Good outcomes seen at midterm follow-up after isolated MPFL reconstruction

Overall, good outcomes were seen after isolated medial patellofemoral ligament reconstruction at midterm follow-up, according to recently published results. However, patients with a high preoperative patellar tilt, small correction in tilt and those who had femoral tunnel malpositioning saw less improvement in clinical outcomes.

Perspective from Jacqueline M. Brady, MD

Researchers identified 107 patients who underwent isolated medial patellofemoral ligament reconstruction. The mean follow-up was 59 months. Preoperatively and every 12 months, the functional IKDC and Kujala scores were assessed. Preoperatively and at 6 months, radiological assessment of patellar height and tilt was performed, as well as CT scan measurement of patellar tilt and tibial tubercle-trochlear groove distance. Investigators used Schöttle’s criteria to assess femoral tunnel position. A 3-D CT scan was used at 6 months to measure the amount of femoral tunnel widening. Univariate and multivariate regression analyses were used to determine clinical and radiological predictors preoperatively and postoperatively.

Results showed a significant improvement in IKDC and Kujala functional scores from preoperative to postoperative measures. Functional scores were not affected by demographics, dislocation characteristics, clinical data and complications. Small correction of the patellar tilt reported on the CT scan measurement, malpositioning of the femoral tunnel and widening of the tunnel near the medial cortex were among predictors of a lower improvement in functional scores. There was a correlation between tunnel widening, patients with anterior and proximal malpositioning who had stiffness in flexion and malpositioning of the femoral tunnel. – by Monica Jaramillo

Disclosures: The authors report no relevant financial disclosures.

Perspective

Jacqueline M. Brady, MD

Neri and colleagues undertook an elegant study to predict outcomes of isolated MPFL reconstruction. One variable that predicted improved outcomes was increased preoperative patellar tilt, though no patients underwent any lateral retinacular release or lengthening. Postoperative tilt did not prove significant, but a large change in tilt predicted improved scores. Importantly, the authors did not include patellar subluxation or factors thought to contribute to tilt — trochlear dysplasia (if any), patellar height or TT-TG distance — in their analysis.

Unsurprisingly, femoral tunnel malposition was a negative predictor of functional outcome. Another negative predictor was widening of the femoral tunnel on postoperative CT scan. The authors theorize that this reflects an excess of graft tension, and therefore over-constraint of the patellofemoral joint.

The opposite effects of patellar tilt correction and femoral tunnel widening are an important demonstration of the difficult balance that must be struck when setting the tension on the MPFL graft. If too loose, the graft may fail to prevent lateral patellar translation and maltracking. If too tight or anisometric, it may cause over-constraint and potentially osteoarthritis. This study highlights the careful attention to graft position and tension that is necessary in order to optimize outcomes of isolated MPFL reconstruction.

Jacqueline M. Brady, MD

Assistant professor of orthopedics and rehabilitation

School of Medicine

Oregon Health and Science University

Portland, Oregon

Disclosures: Brady reports no relevant financial disclosures.

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Source:

Neri T, et al. Am J Sports Med. 2019;doi:10.1177/0363546519831294 .