旋轉肌群破損影響相當多有年紀的病人，造成日常活動中的軟弱無力、功能障礙及一再發生的疼痛。由於棘上肌的解剖位置，導致該棘上肌特別容易在肌腱嵌入骨頭處破損，此處亦是分析指示高張應力與高壓應力處，且與臨床發現旋轉肌群經常發生破損處相關。雖然，旋轉肌群破損修復方法顯著地精進，為達最高可能的初始固定強度，然而，報告指出旋轉肌群破損修復後再次破損率仍高居不下，表明旋轉肌群癒合受到機械與生物因子組合的影響。旋轉肌群癒合關鍵性地決定臨床結果。目前，旋轉肌群破損修復後，在肌腱-骨頭介面多生成纖維血管性瘢痕組織，而非生成重要的原正常的纖維軟骨組織。過去研究指示，磷酸鈣(CaP)對於肌腱-骨頭介面癒合有助於新的骨頭生成、增加纖維軟骨形成及促進膠原蛋白組織等，且血小板濃縮液(PRP)內含癒合過程中需要的豐富生長因子與細胞激素，故而，本研究目的為探討磷酸鈣與血小板濃縮液對急性旋轉肌群破損修復癒合的影響。本研究假說為在急性旋轉肌群破損修復期間，磷酸鈣和血小板濃縮液的介入可改變生成纖維血管性瘢痕組織為生成纖維軟骨組織，增強肌腱-骨頭癒合。

總共六十四隻雄性Sprague-Dawley大鼠隨機分為兩批：(1)正常控制(N = 10)，(2)手術介入(N = 54)。在正常控制批裡，沒有任何手術介入。其中，四隻大鼠用於定量PRP的製備過程，另外六隻大鼠用於製備CaP + PRP合成物。在手術介入批裡，五十四隻大鼠等分為三組：(1)無材料於缺陷處之控制組(Ctl組)，(2)填補磷酸鈣實驗組(CaP組)，(3)填補磷酸鈣及血小板濃縮液實驗組(CaP + PRP組)。所有組別中，每隻大鼠的兩隻肩膀都手術建立急性棘上肌破損模型，雙側棘上肌立即接受穿骨修復與相同的組別治療。在術後二週、四週和八週，棘上肌肌腱嵌入骨頭癒合處進行維度測量以評估橫截面積，生物力學測試以評估極限負荷、剛度、極限應力及失敗模式，組織學評估總體形態、膠原蛋白組織、附著處重建及新的纖維軟骨形成，及微觀電腦斷層掃描分析評估骨分佈、BMD、BV / TV及TbTh。

維度測量結果顯示，術後二週、四週及八週，3組間棘上肌肌腱嵌入骨頭癒合處之截面積無統計上差異。生物力學測試結果顯示，在術後四週，CaP + PRP組棘上肌肌腱嵌入骨頭癒合處之剛度統計上明顯大於Ctl控制組(P = 0.049)。在術後八週，CaP + PRP組棘上肌肌腱嵌入骨頭癒合處之極限負荷統計上明顯大於Ctl控制組(P = 0.015)。不論在任何時間點，CaP和CaP + PRP組間棘上肌肌腱嵌入骨頭癒合處之極限載荷、剛度及極限應力均無統計上差異。組織學結果顯示，棘上肌肌腱嵌入骨頭癒合處的整體形態在癒合期間逐漸成熟、連續與重整，此現象在CaP和CaP + PRP組別尤為明顯。此外，相較於術後二週，術後八週注意到規則結締組織與其癒合至骨頭。微觀CT分析結果顯示，除了在術後二週CaP + PRP組棘上肌肌腱嵌入骨頭癒合處之TbTh相較於Ctl控制組無統計上差異外，在術後二~八週，CaP和CaP + PRP組棘上肌肌腱嵌入骨頭癒合處之BMD、BV / TV及TbTh統計上均明顯大於Ctl控制組。本研究結論，在旋轉肌群修復期間，磷酸鈣和血小板濃縮液的介入可以增強肌腱-骨頭癒合且幫助改變目前生成纖維血管性瘢痕組織為生成纖維軟骨組織。

Rotator cuff tear affect a substantial number of patients as they age and lead to weakness, dysfunction and re-current pain during daily activities. By virtue of its anatomic location, the supraspinatus is particularly vulnerable to tear at the tendon-bone insertion site where high tensile and compressive stresses were noted analytically and correlated with clinical finding of frequent occurrence of rotator cuff tears at this site. Despite significant advances in repair methods to achieve the highest possible initial strength, re-tear rates after rotator cuff repair are commonly reported to be high, indicating rotator cuff healing is influenced by a combination of mechanical and biological factors and is critical for clinical outcomes. However, the current nature of tendon-bone healing after rotator cuff repair is still the formation of fibrovascular scar tissue at the tendon-bone interface rather than the formation of fibrocartilage which is the crucial structure in native tendon insertion. With previous evidences shown the positive effects of calcium phosphate (CaP) in new bone formation, increased fibrocartilage, and improved collagen organization at the healing tendon-bone interface and abundant growth factors and cytokines involved platelet-rich plasma (PRP) in healing process, the purpose of this research is to evaluate the effect of CaP and PRP on tendon-bone healing for acute rotator cuff tear repairing. The hypothesis of this research is that the incorporation of CaP and PRP materials during acute rotator cuff repair could enhance tendon-bone healing by changing the fibrovascular scar tissue formation into fibrocartilage formation.

A total of sixty-four male Sprague-Dawley rats were randomly allocated into two sets: (1) normal control (N=10), (2) surgical intervened (N=54). In the normal control set, no any surgical intervene was applied on them. Four of them were used to quantify the PRP preparation process, while the other six rats were used to prepare the CaP + PRP compound. In the surgical intervened set, fifty-four rats were equally allocated into3 groups: (1) control group without material applied on defect (Ctl group), (2) experiment group with CaP applied on defect (CaP group), and (3) experiment group with CaP and PRP applied on the defect (CaP + PRP group). Both shoulders of each rat in all groups were underwent acute transaction and immediately received and transosseous repair and treatment on the bilateral supraspinatus tendon. At 2, 4, and 8 weeks post-operatively, the supraspinatus tendon-bone healing enthesis was underwent dimensional measurement to evaluate cross-sectional area, biomechanical testing to evaluate ultimate load, stiffness, ultimate stress, and failure mode, histological assessment to evaluate overall morphology, collagen organization, footprint regeneration and new fibrocartilage formation, and micro-computed tomography analysis to evaluate bone distribution, BMD, BV/TV, and TbTh.

Dimensional measurement indicated that no statistical differences in the cross-sectional area of the SS tendon-bone healing enthesis were found between the 3 groups at 2, 4, and 8 weeks postoperatively. Biomechanical testing indicated that there was significantly greater stiffness of the SS tendon-bone healing enthesis in the CaP + PRP group compared with the Ctl control at 4 weeks postoperatively (P = .049). At 8 weeks postoperatively, there was significantly greater ultimate load of the SS tendon-bone healing enthesis in the CaP + PRP group compared with the Ctl control (P = .015). No significant differences in ultimate load, stiffness, and ultimate stress were found between the CaP and CaP + PRP groups at any time points. Histological assessment indicated that the overall morphology of SS tendon-bone healing enthesis became progressively matured, continuous, and re-organized during healing periods, which was particularly obvious in the CaP and CaP + PRP groups. Moreover, regular connective tissue and its healing to the bone were noticed at 8 weeks postoperatively compared with at 2 weeks postoperatively. Micro-CT analysis indicated that there was significantly greater BMD, BV/TV, and TbTh of the SS tendon-bone healing enthesis in the CaP and CaP + PRP groups compared with the Ctl control from 2 to 8 weeks postoperatively except the TbTh between the CaP + PRP group and Ctl control at 2 weeks postoperatively. We concluded that the CaP plus PRP can enhance tendon-bone healing and aid in changing its current nature of fibrovascular scar tissue formation into fibrocartilage formation in rotator cuff tendon repair.

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