A lightweight, graph-theoretic model of class-based similarity to support object-oriented code reuse.

The work presented in this thesis is principally concerned with the development of a method and set of tools designed to support the identification of class-based similarity in collections of object-oriented code. Attention is focused on enhancing the potential for software reuse in situations where a reuse process is either absent or informal, and the characteristics of the organisation are unsuitable, or resources unavailable, to promote and sustain a systematic approach to reuse. The approach builds on the definition of a formal, attributed, relational model that captures the inherent structure of class-based, object-oriented code. Based on code-level analysis, it relies solely on the structural characteristics of the code and the peculiarly object-oriented features of the class as an organising principle: classes, those entities comprising a class, and the intra and inter-class relationships existing between them, are significant factors in defining a two-phase similarity measure as a basis for the comparison process. Established graph-theoretic techniques are adapted and applied via this model to the problem of determining similarity between classes. This thesis illustrates a successful transfer of techniques from the domains of molecular chemistry and computer vision. Both domains provide an existing template for the analysis and comparison of structures as graphs. The inspiration for representing classes as attributed relational graphs, and the application of graph-theoretic techniques and algorithms to their comparison, arose out of a well-founded intuition that a common basis in graph-theory was sufficient to enable a reasonable transfer of these techniques to the problem of determining similarity in object-oriented code. The practical application of this work relates to the identification and indexing of instances of recurring, class-based, common structure present in established and evolving collections of object-oriented code. A classification so generated additionally provides a framework for class-based matching over an existing code-base, both from the perspective of newly introduced classes, and search "templates" provided by those incomplete, iteratively constructed and refined classes associated with current and on-going development. The tools and techniques developed here provide support for enabling and improving shared awareness of reuse opportunity, based on analysing structural similarity in past and ongoing development, tools and techniques that can in turn be seen as part of a process of domain analysis, capable of stimulating the evolution of a systematic reuse ethic

5 year results of a randomised trial of robotic arm assisted vs manual unicompartmental knee arthoplasty

Background:Robotic arm assisted surgery in unicompartmental knee arthroplasty (UKA) resulted in better early post-operative pain and clinical outcomes, but this was lost at two years. In the subgroup of patients with increased pre-operative activity levels, observed improved functional outcomes in the robotic assisted UKA group persisted to two years. Early evidence suggests that robotic arm assisted surgery can deliver more accurate implant positioning, improved lower limb alignment, improved soft tissue balancing compared to conventional surgery. Mid-term survivorship of this randomised control cohort are presented.Objectives:Comparison of mid-term clinical outcomes of a single centred, prospective, randomised control trial comparing robotic arm assisted vs manual conventional UKAs.Study Design & Methods:139 patients were randomised to receive UKA with/without the aid of robotic assistance. Patients were assessed at 3 months, 1 and 2 years post-op. The outcome was assessed using the American Knee Society Score (AKSS), Oxford Knee Score (OKS), Pain VAS, Stiffness VAS, Forgotten Joint Score (FJS), complications and adverse events. Subgroup analysis was performed to examine the outcome in more active patients (UCLA Activity Score>5, n=33, 23.7%).Survivorship of the implant was also reviewed at 5 years in both groups for all patients as part of a Kaplan-Meier survival analysis. Results:There was a difference between the main treatment groups in the AKSS at three months (p=0.042), but not at one year (p=0.098), two years (p=0.951) nor 5 years (p=0.562). No significant differences in the JFS (p=0.783), Pain VAS (p= 0.453), Siffness VAS (0.443) or OKS (p= 0.811) by 5 year time point. In patients who were more active pre-surgery, while there was no significant difference in AKSS at three months (p=0.213), there was a difference at one year in favour of robotic surgery (p=0.007) but these difference were no longer present by 5 years (p= 0.195). In these patients, the OKS was similar at three months (p=0.368), but better in the robotically assisted UKA group at one year (p=0.025), but no significant differences were seen at 5 years (p= 0.314). The VAS pain (p= 0.853) and stiffness (p= 0.132) scores were not different at 5 years.0% of the robotic arm assisted group required readmissions/ further surgery with 9% (6/65, 2 revisions, 1 poly exchange and 3 arthroscopies) of the manual group requiring additional intervention. Conclusions:Excellent mid-term (5 year) survivorship in the robotic arm assisted group represents better survivorship of the implants over the manually performed surgery in this randomised control trial. Robotic assisted surgery in UKA resulted in better early post-operative pain and clinical outcomes up until 2 years, but no difference was found by 5 years between both surgical groups as well as subgroup analysis of patients with increased pre-operative activity levels. Midterm outcomes of the robotic assisted surgery are therefore shown to be similar those of the manual surgical group having previously experienced better early outcome scores. This loss of the difference at midterm follow-up did not include the knees that required additional surgery narrowing of outcome score differences that were lost to follow-up. These revised knees presented the bottom quartile of outcome scores for the manual group

A comparison of gait one year post operation in an RCT of robotic UKA versus traditional Oxford UKA

Robot-assisted unicompartmental knee surgery has been shown to improve the accuracy of implant alignment. However, little research has been conducted to ascertain if this results in a measureable improvement in knee function post operatively and a more normal gait. The kinematics of 70 OA knees were assessed using motion analysis in an RCT (31 receiving robotic-assisted surgery, and 39 receiving traditional manual surgery) and compared to healthy knees. Statistically significant kinematic differences were seen between the two surgical groups from foot-strike to mid-stance. The robotic-assisted group achieved a higher knee excursion (18.0°, SD 4.9°) compared to the manual group (15.7°, SD 4.1°). There were no significant difference between the healthy group and the robotic assisted group, however there was a significant difference between the healthy group and the manual group (p < 0.001). Hence robotically-assisted knee replacement with Mako Restoris Implants appears to lead not only to better implant alignment but also some kinematic benefits to the user during gait

In search of the ideal periosteal flap for bone non-union: the chimeric fibula-periosteal flap

Vascularized periosteal flaps may increase union rates in recalcitrant long bone non-union. The fibula-periosteal chimeric flap utilizes periosteum raised on an independent periosteal vessel. This allows the periosteum to be inset freely around the osteotomy site, thereby facilitating bone consolidation. Patients and Methods: 10 patients underwent fibula-periosteal chimeric flaps (2016 – 2022) at Canniesburn Plastic Surgery Unit, UK. Preceding non-union 18.6 months, with bone gap 7.5 cm. Patients underwent pre-operative CT angiography to identify periosteal branches. A case-control approach was used. Patients acted as their own controls with one osteotomy covered by the chimeric periosteal flap and one without, although in two patients both osteotomies were covered by a long periosteal flap. Results: A chimeric periosteal flap was used in 12 of 20 osteotomy sites. Periosteal flap osteotomies had a primary union rate of 100% (11/11) versus those without 28.6% (2/7) (p=0.0025). Union occurred in the chimeric periosteal flaps at 8.5 months versus 16.75 in the control group (p=0.023). 1 case excluded from primary analysis due to recurrent mycetoma. Number needed to treat = 2, indicating that 2 patients would require a chimeric periosteal flap to avoid one non-union. Survival curves with hazards ratio 4.1, equating to 4 times higher chance of union with periosteal flaps (log rank p=0.0016). Conclusions: The chimeric fibula-periosteal flap may increase consolidation rates in difficult cases of recalcitrant non-union. This elegant modification of the fibula flap uses periosteum that is normally discarded, and adds to accumulating data supporting the use of vascularised periosteal flaps in non-union

Robotic arm-assisted bi-unicompartmental knee arthroplasty maintains natural knee joint anatomy compared with total knee arthroplasty : a prospective randomized controlled trial

Aims The aim of this study was to compare robotic arm-assisted bi-unicompartmental knee arthroplasty (bi-UKA) with conventional mechanically aligned total knee arthroplasty (TKA) in order to determine the changes in the anatomy of the knee and alignment of the lower limb following surgery. Methods An analysis of 38 patients who underwent TKA and 32 who underwent bi-UKA was performed as a secondary study from a prospective, single-centre, randomized controlled trial. CT imaging was used to measure coronal, sagittal, and axial alignment of the knee preoperatively and at three months postoperatively to determine changes in anatomy that had occurred as a result of the surgery. The hip-knee-ankle angle (HKAA) was also measured to identify any differences between the two groups. Results The pre- to postoperative changes in joint anatomy were significantly less in patients undergoing bi-UKA in all three planes in both the femur and tibia, except for femoral sagittal component orientation in which there was no difference. Overall, for the six parameters of alignment (three femoral and three tibial), 47% of bi-UKAs and 24% TKAs had a change of < 2° (p = 0.045). The change in HKAA towards neutral in varus and valgus knees was significantly less in patients undergoing bi-UKA compared with those undergoing TKA (p < 0.001). Alignment was neutral in those undergoing TKA (mean 179.5° (SD 3.2°)) while those undergoing bi-UKA had mild residual varus or valgus alignment (mean 177.8° (SD 3.4°)) (p < 0.001). Conclusion Robotic-assisted, cruciate-sparing bi-UKA maintains the natural anatomy of the knee in the coronal, sagittal, and axial planes better, and may therefore preserve normal joint kinematics, compared with a mechanically aligned TKA. This includes preservation of coronal joint line obliquity. HKAA alignment was corrected towards neutral significantly less in patients undergoing bi-UKA, which may represent restoration of the pre-disease constitutional alignment (p < 0.001)

Improved accuracy of component positioning with robotic-assisted unicompartmental knee arthroplasty : data from a prospective, randomized controlled study

Higher revision rates have been reported in patients who have undergone unicompartmental knee arthroplasty compared with patients who have undergone total knee arthroplasty, with poor component positioning identified as a factor in implant failure. A robotic-assisted surgical procedure has been proposed as a method of improving the accuracy of component implantation in arthroplasty. The aim of this prospective, randomized, single-blinded, controlled trial was to evaluate the accuracy of component positioning in unicompartmental knee arthroplasty comparing robotic-assisted and conventional implantation techniques. One hundred and thirty-nine patients were randomly assigned to treatment with either a robotic-assisted surgical procedure using the MAKO Robotic Interactive Orthopaedic Arm (RIO) system or a conventional surgical procedure using the Oxford Phase-3 unicompartmental knee replacement with traditional instrumentation. A postoperative computed tomographic scan was performed at three months to assess the accuracy of the axial, coronal, and sagittal component positioning. Data were available for 120 patients, sixty-two who had undergone robotic-assisted unicompartmental knee arthroplasty and fifty-eight who had undergone conventional unicompartmental knee arthroplasty. Intraobserver agreement was good for all measured component parameters. The accuracy of component positioning was improved with the use of the robotic-assisted surgical procedure, with lower root mean square errors and significantly lower median errors in all component parameters (p < 0.01). The proportion of patients with component implantation within 2° of the target position was significantly greater in the group who underwent robotic-assisted unicompartmental knee arthroplasty compared with the group who underwent conventional unicompartmental knee arthroscopy with regard to the femoral component sagittal position (57% compared with 26%, p = 0.0008), femoral component coronal position (70% compared with 28%, p = 0.0001), femoral component axial position (53% compared with 31%, p = 0.0163), tibial component sagittal position (80% compared with 22%, p = 0.0001), and tibial component axial position (48% compared with 19%, p = 0.0009). Robotic-assisted surgical procedures with the use of the MAKO RIO lead to improved accuracy of implant positioning compared with conventional unicompartmental knee arthroplasty surgical techniques

A five-year follow up of gait in robotic assisted vs conventional unicompartmental knee arthroplasty

Recently, systems have been developed to improve alignment of unicompartmental knee arthroplasty (UKA) implants, although improvement in function has been difficult to document. The MAKO RIO robotic surgery system has previously shown improvements in in knee flexion during weight acceptance (WA) in comparison to conventional methods at a one year follow up. This study aimed to determine if these improvements remained at five years follow up. Twenty five MAKO and 21 conventional knees were tested using three dimensional gait analysis to measure knee kinematics. Results demonstrated that the MAKO group achieved significantly greater knee flexion in WA than the conventional group which was consistent with results are one year. This could be due to the improved accuracy of prosthesis implantation offered by the MAKO system

5-year gait analysis as a secondary outcome of a fixed bearing robotic assisted versus mobile bearing manual UKA RCT

Total knee arthroplasty (TKA) procedures have recognised differences in knee kinematics and kinetics from healthy knees. This study reports on the less documented knee kinematics and kinetics of uni-compartmental knee arthroplasty (UKA) patients during walking as a secondary outcome measure of a RCT between a fixed bearing UKA robotic procedure versus a mobile bearing UKA manual procedure. Three dimensional, instrumented, gait analysis was performed 5 years after 49 medial osteoarthritis UKA patients received surgery. 27 were randomised to receive a robotic assisted UKA and 22 to receive a manual implant surgery. The robotic assisted group showed a significant increased range of motion in stance during walking. 59% of the robotic assisted group achieved a bi-phasic sagittal knee moment, in comparison of 50% of the manual group. Significantly higher peak values of the varus knee and internal rotation moments were measured for the robotic assisted group during early and late section of the gait cycle, respectively. This indicates that larger normalised forces are applied through the knee during flat ground walking in the robotic assisted group. The robotic assisted group showed biomechanical benefits over the manual group for walking tasks. Poor fixation outcomes are avoided in patients with normal knee moments

Robotic arm-assisted bi-unicompartmental knee arthroplasty maintains natural knee joint anatomy compared with total knee arthroplasty : a prospective, randomised controlled trial

Unicompartmental knee arthroplasty (UKA) is associated with faster postoperative recovery than total knee arthroplasty (TKA), sparing cruciate ligaments and normal joint surfaces. Although registry data indicate that revision rates are higher following UKA than TKA, robotic arm-assistance can improve accuracy of implant positioning and restoration of normal kinematics, when compared to manual implantation. Bi-unicompartmental knee arthroplasty (Bi-UCKA) with manual implantation has been demonstrated to maintain native joint obliquity better than TKA, but not as well as UKAs. There has been no RCT to date examining whether the benefits of UKA hold true for robotic-assisted Bi-UCKA compared to TKA

Niche Occupation Limits Adaptive Radiation in Experimental Microcosms

Adaptive radiations have played a key role in the evolution of biological diversity. The breadth of adaptive radiation in an invading lineage is likely to be influenced by the availability of ecological niches, which will be determined to some extent by the diversity of the resident community. High resident diversity may result in existing ecological niches being filled, inhibiting subsequent adaptive radiation. Conversely, high resident diversity could result in the creation of novel ecological niches or an increase in within niche competition driving niche partitioning, thus promoting subsequent diversification. We tested the role of resident diversity on adaptive radiations in experimental populations of the bacterium Pseudomonas fluorescens that readily diversify into a range of niche specialists when grown in a heterogeneous environment. We allowed an undiversified strain to invade resident communities that varied in the number of niche specialists. The breadth of adaptive radiation attainable by an invading lineage decreased with increasing niche occupation of the resident community. Our results highlight the importance of niche occupation as a constraint on adaptive radiation