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The Bone & Joint Journal
Vol. 105-B, Issue 8 | Pages 837 - 838
1 Aug 2023
Kelly M McNally SA Dhesi JK


Orthopaedic Proceedings
Vol. 103-B, Issue SUPP_4 | Pages 46 - 46
1 Mar 2021
Valverde J Kabariti R Smith J Kelly M Murray J
Full Access

Pre-operative anaemia can present in up to 30% of elective arthroplasty patients. The presence of anaemia increases the risk of requiring blood transfusion post-operatively as well as acts as an independent risk factor for poor outcome such as prosthetic joint infection. Recent international consensus on this topic has recommended a specific care pathway for screening patients with pre-operative anaemia using a simple bedside Heaemacue finger-prick test to detect in a simple and cost-effective manner, and then allow treatment of preoperative anaemia. This pathway was therefore incorporated in our trust.

This was a retrospective study done at a single tertiary-referral arthroplasty centre. Our data collection included the Heamacue test results and formal haemoglobin levels if they were performed as well as compliance and costs of each of the tests for patients listed for an elective shoulder, hip and knee arthroplasty between September and December 2018. Medical records and demographics were also collected for these patients for subgroup analysis. Our exclusion criteria comprised patients listed for revision arthroplasty surgery.

87 patients were included in this study. Our compliance rate was 15%. The mean difference between a Haemacue test and a formal FBC result was only 17.6g/L suggesting that it has a reasonably high accuracy. With regards to costs, we found that a Haemacue test costs £2, compared to £7.50 for a full blood count and Haematinics combined. This gave an overall cost saving of £5.50 per patient. Extrapolation of this date locally for 2017 at our hospital, where 1575 primary joint arthroplasties were done, a cost saving of £8,662.5 could have been achieved. Within the UK using data extrapolated from the National Joint Registry a total of £1,102,205.5 (1,221,894 Euros) could have been saved.

The use of a single, Haemacue test to screen for pre-operative anaemia in elective arthroplasty patients is more cost effective compared to a formal full count and haematinics tests. However, we found that compliance with the care pathway is variable due to system limitations. This may be addressed through implementing changes to our electronic system in which patients are booked for surgery. We also noted a significant cost reduction if this pathway were to be used Nation-wide. Thus, we encourage other centres to consider the use of the Haemacue test pre-operatively in elective arthroplasty instead of formal full blood counts at the time of decision to treat with arthroplasty; this allows sufficient time for correction of pre-operative anaemia thus improving patient outcomes from arthroplasty.


Bone & Joint Open
Vol. 1, Issue 6 | Pages 261 - 266
12 Jun 2020
Fahy S Moore J Kelly M Flannery O Kenny P

Aims

Europe has found itself at the epicentre of the COVID-19 pandemic. Naturally, this has placed added strain onto healthcare systems internationally. It was feared that the impact of the COVID-19 pandemic could overrun the Irish healthcare system. As such, the Irish government opted to introduce a national lockdown on the 27 March 2020 in an attempt to stem the flow of admissions to hospitals. Similar lockdowns in the UK and New Zealand have resulted in reduced emergency department presentations and trauma admissions. The aim of this study is to assess the effect of the national lockdown on trauma presentations to a model-3 hospital in Dublin, Ireland.

Methods

A retrospective study was conducted. All emergency department presentations between 27 March 2019 to 27 April 2020 and 27 March 2020 to 27 April 2020 were cross-referenced against the National Integrated Medical Imaging System-Picture Archiving Communication System (NIMIS-PACS) radiology system to identify those with radiologically proven skeletal trauma. These patients were grouped according to sex, age, discharge outcome, mechanism of injury, and injury location.


The Bone & Joint Journal
Vol. 101-B, Issue 8 | Pages 1002 - 1008
1 Aug 2019
Al-Hourani K Stoddart M Khan U Riddick A Kelly M

Aims

Type IIIB open tibial fractures are devastating high-energy injuries. At initial debridement, the surgeon will often be faced with large bone fragments with tenuous, if any, soft-tissue attachments. Conventionally these are discarded to avoid infection. We aimed to determine if orthoplastic reconstruction using mechanically relevant devitalized bone (ORDB) was associated with an increased infection rate in type IIIB open tibial shaft fractures.

Patient and Methods

This was a consecutive cohort study of 113 patients, who had sustained type IIIB fractures of the tibia following blunt trauma, over a four-year period in a level 1 trauma centre. The median age was 44.3 years (interquartile range (IQR) 28.1 to 65.9) with a median follow-up of 1.7 years (IQR 1.2 to 2.1). There were 73 male patients and 40 female patients. The primary outcome measures were deep infection rate and number of operations. The secondary outcomes were nonunion and flap failure.


Orthopaedic Proceedings
Vol. 99-B, Issue SUPP_12 | Pages 42 - 42
1 Jun 2017
Della Valle C Fillingham Y Bohl D Kelly M Hall D Pourzal R Jacobs J
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Recently, corrosion at the head-neck junction in metal-on-polyethylene bearing total hip arthroplasty (THA) has been recognized as a cause of adverse local tissue reactions (ALTR). Serum metal levels have been advocated as a tool for the diagnosis of ALTR, however no prior studies have specifically examined their utility. The purpose of this study was to determine the optimal cut-off values for serum cobalt and chromium in diagnosing ALTR after metal-on-polyethylene bearing THA.

We reviewed 447 consecutive patients with serum metal levels tested at our institution and identified 62 with a metal-on-polyethylene bearing who had axial imaging or underwent reoperation to confirm the presence or absence of ALTR. Receiver operating characteristic curves were produced to identify cut-off thresholds to optimize sensitivity and diagnostic test performance was characterized.

42 Of the 62 patients (66%) were positive for an ALTR. The best test for the diagnosis of ALTR was the serum cobalt level (area under the curve [AUC]=99%). A threshold cut-off of ≥ 1.0 ng/ml had a sensitivity of 100%, specificity of 90%, positive predictive value (PPV) of 96%, and negative predictive value (NPV) of 100%. Serum chromium levels were also diagnostic (AUC=87%). A threshold cut-off of ≥ 0.15 ng/ml had a sensitivity of 100%, specificity of 50%, PPV of 81%, and NPV of 100%. Finally, serum cobalt to chromium ratio was also helpful for diagnosis (AUC=90%). A threshold cut-off of 1.4 for the cobalt to chromium ratio offered a sensitivity of 93%, specificity of 70%, PPV of 87%, and NPV of 82%.

Measurement of serum cobalt with a threshold value of 1.0 ng/ml in our experience is the best test for identifying the presence of ALTR in patients with a metal-on-polyethylene THA. Measurement of chromium and the ratio of cobalt to chromium are also of value.


Orthopaedic Proceedings
Vol. 99-B, Issue SUPP_8 | Pages 92 - 92
1 Apr 2017
Smith J Halliday R Aquilina A Hull P Kelly M
Full Access

Background

Hip fracture care has evolved, largely due to standardisation of practice, measurement of outcomes and the introduction of the Best Practice Tariff, leading to the sustained improvements documented by the National Hip Fracture Database (NHFD). The treatment of distal femoral fractures in this population has not had the same emphasis. This study defines the epidemiology, current practice and outcomes of distal femoral fractures in four English centres.

Methods

105 patients aged 50 years or greater with a distal femoral fracture, presenting to four UK major trauma centres between October 2010 and September 2011 were identified. Data was collected using an adapted NHFD data collection tool via retrospective case note and radiograph review. Local ethics approval was obtained.


Orthopaedic Proceedings
Vol. 97-B, Issue SUPP_7 | Pages 22 - 22
1 May 2015
Mathews J Ward J Chapman T Khan U Kelly M
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Grade III Open fractures of the tibia represent a serious injury. It is recognised that combined management of these cases by experienced orthopaedic and plastic surgeons improves outcomes. Previous studies have not considered the timing of definitive soft tissue cover in relation to the definitive orthopaedic management. We reviewed medical notes of 73 patients with 74 Grade III Open tibia fractures (minimum 1 year follow up), to compare deep infection rates in patients who had a) a single-stage definitive fixation and soft tissue coverage vs. those who had separate operations, and b) those who had definitive treatment completed in < 72 hours vs. > 72 hours.

Of subjects that underwent definitive fixation and coverage in a single procedure, 4.2% developed deep infections, compared with 34.6 % deep infection(p<0.001) in those who underwent definitive treatment at separate operations. Of patients who had definitive treatment completed in < 72-hours, 20.0% developed deep infections a compared with 12.2%(p=0.4919) in the >72-hour group.

Patients with Gustilo III open tibial fractures have lower rates of deep infection if definitive fixation and coverage are performed in a single-stage procedure. Emphasis should be placed on timely transfer to a specialist centre, aiming for a single-stage combined orthoplastic surgery.


Orthopaedic Proceedings
Vol. 97-B, Issue SUPP_7 | Pages 26 - 26
1 May 2015
Tucker D Surup T Petersik A Kelly M
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Anterior positioning of a cephomedullary nail in the distal femur occurs in up to 88% of cases. This is considered to occur because of a mismatch between the radius of curvature of the femur and that of available implants. The hypothesis for this study was that the relative thicknesses of the cortices of the femur (referenced off the linea aspera) change with age and determine the final position of intramedullary implants.

This study used the data from CT scans undertaken as part of routine clinical practice in 919 patients with intact left femora (median age 66 years, 484 male and 435 female). The linea aspera and transverse intervals were plotted on a template femur between 25% – 60% femoral bone length (5% increments) and mapped automatically to all individual femora in the database with measurements taken in the plane of the linea aspera.

The linea aspera was found to be internally rotated as compared to the sagittal plane referenced off the posterior femoral condyles. An age related change in the posterior/anterior cortical thickness ratio was demonstrated. The >80 year old cohort shows a significantly disproportional posterior/anterior ratio increase of 70.0% from 25–50% bone length as compared to 48.1% for the <40 year old cohort (p<0.05).

This study has shown that assessment in the sagittal plane may be inaccurate because of rotational changes in the linea aspera. The centering influence of the corticies is lost with age with a relative thinning of the anterior cortex and thickening of the posterior cortex moving distally in the femur. This has a direct influence on the positioning of intramedullary implants explaining the preponderance of anterior malpositioning of intramedullary implants in the elderly.


Orthopaedic Proceedings
Vol. 97-B, Issue SUPP_3 | Pages 16 - 16
1 Apr 2015
Marsh A Crighton E Yapp L Kelly M Jones B Meek R
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Successful treatment of periprosthetic joint infection involves surgical intervention and identification of infecting organisms to enable targeted antibiotic therapy. Current guidelines recommend intra-operative culture sampling to include at least 4 tissue samples and for each sample to be taken with a separate instrument.

We aimed to review current revision arthroplasty practice for Greater Glasgow, specifically comparing intra-operative sampling technique for infected revision cases with these guidelines.

We reviewed the clinical notes of all patients undergoing lower limb revision arthroplasty procedures in Greater Glasgow Hospitals (WIG, GRI, SGH) from July 2013 to August 2014. Demographics of all cases were collected. For revision procedures performed for infection we recorded details of intraoperative samples taken (number, type and sampling technique) and time for samples to reach the laboratory. Results of microbiology cultures were reviewed.

Two hundred and fifty five revision arthroplasty procedures (152 hips, 103 knees) were performed in the 12 month study period. Of these 57 (22%) were infected cases (28 hips, 29 knees). These cases were treated by 14 arthroplasty surgeons with a median number of 3 infected cases managed per surgeon (range 1–11). 58% of cases had the recommended number of tissue samples taken. The median number of microbiology samples collected was 4 (range 1–14). Most procedures (91%) had no documentation of whether separate instruments were used for sampling. Number of tissue samples taken (≥4, p=0.01), time to lab (<24 hours, p=0.03) were significantly associated with positive culture results.

In Greater Glasgow, a large number of surgeons manage infected arthroplasty cases with variability in intra-operative sampling techniques. Sample collection adheres to guideline recommendations in 58% cases. Adhering to guideline standards increases the likelihood of positive tissue cultures. Implementation of a standardised approach to intra-operative sampling for infected cases may improve patient management.


Orthopaedic Proceedings
Vol. 96-B, Issue SUPP_19 | Pages 45 - 45
1 Dec 2014
Tucker D Surup T Petersik A Kelly M
Full Access

Purpose:

Anterior positioning of a cephomedullary nail (CMN) in the distal femur occurs in up to 88% of cases. Conventionally, this is considered to occur because of a mismatch between the radius of curvature (ROC) of the femur and that of available implants. The hypothesis for this study was that the relative thicknesses of the cortices of the femur, particularly the posterior cortex are important in determining the final position of an intramedullary implant and that the posterior cortical thickness corresponds to the linea aspera anatomically. The aim was to determine if these measurements changed with age.

Method:

This study used the data from CT scans undertaken as part of routine clinical practice in 919 patients with intact left femora (median age 66 years, range 20–93 years; 484 male and 435 female). The linea aspera was defined manually on the template bone by consensus between two orthopaedic surgeons and two anatomists. The length of the femur was measured from the tip of the greater trochanter proximally to the intercondylar notch distally. Transverse intervals were plotted on the femur between 25%–60% femoral bone length (5% increments). The linea aspera was then defined at each interval on the template bone and mapped automatically to all individual femora in the database.


Orthopaedic Proceedings
Vol. 95-B, Issue SUPP_31 | Pages 45 - 45
1 Aug 2013
Chambers M Diffin C Campton L Roberts J Kelly M
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A tip-apex distance (TAD) greater than 25 mm is a strong predictor of screw cut-out in patients with intertrochanteric femoral fracture treated with a dynamic hip screw (DHS). We aim to show you a simple and reliable way to check this.

By calculating the sum of the distance from the tip of the screw to the apex of the femoral head on anteroposterior and lateral views the TAD is found. X-rays often have magnification errors and therefore measuring tools in digital x-ray systems will be inaccurate. The original method of calculating the TAD uses the known diameter of the screw to avoid magnification errors.

We found that due to the no-cylindrical shape of the screw shaft there is potential of an inaccurate measurement. By using the distance across the highest points of the thread a more accurate TAD can be calculated.

The distance across the highest points of the threads in all three of the most commonly used DHSs in the UK is 13 mm. If the measured distance from the tip of the screw to the apex of the femoral head in both the anteroposterior and lateral views is less than the measured distance across of the treaded diameter of the screw then the surgeon knows the TAD is less than 26 mm. This method can be used intraoperatively to check the TAD by looking at the fluoroscopy images in these two views.


Orthopaedic Proceedings
Vol. 95-B, Issue SUPP_30 | Pages 20 - 20
1 Aug 2013
Elias-Jones C Reilly J Kerr S Meek R Patil S Kelly M Campton L McInnes I Millar N
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Femoroacetabular impingement (FAI) is a significant cause of osteoarthritis in young active individuals but the pathophysiology remains unclear. Increasing mechanistic studies point toward an inflammatory component in OA. This study aimed to characterise inflammatory cell subtypes in FAI by exploring the phenotype and quantification of inflammatory cells in FAI versus OA samples.

Ten samples of labrum were obtained from patients with FAI (confirmed pathology) during open osteochondroplasty or hip arthroscopy. Control samples of labrum were collected from five patients with osteoarthritis undergoing total hip arthroplasty. Labral biopsies were evaluated immunohistochemically by quantifying the presence of macrophages (CD68 and CD202), T cells (CD3), mast cells (mast cell tryptase) and vascular endothelium (CD34).

Labral biopsies obtained from patients with FAI exhibited significantly greater macrophage, mast cell and vascular endothelium expression compared to control samples. The most significant difference was noted in macrophage expression (p<0.01). Further sub typing of macrophages in FAI using CD202 tissue marker revealed and M2 phenotype suggesting that these cells are involved in a regenerate versus a degenerate process. There was a modest but significant correlation between mast cells and CD34 expression (r=0.4, p<0.05) in FAI samples.

We provide evidence for an inflammatory cell infiltrate in femoroacetabular impingement. In particular, we demonstrate significant infiltration of mast cells and macrophages suggesting a role for innate immune pathways in the events that mediate hip impingement. Further mechanistic studies to evaluate the net contribution and hence therapeutic utility of these cellular lineages and their downstream processes may reveal novel therapeutic approaches to the management of early hip impingement.


Orthopaedic Proceedings
Vol. 95-B, Issue SUPP_10 | Pages 9 - 9
1 Feb 2013
Elias-Jones C Reilly J Kerr S Meek R Patil S Kelly M Campton L McInnes I Millar N
Full Access

Femoroacetabular impingement (FAI) is a significant cause of osteoarthritis in young active individuals but the pathophysiology remains unclear. Increasing mechanistic studies point toward an inflammatory component in OA. This study aimed to characterise inflammatory cell subtypes in FAI by exploring the phenotype and quantification of inflammatory cells in FAI versus OA samples.

Ten samples of labrum were obtained from patients with FAI (confirmed pathology) during open osteochondroplasty or hip arthroscopy. Control samples of labrum were collected from five patients with osteoarthritis undergoing total hip arthroplasty. Labral biopsies were evaluated immunohistochemically by quantifying the presence of macrophages (CD68 and CD202), T cells (CD3), mast cells (mast cell tryptase) and vascular endothelium (CD34).

Labral biopsies obtained from patients with FAI exhibited significantly greater macrophage, mast cell and vascular endothelium expression compared to control samples. The most significant difference was noted in macrophage expression (p<0.01). Further sub typing of macrophages in FAI using CD202 tissue marker revealed and M2 phenotype suggesting that these cells are involved in a regenerate versus a degenerate process. There was a modest but significant correlation between mast cells and CD34 expression (r=0.4, p<0.05) in FAI samples.

We provide evidence for an inflammatory cell infiltrate in femoroacetabular impingement. In particular, we demonstrate significant infiltration of mast cells and macrophages suggesting a role for innate immune pathways in the events that mediate hip impingement. Further mechanistic studies to evaluate the net contribution and hence therapeutic utility of these cellular lineages and their downstream processes may reveal novel therapeutic approaches to the management of early hip impingement.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XXXVII | Pages 50 - 50
1 Sep 2012
Maempel J Ward A Chesser T Kelly M
Full Access

Background

Tightrope fixation has been suggested as an alternative to screw stabilisation for distal tibiofibular joint diastasis that provides stability but avoids the problems of rigid screws across the joint. Recent case series (of 6 and 16 patients) have however, reported soft tissue problems and infections in 19–33% of patients. This study aims to review treatment and complications of distal tibiofibular diastasis fixation in our unit with the use of Tightrope or diastasis screws.

Methods

Retrospective review of all patients undergoing primary ankle fixation between May 2008 and October 2009. Exclusions included revision procedures, or ankle fixation prior to the current fracture. Those undergoing Tightrope or diastasis screw fixation were studied for any complications or further procedures. Clinical records and XRAYs were reviewed, family practitioners of the patients were contacted and any consultations for ankle related problems noted.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XXXIII | Pages 17 - 17
1 Jul 2012
Murray O Lee S Mckenna R Kelly M Roberts J
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Early failure of metal-on-metal (MoM) total hip replacements (THR) is now well established. We review 93 consecutive patients with CPT¯ stems MoM THR. Our series demonstrates a new mechanism of failure, which may be implant combination specific.

Between January 2005 and June 2009, 93 consecutive MoM total hip replacements were preformed using CPT stems by 3 surgeons at our unit. 73 CPT¯ stems, Metasul¯ Large Diameter Heads (LDH) with Durom¯ acetabulae and 20 CPT¯ stems, Metasul¯ 28mm diameter heads in Allofit¯ shells (zimmer). Clinical outcomes were collected prospectively before surgery, at 3 months, 1 year, 2 years, 3 years, and at 5 years post surgery. Revision for any cause was taken as the primary endpoint and the roentgenograms and explanted prostheses were analyzed for failure patterns.

In the LDH/Durom¯ group a total of 13 (18%) patients required revision (figs. 1) at a median of 35 months (range 6-44). 6 (8%) for periprosthetic fracture. All 6 periprostethic fractures were associated with minimal or no trauma and all had ALVAL identified histologically.

To date there have been no failures in the CPT¯/28mm head Allofit¯ group. Several failures demonstrated bone loss in Gruen zones 8 ± 9 ± 10 (fig. 2).

We demonstrate an unacceptably high rate of failure in CPT¯ MoM LDH hip replacements, with a high failure secondary to periprosthetic fracture and postulate a mechanism associated with local toxicity to metal ions. We strongly advise against this combination of prosthesis.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XVII | Pages 18 - 18
1 May 2012
McCoy S Chambers M Gray A Kelly M Rana B Roberts J
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Introduction

The Western Infirmary/Gartnavel General Hospital orthopaedic department is geographically located next to the Beatson Oncology Centre, a specialist regional oncology unit. Pathological femoral fractures are the commonest reason for surgical intervention in patients referred from the Beatson and we have used them as a model to establish the demographic data, referral patterns, treatment results, and survival characteristics in such a group of patients.

Methods

We have collected prospective data for the last 4 years on referrals from patients under the care of oncology services.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_II | Pages 76 - 76
1 Feb 2012
Walmsley P Kelly M Robb J Annan I Porter D
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Supracondylar fractures of the humerus have historically been treated as an emergency case and operated on at the earliest opportunity. We undertook a study to examine whether surgical timing affects the need for open reduction or peri-operative complications in the type III injuries.

Between August 1995 and August 2004, 534 patients presented and were referred to our unit with these fractures. Those with closed, type III injuries without vascular compromise were selected (171 patients). These were divided into 2 groups: those undergoing surgery less than 8 hours from presentation (126 patients) and those undergoing surgery more than 8 hours from presentation (45 patients).

The two major differences between the two groups were: the delayed group were more likely to undergo open reduction (33.3% v 11.2%, p<0.05) and the mean length of the surgical procedure was increased (105.1 minutes v 69.2 minutes, p<0.05). Delay in treatment of the type III supracondylar fractures is associated with an increased need for open reduction and a longer procedure. We would recommend treating these injuries at the earliest opportunity.


Orthopaedic Proceedings
Vol. 93-B, Issue SUPP_I | Pages 64 - 64
1 Jan 2011
Schmied M Kelly M Ballantyne J Brenkel I
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Hip and knee arthroplasty account for over 95 000 hospital days annually in Scotland. The gross cost of over £81 million can be reduced by £10 million by decreasing length of stay by just one day per patient.

We performed a retrospective analysis of the data from the Scottish Arthroplasty Project (SAP). We specifically looked at length of stay in patients undergoing total hip and knee replacements between 1996 and 2007. We analysed the data on over

91000 total hip and knee replacements. In addition we looked at the influence of age, volume and day of admission on the 2007 data

Over the 11 year period there were significant variations in improved length of stay across the health boards. For the 2007 data, we found that patients treated in boards with high patient volume had shorter hospital stays. Admission policy and age of the patients affected the length of stay it did not account for the large differences between health boards.

The data from the Scottish Arthroplasty Project shows that higher surgical volume correlates with reduced length of stay in arthroplasty patients. The reasons for this are likely to be multifactorial but generalisable and need to be examined more closely with another study.


Orthopaedic Proceedings
Vol. 90-B, Issue SUPP_III | Pages 564 - 564
1 Aug 2008
Chambers M Roberts J Kelly M
Full Access

With the advent of the advancement of manufacturing technologies hip resurfacing (HR) has become a serious option for a younger patient with osteoarthritis of the hip. The operation is technically demanding and correct placement of the femoral component is the critical step.

We hypothesised that with computer navigation we can improve the placement of the femoral component and restore the biomechanics of the hip joint compared to currently available mechanical jigs.

We compared the radiological results and operation time in 8 patients undergoing computer navigated hip resurfacings (cnHR) to 30 patients undergoing mechanical jig hip resurfacings (jigHR).

Our results showed the average angle of the central pin in the femoral neck in the jigHR group was 141 degrees on the AP radiographs (range 131 to 154 degrees) and 6 degrees antevertion (range 0 to 8 degrees) on the lateral radiographs compared with 135 degrees (range 134 to 138 degrees)and 5 degrees (range 3 to 8 degrees)in the cnHR group. The position of the central pin in the neck immediately below the head was off-centre in the jigHR group on average by 4mm in both AP and lateral radiographs and never more than 2mm in the cnHR group in either view. Offset was increased on average 5mm in the jigHR group and decreased on average by 3mm in the cnHR group. The average operation time was 107 minutes in the jigHR group and 110 minutes in the cnHR group.

We conclude that despite our relatively small sample group we have showed computer navigation gives consistent optimum positioning of the femoral component and improves the biomechanics of the hip. This was without increasing operating time.


Orthopaedic Proceedings
Vol. 90-B, Issue SUPP_II | Pages 384 - 385
1 Jul 2008
Huber C Kelly M Lautenschlager T Noble B Simpson H
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Over 1 million fractures occur each year in the UK. Approximately 5-10% of these fractures have problems with healing. The treatments used for these patients often have a poor outcome and are associated with increased morbidity and disability. Application of synthetic peptides such as thrombin degradation peptide (TP508) has been shown to accelerate fracture repair in a closed rat femoral fracture model. Controlled release of TP508 using microspheres has been shown to enhance repair of articular cartilage defects and stimulate bone formation in segmental defects in rabbits. The aim of this study was to determine whether TP508 could bring about healing in an established fracture non-union model.

A validated rat model of fracture non-union was used. The model was created and left for 8 weeks in order to represent a clinically equivalent model of a non union of a fracture. Rats were randomised into two treatment groups receiving 10microg and 1microg doses of TP508 diluted in 50microL of microspheres and delivered directly to the non union site using percutaneous injection 8 weeks after surgery. The control group received no treatment. At 16 weeks post-surgery, osseous bridging was assessed both radiographically and histologically.

Radiographically there was no difference between the control and two treatment groups. However, histomor-phometric analysis demonstrated that bone formation increased by 43.9% in animals that received high dose of TP508 compared to the control animals. The analysis also indicated that administration of the low dose of TP508 increased the amount of bone formation compared to the control by 9.9 %.

Administration of TP508 has been shown to enhance healing of segmental defects in both critically and noncritically sized defects. However, in our model which is an established fracture non-union model, TP508 did not manage to achieve full osseous union. It has been suggested that the action of this peptide is concentration and environment dependent possibly indicating that TP508 might be less effective when administered in a chronic situation such as that associated with the established non-union fracture. However, even in this sub-optimal situation an increased amount of bone formation was observed.