Dual plating of the medial and lateral distal femur has been proposed to reduce angular malunion and hardware failure secondary to delayed union or nonunion. This strategy improves the strength and alignment of the construct, but it may compromise the vascularity of the distal femur paradoxically impairing healing. This study investigates the effect of dual plating versus single plating on the perfusion of the distal femur. Ten matched pairs of fresh-frozen cadaveric lower extremities were assigned to either isolated lateral plating or dual plating of a single limb. The contralateral lower extremity was used as a matched control. A distal femoral locking plate was applied to the lateral side of ten legs using a standard sub-vastus approach. Five femurs had an additional 3.5mm reconstruction plate applied to the medial aspect of the distal femur using a medial sub-vastus approach. The superficial femoral artery and the profunda femoris were cannulated at the level of the femoral head. Gadolinium MRI contrast solution (3:1 gadolinium to saline ration) was injected through the arterial cannula. High resolution fat-suppressed 3D gradient echo sequences were completed both with and without gadolinium contrast. Intra-osseous contributions were quantified within a standardized region of interest (ROI) using customized IDL 6.4 software (Exelis, Boulder, CO). Perfusion of the distal femur was assessed in six different zones. The signal intensity on MRI was then quantified in the distal femur and comparison was made between the experimental plated limb and the contralateral, control limb. Following completion of the MRI protocol, the specimens were injected with latex medium and the extra-osseous vasculature was dissected. Quantitative MRI revealed that application of the lateral distal femoral locking plate reduced the perfusion of the distal femur by 21.7%. Within the dual plating group there was a reduction in perfusion by 24%. There was no significant difference in the perfusion between the isolated lateral plate and the dual plating groups. There were no regional differences in perfusion between the epiphyseal, metaphyseal or meta-diaphyseal regions. Specimen dissection in both plating groups revealed complete destruction of any periosteal vessels that ran underneath either the medial or lateral plates. Multiple small vessels enter the posterior condyles off both superior medial and lateral geniculate arteries and were preserved in all specimens. Furthermore, there was retrograde flow to the distal most aspect of the condyles medially and laterally via the inferior geniculate arteries. The medial vascular pedicle was proximal to the medial plate in all the dual plated specimens and was not disrupted by the medial sub-vastus approach in any specimens. Fixation of the distal femur via a lateral sub-vastus approach and application of a lateral locking plate results in a 21% reduction in perfusion to the distal femur. The addition of a medial 3.5mm reconstruction plate does not significantly compromise the vascularity of the distal femur. The majority of the vascular insult secondary to open reduction, internal fixation of the distal femur occurs with application of the lateral locking plate

Introduction. The use of vascularised fibula grafts is an accepted method for reconstructing the distal femur following resection of malignant childhood tumours. Limitations relate to the mismatch of the cross-sectional area of the transplanted fibula graft and thel ocal bone, instability of the construct and union difficulties. We present midterm results of a unique staged technique—an immediate defect reconstruction using a double-barrel vascularised fibula graft set in in A-frame configuration and a subsequent intramedullary femoral lengthening. Materials & Methods. We retrospectively included 10 patients (mean age 10 y)with an osteosarcoma of the distal femur, who were treated ac-cording to the above-mentioned surgical technique. All patients were evaluated with regards to consolidation of the transplanted grafts, hypertrophy at the graft-host junctions, leg length discrepancies, lengthening indices, complications as well as functional outcome. Results. The mean defect size after tumour resection was 14.5 cm, the mean length of the harvested fibula graft 22 cm, resulting in a mean (acute) shortening of 4.7 cm (in 8 patients). Consolidation was achieved in all cases, 4 patients required supplementary bone grafting. Hypertrophy at the graft-host junctions was observed in78% of the evaluable junctions. In total 11 intramedullary lengthening procedures in 9 patients had been performed at the last follow up. The mean Muskuloskeletal Society Rating Scale(MSTS) score of the evaluable 9 patients was 85% (57% to 100%)with good or excellent results in 7 patients. Conclusions. A-frame vascularised fibula reconstructions showed encouraging results with respect to defect reconstruction, length as well as function and should therefore be considered a valuable option for reconstruction of the distal femur after osteosarcoma resection. The surgical implementation is demanding though, which is emphasized by the considerable high number of com-plications requiring surgical intervention, even though most were not serious

Introduction. The human body is a complex and continually adapting organism. It is theorised that the morphology of the proximal femur is closely related to that of the distal femur. Patients that have abnormal anatomy in the proximal femur, such as a high femoral neck anteversion angle, may have abnormal anatomy in the distal femur to overcome proximal differences. This phenomenon is of key interest when performing Total Hip Replacement (THR) or Total Knee Replacement (TKR) surgery. The current design and placement of existing hip and knee implants does not account for any correlation between the anatomical parameters of the proximal and distal femur, where bone anatomy may have adapted to compromise for abnormalities. A preliminary study of 21 patients has been carried out to assess the relationship between the proximal and distal femur. The difficulties in defining and measuring key anatomical parameters on the femur have been widely discussed in the literature [1] due to its complex three dimensional geometry. Using CT scans of healthy octogenarians, it was possible to mark key anatomical landmarks which could be used to define various anatomical axes throughout the femur. Correlation analyses could then be carried out on these parameters to assess the relationship between proximal and distal femur morphology. Methods. Each femur was initially realigned along the mechanical axis (MA); defined by joining the centre of the femoral head (FHC) to the centre of the intercondylar notch (INC) [2]. All anatomical landmarks were then identified using the Materialise Mimics v12 software (Figure 1 and 2) and exported into Microsoft Excel for analysis. Key anatomical parameters which were derived from these landmarks included the femoral neck axis (FNA), femoral neck anteversion angle (FNAA) [1–4], condylar twist angle, clinical transepicondylar axis (TEA), trochlea sulcus angle and medial and lateral trochlea twist. A correlation analysis was carried out on SPSS Statistics v20 (IBM) to assess the relationship between proximal and distal anatomical parameters. Results. The correlation analysis displayed a positive linear correlation between the FNAA and the clinical TEA (adjusted R squared = 0.471, p < 0.001) indicating that an abnormally high FNAA is correlated with a higher TEA angle (Figure 3). No strong relationship was found between the FNAA and the additional distal parameters compared, in particular there was no trend between the FNAA and the geometry of the trochlea as measured by the sulcus angle and trochlea twist. Discussion. The morphology of the distal femur seems to be at least partially correlated with the proximal femur and the relationship should be studied further to assess any potential effect on THA and TKA surgery. An extension of this study should assess an increased patient sample size and further anatomical parameters

Background. Most of contemporary total knee systems address on improving of range of motion and bearing materials. Although new total knee designs in most systems accommodated the knee morphology according to gender differences, reestablishing of the same anterior offset of the distal femur during total knee arthroplasty (TKA) has not been well addressed. Furthermore, in most total knee systems, the anterior offset of the femoral component is constant regardless of the increment of the femoral size. We hypothesized that change of the anterior offset of the distal femur during TKA might affect the quadriceps strength and immediate clinical outcomes which may result in improved design of the future femoral component. Purpose. To evaluate the peak quadriceps strength and immediate clinical outcomes related to the change of anterior offset of the distal femur during TKA. Materials & Methods. We prospectively evaluated 75 patients (75 knees) who had primary osteoarthritis and underwent an uncomplicated TKA. A measured-resection technique of surgery using a single design of semi-constrained posterior-stabilized prosthesis with patellar resurfacing was used in all knees. In every TKA, the patellar resection was quantified in order to provide a similar thickness of the patellar composite to the original patellar thickness. A uniform perioperative protocol was applied. The mean thickness from the medial and lateral sides of the resected anterior femur were evaluated and compared with the mean thickness of the anterior part of the femoral component. The peak quadriceps strength and peak hip flexor strength was evaluated before surgery, and then at 2 weeks, 6 weeks and 3 months, postoperatively, using a digital dynamometer. The Difference of thickness between the resected anterior femoral bone and the anterior femoral component was defined as the change of the anterior offset of the distal femur. Clinical outcomes, including Knee Society Scores (KSS) and Western Ontario and McMaster University Arthritis Index (WOMAC) scores at 2 weeks, 6 weeks and 12 weeks were evaluated in relation of muscle strengths. Results. Patients were divided in 2 groups according to the change of the anterior offset of the distal femur during TKA. Thirty knees (group A) had similar or increased anterior offset of the distal femur and 45 knees (group B) had decreased anterior offset of the distal femur. The mean thickness of the resected anterior femoral bones in group A and B were 4.8 mm and 9.7 mm, respectively. The mean changes of anterior offset in group A and B were (+)0.7 mm and (−)4.2 mm with statistical difference (p, 0.01). There were no differences in patient's demographic data including age, sex, and body mass index (BMI). Preoperatively, both groups had similar mean peak quadriceps strength (108.04 N vs.115.52 N, p, 0.191) and mean peak hip flexor strength (105.98 N vs.108.05 N, p.0.745). At 2-week follow-up (FU), group A had significantly better peak quadriceps strength (111.53 N vs. 99.75 N, p, 0.03) and improve of total WOMAC score (32.4 points vs. 27.4 points, p, 0.03) than those of group B, The improved WOMAC score was statistical significant in subgroup of function (16.7 points vs. 12.7, p, 0.04) However, the peak hip flexor strength, KSS clinical scores and function scores were not different. At 6-week FU 12-week FU, there were no differences in all measuring parameters. Discussion and Conclusion. Biomechanical study has shown that the anterior offset of the distal femur provides role as a lever arm for a proper quadriceps function. Therefore, with maintaining of the patellar thickness during TKA in individual patient, a constant thickness of the anterior offset of the femoral component regardless of size may result in change of the anterior offset of the distal femur and may affect the function of quadriceps. The present study demonstrated that, at 2 weeks postoperatively, patients who had increased anterior offset of the distal femur could significantly gain better peak quadriceps strength and improved WOMAC function score than those who did not. In addition, change of anterior offset of the distal femur had no relation with the peak hip flexor strength. A mean 4.2-mm decreasing of anterior offset of the distal femur during TKA caused a shorter lever arm to the quadriceps and resulted in reducing the peak quadriceps strength with no gross effect on hip flexor strength. Although peak quadriceps strength in patients who had increased anterior offset of distal femur correlated with improved WOMAC function score, this marginal statistical significance provided a very short time for advantages. As there was a similar or slightly increased of anterior femoral offset in Group A, the anterior overstuff should be very minimal. At 6 weeks and 12 weeks after surgery, we found that investigated parameters, as well as clinical outcomes, were not different in both groups. We concluded that the change of femoral offset during TKA provided a short effect on quadriceps strength and clinical outcomes for few weeks which had no clinical impact on the drive to improve the prosthetic design of the femoral component which has a constant thickness of the anterior offset

Purpose. The purpose of this study is to analyse regional differences in the microstructural and mechanical properties of the distal femur depending on osteoarthritic changes using micro-images based on finite element analysis. Materials and Methods. Distal femur specimens were obtained from ten donors composed of 10 women with OA (mean age of 65 years, ranging from 53 to 79). As controls, the normal distal femur was sampled from age and gender matched donors consisting of 10 women(mean age of 67 years, ranging from 58 to 81). The areas of interest were six regions of the condyles of the femur(Lateral-Anterior, Middle, Posterior; Medial=Anterior, Middle, Posterior). A total of 20 specimens were scanned using the micro-CT system. Micro-CT images were converted to micro-finite element model using the mesh technique, and micro-finite element analysis was then performed for assessment of the mechanical properties. Results. Trabecular bones from the distal femur in control and OA groups exhibited different microstructural and mechanical properties in the same region. BV/TV, Tb.N, Tb.S and Yield strength were different between LA and MMsignificantly (p=0.005). In control group, the lateral anterior region of the distal femur reflected subchondral trabecular remodeling, while in advanced OA group, the medial middle region showed prominent changes in the microstructural and mechanical properties. Conclusion. The authors concluded that with aging and the progress of primary OA, changes of patello-femoral reaction force induced subchondral trabecular changes of the anterolateral region initially, and then progressed to the medial middle and posterior region in advanced OA

Purpose. Analysis of the morphology of the distal femur, and by extension of the femoral components in total knee arthroplasty (TKA), has been related to the aspect ratio, which represents the width of the femur. Little is known about variations in trapezoidicity (i.e whether the femur is more rectangular or more trapezoidal). This study aimed to quantify additional morphological characteristics of the distal femur and identify anatomical features associated with higher risks of over- or under-sizing of components in TKA. Method. We analyzed the shape of 114 arthritic knees at the time of primary TKA using the pre-operative CT scans. The maximum AP dimension was measured. The mediolateral dimensions were measured on the theoretical distal resection slice at three levels: the posterior region (MLP), the central region (MLC) and the anterior region (MLA) (Fig 1). The ‘aspect’ ratio (MLC/AP) ratio quantified how wide or narrow the shape is. The ‘trapezoidicity’ ratio (MLP/MLA) ratio quantified how rectangular or trapezoidal the shape is. We also quantified the medial and lateral ‘narrowing angles’ in the anterior and central zones (α and β) (Fig 2). The post-operative prosthetic overhang was calculated from CT-scan. We compared the morphological characteristics with those of twelve TKA models scanned using a three-dimensional optical scanning machine (ATOS II, GOM mbH, Braunschweig, Germany) and its photogrammetric analysis software (TRITOP, GOM mbH, Braunschweig, Germany). Results. There were significant variations in both the aspect ratio (1.16±0.07; range 0.98–1.31) and the trapezoidicity ratio (1.21±0.08; range 1.06– 1.46). Femoral trapezoidicity was mostly due to an inward curve of the medial cortex. The multivariate analysis indicated that prosthetic overhang was correlated to the ‘aspect ratio’ (more overhang in narrow femurs, p=0.002), to the ‘trapezoidicity ratio’ (more overhang in trapezoidal femurs, p=0.002), and to the Tibio Femoral Angle (more overhang in valgus knees, p=0.035). The geometries of the twelve specimen components can be compared directly with the morphological findings of this study. Some components had excessively low trapezoidicity ratios (i.e. were too rectangular) such as DePuy LCS and Stryker Scorpio. Other designs had trapezoidicity ratios closer to anatomic values such as Zimmer Nexgen, Zimmer Persona, DePuy Attune and Smith and Nephew Journey (Fig 3). Several components had excessively low anterior lateral narrowing angle (αL) such as DePuy LCS, Stryker Scorpio. All had insufficiently low medial narrowing angles. Conclusion. This study shows that rectangular/trapezoidal variability of the distal femur cannot be ignored. Most of the femoral components, which were tested appeared to be excessively rectangular when compared with the bony contours of the distal femur. These findings suggest that the design of TKA should be more concerned with matching the trapezoidal/rectangular shape of the native femur

Objective. In a cruciate retaining total knee arthroplasty (CR-TKA) for patients with flexion contracture, to ensure that an extension gap is of sufficient size to install an implant, the amount of distal femur bone resection needed is frequently larger in a patient with knee flexion contracture than in one without contracture. In this study, we compared the distal femur bone resection amount, the component-secured extension gap margin value, and the range of motion at 6 months after surgery between patients with knee flexion contracture and those without knee flexion contracture. Method. We examined 51 joints including 27 joints in patients with preoperative extension limitation of less than 5 degrees (the F0 group) and 24 joints in patients with limitation of 15 degrees or larger (up to 33 degrees; the FC group) who underwent CR-TKA with LCS RP (DePuy Synthes) between May 2013 and April 2014. In case with an extension gap 3 mm or smaller than the flexion gap after initial bone resection, we released posterior capsule adequately, trying to minimize the distal femur additional bone resection amount as possible. With installation of a femoral trial, the component gaps were measured using spacer blocks. The measured parameters included the intraoperative bone resection length, gap difference (FG − EG, i.e., difference between the flexion gap [FG] and extension gap [EG]), and range of motion 6 months after surgery. Results. No inter-group difference was found in the length of the distal femur bone initially resected in the medial side of distal femur(F0: 6.7 ± 1.3 mm, FC: 6.1 ± 1.4 mm) and total length of bone resection (= first + additional resection) in the lateral proximal tibia (F0: 10.3 ± 1.9 mm, FC: 10.4 ± 2.1 mm). The length of the additional distal femur bone resected was 0.9 ± 1.3 mm in the F0 and 1.5 ± 1.2 mm in the FC (P = 0.06; Mann-Whitney U). The FG-EG (F0: 0.7 ± 0.9 mm, FC: 0.6 ± 0.8 mm) showed no remarkable inter-group difference. The mean range of motion was changed from −2.3° to −0.6° at extension and from 130.4° to 128.7° at flexion in the F0 and from −19.8° to −2.7° at extension and from 113.7° to 122.3° at flexion in the FC. Conclusions. The amount of distal femur bone resected should not be simply increased because this may elevate the joint line, narrow the flexion range, and cause the joint instability in mid-flexion. The results of this study show that, in CR-TKA for patients with flexion contracture up to 30°, the length of distal femoral bone resection of approximately 1 mm larger than that in patients without contracture may ensure an extension gap of necessary and sufficient length to install an implant

Introduction. Accurate alignment and sizing of the femoral component in total knee arthroplasty (TKA) is important for stability and functional outcomes. In relation to the shape of the distal femur, it has been reported that the medial-lateral (ML) femur width in women is narrower than that in men for the same antero-posterior (AP) length. In addition, it has been noted that the elevation of the anterior condyle in women is lower than that in men. Therefore, in TKA for women, it is suggested that a medial or lateral overhanging femoral component can cause pain or limit the range of motion (ROM). As a result, a gender-specific implant for women has been developed. However, there are few studies addressing the morphological dimensions of the distal shape of the femur in the Japanese population. The objective of this study was to reveal the appropriateness of using gender-specific implant for Japanese women. Methods. This study was based on 40 women (40 knees) and 40 men (40 knees) who had primary preoperative osteoarthritis of the knee. The average height was 161.2 cm for men and 149.4 cm for women. The average weight was 68.0 kg for men and 58.5 kg for women. These are significantly different. Resection of the distal femur for TKA was simulated with preoperative computed tomography (CT) data. The ML width on the anterior and distal cut surface, the ML width at the surgical epicondylar axis (SEA) level, the maximum AP length at the medial and lateral condyle, and the AP length after resection were measured. These values were compared between men and women, and compatibility with NexGen LPS-Flex and Gender Solution Femur (GSF) (Zimmer, Warsow, Ind) was evaluated. Results. On the anterior cut surface, the average ML width was 54.0 mm for men and 47.0 mm for women. There was a significant difference between them (P<0.01). The aspect ratio (AP/ML) at the SEA level and the resected distal surface was 0.74 and 0.65 for men and 0.76 and 0.70 for women, respectively. There were significant differences between them (P<0.01). Discussion and Conclusion. In general, the aspect ratio of the distal femur in the Japanese population was smaller than that in the Caucasian population. However, the femoral distal shape in women was narrower than that in men for the same AP length in the Japanese population. As the AP size increased, the femoral component in women tended to overhang the ML width. Therefore, the use of a gender-specific implant for women was suggested. In contrast, there were some cases in which the femoral component tended to be undersized compared with the ML width in men. [Fig. 1] For Japanese women, the use of a gender-specific component should be considered. Additionally, there is a need for further investigation of gender-specific components in men

Introduction. The aim of this radiographic study was to define the anatomical axis joint centre distance (aJCD) and anatomical axis joint centre ratio (aJCR) of the distal femur in the coronal plane for skeletally mature individuals. Materials and Methods. A cross-sectional radiographic study was conducted to calculate the horizontal distances between the anatomical axis and the centre of the knee at the level of the intercondylar notch and the joint line. Ratios relating these points to the width of the femur were then calculated. Results. A total of 164 radiographs were included: 91 male (55.5%) and 73 female patients (44.5%) with a mean age of 44.9 ± 18.0 years, with 79 right (48.2%) and 85 left (51.8%). The intercondylar width mean was 75.4 ± 6.8mm, the median aJCD at the notch was 3.6mm (interquartile range, IQR 2.1 – 5.1), the median aJCD at the joint line was 4.7mm (IQR 3.5 – 6.3), the aJCR at the notch 45.1 ± 2.7, and the aJCR at the joint line 43.5 ± 2.7. The intercondylar width was significantly different (p<0.001) between males (79.5 ± 5.0 mm) and females (70.4 ± 5.1 mm). A significant difference between the aJCR at the notch (p=0.003) and the aJCR at the joint line (p=0.002) was observed in males and females. No differences between the aJCD at the notch or aJCD at the joint line was observed between males versus females, left versus right and those younger versus those older than 65 years. Conclusions. This is the first objective description of the anatomic axis joint centre ratio (aJCR) of the distal femur in the coronal plane. This ratio can be used to aid the planning and execution of distal femoral deformity correction, retrograde femoral nailing, and total knee arthroplasty

Purpose. The purpose of this study is to analysis and compare the micro-structural and mechanical properties of subchondral trabecular bone of non-osteoarthritic and osteoarthritic distal femur using a micro-images based on finite element analysis. Materials and Methods. Fifteen distal femur were harvested from the eight cadevers(5 males, 3 females; non-OA, 10, OA, 5). The subchondral trabeculae were obtained from the middle of artticular surface of distal femurs(Fig. 1). Cylinderical saw with 10 mm diameter was used to acquire trabecular bone core. Total 15 specimens were scanned using micro-CT (SkyScan-1172, SKYSCAN, Belgium) at 24.9ãŽ> of spatial resolution under 70ãŽ,'s voltage and current of 141ãŽ,. 2-D images with were established by an imaging software (TomoNT, SKYSCAN, Belgium) as shown in Fig. 2. Histomorphologic index, trabeculae thickness (Tb.Th), trabecular separation (Tb.Sp), bone volume (BV), bone volume fraction (BV/TV), structure model index(SMI) were determined by the ANT software (Table 1). Based on 2-D images, a finite element model was reconstructed (Fig. 3). Finite element analysis was done using BIONIX (CANTIBIO, Suwon, Korea). Yield stress (MPa), Stiffness was calculated with ANSYS 10.0(ANSYS, Inc) (Fig. 4). Results. The descriptive statistics of the microstructural and mechanical parameters are presented in Fig. 4. The results showed that trabecular bone of osteoarthritic distal femur had a decrease in Tb.Th, BV/TV and had an increase in Tb.Sp and SMI than non-osteoarthritic group. There was a decrease in the yield stress. Conclusion. The results of bone morphometry index and strength showed that subchondral trabeculae of osteoarthritic group was more degenerative structure and decreased strength. And, this results are contribution to understand the osteoarthritic change in bone remodeling aspect

Purpose. Rotationplasty was first described in 1930 by Borggreve for treatment of limb shortening with knee ankylosis after tuberculosis. In 1948, Van Nes described its use for management of congenital defects of the femur and in the 1980s, Kotz and Salzer reported on patients with malignant bone tumors around the knee treated by rotationplasty as an alternative to above-knee amputation. Currently, rotationplasty is one of the options for surgical management of lower extremity bone sarcomas in skeletally immature patients but alternative limb salvage techniques, such as the use of expandable endoprosthesis, are also available. Despite rather satisfactory functional results have been uniformly associated with rotationplasty, concern still exists about the potential psychological impact of the new body imagerelated to the strange appearance of the rotated limb. Results of rotationplasty for sarcomas of the distal femur over a 20-year period were analyzed, focusing on long-term survival, function, quality of life and mental health. Method. Retrospective study of 73 children who had a rotationplasty performed at two institutions between 1984 and 2007 for a bone sarcoma of the distal femur; 42 males and 31 females, mean age at surgery 8.7 yrs (range 3–17). Four patients were converted to transfemoral amputation due to early vascular complication; 25 eventually died of their disease (mean survival 34 months, range 4–127). The 46 remaining survivors were evaluated for updated clinical outcome, MSTS score, gait analysis, SF-36 score, quality of life interview and psychological assessment at mean follow-up of 15 yrs (range 3–23). Results. Overall survival was 64%. All the survivors were disease-free at last follow-up. Four patients required hardware revision for nonunion and subsequently healed. Three patients refused participation in the long-term follow-up study. Mean MSTS score was 79 (range 64–88). SF-36 score was obtained in 35 patients (age > 16); male patients showed a trend toward greater activity and vitality. Compared to age-group norms, rotationplasty scores were lower for physical activity level (p <0.05) and higher for general health perception (p = 0.05) and mental health (p < 0.05). Conclusion. Rotationplasty remains a durable reconstructive option with good long-term function and acceptable psychological impact for children with bone sarcomas of the distal femur

In total knee arthroplasty (TKA) the implant design is one key factor for a proper functional restoration of the diseased knee. Therefore, detailed knowledge on the shape (morphology) is essential to guide the design process. In literature, the morphology has been extensively studied revealing differences, e.g. between ethnicity and gender. However, it is still unclear in which way gender-specific morphological differences are sexual dimorphism or explained by differences in size. The aim of this study was to investigate the morphology of the distal femur under gender-specific aspects for a large group of patients. Statistical analysis was used to reveal significant differences and subsequent correlation analysis to normalise the morphology. A dataset of n=363 segmented distal femoral bone surface reconstructions (229 female, 134 male) were randomly collected from a database of patients which underwent TKA. In total, 34 morphological features (distances, angles), quantifying the distal femoral geometry, were determined full automatically. Subsequently, graphs and descriptive statistics were used to check normality and gender-specific differences were analysed by calculating the 95% confidence intervals for women and men separately. Finally, significant differences were normalised by dividing each feature by appropriate distance measurements and confidence intervals were recalculated. Looking at the confidence 95% intervals, 6 of 34 features did not show any significant differences between genders. Remarkably, this primarily involves angular (relative) features whereas distance (absolute) measurements were mostly gender dependent. Then, we normalised all distance measurements and radii according to their direction of measurement: Features defined in medial/lateral (ML) direction were divided by the overall ML width and those following the anterior/posterior direction were normalised based on the overall AP length. The results demonstrated that gender-specific differences mostly disappear by using an adequate normalisation term. In conclusion, implant sizes (femoral components) should not be linearly scaled according to one dimension. Instead, ML and AP directions should be regarded separately (non-isotropic scaling). Taking this into consideration, gender- specific differences might be neglected

Correct rotational alignment of the femoral component is one of the most important elements in successful total knee arthroplasty. The surgical epicondylar axis is a well-known reliable landmark for a total knee arthorplasy. However, sometimes it is difficult for surgeon to define where a sulcus is, thus, hard to define a surgical epicondylar axis during a surgery. This Study evaluated the new reference of axis “Lateral Condylar Axis (LCA)” for the distal femur. The LCA is defined by the angle between the surgical epicondyalr axis and the Lateral Condylar Axis. To evaluate the consistency of this angle through ages, genders and femoral-tibia angle, this study also measured the angles between the surgical epicondylar and the anteroposterior asix and the surgical epicondylar and the posterior condaylar axis. By evaluating out the correlations and comparing the figure between measurements using the Student test, this study suggests that the Lateral Condylar Axis is a reliable landmark to properly rotate the femoral component and is easier to define during a surgery. The 59 knees out of 41 patients data was measured in 2011 – 2012

Background. Recent anthropometric studies have suggested that current design of total knee arthroplasty (TKA) does not cater to racial anthropometric differences. The purpose of this study was to investigate the exact sizing and rotational landmarks of the distal femur collected and its gender differences from a large group of healthy Southern Chinese using 3D-CT measurements, and then compare these measurements to the five total knee prostheses conventionally used in China. Methods. This study evaluated distal femoral geometry in 85 healthy Southern Chinese, included 39 females (78 knees) and 46 males (92 knees) with a mean age of 33.9 years，a mean height of 164.7 cm and a mean weight of 59.9 kg. The width of the articular surface as projected onto the transepicondylar line(ML), anteroposterior dimension (AP), the dimensions from medial/lateral epicondyle to posterior condylar (MEP/LEP) were measured. A characterization of the aspect ratio (ML/AP) was made for distal femur. The angles between the tangent line of the posterior condylar surfaces, the Whiteside line, the transepicondylar line, and the trochlear line were measured. The sulcus angle and hip center-femoral shaft angle were also measured [Fig. 1]. The data were compared with the five total knee prostheses conventionally used in China. In analyzing the data, best-fit lines were calculated with use of least-squares regression. The dimensions are summarized as the mean and standard deviation. Comparisons of dimensions between males and females were made with use of the two-sample t test. A p value of <0.05 indicated a significant effect. Results. Within the population, males had larger ML, AP values and aspect ratio than females (ML: 70.44±3.04 vs. 61.40±2.62 mm, P<0.001; AP: 62.26±2.93 vs. 56.49±2.88 mm, P<0.001; 1.06±0.05 vs. 1.11±0.03, P<0.001). In addition, we found a gradual decrease in the aspect ratio corresponding to an increase in AP dimension, as seen in other studies. The transepicondylar axis was a reliable landmark to properly rotate the femoral component, so we used the MEP and LEP evaluate posterior condylar offset, the values were respectively 28.90±3.00 mm and 22.73±2.67 mm. However, most angles were almost the same between males and females. To evaluate the suitability shape of the femoral components currently used in China, we drawed and calculated best-fit lines for the AP, ML dimensions and aspect ratios of the femur and the five prostheses. For females, there was a significant association between the prostheses size and the amount of overhang, the femoral prostheses for females tended to be too large for a given AP dimension, with larger sizes having more overhang, especially in ML dimensions. In males, the morphologic data tended to be bigger than the prosthetic designs in the ML dimension for a given AP dimension, the femoral aspect ratio was higher for smaller knees and proportionally lower for larger knees[Fig. 2, 3]. Conclusion. Because dimensions of the distal femur and the aspect ratio tend to be smaller in Southern Chinese populations, whereas sulcus angles tend to be larger, designs for knee implants should be modified to improve the outcome of surgical treatment in this population

Background. Recent anthropometric studies have suggested that current design of total knee arthroplasty (TKA) does not cater to racial anthropometric differences. The purpose of this study was to investigate the exact sizing and rotational landmarks of the distal femur collected from a large group of healthy Southern Chinese using three dimensional computer tomographic measurements, and then compare these measurements to the known dimensions from Caucasian populations. Methods. This study evaluated distal femoral geometry in 125 healthy Southern Chinese, included 58 women (106 knees) and 67 men (134 knees) with a mean age of 35.2±8.11 years, a mean height of 165.5±7.94 cm, and a mean weight of 61.7±9.56 kg. The width of the articular surface as projected onto the transepicondylar line(ML), anteroposterior dimension (AP), the dimensions from medial/lateral epicondyle to posterior condylar (MEP/LEP)were measured. A characterization of the aspect ratio (ML/AP) was made for distal femur[Fig. 1]. The angles between the tangent line of the posterior condylar surfaces, the Whiteside line, the transepicondylar line, and the trochlear line were measured. The sulcus angle and hip center-femoral shaft angle were also measured. Known dimensions from Caucasian populations were compared with the morphologic data collected in this study[Fig. 2]. In analyzing the data, best-fit lines were calculated with use of least-squares regression. The dimensions are summarized as the mean and standard deviation. The differences of rotational landmarks and sizing between the Southern Chinese and Caucasians were assessed with use of the Student t test. A p value of <0.05 indicated a significant effect. Results. Within the Southern Chineses population, males had larger ML and AP values than females (ML: 70.38±3.09 vs. 62.09±2.52mm, P<0.001; AP: 63.68±2.82 vs. 57.83±2.91mm, P<0.001). The results also showed that Southern Chinese knees were generally smaller than Caucasian (ML: 67.27±4.95 vs. 76.8±7.2mm, P<0.001). The femoral aspect ratio of Southern Chinese was significantly smaller than Caucasian (1.09±0.04 vs. 1.28±0.06, P<0.001). In addition, we found a gradual decrease in the aspect ratio corresponding to an increase in anteroposterior dimension in the distal femur of Southern Chinese, as seen in most other studies. The transepicondylar axis was found to be a reliable landmark to properly rotate the femoral component, so we used the femoral condylar MEP and LEP evaluate posterior condylar offset, the values were respectively 28.62±2.18mm and 22.50±2.19mm. From this study, most of the angles were different from Caucasian. Anteroposterior line minus epicondylar line angle was 90.14±1.30° (Caucasian 90.33±2.44°, P>0.05), anteroposterior line minus posterior condylar line angle was 83.18±1.94° (Caucasian 86.82±2.71°, P<0.001), epicondylar line minus posterior condylar line angle was 7.00±1.70° (Caucasian 3.60±2.02°, P<0.001), trochleoepicondylar angle was 12.45±2.34°(Caucasian 4.95±2.15°, P<0.001), sulcus angle was 147.40±4.69° (Caucasian 139.6±6.96°, P<0.001). The angle between mechanical and anatomic axis of the femur was 5.92±0.47°(Caucasian 6.33±2.42°, P<0.001). Conclusion. Because dimensions of the distal femur and the aspect ratio tend to be smaller in Southern Chinese populations, whereas sulcus angles tend to be larger, designs for knee implants should be modified to improve the outcome of surgical treatment in this population. The Larger epicondylar line minus posterior condylar line angles, and the smaller angle between mechanical and anatomic axis seen in Southern Chinese populations also requires us to pay particular attention to surgical technique, in order to ensure patient safety

Introduction. The constitutional knee anatomy in the coronal plane includes the distal femoral joint line obliquity (DFJLO) which in most patients is in slight valgus positioning. Despite this native anatomy, the mechanical positioning of the femoral component during primary total knee arthroplasty (TKA) often ignores the native DFJLO opting to place the femur in a set degree of valgus that varies upon the practitioner's practice and experience. Unfortunately, this technique is likely to generate high rate of distal lateral femoral overstuffing. This anatomical mismatch might be a cause of anterior knee pain and therefore partly explain the adverse functional outcomes of mechanically aligned (MA) TKA. Our study aims at assessing the relationship between constitutional knee anatomy and clinical outcomes of MA TKA. We hypothesized that a negative relationship would be found between the constitutional frontal knee deformity, the distal femoral joint line obliquity, and functional outcomes of MA TKA with a special emphasize on patellofemoral (PF) specific outcomes. Methods. One hundred and thirteen patients underwent MA TKA (posterior-stabilized design) for primary end-stage knee osteoarthritis. They were prospectively followed for one year using the New KSS 2011 and HSS Patella score. Residual anterior knee pain was also assessed. Knee phenotypes using anatomical parameters (such as HKA, HKS, DFJLO and LDFA (Lateral distal femoral angle)) were measured from preoperative and postoperative lower-limb EOS® images (Biospace, Paris, France). We assessed the relationship between the knee anatomical parameters and the functional outcome scores at 1 year postoperatively. Results. We investigated four groups according to the preoperative obliquity of the distal femur and HKA. The group with high DFJLO and varus knee deformity demonstrated lower HSS scores (drop>10%, p=0.03) and higher rate of anterior knee pain (p=0.03). Higher postoperative variation of LDFA was associated with lower HSS scores (r = −0.2367, p=0.03) and with higher preoperative DFJLO (p=0.0001) due to the MA technique. Knee phenotypes with LDFA<87° presented higher risk of variation of LDFA. No correlation was found using New KSS 2011 outcomes at one-year follow-up. Discussion/Conclusion. Disregard of the constitutional knee anatomy (LDFA and DFJLO) when performing a MA TKA may generate a non-physiologic knee kinematics that impact patellofemoral outcomes and resulting in residual anterior knee pain. While these results are restricted to modern posterior-stabilized TKA design, recent in silico and in vitro studies supported the negative effect of the lateral overstuffing of the femoral component in the coronal plane during knee flexion. This study provides further evidence that suggest patient-specific anatomical considerations are needed to optimize component position and subsequent outcomes following primary TKA. Additional studies are needed to integrate the rotational status of the femoral component in this analysis. For any figures or tables, please contact authors directly

Aims/Hypothesis. The aims of this study were: 1) to quantitatively analyse the amount of knee extension that is achieved with +2mm incremental increases in the amount of distal femoral bone that is resected during TKA in the setting of a flexion contracture, 2) to quantify the amount of coronal plane laxity that occurs with each 2mm increase in the amount of distal femur resected. In the setting of a soft tissue flexion contracture, we hypothesized that although resecting more distal femur will reliably improve maximal knee extension, it will ultimately lead to increased varus and/or valgus laxity throughout mid-flexion. Methods. Seven fresh-frozen cadaver legs from hip-to-toe underwent TKA with a posterior stabilized implant using a measured resection technique with computer navigation system equipped with a robotic cutting-guide, in this IRB approved, controlled laboratory study. After the initial tibial and femoral resections were performed, the posterior joint capsule was sutured (imbricated) through the joint space under direct visualization until a 10° flexion contracture was obtained with the trial components in place, as confirmed by computer navigation. Two distal femoral recuts of +2mm each where then subsequently made and after the remaining femoral cuts were made, the trail implants were reinserted. The navigation system was used to measure overall coronal plane laxity by measuring the mechanical alignment angle at maximum extension, 30°, 60° and 90° of flexion, when applying a standardized varus/valgus load of 9.8 [Nm] across the knee using a 4kg spring-load located at 25cm distal to the knee joint line.(Figure 1) Coronal plane laxity was defined as the absolute difference (in °) between the mean mechanical alignment angle obtained from applying a standardized varus and valgus stress at 0°, 30, 60° and 90°. Each measurement was performed three separate times and averaged. The maximal extension angle achieved following each 2mm distal recut was also recorded. Two-tailed student's t-tests were performed to analyze whether there was difference in the mean laxity at each angle and if there was a significant improvement in maximal extension with each recut. P-values < 0.05 were considered significant. Results. For a 10° flexion contracture, performing the first distal recut of +2mm increased overall coronal-plane instability by approximately 3° at 30° and 60° of flexion (p < 0.05).(Figure 2) Performing the second recut of +4mm further increased mid-flexion instability by another 2° (p < 0.01).(Figure 2) Maximum extension increased from 10° of flexion to 6.4° (±2.5° SD, p < 0.005) and to 1.4° (±1.8° SD, p < 0.001) of flexion with each 2mm recut of the distal femur. Conclusions. Using a reliable, accurate, and reproducible method of measuring coronal plane laxity and maximal knee extension, we have shown that in the setting of a flexion contracture or tight extension space during TKA, recutting the distal femur by 2 mm will effectively increase the amount of maximal extension by 4°; however, as a secondary effect, recutting the distal femur by 2 mm will also lead to 2.5° of increased coronal plane laxity in midflexion

Purpose of study:. Up to 30% of distal femur fractures treated with a locked plate have problems with union. Distal femur locked plates have become a very popular means of internal fixation because of their ability to provide stable distal peri-articular fixation. In spite of this enthusiasm however several studies have reported significant problems with healing. In the distal femur it is recognized that locked plate fixation may be too rigid if used in certain configurations preventing the essential micro movement required for biological healing. Implant failure may arise from rigid configurations that cause excessive hardware stress concentrations. In an attempt to address these problems longer plates and an increased working length have been proposed to reduce construct rigidity. The purpose of our study is to investigate whether an increased working length translates into improved healing. Description of method:. We undertook a retrospective review of 92 consecutive cases performed at our institution from 2007–2010. Case notes and X-rays were reviewed. Working length, plate to fracture zone ratios and working length to fracture zone ratios were calculated. Union was assessed radiographically and clinically. Covariates of smoking, age, sex and fracture severity were included. Outcomes considered were union or established non-union. Delayed union was defined as union after 20 weeks. Summary of results:. Median time to union was 16.9 weeks. 11 delayed unions (23.4%, 95%CI(10.8–36.0%)), 3 non-unions (6.4% 95%CI(0.0–13.6%)) and no implant failures were recorded. Our data are consistent with the previously reported proportion of distal femur fractures treated with a locked plate that have problems with union. Although trends were present, no significant associations between impaired healing and exposure variables were found. Conclusion:. While biomechanical studies have demonstrated increased flexibility of longer plates with an increased working length, clinically this did not translate into significantly improved fracture healing in our study

Purpose. The purpose of this study is to investigate the relationship between the angles made by the reference axes on the computerized tomography (CT) images and comparison of the knee alignment between healthy young adults and patients who is scheduled to have total knee arthroplasty. Materials and Methods. This study was conducted in 102 patients with osteoarthritis of knee joint who underwent preoperative computerized tomography (CT). The control group included 50 patients having no arthritis who underwent CT of knee. Axial CT image of the distal femur were used to measure the angles among the the anteroposterior (AP) axis, the posterior condylar axis (PCA), clinical transepicondylar axis (cTEA) and the surgical transepicondylar axis (sTEA). Then, the differences in amounts of rotation between normal and osteoarthritic knee was evaluated. Results. The mean angle between cTEA and PCA in the osteoarthritis group was 5.0°±2.2, whereas that in the control group was 5.5°±2.0. The mean angle between cTEA and sTEA in the osteoarthritis group was 3.7°±0.8, whereas that in the control group was 4.3°±0.6. The mean angle between AP axis and PCA in the osteoarthritic group was 93.25°±2.0, whereas in the control group was 96.3°±1.9. There was significant differences in angles between AP axis and PCA. But, no significant difference was seen in angles between cTEA and PCA, cTEA and sTEA in two groups. Conclusion. In result of this study, the angle between cTEA and PCA showed an average external rotation of 5.0° in osteoarthritic group. More external rotation was needed for the femoral component alignment than 3° recommended in usual total knee arthroplasty. The angle between AP axis and PCA is decreased in osteoarthritic knee compared with normal knee. But, osteoarthritic change of knee joint had no significant effect on the relationships of other axes

[Objective]. The objectives of this study are to measure the morphometric parameters of pre-operative distal femur in Japanese patients who received TKA, to investigate the differences in distal femoral anatomy between the genders, and to compare the measurements with the dimensions of femoral implants current used in Japan. [Methods]. One-hundred seventy-nine Japanese patients who underwent TKA in Osaka Koseinenkin Hospital from April, 2009 to December, 2011 were included in this study. The genders and diagnoses were 25/ 154 patients (male/ female) and 143/ 36 patients [osteoarthritis (OA)/ rheumatoid arthritis (RA)], respectively. The mean age, height and body weight were 73.2 years, 152.2 cm and 56.7 kg, respectively. We measured the AP length, ML width, aspect ratio angle of distal femur. The measurement points on the medial condyle was 10 mm and on the lateral condyle was 8 mm from the lowest points of the medial and lateral posterior condyle to stimulate the optimal cutting thickness. We evaluated the relationship between AP length and ML width, or aspect ratio and ML width in diagnosis, alignment and gender. We also compared the measurements with the dimensions of femoral implants current used in Japan. Continuous variables were assessed using the Mann-Whitney's U test. Relationship between AP length and ML width, or aspect ratio and ML width were assessed using simple regression analysis. Regression lines were assessed using analysis of covariance. For all tests, probability values (p values) of < 0.05 were considered to indicate statistical significance. [Results]. The mean AP length, ML width, aspect ratio, SEA/PCA angle and Whiteside/SEA angle were 58.8 mm, 64.7 mm, 0.91, 3.5 degrees of external rotation and 1.6 degrees of external rotation, respectively. The both relationship between AP length and ML width, and aspect ratio and ML width were significant (p < 0.001). As the ML width was getting longer, AP length was getting shorter and aspect ratio was getting lower. Although analysis of covariance between OA and RA in the relationship between aspect ratio and ML width was not significant (p = 0.955), that of valgus alignment [femorotibial angle (FTA) < 170 degrees] and varus alignment (FTA > 176 degrees) were significant (p = 0.003). The AP length, ML width in male (63.6 mm, 72.7 mm) were longer than those in female (58.1 mm, 63.4 mm), and aspect ratio in male (0.88) were lower than that in female (0.92) significantly (all p < 0.001). Although analysis of covariance between male and female in the relationship between AP length and ML width, and aspect ratio and ML width were not significant (p = 0.985 and 0.555). [Conclusion]. The aspect ratio showed a higher ratio for smaller knees and a proportionally lower ratio for lager knees in Japanese. The tendency of aspect ratio change with ML width was different between valgus and varus alignment. As the tendency of aspect ratio change with ML width was not different between male and female, the gender difference of aspect ratio was related to the difference of skeleton size (ML width) between male and female