Purpose. The ultimate goal in total hip arthroplasty is not only to relieve the pain but also to restore original hip joint biomechanics. The average femoral neck-shaft angle(FNSA) in Korean tend to have more varus pattern. Since most of conventional femoral stems have relatively high, single, fixed neck shaft angle, it's not easy to restore vertical and horizontal offset exactly especially in Korean people. This study demonstrates the advantages of dual offset(especially high-offset) stem for restoring original biomechanics of hip joint during the total hip arthroplasty in Korean. Materials and Methods. 180 hips of 155 patients who underwent total hip arthroplasty using one of the standard(132°) or extended(127°) offset Accolade cementless stems were evaluated retrospectively. Offset of stem was chosen according to the patient's own FNSA in preoperative templating. In a morphometric study, neck-shaft angle of proximal femur, vertical offset and horizontal offset, abductor moment arm were measured on preoperative and postoperative both hip AP radiographs and the differences and correlation of each parameters, between operated hip and original non-operated hip which had no deformity (preoperative ipsilateral or postoperative contralateral hip), were analyzed. Results. The standard stems were used in 34 hips and extended offset stems were used in 146 hips. The FNSA of non-operated hip was an average of 129.8°(127.2°□135.8°) in standard group and mean 125.4°(122.7°□129.9°) in extended offset group. The FNSA of operated hip was an average of 131.6° and 127.1° in each group. In the statistical analysis, there was no significant difference of mean horizontal and abductor moment arm between operated hip and non-operated hip in both groups and the restoration of horizontal offset and abductor moment arm showed(p=0.217, p=0.093) significant positive correlation(R=0.870, R=0.851) to the original value. However, vertical offset was increased an average of 1.4mm in operated hip and there was statistical significance. Restoration of vertical offset showed positive correlation to original value (R=0.845). Conclusion. Dual- or multi-offset stem, especially extended offset stem can provide easy restoration of hip biomechanics and soft tissue tension without significant alteration of leg length especially in Korean with more varus femoral neck compared to Caucacian. Precise radiographic measurements of original hip and application of proper-offset stem should be taken in order to restore ideal hip biomechanics successfully and easily. A use of a proper offset stem can afford to enhance joint stability and implant longevity by improving soft-tissue tension and reducing resultant force, and it will guarantee a successful results after total hip arthroplasty in the aspect of function and longevity

Introduction. The objective of our study was to determine the extent to which the quality of the biomechanical reconstruction when performing hip replacement influences gait performances. We aimed to answer the following questions: 1) Does the quality of restoration of hip biomechanics after conventional THR influence gait outcomes? (question 1), and 2) Is HR more beneficial to gait outcomes when compared with THR? (question 2). Methods. we retrospectively reviewed 52 satisfied unilateral prosthetic hip patients (40 THRs and 12 HRs) who undertook objective gait assessment at a mean follow-up of 14 months. The quality of the prosthetic hip biomechanical restoration was assessed on standing pelvic radiograph by comparison to the healthy contralateral hip. Results. We were unable to detect any statistically significant correlation between the radiographical parameters and the gait data, for THR patients. In stress conditions (inclination or declination of the ramp), the gait was more symmetric in the HR group, compared to the THR group. Discussion/Conclusions. We found that slight variations in the quality of the hip biomechanical restoration had little effect on gait outcomes of THR patients, and HR generated a more physiological gait under stress conditions than well-functioning THR

Introduction and Objective. A proper restoration of hip biomechanics is fundamental to achieve satisfactory outcomes after total hip arthroplasty (THA). A global hip offset (GO) postoperatively reduction of more than 5 mm was known to impair hip functionality after THA. This study aimed to verify the restoration of the GO radiographic parameter after primary THA by the use of a cementless femoral stem available in three different offset options without length changing. Materials and Methods. From a consecutive series of 201 patients (201 hips) underwent primary cementless THA in our centre with a minimum 3-year follow up, 80 patients (80 hips) were available for complete radiographic evaluation for GO and limb length (LL) and clinical evaluation with Harris hip score (HHS). All patients received the same femoral stem with three different offset options (option A with – 5 mm offset, option B and option C with + 5 mm offset, constant for each sizes) without changing stem length. Results. Mean GO significantly increased by + 3 mm (P < 0.05) and mean LL significantly decreased by + 5 mm (P < 0.05) after surgery, meaning that postoperatively the limb length of the operated side increased by + 5 mm. HHS significantly improved from 56.3 points preoperatively to 95.8 postoperatively (P < 0.001). Offset option A was used in 1 hip (1%), B in 59 hips (74%) and C in 20 hips (25%). Conclusions. The femur is lateralized with a mean of + 5mm after surgery than, the native anatomy, whatever type of stem was used. Thus, the use of this 3-offset options femoral stem is effective in restoring the native biomechanical hip parameters as GO, even if 2 offset options were considered sufficient to restore GO

Hip joint biomechanics can be altered by abnormal morphology of the acetabulum and/or femur. This may affect load distribution and contact stresses on the articular surfaces, hence, leading to damage and degradation of the tissue. Experimental hip joint simulators have been used to assess tribology of total hip replacements and recently methods further developed to assess the natural hip joint mechanics. The aim of this study was to evaluate articular surfaces of human cadaveric joints following prolonged experimental simulation under a standard gait cycle. Four cadaveric male right hips (mean age = 62 years) were dissected, the joint disarticulated and capsule removed. The acetabulum and femoral head were mounted in an anatomical hip simulator (Simulation Solutions, UK). A simplified twin peak gait cycle (peak load of 3kN) was applied. Hips were submerged in Ringers solution (0.04% sodium azide) and testing conducted at 1 Hertz for 32 hours (115,200 cycles). Soft tissue degradation was recorded using photogrammetry at intervals throughout testing. All four hips were successfully tested. Prior to simulation, two samples exhibited articular surface degradation and one had a minor scalpel cut and a small area of cartilage delamination. The pre-simulation damage got slightly worse as the simulation continued but no new areas of damage were detected upon inspection. The samples without surface degradation, showed no damage during testing and the labral sealing effect was more obvious in these samples. The fact that no new areas of damage were detected after long simulations, indicates that the loading conditions and positioning of the sample were appropriate, so the simulation can be used as a control to compare mechanical degradation of the natural hip when provoked abnormal conditions or labral tissue repairs are simulated

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 centre of hip rotation in patients undergoing conventional manual THA versus robotic-arm assisted THA. Secondary objectives were to determine differences between these treatment techniques for THA in achieving the planned combined offset, cup inclination, cup version, and leg-length correction. This prospective cohort study included 50 patients undergoing conventional manual THA and 25 patients receiving robotic-arm assisted THA. All operative procedures were undertaken by a single surgeon using the minimally-invasive posterior approach. Two independent blinded observers recoded all radiological outcomes of interest using plain radiographs. Patients in both treatment groups were well-matched for age, gender, body mass index, laterality of surgery, and ASA scores. Interclass correlation coefficient was 0.92 (95% CI: 0.84 – 0.95) for intra-observer agreement and 0.88 (95% CI: 0.82–0.94) for inter-observer agreement in all study outcomes. Robotic THA was associated with improved accuracy in restoring the native horizontal (p<0.001) and vertical (p<0.001) centres of rotation, and improved preservation of the patient's native combined offset (P<0.001) compared to conventional THA. Robotic THA improved accuracy in positioning of the acetabular cup within the combined safe zones of inclination and anteversion described by Lewinnek et al (p=0.02) and Callanan et al (p=0.01) compared to conventional THA (figures 1–2). There was no difference between the two treatment groups in achieving the planned leg-length correction (p=0.10). Robotic-arm assisted THA was associated with improved accuracy in restoring the native centre of rotation, better preservation of the combined offset, and more precise acetabular cup positioning within the safe zones of inclination and anteversion compared to conventional manual THA. Robotic-arm assisted THA enables improved preservation of native hip biomechanics compared to conventional manual THA. For any figures or tables, please contact authors directly: . fsh@fareshaddad.net

Introduction. Natural population variation in femoral morphology results in a large range of offsets, anteversion angles and lengths. During total hip arthroplasty, accurate restoration of hip biomechanics is essential to achieve good functional results. One option is to restore the anatomic hip rotation center. Alternatively, medializing the rotation center and compensating by increasing the femoral offset, reduces acetabular contact forces and increases the abductor lever arm. We investigated the ability of two cemented stem systems to restore hip biomechanics in an anatomic and medialized way. We compared an undersized “Exeter-type” of stem with three offset options and 18 sizes (CPT, Zimmer), to a line-to-line “Kerboul-type” of stem with proportional offset and 12 sizes (Centris, Mathys). Methods. Thirty CT scans of whole femora were segmented and the hip rotation center, proximal femoral axis and femoral length were determined with Mimics and 3-matic (Materialise). Using scripting functionality in the software, CAD design files of both stems were automatically sized and aligned along the proximal femoral axis to restore an anatomical and a 5 mm medialized hip rotation center. Stem size and position could be fine-tuned manually. The maximum distances between the prosthetic (PRC), the anatomic (ARC) and the medialized hip rotation center (MRC) were calculated (Fig. 1). Variations in femoral offset (ΔFO), anteroposterior (ΔAP) and proximodistal distance (ΔPD) were analyzed. Finally, the number of cases where the hip rotation center could be restored within 5 mm was reported. Results. Both implants allowed restoring the ARC accurately (mean distance PRC-ARC: CPT 0.97±0.88 mm, Centris 1.66±1.59 mm; mean difference ΔFO: CPT 0.09±0.19 mm, Centris 0.11±0.29 mm; mean difference ΔAP: CPT 0.12±1.22°, Centris 0.27±1.78 mm, mean difference ΔPD: CPT 0.04±0.44 mm, Centris 0.49±1.35 mm). The CPT stem allowed restoring the PRC within 5 mm of the ARC in all cases (max. 4.31 mm), whereas the Centris stem achieved this in only 28/30 hips (max. 6.72 mm) (Fig. 2). Aiming for a MRC was less satisfactory with both stems (mean distance PRC-MRC: CPT 1.38±1.63 mm, Centris 3.61±2.73 mm; mean difference ΔFO: CPT 0.09±0.10 mm, Centris 0.06±0.35 mm; mean difference ΔAP: CPT 0.17±2.02 mm, Centris 2.58±2.68 mm, mean difference ΔDP; CPT 0.28±0.67 mm, Centris 1.98±1.66 mm). The CPT stem allowed restoring the PRC within 5 mm of the MRC in 29/30 cases (max. 8.09 mm), whereas the Centris stem achieved this in only 25/30 cases (max. 11.15 mm) (Fig. 3). Discussion. Although both stem systems allowed restoring hip biomechanics accurately in most cases, the CPT system was superior to the Centris stem for achieving both ARC and MRC. This could be explained by more implant sizes (18 vs. 12) and undersized stems offering more freedom to correct version. Although medializing the hip rotation center offers biomechanical advantages, both stems had more difficulties achieving this. In some cases, differences between aimed and planned rotation centers were close to 1 cm which might negatively impact on clinical outcome. As such, to avoid suboptimal reconstructions with the available implants, templating is mandatory especially when aiming at a medialized reconstruction strategy

Restoring native hip biomechanics is crucial to the success of THA. This is reflected both in terms of complications after surgery such as instability, leg length inequality, pain and limp; and in terms of patient satisfaction. The challenge that remains is that of achieving optimal implant sizing and positioning so as to restore, as closely as possible, the native hip biomechanics specific to the hip joint being replaced. This would optimise function and reduce complications, particularly, instability. (Mirza et al., 2010). Ideally, this skill should also be reproducible irrespective of the surgeon's experience, volume of surgery and learning curve. The general consensus is that the most substantial limiting factor in a THA is the surgeon's performance and as a result, human errors and unintended complications are not completely avoidable (Tarwala and Dorr, 2011). The more challenging aspects include acetabular component version, sizing and femoral component sizing, offset and position in the femoral canal. This variability has led to interest in technologies for planning THA, and technologies that help in the execution of the procedure. Advances in surgical technology have led to the development of computer navigation and robotic systems, which assist in pre-operative planning and optimise intra-operative implant positioning. The evolution of surgical technology in lower limb arthroplasty has led to the development of computer navigation and robotics, which are designed to minimise human error and improve implant positioning compared to pre-operative templating using plain radiographs. It is now possible to use pre-operative computerised tomography (image-based navigation) and/or anatomical landmarks (non-imaged-based navigation) to create three-dimensional images of each patient's unique anatomy. These reconstructions are then used to guide bone resection, implant positioning and lower limb alignment. The second-generation RIO Robotic Arm Interactive Orthopaedic system (MAKO Surgical) uses pre-operative computerised tomography to build a computer-aided design (CAD) model of the patient's hip. The surgeon can then plan and execute optimal sizing and positioning of the prostheses to achieve the required bone coverage, minimise bone resection, restore joint anatomy and restore lower limb biomechanics. The MAKO robotic software processes this information to calculate the volume of bone requiring resection and creates a three-dimensional haptic window for the RIO-robotic arm to resect. The RIO-robotic arm has tactile and audio feedback to resect bone to a high degree of accuracy and preserve as much bone stock as possible. We have used this technology in the hip to accurately reproduce the anteversion, closure and center of rotation that was planned for each hip. Whilst the precise safe target varies from patient to patient, the ability to reproduce native biomechanics, to gain fixation as planned and to get almost perfect length and offset are a great advantage. Complications such as instability and leg length inequality are thus dramatically reduced

The literature indicates that femoroacetabular impingement (FAI) patients do not return to the level of controls (CTRL) following surgery. The purpose of this study was to compare hip biomechanics during stair climbing tasks in FAI patients before and two years after undergoing corrective surgery against healthy controls (CTRL). A total of 27 participants were included in this study. All participants underwent CT imaging at the local hospital, followed by three-dimensional motion analysis done at the human motion biomechanics laboratory at the local university. Participants who presented a cam deformity >50.5° in the oblique-axial or >60° in the radial planes, respectively, and who had a positive impingement test were placed in the FAI group (n=11, age=34.1±7.4 years, BMI=25.4±2.7 kg/m2). The remaining participants had no cam deformity and negative impingement test and were placed in the CTRL group (n=16, age=33.2±6.4 years, BMI=26.3±3.2 kg/m2). The CTRL group completed the biomechanics protocol once, whereas the FAI group completed the protocol twice, once prior to undergoing corrective surgery for the cam FAI, and the second time at approximately two years following surgery. At the human motion biomechanics laboratory, participants were outfitted with 45 retroreflective markers placed according to the UOMAM marker set. Participants completed five trials of stairs task on a three step instrumented stair case to measure ground reaction forces while 10 Vicon MX-13 cameras recorded the marker trajectories. Data was processed using Nexus software and divided into stair ascent and stair descent tasks. The trials were imported into custom written MatLab software to extract peak pelvis and hip kinematics and hip kinetic variables. Non-parametric Kruskal-Wallis tests were used to determine significant (p < 0.05) differences between the groups. No significant differences occurred during the stair descent task between any of the groups. During the stair ascent task, the CTRL group had significantly greater peak hip flexion angle (Pre-Op=58±7.1°, Post-Op=58.1±6.6°, CTRL=64.1±5.1°) and sagittal hip range of motion (ROM) (Pre-Op=56.7±6.7°, Post-Op=56.3±5.5°, CTRL=61.7±4.2°) than both the pre- and post-operative groups. Pre-operatively, the FAI group had significantly less peak hip adduction angle (Pre-Op=2±4.5°, Post-Op=3.4±4.4°, CTRL=5.5±3.7°) and hip frontal ROM (Pre-Op=9.9±3.4°, Post-Op=11.9±5.4°, CTRL=13.4±2.5°) compared to the CTRL group. No significant differences occurred in the kinetic variables. Our findings are in line with the Rylander and colleagues (2013) who also found that hip sagittal ROM did not improve following corrective surgery. Their study included a mix of cam and pincer-type FAI, and had a mean follow-up of approximately one year. Our cohort included only cam FAI and they had a mean follow-up of approximately two years, indicating with the extra year, the patients still did not show sagittal hip kinematics improvement. In the frontal plane, there was no significant difference between the post-op and the CTRL, indicating that the postoperative FAI reached the level of the CTRLs. This is in line with recent work that indicates a more medialized hip contact force vector following surgery, suggesting better hip stabilization

Introduction. Golf is a recommended form of physical activity for older adults. However, clinicians have no evidence-based research regarding the demands on the hips of older adults during golf. The purpose of our in vivoobservational study was to quantify the hip biomechanics of older adult golfers. Methods. Seventeen healthy older male golfers(62.2±8.8 years, handicap 8.7±4.9) free from orthopaedic injuries and surgeries volunteered for participation in this IRB-approved study. A 10-camera motion capture system recorded kinematics, and two force plates collected kinetic data. Participants performed eight shots using their own driver. Data processing was performed in Visual3D. The overall range of excursion and three-dimensional net joint moments normalized to body weight for the lead and trail hips were extracted. Results. Kinematics (mean excursion and range) of lead and trail hips in all three planes during a golf swing are presented in Table 1. The trail leg experiences higher excursion in the sagittal plane, while the lead leg has more frontal plane movement. Average maximum net joint moments of the lead and trail hips were 1.2 ± 0.2 and 1.7 ± 0.3 Nm/kg, respectively. Conclusion. Our study is the first to quantify the kinematics and kinetics of the hip joint in healthy older male golfers. While the golf swing is often considered to be a predominant transverse plane motion, our results indicate considerable excursion at the hip joints in all three planes. Furthermore, the trail leg experiences 40% greater loading than the lead leg throughout the swing, suggesting that the trail leg may have a larger impact on golf performance while also leaving it more susceptible to overuse injury. For clinicians with patients who experience osteoarthritis of the hip or who have recently undergone hip surgery, this study may provide novel insight into the demands of golf on the hips. For any tables or figures, please contact the authors directly

Over the past 15 years Anterior Approach (AA) THA has shown a dramatic increase in adoption by surgeons (over 30%) and choice by patients with a corresponding decrease in the percentage of hips performed with traditional posterior and lateral approaches. I began AA in 1996 in order to solve the classic problems of potential dislocation associated with posterior approach and potential abductor weakness associated with the lateral (Harding) approach. Surgeon education on AA began in 2013 and has accelerated since. AA is usually performed with the aid of an orthopaedic table which facilitates exposure though many cases are also performed on a standard operating table. Intraoperative image intensification has provided real-time feedback and accuracy for cup position leg length and offset and is facilitated by the supine position and a radiolucent orthopaedic table, however, AA can be performed without it. Earlier functional recovery with decreased post-operative pain is the best documented benefit of AA as well as decreased dislocation rate. My own point of view is to take advantage of a switch to AA to improve more than your surgical approach. Improve also hip biomechanics, cup position, ease of surgery, bone preparation, and soft tissue handling. A proven and repeatable technique and use of available technologies will facilitate this

Background. Modularity in total hip replacement(THR) enables precise recreation of native hip biomechanics. However, there have been concerns about raised metal ion levels with increased number of interfaces. We present the 3 year results of ML taper with Kinectiv technology(MLKT), a modular neck uncemented stem. This system has modular neck options, but has only one [0] head in various diameters. Methods. 97 hips in 97 patients with a MLKT stem and Continuum socket were included in this prospective study. Harris hip score, Oxford hip scores (HHS and OHS) and yearly blood Cobalt(Co), Chromium(Cr) and Titanium(Ti) were recorded. The primary end point was revision for any reason. Paired t- test was used to assess improvement in functional scores. Results. The mean age was 62.1±8.7 years. The mean follow-up was 3.75±0.67years. The mean HHS improved from 45.8±5.1 to 92.6±3.1(p<0.001) and the mean OHS improved form 17.59±4.71 to 43.1±2.2(p<0.001). One hip was revised for deep infection at 2.6 years. The mean Co, Cr and Ti levels at 3 years were 18.45,19.62 and 36.47 nmol/l respectively. The survivorship of the cohort at a minimum follow-up of 3 years was 98.7%. Conclusion. Our study suggests that despite the presence of an additional interface between the neck and the stem, the MLKT stem does not result in increased metal ion levels or higher failure rate. This is a prospective and consecutive series of patients with complete radiological and functional follow-up. The MLKT stem has good functional results with no concerns about raised metal ion levels in the short term

INTRODUCTION. Combining novel diverse population-based software with a clinically-demonstrated implant design is redefining total hip arthroplasty. This contemporary stem design utilized a large patient database of high-resolution CT bone scans in order to determine the appropriate femoral head centers and neck lengths to assist in the recreation of natural head offset, designed to restore biomechanics. There are limited studies evaluating how radiographic software utilizing reference template bone can reconstruct patient composition in a model. The purpose of this study was to examine whether the application of a modern analytics system utilizing 3D modeling technology in the development of a primary stem was successful in restoring patient biomechanics, specifically with regards to femoral offset (FO) and leg length discrepancy (LLD). METHODS. Two hundred fifty six patients in a non-randomized, post-market multicenter study across 7 sites received a primary cementless fit and fill stem. Full anteroposterior pelvis and Lauenstein cross-table lateral x-rays were collected preoperatively and at 6-weeks postoperative. Radiographic parameters including contralateral and operative FO and LLD were measured. Preoperative and postoperative FO and LLD of the operative hip were compared to the normal, native hip. Clinical outcomes including the Harris Hip Score (HHS), Lower Extremity Activity Scale (LEAS), Short Form 12 (SF12), and EuroQol 5D Score (EQ-5D) were collected preoperatively, 6 weeks postoperatively, and at 1 year. RESULTS. The mean age is 62 years old (range 32 – 75), 136 male and 120 female, BMI 29.7. The preoperative FO and LLD of the operative hip were 43.5 mm (±9.0 mm) and 3.0 mm (±6.5 mm) compared to the native contralateral hip, respectively. The postoperative FO and LLD were 46.4 mm (±8.7 mm) and 1.6 mm (±7.6 mm) compared to the native contralateral hip, respectively. The change in FO on the operative side was 3.0 mm (±7.2 mm) (p<0.0001) and the change in LLD from preoperative to 6-weeks postoperative was 1.6 mm (±8.4 mm) (p=0.0052) (Figure 1), demonstrating the ability of this stem design to recreate normal hip biomechanics in this study. The HHS increased considerably from a preoperative score of 55.9 to 78.4 at 6 weeks and 92.7 at 1 year. Clinically significant improvements were also seen at 1 year in the LEAS (+2.3), SF12 PCS (+16.3), and EQ-5D TTO (+0.26) and the EQ-5D VAS (+15.7). DISCUSSION and CONCLUSION. This study demonstrated that recreation of normal anatomic leg length and offset is possible by utilizing a modern fit and fill stem that was designed by employing an advanced anthropomorphic database of CT scans. We hypothesize that when surgeons utilize this current fit and fill stem design, it will allow them to accurately recreate a patient's natural FO and leg length, assisting in the restoration of patient biomechanics. Summary Sentence. In this study, modern design methods of a press-fit stem using 3D modeling tools recreated natural femoral offset and leg length, assisting in the restoration of patient biomechanics

There are a growing number of younger patients with developmental dysplasia of hip, proximal femoral deformity and osteonecrosis seeking surgical intervention to restore quality of life, and the advent of ISTCs has resulted in a greater proportion of such cases being referred to existing NHS departments. Bone-saving hip athroplasty is often advocated for younger active patients, as they are potential candidates for subsequent revision arthroplasty. If resurfacing is contraindicated, short bone-conserving stems may be an option. The rationale for short stems in cementless total hip arthroplasty is proximal load transfer and absence of distal fixation, resulting in preserved femoral bone stock and avoidance of thigh pain. We have carried out 17 short stem hip replacements (Mini-hip, Corin Medical, Cirencester, UK) using ceramic bearings in 16 patients since June 2010. There were 14 females and 2 males, with a mean age of 50.1 years (range 35–63 years) at the time of the surgery. The etiology was osteoarthritis in 11, developmental dysplasia in 4, and osteonecrosis of the femoral head in one patient. All operations were performed through a conservative anterolateral (Bauer) approach. These patients are being followed and evaluated clinically with the Harris and Oxford hip scores, with follow-up at 6 weeks, 3 months, and annually thereafter. Initital results have been encouraging in terms of pain relief, restoration of leg length (one of the objectives in cases of shortening) and rage of movement. Radiological assessment has shown restoration of hip biomechanics. Specific techniques are required to address varus, valgus and femoral deformity with leg length inequality. There are two main groups of short stems, those that are neck-preserving and those that do not preserve the femoral neck. The latter group requires traditional techniques for revision. Another feature that differentiates them is the availability of modularity. The device we employed is neck-preserving and available with different neck lengths and offsets, which help in restoration of hip biomechanics. The advantage of such short stems may be preservation of proximal femoral bone stock, decreased stress shielding and the ease of potential revision. Such devices may be a consideration for patients with malformations of the proximal femur. Long-term follow-up will be of value in determining if perceived benefits are realised in practice

The anterior approach is now an accepted approach for total hip arthroplasty. First described over a century ago, its popularity has grown significantly in the last decade with the advent of a reproducible technique on an orthopaedic table. Potential advantages include quicker recovery times, less post-operative pain, improved hip biomechanics, and more accurate cup position. While both femoral exposure and learning curve are often cited as potential drawbacks, a large percentage of US surgeons now utilise this teachable approach. The adoption of this approach has facilitated the development of new tools to assist the arthroplasty surgeon in a more efficient and efficacious manner. The anterior approach is performed with the patient in a supine position on an orthopaedic table. The supine position provides improved visualization of the acetabulum, appreciation of pelvic position as well as the advantage of intra-operative fluoroscopy. While many technologies including navigation and first generation robotics exist to assist the surgeon with virtual information; only fluoroscopy provides the surgeon with real time actual information. The interpretation of fluoroscopic images carries a learning curve and potential for error. New technology now exists to assist the surgeon to better interpret fluoroscopic images including anteversion and abduction of cup, leg length and offset. Since the first hip surgery was performed by Sir John Charnley, hip surgeons have utilised specialised tools including reamers, drills, saws, and mallets during surgery to assist with cup insertion, femoral preparation, stem insertion, liner insertion and head impaction. Many tools in the operating room including drills, reamers, and saws have moved from hand powered operation to pneumatic and now battery powered operation to assist with efficiency, efficacy, and reduced surgeon fatigue. A new, battery powered impaction device provides a consistent and constant energy that does not rely on the surgeon's mallet speed, throw distance, or impact contact. This may represent the next generation of surgical tools available to the arthroplasty surgeon that has the potential to make the mallet obsolete

Introduction: The goal is to avoid letting femoral deformity force suboptimal implant position/fixation. Suboptimal implant position has an adverse effect on hip biomechanics and often on hip function and durability. Classification: Practical approach to femoral deformities: categorise into 3 main groups: Very proximal, Subtrochanteric, Distal. Management: Management of distal deformities: Most can be ignored if there is sufficient room to place conventional femoral implant. Management of proximal deformities: Option 1: Use implants that allow satisfactory positioning despite deformity…or… Option 2: Remove the deformity. Management of subtrochanteric level deformities: These are the most difficult. Problems: Too proximal to ignore, Too distal to bypass. Main treatment options: Resurfacing THA, Short stem THA, Corrective osteotomy with THA. Corrective osteotomy with THA: Perform osteotomy at level of deformity, In most cases a corrective osteotomy that creates a transverse osteotomy junction is simplest, Use an implant that provides reliable fixation in the femur (usually uncemented), Use implant that provides fixation of the proximal and distal fragments. Conclusions: Majority of proximal femoral deformities managed with one-stage procedure: Excise deformity and replace with metal, Implants that allow ignoring deformity, Corrective osteotomy

Since the advent of total hip arthroplasty (THA), there have been many changes in implant design that have been implemented in an effort to improve the outcome of the procedure and enhance the surgeon's ability to reproducibly perform the procedure. Some of these design features have not stood the test of time. However, the introduction of femoral stem head/neck modularity made possible by the Morse taper has now been a mainstay design feature for over two decades. Modularity at the head-neck junction facilitates intraoperative adjustments. ‘Dual Taper’ modular stems in total hip arthroplasty have interchangeable modular necks with additional modularity at the neck and stem junction. This ‘dual taper’ modular femoral stem design facilitates adjustments of the leg length, the femoral neck version and the offset independent of femoral fixation. This has the potential advantage of optimizing hip biomechanical parameters by accurately reproducing the center of rotation of the hip. More recently, however, there is increasing concern regarding the occurrence of adverse local tissue reactions in patients with taper corrosion, which is emerging as an important reason for failure requiring revision surgery. Although adverse tissue reactions or ‘pseudotumor’ were initially described as a complication of metal-on-metal (MoM) bearings, the presence of pseudotumor in patients with taper corrosion is thought to result from corrosion at the neck-stem taper junction, secondary to reciprocating movement at the modular junction leading to fretting corrosion in a process described as mechanically assisted crevice corrosion (MACC). Therefore, the focus of this presentation is to summarise clinical challenges in diagnosis and treatment of patients with adverse tissue reactions due to taper corrosion and review up-to-date evidence

Modular total hip arthroplasty (MTHA) stems were introduced in order to provide increased intra-operative flexibility for restoring hip biomechanics, improving stability and potentially reducing revision risk. However, the additional interface at the neck-body junction provides another location for corrosion or mechanical failure of the stem. To delineate the mid term revision risk of MTHA stems, we examined data from the Canadian Joint Replacement Registry (CJRR) at the Canadian Institute for Health Information (CIHI). Kinectiv, Profemur and Rejuvenate modular stems were identified from CJRR records submitted between 2004 and 2014. Revision status was determined by examining the discharge abstract database (DAD) also housed by CIHI, which collects information on all revisions, regardless of whether the procedure was submitted to CJRR. A total of 2446 modular stems were identified with a mean follow up of 4.2 years (range 0 to 10). Their usage peaked in 2012 (the first year of mandatory CJRR form submission for BC, ON and MB), and dropped rapidly thereafter. A total of 155 (6.3%) were revised. This consisted of 5/301 Kinectiv (1.7%), 141/2050 ProFemur (6.9%), and 9/96 Rejuvenate (9.4%) stems. As a group, this falls below the National Institute for Clinical Excellence (NICE) guidelines of 95% survival at 10 years. While MTHA stems were introduced to improve outcomes and reduce revision risk, our findings of a 6.3% revision risk at a mean follow up of 4.2 years does not appear to support this

Many factors can negatively impact acetabular component positioning including poor visualization, increased patient size, inaccuracies of mechanical guides, and inconsistent precision of conventional instruments and techniques, and changes in patient positioning. Improper orientation contributes to increased dislocation rates, leg length discrepancies, altered hip biomechanics, component impingement, acetabular component migration, bearing surface wear, and pelvic osteolysis thus affecting revision rates and long-term survivorship. Despite the established definitions of acetabular safe zones, recent analysis of U.S. Medicare THA data found dislocation rates during the first six months to be 3.9% for primary surgeries and 14.4% for revision surgeries. Accurate and precise acetabular component orientation during initial THA is an increasingly important factor in decreasing revision THA; a recent report cites instability and dislocation as the primary cause of revision accounting for 22.5% of cases. Larger femoral heads and alternative bearing couples are less tolerant of variation in acetabular orientation and thus are poor substitutes for proper acetabular component placement. Variability in acetabular orientation has been reported to have both an inter-surgeon and an intra-surgeon component; pre-surgical templating combined with intraop-erative measurements is subject to inconsistencies and errors. Current methods for determining acetabular orientation include preoperative imaging such as CT scans, intraoperative imaging such as plain radiographs and fluoroscopy, and intraoperative anatomical tests. Combining the concepts of patient-specific morphology (PSM) and quantitative technologies (QuanTech) such as computer-assisted navigation (CAN) has the potential to maximise range of motion and to further improve acetabular component orientation through improved accuracy and precision. PSM refers to the practice of allowing the form and structure of the patient’s hip joint to guide surgical reconstruction and component placement thus creating an individualised and more accurate “target zone”; unlike “safe zones,” PSM does not rely on averages. Although gross anatomic changes may make it difficult to use PSM, certain structures may be used as guide-posts for orientation, alignment, and stability in most patients. At present, there are three options when considering anatomic landmarks as guides for acetabular component placement: bony landmarks, soft tissue landmarks, or a combination. QuanTech has been shown to increase the precision of component placement by reducing intra-surgeon deviation. Some pitfalls of current CAN techniques result from maintaining camera line of sight during surgery, registration process, and pin placement. Performing THA using smaller incisions can impose additional complications as well as risks for errors in component positioning; QuanTech has the potential to provide greater visualization and precision, thus decreasing the impact of those constraints. THA has become one of the most common and successful orthopaedic procedures; its efficacy at relieving pain and its ability to help patients have improved quality of life is without dispute yet results continue to vary with inter-surgeon and intra-surgeon differences. As the population needing THA increases, the prevalence of complications and problems will increase, even if the percentage of complications decreases. Coupling PSM with QuanTech such as CAN may allow the surgeon to decrease variability and more consistently implant THA components based on each patient’s individualized requirements. The goal of combining PSM and CAN is to further reduce inter-and intra-surgeon variation, thereby decreasing outliers, complications, and revision rates, and possibly narrowing the gap between specialist and generalist. More accurate and precise acetabular component orientation correlates with better hip biomechanics, translating into better function, fewer dislocations, fewer impingements, maximized safe range of motion, less wear, and therefore less aseptic loosening and improvements in survivorship of primary THA. Decreasing revision rates, combined with the benefits listed above, could translate into increased THA survivorship, improved patient satisfaction, and decreased economic burden on the entire healthcare system

Purpose. This studyevaluated the results of the acetabular medial wall osteotomy to reconstruct the acetabulum in dysplastic hip during total hip athroplasty. Materials and Methods. A total of 30 hips of 30 patients who underwent THA between March 1999 and October 2002 were clinically and radiogically evaluated. The average age at the time of operation was 46.5 years (range: 17 to 73 years), and the mean follow-up period was 5 years (range: 5.3 to 8.7 years). 26 cases, a cementless hemispherical acetabular cup and 4 cases, reinforced ring were inserted in the true acetabulum. Only 2 hips needed structural bone graft. Results. The average Harris hip score improved from 56.3 points preoperatively to 93.2 points at the last follow up. Radiographic analysis revealed no aseptic loosening or radiolucent line, and showed stable bony fixation at the true acetabulum. The mean thickness of the medial acetabular wall postoperative was 20.5 mm. Bone union of the medial wall observed at a mean of four months post-operatively. Conclusion. The acetabular medial wall osteotomy can provide the integrity of acetabular medial wall while achieving enhanced acetabular coverage and more normal hip biomechanics

The goal is to avoid letting femoral deformity force suboptimal implant position/fixation. Suboptimal implant position has an adverse effect on hip biomechanics and often on hip function and durability. Classification - Practical approach to femoral deformities: categorise into 3 main groups: 1.) Very proximal, 2.) Subtrochanteric, 3.) Distal. Management of distal deformities: Most can be ignored if there is sufficient room to place conventional femoral implant. Management of proximal deformities: Option 1: Use implants that allow satisfactory positioning despite deformity…or… Option 2: Remove the deformity. Management of subtrochanteric level deformities: These are the most difficult. Problems: 1.) Too proximal to ignore, 2.) Too distal to bypass. Main treatment options: 1.) Resurfacing THA, 2.) Short stem THA, 3.) Corrective osteotomy with THA. Corrective osteotomy with THA: 1.) Perform osteotomy at level of deformity, 2.) In most cases a corrective osteotomy that creates a transverse osteotomy junction is simplest, 3.) Use an implant that provides reliable fixation in the femur (usually uncemented), 4.) Use implant that provides fixation of the proximal and distal fragments. Majority of proximal femoral deformities managed with one-stage procedure: 1.) Excise deformity and replace with metal, 2.) Implants that allow ignoring deformity, 3.) Corrective osteotomy