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MPFL reconstruction yielded low redislocation, instability rates at early follow-up
Isolated medial patellofemoral ligament reconstruction may be an effective treatment for patellar instability at early follow-up of 1 year and 2 years, according to recently published results. Regardless of bony pathologies, researchers noted that the reconstruction offers significant improvements in outcome scores and low redislocation and instability rates.
“[Isolated], technically well-done medial patellofemoral ligament [MPFL] reconstruction is an effective procedure to treat patellofemoral instability in the short term, regardless of bony pathology (tibial tubercle trochlear groove [TT-TG] distance, Caton-Deschamps index and trochlear dysplasia),” Brandon J. Erickson, MD, told Healio.com/Orthopedics. “Also, patients were able to return to sport at a high rate (90%), with a low rate of recurrent patellofemoral instability, and saw significant improvements in clinical outcome scores. The reason this is an important finding is an isolated MPFL reconstruction is less morbid than adding in a tibial tubercle osteotomy, so if we can achieve the same results in regard to stability, clinical outcomes and return-to-sport rate with a less morbid procedure, that is ideal.”
Researchers identified patients with recurrent patellar instability without significant unloadable chondral defects, cartilage defects, previous failed surgery or pain who underwent MPFL reconstruction. At 1 year and at 2 years, recorded information included recurrent subjective instability, dislocations, ability to return to sport and outcome scores. Investigators measured TT-TG distance, patellar height with the Caton-Deschamps index and the trochlear depth. There were 90 patients who reached the 1-year follow-up and the 47 patients reached the 2-year follow-up.
Results showed the mean TT-TG distance was 14.7 mm. The mean patellar height and mean trochlear depth were 1.2 mm and 1.8 mm, respectively.
There were 96% of patients at 1 year and 100% of patients at 2 years who did not have self-reported patellofemoral instability. At 3.5 years, one patient had a redislocation. At 1-year, the return-to-sport rate was 90% and was 88% at 2 years. Investigators noted the mean time to return to sport was 8.8 months.
Clinically and statistically significant improvement was seen in all patients for mean KOOS–quality of life, mean IKDC subjective form and mean Kujala scores. Outcome scores were no different between the 1-year and 2-year follow-ups.
“[We] will be following these patients long term to see if the results withstand the test of time,” Erickson said. “We are optimistic that they will, but [we] need to provide long-term evidence on this procedure.” – by Monica Jaramillo
Disclosures: Erickson reports he receives education payments from Smith & Nephew and education and hospitality payments from DePuy. Please see the full study for a list of all other authors’ relevant financial disclosures.
Perspective
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The surgeons at Hospital for Special Surgery have tackled a very important topic in this cohort outcome study. Many of the risk factors for patellar instability and the recurrence of patellar instability are well-known, however the thresholds at which these pathoanatomic risk factors should be addressed surgically continue to lack high-quality evidence.
These authors assessed 90 patients with recurrent patellar instability and performed an isolated MPFL reconstruction without concurrently correcting for TT-TG, patella alta or trochlear dysplasia. The study reports good clinical results with regard to re-dislocation, return-to-sport and patient-reported outcome measures. With this study, these authors have confirmed that for the vast majority of patients, an isolated MPFL reconstruction provides excellent results even in the presence of pathoanatomic risk factors.
One challenge of this study is that it is not known if the included patients may have had superior results with the addition of a bony procedure to address pathoanatomic features, such as an elevated TT-TG distance, patella alta or trochlear dysplasia. It would be interesting to know if there were any differences in outcomes comparing the patients with the traditional cut-off values for consideration of a concurrent bony procedure (TT-TG > 20 mm or a Caton-Deschamps > 1.2, type D trochlear dysplasia), compared to those patients with measures below these values. This is a very important study, and a randomized clinical trial would be an important next step to determine the necessity of adding a bony procedure in this complex patient population.
Banff Sport Medicine
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Erickson BJ, et al. Am J Sports Med. 2019;doi:10.1177/0363546519835800.