BLOG: Patellar instability remains an issue in modern total knee replacement

Patellar instability remains a challenging issue in modern total knee replacement patients. Total knee replacement has consistently been shown as a highly successful treatment for degenerative arthritis of the knee, but 33% to 50% of revision surgeries for this procedure in the 2-year to 5-year postoperative period have been attributed to patellar instability. In addition, patellar positioning in postoperative TKR patients shows up to a 15% chance of more than 5 mm of lateral patellar displacement from the trochlear groove.

In order to perform a total knee replacement (TKR), most surgeons perform a medial para-patellar arthrotomy that sacrifices the medial patellofemoral ligament (MPFL) to achieve an adequate surgical exposure. As we know, the MPFL serves as a static restraint to lateral patellar subluxation in the native knee.

Therefore, our hypothesis was to examine whether routine anatomic MPFL repair via a direct suture repair technique prior to arthrotomy closure in TKR patients prevented excessive mediolateral patellar translation.

James Bicos

Despite a small trend of greater preoperative tilt in these patients, out of 46 patients categorized into either a standard closure group (n=29) or an MPFL closure group (n=17), patients undergoing TKR with reconstitution (i.e., repair) of the MPFL prior to arthrotomy closure demonstrated a significantly smaller degree of postoperative lateral patellar tilt and subluxation at 4 months postoperatively compared with patients who had a standard arthrotomy closure.

As we continue to examine and research the anatomy of patellofemoral articulation, we consistently see the need for thoughtful anatomic repair of the structures we tend to violate during surgical dissections. This article shows the need for anatomic repair of all the structures of a medial patellar arthrotomy including the MPFL.

Reference:

Meneghini RM, et al. Surg Technol Int. 2015;27:275-278.

James Bicos, MD, is an assistant professor at Oakland University William Beaumont School of Medicine and the associate director of the William Beaumont Sports Medicine Fellowship. He also is an orthopedic surgeon and sports medicine specialist at Performance Orthopedics. He can be reached at 24255 Thirteen Mile Rd., Suite 100; Bingham Farms, MI 48025; email: jbicos@yahoo.com.

Disclosure: Bicos is a paid consultant for Bellevue Pharmacy and Biomet, and receives IP royalties from Innomed.