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At least 937 records · Page 52Linked to original sources
PubMed1989

Kinematics of the ankle/foot complex: plantarflexion and dorsiflexion.

In an in vivo investigation of eight healthy volunteers, three dimensional ankle/foot kinematics were analyzed by roentgen stereophotogrammetry in 10 degrees steps of motion from 30 degrees of plantar flexion to 30 degrees of dorsiflexion of the foot. The study included all of the joints between the tibia and the first metatarsal, as well as the talocalcaneal joint, and was performed under full body load. Although the talocrural joint was found to account for most of the rotation around the transverse axis occurring from 30 degrees of plantar flexion to 30 degrees of dorsiflexion, there was a substantial contribution from the joints of the arch. This was seen particularly in the input arc from 30 degrees of plantar flexion to the neutral position, where the dorsiflexion motion of these joints amounted to 10% to 41% of the total transverse axis rotation.

Adult↗
PubMed1989

Kinematics of the ankle/foot complex--Part 3: Influence of leg rotation.

In an in vivo kinematical investigation, the movements of the ankle/food complex induced by external rotation of the leg from an internally rotated position were analyzed by roentgen stereophotogrammetry. Radiopaque markers were introduced into the tibia, talus, calcaneus, navicular, medial cuneiform, and first metatarsal bones of eight healthy volunteers. Rotations occurring between these bones after 10 degrees increments of leg rotation were calculated in three dimensions. Movement of the leg from an internally rotated position to the neutral was found to induce motion mainly as internal rotation of the talus in relation to the tibia. Further external rotation induced motion mainly in the talonavicular and talocalcaneal joints, whereas a smaller amount of motion was seen in the joint between the navicular and the medial cuneiform.

Ankle Joint↗
PubMed1990

Fibular mobility in chronic lateral instability of the ankle.

Using roentgen stereophotogrammetric analysis we recorded the mobility of the lateral malleolus under maximum passive plantarflexion and dorsiflexion and during the anterior drawer and the adduction tests in 29 patients with chronic lateral instability of the ankle. Medial and anterior displacements were observed during plantarflexion, at the adduction test and at the posterior loading of the tibia. At dorsiflexion we recorded posterior fibular shifts. The simultaneously occurring fibular rotations were small. Chronic lateral instability of the ankle was associated with slightly increased fibular movements during plantarflexion and dorsiflexion, and at the adduction test in some patients with bilateral symptoms, perhaps reflecting a generalized joint laxity.

Adolescent↗
PubMed1995

Measurement of the forefoot with roentgen stereophotogrammetry in hallux valgus surgery.

Eight hallux valgus patients were marked with tantalum markers in conjunction with hallux valgus surgery (seven proximal osteotomies and one chevron osteotomy). Changes on weightbearing before surgery as well as corrective changes after surgery were analyzed with roentgen stereophotogrammetry (RSA) and with standard x-rays. RSA is accurate to 0.6 degrees in rotational changes and 0.3 mm in translation. Weightbearing changes were inconsistent, and minimal with both standard x-rays and RSA. It was possible to analyze the correction at the osteotomy site with RSA. In half the cases, the correction measured by RSA corresponded with that measured with standard x-rays, within measurement error; in the other cases, RSA showed that the correction was of a different size or direction than that measured on standard x-rays. Corrective changes in hallux valgus surgery are complex, including angular and translational changes at several levels and in several joints in order to produce a clinical resultant. Rotational changes can be evaluated with RSA. Although RSA in an optimal situation is very accurate, it is still limited to a laboratory setting.

Female↗
PubMed2005

Comparison of digital and conventional radiostereometric image analysis in an ankle phantom model.

BACKGROUND AND AIMS: Radiostereometric analysis (RSA) allows accurate three-dimensional measurements of micromotion in skeletal structures. The current RSA techniques are based on the analysis of scanned plain films. This study was undertaken to compare digital filmless RSA technique to conventional scanning technique using a phantom model of the ankle mortise. MATERIAL AND METHODS: In the first experiment, the relative displacement of the markers inserted to the fibula in relation to the markers inserted to the tibia was studied by means of double examinations and the precision of DICOM images were compared to scanned images of printed radiographs. In the second experiment, the film pair of double examination was re-imported or re-scanned and self-compared in order to show merely the error related to the image processing. RESULTS: The precision of RSA using scanned images of printed radiographs was compatible to DICOM images. However, the mean error of rigid body fitting (ME) values were significantly lower in use of DICOM images compared with scanned radiographs, indicating less deformation of rigid body segments in filmless analysis. CONCLUSIONS: Precision of the RSA method was improved under the completely filmless environment. Therefore, this technique can be recommended for clinical studies of radiostereometric analysis.

Ankle Joint↗
PubMed2006

RSA applications in monitoring of fracture healing in clinical trials.

Radiostereometric analysis (RSA) was originally developed as a method for performing highly accurate three-dimensional measurements in vivo over time from sequential radiographs. Since its introduction over twenty years ago, the RSA method has proven itself as a powerful tool with numerous orthopaedic applications. RSA has been used extensively in studies of prosthetic fixation and has been shown to be the method of choice for these studies. RSA has, however, also been successfully applied to a limited number of studies examining fracture healing, namely in fractures of the radius, ankle, tibial plateau, trochanter and femoral neck, as well as studies of bone healing following spinal fusion and tibial osteotomies. RSA follow-up of a fracture will provide definitive demonstration of the exact time of union, i.e. the achievement of fracture stability. This information can be invaluable in randomized clinical trials of fracture treatment. Phantom model studies have proven useful for effective preoperative planning and interpretation of RSA results. The RSA method is a highly accurate, precise and safe objective method for studying fracture healing in clinical trials. The RSA method may serve as a scientific tool to accurately evaluate the significance of supporting novel biomaterials for the early stability and the rate of healing in fractures.

Fracture Healing↗
PubMed2004

Applications of 3D imaging in orthodontics: part I.

Part I of this paper describes the background, general concepts, available techniques and the clinical applications of recording external craniofacial morphology in three dimensions. Part II explores the different 3D techniques of imaging the dental arches, and their possible uses in orthodontic diagnosis and treatment.

Cephalometry↗
PubMed1986

Roentgen stereometry in the study of craniofacial anomalies--the state of the art in Sweden.

The paper is a review of ten years' experience with the method for Roentgen Stereophotogrammetric Analysis (RSA) which was presented by Selvik in 1974. The RSA was developed for the study of bone displacement in three dimensions and intended for clinical use. The accuracy of the recordings is about 0.1 degrees for rotations about and 0.05 mm for translations along any one of the three cardinal axes of the head. The method, based on the use of metallic implants, is essentially individual. Some results from our stereometric studies of patients with cleft lip and palate, hemifacial microsomia, craniofacial dysostosis (Crouzon syndrome) and dysgnathia are presented. The recordings concern the direction, the rate, and the amount of articular growth in the craniofacial sutures and the temporomandibular joints (TMJs). The information obtained is thus highly relevant to treatment planning and follow-up in craniofacial anomalies.

Child, Preschool↗
PubMed1987

Growth study including stereophotogrammetry of a pair of monozygotic twins, one having a cleft lip and palate.

This report is a serial growth study of a pair of monozygotic twin boys, one of whom suffered from a bilateral cleft of the lip and a unilateral cleft of the palate. Annual records for height and weight were registered from seven years eight months to 18 years 0 months. Soft tissue facial growth was also measured annually using short base stereophotogrammetry (Burke, 1967). Growth and development of the dentition was recorded as orthodontic study models at less frequent intervals. Measurements derived from the facial maps allowed not only measurement of soft tissue growth changes in the face, but also of surgical change to both lips related to an Abbe flap procedure carried out for the cleft twin. All changes are compared with those occurring in his monozygotic twin.

Adolescent↗
PubMed1992

Serial observation of asymmetry in the growing face.

Three children suffering from facial asymmetry were observed annually using facial stereophotogrammetry before, during, and after their general skeletal adolescent growth spurt. Stereophotogrammetry allows accurate three-dimensional measurements between identifiable facial landmarks. Five pairs of bilateral parameters connecting external canthi and angles of the mouth to alae and tip of nose, and to each other, allowed a positive sign (right-side larger) or a negative (left-side larger) assessment of parameter asymmetry. Their total, taking sign into account, assessed mid-facial asymmetry. Serial observation showed that: (1) in patient no. 1 suffering from post-traumatic condylar hypoplasia, the facial asymmetry resolved; (2) in patient no. 2 suffering from unilateral facial hypoplasia, the asymmetry, which was severe, reduced with adolescence, but did not resolve; (3) in patient no. 3 suffering from fibro-osseous dysplasia of left maxilla, the asymmetry was reduced by surgery, but the full effects of the surgery were not measurable until over 1 year after operation; subsequently, the asymmetry began to increase again.

Adolescent↗
PubMed1989

Kinematics of the ankle and foot. In vivo roentgen stereophotogrammetry.

Roentgen stereophotogrammetric analysis has been used to study ankle/foot kinematics in eight healthy volunteers. All the joints between the tibia and the first metatarsal as well as the talo-calcaneal and tibio-fibular joints were analysed in input plantar flexion/dorsiflexion and pronation/supination of the foot as well as internal/external rotation of the leg. The findings included the following: INDIVIDUAL JOINTS 1. The joint axis of the talo-crural joint varied with varying kinds of input motion. Substantial amounts of rotation occurred about axes close to the vertical; this occurred particularly when the input motion was in the internal rotation part of the arc of leg rotation and in pro-/supination of the foot. 2. The total amount of rotation in the talo-calcaneal joint was small in internal rotation of the leg and in pronation of the foot compared to external rotation of the leg and supination of the foot. 3. The talo-navicular joint showed a limited ball-and-socket joint pattern in all subjects. The total amounts of rotation were larger than in the talo-calcaneal joint in all subjects. Plantar flexion axes were more transverse than the axes seen in other kinds of input motion. 4. The talo-calcaneal and talo-navicular joint axes were seldom parallel, indicating that these joints do not necessarily behave as a simple hinge. JOINT INTERACTION Joint interaction varied in different qualities of input motion. Plantar flexion induced rotation in the talo-crural joint, and to some extent in the joints of the arch. Dorsiflexion mainly induced talo-crural joint motion. Pronation/supination induced motion in all joints. The distal joints of the arch displayed more rotation in pronation than in supination, while the talo-calcaneal joint showed less motion in pronation than in supination. Internal leg rotation induced little rotation in the joints of the ankle/foot complex. External rotation induced external rotation, dorsiflexion, and supination in the talo-navicular and talo-calcaneal joints. The distal joints of the arch displayed compensatory plantar flexion and pronation. TRANSFERRAL OF ROTATION The ankle/foot complex showed ability to transform leg rotation into pro-/supination and vice versa. This function was most pronounced in external leg rotation. MOTIONS OF THE FIBULA The fibula showed consistent lateral and posterior translation from input plantar flexion to dorsiflexion of the foot.

Adult↗
PubMed1995

Biomechanical effects of transoral odontoidectomy.

The acute biomechanical effects of transoral odontoidectomy were studied by using qualitative and quantitative methods to assess atlantoaxial motion. In vitro biomechanical testing was performed on the upper cervical spines of eight baboon and five human cadaveric specimens. Using an unconstrained testing apparatus, we performed a flexibility method of testing. Physiological range loading was applied to atlantoaxial specimens, and three-dimensional motion was analyzed with stereophotogrammetry. Force-deformation relationships were delineated in intact specimens and again after surgical removal of the anterior C1 arch, odontoid process, and transverse atlantal ligament. We studied the total range of rotational and linear motions, the behavior of the neutral zone and elastic zone, the flexibility coefficients, and the instantaneous axes of rotation during flexion, extension, bilateral lateral bending, and bilateral axial rotation. Odontoidectomy produced several distinct alterations in motion and in force-deformation responses at C1-C2 that were almost identical in the baboon and human specimens. After odontoidectomy, the atlas developed significantly increased translational movements, which were most prominent in the anteroposterior direction. The total angular range of motion increased significantly during flexion, extension, and lateral bending but not during axial rotation. When the total range of motion was altered, the neutral zone was affected selectively and the elastic zone was spared. Surgery produced mobile, widely spread, unconstrained instantaneous axes of rotation that were in a constrained, fixed position in intact specimens. Clinically, transoral odontoidectomy may predispose patients to spinal instability. Even if acute spinal instability is not apparent, the patients may be susceptible to the delayed effects of the surgery because of the altered anatomy and biomechanical responses.

Aged↗
PubMed1995

Echolocation call structure and intensity in five species of insectivorous bats.

Echolocation call intensity was measured in the laboratory for five species of British insectivorous bats in free flight and in the hand. All species showed similar call intensities of between 80 and 90 dB peSPL (peak equivalent SPL) at 1 m during flight except Plecotus auritus, whose call intensity was between 68 and 77 dB peSPL at 1 m. Calls from stationary bats were about 13 dB less intense than calls during flight. A method is proposed to measure the root mean square (rms) amplitude of echolocation calls and, hence, to calculate the energy flux density of the call. The constant-frequency calls of Rhinolophus hipposideros have energy flux densities approximately ten times higher than those of bats using frequency-modulated calls as a result of their longer durations and lower crest factors. It is argued that the low-intensity calls of P. auritus allow it to approach tympanate moths more closely before triggering their escape response.

Animals↗
PubMed2001

Three-dimensional kinematics of skeletal elements in avian prokinetic and rhynchokinetic skulls determined by Roentgen stereophotogrammetry.

Several different types of cranial kinesis are present within modern birds, enabling them to move (part of) the upper bill relative to the braincase. This movement of the upper bill results from movement of the quadrate and the pterygoid-palatine complex (PPC). The taxon Palaeognathae is characterised by a very distinct PPC and a special type of cranial kinesis (central kinesis) that is very different from that found in the Neognathae. This has led some authors to hypothesise that there is a functional relationship between the morphology of the PPC and the type of cranial kinesis. This hypothesis is tested here by analysing the movement pattern of both the upper bill and the PPC in birds with three different types of cranial kinesis: prokinesis, distal rhynchokinesis and central rhynchokinesis. Movement patterns were determined using a Roentgen stereophotogrammetry method, which made it possible to detect very small displacements (0.5 mm) of bony elements in three dimensions, while the jaw muscles and ligaments remained intact. We found that in all types of kinesis investigated the movements of the quadrate, jugal bars and PPC are similar. Movement of the quadrate is transferred to the upper beak by the jugal bar and the PPC, which moves almost exclusively forwards and backwards, thereby elevating or depressing the upper bill. The differences between the types of kinesis lie only in the position of the point of rotation. These findings indicate that there is no correlation between the specific morphology of the PPC and the type of cranial kinesis. Several other factors, including the external forces applied during food acquisition, may influence the morphology of the PPC. Differences in PPC morphology therefore appear to be the result of different functional demands acting on the system simultaneously but with different strengths, depending on the species.

Animals↗
PubMed2004

Muscle forces analysis in the shoulder mechanism during wheelchair propulsion.

This study combines an ergometric wheelchair, a six-camera video motion capture system and a prototype computer graphics based musculoskeletal model (CGMM) to predict shoulder joint loading, muscle contraction force per muscle and the sequence of muscular actions during wheelchair propulsion, and also to provide an animated computer graphics model of the relative interactions. Five healthy male subjects with no history of upper extremity injury participated. A conventional manual wheelchair was equipped with a six-component load cell to collect three-dimensional forces and moments experienced by the wheel, allowing real-time measurement of hand/rim force applied by subjects during normal wheelchair operation. An ExpertVision six-camera video motion capture system collected trajectory data of markers attached on anatomical positions. The CGMM was used to simulate and animate muscle action by using an optimization technique combining observed muscular motions with physiological constraints to estimate muscle contraction forces during wheelchair propulsion. The CGMM provides results that satisfactorily match the predictions of previous work, disregarding minor differences which presumably result from differing experimental conditions, measurement technologies and subjects. Specifically, the CGMM shows that the supraspinatus, infraspinatus, anterior deltoid, pectoralis major and biceps long head are the prime movers during the propulsion phase. The middle and posterior deltoid and supraspinatus muscles are responsible for arm return during the recovery phase. CGMM modelling shows that the rotator cuff and pectoralis major play an important role during wheelchair propulsion, confirming the known risk of injury for these muscles during wheelchair propulsion. The CGMM successfully transforms six-camera video motion capture data into a technically useful and visually interesting animated video model of the shoulder musculoskeletal system. The CGMM further yields accurate estimates of muscular forces during motion, indicating that this prototype modelling and analysis technique will aid in study, analysis and therapy of the mechanics and underlying pathomechanics involved in various musculoskeletal overuse syndromes.

Adult↗
PubMed2004

Evaluation of three pose estimation algorithms for model-based roentgen stereophotogrammetric analysis.

Model-based roentgen stereophotogrammetric analysis (RSA) uses a three-dimensional surface model of an implant in order to estimate accurately the pose of that implant from a stereo pair of roentgen images. The technique is based on minimization of the difference between the actually projected contour of an implant and the virtually projected contour of a model of that same implant. The advantage of model-based RSA over conventional marker-based RSA is that it is not necessary to attach markers to the implant. In this paper, three pose estimation algorithms for model-based RSA are evaluated. The algorithms were assessed on the basis of their sensitivities to noise in the actual contour, to the amount of drop-outs in the actual contour, to the number of points in the actual contour and to shrinkage or expansion of the actual contour. The algorithms that were studied are the iterative inverse perspective matching (IIPM) algorithm, an algorithm based on minimization of the difference (DIF) between the actual contour and the virtual contour, and an algorithm based on minimization of the non-overlapping area (NOA) between the actual and virtual contour. The results of the simulation and phantom experiments show that the NOA algorithm does not fulfil the high accuracy that is necessary for model-based RSA. The IIPM and DIF algorithms are robust to the different distortions, making model-based RSA a possible replacement for marker-based RSA.

Algorithms↗