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Robotic assisted partial knee arthroplasty (PKA) has gained in popularity as a treatment for end stage knee osteoarthritis (OA) that involves only one or two compartments of the knee over total knee arthroplasty (TKA). PKA surgeries are known for their less invasive and more precise treatment of medial or lateral compartmental (+/- patellofemoral) arthritis, improved postoperative range of motion, greater ligament and bone preservation, and a more natural gait. The Robotic Arm Interactive Orthopedic MAKO Stryker (RIO; MAKO Stryker, Fort Lauderdale, Florida) Robot has significantly improved PKA implant alignment by providing real-time feedback during surgery and improving three-dimensional implant placement accuracy. To assess kinematic differences between robotic assisted PKA and manual technique TKA, a 14-camera optoelectronic motion capture system (Optitrack, NaturalPoint, Corvallis, OR USA) was designed and installed in a hospital hallway to collect patient gait outcomes directly after clinic appointments. This thesis investigates the feasibility and validity results from setting up a motion capture system and its associated reliability when using it in a high traffic clinical environment. The first objective of this thesis was to investigate a total of 26 patients (14 TKA, 12 PKA) that underwent a kinematic gait assessment at 4-time points; preoperatively, and postoperatively (3,6,12 months). At 3 and 6 months postoperatively, the TKA group had improved knee flexion range of motion (ROM) during walking compared to the PKA group. This result was statistically significant (3-month p value =0.042, 6-month p value= 0.048). At 6 months, changes in the knee adduction/abduction angles were also significantly different (p value= 0.023), showing less knee ROM in the frontal plane after a PKA comparable to healthy controls. Despite differences in improvements in joint kinematics during walking between the two groups, these factors did not necessarily correlate with better perceived patient reported outcomes (PROMs). The results obtained from this pilot study display initial feasibility and suggest further research is required on a larger sample size to confirm if PKA surgeries are superior to TKA surgeries in terms of gait function. In conclusion, a repeatable, instrumented gait analysis was setup in a busy orthopedic hallway where reliable data can be collected. / Thesis / Master of Applied Science (MASc) / Robotic assisted partial knee replacements have been gaining popularity in recent years due to the perceived benefits over a total knee replacement such as preserving more bone, faster recovery, and improved walking outcomes. A partial knee replacement can either replace one or both compartments of the knee joint, depending on the level of arthritis in the patient's knee. This thesis investigated the differences in walking ability before and after surgery using a specialized system installed in the hospital to collect data during regularly scheduled appointments. Patients in this study either received a partial knee replacement with the help of a surgical robot, or a regular total knee replacement. The results showed that there is a significant difference in how much the knee moves during walking between patients who had the robot surgery and those who had the usual surgery. However, the patient’s experience and their perception of how well they were doing after surgery were not different between the two surgeries. This study provided valuable insight into the current surgical treatments available for knee arthritis.

Knee osteoarthritis (OA) is a progressive disease that ultimately requires patients to receive a total knee arthroplasty (TKA) to replace the damaged structures within the knee with an artificial joint. Surgeons have many options when selecting an appropriate implant. Patients want a TKA that feels 'normal' and allows them to perform most activities without pain, stiffness, and other residual symptoms. However, 20% of patients remain unsatisfied with their surgery, regardless. This thesis aimed to examine the effect of implant selection during TKA on knee biomechanical function during various ADLs. Several gaps were identified within the review of literature: 1) patient-reported outcome measures cannot differentiate between medial ball and socket (MBS) and posterior stabilized (PS) implants, 2) most biomechanical studies were performed only in postoperative patients, and 3) studies that compared MBS and PS implants were primarily focused on level walking conditions, and overlooked tasks that placed more demand on the knee joint. Twenty-eight individuals with severe knee OA were randomized to receive either an MBS (n=14) or PS implant. They completed a biomechanical assessment within one month and one year after TKA and were compared to 14 controls of similar age, sex, and body mass index. They performed a variety of tasks which explored three main areas: 1) examine the alterations in gait variability among individuals with OA following a TKA procedure using either a PS or MBS implant; 2) enhance the understanding of the post-operative effects of TKA with either MBS and PS implants on knee biomechanics and muscle activities during level walking, as well as more demanding tasks such as descending a ramp or staircase; 3) simulate the dynamic knee joint loads in post-operative TKA patients with either PS or MBS implants during closed-chain, bilateral tasks such as sit-to-stand. Initially, a series of studies were performed to develop a new test called waveform-level variance inequality test (eqvartest), which had not been previously utilized in the literature. This test was used to identify discrepancies in gait variability pre and post-TKA in the gait cycle. Following TKA, patients showed decreased variability in knee moment and power at single-limb support. Neither the MBS nor PS implant provided the same level of variability as the control group, demonstrating reduced knee joint stability. The MBS group had a gait pattern closer to the control group during level walking, whereas the PS group walked with a stiffer knee. However, during more demanding ADLs, the differences were less apparent. During ramp descent, knee joint stability issues became prominent as MBS and PS groups adopted a 'cautious gait pattern,' widening their base of support and stiffening their knee to reduce loading. During stair descent, the MBS implant provided increased stability as it required less muscle activity than the PS, requiring greater hamstring muscle activation. During sit-to-stand, MBS and PS groups favoured their non-operated knee as they had reduced total vertical, medial, and lateral KCF on their operated knee compared to their non-operated side. This may be due to compensatory strategies developed through the progression of knee OA and may increase the risk of developing knee OA on the non-operated limb. The outcomes of this thesis can assist clinicians in selecting the most appropriate implant for their patients and guide them in designing rehabilitation programs that can enhance patient function following TKA.

Mechanical factors have been cited as a primary cause of total knee replacement failure. A hypothesis has been formulated stating that the introduction of a compliant interface into a total knee prosthesis would moderate excessive stresses and strains, thereby, extending joint life. A biocompatable elastomer developed by the Dow Corning Corporation was selected for mechanical evaluation as a cushioning material. Force-strain, impact, and fatigue tests were conducted on several specially designed and fabricated elastomer test shapes. Test results demonstrate that a suitably stiff and dynamically responsive elastomer cushion can be designed to handle repeated physiological knee joint loads. Physiological impacts with cadaver tibias demonstrated significant shock reduction benefits, including peak force reductions of up to 70%, with the addition of different elastomer shapes. Compressive fatigue evaluation of elastomer samples was inconclusive owing to extensive sample wear. As a result configurations or applications where the elastomer can move relative to a rigid surface are not recommended. A new, mechanically contained elastomer shape was designed and tested which greatly reduced wear. Bonding of this new shape to prosthetic joint materials is recommended for further experimental evaluation. / Thesis / Master of Engineering (ME)

It has been noticed that the need for total knee replacement surgery is increasing for Asian region. A total knee replacement is a permanent surgical solution for a patient having debilitating pain in knee joint suffering from arthritis. In this surgery, knee joint is replaced with components made up of bio-compatible materials after which the patient can resume the normal day to day activities. Western population has bigger build compared to Asian population. Most of the total knee replacement prosthesis are designed for western population. When these total knee prosthesis are used for Asian population, they cause a mismatch leading to various clinical complications such as reduced range of motion and pain. The studies have been limited to clinical complications caused by the mismatch. To address this limitation, current study is aimed to find the mechanical implications such as stress distribution, maximum stresses, maximum displacements etc., caused by mismatch of total knee replacement components with knee. A surgeon selects total knee components for a patient based on some critical dimensions of femur and tibia bone of knee. In addition, a method to accurately calculate these dimensions of the femur and tibia bone of a real knee was developed in the current study. This method calculated the points of curvature greater than a threshold (decided based on the radius of the curvature) found out using the formula of curvature. Further, the highest point was calculated based on maximum height from a line drawn between initial and final point within the captured points, also the extreme points were calculated based on the sign change in slope of points within the captured points, giving multiple points on the boundary of bones extracted in an MRI image of a patient. The distance between two selected farthest points, out of these points, in specific direction was the basis for selection of the TKR components. Total knee replacement components were modeled in Geomatics Studio 12 software, bones were modeled in Rhinoceros 5 software, assembly of bones and total knee replacements components was done in Solid works 2013 software, the finite element model of the assembly was developed in Hyper mesh 11 software and, the stress analysis and post processing was done in ABAQUS 6.13 software. A static, implicit non linear analysis was performed. Simulations were performed for two conditions: at standing (0o of flexion) and at hyper-flexed (120o of flexion). In order to figure out if there were any mechanical implications of mismatch, the full model of assembly consisting of femur, tibia and fibula bones assembled with total knee replacement components, and the reduced model consisting of only total knee replacement components were simulated separately, results of which have been discussed in the current thesis. In this work, the effect of change of length of ligaments at 120o of flexion in detail was also studied. This study brought out various outcomes of contact mechanics and kinematics between the components of total knee replacement prosthesis.

published_or_final_version / Medical Sciences / Master / Master of Medical Sciences

Unicompartmental knee replacement (UKR) is the principal alternative to total knee replacement (TKR) in the treatment of end-stage knee osteoarthritis. It involves less tissue resection, resulting in lower rates of morbidity and faster recoveries compared to TKR. However, UKR has a significantly higher revision rate compared to TKR. As a result, whilst over a third of patients are eligible for UKR, only around 8% receive it. A comprehensive comparison of matched patients undergoing TKR and UKR was undertaken using a large dataset from the National Joint Registry for England and Wales (NJR). Failure rates (revision, reoperation, complications and mortality), length of stay and patient-reported outcomes (PROMs) were studied. Whilst patients undergoing TKR had lower reoperation and revision rates, they had higher rates of morbidity and mortality, longer hospital stays, and inferior PROMs compared to UKR. The main reason for revision in UKR was loosening. In view of the high revision rate in UKR, NJR data was studied to identify modifiable risk factors for failure in UKR. Important patient factors were identified including age, gender and pre-operative function. Surgeons with a higher UKR caseload had significantly lower revision rates and superior patient-reported outcomes. Increasing usage (offering UKR to a greater proportion of knee replacement patients) appears to be a viable method of increasing caseload and therefore of improving results. Surgeons with optimal usage (around 50% of patients, using appropriate implants) achieved revision/reoperation rates similar to matched patients undergoing TKR. Two clinical studies were conducted to establish whether the use of cementless fixation would improve fixation and reduce the revision rate of UKR. Cementless UKR was demonstrated to be safe and reliable, with PROMs similar or superior to those demonstrated in cemented UKR. Patients with suboptimal cementless fixation were examined and pre-disposing technical factors were identified. Finally, using NJR data, the effect of the introduction of cementless UKR on overall outcomes was examined. The number of cementless cases was small, and no significant effect on implant survival was demonstrated. However, patients undergoing cementless UKR demonstrated superior PROMs. These studies demonstrate that UKR has numerous advantages over TKR in terms of morbidity, mortality and PROMs. If surgeons perform high volumes of UKR (achievable by increasing their UKR usage), these advantages can be attained without the large difference in revision rates previously demonstrated. Cementless UKR is safe and provides superior fixation and outcomes in the hands of high-volume surgeons. Further work is needed to quantify the revision rate of cementless UKR, and to assess its results in the hands of less experienced surgeons.

Submitted by Ana Lúcia Torres (bfmhuap@gmail.com) on 2017-10-04T13:09:23Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Tese Ricardo Bastos.pdf: 1699294 bytes, checksum: 9f66927af352d688894773afaee06cdd (MD5) / Approved for entry into archive by Ana Lúcia Torres (bfmhuap@gmail.com) on 2017-10-04T13:09:37Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Tese Ricardo Bastos.pdf: 1699294 bytes, checksum: 9f66927af352d688894773afaee06cdd (MD5) / Made available in DSpace on 2017-10-04T13:09:37Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Tese Ricardo Bastos.pdf: 1699294 bytes, checksum: 9f66927af352d688894773afaee06cdd (MD5) Previous issue date: 2013 / Universidade Federal Fluminense / Osteotomia tibial alta (OTA) é um recurso frequentemente utilizado para o tratamento da artrose de joelho em pacientes jovens com o objetivo de retardar a necessidade de uma artroplastia total de joelho (ATJ). O objetivo do estudo foi de avaliar a influência da técnica de OTA (adição ou subtração) no resultado final da ATJ e comparar a sobrevida das cirurgias de osteotomias com a idade dos pacientes no momento do procedimento Nossa hipótese é que o alinhamento do membro, seguimento clínico dos pacientes e taxa de complicações sejam iguais em pacientes submetidos a ATJ após OTA de adição e subtração além de que as osteotomias de subtração apresentem uma maior duração até a ne-cessidade de realização da ATJ. Supomos também que a idade dos pacientes na época das osteotomias tenha uma relação linear positiva com a sobrevida desta cirurgia. Cento e quarenta e uma ATJs com antecedente de cirurgia de OTA (24 osteotomias de adição e 117 de subtração) foram selecionadas. Fatores intra-operatórios, resultados clínicos e alinhamento do membro foram analisados. A duração (sobrevida) das 2 diferentes técnicas de osteotomia até a realização da ATJ, assim como o impacto da idade dos pacientes na duração das duas técnicas desta cirurgia, também foram observados. Não foram observadas diferenças significativas nos escores IKS quando comparadas as duas técnicas cirúrgicas. Foi observada uma tendência a maior necessidade de uma osteo-tomia da tuberosidade anterior da tíbia (TAT) no grupo das osteotomias de subtração. Foi encontrada uma maior necessidade de liberação de partes moles (release) medial mais extensa no grupo das osteotomias de adição e uma liberação de partes moles lateral mais importante no grupo das osteotomias de subtração. Não foram encontradas diferenças no tempo de is-quemia, taxas de complicação ou no eixo mecânico final do membro inferior entre os dois grupos. O alinhamento radiográfico, resultados funcionais, objetivos e taxas de complicações são iguais em pacientes que se submetem a uma ATJ após a realização de uma OTA de adição e de subtração. A cirurgia de osteotomia tibial alta de subtração parece apresentar uma longe-vidade (sobrevida) maior até a necessidade da realização de uma artroplastia total de joelho quando comparada a uma osteotomia tibial de adição. Existe uma relação positiva e significa-tiva entre a idade do paciente na época da realização da osteotomia e a duração dessa cirurgia até a necessidade de uma artroplastia / High tibial osteotomy (HTO) is frequently used to treat varus osteoarthritis in younger patients with the goal of delaying the need for total knee arthroplasty (TKA). While it has been reported that the results of TKA following HTO are worse than those in patients without prior knee surgery, the influence of osteotomy technique (medial opening-wedge versus lat-eral closing-wedge) has not been explored. The purpose of this study was to evaluate the in-fluence of HTO technique on the performance and results of TKA. Our hypothesis is that the limb alignment, clinical follow-up and rate of complications are equal in patients undergoing TKA after closing-wedge and opening-wedge osteotomies and that the closing-wedge osteotomies have a higher survival rate when compared to open-ing- wedge osteotomies. We also suppose that younger patients at the time of the osteotomies have a longer delay until the need of performing a TKA. A hundred and one TKA’s performed in 118 patients with prior HTO (24 opening wedge and 117 closing wedge) were reviewed at a mean follow-up of 2 years. Reviewed data included intra-operative factors (tourniquet time, the need for additional exposure, and intra-operative complications), clinical results (International Knee Score (IKS)), and radiographic assessment of limb alignment. There was no significant difference in IKS scores based on osteotomy technique. There was a trend toward an increased need for tibial tubercle osteotomy in the closing-wedge group. There was an increased need for extensive medial release in the opening-wedge group and extensive lateral release in the closing-wedge group. No differences in tourniquet time, complication rates, or hip-knee-ankle angle were noted between the two groups. Radiographic limb alignment, patient-reported outcomes, and complication rates are equal in patients undergoing TKA after opening and closing wedge HTO. Closing-wedge high tibial osteotomy has a longer survival until the necessity of a total knee arthroplasty when compared to an opening-wedge high tibial osteotomy. There is a posi-tive and significant relationship between the patient's age at the time of the osteotomy and the survival of this surgery

The results of total knee arthroplasty are inferior in younger patients. The challenge today is therefore to develop designs and concepts that will last at least 25 years. This thesis has evaluated the fixation to bone of modern designs of knee prostheses uring RSA analysis. Coating implant surfaces with hydroxy-apatite have proven to enhance fixation to bone. Addition of screws for fixation of the tibial component enhances the fixation, but has negative side effects such as osteolysis around the screws, in turn leading to a higher risk of component loosening. The magnitude and pattern of migration was studied in a randomized study of uncemented tibial implants coated with hydroxy-apatite with and without additional screw fixation in patients younger than 65 years. The uncemented implants migrated initially more than the cemented implants that constituted the control group. Both uncemented groups stabilized at 3 monthes with no further migration, while the cemented implants showed a continuous migration up to the 2 year follow-up, indicating continuous bone resorption at the implant-bone interface, a fact that might lead to an increased risk of late implant loosening. This may not be a problem in older patients, but may have consequences for long-term fixation in younger patients. There was no difference between the two uncemented groups indicating that screws do not improve fixation. Hydroxy-apatite coated knee implants might be well suited for younger patients. Mobile bearing total knee arthroplasty theoretically uncouples the forces at the implant-bone interface, thus improving fixation of the implant to bone. The magnitude and pattern of migration of a cemented mobile bearing knee arthroplasty and a fixed bearing total knee arthroplasty was compared in a randomized study. The results showed that mobile bearings did not improve fixation. Trabecular metal, a new material recently introduced for total knee arthroplasty, has several theoretical advantages. Trabecular metal tibial implants were evaluated in a randomized study in patients younger than 60 years. The implants displayed the typical migration pattern for uncemented implants with greater migration initially followed by early stabilization. The majority of the trabecular metal implants subsided into the bone with no lift-off. Lift-off has the potential of exposing the interface to joint fluid with the potential risk of bone resorption and late loosening, and is commonly seen in metal-backed implants. The finding of absence of lift-off is regarded beneficial for uncemented fixation. Trabecular metal tibial implants might be suited for younger patients. The optimal mode of fixation of the femoral component is yet to be established. Comparing cemented femoral components with uncemented femoral components in a randomized study in patients younger than 60 years revealed no differences of the magnitude or the pattern of migration. Uncemented femoral component seems equally as good as cemented components in younger patients.

Source: Masters Abstracts International, Volume: 47-06, page: 3565. Adviser: Benjamin Amick. Includes bibliographical references.