Total Hip Arthroplasty Implants Research Articles

Cancer-Causing Effects of Orthopaedic Metal Implants in Total Hip Arthroplasty.

Metal implants have been preferentially used in THA due to its biocompatibility, mechanical stability and durability. Yet concerns have emerged regarding their potential to release metallic ions, leading to long-term adverse effects, including carcinogenicity. This study aimed to investigate the risk of cancer development in patients with orthopaedic metal implants in total hip arthroplasty (THA). Patients with THA conducted at a local tertiary implant centre from 2001-2008 were linked to the local cancer registry and followed up to the end of 2023. Standardized incidence ratios (SIRs) for cancer incidence and its confidence interval by Poisson distribution were calculated. Survival analysis was depicted using the Kaplan-Meier method, and the log-rank test was used to assess the differences across groups. The study cohort included 388 patients and 53 cancers diagnosed during follow-up, at least 5 years post THA. All-site cancer risks were increased in patients with THA (SIR: 1.97; 95% CI: 1.48-2.46), validated with chi-square analysis (chi-square = 15.2551, N = 100,388, p < 0.01). A statistically significant increase in multiple site-specific cancers including haematological cancers were identified. Patients with THA were found to have an increased risk for cancer compared to the general population during a mean follow-up of 16 years.

Extreme Serum Titanium Concentration Induced by Acetabular Cup Failure: Unveiling a Unique Scenario of Titanium Alloy Debris Accumulation.

The majority of contemporary total hip arthroplasty (THA) implants are constructed from Ti alloys, which are generally believed to generate fewer adverse local tissue reactions (ALTRs) compared to CoCr alloys. This study presents a case of unusual primary THA failure where a substantial release of Ti alloy debris was observed. A 52-year-old active male underwent THA after post-traumatic aseptic necrosis of the femoral head in 2006. Seventeen years after the procedure, the patient presented with groin pain and a restricted range of motion. X-rays revealed the protrusion of the alumina ceramic head through the Ti6Al4V acetabular cup. Trace element analysis indicated significantly elevated levels of serum Ti, Al, and V. CT and MRI confirmed Ti alloy cup failure and a severe ALTR. During revision surgery, it was found that the worn-out ceramic head was in direct contact with the acetabular cup, having protruded through a central hole it had created over time. No acetabular liner was found. Histological analysis of his tissue samples showed wear-induced synovitis with areas of multinucleated foreign body giant cells and the accumulation of numerous metal particles but no acute inflammatory response. Six months after the revision THA, the patient has experienced favourable outcomes. This case provides an instructive illustration for studying the consequences of the substantial release of Ti alloy debris from orthopedic implants.

Survival analysis of 3D printed acetabular implants in revision total hip arthroplasty associated with severe pelvic discontinuities.

Surgeons still face difficulties when performing aseptic acetabular revision on patients with extensive defects. Advances in three-dimensional printing technology (3DP) have afforded to the surgeons to create a patient-specific implant matching the morphology and topography of the defect. The aim of the current research was to determine the survivorship in the treatment of acetabular bone defects with pelvic discontinuity (PD). In order to reconstruct Paprosky type III defects with PD, twenty-three patients underwent revision total hip arthroplasty (THA) utilizing 3D-printed implants (Mobelife). The primary outcomes were the implant-associated failure rate correlated with survivorship. As secondary variables, complications and the effect of age, sex, comorbidities, history of infections and the presence of other lower limb arthroplasties on a new revision were analyzed. Patients were followed out to a mean of 67.22 ± 39.44 months (range, 0.9-127 months). Mobelife implant mean survival was 102.57 ± 9.90 months (95% CI 83.17-121.96). The cohort's implant one-year survival rate was 87%; at ten years, it dropped to 78.3%. There were four revisions: three due to periprosthetic joint infection (PJI) and one case due to aseptic loosening. Cox regression analysis did not identify any variable as predictor of failure. The use of 3DP patient-specific acetabular components has shown encouraging results and it is a viable treatment option for addressing acetabular defects with combined PD in aseptic THA revision.

Long-term results of total hip arthroplasty in severe congenital hip disease: A ten- to 20-year follow-up study

IntroductionThe impact of bone deformities, previous surgeries, and the surgical technique in total hip arthroplasty (THA) for congenital dislocation of the hip (CDH) at a long-term has not been clearly defined yet. In this single-centre observational study we sought to assess patients undergoing THA due to osteoarthritis secondary to severe CDH with low or high dislocation ten- to 20-years after surgery. To determine this purpose, we assessed: (1) THA-related complications and reoperations; (2) the clinical outcome, patients’ satisfaction and radiological results; and (3) the possible risk factors for reoperation with particular attention to the surgical technique and the influence of prior surgeries. HypothesisWe hypothesized that an anatomical reconstruction of the hip would decrease the reoperations rates in patients undergoing THA with severe CDH. MethodsSeventy-five patients (85 hips) operated between 1999 and 2012 at our large tertiary hospital were analyzed. Fifty-six hips were diagnosed as low dislocation (group 1) and 29 hips as high dislocation (group 2). The existence of prior surgeries was frequent: group 1, pelvic osteotomies 6 hips, femoral osteotomies 7, tectoplasty (shelf) 6, resection arthroplasty 1 and lowering of the greater trochanter 1; group 2 included pelvic osteotomies 10 hips, femoral osteotomies 10, and a femoral lengthening 2. The number of additional procedures during THA was: group 1 (19/56 [34%]), acetabular roof bone autograft 8 hips, acetabular medial wall autograft 2, hardware removal 6, extended femoral osteotomy 2, and a femoral shortening 1; group 2 (20/29 [69%]), acetabular bone autograft 12 hips, medial autograft 1, hardware removal 1, extended femoral osteotomy 2, and a femoral shortening 4 hips. The clinical and the radiological analysis were compared in both groups for a minimum follow-up of ten years. Cox regression models were used to detect risk factors for reoperation. ResultsNine patients (13.8%) required reoperation for the following reasons: cup loosening (5 hips), periprosthetic femoral fracture (3) and stem loosening (1); seven had prior surgeries. The 12-year survival rate for reoperation for any reason was 96.3% (95% confidence interval [CI] 91.2–100) in group 1 and 75.7% (95% CI, 65.8–90.8) in group 2 (p=0.003). Patients with high dislocation (p=0.02, hazard ratio [HR]: 6.25, 95% CI, 1.26–30.9) and those with an acetabular component inclination placed out of the target zone between 35° and 50° (p=0.03, HR: 4.27, 95% CI, 1.13–16.1) had a higher risk of reoperation. DiscussionAn optimal placement of the acetabular component decreased the reoperation rates in patients undergoing THA for severe CDH. Hips with high dislocation and the existence of prior surgery can affect THA implantation. Level of evidenceIII; retrospective; comparative.

Two-Year Outcomes of Novel Dual-Mobility Implant in Primary Total Hip Arthroplasty.

Dual-mobility (DM) implants for total hip arthroplasty (THA) have gained popularity due to their potential to reduce hip instability and dislocation events that may lead to revision surgery. These implants consist of a femoral head articulated within a polyethylene liner, which articulates within an outer acetabular shell, creating a dual-bearing surface. Our study aimed to report our observations on the survivorship of a novel DM implant for primary total hip arthroplasty at two years. We conducted a retrospective, multicenter study to assess the clinical outcomes of patients undergoing a THA with a novel DM implant (OR3O acetabular system™, Smith & Nephew, Inc., Memphis, TN) from January 2020 to September 2021. Patient demographics, surgical information, and survivorship data were collected from medical records for patients with a minimum of two years of follow-up. Primary outcomes included overall implant survivorship at two years as well as aseptic survivorship, revision rates of the DM acetabular shell, and average time to revision. Patient-reported outcomes were collected in the form of HOOS JR. A total of 250 hips in 245 patients had a minimum two-year follow-up. Primary osteoarthritis (80%) was the most common indication for index THA. The average aseptic survivorship of the DM acetabular components at two years for the cohort was 98.4% and survivorship of the acetabular implants overall was 97.6%. There were a total of four (1.6%) aseptic revisions of the DM acetabular component. Reasons for aseptic acetabular revision included one case of instability, one intraprosthetic dislocation, one periprosthetic acetabular fracture, and one malpositioned acetabular cup resulting in impingement. The mean time of follow-up was 893.9 days. Eighty-seven patients had preoperative and two-year HOOS JR available. HOOS JR improved by an average of 38.5 points. This novel DM acetabular implant demonstrates excellent survivorship at two years follow-up with low rates of instability and intraprosthetic dislocation and no episodes of metal-on-metal corrosion. Use of the DM implant demonstrated clinically relevant improvements in patient-reported outcomes at two years.

Variations in pelvic tilt during day-to-day activities after total hip arthroplasty measured with an ultrasound system

IntroductionThe pelvis plays a major role in the orientation of total hip arthroplasty (THA) implants and consequently, on the postoperative stability of the new hip joint. The relationship between the spine and pelvis affects the functional orientation of the acetabular cup, although this relationship differs between individuals and the positions encountered in everyday life. We believe this should be factored in when planning the THA procedure. This led us to conduct an in vivo ultrasound study to document the values of pelvic tilt in standing, sitting and lying positions in patients who have advanced hip osteoarthritis, before and after they undergo THA. HypothesisThe pelvic tilt when standing, sitting and lying supine does not change significantly after THA. Materials and methodsThe pelvic tilt, defined as the angle between the anterior pelvic plane and a vertical line was measured using an ultrasound device in 30 patients before the THA procedure and again 6 months later in standing, sitting and lying positions. The measurements were done during an office visit with the patient on an examination table for the lying position, on a chair for the sitting position and with the heels and occiput against the wall for the standing position. ResultsThe preoperative and 6-month postoperative pelvic tilt were –5.6̊±10.4̊ [–30.6̊; 11.7̊] and –5.8̊±7.9̊ [–20.6̊; 10.4̊] (p=0.4129) when standing, –44.5̊±6.10 [–53.8̊; –23.9̊] and –43.5̊±6.9̊ [–54.4̊; –17.3̊] (p=0.5760) when sitting, –88.3̊±5.1̊ [–99.3̊; –78.7̊] and –87.9̊±5.9̊ [–97.6̊; –72.4̊] (p=0.6106) when lying supine, respectively. There was no significant difference in the pelvic tilt before and 6 months after THA procedure. Variations of±5̊; ±5–10̊; ±10–15̊ and 15–20̊ were found in 72% (18); 20% (5); 4% (1) and 4% (1) of patients when lying supine, 56% (14); 36% (9); 8% (2); 0% (0) of patients when standing and 76% (19); 24% (6); 0% (0); 0% (0) when sitting. The mean variation for each patient between the preoperative and 6 months postoperative measurement was 4.8±3.4̊ [0.8̊; 10.4̊] (p=0.4129), 3.5±2.3̊ [0.2̊; 9.1̊] (p=0.5760), and 4.6̊±3.2̊ [1.2̊; 15.4̊] (p=0.6106) for the standing, sitting and lying positions respectively. ConclusionThe pelvic tilt does not significantly change 6 months after THA. Taking into account the various positions used in everyday life may help to optimize the implant position. We have described the use of an affordable, accurate and non-irradiating device that provides fast and easy measurements of pelvic tilt in various positions. Level of evidenceIV.

Total Hip Arthroplasty for Low-Grade Developmental Hip Dysplasia Changes the Ipsilateral Knee Alignment on the Axial and Coronal Planes

Background: There is a paucity of data regarding the post-operative influence of total hip arthroplasty (THA) on the axial and coronal alignments of the ipsilateral knee. A CT study was designed to assess the post-THA changes in axial and coronal knee alignments in low-grade dysplastic hips. Methods: Forty Crowe I–II dysplastic hips in 37 patients were assessed: a pre-operative CT scan from the fourth lumbar vertebra to the tibial plateaus was compared to a similar post-operative CT scan performed after a minimum of 2 years after THA. Results: THA implantation caused significant post-operative changes in terms of the rotation height (2 mm lowering; p = 0.003); center of rotation medialization (10 mm medialization; p &lt; 0.001); femoral offset (11 mm increase; p &lt; 0.001); femoral antetorsion (22° internal rotation; p &lt; 0.001), and hip internal rotation (9° internal rotation; p &lt; 0.001). The femoral axis angle deviated in the valgus (5.5° ± 1.1°, p &lt; 0.001) and the mechanical lateral distal femoral angle deviated in the varus (86° ± 2.7°, p = 0.001). The pelvic–tibial alignment changed from 88.2° ± 11.7° to 96° ± 9.3° (p &lt; 0.001). Patellar alignment was not influenced. Conclusions: In conclusion, THA imposes significant changes in low-grade dysplastic hips: all the modifications tend to neutralize the coronal alignment and, mostly, the rotational alignment, without substantial and durable variations of the patellofemoral joint. Large clinical trials should confirm whether radiological changes impact anterior knee pain and patellar stability.

Dynamic hip screw in proximal femoral fractures followed by “single-stage” hip arthroplasty—retrospective analysis

The aim of this study is to present the results of single-stage total hip arthroplasty (THA) after Dynamic Hip Screw (DHS) failure, or secondary posttraumatic osteoarthrosis. From 2003 to 2020, 15 THAs were performed in group of 15 patients for the treatment of DHS failure, or for late complications following femoral neck and pertrochanteric fractures. The mean follow-up period after arthroplasty was 46.9 months (range 7–139). The patients were evaluated retrospectively—both clinically and radiographically, focussing on the demography, infection rate and other complications (revision surgery), during the year 2023. 9 males and 6 females were included in the study, with a mean age of 56.5 years (range 29–93) at the time of primary osteosynthesis. Each of them had proximal femoral fracture treated primarily with a DHS and then late one-stage revision surgery, with hardware removal and THA implantation. The median time between DHS osteosynthesis and THA was 41.2 months (range 4–114). Four patients (26.6%) had complications after THA, with the need for revision in two cases (13.3%). Dislocation rate was 6.6% (one case), with the need for repeated-revision of THA. The infection rate was 6.6% (one patient) with the need for revision of THA. Peroperative periprosthetic femoral fracture was observed in 13.3% (two patients) without any other problems. Six patients (40%) died during the follow-up period. Single-stage total hip arthroplasty with concomitant hardware removal bears a high- mortality rate, with a higher incidence of postoperative complications compared to elective THA.

Do the sizes of total hip arthroplasty implants match between 3D planning software and 2D templating?

IntroductionThe use of three-dimensional (3D) planning before a total hip arthroplasty (THA) procedure is becoming increasingly popular as it offers several theoretical benefits: better restoration of a patient's anatomy, fewer intraoperative problems, and lower THA cost. It is said to be more accurate than two-dimensional (2D) planning, but as far as we know, no study has investigated how well the implant sizes match between 3D and 2D planning for a surgeon who is just starting to use 3D planning. Consistent implant sizes would make it easier for a surgeon to transition from one system to another. This led us to conduct a retrospective comparative study to: (1) compare how well the implant sizes match between a 3D planning system and a 2D planning method (conventional radiography using templates); (2) determine if the sizes planned on the 3D system match the implants that were used in the patient; (3) determine if the sizes planned with the 2D method match the implants that were used in the patient. HypothesisThere is a good match in the implant sizes between the 3D and 2D planning. MethodsA retrospective observational, single-surgeon study was done with patients who underwent THA between January 2019 and September 2021 at a single teaching hospital. For each patient, the size of the THA implants was planned preoperatively in 3D using proprietary software (Optimized Positioning System™, Corin) and 2D templating. These patients were the first to be operated on by this surgeon based on 3D planning. ResultsForty-nine patients were included. The implant size matched exactly between the two planning methods for 20% (10/49) of cups [one size larger with 3D in 35% of hips (17/49) and two sizes larger in 20% of hips (10/49)], for 53% (26/49) of femoral stems [one size smaller with 3D in 53% of hips (26/49)] and for 14% (7/49) of complete THA implant systems (cup, femoral stem, femoral head). The size planned in 3D was the same as the cup size implanted in 51% (25/49) of hips, as the femoral stem size in 65% (32/49) and as the complete THA system in 22% (11/49). The cup was within one size in 88% (43/49) of hips and the femoral stem was within one size in 98% (48/49) of hips. The size planned in 2D was the same as the cup size implanted in 45% (22/49) of hips, as the femoral stem size in 63% (32/49) and as the complete THA system in 18% (9/49). The cup was within one size in 86% (42/49) of hips and the femoral stem was within one size in 96% (47/49) of hips with 2D templating. There was no statistically significant difference in the size matching between the 2D and 3D techniques for either the implanted cup (p=0.5) or the implanted femoral stem (p=0.8). ConclusionThere is a poor match between the implant sizes determined by 3D and 2D planning. Based on our findings, the shift from 2D templating to 3D planning must be done gradually given the learning curve associated with 3D systems. Level of evidenceIII; comparative retrospective study.

Demographic characteristics influencing the stem subsidence in total hip arthroplasty: an imaging study

IntroductionThe present study evaluated whether patient demographic characteristics influence the subsidence of the stem in total hip arthroplasty (THA). The following characteristics were evaluated: age, height, weight, and sex. The association between the time elapsed from the THA implantation and the amount of stem subsidence was also investigated.MethodsThe records of patients who underwent THA in the period between 2016 and 2023 were accessed. All patients underwent two-staged bilateral THA using cementless DePuy collarless Corail (DePuy Synthes, Raynham, MA, USA) stems. The following parameters were measured and compared to assess stem subsidence: distance from the proximal femur at the stem bone interface and the medial apex of the regular triangle built within the trochanter minor (point A); distance from the medial apex of the regular triangle built within the trochanter minor and the distal portion of the femoral stem (point B).ResultsOverall, 294 patients were included. 62% (182 of 294 patients) were women. 45% (134 of 296 THAs) were on the right side. The mean age was 64.9 ± 10.4 years. The mean BMI was 28.3 ± 5.1 kg/m2. The mean length of the follow-up was 14.4 ± 11.0 months. The mean subsidence in point A was 2.1 mm (P < 0.0001), and that in point B was 3.1 mm (P < 0.0001). There was evidence of a weak positive association between patient weight (P < 0.0001), age (P = 0.03), follow-up (P = 0.002) and the amount of stem subsidence. Patient height did not demonstrate any association with the amount of stem subsidence (P = 0.07). There was no difference in stem subsidence between women and men (P = 0.9).ConclusionStem subsidence in THA using cementless DePuy collarless Corail implants is approximately 2.6 mm after 14.4 months. Greater patient weight, age, and longer time elapsed from THA implantation were associated with greater stem subsidence. Patient height and sex did not demonstrate any influence on the amount of stem subsidence. These results must be considered in light of the limitations of the present study.

Comparison between standard and dual mobility implants in total hip arthroplasty for femoral neck fractures in elderly

Background: Dislocation is a major concern after total hip replacement (THR) in displaced fracture neck of femur. Recent studies have shown reduced dislocation rates with dual mobility THR (DMTHR) for femur neck fractures; however, there is a lack of comparative research to show its superiority over conventional THR. Further, its role in the Asian subcontinent, where the patient requires sitting cross-legged or squatting, has not been studied. Methods: A prospective cohort study of 30 elderly patients with displaced NOF with a minimum follow-up of 2-year. Sixteen patients were operated on with DMTHR and fourteen patients with conventional THR. Both the groups were matched; radiological and functional outcomes in terms of Harris hip score (HHS), visual analog scale (VAS), range of motion, and dislocation rate were compared between the two groups. Results: Mean HHS of the DMTHR group was 79.99 at three months and 92.73 at the end of the 2 year postoperatively, which was significantly better than the conventional THR group 59.5 at three months and 88.14 at 2-year. The range of motion was significantly better in the DMTHR group than the conventional THR group. There was no significant difference in radiological outcomes and postoperative dislocation rate between the two groups. Conclusions: Dual mobility implants give better results than conventional implants for primary THA in elderly patients of displaced FNOF regarding better function and greater range of motion. More long-term multicentric studies are still needed.

THA-Net: A Deep Learning Solution for Next-Generation Templating and Patient-specific Surgical Execution

BackgroundThis study introduces THA-Net, a deep learning inpainting algorithm for simulating postoperative total hip arthroplasty (THA) radiographs from a single preoperative pelvis radiograph input, while being able to generate predictions either unconditionally (algorithm chooses implants) or conditionally (surgeon chooses implants). MethodsThe THA-Net is a deep learning algorithm which receives an input preoperative radiograph and subsequently replaces the target hip joint with THA implants to generate a synthetic yet realistic postoperative radiograph. We trained THA-Net on 356,305 pairs of radiographs from 14,357 patients from a single institution’s total joint registry and evaluated the validity (quality of surgical execution) and realism (ability to differentiate real and synthetic radiographs) of its outputs against both human-based and software-based criteria. ResultsThe surgical validity of synthetic postoperative radiographs was significantly higher than their real counterparts (mean difference: 0.8 to 1.1 points on 10-point Likert scale, P < .001), but they were not able to be differentiated in terms of realism in blinded expert review. Synthetic images showed excellent validity and realism when analyzed with already validated deep learning models. ConclusionWe developed a THA next-generation templating tool that can generate synthetic radiographs graded higher on ultimate surgical execution than real radiographs from training data. Further refinement of this tool may potentiate patient-specific surgical planning and enable technologies such as robotics, navigation, and augmented reality (an online demo of THA-Net is available at: https://demo.osail.ai/tha_net).

EVALUATION OF PROXIMAL FEMORAL BONE MINERAL DENSITY IN CEMENTLESS TOTAL HIP ARTHROPLASTY: A THREE-ARM PROSPECTIVE RANDOMIZED CONTROLLED TRIAL

Femoral stem design affects periprosthetic bone mineral density (BMD), which may impact long term survival of cementless implants in total hip arthroplasty (THA). The aim of this study was to examine proximal femoral BMD in three morphologically different uncemented femoral stems designs to investigate whether one particular design resulted in improved preservation of BMD.119 patients were randomized to receive either a proximally coated dual taper wedge stem, a proximally coated anatomic stem or a fully coated collarless triple tapered stem. Dual energy x-ray absorptiometry scans (Lunar iDXA, GE Healthcare, Madison, WI) assessed BMD across the seven Gruen zones pre-operatively, and post-operatively at 6-weeks, 1-year, and 2-years comparing the unoperated contralateral femur as a control.BMD increased in zones one (2.5%), two (17.1%), three (13.0%), five (10%) and six (17.9%) for all stems. Greater preservation of BMD was measured on the lateral cortex (zone 2) for both the dual taper wedge and anatomic stems (p = 0.019). The dual taper wedge stem also demonstrated preservation of BMD in the medial calcar (zone 7) whilst the anatomic and triple taper stem declined in this region, however this was not statistically significant (p = 0.059). BMD decreased on average by 2.1% in the mid-diaphysis region, distal to the stem tip (zone 4) for all implants. All stems performed equivalently at final follow-up in all patient reported outcome measures.Implant design was shown to impact BMD changes. All stems preserved bone at the metaphyseal level in early follow-up, which theoretically indicates favorable implant fixation. There was no significant stress shielding observed, however longer follow-up is required to elucidate the impact of this finding on implant survivorship.

THIRTY YEARS’ FOLLOW-UP OF THREE COMMONLY USED FEMORAL STEMS IN THE NORWEGIAN ARTHROPLASTY REGISTER: 1987–2021

The Norwegian Arthroplasty Register (NAR) started collecting data on total hip arthroplasty (THA) in 1987. Very long-term results of implants for THA are scarce. We aimed to show long-term results for the three most used femoral stems, operated from 1987.We included the uncemented Corail femoral stem (n=66,309) and the cemented Exeter stem (n=35,050) both of which are currently in frequent use. In addition, we included the Charnley stem (n=32,578, in use until 2014). To ensure comparable conditions, stems fixated with low viscosity cement and stems revised due to infections were excluded. Differences in risk of revision (all reasons and stem revisions) were assessed with Kaplan-Meier and Cox regression analyses with adjustment for possible confounding from age, sex and diagnosis (OA, other). Stem revision was defined as a revision caused by loosening of the stem, dislocation, osteolysis in the femur, or periprosthetic femur fracture, and in which the femoral component was removed or exchanged.The median and max follow-up for Corail, Exeter and Charnley were 6.3 (33.1), 8.0 (34.2) and 13.1 (34.3) respectively. Thirty years survival estimates for Corail, Exeter and Charnley stems were 88.6% (CI:85.8–90.9%), 86.7% (83.7–89.2%) and 87.1% (85.4–88.5%) respectively with stem revision as endpoint, and 56.1% (CI:53.1–59.1%), 73.3% (70.5–76.1%) and 80.2% (78.4–82.0%) with all THA revisions as endpoint. Compared to the Corail, the Exeter (HRR=1.3, CI:1.2–1.4) and the Charnley (HRR=1.9, CI:1.7–2.1) had a significant higher risk of stem revision. Women 75 years and older had better results with the cemented stems. Analyses accounting for competing risk from other causes of revision did not alter the findings.The uncemented Corail stem performed well in terms of stem revisions for stem-related revision causes compared to two frequently used cemented stems with very long follow-up. The differences between the three stems were small.

Comparison of the Mechanical and Osseointegrative Performance of Porous Tantalum and Titanium for Acetabular Implantation in Total Hip Arthroplasty: A Literature Review

Introduction: Stability of the acetabular component is a critical factor in the success of primary and revision total hip arthroplasty (THA) procedures. As such, the identification of implant surface characteristics that maximize stability of the acetabular cup is an important research objective. While titanium has historically been the most commonly used implant material, the proportion of THA procedures utilizing porous tantalum (PTa) implants has increased in recent years. The objective of this review is to examine the comparative mechanical and osseointegrative performance of PTa and porous titanium (PTi) and interpret these results in the context of primary and secondary stability of acetabular implants in THA, as characterized by strength of initial mechanical attachment and successful interlocking at the bone-implant interface, respectively. Methods: A literature search using a predetermined protocol and inclusion criteria yielded 7 articles presenting results of comparative testing of mechanical performance or osseointegration of PTa and PTi in the context of THA. Results: Neither PTa nor PTi presented consistently superior results in mechanical tests designed to correlate to primary stability at the metallo-biological surface nor in measures of osseointegration intended to represent secondary stability in THA. Discussion: In comparing PTa and PTi, it appears that the characteristics of the implant coating's pores may have a more significant impact on factors affecting the stability of an acetabular cup implant than the metal selected. However, determining the ideal pore morphology for this application is complex; pore characteristics that would suggest mechanical compatibility may conflict with those that would encourage more effective osseointegration. Conclusion: When extrapolated to be indicators of hypothetical clinical success, the results of this review are consistent with those of recently released macro-analyses of clinical outcomes: PTa and PTi acetabular cups, as they are currently manufactured, produce clinically equivalent outcomes. In the development and comparison of coating options, pore morphology and its complex effects on stability must be adequately accounted for; only then can we reach a faithful conclusion regarding the ideal porous adhesion surface for acetabular implant in THA.

Is the Direct Anterior Approach for Total Hip Arthroplasty Effective in Obese Patients? Early Clinical and Radiographic Results from a Retrospective Comparative Study.

Background and objectives: Total hip arthroplasty (THA) in obese patients (BMI > 30) is considered technically demanding, and it is associated with higher rates of general and specific complications including infections, component malpositioning, dislocation, and periprosthetic fractures. Classically, the Direct Anterior Approach (DAA) has been considered less suitable for performing THA surgery in the obese patient, but recent evidence produced by high-volume DAA THA surgeons suggests that DAA is suitable and effective in obese patients. At the authors' institution, DAA is currently the preferred approach for primary and revision THA surgery, accounting for over 90% of hip surgeries without specific patient selection. Therefore, the aim of the current study is to evaluate any difference in early clinical outcomes, perioperative complications, and implant positioning after primary THAs performed via DAA in patients who were divided according to BMI. Material and methods: This study is a retrospective review of 293 THA implants in 277 patients that were performed via DAA from 1 January 2016 to 20 May 2020. Patients were further divided according to BMI: 96 patients were normal weight (NW), 115 were overweight (OW), and 82 were obese (OB). All the procedures were performed by three expert surgeons. The mean follow-up was 6 months. Patients' data, American Society of Anesthesiologists (ASA) score, surgical time, days in rehab unit, pain at the second post-operative day recorded by using a Numerical Rating Scale (NRS), and number of blood transfusions were recorded from clinical charts and compared. Radiological evaluation of cup inclination and stem alignment was conducted on post-operative radiographs; intra- and post-operative complications at latest follow-up were recorded. Results: The average age at surgery of OB patients was significantly lower compared to NW and OW patients. The ASA score was significantly higher in OB patients compared to NW patients. Surgical time was slightly but significantly higher in OB patients (85 ± 21 min) compared to NW (79 ± 20 min, p = 0.05) and OW patients (79 ± 20 min, p = 0.029). Rehab unit discharge occurred significantly later for OB patients, averaging 8 ± 2 days compared to NW patients (7 ± 2 days, p = 0.012) and OW patients (7 ± 2 days; p = 0.032). No differences in the rate of early infections, number of blood transfusions, NRS pain at the second post-operative day, and day of post-operative stair climbing were found among the three groups. Acetabular cup inclination and stem alignment were similar among the three groups. The perioperative complication rate was 2.3%; that is, perioperative complication occurred in 7 out of 293 patients, with a significantly higher incidence of surgical revisions required in obese patients compared to the others. In fact, OB patients showed a higher revision rate (4.87%) compared to other groups, with 1.04% for NW and 0% for OW (p = 0.028, Chi-square test). Causes for revision in obese patients were aseptic loosening (2), dislocation (1), and clinically significant post-operative leg length discrepancy (1), with a revision rate of 4/82 (4.87%) during follow-up. Conclusions: THA performed via DAA in obese patients could be a solid choice of treatment, given the relatively low rate of complications and the satisfying clinical outcomes. However, surgical expertise on DAA and adequate instrumentation for this approach are required to optimise the outcomes.

Selective Use of Dual-Mobility Did Not Significantly Reduce 90-Day Readmissions or Reoperations After Total Hip Arthroplasty

BackgroundSelective use of dual mobility (DM) implants in total hip arthroplasty (THA) patients at high dislocation risk has been proposed. However, evidence-based utilization thresholds have not been defined. We explored whether surgeon-specific rates of DM utilization correlate with rates of readmission and reoperation for dislocation. MethodsWe retrospectively reviewed 14,818 primary THA procedures performed at a single institution between 2011 and 2021, including 14,310 fixed-bearing (FB) and 508 DM implant constructs. Outcomes including 90-day readmissions and reoperations were compared between patients who had FB and DM implants. Cases were then stratified into 3 groups based on the attending surgeon’s rate of DM utilization (≤ 1, 1 to 10, or > 10%) and outcomes were compared. ResultsThere were no differences in 90-day outcomes between FB and DM implant groups. Surgeon frequency of DM utilization ranged from 0% to 43%. There were 48 surgeons (73%) who used DM in ≤ 1% of cases, 11 (17%) in 1% to 10% of cases, and 7 (10%) in > 10% of cases. The 90-day rates of readmission (7.3% versus 7.6% versus 7.2%, P = .7) and reoperation (3.4% versus 3.9% versus 3.8%, P = .3), as well as readmission for instability (0.5% versus 0.6% versus 0.8%, P = .2) and reoperation for instability (0.5% versus 0.5% versus 0.8%, P = .6), did not statistically differ between cohorts. ConclusionSelective DM utilization did not reduce 90-day readmissions or reoperations following primary THA. Other dislocation-mitigation strategies (ie, surgical approach, computer navigation, robotic assistance, and large diameter FBs) may have masked any benefits of selective DM use.

Real-world 2-year clinical and economic outcomes among patients receiving a medial collared, triple tapered primary hip system versus other implants for total hip arthroplasty

Objective To evaluate real-world outcomes of patients receiving ACTIS, a medial collared, triple-tapered (MCTT) hip system vs. other implants, for primary total hip arthroplasty (THA). Methods Patients with THA between 2016–2021 from Mercy Healthcare Systems–Orthopedics Database were evaluated. The primary outcome was the 2-year revision. Secondary outcomes included operating room (OR) time, length of stay (LOS), and discharge disposition. Fine Stratification and Weighting (FSW) controlled for baseline characteristic differences between ACTIS and other implant groups. Cox proportional regression evaluated the hazard ratio (HR) for revision. Results Among 9,225 patients with 10,205 THAs (mean [SD] age 66.8 [11.3] years, 56.0% female), MCTT was implanted in 1,591 hips and other implants in 8,614 hips. The balanced cohort included all 10,205 procedures (54.2% female; age 65.5 [11.3]; 14.1% Elixhauser index ≥5; 84.5% MCTT, 82.2% other since 2018; obesity 43.6% MCTT, 43.0% other). Two-year revision was 0.9% for MCTT and 1.8% for other implants (p = .021). HR for revision MCTT vs. other was 0.53 (95% CI 0.30–0.92; p = .023). Mean (SD) OR time was 69.07 (18.93) minutes for MCTT, 83.69 (43.88) for other implants (p < .001). LOS was 1.99 (1.15) days for MCTT, 2.45 (2.91) for other implants (p < .001). MCTT patients were more likely to be discharged home (90.7% vs 33.8%, p < .001) and less likely to be discharged to skilled nursing facilities (SNF) (4.2% vs 9.6%, p < .001). One-year cost savings per patient with MCTT was projected at $2,342. Conclusions MCTT patients had fewer revisions, reduced OR time, shorter LOS, more home and less SNF discharge, leading to cost savings.

Can severity of trunnion damage be estimated by visual inspection alone?

Taper corrosion has been widely reported to be problematic for modular total hip arthroplasty implants. A simple and systematic method to evaluate taper damage with sufficient resolution is needed. We introduce a semiquantitative grading system for modular femoral tapers to characterize taper corrosion damage. After examining a unique collection of retrieved cobalt-chromium (CoCr) taper sleeves (n = 465) using the widely-used Goldberg system, we developed an expanded six-point visual grading system intended to characterize the severity, visible material loss, and absence of direct component contact due to corrosion. Female taper sleeve damage was evaluated by three blinded observers using the Goldberg scoring system and the expanded system. A subset (n = 85) was then re-evaluated following destructive cleaning, using both scoring systems. Material loss for this subset was quantified using metrology and correlated with both scoring systems. There was substantial agreement in grading among all three observers with uncleaned (n = 465) and with the subset of cleaned (n = 85) implants. The expanded scoring criteria provided a wider distribution of scores which ultimately correlated well with corrosion material loss. Cleaning changed the average scores marginally using the Goldberg criteria (p = 0.290); however, using the VGS, approximately 40% of the scores for all observers changed, increasing the average score from 4.24 to 4.35 (p = 0.002). There was a strong correlation between measured material loss and new grading scores. The expanded scoring criteria provided a wider distribution of scores which ultimately correlated well with corrosion material loss. This system provides potential advantages for assessing taper damage without requiring specialized imaging devices.

EVALUATION OF PROXIMAL FEMORAL BONE MINERAL DENSITY IN CEMENTLESS TOTAL HIP ARTHROPLASTY: A THREE-ARM PROSPECTIVE RANDOMIZED CONTROL TRIAL

Femoral stem design affects periprosthetic bone mineral density (BMD), which may impact long term survival of cementless implants in total hip arthroplasty (THA). The aim of this study was to examine proximal femoral BMD in three morphologically different uncemented femoral stems designs to investigate whether one particular design resulted in improved preservation of BMDMethods: 119 patients were randomised to receive either a proximally coated dual taper wedge stem, a proximally coated anatomic stem or a fully coated collarless triple tapered stem. All surgeries were performed via the posterior approach with mobilization on the day of surgery. Dual energy x-ray absorptiometry scans (Lunar iDXA, GE Healthcare, Madison, WI) assessed BMD across the seven Gruen zones pre-operatively, and post-operatively at 6-weeks, 1-year, and 2-years and compared to the unoperated contralateral femur as a control. Patient reported outcome measures of pain, function and health were also included at these corresponding follow-ups.BMD increased in zones one (2.5%), two (17.1%), three (13.0%), five (10%) and six (17.9%) for all stems. Greater preservation of BMD was measured on the lateral cortex (zone 2) for both the dual taper wedge and anatomic stems (p = 0.019). The dual taper wedge stem also demonstrated preservation of BMD in the medial calcar (zone 7) whilst the anatomic and triple taper stem declined in this region, however this was not statistically significant (p = 0.059). BMD decreased on average by 2.1% inthe mid-diaphysis region, distal to the stem tip (zone 4) for all implants. All stems performed equivalently at final follow-up in all patient reported outcome measures.This study demonstrated maintenance of femoral BMD in three different cementless femoral stem designs, with all achieving excellent improvements in patient reported outcomes. There was no significant stress shielding observed, however longer follow-up is required to elucidate the impact of this finding on implant survivorship.