arthroscopically with a rigorous standardized aftercare in a plaster cast and with physiotherapy. The mean fol- low-up period was 16 months (9-18 months). During the follow-up examinations, the orthopaedic knee score (OAK) of the Swiss Society of Orthopaedics (SGO) was assessed. To improve objectivity, one experienced inves- tigator documented the a.-p. drawer with the “Kneelax3” machine in comparison to the uninjured contralateral side. Results: 21 Patients injured their ACL during sport activites and 1 while at work. The mean time from injury to the operation was 15,5 days (5-37 days). We found additional meniscus injuries in 6 patients. The patients were hospitalized for a of mean 1,5 nights (1-3 nights). The average return-to-work time was 8,8 weeks (2-20). We had 2 patients lost to follow-up and 5 patients re- quired revision (4 ACL reconstructions, 1 mobilisation after stiffness). Orthopaedic knee score showed a mean of 91,5 points out of 100 (78-98 points) and the a.-p. drawer difference compared to the uninjured side was a mean of 2,86 mm (0,99-5,90 mm). Conclusions: The “Healing response” is an easy pro- cedure to carry out without any additional iatrogenic trauma and is minimally invasive compared to recon- struction methods. However, our revision rate of 23% is relative high. Thus it has to be discussed if this procedure is the best treament approach in for highly active young patients. In considering other investigations with elderly study groups and better results, it appears that the use of the “healing response” procedure is most appropriate for patients with an lower level of activity and higher age. Primary Repair with Healing Stimulation Technique for Partial Tears of the Anterior Cruciate Ligament (SS-14). Alberto Gobbi, MD, Ramces Francisco, MD, Ariel Sandoval, MD, Paolo Arrigoni, MD Purpose: We analyzed the functional outcome of acute treatment for partial ACL tears involving either the anteromedial (AM) or the posterolateral (PL) bundle using suture-repair combined with a bone marrow stim- ulation (BMS) technique (microperforation). We hypoth- esized that knee stability could be restored and good functional outcome could be obtained with a simple primary repair technique. Methods: From January 2003 to December 2005, thirteen patients (mean age: 20 years) with partial ACL rupture underwent acute primary ACL repair of the torn ligament. The senior author performed all the surgeries within 2 weeks from injury and all the patients were required to complete a specific rehabilitation protocol. Parameters analysed included the standard knee scales (IKDC, Noyes, Lysholm and Tegner), SANE Score, Computer Knee Laxity Analysis and Deep Flexion Tests. Seven (7) patients had second look arthroscopy after signing an informed consent. The rest conceded to have a post-operative MRI for the re-evaluation of the re- paired ACL. Results: Preliminary Results revealed an average Ly- sholm score of 84%, Tegner score of 7, Noyes Score of 85% and Subjective score of 76.25%. IKDC score dem- onstrated that 60% of the patients had normal knee functions while 40% were nearly normal. Pivot shift test was negative and 80% of the patients had less than 3mm anteroposterior laxity. Conclusions: Based on the preliminary results, pri- mary ACL repair with BMS can lead to favourable results. However, further evaluation is recommended at longer follow-up to validate these findings. Accuracy of Knee MRI to Evaluate Osteochondral Lesions (SS-15). Pablo Adelino Narbona, MD, Guill- ermo Allende, MD, Julio Masquijo, MD, Luis Vazquez, MD Purpose: Determine the MRI diagnostic precision for assessment of osteochondral knee defects, and the con- cordance between the grading of such lesions by arthro- scopy with the Density Prototonic Fat Sat (DP Fat Sat) MRI. Type of study: Transversal with prospective data. Material and methods: Fifty knees of 49 patients (divided into 6 regions) were studied. Relationship be- tween surface of the lesions in mm 2 using a coefficient of variation 2mm2, and the grading of the lesion accord- ing to Outerbridge modify system, using arthroscopy as a standard pattern. The Wilcoxon test was used for comparison between medians with the significance of 95% confidence. To evaluate grading concordance was used, the kappa coefficient. Results: Osteochondral lesions were found in 48% of the cases (24/50). Comparing such data with the arthro- scopic findings, we found: sensibility 79.4%, specificity 99.3% and accuracy of 97%. Concerning the lesion size, the 53% of the small ones (0-20mm 2 ), 92% of the mod- erate (20-100mm 2 ) and the 100% of the large lesion (100mm 2 ) were underestimated by MRI. The average of underestimation was 37,2% (p  0,0004). Concor- dance of 70% with kappa coefficient (0.80) was obtained in relationship with grading of the lesions. Grade IV lesions presented the largest percentage of coincidence (77%). Conclusions: The DP Fat Sat MRI possesses a sen- sibility and specificity similar to those reported with e8 ABSTRACTS