Experience with infected shoulder arthroplasty is limited. Treatment options are either one- or two-stage reimplantation, débridement with retention of the prosthesis, resection arthroplasty or arthrodesis. We retrospectively analysed ten patients with an infected shoulder prosthesis and evaluated the diagnostic and therapeutic management as well as the clinical outcome, assessed by the Constant score, Neer’s criteria and the mean abduction ability. We identified an infecting organism before surgery in nine patients. Four patients were treated by two-stage exchange reimplantation, five by resection arthroplasty and one underwent serial débridement combined with vacuum-irrigation therapy. Infection was eradicated in all patients of this series. The mean Constant score in resected patients was 32.7, in patients treated by stage exchange 40.1 (no difference) and we measured 90 points in the patient with retention of the implant. In patients treated by resection arthroplasty, merely the mean abduction yielded a better result (63 vs 31°) than in patients treated by two-stage exchange—with the pain level being identical in both groups. Treatment of infected shoulder implants in patients who often have to deal with concomitant diseases remains unsatisfactory. Two-stage exchange procedures yielded only slightly better functional results than resection arthroplasty, which should be considered in cases of elderly or chronically ill patients because it offers good pain relief. Serial débridement combined with irrigation therapy is a new method which offers good clinical results, however with an unknown risk of persisting infection. The authors recommend isolating the infecting organism prior to surgery to allow the administration of organism-specific antibiotics as early as possible during surgery in order to efficiently eradicate the infection.

The impact of infraglenoidal scapular notching in reversed total shoulder arthroplasty (RTSA) is still controversially discussed. Our goal was to evaluate its potential influence on subjective shoulder stability and clinical outcome. We hypothesized that subjective instability and clinical outcome after implantation of RTSA correlates with objective scapular notching.

Patellofemoral complications are one of the main problems after Total Knee Arthroplasty (TKA). Retropatellar pressure distribution after TKA can contribute to these symptoms. Therefore we evaluated retropatellar pressure distribution subdivided on the ridge, medial and lateral surface on non-resurfaced patella before and after TKA. Additionally, we analyzed axial femorotibial rotation and quadriceps load before and after TKA. Seven fresh frozen cadaver knees were tested in a force controlled knee rig before and after TKA (Aesculap, Tuttlingen, Germany, Columbus CR) while isokinetic flexing the knee from 20° to 120° under weight bearing. Ridge, medial and lateral retropatellar surface were defined and pressure distribution was dynamically measured while quadriceps muscles and hamstring forces were applied. Aside axial femorotibial rotation and quadriceps load was recorded. There was a significant change of patella pressure distribution before and after TKA (p = 0.004). In physiological knees pressure distribution on medial and lateral retropatellar surface was similar. After TKA the ridge of the patella was especially in higher flexion grades strongly loaded (6.09 +/−1.31 MPa) compared to the natural knee (2.92 +/−1.15 MPa, p < 0.0001). Axial femorotibial rotation showed typical internal rotation with increasing flexion both before and after TKA, but postoperatively it was significantly lower. The average amount of axial rotation was 3.5° before and after TKA 1.3° (p = 0.001). Mean quadriceps loading after implantation of knee prosthesis did not change significantly (575 N ±60 N in natural knee and after TKA 607 N ±96 N; p = 0.28). The increased retropatellar pressure especially on the ridge may be one important reason for anterior knee pain after TKA. The trochlea of the femoral component might highly influence the pressure distribution of the non-resurfaced retropatellar surface. Additionally, lower axial femorotibial rotation after TKA might lead to patella maltracking. Changing the design of the prosthesis or a special way of patella shaping might increase the conformity of the patella to trochlea to maintain natural contact patterns. Das patellofemorale Schmerzsyndrom stellt eines der zentralen Probleme in der Knieendoprothetik dar. Dabei wird angenommen, dass die retropatellare Druckverteilung nach Implantation einer Knietotalendoprothese (KTEP) zu dieser Symptomatik beiträgt. Wir untersuchten daher die retropatellare Druckverteilung unterteilt in First, mediale und laterale Rückfläche vor und nach KTEP. Zusätzlich analysierten wir die tibiofemorale Rotation und die Quadrizepszugkraft vor und nach KTEP. Die Simulation der Kniebewegung erfolgte an sieben humanen fresh-frozen Kniegelenken mit einem kraftgesteuerten Kniegelenkskinemator von 20° bis 120° Flexion mit programmierter Regelung unter konstanter isokinetischer Gewichtskraft an den Sehnen des M. quadriceps, M. semitendinosus und M. biceps femoris. Nach standardisierter Flächendefinition des Firstes, der medialen und lateralen Retropatellarfläche wurde die retropatellare Druckverteilung mittels Druckmessfolie vor und nach Implantation einer KTEP dynamisch gemessen. Zusätzlich wurden die tibiofemorale Rotation, sowie die Quadrizepszugkraft analysiert. Nach Implantation einer KTEP zeigte sich eine signifikante Änderung der retropatellaren Druckverteilung. Im natürlichen Kniegelenk war der retropatellare Druck medial und lateral gleichmäßig verteilt. Postoperativ zeigte sich bei höheren Flexionsgraden ein maximaler retropatellarer Druck besonders im Bereich des Patellafirstes (6,09 +/−1,31 MPa) im Vergleich zum natürlichen Kniegelenk (2,92 +/−1,15 MPa, p < 0,0001). Die axiale tibiofemorale Rotation zeigte die typische Innenrotation bei Flexion und Außenrotation bei Extension sowohl vor als auch nach Implantation einer KTEP; postoperativ war diese Rotation jedoch deutlich vermindert. Die durchschnittliche axiale Rotation betrug 3,5° vor und 1,3° nach KTEP-Implantation (p = 0,001). Die Quadrizepszugkraft änderte sich nach KTEP-Implantation nicht signifikant (575 N ±60 N beim natürlichen Knie und nach KTEP 607 N (±96 N), p = 0,28). Die Implantation einer KTEP führte in unserer Studie zu einer Steigerung des retropatellaren Drucks insbesondere im Firstbereich. Es ist davon auszugehen, dass durch die Erhöhung des retropatellaren Drucks und die ungünstigere Druckverteilung in vivo postoperative Patella Beschwerden entstehen können. Daneben kann die postoperativ verminderte Innenrotation der Tibia bei Flexion des Kniegelenkes zum Patella Maltracking führen. Wird bei der Implantation einer Knieprothese kein Retropatellarersatz durchgeführt ist ein standardisiertes knöchernes “Trimming” der Patella entsprechend dem Trochlea-Design der Prothese zu diskutieren.