present without sensation even to direct probing) At 15 years post-op, a T1 rho MRI study was performed, and at 16 years post-op, a repeat Tc bone scan was performed. Reports of his subjective sensation throughout the 16 year time span were documented. Results: The subject reported no PF Pain At ANY Time, during the 17 years. The Tc99m- MDP bone scan studies performed at time zero and at 16 years post-op were completely normal (indicating the presence of Osseous/ Joint Homeostasis) The T1 rho study performed at 15 years post-op was 3+ abnormal (indicating substantial dimin- ishment in proteoglycan content) in the geographic region of the bilateral Grade 3, but Asymptomatic, CMP. Conclusions: Even advanced Grade 3 CMP can exist Asymptomatically without progression and be metaboli- cally stable (bone scan negative - an objective,metabolic marker of Joint Homeostasis) for extended periods of time. The + T1 rho study does not likely represent pathology, but rather, Normal, asymptomatic, age-related changes (diminished proteoglycan content) - that probably exists in Vast numbers in this advanced middle-aged population. Clinical Implications: The results of this study have potentially profound implications for orthopedic sur- geons,researchers, radiologists, and physical therapists to be Extremely Cautious to Not “Over-interpret” the MRI finding of a + T1 rho lesion in this clinical setting (Middle- Aged) as necessarily “pathological” and therefore serving as a rationale for aggressive cartilage-oriented operative procedures in a symptomatic patient - Where the Actual Etiology of the perceived PF pain may well be due to factors completely unrelated to the articular cartilage: (e.g.: transient synovial soft-tissue impingement, and/or intra- osseous hyper-pressure, etc.). Category: Knee - Patellofemoral instability Paper #120: Lateral Release for Anterior Knee Pain Without Instability. Outcome Evaluation at Long Term Follow Up LUCA DEI GIUDICI, MD, ITALY ANDREA FAINI, MD, ITALY VALENTINO COPPA, MD, ITALY ANTONIO GIGANTE, ITALY Clinical Orthopaedic, DISCLIMO, Università Politecnica delle Marche, Ancona, An, ITALY SUMMARY Treatment of patellofemoral pain syndrome with lateral retinaculum release. ABSTRACT DATA Introduction: In a subset of patients with anterior knee pain (AKP) no predisposing factors can be identified, apart from a vague imbalance of the extensor mechanism arising from weakness of vastus medialis obliquus or overcostraint from lateral retinaculum. In those rare cases, after failure of nonsurgical therapy, current treatment consists of surgical transection of the lateral retinaculum release (LR) with an open or arthroscopic technique. Historically LR was performed alone to treat pathologies like patellar instability that needed a different approach like a trans- position. Moreover, literature suggests that results ob- tained by the LR in the short term decrease after few years of follow-up, advising its use as a corollary act during other procedures. Aim of the present paper was to analyze at a long-term follow-up a cohort of patients suffering from AKP and treated with LR, in terms of subjective scores, pain reduction, return to activities, and patello-femoral alignment, trying to describe indications for this procedure. Materials and Methods: A retrospective review of patient with AKP that performed a Lyonnese CT scan and underwent LR was performed. Exclusion criteria were: missing information, history of patellar dislocation, diag- nosed pathologies different from a patellofemoral disorder, associated pathologies, traumatic injuries, and disorders affecting the collagenous tissue. 54 agreed to undergo a follow-up examination, and signed the informed consent for the participation in this study. Demographic, clinical, radiological data were analyzed, along with NRS, Tegner, and Kujala scores. Mean follow up was 74 month; patients were divided in two groups according to the presence of subjective instability. Results: Instability group was made of 21 patients, while stability group was made of 33 patients. At follow up the benefit of LR was statistically significant for all the scores with a p<0,0001 in both groups. The parameters used for radiological evaluation of the joint alignment were not affected by the surgery, showing a non statistically signifi- cant difference for both groups. Comparing the two groups revealed no statistical difference in terms of NRS score and Tegner level, respectively with a p<0,151 and p<0,543. An interesting correlation was found, instead, when comparing the Kujala scores between the groups, with a p<0,00145 in favor of the stability group. Discussion: The main finding of this paper is that LR appears to be effective in treating patello-femoral pain, in those patients without malalignment and without subjec- tive sensation of instability. This paper also depicts worst results with LR as the only treatment for a patellofemoral pain with instability. In conclusion, the paper demonstrates an actual efficacy of LR able to obtain a good outcome and patient satisfaction even on the long term. It should not be indicated for the treatment of instability because the results are worse and tend to decrease over time, and for this pathology should only be a secondary concomitant proce- dure. More well-designed studies with clearly de?ned inclusion criteria, standardized methods of assessment, and adequate follow-up are certainly needed, in order to understand the missing aspects, and to uniform the scien- tific community in regards of the effectiveness of LR. Category: Knee - Patellofemoral instability Paper #121: Subchondroplasty for the Treatment of Post-Traumatic Bone Marrow Lesions of the Medial Femoral Condyle in a Pre-Clinical Canine Model SETH LAWRENCE SHERMAN, MD, UNITED STATES e94 2017 ISAKOS ABSTRACTS