Biomechanical alignment of the knee is a major determinant in the outcome of Total Knee Arthroplasty. However, the best method to assess the alignment is yet undecided. Conventional methods use hip to ankle “long” standing x-rays but these suffer from technical difficulties and hence are a potential for error. Short x-rays are considered to have doubtful accuracy.

This study aimed to assess if the “short” AP x-rays could be used to assess the lower limb axis within a range of statistically insignificant and clinically acceptable difference.

The results indicate the readings from the short x-rays were not statistically different from those obtained from the long x-rays in four sets of observations. The largest difference between any two readings was 0.68 degrees. The analysis of data showed that the measurements from the short x-rays could indeed be used to assess the long axis of the lower limb with the provison that there is no gross femoral shaft deformity.

Introduction: The aims of this study are:

To report and validate the early migration rates of the collarless polished tapered hip replacement using manual and computer measurements

To report early clinical results of the CPT hip

Patients and methods: 80 patients undergoing primary total hip replacement in a single centre were prospectively recruited into the trial. There were 59 females and 21 males: age range 31–84 years, (mean 68 years sd 9.86). Surgery was performed through an anterolateral approach in all cases. A standard cementing technique using a cement gun and cement restrictor was employed. The patients had standardised anteroposterior standing hip radiographs taken post operatively, then yearly. The migration was measured along the long axis of the femoral component In the anteroposterior plane, using the tip of the greater trochanter as a bony landmark. Measurements were made by two independent observers (specialist registrars). Plain radiographs were measured manually using a ruler and set square and digitised images using a software package designed in-house at Dundee University. Correction for magnification was incorporated. Hip assessments were performed at each review by an independent reviewer.

Results: The mean migration rates and 95% confidence intervals (Cl) and mean Harris pain and Harris hip scores and Std Deviations were:

There was no significant difference between inter or intra observer measurements for hip migration.

This is the first study to date that we are aware of that describes the subsidence rates of the CPT hip which includes validation by inter and intra observer readings.

Radiographs are often used to determine the varus/ valgus alignment of the prosthesis in relation to the long axis of femur. This is usually considered to be one of the important parameters in predicting early mechanical failure of the total hip replacement.

The measurements made by the University of Dundee X-Ray Analysis Software and skilled manual operators of the varus and valgus angulations of hip prosthesis in relation to the femoral shaft were compared for inter and intra-observer reliability.

The manual measurements were carried out on the same randomly selected digitised images of 78 postoperative X-rays by two independent observers and by the same analysis software twice.

The results of the study showed a very high agreement between the readings of the two methods (the largest difference was 0.6 degrees) and two observers (the largest difference being 0.08 degrees) indicating excellent intra and inter observer reliability. The lowest correlation was 0.82 and this was between software reading 1 of observer 1 and software reading 1 of observer 2. The highest correlation of 0.99 was between software reading 1 and software reading 2 for the same observer. The software analysed the x-rays with precision and accuracy and was much faster than manual measurement. A further benefit of the computerised method is an unskilled operator can be trained in 15 minutes to use the software

Introduction: The aims of this paper are to compare the results of Measuring migration rates on radiographs manually and by computer assisted analysis of digitised images.

Methods: Standardised anteroposterior standing hip radiographs taken post operatively and then yearly following hip replacement were used. The radiographs were then scanned at 150 dpi (gray scale) and saved as tif files. The migration was measured manually by drawing a line along the long axis of the femoral component connecting the distal tip, to the notch, which is used to impact the stem proximally. This gives us the length of the hip replacement and an axis along which migration can be measured. The tip of the greater trochanter was selected as a bony landmark. On the plain radiographs two sets of readings were made by one observer. The digitized images were then analysed in the same way using a software package (designed in-house at the University of Dundee). Two sets of readings were performed by observer one and a second set by an independent observer. Statistics: Inter and Intra observer rates were calculated using a paired sample t test.

Results: For the manual readings intra observer mean difference was 0.53mm (Cl 0.31–0.74mm). Comparing manual vs computer readings for observer one there was a correlation of 0.89. For the computer readings intra observer mean difference was 0.36mm (CI 0.64–0.8mm) and inter observer mean difference 0.16 mm, both non-significant differences. This evidence shows that the readings made manually and by computer were not significantly different and that there was no significant inter and intra observer variation. The advantage of computer storage and reading being the faster analysis, the ability to store and access large numbers of radiographs. The disadvantages being the need to scan the radiographs to allow measurement.

Osteoporosis has been implicated as one of the causative factors for Colles’ fracture. The current study was designed to establish whether the degree of osteoporosis has any influence on the radiological severity of Colles’ fracture in active elderly peri-menopausal female patients.

Female peri-menopausal patients who sustained a Colles’ fracture were studied. The ultra distal Bone Mineral Density (uBMD) was determined using DXA in the contralateral non-fractured wrists, which were also x-rayed. Anthropometric measurements were recorded, the radiological severity of the fracture was assessed using a computerised image analysis system, which measured the radial angle, height and width on AP view and the dorsal tilt on lateral view. Measurements were carried out on the fractured and the normal wrist. Pearson’s correlations between age, height, weight, BMI, uBMD and fracture measurements were carried out. The Bone Deformity Index (BDI) was defined as the summation of all the differences of the previous parameters between the normal and fractured wrists on the AP view. ANOVA, with bonferroni correction, was used to compare the parameters and the radiological measurements between normal, osteopenic and osteoporotic patients.

Sixty-seven patients were recruited. Those with Barton fractures, previous fractures of the wrist or a previous history of chronic treatment with bone modifying drugs were excluded. Forty eight patients were analysed. The parameters measured had a tendency to be worse with increasing degree of osteoporosis, although the only significance was in the measurement of dorsal tilt on the lateral view (p = 0.05). The normal patients were significantly heavier (89.3 kg) than the other two groups (p =0.03). In the osteoporotic group the correlation between uBMD and the BDI was −0.6, between uBMD and radial height difference was –0.5 and between uBMD and the angle difference in AP was also –0.5. Similar correlations in normal patients were not statistically significant. Power estimates were performed. Because of the relatively large variability within the samples, a sample size of 550 cases will be necessary to reach a power of 80% to detect a pre-defined clinically significant difference of 3 units in the BDI between groups.

The evidence from this study suggests that the initial radiological deformity in osteoporotic patients was greater in those patients with severe degree of osteoporosis. The deformity in normal patients did not have a correlation with the uBMD but these patients were significantly heavier, indicating a different combination of causative factors in these two groups. The precision of the current method of x-ray measurements has enabled a precise definition of the variability within the different groups, resulting in the production of information that was not previously available.