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Background The anteroposterior (ap) radiograph of the pelvis is decisive in the diagnosis of different pathologies of the hip joint. Technical advantages have reduced the radiation dose of pelvic CT to levels comparable to radiographs. The purpose of this study was to validate if standard radiographic parameters (lateral center edge angle, medial center edge angle, acetabular index, acetabular arc, extrusion index, crossover sign and posterior wall sign) can accurately be determined on radiograph-like projections reconstructed from the CT dataset pre- and postoperatively. Methods A consecutive series of patient with symptomatic dysplasia of the hip and a full radiologic workup (radiographs and CT scan pre- and postoperatively) who underwent periacetabular osteotomy were included. Standard radiographic parameters were compared between radiographs and radiograph-like projections by two authors pre- and postoperatively. Results A total of 16 hips (32 radiographs/32 radiograph-like projections) were included in the study. No significant difference was found between the radiographs and radiograph-like images for all parameter for both examiners. ICC between radiograph and radiograph-like projections for all investigated parameters showed good to excellent reliability (0.78–0.99) pre- and postoperatively. Conclusion Radiograph-like projections show comparable results to radiographs with regard to the important investigated parameters (lateral center edge angle, medial center edge angle, acetabular index, acetabular arc, extrusion index, crossover sign and posterior wall sign). Thus, ultra-low-dose CT scans may reduce the need for conventional radiographs in pre- and postoperative analyses of 3-dimensional hip pathologies in the future, as the advantages increasingly outweigh the disadvantages.

Introduction Due to multiplanar deformities of the hip, total hip arthroplasty (THA) for sequelae of Legg–Calvé–Perthes disease (LCPD) is often technically demanding. This study aimed to compare the clinical and radiographic outcomes of patients with sequelae of LCPD undergoing THA through the direct anterior approach (DAA) and non-anterior approaches to the hip. Methods All patients with sequelae of LCPD who underwent primary THA between 2004 and 2018 (minimum follow-up: 2 years) were evaluated and separated into two groups: THA through the DAA (Group AA), or THA through non-anterior approaches to the hip (Group non-AA). Furthermore, a consecutive control group of patients undergoing unilateral THA through the DAA for primary hip osteoarthritis (Group CC) was retrospectively reviewed for comparison. Results Group AA comprises 14 hips, group non-AA 17 hips and group CC 30 hips. Mean follow-up was 8.6 (± 5.2; 2–15), 9.0 (± 4.6; 3–17) and 8.1 (± 2.2; 5–12) years, respectively. At latest follow-up, Harris Hip Score was 90 (± 20; 26–100), 84 (± 15; 57–100), and 95 (± 9; 63–100) points, respectively. Overall, 6 patients treated for LCPD (each 3 patient in the AA and non-AA group) developed postoperative sciatic nerve palsy, of which only one was permanent. Complication-related revision rate at the latest follow-up was 15% in the AA-group and 25% in the non-AA group, respectively. Conclusion THA through the DAA might be a credible option for the treatment of sequelae of LCPD with comparable complication rates and functional outcomes to non-anterior approaches.

High-grade patellofemoral dysplasia is often associated with concomitant axial and frontal leg malalignment. However, curvature of the femur and sagittal flexion of the trochlea has not yet been studied in patellofemoral dysplastic knees. The aim of the study was to quantify the femoral curvature and sagittal flexion of the trochlea in both high-grade patellofemoral dysplastic and healthy knees.A retrospective case-control study matched 19 high-grade patellofemoral dysplastic knees (Dejour types C and D) with 19 healthy knees according to sex and body mass index. Three-dimensional (3D) femoral curvature and sagittal trochlea flexion were analysed. To analyse femoral curvature, the specific 3D radius of curvature (ROC) was calculated. Trochlear flexion was quantified through the development of the trochlea flexion angle (TFA), which is a novel 3D measurement in relation to the anatomical and mechanical femur axis and is referred to as 3D TFAOverall ROC was significantly smaller in dysplastic knees, compared with the control group [898.4 ± 210.8 mm (range 452.9-1275.1 mm) vs 1308.4 ± 380.5 mm (range 878.3-2315.8 mm), p 0.001]. TFA was significantly higher in dysplastic knees, compared with the control group, for 3D TFAHigh-grade patellofemoral dysplastic knees demonstrated increased femoral curvature and sagittal flexion of the trochlea, compared with healthy knees. The ROC and newly described TFA allowed the quantification of the sagittal femoral deformity. TFA and ROC should be incorporated in future deformity analysis to investigate their potential as a target for surgical correction.Level III.

Aim: The purpose of this study was to investigate the greater trochanter’s (GT) behaviour in simulated subtrochanteric osteotomy. Materials and methods: Measurement of functional and anatomical femoral torsion, and position of the GT and lesser trochanter was performed using 3-dimensional (3D) surface models of 100 cadaveric femora. Femoral torsion between 2° and 22° was defined as normal, femora with 22° of femoral torsion were assigned to the low- and high-torsion group. Subtrochanteric osteotomy was simulated to normalise torsional deformities to 12°. Results: With subtrochanteric osteotomy, functional torsion was simultaneously corrected while adjusting anatomical torsion ( R2 = 0.866, p 2 = 0.946; p Conclusions: Subtrochanteric osteotomy for femoral maltorsion reliably adjusts anatomical and functional torsion, but also results in a ±1 cm AP shift of the GT per 10° of torsional correction. However, this effect of the procedure is most likely not clinically relevant in relation to hip abductor performance.

Background Inaccurately scaled radiographs for total hip arthroplasty (THA) templating are a source of error not recognizable to the surgeon and may lead to inaccurate reconstruction and thus revision surgery or litigation. Planning based on computed tomography (CT) scans is more accurate but associated with higher radiation exposure. The aim of this study was (1) to retrospectively assess the scaling deviation of pelvic radiographs; (2) to prospectively assess the feasibility and the radiation dose of THA templating on radiograph-like images reconstructed from a tin-filtered ultra-low-dose CT dataset. Methods 120 consecutive patients were retrospectively analyzed to assess the magnification error of our current THA templates. 27 consecutive patients were prospectively enrolled and a radiographic work-up in the supine position including a new tin-filtered ultra-low-dose CT scan protocol was obtained. THA was templated on both images. Radiation dose was calculated. Results Scaling deviations between preoperative radiographs and CT of ≥ 5% were seen in 25% of the 120 retrospectively analyzed patients. Between the two templates trochanter tip distance differed significantly (Δ2.4 mm, 0–7 mm, p = 0.035)), predicted femoral shaft size/cup size was the same in 45%/41%. The radiation dose of the CT (0.58 mSv, range 0.53–0.64) was remarkably low. Conclusion Scaling deviations of pelvic radiographs for templating THA may lead to planning errors of ≥ 3 mm in 25% and ≥ 6 mm in 2% of the patients. 2-D templating on radiograph-like images based on tin-filtered ultra-low-dose CT eliminates this source of error without increased radiation dose. Level of evidence Retrospective and prospective comparative study, Level III.

The relationship between anterior pelvic tilt and overall sagittal alignment has been well-described previously. However, the relationship between pelvic tilt, frontal, and axial leg alignment remains unclear. The aim of the study was to analyze the relationship between pelvic tilt and frontal and axial leg alignment in healthy subjects.Thirty healthy subjects (60 legs) without prior surgery underwent standing biplanar long leg radiograph. Pelvic parameters (pelvic tilt, pelvic incidence, sacral slope), hip-knee-ankle angle (HKA), femoral antetorsion and tibial torsion were measured using SterEOS (EOS Imaging) software. EOS was acquired with the feet directing straight anteriorly, which corresponds to a neutral foot progression angle (FPA). The influence of HKA, femoral antetorsion, tibial torsion and gender on pelvic tilt was analyzed in a univariate correlation and multiple regression model.Sixteen female subjects and 14 male subjects with a mean age of 27.1 years ± 10 (range 20-67) were included. HKA, femoral antetorsion, and tibial torsion correlated with anterior pelvic tilt in univariate analysis (all p 0.05). Anterior pelvic tilt increased 1.1° (95% CI: 0.7 to 1.5) per 1° of knee valgus (p 0.001) and 0.5° (95% CI: 0.3 to 0.7) per 1° of external tibial torsion (p 0.001). Overall, linear regression model fit explained 39% of variance in pelvic tilt by the HKA, femoral antetorsion and tibial torsion (RValgus alignment and increasing tibial torsion demonstrated a weak correlation with an increase in anterior pelvic tilt in healthy subjects when placing their feet anteriorly. The relationship between frontal, axial leg alignment and pelvic tilt needs to be considered in patients with multiple joint disorders at the hip, knee and spine. Alteration of the frontal, or rotational profile after realignment surgery or by implant positioning might influence the pelvic tilt when the FPA is kept constant.

Introduction Complete surgical resection remains the mainstay of the treatment of soft tissue sarcomas. Intraoperative positioning of the patient is dictated by tumor location, whereas preoperative imaging is always performed in the supine position. The effect of changing the patient position on the exact location of the tumor with regard to neurovascular structures and bone is unknown. Material and methods Two fresh frozen cadavers (pelvis and legs) were thawed and warmed. Three standardized tumor models were implanted in the thigh and calf. MR/CT images of the cadavers were obtained sequentially in four different patient positions. The minimal distance of each “tumor” to neurovascular structures was measured on axial MR images and the 3D shift of the center of the tumor to the bone was measured after segmentation of the CT images. Results A significant difference of the minimal distance of the “tumor” to the femoral artery (P = 0.019/0.023) and a significantly greater number of deviations of more than 5mm/10 mm in the thigh between the supine position and the other positions compared to two supine positions (p = 0.027/0.028) were seen. The center of the “tumor” compared to the bone shifted significantly in the thigh (P Conclusion Obtaining images in the same patient position as the planned tumor resection may become particularly relevant if computer assisted surgery, which is based on preoperative imaging, is introduced into soft tissue sarcoma surgery as the patient position significantly influences the spatial position of the tumor.

The purpose was to study if (1) diurnal changes occur in the entire spine and if (2) intervertebral discs (IVDs) of weightlifters (WL) have decreased baseline T2-values in the morning as well as (3) increased diurnal changes throughout the day. This prospective cohort study investigated healthy volunteers between 2015 and 2017. WL were required to have participated in weightlifting ≥ 4×/week for ≥ 5 years, while non-weightlifters (NWL) were limited to

Purpose Recent data suggest that individual morphologic factors should be respected to restore preoperative patellofemoral alignment and thus reduce the likelihood of anterior knee pain. The goal of this study was to investigate the effect of excessive femoral torsion (FT) on clinical outcome of TKA. Methods Patients who underwent TKA and complete preoperative radiographic evaluation including a long-leg radiograph and CT scan were included. 51 patients showed increased FT of > 20° and were matched for age/sex to 51 controls (FT Results There was no significant difference between clinical scores two years after surgery between patients with normal and excessive FT (n.s.). Kujala score was 64.3 ± 16.7 versus 64.8 ± 14.4 (n.s.), and patellofemoral score for TKA was 74.3 ± 21 versus 78.5 ± 20.7 (n.s.) for increased FT group and control group, respectively. There was no correlation between preoperative FT and clinical scores. Other radiographic parameters were similar between both groups. No correlations between clinical outcomes and preoperative/postoperative frontal leg axis or total leg axis correction were found (n.s.). Conclusion If the leg axis deformity is corrected to a roughly neutral alignment during cemented TKA, including patellar denervation, then excessive FT was not associated with patellofemoral pain or instability. Level of evidence. Prospective comparative study, level II.

Background: AR based navigation of spine surgeries may not only provide accurate surgical execution but also operator independency by compensating for potential skill deficits. “Direct” AR-navigation, namely superposing trajectories on anatomy directly, have not been investigated regarding their accuracy and operator's dependence.Purpose of this study was to prove operator independent reliability and accuracy of both AR assisted pedicle screw navigation and AR assisted rod bending in a cadaver setting. Methods: Two experienced spine surgeons and two biomedical engineers (laymen) performed independently from each other pedicle screw instrumentations from L1-L5 in a total of eight lumbar cadaver specimens (20 screws/operator) using a fluoroscopy-free AR based navigation method. Screw fitting rods from L1 to S2-Ala-Ileum were bent bilaterally using an AR based rod bending navigation method (4 rods/operator). Outcome measures were pedicle perforations, accuracy compared to preoperative plan, registration time, navigation time, total rod bending time and operator's satisfaction for these procedures. Results: 97.5% of all screws were safely placed (

The purpose of this study was to investigate if one level of corrective femoral osteotomy (subtrochanteric or supracondylar) bears an increased risk of unintentional implications on frontal and sagittal plane alignment in a simulated clinical setting.Out of 100 cadaveric femora, 23 three-dimensional (3-D) surface models with femoral antetorsion (femAT) deformities ( 22° or 2°) were investigated, and femAT normalized to 12° with single plane rotational osteotomies, perpendicular to the mechanical axis of the femur. Change of the frontal and sagittal plane alignment was expressed by the mechanical lateral distal femoral angle (mLDFA) and the posterior distal femoral angle (PDFA), respectively. The influence of morphologic factors of the femur [centrum-collum-diaphyseal (CCD) angle and antecurvatum radius (ACR)] were assessed. Furthermore, position changes of the lesser (LT) and greater trochanters (GT) in the frontal and sagittal plane compared to the hip centre were investigated.Mean femoral derotation of the high-antetorsion group (n = 6) was 12.3° (range 10-17°). In the frontal plane, mLDFA changed a mean of 0.1° (- 0.06 to 0.3°) (n.s.) and - 0.3° (- 0.5 to - 0.1) (p = 0.03) after subtrochanteric and supracondylar osteotomy, respectively. In the sagittal plane, PDFA changed a mean of 1° (0.7 to 1.1) (p = 0.03) and 0.3° (0.1 to 0.7) (p = 0.03), respectively. The low-antetorsion group (n = 17) was rotated by a mean of 13.8° (10°-23°). mLDFA changed a mean of - 0.2° (- 0.5° to 0.2°) (p 0.006) and 0.2° (0-0.5°) (p 0.001) after subtrochanteric and supracondylar osteotomy, respectively. PDFA changed a mean of 1° (- 2.3 to 1.3) (p 0.01) and 0.5° (- 1.9 to 0.3) (p 0.01), respectively. The amount of femAT correction was associated with increased postoperative deviation of the mechanical leg axis (p 0.01). Using multiple regression analysis, no other morphological factors were found to influence mLDFA or PDFA. Internal rotational osteotomies decreased the ischial-lesser trochanteric space by 5 mm in both the frontal and sagittal plane (p 0.001).In case of femAT correction of ≤ 20°, neither subtrochanteric nor supracondylar femoral derotational or rotational osteotomies have a clinically relevant impact on frontal or sagittal leg alignment. A relevant deviation in the sagittal (but not frontal plane) might occur in case of a 25° subtrochanteric femAT correction.IV.

The role of increased femoral antetorsion (femAT) as a contributor to patellofemoral (PF) osteoarthritis (OA) is unknown. The purpose of this study was to investigate whether increased femAT was associated with advanced cartilage degeneration in the lateral PF joint.Patients who underwent complete radiographic workup for surgical intervention due to OA in any knee joint compartment were included. Cartilage morphology according to the International Cartilage Repair Society (ICRS) cartilage lesion classification system in the PF joint, femoral and tibial torsion, frontal leg axis, and tibial tuberosity-trochlear groove (TT-TG) distance were assessed. Increased femAT was defined as 20° according to previous reports.A total of 144 patients were included. Ninety-seven patients had a femAT of 20° and 45 of 20°. A significant odds ratio (OR) was found for lateral retropatellar (OR 3.5; p = 0.02) ICRS grade 3 and 4 cartilage degeneration and increased femAT ≥ 20°. In the medial PF compartment, increased femAT had an inverse effect (OR 0.16; p = 0.01). No significant ORs were found for TT-TG distance, tibial torsion, or leg axis. The lateral retropatellar ICRS grade showed a linear correlation to increased femAT values. In valgus knees, isolated lateral PF OA had an even more pronounced correlation to increased femAT (p = 0.004).Increased femAT showed higher grades of lateral retropatellar cartilage degeneration, which was even more pronounced in valgus knees.Cohort study: Level III.

PurposePathological tibial torsion is known to negatively influence the functionality of the lower extremity, and therefore, its assessment might play an important role. While 3D imaging is used for many examinations of the musculoskeletal system, for the determination of tibial torsion no 3D measurement technique has been available so far. We developed a 3D measurement method and assess its interobserver reliability as well as its correlation with standard 2D measurement methods.MethodsCT scans of 82 tibiae in 79 patients with a mean age of 41 years were included. A novel 3D measurement technique was developed and applied. Measurements were compared with two frequently used 2D measurement methods. ICC (intraclass correlation coefficient) for the new technique was determined and compared to the 2D measurement method. Furthermore, differences between left and right legs as well as between males and females were assessed.ResultsThe ICC for the 2D methods was 0.917 and 0.938, respectively. For the 3D measurements, ICCs were calculated to be 0.954 and 0.950. Agreement between 2 and 3D methods was moderate to good with ICCs between 0.715 and 0.795. Torsion values for left and right legs did not differ significantly in 2D and in 3D (26.2 vs 28.5° and 27.2 vs. 25.9°). The same is true for the differences between male and female in 2D and 3D (26.2 vs. 29.6° and 25.0 vs. 31.2°).ConclusionThe newly developed 3D measurement technique shows a high intraclass agreement and offers an applicable opportunity to assess the tibial torsion three-dimensionally.

Background Treating osteoarthritis in elderly patients with THA is very successful. However, surgeons hesitate to recommend THA in younger patients. The spectrum of etiologies for end stage hip disease in the younger population is diverse and therefore different courses may be assumed. Our objective was to evaluate THA revision rate within a minimum follow-up period of 10 years in young patients and to analyze the difference between different primary diagnoses. Methods We included 144 consecutive hips in 127 patients younger than 40 years, who received a primary THA from 01/1996 to 12/2007. Operative reports, clinical and radiographic documentation were reviewed to determine primary diagnosis, prior hip surgery, component specifications and revision surgery. 111 hips in 97 patients were available for outcome analysis with a minimum follow-up of 10 years. Results The mean age was 33 years (range 15–40 years) at the time of the index THA, 68 patients were female and 59 were male. Ten years revision rate on the prosthetic components was 13%. The most common primary diagnosis was DDH. DDH was associated with a risk of 17% for requiring a reoperation on the prosthetic components because of mechanical fatigue and therefore, significantly higher than for any other primary diagnosis (p = 0.005). Conclusion THA in young patients is associated with a high revision rate of 13% in 10 years. 17% of patients with DDH required revision surgery for mechanical fatigue within 10 years, which was significantly higher than for any other primary diagnosis (1.2%, OR 16.8).

Augmented reality (AR)-based surgical navigation may offer new possibilities for safe and accurate surgical execution of complex osteotomies. In this study we investigated the feasibility of navigating the periacetabular osteotomy of Ganz (PAO), known as one of the most complex orthopedic interventions, on two cadaveric pelves under realistic operating room conditions. Preoperative planning was conducted on computed tomography (CT)-reconstructed 3D models using an in-house developed software, which allowed creating cutting plane objects for planning of the osteotomies and reorientation of the acetabular fragment. An AR application was developed comprising point-based registration, motion compensation and guidance for osteotomies as well as fragment reorientation. Navigation accuracy was evaluated on CT-reconstructed 3D models, resulting in an error of 10.8 mm for osteotomy starting points and 5.4° for osteotomy directions. The reorientation errors were 6.7°, 7.0° and 0.9° for the x-, y- and z-axis, respectively. Average postoperative error of LCE angle was 4.5°. Our study demonstrated that the AR-based execution of complex osteotomies is feasible. Fragment realignment navigation needs further improvement, although it is more accurate than the state of the art in PAO surgery., Applied Sciences, 11 (3), ISSN:2076-3417

In this work, we propose a method utilizing tool-integrated vibroacoustic measurements and a spatio-temporal learning-based framework for the detection of the insertion endpoint during femoral stem implantation in cementless Total Hip Arthroplasty (THA). In current practice, the optimal insertion endpoint is intraoperatively identified based on surgical experience and dependent on a subjective decision. Leveraging spectogram features and time-variant sequences of acoustic hammer blow events, our proposed solution can give real-time feedback to the surgeon during the insertion procedure and prevent adverse events in clinical practice. To validate our method on real data, we built a realistic experimental human cadaveric setup and acquired acoustic signals of hammer blows during broaching the femoral stem cavity with a novel inserter tool which was enhanced by contact microphones. The optimal insertion endpoint was determined by a standardized preoperative plan following clinical guidelines and executed by a board-certified surgeon. We train and evaluate a Long-Term Recurrent Convolutional Neural Network (LRCN) on sequences of spectrograms to detect a reached target press fit corresponding to a seated implant. The proposed method achieves an overall per-class recall of \(93.82\pm 5.11\%\) for detecting an ongoing insertion and \(70.88\pm 11.83\%\) for identifying a reached target press fit for five independent test specimens. The obtained results open the path for the development of automated systems for intra-operative decision support, error prevention and robotic applications in hip surgery.

Computer-assisted orthopedic interventions require surgery planning based on patient-specific three-dimensional anatomical models. The state of the art has addressed the automation of this planning process either through mathematical optimization or supervised learning, the former requiring a handcrafted objective function and the latter sufficient training data. In this paper, we propose a completely model-free and automatic surgery planning approach for femoral osteotomies based on Deep Reinforcement Learning which is capable of generating clinical-grade solutions without needing patient data for training. One of our key contributions is that we solve the real-world task in a simulation environment tailored to orthopedic interventions based on an analytical representation of real patient data, in order to overcome convergence, noise, and dimensionality problems. An agent was trained on simulated anatomy based on Proximal Policy Optimization and inference was performed on real patient data. A qualitative evaluation with expert surgeons and a complementary quantitative analysis demonstrated that our approach was capable of generating clinical-grade planning solutions from unseen data of eleven patient cases. In eight cases, a direct comparison to clinical gold standard (GS) planning solutions was performed, showing our approach to perform equally good or better in 80% (surgeon 1) respectively 100% (surgeon 2) of the cases.

Background Preoperative templating in total hip arthroplasty (THA) is mandatory to achieve appropriate offset and leg length equality. However, templating methods using the contralateral hip might be susceptible to errors resulting from side-differences in the femoral morphology. The distance of the lesser trochanter to the femoral head center (LTFHD) is a frequently used reference parameter for preoperative planning and intraoperative validation during THA. However, currently no three-dimensional (3D) analysis of side differences of the LTFHD exists. Methods Using Computer tomography (CT)-based surface models from 100 paired femora (50 cadavers), side-to-side asymmetry of the LTFHD, femoral length, femoral head diameter (FHD) and femoral antetorsion were analyzed. Univariate linear regression models were established to evaluate potential associations between sides regarding LTFHD and FHD as well as a correlation of these parameters with each other. Results Statistically significant side-differences were found for the LTFHD (p = 0.02) and FHD (p = 0.03) with a mean absolute side-difference of 1.6 ± 1.4mm (range 0.1–5.5mm) and 0.4mm ± 0.6mm (range 0–3mm), respectively. The ratio between the LTFHD and FHD was consistent with an average value of 1.16 ± 0.08 and reliable between sides with a correlation coefficient (r) of 0.72 (p Conclusions The LTFHD is a reliable reference parameter for preoperative templating and intraoperative validation during THA with a high correlation between sides (r = 0.93, p

Introduction: The periacetabular osteotomy of Ganz is one of the most demanding procedures in orthopaedic surgery and requires a profound three-dimensional understanding of the human anatomy. The use of augmented reality offers new possibilities for computer-assisted interventions. The aim of our study was to investigate if the navigation of the periacetabular osteotomy of Ganz by the Microsoft HoloLens is feasible in a pilot cadaveric study.

In this work, we developed and validated a computer method capable of robustly detecting drill breakthrough events and show the potential of deep learning-based acoustic sensing for surgical error prevention. Bone drilling is an essential part of orthopedic surgery and has a high risk of injuring vital structures when over-drilling into adjacent soft tissue. We acquired a dataset consisting of structure-borne audio recordings of drill breakthrough sequences with custom piezo contact microphones in an experimental setup using six human cadaveric hip specimens. In the following step, we developed a deep learning-based method for the automated detection of drill breakthrough events in a fast and accurate fashion. We evaluated the proposed network regarding breakthrough detection sensitivity and latency. The best performing variant yields a sensitivity of \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$93.64 \pm 2.42$$\end{document}93.64±2.42% for drill breakthrough detection in a total execution time of 139.29\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\hbox { ms}}$$\end{document}ms. The validation and performance evaluation of our solution demonstrates promising results for surgical error prevention by automated acoustic-based drill breakthrough detection in a realistic experiment while being multiple times faster than a surgeon’s reaction time. Furthermore, our proposed method represents an important step for the translation of acoustic-based breakthrough detection towards surgical use.

Purpose To assess the mechanical properties, tendon resistance to suture cutout, and knot size of a broad variety of high-strength sutures and tapes available for arthroscopic rotator cuff repair. Methods Nine different types of high-strength sutures and tapes for arthroscopic rotator cuff repair were studied: 6 were tapes (FiberTape, Hi-Fi Tape, Permatape, SutureTape, UltraTape, and XBraid TT), and 3 were sutures (Dynacord, FiberWire, and Ultrabraid). First, mechanical tensile testing of suture loops (n = 6) was performed. Second, the suture material was passed through an intact human cadaveric rotator cuff tendon (supraspinatus or infraspinatus), and cyclic as well as load-to-failure testing was performed, 8 times for each suture or tape. Statistical analysis of groups (tapes vs sutures) and between each suture and each tape was performed. Results Material testing revealed significant differences with superior mechanical properties of tapes compared with sutures regarding load for 3 mm of displacement (201 N vs 84 N, P < .0001), displacement at 200 N (3.6 mm vs 6.6 mm, P

The mechanical conflict in symptomatic femoroacetabular impingement can lead to early osteoarthritis. However, radiographic impingement morphology is often seen in asymptomatic individuals. Long-term observation regarding the risk of developing osteoarthritis in these individuals is lacking. Our study addressed the following questions: Does femoroacetabular impingement morphology increase the risk for development of osteoarthritis after at least 25 years? If yes, which radiographic parameter is the most predictive? Does the level of activity influence the risk for development of osteoarthritis? Are PROM influenced by the grade of osteoarthritis in this population? We investigated 51 (32 male, 19 female) patients for whom AP pelvis and Dunn view radiographs were available with a minimum follow-up of 25 years. Alpha angle in AP pelvis and Dunn view radiographs, femoral torsion in Dunn view, lateral center edge angle, cross-over sign, posterior wall sign and prominence of ischial spine sign in AP pelvis radiographs were determined. On the follow-up radiographs, osteoarthritis was graded. Tegner Score for the time of the index radiograph was evaluated. Harris Hip Score and Western Ontario and McMaster Universities Osteoarthritis Index were assessed at latest follow-up. The mean follow-up was 43 years (range 25–58). Cam impingement morphology showed to increase the risk for development of osteoarthritis: Alpha angles of ≥ 55° on AP pelvis and Dunn view radiographs were associated risk factors and showed an OR of 1.05 (p = 0.002) and 1.10 (p = 0.001), respectively. Abnormal femoral torsion and acetabular retroversion were not risk factors for osteoarthritis. Tegner Score at index presentation, HHS and WOMAC Score did not correlate with the grade of osteoarthritis. This study showed that cam impingement morphology in young patients raises the risk for development of hip osteoarthritis by 5–10% in a long-term follow-up with a minimum of 25 years, thus its contribution was small.

The objective of this study was to assess limb and component alignment after total knee arthroplasty (TKA) on long leg X-rays and to compare the use of iAssist, an accelerometric based computer-assisted device (CAD), with conventional jigs.We prospectively recruited 56 consecutive patients undergoing primary unilateral TKA by a single surgeon into this study. In the first 28 patients iAssist navigation system was utilized and in the following 28 conventional jigs were used. The groups were comparable with regard to age, sex distribution, body mass index and preoperative hip-knee-ankle (HKA) angle. Our aim was to restore neutral coronal alignment and a five degree tibial slope.The mean postoperative mechanical axis was 179.4° in the CAD group and 180.1° in the conventional group (P = 0.187). There were five TKAs deviating more than three degrees from neutral (18.5%) in the conventional group and none in the CAD group (P = 0.051). The mean femoral mechanical-condyles-angle was significantly closer (P 0.001) to our target of 90° in the conventional group but contained more outliers (P = 0.67). The sagittal tibial slope was closer (P = 0.047) to our target of 85° in CAD-navigated TKAs with fewer outliers (P 0.0001). The Oxford Knee Score showed comparable (P = 0.271) and good clinical outcome in both groups. The mean operation time was significantly longer in the CAD group (P 0.001).This study shows that the use of iAssist accelerometric CAD facilitates comparable good leg alignment after TKA in the frontal plane and more accurate tibial slope with fewer outliers in the sagittal plane compared with a conventional technique. Our operation time was longer with CAD.

The effect of a distal femur varization osteotomy on patellofemoral biomechanics in genu valgum is unknown. The purpose of this study was to quantify the influence of frontal leg axis correction on the Q-angle with a novel three-dimensional (3-D) measurement method. 3-D surface models of ten lower extremities were generated using patient computed tomography (CT) data. The preoperative 3-D Q-angle was measured using a novel defined and validated 3-D measurement method. Biplanar supracondylar osteotomies were simulated with different degrees of varus correction (from 1° to 15°) in one-degree steps beginning from the preoperative valgus deformity, resulting in a total of 150 simulations. Additionally, mechanical leg axis and 3-D Q-angle measurements were performed on 3-D surface models of the postoperative CT scans of the same individuals. Further, pre- and postoperative TT–TG distance was measured. Mean preoperative Q-angle was 15.8 ± 3.9° (range 10°–21.4°) with a mean preoperative mechanical leg axis of 6.5° ± 2.4 valgus (range 3.8°–11.6° valgus). The Q-angle changed linearly 0.9 ± 0° per 1° of varization. No difference was detected between simulated 3-D Q-angles and effectively corrected postoperative values (n.s.). TT–TG distance changed irregularly and minimally, and with no correlation to the degree of varization. Distal femur varization osteotomy has a linear effect on the Q-angle with a change of 1° per 1° of varization. The difference in TT–TG distance was mainly due to an unintentional rotational component implemented during surgery.

Nerve root compression causing symptomatic radiculopathy can occur within the intervertebral foramen. Sagittal magnetic resonance imaging (MRI) sequences are reliable in detection of nerve root contact to intraforaminal disc material, but a clinically relevant classification of degree of contact is lacking.This study aimed to investigate a potential relation of amount of contact between intraforaminal disc material and nerve root to clinical findings and response after periradicular corticosteroid infiltration.A post hoc analysis of a prospective cohort was carried out.Patients who underwent computed tomography (CT)-guided periradicular corticosteroid infiltration (L1-L5) at our institution (January 2014 to May 2016) were included.The medical records and radiographic imaging were reviewed.T2-weighted MRI of the lumbar spine of patients with single-level symptomatic radiculopathy with (responders, n=28) or without (non-responders, n=14) pain relief after periradicular infiltration with corticosteroids were measured and compared by two independent readers to determine the amount of intraforaminal nerve root contact with the intervertebral disc ("melting" of the T2-hypointense signal). Pain relief was defined with a pain level decrease of50% on a visual analogue scale and lack of pain relief with a pain level decrease of25%, respectively. The amount of T2-hypointensity melting of disc and nerve root was categorized to 0%, 1%-25%, and over 25%.Reader one identified 0% T2-melting in none of the responders, 1%-25% melting in 13 patients (46.4%), 26%-50% in 15 of the 28 patients (53.6%) with pain relief after periradicular corticosteroid infiltration (responders), with a mean amount of T2-melting of 5.9±2.1 mm, whereas the non-responder group had 0% T2-melting in 2 patients (14.3%), 1%-25% T2-melting in 11 patients (78.6%), and 26%-50% in 1 patient (7.1%), with a mean amount of T2-melting of 2.6±1.9 mm (p.05). Reader two identified 0% T2-melting in none, 1%-25% T2-melting in 15 (53.6%) patients, and 26%-50% in 13 of the 28 responders (46.4%), with mean amount of 6.3±1.9 mm. In the non-responder group 0% T2-melting was seen in 3 patients (21.4%), 1%-25% T2-melting in 10 patients (71.4%), and 26%-50% in 1 patient (7.1%), with a mean amount of T2-melting of 2.7±1.9 mm (p.05). None of the MRI showed T2-melting in over 50% of the circumference of the intraforaminal nerve root. A T2-melting of25% had a high specificity of 93% but a sensitivity of 50%, thus a positive likelihood ratio of 7.5, to identify those with a pain relief of more than 50% after infiltration.The amount of T2-melting of disc material and nerve root on sagittal MRI (25%) predicts the amount of pain relief by periradicular infiltration in patients with intraforaminal nerve root irritation.

Despite advances in intraoperative surgical imaging, reliable discrimination of critical tissue during surgery remains challenging. As a result, decisions with potentially life-changing consequences for patients are still based on the surgeon's subjective visual assessment. Hyperspectral imaging (HSI) provides a promising solution for objective intraoperative tissue characterisation, with the advantages of being non-contact, non-ionising and non-invasive. However, while its potential to aid surgical decision-making has been investigated for a range of applications, to date no real-time intraoperative HSI (iHSI) system has been presented that follows critical design considerations to ensure a satisfactory integration into the surgical workflow. By establishing functional and technical requirements of an intraoperative system for surgery, we present an iHSI system design that allows for real-time wide-field HSI and responsive surgical guidance in a highly constrained operating theatre. Two systems exploiting state-of-the-art industrial HSI cameras, respectively using linescan and snapshot imaging technology, were designed and investigated by performing assessments against established design criteria and ex vivo tissue experiments. Finally, we report the use of our real-time iHSI system in a clinical feasibility case study as part of a spinal fusion surgery. Our results demonstrate seamless integration into existing surgical workflows., Journal of Physics D: Applied Physics, 54 (29), ISSN:0022-3727, ISSN:1361-6463

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Background The sacroiliac joint (SIJ) is a frequently underestimated cause of lower back (LBP). A simple clinical test of sufficient validity would be desirable. The aim of this study was to evaluate the diagnostic value of a new PSIS distraction test for the clinical detection of SIJ arthropathy and to compare it to several commonly used clinical tests. Methods Consecutive patients, where a SIJ pathology had been confirmed by an SIJ infiltration were enrolled (case group, 61 SIJs in 46 patients). Before infiltration, patients were tested for pain with PSIS distraction by a punctual force on the PSIS in medial-to-lateral direction (PSIS distraction test), pain with pelvic compression, pelvic distraction, Gaenslen test, Thigh Thrust, and Faber (or Patrick’s) test. In addition, these clinical tests were applied to both SIJs of a population of individuals without history of LBP (control group, 64 SIJs in 32 patients). Results Within the investigated cohort, the PSIS distraction test showed a sensitivity of 100% and a specificity of 89% for SIJ pathology. The accuracy of the test was 94%, the positive predictive value (PPV) was 90% and the negative predictive value (NPV) was 100%. Pelvic compression, pelvic distraction, Gaenslen test, Thigh Thrust, and Faber test were associated with a good specificity (> 90%) but a poor sensitivity (< 35%). Conclusions Within our population of patients with confirmed SIJ arthropathy the PSIS distraction test was found to be of high sensitivity, specificity and accuracy. In contrast, common clinical tests showed a poor sensitivity. The PSIS distraction test seems to be an easy-to-perform and clinically valuable test for SIJ arthropathy.