[Long-term results after excision of a popliteal cyst]. / Langfristige Ergebnisse nach Exstirpation einer Poplitealzyse.

The objective was to evaluate long term results after removal of a popliteal cyst with special focus on recurrence rate and associated intraarticular pathology. Between 1982 and 1995 71 patients (23 women and 48 men between 21 and 75 years of age) underwent removal of a popliteal cyst. An additional arthroscopy of the knee joint was carried out in 51 consecutive patients starting in 1988. The mean follow up was 6.5 years (2 to 15 years), 66 patients (93%) were available. The subjective satisfaction with the outcome was assessed using a visual analogue scale (VAS) graded from 1 (highly satisfied) to 10 (highly dissatisfied). The popliteal region was evaluated by ultrasonography for recurrence of a cyst. During arthroscopy the predominant associated intraarticular pathologic finding was the lesion of the posterior horn of the medial meniscus (75%) and the lesion of the hyaline cartilage (90%). The cyst recurrence rate was 71%. In this subgroup grade III and grade IV chondral lesions were significantly more frequent (p < 0.001). Patients with a recurrence of the popliteal cyst rated the result significantly worse (7.6 +/- 2.3 vs. 3.4 +/- 2.3; p < 0.001). The recurrence rate was relatively high in the long term follow up. It depends strongly on the type of associated intraarticular pathology. Especially grade III and grade IV chondral lesions correlated significantly with recurrence of a popliteal cyst after removal. Therefore, the main goal of surgery should be the successful treatment of associated intraarticular pathologies.

Prevalence of popliteal cysts in children. A sonographic study and review of the literature.

Popliteal cysts in children differ from those in adults. They are considered to be less frequent and usually appear in the absence of intra-articular lesions. However, their prevalence in asymptomatic children is unknown. We present a prospective epidemiological study of 168 asymptomatic children under 15 years of age hospitalised for various pathologies. Children with knee problems and rheumatic diseases were excluded from the study. The children were examined ultrasonographically with a 7.5 MHz linear scanner. A popliteal cyst could be identified in 4 patients. The prevalence of asymptomatic popliteal cysts was thus 2.4%. For 2 of these patients, we obtained magnetic resonance image of the knee which showed no concommitant intra-articular pathology.

Sensitivity and optimal performance in steroid receptor analysis.

The application of various mathematical models for the identification of binding parameters in steroid receptor studies is discussed. In contrast to the usual statistical error considerations a deterministic error analysis based on the Euclidian norm and condition numbers is included. The predicted sensitivity behaviour with respect to data scattering is in good agreement with the experimental results.