棒球投手肩旋轉肌腱等張運動之超音波應變分析

Abstract

肌腱的功能是負責將肌肉力量傳遞至骨骼以協助轉動，並將肌肉的力量加以儲存及釋放，使力量合適的輸出以避免受傷。肌腱的損傷可分為急性撕裂傷以及慢性撕裂傷或功能性退化損傷。急性撕裂傷是因為受到撞擊或過度拉伸所導致，患者通常會感到較多的疼痛，而慢性撕裂傷或是功能性退化撕裂則是因為長期微小的撕裂傷累積或功能性退化所導致，患者並不一定會感到疼痛。 棒球是一項劇烈的過頂投擲運動，投手在投球時肩關節會產生極大的扭力，而肩袖肌腱必須承受極大的牽引力以保護肩袖肌群，如此反覆的投球過程會對肩袖肌腱造成極大的負擔。據統計棒球選手的肩袖撕裂比率較一般人高，其中投手更是肩袖撕裂風險最高的族群。肩袖損傷不僅代表著投手在賽場上的表現降低亦代表著龐大的醫療費用以及休賽日增加甚至導致運動生涯結束，故預防肩袖撕裂變成一個重要的議題。在過去，由於技術上的限制以及對機械生物力學的不理解，投手經常在不適當的環境中進行投球訓練以及比賽。近年來，由於預防運動傷害的意識提升，對於投球數的控制以及休息時間的調適均有所改進。此外，在醫學技術以及機械生物力學上的進步，人們對於肌腱的解剖學以及疲勞機制有更深入的理解，在體內研究以及體外研究均得到良好的進展。有相關文獻認為肌腱的疲勞與肌腱的應變有所關聯。 在肌腱之體外研究中，雖較能控制實驗變因，但卻無法符合人體內的複雜性，為了更了解肌腱在體內的狀態，於體內之肌腱相關研究是必要的。在過去，常以骨標誌物或其他標誌物之間的距離做為肌腱之應變估計，然而這樣的分析並無法獲得更細微的肌腱資訊且在分析位置受限於標誌物。隨著超音波技術的提升，使得影像分析上不必侷限於明顯的特徵點。在肩袖撕裂的檢查中，超音波影像被認為與MRI影像有相同的準確度且在肌腱之應變分析上漸漸得到認可。更重要的是，有別於應力傳感器以及MRI影像，超音波具有低成本、便攜性、非侵入性以及實時成像的優勢，故在球場上以超音波對投手進行肩袖肌腱的狀態量測應具有一定的潛力。 本實驗使用B Mode動態超音波影像並以基於光流法之斑點追蹤對10名菁英現役投手之肩胛下肌肌腱以及棘上肌肌腱進行應變分析，並以NCORR做為分析結果之驗證工具。此外，為了瞭解投手之肩袖肌腱疲勞狀態是否會隨著賽季改變以及肩袖肌腱之內部特性，我們分別於賽季前(preseason)、賽季中(regular season)對肩胛下肌肌腱之應變狀態進行比較並且在賽季後(postseason)對棘上肌進行應變分析以探討棘上肌肌腱內部應變分布的情況。我們在等張運動中發現肩胛下肌之附著點的平均應變分別為賽季前8.82±2.69%以及賽季中18.69±3.07%，結果呈現成長趨勢。此外，在向心運動之棘上肌淺層、中層以及深層，分別得到18.77±3.13%的拉伸應變以及-9.27%±4.09%的收縮應變，以及在離心運動之棘上肌淺層、中層以及深層，分別得到19.07±2.50%和11.76±2.26%以及3.89±1.90%的拉伸應變結果，呈現肌腱之不均勻性。 最後，我們認為將光流法應用於肩胛下肌之超音波影像以及棘上肌之超音波影像中是具有潛力的，並於肩胛下肌腱發現賽季前以及賽季中之應變上的微顯著變化( (p<0.05)，儘管如此，我們仍需要更多的投手數據以及更長期的追蹤才能更了解肌腱之應變與疲勞之間的關係。而在棘上肌中，我們發現在離心運動以及向心運動中皆發現肌腱之不均勻性，我們認為這是棘上肌容易發生撕裂傷的原因之一。

The function of the tendon is to transmit the force of the muscle to the bones to assist in the rotation, and to store and release the force of the muscle so that the force can be output appropriately to avoid injury. Tendon injuries can be classified as acute lacerations as well as chronic lacerations or functionally degenerative injuries. Acute lacerations are caused by impact or overstretching and the patient usually experiences more pain, while chronic lacerations or functionally degenerated tears are caused by long-term accumulation of small lacerations or functional degeneration. As a result, the patient does not feel pain probably. Baseball is a strenuous overhead sport. The pitcher's shoulder joint will produce a lot of torsion when throwing the ball, and the rotator cuff tendon must bear great traction to protect the rotator cuff. The repeated pitching process can place a great burden on the rotator cuff tendons. According to statistics, baseball players have a higher rotator cuff tear rate than the ordinary person, and pitchers are the group with the highest risk of rotator cuff tear. Rotator cuff injuries not only represent a decrease in pitchers' performance on the field, but also represent huge medical expenses, increased offseasons and even athletic career termination. Therefore, preventing rotator cuff tears has become an important issue. In the past, due to technical limitations and a lack of understanding of mechanical biomechanics, pitchers OPTen practiced and played in inappropriate environments. In recent years, due to the increased awareness of sports injury prevention, the control of pitch count and the adjustment of rest time have improved. In addition, with advances in medical technology and mechanical biomechanics, people have a deeper understanding of tendon anatomy and fatigue mechanisms, and both in vivo and ex vivo studies have made good progress. There are related literatures that tendon fatigue is related to tendon strain. In the in vivo study of tendon, although it is better to control the experimental variables, it cannot meet the complexity of the human body. In order to better understand the state of tendon in vivo, in vivo tendon-related research is necessary. In the past, the distance between bone markers or other markers was OPTen used as the strain estimation of the tendon, however, such analysis could not obtain finer tendon information and was limited by the markers in the analysis location. With the improvement of ultrasonic technology, the image analysis need not be limited to obvious characteristic points. In the examination of rotator cuff tears, ultrasound imaging is considered to have the same accuracy as MRI imaging and is gradually accepted in the analysis of tendon strain. More importantly, unlike pressure transducer and MRI images, ultrasound has the advantages of low cost, portability, non-invasiveness and real-time imaging. Therefore, rotator cuff status measurements on pitchers with ultrasound should have some potential. In this experiment, B Mode dynamic ultrasound images and speckle tracking based on optical flow method were used to analyze the strain of the subscapularis and supraspinatus tendons of 10 elite active pitchers, and NCORR was used as a verification tool for the analysis results. In addition, in order to understand whether pitchers' rotator cuff fatigue status changes with season and the internal properties of the rotator cuff tendon, we compared the strain status of the subscapularis tendon in the preseason and in the regular season. In addition, the postseason strain analysis of the supraspinatus was performed to investigate the internal strain distribution of the supraspinatus tendon.We found that the average strain of the enthesis of the subscapularis in the isotonic exercise was 8.82±2.69% before the season and 18.69±3.07% in the season, respectively, and the results showed an increasing trend. In addition, in the superficial, middle and deep layers of the supraspinatus muscle during concentric contraction, tensile strains of 18.77±3.13% and contraction strains of -9.27%±4.09% were obtained, respectively, and in the superficial and middle layers of the supraspinatus muscle during eccentric contraction and deep layers, tensile strain results of 19.07±2.50% and 11.76±2.26% and 3.89±1.90% were obtained, respectively, showing the inhomogeneity of tendon. Finally, we believe that the optical flow method has the potential to be applied to the ultrasound elastography of the subscapularis and the supraspinatus, and to detect slightly significant changes in pre-season and in-season strain in the subscapularis tendon ((p<0.05), however, we still need more pitcher data and longer-term follow-up to better understand the relationship between tendon strain and fatigue. In addition,we found inhomogeneous tendon strain in the eccentric contraction of the supraspinatus as well as in the concentric contraction, which we believe is one of the reasons why the supraspinatus is prone to ruptures.