Patellar dislocation is one of the commonest knee injuries in adolescents. Although treatment usually leads to good results, the influence of anatomical and functional factors on therapeutic strategy has been underestimated, especially in cases of recurrence. The course of treatment has been analysed in 88 patients with 136 patellar dislocations. The importance of anatomical conditions was studied using X-ray and MRI findings. The treatment results were critically evaluated in comparison with current recommendations. From 2000 to 2015, 109 patellar dislocations occurred in 88 patients; a further 27 previous dislocations were reported by the patients (mean age 14 years, 47 boys and 41 girls). About one-third of patients (35.2 %) suffered one or more recurrences. Almost half (48.6 %) of the dislocations occurred during physical exercise, particularly ball sports. Osteochondral flake fracture was found in 9 % of the patients, and a lesion of the medial patellofemoral ligament in 96 %. There was an anatomical predisposition to patellar dislocation in almost all cases. The sulcus angle, patellar and trochlear dysplasia, and patellar height were highly significantly different between the patient group and controls. The TT-TG distance was subsequently calculated, but had no impact on therapy. Seventy-seven patients were treated conservatively and 32 patients surgically. The conservative procedure included partial immobilisation for six weeks. Surgical reconstruction or tightening was performed in 27 cases; in five, in combination with other surgical procedures. Plasty of the medial patellofemoral ligament with a tendon graft was performed in five patients, and osteochondral or meniscal lesions were repaired in 10 patients. Recurrences occurred in 41.7 % of conservatively treated knees and in 29.6 % of surgically treated knees (without reconstruction with a tendon graft). No recurrence was seen after reconstruction of the medial patellofemoral ligament with a tendon graft. Fifty-four patients underwent a follow-up examination. Fourteen of these (25.9 %) had suffered a recurrence. The outcome 16 months after the end of treatment was mostly good, as were the results of self-assessment (Larson-Lauridsen Score). An anatomical predisposition is detectable in almost all cases of patellar dislocation, but frequently occurs with an accident event, e.g. in ball sports. Primary patellar dislocations without serious concomitant injuries may be treated conservatively. In the event of recurrence, the indication for surgery is given, even in young patients and in any patient with an osteochondral flake fracture. Tightening reconstruction of the MPFL used to be frequently performed, but is associated with a high rate of recurrence.

Superantigens were suggested to play a role in the pathogenesis of different autoimmune diseases including multiple sclerosis (MS). Previously, it was demonstrated that local expression of the superantigen, staphylococcal enterotoxin A (SEA) in the brain of rats may lead to encephalitis which was amplified by using intravenous injection of concanavalin A (ConA)‐activated splenocytes. In the present investigation, gene expression was studied in the rat brain 8 days after an injection of 50 μl of 1 mg/ml SEA or saline and 5 days after an intravenous injection of 1 × 107 ConA‐activated spleen cells. Of 8800 genes investigated (Affymetrix, rat genome U34A), the expression of 106 genes was significantly and at least threefold increased with SEA, while the expression of 29 genes was decreased at least threefold. Increased gene expression was compatible with an intracerebral inflammatory response mediated by antigen‐presenting cells and CD8+ T lymphocytes. Elevated chemokines comprised RANTES (CCL5), osteopontin, MCP‐1 (CCL2) and CXCL10. Further, genes with increased expression were assigned to the extracellular matrix, microglia/macrophage cell elements, astrocytes (GFAP) and phagocytosis. There was considerable conformity between previously reported gene expression profiles for experimental autoimmune encephalomyelitis (EAE) or MS and the present findings. Our data are in line with the concept that T‐cell superantigen locally expressed in the central nervous system induces an inflammatory response. Therefore, the study of gene expression profiles does not seem to allow clear conclusions with respect to the aetiology of central nervous system autoimmune diseases.

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The pathogenesis of rheumatoid arthritis (RA) is incompletely understood. Human endogenous retroviruses (HERVs) and their superantigenic envelope protein (env) have been implicated in the pathogenesis of RA. In the present investigation, the arthritogenic potential of the superantigen staphylococcal enterotoxin A (SEA) has been investigated. In the present investigation, the bacterial superantigen staphylococcal enterotoxin A (SEA) was injected into the right knee joint of 15 Lewis rats. Further nine animals received saline. Animals were sacrificed one, five and 10 days after the injection, respectively. The antigens CD3, CD4, CD8, MHC class I, MHC class II, Pax5 and CD138 were investigated by immunohistochemistry on cryo-sections. After intra-articular SEA injection, the inflammation was initially dominated by CD8+ T cells. In the course of the investigation, the numbers of CD4+, Pax5+, CD138+ and MHC class II+ cells increased. CD3 was expressed in low numbers as compared to CD8. After saline injection, no similar inflammatory response has been detected. The arthritis induced by the superantigen SEA may be a novel model for inflammatory joint diseases, that is rheumatoid arthritis or juvenile idiopathic arthritis.

No abstract