Replacement Arthroplasty: Giannini S

Punzi L, Canesi B, Carrabba M, Cimmino MA, Frizziero L, Lapadula G, Arioli G, Chevallard M, Cozzi F, Cricelli C, Fioravanti A, Giannini S, Iannone F, Leardini G, Mannoni A, Meliconi R, Modena V, Molfetta L, Monteleone V, Nava T, Parente L, Paresce E, Patrignani P, Ramonda R, Salaffi F, Spadaro A, Marcolongo R. · Cattedra ed UOC di Reumatologia, Università di Padova, Padova. · Reumatismo. · Pubmed #15470525 links to  free full text

Abstract: The recommendations for the management of osteoarthritis (OA) of the knee firstly proposed by the EULAR in 2000, have been updated in 2003. One of the most important objectives of the expert charged to provide these recommendations was their dissemination. Thus, the information generated may be used by each individual country to produce their own set of management guidelines and algorithms for treatment in primary care. The Italian Society of Rheumatology (SIR) and the Italian League against Rheumatism (LIMAR) have organised a Consensus on the EULAR recommendations 2003 with the aim to analyse their acceptability and applicability according to our own experience and local situations in the Italy. The results of this Consensus have demonstrated that a large majority of the EULAR recommendations are endorsed by the Italian experts. Furthermore, the final document of the Italian Consensus clearly indicated the need that specialists involved in the management of knee OA strongly encourage the dissemination of the EULAR 2003 recommendations also in Italy.

Moroni A, Cadossi M, Bellenghi C, Romagnoli M, Bevoni R, Giannini S. · Bologna University, Rizzoli Orthopaedic Institute, Bologna, Istituti Ortopedici Rizzoli, Via G C Pupilli 1, 40136 Bologna, Italy. · Expert Rev Med Devices. · Pubmed #17280540 No free full text.

Abstract: Total hip resurfacing has long been conceptually attractive to both surgeons and patients. However, historically it has been plagued by limited durability and marked acetabular bone loss. The recent development of wear-resistant bearings, such as metal-on-metal, has led to renewed interest in hip resurfacing in the orthopedic community. Several resurfacing implants have been designed and positive results, particularly in young patients, have been reported. Although comparative studies of hip resurfacing and standard total hip replacement are still lacking, we believe that there is now evidence to demonstrate that this surgical concept deserves consideration, particularly when treating young patients with hip diseases.

Benedetti MG, Catani F, Bilotta TW, Marcacci M, Mariani E, Giannini S. · Movement Analysis Laboratory, Instituto Ortopedico Rizzoli, Via di Barbiano 1/10, 40 124, Bologna, Italy. · Clin Biomech (Bristol, Avon). · Pubmed #14527815 No free full text.

Abstract: 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.

Catani F, Biasca N, Ensini A, Leardini A, Bianchi L, Digennaro V, Giannini S. · Movement Analysis Laboratory, Department of Orthopaedic Surgery, Istituto Ortopedico Rizzoli, Via Di Barbiano 1/10, 40136 Bologna, Italy. · J Bone Joint Surg Am. · Pubmed #18381314 No free full text.

Abstract: BACKGROUND: Computer-navigated total knee arthroplasty is aimed at improving accuracy in the positioning of prosthetic components and realigning the lower limb. The optimal position and orientation of the bone resection planes are targeted by the navigation system, but, after these are obtained, additional manual surgical actions, which may considerably affect final component alignment, are necessary for implantation. The aim of this study was to measure the alignment deviation caused by standard impaction of the tibial and femoral components following bone resections with use of navigation control. METHODS: Ninety-one primary total knee arthroplasties were performed with an image-free knee navigation system. The alignment of the tibial and femoral bone resections was measured in three planes during surgery by the instrumented probe of the system. The alignment measure was repeated after final tibial and femoral component implantation with cement. The alignment deviations between the two measures were considered the positioning error associated with the final manual implantation of the components. RESULTS: The alignment deviations between the bone resections and the subsequent implant placement were >1 degrees in the frontal plane of the femur and in the frontal and sagittal planes of the tibia in 20%, 11%, and 33% of the patients, respectively. The deviations were >2 degrees in 4%, 3%, and 9% of the patients, respectively. Deviations as large as 3 degrees were found at the tibia in the sagittal plane (the posterior slope). CONCLUSIONS: Positioning of the femoral and tibial components in total knee arthroplasty, which mainly involves cementation and impaction of the final components, can introduce a considerable error in alignment, regardless of how accurately the resection planes are made. After computer-navigated total knee arthroplasty, it would be useful therefore to check the alignment of the prosthetic component carefully before the cement hardens.

Benedetti MG, Leardini A, Romagnoli M, Berti L, Catani F, Giannini S. · Movement Analysis Laboratory, Rizzoli Orthopedic Institute, University of Bologna, Bologna, Italy. · J Am Podiatr Med Assoc. · Pubmed #18202330 No free full text.

Abstract: BACKGROUND: Most clinical studies on total ankle replacement (TAR) report assessments based on traditional clinical scores or radiographic analysis. Only a few studies have used modern instrumentation for quantitative functional analysis during the execution of activities of daily living. The aim of this study was to use gait analysis to compare the functional performance of patients who underwent TAR versus a control population. METHODS: A retrospective analysis was performed of ten consecutive patients who had undergone meniscal-bearing TAR. Clinical and functional assessments were performed at a mean follow-up of 34 months with a modified Mazur scoring system and state-of-the-art gait analysis. RESULTS: Gait analysis assessment of TAR at medium-term follow-up showed satisfactory results for all patients, with adequate recovery of range of motion. Because the literature reports unsatisfying long-term results, it is important to evaluate these patients over a longer follow-up period. CONCLUSIONS: This study showed that TAR yields satisfactory, but not outstanding, general functional results at nearly 3 years' follow-up. These gait analysis results highlight the importance of integrating in vivo measurements with the standard clinical assessments of patients who underwent TAR while they perform activities of daily living. These results also emphasize the importance of evaluating the functional outcome of TAR over time.

Moroni A, Savarino L, Cadossi M, Baldini N, Giannini S. · VI Division, Istituti Ortopedici Rizzoli, Via di Barbiano 1/10, Bologna, Italy. · Clin Orthop Relat Res. · Pubmed #18196364 links to  free full text

Abstract: Modern metal-on-metal hip resurfacing was introduced as a bone-preserving method of joint reconstruction for young and active patients; however, the large diameter of the bearing surfaces is of concern for potential increased metal ion release. We hypothesized there were no differences in serum concentrations of chromium, cobalt, and molybdenum between patients who had metal-on-metal hip resurfacing (Group A; average head diameter, 48 mm; median followup, 24 months) and patients who had 28-mm metal-on-metal THA (Group B; median followup, 25 months). Serum concentrations also were compared with concentrations in healthy subjects. We identified no differences in ion levels between Groups A and B. A distinction was made according to gender. Women showed a higher chromium release in Group A whereas men had a higher cobalt release in Group B. Values obtained from Group A were higher than those of the control subjects. Our data suggest metal-on-metal bearings for THA should not be rejected because of concern regarding potential increased metal ion release; however, patients with elevated ion levels, even without loosening or toxicity, could be at higher risk and should be followed up periodically. Level of Evidence: Level III, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Belvedere C, Ensini A, Leardini A, Bianchi L, Catani F, Giannini S. · Movement Analysis Laboratory, Centro di Ricerca Codivilla-Putti, Istituti Ortopedici Rizzoli, Bologna, Italy. · Int J Med Robot. · Pubmed #17619241 No free full text.

Abstract: BACKGROUND: To improve the anatomy-based alignment of prosthetic components in total knee replacement, surgical navigation systems have recently been developed, based on anatomical reference frame definitions through landmark digitations and functional calibration. In this study, femoral and tibial resection plane alignments, obtained by conventional tecnique, were measured intraoperatively during total knee replacements by a navigation system to quantify potential errors in conventional bone preparation techniques. METHODS: Femoral and tibial resection plane alignments, obtained by conventional femoral intramedullary and tibial extramedullary cutting guides, were measured intraoperatively in 25 primary total knee replacements by a navigation system. This system enabled the surgeon to calculate, before definitive bone sawing, the final position and orientation of all resection planes. RESULTS: The measurements revealed unsatisfactory alignments in nearly all anatomical planes. Except for tibial varus/valgus, final plane orientations were considerably different from those targeted by the surgeon via the navigation system, respectively 7 degrees, 8 degrees and 10 degrees apart in varus-valgus and flexion-extension at the femur, and in flexion-extension at the tibia. CONCLUSION: Modern computer-aided surgery in total knee replacement, once relevant precision has been established in all femur and tibia anatomical planes, can in the future limit the current critical component misalignments.

Colangeli M, Donati D, Benedetti MG, Catani F, Gozzi E, Montanari E, Giannini S. · Bone Tumor Centre, Istituti Ortopedici Rizzoli, Bologna, Italy. · Int Orthop. · Pubmed #17393162 links to  free full text

Abstract: Total knee modular megaprosthesis or osteochondral allograft are used to preserve joint movement in bone tumours of the proximal tibia. The aim of this study was to compare two groups of patients with total knee modular megaprosthesis and osteochondral allograft through an objective analysis. Eighteen patients, ten treated with prosthesis (TKR group) and eight with osteochondral allografts (AL group), were included in the study. X-ray, muscular strength measurements, and studies of gait analysis including electromyography (EMG) were used to compare functional results of patients. In the TKR group a higher incidence of knee extension lag was found. While the TKR group had a prevalent knee stiff/hyperextension pattern with reduced rectus femoris activity, the AL group had a higher percentage of normal knee pattern. Knee extensor muscular strength was reduced in the TKR group. TKR functional performance during gait is in most cases abnormal, consistent with the weakness of the extensor apparatus and knee extension lag. Although a greater rate of normal walking was found in the AL group, problems related to a short patellar tendon, knee instability, and joint mismatching were considered to be responsible for abnormal knee kinematics. An allograft, when optimal reconstruction is performed, gives better functional results.

Ensini A, Catani F, Leardini A, Romagnoli M, Giannini S. · Department of Orthopaedic Surgery, University of Bologna, Italy. · Clin Orthop Relat Res. · Pubmed #17195810 No free full text.

Abstract: In this prospective, randomized, controlled study, we compared the performance of conventional and navigated total knee arthroplasties. Component alignment was measured in 60 patients operated on using navigation and in 60 patients operated on using the conventional technique. The groups then were divided into a subpopulation to measure alignments of the distal femoral cuts in the three anatomic planes, the proximal tibial cut in the frontal and sagittal planes, and the resulting lower limb mechanical axis in the frontal plane. Postoperative weightbearing long-view radiographs were evaluated as were clinical results using three standard questionnaires at 28 months followup. The intraoperative measurements (mean +/- standard deviation) at the resection planes showed navigated surgeries result in more accurate alignments than conventional surgeries for the femur: in the frontal plane, 0.1 degrees +/- 0.9 degrees and 0.7 degrees +/- 1.6 degrees valgus, respectively; in the sagittal plane, 1.1 degrees +/- 1.8 degrees and 2.8 degrees +/- 2.0 degrees flexion; and in the transversal plane, 0.1 degrees +/- 1.2 degrees and 0.9 degrees +/- 1.7 degrees internal rotation. The navigated technique also reduced the number of cases with final mechanical axes greater than 3 degrees from 20.0% to 1.7%. Postoperative radiographs showed better component alignment using navigation, particularly at the femur. However, clinical scoring systems showed this radiographic improvement did not necessarily result in a better clinical outcome at short-term followup.

Fantozzi S, Catani F, Ensini A, Leardini A, Giannini S. · Department of Electronics, Computer Science and Systems, Università di Bologna, Viale Risorgimento 2, 40136 Bologna, Italy. · J Orthop Res. · Pubmed #17019683 No free full text.

Abstract: Restoration of the physiological flexor/extensor mechanism at the knee in terms of appropriate muscular lever arms, proper required quadriceps force, and suitable patellofemoral compressive force, is fundamental for the success of total knee replacement. Therefore, measurements of anteroposterior translation of the femoral component over the tibial base-plate against joint flexion during daily living activities are essential for the assessment of the in vivo performance of current prosthesis designs. Patients treated with posterior stabilized and cruciate retaining prostheses with excellent clinical scores were evaluated during stair climbing, sitting and rising from a chair, and step up and down, using a three-dimensional pose reconstruction technique based on videofluoroscopy. The posterior stabilized patients experienced a fairly consistent and physiological rollback specific of each motor task, demonstrating proper function of the spine-cam mechanism. Rollback was somehow inconsistent among subjects in the cruciate retaining group, accompanied with a smaller range of knee flexion. In this group, more posterior locations of the condyles correlated significantly with higher clinical and functional scores. Articular surface conformity restores physiological rollback in the presence of a spine-cam mechanism, but not coherently in the presence of the posterior cruciate ligament.

Berti L, Benedetti MG, Ensini A, Catani F, Giannini S. · Movement Analysis Laboratory, Department of Orthopaedic Surgery, Istituti Ortopedici Rizzoli, Via di Barbiano 1/10, 40136 Bologna, Italy. · Clin Biomech (Bristol, Avon). · Pubmed #16516359 No free full text.

Abstract: BACKGROUND: Currently there is a limited understanding of the factors influencing range of motion by comparing patellar resurfacing vs non-resurfacing in total knee arthroplasty during activities of daily living. A recent meta-analysis of patellar replacement confirms better outcome with patella resurfacing; however, the result can be influenced by many other factors, such as: component design, surgeon experience, and technical aspects of the surgery. This study compares the biomechanics of the knee in patients after total knee arthroplasty with and without patellar resurfacing during stair climbing. METHODS: Forty-seven patients with total knee arthroplasty were assessed at the mean follow-up of 24 months. In all of them a posterior stabilised fixed bearing prosthesis (Optetrak PS, Exactech) was implanted. Twenty-six patients were treated without patellar resurfacing and 21 with patellar resurfacing. Clinical evaluations were performed using the International Knee Society and the Hospital for Special Surgery scores. Ten patients with patellar resurfacing and 10 patients without patellar resurfacing were also studied with motion analysis during stair climbing; 10 healthy subjects were studied for statistical comparison. FINDINGS: Clinical passive knee flexion, International Knee Society Function and Hospital for Special Surgery scores were significantly higher in the patellar resurfacing group. During stair climbing, active knee joint range of motion during the stance phase was greater in patients with patellar resurfacing. The maximum adduction moment was significantly higher in the group without patellar resurfacing. INTERPRETATION: Patients with patellar resurfacing demonstrated better clinical scores, and kinematic and kinetic data while ascending stairs.

Catani F, Fantozzi S, Ensini A, Leardini A, Moschella D, Giannini S. · Department of Orthopaedic Surgery, University of Bologna, Bologna, Italy. · J Orthop Res. · Pubmed #16514660 No free full text.

Abstract: The relation between prosthesis component kinematics and posterior slope of the tibial component in total knee arthroplasty is much debated. Three-dimensional kinematics of the replaced knee was obtained by video fluoroscopy in 23 knees treated by cruciate-retaining or cruciate-substituting arthroplasty. Relative position and orientation of the metal components were calculated in stair ascending, getting up from and sitting down on a chair, and single step up-and-down. Significant correlations were found between tibial component posterior slope and anteroposterior position of tibiofemoral lateral contact and between this slope and maximum knee flexion. These correlations were task and design specific. However, the average of the tibiofemoral contact positions over all three motor tasks was slightly posterior to the midline of the tibial base plate, reaching at most 84% of its anteroposterior dimension. Performing a posterior slope of the tibial cut does not put total knee arthroplasty with high conforming designs at higher risk of failure, even when large posterior inclinations need to be achieved.

Catani F, Ensini A, Leardini A, Bragonzoni L, Toksvig-Larsen S, Giannini S. · Movement Analysis Laboratory, Istituti Ortopedici Rizzoli, Bologna, Italy. · J Arthroplasty. · Pubmed #15902865 No free full text.

Abstract: The aim of this study was to investigate the migration pattern of the Lubinus SP II prosthesis stem. Migration at the stem-cement and at the bone-cement interface was assessed. Twenty-five patients were studied by radiostereometry during a period of 2 years. The migration of the head, of 2 points on the collar, of the stem tip, and also of the cement restrictor, was measured. The collar and the head were found stable at 2 years' follow-up, whereas an anterior migration occurred at the stem tip (median, 0.3 mm; 25th percentile, 0.04 mm; 75th percentile, 1.27 mm). Virtually no subsidence or axial rotation of the stems was observed. An anterior migration of the restrictor marker was also observed, compatible with a rigid sagittal plane rotation of the stem and of the cement mantle about the collar. Therefore, stem tip migration occurred at the bone-cement interface. Key words: total hip arthroplasty, anatomic stem, radiostereometry, subsidence, bone-cement interface.

Rizzo A, Catani F, Ensini A, Turriago MV, Giannini S. · Laboratorio Analisi del Movimento, Istituto Ortopedico Rizzoli, Bologna. · Chir Organi Mov. · Pubmed #15751590 No free full text.

Abstract: The authors report their experience in the implantation of 108 posterior-stabilized cemented total knee replacements, where in 43 cases the patella was not resurfaced (group 1) and in 65 in was resurfaced (group 2). The ability to perform daily activities, the subjective function of the patello-femoral joint and the index of patient satisfaction were evaluated by means of a telephone interview; furthermore, a clinical-radiographic evaluation was carried out in 50 cases. The results of the present study indicate the need of resurfacing the patella using a posterior-stabilized prosthetic design, based on the fact that more joint excursion, a low incidence of complications on the patello-femoral joint, and improved ability to perform daily activities were demonstrated.

Catani F, Leardini A, Ensini A, Cucca G, Bragonzoni L, Toksvig-Larsen S, Giannini S. · Istituti Ortopedici, Rizzoli, Bologna, Italy. · J Arthroplasty. · Pubmed #15343540 No free full text.

Abstract: Micromotion of the tibial component in 40 knee arthroplasties for gonarthrosis was studied using Roentgen stereophotogrammetric analysis. The stability of this component was assessed for 2 years' postoperatively. In all arthroplasties, an attempt was made to reconstruct the preoperative posterior slope. Posterior cruciate-retaining (CR) and posterior-stabilized (PS) components showed at 2 years a maximum total point motion of 0.6 +/- 0.4 mm and 0.7 +/- 0.5 mm, respectively. Whereas 92.5% of the implants were determined to be stable, 1 of the CR group and 2 of the PS group displayed migration between the first and the second year of at least 0.2 mm. A negative correlation between subsidence of the tibial component at 2 years of follow-up and the difference between preoperative and postoperative tibial slope was found. Consequently, we suggest that restoring the original posterior slope of the tibial plateau must be a goal of tibial component implantation.

Leardini A, O'Connor JJ, Catani F, Giannini S. · Movement Analysis Laboratory, Istituti Ortopedici Rizzoli, Via di Barbiano 1/10, 40136 Bologna, Italy. · Clin Orthop Relat Res. · Pubmed #15241142 No free full text.

Abstract: Our prior research has shown that currently available total ankle implants fail to restore physiologic ankle mobility. Most of the modern mobile-bearing designs that feature a flat tibial component and a talar component with anatomic curvature in the sagittal plane function nonphysiologically with the natural ligament apparatus. To establish a more natural relationship between the implanted components and the retained ankle ligaments, we have developed a new design. According to our prior research, we suggest that physiologic ankle mobility is reproduced best with a design featuring a spherical convex tibial component, a talar component with radius of curvature in the sagittal plane longer than that of the natural talus, and a fully conforming meniscal component. Our preliminary observations in trial implantation and in a few patients suggest that while reproducing physiologic ankle mobility, the new design is capable of maintaining complete congruence at the two articulating surfaces of the meniscal bearing over the entire motion arc, with the prospect of minimizing wear of this component.

Fantozzi S, Leardini A, Banks SA, Marcacci M, Giannini S, Catani F. · Movement Analysis Laboratory, Istituti Ortopedici Rizzoli, Via di Barbiano 1/10, 40136, Bologna, Italy. · Knee Surg Sports Traumatol Arthrosc. · Pubmed #15024562 No free full text.

Abstract: 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.

Benedetti MG, Catani F, Donati D, Simoncini L, Giannini S. · Istituti Ortopedici Rizzoli, Bologna, Italy. · J Bone Joint Surg Am. · Pubmed #11097453 No free full text.

Abstract: 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.

Verdini F, Leo T, Fioretti S, Benedetti MG, Catani F, Giannini S. · Dipartimento di Elettronica ed Automatica, University of Ancona, 60131, Ancona, Italy. · Clin Biomech (Bristol, Avon). · Pubmed #10936433 No free full text.

Abstract: 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.

Moroni A, Faldini C, Piras F, Giannini S. · Ninth Department of Orthopaedic Surgery, Rizzoli Orthopaedic Institute, Bologna University, Italy. · Ann Chir Gynaecol. · Pubmed #10905677 No free full text.

Abstract: BACKGROUND AND AIMS: Intraoperative femoral fractures are a serious complication of total hip replacement. The purpose of this study was to evaluate the risk factors of intraoperative femoral fractures in a retrospective analysis of a series of 3,566 total hip replacements. MATERIALS AND METHODS: The patients were divided into two groups, A and B. Group A patients had no intraoperative femoral fractures and Group B patients had intraoperative femoral fractures. In Group A there were 3,483 patients (97.7%) and in Group B, 83 (2.3%). The following potential risk factors were evaluated: sex, age, diagnosis, previous surgery at the homolateral hip, surgical approach, fixation type of the femoral component, prosthesis type, surgical stage during which the fracture occurred, and the lead operating surgeon. RESULTS: The fracture incidence was higher in females (p < 0.005) in uncemented femoral components (p = 0.005), in patients who had previous surgery at the homolateral hip (p < 0.005), and in revision surgery (p < 0.005). CONCLUSION: The analysis of intraoperative femoral fracture risk factors should allow the surgeon to improve the surgical performance and therefore reduce the incidence of this severe intraoperative complication.

Moroni A, Rocca M, Faldini C, Stea S, Giardino R, Giannini S. · Ninth Department of Orthopaedic Surgery, Rizzoli Orthopaedic Institute, Bologna University, Italy. · Ann Chir Gynaecol. · Pubmed #10532562 No free full text.

Abstract: The purpose of this paper is to evaluate in an animal model the long term results obtained with a prosthetic stem fully coated with hydroxyapatite. The cup was manufactured in polyethylene and was cemented. Six arthroplasties were performed in six sheep. After twelve months, the animals were euthanized and the femurs were harvested and processed for undecalcified sectioning. Twelve cross sections were cut perpendicularly to the longitudinal stem axis. Sections one to five corresponded to the area of the stem which, at the time of surgery, had a full initial contact between the bone and the prosthesis; sections six to ten corresponded to the area of the stem which, at the time of surgery, had a gap from 0 to 2 mm between the bone and the prosthesis; sections eleven and twelve had an initial gap larger than 2 mm. At one year after implantation, in the sections one to five, morphological analyses showed extensive direct contact between the bone and the hydroxyapatite coating. Bone prosthesis contact was lower in the sections six to ten. No contact was seen in sections eleven and twelve. Comparing bone to prosthesis contact of each subsequent section, from proximal to distal, the difference becomes significant with section five compared to section six (p < 0.00005). No detachment of the hydroxyapatite coating from the metallic substrate was observed in any section. In conclusion, this study shows that a conic shaped femoral stem, fully coated with hydroxyapatite gives very good histological and histomorphometric results at one year. Prosthesis osteointegration showed to be influenced by the initial bone to prosthesis contact. No direct bone to prosthesis contact was achieved if the initial bone to prosthesis gap was larger than 2 mm.

Leardini A, O'Connor JJ, Catani F, Giannini S. · Movement Analysis Laboratory, Istituto Ortopedico Rizzoli, Bologna, Italy. · J Biomech. · Pubmed #10332622 No free full text.

Abstract: 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.