BACKGROUND:Surgical treatment of young patients with recurrent lateral patella dislocation (RLDP) is often recommended because of loss of knee function that compromises their level of activity or even their daily life functioning. This situation is comparable to young patients with an anterior cruciate ligament (ACL) rupture. The purpose of this study was therefore to explore the time from injury to surgery and the pre-operative symptoms and knee function of young RLPD patients scheduled for stabilizing surgery and compare this group to age and sex-matched ACL-deficient patients. METHOD:Forty-seven patients with unilateral RLPD listed for isolated medial patellofemoral ligament reconstruction were included in the study (RLPD-group). This group was compared to an age, sex and BMI matched ACL patient group obtained from the Norwegian knee ligament registry (ACL-group) for the following outcome measures: the knee injury and osteoarthritis outcome score (KOOS) assessed on the day of surgery and time from injury to surgery. RESULTS:The RLPD-group scored significantly lower than the ACL-group for the three KOOS subscales "Pain" (73.6 vs. 79.8, p < 0.05), "Symptoms" (71.7 vs. 79.3, p < 0.05) and "ADL" (84.7 vs 89.5, p < 0.05). The lowest KOOS values were found for Sports/Recreation (53.5 vs. 51.3, p = 0.65) and Quality of life (37.6 vs. 36.7, p = 0.81). The average time from primary injury to surgery was 6 months for the ACL group and 31 months for the RLPD group. CONCLUSION:RLPD affected knee function as much as ACL deficiency, and was associated with more pain. Still the RLDP patients waited on average 5 times longer for surgery. TRIAL REGISTRATION:The patients with RLPD consisted of patients who were examined for possible recruitment for a concurrent prospective randomized controlled trial comparing conservative treatment and isolated surgical medial patellofemoral ligament (MPFL) reconstruction (Clinical trials no: NCT02263807 , October 2014).