Cup In Total Hip Arthroplasty Research Articles

Does Pelvic Orientation Influence Wear Measurement of the Acetabular Cup in Total Hip Arthroplasty—An Experimental Study

Roentgen stereophotogrammetric analysis (RSA) is the gold standard to detect in vivo material wear of the bearing couples in hip arthroplasty. Some surgical planning tools offer the opportunity to detect wear by using standard a.p. radiographs (2Dwear), whilst RSA (3Dwear) needs a special radiological setup. The aims of this study are to prove the interchangeable applicability of a 2Dwear approach next to RSA and to assess the influence of different pelvic positions on measurement outcomes. An implant-bone model was used to mimic three different wear scenarios in seven pelvic-femur alignment positions. RSA and a.p. radiographs of the reference and a follow-up (simulated wear) pose were acquired. Accuracy and precision were worse for the 2Dwear approach (0.206 mm; 0.159 mm) in comparison to the 3Dwear approach (0.043 mm; 0.017 mm). Changing the pelvic position significantly influenced the 2Dwear results (4 of 7, p < 0.05), whilst 3Dwear results showed almost no change. The 3Dwear is superior to the 2Dwear approach, as it is less susceptible to changes in pelvic position. However, the results suggest that a 2Dwear approach may be an alternative method if the wear present is in the range of 100–500 µm and a.p. radiographs are available with the pelvis projected in a neutral position.

Early Complications of using Dual Mobility Cup in Total Hip Arthroplasty. A Systematic Review

Abstract Background Total hip arthroplasty (THA) is considered one of the most successful surgical procedures providing pain relief and improvement of function in patients with end-stage hip arthritis that does not respond to non-operative treatments. As health care continues to improve and life expectancy increases, the demand for total joint replacement will grow to reflect this more active, aging population. Objectives This study aims to review early complications of dual mobility cup arthroplasty. The objective is to perform a systematic review of early complications of dual mobility cup arthroplasty for primary and revision cases. Methodology Types of studies we will include randomized control trails (RCTs), controlled clinical trials, retrospective cohort studies, and we will exclude case reports, case series studies, cross sectional studies, non English studies. Search results will be conducted to systematic review management software and manually screened for eligibility to be included. PRISMA flowchart will be produced based on the search results and the inclusion/exclusion criteria. We will search the MED-LINE database, PubMed, Cochrane Bone and Muscle Trauma Group Specialized Register, Cochrane Register of Controlled Trails (The Cochrane Library) using the following keywords related to: THA, Dual mobility cup, complications, intraprosethetic dislocation. Results Early complication rate in dual mobility cups is significantly higher in revision cases compared to primary cases, with the exception of IPD which was significantly lower in revision cases. Early complication rate of conventional THA was significantly higher than both primary and revision dual mobility cups. Conclusion Dual mobility THAs are a good alternative to traditional bearing surfaces with long survivorship and low rates of instability after primary and revision THA. The rate of complications which are unique to the procedure, including intraprosthetic dislocation, is relatively low and limited mainly to earlier designs. High-quality, prospective, comparative studies are needed to further evaluate the use of dual mobility in primary and revision THA.

Functional outcome after dual mobility cups total hip replacement versus bipolar hemiarthroplasty in femoral neck fractures in active elderly patients: a randomized controlled trial

Background: Bipolar hemiarthroplasty (BA) has long been the preferred treatment and is performed in most patients with femoral neck fracture (FNF). The dual mobility cup total hip arthroplasty (DMTHA) has emerged as a relevant alternative to BA. Since then there is an on-going debate on the best implant to use. Age, comorbidities, patient independence, and potential surgical complications must be considered when choosing implants. The risk of dislocation is a crucial factor because of its important consequences. The authors evaluated the functional and mechanical outcomes of BA versus DMTHA in FNF in active elderly patients. Methods: This study was a randomized comparative interventional single-blinded study that was performed at Ain Shams University Hospitals. A total of 33 patients underwent DMTHA or BA after displaced FNF. Primary outcomes were functional outcome and postoperative dislocation rate. Secondary outcomes were operative time and amount of blood loss. Results: There were no significant differences between the demographic data and preoperative parameters between the two groups. There was a significant difference in the postoperative Harris Hip Score (HHS) between the two groups (P=0.01). VAS of groin pain was significantly different between the two groups (P<0.001). There was no significant difference between the two groups regarding the dislocation rate. Conclusions: The authors concluded that DMTHA offered a better functional outcome than BA with no significant complications or mortality, and there was no significant difference between DMTHA and BA in the rate of dislocation. Level of Evidence: Level II.

Dynamic trial fitting of the cup in press-fit total hip arthroplasty, a feasibility study

Trial fitting of the cup during total hip arthroplasty (THA) is done by trial cups, which do not resemble the real press-fit obtained by the definitive implant. Our goal is to judge feasibility of the X-pander® in clinical practice ; a device developed to mimic the real press-fit obtained by the definitive cup, to ensure satisfactory press-fit. In this feasibility study 45 experienced orthopaedic surgeons from 7 European countries filled in a structured survey after 78 primary THA and 31 revision surgeries, using the X-pander instead of traditional trial cups. Primary outcomes were decision change concerning cup size or further reaming and increased confidence regarding cup insertion and size. Additionally, potential association between the primary outcomes and procedure (primary or revi- sion), bone quality and experience of the surgeon were evaluated. In 33.3% of the primary and 32.2% of the revision cases the X-pander measurement changed the deci- sion and further reaming or change of cup size was decided. In 61.5% and 58.1% of respectively the primary and revision THAs the X-pander was judged to give fairly to much more reliable information than traditional trial cups. The X-pander could lead to less additional screw fixation, as stated in 37.2% of the primary and 25.8% of the revision cases and to better cup insertion in respectively 50.0% and 51.6%. This study validates that the X-pander may be a suitable option for accurate sizing and assessment of the reamed acetabulum and could replace traditional trial cups in THA.

Zurich Cementless Dual Mobility Cup for Canine Total Hip Prosthesis: Implant Characteristics and Surgical Outcome in 105 Cases

AbstractDislocation after total hip arthroplasty (THA) remains a troublesome complication, and a source of frustration for the owner and the surgeon. The dislocation rate of hip prostheses in dogs is reported to range from 4 to 15%, representing the most common short-term complication. This is especially true in large and giant breed dogs, usually requiring revision surgery. With the increase in the number of THA being performed in veterinary surgery, reducing or preventing complications such as postoperative THA dislocation will be of paramount importance. The Zurich cementless dual mobility (DM) system allows impingement-free range of angulation of 80 to 132 degrees between the ceramic head and the polyether ether ketone (PEEK) cup when combined with the range of the PEEK cup in the outer metal cup. In this article, we review the use of the DM cup in THA in large and giant breed dogs, in terms of its history, biomechanics, outcomes and complications based on 105 cases.

The Thickness of the Medial Wall of the Acetabulum Prevents Acetabular Fracture during the Insertion of a Cementless Cup in Total Hip Arthroplasty: A Biomechanical Study.

Intra-operative acetabular fracture is a total hip arthroplasty complication that can occur during cementless cup insertion, especially in osteoporotic patients. We conducted this biomechanical study to investigate the impact resistance of the acetabulum with simulated bones of different density by drop-weight impact testing. Low- and high-density polyurethane foam blocks were used as osteoporotic and healthy bone models, respectively. Polyurethane blocks were used as the acetabular cancellous bone. Composite sheets were used as the acetabu-lum's medial cortex. The testing revealed that the osteoporotic bone model's impact resistance was significantly lower than that the healthy bone model'. In the healthy bone model, even thin acetabular cancellous bone with ≥ 1 mm acetabulum medial cortex was less likely to fracture. In the osteoporotic bone model, fracture was pos-sible without ≥ 1 mm medial cortex of the acetabulum and thick acetabular cancellous bone. Although impac-tion resistance differs due to bone quality, the impaction resistance in this osteoporotic bone model was equiv-alent to that healthy bone model's when a thick medial wall was present. To avoid intra-operative acetabulum fracture, surgeons should consider both the bone quality and the thicknesses of the medial cortex and acetabu-lar cancellous bone.

Comparison of the accuracies of computed tomography-based navigation and image-free navigation for acetabular cup insertion in total hip arthroplasty in the lateral decubitus position

Image-free navigation has been proven as reliable as that using computed tomography (CT) in positioning the acetabular cup in total hip arthroplasty (THA), but previous studies rarely included hip dysplasia cases. The purpose of the present study was to determine the accuracies of CT-based navigation and image-free navigation for acetabular cup insertion, including hip dysplasia cases. Sixty-three hips were studied, including 57 with hip dysplasia. The hips were divided into two groups based on the registration point of image-free navigation. In Group I, the ipsilateral anterior superior iliac spine (ASIS) and the L5 spinous process were registered in 31 hips. In Group II, bilateral ASIS points were registered in 32 hips. Final component orientation was measured from postoperative CT scans. The accuracy of cup orientation was compared between CT-based and image-free navigation. In Group I, the cup inclination was more accurate with CT-based navigation (1.9°) than with image-free navigation (4.4°, p=.009). Cup anteversion was also more accurate with CT-based navigation (2.9°) than with image-free navigation (7.1°, p<.001). In Group II, the accuracies of cup inclination and anteversion showed no differences between CT-based and image-free navigation. The accuracy of cup positioning was better with CT-based navigation than with image-free navigation when the ipsilateral ASIS and L5 spinous process were digitized. However, accuracy was similar when bilateral ASIS points were digitized.

Descripción del posicionamiento de una copa monobloque no cementada en el posoperatorio inmediato

BackgroundAppropriate positioning of the acetabular cup in total hip arthroplasty (THA) can improve hip function, reduce wear, impingement and dislocation. The position of the cup is described as the spatial relationship between the centre of rotation of the hip and the pelvis. The aim of this study is to describe the positioning of the uncemented monoblock cup in the immediate postoperative period in patients who underwent a primary THA. MethodsDescriptive observational study. The patients were operated by 4 joints arthroplasty surgeons in 8 different hospitals, from October 2015 to August 2018. The radiological measurements were taken from the AP Pelvis Xrays of the immediate postoperative. The inclination, anteversion, lateralization, percentage of cup uncovered and the space behind the acetabular cup. Results82.05% of the cups were in the range of inclination from 36 to 48 degrees; 85.71% had an anteversion between 5 to 15 degrees, 76.56% presented a lateralization of -2 to +2mm, 94.51% of the patients didnt have a uncover cup, and 92.67% of the cups had a space behind the cup from 0 to 3mm. DiscussionIn our study the highest percentage of cups were implanted with parameters agree to the safety areas reported by various authors. Adequate positioning of the uncemented monoblock acetabular cup can be achieved with a proper indication, a surgical approach that allows an ideal three-dimensional location and an acetabulum with a good peripheral rim that provides the required press-fit.Evidence Level: III

Dual-Mobility Cup Total Hip Arthroplasty for Displaced Femoral Neck Fractures: A Retrospective Study With a Median Follow-Up of 5 Years.

Introduction:Patient outcomes following modern dual-mobility cup total hip arthroplasty (DM-THA) remains a concern. Few reports have focused on the use of modern DM-THA in the setting of Asian populations for displaced osteoporotic femoral neck fractures (FNFs). This study aimed to investigate the outcomes of Chinese population with displaced osteoporotic FNFs initially treated with modern DM-THA.Materials and Methods:Data from 112 consecutive patients (112 hips) with displaced osteoporotic FNFs initially treated with modern DM-THA during 2011-2018 were retrospectively analyzed. Follow-ups were performed at 3 months, 6 months, 12 months, and then every 1 year after surgery. The primary endpoint was the Harris Hip Score (HHS); the secondary endpoint was the main orthopedic complication rate.Results:The mean HHS improved from 58.62 (±15.79) prior to surgery to 86.13 (±9.92) at the final follow-up. The main complication rate was 14.2% (16/112). Sixteen complications in 10 patients were recorded. Of the 16 complications, there were 2 (1.7%) cases requiring revision DM-THA, 3 (2.6%) cases of loosening, 2 (1.7%) cases of migration, 3 (2.6%) intra-prosthetic dislocation (IPD), 4 (3.5%) cases of tilting, and 2 (1.7%) cases of severe wear. The need for revision was attributed to prosthesis loosening associated with poor bony quality.Conclusion:In patients with displaced osteoporotic FNFs, DM-THA may yield favorable functional outcomes and a low rate of main orthopedic complications, in particular, a low dislocation rate.

Augmented Reality System in Total Hip Arthroplasty Using Transverse Acetabular Ligament

Augmented reality (AR) is an interactive technology that enhances the real-world environment and its real objects by augmenting new computer-generated objects. It has already invaded various fields, and particularly medicine. AR has become an essential entity of computer-assisted surgeries (CAS), as it has already shown great results in both conventional surgeries as well as minimally invasive surgeries (MIS). It has been used intraoperatively in many surgeries, especially in total hip arthroplasty (THA). Most of the systems using AR intraoperatively in THA require pre-operative CT-scan and/or intraoperative X-ray imaging, which increases radiation exposure for both the medical staff and the patient and increases surgery time and cost. This paper aims to propose a new AR system that uses the transverse acetabular ligament (TAL) as a guide for defining the accurate position for placing the acetabulum cup in THA. In opposite to other AR systems, this system is an image-free system, which means that it does not require a pre-operative CT-scan or intraoperative X-ray images, thus reducing radiation exposure and the surgery time and cost.

Dual-mobility cups in total hip arthroplasty after femoral neck fractures: A retrospective study comparing outcomes between cemented and cementless fixation.

Total hip arthroplasty (THA) after femoral neck fracture (FNF) is associated with an increased risk of dislocation. The goals of our study were (1) to determine dislocation and revision rates when dual-mobility cups (DMCs) are used in these patients, (2) to analyze clinical and radiographic outcomes, survivorship, complications and mortality rate, and (3) to compare results between cemented and cementless cups. We retrospectively reviewed patients with FNF treated using DMC-THA between 2011 and 2018. A minimum 2-year follow-up was required for clinical and radiographic assessment. The clinical outcome was assessed using the Harris Hip Score (HHS) and Merlé D´Aubigné-Postel score (MDP). Radiolucent lines, osteolysis and cup loosening were analyzed. We included 105 patients (105 hips) with a mean age of 75.5 years. There were no dislocations. One patient (1.0%) underwent cup revision at 39 months for aseptic cup loosening. The mean HHS and MDP were 80.5 and 14.2 respectively at a mean follow-up of 4.1 years. A higher MDP was found in patients with cementless rather than cemented cups (15.0 vs. 13.1; p=0.006). Four patients had radiolucent lines > 1mm, around cemented cups. At 6.8 years, estimated cup survival was 98.2% for revision for aseptic loosening and 97.3% for revision for any reason. The mortality rates were 6.7% at 1 year and 23.8% at last follow-up. Our findings suggest that using DMC in THA for FNF may prevent dislocation with a low revision rate. Cementless cups had a higher MDP than cemented cups.

Functional navigation in hip resurfacing.

Acetabular malpositioning in total hip arthroplasty (THA) can result in edge loading, leading to increased wear, pseudotumours and bearing failure. Historically Lewinnek's safe zone has been the goal for optimal THA cup positioning; however, research indicates that one generic safe zone is not ideal. In hip resurfacing (HR) there is a lack of data regarding optimal position, and studies indicate that edge loading is related to increased inclination. We used a functional positioning protocol to produce patient-specific (PS) dynamic analyses, identifying individual functional ideal acetabular zones. We hypothesized that identifying and implanting into PS functional ideal zones would result in decreased edge loading and improved clinical outcomes. Fifteen adept HRs were implanted using a PS functional positioning protocol. As plans were created for standard THA acetabular position, adjustments were made intra-operatively. Dynamic post-operative analyses showed 80% of implants were appropriately positioned. The remaining 20% had edge loading, where implants had inclination ≤5° of planned positioning and 10° of planned anteversion. 60% were ≤10° of planned inclination and anteversion. No pre-operative planned positions were within 'Lewinneks's zone', indicating its questionable relevance, especially in HR. A total of 20% of patients developed pain; however, at 1 year post-operatively all patients recorded improved Oxford hip scores. This study confirms that functional positioning in HR consistently results in improved precision and accuracy in achieving the functional acetabular ideal zone, leading to improved clinical outcomes and prevention of edge loading.

Monolithic Dual Mobility Cup Total Hip Arthroplasty Has High Complication Rates With Surgical Fixation in Elderly With Femur Neck Fracture

BackgroundThis study is prospectively conducted to evaluate surgical complications of monolithic dual mobility cup total hip arthroplasty (THA) in elderly patients with fractured neck of the femur. MethodsNinety-seven patients (97 hips) with displaced femoral neck fracture who gave informed consent for participation were prospectively enrolled. Their mean age was 76.6 years (range, 60-95 years), and the mean bone mineral density T-score of neck of the femur was −2.8 (range, −1.2 to −5.5). All patients underwent THA with monolithic dual mobility cup, and computed tomography scans were obtained to evaluate radiographic parameters including anteversion, inclination, and loosening of acetabular cups, and periprosthetic acetabular fractures. ResultsWith regard to cup orientation, mean inclination angle was 40.2° (range, 23.5°-63°) and mean anteversion was 32.6° (range, 7°-66.2°). The proportion of surgical outliers was 10.3% (10/97) in inclination and 35.1% (34/97) in anteversion. Early cup loosening within 2 weeks was detected in 2 hips. Periprosthetic acetabular fractures were identified in 6 hips (6/97, 6.2%). Of the 6 fractures, 5 nondisplaced fractures were healed with conservative management, but 1 fracture with displacement eventually led to cup loosening and the patient underwent revision surgery. Reoperation rate of the monolithic dual mobility cup was 4.1% (4/97). ConclusionThe use of the monolithic dual mobility was associated with improper cup fixation and periprosthetic acetabular fractures in the elderly with poor bone stock, although the dual mobility cup lowered the risk of early dislocation after THA.

Acetabulum Cup Stability in an Early Weight-Bearing Cadaveric Model of Geriatric Posterior Wall Fractures.

Primary total hip arthroplasty (THA) has been suggested for posterior wall (PW) fractures with unfavorable features in the geriatric population. There is a paucity of studies reporting on postoperative protocols for primary THA after PW fractures. The purpose of this study was to test the biomechanical effect of immediate assisted weight-bearing on acetabulum THA cup fixation in an osteoporotic PW fracture model. Computed tomography scans of 18 geriatric PW fractures (mean age, 77 ± 8 years) were used to generate representative PW fracture. This fracture pattern, comprising 50% of the PW and 25% of the acetabulum rim, was then created in 6 female cadaveric pelves. A multihole acetabulum THA cup was implanted with line-to-line reaming and fixed with four 5-mm screws. The pelves were cyclically loaded to up to 1.8× body weight (BW) in the intact form, after fracture creation and fracture fixation. Optical markers were used to determine acceptable cup motion of less than 150 μm. Five specimens withstood 3.6× BW loading after implantation and before fracture creation. At 1.8× BW load, cup motion was nonfractured: 50 ± 24 µm (range, 5-128 µm), fractured with no fixation: 37 ± 22 µm (range, 8-74 µm), or fractured with fixation: 62 ± 39 µm (range, 5-120 µm) (P = 0.0097). Cup motion was <150 µm for all groups. This study supports the practice of allowing immediate assisted weight-bearing in patients undergoing THA with PW fractures involving up to 50% of the PW and up to 25% of the acetabular rim, with or without fixation of the PW fragment.

Is the position of dual-mobility cup in THA for femoral neck fractures optimal? A retrospective study.

Few studies have examined the relationship between the indication of total hip arthroplasty (THA) and the quality of its technical achievement. Implants mispositioning could happen more frequently while THA is performed on acute proximal femur fracture cases. The purpose of this study was to compare the frontal inclination (FTA) of double-mobility cups (DMC) in patients undergoing THA for hip osteoarthritis or fracture. This retrospective study included all patients undergoing THA for hip fracture or hip osteoarthritis. The surgical protocol was identical in all patients and included a systematic DMC implantation. In the postoperative period, the FTA was measured on anteroposterior pelvic radiographs and compared between groups. Malposition was defined for FTA values outside the 35°-55° range. The study included 97 patients: 33 men, mean age: 78.8years, 45 fractures. The misalignment rate was 55% after THA for fracture versus 33% for hip osteoarthritis (p = 0.02). The mean FTA value was 39° for "fracture" and 43° for "hip osteoarthritis" groups (p = 0.052). The risk for hip dislocation, surgical revision for mechanical or infectious cause was identical in both groups. Misalignment was more frequent when THA was achieved for an acute proximal femur fracture. Several explanations can be proposed: lesser bone quality, incomplete removal of upper acetabular osteophytes which can lead to excessive horizontalization of the cup and surgical procedure performed by younger surgeons in "fracture group". These misalignments don't cause more mechanical complications in the first months after surgery.

Dual Mobility Acetabular - Cup Total Hip Arthroplasty after Femoral Neck Fracture in the Elderly: Prospective Study on Risks of Early Dislocation in 80 Total Hip Replacements

Dual Mobility Acetabular - Cup Total Hip Arthroplasty after Femoral Neck Fracture in the Elderly: Prospective Study on Risks of Early Dislocation in 80 Total Hip Replacements

Does It Matter: Total Hip Arthroplasty or Lumbar Spinal Fusion First? Preoperative Sagittal Spinopelvic Measurements Guide Patient-Specific Surgical Strategies in Patients Requiring Both

BackgroundIn patients requiring both total hip arthroplasty (THA) and lumbar spinal fusion (LSF), consideration of preoperative sagittal spinopelvic measurements can aid in the prediction of postfusion compensatory changes in pelvic tilt (PT) and inform adjustments to traditional THA cup anteversion. This study aims to identify relationships between spinopelvic measurements and post-THA hip instability and to determine if procedure order reveals a difference in hip dislocation rate. MethodsPatients at a single practice site who received both THA and LSF between 2005 and 2015 (292: 158 = LSF prior to THA, 134 = THA prior to LSF) were retrospectively reviewed for incidents of THA instability. Those with complete radiograph series (89) had their sagittal (standing) spinopelvic profiles measured preoperatively, immediately postoperatively, and 3 months, 6 months, 1 year, 1.5 years, and 2 years postoperatively. Measured parameters included lumbar lordosis (LL), pelvic incidence (PI), PT, and sacral slope (SS). ResultsNo significant differences in dislocation rates between operative order groups were elicited (7/73 LSF first, 4/62 THA first; Z = 0.664, P = .509). Compared to nondislocators, dislocators had lower LL (−10.9) and SS (−7.8), and higher PT (+4.3) and PI-LL (+7.3). Additional risk factors for dislocation included sacral fusion (relative risk [RR] = 3.0) and revision fusion (RR = 2.7) . Predictive power of the model generated through multiple regression to characterize individual profiles of post-LSF PT compensation based on perioperative measurements was most significant at 1 year (R2 = 0.565, F = 0.000456, P = .028) and 2 years (R2 = 0.741, F = 0.031, P = .001) postoperatively. ConclusionIn performing THA after LSF, it is theoretically ideal to proceed with THA at a postfusion interval of at least 1 year, beyond which further compensatory PT change is minimal. However, the order of surgical procedure revealed no statistical difference in hip instability rates. In cases characterized by large PI-LL mismatch (larger or less predictable compensation profiles) or large SS or LL loss (considerably atypical muscle recruitment), consideration of full functional anteversion range between sitting and standing positions to account for abnormalities not appreciated with standing radiographic assessment alone may be warranted.

Supine versus lateral position for accurate positioning of acetabular cup in total hip arthroplasty using the modified Watson-Jones approach: A randomized single-blind controlled trial

BackgroundThe orientation of the acetabular cup is a critical factor for prevention of various postoperative complications in total hip arthroplasty (THA). Although most patients are treated in either supine or lateral position during surgery, it is still unclear which position is superior to achieve more accurate cup positioning. Our study was conducted in order to answer the following questions: (1) does the supine position provide a higher accuracy of cup positioning than the lateral position in THA using modified Watson-Jones approach? (2) is there any difference in the distribution of cup position between the two positions?Hypothesis Our hypothesis was that the supine position would provide a higher accuracy of cup positioning than the lateral position in THA using modified Watson-Jones approach. Patients and methodsA single-center prospective randomized study (registration number: UMIN000021627) was conducted between May 2016 and December 2017. We recruited a total of 60 participants undergoing unilateral primary cementless THA using modified Watson-Jones anterolateral approach based on the result of the sample size calculation. They were randomly assigned to either supine position (n=29) or lateral position (n=31). The cup alignment was targeted using a goniometer during surgery. The radiographic cup inclination was targeted to 40° and the radiographic cup anteversion was targeted considering the femoral stem anteversion during surgery. Postoperative cup alignment was measured by plain radiography and computed tomography. We defined the difference between postoperative and target cup angle as target error and our primary outcome was the absolute value of the target angle. As secondary outcome, the distribution of the target error was evaluated. The target errors of each inclination and anteversion were divided into 3 groups; neutral (−3°≤the target error≤3°), positive error (3°<the target error), and negative error (the target error<−3°). ResultsThe assessment of primary outcome for all recruited patients showed that supine group was significantly more accurate than lateral group in terms of radiographic inclination (2.4° vs. 4.5°, respectively, mean difference 2.1°; 95% confidence interval, 0.7 to 3.5; p<0.01). There was no significant difference in terms of radiographic cup anteversion (5.6° vs. 5.2°, mean difference 0.4°; 95% confidence interval, −1.8 to 2.6; p=0.69). The rate of positive error of anteversion in supine and lateral group was larger than that of negative value of anteversion (51.7% vs. 10.3% and 48.4% vs. 12.9%, respectively). Any acute complication (dislocation, fracture, and infection) was not found in both groups during postoperative 3 months. DiscussionIn this randomized-controlled trial, higher accuracy of acetabular cup inclination was provided by supine position than by lateral position in THA. On the other hand, there was no significant difference between both groups in terms of cup anteversion. In both groups, most cups were placed with larger anteversion than we targeted. Modified Watson-Jones approach in both positions should be performed considering these results. Study registration numberUMIN000021627.Level of evidence II, randomised controlled study (population-limited).

当院におけるdual mobility cupを用いた人工股関節全置換術の短期成績

当院におけるdual mobility cupを用いた人工股関節全置換術の短期成績

Uncemented cups with and without screw holes in primary THA: a Swedish Hip Arthroplasty Register study with 22,725 hips

Background and purpose — Uncemented cups in total hip arthroplasty (THA) are often augmented with additional screws to enhance their primary stability. We investigated whether there is a difference in the risk for revision between cups with screw holes and cups without screw holes.Patients and methods — We analyzed the risk for cup revision of uncemented cups registered in the Swedish Hip Arthroplasty Register (SHAR) between 2000 and 2017 with respe ct to the presence of screw holes. Only patients with primary osteoarthritis (OA) were included. 22,725 cups, including 12,354 without screw holes and 10,371 with screw holes, were evaluated. Revision rates at 2 and 10 years after the primary operation were analyzed.Results — At a median follow-up time of 3.4 years (0–18), 459 cup revisions were reported. The main reasons for cup revision during the whole observation time were infection, 52% of all cup revisions, and dislocation, 26% of all cup revisions. The survival rate with cup revision due to aseptic loosening as endpoint was 99.9% (95% CI 99.8–99.9) at 2 years for both cups with and cups without screw holes, and the survival rates at 10 years were 99.5% (CI 99.3–99.7) and 99.1% (CI 98.6–99.5), respectively. Cups without screw holes showed a decreased risk of revision due to any reason at both 2 years (adjusted hazard ratio [HR] 0.6, CI 0.5–0.8) and 10 years (HR 0.7, CI 0.5–0.9).Interpretation — We found a very low revision rate for aseptic loosening with modern, uncemented cup designs. Cups with screw holes had an increased risk of revision due to any reason in patients with primary OA