Abstract

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.

Background

Comminuted fractures involving the tibia are associated with a high level of complications including delayed healing and non-union, in conjunction with dramatically increased healthcare costs. Certain clinicians utilise a Pixel Value Ratio (PRV) of 1 to indicate such fracture healing. The subjectivity of this method has led to mixed outcomes including regenerate fracture. The poor prognosis of complex load bearing fractures is accentuated by the fact that no quantitative gold standard currently exists to which clinicians can reference regarding the definition of a healed fracture. The aim of the current study is to use patient specific finite element analysis of complex tibial fractures treated with Ilizarov frames to demonstrate callus maturation and to determine the optimum frame removal time.

Background

There have been limited published reports on the clinical results of cervical artificial disc replacement. Goffin et al reported a 90% rate of good to excellent results at 1 to 2 yrs after Bryan disc replacement. Wigfield et al reported a 46% improvement in pain and 31% improvement in disability 2 yrs after Prestige cervical disc replacement.

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: Bone Morphogenic Proteins (BMP’s) are a family of bone-matrix polypeptides isolated from a variety of mammalian species. Implantation of osteogenic proteins induces a sequence of cellular events that leads to the formation of new bone.

Recombinant human osteogenic protein-1 (rhOP1 or BMP-7) has now been produced and is commercially available.

Rationale: OP.1 has been used in our centre since early 2003 and we now report on our experience with its use in the treatment of fracture non unions in a general orthopaedic trauma setting.

Methodology/Results: OP1 has been used in 19 fracture non unions, the commonest site being the tibia but also in the humerus and forearm. Five of these cases had previous autologous bone grafting. There was one case of deep MRSA infection in a proximal humerus fracture. There were no complications associated with the use of OP1 and specifically there were no instances of symptomatic heterotopic bone formation. Eighteen fractures went on to clinical and radiological union.

Conclusions: Autogenous bone is the current standard in the management of fracture non union because of its high osteogenic potential and biocompatibility. Donor site morbidity and quantity remain drawbacks. The use of OP.1 in the treatment of tibial non unions is well documented in the literature but there is little written about its use in other sites.

We are encouraged by our early experiences with the use of OP1 in numerous anatomical sites and apart from issues of cost would see great potential for further use.

Aim: To study the effect of traction on the compartment pressures during intramedullary nailing of closed tibial shaft fractures. Methods:Thirty consecutive patients with Tscherne C1 fractures were randomised into two groups. Sixteen patients underwent intramedullary nailing of the tibia with traction and fourteen patients without traction. Compartment pressures were measured before the application of traction or commencement of the procedure and at the end of the procedure with a Stryker¨intracompartmental pressure monitor system. Results:The data collected was analysed using paired student t-test. There was no statistically signiþcant difference (p> 0.05) in the preoperative mean compartment pressures for both groups. The mean postoperative measurements were higher in all the four compartments in the traction group (p< 0.05). None of the pressures reached the critical level Conclusions:These results show that traction increases compartment pressures signiþcantly. The group considered did not have compartment syndrome possibly due to lower pressures. With greater pre operative compartment pressures, it can reach a critical level on traction necessitating decompression. We advocate the procedure be done without traction.

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 aim of this study was to evaluate the effect of traction on the compartment pressures during intramedullary nailing of closed tibial shaft fractures.

The study design was a randomised prospective trial. The period of the study was Sept ’99 to Dec 2000. 30 consecutive patients with Tscherne C1 fractures were randomised into two groups.16 patients underwent intramedullary nailing of the tibia with traction and 14 patients without traction. Compartment pressures were measured before the application of traction or commencement of the procedure and at the end of the procedure. The method described by Gulli and Templeman was used to measure all the four compartments of the injured limb. The pressures were measured with a Stryker® pressure monitor. The absolute and differential compartment pressures were recorded. All patients were followed up for the duration of at least 8 months and until fracture union.

The data collected was analysed using paired student t-test. There was no statistically significant difference (p> 0.05) in the preoperative mean compartment pressures for both groups when all the four compartments were measured individually. The mean postoperative measurements were higher (range 9–10 mmHg) in all four compartments in the traction group. This was statistically significant (p< 0.05). None of the pressures reached the critical level as they were more than 30 mmHg below the diastolic pressure (differential pressure).

These results show that traction increases compartment pressures during intramedullary nailing of tibial shaft fractures. The group considered did not have compartment syndrome possibly due to less soft tissue injury. With greater soft tissue injury and greater preoperative compartment pressures, compartment pressures can reach a critical level necessitating decompression.

We conclude that intramedullary nailing without traction reduces the chances of significant increase in compartment pressures and advocate the procedure be done without traction.

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.

The effects of infection following implantation of an orthopaedic prosthesis are devastating. The prevention of perioperative contamination is therfore of the utmost importance in arthroplasty. We undertook a prospective study to assess bacterial contamination in elective arthroplasty surgery. Splash bowls containing sterile saline are used to store and clean instruments used during the course of a procedure. The incidence of bacterial proliferation in splash bowls was examined as a marker of intra-operative contamination. A 100mL aliquot of fluid was removed from the splash basin at the end of the procedure and passed through a grid membrane using a vacuum pump. The membrane filter was then plated on chocolate agar and colony counts recorded at 24 and 48 hours. Organisms were identified by standard techniques. Demographic data, and perioperative data including the duration and type of procedure, the number of scrubbed and other personnel in theatre and the type of skin preparation and gowns used were also noted. A total of 43 cases were examined. 14 samples yielded positive cultures. Staphylcoccus was the most commonly cultured organism (9 cases). Four patients grew Pseudomonas species. Five patients grew other Gram-negative organisms including Neisseria and bacillus subspecies. Five patients grew multiple organisms. Mean duration of follow up was 8.4 months (range 6 – 18 months). None of the patients with contaminated samples developed any clinical signs of infection in the perioperative period; nor was there clinical or radiological evidence of infection or loosening on subsequent follow up. Despite the use of a laminar airflow system in all cases, in excess of 30% of cases were contaminated. This study underlines the importance of adhering to rigorous protocol in theatre including minimising theatre traffic and the use of antibiotic prophylaxis.