Introduction

Total hip replacement (THR) is a very common procedure performed for the treatment of osteoarthritis of the hip. The aim of THR is to restore function and quality of life of the patients, by restoring femoral offset, leg length, centre of rotation, and achieving stability, to avoid dislocation postoperatively.

Introduction

There are conflicting views when assessing the best imaging modality by which to assess long leg alignment pre and post operatively for patients’ receiving primary total hip replacements. It has been a long standing standard that long-leg radiographs are used for measuring and interpreting alignment of the lower limb, but recently it has been suggested that CT imaging may be a better option for this assessment.

Alignment and soft tissue balance are two of the most important factors that influence early and long term outcome of total knee arthroplasty.

Current clinical practice involves the use of plain radiographs for preoperative planning and conventional instrumentation for intra operative alignment.

The aim of this study is to assess the Signature^TM Personalised system using patient specific guides developed from MRI. The Signature^TM system is used with the Vanguard^RComplete Knee System. This system is compared with conventional instrumentation and computer assisted navigation with the Vanguard system.

Patients were randomised into 3 groups of 50 to either Conventional Instumented Knee, Computer Navigation Assisted Knee Arthroplasty or Signature Personalised Knee Arthoplasty. All patients had the Vanguard Total knee Arthroplasty Implanted.

All patients underwent Long leg X-rays and CT Scans to measure Alignment at pre-op and 6 months post-op. All patients had clinical review and the Knee Society Score (KSS) at 1 year post surgery was used to measure the outcome.

A complete dataset was obtained for 124 patients. There were significant differences in alignment on Long leg films ot of CT scan with perth protocol. Notably the Signature group had the smallest spread of outliers.

In conclusion the Signature knee system compares well in comparison with traditional instrumentation and CAS Total Knee Arthroplasty.

Inter- and intra-observer variation has been noted in the analysis of radiographic examinations with regard to experience of surgeons, and the monitors used for conducting the evaluations. The aim of this study is to evaluate inter/intra observer variation in the measurement of mechanical alignment from long-leg radiographs.

40 patients from the elective waiting list for TKA underwent long leg radiographs pre-operatively and 6 months post-operatively (total of 80 radiographs). The x-rays were analysed by 5 observers ranging in experience from medical student to head orthopaedic surgeon. Two observers re-analysed their results 6 months later to determine intraobserver correlation, and one observer re-measured the alignment on a different monitor. These measurements were all conducted blindly and none of the observers had access to the others’ results.

80 radiographs were analysed in total, 40 pre-op and 40 post-op. The mechanical alignment was analysed using Pearson's correlation (r = 0 no agreement, r = 1 perfect agreement) and revealed that experience as an orthopaedic surgeon has little effect on the measurement of mechanical alignment from long leg radiograph. The results for the different monitor analysis were also analysed using Pearson's correlation of long leg alignment. Monitor quality does seem to affect the correlation between alignment measurements when reviewing both intra and inter observer correlation on different computer monitors.

Surgical experience has little impact on the measurement of alignment on long leg radiographs. Of greater concern is that monitors of different resolution can affect measurement of mechanical alignment. As there might be a range of monitors in use in different institutions, and also in outpatient clinics to surgical theatres, close attention should be paid to the implications of these results.

Introduction & aims

Different racial groups show variations in femoral morphometry. Femoral anteroposterior measurement and mediolateral measurement are key variables in designing femoral implant for TKR. Their aspect ratio determines the shape and mediolateral sizing for the proper patellofemoral tracking and uniform stress distribution over the resected distal femoral surface.

Stable, anatomical fixation of acetabular fractures gives the best chance of a good outcome. We performed a biomechanical study to compare fracture stability and construct stiffness of three methods of fixation of posterior wall acetabular fractures.

Two-dimensional motion analysis was used to measure fracture fragment displacement and the construct stiffness for each fixation method was calculated from the force / displacement data.

Following 2 cyclic loading protocols of 6000 cycles, to a maximum 1.5kN, the mean fracture displacement was 0.154mm for the rim plate model, 0.326mm for the buttress plate and 0.254mm for the spring plate model. Mean maximum displacement was significantly less for the rim plate fixation than the buttress plate (p=0.015) and spring plate fixation (p=0.02).

The rim plate was the stiffest construct 10962N/mm (SD 3351.8), followed by the spring plate model 5637N/mm (SD 832.6) and the buttress plate model 4882N/mm (SD 387.3).

Where possible a rim plate with inter-fragmentary lag screws should be used for isolated posterior wall fracture fixation as this is the most stable and stiffest construct. However, when this method is not possible, spring plate fixation is a safe and superior alternative to a posterior buttress plate method.

Objective: To present the clinical features, radiological findings and differential diagnosis of this rare benign condition.

Design: Melorheostosis (Leri’s Disease) is a rare mesenchymal dysplasia commonly exhibiting hyperostosis on the internal and external aspect of tubular bones in a sclerodermal distribution. It usually occurs in the limbs, frequently crosses joints and there is often ossification in local soft tissues. Presenting features may include pain, restricted joint movement and skin thickening. It very rarely affects the spine and its cause is unknown.

Subject: A 40-year-old female presented with insidious onset of mild mid thoracic back pain. There was no history of trauma and she had no past medical or family history. She underwent a six-month course of physiotherapy but this failed to help her symptoms. She developed a small lump over the area of pain and her GP arranged an X-Ray. This showed an irregular area of high attenuation over the right side of the tenth thoracic vertebra. A CT demonstrated a “dripping candle wax” appearance of densely calcified cortical bone undulating over the right side of the body and posterior elements of T10. The ossification crossed the synovial zygoapophyseal joint but not the intervertebral disc and a diagnosis of melorheostosis was suggested. MRI supported the CT findings and confirmed the presence of a soft tissue lesion over the dorsal process of T10. A bone scan verified the solitary nature of the lesion and showed widening of the right side of the body of T10 with increased focal uptake. All blood and urine investigations were normal.

Results: The patient underwent an open biopsy to obtain sufficient tissue for histological diagnosis and confirm that the lesion was benign in nature. It was felt that the dense ossification of the lesion would make percutaneous biopsy difficult. The most important differentials to exclude were an osteosclerotic bone metastasis and osteosarcoma. Other differential diagnoses were a parosteal osteoma, a burnt out osteoblastoma and a giant bone island. The soft tissue histology showed a necrotic fibrocartilagenous mass. The bone samples required prolonged decalcification prior to cutting and were composed of compact cortical bone similar to the appearances seen in ivory osteoma and also consistent with melorheostosis. This pathological pattern and the radiological finding of cortical compact bone crossing a synovial joint confirms the diagnosis of melorheostosis.

Conclusions: Spinal melorheostosis is a rare condition. The diagnosis should be considered in the differential of atypical osteosclerotic lesions of vertebrae. Adequate histological sampling is essential in order to exclude malignancy.

We studied 58 women of employable age with the carpal tunnel syndrome in order to determine whether the histological appearances of the carpal tunnel, tenosynovium and flexor retinaculum are influenced by work practices. Age, body mass index and the duration of symptoms did not correlate with the extent of oedema or fibrosis within the tenosynovium. The incidence of abnormality on histological examination of the tenosynovium was the same in employed and unemployed patients (p = 1.0), and was not influenced by the level of repetition (p = 0.89) or force (p = 0.29) of work. Myxoid degeneration within the flexor retinaculum was, however, more common in women undertaking ‘high-force’ work. Apart from this finding, the results suggest that work practices do not affect tenosynovial thickening, fibrosis or oedema in patients with carpal tunnel syndrome.

In a prospective study of the measurement of osteoporosis in patients with fracture of the femoral neck, we compared a histological with a radiological method. We found no significant correlation between histological planimetry and the radiological six metacarpal hand index in patients with either cervical or trochanteric fractures. This demonstrates that metacarpal morphometry cannot predict histological osteoporosis of the iliac crest.

In this study 201 elderly patients with femoral neck fractures were compared with 30 osteomalacic patients with the same injury. Hypocalcaemia and a raised alkaline phosphatase level are common biochemical abnormalities in elderly patients with femoral neck fractures. In only a minority of patients, however, were they associated with histologically proven osteomalacia. By using the combination of hypocalcaemia and a raised alkaline phosphatase it is possible to identify a subgroup (approximately 10% of all admissions) in whom osteomalacia is relatively likely.

In a series of over 1000 elderly patients with femoral neck fracture, who were routinely screened by iliac crest bone biopsy, a 2% prevalence of osteomalacia was found. This low figure suggests that osteomalacia is not a significant predisposing factor in the development of these fractures and that routine screening is not cost-effective.