H.C. Amstutz

Background of metal-on-metal resurfacing.

Abstract Hip resurfacing is not a new concept and attempts to treat hip arthritis without resecting the femoral head and neck have been made since the 1950s. The resurgence of new and better-engineered metal-on-metal bearings has provided the means to develop a viable prosthetic solution from a concept that was once abandoned. The lessons drawn from the early resurfacing era led to modern designs all using a cementless fixation of the acetabular component and a short metaphyseal stem designed for component alignment on the femoral side. Currently, only metallic devices can be manufactured with sufficient strength as a thin one-piece shell, combining excellent wear properties for large femoral heads and a bone-conserving device on the acetabular side. The early results of these new designs are extremely encouraging but the rapid development of the procedure needs to be controlled by appropriate training programmes to ensure its future success.

Positive cytokine production in failed metal-on-metal total hip replacements.

Tissues surrounding failed conventional total hips have been shown to produce inflammatory cytokines that can induce osteoclastic bone resorption. We evaluated the cytokine profiles of tissues from 5 failed metal-on-metal total hip replacements. Serial frozen sections were stained using immunohistochemical and in situ hybridization techniques. Inflammatory and osteoclast-stimulating cytokines were noted in the tissues. As compared to a group of 5 metal-polyethylene hip tissues, we found fewer CD68 positive macrophages, and lower levels of TGF- g and TNF- f , but no differences in CD3 positive lymphocytes, IL-1 g , IL-6 and PDGF- f in the metal-on-metal tissues. This may be due, in part, to the presence of wear particles from sources other than the bearing surfaces. Thus, cytokines associated with bone resorption and implant loosening may occur in total hips despite the use of alternative bearing materials.

EBRA-FCA for measurement of migration of the femoral component in surface arthroplasty of the hip

Studies on the migration of an implant may be the only way of monitoring the early performance of metal-on-metal prostheses. The Ein Bild Roentgen Analyse--femoral component analysis (EBRA-FCA) method was adapted to measure migration of the femoral component in a metal-on-metal surface arthroplasty of the hip using standard antero-posterior radiographs. In order to determine the accuracy and precision of this method a prosthesis was implanted into cadaver bones. Eleven series of radiographs were used to perform a zero-migration study. After adjustment of the femoral component to simulate migration of 3 mm the radiographs were repeated. All were measured independently by three different observers. The accuracy of the method was found to be +/- 1.6 mm for the x-direction and +/- 2 mm for the y-direction (95% percentile). The method was validated using 28 hips with a minimum follow-up of 3.5 years after arthroplasty. Seventeen were sound, but 11 had failed because of loosening of the femoral component. The normal (control) group had a different pattern of migration compared with that of the loose group. At 29.2 months, the control group showed a mean migration of 1.62 mm and 1.05 mm compared with 4.39 mm and 4.05 mm in the failed group, for the centre of the head and the tip of the stem, respectively (p = 0.001). In the failed group, the mean time to migration greater than 2 mm was earlier than the onset of clinical symptoms or radiological evidence of failure, 19.1 versus 32.2 months (p = 0.001) and 24.8 months (p = 0.012), respectively. EBRA-FCA is a reliable and valid tool for measuring migration of the femoral component after surface arthroplasty and can be used to predict early failure of the implant. It may be of value in determining the long-term performance of surface arthroplasty.

Hip resurfacing for osteonecrosis: two- to 18-year results of the Conserve Plus design and technique

AIMSnHip resurfacing arthroplasty (HRA) is an alternative to conventional total hip arthroplasty for patients with osteonecrosis (ON) of the femoral head. Our aim was to report the long-term outcome of HRA, which is not currently known.nnnPATIENTS AND METHODSnLong-term survivorship, clinical scores and radiographic results for 82 patients (99 hips) treated with HRA for ON over a period of 18 years were reviewed retrospectively. The mean age of the 67 men and 15 women at the time of surgery was 40.8 years (14 to 64). Patients were resurfaced regardless of the size of the osteonecrotic lesion.nnnRESULTSnThe mean clinical follow-up was 10.8 years (2 to 18). The mean University of California, Los Angeles hip scores at the last follow-up were 9.3, 9.4, 9.2 and 6.8 for pain, walking, function and activity, respectively. A total of six hips underwent revision surgery, four for loosening of the femoral component and two for loosening of the acetabular component. Using any revision as an end point, the 15-year Kaplan-Meier survivorship was 90.3%. There were no wear-related failures. There were no femoral failures among the hips reconstructed with a cemented metaphyseal stem. A total of five hips showed narrowing of the femoral neck; all stabilised and remain asymptomatic, 21 showed signs of femoral neck impingement.nnnCONCLUSIONnTo our knowledge, this is the first report of a series of HRA performed for ON with 15-year survivorship. Our data confirm that patients with advanced stages of ON of the femoral head are excellent candidates for HRA. Cite this article: Bone Joint J 2016;98-B:901-9.

Risk factors for wear-related failures after hip resurfacing in patients with a low contact patch to rim distance

Aims A contact patch to rim (CPR) distance of < 10 mm has been associated with edge‐loading and excessive wear. However, not all arthroplasties with a low CPR distance show problems with wear. Therefore, CPR distance may not be the only variable affecting the post‐operative metal ion concentrations. Patients and Methods We used multiple logistic regression to determine what variables differed between the patients who had high and low cobalt (CoS) and chromium (CrS) serum ion concentrations within a cohort of patients with low (< 10 mm) CPR distances. A total of 56 patients treated with unilateral hip resurfacing arthroplasty (HRA) had CoS and CrS ion studies performed more than one year after surgery. The mean age of the patients at the time of surgery was 51.7 years (29 to 70), with 38 women (68%) and 18 men (32%). Results It was seen that 47 patients had low ion levels (< 7&mgr;g/L) and nine had high ion levels (≥ 7&mgr;g/L). We found increased risks of high wear with decreasing CPR distance. Conclusion The use of CPR distance measurements to predict hips at risk for elevated wear is needed for all patients with HRA. We recommend that patients with low CPR distances have at least one serum ion study performed while patients with CPR distance > 10 mm do not need routine ion studies. We believe that patients with low CPR distance and low ions do not need repeat ion studies unless the patient becomes symptomatic or has substantial radiographic changes.

Hip Arthroplasty for Osteonecrosis of the Femoral Head

The typical patient affected by osteonecrosis (ON) of the hip joint ranges in age from 20 to 50 years [1], and men are usually more prone to idiopathic ON than women [2]. Also, bilateral involvement is quite frequent [3–5]. Acute discomfort is felt by the patient when necrotic bone no longer performs its support function and a subchondral fracture or collapse occurs [6]. Accurate staging of the disease is essential to select the appropriate treatment option, and many surgical procedures exist for the treatment of ON of the femoral head. A treatment algorithm can be defined, which will take into consideration (1) the age of the patient, (2) the development stage of the disease, and (3) the clinical and survivorship results of various procedures available to the treating physician. Here, we can see that this treatment algorithm is not set in stone as the evolution of surgical techniques can alter outcomes, possibly reducing the usefulness of a procedure while expanding the indications for another. Several staging systems exist [7–10] and some may be preferred in the description of the early stages of the disease, but we believe that the Ficat and Arlet classification provides the essential information to treat patients who may be best treated with one type of hip arthroplasty [7].

Der Metall-Metall-Hybridoberflächenersatz des Hüftgelenks@@@Metal-on-metal hybrid hip resurfacing: Entwicklung und aktueller Stand@@@Development and current state

Worldwide the employment of surface replacements using metal-on-metal components as an option, particularly for the young and active patient, has gained broad acceptance. Part of the attraction for hip resurfacing is its conservative nature as a prosthetic solution for hip arthritis. It is anatomical, replicating the normal hip and limb length, preserving proximal femoral bone, and is a truly minimally bone invasive approach with excellent outcome of joint function. The purpose of this article is to show the data of 1,000 Conserve(c) Plus hybrid metal-on-metal prostheses in a consecutive study of 1,140 patients with a follow-up of 5.6 years. The current Kaplan and Meier survival estimates of the prosthesis, using any conversion to total hip replacement as the end point, were 98.1% at 3 years [95% confidence interval (CI): 96.8-98.9%], 96.7% at 4 years (95% CI: 94.8-97.8%), and 95.2% at 5 years (95% CI: 93.0-96.8%). The mean postoperative Harris hip score was 93.3. The current state of metal-on-metal surface replacement is positive. The new generation of hip resurfacing has a lot of improvements. The purpose of this review of the procedure is to point out the definite improvements from earlier designs using polyethylene as well as to highlight the overall results and durability achieved by one surgeons extensive experience and to assess the results from other series and centers. We also want to point out the areas where further investigation is needed.ZusammenfassungDer Oberflächenersatz am Hüftgelenk gilt heute als weltweit akzeptiertes Verfahren zur knochenschonenden Versorgung von Patienten mit einer Koxarthrose. Durch diese Art der Prothese kann eine anatomische Rekonstruktion und sehr gute Funktion des Gelenks erreicht werden. Ziel des Artikels ist die Darstellung der ersten 1000xa0Fälle mit der Conserve©-Plus-Hybridoberflächenersatzprothese und die neuesten Entwicklungen auf dem Gebiet der Metall-Metall-Kappengleitpaarungen darzustellen. In einer konsekutiven Studie von 1140xa0Patienten wurden 1000 Hüftkappenprothesen einem Follow-up von durchschnittlich 5,6xa0Jahren unterzogen. Die Kaplan-Meier-Überlebensrate der implantierten Oberflächenersatzprothesen betrug 98,1% nach 3xa0Jahren [95%-Konfidenzintervall (-KI) =96,8–98,9%), 96,7% nach 4xa0Jahren (95%-KI=94,8–97,8%) und 95,2% nach 5xa0Jahren (95%-KI=93,0–96,8%) mit dem Endpunkt Konversion in eine reguläre Hüftgelenkprothese. Der Harris-Hip-Score (HHS) stieg postoperativ auf 93,3. Die neue Generation des Metall-Metall-Hybridoberflächenersatzes des Hüftgelenks bringt deutliche Verbesserungen im Vergleich zu Prothesen, die Polyethylenkomponenten verwendeten. Ein Vergleich mit anderen Serien und Gruppen und ein Ausblick auf zukünftige notwendige Untersuchungen im Bereich der Hüftgelenkkappenprothesen wird dargestellt.AbstractWorldwide the employment of surface replacements using metal-on-metal components as an option, particularly for the young and active patient, has gained broad acceptance. Part of the attraction for hip resurfacing is its conservative nature as a prosthetic solution for hip arthritis. It is anatomical, replicating the normal hip and limb length, preserving proximal femoral bone, and is a truly minimally bone invasive approach with excellent outcome of joint function. The purpose of this article is to show the data of 1,000 Conserve© Plus hybrid metal-on-metal prostheses in a consecutive study of 1,140 patients with a follow-up of 5.6xa0years. The current Kaplan and Meier survival estimates of the prosthesis, using any conversion to total hip replacement as the end point, were 98.1% at 3xa0years [95% confidence interval (CI): 96.8–98.9%], 96.7% at 4xa0years (95% CI: 94.8–97.8%), and 95.2% at 5xa0years (95% CI: 93.0–96.8%). The mean postoperative Harris hip score was 93.3. The current state of metal-on-metal surface replacement is positive. The new generation of hip resurfacing has a lot of improvements. The purpose of this review of the procedure is to point out the definite improvements from earlier designs using polyethylene as well as to highlight the overall results and durability achieved by one surgeon’s extensive experience and to assess the results from other series and centers. We also want to point out the areas where further investigation is needed.

Der Metall-Metall-Hybridoberflächenersatz des Hüftgelenks

Worldwide the employment of surface replacements using metal-on-metal components as an option, particularly for the young and active patient, has gained broad acceptance. Part of the attraction for hip resurfacing is its conservative nature as a prosthetic solution for hip arthritis. It is anatomical, replicating the normal hip and limb length, preserving proximal femoral bone, and is a truly minimally bone invasive approach with excellent outcome of joint function. The purpose of this article is to show the data of 1,000 Conserve(c) Plus hybrid metal-on-metal prostheses in a consecutive study of 1,140 patients with a follow-up of 5.6 years. The current Kaplan and Meier survival estimates of the prosthesis, using any conversion to total hip replacement as the end point, were 98.1% at 3 years [95% confidence interval (CI): 96.8-98.9%], 96.7% at 4 years (95% CI: 94.8-97.8%), and 95.2% at 5 years (95% CI: 93.0-96.8%). The mean postoperative Harris hip score was 93.3. The current state of metal-on-metal surface replacement is positive. The new generation of hip resurfacing has a lot of improvements. The purpose of this review of the procedure is to point out the definite improvements from earlier designs using polyethylene as well as to highlight the overall results and durability achieved by one surgeons extensive experience and to assess the results from other series and centers. We also want to point out the areas where further investigation is needed.ZusammenfassungDer Oberflächenersatz am Hüftgelenk gilt heute als weltweit akzeptiertes Verfahren zur knochenschonenden Versorgung von Patienten mit einer Koxarthrose. Durch diese Art der Prothese kann eine anatomische Rekonstruktion und sehr gute Funktion des Gelenks erreicht werden. Ziel des Artikels ist die Darstellung der ersten 1000xa0Fälle mit der Conserve©-Plus-Hybridoberflächenersatzprothese und die neuesten Entwicklungen auf dem Gebiet der Metall-Metall-Kappengleitpaarungen darzustellen. In einer konsekutiven Studie von 1140xa0Patienten wurden 1000 Hüftkappenprothesen einem Follow-up von durchschnittlich 5,6xa0Jahren unterzogen. Die Kaplan-Meier-Überlebensrate der implantierten Oberflächenersatzprothesen betrug 98,1% nach 3xa0Jahren [95%-Konfidenzintervall (-KI) =96,8–98,9%), 96,7% nach 4xa0Jahren (95%-KI=94,8–97,8%) und 95,2% nach 5xa0Jahren (95%-KI=93,0–96,8%) mit dem Endpunkt Konversion in eine reguläre Hüftgelenkprothese. Der Harris-Hip-Score (HHS) stieg postoperativ auf 93,3. Die neue Generation des Metall-Metall-Hybridoberflächenersatzes des Hüftgelenks bringt deutliche Verbesserungen im Vergleich zu Prothesen, die Polyethylenkomponenten verwendeten. Ein Vergleich mit anderen Serien und Gruppen und ein Ausblick auf zukünftige notwendige Untersuchungen im Bereich der Hüftgelenkkappenprothesen wird dargestellt.AbstractWorldwide the employment of surface replacements using metal-on-metal components as an option, particularly for the young and active patient, has gained broad acceptance. Part of the attraction for hip resurfacing is its conservative nature as a prosthetic solution for hip arthritis. It is anatomical, replicating the normal hip and limb length, preserving proximal femoral bone, and is a truly minimally bone invasive approach with excellent outcome of joint function. The purpose of this article is to show the data of 1,000 Conserve© Plus hybrid metal-on-metal prostheses in a consecutive study of 1,140 patients with a follow-up of 5.6xa0years. The current Kaplan and Meier survival estimates of the prosthesis, using any conversion to total hip replacement as the end point, were 98.1% at 3xa0years [95% confidence interval (CI): 96.8–98.9%], 96.7% at 4xa0years (95% CI: 94.8–97.8%), and 95.2% at 5xa0years (95% CI: 93.0–96.8%). The mean postoperative Harris hip score was 93.3. The current state of metal-on-metal surface replacement is positive. The new generation of hip resurfacing has a lot of improvements. The purpose of this review of the procedure is to point out the definite improvements from earlier designs using polyethylene as well as to highlight the overall results and durability achieved by one surgeon’s extensive experience and to assess the results from other series and centers. We also want to point out the areas where further investigation is needed.