Objective. In this study, we aim to compare total bone amount extracted in total knee arthroplasty in implant design and the bone amount extracted through intercondylar femoral notch cut. Material and Method. In this study, we implemented 10 implants on a total of 50 sawbones from 5 different total knee arthroplasty implant brands namely Nex-Gen Legacy (Zimmer, Warsaw, IN, USA), Genesis 2 PS (Smith&Nephew, Memphis, TN, USA), Vanguard (Biomet Orthopedics Inc., Warsaw, IN, USA), Sigma PS (De Puy, Johnson&Johnson, Warsaw, IN, USA), Scorpio NRG PS (Stryker Co., Kalamazoo, USA). Equal or the closest sizes of each brand on anteroposterior plane were selected, and cuts were made following standard technique(see Fig 1 and 2). Extracted bone pieces were measured in terms of volume and length on three planes, and statistically analysed. The volume of all pieces available after each femoral incision was measured according to Archimedes’ principles. Furthermore, the volume of each intercondylar femoral notch pieces was measured separately from other pieces but with the same method. The measurement of intercondylar femoral notch pieces on 3 planes (medial-lateral, anterior-posterior, superior-inferior) was made using Kanon slide gauge (Ermak Ltd, Istanbul, TR). Femoral notch incision pieces were scanned with CAD/CAM technology using three-dimensional scanner 1 SeriesTM (Dental Wings Inc, Montreal, QC, Canada), and the measurements were confirmed with DWOS CAD 4.0.1 software (Dental Wings Inc, Montreal, QC, Canada)(see figure 3a-e). The volume of 10 intercondylar femoral notch pieces performed through the set of each brand was averaged, and considered as the incision volume of that particular brand. Results. The comparison made by excluding femoral notch cuts did not produce any statistically significant difference between the amounts of bone extracted. The least volumetric value measured in extracted intercondylar femoral notch cut was obtained using Vanguard (3,6±0,4 cm3). The gradually increasing volumes were obtained from Nex-Gen (3,7±0,5 cm3), Sigma (5,7±0,4 cm3), Genesis 2 (6,3±0,3 cm3) and Scorpio NRG (6,7±0,7 cm3), respectively. There was no statistical difference between Genesis 2 and Scorpio NRG, and between Nex-Gen and Vanguard. Conclusion. There are significant differences among implant designs in terms of preserving bone stock, and much of these differences stems from intercondylar femoral notch incision

Purpose. The purpose of this study was to determine whether intra-operative identification of osseous ridge anatomy (lateral intercondylar “residents” ridge and lateral bifurcate ridge) could be used to reliably define and reconstruct individuals' native femoral ACL attachments in both single-bundle (SB) and double-bundle (DB) cases. Methods. Pre-and Post-operative 3D, surface rendered, CT reconstructions of the lateral intercondylar notch were obtained for 15 patients undergoing ACL reconstruction (11 Single bundle, 4 Double-bundle or Isolated bundle augmentations). Morphology of native ACL femoral attachment was defined from ridge anatomy on the pre-operative scans. Centre's of the ACL attachment, AM and PL bundles were recorded using the Bernard grid and Amis' circle methods. During reconstruction soft tissue was carefully removed from the lateral notch wall with RF coblation to preserve and visualise osseous ridge anatomy. For SB reconstructions the femoral tunnel was sited centrally on the lateral bifurcate ridge, equidistant between the lateral intercondylar ridge and posterior cartilage margin. For DB reconstructions tunnels were located either side of the bifurcate ridge, leaving a 2mm bony bridge. Post-operative 3D CTs were obtained within 6 weeks post-op to correlate tunnel positions with pre-op native morphology. Results. Pre-op native ACL attachment site morphology was very similar to previous in-vitro studies: the mean centre was found at 27% along Blumensaat's line (range 19-33%) and 38% the width of the lateral femoral condyle (range 31-43%). Despite the variability between individuals there was close correlation between pre-operative localization of the femoral attachment centre and position of single bundle ACL reconstructions tunnels on the post-op CT (R=0.92). Similar results were observed for double-bundle and isolated bundle augment reconstructions. Conclusion. ACL attachment site morphology varies between individuals. Intra-operative localization of the osseous landmarks (lateral intercondylar and bifurcate ridges) appears to lead to accurate, individualised anatomical tunnel placement whether using single or double-bundle reconstruction techniques

Introduction: Bone resorption at the bone-implant interface is still a problem, leading to pain, poor function and the possibility of bone fracture. This loss of supporting bone tissue is due to resorption and impaired bone formation. Loosening of an implant is often not clinically or radiographically apparent for 8–10 years. It would be beneficial if these potential failures could be identified early so that revision surgery can be avoided. The aim of this study was to investigate the influence of implant material property changes and its influence on the trabecular loading patterns of the underlying supporting bone structure. Methods: An intact and reconstructed 3D finite element (FE) model of a human femur was developed. The model was generated using PATRAN and CT scans. This was used to determine the stress, strain and interface sliding of a knee implant at heel-strike and stair climbing phases of gait. FE analysis of the model was performed using ABAQUS software. The materials properties of the bone were extracted from the CT data and applied using FORTRAN subroutines. Implant-bone interfaces were simulated using cementless fixation concepts. Sliding contact conditions were applied to simulate the immediate post-operative period. Results: Three material property cases were analysed, with respect to the intact bone, at 100%, 25% and 2.5% of cobalt chrome’s (CoCr) Youngs modulus. At heel-strike, for the 100% case, higher stress was found at anterior flange while lower stress dominated around the pegs and intercondylar notch. For the 25% case, lower stresses were found in the intercondylar notch and higher stresses above the pegs. For the 2.5% case, stresses resembled that of intact bone, higher stresses were found above the pegs and lower stress in the intercondylar notch. In stair-climbing, for the 100% case, lower stresses were found around the pegs and in the intercondylar notch. For the 25% case, lower stresses were found in the intercondylar notch and higher stresses in areas above the pegs. For the 2.5% case, higher stresses were found at the distal condyles and lower stresses were observed in the intercondylar notch. Discussion: The analysis presented changes in the trabecular loading and subsequently resulted in stress shielding. The general trend showed that the majority of stress shielding is occurring at the posterior flange and medial condyle while increased trabecular loading occurred at the anterior flange and lateral condyle regions. As the stiffness of the implant decreases from 100% to 25%, the differences in trabecular loading are extremely small. Both these implant material properties are very stiff in comparison to the underlying trabecular bone. However, as CoCr stiffness is decreased to 2.5% this yields a more homogenous stress distribution at the contact interfaces

Introduction: Appropriate femoral component alignment is important for long-term survival of total knee arthroplasty (TKA). Valgus angle of femoral component is recommended as the angle between mechanical axis and anatomical axis of the femur. Intramedullary guide system is widely used for determining the valgus positioning of femoral component. Entry point of intramedullary guide is one of the key factors for determining valgus angle of femoral component. Some investigators have shown appropriate entry points of intramedullary guide, however, it is still unclear. In this study, appropriate entry point of intramedullary guide system was calculated using three-dimensional digital templating software “Athena” (Soft Cube, Osaka, Japan). Method: Forty-one knees in 34 osteoarthritis patients except valgus deformity (30 females and 4 males, mean age 75.1 years) received TKA and were simulated using “Athena” from January 2009 to March 2009. All cases were grade III or IV in Kellgren-Lawrence index. Radiograph and CT scan image were used for determination of appropriate entry point of femur using “Athena”. The anatomical axis of femur was defined as a line connecting the midpoints of femoral AP and lateral diameter, at 60 mm and 110 mm proximal to the center of intercondylar notch. Two coordinate systems were configured as representation of entry points. One was at the center of intercondylar notch defined as the point of origin in axial view of CT image and the line parallel to the clinical epicondylar axis (cTEA) defined as X-axis. Another coordinate system was the same point of origin but parallel to the line between trochlear groove and the center of intercondylar notch (AP line) defined as Y-axis. Result: In the coordinate system that defined the cTEA as the X-axis, the average of entry point was 0.3± 0.30 mm medial (range, −4.8~ 4.7mm) and 11.6 ± 0.52mm anterior (range, 3.1~ 16.5mm) to the center of intecondylar notch. In the other coordinate system that defined AP line as the Y-axis, the average of entry point was 2.6± 0.29 mm medial (range, −1.5~ 6.3mm) and 11.2±0.52 mm anterior (range, 2.8~ 16.0mm) to the center of intercondylar notch. Discussion: In this study, the appropriate entry point of intramdullary guide was slightly medial and about 11mm anterior to the center of intercondylar notch on average. However, individual entry point varied considerably in distance. These data indicates that it is important to simulate the appropriate entry point of intramedullary guide in preoperative planning

Patellofemoral complaints are the common and nagging problem after total knee arthroplasty. Crepitus occurs in 5% to over 20% of knee arthroplasty procedures depending on the type of implant chosen. It is caused by periarticular scar formation with microscopic and gross findings indicating inflammatory fibrous hyperplasia. Crepitus if often asymptomatic and not painful, but in some cases can cause pain. Patella “Clunk Syndrome” is less common and represents when the peripatella scarring is abundant and forms a nodule which impinges and “catches” on the implant's intercondylar notch. Patella Clunk was more common with early PS designs due to short trochlear grooves with sharp transition into the intercondylar notch. Clunks are very infrequent with modern PS implants. This syndrome has been reported in CR implants as well. Thorough debridement of the synovium and scarring at the time of arthroplasty is thought to reduce the occurrence of crepitus and clunks. Larger patella with better coverage of the cut bone may also be helpful. The diagnosis can be made on history and physical exam. X-rays are also helpful to assess patella tracking. MRI or ultrasound can be used to identify and confirm the diagnosis, but this is not mandatory. Painful crepitus and clunk syndrome that fail conservative management of NSAIDS and physical therapy may require surgery. Both crepitus and clunk can be treated with arthroscopic removal of the peripatella scar. Patella maltracking should also be assessed and treated. While recurrence may occur, it is uncommon

Failure of osseointegration and periprosthetic joint infection (PJI) are the two main reasons of implant failure after total joint replacement (TJR). Nanofiber (NF) implant surface coating represents an alternative local drug eluting device that improves osseointegration and decreases the risk of PJI. The purpose of this study was to investigate the therapeutic efficacies of erythromycin (EM)-loaded coaxial PLGA/PCL-PVA NF coating in a rat S. aureus-infected tibia model. NF coatings with 100mg and 1000mg EM were prepared. NF without EM was included as positive control. 56 Sprague Dawley rats were divided into 4 groups. A titanium pin (1.0-mm x 8 mm) was placed into the tibia through the intercondylar notch. S. aureus (SA) was introduced by both direct injection of 10 μl broth (1 × 10. 4. CFU) into the medullary cavity and single dip of Ti pins into a similar solution prior to insertion. Rats were sacrificed at 8 and 16 weeks after surgery. The outcome measurements include μCT based quantitative osteolysis evaluation and hard tissue histology. Results: EM-NF coating (EM100 and EM1000) reduced osteolysis at 8 and 16 weeks, compared to EM0 and negative control. The effective infection control by EM-NFs was further confirmed by hard tissue section analysis. The Bone implant contact (BIC) and bone area fraction Occupancy (BAFO) within 200 µm of the surface of the pins were used to evaluate the osseointegration and new bone formation around the implants. At 16 weeks, the bone implant contact (BIC) of EM 100 (35.08%) was higher than that of negative control (3.43%) and EM0 (0%). The bone area fraction occupancy within 200 µm (BAFO) of EM100 (0.63 mm2) was higher than that of negative control (0.390 mm2) and EM0 (0.0 mm. 2. ). The BAFO of EM100 was also higher than that of EM1000 (0.3mm. 2. ). There was much less osteolysis observed with EM100 and EM1000 NF coatings at 16 weeks, as compared to EM0 positive control, p=0.08 and p=0.1, respectively. Osseointegration and periprosthetic bone formation was enhanced by EM-NFs, especially EM100. Data from this pilot study is promising for improving implant surface fabrication strategies

Patellofemoral complaints are the common and nagging problem after Total Knee Arthroplasty. Crepitus occurs in 5% to over 20% of knee arthroplasty procedure depending on the type of implant chosen. It is caused by periarticular scar formation with microscopic and gross findings indicating inflammatory fibrous hyperplasia. Crepitus if often asymptomatic and not painful, but in some cases can cause pain. Patella “Clunk Syndrome” is less common and represents a when the peripatella scarring is abundant and forms a nodule which impinges and “catches” on the implants intercondylar notch. Patella Clunk was more common with early PS designs due to short trochlear grooves with sharp transition into the intercondylar notch. Clunks are very infrequent with modern PS implants. This Syndrome has been reported in CR implants as well. Thorough debridement of the synovium and scarring at the time of Arthroplasty is thought to reduce the occurrence of crepitus and clunks. Larger patella with better coverage of the cut bone may also be helpful. The diagnosis can be made on history and physical exam. X-rays are also helpful to assess patella tracking. MRI or ultrasound can be used to identify and confirm the diagnosis but this is not mandatory. Painful crepitus and clunk syndrome that fail conservative management of NSAIDS and physical therapy may require surgery. Both crepitus and clunk can be treated with arthroscopic removal of the peripatella scar. Patella maltracking should also be assessed and treated. While recurrence may occur it is uncommon

Patellofemoral arthroplasty (PFA) has higher revision rates than total knee arthroplasty (TKA) [Van der List, 2015; Dy, 2011]. Some indications for revision include mechanical failure, patellar mal-tracking, implant malalignment, disease progression and persistent pain or stiffness [Dy, 2011; Turktas, 2015]. Implant mal-positioning can lead to decreased patient satisfaction and increased revision rates [Turktas, 2015]. Morphological variability may increase the likelihood of implant mal-positioning. This study quantifies the morphological variability of the anterior-posterior (AP) and medial-lateral (ML) aspects of the patellofemoral compartment using a database of computed tomography (CT) scans. The analysis presented here used the custom CT based program SOMA (SOMA V.4.3.3, Stryker, Mahwah, NJ). SOMA contains a large database of 3D models created from CT scans. Anatomic analysis and implant fitting tools are also integrated into SOMA to perform morphometric analyses. A coordinate system is established from the femoral head center, the intercondylar notch, and a morphological flexion axis (MFA). The MFA is created by iteratively fitting circles to the posterior condyles and creating and axis through the circles' centers. The sagittal plane is created normal to this axis and through the notch. A coronal plane is created from the femoral head center and the flexion axis. The AP measurement is taken normal to the coronal plane from the anterior cortex sulcus to the intercondylar notch (Figure 1). A 5°-flexed anterior resection is created to run-out at the anterior cortex sulcus. The ML measurement is taken normal to the sagittal plane from the most medial to the most lateral points of the anterior resection (Figure 1). The ML measurements are broken down into medial and lateral components divided by a sagittal plane through the trochlea. Means and standard deviations of the AP and ML measurements are calculated. The mean and standard deviation for the AP measurement are 24.9mm and 2.8mm, respectively. The data predicts that 99.7% of the population will have an AP measurement between 16.5mm and 33.3mm. The mean and standard deviation for the ML measurement are 54.6 mm and 5.5mm, respectively. The data predicts that 99.7% of the population will have an ML measurement between 38.1mm and 71.1mm A Pearson Correlation value of 0.134 was calculated for AP/ML indicating a very weak positive correlation between the measures. The correlation value and the large measurement ranges indicate that there is high variability between the AP and ML measurements. A scatterplot was created to graphically represent the high variability between the AP and ML width measurements (Figure 2). A Pearson Correlation value of −0.649 was calculated for the medial and lateral components of ML (Figure 3). The results of this study suggest that patellofemoral morphology is highly variable with respect to the AP and ML dimensions. This variability may impact implant fit and positioning and should be taken into consideration in the design and use of prostheses for PFA. For any figures or tables, please contact authors directly (see Info & Metrics tab above).

Background: Arthroscopic visualisation of the postero-medial and posterolateral compartments of the knee through the intercondylar notch using the anterolateral and anteromedial portals respectively is not commonly practiced. The purpose of this study was to prospectively evaluate whether these views are useful either diagnostically, therapeutically or both in a routine knee arthroscopy. Patients and Methods: It is a prospective study of two hundred consecutive patients who underwent a routine knee arthroscopy in our unit using the standard portals following an appropriate clinical and radiological evaluation. Posteromedial and posterolateral compartment visualisation through the intercondylar notch was undertaken in all the patients. An evaluation of the ease of the technique, the usefulness of visualisation and the morbidity associated with the procedure were recorded. Results: The technique was deemed simple to perform in 91% of the patients. It was found to be more difficult in knees with degenerative joint disease. Posteromedial and posterolateral compartment visualisation was found to be useful for diagnosis or treatment in 15% and 6% of the diagnosed conditions respectively. The technique was most useful for tears of the posterior horn of the medial meniscus, most of which were not detected by visualisation from the anteromedial compartment alone. Visualisation of the compartments was deemed adequate in 98% of the patients. There was no morbidity associated with this procedure. Conclusion: We believe that visualisation of the pos-teromedial and posterolateral compartment in a routine knee arthroscopy is beneficial; and an easy and safe procedure to perform

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

Introduction. Alignment and positioning of implants is important in total knee arthroplasty (TKA). Identifying the femoral hip center (FHC) without fluoroscopy or computer navigation is considered difficult. The Complete Compass system (CoCo) is a femoral extramedullary guidance system designed to identify the FHC. This apparatus provides an accurate representation of the femoral functional axis in the coronal plane without a computer navigation system. We compared postoperative implant alignment of patients undergoing total knee arthroplasty between CoCo and intraoperative computer navigation. Materials and Methods. Twenty-five consecutive TKAs using CoCo were analyzed. CoCo has a pivotal arm with a pivotal shaft arranged to extend perpendicular to the coronal plane. A marker is attached to the pivotal arm to depict a circular arc on the marking plate with rotation of the pivotal arm. The pivotal shaft is placed at the intercondylar notch of the femur. The distance from the pivotal shaft to the marker is equal to the distance from the intercondylar notch of the femur to the FHC of the patient based on preoperative measurements in the coronal plane. This apparatus has a level of the horizontal plane and the condition of the pivotal shaft is able to match neutral positions in the sagittal and axial planes. The intersection of two arcs drawn by using CoCo with the hip joint in abduction and adduction indicates the FHC position. Postoperative coronal and sagittal views radiographs were obtained. Twenty-five TKAs implanted using computer navigation were also analyzed for postoperative alignment. For two groups, targeted implant position was 90° in both planes for the femoral functional axis. Results. In the CoCo group, mean absolute difference between planned and actual femoral placement was 0.5° (standard deviation (SD), 0.7) in the coronal plane and 2.8° (SD, 1.3) in the sagittal plane. For the computer navigation group, mean difference from ideal placement for the femur was 0.6° (SD, 0.7) in the coronal plane and 2.2° (SD, 1.4) in the sagittal plane. In all comparisons, no significant differences were seen between CoCo and computer navigation. Conclusion. In this study, the Coco group achieved accurate alignment and implant positioning without computer navigation, and results were comparable to computer navigation TKA. CoCo is a simple system, and has the possibility to take the place of expensive computer navigation systems

Introduction We describe an arthroscopic technique of excising a lesion from within the posterior septum of the knee. To our knowledge this has not been described in the literature. Case History A 35-year old male taxi-driver presented with pain in the back of his right knee. Examination did not reveal any abnormality except pain on flexing the knee beyond 90-degrees. MRI showed a multiloculated ganglion in the posterior compartment of the knee. The ganglion was located within the posterior septum and successfully excised arthroscopically. 6-months postoperatively the patient is assyptomatic. Anatomy of the posterior septum The posterior septum is located between the posterior cruciate ligament (PCL) and the posterior capsule dividing the posterior cavity of the knee into seperate posteromedial and posterolateral compartments. It is triangular in shape, formed by the reflections of the synovium from the PCL. The Technique The posterior septum of the knee was approached through the intercondylar notch by the anterior portals. Slow and careful dissection was carried out in the V-shaped space between the anterior and the posterior cruciate ligaments. The synovium of the septum was resected and the space within the septum entered. The ganglion was successfully removed. There was no complication. The relatively central placement of the anterior portals is important to gain access to the posterior septum via the notch. Discussion and conclusion Intra-articular ganglion cysts are uncommon. Reported prevalence ranges from 0.2% to 1.3%. Ganglion cysts arising from the anterior and the posterior cruciate ligaments have been well described. The ganglion cyst within the posterior septum has not been reported. The anatomy of the posterior septum makes it inaccessible to routine arthroscopic examination. It has close proximity to the vascular structures. We approached the posterior septum from the anterior portals through the intercondylar notch. The ganglion was successfully excised

Introduction. Anteromedial osteoarthritis of the knee (anteromedial gonarthrosis-AMG) is a common form of knee arthritis. In a clinical setting, knee arthritis has always been assessed by plain radiography in conjunction with pain and function assessments. Whilst this is useful for surgical decision making in bone on bone arthritis, plain radiography gives no insight to the earlier stages of disease. In a recent study 82% of patients with painful arthritis had only partial thickness joint space loss on plain radiography. These patients are managed with various surgical treatments; injection, arthroscopy, osteotomy and arthroplasty with varying results. We believe these varying results are in part due to these patients being at different stages of disease, which will respond differently to different treatments. However radiography cannot delineate these stages. We describe the Magnetic Resonance Imaging (MRI) findings of this partial thickness AMG as a way of understanding these earlier stages of the disease. Method. 46 subjects with symptomatic partial thickness AMG underwent MRI assessment with dedicated 3 Tesla sequences. All joint compartments were scored for both partial and full thickness cartilage lesions, osteophytes and bone marrow lesions (BML). Both menisci were assessed for extrusion and tear. Anterior cruciate ligament (ACL) integrity was also assessed. Osteophytes were graded on a four point scale in the intercondylar notch and the lateral margins of the joint compartments. Scoring was performed by a consultant radiologist and clinical research fellow using a validated MRI atlas with consensus reached for disagreements. The results were tabulated and relationships of the interval data assessed with linear by linear Chi2 test and Pearson's Correlation. Results. All cases had medial femoral cartilage loss; 22% partial and 78% full thickness. 79% showed medial tibial loss, however in no cases was there medial tibial loss without femoral loss. 10 cases had lateral compartment partial thickness cartilage loss. Again, there was no tibial loss without femoral loss present. Increasing size of intercondylar notch osteophyte is associated with increasing ACL damage (p=0.001). Independent to this, increasing ACL damage is associated with lateral femoral condyle cartilage loss (p=0.002). Throughout the knee the incidence of BMLs increased with increasing cartilage loss (p=0.025). Only 13% of medial menisci were normal. As meniscal damage increases, so does the incidence of BMLs in the same compartment (p=0.03). Discussion. We describe the MRI findings of early AMG with partial thickness joint space loss. In all cases there was medial femoral loss, either with or without tibial loss. We believe the disease begins on the medial femoral condyle and progresses through the joint in stages. Later stages are associated with damage to the other structures in the knee, such as the meniscus and the ACL. Damage to the ACL is associated with increasing osteophytosis. This description is the first step in describing the stages of early AMG. Description of these stages is important since we believe the outcome of surgical intervention may be dependant on these and they may guide future therapy

Introduction. Intramedullary femoral alignment guide is mostly used in total knee arthroplasty (TKA). Accurate preoperative plan is critical to get good alignments when we use intramedullary femoral guide, because the center of femoral head cannot be looked directly during operation. Commonly, the planning is carried out using preoperative anteroposterior radiographs of the femur. The angles formed between mechanical axes of the femur and distal femoral anatomic axes (AMA) are measured as reference angles of resection of distal femur, and the entry points of intramedullary femoral guide are also planned. The purpose of this study is to investigate the influence of femoral position on radiographic planning in TKA. Materials and Methods. We examined 20 knees of 20 female patients who received TKA. Fourteen patients suffered from primary osteoarthritis of the knees, and 6 suffered from rheumatoid arthritis. Fifteen patients have varus knee deformities and 5 patients have valgus knee deformities. Long leg computed topography scans were performed in all cases before operations, and all images were stored in DICOM file format. The analyses were performed with computer software (3D template, JMM, Osaka, Japan) using DICOM formatted data. The planes containing the center of femoral head and transepicondylar axes were defined as reference planes, and the reference planes were fixed all through analyses. At first, to assess the influence of femoral rotation, the femur was rotated from 30 degrees external rotation to 30 degrees internal rotation in 5 degrees increments in full extension. After that, to examine the influence of knee flexion, the knee was bended from full extension to 30 degrees flexion in 5 degrees increments in neutral rotation. Reconstructed coronal planes parallel to the reference planes were made, the angles between mechanical axes of the femur and distal femoral anatomic axes (AMA) and the distance from entry points to the center of femoral intercondylar notch were measured in each position. The distal anatomic axes were made by connecting the center of femoral canal at 8 centimeters proximal to joint line and that at 16 centimeters proximal to joint line. The entry points of intramedullary femoral guide were defined the points where distal anatomic axes meets intercondylar notch. Results. The mean AMA was 6.8 degrees in neutral position, 7.1 degrees in 10 degrees external rotation, 7.3 in 20 degrees external rotation, 7.2 in 30 degrees external rotation, 6.2 in 10 degrees internal rotation, 5.5 in 20 degrees internal rotation, 4.6 in 30 degrees internal rotation, 6.9 in 10 degrees flexion, 7.2 in 20 degrees flexion, 7.8 in 30 degrees flexion, respectively. The entry points moved 3.9 millimeters laterally in 20 degrees external rotation and 3.6 millimeters medially in 20 degrees internal rotation relative to neutral position. Discussion and Conclusion. Femoral position affected on preoperative planning using anteroposterior radiographs. It is important to get a correct anteroposerior view of total femur, because the femur was easy to rotate in knee disorders

Introduction: The infrapatellar fat pad was first described in 1904 by Albert Hoffa. Sometimes disregarded, it is apparent that the infrapatellar fat pad is of importance to knee joint function as fat at this site is only lost in severely emaciated individuals. Also, recent MRI studies have described various pathological changes affecting the fat pad. This study examined the anatomy of the infrapatellar fat pad in relation to knee symptoms and surgical approaches. Materials and Methods: 8 preserved knees were dissected via semicircular parapatellar incisions extending from the tibial tubercle to the superior patellar border and including the quadriceps muscle 13 cm above the superior border of the patella. The synovial membrane of the joint and the ligamentum mucosum were divided and the tibial tubercle was then excised. The resultant tissue complex was removed and the fat pad dissected away from surrounding structures. The appearance, volume and presence of any clefts in the pad were recorded. The cadaveric dissections were then compared to direct observation of the fat pad during total knee replacement, during arthroscopy and on MR imaging. Results: The infrapatellar fat pad was found to be present in all cases. It had a consistent shape consisting of a central mass with medial and lateral extensions. The ligamentum mucosum was attached to the intercondylar notch of the femur in all cases and measured an average of 15.7mm at its base. A horizontal cleft was found in 6 cases and a vertical cleft was found in 7 cases. Both have been previously noted. A tag extended superiorly from the posterior aspect of the fat pad in 7 cases. The volume of the fat pad had quite a large range among individual cadavers (average volume was 24 ml, range: 12–36ml). The intra-individual variation was smaller with an average difference of 4ml (range:2.7ml) between knees. Discussion: The infrapatellar fat pad has been implicated in a wide variety of conditions affecting the knee joint. It has been shown to be involved in arthofibrosis of the knee following surgery, patellar tendonitis, formation of intra-articular fibrous bands, and a site of an ossifying chondroma. It seems that fat pad pathology is usually secondary to other knee joint pathology and primary involvement is rare. The presence of clefts in the fat pad is of importance as a distended cleft may mimic an abnormality and an abnormality in the cleft may be overlooked on imaging of the knee joint. The appearance of the fat pad on direct visualisation in the living person presented a fat pad with a more globular appearance than that seen in the cadaver. The clefts were clearly visualised on MRI. Conclusion: The infrapatellar fat pad is a structure that is consistently present in the knee joint. It consists of a central body with medial and lateral and medical extensions. It usually contains a vertical cleft located superiorly and a horizontal cleft located inferiorly as well as a tag of fat extending superiorly, which forms the roof of the vertical cleft. The infrapatellar fat pad is attached to the intercondylar notch of the femur by the ligamentum mucosum and is firmly anchored to the patella by dense fibrous tissue

Purpose. Leg length discrepancy after total hip arthroplasty (THA) sometimes causes significant patient dissatisfaction. In consideration of the leg length after THA, leg length discrepancy is often measured using anteroposterior (AP) pelvic radiography. However, some cases have discrepancies in femoral and tibial lengths, and we believe that in some cases, true leg length differences should be taken into consideration in total leg length measurement. We report the lengths of the lower limb, femur, and tibia measured using the preoperative standing AP full-leg radiographs of the patients who underwent THA. Materials and methods. From August 2013 to February 2017, 282 patients underwent standing AP full-leg radiography before THA. Of the patients, 33 were male and 249 were female. The mean age of the patients was 65.7±9.4 years. We measured the distances between the center of the tibial plafond and lesser trochanter apex (A-L), between the femoral intercondylar notch and lesser trochanter (K-L), and between the centers of the tibial plafond and intercondylar spine of the tibia (A-K) on standing AP full-leg radiographs before THA operation. We examined the differences in leg length and the causes of these discrepancies after guiding the difference between them. Results. The mean A-L was 674±44 mm on the right and 677±43 mm on the left. The mean difference between the left and the right was 6.2±7 mm. The differences of ≥5 and ≥10 mm between the left and right were confirmed in 131 (46%) and 39 cases (14%), respectively. The mean K-L was 343±23 mm on the right and 343±23 mm on the left, with a mean difference of 4.4±4 mm. The lateral differences of ≥5 and ≥10 mm were confirmed in 88 (31%) and 22 (8%), respectively. The mean A-K was 325±22 mm on the right and 327±22 mm on the left, with a mean difference of 4±4.5 mm. The differences of ≥5 and ≥10 mm between the left and right were confirmed in 24 (9%) and 67 cases (%), respectively. Discussion. Considering the total length of the lower limbs beyond the little trochanter and the leg length after THA, we confirmed that 46% of the leg length differences of ≥5 mm were admitted to 14%. Thus, THA appeared effective. Perthes head, Crowe classifications 3 and 4, history of childhood paralysis, and so on may be factors for leg length differences beyond the lesser trochanter. Conclusion. We think that it would be preferable to prepare a preoperative plan to measure leg length after THA by measuring the total length of the lower extremity before surgery and determining the difference between the left and right sides

In performing posterior cruciate ligament- retaining total knee arthroplasty (CR-TKA), the original surgical instrument was devised to obtain the range of motion and stability of the knee joint adequate for daily life of Japanese people. We have presumed the tentative joint line as intercondylar notch point of the distal femur, and performed surgery using surface replacement to resect metal width of the femoral component for the distal femur by setting the knee to the original position based on understanding of the shape of anterior curvature of the distal femur in Japanese people in case of implanting the femoral component. In order to obtain stability of the knee, we have minimally released the soft tissue and resected the anterior cruciate ligament (ACL), whereas completely preserved the posterior cruciate ligament (PCL) and maintained physiological ligament balance of the knee joint by resecting the medial condyle of the tibia (genu varus). Our surgical procedure enabled deep flexion knee (knee embracing) greater than 145 degrees in 9.7% and also allowed Japanese sitting in three different designs of total knee joints

Posterior stabilized (PS) total knee arthroplasty (TKA), wherein mechanical engagement of the femoral cam and tibial post prevents abnormal anterior sliding of the knee, is a proven surgical technique. However, many patients complain about abnormal clicking sensation, and several reports of severe wear and catastrophic failure of the tibial post have been published. In addition to posterior cam-post engagement during flexion, anterior engagement with femoral intercondylar notch can also occur during extension. The goal of this study was to use dynamic simulations to explore sensitivity of tibial post loading to implant design and alignment, across different activities. LifeModeler KneeSIM software was used to calculate tibial post contact forces for four contemporary PS implants (Triathlon PS, Stryker; Journey BCS and Legion PS, Smith & Nephew; LPS Flex, Zimmer Biomet). An average model of the knee, including cartilage and soft tissue insertion locations, created from MRI data of 40 knees was used to mount and align the component. The Triathlon femoral component was mounted with posterior and distal condylar tangency at: a) both medial and lateral condylar cartilage (anatomic alignment), b) at the medial condylar cartilage and perpendicular to mechanical axis (mechanical alignment with medial tangency), and c) at lateral condylar cartilage and perpendicular to mechanical axis (mechanical alignment with lateral tangency). The influence of implant design was assessed via simulations for the other implant systems with the femoral components aligned perpendicular to mechanical axis with lateral tangency. Five different activities were simulated. The anterior contact force was significantly smaller than the posterior contact force, but it varied noticeably with tibial insert slope and implant design. For Triathlon PS, during most activities anatomic alignment of the femoral component resulted in greater anterior contact force compared to mechanical alignment, but absolute magnitude of forces remained small (<100N). Mechanical alignment with medial tangency resulted in greater posterior contact force for deep knee bend and greater anterior force for chair sit activity. For all implants, peak posterior contact forces were greater for activities with greater peak knee flexion. The magnitude of posterior contact forces for the various implants was comparable to other reports in literature. Overall activity type, implant design and slope had greater impact on post loading than alignment method. Tibial insert slope was shown to be important for anterior post loading, but not for posterior post loading. Anatomic alignment could increase post loading with contemporary TKA systems. In the case of the specific design for which effect of alignment was evaluated, the changes in force magnitude with alignment were modest (<200N). Nonetheless, results of this study highlight the importance of evaluating the effect of different alignment approaches on tibial post loading

Introduction. Current techniques in total knee arthroplasty aim to restore the coronal mechanical axis to neutral. Preoperative planning has historically been based on long-leg standing films (LLSF) which allow surgeons to plan bony resection and soft tissue releases. However, LSSF can be prone to error if malrotated. Recently, patient-specific guides (PSG) utilizing supine magnetic resonance imaging (sMRI) have become an accepted technique for preoperative planning. In this study we sought to compare the degree of coronal deformity using LLSF and sMRI. Methods. Two hundred thirty knees underwent planning for total knee arthroplasty with sMRI and LLSF. Coronal plane deformity was determined based on the femoral-tibial angle (FTA) as defined by the angle formed between a line from the center of the femoral head to the intercondylar notch and a line from the middle of the tibial spines to the middle of the ankle joint. Mechanical axis values from the sMRI were compared with values obtained from LLSF. Results. There were 172 varus knees and 58 valgus knees. There was significant correlation (r=0.9215) between LLSF and sMRI for the measurement of coronal plane deformity for all knees. sMRI underestimated the severity of deformity by 2.19 degrees of varus (p<0.001). Additionally, as the severity of the deformity increased, there was also an increase in the discrepancy between sMRI and LLSF. There was a smaller discrepancy for valgus knees (−0.66 degrees) than varus knees (3.15 degrees, p<0.001). The discrepancy between the two modalities was not affected by gender (p=0.386). Conclusion. sMRI based imaging can help approximate coronal plane deformity in the preoperative planning of TKA but it has limitations. This MRI-based technique tended to underestimate deformity in varus knees and patients with extreme deformity. Surgeons may use sMRI for pre-operative planning but must understand that they tend to underestimate the severity of deformity

Background:. The Lateral Intercondylar Ridge (LIR) gained notoriety with arthroscopic trans-tibial Anterior Cruciate Ligament (ACL) reconstruction where it was mistakenly used to position the ‘over the top’ guide resulting in graft malposition. With anatomic ACL reconstruction some surgeons use the same ridge to define the anterior margin of the ACL femoral insertion in order to guide graft placement. However there is debate about whether this ridge is a consistent and reliable anatomical structure. The aim of our study was to identify whether the LIR is a consistent anatomical structure and to define its relationship with the femoral ACL insertion. Methods:. In the first part, we studied 23 dry bone specimens. Using a digital microscribe, we created a 3D model of the medial surface of the lateral femoral condyle to evaluate whether there was an identifiable bony ridge. In the second part, we studied 7 cadaveric specimens with soft tissues intact. The soft tissues were dissected to identify the femoral ACL insertion. A 3D reconstruction of the femoral insertion and the surface allowed us to define the relationship between the LIR and the ACL insertion. Results:. All specimens (23 dry bones; 7 intact soft tissues) had a defined ridge on the medial surface of the lateral femoral condyle. The ridge extends from the apex point of the lateral intercondylar notch, where the posterior condyle meets the femoral shaft, and extends obliquely to the articular margin. The mean distance from the midpoint of the posterior condylar articular margin was 10.1 mm. The ridge was consistently located just anterior to the femoral ACL insertion. Conclusion:. This study shows that the LIR is a consistent anatomical structure that defines the anterior margin of the femoral ACL insertion. This supports its use as a landmark for femoral tunnel placement in ACL reconstruction surgery. Abstract 28