Isolated MPFL reconstruction for recurrent lateral patellar instability in patients with TT-TG distance <25 mm: A calculated safe risk!

Objectives: The objectives of the study were to describe the surgical technique of our modification of isolated medial patellofemoral ligament (MPFL) reconstruction, in patients with patellar instability. As per literature, isolated MPFL reconstruction is advocated if tibial tubercle-trochlear groove (TTTG) <20 mm. Our study proposes isolated MPFL reconstruction in patients with TT-TG <25 mm and aims to determine any predisposing anatomic variants to aid in the treatment algorithm. Materials and Methods: A retrospective analysis of 52 patients with patellar instability (TT-TG <25 mm), who underwent isolated MPFL reconstruction was undertaken. The study population was divided into two groups; TT-TG <20 mm and TT-TG = 20–24 mm. Both groups were assessed radiologically and on the basis of clinical and functional outcome (KUJALA score), over 5-year follow-up period. Results: The mean age of the study population was 21.98 years, with a female (63.5%) majority. Among the 52 patients included in the study, 39 patients (75%) had TT-TG <20 mm and 13 patients (25%) had TT-TG = 20–24 mm. We noticed statistically significant improvement in both groups with respect to clinical and functional outcome, with no reported complications. None of the patients had patella alta or high grades of trochlear dysplasia. Conclusion: MPFL reconstruction without concomitant bony procedures can be safely performed in patients with a TT-TG <25 mm, in the absence of patella alta or high-grade trochlear dysplasia. Our modification of isolated MPFL reconstruction has shown excellent long-term results. In addition, our technique uses only a single interference screw, thereby reducing cost of surgery and implant hardware.

Der Tuberositas-Transfer im kindlichen Alter

ZusammenfassungDie patellofemorale Instabilität (PFI) ist eine typische Erkrankung im Kindes- und Jugendalter. Aufgrund des hohen Reluxationsrisikos ist eine gezielte Risikoanalyse notwendig. Die Patella alta und eine veränderte Zugrichtung des Streckapparates, die über den TTTG-Abstand ermittelt werden kann, stellen auch im jungen Alter Hauptrisikofaktoren der PFI dar. Die zunehmend evidenzbasierte Indikationsstellung unterscheidet sich nicht wesentlich von der Erwachsener. Aufgrund der Gefahr einer gestörten Wachstumslenkung kann bei offenen Fugen ein Tuberositas-Transfer jedoch nicht erfolgen, sodass die operativen Techniken den Gegebenheiten angepasst werden müssen. Eine Korrektur der Patella alta und eines erhöhten TTTG-Abstands ist mit weichteiligen distalen Eingriffen ohne Beeinträchtigung der Wachstumsfugen auch im Kindes- und Jugendalter möglich und verbessert die Ergebnisse gegenüber isolierten MPFL-Rekonstruktionen bei Überschreiten von Grenzwerten der Risikofaktoren und korrekter Indikationsstellung.

Patient-Reported Outcomes and Risk Factors for Decreased Improvement after Patellofemoral Arthroplasty

Patellofemoral arthroplasty (PFA) is acknowledged as the method for the treatment of isolated patellofemoral osteoarthritis (PFOA). Few previous studies have assessed the patient-reported outcomes (PROs) and risk factors of less improvement of PROs in patients undergoing PFA. A retrospective analysis was performed, including all patients who had undergone PFA. Pre- and postoperative PROs included the Oxford Knee Score (OKS) and Kujala score. Univariate and multivariate statistical analyses were performed to assess influencing factors of less improvement of PROs including the demographic factors (gender, age, body mass index, smoking, opioid usage, and duration of symptoms [DOSs]), surgical factors (concomitant surgery), and imaging factors (trochlear dysplasia [TD], patellar height, the degree of PFOA). A total of 46 PFAs were analyzed with a mean follow-up of 37 ± 7 months. The mean age at surgery was 61.1 ± 7.7 years. Patients showed significant improvement in all PROs (p < 0.001). Patients with TD preoperatively have greater improvement in OKS and Kujala score postoperatively (19.2 ± 5.0 vs. 23.1 ± 3.6, p = 0.038). Longer DOSs (≥1 year) had a greater mean improvement in OKS and Kujala score (p = 0.011 and p = 0.000). According to the measurement of patella height, patients with patella alta (Caton–Deschamps index [CDI] ≥1.3) showed less improvement in both OKS and Kujala score (p = 0.000 and p = 0.002). PFA is a safe and efficient surgery with good PROs. Patella alta with a CDI ≥1.3 and duration of preoperative symptoms ≤ 1 year were risk factors for decreased OKS and Kujala score improvement, while the preoperative presence of TD was significantly predictive factors for increased OKS improvement.