advice on orthopaedic infection patients was adhoc with input principally from the on-call infectious diseases registrar and phone calls to microbiology whereas after August 2016 these patients received regular input from dedicated infectious diseases doctor(s). The dedicated input involved bedside reviews, medical management, correct antimicrobial prescribing, managing adverse drug reactions, increased use of outpatient parenteral antimicrobial therapy (OPAT) services especially self-administration of intravenous antibiotics and shared decision-making for treatment failure, whilst remaining under orthopaedic team care. Orthopaedic patients operated on for management of their infection between 29/8/16 and 15/3/17 were prospectively identified and orthopaedic operation records were used to retrospectively identified patients between 29/8/15 and 15/3/16. The length of stay was compared between the 2 groups. Results. There were 83 patients in the dedicated infectious diseases input group (dedicated group) and 74 patients in the sporadic infection specialist input group (sporadic group). The dedicated group were significantly younger: median 58 years versus 69years (p<0.001), and there was a trend to significant differences in the breakdown of diagnosis (p=0.06), but no significant sex difference. The median length of stay for the sporadic group was 20 days (interquartile range (IQR) 13–29 days) compared to 14 days (IQR 9–27 days) for the dedicated group, with a trend to significance (p=0.06) but no effect from age or diagnosis. Our hospital values one day in hospital at £864, therefore over the 6.5 months trial period of the dedicated infectious diseases input there was a cost saving of £430,272 (£864 × 6 days × 83 patients). Conclusions. Dedicated infectious diseases input would be expected to improve patient care but by additionally reducing median length of stay for orthopaedic infection patients, this encourages investment to achieve both. In this era of increased scrutiny of health budgets demonstrating value for money, not just improved quality of patient care, is essential

Background. Total Hip Arthroplasty (THA) has long been the standard treatment for cases in which non-surgical alternatives have failed to improve pain and function in hip osteoarthritis (OA) patients. Outcomes from THA have improved over time with better surgical techniques and improved implant designs. While conventional neck-sacrificing implants have been associated with favorable outcomes, there is evidence to suggest biomechanical advantages of newer, femoral neck-preserving short-stem implants, including the Corin MiniHip. However, there is a still a gap of knowledge regarding the potential benefits of the MiniHip stem over conventional neck-sacrificing stems in regards to patient-reported outcomes (PROs). In this study, we investigated the differences between a neck-sacrificing stem design and neck-preserving short-stem design (MiniHip, Corin Inc.) arthroplasty concerning PROs, and considering the known features of the short stem design, we hypothesized that MiniHip THA would be associated with improved PROs in comparison to a neck-sacrificing implant system. We further sought to investigate gender effects related to MiniHip or conventional stem surgery. Methods. Neck-sacrificing implant patients (n=90, age 57±7.9 years, female=58, male=32) and a matched (matching criteria: follow-up period, BMI, age) cohort group of MiniHip patients (n=105, age 55.16±9.88 years, female: 25, male: 80) reported both pre-operative and post-operative Hip disability and Osteoarthritis Outcome Scores (HOOS) at a minimum interval of 6 months post-operatively and up to three years postoperatively. We applied MANCOVA analysis to compare patient-reported outcome subscores from each group using follow-up period as a covariate and employing gender as an additional grouping factor to evaluate gender effects. Statistical significance was set at α=0.05 and Bonferroni corrections were applied to account for multiple comparisons. Results. There was a main effect of time, showing that all HOOS subscores of both groups increased significantly after surgery (p<0.001). There was a main effect of surgery for subscores Symptoms (p=0.038), ADL (p=0.046), and Sports and Recreation (p=0.039). There was a gender effect only for the subscore Symptoms (p=0.007). There were significant time by surgery interactions for HOOS subscores Symptoms (p=0.002), Pain (p=.009), Sports and Recreation (p=0.004), and QOL (p<0.001) subscores. We also observed a significant time by gender interaction effect for all HOOS subscores (p<0.001). Discussion. The interaction effects regarding most HOOS subscores and surgery/implant type indicate an advantage of MiniHip surgery regarding post-operative reported outcomes. The observed results may be due to previously described improved physiological loading and native hip structure preservation with neck-preserving short-stem designs. While longer-term studies are required for further investigation, evidence suggests the MiniHip may provide a significant benefit to primary THA patients. The additional gender/time interaction effect observed in our study highlights the necessity to consider potential sex differences regarding both the potential/expected improvement in PROs from THA and the requirement to account for such differences when designing osteoarthritis outcome studies based on PROs

Background. Glenoid baseplate fixation for reverse shoulder arthroplasty relies on the presence of sufficient bone stock and quality. Glenoid bone may be deficient in cases of primary erosions or due to bone loss in the setting of revision arthroplasty. In such cases, the best available bone for primary baseplate fixation usually lies within the three columns of the scapula. The purpose of this study was to characterise the relationship of the three columns of the scapula independent of glenoid anatomy and to establish the differences between male and female scapular anatomy. Methods. Fifty cadaveric scapulae (25 male, 25 female) were analysed using CT-based imaging software. The surface geometries of the coracoid, scapular spine and inferior scapular column were delineated in the sagittal plane. A linear best-fit line was drawn to establish the long axis of each column independent of the glenoid. The width of the glenoid was measured and points marked at the midpoint of each measurement. A best-fit line starting at the supra glenoid tubercle passing through the midpoints was chosen as the superior inferior (SI) axis of the glenoid. An orthogonal plane to the scapular plane was developed parallel to the glenoid face. The axis representing each of the three columns of the scapula and the SI axis of the glenoid, were projected onto this plane. The relationship between each column was analysed with respect to each other and with respect to the SI glenoid axis. Thus, measurements obtained gave the relationships of the three columns of the scapula (independent of the glenoid) and their relationships to the long axis of the glenoid (dependant on the glenoid). Comparisons were made between males and females using the independent t-tests. Results. The mean angle between the scapular spine and the coracoid column was 93±13° with no significant difference between males (91±15°) and females (95±10°) (p=0.29). The angle between the inferior scapular column and the scapular spine was 6.5° greater (p=0.03) in females (134±10°) than in males (128±11°). Similarly, the angle between the inferior scapular column and the coracoid column was 11° greater (p=0.009) in males (141±15°) than in females (130±12°). No significant sex difference was found between the acromion and inferior scapular pillar with respect to the SI glenoid axis. However, the female coracoid was found to be more horizontal than the male coracoid in relation to the SI axis of the glenoid (p=0.037). Conclusion. This study demonstrates that the relationship between the scapular spine and the coracoid column is independent of sex. However, sex has significant effects on the positions of the scapular spine and coracoid columns with respect to the inferior scapular column. The inferior scapular column is noted to be positioned more anterior (closer to the coracoid) in females than in males. Sex variations may be important when directing screws for baseplate fixation in bone deficient glenoids undergoing reverse shoulder arthroplasty

Background. Humeral version is the twist angle of the humeral head relative to the distal humerus. Pre-operatively, it is most commonly measured referencing the transepicondylar axis, although various techniques are described in literature (Matsumura et al. 2014, Edelson 1999, Boileau et al., 2008). Accurate estimation of the version angle is important for humeral head osteotomy in preparation for shoulder arthroplasty, as deviations from native version can result in prosthesis malalignment. Most humeral head osteotomy guides instruct the surgeon to reference the ulnar axis with the elbow flexed at 90°. Average version values have been reported at 17.6° relative to the transepicondylar axis and 28.8° relative to the ulnar axis (Hernigou, Duparc, and Hernigou 2014), although it is highly variable and has been reported to range from 10° to 55° (Pearl and Volk 1999). These studies used 2D CT images; however, 2D has been shown to be unreliable for many glenohumeral measurements (Terrier 2015, Jacxsens 2015, Budge 2011). Three-dimensional (3D) modeling is now widely available and may improve the accuracy of version measurements. This study evaluated the effects of sex and measurement system on 3D version measurements made using the transepicondylar and ulnar axis methods, and additionally a flexion-extension axis commonly used in biomechanics. Methods. Computed tomography (CT) scans of 51 cadaveric shoulders (26 male, 25 female; 32 left) were converted to 3D models using medical imaging software. The ulna was reduced to 90° flexion to replicate the arm position during intra-operative version measurement. Geometry was extracted to determine landmarks and co-ordinate systems for the humeral long axis, epicondylar axis, flexion-extension axis (centered through the capitellum and trochlear groove), and ulnar long axis. An anatomic humeral head cut plane was placed at the head-neck junction of all shoulders by a fellowship trained shoulder surgeon. Retroversion was measured with custom Matlab code that analysed the humeral head cut plane relative to a reference system based on the long axis of the humerus and each elbow axis. Effects of measurement systems were analyzed using separate 1-way RM ANOVAs for males and females. Sex differences were analyzed using unpaired t-tests for each measurement system. Results. Changing the measurement reference significantly affected version (p<0.001). The ulnar axis method consistently resulted in higher measured version than either flexion-extension axis (males 9±1°, females 14±1°, p<0.001) or epicondylar axis (males 8±1°, females 12±1°, p<0.001). See Figure 1. Version in males (38±11°) was 7° greater than females (31±12°) when referencing the flexion-extension axis (p=0.048). Conclusion. Different measurement systems produce different values of version. This is important for humeral osteotomies; if version is assessed using the epicondyles pre-operatively and subsequently by the ulna intra-operatively, then the osteotomy will be approximately 10° over-retroverted. For any figures or tables, please contact authors directly (see Info & Metrics tab above).

Objective. The aim of this study was to evaluate the shape of patella relative to the femoral epicondylar axis and to find sex differences. Materials and methods. Computed tomography (CT) images of 100 knees with tibiofemoral osteoarthritis in 100 patients were prospectively collected. All patients were diagnosed as varus-type osteoarthritis with no destructive patellar deformity. Fifty patients were male and 50 female. The average male age was 70.8±14.6 (mean ± SD) years and the average female age was 73.3±6.7 years. Forty nine knees were right and 51 knees were left. The average height of males was 162.6±7.4 cm and that of females 149.6±5.7 cm. Males were significantly taller than females. The CT scan was performed with 2mm-interval slices in the vertical plane to the long axis of femoral shaft. Every CT image was examined to determine the maximum distance between the medial and lateral femoral epicondyle (inter-epicondylar distance, IED) along the epicondylar axis. The maximum patellar width and thickness were also measured at the image which had these maximum distances, while patellar cartilage thickness in anteroposterior diameter was not measured in this study. For evaluating the patellar size, each measured value was divided by IED and calculated each ratio. The ratio of patellar width to patellar thickness was also calculated. All parameters were compared between males and females. Statistical software Statview ver.5.0 (SAS Institute Inc.) was used for all analyses with significance being set at the 5% level. Results. Measured values are presented on Table 1. The average IED, patellar width and patellar thickness of males were all significantly larger than those of females. As shown in Table 2, by contrast, each ratio to IED was almost the same between the sexes and there were no significant differences. The ratio of patellar width to patellar thickness was 46.7±2.6% in males and 46.6±2.9% in females. Discussion. Although some studies have assessed the actual measurement values of patella, no prior study, to our knowledge, has morphologically evaluated the patella relative to the femur. This is the first study to investigate the configuration and location of patella relative to femoral epicondylar axis. Our results showed the configuration of patella relative to the femoral epicondylar axis was the same between sexes. The patellar width is approximately 56% and TGD is approximately 39% of IED. The most common complications after the surgery are related to patellofemoral problems. The ideal thickness of the resurfaced patella has not been clearly investigated. Patellar disabilities are associated with both decreased and increased patellar thickness— a thin patella could lead to anteroposterior patellar instability and a thick patella could increase the risk of stiffness of the knee and patellar subluxation. Therefore, it is desirable to restore the original patellar thickness during surgery. The results of current study showed that the ratio of patellar width to the patellar thickness was about 47%, which is useful to determine the thickness of patella during surgeries for severely damaged knees or revision surgeries

Aims

Physician burnout and its consequences have been recognized as increasingly prevalent and important issues for both organizations and individuals involved in healthcare delivery. The purpose of this study was to describe and compare the patterns of self-reported wellness in orthopaedic surgeons and trainees from multiple nations with varying health systems.