Introduction

Dislocated hip hemiarthroplasties (HA) are associated with a 45% revision rate and 40% mortality rate.

Implant selection for HA operations vary with no universally accepted implant choice. The WHiTE3 trial suggested older designs such as the Thompson has equitable outcomes to more modern and expensive implants such as the Exeter V40+Unitrax.

Our multi-centre consecutive series of NOFs patients treated with HA assesses the impact of surgical and patient factors on dislocation risk.

Adverse reaction to metal debris (ARMD) is well recognised as a complication of large head metal on metal total hip replacement (THR) leading to pain, bone and tissue loss and the need for revision surgery. An emerging problem of trunnionosis in metal on polyethylene total hip replacements leading to ARMD has been reported in a few cases. Increased metal ion levels have been reported in THR's with a titanium stem and a cobalt chrome head such as the Accolade-Trident THR (Stryker).

We present 3 cases of ARMD with Accloade-Trident THR's with 36mm cobalt chrome head and a polyethylene liner. Metal ion levels were elevated in all three patients (cobalt 10.3 – 161nmol/l). Intraoperative tissue samples were negative for infection and inflammatory markers were normal. Abnormal fluid collections were seen in all three cases and bone loss was severe in one patient leading to a proximal femoral replacement. Histology demonstrated either a non-specific inflammatory reaction in a case which presented early or a granulomatous reaction in a more advanced case suggesting a local foreign body reaction. All patients had improved symptoms post-operatively. 1 patient who had staged bilateral Accolade-Trident THR's required revision of both THR's.

ARMD in metal on polyethylene THR's with a titanium stem represents a potential emerging problem. Further studies are required to assess whether these occurrences are rare or represent the tip of an iceberg.

Introduction

Prosthetic joint infections (PJIs) generate significant clinical and socio-economic pressures on the health service. Recent advances in the diagnosis of PJIs, with biomarkers and sonification have aided delineation of PJIs from aseptic processes. However these investigations are not widely available and expensive. Interface membrane histology has been shown to be superior to pseudocapsule histology; we therefore sought to ascertain the diagnostic benefit of deep canal sample microbiology in conjunction with standard pseudocapsule sampling.

We report our retrospective multicentre experience of managing periprosthetic knee fractures using locking plates, cemented nails and distal femoral prosthesis. The Aim of this study is to analyze the practicality of management of these injuries using modern methods of fixation or salvation. 62 patients presented to 3 centres between 2003 and 2010. After implementation of inclusion criteria, clinical, radiological and functional outcomes were evaluated in 54 patients, with a minimum follow-up of 6 months. 34 patients were treated with locking plates (10 males, 24 female; mean age 76), 16 with cemented/locking nails (4 males, 12 females; mean age 84.5), and 4 with distal femoral replacement prosthesis (2 males, 2 females; mean age 79).

Locking plates which were used with a minimally invasive pattern produced the best outcomes in our study. A statistical significance of p value of less than 0.01 was found in union time between patients operated on with an open technique (6.69±2.69 months) and those operated on with a minimally invasive technique (3.6±0.91 months). Nailing with augmented cement is a useful technique in patients who are not suitable for challenging surgery & rehabilitation programmes. There was a significant difference in mean time to functional weight bearing (p< 0.01) between the plate group (4.79±2.6 months) and the nail group (2.63±0.5 months). Post-operative range of motion was also better for nails (106.36±14.33^O flexion) compared to plates (93.24±26.8^O), a result that approached significance (p=0.065). We recommend minimal invasive plating in uncompromised physiological conditions, as an ideal method of fracture fixation in view of statistically significant union rates. Cemented nailing is recommended in patients where early rehabilitation is essential. Distal Femoral prosthesis replacement is a useful salvage method.

Background: The use of sacro-iliac screws to restore the stability of posterior pelvic ring dissociations has become a standard technique. Several methods are described including fluoroscopy, CT and computer assisted techniques. Fluoroscopically assisted insertion is the standard technique. Multiple exposures of ionising radiation permit acquisition of a target in sequential planes, requiring a process of interpolation for 3-D localisation. A computer assisted technique facilitates the simultaneous visualisation of multiple planes following a single image intensifier acquisition and registration process in each plane. The purpose of this study is to demonstrate the accuracy of a computer assisted surgery technique and quantify the predicted reduction in radiation exposure.

Methods: 10 embalmed human cadavers were used. In each specimen, a sacro-iliac screw was simulated by passing a 5mm reamer over a 3.2mm guide wire. The index track was formed with a closely sheathed 4.8mm drill and was inserted with the standard fluoroscopically assisted technique in the left hemipelvis and a computer assisted technique(Vector Vision trauma) on the right. Registration of the system is achieved by the placement of infra red reflective arrays on all tracked objects. These include the right and left hemi-pelvis, the fluoroscope, the drill guide and the driver unit. The system is an open platform which registers arrays of known geometry whilst permitting the registration of instruments by means of an instrument calibration matrix. The pelvic T and Y pattern fiducials are fixed rigidly to inter-table threaded pins at the level of the gluteal tuberosities. The standard acquisition projections are inlet and outlet views for both techniques with the addition of lateral projections although the latter were not directly used for navigation. Postoperative CT scans demonstrate the actual tracks and analysis is facilitated by means of a digital mapping technique.

Results: The accuracy of the fluoroscopically assisted and computer assisted techniques is identical. The procedure time was significantly longer for the computer assisted technique although most of the additional time was accounted for by the “line of sight” registration process. There was a reduction in both the total screening time and the measured radiation dose in the case of the computer assisted technique although this did not reach statistical significance as the sample size is relatively small.

Conclusions: The navigation of sacro-iliac screw tracks by means of both fluoroscopically assisted and computer assisted techniques proves equally accurate in a human cadaveric model.

Aim: A comparative in vitro study to identify which knot conþguration is the strongest and most secure in orthopaedic surgery. Background: It has been proven that monoþlament sutures are less damaging to soft tissues than multiþlament (braided) ones. However braided sutures are still popular with orthopaedic surgeons. It is thought that this is due to the knot-holding properties of braided materials. Methods: Four commonly used surgical knots were tied on a novel knot-testing rig by the same operator. They were subjected to a series of static (n=300) and pulsatile (n=380) forces in different environments, to simulate anticipated physiological demands. These tests were performed on both absorbable and non-absorbable sutures in both mono-þlament and braided form. Results: These 680 knotting tests show that the surgeonsñ knot is not always the best option in every situation and that surgeons should have a range of knots in their arsenal. Conclusions: This study has shown that monoþlament sutures can be as strong and reliable as braided materials if tied with appropriate knots. Therefore, by using a variety of knotting techniques, a surgeon may rely more heavily on monoþlament sutures, thereby reducing the soft-tissue trauma and infection risk that braided sutures involve.

To determine whether elderly patients presenting with a fracture of the proximal femur have an underlying vitamin D deficiency.

We identified 59 consecutive cases of a fracture of the proximal femur over a 10-week period. 16 patients were excluded as they had a secondary underlying cause of bone loss which included chronic renal disease, rheumatoid arthritis, thyroid/parathyroid disorders, long term steroid usage and malignancy.

Of the 43 that were eligible for the study, 7 were men and the average age was 81 years. 9 had sustained previous osteoporotic fractures. The majority mobilised independently or with 1 stick prior to the fall and the mechanism in all cases was a low velocity injury from standing height or less.

The mean vitamin D3 level in these cases was 28. 3 nmol/ l. 28 of the 43 had a pathologically low level of vitamin D3 as defined as < 30nmol/l.

The mean PTH level was 53. 7 nmol/ l. 15 of the 43 had an elevated PTH and all 15 were also deficient in vitamin D.

The mean Albumin, an indicator of nutritional status, was 29 g/l.

This study highlights that 65% of the patients who present with a fracture of the proximal femur are depleted in vitamin D. The ageing process is associated with a reduction in the intake of vitamin D, gut absorption and its sunlight activation. Repletion of vitamin D and suppression of parathyroid hormone, both prophylactically or at the time of injury, may reduce future fracture risk and assist in fracture repair.