Analysis techniques for congruence of the patellofemoral joint.

Quantifying joint congruence may help to understand the relationship between joint function and health. In previous studies, a congruence index (CI) has been used to define subject-specific joint congruence. However, the sensitivity of the CI algorithm to surface representation was unknown. The purpose of this study was to assess the effects of applying five modifications (M1-M5) to the CI algorithm to determine whether the magnitude and variability of the patellofemoral CI is dependent on the surface representation used. The five modifications focused on calculating the CI based on the principal curvature (M1) at the centroid of the contact region, (M2) using an root mean square value for the contact region, (M3) using a mean value for the contact region, (M4) using all digitized points of the patellar surface, and (M5) using all digitized points in contact. The CI found using the contact area (M1, M2, M3, and M5) provides a local measure for congruence, which was shown to increase (decreasing CI) with increasing joint angle. In ten healthy subjects measured with magnetic resonance (MR) images, the patellofemoral joint became significantly more congruent as the knee angle increased from 15 deg to 45 deg using method M5. The magnitude and variability of the patellofemoral CI was dependent on the surface representation used, suggesting that standardization of the surface representation is important to provide a consistent measure. Specifically, M5 provides a local measure of joint congruence, which can account for joint position and orientation. M5 balances the ability to detect differences in congruence between knee angles without introducing high variability.

Extracellular Vesicles in the Synovial Joint: Is there a Role in the Pathophysiology of Osteoarthritis?

The role of extracellular vesicles (EV) in osteoarthritis has become the focus of much research. These vesicles were isolated from several cell types found in synovial joint including chondrocytes and synovium. As articular cartilage is an avascular tissue surrounded by synovial fluid, it is believed that EV might play a crucial role in the homeostasis of cartilage and also could hold key information in the pathogenesis of osteoarthritis. This is thought to be due to activation of pro-inflammatory factors leading to a catabolic state and degradation of cartilage. In addition, due to the nature of articular cartilage lacking neuronal innervation, knowledge of EV can contribute to identification of novel biomarkers in this debilitating condition. This can be either directly isolated from aspirate of synovial fluid or from peripheral blood. Finally, EVs are known to shuttle important signalling molecules which can be utilised as unique modality in transferring therapeutic compounds in a cell free manner.

The increasing incidence of infantile hypertrophic pyloric stenosis.

Several reports have suggested that there is an increasing incidence of infantile hypertrophic pyloric stenosis (IHPS). We examined the incidence of IHPS in a stable population in the West of Ireland over a ten year period (1981-1990). During the 10 years of the study the number of live births per year did not alter significantly. The incidence of IHPS increased significantly from 0.87/1000 live births in 1981 to 5.10/1000 in 1990 (p < 0.001, Student's test), peaking in 1989 at 6.8/1000. There was no statistical correlation between the increasing incidence and feeding habits, birth rank, family history or gender distribution. The reason(s) for this increase remain unclear.

Differences in patellofemoral contact mechanics associated with patellofemoral pain syndrome.

Patellofemoral pain syndrome (PFPS) is a disorder of the patellofemoral (PF) joint in which abnormal tracking is often cited as a factor in pain development. PF tracking is partially dependent on passive stabilizers (ex: PF geometry). Relations amongst PFPS, PF tracking, and contact mechanics are poorly understood. In-vivo investigation of passive PF joint stabilizers including PF tracking, contact mechanics, cartilage thickness, and patellar shape will allow structural characterization of the PF joint and may highlight differences associated with PFPS. This study examined the role that passive stabilizers play in PFPS (n=10) versus healthy subjects (n=10). PF tracking (contact area centroid migration), cartilage thickness, shape, congruence, and contact patterns were quantified using magnetic resonance imaging during isometric loading at 15 degrees , 30 degrees , and 45 degrees of knee flexion. Distinct relationships were identified between patellar shape and tracking and contact, particularly at low flexion (15-30 degrees ). Healthy subjects exhibited distinct PF tracking and contact patterns related to Type I patella shape (80%) with increasing total contact area (p<0.001) and proximal centroid migration (15-30 degrees p=0.012; 30-45 degrees p<0.001) for increasing knee angles. PFPS subjects deviated from these patterns at low flexion, demonstrating higher total contact area than healthy subjects (p=0.046 at 15 degrees ), lack of proximal centroid migration (15-30 degrees ), and more Type II (30%) and III (20%) patella shapes. This study highlights a new finding that patellar shape combined with low degrees of flexion (15-30 degrees ) may be important to consider, as this is where PFPS tracking and contact patterns deviate from healthy.

Lumbar punctures, meningitis, and persisting pleocytosis.

A retrospective survey of children with haemophilus and pneumococcal meningitis was carried out to assess the significance of persistent CSF pleocytosis and the need for repeat lumbar punctures after adequate treatment. Persistent pleocytosis was noted in 9 of 27 patients with haemophilus meningitis; this tended to be present in those with higher initial CSF white blood counts and lower initial CSF glucose contents. No sequelae were noted in those with persistent pleocytosis. Repeat lumbar punctures were not of clinical benefit and tended to result in longer treatment which was not warranted.

Ramstedt's pyloromyotomy: a specialist procedure?

One hundred and twenty infants with infantile hypertrophic pyloric stenosis were operated on by two consultant general surgeons over a 13-year period. General anaesthetic and a standard surgical approach was used in all cases. No mortality was recorded and there were no wound dehiscences. The overall postoperative wound infection rate was 9.2%. Prior to 1985 the infection rate was 15%. Following attention to a number of details including care of the umbilicus, the incidence decreased after 1985 to 4%. The most common postoperative complication was vomiting, which occurred in 25% of infants. There was one negative laparotomy in the 13-year study period. Two children required a second procedure for persistent vomiting. The argument in favour of specialisation in managing this condition is questioned along with the need for intensive diagnostic investigation.