Background: Increased contact stress with a femoral resurfacing prosthesis implanted in the medial femoral condyle and a non-functional meniscus is of concern for potential deleterious effects on tibiofemoral contact mechanics.

Methods: Peak contact pressures were determined in seven fresh frozen human cadaveric specimens using a pressure sensitive sensor placed in the medial compartment above the menisci. A knee simulator was used to test each knee in static stance positions (5°/15°/30°/45°) and through 10 dynamic knee-flexion cycles (5°–45°) with single body weight ground reaction force (GRF) which was adjusted to the living body weight of the cadaver donor. All specimens were tested in three different conditions: Untreated knee (A); Flush implantation of a 20mm resurfacing prosthesis (HemiCAP^®) in the weight bearing area of the medial femoral condyle (B); Complete radial tear at the posterior horn of the medial meniscus with the femoral resurfacing device in place (C).

Results: On average, flush device implantation resulted in no statistically significant differences when compared to the untreated normal knee. The meniscal tear resulted in a significant increase of the mean maximum peak contact pressures by 63%, 57%, and 57% (all P ≤ 0.05) at 15°, 30° and 45° static stance positions and 78% (P ≤ 0.05) through the dynamic knee flexion cycle. No significant different maximum peak contact pressures were observed at 5° stance position.

Conclusion: Possible effects of reduced meniscal tissue and biomechanical integrity of the meniscus must be considered in an in-vivo application of the resurfacing device.

Aims: Prospectivemulti-centre study evaluating minimally invasive unicondylar knee arthroplasty (UKA). Methods: Between 1997 and 2001 435 UKA were performed using the minimally invasive technique according to Repicci. 420 patients with an average age of 66 years were evaluated after a follow up of 32 weeks. In 96,8% the medial and in 3,2% the lateral compartement were involved. The clinical results were evaluated with the Knee Society Clinical Rating System (KSS) and correlated with Body-Mass-Index (BMI) and pain, rated on a Visual Analogue Scale (VAS). Radiographical scoring were evaluated according to Ahlback. Results: The results of the KSS show a signiþcant postoperative increase of average 73 points. 86,8% patients were conþdent with the treatment. The statistical analysis revealed correlation between pain and patients age. BMI shows signiþcant correlation with all other parameters. Conclusion: Minimally invasive unicondylar knee arthroplasty shows very good results, espeically for pain and patientsñ conþdence. BMI and arthrosis of the patella might have the gratest inßuence for the outcome. Deþcient pre- and postoperative extension might be an unsolved problem.

Aim: Our aim was to evaluate the accuracy and reliability of both MRI and CT in estimating the patello-femoral alignement with the TT/TG (tibial tuberosity/trochlear groove) distance in 14 healthy probants.

Method: The TT/TG distance has been estimated in 28 healthy knees of 14 probants, 8 women and 6 men (age: 24 – 42) with a) MRI in an Esaote Arthroscan 0,2 Tesla Tomographer and b) CT in a General Electric Tomographer. This parameter was estimated in both imaging devices, first by overprojecting a tibial axial image through the tibial tuberosity onto an axial image through both femoral condyles and then by measuring the distance between the deepest point of the trochlear groove and the most prominent point of the TT. The parameter has been estimated twice by 3 well trained independent observers. The statistical evaluation was done with an unifactorial analysis of variance (ANOVA).

Results: Our results showed a good reproducibility (> 95%) of the TT/TG measurement in both methods: The intraobserver reliability was in CT, 0,008 ± 0,005mm and in MRI 0,03 ± 0,0017mm respectively. The interob-server reliability was 0,046 for the CT and 0,66 for the MRI. Interesting was that the average value of TT/TG by measuring with MRI (14 mm) was 3 mm less than the one measured with CT (17mm).

Conclusion: We concluded that in spite of the difference of the average values between MRI and CT the evaluation of the TT/TG parameter by means of MRI could be a good method for estimating this parameter thus avoiding radiation uptake.

Introduction: The goal of this prospective, randomized study is the functional evaluation of two different techniques of ACL reconstruction by using the bone-patella tendon (BPT) vs. hamstrings (ST/G).62 ACL-insufficient patients without any concommitent sport injuries took part in a prospective randomized study.

Material and Methods: Eighteen men and 13 women underwent ACL-reconstruction with BPT graft (Group I) with average age 29,87 (16–46) years. 31 patients (16 women and 15 men) with average age 34,23 (16–55) years underwent ACL-reconstruction using a quadrupled hamstrings graft (Group II). Both techniques were performed by using a press-fit and implant-free technique. We used the same accelerated rehabilitation protocol for both groups. The patients were evaluated by IKDC, Lysholm and Tegner scoring systems, KT 1000, one leg hop, isokinetics, internal torque, kneeling and knee walking test, 1 day preoperatively (VU), and 3 (NU I), 6 (NU II) and 12 months (NU III) postoperatively.

Results: One year postop.the results of Group II (30 patients classified as A and B) were according to IKDC scoring system better than those in Group I (Group I: 24 patients classified as A and B). We had similar results according to Lysholm-scoring evaluation (Group 11:95,61 points vs. 90,87 in Group I (p=0.017)) and Tegner-scoring (Group II: 7,07 vs. 6,61 in Group I (p=0.00)). According to the KT 1000 stability evaluation, there was no statistical significant difference between injured and uninjured knees in both groups. The evaluation of the strength of the hamstrings by isokinetics in both groups showed statistical significant differences (Group II: 90,34 Nm vs. 99,19 Nm in Group I, (p=0.008)). However, our results concerning internal torque evaluation were not statistical significant. The evaluation of one leg hop by comparing injured and non-injured leg showed a significant difference between group II and group I (Group II: 96% vs. 91% in Group I, (p=0.012)). We had worse results in Group I vs. Group II at kneelling and knee-walking-testings ((p=0.00)(p=0.00)), concerning the anterior knee pain.

Conclusion: From our results concerning IKDC, Lysholm, Tegner, kneeling and knee walking tests it seems that hamstrings can be recommended for ACL reconstruction. The isokinetic evaluation of hamstrings showed a statistical significant deficiency compaired to the BPT-group. But this result could not be confirmed with the internal torque evaluation and “one leg hop”-testing.

Aim of the study: To evaluate whether additional aperture fixation to distal fixation (two-point fixation or 2P) may diminish tibial tunnel enlargement compared to distal fixation alone (one-point fixation or1P).

Methods: Two groups of patients were evaluated. In group 1P (44pts.) the grafts were fixed on the tibial side, using two 4 mm Mersilene tapes tied over a 10 mm bone bridge created in the anterior cortex. In group 2P, an additional fixation, using 1 absorbable cross pin in 27 pts. and 2 absorbable cross pins (Rigid fix, Mitek) in 24 pts., was performed. AP and lateral radiographs as well as patients evaluation were performed 3, 6 and 12 months post-op. Tibial tunnel size was measured at the widest diameter in both AP and lateral radiographs.

Results: Tunnel enlargement occurred in both groups at 3 months post-op, but not thereafter. In the lateral radiographs, tunnel enlargement was significantly less in group 2P compared to group 1P (p< 0.05). No statistical relationship was found between tunnel enlargement and gender, age, IKDC, and KT 1000 side-to-side difference.

Conclusion: Additional tibial graft fixation with cross-pins seems to diminish tibial tunnel enlargement in the sagital plane. This may be explained by the fact that the cross pins inserted in the coronal plane, reduce tibial graft movements mainly in the sagital plane. The study supports the hypothesis that tibial graft micro-movements during the period of tendon healing to bone (up to 3m) play a role in tibial tunnel enlargement after ACL reconstruction using hamstrings.