Recent studies have shown that bone mineral distribution is more heterogeneous in bone tissue from an animal model of osteoporosis and osteoporotic human vertebral trabeculae. These tissue alterations may play a role in bone fragility seen in osteoporosis, albeit that they are not detectable by current diagnostic techniques (dual-energy X-ray absorptiometry, DXA). Type II Diabetes Mellitus (T2DM) also increases a patient's fracture risk beyond what can be explained or diagnosed by DXA, and is associated with impaired bone cell function, compromised collagen structure and reduced mechanical properties. However, it is not currently known whether osteoporosis or T2DM leads to an increased mineral heterogeneity in the femoral head of humans, a common osteoporotic fracture site. In this study, we examine bone microarchitecture, mineralisation and mechanical properties of trabecular bone from osteoarthritic, diabetic and osteoporotic patients. We report that while osteoporotic trabecular bone has significantly deteriorated mechanical properties and microarchitecture compared to the other groups, there is also a significant increase in mean mineral content. Moreover, the heterogeneity of the mineral content in osteoporotic bone is significantly higher than osteoarthritic (+35%) and diabetic (+13%) groups. We propose that the compromised architecture following bone loss at the onset of osteoporosis alters the mechanical environment, which initiates compensatory changes in mineral content. We show for the first time that trabecular bone mineralisation is significantly more heterogeneous (+20%) in T2DM compared to osteoarthritic controls. Interestingly, bone microarchitecture and mechanical properties are not significantly different between diabetic and osteoarthritic groups despite this increase in mineral heterogeneity.

Epidemiological studies have shown that accumulated mechanical stress is a risk factor for the development of osteoarthritis (OA). This debilitating progressive clinical condition affects a broad spectrum of patients and will ultimately lead to definitive arthroplasty surgery as the endpoint treatment option in many cases. The aim of this study is to establish a graded murine model of OA by medial meniscotibial destabilisation of the knee joint and in phase two, to investigate the migration and engraftment of radioisotope labeled mesenchymal stem cells (MSCs) at varying points of disease progression. The first phase of the study was to establish the murine model, an Irish first. All procedures were performed aseptically under general anaesthesia via a midline medial parapatellar approach on a murine fracture table. Microsurgical dissection was performed through necropsy analysed layers to the joint space and the meniscotibial ligament identified and transected. Validated histopathological analysis was performed at two, four, eight and twelve weeks postoperatively. The results showed a gradation of OA changes from mild unicondylar changes at two weeks, moderate unicompartmental change at four, severe unicompartmental change at eight and severe bicompartmental change at twelve weeks post-operatively. In vivo Bazooka-Single Photon Emission Computed Tomography (SPECT) (Phase 2) imaging studies are currently ongoing following the model establishment.

Prenatal androgen exposure has important organising effects on brain development and influences future behavioural patterns. Second to fourth digit ratio (2D:4D) is a marker for prenatal androgen exposure and as such is a sexually dimorphic trait. Smaller, more masculine second digit (index finger) to fourth digit (ring finger) ratio’s are associated with higher exposure to prenatal testosterone levels or greater sensitivity to androgens, or both. People with smaller finger ratios, a longer fourth finger than second finger, have been shown to be more successful in competitive sports, exhibit increased visuo-spatial ability, more fertile and are perceived as being more masculine and dominant by female observers. Smaller ratios have also been associated with an increased propensity to engage in aggressive behaviour. We examined the relationship between Boxer’s fractures, a traditional injury of aggression and finger length ratio.

We reviewed 1123 patient records and/or hand x rays over a seven month time frame showing 123 fifth metacarpal (Boxer’s) fractures. We then measured, using recorded radiological data, the distance in millimetres from the base of the proximal phalanx to the tip of the distal phalanx for the second, third and fourth fingers. We also recorded sex, side of injury, site of injury and mode of injury.

One hundred and twenty three Boxer’s fractures were found over a seven month time period, 110 male and 13 female; 67.27% were right sided. The average age was 27.6 yrs ±14.2. The average finger length ratio (proximal phalanx to distal phalanx) for males was 0.9 and for females was 0.94. Both ratios were smaller than the published normal digit ratio for the general population.

Smaller second digit to fourth digit ratios are positively associated with persons presenting with fifth metacarpal fractures, thereby indicating increased aggressive tendancies independently of gender

Introduction: Finger length ratio (2d:4d) is a sexually dimorphic trait. Smaller, more masculine second digit (index finger) to fourth digit (ring finger) ratio’s are associated with higher exposure to prenatal testosterone levels or greater sensitivity to androgens, or both. People with smaller finger ratios are perceived as being more masculine and dominant by female observers. Smaller ratios have also been associated with an increased propensity to engage in aggressive behaviour. We examined the relationship between Boxer’s fractures, a traditional injury of aggression and finger length ratio.

Methods: We reviewed 1123 patient records and/or hand x-rays over a seven month time frame showing 123 fifth metacarpal (Boxer’s) fractures. We then measured, using recorded radiological data, the distance in millimetres from the base of the proximal phalanx to the tip of the distal phalanx for the second, third and fourth fingers. We also recorded sex, side of injury, site of injury and mode of injury.

Results: 123 Boxer’s fractures were found over a seven month time period, 110 male and 13 female. 67.27% were right sided. The average age was 27.6 yrs ±14.2. The average finger length ratio (proximal phalanx to distal phalanx) for males was 0.9 and for females was 0.94.

Conclusion: Smaller second digit to fourth digit ratios are positively associated with persons presenting with fifth metacarpal fractures, thereby indicating increased aggressive tendancies independently of gender.

Over the past four decades, internal fixation has continued to gain popularity as a method for treating fractures because of significant improvements in both implant design and materials. This biomechanical study compares the compressive forces generated by a conventional 4.5 AO/ASIF cortical screw lag screw with a differential pitch cortical compression screw in a simulated fracture model using whole bone composite femur. The differential pitch screw investigated in this study generates 82% of the compression generated by a conventional 4.5mm AO/ASIF cortical screw. Proving compression in diaphyseal fractures is achievable using a differential pitch screw. Sufficient compression is generated to allow osteosynthesis using a plate to be preformed independent of the lag screw positioning. It is thus advantageous over the traditional compromise that arises when exposure to the fracture site is limited, of either incorporating the lag screw into the plate of choosing a non-optimal plate or screw position. It is proposed as an adjunct to the internal fixation of long bone fractures and not a single fixation device.

Introduction: Uncemented total hip arthroplasty has evolved significantly over the past two decades. During this period many implants with different shapes, designs and coatings have developed and are being used with variable results. We present a series of 100 uncemented hip arthroplasties using the Duraloc 100 series cup and Corail stems which have been in use at Merlin Park for the past 5 years and 1 year respectively. The CORAIL stem first introduced in 1986 has a triplanar wedge design for optimal metaphyseal fixation. The prosthesis is pointed in its distal part to allow centering in the medullary canal without cortical locking. The titanium stem is fully coated with a 150 micron thick layer of hydroyapatite. According to the Norwegian arthroplasty register the stem has 99.5% survival at 4.5 years (Havelin L1, Espheaug B, Vollset SE, Engesaeter LB).

The Duraloc 100 series acetabular cups are hemispherical, porous-coated implants that are press fitted to a cavity reamed 2mm smaller than the cup diameter.

Material and methods: Between January 2002 and September 2003 we carried out 100 uncemented THRs in 65 males and 35 female patients. Patients were deemed fit for uncemented hip replacement if they had good bone stock and had no co-morbid condition which might compromise bone quality. Preoperative work up was carried out to exclude any generalised diseases that might compromise bone quality, including bone density measurements where appropriate. Baseline WOMAC scores and Harris hip scores were performed pre-operatively and at latest follow up. Operative details were recorded along with post-operative complications. Patients were followed up clinically and radiologically for a period of 6 to 26 months.

Results: There were 65 male patients and 35 female patients. Average age in men was 62.5 years (range 40 to 85 years) and in women was 65 years (range 48 to 86 years). Four patients had rheumatoid arthritis, the rest had osteoarthritis. The average post-op hospital stay was 12 days. The mean WOMAC score increased from 45 pre-op to 87 at the latest follow up. The average Harris hip score also increased from 52 pre-op to 92 at latest follow up.

All procedures were either performed or directly supervised by the senior authors. Operations were performed through an antero-lateral approach, the femur was prepared first and a trial reamer was left in the femoral canal to minimise blood loss while the acetabulum was reamed. The average duration of surgery was 65 minutes (range 45 to 100 mins) and average intra-operative blood loss was 300mls (range 125 to 750mls). Intra-operative complications included 2 proximal femur stable split fractures, they were identified on table and fixed with circlage cables. Patients were allowed to mobilise partial weight bearing as tolerated. Complications included 4 deep venous thromboses, three superficial wound infections, one respiratory tract infection and one myocardial infarction. At the latest follow up there are no dislocations, no deep infections and no loosening of the cup or the stem.

Discussion: When considering new implants and techniques in arthroplasty long term outcome of studies are necessary before any firm conclusions can be drawn regarding ultimate efficacy. This study however confirms that uncemented THRs using Duraloc cups and Corail stems is safe, involves minimal blood loss and gives good short term results. As there is no cement used, the duration of surgery is at least 15 to 20 mins less than an average cemented THR, which may be important when access to theatre is limited. The procedure is easy to learn and has well designed instrumentation. While there is no substitute for long term studies we feel that these early results are encouraging and justify continued work with the procedure in the context of a well designed prospective randomised trial comparing cemented and uncemented femoral components.

Hip fracture in the elderly is associated with significant morbidity and mortality. Significant intra-operative blood loss and the subsequent need for transfusion significantly contribute to patient morbidity. Making a surgical incision with diathermy reduces wound related blood loss, by coagulating small vessels as tissue is incised, however no study to date has looked at the use of diathermy in making surgical incisions around the hip. In addition, the increasing prevalence of blood borne infections makes the exclusion of sharps from the operative field an attractive option. The aim of this study was to compare diathermy incision with traditional wound opening using a scalpel to incise all layers. 50 patient undergoing hemiarthroplasty for fractured neck of femur were recruited prospectively. Patients on warfarin were excluded from the study while those on aspirin were not. After informed consent was obtained patients were randomized to scalpel or diathermy incision by coin toss.

In the diathermy group the dermis was incised with the scalpel and all further layers with the diathermy, while in both groups diathermy as used for haemostasis. All patients received prophylactic antibiotics at induction and for 24 hours post-op. Wounds were closed in a standard fashion using absorbable sutures for closing fascia and fat layers and surgical staples for skin. Intra-operative parameters measured included: 1) Time to open wound – defined as time taken to open wound from skin incision to complete opening of the fascia lata and achieve haemostasis. 2) Wound length and depth. 3) Wound related blood loss – swabs used while creating and closing the wound were weighed separately. 4) Total operative blood loss. Post-operatively all wound related complications were recorded. Statistical analysis was performed using the un-paired Student t-test parametric data.

Both groups were similar in relation to age, sex and pre-operative aspirin use. Intra-operatively neither wound sizes nor time taken to create the wound were statistically significantly different. In the scalpel group wound related blood loss represented over 30% of the total operative blood loss as compared with only 18.5% in the diathermy group. Post-operatively there were no wound infections or dehiscences in either group, however 4 patients in the scalpel group developed significant wound ooze that responded to conservative treatment. There were no significant wound problems in the diathermy incision group.

This prospective study has shown that the use of diathermy incision for hip hemiarthroplasty significantly reduces wound related blood loss and the incidence of post-operative wound ooze. We conclude that the routine use of diathermy to make incisions around the hip is effective in reducing wound related bleeding without adverse effects on wound healing or infection rate.

The authors wished to determine if macrophage activation and the release of osteolytic cytokines in response to orthopaedic wear debris could be suppressed pharmacologically with the use of anti-inflammatory and anti-oxidant agents.

The current long-term results of total joint arthroplasty are limited by mechanical wear of the implants with an associated immune mediated bone lysis with subsequent loosening and eventual failure. It has been demonstrated that the osteolysis seen in cases of aseptic loosening is mediated by the immune system both directly and indirectly by activated macrophages. Macrophages indirectly cause osteolysis through release of the osteoclast activating cytokines TNFα, IL-1 and PGE2. They also directly resorb bone in small amounts when activated by wear particles.

We utilised established cell culture models of both peripherally derived monocyte/macrophages and lymphocyte enriched co-cultures and examined the effects of polymethylmethacrylate particles alone on the cells in culture. The effect of anti-inflammatory and anti-oxidant agents (dexamethasone, diclofenac and n-acetyl cysteine) in varying concentrations was then examined using ELISA of cytokine release and electron microscopy to examine ultra structural responses.

Cell viability was also measured in cultures over 24 hour periods (at 6, 12 and 24 hours) using Trypan blue exclusion and Coulter counter, while cell type and morphology were determined cytologically, including-naphthyl acetate esterase cytochemical identification and electron microscopy.

The use of N-acetyl cysteine was associated with very significant suppression of TNF, IL-1 and PGE2 in both macrophage and lymphocyte enriched co-culture with no effect on cell viability. While diclofenac was also associated with significant decreases in cytokine expression, it was associated with a decrease in cell viability that approached significance. Dexamethasone did not have a reliable effect on these cytokines. Ultra-structural electron microscopic examination of the cells also demonstrated signs of definite down-regulation of cytoplasmic and nuclear activation.

Novel anti-oxidant therapies and possibly other immune modulating drugs can eliminate the activation of macrophages in response to periprosthetic wear particles without any associated decrease in cell viability and thus may provide a means of reducing the incidence of loosening and failure of total joint arthroplasty.

We evaluated 100 patients in two separate groups of 50 patients for Limb Length Discrepancy after Charnley Total Hip Arthroplasty. The study was a retrospective analysis of the group considered. Group 1 included 50 consecutive patients with unilateral disease who underwent total hip arthroplasty between June 98 – June 99 without intraoperative measurement. Group II included 50 patients with unilateral disease who underwent total hip arthroplasty between June 98 – July 99 with pre-operative templating and intraoperative measurements.

Evaluation was undertaken with radiographs using the method of Williamson and Reckling. Two independent observers evaluated pre-operative radiographs and postoperative radiographs taken at a mean of 3 months (6 weeks – 6 months). The inter-oberserver variation was found in 9 preoperative radiographs and 15 postoperative radiographs in the 100 patients (p< 0.6). The mean age of the patients in Group I was 71 years and 4 months (52–83 years) with 24 males and 26 females. The mean age of patients in group II was 69 years and 7 months (41–82 years) with 25 males and 25 females. 23 patients (46%) in group I had a discrepancy of which 19 patients (38%) had a mean increase of o.4cm (0.1–0.8cm) and 4 patients (8%) had a mean decrease in length of 0.325cm (0.2–1.1cm). In group II 14 patients (28%) had a discrepancy with 9 patients (18%) had an mean increase of 0.41cm(0.1–1cm) and a mean decrease of 0.3cm(0.1–0.6cm).

The discrepancy found in our series of 100 patients in minimal. The discrepancy can be minimised to a further extend with pre operative templating and intraoperative measurements (p< 0.04). Our study supports the adoption of this to prevent limb length discrepancy after total hip arthroplasty.

Introduction: Cement removal in revision total hip arthroplast;y can be technically challenging. Traditional methods can be associated with femoral fracture or uncontrolled cortical perforation and bone loss. A new technique has been developed tha.t permits segmental extraction of bone cement from the femoral canal. Fresh cement is introduced into the old cement mantle and a threaded rod is placed into the wet cement and held in place while the cement hardens. The thread-forming rod is then removed leaving a threaded channel in the cement. Extraction rods are then screwed 1.5 to 2.5 cm into the threaded channel. A slap hammer, which attaches to the opposite end of the extraction rod, is used to remove 1.5- to 2.5-cm segments of cement. The old cement – cancellous bone interface fails before the new-old cement interface and the old/new cement is removed in segments. This allows minimal removal of cancellous bone.

Patients and Methods: Patients who had contra-indications to segmental cement removal such a discontinuous cement mantle were excluded. Twenty-five consecutive cases of revision arthroplasty were entered into the study. The indications were for aseptic loosening in twenty-three cases and deep infection in two cases.

Results: In twenty-two cases the cement was removed completely. In five cases the cement was removed en-bloc in one single extraction rather then in segments. In two cases there was failure of the new cement to bond to the original cement and alternative methods were used. In a further case the cement was removed using a combination of segmental and conventional techniques. There were no cases of cortical perforations or perforaltions in this series. We have found it to be a reliable and safe method of cement removal. The cost of the system is offset by reduced operative time and blood loss.

The current long term results of total joint arthroplasty are limited by mechanical wear of the implants with an associated immune mediated bone lysis with subsequent loosening and eventual failure. It has been demonstrated that the osteolysis seen in cases of aseptic loosening is mediated by the immune system, particularly, both directly and indirectly, by activated macrophages. Macrophages indirectly cause osteolysis through release of the osteoclast activating cytokines: TNFα, IL-1 and PGE2 and also directly resorb bone in small amounts when activated by wear particles.

We wished to determine if macrophage activation and the release of osteolytic cytokines in response to orthopaedic wear debris could be suppressed pharmacologically, with the use of anti-inflammatory and anti oxidant agents.

We utilised established cell culture models of both peripherally derived monocyte/macrophages and lymphocyte enriched co-cultures and examined the effects of polymethylmethacrylate particles alone on the cells in culture. The effects of anti-inflammatory and anti-oxidant agents (dexamethasone, diclofenac and n-acetyl cysteine) in varying concentrations were then examined using ELISA of cytokine release and electron microscopy to examine ultra structural responses.

Cell viability was also measured in cultures over 24 hour periods (at 6, 12 and 24 hours) using Trypan blue exclusion and Coulter counter, while cell type and morphology were determined cytologically, including α-naphthyl acetate esterase cytochemical identification and electron microscopy. The use of N-acetyl cysteine was associated with very significant suppression of TNFα, IL-1β and PGE2 in both macrophage and lymphocyte enriched co-culture with no effect on cell viability. While diclofenac was also associated with significant decreases in cytokine expression it was associated with a decrease in cell viability that approached significance. Dexamethasone did not have a reliable effect on these cytokines. Ultra-structural electron microscopic examination of the cells also demonstrated signs of definite down-regulation of cytoplasmic and nuclear activation.

We have demonstrated, therefore, that novel anti-oxidant therapies and possibly other immune modulating drugs can eliminate the activation of macrophages in response to peri-prosthetic wear particles without any associated decrease in cell viability and thus may provide a means of reducing the incidence of loosening and failure of total joint arthroplasty.