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Orthopaedic Proceedings
Vol. 105-B, Issue SUPP_9 | Pages 71 - 71
17 Apr 2023
Cochrane I Hussain A Kang N Chaudhury S
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During the COVID-19 pandemic, video/phone consultations (VPC) were increasingly utilised as an alternative to face-to-face (F2F) consultations, to minimise nosocomial viral exposure. We previously demonstrated that VPCs were highly rated by both patients and clinicians. This study compared satisfaction between both clinic modalities in contemporaneously delivered outpatient surveys. We also assessed the feasibility and effects of converting F2F orthopaedic consultations to VPC.

Surveys were posted to patients who attended VPCs and F2F consultations at a large tertiary centre from August to October 2020 inclusive, across 51 specialties. F2F and VPC patients ranked their overall satisfaction with their consultation on a 10-point numerical scale (10=highest satisfaction). Simultaneously, a pilot study was undertaken of outpatient fracture clinics to identify patients suitable for VPCs, with X-rays (if needed) taken and transferred from satellite sites to reduce tertiary centre footfall.

For F2F consultations, 1419 of 4465 surveys (31.8%) were returned with similar rates for VPCs (1332 of 4572, 29.1%). While mean satisfaction ratings were high for both clinic modalities, they were significantly higher for F2F: 9.13 (95% CI 9.05-9.22) for F2F clinics, compared to 8.23 (95% CI 8.11-8.35) for VPCs (p<0.001, t-test). F2F patients were almost four times more likely to state a preference for future F2F appointments compared to VPCs, whereas patients who attended VPCs showed an equal preference for either option (p< 0.001, chi2 test). 53% of 111 fracture clinic patients sampled were identified as suitable for VPCs. 1 patient (1.7%) requested their VPC to be converted to F2F due to poor symptom control.

Our study showed patients reported high satisfaction ratings for both F2F clinics and VPCs, with prior experience of VPCs affecting patients’ future preferences. Only 1.7% of F2F patients converted to VPCs declined their virtual appointment. Our results support future use of VPCs.


Orthopaedic Proceedings
Vol. 105-B, Issue SUPP_8 | Pages 43 - 43
11 Apr 2023
Amirouche F Mok J Leonardo Diaz R Forsthoefel C Hussain A
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Lateral lumbar interbody fusion (LLIF) has biomechanical advantages due to the preservation of ligamentous structures (ALL/PLL), and optimal cage height afforded by the strength of the apophyseal ring. We compare the biomechanical motion stability of multiple levels LLIF (4 segments) utilising PEEK interbody 26mm cages to stand-alone cage placement and with supplemental posterior fixation with pedicle screw and rods.

Six lumbar human cadaver specimens were stripped of the paraspinal musculature while preserving the discs, facet joints, and osteoligamentous structures and potted. Specimens were tested under 5 conditions: intact, posterior bilateral fixation (L1-L5) only, LLIF-only, LLIF with unilateral fixation and LLIF with bilateral fixation. Non-destructive testing was performed on a universal testing machine (MTS Systems Corp) to produce flexion-extension, lateral-bending, and axial rotation using customized jigs and a pulley system to define a non-constraining load follower. Three-dimensional spine motion was recorded using a motion device (Optotrak).

Results are reported for the L3-L4 motion segment within the construct to allow comparison with previously published works of shorter constructs (1-2 segments). In all conditions, there was an observed decrease in ROM from intact in flexion/extension (31%-89% decrease), lateral bending (19%-78%), and axial rotation (37%-60%). At flexion/extension, the decreases were statistically significant (p<0.007) except for stand-alone LLIF. LLIF+unilateral had similar decreases in all planes as the LLIF+bilateral condition. The observed ROM within the 4-level construct was similar to previously reported results in 1-2 levels for stand-alone LLIF and LLIF+bilateral.

Surgeons may be concerned about the biomechanical stability of an approach utilizing stand-alone multilevel LLIF. Our results show that 4-level multilevel LLIF utilizing 26 mm cages demonstrated ROM comparable to short-segment LLIF. Stand-alone LLIF showed a decrease in ROM from the intact condition. The addition of posterior supplemental fixation resulted in an additional decrease in ROM. The results suggest that unilateral posterior fixation may be sufficient.


Orthopaedic Proceedings
Vol. 103-B, Issue SUPP_16 | Pages 36 - 36
1 Dec 2021
Hussain A Rohra S Hariharan K
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Abstract

Background

Tibiotalocalcaneal (TTC) fusion is indicated for severe arthritis, failed ankle arthroplasty, avascular necrosis of talus and as a salvage after failed ankle fixation. Patients in our study had complex deformities with 25 ankles having valgus deformities (range 50–8 degrees mean 27 degrees). 12 had varus deformities (range 50–10 degrees mean 26 degrees) 5 ankles an accurate measurement was not possible on retrospective images. 10 out of 42 procedures were done after failed previous surgeries and 8 out of 42 had talus AVN.

Methods

Retrospective case series of patients with hindfoot nails performed in our centre identified using NHS codes. Total of 41 patients with 42 nails identified with mean age of 64 years. Time to union noted from X-rays and any complications noted from the follow-up letters. Patients contacted via telephone to complete MOXFQ and VAS scores and asked if they would recommend the procedure to patients suffering similar conditions. 17 patients unable to fill scores (5 deceased, 4 nails removed, 2 cognitive impairment and 6 uncontactable)


Orthopaedic Proceedings
Vol. 103-B, Issue SUPP_2 | Pages 85 - 85
1 Mar 2021
Hussain A Poyser E Mehta H
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Abstract

Introduction

Local anaesthetic injections are regularly used for perioperative pain relief for shoulder arthroscopies. In our practice all shoulder arthroscopies were performed under general aneasthesia supplemented by perioperative subacromial local anaesthetic injections or landmark guided axillary nerve together with suprascapular nerve injections. We compared pain relief achieved with these two methods. We hypothesized that the selective nerve blocks would provide better post operative pain relief as described in literature.

Methods

We conducted a retrospective cohort study on two patient groups with 17 patients each. Group one patients received 20mls 50:50 mixture of 1% lignocaine and 0.5% chirocaine injections before and after start of procedure and group two patients received 20 mls of chirocaine around the axillary and suprascapular nerves. VAS scores were collected at 1 and 4 hours and analgesia taken during the first 24 hours was recorded.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XXXVII | Pages 323 - 323
1 Sep 2012
Li C Hussain A Joseph P Kamali A
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INTRODUCTION

One of the recent advances in the hard-on-hard hip arthroplasty is the development of a new material of diffusion hardened oxidised zirconium (DHOxZr). The DHOxZr material consists of a ceramic layer on the top surface which is supported by a thick oxygen diffusion hardened (DH) zone underneath. With the desired properties of metal substrate, ceramic surface and a gradient structure of the oxygen diffusion zone, the DHOxZr-on-DHOxZr bearing combination is expected to produce low wear and minimal metal ions. This can possibly address the concerns associated with metal hypersensitivity associated with metal on metal bearings and fracture risk associated with ceramics. The aim of this study was to evaluate the wear of DHOxZr-on-DHOxZr as a possible hard on hard bearing combination in hips.

METHODS

Three pairs of 50 mm DHOxZr prototype hip joint devices, each consisting of a DHOxZr modular head and a DHOxZr liner were wear tested in a ProSim hip joint simulator under standard testing conditions used by the Implant Development Centre (IDC), Smith & Nephew, Leamington Spa for 5 million cycles (Mc).

The flexion/extension was 30° and 15°. The internal/external rotation was ± 10°. The force was Paul-type stance phase loading, with a maximum load of 3 kN and a standard ISO swing phase load of 0.3 kN. The test frequency was 1 Hz. Gravimetric analysis was carried out at 0, 0.5, 1, 2, 3, 4 & 5 million cycles.

The lubricant was new born calf serum with 2 g/l sodium azide concentration diluted with de-ionised water to achieve average protein concentration of 20 g/l. Lubricant was changed every 0.25Mc during the first million cycles of the test and at every 0.33 Mc from 1 to 5Mc.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XXXVII | Pages 222 - 222
1 Sep 2012
Li C Hussain A Pamu J Kamali A
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INTRODUCTION

Hip wear simulator test results could be affected by many non-bearing related factors such as fixation surface conditions, equipment calibration and component set-up. In an effort to improve the accuracy, reliability and repeatability of hip simulator test, a quality management system has been established at the IDC hip tribology laboratory, which has been accredited by UKAS (United Kingdom Accreditation Service) in accordance with the recognised international standard ISO17025. This study demonstrates that under well-controlled laboratory and testing conditions, satisfactory repeatability can be achieved during hip simulator studies.

METHODS

Between 2008 to 2010, ten 50 mm Birmingham Hip Resurfacing (BHR) devices were tested by the IDC tribology laboratory using two ProSim hip wear simulators in three different tests (T1, T2 and T3). All tests were performed following the same IDC testing protocols at 1 Hz frequency for 5 million cycles (Mc) or until after a steady state was reached. Paul type stance phase loadings with a maximum load of 3 kN and a swing phase load of 0.3 kN was used. The flexion and extension angles were 30 and 15 degree. The internal/external rotation angel was ±10 degree. Wear was measured gravimetrically using an analytical balance (Mettler, Toledo xp504) with an accuracy of 0.1 mg.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XXXVII | Pages 524 - 524
1 Sep 2012
Prasad K Hussain A
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We hypothesised that an independent Notch Trial is essential on the same lines as other Component Trials-Femoral, Tibial and Patellar - in posterior stabilised total knee arthroplasty. Therefore we evolved Notch Trial to visually ascertain the adequacy of intercondylar resection and eliminate the possibility of femoral intercondylar fractures. We undertook a retrospective study to evaluate Notch Trial by the frequency of the need to remove osteophytes or file uneven surfaces in intercondylar resection by using the detachable box part of the trial femoral component, assess occurrence of distal femoral intercondylar fractures and demonstrate Notch Trial in posterior stabilised total knee replacement.

We studied 206 patients, 113 females and 93 males, who underwent consecutive primary posterior stabilised total knee replacements applying Notch Trial between 2000 and 2008 in a District General Hospital under our team. Outcome Measurements were 1) frequency of the need to remove osteophytes or file uneven surfaces in intercondylar resection and 2) occurrence of distal femoral intercondylar fractures intraoperatively or on postoperative radiographs. We had to remove the osteophytes and file the cut surfaces in 183 (88.88%) of patients after Notch Trial. We had no distal femoral intercondylar fractures intraoperatively or on postoperative radiographs.

Notch Trial allows the surgeon to directly visualise and ascertain the adequacy and precise fit of femoral notch cut with cam part of femoral component to ensure a press fit femoral component in condylar posterior cruciate substituting total knee replacement. Notch Trial prior to Femoral Component Trial effectively pre-empts intraoperative distal femoral intercondylar fractures. We recommend that Notch Trial should become part of the protocol for cruciate substituting total knee replacement and implants of all companies should have the option of a detachable box component for Notch Trial.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XXXVII | Pages 568 - 568
1 Sep 2012
Hussain A Kamali A Li C Ashton R
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INTRODUCTION

Whilst there is a great deal of research on hip implants, few studies have looked at implant orientation and the subsequent effect upon the wear performance of a hip resurfacing. This study aimed to measure implantation angles through radiographic analysis and linear wear for retrieved acetabular cups in order to investigate possible causal links between wear and implant orientation.

MATERIALS & METHODS

Seventy Birmingham Hip Resurfacing (Smith & Nephew, UK) cups with known time in vivo were analysed. Linear wear of retrieved cups were assessed using a Talyrond 290 roundness machine. Deviations from the characteristic manufactured profile, was identified as a region of wear. Polar measurements across the wear region were taken to determine wear. The linear wear rate (LWR) of a component was defined as the linear wear (μm) divided by the duration of the implant life in vivo (years). Cups which showed the wear crossing over the edge of the cup were classified as edge loaded (EL). For all non-edge loaded (NEL) cups, the wear area was within the bearing surface. Cup orientation angles were conducted for 31 cups. This was determined by superimposing BHR models of appropriate size, generated by CAD ProEngineer Wildfire 4, onto anterior-posterior x-rays. Anatomical landmarks and specific features of the BHR were used as points of reference to determine cup version and inclination angles.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XL | Pages 84 - 84
1 Sep 2012
Pamu J Hussain A Daniel J Kamali A Li C
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Introduction

Ion analysis has been used as one of the key indicators to assess the performance of MoM devices in patients. Modular devices, in particular having larger overall surface area (the stem and sleeve), and locking interfaces (head – bore, sleeve- taper and sleeve-bore, stem-taper surfaces) than other MoM devices are expected to release greater number of ions. Concerns have been expressed that the ion release at the taper junction might be a potential cause leading to the failure of the implant [Garbuz et al, 2010].

The aim of this study was to look into the wear and the associated ion release from the taper junction and the articulating surface of modular devices.

Method

For the first time a novel design has been used to isolate the taper junction on modular devices on the hip simulators in order to compare the wear at the taper junction and articulating surface. The taper junction has been isolated in a small gaiter, while the head and cup were contained in a large gaiter. CoCrMo sleeves having an offset of +8 mm have been used on 50 mm modular heads along with Ti6Al4V stems. The acetabular components were standard BHR cups. Three devices (Smith & Nephew, UK) have been tested with newborn calf serum as a lubricant (in the large gaiter) and also as the medium containing the taper junction (in the small gaiter). The serum samples from the articulating surface and taper junction were analysed using HR-ICPMS. The locking interfaces at the taper junction have been left intact throughout the duration of the test. Both the head and the cup have been tested under anatomical conditions using the standard implant development centre's (IDC) profile for 2 million cycles (Mc). The lubricant was newborn calf serum with 0.2% sodium azide diluted with de-ionised water to achieve protein concentration of 20 mg/ml. The flexion/extension was 30°/15° and the internal/external rotation was ±10°. The force was Paul-type stance phase loading with a maximum load of 3 kN and a standard ISO swing phase load of 0.3 kN. The frequency was 1 Hz, with an 8 hour stop after every 16 hours of testing.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XL | Pages 71 - 71
1 Sep 2012
Hussain A Kamali A Li C Pamu J
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Metal-on-Metal devices generate significantly lower volumetric wear than conventional total hip replacements. However, clinically some patients may suffer some form of laxity in their joints leading to subluxation of the joint, which in turn may cause edge loading of an implant thereby increasing the chances of failure due to higher than expected wear.

In this study, the effect of subluxation on MoM implant wear was investigated on a hip joint simulator.

Materials & Methods

Two groups of 44 mm MoM devices were tested, n=3 in each group. The devices were subjected to 1 and 2 mm of subluxation. The flexion/extension was 30° and 15° respectively, internal/external rotation was ±10°, and cup inclination was 35°. The force was Paul type stance phase loading with a maximum load of 3 kN, with ISO swing phase load of 0.3 kN, run at 1 Hz.

The test was carried out on a ProSim deep flexion & subluxation hip wear simulator (SimSol, UK). Rather than separating the head and the cup (microseparation), or reducing the swing phase load, this simulator is equipped with a novel mechanism to achieve translation of the head, while subjecting the devices to subluxation. During the swing phase, a controlled lateral force necessary for the translation of the head is applied by a cam mechanism, head retraction will then take place on heel strike.

The lubricant used was new born calf serum with 0.2 wt. % sodium azide concentration diluted with de-ionised water to achieve average protein concentration of 20 g/l. Lubricant was changed every 250k cycles. Gravimetric wear measurements have been taken at 0.25 & 0.5 Mc stages.

Results

Tests conducted with 1mm (Group 1) and 2mm (Group 2) subluxation significantly increased volumetric wear compared to standard hip simulator tests [1]. At 0.5 million cycles, group 1 and 2 produced an average volume loss of 4.38±0.98 mm3 (95% CL) and 7.07±1.64 mm3 (95% CL) respectively.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XXXVII | Pages 239 - 239
1 Sep 2012
Hussain A Hussain A Kamali A Li C Pamu J Ashton R
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INTRODUCTION

Analysis of retrieved ceramic components have shown areas of localized ‘stripe wear’, which have been attributed to joint laxity and/or impingement resulting in subluxation of the head, causing wear on the edge of the cup. Studies have been conducted into the effects of mild subluxation, however few in vitro tests have looked at severe subluxation. The aim of this study was to develop a more clinically relevant subluxation protocol.

MATERIALS & METHODS

Seven (Subluxation n=4; standard test n=3) of 36mm Biolox Forte (R3, Smith & Nephew) ceramic devices were tested for 0.5m cycles (mc). Two of the subluxed joints were further tested to 1 Mc. The devices were subjected to subluxation under standard testing conditions. The flex/ext was 30° and 15° respectively, with internal/external rotation of ±10°. The force was Paul type stance phase loading with a maximum load of 3 kN, and a standard ISO swing phase load of 0.3 kN at 1 Hz.

The test was conducted on a ProSim hip joint wear simulator (SimSol, UK). The simulator is equipped with a novel mechanism to achieve translation of the head, to achieve subluxation. During the ISO swing phase load of 0.3kN, a controlled lateral force required for the translation of the head is applied by a cam mechanism, head retraction then occurs during heel strike.

The lubricant used was new born calf serum diluted with de-ionised water to achieve average protein concentration of 20 g/l, with 0.2 wt % concentration NaN3, and changed every 250k cycles. Measurements have been taken at 0.5 & 1 mc stages.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XXV | Pages 96 - 96
1 Jun 2012
Hussain A
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Introduction

In vitro studies have shown that low clearance metal-on-metal hip joints have the potential of reducing wear during the running-in phase [1]. However, cementless acetabular cup relies on press fitting into the acetabulum, which can generate non-uniform compressive stresses and non-uniform in vivo cup deformation [2, 3]. This could then lead to equatorial contact, resulting in higher wear and friction for a MoM bearing with low clearance. To benefit from low wear generated by low clearance and at the same time to avoid the potential of head seizure and high frictional torque caused by cup deformation, a deflection compensation acetabular cup (DefCom) has been developed based on the Birmingham Hip Resurfacing (BHR) device. The articulating sphere of the DefCom cup provides a low clearance bearing area, whilst the non-articulating sphere maintains the standard BHR clearance. The aim of this study was to evaluate the wear performance of the novel DefCom hip joint using a hip wear simulator.

Materials and Methods

Five pairs of 50 mm DefCom devices were tested in a ProSim hip wear Simulator for 5 million cycles (MC) at a frequency of 1 Hz. The lubricant was new born calf serum with 0.2% sodium azide diluted with de-ionised water to achieve protein concentration of 20 mg/ml. The flexion/extension was 30° and 15° and the internal/external rotation was 10°. The force was Paul-type stance phase loading with a maximum load of 3 kN and a standard ISO swing phase load of 0.3 kN. Five standard 50 mm BHR devices were tested under the same testing conditions for comparison. Statistical analyses were performed at a 95% confidence level (CL) using the statistics function in Excel (Microsoft(r) Excel 2003).


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XXV | Pages 97 - 97
1 Jun 2012
Hussain A Packer K Li C Kamali A
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Introduction

All hip replacements depend upon good orientation and positioning to ensure that implants function well in vivo. Mal-orientated devices can lead to poor patient gait, poor range of motion, impingement, edge loading and high wear, which in turn may result in the premature failure of the implants.

Aim

To investigate the correlation between edge loading and wear on retrieved implants through linear wear analysis and radiographic examination of implants in vivo.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XXV | Pages 108 - 108
1 Jun 2012
Pamu J Kamali A Daniel J Hussain A Li C
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Introduction

Hip implant research has been carried out for decades using hip simulators to reflect situations in vivo. With regards to metal on metal (MoM) implant testing, it has been reported that there is no significant difference between the wear generated by various cobalt chromium (CoCr) microstructures. On the contrary, higher wear, metal ion levels and subsequent failures have been reported in heat treated (high carbon, low carbide) devices compared to as cast (high carbon, high carbide) devices in vivo. During testing, the bearing surfaces may be masked from the effect of microstructure on wear under fast and continuous cycles, while in vivo, the extensive range of kinetics and kinematics, stop/start motion, varying walking frequencies could break down the fluid film, resulting in a less favourable lubrication regime. The aims of this study were to develop a more physiologically relevant hip simulator test protocol, and investigate the effect of microstructure on wear.

Materials & Methods

Three pairs of 50mm as cast (AC) and four pairs of 50mm double heat treated (DHT) CoCr MoM devices were tested in a ProSim hip simulator. In order to determine the frequency for testing, Patients' activities have been monitored using a Step Activity Monitor (SAM) device. The data showed a relatively slower walking pace (frequency) than that used in the hip simulator studies. The new frequency, along with stop/start motion and various kinetics and kinematics profiles have been used in putting together a more physiologically relevant hip simulator test protocol. The lubricant used in this study was new born calf serum with 0.2 % (w/v) sodium azide concentration diluted with de-ionised water to achieve an average protein concentration of 20 g/l. Gravimetric measurements have been taken at 0.5, 1, 1.5 & 2 million cycle (Mc) stages and ion analysis has been carried out on the serum samples.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XIII | Pages 10 - 10
1 Apr 2012
Prasad K Dayanandam B Hussain A Myers K
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Aim

Thromboprophylaxis in total hip replacement (THR) and total knee replacement (TKR) remains controversial, conspicuous by absence of consensus. Because of protracted and variable mobilisation, there is an extended risk of Venous Thromboembolism (VTE). We hypothesised that a combination of low molecular weight heparin and miniwarfarin would minimise the initial and extended risk. Therefore we evolved a protocol of enoxaparin sodium 40 mgs for 5 days starting preoperatively and miniwarfarin 1-2mg for 6 weeks following surgery. We undertook a retrospective study of total hip and knee replacements in a District General Hospital between January 2000 and December 2005 to determine the effectiveness of the protocol.

Methods

We analysed the incidence of symptomatic VTE in 1307 patients, of who 681 underwent THR and 626 TKR. We evaluated the incidence of symptomatic DVT and PE between 0-6 weeks, 6 weeks-3months and 3-6 months following surgery.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_III | Pages 142 - 142
1 Feb 2012
Khalid M Kanagarajan K Jummani Z Hussain A Robinson D Walker R
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Introduction

Scaphoid fracture is the most common undiagnosed fracture. Occult scaphoid fractures occur in 20-25 percent of cases where the initial X-rays are negative. Currently, there is no consensus as to the most appropriate investigation to diagnose these occult frctures. At our institution MRI has been used for this purpose for over 3 years. We report on our experience and discuss the results.

Materials and methods

All patients with occult scaphoid fractures who underwent MRI scans over a 3 year period were included in the study. There was a total of 619 patients. From the original cohort 611 (98.7%) agreed to have a scan, 6 (0.97%) were claustrophobic and did not undergo the investigation and 2 (0.34%) refused an examination. 86 percent of the cases were less than 30 years of age. Imaging was performed on a one Tiesla Siemen's scanner using a dedicated wrist coil. Coronal 3mm T1 and STIR images were obtained using a 12cm field of view as standard. Average scanning time was 7 minutes.


Orthopaedic Proceedings
Vol. 93-B, Issue SUPP_II | Pages 221 - 221
1 May 2011
Hussain A Kamali A Li C Pamu J Daniel J
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Introduction: In vitro studies have shown that low clearance bearings have the potential to generate low wear. However, cementless acetabular cups are designed to be press fitted into the acetabulum, which could generate compressive stresses and non-uniform cup deformation during implantation. Deformation of the low clearance acetabular cups could also potentially lead to clamping or seizure of the joints and high frictional torque leading to implant failure. To obtain the benefit of low clearance and low wear, without compromising the tribological performance of the cup, a deflection compensation (DefCom) cup was designed. DefCom offers the benefits of low wear associated with low clearance components whilst reducing the risk of component seizure and high frictional torque due to component deformation.

Aim: The study was conducted in order to evaluate the tribological performance of a DefCom acetabular cup.

Materials and Methods: 50 mm diameter metal-on-metal DefCom hip resurfacing cups were used in this study. The components had an average clearance of 105±3 μm at the articulating sphere. Three of the cups were deformed plastically, along the ilial-ischeal column of the acetabulum. The degree of deformation was measured using the coordinate measuring machine, measuring the change in diameter of the cup in the direction of deformation. The cups were deformed on average by 65μm. The devices were tested in a ProSim hip wear Simulator for 5 million cycles. The lubricant was new born calf serum with 0.2% sodium azide diluted with de-ionised water to achieve protein concentration of 20 mg/ml. The flexion/extension was 30° and 15° with an internal/external rotation of ±10°. The force was Paul-type stance phase loading with a maximum load of 3 kN and a swing phase load of 0.3 kN, conducted at 1 Hz.

Results: The DefCom and deformed DefCom components showed a similar bi-phasic wear pattern to that of the BHR devices. Showing a period of ‘running in’ wear up to 1 Mc and then a reduced wear rate during the steady state phase from 1 Mc onwards. The DefCom devices produced a wear rate of 0.24 mm3/Mc, whilst the deformed DefCom joints produced a wear rate of 0.48 mm3/Mc for the running-in phase. Steady state wear was achieved for all joints after 1 Mc. The average steady state wear (1.0–5.0 Mc) rate for the DefCom joints was 0.12 mm3/Mc, with 0.14 mm3/Mc for the deformed joints joint. The wear rate for the non-deformed DefCom device is lower than that generated by the BHR, which were 0.72 mm3/Mc and 0.18 mm3/Mc for the running-in and steady state wear, respectively.

Conclusion: The study has shown that the DefCom acetabular cup has the potential to reduce the initial running-in wear by reducing the clearance at the contact area between the head and cup, whilst compensating for deformation that may occur during cup implantation.


Orthopaedic Proceedings
Vol. 93-B, Issue SUPP_I | Pages 57 - 57
1 Jan 2011
Prasad KSRK Hussain A
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Purpose: Axial alignment with restoration of mechanical axis is a major determinant of outcome in Total Knee Replacement.

Two perceived weaknesses of Intramedullary Referencing of Tibia are crucial:

difficulties in understanding where centre of medullary canal projects on the plateau to plan entry hole

in bowing of tibia, technical axis differs from anatomical axis, resulting in varus placement of tibial tray.

We evolved two technical pointers for optimal Tibial Intramedullary Referencing.

We undertook a retrospective study to analyse feasibility of our technique of Tibial Intramedullary Referencing.

Methods and Results: The study included 206 consecutive Total Knee Replacements between 2000 and 2008. Two – significant tibia vara and maluited tibial fracture- were excluded. Two techniques were used to avoid poor selection of entry hole and eccentric rod placement

Entry Drill Hole is made to a depth of 2–3 cm only and intramedullary rod is passed to find its own way into canal. This avoids tilted position of rod forced by a deeper drill hole and minimises tilted or wrongly sloped position of tibial tray.

Identification of Entry Point is facilitated by clearing soft tissue at tibial attachment of ACL over intercondylar eminence and confirmed by placing distal phalanx of surgeon’s thumb over bare area of anterior tibial plateau.

Entry point is usually at the tip of thumb.

We encountered no problems by our technique in Tibial Intramedullary Referencing in 204 Total Knee Replacements.

Conclusion: The two technical pointers help to overcome perceived drawbacks of Intramedullary Tibial Referencing.


Orthopaedic Proceedings
Vol. 93-B, Issue SUPP_I | Pages 56 - 56
1 Jan 2011
Hussain A Prasad KSRK
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Purpose: We hypothesised that independent Notch Trial is essential on same lines as other Component Trials – Femoral, Tibial and Patellar – in posterior stabilised total knee arthroplasty and evolved Notch Trial to visually ascertain adequacy of intercondylar resection and eliminate femoral intercondylar fractures.

We undertook a retrospective study to evaluate Notch Trial by the frequency of the need to remove osteophytes or file uneven surfaces in intercondylar resection by using detachable box part of trial femoral component and occurrence of distal femoral intercondylar fractures.

Methods & Results: We studied 206 patients, 113 females and 93 males, who underwent consecutive primary posterior stabilised total knee replacements applying Notch Trial between 2000 and 2008 under our team. Outcome Measurements were

frequency of osteophyte removal or filing uneven surfaces in intercondylar resection and

distal femoral intercondylar fractures intraoperatively or on postoperative radiographs.

We had to remove osteophytes and file cut surfaces in 183 (88.88%) patients after Notch Trial. We had no distal femoral intercondylar fractures.

Conclusions: Notch Trial allows the surgeon to directly visualise and ascertain adequacy and precise fit of femoral notch cut with cam part to ensure press fit femoral component in condylar posterior cruciate substituting total knee replacement. Notch Trial prior to Femoral Component Trial effectively pre-empts intraoperative distal femoral intercondylar fractures. We recommend that Notch Trial should become part of the protocol for cruciate substituting total knee replacement and implants of all companies should have the option of a detachable box component for Notch Trial.


Orthopaedic Proceedings
Vol. 92-B, Issue SUPP_IV | Pages 521 - 521
1 Oct 2010
Kamali A Hussain A Li C
Full Access

Introduction: Based on the clinical success of large head metal-on-metal (MoM) bearings technologies in the resurfacing arena, a multi-bearing acetabular system, known as R3 system, was developed by Smith & Nephew. The novel R3 system utilizes porous coated Ti-6-4 shells in which liners of crosslinked UHMWPE, ceramic, or as-cast CoCr liners can be placed. The as-cast CoCr metallurgy and microstructure is identical to the clinically successful Birmingham Hip Replacement (BHR) resurfacing system. The design and manufacturing aspects such as diametrical clearance, surface roughness, and spherical form are all identical for the two systems.

Aim: to evaluate the tribological performance of R3 devices as compared to that of standard BHR devices.

Materials and Methods: Five pairs of 46 mm MoM R3 devices (Smith & Nephew) and three pairs of 48 mm BHR devices (Smith & Nephew) were tested in a ProSim hip wear Simulator. The lubricant was new born calf serum with 0.2% sodium azide diluted with de-ionized water to achieve protein concentration of 20 g/l. The flexion/extension was 30° and 15° and the internal/external rotation was +/− 10°. The force was Paul-type stance phase loading with a maximum load of 3 kN and a standard ISO swing phase load of 0.3 kN. The frequency was 1 Hz.

One R3 joint and one BHR device were friction tested in a ProSim hip friction simulator at 0, 3 and 5 million cycles of wear testing. The test was conducted in new born calf serum with added carboxy methyl cellulose (CMC) to generate viscosities of 1 to 100 cP. The loading cycle was set at maximum loads of 2 kN and minimum load of 0.1 kN. The flexion/extension was 30° and 15°, and the frequency was 1 Hz.

Results and Discussions:

Friction: The coefficient of friction (COF) of the R3 joint varied from 0.08 to 0.14 depending on the viscosity of the serum and cycles of wear simulation test. Under physiologically relevant lubricant conditions (1, 3 and 10 cP), the COF for the R3 device tested was comparable to that of the standard BHR device.

Wear: The R3 devices generated typical characteristics of wear to the BHR devices, with a higher wear rate during the initial running in period (0 – 0.5 Mc) followed by a low steady state wear rate after 0.5 Mc. The average wear rate at 0.5 Mc was 1.86 mm3/Mc for the R3 and 1.80 mm3/Mc for the BHR devices. The wear rate during the steady state for the R3 and the BHR devices was reduced to 0.09 mm3/Mc and 0.12 mm3/Mc respectively. The difference in average wear rates between the BHR and R3 devices during the running in and steady states were not statistically significant (p > 0.05).

Conclusion: The test results presented in this study show that the tribological performances of the R3 and the BHR devices are comparable.