The objective of the present study will be to evaluate the clinical patellofemoral joint function (primary endpoint) and radiographically the patellofemoral arthritic degeneration (secondary endpoint) of of MPFL reconstruction with fascia lata allograft at a minimum follow-up of 2, 5 and 10 years in a group of 25 patients.

Patellofemoral disorders make up about 20% of all knee pathologies and are often a source of diagnostic and therapeutic doubts for the orthopedic surgeon. In fact, the origin of this type of disorder is multifactorial and they can occur in the form of a large variety of clinical pictures with different penetrance in each patient.

In accordance with the classification of Dejour et al., the instability of the patella can be divided into traumatic and a-traumatic (recurrent or habitual). The latter patients may present a variety of anatomical anomalies that predispose to dislocation: patella hypoplasia, genu recurvatum, conditions of ligament hyperlassity, hypoplastic external femoral condyle, trochlear dysplasia, high patella, torsional defects of the lower limb.

The incidence of patella dislocation is estimated to be 5.8 cases per 100,000 people, with values that become five times higher in patients aged between 10 and 17 years. Conservative treatment is preferable in the first case of acute dislocation, however the recurrence of this episode occurs in a percentage equal to 15 - 44% in these subjects.

Many surgical interventions have been described to correct the various factors that predispose to patellofemoral instability, with variable success rates (72% with the Hauser technique and 93% with the Roux-Goldthwait technique, 73% with that of Fielding et at. and 78% with that of Trillat. after a long follow-up.

On the other hand, Crosby and Insall, Arnbjornsson et al. and Marcacci et al. have demonstrated a similar clinical outcome in long-term controlled studies but an increase in degenerative changes in operated patients compared to patients treated conservatively. This can be explained by the fact that often a single procedure is not sufficient on its own to resolve such a complex pathology, or with the fact that the operations used so far excessively increase the pressures on the patellofemoral cartilage with subsequent arthrosic degeneration.

The medial patello-femoral ligament (MPFL) is one of the main stabilizers of the patella in its movement on the femur; numerous studies have recently shown that this ligament is damaged in almost all cases, thus recognizing the role of structure that most limits the patella in its lateral dislocation to the MPFL (biomechanically speaking about 50 - 60% of the force). Following these studies, the reconstruction of the MPFL as an elective treatment for relapsing patella dislocation has recently been proposed. Currently, countless surgical techniques have been proposed that use various types of grafts: autologous tendons (the first in 1990 from Suganuma et al.), donor tendons (allograft) and synthetic ligaments.

Our team recently developed a minimally invasive MPFL reconstruction technique using an allograft tendon of the fascia lata. The rationale for this technique is to stabilize the patella and limit medium-long term patellofemoral arthritic degeneration by restoring the MPFL in the most anatomical way possible, not using a tubular graft but an aponevrosis with biomechanical characteristics similar to the MPFL native. The MPFL reconstruction can be used alone or in association with the realignment of the extensor system by transposition of the anterior tibial tuberosity, managing to correct most of the recurrent patellofemoral instabilities. Only in very serious particular cases is it necessary perform additional procedures that are more invasive and have a more uncertain clinical result (such as Trocleoplasty).

The objective of the present study will be to evaluate the clinical patellofemoral joint function (primary endpoint) and radiographically the patellofemoral arthritic degeneration (secondary endpoint) of of MPFL reconstruction with fascia lata allograft at a minimum follow-up of 2, 5 and 10 years in a group of 25 patients.

Sample is represented by 25 patients underwent MPFL reconstruction using a minimally invasive technique using a donor-sided fascia tendon (allograft) performed at the Rizzoli Orthopedic Institute between 2011 and 2015 by the team of Prof. Marcacci.

Any concomitant treatments: treatment of associated meniscal lesions (meniscectomy), reconstruction of the anterior cruciate ligament (ACL), realignment of the extensor system by transposition of the anterior tibial tuberosity (intervention by Elmsile-Trillat).

Follow-up visit will be carried out at 2, 5 and 10 years of average follow-up. The "non parametric Wilcoxon" and "paired Student's t-test" tests will be used to determine the changes between the various follow-up intervals in the outcome measurements respectively for the non-parametric variables (Tegner activity level) and for the parametric ones ( SF-12 test, VAS pain test, KOOS test, Kujala test, "tilt" and "sulcus" angles, "Insall-Salvati" report).

The changes between the various follow-up intervals in the objective IKDC score and in the Iwano score will be assessed by means of the "Pearson chi-square test".

All "p values" will be 2-tailed; the significance level will be defined at p ≤ 0.05.

Inclusion Criteria:

• The potential person is of legal age, capable of providing informed consent and must sign the Informed Consent Form approved by the Ethics Committee (EC).
• Diagnosis of MPFL injury, performed before surgery, documented by Magnetic Resonance Imaging (MRI) of the affected knee.
• Absence of osteochondral lesions larger than 3 cm2 at the baseline.
• The contralateral knee was and is asymptomatic, stable and functional.
• The patient must be physically and mentally inclined and must have completed post-operative rehabilitation according to the protocol provided at the time of discharge.

Exclusion Criteria:

• Local or systemic infection
• Knee osteoarthritis documented radiographically at baseline
• Articular cartilage injury greater than grade I of Outerbridge detected during surgery.
• History of anaphylactic reaction.
• Systemic therapy with all types of corticosteroids or immunosuppressants in the 30 days prior to surgery.
• Evidence of osteonecrosis in the involved knee.
• History of rheumatoid arthritis, inflammatory arthritis or autoimmune pathologies.
• Neurological pathologies or conditions that the patient is unsuitable for the rehabilitation protocol.
• Untreated meniscal tissue loss greater than 50% at baseline.
• State of pregnancy.
• Obese or with body mass index BMI> 30 kg / m2.
• Association of Trocleoplasty (intervention that produces degenerative changes in the joint in high apercent).