scholarly journals Unicompartmental Knee Resurfacing: Enlarged Tibio-Femoral Contact Area and Reduced Contact Stress Using Novel Patient-Derived Geometries

2010 ◽  
Vol 4 (1) ◽  
pp. 85-92 ◽  
Author(s):  
Nick Steklov ◽  
John Slamin ◽  
Sudesh Srivastav ◽  
Darryl D’Lima
Keyword(s):  
Contact Stress ◽  
Contact Area ◽  
Polyethylene Wear ◽  
Femoral Condyle ◽  
Implant Design ◽  
Heel Strike ◽  
Patient Specific ◽  
Computer Assisted ◽  
Average Curvature ◽  
Standard Deviations

Advances in imaging technology and computer-assisted design (CAD) have recently enabled the introduction of patient-specific knee implant designs that hold the potential to improve functional performance on the basis of patient-specific geometries, namely a patient-specific sagittal and coronal curvature, as well as enhanced bone preservation. The objective of this study was to investigate the use of a novel implant design utilizing a patient specific sagittal J-curve on the femoral component combined with a novel constant, patient-derived femoral coronal curvature and to assess tibio-femoral contact area and contact stress on a femur matched curved tibial polyethylene insert. Mean contact area and standard deviations were 81±5, 96±5 and 74±4 mm2 for the heel strike, toe off and mid-stance positions, respectively. Mean contact stress and standard deviations were 23.83±1.39, 23.27±1.14 and 20.78±0.54 MPa for the heel strike, toe off and mid-stance positions, respectively. Standard deviations of the measurements were small, not exceeding 6-7% confirming the consistency of loading conditions across different flexion angles. The results were comparable to those reported for standard, off-the-shelf fixed-bearing implants with paired femoral and tibial geometries. These data show that a constant coronal curvature can be applied to a patient-specific implant by measuring coronal curvatures across the femoral condyle in each patient and by deriving an average curvature. This novel approach combines unique benefits of patient-specific geometry with proven design concepts for minimizing polyethylene wear.

Load-Bearing at the Meniscofemoral Joint: An in vitro Study in the Canine Knee

2011 ◽  
Vol 1 (1) ◽  
pp. 39-43 ◽  
Author(s):  
Pier Francesco Indelli ◽  
John A Szivek ◽  
Andrew Schnepp ◽  
William A Grana
Keyword(s):  
Contact Stress ◽  
Contact Area ◽  
Knee Flexion ◽  
Femoral Condyle ◽  
Testing Machine ◽  
Partial Meniscectomy ◽  
Clinical Value ◽  
Contact Areas ◽  
Local Contact ◽  
Femoral Condyles

ABSTRACT Background The role of the menisci on tibial load transmission and stress distribution has been extensively studied, but few studies have focused on the meniscofemoral joint during physiologic weightbearing. The objective of this study was to determine the contact areas and local contact stresses at the meniscofemoral interface during physiologic range of motion and axial-loading in the canine knee and to determine the influence of a partial or total meniscectomy. Methods Both fresh-frozen knees of 3 hound-type canines were tested in a universal testing machine configured for an axial-load of 90-120 N. Measurement of the contact area and the local contact stress were done at three different knee angles (30; 50; 70) and with both menisci intact, after partial meniscectomy, and after total meniscectomy. Pressure distribution was estimated by using pressure sensitive film inserted above the menisci. Results After partial meniscectomy, contact areas at 50° of knee flexion decreased approximately 25% on both femoral condyles, and local contact stress increased 30% on the medial femoral condyle but remained unchanged on the lateral. After total meniscectomy, contact areas at 50° of knee flexion decreased approximately 75% on both femoral condyles, and local contact stress increased approximately 60% on the medial compartment and 100% on the lateral compartment. Conclusions These data suggest that a conservative partial meniscectomy leaves the meniscus with an inferior weight distribution function; decreasing, but not canceling the protection on the femoral hyaline cartilage. A dramatic decrease of contact area followed by an increase of local contact stress was noted after a total meniscectomy. The clinical value of this study is to emphasize the biomechanical value of surgical procedures addressing the repair of damaged menisci.

scholarly journals Polyethylene Wear is Related to Patient-specific Contact Stress in THA

2011 ◽  
Vol 469 (12) ◽  
pp. 3415-3422 ◽  
Author(s):  
Robert Košak ◽  
Veronika Kralj-Iglič ◽  
Aleš Iglič ◽  
Matej Daniel
Keyword(s):  
Contact Stress ◽  
Polyethylene Wear ◽  
Patient Specific ◽  
Specific Contact

scholarly journals Post Operative Analysis of a Novel Application of Surgical Navigation

10.29007/qmm6 ◽  
2020 ◽  
Author(s):  
Benjamin Roberts ◽  
Willy Theodore
Keyword(s):  
Surgical Navigation ◽  
Sagittal Alignment ◽  
Low Cost ◽  
Femoral Condyle ◽  
Computer Assisted Surgery ◽  
Patient Specific ◽  
Computer Assisted ◽  
Tibial Resection ◽  
Patient Specific Instrumentation ◽  
The Mean

A cohort of 84 patients underwent Total Knee Replacement surgery using Patient Specific Instrumentation fitted with an optical tracker that was monitored by a Computer Assisted Surgery system. The CAS system was low cost with small footprint in the operating theatre. The hip centre was collected and four other landmarks were recorded as rotational measures. The CAS system then reported the deviation in PSI placement against the targeted PSI placement, the surgeon then made a judgement whether to replace the guide. Post-operative analysis was done to determine the achieved alignment of the component and compared to the targeted alignment. From 45 results available for analysis the study found that the mean of rotational measures over the femur and tibia were found to be within ±30 of the targeted alignment, except for femur sagittal alignment. When a single outlier was removed from the femur sagittal alignment measures, the mean fell below ±30 of the targeted alignment. Distal femoral condyle resection measures fell below a mean of 1mm and posterior femoral condyle measures fell below a mean of 2mm. Lateral proximal tibial resection fell below a mean of 2.5mm as did medial proximal tibial resection when two outliers were removed. This shows that a CAS system incorporating the low cost, quicker time, and smaller footprint benefits of PSI with the accuracy of traditional navigation may be a feasible device.

Complex Pelvic Reconstruction using Patient-Specific Instrumentation and a 3D-Printed Custom Implant following Tumor Resection

2018 ◽  
Vol 02 (02) ◽  
pp. 061-067 ◽  
Author(s):  
David Hennessy ◽  
Megan Anderson ◽  
Santiago Lozano-Calderón
Keyword(s):  
Proximal Femur ◽  
Tumor Resection ◽  
Computer Assisted Surgery ◽  
Implant Design ◽  
Patient Specific ◽  
Computer Assisted ◽  
Limb Salvage Surgery ◽  
Assisted Navigation ◽  
Patient Specific Instrumentation ◽  
Custom Implant

AbstractResection of a periacetabular sarcoma is a difficult surgical problem due to the complex bony and soft tissue anatomy. The challenge of pelvic tumor resection lies in achieving clear margins while also reconstructing the defect with a durable construct. Limb salvage surgery involving these types of tumors, as well as other tumors of the pelvis, has made great progress recently due to remarkable technological innovation in the field of computer-assisted surgery and custom implant design. In this study, the authors review the case of a 9-year-old child with an osteosarcoma arising from the proximal femur with local spread into the hip joint and a skip metastasis in the ipsilateral acetabulum. They undertook limb-sparing extra-articular resection of the sarcoma with a reconstruction consisting of a 3D-custom printed pelvic implant and a proximal femur extendible prosthesis. The resection of the pelvis was performed with patient-specific cutting guides, rather than computer-assisted navigation. The resection resulted in a clear margin and the patient has had no evidence of local recurrence. These patient-specific guides closely matched the planned resection in terms of orientation in the pelvis, which allowed for straightforward implantation of the custom prosthesis at the time of surgery. The result has been a durable reconstruction that has produced an excellent functional outcome for this patient.

Patient-Specific Contact Stress Does Not Predict Polyethylene Wear Rate in a Specific Pressfit Cup

2017 ◽  
Vol 32 (12) ◽  
pp. 3802-3805 ◽  
Author(s):  
Georg Matziolis ◽  
Linda Krakow ◽  
Frank Layher ◽  
Klaus Sander ◽  
Joerg Bossert ◽  
...  
Keyword(s):  
Wear Rate ◽  
Contact Stress ◽  
Polyethylene Wear ◽  
Patient Specific ◽  
Specific Contact

Cervical 1-2 Posterior Instrumented Fusion Utilizing Computer-Assisted Navigation With Harvest of Rib Strut Autograft: 2-Dimensional Operative Video

2021 ◽  
Author(s):  
Timothy J Yee ◽  
Michael J Strong ◽  
Matthew S Willsey ◽  
Mark E Oppenlander
Keyword(s):  
Surface Area ◽  
Odontoid Process ◽  
Odontoid Fracture ◽  
Patient Specific ◽  
Computer Assisted ◽  
Type Ii ◽  
Instrumented Fusion ◽  
Assisted Navigation ◽  
Patient Consent ◽  
Posterior Instrumented Fusion

Abstract Nonunion of a type II odontoid fracture after the placement of an anterior odontoid screw can occur despite careful patient selection. Countervailing factors to successful fusion include the vascular watershed zone between the odontoid process and body of C2 as well as the relatively low surface area available for fusion. Patient-specific factors include osteoporosis, advanced age, and poor fracture fragment apposition. Cervical 1-2 posterior instrumented fusion is indicated for symptomatic nonunion. The technique leverages the larger posterolateral surface area for fusion and does not rely on bony growth in a watershed zone. Although loss of up to half of cervical rotation is expected after C1-2 arthrodesis, this may be better tolerated in the elderly, who may have lower physical demands than younger patients. In this video, we discuss the case of a 75-yr-old woman presenting with intractable mechanical cervicalgia 7 mo after sustaining a type II odontoid fracture and undergoing anterior odontoid screw placement at an outside institution. Cervical radiography and computed tomography exhibited haloing around the screw and nonunion across the fracture. We demonstrate C1-2 posterior instrumented fusion with Goel-Harms technique (C1 lateral mass and C2 pedicle screws), utilizing computer-assisted navigation, and modified Sonntag technique with rib strut autograft.  Posterior C1-2-instrumented fusion with rib strut autograft is an essential technique in the spine surgeon's armamentarium for the management of C1-2 instability, which can be a sequela of type II dens fracture. Detailed video demonstration has not been published to date.  Appropriate patient consent was obtained.

scholarly journals Total Meniscus Reconstruction Using a Polymeric Hybrid-Scaffold: Combined with 3D-Printed Biomimetic Framework and Micro-Particle

Polymers ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 1910
Author(s):  
Hun-Jin Jeong ◽  
Se-Won Lee ◽  
Myoung Wha Hong ◽  
Young Yul Kim ◽  
Kyoung Duck Seo ◽  
...  
Keyword(s):  
Shape Matching ◽  
Femoral Condyle ◽  
Immunohistochemical Analysis ◽  
Cartilage Degeneration ◽  
Patient Specific ◽  
Hybrid Scaffold ◽  
Meniscus Tissue ◽  
Cell Source ◽  
3D Printed ◽  
Meniscus Regeneration

The meniscus has poor intrinsic regenerative capability, and its injury inevitably leads to articular cartilage degeneration. Although there are commercialized off-the-shelf alternatives to achieve total meniscus regeneration, each has its own shortcomings such as individualized size matching issues and inappropriate mechanical properties. We manufactured a polycaprolactone-based patient-specific designed framework via a Computed Tomography scan images and 3D-printing technique. Then, we completed the hybrid-scaffold by combining the 3D-printed framework and mixture micro-size composite which consists of polycaprolactone and sodium chloride to create a cell-friendly microenvironment. Based on this hybrid-scaffold with an autograft cell source (fibrochondrocyte), we assessed mechanical and histological results using the rabbit total meniscectomy model. At postoperative 12-week, hybrid-scaffold achieved neo-meniscus tissue formation, and its shape was maintained without rupture or break away from the knee joint. Histological and immunohistochemical analysis results showed obvious ingrowth of the fibroblast-like cells and chondrocyte cells as well as mature lacunae that were embedded in the extracellular matrix. Hybrid-scaffolding resulted in superior shape matching as compared to original meniscus tissue. Histological analysis showed evidence of extensive neo-meniscus cell ingrowth. Additionally, the hybrid-scaffold did not induce osteoarthritis on the femoral condyle surface. The 3D-printed hybrid-scaffold may provide a promising approach that can be applied to those who received total meniscal resection, using patient-specific design and autogenous cell source.

Thermomechanical Coupling of a Hyper-viscoelastic Truck Tire and a Pavement Layer and its Impact on Three-dimensional Contact Stresses

2021 ◽  
pp. 036119812110171
Author(s):  
Angeli Jayme ◽  
Imad L. Al-Qadi
Keyword(s):  
Contact Stress ◽  
Contact Area ◽  
Three Dimensional ◽  
Interaction Model ◽  
Rolling Resistance ◽  
Contact Stresses ◽  
Thermomechanical Coupling ◽  
Temperature Profiles ◽  
Near Surface ◽  
Truck Tire

A thermomechanical coupling between a hyper-viscoelastic tire and a representative pavement layer was conducted to assess the effect of various temperature profiles on the mechanical behavior of a rolling truck tire. The two deformable bodies, namely the tire and pavement layer, were subjected to steady-state-uniform and non-uniform temperature profiles to identify the significance of considering temperature as a variable in contact-stress prediction. A myriad of ambient, internal air, and pavement-surface conditions were simulated, along with combinations of applied tire load, tire-inflation pressure, and traveling speed. Analogous to winter, the low temperature profiles induced a smaller tire-pavement contact area that resulted in stress localization. On the other hand, under high temperature conditions during the summer, higher tire deformation resulted in lower contact-stress magnitudes owing to an increase in the tire-pavement contact area. In both conditions, vertical and longitudinal contact stresses are impacted, while transverse contact stresses are relatively less affected. This behavior, however, may change under a non-free-rolling condition, such as braking, accelerating, and cornering. By incorporating temperature into the tire-pavement interaction model, changes in the magnitude and distribution of the three-dimensional contact stresses were manifested. This would have a direct implication on the rolling resistance and near-surface behavior of flexible pavements.

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