published_or_final_version / Medical Sciences / Master / Master of Medical Sciences

Introduction Mallet finger is a common injury involving either an extensor tendon rupture at its insertion or an avulsion fracture involving the insertion of the terminal extensor tendon. It is usually caused by a forceful blow to the tip of the finger causing sudden flexion or a hyperextension injury. Fracture at the dorsal aspect of the base of the distal phalanx is commonly associated with palmar subluxation of the distal phalanx. Most mallet finger injuries are recommended to be treated with immobilization of the distal interphalangeal joint in extension by splints. However, surgical fixation is still indicated in certain conditions such as open injuries, avulsion fracture involving at least one third of the articular surface with or without palmar subluxation of the distal phalanx and also failed splinting treatment. This study was designed to identify the strongest peak load resistance among four mallet finger fracture fixation methods, namely Kirschner wire fixation, pull-out wire fixation, tension-band wire fixation and the JuggerKnot? (Biomet) soft anchor fixation and to assess the role of the JuggerKnot? technique in mallet finger fixation. Materials and method Four different fixation techniques were assigned among twenty-four specimens (all fingers, no thumbs) from six cadaveric human hands in a randomized block fashion. Only one technique was performed on each finger. A downward load was applied to flex the distal phalanx and the maximum loading force was recorded. The load was tested at 30 degrees, 45 degrees and 60 degrees of flexion of the distal interphalangeal joint. Two separate data sets were performed for each finger before and after the osteotomy and fixation. The data underwent Shapiro-Wilk normality testing before analysis. The values of the mean peak load of the four groups were compared using the one-way analysis of variance test in SPSS version 19.0. Result All data points passed the Shapiro-Wilk test for normality. The mean peak load of the tension-band wiring group was 67.8N at 60 degrees of flexion which was significantly higher than the other three groups (p=0.008). The JuggerKnot? fixation had mean peak loads of 13.35N (30°), 22.51N (45°) and 32.96N (60°) which were all above the required load for mobilization. No complications of implant failure or fragmentation of the dorsal fragment was noted. Discussion The tension-band wire fixation was the strongest fixation method among the four. However it was cumbersome and it had the most soft tissue trauma among the four. No major difficulty was encountered during the testing. No fragmentation of the dorsal fragment was encountered during the procedures. The JuggerKnot? soft anchor fixation was a simple and easy technique and did not require trans-articular Kirschner wire fixation for protection. It could reduce and immobilize a grossly displaced dorsal fragment easily and allowed for safe immediate mobilization of the joint after operation as indicated by the peak load results. This fixation technique was a viable option for treating mallet finger injuries with a dorsal bony fragment size at least one-third of the articular surface with or without palmar subluxation of the distal phalanx. / published_or_final_version / Orthopaedics and Traumatology / Master / Master of Medical Sciences

Thesis (M. Med. Sc.)--University of Hong Kong, 2008. / Includes bibliographical references (p. 38-42)

A research report submitted to the Faculty of Health Sciences, University of the Witwatersrand, in partial fulfilment of the requirements for the degree of Master of Medicine Johannesburg, 2019 / Hand infection is the most common condition seen at Chris Hani Baragwanath Academic Hospital Orthopaedic casualty. In 2017, 31% of orthopaedic admissions at our institution were patients with hand sepsis. Failure to adequately treat these infections results in severe loss of hand function and disability, and this leads to a significant socioeconomic impact in our population. The infected patients are usually started on empiric antibiotics (amoxicillinclavunate (Augmentin)) on admission, and prior to surgical drainage. The purpose of this study was to identify the microbiology profile of hand infections and their antibiotic sensitivity at our institution. The laboratory results of antimicrobial sensitivity were compared with the antibiotics started empirically. The impact of associated co-morbidities on the microbiology profile was also assessed. The results showed that Staphylococcus aureus (S. aureus) is the most common cultured organism. Most organisms were sensitive to cloxacillin. The culture results in HIV infected patients did not differ to those in the uninfected population. Acquired Methicillin-Resistant S. Aureus remains low in our population setting. / E.K. 2019

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MMed (Orthopaedic Surgery), Faculty of Health Sciences, University of the Witwatersrand / Intramedullary nail insertion into a fractured bone allows stabilisation of the fracture with minimal intervention through the zone of injured tissue. This study aimed to assess whether intramedullary nailing of the forearm bones (radius and/or ulna) is a safe and effective form of management of these often complex fractures. A prospective case series was followed from presentation to fracture union. Between April 2006 and February 2008, 21 patients were enrolled in the study. The fracture union rate was high and complication rate was low. There was no increased risk of sepsis. The use of intramedullary nailing for diaphyseal fractures was successful but metaphyseal fractures, particularly with shortening, may be problematic. The use of intramedullary nailing for radius/ulna fractures is safe and effective, however the widespread use of this technique may be limited by the cost of the implant.

Thesis (M. Phil.)--University of Hong Kong, 2002. / Includes bibliographical references.

Thesis (M. Med. Sc.)--University of Hong Kong, 2007.

Thesis (M.S. in mechanical engineering)--Washington State University, December 2006. / Includes bibliographical references (p. 79).

The original Ilizarov frame is a form of circular external fixation in which bone fragments are supported by tensioned fine wires; the wires give the frame a nonlinear axial stiffness which is one of its key qualities. However, as the wires deform plastically in response to loads imposed by functional weight bearing, the stiffness of frame gradually decreases with time. To circumvent this problem the modified Ilizarov frame was conceived in which half pins rather than wires are used for bone support. As fractures managed with Ilizarov fixation tend to unite with little radiographic evidence, monitoring the progression of fracture healing is difficult. The study described in this dissertation had three primary objectives. The first was to investigate the significance of the plastic deformation which occurs in the tensioned fine wires to the long term performance of the original frame. The second was to investigate the biomechanics of the modified frame. The third objective was to conduct a in-vivo feasibility study on the use of fracture axial stiffness measurements as method of monitoring the progression of fracture healing. Plastic deformation of the wires in the original frame readily occurs at moderate load levels because stress concentrations arise at the wire-clamp and wire-bone interfaces. The reduction in frame stiffness is typically 20-30%; re-tensioning only temporarily restores the original frame stiffness. In contrast to the original frame, the modified frame displays a linear stiffness and, as the half pins act as cantilevers, shearing of the bone ends can occur under axial loading. The in-vivo study showed that the technique of relative stiffness measurement, which has been successfully applied to uniaxial fixators, is not directly applicable to Ilizarov fixation. However, it was noted that the standardd eviation of repeatm easurementsd ecreasedw ith the progressiono f healing. It is suggestedt hat this may arise as a result of decreasedm icromovement at the fracture site and might provide a means of monitoring fracture healing itself