Modular femoral stems for total hip arthroplasty (THA) were introduced to allow additional options for surgeons in controlling leg lengths, offset, and implant stability. This option is widely used in Region Emilia Romagna, Italy, where the study was conducted, having a modular neck stem nearly 35% of primary THA in 2013. Great majority of modular neck is made of Titanium alloy.

The study was designed as a retrospective descriptive case series of 67 hips in patients who underwent revision of a THA. All had a Titanium modular neck. In 44 cases revision was due to breakage of the neck, in the remaining 23 it was due to different reasons unrelated to modular neck such as bone fracture, breakage of a ceramic component, cup loosening.

Mean follow up was 3.5 yrs. For all patients excised capsule and surrounding tissue were graded for presence of necrosis, inflammatory exudate, lymphocytes, and wear particles using light microscopy of routine paraffin sections stained with hematoxylin and eosin. The retrieved modular neck-body and head-neck junctions were examined for evidence of fretting and corrosion. For some patient dosage of circulating Titanium was obtained. Approval was obtained from institutional review board.

It resulted that a variable amount of wear was observed in the first group of patients, with no evidence of lymphocytic reaction, but with variable notes of necrosis. Broken necks showed different patterns of damage, with different degree of corrosion, beside the fatigue fracture. In the second group wear was less evident or absent and negativity of lymphocyte reaction was substantially confirmed. Circulating Titanium ions were one order of magnitude higher in first group (mean 35 micrograms /litre).

It can be concluded that fracture of Titanium modular necks occurs progressively, wear does not induce lymphocytic reaction and circulating ions increase.

Ceramic-on-ceramic (CoC) total hip arthroplasty (THA) can produce articular noise during the normal activities, generating discomfort to the patient. THA noise has to be investigated also as a potential predictor and a clinical sign of prosthetic failure.

An observational study has been carried out to characterize the noise in CoC cementless THA, and to analyze the related factors. A total of 46 patients with noisy hip have been enrolled in 38 months, within the follow-up protocol normally applied for the early diagnosis of ceramic liner fracture [1]. Noise recording was based on a high-quality audible recorder (mod. LS 3, Olympus, Japan) and a portable ultrasonic transducer (mod USB AE 1ch, PAC, USA). The sensors for noise recording were applied to the hip of the patient during a sequence of repeatable motorial activities (forward and backward walking, squat, sit in a chair, flexion and extension of the leg). Sessions were also video-recorded to associate the noise emission to the specific movements.

Each noise event was initially identified by the operator and therefore classified by comparison to the spectral characteristics (duration, intensity and frequency) of the main noise types. Number and spectral characteristics of noise events were obtained and correlated to the factors describing the clinical status of the patient, the surgical approach, the prosthetic device implanted. The study investigated also the noise as a sign of implant failure, by comparison with the total number of implants failed in the cohort during the study.

We observed three types of noise with the main spectral characteristics in agreement to the literature: clicking, squeaking and popping. Among the identified types of noise, squeaking showed the longest duration and the highest amplitude. The 63% of hip presented the emission of just one type of noise, while the remaining a mix of types. The movement with the highest presence of noise was walking, followed by squat. Correlation was found between the noise type and the dimension of the ceramic head (p<0.001), with the sizes of 32 mm more affected by squeaking that the smaller one. Squeaking appeared before during the follow-up than the other types of noise. The 35% (16/46) of the noisy hips were revised during the study. Among the revised hips, the 81% (13/16) were affected by impingement and/or severe damage of the prosthetic components. The antiversion of the cup (p=0.008), the presence of debris in the synovial fluid (p=0.021) and the average frequency of squeaking (p=0.006) were significant predictors for the revision, but it has to be mentioned that the squeaking data was obtained on a small subset of revised patients. Ultrasonic analysis did not show significant correlations.

The study presented and validated an experimental procedure to analyze noisy hips in clinical trials. Noise is confirmed to be a significant parameter in the follow-up evaluation of ceramic THA.

The RIPO register collects data of all primary and revision hip replacement surgeries performed in Region Emilia-Romagna, Italy since 1stJanuary 2000.

The present study is aimed to analyze the survival rate of patients with Biolox®delta and Biolox®forte components, (CeramTec, Plochingen Germany) considering possible confounding factors. Only patients living in the region are considered in analysis, to avoid the bias resulting from the ‘loss’ of non-resident patients. The analysis has been conducted only on uncemented THA and monoblock, double mobility cups as well as such with pre-assembled inserts were excluded. Therefore, the finally analyzed database consists of 30’617 cases; 13’323 Biolox®forte and 17’294 Biolox®delta heads, articulating against ceramic or PE.

Unadjusted survival analysis was calculated according to Kaplan Meier method; with prosthesis failure as end point, defined as the revision of any prosthetic component for any cause.

To avoid a possible bias, revision of the prosthesis due to breakage of modular necks of the stem have not been considered. The results are summarized in Table 1.

*survival at 6 yrs follow-up

After adjusting for age and gender it resulted that Biolox®delta - XLpoly and Biolox®forte – poly increase the risk of revision (HR 1.4 and 1.2) compared to Biolox®delta - Biolox®delta;

When only ceramic fractures are considered, we observed 1 fracture of a 36 mm Delta head (1/8’917 = 0.01%) and 38 fractures of 28 mm Forte heads. The 38 fractures occurred mainly in cer-cer coupling (35/3’537 implants= 1%) and occasionally in cer-poly couplings (3/4’246 implants = 0.07%).

Fracture or damage of the Biolox®delta insert occurred in 10 implants out of 14’260(0.07%), while it had a higher incidence in Forte inserts (36 casesout of 6’932 implants = 0.52%).

It can be concluded that the presence of a poly liner decrease the survival of the implant. Beside this Biolox®delta significantly improved the resistance to fracture of both head and insert.

Modular femoral stems for total hip arthroplasty (THA) were introduced to allow additional options for surgeons in controlling leg lengths, offset and implant stability. This option is widely used in our Region, where the study was conducted, having a modular neck stem nearly 35% of primary THA in 2013. Great majority of modular neck is made of Titanium alloy.

The study was designed as a retrospective descriptive case series of 67 hips in patients who underwent revision of a THA. All had a Titanium modular neck. In 44 cases revision was due to breakage of the neck, in the remaining 23 it was due to different reasons unrelated to modular neck such as bone fracture, breakage of a ceramic component, cup loosening.

Mean follow up was 3.5 yrs. For all patients excised capsule and surrounding tissue were graded for presence of necrosis, inflammatory exudate, lymphocytes, and wear particles using light microscopy of routine paraffin sections stained with hematoxylin and eosin. The retrieved modular neck-body and head-neck junctions were examined for evidence of fretting and corrosion. For some patient dosage of circulating Titanium was obtained. Approval was obtained from institutional review board.

It resulted that a variable amount of wear was observed in the first group of patients, with no evidence of lymphocytic reaction, but with variable notes of necrosis. Broken necks showed different patterns of damage, with different degree of corrosion, beside the fatigue fracture. In the second group wear was less evident or absent and negativity of lymphocyte reaction was substantially confirmed. Circulating Titanium ions were one order of magnitude higher in first group (mean 35 micrograms /liter).

It can be concluded that fracture of Titanium modular necks occurs progressively, wear does not induce lymphocytic reaction and circulating ions increase.

After a few years from its introduction, the limits of the THA became evident, mainly due to high rates of mobilization for polyethylene wear and to the release of metal ions from MOM and MOP couplings.

Ceramic bearings were thus introduced in surgery to obtain lower levels of friction and wear.

These issues have now been well recognized by several studies, which show that ceramic-on-ceramic joint has the lowest wear rate among various articulations and that ceramic particles induce less macrophage reaction and decrease cytokine secretion, allowing to have little periprosthetic osteolysis.

After the first results in the late 70′s and early 80′s, the mechanical reliability was improved due to the manufacturers' efforts to reduce the ceramic fragility evolving average grain microstructure and lowering the degree of impurity.

Betterment and standardization of production have led to 3^rd generation alumina, Biolox Forte in 1994, that achieved a lower incidence of fracture.

The purpose of our study has been to assess long-term follow-up results of alumina-on-alumina 3^rd generation ceramic total hip cementless arthroplasty performed at our institution from January 1995 to December 2000.

We prospectively followed more than 200 patients operated of THA for primary or secondary hip osteoarthritis analyzing clinical and radiographs features.

In this period, the total hip replacement were performed by a single surgeon, who is the senior author (A.T.) in our Institution.

All patients were clinically examined to confirm the diagnosis and all of them were checked with a standard plain radiographs in two projections and, when necessary, the radiographic examination was completed by CT scans.

The same prosthesis was used in all patients, a 3^rd generation alumina COC articulation, composed of a hemispherical titanium alloy cup and a 28-mm alumina ceramic femoral head. The modular ceramic head was fixed to a 12/14 taper cone.

Proximally plasma-spray hydroxyapatite coated Ti alloy stems completes the implant features. Modular necks were used in retro or anteversion and varus or valgus offset, allowing changes in neck-shaft angle and giving a perfect intraoperative stability.

Clinical assessment was performed using the Merle-D'Aubigne and Postel hip score. Each patient was assessed before surgery, after 30 days, afterwards at 4 months and annually after surgery.

The mode of femoral component fixation was radiographically classified as bone ingrowth fixation, stable fibrous fixation or unstable fixation, according to the criteria Engh-Bobyn.

Osteolysis was evaluated on the femoral side at each Gruen zone. Osteolysis on the acetabular side was evaluated by DeLee and Chanley zone.

Our study has concluded that cementless modular hip arthroplasty with 3^rd generation ceramic-on-ceramic bearing, with a 13 to 18 years follow-up, shows an excellent survivorship, in particular for the very low volume release of microparticles during friction, which consequently reduction of cytokine release, thus diminishing the risk of periprosthetic osteolysis and loosening of implant components.

Summary Statement

A population based finite element study that accounts for subject-specific morphology, density and load variations, suggests that osteoporosis does not markedly lower the mechanical compliance of the proximal femur to routine loads.

Summary Statement

In a retrospective study, FE-based bone strength from CT data showed a greater ability than aBMD to discriminate proximal femur fractures versus controls.

Alumina–alumina bearings are among the most resistant to wear in total hip replacement. Examination of their surfaces is one way of comparing damage caused by wear of hip joints simulated in vitro to that seen in explanted bearings. The aim of this study was to determine whether second-generation ceramic bearings exhibited a better pattern of wear than those reported in the literature for first-generation bearings. We considered both macro- and microscopic findings.

We found that long-term alumina wear in association with a loose acetabular component could be categorised into three groups. Of 20 specimens, four had ‘low wear’, eight ‘crescent wear’ and eight ‘severe wear’, which was characterised by a change in the physical shape of the bearing and a loss of volume. This suggests that the wear in alumina–alumina bearings in association with a loose acetabular component may be variable in pattern, and may explain, in part, why the wear of a ceramic head in vivo may be greater than that seen after in vitro testing.

Alumina bearings are an available option in total hip replacements in the United States. Alumina has high strength and low friction and wear as an articulating surface. To determine the potential damage that can occur to alumina surfaces during implantation and dislocation of such bearings, we examined several explanted bearins at a microscopic and microchemical level.

Alumina femoral heads and acetabular liners that-were rejected during surgery because of metal staining, or removed from patients after known times of implantation were examined in the scanning electron microscope to observe the extent of surface degradation. 13 samples were examined. Four samples consisted of a femoral heads that had come in to contact with the metal acetabular shell during implantation, and therefore had metal staining on the surface. Nine femoral heads and a cetabular linerpairs were removed from patients with a history of recurrent dislocations of the prosthetic hip. Of these 5 pairs had grossly visible surface damage, and four did not. These latter four pairs, and the four femoral heads with surface staining were each coated with carbon and observed in a scanning electron microscope fitted with an energy dispersive X-ray analysis (EDAX) attachment for microchemical analysis.

Alumina heads that had inadvertently rubbed against the metalacetabular shell during surgery demonstrated dark metallic staining on the surface. EDAX analysis indicated that the stain had a composition very close to a Ti-6Al-4V alloy. Closer examination in the SEM revealed that the metal stain has a particulate structure, with the size of the particles ranging from sub-micron to several tens of microns. These titanium stains could be removed by a benign chemical etch, leaving no corrosion of the a lumina bearing surface. In contrast, alumina heads and liners removed after various times of implantation show significant surface deterioration. A wide range of features were observed, including uneven wear, cracks, embedded particles, deep groves and pits.

Considerable surface staining of aluminafemoral heads can occur during surgery if they come into contact with metal. This staining occurs due to surface deposition of metal particles which can be easily removed by wiping the surface with a benign etchant. If not removed, the presence of metal reduces the smoothness of the alumina, and may contribute to three-body wear. In contrast, alumina bearings removed from patients with multiple hip dislocations show significant, non-uniform-surface degradation. The observed features, such as embedded particles, cracks, and pits can contribute significantly to surface wear, which was grossly evident in 5 alumina head/liner pairs retrieved for this study. These data suggest that multiple dislocations in total hips with alumina bearings may need earlier surgical intervention because of the surface damage to the bearings, and potential for catastrophic wear.

Hydroxylapatite (HA) is widely employed as coating of cementless hip stems. Nevertheless there is a deficiency of long-term follow-up studies, and none, to our knowledge, with a ceramic on ceramic coupling, that it is important to avoid the effect of polyethylene wear on stem survival.

Between June 1990 and December 1991, 151 prostheses with an anatomic fully HA-coated cobalt-chrome stem, alumina bearing surfaces, and a threaded Ti-6Al-4V cup, were implanted in 147 consecutive patients (57 males, 90 females, average age 58 years). All were primary surgeries, there were no specific exclusions. Ten died for unrelated causes to the surgery, one died from postoperative complications; thirty nine of the surviving patients were lost to follow-up. The Merle D’Aubigné and Postel score was recorded before and after surgery at each review. An anteroposterior view and a frog-lateral view of the involved hip were taken at each follow-up review. The results were analysed by the Kaplan-Meier method to estimate the cumulative probability of revision.

In two cases, the prosthesis was completely removed with Gilderstone’s procedure because of septic loosening. Among the others, 10 cups required revision surgery for aseptic loosening, and 6 stems were revised for thigh pain. The mean Merle D’Aubigné rating improved from 10 before operation to 16.4. Bone stability was recorded in all cases but three in which there was a painfree fibrous stability. The Kaplan-Meier analysis at 12 years predicted asurvival rate for the prosthesis of 86% (95% CI 79 to 92), and for the stem of 93.8% (95% CI 89.7 to 98).

At 12 years the HA-coated stem has shown an overall good outcome while the threaded non HA-coated cup employed had a bad survival that had influenced the survival of the prosthesis. In conclusion we are confident to consider HA a viable and effective coating.

Aim: Polyethylene used for Total Hip Artrhroplasty components can be sterilized with different methods. Among them there is gamma rays. This method is currently used for conventional polyethylene and has been used also for Hylamer, a high cristallinity polyethylene manufactured by Depuy in early nineties. Recently Hylamer polyethylene components gamma sterilized in air were ‘recalled’ by Health Authorities, due to excessive wear. Aim of the present study was to evaluate radiographic and clinical performance of Hylamer acetabular liners gamma sterilized in air, and compare them to same devices gamma sterilized in nitrogen atmosphere.

Methods: Thirty-one patients “gamma in air” were matched to thirty controls with the same implanted socket but with the insert sterilized in a nitrogen atmosphere in a retrospective matched case-control. Moreover, a second control group was matched from twenty-three patients with a different prosthesis (ABG cup, Stryker-Howmedica) but with a similar insert made by conventional polyethylene gamma sterilized in absence of oxygen. Clinical evaluation was made according to the Harris Hip-scoring system. Radiographic wear measurements and osteolytic lesion was performed comparing the post-operative pelvic radiograph with the last follow-up study.

Results: Among 3 groups there was no significant difference in the clinical performance. At a mean of seven years, we found a significant difference between the mean rate of wear and osteolytic lesion of Hylamer sterilized in air and Hylamer sterilized in a nitrogen atmosphere.

Conclusion: We concluded that the manufacturing and sterilization processes influence the resistance to oxidation and wear of the various types of ultra-high molecular polyethylene that are currently available.

Total hip replacement procedures provide a very effective treatment modality for a wide range of diseases and injures to joints.

The annual number of primary and surgeries has been increasing. In Region Emilia Romagna, 4000000 inhabitants, 4587 total hip replacements (THA) were performed in 1997 and the number raised up to 5410 in 2002 ( + 18%). Emiarthoplasties were respectively 1914 and 2215 (+ 16%). Parallely number of revision raised from 550 to 938 (+71%).

In 2003 incidence of primary THAs in Emilia-Romagna is 107/100.000 inhabitants, higher than mean national value (76/100000).

Data of both primary and revision surgeries are collected by RIPO (Register for Orthopaedic Prosthetic Implantology) that started its activity in Rizzoli Institute on January 1990 and in Regione Emilia-Romagna on January 2000. The recording of data is done for each joint replacement operation and it consists on the identification of the patient, information about diagnosis or reason for re-operation, surgical approach, antibiotic and antithromboembolic prophylaxis, perioperative complications. Acetabular, femoral and head components are separately registered, on the basis of stickers with catalogue numbers provided by manufacturers with the implants. Fixation of the components is recorded as well.

Among the purposes of the Register there are the identification of early prosthesis failures, the information of surgeons on the outcome of their patients, the creation of a benchmarking tool for consultants and the speedy identification of relevant patients if a particular prosthesis or a particular batch gives cause for concern.

As for Scandinavian registers, revision is used as an end-point in the analyses. On this basis it is possible to calculate survival curves either aggregated or stratified.

By Cox multivariate analysis it has been ascertained that risk factors in total hip arthroplasties are represented by sex (females have lower risk than males), by age (younger than 40 are more at risk than 40–70s, and older than 70 are less at risk than 40–70s) and by pathology (fracture, coxites and Paget diseases have higher risk than coxarthrosis).

Basing on these data, survival analysis was normalized and the influence of articular coupling and fixation of the components on prosthesis outcome have been evaluated.

It resulted that failures are more likely to occur when metal on metal, or metal on polyethylene or ceramic on polyethylene devices rather than ceramic on ceramic implants are implanted.

Similarly cemented and hybrid THAs fail at higher rate than uncemented ones. All data are referred to a 11 years follow-up.

At present time Kaplan Meier analysis indicates a survival rate of total hip arthroplasties performed at Istituto Rizzoli of nearly 90% at ten years follow-up (9717 primary implants, 435 failures).

Main reasons for revisions are aseptic loosening of the cup (33%),aseptic loosening of both components (18%), aseptic loosening of the stem (17%), deep infection (7.9%),dislocation (7.6%),prosthesis fracture (3%) etc. Aseptic loosening represent, therefore, the most frequent cause for revision.

Results obtained at Istituto Rizzoli fit in the benchmarking set by the British NICE (National Institute for Clinical Excellence) that states that the revision rate should be of 10% or less at 10 years.

To improve these results attention should be pointed on new models: hip prosthesis technology is continually changing, with new designs and techniques being introduced. There is a need to strike a balance between using prostheses with published long-term performance data, and the need to develop and improve hip prosthesis. A solution to this problem could be to entrust reference clinical centers the evaluation of the effectiveness of any new prosthesis for at least three years, before opening free distribution in standard orthopaedic units,as suggested by NICE. Only models that reach the ‘entry benchmark’ in adequately sized, well conducted observational studies, can be implanted with a good safety. At present time it is unlikely that clinical evaluation data on long term effectiveness is required by Notified Body for ‘CE’ marking, unless new materials are involved in the manufacture. This happens despite the fact that even small changes to existing prostheses can have a significant impact on implant performance and revision rate.

Other factors than the already discussed can influence the surgery outcome, and among these the volume of operations performed in the hospital, the ability of the surgeon and its confidence with the technique, the compliance of the patient. Only an overall view of the situation will allow to reach the goal of reduction of need for revision of total hip arthroplasties.

Aims: The aim of this study is to report the pre-clinical validation and clinical experience with modular neck primary prosthesis.

Introduction: Modular acetabular designs are widespread used in primary THA for their versatility while little experience is reported with modular femoral designs. Stem modularity could be useful when the anatomy is overthrown and for mini-incision approaches, providing an increased adaptability without any need for a large inventory or expensive custom made prostheses.

Methods: The fretting-corrosion behavior of the neck-stem coupling and the amount of particulate released under simulated physiological activities were investigated. In vitro tests were performed in Ringer’s solution loading the stem up to 20 millions cycles (i.e. 20 yrs) according to ISO 7206. From January 1995 to December 2001, 864 primary surgeries were performed with a modular stem. There were 458 women and 406 men; the mean age was 55 years (16–81 years). The main pre-operative diagnosis was primary arthritis (58.1%), the second CHD (22.2%). The stem survival was estimated by the Kaplan-Meier method.

Results: Evidence of primary corrosion was not found, conversely areas showing fretting damage were seen. The amount of fretted material was estimated in less than 1mg/year. Clinically 3 stems were revised, 2 for recurrent dislocation, 1 for stem subsidence, none for mechanical failure. At 6 years the estimated stem survival is 99.4%.

Conclusions: Modular stems have shown excellent clinical and mechanical behavior. The amount of fretting debris product is negligible taking that a stable prosthesis is likely to produce more than 10mg/year of metal debris.

Aims: Aim of this study is to review the role of biomechanical modelling in computer aided orthopaedic surgery (CAOS), and to identify the issues that prevent a wider adoption of biomechanical modelling in the clinical practice.

Methods: we reviewed the experience we cumulated over the years in the use of biomechanical models to answer clinically relevant questions in the domains of joint prosthetics design and of skeletal strength under pathological conditions. also summarised the studies done in the past few years on the use of computer aided systems in the pre-operative planning, with particular reference to the Hip-OpA9 surgical planner for total hip replacement. Last, we analyse the improvements that the introduction of new technologies such as the Multimod Application Framework is likely to allow in a near future. All this information was combined in order to establish two possible scenarios for the next generation of computer aided orthopaedic surgery solutions: the use of biomechanics models as pre-operative and intra-operative decision-support instruments, and the role of multisensorial interfaces in CAOS applications.

Results: With this review we found that various technology limitation still limit a wider introduction of biomechanics modelling in CAOS. Specific research activities must be focused on the generation of patient-specific models of the musculo-skeletal apparatus that are not only anatomically but also functionally correct and accurate.

Conclusions: While multimodal imaging (CT+MRI+ SPECT) may provide the best results, solutions are being developed which are compatible with the logistics of the clinical practice.

Aims: To develop and test in the surgical theatre an intra-operative device, which could help the surgeon assessing the primary stability of cementless hip stem.

Methods: The device is basically a measurement instrument. It hosts two sterilization-proof sensors, giving separate signals of two magnitudes: a torque and an angle. The prototype has been designed to allow safe handling during surgical manoeuvres and easy insertion/ extraction in the stem under test. A series of leds gives the surgeon information concerning the load applied and the extent of implant stability achieved. A micro-motion threshold was set at 100 microns to discriminate between stable and unstable implants. The device was validated and calibrated in vitro on 5 cadaveric and 2 composite femurs (so as to cover a wide range of bone quality & size) hosting the same kind and size of stem, with increasing press-fit (Cristofolini, 2002). The prototype stability measurement was compared with that obtained with a previously validated in-vitro protocol (Monti et al.,1999), based on an additional high accuracy LVDT. A clinical trial is now in process.

Results: The validation yielded satisfactory results in terms of noise and drift (for both sensors < 0,05% of the range).The final prototype was then calibrated, comparing the device readout with the reference data from the additional LVDT. Good linear correlation was found (R2B30,98). The overall accuracy of the prototype was estimated analysing the data of all the femurs. The final prototype can predict implant stability with an error of 10% on the displacement limit (100 micron). After the first test in the operating room, the surgeons confirmed that the device was easy to handle and to use, and that the parameters extracted were clinically significant. Micromotions were recorded in implants considered sufficiently stable by the surgeons (confirming the stability threshold of 100 micron).

Conclusions: The prototype was successfully designed, validated and calibrated. The overall accuracy was deemed sufficient to discriminate between stable and unstable implants. The clinical trial highlighted the great advantage that this device can give to the surgeon in deciding if press-fit is sufficient.

Aims: The aim of this retrospective study is comparatively analysing cemented versus hydroxyapatite coated cementless þxation. A 10-year survival analysis of 2 patient cohorts operated by the same senior surgeons and with the same stem design was performed. Methods: Between 1990 and 2000, 1207 primary prostheses, 599 cemented and 608 cementless stems have been implanted. When mineral bone density and anatomic shape of the femur advised against inserting a cement-less stem a third generation cementing technique was chosen. In all cases an anatomic CoCr alloy stem and an alumina coupling were employed. Cementless stems were fully coated with hydroxyapatite. To provide homogeneity for preoperative diagnosis, only replacements for primary arthritis were considered. The remaining prostheses were 432 cemented and 366 cementless. The cumulative probability of revision for aseptic loosening of the stem was estimated by the Kaplan-Meier method. Results: 98.5% of the cemented stems and 96.7% of the cementless stems survived at 10 years, the difference between the 2 cohorts being statistically not signiþcant (p> 0.05). Conclusions: Using the same stem design and ceramic coupling, thus avoiding the confounding presence of polyethylene wears debris on study outcomes, allows for the reliable evaluation of stem þxation effectiveness. Noting that the evaluated survival rates are consistent with the literature, we are conþdent that at 10 years cementless stems performed as cemented.