Cup Placement Research Articles

Evaluation of three acetabular measurement methods for total hip replacement in dogs.

To compare three measurement methods for acetabular sizing and evaluate the influence of osteoarthritis (OA) on the accuracy of measurements. Observational study. Radiographic images of 73 hip joints from 60 dogs with cementless cups. Radiographs were anonymized and measured independently by three observers. One observer measured 12 sets of radiographs three times. A best-fit acetabular circle (AC) and cranial-caudal acetabular line (AL) were measured on ventral-dorsal (VD) radiographic view and open leg lateral (OLL) view. A best-fit femoral head circle (FHC) was measured on VD, OLL, and craniocaudal horizontal beam (CCHB) views. Two observers scored the OA in each hip joint. Intra- and interobserver consistency and repeatability and bias relative to implanted cup size were calculated and analyzed. Intraobserver consistency and repeatability were excellent for all measurements. Interobserver consistency was excellent (ICC > 0.9) for ACVD and ACOLL and was good (0.75 < ICC ≤ 0.9) for all other methods. Bias was small for AC and AL measurements (range, -0.46 to 0.45 mm) and large for FHC measurements (-3.58 to -2.42 mm). OA score significantly influenced bias for all acetabular measurement methods (p < 0.05). All acetabular measurement methods were highly consistent within an observer. Interobserver consistency was highest for ACVD and ACOLL. FHC measurements underestimated cup size. Higher OA scores decreased the accuracy of all acetabular measurement methods. Superimposing a circle on the acetabulum seen on VD radiographic view accurately measures the acetabulum before cementless cup placement.

Comparison of Implant Placement Accuracy Between Manual, Robot-Assisted, Computer-Navigated, Augmented Reality Navigated, Patient-Specific Instrumentation, and Accelerometer Navigated Total Hip Arthroplasty: A Systematic Review and Network Meta-Analysis.

Malpositioning of the acetabular cup during total hip arthroplasty (THA) can lead to complications. Robotic surgery and navigation techniques aim to address this issue, but there is limited evidence regarding which method can achieve better clinical outcomes. Therefore, this network meta-analysis (NMA) aimed to compare the efficacy of various navigation methods. This NMA of prospective randomized controlled trials compared robot-assisted systems (RAS), computer-assisted navigation systems (CAS), augmented reality-based portable navigation (AR), patient-specific instrumentation (PSI), portable accelerometer-based navigation (PN), and conventional methods (C) for THA procedures. We searched MEDLINE, EMBASE, Cochrane, Central Register of Controlled Trials, International Clinical Trials Platform Search Portal, and ClinicalTrials.gov. databases. The primary outcomes included revision surgery and postoperative clinical scores, and the secondary outcomes encompassed cup placement accuracy, acetabular cup placement outliers from the Lewinnek safe zone, surgical time, and complications. We used a Bayesian random-effects NMA, and confidence of evidence was assessed using confidence in NMA. We identified 45 studies including 2,122 patients. We did not find large differences in revision surgery, clinical outcome scores, cup inclination, or anteversion angle accuracy among the modalities. AR, CAS, and PSI exhibited a lower risk of outliers from safe zones than C. In addition, RAS and CAS had a longer surgical time than C. Robotic and navigation tools did not reduce the revision risk or enhance clinical outcomes. AR, CAS, PSI, and PN may decrease the risk of cup placement outliers in safe zones. However, the cup placement accuracy was equivalent, and the surgical time may be longer in RAS and CAS than in C. Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

An Exploratory Study: Controversial Beliefs and Practices of Hijama Practitioners of Karachi, Pakistan

Background: Cultural and spiritual beliefs have preserved the use of traditional practices, including al hijama (wet cupping), which is widely recognized for its purported therapeutic value and historical significance. Despite its popularity, the practice often lacks formal training and is frequently administered by unqualified practitioners, leading to false beliefs and potentially unsafe practices. Objective: To investigate the scientific knowledge and beliefs of hijama practitioners of Karachi, Pakistan, with a focus on identifying misconceptions, variations in practice, and the influence of cultural and religious beliefs on the practice of hijama therapy. Methodology: A cross-sectional exploratory study was conducted involving 114 hijama practitioners from Karachi, who were recruited through various WhatsApp groups and enrolled in a seminar held in January 2023. The participants were required to complete a 37-item questionnaire covering their qualifications, practice methods, hygiene standards, and beliefs about the hijama therapy. Data were analyzed using spss version 20, employing mean, standard deviation, chi-square tests, and frequency distribution. Results: Most participants (97.4%) were female, with only 39.5% possessing a license to practice. Many practitioners (89.5%) were motivated by the religious significance of hijama. The knowledge regarding the scientific theories and mechanism of action of hijama therapy was known by 56.4%. Practices varied widely regarding hygiene, blade type, and cup placement. 38.1% did not consistently check for infectious diseases. Additionally, the practice of reciting Qur’anic verses was widespread, believed to enhance the therapy's effectiveness which shows strong religious connotation. Conclusion: The study reveals a substantial gap in formal training among hijama practitioners, leading to variations in practice and potential safety concerns. There is a pressing need for standardized training and regulations to ensure the safe and effective practice of hijama therapy. Further research is essential to establish evidence-based guidelines which improve the public and physician awareness towards this therapy’s risks and benefits.

Early Hip Dislocation Rate in a Consecutive Series of 1093 Primary Total Hip Arthroplasties Using Imageless Navigation

Purpose: Postoperative hip dislocation remains a major complication in total hip arthroplasty. Various studies have demonstrated that several factors influence dislocation. While computer-assisted navigation has been proposed to enhance component alignment, its impact on dislocation rates remains unclear. This study aimed to investigate the early dislocation incidence and associated risk factors in primary total hip arthroplasty (THA) using imageless navigation. Methods: A retrospective review of patients undergoing imageless-navigated THA between February 2013 and December 2022 was conducted. Inclusion criteria comprised primary THA with a minimum 6-month follow-up. Statistical analysis included univariate regression to identify dislocation risk factors. Results: A total of 1093 THAs were analyzed. Dislocation occurred in 16 cases (1.5%), six in elective procedures (0.76%), and 10 in femoral neck fracture (FNF) (3.28%). The univariate regression analysis revealed that FNF emerged as a significant risk factor (OR = 4.418, P = 0.004), while age, gender, femoral head size, and save zone cup placement of Lewinnek did not significantly affect dislocation rates. Conclusions: Navigation use showed a reduced rate of early dislocation. FNF is a factor associated with postoperative hip dislocation in primary THA.

Clinical and Radiographic Outcomes With Minimum 2-Year Follow-up and Sub-Analysis of Navigation vs Non-Navigation for Hip Resurfacing.

The purpose of this study was to report the short-term clinical outcomes of hip resurfacing with navigation and the impact on accuracy of acetabular implant placement in both the frontal and sagittal planes. Data were retrospectively analyzed for patients who received hip resurfacing between 2010 and 2021. Eligible patients had postoperative radiographs and completed a minimum 2-year follow-up questionnaire for the following patient-reported outcomes: modified Harris Hip Score (mHHS), Harris Hip Score (HHS), Forgotten Joint Score (FJS), visual analog scale (VAS) score, satisfaction, and Hip Disability and Osteoarthritis Outcome Score, Joint Replacement (HOOS-JR). Hips were propensity matched in a 1:1 ratio based on the use of navigation, age, and body mass index. The percentage of hips that met the minimal clinically important difference (MCID) for mHHS and VAS score was noted. Component placement analysis was conducted based on the safe zones defined by Lewinnek and Callanan and the Relative Acetabular Inclination Limit. Seventy-six hips were matched, 38 per group. No differences were observed in patient-reported outcomes or the percentage of hips reaching MCID between the groups. The navigation group was 28.8 and 6.8 times more likely to be within the Callanan and Lewinnek safe zones, respectively. Based on the Relative Acetabular Inclination Limit, the navigation group was 3.1 and 6.4 times more likely to be within the 95% and 99% CI safe zones, respectively. Comparable improvements in patient-reported outcomes were observed in the two groups during a minimum 2-year follow-up. Navigation-assisted surgery enhances the accuracy of acetabular component positioning, with a higher likelihood of cup placement within the safe zones. [Orthopedics. 202x;4x(x):xx-xx.].

Accuracy of Cup Placement Angle, Leg Lengthening, and Offset Measurement Using an AR-Based Portable Navigation System: Validation in Supine and Lateral Decubitus Positions for Total Hip Arthroplasty

Background and Objectives: Total hip arthroplasty (THA) requires accurate implant placement to ensure optimal outcomes. In this study, the AR Hip navigation system, an imageless portable navigation tool using augmented reality (AR), was evaluated for measuring radiographic inclination (RI), anteversion (RA), leg lengthening (LL), and offset (OS) changes in supine and lateral decubitus THA. Notably, this is the first report to assess the accuracy of LL and OS measurements using AR technology. Methods: We analyzed 48 hips from primary THA patients: 17 in the supine (S) group and 31 in the lateral (L) group. RI, RA, LL, and OS were measured intraoperatively using AR Hip and postoperatively using Zed Hip 3D software (Version 18.0.0.0). The absolute errors and outlier rates (≥5° for RI/RA and ≥5 mm for LL/OS) were compared between groups. Results: The mean intraoperative RI values with AR Hip were 40.1 ± 0.6° (S), 40.2 ± 1.2° (L), and 40.1 ± 1.0° (total), while the postoperative RI values with Zed Hip were 39.7 ± 2.9° (S), 39.5 ± 2.5° (L), and 39.6 ± 2.6° (total). The absolute errors were 1.8 ± 1.7° (total), with no significant group differences (p = 0.957). For RA, the errors were 2.0 ± 1.2° (total) (p = 0.771). The LL errors were 2.3 ± 2.2 mm (total) (p = 0.271), and the OS errors were 3.5 ± 2.8 mm (total) (p = 0.620). The outlier rates for RI were 11.8% (S) and 3.2% (L); for RA, 0% (S) and 3.2% (L); for LL, 29.4% (S) and 6.5% (L) with a significant difference (p = 0.031); and for OS, 23.5% (S) and 25.8% (L). No significant differences were observed for RI, RA, or OS. Conclusions: AR Hip provided accurate measurements of cup orientation, LL, and OS in both supine and lateral THA. Importantly, this study is the first to report the accuracy of LL and OS measurements using AR technology, demonstrating the potential of AR Hip for improving THA precision.

Accuracy of robotic arm-assisted versus computed tomography-based navigation in total hip arthroplasty using the direct anterior approach: a retrospective study

BackgroundA robotic arm-assisted and a computed tomography (CT)- based navigation system have been reported to improve the accuracy of component positioning in total hip arthroplasty (THA). However, no study has compared robotic arm-assisted THA (rTHA) to CT-based navigated THA (nTHA) concerning accuracy of cup placement and acetabular fractures using the direct anterior approach (DAA). This study aimed to compare the accuracy of cup placement and the presence of intraoperative acetabular fractures between rTHA and nTHA using DAA in the supine position.MethodsWe retrospectively investigated 209 hips of 188 patients who underwent rTHA or nTHA using DAA (rTHA using the Mako system: 85 hips of 79 patients; nTHA: 124 hips of 109 patients). After propensity score matching for age and sex, each group consisted of 73 hips. We evaluated clinical and radiographic outcomes, comparing postoperative cup orientation and position, measured using a three-dimensional templating software, to preoperative CT planning. Additionally, we investigated the prevalence of occult acetabular fracture.ResultsClinical outcomes were not significantly different between the groups at 1 year postoperatively. The mean absolute error of cup orientation was significantly smaller in the rTHA group than in nTHA (inclination: 1.4° ± 1.2° vs. 2.7° ± 2.2°, respectively; p = 0.0001, anteversion: 1.5° ± 1.3° vs. 2.2° ± 1.7°, respectively; p = 0.007). The cases within an absolute error of 5 degrees in both RI and RA were significantly higher in the rTHA (97.3%) than in nTHA group (82.2%) (p = 0.003). The absolute error of the cup position was not significantly different between the two groups. The prevalence of occult acetabular fracture did not differ significantly between the two groups (rTHA: n = 0 [0%] vs. nTHA: n = 1 [1.4%]).ConclusionCup placement using DAA in the supine position in rTHA was more accurate with fewer outliers compared to nTHA. Therefore, rTHA performed via DAA in a supine position would be useful for accurate cup placement.

Accelerometer-based portable navigation system shows no superior accuracy over pelvic alignment guide for acetabular cup placement in total hip arthroplasty in lateral decubitus position.

Total hip arthroplasty (THA) using a portable navigation system (PNS) incurs costs per procedure. However, it does not require a large console. This study aimed to compare the accuracy of acetabular cup placement using a pelvic alignment guide (PAG) attached to the pelvis and an accelerometer-based PNS in THA performed in the lateral decubitus position. We retrospectively analyzed 100 hips that underwent primary THA in the lateral decubitus position between July 2018 and January 2021. The PAG was used in 50 hips, whereas the PNS was used in the other 50. Cup placement accuracy was measured using postoperative computed tomography scans, comparing errors in inclination and anteversion angles. The surgical time, blood loss, and complications were recorded. The follow-up period was at least 2 years in all cases. The mean absolute error of the inclination angle was similar between the groups (the PAG group: 3.7° ± 2.3° [range, 0.0-9.0]; the PNS group: 3.7° ± 2.3° [range, 0.2-10.5], p = 0.705). The mean absolute error of the anteversion angle was significantly smaller in the PAG group than in the PNS group (3.0° ± 2.4° [range, 0.0-9.7] vs. 6.5° ± 4.8° [range, 0.3-17.3], p < 0.001). The PAG group had a higher proportion of hips within 5° and 10° of the target angle (64 vs. 42%, P = 0.028, and 100 vs. 74%, p < 0.001, respectively). The PNS group had six hips with anteversion errors of 15° or more. Surgical time and blood loss were lower in the PAG group. The PNS group had one dislocation, whereas the PAG group did not. The accelerometer-based PNS did not demonstrate superior cup alignment accuracy compared to the PAG in THA performed in the lateral decubitus position. This finding informs surgeons that computer-assisted surgery is not necessarily superior to conventional THA using a PAG.

Precision of Cup Positioning Using a Novel Computed Tomography Based Navigation System in Total Hip Arthroplasty

Background and Objectives: Navigation systems are designed to enhance surgical precision, improving patient outcomes and reducing the risk of implant misplacement. In this study, we have evaluated a novel orthopedic surgical platform that utilizes CT imaging with AI-based algorithms to automate several critical aspects of total hip arthroplasty. It contains three modules—preoperative planning, navigation during surgery, and follow-up analysis. The primary objective of the current study was to evaluate the precision of the navigation tool in cup placement, i.e., whether the information displayed for navigation correctly reflected the actual position of the implant. Materials and Methods: Surgery outcomes of 15 inter-rater measurements on human cadavers and 18 surgeries on patients who underwent total hip replacement using the navigation tool were analyzed. Results: In the inter-rater assessment, the mean errors were −0.31 ± 1.42° for anteversion, 1.06 ± 1.73° for inclination, and −0.94 ± 1.76 mm for cup position depth. In patients’ surgeries, the mean errors were −0.07 ± 2.72° for anteversion, −0.2 ± 0.86° for inclination, and 0.28 ± 0.78 mm for cup depth. Conclusions: The navigation tool offers intra-operative guidance on notable precision in cup placement, thereby effectively mitigating the risk of cup malpositioning outside the patient-specific safe zone.

Assessment of Cup Placement Impact on Functional Outcomes in Total Hip Replacement: A Retrospective Analysis of 20 Patients

Introduction:Total hip replacement surgery is gaining popularity as a treatment for hip disorders, replacing alternative treatments like excisional arthroplasty, osteotomy, arthrodesis, and hemiarthroplasty. This research aims to evaluate the effect of the acetabular cup on functional outcomes, particularly in younger patients with hip arthritis and femur neck fractures.Materials And Methods:This study aimed to evaluate the placement of the acetabular cup and its association with functional outcomes in total hip replacement (THR). 20 patients were randomly selected from the MRD department and underwent pelvic CT scans postoperatively. Functional results have been analyzed using the Harris Hip Score. The acceptable cup version range was 15 ± 10 degrees, and patients outside this range were closely examined for rotational movements. Results: A study of 20 patients with a neck or femur fracture found that 11 patients had a right knee injury, while 9 had a left knee injury. After a year postoperatively, 18 patients reported no pain, while 2 had mild pain. Functional assessment depicted better outcomes in 17 patients, good outcomes in 2 patients, and fair outcomes in 1 patient. Radiological analysis revealed a mean cup version of 17.77 degrees, with complications including one dislocation and three limb length discrepancies. None of the patients developed an infection.Conclusion:The study found that 90% of patients had excellent functional outcomes, with only 10% exhibiting excessive anteversion. CT scan-based measurements of cup placement provided reliable predictions, consistent with intraoperative assessment of cup positioning.

The effect of intraoperative fluoroscopy on acetabular component positioning and patient anatomy restoration during total hip arthroplasty: A systematic review and meta-analysis.

In total hip arthroplasty (THA), the positioning of components holds critical importance for factors such as joint stability, polyethylene liner wear, and range of motion. This meta-analysis aimed to compare the effects of intraoperative fluoroscopy (IF) versus no use of IF on component positioning and the restoration of patient anatomy during THA. We conducted our systematic review following the recommendations outlined in the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guideline. The literature search was performed from the inception of medical databases up to August 2023. PubMed, Embase, Web of Science, Cochrane Controlled Trials Register, Cochrane Library, Highwire, Wanfang, China National Knowledge Infrastructure (CNKI), China Biology Medicine Disc (CBM), and China Science and Technology Journal (CSTD) databases were systematically searched to identify relevant studies comparing IF versus no IF during primary THA. Thirteen studies involving 2195 patients (2207 hips) were incorporated in the Analysis. No statistically significant differences were observed between the groups in terms of acetabular cup inclination angle (ACIA, P = .9), ACIA within the safe zone rate (P = .87), acetabular cup anteversion angle (ACAA, P = .42), ACAA within the safe zone rate (P = .35), combined safe zone rate (P = .30), limb length difference (LLD, P = .13), dislocation rate (P = .76), and infection rate (P = .97). In comparison to the no fluoroscopy group, the IF group exhibited prolonged operation time (P < .00001) and reduced femoral component offset difference (FCOD, P = .03). IF did not demonstrate improvements in acetabular cup placement, limb length difference, or dislocation occurrence. Nonetheless, IF showed a significant enhancement in restoring femoral offset. It is noteworthy that surgeons operating in facilities with lower patient volumes may observe more pronounced benefits from IF.

Change of Sacral Slope according to the Surgical Position in Total Hip Arthroplasty.

Pelvis tilting in sagittal plane influences the acetabular cup position. Majority of total hip arthroplasty (THA) are performed in lateral decubitus surgical position. This study is to assess whether there is any difference in sacral slope between standing and lateral decubitus position and influence of this variation in planning acetabular cup anteversion. This is a prospective study including 50 patients operated between January 2020 to March 2022. Preoperative radiograph included lumbosacral spine lateral X-ray in standing, supine and lateral decubitus positions to calculate the sacral slope for assessment of anterior or posterior pelvic tilting. In our study, we determined the position of the acetabular cup based on changes in sacral slope between standing and lateral decubitus postures. For patients whose sacral slope increased from lateral decubitus to standing, we implanted the acetabular component with a higher degree of anteversion. Conversely, for patients with reverse phenomenon, the cup was inserted at lower anteversion. Twenty-four patients (48.0%) had increase in sacral slope from lateral decubitus to standing whereas 26 patients (52.0%) had decrease in sacral slope. There was linear correlation between difference in preoperative sacral slope and postoperative cross table lateral cup anteversion. Harris hip scores improved from 40.78 to 85.43. There was no subluxation or dislocation in any patient at minimum 2-year follow-up. Individualized acetabular cup placement is important for better functional outcome in THA. Evaluation of pelvic tilting in lateral decubitus position is necessary for better positioning of acetabular cup and avoid postoperative complications.

Does Preoperative Virtual Reality Experience Enhance Implant Positioning Accuracy in Total Hip Arthroplasty?

Purpose Total hip arthroplasty (THA) requires precise implant positioning to ensure long-term success. Herein, we evaluated the effect of virtual reality (VR) on the surgical precision of THA, particularly when used by experienced surgeons. Methods In this single-center, prospective, case-control study, 34 patients who underwent primary THA performed by a single experienced surgeon were divided into the control (without VR simulation) and VR (with VR simulation) groups. Preoperative planning involved the creation of three-dimensional models from computed tomography scans using ZedHip® software (Lexi, Tokyo, Japan). The primary outcomes assessed included the accuracy of implant placement, operative time, and intraoperative blood loss. The secondary outcomes included postoperative hospital stay and in-hospital complications. Results A significant improvement in radiographic inclination (RI) was observed in the VR group as compared to controls. Other surgical parameters, such as radiographic anteversion, operation time, blood loss, and postoperative hospital stay, showed no significant differences between the groups. Discrepancies in planned versus actual implant sizes were notedbut were not significantly different between groups. Conclusion VR application in preoperative planning improved the RI accuracy in acetabular cup placement for THA, demonstrating its potential to enhance surgical precision for experienced surgeons. This study highlights the evolving role of VR, from a training tool to an integral part of advanced surgical planning in orthopedics.

Dual Mobility Trapeziometacarpal Joint Arthroplasty: A Survey on Variations in Surgical Techniques and Patient Management.

Background: Dual mobility total joint arthroplasty is gaining popularity for trapeziometacarpal joint (TMCJ) arthritis, with evolving indications, surgical technique and rehabilitation. The aim of this study was to obtain detailed insight into the variations in indications, surgical technique and rehabilitation for TMCJ arthroplasty with dual mobility implants, across a large international cohort of surgeons. The secondary aim was to analyse if there were differences in TMCJ arthroplasty between highly and less experienced surgeons. Methods: An anonymised online survey was developed and distributed to the international hand surgery community of surgeons performing TMCJ arthroplasty. Responses were summarised, and a sub-analysis comparing indications, contra-indications, surgical technique, implant placement, rehabilitation and complications between highly and less experienced surgeons was performed. Results: Of the 203 included respondents, 59 were considered highly experienced. Most respondents perform TMCJ arthroplasty under regional anaesthesia (84%), via a dorsolateral approach (78%) and with image-guidance for cup placement (84%). However, there is considerable variation in handling of scaphotrapeziotrapezoidal (STT) arthritis, cup positioning landmarks, postoperative immobilisation, first extensor compartment release and revision techniques. Highly experienced surgeons performed TMCJ arthroplasty for a larger proportion of their patients undergoing surgery for TMCJ arthritis, and a trapezium smaller than 8 mm or STT-OA was less frequently considered a contra-indication. Highly experienced surgeons preferred freehand osteotomy of the metacarpal and allowed office workers to return to work earlier. Conclusions: This survey shows that there is considerable variation in (contra)indications, surgical technique and rehabilitation amongst surgeons performing TMCJ arthroplasty, but only a few differences between highly and less experienced surgeons were identified. This data provides a reference for surgeons who want to familiarise themselves with increasingly popular procedure and may help surgeons already performing TMCJ arthroplasty to identify potential topics for future research to optimise its outcome. Level of Evidence: Level V (Therapeutic).

Dynamic change of acetabular component position in total hip arthroplasty based on the spinopelvic classification: a prospective radiographic study

PurposeRecent studies have proposed optimizing the position of the acetabular component based on spinal deformity and stiffness classification to avoid mechanical complication after total hip arthroplasty (THA). The aim of this study was to characterize the dynamic changes in cup alignment post-THA based on the spinopelvic classification and to evaluate the efficacy of cup placement of preventing dislocation.MethodsThis prospective study included a total of 169 consecutive patients awaiting THA who were classified into four groups based on spinal deformity (pelvic incidence minus lumbar lordosis) and spinal stiffness (change in sacral slope from the standing to seated positions). The cups were aligned based on the group with fluoroscopy. Additionally, postoperative radiographic inclination (RI), radiographic anteversion (RA) in standard anteroposterior radiograph, and lateral anteinclination (AI) in sitting and standing positions were measured. The cumulative incidence of dislocation was evaluated at a follow-up two years post-THA.ResultRA was significantly greater in the group with normal spine alignment and stiff spine than in other groups (P = 0.0006), and AI in the sitting position was lower than in other groups (P = 0.012). Standing AI did not significantly differ between the groups. One posterior dislocation occurred during the study period (0.6%).ConclusionAI in the sitting position was lower in patients with normal spinal alignment and stiff spine despite larger RA in the standard anteroposterior radiographs. Consequently, with more anteversion in the normal spinal alignment and stiff spine group, spinopelvic parameters can help guide cup placement to prevent short-term dislocation post-THA.

VIRTUAL IMPINGEMENT TESTS IN 113 PATIENTS UNDERGOING TOTAL HIP ARTHROPLASTY

Hip precautions following total hip arthroplasty (THA) limits flexion, adduction and internal rotation, yet these precautions cause unnecessary psychological stress. This study aims to assess bony and implant impingement using virtual models from actual patient's bony morphology and spinopelvic parameters to deduce whether hip precautions are necessary with precise implant positioning in the Asian population.Individualized sitting and standing sacral slope data of robotic THAs performed at two tertiary referral centers in Hong Kong was inputted into the simulation system based on patients’ pre-operative sitting and standing lumbar spine X-rays. Three-dimensional dynamic models were reconstructed using the Stryker Mako THA 4.0 software to assess bony and implant impingement both anteriorly and posteriorly, with default cup placement at 40° inclination and 20° anteversion. Femoral anteversion followed individual patient's native version. A 36mm hip ball was chosen for all cups equal or above 48mm and 32mm for those below. Anterior impingement was assessed by hip flexion and posterior impingement was assessed by hip extension.113 patients were included. At neutral rotation and adduction, no patients had anterior implant impingement at hip flexion of 100°. 1.7% had impingement at 110°, 3.5% had impingement at 120°, 9.7% had impingement at 130°. With 20° of internal rotation and adduction, 0.8% had anterior implant impingement at hip flexion of 90°, 7.1% had impingement at 100° and 18.5% had impingement at 110°. With the hip externally rotated by 20°, 0.8% of patients had posterior implant impingement, and 8.8% bony impingement at 0° extension.With enabling technology allowing accurate component positioning, hip precautions without limiting forward flexion in neutral position is safe given precise implant positioning and adequate osteophyte removal. Patients should only be cautioned about combined internal rotation, adduction with flexion.

SHORTENING OSTEOTOMIES OF THE FEMUR DURING TOTAL HIP ARTHROPLASTY FOR DEVELOPMENTAL HIP DYSPLASIA

Total hip arthroplasty (THA) for congenital hip dysplasia (CDH) presents a challenge. In high-grade CDH, key surgical targets include cup placement in the anatomical position and leg length equality. Lengthening of more than 4 cm is associated with sciatic nerve injury, therefore shortening osteotomies are necessary. We present our experience of different shortening osteotomies including advantages and disadvantages of each technique.89 hips, in 61 pts (28 bilateral cases), for high CDH were performed by a single surgeon from 1997 to 2022. 67 patients were female and 22 were male. Age ranged from 38 to 68 yrs. In all patients 5–8cm of leg length discrepancy (LLD) was present, requiring shortening femoral osteotomy. 12 patients underwent sequential proximal femoral resection with trochanteric osteotomy, 46 subtrochanteric, 6 midshaft, and 25 distal femoral osteotomies with simultaneous valgus correction were performed. All acetabular prostheses were placed in the true anatomical position. We used uncemented high porosity cups. Patients were followed up for a minimum of 12 months.All osteotomies healed uneventfully except 3 non-unions of the greater trochanter in the proximal femur resection group. No femoral shaft fractures in proximally based osteotomies. No significant LLD compared to the unaffected or reconstructed side. 2 patients suffered 3 and 5 degrees malrotation of the femur in the oblique sub-trochanteric group. 3 patients suffered transient sciatic nerve palsies.Shortening femoral osteotomies in the treatment of DDH are necessary to avoid injury to the sciatic nerve. In our series, we found transverse subtrochanteric osteotomies to be the most technically efficient, versatile and predictable in their clinical outcome, due to the ability to correct rotation and preserve the metaphyseal bone integrity, allowing for better initial stem stability. Distal femoral osteotomies allowed for controllable correction of valgus knee deformity.

Polyethylene liner dissociation in total hip arthroplasty: a retrospective case–control study on a single implant design

BackgroundModular acetabular components for total hip arthroplasty (THA) provide intraoperative flexibility; however, polyethylene liner dissociation may occur. This study aimed to examine the incidence and causes of liner dissociation associated with a specific acetabular component design at a single centre.Materials and methodsA retrospective analysis of 7027 patients who underwent primary THA was performed to identify isolated liner dislocations. Patient demographics, clinical presentations, surgical and implant details, and both radiographic and computed tomography (CT) findings were analysed. Patients with liner dislocation were matched to a control group via 2:1 propensity score matching, and a logistic regression analysis was employed to identify associated risk factors.ResultsA total of 32 patients (0.45%) experienced liner dislocation at a mean 71.47 ± 60.10 months post surgery. Significant factors contributing to dislocations included the use of a conventional compared with a highly crosslinked polyethylene component (p = 0.049) and screw fixation (p = 0.028). Radiographic and CT analysis highlighted the importance of proper component orientation, revealing that patients experiencing dislocations demonstrated significantly lower acetabular cup anteversion angles (p = 0.001) compared with the control group. Impingement and malposition, identified in 41% and 47% of the cases, respectively, further underscored the multifactorial nature of dislocation risks.ConclusionsWhile the overall rate of polyethylene liner dislocation was low, the findings of this study highlight the importance of appropriate cup placement to decrease the risk of dissociation. It further substantiates the influence of impingement and malposition in liner displacement, with increased mechanical stress exerted on the locking mechanism under adverse conditions and the potential risk increase due to screw placement.

Adverse events associated with robotic-assistance in total hip arthroplasty: an analysis based on the FDA MAUDE database.

The Food and Drug Administration (FDA) maintains the Manufacturer and User Facility Device Experience (MAUDE) database for reporting adverse events associated with medical devices, including emerging technologies, such as robotic-assisted total hip arthroplasty (THA). Aim of this study was to evaluate the variation of adverse events associated with robotics in THA. Medical device reports (MDRs) within the MAUDE database were identified between 2017 and 2021. For MDR identification the product class "orthopaedic stereotaxic equipment" and terms associated with THA were used. Individual adverse events were identified and organised by type and consequences, such as patient injury, surgical delay, or conversion to the manual technique. 521 MDRs constituting 546 discrete events were found. The most common reported complication was intraoperative hardware failure (304/546, 55.7%), among which the most common failure was a broken impaction handle/platform (110, 20.1%). Inaccurate cup placement was the second most common reported complication (63, 11.5%). Abandoning the robot occurred in 13.0% (71/521) of reports. A surgical delay was noted in 28% (146/521) of reports, with an average delay of 17.9 (range 1-60) minutes. Identifying complications that may occur with robotics in THA is an important first step in preventing adverse events and surgical delays. Database analysis provide an overview of the range of complications.

In silico analysis of the patient-specific acetabular cup anteversion safe zone

IntroductionVarious computer-assisted surgical systems claim to improve the accuracy of cup placement in total hip arthroplasties after assessing spinopelvic mobility to prevent prosthetic impingement. However, no study has yet analyzed the extent of the patient-specific cup anteversion safe zones. HypothesisWe hypothesized that most patients have a safe zone >10 °, except those with abnormal spinopelvic mobility, who have a much narrower safe zone. Materials and methodsWe simulated the risks of prosthetic impingement using the planned cup anteversion. The consecutive cohort included 341 patients who underwent total hip arthroplasty. Our primary endpoint was the patient-specific impingement-free zone for cup anteversion, which was then divided into four subgroups: 0 °, 1 ° to 5 °, 6 ° to 10 °, and >10 °. This data was then secondarily analyzed for abnormal spinopelvic mobility (the difference in the spinopelvic tilt [ΔSPT] from a standing to a flexed seated position >20 °). ResultsThe mean anteversion safe zone was 22.8 ° with 82.4% (281/341) of patients with a zone strictly >10 °. The mean safe zone was 8.9 ° (+/− 9 °) in patients with an ΔSPT ≥20 ° (18.2%), with 37.1% of these patients having a zone of 0 °, 16.13% a zone between 1 ° and 5 °, 8.06% a zone between 6 ° and 10 ° and 38.71% a zone >10 °. The mean safe zone was 25.9 ° (+/− 9 °) in patients with an ΔSPT <20 ° (81.8%), and the proportion of cases in each zone was 2.51%, 1.08%, 4.3%, and 92.11%, respectively (p < 0.001). ConclusionThe safe zone for anteversion appears to be fairly wide in most patients. However, identifying patients at risk of abnormal spinopelvic mobility seems necessary to identify the two-thirds of patients with a narrow safe zone. Level of evidenceIV; retrospective study