Patellofemoral Update focuses on the causes, prevention and treatment of patellofemoral disorders. The blog is sponsored by The Patellofemoral Foundation whose mission is to improve the care of individuals with anterior knee pain through targeted education and research. The Patellofemoral Foundation offers additional online education resources on its website.

BLOG: Surgical treatment of patella instability in perspective

by John P. Fulkerson, MD

Erickson and colleagues published an article in the May 2019 issue of the American Journal of Sports Medicine entitled, “Isolated medial patellofemoral ligament reconstruction for patellar instability regardless of tibial tubercle-trochlear groove distance and patellar height: Outcomes at 1 and 2 years.”

Beth Shubin Stein, MD, presented these results at the 2019 American Orthopedic Society of Sports Medicine Annual Meeting in Boston. Meanwhile, at the same meeting, David Diduch, MD, presented his successful 1-year results using trochleoplasty (all had MPFL reconstruction also) for treatment of recurrent patella dislocations. Fifty percent of the patients treated with trochleoplasty were revisions of earlier unsuccessful surgery and 20% of all the patients treated by trochleoplasty developed arthrofibrosis. Seth L. Sherman, MD, presented another paper at this meeting showing that tibial tubercle transfer, when needed in the treatment of recurrent patella instability, adds no significant morbidity. Those treated in the Erickson and Shubin Stein study had very low morbidity and no redislocations at 2 years.

It is important to note that the patients treated in Diduch’s study had more serious structural dysplasia and Diduch emphasized in his presentation the jumping J sign. In other words, a patella that is visually and structurally impaired by a very prominent supratrochlear spur causing the patella to jump laterally in extension. This is not so common in most orthopedic sports medicine practices but requires trochleoplasty. Such patients likely comprise less than 5% of patella instability patients seen in an average sports medicine practice.

The take-home messages I received are the following:

  • MPFL reconstruction works well for treatment of recurrent patella instability, so one must have a good reason to add anything more;
  • Tibial tubercle transfer, when needed, adds little risk and is important to unload lateral articular lesion(s) or establish balanced tracking and minimize risk of future arthritis; and
  • Trochleoplasty, when accompanied by MPFL reconstruction, is effective treatment for recurrent patella instability but has a 20% risk of arthrofibrosis and should be reserved for revision surgery and patients with a prominent “jumping J” sign. Also, it is a difficult surgery to do well that alters articular cartilage and subchondral bone with unknown long-term consequences. These patients should probably be referred to an expert skilled in this procedure.



Erickson BJ, et al. Am J Sports Med. 2019;doi:10.1177/0363546519835800.


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John P. Fulkerson, MD, is a clinical professor of orthopedic surgery at the University of Connecticut School of Medicine and practices at Orthopedic Associates of Hartford in Farmington, Conn. He is also president of The Patellofemoral Foundation.


Disclosure: Fulkerson reports he receives royalties from DJO Global and is a patent holder for DJO Global.

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