Large-diameter Head Research Articles

The role of femoral head size in metal-on-metal hip arthroplasty: analysis of a cohort of 3813 patients with long term follow-up

Metal-on-metal (MoM) large headed arthroplasties were suggested to decrease failure rates by means of reduced volumetric wear and enhanced implant stability. However, they caused high rates of revisions due to adverse reaction to metal debris, osteolysis, pseudotumor growth, and other issues. The study aims to present the long-term outcomes of MoM arthroplasties on a large cohort of patients, evaluating the impact of head sizes on survival rate. All data were retrieved from the regional joint register (Registro dell’Implantologia Protesica Ortopedica, RIPO, Italy). We include in the study all patient who underwent cementless MoM total hip arthroplasties (THAs) between 2000 and 2020, dividing them in two subgroups according to head size (<36 mm, ≥36 mm). Failures were recorded up to December 31, 2020. Patients lost to follow-up were excluded. A total of 3813 THAs met the inclusion/exclusion criteria. The average follow-up period is 12.4 years (0–21 years). 178/1625 (or 11.0%) small head MoM THAs and 265/2188 large head ones failed by the end of follow up. Large diameter heads reported lower survival rate (p-value < 0.001), with unexpected higher dislocation rate (1.0 vs. 0.4%). Moreover, large head size was found to increases the risk of metallosis (p-value < 0.0001). Gender, patient’s age and the use of modular neck were not correlated with higher failure rates. MoM implants implants do not have the same reliability as other couplings, considering the significantly greater failure/complication rates. However, the knowledge of risks linked to head size is fundamental for establishing the right type of follow-up to the patient and recognize any complications early.

Correlation of radiological parameters with functional outcomes post fixation with proximal humerus locking plates.

Proximal humerus fractures account for 4-5% of all fractures in adults and affect females more than males. With the advent of special locking plates, the treatment trend has shifted more towards a surgical approach. These methods have produced good results but very high complications rates have been reported in the literature. This study was undertaken to analyse the radiological parameters which reflect towards a favourable long term functional outcome in order to advance the surgical fixation skills for managing fractures of the proximal part of the humerus. 83 study participants with proximal humerus fracture fixed using proximal humerus locking plates were retrospectively analysed. The radiological parameters studied were neck shaft angle, head shaft angle, head diameter, head height, greater tuberosity to articular surface distance and reduction of the medial hinge with or without placement of calcar screw. The functional parameters assessed were the Constant Murley Score and range of movements of the shoulder joint. The patients were not followed further for the purpose of the study. The mean Constant Murley Score for the participants was 80.75 ± 8.09 (range 60-90). The participants with good to excellent CM Score had a significantly higher neck shaft angle (107.47 ± 9.74 v/s 124.16 ± 10.68) and (-0.28 ± 0.85 v/s 2.37 ± 2.28), head shaft angle (23.09 ± 4.82 v/s 31.76 ± 7.76), head diameter (40.08 ± 8.63 v/s 45.15 ± 4.73), head height (18.77 ± 1.96 v/s 20.69 ± 2.76) and greater tuberosity to articular surface distance (-0.28±0.85 v/s 2.37±2.28) as compared to the patients with satisfactory and worse CM Score. The patients with a higher neck shaft angle and a maintained subacromial space had a better range of shoulder abduction. A higher rate of valgus collapse was seen with an inadequate medial hinge reduction. The radiological parameters which can predict towards a good functional outcome are a higher neck shaft angle and head shaft angle, a larger head diameter and head height, a superior position of the greater tuberosity in relation to the articular surface and a good medial hinge reduction.

Excellent Results of Large-Diameter Ceramic-On-Ceramic Bearings in Total Hip Arthroplasty at Minimum Ten-Year Follow-Up

BackgroundThis study reports the minimum 10 years results of total hip arthroplasty (THA) performed using a monoblock acetabular component with a large-diameter head ceramic-on-ceramic bearing. MethodsOf the 276 THAs included in this study, there were eleven deaths and 27 patients lost to follow up (11%) during the follow-up, leaving 237 (85%) hips available for review at a mean of 10.5 years (range, 10 to 12) postoperatively. Reoperations, implant revisions, adverse events, clinical outcomes, radiographic evaluation, and whole blood metal ion levels were assessed at the last follow-up. ResultsAfter a minimum of 10 years, implant survivorship was 98.7%. There were 3 revisions (1.3%): one for insufficient acetabular cup primary fixation, one traumatic periprosthetic acetabular fracture, and one probable deep chronic infection. No dislocation or ceramic implant fracture was observed. The mean University of California at Los Angeles activity score, Western Ontario and McMaster Universities Osteoarthritis Index score, and Forgotten Joint Score were 5.6 (2 to 10), 90.1 (9 to 100), and 79.2 (4 to 100), respectively. All patients (100%) were satisfied or very satisfied. Since implantation, 43% of patients reported hearing a squeaking noise from the prosthesis. But all patients who reported squeaking were satisfied with the surgery. The mean titanium level was 2.2 μg/L (1.1 to 5.6). No progressive radiolucent lines, osteolysis, or implant loosening signs were observed at the last radiographic evaluation. ConclusionsA large-diameter head ceramic-on-ceramic THA provides outstanding long-term (minimum 10 years) implant survivorship with unrestricted activity while avoiding implant impingement, liner fracture, and hip instability. Functional outcomes, satisfaction, and joint perception were excellent. Although the incidence of squeaking was high, it did not affect patient satisfaction or function. The systemic titanium levels were low, related to unavoidable passive corrosion of implant surfaces, and did not reveal any indirect signs of trunnionosis.

CORRELATION AND REGRESSION ANALYSIS IN DIFFERENT GENOTYPES OF SUNFLOWER (HELIANTHUS ANNUUS L.)

In 2017, a study at the Oil Seeds Research Section in Tandojam analyzed growth and yield across eight sunflower genotypes: Corolla, Melbour, Vulgare, Turkish, Samson-30, Sputnik, HO-1, and Parson. Using a randomized complete block design with three replications, significant variations were discovered in days to flowering and maturity, plant height, head diameter, number of seeds per head, seed yield, and seed index, emphasizing the distinct performance of each genotype. Advanced genotypes like Sputnik and HO-1 required more days to flower, with Parson and Sputnik showing the latest maturity. Turkish plants were notably taller, while Parson had the shortest stature. Parson and HO-1 stood out with larger head diameters and higher seed indexes, with Parson also leading in seed yield, suggesting their high breeding value. Positive correlations among various growth and yield parameters underscore the potential of these genotypes in breeding programs aimed at improving sunflower yields. This concise analysis highlights the diversity and breeding prospects within sunflower genotypes, offering valuable insights for future genetic improvement efforts.

Growth and Yield of Sunflower under the Integrated Farmyard Manure and Potassium Fertilization

The study was conducted during the autumn of 2022 Session at the Students' Experimental Farm Department of Agronomy, Sindh Agriculture University Tandojam, using a Randomized Complete Block Design. Objective: To assess how varying levels of Farmyard Manure and potassium affect the growth and seed production of sunflowers. Methods: The study utilized five different Farmyard Manure treatments and three potassium stages. The variety HO-1 underwent the following treatments: T1 = Control (0-ton Farmyard Manure+ 0 kg ha-1 potash), T2 = 5-ton Farmyard Manure+ 30 kg ha-1 potash, T3 = 5-ton Farmyard Manure+ 60 kg ha-1 potash, T4 = 5-ton Farmyard Manure+ 80 kg ha-1 potash, T5 = 5-ton Farmyard Manure+ 120 kg ha-1 potash. Results: The best results were found in T5 (5 tons of Farmyard Manure + 120 kg ha-1 Potash), which had the largest plant girth (11.2 cm), largest head diameter (48.5 cm), tallest plant (247.4 cm), highest number of seeds per head (1971.3), heaviest seed weight (69.5 g) per head, seed index (34 g), and maximum seed yield (2725.7 kg ha-1). T4 closely trailed, showing positive results (5 tons of farmyard manure plus 80 kg ha-1 potash). Conclusions: In conclusion, the study demonstrates that the optimal combination for maximizing sunflower growth and yield is the application of 80 kg ha-1 of potassium and 5 tons of Farmyard Manure.

Computer-based analysis of the taper connection strength of different revision head and adapter sleeve designs.

Ceramic revision heads, equipped with titanium adapter sleeves, are used in femoral head revision in total hip arthroplasty to avoid ceramic fracture due to the damaged taper. A finite element analysis of the taper connection strength of revision heads with varying head diameters combined with adapter sleeves of different lengths was conducted. The influence of various assembly forces, head diameter, and length of the adapter sleeves was evaluated. For two combinations, the pattern of contact pressure was evaluated when applying a simplified joint load (3 kN, 45° load angle). Experimental validation was conducted with 36 mm heads and adapter sleeves in size S, as well as 28 mm heads and adapter sleeves in size XL. The pull-off force increased with higher assembly forces. Using larger head diameters and adapter sleeves led to decreased pull-off forces, a reduced contact surface, and less contact pressure. The contact pressure showed significant peaks and a diagonal pattern under 45° angle loading when assembly forces were less than 4 kN, and larger adapter sleeves were utilized. A sufficient assembly force should be ensured intraoperatively, especially with an increasing head diameter and adapter sleeve size, as lower assembly forces might lead to reduced taper connection strength.

Evolution of Concepts: Can Personalized Hip Arthroplasty Improve Joint Stability?

Hip arthroplasty procedures are successful and reproducible. However, within the first two post-operative years, hip dislocations are the most common cause for revisions. This is despite the majority of the dislocations having the acetabular component within what is described as the 'safe zone'. The limitations of such boundaries do not take into account the variability of individual hip anatomy and functional pelvic orientation that exist. An alternative concept to address hip instability and improve overall outcomes is functional acetabular orientation. In this review article, we discuss the evolution of concepts, particularly the kinematic alignment technique for hip arthroplasty and the use of large-diameter heads to understand why total hip arthroplasty dislocations occur and how to prevent them.

Metal-on-Metal Hips: Ten-Year Clinical and Radiographic Outcomes of the ADEPT Metal-on-Metal Hip Resurfacing and Modular Total Hip Arthroplasty.

The aim of this study is to update the 10-year follow-up survivorship and metal ions levels of a cohort of metal-on-metal (MoM) hip resurfacing (HR) and large-diameter-head (LDH) total hip arthroplasty (THA). The study is a retrospective analysis of prospectively collected data that compared the outcomes of 24 MoM HR (21 patients) and 15 (11 patients) modular LHD MoM THA at >10 years follow-up. Baseline characteristics as well as intraoperative and postoperative information were collected, including complications, revisions, clinical and radiographic outcomes, and serum metal ions level (Cobalt, Chromium). Metal ion levels were compared using a two-tailed unpaired t-test and Wilcoxon signed-rank test (jamovi v2.3.3.0, Sydney, NSW, AU). No significant differences were detected in gender, BMI, and ASA score between the two groups. Patients in the modular THA group were significantly older (57 years vs. 46 years; p < 0.05). The HR overall survivorship was 91.7% (22 of 24 hips) with survivorship from implant failure and/or aseptic loosening and/or metal debris related 100% of problems. The modular THA overall survivorship was 86.7% (13 of 15 hips) with survivorship from implant aseptic loosening and metal ions complications of 93.4% (14 of 15 hips). No significant difference was noted when comparing clinical outcomes. Metal ions were significantly lower in the HR group (Co 25.8 nmol/L vs. 89 nmol/L; p < 0.001-Cr 33.5 nmol/L vs. 55.2 nmol/L; p = 0.026). Both implants reported excellent and comparable clinical outcomes at >10 years follow-up. The Adept HR reported remarkable survivorship, in line with the registry data, proving once again its reliability in young active males. The modular LDH THA, despite being discontinued, presented higher reliability and a lower failure rate when compared with similar withdrawn MoM implants. Trunnionosis did not appear to be a significant problem in this particular modular design.

What's New in Musculoskeletal Tumor Surgery.

What's New in Musculoskeletal Tumor Surgery.

Monobloc press-fit cups with large-diameter bearings are safe in revision total hip arthroplasty.

Instability is a major cause of failure of revision total hip arthroplasty (THA) which can be avoided with the use of monobloc press-fit cups with large diameter heads (LDH). This consecutive case series analyses whether LDH monobloc components are a safe and clinically beneficial option for revision THA. This consecutive case series includes 47 revision THA with LDH monobloc acetabular cup. Acetabular bone defects were Paprosky type I (42), type IIA (2) and type IIC (3). The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Forgotten Joint Score (FJS) and the Patient's Joint Perception (PJP) scores were analysed and a radiographic evaluation for signs of implant dysfunction was performed. After a mean follow-up of 4.5 years, there were 5 (10.6%) acetabular cup re-revisions: 2 loss of primary fixation and 3 instabilities. Implant survivorship at 4-years was 89.4% (95% CI: 89.3 to 89.5). Recurrent hip dislocation was reported in 1 patient (2.1%) and remains under conservative treatment. The mean WOMAC and FJS were 19.5 (16.8; 0.0 to 58.3) and 57.3 (28.9; 6.3 to 100.0), respectively. Regarding the PJP, 3 (8.8%) patients perceived their hip as natural, 8 (23.5%) as an artificial joint with no restriction, 14 (41.2%) with minor restriction and 9 (26.5%) with major restriction. In cases of revision THA with limited bone loss, press-fit primary fixation with LDH monobloc acetabular components are valuable options that offer excellent mid-term out-comes with low re-revision and joint instability rates.

Long-term survival analysis of cementless large-diameter head metal-on-metal total hip arthroplasty

IntroductionThe aim of this retrospective study was to study the long-term survival and reasons for revisions of a single-type, large-diameter head (LDH) metal-on-metal (MoM) implant. A special study interest was to find the threshold level for revision in terms of adverse reaction to metal debris (ARMD).Materials and MethodsIn this cohort study, we retrospectively reviewed 234 patients (253 hips) who received 38 mm head size LDH MoM total hip arthroplasties (THAs) between 01 January 2004 and 31 December 2009 at our institution. Patient symptoms, conventional radiographs, magnetic resonance imaging (MRI) findings and whole blood metal ions were studied.ResultsThe median follow-up time was 11.5 years. The Kaplan–Meier cumulative survival estimate of the implant was 89.6% at 10 years and 82.9% at 14.6 years. Overall, 34/253 (13.4%) hips were revised during the follow-up period and of these; 19/34 (55.9%) were revised due to ARMD. The prevalence of ARMD was 12.4% (29/234 patients).ConclusionsThe survival of the implant was on a moderate level as the 10-year cumulative survival rate was 89.6%. The exact threshold level for ARMD revision cannot be determined due to multiple variables affecting factors in re-operation decision-making.

Primary THA Using Thin Polyethylene Liners and Large Femoral Heads: A Minimum 5-Year Follow-Up.

Large femoral head sizes are commonly used in total hip arthroplasty (THA) to minimize the risk of instability. With small acetabular cup-size, large femoral head diameter often results in the use of thin polyethylene liners. The purpose of this study was to evaluate clinical and radiographic results of large femoral heads against thin polyethylene liners with minimum 5-year follow-up. This was a retrospective review identifying 58 primary THAs utilizing thin polyethylene inserts from one manufacturer (X3 polyethylene, Stryker, Mahwah, NJ) and large femoral heads (36 mm or greater) with minimum 5-year follow-up. A total of 3 patients were deceased and 11 lost to follow-up, leaving 44 patients for review. All patients were female with mean age 65.7 (range 26-85) and mean body mass index (BMI) 29.9 (range 19.6-45.4). Average length of follow-up was 8.5 years (range 5.1-11.3). Outcome measures included survivorship, complications, PROMs and radiographic analysis. There were four revisions: two aseptic loosening, one prosthetic joint infection, and one recurrent dislocation. Average HOOS-Jr, FJS-12, and patient satisfaction using Likert score was 94.3/100, 92.9/100, and 4.69/5.00, respectively, with 94% of patients reporting being satisfied or very satisfied. Radiographic analysis at average of 8.5 years demonstrated well-fixed implants without evidence of progressive radiolucent lines, osteolysis, or failure of the polyethylene liner. Survivorship using failure of the thin polyethylene liner as the endpoint was 100% at an average of 8.5 years. Thin polyethylene liners used with large femoral head sizes in small acetabular cups demonstrated excellent results at average 8.5-year follow-up with no cases of liner fracture or osteolysis.

Influence of nitrogen level and plant density on growth parameters and economic efficiency of sunflower cultured in Thua Thien Hue province

Sunflower (Helianthus annuus) cultivation is gaining popularity among Vietnamese farmers. Two separate experiments were conducted from January to April 2018 in a randomized complete block design with three replicates. Four levels of each factor were included in the experiments: 0, 20, 40, and 60 kg/ha for nitrogen and 11, 13, 16, and 20 plants/m2 for the density. The nitrogen fertilizer (up to 60 kg/ha) substantially affects the leaf area, diameters of stem plant, receptacle and flower head, and cut flower vase life. Low plant density works well on plant height, leaf number, width and length at the flowering stage, with the largest head diameter (17.2 cm) at the 13 plants/m2 density. Based on the results of both growth ability and economic efficiency, we suggested applying N at 60 kg/ha and planting at 16 plants/m2 density for growing F1 cut sunflowers in Thua Thien Hue province.

Median 10-year whole blood metal ion levels and clinical outcome of ReCap-M2a-Magnum metal-on-metal total hip arthroplasty.

Background and purposeWe have previously reported that the whole blood (WB) chromium (Cr) and cobalt (Co) ion levels decrease in the short term after ReCap-M2a-Magnum large-diameter head (LDH) metal-on-metal (MoM) total hip arthroplasty (THA). This study reports long-term metal ion levels and clinical outcomes after ReCap-Magnum THA.Patients and methodsReCap-M2a-Magnum LDH THA was used in 1,450 patients in our hospital district from 2005 to 2012. Median follow-up time was 10 years. 991 patients had 2 or more metal ion measurements. The median measurement interval was 4 years. Individual metal ion change was assessed using logarithmic metal ion values in a random coefficient model. Kaplan–Meier survival estimates were calculated for revision surgery for any reason for revision, and separately for metal-related adverse events (metal ions above safe upper limit [SUL], revision due to ARMD, or pseudotumor).ResultsGeometric mean of Cr decreased from 1.8 ppb (geometric standard deviation [GSD] 1.8) to 1.0 ppb (GSD 2.8, p < 0.001). The Co levels decreased from 1.7 ppb (GSD 2.4) to 1.4 ppb (GSD 2.8, p < 0.001). The hip-specific survival was 85% for revision due to any reason at 14 years and the hip-specific survival for any metal-related adverse event was 69% at 14 years.InterpretationWB Cr and Co levels continued to decrease in the long-term follow-up of ReCap-M2a-Magnum THA patients. The amount of metal-related adverse events was rather high, but revision surgery was seldom required. We suggest that after 10 years from the implantation a 5-year measurement interval may be sufficient for asymptomatic ReCap-M2a-Magnum patients.

Personalized Hip Joint Replacement with Large Diameter Head: Current Concepts.

Hip arthroplasty is a common procedure in elective orthopaedic surgery that has excellent outcomes. Hip replacement surgery aims to create a “forgotten” joint, i.e., a pain-free joint akin to a native articulation. To achieve such goals, hip arthroplasty must be personalised. This is achieved by restoring: the centre of rotation of the native hip; leg length equality; femoral offset; femoral orientation; soft tissue tension; joint stability with an unrestricted hip range of motion; and having appropriate stress transfer to the bone. In addition, the whole pathway should provide an uneventful and swift postoperative recovery and lifetime implant survivorship with unrestricted activities. At our institution, the preferred option is a personalized total hip arthroplasty (THA) with a large diameter head (LDH) using either monobloc or dual-mobility configuration for the acetabular component. LDH THA offers an impingement-free range of motion and a reduced risk of dislocation. The larger head-neck offset allows for a supraphysiologic range of motion (ROM). This can compensate for a patient’s abnormal spinopelvic mobility and surgical imprecision. Additionally, LDH bearing with a small clearance exerts a high suction force, which provides greater hip micro-stability. With appropriate biomechanical reconstruction, LDH THA can restore normal gait parameters. This results in unrestricted activities and higher patient satisfaction scores. We use LDH ceramic on ceramic for our patients with a life expectancy of more than 20 years and use LDH dual mobility bearings for all others.

Liner dissociation in a large-diameter ceramic-bearing acetabular component: a report of five cases

BackgroundCeramic-on-ceramic (CoC) bearings for total hip arthroplasty (THA) have been offering very favorable results and survivorship since their introduction. In order to increase range of movement (ROM) and decrease dislocation rates, some manufacturers have introduced larger diameter head (LDH) CoC bearings. This has been achieved with the use of preassembled cup designs, in which the ceramic liner is already fitted into the metal backing and implanted as a monoblock component by the surgeon. In this report we present data from a series of 5 patients with ceramic liner dissociation from a monoblock cup.Case presentationAll cases were overweight men with acetabular components of 56 or 58 mm. After a mean of 5.5 (range, 3.5-6.7) years, all patients reported sudden pain and audible noise when performing activities of daily living. Liner displacement was suspected on plain radiographs and confirmed by Ct-scan. Pneumarthrosis was present in all cases. Taper modular junction wear and corrosion signs were observed in the four revised patients.ConclusionAlthough one of our case is still treated conservatively, implant revision is probably inevitable. Further LDH CoC implant design should take in consideration this potential complication by avoiding bearing diameters over 40mm and/or improving locking mechanism or by providing a real monoblock acetabular implant.

IMPACT OF VARIOUS PRESERVATIVE SOLUTIONS ON VASE LIFE AND POST-HARVEST QUALITY OF CUT ROSES

Short vase life and post-harvest losses of cut flowers are major threat to floriculture industry. There are different preservative solutions that have been used to extend the post-harvest life of cut flowers. Hence, this study was executed at Floriculture laboratory of Ayub Agricultural Research Institute, Faisalabad during 2018-2020 to explore the efficacy of different preservative solutions on vase life and post-harvest quality of cut roses. There were 6 treatments viz, (T1= Distilled water, T2= Silver nitrate @ 100 ppm, T3= 8-Hydroxyquiroline citrate @ 100 ppm, T4= Sodium thiosulphate @100 ppm, T5= Sodium benzoate @100 ppm, T6= Sucrose @ 40 g/L) and two rose cultivars Kardinal and Gold medal. The experiment was arranged according to complete randomized design (CRD). Results designated that longest vase life (15 days), maximum soluble solid contents (9.3 Brix) and longest opening period (7.4 days) were acquired with silver nitrate @100 ppm solution while maximum flower size (6.77 cm2) and largest head diameter (8.6 cm) were achieved with sodium thiosulphate when applied at the rate of 100 ppm in cultivar Kardinal. All other chemical solutions also displayed positive effects. Keeping in view the remarkable impact of Silver nitrate on vase life and quality of cut roses, it is recommended for commercial growers and cut flower industry for preservation of cut roses for longer time.

Performance of Lettuce (Lactuca Sativa L.) Genotypes with Respect to Morphological, Yield and Quality Traits at Two Localities of Nepal

Lettuce is cultivated as minor crop in Nepal. However, people are becoming more health conscious in these days and demand for salad is increasing in food. The demand of lettuce is also gradually increasing but relatively few farmers are involved in this crop due to the lack of high-yielding and good quality genotypes. The research was conducted at two locations of Nepal; Kavre and Kaski with the aim of evaluating the performance of seven different hybrid lettuce genotypes in terms of its morphology, yield, and quality. The research was laid out on Randomized Complete Block Design with three replications at each location. Two types of lettuce were used on the research i.e. head type and leaf type. Among the head type, genotype Iceberg performed better with more plant spread (51 cm), head diameter (14.7 cm) and yield (738.4 g at Kavre and 725.8 g at Kaski) than other head type lettuce genotypes and among leaf type variety Green Oak was recorded with highest numbers of leaves (67 at Kavre and 40 at Kaski) and yield (572.3 g at Kavre and 641.9 g at Kaski). So, among head type lettuce genotypes Iceberg performed better as this had better plant spread, large head diameter, more yield and sweet flavor. Among leaf type genotypes Variety Green Oak was found most suitable for Nepali Market as this variety had highest number of leaves and yield among leaf type lettuce genotypes.

Effect of Bone Coverage on Acetabular Implant Stresses in Standard and Dual-Mobility Total Hip Arthroplasty Constructs: A Finite Element Model.

Although mechanical stress in total hip arthroplasty modular head-neck junctions is thought to contribute to the risk of trunnionosis and related metal ion disease in total hip arthroplasty, little is known about mechanical stress in the modular acetabular components. Recent retrieval analyses of dual-mobility constructs have demonstrated corrosion between liner and shell in some dual-mobility acetabular components. The objective of this study was to evaluate acetabular stress as a function of acetabular bone coverage, component modularity, and femoral head diameter. A parametric finite element model was created. The acetabulum was set at 40° of abduction and 15° of anteversion; superolateral bone loss up to 50° was modeled; and 28-mm, 32-mm, 36-mm, and 40-mm head sizes were simulated in stance phase of gait. Fixed polyethylene-bearing, monoblock and modular dual-mobility (MDM) acetabular components were evaluated. For traditional fixed-bearing components, the largest peak stress, 49.5 MPa, was observed with 50° of bone loss and a 28-mm head. The lowest peak stress, 6.3 MPa, occurred with complete bone coverage and a 36-mm head. Peak stress in the MDM construct, 25.1 MPa, concentrated in the chromium-cobalt portion of the construct. Larger head diameters are associated with decreased stress in the acetabular component when bone loss is present. An MDM construct with a stiff inner liner may decrease overall stress in the acetabular construct, but focally increased stress near the rim of uncovered acetabular components may increase the risk of metal-on-metal corrosion. [Orthopedics. 2021;44(5):280-284.].

Spinopelvic Biomechanics and Total Hip Arthroplasty: A Primer for Clinical Practice.

Abnormal spinopelvic motion from spine pathology is associated with inferior outcomes after total hip arthroplasty, including inferior patient-reported outcomes, increased rates of instability, and higher revision rates. Identifying these high-risk patients preoperatively is important to conduct the appropriate workup and formulate a surgical plan. Standing and sitting lateral spinopelvic radiographs are able to identify and quantify abnormal spinopelvic motion. Depending on the type of spinopelvic deformity, some patients may require increased anteversion, increased offset, and large diameter heads or dual mobility articulations to prevent dislocation. This review article will provide the reader with practical information that can be applied to patients regarding the terminology, pathophysiology, evaluation, and management of total hip arthroplasty patients with spinopelvic pathology.