In patients who suffer from recurrent dislocation of the kneecap (patella) a common contributing factor is that the groove in the femur bone in which the kneecap glides is filled up with too much bone.

The groove is called the 'trochlear groove' and a trochleoplasty operation intends to create or deepen this groove to help to stabilise the patella.


This is what the National Institute of Heath and Care Excellence (N.I.C.E.) says:

"Patellar instability occurs when the patella fails to engage securely in the trochlea at the start of flexion; it slips laterally and either dislocates completely or slips back medially to its correct position as flexion continues....In some patients this happens because the trochlear groove is too shallow or uneven (trochlear dysplasia).


"Conservative treatment includes physiotherapy and exercises to strengthen the quadriceps. Surgical approaches include direct reconstruction of the dysplastic trochlea or correction of associated factors by procedures such as medial patellofemoral ligament reconstruction.


"Trochleoplasty aims to reshape the bony anatomy of the trochlea: it may involve deepening the groove or elevating the lateral wall of the trochlea (which should be higher than the medial). Trochleoplasty is usually done as an open procedure, which is associated with risks such as arthrofibrosis and rarely infection."


In plainer English, this means that a kneecap (patella) that fails to engage in the underlying groove can slip out to the outer side of the knee as the person begins to bend the knee. As the knee continues to bend, it can either slip back into the groove or dislocate completely over the edge. In some patients this instability is due to a structural abnormality in the groove underneath the patella - which is sometimes correctable by the procedure of 'trochleoplasty' (re-fashioning the groove).



arthroscopic trochleoplastyThe principle of trochleoplasty is to release the cartilage from the trochlea in order to be able to remove the excessive bone underneath it. Then the groove is deepened and the overlying cartilage is fixed back in place. The fixation is done by means of resorbable bands. From a mechanical point of view the trochleoplasty procedure is the most anatomical correct operation to perform, but the surgical method is still new and few surgeons master the technique.

Long-term results after trochleoplasty looks promising compared to other methods. In cooperation with the Panum Institute in Copenhagen and my German colleague Philip Schöttle, we have developed a technique where the trochleoplasty operation can be performed with an arthroscopic technique, that is via keyhole surgery. We call the procedure the 'arthroscopic deepening trochleoplasty' The technique is based on an arthroscopic shoulder technique, using instruments from shoulder surgery in the knee. The arthroscopic technique of trochleoplasty is less traumatic for the knee and causes less pain and smaller scars than the earlier procedures, together with a more rapid rehabilitation. We have performed arthroscopic trochleoplasty routinely since 2008 without any re-dislocation to date. Arthroscopic trochleoplasty is always performed in combination with MPFL reconstruction.


Here is a short educational video prepared with the help of the KNEEguru team, and which includes an explanation of the arthroscopic deepening trochleoplasty as well as footage of a live surgical procedure:


Our results have been published in peer reviewed journals1,2.

To date, I have also presented "The Arthroscopic Deepening Trochleoplasty" technique in the United States, Japan, Netherlands, UK, Sweden, Norway, and Poland.

Other reading:



  • 1. Blønd L. and Schöttle P. “The arthroscopic deepening trochleoplasty” Knee Surg Sports Traumatol Arthrosc 2010 Apr;18(4):480-5
  • 2. Blønd L., & Haugegaard M. Combined arthroscopic deepening trochleoplasty and reconstruction of the medial patellofemoral ligament for patients with recurrent patella dislocation and trochlear dysplasia. Knee Surg Sports Traumatol Arthrosc 2013 doi:10.1007/s00167-013-2422-2