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Outcomes for Primary versus Revision Medial Patellofemoral Ligament Reconstruction with Concomitant Tibial Tubercle Osteotomy

Outcomes for Primary versus Revision Medial Patellofemoral Ligament Reconstruction with Concomitant Tibial Tubercle Osteotomy

Elizabeth Rose Dennis, MD MS, UNITED STATES William A. Marmor, MD, UNITED STATES Simone Gruber, MS, UNITED STATES Joseph T. Nguyen, MPH, UNITED STATES Beth Ellen Shubin Stein, MD, UNITED STATES

HOSPITAL FOR SPECIAL SURGERY, NEW YORK, NY- NEW YORK, UNITED STATES


2021 Congress   ePoster Presentation     Not yet rated

 

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Summary: This study compares patients who underwent primary MPFL+TTO versus those who underwent revision MPFL+TTO and reports on their demographic, radiographic, patient reported outcomes at baseline, 1-year and 2-years, return to sport rates and recurrent instability events.


Introduction

It is not currently understood which subset of patients with recurrent patellofemoral instability require concomitant bony realignment procedures in addition to a soft tissue stabilization. Additionally, the optimal timing of surgical intervention is not well defined by current literature and can be dictated by the skeletal maturity of a patient. If the patient’s complete pathology is not addressed at their primary procedure, there can be a high risk of recurrent instability necessitating revision surgery. It is not known if the outcomes of medial patellofemoral reconstruction with concomitant tibial tubercle osteotomy (MPFL+TTO) performed as a revision procedure equate the outcomes of MPFL+TTO performed in the primary setting. This study compares patients who underwent primary MPFL+TTO versus those who underwent the same procedure in the revision setting.

Methods

Patients who underwent a MPFL+TTO from March 2014 to December 2018 were identified from an institutional patellofemoral registry. Patients were separated into two groups, those undergoing a primary MPFL+TTO and those undergoing a MPFL+TTO after a previously failed surgical attempt for patellar stabilization. Baseline demographic, radiographic, and knee-specific patient reported outcome measures (PROMs) including KOOS QOL, Pedi-Fabs, IKDC, KOOS-PS, and Kujala were collected prior to surgery and at 1- and 2-years following surgical intervention. Return to sport (RTS) rates and recurrent instability events were also collected. Radiographic measurements included the Caton-Dechamps Index (CDI), Patellar Trochlear Index (PTI)1, Tibial Tubercle-Trochlear Groove (TT-TG), Tibial Tubercle-Lateral Trochlear Ridge (TT-LTR)2, Patellar Tendon-Lateral Trochlear Ridge (PT-LTR)3 and the Trochlear Depth Index (TDI)

Results

92 knees (84 patients) were included; 59 in the primary group and 33 in the revision group. No differences were identified between the groups with respect to sex (85% vs. 82%, p=0.715), age (23.7 vs. 22.5, p=0.468), BMI (26.3 vs 24.5, p=0.144), TT-TG (20.3 vs 19.3, p=0.238), or patella alta (33% vs 19%, p=0.354). Previous procedures in the revision cohort included 12 MPFL reconstructions, 3 tibial tubercle transfers, 16 lateral releases, 9 imbrications/reefings/plications, 7 loose body removals and 9 chondroplasties.

53 (90%) patients in the primary group and 29 (88%) patients in the revision group had a minimum of 2-year follow-up. There was no difference between the groups for recurrent dislocation (4% vs 0%, p=0.547), recurrent subluxation (9% vs 0%, p=0.162) and RTS (88% vs 83%, p=0.713). In regard to RTS, 79% of the primary surgery group and 71% of the revision group returned at an equal or higher level (p=0.461). At baseline, the primary group had a higher IKDC (42.0 vs 34.7, p=0.049).

At 2-year follow-up both groups had significant improvements from baseline in all PROMs, except Pedi-FABS which had no change. There was no difference between groups at 2-year follow-up in KOOS-QoL (60.8 vs 51.1, p=0.186), Pedi-FABS (8.0 vs 7.3, p=0.796), IKDC (75.2 vs 67.7, p=0.206), KOOS-PS (15.8 vs 20.9, p=0.379), and Kujala (86.5 vs 77.9, p=0.143).

The mean TT-TG, CDI, PTI and presence of patella alta was similar between groups. Trochlear dysplasia, defined as a TDI < 3 mm, was present in 77% of patients in both groups. The measure of extensor mechanism containment, TT-LTR, was similar between groups and the rate of TT-LTR within 1 mm, found to be predictive of recurrent instability, was 18% in the primary group and 26% in the revision group. PT-LTR, a measurement of lateral patellar tracking, was statistically significantly higher in the primary group (11.9 vs 8.7, p=0.045).

Discussion And Conclusion

Management of patellofemoral instability is complex. The optimal timing of surgical intervention and whether a concomitant bony realignment procedure is indicated has yet to be elucidated. This study demonstrates that primary MPFL+TTO versus revision MPFL+TTO have comparable objective and subjective outcomes at short term follow-up. Ongoing data collection for this patient cohort will determine whether these results are sustained at long term follow-up.