Intra-operative Tip-Apex Distance (TAD) estimation optimises dynamic hip screw (DHS) placement during hip fracture fixation, reducing risk of cut-out. Thread-width of a standard DHS screw measures approximately 12.5 millimetres. We assessed the effect of introducing screw thread-width as an intra-operative distance reference to surgeons. The null hypothesis was that there were no differences between hip fracture fixation before and after this intervention. Primary outcome measure was TAD. Secondary outcome measures included position of the screw in the femoral head, quality of reduction, cut-out and surgeon accuracy of estimating TAD. 150 intra-operative DHS radiographs were assessed before and after introducing screw thread-width distance reference to surgeons. Mean TAD reduced from 19.37mm in the control group to 16.49mm in the prospective group (p=<0.001). The number of DHS with a TAD > 25mm reduced from 14% to 6%.
Open-wedge high tibial osteotomy (OWHTO) is an operation involving proper load re-distribution in the treatment for medial uni-compartmental arthritis of the knee joint. Therefore, stable fixation is mandatory for safe healing of this additive type of osteotomy to minimize the risk of non-union and loss of correction. For stability, screws provide optimal support and anchorage of the fixator in the condylar area without risking penetration of either the articulating surface. The purpose of the study was to evaluate the screw insertion angle and orientation with an anatomical plate that is post-contoured to the surface geometry of the proximal tibia after OWHTO. From March 2012 to June 2014, 31 uni-planar and 38 bi-planar osteotomies were evaluated. Postoperative computed tomography data obtained after open wedge high tibial osteotomy using a locking plate were used for reconstruction of the 3 dimensional model with Mimics v.16.0 of the proximal tibia and locking plate. Measurement data were compared between 2 groups (gap lesser than or equal to 10 mm (Group 1) and gap greater than 10 mm(Group 2)). These data were also compared between the uniplanar (Group 3) and bi-planar (Group 4) osteotomy groups.Background
Methods
Soft tissue balancing in total knee replacement may well be the determining factor in raising the fair patient satisfaction. The development of intelligent implants allows quantification of reactive loads to applied pressures. This can be tested in dynamic mode such as heel push test at surgery, or in static mode such as when testing for varus/valgus (VV) laxity of the collateral ligaments of the knee. We postulate that a well-balanced knee will have comparable if not equal load distribution across compartments in dynamic loading. When tested for laxity, we anticipate an equal or comparable response to VV applied loads under physiologic load range of 10–50N. This study sought to analyze the relationship between the kinematic (joint motion) and kinetic (force) effects to VV testing in the 0–15 degrees range of flexion. One goal was to demonstrate that testing the knee in locked extension (Screw Home effect) is unreliable and should be abandoned in favor of the more reliable VV testing at 10–15 degrees of flexion. This is a preliminary cadaveric study utilizing data from two hemibodies. The pelvis was fixed in a custom test rig with open or closed chain lower leg testing capability along a sliding rail with foot VV translational. Forces were applied at the malleoli with a wireless hand held dynamometer. Kinematic analysis of the hip-knee-ankle (HKA) tibiofemoral angle was derived from a commercial navigation system with mounted infrared trackers. Kinetic analysis was derived from a commercially available sensor imbedded in a tibial trial liner. Balance was optimized by conventional methods with the use of the sensor feedback until loads were roughly symmetrical and VV testing yielded symmetrical rise in opposite compartments. The VV testing was then performed with the knees locked at the femoral side in axial rotation and translational motion in any plane. Sagittal flexion was pre-set at 0, 10, and 15 degrees and progressive load was applied. From the graphs one can observe significant differences between VV testing at 0 degrees (locked Screw Home), 10 degrees, and 15 degrees of flexion. The shaded area corresponds to the common range of VV stress testing loading pressure, typically less than 35N. The HKA deviates from neutrality no sooner than by the middle of the physiologic test zone. By 35N, the magnitude of the effect is also much less than that observed at 10 and 15 degrees (unlocked from Screw Home). From the kinetic analysis one can also note the significant difference in the High-Low spread throughout the testing range of applied pressure. If the surgeon tests in the low range of applied loads, he/she may not observe the kinematic joint opening effect. The kinetic effect seems more reliable as sensed loads are detectable earlier on. It is clear however that testing at 10–15 degrees offers a much better sensitivity to the VV laxity or stiffness as exemplified in the bottom portions of the figure. Therefore testing in locked Screw Home full extension may lead to underestimation of the true coronal laxity of the joint.Results
Reverse shoulder arthroplasty (RSA) is commonly used to treat patients with rotator cuff tear arthropathy. Loosening of the glenoid component remains one of the principal modes of failure and is the main complication leading to revision. For optimal RSA implant osseointegration to occur, the micromotion between the baseplate and the bone must not exceed a threshold of 150 µm. Excess micromotion contributes to glenoid loosening. This study assessed the effects of various factors on glenoid baseplate micromotion for primary fixation of RSA. A half-fractional factorial experiment design (2k-1) was used to assess four factors: central element type (central peg or screw), central element cortical engagement according to length (13.5 or 23.5 mm), anterior-posterior (A-P) peripheral screw type (nonlocking or locking), and bone surrogate density (10 or 25 pounds per cubic foot [pcf]). This created eight unique conditions, each repeated five times for 40 total runs. Glenoid baseplates were implanted into high- or low-density Sawbones™ rigid polyurethane (PU) foam blocks and cyclically loaded at 60 degrees for 1000 cycles (500 N compressive force range) using a custom designed loading apparatus. Micromotion at the four peripheral
Summary. Optimum position of pedicle screws can be determined preoperatively by CT based planning. We conducted a comparative study in order to analyse manually determined pedicle screw plans and those that were obtained automatically by a computer software and found an agreement in plans between both methods, yet an increase in fastening strengths was observed for automatically obtained plans. Hypothesys. Automatic planning of pedicle
The purpose of this study is to quantify the distribution of bone density in the scapulae of patients undergoing reverse shoulder arthroplasty (RSA) to guide optimal screw placement. To achieve this aim, we compared bone density in regions around the glenoid that are targeted for screw placement, as well as bone density variations medial to lateral within the glenoid. Specimen included twelve scapula in 12 patients with a mean age of 74 years (standard deviation = 9.2 years). Each scapula underwent a computed tomography (CT) scan with a Lightspeed+ XCR 16-Slice CT scanner (General Electric, Milwaukee, USA). Three-dimensional (three-D) surface mesh models and masks of the scapulae containing three-D voxel locations along with the relative Hounsfield Units (HU) were created. Regions of interest (ROI) were selected based on their potential glenoid baseplate
Purpose of study:. Reverse shoulder arthroplasty is effective in the management of symptomatic arthritic shoulders with a non-reconstructable rotator cuff. Optimal orientation and initial fixation of the glenoid component is correlated with improved outcomes. This may be difficult to achieve with distorted glenoid morphology. The authors present a previously undescribed system for accurate, consistent and reliable screw placement for fixation of the glenoid component with the desired version during reverse shoulder arthroplasty. Description of methods:. The pre-operative CT scan images are used to construct a scapula model (Medical Image Processing software, CustomMed Orthopaedics)allowing the surgeon to determine the optimal
Introduction. Total shoulder replacement is a successful treatment for gleno-humeral osteoarthritis. However, components loosening and painful prostheses, related to components wrong positioning, are still a problem for those patients who underwent this kind of surgery. CT-based intraoperative navigation system is a suitable option to improve accuracy and precision of the implants as previously described in literature for others district. Method. Eleven reverse shoulder prostheses were performed at Modena Polyclinic from October 2018 to April 2019 using GPS CT-based intraoperative navigation system (Exactech, Gainsville, Florida). In the preoperative planning, Walch classification was used to assess glenoid type. The choice of inclination of the glenoid component, the screw length, as well as the inclination of the reamer was study and recorded using specific software using the CT scan of shoulder of each patient (Fig.1, Fig.2). Intraoperative and perioperative complications were recorded. Three patients were male, eight were female. Mean age was 72 years old (range 58=84). Three glenoid were type B2, six cases were B1, two case were type C1. Results. In all cases treated by reverse shoulder prostheses we had obtain good functional results at preliminary follow up. Eight degree posterior augment was used in seven case. Planned version was 0° in eight case, an anti-version of 3° was planned in the other three cases. Final reaming was as preoperatively planned in all cases except one. Mean surgical time was 71 minutes (range 51–82). One case of coracoid rupture has been reported. In all cases the system worked in proper manner without failures, no case of infection was reported. Discussion. It is well known as the more accurate placement of the glenoid led to enhanced long-term survivorship of the implant and decrease complication rates in RSTA. Our first experience with GPS navigation system has been satisfied. Good components’ positioning has been reached in all cases, without deviation from the preoperative planning. Pre-operative preparation using software has been always respected except in one case in which we decided to ream 1mm less to avoid excessive bone loss. In 3 case we decide to increase glenoid anti-version to allow a good cage containment in the scapula. No failure of the system has been recorded, with a little increase in the surgical time respect to traditional surgeries performed in our institute. The first case performed reported coracoid fracture, probably due to lack of experience in coracoid tracker positioning. It is very important to set the surgical theatre and the position of the patient in order to make the coracoid tracker visible for the computer.
Introduction. IM (Intra Medullary) nail fixation is the standard treatment for diaphyseal femur fractures and also for certain types of proximal and distal femur fractures. Despite the advances in the tribology for the same, cases of failed IM nail fixation continue to be encountered routinely in clinical practice. Common causes are poor alignment or reduction, insufficient fixation and eventual implant fatigue and failure. This study was devised to study such patients presenting to our practice and develop a predictive model for eventual failure. Materials and Methods. 57 patients who presented with failure of IM nail fixation (± infection) between Jan 2011 – Jun 2020 were included in the study and hospital records and imaging reviewed. Those fixed with any other kinds of metalwork were excluded. Classification for failure of IM nails – Type 1: Failure with loss of contact of lag screw threads in the head due to backing out and then rotational instability, Type 2A: Failure of the nail at the nail and lag screw junction, Type 2B: Failure of the screws at the nail lag screw junction, Type 3: Loosening at the distal locking sites with or without infection. X-rays reviewed and causes/site of failure noted. Results. Total patients - 57. Demography - Average age - 58.9 years, 22 Males and 35 females. Eleven patients were noted to have an infection at the fracture site that needed oral or IV antibiotics.16 patients - at least 1 cerclage wire for fracture reduction and fixation + IM Nail. Subtrochanteric fractures (42/57) were the most common to fail. In those fractures with postero-medial comminution, locking of the lag
In orthopaedic spine surgery pedicle screw systems are used for stabilisation of the spine after injuries or disorders. With an percutaneous operation method surgeons are faced with huge challenges compared to an open surgery, but it's less traumatic and the patient benefits with a faster rehabilitation and less traumatic injuries. The
Pedicle screw fixation is a technically demanding procedure with potential difficulties and reoperation rates are currently on the order of 11%. The most common intraoperative practice for position assessment of pedicle screws is biplanar fluoroscopic imaging that is limited to two- dimensions and is associated to low accuracies. We have previously introduced a full-dimensional position assessment framework based on registering intraoperative X-rays to preoperative volumetric images with sufficient accuracies. However, the framework requires a semi-manual process of pedicle screw segmentation and the intraoperative X-rays have to be taken from defined positions in space in order to avoid pedicle screws' head occlusion. This motivated us to develop advancements to the system to achieve higher levels of automation in the hope of higher clinical feasibility. In this study, we developed an automatic segmentation and X-ray adequacy assessment protocol. An artificial neural network was trained on a dataset that included a number of digitally reconstructed radiographs representing pedicle screw projections from different points of view. This model was able to segment the projection of any pedicle screw given an X-ray as its input with accuracy of 93% of the pixels. Once the pedicle screw was segmented, a number of descriptive geometric features were extracted from the isolated blob. These segmented images were manually labels as ‘adequate’ or ‘not adequate’ depending on the visibility of the screw axis. The extracted features along with their corresponding labels were used to train a decision tree model that could classify each X-ray based on its adequacy with accuracies on the order of 95%. In conclusion, we presented here a robust, fast and automated pedicle screw segmentation process, combined with an accurate and automatic algorithm for classifying views of pedicle screws as adequate or not. These tools represent a useful step towards full automation of our pedicle
Traditional risk factors for post-operative neuropathy include learning curve of surgical approach, DDH, and significant leg lengthening (>1 inch). Despite these risk factors, the most common scenario of a neuropathy is in a routine THA, by an experienced surgeon, for osteoarthritis, with no leg lengthening. Post-operative hematoma can lead to nerve compression, albeit rarely. The usual clinical presentation is of an acute event, with a previously intact nerve, sometime within the first days of surgery. Once diagnosed, immediate surgical decompression should be performed. Sciatic neuropathy is the most common, regardless of surgical approach, but the posterior approach poses the highest risk. Routine gluteus maximus tendon release may help to reduce the risk. When seen in the PACU, our approach is to immediately perform CT imaging to evaluate nerve integrity or to check on acetabular
Acetabular component orientation can directly influence dislocation rates, polyethylene wear, and revision rates. Precise placement has been found to occur in only 38–47% after total hip arthroplasty (THA). The recent introduction of digital radiography (DR) has enabled a paradigm shift in intra-operative imaging technology. Rather than deal with the cumbersome process of chemical image processing we can now acquire a high quality digital image in a matter of seconds. The functionality approaches that of fluoroscopy, or even a C-arm, however, a digital system can operate with lower radiation, higher resolution, and perhaps most importantly a larger field of view. These features make it very suitable for use during surgery. The purpose of this presentation is to illustrate the current intra-operative technique and share the overwhelmingly positive experience gathered over the past five years. Traditional THA employs use of post-operative radiography for “outcome assessment.” This unfortunately does not allow the surgeon to evaluate the relevant parameters and make necessary adjustments without returning to the operating room. Digital imaging, however, permits intra-operative guidance and “outcome control.” It provides an immediate and complete preview of what the post-operative film will show. There is now an opportunity to optimise component orientation, sizing, apposition,
Background. The Robotic Spinal Surgery System (RSSS) is a robot system designed for pedicle screw insertion containing image based navigation system, trajectory planning system and force state recognition system. The special force state recognition system can guarantee the safety during the operation. The RSSS is helpful in pedicle screw insertion surgery and it will be applied in clinic in the near future. In this study, we evaluated the accuracy and safety of RSSS in an animal experiment. Methods. Computer tomography (CT) scan data for two anesthetised experimental sheep was acquired using the C-arm and transferred to RSSS for pre-surgery screw trajectory planning. With the assist of RSSS, we inserted 8 and 4 screws into two sheep respectively. Operation time and blood loss during the surgery were recorded, and CT scan was repeated after surgery. Real
The aim of this retrospective study was to evaluate the failure rate among different fixation devices for undisplaced fracture neck of femur. All 52 patients with Garden I and II hip fractures who underwent surgery in a teaching hospital in London from January 2007 to June 2012 were included. Electronic patient records were accessed to collect the patient data. There were 52% females and the mean age of patients was 70 years. Thirty patients had cannulated screws, 18 – dynamic hip screw (DHS) with de-rotation screw and 4 had DHS alone. Initial results showed that 36% patients had re-operation. 7(77%) had total hip replacement and 1(11%) had metal work removal. The reason for revision was failure of fixation in 8 (88%) and avascular necrosis in 1 (11%). There was significantly higher failure rate in the DHS with derotation screw group (50%) compared to the cannulated screw group (35%) and the DHS alone group (0%). Average time to planned revision was 11.1 months. Traditionally undisplaced intra capsular hip fractures are treated by in-situ fixation using different devices. Biomechanically DHS with de-rotation screw achieves better rotational and axial stability compared to other fixation devices. However, our study showed a higher failure rate in this group. Inability to achieve a perfectly parallel
Background. Composite screws of uncalcined and unsintered hydroxyapatite (HA) particles and poly-l-lactide (PLLA) were developed as completely absorbable bone fixation devices. So far the durability of HA-PLLA composite screws is unclear when used for the fixation of acetabular bone graft in total hip arthroplasty under full-weight conditions. We have used this type of screw for the fixation of acetabular bone graft in cemented or reverse-hybrid total hip arthroplasty since 2003. Hence, we conducted a follow-up study to assess the safety and efficacy of these screws when used for cemented socket fixation. Methods. During 2003–2009, HA-PLLA composite screws were used for fixation of acetabular bone graft in cemented or reverse-hybrid primary THA in 106 patients (114 cases). All the THAs were performed through direct lateral approaches, and postoperative gait exercise with full weight bearing usually started two days after surgery. One patient died of an unrelated disease and seven patients were lost to follow-up within 5 years. Finally, 98 patients (106 cases) were followed up for over 5 years and were reviewed retrospectively (follow-up rate, 93%). Radiographic loosening of the acetabular component was assessed according to the criteria of Hodgkinson et al., and the radiolucent line around the socket was evaluated in all zones, as described by DeLee and Charnley. Results. The patient population comprised 10 men and 88 women with a mean age of 60.3 years (range, 41–81 years) at the time of surgery. The mean follow-up period was 7.6 years (range, 5–11 years). The original diagnosis for primary THA was secondary osteoarthritis in 97 cases and high hip dislocation in nine cases. No patient in this series required revision surgery, and no radiographical loosening occurred during the follow-up period. Grafted bone union was confirmed in all cases, and no apparent osteolysis around the cemented socket or composite screws was detected. Configurations of the HA-PLLA composite screws appeared obscure on radiographs at 5 years after surgery, and only osteosclerotic traces remained in the
The recent introduction of digital radiography has enabled a paradigm shift in intra-operative imaging technology. Rather than deal with the cumbersome process of chemical image processing we can now acquire a high quality digital image in a matter of seconds. The functionality approaches that of fluoroscopy, or even a C-arm, however, a digital system can operate with lower radiation, higher resolution, and perhaps most importantly a larger field of view. These features and the greater ability for post-acquisition, digital image enhancement make it very suitable for use during surgery. The purpose of this presentation is to illustrate the intra-operative technique and share the overwhelmingly positive experience gathered over the past few years. The current paradigm in total hip arthroplasty (THA) employs use of post-operative radiography for “outcome assessment.” This unfortunately does not allow the surgeon to evaluate the relevant parameters and make necessary adjustments without returning to the operating room. The new paradigm, however, permits intra-operative guidance and “outcome control.” We now have an opportunity to add a “trial radiograph” to our practice of performing a trial reduction. This provides an immediate and complete preview of what the post-operative film will show. There is now an opportunity, during the course of any hip arthroplasty, to optimise component orientation, sizing, apposition,
Minimally invasive (MIS) screw fixation for Hangman's fracture can decrease iatrogenic soft-tissue injury compared with conventional open approach, but increase the risk of instrumentation-related complications due to lack of anatomical landmarks. With the advantages, the intra-operative three-dimensional fluoroscopy-based navigation (ITFN) system seems to be an inherent partner for MIS techniques. The purpose of this study was to evaluate the accuracy and feasibility of MIS techniques incorporating with ITFN for treating Hangman's fracture. 20 patients with Hangman's fracture underwent C2-C3 pedicle screw fixation using ITFN. 6 patients used MIS technique, with the other 14 patients using conventional open technique. Preoperative visual analogue score (VAS) was 5.7±1.4 in CAOS-MIS group and 5.5±0.9 in CAOS-open group. Operative time, blood loss and postoperative neurovascular complications were recorded. The accuracy of
In recent years internal fixation of the spine by using posterior approach with minimally invasive and percutaneous technique were increasingly used in trauma. The percutaneous surgery lose information and navigation is supposed to provide better data because the lost information is found again. We hypothesise that a percutaneous minimal invasive dorsal procedure by using 3D intra-operative imaging for vertebral fractures allows short operating times with correct
Objectives. Percutaneous iliosacral screw placement is a standard, stabilization technique for pelvic fractures. The purpose of this study was to assess the effectiveness of a novel biplanar robot navigation aiming system for percutaneous iliosacral screw placement in a human cadaver model. Methods. A novel biplanar robot navigation aiming system was used in 16 intact human cadaveric pelvises for percutaneous iliosacral screw insertion. The number of successful screw placements and mean time for this insertion and intra-operative fluoroscopy per screw-pair were recorded respectively to evaluate the procedure. The accuracy of the aiming process was evaluated by computed tomography. Results. Sixteen intact human cadaveric pelvises were treated with percutaneous bilateral iliosacral S1 screw placement (32 cannulated screws, diameter-7.3mm, Synthes, Switzerland). All screws were placed under fluoroscopy-guided control using the biplanar robot navigation aiming system (TINAV, GD2000, China). There was no failed targeting for screw-pair placements. Computed tomography revealed high accuracy of the insertion process. 32 iliosacral screws were inserted (mean operation time per screw-pair 56 ± 3 minutes, mean fluoroscopy time per screw-pair 11.7 ± 9 seconds). In post-operative CT-scans the
