Tibial Tuberosity transfer

Patella tracking is governed by a complex interaction between soft issue and bony structures. The bony structures that control patella stability are trochlea dysplasia, patella height and tibial tuberosity trochlea groove distance(TT-TG). Patella lateral tracking is common in patients with patella femoral pain and also with patella instability. Hence tibial tuberosity transfer is a well established technique in the management of both patella instability and patellofemoral pain.

Medialisation of the patella was done indiscriminately for non-anatomical reasons of patella instability. Hence the procedure historically has high complication rate. With better understanding of the various factors contributing to patella maltracking, a combination approach is now used to correct TT-TG distance and provide medial passive stabilisers like the MPFL at the same time.

The decision on tibial tuberosity transfer is made for PF pain/instability after

  1. Clinical examination
  2. Imaging measurement of TT-TG distance and patella height
  3. Arthroscopic assessment of the pattern of articular cartilage damage

It is difficult is place a single numerical value of TT-TG distance as indication for surgery but a distance of less than 1.5 makes it less likely necessary. measurements can be made with both CT and MRI.

Technical tips

  1. Mark the proximal extent of the osteotomy
  2. The author prefers a low energy osteotomy without use of a saw
  3. Keep the distal hinge narrow but retain distal soft tissue attachment
  4. For Distalisation osteotomy mark the pre-planned amount of distal tuberosity to be resected as shown
  5. Take care about the length and obliquity of the osteotomy
  6. Fixation is best achieved with 2 x 4.5 large fragment screws with screw heads countersunk so they do not cause irritation

Rehabilitation

  1. weight bearing mobilisation in an extension splint
  2. Intermittent range of motion outside splint started early
  3. Keep splint for all walking until 6 weeks

Clinical Assessment

  1. Hyperlaxity score(see picture)
  2. Beighton P, Horan F. Orthopaedic aspects of the Ehlers Danlos syndrome. J Bone Joint Surg Br. 1969;51-B:444-453.
  3. Coronal and rotational alignment
  4. Flat feet
  5. Quadriceps and core strength
  6. Functional valgus on single leg squat
  7. Lateral patella eversion
  8. Patella displacement
  9. Tibial tuberosity offset

Radiological assessment to look at soft tissue and bony constituents and also to assess Patellofemoral cartilage damage

Imaging in patellofemoral instability: an abnormality-based approach.

  1. Saggin PR, Saggin JI, Dejour D.
  2. Sports Med Arthrosc. 2012 Sep;20(3):145-51