Alumina-on-alumina hip arthroplasty in patients younger than 30 years old

Cementless Ceramic-on-Ceramic Total Hip Replacement in Children and Adolescents

Background: total hip replacement (THR) is a rare surgical option in children and adolescents with disabling hip diseases. The aim of this study is to report results from a retrospective cohort of patients aged 18 years or less who underwent cementless Ceramic-on-Ceramic (CoC) THR at a single institution, investigating clinical and radiographic outcomes, survival rates, and reasons for revision of the implants. Materials and methods: we queried the Registry of Prosthetic Orthopedic Implants (RIPO) to identify all children and adolescents undergoing THR between 2000 and 2019 at a single Institution. Inclusion criteria were patients undergoing cementless CoC THR, aged less than 18 years at surgery, followed for at least 2 years. Sixty-eight patients (74 hips) matched all the inclusion criteria and were enrolled in the study. We assessed the clinical and radiographic outcomes, the rate of complications, the survival rate, and reasons for revision of the implants. Results: The mean follow-up was 6.6 ± 4.4 years (range 2-20). The most frequent reason for THR was post-traumatic or chemotherapy-induced avascular necrosis (38%). The overall survival rate of the cohort was 97.6% (95% CI: 84.9-99.7%) at 5 years of follow-up, 94.4% (95% CI: 79.8-98.6%) at 10 years and 15 years of follow-up. Two THR in two patients (2.7%) required revision. With the numbers available, Cox regression analysis could not detect any significant interaction between preoperative or intraoperative variables and implant survivorship (p-value 0.242 to 0.989)." The average HOOS was 85 ± 14.3 (range 30.6-100). Overall, 23 patients (48%) reported excellent HOOS scores (>90 points), 21 patients (44%) reported acceptable HOOS scores (60-90 points) while 4 patients (8%) reported poor outcomes (<60 points). Twenty-one patients (43%) were regularly involved into moderate- to high-intensity sport activities (UCLA ≥ 6). Conclusions: Cementless CoC THR is a successful procedure in children and teenagers, having demonstrated high implant survivorship and low rates of complications and failure. A meticulous preoperative planning and implant selection is mandatory, to avoid implant malposition, which is the main reason of failure and revision in these cases. Further studies are needed to assess the impact of the THR on the psychosocial wellbeing of teenagers, as well as risks and benefits and cost-effectiveness in comparison to the hip preserving surgical procedures.

Review of total hip arthroplasty in patients younger than 30 years: mid- to long-term results

BACKGROUND

Data on the outcome of THA in patients under the age of 30 years is sparse. There is a perceived reluctance to offer surgery to young patients on the basis of potential early failure of the implant. The aim of this study was to review clinical and radiological outcomes of THA in patients under the age of 30 years in a high-volume specialist arthroplasty unit.

METHODS

A retrospective review of patients between 1989 and 2009 was undertaken. 95 patients (118 THAs) were identified but 17 patients were excluded for lack of clinical records or for follow-up under 5 years. Clinical records were reviewed for demographics, underlying pathology, details of operation and failures. Radiographs were reviewed for evidence of loosening and wear of the components. Functional assessment was carried out using the modified Hip disability and Osteoarthritis Outcome Score, Oxford Hip Score and EQ-5D-5L.

RESULTS

Mean age was 25 (16-30) years and 65% patients were females. The most common underlying pathologies were development dysplasia of the hip (29%) and juvenile rheumatoid arthritis (25%). Mean follow-up was 12.6 (5-24) years, during which 19 patients (25%) were revised. The majority of the revisions were for aseptic loosening of the acetabular component.

CONCLUSIONS

Surgeons are cautious when considering THA in very young patients despite the significant documented improvement in function and quality of life after THA. This study reports on the mid- to long-term results of THA which will be valuable when advising young patients on the prospects of revision surgery at the time of primary THA.

Revision rate of THA in patients younger than 40 years depends on primary diagnosis - a retrospective analysis with a minimum follow-up of 10 years

Background

Treating osteoarthritis in elderly patients with THA is very successful. However, surgeons hesitate to recommend THA in younger patients. The spectrum of etiologies for end stage hip disease in the younger population is diverse and therefore different courses may be assumed. Our objective was to evaluate THA revision rate within a minimum follow-up period of 10 years in young patients and to analyze the difference between different primary diagnoses.

Methods

We included 144 consecutive hips in 127 patients younger than 40 years, who received a primary THA from 01/1996 to 12/2007. Operative reports, clinical and radiographic documentation were reviewed to determine primary diagnosis, prior hip surgery, component specifications and revision surgery. 111 hips in 97 patients were available for outcome analysis with a minimum follow-up of 10 years.

Results

The mean age was 33 years (range 15–40 years) at the time of the index THA, 68 patients were female and 59 were male. Ten years revision rate on the prosthetic components was 13%. The most common primary diagnosis was DDH. DDH was associated with a risk of 17% for requiring a reoperation on the prosthetic components because of mechanical fatigue and therefore, significantly higher than for any other primary diagnosis (p = 0.005).

Conclusion

THA in young patients is associated with a high revision rate of 13% in 10 years. 17% of patients with DDH required revision surgery for mechanical fatigue within 10 years, which was significantly higher than for any other primary diagnosis (1.2%, OR 16.8).

Total hip arthroplasty in patients with slipped capital femoral epiphysis: a systematic analysis of 915 cases

There is limited evidence on the outcomes of Total Hip Arthroplasty (THA) in Slipped Capital Femoral Epiphysis (SCFE) patients. This systematic review aims to evaluate the current literature in terms of survival rate, functional outcomes, complications and types of implants of THA in SCFE patients. Following the established methodology of PRISMA guidelines, PubMed, Cochrane library, ScienceDirect and Ovid MEDLINE were systematically searched from inception to September 2018. The search criteria used were: (“total hip arthroplasty’’ OR ‘’total hip replacement’’ OR “hip arthroplasty’’ OR ‘’hip replacement’’) AND (‘’slipped capital femoral epiphysis’’ OR ‘’slipped upper femoral epiphysis’’ OR ‘’femoral epiphysis’’). Ten studies were finally included in the analysis and were qualitatively appraised using the Newcastle-Ottawa tool. Variables were reported differently between studies. The sample size varied from 12 to 374 THAs. A total of 877 patients undergone 915 THAs. The mean reported follow-up ranged from 4.4 to 15.2 years and the mean patients’ age at the time of THA from 26 to 50 years. Four studies specified the type of implants used, with 62% being uncemented, 24% hybrid (uncemented cup/cemented stem) and 14% cemented. All but three studies reported the mean survival of implants that ranged from 64.9% to 94.8%. A limited number of complications were mentioned. There was a tendency for more favorable functional outcomes in modern studies. Modern THA-studies in SCFE patients showed improvement of survivorship, clinical outcomes and patient satisfaction. Future higher-quality studies are necessary to estimate long-term postoperative outcomes better.

Early to medium-term outcomes of uncemented ceramic-bearing total hip arthroplasty in teenagers for paediatric hip conditions

AIMS

Despite advances in the treatment of paediatric hip disease, adolescent and young adult patients can develop early onset end-stage osteoarthritis. The aims of this study were to address the indications and medium-term outcomes for total hip arthroplasty (THA) with ceramic bearings for teenage patients.

METHODS

Surgery was performed by a single surgeon working in the paediatric orthopaedic unit of a tertiary referral hospital. Databases were interrogated from 2003 to 2017 for all teenage patients undergoing THA with a minimum 2.3 year follow-up. Data capture included patient demographics, the underlying hip pathology, number of previous surgeries, and THA prostheses used. Institutional ethical approval was granted to contact patients for prospective clinical outcomes and obtain up-to-date radiographs. In total, 60 primary hips were implanted in 51 patients (35 female, 16 male) with nine bilateral cases. The mean age was 16.7 years (12 to 19) and mean follow-up was 9.3 years (2.3 to 16.8).

RESULTS

The most common indication for teenage hip arthroplasty was avascular necrosis secondary to slipped upper femoral epiphysis (31%; n = 16). Overall, 64% of patients (n = 33) had undergone multiple previous operations. The survival at follow-up was 97%; two patients required revision for aseptic loosening (one femoral stem, one acetabular component). Both patients had fused hips noted at the time of arthroplasty. A further two patients had radiolucent lines but were asymptomatic. At latest follow-up the mean Oxford Hip Score was 44 (31 to 48) and a Visual Analogue Scale measurement of 1.5, indicating satisfactory function.

CONCLUSION

Operating on this cohort can be complicated by multiple previous surgeries and distorted anatomy, which in some cases require custom-made prostheses. We have demonstrated a good outcome with low revision rate in this complex group of patients. Cite this article: Bone Joint J 2020;102-B(11):1491-1496.

A Comparison Study of the Outcomes of Ceramic-on-Ceramic Total Hip Arthroplasty in Young vs Older Patients: A Minimum 10-Year Follow-Up Prospective Matched Study

BACKGROUND

The purpose of this study is to analyze the outcome and prosthesis survival in patients aged between 20 and 40 years who received a cementless total hip arthroplasty (THA) with a minimum follow-up of 10 years compared to older patients.

METHODS

Prospective matched comparative study was conducted between 94 young patients with mean age of 37.2 (range 22-40) years and 90 older patients with mean age of 64.7 (range 60-70) years treated with ceramic-on-ceramic THA. Clinical outcomes were assessed by the Harris Hip Score, reduced Western Ontario and MacMaster University (WOMAC), and Short-Form-12 (SF12) questionnaires. Radiological evaluation was also performed. The primary outcome was the THA survival rate.

RESULTS

Mean follow-up of 13.6 (range, 10-15) years. At the final follow-up, there was no significant difference between groups in Harris Hip Score (P = .356), WOMAC-pain (P = .461), SF12-physical (P = .305), or SF12-mental (P = .511), but younger group had significantly higher WOMAC-function score (P = .013). There were 7 revisions in the younger group and 4 in the older group (P = .197). The 14-year prosthesis survival for any reason was 93.2% (95% confidence interval [CI] 86.7-99.7) in the younger group and 98.3% (95% CI 95.1-100) in the older group (P = .189). For aseptic reason, the 14-year survival was 94.7% (95% CI 88.9-100) in the younger group and 98.3% (95% CI 95.1-100) in the older group (P = .332).

CONCLUSION

At minimum follow-up of 10 years, THA with cementless stem and ceramic-on-ceramic bearing provides successful survival and functional outcomes in young patients between 20 and 40 years old.

The evolution of an uncemented acetabular component in alumina-on-alumina total hip arthroplasty has improved clinical outcome

Aims

To determine the effect of a change in design of a cementless ceramic acetabular component in fixation and clinical outcome after total hip arthroplasty

Patients and Methods

We compared 342 hips (302 patients) operated between 1999 and 2005 with a relatively smooth hydroxyapatite coated acetabular component (group 1), and 337 hips (310 patients) operated between 2006 and 2011 using a similar acetabular component with a macrotexture on the entire outer surface of the component (group 2). The mean age of the patients was 53.5 (14 to 70) in group 1 and 53.0 (15 to 70) in group 2. The mean follow-up was 12.7 years (10 to 17) for group 1 and 7.2 years (4 to 10) for group 2.

Results

No hips were revised due to complications related to bearing fracture or to stem loosening. A total of 15 acetabular components were revised for aseptic loosening in group 1 and two in group 2. The survival rate for acetabular component aseptic loosening at eight years was 96.8% (95% confidence interval (CI) 94.8 to 98.7) for group 1 and 99.2% (95% CI 98.0 to 100) for group 2. The risk for aseptic loosening of the acetabular component was higher in group 1 (p = 0.04, Hazard Ratio (HR) 4.99), dysplastic acetabula (p = 0.01, HR 4.12), components outside Lewinnek´s zone (p < 0.001, HR 6.13) and in those with a hip rotation centre distance greater than 5 mm (p = 0.005, HR 4.09).

Conclusion

Alumina ceramic-on-ceramic THA is an excellent option for young patients. Although newer components appeared to improve fixation, acetabular reconstruction is essential to obtain a satisfactory outcome. Cite this article: Bone Joint J 2017;99-B:749–58.

Hard-on-Hard Bearings Are Associated With Increased Noise Generation in Young Patients Undergoing Hip Arthroplasty

BACKGROUND

Patient-perceived noise from prostheses after total hip arthroplasty (THA) does occur, yet questions remain including the overall frequency of this finding, demographic and prosthesis-related factors, and the association of noise generation with patient-reported outcomes.

QUESTIONS/PURPOSES

The purposes of this study were (1) to determine the frequency with which patients report noise coming from the hip after THA; (2) to identify patient and prosthesis-related factors associated with noise generation; and (3) to ascertain if noise generation is associated with pain or functional impairment after THA.

METHODS

A five-center study was designed to quantify the degree of residual symptoms and functional deficits in patients undergoing THA. Three centers were academic practices, whereas two centers were private practices that provided training programs for orthopaedic residents and fellows. Each contributing surgeon was fellowship-trained and specialized in joint replacement. Inclusion criteria for this study were (1) men between 18 and 60 years old and women between 18 and 55 years old; (2) patients requiring primary hip surgery as a result of noninflammatory arthritis such as osteoarthritis, traumatic arthritis, or avascular necrosis; (3) a UCLA activity score of 6 or more before they were limited by pain; and (4) patients who had undergone a primary THA within 1 to 4 years before the start of the study and had a minimum of 1 year of clinical followup. Attempts were made to contact all identified patients meeting these inclusion criteria. Data were collected by an independent, third-party survey center blinded to the implant design and bearing surface used who administered questionnaires about residual symptoms, function, and pre- and postoperative activity levels using previously published survey instruments. Patients were specifically queried regarding perceived noise from their THA. We retrospectively identified 1242 eligible patients. Of the 1242 patients, 105 were found to have exclusions during the screening section of the questionnaire: postoperative infection (six THAs), fracture (two), dislocation (seven), or revision (17); limited activity level because of an operation on the opposite hip (34); and premorbid UCLA score of less than 6 (39). In addition, 128 individuals refused to participate, 156 were never available, 108 were not found as a result of a bad address/phone number, 48 were contacted but did not complete the interview, nine had died, and six had a language barrier. This left 682 of the 1137 eligible patients with completed surveys (60% response rate). The mean age was 50 ± 8 years at the time of surgery with 63% being men, and they were contacted at a mean of 3 ± 1 years postoperatively. Bearing surfaces (femoral head-acetabular liner) included 210 (31%) metal-on-metal, 144 (21%) ceramic-on-ceramic, 142 (21%) ceramic-on-polyethylene, 141 (21%) cobalt-chromium-on-polyethylene, and 44 (6%) oxidized zirconium-on-polyethylene. Differences in baseline demographic variables were accounted for using multiple logistic regression statistical analyses. Pearson's correlation coefficients were used to determine the association of noise generation with residual symptoms.

RESULTS

Overall, 9% (61 of 682; 95% confidence interval [CI], 7-11) of young patients undergoing primary THA reported noise generation. Females (12% [30 of 251 patients]) were noted to have an increased likelihood of reporting noise versus males (7% [30 of 431 patients]; odds ratio, 1.8; 95% CI, 1.1-3.1; p = 0.03). After controlling for potential confounding variables including female sex and length of followup, patients receiving a ceramic-on-ceramic or metal-on-metal bearing surface (14% [50 of 355]) reported an increased frequency of grinding, popping, and clicking in the 30 days before survey administration versus those receiving a polyethylene liner with a ceramic, oxidized zirconium, or cobalt-chromium femoral head (3% [10 of 327 patients]; odds ratio, 5.6; 95% CI, 2.7-11.5; p < 0.001). Noise generation was associated with increased pain (r = 0.23, p < 0.001) and stiffness (r = 0.22, p < 0.001) after THA.

CONCLUSIONS

When interviewed by an independent third party, patients receiving a metal-on-metal or ceramic-on-ceramic bearing reported a higher frequency of noise generation versus patients receiving a polyethylene liner after THA. Young patients undergoing THA should be counseled that noise generation could be associated with increased pain after THA.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Ceramic-on-ceramic bearings total hip arthroplasty in young patients

Background

The results of ceramic-on-ceramic (CoC) total hip arthroplasty (THA) in younger patients were not univocal. This study aims to evaluate the results of CoC bearing THA in patients younger than 50 years.

Methods

A total of 90 younger patients performed CoC THAs during March 2003 and May 2008 were included in this study. Hip function and activity were evaluated with Harris hip score and University of California Los Angeles activity score. We had discussed survival rates, radiological findings of component loosening or osteolysis, and ceramic-related complications in these patients.

Results

The mean Harris hip score increased from 46.3 ± 12.0 points (range, 28-70 points) before surgery to 92.5 ± 5.6 points (range, 78-100 points) at the final follow-up. The mean preoperative University of California Los Angeles activity score was 4.2 ± 1.1 points (range, 2-6 points), which improved to a mean of 7.2 ± 1.3 points (range, 4-10 points). At the time of the last follow-up, there was found to be 1 occurrence of hip dislocation, 1 squeaking, and 2 “sandwich” ceramic liners fractured during normal activity of daily living. No hips showed osteolysis or required revision for aseptic loosening. Kaplan-Meier survivorship with revision due to loosening or osteolysis was 100% and with revision due to ceramic fracture was 97.3% (95% confidence interval, 93.7%-100%) at a mean of 9.4 years.

Conclusions

This study with the use of CoC bearings THAs in younger patients have shown promising results and higher rate of survivorship without evidence of osteolysis.

Wear products of total hip arthroplasty: The case of polyethylene

Among the bearing surfaces involved in a total hip arthroplasty, ultra-high molecular weight polyethylene (UHMWPE) is the weak link. It is submitted to the friction of a harder bearing, producing wear particles, which, in turn, initiate an inflammatory reaction ultimately leading to osteolysis. This kind of bone deterioration sometimes turns out to an aggressive granuloma and may provoke implant loosening. Wear resistance of UHMWPE depends on its molecular weight and crystallinity. Some steps of the manufacturing process were improved to optimize its tribological properties and to slow down degradation resulting from mechanical (abrasion) and chemical (oxidation) phenomena. Its preparation and conservation must be performed in an inert atmosphere, i.e. without ambient oxygen. Its resistance to abrasion depends on its cross-linking degree. Its cross-linking rate was observed to increase proportionally to the irradiation doses, improving its wear resistance. However, its mechanical properties are impaired and moreover, it becomes oxidation sensitive. It is therefore necessary to submit it to a thermal treatment to eliminate free radicals that were produced during irradiation. More recently impregnation by vitamin E, a powerful anti-oxidant product, was proposed to preserve the polymer from in vivo oxidation while maintaining its mechanical properties. We raised the hypothesis that last-generation UHMWPE could offer the same wear resistance as the most performing bearings (ceramic-on-ceramic). Recent clinical results confirm the tribological performance of highly crosslinked UHMWPE in vivo. However, it remains to be seen whether this excellent wear resistance would persist under eccentric load such as edge loading, and if, in the long run, this kind of bearing proves capable of reducing the risk of osteolysis in young and active patients.

Ceramic-on-ceramic THA Implants in Patients Younger Than 20 Years

BACKGROUND

Poor survival of THA implants in very young patients has been attributed to use of cemented implants, wear of conventional polyethylene, and the presence of morphologic deformities in the proximal femur or in the acetabulum. Few studies have reported the long-term results of ceramic-on-ceramic implants in THAs in patients younger than 20 years.

QUESTION/PURPOSES

We determined: (1) the proportion of patients who experienced complications related to the ceramic bearing (squeaking, fracture); (2) the survivorship free from loosening and free from revision for any reason; (3) whether patients with osteonecrosis had inferior survivorship compared with patients whose surgical indication was all other diagnoses including sequelae of pediatric hip disorders (developmental dysplasia of the hip, Legg-Calvé-Perthes disease, slipped capital femoral epiphysis); and (4) clinical function.

METHODS

Between 1979 and 2013, we performed 113 primary THAs in 91 patients younger than 20 years at the time of surgery. Of those, 105 THAs (83 patients) were done with ceramic-on-ceramic bearings (91% of the 91 patients); during that period, a ceramic-on-ceramic bearing couple was indicated in all patients younger than 20 years. In eight patients (eight hips), a cemented polyethylene cup was implanted because the diameter of the acetabulum was smaller than the smallest available ceramic cup (46 mm), or because adequate fixation of a ceramic press-fit cup could not be achieved despite careful reaming of the acetabulum. The most common diagnosis indicating THA was avascular necrosis of the femoral head (56.2%; 59 hips). Thirty-five patients (40 hips) had undergone previous operations before the replacement. Three patients (4%; four hips) died from unrelated causes, nine patients (11%; 13 hips) were lost to followup, and four patients (five hips) had a followup greater than 8.5 years but have not been seen in the last 5 years. Patients were assessed clinically (using the Merle d'Aubigne-Postel score, Hip disability and Osteoarthritis Outcome score (HOOS), and the SF-12(®) Health Survey, and radiographically for signs of radiolucencies, subsidence, or osteolysis on plain films. The mean followup was 8.8 ± 6.1 years (range, 2-34.4 years).

RESULTS

Five patients experienced transient noise generation, defined as a snap in four patients and squeaking in one. Seventeen hips underwent revision surgery-16 for aseptic loosening and one for septic loosening. The implant survival rate at 10 years with aseptic loosening as the endpoint was 90.3% (95% CI, 82.4%-98.9%). No hip had acetabular or femoral osteolysis. Survivorship in patients with osteonecrosis did not differ from survivorship in patients with other diagnoses. The Merle d'Aubigne-Postel score increased from 10.1 ± 4.0 to 17.6 ± 1.1 (p < 0.01); the mean HOOS score was 79.3 ± 13.8 (range, 50.6-100); the mean SF-12(®) physical and mental component scores were 48.1 ± 7.9 (range, 21.4-57.6), and 47.4 ± 12.2 (range, 24.5-99.4), respectively.

CONCLUSIONS

We found that patient-reported outcomes scores improved in most patients undergoing THA in this very young study group. Underlying diagnosis did not affect long-term survivorship. However, the revision-free survival rate at 10 years is lower than published estimates in older patients, and with 11% of patients lost to followup, our estimates may represent a best-case scenario. Therefore, we believe THA should be performed as a last resort in this population.

LEVEL OF EVIDENCE

Level IV, therapeutic study.

Activity levels and functional outcomes of young patients undergoing total hip arthroplasty

The activity demands of young patients undergoing total hip arthroplasty (THA) have not been clearly defined. University of California Los Angeles (UCLA) activity score, Hip disability and Osteoarthritis Outcome Score (HOOS), Short Form-12 version 2 (SF-12v2), and Functional Comorbidity Index (FCI) questionnaires were administered to 70 young patients who had undergone THA (young THA group; ie, ≤30 years old), 158 general patients who had undergone THA (general THA group; ie, ≥31 years old), and 106 young, comorbidity-matched patients who had not undergone arthroplasty and had no significant hip disease (nonarthroplasty group). Mean postoperative UCLA activity scores were similar among groups (young THA group, 6.5; general THA group, 6.4; nonarthroplasty group, 6.6) before and after adjustment for comorbidity, sex, and race (P=.62 and P=.47, respectively). Adjusted analyses also found a negative association between postoperative activity and increases in comorbidity and female sex (P<.001). Patients in the young THA group reported higher expectations of postoperative activity (7.7) than those in the general THA group (7.1; P=.02). Postoperative HOOS results showed greater hip symptoms (P=.003) and poorer hip-related quality of life (P<.001) in the young THA group. Patient groups had similar postoperative SF-12v2 physical health scores (P=.31), although mental health scores were significantly higher in the general THA group (P<.001). The interesting finding of lower postoperative expectations, greater hip-related quality of life, and better mental health scores in the general THA group may indicate a need for better management of expectations in young patients undergoing THA, including a discussion of realistic gains in activity and potential comorbidity-related restrictions.

Study of the polycarbonate-urethane/metal contact in different positions during gait cycle

Nowadays, a growing number of young and more active patients receive hip replacement. More strenuous activities in such patients involve higher friction and wear rates, with friction on the bearing surface being crucial to ensure arthroplasty survival in the long term. Over the last years, the polycarbonate-urethane has offered a feasible alternative to conventional bearings. A finite element model of a healthy hip joint was developed and adjusted to three gait phases (heel strike, mid-stance, and toe-off), serving as a benchmark for the assessment of the results of joint replacement model. Three equivalent models were made with the polycarbonate-urethane Tribofit system implanted, one for each of the three gait phases, after reproducing a virtual surgery over the respective healthy models. Standard body-weight loads were considered: 230% body-weight toe-off, 275% body-weight mid-stance, and 350% body-weight heel strike. Contact pressures were obtained for the different models. When comparing the results corresponding to the healthy model to polycarbonate-urethane joint, contact areas are similar and so contact pressures are within a narrower value range. In conclusion, polycarbonate-urethane characteristics are similar to those of the joint cartilage. So, it is a favorable alternative to traditional bearing surfaces in total hip arthroplasty, especially in young patients.

Alumina-on-alumina hip replacement in developmental dysplasia of the hip

Total hip arthroplasty (THA) in patients with developmental dysplasia of the hip (DDH) requires complex reconstructive techniques and presents an increased risk of complications. Because of these patients' young age, alternative bearing surfaces such as alumina-on-alumina couples could be an option. We asked whether moderate or severe congenital dysplasia of the hip would influence the clinical outcome and rates of cup loosening in our patients. We prospectively compared 50 hips in patients with dysplastic hip (group 1) and 22 hips in patients with a low or high dislocation (group 2) using an alumina-on-alumina THA. The minimum follow-up was 5 years (range 5-10 years). Age, activity level, and implant size were greater in group 1. Preoperative function and range of mobility were worse in group 2. The survival rate for cup loosening at 5 years was 89.8% (95% confidence interval, 78.7%-100%) for group 1 and 81.7% (95% confidence interval, 57.6%-100%) for group 2. An alumina-on-alumina THA provides a high level of pain relief and functional improvement in hip dysplasia. Continued follow-up will be required to determine if the alumina-on-alumina bearings in these patients result in less osteolysis and loosening.

Evora® chromium-cobalt dual mobility socket: results at a minimum 10 years' follow-up

INTRODUCTION

The Evora chromium-cobalt alloy dual mobility socket claims to display a large articulation tribology different from that of stainless steel models, limiting the risk of intraprosthetic dislocation and wear. The present study reports a minimum of 10years' follow-up in a multicenter prospective series of 200 sockets previously reported on at 5years.

HYPOTHESIS

The use of chromium-cobalt in dual mobility sockets provides a low rate of failure at 10years, especially as regards to osteolysis and intraprosthetic dislocation.

MATERIALS AND METHODS

Two hundred hydroxyapatite-coated molded chromium-cobalt sockets without titanium interface were implanted without cement in 194 patients with a mean age of 70 years (range, 32-91 years). Clinical results were assessed on Postel Merle d'Aubigné and Harris scores, plain radiographs and survival analysis.

RESULTS

At a mean 11 years' follow-up (10-13 years), 56 patients had died and 31 were lost to follow-up. Four underwent surgical revision (3 femoral components, and 1 socket for migration at 9 years with complete disappearance of the hydroxyapatite). A total of 109 implants were analyzable in 107 patients with a mean age of 81 years (55-93 years). At follow-up, the mean Harris score was 90 (75-96) and the PMA score 16.3 (14-18). There were no cases of loosening (except for the case reoperated on at 9 years) and no acetabular radiolucency or cysts. There were 2 cases of non-evolutive femoral radiolucency and 10 of femoral granuloma, involving head size > 22 mm (P<0.0001) and a cemented titanium stem (P=0.004) as risk factors. There were no dislocations in the large or small articulation. Ten-year survival was 99% (95% CI: 97.3%-100%) with socket revision as censorship criterion.

DISCUSSION

The absence of dislocation in both small and large articulations confirmed the efficacy of the dual mobility concept and suggested an advantage for chromium-cobalt sockets in reducing the rate of intraprosthetic dislocation and preventing blockage of the large articulation by a better performance in the friction couple. Granulomas were associated with wear in cemented titanium stems and with heads greater than 22 mm in diameter. Ten-year survival was 99% (censorship criterion: revision for socket failure); there was, however, one case of socket loosening with disappearance of the hydroxyapatite, indicating that surveillance should be continued in this cohort.

Failure analysis of alumina on alumina total hip arthroplasty with a layered acetabular component: minimum ten-year follow-up study

This prospective study reports the outcome of total hip arthroplasty (THA) performed in a consecutive series of patients using an alumina ceramic on a ceramic-layered component (Alumina-Bearing-Surface system). The cohort consisted of 270 hips in 229 patients. The study evaluated the clinical and radiological results over a mean follow-up of 11.4 years. Revision THA was performed on 58 hips, including alumina alternative failure in 50 hips, loosening in 4 hips, recurrent dislocation in 2 hips, stem neck fracture in 1 hip and hematoma in 1 hip. The survival rate was 68% with revision for any reason as the end point. The risk factors of implant failure are the preoperative range of motion of the hip joint and postoperative dislocation.

Mean 5-year clinical and radiographic outcomes of cementless total hip arthroplasty in patients under the age of 30

We performed a retrospective review of 40 consecutive modern cementless THAs with 65-month mean followup in 34 patients under the age of 30 primarily for diagnoses other than inflammatory arthritis. We found acceptable functional improvement and radiographic outcomes at mean 5-year followup. We found a high transfusion rate, dislocation rate (10%), and midterm overall aseptic revision rate (17%). Twenty-eight (67.5%) of hips in this series were metal on metal, with a large percentage of aseptic revisions related to metallosis (57%). When revisions due to metallosis were excluded, the aseptic revision rate was 7.5%. The high prevalence of prior pediatric hip surgery in these patients (50%) may predispose to increased technical difficulty resulting in increased complications and higher revision rates. Although our revision rate was high in these young patients, it is favorable compared to older techniques and consistent with the limited data available with modern cementless techniques in patients of similar age. Cementless THA with modern designs remains a viable option for the treatment of arthritis in the young patient.

Total hip arthroplasty in teenagers: an alternative to hip arthrodesis

Debilitating arthritis in teenage patients is a complex problem with limited surgical options. Hip arthrodesis is unpopular amongst patients, and contemporary total hip arthroplasty (THA) may be a promising alternative. We report on the outcomes of THA in patients less than 20 years of age. All consecutive teenage patients undergoing THA at a tertiary referral centre were reviewed. Mean follow-up was 3.4 years (range 0.6-6.8) and 9 patients had at least 5 years follow-up. There were 51 THAs in 43 patients with a mean age of 17 years (range 12-19). The commonest indication was osteonecrosis (35 cases), mostly secondary to slipped upper femoral epiphysis (15 cases). Forty-six were uncemented and 5 were reverse hybrid THAs of which 7 were computer assisted design/manufacture (CADCAM) components. The commonest bearing surface used was ceramic on ceramic (40 cases). The survival rate was 96% and there were 2 complications. At latest follow-up, the mean Harris hip score was 90 (range 68-99) and UCLA activity score was 6 (range 4-9). Radiological analysis showed 2 patients with lucent lines around the acetabular component, but no signs of osteolysis or wear. We report good short to intermediate term survivorship and outcomes, and feel THA represents a valid alternative option to hip arthrodesis.

Eleven year results of total hip arthroplasty in patients with secondary osteoarthritis due to slipped capital femoral epiphysis

Background:

Total hip arthroplasty (THA) in patients with a history of Slipped Capital Femoral Epiphysis (SCFE), is typically indicated to address the consequent deformity of the proximal femur and/or acetabulum. It can be a challenging procedure for the orthopaedic surgeon. Previous studies have focused on prevention of osteoarthritis post-SCFE. However, there is a paucity of data on the outcomes of total hip arthroplasty in patients with osteoarthritis secondary to SCFE. This study was performed to assess the mid-term results of total hip arthroplasty in this patient cohort.

Materials and Methods:

All patients with secondary osteoarthritis due to slipped capital femoral epiphysis, treated with total hip arthroplasty between 1987 and 2005, were included in this retrospective study (n=30). Thirty patients (17 male, 13 female) met the inclusion criteria with one patient lost to follow-up and one unrelated death one year before follow up examination, thereby leaving 28 patients (32 hips) eligible for the study with a mean follow-up time period of 11.2 years. The Harris Hip Score (HHS) and MOS 36 short form health survey (SF36) were determined preoperatively and at most recent follow-up for all patients. Complications were also noted for all cases.

Results:

The mean Harris Hip Score increased significantly from 47 (32-59; SD=8.3) to 92.3 (65-100; SD=8.2) (p<0.0001). The SF-36 health survey showed an improvement of quality-of-life in all sub-scales. Overall, revision surgery was required in six cases (19 %). Aseptic loosening, leading to implant removal, was noted in five cases. A single-stage revision to address infection was performed in one case. The cumulative survival rate at latest follow-up was 81 %. No other complications were encountered during the study.

Conclusions:

Despite a higher failure rate, compared to total hip arthroplasty in the treatment of primary osteoarthritis, total hip arthroplasty can be considered a feasible option for patients with secondary osteoarthritis of the hip due to slipped capital femoral epiphysis. The current study demonstrates good outcomes in patients treated with a cementless column-preserving prosthesis, which is of particular relevance for this young patient cohort. However, further clinical prospective randomized studies are warranted to provide more definitive evidence.

Long-term results of cemented total hip arthroplasty in patients younger than 30 years and the outcome of subsequent revisions

BACKGROUND

The number of total hip arthroplasties in patients under 30 years is increasing over the years. Almost all of them will face at least one or more future revisions in their life. Therefore, the implant used should have a high survival rate, and needs to be easily revisable resulting in a low re-revision rate. Several studies have evaluated the outcome of total hip arthroplasties in patients under 30 years. However, only a few reported on the follow-up outcome of 10 years or more. In addition, none of these reports published data of the subsequent revisions of these implants within their original report.

METHODS

We studied historically prospective collected data of 48 consecutive patients (69 hips) younger than 30 years, treated with a cemented primary total hip prosthesis between 1988 and 2004. Since the last evaluation of this cohort, two patients were lost to follow-up. For all hip revisions in this cohort, again cemented implants were used, mostly in combination with bone impaction grafting. Kaplan-Meier survival curves at 10- and 15 years for the primary total hip arthroplasties and revisions were determined.

RESULTS

The mean age at time of primary surgery was 25 years (range, 16 to 29 years). Mean follow-up of the primary hips was 11.5 years (range, 7 to 23 years). During follow-up 13 revisions were performed; in 3 cases a two-stage total revision was performed for septic loosening and 9 cups were revised for aseptic loosening. There were no aseptic stem revisions. The 10 and 15-year survival rates with endpoint revision for aseptic loosening of the primary total hip were 90% (95% CI: 79 to 96) and 82% (95% CI: 65 to 92) respectively. None of our 13 subsequent revisions needed a re-revision within 10 years after re-implantation.

CONCLUSIONS

Cemented total hip implants in patients under 30 years have an encouraging outcome at 10 and 15 years after surgery in these young patients. The 13 revised hips, treated with bone grafting and the third generation cement technique, were performing well with no re-revisions within ten years after surgery.

Alumina-on-alumina THA performed in patients younger than 30 years: a 10-year minimum followup study

BACKGROUND

THA in patients younger than 30 years presents challenges because of uncertainties regarding the long-term survivorship of prostheses. Alumina-on-alumina bearings, which exhibit little long-term wear, may be a reasonable option but the long-term survivorship is unknown.

QUESTIONS/PURPOSES

We determined (1) the survival rate of alumina-on-alumina bearings in patients younger than 30 years after a 10-year followup, (2) the incidence of audible hip clicking and squeaking, (3) radiographic evidence of osteolysis, and (4) the effects on pregnancy, childbirth, and career choice.

METHODS

We retrospectively reviewed 62 patients who had 75 THAs with alumina-on-alumina bearings followed more than 10 years (average, 11.5; range, 10-13.5 years). Mean patient age at the time of surgery was 24 years (range, 18-30 years). All operations were performed using the same cementless implant at a single center. We determined survival, presence of osteolysis, and function (Harris hip score, WOMAC).

RESULTS

The 10-year survival rate of alumina-on-alumina bearings in THAs, with revision for any reason as the end point, was 98.9%. Audible hip clicking and squeaking were identified in 10 hips and two hips, respectively. No osteolysis was detected. None of the 11 patients who became pregnant had been affected by their THA during pregnancy or childbirth. Seven of the 14 patients who were unemployed at the time of index surgery stated that their THA affected their job choice.

CONCLUSIONS

We found a high 10-year survival of cementless alumina-on-alumina bearings in THAs in patients younger than 30 years. Lifetime events such as job choice, pregnancy, and childbirth should be considered when choosing THA for patients younger than 30 years.

LEVEL OF EVIDENCE

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

Third-generation ceramic-on-ceramic total hip arthroplasty in patients younger than 30 years with osteonecrosis of femoral head

The purpose of this study was to evaluate the functional and radiographic results of patients younger than 30 years who underwent cementless third-generation ceramic-on-ceramic total hip arthroplasty for osteonecrosis of the femoral head. Forty-one patients (56 hips) with a minimum follow-up of 6 years were included. In all cases, third-generation ceramic-on-ceramic articulation was used. Average Harris Hip Scores improved from 52.9 preoperatively to 98.2, and Western Ontario and McMaster Universities Osteoarthritis Index score, from 95.2 to 25.2. Thirty-nine patients returned to their normal occupations. No aseptic loosening or osteolysis was observed. Total hip arthroplasty performed using third-generation ceramic-on-ceramic bearings for osteonecrosis of femoral head was found to provide satisfactory clinical and radiologic results, especially in active, young patients.

Hip resurfacing in patients under thirty years old: an attractive option for young and active patients

PURPOSE

Metal-on-metal hip resurfacing is offered as an alternative to traditional hip arthroplasty for young, active adults with advanced osteoarthritis. The concept of hip resurfacing is considered very attractive for this specific population (hard-on-hard bearing component with a large femoral head limiting the risk of dislocation, and allowing femoral bone stock preservation).

METHODS

A prospective clinical trial was designed to investigate the outcome of hip resurfacing in young patients (under 30 years old). We studied 24 hips in 22 patients. Mean age at operation was 24.9 years (range 17.1-29.9). No patient was lost to follow-up.

RESULTS

There was no revision at average follow-up of 50.6 months (44-59). Mean UCLA activity score improved from 5.5 (1-9) pre-operatively to 7.6 (1-10) postoperatively (p < 0.001). Mean Harris hip score increased from 43.9 (19-67) to 89.3 (55-100) (p < 0.001). Radiological analysis discerned no osteolysis and no implant migration.

CONCLUSION

The absence of short-term complications, such as mechanical failure or dislocation, is encouraging and leads us to think that mid-term results will be satisfactory. Moreover, the specific advantages of hip resurfacing (bone stock preservation, excellent stability, low risk of dislocation, large-diameter head) make the procedure a very attractive option for young subjects.

Alumina-on-alumina THA in patients with juvenile idiopathic arthritis: a 5-year followup study

BACKGROUND

THA is a concern in juvenile idiopathic arthritis (JIA) owing to patients' youth, poor bone stock, and small physical size.

QUESTIONS/PURPOSES

We asked whether (1) uncemented alumina-on-alumina THAs have good clinical and radiographic results at midterm followup in young patients with inflammatory arthritis and end-stage hip disease secondary to JIA, and (2) the anatomic center of rotation of the hip could be reconstructed in patients with acetabular protrusion. We also assessed the rate of surgical complications.

PATIENTS AND METHODS

We retrospectively reviewed 31 alumina-on-alumina THAs in 21 patients with a mean age of 30.9 years (range, 14-48 years). Minimum followup until the time of revision of any component or the latest evaluation was 16 months. For nonrevised cases, the minimum followup was 60 months (range, 60-108 months). Acetabular protrusion was mild in 17 hips (Group 1) and moderate-severe in 14 (Group 2). Bone autograft was used to reconstruct the acetabulum in Group 2. Acetabular reconstruction was evaluated according to Ranawat et al.

RESULTS

One cup was revised owing to aseptic loosening at 16 months; the remaining hips showed good clinical and radiographic results. The mean postoperative horizontal distance and the distance between the center of the head of the prosthesis and the true center of the femoral head improved in Group 2. There were no complications related to alumina.

CONCLUSIONS

Although THA is a technically demanding procedure in patients with JIA, uncemented alumina-on-alumina THA provides pain relief and improves quality of life. In patients with acetabular protrusion, bone grafts enable anatomic cup positioning. Continued followup will be required to determine whether the alumina-on-alumina bearings in patients with JIA result in less osteolysis and loosening.

LEVEL OF EVIDENCE

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

Factors affecting modular acetabular ceramic liner insertion: a biomechanical analysis

BACKGROUND

Ceramic liner fracture is a concern in THA. However, it is unclear what factors influence the risk of facture. To study these factors under controlled conditions, we created a laboratory model to avoid fractures in vitro.

QUESTIONS/PURPOSES

We determined (1) whether misaligned liner insertion, acetabular shell deformation, entrapment of soft tissue within the locking taper area, and damage to the taper during engagement of the ceramic liner on the locking taper influenced fracture at light and medium impaction forces; and (2) whether the number and force of impactions affect the locking taper force between the ceramic liner and acetabular shell and fracture of the ceramic liner.

METHODS

Impaction and pushout tests were performed with each of five ceramic inserts in titanium shells per test to simulate clinical intraoperative situations of misaligned inserts (Test 1), deformed shells (Test 2), soft tissue within the locking taper area (Test 3), simulated cup taper damage (Test 4), and a combination of misaligned insert, deformed shells, and simulated taper damage to create an overall worst-case condition (Test 5).

RESULTS

Higher pushout forces occurred with increased impact force and an increased number of strikes. Insert fractures only occurred where inserts were misaligned in the shell. No fractures occurred with deformed shells, soft tissue in the taper, or with simulated taper damage in the absence of misaligned inserts.

CONCLUSION

The data suggest a misaligned ceramic insert in an acetabular increases the potential for insert fracture. Shell deformation, soft tissue in the taper, or simulated taper damage seemed well tolerated even with very forceful impaction. Forceful and repetitive impaction is favorable for engagement of the taper and improving pullout strength.

Ceramic-on-ceramic total hip arthroplasty in patients younger than 20 years

Total hip arthroplasty (THA) in the adolescent patient has historically shown relatively poor survivorship. This study reports the results of THA in young patients using contemporary ceramic bearings. Twenty-four THAs were performed using ceramic bearing surfaces in patients 20 years old or younger (mean, 16.4; range, 12-20). Average follow-up was 52 months (range, 25-123 months). The survival rate was 96%, with 1 revision for a loose acetabular component. Other complications included a peroneal nerve palsy that resolved and 2 dislocations in 1 patient. Postoperatively, the Modified Harris Hip Score mean was 93.4 (range, 66-100). This study shows promising results at short-term to midterm follow-up in very young patients who undergo THA using ceramic-on-ceramic components.

Excellent results with cementless total hip arthroplasty and alumina-on-alumina pairing: minimum ten-year follow-up

Ceramic-on-ceramic coupling is thought to be a durable alternative to metal- or alumina-on-polyethylene pairing. No evidence exists suggesting superior clinical and radiological results for hydroxyapatite-coated stems versus uncoated stems. The aim of this study is to report the performance of an alumina-on-alumina bearing cementless total hip arthroplasty and to compare stems with a tapered design with and without hydroxyapatite coating. We prospectively analysed the results of cementless tapered femoral stems (40 hydroxyapatite-coated versus 22 uncoated stems), a metal-backed fibre mesh hydroxyapatite-coated socket and alumina-on-alumina pairing. Of 75 hips studied, 62 were available for follow-up (mean of 10.5 years after surgery). The average Harris hip score was 90. Only one hydroxyapatite-coated stem was revised for aseptic loosening. One instance of non-progressive osteolysis was detected around a screw of a cup. All other components showed radiographic signs of stable ingrowth. Hydroxyapatite coating of the stem had no significant impact on the clinical or radiological results. Total hip arthroplasty with the presented implant and pairing provides a durable standard for all patients requiring hip joint replacement against which all newer generations of cementless implants should be judged.

Metal-on-metal hip arthroplasty in patients thirty years of age or younger

BACKGROUND

Total hip arthroplasty in patients younger than thirty years of age represents a long-term challenge. As polyethylene wear secondary to a high activity level could be problematic, hard-on-hard bearings have been proposed to reduce wear. The aim of this retrospective case series was to assess the clinical and radiographic results of primary metal-on-metal total hip arthroplasty in patients thirty years of age or younger.

METHODS

We retrospectively studied thirty-four patients (forty-seven hips) who had undergone metal-on-metal total hip arthroplasty and analyzed the radiographic and clinical measurements after a mean duration of follow-up of 108 months (range, 62.4 to 153.6 months). The mean age of the patients at the time of surgery was twenty-five years (range, fifteen to thirty years). The diameter of the head of the femoral component was 28 mm in all hips except five, in which it was 32 mm. The metal-on-metal bearing was the same in all patients.

RESULTS

The mean Merle d'Aubigné score increased from 10.6 (range, 1 to 14) to 17.1 (range, 12 to 18). No wear was found on the latest radiograph, but osteolysis was noted in three femora and two acetabula. Two revisions were performed, one because of impingement secondary to cup malorientation and the other because of acetabular loosening with osteolysis. Kaplan-Meier analysis with revision of either component as the end point revealed a ten-year survival rate of 94.5% (95% confidence interval, 80% to 98.6%). The survival rate of the femoral stem was 100%.

CONCLUSIONS

These encouraging intermediate-term results indicate that hip arthroplasty with metal-on-metal bearing components may be a suitable solution for young and active patients with hip osteoarthritis or osteonecrosis of the femoral head.

Is alumina-on-alumina ceramic bearings total hip replacement the right choice in patients younger than 50 years of age? A 7- to 15-year follow-up study

INTRODUCTION

The alumina-on-alumina bearing couple in total hip replacement seems to be well adapted for young and active patients because of the absence of wear and the rarity of osteolysis. Over the long term, doubts persist as to the cementless cup fixation and on the functioning of this bearing system because of possible acoustic emissions during use.

HYPOTHESIS

In young subjects, the ceramic-on-ceramic bearing system limits wear and osteolysis occurrences, without exposing patients to serious side effects. MATERIAL AND MEHTODS: We report the results, with between 7 and 15 years of follow-up, for 32mm-diameter alumina-on-alumina implants in 76 patients younger than 50 years of age (83 hips), combining cementless press-fit hemispheric cups with titanium stems, [either cemented (63 Osteal™ stems) or cementless (20 Multicône™ stems)], with particular attention paid to cup fixation and noise emissions during implant function. First-generation or Cerafit trellis™ acetabular components had a riveted titanium mesh (31 cases), whereas the most recent (Cerafit hydroxyapatite [HA]™) cups had a porous surface coated with hydroxyapatite (52 cases).

RESULTS

Three cases of aseptic loosening of the cemented stems were observed as well as late migration of a Cerafit trellis™ cup in the 12th postoperative year. One ceramic insert broke in the eighth postoperative year. With the exception of one case, the patients, questioned retrospectively, reported no audible noise. With aseptic loosening (revised or not), the criterion for failure, the 12-year survival rate was 91±11% for the Cerafit trellis™ acetabular components and 91±16% for the cemented Osteal™ stems. The 9- and 7-year survival rates for the Cerafit HA™ cups and the Multicône™ stems, respectively, were 100%. Including all revisions for any cause, the 10-year survival rate of the entire series was 92%±11%.

DISCUSSION

Despite the absence of wear and osteolysis, the long-term survival of these implants in young subjects should be improved. Although longer follow-up is necessary to formulate a definitive opinion, we tend to prefer cementless stem and cup fixation in ceramic-on-ceramic bearing systems.

LEVEL OF EVIDENCE

Level 4 retrospective study.

Prospective randomized trial comparing alumina ceramic-on-ceramic with ceramic-on-conventional polyethylene bearings in total hip arthroplasty

This prospective randomized study aims to compare the outcome between an alumina ceramic-on-ceramic (CC) articulation with a ceramic on ultra-high-molecular-weight polyethylene articulation (CP). Fifty-six hips in 55 patients with mean age 42.2 (range, 19-56) each received uncemented components, a 28-mm alumina head with randomization of acetabular liner. Mean St Michael's outcome score for each group with up to 10 years follow-up (median, 8 years; range, 1-10) was 22.8 and 22.9, respectively (P = .819). Wear was identified in all but 1 CP replacement, but only 12 of the 23 CC. Mean wear in the CP group was 0.11 mm/y and 0.02 mm/yr in the CC group (P < .001). Other than significantly greater wear in the polyethylene group, there was no significant difference in midterm outcome between the 2 groups.

Metal ions levels measurments for early total hip replacement malfunction diagnosis with "plasma-sprayed ceramic" bearings couple

Diagnosis of total hip arthroplasty malfunction is usually based on clinical and radiographic findings, while metal ion blood levels monitoring is generally recommended for metal-on-metal bearings hip replacements. However, these measurements may be very useful in detecting anomalies in other bearing surfaces such as plasma sprayed ceramic bearings. We report on the case of a patient with a painful cementless ceramic-on-ceramic total hip prosthesis (Plasmaceram) for which metal ions blood levels suggested revision surgery in the absence of any demonstrable radiographic anomaly. The high Cobalt and moderate Chromium ion levels in blood suggested a mechanical dysfunction of the bearing couple which revealed to be a severe cam effect requiring revision surgery of both components. Measurement of metal ion blood levels may play a substantial role in the assessment of a total hip prosthesis mechanism when using another bearing surface than metal-on-metal for which this measurement is usually recommended.

Delta ceramic-on-alumina ceramic articulation in primary THA: prospective, randomized FDA-IDE study and retrieval analysis

Wear and osteolysis continue to be major reasons for revision surgery in THA. Ceramic-on-ceramic bearings eliminate polyethylene wear debris. The newest generation of these bearings incorporate nanosized, yttria-stabilized tetragonal zirconia particles producing an alumina matrix composite. We asked whether this new material would perform as well as a conventional bearing in terms of functional hip scores, radiographic migration and osteolysis, complications and survival. As part of a US FDA investigational device exemption study (G000075), we conducted an initial prospective safety study of 21 alumina matrix composite femoral heads articulating on alumina liners followed by a prospective, randomized study with 44 more of these articulations and 45 zirconia femoral heads on polyethylene liners. The minimum followup for all patients was 26 months (mean, 73 months; range, 26-108 months). Harris hip scores and radiographic findings were similar in the two groups as was survivorship (trial 95% versus control 93%). There were three reoperations in the trial group and three in the control group. A fractured head retrieval showed a 33% monoclinic transformation with an increase in surface roughness from 3 to 5 nm at the main wear zone. While our numbers were insufficient to compare device-related complications, the trial device performed as well as the control device in terms of reoperation, and clinical and radiographic outcome. The alumina matrix composite femoral head on an alumina liner provided high survivorship.

LEVEL OF EVIDENCE

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

Alumina-on-alumina total hip arthroplasty in young patients: diagnosis is more important than age

Total hip arthroplasty (THA) in young patients has a high loosening rate, due in part to acetabular deformities that may compromise bone fixation and polyethylene wear. We therefore asked whether wear or osteolysis and loosening differ in patients under 40 years of age with alumina-on-alumina THA compared to those who are older. We prospectively followed 56 patients (63 hips) younger than 40 years (Group 1) and 247 patients (274 hips) older than 40 (Group 2) who had an alumina-on-alumina THA. The minimum followup was 4 years (mean, 5.6 years; range, 4-9 years). The two groups differed in various features: there were no patients with primary osteoarthritis in Group 1 and they had worse preoperative function and range of mobility, while weight, activity level, and implant size were greater in Group 2. The survival rate for cup loosening at 80 months postsurgery was 90.8% (95% confidence interval, 82.9-98.6%) for Group 1 and 96.5% (95% confidence interval, 94.2-98.7%) for Group 2. Cup loosening was less frequent with primary osteoarthritis than with severe developmental dysplasia of the hip. Although an alumina-on-alumina THA provided similar midterm survival and radiographic loosening in both age groups, the preoperative diagnosis seems more important than age for outcome. Continued followup will be required to determine if the alumina-on-alumina bearings in young patients result less risk of osteolysis and loosening.