Injury, instrumentation, or surgery may change the functional biomechanics of the spine. Spinal fusion, the current surgical treatment of choice, stabilizes the spine by rigid fixation, reducing spinal mobility at the cost of increased stress at adjacent levels. Recently, alternatives to spinal fusion have been investigated. One such alternative is total disc replacements. The current generation of total disc replacements (TDRs) focuses on restoring the quantity of motion. Recent studies indicate that the moment-rotation response and axis of rotation, or quality of motion (QOM), may have important implications in the health of adjacent segments as well as the health of the surrounding tissue of the operative level. This dissertation examines the use of compliant mechanism design theory in the design and analysis of spinal arthroplasty devices. Particularly, compliant mechanism design techniques were used to develop a total disc replacement capable of replicating the normal moment-rotation response and location and path of the helical axis of motion. Closed-form solutions for the device's performance are proposed and a physical prototype was created and evaluated under a modified F1717 and a single-level cadaveric experiment. The results show that the prototype's QOMclosely matched the selected force-deflection response of the specified QOM profile. The use of pseudo-rigid-body modeling to evaluate the effects of various changes on motion at adjacent segments is also investigated. The ability to model biomechanical changes in the spine has traditionally been based on animal models, in vitro testing, and finite element analysis. These techniques, although effective, are costly. As a result, their use is often limited to late in the design process. The pseudo-rigid-body model (PRBM) developed accurately predicted the moment-rotation response of the entire specimen and the relative contribution of each level. Additionally, the PRBM was able to predict changes in relative motion patterns of the specimen due to instrumentation.

Thesis: M.S., Massachusetts Institute of Technology, Department of Mechanical Engineering, 1980 / Bibliography: leaves 216-232. / by Francis Joseph Halcomb, III. / M.S. / M.S. Massachusetts Institute of Technology, Department of Mechanical Engineering

Increased workload on our healthcare system calls for more automation, this too in the pre-operative planning of total knee arthroplasty (TKA) surgery. This should keep in mind however that success in TKA is measured through having proper limb alignment. This thesis project implemented a virtual positioning assessment software that provides an initial position based on its bone and implant inputs with their specific landmarks. Positions can be furtherly adapted and evaluated based on flexion facets, obtaining decreased pre-operative workloads. The software was validated through an analysis comparison of the femur positioning of nine cases with the former used analysis tool of the university Hospital of Ghent. The newly implemented software was concluded to approximate the patients’ pre-operative alignment better for all translational and rotational parameters, except anteroposterior translation and internal/external rotation of the femur.

The purpose of this integrated review of the literature was to explore the postsurgical infection complications commonly occurring in individuals undergoing total knee replacement surgery, and the relationship of co-morbidities, lifestyle choices, and genetics on the risk for complication. A comprehensive search of the literature focusing on the patient surgical site infection and total knee replacement surgery using the Cumulative Index to Nursing and Allied Health Literature (CINAHL) and Medical Literature On-line (MEDLINE). Initial searches revealed 80 results. Upon closer scrutiny, duplicates were removed, as well as those not relevant to infection in total knee arthroplasty. This resulted in a review of 6 articles that fit the inclusion criteria. Inclusion criteria were articles written in the English language and published in scholarly, peer-reviewed, journals from 2009 to present. In addition to published articles, pertinent material from current nursing textbooks was evaluated and chosen to further substantiate the literature results. In cases of knee arthroplasty, diagnoses of obesity and diabetes were discovered to be risk factors for postsurgical infection. The findings of this thesis offer interpretation for nursing practice, research, education, and policy. Implications for nursing research, policy, education and practice are highlighted along with limitations of this integrative review.

Die Möglichkeiten der operativen Rekonstruktion degenerativ veränderter Hüftgelenke sind komplex und vielfältig. Bei den derzeit zur Verfügung stehenden operativen Behandlungsmassnahmen führen die Vor- und Nachteile immer wieder zur Diskussionen und Abwägung der Operationsverfahren. Hierbei stehen sich die rasche postoperative Mobilisierung sowie eine verminderte Rekonvaleszenzzeit mit den diskutierten Nachteilen einer schlechteren Übersichtlichkeit und damit verbundenen Fehlimplantationen gegenüber. Dies und die damit verbundene volkswirtschaftliche Bedeutung sind ein ständiger Ausgangspunkt für das Bemühen den optimalen Zugangsweg zu etablieren. Daher stellte das von Smith-Peterson 1949 publizierte Verfahren einen Meilenstein in der operativen Therapie dar. Hierdurch konnten zum einen die operationstechnischen Vorteile wie auch das volkswirtschaftliche Begehren nach kürzeren postoperativen Verweildauern vereint werden. Die Modifizierung dieses Zugangsweges hat sich bereits in einer großen Anzahl prospektiver Studien als zuverlässiges Rekonstruktionsverfahren etabliert und erfüllt zudem auch die Anforderungen der heutigen Medizin nach ästhetisch schönen Ergebnissen. In der vorliegenden Arbeit wurde eine prospektive Fallstudie des direkten anterioren Zugangs mit einem gesunden Vergleichskollektiv durchgeführt. Mit dem Ziel, die Aktivität ein Jahr postoperativ nach Implantation einer HTEP mit gesunden Probanden zu vergleichen. Von Januar 2009 bis Mai 2011 wurden insgesamt 77 Patienten und 59 Probanden in die Studie aufgenommen. Als Vergleichswerte wurde zum einen die klinische wie auch die radiologische Untersuchung herangezogen. In der klinischen Untersuchung zeigte sich insgesamt ein signifikanter Anstieg der untersuchten Scores im Vergleich mit den präoperativen Ergebnissen bei den Operierten. Im Vergleich zu den Probanden erzielen die Patienten ein Jahr nach HTEP teilweise noch schlechtere Werte in dem Bewegungsumfang und den Aktivitätsniveaus welche mittels der Auswertung des Stepwatches, des TWB und des Arzt-Patienten-Fragebogens erhoben wurden. Die radiologische Bewertung diente zur Feststellung der Positionierung der HTEP. Mit guten Positionierungen durch den direkten anterioren Zugang. Die Bewertung der Funktionalität zwischen den beiden Gruppen erfolgte durch den HHS, XSFMA- D und den Arzt-Patientenfragenbogen. Hierbei konnten ähnliche Ergebnisse, wie bereits oben beschrieben, verzeichnet werden mit guten Werten in der Gruppe der untersuchten Patienten, jedoch einer geringeren Funktionalität im Vergleich zu den Probanden. Die vorliegende Arbeit zeigt, dass der direkte anteriore Zugang die Wiederherstellung eines guten postoperativen Gesundheitszustandes mit erreichen eines hohen postoperativen Aktivitätslevels der Patienten ermöglicht. Ebenso erfüllt dieser Zugangsweg die Anforderungen der heutigen Medizin im Sinne einer schnellen postoperativen Mobilisation. Im Vergleich zu anderen minimal-invasiven Verfahren zeigen sich eine gute Implantierbarkeit, eine gute Positionierung und ein niedriges Komplikationsniveau. Prinzipiell hat der minimal-invasive anteriore Zugang das Potenzial sich als ein Standardverfahren in der operativen Rekonstruktion bei Hüftgelenksersatz zu etablieren, jedoch wäre ein direkter Vergleich mit dem lateralen Zugang erstrebenswert und sollte in weiteren Studien verglichen werden. / Background: The aim of this prospectve study was to evaluate the clinical results one year after total hip arthroplasty performed through a minimally invasive direct anterior approach versus a healthy volunteer group. Methods: 77 patients and 59 probands have been evaltuated applying the Stepwatch activity monitor (SAM), the Harris hip score (HHS), the SF 36, a daliy activity questionnaire (DAQ) and the XSFMA. Results: The average SAM showed significant differences of 5658 steps (patients) compared to 6417 steps (proband) (p=0,011). The same routcome can be seen in the DAQ with 4226 (patients) and 4686 (proband) cycles (p=0,327) respectively. No significant difference occured by using the average HHS reflecting an equal outcome of 90,7 points in the patient group compared to 90.8 points in the proband group (p=0,022). In contrast tot he afore-mentioned HHS, was a significant increase of the XSFMA reported with 10,9 (patients) and 5.0 (proband) (p=0,001). The SF -36 physical component scores were 45.8 (patients) and 50.6 (proband) while the psychometric properties added up to 56.6 (patients) and 55.9 (proband). While the physical component scores (p=0,001) showed a significant difference this couldnt be observed for the psychometric properties (p=0,511). Conclusion: In our study, good results have been obtained after the first year of the total hip arthroplasty, however these are not as beneficial as the outcomes in the healthy volunteer group.

Background. Around 25-45% of elective total joint arthroplasty (TJA) for primary hip and knee osteoarthritis (OA) are of questionable appropriateness. -- Objective. To examine how appropriateness of elective TJA for hip and knee OA is determined. -- Methods and results. Multi-methods studies guided by the Knowledge-To-Action (KTA) framework and the six Hawker appropriateness criteria for TJA. Study 1 was an interpretive descriptive study exploring barriers and facilitators to using the Hawker appropriateness criteria for adults with knee OA. Nine semi-structured interviews with healthcare professionals and 14 with adults with a TKA revealed: a) 15 barriers (including difficulties in using criteria, lack of accessible conservative treatments, unreceptivity to practice change, clinical judgement limited to OA severity and age, patients receiving information after the decision is made); and b) one facilitator (providing research evidence to obtaining healthcare team buy-in). Study 2 was a systematic review identifying and appraising instruments to assess elective TJA appropriateness for adults with hip and knee OA. None of the 55 instruments met all the Hawker appropriateness criteria; the most included criteria were OA impact on quality of life and evidence of OA while the least included were trial of conservative treatments and elements of shared decision-making. There was limited evidence on psychometric properties. Study 3 was an environmental scan of online Canadian resources for adults with hip or knee OA considering TJA and healthcare professionals participating in the decision. The 73 patient resources were understandable for diverse health literacy levels, but only four were patient decisions aids. Thirteen healthcare professional resources typically recognized OA impact on quality of life, evidence of OA, trial of conservative treatments, and did not discuss elements of shared decision-making. -- Conclusion. When determining appropriateness of elective TJA for primary hip and knee OA, clinical practice and instruments typically focus on OA symptoms negatively impacting quality of life and radiographic evidence of OA, while trial of conservative treatments is less reported. The appropriateness decision-making process poorly acknowledges or supports patient preferences (e.g., shared decision-making). Appropriateness of elective TJA needs to be reconsidered and conceptualized in a way that supports early conservative treatments and patient-centred care.

The COVID-19 pandemic resulted in the cancellation of many hip and knee replacements, creating a backlog of patients on top of an existing long waiting list. To reduce wait lists with no financial burden, we aim to evaluate the possibility of leveraging our previous efficiency-improving work to add an additional case to a typical 4-joint day with no extra cost. To do this, 761 total operation days were analyzed from 2012 to 2019, capturing variables such as case number, success (completion of 4 cases before 3:45pm), and patient out of room time. Linear regression was used on 301 successful days to predict 5th cases, while overtime hours saved were calculated from the remaining unsuccessful days. Different cost distributions were then analyzed for a 77% 4-joint day success rate (our baseline), and a 100% 4-joint day success rate. Our predictions show that increasing performance to a 77% success rate can lead to approximately 35 extra cases per year at our institution, while a 100% success rate can produce 56 extra cases per year. Overall, this shows the extent of resources wasted by overtime costs, and the potential for their use in reducing wait times. Future work can explore optimal staffing procedures to account for these extra cases.

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