Biomedical subjects

F Catani

Publications and source records attributed to F Catani.

At least 19 recordsLinked to original sources

PubMed2001

Computer-assisted design of the sagittal shapes of a ligament-compatible total ankle replacement.

The poor results of total ankle replacement have been attributed to the inability of designers to restore adequately the critical mutual function of the ligaments and the articular surfaces. The purpose of this study was to design sagittal shapes of the articular surfaces for a new ankle prosthesis to be compatible with the geometry of the retained ligamentous structures. Several ligament-compatible pairs of articular surfaces were tested using a computerised version of a four-bar linkage model. The kinematics of the ankle when replaced by non-conforming two-component and by fully conforming three-component designs with either flat, concave or convex tibial surfaces were assessed by the model. A ligament-compatible convex-tibia fully-congruent three-component prosthesis showed the best features. The three-component prosthesis allows complete congruence over the entire range of flexion. A convex shape for the tibial arc was preferred because of the better degree of entrapment of the meniscal bearing. A 5 cm convex-tibia arc radius gave 2 mm entrapment together with 9.8 mm of tibial bone cut. Ligament elongation imposed by full congruence of the articular surfaces was less than 0.03% of the original length. The original patterns of joint kinematics and ligament tensioning are closely restored in the joint replaced by the proposed prosthesis.

Ankle Joint↗

PubMed2000

Analysis of ground reaction forces by means of wavelet transform.

OBJECTIVE: To identify details of clinical relevance in ground reaction forces by means of wavelet transform. DESIGN: A retrospective analysis of gait tests performed by total knee replacement patients and a control population has been performed. METHODS: The ground reaction forces have been processed by means of wavelet transform. Results of the wavelet analysis are represented, in a time-frequency plane, by tiles. These are coloured in different grey levels associated to the values of a suitable energy function of the expansion coefficients, resulting from the wavelet transform. RESULTS: The high frequency tiles revealed the presence of irregularities with clinical significance in the first part of the stance phase. These transients in ground reaction forces are described in a quantitative manner allowing to monitor their evolution during the patient observation time. The heel strike transient has been identified by the tile representation of the vertical component of ground reaction forces and confirmed by its correlation with corresponding irregularities in the other components. CONCLUSIONS: The tile representation allows to detect and to quantify details not easily perceivable by the examiner through traditional techniques. The wavelet transform seems particularly appealing for clinical applications such as outcome assessment or treatment evaluation and can assist in the definition of normative models of ground reaction forces. The effectiveness of the procedure suggest to try to automate it. RELEVANCE: The tile representation allows to identify and to keep the records of ground reaction forces clinically significant details, such as heel strike transient.

Arthroplasty, Replacement, Knee↗

PubMed2000

Cruciate ligament forces in the human knee during rehabilitation exercises.

OBJECTIVE: To determine the cruciate ligament forces occurring during typical rehabilitation exercises.Design. A combination of non-invasive measurements with mathematical modelling of the lower limb.Background. Direct measurement of ligament forces has not yet been successful in vivo in humans. A promising alternative is to calculate the forces mathematically. METHODS: Sixteen subjects performed isometric and isokinetic or squat exercises while the external forces and limb kinematics were measured. Internal forces were calculated using a geometrical model of the lower limb and the "dynamically determinate one-sided constraint" analysis procedure. RESULTS: During isokinetic/isometric extension, peak anterior cruciate ligament forces, occurring at knee angles of 35-40 degrees, may reach 0.55x body-weight. Peak posterior cruciate ligament forces are lower and occur around 90 degrees. During isokinetic/isometric flexion, peak posterior cruciate forces, which occur around 90 degrees, may exceed 4x body-weight; the anterior cruciate is not loaded. During squats, the anterior cruciate is lightly loaded at knee angles up to 50 degrees, after which the posterior cruciate is loaded. Peak posterior cruciate forces occur near the lowest point of the squat and may reach 3.5x body-weight. CONCLUSIONS: For anterior cruciate injuries, squats should be safer than isokinetic or isometric extension for quadriceps strengthening, though isokinetic or isometric flexion may safely be used for hamstrings strengthening. For posterior cruciate injuries, isokinetic extension at knee angles less than 70 degrees should be safe but isokinetic flexion and deep squats should be avoided until healing is well-advanced. RELEVANCE: Good rehabilitation is vital for a successful outcome to cruciate ligament injuries. Knowledge of ligament forces can aid the physician in the design of improved rehabilitation protocols.

Adult↗

PubMed2000

The role of the passive structures in the mobility and stability of the human ankle joint: a literature review.

The mobility and stability of the ankle joint have been extensively investigated, but many critical important issues still need to be elucidated. However, there seems to be a general agreement on several important observations. A more isometric pattern of rotation for the calcaneofibular and the tibiocalcaneal ligaments with respect to all the others has been reported. Many recent studies have found changing positions of the instantaneous axis of rotation, suggesting that the hinge joint concept is an oversimplification for the ankle joint. A few recent works have also claimed anterior shift of the contact area at the tibial mortise during dorsiflexion, which would imply combined rolling and sliding motion at this joint. Many findings from the literature support the view of a close interaction between the geometry of the ligaments and the shapes of the articular surfaces in guiding and stabilizing motion at the ankle joint.

Ankle Joint↗

PubMed2000

Muscle performance about the knee joint in patients who had distal femoral replacement after resection of a bone tumor. An objective study with use of gait analysis.

BACKGROUND: The treatment of a malignant bone tumor in the distal aspect of the femur often requires great sacrifice of bone and muscle. The extent of quadriceps removal has been reported to influence the long-term functional efficiency of a patient's gait. The objective of the present study was to determine gait function as it relates to the residual quadriceps strength and to the specific component or components of the quadriceps removed in patients treated with total knee replacement because of a malignant bone tumor in the distal aspect of the femur. METHODS: Sixteen patients were evaluated after implantation of a modular hinged cementless knee prosthesis. The patients were assigned to two groups on the basis of the different components of the quadriceps muscle that were resected. Group 1 consisted of five patients who had removal of the vastus medialis and the vastus intermedius and two who had removal of the vastus medialis only. Group 2 consisted of nine patients who had removal of the vastus lateralis and the vastus intermedius. Residual muscular strength about the treated knee was measured by voluntary maximum contraction isometric testing. Foot-ground reaction forces, kinematic and kinetic findings, and electromyographic activity during free-speed walking were recorded. RESULTS: The kinematic study showed that the patients in Group 1 tended to have a stiff-knee gait during stance, whereas those in Group 2 (in which the vastus medialis was spared) had a more regular flexion-extension knee pattern. Electromyographic findings showed that a higher percentage of patients in Group 1 had reduced or absent rectus femoris activity during the loading response. Compared with the contralateral side, knee-extension strength in the treated limb was decreased in both groups. However, there were no significant differences between the groups with respect to the pattern of strength loss. CONCLUSIONS: Good gait function can be achieved in patients with a distal femoral tumor that is treated with distal femoral resection, partial excision of the quadriceps, and total knee arthroplasty with insertion of a hinged prosthesis. Patients in whom the vastus lateralis and vastus intermedius were removed had better gait performance and a more physiological knee-loading pattern than did patients in whom the vastus medialis was removed.

Adult↗

PubMed1999

Validation of a functional method for the estimation of hip joint centre location.

The present study assesses the accuracy with which the subject specific coordinates of the hip joint centre (HJC) in a pelvic anatomical frame can be estimated using different methods. The functional method was applied by calculating the centre of the best sphere described by the trajectory of markers placed on the thigh during several trials of hip rotations. Different prediction methods, proposed in the literature and in the present investigation, which estimate the HJC of adult subjects using regression equations and anthropometric measurements, were also assessed. The accuracy of each of the above-mentioned methods was investigated by comparing their predictions with measurements obtained on a sample of 11 male adult able-bodied volunteers using roentgen stereophotogrammetric analysis (RSA), assumed to provide the true HJC locations. Prediction methods estimated the HJC location at an average rms distance of 25-30 mm. The functional method performed significantly better and estimated HJCs within a rms distance of 13 mm on average. This result may be confidently generalised if the photogrammetric experiment is carefully conducted and an optimal analytical approach used. The method is therefore suggested for use in motion analysis when the subject's hip range of motion is not limited. In addition, the facts that it is not an invasive technique and that it has relatively small and un-biased errors, make it suitable for regression equations identification with no limit to sample size and population typology.

Adult↗

PubMed1999

Kinematics of the human ankle complex in passive flexion; a single degree of freedom system.

The restoration of original range and pattern of motion is the primary goal of joint replacement and ligament reconstruction. The objective of the present work is to investigate whether or not a preferred path of joint motion at the intact human ankle complex is exhibited during passive flexion. A rig was built to move the ankle complex through its range of flexion while applying only the minimum necessary load to drive ankle flexion. Joint motion was constrained only by the articular surfaces and the ligaments. The movements of the calcaneus, talus and fibula relative to the stationary tibia in seven cadaveric specimens were tracked with a stereophotogrammetric system. It was shown that the calcaneus follows a unique path of unresisted coupled motion relative to the tibia and that most of the motion occurred at the ankle, with little motion at the subtalar level. The calcaneofibular and the tibiocalcaneal ligaments showed near-isometric pattern of rotations. All specimens showed motion of the axis of rotation relative to the bones. Deviations from the unique path due to the application of load involved mostly subtalar motion and were resisted. The ankle complex exhibits one degree of unresisted freedom, the ankle behaving as a single degree of freedom mechanism and the subtalar as a flexible structure. We deduced that the calcaneofibular and tibiocalcaneal ligaments together with the articular surfaces guide ankle passive motion, other ligaments limit but do not guide motion.

Ankle Joint↗

PubMed1999

A geometric model of the human ankle joint.

A two-dimensional four-bar linkage model of the ankle joint is formulated to describe dorsi/plantarflexion in unloaded conditions as observed in passive tests on ankle complex specimens. The experiments demonstrated that the human ankle joint complex behaves as a single-degree-of-freedom system during passive motion, with a moving axis of rotation. The bulk of the movement occurred at the level of the ankle. Fibres within the calcaneofibular and tibiocalcaneal ligaments remained approximately isometric. The experiments showed that passive kinematics of the ankle complex is governed only by the articular surfaces and the ligaments. It was deduced that the ankle is a single-degree-of-freedom mechanism where mobility is allowed by the sliding of the articular surfaces upon each other and the isometric rotation of two ligaments about their origins and insertions, without tissue deformation. The linkage model is formed by the tibia/fibula and talus/calcaneus bone segments and by the calcaneofibular and tibiocalcaneal ligament segments. The model predicts the path of calcaneus motion, ligament orientations, instantaneous axis of rotation, and conjugate talus surface profile as observed in the experiments. Many features of ankle kinematics such as rolling and multiaxial rotation are elucidated. The geometrical model is a necessary preliminary step to the study of ankle joint stability in response to applied loads and can be used to predict the effects of changes to the original geometry of the intact joint. Careful reconstruction of the original geometry of the ligaments is necessary after injury or during total ankle replacement.

Ankle Injuries↗

PubMed1999

Flat foot functional evaluation using pattern recognition of ground reaction data.

OBJECTIVE: Main purpose of this study was to apply quantitative gait analysis and statistical pattern recognition as clinical decision-making aids in flat foot diagnosis and post-surgery monitoring. DESIGN: Statistical pattern recognition techniques were applied to discriminate between normal and flat foot populations through ground reaction force measurements; ground reaction forces time course was assumed as a sensible index of the foot function. BACKGROUND: Gait analysis is becoming recognized as an important clinical tool in orthopaedics, in pre-surgery planning, post-surgery monitoring and in a posteriori evaluation of different treatment techniques. Statistical pattern recognition techniques have been utilized with success in this field to identify the most significant variables of selected motor functions in different pathologies, and to design classification rules and quantitative evaluation scores. METHODS: Ground reaction forces were recorded during free speed barefoot walks on 28 healthy subjects, and 28 symptomatic flexible flat foot children selected for surgical intervention. A new feature selection algorithm, based on heuristic optimization, was applied to select the most discriminant ground reaction forces time samples. A two-stage pattern recognition system, composed by three linear feature extractors, one for each ground reaction force component, and a linear classifier, was designed to classify the feet of each subject using the selected features. The output of the classifier was used to define a functional score. RESULTS: The classifier assigned the ground reaction force patterns performed by each subject into the right class with an estimated error of 15%, corresponding to an assignment error for each subject's foot of 9%. The most discriminant ground reaction forces time samples selected are in full agreement with the pathophysiology of the symptomatic flexible flat foot. The obtained score was utilized to monitor the 1 and 2 years post-operative functional recovery of two differently treated subgroups of 32 flexible flat foot subjects. CONCLUSIONS: Statistical pattern recognition techniques are promising tools for clinical gait analysis; the obtained score provides important functional information that could be used as a further aid in the clinical evaluation of flat foot and different surgical treatment techniques. RELEVANCE: Symptomatic flexible flat foot surgical decision making is frequently difficult because of the lack of objective criteria to assess functional abnormalities of the foot/ankle complex. Gait analysis and statistical pattern recognition can give us parameters with which to characterize "functional" flat foot. Moreover, we can objectively follow up the recovery of the foot/ankle complex function after surgical treatment.

Algorithms↗

PubMed1999

An anatomically based protocol for the description of foot segment kinematics during gait.

OBJECTIVE: To design a technique for the in vivo description of ankle and other foot joint rotations to be applied in routine functional evaluation using non-invasive stereophotogrammetry. DESIGN: Position and orientation of tibia/fibula, calcaneus, mid-foot, 1st metatarsal and hallux segments were tracked during the stance phase of walking in nine asymptomatic subjects. Rigid clusters of reflective markers were used for foot segment pose estimation. Anatomical landmark calibration was applied for the reconstruction of anatomical landmarks. BACKGROUND: Previous studies have analysed only a limited number of joints or have proposed invasive techniques. METHODS: Anatomical landmark trajectories were reconstructed in the laboratory frame using data from the anatomical calibration procedure. Anatomical co-ordinate frames were defined using the obtained landmark trajectories. Joint co-ordinate systems were used to calculate corresponding joint rotations in all three anatomical planes. RESULTS: The patterns of the joint rotations were highly repeatable within subjects. Consistent patterns between subjects were also exhibited at most of the joints. CONCLUSION: The method proposed enables a detailed description of ankle and other foot joint rotations on an anatomical base. Joint rotations can therefore be expressed in the well-established terminology necessary for their clinical interpretation. RELEVANCE: Functional evaluation of patients affected by foot diseases has recently called for more detailed and non-invasive protocols for the description of foot joint rotations during gait. The proposed method can help clinicians to distinguish between normal and pathological pattern of foot joint rotations, and to quantitatively assess the restoration of normal function after treatment.

Adult↗

PubMed1999

A model-based method for the reconstruction of total knee replacement kinematics.

A better knowledge of the kinematics behavior of total knee replacement (TKR) during activity still remains a crucial issue to validate innovative prosthesis designs and different surgical strategies. Tools for more accurate measurement of in vivo kinematics of knee prosthesis components are therefore fundamental to improve the clinical outcome of knee replacement. In the present study, a novel model-based method for the estimation of the three-dimensional (3-D) position and orientation (pose) of both the femoral and tibial knee prosthesis components during activity is presented. The knowledge of the 3-D geometry of the components and a single plane projection view in a fluoroscopic image are sufficient to reconstruct the absolute and relative pose of the components in space. The technique is based on the best alignment of the component designs with the corresponding projection on the image plane. The image generation process is modeled and an iterative procedure localizes the spatial pose of the object by minimizing the Euclidean distance of the projection rays from the object surface. Computer simulation and static/dynamic in vitro tests using real knee prosthesis show that the accuracy with which relative orientation and position of the components can be estimated is better than 1.5 degrees and 1.5 mm, respectively. In vivo tests demonstrate that the method is well suited for kinematics analysis on TKR patients and that good quality images can be obtained with a carefully positioning of the fluoroscope and an appropriate dosage. With respect to previously adopted template matching techniques, the present method overcomes the complete segmentation of the components on the projected image and also features the simultaneous evaluation of all the six degrees of freedom (DOF) of the object. The expected small difference between successive poses in in vivo sequences strongly reduces the frequency of false poses and both the operator and computation time.

Algorithms↗

PubMed1999

Myoelectric activation pattern during gait in total knee replacement: relationship with kinematics, kinetics, and clinical outcome.

Gait usually presents an excellent improvement after total knee replacement. Nevertheless, some abnormalities persist even after a long period of time. The abnormal knee patterns have been attributed to several possible causes, such as implant geometry and surgical technique, posterior cruciate ligament sparing/sacrificing, preoperative "stiff-knee" pattern due to pain and altered biomechanics, weakness of the extensor muscles, preoperative arthritic pattern, proprioceptive deficiency, and multijoint degenerative involvement. Cocontraction of the knee flexors and extensors is a common strategy adopted to reduce strain and shear forces at the joint, but it increases compressive forces and joint loading. Even in patients with an excellent functional score, the duration of the implant may be compromised by an altered neuromuscular control of the knee. In this paper, we report a single case study carried out over two years on a patient that underwent total knee replacement. The aim of this work is to show that quantitative gait analysis is essential to augment the understanding of the mechanisms underlying gait, thus enabling clinicians to adapt the rehabilitation program to the specific patient. Although the limits of single case reports are obvious, we believe that this evaluation methodology could be beneficial for assessing the effectiveness of rehabilitation programs aimed at achieving an active control of the knee during gait through a correct muscular activation pattern.

Biomechanical Phenomena↗

PubMed1999

Analysis of function after intra-articular fracture of the os calcis.

Fractures of the os calcis with intra-articular involvement can cause difficulty in treatment and can result in abnormal function throughout the ankle-foot complex. We evaluated the function of the ankle-foot complex and the overall gait pattern after fracture of the os calcis, and we compared the results of surgical and nonsurgical treatment. Those in whom the geometry of the os calcis and joint was restored by reconstructive surgery had better compensation of gait and a better clinical-functional score. Complex disturbances in gait were found in the group of patients that did not undergo open reduction or internal fixation.

Adult↗

PubMed1994

Surgical repair of achilles tendon ruptures using polypropylene braid augmentation.

Surgical repair in fresh rupture of the Achilles tendon should be considered in active patients and athletes to restore their preinjury level of activity. Fifteen cases of Achilles tendon rupture underwent surgical repair using interpositional augmentation. This technique provides an immediate mechanical strength of the repair, avoiding the need for a postoperative plaster cast and allowing immediate motion of the ankle. No wound infection, scar adherence of the skin to the tendon, or rerupture of the tendon is present in this series. All patients were subjectively satisfied with the results and returned to their preinjury level of activity. Objectively, isokinetic assessment revealed no significant difference, as per t-test evaluation (P < .05), between the operated leg and the controlateral one.

Achilles Tendon↗

PubMed1994

Osteoid osteoma of the lateral cuneiform bone.

An unusual case of osteoid osteoma is reported emphasizing the necessity of a careful history and physical examination combined with an adequate imaging supply. Treatment was surgical with an en bloc excision of the lesion.

Adult↗

PubMed1993

Gait analysis in patients after Van Nes rotationplasty.

Gait was analyzed through kinetic, kinematic, and temporal-distance parameters assessment to evaluate the functional performance of ten children treated by the classical Van Nes rotationplasty (VNR). Van Nes rotationplasty is a surgical procedure, which permits the conversion of the ankle joint into a "pseudo-knee" joint. The data were compared with measurements of a normal population of ten healthy subjects. Significant differences with respect to the normal were found in stride duration, stride length, cadence, velocity, and stance-swing ratio, and in ground-reaction forces parameters, which define the propulsive phase in the prosthetic side and the acceptance phase in the sound side. There were differences in some kinematic parameters as well. Van Nes rotationplasty is acceptable from a biomechanical-functional point of view, particularly with respect to the active control of the pseudo-knee, which allows a smooth and coordinate gait pattern.

Adolescent↗

PubMed1992

Kinematic and isokinetic evaluation of patients with flat foot.

In recent years research into joint physiology and biomechanics of movement has employed high-technology instruments to quantify the parameters which determine whether the behavior of a joint or kinematic chain is normal or pathologic. Motion analysis, featuring evaluation of both kinematics and the foot-ground reaction, enables us to measure the temporal and quantitative events of normal and pathologic gaits. The use of motion analysis in the study of flat foot has confirmed the ability to discriminate between "normal" and pathologic. Analysis of these themes has enabled us to follow the temporal evolution of the quantitative parameters both before and after treatment, which can be either surgical or conservative. Evaluation of the kinematic changes and the foot-ground reaction also provides information about the quality and effectiveness of the corrective treatment. For instance, the change in the subtalar alignment following application of an endo-orthotic implant can be targeted for validation by motion analysis. All of the joints comprised in the kinematic chain of the lower limb work together to achieve a symmetrical, rhythmic, and most of all harmonic gait.

Adolescent↗

PubMed1992

Functional evaluation of patients fitted with total knee prostheses.

Degenerative or inflammatory diseases of the knee joint account for a large proportion of diseases affecting the elderly. Treatment aims to eliminate pain, correct the deformity and maintain complete joint mobility. In cases of total joint degeneration, fitting of a joint prosthesis is the technique currently favoured since elimination of pain and correction of the deformity, accompanied by recovery of joint mobility (the fundamental requirements for normal everyday life) can only be obtained if the knee joint is completely replaced. With the discovery of new materials and increasingly sophisticated knowledge about articular mechanics, the knee prosthesis, although more recent than the hip prosthesis, has become ever more widespread to the point that it now represents an irreplaceable aid in the treatment of this common disease. The clinical results obtained are already stable and particularly encouraging and prosthesis design is sophisticated and accurate. There is, however, still the suspicion that current prostheses can be considered "rudimentary" in comparison with the physiological and biomechanical behaviour of the human joint. We therefore wanted to begin an evaluation using a gait analysis system to assess patients fitted with knee prostheses. The first impressions gained in this study are the subject of this article.

Activities of Daily Living↗