[Hip dislocation following THA]. / Hüftluxation nach Hüftgelenktotalendoprothesenimplantation.

In the event of a hip dislocation following THA analysis of its mechanism is the main priority. In addition, the time since the operation and the direction of the dislocation need to be taken into account. When the cause of the dislocation is analysed the formation of the neocapsule plays a part at least in the case of early dislocations (within the first 6 weeks after the operation). Most dislocations happen during this postoperative period, and these can usually be treated nonoperatively by closed reduction with only a short period of general anaesthesia. Late dislocations (in the 7th and subsequent postoperative week) generally occur because of malpositioning or migration of the components of the prosthesis and quite often do need operative treatment. Dislocation after implantation of a total hip replacement is a serious complication; it should be treated quickly, and initially it confronts the operator with many unanswered questions, from the causes to their treatment.

[Influence of patellofemoral osteoarthritis on functional outcome after unicondylar knee arthroplasty]. / Einfluss der Retropatellararthrose auf das funktionelle Ergebnis nach unikondylären Schlittenprothesen.

BACKGROUND: Patellofemoral osteoarthritis is generally considered a contraindication for unicondylar knee arthroplasty. Therefore, even with an intact lateral compartment, bicondylar surface replacement is preferred when patellofemoral osteoarthritis is present, despite comparatively worse functional results. In the present study, the influence of patellofemoral osteoarthritis on the outcome of the Oxford III unicondylar implant was investigated. MATERIAL AND METHODS: The HSS and the patella score according to Turba were used to retrospectively evaluate the outcome of 44 Oxford III unicondylar implants at an average follow-up of 35 months. The degree of patellofemoral osteoarthritis was radiographically graded according to the Sperner score. RESULTS: The HSS score improved to an average of 92.3 points (68-99; p<0.001 vs preoperative score). With the patella score, only good and very good results were observed. At follow-up examination almost 70% of the knees showed patellofemoral osteoarthritis of degree III-IV. No correlation was found between the functional scores and the degree of patellofemoral osteoarthritis. CONCLUSION: Radiographic patellofemoral osteoarthritis seems to have no influence on the functional outcome of the Oxford III unicondylar knee arthroplasty. Therefore, unicondylar surface replacement is indicated even with radiographic evidence of patellofemoral osteoarthritis, provided that it is clinically asymptomatic.