Cemented Versus Cementless Femoral Fixation for Total Hip Arthroplasty Following Osteoarthritis.

BACKGROUND: The mode of femoral fixation for primary total hip arthroplasty (THA) is undetermined, with reported outcomes favoring different fixation methods. This study aimed to compare postoperative complications between cemented and cementless fixation at 90 days, 1 year, and 2 years in patients aged 65 years of age and older undergoing THA for osteoarthritis. METHODS: Using an all-payer, national database, patients 65 years and older undergoing primary THA, either with cementless (n = 56,701) or cemented (n = 6,283) femoral fixation for osteoarthritis were identified. A 1:1 propensity-matched analysis for age, sex, comorbidity index, alcohol abuse, tobacco use, obesity, and diabetes was performed, resulting in n = 6,283 patients in each cohort. Postoperative outcomes, including postoperative periprosthetic joint infection, aseptic revision, surgical site infection, pulmonary embolism, venous thromboembolism, wound complications, dislocation, periprosthetic fracture, and aseptic loosening were assessed. RESULTS: The cemented cohort had higher rates of infection (4.5 versus 0.8%, odds ratio [OR] 5.9, 95% confidence interval [CI] 4.33 to 7.93, P < .001), aseptic revision (2.9 versus 2.0%, OR 1.47, 95% CI 1.17 to 1.85, P = .001), venous thromboembolism (1.8 versus 1.3%, OR 1.40, 95% CI 1.05 to 1.87, P < .001), and aseptic loosening (1.5 versus 0.7%, OR 2.31, 95% CI 1.60 to 3.32, P < .001) at 90-days. At 1 and 2 years, the cemented cohort had higher rates of infection, aseptic revision, and aseptic loosening (all P < .001). Rates of periprosthetic fracture were similar at all time points (all P < .001). CONCLUSIONS: Cemented fixation had higher rates of infection, aseptic loosening, and aseptic revision. This finding supports the current use of cementless fixation, but the ultimate decision regarding fixation type should be based on the proper optimization of the patient's comorbidities and bone quality.

Genetically predicted obesity and risk of hip osteoarthritis.

OBJECTIVES: To determine the causal association between genetically predicted obesity and the risk of hip osteoarthritis. METHODS: We performed two-sample Mendelian randomization (MR) analysis to analyze the association between body mass index (BMI) and hip osteoarthritis using pooled-level genome-wide association study (GWAS) data. The inverse variance weighted (IVW), MR‒Egger, and weighted median methods were used to estimate the causal association. In addition, we applied the MR Steiger filtering method, MR robust adjusted profile score (MR.RAPS) methods, and the MR Pleiotropy RESidual Sum and Outlier (MR-PRESSO) global test to examine and address potential horizontal pleiotropy. RESULTS: We found a causal relationship between genetically predicted BMI and the risk of hip osteoarthritis by the IVW method [OR = 1.45, 95% confidence interval (CI) = 1.04-2.00, P = 0.02]. In the sensitivity analysis, the results of the MR‒Egger and weighted median methods revealed similar estimations but with a wide CI with lower precision. The funnel plot, MR-Egger intercept, and MR-PRESSO all indicated the absence of a directional pleiotropic effect. In addition, no heterogeneity was observed in the present analysis. Therefore, the result of IVW is most suitable and reliable for the present MR analysis. CONCLUSION: There is a causal relationship between obesity and a higher risk of hip osteoarthritis, suggesting that weight management may be an intervention for the prevention and management of hip osteoarthritis. LEVEL OF EVIDENCE: Bioinformatics, Basic science.

Comparison of mid-term clinical results between cementless and cemented femoral stems in total hip arthroplasty with femoral shortening osteotomy for Crowe type IV hips.

INTRODUCTION: This report is the first study to compare the clinical outcomes between cementless and cemented femoral prostheses in total hip arthroplasty (THA) with subtrochanteric femoral shortening osteotomy for Crowe type IV hips. MATERIALS AND METHODS: We identified 26 hips in 20 patients who had undergone cemented (n = 13) or cementless (n = 13) THA with subtrochanteric femoral shortening osteotomy for Crowe type IV hips with a minimum follow-up period of 2 years. The mean follow-up period was 60.8 ± 33.9 months (24-120 months). We compared radiological findings, postoperative clinical recoveries, postoperative complications, and implant survival rates. RESULTS: In both groups, there were no cases of aseptic loosening for the acetabular and femoral implant. In terms of bone union at the osteotomy site, the mean duration was significantly longer in the cemented group (9.8 ± 4.2 months) than in the cementless group (5.0 ± 1.9 months). The clinical hip score in gait and pain at 3 months postoperatively was significantly higher in the cemented group than in the cementless group, while there were no significant changes at other timepoints between two groups. The number of postoperative complications was not significantly different between the two groups. The implant survival rate was 92% in the cementless group and 100% in the cemented group at 5 years postoperatively (P = 0.31). CONCLUSIONS: The cemented femoral prosthesis is superior to the cementless femoral prosthesis for early clinical recovery, while the duration required to achieve bone union at the osteotomy site is longer in the cemented femoral prostheses. It is possible for surgeons to perform successful hip reconstructions, regardless of the fixation method used for THA with shortening femoral osteotomy.

Implant survival of 2,723 vitamin E-infused highly crosslinked polyethylene liners in total hip arthroplasty: data from the Finnish Arthroplasty Register.

Background and purpose - The use of crosslinked polyethylene in total hip arthroplasty (THA) has decreased wear remarkably. It has been suggested that the antioxidative effects of vitamin E may enhance the wear properties of polyethylene even further. This study evaluates revision rates between vitamin E-infused polyethylene liners (E1 and E-poly, ZimmerBiomet, Warsaw, IN, USA) versus moderately crosslinked polyethylene (ModXLPE) liners from the same manufacturer used in primary THA.Patients and methods - We conducted a study based on data from the Finnish Arthroplasty Register. The study group consisted of 2,723 THAs with a vitamin E-infused liner and a reference group of 2,707 THAs with a moderately crosslinked polyethylene liner. Survivorship, revision risk, and re-revision causes were compared between groups.Results - The 7-year survival of the vitamin E-infused polyethylene liner group and of the reference group with revision for any reason as the endpoint was comparable (94% [95% CI 92.9-94.9] and 93% [CI 91.9-93.9], respectively). The adjusted hazard ratio (HR) for any revision was similar between the groups (0.7 [CI 0.4-1.1]). When revision for aseptic loosening was studied as the endpoint, the survival for the study group was 99% (CI 98.6-99.4) and for the reference group 99% (CI 98.7-99.5), and the risk of revision was comparable between the study groups (HR 1.3 [CI 0.7-2.5]).Interpretation - After an observation period of 7 years vitamin E-infused liners shows results equal to results obtained with crosslinked polyethylene liners.

Similar early mortality risk after cemented compared with cementless total hip arthroplasty for primary osteoarthritis: data from 188,606 surgeries in the Nordic Arthroplasty Register Association database.

Background and purpose - Current literature indicates no difference in 90-day mortality after cemented compared with cementless total hip arthroplasty (THA). However, previous studies are hampered by potential selection bias and suboptimal adjustment for comorbidity confounding. Therefore, we examined the comorbidity-adjusted mortality up to 90 days after cemented compared with cementless THA performed due to osteoarthritis.Patients and methods - Using the Nordic Arthroplasty Register Association database, 2005-2013, we included 108,572 cemented and 80,034 cementless THA due to osteoarthritis. We calculated the Charlson comorbidity index of each patient based on data from national patient registers. The Kaplan-Meier method was used to estimate unadjusted all-cause mortality. Cox regression was used to estimate hazard ratios (HR) with 95% confidence intervals (CI) for 14, 30-, and 90-day mortality comparing cemented with cementless THA, adjusting for age, sex, comorbidity, nation, and year of surgery.Results - Cumulative all-cause mortality within 90 days was 0.41% (CI 0.37-0.46) after cemented and 0.26% (CI 0.22-0.30) after cementless THA. The adjusted HR for cemented vs. cementless fixation was 0.97 (CI 0.79-1.2), and similar risk estimates were obtained for mortality within 14 (adjusted HR 0.91 [CI 0.64-1.3]) and 30 days (adjusted HR 0.94 [CI 0.71-1.3]). We found no clinically relevant differences in mortality between cemented and cementless THA in analyses stratified by age, sex, Charlson comorbidity index, or year of surgery.Interpretation - After adjustment for comorbidity as an important confounder, we observed similar early mortality between the 2 fixation techniques.

Bowing-head sign: rare but detectable in pre-catastrophic hip implant failure.

Recently, catastrophic failure (i.e., dissociation between the metal femoral head and stem due to stem neck deformation) after total hip arthroplasty (THA) has been reported. Early detection of this complication is very important, because it is accompanied by an increased cobalt concentration in the body, which might influence systemic conditions such as heart failure and immune system diseases. However, early detection of stem neck deformation is considered as difficult. In most cases in the literatures, the diagnosis was made at the time of acute dissociation. We report a case of early detection of stem neck deformation with the 'Bowing-head sign' before acute dissociation. The patient is a 71-year old woman complained of a clicking sensation in the right hip during regular follow-up after THA with a 32-mm cobalt/chromium head with polyethylene insert for osteoarthritis performed 7 years previously. The plain radiograph showed that the angle between the metal femoral head and the axis of the stem neck was not perpendicular ('Bowing-head sign'). Dynamic evaluation under fluoroscopy showed movement of the stem neck in the metal femoral head with hip abduction and adduction. Laboratory data showed abnormal serum cobalt (6.3 µg/L, normal < 1 µg/L) and chromium (3.8 µg/L, normal < 5 µg/L) levels. Considering those radiographic findings, deformation of the stem neck due to trunnionosis was diagnosed, and elective revision surgery was performed without any complications. Plain radiographs after THA should be assessed with attention to this complication, 'Bowing-head sign' must not be overlooked.

Vitamin E-blended highly cross-linked polyethylene liners in total hip arthroplasty: a randomized, multicenter trial using virtual CAD-based wear analysis at 5-year follow-up.

BACKGROUND: Progressive oxidation of highly cross-linked ultra-high molecular weight (UHMPWE-X) liners is considered to be a risk factor for material failure in THA. Antioxidants such as vitamin E (alpha-tocopherol) (UHMWPE-XE) were supplemented into the latest generation of polyethylene liners. To prevent inhomogenous vitamin E distribution within the polymer, blending was established as an alternative manufacturing process to diffusion. The purpose of the present study was to investigate the in vivo wear behavior of UHMWPE-XE in comparison with conventional UHMWPE-X liners using virtual CAD-based radiographs. METHODS: Until now, 94 patients from a prospective, randomized, controlled, multicenter study were reviewed at 5-year follow-up. Of these, 51 (54%) received UHMWPE-XE and 43 (46%) UHMWPE-X liners. Anteroposterior pelvic radiographs were made immediately after surgery and at 1 and 5 years postoperatively. The radiographs were analyzed using the observer-independent analysis software RayMatch® (Raylytic GmbH, Leipzig, Germany). RESULTS: The mean wear rate was measured to be 23.6 µm/year (SD 13.7; range 0.7-71.8 µm). There were no significant differences between the two cohorts (UHMWPE-X: 23.2 µm/year vs. UHMWPE-XE: 24.0 µm/year, p = 0.73). Cup anteversion significantly changed within the 1st year after implantation independent from the type of polyethylene liner [UHMWPE-X: 18.2-23.9° (p = 0.0001); UHMWPE-XE: 21.0-25.5° (p = 0.002)]. No further significant changes of cup anteversion in both groups were found between year 1 and 5 after implantation [UHMWPE-X (p = 0.46); UHMWPE-XE (p = 0.56)]. CONCLUSION: The present study demonstrates that the addition of vitamin E does not adversely affect the midterm wear behavior of UHMWPE-X. The antioxidative benefit of vitamin E is expected to become evident in long-term follow-up. Cup anteversion increment by 5° within the 1st year is likely a result of the released hip flexion contracture resulting in an enhanced posterior pelvic tilt. Therefore, a reassessment of target values in acetabular cup placement might be considered.

Inferior stabilization of cementless compared with cemented dual-mobility cups in elderly osteoarthrosis patients: a randomized controlled radiostereometry study on 60 patients with 2 years' follow-up.

Background and purpose - Elderly patients may benefit from a dislocation low-risk dual-mobility (DM) articulation in total hip arthroplasty, but the best cup fixation method is unknown. We compared cup migration for cemented and cementless DM cups using radiostereometry.Patients and methods - In a patient-blinded randomized trial, 60 patients (33 female) with osteoarthritis were allocated to cemented (n = 30) or cementless (n = 30) Avantage DM cup fixation. Criteria were age above 70 years, and T-score above -4. We investigated cup migration, periprosthetic bone mineral density (BMD), and patient-reported outcome measures (PROMs) until 24 months postoperative follow-up.Results - At 24 months mean proximal cup migration was 0.11 mm (95% CI 0.00-0.23) for cemented cups and 0.09 mm (CI -0.09 to 0.28) for cementless cups. However, cementless cups generally migrated more than cemented cups at 12 and 24 months. Cemented cups had no measurable migration from 3 months' follow-up, while cementless cups had not yet stabilized at 24 months in all rotations. Cementless cups showed statistically significantly more maximum total point motion (MTPM) at 12- and 24-month follow-up compared with cemented cups in patients with low systemic BMD (p = 0.01). Periprosthetic BMD changes did not statisticially significantly correlate to proximal migration in either cup fixation group (p > 0.05). PROMs improved similarly in both groups.Interpretation - Cemented cups were well fixed at 3 months. The cementless cups migrated more in patients with low BMD, showed an inconsistent pattern of migration, and migrated in different directions during the first and second year without tendency to stabilization. Cemented fixation of the Avantage DM cup seems safer in elderly patients.

Higher early proximal migration of hemispherical cups with electrochemically applied hydroxyapatite (BoneMaster) on a porous surface compared with porous surface alone: a randomized RSA study with 53 patients.

Background and purpose - BoneMaster (BM) is an electrochemically deposited hydroxyapatite (HA) implant-coating, which is evenly distributed, thin, and quickly resorbed. It is designed to stimulate osseointegration and early implant stability and alleviate longer-term HA-induced third-body polyethylene wear. This study evaluates early cup migration and functional outcomes of cementless porous-coated hemispherical cups with or without BM.Patients and methods - In a patient-blinded, randomized, controlled trial 53 patients at mean 64 years (55-75) with coxarthritis were operated with an Exceed cup (Zimmer Biomet) and Bi-Metric stem (Zimmer Biomet) with porous and BM coating (PBM) or with porous coating alone (P). Follow-ups were performed postoperatively and at 3, 6, 12, and 24 months. Effect measures were cup migration measured with RSA and PROMs.Results - At 6-month follow-up, proximal cup migration in the PBM group (0.09 mm, 95% CI 0.02-0.20) was higher than in the P group (0.25 mm, CI 0.15-0.35). At 1- and 2-year follow-up, cup migration in all 6 degrees of freedom was similar between groups (p > 0.2). From before surgery to 2-year follow-up, Oxford Hip Score (OHS) increased by 17 points (CI 14-20). Hip disability and Osteoarthritis Outcome Score (HOOS) increased in all sub-scores, but was more pronounced for PBM cups compared with P cups in the Symptoms sub-score (p = 0.04).Interpretation - Contrary to expectations, PBM cups had higher early migration than P cups. At 2-year follow-up, migration was similar between groups. There seems to be no early benefit of BM coating on acetabular cups.

Perioperative, short-, and long-term mortality related to fixation in primary total hip arthroplasty: a study on 79,557 patients in the -Norwegian Arthroplasty Register.

Background and purpose - There are reports on perioperative deaths in cemented total hip arthroplasty (THA), and THA revisions are associated with increased mortality. We compared perioperative (intraoperatively or within 3 days of surgery), short-term and long-term mortality after all-cemented, all-uncemented, reverse hybrid (cemented cup and uncemented stem), and hybrid (uncemented cup and cemented stem) THAs.Patients and methods - We studied THA patients in the Norwegian Arthroplasty Register from 2005 to 2018, and performed Kaplan-Meier and Cox survival analyses with time of death as end-point. Mortality was calculated for all patients, and in 3 defined risk groups: high-risk patients (age ≥ 75 years and ASA > 2), intermediate-risk patients (age ≥ 75 years or ASA > 2), low-risk patients (age < 75 years and ASA ≤ 2). We also calculated mortality in patients with THA due to a hip fracture, and in patients with commonly used, contemporary, well-documented THAs. Adjustement was made for age, sex, ASA class, indication, and year of surgery.Results - Among the 79,557 included primary THA patients, 11,693 (15%) died after 5.8 (0-14) years' follow-up. Perioperative deaths were rare (30/105) and found in all fixation groups. Perioperative mortality after THA was 4/105 in low-risk patients, 34/105 in intermediate-risk patients, and 190/105 in high-risk patients. High-risk patients had 9 (CI 1.3-58) times adjusted risk of perioperative death compared with low-risk patients. All 4 modes of fixation had similar adjusted 3-day, 30-day, 90-day, 3-30 day, 30-90 day, 90-day-10-year, and 10-year mortality risk.Interpretation - Perioperative, short-term, and long-term mortality after primary THA were similar, regardless of fixation type. Perioperative deaths were rare and associated with age and comorbidity, and not type of fixation.

Postoperative 30-day complications after cemented/hybrid versus cementless total hip arthroplasty in osteoarthritis patients > 70 years.

Background and purpose - The use of cementless total hip arthroplasty (THA) in elderly patients is debated because of increased risk of early periprosthetic femoral fractures. However, cemented femoral components carry a risk of bone cement implantation syndrome. Hence, we compared in-hospital complications, complications leading to readmission and mortality ≤ 30 days postoperatively between hybrid/cemented (cemented femoral component) vs. cementless THA in osteoarthritis patients > 70 years.Patients and methods - This is a prospective observational cohort study in 9 centers from January 2010 to August 2017. We used 30-day follow-up from the Danish National Patient Registry, patient records, and data from the Danish Hip Arthroplasty Register. Only THAs performed as a result of osteoarthritis were included.Results - 3,368 (42%) of the THAs were cemented/hybrid and 4,728 (58%) cementless. The in-hospital complication risk was 7.7% after cemented/hybrid vs. 5.3% after cementless THA (< 0.001), statistically not significant when adjusting for comorbidities (p = 0.1). There were similar risks of complications causing readmission (5.7% vs. 6.2%) and mortality ≤ 30 days (0.2% vs. 0.3%). 15 cases (0.4%) of pulmonary embolism (PE) were found after cemented/hybrid vs. 4 (0.1%) after cementless THA (p = 0.001); none occurred within 24 hours postoperatively. 2 of the PEs after cementless THA led to mortality. Cemented/hybrid THA remained significantly associated with risk of PE (RR 3.9, p = 0.02), when adjusting for comorbidities. BMI > 35 was associated with highest risk of PE (RR 5.7, p = 0.003). The risk of periprosthetic femoral fracture was 0.2% after cemented/hybrid vs. 1.5% after cementless THA (p < 0.001) and the risk of dislocations was 1.2% after cemented/hybrid THA vs. 1.8% after cementless THA (p = 0.04).Interpretation - The higher risk of PE after cemented/hybrid THA and higher risk of periprosthetic femoral fractures and dislocations after cementless THA highlights that both medically and surgically complications are related to fixation technique and have to be considered.

Early stabilization of the uncemented Symax hip stem in a 2-year RSA study.

Background and purpose - The uncemented Symax hip stem has shown early proximal ingrowth as result of the BONIT-hydroxyapatite (HA) coating and the distal DOTIZE surface treatment. We evaluated 2-year postoperative radiostereometric analysis (RSA) migration of the Symax hip stem in THA patients. We also investigated the correlation between migration at 4 weeks and clinical outcomes after 2 years.Patients and methods - Patients in a 2-year clinical follow-up single-centre RSA randomized controlled trial were randomized to 2 different cup designs. All 45 patients received a Symax hip stem. RSA migration patterns of the Symax hip stem is presented here as a single cohort. RSA examinations were performed postoperatively, but before weight-bearing, and subsequently after 1, 3, 6, 12, and 24 months. Clinical outcomes and radiographic evaluations were assessed 3, 6, 12, and 24 months postoperatively.Results - During the first 4 weeks, the Symax hip stem subsided, rotated into retroversion, and translated posteriorly, after which the migration ceased and the prosthesis stabilized. All clinical outcomes improved from preoperatively to 2 years. There was no clinically or statistically significant correlation between subsidence and retroversion at 4 weeks and clinical outcomes after 2 years.Interpretation - RSA evaluation of the uncemented Symax hip stem confirms that the design principles and coating properties lead to early stabilization of the stem, as early as 4 weeks postoperatively. There was no correlation between subsidence and retroversion at 4 weeks and clinical outcomes after 2 years. Based on the predictive potential of the RSA technique, we anticipate excellent long-term survival of this hip stem.

A vitamin E blended highly cross-linked polyethylene acetabular cup results in less wear: 6-year results of a randomized controlled trial in 199 patients.

Background and purpose - Survivorship of total hip arthroplasty (THA) with the ultra-high molecular weight polyethylene (UHMWPE) monoblock cup has been limited due to periprosthetic osteolysis and aseptic loosening, secondary to wear of the UHMWPE. In response, a vitamin E blended highly cross-linked polyethylene (HXLPE) cup was developed. This study set out to compare the wear and clinical 6-year outcomes of vitamin E blended HXLPE with UHMWPE in an isoelastic monoblock cup in patients with hip osteoarthritis who underwent uncemented THA. The 2-year results have been reported previously. Patients and methods - For this randomized controlled trial 199 patients were included. 102 patients received the vitamin E blended HXLPE uncemented acetabular cup and 97 patients the uncemented UHMWPE monoblock cup. Clinical and radiographic parameters were obtained preoperatively, directly postoperatively, and at 3, 12, 24, and 72 months. Wear rates were compared using the femoral head penetration (FHP) rate. Results - 173 patients (87%) completed the 6-year follow-up. The mean NRS scores for rest pain, load pain, and patient satisfaction were 0.3 (SD 1), 0.6 (SD 1), and 8.6 (SD 1) respectively. The mean Harris Hip Score was 93 (SD 12). The FHP rate was lower in the vitamin E blended HXLPE cup (0.028 mm/year) compared with the UHMWPE cup (0.035 mm/year) (p = 0.002). No adverse reactions associated with the clinical application of vitamin E blended HXLPE were observed. 15 complications occurred, equally distributed between the two cups. The 6-year survival to revision rate was 98% for both cups. There was no aseptic loosening. Interpretation - This study shows the superior performance of the HXLPE blended with vitamin E acetabular cup with clinical and radiographic results similar to the UHMWPE acetabular cup.

Are Hooded, Crosslinked Polyethylene Liners Associated with a Reduced Risk of Revision After THA?

BACKGROUND: Hooded acetabular liners and head sizes ≥ 32 mm have both shown to have a beneficial effect on the revision rate for dislocation in THA. Experience with noncrosslinked polyethylene (nonXLPE) raised concerns regarding the risk of impingement damage, loosening, and osteolysis with hooded liners; however, the evidence for this in crosslinked polyethylene (XLPE) is inconclusive. The interaction between different femoral head sizes and hooded liners is not well understood, and it is unclear whether hooded XLPE liners have a beneficial effect on overall long-term survivorship. QUESTIONS/PURPOSES: We analyzed a large national joint registry to ask: (1) Is the use of hooded XLPE liners associated with a reduced revision rate for dislocation compared with nonhooded liners? (2) Is there a difference in the revision rate for aseptic loosening/osteolysis? (3) Is head size associated with any difference in the revision rate between hooded and nonhooded liners? METHODS: The Australian Orthopaedic Association National Joint Replacement Registry longitudinally maintains data on all primary and revision joint arthroplasties with nearly 100% capture. We analyzed all conventional primary THAs performed from registry inception in September 1999 until December 31, 2016 in patients with a diagnosis of osteoarthritis who had nonhooded or hooded XLPE bearings in a cementless acetabular shell. The study group included 192,659 THA procedures with XLPE liners, of which 67,904 were nonhooded and 124,755 were hooded. The mean age of patients receiving nonhooded liners was 70 years (range, 11-100 years); 44% were males. This was similar to the patients with hooded liners, who had a mean age of 70 years (range, 16-100 years); 45% were males. The main outcome measure was the cumulative percent revision at 15 years of the THA using Kaplan-Meier estimates of survivorship. We examined reasons for revision and and performed multivariable analysis to control for the confounding factors of three head size groups (< 32mm, 32mm, and > 32mm) and for the method of femoral fixation. RESULTS: There was a higher revision rate for dislocation for patients with nonhooded liners at all times to 15 years (HR, 1.31; 95% CI, 1.17-1.47; p < 0.001). There was a higher revision rate for the diagnosis of aseptic loosening/osteolysis with patients with nonhooded liners compared with hooded liners (HR, 1.19; 95% CI, 1.05-1.34; p = 0.006). Head sizes of 32 mm or larger were independently associated with a lower comparative revision rate between hooded and nonhooded liners, but this was not apparent for head sizes smaller than 32 mm. It appeared that the main driver of the finding in larger heads was a reduced dislocation risk with hooded liners for 32 mm heads (HR, 1.50; 95% CI, 1.23-1.80; p < 0.001) and for heads larger than 32 mm (HR, 1.50; 95% CI, 1.20-1.89; p < 0.001). CONCLUSIONS: Prior research has suggested that hooded acetabular liners may be associated with impingement, loosening, and osteolysis; however, in this large, registry-based report we found that XLPE hooded liners are not associated with an increased revision rate for aseptic loosening/osteolysis. Although there are many potential confounding variables in this registry analysis, if anything, surgeons using larger femoral heads and hooded liners likely did so in patients with a higher perceived dislocation risk. Patients with larger heads and XLPE hooded liners were, however, less likely to experience revision for dislocation. These liners therefore appear reasonable to use in primary THA at the surgeon's discretion. LEVEL OF EVIDENCE: Level III, therapeutic study.

The Outcome of Cemented Acetabular Components in Total Hip Arthroplasty for Osteoarthritis Defines a Proficiency Threshold: Results of 22,956 Cases From the Australian Orthopaedic Association National Joint Replacement Registry.

BACKGROUND: The declining popularity of cemented acetabular components is incongruous, given the published results of prostheses implanted using contemporary techniques. The outcome of arthroplasty has previously been demonstrated to correlate with surgeon experience and volume of practice. We aim to explore if surgeon volume alters outcomes of cemented acetabular components based on survivorship data from the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR). METHODS: An observational study was undertaken using a cohort of 22,956 patients with a primary diagnosis of osteoarthritis in the period 2003-2016 in whom cemented acetabular components were implanted. The cohort was stratified by age (greater than or less than 65 years) and annualized surgical volume of ≤10, >10-≤25, and >25 cases. RESULTS: Stratified by age and volume, there was a protective benefit against revision conveyed at volume thresholds of 10 cases per annum and 25 cases per annum for patients ≥65 years of age and <65 years of age, respectively. CONCLUSION: Cemented total hip arthroplasty has excellent survivorship out to 15 years based on AOANJRR data. This survivorship is further improved if surgeons perform a higher volume of cases, with >25 cases conferring the greatest benefit. The AOANJRR data set is used to define best practice; surgeons who choose to utilize cemented acetabular fixation should be encouraged to perform this technique in adequate volumes to minimize revision risk and ensure the preservation of this important surgical skill set.

Component Placement in Direct Lateral vs Minimally Invasive Anterior Approach in Total Hip Arthroplasty: Radiographic Outcomes From a Prospective Randomized Controlled Trial.

BACKGROUND: End-stage coxarthrosis is increasingly common; however, limited evidence exists on the effect of direct lateral approach (DLA) and minimally invasive direct anterior approach (MIDA) on component placement in total hip arthroplasty (THA). We therefore conducted a prospective, randomized controlled trial to determine the component placement in DLA vs MIDA in THA. METHODS: Between January 2012 and June 2013, 164 patients with clinically and radiologically confirmed coxarthrosis aged 20-80 years were randomized to either DLA or MIDA (active comparator). Excluded were patients with previous ipsilateral hip surgery, a body mass index >35 kg/m2, and/or mental disability. Primary clinical outcomes have been published elsewhere. Secondary outcomes included radiographic assessment of the acetabular component (cement-mantle thickness, inclination, and anteversion), femoral stem position (varus/valgus and THA index), offset restoration, and leg length discrepancy. RESULTS: The mean cement-mantle was significantly thicker in zone 1 in the MIDA group (mean difference = 0.51 mm, 95% confidence interval [CI] 0.09-0.93, P = .018), and the mean degrees of inclination and anteversion were higher in the MIDA group (mean difference = 2.5°, 95% CI 0.3-4.6, P = .023 and mean difference = 3.6°, 95% CI 2.2-5.0, P < .0001, respectively). According to the defined reference range, cup inclination was more often adequate in the DLA group (67.9% (53/78) in the DLA group vs 52.4% (43/82) in the MIDA group, P = .045). There were no differences in frontal or lateral femoral stem position, global offset restoration, or leg length discrepancy. CONCLUSION: In this population of Norwegian patients with coxarthrosis, radiographic assessment showed limited differences in component placement between MIDA and DLA. The findings suggest that component placement is similar in the 2 surgical approaches.

Bone ongrowth of a cementless silver oxide-containing hydroxyapatite-coated antibacterial acetabular socket.

BACKGROUND: The silver oxide-containing hydroxyapatite-coated socket (KYOCERA, Osaka, Japan) is a cementless antibacterial implant that has both the osteoconductivity of the HA and the antibacterial activity of silver. The silver oxide-containing hydroxyapatite coating was shown to have good osteoconductivity and new bone formation in vitro and in vivo. However, the histological bone ongrowth of this implant has not been proven in a clinical study. METHODS: We analyzed bone ongrowth using two silver oxide-containing hydroxyapatite-coated sockets that were removed in revision total hip arthroplasty for recurrent dislocation. A histomorphometric analysis was performed using a scanning electron microscope (SEM) connected to a CCD camera and an elemental analysis was performed by energy-dispersive elemental spectrometry (EDS). RESULT: A white structure thought to be osseous tissue was attached to the retrieved socket surface macroscopically, and histological bone ongrowth of the silver oxide-containing hydroxyapatite coating of the socket was confirmed by SEM. In addition, the presence of silver in the silver oxide-containing hydroxyapatite coating was confirmed in an elemental analysis by EDS. CONCLUSION: Histologically, the silver oxide-containing hydroxyapatite-coated socket presented bone ongrowth in this clinical study.

Fourteen-year experience with short cemented stems in total hip replacement.

PURPOSE: The age of the population requiring total hip replacement (THR) is increasing and this may lead to a return of cemented stems. Advantages of a short cemented femoral device include preservation of metaphyseal bone, easier insertion, and easier cement removal in case of revision. The purpose of this study is to describe the rationale and assess midterm results of unique innovative short cemented double-tapered polished stem applied with contemporary cementing techniques. METHODS: Our experience with this short cemented stem includes two different groups of elderly patients. Group 1 (prototype version of the short stem) from January 2005 to January 2008 counts 43 THR. Group 2 (final commercial version of the short stem) from January 2013 to January 2015 counts 54 THR. The average age in groups 1 and 2 was 79 and 75 respectively. Patients underwent clinical follow-up with the Harris Hip Score (HHS) and completed radiographic evaluation. RESULTS: Thirty-one patients of group 1 had died for reasons unrelated to their THR. The surviving 9 hips have a follow-up of 11.2 years. In group 2, eight  patients died for reasons unrelated to their THR. Follow-up for the surviving 40 patients is 4.6 years. HHS improved in both groups. In 34/43 hips of group 1 and in 41/54 of group 2 we observed a Barrack grade A cement mantle. Survival with revision of the stem for aseptic loosening as the endpoint was 100%. CONCLUSIONS: This study confirms the effectiveness of a short, polished, collarless, tapered cemented stem implanted with contemporary cementing techniques which appears as successful as the standard sized components.

Development of periprosthetic bone mass density around the cementless Metha® short hip stem during three year follow up-a prospective radiological and clinical study.

PURPOSE: The purpose of this study was to check the concept of the cementless Metha® short hip stem in order to find out whether proximal physiological load transfer can be achieved. METHODS: Fourty-three patients were included. Epidemiological factors were established. The Harris Hip Score was determined and measurement of bone mass density as well as osteodensitometric and radiological measurements was carried out pre-operatively, post-operatively, and after six, 12, 24, and 36 months. RESULTS: Harris Hip Score improved from 55.9 ± 12.4 pre-operatively to 94.8 ± 8.2 after 36 months (p < 0.001). After initial reduction of bone density in zones 1 and 7 up to six months post-operatively, there was a steady approximation of bone density to the initial values (p < 0.05). CONCLUSION: The Metha® short hip stem shows good clinical results. Furthermore, there is an increase of bone density in the proximal zones 1 and 7 between six and 36 months serving as a sign of physiological load transfer.

Early postoperative mortality similar between cemented and uncemented hip arthroplasty: a register study based on Finnish national data.

Background and purpose - Implant survival of cemented total hip arthroplasty (THA) in elderly patients is higher than that of uncemented THA. However, a higher mortality rate in patients undergoing cemented THA compared with uncemented or hybrid THA has been reported. We assessed whether cemented fixation increases peri- or early postoperative mortality compared with uncemented and hybrid THA. Patients and methods - Patients with osteoarthritis who received a primary THA in Finland between 1998 and 2013 were identified from the PERFECT database of the National Institute for Health and Welfare in Finland. Definitive data on fixation method and comorbidities were available for 62,221 THAs. Mortality adjusted for fixation method, sex, age group, and comorbidities among the cemented, uncemented, and hybrid THA was examined using logistic regression analysis. Reasons for cardiovascular death within 90 days since the index procedure were extracted from the national Causes of Death Statistics and assessed separately. Results - 1- to 2-day adjusted mortality after cemented THA was comparable to that of the uncemented THA group (OR 1.2; 95% CI 0.24-6.5). 3- to 10-day mortality in the cemented THA group was comparable to that in the uncemented THA group (OR 0.54; CI 0.26-1.1), and in the hybrid THA group (OR 0.64, CI 0.25-1.6). Pulmonary embolism or cardiovascular reasons as a cause of death were not over-represented in the cemented THA group. Interpretation - Early peri- and postoperative mortality in the cemented THA group was similar compared with that of the hybrid and uncemented groups.