In a single surgical center, 213 consecutive patients with 221 knees were surgically treated for recurrent lateral patellar dislocation between 07/2010 and 12/2016. All patients obtained dynamic reconstruction of the MPFL with detachment of the gracilis tendon at the pes anserinus while maintaining the proximal origin at the gracilis muscle. Patellar fixation was performed by oblique transpatellar tunnel transfer and tenodesis screw. Follow-up data including Kujala-, BANFF- and Norwich patellar instability score as well as Return-to-Sport and pain level were collected at a minimum follow-up of 2 years

Patients were identified through the hospitals database using OPS-Codes for MPFL reconstruction. The included surgeries were performed from 07/2010 to 12/2016 in a single orthopedic hospital.

Inclusion criteria:

• Dynamic MPFL-reconstruction (primary and revision surgery) including cartilage procedure
• Age of 18 years or older at a minimum of 24 months follow up

Exclusion criteria:

• Diagnosis of connective tissue disease

• Neurological diseases including patella associated spasticity and

• Concomitant alignment correction surgery including femoral/tibial osteotomy, trochleoplasty and tibial tubercle transfer

  213 Patients with 221 knees (8 bilateral) met the inclusion criteria. All patients were contacted by mail or phone to independently answer questionnaires.

Surgical technique:

The technique was performed according to the description by Ostermeier et al.. Briefly, the gracilis tendon is detached at its insertion site at the pes anserinus after opening the sartorius fascia. Instead of transferring the tendon through a subligamentous tunnel of the medial collateral ligament, as detailed in the original description of the technique, the tendon was passed around the incised sartorius fascia. From around the sartorius fascia the gracilis tendon is shuttled subcutaneously to the medial patellar margin, allowing the sartorius fascia to act as a pulley for the transferred tendon. Due to the dynamic reconstruction technique, the course of the graft appears to be more oblique compared to the static technique with femoral fixation at Schöttle's point. Fixation of the tendon is achieved by passing it through a transpatellar drill hole extending from the proximal medial patellar margin to the lateral patellar margin. The tendon is then tensioned with the knee in 30 degrees of flexion and fixed with a bioabsorbable tenodesis screw.

Data collection was performed by self-administered questionnaires, which were sent to the patients.

The medical records and radiographs of all patients were reviewed for demographic information (age, sex) and to identify complications related to the surgical procedure. Complications were categorized as major if the patient returned to the operating room or required hospitalization after the index procedure. Complications were categorized as minor complications if they were treated on an outpatient basis.

Rating of the results was performed using the Kujala score, the Norwich Patellar Instability Score and the BANFF Score.

Pain level was recorded using the visual analogue scale (VAS, 0 = no pain, 10 = severe pain). General satisfaction with treatment outcomes was evaluated by questionnaire (1 = excellent, 2 = very good, 3 = good, 4 = fair, 5 = poor, 6 = very poor) and by asking patients whether they would undergo the procedure again. Furthermore, information on patient characteristics, recurrence of dislocation, revision surgery, and other postoperative complications were recorded.

Postoperative x-rays were analyzed concerning intraoperative complications (e.g. fractures or patellar drill hole malpositioning).

Inclusion Criteria:

• Patients with MPFL reconstruction and possible accompanying interventions
• Age >18 years

Exclusion Criteria:

• Known hereditary connective tissue diseases (e.g. Ehlers-Danlos syndrome)
• Known neurogenic diseases
• Significant further musculoskeletal disorders

Patients were identified through the hospitals database using OPS-Codes for MPFL reconstruction.