Background

The knee joint morphology varies according to gender and morphotype of the patients.

As for the number of patients who requires total knee arthroplasty (TKA), Asian-Pacific countries will be the most important market. However, due to the paucity of anthropometric data on the proximal tibia in this population, many prostheses designed for Caucasian knees have been introduced without specific modification.The aim of the current study was to analyze the geometry of the proximal tibia to design the optimum component for the Japanese population.

Anthropometric data on the proximal tibia of 100 knees in 80 patients undergoing TKA was obtained. Briefly, anterior-posterior (AP) and medial-lateral (ML) lengths were measured with a combination of two different methods, namely on the computed tomography (CT) images obtained preoperatively and intraoperative direct measurement on tibial resection surface. Reproducible measurement was possible only when the intraoperative measurement was combined with the corresponding CT images while the direction of measurements being aligned to the epicondylar axis of the femur.

It was shown that smaller components with an ML of around 60 mm were rarely required. Tibial component size variation should focus on an ML length of 65 to 75 mm because 76 of 100 knees (76 %) fell into this size range. When the subjects were confined to women, 70 of 77 knees (91%) were included in this size range. The intraoperative AP to ML ratio had a negative correlation with the ML length (r = −0.412, P < 0.0001) indicating that bigger knees were shallower in the AP direction. The size variation of currently popular pros-theses were not in accordance with the geometry of the tibial resection surface shown in this study.

The results of this study applied to a cross-section of the Japanese population can be used by manufacturers to create a prosthesis suitable for most of the Asian-Pacific population.

Background

Although there are predictive equations that estimate the total fat mass obtained from multiple-site ultrasound (US) measurements, the predictive equation of total fat mass has not been investigated solely from abdominal subcutaneous fat thickness. Therefore, the aims of this study were; (1) to develop regression-based prediction equations based on abdominal subcutaneous fat thickness for predicting fat mass in young- and middle-aged adults, and (2) to investigate the validity of these equations to be developed.

Introduction & aims. Different racial groups show variations in femoral morphometry. Femoral anteroposterior measurement and mediolateral measurement are key variables in designing femoral implant for TKR. Their aspect ratio determines the shape and mediolateral sizing for the proper patellofemoral tracking and uniform stress distribution over the resected distal femoral surface. Method. We reviewed the current literature in December 2013 in common medical databases including the Cochrane Library, PubMed and Medline. Keywords included combinations of: Anthropometry, Knee, Arthroplasty, Femur, Morphometry, Geometry. We selected papers including femoral morphometric data collected from populations of different ethnic origins. Papers covered populations in the USA, China, Germany, Thailand, Korea, India, Japan and Malaysia. Results. We have analysed femoral morphometry variables among different ethnic groups from the available data. Gross size of the resected femur can be defined in terms of antero-posterior (AP) and medio-lateral (ML) dimensions, an in the aspect ratio of femoral medio-lateral to femoral antero-posterior dimensions (fML/fAP). The Korean population showed the least value of fAP among all the groups, followed by Thai, Japanese, Indian, Malaysian and Chinese showing the increasing order among the sub-groups of Asian Population. American population shows the next higher fAP measurements from Asian population. German follows, and Arab quantify the largest value of this femoral anthropometric variable. fML varies by huge difference among male and female data in all populations. Thai, Indian, Malaysian, Arab, Japanese, Korean, German, Chinese and American; this sequence is the increasing order of fML. More trapezoid-shaped and narrower ML, this variation in female group leads to over-hang the implant for a given fAP. Generally, the aspect ratios are measured higher in these smaller female knees, and lower in larger male knees. Conclusions. Anthropometric data measuring distal femoral segment in different ethnic groups shows that the Asian population requires custom-fit implant design based on the morphological data. It would be more appropriate to introduce several medio-lateral options in sizing the implant for given antero-posterior dimensions

Introduction. Maximizing efficiency in total knee replacement surgery is desirable and one of the key aspects is optimum utilization of available theatre time allocation. The level of complexity of the pathology is often one of the determinants of the length of operative time. Body mass index (BMI) has also been positively correlated with operative time. However, two patients with the same BMI but different body habitus (central obesity vs generalized obesity) may present different challenges during surgery. An index focusing on the anthropometry of the lower limb (supra-patella index SPI) has been proposed and we hypothesize that it correlates more closely with operative time than BMI. Method. BMI and SPI were determined in all patients recruited into a prospective trial of a specific knee implant. All patients were operated on by one of two surgeons in a standardized manner. Data including operative time and tourniquet time were determined. Results. Data for BMI was available on 50 patients and 46 patients had SPI values. The mean BMI was 34, 3 (sd 7.6) and 74% of patients were obese. The mean SPI was 2, 3 (sd 3.2). Both the BMI and SPI correlated with operative time and tourniquet time using the Spearman rank-order correlation coefficient. The BMI correlated marginally better with the operative time and the SPI correlated marginally better with the tourniquet time. Conclusion. Both BMI and SPI correlated with operative time. Both indices can be used as predictors of operative time. ONE DISCLOSURE

Introduction. In a previous study of subjects with no history of lower extremity injury or disease we found a linear relationship between body weight and peak hip, knee, and ankle joint forces during the stance phase of gait. To investigate the effect of total knee arthroplasty (TKA) on forces in the operated joints as well as the other joints of the lower extremities, we tested TKA subjects during gait and performed inverse dynamics analyses of the results. Materials and Methods. TKA subjects (3 M, 1 F; 58 ± 5 years; body mass index range (BMI): 26–36 kg/m. 2. ) participated in this investigation following institutional review board approval and informed consent. One subject had bilateral knee replacement. Each patient received the same implant design (4 PS, 1 CR). Data from previously tested control subjects (8 M, 4 F; 26 ± 4 years; BMI: 20–36 kg/m. 2. ) were used for comparison. Retro-reflective markers were placed over bony landmarks of each subject. A nine-camera video-based opto-electronic system was used for 3D motion capture as subjects walked barefoot at a self-selected speed on a 10 meter walkway instrumented with three force plates. Data were imported into a 12-body segment multibody dynamics model (AnyBody Technology) to calculate joint forces. Each leg contained 56 muscles whose mechanical effect was modeled by 159 simple muscle slips, each consisting of a contractile element. The models were scaled to match each subject's anthropometry and BMI. For the control subjects, only one limb was used in determining the relationship between body mass and peak joint force at the hip, knee, and ankle. For the TKA subjects, the peak joint forces were calculated for both the TKA limb and the contralateral limb. Results. Figure 1 shows the knee joint forces for the TKA subjects’ operated (red triangles) and contralateral knees (diamonds) along with the values for the control subjects (circles). Knee joint forces for the TKA subjects fell within or near the upper and lower 95% confidence intervals (dashed lines) of the mean regression lines (solid lines) for the control subjects. Three patients had other lower limb complications (osteoarthritis, ankle surgery). One subject favored the operated limb and another the non-operated limb, as ascertained from the corresponding hip (Figure 2) and ankle joint forces (Figure 3). Discussion. Modeling and simulation can be used to indirectly estimate joint forces in the implanted and non-operated joints. Our gait-lab derived inverse dynamics simulations suggest that joint forces following TKA fall within or near the normal range over a wide range of body weights and that the linear dependence between joint force and body weight applies to the implanted as well as non-implanted joints

Introduction: Osteochondral lesions (OCL) of the talar dome are defects of the cartilaginous surface and underlying bone of the superior articular surface of the talus. Their natural history is uncertain, but the association with residual, debilitating ankle pain is strong. Literature describes OCL’s as occurring anterolaterally or posteromedially, with associated localising symptoms. Early diagnosis of OCL’s may be important in preventing progression. The aim of this study was to investigate the value of clinical findings when compared to MRI scanning. Materials and Methods: Patients with reported OCL’s of the talar dome on MRI were asked to indicate the location of their ankle pain. Subsequently they were physically examined to identify the area of maximum tenderness. Direct visual measures were taken of these sites, using modified anthropometry. The patient, examiner and person measuring were blind to the MRI scan. The lesion on MRI was then measured and locations compared for any correlation, distance and association. Results: A series of eighteen OCL’s were studied. The strongest correlation was between the subject and the examiner in the axial plane (medial/lateral). The weakest was between MRI and clinical locations in the axial plane. Overall, the greatest difference between locations was between clinical examination and MRI. Euclidean distances showed that clinical predictions of lesion site were only reliable to within approximately 5cm. Discussion and conclusion: Although there was a correlation between some locations, measure reliability negated this as the distances between sites represented the maximal distances within the ankle joint. We suggest that OCL of the talar dome result in pain that is poorly localised with respect to the site of the lesion. Suspicion of OCL must remain high in cases of un-resolving ankle pain, irrespective of specific clinical findings and early evaluation with the use of MRI scanning is justified

Introduction: Slipped Capital Femoral Epiphysis (SCFE) is the most common hip problem of adolescence. Obesity and African and Pacific Islander races have been associated with increased susceptibility. In the setting of increasing rates of obesity in Australian adolescents over the last twenty years, it is unknown whether the incidence of this condition is increasing. There are no studies to date on the Australian population and it is unknown whether there is an increased incidence in the local Aboriginal population. Aims: The demographics of SCFE patients presenting to the Women’s and Children’s Hospital (W& CH) in Adelaide were studied, from 1988 to the present, with particular emphasis on weight and race. This was then compared to weight for age percentiles data in the Australian population. The issues of prophylactic pinning of the contralateral side and the efficacy of the department protocol of “pinning in situ” were also studied. Method: Systematic chart review, statistical analysis, and comparison with data from the Australian Bureau of Statistics and the Centre for Applied Anthropometry, University of South Australia, pertaining to weight and racial mix in South Australia. Results: SCFE was associated with obesity. Over 45% of the cohort was above the 95th percentile for weight. The mean weight was in the 85th percentile and the median weight was in the 94th percentile. As an example, the average weight of children aged 12 to 14 years was 13kgs more than the median value of children in this age group. There was a clear increase in incidence of this condition over the last twenty years which corresponds with increasing obesity rates in the community. There was a higher incidence in the indigenous population as compared with the non-indigenous population. Out of the 236 patients enrolled, 5 cases were complicated by avascular necrosis. The overall complication rate was low. Rate of progression to contralateral slip was low as was the rate of prophylactic pinning. Conclusions: Our complication rate when compared to other centres is relatively low and would seem to support our consistent protocol of “pinning in situ”. The low rate of progression to contralateral slip also supports our protocol of watchful surveillance rather than mandatory prophylactic pinning of the contralateral side. We have shown that SCFE is associated with obesity in Australia when compared with general population data. Obesity is also more common in the Aboriginal population and we postulate that this explains the higher incidence of SCFE in this group. In keeping with increasing rates of obesity amongst Australian adolescents, the increasing incidence of this condition further highlights the importance of public health initiatives to tackle obesity in the community

Previous in vivo studies have not documented if ethnicity or gender influence knee kinematics for the healthy knee joint. Other measurements, such as hip-knee-ankle alignment have been previously shown to be significantly different between females and males, as well as Japanese and Caucasian populations in the young healthy knee [. 1. ]. Differences in knee kinematics in high flexion positions may relate to both etiology of osteoarthritis and success in knee replacement designs. Although differences in knee anatomy have been identified, their significance in knee function has not yet been clarified. Therefore, the objective of this study was to determine the 3D, in vivo normal knee kinematics for various subjects from different gender and ethnic backgrounds, and to identify significant differences, if any, between populations. The 3D, in vivo, weight bearing normal knee kinematics was determined for 79 healthy subjects, including 48 Caucasians, 24 Japanese, 42 males, and 37 females. Each participant performed deep knee bend activity from a standing (full extension) to squatting to a lunge motion, until maximum knee flexion was reached. The study was approved by the Institutional Review Board and informed consent form was obtained from all subjects. The 3D bone models, created by segmentation from MR images, were used to recreate the 3D knee kinematics using the previously described fluoroscopic and 3D-to-2D registration techniques (Fig. 1) [. 2. ,. 3. ]. Tibiofemoral rotations were described using the ISB recommended Grood and Suntay convention [. 4. ,. 5. ]. Anterior-posterior translations of the centers of the posterior femoral condyles were normalized due to significantly different anthropometry in the subjects. Anterior cruciate ligament (ACL) laxity was also measured using a KT-1000 device for 72 of these subjects. Statistical analysis was performed using the Student’s t-test, set at the 95% confidence interval. Most subjects achieved very high flexion, however substantial variability occurred in all groups. Range of motion (ROM) varied from 117° to 177°, while average external rotation was 31°± 9.9° for all subjects. Japanese and female subjects achieved greater ROM than Caucasian (p=0.048) and male (p=0.014) subjects. From full extension to 140° of flexion (which 87% of subjects achieved), few significant differences between any of the populations were observed. At deeper flexion, the external rotation was higher for female than for male subjects, however not statistically significant (p=0.0564 at 155°). Also at deep flexion, the adduction was significantly higher for female subjects. The translations of the lateral condyle were very similar between respective groups, but at deep flexion, the medial condyle remained significantly more anterior for females, leading to greater axial rotation and ROM. As ACL laxity increased, flexion/extension ROM significantly increased (r2=0.184, p< 0.001). In addition, ACL laxity was also higher for females (6.8 mm) compared to males (5.6 mm, p=0.011), as well as Japanese (7.5 mm) compared to Caucasian (5.6 mm, p=0.0002) subjects. High variability and ROM in knee kinematics were similar to those seen in previous studies of healthy subjects during a deep knee bending activity [. 6. ]. Subjects in this study achieved much greater axial rotation and ROM than previously analyzed TKA patients. A relationship was found between greater axial rotation and increased ROM, and may be related in part to increased ACL laxity in the knee. Significant differences in ROM and laxity were identified between genders and ethnic groups. Also the medial condyle remaining significantly more anterior for females than for males in deep flexion may explain higher external rotation and consequently higher flexion experienced by women. However, understanding the causes for variability within each group may be the key to improved implant design