• Patient history

• Patellofemoral complaints can be due to instability or pain or both.

• Patients with patellofemoral pain commonly complain of pain with walking up/down stairs and inclines or sitting for long periods of time.

• Onset of pain is often insidious, related to patellofemoral lateral malalignment/arthrosis or associated with patella instability with lateral tracking.¹

• Physical examination

• Gait evaluation may show valgus coronal plane alignment or excessive femoral anteversion/internal rotation and compensatory external tibial torsion.²

• An overloaded lateral patellar facet related to malalignment is commonly tender to compression or palpation, often with crepitus.¹

• The J-sign is common in patients with lateral patellar maltracking.

• Patients with instability commonly complain of apprehension with lateral patellar translation.

• Apprehension with increasing degrees of flexion can be a sign of trochlear dysplasia.³

• Resisted knee extension at varying degrees of flexion can be suggestive of a cartilage lesion in the patellofemoral articulation.¹

• Pain on stepping down with the contralateral leg suggests an articular lesion.²

• Imaging

• Standard radiographs (anteroposterior, 3-degree knee flexion weight-bearing posteroanterior, true lateral, and 30-degree knee flexion Merchant views)¹,⁴

▪ Patellofemoral arthrosis is most commonly seen on the lateral and Merchant views.

▪ Patellar tilt seen on Merchant view suggests lateral facet overload.⁴

• Magnetic resonance imaging (MRI)

▪ This can be valuable in evaluating patellofemoral articular cartilage integrity.

▪ Axial imaging can investigate the integrity of the medial retinacular structures in patients with traumatic dislocation.⁴

▪ MRI allows measurement of the tibial tubercle-trochlear groove (TT-TG) distance, with >20 mm being abnormal.⁴

▪ Can be used to measure the tibial tubercle-posterior cruciate ligament (TT-PCL) distance, with more than 24 mm being abnormal.⁵

• Computed tomography (CT)

▪ In lieu of MRI, CT can measure the TT-TG distance with >15-20 mm being abnormal.

▪ Mid-patella axial images at 15-, 30-, and 45-degree knee flexion can evaluate patellar tracking.¹

• Indications for anteromedial tibial tubercle transfer osteotomy

• Failed conservative measures for lateral patellofemoral arthrosis including physical therapy focused on the patellofemoral joint with emphasis on core strengthening and lower extremity mechanics/gait.

• Recurrent patellar instability or patellofemoral pain with radiographic and clinical lateral tracking. This can be performed in combination with medial patellofemoral reconstruction in recurrent patella instability patients.

• Intact medial facet and medial trochlear articular cartilage are needed to accept the transferred load for optimal outcomes.⁶

• Tourniquet (nonsterile)

• Arthroscope

• Arthroscopic cautery

• Two Army-Navy (Parker-Langenbeck) retractors

• Tonsil (Schnidt) clamp

• Electrocautery (Bovie)

• Cobb elevator

• Handheld sagittal saw (Smith & Nephew, Stryker Total Performance System [TPS] or equivalent) with a minimum ½-inch-wide, 2-inch-long straight blade

• Osteotome set, preferably Lambotte osteotomes

• Large-fragment set with 4.5-mm screws, including drill and countersink

• The patient is positioned supine on a regular operating table with a nonsterile tourniquet.

• A bump can be placed under the ipsilateral hip if the patient exhibits excessive external rotation of the leg on the operating table.

• The leg is exsanguinated, and a thigh tourniquet is inflated.

• Diagnostic arthroscopy is performed with standard anterolateral and anteromedial portals.

• Starting with an anteromedial viewing portal can allow optimal anterolateral portal placement to complete the lateral release as needed.

• Diagnostic arthroscopy focuses on the patellofemoral joint, specifically detailing the state of the articular cartilage.

• An anteromedializing tubercle osteotomy most efficiently unloads the lateral facet and the distal pole of the patella.

• If the lateral retinacular tissues are too tight to allow medialization of the patella, an arthroscopic lateral release is performed at this time. Open lateral lengthening is also an option.

• A 7- to 8-cm incision is made just lateral to the tibial tubercle starting just above the distal aspect of the patellar tendon.

• Full-thickness skin flaps are raised proximally 1-2 cm above the insertion of the patellar tendon and distally along the level of the proposed osteotomy. This is usually 6-10 cm distal to the patellar tendon insertion.