Minimum ten-year results of a 28-mm metal-on-metal bearing in cementless total hip arthroplasty in patients fifty years of age and younger

An Atypical Adverse Local Tissue Reaction Seen With Metal-On-Metal Total Hip Arthroplasty Utilizing Polyethylene Liners With Metal Inlays

Adverse local tissue reaction (ALTR) is a frequently described, although uncommon, complication of metal-on-metal total hip arthroplasty. Here in we report on 2 patients with unique metal-inlay polyethylene liners who suffered from ALTR that required revision arthroplasty. In 2 of 3 cases the femoral trunnion was noted to have minimal corrosion and the stem was salvaged with a titanium adapter. In one case there was catastrophic femoral stem failure and an extended trochanteric osteotomy was required to remove the unique lateral flare stem. The surgeon must pay special attention when scrutinizing radiographs to identify a metal inlay polyethylene liner and when performing revision arthroplasty to prevent greater trochanter fracture in a patient who likely already has compromised abductor function due to ALTR.

Cementless metal-on-metal versus ceramic-on-polyethylene hip arthroplasty in under-50 year-olds with 20 to 22 years' follow-up: Was it a good idea to abandon the small-diameter metal-on-metal bearing?

In 2005 and 2011, we reported results for a comparative study of two types of 28-mm bearing (metal-on-metal (MoM) and ceramic-on-polyethylene (CoP) in active patients with respectively 5 and 12 years' follow-up. The present report is an update at a mean 20 years' follow-up, addressing 2 issues: (1) implant survival at a mean 20 years; and (2) long-term complications with the metal-on-metal bearing. Twenty-eight millimeters MoM bearings show good survival at 20 years in young active subjects. Two groups of cementless hip prostheses were compared: Metasul™ 28mm MoM versus 28mm CoP. The MoM group comprised 30 patients (39 hips), with a mean age of 40±6.7 years [range, 22.6-49 years], and the CoP group comprised 32 patients (39 hips), with a mean age of 40.5±8.7 years [range, 15-50 years]. The groups were matched in 2005 for age, activity level and preoperative Harris score. At a mean 20±5.3 years' follow-up [range, 5-23 years], in the MoM group 2 hips (5%) showed limited non-progressive acetabular osteolysis, not requiring revision surgery; in the CoP group, there were 21 revision procedures (54%), including 15 for polyethylene wear. In the MoM group, the median total blood cobalt concentration was 1.03g/L [range, 0.3-3.5] and the median chromium concentration was 1.07g/L [range, 0.3-3.2]. Twenty-year all-cause survival was 100% in the MoM group, and 46% (95% CI, 37-59%) in the CoP group (p<0.0001). At long-term follow-up, MoM implants showed better survival than CoP implants in a young active population. Level of evidence: III, matched case series.

Long-Term Outcome of Small Head Metal-On-Metal Total Hip Arthroplasty: A 15-to-22 Year Follow-Up

BACKGROUND

The Metasul articular interface was a second-generation metal-on-metal (MoM) total hip arthroplasty (THA) that was introduced as a promising interface with improved manufacturing technology, better clearances, and enhanced metal hardness. In December 2001, the manufacturer recalled these implants due to the failure of cup osseointegration.

METHODS

Between 1997 and 2004, 168 consecutive primary Metasul THAs were performed in 144 patients. Most patients received a cementless femoral and porous-coated acetabular component with 28 mm head. A competing risk analysis was performed for determination separately for bearing surface-related, recalled bearing failure, and end point revision for any reason. For clinical patient evaluation, we used Harris hip score and University of California at Los Angeles scores. Cobalt and chromium ion level measurement and standard radiographic assessment was performed.

RESULTS

Of the 168 THAs, 19 hips were revised at a mean period of 15 years as follows: 12 of them were due to recalled acetabular component, five hips had noninterface-related complication, and two true interface surface failure. The survival distribution function of all hips with revision for any reason was 88.4%, for bearing interface relation 98.8%, and 92.6% for recalled cups. The mean Harris hip score and University of California at Los Angeles scores were 85 and 6, respectively, and the median Co and Cr blood levels were 1.0 and 0.91 μg/L.

CONCLUSION

Excluding the recalled components, Metasul articular interface has performed extremely well at a minimum follow-up of 15 years in this relatively young population. There were two interface-related revisions in the entire cohort.

Minimum 15-year results of metasul 28-mm metal-on-metal total hip arthroplasty in patients younger than 50 years of age

Background

Some propitious mid- and long-term studies had been reported for MoM bearings; however, most studies have addressed specific patient groups rather than younger, active patients, who probably represent the most suitable population for investigations on wear and osteolysis. The purpose of this study to evaluate the long-term results of second-generation metal-on-metal cementless total hip arthroplasty (THA) in patients aged <50 years.

Methods

From December 1997 to January 2004, primary THA using a metal-on-metal bearing cementless implant was performed in 63 patients (72 hips) aged <50 years. The mean follow-up duration was 18.6 (range, 15.9–22.1) years, and the mean age at initial operation was 39 (range, 22–49) years. Clinical results, complications, survivorship, osteolysis, and aseptic loosening were evaluated.

Results

The mean Harris hip score and Western Ontario and McMaster Universities Arthritis Index scores were improved from 57.8 (range, 28–69) points and 73.4 (range, 63–94) points preoperatively to 91.7 (range, 80–100) points and 25.5 points (range, 17–38) points, respectively, at the last follow-up. Osteolysis lesions were found in 12 hips (acetabulum, 6 and femur, 6). The notching occurred on the femoral stem neck occurred in 12 hips. The mean serum cobalt and chromium concentrations were 2.3 (range, 0.2–10.6) μg/L and 1.7 (range, 0.4–8.1) μg/L, respectively, at a mean follow-up of 12.7 years in 32 patients (50.1%). The Kaplan-Meier survivorship curve analysis with revision for any reason as the endpoint revealed that 93.1% survived at 18.6 years’ follow-up.

Conclusions

Second-generation metal-on-metal cementless THA was found to produce satisfactory clinical and radiographic results with a low revision rate for osteolysis and aseptic loosening in patients aged less than 50 years.

Survival at 11 to 21 years for 779 Metasul® metal-on-metal total hip arthroplasties

BACKGROUND

Total hip arthroplasties (THAs) bearing is one of the most important factors for hip replacement because THA survival depends on it. Metal-on-metal (MoM) bearing has lower wear than metal-on-polyethylene but lot of aseptic loosening decrease utilization. We analyze the survival rate of 28 mm Metasul® bearings after a mean follow-up of 12.9 years.

METHODS

The main objective of this study was to evaluate the survival of the MoM. We evaluate 779 consecutive THAs performed between January 1995 and December 2005 for primary osteoarthritis, congenital dysplasia classified Crowe I, or rheumatoid arthritis. Survival rate was calculated by the Kaplan-Meir method. The association between survival and age, gender, body mass index (BMI), and surface coating was investigated with a proportional odds model. The clinical assessment included Oxford score.

RESULTS

Six hundred fifty-two THAs were reviewed. Sixty-two revisions (9.5%) were performed including 34 aseptic loosening and 11 deep infections. The survival for prosthesis with any reason at 20 years was 87% (confidence interval (CI) 83-90.2) for aseptic loosening at 20 years was 90.1% (CI 87-93.8). There was no association with age, BMI, and surface coating. Gender was significant with lower aseptic loosening for men, hazard ratio = 0.45, p value = 0.035. Oxford score was 57 ± 6.7 (19-60).

CONCLUSION

The survival rate of Metasul was well and seems to be like our clinical finding. However, radiographic aseptic loosening without surgery is not included in the survival rate. The Oxford score was very good with a lot of patients with asymptomatic hip.

LEVEL OF EVIDENCE

Level IV/Retrospective study.

Metasul vs Cerasul bearings: a prospective, randomized study at a mean eighteen years

BACKGROUND

The aims of our study were to compare the clinical, radiographic outcomes and survivals between second-generation metal-on-metal (Metasul) and ceramic-on-ceramic (Cerasul) bearings at a very long-term follow-up.

METHODS

A prospective, randomized study was originally performed on a consecutive series of 250 cementless, 28-mm head and primary total hip arthroplasties between 1999 and 2002. For each bearing (Metasul or Cerasul), 125 THAs were initially included. All cases were evaluated both clinically and radiographically, and survival was assessed, considering revisions for aseptic loosening or for any reason as the end points for failure.

RESULTS

At a mean 18-year follow-up, clinical and radiographic outcomes were similar. Harris Hip Score increased 30% in the Metasul group and 32% in the Cerasul group (p = 0.6). Survival free of aseptic loosening was higher for Cerasul (100%), than for Metasul (94% [CI 88-99.9]) (p = 0.04). Survival free of any revision was 91% ([CI 84-98%]) for Cerasul and 91% ([CI 84-98%]) for Metasul. Fractures of Cerasul insert occurred in four cases (3%) at a mean 12.5 ± 3.3 years (range, 6 to 17 years).

CONCLUSION

At 18 years, Cerasul demonstrated higher survivorship than Metasul considering aseptic loosening as an end point. However, Cerasul liners had high rate of fracture because of its sandwich design (thin ceramic liner into polyethylene). These implants are no more available on the market.

The Migration Pattern of a Cementless Hydroxyapatite-Coated Titanium Stem under Immediate Full Weight-Bearing-A Randomized Controlled Trial Using Model-Based RSA

(1) Background: High primary stability is important for the long-term survival of cementless femoral stems in total hip arthroplasty (THA). The objective of this study was to investigate the migration pattern of a hydroxyapatite-coated cementless hip stem developed for minimally invasive surgery using model-based radiostereometric analysis (RSA). (2) Methods: In this randomized controlled trial, 44 patients with an indication for cementless primary THA were randomly allocated to receive either the SL-PLUS MIA stem, developed for minimally invasive surgery, or the SL-PLUS stem (Smith & Nephew Orthopaedics, Baar, Switzerland) which served as a control group. Unlimited weight-bearing was permitted postoperatively in both groups. Model-based RSA was performed after six weeks and after 3, 6, 12 and 24 months postoperatively. (3) Results: Mean total stem subsidence at two-year follow-up was 0.40 mm (SD 0.66 mm) in the SL-PLUS group and 1.08 mm (SD 0.93 mm) in the SL-PLUS MIA group (p = 0.030). Stem subsidence occurred during the first six weeks after surgery, indicating initial settling of the stem under full weight-bearing. Both stem designs showed good osseointegration and high secondary stability with no further migration after initial settling. (4) Conclusions: Settling of a cementless straight femoral stem occurs during the first six weeks after surgery under full weight-bearing. Although initial stem migration was higher in the SL-PLUS MIA group, it had no influence on secondary stability. All implants showed good osseointegration and high secondary stability with no signs of implant loosening during this two-year follow-up period.

Serum cobalt concentrations remain at low levels at a minimum of 20 years following metal-on-metal total hip arthroplasty

Aims

Second-generation metal-on-metal (MoM) articulations in total hip arthroplasty (THA) were introduced in order to reduce wear-related complications. The current study reports on the serum cobalt levels and the clinical outcome at a minimum of 20 years following THA with a MoM (Metasul) or a ceramic-on-polyethylene (CoP) bearing.

Methods

The present study provides an update of a previously published prospective randomized controlled study, evaluating the serum cobalt levels of a consecutive cohort of 100 patients following THA with a MoM or a CoP articulation. A total of 31 patients were available for clinical and radiological follow-up examination. After exclusion of 11 patients because of other cobalt-containing implants, 20 patients (MoM (n = 11); CoP (n = 9)) with a mean age of 69 years (42 to 97) were analyzed. Serum cobalt levels were compared to serum cobalt levels five years out of surgery.

Results

The median cobalt concentration in the MoM group was 1.04 μg/l (interquartile range (IQR) 0.64 to 1.70) at a mean of 21 years (20 to 24) postoperatively and these values were similar (p = 0.799) to cobalt levels at five years. In the CoP control group, the median cobalt levels were below the detection limit (< 0.3 μg/l; median 0.15 μg/l, IQR 0.15 to 0.75) at 20 years. The mean Harris Hip Score was 91.4 points (61 to 100) in the MoM group and 92.8 points (63 to 100) in the CoP group.

Conclusion

This study represents the longest follow-up series evaluating the serum cobalt levels after 28 mm head MoM bearing THA and shows that serum cobalt concentrations remain at low levels at a mean of 21 years (20 to 24) after implantation.

Cite this article:Bone Joint Res. 2020;9(3):145–150.

Long-Term Results of a Second-Generation, Small-Diameter, Metal-On-Metal Bearing in Primary Total Hip Arthroplasty at 14-year Follow-Up

(1) Background: The objective of the present study was to review the clinical and radiological results of a small-head, MoM bearing in primary THA and to determine blood metal ion levels at long-term follow-up. (2) Methods: We retrospectively evaluated the clinical and radiological results of 284 small-diameter, MoM 28-mm Metasul THA at a mean follow-up of 14.5 years, and measured blood metal ion concentrations in 174 of these patients. (3) Results: After 14 years, survival free for revision due to any reason was 94%. Proximal femoral osteolysis was seen in 23% of hips, and MRI demonstrated ARMD in 27 of the 66 investigated hips (41%). Mean cobalt, chromium, and titanium ion concentrations were 0.82 µg/L (range 0.22-4.45), 1.51 µg/L (0.04-22.69), and 2.68 µg/L (0.26-19.56) in patients with unilateral THA, and 2.59 µg/L (0.43-24.75), 2.50 µg/L (0.26-16.75), and 3.76 µg/L (0.67-19.77), respectively in patients with bilateral THA. Twenty-nine percent of patients showed cobalt or chromium ion levels > 2 µg/L. (4) Conclusions: Despite good clinical long-term results, increased blood metal ion levels (cobalt or chromium > 2 µg/L) were found in approximately one-third of asymptomatic patients, and proximal femoral osteolysis and ARMD were frequently seen in this cohort. Blood metal ion analysis appears helpful in the long-term follow-up of these patients in order to identify individuals at risk. In accordance with contemporary consensus statements, symptomatic patients with elevated metal ion levels and/or progressive osteolysis should be considered for additional CT or MARS MRI to determine the extent of soft tissue affection prior to revision surgery. Further studies are necessary to investigate the clinical relevance of ARMD in asymptomatic patients with small-head, MoM THA.

Pseudotumours, cobalt and clinical outcome in small head metal-on-metal versus conventional metal-on-polyethylene total hip arthroplasty

BACKGROUND

Metal-on-metal total hip arthroplasty (MoM THA) is associated with the formation of pseudotumours. Studies mainly concern pseudotumour formation in large head MoM THA. We performed a long-term follow-up study, comparing pseudotumour incidence in small head metal-on-metal (SHMoM) THA with conventional metal-on-polyethylene (MoP) THA. Predisposing factors to pseudotumour formation were assessed.

METHODS

From a previous randomised controlled trial comparing SHMoM (28 mm) cemented THA with conventional MoP cemented THA, patients were screened using a standardised CT protocol for the presence of pseudotumours. Serum cobalt levels and functional outcome were assessed.

RESULTS

56 patients (33 MoP and 23 MoM) were recruited after mean follow-up of 13.4 years (SD 0.5). The incidence of pseudotumours was 1 (5%) in the SHMoM THA cohort and 3 (9%) in the MoP THA cohort. Prosthesis survival was 96% for both SHMoM and MoP THAs. Serum cobalt levels did not exceed acceptable clinical values (<5 µg/L) whereas no differences in cobalt levels were detected at follow-up between both groups. Oxford and Harris Hip Scores were good and did not differ between SHMoM and MoP THA.

CONCLUSIONS

This long-term follow-up study shows a low incidence of pseudotumour formation and good functional outcome in cemented head-taper matched SHMoM and MoP THA.

Long-term survival of hybrid total hip arthroplasty with the uncemented CLS cup, cemented Müller cobalt-chromium stem, and 28-mm Metasul™ bearings: Retrospective review of 115 hips after a minimum of 17.8 years

BACKGROUND

Hard-on-hard bearings require a meticulous implantation technique but may be associated with lower wear rates in young active patients. Among them, metal-on-metal (MoM) bearings have been blamed for specific complications including adverse reactions to metal debris and metal hypersensitivity. These complications have been chiefly reported with large-head MoM implants (except when used for hip resurfacing). Most of the published data on small-head MoM implants were obtained using uncemented stems. To our knowledge, no information on outcomes beyond 15 years is available for small-head MoM implants with cemented cobalt-nickel-chromium (Co-Ni-Cr) stems, which might increase the risk of complications. The objective of this study was to collect long-term follow-up data on patients who underwent hybrid total hip arthroplasty (THA) with 28-mm MoM Metasul™ bearings in order to assess: (1) long-term survival (based on the revision rate), (2) and the occurrence of adverse reactions to metal debris documented during revision.

HYPOTHESIS

Survival of 28-mm Metasul™ bearings used with hybrid THA is acceptable.

PATIENTS AND METHODS

A single-centre retrospective study was conducted in consecutive patients managed using 28-mm Metasul™ bearings in a press-fit cup, with a cemented Co-Ni-Cr stem. Follow-up was at least 17 years. The clinical and radiographic data were analysed. Mean age at surgery was 57.3±7.9 years (range, 29.6-75.3 years).

RESULTS

The study included 115 hips with a mean follow-up of 20.3±0.8 years (range, 17.8-21.6 years). Survival to revision for any reason was 86.10% (95% CI, 79.8-92.4%) and survival to revision for aseptic loosening was 92.6% (95% CI, 87.7-97.6). Half the specimens obtained during revision showed a macrophage reaction and a non-specific inflammatory infiltrate. No patient experienced complications specifically related to the use of Metasul™ bearings with a cemented Co-Ni-Cr stem.

DISCUSSION

Long-term survival of 28-mm MoM Metasu™ bearings was close to that of metal-on-polyethylene bearings and lower than that of ceramic-on-ceramic or small-head MoM bearings in other studies. No complications specifically related to the use of small-head MoM bearings with a cemented Co-Ni-Cr stem were recorded.

LEVEL OF EVIDENCE

IV, retrospective study.

A Minimum of 15-Year Results of Cementless Total Hip Arthroplasty Using a 28-mm Metal-On-Metal Articulation

BACKGROUND

We previously reported unexpected early failures of total hip arthroplasty (THA) utilizing a 28-mm Ultima metal-on-metal (MoM) articulation. However, long-term results of small-diameter MoM THAs still remain unclear. The purpose of this study was to evaluate the clinical and radiographic outcomes of the previously reported cohort at a minimum follow-up of 15 years.

METHODS

The original cohort consisted of 171 primary THAs (167 patients) using a 28-mm MoM articulation performed between April 2000 and March 2002. Of these, 130 hips (126 patients) were reviewed at an average follow-up of 17.1 (range, 15-18) years. Clinical score, complications, presence of osteolytic lesion, serum metal ion concentrations, and implant survivorships were evaluated.

RESULTS

The mean Harris Hip Score improved from 44.9 points preoperatively to 90.5 points at the latest follow-up. During the entire period since the original surgery, a total of 5 revisions (3.8%) were associated with adverse reaction to metal debris (ARMD). The last revision surgery for symptomatic ARMD was performed at 6 years postoperatively. The implant survivorships with an end point of revision for aseptic failure and for any reason were 95.4% and 93.8%, respectively. Radiographic osteolytic lesions were detected in 27 hips (20.8%). The average serum metal concentration was 2.50 (range, 0.12-9.86) μg/L for cobalt and 2.81 (range, 0.82-12.3) μg/L for chromium.

CONCLUSIONS

THA using a 28-mm MoM articulation showed favorable long-term outcomes with a relatively high revision-free survival rate. There was no significant symptomatic ARMD after the last acetabular revision performed at 6 years postoperatively.

Prevalence and natural course of pseudotumours after small-head metal-on-metal total hip arthroplasty: a minimum 18-year follow-up study of a previous report

AIMS

The present study investigated the five-year interval changes in pseudotumours and measured serum metal ions at long-term follow-up of a previous report of 28 mm diameter metal-on-metal (MoM) total hip arthroplasty (THA).

PATIENTS AND METHODS

A total of 72 patients (mean age 46.6 years (37 to 55); 43 men, 29 women; 91 hips) who underwent cementless primary MoM THA with a 28 mm modular head were included. The mean follow-up duration was 20.3 years (18 to 24). All patients had CT scans at a mean 15.1 years (13 to 19) after the index operation and subsequent follow-up at a mean of 20.2 years (18 to 24). Pseudotumour volume, type of mass, and new-onset pseudotumours were evaluated using CT scanning. Clinical outcomes were assessed by Harris Hip Score (HHS) and the presence of groin pain. Serum metal ion (cobalt (Co) and chromium (Cr)) levels were measured at the latest follow-up.

RESULTS

At final follow-up, pseudotumours were observed in 26/91 hips (28.6%). There was an increase in volume of the pseudotumour in four hips (15.4%), no change in volume in 21 hips (80.8%), and a decrease in volume in one hip (3.8%). There were no new-onset pseudotumours. There was no significant difference in HHS between patients with and without pseudotumours. At final follow-up, mean serum Co ion levels and median Co:Cr ratios were significantly greater in patients with pseudotumours, but the serum Cr ion levels were not significantly different.

CONCLUSION

At a mean 20 years of follow-up, pseudotumours were observed in 26/91 hips (28.6%) with no new-onset pseudotumours during subsequent follow-up. Most pseudotumours in small-head MoM THA were static in volume and asymptomatic with normal serum metal ion levels. Cite this article: Bone Joint J 2019;101-B:317-324.

Comparative Mid-term Follow-up Study of Primary Total Hip Arthroplasty with Metal-on-metal and Metal-on-polyethylene Bearings

OBJECTIVE

To compare mid-term clinical results of total hip arthroplasty (THA) with metal-on-metal (MoM) and metal-on-polyethylene (MoP) bearings and to evaluate the biological safety of the two kinds of prostheses.

METHODS

Thirty-two patients who received a primary THA with an MoM articulation between January 2008 and December 2010 were selected to form the MoM group retrospectively. The MoP group consisted of 32 patients who received a THA with an MoP prosthesis during the same period. Clinical assessments, imaging examinations, laboratory tests, and metal ion concentration detections were conducted on each patient. Another 32 healthy volunteers were recruited as the control group.

RESULTS

Twenty-seven patients in the MoM group and 28 patients in the MoP group completed the follow-up, with a mean follow-up time of 74.6 and 75.9 months, respectively. The mean Harris score at the latest follow-up was 91.5 ± 5.1 in the MoM group versus 88.9 ± 4.0 in the MoP group (P = 0.22). The MoM group showed a better range of motion in flexion, abduction, and external rotation. Co and Cr levels in the MoM group were 2.5-fold and 2.0-fold of these in the MoP group. A mild change of liver function was observed in both groups, while the values of renal function and humoral immunity stayed static. Elevated proportions of Th1 and Th17 cells and decreased proportion of Th2 cells were observed in the MoM group. The occurrence rate of pseudotumors in the MoM and MoP groups was 40.74% ± 9.45% and 14.28% ± 6.61%, respectively (P < 0.05).

CONCLUSION

At the mid-term follow-up, clinical results were satisfied in both groups. MoM prosthesis could result in elevated serum metal ion levels and there is a higher risk of pseudotumor. Long follow-up is needed to evaluate the safety of MoM prostheses.

Long-Term Outcomes After Metal-on-Metal Total Hip Arthroplasty With a 28-mm Head: A 17- to 23-Year Follow-Up Study of a Previous Report

BACKGROUND

Second-generation, metal-on-metal total hip arthroplasty (MoM THA) using a 28-mm head has shown favorable results compared with large head MoM THA. The purpose of this study is to evaluate the long-term outcomes of cementless primary MoM THA with a 28-mm head and the incidence of osteolysis using computed tomography.

METHODS

A total of 92 patients (53 men and 39 women) who underwent primary cementless MoM THA (114 hips) with a 28-mm head were enrolled in this study. Their mean age was 46.2 years at the time of surgery. The mean follow-up duration was 20 years. The Harris hip score, presence of thigh or groin pain, radiographic results, presence of peri-implant osteolysis, histologic analysis, and Kaplan-Meier survival curves were evaluated.

RESULTS

The mean preoperative Harris hip score of 50.5 improved to 85.1 at the final follow-up. Eight patients (8 hips) experienced groin pain, but none had thigh pain. Twelve revisions (6.2%) were performed including 10 hips for aseptic loosening with osteolysis and 2 hips for periprosthetic fracture around the stem. At 23 years, 91% of patients were free from revision of the acetabular component due to aseptic loosening and 90.1% were free from revision of both femoral and acetabular components due to any reason. Osteolysis was identified around the cup in 12 cases (10.5%) and around the stem in 7 cases (6.1%).

CONCLUSION

MoM THA with a 28-mm head showed a relatively low rate of aseptic implant loosening at a mean follow-up of 20 years.

What Is the Long-term Survival for Primary THA With Small-head Metal-on-metal Bearings?

BACKGROUND

Large-head metal-on-metal (MoM) bearing hip replacements have been shown to have a much higher rate of revision than other bearing surfaces. However, small-head (≤ 32 mm) MoM bearing surfaces have been in use for many years with several reports of satisfactory mid- to long-term survivorship. It is unclear whether the long-term survival of small-head MoM devices will continue to be satisfactory or whether the same concerns seen with the large-head MoM devices will ultimately become more prevalent.

QUESTIONS/PURPOSES

We analyzed a large national registry to ask: (1) What is the 15-year Kaplan-Meier survivorship of primary conventional THA using small-head (≤ 32 mm) MoM bearing surfaces compared with large-head MoM bearing surfaces in primary THA? (2) Is there an increased rate of revision for adverse reaction to metal debris (ARMD) in this group of patients over time?

METHODS

The Australian Orthopaedic Association National Joint Replacement Registry longitudinally maintains data on all primary and revision joint arthroplasties with nearly 100% capture. We analyzed all conventional primary THAs performed from Registry inception in September 1999 until December 31, 2015, in patients with a diagnosis of osteoarthritis and using MoM bearing surfaces ≤ 32 mm in diameter, defined as small-head MoM. The study group included 4838 primary THA with ≤ 32-mm MoM bearing surfaces. There were 2506 (51.8%) male patients and the median age of patients undergoing THA with a small-head MoM bearing surface was 64 years (range, 20-92 years of age). The outcome measure was the cumulative percent revision defined as the time to first revision using Kaplan-Meier estimates of survivorship at 15 years; reasons for revision and type of revision were also examined. We specifically investigated whether there was an increased risk of revision for ARMD in this MoM group compared with all other bearing surfaces. We compared these results with large-head MoM THAs (femoral head size > 32 mm).

RESULTS

The cumulative percent revision for small-head MoM designs at 15 years was 8.5% (95% confidence interval [CI], 7.3-9.9). The cumulative percent revision for large-head MoM at 14 years was 27.4% (95% CI, 24.8-30.2). Prostheses with a large-head MoM articulation have a higher rate of revision than small-head MoM bearing surfaces (hazard ratio after 6 years, 5.14; 95% CI, 4.1-6.5; p < 0.001). Over time, there was a gradual increase in the diagnosis of ARMD for small-head MoM and the cumulative incidence of revision for ARMD was 0.8% at 15 years.

CONCLUSIONS

Despite survival that is substantially greater than that of large-head MoM THAs, there has been a marked decrease in the use of small-head MoM designs in our registry. Although the reasons for this are likely multifactorial, the increasing incidence of revisions for ARMD among small-head MoM THAs is concerning.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Long-term clinical results of the Metasul metal-on-metal total hip arthroplasty: 12.6 years follow-up of 128 primary total hip replacements

INTRODUCTION

The purpose of the present study is to report the long-term clinical results of an uncemented total hip arthroplasty (THA) using a Metasul metal-on-metal (MoM) 28-mm bearing and to evaluate the long-term serum cobalt levels.

METHODS

At an average of 12.6 years following primary THA, we retrospectively reviewed the clinical results of the first 116 consecutive patients (128 THAs) in our institution who underwent 28-mm Metasul MoM THA. Of the 78 patients who were able to visit our outpatient clinic, serum cobalt levels were evaluated.

RESULTS

The overall survival rate of the cohort was 96.1% (95% confidence interval [CI], 93.2-99.6), 12.6 years (95% CI, 12.3-12.7 years) following surgery. 3 patients had undergone revision due to aseptic loosening of the stem and 2 patients sustained a periprosthetic fracture. The average modified Harris Hip Score was 90 (72-97) and the average Oxford Hip Score was 56 (48-60), representing both excellent outcome scores. The average serum cobalt of the entire cohort was 20.1 nmol/L (range 8.5-227.7 nmol/L). Serum cobalt levels of patients with a bilateral MoM THA were significantly higher (35.0 nmol/l, p<0.01). No relation between serum cobalt levels, subjective outcome, radiolucent lines on radiographs and survivorship of the implant was noted.

CONCLUSIONS

Long-term results of the metasul MoM bearing articulation in THA seem to be excellent, although cobalt serum levels should be monitored closely.

3rd generation ceramic-on-ceramic cementless total hip arthroplasty: a minimum 10-year follow-up study

INTRODUCTION

3^rd generation ceramic bearings were introduced in total hip arthroplasty (THA) with the potential to have better mechanical strength and wear properties than their predecessors. At present, there are few studies looking at the long-term results of this latest generation of ceramic bearings. The purpose of our study was to investigate the long-term clinical and radiographic results of 3^rd generation ceramic-on-ceramic THA and the incidence of ceramic specific complications such as squeaking and bearing surface fracture.

METHODS

The database of the senior author (J.D.W.) was reviewed. A total of 126 hip replacements performed in 108 patients (average age 39.6 years) with an average follow-up of 12.1 years (10-16 years) was identified. Clinical notes and plain radiographs were reviewed. To measure function, patients were contacted and an Oxford Hip Questionnaire was completed. Patients were also directly questioned about the presence of squeaking or any other sounds from the hip. Radiographs were evaluated for signs of wear, osteolysis, loosening and heterotopic ossification. The abduction angle of the acetabular component was measured.

RESULTS

The average Oxford Hip Score was 39.8 out of 48. Survivorship at 10 years was 94.6% (95% CI) with revision for any cause as the endpoint. There was 1 femoral head fracture, no osteolysis, no squeaking and no detectable wear.

CONCLUSIONS

The good clinical and radiographic results for this series of patients are similar to other recent long-term studies looking at 3^rd generation ceramic-on-ceramic THA. The results compare favourably with other bearing surfaces. The lack of osteolysis associated with this articulation is encouraging and may also make it a good choice for younger patients requiring total hip replacement.

Systematic review: lack of evidence for the success of revision arthroplasty outcome in younger patients

INTRODUCTION

Total hip arthroplasties (THAs) in younger patients are becoming increasingly popular. However, the outcome of subsequent revisions in younger patients is not well known and, therefore, their success (subsequent revision prosthesis survival) might be overestimated. We investigated available data on the outcome of primary- and subsequent revision THAs performed in the same cohort of patients who underwent primary THA under the age of 50.

METHODS

Medline, Embase and the Cochrane Library (CENTRAL) were searched up until April 13, 2016 for studies that reported both the survival of primary and subsequent revisions THA of single cohorts of patients younger than 50. Eligible articles had to include Kaplan Meier analysis or competing risk analysis for survival of the primary THA at a mean follow-up of 10 years, as well as for the subsequent revision THA within the same cohort.

RESULTS

We found 4,799 unique records; 43 of which were potentially eligible. Only 1 paper met our inclusion criteria. It reported on the survival of 69 primary prostheses at a mean of more than 10 years follow-up and 13 subsequent revisions.

CONCLUSIONS

There is a clear lack of evidence about the outcomes of the revision arthroplasty in younger patients. Only 1 study reported the survival-rate of subsequent revision arthroplasty with the minimum 10-year survival rate of the original THA cohort. In the future, this serious lack of knowledge could result in a large number of patients with no further reconstructive options after failed THA, and a large medical burden for society.

Comparison of metal ion concentrations and implant survival after total hip arthroplasty with metal-on-metal versus metal-on-polyethylene articulations

Background and purpose - Large metal-on-metal (MoM) articulations are associated with metal wear and corrosion, leading to increased metal ion concentrations and unacceptable revision rates. There are few comparative studies of 28-mm MoM articulations with conventional metal-on-polyethylene (MoP) couplings. We present a long-term follow-up of a randomized controlled trial comparing MoM versus MoP 28-mm articulations, focused on metal ions and implant survival. Patients and methods - 85 patients with a mean age of 65 years at surgery were randomized to a MoM (Metasul) or a MoP (Protasul) bearing. After 16 years, 38 patients had died and 4 had undergone revision surgery. 13 patients were unavailable for clinical follow-up, leaving 30 patients (n = 14 MoM and n = 16 MoP) for analysis of metal ion concentrations and clinical outcome. Results - 15-year implant survival was similar in both groups (MoM 96% [95% CI 88-100] versus MoP 97% [95% CI 91-100]). The mean serum cobalt concentration was 4-fold higher in the MoM (1.5 μg/L) compared with the MoP cohort (0.4 μg/L, p < 0.001) and the mean chromium concentration was double in the MoM (2.2 μg/L) compared with the MoP cohort (1.0 μg/L, p = 0.05). Mean creatinine levels were similar in both groups (MoM 93 μmol/L versus MoP 92 μmol/L). Harris hip scores differed only marginally between the MoM and MoP cohorts. Interpretation - This is the longest follow-up of a randomized trial on 28-mm MoM articulations, and although implant survival in the 2 groups was similar, metal ion concentrations remained elevated in the MoM cohort even in the long term.

MRI Findings in Patients After Small-Head Metal-on-Metal Total Hip Arthroplasty with a Minimum Follow-up of 10 Years

BACKGROUND

Concern has been raised about the late onset of adverse reactions to metal debris (ARMD) in patients with a small-head metal-on-metal total hip replacement. The aims of this study were to assess the frequency and characteristic appearance of ARMD in patients with a small-head (28-mm) metal-on-metal total hip replacement and elevated blood ion levels (>1 μg/L) after a minimum follow-up of 10 years and to analyze the possible risk factors associated with the prevalence of these lesions.

METHODS

In the present study, we used metal artifact reduction sequence magnetic resonance imaging (MARS MRI) to investigate the cases of 53 patients (66 hips) with a small-head (28-mm) metal-on-metal total hip replacement and elevated blood ion levels at a mean follow-up interval of 15.5 years (range, 10.6 to 19.3 years). Whole blood metal ion levels (cobalt and chromium), clinical outcome scores (Harris hip score), and radiographs were obtained for each patient. Tissue samples from patients who had revision surgery were histologically examined.

RESULTS

MARS MRI revealed ARMD in 27 hips (41%). Most hips with ARMD (67%) were asymptomatic. ARMD were generally small, with a median lesion size of 2.3 cm (range, 0.3 to 71.4 cm) and predominantly cystic in nature. Multivariate regression analysis revealed positive correlation between cobalt ion levels and the presence of ARMD. In this case series, the risk for the development of ARMD was 2.87 times higher for every 1 μg/L increase of blood cobalt ion concentration (95% confidence interval, 1.01 to 8.17; p = 0.048).

CONCLUSIONS

In this case series, ARMD were seen in 41% of the hips following small-head metal-on-metal total hip arthroplasty at long-term follow-up, and most patients with ARMD were asymptomatic. Blood cobalt ion levels could be identified as a risk factor for ARMD. However, ARMD also occurred in patients with low metal ion levels. Further studies are necessary to investigate the role of ARMD in asymptomatic patients with this bearing type.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

3rd generation ceramic-on-ceramic cementless total hip arthroplasty: a minimum 10-year follow-up study

INTRODUCTION

3rd generation ceramic bearings were introduced in total hip arthroplasty (THA) with the potential to have better mechanical strength and wear properties than their predecessors. At present, there are few studies looking at the long-term results of this latest generation of ceramic bearings.The purpose of our study was to investigate the long-term clinical and radiographic results of 3rd generation ceramic-on-ceramic THA and the incidence of ceramic specific complications such as squeaking and bearing surface fracture.

METHODS

The database of the senior author (J.D.W.) was reviewed. A total of 126 hip replacements performed in 108 patients (average age 39.6 years) with an average follow-up of 12.1 years (10-16 years) was identified. Clinical notes and plain radiographs were reviewed. To measure function, patients were contacted and an Oxford Hip Questionnaire was completed. Patients were also directly questioned about the presence of squeaking or any other sounds from the hip. Radiographs were evaluated for signs of wear, osteolysis, loosening and heterotopic ossification. The abduction angle of the acetabular component was measured.

RESULTS

The average Oxford Hip Score was 39.8 out of 48. Survivorship at 10 years was 94.6% (95% CI) with revision for any cause as the endpoint. There was 1 femoral head fracture, no osteolysis, no squeaking and no detectable wear.

CONCLUSIONS

The good clinical and radiographic results for this series of patients are similar to other recent long-term studies looking at 3rd generation ceramic-on-ceramic THA. The results compare favourably with other bearing surfaces. The lack of osteolysis associated with this articulation is encouraging and may also make it a good choice for younger patients requiring total hip replacement.

Astaxanthin mitigates cobalt cytotoxicity in the MG-63 cells by modulating the oxidative stress

Background

With the re-popularity of metal-on-metal (MoM) bearing in recent years, the cobalt toxicity has been a cause for concern in the total hip replacement surgery by both physicians and patients.

Methods

MG-63 cell line was cultured in vitro and incubated with cobalt (II) chloride (CoCl₂) and/or with astaxanthin (ASX) for 24 h. MTT assay was conducted to evaluate the cell viability after cobalt exposure and ASX treatment. Fluorescence-activated cell sorting (FACS) analysis was performed to examine the reactive oxygen species (ROS) level. Quantitative real-time polymerase chain reaction (PCR) was adopted to determine the mRNA levels of related targets. And western blot analysis was used to examine the protein expressions. One-way ANOVA with posttest Newman-Keuls multiple comparisons was adopted to analysis all the obtained data.

Results

In the current study, ASX exhibited significant protective effect against the Co(II)-induced cytotoxicity in MG-63 cell line. We also found that ASX protected the cells against Co-induced apoptosis by regulating the expression of Bcl-2 family proteins. Besides, heme oxygenase 1 (HO-1) could be activated by Co exposure; ASX treatment significantly inhibited HO-1 activation, suppressing the oxidative stress induced by Co exposure. Moreover, c-Jun N-terminal Kinase (JNK) phosphorylation was shown to participate in the signaling pathway of the protective effect of ASX. However, knockdown of JNK expression by siRNA transfection or JNK inhibitor SP600125 treatment did not affect the protective effect of ASX against cobalt cytotoxicity in MG-63 cells.

Conclusions

ASX mitigated cobalt cytotoxicity in the MG-63 cells by modulating the oxidative stress. And ASX could be a promising therapy against cobalt toxicity in the hip articulation surgery.

Electronic supplementary material

The online version of this article (doi:10.1186/s40360-017-0166-1) contains supplementary material, which is available to authorized users.

Incidence of Adverse Reactions to Metal Debris From 28-mm Metal-on-Metal Total Hip Arthroplasties With Minimum 10 Years of Follow-Up: Clinical, Laboratory, and Ultrasound Assessment of 44 Cases

BACKGROUND

Total hip arthroplasty with metal-on-metal (MoM) bearings has been suspected to cause adverse reactions to metal debris (ARMD), with the incidence varying greatly by implant type and patient gender. The prevalence of ARMD from small-diameter MoM bearings in women is unknown, especially after 10 years of follow-up (FU).

METHODS

Cementless 28-mm MoM total hip arthroplasty bearings (Metasul) were implanted consecutively in 42 active women between 1996 and 2002. They were reviewed after a minimum of 10 years' FU with clinical, laboratory, radiological, and ultrasound assessments.

RESULTS

Mean FU was 15.9 years (range, 13-18). The mean Postel-Merle d'Aubigné and Oxford scores were 16.9 (range, 13-18) and 15.1 (range, 12-24), respectively, at FU. Mean cup inclination angle was 46.3° (range, 35°-57°). No femoral osteolysis was detected, but limited acetabular osteolysis (11%) over the screw holes occurred in 5 cases. No liquid or solid synovial reactions or ARMD were apparent on ultrasound, even in the 5 cases of pelvic osteolysis. Mean chromium levels were 1.32 μg/L (range, 0.1-7.9) and cobalt levels were 1.85 μg/L (range, 0.35-13.6). Cobalt was >3 μg/L in only 3 cases. The 15.9-year survivorship was 95% (range, 94.1%-98.9%).

CONCLUSION

Reliable results were obtained with 28-mm MoM bearings, notably in young, active patients. This implant configuration requires very accurate positioning. No ARMD was seen in this group at 16 years' FU.

Tribology of total hip arthroplasty prostheses: What an orthopaedic surgeon should know

Articulating components should minimise the generation of wear particles in order to optimize long-term survival of the prosthesis.

A good understanding of tribological properties helps the orthopaedic surgeon to choose the most suitable bearing for each individual patient.

Conventional and highly cross-linked polyethylene articulating either with metal or ceramic, ceramic-on-ceramic and metal-on-metal are the most commonly used bearing combinations.

All combinations of bearing surface have their advantages and disadvantages. An appraisal of the individual patient’s objectives should be part of the assessment of the best bearing surface.

Cite this article: Rieker CB. Tribology of total hip arthroplasty prostheses: what an orthopaedic surgeon should know. EFORT Open Rev 2016;1:52-57. DOI: 10.1302/2058-5241.1.000004.

The Role of Metal-on-Metal Bearings in Total Hip Arthroplasty and Hip Resurfacing: Review Article

BACKGROUND

The current role of metal-on-metal (MoM) bearings in hip arthroplasty remains controversial. The low wear offered by MoM bearings compared to metal-on-polyethylene and the possibility of a lower risk of dislocation with larger head sizes, encouraged a trend towards the re-introduction of the MoM bearing couple. However, recent evidence has shown that not all designs of the MoM bearing have been successful.

QUESTIONS/PURPOSES

The purpose of this paper is to provide an update on the use of MoM bearings and address the following issues: (1) the reintroduction of metal-on-metal bearings in total hip arthroplasty, (2) the failure of metal-on-metal bearings in stemmed total hip arthroplasty, (3) the role of metal-on-metal hip resurfacing in modern orthopaedics and (4) metal-on-metal hip resurfacing versus total hip arthroplasty.

METHODS

A literature search strategy was conducted using various search terms in MEDLINE and Embase. The highest quality articles that met the inclusion criteria and best answered the topics of focus of this review were selected. Key search terms included 'metal-on-metal', 'total hip arthroplasty' and 'hip resurfacing'.

RESULTS

The initial search retrieved 1240 articles. Twenty-two articles were selected and used in the review.

CONCLUSION

Metal-on-metal hip resurfacing is still a suitable treatment option in specific patient populations with the appropriate implant design and surgical skill, while stemmed metal-on-metal total hip arthroplasty should be avoided in all patient populations. Continued follow-up of patients undergoing metal-on-metal hip resurfacing is critical in order to further understand the long-term outcomes of these patients and why certain complications tend to occur with this procedure.

Revision rates for metal-on-metal hip resurfacing and metal-on-metal total hip arthroplasty - a systematic review

PURPOSE

To compare revision rates of metal-on-metal (MoM) hip resurfacing (HRS) and MoM total hip arthroplasty (THA), as well as the primary causes for revisions.

METHODS

The PubMed database was queried for potentially relevant articles addressing MoMTHA and MoMHRS, a total of 51 articles were included.

RESULTS

The review includes a total number of 5,399 MoMHRS and 3,244 THA prosthesis and the reasons for prosthesis failure were divided into 7 categories and the main causes discussed. The overall MoMTHA revision rate was 4.7% after 6.9 years. MoMHRS revision rate was 5.9% after 5.7 years. The odds ratio was 1.25 (1.03:1.53) 95% CI (p = 0.03) (MoMHRS vs. MoMTHA).The studies of hip prostheses were separated into 2 categories of short- and long-term (more or less than 5 years). Short-term revision rate for MoMTHA was 4.5% after 4.8 years, and for MoMHRS 4.0% after 4.2 years. The odds ratio was 1.09 (0.82:1.43) 95% CI (0 = 0.56) (MoMTHA vs. MoMHRS). Long-term revision rate for MoMTHA was 5.2% after 7.7 years and 8.2% after 7.6 years for MoMHRS. The odds ratio was 1.58 (1.53:1.96) 95% CI (p = 0.0001) (MoMHRS vs. MoMTHA).Revision causes were divided into 7 main categories. The most common cause for revision for both MoMTHA and MoMHRS was loosening 47.6% vs. 37.7%, fracture (MoMTHA 7.69%; MoMHRS 19.62%), metal reactions (MoMTHA 7.69%; MoMHRS 26.92%) infection (MoMTHA 12.08%; MoMHRS 6.54%), instability (MoMTHA 9.13%; MoMHRS 2.69%), manufacturer defect 6.73% for MoMTHA and nonreported for MoMHRS, and miscellaneous (MoMTHA 7.69%; MoMHRS 6.54%) was stated.

INTERPRETATION

The comparison of MoMHRS and MoMTHA revision rates showed no difference in the short term, however in the longer term, the revision rate of MoMHRS was significantly higher than for MoMTHA. The linear increase in revision rate of MoMHRS may indicate a progression in failure.

Metal on Metal or Ceramic on Ceramic for Cementless Total Hip Arthroplasty: A Meta-Analysis

BACKGROUND

Hard bearings, metal on metal (MOM) and ceramic on ceramic (COC), have been developed to overcome polyethylene wear-related osteolysis, but comparisons between these 2 hard bearings are limited. We performed a meta-analysis to determine revision rates for (1) any reason, (2) aseptic loosening, (3) periprosthetic joint infection (PJI), and (4) recurrent dislocation between MOM and COC bearings in cementless total hip arthroplasty.

METHODS

This analysis included 3 studies comparing COC and MOM bearings and 56 studies reporting outcomes of MOM or COC bearings. We conducted a comparison meta-analysis (with a fixed-effects model) on the 3 comparative studies and a proportional meta-analysis on the data from the 59 articles to determine a consensus.

RESULTS

In the comparison meta-analysis, MOM showed higher revision rate than COC for any reason (odds ratio = 2.39, P = .046) and PJI (odds ratio = 6.21, P = .015). In the proportion meta-analysis, the MOM group showed significantly higher revision rate than COC group for any reason, aseptic loosening, and PJI.

CONCLUSION

MOM bearings were associated with a higher risk of revision for any reason and PJI than COC bearings after cementless total hip arthroplasty.

Metal-on-metal total hip arthroplasty: risk factors for pseudotumours and clinical systematic evaluation

The potential advantages of contemporary MoM THA implants include less volumetric wear with subsequent reduction of polyethylene wear-induced osteolysis and greater component stability with use of large-diameter femoral heads. However, there have been concerns regarding significantly elevated revision rates in MoM THA due to MoM-related complications such as adverse local tissue reaction (pseudotumour) formation. The increased failure rate in MoM hip arthroplasty is associated with the generation of biologically active, nanometer sized metal particles from the MoM bearing surfaces and taper junctions, which result in the development of a localized, adverse periprosthetic soft tissue response. The focus of this article is to provide an update on (1) implant, surgical and patient factors associated with adverse local tissue reactions (pseudotumours) and (2) the clinical systematic evaluation and management of patients with MoM hip arthroplasty based on the currently available evidence. There should be a low threshold to conduct a systematic clinical evaluation of patients with MoM hip arthroplasty as early recognition and diagnosis will allow the initiation of prompt and appropriate treatment. As a symptomatic MoM total hip arthroplasty may have intrinsic and extrinsic causes, patients should be evaluated systematically, utilizing risk stratification algorithms. Although specialized laboratory tests such as metal ion levels and cross sectional imaging modalities such as MARS MRI can be used to facilitate clinical decision making, over-reliance on any single investigative tool in the clinical decision-making process should be avoided. Further research is required to obtain a better understanding of implant and patient risk factors associated with tribocorrosion in MoM total hip arthroplasty.

Cementless Total Hip Arthroplasty With Metasul Bearings Provides Good Results in Active Young Patients: A Concise Followup

BACKGROUND

A primary concern of younger, more active patients who have undergone total hip arthroplasty (THA) is the longevity of the implant. Cementless fixation and hard-on-hard bearings are recognized as options to enhance THA durability. Earlier, we published a series of 83 cementless primary THAs using 28-mm metal-on-metal (MoM) bearings in patients aged 50 years or younger; here we provide concise followup on that same group after an additional 8-year survey period.

QUESTIONS/PURPOSES

(1) What is the long-term survivorship of cementless primary THA using 28-mm MoM bearings in patients aged 50 years or younger? (2) What are the clinical and radiographic results of cementless THA in this active patient population? (3) Can any of the observed implant failures or adverse events be attributed to the metallic nature of the bearing couple?

METHODS

We retrospectively reviewed 83 cementless THAs performed in three institutions over a decade (1995-2004) in 68 patients with 28-mm MoM articulation. All patients (15 bilateral) had a median age of 42 years (range, 24-50 years) at the time of the index procedure and 56 of them (82% [70 hips]) had activity level graded Devane 4 or 5 before significant hip pain. A 28-mm Metasul™ articulation was used with an Alloclassic-SL™ cementless stem in all cases paired with three different cementless titanium acetabular components (one threaded and two press-fit cups) from the same manufacturer. Survivorship analysis was calculated according to Dobbs life table, patient clinical results were evaluated with use of the Postel-Merle d'Aubigné scoring system, radiographic analysis was performed by independent observers, and cobalt level was determined in whole blood.

RESULTS

The 15-year survivorship (33 hips at risk) for revision for any reasons (four hips) and for aseptic loosening (one hip) was 96% (95% confidence interval [CI], 81%-99%) and 99% (95% CI, 85%-99.9%), respectively. The median Merle d'Aubigné-Postel score remained stable at 17 points (range, 10-18). Thus far, we have not observed pseudotumors or other adverse reactions to metallic debris. Eight hips have undergone reoperation: trochanteric suture removal (one), psoas tendon impingement (two), and five revisions for periprosthetic fracture (one), late infection (two), acetabular osteolysis (one, as a result of polyethylene backside wear), and one hydroxyapatite-coated cup for aseptic loosening. None of the complications, failures, or revisions observed so far could directly be related to the metallic nature of the 28-mm Metasul bearings used in this selected group of patients.

CONCLUSIONS

The current survey at 13-year median followup has not yet indicated any long-term deleterious effects related to dissemination of metallic ions. Two senior authors continue to use 28- or 32-mm Metasul™ bearings with cementless THA components in young and active patient populations. Longer followup with a more sophisticated imaging study is necessary to confirm this so far positive report.

LEVEL OF EVIDENCE

Level IV, therapeutic study.

High Re-Operation Rates Using Conserve Metal-On-Metal Total Hip Articulations

Introduction:

Metal-on-metal hip articulations have been intensely debated after reports of adverse reactions and high failure rates. The aim of this study was to retrospectively evaluate the implant of a metal-on.metal total hip articulation (MOM THA) from a single manufacture in a two-center study.

Materials and Methods:

108 CONSERVE^® MOM THA were implanted in 92 patients between November 2005 and December 2010. Patients had at time of retrospective evaluation their journals reviewed for re-operations and adverse reactions.

Results:

20 hips were re-operated (18.4%) at a mean follow up of 53 months. 4 pseudotumors were diagnosed at time of follow up but no substantiated link was made between adverse reactions and re-operations.

Conclusion:

The high re-operation rates found in this study raised concern about the usage of the MOM THA and subsequently lead to the termination of implantation of this MOM THA at the two orthopaedic departments.

Adverse Reactions to Metal on Metal Are Not Exclusive to Large Heads in Total Hip Arthroplasty

BACKGROUND

There is some suggestion that smaller diameter heads in metal-on-metal total hip arthroplasty (MoM THA) may be less prone to the adverse reactions to metal debris (ARMD) seen with large-diameter heads.

QUESTIONS/PURPOSES

We reviewed our population of patients with small head (≤ 32 mm) MoM THA to determine (1) the frequency of ARMD; (2) potential risk factors for ARMD in this population; and (3) the etiology of revision and Kaplan-Meier survivorship with revision for all causes.

METHODS

Small-diameter head MoM devices were used in 9% (347 of 3753) of primary THAs during the study period (January 1996 to March 2005). We generally used these implants in younger, more active, higher-demand patients. Three hundred hips (258 patients) had MoM THA using a titanium modular acetabular component with a cobalt-chromium tapered insert and were available for review with minimum 2-year followup (mean, 10 years; range, 2-19 years). Complete followup was available in 86% of hips (300 of 347). Clinical records and radiographs were reviewed to determine the frequency and etiology of revision. Kaplan-Meier survivorship analysis was performed.

RESULTS

ARMD frequency was 5% (14 of 300 hips) and represented 70% (14 of 20) of revisions performed. Using multivariate analysis, no variable tested, including height, weight, body mass index, age, cup diameter, cup angle, use of screws, stem diameter, stem type, head diameter, preoperative clinical score, diagnosis, activity level, or sex, was significant as a risk factor for revision. Twenty hips have been revised: two for infection, four for aseptic loosening, and 14 for ARMD. Kaplan-Meier analysis revealed survival free of component revision for all causes was 95% at 10 years (95% confidence interval [CI], 91%-97%), 92% at 15 years (95% CI, 87%-95%), and 72% at 19 years (95% CI, 43%-90%), and survival free of component revision for aseptic causes was 96% at 10 years (95% CI, 92%-98%), 92% at 15 years (95% CI, 88%-95%), and 73% at 19 years (95% CI, 43%-90%).

CONCLUSIONS

The late onset and devastating nature of metal-related failures is concerning with this small-diameter MoM device. Although the liner is modular, it cannot be exchanged and full acetabular revision is required. Patients with all MoM THA devices should be encouraged to return for clinical and radiographic followup, and clinicians should maintain a low threshold to perform a systematic evaluation. Symptomatic patients should undergo thorough investigation and vigilant observation for ARMD.

LEVEL OF EVIDENCE

Level IV, therapeutic study.

Small diameter metal-on-metal total hip arthroplasty at 13 years - a follow-up study

INTRODUCTION

Theoretically, the properties of second-generation metal-on-metal (MoM) bearings are better for wear, osteolysis and longevity. However, follow-up studies of more than 10 years are rare, in particular with hybrid fixation (cemented stainless steel stems and cementless cup), therefore we evaluated the results of this combination after a mean follow-up of 12.8 years: (1) to analyze the survival rate, (2) to compare it with the survival rate in the same series after 6.4 years (95.8% cup, 94.8% stem), (3) to evaluate clinical and radiographic outcome and (4) to analyze these failures.

HYPOTHESIS

The number of revisions would increase after 10 years.

MATERIALS AND METHODS

We evaluated 106 total hip arthroplasties (THA) (Cedior™ press-fit cup with cemented Acora™ (n=50) and Exafit™ (n=56) stems and 28mm Metasul™ bearings performed between January 1999 and December 2002. The survival rate was calculated by the Kaplan-Meier method. The clinical assessment included the Postel Merle d'Aubigné (PMA) and Oxford scores. The radiographic assessment evaluated radiolucencies and osteolysis on standard X-rays. A histological analysis was only performed during revision THA.

RESULTS

After a mean 12.8 years of follow-up (10-16), 53 THA were reviewed in 48 patients. Thirteen THA revisions (14%) were performed including 11 aseptic revisions (5 stem fractures, 2 cases of impingement and 3 loosenings [1 bipolar and 3 cups] and one case of osteolysis). Overall survival, taking into account revision for aseptic loosening, was 87.6% (CI 95%=77.3 to 99.3%). The mean PMA and Oxford scores at the final follow-up were 17.6±0.8 points (16-18) and 16.5±5.2 points (12-38) respectively. The radiological follow-up mainly identified radiolucencies around the stem in Gruen zones 1 and 7 (17 and 21% respectively).

DISCUSSION

The survival rate of hybrid MoM THA in this series decreased after 10 years and is lower than studies evaluating cementless THA with the 28-mm Metasul™ bearings (90.9 to 100% survival). Although the clinical results are satisfactory, survival is lower. However, the role of MoM bearings is relative in these failures, in particular because trunnionoses (stainless steel stem with 28-mm head), impingement and especially 5-stem fractures were the main causes of failure.

LEVEL OF EVIDENCE

IV: retrospective study.

Ten to fifteen-year clinical and radiographic follow-up with a third-generation cementless stem in a young patient population

PURPOSE

Outcome data beyond 11 years of follow-up is not available for the third-generation Zweymüller femoral stem in combination with a polyethylene bearing. We report ten to 15-year results with this total hip arthroplasty (THA) combination in a young population.

METHODS

A retrospective, observational, non-randomised, single-centre, clinical observational study was conducted in which 311 primary THAs were performed in 276 patients between 1996 and 2000 using a third-generation Zweymüller stem. The mean age of the patients at operation was 47.4 years (range 18-77 years).

RESULTS

Stem survival for any reason was 93.5% after ten years and 89.6% after 13 years, and the probability of aseptic stem loosening was 98.7% at both ten and 13 years. The occurrence of femoral radiolucent lines was low, at just 17.2%. Minor femoral osteolysis was identified in 30% of patients and was attributed to polyethylene liner wear. Clinical and patient satisfaction outcomes were in line with previous investigations, and the rate of adverse events was low.

CONCLUSIONS

The third-generation Zweymüller stem shows good radiographic and clinical results and good longevity, including in the younger osteoarthritic patient. The use of low-wear bearings may further reduce the rate of osteolysis and wear-related revision in young and active patients.

Are younger patients undergoing THA appropriately characterized as active?

BACKGROUND

Surgeons perform THA to address a variety of conditions in younger patients, including osteoarthritis (OA), osteonecrosis, inflammatory arthritis, and congenital deformities. Younger patients aged 50 years or younger have been characterized as active in the literature, but a direct relationship between age and activity level has not been well substantiated. Younger patients with OA may engage in higher activity levels; however, associated medical conditions in patients with other surgical indications may not support a generalization that age is a surrogate for activity level. We recently evaluated these issues in younger patients undergoing total knee arthroplasty (TKA) and noted that the majority would not be considered active. Given this observation, we considered whether younger patients undergoing THA are characterized by high activity levels, which is relevant to understanding the long-term risk of wear-related failures.

QUESTIONS/PURPOSES

(1) Do demographic features of younger patients undergoing THA support high activity expectations? (2) Do preoperative or postoperative functional activity measures support projections that younger patients are active after THA?

METHODS

We retrospectively compared demographic characteristics and functional activity profiles (as determined by preoperative and postoperative UCLA activity scores, Harris hip scores [HHS], and SF-12 and WOMAC physical function subscores) of 704 patients who had undergone THA and were aged younger than 50 years (822 hips) with those of 484 patients (516 hips) aged between 65 and 75 years, who had undergone THA, with a minimum followup at 1 year after surgery (range, 12-160 months).

RESULTS

Compared with patients aged 65 to 75 years, younger patients undergoing THA were more often men (51%, 95% confidence interval [CI], 48.8%-53.2% versus 40%, 95% CI, 37.1%-42.9% women; p < 0.01) or had undergone surgery for osteonecrosis (29% versus 4%; 95% CI, 2.8%-5.2%; p < 0.001). Postoperative HHS, SF-12, and WOMAC scores were not appreciably different between the two patient groups. Compared with older patients, younger patients with OA had higher preoperative (5.0 ± 2.5 versus 3.9 ± 2.0, p < 0.001) and postoperative UCLA activity scores (6.8 ± 2.1 versus 5.3 ± 1.9, p < 0.001). Younger patients with diagnoses other than OA had slightly higher mean postoperative UCLA activity scores than older patients (6.0 ± 2.3 versus 5.3 ± 1.9; p < 0.001). Two hundred fifty-nine of 704 younger patients undergoing THA (37%; 95% CI, 34.9%-39.1%) returned to impact activity compared with 75 of 484 older patients undergoing THA (15.5%; 95% CI, 13.3%-17.7%) (p < 0.001).

CONCLUSIONS

Younger patients with OA are likely to return to high levels of activity after surgery, which may impact long-term wear-related implant survivorship. High activity levels are less common among younger patients with diagnoses other than OA. Age is not the ideal surrogate for activity level in patients considering THA; instead, specific activity-level measures should be used when discussing patient expectations pertaining to postoperative activity levels after arthroplasty.

LEVEL OF EVIDENCE

Level III, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Metal ion levels and functional results following resurfacing hip arthroplasty versus conventional small-diameter metal-on-metal total hip arthroplasty; a 3 to 5year follow-up of a randomized controlled trial

We present an update of a randomized controlled trial on 71 patients (<65 years) who received either a resurfacing hip arthroplasty (RHA) (n=38) or cementless 28-mm metal-on-metal (MoM) total hip arthroplasty (THA) (n=33). Metal ion levels and functional outcome scores were analyzed with a mean follow-up of 58 months (SD 8.1). No clear shifts in relatively good outcome was encountered between RHA and THA. Metal ion levels appear to equalize between groups after 3 years. Median cobalt and chromium remained below 1.3 μg/L throughout follow-up in both groups. Six revisions were performed, of which three for pseudotumor formation (one THA, two RHA). In conclusion there were no clinical differences between the two groups and metal ion levels were lower than other series remained low, however, pseudotumor formation was not eliminated.

Large fixed-size metal-on-metal total hip arthroplasty: higher serum metal ion levels in patients with pain

PURPOSE

Recently, concerns have arisen about metal-on-metal (MoM) total hip arthroplasty (THA). Therefore, the purpose of this cross-sectional cohort study was to describe the incidence of pain, pseudotumours, revisions and the relation between elevated metal ion levels, functional outcome and quality of life after MoM THA.

METHODS

In 351 patients, 377 MoM THA with a fixed-size 38-mm head were evaluated with a mean follow-up of 30 months (range 11-58). Evaluation included pain, serum metal ions, patient-reported questionnaires (Short Form-36 [SF-36], Hip disability and Osteoarthritis Outcome Score [HOOS] and the Oxford Hip Score [OHS]) and radiological imaging. Sixteen patients did not participate in the screening.

RESULTS

One hundred and eighteen (35 %) patients reported pain and showed significantly higher cobalt and chromium levels compared to patients without pain. Median serum cobalt levels were 4.4 μg/l (interquartile range [IQR] 6.6) and chromium levels were 3.6 μg/l (IQR 4.8). Patients with cobalt levels of ≤5 μg/l reported significantly better outcome on the SF-36 and HOOS. Fifty-seven pseudotumours were identified in 227 THAs. A revision rate of 19 % was observed.

CONCLUSIONS

In conclusion, 35 % of the patients experienced pain after MoM THA. These patients showed significantly higher serum metal ion levels. The patient-reported questionnaires indicated significantly better outcome in patients with cobalt levels ≤5 μg/l.