Background. Variability in component alignment continues to be a major in total knee arthroplasty(TKA). In the long term, coronal plane malalignment has been associated with an increased risk of loosening, insatability, and wear. Recently portable navigation system(PNS) in TKA have been introduced. The goal of PNS are to improve the accuracy of post operative alignment and eliminate outlier cases. The aim of this study is to evaluate clinical results and quantify the coronal plane alignment between a group of patients who underwent TKA using PNS versus CT-free large-console navigation system. Patients and Method. An unselected consecutive series of ninety-four patients undergoing primary TKA using the cruciate retaining cemented total knee system between April 2012 and August 2015 were studied. Patients were included only if they were deemed to be candidates for a Cruciate retaining TKA. Patients were excluded if they had a flexion contracture greater than 40°, or severe valgus or varus deformity. Forty eight knees was operated a TKA with CT-free large-console navigation system(The OrthoPilot system; Aesculap, Tuttlingen, Germany). Subsequently forty six knees was received a TKA using portable navigation system (KneeAlign2. TM. ). Postoperatively standing AP hip-to-ankle radiographs were obtained, from which the lower extremity mechanical axis, component angle were measured. The alignment goals were a neutral mechanical axis defined as a hip-to-ankle angle of 0°with the femoral and tibial components aligned perpendicular to the mechanical axis. The total operating time were quantified utilising an operating room database. The total operating time between TKAs performed with CT-free navigation system and those performed with portable navigation system was compared in each group. All patients postoperatively was evaluated of clinical results the Japan Orthopedics Association(JOA) Knee scores. Results. The mechanical axis angle in PNS group was 0.8°, while the CT-free navigation system group was 1.6°and there was no statistical significance. The number of outliers for mechanical axis angle was PNS group 39.1%, the large-console navigation group 22.9%, between the two groups there was statistical significance. The operative time in PNS was 130.0 minutes and significantly less compared to the time of the large-console group 150.4 minutes. The JOA Knee score of navigation group was 83.9 points, and the score of PNS group was 81.0 points., there was no statistical significance between the two groups on the clinical score. Conclusion. portable navigation system improved operative time in TKA, this study demonstrates portable navigation system to obtain same angle of overall mechanical axis angle as large-console group navigation system

INTRODUCTION. The restoration of physiological kinematics is one of the goals of a total knee arthroplasty (TKA). Navigation systems have been developed to allow an accurate and precise placement of the implants. But its application to the intraoperative measurement of knee kinematics has not been validated. The hypothesis of this study was that the measurement of the knee axis, femoral rotation, femoral translation with respect to the tibia, and medial and lateral femorotibial gaps during continuous passive knee flexion by the navigation system would be different from that by fluoroscopy taken as reference. MATERIAL – METHODS. Five pairs of knees of preserved specimens were used. The e.Motion FP ® TKA (B-Braun Aesculap, Tuttlingen, Germany) was implanted using the OrthoPilot TKA 4.3 version and Kobe version navigation system (B-Braun Aesculap, Tuttlingen, Germany). Kinematic recording by the navigation system was performed simultaneously with fluoroscopic recording during a continuous passive flexion-extension movement of the prosthetic knee. Kinematic parameters were extracted from the fluoroscopic recordings by image processing using JointTrack Auto ® software (University of Florida, Gainesville, USA). The main criteria were the axis of the knee measured by the angle between the center of the femoral head, the center of the knee and the center of the ankle (HKA), femoral rotation, femoral translation with respect to the tibia, and medial and lateral femorotibial gaps. The data analysis was performed by a Kappa correlation test. The agreement of the measurements was assessed using the intraclass correlation coefficient (ICC) and its 95% confidence interval. RESULTS. The respective CCIs were as follows: HKA angle 0.839 [0.820; 0.856]; femoral translation 0.560 [0.517; 0.600]; femoral rotation 0.652 [0.616; 0.686]; medial femorotibial gap 0.905 [0.894; 0.916]; lateral femorotibial gap 0.767 [0.740; 0.791]. DISCUSSION. Measurements of TKA kinematics by the navigation system and by fluoroscopy were consistent for HKA angle and medial and lateral femorotibial gaps, but not for femoral translation and femoral rotation. These differences can be explained by a methodological bias. At the end of this work, the specific navigation system cannot be considered as a reliable instrument for measuring the kinematics of a TKA

The object of this study was to develop a method to assess the accuracy of an image-free total knee replacement navigation system in legs with normal or abnormal mechanical axes. A phantom leg was constructed with simulated hip and knee joints and provided a means to locate the centre of the ankle joint. Additional joints located at the midshaft of the tibia and femur allowed deformation in the flexion/extension, varus/valgus and rotational planes. Using a digital caliper unit to measure the coordinates precisely, a software program was developed to convert these local coordinates into a determination of actual leg alignment. At specific points in the procedure, information was compared between the digital caliper measurements and the image-free navigation system. Repeated serial measurements were undertaken. In the setting of normal alignment the mean error of the system was within 0.5°. In the setting of abnormal plane alignment in both the femur and the tibia, the error was within 1°. This is the first study designed to assess the accuracy of a clinically-validated navigation system. It demonstrates in vitro accuracy of the image-free navigation system in both normal and abnormal leg alignment settings

Total hip arthroplasty (THA) is an effective treatment for symptomatic hip osteoarthritis (OA). While computer-navigation technologies in total knee arthroplasty show survivorship advantages and are widely used, comparable applications within THA show far lower utilisation. Using national registry data, this study compared patient reported outcome measures (PROMs) in patients who underwent THA with and without computer navigation. Data from Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) PROMs program included all primary THA procedures performed for OA up to 31 December 2020. Procedures using the Intellijoint HIP® navigation system were identified and compared to procedures using other computer navigation systems or conventional instrumentation only. Changes in PROM scores between pre-operative and 6-month post-operative time points were analysed using multiple regression model, adjusting for pre-operative score, patient age, gender, ASA score, BMI, surgical approach, and hospital type. There were 65 primary THA procedures that used the Intellijoint HIP® system, 90 procedures used other types of computer navigation, and the remaining 5,284 primary THA procedures used conventional instrumentation. The estimated mean changes in the EuroQol visual analogue scale (EQ VAS) score and Oxford Hip score did not differ significantly when Intellijoint® was compared to conventional instruments (estimated differences of 2.4, 95% CI [-1.7, 6.5], p = 0.245, and −0.5, 95% CI [-2.5, 1.4], p = 0.592, respectively). The proportion of patients who were satisfied with their procedure was also similar when Intellijoint® was compared to conventional instruments (rate ratio 1.06, 95% CI [0.97, 1.16], p = 0.227). The preliminary data demonstrate no significant difference in PROMs when comparing the Intellijoint HIP® THA navigation system with both other navigation systems and conventional instrumentation for primary THAs performed for OA. Level of evidence: III (National registry analysis)

INTRODUCTION. Cup orientation of total hip arthroplasty (THA) is critical for dislocation, range of motion, polyethylene wear, pelvic osteolysis, and component migration. But, substantial error under manual technique has been reported specially in revision THA due to a bone loss and poor anatomical landmark. We have used three kinds of navigation systems for cup positioning in primary and revision THA. OBJECTIVES. The purpose of this study is to evaluate the accuracy of navigation in revision THAs. METHODS. Since 2005, consecutive 24 revision THAs were performed with volumetric post-operative CT scan images to measure three dimensional positionings of cups. We implanted cementless hemispherical cups in 14 hips using fluoro-based navigation (FN) system (Stealth Station Tria), in 5 hips using a CT-based navigation (CTN) system (VectorVision CT Hip 3.1) and in 5 hips using fluoro-CT-based navigation (FCTN) system (VectorVision CT Hip 3.5). For all the patients, volumetric post-operative CT scan was performed to measure 3D cup orientation. Using 3D image-processing software (JMM, Japan) we converted all data to radiographic angles to compare different navigation system. RESULTS. The difference from target angles of anteversion was 5.6 ± 4.9 degrees. The absolute value of difference from target angles of inclination was 6.5 ± 3.8 degrees. The system accuracy was 4.2±2.9 in inclination and 4.7 ± 4.1. Accuracy of three navigation system was not significantly different. No postoperative dislocation was observed in this series. No complication related to navigation system was observed, either. CONCLUSION. Cup malpositioning can easily occur with a conventional aligment guide especially in MIS THA due to complexity of a operation. In revision THAs, high incidence of malpositioning of cups and post operative dislocation were reported. We previously reported that navigation system improved the accuracy of acetabular component orientation in MIS THA comparing to manual technique. Conventional CT-based navigation system in revision THAs had two problems. First, it was difficult to get accurate surface registration because a presence of a bone loss prevented surface registration. Secondly, an artifact of CT images due to previous implants during a preoperative planning. For surgical approach (removal of implants), damages of bone easily occurred before surface registration. Damages of bone changed the landmarks for surface registration. These problems might lead the error of CT-based navigation system. On the other hand, FN and FCTN system does not need surface registration around acetabulum. This feature is great advantage to revision THA. Therefore, FN and FCTN system have theoritically would be friendlier for revision THA than CTN system. We also reported FCTN system showed superior accuracy than CTN system [2]. In the present study, there were no significant differences between three kinds of navigation systems. But, our volume of patients was too small to draw differences between systems. We need to continue this study to get more cases. However, in conclusion, an application of navigation system in revision THAs was effective and safe procedure to eliminates postoperative complications such as a malpositioning and post-operative dislocation,

Introduction. CT-based navigation system in total hip arthroplasty (THA) is widely used to achieve accurate implant placement. Now, we developed our own CT-based navigation system originally, and since then we have been conducting various analysis in order to use the system more effectively. We compared the accuracy of registration with this navigation system and land mark matching type navigation system. In this study, we evaluated the influence of the surgical approach to the accuracy of registration. Methods. Between June 2015 and February 2016, 28 consecutive uncemented THAs were performed in 26 patients. The preoperative diagnosis was osteoarthritis in 20 hips, osteonecrosis of the femoral hips in 5, and rheumatoid arthritis in 3. The newly developed navigation system was a CT based, surface matching type navigation system. We used newly developed navigation system and commercially available land-mark type CT-based navigation system in the setting of acetabular sockets under the same condition. After we fixed the cementless cup, we measured the cup setting angle of inclination and anteversion on each navigation system. Postoperative assessment was performed using CT one week after the operation, and measured the actual angle of the cup. Approach of operations were performed via posterolateral approach in 14 hips, and Hardinge approach in 14 hips. We calculated the absolute value of the cup angle difference between intra-operative value and post-operative value with each navigation system and compared the accuracy between each navigation system and surgical approach. Results. The mean inclination using the Land-mark type navigation(group L) was 38.3±3.8°, using our navigation system (group S) was 38.7±5.7 °, the mean anteverion on group L was 25.8±5.6°, and group S was 27.3±10.2°. The mean of actual inclination of the implants calculated by postoperative CT was 38.4±7.1°, the mean of actual anteversion was 25.8±8.3°. In comparison with the absolute value of the difference between intra-operative and post-operative date, the mean difference of inclination on group L was 6.5±5.7°, and group L was 3.7±3.1 °, the difference was significant (p<0.05). The mean difference of anteversion of group L was 4.7±4.6 °, group S was 4.0±3.3°. In group L, the mean of absolute value of the difference between intra-operative and post-operative date of inclination via Hardinge approach was 6.0±6.8°, and posterior approach was 7.9±4.5°. In group S, The mean difference of inclination via Hardinge approach was 3.0±1.8°, and posterior approach was 4.5±4.1°. In group L, The mean difference of anteversion of Hardinge approach was 4.2±4.1°, and posterior approach was 5.3±5.3°. In group S, The mean difference of anteversion of Hardinge approach was 3.8±3.5°, and posterior approach was 4.2±3.3°. Discussion. N-navi was superior on inclination of the acetabular socket setting. Considering surgical approach, the accuracy was not good via posterior approach. We should take surface matching points widely around the acetabulum, however, to take points of anterior the acetabulum via posterior approach was difficult because of the femur. It was the reason of decrease the accuracy via posterior approach. We should choose the area of surface matching points according to surgical approach to make the registration more accurate

Introduction: Modern navigation technology appears to be acquiring an established place in the fields of total knee arthroplasty. This technology helps the surgeon to apply his manual skills with greater precision and thus more effectively, and its positive impact on the quality of surgical treatment has already been demonstrated. The Surgetics navigation system described in this paper shows that the Technology can be adapted to the requirements of daily surgical practice, without compromising its utility to the surgeon. The Surgetics navigation system: The Surgetics navigation system represents a multifunctional tool, that can be used in a lot of fields in orthopedic surgery. For every special use as prosthesis, osteotomies ore ACL-replacement, the hard- and software is adapted thus not any compromise should be accepted for the surgical procedure. In total knee prostheses navigation no ct- scan is needed preoperatively, the patented bone morphing procedure is entering all the anatomic datas to the computer for an absolutely correct positioning of the implant. Consequently the pre- and intraoperative inputs are reduced to a minimum. Material: To evaluate the advantage of the Surgetics navigation system in total knee prosthesis, the technical datas of a non constrained knee prostheses with rotational platform (ESKA) had been entered in the system. The patient datas, concerning size of the knee joint, leg axes, center of rotation of the hip joint and ligament balance are transmitted by rigid bodies and a pointer with 6 reflecting markers each and a stereo infrared camera. The rigid bodies are fixed by two thin Steinmann-nails each in the tibial and femoral bone. On a monitor each step of the bone morphing and the surgical procedure is shown. Thus the bonecutting guides are placed in an absolutely correct position. The extension – and the flexion gap is presented as well for a precise ligament balancing. The additional time for using this system is not extending 15 minutes. Methods: 50 ESKA total knee prosthesis with rotational platform have been implanted with standard instrumentation and another 50 with the use of the Surgetics navigation system. In both groups the reason fore surgery has been nearly identic. In 92% the patients suffered from arthritis. More varus than valgus deformities have been seen. The range of deformity went up to 25 degrees.In 8% posttraumatic deformities with consecutive arthritis leaded to surgery. Preoperative X rays of the whole leg in a standing position have been taken, the shifting of the bearing axes in comparison to the center of the knee joint has been determined. The maximum of this shifting was 6.3 cm. The HSS score has been used to describe the clinical findings pre- and postoperativly. In 38 cases of the S- group and in 39 of the N- group the joint was inserted cementless. 2 in the s-group and 1 in the n-group in a hybrid technic, the rest cemented. Results: The follow up time in both groups ranged from 6 month to one year.Because it has not been the purpose of this paper to report on long time clinical results or survivership, this short follow up time seems to be acceptable for the evidence upon the value of a navigation system.The postoperative x- rays showed a correction of the bearing axes of the leg in relation to the center of the knee joint in a 4 degree corridor in 94,6% for the N – group and in 69,9% in the S- group. Two failures in the N-group came from a change of position of the rigid bodies during surgery due to pushing them by lack of caution. Conclusion: The surgetics navigation system is a technical help for the orthopedic surgeon, improving the radiological and clinical results in knee arthroplasty. The correction of the bearing axes in the 4 degree corridor is significantly higher in the N-group then in S-group. This has as well an important influence on the clinical outcome. The HSS score by first impression differs by 6 points. The use of the system is economically reasonable,because preoperative ct- scan is not needed and the time of surgery is not extended more than 15 minutes.The Surgetics navigation system with its sophisticated software is leading the surgeon visually through the bone morphing procedure, the bone cutting process and the ligament balancing step by step

Recently it has been increasing the interest of theorthopaedic surgeon about those tools o devices to optimize the results of the replacement surgery. In fact in the last few years the incidence of operations executed in order to treat patients affected by osteoarthritis of the hip with THR is increased, and so the need ness of giving back more long-lived implants. For this reason new navigation systems, based CT have been developed, which, during surgey, can make the positioning hip and knee prosthesis easier. A pool of international workers (surgeon, engineers, etc.) has developed recently an articular navigation system based on surgery reliefs, using tools gauged and provided with visible markers detected by a computerized system which uses infrared cameras. For this reason new navigation systems, based CT have been developed, which, during surgey, can make the positioning hip and knee prosthesis easier. A pool of international workers (surgeon, engineers, etc.) has developed recently an articular navigation system based on surgery reliefs, using tools gauged and provided with visible markers detected by a computerized system which uses infrared cameras. In fact it is not based on CT images of thehip, but on direct data (kept during the operation) analysis, and for this reason the procedure should be more accurate

Navigation has shown to improve limb and component alignment during total knee arthroplasty (TKA). However, most navigation systems involve bulky and expensive hardware, increased operative time and cost. A novel hand-held image-free navigation device has been recently approved with the aim to reduce inventory, cost and surgical time with its small size and quick registration features. We aimed to determine limb and component alignment and validate the accuracy of the iPod based navigation system. Intraoperative navigation data for proximal tibia and distal femur cuts, femoral component rotation, limb alignment and component alignment in routine imageless navigation system (Ci Navigation, Brainlab) was compared with the novel iPod-based hand-held navigation system (DASH, Smith & Nephew) in 20 TKAs. Postoperative full-length hip-to-ankle and lateral radiographs were evaluated to measure the hip-knee-ankle (HKA) angle and coronal and sagittal alignment of the femoral and tibial component. The iPod-based navigation system showed good agreement with the Ci Navigation system for limb alignment, tibial and distal femoral cuts in the majority of the limbs despite its quick registration feature. The iPod-based system is hence a positive step towards making navigation systems for TKA more compact, user-friendly, time and cost-effective

Imageless navigation is useful in acetabular cup orientation during total hip arthroplasty (THA). There is a limitation of accuracy in the imageless navigation system because of the registration method, that is, to palpate bony landmarks over the skin. To improve this limitation, ultrasound-based navigation was introduced for more precise registration of bony landmarks. We evaluated the accuracy of placement of the implant, which was measured by CT in 66 patients. 22 patients underwent THA with imageless navigation, and 44 patients underwent THA with ultrasound-based navigation. The accuracy was evaluated by comparison of the navigation values obtained during surgery with the CT measured values. For the 44 patients with ultrasound-based navigation system, the mean CIA was 39.6+4.1 degrees (mean+SD) and the CAA was 18.5+6.1 degrees with CT evaluation. Ultrasound-based navigation showed 39.0+3.2 degrees in CIA and 18.8+5.9 degrees in CAA during surgery. The mean absolute difference in cup inclination angle (CIA) between ultrasound-based navigation and CT was 2.4+2.1 degrees (range 0.1–9.2 degrees). The mean absolute difference in cup anteversion angle (CAA) between navigation and CT was 2.2+2.7 degrees (0.04–12.2 degrees). The rasp ante-torsion angle was 28.6+10.0 degrees in the ultrasound-based navigation system. The mean SAA was 28.8+9.3 degrees in CT. Strong correlation was found between the rasp ante-torsion angle and SAA (r=0.858). The mean absolute difference between the rasp ante-torsion angle and SAA was 4.3+3.6 degrees (0.2-17.2 degrees). For the 22 patients with imageless navigation system, the mean absolute difference between imageless navigation and CT in CIA, CAA, and SAA were 2.5+1.8 degrees (0.1–5.8 degrees), 5.4+3.8 degrees (0.1–17.2 degrees), and 5.2+3.0 degrees (1.1-12 degrees) respectively. The thickness of subcutaneous tissue at the pubic symphysis was correlated to the difference in CAA between the imageless navigation and CT (r=0.456). Ultrasound-based navigation showed higher accuracy in CAA compare to imageless navigation. Moreover, ultrasound-based navigation showed almost the same accuracy of placement of the implant compare to the reported accuracy with CT-based navigation. Ultrasound-based navigation system improved the limitation of accuracy in the imageless navigation system

Objectives. Few reports were shown about the position of the cup in total hip arthroplasty (THA) with CT-based navigation system. We use minimally invasive surgery (MIS) technique when we perform cementless THA and the correct settings of cups are sometimes difficult in MIS. So we use CT-based navigation system for put implants with correct angles and positions. We evaluated the depth of cup which was shown on intra-operative navigation system. Materials and Methods. We treated 30 hips in 29 patients (1 male and 28 females) by navigated THA. 21 osteoarthritis hips, 6 rheumatoid arthritis hips and 3 idiopathic osteonecrosis hips were performed THA with VectorVision Hip navigation system (BrainLAB). Implants were AMS HA cups and PerFix stems (Japan Medical Materials, Osaka). Appropriate angles and positions of cups were decided on the 3D model of pelvis before operation. According to the preoperative planning, we put the implants with navigation system. We correct the pelvic inclination angle and measured the depth of cups with 3D template software. Results. The average distance from the surface of the cup to the edge of medial wall of pelvis was 3.4mm (0.0–8.0mm) on the axial plane which include the center of femoral head on postoperative CT. The average distance from the surface of the cup to the edge of medial wall of pelvis was 6.4mm (1.5–15.0mm) on intraoperative navigation. The average error was 2.9mm (0.0–9.0mm). The cup positions of post operative CT were deeper than that of intraoperative navigation in twenty six hips (86%). Conclusions. The shallow setting of cups caused the instability of cups. Deep setting caused damage of acetabular fossa. The positions of cups on the navigation system tend to be shown shallower than actual positions, so we should take care of deeper setting

Introduction:. Since2007, we have used CT-based fluoroscopy-matching navigation system (Vector Vision Hip Ver.3.5.2, BrainLAB, Germany) in revision total hip arthroplasty. This system completes the registration procedure semi-automatically by matching the contours of fluoroscopic images and touching 3 adequate points to the contours of 3D bone model created in the computer. Registration procedure using fluoroscopic figures has finished before making surgical incision. It needs no elongation time during the operation. The objective of this study was to evaluate the accuracy of CT-based fluoroscopy-matching navigation system in revision THA. Material and method:. We analysed the acetabular cup in consecutive 33 hips with both intra-operative and post-operative alignment data (based on navigation system and CT evaluation) We further compared these measurements with results from primary THA. Data for primary THA were therefore obtained from 40 consecutive patients who underwent primary THA between August 2007 and May 2013 using the same navigation system by postero-lateral approach. We aimed the cup angle for Revision THA as following, the inclination: 40 degrees, the anteversion: 20 degrees Anteversion on the navigation system must be adjusted by the pelvic tilt. Results:. There was one dislocation in 33 Revision THAs. There was no other obvious complication (nerve palsy, VTE and Infection). The all cup alignments were within 7 degrees from the preoperative orientation. In the Revision THA group the differences between the intra- and post-operative measurement of cup inclination were 2.3 ± 1.9 degrees. The differences of cup anteversion were 2.7 ± 2.5 degrees. In the primary THA group, the differences between the intra- and post-operative measurement of cup inclination were 1.9 ± 2.1 degrees. The differences of cup anteversion were 2.1 ± 2.5 degrees. There was no significant difference with two groups. Discussion:. CT-based navigation THA is very useful for severe deformity of hip osteoarthritis. We had used CT-based navigation system (landmark matching) since 2003. It needs some technical skills to improve the accuracy of landmark matching. The registration with CT-based fluoroscopy-matching navigation system is much easier and more simple than with landmark matching navigation system. CT images of revision patients included metal artifacts caused by implants. However this system is not so affected by metal artifacts. And we found this system provided high accuracy even in revision THA

BACKGROUNDS. Total knee arthroplasty (TKA) using an imageless navigation is widely used in these days. Despite the usefulness of navigation-assisted TKA, there are still limitations of accuracy. From previous studies, many factors have been suggested as causes of the discordance between pre-op planning and post-op results. In Addition, Registration of reliable landmark is very important factor in navigation-assisted TKA, fundamentally. Nevertheless, current method of registration process is substantially affected by subjective preference of operators. Until now, However, there is no consensus about the optimal range of reference point. Moreover, the tolerance of imageless navigation system is still questionable. We investigated the effect of variation during the manual registration in this study. We compared the measured alignment and calculated plan of navigation system which were collected from repeated independent registration processes. METHODS. From 7 March 2016 to 13 May 2016, 44 patients (49 knees) underwent navigation assisted TKA with Orthopilot® Aesculap system. The subject group were severe osteoarthritis patients, they have evaluated radiographically and clinically before the operation. we excluded candidates who have shown very severe mal-alignment (>20 °) and metaphyseal bowing in Pre-op radiographic evaluation. All patients were followed for postoperative long axis film that could measure the correction angle, and followed clinically for functional score. Authors executed multiple registration trials in a single case, each trial was implemented by different surgeons (Senior surgeon JHJ and trainee LJH1, LJH2). At first, Senior surgeon (JHJ) start the operation from initial approach. Standard sub-vastus approach was applied to all-patients. After the procedure of joint exposure, each participating surgeon did the examination of knee anatomy and registered optimal point of his own. It was repeated three times (J,L1,L2) via imageless navigation system. Then, we collected the information of measured limb alignments and calculated plans of tibia cutting from navigation system. RESULTS. 33 knees were evaluated as Gr. 4 in Kellgren-Lawrence classification. The other 16 knees were Gr. 3. In repeated registration processes, patients who were scored Gr. 3 have shown no significant differences in mechanical limb alignments, both coronal and sagittal. There were also no significant differences in Gr. 4 patients, too. Initial tibia planning has shown the largest variance between medial and lateral cutting level (0.4 ± 1.3 mm, in neutral alignment). But, no statistical significance was observed. There is a tendency that the deviation of tibia planning has diminished gradually with the progression of this study. In radiographic evaluation, all cases have satisfactory limb alignments postoperatively. CONCLUSION. Our experiment suggest that variation of landmark registration alone couldn't have a significant effect on the calculated alignment of navigation system. In this study, we concluded that tolerable range of registration process for alignment calculation is relatively wide. Additionally, we think that the cutting depth is more vulnerable than alignment calculation, and it may need further study with more cases. Measured limb alignment is almost reliable in imageless navigation. Even though operators were not so experienced for the registration process

Introduction. While component malposition remains a major short and long term problem associated with total hip arthroplasty, enhanced technologies such as navigation and robotics have not yet been widely adopted. Both expense and increased OR time can be obstacles to adoption. The current study assesses the effect of the use of a smart mechanical navigation system on surgery time in total hip arthroplasty. Patients and Methods. 514 consecutive primary total hip arthroplasties were performed by a single surgeon from January 1, 2015 through March 31, 2016. Of these, 40 were performed using a smart mechanical navigation system (the HipXpert System, Surgical Planning Associates Inc., Boston, Massachusetts) and 474 were performed without navigation. The patients were not randomized. Incision to closure time (surgery time) was recorded for each procedure. A two tailed t-test was performed to assess statistical significance. Results. Mean surgery time for the non-navigated cases was 66 minutes. Mean surgery time for the navigated cases was 70 minutes. The difference in surgery time between the two groups was statistically significant (p=0.003). Conclusion. Adoption and use of a smart mechanical navigation system has a measurable increase in OR time of 4 minutes. This increase in OR time is quite small and with experience, is likely to further decrease. The amount of surgery time necessary for the use of the system is small compared to traditional navigation systems and especially to robotic systems. The study demonstrates that the adoption of a new smart mechanical navigation system increased surgery time very little. We anticipate that increased experience with the system will allow for the reduction in the need for intraoperative radiographs, which will further decrease surgery time and associated cost while simultaneously improving accuracy

INTRODUCTION. Several papers have reported the efficacy of an imageless navigation system in acetabular cup orientation during total hip arthroplasty (THA). Also, an imageless navigation system is useful for recovering leg length discrepancy. However, no study has evaluated the accuracy of the stem antetorsion angle (SAA) with an imageless navigation system in THA. The purpose of this study was to evaluate the accuracy of the stem antetorsion angles, which were measured by CT with the CT-free navigation system. Also, we evaluate the factors that affect the inaccuracy. MATERIALS AND METHODS. CT evaluation was performed in 60 patients (60 joints) who underwent primary THA from December 2011 to March 2014. Fifty-nine patients were female. The mean age at surgery was 67 years. The mean BMI at surgery was 24.0 kg/m2. Fifty-four patients had osteoarthrosis, 5 patients had osteonecrosis, and 1 patient had femoral neck fracture. All surgeries were performed in the supine position with the direct anterior approach. The OrthoPilot imageless navigation system was used during surgery. An Excia stem was used in 47 patients and a Bicontact stem was used in the other 13. Evaluation of SAA was carried out. Instead of SAA, the navigation indicates the rasp antetorsion angle based on the hip-knee-ankle plane during surgery. SAA based on the posterior condylar plane was measured with CT by using 3D THA plannning software. The accuracy of the imageless navigation system was evaluated by comparison of the navigation values obtained during surgery with the CT measured values. Correlations were analyzed with Pearson correlation analysis. RESULTS. The rasp antetorsion angle was 28.1±9.6 degrees [range 7.7–49.2 degrees]. The mean SAA was 29.9±8.9 degrees [10.7–49.7 degrees] in CT. Strong correlation was found between the rasp antetorsion angle and SAA (p<0.001, r=0.858, Figure). The difference between SAA and the rasp antetorsion angle (SAA – rasp antetorsion angle) was 1.8±4.7 degrees [-6.7–11.9 degrees]. The mean absolute difference between the rasp antetorsion angle and SAA was 4.0±3.1 degrees [0.2–11.9 degrees]. Forty-five cases (75%) showed less than 5 degrees of difference between SAA and the rasp antetorsion angle. Five cases (8.3%) showed more than 10 degrees of difference. In these five cases, SAAs were greater than the rasp antetorsion angles. Patients’ age, height, weight, and BMI did not affect the difference. Deformity of the femoral head, osteoarthrosis of the hip with subluxation, and osteoarthrosis of the knee were found in the patients who showed more than 5 degrees of difference between SAA and the rasp antetorsion angle. DISCUSSION. This study demonstrated that imageless navigation showed good accuracy for determining SAA during operation. This helps surgeons to recognize combined anteversion during surgery, and to avoid impingement after THA. This navigation system determines rasp antetorsion angle based on the hip-knee-ankle plane. The hip center is defined by setting the trial cup on the acetabulum. The knee center and the ankle center are defined by pointing over the skin. Therefore, deformity of the acetabulum or femoral head may affect the accuracy of the rasp antetorsion angle

INTRODUCTION. Traditionally, acetabular component insertion in direct anterior approach (DAA) total hip arthroplasty (THA) has been performed using fluoroscopic guidance. Handheld navigation systems can be used to address issues of alignment, cup placement and accuracy of measurements. Previous navigation systems have been used successfully in total knee arthroplasty (TKA) and has now been introduced in THA. We investigated the use of a new accelerometer-based, handheld navigation system during DAA THA to compare it to traditional means. This study aims to determine accuracy of acetabular cup placement as well as fluoroscopy times between two groups of patients. METHODS. Data was prospectively collected for a group of consecutive DAA THA procedures using a handheld navigation system (n=45) by a single surgeon. This was compared to data retrospectively collected for a group that underwent the same procedure without use of the navigation system(n=50). The time for use of the navigation system, including insertion of pins/registration, guiding cup position, and removal of pins, was recorded intraoperatively. Postoperative anteroposterior and cross-table lateral radiographs were used to measure acetabular inclination and anteversion angles. Targeted angles for all cases were 40° ±5 for inclination and 20° ±5 for anteversion. Intraoperative fluoroscopy exposure times were obtained from post-anesthesia care unit radiographs. RESULTS. Mean time of pin insertion/registration, cup positioning and removal was 180.5 seconds, 127.7 seconds and 26 seconds, giving a mean total time of 5.6 minutes. There were no significant differences in mean postoperative acetabular inclination angles between the navigation group as compared to the non-navigation group (39.8° vs 40.6°) (p = .2). There were no significant differences in mean postoperative acetabular anteversion angles between the navigation group as compared to the non-navigation group (24.3° vs 23.7°) (p=.5). Mean intraoperative fluoroscopy exposure times were significantly lower in the navigation group as compared to the non-navigation group (12.6 vs 22.2 seconds) (p<.0001). CONCLUSION. The findings demonstrated that a new handheld navigation system required minimal increase in operative time and was as accurate for cup positioning as fluoroscopically assisted DAA THA. Furthermore, there was a 45% reduction in fluoroscopy exposure time. Reduction in fluoroscopy time will lower radiation exposure for the surgeon and patients

Introduction. Proper acetabular cup placement is very important factor for successful clinical results in total hip arthroplasty (THA). Malposition of acetabular cup has been linked to increased rates of dislocation, impingement, pelvic osteolysis, cup migration, leg length discrepancy and polyethylene wear. Recently, some authors reported usefulness of navigation systems to set the acetabular cups with correct position. The purpose of this study is to evaluate the accuracy of acetabular cup placement in THA using computed tomography (CT)-based navigation system. Material and Methods. Subjects were 235 hip joints we performed primary THA using CT based navigation system (Stryker® Navigation System, Stryker Corporation, Kalamazoo, MI, USA) from 2008 to 2014 and could assess the implant position by postoperative CT images. Their average age was 65.1 years (range 35–88). In all cases, non-cemented acetabular cups were implanted. TriAD cups (Stryker®) were used in 31 hips, and Tritanium cups (Stryker®) were used in 15 hips, and Trident cups (Stryker®) were used in 189 hips. Registration in this navigation system used surface matching system. We designed cup implantation using preoperative CT images and 3-dimensional (3-D) templates. The planned position of acetabular cup was in principle 40 degrees of inclination and 20 degrees of anteversion. However, we adjusted the better position of the cups according to pelvic tilt and femoral neck anteversion. When we placed acetabular cups, the position, inclination and anteversion, were measured by navigation system. After surgery, the positions of the cups were measured using postoperative CT images, navigation software and 3-D templates. Postoperative position using CT images were adjusted according to preoperative pelvic plane. The discrepancies between intraoperative navigation data and postoperative CT images data were analyzed as accuracy of navigation system in cup placement. Results. No complications related to navigation procedures were encountered. There was no case with acetabular cup displacement obviously. The discrepancies between intraoperative data and postoperative data were an average difference of 1.6 degrees (SD, 1.4 degrees) for inclination and 2.1 degrees (SD, 1.7 degrees) for anteversion. Discussion and Conclusions. In THA, cup position is very important factor of postoperative long-term success. However, it is not easy to place the acetabular cup with proper position using conventional devices. CT-based navigation system was reported that it had many advantages than previous techniques in preoperative planning, setting the implants and analysis of postoperative data. But in registration with surface matching, learning-curve was pointed out and might be a problem for proper placement of implants. Therefore, we performed this study after some navigation THA cases. In the results of this study, the discrepancies between intraoperative and postoperative data were average 1.6 degrees for inclination and 2.1 degrees for anteversion. The accuracy of navigation system was good in inclination and anteversion of the cups, and there was no complication related it. CT-based navigation system is very useful device

Objectives. Few reports were shown about the position of the cup in total hip arthroplasty (THA) with CT-based navigation system. We use minimally invasive surgery (MIS) technique when we perform cementless THA and the correct settings of cups are sometimes difficult in MIS. So we use CT-based navigation system for put implants with correct angles and positions. We evaluated the depth of cup which was shown on intra-operative navigation system. Materials and Methods. We treated 30 hips in 29 patients (1 male and 28 females) by navigated THA. 21 osteoarthritis hips, 6 rheumatoid arthritis hips and 3 idiopathic osteonecrosis hips were performed THA with VectorVision Hip 2.5.1 navigation system (BrainLAB). Implants were AMS HA cups and PerFix stems (Japan Medical Materials, Osaka). Appropriate angles and positions of cups were decided on the 3D model of pelvis before operation. According to the preoperative planning, we put the implants with navigation system. We correct the pelvic inclination angle and measured the depth of cups with 3D template software. Results. The average distance from the surface of the cup to the edge of medial wall of pelvis was 3.4mm (0.0-8.0mm) on the axial plane which include the center of femoral head on postoperative CT. The average distance from the surface of the cup to the edge of medial wall of pelvis was 6.4mm (1.5-15.0mm) on intraoperative navigation. The average error was 2.9mm (0.0-9.0mm). The cup positions of post operative CT were deeper than that of intraoperative navigation in twenty six hips (86%). Conclusions. The shallow setting of cups caused the instability of cups. Deep setting caused damage of acetabular fossa. The positions of cups on the navigation system tend to be shown shallower than actual positions, so we should take care of deeper setting

Total hip arthroplasty (THA) is an effective treatment for symptomatic hip osteoarthritis (OA). Computer-navigation technologies in total knee arthroplasty show evidence-supported survivorship advantages and are used widely. The aim of this study was to determine the revision outcome of hip commercially available navigation technologies. Data from the Australian Orthopaedic Association National Joint Replacement Registry from January 2016 to December 2020 included all primary THA procedures performed for osteoarthritis (OA). Procedures using the Intellijoint HIP® navigation were identified and compared to procedures inserted using ‘other’ computer navigation systems and to all non-navigated procedures. The cumulative percent revision (CPR) was compared between the three groups using Kaplan-Meier estimates of survivorship and hazard ratios (HR) from Cox proportional hazards models, adjusted for age and gender. A prosthesis specific analysis was also performed. There were 1911 procedures that used the Intellijoint® system, 4081 used ‘other’ computer navigation, and 160,661 were non-navigated. The all-cause 2-year CPR rate for the Intellijoint HIP® system was 1.8% (95% CI 1.2, 2.6), compared to 2.2% (95% CI 1.8, 2.8) for other navigated and 2.2% (95% CI 2.1, 2.3) for non-navigated cases. A prosthesis specific analysis identified the Paragon/Acetabular Shell THAs combined with the Intellijoint HIP® system as having a higher (3.4%) rate of revision than non-navigated THAs (HR = 2.00 (1.01, 4.00), p=0.048). When this outlier combination was excluded, the Intellijoint® system group demonstrated a two-year CPR of 1.3%. There was no statistical difference in the CPR between the three groups before or after excluding Paragon/Acetabular Shell system. The preliminary data presented demonstrate no statistical difference in all cause revision rates when comparing the Intellijoint HIP® THA navigation system with ‘other’ navigation systems and ‘non-navigated’ approaches for primary THAs performed for OA. The current sample size remains too small to permit meaningful subgroup statistical comparisons

Implant malposition is one of the most common causes of failure in resurfacing arthroplasty of the hip (RAH). Recent advances in computer technology have made available navigation systems for RAH and other orthopaedic procedures. The purpose of our study was:. to develop a method to assess the accuracy of an image-free RAH navigation system;. to assess its accuracy in a leg with normal anatomy and with deformity of the proximal femur. We used the Ci-CAS RAH navigation system (DePuy - BrainLab). To facilitate measurements, an artificial leg (phantom) was constructed from machined aluminium with simulated hip and knee joints. The hip and knee articulating surfaces were synthetic bone material (Sawbones – Pacific Laboratories). An additional joint located at the trochanteric region allowed deformation in varus/valgus and ante/retroversion of the head/neck segment. Using a highly accurate digital calliper unit (FaroARM Technologies, USA) to precisely measure co-ordinates with pre-machined points on the phantom, a software program was developed to convert these local co-ordinates into a determination of actual anatomy and leg alignment. This technique was verified using repeated measurement with variable co-ordinates, giving accuracy to within 0.05 of a degree. Simulated procedures were performed with both normal and abnormal anatomy of the proximal femur. At specific points in the procedure, information was compared between the FaroARM digital measurements and the Ci-CAS system. Repeated serial measurements were undertaken. In the setting of normal alignment, accuracy to within 0.5 degrees was demonstrated. In the setting of abnormal alignment (varus/valgus and ante/retroversion) of the proximal femur, accuracy to within 2 degrees was demonstrated. To our knowledge, this is the first study to assess accuracy of a RAH navigation system. The study demonstrates a satisfactory level of accuracy for the Ci-CAS in both normal and abnormal anatomical settings. Currently, no international standard or methodology exists against which these results can be compared. In the near future, introduction of new navigation technologies will make crucial the development of international standards for pre-clinical validation of computer-assisted navigation systems. The present study is a first attempt to address this issue