Robin K Strachan | Imperial College London (original) (raw)

Videos by Robin K Strachan

An introductory lecture using Bertrand Russell as an example of a Philosopher who changed his Eth... more An introductory lecture using Bertrand Russell as an example of a Philosopher who changed his Ethical and Philosophical Positions with time thereby permitting description of 'movement' across a Basic 2-Dimensional Psychometric Grid ( 'x' Aggression and 'y' Self-Esteem), where Ethical and Philosophical Positions can be 'mapped '.
Such a System of 2-Dimensional Attitude Analysis can then be used to create a 'Psychometric-Philosophical System' or 'Paradigm' where sets of Dimensions running across the Grid can then be linked to consideration of MetaEthical and Dialectical Philosophical Discourse.
This lecture precedes a set of three further lectures in the 'Cognitio Ideas' Series where more detailed analysis moves on to consider the 3rd or 'Z' axis 'Insight' , with the 4th dimension, as with any Cartesian System, being 'Time'.

40 views

Psychometric-Philosophical Paradigm Videos by Robin K Strachan

Research paper thumbnail of Part 1

YouTube, 2020

Part 1 of a YT video describing ideas upon a Psychometric-Philosophical Paradigm to assist with ... more Part 1 of a YT video describing ideas upon a Psychometric-Philosophical Paradigm to assist with difficulties experienced by Expressivism and MetaEthics concentrating on lower Order thought and using Bertand Russel as example of a Philosopher changing his ethical positions with time.

Part 2 to follow discusses similar ideas regarding higher order thought.

Papers by Robin K Strachan

Research paper thumbnail of Cement pedestal spacer technique for infected two-stage revision knee arthroplasty: Description and comparison of complications

Indian Journal of Orthopaedics, 2019

Background: Infection following total knee arthroplasty (TKA) is a significant complication, with... more Background: Infection following total knee arthroplasty (TKA) is a significant complication, with an incidence of up to 2% in primary TKA and 4%–8% in revision cases. Two-stage revision is the gold standard treatment for long-lasting infections of TKA. The purpose of this study was to describe the cement pedestal spacer technique used in infected two-stage revision knee arthroplasty and compare complications against conventional fixed and mobile cement spacers. Patients and Methods: A retrospective review was conducted in all cases who underwent two-stage TKA revision for infection between 2009 and 2015. These cases were separated into groups depending on the cement spacer utilized (fixed, mobile nonpedestal, and mobile spacers with cement pedestal). The cement pedestal technique involves press fitting a cement cylinder into the femur before definitive spacer insertion. Results: Forty four patients underwent two-stage revision TKA. Fewest complications were observed in the pedestal group, with no spacers having subluxed/tilted. The longest followup was also observed in the pedestal group (mean 52.5 months). Mobile spacers with no cement pedestal displayed the highest reinfection rate (16.7%) and the greatest number of cases with complications (malalignment, subluxation, tilting, and spacer fracture). All patients in the pedestal group were ambulatory after the first-stage revision. Conclusions: The cement pedestal technique minimizes complications by optimizing component positioning and balancing. It also safely extends the indication for an articulated spacer into a set of cases with more extensive bone loss and allows for extended monitoring of inflammatory markers.

Research paper thumbnail of Patellofemoral Joint Navigation in Total Knee Arthroplasty

Patellofemoral complications in total knee arthroplasty (TKA) are common. Patellar tracking can b... more Patellofemoral complications in total knee arthroplasty (TKA) are common. Patellar tracking can be adversely affected by component positioning, soft tissue imbalance and bony deformity. Lateral patellar release rates reported in the literature vary from 6– 40%. Computer assisted surgery has largely been confined to the tibio-femoral component of total knee replacement. However, with recently developed software, it can be used to visualise and quantify patellar tracking and thus guide the precise extent and site of lateral patellar release. The aim of this early study was to define the diagnostic envelope for identification and quantisation of patella maltracking using a current generation patella navigation system. Our previous prospective analysis of 100 patients undergoing primary TKA identified pre-operative radiographic indices that correlate with maltracking of the patellofemoral joint. 20 cases were subsequently selected for computer assisted total knee replacement surgery. Th...

Research paper thumbnail of Intra-operative Raman spectroscopy and ex vivo Raman mapping for assessment of cartilage degradation

Research paper thumbnail of The unicompartmental knee is the preferred side in individuals with both a unicompartmental and total knee arthroplasty

Knee Surgery, Sports Traumatology, Arthroscopy

Purpose To determine the preferred knee in patients with both one total and one unicompartmental ... more Purpose To determine the preferred knee in patients with both one total and one unicompartmental knee arthroplasty. Method Patients simply with a unicompartmental (UKA) and total knee arthroplasty (TKA) on contralateral sides were retrospectively screened from three senior knee surgeon’s logs over a 15 year period. Patients safe and free from other diseases to affect gait were approached. A total of 16 patients (mean age 70 ± 8) agreed to ground reaction force testing on an instrumented treadmill at a fair pace and incline. A gender-ratio identical group of 16 healthy control subjects (mean age 67 ± 10) and 16 patients with ipsilateral medial knee OA (mean age 66 ± 7) were analysed to compare. Results Radiographically the mode preoperative Kellgren–Lawrence knee grade for each side was 3. Postoperatively, the TKA side had a mean coronal femoral component alignment of 7° and a mean tibial coronal alignment of 89° with a mean posterior slope of 5° in the sagittal plane. The UKA side h...

Research paper thumbnail of A case of Cement impaction in an un-resurfaced patella after total knee arthroplasty

Cement impaction in an un-resurfaced patella after total knee arthroplasty Radwane Faroug, Yousaf... more Cement impaction in an un-resurfaced patella after total knee arthroplasty Radwane Faroug, Yousaf Shah and Robin Strachan describe an unusual cause of anterior knee pain following a total knee replacement.

Research paper thumbnail of Methods to Determine Indications for Partial Resurfacing in the Knee Including Arthroscopic Cartilage Mapping and Radiographic Analysis

Journal of Bone Joint Surgery British Volume, Jun 1, 2012

Research paper thumbnail of Stress Testing to Optimise Tibiofemoral and Patellofemoral Dynamics During Computer Assisted Surgical Navigation (Casn)

Journal of Bone Joint Surgery British Volume, Jun 1, 2012

Research paper thumbnail of The Use of Computer-Assisted Surgery During Patellofemoral Arthroplasty

Knee Surgery using Computer Assisted Surgery and Robotics, 2012

Research paper thumbnail of Incidence, natural history and risk factors of deep vein thrombosis in elective knee arthroscopy

Thrombosis and haemostasis, 2001

to determine the incidence, anatomical distribution and extent of deep vein thrombosis (DVT) in l... more to determine the incidence, anatomical distribution and extent of deep vein thrombosis (DVT) in limbs undergoing elective unilateral knee arthroscopy without active prophylaxis, to evaluate its effect on venous function following early diagnosis, and to quantify the impact of risk factors on its incidence. 102 consecutive patients undergoing unilateral knee arthroscopy without prophylaxis were studied. A history was obtained with emphasis on the risk factors for thromboembolism, and physical examination and colour duplex were performed prior to and within a week after surgery. Patients who developed calf DVT were given aspirin (150 mg) and compression stockings; those with proximal DVT were admitted for anticoagulation (heparin followed by warfarin). Follow-up (mean 118 [range 84-168] days) entailed weekly physical and duplex examinations during the first month and monthly thereafter. 8 patients developed calf DVT in the operated leg (incidence 7.84% [95% CI: 2.7%-13.2%]); thrombosi...

Research paper thumbnail of (i) Computer assisted surgical navigation (CASN) in total knee replacement. Soft tissue balancing and the role of dynamic assessment

Orthopaedics and Trauma, 2014

Research paper thumbnail of T1-Weighted Sodium MRI of the Articulator Cartilage in Osteoarthritis: A Cross Sectional and Longitudinal Study

PLoS ONE, 2013

Structural magnetic resonance imaging (MRI) has shown great utility in diagnosing soft tissue bur... more Structural magnetic resonance imaging (MRI) has shown great utility in diagnosing soft tissue burden in osteoarthritis (OA), though MRI measures of cartilage integrity have proven more elusive. Sodium MRI can reflect the proteoglycan content of cartilage; however, it requires specialized hardware, acquisition sequences, and long imaging times. This study was designed to assess the potential of a clinically feasible sodium MRI acquisition to detect differences in the knee cartilage of subjects with OA versus healthy controls (HC), and to determine whether longitudinal changes in sodium content are observed at 3 and 6 months. 28 subjects with primary knee OA and 19 HC subjects age and gender matched were enrolled in this ethically-approved study. At baseline, 3 and 6 months subjects underwent structural MRI and a 0.4ms echo time 3D T1-weighted sodium scan as well as the knee injury and osteoarthritis outcome score (KOOS) and knee pain by visual analogue score (VAS). A standing radiograph of the knee was taken for Kellgren-Lawrence (K-L) scoring. A blinded reader outlined the cartilage on the structural images which was used to determine median T1-weighted sodium concentrations in each region of interest on the co-registered sodium scans. VAS, K-L, and KOOS all significantly separated the OA and HC groups. OA subjects had higher T1-weighted sodium concentrations, most strongly observed in the lateral tibial, lateral femoral and medial patella ROIs. There were no significant changes in cartilage volume or sodium concentration over 6 months. This study has shown that a clinically-feasible sodium MRI at a moderate 3T field strength and imaging time with fluid attenuation by T1 weighting significantly separated HCs from OA subjects.

Research paper thumbnail of Effects of lateral retinacular release on the lateral stability of the patella

Knee Surgery, Sports Traumatology, Arthroscopy, 2006

The objective of this cadaveric study was to evaluate quantitatively the effects of lateral retin... more The objective of this cadaveric study was to evaluate quantitatively the effects of lateral retinacular release on the lateral stability of the patella. A materials testing machine was used to displace the patella of 7 cadaveric specimens 10 mm laterally while measuring the required force, with 175 N quadriceps tension. The patella was connected via a ball-bearing patellar mounting 10 mm deep to the anterior surface to allow rotations. Patellar force-displacement behaviour was tested from 0º to 60º knee flexion. At 0°, 10° and 20° flexion the mean force required to displace the patella 10 mm laterally was reduced significantly due to lateral retinacular release, by 16 to 19 %. The average force required to displace the patella was also reduced for larger flexion angles, although this was not statistically significant. These findings suggest that lateral retinacular release may not be appropriate in treatment of patellar lateral instability.

Research paper thumbnail of Radiographic features predictive of patellar maltracking during total knee arthroplasty

Knee Surgery, Sports Traumatology, Arthroscopy, 2009

Despite improvements in component design and surgical technique, some patients still require late... more Despite improvements in component design and surgical technique, some patients still require lateral retinacular release during TKA to improve patella tracking. We studied 148 fixed-bearing TKAs to identify parameters in pre-operative knee radiographs that would predict intraoperative patellar maltracking. Digital radiographs and software were used to measure coronal alignment, distal femoral valgus angle, proximal tibia varus angle, patellar tilt, patellar shift, Insall-Salvati ratio, and patellar component placement and alignment. Patellar tracking was assessed after all components had been cemented, using both no-touch and modified ''towel clip'' techniques. The only radiographic parameter independently associated with maltracking was patellar shift. The median pre-operative patellar lateral shift in patients who had maltracking was 4.1 mm compared to 0.0 mm in those who did not. Patients who had a patellar shift of more than 3.0 mm had a high likelihood of maltracking, with estimated positive and negative predictive values of 78 and 95%, respectively. Pre-operative patellar shift may thus be clinically relevant for identifying osteoarthritic patients who have a higher likelihood for patellar maltracking during TKA. Variations in the intrinsic risk for maltracking within patient study populations may account for the widely differing reported rates of patellar maltracking, and our data suggest that information on pre-operative patellar shift may be helpful in stratifying these sample populations.

Research paper thumbnail of Arthroscopic appearances of the meniscofemoral ligaments: introducing the “meniscal tug test”

Knee Surgery, Sports Traumatology, Arthroscopy, 2006

To evaluate the feasibility of identifying the anterior and posterior meniscofemoral ligaments (a... more To evaluate the feasibility of identifying the anterior and posterior meniscofemoral ligaments (aMFL and pMFL, respectively) at arthroscopy, both visually and using the "meniscal tug test", which exploits the anatomical attachments of the posterior cruciate ligament (PCL) and MFLs. This is an observational type of study. Arthroscopy using anteromedial and anterolateral portals was performed in 68 knees in 68 patients (36 right, 32 left). The MFLs were identified using several anatomical cues, including their femoral and meniscal attachments, their obliquity relative to the PCL, and the meniscal tug test. Identification was classed as easy or hard by the operating surgeon. From 68 knees, the aMFL was seen and confirmed to be an MFL using the tug test in 60 (88%). Identification of the aMFL was classed as easy in 64 (94%), whilst the pMFL was easy to identify in only 6 (9%) of knees, of which 3 had a ruptured PCL. Thus, with the exception of PCL-deficient knees, it was felt that the meniscal "tug test" as applied in this study was not suitable for the pMFL. The study shows that identification of the aMFL is possible in most knees at arthroscopy, using the "tug test" and other anatomical cues. However, identification of the pMFL may require a posterior portal. A subgroup of PCL injuries in which the MFLs were intact was also observed. The "meniscal tug test" can be used in arthroscopic examinations of the PCL to distinguish between fibres of the true PCL from the MFLs, thus avoiding the misdiagnosis of partial versus complete PCL rupture. This will also aid studies examining the role of the MFLs in stabilising the PCL-deficient knee.

Research paper thumbnail of Internal derangements of the knee associated with patellofemoral joint degeneration

Knee Surgery, Sports Traumatology, Arthroscopy, 2005

Risk factors for osteoarthritis (OA) in the different compartments of the knee are important in t... more Risk factors for osteoarthritis (OA) in the different compartments of the knee are important in the pathogenesis of knee OA [1, 5, 7, 10, 14]. Several studies suggest that the pathogenetic mechanism involved in the patellofemoral and tibiofemoral OA may differ [5, 13, 14]. Isolated patellofemoral joint (PFJ) arthritis is rare and the published rates are 3% to 9% of the knee arthritis [4, 5]. General risk factors for patellofemoral OA have been considered to be obesity, family history and Heberden's nodes [3-5, 13, 14]. Previous history of dislocation episodes, patellofemoral pain, patella surgery, patella maltracking and trochlear morphology have been considered as internal derangements of the knee associated with PFJ arthritis [5, 7, 13, 14]. Ligamentous injuries of the knee, instability, and meniscal tears are factors predisposing for knee arthritis, but their contribution in patellofemoral arthritis is not clear [7, 9-12]. The objective of this study

Research paper thumbnail of T2* measurement of the knee articular cartilage in osteoarthritis at 3T

Journal of Magnetic Resonance Imaging, 2012

Purpose-To measure reproducibility, longitudinal and cross-sectional differences in T2* maps at 3... more Purpose-To measure reproducibility, longitudinal and cross-sectional differences in T2* maps at 3 Tesla (T) in the articular cartilage of the knee in subjects with osteoarthritis (OA) and healthy matched controls. Materials and Methods-MRI data and standing radiographs were acquired from 33 subjects with OA and 21 healthy controls matched for age and gender. Reproducibility was determined by two sessions in the same day, while longitudinal and cross-sectional group differences used visits at baseline, 3 and 6 months. Each visit contained symptomological assessments and an MRI session consisting of high resolution three-dimensional double-echo-steady-state (DESS) and coregistered T2* maps of the most diseased knee. A blinded reader delineated the articular cartilage on the DESS images and median T2* values were reported. Results-T2* values showed an intra-visit reproducibility of 2.0% over the whole cartilage. No longitudinal effects were measured in either group over 6 months. T2* maps revealed a 5.8% longer T2* in the medial tibial cartilage and 7.6% and 6.5% shorter T2* in the patellar and lateral tibial cartilage, respectively, in OA subjects versus controls (P < 0.02). Conclusion-T2* mapping is a repeatable process that showed differences between the OA subject and control groups.

Research paper thumbnail of A Technique of Staged Lateral Release to Correct Patellar Tracking in Total Knee Arthroplasty

The Journal of Arthroplasty, 2009

Optimal patellar tracking and component alignment are important in achieving a well-functioning t... more Optimal patellar tracking and component alignment are important in achieving a well-functioning total knee arthroplasty (TKA). The patella is constrained partly by design of the prosthetic trochlear groove, and patellar tracking is governed by a combination of static and dynamic factors. Maltracking may result from excessive or unbalanced tension in the surrounding soft tissues. This article describes a staged progressive lateral release of the patellar retinaculum in TKA, which is classified into 6 stages. Stage 1 transects the deep lateral patellofemoral ligament; stages 2 to 6 extend the lateral patellar incision distally from vastus lateralis to the tibial tubercle. This technique was used in a series of 96 primary TKAs. We report the rates of the various stages of lateral release and the variables that might affect the decision to perform such a release.

Research paper thumbnail of Unicompartmental Knee Arthroplasty Enables Near Normal Gait at Higher Speeds, Unlike Total Knee Arthroplasty

The Journal of Arthroplasty, 2013

Top walking speed (TWS) was used to compare UKA with TKA. Two groups of 23 patients, well matched... more Top walking speed (TWS) was used to compare UKA with TKA. Two groups of 23 patients, well matched for age, gender, height and weight and radiological severity were recruited based on high functional scores, more than twelve months post UKA or TKA. These were compared with 14 preop patients and 14 normal controls. Their gait was measured at increasing speeds on a treadmill instrumented with force plates. Both arthroplasty groups were significantly faster than the preop OA group. TKA patients walked substantially faster than any previously reported series of knee arthroplasties. UKA patients walked 10% faster than TKA, although not as fast as the normal controls. Stride length was 5% greater and stance time 7% shorter following UKAboth much closer to normal than TKA. Unlike TKA, UKA enables a near normal gait one year after surgery.

An introductory lecture using Bertrand Russell as an example of a Philosopher who changed his Eth... more An introductory lecture using Bertrand Russell as an example of a Philosopher who changed his Ethical and Philosophical Positions with time thereby permitting description of 'movement' across a Basic 2-Dimensional Psychometric Grid ( 'x' Aggression and 'y' Self-Esteem), where Ethical and Philosophical Positions can be 'mapped '.
Such a System of 2-Dimensional Attitude Analysis can then be used to create a 'Psychometric-Philosophical System' or 'Paradigm' where sets of Dimensions running across the Grid can then be linked to consideration of MetaEthical and Dialectical Philosophical Discourse.
This lecture precedes a set of three further lectures in the 'Cognitio Ideas' Series where more detailed analysis moves on to consider the 3rd or 'Z' axis 'Insight' , with the 4th dimension, as with any Cartesian System, being 'Time'.

40 views

Research paper thumbnail of Part 1

YouTube, 2020

Part 1 of a YT video describing ideas upon a Psychometric-Philosophical Paradigm to assist with ... more Part 1 of a YT video describing ideas upon a Psychometric-Philosophical Paradigm to assist with difficulties experienced by Expressivism and MetaEthics concentrating on lower Order thought and using Bertand Russel as example of a Philosopher changing his ethical positions with time.

Part 2 to follow discusses similar ideas regarding higher order thought.

Research paper thumbnail of Cement pedestal spacer technique for infected two-stage revision knee arthroplasty: Description and comparison of complications

Indian Journal of Orthopaedics, 2019

Background: Infection following total knee arthroplasty (TKA) is a significant complication, with... more Background: Infection following total knee arthroplasty (TKA) is a significant complication, with an incidence of up to 2% in primary TKA and 4%–8% in revision cases. Two-stage revision is the gold standard treatment for long-lasting infections of TKA. The purpose of this study was to describe the cement pedestal spacer technique used in infected two-stage revision knee arthroplasty and compare complications against conventional fixed and mobile cement spacers. Patients and Methods: A retrospective review was conducted in all cases who underwent two-stage TKA revision for infection between 2009 and 2015. These cases were separated into groups depending on the cement spacer utilized (fixed, mobile nonpedestal, and mobile spacers with cement pedestal). The cement pedestal technique involves press fitting a cement cylinder into the femur before definitive spacer insertion. Results: Forty four patients underwent two-stage revision TKA. Fewest complications were observed in the pedestal group, with no spacers having subluxed/tilted. The longest followup was also observed in the pedestal group (mean 52.5 months). Mobile spacers with no cement pedestal displayed the highest reinfection rate (16.7%) and the greatest number of cases with complications (malalignment, subluxation, tilting, and spacer fracture). All patients in the pedestal group were ambulatory after the first-stage revision. Conclusions: The cement pedestal technique minimizes complications by optimizing component positioning and balancing. It also safely extends the indication for an articulated spacer into a set of cases with more extensive bone loss and allows for extended monitoring of inflammatory markers.

Research paper thumbnail of Patellofemoral Joint Navigation in Total Knee Arthroplasty

Patellofemoral complications in total knee arthroplasty (TKA) are common. Patellar tracking can b... more Patellofemoral complications in total knee arthroplasty (TKA) are common. Patellar tracking can be adversely affected by component positioning, soft tissue imbalance and bony deformity. Lateral patellar release rates reported in the literature vary from 6– 40%. Computer assisted surgery has largely been confined to the tibio-femoral component of total knee replacement. However, with recently developed software, it can be used to visualise and quantify patellar tracking and thus guide the precise extent and site of lateral patellar release. The aim of this early study was to define the diagnostic envelope for identification and quantisation of patella maltracking using a current generation patella navigation system. Our previous prospective analysis of 100 patients undergoing primary TKA identified pre-operative radiographic indices that correlate with maltracking of the patellofemoral joint. 20 cases were subsequently selected for computer assisted total knee replacement surgery. Th...

Research paper thumbnail of Intra-operative Raman spectroscopy and ex vivo Raman mapping for assessment of cartilage degradation

Research paper thumbnail of The unicompartmental knee is the preferred side in individuals with both a unicompartmental and total knee arthroplasty

Knee Surgery, Sports Traumatology, Arthroscopy

Purpose To determine the preferred knee in patients with both one total and one unicompartmental ... more Purpose To determine the preferred knee in patients with both one total and one unicompartmental knee arthroplasty. Method Patients simply with a unicompartmental (UKA) and total knee arthroplasty (TKA) on contralateral sides were retrospectively screened from three senior knee surgeon’s logs over a 15 year period. Patients safe and free from other diseases to affect gait were approached. A total of 16 patients (mean age 70 ± 8) agreed to ground reaction force testing on an instrumented treadmill at a fair pace and incline. A gender-ratio identical group of 16 healthy control subjects (mean age 67 ± 10) and 16 patients with ipsilateral medial knee OA (mean age 66 ± 7) were analysed to compare. Results Radiographically the mode preoperative Kellgren–Lawrence knee grade for each side was 3. Postoperatively, the TKA side had a mean coronal femoral component alignment of 7° and a mean tibial coronal alignment of 89° with a mean posterior slope of 5° in the sagittal plane. The UKA side h...

Research paper thumbnail of A case of Cement impaction in an un-resurfaced patella after total knee arthroplasty

Cement impaction in an un-resurfaced patella after total knee arthroplasty Radwane Faroug, Yousaf... more Cement impaction in an un-resurfaced patella after total knee arthroplasty Radwane Faroug, Yousaf Shah and Robin Strachan describe an unusual cause of anterior knee pain following a total knee replacement.

Research paper thumbnail of Methods to Determine Indications for Partial Resurfacing in the Knee Including Arthroscopic Cartilage Mapping and Radiographic Analysis

Journal of Bone Joint Surgery British Volume, Jun 1, 2012

Research paper thumbnail of Stress Testing to Optimise Tibiofemoral and Patellofemoral Dynamics During Computer Assisted Surgical Navigation (Casn)

Journal of Bone Joint Surgery British Volume, Jun 1, 2012

Research paper thumbnail of The Use of Computer-Assisted Surgery During Patellofemoral Arthroplasty

Knee Surgery using Computer Assisted Surgery and Robotics, 2012

Research paper thumbnail of Incidence, natural history and risk factors of deep vein thrombosis in elective knee arthroscopy

Thrombosis and haemostasis, 2001

to determine the incidence, anatomical distribution and extent of deep vein thrombosis (DVT) in l... more to determine the incidence, anatomical distribution and extent of deep vein thrombosis (DVT) in limbs undergoing elective unilateral knee arthroscopy without active prophylaxis, to evaluate its effect on venous function following early diagnosis, and to quantify the impact of risk factors on its incidence. 102 consecutive patients undergoing unilateral knee arthroscopy without prophylaxis were studied. A history was obtained with emphasis on the risk factors for thromboembolism, and physical examination and colour duplex were performed prior to and within a week after surgery. Patients who developed calf DVT were given aspirin (150 mg) and compression stockings; those with proximal DVT were admitted for anticoagulation (heparin followed by warfarin). Follow-up (mean 118 [range 84-168] days) entailed weekly physical and duplex examinations during the first month and monthly thereafter. 8 patients developed calf DVT in the operated leg (incidence 7.84% [95% CI: 2.7%-13.2%]); thrombosi...

Research paper thumbnail of (i) Computer assisted surgical navigation (CASN) in total knee replacement. Soft tissue balancing and the role of dynamic assessment

Orthopaedics and Trauma, 2014

Research paper thumbnail of T1-Weighted Sodium MRI of the Articulator Cartilage in Osteoarthritis: A Cross Sectional and Longitudinal Study

PLoS ONE, 2013

Structural magnetic resonance imaging (MRI) has shown great utility in diagnosing soft tissue bur... more Structural magnetic resonance imaging (MRI) has shown great utility in diagnosing soft tissue burden in osteoarthritis (OA), though MRI measures of cartilage integrity have proven more elusive. Sodium MRI can reflect the proteoglycan content of cartilage; however, it requires specialized hardware, acquisition sequences, and long imaging times. This study was designed to assess the potential of a clinically feasible sodium MRI acquisition to detect differences in the knee cartilage of subjects with OA versus healthy controls (HC), and to determine whether longitudinal changes in sodium content are observed at 3 and 6 months. 28 subjects with primary knee OA and 19 HC subjects age and gender matched were enrolled in this ethically-approved study. At baseline, 3 and 6 months subjects underwent structural MRI and a 0.4ms echo time 3D T1-weighted sodium scan as well as the knee injury and osteoarthritis outcome score (KOOS) and knee pain by visual analogue score (VAS). A standing radiograph of the knee was taken for Kellgren-Lawrence (K-L) scoring. A blinded reader outlined the cartilage on the structural images which was used to determine median T1-weighted sodium concentrations in each region of interest on the co-registered sodium scans. VAS, K-L, and KOOS all significantly separated the OA and HC groups. OA subjects had higher T1-weighted sodium concentrations, most strongly observed in the lateral tibial, lateral femoral and medial patella ROIs. There were no significant changes in cartilage volume or sodium concentration over 6 months. This study has shown that a clinically-feasible sodium MRI at a moderate 3T field strength and imaging time with fluid attenuation by T1 weighting significantly separated HCs from OA subjects.

Research paper thumbnail of Effects of lateral retinacular release on the lateral stability of the patella

Knee Surgery, Sports Traumatology, Arthroscopy, 2006

The objective of this cadaveric study was to evaluate quantitatively the effects of lateral retin... more The objective of this cadaveric study was to evaluate quantitatively the effects of lateral retinacular release on the lateral stability of the patella. A materials testing machine was used to displace the patella of 7 cadaveric specimens 10 mm laterally while measuring the required force, with 175 N quadriceps tension. The patella was connected via a ball-bearing patellar mounting 10 mm deep to the anterior surface to allow rotations. Patellar force-displacement behaviour was tested from 0º to 60º knee flexion. At 0°, 10° and 20° flexion the mean force required to displace the patella 10 mm laterally was reduced significantly due to lateral retinacular release, by 16 to 19 %. The average force required to displace the patella was also reduced for larger flexion angles, although this was not statistically significant. These findings suggest that lateral retinacular release may not be appropriate in treatment of patellar lateral instability.

Research paper thumbnail of Radiographic features predictive of patellar maltracking during total knee arthroplasty

Knee Surgery, Sports Traumatology, Arthroscopy, 2009

Despite improvements in component design and surgical technique, some patients still require late... more Despite improvements in component design and surgical technique, some patients still require lateral retinacular release during TKA to improve patella tracking. We studied 148 fixed-bearing TKAs to identify parameters in pre-operative knee radiographs that would predict intraoperative patellar maltracking. Digital radiographs and software were used to measure coronal alignment, distal femoral valgus angle, proximal tibia varus angle, patellar tilt, patellar shift, Insall-Salvati ratio, and patellar component placement and alignment. Patellar tracking was assessed after all components had been cemented, using both no-touch and modified ''towel clip'' techniques. The only radiographic parameter independently associated with maltracking was patellar shift. The median pre-operative patellar lateral shift in patients who had maltracking was 4.1 mm compared to 0.0 mm in those who did not. Patients who had a patellar shift of more than 3.0 mm had a high likelihood of maltracking, with estimated positive and negative predictive values of 78 and 95%, respectively. Pre-operative patellar shift may thus be clinically relevant for identifying osteoarthritic patients who have a higher likelihood for patellar maltracking during TKA. Variations in the intrinsic risk for maltracking within patient study populations may account for the widely differing reported rates of patellar maltracking, and our data suggest that information on pre-operative patellar shift may be helpful in stratifying these sample populations.

Research paper thumbnail of Arthroscopic appearances of the meniscofemoral ligaments: introducing the “meniscal tug test”

Knee Surgery, Sports Traumatology, Arthroscopy, 2006

To evaluate the feasibility of identifying the anterior and posterior meniscofemoral ligaments (a... more To evaluate the feasibility of identifying the anterior and posterior meniscofemoral ligaments (aMFL and pMFL, respectively) at arthroscopy, both visually and using the &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;meniscal tug test&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;, which exploits the anatomical attachments of the posterior cruciate ligament (PCL) and MFLs. This is an observational type of study. Arthroscopy using anteromedial and anterolateral portals was performed in 68 knees in 68 patients (36 right, 32 left). The MFLs were identified using several anatomical cues, including their femoral and meniscal attachments, their obliquity relative to the PCL, and the meniscal tug test. Identification was classed as easy or hard by the operating surgeon. From 68 knees, the aMFL was seen and confirmed to be an MFL using the tug test in 60 (88%). Identification of the aMFL was classed as easy in 64 (94%), whilst the pMFL was easy to identify in only 6 (9%) of knees, of which 3 had a ruptured PCL. Thus, with the exception of PCL-deficient knees, it was felt that the meniscal &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;tug test&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot; as applied in this study was not suitable for the pMFL. The study shows that identification of the aMFL is possible in most knees at arthroscopy, using the &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;tug test&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot; and other anatomical cues. However, identification of the pMFL may require a posterior portal. A subgroup of PCL injuries in which the MFLs were intact was also observed. The &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;meniscal tug test&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot; can be used in arthroscopic examinations of the PCL to distinguish between fibres of the true PCL from the MFLs, thus avoiding the misdiagnosis of partial versus complete PCL rupture. This will also aid studies examining the role of the MFLs in stabilising the PCL-deficient knee.

Research paper thumbnail of Internal derangements of the knee associated with patellofemoral joint degeneration

Knee Surgery, Sports Traumatology, Arthroscopy, 2005

Risk factors for osteoarthritis (OA) in the different compartments of the knee are important in t... more Risk factors for osteoarthritis (OA) in the different compartments of the knee are important in the pathogenesis of knee OA [1, 5, 7, 10, 14]. Several studies suggest that the pathogenetic mechanism involved in the patellofemoral and tibiofemoral OA may differ [5, 13, 14]. Isolated patellofemoral joint (PFJ) arthritis is rare and the published rates are 3% to 9% of the knee arthritis [4, 5]. General risk factors for patellofemoral OA have been considered to be obesity, family history and Heberden's nodes [3-5, 13, 14]. Previous history of dislocation episodes, patellofemoral pain, patella surgery, patella maltracking and trochlear morphology have been considered as internal derangements of the knee associated with PFJ arthritis [5, 7, 13, 14]. Ligamentous injuries of the knee, instability, and meniscal tears are factors predisposing for knee arthritis, but their contribution in patellofemoral arthritis is not clear [7, 9-12]. The objective of this study

Research paper thumbnail of T2* measurement of the knee articular cartilage in osteoarthritis at 3T

Journal of Magnetic Resonance Imaging, 2012

Purpose-To measure reproducibility, longitudinal and cross-sectional differences in T2* maps at 3... more Purpose-To measure reproducibility, longitudinal and cross-sectional differences in T2* maps at 3 Tesla (T) in the articular cartilage of the knee in subjects with osteoarthritis (OA) and healthy matched controls. Materials and Methods-MRI data and standing radiographs were acquired from 33 subjects with OA and 21 healthy controls matched for age and gender. Reproducibility was determined by two sessions in the same day, while longitudinal and cross-sectional group differences used visits at baseline, 3 and 6 months. Each visit contained symptomological assessments and an MRI session consisting of high resolution three-dimensional double-echo-steady-state (DESS) and coregistered T2* maps of the most diseased knee. A blinded reader delineated the articular cartilage on the DESS images and median T2* values were reported. Results-T2* values showed an intra-visit reproducibility of 2.0% over the whole cartilage. No longitudinal effects were measured in either group over 6 months. T2* maps revealed a 5.8% longer T2* in the medial tibial cartilage and 7.6% and 6.5% shorter T2* in the patellar and lateral tibial cartilage, respectively, in OA subjects versus controls (P < 0.02). Conclusion-T2* mapping is a repeatable process that showed differences between the OA subject and control groups.

Research paper thumbnail of A Technique of Staged Lateral Release to Correct Patellar Tracking in Total Knee Arthroplasty

The Journal of Arthroplasty, 2009

Optimal patellar tracking and component alignment are important in achieving a well-functioning t... more Optimal patellar tracking and component alignment are important in achieving a well-functioning total knee arthroplasty (TKA). The patella is constrained partly by design of the prosthetic trochlear groove, and patellar tracking is governed by a combination of static and dynamic factors. Maltracking may result from excessive or unbalanced tension in the surrounding soft tissues. This article describes a staged progressive lateral release of the patellar retinaculum in TKA, which is classified into 6 stages. Stage 1 transects the deep lateral patellofemoral ligament; stages 2 to 6 extend the lateral patellar incision distally from vastus lateralis to the tibial tubercle. This technique was used in a series of 96 primary TKAs. We report the rates of the various stages of lateral release and the variables that might affect the decision to perform such a release.

Research paper thumbnail of Unicompartmental Knee Arthroplasty Enables Near Normal Gait at Higher Speeds, Unlike Total Knee Arthroplasty

The Journal of Arthroplasty, 2013

Top walking speed (TWS) was used to compare UKA with TKA. Two groups of 23 patients, well matched... more Top walking speed (TWS) was used to compare UKA with TKA. Two groups of 23 patients, well matched for age, gender, height and weight and radiological severity were recruited based on high functional scores, more than twelve months post UKA or TKA. These were compared with 14 preop patients and 14 normal controls. Their gait was measured at increasing speeds on a treadmill instrumented with force plates. Both arthroplasty groups were significantly faster than the preop OA group. TKA patients walked substantially faster than any previously reported series of knee arthroplasties. UKA patients walked 10% faster than TKA, although not as fast as the normal controls. Stride length was 5% greater and stance time 7% shorter following UKAboth much closer to normal than TKA. Unlike TKA, UKA enables a near normal gait one year after surgery.

Research paper thumbnail of Chondral lesions of the knee

Arthroscopy: The Journal of Arthroscopic & Related Surgery, 2001

We report a new method of describing and recording chondral lesions of the knee at arthroscopy in... more We report a new method of describing and recording chondral lesions of the knee at arthroscopy in order to permit a more accurate and meaningful analysis of patterns of articular cartilage damage. Type of Study: Case series study. Methods: Data were collected prospectively at 1,000 consecutive arthroscopies by the senior author and chondral lesions were recorded on anatomic articular maps divided into different functional zones. Ten zones on the femur were determined by tibiofemoral weight-bearing and flexion horizons (namely the 0°, 45°, 90°, and 120°horizons as they pass the anterior meniscosynovial junction). Ten zones were determined on the tibia, principally by meniscal relations, and 6 zones on the patella. This allowed the size, Outerbridge grade, and location to be analyzed in relation to mechanism, chronicity, and associated intra-articular pathologies. The recording methods were tested for interobserver reproducibility in 50 subsequent cases at the same arthroscopy by 2 independent observers. The results were analyzed by a third person, and showed a relatively small interobserver error of 7.2% for size for a set of grade 3 and 4 lesions and only a 3% error for site. The Fisher exact test was used. The data sheets were entered onto a computer spreadsheet database using standard software (Excel; Microsoft, Redmond, WA) to permit analysis of the data. Results: There were 1,553 chondral lesions in 853 patients correlated with associated lesions, including 356 meniscal lesions, 230 ligamentous injuries, 440 synovial lesions, and other pathologies. High degrees of correlation have been found between specific lesions and their opposing surfaces and the progression of these with time. Conclusions: The problem of precision of localization of articular lesions in the knee has been recently acknowledged by the International Cartilage Research Society (ICRS). However, such recording ought to take into account both function and contact with other structures. This would appear essential in the assessment of prognosis and comparisons between different treatment regimes.

Research paper thumbnail of Synovial shelves of the knee: association with chondral lesions (SS-42)

Arthroscopy: The Journal of Arthroscopic & Related Surgery, 2004

otic and antibiotic plus ATL146e treated knees indicating clearance of bacteria. Knees in the ant... more otic and antibiotic plus ATL146e treated knees indicating clearance of bacteria. Knees in the antibiotic plus ATL146e knees appeared normal with no effusion or loss of motion. Average WBC counts from the synovial fluid aspirates significantly decreased with treatment of antibiotics alone and antibiotics plus ATL146e. IL-8 assay results revealed considerably increased synovial fluid content compared to baseline values, but treatment with antibiotics plus ATL146e significantly decreased the IL-8 content when compared to other treatment groups (P Ͻ .001) indicating inflammatory response suppression. Histologic grading using Salter's scale (0 ϭ best, 15 ϭ worst) resulted in significantly improved scores in the antibiotic plus ATL146e group (2.79) compared to no treatment (6.70), ATL146e only (6.61), and antibiotics only (5.10) (P Ͻ .00000001). GAG assay revealed no significant difference among treatment groups. Discussion: Results of this study show the addition of an adenosine-2A agonist to antibiotic therapy diminishes WBC chemotaxis and inflammation in the joint, while not compromising the clearance of intraarticular bacteria. Early bacterial clearance with modulation of the inflammatory response may prevent the long-term arthritic effects of joint sepsis. Results of this study influence the future treatment of septic arthritis and prevent the associated morbidity.