The FDR (Femoral Derotaton) Trail.

Introduction:

Gait deviations in children may be caused by excessive femoral anteversion (AV). This rotational deformity is usually self-limiting but is a common cause of parental concern. Femoral anteversion is an inward twisting (rotation) of the femur. Excessive femoral anteversion causes the patients knees and feet to turn inwards and have a "pigeon-toed" appearance. The AV angle can be measured in the transverse plane by a line through the centre of the femoral head and neck and a tangential line across of the posterior femoral condyles. In the majority of cases of increased femoral AV, normalization occurs spontaneously during growth.

Persisting excessive femoral torsion after the age of 8 years may lead to tripping and anterior hip and knee pain. Recent studies have shown that increased internal rotation is a risk factor for patellofemoral instability and may result in patellofemoral contact pressure.

There are no studies supporting conservative treatment with physiotherapy or braces. Femoral derotational osteotomy is the gold standard to correct symptomatic patients with increased femoral AV. Several techniques have been described and there is no clear evidence in the literature supporting which surgical technique or implant that should be used (3). Traditionally these patients are treated with an open osteotomy and plate and screw fixation. In recent years intramedullary nailing with adolescent interlocking nail has been described both for rotational osteotomies and femoral fractures. With a lateral trochanteric entry point this has been shown to be a safe method. Percutaneous osteotomy and intramedullary nailing is considered a less invasive technique compared with open osteotomy and plate and screw fixation.

Study aims:

The investigators want to compare percutaneous osteotomy and intramedullary nailing with an open approach and plating with interlocking screws, in a randomized, controlled single-center trial. Our hypothesis is that percutaneous osteotomy and intramedullary nailing is non-inferior in the treatment of increased femoral AV, compared to open approach with plate fixation.

The primary outcome measure is to measure the accuracy of the derotation at 12 months by CT scan.

Study design and methodology:

The study is a randomized non-inferiority trail comparing operative treatment of patients with symptomatic increased idiopathic femoral anteversion. There are two arms: (1) Open approach and plating and (2) percutaneous osteotomy and intramedullary nailing. The allocation ratio is 1:1.We will recruit patients in the age 10-18 years of age, referred to the Orthopedic department, Oslo University Hospital. A pediatric orthopedic surgeon will verify that the patient meets the inclusion criteria, and the patient will be given thorough oral and written information. After signed consent, the randomization allocation to treatment method will be performed by means of a web-solution made by NTNU WebCRF system with the approval from the OUS Head of Patient Security.

Follow-up:

The study patients will be followed-up over a one year period (6 weeks, 12 weeks, 12 months). All patients will be tested with 3 d gait analysis at 12 months and will be compared with the patients preoperativ 3 D gait analysis. All reoperations will be recorded.

Inclusion criteria

• Radiographic findings: Femoral AV angle ≥ 30°
• Age 10-18 years.
• Hip or/and knee pain
• Less than 15 degrees external rotation of the hips

Exclusion criteria

• Patients will be excluded from the study if they meet any of the following criteria:

• Previous femoral injury or illness which reduces the function of the extremity
• Systemic or chronic injury or illness which reduces the function of the extremity
• If the patient is not able to comply with study procedures