Table 1 Inclusion, exclusion and matching criteria for the patients with recurrent patella dislocation (RLPD group) and their ACL-deficient patients (ACL) in the study

Inclusion criteria for the RLPD group

 a. Patients with two or more patella dislocations

 b. Patients with a lateral dislocation of the patella and a positive apprehension test with clinical examination

 c. Patients aged between 12 and 30 years

Exclusion criteria for the RLPD group

 a. Patients with medial dislocation

 b. Bilateral patella instability at inclusion

 c. Severe trochlea dysplasia grade D (Dejour)

 d. Tibal Tuberosity Trochlear Groove (TT-TG) distance > 20 mm on CT

Inclusion criteria for ACL patients from the Norwegian Knee Ligament Registry (ACL)

 a. Patients with isolated ACL rupture verified both with clinical examination and MRI

 b. Patients aged between 12 and 30 years

 c. Knee symptoms indicating operative treatment

 d. Registered height and weight at time of operation

Matching criteria

 a. Matched by sex, age and body mass index (BMI) in that order (more specific; best BMI match within +/− 1 year)

 b. Two controls per case - data truncated into one average score