The opposable thumb is one of the defining characteristics of human anatomy and is involved in most activities of daily life. Lack of optimal thumb motion results in pain, weakness, and decrease in quality of life. First carpometacarpal (CMC1) osteoarthritis (OA) is one of the most common sites of OA. Current clinical diagnosis and monitoring of CMC1 OA disease are primarily aided by X-ray radiography; however, many studies have reported discrepancies between radiographic evidence of CMC1 OA and patient-related outcomes of pain and disability. Radiographs lack soft-tissue contrast and are insufficient for the detection of early characteristics of OA such as synovitis, which play a key role in CMC OA disease progression. Magnetic resonance imaging (MRI) and two-dimensional ultrasound (2D-US) are alternative options that are excellent for imaging soft tissue pathology. However, MRI has high operating costs and long wait-times, while 2D-US is highly operator dependent and provides 2D images of 3D
Tibial plateau fracture reduction involves restoration of alignment and articular congruity. Restorations of sagittal alignment (tibial slope) of medial and lateral condyles of the tibial plateau are independent of each other in the fracture setting. Limited independent assessment of medial and lateral tibial plateau sagittal alignment has been performed to date. Our objective was to characterize medial and lateral tibial slopes using fluoroscopy and to correlate X-ray and CT findings. Phase One: Eight cadaveric knees were mounted in extension. C-arm fluoroscopy was used to acquire an AP image and the C-arm was adjusted in the sagittal plane from 15° of cephalad tilt to 15 ° of caudad tilt with images captured at 0.5° increments. The “perfect AP” angle, defined as the angle that most accurately profiled the articular surface, was determined for medial and lateral condyles of each tibia by five surgeons. Given that it was agreed across surgeons that more than one angle provided an adequate profile of each compartment, a range of AP angles corresponding to adequate images was recorded. Phase Two: Perfect AP angles from Phase One were projected onto sagittal CT images in Horos software in the mid-medial compartment and mid-lateral compartment to determine the precise tangent subchondral
While reverse shoulder arthroplasty (RSA) is a reliable treatment option for patients with rotator cuff deficiency, loss of glenoid baseplate fixation often occurs due to screw loosening. We questioned whether an analysis of the trabecular bone density distribution in the scapula would indicate more optimal sites for screw placement. As such, the purpose of this study was to determine the anatomic distribution of trabecular bone density in regions of the scapula available for screw placement in RSA. Seven cadaveric shoulders were computed tomography (CT) scanned, and then voxels of the scapulae were isolated from the CT volume (Mimics 15.0 Materialise, Leuven, Belgium). Analyses were conducted in a common, 3D coordinate system. Volumetric regions of interest (ROI) within the scapula were identified based on potential baseplate screw sites. ROIs included areas at the base of the coracoid process lateral and inferior to the suprascapular notch, in the posterior and anterior lateral spine and in the anterosuperior and posteroinferior lateral border. Hounsfield Units (HU) were extracted from voxels corresponding to trabecular bone within each ROI. Overall bone density was summarised as the frequency of HU values above 80% of the ROI's maximum density value. Paired, two-tailed t-tests assuming unequal variance were used for pairwise comparisons (P≤0.05). Intra-region analyses compared two ROIs within the same broad
INTRODUCTION. Most total knees today are CR or PS, with lateral and medial condyles similar in shape. There is excellent durability, but a shortfall in functional outcomes compared with normals, evidenced by abnormal contact points and gait kinematics, and paradoxical sliding. However unicondylar, medial pivot, or bicruciate retaining, are preferred by patients, ascribed to AP stability or retention of
Fluoroscopic guidance is common in interventional pain procedures. In spine surgery, injections are used for differential diagnosis and determination of indication for surgical treatment as well. Fluoroscopy ensures correct needle placement and accurate delivery of the drug. Also, exact documentation of the intervention performed is possible. However, besides the patient, interventional pain physicians, surgeons and other medical staff are chronically exposed to low dose scatter radiation. The long-term adverse consequences of low dose radiation exposure to the medical staff are still unclear. Especially in university hospital settings, where education of trainees is performed, fluoroscopy time and total radiation exposure are significantly higher than in private practice settings. It remains a challenge for university hospitals to reduce the fluoroscopic time while maintaining the quality of education. Multiple approaches have been made to reduce radiation exposure in fluoroscopy, including the wide spread use of pulsed fluoroscopy, or rarely used techniques like laser guided needle placement systems. The Zero-Dose-C-Arm-Navigation (ZDCAN) allows an optimal positioning of the c-arm without exposure to radiation. For training purposes, relevant
Aim. To create a more “normal” anatomy for the repaired joint structure, which can be provided that by the following factors: (1) the available implant component require a normalized anatomical support structure, (2) the available repair components are designed and/or tested to only recreate and/or replicate more normalized
This paper describes how advances in three-dimensional printing may benefit the military trauma patient, both deployed on operations and in the firm base. Use of rapid prototype manufacturing to produce a 3D representation of complex fractures that can be held and rotated will aid surgical planning within multidisciplinary teams. Patient-clinician interaction can also be aided using these graspable models. The education of military surgeons could improve with the subsequent accurate, inexpensive models for anatomy and surgical technique instruction. The developing sphere of additive manufacturing (3D printing functional end-use components) lends itself to further advantages for the military orthopaedic surgeon. Military trauma patients could benefit from advances in direct metal laser sintering which enable the manufacture of complex surfaces and porous structures on bio-metallic implants not possible using conventional manufacturing. “Bio-printing” of tissues mimicking
Introduction. Acetabular bone defects are still challenging to quantify. Numerous classification schemes have been proposed to categorize the diverse kinds of defects. However, these classification schemes are mainly descriptive and hence it remains difficult to apply them in pre-clinical testing, implant development and pre-operative planning. By reconstructing the native situation of a defect pelvis using a Statistical Shape Model (SSM), a more quantitative analysis of the bone defects could be performed. The aim of this study is to develop such a SSM and to validate its accuracy using relevant clinical scenarios and parameters. Methods. An SSM was built on the basis of segmented 66 CT dataset of the pelvis showing no orthopedic pathology. By adjusting the SSM's so called modes of shape variation it is possible to synthetize new 3D pelvis shapes. By fitting the SSM to intact normal parts of an
Over the past decades, computer-aided navigation system has experienced tremendous development for minimising the risks and improving the precision of the surgery. Nowadays, some commercially-available and self-developed surgical navigation systems have already been tested and proved successfully for clinical applications. However, all of these systems use computer screen to render the navigation information such as the real-time position and orientation of the surgical instrument, virtual path of preoperative surgical planning, so that the surgeons have to switch between the actual operation site and computer screen which is inconvenient and impact the continuity of surgery. In recent years, Augmented Reality (AR)- based surgical navigation is a promising technology for clinical applications. In the AR system, virtual and actual reality are mixed, offering real-time, high-quality visualisation of an extensive variety of information to the users. Therefore, in this study, a pilot study of a surgical navigation system for orthopaedics based on optical see-through augmented reality (AR-SNS) is presented, which encompasses the preoperative surgical planning, calibration, registration, and intra-operative tracking. With the aid of AR-SNS, the surgeon wearing the optical see-through head-mounted display can obtain a fused image that the 3D virtual critical
For any image guided surgery, independently of the technique which is used (navigation, templates, robotics), it is necessary to get a 3D bone surface model from CT or MR images. Such model is used for planning, registration and visualization. We report that graphical representation of patient bony structure and the surgical tools, inter-connectively with the tracking device and patient-to-image registration, are crucial components in such system. For Total Shoulder Arthroplasty (TSA), there are many challenges. The most of cases that we are working with are pathological cases such as rheumatoid arthritis, osteoarthritis disease. The CT images of these cases often show a fusion area between the glenoid cavity and the humeral head. They also show severe deformations of the humeral head surface that result in a loss of contours. These fusion area and image quality problems are also amplified by well-known CT-scan artefacts like beam-hardening or partial volume effects. The state of the art shows that several segmentation techniques, applied to CT-Scans of the shoulder, have already been disclosed. Unfortunately, their performances, when used on pathological data, are quite poor. In severe cases, bone-on-bone arthritis may lead to erosion-wearing away of the bone. Shoulder replacement surgery, also called shoulder arthroplasty, is a successful, pain-relieving option for many people. During the procedure, the humeral head and the glenoid bone are replaced with metal and plastic components to alleviate pain and improve function. This surgical procedure is very difficult and limited to expert centres. The two main problems are the minimal surgical incision and limited access to the operated structures. The success of such procedure is related to optimal prosthesis positioning. For TSA, separating the humeral head in the 3D scanner images would allow enhancing the vision field for the surgeon on the glenoid surface. So far, none of the existing systems or software packages makes it possible to obtain such 3D surface model automatically from CT images and this is probably one of the reasons for very limited success of Computer Assisted Orthopaedic Surgery (CAOS) applications for shoulder surgery. This kind of application often has been limited due to CT-image segmentation for severe pathologic cases and patient to image registration. The aim of this paper is to present a new image guided planning software based on CT scan of the patient and using bony structure recognition, morphological and anatomical analysis for the operated region. Volumetric preoperative CT datasets have been used to derive a surface model shape of the shoulder. The proposed planning software could be used with a conventional localisation system, which locates in 3D and in real time position and orientation for surgical tools using passive markers associated to rigid bodies that will be fixed on the patient bone and on the surgical instruments. 20 series of patients aged from 42 years to 91 years (mean age of 71 years) were analysed. The first step of this planning software is fully automatic segmentation method based on 3D shape recognition algorithms applied to each object detected in the volume. The second step is a specific processing that only treats the region between the humerus and the glenoid surface in order to separate possible contact areas. The third step is a full morphological analysis of
Pelvic incidence is as a key factor for sagittal balance regulation that describes the anatomical configuration of the pelvis. The sagittal alignment of the pelvis is usually evaluated in two-dimensional (2D) sagittal radiographs in standing position by pelvic parameters of sacral slope, pelvic tilt and pelvic incidence (PI). However, the angle of PI remains constant for an arbitrary subject position and orientation, and can be therefore compared among subjects in standing, sitting or supine position. Such properties also enable the measurement of PI in three-dimensional (3D) images, commonly acquired in supine position. The purpose of this study is to analyse the sagittal alignment of the pelvis in terms of PI in 3D computed tomography (CT) images. A computerised method based on image processing techniques was developed to determine the anatomical references, required to measure PI, i.e. the centre of the left femoral head, the centre of the right femoral, the centre of the sacral endplate, and the inclination of the sacral endplate. First, three initialisation points were manually selected in 3D at the approximate location of the left femoral head, right femoral head and L5 vertebral body. The computerised method then determined the exact centres of the femoral heads in 3D from the spheres that best fit to the 3D edges of the femoral heads. The exact centre of the sacral endplate in 3D was determined by locating the sacral endplate below the L5 vertebral body and finding the midpoint of the lines between the anterior and posterior edge, and between the left and right edge of the endplate. The exact inclination of the sacral endplate in 3D was determined from the plane that best fit to the endplate. Multiplanar 3D image reformation was applied to obtain the superposition of the femoral heads in the sagittal view, so that the hip axis was observed as a straight not inclined line and all
Analysis of orthopaedic malpractice claims has shown that highest impact allegations (highest payment dollars per claim) were those that were related to failure to protect
The aim was to identify the acetabular center, fix the acetabular implant, and reconstruct the hip rotation center using the residual Harris fossa and acetabular notch as anatomical markers during revision hip arthroplasty. Osteolysis is commonly found in the acetabulum during hip arthroplasty revision. It causes extensive defects and malformation of the
Introduction. Prosthetic replacement remains the treatment of choice for displaced femoral neck fractures in the elderly population, with recent literature demonstrating significant functional benefits of total hip arthroplasty (THA) over hemiarthroplasty. Yet the fracture population also has historically high rates of early postoperative instability when treated with THA. The direct anterior approach (DAA) may offer the potential to decrease the risk of postoperative instability in this high-risk population by maintaining posterior
Background. External fixation for a fracture-dislocation to a joint like the elbow, while maintaining joint mobility is currently done after identifying the center of rotation under X-ray guidance, when applying either a mono-lateral or a circular fixator. Current treatment. using the galaxy fixation system by Orthofix, the surgeon needs to correctly identify the center of rotation of the elbow under X-ray guidance on lateral views. If the center of rotation of the fixator is not aligned with that of the elbow joint, the assembly will not work, i.e. the elbow will be disrupted on trying to achieve flexion or extension movements. Figures (A, B, C and D) summarize the critical steps in identifying the centre of rotation (Courtesy of Orthofix Orthopedics International). New design. This new idea aims to propagate the principle of sliding external fixation applied on the extensor side of a joint, with the limbs of the fixator being able to slide in and out during joint extension and flexion respectively, without hindering the joint movement. Taking the ulno-humeral joint as an example, it is enough to apply the sliding external fixator in line with the subcutaneous border of the ulna, and the pins in the sagital plane, without the need to use x-ray guidance to identify the center of rotation, which simplifies the procedure, and makes it less technically demanding. The sliding external fixator over the elbow involves two bars which accommodate half pins fixation with headless grip screws to hold the pins, identical to the Rancho cubes technique by Smith & Nephew, these slide snugly into sleeves, those sleeves linked together through a hinge behind the elbow, and the bars are spring loaded to the hinge through the inside of the sleeves, which means they will slid into the sleeves in extension and out in flexion. Length of the sleeve should prevent the bars from dislodgement, and the cross section of both the bars and the sleeves have to correspond to each other for the sleeves to accommodate the bars within them and to prevent rotational instability within the construct itself. Summary. Applying an external fixator on the extensor surface is an idea could lead to major changes in external fixation product design, the ulno-humeral joint is taken as an example, and other joints could also be addressed taking in consideration joint size and
There has been great enthusiasm over the last few years for the mini-anterior, or, the Direct Anterior (DA) approach. As the title of this session suggests there is a perception that there are features of this approach that result in an unusually rapid recovery with “early” return to a high level of function. There have also been claims of improved implant placement and limb length restoration. This is presumably a result of the use of intra-operative imaging. When originally described, it was stated that the DA permitted THA “without cutting any tendons.” The implication was that the alleged unique recovery was due to this particular feature. Over the last decade I have used a trans-gluteal, direct posterior (DP) approach. Incision into the ITB is not required and quadratus femoris is preserved. The conjoined tendon, occasionally the piriformis, and rarely the obturator externus are released. Over the last 5 years I have used intra-operative digital radiography to guide the procedure. A review of published DA results indicates at least clinical equivalence with the DP. Recent publications describing DA technique acknowledge that it is required, in most cases, to release conjoined tendon, and possibly piriformis. Personal communication with DA practitioners suggests even more “posterior release” is required. I will illustrate that the DP is a very close anatomic equivalent of the DA. It is therefore the handling of critical
The use of a tourniquet when performing total knee arthroplasty (TKA) is subject to different methodologies. Some surgeons see no need to use a tourniquet, others use the tourniquet only during cementation, some utilise the tourniquet from prior to incision to after cementation, while others maintain throughout and release after closure. At our center, use of the tourniquet is part of the TKA routine: position the patient, administer antibiotics, inflate the tourniquet, note pressure and time, complete preparation and draping, set time-out, and cut. We release the tourniquet after cementation of components, prior to assessment of patellofemoral tracking and closure. Advantages of using a tourniquet are enhanced TKA durability, less blood during cementation, and reduced intra-operative blood loss and need for transfusion. Adequately preparing the bone surfaces and cleaning away blood and fat are essential to good cement technique, providing better interdigitation and penetration and resulting in fewer radiolucencies and longer survivorship. Lateral retinacular release, performed to alleviate patellar maltracking, is not a benign procedure and is associated with increased patellar complications including loosening, fracture, and avascular necrosis. Several articles, including one from our center, have studied the effect of tourniquet deflation and patellar tracking, observing 31% to 86% reduction in maltracking and indication for lateral release when assessing after deflation. A prospective study of 28 patients undergoing same day bilateral TKA using a tourniquet inflated prior to incision and released after cementation on one side and either no tourniquet or tourniquet only during cementation of the contralateral side found slightly lowered quadriceps strength in the tourniquet group that persisted for up to 3 months. However, another recent prospective study of 120 patients assessing wound closure in 90 degrees flexion versus full extension, with the combination of an inflated versus deflated tourniquet, found that closure of the knee in flexion after tourniquet deflation significantly decreased post-operative pain and promoted early recovery of ROM. Safe use of the tourniquet is essential to avoid neurologic injury, and includes pneumatic, wider, contoured cuffs, moderate maximum applied pressure, and monitoring during release for emboli and metabolite return. Operative efficiency minimises overall operative and tourniquet time, thereby reducing risk of complications. Several meta-analysis reviews have compared TKA performed with versus without use of a tourniquet. All found using a tourniquet resulted in a significant decrease in operative time and intra-operative blood loss, but a trend for increase in deep vein thrombosis and wound complications. Other meta-analysis articles have studied time of tourniquet release comparing early versus late. These studies unanimously found late release to be associated with substantial increase in post-operative complications. Some studies found early release before wound closure to be associated with increased total blood loss and greater drop in hemoglobin while the other studies reported no differences in these measures. Our practice is to deflate the tourniquet prior to wound closure and to achieve hemostatis. The use of a tourniquet to perform TKA facilitates efficient operative technique, improves visualization of
INTRODUCTION. Mechanical tissue properties of some ligaments and tendons have been described in the literature. However, to our knowledge no data exists describing the tensile properties of the Iliopsoas tendon. The iliopsoas complex is in very close proximity to the hip joint running through the psoas notch from the inner side of the pelvis to the lesser trochanter on the posterior aspect of the proximal femur. The tendon muscle complex wraps around the anterior aspect of the femoral head. Hip joint intervention such as total hip arthroplasty (THA) can interfere with iliopsoas function and contact mechanics, and thereby play a major role in the clinically known condition of anterior hip pain. For computer simulations such as finite element analysis (FEA) precise knowledge of soft-tissue mechanical properties is crucial for accurate models and therefore, the goal of this study was to describe the iliopsoas tensile properties using uniaxial testing equipment. METHODS. Ten iliopsoas tendons were harvested from five specimens (2 male, 3 female; 82.4 yrs ±7.4 yrs) and then carefully cleaned from any fat and muscle tissue. Two freeze clamps were fixed to each end of the tendon sample. The clamps were submerged in liquid nitrogen for 30 seconds to prevent tendon slip and attached to the test frame and load cell via carabiners allowing the tendon to rotate around its long axis. Width, thickness and initial gauge length of each tendon were measured before testing. The test protocol included 10 cycles of preconditioning between 6 N and 60 N at 0.4 mm/s, followed by continuous distraction at 0.4 mm/s until failure. For each tendon the linear stiffness was determined by fitting a straight line to the liner region on the force-displacement curve (Fig. 1). RESULTS. The average linear stiffness of the ten iliopsoas tendons was measured to be 339 N/mm ±81 N/mm and the average failure load resulted in 2154 N ±418 N (Fig. 2). Average width and thickness were determined to be 13.9 mm ±3.2 mm and 3.8 mm ±0.5 mm respectively. The initial gauge length of the ten tendons revealed an average of 56.5 mm ±10.5 mm. CONCLUSION. An average stiffness of 339 N/mm and average failure load of 2154 N was found in our experiments. A trend of increased stiffness and reduced failure load with higher age could be observed. Soft-tissue mechanical properties are dependent on tissue geometry such as cross-sectional area and length and therefore can be variable in comparison with other
Functional Ultrasound Elastography (FUSE) of Tendo Achilles is an ultrasound technique utilising controlled, measurable movement of the foot to non-invasively evaluate TA elastic and load-deformation properties. The study purpose is to assess Achilles tendons, paratenon and bursa mechanical properties in healthy volunteers and establish a clinical outcome tool for TA treatment. We studied 40 Achilles tendons in healthy volunteers using our novel Elastography method, which we developed in the University of Oxford. US scan device (Z.one, Zonare Medical System Inc., USA, 8.5 MHz) with and without the Oxford isometric dynamic foot and ankle mover were used. Tendon insertion, midportion and musculotendinous junction were examined during lateral movement and axial compression/decompression modes. B mode and elasticity images were derived from the raw ultrasound radio frequency data. The
Limited postoperative range-of-motion (ROM) can lead to patient dissatisfaction and dislocation in total hip arthroplasties (THAs). To avoid this, femur first approaches have been developed which optimise particular aspects of ROM by using a virtual analysis of ROM. This study analysis whether it is possible to accurately assess ROM based on an intra-operative acquisition of
