J-Lat improves patellar tracking in cases of lateral patella subluxation and dislocation. How it Works This J-Lat Knee Support helps guide the patella back into proper alignment with gentle pressure from the lateral to medial direction. Compression surrounding the patella will help keep it in the patello-femoral groove. Design Theory The J-Lat provides lateral tracking control by means of two elastic straps. These straps stretch over J shaped tubing and help guide patella into the femoral groove.