[Pathological findings and therapy for anterior knee pain following total knee arthroplasty]. / Ursachen und Therapie des vorderen Knieschmerzes nach Knieendoprothetik.

INTRODUCTION: An incidence of 10 % for anterior knee pain following total knee arthroplasty has been published. Often several factors can be found leading to functional deficits following total knee arthroplasty. The aim of our study on a consecutive series of revised total knee arthroplasties due to anterior knee pain is to show the pathological findings and their therapy. PATIENTS AND METHOD: Between January 1, 2006 and March 31, 2007 13 revisions including 2 men and 11 women due to anterior knee pain following total knee arthroplasty were performed. Mean duration between index operation and revision was 13.2 months. RESULTS: In all cases lateralisation of the patella often accompanied by hypertrophy of the lateral facet could be detected. In one case severe medial and lateral instability of the collateral ligaments was found. A meniscoid could be described in 2 cases. In one additional case malpositioning of the tibial component could be found. After resection of the hypertrophic lateral patellar facet and lateral release and therapy for additional pathologies all patients were free of complaints after a mean follow-up of 9 months. CONCLUSION: For avoiding anterior knee pain following total knee arthroplasty an exact positioning of both the femoral and the tibial component is essential. Additionally stable collateral ligaments and exact gliding of the patella by means of the "no thumb sign" should be achieved, too. During the operation hyperextension of 5 degrees is essential. If, intraoperatively, a hypertrophic lateral patellar facet is detected we recommend its resection.

[Prevalence of allergic reactions to implant materials in total hip and knee arthroplasty]. / Häufigkeit von Allergien gegen Implantatwerkstoffe in der Hüft- und Knieendoprothetik.

INTRODUCTION: Several case reports have been published on allergic reactions like eczema, urticaria, persistent swelling, sterile osteomyelitis or aseptic implant loosening in the context of orthopaedic implants. There is, however, a lack of data concerning incidence or prevalence of allergies in this special group of patients. The aim of this study was to analyse a consecutive series of patients with a total hip or knee arthroplasty to gain information about prevalence of allergic reactions to constituents of the alloys or bone cement. MATERIAL AND METHOD: Between February and September 2005, a consecutive series of 300 patients after total hip (THA) or total knee (TKA) arthoplasty were interviewed during regular follow-up using the standardised questionnaire of the working group 20 "Implant and Allergy" of the DGOOC with respect to allergies, especially to different metals or constituents of bone cement. In this study 100 males and 200 females with 214 THA and 86 TKA were included. The mean follow-up time was 33.3 months (min: 3, max: 174). RESULTS: Different allergies were found in 39 patients. In 12 cases (4 %) allergic reactions against nickel, in 4 cases (1.3 %) against cobalt, in 2 cases (0.7 %) against chromium and in 2 cases (0.7 %) against benzoyl peroxide were detected by means of epicutaneous testing. One patient each suffering from a nickel allergy showed signs of osteolysis or recurrent effusion after THA with a metal-on-metal bearing. One patient each suffering from recurrent effusion or eczema following TKA showed allergic reactions to benzoyl peroxide. In all the other patients with allergies to the alloy constituents, the follow-up was uneventful. CONCLUSION: The prevalence of allergic reactions in an unselected group of orthopaedic patients is significantly lower in comparison to that in dermatological studies. Most patients suffering from allergies tolerated the implant uneventfully. Further studies are needed to identify those groups of patients with allergies who may not tolerate the implant in order to provide better care or use special implants.

[Recurrent effusion and granulomatous synovitis following total knee arthroplasty in association with latex allergy]. / Rezidivierende Ergussbildung und granulomatöse Synovitis nach Knietotalendoprothesenimplantation bei Latexallergie.

An increasing number of articles report about allergic reactions in association with total knee arthroplasty. While most studies focus on allergic reactions to metallic components, few reports exist about reactions to bone cement or its ingredients. Allergy to natural rubber latex is a major occupational problem in the health care sector and a problem even in other occupations in which protective gloves are used. The allergic reaction to latex ranges from a minor skin rash to anaphylactic shock. Preventing exposure to latex is the key to managing and preventing this allergy. We report about a patient who developed recurrent effusion and granulomatous synovitis following total knee arthroplasty in association with latex allergy.

[Atraumatic dislocation in mobile-bearing total knee arthroplasty: two case reports]. / Atraumatische Dislokation von Knietotalendoprothesen mit Mobile-bearing - 2 Falldarstellungen.

INTRODUCTION: Atraumatic dislocation following total knee arthroplasty (TKA) is a rare condition. Severe complications after dislocation are lesion of the vascular-nerve bundle, compartment syndrome or amputation. The benefit of TKA with mobile-bearing are an improvement of the range of motion and better articulation. In comparison to fixed-bearing TKA there is the risk of dislocation or breakage of the polyethylene insert. PATIENTS AND METHOD: We present two cases with dislocation following TKA with mobile-bearing. In both cases preoperatively there was a significant weakening of the function of the quadriceps muscle. During revision of the TKA severe damage with multiple scratches of the polyethylene onlay could be detected. The damage of the PE onlay could especially be found at the tibial aspect. Follow-up showed an uneventful course after conversion to fixed-bearing polyethylen component. CONCLUSION: In cases of dislocation following TKA with mobile-bearing operative revision is recommended to exchange the damaged PE onlay and prevent increased wear. TKA with mobile-bearing should be reserved only for cases with a good quadriceps muscle function.

[Osteochondritis dissecans of the head of the talus: a case report]. / Osteochondrosis dissecans des Taluskopfes - Eine Falldarstellung.

Incidence of osteochondritis dissecans of the talus (ODT) ranges to 0.9 %, most often located in the region of the dorsomedial aspect of the talar dome. ODT is frequently discussed as a sequel of trauma. We present the rare case of a 30 year young patient suffering from ODT of the talar head without history of trauma. Revision of the talonacvicular joint and excision of the stage 3 lesion according to Berndt and Harty and microfracturing were performed. Since the operative procedure the patient is free of any complaints.

[Pathogenesis of hip osteoarthritis]. / Pathogenese der Hüftgelenksarthrose. Von der Fehlbelastung zum Verschleiss.

Coxarthrosis is the most frequently occurring hip disease, is the most common type of osteoarthritis in general and is the second most frequent cause of chronic invalidity. Causes are inherited hip diseases (e.g. dysplasia), growth diseases (e. g. Perthes' disease, slipped capital femoral epiphysis), injuries (fractured femur, fractures of the femoral head or acetabulum, necrosis of the femoral head), and inflammatory, rheumatic or metabolic diseases. Hip deformities such as hip dysplasia or protrusio acetabuli lead to increased mechanical deterioration as a result of the pathological anatomy and hence to a chronically progressing degeneration (coxarthrosis). Primary coxarthrosis usually begins between the 50th and 60th year of life; the secondary disease can develop even earlier depending on cause.