Aims. Hip arthroplasty aims to accurately recreate joint biomechanics. Considerable attention has been paid to vertical and horizontal offset, but femoral head centre in the anteroposterior (AP) plane has received little attention. This study investigates the accuracy of restoration of joint
Reverse total shoulder arthroplasty (RTSA) has had rapidly increasingly utilization since its approval for U.S. use in 2004. RTSA accounted for 11% of extremity market procedure growth in 201. Although RTSA is widely used, there remain significant challenges in determining the location and configuration of implants to achieve optimal clinical and functional results. The goal of this study was to measure the 3D position of the shoulder joint center, relative to the center of the native glenoid face, in 16 subjects with RTSA of three different implant designs, and in 12 healthy young shoulders. CT scans of 12 healthy and 16 pre-operative shoulders were segmented to create 3D models of the scapula and humerus. A standardized bone coordinate system was defined for each bone (Figure 1). For healthy shoulders, the location of the humeral head center was measured relative to the glenoid face center. For the RTSA shoulders, a two-step measurement was required. First, 3D models of the pre-operative bones were reconstructed and oriented in the same manner as for healthy shoulders. Second, 3D model-image registration was used to determine the post-operative implant positioning relative to the bones. The 3D position and orientation of the implants and bones were determined in a sequence of six fluoroscopic images of the arm during abduction, and the mean implant-to-bone relationships were used to determine the surgical positioning of the implants (Figure 2). The RTSA
“How does the knee move?” is a question of fundamental importance for treatment of knee injuries and knee replacement design. Unfortunately, we lack unambiguous and comprehensive knee function data sets and/or consensus on how healthy knees move. One can just as easily find reports stating the natural knee has a
Purpose. To determine if clinical outcomes are correlated with
Purpose. To determine if clinical outcomes are correlated with
Introduction. Restoration of the femoral head centre during THR should theoretically improve muscle function and soft tissue tension. The aim of this study was to assess whether 3D planning and an accurately controlled neck osteotomy could help recreate hip anatomy. Methods. 100 consecutive THR patients received OPS. TM. 3D femoral planning. For each patient a 3D stem+head position was pre-operatively planned which restored the native head height, restored global offset after cup medialisation and reproduced anterior offset, in the superior-inferior, medial-lateral and anterior-posterior directions respectively. The femoral osteotomy was planned preoperatively and controlled intra-operatively with a patient specific guide. All procedures were performed through a posterior approach with a TriFit/Trinity uncemented implant combination. Post-op implant position was determined from CT. Results. The mean difference between planned and achieved head height was 0.9mm (−1.2mm to 4.6mm). The mean difference between planned and achieved medial offset was −0.9mm (−6.2mm to 3.1mm). The mean difference between planned and achieved anterior offset was 3.2mm (−0.4mm to 6.6mm). Resultant 3D change between the planned and achieved head centre was 4.4mm (0.6mm to 9.1mm). The change in anterior offset was strongly correlated (r=0.78) to the change in achieved stem anteversion in comparison to the plan; mean values of 16.3° and 10.5° respectively. Conclusions. In this single centre pilot study, femoral
Purpose: A functional
Purpopse. Few Cervical Total Disc Replacement (TDR) devices are engineered to address both the Center of Balance (COB) and the
Background. The position of the hip-joint
INTRODUCTION. Accurate knowledge of knee joint kinematics following total knee arthroplasty (TKA) is critical for evaluating the functional performance of specific implant designs. Biplane fluoroscopy is currently the most accurate method for measuring 3D knee joint kinematics in vivo during daily activities such as walking. However, the relatively small imaging field of these systems has limited measurement of knee kinematics to only a portion of the gait cycle. We developed a mobile biplane X-ray (MoBiX) fluoroscopy system that enables concurrent tracking and imaging of the knee joint for multiple cycles of overground gait. The primary aim of the present study was to measure 6-degree-of-freedom (6-DOF) knee joint kinematics for one complete cycle of overground walking. A secondary aim was to quantify the position of the knee joint
The reverse ball and socket shoulder replacement, employing a humeral socket and glenosphere, has revolutionized the treatment of patients with arthritis and rotator cuff insufficiency. The RSP (DjO Surgical, Inc., Austin, Texas) is one such device, characterized by a lateral
Introduction: The foot is a very complex structure acting as the platform for all gait patterns. At present, little is known about the exact biomechanics of the foot due to the difficulties in modeling all of the components of the foot accurately. This has made it virtually impossible to develop a complete understanding of the aetiology of many diseases of the foot including hallux rigidus. We hypothesize that sagittal plane incongruency of the rotation of the 1. st. Metatarsophalangeal Joint (MTPJ), or an increase in the tension of the intrinsic plantar flexors is responsible for the development of hallux rigidus. Materials &
Methods: Ground reaction forces and kinematic data from gait analysis together with anthropometric data from MRI scans of a 24 y.o. female were used to create a Mimics model of the articulation of a normal 1st MTPJ during a gait cycle. The
Introduction. Lateralizing the
CT-based, customised femoral stem enables optimal reconstruction of hip mechanics and leg length. However, traditional planning and execution of cup insertion may jeopardise these biomechanical parameters. The aim of this study was to examine the agreement of the preoperative planning of cup position and the final position of the cup. Thirty total hip replacements with an uncemented acetabular cup (Duraloc, DePuy) or a cemented cup (Elite-Plus, DePuy) were included. A customised femoral stem was used in all hips. On the preoperative X-rays the planned position and orientation of the cup had been marked prior to the surgery. The pre- and postoperative X-ray images were then digitised and scaled. The planned and final positions of the cup centre in the frontal plane was then measured relative to a horizontal line defined by the tear-drops and to a vertical line through the centre of the tear-drop on the operated side. In addition the concurrence between the planned and final cup size was examined. In the horizontal direction the cups were positioned 1.4 (7.6) mm (median, ±2SD) more medial than planned on the preoperative X-rays. In the vertical direction the corresponding figures were 1.2 (6.6) mm (median, ±2SD) and the cups were usually placed more cranially than was planned. The maximum discrepancy between the planned and final position was 10,6 mm in the horizontal direction (medial) and 7.1 mm in the vertical direction (cranial). In 63% of the hips there was agreement between the size of the cup planned preoperatively and the cup that was finally inserted. In 25% of the hips the final cup was larger and in 12% the final cup was smaller. In most cases the acetabular cups were inserted within a few millimetres of the planned position. The combination of a standard uncemented or cemented cup with a custom femoral stem enables the surgeon to restore hip mechanics and leg length.
Introduction: Several techniques have been described for revision of acetabulum associated with severe superior bony defects. An Oblong cup inserted without bone cement has the advantage of restoration of the
Aims. Custom triflange acetabular components (CTACs) play an important role in reconstructive orthopaedic surgery, particularly in revision total hip arthroplasty (rTHA) and pelvic tumour resection procedures. Accurate CTAC positioning is essential to successful surgical outcomes. While prior studies have explored CTAC positioning in rTHA, research focusing on tumour cases and implant flange positioning precision remains limited. Additionally, the impact of intraoperative navigation on positioning accuracy warrants further investigation. This study assesses CTAC positioning accuracy in tumour resection and rTHA cases, focusing on the differences between preoperative planning and postoperative implant positions. Methods. A multicentre observational cohort study in Australia between February 2017 and March 2021 included consecutive patients undergoing acetabular reconstruction with CTACs in rTHA (Paprosky 3A/3B defects) or tumour resection (including Enneking P2 peri-acetabular area). Of 103 eligible patients (104 hips), 34 patients (35 hips) were analyzed. Results. CTAC positioning was generally accurate, with minor deviations in cup inclination (mean 2.7°; SD 2.84°), anteversion (mean 3.6°; SD 5.04°), and rotation (mean 2.1°; SD 2.47°). Deviation of the hip
Aims. Achieving accurate implant positioning and restoring native hip biomechanics are key surgeon-controlled technical objectives in total hip arthroplasty (THA). The primary objective of this study was to compare the reproducibility of the planned preoperative
One goal of total hip arthroplasty is to restore normal hip anatomy.
The aim of this study was to compare displacement of the centre
of rotation (COR) using a standard reaming technique with a technique
in which the acetabulum was reamed immediately peripherally and
referenced off the rim. In the first cohort the acetabulum was reamed to the floor followed
by sequentially larger reamers. In the second cohort the acetabulum
was only reamed peripherally, starting with a reamer the same size
as the native femoral head. Anteroposterior pelvic radiographs were
analysed for acetabular floor depth and vertical and horizontal position
of the COR.Aims
Patients and Methods
Aims. Complex total hip arthroplasty (THA) with subtrochanteric shortening osteotomy is necessary in conditions other than developmental dysplasia of the hip (DDH) and septic arthritis sequelae with significant proximal femur migration. Our aim was to evaluate the hip centre restoration with THAs in these hips. Methods. In all, 27 THAs in 25 patients requiring THA with femoral shortening between 2012 and 2019 were assessed. Bilateral shortening was required in two patients. Subtrochanteric shortening was required in 14 out of 27 hips (51.9%) with aetiology other than DDH or septic arthritis. Vertical
Aims. The aim of this study was to compare the biomechanical models of two frequently used techniques for reconstructing severe acetabular defects with pelvic discontinuity in revision total hip arthroplasty (THA) – the Trabecular Metal Acetabular Revision System (TMARS) and custom triflange acetabular components (CTACs) – using virtual modelling. Methods. Pre- and postoperative CT scans from ten patients who underwent revision with the TMARS for a Paprosky IIIB acetabular defect with pelvic discontinuity were retrospectively collated. Computer models of a CTAC implant were designed from the preoperative CT scans of these patients. Computer models of the TMARS reconstruction were segmented from postoperative CT scans using a semi-automated method. The amount of bone removed, the implant-bone apposition that was achieved, and the restoration of the
The best treatment method of large acetabular bone defects at revision THR remains controversial. Some of the factors that need consideration are the amount of residual pelvic bone removed during revision; the contact area between the residual pelvic bone and the new implant; and the influence of the new acetabular construct on the
Aims. After failed acetabular fractures, total hip arthroplasty (THA) is a challenging procedure and considered the gold standard treatment. The complexity of the procedure depends on the fracture pattern and the initial fracture management. This study’s primary aim was to evaluate patient-reported outcome measures (PROMs) for patients who underwent delayed uncemented acetabular THA after acetabular fractures. The secondary aims were to assess the radiological outcome and the incidence of the associated complications in those patients. Methods. A total of 40 patients underwent cementless acetabular THA following failed treatment of acetabular fractures. The postoperative clinical and radiological outcomes were evaluated for all the cohort. Results. The median (interquartile range (IQR)) Oxford Hip Score (OHS) improved significantly from 9.5 (7 to 11.5), (95% confidence interval (CI) (8 to 10.6)) to 40 (39 to 44), (95% CI (40 to 43)) postoperatively at the latest follow-up (p < 0.001). It was worth noting that the initial acetabular fracture type (simple vs complex), previous acetabular treatment (ORIF vs conservative), fracture union, and restoration of anatomical
Aims. Morphological abnormalities are present in patients with developmental dysplasia of the hip (DDH). We studied and compared the pelvic anatomy and morphology between the affected hemipelvis with the unaffected side in patients with unilateral Crowe type IV DDH using 3D imaging and analysis. Methods. A total of 20 patients with unilateral Crowe-IV DDH were included in the study. The contralateral side was considered normal in all patients. A coordinate system based on the sacral base (SB) in a reconstructed pelvic model was established. The pelvic orientations (tilt, rotation, and obliquity) of the affected side were assessed by establishing a virtual anterior pelvic plane (APP). The bilateral coordinates of the anterior superior iliac spine (ASIS) and the
The advent of modular porous metal augments has ushered in a new form of treatment for acetabular bone loss. The function of an augment can be seen as reducing the size of a defect or reconstituting the anterosuperior/posteroinferior columns and/or allowing supplementary fixation. Depending on the function of the augment, the surgeon can decide on the sequence of introduction of the hemispherical shell, before or after the augment. Augments should always, however, be used with cement to form a unit with the acetabular component. Given their versatility, augments also allow the use of a hemispherical shell in a position that restores the
Aims. Dislocation of the hip remains a major complication after periacetabular tumour resection and endoprosthetic reconstruction. The position of the acetabular component is an important modifiable factor for surgeons in determining the risk of postoperative dislocation. We investigated the significance of horizontal, vertical, and sagittal displacement of the hip
Objectives. The primary objective of this study was to compare accuracy in restoring the native
Aims. The aim of this study was to examine the implant accuracy of custom-made partial pelvis replacements (PPRs) in revision total hip arthroplasty (rTHA). Custom-made implants offer an option to achieve a reconstruction in cases with severe acetabular bone loss. By analyzing implant deviation in CT and radiograph imaging and correlating early clinical complications, we aimed to optimize the usage of custom-made implants. Methods. A consecutive series of 45 (2014 to 2019) PPRs for Paprosky III defects at rTHA were analyzed comparing the preoperative planning CT scans used to manufacture the implants with postoperative CT scans and radiographs. The anteversion (AV), inclination (IC), deviation from the preoperatively planned implant position, and deviation of the
Total elbow arthroplasty (TEA) usage is increasing owing to expanded surgical indications, better implant designs, and improved long-term survival. Correct humeral implant positioning has been shown to diminish stem loading in vitro, and radiographic loosening in in the long-term. Replication of the native elbow
Background. External fixation for a fracture-dislocation to a joint like the elbow, while maintaining joint mobility is currently done after identifying the
Background. Failed ingrowth and subsequent separation of revision acetabular components from the inferior hemi-pelvis constitutes a primary mode of failure in revision total hip arthroplasty (THA). Few studies have highlighted other techniques than multiple screws and an ischial flange or hook of cages to reinforce the ischiopubic fixation of the acetabular components, nor did any authors report the use of porous metal augments in the ischium and/or pubis to reinforce ischiopubic fixation of the acetabular cup. The aims of this study were to introduce the concept of extended ischiopubic fixation into the ischium and/or pubis during revision total hip arthroplasty [Fig. 2], and to determine the early clinical outcomes and the radiographic outcomes of hips revised with inferior extended fixation. Methods. Patients who underwent revision THA utilizing the surgical technique of extended ischiopubic fixation with porous metal augments secured in the ischium and/or pubis in a single institution from 2014 to 2016 were reviewed. 16 patients were included based on the criteria of minimum 24 months clinical and radiographic follow-up. No patients were lost to follow-up. The median duration of follow-up for the overall population was 37.43 months. The patients' clinical results were assessed using the Harris Hip Score (HHS), Western Ontario and McMaster Universities Osteoarthritis (WOMAC) index and Short form (SF)-12 score and satisfaction level based on a scale with five levels at each office visit. All inpatient and outpatient records were examined for complications, including infection, intraoperative fracture, dislocation, postoperative nerve palsy, hematoma, wound complication and/or any subsequent reoperation(s). The vertical and horizontal distances of the
Summary. The mathematical model has proven to be highly accurate in measuring leg length before and after surgery to determine how leg length effects hip joint mechanics. Introduction. Leg length discrepancy (LLD) has been proven to be one of the most concerning problems associated with total hip arthroplasty (THA). Long-term follow-up studies have documented the presence of LLD having direct correlation with patient dissatisfaction, dislocation, back pain, and early complications. Several researchers sought to minimize limb length discrepancy based on pre-operative radiological templating or intra-operative measurements. While often being a common occurrence in clinical practice to compensate for LLD intra-operatively, the
INTRODUCTION. The purpose of TKA is to restore normal kinematics and functioning to diseased knees. The purpose of this study was to determine whether intraoperative kinematic data are correlated with minimum one-year outcomes following primary TKA. METHODS. We reviewed data on 185 consecutive primary TKAs in which sensor-embedded tibial trials were used to evaluate kinematic patterns following traditional ligament balancing. Procedures were performed by two board-certified arthroplasty surgeons. The same implant design and surgical approach was used for all knees. Contact locations on the medial and lateral condyles were recorded for each patient at 0°, 45° and 90° of flexion, and full flexion. Vector equations were created by contact locations on the medial and lateral sides and the vector intersections determined the
Aims. There is little information in the literature about the use of dual-mobility (DM) bearings in preventing re-dislocation in revision total hip arthroplasty (THA). The aim of this study was to compare the use of DM bearings, standard bearings, and constrained liners in revision THA for recurrent dislocation, and to identify risk factors for re-dislocation. Methods. We reviewed 86 consecutive revision THAs performed for dislocation between August 2012 and July 2019. A total of 38 revisions (44.2%) involved a DM bearing, while 39 (45.3%) and nine (10.5%) involved a standard bearing and a constrained liner, respectively. Rates of re-dislocation, re-revision for dislocation, and overall re-revision were compared. Radiographs were assessed for the positioning of the acetabular component, the restoration of the
Introduction. Recent literature has shown that RSAs successfully improve pain and functionality, however variability in range of motion and high complication rates persist. Biomechanical studies suggest that tensioning of the deltoid, resulting from deltoid lengthening, improves range of motion by increasing the moment arm. This study aims to provide clinical significance for deltoid tensioning by comparing postoperative range of motion measurements with deltoid length for 93 patients. Methods. Deltoid length measurements were performed radiographically for 93 patients. Measurements were performed on both preoperative and postoperative x-rays in order to assess deltoid lengthening. The deltoid length was measured as the distance from the infeolateral tip of the acromion to the deltoid tuberosity on the humerus for both pre- and post- x-rays. For preoperative
Glenoid baseplate orientation in reverse shoulder arthroplasty (RSA) influences clinical outcomes, complications, and failure rates. Novel technologies have been produced to decrease performance heterogeneity of low and high-volume surgeons. This study aimed to determine novice and experienced shoulder surgeon's ability to accurately characterise glenoid component orientation in an intra-operative scenario. Glenoid baseplates were implanted in eight fresh frozen cadavers by novice surgical trainees. Glenoid baseplate version, inclination, augment
Purpose: Impacted piecemeal allografts for nonce-mented hemispheric cups raises a problem of primary stability in the case of extensive bone defects. The high
Introduction. While THA is associated with positive results and long-term improvement in patient quality of life, outcomes are nonetheless associated with adverse events and post-procedural deficits related to discrepancies in leg length (LLD), offset and cup placement. Post-THA errors in these parameters are associated with gait alteration, low back pain and patient dissatisfaction. Such discrepancies often necessitate revision and increasingly lead to medical malpractice litigation. Maintaining accuracy in post-surgical leg length, offset and cup placement during THA is difficult and subject to error. The sensitivity of these factors is highlighted in studies that have shown that a change of as little as 5 degrees of flexion or abduction can induce alterations in leg length of up to several millimeters. Similarly, positioning of implants can alter global and femoral offset, affecting abductor strength, range of motion and overall physical function. Compounding the biochemical issues associated with inaccurate leg length are the costs associated with these deficits. Traditional freehand techniques of managing intra-operative parameters rely on surgeon experience and tissue tensioning to manually place components accurately. These methods, however, are only able to assess leg length and are subject to inaccuracies associated with patient movement or orientation changes during surgery. Mechanical methods of minimizing post-surgical discrepancies have been developed, such as outrigger or caliper devices, although these methods also address leg length only and provide poor feedback regarding offset and
The history of knee mechanics studies and the evolution of knee arthroplasty design have been well reported through the last decade (e.g. [1],[2]). Through the early 2000's, there was near consensus on the dominant motions occurring in the healthy knee among much of the biomechanics and orthopaedic communities. However, the past decade has seen the application of improved measurement techniques to permit accurate measurement of natural knee motion during activities like walking and running. The results of these studies suggest healthy knee motion is more complex than previously thought, and therefore, design of suitable arthroplasty devices more difficult. The purpose of this paper is to briefly review the knee biomechanics literature before 2008, to present newer studies for walking and running, and to discuss the implications of these findings for the design of knee replacement implants that seek to replicate physiologic knee motions. Many surgeons point to Brantigan and Voshell [3], an anatomic study of over one hundred specimens focusing on the ligamentous and passive stabilizers of the knee, as being an important influence in their thinking about normal knee function. M.A.R. Freeman and colleagues in London claim particular influence from this work, which motivated their extensive series of MR-based knee studies reported in 2000 [4,5,6]. These papers, perhaps more than any others, are responsible for the common impression that knee kinematics are well and simply described as having a ‘medial pivot’ pattern, where the medial condyle remains stationary on the tibial plateau while the lateral condyle translates posteriorly with knee flexion. Indeed, subsequent studies in healthy and arthritic knees during squatting and kneeling [7,8,9] and healthy and ACL-deficient knees during deep knee bends [10,11] show patterns of motion quite similar to those reported by Freeman and coworkers. These studies make a convincing case for how the healthy knee moves during squatting, kneeling and lunging activities. However, these studies are essentially silent on knee motions during ambulatory activities like walking, running and stair-climbing; activities which most agree are critically important to a high-function lifestyle. In 2008 Koo and Andriacchi reported a motion laboratory study of walking in 46 young healthy individuals and found that the stance phase knee
Local anatomical abnormalities vary in congenital hip disease patients. Authors often present early to mid-term total hip arthroplasty clinical outcomes using different techniques and implants randomly on patients with different types of the disease, making same conclusions difficult. We report long term outcomes (13 to 23 years) of the treatment of low and high dislocation cases (separately) with total hip arthroplasty using TM technology acetabular cups (Implex initially and then Zimmer) and short fluted conical (Zimmer) femoral stems. From 2000 to 2010, 418 congenital hip disease hip joints were treated in our department with total hip arthroplasty. According to Hartofilakidis et al's classification, 230 hips had dysplasia, 101 low dislocation, (group A) and 87 high dislocation (group B). Pre-operative and post-operative values, at regular intervals, of HHS, SF-12, WOMAC, OHS and HOOS were available for all patients. Patient, surgeon and implant related failures and complications were recorded for all patients. In all cases an attempt was made to restore hip
Lateralization of the reverse arthroplasty may be desirable to more effectively tension the remaining rotator cuff, decrease scapular notching, improve the cosmetic appearance of the shoulder, and improve stability as well as the arc of motion prior to impingement. There are two primary options to lateralise a reverse shoulder arthroplasty: bone graft with a long post (BIO-RSA) vs. using metal. The two metal options generally include a thicker glenosphere or a thicker glenoid baseplate. Potential benefits of a BIO-RSA include lateralization of the glenoid
Lower back pain (LBP) is a worldwide clinical problem and a prominent area for research. Numerous in vitro biomechanical studies on spine specimens have been undertaken, attempting to understand spinal response to loading and possible factors contributing to LBP. However, despite employing similar testing protocols, there are challenges in replicating in vivo conditions and significant variations in published results. The aim of this study was to use the University of Bath (UoB) spine simulator to perform tests to highlight the major limitations associated with six degree of freedom (DOF) dynamic spine testing. A steel helical spring was used as a validation model and was potted in Wood's metal. Six porcine lumbar spinal motion segments were harvested and dissected to produce isolated spinal disc specimens. These were potted in Wood's metal, ensuring the midplane of the disc remained horizontal and then sprayed with 0.9% saline and wrapped in saline-soaked tissue and plastic wrap to prevent dehydration. A 400N axial preload was used for spinal specimens. Specimens were tested under the stiffness and flexibility protocols. Tests were performed using the UoB custom 6-axis spine simulator with coordinate axes. Tests comprised five cycles with data acquired at 100Hz. Stiffness and flexibility matrices were evaluated from the last three motion cycles using the linear least squares method. According to theory, inverted flexibility matrices should equal stiffness matrices. In the case of the spring, the matrices matched analytical solutions and inverted flexibility matrices were equivalent to stiffness matrices. Matrices from the spinal tests demonstrated some symmetry, with similarities between inverted flexibility- and stiffness matrices, though these were unequal overall. Matrix element values were significantly affected by displacements assumed to occur at disc centre. Spring tests proved that for linear, elastic specimens, the spine simulator functioned as expected. However, multiple factors limit the confidence in spine test results.
Accurate cup placement in total hip arthroplasty (THA) for the patients with developmental dysplasia of the hip (DDH) is one of the challenges due to distinctive bone deformity. Robotic-arm assisted system have been developed to improve the accuracy of implant placement. This study aimed to compare the accuracy of robotic-arm assisted (Robo-THA), CT-based navigated (Navi-THA), and manual (M-THA) cup position and orientation in THA for DDH. A total of 285 patients (335 hips) including 202 M-THAs, 45 Navi-THAs, and 88 Robo-THA were analyzed. The choice of procedure followed the patient's preferences. Horizontal and vertical
Aims. Only a small number of studies exist that report the results of EBM-produced porous coated trabecular titanium cups in primary total hip arthroplasty (THA). This study aims to investigate the patient satisfaction level, clinical function and radiographic outcomes of the patients who underwent THA using an EBM-produced porous coated titanium cup. Patients and Methods. A total of 32 patients who underwent primary THA with using an EBM-produced porous coated titanium cup from five hospitals between May and December, 2012 were retrospectively reviewed. Five patients were lost prior to the minimum 6-year follow-up. Clinical and radiographic outcomes were analyzed with an average follow-up of 81.48 (range: 77.00–87.00) months. Results. The median HHS and SF-36 scores improved significantly while the WOMAC Osteoarthritis Index decreased significantly at the latest follow-up (p<0.001). Eighteen (66.7%) patients rated their satisfaction level as very satisfied, 6 (22.2%) as satisfied, 2 (7.4%) as neutral and 1(3.7%) as dissatisfied. No intraoperative or postoperative complications were identified, including aseptic cup loosening, hip dislocation, periprosthetic joint infection, periprosthetic fracture, nerve palsy, hematoma. At the latest follow-up, all cups were considered to have achieved fixation via bone ingrowth with three or more of the five signs occurring in the most recent X-ray. However, three cups revealed radiolucent lines with a width of less than 1 mm. These radiolucent lines were distributed in the DeLee-Charnley zone 1 in 1 patient, zone 3 in another patient and the area between zone1 and zone 2 in an additional patient. The latest postoperative
Purpose of the study: The extramedullary anatomy of the femur must be reproduced during total hip arthroplasty in order to ensure correct tension on the gluteus muscles. This requires:. correct offset of the femur, measured as the distance between the center of the head and the anatomic axis of the shaft;. offset of the
Dual-mobility (DM) bearings are effective to mitigate dislocation in revision total hip arthroplasty (THA). However, data on its use for treating dislocation is scarce. Aim of this study was to compare DM bearings, standard bearings and constrained liner (CL) in revision THA for recurrent dislocation and to identify risk factors for re-dislocation. We reviewed 100 consecutive revision THAs performed for dislocation from 2012 and 2019. 45 hips (45%) received a DM construct, while 44 hips (44%) and 11 hips (11%) had a standard bearing and CL, respectively. Rates of re-dislocation, re-revision for dislocation and overall re-revision were compared. Radiographs were assessed for cup positioning, restoration of
Aims. There is an increased risk of dislocation of the hip after the resection of a periacetabular tumour and endoprosthetic reconstruction of the defect in the hemipelvis. The aim of this study was to determine the rate and timing of dislocation and to identify its risk factors. Methods. To determine the dislocation rate, we conducted a retrospective single-institution study of 441 patients with a periacetabular tumour who had undergone a standard modular hemipelvic endoprosthetic reconstruction between 2003 and 2019. After excluding ineligible patients, 420 patients were enrolled. Patient-specific, resection-specific, and reconstruction-specific variables were studied using univariate and multivariate analyses. Results. The dislocation rate was 9.3% (n = 41). Dislocation was most likely to occur in the first three months after surgery. Four independent risk factors were found, one of which was older age at operation (p = 0.039). The odds ratios (ORs) of those aged ≥ 60 years and 30 to 60 years were 8.50 and 4.64, respectively, compared with those aged < 30 years. The other three risk factors were resection of gluteus maximus (p = 0.010, OR = 5.8), vertical shift of the
Robotic assisted surgery aims to reduce surgical errors in implant positioning and better restore native hip biomechanics compared to conventional techniques for total hip arthroplasty (THA). The primary objective of this study was to compare accuracy in restoring the native
INTRODUCTION. Useful feedback from a Total Knee Replacement (TKR) can be obtained from post-surgery in-vivo assessments. Dynamic Fluoroscopy and 3D model registration using the method of Banks and Hodge (1996) [1] can be used to measure TKR kinematics to within 1° of rotation and 0.5mm of translation, determine tibio-femoral contact locations and
Two critical steps in achieving optimal results and minimizing complications (dislocation, lengthening, and intraoperative fracture) are careful preoperative planning and more recently, the option of intraoperative imaging in order to optimise accurate and reproducible total hip replacement. The important issues to ascertain are relative limb length, offset and
Background. Aseptic loosening is the leading cause of total knee arthroplasty (TKA) failure in the long term, of which osteolysis from polyethylene wear debris remains a problem that can limit the lifetime of TKA past the second decade. To help speed up design innovations, our goal was to develop a computational framework that could efficiently predict the effect of many sources of variability on TKA wear—including design, surgical, and patient variability. Methods. We developed a computational framework for predicting TKA contact mechanics and wear. The framework accepts multiple forms of input data: patient-specific, population-specific, or standardized motions and forces. CAD models are used to create the FEA mesh. An analytical wear model, calibrated from materials testing (wheel-on-flat) experiments, is fully integrated into the FEA process. Isight execution engine runs a design of experiments (DOE) analysis with an outcome variable, such as volumetric wear, to guide statistical model output. We report two DOE applications to test the utility of the computational framework for performing large variable studies in an efficient manner: one to test the sensitivity of TKA wear to the femoral
Purpose: Despite good clinical results of the reverse total shoulder arthroplasty inferior scapular notching remains a concern. The aim of this study was to evaluate the effect of 6 different parameters on notching. Materials and Methods: An average shape A-P view 2-D computer model of scapula was created, using data from 200 scapulae, so that the position of the glenoid and humeral component could be changed, as well as design features such as depth of the polyethylene insert, size of glenosphere and
Purpose: We hypothesized that lateralization of the RSA, with a glenoid bone graft taken from the osteotomised humeral head, would prevent those problems without increasing torque on the glenoid component by keeping the
Aim: The assessment of shoulder mobility is essential for clinical follow-up of shoulder treatment. Only a few high sophisticated instruments for objective measurements of shoulder mobility are available. The interobserver dependency of conventional goniometer measurements is high. In the 1990s an isokinetic measuring system of BIODEX Inc. was introduced, which is a very complex but valid instrument. Since 2008 a new user-friendly system (DynaPort ShoulderTest-System) is available. Aim of this study is the validation of this measuring instrument with the BIODEX-System. Methods: The DynaPort ShoulderTest-System is a small, light-weighted three-dimensional gyroscope that is fixed on the distal upper patient arm, recording abduction, fiexion and rotation. For direct comparison we fixed the DynaPort on the lever arm of the BIODEX-system. The accuracy of measurement was determined at different positions, angles and distances from the
Detection of clinical situations are the most difficult for primary THA and factors which determine the complexity. Results of 2368 primary THA performed by one surgeon in 1923 patients with various hip pathologies from 2004 to 2016 were analyzed. The time of the surgery, the bloodloss, the features of the surgical technique, the implants used, and the incidence of complications and revisions were assessed and X-ray analysis was performed. Difficult cases of primary hip arthroplasty include severe dysplasia (types B2, C1, and C2 according to the Hartofilakidis classification), post-traumatic segmental acetabular defects and pelvic discontinuity, protrusio acetabuli, iatrogenic bone ankylosis and consequences of proximal femur fractures with significant shortening of the limb. X-ray signs of difficulty included an interruption of the Shenton line of 2 cm or more (except for acute fractures of proximal femur), the femoral neck-shaft angle less than 100°, and the horizontal distance from Kohler line to
Introduction: Recent studies showed that the position of the
Purpose of the study: The aim of this biomechanical study was to assess the performance of the deltoid muscle in the absence of a rotator cuff using different models for shoulder prosthesis. Material and methods: A computer model reproducing the three dimensions of the glenohumeral joint was use to analyze the force of the deltoid muscle during abduction movements in shoulders devoid of a rotator cuff. The three heads of the deltoid were analyzed in order to determine the most effective level of muscle tension. The lever arm of the deltoid was measured from 0–90° abduction. Using this 3D model, we simulated implantation of six different models of reversed prostheses in order to assess the biomechanical situation which would be the most favorable for the deltoid. Performance of the normal deltoid was compared with the performance of the deltoid after implantation of an anatomic prosthesis and after implantation of an reversed prosthesis. Several variables were studied: medial offset of the
Two critical steps in achieving optimal results and minimizing complications (dislocation, lengthening, and intra-operative fracture) are careful pre-operative planning and more recently, the option of intra-operative imaging in order to optimise accurate and reproducible total hip replacement. The important issues to ascertain are relative limb length, offset and
The 3D interplay between femoral component placement on contact stresses and range of motion of hip resurfacing was investigated with a hip model. Pre- and post-operative contours of the bone geometry and the gluteus medius were obtained from grey-value CT-segmentations. The joint contact forces and stresses were simulated for variations in component placement during a normal gait. The effect of component placement on range of motion was determined with a collision model. The contact forces were not increased with optimal component placement due to the compensatory effect of the medialisation of the
Introduction: Operative treatment of secondary osteoarthritis due to congenital hip disease (CHD) in adults presents a challenging issue. Various classifications have been proposed for congenital hip disease in search for the best treatment option. Aim of this prospective study is to find measurements important in preoperative planning and their correlation with postoperative results. Materials and Methods: We have included 64 patients (70 hips) with CHD consecutively scheduled for operation. Preoperatively congenital hip disease was classified according to Crowe, Hartofilakidis and Eftekhar and
INTRODUCTION. The medial-stabilised (MS) knee implant, characterised by a spherical medial condyle on the femoral component and a medially congruent tibial bearing, was developed to improve knee kinematics and stability relative to performance obtained in posterior-stabilised (PS) and cruciate-retaining (CR) designs. We aimed to compare in vivo six-degree-of-freedom (6-DOF) kinematics during overground walking for these three knee designs. METHODS. Seventy-five patients (42 males, 33 females, age 68.4±6.6 years) listed for total knee arthroplasty (TKA) surgery were recruited to this study, which was approved by the relevant Human Research Ethics committees. Each patient was randomly- assigned a PS, CR or MS knee (Medacta International AB, Switzerland) resulting in three groups of 23, 26 and 26 patients, respectively. Patients visited the Biomotion Laboratory at the University of Melbourne 6±1.1 months after surgery, where they walked overground at their self-selected speed. A custom Mobile Biplane X-ray (MoBiX) imaging system tracked and imaged the implanted knee at 200 Hz. The MoBiX system measures 6-DOF tibiofemoral kinematics of TKA knees during overground gait with maximum RMS errors of 0.65° and 0.33 mm for rotations and translations, respectively. RESULTS AND DISCUSSION. Mean walking speeds for the three groups were not significantly different (PS, 0.86±0.14 m/s CR, 0.82±0.17 m/s and MS, 0.87±0.14 m/s, p>0.25). While most kinematic parameters were similar for the PS and CR groups, mean peak-to-peak anterior drawer was greater for PS (9.89 mm) than CR (7.75 mm, p=0.004), which in turn was greater than that for MS (4.43 mm, p<0.001). Mean tibial external rotation was greater for MS than PS (by 3.12°, p=0.033) and CR (by 3.34°, p=0.029). Anterior drawer and lateral shift were highly coupled to external rotation for MS but not so for PS and CR. The contact centres on the tibial bearing translated predominantly in the anterior-posterior direction for all three designs. Peak-to-peak anterior-posterior translation of the contact centres in the medial compartment was largest for PS (7.09 mm) followed by CR (5.45 mm, p=0.003) and MS (2.89 mm, p<0.001). The contact centre in the lateral compartment was located 2.5 mm more laterally for MS than PS and CR (p<0.001). The
Purpose of the study: The majority of acetabular bone defects observed during revision hip surgery can be treated with a hemispheric implant, associated or not with a bone graft. In many patients however, loss of bone stock is so great that a more complex system must be used with a sustaining ring, multilobulated implants, or massive allografts. All have their technical difficulties or problems with fixation. The purpose of this work was to evaluate a new technique for acetabular reconstruction using modular implants fashioned with a new biomaterial, porous tantalum, which had specific properties favoring osteointegration. Material and methods: These modular implants were fashioned so as to enable reconstruction of the acetabular cavity in cases with complex loss of bone stock. The design allows simultaneous biological incorporation and mechanical support with a press-fit hemispheric cup. These implants were used for 16 hips (16 patients, 12 women and 4 men, mean age 63.6 years, age range 34–86 years). These patients were followed for 31.9 months on average (range 24–39 months). The acetabular defects were Paprosky 2A (n=1), 2B ‘n=3), 2C (n=1), 3A (n=5), 3B (n=6). On average, these patients had undergone 2.8 cup replacements (1–9) on the same hip. Results: The mean Harris hip score improved from 39.31 (range 33–52) preoperatively to 75.18 (range 52–92) at last follow-up. Preoperatively, the
The human acetabulofemoral joint is commonly modelled as a pure ball-and-socket joint, but there has been no quantitative assessment of this assumption in the literature. Our aim was to test the limits and validity of this hypothesis. We performed experiments on four adult cadavers. Cortical pins, each equipped with a marker cluster, were implanted in the pelvis and the femur. Movements were recorded using stereophotogrammetry while an operator rotated the cadaver’s acetabulofemoral joint, exploiting the widest possible range of movement. The functional consistency of the acetabulofemoral joint as a pure spherical joint was assessed by comparing the magnitude of the translations of the hip joint centre as obtained on cadavers, with the
Purpose: The authors would like to report a technical innovation in cemented hip arthroplasty. The new device, a “rim cutter” (patent pending) was designed in Exeter and aims at improving the surgical technique of insertion of cemented sockets. The principle aim of this innovation is to cut a rim around the periphery of the acetabulum to a set depth so that the flange of the socket seats into this rim and thus by sealing the space underneath the flange, there is a sustained rise in cement injection pressure behind the socket during implantation. This, improves cement macro and micro interlock, creates a congruent cement mantle with no radioluciencies, especially in the highly predictive DeLee-Charnley Zone I. Materials and methods: A retrospective clinical study was performed in order to assess the radiological result of the use of the rim cutter. Two groups of patients with 30 in each group (consecutive cases) were enrolled in the present study. In group A, the rim cutter device was used while in group B, the acetabulum was prepared without the use of the rim cutter. In all cases an Exeter contemporary cup and stem were used. All cases were evaluated with postoperative radiographs which were analysed to record the anatomic measurements with regard to:. i)
INTRODUCTION. Lumbar total disc replacement (TDR) is an alternative treatment to avoid fusion related adverse events, specifically adjacent segment disease. New generation of elastomeric non-articulating devices have been developed to more effectively replicate the shock absorption and flexural stiffness of native disc. This study reports 5 years clinical and radiographic outcomes, range of motion and position of the
Introduction. The viscoelastic cervical disk prosthesis CP-ESP is an innovative one-piece deformable but cohesive interbody spacer. It is an evolution of the LP-ESP lumbar disk implanted since 2006. The implant provides 6 full degrees of freedom including shock absorption. The design allows a limitation for rotation and translation with resistance to motion (elastic return property) aimed at avoiding overload of the posterior facets. The
Two critical steps in achieving optimal results and minimizing complications (dislocation, lengthening, and intra-operative fracture) are careful pre-operative planning and more recently, the option of intra-operative imaging in order to optimise accurate and reproducible total hip replacement. The important issues to ascertain are relative limb length, offset and
Aims: The aim of the study was to determine the accuracy of the kinematical determination of the
Reverse total shoulder arthroplasty (R-TSA) converts the glenohumeral joint into a ball-and-socket articulation by implanting a metal glenosphere on the glenoid and a concave polyethylene articulation in the humerus. This design increases the stability of the shoulder and is indicated for the treatment of end-stage shoulder arthropathy with significant rotator cuff deficiency. To minimise the risk of loosening, the glenosphere is often medialised (to keep the
Introduction. Primary stability of the Burch-Schneider ring (BSR) in case of acetabular revision is discussed controversial. In a retrospective two centre cohort study we analyzed the influence of the mode of screw fixation and the restoration of the
Introduction and Objectives: We compared the clinical and radiographic results of patients with JRA and primary arthritis using a non-cemented THR with an alumina-alumina THA. Materials and Methods: We studied 29 THR (Cerafit cup and Multicone stem) implanted in 19 patients with JRA in group 1 and 135 with primary arthritis in group 2. Mean follow-up was 59.0 months. It was seen that 13 hips in group 1 had moderate-severe acetabular protrusion and allograft was used in 12 hips. The
Introduction. Wear debris induced osteolysis and loosening continue to be causes of clinical failure in total knee replacement (TKR). Laboratory simulation aims to predict the wear of TKR bearings under specific loading and motion conditions. However, the conditions applied may have significant influence on the study outcomes (1). The aim of this study was to examine the influence of femoral setup and kinematic inputs on the wear of a conventional polyethylene fixed bearing TKR through experimental and computational models. Methods. Six right Sigma CR fixed bearing TKRs (DePuy Synthes, Leeds, UK) with curved polyethylene inserts (GVF, GUR1020 UHMWPE) were tested in Prosim knee simulator (Simulator Solutions, UK). The femoral bearing was set up with the
Two critical steps in achieving optimal results and minimizing complications (dislocation, lengthening, and intraoperative fracture) are careful preoperative planning and more recently, the option of intraoperative imaging in order to optimise accurate and reproducible total hip replacement. The important issues to ascertain are relative limb length, offset and
Aims: To establish the frequency of achieving the desired prosthesis position in an uncemented total hip replacement and the effect of the position on outcome. Methods: We reviewed the earliest and most recent available post-operative pelvic x-rays of 96 patients who had undergone a total hip replacement between March 1992 and December 1995. A press þt hydroxyapatite coated cup and stem were used in all cases (CSF &
JRI respectively). We assessed the following parameters:
Lateralizing the
The elements of my routine pre-operative planning include skin and scar assessment, the limb length (physical exam and radiographic assessments), the socket type, the stem type, and radiographic templating. Blood management is rarely an issue for primary total hips today and I generally do not recommend pre-operative autologous donation. I currently use a low molecular weight heparin for venous thromboembolic prophylaxis for most all patients. All of my patients have pre-operative medical clearance from a hospital intensivist. A press-fit modular cementless socket is my “workhorse”, although I occasionally use supplemental fixation with spikes (low bone density) or screws (shallow or otherwise deficient hemisphere). Cemented fixation is reserved for hips with radiation necrosis. I use a dual-offset tapered cementless stem in most cases but will use a modular stem in dysplastic, post-traumatic, or severely osteoporotic femurs. I template every case. My goals are to determine component sizes - “the part inside the bone” and improve the biomechanics of the hip – “the part outside the bone”. Sizing is relatively straightforward. For the socket, I use the teardrop and the superior bony edge as landmarks for size and position. I use a Johnson's lateral view radiograph to assess socket version and anterior osteophytes. With a tapered stem, proximal fit on the AP radiograph is the goal and the stem does not need to be canal filling. For the neck resection, I reference off the lesser trochanter. Medialisation of the hip
Abstract. Objectives. Impingement in total hip replacements (THRs), including bone-on-bone impingement, can lead to complications such as dislocation and loosening. The aim of this study was to investigate how the location of the anterior inferior iliac spine (AIIS) affected the range of motion before impingement. Methods. A cohort of 25 CT scans (50 hips) were assessed and nine hips were selected with a range of AIIS locations relative to the hip joint centre. The selected CT Scans were converted to solid models (ScanIP) and THR components (DePuy Synthes) were virtually implanted (Solidworks). Flexion angles of 100⁰, 110⁰, and 120⁰ were applied to the femur, each followed by internal rotation to the point of impingement. The lateral, superior and anterior extent of the AIIS from the
Objectives. To date, no study has considered the impact of acromial morphology on shoulder range of movement (ROM). The purpose of our study was to evaluate the effects of lateralization of the
There are a variety of sizes currently available for reverse total shoulder arthroplasty (RTSA) implant systems. Common sizing options include a smaller 36 to 38 mm or a larger 40 to 42 mm glenosphere, and are typically selected based on surgeon preference or patient size. Previous studies have only evaluated the abduction and adduction range of motion within a single plane of elevation, providing a limited view of the joint's possible range of motion. The purpose of this study was to use computer modeling to evaluate the abduction and adduction range of motion across multiple planes of elevation for a range of glenosphere sizes. Computed tomography images of four cadaveric specimens (age: 54 ± 24 years) were used to obtain the osseous anatomy to be utilised in the model. Solid-body motion studies of the RTSA models were constructed with varying glenosphere diameters of 33, 36, 39, 42, and 45 mm in Solidworks (Dassault Systems, US). The implant components were scaled, while maintaining a consistent
Although total hip arthroplasty is highly successful for treatment of osteoarthrosis of hip joint, it is skill demanding surgery to perform and even more challenging in case of revision with bone defects. There are many options available for reconstruction of acetabular bony defects. Here, we evaluate the outcome of acetabular bony defect reconstructed with trabecular metal augments in short term. We performed, 22 revision total hip arthroplasties and 6 primary total hip arthroplasties (total 28 in 28 patients) using trabecular metal augments to reconstruct acetabular defect between 2011 to 2015. Out of these 28 patients, 18 were males and 10 were females. Mean age of these patients was 61.2 years (range: 46 years to 79 years). Pre-operative templating was done for all cases and need for trabecular metal augments was anticipated in all cases. All cases were classified according to Paprosky classification for acetabular bone defects. Out of 28 patients, 3 had type 2B, 1 had type 2C, 18 had type 3A and 6 had type 3B acetabular defects. Post operatively, all patients were followed at regular interval for their clinical and radiological outcome. An average follow up was 20.1 months (range: 6 months to 42.5 months). We assessed clinical outcome in the form of Herris hip score (HHS) and radiological outcomes in form of osteolysis in acetabular zones and osseointegration, according to the criteria of Moore. The average Harris hip score (HHS) was improved from 58.0 preoperatively to 87.2 postoperatively. The average degree of cup abduction at the final follow up was 44.29. The
Aims. Scapular notching is a frequently observed radiographic phenomenon
in reverse shoulder arthroplasty (RSA), signifying impingement of
components. The purposes of this study were to evaluate the effect
of glenoid component size and glenosphere type on impingement-free
range of movement (ROM) for extension and internal and external
rotation in a virtual RSA model, and to determine the optimal configuration
to reduce the incidence of friction-type scapular notching. Materials and Methods. Preoperative CT scans obtained in 21 patients (three male, 18
female) with primary osteoarthritis were analyzed using modelling
software. Two concurrent factors were tested for impingement-free
ROM and translation of the
During revision THR, the surgery is often difficult and compromised due to lack of patient's bone especially in the pelvis. Any extra bone in the acetabulum is expected to be of advantage to the patient and the surgeon. The aim of this study was to see if preservation of medial acetabular osteophyte in uncemented total hip replacement had any adverse effect on the prosthesis survival or patient satisfaction. Conventional acetabular preparation involves reaming down to the true floor. This not only medialises the
Introduction and Aims. There are many variables that can affect the occurrence and severity of edge loading in hip replacement. A translational mismatch between the
Purpose. The positon of short stem is affected by the native anatomy of femoral neck and also by fixation mechanism dependent on design. As a consequence, it has been speculated that restoration of hip geometry might be limited in total hip arthroplasty (THA) using short stem. Therefore, the present study assessed the predictability of restoration of hip geometry using two different CCD-angled short stem engaging the lateral cortex. Materials and Methods. The 60 patients included 15 females and 45 males. The average age was 48.0 years with average BMI 24.2. Biomechanical parameters of hip geometry were analysed on postoperative calibrated radiographs in 30 consecutive primary unilateral THAs using short stem (Metha®, B. Braun Aesculap, Tuttlingen, Germany) with 120° CCD angle (group I) and 30 match controlled cases with 135° CCD angle (group II) and compared to those of the contralateral hip without deformity. The matching process was done before collecting the radiographic measurements by two blinded observer and was for sex, age ± 5 years, and BMI ± 7 units in that order. Results. Head length was short in 40%, 67%, medium in 37%, 23% and large in 23%, 10% of the patients in each group respectively with no significant difference in between group (p=0.11). The discrepancies of horizontal hip
The primary goals of successful rTSA (Reverse Total Shoulder Arthroplasty) are pain relief, improved shoulder motion and function with the restoration of patient independence. These goals can be achieved by optimal prosthesis design and surgical technique. Historically there have been two predominant reverse shoulder design philosophies: the traditional valgus 155-degree neck-shaft angle with a medialised
Introduction. The longevity of total hip arthroplasty (THA) is dependent on acetabular component position. We measured the reliability and accuracy of a CT-based navigation system to achieve the intended acetabular component position and orientation using three dimensional imaging. The purpose of the current study was to determine if the CT-guided robotic navigation system could accurately achieve the desired acetabular component position (center of rotation (COR)) and orientation (inclination and anteversion). The postoperative orientation and location of the components was determined in 20 patients undergoing THA using CT images, the gold standard for acetabular component orientation. Methods. Twenty primary unilateral THA patients were enrolled in this IRB-approved, prospective cohort study to assess the accuracy of the robotic navigation system. Pre- and post-operative CT exams were obtained and aligned 3D segmented models were used to measure the difference in
Reverse total shoulder arthroplasty (RTSA) is an increasingly common treatment for osteoarthritic shoulders with irreparable rotator cuff tears. Although very successful in alleviating pain and restoring some function, there is little objective information relating geometric changes imposed by the reverse shoulder and arm function, particularly the moment generating capacity of the shoulder muscles. Recent modeling studies of reverse shoulders have shown significant variation in deltoid muscle moment arms over a typical range of humeral offset locations in shoulders with RTSA. The goal of this study was to investigate the sensitivity of muscle moment arms as a function of varying the joint center and humeral offset in three representative RTSA subjects that spanned the anatomical range from our previous study cohort. We hypothesized there may exist a more beneficial joint implant placement, measured by muscle moment arms, compared to the actual surgical implant configuration. A 12 degree of freedom, subject-specific model was used to represent the shoulders of three patients with RTSA for whom fluoroscopic measurements of scapular and humeral kinematics during abduction had been obtained. The computer model used subject-specific in vivo abduction kinematics and systematically varied humeral offset locations over 1521 different perturbations from the surgical placement to determine moment arms for the anterior, lateral and posterior aspects of the deltoid muscle. The humeral offset was varied from its surgical position ±4 mm in the anterior/posterior direction, ±12mm in the medial/lateral direction, and −10 mm to 14 mm in the superior/inferior direction. The anterior deltoid moment arm varied up to 20 mm with humeral offset and
Introduction and Aims. In order to improve the longevity and design of an implant, a wide range of pre-clinical testing conditions should be considered including variations in surgical delivery, and patients' anatomy and biomechanics. The aim of this research study was to determine the effect of the acetabular cup inclination angle with different levels of joint centre mismatch on the magnitude of dynamic microseparation, occurrence and severity of edge loading and the resultant wear rates in a hip joint simulator. Methods. The six-station Leeds Mark II Anatomical Physiological Hip Joint Simulator and 36mm diameter ceramic-on-ceramic bearings (BIOLOX® delta) were used in this study. A standard gait cycle, with a twin-peak loading (2.5kN peak load and approximately 70N swing phase load), extension/flexion 15°/+30° and internal/external ±10° rotations, was applied. Translational mismatch in the medial-lateral axis between the
To determine the results critically of cementless third generation prosthesis (proximal fit, porous coated, and tapered distal stem), a prospective study was performed only in Charnley class A patients under 50 years of age who underwent primary total hip arthroplasty. 50 patients (50 hips) were included in study (37 were male and 13 were female). Average age of patients was 45.4 years (26–50 years). IPS(Immediate Postoperative Stability) stems (DePuy, Leeds, UK) were implanted in all hips. Cementless Duraloc cups (DePuy, warsaw, IN.) were used in all hips. 22 mm zirconia femoral head was used in all hips. All surgeries were performed by one surgeon (YHK). The redominant Dx. was osteonecrosis (30 hips or 60%), O.A. 2° to childhood T.B. or pyogenic arthritis (8 hips or 16%) and others (12 hips or 24%). The average F.U. was 6.3 years (5–7 years). Thigh pain was evaluated using a visual analog scale (10 points). Clinical (Harris hip score) and x-ray follow-up was performed at 6 weeks, 3 months, 6 months, 1 year and then annually. Linear and volumetric wear were measured by software program. Abductor moment arm, femoral offset, neck and limb length,
Aims. In patients with a rotator cuff tear, tear pattern and tendon involvement are known risk factors for the development of pseudoparalysis of the shoulder. It remains unclear, however, why similar tears often have very different functional consequences. The present study hypothesizes that individual shoulder anatomy, specifically the moment arms (MAs) of the rotator cuff (RC) and the deltoid muscle, as well as their relative recruitment during shoulder abduction, plays a central role in pseudoparalysis. Materials and Methods. Biomechanical and clinical analyses of the pseudoparalytic shoulder were conducted based on the ratio of the RC/deltoid MAs, which were used to define a novel anatomical descriptor called the Shoulder Abduction Moment (SAM) index. The SAM index is the ratio of the radii of two concentric spheres based on the
Reverse total shoulder arthroplasty (RTSA) is an increasingly common treatment for osteoarthritic shoulders with irreparable rotator cuff tears. Although very successful in alleviating pain and restoring some function there is little objective information relating geometric changes imposed by the reverse shoulder and the moment generating capacity of the shoulder muscles. Recent modeling studies of reverse shoulders have shown significant variation in deltoid muscle moment arms over varied joint centers for shoulders with RTSA. The goal of this study was to investigate the sensitivity of muscle moment arms as a function of varying the joint center in one representative RTSA subject. We hypothesized there may exist a more beneficial joint implant placement, measured by muscle moment arms, compared to the actual surgical implant placement. A 12 degree of freedom, subject-specific model was used to represent the shoulder of a patient with RTSA for whom fluoroscopic measurements of scapular and humeral kinematics during abduction had been obtained. The computer model used these abduction kinematics and systematically varied joint center locations over 1521 different perturbations from the surgical placement to determine moment arms for the anterior, lateral and posterior aspects of the deltoid muscle. The joint center was varied from its surgical position ±4 mm in the anterior/posterior direction, 0–24 mm in the medial/lateral direction, and −10 mm to 14 mm in the superior/inferior direction. The anterior deltoid moment arm varied up to 16mm with
Hemiarthroplasty is a common procedure that is an attractive alternative to total arthroplasty because it conserves natural tissue, allows for quicker recovery, and has a lower cost. One significant issue with hemiarthroplasties is that they lead to accelerated wear of the opposing native cartilage, likely due to the high stiffness of the implant. The purpose of this study was to investigate the range of currently available biomaterials for hemiarthroplasty applications. We employed a finite-element (FE) model of a radial head implant against the native capitellum as our joint model. The FE model was developed in ABAQUS v6.14 (Dassault Systèmes Simulia Corp., Providence, RI, USA). A solid axisymmetric concave implant with seven different materials and the native radial head were evaluated, six modelled as elastic materials with different Young's moduli (E) and Poisson's Ratios (ν), and one modelled as a Mooney-Rivlin hyperelastic material. The materials investigated were CoCr (E=230 GPa, ν = 0.3), PEEK (E=3.7 GPa, ν = 0.36), HDPE (E=2.7 GPa, ν = 0.42), UHMWPE (E=0.69 GPa, ν = 0.49), Bionate 75D (E=0.288 GPa, ν = 0.39), Bionate 55D (E=0.039 GPa, ν = 0.45), and Bionate 80A (modelled as a Mooney-Rivlin hyperelastic material). A load of 100 N was applied to the radius through the
Aims. It may not be possible to undertake revision total hip arthroplasty
(THA) in the presence of massive loss of acetabular bone stock using
standard cementless hemispherical acetabular components and metal
augments, as satisfactory stability cannot always be achieved. We
aimed to study the outcome using a reconstruction cage and a porous
metal augment in these patients. Patients and Methods. A total of 22 acetabular revisions in 19 patients were performed
using a combination of a reconstruction cage and porous metal augments.
The augments were used in place of structural allografts. The mean
age of the patients at the time of surgery was 70 years (27 to 85)
and the mean follow-up was 39 months (27 to 58). The mean number
of previous THAs was 1.9 (1 to 3). All patients had segmental defects
involving more than 50% of the acetabulum and seven hips had an
associated pelvic discontinuity. . Results. Three failures were observed in two hips, both of which had undergone
a previous resection of a tumour affecting the acetabulum. Other
complications included a late arterial injury, a sciatic nerve palsy,
a dislocation treated with a femoral revision, a deep infection
treated with irrigation and debridement and a fracture of the greater
trochanter treated conservatively. The mean Oxford Hip Score significantly
increased from 13.9 (2 to 23) to 28.7 (13 to 38) (p <
0.00001).
The mean vertical distance between the
Purpose of the study: Implanting a femoral stem with a modular neck can modify the range and the position in space of hip rotation arcs. The purpose of this work was to evaluate changes in three versions of a modular neck and to define the determining criteria for the choice of the neck to implant. Material and method: This series included 52 primary modular THA (ABGII) with ceramic bearings implanted with the HipNav 1.3 navigation system. The range of hip rotation were measured referring to the femoral saggital plane and the anterior pelvic plane. After insertion of the cup and the final ABGII stem and after choosing the length of the modular neck and the frontal inclination, the three different versions (retroversion −7, neutral 0 and anteverion +7) were tested. The range of hip rotation was measured by dynamic testing done under navigation. At the same time, the surgeon evaluated the stability and the absence of posterior impingement. Results: In extension, mean range of rotation was 71° (102–123). It was modified by neck version. The position of the
INTRODUCTION. Total hip arthroplasty (THA) is regarded as one of the most successful surgeries in medicine. However, recent studies have revealed that ideal acetabular cup implantation is achieved less frequently than previously thought, as little as 50% of the time. It is well known that malalignment of the acetabular component in THA may result in dislocation, reduced range of motion, or accelerated wear. This study reports accuracy of a tactile robotic arm system to ream the acetabulum and impact an acetabulur cup compared to manual instrumentation. METHODS. 12 fresh frozen cadaveric acetabulae were pre-operatively CT scanned and 3D templating was used to plan the
We evaluated the accuracy with which a custom-made
acetabular component could be positioned at revision arthroplasty
of the hip in patients with a Paprosky type 3 acetabular defect. A total of 16 patients with a Paprosky type 3 defect underwent
revision surgery using a custom-made trabecular titanium implant.
There were four men and 12 women with a median age of 67 years (48
to 79). The planned inclination (INCL), anteversion (AV), rotation
and
Introduction. It is well accepted that larger heads provide more stability in total hip arthroplasty. This is due to an increase in jump height providing increased resistance to subluxation. However, other implant parameters also contribute to the bearing's stability. Specifically, the liner's rim design and the
Aims: This study evaluates the clinical results of acetabular revision with Lima SPH Anatomic cup in 63 cases, performed at our Institute since 1999. Methods: We have evaluated 63 acetabular revision with SPH Anatomic cup in retrospective way. All the cases were produced by aseptic loosening and bone loss was in stage I or II according to GIR classiþcation (simple acetabular enlargement or one wall defect). The evaluation occurred after 1 to 3.5 years. Results: Preoperative mean Harris Hip Score was 54 and at time of evaluation it was 91. No sign of loosening was found. The mean cranial elevation of
Purpose. Crowe IV complete dislocated hips were thought to be difficult for primary THA. Correction for leg length discrepancy associated with nerve palsy or tough to reduction during surgery. Purpose of this study was to evaluate 3.5cm total leg length correction for any type of Crowe IV patients setting in anatomical positioning of acetabular cup with femoral shortening osteotomy. Materials & Methods. 24 hips were evaluated averaged 28 months after primary THA. Correction length of
The accurate reconstruction of hip anatomy and
biomechanics is thought to be important in achieveing good clinical
outcomes following total hip arthroplasty (THA). To this end some
newer hip designs have introduced further modularity into the design
of the femoral component such that neckshaft angle and anteversion,
which can be adjusted intra-operatively. The clinical effect of
this increased modularity is unknown. We have investigated the changes
in these anatomical parameters following conventional THA with a
prosthesis of predetermined neck–shaft angle and assessed the effect
of changes in the hip anatomy on clinical outcomes. . In total, 44 patients (mean age 65.3 years (standard deviation
(. sd. ) 7); 17 male/27 female; mean body mass index 26.9 (kg/m²)
(. sd. 3.1)) underwent a pre- and post-operative three-dimensional
CT scanning of the hip. The pre- and post-operative neck–shaft angle,
offset, hip
Surgical management of cam-type femoroacetabular impingement (FAI) aims to preserve the native hip, restore joint function, and delay the onset of osteoarthritis. However, it is unclear how surgery affects joint mechanics and hip joint stability. The aim was to examine the contributions of each surgical stage (i.e., intact cam hip, capsulotomy, cam resection, capsular repair) towards hip joint