Our aim was to investigate vascular endothelial growth factor (VEGF) expression after lacerations of a meniscus in a rabbit model. Specimens of meniscus were examined using immunohistochemistry, enzyme-linked immunoassay and the reverse transcription polymerase chain reaction after one, two, five or ten weeks. In the periphery of the meniscus 90% of the lacerations had healed after five and ten weeks, but no healing was observed in the avascular area. Expression of VEGF protein and VEGF mRNA was found in the meniscus of both the operated and the contralateral sites but both were absent in control rabbits which had not undergone operation. The highest expression of VEGF was found in the avascular area after one week (p < 0.001). It then lessened at both the vascular and avascular areas, but still remained greater in comparison with the control meniscus (p < 0.05). Despite greater expression of VEGF, angiogenesis failed at the inner portion. These findings demonstrated the poor healing response in the avascular area which may not be caused by an intrinsic cellular insufficiency to stimulate angiogenesis.

Aims: Although the glenohumeral joint is the most mobile articulation of the human body it is known to exhibit ball-and-socket-kinematics. Compression into the glenoid concavity keeps the humeral head centered. The purpose of this study was to determine the effects of joint position on glenohumeral stability through concavity-compression. Methods: Ten cadaver shoulders were tested. The glenoid was mounted horizontally onto a six-component load cell while the humerus was clamped to a vertically unconstrained slide. An x-y-stage translated the load cell with the glenoid underneath the humeral head in eight different directions. Compressive loads of twenty, forty and sixty Newtons were applied. The tests were repeated in 0, 30, 60 and 90 degrees of glenohumeral abduction with and without labrum. Translation distances and the forces resisting translation were recorded and the stability ratio calculated. Results: The average stability ratio was higher in hanging arm position than in glenohumeral abduction. With intact labrum the highest stability ratio was detected in inferior direction (59.8±7.7 percent), without labrum in superior direction (53.3±7.9 percent). In both conditions the anterior direction showed the lowest stability ratio (32.0±4.4 percent; 30.4±4.1 percent). Resection of the labrum resulted in a decrease in stability ratio of 9.6 ±1.7 percent. With increasing compressive load the stability ratio slightly decreased. Conclusions: Anterior shoulder dislocation may be facilitated by the lower stability in glenohumeral abduction and anterior direction. The labrum may not contribute as much as previously assumed to glenohumeral stability. Even moderate compressive forces are sufficient to provide stability through concavity-compression.

One of the advantage in using unicondylar prosthesis seems to be the preservation of the bone stock, which allows most often easily revision to a total knee replacement if required. The purpose of the study was to compare the patients outcome after revision of unicondylar prosthesis with a group of patients who have received total knee replacement primarily.

Material and Method: 28 patients after revision unicondylar prosthesis (group A) and 28 patients after primary total knee replacement (group B) were included in the study. The two groups were matched according to age, sex, weight, height, type of prosthesis and follow-up time. The patients’ evaluation was based on the Knee-Society-Score and the WOMAC-score. X-rays of the knee were taken in the AP weight bearing and lateral view.

Results: In group A the average follow-up time was 55±15 months and in group B 56±13 months. The knee-score showed 71.8±18 and 80.4±10.4 points and the function-score 56.1±15 and 62±19 points for group A and group B respectively without any statistical difference. The subjective assessment according to the WOMAC score showed difference in the functional outcome. A better range of motion of 110±11° was noticed for group B in comparison with group A 102±8° (p=0.004). The revised patients required a significantly higher poly-ethylene-inlay (12.9±3mm) compared to the primarily implanted ones (10.3±3mm) (p=0.004).

Discussion: Based on our findings revision of unicondylar to total knee replacement provides comparable results to primarily implanted total knee arthroplasty and should be considered for the treatment of unicompartmetal osteoarthritis even in younger patients, where a revision operation during lifetime is more likely. Despite the difference regarding the height of the inlay of 3mm, adequate bone stock was still found in order to implant an unconstraint type of knee prosthesis. The impaired functional outcome seems to be related to the fact of the reoperation and a significant longer history of osteoarthritis for group A in comparison with group B.