Gary J Hooper

University of Otago ·  Department of Orthopaedic Surgery and Musculoskeletal Medicine

Aims The aim of this study was to determine whether obesity had a detrimental effect on the long-term performance and survival of medial unicompartmental knee arthroplasties (UKAs). Methods This study reviewed prospectively collected functional outcome scores and revision rates of all medial UKA patients with recorded BMI performed in Christchurch...

Introduction: This study aimed to examine the changing trends in the reasons for total hip replacement (THR) revision surgery, in one country over a twenty-one-year period, in order to assess whether changes in arthroplasty practices have impacted revision patterns and whether an awareness of these changes can be used to guide clinical practice and...

Introduction Autologous fat grafting has favourable potential as a regenerative strategy and is the current gold-standard to repair large contour defects, as needed in breast reconstruction after mastectomy and traumatic soft tissue reconstruction. Clinically, there is a limit on the volume of lipoaspirate which can be utilised to repair a soft-tis...

INTRODUCTION Stimulation of angiogenesis via the delivery of growth factors (GFs) like vascular endothelial growth factor (VEGF) is a promising strategy for the treatment of avascular necrosis (AVN). Tyraminated poly-vinyl-alcohol hydrogels (PVA-Tyr), which have the ability to covalently incorporate GFs, were proposed as a platform for the controll...

Background Femoral stem design affects periprosthetic bone mineral density (BMD), which may impact long-term survival of cementless implants in total hip arthroplasty (THA). The aim of this study was to examine proximal femoral BMD in 3 morphologically different uncemented femoral stem designs to investigate whether any particular design resulted i...

Background Surgeon‐specific outcome reporting provides an opportunity for quality assurance and improved surgical results. It is becoming increasingly prevalent and remains contentious amongst surgeons. The purpose of this systematic review was to evaluate the extent to which published literature supports the concept that feedback of surgeon‐level...

Osteoarthritis (OA), the commonest arthritis, is characterized by the progressive destruction of cartilage, leading to disability. The Current early clinical treatment strategy for OA often centers on anti-inflammatory or analgesia medication, weight loss, improved muscular function and articular cartilage repair. Although these treatments can reli...

Femoral stem design affects periprosthetic bone mineral density (BMD), which may impact long term survival of cementless implants in total hip arthroplasty (THA). The aim of this study was to examine proximal femoral BMD in three morphologically different uncemented femoral stems designs to investigate whether one particular design resulted in impr...

Background: Surgeon-specific outcome monitoring has become increasingly prevalent over the last three decades. The New Zealand Orthopaedic Association monitors individual surgeon performance through two mechanisms: arthroplasty revision rates derived from the New Zealand Joint Registry, and a practice visit program. Despite remaining confidential,...

Unicompartmental knee arthroplasty (UKA) is associated with a higher risk of revision compared with total knee arthroplasty (TKA). The outcomes of knee arthroplasty are typically presented as implant survival or incidence of revision after a set number of years, which can be difficult for patients and clinicians to conceptualise. We aimed to calcul...

Unicompartmental knee arthroplasty (UKA) has higher revision rates than total knee arthroplasty (TKA). As revision of UKA may be less technically demanding than revision TKA, UKA patients with poor functional outcomes may be more likely to be offered revision than TKA patients with similar outcomes. The aim of this study was to compare clinical thr...

Background: The Oxford Knee Score (OKS) is used to measure knee arthroplasty outcomes, however, it is unclear which questions are more relevant. Our aims were to: 1) identify which OKS question(s) were the strongest predictors of subsequent revision and 2) compare predictive ability of the 'pain' and 'function' domains. Patients and methods: All...

Background: Long-term survivorship and accurate characterization of revision reasons in unicompartmental knee arthroplasty (UKA) are limited by a lack of long-term data and standardized definitions of revision. The aim of this study was to identify survivorship, risk factors, and reasons for revision in a large cohort of medial UKAs with long-term...

Hypochlorous acid (HOCl) is a potent anti-bacterial agent which could reduce periprosthetic joint infection. Early infection complications in joint replacements are often considered to be due to local contamination at the time of surgery and result in a significant socioeconomic cost. Current theatre cleaning procedures produce “clean” operating th...

Femoral stem design affects periprosthetic bone mineral density (BMD), which may impact long term survival of cementless implants in total hip arthroplasty (THA). The aim of this study was to examine proximal femoral BMD in three morphologically different uncemented femoral stems designs to investigate whether one particular design resulted in impr...

Our objective was to examine revision rates and patient reported outcome scores (PROMS) for cemented and uncemented primary total knee joint replacement (TKJR) at six months, one year and five years post-operatively. Patients and Methods: This matched cohort study involved secondary analyses of data collected as part of a large prospective observat...

This study aimed to examine the changing trends in the reasons for total hip replacement (THR) revision surgery, in one country over a twenty-one year period, in order to assess whether changes in arthroplasty practices have impacted revision patterns and whether an awareness of these changes can be used to guide clinical practice and reduce future...

Cementless fixation is an alternative to cemented unicompartmental knee replacement (UKR), with several advantages over cementation. This study reports on the 15-year survival and 10-year clinical outcomes of the cementless Oxford unicompartmental knee replacement (OUKR). This prospective study describes the clinical outcomes and survival of first...

Due to shorter hospital stays and faster patient rehabilitation Unicompartmental Knee Replacements (UKR) are now considered more cost effective than Total Knee Joint Replacements (TKJR). Obesity however, has long been thought of as a relative contraindication to UKR due to an unproven theoretical concern of early loosening. This study is a retrospe...

Source of the study: University of Auckland, Auckland, New Zealand and University of Otago, Christchurch, New Zealand The Oxford Knee Score (OKS) is a 12-item questionnaire used to track knee arthroplasty outcomes. Validation of such patient reported outcome measures is typically anchored to a single question based on patient ‘satisfaction’, howeve...

Source of the study: University of Auckland, Auckland, New Zealand Unicompartmental knee arthroplasty (UKA) is effective for patients with isolated compartment osteoarthritis, however the procedure has higher revision rates. Long-term survivorship and accurate characterisation of revision reasons are limited by a lack of long-term data and standard...

Source of the study: University of Auckland, Auckland, New Zealand and University of Otago, Christchurch, New Zealand Patient reported outcome measures (PROMs) are predictors of knee arthroplasty revision. Unicompartmental knee arthroplasty (UKA) is effective for patients with the correct indications, however has higher revision rates than total kn...

Introduction: The mechanobiology and response of bone formation to strain under physiological loading is well established, however investigation into exceedingly soft scaffolds relative to cancellous bone is limited. In this study we designed and 3D printed mechanically-optimised low-stiffness implants, targeting specific strain ranges inducing bon...

Source of the study: University of Auckland, Auckland, New Zealand and University of Otago, Christchurch, New Zealand Outcomes following knee arthroplasty are typically defined as implant survivorship at defined timepoints, or revision incidence over time. These estimates are difficult to conceptualise, and lack context for younger patients with mo...

Polyetheretherketone (PEEK) interbody fusion cages combined with autologous bone graft is the current clinical gold standard treatment for spinal fusion, however, bone graft harvest increases surgical time, risk of infection and chronic pain. We describe novel low-stiffness 3D Printed titanium interbody cages without autologous bone graft and asses...

Background: Self-reported outcome measures are increasingly being collected for healthcare evaluation therefore it is prudent to understand their associations with patient outcomes. Our aims were to investigate: (1) if Oxford Knee Score (OKS) is associated with impending revision at long-term (5 and 10 years) follow-up, and (2) if decreased OKS at...

To streamline the drug discovery pipeline, there is a pressing need for preclinical models which replicate the complexity and scale of native tumors. While there have been advancements in the formation of microscale tumor units, these models are cell‐line dependent, time‐consuming and have not improved clinical trial success rates. In this study, t...

Cartilage Regeneration Self‐assembled vitreous humor (VH) spheroids fulfill key requirements as reproducible building blocks for 3D‐bioassembly of cartilage tissues. As described by Gabriella C. J. Lindberg and colleagues in article number 2200882, these VH hydrogels promote both cellular migration and neo‐tissue formation in the active interface r...

Lateral integration and fusion of cartilage tissue interfaces remain significantly challenging and limits success of cartilage tissue engineering (TE) strategies. In this study, self-assembled vitreous humor (VH) spheroids are fabricated by seeding clinically relevant human articular chondrocytes (hACs) or human mesenchymal stromal cells (hMSCs) in...

Aims: Unicompartmental knee arthroplasty (UKA) has a higher risk of revision than total knee arthroplasty (TKA), particularly for younger patients. The outcome of knee arthroplasty is typically defined as implant survival or revision incidence after a defined number of years. This can be difficult for patients to conceptualize. We aimed to calcula...

Introduction The Robert Mathys (RM) monoblock uncemented cup is a design less commonly used in primary total hip replacement. It’s purported advantages over modular cemented cups are: (1) its modulus of elasticity approximating bone, thus mimicking load transmission and the biomechanical behaviour of the cup to better match stresses on the acetabul...

Bone regeneration of critical-sized bone defects, bone fractures or joint replacements remains a significant unmet clinical challenge. Although there has been rapid advancement in both the fields of bone tissue engineering and additive manufacturing (AM), functional bone implants with rapid vascularization capacity to ensure osseointegration and lo...

Recently developed modular bioassembly techniques hold tremendous potential in tissue engineering and regenerative medicine, due to their ability to recreate the complex microarchitecture of native tissue. Here, we developed a novel approach to fabricate hybrid tissue-engineered constructs adopting high-throughput microfluidic and 3D bioassembly st...

Objective Increased numbers of joint replacement patients suffering implant wear and/or loosening has created a need for development of non-invasive early diagnosis techniques. Acoustic emission monitoring has shown diagnostic potential for joint replacements, but has not previously been linked to temporal stages of the gait cycle, biomechanical mo...

A tibial tuberosity advancement (TTA), used to treat lameness in the canine stifle, provides a framework to investigate implant performance within an uneven loading environment due to the dominating patellar tendon. The purpose of this study was to reassess how we design orthopaedic implants in a load-bearing model to investigate potential for impr...

With the gradual demographic shift toward an aging and obese society, an increasing number of patients are suffering from bone and cartilage injuries. However, conventional therapies are hindered by the defects of materials, failing to adequately stimulate the necessary cellular response to promote sufficient cartilage regeneration, bone remodeling...

Rifles are often involved in violent deaths such as homicide and suicide. Consequently, expert knowledge and experimental forensic investigations are important to clarify the nature of ballistic trauma when applied to the human head and neurocranium. This study investigated differences in entrance wound morphology with Synbone® spheres which are de...

Aims The success of total knee arthroplasty (TKA) is usually measured using functional outcome scores and revision-free survivorship. However, reporting the lifetime risk of revision may be more meaningful to patients when gauging risks, especially in younger patients. We aimed to assess the lifetime risk of revision for patients in different age c...

Background This study aimed to identify the risk factors, in particularly the use of surgical helmet systems (SHS), for prosthetic joint infection (PJI) following total knee arthroplasty (TKA). Data recorded by the New Zealand Surgical Site Infection Improvement Programme (SSIIP) and the New Zealand Joint Registry (NZJR) were combined and analyzed....

While decades of research have enriched the knowledge of how to grow cells into mature tissues, little is yet known about the next phase: fusing of these engineered tissues into larger functional structures. The specific effect of multicellular interfaces on tissue fusion remains largely unexplored. Here, a facile 3D-bioassembly platform is introdu...

Forensic reconstructions and ballistic testing requires the use of consistent and repeatable simulants. Synthetic bone has been developed to be mechanically similar to human bone; however, it does not have the same viscoelastic properties. Bone acts as brittle and stiff material and fails instantly under high-energy events such as ballistic impacts...

Tissue engineering approaches for bone repair have rapidly evolved due to the development of novel biofabrication technologies, providing an opportunity to fabricate anatomically-accurate living implants with precise placement of specific cell types. However, limited availability of biomaterial inks, that can be 3D-printed with high resolution, whi...

A systematic review of the literature was carried out using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) method to investigate the frequency of military thoracic gunshot wounds (GSWs) and deaths in combat theatres since World War Two (WW2). An electronic database search of World of Science, Scopus, Science Direct,...

Knee and hip arthroplasty are common surgeries within an aging population. Some data has suggested that knee arthroplasty is more traumatic to the body than hip arthroplasty due to the increased complexity and load bearing nature of the joint. Here, we compare the stress of the two surgeries by measuring urinary neopterin and total neopterin as bio...

The paracrine signaling, immunogenic properties and possible applications of mesenchymal stromal cells (MSCs) for cartilage tissue engineering and regenerative medicine therapies have been investigated through numerous in vitro, animal model and clinical studies. The emerging knowledge largely supports the concept of MSCs as signaling and modulator...

There remains a critical need to develop new technologies and materials that can meet the demands of treating large bone defects. The advancement of 3-dimensional (3D) printing technologies has allowed the creation of personalized and customized bone grafts, with specific control in both macro- and micro-architecture, and desired mechanical propert...

Detection of early osteoarthritis to stabilize or reverse the damage to articular cartilage would improve patient function, reduce disability, and limit the need for joint replacement. In this study, we investigated nondestructive photon-processing spectral computed tomography (CT) for the quantitative measurement of the glycosaminoglycan (GAG) con...

Background In ballistic testing and forensic reconstruction, there is a need to use repeatable and consistent simulants. While synthetic bone is mechanically similar to human bone, it does not have the same viscoelastic properties. In high-energy impact such as ballistic impacts, bone acts as a stiff, brittle material and fails instantaneously. The...

Radical photo-cross-linking of polymers has been at the forefront in the development of biomedical applications to meet many of the biomaterial design criteria needed to address clinical and healthcare challenges, particularly in relation to regenerative and restorative medicine strategies, to treat damaged or diseased tissues and organs. Exciting...

Aims Joint registries typically use revision of an implant as an endpoint and report survival rates after a defined number of years. However, reporting lifetime risk of revision may be more meaningful, especially in younger patients. We aimed to assess lifetime risk of revision for patients in defined age groups at the time of primary surgery. Met...

Background and purpose — A challenge comparing outcomes from total hip arthroplasty between countries is variation in preoperative characteristics, particularly comorbidity. Therefore, we investigated between-country variation in comorbidity in patients based on ASA class distribution, and determined any variation of ASA class to mortality risk bet...

The evolution of additive manufacturing (AM) technologies, biomaterial development and our increasing understanding of cell biology has created enormous potential for the development of personalized regenerative therapies. In the context of skeletal tissue engineering, physical and biological demands play key roles towards successful construct impl...

Background: Osteoarthritis (OA) of the knee is a common cause of chronic pain. The currently available analgesics have limited efficacy and may be poorly tolerated. Aim: To investigate the analgesic efficacy of nortriptyline in people with knee OA. Design and setting: A two-arm parallel-group 1:1 double blind randomised placebo-controlled tria...

Background Periprosthetic femoral fractures around total hip arthroplasty (THA) are increasing annually, and are a major cause for revision surgery in the New Zealand Joint Registry (NZJR). The aim of this study was to determine the timing and risk factors for periprosthetic femoral fractures in THA requiring revision surgery in the NZJR. Methods...

PurposeWe examined associations between self-reported and clinician-assessed comorbidity and quality of life (QOL) outcomes after hip and knee replacement.Methods This is a cross-sectional, questionnaire-based national survey. Participants aged 45 years or older (n = 409) were recruited from the New Zealand Joint Registry six months after a total h...

While tissue simulants are considered best practice for ballistic evaluations, there is an ongoing debate about the use of tissue simulant and their relevance and there are calls to improve models by making them more anatomically relevant by the introduction of bony structures and organs. Therefore; the aim of this study was to try and determine if...

Aims: For older patients with hip fracture, we explored patient characteristics, outcomes and osteoporosis treatments for those admitted to rehabilitation compared to those discharged directly from hospital, using data set analysis. Methods: Retrospective cohort study including all consecutive patients (65 years and over) admitted to Christchurc...

IntroductionSynthetic skin simulants are used both in wound ballistics and forensic investigations and should display similar mechanical properties to human tissue and therefore need to be validated. It is recognised that skin simulants may have a significantly different performance when different backing combinations are used; therefore, it is ess...

The translation of growth factors (GFs) into clinical applications is limited by their low stability in physiological environments. Controlled GF delivery through biomaterial vehicles provides protection from proteases, targeted delivery, and longer term release profiles. However, current methods used to incorporate GFs into biomaterials still pres...

Background The prevalence of civilian 0.223 ammunition is widespread. Due to low costs and the same dimensions as a 5.56×45 mm North Atlantic Treaty Organization, this round is exceptionally popular. However, recent mass shootings have employed soft point (SP) expanding ammunition to cause grievous wounds compared with military full metal jacket (F...

Background Handguns and rifles are often involved in violent deaths such as homicide and suicide. Consequently, forensic investigations are important to clarify the nature of ballistic trauma. Methods This study investigated the differences in entrance and exit wound morphology with Bos taurus (bovine) scapulae that have two cortical layers surrou...

3D bioprinting involves the combination of 3D printing technologies with cells, growth factors and biomaterials, and has been considered as one of the most advanced tools for tissue engineering and regenerative medicine (TERM). However, despite multiple breakthroughs, it is evident that numerous challenges need to be overcome before 3D bioprinting...

Background 3D-printed or additive manufactured acetabular implants are an exciting new technology being used in hip surgery with increasing frequency especially in complex acetabular reconstructions. However, the performance of acetabular components produced by this method for primary THR is unknown. Methods 41,272 uncemented cups in primary THR f...

Extrusion‐based 3D bioprinting is hampered by the inability to print materials of low‐viscosity. In this study, a single initiating system based on ruthenium (Ru) and sodium persulfate (SPS) is utilized for a sequential dual‐step crosslinking approach: 1) primary (partial) crosslinking in absence of light to alter the bioink's rheological profile f...

Introduction A review of ballistic gelatin calibration standards has highlighted that data used from studies with different calibrations methods may not be able to be compared. Calibration of ballistic gelatin did not occur until the mid-1980s when Fackler recognised the deficiencies of uncalibrated gelatin. He determined that the calibration stand...

Background The standard Exeter (Stryker) cemented stem is 150 mm long with standard offsets ranging from 37.5 mm to 56 mm. Exeter short stems of 125 mm are also available in the offsets of 37.5 mm, 44 mm, and 50 mm. In addition, smaller (125 mm or shorter) Exeter cemented stems with offsets of 35.5 mm or less are available. The aim of this study wa...

Aims: Our objective was to describe rehabilitation used before and after joint replacement in New Zealand and evaluate variation based on geography and ethnicity. Methods: In this descriptive cross-sectional questionnaire-based study we recruited participants 45 years or older (n=608) from the New Zealand Joint Registry six months after primary...

Additive manufacturing (AM) of titanium alloys offers the capacity to fabricate patient‐specific implants with defined porous architecture to enhance bone‐implant fixation. However, clinical challenges associated with orthopedic implants include inconsistent osseointegration and biofilm‐associated peri‐implant infection, leading to implant failure....

Objective: To determine the effect on the need for transfusion when intravenous tranexamic acid (TXA) is administered intraoperatively in patients undergoing total hip arthroplasty (THA). Method: A prospective, double blinded, randomised control trial of 88 patients undergoing THA was randomly allocated to receive 1 g of intravenous TXA or norma...

In order to obtain bioactive bone-implant interfaces with enhanced osteogenic capacity, various approaches have been developed to modify surface physicochemical properties of bio-inert titanium and titanium alloys. One promising strategy involves fabricating highly ordered nanotubes (NT) on implant surfaces via electrochemical anodization. However,...

3D bioprinting of constructs for tissue engineering and regenerative medicine has steadily gained attention due to its potential to fabricate anatomically-precise living constructs, localise specific cell types and enable the regeneration of functional tissues in a clinical setting. However, the limited availability of bioinks that can be successfu...

Objective: To examine associations between funding source, use of rehabilitation and outcomes after total joint replacement and to evaluate variations based on demographic characteristics. Design: Cross-sectional, questionnaire-based national survey. Subjects: Participants aged 45 years or older (n = 522) who received either private or public fundi...

Background: Periprosthetic fractures are becoming increasingly common, often leading to poor patient outcomes. The aim of this study was to identify risk factors associated with periprosthetic femoral fractures (PPFFx). Methods: Two independent reviewers conducted a systematic review of the databases MEDLINE, Embase and Cochrane Library accordin...

Background: Recurrent dislocation after THA remains a serious complication that carries with it a high risk of revision surgery. Previous studies have shown reduced dislocation rates with the use of lipped polyethylene (PE) liners in modular uncemented acetabular components, but there may be increased wear because of impingement, which may lead to...