Femoral Radius Research Articles

Achieving Specified Laxity in a Noncruciate Total Knee: A Laboratory Design Study

BackgroundNoncruciate total knee arthroplasty designs, including ultracongruent, medially congruent, and medial pivot, are gaining increasing attention in total knee arthroplasty surgery. However, there is no consensus for the bearing surface design, whether there should be different medial, lateral, anterior, and posterior laxities, or whether the medial side should be a medial pivot. This study proposes the criterion of reproducing the laxity of the anatomic knee, defined as the displacements and rotations of the femur on the tibia in the loaded knee when shear and torque are applied. The purpose of this study was to determine the ideal tibial radii to achieve that goal. MethodsThe femoral component was based on the average knee from 100 mild arthritic knee scans. There were 8 tibial components that were designed with different sagittal radii: antero-medial, antero-lateral, postero-medial, and postero-lateral. Radii were defined as the percent height reduction from full conformity with the femoral profile. Components were 3-dimensional–printed. A test rig was constructed where the tibial component was fixed and shear and torque were applied to the femoral component. Displacements and rotations of the femoral component were measured at 0 and 45° of flexion, the latter representing any flexion angle due to the constant femoral sagittal radius. ResultsDisplacements ranged from 0 to 11 mm, and rotations ranged from 1 to 11°. Anterior femoral displacements were higher than posterior due to the shallow distal-anterior femoral profile. The final femoral and tibial components with the most closely matched anatomic laxity values were designed and tested. ConclusionsA steeper distal-anterior femoral radius was an advantage. High medial-anterior tibial conformity was important. However, on the lateral side, the posterior sagittal tibial radius had to be shallower than ideal to allow femoral rollback in high flexion. This meant that the posterior laxity displacements on the lateral side were higher than anatomic, and there was no guidance for lateral femoral rollback.

Increased lateral and medial femoral posterior radius ratios are risk factors for anterior cruciate ligament injury

BackgroundMany studies have shown that distal femoral sagittal morphological characteristics have a clear relationship with knee joint kinematics. The aim of this study was to determine the relationship between distal femoral sagittal morphological characteristics and noncontact anterior cruciate ligament (ACL) injury.MethodsA retrospective case-control study of 148 patients was conducted. Two age- and sex-matched cohorts (each n = 74) were analysed: a noncontact ACL injury group and a control group. Several characteristics were compared between the two groups, including the lateral femoral posterior radius (LFPR), medial femoral posterior radius (MFPR), lateral height of the distal femur (LH), medial height of the distal femur (MH), lateral femoral anteroposterior diameter (LFAP), medial femoral anteroposterior diameter (MFAP), lateral femoral posterior radius ratio (LFPRR), and medial femoral posterior radius ratio (MFPRR). Receiver operating characteristic (ROC) analysis was used to evaluate the significance of the LFPRR and MFPRR in predicting ACL injury.ResultsCompared with patients in the control group, patients in the ACL injury group had an increased LFPR, MFPR, MFAP, LFPRR, and MFPRR. ROC analysis revealed that an increased LFPRR above 31.7% was associated with noncontact ACL injury, with a sensitivity of 78.4% and a specificity of 58.1%; additionally. an increased MFPRR above 33.4% was associated with noncontact ACL injury, with a sensitivity of 58.1% and a specificity of 70.3%.ConclusionThis study showed that increased LFPRR and increased MFPRR are risk factors for developing noncontact ACL injury. These data could thus help identify individuals susceptible to ACL injuries.

Surgical Window and Treatment Strategy for Patient with Multiple Fractures Escaping Inflammatory Response: A Case Report

Today’s Orthopedic surgeons must be adept at the evaluation and management of complicated Multiple Injured Patients (MIP). Despite dynamic strategies, advance modern medical care, the mortality rate of 50-70% has been reported due to high-velocity accidental cases with femoral shaft fractures associated with pelvic fractures and injuries to other organs. We hereby present an interesting case of MIP with the unstable pelvic acetabulum, ipsilateral femoral shaft fracture, floating elbow, and distal radius fracture. It is essential to follow an optimal protocol for such complex fractures. Therefore, we stated the appropriate surgical window and treatment intervention to fix all the major fractures by overcoming the hyperinflammatory state.

Gradual-radius femoral component with s-curve post-cam provides stable kinematics at mid-flexion after total knee arthroplasty

BackgroundMid-flexion instability is the one of the reasons for patient dissatisfaction after total knee arthroplasty (TKA). The purposes of this study were to evaluate in vivo knee kinematics and clinical outcomes using a novel TKA design with a gradual femoral radius component and s-curve post-cam, which are intended to prevent the instability initiated by sudden reductions in the femoral radius observed with conventional components. MethodsWe used radiographic-based, image-matching techniques to analyze femorotibial anteroposterior translation, axial rotation, and anterior/posterior cam-post contact during two dynamic movements, squatting and stair climbing, in 20 knees that had undergone posterior-stabilized fixed-bearing TKA with an improved sagittal profiles of the femoral component and post-cam mechanism. We also evaluated patient-reported outcomes assessed by the 2011 Knee Society Score (KSS 2011). ResultsSquatting and stair climbing produced a similar trend in anteroposterior translation and a relatively small standard deviation at mid-flexion. Although the rotation angles varied widely during squatting and stair climbing, the femoral component was consistently externally rotated. Anterior/posterior cam-post contact during squatting and stair climbing were observed in 0/17 knees and 0/0 knees, respectively. The “Symptoms”, “Satisfaction”, and “Functional activities” subscales of the KSS 2011 were significantly (P < 0.05) improved postoperatively compared to preoperatively (“Symptoms”, 10 to 21; “Satisfaction”, 15 to 26; “Functional activities”, 25 to 71). ConclusionA gradual femoral radius component with an s-curve post-cam provided stable kinematics and favorable clinical results during squatting and stair climbing at 1 year after surgery.

The effect of total knee geometries on kinematics: An experimental study using a crouching machine.

Obtaining anatomic knee kinematics after a total knee is likely to improve outcomes. We used a crouching machine to compare the kinematics of standard condylar designs with guided motion designs. The standard condylars included femoral sagittal radii with constant radius, J-curve and G-curve; the tibial surfaces were of low and high constraint. The guided motion designs were a medial pivot and a design with asymmetric condylar shapes and guiding surfaces. The machine had a flexion range from 0° to 125°, applied quadriceps and hamstring loading, and simulated the collateral soft tissues. The kinematics of all standard condylar knees were similar, showing only small anterior-posterior displacements and internal-external rotations. The two asymmetric designs showed posterior displacements during flexion, but less axial rotations than anatomic knees. The quadriceps forces throughout flexion were very similar between all designs, reflecting similar lever arms. It was concluded that standard condylar designs, even with variations in sagittal radii, are unlikely to reproduce anatomic kinematics. On the other hand, designs with asymmetric constraint between medial and lateral sides, and other guiding features, are likely to be the way forward. The mechanical testing method could be further improved by superimposing shear forces and torques during the flexion-extension motion, to include more stressful in vivo functional conditions.

Variability of human femoral geometry and its implications on nail design

ObjectivesThe objectives of this study are to present a new method of quantifying variability in human femoral geometry and to use this data to optimize intramedullary nail geometry for a better fit within the femoral canal. MethodsComputed tomography (CT) scans of forty intact adult human femora were divided according to race, sex, and age, and were reconstructed digitally into three-dimensional solid models. Geometric features were then measured and compared among groups using ANOVA. An average geometric model was generated, from which an optimal intramedullary (IM) nail curvature function was derived. Insertion of the derived optimal nail and of two currently-available commercial nails into the femur having the highest degree of curvature was then simulated via finite element methods. ResultsSubstantial variability in femoral curvature was observed among the population sample. Sex was found to correlate most strongly with femoral size; males tend to have larger femora than females. Although the average femoral radius of curvature for African Americans was slightly higher than for Caucasians, the difference was not statistically significant. Curvature did not vary across the sample by age, sex or race. Finite element analysis results simulating IM nail insertion using the geometrically-optimized nail showed a substantial decrease in von Mises stress when compared to tested commercially-available IM nails. Fracture was predicted within the posterior canal wall for commercially available nails, as the generated stresses exceeded the allowable stress of cortical bone, but not for the geometrically-optimized nail. ConclusionsConsidering variation in femoral geometry among patients when designing implantable fixation devices may be important. Femoral size differs between adults by sex, with males being larger than females. Pattern of curvature, however, did not differ, although there may be slight differences between European and African Americans. As such, the proposed average femoral curvature function calculated here may be sufficient for the entire population. According to finite element analysis, insertion-induced stresses in the femur were within the allowable range for the geometrically-optimized nail and appear more desirable than in other common nail designs.

Association Between Femoral “Spike” Size After Intramedullary Nailing and Subsequent Knee Motion Surgery

To determine the association between displaced femoral shaft bone fragments ("spikes") seen on radiographs after intramedullary nail insertion and the need for future motion surgery. Retrospective case-control study. Academic trauma center. We included patients with femoral shaft fractures treated with intramedullary nail insertion. Case patients (n = 22) had developed knee stiffness treated with motion surgery. The control group was a randomly selected sample (1:3 ratio). Motion surgery to address knee stiffness. We defined a "spike distance ratio" and "spike area ratio" from initial postoperative anteroposterior and lateral radiographs. Multivariable logistic regression determined the effect of spike distance and area ratios on the likelihood of need for motion surgery, controlling for polytraumatic injuries and bilateral fractures. The case group had a median femoral spike distance ratio of 1.9 [interquartile range (IQR), 1.6-2.5] compared with 1.5 (IQR, 1.2-1.8) in the control group. An increased femoral spike distance ratio was associated with increased odds of motion surgery (P < 0.01). A femoral spike distance >2 times the femoral radius had 32 times the odds (95% confidence interval, 2-752) of motion surgery compared with patients with distance ratios <1.25. Median femoral spike area ratios were similar between the case (0.2; IQR, 0.1-0.5) and control (0.2; IQR, 0.0-0.5) groups and were not associated with increased odds of motion surgery (P = 0.34). A larger spike distance ratio is associated with increased odds of subsequent motion surgery. Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Videofluoroscopic Evaluation of the Influence of a Gradually Reducing Femoral Radius on Joint Kinematics During Daily Activities in Total Knee Arthroplasty

BackgroundParadoxical anterior translation in midflexion is reduced in total knee arthroplasties (TKAs) with a gradually reducing femoral radius, when compared to a 2-radii design. This reduction has been shown in finite element model simulations, in vitro tests, intraoperatively, and recently also in vivo during a lunge and unloaded flexion-extension. However, TKA kinematics are task dependent and this reduction has not been tested for gait activities. MethodsThirty good outcome subjects (≥1 year postoperatively) with a unilateral cruciate-retaining TKA with a gradually reducing (n = 15) or dual (n = 15) femoral radius design were assessed during 5 complete cycles of level walking, stair descent (0.18-m steps), deep knee bend, and sitting down onto and standing up from a chair, using a moving fluoroscope (25 Hz, 1 ms shutter time). Kinematic data were extracted by 2D/3D image registration. ResultsTibiofemoral ranges of motion for flexion-extension, abduction-adduction, internal-external rotation, and anteroposterior (AP) translation were similar for both groups, whereas the pattern of AP translation-flexion-coupling differed. The subjects with the dual-radii design showed a sudden change in direction of AP translation around 30° of flexion, which was not present in the subjects with the gradually reducing femoral radius design. ConclusionThrough the unique ability of moving fluoroscopy, the present study confirmed that the gradually reducing femoral radii eliminated the paradoxical sudden anterior translation at 30° present in the dual-radii design in vivo during daily activities, including gait and stair descent.

Comparative studies of bone density by quantitative ultrasound (QUS) with dual-energy X-ray absorptiometry (DEXA) scan

Background: The aim of the study was to establish the correlation quantitative ultrasound (QUS) between and dual-energy X-ray absorp­tiometry (DEXA) and to assess the ability of QUS as a screening tool for osteoporosis.&#x0D; Methods: The study was conducted on 115 patients. All the patients underwent QUS of radius using Sunlight MiniOmni bone sonometer and DEXA screening for measurement of bone mineral density (BMD) at lumbar spine, total left &amp; femoral neck and radius.&#x0D; Results: Significant correlations were observed between QUS and DEXA T score.&#x0D; Conclusions: QUS is a sensitive screening tool to detect changes in the bone mass and risk of osteoporosis.

RISK FACTORS OF LOW-ENERGY FRACTURES IN PATIENTS WITH TYPE 2 DIABETES MELLITUS

Osteoporosis is a metabolic disease of the bone tissue, which is characterized by a violation of the qualitative (microarchitecture change) and quantitative characteristics (decreased bone mass) of the skeleton, and, as a result, lowenergy fractures. The medical and social significance of osteoporosis is due to its consequences: fractures of the femoral neck, vertebral bodies, radius and other large bones of the skeleton, which significantly reduces the quality of patients’ lives and entails significant financial costs for treatment and rehabilitation. Prevalence of diabetes mellitus (DM) significantly increases in all countries of the world, including the Russian Federation. Diabetes and osteoporosis were considered to be individual diseases for a long time. In many prospective large-scale studies it was proved that patients with T2DM have a greater risk of falls and fractures in contrast with the overall population. Despite the increased risk of fractures in diabetic patients, there is still no risk stratification in these patients. The link between the classic risk factors of osteoporotic fractures (such as chronic intake of glucocorticoids, use of alcohol, tobacco, etc.) and the occurrence of fractures is similar in patients with both T2DM and without it. However, it is necessary to take into account other characteristics of diabetes. The specific risk factors of fractures in T2DM patients are duration of the diabetes for more than 10 years, diabetes decompensation, the severity of diabetes, obesity, the frequency of falls, hypoglycemia, insulin, thiazolidinedione, exenatide, sulfonylureas, canagliflozin therapy, and, most likely, the reduction of 25 (OH) vitamin D, functional hypoparathyroidism, the increase of sclerostin, pentosidine, decreased bone mineral density (BMD) of the hip.

PMD18 - A Cost-Effectiveness Analysis of u sing an Innovative Gradually Reducing Femoral Radius Design Implant VS. A Class of Metal-Backed Implants for Patients Undergoing Total Knee Arthroplasty (TKA) Surgery from an Indian Societal Perspective

To investigate the cost-effectiveness of using an innovative gradually reducing femoral radius design implant (GRAD) vs. a class of metal-backed implants (SOC) for patients with osteoarthritis who require a total knee arthroplasty (TKA) in both the public and private sectors in India. A Markov model was developed to compare the costs and outcomes of using GRAD vs. SOC over a 10-year time horizon in both the public and private sectors in India. The health states included were full benefit after primary TKA, limited benefit after primary TKA, primary TKA failure, full benefit after revision TKA, limited benefit after revision TKA and failure of revision TKA. The model assessed both direct and indirect costs such as cost of implant, surgery, hospitalisation, follow-up visits and productivity loss. One-way sensitivity analysis and probabilistic sensitivity analysis tested the robustness of the base case incremental cost-effectiveness ratio. Provisional results show that after 10 years the expected difference in the total cost of using GRAD vs a SOC per patient is (-₹4,170 or -₹7,224) in the public and private sectors respectively. The increment in quality-adjusted life years (QALYs) per patient is (0.0072 or 0.0068) for the public and private sectors respectively. Therefore using the innovative design implant is the economically dominant strategy as it produces more QALYs at a lower cost than SOC. The model results were most sensitive to the cost of the surgery, the probability of knee survivorship, and the discount rates. Provisional results indicate that using the innovative gradually reducing femoral radius design implant in Indian patients undergoing a TKA is cost-effective in both the public and private sectors compared to class of metal-backed implants and is therefore likely to result in better allocation of resources for the Indian healthcare system.

Modifications of femoral component design in multi-radius total knee arthroplasty lead to higher lateral posterior femoro-tibial translation.

As the aims of changes in total knee arthroplasty (TKA) designs are to reinstate more natural kinematics, the current study evaluated the in vivo kinematics in patients who underwent a cruciate retaining gradually changing femoral radius ("G-CURVE") against a cruciate retaining conventional changing femoral radius ("J-CURVE") geometry TKA design. The hypothesis of the study is that the G-CURVE design would allow a substantial increase in the femoral rollback compared to the J-CURVE design. Retrospective study design. Thirty patients were included (G-CURVE, n=20; J-CURVE, n=10). Single-plane fluoroscopic analysis and marker-based motion capture gait analysis was performed to analyse dynamic tibiofemoral motion during weight-bearing and unloaded activities at 24month after index surgery. The analysis of the medial and lateral points on the tibia plateau during the unloaded flexion-extension and the weight-bearing lunge activities revealed a significant difference in femoral rollback in G-CURVE TKA above 60° (p=0.001) and 30° (p=0.02) of knee flexion, respectively. Moreover, the lateral condyle of the G-CURVE showed a higher extent of femoral rollback while the lateral condyle of the J-CURVE rolled forward. At 2years post-operative, the G-CURVE TKA showed significant differences in femoro-tibial translation in comparison with the J-CURVE system, in vivo. The G-CURVE resulted in an increased lateral rollback and simultaneously in an elimination of the paradoxical medial roll-forward present in the J-CURVE design. Moreover, knee kinematics analysis showed significant differences between unloaded and weight-bearing conditions revealing the impact of load and muscle force. The analysis conducted in this study contributes to further understand the principal movement characteristics in widely used older designs in comparison with recently developed concepts to get a better overview on their potential benefits on in vivo kinematics. III.

Case series report of navigation-based invivo knee kinematics in total knee arthroplasty with a gradually reducing femoral radius design.

BackgroundSimulations show that paradoxical anterior femoral slide in conventional dual radius total knee arthroplasty (TKA) is initiated by sudden reduction of the femoral radius from distal to posterior. Therefore, we hypothesized that a new TKA prosthesis design with a gradually reducing femoral radius may minimize the anterior slide in navigation-based in vivo knee kinematics. The purpose of this study was to compare the kinematics of TKA in vivo using a prosthesis with a gradually reducing radius, in comparison with the conventional dual radius design.MethodsA retrospective case series report was performed for 12 knees with osteoarthritis using a CT-free navigation system. Six knees received TKA using a prosthesis with a gradually reducing femoral radius (Attune CR) and the other 6 knees underwent TKA using a conventional dual radius design (PFCΣ CR). Anterior-posterior (AP) displacement of the medial and lateral femoral condyles relative to the tibia, and kinematic patterns of the femur throughout the range of motion were compared between the groups.ResultsThe average AP displacement in the Attune CR group indicated no paradoxical anterior movement of both condyles, and kinematic data showed a medial pivot pattern. In contrast, AP displacement in the PFCΣ CR group indicated that both condyles showed paradoxical anterior movement, and kinematically both condyles moved in the same manner, showing a parallel motion pattern.ConclusionTKA using a prosthesis with a gradually reducing radius minimized paradoxical anterior slide in navigation-based in vivo knee kinematics.

Peer review report 1 on “Case series report of navigation-based in vivo knee kinematics in total knee arthroplasty with a gradually reducing femoral radius design”

Peer review report 1 on “Case series report of navigation-based in vivo knee kinematics in total knee arthroplasty with a gradually reducing femoral radius design”

Normal radiological unossified hip joint space and femoral head size development during growth in 675 children and adolescents

Evaluation of hip joint space width during child growth is important to aid in the early diagnosis of hip pathology in children. We established reference values for hip joint space and femoral head size for each age. Hip joint space development during growth was retrospectively investigated medial and cranial in 1350 hip joints of children using standard anteroposterior supine plain pelvic radiographs. Maximum capital femoral epiphysis diameter and femoral radii were further more investigated. Hip joint space values show a slow decline during growth. Joint space was statistically significantly (p < 0.006) larger in boys than girls. Our hip joint space measurements on supine subjects seem slightly larger than those reported by Hughes on standing subjects. Evaluation of the femoral head diameter and the radii showed a size curve quite parallel to the known body growth charts. Radii medial and perpendicular to the physis are not statistically significantly different. We recommend to compare measurements of hip joint space at two locations to age dependent charts using the same imaging technique. During growth, a divergence in femoral head size from the expected values or loss of the spherical shape should raise the question of hip disorder. Clin. Anat. 30:267-275, 2017. © 2016 Wiley Periodicals, Inc.

Evaluation of serum undercarboxylated osteocalcin in premenopausal rheumatoid arthritis patients: its correlation with disease activity and bone mineral density

There is a definite role of vitamin K and undercarboxylated osteocalcin (ucOC) on bone mineral density (BMD) in rheumatoid arthritis (RA). Up to our knowledge, no other work has discussed the relationship between ucOC and BMD in premenopausal RA patients and its correlation with disease activity. Sixty premenopausal RA female patients and 30 healthy premenopausal controls of matched age were included. All were subjected to clinical examination, laboratory investigations including serum level of ucOC, disease activity measurement using DAS-28 score, and BMD measurement using dual-energy X-ray absorptiometry. The level of ucOC was significantly higher in patients with RA than in controls (P<0.001). BMD in patients was found to be significantly lower compared with controls in the spine, femoral neck, and distal radius areas. The most frequent osteoporotic site according to Z-score was the spine (16.7%), followed by the femoral neck (8.3%) and distal radius (6.7%). The most common commonest osteopenic site according to Z-score was the spine (31.7%), followed by the femoral neck (21.7%) and the distal radius (16.7%). Our work showed that ucOC level was found to be high in premenopausal RA patients with higher DAS values than in those with lower DAS value (P<0.001). In our work, BMD measured by means of dual-energy X-ray absorptiometry scan was found to be lower with higher DAS values and vice versa. Serum level of ucOC (which is a mirror of vitamin K deficiency) was found to be higher in premenopausal RA patients than controls and correlated positively with disease activity and inversely with BMD measurement.

Longitudinal Follow-up Study of Bone Mineral Density in Adult Survivors of Solid Pediatric Cancers

To investigate the hypothesis that abnormal bone mineral density in pediatric solid tumor survivors persists into early adulthood, a follow-up study to our original cross-sectional study was undertaken in two parts. In Part I, the original cohort of 38 patients was updated to include 3 additional patients. The results showed a 34% prevalence of osteopenia and a 12% prevalence of osteoporosis in at least one site. 1 The part II study cohort consisted of 14 of the original 38 patients who returned more than 5 years later for repeat dual energy x-ray absorptiometer (DEXA). Overall, during the 5-year interval, 100% of the part II patients showed a decrease in bone mineral density (BMD) at one or more sites and 28.5% showed decreased total body BMD. Statistically significant (p<0.05) overall declines in BMD were seen in the right femoral neck and left distal radius. Young survivors of childhood tumors do not exhibit normal bone mineral density progression and warrant consideration of early preventative intervention.

Predicting the optimal entry point for femoral antegrade nailing using a new measurement approach.

To establish a new reliable approach for measuring proximal femoral anatomical parameters and determining the optimal entry point of the antegrade intramedullary (IM) nailing. A new method for measuring the proximal femoral anatomy and locating the optimal entry point for the antegrade nailing was developed using Mimics and 3-Matic softwares (Materialise, Haasrode, Belgium). After verifying the reliability of the measurement method using 15 pairs of the femoral models by the intraclass correlation coefficient, the anatomical parameters of 200 Chinese femurs were measured, and statistical analyses were performed to compare the proximal femoral anatomical parameters between different genders or lateralities and determine the most relevant factors of the optimal entry point. Reliability study showed that both intraobserver reliability and interobserver reliability of the current measurement approach were excellent. After independent samples [Formula: see text]-test, the proximal femoral anatomical parameters were shown significant difference between genders. Stepwise regression statistical analyses showed that the most relevant factors of the distances between the optimal entry point and the femoral head centre, the femoral neck axis and the tip of the greater trochanter were the 3D femoral neck-shaft angle (Pearson's [Formula: see text]; the model's [Formula: see text]), the femoral radius (Pearson's [Formula: see text]; the model's [Formula: see text]) and the femoral length (Pearson's r = 0.316; the model's [Formula: see text]), respectively. The current study provided a new and reliable measurement approach to evaluating the anatomical morphology of the proximal femur and revealed the most influential factors on the locations of the simulated optimal entry point for the proximal femoral antegrade IM nailing. Furthermore, this study was useful for establishing methodological basis for future researches and developments of the custom-made IM nailing and affiliated surgical instruments.

Variation in the Femoral Bow

To evaluate femoral radius of curvature in a large sample of computed tomography scans to definitively determine the relationship between radius of curvature and femoral length, age, gender, ethnicity, body mass index and cortical thickness. A retrospective review was conducted of the electronic medical records and advanced imaging of 1961 patients who underwent pulmonary embolism protocol computed tomography scans between December 1999 and March 2010. The computed tomography scans were imported from the clinical picture archiving and communication system archive into a research image archive and analysis system. Each scan was processed by an automated system that algorithmically determined bony landmarks, adjusted for body position within the scanner and measured the radius of curvature. The mean medullary radius of curvature of 3922 femurs was 112 cm (SD = 26 cm). The mean anterior radius of curvature of the femurs was 145 cm (SD = 55 cm). There was a moderately strong positive correlation (0.36-0.39) between femoral length and radius of curvature (P < 0.0001) that was not affected by age, body mass index, cortical thickness, gender, or ethnicity. No significant relationship was found between either gender or ethnicity and radius of curvature independent of femoral length. Differences in radius of curvature based on ethnicity and gender exist primarily because of the variation in average height, and therefore femur length, that exists between ethnic groups and genders. These data may prove useful in the design of safer intramedullary implants that accommodate a greater spectrum of anatomic variation.

Outcome and Range of Motion Using a High-flexion Cruciate-retaining TKA

Increased knee flexion after total knee arthroplasty (TKA) may contribute to patients' increased satisfaction and more active lifestyles. This study evaluated a TKA component designed for high flexion (more than 125°). The design features an anatomic sagittal femoral radius with short, flared femoral condyles to allow for femoral rollback. Fifty TKA procedures in 47 patients were evaluated prospectively regarding clinical outcomes using Knee Society knee and function scores, Short Form 12 physical component scores, and flexion measured clinically and by digital lateral supine active flexion radiographs. Preoperative and 1-year postoperative radiographs were analyzed by an independent observer. Mean maximum flexion measured clinically was 115° preoperatively and 120° one year postoperatively, with 76% of TKAs achieving more than 120° and 44% achieving more than 125°. Sex, body mass index, and preoperative flexion were not predictors of postoperative flexion. Mean flexion by radiograph was 108° preoperatively and 111° one year postoperatively, with 31% of knees achieving more than 120° and 14% more than 125°. Mean Knee Society knee and function scores and the Short Form 12 physical component scores were 52, 55, and 32 preoperatively, respectively, and 89, 77, and 40 one year postoperatively, respectively. Of the 50 knees, 84% had improvement in their Knee Society function scores, and 76% had improvement in their Short Form 12 physical component scores. The study revealed evidence of increased early postoperative flexion with the use of a cruciate-retaining high-flexion TKA design.