R. Lenz

Response of human osteoblasts exposed to wear particles generated at the interface of total hip stems and bone cement

Aseptic loosening of total hip replacement is mainly caused by wear particles. Abrasive wear occurs at articulating surfaces or as a consequence of micro-motions at the interface between femoral stem and bone cement. Direct impact of wear particles on osteolysis, the remodeling of the bone stock and a directly affected function of osteoblasts was described. The present study examined the response of human osteoblasts exposed to different wear particles, which were generated in a test device providing oscillating micro-motions at the interface between femoral stem and standard bone cement. Characterization of released particles was performed by quantifying the size distribution and the metal content of the wear debris. Human osteoblasts were incubated with particles obtained from hip stems with different material compositions (Ti-6Al-7Nb and Co-28Cr-6Mo) and rough and smooth surface finishings combined with standard bone cement (Palacos(R) R) containing zirconium oxide particles. Commercially pure titanium particles (cp-Ti) and particulate zirconium oxide (ZrO(2)) were used for comparative analyses. The results revealed significant (p < 0.05) reduction of the cell viability after exposure to higher concentration of metallic particles, particularly from Co-based alloys. In contrast, ZrO(2) alone showed significantly less adverse effects on the cells. When increasing metallic particle concentrations massive inhibition was also observed in the release of cytokines including interleukine-6 (IL-6) and interleukine-8 (IL-8), but the expression of Procollagen I and the cell viability showed the highest reduction after exposure to Co-based alloy particles from rough stems.

Cell viability, collagen synthesis and cytokine expression in human osteoblasts following incubation with generated wear particles using different bone cements

In total hip arthroplasty, wear particles generated at articulating surfaces and interfaces between bone, cement and implants have a negative impact on osteoblasts, leading to osteolysis and implant loosening. The aim of this experimental study was to determine the effects of particulate wear debris generated at the interface between straight stainless steel hip stems (Exeter(®)) and three different bone cements (Palacos(®) R, Simplex™ P and Cemex(®) Genta) on cell viability, collagen synthesis and cytokine expression in human osteoblasts. Primary osteoblasts were treated with various concentrations of wear particles. The synthesis of procollagen type I and different cytokines was analysed, and markers for apoptosis and necrosis were also detected. The cytokine synthesis rates in the osteoblasts were initially increased and varied, depending on incubation time and particle concentration. Specific differences in the synthesis rates of interleukin (IL)‑6, IL-8, vascular endothelial growth factor (VEGF) and monocyte chemotactic protein-1 (MCP-1) were observed with the different bone cements examined. The negative effect of the particles on the synthesis of procollagen type I and increased rates of cell apoptosis and necrosis were observed with all three cements analysed. Our present data suggest that wear particles from the interface between the total hip stem and bone cement have a significant effect on viability, cytokine expression and collagen synthesis in human osteoblasts, depending on the bone cement used.

Arthroskopische Resektion des Akromioklavikulargelenks

OBJECTIVE Arthroscopic resection of the painful and degenerative altered acromioclavicular (AC) joint without destabilization of the joint and therefore pain relief and improvement in function. INDICATIONS Conservative failed therapy of painful AC joint osteoarthritis. Impingement caused by caudal AC joint osteophytes. Lateral clavicular osteolysis. CONTRAINDICATIONS General contraindications (infection, local tumor, coagulation disorders), higher grade instability of the AC joint (resection only together with stabilization). SURGICAL TECHNIQUE Diagnostic glenohumeral arthroscopy. Treatment of accompanying lesions (subacromial impingement, rotator cuff, long head of biceps). Subacromial arthroscopy with bursectomy (partial) and visualization of the AC joint. Resection of caudal osteophytes. Localization of the anterior portal using a spinal needle in the outside-in technique. Resection of 2-3 mm of the acromial side and the 3-4 mm of the clavicular side with shaver/acromionizer. RESULTS An isolated open AC joint resection was performed in 9 studies and an arthroscopic resection in 6 studies. Good and very good results were obtained in 79% (range 54-100%) in open resection and 91% (range 85-100%) in arthroscopic resections. Patients were able to return to activities of daily life more quickly after arthroscopic resections than after open surgery.

Arthroscopic resection of the acromioclavicular joint

OBJECTIVE Arthroscopic resection of the painful and degenerative altered acromioclavicular (AC) joint without destabilization of the joint and therefore pain relief and improvement in function. INDICATIONS Conservative failed therapy of painful AC joint osteoarthritis. Impingement caused by caudal AC joint osteophytes. Lateral clavicular osteolysis. CONTRAINDICATIONS General contraindications (infection, local tumor, coagulation disorders), higher grade instability of the AC joint (resection only together with stabilization). SURGICAL TECHNIQUE Diagnostic glenohumeral arthroscopy. Treatment of accompanying lesions (subacromial impingement, rotator cuff, long head of biceps). Subacromial arthroscopy with bursectomy (partial) and visualization of the AC joint. Resection of caudal osteophytes. Localization of the anterior portal using a spinal needle in the outside-in technique. Resection of 2-3 mm of the acromial side and the 3-4 mm of the clavicular side with shaver/acromionizer. RESULTS An isolated open AC joint resection was performed in 9 studies and an arthroscopic resection in 6 studies. Good and very good results were obtained in 79% (range 54-100%) in open resection and 91% (range 85-100%) in arthroscopic resections. Patients were able to return to activities of daily life more quickly after arthroscopic resections than after open surgery.

Two-stage revision of implant-associated infections after total hip and knee arthroplasty

Septic loosening of total hip and knee endoprostheses gains an increasing proportion of revision arthroplasties. Operative revisions of infected endoprostheses are mentally and physically wearing for the patient, challenging for the surgeon and a significant economic burden for healthcare systems. In cases of early infection within the first three weeks after implantation a one-stage revision with leaving the implant in place is widely accepted. The recommendations for the management of late infections vary by far. One-stage revisions as well as two-stage or multiple revision schedules have been reported to be successful in over 90% of all cases for certain patient collectives. But implant associated infection still remains a severe complication. Moreover, the management of late endoprosthetic infection requires specific logistics, sufficient and standardized treatment protocol, qualified manpower as well as an efficient quality management. With regard to the literature and experience of specialized orthopaedic surgeons from several university and regional hospitals we modified a commonly used treatment protocol for two-stage revision of infected total hip and knee endoprostheses. In addition to the achievement of maximum survival rate of the revision implants an optimisation of the functional outcome of the affected artificial joint is aimed for.

Muskuloskelettale Modellierung des patellofemoralen Gelenks

ZusammenfassungNumerische Simulationen leisten einen erheblichen Beitrag zum Verständnis von Erkrankungen des patellofemoralen Gelenks. Während experimentelle Arbeiten Limitationen hinsichtlich der Reproduzierbarkeit von Ergebnissen haben, können auf Modellbasis die Auswirkungen verschiedener operativer Verfahren systematisch evaluiert werden. Ziel dieser Arbeit war es, ein muskuloskelettales Modell vorzustellen, das in der Lage ist, die dynamischen Wechselwirkungen im patellofemoralen Gelenk wiederzugeben. Das Modell beinhaltet relevante Knochen- und Weichteilstrukturen des rechten Beins, darunter auch das mediale patellofemorale Ligament (MPFL). Ausgehend von diesem Modell wurden beispielhaft die Auswirkungen von 2 operativen Eingriffen bei aktiver Flexionsbewegung im Kniegelenk verdeutlicht: Zum einen der Einfluss verschiedener femoraler Ansatzpunkte bei der MPFL-Rekonstruktion auf die Belastung des medialen Bandes und zum anderen die Unterschiede in der Patellakinematik zwischen natürlichen und endoprothetisch versorgten Kniegelenken. Abschließend werden Möglichkeiten der muskuloskelettalen Modellierung dargelegt.AbstractNumerical simulations contribute to the understanding of patellofemoral diseases. Whereas cadaveric studies are limited with respect to reproducibility of results, the impact of different operative approaches can be systematically evaluated based on mathematical models. The objective of this study was to introduce a musculoskeletal model which is capable of describing the dynamic interactions within the patellofemoral joint. It contains major bony and soft tissue structures of the right leg including the medial patellofemoral ligament (MPFL). Two operative approaches were considered based on the model to illustrate the effect on patellofemoral biomechanics during active knee flexion: On the one hand the effect of femoral insertion during MPFL reconstruction on medial soft tissue tension, and on the other hand the difference in patella kinematics before and after total knee arthroplasty. Finally, the potential of musculoskeletal models is discussed.Numerical simulations contribute to the understanding of patellofemoral diseases. Whereas cadaveric studies are limited with respect to reproducibility of results, the impact of different operative approaches can be systematically evaluated based on mathematical models. The objective of this study was to introduce a musculoskeletal model which is capable of describing the dynamic interactions within the patellofemoral joint. It contains major bony and soft tissue structures of the right leg including the medial patellofemoral ligament (MPFL). Two operative approaches were considered based on the model to illustrate the effect on patellofemoral biomechanics during active knee flexion: On the one hand the effect of femoral insertion during MPFL reconstruction on medial soft tissue tension, and on the other hand the difference in patella kinematics before and after total knee arthroplasty. Finally, the potential of musculoskeletal models is discussed.

Musculoskeletal modeling of the patellofemoral joint. Dynamic analysis of patellar tracking

ZusammenfassungNumerische Simulationen leisten einen erheblichen Beitrag zum Verständnis von Erkrankungen des patellofemoralen Gelenks. Während experimentelle Arbeiten Limitationen hinsichtlich der Reproduzierbarkeit von Ergebnissen haben, können auf Modellbasis die Auswirkungen verschiedener operativer Verfahren systematisch evaluiert werden. Ziel dieser Arbeit war es, ein muskuloskelettales Modell vorzustellen, das in der Lage ist, die dynamischen Wechselwirkungen im patellofemoralen Gelenk wiederzugeben. Das Modell beinhaltet relevante Knochen- und Weichteilstrukturen des rechten Beins, darunter auch das mediale patellofemorale Ligament (MPFL). Ausgehend von diesem Modell wurden beispielhaft die Auswirkungen von 2 operativen Eingriffen bei aktiver Flexionsbewegung im Kniegelenk verdeutlicht: Zum einen der Einfluss verschiedener femoraler Ansatzpunkte bei der MPFL-Rekonstruktion auf die Belastung des medialen Bandes und zum anderen die Unterschiede in der Patellakinematik zwischen natürlichen und endoprothetisch versorgten Kniegelenken. Abschließend werden Möglichkeiten der muskuloskelettalen Modellierung dargelegt.AbstractNumerical simulations contribute to the understanding of patellofemoral diseases. Whereas cadaveric studies are limited with respect to reproducibility of results, the impact of different operative approaches can be systematically evaluated based on mathematical models. The objective of this study was to introduce a musculoskeletal model which is capable of describing the dynamic interactions within the patellofemoral joint. It contains major bony and soft tissue structures of the right leg including the medial patellofemoral ligament (MPFL). Two operative approaches were considered based on the model to illustrate the effect on patellofemoral biomechanics during active knee flexion: On the one hand the effect of femoral insertion during MPFL reconstruction on medial soft tissue tension, and on the other hand the difference in patella kinematics before and after total knee arthroplasty. Finally, the potential of musculoskeletal models is discussed.Numerical simulations contribute to the understanding of patellofemoral diseases. Whereas cadaveric studies are limited with respect to reproducibility of results, the impact of different operative approaches can be systematically evaluated based on mathematical models. The objective of this study was to introduce a musculoskeletal model which is capable of describing the dynamic interactions within the patellofemoral joint. It contains major bony and soft tissue structures of the right leg including the medial patellofemoral ligament (MPFL). Two operative approaches were considered based on the model to illustrate the effect on patellofemoral biomechanics during active knee flexion: On the one hand the effect of femoral insertion during MPFL reconstruction on medial soft tissue tension, and on the other hand the difference in patella kinematics before and after total knee arthroplasty. Finally, the potential of musculoskeletal models is discussed.

Titanium-copper-nitride coated spacers for two-stage revision of infected total hip endoprostheses.

Within the first two years after total hip arthroplasty implant-associated infection has become the second most common reason for a revision surgery. Two-stage implant exchange is frequently conducted using temporary spacers made of antibiotic-loaded cement in order to prevent a bacterial colonization on the spacer. Avoiding several disadvantages of cement spacers, a conventional hemi-endoprosthesis was equipped with a copper-containing implant coating for inhibition of bacterial biofilms. In the present paper details of this novel treatment concept are presented including a case report.

Einfluss des sich in Weiterbildung befindlichen Operateurs auf die postoperative Ergebnisqualität nach hüftendoprothetischer Versorgung in einem EndoProthetikZentrum der Maximalversorgung

BACKGROUND The study aims to evaluate whether the postoperative outcome and the probability of complications of patients with total hip arthroplasty increases significantly when surgeons in training are in charge, assisted by a high volume surgeon, compared to a highly experienced orthopaedic surgeon, within the context of a high volume hospital certified to EndoCert. MATERIAL AND METHODS 192 patients with a primary hip arthroplasty were included. To assess the outcome, the Harris Hip Score, WOMAC, SF-36 and EuroQol-5D were surveyed pre- and 12 months postoperatively. As complications we considered the quality indicators defined by EndoCert. RESULTS We found significant improvements in the postoperative score values with the qualifications of the surgeon in charge, even when a high volume surgeon or a surgeon in training was responsible. If a surgeon in training is assisted by a highly experienced surgeon, the risk of complications does not increase, although the operating time was significantly increased. CONCLUSION Both the surgeon in training as well as the arthroplasty patient benefit from implementing the EndoCert system, because the postoperative outcome and the complication probability is independent of the qualifcation of the operating orthopaedic surgeon performing total hip arthroplasty when assisted by an experienced surgeon.

Arthroskopische Resektion des AkromioklavikulargelenksArthroscopic resection of the acromioclavicular joint

OBJECTIVE Arthroscopic resection of the painful and degenerative altered acromioclavicular (AC) joint without destabilization of the joint and therefore pain relief and improvement in function. INDICATIONS Conservative failed therapy of painful AC joint osteoarthritis. Impingement caused by caudal AC joint osteophytes. Lateral clavicular osteolysis. CONTRAINDICATIONS General contraindications (infection, local tumor, coagulation disorders), higher grade instability of the AC joint (resection only together with stabilization). SURGICAL TECHNIQUE Diagnostic glenohumeral arthroscopy. Treatment of accompanying lesions (subacromial impingement, rotator cuff, long head of biceps). Subacromial arthroscopy with bursectomy (partial) and visualization of the AC joint. Resection of caudal osteophytes. Localization of the anterior portal using a spinal needle in the outside-in technique. Resection of 2-3 mm of the acromial side and the 3-4 mm of the clavicular side with shaver/acromionizer. RESULTS An isolated open AC joint resection was performed in 9 studies and an arthroscopic resection in 6 studies. Good and very good results were obtained in 79% (range 54-100%) in open resection and 91% (range 85-100%) in arthroscopic resections. Patients were able to return to activities of daily life more quickly after arthroscopic resections than after open surgery.