Turkish Version of the Norwich Patellar Instability Score: Minimal Detectable Change among Patients with Traumatic Patellar Dislocation

Abstract

Objective: This study aimed to calculate the minimal detectable change (MDC) in the Norwich Patellar Instability score (NPI) and validate the score for Turkish-speaking individuals with patellar instability. Method: Sixty-four patients (mean age 21.87 ± 9.44 years) who had experienced at least one patellar dislocation during athletic activities participated in the study. The Turkish version of the NPI (NPI-T) was evaluated for reliability and internal consistency. The Minimal Detectable Change was calculated as an overall value for the participants. MDC was calculated based on the standard error of measurement (SEM) and the selected confidence level (ICC) for the study population. Pearson's correlations were examined to assess construct validity between the Kujala Patellofemoral Disorder score and the Lysholm Knee Score. Result: The MDC for the NPI-T was 17.29, with a SEM of 6.24. The score demonstrated high internal consistency, with a Cronbach’s alpha value of 0.85, indicating substantial reliability. The consistency of measurements was excellent, with an ICC2,1 of 0.95. Additionally, the NPI-T score exhibited a strong negative correlation with both the Kujala (r = -0.85, p < 0.001) and Lysholm (r = -0.89, p < 0.001) scores. A floor effect was observed, but no ceiling effect was present. Conclusion: The study confirms that the NPI-T demonstrates strong psychometric properties, with high internal consistency and excellent reliability, as evidenced by its low MDC and SEM. The use of the NPI-T as a reliable and valid tool for assessing patellar instability in patients with patellar dislocation will provide valuable information to clinicians.

Keywords

• Patellofemoral instability
• Minimal detectable change
• Reliability
• Validity

Norwich Patellar İnstabilite Skorunun Türkçe Versiyonu: Travmatik Patellar Dislokasyonu Olan Hastalarda Minimal Tespit Edilebilen Değişiklik

Abstract

Amaç: Bu çalışmanın amacı, Norwich Patellar İnstabilite Skoru'nun (NPI) minimum tespit edilebilir değişikliğini (MDC) hesaplamak ve patellar instabilitesi olan Türkçe konuşan bireyler için skoru doğrulamaktır. Yöntem: Çalışmaya, spor aktiviteleri sırasında en az bir patella çıkığı yaşayan 64 hasta (ortalama yaş 21,87 ± 9,44 yıl) katılmıştır. NPI'nin Türkçe versiyonu (NPI-T) güvenilirlik ve iç tutarlılık açısından değerlendirilmiştir. MDC, katılımcılar için genel bir değer olarak, çalışma popülasyonu için standart ölçüm hatasına (SEM) ve seçilen güven düzeyine (sınıf içi korelasyon katsayısı, ICC) dayalı olarak hesaplanmıştır. Kujala Patellofemoral Bozukluk Skoru ile Lysholm Diz Skoru arasındaki yapı geçerliliğini değerlendirmek için Pearson korelasyonları incelenmiştir. Sonuçlar: NPI-T'nin MDC'si 17,29 ve SEM'i 6,24 olarak bulunmuştur. Skor, 0,85'lik Cronbach alfa değeriyle yüksek bir iç tutarlılık sergilemiş; bu da önemli bir güvenirliğe işaret etmektedir. Ölçümlerin tutarlılığı 0,95'lik ICC2,1 ile mükemmel seviyede bulunmuştur. Ek olarak, NPI-T puanı hem Kujala (r = -0,85, p < 0,001) hem de Lysholm (r = -0,89, p < 0,001) puanlarıyla güçlü bir negatif korelasyon göstermiştir. Zemin etkisi gözlenmiş ancak tavan etkisi mevcut olmamıştır. Sonuç: Çalışma, NPI-T'nin düşük MDC ve SEM ile yüksek iç tutarlılık ve mükemmel güvenilirliğe sahip olduğunu doğrulamaktadır. NPI-T'nin patellar dislokasyonu olan hastalarda patellar instabiliteyi değerlendirmede güvenilir ve geçerli bir araç olarak kullanılması, klinisyenlere değerli bilgiler sağlayacaktır.

Keywords

• Patellofemoral instabilite
• Minimal tespit edilebilir değişiklik
• Güvenilirlik
• Geçerlilik.

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