Synthetic PVA Osteochondral Implants for the Knee Joint: Mechanical Characteristics During Simulated Gait

Background: Although polyvinyl alcohol (PVA) implants have been developed and used for the treatment of femoral osteochondral defects, their effect on joint contact mechanics during gait has not been assessed. Purpose/Hypothesis: The purpose was to quantify the contact mechanics during simulated gait of focal osteochondral femoral defects and synthetic PVA implants (10% and 20% by volume of PVA), with and without porous titanium (pTi) bases. It was hypothesized that PVA implants with a higher polymer content (and thus a higher modulus) combined with a pTi base would significantly improve defect-related knee joint contact mechanics. Study Design: Controlled laboratory study. Methods: Four cylindrical implants were manufactured: 10% PVA, 20% PVA, and 10% and 20% PVA disks mounted on a pTi base. Devices were implanted into 8 mm–diameter osteochondral defects created on the medial femoral condyles of 7 human cadaveric knees. Knees underwent simulated gait and contact stresses across the tibial plateau were recorded. Contact area, peak contact stress, the sum of stress in 3 regions of interest across the tibial plateau, and the distribution of stresses, as quantified by tracking the weighted center of contact stress throughout gait, were computed for all conditions. Results: An osteochondral defect caused a redistribution of contact stress across the plateau during simulated gait. Solid PVA implants did not improve contact mechanics, while the addition of a porous metal base led to significantly improved joint contact mechanics. Implants consisting of a 20% PVA disk mounted on a pTi base significantly improved the majority of contact mechanics parameters relative to the empty defect condition. Conclusion: The information obtained using our cadaveric test system demonstrated the mechanical consequences of femoral focal osteochondral defects and provides biomechanical support to further pursue the efficacy of high-polymer-content PVA disks attached to a pTi base to improve contact mechanics. Clinical Relevance: As a range of solutions are explored for the treatment of osteochondral defects, our preclinical cadaveric testing model provides unique biomechanical evidence for the continued investigation of novel solutions for osteochondral defects.

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Lateral Meniscal Graft Transplantation: Effect of Fixation Method on Joint Contact Mechanics During Simulated Gait

The American Journal of Sports Medicine ◽

10.1177/0363546519860113 ◽

2019 ◽

Vol 47 (10) ◽

pp. 2437-2443 ◽

Cited By ~ 3

Author(s):

Caroline Brial ◽

Moira McCarthy ◽

Olufunmilayo Adebayo ◽

Hongsheng Wang ◽

Tony Chen ◽

...

Keyword(s):

Knee Joint ◽

Contact Mechanics ◽

Contact Stress ◽

Contact Area ◽

Gait Cycle ◽

Fixation Techniques ◽

Joint Contact ◽

Bone Plug ◽

Bony Fixation ◽

Intact Knee

Background: Controversy exists regarding the optimal bony fixation technique for lateral meniscal allografts. Purpose/Hypothesis: The objective was to quantify knee joint contact mechanics across the lateral plateau for keyhole and bone plug meniscal allograft transplant fixation techniques throughout simulated gait. It was hypothesized that both methods of fixation would improve contact mechanics relative to the meniscectomized condition, while keyhole fixation would restore the distribution of contact stress closer to that of the intact knee. Study Design: Controlled laboratory study. Methods: Six human cadaveric knees were mounted on a multidirectional dynamic simulator and subjected to the following conditions: (1) native intact meniscus, (2) keyhole fixation of the native meniscus, (3) bone plug fixation of the native meniscus, and (4) meniscectomy. Contact area, peak contact stress, and the distribution of stress across the tibial plateau were computed at 14% and 45% of the gait cycle, at which axial forces are at their highest. Translation of the weighted center of contact stress throughout simulated gait was computed. Results: Both bony fixation techniques improved contact mechanics relative to the meniscectomized condition. The keyhole technique was not significantly different from the intact condition for the following metrics: contact area, peak contact stress, distribution of force between the meniscal footprint and cartilage-to-cartilage contact, and the position of the weighted center of contact. In contrast, bone plug fixation resulted in a significant decrease of 21% to 28% in contact area at 14% and 45% of the simulated gait cycle, a significant increase in peak contact stresses of 34% at 45% of the gait cycle, and a shift in the weighted center of contact, which increased forces in the cartilage-to-cartilage contact area at 45% of the gait cycle. Conclusion: While both keyhole and bone plug fixation methods improved lateral compartment contact mechanics relative to the meniscectomized knee, keyhole fixation restored contact mechanics closer to that of the intact knee. Clinical Relevance: Method of meniscal fixation is under the direct control of the surgeon. From a biomechanics perspective, keyhole fixation is advocated for its ability to mimic intact knee joint contact mechanics.

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Lateral Extra-articular Tenodesis Alters Lateral Compartment Contact Mechanics under Simulated Pivoting Maneuvers: An In Vitro Study

The American Journal of Sports Medicine ◽

10.1177/03635465211028255 ◽

2021 ◽

pp. 036354652110282

Author(s):

Niv Marom ◽

Hamidreza Jahandar ◽

Thomas J. Fraychineaud ◽

Zaid A. Zayyad ◽

Hervé Ouanezar ◽

...

Keyword(s):

Contact Mechanics ◽

Contact Force ◽

Contact Stress ◽

Tibial Plateau ◽

Cruciate Ligament ◽

In Vitro Study ◽

Lateral Compartment ◽

Lateral Tibial Plateau ◽

Intact Knee

Background: There is concern that utilization of lateral extra-articular tenodesis (LET) in conjunction with anterior cruciate ligament (ACL) reconstruction (ACLR) may disturb lateral compartment contact mechanics and contribute to joint degeneration. Hypothesis: ACLR augmented with LET will alter lateral compartment contact mechanics in response to simulated pivoting maneuvers. Study Design: Controlled laboratory study. Methods: Loads simulating a pivot shift were applied to 7 cadaveric knees (4 male; mean age, 39 ± 12 years; range, 28-54 years) using a robotic manipulator. Each knee was tested with the ACL intact, sectioned, reconstructed (via patellar tendon autograft), and, finally, after augmenting ACLR with LET (using a modified Lemaire technique) in the presence of a sectioned anterolateral ligament and Kaplan fibers. Lateral compartment contact mechanics were measured using a contact stress transducer. Outcome measures were anteroposterior location of the center of contact stress (CCS), contact force from anterior to posterior, and peak and mean contact stress. Results: On average, augmenting ACLR with LET shifted the lateral compartment CCS anteriorly compared with the intact knee and compared with ACLR in isolation by a maximum of 5.4 ± 2.3 mm ( P < .001) and 6.0 ± 2.6 mm ( P < .001), respectively. ACLR augmented with LET also increased contact force anteriorly on the lateral tibial plateau compared with the intact knee and compared with isolated ACLR by a maximum of 12 ± 6 N ( P = .001) and 17 ± 10 N ( P = .002), respectively. Compared with ACLR in isolation, ACLR augmented with LET increased peak and mean lateral compartment contact stress by 0.7 ± 0.5 MPa ( P = .005) and by 0.17 ± 0.12 ( P = .006), respectively, at 15° of flexion. Conclusion: Under simulated pivoting loads, adding LET to ACLR anteriorized the CCS on the lateral tibial plateau, thereby increasing contact force anteriorly. Compared with ACLR in isolation, ACLR augmented with LET increased peak and mean lateral compartment contact stress at 15° of flexion. Clinical Relevance: The clinical and biological effect of increased anterior loading of the lateral compartment after LET merits further investigation. The ability of LET to anteriorize contact stress on the lateral compartment may be useful in knees with passive anterior subluxation of the lateral tibia.

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The Effect of the Tibiofemoral Contact Path Centroid Location on TKR Contact Forces

ASME 2010 Summer Bioengineering Conference, Parts A and B ◽

10.1115/sbc2010-19407 ◽

2010 ◽

Cited By ~ 1

Author(s):

Hannah J. Lundberg ◽

Markus A. Wimmer

Keyword(s):

Knee Joint ◽

Tibial Plateau ◽

Soft Tissues ◽

Three Dimensional ◽

Solution Space ◽

Contact Forces ◽

Detailed Knowledge ◽

Joint Contact ◽

Total Knee

Detailed knowledge of in vivo knee contact forces and the contribution from muscles, ligaments, and other soft-tissues to knee joint function are essential for evaluating total knee replacement (TKR) designs. We have recently developed a mathematical model for calculating knee joint contact forces using parametric methodology (Lundberg et al., 2009). The numerical model calculates a “solution space” of three-dimensional contact forces for both the medial and lateral compartments of the tibial plateau. The solution spaces are physiologically meaningful, and represent the result of balancing the external moments and forces by different strategies.

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Knee joint contact mechanics during downhill gait and its relationship with varus/valgus motion and muscle strength in patients with knee osteoarthritis

The Knee ◽

10.1016/j.knee.2015.07.011 ◽

2016 ◽

Vol 23 (1) ◽

pp. 49-56 ◽

Cited By ~ 15

Author(s):

Shawn Farrokhi ◽

Carrie A. Voycheck ◽

Jonathan A. Gustafson ◽

G. Kelley Fitzgerald ◽

Scott Tashman

Keyword(s):

Muscle Strength ◽

Knee Joint ◽

Knee Osteoarthritis ◽

Contact Mechanics ◽

Joint Contact

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Joint contact stress improves in dysplastic hips after periacetabular osteotomy but remains higher than in normal hips

Hip International ◽

10.1177/11207000211036414 ◽

2021 ◽

pp. 112070002110364

Author(s):

Jessica E Goetz ◽

Holly D Thomas-Aitken ◽

Sean E Sitton ◽

Robert W Westermann ◽

Michael C Willey

Keyword(s):

Contact Mechanics ◽

Contact Stress ◽

Stance Phase ◽

Periacetabular Osteotomy ◽

Contact Stresses ◽

Surgical Correction ◽

Element Analysis ◽

Walking Gait ◽

Radiographic Measurements ◽

Joint Contact

Aim: The purpose of this study was to use computational modeling to determine if surgical correction of hip dysplasia restores hip contact mechanics to those of asymptomatic, radiographically normal hips. Methods: Discrete element analysis (DEA) was used to compute joint contact stresses during the stance phase of normal walking gait for 10 individuals with radiographically normal, asymptomatic hips and 10 age- and weight-matched patients with acetabular dysplasia who underwent periacetabular osteotomy (PAO). Results: Mean and peak contact stresses were higher ( p < 0.001 and p = 0.036, respectively) in the dysplastic hips than in the matched normal hips. PAO normalised standard radiographic measurements and medialised the location of computed contact stress within the joint. Mean contact stress computed in dysplastic hips throughout the stance phase of gait (median 5.5 MPa, [IQR 3.9–6.1 MPa]) did not significantly decrease after PAO (3.7 MPa, [IQR 3.2–4.8]; p = 0.109) and remained significantly ( p < 0.001) elevated compared to radiographically normal hips (2.4 MPa, [IQR 2.2–2.8 MPa]). Peak contact stress demonstrated a similar trend. Joint contact area during the stance phase of gait in the dysplastic hips increased significantly ( p = 0.036) after PAO from 395 mm2 (IQR 378–496 mm2) to 595 mm2 (IQR 474–660 mm2), but remained significantly smaller ( p = 0.001) than that for radiographically normal hips (median 1120 mm2, IQR 853–1444 mm2). Conclusions: While contact mechanics in dysplastic hips more closely resembled those of normal hips after PAO, the elevated contact stresses and smaller contact areas remaining after PAO indicate ongoing mechanical abnormalities should be expected even after radiographically successful surgical correction.

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Knee Joint Line Obliquity Causes Tibiofemoral Subluxation That Alters Contact Areas and Meniscal Loading

The American Journal of Sports Medicine ◽

10.1177/03635465211020478 ◽

2021 ◽

pp. 036354652110204

Author(s):

Dong Wang ◽

Lukas Willinger ◽

Kiron K. Athwal ◽

Andy Williams ◽

Andrew A. Amis

Keyword(s):

Knee Joint ◽

Tibial Plateau ◽

Joint Line ◽

Optical Tracking ◽

Materials Testing ◽

Contact Areas ◽

Joint Line Obliquity ◽

Joint Contact ◽

Tibiofemoral Subluxation ◽

Contact Pressures

Background: Little scientific evidence is available regarding the effect of knee joint line obliquity (JLO) before and after coronal realignment osteotomy. Hypotheses: Higher JLO would lead to abnormal relative position of the femur on the tibia, a shift of the joint contact areas, and elevated joint contact pressures. Study Design: Descriptive laboratory study. Methods: 10 fresh-frozen human cadaveric knees (age, 59 ± 5 years) were axially loaded to 1500 N in a materials testing machine with the joint line tilted 0°, 4°, 8°, and 12° varus (“downhill” medially) and valgus, at 0° and 20° of knee flexion. The mechanical compression axis was aligned to the center of the tibial plateau. Contact pressure and contact area were recorded by pressure sensors inserted between the tibia and femur below the menisci. Changes in relative femoral and tibial position in the coronal plane were obtained by an optical tracking system. Results: Both medial and lateral JLO caused significant tibiofemoral subluxation and pressure distribution changes. Medial (varus) JLO caused the femur to subluxate medially down the coronal slope of the tibial plateau, and vice versa for lateral (valgus) downslopes ( P < .01), giving a 6-mm range of subluxation. The areas of peak pressure moved 12 mm and 8 mm across the medial and lateral condyles, onto the downhill meniscus and the “uphill” tibial spine. Changes in JLO had only small effects on maximum contact pressures. Conclusion: A 4° change of JLO during load bearing caused significant mediolateral tibiofemoral subluxation. The femur slid down the slope of the tibial plateau to abut the tibial eminence and also to rest on the downhill meniscus. This caused large movements of the tibiofemoral contact pressures across each compartment. Clinical Relevance: These results provide important information for understanding the consequences of creating coronal JLO and for clinical practice in terms of osteotomy planning regarding the effect on JLO. This information provides guidance regarding the choice of single- or double-level osteotomy. Excessive JLO alteration may cause abnormal tibiofemoral joint articulation and chondral or meniscal loading.

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A Weighted Objective Function Reduces Estimates of Medial and Lateral Knee Joint Contact Loads During Gait

ASME 2011 Summer Bioengineering Conference, Parts A and B ◽

10.1115/sbc2011-53594 ◽

2011 ◽

Cited By ~ 1

Author(s):

S. C. E. Brandon ◽

D. G. Thelen ◽

K. J. Deluzio

Keyword(s):

Knee Joint ◽

Tibial Plateau ◽

Soft Tissues ◽

Grand Challenge ◽

Contact Loads ◽

Joint Contact ◽

Reaction Forces ◽

Six Degree Of Freedom ◽

Knee Pathology

Accurate prediction of knee joint contact loading during gait is important for understanding knee pathology and development of suitable clinical interventions. While many researchers have modeled the knee contact loads during level walking, these predictions have ranged from 3.4 [1] to 7 [2] times body weight. Validation of contact loads is difficult; the joint contact load depends not only on readily obtainable external kinematics and reaction forces, but also on the forces generated by muscle and other soft tissues. Recently, an instrumented tibial implant, capable of telemetrically reporting the six degree-of-freedom loading environment of the tibial plateau, was used to tune and validate an EMG-driven model of the lower extremity [3]. Recognizing the value of these in vivo data, and the limitations of existing knee models, these researchers devised the Grand Challenge Competitions to Predict In Vivo Knee Loads.

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Changes in Joint Contact Mechanics in a Large Quadrupedal Animal Model After Partial Meniscectomy and a Focal Cartilage Injury

Journal of Biomechanical Engineering ◽

10.1115/1.4036148 ◽

2017 ◽

Vol 139 (5) ◽

Cited By ~ 1

Author(s):

David J. Heckelsmiller ◽

M. James Rudert ◽

Thomas E. Baer ◽

Douglas R. Pedersen ◽

Douglas C. Fredericks ◽

...

Keyword(s):

Contact Mechanics ◽

Contact Stress ◽

Cartilage Defect ◽

Center Of Pressure ◽

Mechanical Damage ◽

Cartilage Defects ◽

Joint Injury ◽

Joint Contact ◽

Post Traumatic

Acute mechanical damage and the resulting joint contact abnormalities are central to the initiation and progression of post-traumatic osteoarthritis (PTOA). Study of PTOA is typically performed in vivo with replicate animals using artificially induced injury features. The goal of this work was to measure changes in a joint contact stress in the knee of a large quadruped after creation of a clinically realistic overload injury and a focal cartilage defect. Whole-joint overload was achieved by excising a 5-mm wedge of the anterior medial meniscus. Focal cartilage defects were created using a custom pneumatic impact gun specifically developed and mechanically characterized for this work. To evaluate the effect of these injuries on joint contact mechanics, Tekscan (Tekscan, Inc., South Boston, MA) measurements were obtained pre-operatively, postmeniscectomy, and postimpact (1.2-J) in a nonrandomized group of axially loaded cadaveric sheep knees. Postmeniscectomy, peak contact stress in the medial compartment is increased by 71% (p = 0.03) and contact area is decreased by 35% (p = 0.001); the center of pressure (CoP) shifted toward the cruciate ligaments in both the medial (p = 0.004) and lateral (p = 0.03) compartments. The creation of a cartilage defect did not significantly change any aspect of contact mechanics measured in the meniscectomized knee. This work characterizes the mechanical environment present in a quadrupedal animal knee joint after two methods to reproducibly induce joint injury features that lead to PTOA.

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Direct Validation of Human Knee-Joint Contact Mechanics Derived From Subject-Specific Finite-Element Models of the Tibiofemoral and Patellofemoral Joints

Journal of Biomechanical Engineering ◽

10.1115/1.4045594 ◽

2020 ◽

Vol 142 (7) ◽

Cited By ~ 2

Author(s):

Wei Gu ◽

Marcus G. Pandy

Keyword(s):

Finite Element ◽

Knee Joint ◽

Contact Mechanics ◽

Contact Pressure ◽

Weight Bearing ◽

Human Knee ◽

Human Knee Joint ◽

Joint Contact ◽

Joint Contact Pressure

Abstract The primary aim of this study was to validate predictions of human knee-joint contact mechanics (specifically, contact pressure, contact area, and contact force) derived from finite-element models of the tibiofemoral and patellofemoral joints against corresponding measurements obtained in vitro during simulated weight-bearing activity. A secondary aim was to perform sensitivity analyses of the model calculations to identify those parameters that most significantly affect model predictions of joint contact pressure, area, and force. Joint pressures in the medial and lateral compartments of the tibiofemoral and patellofemoral joints were measured in vitro during two simulated weight-bearing activities: stair descent and squatting. Model-predicted joint contact pressure distribution maps were consistent with those obtained from experiment. Normalized root-mean-square errors between the measured and calculated contact variables were on the order of 15%. Pearson correlations between the time histories of model-predicted and measured contact variables were generally above 0.8. Mean errors in the calculated center-of-pressure locations were 3.1 mm for the tibiofemoral joint and 2.1 mm for the patellofemoral joint. Model predictions of joint contact mechanics were most sensitive to changes in the material properties and geometry of the meniscus and cartilage, particularly estimates of peak contact pressure. The validated finite element modeling framework offers a useful tool for noninvasive determination of knee-joint contact mechanics during dynamic activity under physiological loading conditions.

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