A grande casuística relacionada à afecção ortopédica denominada ruptura do ligamento cruzado cranial na articulação fêmoro tíbio patelar canina tem gerado diversos estudos avaliando a biomecânica articular, fatores extrínsecos ao paciente e características metabólicas que poderiam influenciar na predisposição e no prognóstico dos pacientes acometidos por esta afecção. As dificuldades em identificar os diferentes níveis de instabilidade articular durante o diagnóstico e de estabilidade após o tratamento proposto, seja cirúrgico ou conservativo, provocou o desenvolvimento de diversas técnicas visando um melhor diagnóstico e estabilização articular pós operatória. Apesar da ampla variedade de técnicas cirúrgicas atualmente descritas para a insuficiência do ligamento cruzado cranial (LCC) em cães o tratamento ideal para esta freqüente condição ortopédica permanece indeterminado. Foram avaliados através da termografia infravermelha 30 pacientes caninos acima de 20 quilos sendo divididos em três grupos, o primeiro composto por dez animais hígidos onde foram analisados termograficamente os joelhos bilaterais a fim de padronizar valores térmicos de joelhos caninos normais, o segundo grupo composto por dez pacientes diagnosticados com instabilidade da articulação fêmoro tíbio patelar unilateral que foram submetidos a técnica cirúrgica de TTA para estabilização articular e o terceiro grupo composto por dez animais com diagnóstico de instabilidade da articulação fêmoro tíbio patelar unilateral que foram submetidos a técnica cirúrgica de TPLO para estabilização articular. Os grupos TTA e TPLO foram avaliados termograficamente em período pré operatório e nos momentos 30, 60 e 90 dias de pós operatório. Aos 30 dias de pós operatório houve diferença estatística com o grupo TPLO obtendo valores superiores ao grupo TTA. No período de 60 e 90 dias, não encontramos diferenças estatisticamente significantes nos valores comparativos dos membros operados em relação ao contralateral hígido podendo indicar que as duas técnicas cirúrgicas são capazes de trazer a articulação operada a uma condição de normalidade do ponto de vista termográfico. / The large number of cases related to the orthopedic condition called cranial cruciate ligament rupture in dogs has generated several studies evaluating the joint biomechanics, metabolic and environment characteristics that could influence the susceptibility and prognosis of patients affected by this condition. The difficulties in identifying the different levels of joint instability during diagnosis and joint stability after surgical or conservative treatment led to the development of several surgical techniques aiming a better diagnosis and joint stabilization. Despite the wide variety of surgical techniques currently described for the insufficiency of the cranial cruciate ligament (CCL) in dogs the ideal treatment for this common orthopedic condition remains uncertain. We evaluated using infrared thermography 30 canine patients over 20 kg. They were separated into three groups: the first group were consisted of ten healthy dogs, where we evaluated thermographycally their bilateral stifle in order to acquire thermal values of normal canine knees, the second group had ten patients diagnosed with instability of one stifle and were operated using the surgical technique called TTA and the third group were consisted of ten animals with a diagnosis of instability of unilateral stifle who underwent surgical procedure using the surgical technique called TPLO. The TTA and TPLO groups were evaluated thermographycally before surgery and at times 30, 60 and 90 days postoperatively. At 30 days evaluation we found significant differences between the TPLO and the TTA groups. At 60 and 90 days evaluation there were no significant differences between the operated limb in both groups and their contralateral not affected stifle. This results may indicate that both surgical techniques can bring the stifle back to normal thermographic parameters.

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The anterior cruciate ligament (ACL) plays an important role in knee joint stability, and unfortunately is one of the most commonly injured knee joint structures. The muscles surrounding the knee are also critical for stabilising the knee joint and their activations are altered following ACL injury. Despite the fact that ACL injuries are up to 8 times more likely to occur in females compared to males, there is limited research evaluating the effects of sex on how ACL-deficient individuals adjust neuromuscular control strategies during varying loading conditions. In order to have clinicians implement optimal rehabilitation strategies for ACL-deficient males and females, it is crucial to understand the adaptive functional strategies that are taking place once an ACL injury has occurred. The purpose of this thesis was therefore to provide objective and quantitative measurements describing the functional roles of muscles surrounding the knee. This was accomplished and outlined in this thesis through two chapters in manuscript format and summarised below. i) Sex and ACL-deficiency influence functional muscle roles during an isometric, weight-bearing, force-generation task First, the functional roles of muscles were quantified through the assessment of muscle activations during a series of multi-directional force-production tasks in ACL-deficient males and females while weight bearing. A highly controlled, isometric, force-matching task, whereby participants modulated ground reaction forces in various combinations of sagittal and frontal plane loads was used to quantify force-generation strategies (muscle activations and functional role) of the knee joint. Mean activation magnitudes and profile patterns from 10 muscles in the lower extremity (rectus femoris, vastus lateralis, vastus medialis, biceps femoris, semitendinosus, lateral gastrocnemius, medial gastrocnemius, tensor fascia latae, adductor muscle group, and gluteus medius) were recorded using wireless electromyography (EMG) sensors. Their activations were quantified with an orientation analysis to determine if differences in functional muscle roles existed between four groups; healthy female controls, healthy male controls, ACL-deficient females, and ACL-deficient males. Overall, different functional muscle roles were found between groups. Healthy male controls activated their muscles the most specifically; females with ACL-deficiency activated their muscles the least specifically, while healthy female controls and males with ACL-deficiency shared similar functional muscle roles. This suggests that there was a specificity hierarchy in the ability, or efficiency, to modulate the activation of muscles about the knee joint when exposed to various directional loading conditions. ii) Associations between subjective measures of knee dysfunction and measures of ground reaction forces in ACL-deficient males and females Correlational relationships were evaluated between perceived knee joint function and functional capacity of the knee joint. These relationships were calculated between patient reported outcome measures (PROM) from commonly used knee assessment scoring scales maximal generated forces in the sagittal and frontal planes. Both ACL-deficient groups had significantly lower perceived knee joint function compared to healthy controls. A trend towards significance was observed in the ability to generate maximum forces in the sagittal and frontal planes, with ACL-deficient females generating smaller maximal posterior GRFs compared to healthy females. Only two statistically significant correlations (both for ACL-deficient females) were found between maximal medial GRFs and patient reported outcome measures from the Lysholm and Tegner scoring scales. This indicates that there may be a discrepancy in the sensitivity of subjective outcome measures between sexes and their corresponding ability to generate maximum GRFs. In conclusion, sex differences exist in subjective outcome measures and the functional strategy of neuromuscular control of the knee joint both before and after ACL-injury. The results of this thesis indicate the need for sex-specific tailoring of rehabilitation programs, thus providing an opportunity to improve the success rate of rehabilitation following ACL-injury. Moreover, sensitivity of subjective outcome measures and their relation to simple, practical, functional tasks between sexes warrants further investigations.

As an exploratory, developmental injury intervention study, this research investigated the efficacy of providing psychological intervention in the form of relaxation and guided imagery to a group of orthopedic patients recovering from major knee surgery. Utilizing a prospective, experimental research design with 30 subjects randomly assigned to either an intervention, placebo, or control group, this study employed physiological as well as psychological outcome measures. Intervention consisted of 10 individual mental practice sessions for intervention group members as an adjunct to physical therapy. Content of these sessions was intentionally designed to facilitate physiotherapy goals. Imagery protocols with which to deliver these standardized sessions were also designed to directly parallel established physical rehabilitation protocols. Placebo group participants were exposed to nonspecific intervention factors of attention and support, while control group members completed their physical therapy as usual. Results of this study revealed that for this sample of anterior cruciate ligament (ACL) orthopedic patients, psychological injury intervention in the form of relaxation and guided imagery contributed to statistically significant better physical and psychological outcomes. Strength and extension improvement, as well as reduction in state, trait, and reinjury anxiety, were superior for the intervention group as compared to placebo and control groups from preintervention (2 weeks postsurgery) to post-intervention (24 weeks postsurgery). Other benefits of the intervention, according to subject self-report, included pain and stress management, empowerment, control of recovery, and overall body wellness . Implications of these research findings are discussed, as well as suggestions offered for subsequent injury intervention research.

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Little research has been done to validate the biomechanical principles of tibial tuberosity advancement (TTA) throughout stance. The present study evaluates the effects of TTA on kinematics of the cranial cruciate (CrCL) deficient stifle during early, middle, and late stance. Cadaveric pelvic limbs were evaluated for the effects of TTA on kinematics under a load equivalent to 30% bodyweight and under the following treatment conditions: intact CrCL, CrCL deficient, TTA-treated, and TTA treated + meniscal release. Electromagnetic tracking sensors were used to determine tibial subluxation and rotation relative to the femur. Transection of the CrCL resulted in significant cranial tibial subluxation during early, middle, and late stance and significant internal rotation during early and middle stance. TTA normalized tibial subluxation in early, middle, and late stance but was unsuccessful in normalizing axial rotation in middle stance. Meniscal release had no effect on cranial/caudal or rotational displacement when performed following TTA.

Despite the well-researched impact of ACL injuries, both acutely and longitudinally, and even though adolescent females have the highest risk of sustaining an ACL injury, there is surprisingly very little biomechanical research conducted on adolescent populations after an ACL rupture has taken place. The increasing rates of ACL injuries and re-injury among adolescents demonstrates a need for improved rehabilitation and return-to-activity (RTA) guidelines that are age/maturity- and sex-appropriate. To accomplish this, the first step is to describe this population alongside a non-injured activity-, maturity- and sex-matched population. Therefore, the overall purpose of this Doctoral thesis was to provide evidence to support the creation of return-to-activity guidelines for adolescent patients with ACL injuries. The findings of this thesis, briefly outlined below, can directly contribute to improving clinical and rehabilitation management of ACL injuries among adolescent males and females. First, a systematic review was performed to synthesize sex differences in muscle activation patterns in movements associated with ACL injuries in both adult and adolescent populations. Ultimately, 30 articles were included in the review with a wide range of inconsistent findings. In brief, females demonstrated higher pre- and post-landing activation of the quadriceps and lower activation of the hamstrings in 15 of 27 studies. Females also had higher quadriceps-to-hamstring co-contraction ratios during pre- and post-landing phases compared to their male counterparts in 4 of 9 studies. What's more concerning was the identification of only five research articles that evaluated muscle activations in adolescent or younger cohorts, further emphasising the importance of addressing this gap in literature. The second article of this thesis explored metrics used to evaluate knee joint function that are often a part of rehabilitation guidelines, such as limb symmetry indices (LSI) during single limb hopping and strength tasks. To date, no evidence exists to support or refute the use of these measures in an adolescent population. Therefore, we sought to investigate LSIs and knee joint function among adolescent males and females with and without ACL-injuries during single-limb assessments. A total of 141 participants were recruited and evaluated during a series of maximum voluntary tasks; isometric knee extension and flexion, and single-limb hopping tasks (anterior-hops, lateral-hops, 6m timed-hops, cross-hops, and triple-hops). In brief, females and males with ACL injuries had lower performance metrics compared to their matched controls, however, the differences were not the same within each sex. Females displayed deficits in all tasks, whereas males with and without ACL injuries were only different in the anterior-hop, triple-hop, and knee extension tasks. The final two articles of this thesis are complimentary as they both explored knee stabilisation strategies during countermovement jumps (CMJs) and side-cutting tasks. However, Article 3 included only adolescent males and females without ACL injuries to identify the influence of sex and limb-dominance on knee stabilisation strategies, whereas Article 4 included the same uninjured cohorts but compared with matched groups of males and females with ACL injuries. In both studies, surface electromyography and full-body kinematics were captured during CMJs and side-cutting. Knee stabilisation strategies were evaluated using co-activation indices (CIs), full muscle waveforms, knee joint flexion stiffness (KJFS) and knee joint sagittal and frontal excursions (KJSE and KJFE, respectively). In Article 3, sex differences were observed in CIs, with females having higher medial CIs in the non-dominant limb in both CMJs and side-cuts, and higher total CIs in the non-dominant limb during side-cuts. Between-limb differences were present in both sexes. Females had higher total CI in their non-dominant limb in CMJs and higher frontal KJE in their non-dominant limb during the stance phase of side-cuts. Males had higher medial CIs in their dominant limb in CMJs and higher sagittal KJE in their non-dominant limb during the preparatory and landing phases of CMJs. No significant sex or limb differences were identified in individual muscle activations or KJFS. Based on these findings, males and females were treated statistically independent when evaluating the effect of ACL-injury in Article 4. Interestingly, when comparing groups, only one significant effect of injury was observed in knee stability metrics; males with ACL injuries had significantly higher vastus medialis activity during the preparatory phase of the CMJ compared to their uninjured counterparts. There were no other significant differences in either task. Despite the importance of ACL injury prevention in adolescents, the evidence on sex difference in muscle activation patterns in this population is still scarce. The results of this Doctoral thesis indicate that males and females in adolescent populations have differences in knee stabilisation strategies and overall knee joint function. These findings further support the need for additional research considering risk factors such as, age/maturity-, sex-, and limb-dominance. This research will contribute to the tailoring of rehabilitation programs, thus providing an opportunity to improve the success rate of rehabilitation following ACL-injury among adolescents.

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