Introduction: Femoral offset plays an important part in the biomechanics of the hip with inaccurate balancing at the time of arthroplasty leading to abductor weakness, leg length discrepancies and altered wear characteristics.

Aim: To look at the degree of external rotation of the leg at the time of pre-operative x-rays and to assess the effect of this on templating for femoral offset.

Methods: A radiological review of a cohort of patients attending for hip arthroplasty with unilateral osteoarthritis.

Results: Externally rotated posturing of the affected leg is common amongst patients with osteoarthritis attending for hip arthroplasty. The effect of this change in the positioning of the femoral neck is to create an apparent reduction in the offset of the femoral shaft. This will lead to underestimation of the correct offset for the chosen prosthesis. In over 50% of cases templating would have been incorrect.

Conclusions: When templating prior to hip arthroplasty surgery an assessment of the profile of the lesser trochanter will give an impression of the leg position. If this is externally rotated it should be presumed that the offset will be larger than the measured value. If the other hip is in a better rotational position this should be used for assessment.

Aim: A retrospective review of the triple pelvic osteotomies performed between 1988 and 2002 identifying the factors that may predict a favourable outcome from surgery.

Method: A case note and x-ray review identifying various parameters that influence outcome.

Results: 30 osteotomies in 26 patients have been studied. 3male and 27 female patients have been identified. All patients were symptomatic prior to surgery complaining of pain and reduced exercise tolerance. Following surgery 21 patients were satisfied with their outcome and 9 patients had poor results.

The average age of patients with a good outcome was 20.9 years. The average age of patients with a poor outcome was 30.9 years.

There was no correlation between the correction of either the Sharp angle or the centre-edge angle and outcome. Sphericity of the head was unrelated to outcome. Obesity was associated with a poorer outcome in older patients.

Conclusion: Triple pelvic osteotomy provides a reliable method of improving symptoms in younger patients with dysplastic hips. An increased rate of failure should be expected in patients over thirty years of age.

Introduction: Template use prior to hip arthroplasty is a valuable form of pre-operative planning. The femoral neck anteversion may influence the interpretation of the femoral off-set on plain x-rays

Method: The femoral neck anteversion of a series of adult patients with developmental hip dysplasia has been assessed using CT guided measurement. Using this data and more normal ranges of anteversion we have been able to estimate the effect of anteversion on perceived off-set.

Results: Femoral neck anteversion significantly effects the perceived offset at angles of greater than 20 degrees. The average femoral neck anteversion in our series of patients with hip dysplasia was 22 degrees. With a perceived off-set of 40mm on an AP x-ray the actual offset becomes 44mm in a patient when the patient has 25 degrees of anteversion.

Conclusion: Femoral neck anteversion is an important factor when considering the appearance of plain hip x-rays. Recognition of this factor may improve the ability of the operating surgeon to assess the correct components pre-operatively.