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京都大学 / 新制・課程博士 / 博士(医学) / 甲第24527号 / 医博第4969号 / 新制||医||1065(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 黒田 知宏, 教授 大森 孝一, 教授 森本 尚樹 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

The total knee arthroplasty (TKA) has become one of the most successful procedures in all of medicine, with an average of over 966,000 operations performed a year. Since its introduction in 1968, the TKA’s surgical process and implant designs have continuously been improved to increase survivability. However, the need for a revision TKA – due to aseptic loosening – continues to be a problematic aspect of the procedure. Stress shielding induced by different design parameters of the implant has generated controversy in the determination of an ideal configuration. The purpose of this study is to investigate how implant design parameters – fixation technique, stem geometry, cement stiffness, and interface condition – affect the stress shielding within the tibia, and to find an optimal combination of designs that mitigates stress shielding. A CT scan of a tibia was used to simulate multiple configurations of TKAs for finite element analysis in ABAQUS. Stress shielding was assessed by taking the average minimum principal stress of different regions at interval cuts along the depth of the tibia. The results concluded a short, full-cement stem to be the ideal combination of stem length and fixation technique, high-stiffness cement to be ideal for hybrid cements, low-stiffness cement to be ideal for full cements, and a sliding friction interface to be ideal for all models.

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Discharge readiness following total knee replacement (TKR) has often been defined using quantitative factors, such as knee range of motion or walking a specified distance. These measurements fail to include other features that could impact readiness for discharge, such as social support or patient perceptions. Most patients have positive results following TKR surgery, however others experience negative outcomes such as falls, reduced functional performance, and hospital readmission. Readiness for returning home after TKR begins with pre-operative education to prepare patients for surgery and the post-operative phase. Health care providers must have a clear understanding of patients’ perceptions of readiness to return home after surgery. It is also essential to describe the current structure of pre-operative education nationally as a mechanism for better preparing patients to return home following knee replacement. This dissertation includes three studies that explore aspects of discharge readiness following TKR including patients’ perceptions of readiness for discharge as well as the structure of pre-operative education for TKR across the United States. The first study examined patients’ experiences preparing for discharge home from the acute care setting following TKR surgery. Results indicated that patients felt prepared overall for discharge and received appropriate supports for returning home after surgery, but some felt unprepared for certain aspects of recovery such as the amount of pain experienced in the post-operative phase. The second study surveyed health care providers who participated in pre-operative education before TKR to identify the current structure of education programs in the United States. This pilot study revealed that pre-operative education teams were commonly interprofessional with education being typically provided in a group format in a single session lasting between 1 and 1.5 hours. Verbal and written instruction were common delivery methods to provide education. The final dissertation study used mixed-methods to explore the current structure of pre-operative education for TKR in the United States with a large, national sample. Orthopedic nurses completed an online survey to describe their pre-operative education program. The majority of participants provided pre-operative education as part of interprofessional teams in either a group format or a format that included both group and individual education. Verbal instruction was the most common educational delivery method followed by written instruction. Most pre-operative education classes lasted between 1 and 1.5 hours, were delivered in a single session, and included a variety of topics. Ten orthopedic nurses were then interviewed and interview transcripts were analyzed qualitatively for common themes among participants. Participants expressed that pre-operative education was a significant component impacting patient outcomes following surgery. Interprofessional pre-operative education was valued by participants, but pragmatic factors were identified as barriers to the inclusion of other disciplines within these programs. Education programs were constantly evolving based on current evidence-based practice and changes to orthopedic protocols. Descriptions of pre-operative programs nationally combined with providers’ perceptions provides a strong basis for determining best practice to support better post-operative patient outcomes. This dissertation research culminated in recommendations for best practice as well as the creation of a model, the ICF-I-EDUCATE, which combines the International Classification of Health, Functioning and Disability (ICF), interprofessional practice, and the EDUCATE model for providing patient and family education. Research is needed to examine the ICF-I-EDUCATE model in clinical practice for patients with planned TKR.

Disregard for patient-specific joint-level variability may be related to decreased functional ability, poor implant longevity and dissatisfaction post-TKA. The purpose of this study was to, 1) compare pre and post-implant intraoperative passive knee adduction angle kinematic patterns and characterize the effect of surgical intervention on each pattern, 2) examine the association between passive pre and post-implant knee kinematics measured intraoperatively and dynamic knee kinematics and kinetics pre and post-TKA measured during gait, and 3) compare dynamic post-TKA kinematic and kinetic patterns between patient-specific knee recipients and traditional TKA recipient. Patients received a TKA using the Stryker Precision Knee navigation system capturing pre/post-implant kinematics through a passive range of flexion. One-week prior and 1-year post-TKA patients underwent three-dimensional gait analysis. Knee joint waveforms were calculated according to the joint coordinate system. Principal component analysis (PCA) was applied to frontal plane gait angles, moments and navigation angles. Paired two- tailed t-tests were used to compare principal component (PC) scores between pre and post-implant patterns, and a one-way ANOVA was used to test if post-implant patterns were significantly different from zero. Two-tailed Pearson correlation coefficients tested for associations between navigation and gait PCscores, and an un-paired two-tailed t-test was used to compare PCscores between patient-specific and traditional TKA groups. Six different passive kinematic phenotypes were captured pre-implant. Although some waveform patterns persisted at small magnitudes post-implant (PC1 and PC3: p<0.001), curves remained within the clinically acceptable alignment range through passive motion. A positive correlation was found between navigation adduction angle PC1 and gait adduction moment PC1 pre and post-TKA (p<0.001, r=0.79; p<0.01 r=0.67), and a negative correlation between navigation adduction angle PC1 and gait adduction angle PC1 post-TKA (p=0.03, r=-0.53). The patient-specific group showed significantly lower PC2 scores than the traditional TKA group (p=0.03), describing a lower flexion moment magnitude during early stance phase, possibly representing a functional limitation or non- confidence during gait. These results were an important first step to assess patient- specific approaches to TKA, suggesting possible applications for patient-specific intraoperative kinematics to aid in surgical decision-making and influence functional outcomes.

L'arthroplastie totale du genou (ATG) est le traitement de référence de l’ostéoarthrose sévère du genou. Cette procédure nécessite une chirurgie lourde qui induit de nombreux déficits qui persistent pendant plusieurs années. Par ailleurs, les prothèses ont une durée de vie limitée de par les contraintes chimiques et mécaniques se produisant dans l'environnement biologique. Nous avons testé en condition in vivo la biocompatibilité de quatre biomatériaux orthopédiques sous l’effet de l’application de neuro-myélectrostimulation et/ou d’une alimentation enrichie en sel. Nos résultats démontrent que ces deux éléments pourraient avoir un effet délétère pour l'ostéointégration, l'intégrité des implants et la viabilité des cellules musculaires environnantes. Une prothèse adaptée au genou du rat à été conçue afin d’étudier l’effet de l’ATG sur la récupération fonctionnelle et sur les mécanismes nerveux sous-jacents. Nos résultats démontrent que la gonarthrose n'engendre pas de déficits fonctionnels sévères. En revanche, le réflexe H est inhibé et les afférences musculaires de type III et IV sont désensibilisées. Les animaux ayant subi une ATG ont révélé des déficits fonctionnels importants qui tendait à récupérés avec le temps, mais aucune altération de la réponse des fibres afférentes III et IV n'a été observée et le réflexe H est maintenu. Ces résultats soulignent l'adaptation à la prothèse et la présence d'un phénomène de récupération et non d’une compensation. Grâce à notre approche expérimentale innovante, il est maintenant possible de tester in vivo, la biocompatibilité de nouveaux biomatériaux et/ou de nouveaux traitements qui n'ont pas encore d'application clinique. / Total knee arthroplasty (TKA) is the reference treatment for severe osteoarthritis of the knee. This procedure requires heavy surgery which induce many deficits that persist for several years. Moreover, the prostheses have a limited lifetime due to chemical and mechanical stresses occurring in the biological environment. We tested in vivo the effect of the application of neuro-myelectrostimulation and/or high-salt diet on the biocompatibility of four orthopedic biomaterials. Our results show that these two elements could have a deleterious effect on the osseointegration, the integrity of the implants and the viability of the surrounding muscle cells. A prosthesis adapted to knee rat was designed to evaluated the ATG on the functional recovery and on the underlying nervous mechanisms. Our results show that knee osteoarthritis does not cause severe functional deficits. However, H-reflex is inhibited and III and IV afferences are desensitized. Animals with TKA revealed significant functional deficits that tend to recover over time but no impairment of the response of the afferent fibers III and IV was observed and the H reflex was maintained. These results emphasize the adaptation to the prosthesis and the presence of a phenomenon of recovery and not of compensation. Thanks to our innovative experimental approach, it is now possible to test in vivo the biocompatibility of new biomaterials and / or new treatments that have not yet been applied clinically.

Background: Guidelines recommend the use of multiple pharmacologic agents and/or mechanical compressive devices for prevention of venous thromboembolism, but preference for any specific agent is no longer given in regard to safety or efficacy. Objective: To compare postoperative bleeding rates in patients receiving enoxaparin, rivaroxaban, or aspirin for thromboprophylaxis after undergoing elective total hip arthroplasty or total knee arthroplasty. Methods: This retrospective cohort analysis evaluated patients who received thromboprophylaxis with either enoxaparin, rivaroxaban, or aspirin. All data were collected from the electronic medical record. The primary outcome was any postoperative bleeding. Results: A total of 1244 patients were included with 366 in the aspirin, 438 in the enoxaparin, and 440 in the rivaroxaban arms. Those who received aspirin or enoxaparin were less likely to experience any bleeding compared to those patients who received rivaroxaban (P <.05). There was also a lower rate of major bleeding in these groups, but the differences were not significant. Conclusions: Aspirin and enoxaparin conferred similar bleeding risks, and both exhibited less bleeding than patients who received rivaroxaban.