INTRODUCTION

Osteochondral defects are still a challenge for the orthopaedic surgeon, since most of the current surgical techniques lead to fibrocartilage formation and poor subchondral regeneration, often associated to joint stiffness and/or pain.

Thinking of the ideal osteochondral graft from both the surgical an commercial point of view, it should be an off-the-shelf product; this is the research direction and the explanation for the new biomaterials recently proposed to repair osteochondral defect inducing an “in situ” cartilage regeneration starting from the time of the implantation into the defect site.

For the clinical pilot study we performed, a newly developed nanostructured biomimetic scaffold was used to treat chondral and osteochondral lesions of the knee; its safety and manageability, as much as the surgical procedure reproducibility and the clinical outcome, were evaluated in order to test its intrinsic potential without any cells colture aid.

INTRODUCTION

The menisci play a fundamental biomechanical role in the knee and also help in the maintaining of the articular homeostasis; thus, either a lesion or the complete absence of the menisci can invalidate the physiological function of the knee causing important damages, even at long term. Unfortunately, meniscal tears are often found during the ordinary orthopaedic practice while the regenerative potential of this kind of tissue is very low and limited to its peripheral-vascularized part; this is why the majority of these common arthroscopic findings are not reparable and often the surgeon is almost forced to perform a partial, subtotal or even total meniscectomy, regardless of the well-known consequences of this kind of surgery.

Traumatic anterior shoulder dislocation and sub-luxation are common injuries. But few studies have compared arthroscopic and open stabilization of the shoulder at long-term follow up. The purpose of our study is to show whether an arthroscopic approach to repair Bankart lesion can obtain the same results at long follow up as an open procedure. We analyzed 110 non-randomized consecutive shoulders in 110 patients who underwent a surgical repair of recurrent anterior shoulder instability between 1990 and 1999. Eighty-two patients were available at long term follow up (74,5% retrieval rate). In particular, 49 patients (59.8%) (group A) were treated with arthroscopic transglenoid suture (modified Caspari) between 1990 and 1995 (mean 15,7 year FU), whereas, 33 patients (40.2%) (group B) were treated with open repair between 1995 and 1999 (mean 12,7 year FU). We evaluated the patients in terms of failure rates, Rowe and UCLA scores. The failure cases in the forty-nine patients treated with arthroscopic suture were 13, six dislocations and seven subluxations. The group A had also a Rowe score: function 24.2+8.2, stability 42.4+13.9, range of movement 18.6+3.8, total score 85.0+22.46. The UCLA score was: pain 8.8+1.7, function 8.6+2.1, muscle power 9.2+1.6, total score 26.4+4.8. Of the thirty-three patients treated with open repair, three had at least one post-op dislocations and four felt sometimes subluxations. The Rowe score in group B was: function 23.6+9.7, stability 41.2+14.9, range of movement 18.3+3.9, total score 83.2+24.4. Moreover the UCLA score was: pain 8.8+1.9, function 8.8+1.9, muscle power 9.2+1.2, total score 26.9+4.2. We showed that both techniques were fairly good in treatment of shoulder instability. In our series no significant difference was observed in redislocation rate and in Rowe and UCLA scores between the two groups. The recurrence rate (subluxations and dislocations) was high in both groups: the arthroscopic group had 26.5% and the open one had 21.2%. Our recurrence rate following open repair was higher than in many studies, while the rate after arthroscopic transglenoid procedure was almost equivalent. We hypothesize that one of the reasons for these higher recurrence rates may be the long term follow up. Another cause could be our decision to include subluxation as a failure value, even if there is no agreement about. In fact we believe it to be an important disability factor in sport as in life activities. After surgery, most of the patients returned to their preinjuried activities. But at long term follow up almost all patients have stopped high level sport activity. Moreover, at this long term follow up, some patients told us a feeling of muscle weakness in the last years. In conclusion patients had good impressions about their shoulders thanks to surgery, but also because of lower functional demand.

Introduction: Several in vitro and in vivo studies have found correspondence between transepicondylar axis (TEA) and mean helical axis (MHA) in healthy subjects. In addition some studies suggest that the use of MHA for rotational alignment of femoral implant may be more accurate than TEA. Ostheoarthritis (OA) may modify limb alignment and flexion axis, introducing a bias during kinematic acquisition. An in-vivo study comparing normal and osteoarthritic knees using MHA is still lacking. The purposes of this study were: to understand whether arthritis affects somehow the functional axis evaluation and then to assess whether the MHA could be considered as reference flexion axis also for osteoarthritic knees; starting from hypothesis that there is a correspondence between TEA and MHA, to evaluate whether in pathologic subjects there still is the same correspondence.

Material and Methods: We included a group of 15 OA patients undergoing TKA and, as control group, 60 patients that underwent ACL reconstruction, since in vivo studies reported small differences in kinematics between ACL reconstructed and uninjured limbs. With a surgical navigation system we recorded intraoperative kinematic data of different passive ranges of motion (PROM) and calculated the MHA applying a least square approach to the set of finite helical axes (FHA) obtained in three different ranges of motion (0°–120°; 35°–80°; 35°–120°). We compared the difference in orientation of MHA in the three ranges with respect to the TEA on frontal (XZ) and axial (XY) planes. The correlation of preoperative limb deformity with MHA-TEA angle was also performed.

Results: The results of difference of MHA-TEA angle between the OA and ACL groups for all the three ranges of flexion and in XZ and XY views showed no statistical difference (p=0.5188; p=0.7147 respectively). No statistical difference was found also about MHA-TEA angle between the three ranges in frontal and axial views (ANOVA p=0.6373; p=0.4183 respectively). There was no difference between the flexion and extension movements in the three ranges. We also found that correlation between limb alignment and MHA-TEA angle showed good correlation (r> 0.54, p< 0.001) in frontal view and fair correlation (r< 0.37, p< 0.05) in axial view for all ranges.

Conclusions: Our work has demonstrated that pathologic knees shows no differences in MHA orientation compared to nearly healthy subjects, moreover there is the same correspondence between TEA and MHA both in XZ and XY plane. We also found that preoperative limb alignment does not correlate with MHA-TEA angle. results are in agreement to studies on healthy subjects. Therefore the MHA may be considered a reliable reference for determining femoral flexion axis and a useful tool in the determination of femoral implant positioning on axial plane, even in surgical setup on osteoarthritic patients.

We performed a clinical, instrumental and radiographic study on a highly homogeneous series of 100 consecutive patients with unilateral ACL lesion at 7 years of minimum follow up, alternatively assigned to a single bundle reconstruction using patellar tendon (PT) or to a double bundle reconstruction using hamstrings (DB). Mean Tegner score was 4,8 for PT and 6,5 for DB (p=0,0005). Time for sport resumption was 6,6 months for PT and 3,8 months for DB (p=0,0052). There were no significative differences between the two groups regarding range of motion and functional subjective self-evaluation. Mean anterior displacement at instrumental evaluation performed with KT2000 showed no significative differences between the two groups. Objective clinical evaluation with IKDC was superior for DB group (A=86,5%; B=13,5%) respect to PT group (A=18,7%; B=75%; C=6,3%) (p< 0,0001). We found no differences regarding anterior knee pain between and Ahlback radiographic score the two groups and we have observed no recurrence of instability after surgical treatment. Double bundle ACL reconstruction with hamstrings has showed higher results respect to single bundle ACL reconstruction with patellar tendon in terms of Tegner score, IKDC, time for sport resumption.

We performed a retrospective clinical and radiographic evaluation of 100 cases operated in our institute between February 1996 and March 2003 with a mean follow-up of 60 months to assess the efficiency of UKR performed with a new minimally invasive technique. The aim of this study is to correlate the clinical outcome of the patients with the pre- and post-op alignment, and with implant positioning on coronal and sagittal plane.

100 patients (23 ♂, 64 ♀) underwent cemented UKR (De Puy Preservation Uni with all poly tibial component), both for arthritis and osteonecrosis. At the pre-op clinical and radiographic evaluation, 82 patients presented a varus deformity, 5 patients a valgus deformity. The Hospital for Special Surgery Score (HSS) was used to determine the subjective and objective clinical status of the patients before and after the intervention.

Pre-op antero-posterior (AP) x-rays of the knee were executed to establish the femoro-tibial angle (FTA) and the angle between the affected tibial plateau and the tibial anatomical axis (PTA), while latero-lateral (LL) x-rays were performed to determine the posterior tibial slope (PS). To analyze ligamentous balancing, x-rays were performed both in supine and in plain weight bearing stance. Post-op, we performed supine AP e LL X-rays and at a mean follow-up of sixty months (12–84 months) we performed AP and LL plain weight bearing x-rays.

We considered a knee with FTA > 175° as varus knee, 170°< FTA< 175° as normal knee and an FTA < 170° as valgus knee. Moreover, we assumed a TPA > 90° for valgus knee and a TPA< 90° for varus knee.

According with HSS scoring system, at a mean follow-up of 60 months, 63 (76%) cases were excellent (100-85 points), 15 (18%) cases were good (84-70 points), 5 (6%) bad results (< 60 points). Our results demonstrate that patients with a pre-operative varus alignment of 7 degrees are slightly more likely to be selected for UKR. In our series, patients with an excellent clinical result presented pre-operatively a mean varus deformity of 7,9°. According to literature, we demonstrated that a small amount of undercorrection with a residual varus deformity of 3–5° is the goal to be reached in order to avoid both rapid degeneration of the non-replaced compartment as well as the premature loosening of the replaced compartment. We performed a mean axial correction of 5,1° leaving a mean axial varus deformity of 2,8° in the excellent group. In our series the group with excellent results also showed a post-operative PTS of 7,1°, while mean pre-operative PTS was 6,6°. Moreover, the further our radiographic findings were from the optimal position suggested, the worst were the results : a decrease was evident comparing excellent group with good group and this was even more marked comparing excellent group with bad results group.

Introduction: The hip joint is usually considered a ball-in-socket. However, there have been few studies evaluating normal hip kinematics and the contribution coming from soft tissues. Capsular laxity is at the basis of injury to the acetabular labrum (most common pathological lesion seen during hip arthroscopy). The objectives of this study were to (1) assess hip kinematics with all the soft tissues intact using a surgical navigation system, (2) assess the relative contributions of the soft tissues to hip stability and (3) assess the relative contributions of periarticular soft tissues to hip range of motion.

Materials and Methods: We used 4 normal hemicorpse specimens for a total of 8 hips. A navigation system (KLEE, Orthokey) was used to acquire the kinematic data. The anatomical reference system was identified through the palpation of landmarks: (1) anterior superior iliac spines (ASIS) and (2) pelvic tubercles for the pelvis, (3) femoral head center and (4) epicondyles for femur. There were 12 passive kinematic tests repeated 3 times in 3 different limb conditions (‘intact’, ‘no-skin-muscle’, ‘labral tear’) to explore the whole kinematic range. We analysed the differences in flexion/extension, abduction/adduction, internal/external rotation ranges (Wilcoxon’s Signed Ranks Test).

Results: The kinematic analysis applied on the limbs highlighted the following range of motion: (1) the F/E was 115.7 ± 2.4° (12.9 ± 1.0° in extension/101.7 ± 3.0° in flexion) in ‘intact’ limb, 139.2 ± 10.8° (14.7 ± 2.7° in extension/120.7 ± 8.6° in flexion) in ‘no-skin no-muscle’ condition, and 174.3 ± 34.1° (25.3 ± 0.5° in extension/147.4 ± 35.4° in flexion) in ‘capsule cut’ condition; all the ranges were statistically different (p < 0.05); (2) the A/A was 44.5 ± 13.7° (35.4 ± 1.5° in abduction/10.1 ± 13.4° in adduction) in ‘intact’ limb, 59.2 ± 1.8° (38.5 ± 3.2° in abduction/21.7 ± 0.7° in adduction) in ‘no-skin no-muscle’ condition, and 82.0 ± 4.6° (57.4 ± 2.5° in abduction/25.6 ± 6.8° in adduction) in ‘capsule cut’ condition; all the ranges were statistically different (p < 0.05); (3) the IR/ER was 52.2 ± 10.5° (32.0 ± 11.9° in IR/21.5 ± 1.0° in ER) in ‘intact’ limb, 59.2 ± 1.8° (36.1 ± 14.1° in IR/26.5 ± 1.2° in ER) in ‘no-skin no-muscle’ condition, and 116.4 ± 54.4° (58.2 ± 16.1° in IR/55.6 ± 36.3° in ER) in the ‘capsule cut’ condition; all the ranges were statistically different (p < 0.05), except the ranges of ‘intact’ condition and ‘no-skin no-muscles’ one (p = 0.37).

Discussion: The study of the 3 different conditions highlighted the critical role of the soft tissues in hip stability and kinematics; the soft tissues do provide stability mainly in limiting hip range of motion. This study’s findings are a preliminary contribution in the understanding of the contribution of periarticular muscles, joint capsule and ligaments to hip kinematics.

Introduction: The Collagen Meniscus Implant (CMI) has been shown to be effective for the replacement of lost medial meniscus tissue; however, no such device has been available for treatment of similar injuries to the lateral meniscus. Loss of the lateral meniscus results in a rapidly increased rate of knee degeneration compared to similar medial injuries. The purpose of this study was to determine if a CMI developed for use in treatment of lateral meniscus deficiencies is as safe and effective as has been reported for the medial CMI.

Methods: Prospectively, 60 patients (12–65 years of age) were enrolled at 7 sites between March 2006 and October 2007. Patients had irreparable lateral meniscus tears requiring partial meniscectomy. The knee had to be ligamentously stable and in neutral alignment and with no untreated Grade IV cartilage damage. Patients gave informed consent and agreed to comply with postoperative assessments and standardized rehabilitation. The surgical technique involved insertion of the dry implant into the lateral compartment of the knee joint. Fixation of the implant to the host meniscus rim was accomplished with either an all-inside suture technique or a hybrid all-inside/inside-out technique. Clinical evaluations and patient self-assessments were conducted preoperatively and at defined intervals through 2 years postoperatively. Procedure specific intraoperative parameters, radiographic evaluations, and adverse events were documented. Data collection was monitored by a third party according to GCP regulations.

Results: 49 patients received a lateral CMI. Currently, 24 patients have 1-year follow-up and 13 patients have been followed approximately 2 years; the mean follow-up is 22 months. Follow-up included assessments of changes in Lysholm, pain, Tegner and patient satisfaction. All patients showed clinical improvement from the preoperative to the 1 year postoperative time points. Four patients experienced adverse events which required an additional arthroscopic procedure between 4 and 16 months and included removal of implant remnants, synovectomy and debridement.

Conclusions: These preliminary results appear to suggest that implantation of lateral CMI leads to improved clinical outcomes in pain, function, self-assessment and activity levels. Frequency and type of adverse events are comparable to those for suture repair reported in the literature. Based on results reported for the medical CMI, we anticipate that these lateral CMI patients will have improved long-term results compared to partial lateral meniscectomy.

Arthroscopic selective resurfacing of the knee may be considered a treatment option for selected patients with focal articular damage.

From more than 2 years in IX Division of Rizzoli Orthopaedics Institute(Bologna- Italy) we use, in selected cases with only one articular compartment damaged, an innovative resurfacing prosthesis.

We mad a new design of focal resurfacing (MAIOR) that is possible to implant with arthroscopic technique and that realize both mini-invasive and mini-traumatic surgery.

The fixation method of the MAIOR allows higher osteointegration by biomaterials and hydrossiapatite of new generation that permit a press-fit fixation of the implant.

The new philosophy of this implant consist of early focal treatment with low compromise of bone. Many surgeons, in case of focal articular damage, prefer to attend to made an unique definitive surgical operation when the degenerative changes are more severe.

This new implant permit to substitute, also in arthroscopic technique, only the articular damage and to avoid to attend a more important and diffuse articualr damage.

It is an uncemented, focal resurfacing prosthesis that requires minimal bone sacrifice and utilizes a minimal invasive surgical (MIS) approach with or without arthroscopic assistance.

In a prospective and consecutive study, 78 patients were followed up at least for 12 months. Subjective pain and joint function were assessed using Visual analogue scale (VAS) and Knee society scores respectively. The preliminary results are interesting and encouraging with subjective evaluation equal to 85% of normal knee.

Significant reduction of pain and improvement in joint function was observed. Although, long term study will determine the real performance of the prosthesis, trend seems to be positive.

Introduction: Anterior Cruciate Ligament (ACL) is primary constrain to anterior displacement of tibia with respect to the femur and secondary to internal/external (IE) and varus/valgus (VV) rotations; an ACL reconstruction should thus control not only AP but also IE and VV laxities. For this reasons, more attention has given to residual rotational instability. This study aims to verify if those subjects with high of pre-op knee laxities has also high post-op laxity after an ACL reconstruction.

Material and Methods: The study includes 115 patients, that underwent ACL reconstructions between January 2005 and September 2007. Patients with associated severe ligaments tears or severe chondral defects were excluded. The joint passive kinematics was intra-operatively assessed using the BLU-IGS system (Orthokey, Delaware). We evaluated, before and after the reconstruction, the manual maximum IE rotation at 30° and 90° of flexion, VV rotation at 0° and 30° of flexion and AP displacement at 30° and 90° of flexion. We used the k-means algorithm applied to pre-op values to create two groups among the patients: the GROUP H, with higher pre-op laxity and the GROUP L, with lower pre-op laxity. The pre-op groups were compared for each test using independent Student’s t-test (p=0.01) in order to assess their difference. Student’s t-test (p=0.01) was performed on the corresponding post-op values in order to verify if the difference between H and L was maintained after the reconstruction.

Results: Mean pre-op VV at 0° was 7.1±0.9° for group H and 4.7±0.8° for group L (p< 0.01), post-op was 3.2±0.8° for group H and 2.5±0.8° for group L (p< 0.01). Mean pre-op VV at 30° was 6.2±1.5° for group H and 3.4±0.7° for group L (p< 0.01), post-op was 3.4±1.3° for group H and 2.2± 0.9° for group L (p< 0.01). Mean pre-op IE at 30° was 28.3±3.5° for group H and 19.2±3.1° for group L (p< 0.01), post-op was 21.5±3.8° for group H and 14.7±3.7° for group L (p< 0.01). Mean pre-op IE at 90° was 31.3±2.8° for group H and 22.4±3.5° for group L (p< 0.01), post-op was 22.3±4.0° for group H and 17.0±4.4° for group L (p< 0.01). Mean pre-op AP at 30° was 14.5±2.1mm for group H and 8.9±1.6mm for group L (p< 0.01), post-op was 6.2±1.6mm for group H and 4.2±1.6mm for group L (p< 0.01). Mean pre-op AP at 90° was 11.2±1.7mm for group H and 6.7±1.4mm for group L (p< 0.01), post-op was 5.4±1.8mm for group H and 3.4±1.3mm for group L (p< 0.01).

Discussion: The comparison between group H and group L showed that those patients with higher pre-op laxity had maintained higher post-op values mainly for all the tests. This finding is probably correlated to the possible presence of different tears affecting soft structures of the joint and to the proper and specific anatomy of each patient.

Information on knee kinematics during surgery is currently lacking. The aim of this study is to describe intra-operative kinematics evaluations during uni-compartmental knee arthroplasty (UKA) and total knee arthroplasty (TKA) by mean of a navigation system. Anatomical and kinematic data were acquired by Kin-Nav navigation system and analysed by a dedicated elaboration software developed at our laboratory. The study was conducted on 20 patients: 10 patients undergoing mini-invasive UKA and 10 patients undergoing posterior-substituting-rotating-platform TKA. In both group of patients the surgeon performed passive knee flexion immediately before and immediately after the prosthetic implant. Pattern and amount of internal/external tibial rotation in function of flexion were computed and significant changes between before and after implant were evaluated adopting Student’s t-test (significant level p=0.05).

UKA implant did not significantly change the pattern of internal/external tibial rotation, nor the total magnitude of tibial rotation (15.75°±7.27°) during range of flexion (10°–110°), compared to pre-operative values (17.87°±7.34°, p=0.25). Magnitude of tibial rotation in TKA group before surgery (8.00°±3.67°) was significantly less compared to UKA patients and did not changed significantly after implant (5.96°±4.88°, p=0.09). Pattern of rotation before and after TKA implant were different between each other and between pattern in UKA patients both before and after implant.

Intra-operative evaluations on tibial rotation during knee flexion confirmed some assumptions on knee implants from post-operative methods and suggest a more extensive use of surgical navigation systems for kinematic studies.

Total knee arthroplasty (TKA) is actually a satisfactory technique to reduce pain and enhance mobility in osteoartritic pathologies (OA) of the knee. However, life of the implant is strictly dependent on restoration of correct knee kinematics, as alteration of motion pattern could led to abnormal wear in prosthetic components and also damage soft tissues. The aim of our study was to evaluate new kinematic tests to be performed during surgery in order to improve the standard intra-operative evaluation of the outcome on the individual case. We used Kin-Nav navigation system to acquire anatomic and kinematic data, which were analysed by a dedicated elaboration software developed at our laboratory. Ten patients undergoing rotating platform cruciate substituting TKA were considered for this study. Immediately before the implant and immediately after component positioning, the surgeon performed 3 complete knee flexion imposing internal tibial rotation (IPROM) and 3 complete knee flexion imposing external tibial rotation (EPROM). Tibial rotation during IPROM and EPROM tests was plotted in function of flexion (in the range 10°–110°). Repeatability of IPROM and EPROM was tested by calculating ICC (Intra-class Correlation Coefficient) between 3 repeated curves. Distance between IPROM curve and EPROM curve was computed at various degree of flexion. Maximum distance obtained during all range of flexion before and after the implant were compared by Student’s t-test (significant level p=0.05).

ICC for repeated motions were 0.99 for IPROM and 0.98 for EPROM. Maximum distance between tibial rotation in IPROM and EPROM was 27.82±6.98 before implant and significantly increased (p=0.001) to 40.09±6.92 after TKA. In one case we observed that the value remained similar before and after implant (from 33.11 to 33.98) while in one case we observed very large increase of rotation (from 30.56 to 50.01).

The proposed kinematic tests were able to quantify the increase of tibial rotation after TKA implant. Future development of the study are encouraging and will include a larger sample and reflections on individual findings.

Aims: This work describes a new intraoperative computer-assisted method for the evaluation of joint kinematics in both total (TKA) and uni-compartmental (UKA) knee arthroplasty. We report schematically the protocol and the preliminary in-vivo results we obtained on 11 patients (9 UKA – 2 TKA).

Methods: The system consists of an optoelectronic localizer, 2 reference arrays and a dedicated acquisition software, that permits the real-time control of limb position and allows the acquisition of joint motions. After a first phase of registration (anatomical landmarks identification) the surgeon executes, both before and after the reconstruction, a series of passive tests: range of motion (PROM) evaluation, varus-valgus (VV) stress at 0°, and VV at 30°. Furthermore the surgeon can acquire also anatomical surfaces (tibial plateaus, femoral condyles, prosthetic components, etc.). The 3D kinematic evaluations and anatomical data are recorded before and after the joint reconstruction. This new methodology has been used during 11 interventions fulfilled at our institute. We compare the PROM results with literature, and we also analyzed the interoperator repeatability in the execution of the tests (3 repetitions performed by a senior surgeon).

Results: The kinematic analysis of the PROM showed that there were no significant differences between per-operative and post-operative in all UKA cases. In the 2 TKR cases internal-external (IE) rotations appeared reduced after the implant, but further data are necessary to have a statistical evidence. The extension was improved both in UKA and TKA. The VV laxity at 0 ° was significantly reduced (p < 0.001), while at 30 ° stayed constant (p = 0.010). In all the TKR cases the evaluation of contact areas between femoral and tibial components showed normal pattern, and in UKA the contacts remain inside the prosthesis areas. Measured kinematic parameters (knee rotations, screw-home mechanism and alignment) were comparable with literature and manual estimation at surgical time.

Conclusions: The proposed protocol optimizes surgical times and minimizes invasiveness. The preliminary results showed that the system is able to quantify new kinematic parameters during intraoperative evaluations, provides data about alignments, gaps, stability and 3D motions of the individual knee and therefore can allow an accurate and real-time estimation of the passive knee function. Moreover the new 3D anatomical and kinematic data can improve the biomechanical understanding of the pathological and prosthetic knees.

Aims: In Revision Total Knee Arthroplasty (RTKA), bone deficiencies and lack of anatomical references make it difficult to understand the normal knee kinematic and adequately plan the intervention. To our knowledge there are no data about computer assisted navigation system specifically developed for RTKA in the literature and existing navigated techniques for RTKA use navigation systems developed for primary TKA. A new computer assisted technique for RTKA is presented.

Methods: This technique is based on the use of a navigation system, RTKANav consisting of an optical localizer, a dedicated software and some navigated tools specifically done for RTKA. The system doesn’t use medical images, and patient anatomy model is represented with dots and lines corresponding to acquired landmarks, providing the surgeon with the main references for the intervention monitored in real-time. During the most critical steps of the intervention (soft tissue balancing and the consequent choice of implant size, and joint line height restoration), the system provide the surgeon with graphical and numerical tools to improve the surgical outcome. Several criteria to set each degree of freedom of prosthetic components are considered and compared, and even if some required landmarks can not be identified, the system is always able suggest an intervention plan. The surgeon is provided with tools to analyze and modify the proposed plan, and to reproduce it on the patient.

Results: Till now the presented technique was used on five patients by an expert surgeon. Qualitative results, collected after the intervention through a questionnaire on surgeon feelings, in order to assess the functionality, user friendliness and the data visualization criteria implemented were very satisfying. System reliability was assessed intraoperatively analyzing joint line height, limb alignment and knee stability using trial components: based on his experience, the surgeon checked some acceptable components combination and compared the corresponding outcome with the one provided by the implant planned by the system. In three out five cases the suggested implant was considered the best by the surgeon, while in one case he decided to change the tibial insert of one size because of knee instability and in another case he changed the tibial component of one size because the planned one was too small. Final limb alignment evaluated with postoperative x-rays, was satisfactory in all cases.

Conclusions: Presented navigation system showed early promising results providing the surgeon with intraoperative quantitative and qualitative information on the main surgical parameters, useful to achieve a satisfactory prosthesis implant. Moreover this system use anatomical patient specific landmarks acquired after prosthesys removal, while navigation systems developed for primary TKA use both reference taken from preoperative x-rays and anatomical references acquired on metal component to be removed. Therefore in this case the operation planning is based on rough anatomical landmarks that do not reflect patients original anatomy.

Purpose: Ultrastructural analysis of PT graft for ACL single bundle reconstruction.

Materials and methods: Arthroscopical biopsies for new meniscal lesions at 6-12-24mm-5-10 ys. All cases with IKDC normal/nearly normal and KT2000 excellent/good.

Samples prepared with Karnowsky fixing and urani-lacetate solution. Fibril diameter and transversal area measured by LEICA QUIN in 5 cuts randomly selected for each sample.

Results: 6 months biopsy showed severe P.T. modifications, with a decrease of larger fibrils, substituted with smaller one with plenty of extra cellular matrix. Oxitalan fibers, macrophagic cells and tenocytes were observed. At 12 months compact fascicles of small fibrils (50–60 nm) divided the larger one, similar to a normal tendon. At 24 months graft modifications were increased with wide compact fasciclesvariously oriented. At 5 and 10 years the modifications were similar to those observed at 2 years, with the graft not completely transformed in native ACL structure.

Discussion: The results showed that PT graft used for ACL single bundle reconstruction certainly undergoes a neoligamentization process up to two years. At longer follow-up the foresaw complete remodelling in a normal ACL was not observed. Heterogeneous fibrils presence suggests incomplete ligamentization or its impossible complete realization in single bundle ACL reconstructions.

Purpose: Functional, radiological and instrumental comparison between ACL reconstruction with Single Bundle plus lateral augmentation (SB) versus Double Bundle technique (DB).

Materials and methods: Random choice of 70 patients operated by the same equipe for ACL reconstruction with autologous hamstrings, 35 with SB+lateral augmentation and 35 with DB technique.

Investigation based on: Sport activity recover; IKDC; KT2000; isokinetical tests; muscular throphysm recover; Tegner and Lyshom score; Activity Rating Scale (ARS); Psychovitality Questionnaire; radio graphical evaluation in AP, LL and Rosemberg.

Results: IKDC results superior for DB group, with no bad results and superposable ROM for both groups. Sport activity recover in 100% patients of DB group, with reduced time respect to SB group. Excellent and superposable results for both groups at KT2000. Better muscular throphysm and isocinetic tests results for DB group. Ahlback score same to pre-op in both groups. ARS and Psychovitality questionnaire results better for DB group.

Discussion: Both surgical techniques guarantee excellent results.

DB technique allows a faster sport activity and muscular throphysm recover and better results in the isoci-netical tests.

The kinematic effect of tunnel orientation and position, during ACL reconstruction, has been only recently related to the control of rotational instability.

This paper presents a detailed computer-assisted in vitro evaluation of two different femoral tunnel orientations with the same tunnel position, at 10.30 ‘o clock, during the intervention of ACL reconstruction with double bundle technique. Results highlighted better kinematic performances of the horizontal tunnel, with respect to the vertical one, in controlling antero-posterior (AP) laxities at 30°, and internal-external (IE) laxities.

Elongations of anterior and posterior bundles of reconstructed ACL, for both reconstruction, decreased during PROM respectively by 20% and 40%. Total length of the graft varied during PROM, mainly due to graft elongation during tests, graft length on horizontal tunnel varied from 237 to 213mm while graft length on vertical tunnel varied from 257 to 233mm. Kinematic tests showed a better performance of horizontal tunnel in the control of IE rotations at 30° and 90° and of the Lachman test with respect to the vertical one. Stability was restored with both reconstructions.

A computer assisted technique for TKA Revision is presented. It is based on the use of a navigation system, RTKANav consisting of anl optical localizer, a dedicated software specifically done for TKA revision and some navigated tools developed for this application.

The system doesn’t use any patient model derived from medical images, but on the system interface patient anatomy model is represented with dots and lines corresponding to acquired landmarks and data derived from them. These data describe the main anatomical features and provide the surgeon with the main references for the intervention; angles between the mechanical axes can be controlled and monitored at any time.

Even if during acquisition phase some specific points can not be identified, since for each prosthetic component several criteria to set each degree of freedom are considered and compared, the system is always able suggest an intervention plan.

The system provides the surgeon with tools to analyse and modify the proposed plan, and to reproduce it on the patient.

Navigated technique validation is under development. Till now it was used on two patients by an expert surgeon. Computer guidance showed early promising results providing the surgeon with useful indications achieve a satisfactory prosthesis implant.

Introduction: In the last years matrix autologous chondrocyte transplantation becomes a possible solution in the treatment of chondral lesions. We develop an arthroscopic procedure for chondrocyte implant on hyaluronian-based scaffold.

Material and methods: Thirty-five patients treated using this technique achieved 3 years follow up. All the patients were clinically evaluated using IKDC score and with MRI or TC scan. In some Patients we performed a second look arthroscopy and histological evaluation.

Results: IKDC objective score improved after 12 months in all patients and the results were confirmed at 24 and 36 months of follow-up. The improving was obtained also according to IKDC subjective score. A second look arthroscopy showed healing of the defect with regenerated cartilage. The histological evaluation has demonstrated in 80% the hyaline type of new cartilage.

Conclusions: This matrix autologous chondrocyte transplantation procedure avoids the use of periosteal flap, simplify the surgical procedure and permit to perform the arthroscopic implant reducing the morbidity of the procedure. The preliminary clinical and histological results at 3 years follow-up are encouraging.

This study identifies parameters that allow to foresee the necessity of soft tissue release (STR) before surgery. Femoral and tibial morphotype were defined evaluating several radiological parameters. Intra-operative STR during surgery was correlated to radiographic parameters identified. 33 cases were analysed and divided in 2 groups, release (6) no release (27), statistical evaluation has been performed using Mann-Whitney test and contingency tables for most relevant parameters. Three parameters were measured on femur and four on tibia.

The results confirmed the usability of angle between femoral anatomical axis and transepicondylar axis ATA (p< 0.001) and between femoral mechanical axis and tangent to distal condyles MCA (p< 0.001 ) as predictors, among tibial parameters angle between mechanical axis and tangent to tibial plateaux gives good results (p=0.028).The use of contingency tables highlighted that the combined use of ATA and MCA, gives better specificity than the use of a single angle.