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Mechanical feedback is one of the most common difficulties encountered when fitting hearing aids for toddlers and young children. We described the use of 3D printing to tailor a protective cap for a toddler with bilateral microtia/canal atresia to facilitate bone-anchoring hearing aid use.

The success of total knee arthroplasty (TKA) depends on restoration of the stability and biomechanical efficiency of the native knee. The emergence of robotic surgical technologies has greatly increased the precision and reproducibility. We discuss contemporary robotic TKA systems by reviewing the features of the individual platforms, their accuracy, and the clinical outcomes. While early results suggest significant gains in patient outcomes, long-term evidence is still awaited from multicenter prospective clinical trials. Moreover, advances in this technology are needed to address knee laxity while individualizing the functional performance of each patient's new joint., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Background and purpose - The accuracy of conventional navigation systems depends on precise registration of bony landmarks. We investigated the clinical use of electromagnetic navigation (EMN), with a unique device for precise determination of the anterior pelvic plane. Patients and methods - We randomly allocated patients scheduled for total hip arthroplasty into 2 groups of 42 patients each. In the study group, cups were placed at the predetermined target angles (inclination: 42.5°; anteversion: 15°) with the support of EMN. In the control group, cups were placed freehand aiming at the same target angles. Postoperatively the true position of the cup was determined using computed tomography scan of the pelvis. Precision (root mean squared error, RMSE) bias (mean bias error, ME), accuracy, and duration of surgery were compared between the methods. Results - Cup anteversion was more accurate and precise in the navigated group. The ME in the navigated and freehand group was -1.7° (95% CI -2.4 to 1.1) and -4.5° (CI -6.5 to 2.5), respectively. The RMSE in the navigated and freehand group was 2.8° (CI 2.3-3.2) and 8.0° (CI 6.3-9.5), respectively. The inclination was also more precise in the navigated group, with the RMSE in the navigated and freehand group at 4.6° (CI 3.4-5.9) and 6.5° (CI 5.4-7.5), respectively. The accuracy of the inclination and the duration of surgeries were similar between the groups. Interpretation - Cup placement with the help of EMN is more precise than the freehand technique and it does not affect the duration of surgery.

Backgroud: The aim of this study was to evaluate the difference between the planned and verified actual values in total knee arthroplasty (TKA) performed using a navigation system., Methods: Sixty patients who underwent primary TKA for knee pain from March 2018 to July 2018 were included in this study. All patients underwent TKA using the latest version of a computer navigation system (Kick ver. 2.6). All TKA procedures were performed by the same surgeon. The appropriateness of the use of navigation system in each of the several steps during the operation was investigated. Implant size was assessed using a preoperative template and after registration of landmarks with the navigation system. Intraoperative measurement was conducted using a femoral sizing implant apparatus. The difference between the planned value based on the navigation system and the actual cutting value was investigated. Intraoperatively confirmed hip-knee-ankle angle was also compared to the angle measured at postoperative 3 months., Results: The average time spent on the registration process was 242 seconds (range, 205-345 seconds). Intraoperative femoral component size tended to be smaller than the size recommended by the navigation system. A significant difference between the planned distal femoral cutting level (9.08 ± 0.40 mm) and the verified actual cutting level (9.87 ± 1.39 mm) was identified ( p < 0.05). The difference between the planned lateral and medial tibial resection levels (10.12 ± 0.34 mm and 4.47 ± 2.17 mm, respectively) and the verified actual lateral and medial tibial resection levels (9.07 ± 1.45 mm and 3.48 ± 2.00 mm, respectively) was statistically significant. Distal femoral cutting angle in sagittal plane was significantly different but femoral and tibial cutting angles showed no significant difference between the planned and verified values. At full extension, the average coronal alignment of the implant recorded after insertion of the actual implant using the navigation system was 0.23° ± 0.51° varus and showed no significant difference from the alignment measured at postoperative 3 months (0.45° ± 0.58°)., Conclusions: When performing navigation-assisted TKA, surgeons should aware that frequent errors can occur on the femoral cutting level, tibial cutting level, and implant sizing despite its reported advantage in defining the mechanical limb axis., Competing Interests: CONFLICT OF INTEREST: No potential conflict of interest relevant to this article was reported., (Copyright © 2020 by The Korean Orthopaedic Association.)

The purpose of this study was to evaluate intraope- rative alignment during total knee arthroplasty using a handheld navigation system, iAssist, in comparison with conventional optical surgical navigation. Sixty-two consecutive patients were enrolled in this prospective study. iAssist was used to determine implant component positioning. Orientation of the cuts were verified using a conventional optical sur- gical navigation system. We compared the iAssist system with the conventional system in terms of accuracy, percentage of outliers, bias, and precision. The occurrence of component malalignment was low. Taking standard radiography as the reference, there were no relevant differences between the handheld device and optical navigation in terms of measure- ment of accuracy or in outlier occurrence. Bias was small for both technologies, and precision was comparable. The study provides preliminary evidence that the use of iAssist leads to satisfactory implant alignment. The results from this study imply that iAssist could be a viable alternative to conventional optical navigation.

Background: Accurate orientation of acetabular and femoral components is important during total hip arthroplasty (THA). In recent years, several navigation systems have been developed. However, these navigation systems for THA are unpopular worldwide because of their high cost. We assessed the orientation accuracy of cups inserted using a disposable accelerometer-based portable navigation system for THAs., Methods: This was a prospective cohort study. We analyzed 63 hips with navigation prospectively and 30 hips without navigation retrospectively as historical control. The patients underwent THA via the mini anterolateral approach in the supine position using an accelerometer-based portable navigation system. We compared the preoperative target angles, intraoperative cup angles using navigation records, postoperative angles using postoperative CT data, measurement errors of cup angles, and clinical parameters such as sex, treated side, age at surgery, and body mass index (BMI)., Results: The average absolute error (postoperative CT-navigation record) was 2.7 ± 2.1° (inclination) and 2.7 ± 1.8° (anteversion), and the absolute error (postoperative CT-preoperative target angle) was 2.6 ± 1.9° (inclination) and 2.7 ± 2.2° (anteversion). The absolute error between postoperative CT and target angle with navigation was significantly lower than the error without navigation (inclination; p = 0.025, anteversion; p = 0.005). Cup malalignment (absolute difference of inclination or anteversion between postoperative CT and preoperative target angle of over 5°) was significantly associated with BMI value (OR: 1.3, 95% CI: 1.1-1.7). The absolute measurement error of cup inclination and anteversion was significantly correlated with patients' BMI (inclination error: correlation coefficient = 0.53, p < 0.001, anteversion error: correlation coefficient = 0.58, p < 0.001)., Conclusions: The clinical accuracy of accelerometer-based portable navigation is precise for the orientation of cup placement, although accurate cup placement was affected by high BMI. This is the first study to report the accuracy of accelerometer-based portable navigation for THA in the supine position., Competing Interests: Declaration of Competing Interest No funding or external support was received by any of the authors in support of or in any relationship to the study. The authors have no conflict of interest., (Copyright © 2019 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.)

Background: The most crucial aspect of a prosthesis is the socket, as it will directly determine gait stability and quality. The current standard of care ischial ramus containment socket is reported to increase coronal stability through gait; however, socket discomfort is the primary complaint among prosthetic users., Objectives: The purpose of this study is to compare ischial ramus containment to alternatives in the transfemoral amputee population. All subjects were fit with three different sockets: traditional ischial ramus containment, a dynamic socket, and a sub-ischial. In this study, authors hypothesized socket skeletal motion would be equivalent across interventions., Study Design: Single-blind, repeated-measures, three-period randomized crossover clinical trial., Methods: Outcome measures were socket comfort score and skeletal motion, viewed coronally with X-ray measuring the position of the skeleton in relationship to the socket in full weight-bearing and full un-loading., Results: The mean age was 38.2 and mean Amputee Mobility Predictor score was 40. Mean vertical movement, horizontal movement, single limb prosthetic stance, mean femoral adduction in swing and stance, and median socket comfort score were not statistically different., Conclusion: The socket design did not significantly effect skeletal motion and socket comfort. All socket designs are suitable depending on the patient-centric preferences and prosthetist skill set., Clinical Relevance: The comfort of the standard of care transfemoral amputation socket has been widely reported as problematic. A comparison of alternative designs in a controlled clinical trial environment will assist the clinician in understanding the impact of design regarding skeletal motion and comfort. Users could benefit from alternatives applied in clinical practice.

Objective: To compare the efficacy of the restoration of tibial component coronal alignment with a double-check technique and the conventional surgical technique during total knee arthroplasty (TKA) in knee osteoarthritis patients, and to investigate the distribution of the medial proximal tibial angle (MPTA) after TKA., Methods: A retrospective review was performed of 151 patients (179 knees) with knee osteoarthritis undergoing primary TKA in Beijing Chaoyang Hospital, Capital Medical University from February 2013 to January 2015 to evaluate the differences in MPTA in patients undergoing the conventional TKA and those undergoing a modified TKA with a double-check technique after the surgery. All patients were evaluated by MPTA, range of motion (ROM), Knee Society Clinical Rating System (KSS) clinical scores, and KSS functional scores. An MPTA deviation of 3° or greater was considered malalignment., Results: A total of 130 TKA procedures in 119 patients were included in the study: 64 knees treated with conventional TKA and 66 knees treated with the double-check technique TKA. The mean postoperative MPTA was 88.6° ± 2.2° in the conventional TKA group and 89.1° ± 1.5° in the double-check TKA group. The mean postoperative MPTA between the two groups was not significantly different. In the conventional TKA group, 79.7% (51 knees) had a postoperative MPTA deviation within 3° and 20.3% (13 knees) had a MPTA deviation greater than 3°. In the double-check TKA group, 93.9% (62 knees) had a postoperative MPTA deviation within 3°and 6.1% (4 knees) had a MPTA deviation greater than 3°. The postoperative MPTA deviation within 3° showed a statistically significant difference between the two groups. In the double-check TKA group, a 21.2% (14 knees) tibial malalignment was detected after the first check and a 9.1% (6 knees) tibial malalignment was detected after the second check. The mean postoperative ROM was 118.1° ± 9.2° in the conventional TKA group and 115.7° ± 10.1° in the double-check TKA group. The mean postoperative KSS clinical score was 89.3 ± 3.5 in the conventional TKA group and 89.0 ± 3.7 in the double-check TKA group. The mean postoperative KSS functional score was 84.8 ± 10.0 in the conventional TKA group and 84.9 ± 9.0 in the double-check TKA group. The mean postoperative ROM, KSS clinical scores, and KSS functional scores between the two groups were not statistically significantly different., Conclusion: Malalignment of the tibial component can occur after conventional TKA, and the double-check technique is an effective method to improve tibial component coronal alignment., (© 2019 The Authors. Orthopaedic Surgery published by Chinese Orthopaedic Association and John Wiley & Sons Australia, Ltd.)

Background: Catheter navigation and 3-dimensional (3D) cardiac mapping are essential components of minimally invasive electrophysiological procedures., Objective: The purpose of this study was to develop a novel 3D mapping system (KODEX - EPD, EPD Solutions, Best, The Netherlands) that measures changing electric field gradients induced on intracardiac electrodes to enable catheter localization and real-time 3D cardiac mapping., Methods: We first validated the accuracy of the system's measurement and localization capabilities by comparing known and KODEX - EPD-measured distances and locations at 12 anatomical landmarks in both the atria and ventricles of 4 swine. Next, in vivo images of 3D porcine cardiac anatomy generated by KODEX - EPD and widely used CARTO 3 system (Biosense Webster, Inc., Diamond Bar, CA) were compared with gold standard computed tomography images acquired from the same animals. Finally, 3D maps of atrial anatomy were created for 22 patients with paroxysmal atrial fibrillation (Dielectric Unravelling of Radiofrequency ABLation Effectiveness trial)., Results: First, the mean error between known and measured distances was 1.08 ± 0.11 mm (P < .01) and the overall standard deviation between known and measured locations in 12 areas of the porcine heart was 0.35 mm (P < .01). Second, an expert comparison of 3D image quality revealed that KODEX - EPD is noninferior to CARTO 3. Third, the system enabled 3D imaging of atrial anatomy in humans, provided real-time images of atrioventricular valves, and detected important anatomical variations in a subset of patients., Conclusion: The KODEX - EPD system is a novel 3D mapping system that accurately detects catheter location and can generate high-resolution images without the need for preacquired imaging, specialty catheters, or a point-by-point mapping procedure., (Copyright © 2019 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Objective: Total knee replacement (TKR) is a surgical treatment for final stage gonarthrosis. The lifespan of the prosthetic implants used in TKR surgery is a major interest for the orthopaedic research community.Previously, proper implant alignment of the implants has been advocated for longevity of the TKR surgery. Recently, patient-specific (PSI) instruments have been proposed to improve the mechanical alignment of the TKR by permitting better implant positioning over conventional TKR surgery. The aim of this study is to compare the mechanical alignment results of patients operated with PSIs and conventional instruments., Methods: Two groups of 20 patients chosen in a quasi-random manner have been compared in this study. In the first group femoral distal and tibial osteotomies were made by a PSI which was produced by the patients' computed tomography scans. All osteotomies in the control group were made with the TKR set's routine instruments by conventional means. Patients' preoperative and postoperative mechanical femorotibal angles (mFTA), femoral coronal angles (FCA), tibial coronal angles (TCA) were measured and the number of outliers which showed more than 3° of malalignment were counted in both groups for comparison., Results: The average postoperative mFTA was found to be 2.09° for the PSI group and in was found to be 2.84° for the control which was not statistically significant. The comparison of postoperative FCA and TCA also did not show significant difference between the groups. The number of outliers showing more than 3° of malalignment per group were found to be 1 out of 20 (5%) for the PSI group and 7 out of 20 (35%) for the control which was statistically significant., Conclusion: In this study patient-specific instrumentation provided significantly better mechanical alignment compared to conventional TKR for the frequency of outlier cases with malalignment beyond 3°. PSI proved no significant difference when the groups were compared for mFTA, FCA and TCA. Our findings support that PSI may improve TKR alignment by improving the ratio of the outlier patients with marked malalignment., Level of Evidence: Level III, Therapeutic Study., (Copyright © 2019 Turkish Association of Orthopaedics and Traumatology. Production and hosting by Elsevier B.V. All rights reserved.)

Introduction: Correct femoral rotational alignment in total knee arthroplasty (TKA) is important for femoropatellar knee kinematics as well as for the overall clinical success. The goal of the present study was to evaluate how accurately standard instruments of various manufacturers with specific rotational settings in posterior referencing restore the posterior femoral condylar anatomy and allow a rotational alignment which matches a particular anatomic rotational landmark on CT., Methods: The anatomical transepicondylar axis (aTEA) and the posterior condylar line (PCL) were identified and the angle formed by these two axes was measured on 100 consecutive CT scans of knees. A virtual posterior condylar resection was performed relative to the aTEA for femoral sizers of various manufacturers in different external rotations ranging from 3° to 7°. The resections of medial and lateral posterior condyle were calculated as well as the condylar twist angle (CTA) between PCL and aTEA., Results: The posterior condylar resection varied between 9 mm and 14 mm on the medial side and between 4 mm and 10.5 mm on the lateral side. The mean CTA was 5.5° of internal rotation (SD ± 1.9°). External femoral rotation resulted in increased resection of the medial posterior condyle and decreased resection of the lateral posterior condyle., Conclusion: Femoral sizers using a posterior referencing technique increase, with rising external rotation, medial posterior condylar resection to an extent that may exceed the implant thickness in the majority of systems. Surgeons should be aware that current standard instruments do not restore the anatomy of the posterior medial and lateral condyle and do not align the femoral component parallel to the aTEA, which may result in internal rotation of a symmetric femoral component.

Osseointegrated auditory devices (OADs) are hearing devices that use an external receiver/processor that stimulates bone conduction of sound via a titanium prosthesis that is drilled into the bone of the cranium. Since their introduction in 1977, OADs have undergone substantial evolution, including changes in manufacturing of the implant, improvements in the external sound processor, and simplification of implantation techniques. Expansion of criteria for patient candidacy for implantation has occurred corresponding with changes in the implants and processors., (Copyright © 2018 Elsevier Inc. All rights reserved.)

A new two-dimensional wireless and passive stress sensor using the inverse magnetostrictive effect is proposed, designed, analyzed, fabricated, and tested in this work. Three pieces of magnetostrictive material are bonded on the surface of a smart elastomer structure base to form the sensor. Using the external load, an amplitude change in the higher-order harmonic signal of the magnetic material is detected (as a result of the passive variation of the magnetic permeability wirelessly). The finite element method (FEM) is used to accomplish the design and analysis process. The strain-sensitive regions of the tension and torque are distributed at different locations, following the FEM analysis. After the fabrication of a sensor prototype, the mechanical output performance is measured. The effective measurement range is 0⁻40 N and 0⁻4 N·M under tension and torque, respectively. Finally, the error of the sensor after calibration and decoupling for F x is 3.4% and for T x is 4.2% under a compound test load (35 N and 3.5 N·M). The proposed sensor exhibits the merits of being passive and wireless, and has an ingenious structure. This passive and wireless sensor is useful for the long-term detection of mechanical loading within a moving object, and can even potentially be used for tracing dangerous overloads and for preventing implant failures by monitoring the deformation of implants in the human body.

Purpose: A simple overlay device (SOD) was developed to measure radial head implant length. The purpose of this study was to determine the accuracy and reliability of this device for measuring experimental radial head implant length., Methods: Five fresh frozen cadavers were implanted with sequentially longer implants, adjusted by neck length (0, 2, 4, and 8 mm). Fluoroscopic images were obtained in 4 forearm positions: anteroposterior in supination in full extension, anteroposterior in pronation in full extension, supinated in 45° of flexion, and neutral in 45° of flexion. The SOD measurements (made by 2 observers) were compared with the native original radial head (control) to assess implant length. In addition, gapping of the ulnohumeral joint space was measured for comparison purposes., Results: The measured radial head and neck lengths for the specimens were 33, 39, 31, 34, and 42 mm. The difference between the actual radial head and neck lengths and those measured with the SOD template averaged less than 2 mm for all 4 collar sizes, except in 1 measurement in which the bicipital tuberosity could not be visualized. The median intraclass correlation coefficients for observer 1 compared with the SOD were 0.94 to 0.99. The median intraclass correlation coefficients between observers were 0.88 to 0.95. For both observers, elbow position, collar height, and the 2 variables combined did not significantly affect the SOD values. The other method that was evaluated, that of measurement of the ulnohumeral joint space, had higher interobserver variability versus the SOD, and allowed detection of lengthening of over 4 mm., Conclusions: The SOD is a reliable method for simply assessing radial head length with radiographs and can accurately detect 2 mm or more of proximal radial lengthening., Clinical Relevance: The SOD is a simple and accurate method that can help to optimize radial head sizing., (Copyright © 2018 American Society for Surgery of the Hand. Published by Elsevier Inc. All rights reserved.)

Purpose: Patient-specific instrumentation (PSI) for total knee arthroplasty (TKA) may improve component sizing. Little has been reported about accuracy of the default plan created by the manufacturer, especially for CT-based PSI. The goal of this study was to evaluate the reliability of this plan and the impact of the surgeon's changes on the final accuracy of the guide sizes., Methods: Forty-five patients eligible for primary TKA were prospectively enrolled. The planned implant sizes were prospectively recorded from the initial manufacturer's proposal and from the final plan adjusted in light of the surgeon's evaluation; these two sizes where then compared to the actually implanted sizes. Fisher's exact test was used to test differences for categorical variables. Agreement between pre-operative plans and final implant was evaluated with the Bland-Altman method., Results: The manufacturer's proposal differed from the final implant in 9 (20.0%) femoral and 23 (51.1%) tibial components, while the surgeon's plan in 6 (13.3%, femoral) and 12 (26.7%, tibial). Modifications in the pre-operative plan were carried out for five (11.1%) femoral and 23 (51.1%) tibial components (p = 0.03). Appropriate modification occurred in 22 (88.0%) and 19 (76.0%) cases of femoral and tibial changes. The agreement between the manufacturer's and the surgeon's pre-operative plans was poor, especially with regard to tibial components., Conclusion: The surgeon's accuracy in predicting the final component size was significantly different from that of the manufacturer and changes in the initial manufacturer's plan were necessary to get an accurate pre-operative plan of the implant sizes., Clinical Relevance: Careful evaluation of the initial manufacturer's plan by an experienced knee surgeon is mandatory when planning TKA with CT-based PSI., Level of Evidence: II.

Prosthetic alignment is an essential process to rehabilitate patients with amputations. This study presents, for the first time, an invented device to read and record prosthesis alignment data. The digital device consists of seven main parts: the trigger, internal shaft, shell, sensor adjustment button, digital display, sliding shell, and tip. The alignment data were read and recorded by the user or a computer to replicate prosthesis adjustment for future use or examine the sequence of changes in alignment and its effect on the posture of the patient. Alignment data were recorded at the anterior/posterior and medial/lateral positions for five patients. Results show the high level of confidence to record alignment data and replicate adjustments. Therefore, the device helps patients readjust their prosthesis by themselves, or prosthetists to perform adjustment for patients and analyze the effects of malalignment.

Patient-specific instrumentation (PSI) was designed to improve the accuracy of preoperative planning and postoperative prosthesis positioning in total knee arthroplasty (TKA). However, better understanding needs to be achieved due to the subtle nature of the PSI systems. In this study, 3D printing technique based on the image data of computed tomography (CT) has been utilized for optimal controlling of the surgical parameters. Two groups of TKA cases have been randomly selected as PSI group and control group with no significant difference of age and sex ( p  > 0.05). The PSI group is treated with 3D printed cutting guides whereas the control group is treated with conventional instrumentation (CI). By evaluating the proximal osteotomy amount, distal osteotomy amount, valgus angle, external rotation angle, and tibial posterior slope angle of patients, it can be found that the preoperative quantitative assessment and intraoperative changes can be controlled with PSI whereas CI is relied on experience. In terms of postoperative parameters, such as hip-knee-ankle (HKA), frontal femoral component (FFC), frontal tibial component (FTC), and lateral tibial component (LTC) angles, there is a significant improvement in achieving the desired implant position ( p  < 0.05). Assigned from the morphology of patients' knees, the PSI represents the convergence of congruent designs with current personalized treatment tools. The PSI can achieve less extremity alignment and greater accuracy of prosthesis implantation compared against control method, which indicates potential for optimal HKA, FFC, and FTC angles., Competing Interests: Disclosure The authors report no conflicts of interest in this work., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

Proper coronal and transverse ligament balancing is an important aspect of total knee arthroplasty (TKA) and has an impact on postoperative outcome. Many variations of the gap balancing technique were described to address this challenge, most of them using various tensioning devices, but none for which the use is widespread. The aim of this paper is to describe a gap technique variant for TKA using spacer blocks and report the clinical results for a cohort of patients on which it was used. A total of 114 TKAs were performed in 101 patients using a standardized surgical technique that integrates ligament balancing with sizing and positioning of the femoral component. Clinical variables were assessed preoperatively and after a mean follow-up of 43 months using the Knee Society score, the Knee injury and Osteoarthritis Outcome Score (KOOS), and the International Knee Documentation Committee (IKDC) score. A significant improvement in every clinical function score was noted at the latest follow-up compared with preoperative values. All the knees except four (96%) were well-balanced at the last follow-up examination; a firm but delayed end-point was noted in the remaining four knees but did not seem to affect patient outcome. The patellar button was centered in the prosthetic trochlear groove for all knees on the postoperative radiographs. Similar improvements in the scores and in range of motion were noted for knees with a preoperative coronal misalignment of 10 degrees or more ( n  = 26) compared with knees with less than 10 degrees of varus or valgus ( n  = 77). The described surgical technique appears to be reliable to obtain well-balanced knees and good patellar tracking when performing a primary TKA, even in knees with important coronal misalignment., Competing Interests: Disclosure The authors report no conflicts of interest in this work., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

Exoskeletons and active prostheses promise to enhance human mobility, but few have succeeded. Optimizing device characteristics on the basis of measured human performance could lead to improved designs. We have developed a method for identifying the exoskeleton assistance that minimizes human energy cost during walking. Optimized torque patterns from an exoskeleton worn on one ankle reduced metabolic energy consumption by 24.2 ± 7.4% compared to no torque. The approach was effective with exoskeletons worn on one or both ankles, during a variety of walking conditions, during running, and when optimizing muscle activity. Finding a good generic assistance pattern, customizing it to individual needs, and helping users learn to take advantage of the device all contributed to improved economy. Optimization methods with these features can substantially improve performance., (Copyright © 2017 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.)

Background: Glenoid component positioning in revision shoulder arthroplasty is difficult because of distorted anatomic landmarks and scarring in and around the glenoid vault. This study compared glenoid component version in revision total shoulder arthroplasty (TSA) and reverse TSA (RTSA) using traditional instrumentation vs. a generic glenoid targeting guide., Methods: Radiographs of 50 shoulders undergoing revision arthroplasty were reviewed by an independent reviewer. Twenty-one components were placed using traditional instrumentation and 29 with a generic targeting guide. Glenoid component version was measured on axillary lateral radiographs, and absolute deviation from anatomic version was calculated., Results: The average deviation in version from anatomic was 8° (range, 0°-21°) with the traditional technique and 5° (range, 0°-18°) with the targeting guide (P = .03). In revision to TSA, the average deviation was 10° with the traditional technique and 3° with the targeting guide (P = .01). There was no significant difference in revision to RTSA (average deviation was 8° with traditional technique and 6° with the targeting guide). Glenoid components in obese patients (body mass index  >30 kg/m 2 ) had less deviation (5°) with the targeting guide technique than with the traditional technique (9°, P = .04). No significant differences were found between techniques in glenoids with more than 15° of preoperative retroversion, TSA conversion to RSTA, or arthroplasty after proximal humeral fixation., Conclusions: For revision arthroplasty, glenoid components placed with the generic targeting guide were significantly more accurate in version than with traditional instrumentation, particularly with revision to anatomic TSA. The targeting guide was useful in obese patients., (Copyright © 2017 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Objective: Bicompartmental knee replacement in patients with combined osteoarthritis (OA) of the medial or lateral and patellofemoral compartment. Patient-specific instruments and implants (ConforMIS iDuo™) with a planning protocol for optimal implant fit., Indications: Bicompartmental OA of the knee (Kellgren & Lawrence stage IV) affecting both the medial or lateral and patellofemoral compartment after unsuccessful conservative or joint-preserving surgery., Contraindications: Tricompartmental OA, knee ligament instabilities, knee deformities >15° (varus, valgus, extension deficit). Relative contraindication: body mass index >40; prior unicompartmental knee replacement or osteotomies., Surgical Technique: Midline or parapatellar medial skin incision, medial arthrotomy; identify mechanical contact zone of the intact femoral condyle (linea terminalis); remove remaining cartilage and all osteophytes that may interfere with the correct placement of the individually designed instruments. Balance knee in extension with patient-specific balancing chips. Resection of proximal tibia with an individual cutting block; confirm axial alignment using an extramedullary alignment guide, balance flexion gap using spacer blocks in 90° flexion. Final femur preparation with resection of the anterior trochlea. After balancing and identification of insert heights, final tibial preparation is performed. Implant is cemented in 45° of knee flexion. Remove excess cement and final irrigation, followed by closure., Postoperative Management: Sterile wound dressing; compressive bandage. No limitation of active/passive range of motion (ROM). Partial weight bearing the first 2 weeks, then transition to full weight bearing. Follow-up directly after surgery, at 12 and 52 weeks, then every 1-2 years., Results: In all, 44 patients with bicompartmental OA of the medial and patellofemoral compartment were treated. Mean age 59 years. Minimum follow-up 12 months. Implant converted to TKA due to tibial loosening (1 patient); patella resurfacing (3 patients). No further revisions or complications. Radiographic analyses demonstrated ideal fit of the implant with less than 2 mm subsidence or overhang. KSS pain scores improved from preoperatively 5.7 to 1.7 postoperatively with level walking, and from 7.3 preoperatively to 2.8 postoperatively with climbing stairs or inclines. The WOMAC score improved from preoperatively 43 to 79 postoperatively.

Due to demographic changes the proportion of elderly and very old, edentolous patients in need of care increases. More­ over, implant supported dentures are in many cases unfeasible for various reasons. Therefore, new time­ and cost­efficient strategies for manufacturing complete dentures are required. In this case report the Baltic Denture System, a new CAD/CAM process to manufacture complete dentures with standardized dental set­ups was tested. In the first appointment, a combi­ nation of functional impression as well as bite registration was carried out by means of specified registration devices, the BDKeys®. Subsequently, the relined and locked Upper and Low­ er Keys are transferred to the dental laboratory, digitized and the new dentures are milled from special blanks. In the second appointment the patient received the finished dentures. De­ spite some difficulties in the impression/registration step the patient was provided with very appealing new digital dentures. Thus, the Baltic Denture System might be an interesting new CAD/CAM alternative for manufacturing of complete dentures.

Background: Cochlear implantation in routine cases with normal anatomy is commonly performed without intraoperative image guidance. Revision cochlear implantation as well as surgery in malformations require not only a precise understanding of the underlying complex anatomy, but surgeons need to transform two-dimensional computed tomography (2D CT) scans into the surgical field and use this information for intraoperative surgical navigation. So far, information about the exact position of the electrode during insertion cannot be provided to the surgeon. Here, we present our first operative experience with cochlear implant surgery supported by intraoperative Dyna-CT technology, providing the surgeon with detailed views of the electrode location., Methods: To prove the feasibility of the procedure, two cases of cochlear implantation were performed with intraoperative application of cone-beam CT acquired by a C-arm Dyna-CT system (Artis Zeego, Siemens Healthcare, Erlangen, Germany). Image reconstruction was performed intraoperatively in order to assess the correct positioning of the electrodes., Results: Intraoperative Dyna-CT enabled clear visualization of the surgical anatomy and intracochlear electrode position. Dyna-CT technology can be applied with acceptable additional time requirements without adding too much complexity to the surgical procedure., Conclusion: Intraoperative data acquisition by Dyna-CT represents a suitable option for online surgical navigation during cochlear implant surgery. This imaging technology will push further advances in cochlear implant surgery and lateral skull base surgery, particularly if linked to intraoperative navigation.

We present a case where conventional wire and equipment passage through the proximal cap of a chronic total occlusion due to in-stent restenosis was not possible. The lesion was then safely and successfully treated by deliberate passage into the subintimal space outside the previous stent with subsequent subintimal dissection and reentry into the true lumen beyond the occlusion. We then stented around the occluded stent, effectively crushing the previous stent in the true lumen and restoring flow by stenting open the new subintimal lumen. Follow-up angiography and optical coherence tomography at 6 months demonstrated good medium-term results.

Three dimensional (3D) printing can be used to create material models to aid preoperative planning of complex orthopedic procedures as exemplified by this case of total hip arthroplasty failure due to infection with resulting severe acetabular bone stock deficiency. The 3D model allowed for trialing of the acetabular component to determine cup size, position, and screw placement. Most importantly, the model confirmed that there was not a pelvic discontinuity and the revision shell would be sufficient for the reconstruction. Previously, the cost and complexity of utilization of 3D printers were prohibitive. Recent improvements in commercially available 3D printers have made rapid prototype model creation a realistic option, which can facilitate difficult surgery.

Aim: The transcatheter aortic valve SAPIEN 3 aims at reducing paravalvular leakage (PVL). The new design with outer sealing cuff may increase the risk of permanent pacemaker implantation (PPM). The aim of our study was to evaluate the optimal implantation height of the SAPIEN 3., Methods and Results: We analysed the correlation between the implantation height of the valve and the need for PPM in 131 patients. The PPM rate for the entire group after TAVI was 18% (n = 24). In patients with a marker distance <2 mm ("low implantation"), the PPM rate was 32%, whereas in patients with a distance ≥2 mm ("high implantation"), the rate was only 4.7% (OR of 0.1 (0.03-0.37, P < 0.001))., Conclusion: The risk of periprocedural PPM with the Edwards SAPIEN 3 depends on implantation height; it is increased when using conventional implantation techniques. This risk can be minimized below 5% PPM by choosing a higher implantation technique with the central marker 2 mm or more over the annulus plane., (© 2016, Wiley Periodicals, Inc.)

Purpose: The aim of this study was to evaluate the duration of the preoperative examination and patient comfort in measurements with an Image Guided System (Verion, Alcon), which is used for the calculation and intraoperative alignment of toric intraocular lenses, in comparison to established keratometry devices., Patients and Methods: In a prospective, monocentric, open, ethics committee controlled study, 150 eyes of 150 ophthalmologically healthy volunteers were examined by a single examiner. Three measurements were performed with the Verion Image Guided System and - for comparison - one measurement each with IOLMaster 500, Lenstar LS900 and Pentacam HR. The measurement time was recorded with a stopwatch. For the analysis, patients were divided into three age groups (young, middle, old). Patient comfort was assessed using a questionnaire, which focussed on grading the whole measurement, as well as brightness of light, head posture and subjective duration., Results: The mean age of the volunteers was 40.5 years (18-78 years). The mean duration of measurement was as follows: first Verion measurement 54.0 ± 42.7 seconds (n = 149), second Verion measurement 42.0 ± 20.5 s (n = 144), third Verion measurement 44.7 ± 25.2 s (n = 143), IOLMaster 500 46.3 ± 22.4 s (n = 147), Lenstar LS900 46.6 ± 14.4 s (n = 146) and Pentacam HR 46.6 ± 25.5 s (n = 147). Only the first and second Verion measurements were statistically different (p < 0.01). There were no statistical differences between the age groups, with the single exception of young versus old with the Pentacam (p < 0.01). Subjective patient comfort (n = 143) was very high for all devices and rated as "not uncomfortable" or "slightly uncomfortable"., Conclusion: The duration of the preoperative examination with the Verion Image Guided System is comparable to established keratometry devices. However, IOL calculation with the Verion requires measurement of axial length and anterior chamber depth with another biometric device, which requires additional time. No age dependent differences were found. The examination can be easily integrated into clinical routine and is well tolerated by patients., (Georg Thieme Verlag KG Stuttgart · New York.)

Aims: This prospective randomised controlled trial was designed to evaluate the outcome of both the MRI- and CT-based patient-specific matched guides (PSG) from the same manufacturer., Patients and Methods: A total of 137 knees in 137 patients (50 men, 87 women) were included, 67 in the MRI- and 70 in the CT-based PSG group. Their mean age was 68.4 years (47.0 to 88.9). Outcome was expressed as the biomechanical limb alignment (centre hip-knee-ankle: HKA-axis) achieved post-operatively, the position of the individual components within 3° of the pre-operatively planned alignment, correct planned implant size and operative data (e.g. operating time and blood loss)., Results: The patient demographics (e.g. age, body mass index), correct planned implant size and operative data were not significantly different between the two groups. The proportion of outliers in the coronal and sagittal plane ranged from 0% to 21% in both groups. Only the number of outliers for the posterior slope of the tibial component showed a significant difference (p = 0.004) with more outliers in the CT group (n = 9, 13%) than in the MRI group (0%)., Conclusion: The post-operative HKA-axis was comparable in the MRI- and CT-based PSGs, but there were significantly more outliers for the posterior slope in the CT-based PSGs., Take Home Message: Alignment with MRI-based PSG is at least as good as, if not better, than that of the CT-based PSG, and is the preferred imaging modality when performing TKA with use of PSG. Cite this article: Bone Joint J 2016;98-B:786-92., (©2016 The British Editorial Society of Bone & Joint Surgery.)

In this article the evolution beginning with the robotics of total knee arthroplasty to CT-based and kinematic navigation and patient-specific instruments is described. Thereby it is pointed out that in the early 1990s, CT imaging solely for the planning of a knee endoprosthesis was considered as obsolete radiation exposure and this led to the widespread development of kinematical systems.Also a patient specific planning tool based on CAD built acryl harz blocs existed at the time. There is an ongoing process of implanting total knee arthroplasties in a more exact position. Nowadays the new evolution of soft tissue balancing by using a kinematic alignment has put these efforts into perspective.

Background: The story of ShapeMatch® custom-fit cutting guides for primary total knee arthroplasty (TKA) is special compared to other available techniques. First, it was the first such patient-specific instrument (PSI) on the market. Second, the underlying philosophy of kinematic alignment is unique compared to other competitors. Finally, it is the only PSI technique that has been withdrawn from the market., Objectives and Methods: The objective of this paper is to summarize the history of the ShapeMatch® technology and to review the current literature regarding clinical evidence for kinematically aligned TKA., Results and Conclusions: In the recent literature, faster rehabilitation, better knee function and higher patient satisfaction are described for kinematically aligned TKA compared to conventional alignment. However, there is also evidence for inaccuracies by using the PSI technology as a possible cause of treatment failures. Due to those problems, this technology was recalled from the market. As an alternative method to achieve kinematic alignment in TKA, manual as well as computer-assisted techniques are currently under development and are discussed here.

Background: Accurate component positioning and correct post-operative whole-leg alignment are crucial for ensuring the optimal long-term performance of a knee replacement. Patient-specific instrumentation (PSI) was introduced in an attempt to reduce outliers in the positioning of components and in the alignment of the leg axis in comparison with conventional techniques., Methods and Results: A review of our own investigations and studies by other groups, it has been shown that PSI could reduce the amount of outliers in the positioning of tibial and femoral components and in whole-leg alignment. In this way, PSI differs from other procedures for improving component placement, such as navigation, for which no advantage could be demonstrated, especially with regard to rotation in comparison with conventional techniques. In this publication we focus on the VISIONAIRE PSI system (Smith&Nephew). In addition, the efficiency aspects of PSI are discussed, which differ from the conventional method because of the use of disposable instruments.

Knee arthroplasty is a successful standard procedure in orthopedic surgery; however, approximately 20 % of patients are dissatisfied with the clinical results as they suffer pain and can no longer achieve the presurgery level of activity. According to the literature the reasons are inexact fitting of the prosthesis or too few anatomically formed implants resulting in less physiological kinematics of the knee joint. Reducing the number of dissatisfied patients and the corresponding number of revisions is an important goal considering the increasing need for artificial joints. In this context, patient-specific knee implants are an obvious alternative to conventional implants. For the first time implants are now matched to the individual bone and not vice versa to achieve the best possible individual situation and geometry and more structures (e.g. ligaments and bone) are preserved or only those structures are replaced which were actually destroyed by arthrosis. According to the authors view, this represents an optimal and pioneering addition to conventional implants. Patient-specific implants and the instruments needed for correct alignment and fitting can be manufactured by virtual 3D reconstruction and 3D printing based on computed tomography (CT) scans. The portfolio covers medial as well as lateral unicondylar implants, medial as well as lateral bicompartmental implants (femorotibial and patellofemoral compartments) and cruciate ligament-preserving as well as cruciate ligament-substituting total knee replacements; however, it must be explicitly emphasized that the literature is sparse and no long-term data are available.

This article describes the concept and surgical technique of patient-specific total knee arthroplasty. Patient-specific implants and instruments are designed and fabricated based on computed tomography (CT) data of the leg. The disposable patient-specific drill guides and cutting-jigs are manufactured taking into consideration the anatomical and biomechanical axes of the knee joint and mediating the efficient pre-navigation of the osseous saw-cuts, without the need for additional navigation or balancing aids. The surgical plan is made on the basis of the CT data. The implantation technique comprises the following steps: distal femoral resection, tibial resection, balancing and femur preparation, tibia preparation, optional patellar resurfacing, trialling of the test components, and implantation of the final components. By using this patient-specific implant system, which includes not only personalized, single-use instruments, but also individualized implants, the surgeon is able to provide endoprosthetic treatment that broadly restores the patient's own knee anatomy and knee kinematics. Preliminary studies have proven the concept and data on this technology are promising so far; however, like a new implant, they are usually limited. In particular, comparative long-term clinical data are still to come.

Purpose: Keratoconus is characterized by bilateral asymmetrical corneal ectasia that leads to inferior stromal thinning and corneal protrusion. There is currently a lack of consensus regarding the most efficacious method for fitting contact lenses in patients with keratoconus, given the various topographical patterns and evolution grades observed in affected populations. The purpose of the present study was to evaluate the association between keratoconus evolution grade and topography pattern and the type and design of fitted contact lens., Methods: We performed a retrospective analysis of contact lenses fitted in a total of 185 patients with keratoconus (325 eyes). Keratoconus was classified as either grade I, II, III, or IV based on keratometry and cone morphology (nipple, oval, globus, or indeterminate) results., Results: A total of 325 eyes were evaluated in the present study. Of the 62 eyes classified as grade I, 66.1% were fitted with monocurve contact lenses. Of the 162 eyes classified as grade I and II, 51%, 30%, and 19% were fitted with adapted monocurve rigid gas-permeable contact lenses (RGPCL), bicurve lenses, and others lens types, respectively. Bicurve lenses were fitted in 52.1% and 62.2% of eyes classified as grade III and IV, respectively. Of the eyes classified as grade III and IV, monocurve and bicurve RGPCL were fitted in 26% and 55%, respectively. In eyes with oval keratoconus, 45%, 35%, and 20% were fitted with monocurve lenses, bicurve lenses, and other lens types, respectively. In eyes with round cones (nipple morphology), 55%, 30%, and 15% were fitted with bicurve lenses, monocurve lenses, and other lens types, respectively., Conclusion: Monocurve RGPCL were most frequently fitted in patients with mild to moderate keratoconus and oval cones morphology, while bicurve lenses were more frequently fitted in patients with severe and advanced keratoconus. This was probably because bicurve lenses are more appropriate for round cones due to increased corneal asphericity.

Background: Adequate three-dimensional component positioning and restoration of overall limb alignment are primary goals in total knee arthroplasty. Patient-specific instrumentation (PSI) is a potential way to improve accuracy of knee reconstruction surgery. However, currently available literature regarding the reliability of PSI shows inconsistent results for limb alignment restoration and component positioning., Objectives: The purpose of this article is to illustrate the rationale for using PSI in total knee arthroplasty, to demonstrate the surgical technique, and to present our outcome with the MyKnee(®) system., Methods: We illustrate in detail the logistics and workflow involved in PSI for total knee arthroplasty. Finally, we present clinical and radiological results of patients undergoing knee arthroplasty using the MyKnee(®) system compared to a conventional instrumentation group., Results: PSI significantly improved accuracy and reduced the number of outliers regarding neutral mechanical alignment restoration as well as three-dimensional component positioning compared to conventional instrumentation. The early clinical outcome was comparable between the two instrumentation groups. However, clinical outcome in the subgroup of patients within ± 3° from neutral mechanical limb alignment was superior to limb alignment outliers., Conclusion: The MyKnee(®) PSI system presents a reliable way to improve the accuracy of mechanical limb alignment restoration and three-dimensional component positioning in total knee arthroplasty. Nonetheless, an adequate surgical technique remains the crucial factor for successful total knee reconstruction.

Background: The objective of patient-specific instrumentation (PSI Zimmer®) technology is to optimize positioning and selection of components as well as surgical procedure in uni- and bicompartimental knee replacement. The article contains a description of the planning and surgical technique and evaluates the method based on own results and literature., Methods: Using MRI or CT scans a virtual 3D model of the joint is created in order to simulate and plan the implant positioning. According to these data, pin placement and/or cutting guides are produced, which enable the surgeon to transfer the planning to the surgical procedure. In a prospective comparative study 88 patients (44 per each of the two techniques) were operated by one surgeon receiving the same TKA using either MRI-based PSI or a conventional technique. The number of surgical trays, operating time, intraoperative changes and frontal alignment using a full leg x‑ray (70 cases) were compared. In 17 patients the method was applied with unicondylar knee replacement., Results: Anatomical abnormalities could be detected preoperatively and considered during the operation. With PSI the number of trays could be reduced and predictability of the component size was more precise. Intraoperative changes became necessary only for distal femoral (25 %) and proximal tibial (36 %) resection and tibial rotation (40 %). Alignment was more precise in the PSI cases, Discussion: PSI using the applied technique proved to be practicable and reliable. The advantages of precise planning became obvious. Results concerning alignment are inconsistent in the literature. Soft tissue balancing has only been included in the technique to a limited degree so far. PSI is still in an early stage of development and further development opportunities should be exploited before final assessment.

Implant positioning is one of the critical factors influencing postoperative outcomes in total hip arthroplasty (THA). Several studies have reported that the postoperative antetorsion (AT) measurement for the femoral stem inserted without navigation showed wide variability. The current authors developed a simple instrument, the Gravity-guide (G-guide), for intraoperative assessment of stem AT and adjustment. They evaluated the effectiveness of the G-guide with postoperative computed tomography (CT) examination. Ninety patients (96 hips) who underwent primary THA using the G-guide for stem adjustment were evaluated. The G-guide consists of 2 parts: one attached to the lower leg and the other attached to the handle of the rasp. The G-guide was used to evaluate the AT at the time of inserting the final rasp. In addition, the AT value in the G-guide evaluation system required correction by the angle obtained in the preoperative epicondylar view. Intraoperative stem AT was defined as the sum of the intraoperative G-guide value and the correction angle. Postoperative AT was evaluated by CT examination. The discrepancy between the intra- and postoperative measurements was 4.6°±4.1°. Acceptable accuracy with discrepancy of less than 5° and 10° was achieved in 66 (69%) hips and 85 (89%) hips, respectively. The use of the G-guide could effectively reduce the variability of stem anteversion compared with manual adjustment. This study proved the effectiveness of the newly developed G-guide system in intraoperative stem AT adjustment., (Copyright 2016, SLACK Incorporated.)

Purpose: Total knee arthroplasty (TKA) is a challenging procedure in patients with a high body mass index (BMI). The aim of our study was to assess the outcome and accuracy of restoration of mechanical alignment in TKA using patient-specific guides (PSG) involving patients with high BMI., Materials and Methods: Patients with BMI of 30 or above were enrolled in the study. The mean age of the patients was 65.15 years. The study comprised of 46 males and 54 females. Total knee arthroplasty was planned after a pre-operative MRI and long leg x-ray films using customized PSG., Results: Of the 105 knees (100 patients) in the study, average BMI was 35.42 kg/m(2) (30-56). Twenty patients (20 %) had class III obesity (≥40 kg/m(2)). The average blood loss and operative time were 236.1 ml (range 50-700 ml) and 92.2 min (65-130 min), respectively. The average post-operative mechanical axis was noted to be 1.85° varus (range 4° valgus to 6° varus). Eighty-eight patients (86.27 %) had mechanical alignment within 3° of neutral. There were no adverse intraoperative events. One patient had deep infection that required a two-stage revision. The average post-operative range of motion at 1-year follow-up was 105.8° (range 80°-130°)., Conclusion: Patient-specific guides technology restores the coronal mechanical axis reliably in obese patients without adversely affecting outcomes. Our short-term follow-up has shown favorable outcomes. Surgeons should use these customized jigs as a guide and adjust the size of components, alignment and rotation according to normal surgical principles.

Purpose: The study was aimed at biomechanical evaluation of a novel Limb Prosthesis Osseointegrated Fixation System (LPOFS) designed to combine the advantages of interference-fit and threaded solutions., Methods: Three cases, the LPOFS (designed), the OPRA (threaded) and the ITAP (interference-fit) implants were studied. Von-Mises stresses in bone patterns and maximal values generated while axial loading on an implant placed in bone and the force reaction values in contact elements while extracting an implant were analysed. Primary and fully osteointegrated connections were considered., Results: The results obtained for primary connection indicate more effective anchoring of the OPRA, however the LPOFS provides more appropriate stress distribution (lower stress-shielding, no overloading) in bone. In the case of fully osteointegrated connection the LPOFSs kept the most favourable stress distribution in cortical bone which is the most important long-term feature of the implant usage and bone remodelling. Moreover, in fully bound connection its anchoring elements resist extracting attempts more than the ITAP and the OPRA., Conclusions: The results obtained allow us to conclude that in the case of features under study the LPOFS is a more functional solution to direct skeletal attachment of limb prosthesis than the referential implants during short and long-term use.

Presented in the articles is a case report of successfully using hybrid prosthesis "E-vita Open plus" (Jotec) in surgical treatment of a female patient presenting with type I chronic aortic dissection according to the DeBakey classification. Careful consideration is given to an uncomplicated course of the early and remote postoperative periods in the first-in-Russia patient to undergo surgery with the use of a new-type prosthesis. The control examinations carried out 6, 12, 28 and 39 months after the operation were unequivocally indicative of complete thrombosis of the false canal of the aorta at the level of the prosthesis and lack of signs of aortic diameter growth below the zone of the surgical intervention. An example of successful treatment of DeBakey type I aortic dissection may be regarded as an important stage in the development of more effective methods of surgery for the severe pathology concerned.

Purpose. To preliminarily evaluate the feasibility and accuracy of using rapid prototyping drill templates (RPDTs) for C1 lateral mass screw (C1-LMS) and C2 pedicle screw (C2-PS) placement. Methods. 23 formalin-fixed craniocervical cadaver specimens were randomly divided into two groups. In the conventional method group, intraoperative fluoroscopy was used to assist the screw placement. In the RPDT navigation group, specific RPDTs were constructed for each specimen and were used intraoperatively for screw placement navigation. The screw position, the operating time, and the fluoroscopy time for each screw placement were compared between the 2 groups. Results. Compared with the conventional method, the RPDT technique significantly increased the placement accuracy of the C2-PS ( p < 0.05). In the axial plane, using RPDTs also significantly increased C1-LMS placement accuracy ( p < 0.05). In the sagittal plane, although using RPDTs had a very high accuracy rate (100%) in C1-LMS placement, it was not statistically significant compared with the conventional method ( p > 0.05). Moreover, the RPDT technique significantly decreased the operating and fluoroscopy times. Conclusion. Using RPDTs significantly increases the accuracy of C1-LMS and C2-PS placement while decreasing the screw placement time and the radiation exposure. Due to these advantages, this approach is worth promoting for use in the Harms technique., Competing Interests: The authors declare that there are no competing interests regarding the publication of this paper.

Maintaining the hip center can improve the success of a total hip arthroplasty. A novel probe design, based on mating a toroid with a sphere, was used for kinematic measurements of the femoral head center and implant center in a pre-clinical study of hip joints. In an electromagnetically tracked implementation tested in a laboratory environment, the device measured a spherical center to within 1.2±0.2 mm in a technical validation. Applied to a plastic model of a cadaveric femur, the center of the femoral head was measured to 1.8±0.4 mm and the implant was measured to within 1.5±0.5 mm. Because leg length changes and offset changes in conventional hip arthroplasty can be as much as 16 mm, this device has relatively high accuracy that may improve implant localization for the hip.

Due to technical progress, the indication for total elbow arthroplasty could be expanded in recent years. As a result, the demand regarding functionality and mobility of the replaced joint has risen as well. Elbow arthroplasty has to be considered as technically demanding. Only with detailed knowledge of this surgical procedure and its possible intraoperative pitfalls can one provide the best possible results. In this instructional video we explain the implantation of the Latitude elbow prosthesis (Tornier) putting emphasis on the correct approach as well as implantation of the prosthesis and subsequent wound closure., (Georg Thieme Verlag KG Stuttgart · New York.)

Tip-apex distance is a well described method for assessment of screw placement in dynamic hip screw fixation of proximal femoral fracture. A distance of <25mm is associated with a significantly lower rate of cut out of the fixation device. Measurement is frequently performed retrospectively, although there has been no demonstration as to what accuracy the surgeon has of estimating tip-apex distance from image intensifier images, whilst scrubbed in theatre. Thirty-one clinicians working within orthopaedic departments were tested in their ability to identify adequacy of tip-apex distance on a series of image intensifier images. Level of seniority, awareness of the concept of tip-apex distance and use of the concept in clinical practice were each assessed. The accuracy in identifying the correct TAD was 82.5% in consultants, 83.8% in registrars and 71.1% in Senior house officers (SHO). The method was used in clinical practice by 50% of consultants, 89% of registrars and none of the SHOs., (Copyright © 2015 Elsevier Ltd. All rights reserved.)