No description available.

No description available.

The anterior cruciate ligament (ACL) contributes to normal knee function, but it is commonly injured and has poor healing capabilities. Of the current treatments available for ACL reconstruction, none replicate the long-term mechanical properties of the ACL. It was hypothesized that tissue-engineered scaffolds comprised of reconstituted type I collagen fibers would have the potential to yield a more suitable treatment for ACL reconstruction. Ultra-violet (UV) radiation and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) were investigated as possible crosslinking methods for the scaffolds, and EDC crosslinking was deemed more appropriate given the gains in strength and stiffness afforded to individual collagen fibers. Scaffolds were composed of 54 collagen fibers, which were made using an extrusion process, organized in accordance with a braid-twist design; the addition of a hydrogel (gelatin) to this scaffold was also investigated. The scaffolds were tested mechanically to determine ultimate tensile strength (UTS), Young's modulus, and viscoelastic properties. Scaffolds were also evaluated for the cellular activity of primary rat lateral collateral ligament (LCL) and medial collateral ligament (MCL) fibroblast cells after 7, 14, and 21 days. The crosslinked scaffolds without gelatin exhibited mechanical and viscoelastic properties that were more similar to the human ACL. Cellular activity on the crosslinked scaffolds without gelatin was observed after 7 and 21 days, but no significant increase was observed with time. Although more studies are needed, these results indicate that a braid- twist scaffold (composed of collagen fibers) has the potential to serve as a scaffold for ACL replacement. / Master of Science

Majoriteten av idrottsskador inklusive skada på främre korsbandet (Anterior Cruciate Ligament, ACL) uppstår i slutet av träning/tävling när personen tenderar att vara trött. Nuvarande funktionstest inför återgång till idrott efter skada utvärderar ofta individens hoppförmåga i ett icke-uttröttat tillstånd. Syfte: Syftet med följande studie var att se huruvida prestationen i två olika enbenshopp kunde skilja sig mellan före och efter 25 minuters löpning, varav 15 minuter på hög-intensiv nivå och om hopprestationen skiljer sig mellan oskadade och ACL-opererade kvinnor. Metod: Totalt deltog 8 friska kvinnor, utan pågående besvär från nedre extremitet samt 6 färdigrehabiliterade ACL-opererade kvinnor som återgått till sin tidigare aktivitetsnivå. Deltagarna genomförde tester vid två olika tillfällen. Ett Pre-test-tillfälle då inträning av distans- och cross-overhopp samt ett max-pulstest (HRmax) på löpband utfördes. Ett Test-tillfälle där respektive hopp utfördes före och efter cirka 25 minuters löpning varav 15 minuter var på hög-intensiv nivå (>RPE 15 eller >85 % av HRmax). Total distans mättes, registrerades och analyserades för två godkända hopp per ben, tillstånd och hopptyp. Antal hopp-försök per ben och hopp registrerades. Ett symmetri index (LSI) beräknades för att bedöma om det förelåg en normal eller onormal sidoskillnad. Resultat: Cross-overhoppet var signifikant kortare efter löpning jämfört med före. Samma resultat syntes inte för distanshoppet. Ingen skillnad fanns mellan grupperna i hopplängd eller LSI-värden, före eller efter löpning. Ingen onormal sidoskillnad syntes före eller efter löpning i något utav hoppen. ACL-skadade behövde signifikant fler hoppförsök på det opererade benet i uttröttat tillstånd jämfört med det icke-opererade och jämfört med oskadade för att uppnå två godkända hopp. Slutsats: Cross-overhoppet försämrades av löpningen och kan därför sägas vara känsligt nog att kunna skilja uttröttat från icke-uttröttat tillstånd hos båda grupperna. Samma resultat syntes inte för distanshoppet. Det uttröttningsprotokoll och de hopptester som utfördes kunde inte frambringa några större förändringar eller olika sidoskillnader mellan färdigrehabiliterade ACL-opererade kvinnor som återgått till sin tidigare aktivitetsnivå och oskadade, generellt fysisk aktiva kvinnor. Viss osäkerhet kan ha funnits kvar hos det tidigare skadade benet eftersom fler hoppförsök krävdes i uttröttat tillstånd på det opererade benet jämfört med det icke-opererade benet eller jämfört med oskadade deltagare för båda hopptyperna. / Most sport injuries including anterior cruciate ligament-injury (ACL) occur at the end of sport events when the person tends to be fatigued. Despite this, the tests commonly used today to assess whether the individual should return to sports are performed in a non-fatigued state. Aim: The aim of this study was to compare effects of 25 minutes treadmill running, including 15 minutes at a level of high-intenisty on the performance of two different single-leg hop tests between un-injured women and women who underwent an ACL-reconstruction. Method: Eight un-injured women without any ongoing symptoms from either leg, and 6 women who had undergone an ACL-reconstruction, finished the rehabilitation program and returned to their pre-injury level of activity performed tests at two different occasions. The first occasion included technique training for each single-leg hop and a maximal heart rate test (HRmax) on a treadmill. On the second occasion subjects performed the single-leg hop for distance and the cross-over hop before and directly after 25 minutes running, including 15 minutes on a high-intensity level (>RPE 15 and/or >85 % HRmax). Total jump-distance was measured, registered and analysed for 2 approved trials per leg, condition and hop. A leg symmetry index (LSI) was calculated to assess side-to-side-differences. Results: The cross-over hop was significantly shorter after running in both groups, whereas no such effect was seen for the single-leg hop for distance. No difference was shown between groups in performed distance, side-to-side difference or LSI-values, before or after running any of the single-leg hops. Subjects in the ACL-group needed significantly more hop-trials on the operated leg compared to the non-operated leg and compared to un-injured subjects to achieve two qualified hops. Conclusions: Subjects jumped shorter in the cross-over hop after running. This hop can therefore be regarded as sensitive enough to tell fatigued state from a non-fatigued state in both groups. The fatigue protocol did not induce any side-to-side differences in subjects who had undergone ACL-reconstruction, finished their rehabilitation and returned to their pre-injury activity level. Some insecurity may still have been present in the previously injured leg since ACL-operated subjects needed more hop-trials for the operated leg compared to the non-operated leg or compared to un-injured subjects when fatigue.

Em uma tentativa de melhor restabelecer a função normal do ligamento cruzado anterior (LCA), foi proposta a técnica de reconstrução do LCA com feixe duplo (FD). Entretanto, a superioridade desta técnica frente à técnica com feixe simples (FS) ainda não está claramente demonstrada no cenário clínico. O propósito do presente estudo foi avaliar e comparar a amplitude de rotação tibial, o máximo de rotação interna e externa, e a força de reação ao solo de joelhos submetidos à reconstrução anatômica com feixe duplo, a joelhos submetidos à reconstrução com feixe simples, durante a realização de tarefas dinâmicas. Para isso, um total de 75 (setenta e cinco) indivíduos foram avaliados (26 reconstruções feixe duplo, 22 reconstruções feixe simples, 27 indivíduos sem lesão do LCA que formaram um grupo controle). Utilizando um sistema de análise do movimento humano, constituído por 4 câmeras para a análise do movimento, os indivíduos foram avaliados em três tarefas de demandas distintas. Utilizou-se a técnica TSACCAST para o cálculo da rotação interna e externa da tíbia. A média da amplitude de rotação tibial, máximo de rotação interna e externa, foi avaliada para cada joelho em cada um dos três grupos. A avaliação clínica destes pacientes foi realizada utilizando-se questionários subjetivo e objetivo (IKDC), assim como artrometria manual. Estas avaliações revelaram que ambos os grupos operados eram semelhantes no que se refere ao resultado clínico pós-operatório. A avaliação da amplitude de rotação tibial, máximo de rotação interna e externa, demonstrou que o joelho operado era semelhante ao joelho não operado e aos joelhos do grupo controle. Também não se verificou diferença significativa nos valores de amplitude de rotação tibial, máximo de rotação interna e externa, quando se comparou o grupo FS ao grupo FD. Desta forma, concluímos que a reconstrução do LCA com a técnica de FS e com a técnica de FD são similares no que se refere ao restabelecimento do controle da rotação da tíbia / In an attempt to better restore the normal function of the two ACL bundles, the ACL reconstruction with two bundles has been proposed. However, the superiority of the double-bundle technique has not been clearly demonstrated in the clinical setting. The purpose of this study was to compare the tibial rotational range, maximal internal and external rotation and ground reaction force of anatomical double-bundle anterior cruciate ligament reconstructed knees with single-bundle anterior cruciate ligament reconstructed knees during three different demanding tasks. A total of 75 subjects, (26 with double-bundle anterior cruciate ligament reconstruction, 22 with single-bundle anterior cruciate ligament reconstruction, and 27 healthy control individuals) were evaluated in this study. Using a 4-camera motion analysis system, motion subjects were recorded performing during three different tasks. Using the CAST technique, the internal-external tibial rotation of both knees was calculated. The mean tibial rotational range, maximum internal and external rotation, for each knee, was evaluated for the 3 groups (double-bundle group, single-bundle group, and control group). Clinical assessment, including objective and subjective IKDC scores, and knee arthrometric measurement, revealed restoration of the reconstructed knee stability with no differences between the two anterior cruciate ligament reconstruction groups. The results demonstrated that both groups resulted in tibial rotation range values that were similar to those in the non-injured knees and those in the healthy controls. There were also no significant differences in tibial rotational range, maximal internal and external rotation and ground reaction force between the DB group and the SB group. Therefore, anatomical double-bundle and single-bundle reconstruction are able to restore normal tibial rotation

Diss. (sammanfattning) Stockholm : Karol. inst., 2004. / Härtill 4 uppsatser.

Submitted by Diogo Misoguti (diogo.misoguti@gmail.com) on 2016-06-24T19:52:09Z No. of bitstreams: 1 2015-12-doutorado-pedro-debieux-vargas-silva.pdf: 2344545 bytes, checksum: 1ecd3c6040fb5757f7f2df3ba6314152 (MD5) / Approved for entry into archive by Diogo Misoguti (diogo.misoguti@gmail.com) on 2016-06-24T19:52:38Z (GMT) No. of bitstreams: 1 2015-12-doutorado-pedro-debieux-vargas-silva.pdf: 2344545 bytes, checksum: 1ecd3c6040fb5757f7f2df3ba6314152 (MD5) / Made available in DSpace on 2016-06-24T19:52:38Z (GMT). No. of bitstreams: 1 2015-12-doutorado-pedro-debieux-vargas-silva.pdf: 2344545 bytes, checksum: 1ecd3c6040fb5757f7f2df3ba6314152 (MD5) Previous issue date: 2015 / Introdução: Esta revisão avalia se os parafusos de interferência bioabsorvíveis podem apresentar melhores resultados do que os parafusos de interferência metálicos quando utilizados para a fixação do enxerto na reconstrução do LCA. Objetivo: Comparar a efetividade dos parafusos de interferência bioabsorvíveis e metálicos para a fixação do enxerto na reconstrução do ligamento cruzado anterior, através de meta-análise. Métodos: Foram pesquisadas as bases de dados: Cochrane Bone, Joint and Muscle Trauma Group Specialised Register, The Cochrane Library, MEDLINE, EMBASE, LILACS, Current Controlled Trials e the World Health Organization Clinical Trials Registry Platform. Ensaios clínicos randomizados e quasi-randomizado comparando parafusos de interferência bioabsorvíveis com metálicos foram incluídos na pesquisa. Os desfechos primários foram função, qualidade de vida, falhas de tratamento e nível de atividade. Ao menos dois autores selecionaram estudos elegíveis e avaliaram de forma independente o risco de viés. Os dados relevantes foram agrupados. Resultados: Onze ensaios envolvendo 981 participantes foram incluídos na revisão. Em relação à função (avaliada pelo Lysholm), quatro ensaios clínicos (220 participantes) não mostraram diferenças entre os dois métodos de fixação com 12 ou 24 meses de seguimento: MD -026, IC 95%, -1,63 a 1,11 e MD 1,10, IC 95% -1,44 a 1,64, respectivamente. Quando realizada a análise de subgrupos do Lysholm, entretanto, foi observada diferença estatística favorável ao parafuso metálico, quando o parafuso bioabsorvível era constituído por Ácido-L-Polilático (PLLA): RR -4,00, 95% CI -7,59 a -0,41. Três estudos com 24 meses (RR 1,00, 95% CI 0,81-1,24) e dois estudos com 12 meses de seguimento (RR 1,01, 95% CI 0,94-1,08) não mostraram diferenças no IKDC. Em relação ao nível de atividade (analisado pelo Tegner), dois estudos (117 participantes) com 12 meses, e três estudos com 24 meses de seguimento não evidenciaram diferenças entre o grupo bioabsorvível e o grupo que usou parafuso de metal: MD 0.08, 95% CI -0,39 a 0,55 e MD 0,41, IC 95% -0,23 a 1,05, respectivamente. Na análise de subgrupos, houve diferença estatística favorável ao parafuso de PLLA: RR 1,27, 95% CI 0,49 a 3,30. Apesar da diferença estatística, em nenhum dos desfechos supracitados observou-se relevância clínica. Em relação às falhas de tratamento, foi demonstrada uma diferença significativa entre os dois métodos de fixação, quando considerada a quebra de implante (RR 7,06, 95% CI 1,31-2,75) e quanto ao risco global de falha do tratamento (RR 1,89, 95% CI 1,31-2,75), tendo o parafuso bioabsorvível mais falhas nestes aspectos. Em oposição, não houve diferença significativa para estabilidade, testes funcionais, derrame articular, re-lesões, infecção, reação de corpo estranho, dor ou limitação de movimento. Conclusão: Não há evidência que demonstre diferença de efetividade entre parafusos de interferência metálicos com relação aos bioabsorvíveis para fixação do enxerto na reconstrução do ligamento cruzado anterior quanto a função, qualidade de vida e o nível de atividade; entretanto, há evidências de que parafusos bioabsorvíveis estão associados a mais falhas de tratamento global e quebra do implante. Os ensaios clínicos randomizados presentes na literatura fornecem evidências de moderada/baixa qualidade. / Introduction: This review assesses whether bioabsorbable interference screws may show better results than metal ones when used for fixing the graft in the reconstruction of the anterior cruciate ligament (ACL). Objective: To compare the effects of bioabsorbable and metal interference screws for fixing the graft in the reconstruction of the anterior cruciate ligament, by metaanalysis. Methods: The following databases were searched: Cochrane Bone, Joint and Muscle Trauma Group Specialised Register, The Cochrane Library, MEDLINE, EMBASE, LILACS, Current Controlled Trials and the World Health Organization International Clinical Trials Registry Platform. Randomized controlled trials and quasi-randomized trials comparing bioabsorbable with metal interference screws were included in the survey. Primary outcome measures were function, quality of life, treatment failures and activity level. At least two authors selected eligible studies and independently assessed the risk of bias. The relevant data were pooled. Results: Eleven trials involving 981 participants were included in the review. Regarding the function (assessed by Lysholm), four trials (220 participants) showed no differences between the two fixation methods with 12 or 24 months of follow-up: MD -026, CI 95% -1.63 - 1.11 and MD 1.10, CI 95% - 1.44 to 1.64, respectively. However, when subgroup analysis using Lysholm score was performed, statistical difference was observed favoring the metal screw when the bioabsorbable screw was comprised of L-polylactic acid (PLLA): RR -4.00, CI 95%, -7.59 - -0.41. Three studies at 24 months (RR 1.00, 95% CI 0.81 to 1.24) and two studies at 12 months follow-up (RR 1.01, 95% CI 0.94 to 1.08) showed no differences the in the IKDC. Regarding the level of activity (analyzed by Tegner activity level scale), two studies (117 participants) at 12 months and three studies at 24 months follow-up showed no differences between the bioabsorbable group and the group using metal screws: MD 0.08, 95 % CI -0.39 to 0.55 and MD 0.41, 95% CI -0,23-1,05 respectively. In the subgroup analysis, a statiscally favorable difference was found for the PLLA screw: RR 1.27, 95% CI 0.49 to 3.30. Despite the statistical differences, none of the above outcomes has presented clinical relevance. With regard to treatment failures, a significant difference was found between the two methods of attachment, when considering the implant breaks (RR 7.06, 95% CI 1.31 to 2.75) and the overall risk of failure (RR 1.89, CI 95% 1.31 to 2.75), with the bioabsorbable screw having more failures in these respects. In contrast, there was no significant difference in stability, functional testing, joint effusion, re-injury, infection, foreign body reaction, pain or limitation of movement. Conclusion: There is no evidence that demonstrates an effective difference between metal and bioabsorbable interference screws for graft fixation in the reconstruction of the anterior cruciate ligament when considering function, quality of life and level of activity. However, there is evidence that bioabsorbable screws are associatewith more failures in the global treatment as well as breaks of the implant. Clinical trials in the literature provide moderate / low quality evidence.

Em uma tentativa de melhor restabelecer a função normal do ligamento cruzado anterior (LCA), foi proposta a técnica de reconstrução do LCA com feixe duplo (FD). Entretanto, a superioridade desta técnica frente à técnica com feixe simples (FS) ainda não está claramente demonstrada no cenário clínico. O propósito do presente estudo foi avaliar e comparar a amplitude de rotação tibial, o máximo de rotação interna e externa, e a força de reação ao solo de joelhos submetidos à reconstrução anatômica com feixe duplo, a joelhos submetidos à reconstrução com feixe simples, durante a realização de tarefas dinâmicas. Para isso, um total de 75 (setenta e cinco) indivíduos foram avaliados (26 reconstruções feixe duplo, 22 reconstruções feixe simples, 27 indivíduos sem lesão do LCA que formaram um grupo controle). Utilizando um sistema de análise do movimento humano, constituído por 4 câmeras para a análise do movimento, os indivíduos foram avaliados em três tarefas de demandas distintas. Utilizou-se a técnica TSACCAST para o cálculo da rotação interna e externa da tíbia. A média da amplitude de rotação tibial, máximo de rotação interna e externa, foi avaliada para cada joelho em cada um dos três grupos. A avaliação clínica destes pacientes foi realizada utilizando-se questionários subjetivo e objetivo (IKDC), assim como artrometria manual. Estas avaliações revelaram que ambos os grupos operados eram semelhantes no que se refere ao resultado clínico pós-operatório. A avaliação da amplitude de rotação tibial, máximo de rotação interna e externa, demonstrou que o joelho operado era semelhante ao joelho não operado e aos joelhos do grupo controle. Também não se verificou diferença significativa nos valores de amplitude de rotação tibial, máximo de rotação interna e externa, quando se comparou o grupo FS ao grupo FD. Desta forma, concluímos que a reconstrução do LCA com a técnica de FS e com a técnica de FD são similares no que se refere ao restabelecimento do controle da rotação da tíbia / In an attempt to better restore the normal function of the two ACL bundles, the ACL reconstruction with two bundles has been proposed. However, the superiority of the double-bundle technique has not been clearly demonstrated in the clinical setting. The purpose of this study was to compare the tibial rotational range, maximal internal and external rotation and ground reaction force of anatomical double-bundle anterior cruciate ligament reconstructed knees with single-bundle anterior cruciate ligament reconstructed knees during three different demanding tasks. A total of 75 subjects, (26 with double-bundle anterior cruciate ligament reconstruction, 22 with single-bundle anterior cruciate ligament reconstruction, and 27 healthy control individuals) were evaluated in this study. Using a 4-camera motion analysis system, motion subjects were recorded performing during three different tasks. Using the CAST technique, the internal-external tibial rotation of both knees was calculated. The mean tibial rotational range, maximum internal and external rotation, for each knee, was evaluated for the 3 groups (double-bundle group, single-bundle group, and control group). Clinical assessment, including objective and subjective IKDC scores, and knee arthrometric measurement, revealed restoration of the reconstructed knee stability with no differences between the two anterior cruciate ligament reconstruction groups. The results demonstrated that both groups resulted in tibial rotation range values that were similar to those in the non-injured knees and those in the healthy controls. There were also no significant differences in tibial rotational range, maximal internal and external rotation and ground reaction force between the DB group and the SB group. Therefore, anatomical double-bundle and single-bundle reconstruction are able to restore normal tibial rotation

Introduction: The Anterior Cruciate ligament (ACL) is one of the most important ligaments in the knee providing joint stability. Rupture of ACL is the most common sports injury. About half of the patients undergo surgical reconstruction. The Orthopaedic clinic in Region Örebro county underwent a reorganization in 2016. Aim: The aim of this study was to evaluate the two-year risk of re-arthroscopy in the same knee after primary ACL-reconstruction. Material and Methods: A retrospective cohort study. All patients from 1st January 2005 until 31st December 2017 with primary ACL reconstruction in Region Örebro county were included. Data was collected from medical records and The Swedish National Anterior Cruciate Ligament Register. Results: 431 patients were included. The total risk of re-arthroscopy was 13.0%. Meniscal surgeries and age did not affect the outcome. Fixation method in femur and tibia affected the outcome, as did choice of graft. There was a small numerical difference before (13.4%) vs after (12.1%) the reorganization, but it was not statistically significant either unadjusted or adjusted for age and meniscal surgeries (p=0.721). Conclusions: Our study indicates that choice of graft and fixation method in femur and tibia affect the re-arthroscopy rate. Regarding graft, the semitendinosus tendon alone was the better option, and for fixation both for femur and tibia it seems like Tightrope was the best option and screw the worst. The reorganization did not affect the outcome but might have other benefits.

Osteoarthritis (OA) of the knee, a musculoskeletal disease characterized by degenerations in multiple joint tissues including the articular cartilage and subchondral bone, is a major clinical challenge worldwide that currently has no cure. Traumatic knee injuries such as anterior cruciate ligament (ACL) tear predispose subjects to early onset of post-traumatic OA (PTOA), necessitating the development of effective disease modifying therapies as total knee replacement surgeries have a limited lifetime. Significant knowledge gap remains in the pathogenesis of OA, while recent evidence suggests the important role of subchondral bone microstructure and mechanics in OA development. Subchondral bone is composed of the subchondral bone plate, a thin layer of cortical lamella, and the subchondral trabecular bone, composed of individual plate-like and rod-like trabeculae. These trabecular plates and rods determine the microstructure and mechanics of trabecular bone entirely and can be quantitatively analyzed using individual trabecula segmentation (ITS). Recent application of ITS showed that changes in the plate-and-rod microstructure of subchondral trabecular bone precede cartilage damage and are implicated to play a role in disease pathogenesis. Studies presented in this thesis aim to provide a deeper understanding of subchondral bone in knee OA scientifically and clinically, which may ultimately be used to improve diagnosis, prevention and treatment of this prevalent and disabling disease. In the first study, we comprehensively quantified microstructural and tissue biomechanical properties of the subchondral bone and articular cartilage in human knee specimens with advanced OA and control knees without OA. We found reduced tissue modulus in trabecular plates and rods in regions with moderate OA, where cartilage is still intact, that persisted in severe OA regions, where cartilage is severely damaged. These observations suggest that tissue biomechanical changes in the subchondral trabecular bone may precede cartilage damage in OA development. Furthermore, we found strong correlations between structural and mechanical parameters of the cartilage and subchondral bone in CT knees, suggesting cross-talk at the tissue level. This coupling persisted in moderate OA regions but disappeared in severe OA regions, suggesting that loss of tissue crosstalk may be an additional indicator of disease progression. In the second study, we quantified subchondral bone microstructural changes after ACL tear in vivo in human subjects using the second-generation high resolution peripheral quantitative computed tomography (HR-pQCT). We examined short-term longitudinal changes during the acute phase (~18 days to ~141 days) after injury, as well as long-term adaptations (~5 years post injury) in the injured knee relative to the contralateral knee in a cross-sectional cohort. We found subchondral bone loss within 1 month from injury that primarily targeted trabecular rods, especially at the distal femur. We also found increased spatial heterogeneity in subchondral trabecular microstructure within the injured knees compared to the contralateral knees in the long-term after injury. These findings indicate that ACL tear results in both short-term and long-term microstructural adaptations in the subchondral bone. ITS based on HR-pQCT knee scans may be a valuable tool to monitor disease progression in vivo. Finally, we quantified subchondral bone microstructural changes after ACL-transection in a canine model of PTOA and investigated the effects of bisphosphonate and NSAID treatment on subchondral bone changes and OA progression. Studies were conducted in skeletally-mature and juvenile animals to investigate the effect of injury age. We found that subchondral bone adaptations after surgery and treatment effects depended on skeletal maturity of animals. In mature animals, changes in the microstructure of trabecular plates and rods occurred 1-month post-op and persisted until 8-months post-op. Bisphosphonate treatment attenuated these microstructural changes and cartilage degeneration while NSAID treatment did not. In juvenile animals that have not reached skeletal maturity, transient changes in trabecular plate and rod microstructure occurred at 3-months post-op but disappeared by 9-months post-op. Neither bisphosphonate nor NSAID treatment attenuated bone microstructural changes or cartilage damages. These findings suggest that age and skeletal maturity at time of injury may need to be considered as additional factors in studying PTOA progression and developing preventative treatments. Taken together, these studies highlight the importance of microstructural and tissue biomechanical changes of subchondral bone in the development of OA. In vivo quantification of subchondral bone using advanced imaging modalities enable longitudinal monitoring of disease progression. Therapeutic agents targeting subchondral bone changes after traumatic injury may be effective preventative strategies for PTOA.