Tibial tuberosity transfer

Written by Dr Sheila Strover on March 14, 2025

Tibial tuberosity transfer (TTT) includes a group of surgical procedures to improve the tracking of the patella in its underlying groove. Page updated June 2024 by Dr Sheila Strover (Clinical Editor)

tibial tubercle osteotomy

Surgery involves cutting the bony bump below the kneecap (the tibial tuberosity) and either moving it or re-angling it with a view to changing the forces through the patella.

Other names may be used for this group of procedures, ie tibial tubercle transfer or tibial tubercle osteotomy.

The rationale for tibial tuberosity transfer

The patella is at the mercy of the chain of structures that holds it in position in the groove of the femur.

This structure may experience extreme forces if the anatomy is abnormal, and the joint cartilage may become damaged, the patella painful, and subluxations and dislocations may occur.

When the patient is being investigated, the surgeon needs to evaluate:

In this paper we are talking about the third possibility, where poor tibial tuberosity alignment tugs on the patella during its tracking. Because in these procedures the corrective surgery is performed distal to the patella (below it) the various surgeries of tibial tuberosity transfer are lumped under the name of distal realignment procedures.

Several procedurs have been developed to move the tibial tuberosity, together with the patellar tendon, into a better mechanical position.

Peer-reviewed paper

  • Quote from a peer-reviewed paper:

    "Patellar instability can be caused by a multitude of factors, including MPFL injury, trochlear dysplasia, patella alta, and lateralization of the force vector. Each factor should be considered to have a variable contribution, and should be assessed as a potential contribution prior to considering surgery."

    Citation: Krishnan H, Eldridge JD, Clark D, Metcalfe AJ, Stevens JM, Mandalia V. Tibial tuberosity-trochlear groove distance: does it measure up? Bone Jt Open. 2022 Mar;3(3):268-274. doi: 10.1302/2633-1462.33.BJO-2021-0107. PMID: 35321559; PMCID: PMC8965791.

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Distal realignment procedures

Several distal realignment procedures have been developed to move the tibial tuberosity into a better position.

Although the concept seems simple, the number of procedures that have been developed reflect the difficulty in achieving a good outcome -

Peer-reviewed paper

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How does the TT-TG distance contribute to decision-making?

It is important for the surgeon to get an idea of the amount of sideways tug on the patella. This involves measuring the TT-TG distance or the distance in alignment between the tibial tubercle where the tendon attaches and the trochlear groove which constrains the patella.

The measurement is derived from a CT scan or MRI scan, where overlapping imaging views allows an estimate of how far out of alignment the tuberosity is. If it is more than 15-20mm it is considered significant, and tibial tubercle transfer may help to alleviate symptoms.

Peer-reviewed paper

  • Quote from peer-reviewed paper:

    "TT-TG is one guide to help determine the need for a medializing [tibial tubercle osteotomy], although its interpretation is complex and the high rates of subsequent patellofemoral OA in patients treated this way imply that it should be used with caution."

    Citation: Krishnan H, Eldridge JD, Clark D, Metcalfe AJ, Stevens JM, Mandalia V. Tibial tuberosity-trochlear groove distance: does it measure up? Bone Jt Open. 2022 Mar;3(3):268-274. doi: 10.1302/2633-1462.33.BJO-2021-0107. PMID: 35321559; PMCID: PMC8965791.

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