[Treatment of extensor mechanism rupture after total knee arthroplasty]. / Behandlung der Strecksehnenruptur bei liegender Knietotalendoprothese.

Disruption of the extensor mechanism is one of the most devastating complications in knee arthroplasty with a reported incidence between 0.17 and 2.5 %. Due to a high rate of subsequent complications and poor clinical results, every effort should be made to avoid extensor mechanism disruption. In cases of disruption however, the orthopaedic surgeons must be aware of non-operative and surgical treatment options and their indications, timing, outcome and limitations. Non-operative treatment is feasible in cases of incomplete disruption of the quadriceps tendon with an extension deficit of less than 20°. Complete disruption of the quadriceps tendon or rupture of the patellar tendon should be treated operatively. Therapeutic strategies include direct repair of the tendon in acute disruption without retraction. Retraction as well as soft tissue damage necessitates augmentation of the tendon. Frequently used endogenous augments are the semitendinosus tendon as well as the gastrocnemius muscle. Exogenous options are allografts of the Achilles tendon or structured extensor mechanism grafts and synthetic augments to support endogenous tendon repair. The clinical results after extensor mechanism failure following total knee arthroplasty are less favourable compared to ruptures in native knee joints. The most common complications are postoperative stretching and the maintenance of an active extensor lag.

[Does the body mass index influence the results of revision total knee arthroplasty?]. / Hat der Body-Mass-Index Einfluss auf das Ergebnis nach Knieendoprothesenwechseln?

BACKGROUND: Revision total knee arthroplasty (TKA) is one of the most demanding as well as increasing orthopaedic operations. The influence of a higher body weight or body mass index (BMI) on the results of revision TKA is not evident so far. We therefore hypothesised that obesity as well as a high body weight could influence the results of revision TKA. PATIENTS: 75 consecutive revision TKA in 75 patients were included and stratified according to a BMI greater or smaller than 30 kg/m2 and a body weight greater or smaller than 90 kg. The Knee Society score (KSS), the function and the knee subscales were analysed pre- and postoperatively as well as the pre- to postoperative improvement. The duration of the procedure, the occurrence of complications, the blood loss and the length of hospital stay were collected. RESULTS: All patients showed a significant improvement of the KSS and function score (p < 0.05). There was a tendency to superior results in patients with a smaller BMI and a lower body weight. This tendency was most pronounced in the function subscale which depicted significant differences in favour of a BMI smaller 30 kg/m2. No significant differences were observed in the other analysed factors. CONCLUSION: BMI greater than 30 kg/m2 as well as a higher body weight seem to negatively influence the function of revision TKA. However, all patients significantly improved after revision TKA and no differences were found according to the occurrence of complications. Therefore, revision TKA should not be refused to obese or heavy patients.

[Validity of digital templating in total hip arthroplasty: impact of stem design and planner's experience]. / Validität der computergestützten Hüfttotalendoprothesenplanung: Einfluss von Schaftdesign und Untersuchererfahrung.

INTRODUCTION: Preoperative planning in total hip arthroplasty decreases the risk of implant oversizing and facilitates intraoperative orientation. The size of the acetabular and femural components can be estimated. The aim of the present study was to determine the validitiy of digital templating. Furthermore, we compared the accuracy of three planners with different clinical experience and the effect of two different femoral component designs on planning accuracy. METHODS: On 60 a. p. pelvis radiographs, 60 unilateral, non-cemented total hip arthroplasties using the planning tool "AGFA-Orthopaedic-Tools Version V2.10®" (Fa. Agfa Health Care, Mertsel, Belgium) were repeatedly planned by three orthopaedic surgeons (planner A fifth year, planner B third year, planner C second year of training). All 60 patients received pressfit acetabular components, a straight stem was implanted in 28 (CLS-Spotorno™, Fa. Zimmer) and a short stem (Fitmore™, Fa. Zimmer) in 32 patients. The planned sizes of the components and the offset-variations were compared to the implanted sizes. RESULTS: The percental accuracy and ICC planning for the straight stem were 42.9 %/0.906 for planner A, 39.3 %/0.833 for planner B, and 28.6 %/0.836 for planner C. Planning the short stem, the percental accuracy and ICC were 34.4 %/0,886 for planner A, 21.9 %/0.708 for planner B, and 12.5 %/0.681 for planner C. The accuracy and ICC of templating the acetabular components were 35 %/0.796 for planner A, 30 %/0.725 for planner B, and 26.8 %/0.511 for planner C. Planning the sizes of both femoral components showed significant differences between planner A and C and planner B and C in Wilcoxon's signed-rank test. CONCLUSION: A lower level of experience showed no effect on the planning results of the acetabular components, but there were considerable and significant differences on planning the femoral components. Furthermore, the design of the femoral component had an impact on planning accuracy.

[Approval of a bone bank: an institution's experience]. / Zulassung einer klinikeigenen Knochenbank : Ein Erfahrungsbericht.

The new tissue laws of 2007 created a completely new situation for German musculoskeletal tissue banks. The objective of the new regulations in the recent German tissue act is to improve safety by reducing the risk of transmission of viral and nonviral diseases. Since 2007 tissue banks have to declare their intention to continue providing allografts to the local authorities until August 2011 based on the guidelines of the Federal Medical Association (Bundesärztekammer 2001) and according to § 144 of the Pharmaceutical Products Act (Arzneimittelgesetz). The Orthopedic University Clinic in Ulm applied for registration according to § 20 b and c of the Pharmaceutical Products Act in 2010. After submitting all the required documents, government officials controlled the equipment, distribution of responsible personnel, location of operating theatres and the laboratory and quality assurance documentation. After alluding to the lack of validation for the use of a hemoculture medium for testing ringer lactate solutions, permission according to § 20 b and c was granted with the obligation to transfer all serological and microbiological testing of tissue donors to another laboratory with its own approval under § 20 c of the Pharmaceutical Products Act.

[Minimally invasive total hip arthroplasty - trend or state of the art?: A meta-analysis]. / Minimalinvasive Hüftendoprothetik - nur Trend oder schon Standard?: Eine Metaanalyse.

Minimally invasive approaches in total hip arthroplasty are being used worldwide and continue to grow in popularity. Despite early reports of catastrophic failures, both the number of scientific publications as well as the number of orthopaedic surgeons practicing minimally invasive techniques in total hip arthroplasty are steadily increasing. By means of a systematic review of the literature, the current article weighs the potential advantages and disadvantages of minimally invasive techniques. A shorter skin incision, potentially less muscle damage, a faster rehabilitation and a clinically irrelevant lower blood loss may support the use of minimally invasive techniques. However, the potential impairment of wound cosmetics, the increased risk of periprosthetic fractures, implant malpositioning and lack of long-term results contradict the use of minimally invasive total hip arthroplasty as a standard treatment.