AOSSM/AANA Specialty Day 2020-Handout 1

Handout 1 - TTO + MPFL_ Worth It!

Pdf Summary

This presentation by Dr. Andrew J. Cosgarea at the 2020 AOSSM/AANA Specialty Day reviews the surgical management of recurrent patellar instability, focusing on combining tibial tubercle osteotomy (TTO) with medial patellofemoral ligament reconstruction (MPFLR). Patellar stability depends on dynamic muscle action, passive soft tissue restraints, and osteochondral geometry—including factors like femoral anteversion, trochlear dysplasia, patella alta, Q-angle, lateralized tibial tuberosity, and valgus alignment.<br /><br />Recurrent patellar instability often arises from a combination of medial soft tissue insufficiency and bony malalignment. Isolated MPFLR can be effective, especially in patients with normal alignment and tracking, showing low revision rates and good return to sports. However, patients with risk factors such as elevated tibial tuberosity-trochlear groove (TT-TG) distance (>15mm), patella alta, positive J-sign indicating maltracking, or trochlear dysplasia often require adjunctive bony procedures for optimal outcomes.<br /><br />TTO—performed as Elmslie-Trillat (medialization), Fulkerson (anteromedialization), or distalizing osteotomy—corrects malalignment by medializing and/or anteriorizing and/or distalizing the tibial tubercle to improve patellar tracking, reduce lateral joint pressures, and facilitate earlier patellar engagement in trochlear groove. Biomechanical studies show that lateralized tuberosity increases MPFL graft tension and patellofemoral pressures, justifying combined TTO and MPFLR in malaligned patients.<br /><br />Clinical cases illustrate how surgical planning is individualized based on alignment parameters (TT-TG distance, Caton-Deschamps index for patella alta), presence of cartilage lesions, and soft tissue status. Medialization alone may suffice for isolated lateralization; anteromedialization is preferred when distal or lateral chondral lesions coexist; distalization is added for patella alta.<br /><br />TTO complications are not uncommon and include delayed union (up to 23%), painful hardware, and rare fractures. The choice of fixation screws (3.5mm vs 4.5mm) influences complication rates. Careful patient selection and surgical technique are essential to balance risks and benefits.<br /><br />In summary, combined TTO and MPFLR ("TTO + MPFL") is "worth it" for patients with recurrent instability and malalignment. Isolated MPFLR is reserved for those with normal alignment and tracking, while osteotomy adjuncts address biomechanical contributors to instability and help optimize graft function and clinical outcomes.

Keywords

recurrent patellar instability

tibial tubercle osteotomy (TTO)

medial patellofemoral ligament reconstruction (MPFLR)

patellar stability

TT-TG distance

patella alta

trochlear dysplasia

anteromedialization

patellar tracking

surgical complications