Ceramic Debris in Hip Prosthesis: Correlation Between Synovial Fluid and Joint Capsule

Detection of ceramic particles in synovial fluids allows early diagnosis of ceramic damage, but there is no evidence of a relationship between ceramic debris in the articular space and in the joint capsule. The aim of the present study is to verify if the particles isolated in the synovial fluid are comparable with those stored in the capsular tissue. Twenty-one patients were enrolled. Both synovial fluid and capsular samples were collected during revision surgery and ceramic particles were isolated and analyzed by scanning electron microscopy and energy-dispersive X-ray microanalysis. It resulted a significant correlation between the samples couples (18 out of 21). This study confirms that the synovial fluid analysis can give a clear definition of the presence of particles in the joint capsule.     

A Study for a retrieved implant of ceramic-on-ceramic total hip arthroplasty

A Mittelmeier-type ceramic on ceramic total hip arthroplasty (THA) was retrieved because of aseptic loosening 17 years after implantation. The extent of wear was assessed by scanning electron microscopy. The synovial fluid and the tissue surrounding the implant were also examined. Scanning electron microscopy analysis of the ball head showed that the main wear zone had grade IV wear. The stripe wear zones showed grain pullout regions (grade 5 wear). Pathologically, chronic inflammation was observed in the surrounding tissue. The debris particles in the synovial fluid were polygonal and approximately 3 x 4 microm. Thus, the Mittelmeier-type THA proved excellent wear resistance. Further longevity of ceramic on ceramic THA may indeed become a reality with improvement of the design and quality of alumina.     

Ferrographic analysis of synovial fluid in total hip replacement]

A synovial fluid analysis was carried out on 84 patients with total hip replacements, 53 of which were revision cases. The analysis was done using ferrography. An animal study was carried out whereby alumina ceramic, polyethylene and polymethyl methacrylate particles were inserted into the knees of rabbits, the synovial fluid of which was analysed. In addition, the synovium and surrounding tissues were histologically analysed. One week after insertion of the particulate debris only a few particles were noted in the synovial fluid and none at two weeks post insertion. However, these particles were noted in the synovium and surrounding tissues. Therefore, it was concluded that wear particles, following total hip replacement, may be encapsulated in the early period by the capsule and synovium, and have no adverse affect on the lubricating kinetics of the joint. It is postulated that the difference in tissue reaction to each of these particles may be responsible for the subsequent loosening.     

Monocyte chemoattractant protein 1 expression in synovial fluid of patients with total hip arthroplasty

Monocyte chemoattractant protein 1 (MCP-1) is a member of the chemokines family that stimulates monocyte chemotaxis and whose expression is induced during osseous inflammation. Total hip arthroplasty (THA) now uses ceramic-on-ceramic (cer-cer) or metal-on-metal (met-met) coupling that is considered the bearing of new generation, with improved performance compared with the previous polyethylene bearings. While the ceramic on ceramic is universally considered highly biocompatible, met-met coupling can induce hypersensitivity correlated to immunological response. This study aimed at quantifying the MCP-1 levels in synovial fluid of THA patients with these two articular couplings; synovial fluid of osteoarthritic patients who underwent primary THA was used as a control. The presence of wear particles originating from the prostheses was also assessed in the synovial fluid by scanning electron microscopy and energy dispersive X-ray spectroscopy. The MCP-1 levels in the synovial fluid of 17 patients with met-met coupling were significantly higher than in 13 patients with cer-cer coupling and in seven controls; median MCP-1 level was 919 pg/mL in the cer-cer group, 4274 pg/mL in the met-met group, and 326 pg/mL in the control group. No correlation was found between MCP-1 levels and the presence of wear particles in the synovial fluid, time from surgery, or periprosthetic osteolysis. We conclude that the presence of the prosthesis is responsible for an increase in the level of MCP-1; moreover, the significantly higher level of this chemokine in met-met coupling can be related to inflammatory and possibly hypersensitivity processes induced by metal ions.     

Osteolysis in third-generation alumina ceramic-on-ceramic hip bearings with severe impingement and titanium metallosis

The most common cause of long-term failure of total hip arthroplasty is osteolysis and aseptic loosening secondary to wear debris. Combinations of hard materials such as ceramic-on-ceramic generate smaller volumes of particulate wear debris than traditional combinations such as metal-on-polyethylene. We describe 2 cases where osteolysis arose in hips with third-generation alumina ceramic-on-ceramic couplings. Periarticular tissue in both cases contained titanium wear debris due to impingement of the neck of the titanium femoral component against the rim of the titanium shell and ceramic debris from edge loading wear (stripe wear) of the ceramic. It is not clear whether the titanium debris, the ceramic debris, or both caused the osteolysis. These cases illustrate that the risk of osteolysis persists, even with third-generation alumina ceramics.     

Morphologic characteristics of periprosthetic tissues from hip prostheses with ceramic-ceramic couples: A comparative histologic investigation of 18 revision and 30 autopsy cases

Pseudocapsules and interface membranes from 18 revision cases having hip prostheses with ceramic-ceramic couples and 30 autopsy specimens (6 with ceramic-ceramic couples, 7 with ceramic-polyethylene combinations and 17 with metal-polyethylene combinations) were histomorphologically analyzed, including a semiquantitative grading of the wear particles and histologic changes. Unlike the revision cases, which usually showed ceramic wear particles in the adjacent tissues, only half of the autopsy cases revealed ceramic wear. As compared to the ceramic-polyethylene and metal-polyethylene couples, the alumina on alumina combinations showed a thinner synovial layer with reduced villous transformation and smaller infiltrates of macrophages and necroses, which can be explained by the absence of polyethylene wear. Metal-polyethylene couplings produced more than twice as many polyethylene wear particles with correspondingly more marked foreign body reaction than the ceramic-polyethylene couplings.     

Morphologic characteristics of periprosthetic tissues from hip prostheses with ceramic-ceramic couples: A comparative histologic investigation of 18 revision and 30 autopsy cases

Pseudocapsules and interface membranes from 18 revision cases having hip prostheses with ceramic-ceramic couples and 30 autopsy specimens (6 with ceramic-ceramic couples, 7 with ceramic-polyethylene combinations and 17 with metal-polyethylene combinations) were histomorphologically analyzed, including a semiquantitative grading of the wear particles and histologic changes. Unlike the revision cases, which usually showed ceramic wear particles in the adjacent tissues, only half of the autopsy cases revealed ceramic wear. As compared to the ceramic-polyethylene and metal-polyethylene couples, the alumina on alumina combinations showed a thinner synovial layer with reduced villous transformation and smaller infiltrates of macrophages and necroses, which can be explained by the absence of polyethylene wear. Metal-polyethylene couplings produced more than twice as many polyethylene wear particles with correspondingly more marked foreign body reaction than the ceramic-polyethylene couplings.     

Morphologic characteristics of periprosthetic tissues from hip prostheses with ceramic-ceramic couples: a comparative histologic investigation of 18 revision and 30 autopsy cases

Pseudocapsules and interface membranes from 18 revision cases having hip prostheses with ceramic-ceramic couples and 30 autopsy specimens (6 with ceramic-ceramic couples, 7 with ceramic-polyethylene combinations and 17 with metal-polyethylene combinations) were histomorphologically analyzed, including a semiquantitative grading of the wear particles and histologic changes. Unlike the revision cases, which usually showed ceramic wear particles in the adjacent tissues, only half of the autopsy cases revealed ceramic wear. As compared to the ceramic-polyethylene and metal-polyethylene couples, the alumina on alumina combinations showed a thinner synovial layer with reduced villous transformation and smaller infiltrates of macrophages and necroses, which can be explained by the absence of polyethylene wear. Metal-polyethylene couplings produced more than twice as many polyethylene wear particles with correspondingly more marked foreign body reaction than the ceramic-polyethylene couplings.     

Primary Ceramic-on-ceramic Total Hip Arthroplasty Using a 32-mm Ceramic Head With a Titanium-alloy Sleeve

Background

Modern ceramic-on-ceramic bearings have become attractive alternatives to conventional polyethylene in total hip arthroplasty (THA) as a result of their low wear and minimal particle production. However, 28-mm heads in ceramic-on-ceramic bearing couples have been associated with ceramic fracture. To address these issues, 32-mm and larger ceramic heads with a titanium-alloy sleeve have been introduced, although limited data are available on their durability and clinical outcomes.

Questions/purposes

We determined (1) the survivorship of the primary ceramic-on-ceramic THA using a 32-mm ceramic head with a titanium-alloy sleeve at a minimum followup of 5 years; (2) Harris hip scores; (3) the incidence of ceramic fracture and noisy hip; and (4) the proportion of hips showing radiographic evidence of osteolysis.

Methods

From November 2005 to August 2009, we performed 301 ceramic-on-ceramic THAs using a 32-mm ceramic head with a titanium-alloy sleeve in 270 patients. Of these, 12 patients (12 hips [4%]) died from problems unrelated to surgery and 13 patients (15 hips [5%]) were lost during followup before a minimum of 5 years had been reached, leaving 245 patients who had 274 THAs with a minimum followup of 5 years (mean, 6.5 years; range, 5–9 years) in this retrospective analysis. During the study period, 30% (301 of 997 hips) were performed with this articulation based on the operating surgeon’s discretion. The mean patient age at the time of surgery was 55 years (range, 16–82 years). All operations were performed at a single center. All of the ceramic implants were hot isostatic-pressed, laser-marked, proof-tested third-generation alumina. We determined the implant survival, Harris hip scores, incidence of ceramic fracture or noisy hips (based on a questionnaire), and presence of osteolysis.

Results

The survival rate of ceramic-on-ceramic bearings in primary THA using a 32-mm ceramic head with a titanium-alloy sleeve was 98% (95% confidence interval, 96%–100%) at 9 years. The Harris hip score improved from a mean of 47 points preoperatively to 93 points at last followup. One ceramic head fractured at 6 years postoperatively. No ceramic liners fractured. Audible hip clicking and squeaking were identified in four hips and one hip, respectively. Osteolysis was detected in three hips, but none had symptoms.

Conclusions

Primary ceramic-on-ceramic THA using a 32-mm ceramic head with a titanium-alloy sleeve has a survivorship of 98% at 9-year followup. Nevertheless, surgeons should be aware of the potential risks of ceramic fracture, noise, and osteolysis associated with the use of a ceramic head with a titanium-alloy sleeve.

Level of Evidence

Level IV, therapeutic study.     

H/G非骨水泥人工全髋关节置换术后聚乙烯内杯磨损临床研究

目的 对H/G非骨水泥人工全髋关节置换术后聚乙烯内杯的磨损及髋臼周围骨溶解的情况进行总结.方法 我院1991至1995年共进行58例(65髋)H/G非骨水泥人工全髋关节置换,其中35例(40髋)获得10年以上随访.对这35例(40髋)患者获得随访的病例,采用计算机数字化方法测量髋臼聚乙烯内杯的二维线性磨损.结果 35例40髋均有不同程度的磨损,磨损范围2～8 mm,平均磨损为(0.32±0.31)mm/年.10髋聚乙烯磨损超过6 mm,髋臼假体周围的骨溶解严重,并伴有金属假体的移位,其中5髋聚乙烯内杯完伞磨透,金属股骨头与金属髋臼相接触;5髋聚乙烯内杯磨损严重伴明显骨溶解,内杯松动.2髋聚乙烯内杯脱位.共实施翻修手术12例,包括更换聚乙烯内杯和金属股骨头2例、金属闩杯翻修2例、全髋翻修8例.28髋在髋臼侧发现骨溶解,其中14髋股骨侧亦有骨溶解发生.结论 本组病例所观测到的H/G髋臼聚乙烯内杯的磨损程度超过文献所报道,而且由于磨损产生的大量磨屑,导致假体周围出现明显骨溶解,直接影响到假体的稳定.关节置换术后应定期随访,避免出现严重骨溶解后增加翻修手术的困难.     

Uncemented Primary Total Hip Arthroplasty,Presentation of Pain,and Expression of Osteonectin

Osteonectin (ON) is an important matrix glycoprotein highly expressed in bone. In several in vitro and animal model studies, ON was used as indicator of the state of osseointegration of implanted devices. There are, however, no studies on ON expression in the synovial fluid of patients with total hip joint replacement (THJR). The purpose of our study was to determine the ON concentration in synovial fluid from three groups of patients: primary uncemented THJR with hip pain (“pain” group; n = 15) and without pain (“no‐pain” group; n = 12), and patients with osteoarthitis scheduled to receive a primary THJR (control group; n = 5). For the prosthesized groups, the statistical nature of the correlation between ON concentration and patient age, in situ life of the THJR, presence of periprosthetic osteolysis, and presence of debris in the synovial fluid was individually investigated. ON concentration was determined using enzyme‐linked immunosorbent assay, the presence of periprosthetic osteolysis was established using X‐radiography and Engh's criteria, and the presence of debris was determined using digestion and EDX spectroscopy. ON concentration was significantly lower in the “pain” group compared with the “no‐pain” one (median values 19.0 and 53.2 ng/mL, respectively). ON concentration in the control group (median value: 16.9 ng/mL) was comparable with that reported in the literature. In the prosthesized groups, ON concentration was not correlated with patient age, in situ life of the prosthesis, presence of periprosthetic osteolysis, or presence of debris in the synovial fluid. Our results suggest that cases of unexplained pain in THJR patients could be treated by paying special attention to the osseointegration status of the implant by using ON concentration as an early indicator of this status.     

Bilateral synovitis in symptomatic unilateral transient synovitis of the hip: An ultrasonographic study in 56 children

56 children with a clinical diagnosis of unilateral transient synovitis of the hip underwent bilateral sonographic assessment. On the anterior scan, the distance between the femoral neck and the fibrous joint capsule was measured. This distance, which we call the synovial capsular complex distance, was compared with age-dependent normal values. An in-creased distance was found in all 56 symptomatic hips (mean 10 mm, SD 1.8). This distance was also increased in 14 hips on the contralateral side (mean 8 mm, SD 1.6). An effusion was demonstrated in 53 symptomatic hips and in 8 hips on the contralateral side. These findings indicate that in one quarter of children with symptoms of unilateral transient synovitis the contralateral hip may have an increased synovial capsular complex distance due to synovial swelling or joint effusion, suggesting an asymptomatic synovitis. We therefore recommend a comparison of the synovial capsular complex distance on the symptomatic side with age-related normal values, in addition to a comparison with the asymptomatic hip.     

New experience with alumina-on-alumina ceramic bearings for total hip arthroplasty

A major challenge for total hip arthroplasty is to minimize wear and osteolysis in young, active patients. Alumina ceramic bearings have shown superior wear resistance and lubrication and do not carry the risk of ion release. In a prospective randomized study, 514 hips were implanted. All patients (average age, 53 years) received the same press-fit hydroxyapatite coated femoral stem; two thirds (345 hips) received alumina ceramic bearings, and one third (169 hips) received a cobalt-chrome-on-polyethylene bearing. At a mean follow-up of 35.2 months (range, 24-48 months), there was no significant difference in clinical performance between the patient cohorts. No ceramic fracture or alumina ceramic bearing failure occurred. This new experience involves the use of improved ceramic materials and new design considerations that eliminate the risks and complications of past experiences with ceramic implants and provides a safe bearing option for young patients.     

Catastrophic failure of an uncemented acetabular component due to high wear and osteolysisAn analysis of 154 Omnifit prostheses with mean 6-year follow-up

Background?The purposes of this study were (1) to evaluate the wear pattern of the hydroxyapatite-coated “Dual Radius” Omnifit cup, (2) to investigate whether wear is correlated to any demographic or prosthesis-related factors, and (3) to describe micromotion of both the cup and the stem.Patients and methods?154 hips were implanted between 1990 and 1996 and followed for an average of 6 years. Wear was measured according to the “Charnley-duo” method and, in 79 hips, with radiostereometry (RSA). RSA was also used to evaluate micromotion. We analyzed the femoral heads using scanning electron microscopy, energy dispersive X-ray spectroscopy and an atomic force microscope.Result?66 cups were revised and had a mean annual wear of 0.32?mm compared to 0.12?mm in hips not revised. Osteolytic processes were observed in 35 hips but at revision osteolysis was present in 51 cases. 43/66 sockets were loose. Micromotion evaluated by RSA, weight, age, side, size of cup, screws, polyethylene thickness or shelf-life of the polyethylene did not correlate to wear, whereas male gender did.Interpretation?It is still unclear why about half of our cases had an abnormal wear rate. Annual wear exceeding 0.2?mm is prognostic of late failure and should be considered a warning sign.     

Metal Artifact Reduction Sequence Magnetic Resonance Imaging Abnormalities in Asymptomatic Patients With a Ceramic-on-Ceramic Total Hip Replacement

BackgroundMetal artifact reduction sequence (MARS) magnetic resonance imaging (MRI) has recently gained increased utilization as a screening modality in patients with a total hip arthroplasty (THA). Fluid collections have been documented in asymptomatic patients with various bearing surfaces. The purpose of this study is to determine the frequency and types of MARS MRI-documented abnormalities in asymptomatic patients with a ceramic-on-ceramic (CoC) THA.MethodsThirty-seven patients (42 hips) with a minimum 2-year follow-up after THA with CoC THA implants were enrolled in this study. The inclusion criteria were the absence of hip pain and the availability of appropriate follow-up radiographs. All patients underwent a MARS MRI. Abnormalities were documented using a previously described method.ResultsFluid collections were observed in 8 (19%) asymptomatic hips in this cohort. Four of the 8 hips demonstrated intracapsular synovitis, and 3 of these hips had a thickened synovium. Extra-articular fluid collections with direct intra-articular communication were identified in 4 hips, with 2 of these hips demonstrating synovial thickening. No signs of osteolysis were noted on radiographs or the MARS MRI scans.ConclusionAsymptomatic fluid collections occur in patients after CoC THA similar to other bearing surfaces. We continue to follow these patients in an effort to determine the clinical significance and natural history of these findings.Level of EvidenceDiagnostic Level IV.     

Uncemented total hip arthroplasty using the CLS stem: A titanium alloy implant with a corundum blast finish: Results at a mean 6 years in a prospective study

An uncemented titanium alloy stem with a corundum blast finish and an uncemented titanium fibermetal mesh socket were implanted in a series of 57 hips. These prostheses were selected for use in the youngest, most active, and/or heaviest candidates for total hip arthroplasty. Fifty hips were available for study at a minimum 60 months. At a mean 6 years, 92% of the hips were rated good or excellent. The mean Harris hip score was 92. One patient experienced mild thigh pain. The corundum blast finish was associated with reliable implant stability. Survival analysis predicted a 96% rate of implant survival at 92 months. Loss of bone density was rated mild, minimal, or none in 88% of the hips. Three hips developed severe bone loss due to systemic disease. Polyethylene wear was measurable in 86% of the hips. Twenty hips developed focal proximal femoral bone erosions. One hip had endosteal cavitation distal to zone 7. The presence of proximal femoral erosions or endosteal cavitation correlated positively with the presence of measurable polyethylene wear. The limited and proximal distribution of femoral bone erosion despite evidence of extensive polyethylene wear suggested that bone apposition to the corundum blast finish resulted in a barrier to migration of wear debris.     

Ceramic-on-Ceramic Total Hip Arthroplasty: Minimum of Six-Year Follow-up Study

Background

This study examines the clinical and radiologic results of ceramic-on-ceramic total hip arthroplasties with regard to wear, osteolysis, and fracture of the ceramic after a minimum follow-up of six years.

Methods

We evaluated the results of a consecutive series of 148 primary ceramic-on-ceramic total hip arthroplasties that had been performed between May 2001 and October 2005 in 142 patients. The mean age was 57.2 years (range, 23 to 81 years). The mean follow-up period was 7.8 years (range, 6.1 to 10.1 years). Preoperative diagnosis was avascular necrosis in 77 hips (52%), degenerative arthritis in 36 hips (24.3%), femur neck fracture in 18 hips (12.2%), rheumatoid arthritis in 15 hips (10.1%), and septic hip sequelae in 2 hips (1.4%). Clinical results were evaluated with the Harris hip score, and the presence of postoperative groin or thigh pain. Radiologic analysis was done with special attention in terms of wear, periprosthetic osteolysis, and ceramic failures.

Results

The mean Harris hip score improved from 58.3 (range, 10 to 73) to 92.5 (range, 79 to 100) on the latest follow-up evaluation. At final follow-up, groin pain was found in 4 hips (2.7%), and thigh pain was found in 6 hips (4.1%). Radiologically, all femoral stems demonstrated stable fixations without loosening. Radiolucent lines were observed around the stem in 25 hips (16.9%), and around the cup in 4 hips (2.7%). Endosteal new bone formation was observed around the stem in 95 hips (64.2%) and around the cup in 88 hips (59.5%). No osteolysis was observed around the stem and cup. There were 2 hips (1.4%) of inclination changes of acetabular cup, 2 hips (1.4%) of hip dislocation, 1 hip (0.7%) of ceramic head fracture, and 1 hip (0.7%) of squeaking. The Kaplan-Meier survival rate of the prostheses was 98.1% at postoperative 7.8 years.

Conclusions

The ceramic-on-ceramic total hip arthroplasty produced excellent clinical results and implant survival rates with no detectable osteolysis on a minimum six-year follow-up study. The ceramic-on-ceramic couplings could be a reasonable option of primary total hip arthroplasty for variable indications.     

Alumina-on-alumina total hip arthroplasty. A five-year minimum follow-up study

BACKGROUND: Ceramic-on-ceramic couplings are attractive alternative bearing surfaces that have been reported to eliminate or reduce problems related to polyethylene wear debris. Disappointing experiences with alumina ceramic bearings in the past have led to many improvements in the manufacture and design of ceramic implants. The purpose of the present study was to report the results of contemporary alumina-on-alumina total hip arthroplasties with regard to wear, osteolysis, and fracture of the ceramic after a minimum duration of follow-up of five years. METHODS: We evaluated the results of a consecutive series of 100 primary alumina-on-alumina total hip arthroplasties that had been performed with use of a metal-backed socket and a cementless stem in eighty-four patients. All of the patients were sixty-five years of age or younger (mean age, forty-one years), and a single surgeon performed all of the procedures. After a minimum duration of follow-up of sixty months, one patient (one hip) had died and four patients (six hips) had been lost to follow-up, leaving a total of seventy-nine patients (ninety-three hips) available for study. All of these patients were evaluated clinically and radiographically with special attention to wear, periprosthetic osteolysis, and ceramic failure. RESULTS: The mean Harris hip score was 97 points at the time of the latest follow-up evaluation. All prostheses demonstrated radiographic evidence of bone ingrowth. No implant was loose radiographically, and no implant was revised. Ceramic wear was not detectable in the thirty-seven hips in which the femoral head could be differentiated from the cup on radiographs. Periprosthetic osteolysis was not observed in any hip. A fracture of the alumina femoral head and a peripheral chip fracture of the alumina insert occurred in one hip following a motor-vehicle accident. CONCLUSIONS: The results of contemporary alumina-on-alumina total hip arthroplasty with a metal-backed socket and a cementless stem were encouraging after a minimum duration of follow-up of five years. We believe that these improved alumina-on-alumina bearing implants offer a promising option for younger, active patients.     

The Result of Revision Total Hip Arthroplasty in Patients with Metallosis Following a Catastrophic Failure of a Polyethylene Liner

BackgroundWear cannot be completely prevented after total hip arthroplasty. If severe polyethylene (PE) liner wear develops, the so-called catastrophic failure occurs and metallosis develops. We postulated that longevity of the new implant may be affected after revision surgery for metallosis following a catastrophic failure of a PE liner due to the substantial amount of PE wear particles and infiltration of the metal particles in this catastrophic condition.MethodsTwenty-three hips of 23 patients were identified because they showed metallosis during revision total hip arthroplasties performed in Seoul National University Hospital between January 1996 and August 2004. They were followed for at least 6.5 years after the index revision total hip arthroplasty. The clinical and radiological results of revision total hip arthroplasties in these patients were evaluated.ResultsThe median Harris hip score increased from 60 points before revision total hip arthroplasties to 90 points at the final follow-up. Osteolysis was detected at an average of 9.3 years after revision total hip arthroplasties in 13 hips and acetabular cup loosening at average 9.8 years after revision total hip arthroplasties in 9 hips. With radiographic evidence of osteolysis and loosening as the end points, the 15-year survival rates were 28.2% and 56.0%, respectively.ConclusionsThe survival rate of revision total hip arthroplasty in patients with metallosis following a catastrophic failure of a PE liner was low.     

Mittelmeier ceramic—ceramic prosthesis after 10 years

The clinical status of 83 Mittelmeier ceramic—ceramic (Mark II) cementless total hip prostheses (Autophor, Osteo AG, Selzach, Switzerland) implanted between 1978 and 1984 was analyzed. Retrieved tissue from the revised hips was studied histologically. The mean patient age was 47.5 years (range, 19–71 years). One or both components of 12 hips were revised (16% at 16 years in the survival study). Eleven acetabular components and seven stems were revised, with three of the sockets fractured. The mean follow-up period for the patients with unrevised hips was 12.3 years. Osseointegration was uncommon in both the cup and stem. Radiographic cup loosening was observed in 53% of hips at 16 years in the survival study, with most having a complete radiolucent line of 2 mm around the cup. Radiographic stem loosening appeared in 15% of hips at 16 years. Fibrous stable fixation was present in 64% of stems. Significant radiographic acetabular wear was not observed in any hip. The Mittelmeier Mark II prosthesis had worse long-term results than reported with cemented or other uncemented prostheses. Although there was no significant acetabular wear, intracellular ceramic wear debris was seen in the retrieved tissues.