Search PubMed⌕ Search

Biomedical subjects

M Marcacci

Publications and source records attributed to M Marcacci.

At least 19 recordsLinked to original sources
PubMed2006

Neoligamentization process of BTPB used for ACL graft: histological evaluation from 6 months to 10 years.

Following anterior cruciate ligament (ACL) reconstruction with the middle third part patellar tendon, the graft undergoes histological rearrangement due to biomechanical action, which transforms it into a structure similar to the normal ACL. The purpose of our study was to make a qualitative and quantitative histological evaluation, by transmission electron microscopy (TEM), of the neoligamentization process of a bone-patellar tendon-bone (BTPB) graft used as pro-ACL at different follow-up times. We analysed the ultrastructure of collagen fibrils by focusing on their size and distribution with respect to a normal patellar tendon and a normal ACL used as controls. Our results showed that up to 24 months follow-up, progressive ultrastructural changes towards the normal ACL were observed. At longer times after surgery (48 and 120 months) no further changes were evident and the ultrastructure showed a marked reduction in large fibrils, which was typical of the control patellar tendon, and a significant increase in small fibrils. The ultrastructure seemed to combine fibrils from two different morphological units. The BPTB graft used as ACL underwent a transformation process for up to two years. After that period the transformation ceased and for ten years failed to reach the ultrastructural aspect of a normal ACL. However, from an architectural point of view the graft was slowly transformed into a structure similar to ACL with respect to the different mechanical stresses the ligament has to sustain.

Adolescent↗
PubMed2006

New intraoperative protocol for kinematic evaluation of ACL reconstruction: preliminary results.

A real improvement in anterior cruciate ligament (ACL) surgery would be achieved if a global kinematic evaluation of graft performance could be made during surgery. A quantitative evaluation of all residual instabilities would be helpful in the evaluation of graft performances. This paper describes a new protocol for an accurate and extensive computer-assisted in vivo evaluation of joint laxities during ACL reconstruction. Fifteen in vivo kinematic evaluations during ACL reconstruction were performed using an optical localizer and custom software. The capability of the protocol was studied by analyzing the accuracy and repeatability of the results, the ergonomics of the setup, time taken, interactions with the surgical steps, and efficacy of the acquisitions. Repeatability of the tests, at maximum force, remained under 1 mm/2 degrees . Repeatability in tibia position and orientation was lower than 1 mm/4 degrees . Secondary laxities during stress tests remained under 2 mm/3 degrees . Added time to surgery was about 11 min. ACL graft increased joint stability up to 52% with respect to the preoperative level. The simplicity and morbidity of the test procedure and system was minimally invasive and allowed a quantitative evaluation of knee laxities at time zero. The repeatability of the tests opens the way for future research on in vivo evaluation of different ACL reconstruction techniques, which may lead to a better understanding of associated lesions and their role to the global knee stability.

Adult↗
PubMed2005

Validation of a new protocol for computer-assisted evaluation of kinematics of double-bundle ACL reconstruction.

BACKGROUND: Computer-assisted surgery is useful to increase the precision of anterior cruciate ligament (ACL) surgical procedure, but could be even more important in evaluating the global performance of reconstructed ACL. This paper describes a new protocol for an accurate and extensive computer-assisted evaluation of single- and double-bundle reconstructions of ACL. METHODS: The protocol consists of the acquisition of the leg axes, ACL and graft insertions by a navigation system, and tracking of the knee motion during the classical kinematic test of knee stability. These data are elaborated by computer software in order to compute graft biomechanical behaviour and the knee kinematics and estimate the performance of the intervention. FINDINGS: The proposed protocol was validated on three cadaver knees. It resulted minimally invasive, effective to describe graft kinematic performance and able to provide a 3D reliable description of the reconstructed knee. INTERPRETATION: The protocol is an extension of the present evaluation of computer-assisted packages and includes additional kinematic tests and computations. The scientist-reader can find important details on tested computations to implement a similar computer-assisted procedure for new applications in knee surgery, while the surgeon can find in this procedure a means to improve the evaluation of ACL reconstruction and identify the residual laxity.

Anterior Cruciate Ligament↗
PubMed2005

Cloning, expression, purification, and characterization of Streptococcus pneumoniae IgA1 protease.

The IgA1 protease of Streptococcus pneumoniae is a Zn-metalloproteinase of 1964 amino acids that specifically cleaves the hinge region of IgA1, the predominant class of immunoglobulin present on mucosal membranes. This protease is associated to the bacterial cell surface via an N-terminal membrane anchor. Following proteolysis it is released in several forms of different molecular weight. Here, we describe the cloning, expression, and characterization of the enzymatic activity and immunogenicity of three fragments of IgA1 protease, including a large one lacking only the 103 N-terminal amino acids that constitute a typical prokaryotic signal sequence. Further, a proteolytically inactive mutant was generated by replacement of the glutamate residue with an alanine residue in the active site motif HExxH (1605-1609). This is the first report of recombinant active forms of S. pneumoniae IgA1 protease, which open the possibility of identifying specific inhibitors that could interfere with the mucosal colonization by pneumococcus. Moreover the inactive mutant could be considered as a candidate vaccine component.

Cloning, Molecular↗
PubMed2003

Dynamic in-vivo tibio-femoral and bearing motions in mobile bearing knee arthroplasty.

To determine the tibio-femoral and bearing motions in well functioning mobile bearing total knee arthroplasties, a quantitative analysis by means of fluoroscopy was carried out during stair ascending, chair rising-sitting and step up-down motor tasks. Femoral and tibial component positions were obtained using a CAD-model-based shape matching technique. Direct measurement of mobile bearing motion was carried out by tracking previously inserted tantalum beads. A relatively small motion of the bearing was observed. The advantage of self-alignment claimed for the mobile bearing arthroplasty seems to be confirmed by subject-specific ranges of motion exhibited by these patients. It has also been demonstrated that these total knee arthroplasties, which are not fully conforming in flexion, provide little constraint to antero-posterior motion, leading to a kinematic pattern very similar to an ACL deficient knee.

Activities of Daily Living↗
PubMed2003

Treatment of chronic patellar dislocation with a modified Elmslie-Trillat procedure.

BACKGROUND: This paper describes a modification of the Elmslie-Trillat procedure that is usually performed in severe cases of habitual or recurrent patellar instability. METHODS: Eighteen knees (7 men and 8 women) treated for recurrent or habitual patellar dislocation were evaluated clinically and radiographically at a mean follow-up of 5 years (range 24 months to 9 years). The mean age at follow-up was 26.3 years (range 17-44 years). The IKDC and Kujala and Tegner scores were used for the clinical evaluation. Anteroposterior, lateral and Merchant views were done for radiographic monitoring. When the patella was still unstable during dynamic evaluation after execution of the Elmslie-Trillat procedure, the medial third of the patellar tendon was isolated and harvested with a corresponding 1 cm long and 0.5 cm wide bone plug, maintaining its insertion to the inferior medial side of the patella. This ligament was medialized and put under tension, trying to find a medial insertion that guaranteed patellar stability throughout the full range of motion. RESULTS: IKDC classified 11 knees as A (normal), 4 knees as B (almost normal), 2 knees as C (abnormal) and 1 knee as D (severely abnormal). The Kujala score showed excellent results in 16 knees, 1 fair and 1 poor knee. The mean Tegner score rose from 2 preoperatively to 5 at follow-up. The poor knee presented an over-correction of the congruence angle on radiography. On follow-up radiographs, the parameters were almost completely corrected. Statistical analysis showed a significant correction of radiograph parameters, and significantly worse results in patients who underwent trochleoplasty. CONCLUSION: The technique described tries to achieve a dynamic stability of the patella throughout the full range of motion in severe patellar instability where the Elmslie-Trillat procedure is insufficient. No recurrence of patellar instability has been observed. The stability must be obtained with dynamic control in the initial degrees of flexion, trying to avoid an excessive patellar medialization.

Adolescent↗
PubMed2003

Vascularity and neuroreceptors of the pes anserinus: anatomic study.

The primary aim of this work was to evaluate the neurovascular network of the pes anserinus (PA) at its tibial insertion because the PA is often used for anterior cruciate ligament (ACL) reconstruction. Four fresh cadaver knees were injected with India ink gelatin solution and the arteries that supply blood to the PA were identified; microscopic studies of vessels and nerve fibers were also performed. Superficial and deep branches of the inferior medial genicular artery contribute to an arterial arch that courses deep to the PA insertion. A widespread array of small vessels and nerve fibers penetrate the PA insertion and course along the length of the gracilis and semitendinosus tendons. Computer analysis revealed that the mean diameter of the vessels decreased from 2201 microm at the insertion to 661 microm midway along the length of the tendon (mean tendon length = 17 cm; range = 13-21 cm); the cross-sectional area of the vessels per histologic section decreased from 336.37-137.05 microm(2). This study demonstrates that the PA insertion is well vascularized and richly innervated and that these morphological features continue along the length of the tendons.

Anterior Cruciate Ligament↗
PubMed2003

Muscle activation pattern and gait biomechanics after total knee replacement.

OBJECTIVE: The aim of this study is to evaluate residual muscle function abnormalities after total knee replacement, with respect to gait kinematics and kinetics. DESIGN: Longitudinal study on a follow-up of up to two years. BACKGROUND: Gait usually presents an excellent improvement after total knee replacement. Nevertheless, some kinematics and kinetics abnormalities persist even after a long period of time and they might have implications in long-term prosthesis failure. Additionally, lower limb muscle activity has not been sufficiently studied in the past directly by means of dynamic EMG. METHODS: Nine patients who had a posterior cruciate sparing total knee replacement design were evaluated by means of clinical assessment and gait analysis at the end of rehabilitation trials at six, twelve and twenty four months. EMG from trunk and lower limb muscles was registered and elaborated through a statistical detector for the on-off timing. RESULTS: Gait analysis showed a slow gait, with a "stiff knee gait pattern" and prolonged muscular co-contractions during stance. CONCLUSIONS: Knee kinematics and kinetics abnormalities during loading acceptance after total knee replacement are associated with co-contractions in muscular activation pattern. RELEVANCE: Gait pattern at two years after total knee replacement is deemed unphysiological, potentially dangerous for the implant duration in time and responsible for residual disability in patients. Muscular behavior during daily activities provides insight into the integration of the prosthetic biomechanics within the muscular-skeletal system. This information is of relevance to improve prosthetic design, rehabilitation programs and knee motor performance.

Aged↗
PubMed2002

Arthroscopic autologous chondrocyte transplantation: technical note.

We describe an arthroscopic surgical technique for tissue engineered cartilage grafting. A three-dimensional hyaluronic acid support is used for autologous chondrocyte culturing. The technique reduces morbidity of classic autologous implant and avoids open surgery and the use of a periosteal flap. The procedure includes the advantages of arthroscopic osteochondral grafting without donor site morbidity. With this technique is possible to reduce the patient morbidity, time and cost of surgery.

Adolescent↗
PubMed2001

Micromotion between the half bearings in the interax prosthesis: a roentgen stereophotogrammetric analysis.

We assessed the migration and movement between the half-bearings of the Interax prosthesis in 18 patients using roentgen stereophotogrammetric analysis (RSA). This study showed movements of the tibial component even in successful knee arthroplasty: 17 prostheses migrated only initially and remained stable after 1 year, whereas 1 prosthesis migrated consistently throughout 3-year follow-up. RSA revealed no or minimal displacement between the half-bearings until the 4-year follow-up, confirming that their fixation to the baseplate was adequate. In the case of loosening, a rotation about the longitudinal axis of 1.3 degrees and a medial-lateral translation of 0.5 mm was observed between the half-bearings. Cold flow was revealed by RSA in the posterior region of the medial half-bearing.

Aged↗
PubMed2000

Autologous bone marrow stromal cells loaded onto porous hydroxyapatite ceramic accelerate bone repair in critical-size defects of sheep long bones.

The ability of marrow-derived osteoprogenitor cells to promote repair of critical-size tibial gaps upon autologous transplantation on a hydroxyapatite ceramic (HAC) carrier was tested in a sheep model. Conditions for in vitro expansion of sheep bone marrow stromal cells (BMSC) were established and the osteogenic potential of the expanded cells was validated. Ectopic implantation of sheep BMSC in immunocompromised mice led to extensive bone formation. When used to repair tibial gaps in sheep, cell-loaded implants (n = 2) conducted a far more extensive bone formation than did cell-free HAC cylinders (n = 2) over a 2-month period. In cell-loaded implants, bone formation was found to occur both within the internal macropore space and around the HAC cylinder while in control cell-free implants, bone formation was limited mostly to the outer surface and was not observed in most of the inner pores. As tested in an indentation assay, the stiffness of the complex HAC-bone material was found to be higher in cell-loaded implants compared to controls. Our pilot study on a limited number of large-sized animals suggests that the use of autologous BMSC in conjunction with HAC-based carriers results in faster bone repair compared to HAC alone. Potentially this combination could be used clinically in the treatment of extensive long bone defects.

Animals↗
PubMed2000

Results of the original Putti-Platt procedure for shoulder instability: review of Putti's scholar experience.

Twenty patients who underwent Putti-Platt shoulder capsulorraphy were retrospectively evaluated at long-term follow-up (24-34 years). The aim of this study was to analyse the efficacy and possible degenerative changes associated with this procedure. Patients' charts were reviewed to analyse the pre-operative picture, surgical technique and post-operative program. All patients were re-examined using ASES, Rowe and Lysholm scales. Range of movement (ROM) of the shoulder operated on was compared with the non-operated one. A-P, axillary and outlet views were taken for radiographic control. Samilson criteria were followed to determine the degree of arthrosis. Clinical outcome was satisfactory in 85% of the cases with only three cases with fair results (15%). No recurrence was present in this series. The mean limitation of external rotation in abduction was 9 degrees with respect to the contra-lateral shoulder. Severe degenerative changes were observed in two cases. In conclusion, after a long follow-up period, the Putti-Platt technique has shown highly satisfactory results, with an incidence of loss of motion and joint degeneration changes similar to other procedures.

Adolescent↗
PubMed2000

Intraoperative kinematic protocol for knee joint evaluation.

Although knee kinematics has been investigated widely, no standard, objective evaluation of the kinematics behaviour of the joint is used at present during surgical treatment. We propose a kinematic protocol for a manual intraoperative evaluation of the knee behaviour, with which the range of motion, the 'screw-home' mechanism and knee instabilities could be quantified. The method does not require anatomical landmarks, because it is computed from standard tests used in clinical practice and gives a decomposition of the knee movement comparable to the well known Grood and Suntay analysis [E.S. Grood, W.J. Suntay, A joint coordinate system for the clinical description of three-dimensional motions: application to the knee, J. Biomech. Eng. 105 (1983) 136-144]. We describe the protocol, report the evaluation of its numerical features and provide a comparison with Grood and Suntay method on ten porcine knees.

Animals↗
PubMed2000

A novel mechatronic tool for computer-assisted arthroscopy.

This paper describes a novel mechatronic tool for arthroscopy, which is at the same time a smart tool for traditional arthroscopy and the main component of a system for computer-assisted arthroscopy. The mechatronic arthroscope has a cable-actuated servomotor-driven multi-joint mechanical structure, is equipped with a position sensor measuring the orientation of the tip and with a force sensor detecting possible contact with delicate tissues in the knee, and incorporates an embedded microcontroller for sensor signal processing, motor driving and interfacing with the surgeon and/or the system control unit. When used manually, the mechatronic arthroscope enhances the surgeon's capabilities by enabling him/her to easily control tip motion and to prevent undesired contacts. When the tool is integrated in a complete system for computer-assisted arthroscopy, the trajectory of the arthroscope is reconstructed in real time by an optical tracking system using infrared emitters located in the handle, providing advantages in terms of improved intervention accuracy. The computer-assisted arthroscopy system comprises an image processing module for segmentation and three-dimensional reconstruction of preoperative computer tomography or magnetic resonance images, a registration module for measuring the position of the knee joint, tracking the trajectory of the operating tools, and matching preoperative and intra-operative images, and a human-machine interface that displays the enhanced reality scenario and data from the mechatronic arthroscope in a friendly and intuitive manner. By integrating preoperative and intra-operative images and information provided by the mechatronic arthroscope, the system allows virtual navigation in the knee joint during the planning phase and computer guidance by augmented reality during the intervention. This paper describes in detail the characteristics of the mechatronic arthroscope and of the system for computer-assisted arthroscopy and discusses experimental results obtained with a preliminary version of the tool and of the system.

Arthroscopes↗
PubMed2000

Computer- and robot-assisted total knee replacement: analysis of a new surgical procedure.

This paper describes a nonstandard procedure for total knee replacement (TKR), based on the use of modern tools such as computers, electronic sensors, and robots, to achieve accurate and optimal implant results. The intervention is planned on a standard PC connected to the CT scanner. Dedicated software shows the surgeon limb alignment and knee status and assists in the choice of the best prosthesis. The intervention is then performed with a new device and surgical procedure. At first the femur and the tibia are fixed to the operating table with a special clamp and the knee bones are exposed with the standard technique; then the surgeon digitizes the shape of the joint and the computer transfers the planned surgical strategy to a dedicated surgical robot. Resections are performed by the surgeon on a constrained guide held by the robot. In this paper we summarize the main results on the system performances, and discuss the clinical implications of this new technology in the operating room. Preliminary experiments on cadavers and volunteers show that this methodology can improve the accuracy of the implant to 2.5 mm and 20, reduce operating time and surgical errors, and may represent a challenging alternative methodology for TKR.

Arthroplasty, Replacement, Knee↗
PubMed2000

The mobility of the proximal tibio-fibular joint. A Roentgen Stereophotogrammetric Analysis on six cadaver specimens.

In six cadaver specimens the mobility of the proximal fibula in relation to the tibia was investigated during plantar/dorsiflexion of the ankle, using Roentgen Stereophotogrammetric Analysis (RSA). The role of the ankle joint, and of the calcaneofibular and talofibular ligaments was also evaluated. The greatest movements were observed along the mediolateral and anterior-posterior axes, resulting in an anterolateral displacement of the fibula head during dorsiflexion and in a postero-medial displacement during plantarflexion. This study demonstrated a limited mobility of the proximal tibiofibular joint. Moreover, the ligament cutting and the presence of constraints in the ankle region did not show any effect on the fibular movement.

Analysis of Variance↗
PubMed1999

Reconstruction of extensive long-bone defects in sheep using porous hydroxyapatite sponges.

The capacity of hydroxyapatite (HA) implants to support large defect repair in weight-bearing long bones of large size animals was investigated. Diaphyseal resections 3.5 cm of the tibia were performed in five adult sheep. They were substituted with HA macroporous ceramic cylinders anatomically shaped, and an external fixator was assembled. The sheep were sacrificed at 20, 40, 60, 120, and 270 days after surgery, respectively. Histology and micro X-ray study of resected implants and adjacent tissues showed proper integration of ceramic with newly formed periosteal bone as early as 20 days after surgery. In one sheep, the external fixator was removed 5 months after surgery. The animal gained the ability to walk with no functional impairment until it was sacrificed 4 months later. At this time, extensive integration of ceramic with bone was detected radiographically and confirmed by a morphological study of the resected sample. Our data indicate that large defects in a weight-bearing long bone can be repaired to the extent necessary for full functional recovery in large animals. These data set the stage for further intervention on material properties as well as for preliminary attempts to use ceramic prostheses for reconstruction of large bone defects in humans.

Animals↗