neuromuscular function causes abnormal high strains that lead to micro tears and the syndrome of Infra patella tendonitis. These forces are present for micro seconds which make it very difficult to measure in vivo We therefore used the LifemodR system previously validated to measure joint forces to simulate abnormal eccentric forces and then calculate the strain created in the infra- patella tendon We used this data to design a novel Eccentric Ergometer to test in vivo if eccentric neuro- muscular control is worse in people suffering from in- frapatella tendonitis Method: In order to evaluate the influence different ec- centric muscle forces on the infrapatella tendon, a three- dimensional dynamic computer model of a human sub- ject pedalling an eccentric exercise cycle (GrucoxR) was constructed with the LifemodR software package. One knee of the modelled human subject was detailed by importing 3D models of the patella, distal femoral head and proximal head of the tibia, all of which were con- structed from segmentations of MRI scans of the test subject’s knee, including the articular cartilage. The MRI data are also used to orientate the modelled ligaments. Actual recorded motion and pedal force data from the same human test subject pedalling our eccentric exercise cycle are used to drive the model during the inverse dynamic simulation phase. Validation of the final model is provided by using electromyography (EMG) data re- corded from the subject. The model comes into its own when used in forward dynamics mode to investigate the effects of poor muscular control on infrapatella tendon strain. We used this data to design a new ergometer where the amount of force generated can be measured and controlled. Our study includes 20 subjects with in- frapatella tendonitis confirmed with MRI scans, and 20 matched controls with no history or signs of infrapatella tendonitis on MRI. Eccentric control was measured with the GRUCOX ergometer Results: Simulating abnormal eccentric neuromuscular control with LifemodR we calculated that the forces created in the infrapatella tendon is higher than can be physiological tolerated Subjects with infrapatella tendon- itis showed a statistically significant decrease in eccen- tric neuro muscular control. Conclusion: Abnormal eccentric neuromuscular contol of the quadriceps muscle contributes to infrapatella ten- donitis. Paper 22: Arthroscopic Treatment of the Iliotibial Band Syndrome STEPHANE JAMBOU, MD, FRANCE,PRE- SENTING AUTHOR FREDERICK MICHELS, MD, BELGIUM MICHEL ALLARD,FRANCE VINCENT BOUSQUET,FRANCE PHILIPPE COLOMBET, MD, FRANCE CHRISTOPHE DE LAVIGNE,FRANCE ABSTRACT Objective: Iliotibial Band Syndrome(ITBS) is an over- use injury mainly affecting runners. The initial treatment is conserative therapy. In recalcitrant cases surgery is indicated. The conventional technique is lengthening of the iliotibial tract(ITT) and removing a section of the posterior aspect of the ITT. The aim of this study was to evaluate the results of an arthroscopic technique to treat ITBS. Methods: Thirty six patients with an ITBS resistant to conservative therapy were managed arthroscopically. Thirty three were available for follow up. All patients had at least 6 months follow up with an average of 2 years 4 months. All the patients were recreational or professional athletes: long distance running(22), triath- lon(5), soccer(1), rugby(3), athletics(3), swimming(1), fencing(1), basketball(1). There were 15 women and 21 men. The mean age was 31,1 years (range 19 to 44). All the patients had suffered from the ITBS for at least one year before passing to surgery. In all patients the diag- nosis was confirmed by ultraonography or magnetic res- onance imaging. We used a standardized arthroscopic technique. The patient is placed in supine position with the leg in 30 degrees of flexion. The joint space is inspected through the anteromedial and anterolateral portals. The lateral synovial recess is resected through a superolateral portal. A drain is placed during 24 hours. Results: The procedure was well tolerated in all patients. In two patients a meniscal lesion was found, which required treatment. All patients went back to sports after 2 to 3 months. In 32 patients the results were good or excellent(no pain or much less pain in activity, complete return to preoperative sport level). One patient with only a fair result had associated cartilage lesions of the fem- oral condyle. Discussion and conclusion: In cadaveric studies it was found that the ITBS was associated with inflammation of fibrous strands anchored to the distal femur. Based on these findings an arthroscopic technique was developed. Our results show that arthroscopic treatment of resistant ITBS is a valid option with a consistently good outcome. In addition, this arthroscopic approach allows excluding or treating other intra-articular pathology. Paper 23: Biomechanical Comparison of two Double- Row Rotator Cuff Repair Techniques Utilizing Bio- absorbable Anchors (Corkscrew with Fiberwire vs. e347 ABSTRACTS