Measurement of polyethylene wear in acetabular components inserted with and without cement. A randomized trial

Single-use versus reusable ancillaries for dual mobility cup in total hip replacement. A prospective randomized short-term safety and feasibility comparison

BACKGROUND

Single-use (SU) ancillaries for cup preparation in total hip arthroplasty (THR) aim to reduce the costs of hip replacement surgery. These devices have been recently introduced, but their safety and feasibility have not been studied. Therefore, we performed a prospective randomized study aiming to assess the impact in our department of using these SU ancillaries versus standard reusable ancillaries for dual mobility THR regarding 1) the cost, 2) operative time, 3) quality of primary fixation.

HYPOTHESIS

We hypothesized that the use of SU ancillaries for acetabular preparation would reduce maintenance costs, and so optimise the operating procedure, reduce the overall cost of surgery, save time, while maintaining the same quality of prosthesis fitting.

METHOD

We conducted a randomised, controlled, open-label, two-arm, single-centre, prospective therapeutic trial with a medico-economic objective. Inclusions were made prospectively from patients hospitalised and surgically managed in our department for arthrosis over 18 years old treated with dual mobility THR.

RESULTS

In the current study, 18/20 (90%) of the cases required the use of one SU reamer when using SU ancillaries. Only two cases (10%) required a second SU reamer (without SU failure regarding the acetabular implant) because there was too much subchondral bone left and not enough cancellous bone allowing correct cup fitting. We also found that the test implant supplied in the SU kit had a less secure press-fit than the reusable metal test implants. There was one of primary press-fit failure in the SU group requiring a different cup with additional screws. The estimated cost to the supplier per procedure was 20,105 euros using single-use reamers versus 26,666 euros using conventional ancillary kits, a saving of 6561 euros (p<0.001). For the healthcare institution, the median price per intervention on the differentiating points was 2648 euros versus 2580 euros, with no significant difference (p=0.297). The results show an average societal cost of 52,199 euros using single-use and 53,572 euros using reusable ancillary equipment, with a significant difference between the two groups (p<0.003). The average cost of Healthcare Risk Waste (HCRW) disposal in the SU group was 5.2 euros per intervention against 5.1 euros in the RU group, without significant difference (p=0.910). We found a similar result for the cost of disposal of non-HCRW waste per procedure: 0.37 euros in the SU group versus 0.34 in the RU group, without significant difference (p=0.345).

CONCLUSION

SU ancillaries significantly reduce the table set up time and have the potential to facilitate time and cost savings but further research is needed in this direction. Our study shows that the daily workload, operating times, and the number of boxes of instruments to be sterilised are decreased. The associated environmental gain is significant. Nevertheless, the economic promise of these SU ancillaries is only partially supported in this trial owing to the small number of patients. Further work will be needed to obtain a more powerful medico-economic assessment of this promising ancillary product.

LEVEL OF EVIDENCE

II; prospective randomized study.

Survival and complications of total hip arthroplasty using third-generation dual-mobility cups with non-cross-linked polyethylene liners in patients younger than 55years

BACKGROUND

In younger patients, total hip prostheses are subjected to wide motion ranges and wear-inducing forces. Dual-mobility cups (DMCs) are effective in decreasing the risk of dislocation. However, wear and osteolysis have been reported with first-generation DMCs. These complications have not been assessed in younger patients managed with third-generation DMCs associated with a lower risk of intra-prosthetic dislocation (IPD). We therefore designed a retrospective study of patients younger than 55years at THA with third-generation DMCs. Our objectives were to evaluate (1) the complication rate, and (2) the survival rate.

HYPOTHESIS

The rate of complications of THA with third-generation DMCs in patients younger than 55years of age is comparable to that in the general population of THA patients.

MATERIAL AND METHODS

This retrospective study included 79 consecutive patients (91 hips) who had total hip arthroplasty (THA) between 2007 and 2012. We included all patients younger than 55years who underwent primary THA with a third-generation DMC and a liner made of non-cross-linked polyethylene. The patients were evaluated clinically and radiologically.

RESULTS

Mean follow-up was 9.8years (range: 2-13years). At last follow-up, no patient had experienced prosthetic dislocation or IPD. Aseptic and septic cup loosening each occurred in 1 patient. In all, 7 (7.7%) patients required revision surgery with exchange of at least one component (cup loosening, n=2; neck fracture with a short stem fixed to the neck, n=1; peri-prosthetic femoral fracture, n=1; infection, n=1; and femoral-stem loosening, n=2). Peri-acetabular osteolysis developed in 2 (2.2%) hips. Cup survival to aseptic loosening was 98.9% (95% confidence interval, 97%-100%) and survival to revision for any reason except infection was 95.6% (95% confidence interval, 82%-100%).

DISCUSSION

In patients younger than 55years, third-generation DMCs were associated with absence of prosthetic dislocation, absence of IPD, and a low revision rate for cup loosening, in the medium term. These implants therefore constitute a viable treatment option in younger patients requiring THA.

LEVEL OF EVIDENCE

IV, retrospective study.

Cementless hydroxyapatite-coated stem with dual mobility and posterior approach in over-80 year-old patients with osteoarthritis: Rates of dislocation and periprosthetic fracture at a mean 8 years' follow-up

BACKGROUND

Straight cementless stems are common in primary total hip arthroplasty (THA) in the elderly, but controversial due to higher risk of loosening and periprosthetic fracture (PPF). Apart from registries, results for the Corail implant and dual mobility (DM) in over-80 years-old are not known, notably in case of systematic association to a DM cup. We therefore performed a retrospective analysis of Corail implants in patients aged≥80years at implantation for osteoarthritis of the hip, assessing 1) PPF rate and survival for cementless straight stems associated to DM cups, 2) complications, and dislocation in particular, and 3) clinical scores.

HYPOTHESIS

PPF and dislocation rates are low in THA with cementless straight stem associated to DM cup in patients aged≥80years.

PATIENTS METHODS

A retrospective study was conducted in our department for the period July 2007 to December 2012. Inclusion criteria were age≥80years, with primary THA for osteoarthritis. Exclusion criteria were revision procedure and femoral neck fracture. One hundred and twenty-eight consecutive THAs were included, in 120 patients, with a minimum 5years' follow-up. Clinical results were assessed on Harris Hip Score (HHS) and Oxford Hip Score (OHS). Data were collected for PPF or dislocation and other complications.

RESULTS

At a mean 8±1 years' follow-up (range, 5-10 years), 66 patients (55%, for 68 hips) were alive, 48 (40%, for 54 hips) had died, and 6 (5%, for 6 hips) were lost to follow-up. Median age at surgery was 83years (range, 80-93years). Mean OHS at last follow-up was 41±6 (range, 21-48) and HHS 83±14 (range, 23-100) with mean gain of 32 points (95% CI, [28-36]; p<0.001)). There were 2 cases (1.6%) of PPF, at 2 and 65months, and no dislocations or cases of aseptic loosening. There were 2 cases (1.6%) of intraoperative calcar fracture, treated by wire cerclage with immediate complete weight-bearing, without further complications. With death as a competing risk, cumulative 10-year incidence of femoral stem revision was 1.6% [95% CI: 0.4-6.5], and cumulative incidence of all-cause revision was 4.1% [95% CI: 1.7-9.7].

DISCUSSION

In an over-80 year-old population, primary THA with straight cementless stem and 2nd generation dual mobility cup was an effective option with low risk of PPF or dislocation after a minimum 5-year of follow-up.

LEVEL OF EVIDENCE

IV; retrospective study.

Wear and damage in retrieved humeral inlays of reverse total shoulder arthroplasty-where, how much, and why?

BACKGROUND

Polyethylene (PE) wear and material degradation have been reported as complications in reverse total shoulder replacements (rTSAs). In this regard, scapular notching is associated with more clinical complications. Therefore, the purposes of the study were to quantify the linear and volumetric wear, as a measure for the amount of removed material, and to qualitatively assess the PE damage modes to describe the material degradation in retrieved rTSA humeral PE inlays that contribute to failure of shoulder replacements. Furthermore, this study aimed to evaluate the effect of scapular notching on PE wear and rim damage of the humeral components.

METHODS

The total study population of 39 humeral inlays contains 2 cohorts that were used for the damage mode analysis and for the wear analysis, respectively. The extent and presence of wear damage modes in 5 defined zones were assessed by a grading system for all PE joint replacements. For quantitative wear analysis the most frequent design (n = 17) was chosen. Using a coordinate-measuring machine and postprocessing software, volumetric wear measurements for the retrieved humeral PE inlays were undertaken. Furthermore, prerevision radiographs were analyzed for scapular notching. Finally, retrieval findings were correlated with clinical and radiographic data to consider the effect of notching and to identify risk of failures for these prostheses.

RESULTS

Damage on the rim of the humeral PE inlays was more frequent and severe than on the intended articulation surface. Irrespective of the damage mode, the inferior rim zone sustained the greatest amount of wear damage followed by the posterior zone. Burnishing, scratching, pitting, and embedded particles are most likely to occur in the articular surface area, whereas surface deformation, abrasion, delamination and gross material degradation are predominantly present in the inferior and posterior rim zones. The retrieved inlays exhibited a mean volumetric wear rate of 296.9 mm³/yr ± 87.0 mm³/yr. However, if the notched and non-notched components were compared, a significant higher volumetric wear rate (296.5 ± 106.1 mm³/yr) was found for the notched components compared to the non-notched group (65.7 ± 7.4 mm³/yr). Generally, there was a significantly greater incidence of damage and greater amount of wear if scapular notching occurred.

CONCLUSION

The notched components showed a 5-fold increase in PE wear rate. Therefore, scapular notching has a strong effect on PE damage and wear. If scapular notching can be clinically avoided, the PE wear performance is in a similar magnitude as found for hip and knee replacements.

Use of morselized allografts for acetabular reconstruction during THA revision: French multicenter study of 508 cases with 8 years' average follow-up

BACKGROUND

In the context of acetabular reconstruction, bone defects can be filled with processed or unprocessed bone allografts. Published data are often contradictory on this topic and few studies have been done comparing processed allografts to fresh-frozen ones. This led us to conduct a large study to measure the factors impacting the survival of THA revision: (1) type of allograft and cup, (2) technical factors or patient-related factors.

HYPOTHESIS

Acetabular reconstruction can be performed equally well with frozen or processed morselized allografts.

MATERIALS AND METHODS

This retrospective, multicenter study of acetabular reconstruction included 508 cases with a minimum follow-up of 5 years. The follow-up for the frozen grafts was shorter (7.86 years±1.89 [5-12.32]) than that of the processed grafts (8.22 years±1.77 [5.05-15.48]) (p=0.029). However, the patients were younger at the time of the primary THA procedure in the frozen allograft group (51.5 years±14.2 [17-80]) than in the processed group (57.5 years±13.0 [12-94]) (p<0.001) and were also younger at the time of THA revision (67.8 years±12.2 [36.9-89.3] versus 70 years±11.7 [25-94.5]) (p=0.041).

RESULTS

There were more complications overall in the frozen allograft group (46/242=19.0%) than the processed allograft group (35/256=13.2%) (p=0.044) with more instances of loosening in the frozen group (20/242 [8.2%]) than in the processed group (6/266 [3.3%])(p=0.001). Conversely, the dislocation rate (16/242=6.6% vs. 17/266=6.4%) (p=0.844) and infection rate (18/242=7.4% vs. 15/266=5.7%) (p=0.264) did not differ between groups. The subgroup analysis reveal a correlation between the occurrence of a complication and higher body mass index (BMI) (p=0.037) with a higher overall risk of complications in patients with a BMI above 30 or under 20 (p=0.006) and a relative risk of 1.95 (95% CI: 1.26-2.93). Being overweight was associated with a higher risk of dislocation (relative risk of 2.46; 95% CI: 1.23-4.70) (p=0.007). Loosening was more likely to occur in younger patients at the time of the procedure (relative risk of 2.77; 95% CI: 1.52-6.51) (p=0.040) before 60 years during the revision. Lastly, patients who were less active preoperatively based on the Devane scale had an increased risk of dislocation (relative risk of 2.51; 95% CI: 1.26-8.26) (p=0.022).

DISCUSSION

Our hypothesis was not confirmed. The groups were not comparable initially, which may explain the differences found since the larger number of loosening cases in the frozen allograft group can be attributed to group heterogeneity. Nevertheless, morselized allografts appear to be suitable for acetabular bone defect reconstruction. A randomized study would be needed to determine whether frozen or processed allografts are superior.

LEVEL OF EVIDENCE

III, comparative retrospective study.

Total knee replacement on more than 20° valgus: A case control study

INTRODUCTION

Lower-limb valgus deformity exceeding 20° is a particular case, with few publications assessing the impact of the severity of the valgus. The present retrospective case control study compared a series of>20° valgus versus a series of 10-20° valgus, assessing (1) operative data [approach, type of total knee replacement (TKR)], (2) complications and implant survival, and (3) clinical and radiological results.

HYPOTHESIS

Severe valgus deformity requires TKR with greater constraint, incurring a higher rate of complications and poorer implant survival.

MATERIAL AND METHOD

A multicenter retrospective study for the period January 2006 to December 2010 included 53 patients, with a mean age of 72±10 years, presenting>20° valgus. The study series was matched for age and gender with a series of 53 cases of 10-20° valgus. Convexity laxity was greater in the>20° group (p=0.004).

RESULTS

There was no significant inter-group difference in approach (p=0.13). Greater constraint was more frequent in the>20° group (7/53 versus 1/53; p=0.03), independently of convexity laxity or Krackow grade (p=0.14). There were 7 complications (13.2%) in the>20° group and 7 in the 10-20° group (NS). Eight-year survivorship was 95.12% in the>20° group and 94.9% in the 10-20° group (p=0.63). There were no significant differences in Oxford score (p=0.30) or HKA angle (p=0.78) at last follow-up.

CONCLUSION

The study hypothesis was partially confirmed: greater constraint was more frequent in>20° valgus. The number of complications was low, and survival was identical to that of a control group with less severe deformity.

LEVEL OF EVIDENCE

III, retrospectivecase controlstudy.

Total knee arthroplasty in patients with varus deformities greater than ten degrees: survival analysis at a mean ten year follow-up

INTRODUCTION

Total knee arthoplasty (TKA) is a secure procedure with more than 90% survival at ten years. The purpose of this study was to report both clinical and radiological outcomes of TKA with a varus > 10°. The second objective was to identify risk factors for failure or bad clinical results. Our hypothesis was that results and survey are comparable to TKA with lesser deformities.

METHODS

Eighty-two TKA (69 patients) between January 2004 and December 2008 with a varus > 10° were reviewed retrospectively. The endpoints were clinical (range of motion, IKS knee score, Oxford, and SF-12) and radiological (HKA post-operative and the existence of radiolucent lines or loosening at last follow-up).

RESULTS

Sixty-three TKA (55 patients) were assessed with a mean follow-up of 10.9 years. The global IKS score significantly increased (p = 0.04). Seven TKA needed a revision: two for sepsis, four for aseptic loosening, and one for polyethylene wear, with an overall survival of 91.6% at ten years. For aseptic loosening, the survival rate was 94.7% at ten years. Risk factors for failure were age (p = 0.001), weight (p = 0.04), and a post-operative HKA lesser than 175° (p = 0.05) for aseptic loosening.

DISCUSSION

The hypothesis was confirmed: the results showed a significant improvement of function and quality of life with a survival rate comparable to those found in the literature for greater varus but also inferior to 10°. Three risk factors have been identified suggesting increased surveillance in these cases.

CONCLUSION

The results of this survey confirm the work hypothesis. Total knee arthroplasty in patients with important axial deformities is a confirmed, reliable, patient-friendly and predictable good outcome procedure.

Femoral offset found not to affect metal ion levels in metal-on-metal total hip arthroplasty

BACKGROUND

Failure to restore femoral offset in metal on polyethylene total hip arthroplasty (THA) causes polyethylene wear and aseptic loosening. To our knowledge, no study to date has investigated the relationship between femoral offset and wear in metal-on-metal (MOM) THA.

AIMS

In this study, we investigated the relationship between femoral offset and wear by measuring circulating metal ion levels in MOM THA.

METHODS

In this retrospective study, we identified patients who had undergone MOM THA with the ASR XL system (DePuy International Ltd., Leeds, UK). Femoral offset was measured using anteroposterior radiographs, and circulating metal ion levels (cobalt and chromium) were recorded.

RESULTS

In total, 95 patients were included (68 males and 27 females). The mean age at the time of surgery was 64.9. Mean time from surgery to blood sampling was 15.4 months. No statistically significant relationship was found between femoral offset and cobalt (p = 0.313) or chromium (p = 0.401) ions.

CONCLUSION

It is known that failure to restore femoral offset during THA can lead to high rates of wear in metal-on-polyethylene articulations. In our study, no statistically significant relationship was found between femoral offset and serum cobalt or chromium ions. This study adds to the information available to surgeons regarding factors that increase wear in metal-on-metal total hip arthroplasty.

Comparative Analysis of the Reconstruction of Individual Hip Anatomy Using 3 Different Cementless Stem Designs in Patients With Primary Hip Osteoarthritis

BACKGROUND

We questioned whether there was a radiographic difference in hip geometry reconstruction and implant fixation between 3 different cementless stem design concepts in patients with primary end-stage hip osteoarthritis.

METHODS

We retrospectively evaluated the preoperative and postoperative radiographs by 2 independent and blinded reviewers in a series of 264 consecutive patients who had received either a straight double-tapered stem with 3 offset options (group A), a straight double-tapered stem with 2 shape options and modular necks (group B), and a bone-preserving curved tapered stem with 4 offset options (group C). The following parameters were assessed: acetabular, femoral and hip offset (HO), center of rotation height, leg length difference (LLD), and the endosteal fit of stem in the proximal femur (canal fill index). Group comparisons were performed using a one-way analysis of variance and subsequent pairwise comparisons (t-test).

RESULTS

Postoperatively, HO could be equally restored with all 3 stem designs (P = .079). The postoperative LLD was smaller in group C compared to group A (0.8 mm [standard deviation, 3.2] vs 2.6 mm [standard deviation, 4.5], P = .002). Best combined reconstruction of HO and LLD could be achieved with the short curved stem by junior and senior surgeons (HO: -2.0 and -2.1 mm; LLD: 1.9 and 0.7 mm, respectively). The proximal and mid-height canal fill indexes were higher in groups B and C compared to group A, indicating a better metaphyseal and diaphyseal fit in the proximal femur (both P < .001).

CONCLUSION

All 3 cementless stem designs allowed for good hip geometry reconstruction. Multiple shape and offset options allowed for a better metaphyseal stem fit and offered minor clinical advantages for leg length reconstruction. Modular necks did not provide reconstructive advantages in patients with primary hip osteoarthritis.

Analysis of polyethylene wear of reverse shoulder components: A validated technique and initial clinical results

One of the most prevalent phenomena associated with reverse total shoulder arthroplasty (rTSA) is scapular notching. Current methods examine only the damage to the scapula and no methods are available for quantifying the total wear volume of the polyethylene humeral bearing. Quantifying the polyethylene material loss may provide insight into the mechanism for scapular notching and into the particle dose delivered to the patient. A coordinate measurement machine (CMM) and custom computer algorithms were employed to quantify the volumetric wear of polyethylene humeral bearings. This technique was validated using two never-implanted polyethylene humeral liners with a controlled amount of wear in clinically relevant locations. The technique was determined to be accurate to within 10% of the known value and within 5 mm³ of the gravimetrically determined values. Following validation, ten retrieved polyethylene humeral liners were analyzed to determine a baseline for future clinical tests. Four of the ten polyethylene humeral liners showed visible and measureable wear volumes ranging from 40 to 90 mm³ total with a maximum wear rate as high as 470 mm³ /year in one short duration and significantly damaged humeral liner. This validated technique has the potential to relate patient outcomes such as scapular notching grades to polyethylene release into the body. While the total wear volumes are less than reported in literature for cases of osteolysis in knee and hip patients, dosages are well within the osteolytic thresholds that have been suggested, indicating that osteolysis may be a clinical concern in the shoulder. This work provides the basis for future studies that relate volumetric wear to patient outcomes. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:980-987, 2017.

Cementless lateralized stems in primary THA: Mid-term survival and risk factors for failure in 172 stems

INTRODUCTION

Increasing the femoral offset when performing total hip arthroplasty (THA) theoretically increases the stresses and risks of the stem not integrating itself into bone. But this concept has not been validated for cementless stems; this led us to conduct a retrospective study to determine: (1) the risk factors for the occurrence of symptomatic femoral radiological abnormalities, (2) the incidence of these abnormal radiological findings, (3) the revision rate for aseptic non-integration of a cementless lateralized stem.

HYPOTHESIS

Young patients with significant femoral canal flare and a small cementless lateralized stem have a higher risk of abnormal osseointegration.

MATERIAL AND METHODS

We analyzed retrospectively 172 consecutive lateralized stems (KHO, Corail™ product line) implanted during primary THA between 2006 and 2012 in 157 patients (mean age 68years±12.6 (20-95), 89% men). Radiographs were used to evaluate osseointegration scores, offset restoration and the Noble index. Kaplan-Meier survival analysis was performed using "symptomatic femoral radiological abnormalities" and "revision for aseptic stem non-integration" as endpoints.

RESULTS

The mean follow-up was 5.9years±2.7 (range, 2-12.4years). Being more than 70years of age (HR=0.7, 95% CI: [0.3-0.9], P=0.004) and having a larger stem (HR=0.6, 95% CI: [0.4-0.9], P=0.03) were protective against symptomatic femoral radiological abnormalities, while increasing the postoperative femoral offset (HR=1.1, 95% CI: [1.01-1.2], P=0.02) was deleterious. The survival free of "symptomatic femoral radiological abnormalities" was 93% (95% CI: 89-97) at 5years and 84% (95% CI: 75-95) at 8years. The survival free of "revision for aseptic stem non-integration" was 98% (95% CI: 96.8-100) at 5years and 97% (95% CI: 95.2-100) at 8years.

DISCUSSION

In this study, the risk factors for symptomatic radiological abnormalities were being less than 70years of age, having a small lateralized stem and restoring a large femoral offset. Lateralized stems used in this study had a 10% rate of symptomatic radiological abnormalities and a 4% rate of revision for aseptic non-integration.

LEVEL OF EVIDENCE

IV, retrospective study.

Compared fixation and survival of 280 lateralised vs 527 standard cementless stems after two years (1-7)

BACKGROUND

Restoring the native hip anatomy increases hip prosthesis survival, whereas increased femoral lateralisation creates high torque stresses that may alter prosthesis fixation. After finding lucent lines around cementless lateralised stems (Corail™, DePuy Synthes, St Priest, France) in several patients, we evaluated the effects of lateralisation in a large case-series. The objective of our study was to compare lateralised vs standard stems of identical design in terms of radiological osteo-integration and survival.

HYPOTHESIS

Lateralised stems, despite being used only when indicated by the anatomical parameters, carry a higher risk of impaired osteo-integration.

MATERIALS AND METHODS

A retrospective study was conducted in 807 primary total hip arthroplasties (THAs) performed between 2006 and 2010 in 798 patients with a mean age of 65 ± 14.2 years. Lateralised stems were used in 280 cases (Corail High Offset KHO, n = 169; and Corail coxa vara KLA, n = 111 cases) and standard stems in 527 cases (Corail KA). Mean follow-up was 2.3 years (range, 1-7 years). The clinical evaluation included determination of the Postel-Merle d'Aubigné (PMA) score. Bone fixation and stability of the implants were assessed by determining the Engh and Massin score and the ARA score on the radiographs at last follow-up. Femoral, acetabular and global offset values were determined before and after THA. Nobles's Canal Flare Index was computed. Survival was estimated using the Kaplan-Meier method with surgical revision for aseptic loosening as the end-point.

RESULTS

The PMA score improved from 12 (10-15) pre-operatively to 17.7 (14-18) (P < 0.05). After THA, in the lateralised stem group, femoral offset was restored in 217 (77%) hips and the mean change vs the pre-operative offset value was -2 mm; in the standard stem group, femoral offset was restored in 440 (83.5%) hips and the mean change was +1 mm. The Engh and Massin score values were similar in the standard stem and lateralised stem groups (24.4 ± 2.2 and 22.6 ± 2.4, respectively, NS). Revision for aseptic loosening was required in 5 patients with lateralised stems (3 KHO and 2 KLA) versus none of the patients with standard stems. There were no cases of excessive femoral offset and the mean change in offset was -2.3mm (-5.3 to -1.1). Noble's index was increased (4.27 ± 0.5 for the loosened lateralised stems, 3.65 ± 0.8 for the well-fixed lateralised stems and 3.82 ± 0.6 for the standard stems), with no significant difference across groups. Overall survival after 3.5 years of follow-up was 94.6% (95% confidence interval, 88.4-100%) with lateralised stems and 100% with standard stems (P < 0.05).

DISCUSSION

The risk of aseptic loosening was significantly higher with the lateralised stem (5/280, 1.8%) than with the standard stem (n = 0). Our findings indicate a need for careful preparation to obtain primary fixation of lateralised stems.

LEVEL OF EVIDENCE

III, retrospective case-control study.

Excellent short-term results of hip resurfacing in a selected population of young patients

BACKGROUND

Hip resurfacing (HR) is an alternative option to total hip arthroplasty (THA) in a population of selected patients (young and/or active).

HYPOTHESIS

The short-term survivorship rate is as least as good as that for THA with no abnormal increase in serum metal ion levels.

MATERIALS AND METHODS

A continuous prospective series of 502 hip resurfacings in 481 patients mean age 48.7 years old (±10.3; 18-68) (Conserve Plus, Wright Medical Technology) was analyzed clinically, radiologically and biologically (total blood chrome, cobalt and titanium metal ion levels). Mean follow up was 4.1 years (1.9-4.9).

RESULTS

There were no dislocations. There were 5 cases of revision surgery with component replacement (including 2 infections). Implant survivorship using implant removal as the criteria (excluding infection) was 99.4% at 4 years (CI 95%: 98.1-99.8). The evaluation of metal ion levels showed a significant increase in cobalt from a preoperative level of 0.24 μg/L (0.01-3.6) to 0.86 μg/L (0.01-5.7) at the final follow-up (P<0.001). Chrome and titanium levels went from 0.68 μg/L (0.01-4.4) and 2.36 μg/L (0.39-7) to 1.28 μg/L (0.1-5.5) and 4.49 μg/L (1.29-8.21) respectively (P<0.001). All clinical scores had significantly improved at the final follow-up. Mean frontal plane cup inclination was 42.7° (35-62).

DISCUSSION

In a selected population of young and/or active patients, the short-term results of hip resurfacing are excellent. At the postoperative 4-year follow-up the rate of complications (in particular the absence of dislocations) was less than that for THA in young and/or active patients. Certain conditions must be respected to obtain these results; frontal plane cup inclination of between 40 and 45°, a femoral head diameter of at least 48 mm and good quality femoral bone.

LEVEL OF EVIDENCE

IV.

Influence of surgical approach on component positioning in primary total hip arthroplasty

Background

Minimal invasive surgery (MIS) has gained growing popularity in total hip arthroplasty (THA) but concerns exist regarding component malpositioning. The aim of the present study was to evaluate femoral and acetabular component positioning in primary cementless THA comparing a lateral to a MIS anterolateral approach.

Methods

We evaluated 6 week postoperative radiographs of 52 hips with a minimal invasive anterolateral approach compared to 54 hips with a standard lateral approach. All hips had received the same type of implant for primary cementless unilateral THA and had a healthy hip contralaterally.

Results

Hip offset was equally restored comparing both approaches. No influence of the approach was observed with regard to reconstruction of acetabular offset, femoral offset, vertical placement of the center of rotation, stem alignment and leg length discrepancy. However, with the MIS approach, a significantly higher percentage of cups (38.5 %) was malpositioned compared to the standard approach (16.7 %) (p = 0.022).

Conclusions

The MIS anterolateral approach allows for comparable reconstruction of stem position, offset and center of rotation compared to the lateral approach. However, surgeons must be aware of a higher risk of cup malpositioning for inclination and anteversion using the MIS anterolateral approach.

The Usefulness of Three-dimensional Computed Tomography as an Assessment of Periacetabular Osteolysis in Revision Total Hip Arthroplasty

Purpose

This study was performed to determine the usefulness of three-dimensional computed tomography (3D-CT) in measuring periacetabular osteolysis by comparing the real volume of osteolysis in revision surgery.

Materials and Methods

Twnety-three patients who had undergone revision surgery due to periacetabular osteolysis but not included septic osteolysis and implant loosening. The mean age of patients at the time of surgery was 55.2 years. And the mean time interval between the primary total hip arthroplasty and revision surgery was 13.3 years. We measured the polyethylene wear in plain radiographs using computer assisted vector wear analysis program, the volume of acetabular osteolytic lesions in high-resolution spiral CT scans using Rapidia 3D software version 2.8 algorithms before the revision surgery were performed. Intraoperative real osteolytic volume was calculated as the sum of the volumetric increments of the acetabular cup and impacted allo-cancellous bone volume.

Results

Strong correlation was found between the volume of acetabular osteolytic lesions measured on 3D-CT and intraoperative real osteolytic volume which was calculated as the sum of the volumetric increments of the acetabular cup and impacted allo-cancellous bone volume.

Conclusion

3D-CT is considered a useful method for assessing and measuring the volume of periacetabular osteolysis before revision surgery.

Risk factors for periacetabular osteolysis and wear in asymptomatic patients with uncemented total hip arthroplasties

Osteolysis is a silent disease leading to aseptic loosening. This has not been studied in a cohort of asymptomatic patients. The aim of this study was to detect factors that might be associated with the development of periacetabular osteolysis and wear around an uncemented cup. We assessed 206 patients with an uncemented cup, measuring wear and periacetabular osteolysis using computed tomography with a median follow-up of 10 years after surgery (range 7–14 years). EQ5D, pain from the hip, and satisfaction were assessed. The association between periacetabular osteolysis and wear, age, gender, activity, BMI, cup type, cup age, positioning of the cup, and surface coating was investigated with a proportional odds model. Wear and male gender were associated with an increased risk for periacetabular osteolysis. There was no association with periacetabular osteolysis for time from operation, patient age, UCLA Activity Score, liner thickness at time of operation, BMI, cup positioning, and type of implant. A thin liner at time of operation is correlated to increased wear. Linear wear rate was 0.18 mm/year and 46 of 206 patients had large periacetabular osteolysis. Asymptomatic patients with these implants should be followed up on a regular basis with a sensitive method such as CT in order to detect complications early.

Does prior conservative surgery affect survivorship and functional outcome in total hip arthroplasty for congenital dislocation of the hip? A case-control study in 159 hips

INTRODUCTION

The results of total hip arthroplasty (THA) in congenital dislocation of the hip (CDH) are well known, but such is not the case for the impact of prior conservative surgery on THA function and survivorship. The present study compared THA in CDH with prior conservative bone surgery (BS group) versus no prior bone surgery (NBS group), to (1) assess the impact of prior conservative surgery on function and survivorship after THA, and (2) determine whether a particular type of conservative surgery affected function or survivorship.

HYPOTHESIS

Prior conservative surgery for CDH does not affect function or survivorship of subsequent THA.

PATIENTS AND METHODS

A multicenter retrospective case-control study analyzed 430 THAs in CDH patients (332 patients: 269 female, 63 male; mean age, 56 years [range, 17-80 years]) at a mean 13.2±5.4 years' follow-up (range, 1-29 years). The BS group included 159 hips (37%) (64 pelvic, 81 femoral and 14 combined pelvic and femoral osteotomies), and the NBS group 271 (63%). Groups were comparable for gender, age at surgery, Devane activity score, preoperative Postel Merle d'Aubigné (PMA) functional score and CDH radiographic type following Crowe.

RESULTS

At follow-up, PMA scores were comparable: BS, 16.8±1.4 (11-18); NBS, 16.9±1.5 (7-18). Fifteen-year survivorship censored for implant revision for whatever reason did not significantly differ: BS, 87% (95% CI: 83-91%); NBS, 89% (95% CI: 86-92%). Ten-year survivorship on the same criterion did not significantly differ according to type of prior surgery: hip shelf arthroplasty, 97% (95% CI: 95-99%); Chiari osteotomy, 100%; femoral osteotomy, 95% (95% CI: 92-98%); and Milch osteotomy 96% (95% CI: 93-99%).

DISCUSSION/CONCLUSION

Conservative surgery for CDH does not impair the functional results or survivorship of subsequent THA.

LEVEL OF EVIDENCE

III, case-control study.

Influence of clinical and radiological variables on the extent and distribution of periprosthetic osteolysis in total hip arthroplasty with a hydroxyapatite-coated multiple-hole acetabular component: a magnetic resonance imaging study

Polyethylene wear-induced osteolysis constitutes the most severe long-term complication of total hip arthroplasties (THA). Our aim was to assess through MRI the severity and growth pattern of osteolysis, as well as the influence clinical-radiographic variables exert. We analyzed 75 THA with an average evolution time of 13.67years. The implant was a titanium alloy, non-cemented, multiple-hole model with hydroxyapatite coating. Osteolysis was found with a peripheral pattern in 48 and a central pattern in 6; in 52 cases it was continuous, and in 4, isolated. Out of 118 screws, 20 exhibited lysis. There was a proportional correlation between osteolysis severity and wear rate with age, physical activity and acetabular abduction, as well as an association between said variables and peripheral and continuous patterns.

Hip resurfacing versus total hip arthroplasty: a systematic review comparing standardized outcomes

BACKGROUND

Metal-on-metal hip resurfacing was developed for younger, active patients as an alternative to THA, but it remains controversial. Study heterogeneity, inconsistent outcome definitions, and unstandardized outcome measures challenge our ability to compare arthroplasty outcomes studies.

QUESTIONS/PURPOSES

We asked how early revisions or reoperations (within 5 years of surgery) and overall revisions, adverse events, and postoperative component malalignment compare among studies of metal-on-metal hip resurfacing with THA among patients with hip osteoarthritis. Secondarily, we compared the revision frequency identified in the systematic review with revisions reported in four major joint replacement registries.

METHODS

We conducted a systematic review of English language studies published after 1996. Adverse events of interest included rates of early failure, time to revision, revision, reoperation, dislocation, infection/sepsis, femoral neck fracture, mortality, and postoperative component alignment. Revision rates were compared with those from four national joint replacement registries. Results were reported as adverse event rates per 1000 person-years stratified by device market status (in use and discontinued). Comparisons between event rates of metal-on-metal hip resurfacing and THA are made using a quasilikelihood generalized linear model. We identified 7421 abstracts, screened and reviewed 384 full-text articles, and included 236. The most common study designs were prospective cohort studies (46.6%; n = 110) and retrospective studies (36%; n = 85). Few randomized controlled trials were included (7.2%; n = 17).

RESULTS

The average time to revision was 3.0 years for metal-on-metal hip resurfacing (95% CI, 2.95-3.1) versus 7.8 for THA (95% CI, 7.2-8.3). For all devices, revisions and reoperations were more frequent with metal-on-metal hip resurfacing than THA based on point estimates and CIs: 10.7 (95% CI, 10.1-11.3) versus 7.1 (95% CI, 6.7-7.6; p = 0.068), and 7.9 (95% CI, 5.4-11.3) versus 1.8 (95% CI, 1.3-2.2; p = 0.084) per 1000 person-years, respectively. This difference was consistent with three of four national joint replacement registries, but overall national joint replacement registries revision rates were lower than those reported in the literature. Dislocations were more frequent with THA than metal-on-metal hip resurfacing: 4.4 (95% CI, 4.2-4.6) versus 0.9 (95% CI, 0.6-1.2; p = 0.008) per 1000 person-years, respectively. Adverse event rates change when discontinued devices were included.

CONCLUSIONS

Revisions and reoperations are more frequent and occur earlier with metal-on-metal hip resurfacing, except when discontinued devices are removed from the analyses. Results from the literature may be misleading without consistent definitions, standardized outcome metrics, and accounting for device market status. This is important when clinicians are assessing and communicating patient risk and when selecting which device is most appropriate for individual patients.

10-year follow-up wear analysis of first-generation highly crosslinked polyethylene in primary total hip arthroplasty

Our goal was to report a 10-year follow up of linear penetration rates for HCLPE, and to determine whether a difference exists between penetrations measured on pelvis or hip anterior-posterior radiographs. We reviewed 48 total hip arthroplasties where a first-generation HCLPE liner was used. Femoral head penetration was measured on both AP pelvis and hip radiographs. Total wear and wear rate at 10 years were 1.26 mm and 0.122 mm/y, respectively. The rate decreased significantly after the first 2-3 years, plateauing at a wear rate of 0.05 mm/y for the last 5 years. The AP hip total wear and wear rate were 1.38 mm and 0.133 mm/y respectively, while rates were 1.13 mm and 0.109 mm/y respectively for the pelvis radiographs (P<.05). We found a significant difference in measurements of linear penetration when comparing AP pelvis vs. hip radiographs with lower rates recorded using an AP pelvis.

Low rate of dislocation of dual-mobility cups in primary total hip arthroplasty

BACKGROUND

Dual-mobility (DM) cups were introduced to minimize the risk of THA dislocation. The overall rate of dislocation of DM cups (including both large and small articulations) is controversial and ranges from 0% to 5% in previous studies.

QUESTIONS/PURPOSES

We therefore recorded (1) the dislocation rate, (2) loosening and osteolysis, and (3) subsequent related revisions with DM cups.

METHODS

Between 1998 and 2003, 2480 primary THAs with DM cups were undertaken in 2179 patients. The mean age was 69 years (range, 19-94 years). This group underwent specific clinical and radiographic evaluation at a minimum followup of 0.17 years (mean, 7 years; range, 0.17-11 years) to assess dislocation, reoperation, osteolysis, and cup fixation.

RESULTS

There were 22 dislocations (0.88%): 15 dislocations of large articulations (0.6%), with two (0.08%) recurring but only one requiring revision (0.04%), and seven intraprosthetic small articulation dislocations (0.28%), all needing revision surgery. At last followup, mean Harris hip score was 91 (range, 60-100); 2439 cups (98%) showed no signs of loosening; and 141 patients (145 hips) had osteolysis (6%). Osteolysis and cup loosening were more frequent in patients younger than 50 years at the time of surgery. The 10-year survivorship considering revision for any reason was 93% (95% CI, 91%-95%).

CONCLUSIONS

DM cups had a low dislocation rate in primary THA, with a limited frequency of adverse effects. We recommend DM cups to minimize dislocation in populations at high risk for instability, but they should be avoided in younger, active patients at higher risk for osteolysis.

Relation between lower extremity alignment and proximal femur anatomy. Parameters during total hip arthroplasty

BACKGROUND

Lower extremity alignment correlates with native femoral offset. Eventual impact of the change in femoral offset induced by total hip arthroplasty (THA) on lower extremity alignment has not been documented.

HYPOTHESIS

THA significantly changes lower extremity alignment, and the change correlates with the change in femoral offset.

MATERIALS AND METHODS

We conducted a prospective study of 200 patients with primary hip osteoarthritis or avascular femoral head necrosis who underwent cementless THA. Pre-operative computed-tomography templating was performed and the femoral component was then custom-manufactured to replicate the native femoral anatomy. Mean age was 58 years (range, 28-83 years). Before and at least two years after THA, two observers who were not involved in the surgical procedures used standing antero-posterior long-leg radiographs to determine the mechanical axis of the lower-limb (hip-knee-ankle [HKA] angle), femoral offset, neck-shaft angle (NSA), and lower-limb length discrepancy (LLLD).

RESULTS

Mean values pre-operatively and at last follow-up were as follows: HKA angle, 179.2° ± 3.9° (range, 170.5° to 190.5°) and 177.7° ± 3.5°(range, 173° to 187°); LLLD, -0.7 mm (range, -30 mm to +25 mm) and +5.1 mm (range, -7 mm to +21 mm); NSA, 134° ± 7.5° (range, 100° to 124°) and 135° ± 4.2° (range, 124° to 146°); and femoral offset, 42 ± 7.8 mm (range, 24 mm to 68 mm) and 49 ± 7.5 mm (range, 33 mm to 70 mm). Although THA significantly altered lower-limb alignment, univariate and multivariate analyses showed no significant association between the change in HKA angle and the change in femoral offset.

DISCUSSION

Lower-limb alignment was significantly affected by THA, although the HKA angle changes were small. The small impact of THA on HKA angle values may be ascribable to efforts aimed at replicating the native femoral offset during arthroplasty, as well as to the limited sample size and to potential measurement errors related to the small size of the changes. Our results suggest that, provided careful attention is directed to replicating the native femoral offset, THA in patients with limited pre-operative anatomical abnormalities may have no major impact on the biomechanical parameters of the ipsilateral knee.

LEVEL OF EVIDENCE

Level III, prospective diagnostic study.

Clinical outcome, survival and polyethylene wear of an uncemented total hip arthroplasty: a 10- to 12-year follow-up study of 81 hips

A complete 10- to 12-year follow-up of an uncemented total hip arthroplasty (THA) was performed regarding survival, clinical outcome, polyethylene wear and influencing factors on wear. Seventy-two patients (75 Mallory Head uncemented THA) with primary osteoarthritis operated on in 1999 or 2000 were included in the survival study. Mean age at the time of operation was 57.9 years (range 37-70). The survival rate after 11.9 years was 96% (95% CI 0.89-1.01). In three cases the acetabular component was revised because of extensive polyethylene wear. Fifty-four patients with 57 THAs were available for clinical and radiological analysis. At a mean follow-up time of 10.7 years (range 10-12) the clinical outcome can be considered comparable to other uncemented THA. Mean polyethylene wear was 1.8mm (range 0.4-3.8) with an annual wear rate of 0.15 mm/y. There was a significant correlation between polyethylene wear and inclination of the cup as well as male gender.

Survival analysis of total knee arthroplasty at a minimum 10 years' follow-up: a multicenter French nationwide study including 846 cases

INTRODUCTION

Survivorship for modern total knee arthroplasties (TKA) is not precisely known from large series, other than registries. The present retrospective study therefore analyzed 846 TKAs at a minimum 10 years' follow-up.

HYPOTHESIS

Ten-year survivorship for TKAs in a multicenter study exceeds 90%, independently of design and level of prosthetic constraint.

MATERIALS AND METHODS

Eight hundred and twenty-eight patients (846 TKAs) were assessed on the Knee Society score. Mean age was 71 years (range, 41-93 years); 274 males and 554 females (67%); 496 patients (60%) were active; diagnosis was principally osteoarthritis (n=752 [89%]). Most TKAs were cemented (n=704 [83%]), replacing the patella (n=668 [79%]) and sacrificed the posterior cruciate ligament (PCL) (n=707 [84%]), 65% being posterior-stabilized and 35% ultracongruent, with fixed (39%) or mobile bearing (61%).

RESULTS

At a minimum 10 years' follow-up, mean knee score rose from 35 (15-55) to 83 points (74-95), and functional score from 24 (5-45) to 74 points (60-90); mean flexion rose from 105° (25-125°) to 112° (25-125°). Mean hip-knee-ankle angle was 179.5° (169-189°). Sixty-three (7.5%) revision surgeries were required, mainly for loosening (n=18 [2%]) or infection (n=18 [1.8%]). Overall 10-year survivorship was 92% (95% CI: 0.90-0.94). There was no significant difference in survivorship according to implant design or PCL retention. Activity level correlated with revision rate; mechanical complications were more frequent in active and infectious complications in sedentary subjects. Revision was not more frequent in TKA aligned outside the 177-183° range.

DISCUSSION

Ten-year TKA survivorship was 92%, independently of design and level of mechanical stress. Revision was mainly for infection or loosening, and not for greater than 3° axis misalignment. Mechanical complications were more frequent in younger and more active subjects, for whom therefore other treatment options or technical improvements should be sought.

LEVEL OF EVIDENCE

Level IV. Retrospective study.

Influence of surgical approach on postoperative femoral bone remodelling after cementless total hip arthroplasty

We retrospectively evaluated the femoral periprosthetic bone mineral density (BMD) in a consecutive series of patients who had undergone total hip arthroplasty (THA) with a straight, double tapered cementless stem using a muscle-sparing anterolateral (group A) and the transgluteal (group B) surgical approach. Dual-energy x-ray absorptiometry (DXA) measurements were performed in the first postoperative week (t1), and after 3 (t2), 6 (t3) and 12 months (t4) using an identical protocol. Patients were clinically and radiographically evaluated at final follow-up (t4). A complete set of four consecutive DXA measurements was obtained for 16 hips in group A and 26 hips in group B. In patients in whom the transgluteal approach was used (Group B), we observed a significantly greater decline in overall periprosthetic BMD (netavg) and in BMD in the periprosthetic regions of interest (ROI) 1, 4, 5 and 6 between t1 and t4. At clinical and radiographic evaluation at t4, no differences between the groups were detected. Femoral periprosthetic BMD is affected by the selected surgical approach in the first postoperative year. This might be attributed to altered femoral loading as a result of differences in intraoperative damage to the abductor muscles.

Cemented versus uncemented fixation in total hip replacement: a systematic review and meta-analysis of randomized controlled trials

The optimal method of fixation for primary total hip replacements (THR), particularly fixation with or without the use of cement is still controversial. In a systematic review and metaanalysis of all randomized controlled trials comparing cemented versus uncemented THRS available in the published literature, we found that there is no significant difference between cemented and uncemented THRs in terms of implant survival as measured by the revision rate. Better short-term clinical outcome, particularly an improved pain score can be obtained with cemented fixation. However, the results are unclear for the long-term clinical and functional outcome between the two groups. No difference was evident in the mortality and the post operative complication rate. On the other hand, the radiographic findings were variable and do not seem to correlate with clinical findings as differences in the surgical technique and prosthesis design might be associated with the incidence of osteolysis. We concluded in our review that cemented THR is similar if not superior to uncemented THR, and provides better short term clinical outcomes. Further research, improved methodology and longer follow up are necessary to better define specific subgroups of patients in whom the relative benefits of cemented and uncemented implant fixation can be clearly demonstrated.

Recurrence of dislocation following total hip arthroplasty revision using dual mobility cups was rare in 180 hips followed over 7 years

BACKGROUND

Dual mobility (DM) cups of mobile polyethylene were introduced to prevent total hip arthroplasty (THA) dislocation, but no large series with this design to treat recurrent instability have been reported.

PURPOSE

Our retrospective investigation ascertained the efficiency of DM cups in correction of recurrent dislocation and assessed any adverse effects.

METHODS

One hundred eighty THAs with recurrent instability were revised to DM cups in 180 patients (mean age, 67.4 ± 11.7 years; range, 19 to 92 years). Thirty-one patients (17.2%) underwent at least one earlier THA revision, and 15 (10.3%) incurred non-union of the greater trochanter. Of the initial group in 2009, 145 patients had completed evaluations which included assessment of the Harris Hip Score and a radiographic assessment at a mean follow-up of 7.7 ± 2.2 years (range, 4 to 14 years). The rate of survival was calculated considering any reason for revision as failure.

RESULTS

At follow-up, Harris hip score was 83.9 ± 16.1 (range, 21 to 100). Dislocation of the large articulation occurred in seven hips (4.8%), and only two recurred (1.4%) (one requiring additional revision). In addition, two intra-prosthetic dislocations of the small articulation (1.4%) were observed and needed revision surgery. The large number of earlier surgeries and non-union of the greater trochanter were related to recurrent instability. Two cups (1.4%) showed signs of definite loosening; six (4.1%) presented signs of possible loosening. Twenty-nine hips manifested femoral or acetabular osteolysis (20%), but only three were severe. Eight-year survival rate considering revision for any reason was 92.6% (95% CI, 85.5-96.4%).

CONCLUSIONS

This series indicates that DM cups are a viable option to treat recurrent THA instability. Their design provides a low risk of recurrent instability without increasing mechanical complications.

Long-term results of cementless femoral reconstruction following intertrochanteric osteotomy

PURPOSE

The objective of this retrospective cohort study was to assess the long-term outcome of cementless femoral reconstruction in patients with previous intertrochanteric osteotomy (ITO).

METHODS

We evaluated the clinical and radiographic results of a consecutive series of 45 patients (48 hips, mean age 50 years) who had undergone conversion hip replacement following ITO with a cementless, grit-blasted, double-tapered femoral component. Clinical outcome was determined using the Harris hip score. Stem survival for different end points was assessed using Kaplan-Meier survivorship analysis.

RESULTS

At a mean follow-up of 20 (range, 16-24) years, 11 patients (12 hips) had died, and no patient was lost to follow-up. Six patients (six hips) underwent femoral revision, two for infection, three for aseptic loosening and one for periprosthetic fracture. Mean Harris hip score at final follow-up was 78 points (range, 23-100 points). Stem survival for all revisions was 89% (95%CI, 75-95) at 20 years, and survival for aseptic loosening was 93% (95%CI, 80-98).

CONCLUSIONS

The long-term results with this type of cementless femoral component in patients with previous intertrochanteric osteotomy are encouraging and compare well to those achieved in patients with normal femoral anatomy.

Straight tapered titanium stem with alumina bearing in cementless primary total hip arthroplasty: a minimum 5-year follow-up

The aim of this study was to assess the midterm results of primary cementless total hip arthroplasty using a tapered stem and alumina bearing couple in active patients. After a minimum of 5 years of follow-up, 78 arthroplasties in 72 patients were reviewed retrospectively. The mean Harris hip score was 94 points, and 2 hips had thigh pain. All components radiographically demonstrated stable fixation by bone ingrowth and mild stress shielding of the proximal femur were noted in 14% of hips. There was no significant osteolysis or aseptic loosening. There was a ceramic head fracture in 1 hip and audible sounds in 2 hips. The results of total hip arthroplasty with a straight, tapered, proximally porous-coated stem and alumina-on-alumina bearing were encouraging for active patients.

Bone remodeling around stable uncemented titanium stems during the second decade after total hip arthroplasty: a DXA study at 12 and 17 years

In a cohort study, bone mineral density (BMD) around uncemented femoral components after total hip arthroplasty (THA) was evaluated. The results suggest that there are no clinically relevant changes in overall periprosthetic BMD in the second decade. However, continuous remodeling with limited proximal bone loss (stress-shielding) occurs, predominantly in female patients.

INTRODUCTION

Progressive periprosthetic bone loss and stress-shielding are a major concern in THA. Little is known about the extent and pattern of periprosthetic bone remodeling around uncemented stems in the second decade.

METHODS

In a cohort study, periprosthetic BMD was measured in 131 patients with 146 uncemented CLS stems using dual-energy X-ray absorptiometry (DXA) at a mean of 12 years postoperatively (t1). Patients were followed clinically and radiographically, and a second DXA was performed at a mean of 17 years postoperatively (t2) using the identical protocol.

RESULTS

We obtained a complete set of two consecutive DXA measurements for 88 hips (78 patients, 35 male, 43 female). On radiographic evaluation at t1 and t2, regular bone ongrowth was present in all cases and no signs of radiographic loosening, severe bone loss or diaphyseal cortical hypertrophy were detected. There was no clinically relevant change in overall periprosthetic BMD (netavg) between t1 and t2 for both male and female patients. We analyzed the differences in BMD in the periprosthetic regions of interest (ROIs) according to Gruen and found a slight decrease in periprosthetic BMD in ROI 7 in male patients and in ROIs 1, 4, 6 and 7 in female patients.

CONCLUSIONS

The study suggests that there are no clinically relevant changes in overall periprosthetic BMD around stable, straight uncemented stems between 12 and 17 years postoperatively. However, continuous remodeling with limited proximal bone loss occurs, predominantly in female patients. After secondary osteointegration of this implant, stress-shielding remains minimal in the second decade.

Mid-term results of total hip arthroplasty with the CementLess Spotorno (CLS) system

BACKGROUND

Except for those reported by the designers, there are no published mid-term results of the use of the CementLess Spotorno (CLS) Total Hip Arthroplasty system. We present the results of (1) a ten to seventeen-year follow-up prospective cohort study of this system, and (2) retrospective analyses of factors influencing clinical and radiographic outcomes.

METHODS

We studied a series of 102 consecutive CLS arthroplasties with a minimal duration of follow-up of ten years. Indications for the procedures were osteoarthritis (n = 90), rheumatoid arthritis (n = 8), and femoral head osteonecrosis (n = 4). The Merle d'Aubigné-Postel score, polyethylene wear, and radiographic status were recorded at regular intervals. Survival analyses, repeated-measures analysis of variance, and a nested case-control study (with the cases having early revision due to aseptic cup loosening within ten years after the index procedure and the controls having no early cup revision) were used for evaluation.

RESULTS

There were fourteen revisions, including nine due to aseptic cup loosening. The ten-year Kaplan-Meier survival rate was 92.2% (95% confidence interval [CI] = 86.9 to 97.5) with revision for any reason as the end point. The fifteen-year survival rate was 78.4% (95% CI = 63.9 to 92.9) with revision for any reason as the end point, 81.6% (95% CI = 66.7 to 96.5) with revision due to aseptic cup loosening as the end point, and 99.0% (95% CI = 97.0 to 100.0) with revision due to aseptic stem loosening as the end point. The average amount of polyethylene wear at the time of final follow-up was 1.92 mm (range, 0.6 to 4.3 mm). The wear rate in the cases was significantly higher than that in the controls (0.31 vs. 0.16 mm/yr, p < 0.001). Factors with a significant effect on polyethylene wear were age at surgery (a 0.3-mm increase per every ten years younger, p = 0.001) and a larger head component (an effect of 0.53 mm for the 32 vs. the 28-mm component; p < 0.0001). Male sex had an effect of -0.66 point (p = 0.07) on the final Merle d'Aubigné-Postel score.

CONCLUSIONS

The results of this CLS system, particularly with regard to the femoral stem, are comparable with those with other reliable cementless systems. Nevertheless, the prevalence of aseptic acetabular cup loosening in the second decade after the operation demonstrates a potentially substantial problem with regard to long-term survival. A high polyethylene wear rate, male sex, a younger age at the time of surgery, and a 32-mm head component size are related to inferior clinical outcomes and a higher risk of implant revision.

In vivo polyethylene wear of bilateral total hip replacements - cemented versus uncemented modular sockets

We assessed polyethylene wear and osteolysis in 15 patients (30 hips) undergoing staged bilateral total hip arthroplasties, who had a cemented arthroplasty on one side and a hybrid arthroplasty on the other. All factors apart from mode of acetabular component fixation were matched. Wear was measured radiographically using Livermore's technique. The mean clinical and radiological follow-up was 11.2 years for the cemented and 10.7 years for the hybrid arthroplasties. Mean annual linear wear rate was 0.09mm/year in the cemented sockets and 0.14mm/year in the uncemented sockets. This difference was statistically significant (p=0.03), confirming previous reports that the rate of polyethylene wear is increased in uncemented sockets. No periacetabular osteolysis was noted. Femoral osteolysis in zone 7 occurred in 3 hybrid arthroplasties. It appears not all patients are equally affected. These results are further discussed.

Is there evidence for a superior method of socket fixation in hip arthroplasty? A systematic review

PURPOSE

Total hip arthroplasty has been a very succesful orthopaedic procedure. The optimal fixation method of the acetabular component however, has not yet been defined.

METHODS

We performed a systematic review using the Medline and Embase databases to find evidence for the superiority of cemented or cementless acetabular components on short- and long-term clinical and radiological parameters. Methodological quality for randomised trials was assessed using the van Tulder checklist, and for the non randomised studies we used the Newcastle-Ottawa quality assessment scale.

RESULTS

Our search strategy revealed 16 randomised controlled trials (RCT) and 19 non RCT studies in which cemented and cementless acetabular components are compared. A best evidence analysis for complications, wear, osteolysis, migration and clinical scores showed no superiority for either cemented or cementless socket in the RCTs. A best evidence analysis for non RCT studies revealed better osteolysis, migration properties and aseptic loosening survival for cementless sockets; however, wear and overall survival favoured the cemented sockets.

CONCLUSIONS

We recommend that an orthopaedic surgeon should choose an established cemented or cementless socket for hip replacement based on patient characteristics, knowledge, experience and preference.

Long term survival of an hydroxyapatite-coated threaded cup in the presence of a high polythene wear rate

We describe the long term clinical results and polythene wear rate measurement of 144 uncemented total hip arthroplasties in 118 patients (Male: Female-65: 53, Mean age: 52.8 years (range 21-78 years) performed between 1988 and 2000 using the Furlong HAC coated threaded acetabular cup. The mean follow-up for the group was 10.2 years (range: 5-17.5, median: 9.7). One femoral stem and two acetabular shells were revised due to aseptic loosening. The mean polythene wear rate was 0.24 mm/year. Ten-year survival for the acetabular and femoral components with radiological evidence of aseptic loosening as an end point was 99.15 (CI: 98.3-99.9) and 99.28 (CI: 98.5-99.9). There was no evidence of osteolysis around the femoral or acetabular components in spite of a relatively high polythene wear rate (0.24 mm/year). Our study demonstrates excellent survival of threaded HAC coated acetabular sockets at 10 years in spite of a relatively high polythene wear rate.

Mid- to long-term outcome of cementless total hip arthroplasty in younger patients

PURPOSE

To assess mid- to long-term outcomes of cementless primary total hip arthroplasty (THA) in younger patients.

METHODS

Records of 28 women and 34 men (75 hips) aged 18 to 55 (mean, 38) years who underwent primary THA using a hydroxyapatite-coated stem and a threaded cup and had been followed up for a mean of 10 (6-15) years were reviewed. 13 of the patients had bilateral THAs. Clinical and radiographic outcomes were evaluated.

RESULTS

After a minimum follow-up of 7 (range, 7-14) years, 12 (16%) of the hips were revised, of which 8 (11%) were for the cup. The causes for revision were late deep infections (n=2), aseptic loosening of the cup (n=4), and polyethylene wear (n=6). No stem was revised for aseptic loosening. Osteolysis was noted in 24 (38%) hips. Of the 63 unrevised hips, the mean Harris Hip Score was 92 (range, 45-100) and the mean D'Aubigne and Postel score was 17 (range, 9-18). The survival of the threaded cup was 88% at 10 years, using revision surgery as the end point. 27 (41%) of the hips showed signs of polyethylene wear; 15 were >2 mm.

CONCLUSION

In younger patients undergoing THA, rates of polyethylene wear and pelvic osteolysis are high, and thus long-term follow-up is crucial.

A new radiographic method of measuring femoral offset. The Sundsvall method

Restoring femoral offset (FO) is an important factor for the success of total hip arthroplasty (THA). However, earlier methods of measuring FO do not take in consideration the positioning of the acetabular component. In this study we introduce and evaluate a new radiological method of measuring FO as the horizontal distance between the femoral axis and the midline of the pelvis, at the height of the lateral tip of the greater trochanter.Ten patients operated with THA underwent a plain radiographic examination of the pelvis (AP view) and a CT scanogram for the pelvis and lower limbs (scout view). The radiological FO measurement using the new method was initially compared to FO measurement on CT scanogram and subsequently to the traditional radiological method of measuring FO. We tested the interobserver reliability and the intraobserver reproducibility of the new method.We found an excellent agreement between the new radiological method and the CT measurement and between the new radiological method and the traditional radiological method. We also found an excellent interobserver reliability and an intraobserver reproducibility of the new method. We believe the new method is easier than and as reliable as previously described methods.

2009 Nicolas Andry Award: clinical biomechanics of third body acceleration of total hip wear

Aseptic loosening attributable to wear-related osteolysis historically has been the predominant cause of failure in THA. Advances in low-wear bearing couples show great promise to substantially reduce this long-standing problem. However, there always has been striking variability in wear rate in any given cohort of patients who are similarly implanted, with some individuals typically experiencing near order-of-magnitude elevations above group mean. Third-body wear is likely a major contributor to many of these most osteolysis-prone outliers. For the patients affected, third-body effects may obviate many of the gains otherwise achieved by contemporary bearing surface improvements. Toward heightening visibility in terms of consequences for patients, this review paper summarizes an interrelated series of investigations quantifying construct level manifestations of third-body wear. Long-term followup of a unique group of patients with elevated third-body challenge shows statistically significant and clinically important wear-rate increases. A series of finite element models, validated physically, shows the linkage of location of third-body damage with variability of volumetric wear-rate acceleration and shows the effects of various implant factors, surgeon factors, and patient factors in the presence of third-body challenge. Finally, a mechanism for third-body debris access to wear-critical locations on the bearing surface is identified analytically and corroborated in laboratory experiments and implant retrievals.

Uncemented grit-blasted straight tapered titanium stems in patients younger than fifty-five years of age. Fifteen to twenty-year results

BACKGROUND

Total hip arthroplasty without cement is frequently performed in young active patients, but only limited outcomes data are available after durations of follow-up of more than fifteen years.

METHODS

We retrospectively evaluated the clinical and radiographic results of a consecutive series of 154 total hip arthroplasties (in 141 patients) performed with an uncemented grit-blasted straight tapered titanium femoral stem combined with a threaded socket in patients under the age of fifty-five years. The median duration of follow-up was seventeen years. Clinical results were evaluated with use of the Harris hip score. The canal fill index was used as the criterion to determine the adequacy of stem sizing. Kaplan-Meier survivorship analysis was performed to predict long-term outcomes.

RESULTS

The stem was undersized, with a canal fill index of < or =80%, in forty-one hips (27%). Late aseptic loosening of the stem occurred in four femora, and the femoral component was undersized in all four. These four stems were stable for ten years and then underwent progressive subsidence, which was associated with pain. Five stems were revised because of a late postoperative periprosthetic fracture following trauma. Localized proximal femoral osteolysis was seen in seven hips without signs of loosening. Survivorship of the stem with revision for any reason as the end point was estimated to be 90% (95% confidence interval, 87% to 97%) at twenty years. Survivorship with aseptic loosening as the end point was estimated to be 95% (95% confidence interval, 91% to 99%) at twenty years. Sixty-seven (44%) of the threaded uncemented acetabular components were revised during the follow-up period.

CONCLUSIONS

After a minimum duration of follow-up of fifteen years, the survival of this type of femoral component is excellent in individuals younger than fifty-five years. The main mode of stem failure was a periprosthetic fracture due to trauma, or late aseptic loosening in a small percentage of the hips in which the femoral implant was undersized. The high rate of failure of the acetabular components was attributable to a poor design that is no longer in use.

Massive wear and metallosis of an Acetabular Cup System presenting as pseudodislocation

In primary and revision total hip arthroplasty (THA), the acetabular component continues to pose greater challenges than the femoral component. Numerous factors lead to polyethylene wear, which subsequently affects primary THA survival. Progressive polyethylene wear is associated with the occurrence of osteolysis, especially overlying the acetabulum, which can lead to component loosening and subsequent revision. Polyethylene failure usually manifests as massive liner wear up to the metal shell, fracture of the liner, or a combination of both. There is often a small amount of metallosis associated with this pathology. To our knowledge, massive wear of the acetabular metal shell, however, has not previously been reported in the literature. This article describes a case of massive wear through a polyethylene liner and the acetabular metal shell of an Acetabular Cup System (DePuy, Leeds, United Kingdom) that presented as an apparent dislocation 13 years following the index operation. The pseudodislocation was intraoperatively found to be penetration of the femoral head through the acetabular shell. The acetabular component was consequently revised to a larger cementless cup. The femoral component was mechanically stable and required no revision. Patients with long-standing Acetabular Cup System THA may experience acetabular metal shell wear-through phenomena presenting as a pseudodislocation, and this possibility should be taken into consideration during preoperative planning.

Risk factors for revision for early dislocation in total hip arthroplasty

Risk factors were investigated for revision for dislocation in primary total hip arthroplasties (THAs) between September 1, 1999, and December 31, 2004, as reported by the Australian Orthopaedic Association National Joint Replacement Registry. For 65992 primary THAs, the only initial diagnoses with significantly increased relative risk (RR) of revision for dislocation compared to osteoarthritis were fractured neck of femur (RR, 2.03; P < .001), rheumatoid arthritis (RR, 2.01; P < .01), and avascular necrosis (RR, 1.57; P < .05). A total of 58109 primary THAs for osteoarthritis were investigated for effect of age group, sex, and fixation method. There were 428 (0.7%) revisions for dislocation, 369 (0.8%) with a cementless acetabulum, and 59 (0.6%) with cemented acetabulum (RR, 1.59; P < .01). There is a significantly increasing risk of revision for dislocation as head size decreases (P < .001). Cementless acetabula, particularly with smaller heads, have a higher rate of revision for dislocation.

Activity levels and polyethylene wear of patients 10 years post hip replacement

BACKGROUND

Wear of the acetabular cup and implant loosening in total hip arthroplasty are thought to be affected by individual patient activity levels.

METHODS

Activity levels of 100 patients with unilateral primary hip replacements were measured using a digital pedometer 10-years post-operatively.

FINDINGS

Activity rates of hip replacement patients 10 years post surgery were found to fall with increasing age strata, with the age group 70-74 years showing significantly reduced activity rates compared to the 55-64 years age group and the age group greater than 80 years showing significantly reduced activity rates compared to both the 55-64 years age group and the 65-69 years age group. However, a clear correlation between age and activity was not found. Acetabular cup wear showed no relationship with patient activity levels.

INTERPRETATION

Progressive reduction in activity levels with more elderly hip replacement patients may inform long term planning of hip arthroplasty and implant choice.

Advanced nanocomposite materials for orthopaedic applications. I. A long-term in vitro wear study of zirconia-toughened alumina

The use of ceramic-on-ceramic (alumina- and zirconia-based) couplings in hip joint prostheses has been reported to produce lower wear rates than other combinations (i.e., metal-on-polyethylene and ceramic-on-polyethylene). The addition of zirconia into an alumina matrix (zirconia-toughened alumina, ZTA) has been reported to result in an enhancement of flexural strength, fracture toughness, and fatigue resistance. The development of new processing routes in nonaqueous media has allowed to obtain high-density ZTA nanocomposites with a very homogeneous microstructure and a significantly smaller and narrower particle-size distribution of zirconia than conventional powder mixing methods. The aim of the present study was to set up and validate a new ZTA nanocomposite by testing its biocompatibility and wear behavior in a hip-joint simulator in comparison with commercial alumina and experimental alumina specimens. The primary osteoblast proliferation onto ZTA nanocomposite samples was found to be not significantly different from that onto commercial alumina samples. After 7 million cycles, no significant differences were observed between the wear behaviors of the three sets of cups. In this light, it can be affirmed that ZTA nanocomposite materials can offer the option of improving the lifetime and reliability of ceramic joint prostheses.

Patient sensitivity to polyethylene particles with cemented total hip arthroplasty

To determine whether sensitivity to polyethylene particles varies among patients, we studied 25 patients who had undergone total hip arthroplasty. We used pelvic radiographs to measure annual polyethylene wear and the area of osteolysis. The ratio of the area of osteolysis to the volumetric polyethylene wear was defined as sensitivity index. Adherent cells from peripheral blood were cocultured with polyethylene particles, and the amount of bone-resorptive cytokines was measured. The amount of interleukin-6, but not of interleukin-1beta or tumor necrosis factor-alpha, released from adherent cells in the in vitro experiment correlated with the in vivo sensitivity indices. This technique appears capable of predicting the development of polyethylene-induced osteolysis, allowing surgeons to avoid using polyethylene as the bearing surface in patients at risk for osteolysis.

Polyethylene sterilization and production affects wear in total hip arthroplasties

Production and package sterilization techniques for the polyethylene used in acetabular components for total hip arthroplasties are known to affect wear. We considered three combinations of techniques: sterilization by radiation in inert gas with isostatically molded polyethylene, in inert gas and ram-extruded polyethylene, and in air with extruded polyethylene. The intent of this study was to confirm that molded polyethylene and polyethylene radiated in inert environments reduce wear rates in vivo, to determine the combination of methods with the least wear, and to determine how much variance in wear is attributable to these methods. We reviewed 150 consecutive total hip arthroplasties done in 133 patients using 28-mm cobalt-chrome femoral heads and polyethylene-lined, titanium, ring-locked acetabular components. The least wear occurred in gamma inert-molded polyethylene components. The mean volumetric wear rates were 52.12 mm3/year for gamma inert-molded, 62.32 mm3/year for gamma inert-extruded, and 66.09 mm3/year for gamma air-extruded polyethylene components. Relative risk assessment found gamma air-extruded and gamma inert-extruded polyethylene components to wear 16% and 11% more than gamma inert-molded polyethylene components, respectively. Gender, body mass index, and age accounted for the greatest amount of the explained variance in volumetric wear (57.5%, 21.6%, and 14.4, respectively), followed by angle of wear (3.4%), and sterilization and production technique (3.2%).

Biomechanical reconstruction of the hip: a randomised study comparing total hip resurfacing and total hip arthroplasty

We have compared the biomechanical nature of the reconstruction of the hip in conventional total hip arthroplasty (THA) and surface replacement arthroplasty (SRA) in a randomised study involving 120 patients undergoing unilateral primary hip replacement. The contralateral hip was used as a control. Post-operatively, the femoral offset was significantly increased with THA (mean 5.1 mm; -2.8 to 11.6) and decreased with SRA (mean -3.3 mm; -8.9 to 8.2). Femoral offset was restored within sd 4 mm in 14 (25%) of those with THA and in 28 (57%) of the patients receiving SRA (p < 0.001). In the THA group, the leg was lengthened by a mean of 2.6 mm (-6.04 to +12.9), whereas it was shortened by a mean of 1.9 mm (-7.1 to +2.05) in the SRA group, compared with the contralateral side. Leg-length inequality was restored within sd 4 mm in 42 (86%) of the SRA and 33 (60%) of the THA patients. The radiological parameters of acetabular reconstruction were similar in both groups. Restoration of the normal proximal femoral anatomy was more precise with SRA. The enhanced stability afforded by the use of a large-diameter femoral head avoided over-lengthening of the limb or increased offset to improve soft-tissue tension as occurs sometimes in THA. In a subgroup of patients with significant pre-operative deformity, restoration of the normal hip anatomy with lower pre-operative femoral offset or significant shortening of the leg was still possible with SRA.

Does pelvic osteolysis occur with a nonmodular uncemented acetabular component?

We present a radiographic follow-up of an uncemented, nonmodular, pure titanium-backed acetabular component at 6 to 12 years postimplantation. Between 1990 and 1992, 130 primary total hip arthroplasties were carried out by 1 surgeon using this implant, in association with both cemented and uncemented femoral components. There were 19 deaths, 5 revisions, and 19 hips lost to follow-up, leaving 87 hips available for review at a mean of 9.6 years. Two revisions were for infection, whereas 3 well-fixed cups were changed at the time of revision of a loose femoral component to allow downsizing to a 28-mm head. No cup has been revised for aseptic loosening. There was no radiographic evidence of periacetabular osteolysis or loosening of any of the cups, even in a subgroup of 31 patients who were 60 years or younger at the time of implantation.

In vivo comparative wear study of traditional and highly cross-linked polyethylene in total hip arthroplasty

In this study, we compare the in vivo wear performance of electron beam-irradiated, postirradiation-melted, highly cross-linked polyethylene (HXLPE) and traditional UHMWPE via the Martell method. Seventy hips with HXLPE performed at the Massachusetts General Hospital had 138 radiograph pairs for wear analysis and a 31.2-month average follow-up (range, 24-44 months). An age-matched, sex-matched, and body mass index-matched subgroup of 111 hips with 214 acceptable radiograph pairs and a 4-year follow-up from our previously published study on traditional polyethylene performed at Rush-Presbyterian-St. Luke's Medical Center served as a control group. Martell wear analysis was performed for each group. Overall and steady-state wear rates were compared via a specialized t test. The steady-state wear in the HXLPE arm was observed after 2.0 years, was 0.007 mm/y, and was significantly less than the steady-state wear in the traditional arm (0.174 mm/y) (P = .003). Highly cross-linked polyethylene penetration rate was not affected by sex, age, activity, or body mass index by Mann-Whitney analysis.

A new approach for the Martell 3-D method of measuring polyethylene wear without requiring the cross-table lateral films

Due to the uneven and often inadequate quality of cross-table lateral hip radiographs, many radiographic studies of femoral head penetration into polyethylene in total hip arthroplasty are limited to the two-dimensional measurement of femoral head penetration using the A/P film only. We postulated that the use of two oblique frontal projections at 90 degrees to each other would improve the three-dimensional evaluation. Using an established hip phantom, the idealized accuracy and precision of the three-dimensional Martell method was evaluated, contrasting the standard A/P and cross-table lateral projections versus a pair of oblique projections by four independent readers. Accuracy and precision resulting from the use of two oblique projections (average accuracy +/-63 microm, precision +/-26 microm) were similar to that obtained using the conventional A/P and cross-table lateral views (accuracy +/-54 microm, precision +/-22 microm), though the results of the two oblique views were slightly more variable. These observations suggest that by using two oblique A/P projections, the major disadvantage of using the cross-table lateral films, namely the variable quality of the images, is avoided. Perhaps, therefore, the utility and availability of three-dimensional data in comparable clinical studies may be improved.