Patellofemoral instability (PFI) is a common condition that may result from numerous underlying soft tissue and bony abnormalities, and can significantly impact the patients' quality of life and function. It is estimated that PFI affects between 5.8 and 29 out of every 100,000 children aged 10 to 17 years [1].

Patellar instability is defined as a symptomatic deficiency of the passive constraint such that the patella may escape partially or completely from its anatomic position with respect to the femoral trochlea under the influence of a displacing force. Such a displacing force could be generated by muscle tension, movement, and/or externally applied forces [2].

The etiology of RPD is multifactorial, including medial patellofemoral ligament (MPFL) injuries, abnormally lateralized tibial tubercle (TT), femoral trochlear dysplasia, patella alta, increased femoral anteversion and genu valgum [3,5].

The MPFL is the primary static soft tissue restraint which restrains against lateral subluxation and dislocation of the patella, especially between 0° and 30° of knee flexion [3]. And the MPTL act as secondary restraint[4.]

Therefore, injury or deficiency of MPFL is one of the predisposing factors for RPD.Therefore, an anatomical repair MPFL is necessary to prevent redislocation of patella [6].

MPFL reconstruction is widely recognized as an important component of the current treatment for recurrent patellar instability, MPTL reconstruction improve medial patellar stabilization, patellar tilt, patellar rotation as well as decreases stress on MPFL.A large number of surgical methods for treating patellofemoral instability have been described in various studies, but the best method is still controversial[7].

This study is prepared to compare the results of MPFL reconstruction versus combined MPFL and MPTL reconstruction in management of recurrent lateral patellar dislocation in children .

Patellofemoral instability (PFI) is a common condition that may result from numerous underlying soft tissue and bony abnormalities, and can significantly impact the patients' quality of life and function. It is estimated that PFI affects between 5.8 and 29 out of every 100,000 children aged 10 to 17 years [1].

Patellar instability is defined as a symptomatic deficiency of the passive constraint such that the patella may escape partially or completely from its anatomic position with respect to the femoral trochlea under the influence of a displacing force. Such a displacing force could be generated by muscle tension, movement, and/or externally applied forces [2].

The etiology of RPD is multifactorial, including medial patellofemoral ligament (MPFL) injuries, abnormally lateralized tibial tubercle (TT), femoral trochlear dysplasia, patella alta, increased femoral anteversion and genu valgum [3,5].

The MPFL is the primary static soft tissue restraint which restrains against lateral subluxation and dislocation of the patella, especially between 0° and 30° of knee flexion [3]. And the MPTL act as secondary restraint[4.]

Therefore, injury or deficiency of MPFL is one of the predisposing factors for RPD.Therefore, an anatomical repair MPFL is necessary to prevent redislocation of patella [6].

MPFL reconstruction is widely recognized as an important component of the current treatment for recurrent patellar instability, MPTL reconstruction improve medial patellar stabilization, patellar tilt, patellar rotation as well as decreases stress on MPFL.A large number of surgical methods for treating patellofemoral instability have been described in various studies, but the best method is still controversial[7].

This study is prepared to compare the results of MPFL reconstruction versus combined MPFL and MPTL reconstruction in management of recurrent lateral patellar dislocation in children .

2.4.1- Type of the study: Randomised controlled trial . 2.4. 2- Study Setting: Arthroscopy Unit, Orthopaedic and trauma Surgery department, Assiut University Hospital, Assiut, Egypt.

2.4. 3- Study subjects: a. Inclusion criteria:

1- Age : <18years old. 2- History of recurrent lateral patellar dislocation (>2 episodes). 3- Failure of conservative treatment.

• b. Exclusion criteria:

  1. Active infection.

  2. inflammatory joint disorders.

  3. trochlear dysplasia

  4. previous surgeries related to patella dislocation.

     c. Sample Size Calculation: Based on determining the main outcome variable, the estimated minimum required sample size is 22 pediatric patients (11 patients in each group).

     The sample was calculated using G*Power software version 3.1.9.2, based on the following assumption : The main outcome variable is the difference in mean postoperative functional outcome score between children with recurrent lateral patellar dislocation treated with Medial Patellofemoral Ligament (MPFL) reconstruction alone versus those treated with combined MPFL and Medial Patellotibial Ligament (MPTL) reconstruction.

     d. Method of Randomization : Computer generated randomization into2 groups (A) : MPFL reconstruction alone and group (B) :combined MPFL and MPTL reconstruction in management of recurrent lateral patellar dislocation in children.

     The primary statistical test is an independent samples t-test to detect the difference between the two groups.

     Alpha = 0.05 Power = 0.80 Effect size (d) = 1.1

     2.4.4 -Study tools (in detail, e.g., lab methods, instruments, steps, chemicals): All patients meeting the inclusions criteria will be allocated .

     - History taking including :-

     1. Thorough history evaluation (patient data) including name, age, sex, telephone number, address and comorbidties .

     2. Complaint and its duration (pain , swelling , deformity, instability ).

     3. Medical history and previous operations.

        • Clinical evaluation and apropriate examination :-

     1. General examination.

     2. knee and patellar examination including :-

        • Inspection of the patients knee , deformity , odema and ROM ( range of motion ).

        • Look ( skin discoloration, scar, ulcer, signs of infection ).

        • Feel ( tenderness and apprehension test ).

        • Move ( starting with active movement followed by passive movement ( compare both sides ) to assesROM (range of motion ) and place of patella during flexion and extension.

        • Asses ( other knee ligaments laxity , tear or generalized joint laxity) - Functional assessment by clinical scores. Kujala Lysholm IKDC - Radiological assessment: Plain x-rays ( AP, lateral and axial views) To measure Insall-Salvati Ratio Caton-Duchamp's Ratio Patella-Plateau Angle Rotational profile MSCT. (To measure TT-TG and rotational malalignment of the femur and tibia(

          - Anathesia : according to situation either spinal or general.

          • Surgical technique :Medial parapatellar approach

        • Medial Patellofemoral Ligament (MPFL) Reconstruction Reconstruction of the medial patellofemoral ligament was performed using the superficial middle portion of the quadriceps tendon as an autograft. The graft length was harvested to be approximately 1 inch longer than the measured distance between the medial border of the patella and the adductor tubercle. A soft-tissue canal was created along the native course of the MPFL, allowing passage of the graft without bone tunnels. And at 30° flexion, the femoral end of the graft was secured to the adductor magnus tendon and reinforced by suturing to the periosteum over the adductor tubercle using non-absorbable sutures, thereby reproducing the anatomical attachment of the native MPFL.

        • Medial Patellotibial Ligament (MPTL) Reconstruction Reconstruction of the medial patellotibial ligament was carried out using the medial portion of the patellar tendon. And at 90° flexion, the graft was fixed in a subperiosteal fashion approximately 1.5 cm distal to the tibial plateau, oriented at an angle of 25° medially, to replicate the native anatomical direction of the MPTL. Fixation was performed using non-absorbable sutures, ensuring stable graft positioning while preserving the physis Finally,the wound is closed in layers.

          - Follow-up schedule : 2 weeks for removal stitches. B) 3 months : Follow up by x-ray and clinical scores. C) 6 months : follow up by x- ray and clincal scores D)12 months : follow up by x-ray, clinical scores and Rotational profile MSCT .

     2.4.5 -Research outcome measures:

     a. Primary (main): Comparing results of MPFL reconstruction alone versus combined MPFL and MPTL reconstruction in management of recurrent lateral patellar dislocation in children.

     Secondary (subsidiary):

     Adress risk factors of patellar dislocation & redislocation after surgery.

Inclusion Criteria:a. Inclusion criteria:

1. Age : <18years old.
2. History of recurrent lateral patellar dislocation (>2 episodes).
3. Failure of conservative treatment. -

Exclusion Criteria: b. Exclusion criteria:

1. Active infection.
2. inflammatory joint disorders.
3. trochlear dysplasia
4. previous surgeries related to patella dislocation -