The Relationship Between Supraspinatus Tendon Moment Arm Length, Shoulder Anatomical Features, and Shoulder Disorders

Abstract

This study aimed to evaluate the relationship between the moment arm length of the supraspinatus tendon and shoulder pathologies. The muscle-tendon moment arm represents the mechanical advantage of a muscle and significantly influences its role as a stabilizer or prime mover. In 83 patients, the presence of biceps tendinitis, rotator cuff tendinosis and tears, acromioclavicular joint degeneration, and footprint cysts were assessed. A perpendicular line was drawn from the center of the humeral head to the center of joint motion, and its length was measured (B). The distance from the rotator cuff footprint to the center of joint motion was also calculated (A). Subsequently, the ratio of these two lengths was determined (A/B). The mean moment arm length ratio (A/B) was 1.53 ± 0.11, the mean subacromial distance was 8.56 ± 1.35 mm, and the mean coracohumeral distance was 8.51 ± 1.51 mm. No significant correlation was identified between moment arm length and shoulder pathologies that could impact diagnosis, characterization, or treatment planning. A reduction in coracohumeral distance was associated with an increased incidence of tendinosis and tears in the subscapular tendon. Similarly, a decrease in subacromial distance correlated with a higher incidence of rotator cuff tears. Although moment arm length is important in surgical planning following tendon rupture, it does not serve as a diagnostic guide. The association between subacromial and coracohumeral distances and rotator cuff tendon tears may reflect a bidirectional relationship, where anatomical narrowing and tendon injury may influence each other.

Keywords

• Moment arm
• rotator cuff
• magnetic resonance

Ethical Statement

Ethical approval for the study was obtained from the Clinical Research Ethics Committee of Mersin University (approval number: 2023/729, dated 01.11.2023) prior to its initiation.

Supraspinatus Tendonunun Moment Kolu Uzunluğu ve Omuz Anatomik Özelliklerinin Omuz Patolojileri İle İlişkisi

Abstract

Bu çalışmanın amacı; supraspinatus tendonunun moment kolu uzunluğu ile omuz patolojileri arasındaki ilişkiyi değerlendirmektir. Kas-tendon moment kolu, bir kasın mekanik avantajını temsil eder ve dengeleyici veya ana taşıyıcı olarak rolünü büyük ölçüde belirler. Bu çalışmada, omuz Manyetik Rezonans görüntüleme kaydı bulunan 83 hastanın biseps ile rotator manşet kaslarının tendinozis ve yırtıkları, akromiyoklavikular eklemde dejenerasyon, kemik kisti gibi patolojiler araştırıldı. Humerus başının en geniş olduğu kesitte başın merkezi işaretlenerek eklem hareket merkezine dik bir çizgi çizilmiş ve bu uzunluk (B) ölçülmüştür. Rotator manşet ayak izinin eklem hareket merkezine uzaklığı (A) hesaplanmış ve ardından bu iki uzunluğun oranı (A/B) belirlenmiştir. Ayrıca, akromiyon sınıflandırılmış ve subakromiyal ile korakohumeral mesafeler ölçülmüştür. Elde edilen sonuçlara göre, moment kolu uzunluğu oranının (A/B) ortalaması 1,53 ± 0,11, subakromiyal mesafe ortalaması 8,56 ± 1,35 mm ve korakohumeral mesafe ortalaması 8,51 ± 1,51 mm olarak hesaplanmıştır. Moment kolu uzunluğu ile omuz çevresi patolojileri arasında tanımlayıcı, tanı ve tedavi sürecini etkileyebilecek anlamlı bir ilişki tespit edilmemiştir. Bununla birlikte, Tip 2 ve Tip 3 akromiyonların, Tip 1'e kıyasla daha dar bir subakromiyal mesafe oluşturduğu görülmüştür.Korakohumeral mesafe azaldıkça subskapular tendonda tendinozis ve yırtık görülme sıklığının arttığı, subakromiyal mesafenin azalması ile rotator manşet yırtıklarının görülme sıklığının arttığı belirlenmiştir. Sonuç olarak moment kolu uzunluğu, rüptür sonrası cerrahi onarımda önemli bir faktör olmasına rağmen, tanı için yol göstericiliği yoktur . Subakromiyal ve korakohumeral mesafeler ile rotator manşet tendon yırtıkları arasındaki ilişki, anatomik daralma ile tendon hasarının birbirini karşılıklı olarak etkileyebileceği çift yönlü bir ilişkiyi yansıtıyor olabilir.

Keywords

• Moment kolu
• rotator manşet
• manyetik rezonans

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