The minimisation of errors incurred during the learning process is thought to enhance motor learning and improve performance under pressure or in multitasking situations. If this is proven in surgical skills learning, it has the potential to enhance the delivery of surgical education. We aimed to compare errorless and errorful learning using the high-speed burr.

Medical students (n=30) were recruited and allocated randomly to an errorless or errorful group. The errorless learning group progressively learnt tasks from easy to difficult on cedar boards simulating bone. The errorful learning group also progressed through the same tasks but not in order of difficulty.

Transfer tasks assessed students’ performance of cervical laminoplasty on saw bone models to assess their level of learning from previous stages. During transfer task 2, students completed the procedure under time pressure and in the presence of distractors, in order to simulate real-life stressors in theatre. Accuracy, precision and safety of the procedure were scored by expert opinions from spine surgeons blinded to the grouping of the participants.

Both errorless and errorful learners demonstrated improvements in performance with increasing amounts of practice (demonstrated by the decreased time taken for the task as well as improvement in accuracy of the cuts (depth, width and smoothness). The performance of both groups was not impaired by the incorporation of a secondary task which required participants to multitask. No statistically significant difference in performance was noted between the two groups.

In contrast to previous research, there was no significant difference between errorless or errorful learning to develop skills with a high-speed, side-cutting burr. In both groups, practical learning during the session has led to improvement in overall performance with the burr relevant to cervical laminoplasty.

The treatment of orthopedic implant infections is often difficult and complex, although the chances of successful treatment with a properly selected diagnostic, surgical and antibiotic treatment protocol have recently increased significantly. Surgical treatment is a key factor in the treatment of infections of orthopedic implants, and any errors in this respect often lead to worse clinical outcomes.

Surgical errors. The most important and frequent surgical errors include:

- conservative treatment of periprosthetic infections with antibiotics alone: successful treatment requires adequate surgical procedure combined with long-term antimicrobial Th that is active against biofilm microorganism. Without adequate surgical procedure just the suppression of symptoms is usually achieved, rather than eradication of the infection.

We present illustrative cases with each common surcical error combined with proper solution.

Treatment of PJI is a demanding procedure, the goal is a long-term pain-free functional joint, that can be achieved by eradication of the infection. For a successful clinical outcome an appropriate diagnostic, surgical and antimicrobial procedure for the individual patient has to be selected.

Purpose

Femoral component malrotation is a common cause for persisting symptoms and revision following total knee arthroplasty (TKA). There is ongoing debate about the most appropriate use of femoral landmarks to determine rotation. The Sulcus Line (SL, See Figure 1) is a three-dimensional curve produced from multiple points along the trochlear groove. Whiteside's Line, also known as the anteroposterior axis (APA), is derived from single anterior and posterior points. The purposes of the three studies presented are to i) assess the SL in a large clinical series, ii) demonstrate the effect of parallax error on rotational landmarks, and iii) assess the accuracy of a device which transfers a geometrically corrected SL onto the distal cut surface of the femur.

Background

There has been widespread interest in medical errors since the publication of ‘To Err is Human’ by the Institute of Medicine in 1999. The Patient Safety Committee of the American Academy of Orthopaedic Surgeons has compiled results of a member survey to identify trends in orthopaedic errors that would help direct quality assurance efforts.

INTRODUCTION

Wasted implants represent both an increased risk and cost to our healthcare system. In our institution, a sterilely packaged implant that is opened and not implanted is wasted in one out of 20 primary total knee replacement procedures. The cost of these wasted implants exceeds $1 million per year. We propose the introduction of a novel, computer based, e.Label and compatibility system to reduce implant-related medical errors and waste in total knee arthroplasty. We hypothesize that the implementation of this system will help reduce medical errors and wasted implants by improving and standardizing the visual markers and by ensuring that parts are compatible so that implant mismatches and inappropriate laterality are prevented.

Purpose

Surgical complications are common and frequently preventable. The introduction of the WHO Surgical Safety Checklist has improved surgical outcomes. WHO guidelines reduce, but do not prevent errors. Successful arthroplasty surgery requires strict infection control measures. We observed a single surgical team to see if errors caused by operating room personnel were covered by the WHO Checklist.

Glenoid baseplate orientation in reverse shoulder arthroplasty (RSA) influences clinical outcomes, complications, and failure rates. Novel technologies have been produced to decrease performance heterogeneity of low and high-volume surgeons. This study aimed to determine novice and experienced shoulder surgeon's ability to accurately characterise glenoid component orientation in an intra-operative scenario. Glenoid baseplates were implanted in eight fresh frozen cadavers by novice surgical trainees. Glenoid baseplate version, inclination, augment rotation, and superior-inferior centre of rotation (COR) offset were then measured using in-person visual assessments by novice and experienced shoulder surgeons immediately after implantation. Glenoid orientation parameters were then measured using 3D CT scans with digitally reconstructed radiographs (DRRs) by two independent observers. Bland-Altman plots were produced to determine the accuracy of glenoid orientation using standard intraoperative assessment compared to postoperative 3D CT scan results. Visual assessment of glenoid baseplate orientation showed “poor” to “fair” correlation to 3D CT DRR measurements for both novice and experienced surgeon groups for all measured parameters. There was a clinically relevant, large discrepancy between intra-operative visual assessments and 3D CT DRR measurements for all parameters. Errors in visual assessment of up to 19.2 degrees of inclination and 8mm supero-inferior COR offset occurred. Experienced surgeons had greater measurement error than novices for all measured parameters. Intra-operative measurement errors in glenoid placement may reach unacceptable clinical limits. Kinesthetic input during implantation likely improves orientation understanding and has implications for hands-on learning

Aim. Intramedullary osteomyelitis remains a challenge in the treatment of bone infections, requires organized, sequential and effective management to prevent its spread and subsequent recurrence. Errors are often made in the comprehensive treatment of this type of infection classified as type 1 of Cierny-Mader, where you can perform an insufficient treatment or in some cases perform very extensive and unnecessary bone resections. A rigorous protocol is proposed, by stages to achieve the total eradication of the infection and a surgical tactic that avoids diffusion of the infection or recurrences. Method. In the prospective case series study, 16 patients with type 1 intramedullary infection of Cierny Mader, diagnosed by radiology, TAC or MRI were included. The microbiological protocol is carried out, with the germ typing and the corresponding antibiogram, at least 3 samples of deep tissues, the biofilm and segments of dead bone are taken. In the surgical tactic, intramedullary sequestrations are resected, the intramedullary canal is cleaned by stages, initially in the most inflammatory focus detected, the medullary canal is accessed through a planned and defined bone window, with round edges to avoid fractures and allowing access To the flexible reamer and cleaning guides, an additional window is made that avoids the blood dissemination of the infection, the septic embolisms or the contamination of the underlying soft tissues. It is defined if it requires stabilization of the bone with internal or external devices, therapies are applied locally to avoid recolonization, using Bioglass or absorbable substitutes with selective antibiotic. The treatment is associated with intravenous antibiotic therapy between 2 and 6 weeks according to the type of germ and if it is multiresistant. It guarantees skin coverage and protection of structures at risk such as nerves, tendons and exposed bone. Results. Successful treatment results are obtained, infection eradication in 100% of cases, the healing of osteomyelitis is achieved by applying an integral management of the intramedullary canal Osteomyelitis and a complete protocol is established. Conclusions. The tactic and surgical technique applied in the integral management of intramedullary bone infection is essential to obtain definitive results in the eradication of bone infection. Care must be taken that the debridement is complete of the intramedullary canal and additionally, segmental or exaggerated resection of viable bone must be avoided, which survives and heals after the integral management of the infection with effective antibiotic therapy

Introduction. Navigated freehand cutting (NFC) technology simplifies bone cutting in laboratory trials by directly navigating implants and power tools [1]. Experiments showed that NFC bone cutting was faster than with conventional jigs. However, most delays occurred at the start of each cut [2]. Therefore, we further reduced starting times and gained more accuracy with a NaviPen and a ‘smart’ NaviPrinter [3]. There were used to physically mark a line on the bone surface indicating where each cut should start. (Fig. 1). Further gains are targeted with our introduction of the On-Tool Marker (OTM); a touch-less laser marking technology as a standalone device or mounted on the cutting instrument (e.g. on the saw). The OTM points the desired cut by projecting a laser image on the bone. That image (usually a line or cross) changes dynamically, so that for any given cut the line projection remains stationary on the bone regardless of the relative location of the device. Materials & Methods. The OTM is a standalone wireless module composed of three main parts: a small laser projector, electronics for control and communication (WiFi), and a tracking frame. It is navigated in real-time with a Polaris tracker. Software routines on a proprietary NFC system compute its relative position to the target and dynamically re-calculate the image parameters. Such parameters are sent to the OTM for processing, image generation, and projection (Fig. 2). Bandwidth and data integrity were evaluated through bench tests. To assess accuracy of the projection, a target planar cut was defined on a flat surface (a line drawn on grid paper pasted to a navigated board), and the NFC system was fed with this geometrical information. The OTM was moved within a volume of ∼50cm in diameter (distance to the target plane from 5cm to 50cm), and at various angles up to +/− 80° (in roll, pitch and yaw). The projected line should coincide with the target line on paper regardless of the relative positioning of the OTM. Errors (target vs. projected) were measured on the grid paper. Results. Well-defined lines were projected at a rate of 17fps. Projected lines remained within +/− 2 mm from the target (average ∼0mm). Errors, largely caused by a lag in the images, were unperceivable after a fraction of a second if OTM remained still. Among different colors tested, green was the most suitable, based on brightness and visibility (Fig. 3). Discussion and Conclusion. A ‘smart’ navigated laser marker was successfully created and tested. The limited refresh speed and lag was not much of a concern, as common use would not require fast motion. However, further work will focus on improving these, and devise solutions for projection on non-planar bone models. OTM would speed the surgery more as it saves the time to use the NaviPen or the NaviPrinter. We estimate this can reach 2–3 minutes based on some preliminary experiments we conducted and not reported here. Finally, OTM can help reduce the number of instruments in surgery even further (less inventory, less sterilization, less cost and less worries)

Introduction. Soft tissue artefact (STA) affects the kinematics retrieved with skin marker-based motion capture, and thus influences the outcomes of biomechanical models that rely on such kinematics. To date, compensation for STA remains an unsolved challenge due to its complexity. Factors include its dependency on subject, on motion activity and on skin-marker configuration, its non-linearity over the movement cycle, and the scarcity of reference in-vivo estimations. The objective of this study was extending the existing knowledge of the effects of STA on the kinematics of the hip joint and on the hip joint center location, by quantifying them for a sample total hip arthroplasty (THA) population, for a broader range of activities of daily living (ADLs). Methods. Four activities of daily living (overground gait, stairs descent, chair rise and putting on socks) were measured simultaneously with optical motion capture (MC) at 100 Hz and with a movable single-plane video-fluoroscopy system (VF) at 25 Hz, for fifteen patients with successful total hip arthroplasty (THA). The joint segment positions were computed by least-square fitting for MC and by semi-automatic 2D/3D registration for VF. Anatomical coordinate systems were defined for each joint segment based on skin markers location at a reference standing position. Errors induced by STA on the retrieved joint motion were computed as the difference between MC-based kinematics and the reference VF-based kinematics. Statistical analysis was carried out to determine the whether the differences between the kinematics obtained with the two methods were significant. Results. MC underestimated the ROM of the hip joint for all activities. The ROM for the flexion-extension was underestimated by on average 4.1°, 6.5°, 8.0° and 6.9° for gait, stair decent, chair rise and putting on socks respectively. Overall, during dynamic activities the hip joint was less flexed, more adducted and more internally rotated as retrieved using MC, compared to VF. The flexion angle was underestimated by MC during late stance phase and early swing phase for both gait and stairs descent. The internal rotation of the hip was overestimated by MC throughout the whole cycle of each activity. MC error for the thigh was larger than the MC error for the pelvis. MC errors above 1 cm were observed for the location of the hip joint center, with higher values for the cranial-caudal direction. Discussion. Reduced ROM supports the notion that skin-sliding is a major contributor to STA. The underestimation of hip flexion appeared to be positively correlated to the degree of flexion. Larger skin deformation and sliding occurring for the thigh at higher hip flexion angles may produce the observed patterns of MC error for FE. The CC error was possibly due to inertial effects, and was more pronounced for the stair descent due to larger vertical movement and acceleration. This study led further bases for the activity-dependent correction of STA. This has the potential of improving the accuracy of motion capture and boosting its use for motion analysis as opposite to video-fluoroscopy techniques, which deliver radiation dose to the subjects

Introduction. The Intellijoint HIP system is a mini-optical navigation system designed to intraoperatively assist with cup orientation, leg length and offset in total hip replacement (THR). As with any imageless navigation system, acquiring the pelvic reference frame intraoperatively requires assumptions. The system does however have the ability to define the native acetabular orientation intra-operatively by registering 3-points along the bony rim. In conjunction with a pre-operative CT scan, the authors hypothesised that this native acetabular plane could be used as an intraoperative reference to achieve a planned patient-specific cup orientation. Method. Thirty-eight THR patients received preoperative OPS. TM. dynamic planning (Optimized Ortho, Sydney). On the pre-operative 3D model of each patient's acetabulum, a 3-point plane was defined by selecting recognisable features on the bony rim. The difference in inclination and anteversion angles between this native 3-point reference plane and the desired optimal orientation was pre-operatively calculated, and reported to the surgeon as “adjustment angles”. Intraoperatively, the surgeon tried to register the same 3-points on the bony rim. Knowing the intraoperative native acetabular orientation, the surgeon applied the pre-calculated adjustment angles to achieve the planned patient specific cup orientation. All patients received a post-operative CT scan at one-week and the deviation between planned and achieved cup orientation was measured. Additionally, the cup orientation that would have been achieved if the standard Intellijoint pelvic acquisition was performed was retrospectively determined. Results. The absolute mean inclination deviation from plan of the 3-point rim method was 5.6° (0.0° to 16.7°). The absolute mean anteversion deviation from plan of the 3-point rim method was 2.7° (0.1° to 9.5°). This constituted 90% within 10° of the desired patient-specific target. All anteversion measurements were within 10°, with 90% within 5°. The retrospective analysis on what would have been achieved if the standard pelvic acquisition was used, showed that the absolute mean inclination deviation from plan would have been 4.0° (0.0° to 14.2°) and the absolute mean anteversion deviation would have been 6.7° (0.1° to 24.1°). Only 74% of cups would have been within 10° of the desired target. Conclusions. Using the native acetabular orientation as a reference plane for delivering a patient-specific cup orientation showed promising preliminary results. Errors in inclination were significantly larger than anteversion. More points on the rim could reduce this error

The National Joint Registry (NJR) was set up by the Department of Health to collect information on all joint replacements. The NJR data is externally validated against nationally collated Hospital Episode Statistics (HES). Errors associated with the use of HES data have been widely documented. We sought to explore the accuracy of the NJR data, for a single surgeon, against a prospectively collected personal logbook. The NJR and logbook were compared over a 3-year period (01/07/2009 to 30/06/2012). Total procedure recorded in the personal logbook was 684 and in the NJR was 681. TKR in personal log book was 304 and in NJR 316, revision knee's in personal logbook 45 and in NJR 36, THR 274 in personal logbook and 271 in NJR, revision hip procedures in personal logbook 64 and 58 in NJR. Whilst the total number of procedures captured correlates closely (681 vs 684) there is more variation with the different individual procedures. This may be due to the addition of 11% of HES data used for this time period by the NJR as it is known to be inaccurate. This therefore demonstrates the importance of maintaining your own accurate records

Implant alignment in knee arthroplasty has been identified as critical factor for a successful outcome. Human error during the registration process for imageless computer navigation knee arthroplasty directly affects component alignment. This cadaveric study aims to define the error in the registration of the landmarks and the resulting error in component alignment. Five fresh frozen cadaveric limbs including the hemipelvis were used for the study. Five surgeons performed the registration process via a medial parapatellar approach five times. In order to identify the gold standard point, the soft tissues were stripped and the registration was repeated by the senior author. Errors are presented as mm or degrees from the gold standard registration. The error range in the registration of the femoral centre in the coronal plane was 6.5mm laterally to 5.0mm medially (mean: −0.1, SD: 2.7). This resulted in a mechanical axis error of 5.2 degrees valgus to 2.9 degrees varus (mean: 0.1, SD: 1.1). In the sagittal plane this error was between −1.8 degrees (extension) and 2.7 degrees (flexion). The error in the calculation of the tibial mechanical axis ranged from −1.0 (valgus) to 2.3 (varus) degrees in the coronal plane and −3.2 degrees of extension to 1.3 degrees of flexion. Finally the error in calculating the transepicondylar axis was −11.2 to 6.3 degrees of internal rotation (mean: −3.2, SD: 3.9). The error in the registration process of the anatomical landmarks can result in significant malalignment of the components. The error range for the mechanical axis of the femur alone can exceed the 3 degree margin that has been previously been associated with implant longevity. The technique during the registration process is of paramount importance for image free computer navigation. Future research should be directed towards simplifying this process and minimizing the effect of human error

Inserting screws into the vertebral pedicles is a challenging step in spinal fusion and scoliosis surgeries. Errors in placement can lead to neurological complications. The more experienced the surgeon, the better the accuracy of the screw placement. A physical training system would provide residents with the feel of performing pedicle cannulation before operating on a patient. The proposed system consists of realistic bone models mimicking the geometry and material properties of typical patients, coupled with a force feedback probe. The purpose of the present study was to determine the forces encountered during pedicle probing to aid in the development of this training system. We performed two separate investigations: [1] 15 participants (9 expert surgeons, 3 fellows and 3 residents) were asked to press a standard pedicle awl three times onto a mechanical scale, blinded to the force, demonstrating what force they would apply during safe pedicle cannulation and during unsafe cortical breach; [2] three experienced surgeons used a standard pedicle awl fitted with a one-degree of freedom load cell to probe selected thoracolumbar vertebrae of eight cadaveric specimens to measure the forces required during pedicle cannulation and deliberate breaching. A total of 42 pedicles were tested. Both studies had wide variations in the results, but were in general agreement. Cannulation (safe) forces averaged approximately 90 N (20 lb) whereas breach (unsafe) forces averaged approximately 135–155 N (30–35 lb). The lowest average forces in the cadaveric study were for pedicle cannulation, averaging 86 N (range, 23–125 N), significantly lower (p<0.001) than for anterior breach (135 N; range, 80–195 N); medial breach (149 N; range, 98–186 N) and lateral breach (157 N; range, 114–228 N). There were no significant differences between the breach forces (p>0.1). Cannulation forces were on average 59% of the breach forces (range, 19–84%) or conversely, breach forces were 70% higher than cannulation forces. To our knowledge, these axial force data are the first available for pedicle cannulation and breaching. A large range of forces was measured, as is experienced clinically. Additional testing is planned with a six-degree-of-freedom load cell to determine all of the forces and moments involved in cannulation and breaching, throughout the thoracolumbar spine. These results will inform the development of a realistic bone model as well as a breach prediction algorithm for a physical training system for spine surgery

INTRODUCTION. Unicompartmental knee arthroplasty (UKA) can achieve excellent clinical and functional results for patients suffering from single compartment osteoarthritis. However, UKA is considered to be more technically challenging to perform, and malalignment of the implant components has been shown to significantly contribute to UKA failures. The purpose of this investigation was to determine the clinically realized accuracy of UKA component placement using surgical navigation and dynamically referenced tactile-robotics. METHODS. Pre-op CT, post-op CT, and surgical plan were available for 22 knees out of the first 45 procedures performed using a new tactile-guided robotic system. 3D component placement accuracy was assessed by comparing the pre-operative plan with the post-operative implant placement (desired versus actual). Bone and implant models were obtained from postoperative CT scans taken immediately following the surgery. A 3D to 3D iterative closest point registration procedure was performed and the measured implant position was directly compared to the preoperative plan. Errors were assessed as single axis root-mean-square (RMS) entities. RESULTS. Femoral component RMS placement errors averaged 1.4 mm/2.6° along any single axis. Tibial component RMS placement errors averaged 1.18 mm/2.14° along any single axis. CONCLUSION. Using traditional manual instruments, Cobb et al. found average RMS errors of 2.20mm/5.48°. Using the robotic approach with bones fixed, Cobb et al. reported RMS errors of 1.11 mm/2.5°, directly comparable to our results with bones moving freely during surgery. Varus/valgus femoral component alignment and posterior tilt of the tibial component are within the accepted range to prevent excessive edge loading, leading to tibial plateau collapse and/or excessive wear. Dynamically-referenced tactile robotics provide a new tool to accurately prepare bone with minimally invasive approaches. Our results suggest excellent UKA implant placement accuracy can be achieved, comparable to that demonstrated for statically referenced tactile robotics. The patients were the first group from a single surgeon using this technique, suggesting good implant alignment is achieved in what normally would be considered a learning phase. Finally, these patients were treated with the first approved version of this new tool, suggesting further refinement of this robotic technology will enhance the accuracy and usability of this tool

INTRODUCTION. Over the last twenty years, image-guided interventions have been greatly expanded by the advances in medical imaging and computing power. A key step for any image-guided intervention is to find the image-to-patient transformation matrix, which is the transformation matrix between the preoperative 3D model of patient anatomy and the real position of the patient in the operating room. In this work, we propose a robust registration algorithm to match ultrasound (US) images with preoperative Magnetic Resonance (MR) images of the Humerus. MATERIALS AND METHODS. The fusion of preoperative MR images with intra-operative US images is performed through an NDI Spectra® Polaris system and a L12-5L60N TELEMED® ultrasound transducer. The use of an ultrasound probe requires a calibration procedure in order to determine the transformation between an US image pixel and its position according to a global reference system. After the calibration step, the patient anatomy is scanned with US probe. US images are segmented in real time in order to extract the desired bone contour. The use of an optical measurement system together with trackers and the previously-computed calibration matrix makes it possible to assign a world coordinate position to any pixel of the 2D US image. As a result, the set of US pixels extracted from the images results in a cloud of 3D points which will be registered with the 3D Humerus model reconstructed from MR images. The proposed registration method is composed of two steps. The first step consists of US 3D points cloud alignment with the 3D bone model. Then, the second step performs the widely-known Iterative Closest Point (ICP) algorithm. In order to perform this, we define the coordinate system of both the 3D Humerus model and the US points cloud. The frame directions correspond to the directions of the principal axes of inertia calculated from the matrices of inertia of both the preoperative 3D model and the US data obtained intra-operatively. Then, we compute the rotation matrix to estimate the transformation between the two coordinate systems previously calculated. Finally the translation is determined by evaluating the distance between the mass centres of the two 3D surfaces. RESULTS. In order to evaluate the performance of this registration method in terms of precision and accuracy, we performed the US/MRI fusion on 8 patients. The evaluation criterion used for the validation step was the fiducial registration error (FRE) estimation based on 8 anatomic fiducials detected on the Humerus of the patient. The mean, standard deviation, minimum and maximum values of the 8 Fiducial Registration Errors were 4.34, 2.20, 2.81 and 9.48 mm, respectively. DISCUSSIONS. In this work, we propose a robust registration method of MR and US data. Thanks to the optical system, this fusion will allow us for example to guide and assist surgeons in the positioning of the radiofrequency probe for bone tumor ablation. In addition to the fact that it is completely automatic, the proposed image-to-patient registration method is minimally invasive

Aims

The Precice intramedullary limb-lengthening system has demonstrated significant benefits over external fixation lengthening methods, leading to a paradigm shift in limb lengthening. This study compares outcomes following antegrade and retrograde femoral lengthening in both adolescent and adult patients.