Cartilage Wear Research Articles

Trans-Posterior Cruciate Ligament All-Inside Root Repair Versus Partial Meniscectomy for Medial Meniscus Posterior Root Tears: Comparison of Semiquantitative and Quantitative MRI Outcomes in Cartilage Degeneration and Osteoarthritic Progression.

ObjectiveTo perform conventional, morphological, and T2 mapping compositional MRI imaging to assess the cartilage degeneration and osteoarthritic progression in patients with medial meniscus posterior root tears (MMPRTs) who underwent trans-posterior cruciate ligament (PCL) all-inside repair or partial meniscectomy.DesignPatients with MMPRTs after trans-PCL all-inside repair (group AR) or partial meniscectomy (group PM) between 2015 and 2018 were retrospectively identified. Preoperative and postoperative conventional MRI were collected to assess medial meniscus extrusion (MME) and the whole-organ magnetic resonance imaging score (WORMS). Postoperative morphological MRI and T2 mapping compositional MRI were collected to evaluate the quantitative cartilage thickness/volume and cartilage composition.ResultsThe final cohort consisted of 21 patients in group AR and 22 patients in group PM, with no differences in demographic data and baseline patient characteristics between the 2 groups. Group AR demonstrated less progression of articular cartilage wear (P < 0.05) and decreased meniscal extrusion (P = 0.008) than group PM at the final follow-up. In addition, group AR demonstrated less extracellular matrix degeneration in the cartilage subregion of the medial compartment (P < 0.05) than group PM with lower T2 relaxation times in the superficial layer of the articular cartilage.ConclusionTrans-PCL all-inside repair of MMPRTs could delay the initial cartilage deterioration and morphological cartilage degeneration compared with partial meniscectomy. However, the amount of residual meniscal extrusion is clinically important, and an improved root repair fixation method should be investigated.

Posterior tibial tubercle measured by the sagittal TT-TG distance correlates with increased risk for patellofemoral chondral lesions.

To evaluate the variation in tibial tubercle sagittal alignment in patients with and without patellofemoral (PF) cartilage wear. This was a single-centre, retrospective review of patients that underwent a cartilage restoration procedure for isolated PF cartilage wear from 2014 to 2020. Patients were matched in a 1:2 ratio for age, sex and BMI to partial meniscectomy patients as controls. The sagittal TT-TG (sTT-TG) distance was measured on preoperative axial T2 magnetic resonance imaging (MRI) and was defined as the distance between a point at the nadir of the trochlear cartilage and the most anterior point of the tibial tubercle. One hundred and forty patients (47 cartilage restoration, 94 meniscectomy) were included. Mean age, BMI, and height for the total cohort were 34.01 ± 8.7, 26.6 ± 6.4, and 173.0 ± 17.7 respectively, with 78 males (55%) and 63 females (45%). There were no significant differences between groups for age, BMI or sex (n.s). The cartilage restoration group (- 2.5mm ± 5.9) was found to have a significantly more posterior (negative) sTT-TG compared to the meniscectomy group (1.72mm ± 6.7) (p < 0.001). Interrater reliability was excellent (ICC = 0.931, p < 0.001). Patients with less than - 3.4mm sTT-TG were 2.74 times more likely to have a cartilage restoration procedure compared to those with greater than - 3.4mm (OR 2.7, 95% CI 1.3-5.85). Patients with < - 10mm posterior translation were 13.7× (CI 1.6-111.1) more likely to have a cartilage restoration procedure. Patients that underwent isolated cartilage restoration procedures had a significantly more posterior tibial tubercle than partial meniscectomy controls based on the sagittal TT-TG. The more posterior the tubercle, the more likely the patient had a cartilage restoration procedure. Surgeons should consider the sTT-TG measurement in patients presenting with anterior knee pain, particularly patellofemoral lesions. III.

Current concept of kinematic alignment total knee arthroplasty and its derivatives.

The kinematic alignment (KA) approach to total knee arthroplasty (TKA) has recently increased in popularity. Accordingly, a number of derivatives have arisen and have caused confusion. Clarification is therefore needed for a better understanding of KA-TKA. Calipered (or true, pure) KA is performed by cutting the bone parallel to the articular surface, compensating for cartilage wear. In soft-tissue respecting KA, the tibial cutting surface is decided parallel to the femoral cutting surface (or trial component) with in-line traction. These approaches are categorized as unrestricted KA because there is no consideration of leg alignment or component orientation. Restricted KA is an approach where the periarthritic joint surface is replicated within a safe range, due to concerns about extreme alignments that have been considered ‘alignment outliers’ in the neutral mechanical alignment approach. More recently, functional alignment and inverse kinematic alignment have been advocated, where bone cuts are made following intraoperative planning, using intraoperative measurements acquired with computer assistance to fulfill good coordination of soft-tissue balance and alignment. The KA-TKA approach aims to restore the patients’ own harmony of three knee elements (morphology, soft-tissue balance, and alignment) and eventually the patients’ own kinematics. The respective approaches start from different points corresponding to one of the elements, yet each aim for the same goal, although the existing implants and techniques have not yet perfectly fulfilled that goal.

Contact Characteristics of Knee-joint Cartilage During Gait Based on Finite Element Analysis

Background: As a common clinical disease, knee osteoarthritis (KOA) is characterized by chronic changes and articular cartilage wear, while the in vivo cartilage contact characteristics of the knee joint during walking are still unclear. It is difficult to implement real-time assistance and treatment for KOA patients accurately. Objective: To investigate the contact biomechanics of knee cartilage during gait and predict the mechanism and location of cartilage damage, aiming to provide theoretical support for real-time rehabilitation assistance for KOA patients. Method: In this study, the subject-specific finite element (FE) method was used to predict the contact characteristics during the stance phase of the gait. A healthy volunteer prepared an intact geometric left knee model based on magnetic resonance scans. The kinematic and dynamic data were collected in a gait experiment and simulated using the personalized musculoskeletal model. Results: Throughout the gait cycle, the contact pressure, contact area and principal Green- Lagrangian strain in the tibiofemoral joint show two obvious peaks concentrated on the 25% and 75% stance phase. The maximum values were 15.32 MPa, 400.607 mm2, and 24.35% on the tibial side, while 15.58 MPa, 683.538 mm2, and 29.68% on the femoral side, respectively. The contact characteristics were significantly greater in the medial compartment than in the lateral. Conclusion: A FE simulation method was developed in this study to forecast the contact characteristics of the human knee joint. The prevention, rehabilitation, and treatment of KOA should focus more on the medial compartment close to the intercondylar eminence, both for the femoral and tibial cartilages.

DEVELOPMENT OF AN ANIMAL-PRODUCT-FREE SYNOVIAL BIOCHIP MODEL AS FIRST STEP TOWARDS MULTI-TISSUE CROSSTALK MODELS IN OSTEOARTHRITIS

Purpose: Knee osteoarthritis (kOA) which has long been regarded as a wear and tear disease of articular cartilage is nowadays considered a whole-joint-disease with multifactorial etiology. In the past years, chronic synovitis has been identified to significantly contribute to kOA progression, aggravating detrimental cellular crosstalk between fibroblast-like synoviocytes (FLS) and chondrocytes due to a constant pro-inflammatory and tissue degrading tissue environment. Given the still unmet need for reliable in vitro disease models of OA, this study aims to establish an authentic human 3D biochip model of synovial joint tissue.

Dopamine-conjugated hyaluronic acid delivered via intra-articular injection provides articular cartilage lubrication and protection

Due to its high molecular weight and viscosity, hyaluronic acid (HA) is widely used for viscosupplementation to provide joint pain relief in osteoarthritis. However, this benefit is temporary due to poor adhesion of HA on articular surfaces. In this study, we therefore conjugated HA with dopamine to form HADN, which made the HA adhesive while retaining its viscosity enhancement capacity. We hypothesized that HADN could enhance cartilage lubrication through adsorption onto the exposed collagen type II network and repair the lamina splendens. HADN was synthesized by carbodiimide chemistry between hyaluronic acid and dopamine. Analysis of Magnetic Resonance (NMR) and Ultraviolet spectrophotometry (Uv–vis) showed that HADN was successfully synthesized. Adsorption of HADN on collagen was demonstrated using Quartz crystal microbalance with dissipation (QCM-D). Ex vivo tribological tests including measurement of coefficient of friction (COF), dynamic creep, in stance (40 N) and swing (4 N) phases of gait cycle indicated adequate protection of cartilage by HADN with higher lubrication compared to HA alone. HADN solution at the cartilage-glass sliding interface not only retains the same viscosity as HA and provides fluid film lubrication, but also ensures better boundary lubrication through adsorption. To confirm the cartilage surface protection of HADN, we visualized cartilage wear using optical coherence tomography (OCT) and atomic force microscopy (AFM).

Shear-responsive boundary-lubricated hydrogels attenuate osteoarthritis

Lipid-based boundary layers formed on liposome-containing hydrogels can facilitate lubrication. However, these boundary layers can be damaged by shear, resulting in decreased lubrication. Here, a shear-responsive boundary-lubricated drug-loaded hydrogel is created by incorporating celecoxib (CLX)-loaded liposomes within dynamic covalent bond-based hyaluronic acid (HA) hydrogels (CLX@Lipo@HA-gel). The dynamic cross-linked network enables the hydrogel to get restructured in response to shear, and the HA matrix allows the accumulation of internal liposome microreservoirs on the sliding surfaces, which results in the formation of boundary layers to provide stable lubrication. Moreover, hydration shells formed surrounding the hydrogel can retard the degradation process, thus helping in sustaining lubrication. Furthermore, in vitro and in vivo experiments found that CLX@Lipo@HA-gels can maintain anabolic-catabolic balance, alleviate cartilage wear, and attenuate osteoarthritis progression by delivering CLX and shear-responsive boundary lubrication. Overall, CLX@Lipo@HA-gels can serve as shear-responsive boundary lubricants and drug-delivery vehicles to alleviate friction-related diseases like osteoarthritis.

The Cartilage Wear Index: a new evaluation method to improve patient selection in surgical treatment of recurrent posterior glenohumeral instability.

BackgroundThe purpose of this study was to validate glenoid cartilage lesions as a negative prognostic factor and to define a new image-based preoperative evaluation method to identify surgical candidates for arthroscopic labral refixation with suture anchors in posterior shoulder instability.MethodsTwenty-six patients who underwent arthroscopic posterior labral repair for shoulder instability were evaluated. Only patients with structural dynamic posterior instability were included. We evaluated on preoperative magnetic resonance arthrogram: glenoid version, humeral head subluxation, type of capsular insertion, and the cartilage lesions using the new Cartilage Wear Index (CWI). Two subgroups were analyzed with regard to the preoperative CWI and shoulder outcome scores: Single Assessment Numerical Evaluation (SANE) and Western Ontario Shoulder Instability Index (WOSI).ResultsThe median age at operation was 28 (interquartile range = 21-33) years. Median overall postoperative outcome assessment demonstrated a SANE of 90 and a WOSI of 385. The median CWI was 1.02. Subgroup analysis revealed worse median WOSI and SANE scores in patients with a CWI >1.02 and a strong correlation between a high preoperative CWI and a higher postoperative WOSI score (R = 0.58; P = .038).ConclusionThe CWI can be useful to identify patients who might obtain better outcomes when treated with arthroscopic labral repair in posterior shoulder instability.

Medial Tibial Osteophyte Width Strongly Reflects Medial Meniscus Extrusion Distance and Medial Joint Space Width Moderately Reflects Cartilage Thickness in Knee Radiographs.

BackgroundThe presence of medial tibial osteophytes on knee radiographs suggests cartilage wear, but may be associated with medial meniscus extrusion (MME). The joint space width of the medial compartment consists anatomically of cartilage and the medial meniscus, but which is most responsible for joint space narrowing remains unclear. Magnetic resonance imaging (MRI) reveals MME and cartilage thickness.PurposesTo determine which radiographic medial tibial osteophyte width correlates better with cartilage thickness or MME distance and which radiographic medial joint space width correlates better with cartilage thickness or MME distance.Study TypeCross‐sectional.PopulationTotal of 527 subjects, 253 females and 274 males, aged 30–79 years, included in the Kanagawa Knee Study.Field Strength/Sequence3 T/fat‐suppressed spoiled gradient echo and proton density weighted.AssessmentThe medial tibial osteophyte width and “the minimum joint space width at the medial compartment” (mJSW) were measured from plain radiographs. The cartilage region was automatically extracted from MRI data using software. The medial femoral and tibial cartilage regions were each divided into nine subregions, and the average thickness of the cartilage was determined in each region and subregion. MME was manually measured by two orthopedic surgeons using MRI coronal section images.Statistical TestsPearson's correlation coefficient and their comparison, with P < 0.05 considered statistically significant.ResultsThe absolute values of the correlation coefficients were 0.33 at maximum between osteophyte width and cartilage thickness and 0.76 between osteophyte width and MME; the value was significantly higher with MME than with cartilage thickness (P < 0.001). The absolute values of the correlation coefficients were 0.50 at maximum between mJSW and cartilage thickness and 0.16 between mJSW and MME; the value was significantly higher with cartilage thickness than with MME (P < 0.001).Data ConclusionThe medial tibial osteophyte width strongly reflected MME and the medial joint space width moderately reflected cartilage thickness.Level of Evidence3Technical Efficacy Stage3

Kinematic alignment matches functional alignment for the extension gap: a consecutive analysis of 749 primary varus osteoarthritic knees with stress radiographs.

The alignment goal in total knee arthroplasty (TKA) remains debated. Two major strategies have emerged based on recreating the native knee: kinematic and functional alignment (KA and FA). Recently a new Coronal Plane Alignment of the Knee (CPAK) classification for KA, based on bony landmarks, was described considering joint line obliquity and the arithmetic HipKneeAnkle angle (aHKA). Valgus corrected HKA medial angle (vcHKA) was measured on distractive valgus preoperative radiographs compensating for cartilage wear and ligament balance in varus osteoarthritis. The purpose of this study was to determine if aHKA accounts for differences in medial laxity for the extension gap by comparing vcHKA to aHKA. The hypothesis was that no significant difference would be observed between the two measurements. This is a retrospective analysis of 749 knees in consecutive patients presenting to a single-centre with primary medial osteoarthritis. Patients underwent standardized weight bearing long-leg and valgus stress radiographs. Tibial mechanical angle (TMA), femoral mechanical angle (FMA) and vcHKA were measured using digital software. aHKA and vcHKA were compared to determine differences due to soft tissue balancing. The mean FMA was 91.3 ± 2.2° (range 82°-97°), the mean TMA was 85.7 ± 2.5° (range 75°-98°), the mean aHKA was 177.0 ± 3.0° (range 164°-185°) and the mean vcHKA was 176.6 ± 3.1° (range 165°-192°). No significant difference was observed between aHKA and vcHKA (p = 0.06). A significant correlation was found between vcHKA and TMA (ρ = 0.3; p < 0.001) and between vcHKA and FMA (ρ = 0.41; p < 0.001). This study showed that vcHKA was similar to aHKA confirming that aHKA accounts for ligamentous medial laxity. Therefore, kinematic alignment based on the CPAK classification matches the pre-arthritic coronal alignment of the knee for the extension gap. IV.

Role of imaging in surgical decision making in young knee osteoarthrosis

Osteoarthrosis is the most common form of knee arthritis, characterized by pain and discomfort from primarily articular cartilage wear. Traditionally in its end stage, it has been treated with total knee arthroplasty, a permanent process with a life span of ten to fifteen years and challenges with revision. With an increasing longevity and epidemic of obesity that the population is facing, naturally, we are seeing more and more patients with osteoarthrosis at a younger age. This makes it imperative to extend the life of the native knee by conservative measures, injections of steroid, hyaluronic acid, or biologicals and finally a slew of surgical alternatives ranging from joint realignment to partial and total joint replacement. Besides the clinical presentation, decisions are made based on joint alignment, extent and degree of cartilage wear and the status of the subchondral bone. Imaging plays an invaluable role in surgical decision making. In this article, we will discuss how imaging is used in our practice during decision making for the management of the young osteoarthritic knee.

A morphologic and morphometric study of articular facets of Patella

Background: The patella plays a major role in flexion and extension of the knee. The patella morphology can be a predisposing factor in patella instability. The congruency between the patella and femur affects the kinematics of the patellofemoral joint, contact mechanics of the patellar cartilage, and strain in the underlying bone, whereby higher stresses and strains potentially contribute to cartilage wear and anterior knee pain. Aim and Objective: The present study was conducted to assess the morphology of facets of patella. Materials and Methods: The present study was conducted to assess the morphology of facets of patella. Ninety-six patella of unknown sex from bone store of Department of Anatomy were included in the study. The patellar morphology and morphometry were investigated. Statistical analysis was performed using the SPSS (v 12.01) software package (SPSS Inc., Chicago, Illinois). Statistical significance was set at P &lt; 0.05. Results: In the present study; 96 patella of unknown sex from bone store of Department of Anatomy were included in the study. The mean size of the right lateral facet was 23.34 mm and left lateral facet patella was 23.06. P value was non-significant. The shape of lateral facet was concave in 93.9% in the left patella and 100% in the right patella. The shape of lateral facet was flat in 6.1% in the left patella and 0% in the right patella. The mean size of the right medial facet was 17.68 mm and left medial facet patella was 17.39 mm. P value was nonsignificant. The shape of medial facet was concave in 2% in the left patella and 10.6% in the right patella. The shape of medial facet was convex in 69.4% in the left patella and 61.7% in the right patella. The shape of medial facet was flat in 28.6% in the left patella and 27.6% in the right patella. P value was non-significant. Conclusion: The present study concluded that the mean size of the right lateral facet was more left lateral facet patella. The shape of lateral facet was concave in 93.9% in the left patella and 100% in the right patella. The shape of lateral facet was flat in 6.1% in the left patella and 0% in the right patella. The mean size of right medial facet was more than left medial facet patella. The shape of medial facet was concave in 2% in the left patella and 10.6% in the right patella. The shape of medial facet was convex in 69.4% in the left patella and 61.7% in the right patella. The shape of medial facet was flat in 28.6% in the left patella and 27.6% in the right patella.

ON RANDOM EXPECTED VALUES VARIATIONS OF TRIBOLOGY PARAMETERS IN HUMAN HIP JOINT SURFACES

This paper presents recent progress in the knowledge concerning the stochastic theory of bio- hydrodynamic lubrication with a phospholipids bilayer. On the basis of experimental measurements and analytical solutions, the research concerns the determination of the random expectancy values of load carrying capacity, the friction coefficient, and synovial fluid dynamic variations. After numerous measurements, it directly follows that the random density function of the gap height in the human joint usually indicates a disorderly increases and decreases in the height. Such irregular gap height variations have an important influence on the random synovial bio-fluid dynamic viscosity. This finally leads to the friction coefficient and cartilage wear changes of cooperating bio- surfaces. The main topic of this paper relates to the expectancy values of the tribology parameters localized inside the variable stochastic standard deviation intervals of the human joint gap height. The results obtained finally indicate the influence of the random roughness and growth of living biological cartilage surfaces on the expectancy values of the synovial fluid dynamic viscosity, load carrying capacity and friction forces in human hip joints.

Polycarbonate-urethane coating can significantly improve talus implant contact characteristics

Talus implants can be utilized in cases of talus avascular necrosis and has been regarded as a promising treatment method. However, existing implants are made of stiff materials that directly oppose natural cartilage. The risk of long-term cartilage wear and bone fracture from the interaction between the cartilage and stiff implant surfaces has been documented in post-hemiarthroplasty of the hip, knee and ankle joints.The aim is to explore the effects of adding a layer of compliant material (polycarbonate-urethane; PCU) over a stiff material (cobalt chromium) in talus implants. To do so, we obtained initial ankle geometry from four cadaveric subjects in neutral standing to create the finite element models. We simulated seven models for each subject: three different types of talus implants, each coated with and without PCU, and a biological model. In total, we constructed 28 finite element models. By comparing the contact characteristics of the implant models with their respective biological model counterparts, our results showed that PCU coated implants have comparable contact area and contact pressure to the biological models, whereas stiff material implants without the PCU coating all have relatively higher contact pressure and smaller contact areas. These results confirmed that adding a layer of compliant material coating reduces the contact pressure and increases the contact area which in turn reduces the risk of cartilage wear and bone fracture. The results also suggest that there can be clinical benefits of adding a layer of compliant material coating on existing stiff material implants, and can provide valuable information towards the design of more biofidelic implants in the future.

3D Printing of Collagen/Oligomeric Proanthocyanidin/Oxidized Hyaluronic Acid Composite Scaffolds for Articular Cartilage Repair.

Articular cartilage defects affect millions of people worldwide, including children, adolescents, and adults. Progressive wear and tear of articular cartilage can lead to progressive tissue loss, further exposing the bony ends and leaving them unprotected, which may ultimately cause osteoarthritis (degenerative joint disease). Unlike other self-repairing tissues, cartilage has a low regenerative capacity; once injured, the cartilage is much more difficult to heal. Consequently, developing methods to repair this defect remains a challenge in clinical practice. In recent years, tissue engineering applications have employed the use of three-dimensional (3D) porous scaffolds for growing cells to regenerate damaged cartilage. However, these scaffolds are mainly chemically synthesized polymers or are crosslinked using organic solvents. Utilizing 3D printing technologies to prepare biodegradable natural composite scaffolds could replace chemically synthesized polymers with more natural polymers or low-toxicity crosslinkers. In this study, collagen/oligomeric proanthocyanidin/oxidized hyaluronic acid composite scaffolds showing high biocompatibility and excellent mechanical properties were prepared. The compressive strengths of the scaffolds were between 0.25–0.55 MPa. Cell viability of the 3D scaffolds reached up to 90%, which indicates that they are favorable surfaces for the deposition of apatite. An in vivo test was performed using the Sprague Dawley (SD) rat skull model. Histological images revealed signs of angiogenesis and new bone formation. Therefore, 3D collagen-based scaffolds can be used as potential candidates for articular cartilage repair.

Water-in-Water Emulsions, Ultralow Interfacial Tension, and Biolubrication

Water-in-Water Emulsions, Ultralow Interfacial Tension, and Biolubrication

Attachment of cartilage wear particles to the synovium negatively impacts friction properties

Cartilage wear particles are released into the synovial fluid by mechanical and chemical degradation of the articular surfaces during osteoarthritis and attach to the synovial membrane. Accumulation of wear particles could alter key tissue-level mechanical properties of the synovium, hindering its characteristically low-friction interactions with underlying articular surfaces in the synovial joint. The present study employs a custom loading device to further the characterization of native synovium friction properties, while investigating the hypothesis that attachment of cartilage wear particles increases friction coefficient. Juvenile bovine synovium demonstrated characteristically low friction coefficients in sliding contact with glass, in agreement with historical measurements. Friction coefficient increased with higher normal load in saline, while lubrication with native synovial fluid maintained low friction coefficients at higher loads. Cartilage wear particles generated from juvenile bovine cartilage attached directly to synovium explants in static culture, with incorporation onto the tissue denoted by cell migration onto the particle surface. In dilute synovial fluid mimicking the decreased lubricating properties during osteoarthritis, wear particle attachment significantly increased friction coefficient against glass, and native cartilage and synovium. In addition to providing a novel characterization of synovial joint tribology this work highlights a potential mechanism for cartilage wear particles to perpetuate the degradative environment of osteoarthritis by modulating tissue-level properties of the synovium that could impact macroscopic wear as well as mechanical stimuli transmitted to resident cells.

The Role of Imaging in Femoroacetabular Impingement: History, Current Practices, and Future Applications.

Femoroacetabular impingement (FAI) is one of the most common causes of early hip articular cartilage wear and labral damage, and subsequently leads to the onset of hip osteoarthritis. Cam-type FAI impingement lesions can be best identified with a 90° Dunn lateral radiograph and a cross-table lateral radiograph with 15° of internal rotation; the alpha angle and the femoral head-neck offset are the most used predictive radiographic markers. FAI lesions with pincer impingement are associated with acetabular retroversion and are more difficult to identify on traditional radiographic imaging; however, the presence of a crossover sign, an ischial spine sign, and/or a posterior wall sign can be useful radiographic markers. Advanced imaging modalities such as magnetic resonance imaging (MRI) and/or magnetic resonance arthrography (MRA) can also be beneficial in the evaluation of FAI and labral pathology; MRA is more sensitive than MRI in detecting intra-articular pathology. Computer-assisted navigation for preoperative planning and intraoperative surgical assistance are promising technologies; however, additional studies are needed before they can be utilized safely and effectively.

Primary Elbow Osteoarthritis: Evaluation and Management

Most patients with primary osteoarthritis of the elbow report a history of heavy lifting with the affected upper extremity. Conservative treatment, including activity modifications, nonsteroidal anti-inflammatory drugs and the occasional intraarticular corticosteroid injection, may provide adequate pain relief in earlier stages. When surgery is required, and despite the presence of cartilage wear, many patients with primary elbow osteoarthritis experience substantial pain improvement with joint preserving procedures. The ulnar nerve needs to be carefully assessed and addressed at the time of surgery. Although open debridement procedures are effective, arthroscopic osteocapsular arthroplasty has emerged as the surgical procedure of choice. Total elbow arthroplasty is very successful in terms of pain relief and function, but it is reserved for patients with end-stage osteoarthritis who are relatively older and have failed joint preserving procedures.

An experimental simulation model to assess wear of the porcine patellofemoral joint.

A range of surgical techniques and osteochondral interventions have been developed for early stage chondral/osteochondral repair interventions in the knee however, methods for functional, pre-clinical assessment of these therapies are limited. In this study, a method for simulating physiological loading and motion in the porcine patellofemoral joint was developed using a 6-axis simulator. As an example of how the method can be used, the influence of surgical positioning of osteochondral allografts in the patella on cartilage wear, deformation and damage and graft stability was investigated in this porcine patellofemoral joint model. The functional performance of allografts implanted either optimally (flush with the cartilage surface) or 1 mm proud of the cartilage surface was compared to a positive control (stainless steel pin implanted 1 mm proud of the cartilage surface), a negative control (no intervention) and a defect model. Allografts implanted flush with the surrounding cartilage could restore the articulating surface of the patella resulting in low wear, damage and deformation of the opposing cartilage surface, similar to that of the negative control group. Implanting the graft proud of the patella surface resulted in cartilage lesions on the femoral trochlea (ICRS grade 2) and a cartilage volume difference of 2.0 ± 3.9 mm3; the positive controls resulted in more severe lesions, a higher volume difference (14.2 ± 7.4 mm3) which in some cases exposed subchondral bone (ICRS grade 4). Defects in the patella caused deformation of the opposing cartilage surface. All grafts implanted in the patella subsided over the duration of the study. This study demonstrated a method that can be used to evaluate osteochondral repair strategies in the patellofemoral joint applying physiological loading and motions.