The influence of hydroxyapatite coating on continuous migration of a Zweymuller-type hip stem: a double-blinded randomised RSA trial with 5-year follow-up.

BACKGROUND AND PURPOSE: Adding hydroxyapatite to a stem to enhance ingrowth is a matter of debate, even less is known about the long-term effect on stability by adding hydroxyapatite (HA). Continuous migration in the first 2-5 years is an indicator of failed osteointegration or pending failure, enhancing the risk of loosening within 10 years after initial surgery. We performed a double-blinded randomised RSA trial with 5-year follow-up, to compare and analyse migration characteristics of the hydroxyapatite uncoated (HA-) and hydroxyapatite coated (HA+) Zweymuller-type hip stem. PATIENTS AND METHODS: In this single-centre prospective randomised controlled trial 51 patients were randomised to receive either a HA- or a HA+ Zweymuller-type hip stem during total hip replacement. After 5 years, 35 patients were still eligible for follow-up evaluation. The migration pattern was measured by use of radio stereometric analysis (RSA) images up to 2 years to evaluate short-term migration, additionally RSA images were obtained 5 years postoperatively to assess late-term and continuous migration. Furthermore, the improvement of clinical outcome was analysed by HSS and HOOS ADL and pain subscales preoperative and after 5 years. RESULTS: After initial settling of the implant, no significant migration occurred up to 5 years post-surgery for HA+ as well as HA- prostheses. Continuous migration within the 2-5 years' time interval was not observed for both HA+ nor the HA- group in all directions (p < 0.05). No significant difference between both groups was observed (p < 0.10). In both groups the HHS and HOOS improved significantly at 5 years compared to baseline for both groups. Improvement was not altered by the hydroxyapatite coating. No significant difference between both groups was observed (p > 0.58). CONCLUSIONS: Addition of a hydroxyapatite coating did not influence the migration 5 years postoperatively for the Zweymuller-type hip stem.Clinical Trial Protocol number: NL 23524.048.08.

Ceramic-on-ceramic vs ceramic-on-polyethylene, a comparative study with 10-year follow-up.

BACKGROUND: In press-fit total hip arthroplasty (THA) ceramic-on-ceramic (CoC) bearings are a potential for overcoming the wear that is seen in ceramic-on-polyethylene (CoPE) bearings, and can lead to wear-induced osteolysis, resulting in loosening of the implant. However, CoC bearings show disadvantages as well, such as squeaking sounds and being more fragile, which can cause ceramic head or liner fracture. Because comparative long-term studies are limited, the objective of this study was to determine the long-term difference in wear, identify potential predictive factors for wear, investigate radiological findings such as osteolysis, and evaluate clinical functioning and complications between these bearings. AIM: To determine 10-year differences in wear, predictive factors for wear, and investigate radiological findings and clinical functioning between CoC and CoPE. METHODS: This observational prospective single-center cohort study with a 10-year follow-up includes a documented series of elective THAs. Primary outcome was wear measured by anteroposterior (AP) radiographs. Secondary outcomes were potential predictive factors for wear, complications during follow-up, Harris hip score (HHS), and radiological findings such as presence of radiolucency, osteolysis, atrophy, and hypertrophy around the cup. Due to the absence of wear in the CoC group, stratified analysis to identify risk factors for wear was only performed in the CoPE group by use of univariate linear regression analysis. HHS was expressed as a change from baseline and the association with bearing type was assessed by use of multivariate linear regression analysis, adjusted for potential confounders. RESULTS: A total of 17 CoPE (63.0%) and 25 CoC (73.5%) cases were available for follow-up and showed a linear wear of respectively 0.130 mm/year (range 0.010; 0.350) and 0.000 mm/year (range 0.000; 0.005), which was significant (P < 0.001) between both groups. Wear always occurred in the cranial direction. Cup inclination was the only predictive factor for polyethylene (PE) wear. No dislocations, ceramic head, or liner fractures were seen. The HHS showed a mean change from baseline of 37.1 points (SD 18.5) in the CoPE group and 43.9 (SD 17.0) in the CoC group. This crude difference of 6.8 (range -5.2; 18.7) in favor of the CoC group was not significant (P = 0.26) and was not significant when adjusted for age, gender, and diagnosis either (P = 0.99). No significant differences in complications and radiological findings were seen between groups. CONCLUSION: CoC bearing shows lower wear rates compared to CoPE at 10-year follow-up with cup inclination as a predictive factor for wear and no differences in complications, HHS, and radiological findings.

What is the role of cemented fixation in total knee arthroplasty? The two-year results of a randomized RSA controlled trial.

AIMS: For many designs of total knee arthroplasty (TKA) it remains unclear whether cemented or uncemented fixation provides optimal long-term survival. The main limitation in most studies is a retrospective or non-comparative study design. The same is true for comparative trials looking only at the survival rate as extensive sample sizes are needed to detect true differences in fixation and durability. Studies using radiostereometric analysis (RSA) techniques have shown to be highly predictive in detecting late occurring aseptic loosening at an early stage. To investigate the difference in predicted long-term survival between cemented, uncemented, and hybrid fixation of TKA, we performed a randomized controlled trial using RSA. METHODS: A total of 105 patients were randomized into three groups (cemented, uncemented, and hybrid fixation of the ACS Mobile Bearing (ACS MB) knee system, implantcast). RSA examinations were performed on the first day after surgery and at scheduled follow-up visits at three months, six months, one year, and two years postoperatively. Patient-reported outcome measures (PROMs) were obtained preoperatively and after two years follow-up. Patients and follow-up investigators were blinded for the result of randomization. RESULTS: RSA secondary stabilization did not show a significant difference between the three types of fixation. A maximum total point motion of less than 0.2 mm in the second postoperative year was shown in each group, which suggests stabilization of the implant. At 24 months after surgery, PROMs significantly improved compared to baseline in all treatment groups. No significant difference was observed between the three groups. CONCLUSION: Secondary stabilization measurements in this study demonstrated no significant difference between the groups. In all groups migration stabilized after initial settling of the implant. For this implant the long-term outcome is not expected to be influenced by the type of fixation to the bone. Cite this article: Bone Joint J 2021;103-B(1):98-104.

The migration pattern and initial stability of the Optimys short stem in total hip arthroplasty: a prospective 2-year follow-up study of 33 patients with RSA.

BACKGROUND AND PURPOSE: The consensus that bone stock preservation and optimal restoration of offset and leg length is important in total hip arthroplasty is now widespread, especially for young and active patients. Short stems seem promising in this aspect, though implant stability is still of concern. This study looked at the migration pattern of the Optimys short stem through RSA analysis. PATIENTS AND METHODS: 40 patients were included. RSA images were made directly postoperatively (within 5 days), at 6 weeks and at 3, 6, 12 and 24 months. Double examinations were made for precision measurement. HOOS and pain scores were obtained preoperatively and at 2 years. 4 patients were excluded due to protocol violation and 1 patient was excluded for RSA analysis with a CN number >110. 2 patients were lost to follow-up after 3 and 6 months (n = 1 lost, n = 1 deep infection, respectively). RESULTS: Mean age was 60 years with a mean BMI of 27. RSA analysis of 34 patients showed a significant initial median proximodistal translation (subsidence) of 0.21 mm (IQR 0.64-0.06) and anteversion-retroversion rotation of 0.59° (IQR 0.01-1.34) at 6 weeks, after which the stem stabilises and showed no further significant movement. Median migration in other directions was small. 4 patients had an initial subsidence of >2 mm, all showed secondary stabilisation. HOOS outcomes were satisfactory, with the domain symptoms and pain showing a median score of 95/100 at 2 years. CONCLUSIONS: After initial migration the Optimys achieves secondary stabilisation, suggesting low risk on long-term aseptic loosening. CLINICAL TRIALS REGISTRATION: NL47055.048.13.

Does hydroxyapatite coating enhance ingrowth and improve longevity of a Zweymuller type stem? A double-blinded randomised RSA trial.

INTRODUCTION: An ongoing discussion is whether using a hydroxyapatite coating enhances the ingrowth and longevity of a femoral stem in total hip arthroplasty. The best way to predict speed of ingrowth and long-term outcome is by evaluating micromotion by radiostereometric analysis. To study the effect of hydroxyapatite (HA) coating on the migration of the SL-PLUS hip stem, we performed a prospective double blind randomised controlled trial comparing the early migration of the hydroxyapatite (HA)-coated SL-PLUS stem compared to the Standard (non-coated) SL-PLUS stem. PATIENTS AND METHODS: 51 patients were randomly assigned to receive either an uncoated or a HA-coated femoral component during total hip replacement. RSA images were obtained direct postoperatively and at 6 weeks, 12 weeks, 6 months, 12 months and 24 months. HOOS scores were obtained preoperative and at final follow-up. RESULTS: RSA evaluation demonstrated significant migration up to 3 months postoperatively in both groups. After initial setting no significant migration was observed. There was no significant difference in migration between the HA-coated group and the uncoated group. Both Harris Hip Score (HHS) and HOOS domain scores (pain and ADL) significantly improved compared to baseline at 24 months after surgery in both treatment groups (p<0.001 for all comparisons). Improvement did not differ significantly between the 2 groups. CONCLUSIONS: At 2 years follow-up, the HA-coated and uncoated Zweymuller type, distal fitting stem do not show different migration patterns.

Early loosening of a press-fit cup with ceramic-on-ceramic articulation: our early results.

INTRODUCTION: In this study, we present the short-term results of the Selexys TH+ cup with the Ceramys inlay which is a press-fit cup with a ceramic-on-ceramic articulation. (Mathys, Bettlach, Switzerland). We compared the results with a retrospective-matched control group with a Delta PF cup (Lima, Udine, Italy), which is also a press-fit cup with a ceramic-on-ceramic articulation. MATERIALS AND METHODS: 257 elective hip arthroplasties with the Selexys TH+ cup in 250 patients placed in 2009 and 2010 were analyzed and compared with a control group retrospective analysis of the uncemented Delta PF cup (Lima, Udine, Italy) placed in 2007 and 2008 in 208 patients (222 hips). Surgical technique and surgeons were identical in both groups. RESULTS: During a follow-up period of 3-21 months, 19 aseptic loosenings (7.4 %) were found for the Selexys TH+ cup. The survival plotted by a Kaplan-Meier curve shows a 1-year survival of 87.4 %. The Lima Delta PF cup showed a 1-year survival of 99.5 %. Failure analysis showed no clear explanation for this early loosening. CONCLUSION: The Selexys TH+ cup combined with the Ceramys ceramic-on-ceramic inlay coupling show an unacceptable high early revision rate. Therefore, we advice against using this combination.

Obesity in total hip arthroplasty--does it really matter? A meta-analysis.

BACKGROUND AND PURPOSE: Discussion persists as to whether obesity negatively influences the outcome of hip arthroplasty. We performed a meta-analysis with the primary research question of whether obesity has a negative effect on short- and long-term outcome of total hip arthroplasty. METHODS: We searched the literature and included studies comparing the outcome of hip arthroplasty in different weight groups. The methodology of the studies included was scored according to the Cochrane guidelines. We extracted and pooled the data. For continuous data, we calculated a weighted mean difference and for dichotomous variables we calculated a weighted odds ratio (OR). Heterogeneity was calculated using I(2) statistics. RESULTS: 15 studies were eligible for data extraction. In obese patients, dislocation of the hip (OR = 0.54, 95% CI: 0.38-0.75) (10 studies, n = 8,634), aseptic loosening (OR = 0.64, CI: 0.43-0.96) (6 studies, n = 5,137), infection (OR = 0.3, CI: 0.19-0.49) (10 studies, n = 7,500), and venous thromboembolism (OR = 0.56, CI: 0.32-0.98) (7 studies, n = 3,716) occurred more often. Concerning septic loosening and intraoperative fractures, no statistically significant differences were found, possibly due to low power. Subjective outcome measurements did not allow pooling because of high heterogeneity (I(2) = 68%). INTERPRETATION: Obesity appears to have a negative influence on the outcome of total hip replacement.

Polyethylene wear particles do not induce inflammation or gelatinase (MMP-2 and MMP-9) activity in fibrous tissue interfaces of loosening total hip arthroplasties.

In vitro and in vivo studies have suggested that polyethylene wear particles are the main cause for osteolysis in prosthetic loosening. Elevated amounts of proteases including gelatinases (or matrix metalloproteinases MMP-2 and MMP-9) have been found in fibrous tissue interfaces of loosened total hip arthroplasties suggesting that proteolysis plays a role in osteolysis. The presence of proteases does not mean that they are active, because activity of proteases is highly regulated at the post-translational level. We investigated whether the activity of two major proteases that are active extracellularly and have been associated with loosening, MMP-2 and MMP-9, is involved in loosening of non-cemented hip implants with polyethylene acetabular components. Eight interface tissues retrieved during revision were studied with light and electron microscopy and by in situ zymography to localize MMP-2 and MMP-9 activity in combination with immunohistochemistry to localize MMP-2 and MMP-9 proteins. All interface tissues contained large amounts of polyethylene wear particles, either in large accumulations or dispersed in the extracellular matrix or intracellularly in fibroblasts. Particles were not encountered in association with MMP-2 or MMP-9 activity or leukocytes. Inflammation was never found. MMP-9 activity was restricted to macrophages and MMP-2 activity was restricted to microvascular endothelial cells mainly outside areas where particles were present. Our data indicate that wear particles do not induce activation of leukocytes or MMP-2 or MMP-9 activity. Therefore, aseptic loosening may not be particle induced but initiated by other mechanisms such as mechanical stress.

Primary hemiarthroplasty versus conservative treatment for comminuted fractures of the proximal humerus in the elderly (ProCon): a multicenter randomized controlled trial.

BACKGROUND: Fractures of the proximal humerus are associated with a profound temporary and sometimes permanent, impairment of function and quality of life. The treatment of comminuted fractures of the proximal humerus like selected three-or four-part fractures and split fractures of the humeral head is a demanding and unresolved problem, especially in the elderly. Locking plates appear to offer improved fixation; however, screw cut-out rates ranges due to fracture collapse are high. As this may lead to higher rates of revision surgery, it may be preferable to treat comminuted fractures in the elderly primarily with a prosthesis or non-operatively. Results from case series and a small-sample randomized controlled trial (RCT) suggest improved function and less pain after primary hemiarthroplasty (HA); however these studies had some limitations and a RCT is needed. The primary aim of this study is to compare the Constant scores (reflecting functional outcome and pain) at one year after primary HA versus non-operative treatment in elderly patients who sustained a comminuted proximal humeral fracture. Secondary aims include effects on functional outcome, pain, complications, quality of life, and cost-effectiveness. METHODS/DESIGN: A prospective, multi-center RCT will be conducted in nine centers in the Netherlands and Belgium. Eighty patients over 65 years of age, who have sustained a three-or four part, or split head proximal humeral fracture will be randomized between primary hemiarthroplasty and conservative treatment. The primary outcome is the Constant score, which indicates pain and function. Secondary outcomes include the Disability of the Arm and Shoulder (DASH) score, Visual Analogue Scale (VAS) for pain, radiographic healing, health-related quality of life (Short-form-36, EuroQol-5D) and healthcare consumption. Cost-effectiveness ratios will be determined for both trial arms. Outcome will be monitored at regular intervals over the subsequent 24 months (1, 3 and 6 weeks, and 3, 6, 12, 18, and 24 months). Data will be analyzed on an intention to treat basis, using univariate and multivariable analyses. DISCUSSION: This trial will provide level-1 evidence on the effectiveness of the two mostly applied treatment options for three-or four part and split head proximal humeral fractures in the elderly. These data may support the development of a clinical guideline for treatment of these traumatic injuries. TRIAL REGISTRATION: Netherlands Trial Register (NTR2040).

Small stem total hip arthroplasty in hypoplasia of the femur.

UNLABELLED: Total hip arthroplasty in hypoplastic femurs is technically difficult and the incidence of complications and aseptic loosening is relatively high. Cemented, uncemented, off-the-shelf, and custom-made stems all have been advocated in these cases. From 1978 to 1997, we performed 86 total hip arthroplasties in 77 patients with a hypoplastic femur using a cemented, off-the-shelf, small, curved, cobalt-chromium stem. We hypothesized results equaled those of the identical but larger-sized stems in normal-sized femora which were used as comparisons. Clinical and radiographic evaluations were performed. Minimum followup was 4.2 years (mean, 12 years; range, 4.2-20.3 years); mean Harris hip score was 88, and mean hip flexion was 104 degrees . Six stems were revised: four because of aseptic loosening, one after a femoral fracture, and one because of malpositioning. Complications included one perforation and one fracture of the femur, one fracture, one nonunion of the greater trochanter, and one deep infection. Implant survivorship for all hips at 15 years with aseptic revision of the stem as the end point was 90% (confidence interval, 82-99) which equaled results of the larger stems. The small off-the-shelf cemented Weber stem has a high long-term survival and a low complication rate. Survival compares favorably with other small-sized total hip systems. LEVEL OF EVIDENCE: Level III, therapeutic study, case-control.

Early complications after high tibial osteotomy: a comparison of two techniques.

This prospective cohort study compared opening wedge high tibial osteotomy with use of the Puddu plate and the Vitoss synthetic cancellous bone versus closing wedge high tibial osteotomy with use of the AO/ASIF L-plate, focusing on complications (nonunions, infections, loss of correction, reoperations) and patient satisfaction (visual linear analog scale). During a 10-month period, we performed high tibial osteotomy for 40 patients experiencing medial knee osteoarthritis and a varus deformity. The average follow-up was 11 months. The complication rate in patients treated with the opening wedge technique was significantly higher regarding tibial nonunion, loss of correction, and material failure. Patients in the closing wedge group were more satisfied with the postoperative result. This study found that the Puddu plate, despite 6 weeks of non-weight bearing facilitating the osseous consolidation with Vitoss cement, was not able to maintain the correction during the time required for bone healing.