The standard approach for kinematic analysis of knee joints has been roentgen stereophotogrammetry (RSA). This approach requires implanting tantalum beads during surgery so pre- and post-surgery comparisons have not been conducted. CT- fluoroscopy registration is a non-invasive alternative but has had accuracy and speed limitations. Our new algorithm addresses these limitations.

Our approach to the problem of registering CT data to single-plane fluoroscopy was to generate a digitally reconstructed radiograph (DRR) from the CT data and then filter this to produce an edge-enhanced image, which was then registered with an edge-enhanced version of the fluoroscopy frame. The algorithm includes a new multi-modal similarity measure and a novel technique for the calculation of the required gradients.

Three lower limb specimens were implanted with 1 mm tantalum beads to act as fiducial markers. Fluoroscopy data was captured for a knee flexion and femur and tibia CT data was registered to the fluoroscopy images.

A previous version of our algorithm (developed in 2008) showed good accuracy for in-plane translations and rotations of the knee bones. However, this algorithm did not have the ability to accurately determine out-of-plane translations. This lack of accuracy for out-of-plane translations has also been the major limitation of other single-plane 2D-3D registration algorithms. Fregly et. al. and Dennis et. al. reported standard deviations for this measurement of 5.6 and 3.03 mm respectively. The latest version of our algorithm achieves error standard deviations for out-of-plane translations of 0.65 mm. The algorithm includes a new similarity measure, which calculates the sum of the conditional variances (SCV) of the joint probability distributions of the images to be registered. This new similarity measure determines the true 3D position of the bones for a wider range of initial disparities and is also faster than the cross-cumulative residual entropy (CCRE) measure used in the 2008 version. For a set of initial 3D positions ranging from ± 5 pixels and ± 5 degrees the proposed approach successfully determined the correct 3D position for 96% of cases–whilst the approach using CCRE was successful for only 49% of cases. The algorithm also required 60% less iterations than the previous CCRE approach.

The new registration algorithm developed for the project provides a level of accuracy that is superior to other similar techniques. This new level of accuracy opens the way for a non-invasive mechanism for sophisticated kinematic analysis of knee joints. This will enable prospective, longitudinal and controlled studies of reconstruction surgery.

Locking of the MCP joint of the finger, except with stenosing tenosynovitis, is relatively rare. The middle finger is most frequently involved. We treated 7 patients who had locking of the MCP joint of the middle finger because of osteophyte of the metacarpal head. The locking of the MCP joint usually occurred in the older patient as a result of significant osteophyte around the metacarpal head. Unlocking of the MCP joint was done by closed manipulation under local anaesthesia.

Locking of the MCP joint of the finger because of other causes than tenosynovitis has been reported infrequently.

Locking of the MCP joint caused by osteophyte of the head of the metacarpal is characterised by painful loss of extension of the MCP joint without loss of flexion.

We have treated 7 patients who had locking of the MCP joint occurring in the middle finger with an obvious osteophyte of the metacarpal head. Seven patients, 4 women and 3 men, were treated in our Department. None of the patients had a history of trauma to their hands, and in all of them it was the dominant hand which was affected and usually due to powerful full flexion movement of the fingers. The average age was 73.8 years (65 – 81). The duration of locking was from 3 hours to 14 days. All the patients were treated within 30–60 minutes after reporting to our Clinic. The presentation of the patients was extremely similar. In all cases active and passive extension was blocked and they had pain around the finger. Full flexion was possible. The MCP joint was tender around the palmar aspect with slight diffuse swelling around the dorsal aspect.

Radiographs of the MCP showed degenerative changes in all the patients and oblique views demonstrated an osteophyte either on the ulnar or the radial side of the head

Local anaesthetic Lignocaine 1% 5ml was injected in the MCP and around the joint and after 5–10 minutes manipulation was performed, unlocking achieved and the patients straightaway extended and flexed the finger fully. No-one underwent surgical release. Follow-up from 3 to 8 months, average 6 months. No recurrence of the locking.

Akio Minami reported 4 cases of MCP joint locking of the middle finger, treated surgically. Williams classified the locking of the MCP joint in 3 groups. Langenskiold reported 2 cases of intrinsic locking of the MCP due to catching of the collateral ligament on the lateral bony projection of the metacarpal head.

It is very difficult to explain why the middle finger is most likely affected. Kessler noted that the MCP joint seldom participates in a generalised degenerative OA.

Introduction: Understanding the factors in progression of curves in spinal deformities are crucial to the planning of treatment. While clinical and genetic parameters appear to be involved in the progression of adolescent idiopathic scoliosis, it remains very difficult to objectively study this as it is difficult to find pedigree cohorts. We wish to report the difference in progression of adolescent idiopathic scoliosis curves in two essentially homogenous racial groups that utilise our Scoliosis service.

Methods and Results: Three hundred and twenty-four patients were treated at the Scoliosis service of our Institute from 1985 to 1998. The aetiology of the curves were as follows: 218 AIS, 37 Neuromuscular, 48 Congenital, 21 other diagnostic type, and 11 aetiology not known. The racial distribution of utilisation of service: 44% Malay, 44.7% Chinese, 2.0% Indian and 9.3% not known or mixed race. The Malay and Chines groups were matched and studied. There was no difference in the menarchal age, curve size at presentation and age at presentation to the service (P=0.3). Patients were analysed in two groups: below 10 years, and above 10 years at presentation.

The rate of progress of the AIS curves > 50° were fastest in the Chinese patients with a rate of 14.7°/year; with Malay patients progressing at 8.4°/year. Rates of progression of curves 30–50° were the same for both groups with Chinese at 7.7°/year, and Malays at 6.7°/year. Curves < 30° progressed at the same rate also with Chinese at 5.0°/year and Malays at 7.0°/year.

Conclusion: From our data, it appears that race (genetics) does influence the rate of progression of AIS curves.