[The infected implant]. / Das infizierte Implantat.

The periprosthetic infection is a permanent risk and a severe complication in joint arthroplasty. Raising numbers of cases, unsatisfactory results of treatment and high cost urge to sufficient prophylactic behaviour in primary surgery and research for new treatment strategies. In the future antibiotic coating of the implants and influence on biofilm could possibly be established. Disciplined early diagnostic measures and rational actions following the established concepts are able to create better results and reduce the extreme high costs.

[Epidemiology and pathophysiology of rotator cuff tears]. / Epidemiologie und Pathophysiologie der Rotatorenmanschettenrupturen.

Tears of the rotator cuff are one of the most common injuries to any tendon in the human body. Various theories and observations have since been made as to the origin of these tears. It is now commonly accepted to distinguish between"extrinsic" and"intrinsic" causes. Extrinsic describes an attrition which might have been caused by a subacromial bony conflict, while intrinsic changes originate within the tendon body itself due to age-related degenerative changes, giving rise to partial and later complete rupture of the tendon body. A better understanding of the underlying pathophysiological mechanism will make it easier for the attending orthopedic surgeon to decide whether a more conservative or operative course will have the best outcome for the situation given.

Is "aseptic" loosening of the prosthetic cup after total hip replacement due to nonculturable bacterial pathogens in patients with low-grade infection?

BACKGROUND: Loosening of the prosthetic cup is the limiting factor in the service life of total hip prostheses (THPs). Despite effective culture methods, the detection of low-grade infection in patients with loose implants still presents a challenge. It is crucial to distinguish between "aseptic" loosening and loosening due to periprosthetic infection, so that appropriate treatment can be administered. We investigated whether aseptic loosening of the acetabular components of THPs is due to unrecognized infection. METHODS: From October through December 2002, a total of 24 patients with acetabular cup loosening were investigated. Only patients without clinical signs of infection and with negative results of bacteriologic culture of synovial fluid (obtained by preoperative aspiration) were included in the study. Intraoperative biopsy samples obtained from the neocapsule and synovia (e.g., the interface membrane) were examined by means of routine culture methods and by polymerase chain reaction (PCR) for detection of 16S ribosomal RNA (rRNA). Control subjects included 9 patients undergoing primary hip arthroplasty. RESULTS: C-reactive protein levels and erythrocyte sedimentation rates were slightly elevated in the group with loosening, compared with the control group, but the difference was not statistically significant. PCR and routine culture showed no microorganisms in either group, with the exception of 1 patient in the loosening group. CONCLUSIONS: PCR for detection of 16S rRNA in tissue specimens obtained from hip joints is not superior to routine bacteriologic culture techniques for detection of low-grade infections. However, these results demonstrate that the loosening of cups in THPs do not usually result from nonculturable periprosthetic infection, if the microbiological processing is adequate.

[One-stage revision of shoulder arthroplasty in the case of periprosthetic infection]. / Einzeitiger Schulterendoprothesenwechsel bei periprothetischer Infektion.

AIM: Infection of shoulder arthroplasties is rare, but represents a potentially devastating complication. The aim of this work is to show the value of various diagnostic procedures, specify causative pathogens and present the results of one-stage revised patients. METHOD: We performed a retrospective analysis of our 16 consecutive patients with an infected shoulder arthroplasty. RESULTS: In 13 of 16 cases a causative pathogen could be established preoperatively. Staphylococcus and Propioni spp. dominated. Only 9 patients could be followed up because two died, two were lost and three patients were revised because of non-infectious complications. The follow-up time was 5.8 years (13 months-13.25 years). The Constant-Murley score was 33.6 of 100. Eradication of infection was achieved in all patients. In the follow-up time no reinfection has occurred. CONCLUSION: Culturing of the preoperative joint fluid aspirate and the determination of CRP provide an early diagnosing of shoulder arthroplasty infection. One-stage revision arthroplasty with radical debridement and application of antibiotics to the bone cement provide an accurate therapy of periprosthetic shoulder infection.

Spontaneous hemarthrosis of the knee associated with clopidogrel and aspirin treatment.

We report a case of a 76-year-old-man who developed spontaneous hemarthrosis of his right knee following clopidogrel-aspirin treatment. Clopidogrel is an ADP receptor antagonist and in combination with aspirin widely used in patients with atherosclerotic vascular disease to reduce the incidence of ischemic events. To date, no case of spontaneous hemarthrosis following clopidogrel-aspirin therapy has been reported. Prompt aspiration after discontinuing the ADP receptor antagonist-aspirin combination therapy can assist early diagnosis and may prevent further damage to the joint. In conclusion, spontaneous hemarthrosis is a possible complication following clopidogrel-aspirin therapy and is recommended to be evaluated when appropriate clinical symptoms (e.g., intraarticular effusion) present.

[Intermediate term outcome of of a hip prosthesis revision system]. / Mittelfristige Ergebnisse mit einem Hüftschaftrevisionssystem.

The Zweymüller shaft for uncemented total hip arthroplasty was developed in the early 1970s. Encouraged by the clinical results with this stem, which was mainly used in primary arthroplasty, longer fitting stems were added to the line to accommodate bony defects and to allow for an optimal load transfer from proximal to distal. The principal of the design is to allow an optimal distal fixation while allowing the bone to remodel in the proximal part. This study reports on 89 patients who underwent revision surgery of the hip for mostly aseptic loosening. The results after a median follow-up of 36 months show an increase of the modified Harris hip score from 52 points pre- to 82 points postoperatively. Radiographic subsidence was found in nine cases, with eight having progressed for more then 3 mm. Postoperative complications occurred in 11.2%, with seven dislocations. Open revision became necessary in two cases. The stem reviewed here seems to achieve predictable results in cases where a proximal cone is still present to facilitate load transfer, while at the same time the quadrangular stem provides solid distal fixation and ensures rotary stability.

Detection of Staphylococcus aureus and Staphylococcus epidermidis in clinical samples by 16S rRNA-directed in situ hybridization.

Staphylococcus epidermidis and Staphylococcus aureus are the most common causes of medical device-associated infections, including septicemic loosenings of orthopedic implants. Frequently, the microbiological diagnosis of these infections remains ambiguous, since at least some staphylococci have the capacity to reduce their growth rate considerably. These strains exhibit a small-colony phenotype, and often they are not detectable by conventional microbiological techniques. Moreover, clinical isolates of S. aureus and S. epidermidis adhere to polymer and metal surfaces by the generation of thick, multilayered biofilms consisting of bacteria and extracellular polysaccharides. This study reports improved detection and identification of S. aureus and S. epidermidis by an in situ hybridization method with fluorescence-labeled oligonucleotide probes specific for staphylococcal 16S rRNA. The technique has proven to be suitable for the in situ detection of staphylococci, which is illustrated by the identification of S. epidermidis in a connective tissue sample obtained from a patient with septicemic loosening of a hip arthroplasty. We also show that this technique allows the detection of intracellularly persisting bacteria, including small-colony variants of S. aureus, and the differentiation of S. epidermidis from other clinically relevant staphylococci even when they are embedded in biofilms. These results suggest that the 16S rRNA in situ hybridization technique could represent a powerful diagnostic tool for the detection and differentiation of many other fastidious microorganisms.

[Shoulder joint instability after primary arthroplasty]. / Schulterinstabilität nach primärem Schultergelenkersatz.

Instability is one of the most common complications after shoulder arthroplasty. The literature cites subluxation or luxation to occur between 0% and 38% in various studies. Instabilities may present either as subluxation or frank dislocation, and may be directed in an anterior, posterior, inferior or, depending on the state of the rotator cuff, cranial direction. The stability of any shoulder joint is given by the balance of the muscles directing the forces around the shoulder joint in association with the passive stabilizers of the shoulder joint capsule as well as the bony contours between glenoid and humeral head. Any disturbance of this delicate balance will lead the shoulder into instability, particular so if bony erosion patterns such as posterior glenoid wear in osteoarthritics will develop subluxation early on. Therefore implantation of any prosthesis is required to be done in the appropriate version as to avoid secondary instability through the prosthetic components. In the study undertaken here instability was found to be the most common complication in 44 shoulder revision surgeries. The result with an average Score of 41.9 recorded after Constant demonstrates that the excellent and good results obtained with primary arthroplasties can not be expected in revision surgery. Posterior instability may be present just as well as the more easily observed anterior instability. Separate to frank luxation or instability is the late cranialisation of the rotator cuff deficient shoulder which, although resulting in many cases in superior anterior subluxation, will mostly be seen as a late complication after arthroplasty.

Shoulder instability after primary shoulder joint replacement.

Instability is one of the most common complications after shoulder arthroplasty. The literature cites subluxation or luxation to occure between 0 % and 38 % in various studies. Instabilities may present either as subluxation or frank dislocation, and may be directed in an anterior, posterior, inferior or, depending on the state of the rotator cuff, cranial direction. The stability of any shoulder joint is given by the balance of the muscles directing the forces around the shoulder joint in association with the passive stabilizers of the shoulder joint capsule as well as the bony contours between glenoid and humeral head. Any disturbance of this delicate balance will lead the shoulder into instability, particular so if bony errosion patterns such as posterior glenoid wear in osteoarthritics will develop subluxation early on. Therefore implantation of any prosthesis is required to be done in the appropriate version as to avoid secondary instability through the prosthetic components. In the study undertaken here instability was found to be the most common complication in 44 shoulder revision surgeries. The result with an avarage Score of 41.9 recorded after Constant demonstrates that the excellent and good results obtained with primary arthroplasties can not be expected in revision surgery. Posterior instability may be present just as well as the more easily observed anterior instability. Separate to frank luxation or instability is the late cranialisation of the rotator cuff deficient shoulder which, although resulting in many cases in a superior anterior subluxation, will mostly be seen as a late complication after arthroplasty.

The microvascular pattern of the supraspinatus tendon.

The vascular pattern of the supraspinatus tendon was studied in 18 human anatomic specimens. The ages of the specimens ranged from 26 to 84 years. Selective vascular injection with a silicon-rubber compound allowed visualization of the vascular bed of the rotator cuff and humeral head. The presence of a hypovascular or critical zone close to the insertion of the supraspinatus tendon into the humeral head was confirmed. However, only a uniformly sparse vascular distribution was found at the articular side, as opposed to the well-vascularized bursal side. This was also confirmed with histologic sections of the tendon. The poor vascularity of the tendon in this area could be a significant factor in the pathogenesis of degenerative rotator cuff tears.