Patellar tendon attachment surgery

In patellar tendon attachment surgery, the attachment is moved on the tibia to change the direction of pull of the kneecap. Typically, it is moved downwards to bring a high riding kneecap down into the groove of the kneecap. It can also be moved inwards if it is too far outwards. 
Relocation of patellar tendon attachment because the attachment is too far out

Kneecap attachment surgery is occasionally used for patients with loose kneecap or anterior knee pain. If the kneecaps are stapled too far out on the shin, the direction of pull will be incorrect. This means that the kneecap is moving too far laterally. It may therefore be a good idea to undergo this type of surgery. How does the surgeon know if the attachment is too far lateral? Typically, you can measure something called TT-PCL distance on an MRI scan.  

Lars Blønd

Patient information leaflet tendon attachment transfer

Relocation of patellar tendon attachment because the kneecap is too high riding

If the kneecap is too high in relation to the groove (called patella alta), this surgery can pull the kneecap down into place in the groove (called a tuberosity tibia distalization). The surgeon can see on an MRI scan whether the overlap between the cartilage of the kneecap and the cartilage of the groove is in sufficient. If the kneecap sits too high, the overlap is too small (6 mm is less). 

The titanium screws are inserted at different angles to secure the patellar tendon attachment to the tibia after it has been displaced downwards due to an elevated patella.

Distalization of the tuberosity of the tibia (TTO distalization) which brings the kneecap down into the groove. The kneecaps attachment (Tibial tubercle) is moved downwards and fixed with 4 thin titanium screws. Called a tibial tubercle ostetomy – TTO

The kneecap is loose

If the kneecap attachment is moved because the kneecap is too loose, an  MPFL reconstruction is also performed. In addition, arthroscopic knee surgery is always performed (through a scope). A slightly different version of this surgery is called Fulkerson’s surgery and it can be used in a special subset of patients with anterior knee pain.

Anterior knee pain

Sometimes the patellar tendon attachment is moved because the kneecap is misaligned in its groove. This can cause pain, which is why surgery may be a good option. This type of surgery is often performed in combination with lateral retinaculum lengthening. You can read more here. A slightly different version of the patellofemoral tendon attachment surgery is called Fulkerson’s surgery and can be used in a special subgroup of patients with incipient osteoarthritis in the joint between the kneecap and the patella and with anterior knee pain.

Relocation of the patellar tendon attachment

Disadvantages of this option are as follows. Firstly, some small nerves that run across the scar in front of the patellar tendon attachment are cut. This causes altered sensation in the area. However, this can normalize over time. On the other hand, the screws that attach the patellar tendon attachment can sometimes interfere with kneeling. In the worst case scenario, the patellar tendon attachment does not heal. However, it is rare but can be seen in smokers.

A little science on the the subject

As shown in the image on the left, the patellar tendon attachment is chiseled off and moved further inwards. Screw the bone block back in place with 2 screws.

Complications of patellar tendon relocation

Unfortunately, not everyone that achived a good result from this type of surgery. If you have had surgery for a loose kneecap, unfortunately, some people find that the kneecap remains loose, and for those who have surgery for anterior knee pain, only 2 out of 3 are satisfied, although the results for those who have the patellar tendon attachment moved downwards due to a too high shell have a significantly higher success rate. Unfortunately, complications occur in a few percent of cases. There can be pain and sensory disturbances across the operated patellar tendon attachment, in some people the bone block doesn’t heal and some develop infection (I’ve never had the latter complication). Some people experience sensory disturbances across the patellar tendon attachment and some experience discomfort when kneeling – however, this is very rare if 4 small-headed screws are used instead of 2 large-headed screws.