Publications by authors named "William R Walsh"

181 Publications

In-Vivo response to a novel pillared surface morphology for osseointegration in an ovine model.

J Mech Behav Biomed Mater 2021 Mar 29;119:104462. Epub 2021 Mar 29.

The University of New South Wales, Australia.

Primary stability and secondary fixation of orthopedic implants to bony tissues are important for healing and long-term functionality. Load sharing and stress transfer are key requirements of an effective implant/tissue interface. This paper presents a novel, macro-scale osseointegration surface morphology which addresses the implant/tissue interface from both the biologic as well as biomechanical perspective. The surface morphology is a controlled, engineered, open topography manifested as discrete pillars projecting from the implant enabling continuous bone ingrowth. The pillared surface is distinct from other porous surfaces and can be differentiated by the localization of the implant material into discrete pillars enabling a continuous mass of bone to freely and easily interdigitate into the pillared structure. Traditional porous structures distribute the implant material throughout the surface forcing the bone to grow in a discontinuous manner. Creating an open and continuous space or "open porosity" in and around the pillar structure allows the bone to easily interdigitate with the implant surface without encumberment from a continuous porous structure. An in-vivo study, using an established ovine model, was undertaken examining the effects of pillar morphology on bone ingrowth and mechanical performance. Cortical and cancellous sites were evaluated utilizing histology, histomophometry, and mechanical pushout, at 4 and 12 weeks. Robust bone ingrowth occurred for all morphologies as was noted in review of the study results. An increase in volume and maturity of bone was noted between the intermediated and final time points. Histomophometry demonstrated over 40% and 80% new bone occupied the available "ingrowth" area at 12 weeks for cancellous and cortical sites (respectively). Histologic review showed little fibrous tissue ingrowth at the interface with no adverse cellular reactions. Testing of cortical samples demonstrated a significant increase in pushout load between the 4 and 12 week timepoints and a 4-8 fold increase in pushout load as compared to the grit blast control. These results demonstrated the effectiveness of the novel interface for orthopedic applications in an in-vivo ovine model.
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http://dx.doi.org/10.1016/j.jmbbm.2021.104462DOI Listing
March 2021

Single level posterolateral lumbar fusion in a New Zealand White rabbit () model: Surgical anatomy, operative technique, autograft fusion rates, and perioperative care.

JOR Spine 2021 Mar 23;4(1):e1135. Epub 2020 Dec 23.

Surgical and Orthopaedic Research Laboratories, Prince of Wales Clinical School University of New South Wales Sydney, Prince of Wales Hospital Sydney New South Wales Australia.

Introduction: The posterolateral lumbar fusion (PLF) New Zealand White (NZW) () rabbit model is a long-standing surgical technique for the preclinical evaluation of materials for spinal fusion. A detailed understanding of lumbar spine anatomy and perioperative care requirements of rabbits is imperative for correct execution of the model both scientifically and ethically. This study describes the preoperative procedures and surgical techniques used in single level PLF in a NZW rabbit model as it pertains to the animal husbandry, lumbar spine anatomy, anesthesia, surgical approach, and perioperative care of rabbits in a research setting.

Materials And Methods: We describe the surgical technique and perioperative patient care for single level PLF in a NZW rabbit model. Medical records from a single research facility were retrospectively reviewed for adult NZW rabbits that underwent single level PLF (L4-L5) between January 2016 and December 2019. The number of lumbar vertebrae per rabbit, fusion rates at 12 weeks using iliac crest autograft and complications are reported. Skeletal maturity was confirmed by preoperative fluoroscopic and radiographic documented closure of hindlimb physes.

Results: The PLF rabbit surgical model and perioperative patient care is described. PLF was performed in 868 adult female entire NZW rabbits. The majority of rabbits had seven lumbar vertebrae (620/868; 71.4%), followed by six (221/868; 25.5%), and eight (27/868; 3.1%). Fusion rates at 12 weeks for PLF using iliac crest autograft as assessed by manual palpation and radiographic assessment was 76.9% and 70.0%, respectively. Postoperative complications included occasional partial autograft site wound dehiscence due to self-trauma.

Conclusions: For PLF rabbit models, a detailed understanding of the surgical technique, rabbit lumbar anatomy including number of lumbar vertebrae, and dietary and husbandry requirements of rabbits, is essential for execution of the model and animal welfare.
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http://dx.doi.org/10.1002/jsp2.1135DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7984023PMC
March 2021

Functional repair of critically sized femoral defects treated with bioinspired titanium gyroid-sheet scaffolds.

J Mech Behav Biomed Mater 2021 04 4;116:104380. Epub 2021 Feb 4.

Department of Biomedical Engineering, Duke University, Durham, NC, USA; Department of Mechanical Engineering and Materials Science, Duke University, Durham, NC, USA. Electronic address:

Despite the innate ability for bone to remodel and repair, its regeneration has a limit. In these cases of critically sized bone defects (CSBD), the bone deficit must be repaired using reconstructive techniques that support immediate load bearing and encourage bone bridging across the defect. High-strength porous titanium implants offer a solution for treatment of CSBD in which the scaffold can support physiological loads, provide a matrix to guide ingrowth, and carry graft materials and/or biologics. Fabrication of titanium meta-materials via additive manufacturing (AM) has unlocked the potential to modulate mechanical and biological performance to achieve a combination of properties previously unachievable. Meta-material scaffolds with topology based on triply periodic minimal surfaces (TPMS) have gained increasing interest for use in biomedical applications due to their bioinspired nature. Despite enthusiasm for TPMS-based titanium scaffolds due to their high strength to stiffness ratio, high permeability, and curvature similar to trabecular bone, there is little preclinical evidence to support their in vivo response in bone. The present study sought to evaluate the performance of gyroid-sheet titanium scaffolds produced via AM to repair a critically size femoral cortical bone defect in rats. Empty gyroid-sheet scaffolds were shown to repair segmental defects with up to 38% of torsional strength and 54% torsional stiffness of the intact femur (control) at 12-weeks. Gyroid-sheet scaffolds carrying recombinant bone morphogenic protein-2 demonstrated bridging bone growth across the length of the defect, with torsional strength and stiffness superior to that of the intact controls.
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http://dx.doi.org/10.1016/j.jmbbm.2021.104380DOI Listing
April 2021

Inferior Medial Geniculate Artery Branch as an Anatomical Landmark for Hamstring Harvest During Anterior Cruciate Ligament Reconstruction.

Arthrosc Tech 2021 Jan 20;10(1):e177-e180. Epub 2021 Jan 20.

Surgical and Orthopaedic Research Laboratories, Prince of Wales Clinical School, University of New South Wales, Sydney, Australia.

Graft harvesting is often a challenging step of anterior cruciate ligament reconstructions. Accurate isolation of the hamstring tendons at the pes anserinus is crucial to successful graft harvesting. We describe a technique of using a branch of the inferior medial geniculate artery overlying the pes anserinus insertion as an anatomical landmark to localize the hamstring tendons for harvest. By using this vessel as an anatomical landmark, the incision length was decreased and the time required to harvest reduced. This is a highly reproducible technique and will be beneficial for soft tissue harvesting surgeons to ease hamstring graft harvesting.
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http://dx.doi.org/10.1016/j.eats.2020.09.022DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7823099PMC
January 2021

Induction of muscle-regenerative multipotent stem cells from human adipocytes by PDGF-AB and 5-azacytidine.

Sci Adv 2021 Jan 13;7(3). Epub 2021 Jan 13.

Adult Cancer Program, Lowy Cancer Research Centre, UNSW Sydney, Sydney, NSW 2052, Australia.

Terminally differentiated murine osteocytes and adipocytes can be reprogrammed using platelet-derived growth factor-AB and 5-azacytidine into multipotent stem cells with stromal cell characteristics. We have now optimized culture conditions to reprogram human adipocytes into induced multipotent stem (iMS) cells and characterized their molecular and functional properties. Although the basal transcriptomes of adipocyte-derived iMS cells and adipose tissue-derived mesenchymal stem cells were similar, there were changes in histone modifications and CpG methylation at cis-regulatory regions consistent with an epigenetic landscape that was primed for tissue development and differentiation. In a non-specific tissue injury xenograft model, iMS cells contributed directly to muscle, bone, cartilage, and blood vessels, with no evidence of teratogenic potential. In a cardiotoxin muscle injury model, iMS cells contributed specifically to satellite cells and myofibers without ectopic tissue formation. Together, human adipocyte-derived iMS cells regenerate tissues in a context-dependent manner without ectopic or neoplastic growth.
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http://dx.doi.org/10.1126/sciadv.abd1929DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7806226PMC
January 2021

Fatigue implications for bending orthopaedic plates.

Injury 2021 Jan 17. Epub 2021 Jan 17.

Surgical and Orthopaedic Research Laboratories (SORL), School of Clinical Sciences, Faculty of Medicine, UNSW Sydney, Level 1 Clinical Sciences Building, Prince of Wales Hospital, Gate 6 Avoca Street, Randwick, New South Wales (NSW), 2031, Australia; Department of Surgical and Perioperative Sciences (orthopaedics), Sunderby Research Unit, Umea University, Umea, Sweden.

Objectives: - We aimed to investigate how pre-bending affects the mechanical properties, specifically fatigue, of stainless-steel plates.

Methods: - 3.5mm LCP 10-hole plates were pre-bent in 1, 2 and 3 locations to the same overall degree and fatigue testing performed. Finite Element Analysis (FEA) was performed in Strand7 (version 2.4.6) to better understand the failure point of the plates in four-point bending.

Results: - Six different plate pre-bending conditions were tested for resistance to fatigue failure. Increasing the number of pre-bends improved the fatigue resistance with two pre-bends having a mean 509,304 cycles to failure and three pre-bends 491,378 cycles to failure. The region of highest stress and the point of fatigue failure were at the plate's minimum cross-sectional area, which was predicted by the FEA and confirmed with mechanical testing. For plates pre-bent in two locations, the fatigue failure always occurred in the screw hole not in between the positions of the two pre-bends. Non-linear FEA simulation confirmed that work hardening occurs around pre-bend locations, conferring increased fatigue resistance to the holes next to, or between, pre-bend locations.

Conclusions: We found that contrary to orthopaedic folklore, pre-bending of plates is not detrimental to fatigue resistance of the stainless-steel plates we tested. Pre-bending plates in a single plane increased the fatigue properties of the 10-hole stainless-steel plate tested.
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http://dx.doi.org/10.1016/j.injury.2021.01.022DOI Listing
January 2021

Innovation and New Technologies in Spine Surgery, Circa 2020: A Fifty-Year Review.

Front Surg 2020 24;7:575318. Epub 2020 Nov 24.

Rothman's Orthopaedic Institute, Thomas Jefferson University, Philadelphia, PA, United States.

Spine surgery (lumbar, cervical, deformity, and entire spine) has increased in volume and improved in outcomes over the past 50 years because of innovations in surgical techniques and introduction of new technologies to improve patient care. Innovation is described as a process to add value or create change in an enterprise's economic or social potential. This mini review will assess two of three assessments of innovation in spine surgery: scientific publications and patents issued. The review of both scientific publications and issued patents is a unique assessment. The third assessment of innovation: regulatory clearances of medical devices and equipment for spine surgery and their evolution over time, will also be discussed.
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http://dx.doi.org/10.3389/fsurg.2020.575318DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7732641PMC
November 2020

Reduction of bacterial load with the addition of ultraviolet-C disinfection inside the hyperbaric chamber.

Diving Hyperb Med 2020 Dec;50(4):332-337

Surgical and Orthopaedic Research Laboratory, University of New South Wales, Prince of Wales Hospital, Sydney, Australia.

Introduction: Healthcare acquired infections (HAIs) are associated with increased mortality, morbidity and prolonged hospital stays. Microbiological contamination of the hospital environment directly contributes to HAIs. Optimising environmental cleaning reduces transmission of HAIs. The hyperbaric chamber poses a specific challenge for infection control as certain disinfectants and alcohol-based hand sanitisers are prohibited due to fire risk. Patients often possess multiple risk factors for HAIs. This study compared the bacteria remaining on a surface (bioburden) after a standard clean and after adjunctive disinfection with an ultraviolet-C (UV-C) robot.

Methods: Internal hyperbaric chamber surfaces were first manually cleaned with Clinell® universal wipes and the floor was mopped with Whiteley neutral detergent. Allocated surfaces were swabbed using sterile cotton swabs and processed using a standard microbial culture and a bacteria-specific rapid metabolic assay. Bacterial contamination was also measured by direct contact plating on flat surfaces. The plexiglass ports were covered to protect from potential UV-C mediated damage and used as a negative control. A UV-C disinfection robot was then used to disinfect the chamber for 30 min, whereafter surfaces were swabbed again.

Results: There was a significantly greater mean reduction in bioburden following adjunctive UV-C disinfection than with standard cleaning alone. The surfaces not routinely manually cleaned (e.g., bench, phone) showed greatest reduction in bacterial load following UV-C cleaning.

Conclusions: There was a significant reduction in the bacterial load in the chamber following an adjunctive UV-C clean compared with that of a standard clean. Adjunctive cleaning of the hyperbaric chamber environment with a non-touch UV-C device shows promise as a method to reduce HAIs.
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http://dx.doi.org/10.28920/dhm50.4.332-337DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8026220PMC
December 2020

Load Sharing and Endplate Pressure Distribution in Anterior Interbody Fusion Influenced by Graft Choice.

World Neurosurg 2021 Feb 22;146:e336-e340. Epub 2020 Oct 22.

Surgical and Orthopedic Research Laboratories (SORL), Prince of Wales Clinical School, UNSW Sydney, Sydney, Australia.

Background: Cage subsidence is a known complication of spinal fusion. Various aspects of cage design have been investigated for their influence on cage subsidence, whereas the potential contribution of graft material to load sharing is often overlooked. We aimed to determine whether graft in the aperture affects endplate pressure distribution.

Methods: The pressure distributions of a polyetheretherketone interbody cage with 3 different aperture graft conditions were evaluated: empty, demineralized bone matrix, and supercritical CO-treated allograft bone crunch (SCCO).

Results: Graft materials contributed as much as half the load transmission for SCCO, whereas demineralized bone matrix contributed one third. Endplate areas in contact with the cage demonstrated decreased areas within the highest-pressure spectrum with SCCO graft materials compared with empty cages.

Conclusions: Graft choice plays a role in reducing peak endplate pressures. This finding is relevant to implant subsidence, as well as graft loading and remodeling.
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http://dx.doi.org/10.1016/j.wneu.2020.10.084DOI Listing
February 2021

Kinematics of the Feline Antebrachiocarpal Joint from Supination to Pronation.

Vet Comp Orthop Traumatol 2021 Mar 20;34(2):115-123. Epub 2020 Nov 20.

Sydney School of Veterinary Science, Faculty of Science, University of Sydney, New South Wales, Australia.

Objective:  Cats rely on their forelimb mobility for everyday activities including climbing and grooming. Supination and pronation of the forelimb in cats are considered to primarily involve the antebrachium, rather than the carpus. Therefore, our null hypothesis was that there would be no movement of the carpal bones (radial carpal bone, ulnar carpal bone and accessory carpal bone) relative to the ulna during supination and pronation.

Study Design:  Eight feline cadaveric forelimbs were rotated from supination to pronation in a jig and computed tomography was performed in the neutral, supinated and pronated positions. The individual carpal bones were segmented from computed tomography images of the supinated and pronated scans in each of the eight specimens. A feline ulna coordinate system was established and used to quantify the translations and rotations between bones of the proximal carpal row and antebrachium.

Results:  After the carpus was rotated from the initial supinated position into pronation, there was significant translation (x, y and z axes) and rotation (x and y axes) of the proximal row of carpal bones based on absolute magnitude values. Given the differences in translations and rotations of the proximal row of carpal bones, our null hypothesis was rejected.

Conclusion:  The proximal row of carpal bones translate and rotate independently from the ulna in the cat during pronation of the antebrachium. This may have future implications in the diagnosis and management of feline carpal injuries involving the antebrachiocarpal joint.
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http://dx.doi.org/10.1055/s-0040-1719063DOI Listing
March 2021

Sagittal patellar flexion angle measurement determines greater incidence of patella alta in patellar tendinopathy patients.

Knee Surg Sports Traumatol Arthrosc 2020 Nov 21. Epub 2020 Nov 21.

Surgical and Orthopaedic Research Laboratories, Prince of Wales Clinical School, University of New South Wales, Sydney, Australia.

Purpose: The objective of this study was to compare patellar height and patella alta between a control cohort and patients with patellar tendinopathy by the sagittal patellar flexion angle (SPFA) measurement.

Methods: Magnetic resonance imaging (MRI) scans of the knee were obtained from a sports imaging facility and screened to select patients with anterior knee pain. This symptomatic group was divided into two patient cohorts: those with and without MRI features of patellar tendinopathy. Lateral knee radiographs were reviewed and SPFA, knee flexion angle and Insall-Salvati ratio (IS) were measured from the radiographs by two independent reviewers.

Results: A total of 99 patients consisting of 48 patellar tendinopathy patients and 51 control patients were included. There was a significantly higher mean patellar height (p = 0.002, d = 0.639) and a greater patella alta incidence in the patellar tendinopathy cohort (25.0%) compared to the controls (3.9%) (p = 0.022, d = 0.312). Insall-Salvati ratio measurements showed no difference in patella alta incidence between tendinopathy and control cohorts. There was excellent inter- and intra-observer reliability of SPFA measurements (ICC 0.99).

Conclusion: This is the first study to demonstrate a greater incidence of patella alta in patellar tendinopathy patients compared to controls. A greater patella alta incidence amongst patellar tendinopathy patients as defined by SPFA was found to be clinically relevant, as it suggests these patients may comprise the recalcitrant patient subgroup who do not improve with current surgical intervention and may therefore benefit from a biomechanical surgical solution.

Level Of Evidence: III.
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http://dx.doi.org/10.1007/s00167-020-06372-zDOI Listing
November 2020

mHealth Apps for Enhanced Management of Spinal Surgery Patients: A Review.

Front Surg 2020 23;7:573398. Epub 2020 Oct 23.

NeuroSpine Surgery Research Group (NSURG), Sydney, NSW, Australia.

mHealth (mobile health) refers to mobile technologies that aid medical and public health practices. As of February 2019, 81% of Americans own a smartphone, and mHealth applications (apps) have become increasingly common with more than 400,000 mHealth applications currently available. Advancements in mobile technology now allow us to provide personalized up-to-date information, track personal health data, remind and engage patients, and communicate in a cost-effective way. There are new opportunities for healthcare providers to integrate mHealth into clinical practice. We discuss the current scientific evidence, and research into mHealth technology.
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http://dx.doi.org/10.3389/fsurg.2020.573398DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7644511PMC
October 2020

Stand up! Are normal weight-bearing forces sufficient for a 12/14 Morse taper locking in total hip arthroplasty?

Hip Int 2020 Oct 20:1120700020967000. Epub 2020 Oct 20.

Surgical & Orthopaedic Research Laboratories, Prince of Wales Clinical School University of New South Wales, Sydney, NSW, Australia.

Background: The aim of this study was to investigate total hip arthroplasty (THA) Morse taper pull-off strengths after impaction prior to cyclical loading compared to cyclical loading alone. The practical relevance of the experiment is to provide a perspective on what may be clinically satisfactory taper assembly given the spectrum of head tapping patterns used by surgeons, as well as compare traditional impaction performed in standard THA with alternate methods of taper engagement such as ' assembly' used in micro-invasive techniques.

Methods: 36 taper constructs utilising a combination of cobalt-chrome alloy and ceramic-titanium alloy junctions were investigated in wet and dry conditions with cyclical loading of the constructs. Taper disengagement strengths with and without impaction were compared. Secondary investigation of the surface roughness of the heads and tapers was also assessed.

Results: An impaction to a wet taper resulted in a greater pull off force compared to a dry taper with a CoCr head and taper combination. Impacting the head and dryness of the taper did not affect pull off forces of a ceramic femoral head on titanium taper. Pulling a head off a taper significantly alters the head surface roughness.

Conclusion: Impaction of a taper does not provide any benefit over cyclical loading of a taper assembly alone for pull-off strength.
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http://dx.doi.org/10.1177/1120700020967000DOI Listing
October 2020

A New Era of Antibiotics: The Clinical Potential of Antimicrobial Peptides.

Int J Mol Sci 2020 Sep 24;21(19). Epub 2020 Sep 24.

School of Chemistry, University of New South Wales (UNSW) Sydney, Sydney 2052, Australia.

Antimicrobial resistance is a multifaceted crisis, imposing a serious threat to global health. The traditional antibiotic pipeline has been exhausted, prompting research into alternate antimicrobial strategies. Inspired by nature, antimicrobial peptides are rapidly gaining attention for their clinical potential as they present distinct advantages over traditional antibiotics. Antimicrobial peptides are found in all forms of life and demonstrate a pivotal role in the innate immune system. Many antimicrobial peptides are evolutionarily conserved, with limited propensity for resistance. Additionally, chemical modifications to the peptide backbone can be used to improve biological activity and stability and reduce toxicity. This review details the therapeutic potential of peptide-based antimicrobials, as well as the challenges needed to overcome in order for clinical translation. We explore the proposed mechanisms of activity, design of synthetic biomimics, and how this novel class of antimicrobial compound may address the need for effective antibiotics. Finally, we discuss commercially available peptide-based antimicrobials and antimicrobial peptides in clinical trials.
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http://dx.doi.org/10.3390/ijms21197047DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7582481PMC
September 2020

Comparative osteoconductivity of bone void fillers with antibiotics in a critical size bone defect model.

J Mater Sci Mater Med 2020 Aug 25;31(9):80. Epub 2020 Aug 25.

Surgical and Orthopaedic Research Laboratories, UNSW Sydney, Prince of Wales Clinical School, Prince of Wales Hospital, Level 1 Clinical Sciences Building, Randwick, NSW, Australia.

The study aimed to evaluate the comparative osteoconductivity of three commercially available bone void fillers containing gentamicin with respect to new bone, growth, host tissue response and resorption of the implant material. Defects were created in the cancellous bone of the distal femur and proximal tibia of 12-skeletally mature sheep and filled with three commercially available bone void fillers containing gentamicin (Stimulan-G, Cerament-G, Herafill-G). Peripheral blood was taken pre-operatively and at the time of implantation, as well as at intermittent timepoints following surgery to determine systemic gentamicin levels (5-,15- and 30- minutes, 1, 2, 3, 6, 12, 24, 48- and 72-hours, 3-, 6- and 12-weeks). Decalcified, embedded samples were stained with haematoxylin and eosin (H&E) and used to assess the host tissue response and the formation of new bone in the presence of test implant materials. No adverse reactions were noted at harvest at any time points for any cancellous implantation sites with the various implant materials. Comparative microCT analysis of the Stimulan-G, Cerament-G and Herafill-G test materials revealed a similar increase in bone surface area and volume between animals implanted with Stimulan-G or Cerament-G test materials. Animals implanted with Herafill-G test materials demonstrated the lowest increases in bone volume and surface area of the test materials tested, at levels similar to the negative control sites. By 12-weeks, Stimulan-G defects were completely closed with mature bone and bone marrow whilst the Cerament-G material was still present after 12 weeks by histological examination. In conclusion, this study demonstrated differences in the bone regenerative capacity of a range of bone void fillers in an in vivo setting.
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http://dx.doi.org/10.1007/s10856-020-06418-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7447650PMC
August 2020

Undercut macrostructure topography on and within an interbody cage improves biomechanical stability and interbody fusion.

Spine J 2020 11 6;20(11):1876-1886. Epub 2020 Jul 6.

SeaSpine, San Diego, USA.

Background Context: The interface and interactions between an interbody cage, graft material, and host bone can all participate in the fusion. Shortcomings of Poly(aryl-ether-ether-ketone) interbody cages have been addressed with novel titanium surfaces. Titanium surfaces paired with macroscale topography features on the endplates and within the aperture may provide additional benefits.

Purpose: To evaluate the influence of cage design parameters on interbody fusion in a large animal preclinical model.

Study Design/setting: A comparative preclinical large animal model was performed to evaluate how macroscale topography features of an interbody cage can facilitate early integration between the host bone, graft material, and interbody cage and these effects on biomechanical stability and fusion.

Methods: Forty single level interbody fusions (L4-L5) using iliac crest autograft and bilateral pedicle screw fixation were performed in adult sheep to evaluate the effect of undercut macrostructure topography features of an interbody cage on the endplates and within the aperture. Fusions were evaluated at 6 and 12 weeks (n=10 per group) using radiography, microcomputed tomography, biomechanical integrity, and histology endpoints.

Results: The presence of the undercut macrostructures present on the endplates and within the aperture statistically improved biomechanical integrity at 6 and 12 weeks compared with controls. Microcomputed tomography and histology demonstrated bony interdigitation within the endplate and aperture features contributing to the improvement in properties.

Conclusions: The present study demonstrates that Poly(aryl-ether-ether-ketone) implants with titanium surfaces can be augmented by undercut macrostructures present on the endplates and within the aperture to provide opportunities for a series of anchoring points that, with new bone formation and remodelling, result in earlier and improved biomechanical integrity of the treated level.

Clinical Significance: This preclinical study showed that bone interdigitation with the undercut macrostructures present on the endplates and within the aperture resulted in improved fusion and biomechanical stability in a clinically relevant spinal fusion model. Future clinical study is warranted to evaluate such implants' performance in humans.
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http://dx.doi.org/10.1016/j.spinee.2020.06.023DOI Listing
November 2020

Correction to: 3D-printed spine surgery implants: a systematic review of the efficacy and clinical safety profile of patient-specific and off-the-shelf devices.

Eur Spine J 2020 Jul;29(7):1786

Faculty of Medicine, University of New South Wales (UNSW), Sydney, Australia.

Unfortunately, 3rd author's first name was incorrectly published in the original publication. The complete correct name is given below.
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http://dx.doi.org/10.1007/s00586-020-06455-yDOI Listing
July 2020

Moment arm function dictates patella sagittal height anatomy: Rabbit epiphysiodesis model alters limb length ratios and subsequent patellofemoral anatomical development.

J Orthop Res 2021 03 22;39(3):637-647. Epub 2020 May 22.

Surgical and Orthopaedic Research Laboratories (SORL), Prince of Wales Clinical School, UNSW Sydney, Randwick, New South Wales, Australia.

Patellofemoral anatomical dysplasia is associated with patellofemoral instability and pain. The closure of the knee physis occurs at the same age as the peak incidence of patellofemoral dislocation. This study determined the effect on the patellofemoral anatomical development in a rabbit epiphysiodesis model. Twenty-four skeletally immature New Zealand White rabbits were divided into three groups (a) distal femur epiphysiodesis (FE) (b) proximal tibia epiphysiodesis (TE) (c) control; no epiphysiodesis (C) performed at 6 weeks of age. The primary endpoint was shape analysis using three-dimensional reconstructions of micro-computed tomographys (CTs) performed at 30 weeks of age. The limb length ratios (femur:tibia) were significantly different for both FE (mean 0.72, SD 0.0381, P < .001) and TE (mean 0.91, SD 0.0383, P < .001) treatment groups compared to control (mean 0.81, SD 0.0073). Patella height, as measured from the most distal point of the patella to the tibial joint surface (modified Caton-Deschamps measurement), was lower (baja) in the FE and higher (alta) for the TE, compared with the control group. Our findings suggest femoral and tibial shortening can influence the development of the patellofemoral joint, which may be dictated by moment arm function and is potentially responsible for the etiology of patella alta. Future studies are warranted to explore this association further with the view for the development of treatment options for patella alta in human patients.
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http://dx.doi.org/10.1002/jor.24714DOI Listing
March 2021

Performance of Seven Commercially Available Demineralized Bone Matrix Fiber and Putty Products in a Rat Posterolateral Fusion Model.

Front Surg 2020 20;7:10. Epub 2020 Mar 20.

SeaSpine Inc., Carlsbad, CA, United States.

Demineralized bone matrix (DBM) is a widely used bone graft in spinal fusion. Most commercial DBMs are composed of demineralized bone particles (~125-800 microns) suspended in a carrier that provides improved handling but dilutes the osteoinductive component. DBM fibers (DBF) provide improved osteoconductivity and do not require a carrier. It has been suggested that 100% DBF may offer improved performance over particulate-based DBMs with carrier. Seven commercially available DBM products were tested in an athymic rat posterolateral fusion model. There were four 100% DBFs, two DBFs containing a carrier, and one particulate-based DBM containing carrier. The study objectives were to evaluate the performance: (1) compare fusion rate and fusion maturity of six commercially available DBFs and one particulate-based DBM, and (2) assess the effect of carrier on fusion outcomes for DBFs in a posterolateral fusion model. The DBF/DBM products evaluated were: Strand Family, Propel® DBM Fibers, Vesuvius® Demineralized Fibers, Optium® DBM Putty, Grafton® DBF, Grafton Flex, and DBX® Putty. Single-level posterolateral fusion was performed in 69 athymic rats. Fusion was assessed bilaterally after 4 weeks by manual palpation, radiograph and CT for bridging bone. Fusion mass maturity was assessed with a CT maturity grading scale and by histology. Statistical analysis was performed using Fishers Exact Test for categorical data and Kruskal-Wallis Test for non-parametric data. Strand Family achieved 100% fusion (18/18) by manual palpation, radiographic and CT evaluation, significantly higher than Propel Fibers, Vesuvius Fibers, Optium Putty, and DBX Putty, and not statistically higher than Grafton DBF and Grafton Flex. Strand Family provided the highest fusion maturity, with CT maturity grade of 2.3/3.0 and 89% mature fusion rate. Fusion results suggest a detrimental effect of carrier on fusion performance. There were large variations in fusion performance for seven commercially available DBM products in an established preclinical fusion model. There were even significant differences between different 100% DBF products, suggesting that composition alone does not guarantee performance. In the absence of definitive clinical evidence, surgeons should carefully consider available data in valid animal models when selecting demineralized allograft options.
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http://dx.doi.org/10.3389/fsurg.2020.00010DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7099880PMC
March 2020

Distalising tibial tubercle osteotomy decreases patellar tendon force - A treatment rationale for recalcitrant patellar tendinopathy.

Knee 2020 Jun 25;27(3):871-877. Epub 2020 Mar 25.

Surgical and Orthopaedic Research Laboratory of the University of NSW Clinical School at Prince of Wales Hospital, Randwick, Australia; Faculty of Medicine and Health Science, Macquarie University, North Ryde, Australia. Electronic address:

Background: Patellar tendinopathy is an overuse condition affecting athletes, often with a high morbidity if left untreated. High-level evidence fails to support the use of surgery. A tibial tubercle osteotomy (TTO) has been suggested as a surgical option to improve patient outcomes. Our aim was to explore whether a distalising TTO will alter the patellar tendon to quadriceps tendon force ratio and the sagittal patellar tilt.

Methods: Six cadaver limbs were placed in a custom jig with a mechanical testing machine applying cyclical loads of 200-500 N to the quadriceps tendon. The knee was fixed at 0, 15, 30, 45, 60, 75 and 90° of flexion and a buckle transducer recorded the resultant patellar tendon force. Testing was performed with the native tibial tubercle position and with the tubercle distalised by 11 mm. Testing was also performed with the tubercle anteriorised by 10 mm at both of these tubercle positions, a total of four different testing positions.

Results: There was a significant decrease in the patellar tendon to quadriceps tendon force ratio from 30-60° of knee flexion. There was a significant increase in the sagittal patellar tilt at 30° of knee flexion with distalisation.

Conclusion: This biomechanical study shows that the patellar tendon to quadriceps tendon force ratio can be altered with a distalising tibial tubercle osteotomy. A tibial tubercle osteotomy may be a biomechanical treatment option for recalcitrant patellar tendinopathy by decreasing the load through the patellar tendon, allowing the athlete to maintain higher training volumes and loads.
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http://dx.doi.org/10.1016/j.knee.2020.02.022DOI Listing
June 2020

Effects of SCCO, Gamma Irradiation, and Sodium Dodecyl Sulfate Treatments on the Initial Properties of Tendon Allografts.

Int J Mol Sci 2020 Feb 25;21(5). Epub 2020 Feb 25.

Surgical and Orthopedic Research Laboratories, Prince of Wales Clinical School, Prince of Wales Hospital, University of New South Wales, Randwick, NSW 2031, Australia.

Sterile and decellularized allograft tendons are viable biomaterials used in reconstructive surgeries for dense connective tissue injuries. Established allograft processing techniques including gamma irradiation and sodium dodecyl sulfate (SDS) can affect tissue integrity. Supercritical carbon dioxide (SCCO) represents a novel alternative that has the potential to decellularize and sterilize tendons with minimized exposure to denaturants, shortened treatment time, lack of toxic residues, and superior tissue penetration, and thus efficacy. This study attempted to develop a single-step hybrid decellularization and sterilization protocol for tendons that involved SCCO treatment with various chemical additives. The processed tendons were evaluated with mechanical testing, histology, scanning electron microscopy (SEM), and Fourier-transform infrared (FTIR) spectroscopy. Uniaxial mechanical testing showed that tendons treated with SCCO and additive NovaKill Gen2 and 0.1% SDS had significantly higher ( < 0.05) ultimate tensile stress (UTS) and Young's modulus compared to gamma-irradiated and standard-SDS-treated tendons. This was corroborated by the ultrastructural intactness of SCCO-treated tendons as examined by SEM and FTIR spectroscopy, which was not preserved in gamma-irradiated and standard SDS-treated tendons. However, complete decellularization was not achieved by the experimented SCCO-SDS protocols used in this study. The present study therefore serves as a concrete starting point for development of an SCCO-based combined sterilization and decellularization protocol for allograft tendons, where additive choice is to be optimized.
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http://dx.doi.org/10.3390/ijms21051565DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7084268PMC
February 2020

The use of demineralised bone fibres (DBF) in conjunction with supercritical carbon dioxide (SCCO) treated allograft in anterior lumbar interbody fusion (ALIF).

J Spine Surg 2019 Dec;5(4):589-595

NeuroSpine Surgery Research Group (NSURG), Sydney, Australia.

Spinal fusion is a common procedure for the treatment of various spinal pathologies. Since the early days, spinal fusion has been carried out with the use of bone grafts as interbody spacers. With the development of synthetic interbody implants, bone grafts were used to facilitate fusion. Although autograft provides the best outcomes for fusion, allografts have been sought after due to donor site morbidity and other shortcomings. Currently, a vast variety of demineralised bone matrix (DBM) products are available with their methods of processing and preparation impacting their properties and clinical outcomes. Demineralised bone fibres (DBF), a form a DBM can be easily packed into implants when mixed with other substances such as allograft bone and patient's blood providing a scaffold for the mixture. We report two cases of anterior lumbar interbody fusion (ALIF) utilising a titanium-polyetheretherketone (PEEK) interbody cage filled with DBF, allograft and patient's blood with a maximum of 12 months follow-up outcome.
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http://dx.doi.org/10.21037/jss.2019.10.04DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6989944PMC
December 2019

MagnetOs, Vitoss, and Novabone in a Multi-endpoint Study of Posterolateral Fusion: A True Fusion or Not?

Clin Spine Surg 2020 07;33(6):E276-E287

Surgical and Orthopaedic Research Laboratories, Prince of Wales Clinical School, University of New South Wales, Sydney, NSW, Australia.

Study Design: This study was a multi-endpoint analysis of bone graft substitutes implanted as a standalone graft in a clinically relevant Ovine model of instrumented posterolateral spinal fusion (PLF).

Objective: The objective of this study was to obtain high-quality evidence on the efficacy of commercial bone graft substitutes compared with autograft in instrumented PLF using a state-of-the-art model with a complete range of assessment techniques.

Summary Of Background Data: Preclinical and clinical data on the quality of spinal fusions obtained with bone graft substitutes are often limited. Calcium phosphates with submicron topography have shown promising results in PLF, as these are able to induce bone formation in tissues distant from the host bone, which facilitates bony union.

Methods: Nine female, skeletally mature sheep (4-5 y) underwent posterior pedicle screw/rods instrumented PLF at L2-L3 and L4-L5 using the following bone graft materials as a standalone graft per spinal segment: (1) biphasic calcium phosphate with submicron topography (BCP<µm), (2) 45S5 Bioglass (BG), and (3) collagen-β-tricalcium phosphate with a 45S5 Bioglass adjunct (TCP/BG). Autograft bone (AB) was used as a positive control treatment. Twelve weeks after implantation, the spinal segments were evaluated by fusion assessment (manual palpation, x-ray, micro-computed tomography, and histology), fusion mass volume quantification (micro-computed tomography), range of motion (ROM) testing, histologic evaluation, and histomorphometry.

Results: Fusion assessment revealed equivalence between AB and BCP<µm by all fusion assessment methods, whereas BG and TCP/BG led to significantly inferior results. Fusion mass volume was highest for BCP<µm, followed by AB, BG, and TCP/BG. ROM testing determined equivalence for spinal levels treated with AB and BCP<µm, while BG and TCP/BG exhibited higher ROM. Histologic evaluation revealed substantial bone formation in the intertransverse regions for AB and BCP<µm, whereas BG and TCP/BG grafts contained fibrous tissue and minimal bone formation. Histologic observations were supported by the histomorphometry data.

Conclusions: This study reveals clear differences in efficacy between commercially available bone graft substitutes, emphasizing the importance of clinically relevant animal models with multiendpoint analyses for the evaluation of bone graft materials. The results corroborate the efficacy of calcium phosphate with submicron topography, as this was the only material that showed equivalent performance to autograft in achieving spinal fusion.
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http://dx.doi.org/10.1097/BSD.0000000000000920DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7337107PMC
July 2020

C3-C5 Chordoma Resection and Reconstruction with a Three-Dimensional Printed Titanium Patient-Specific Implant.

World Neurosurg 2020 Apr 4;136:226-233. Epub 2019 Dec 4.

Faculty of Medicine, University of New South Wales, Sydney, Australia; Surgical and Orthopaedic Research Laboratories, Prince of Wales Clinical School, University of New South Wales, Sydney, Australia; NeuroSpine Surgery Research Group, Sydney, Australia; Department of Neurosurgery, Prince of Wales Private Hospital, Sydney, Australia.

Background: With this case report, we aim to add to the clinical literature on the use of three-dimensional printed patient-specific implants in spinal surgery, show the current state of the art in patient-specific implant device design, present thorough clinical and radiographic outcomes, and discuss the suitability of titanium alloy as an implant material for patients with cancer.

Case Description: A 45-year-old man presented with neck and left arm pain combined with shoulder weakness. Imaging revealed significant destruction of the C3-C5 vertebrae, and chordoma diagnosis was confirmed by biopsy. Gross total tumor resection including multilevel corpectomy was performed in combination with reconstruction using a three-dimensional printed titanium custom implant. Custom-designed features aimed to reduce reconstruction time and result in good clinical and radiographic outcomes. Clinical scores improved postoperatively and remained improved at 17-month postoperative follow-up: visual analog scale score 10/10 preoperatively improved to 2-6/10 at 17 months; Neck Disability Index 46% preoperatively improved to 32% at 17 months. Neither dysphagia nor dysphonia remained after surgical soft tissue swelling subsided. The patient was successfully treated with proton beam therapy after surgery, with no tumor recurrence at 17-month follow-up. Radiographic assessment showed incomplete fusion at 3 months, with clinically insignificant implant subsidence (2.7 mm) and no implant migration or failure at 14 months.

Conclusions: Computer-aided preoperative planning with three-dimensional printed biomodels and custom implant resulted in relatively quick and simple reconstruction after tumor resection, with good clinical and radiographic outcomes at 17 and 14 months, respectively. For patients with primary tumors who may require follow-up radiotherapy or postoperative magnetic resonance imaging, metals used in the devices cause significant imaging artifact.
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http://dx.doi.org/10.1016/j.wneu.2019.11.167DOI Listing
April 2020

3D-printed spine surgery implants: a systematic review of the efficacy and clinical safety profile of patient-specific and off-the-shelf devices.

Eur Spine J 2020 06 3;29(6):1248-1260. Epub 2019 Dec 3.

Faculty of Medicine, University of New South Wales (UNSW), Sydney, Australia.

Purpose: Three-dimensional printing (3DP), or additive manufacturing, is an emergent fabrication technology for surgical devices. As a production method, 3DP enables physical realisation of surgical implants from geometrically complex digital-models in computer-aided design. Spine surgery has been an innovative adopter of 3DP technology for both patient-specific (PS) and market-available 'Off-The-Shelf' (OTS) implants. The present study assessed clinical evidence for efficacy and safety of both PS and OTS 3DP spinal implants through review of the published literature. The aim was to evaluate the clinical utility of 3DP devices for spinal surgery.

Methods: A systematic literature review of peer-reviewed papers featured on online medical databases evidencing the application of 3DP (PS and OTS) surgical spine implants was conducted in accordance with PRISMA guidelines.

Results: Twenty-two peer-reviewed articles and one book-chapter were eligible for systematic review. The published literature was limited to case reports and case series, with a predominant focus on PS designs fabricated from titanium alloys for surgical reconstruction in cases where neoplasia, infection, trauma or degenerative processes of the spine have precipitated significant anatomical complexity.

Conclusion: PS and 3DP OTS surgical implants have demonstrated considerable utility for the surgical management of complex spine pathology. The reviewed literature indicated that 3DP spinal implants have also been used safely, with positive surgeon- and patient-reported outcomes. However, these conclusions are tentative as the follow-up periods are still relatively short and the number of high-powered studies was limited. Single case and small case series reporting would benefit greatly from more standardised reporting of clinical, radiographic and biomechanical outcomes. These slides can be retrieved under Electronic Supplementary Material.
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http://dx.doi.org/10.1007/s00586-019-06236-2DOI Listing
June 2020

The effect of surgery on patellar tendinopathy: Novel use of MRI questions the exploitability of the rat collagenase model to humans.

Knee 2019 Dec 6;26(6):1182-1191. Epub 2019 Nov 6.

Surgical and Orthopaedic Research Laboratories (SORL), School of Clinical Sciences, Faculty of Medicine, University of New South Wales (UNSW), Level 1 Clinical Sciences Building, Prince of Wales Hospital, Gate 6 Avoca Street, Randwick, New South Wales (NSW) 2031, Australia.

Background: patellar tendinopathy is an overuse condition most commonly affecting jumping athletes. Surgery is reserved for refractory cases; however, it lacks high level clinical evidence and basic science to support its use. The purpose of this study was to determine the biomechanical and histological response of surgical excision on patellar tendinopathy in the rat collagenase tendinopathy model and correlate MRI findings.

Methods: Forty-eight Long Evans rats were divided into three groups: i) no patellar tendinopathy with surgical excision, ii) patella tendinopathy with surgical excision, and iii) patellar tendinopathy with no surgical excision. Endpoints included histology, mechanical testing, and MRI pre- and post-surgical intervention at one and four weeks.

Results: No difference in failure load or histological grading was seen between the groups at all time points. MRIs showed initial loss of tendon continuity followed by complete healing with elongated and thickened tendons in all groups.

Conclusions: While other research has reported immunohistochemistry and histology of collagenase-induced tendinopathy may be correlated with human pathogenesis, the novel MRI findings from our study suggest that the rat collagenase tendinopathy surgical model may be limited when extrapolating to humans. Further work is needed to determine if any correlation exists between the dosing, location, and animal effect of the collagenase injection model with MRI findings. This is needed before any collagenase model can be used to determine the effect of surgery in the pathogenic response to patella tendinopathy.
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http://dx.doi.org/10.1016/j.knee.2019.10.017DOI Listing
December 2019

Biphasic calcium phosphate with submicron surface topography in an model of instrumented posterolateral spinal fusion.

JOR Spine 2018 Dec 28;1(4):e1039. Epub 2018 Nov 28.

Kuros Biosciences BV Bilthoven The Netherlands.

As spinal fusions require large volumes of bone graft, different bone graft substitutes are being investigated as alternatives. A subclass of calcium phosphate materials with submicron surface topography has been shown to be a highly effective bone graft substitute. In this work, a commercially available biphasic calcium phosphate (BCP) with submicron surface topography (MagnetOs; Kuros Biosciences BV) was evaluated in an model of instrumented posterolateral fusion. The material was implanted stand-alone, either as granules (BCP) or as granules embedded within a fast-resorbing polymeric carrier (BCP) and compared to autograft bone (AG). Twenty-five adult, female Merino sheep underwent posterolateral fusion at L2-3 and L4-5 levels with instrumentation. After 6, 12, and 26 weeks, outcomes were evaluated by manual palpation, range of motion (ROM) testing, micro-computed tomography, histology and histomorphometry. Fusion assessment by manual palpation 12 weeks after implantation revealed 100% fusion rates in all treatment groups. The three treatment groups showed a significant decrease in lateral bending at the fusion levels at 12 weeks ( < 0.05) and 26 weeks ( < 0.001) compared to the 6 week time-point. Flexion-extension and axial rotation were also reduced over time, but statistical significance was only reached in flexion-extension for AG and BCP between the 6 and 26 week time-points ( < 0.05). No significant differences in ROM were observed between the treatment groups at any of the time-points investigated. Histological assessment at 12 weeks showed fusion rates of 75%, 92%, and 83% for AG, BCP and BCP, respectively. The fusion rates were further increased 26 weeks postimplantation. Similar trends of bone growth were observed by histomorphometry. The fusion mass consisted of at least 55% bone for all treatment groups 26 weeks after implantation. These results suggest that this BCP with submicron surface topography, in granules or putty form, is a promising alternative to autograft for spinal fusion.
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http://dx.doi.org/10.1002/jsp2.1039DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6686792PMC
December 2018

Wearable inertial sensors and pressure MAT detect risk factors associated with ACL graft failure that are not possible with traditional return to sport assessments.

BMJ Open Sport Exerc Med 2019 2;5(1):e000557. Epub 2019 Jul 2.

Surgical and Orthopaedic Research Laboratory, UNSW, Randwick, New South Wales, Australia.

Introduction: Anterior cruciate ligament reconstruction (ACLR) is associated with poor return to sport and high graft re-rupture rates. This study explored the use of a wearable inertial sensor (ViMove) that incorporates an accelerometer and gyroscope, and MatScan pressure sensing mat (TekScan, South Boston, Massachusetts, USA) to provide objective return-to-sport measures.

Methods: Three cohorts' ACLR patients, non-athletic controls and elite athletes (Australian seven's rugby Olympic Gold medallist). Patients performed biometric and functional tests (thigh circumference and triple hop) and the ViMove knee module (consisting of single and double leg squats, hops and box drops) for lower limb alignment assessment, concurrently with force plate.

Results: Elite athletes had less varus/valgus (VV) movement during ViMove exercises compared with the ACLR cohort, who in turn had less VV malalignment than controls. When analysing side-to-side differences, single leg squats and box drop were asymmetrical in the ACL group, with greater malalignment in the reconstructed leg (p<0.05). Subgroup analysis failed to differentiate who passed or failed current return to sport assessment. TekScan pressure plate detected differences in double leg landing and flight time while hopping not detected with ViMove, suggesting ACL patients compensate by offloading the reconstructed leg to improve coronal alignment during double leg activity.

Conclusion: The inertial sensor detected differences in motion for patients following ACLR, which are known to be associated with graft rupture and were not detected with functional return to sport testing. Coupling the device with data from a pressure plate provides a powerful assessment tool detecting alignment differences known to be associate with graft failure only previously detected in formal gait analysis.
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http://dx.doi.org/10.1136/bmjsem-2019-000557DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6615852PMC
July 2019

Sagittal patellar flexion angle: a novel clinically validated patellar height measurement reflecting patellofemoral kinematics useful throughout knee flexion.

Knee Surg Sports Traumatol Arthrosc 2020 Mar 9;28(3):975-983. Epub 2019 Jul 9.

Surgical and Orthopaedic Research Laboratory, Prince of Wales Hospital, Prince of Wales Clinical School, University of NSW, Barker St, Randwick, 2052, NSW, Australia.

Purpose: Patellar height measurements on lateral radiographs are dependent on knee flexion which makes standardisation of measurements difficult. This study described a plain radiographic measurement of patellar sagittal height which reflects patellofemoral joint kinematics and can be used at all degrees of flexion.

Methods: The study had two parts. Part one involved 44 normal subjects to define equations for expected patellar position based on the knee flexion angles for three new patellar height measurements. A mixed model regression with random effect for individual was used to define linear and polynomial equations for expected patellar position relating to three novel measurements of patella height: (1) patellar progression angle (trochlea), (2) patellar progression angle (condyle) and (3) sagittal patellar flexion. Part two was retrospective and involved applying these measurements to a surgical cohort to identify differences between expected and measured patellar position pre- and post-operatively.

Results: All three measurements provided insight into patellofemoral kinematics. Sagittal patellar flexion was the most useful with the least residual error, was the most reliable, and demonstrated the greatest detection clinically.

Conclusions: Clinically applied radiographic measurements have been described for patellar height which reflect the sagittal motion of the patella and can be used regardless of the degree of flexion in which the radiograph was taken. The expected sagittal patellar flexion linear equation should be used to calculate expected patellar height.

Level Of Evidence: IV.
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http://dx.doi.org/10.1007/s00167-019-05611-2DOI Listing
March 2020