Witzleb Wc

Exposure to chromium, cobalt and molybdenum from metal-on-metal total hip replacement and hip resurfacing arthroplasty.

Background All metal implants—and metal-on-metal bearings in particular—corrode and cause a release of metal ions. Because cobalt and chromium have been shown to be carcinogenic and mutagenic in human and animal models, systemic toxicity and cancer risk are considered to be possible disadvantages of the metal-on-metal articulation. This study was designed to investigate the serum concentration profiles of chromium, cobalt and molybdenum after implantation of a Birmingham hip resurfacing arthroplasty (BHR) and a cementless total hip replacement with a 28-mm Metasul articulation (MTHR), over the first 2 years after implantation. Methods We analyzed profiles of metal ion serum levels in 111 patients implanted with a BHR, in 74 patients implanted with an MTHR, and in 130 implant-free probands control subjects using atomic absorption spectrophotometry. Results Chromium and cobalt concentrations (in μg/L) of all BHR and MTHR patients differed significantly from those of control subjects (chromium: < 0.25; cobalt: 0.25). The median chromium and cobalt concentrations in BHR patients had increased to 5.1 and 4.3 μg/ L 2 years after surgery. Concentrations in BHR patient exceeded those in the unilateral MTHR patients. Molybdenum serum concentrations hardly changed over time in either group and were not significantly different from the concentrations seen in the control subjects. Interpretation During the first 2 years after surgery, the Birmingham hip resurfacing arthroplasty leads to a significantly greater increase in serum chromium and cobalt levels than the 28-mm metal-on-metal MTHR. Observation of patients over a longer period will be necessary in order to evaluate any chronic adverse effects to the system due to elevated chromium and cobalt serum concentrations.

Serum metal ion exposure after total knee arthroplasty.

All metal implants release metal ions because of corrosion. This has been studied and debated, especially in metal-on-metal total hip arthroplasties. Total knee arthroplasty implants have large metal surface areas and therefore substantial potential for corrosion. We determined changes in serum levels of metal ions in 41 patients after cemented unconstrained total knee arthroplasty without patellar resurfacing, 18 with unilateral total knee arthroplasty (median, 66 months after surgery) and 23 patients with bilateral total knee arthroplasties (75 and 50 months after first and second surgeries, respectively). Serum concentrations of chromium, cobalt, and molybdenum were analyzed and related to the number of total knee arthroplasties and compared with those of 130 control patients without implants. The median chromium, cobalt, and molybdenum concentrations were 0.92, 3.28, and 2.55 μg/L, respectively, in the unilateral total knee arthroplasty sample and 0.98, 4.28, and 2.40 μg/L, respectively, in the bilateral total knee arthroplasty sample. We observed no difference between the serum levels in patients with unilateral and bilateral arthroplasties, but the serum levels of chromium and cobalt of both study groups were greater than those of the control group (less than 0.25 μg/L). The patients who had total knee arthroplasty had molybdenum profiles that were similar to those of the control group (median, 2.11 μg/L).

Neo-capsule tissue reactions in metal-on-metal hip arthroplasty

Background Modern-generation metal-on-metal articulations have a high wear resistance and may therefore be able to improve the long-term performance of artificial joints. However, the biological effects are still under debate. This study was undertaken to review the histopathological changes in neo-capsule tissues of different metal-on-metal hip arthroplasties. Methods Neo-capsule tissue samples from 46 hips with modern second-generation metal-on-metal articulations (39 hip resurfacings and 7 non-cemented total hip replacements) with a variety of failure mechanisms were examined histopathologically and immunohistochemically. Results A distinct lymphocytic infiltration was found in all cases with in situ times of more than 7 months, consisting of CD20-positive B-lymphocytes and CD3positive T-lymphocytes and sometimes thinly distributed CD138-positive plasma cells without dominant T-cell or plasma cell infiltrates. Interpretation This distinct lymphocytic infiltration has not been reported in tissue analyses of metal- or ceramic-on-polyethylene hip replacements, and may therefore be considered to be a characteristic histological pattern of tissue reactions on metal particles and/or ions around metal-on-metal bearings.

In vivo wear rate of the Birmingham Hip Resurfacing arthroplasty. A review of 10 retrieved components.

The wear of 8 femoral and 2 acetabular components of the Birmingham Hip Resurfacing (Midland Medical Technologies Ltd, Birmingham, UK) was measured using a coordinate measuring machine (CMM5; SIP, Geneva, Switzerland). After a median in situ time of 13 months, measurements of the Birmingham Hip Resurfacing femoral heads revealed a median volumetric wear of 2.9 mm(3). In one case with a cup abduction angle of 70 degrees , a significantly higher wear of 17.8 mm(3) was found. The 2 acetabular components showed volumetric wear of 5.4 and 27.6 mm(3) after 14 and 15 months in vivo. The wear rates of the investigated femoral components were somewhat, but not significantly, higher than the previously investigated 28-mm Metasul heads (median, 0.8 mm(3); Zimmer GmbH, Winterthur, Switzerland).

Short-term outcome after posterior versus lateral surgical approach for total hip arthroplasty - a randomized clinical trial*

PurposeCurrently, total hip replacement (THR) is most commonly performed via a posterior or a direct lateral approach, but the impact of the latter on the inventions outcome has yet not been quantified.MethodsWe compared the short-term outcome of cementless THR using the both approaches in a prospective, randomized controlled trial. 60 patients with unilateral osteoarthritis were included. Outcome assessment was performed one day before surgery and one week, four weeks, six weeks and 12 weeks after surgery, respectively, using the Harris Hip score as primary objective.ResultsWe found no significant difference in the intraindividual Harris Hip Score improvement at the pre-and three months post-operative assessments between both treatment groups (p = 0.115). However, Harris Hip scores and most functional and psychometric secondary endpoints showed a consistent tendency of a slightly better three months result in patients implanted via the posterior approach. In contrast a significant shorter operating time of the direct lateral approach was recorded (67 minutes versus 76 minutes, p < 0.001).ConclusionIn our opinion this slightly better short-term functional outcome after posterior approach is not clinical relevant. However, to make definitive conclusions all clinical relevant factors (i.e. mid- to long-term function, satisfaction, complication rates and long-term survival) have to be taken into account. Level of evidence: I - therapeutic

Clinical pathways. A useful steering instrument or a limitation for medical treatment

ZusammenfassungKlinische Pfade können medizinische Behandlungen aus der Prozessperspektive organisieren. Die traditionellen Abteilungsgrenzen werden dabei überschritten und die Behandlung des Patienten in den Mittelpunkt gestellt. Die Pfaderstellung erfordert einen mehrschrittigen und arbeitsaufwendigen Prozess unter Einbeziehung aller beteiligten Berufsgruppen. Die Nutzung von klinischen Pfaden in den Bereichen Patienteninformation, Ablauftransparenz sowie zur kontinuierlichen Qualitätssicherung bietet sich an. Die Steuerung von medizinischen und administrativen Prozessen wird durch die Analyse der Daten eines klinischen Pfades unterstützt und sichert damit die ärztliche Handlungsfreiheit.AbstractClinical pathways can be used to organize the optimal sequence for medical procedures. This process is patient centered and developed through the collaborative work of the participating medical specialties. The goals of clinical pathways are facilitation of outcomes, reduction of variance in patient care and cost containment. Clinical pathways can be used for patient information, internal and external transparency and in total quality management. The management of medical organisations can be supported by introducing the data from clinical pathways into prospective clinical and financial control.

Revision surgery of hip resurfacing

Early results of contemporary hip resurfacing are encouraging and consequently an increasing number of this procedure has been performed worldwide. A theoretical advantage of hip resurfacing is that failed components can be revised safely and successfully revised to a conventional total hip arthroplasty. As the number of systematically analyzed failures is still limited, however, current data from the literature cannot substantially support this assumption. Our personal results indicate that the conversion of a failed femoral cup (i.e., due to neck fracture or aseptic loosening) to a conventional stem is a relatively simple and safe procedure. If and how potential wear of a firmly integrated acetabular component might have any impact on this type of revision, warrants further investigations. The conversion of acetabular components is influenced by the quality of the remaining pelvic bone stock and can therefore be compared to conventional revision surgery. However, as most providers of hip resurfacings systems only offer one-piece acetabular shells, the possibility of an isolated modular insert exchange is rare. In conclusion, the argument of easy revision surgery after hip resurfacing should be used with care.

Revisionschirurgie des Oberflächenersatzes

Early results of contemporary hip resurfacing are encouraging and consequently an increasing number of this procedure has been performed worldwide. A theoretical advantage of hip resurfacing is that failed components can be revised safely and successfully revised to a conventional total hip arthroplasty. As the number of systematically analyzed failures is still limited, however, current data from the literature cannot substantially support this assumption. Our personal results indicate that the conversion of a failed femoral cup (i.e., due to neck fracture or aseptic loosening) to a conventional stem is a relatively simple and safe procedure. If and how potential wear of a firmly integrated acetabular component might have any impact on this type of revision, warrants further investigations. The conversion of acetabular components is influenced by the quality of the remaining pelvic bone stock and can therefore be compared to conventional revision surgery. However, as most providers of hip resurfacings systems only offer one-piece acetabular shells, the possibility of an isolated modular insert exchange is rare. In conclusion, the argument of easy revision surgery after hip resurfacing should be used with care.

Oberflächenersatz am Hüftgelenk

Currently, an increase in resurfacing arthroplasty in the treatment of hip osteoarthritis--especially in young adults--can be observed. New bearing technologies (mainly metal-on-metal surfaces) show better tribologic results than historical designs (e.g. the Wagner cup). At present, it is unclear whether these modifications and a definitively low dislocation rate--due to the large head diameter--can be supported by further good clinical results. The quantity as well as the quality of the available investigations prevents a definite opinion at the moment. Appropriate clinical studies with documented radiographic follow-up are necessary to compare the outcome of these new implants with standard techniques.

Resurfacing Arthroplasty of the Hip

Currently, an increase in resurfacing arthroplasty in the treatment of hip osteoarthritis--especially in young adults--can be observed. New bearing technologies (mainly metal-on-metal surfaces) show better tribologic results than historical designs (e.g. the Wagner cup). At present, it is unclear whether these modifications and a definitively low dislocation rate--due to the large head diameter--can be supported by further good clinical results. The quantity as well as the quality of the available investigations prevents a definite opinion at the moment. Appropriate clinical studies with documented radiographic follow-up are necessary to compare the outcome of these new implants with standard techniques.