Os estudos na área de engenharia de tecidos aplicada à reparação da cartilagem articular estão voltados ao desenvolvimento de uma matriz biocompatível que permita a diferenciação, proliferação e manutenção de células para produção de cartilagem hialina. A quitosana é um biomaterial e vem sendo estudada como suporte para condrócitos e para liberação controlada de substâncias. O objetivo deste trabalho foi estudar a biocompatibilidade do gel de quitosana associada ao fosfato de glicerol para reparação de defeitos osteocondrais induzidos experimentalmente na tróclea do talus de eqüinos. Foram utilizados cinco cavalos da raça Mangalarga, de três anos de idade, e por artroscopia foi criado um defeito osteocondral na tróclea lateral do talus de cada articulação. De forma aleatória um defeito foi escolhido para implante do gel de quitosana - fosfato de glicerol, e o defeito da articulação contralateral foi mantido vazio, servindo como controle. Para acompanhamento da evolução do processo de reparação da cartilagem articular foram realizados os exames físico, radiográfico e ultrassonográfico; análise do líquido sinovial (física, celularidade, quantificação de proteína, condroitim sulfato e ácido hialurônico); e análise da cartilagem articular (histológica e produção de proteoglicanos). Os resultados obtidos de todas as avaliações realizadas foram semelhantes entre os defeitos tratados e controle. O gel de quitosana fosfato de glicerol é biocompatível com o ambiente articular e pode ser indicado para futuras aplicações como suporte de células e para liberação controlada de medicamentos. / The tissue engineering studies applied to articular cartilage repair are focused on the development of scaffold biocompatibility allowing the differentiation, proliferation and cells maintenance providing production of the hyaline cartilage. Chitosan is a biomaterial that has been evaluated as a scaffold for chondrocyts implant and also as a drug-delivery control material. The aim of this work was to evaluate the chitosan glycerol phosphate gel biocompatibility in experimentally induced equine talus osteochondral defect. Five three years old Mangalarga breed horses were submitted to arthroscopy for osteochondral defect production on the lateral troclea of the talus in both tibiotarsal joints by arthroscopy. In a random form one defect was chosen for chitosan-glycerol phosphate gel implant, and the defect of the opposed joint was kept empty and used as a control. For the assessment of the articular cartilage repair process was performed the physic, radiographic and ultrassonographic exams; the synovial fluid analyze (physic, cellularity, protein quantification, chondroitin sulphate and hialuronan); and the articular cartilage analyze (hystologic and proteoglicans production). The results obtained in all evaluations performed were similar between the treated and control defects. The chitosan glycerol phosphate gel is biocompatible with the articular environment and can be indicate for future applications as an scaffold for cells support and drug-delivery control system.

A osteocondrose é uma das principais doenças ortopédicas de desenvolvimento que acomete os equinos, sendo usualmente definida como uma falha no processo de ossificação endocondral. Infelizmente os seus mecanismos não estão bem definidos, mas acredita-se em uma etiologia multifatorial relacionada com predisposição genética, desequilíbrio ou excesso nutricional, fatores endócrinos e forças biomecânicas atuando nas articulações. Uma das formas de manifestação da osteocondrose é a osteocondrite dissecante, quando, após interrupção do processo de ossificação, há um desarranjo das colunas de condrócitos e necrose da camada basal, gerando uma área de fragilidade, onde forças biomecânicas podem resultar na separação de fragmentos cartilaginosos ou osteocondrais. Sua incidência esta relacionada com animais jovens, de crescimento rápido, em articulações predispostas como tibiotársica, metacarpo/metatarsofalangeana e femurotibiopatelar. Normalmente a lesão se desenvolve no primeiro ano de vida, mas os sinais clínicos podem aparecer mais tardiamente ou inclusive passarem despercebidos. Dentro dos sinais clínicos o mais comum é a efusão articular, que pode vir ou não associada à claudicação. O diagnóstico é confirmado através de exame radiográfico, com alterações em locais predispostos para formação de OCD, como crista intermédia da tíbia, cristal troclear lateral do talus, bordo dorsoproximal da primeira falange, bordo plantaromedial da primeira falange e crista troclear lateral do fêmur. Como essas lesões podem acometer mais de um membro locomotor, a articulação contralateral deve ser radiografada ou até mesmo os quatro membros quando se tratar de metacarpo/ metatarsofalangeana. Apesar de existirem diversas formas de tratamento, a maioria dos autores recomenda a retirada cirúrgica via artroscópica, já que esta possui um maior índice de sucesso com melhores resultados funcional e estético. Existem trabalhos divergentes com relação ao prognóstico e momento em que se deve submeter esses animais a cirurgia. Com o objetivo de responder essas dúvidas e apresentar os resultados obtidos com o tratamento cirúrgico a médio e longo prazo este trabalho foi realizado. Nesse estudo foram analisados 75 casos de animais acometidos por OCD, com um total de 106 articulações, tratados cirurgicamente, nos quais a cirurgia ocorreu há um tempo mínimo de 12 meses e máximo de 5 anos. As lesões acometeram principalmente (65%) animais até quatro anos, na fase anterior à doma ou no momento da doma (63%), sendo que a maioria não apresentava sinais clínicos (36%) ou apresentava claudicação associada à efusão articular (33%). A maioria das lesões se localizou na articulação tibiotársica (57%), e nessa articulação o local mais acometido foi a crista intermédia da tíbia (71%). Após o procedimento cirúrgico 72% dos animais não apresentaram sinais clínicos, sendo que a melhora foi mais significativa nos animais de 3 e 4 anos (100%) e pouco se obteve de melhora com relação a claudicação nos animais acima de 6 anos (27%). / Osteochondrosis is a major developmental orthopedic disease affecting horses and is usually defined as a failure in the endochondral ossification process. Unfortunately its mechanisms are not defined but it is believed to be a multifactorial etiology related to a genetic predisposition, nutritional imbalance or excess, endocrine factors and biomechanical forces acting on the joints. Osteochondritis dissecans, one of the presentations of osteochondrosis, occours when after stopping the process of ossification, there is a breakdown of the chondrocytes columns and necrosis of the basal layer, creating an area of weakness, where biomechanical forces when applied can result in the separation of cartilage or osteochondral fragments. Its incidence is related to foals with rapid growth, in predisposed joints as tarsocrural, metacarpal/ metatarsalphalangeal and femorotibiopatellar. Usually the lesion develops in the first year of life, but clinical signs may appear later or even go unnoticed. Within the clinical signs, joint effusion is the most common, which may come or not associated with lameness. The diagnosis is confirmed by radiographic examination including changes in prone locations to OCD formation, as intermediate ridge of the tibia, lateral ridge trochlear of the talus, dorsal proximal edge of the first phalanx, plantar medial edge of the first phalanx and the lateral trochlear ridge of the femur. Because these lesions may involve more than one limb, the contralateral joint should be radiographed or even four limbs in the metacarpal/ metatarsalphalangeal. Although there are various forms of treatment most authors recommend surgical excision arthroscopically as this has a higher success rate with best functional and cosmetic results. There are conflicting studies concerning prognosis and best time to refer the animal for surgery. To answer these questions and present the results obtained with surgical treatment in the medium and long term this work was done. In this study we analyzed 75 cases of horses suffering from OCD, with a total of 106 joints treated surgically, which where the treated took place over a minimum of 12 months and a maximum of five years. OCD affected mainly animals up to 4 years (65%) in the period prior to tame or time-taming (63%), and the majority had no clinical signs (36%) or had lameness associated with joint effusion (33%). Most lesions were located in the tarsocrural joint (57%), in the intermediate ridge of the tibia (71%). After surgery 72% of horses showed no clinical signs, and the improvement was more significant in animals 3 and 4 years (100%) and little improvement of lameness in the animals over six years (27%).

The purpose of the present study is to develop techniques for manufacturing anatomically-shaped substrates of implants made from calcium polyphosphate (CPP) ceramic. These substrates have tissue-engineered cartilage growing on their top surfaces and can be used as implants for osteochondral focal defect repair. While many research groups have been fabricating such substrates using standard material shapes, e.g., rectangles and circular discs, it is considered beneficial to develop methods that can be integrated in the substrate fabrication process to produce an implant that is specific to a patient’s own anatomy (as obtained from computer tomography data) to avoid uneven and/or elevated stress distribution that can affect the survival of cartilage. The custom-made, porous CPP substrates were fabricated with three-dimensional printing (3DP) and computer numerically controlled (CNC) machining for the first time to the best of the author’s knowledge. The 3DP technique was employed in two routines: indirect- and direct-3DP. In the former, 3DP was used to fabricate molds for pre-shaping of the CPP substrates from two different powder size ranges (<75 μm and 106-150 μm). In the latter, CPP substrates were produced directly from the retrofitted 3DP apparatus in a layer-by-layer fashion from 45-75 μm CPP powder with a polymeric binder. The prototyped samples were then sintered to obtain the required porosity and mechanical properties. These substrates were characterized in terms of their dimensional shrinkage and density. Also, SEM images were used to assess the particle distribution and neck and bond formations. The substrates produced using the indirect-3DP method yielded densities (<75 μm: 66.28 ± 11.62% and 106-150 μm: 65.87 ± 6.12%), which were comparable to the substrates used currently and with some success in animal studies. Geometric adjustment factors were devised to compensate for the slight expansion inherent in the 3DP mold fabricating process. These equations were used to bring the plaster molds into true dimension. The direct-3DP method has proven to be the ultimate choice due to its ability to produce complex anatomically-shaped substrates without the use of a chemical solvent. In addition, it allows for precise control of both pore size and internal architectures of the substrates. Thus, the direct-3DP was considered to be superior than the indirect-3DP as a fabrication method. In the alternative CNC machining approach to fabrication, the ability to machine the CPP ceramic was feasible and by careful selection of the machining conditions, anatomically-shaped CPP substrates were produced. To develop strategies for optimizing the machining process, a mechanistic model was developed based on curve fitting the average cutting forces to determine the cutting coefficients for CPP. These cutting coefficients were functions of workpiece material, axial depth of cut, chip width, and cutter geometry. To explore the utility of this modelling approach, cutting forces were predicted for a helical ball-end mill and compared with experimental results. The cutting force simulation exhibits good agreement in predicting the fundamental force magnitude and general shape of the actual forces. However, there were some discrepancies between the predicted and measured forces. These differences were attributed to internal microstructure defects, density gradients, and the use of a shear plane model in force prediction that was not entirely appropriate for brittle materials such as CPP. The present study successfully developed 3DP and CNC fabrication methods for manufacturing anatomically-shaped CPP substrates. Future studies were recommended to explore further optimization of these fabrication methods and to demonstrate the utility of accurate substrates shapes to the clinical application of focal defect repair implants.

The purpose of the present study is to develop techniques for manufacturing anatomically-shaped substrates of implants made from calcium polyphosphate (CPP) ceramic. These substrates have tissue-engineered cartilage growing on their top surfaces and can be used as implants for osteochondral focal defect repair. While many research groups have been fabricating such substrates using standard material shapes, e.g., rectangles and circular discs, it is considered beneficial to develop methods that can be integrated in the substrate fabrication process to produce an implant that is specific to a patient’s own anatomy (as obtained from computer tomography data) to avoid uneven and/or elevated stress distribution that can affect the survival of cartilage. The custom-made, porous CPP substrates were fabricated with three-dimensional printing (3DP) and computer numerically controlled (CNC) machining for the first time to the best of the author’s knowledge. The 3DP technique was employed in two routines: indirect- and direct-3DP. In the former, 3DP was used to fabricate molds for pre-shaping of the CPP substrates from two different powder size ranges (<75 μm and 106-150 μm). In the latter, CPP substrates were produced directly from the retrofitted 3DP apparatus in a layer-by-layer fashion from 45-75 μm CPP powder with a polymeric binder. The prototyped samples were then sintered to obtain the required porosity and mechanical properties. These substrates were characterized in terms of their dimensional shrinkage and density. Also, SEM images were used to assess the particle distribution and neck and bond formations. The substrates produced using the indirect-3DP method yielded densities (<75 μm: 66.28 ± 11.62% and 106-150 μm: 65.87 ± 6.12%), which were comparable to the substrates used currently and with some success in animal studies. Geometric adjustment factors were devised to compensate for the slight expansion inherent in the 3DP mold fabricating process. These equations were used to bring the plaster molds into true dimension. The direct-3DP method has proven to be the ultimate choice due to its ability to produce complex anatomically-shaped substrates without the use of a chemical solvent. In addition, it allows for precise control of both pore size and internal architectures of the substrates. Thus, the direct-3DP was considered to be superior than the indirect-3DP as a fabrication method. In the alternative CNC machining approach to fabrication, the ability to machine the CPP ceramic was feasible and by careful selection of the machining conditions, anatomically-shaped CPP substrates were produced. To develop strategies for optimizing the machining process, a mechanistic model was developed based on curve fitting the average cutting forces to determine the cutting coefficients for CPP. These cutting coefficients were functions of workpiece material, axial depth of cut, chip width, and cutter geometry. To explore the utility of this modelling approach, cutting forces were predicted for a helical ball-end mill and compared with experimental results. The cutting force simulation exhibits good agreement in predicting the fundamental force magnitude and general shape of the actual forces. However, there were some discrepancies between the predicted and measured forces. These differences were attributed to internal microstructure defects, density gradients, and the use of a shear plane model in force prediction that was not entirely appropriate for brittle materials such as CPP. The present study successfully developed 3DP and CNC fabrication methods for manufacturing anatomically-shaped CPP substrates. Future studies were recommended to explore further optimization of these fabrication methods and to demonstrate the utility of accurate substrates shapes to the clinical application of focal defect repair implants.

There are more than 150,000 anterior cruciate ligament reconstructions each year with the goal of recovering the balance between knee stability and mobility. As many as 25 percent of these procedures will end in joint instability that can cause further damage. The risk of developing degenerative joint disease (DJD) increases in patients with previous knee injury, resulting in a higher instance of total knee arthroplasty (TKA). There are more than 400,000 TKA procedures each year, but the waiting lists for this surgery shows that many more patients are hoping to undergo this procedure. TKA provides improved knee function and pain relief for patients suffering from DJD. Although this procedure is considered successful, as younger patients undergo this treatment, the long-term performance must be improved. Major mechanisms of failure include component loosening from stress-shielding, poor integration of the implant with native tissue, and ion release from the implant. TiNb alloys are more biocompatible than currently used alloys, such as NiTi, and have mechanical properties closer to bone, so they would reduce the instance of stress shielding. TiNb can be made porous for better integration with the native bone and has superior corrosion resistance than NiTi. Engineered ligaments have generally failed to achieve mechanical properties sufficiently similar to their native counterparts, but also lack the osteochondral interface critical to the transfer of load between ligament and bone. The osteochondral interface could be incorporated through a gradient of inorganic content toward the bony insertion ends of the ligament graft, as we showed that in increase of inorganic content resulted in the transdifferentiation of osteoblasts toward chondrocyte-like cells (bone to cartilage-like). A composite scaffold composed of an electrospun mesh with either a hydrogel component or extracellular matrix (ECM) produced by the cells may be a suitable tissue engineered ligament graft. The non-linear stress-strain behavior seen in native ligament is exhibited by both of these systems, and the ECM produced by these systems is consistent with ligament tissue. The ECM-electrospun mesh composite exhibited higher elastic modulus than the fibrin-electrospun mesh composite, but required extensive pre culture while the fibrin-electrospun mesh composite could be fabricated in situ.

Patient expectations have been shown to be a major predictor of outcomes. Furthermore, fulfilled expectations have been linked to increased patient satisfaction and rehabilitation adherence. Expectations may be influenced by a variety of factors, including patient characteristics, pre-operative function, or disease characteristics. However, it is currently unknown what factors and to what degree they may influence patient expectations prior to knee surgery. Furthermore, understanding the importance and values of those expectations for recovery using qualitative methods has not previously been conducted in this patient population. A mixed methods design was used. Twenty-one participants scheduled to undergo cartilage repair of the knee, including autologous chondrocyte implantation, osteochondral allograft transplantation, or meniscal transplant were included. During their pre-operative visit, participants completed an expectations survey (Hospital for Special Surgery (HSS) Knee Surgery Expectations Survey) and the Knee Injury and Osteoarthritis Outcome Score (KOOS) as a measure of functional ability. At their first post-operative visit, patients completed the Self-Efficacy for Rehabilitation Scale (SER). Rehabilitation adherence was collected by the participant’s rehabilitation provider. A selected sample of 6 participants participated in a semi-structured interview 6 months following surgery to better understand their expectations for recovery. Pearson correlation coefficients were used to determine relationships between expectations and KOOS scores, SER scores, and measures of adherence. Results demonstrated that patients have moderate expectations for recovery and these expectations were positively associated with pre-operative pain, activities of daily living, and knee-related quality of life as measured by the KOOS. In addition, a negative relationship was found between patient expectations and adherence with home exercises, use of a brace, and weight-bearing restrictions. Four qualitative themes emerged as participants’ described how previous recovery experiences shaped their recovery following cartilage repair of the knee. Patient education, pre-habilitation, and the use of psychological skills during rehabilitation may help to manage patient expectations, improve rehabilitation adherence, and assist clinicians in providing more focused and individualized patient care.

A osteocondrose é uma das principais doenças ortopédicas de desenvolvimento que acomete os equinos, sendo usualmente definida como uma falha no processo de ossificação endocondral. Infelizmente os seus mecanismos não estão bem definidos, mas acredita-se em uma etiologia multifatorial relacionada com predisposição genética, desequilíbrio ou excesso nutricional, fatores endócrinos e forças biomecânicas atuando nas articulações. Uma das formas de manifestação da osteocondrose é a osteocondrite dissecante, quando, após interrupção do processo de ossificação, há um desarranjo das colunas de condrócitos e necrose da camada basal, gerando uma área de fragilidade, onde forças biomecânicas podem resultar na separação de fragmentos cartilaginosos ou osteocondrais. Sua incidência esta relacionada com animais jovens, de crescimento rápido, em articulações predispostas como tibiotársica, metacarpo/metatarsofalangeana e femurotibiopatelar. Normalmente a lesão se desenvolve no primeiro ano de vida, mas os sinais clínicos podem aparecer mais tardiamente ou inclusive passarem despercebidos. Dentro dos sinais clínicos o mais comum é a efusão articular, que pode vir ou não associada à claudicação. O diagnóstico é confirmado através de exame radiográfico, com alterações em locais predispostos para formação de OCD, como crista intermédia da tíbia, cristal troclear lateral do talus, bordo dorsoproximal da primeira falange, bordo plantaromedial da primeira falange e crista troclear lateral do fêmur. Como essas lesões podem acometer mais de um membro locomotor, a articulação contralateral deve ser radiografada ou até mesmo os quatro membros quando se tratar de metacarpo/ metatarsofalangeana. Apesar de existirem diversas formas de tratamento, a maioria dos autores recomenda a retirada cirúrgica via artroscópica, já que esta possui um maior índice de sucesso com melhores resultados funcional e estético. Existem trabalhos divergentes com relação ao prognóstico e momento em que se deve submeter esses animais a cirurgia. Com o objetivo de responder essas dúvidas e apresentar os resultados obtidos com o tratamento cirúrgico a médio e longo prazo este trabalho foi realizado. Nesse estudo foram analisados 75 casos de animais acometidos por OCD, com um total de 106 articulações, tratados cirurgicamente, nos quais a cirurgia ocorreu há um tempo mínimo de 12 meses e máximo de 5 anos. As lesões acometeram principalmente (65%) animais até quatro anos, na fase anterior à doma ou no momento da doma (63%), sendo que a maioria não apresentava sinais clínicos (36%) ou apresentava claudicação associada à efusão articular (33%). A maioria das lesões se localizou na articulação tibiotársica (57%), e nessa articulação o local mais acometido foi a crista intermédia da tíbia (71%). Após o procedimento cirúrgico 72% dos animais não apresentaram sinais clínicos, sendo que a melhora foi mais significativa nos animais de 3 e 4 anos (100%) e pouco se obteve de melhora com relação a claudicação nos animais acima de 6 anos (27%). / Osteochondrosis is a major developmental orthopedic disease affecting horses and is usually defined as a failure in the endochondral ossification process. Unfortunately its mechanisms are not defined but it is believed to be a multifactorial etiology related to a genetic predisposition, nutritional imbalance or excess, endocrine factors and biomechanical forces acting on the joints. Osteochondritis dissecans, one of the presentations of osteochondrosis, occours when after stopping the process of ossification, there is a breakdown of the chondrocytes columns and necrosis of the basal layer, creating an area of weakness, where biomechanical forces when applied can result in the separation of cartilage or osteochondral fragments. Its incidence is related to foals with rapid growth, in predisposed joints as tarsocrural, metacarpal/ metatarsalphalangeal and femorotibiopatellar. Usually the lesion develops in the first year of life, but clinical signs may appear later or even go unnoticed. Within the clinical signs, joint effusion is the most common, which may come or not associated with lameness. The diagnosis is confirmed by radiographic examination including changes in prone locations to OCD formation, as intermediate ridge of the tibia, lateral ridge trochlear of the talus, dorsal proximal edge of the first phalanx, plantar medial edge of the first phalanx and the lateral trochlear ridge of the femur. Because these lesions may involve more than one limb, the contralateral joint should be radiographed or even four limbs in the metacarpal/ metatarsalphalangeal. Although there are various forms of treatment most authors recommend surgical excision arthroscopically as this has a higher success rate with best functional and cosmetic results. There are conflicting studies concerning prognosis and best time to refer the animal for surgery. To answer these questions and present the results obtained with surgical treatment in the medium and long term this work was done. In this study we analyzed 75 cases of horses suffering from OCD, with a total of 106 joints treated surgically, which where the treated took place over a minimum of 12 months and a maximum of five years. OCD affected mainly animals up to 4 years (65%) in the period prior to tame or time-taming (63%), and the majority had no clinical signs (36%) or had lameness associated with joint effusion (33%). Most lesions were located in the tarsocrural joint (57%), in the intermediate ridge of the tibia (71%). After surgery 72% of horses showed no clinical signs, and the improvement was more significant in animals 3 and 4 years (100%) and little improvement of lameness in the animals over six years (27%).

Os estudos na área de engenharia de tecidos aplicada à reparação da cartilagem articular estão voltados ao desenvolvimento de uma matriz biocompatível que permita a diferenciação, proliferação e manutenção de células para produção de cartilagem hialina. A quitosana é um biomaterial e vem sendo estudada como suporte para condrócitos e para liberação controlada de substâncias. O objetivo deste trabalho foi estudar a biocompatibilidade do gel de quitosana associada ao fosfato de glicerol para reparação de defeitos osteocondrais induzidos experimentalmente na tróclea do talus de eqüinos. Foram utilizados cinco cavalos da raça Mangalarga, de três anos de idade, e por artroscopia foi criado um defeito osteocondral na tróclea lateral do talus de cada articulação. De forma aleatória um defeito foi escolhido para implante do gel de quitosana - fosfato de glicerol, e o defeito da articulação contralateral foi mantido vazio, servindo como controle. Para acompanhamento da evolução do processo de reparação da cartilagem articular foram realizados os exames físico, radiográfico e ultrassonográfico; análise do líquido sinovial (física, celularidade, quantificação de proteína, condroitim sulfato e ácido hialurônico); e análise da cartilagem articular (histológica e produção de proteoglicanos). Os resultados obtidos de todas as avaliações realizadas foram semelhantes entre os defeitos tratados e controle. O gel de quitosana fosfato de glicerol é biocompatível com o ambiente articular e pode ser indicado para futuras aplicações como suporte de células e para liberação controlada de medicamentos. / The tissue engineering studies applied to articular cartilage repair are focused on the development of scaffold biocompatibility allowing the differentiation, proliferation and cells maintenance providing production of the hyaline cartilage. Chitosan is a biomaterial that has been evaluated as a scaffold for chondrocyts implant and also as a drug-delivery control material. The aim of this work was to evaluate the chitosan glycerol phosphate gel biocompatibility in experimentally induced equine talus osteochondral defect. Five three years old Mangalarga breed horses were submitted to arthroscopy for osteochondral defect production on the lateral troclea of the talus in both tibiotarsal joints by arthroscopy. In a random form one defect was chosen for chitosan-glycerol phosphate gel implant, and the defect of the opposed joint was kept empty and used as a control. For the assessment of the articular cartilage repair process was performed the physic, radiographic and ultrassonographic exams; the synovial fluid analyze (physic, cellularity, protein quantification, chondroitin sulphate and hialuronan); and the articular cartilage analyze (hystologic and proteoglicans production). The results obtained in all evaluations performed were similar between the treated and control defects. The chitosan glycerol phosphate gel is biocompatible with the articular environment and can be indicate for future applications as an scaffold for cells support and drug-delivery control system.

Articular cartilage defects in the knee are common, and can result in pain, decreased function and decreased quality of life. Untreated defects are considered to be a risk factor for developing osteoarthritis, a progressive degenerative joint disease with minimal treatment options. To address these issues, various surgical procedures are available to treat articular cartilage defects in the knee. While these procedures overall have positive results, after surgery patients experience large and persistent deficits in quadriceps strength. A contributing factor to this post-surgical weakness is believed to be the extended post-operative non-weight bearing period, with full weight bearing not initiated until approximately 4 – 6 weeks after surgery. During this non-weight bearing period a minimal amount of demand is placed upon the muscle. Subsequently, the quadriceps muscle undergoes a large degree of atrophy with a significant decrease in muscle strength. Muscular strength deficits reduce the knee joint stability, also increasing the risk of osteoarthritis development. Interventions that can be used to facilitate quadriceps strength while protecting the articular cartilage repair are needed. Neuromuscular electrical stimulation (NMES) is an effective post-knee surgery rehabilitation technique to regain quadriceps musculature. In recent years manufactures have been developing knee sleeve garments integrated with NMES allowing for portability of the NMES treatment. The primary aim of this study was to evaluate the effectiveness of a 12-week home-based neuromuscular electrical stimulation treatment on post-surgical clinical outcomes (quadriceps strength, lower extremity function, and patient reported outcomes) after articular cartilage knee surgery. Patients were randomized between a standard of care home-treatment group and a NMES home-treatment group. Patients completed isometric quadriceps strength testing, the Y-balance test, and the Knee Injury and Osteoarthritis Outcome Score (KOOS) before surgery and at 3-months after surgery. The secondary aims of this study were to determine the most effective NMES parameters for post-surgical quadriceps strength; and to develop a framework to identify factors that may influence a patient’s adherence to a prescribed therapy program. From our results we can make several conclusions. First, we found only a small number of studies utilize similar parameters for post-surgical quadriceps strength treatments. The majority of the parameters reported in the literature were highly variable between studies. Second, clinicians can utilize the expanded Health Belief Model to identify situational and personal factors unique to a patient that may impact adherence to a prescribed treatment. Clinicians can then implement the proposed interventional strategies to address the identified situational and personal factors. Finally, there was no difference in quadriceps strength, lower extremity function, or self-reported scores at 3-month between a home-based NMES treatment and a standard of care home-based treatment. Patients’ adherence to the treatment protocols may have been a major factor contributing to these results. Utilizing a model, such as the proposed expanded Health Belief Model, may assist clinicians in improving a patients’ adherence to future prescribed home-treatment programs.

Articular cartilage injuries occur frequently in the knee joint. Several methods have been implemented clinically, to treat osteochondral defects but none have been able to produce a long term, durable solution. Photopolymerizable cartilage tissue engineering approaches appear promising; however, fundamentally, forming a stable interface between the tissue engineered cartilage and native tissue, mainly subchondral bone and native cartilage, remains a major challenge. The overall objective of this research is to find a solution for the current problem of dislodgment of tissue engineered cartilage at the defect site for the treatment of degraded cartilage that has been caused due to knee injuries or because of mild to moderate level of osteoarthritis. For this, an in-vitro model was created to analyze the integration of tissue engineered cartilage with the bone, healthy and diseased cartilage over time. We investigated the utility of hydroxyapatite (HA) nanoparticles to promote controlled bone-growth across the bone-cartilage interface in an in vitro engineered tissue model system using bone marrow derived stem cells. We also investigated the application of HA nanoparticles to promote enhance integration between tissue engineered cartilage and native cartilage both in healthy and diseased states. Samples incorporated with HA demonstrated significantly higher interfacial shear strength (at the junction between engineered cartilage and engineered bone and also with diseased cartilage) compared to the constructs without HA (p < 0.05), after 28 days of culture. These findings indicate that the incorporation of HA nanoparticles permits more stable anchorage of the injectable hydrogel-based engineered cartilage construct via augmented integration between bone and cartilage.