To evaluate the predictive ability of AI HIP in determining the size and position of prostheses during complex total hip arthroplasty (THA). Additionally, it investigates the factors influencing the accuracy of preoperative planning predictions.

From April 2021 to December 2023, patients with complex hip joint diseases were divided into the AI preoperative planning group (n = 29) and the X-ray preoperative planning group (n = 27). Postoperative X-rays were used to measure acetabular anteversion angle, abduction angle, tip-to-sternum distance, intraoperative duration, blood loss, planning time, postoperative Harris Hip Scores (at 2 weeks, 3 months, and 6 months), and visual analogue scale (VAS) pain scores (at 2 weeks and at final follow-up) to analyze clinical outcomes.

On the acetabular side, the accuracy of AI preoperative planning was higher compared to X-ray preoperative planning (75.9% vs. 44.4%, P = 0.016). On the femoral side, AI preoperative planning also showed higher accuracy compared to X-ray preoperative planning (85.2% vs. 59.3%, P = 0.033). The AI preoperative planning group showed superior outcomes in terms of reducing bilateral leg length discrepancy (LLD), decreasing operative time and intraoperative blood loss, early postoperative recovery, and pain control compared to the X-ray preoperative planning group (P < 0.05). No significant differences were observed between the groups regarding bilateral femoral offset (FO) differences, bilateral combined offset (CO) differences, abduction angle, anteversion angle, or tip-to-sternum distance. Factors such as gender, age, affected side, comorbidities, body mass index (BMI) classification, bone mineral density did not affect the prediction accuracy of AI HIP preoperative planning.

Artificial intelligence-based 3D planning can be effectively utilized for preoperative planning in complex THA. Compared to X-ray templating, AI demonstrates superior accuracy in prosthesis measurement and provides significant clinical benefits, particularly in early postoperative recovery.

Dislocation is one of the debilitating complications of total hip arthroplasty. It is a common reason for revision surgery after THA, along with other complications such as infection and instability. This study determined the incidence and risk factors of dislocation after primary total hip arthroplasty using the direct anterior approach.

Retrospective Data from patients who underwent primary THA from 2013 to 2020 was analyzed. Anteversion and inclination angles were extracted from their imaging studies, and demographic data were also recorded from their medical records. Data were analyzed using SPSS version 26.

One thousand two hundred four cases of THA were reviewed in our study. 31 (2.57%) dislocations happened after a minimum follow-up of five years. Our study showed that DDH diagnosis as the underlying condition, using Wagner Cone and Wagner SL stem, cup size smaller than 52, head size smaller than 34, anteversion and inclination angle outside the Lewinnek safe zone can be risk factors for dislocation. Primary OA and Fitmore stem acted as protective factors for dislocation.

In the DA approach, the underlying disease, properties of the prosthesis used such as cup and head size, stem type, and anteversion and inclination angles can be the potential risk factors for dislocation.

III.

Preoperative templating is crucial when performing total hip arthroplasty (THA) as it facilitates the correct restoration of the joint biomechanics and reduces the risk of adverse events associated with component under- or over-sizing. Templating and execution of stem placement is highly dependent on the actual stem design. Therefore, we aimed to compare the templating adherence between a neck-resecting and a partially neck-sparing cementless short stem and to evaluate the influence of patient-specific factors like sex and Dorr type on the templating adherence.

This retrospective cohort study evaluated the preoperative templates of 345 consecutive THAs performed by a single surgeon. A neck-resecting short stem (Fitmore, ZimmerBiomet) combined with a bi-hemispherical cup (Allofit, ZimmerBiomet; Group A) was used in 160 cases and a partially neck-sparing short stem (ANA NOVA alpha proxy, ImplanTec GmbH) combined with a bi-hemispherical cup (ANA NOVA alpha cup, ImplanTec GmbH; Group B) in 185 cases. The templating adherence was evaluated for stem size and offset option as well as cup size.

Group A showed a lower overall templating adherence with regard to stem size compared to Group B (26.9% vs. 36.2% exact match, p = 0.063; 57.5% vs. 71.4% ± 1 size, p = 0.007). In female patients templating adherence with regard to stem size was significantly lower in Group A (26.5% vs. 44.4% exact match, p = 0.012). For Dorr type B femora, significantly lower templating adherence was observed within Group A with regard to stem size (26.4% vs. 39.6% exact match, p = 0.013). No significant differences between both study groups were found with regard to adherence to the templated offset option (60.6% vs. 60.5% exact match, p = 0.987) and cup size (43.1% vs. 40.0% exact match, p = 0.557).

For both stem types, the overall rate of exactly matching the templated stem sizes was relatively low. However, templating adherence was significantly higher in female patients and in Dorr type B femora with a partially neck-sparing stem, which should be considered by surgeons performing THA using cementless short stems.

This trial was registered at the local ethics committee (Registration Number: 1094/2023).

Rising costs in healthcare for total hip arthroplasty (THA) mean that new solutions must be considered, such as the use of single-use ancillaries (SUA). The goal of this study was to assess the accuracy of 2D templating in primary THA for the use of reduced-size SUA. Our hypothesis was that the accuracy of 2D templating in primary THA would be higher than 95%, give or take two sizes.

This single-centre prospective study included all primary THAs performed over two years. Templating was carried out using 2D templating on anteroposterior pelvic X-rays. The template sizes were compared to the implant sizes. The primary endpoint was the rate of coincidence between digitally templated estimates and the actual implant sizes. The secondary endpoint was the difference of accuracy based on patient parameters.

We analysed 512 cases of THA. Accuracy within two sizes was 96.9% for acetabular implants and 98.5% for femoral implants. Accuracy was below the 95% threshold only in patients under 55 and over 85 years old. A BMI above 30.0 kg/m2 significantly reduced accuracy but did not fall below the 95% threshold. The operated hip, the type of implant, and the operative indication did not significantly influence templating accuracy.

Using reduced-size SUA with five rasps and five reamers depending on template sizes means that THA can be performed in more than 95% of cases allowing the use of compact single use ancillaries.

To compare different types of short stems (SS) in terms of native hip geometry reproducibility, analyzing centrum-collum-diaphyseal angle (CCD) and femoral offset (FO). These parameters allow the SS to be adapted to patient's anatomy in order to ensure better functional outcomes in total hip arthroplasty (THA).

A total of 387 cases of SS met the inclusion criteria. CCD and FO were measured using MediCAD® software Version 6 in preoperative (preop-) and postoperative (postop-) X-rays at 6-12 months after surgery. Considering preop-CCD, the sample was divided into three groups: ≤ 124.9° (A); 125°-129.9° (B); and ≥ 130°(C). Preop- and postop-CCD and FO and the respective average difference (Δ) were examined considering the SS individually and within groups, to verify reproducibility of these parameters.

The SS considered were eight: Fitmore Zimmer, Pulchra Adler, TRIS Adler, Trifit Corin, Trilock Depuy, Actis Depuy, Profemur Microport, and SMF Smith&Nephew. Groups A, B, and C consisted, respectively, of 113, 124, and 150 cases. Considering all cases, there was a statistically significant (p < 0.05) increase in CCD and FO with surgery. Overall, Trifit and Trilock stems were the best in reproducing preop-CCD, Trifit itself followed by Pulchra and Profemur for preop-FO. In groups A and C, the reproduction of preop-CCD was better than preop-FO, in contrast in group B. With regard to preop-CCD reproduction, in group A Trifit and Pulchra, in group B Fitmore and Trifit, and in group C Fitmore and Pulchra were the best. Fitmore in group A, SMF in group B, Pulchra and Trilock in group C were the worst in reproducing preop-FO.

Each hip anatomy is unique, and reproduction of preop-CCD and preop-FO can be achieved with different SS characteristics. Accurate knowledge of the stems and performing correct preop- planning are crucial to allow the best restoration of the patient's native hip geometry in THA.

To investigate the impact of hip adduction and abduction on the femoro-epiphyseal acetabular roof (FEAR) index using conventional anteroposterior pelvic radiographs of patients with borderline hip dysplasia (BHD).

Patients with BHD (lateral center edge angle [LCEA] with values of 18° ≤ LCEA <25°) and who were subject to periacetabular osteotoym were selected from a consecutive retrospective cohort from January 2009 to January 2016. The hip ad-/abduction (adduction handled as negative values) and the FEAR index (lateral opening angles handled as positive values) were measured in the initially standardized acquired pelvic radiographs. Thereafter, using surgical planning software, different degrees of hip adduction and abduction were simulated from 20° of adduction to 30° of abduction, and the FEAR index was measured at each position. Pearson correlation was used to identify a potential correlation between the hip ad-/abduction and the FEAR index.

Eighty-nine hips were included. Initial radiographs showed unintentional mean ad-/abduction of -5.3° ± 3.1° (range, -14° to 2°). The mean FEAR index at the initial ad-/abduction angle was -3.6° ± 7.2° (range, -18.0° to 16.0°) and was significantly different from neutral position (0° of ad-/abduction) -9.2° ± 7.0° (range, -27.0° to 10.0°) (P < .001). The FEAR index was negatively correlated to the hip ad-/abduction angle (r = 1, P < .001), with lower values for the FEAR index with the hip in abduction.

Significant differences in FEAR index measurements were observed depending on hip ad-/abduction on pelvic radiographs. A linear change of the FEAR index of 5° per 5° of hip adduction or abduction could be demonstrated, with adduction resulting in increasing and abduction in decreasing values for the FEAR index.

Level III, diagnostic study.

Accurate preoperative planning is crucial for successful total hip arthroplasty (THA) for developmental dysplasia of the hip (DDH). The aim of this study was to compare the accuracy of an artificial intelligence-assisted three-dimensional (3D) planning system (AIHIP) with two-dimensional templates in predicting acetabular cup size in THA for DDH.

This study retrospectively analyzed image data from 103 DDH patients who had THA between May 2019 and August 2023. AIHIP was used for 3D planning, and two-dimensional (2D) templates were used by two experienced surgeons. Accuracy was assessed by comparing predicted and actual cup sizes, and potential factors affecting accuracy were analyzed, including gender, side, BMI, and dysplasia classification.

AIHIP had higher accuracy in predicting the acetabular cup size compared to the 2D template. Within ± 0 size, AIHIP's accuracy was 84.1%, while the 2D template's was 64.0% (p < 0.05). Within ± 1 size, AIHIP's accuracy was 95.1%, while the 2D template's was 81.1% (p < 0.05). Accuracy was unaffected by gender, side, or BMI but was by DDH classification. In subgroup analysis, AIHIP's mean absolute error (0.21 ± 0.54) was significantly lower than the 2D template's (0.62 ± 0.95) for Crowe II and Crowe III (p < 0.05).

AIHIP is superior to 2D templates in predicting the acetabular cup size accurately for THA in DDH patients. AIHIP may be especially beneficial for Crowe II and III DDH patients, as 2D templates may not accurately predict cup size in these cases.

This study aims to assess the outcome of total hip arthroplasty (THA) using artificial intelligence (AI)-assisted three-dimensional (3D) preoperative planning technology in terms of predicting prosthesis size, acetabular cup positioning, and lowerlimb length restoration.

Between January 2020 and July 2022, a total of 161 patients (101 males, 60 females; mean age: 57.6±10.5 years; range, 31 to 80 years) who underwent primary unilateral THA were retrospectively analyzed. The patients were divided into two groups as those who were treated with AI-assisted 3D preoperative planning technology (the observation group, n=95) and patients who were treated with traditional two-dimensional (2D) X-ray template planning technology (the control group, n=66).

The accuracy of the planning was based on the consistency of the preoperative planning and intraoperative models. The difference between the observation group and the control group was statistically significant in terms of the accuracy of the preoperative planning of acetabular prostheses (54% vs. 38%, p=0.048) and femoral prostheses (64% vs. 44%, p=0.011), with both values significantly higher in the observation group. The mean inclination angle, anteversion angle, and limb length discrepancy (LLD) in the observation group were 36.85°±4.82°, 12.10°±5.33°, and 2.18±2.70 mm, respectively, while those in the control group were 35.06°±6.07°, 10.95°±5.09°, and 4.42±3.85 mm, respectively. There was a statistically significant difference between the two groups in terms of inclination angle and LLD (p<0.05 for both), but there was no significant difference in terms of anteversion angle (p>0.05). In the observation group, 86.3% (82/95) of acetabular cups were implanted within the Lewinnek safe zone (72.7% [48/66] in the control group), while 83.2% (79/95) were within the Callanan safe zone (69.7% [46/66] in the control group), with both values higher in the observation group (p<0.05).

Overall, AI-assisted 3D preoperative planning is superior to traditional 2D X-ray template planning for predicting prosthesis size, and it also has the advantage in terms of acetabular cup positioning and lower-limb length restoration.

Fibrous dysplasia (FD) is a benign neoplasm with a broad spectrum of presentations. The treatment of FD in the hip region is controversial among orthopedic surgeons. Several treatment options exist, including curettage and grafting, valgus osteotomy, medial displacement osteotomy, and so on. Performing total hip arthroplasty (THA) on these patients and their subsequent outcome is still in infancy.

The patient is a 32-year-old white female with bilateral proximal femur FD who underwent bilateral THA with long stem implants. A year following surgery, she had no complications and had satisfactory radiological, pain, and functional outcomes.

A bilateral THA with a long stem prosthesis showed promising results when performed following appropriate curettage of the proximal bone in an FD case. A cementless long stem could have enabled better diaphyseal fixation distal to the lesion site.

This article aimed to explore the efficacy of robotic arm-assisted total hip arthroplasty (THA) in improving preoperative planning and intraoperative decision-making.

In this single-center, prospective, randomized clinical controlled trial, 60 patients were randomly divided into two groups: conventional THA (cTHA) and robotic arm-assisted THA (rTHA). The rTHA underwent procedures using a robot-assisted surgical system, which generated three-dimensional models to determine the most appropriate prosthesis size and position. The standard process of replacement was executed in cTHA planned preoperatively via X-ray by experienced surgeons. Differences between predicted and actual prosthetic size, prosthetic position, and leg length were evaluated.

Sixty patients were included in the study, but one patient was not allocated due to anemia. No significant preoperative baseline data difference was found between the two groups. The actual versus predicted implantation size of both groups revealed that 27/30 (90.0%) in the rTHA group and 25/29 (86.2%) in the cTHA group experienced complete coincidence. The coincidence rate for the femoral stem was higher in the rTHA group (83.3%) than that in the cTHA group (62.7%). Between the actual and predicted rTHA, the difference in anteversion/inclination degree (< 6°) was largely dispersed, while cTHA was more evenly distributed in degree (< 9°). The differences in leg length between the surgical side and contralateral side showed a significant deviation when comparing the two groups (P = 0.003), with 0.281 (- 4.17 to 3.32) mm in rTHA and 3.79 (1.45-6.42) mm in cTHA.

Robotic arm-assisted total hip arthroplasty can be valuable for preoperative planning and intraoperative decision-making.

Background​ Digital templating is an essential part of preoperative planning in elective total hip replacement (THR) surgery. The goals of templating are to predict femoral and acetabular implant sizes, to assess leg length, offset, and implant positioning. Templating markers such as the KingMark device (Brainlab, Munich, Germany) have been developed to improve the accuracy. Although templating is commonly used in many centres, there are challenges related to the accuracy of the process, such as true magnification ideal positioning of the pelvis and hips/body habit (obesity). Objectives The aim of this study was to assess the accuracy of preoperative templating in THR patients, and to assess the difference between templating performed with and without the KingMark device. Methods​ Our retrospective study included 642 consecutive patients who had primary THR at the Royal Bournemouth Hospital in the UK. Four hundred fifty-three (71%) of patients had the KingMark device on their templated radiographs. Patients who had hybrid total hip replacements using an uncemented acetabular component and cemented femoral component were included in the study. Digital templating was done using TraumaCad software (Brainlab). Analysis of the accuracy of predicting component size has been evaluated by comparing preoperative planned sizes with implanted sizes as documented by the surgeons and labels attached to the operative note. ​ ​Results​ The templated size corresponded to the actual femoral implant used in approximately 65.2% of cases. When femoral prostheses within one size above or below the templated size were included,​the accuracy of preoperative templating rose to 97.2%. Regarding the uncemented acetabular component, the templated size corresponded to the actual acetabular implant used in 46.3% of cases. When acetabular cup within one size above or below the templated size were included, the accuracy of preoperative templating rose to 87.5%. Similarly, there was minimal difference between the predicted templated sizes using the KingMark device compared to templating performed without it. ​Conclusions​ Preoperative templating is an essential part in optimizing the outcome of THRs. Templating allows the surgeon to estimate the size of the components to be used. It also provides a starting point, from which the surgeon can proceed from, and saves valuable intraoperative time by assessing the level of the femoral neck osteotomy and the degree of lateral rasping. Multiple factors affect the accuracy of preoperative templating including the patient BMI, external rotation of the hip and surgeon's experience. Although there are different methods of templating, digital templating with 2D radiographs is likely the most cost-effective and efficient process available at this time.

Pelvic obliquity (PO) has not been extensively investigated, and there is no gold standard for measurement. The PO is essential for surgeons in planning hip arthroplasty, which includes the restoration of leg length discrepancy (LLD). We aimed to establish a normative range of PO angles by measuring healthy individuals without musculoskeletal disorders.

Our study included 134 consecutive cases (70 females) referred to our institution between April 2020 and September 2021 for non-orthopedic problems. Patients were screened for normal gait and posture using the visual observation method (VOM) and the Modified Gait Abnormality Rating Scale (GARS-M). In standing standard radiographs, the PO angle was measured as the angle between the horizontal plane and the inter-teardrop line.

Patients' mean age and Body Mass Index (BMI) were 39.7 ± 16.8 and 22.3 ± 3.1, respectively. PO angles did not follow a normal distribution, with a median (IQR) of 2.0° (0.9°-3.1°). According to the Wilcoxon one-sample test, the median PO angle differed significantly from zero (P < 0.001). The PO angle did not differ significantly between males and females (2° vs. 2°, P = 0.46), nor did it correlate significantly with age (P = 0.24). Considering the 95% percentile of PO angles was 5.6°, this range (0°-5.6°) was regarded as a normative value.

Normative values for PO in the normal healthy population range from 0° to 5.6°, with a median value of 2.0°. The PO angle was independent of age and sex and differed significantly from 0°. Slight pelvic obliquity may be normal, and physicians should not always assume that it is caused by pain, scoliosis, or weakness of the abductors.

III.

Since Aspirin's adverse effects are dose-dependent, and evidence supporting the use of low-dose (LD) Aspirin in preventing venous thromboembolism (VTE) after total hip arthroplasty (THA) is weak, the authors do not know what the minimal effective dosage of Aspirin is to prevent VTE. This study aimed to compare the rates of 90-day symptomatic VTE following THA and total knee arthroplasty in healthy patients taking LD Aspirin vs. high-dose (HD) Aspirin for 6 weeks postoperatively.

A prospective cohort of patients with THA and total knee arthroplasty was conducted at two tertiary centres. Symptomatic VTE within 90 days of index arthroplasty was the primary outcome; gastrointestinal bleeding (GIB) and mortality were secondary outcomes.

The final analysis included 312 consecutive patients: 158 in the LD group and 154 in the HD group. Two groups were similar regarding preoperative data, including sex, age, BMI, smoking, diabetes mellitus, Hgb and platelet count, and type of surgery. The LD group had one deep vein thrombosis (0.6%), and the HD group had two (1.3%) (P=0.62). Neither group had PTE. Therefore, VTE rates are the same as deep vein thrombosis rates and similar between the groups (0.6% vs. 1.3%, P=0.62)Regarding GIB due to anticoagulant therapy, no patient in the LD group reported GIB, whereas two (1.3%) patients in the HD group reported GIB within 90 days of arthroplasty. GIB rates did not differ significantly between groups (P=0.24). Considering VTE + GIB combined, the HD groups showed a higher rate of complications (N=4, 2.6%) than the LD groups (N=1, 0.6%) but not statistically significant (P=0.21).

Prophylactic administration of Aspirin with low doses (81 mg BID) and high doses (325 mg BID) for six weeks is equally effective at reducing VTE in total joint arthroplasty patients and had similar adverse effects.

Therapeutic Level II.

Preoperative digital templating is a standard procedure that should help the operating surgeon to perform an accurate intraoperative procedure. To date, a detailed view considering gender differences in templating total knee arthroplasty (TKA), stage of arthrosis, and the surgeons' experience altogether has not been conducted.

A series of 521 patients who underwent bicondylar total knee arthroplasty was analyzed retrospectively for the planning adherence of digital templating in relation to sex, surgeon experience, and stage of arthrosis. Pre- and postoperative X-rays were comparably investigated for planned and implanted total knee arthroplasties. Digital templating was carried out through mediCAD version 6.5.06 (Hectec GmbH, 84032 Altdorf, Germany). For statistical analyses, IBM SPSS version 28 (IBM, 10504 Armonk, NY, US) was used.

The general planning adherence was 46.3% for the femur and 41.8% for the tibia. The Mann-Whitney U test revealed a gender difference for templating the femur (z = -5.486; p ≤ 0.001) and tibia (z = -3.139; p = 0.002). The surgeon's experience did not show a significant difference through the Kruskal-Wallis test in the femur (K-W H = 4.123; p = 0.127) and the tibia (K-W H = 2.455; p = 0.293). The stage of arthrosis only revealed a significant difference in the planning of the femur (K-L-score (K-W H = 6.516; p = 0.038) alone.

Digital templating for total knee arthroplasty brought up gender differences, with oversized implants for women and undersized implants for men. A high stage of femoral arthrosis can lead to the under and oversized planning of the surgeon. Since the surgeon's experience in planning did not show an effect on the adherence to templating, the beneficial effect of digital templating before surgery should be discussed.

The incidence of human immunodeficiency virus (HIV)-infected cases that need total joint replacement (TJR) is generally rising. On the other hand, modern management of HIV-infected cases has enabled them to achieve longevity while increasing the need for arthroplasty procedures due to the augmented dege-nerative joint disease and fragility fractures, and the risk of osteonecrosis. Although initial investigations on joint replacement in HIV-infected cases showed a high risk of complications, the recent ones reported acceptable outcomes. It is a matter of debate whether HIV-infected cases are at advanced risk for adverse TJR consequences; however, the weak immune profile has been associated with an increased probability of complications. Likewise, surgeons and physicians should be aware of the complication rate after TJR in HIV-infected cases and include an honest discussion of the probable unwelcoming complication with their patients contemplating TJR. Therefore, a fundamental review and understanding of the interaction of HIV and arthroplasty are critical.

Avascular necrosis of the femoral head typically occurs in the young population. Core decompression in the precollapse stage provides pain relief and preservation of the femoral head. The results of core decompression vary considerably despite the early diagnosis. Clinicians concur that primary treatment should focus on preserving the natural surface of the joint. This study investigated the predictive risk factors of failure in femoral head decompression.

We retrospectively reviewed 135 patients and 207 hips (77 male (127 hips) and 58 female (80 hips)) who underwent core decompression (mean age: 34.7 years [age range: 21-71]) from April 2010 to December 2017. All patients were followed by a mean of 57 months. All hips were in the precollapse stage (Ficat I, II).

A total of 207 hips were treated with core decompression surgery, and the overall success rate was 58%. The higher grade of Kerboul, Ficat, ARCO classifications, multifocal avascular necrosis of the femoral head, smoking, opium, and corticosteroids were significantly associated with a higher failure rate after core decompression in univariate analysis. In multivariate logistic regression analysis, the Kerboul and Ficat classifications, alcohol consumption, and multifocal avascular necrosis of the femoral head were significantly correlated with core decompression failure. The most common predictive factors in core decompression failure were Ficat II, Kerboul stage 3, multifocal avascular necrosis of the femoral head, and alcohol consumption.

In conclusion, we had an overall 58 % success rate in core decompression of femoral head avascular necrosis. Based on the results of this study, imaging evaluation and imaging-based classifications are the most valuable predictor factors for the success of core decompression. Consistent with previous reports, corticosteroid was not a significant predictor of core decompression failure.

Since femoral and horizontal offsets may be contributing factors to hip and pelvic balance, this study seeks to determine whether there is a correlation between pelvic obliquity (PO) after unilateral total hip arthroplasty (THA) and horizontal/vertical offset differences of the replaced and contralateral natural joints.

A cross-sectional study was performed on adult patients who underwent unilateral THA between 2017 and 2020. An expert orthopaedic resident measured PO angles and offset parameters. "Delta medial offset" is considered medial offset of the replaced hip minus the medial offset of the contralateral side. "Absolute delta medial offset" is considered the absolute value of the "Delta medial offset."

Finally, 133 patients were included in the study with a mean (SD) age of 45.3 ± 14.8 years and 57.9% female. The PO values (median, IQR) changed from 3.2 (1.7-5.7) before THA to 3.0 (1.50-5.6) after THA, not significantly decreased (P = 0.31). The PO after THA is significantly correlated with PO before THA (correlation coefficient of 0.457, P < 0.001), the delta medial offset after THA (correlation coefficient of - 0.24, P = 0.006), and the absolute delta medial offset after THA (correlation coefficient of 0.284, P = 0.001). The amount of changes of delta medial offset, before and after surgery, was not significantly correlated to PO or PO changes after surgery.

PO before the THA and medial offset discrepancy after THA are two important contributing factors for post-operative PO. Restoring the medial offset of the affected side and lowering the delta medial offset between the two sides can significantly decrease post-operative PO.

We aimed to determine symptomatic Coronavirus disease 2019 (COVID-19) rates within 1 month of elective arthroplasty for vaccinated individuals and to determine whether vaccination guarantees protection against COVID-19 after arthroplasty (primary outcome). In addition, the 90-day surgical complications were compared to those of an unvaccinated group (secondary outcome).

A prospective cohort study was conducted on elective joint arthroplasty patients at 3 tertiary hospitals in 2 major cities (Tehran and Isfahan) in our country (Iran). The outcomes of the COVID-19-vaccinated group were assessed between October 2021 and March 2022. Ninety-day surgical complications were compared with a historical cohort of unvaccinated patients treated earlier in the pandemic (April 2020-March 2021).

The study included 1717 consecutive patients: 962 vaccinated and 755 unvaccinated. In the vaccinated group, 38 patients (3.9%) contracted COVID-19, 4 (10.5%) were hospitalized again, and none required intensive care unit admission. The multivariate logistic regression analysis revealed that COVID-19-positive cases are more likely to be female (odds ratio [OR] = 12.5), to have visitors to their home (OR = 4.7), and to stay longer in the hospital (OR = 1.2) than COVID-19-negative cases. Compared to unvaccinated patients, the postoperative COVID-19 rate was not significantly different (3.9% vs 2.4%, P = .07). The incidence of surgical complications was similar between the 2 groups (P > .05).

The vaccination does not provide a guarantee that a patient will not contract COVID-19 following their arthroplasty surgery, especially in a region with a high rate of COVID-19. We believe reasonable perioperative COVID-19 precautions may be warranted even in vaccinated patients.

To determine the mid-term outcomes of conventional cementless Total Hip Arthroplasty (THA) in patients with avascular necrosis (AVN) of the femoral head and compare to patients with primary hip osteoarthritis (OA).

A total of 330 consecutive primary THA procedures (AVN and OA) performed between 2010 and 2013 by a single surgeon and in a single center using the direct anterior approach (DAA) were included. Assessments including SF-36, WOMAC, and Harris Hip Scores (HHS) were retrieved from patients before the surgery and at the latest follow-up. Clinical and functional outcomes were compared between the AVN and OA groups.

A total of 294 consecutive THA (AVN = 107, OA = 187) with 104.4 ± 6.2 months follow-up were analyzed, which AVN patients were significantly younger (32.0 vs. 59.6 y/o). Corticosteroid 34 (31.8%), idiopathic AVN 31 (29.0%) and use of unapproved weight gain supplements (UWGS) 23 (21.5%) were the main reasons for AVN. Despite that preoperative scores were comparable (P > 0.05), the HHS, SF-36, and WOMAC scores are significantly higher in the AVN group after THA surgery (P < 0.05). Moreover, flexion and abduction ROM were significantly higher in the AVN group (P < 0.05). Regarding each complication, no significant difference was observed between groups. In the whole sample, there were 5 (1.7%) revisions due to loosening of acetabular components, all the OA group (P > 0.05).

Conventional cementless THA with highly cross-linked polyethylene provides satisfactory mid-term results in patients with AVN with a low rate of postoperative complications. Compared to primary OA patients, this group reaches superior postoperative scores.

In total hip replacement (THR), fretting and corrosion at the modular head-neck junction (trunnionosis) may cause adverse local tissue reaction (ALTR). In this report, we presented a 34 years woman with a history of THR eight years ago, presenting with acute pain and limping. The radiographic assessment revealed stem-head dislocation for which a revision hip surgery was planned. Surprisingly, we observed pseudotumor and tissue necrosis resulting from the body's reaction to cobalt-chromium alloy. The revision surgery entailed pseudotumor debridement and replacing the femoral head with a new metal head (size 36, long). Due to the separation of the femoral head on a stem, we fixed it on a stem using bone cement. The stem (Omnifit®, Stryker®) was well-fixed and retained to avoid fractures and infection risk. This technique revealed an acceptable outcome without recurrence of ALTR after a one-year follow-up. Our findings suggest that stem dislocation secondary to trunnionosis might be a long-term complication after THR with subsequent ALTR.

Investigation of the crossover sign (COS) in different degrees of tilt in pelvises made by three-dimensional printing of CT scans among patients with normal hip versions was carried out.

Radiology CT scans of 8 normal pelvises reconstructed in 3D and the effect of sequential tilting on the presence of the false-positive COS in 48 radiographs were investigated.

The COS was seen in 77% of the AP radiographs during tilt changes. The average distance between the tip of the coccyx and the symphysis pubis was 32.06 ± 10.99 mm. Also, COSs were present in all radiographs from 6 degrees tilt and above.

Minor tilting of the pelvis can result in a false-positive crossover sign on AP plain radiographs.