Long-Term Outcome on the Mal-Seating of Ceramic-on-Ceramic Articulation in Total Hip Arthroplasty

BackgroundTotal hip arthroplasty with ceramic-on-ceramic articulation aims to decrease wear, osteolysis, and aseptic loosening. A metal-backed ceramic liner was developed to reduce the risk of liner fracture. However, a significant number of cases of mal-seating of the metal-backed ceramic liner were observed in the 2000s, and there were concerns about their outcome. This review aims to investigate the long-term performance of the mal-seated ceramic liner.MethodsFrom July 2003 to March 2007, 35 ceramic-on-ceramic total hip arthroplasties were performed with the Trident acetabular system. Clinical assessment, radiological analysis, and outcome assessment were performed. The prevalence of liner mal-seating and its long-term outcomes were investigated.ResultsThere was liner mal-seating in 8 hips (22.9%). One liner was exchanged in the early postoperative period. No revision surgery was required for the remaining 7 hips at a mean follow-up of 14 years. All patients were free of hip pain with a mean Harris Hip Score of 94.7 at the most recent follow-up. No adverse event was observed.ConclusionThe long-term outcomes of the mal-seated liner were favorable. However, surgeons should exercise meticulous surgical technique to achieve a properly aligned liner within the acetabular shell to minimize this potentially correctable error.     

Patient-Specific Contact Stress Does Not Predict Polyethylene Wear Rate in a Specific Pressfit Cup

Background

The most common reason for revision total hip arthroplasty remains polyethylene wear. Development dysplasia of the hip and revision situations requires a conscious compromise of implant position. The surgeon should know about the consequence on wear via a possible change in hip contact force. The objective of this study is to investigate whether annual wear is dependent on hip contact force.

A Pilot Study of Augmented Reality Technology Applied to the Acetabular Cup Placement During Total Hip Arthroplasty

Background

We developed an acetabular cup placement device, the AR-HIP system, using augmented reality (AR). The AR-HIP system allows the surgeon to view an acetabular cup image superimposed in the surgical field through a smartphone. The smartphone also shows the placement angle of the acetabular cup. This preliminary study was performed to assess the accuracy of the AR-HIP system for acetabular cup placement during total hip arthroplasty (THA).

Complications Encountered With the Use of Constrained Acetabular Prostheses in Total Hip Arthroplasty

At our department, 46 constrained acetabular components in 38 patients were placed successively for a period of 4 years. Indications included recurrent dislocation, septic and aseptic loosening with extensive bone loss, tumor surgery with extensive bone resection, and instability due to neurologic impairment. Because 2 cup failures and 10 dislocations were observed with the constrained devices at 4 to 7 years of follow-up, the authors started to use large-diameter metal-on-metal bearings for similar indications. A series of 36 such bearings in 38 patients revealed only one cup failure and one dislocation at 2 to 4 years of follow-up. Although the 2 series are different and therefore difficult to compare, the authors recommend judicious use of constrained devices because of the high failure rate (26%) and consideration of alternative options such as the use of large-diameter metal-on-metal bearings.     

Incidence of Ceramic Fracture in Contemporary Ceramic-on-Ceramic Total Hip Arthroplasty: A Meta-analysis of Proportions

BackgroundWe performed a proportion meta-analysis of currently available data to determine the prevalence of ceramic fracture for each generation.MethodsA total of 10,571 total hip arthroplasties from 45 studies were included. Proportion meta-analysis with a random-effects model was performed to estimate the prevalence of ceramic fracture. To determine whether the ceramic fractures have a fatigue nature and a risk or latent period for the development, postoperative time lapse, patient age, and body mass index were related with ceramic fracture by metaregression analysis.ResultsAs of postoperative 2.0 to 18.8 years, the rate of ceramic fracture was 0.5% (95% CI, 0.3%-0.8%) in the forte group and 0.2% (95% CI, 0.1%-0.4%) in the delta group (P = .059). The ceramic fracture rate for each component was 0.2% (95% CI, 0.1%-0.3%) for the forte head, 0.1% (95% CI, 0.0%-0.2%) for the delta head (P = .210), 0.2% (95% CI, 0.1%-0.3%) for the forte liner, and 0.2% (95% CI, 0.1%-0.4%) for the delta liner (P = .305). The rate of ceramic fracture per 1000 patient-years was 0.9 (95% CI, 0.5-0.13) in the forte group and 0.5 (95% CI, 0.2-0.8) in the delta group (P = .072). In metaregression analysis, no significant associations were found between prevalence of ceramic fracture and postoperative time lapse, patient age, or body mass index.ConclusionsThe rate of ceramic fracture was 0.9/1000 patient-year in the forte group and 0.5/1000 patient-year in the delta group. The results of this study provide baseline data for further studies validating ceramic bearings.Level of EvidenceLevel I, meta-analysis.     

A Randomized Seven-Year Study on Performance of the Stemmed Metal M2a-Magnum and Ceramic C2a-Taper,and the Resurfacing ReCap Hip Implants

Background

The large-diameter metal-on-metal hip prostheses were expected to have low wear and reduced dislocation rate compared to the traditional metal-on-polyethylene implants. We compare 2 such prostheses, the ReCap resurfacing implant and the M2a-Magnum stemmed implant, with the C2a ceramic-on-ceramic stemmed implant as to clinical performance, serum concentrations of prosthesis metals, and the durability of the implants in a randomized, controlled clinical trial at 7 years of follow-up.

Influence of Acetabular Shell Position and Component Design on Hip Dynamic Dislocation

Background

Dislocation is a major complication following total hip arthroplasty, with risk factors such as surgical technique, implant positioning, and implant design. Literature has suggested the distance the femoral head must travel before dislocation to be a predictive factor of dislocation where smaller travel distance has increased dislocation risk. The purpose of this study was to compare 3 designs (hemispherical, metal-on-metal, and dual mobility [DM]) in terms of the dynamic dislocation distance and force required to dislocate.

Hip abduction can prevent posterior edge loading of hip replacements

Edge loading causes clinical problems for hard‐on‐hard hip replacements, and edge loading wear scars are present on the majority of retrieved components. We asked the question: are the lines of action of hip joint muscles such that edge loading can occur in a well‐designed, well‐positioned acetabular cup? A musculoskeletal model, based on cadaveric lower limb geometry, was used to calculate for each muscle, in every position within the complete range of motion, whether its contraction would safely pull the femoral head into the cup or contribute to edge loading. The results show that all the muscles that insert into the distal femur, patella, or tibia could cause edge loading of a well‐positioned cup when the hip is in deep flexion. Patients frequently use distally inserting muscles for movements requiring deep hip flexion, such as sit‐to‐stand. Importantly, the results, which are supported by in vivo data and clinical findings, also show that risk of edge loading is dramatically reduced by combining deep hip flexion with hip abduction. Patients, including those with sub‐optimally positioned cups, may be able to reduce the prevalence of edge loading by rising from chairs or stooping with the hip abducted. © 2013 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res 31:1172–1179, 2013

     

Augmented Reality- vs Accelerometer-Based Portable Navigation System to Improve the Accuracy of Acetabular Cup Placement During Total Hip Arthroplasty in the Lateral Decubitus Position

BackgroundThere have been no studies regarding the effectiveness of augmented reality (AR)-based portable navigation systems compared with accelerometer-based portable navigation systems in total hip arthroplasty (THA).MethodsWe retrospectively compared THAs performed using an AR-based portable navigation system (n = 45) and those performed using an accelerometer-based portable navigation system (n = 42). All THAs were performed with the patient in the lateral decubitus position. The primary outcome was the absolute difference between cup placement angles displayed on the navigation screen and those measured on postoperative X-ray.ResultsThe mean absolute differences were significantly smaller in the AR-based portable navigation system group than the accelerometer-based portable navigation system group in radiographic inclination (2.5° ± 1.7° vs 4.6° ± 3.1°; 95% confidence interval 1.1°-3.2°, P < .0001). Similarly, the mean absolute differences were significantly better in the AR-based portable navigation system group in radiographic anteversion (2.1° ± 1.8° vs 6.4° ± 4.2°; 95% confidence interval 3.0°-5.7°, P < .0001). Neither hip dislocation, surgical site infection, nor other complications associated with use of the navigation system occurred in either group.ConclusionThe AR-based portable navigation system may provide more precise acetabular cup placement compared with the accelerometer-based portable navigation system in THA.     

Post-Cam Design and Contact Stress on Tibial Posts in Posterior-Stabilized Total Knee Prostheses: Comparison Between a Rounded and a Squared Design

Background

The post-cam mechanism in posterior stabilized (PS) prostheses plays an important role in total knee arthroplasty (TKA). The purpose of this study is to clarify the difference of the contact stress on the tibial post between a rounded post-cam design and a squared design during deep knee flexion and at hyperextension using the three-dimensional (3D) finite element models.

The Effect of Functional Pelvic Tilt on the Three-Dimensional Acetabular Cup Orientation in Total Hip Arthroplasty Dislocations

BackgroundAnterior and posterior pelvic tilt appears to play a role in total hip arthroplasty (THA) stability. When changing from the standing to the sitting position, the pelvis typically rotates posteriorly while the hips flex and this affects the femoro-acetabular positions. This case-control study compares changes in 3-D acetabular cup orientation during functional pelvic tilt between posterior THA dislocations vs stable THAs.MethodsStanding and sitting 3-D cup orientation was compared between fifteen posterior dislocations vs 233 prospectively followed stable THAs. 3-D cup orientation was calculated using previously validated trigonometric algorithms on biplanar radiographs. Those algorithms combine the angles in the three anatomical planes (coronal inclination, transverse version, and sagittal ante-inclination) in the standing position with the change in sagittal pelvic tilt from standing to sitting to calculate the 3-D orientation in the sitting position.ResultsThe standing cup orientation of the dislocated THAs was only characterized by a lower coronal inclination (P = .039). Compared with the controls, from standing to sitting, they showed less posterior pelvic tilt (P < .001). This led to a significant lower coronal inclination (P < .001) and sagittal ante-inclination (P < .001) in the sitting position but similar transverse version (P = .366).ConclusionsComparing posterior THA dislocations to stable THAs, there is a lower increase of all three orientation angles from standing to sitting. This leads to a decreased sitting coronal inclination and sagittal ante-inclination which may lead to an increased risk of impingement ensued by THA instability. By contrast, the transverse version was not significantly different in both positions. This confirms the importance of biplanar data on functional cup orientation.Level of EvidenceDiagnostic, Level III.     

Gait alterations can reduce the risk of edge loading

Following metal‐on‐metal hip arthroplasty, edge loading (i.e., loading near the edge of a prosthesis cup) can increase wear and lead to early revision. The position and coverage angle of the prosthesis cup influence the risk of edge loading. This study investigates the effect of altered gait patterns, more specific hip, and pelvis kinematics, on the orientation of hip contact force and the consequent risk of antero‐superior edge loading using muscle driven simulations of gait. With a cup orientation of 25° anteversion and 50° inclination and a coverage angle of 168°, many gait patterns presented risk of edge loading. Specifically at terminal double support, 189 out of 405 gait patterns indicated a risk of edge loading. At this time instant, the high hip contact forces and the proximity of the hip contact force to the edge of the cup indicated the likelihood of the occurrence of edge loading. Although the cup position contributed most to edge loading, altering kinematics considerably influenced the risk of edge loading. Increased hip abduction, resulting in decreasing hip contact force magnitude, and decreased hip extension, resulting in decreased risk on edge loading, are gait strategies that could prevent edge loading. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1069–1076, 2016.     

The Formation of Stress by Acrylic Bone Cements During Fixation of the Acetabular Prosthesis

The forces developed by acrylic cement during the final phase of polymerization under conditions that simulate the cementing of the acetabular prosthesis are evaluated. Calculations show that forces of 500–1100 N may be reached in a three-point fixational system. the importance of the dimensions of the plastic and the bone and the relevance of the E-moduli are discussed.     

Learning Curve of Acetabular Cup Positioning in Total Hip Arthroplasty Using a Cumulative Summation Test for Learning Curve (LC-CUSUM)

Despite advances in surgical techniques and instrumentation, optimal cup positioning in total hip arthroplasty (THA) is challenging with a limited accuracy. We evaluated whether a learning curve exists for the optimal cup positioning, using the LC-CUSUM test (Learning curve cumulative summation test). We evaluated the first 100 consecutive THA performed by two surgeons, who had a year of fellowship training in the same teaching hospital. A learning curve of cup positioning was plotted in each series using the LC-CUSUM score. There was no significant difference of numbers of outlier between two surgeons (P = 0.079). Both surgeons completed the learning curve of optimal cup positioning before 50 procedures, and maintained competence. A substantial learning period is necessary in the optimal positioning of an acetabular cup.     

计算机辅助经髋臼长螺钉固定进钉安全区的解剖研究

目的探讨经髋臼长螺钉固定骨性钉道的安全进钉区。方法选取10具成年男性半骨盆,每个半骨盆分成髂前区、髂后区、耻骨区和坐骨区并断层。通过断层的边界参数建立三维模型,利用计算机C语言辅助程序计算全钉道在骨性区域内的钉道参数,形成钉道线的集合,钉道线在髋臼上的交点形成点阵,这些点阵的集合代表了髋臼区进钉的位置。在髋臼球中心建立三维坐标系,建立间隔15°的经纬线以定义和描述点阵所分布的区域。结果所构建的骨盆四个分区三维模型逼真反映髋臼的真实几何形态。髂前区、髂后区、耻骨区和坐骨区各自允许长达60 mm、100mm、50 mm及40 mm的螺钉安全固定,进钉区分别位于经线方向60°到150°、纬线0°到30°的区域,经线60°到150、纬线0°到75°的区域,经线-15°到45°、纬线0°到45°的区域及经线-75°到-150°、纬线0°到30°的区域。结论髋臼四个分区均能获得临床满意的长螺钉钉道安全区域,有助于指导全髋翻修术的长螺钉固定以及假体改良设计。     

Reliability of Spinopelvic Measurements That May Influence the Cup Position in Total Hip Arthroplasty

BackgroundSpinopelvic pathology has been identified as a potential risk factor for instability after total hip arthroplasty. Spinopelvic radiographic parameters used to diagnose spinopelvic disease may also impact optimal cup placement. The purpose of this study was to assess the arthroplasty surgeon accuracy in making spinopelvic measurements.MethodsFive fellowship-trained or in-training arthroplasty surgeons reviewed 44 lateral lumbar radiographs in two sessions. All evaluators were instructed how to perform measurements but had little experience in doing so. Traditional measurements included the pelvic tilt (PT), pelvic incidence (PI), and sacral slope (SS), and novel measurements included the acetabular ante-inclination (AI) and pelvic femoral angle. Surgeon measurements were compared with those made by experienced engineers. intraclass coefficients (ICCs) were calculated and interpreted.ResultsThe interobserver reliability for 4 of 5 of the spinopelvic parameters was good to excellent (ICC >0.75) with the highest reliability seen for PI measurement (ICC = 0.939). Only moderate interobserver reliability was observed for AI measurement (ICC = 0.559). Intraobserver reliability was the highest for the PI and SS, ranging from moderate to good (ICC, 0.718 to 0.896). The lowest intraobserver reliability was seen for the AI (ICC range, 0.026 to 0.545) and pelvic femoral angle (ICC range, 0.035 to 0.828). Surgeon measurements of PT and SS were compared with engineer measurements with extremely poor correlation observed (ICC <0 for all).ConclusionSurgeon intraobserver and interobserver reliability in making novel radiographic measurements was low compared with traditional radiographic measurements. Surgeon reliability in making traditional measurements of the PT and SS was very poor compared with experienced assessors using software-based measurements.     

Influence of Hip Geometry Reconstruction on Frontal Plane Hip and Knee Joint Moments During Walking Following Primary Total Hip Replacement

BackgroundFollowing total hip replacement (THR), hip geometry reconstruction parameters such as the femoral offset (FO) correlate with hip stability and wear. The purpose of this study is to determine the relationship between hip geometry parameters and knee and hip joint loading during walking.MethodsForty-one patients were examined before and a minimum of 1 year after primary THR. Pearson correlation coefficient (r) was performed to identify relationships between radiographic parameters and gait data. In addition, we divided patients into 2 groups according to the restoration of the FO (within ±5 mm vs more than 5 mm increment).ResultsThe FO and global offset (GO) showed a positive correlation with the first (r = 0.469, P = .002; r = 0.542, P < .001) and second (r = 0.365, P = .019; r = 0.484, P = .001) knee adduction moment (KAM). The neck-shaft angle revealed a negative correlation with the first hip adduction moment (r = ?0.375, P = .047). The reconstruction of FO with an increment of more than 5 mm was associated with a significant higher first KAM (+16%, P = .045) compared to the restored group.ConclusionOur findings suggest that abnormal hip and knee joint loading during walking after THR have a biomechanical background originating from hip geometry reconstruction. Patients with a high FO/GO were more likely to have an increased KAM during walking or vice versa. Surgeons need to be aware that an accurate control of FO, GO, and neck-shaft angle restoration in THR has an impact on hip and knee joint loading that may influence degenerative changes of the knee and higher wear of the artificial hip joint, respectively.     

陶瓷头对陶瓷髋臼和陶瓷头对聚乙烯髋臼髋关节置换术临床应用观察

目的：比较陶瓷头对陶瓷髋臼和陶瓷头对聚乙烯髋臼的临床效果。方法：对32例患者采用陶瓷头对陶瓷髋臼和陶瓷头对聚乙烯髋臼的全髋人工关节置换。术后对所有患者拍摄了X线片和髋臼顶部的比较性CT。结果：对25例进行了随访。时间为12-42个月（平均40个月）。发现陶瓷头对陶瓷髋臼的全部病例骨结构正常，无骨质溶解和无骨外囊肿。陶瓷-聚乙烯组影像学表现。骨盆和关节置换的X线片，头部位于中心者7例。偏离中心者1例（1mm)。在新一代陶瓷-聚乙烯压配式技术固定证实，关节置换术后磨损1mm(直线磨损率0.2mm/年）。CT表现：8例骨结构正常，无骨外囊肿或骨化表现。髋臼顶部假体周围的X线和CT表现都正常。结论：陶瓷-陶瓷假体植入后未发现颗粒存在。而在陶瓷-聚乙烯假体中则存在。陶瓷-陶瓷的关节置换在植入后的4年里无任何骨质溶解的表现。也无磨损和骨质融合的证据。陶瓷-陶瓷人工关节摩擦系数最小及寿命最长。     

Current Preclinical Testing of New Hip Arthroplasty Technologies Does Not Reflect Real-World Loadings: Capturing Patient-Specific and Activity-Related Variation in Hip Contact Forces

BackgroundTotal hip arthroplasty (THA) implants are routinely tested for their tribological performance through regulatory preclinical wear testing (eg, ISO-14242). The standardized loading conditions defined in these tests consist of simplified waveforms, which do not specifically represent in vivo loads in different groups of patients. The aim of this study is to investigate, through musculoskeletal modeling, patient-specific and activity-related variation in hip contact forces (HCFs) in a large cohort of THA patients during common activities of daily living (ADLs).MethodsA total of 132 THA patients participated in a motion-capture analysis while performing different ADLs, including walk, fast walk, stair ascent, and descent (locomotor); sit to stand, stand to sit, squat, and lunge (nonlocomotor). HCFs were then calculated using the AnyBody Modeling System and qualitatively compared across all activities. The influence of gender on HCFs was analyzed through statistical parametric mapping analysis.ResultsSystematic differences were found in HCF magnitudes and individual components in both locomotor and nonlocomotor ADLs. The qualitative analysis of the ADLs revealed a large range and a large variability in forces experienced at the hip during different activities. Significant differences in the 3-dimensional loading patterns were observed between males and females across most activities.ConclusionTHA patients present a large variability in the forces experienced at the hip joint during their daily life. The interpatient variation might partially explain the heterogeneity observed in implant survival rates. A more extensive preclinical implant testing standard under clinically relevant loading conditions has been advocated to better predict and avoid clinical wear problems.