Abstract：
Microfracture at the rotator cuff insertion is an established surgical marrow-stimulation technique for enhancing rotator cuff healing. However, the effect of lateralized or medialized microfracture on the insertion is unknown.
To compare the biomechanical and histologic effects of microfracture at 3 different regions for rotator cuff repair in a rat model.
Controlled laboratory study.
A total of 72 Sprague-Dawley rats with bilateral supraspinatus tendon insertion detachment were allocated into 4 groups with 4 different interventions: no microfracture at the humeral head as a control group (Con), traditional microfracture at the footprint area (MFA), and medialized microfracture to the footprint area (MMFA) on the articular surface of the humerus or lateralized microfracture to the footprint area at the greater tuberosity (LMFA). All underwent immediate repair. Tendon-to-bone healing was assessed by biomechanical and histologic tests 4 and 8 weeks postoperation.
At 4 weeks, the LMFA group showed a significantly superior failure load compared with the other groups (all P < .05). The LMFA and MFA groups showed significantly superior stiffness compared with the Con and MMFA groups (all P < .01). At 8 weeks, superior failure load and stiffness were observed in the LMFA group compared with the control group (all P < .05). Histologic examination revealed that the LMFA group had superior collagen composition and tendon-to-bone maturation at the interface at 4 and 8 weeks compared with the Con group (all P < .05).
Lateralized microfracture at the greater tuberosity improved the histologic quality of repair tissue and biomechanical strength at the tendon-to-bone insertion after rotator cuff repair in a rat model.
Microfracture lateral to the footprint area might be a better way to enhance rotator cuff healing clinically.
To compare the biomechanical and histologic effects of microfracture at 3 different regions for rotator cuff repair in a rat model.
Controlled laboratory study.
A total of 72 Sprague-Dawley rats with bilateral supraspinatus tendon insertion detachment were allocated into 4 groups with 4 different interventions: no microfracture at the humeral head as a control group (Con), traditional microfracture at the footprint area (MFA), and medialized microfracture to the footprint area (MMFA) on the articular surface of the humerus or lateralized microfracture to the footprint area at the greater tuberosity (LMFA). All underwent immediate repair. Tendon-to-bone healing was assessed by biomechanical and histologic tests 4 and 8 weeks postoperation.
At 4 weeks, the LMFA group showed a significantly superior failure load compared with the other groups (all P < .05). The LMFA and MFA groups showed significantly superior stiffness compared with the Con and MMFA groups (all P < .01). At 8 weeks, superior failure load and stiffness were observed in the LMFA group compared with the control group (all P < .05). Histologic examination revealed that the LMFA group had superior collagen composition and tendon-to-bone maturation at the interface at 4 and 8 weeks compared with the Con group (all P < .05).
Lateralized microfracture at the greater tuberosity improved the histologic quality of repair tissue and biomechanical strength at the tendon-to-bone insertion after rotator cuff repair in a rat model.
Microfracture lateral to the footprint area might be a better way to enhance rotator cuff healing clinically.
摘要：
■肩袖插入处的微骨折是一种已建立的用于增强肩袖愈合的手术骨髓刺激技术。然而,侧向或中等微骨折对插入的影响尚不清楚。
■在大鼠模型中比较3个不同区域的微骨折对肩袖修复的生物力学和组织学影响。
■对照实验室研究。
■将72只双侧冈上肌腱插入脱离的Sprague-Dawley大鼠分为4组，采用4种不同的干预措施：以肱骨头无微骨折为对照组（Con），足迹区域的传统微骨折(MFA)，和中等微骨折到肱骨关节表面的足迹区域（MMFA）或侧向微骨折到大结节（LMFA）的足迹区域。全部进行了立即修复。术后4周和8周通过生物力学和组织学测试评估肌腱至骨的愈合。
■4周时，与其他组相比，LMFA组显示出明显优于其他组（均P<0.05）。与Con和MMFA组相比，LMFA和MFA组显示出明显的硬度（所有P<0.01）。在8周的时候,与对照组相比，LMFA组的破坏载荷和刚度均优于对照组（均P<0.05）。组织学检查显示，与Con组相比，LMFA组在4周和8周时界面的胶原成分和腱-骨成熟均优于Con组（均P<0.05）。
■大结节侧化微骨折改善了大鼠模型肩袖修复后肌腱-骨插入处修复组织的组织学质量和生物力学强度。
■脚印区域外侧的微骨折可能是临床上增强肩袖愈合的更好方法。
■在大鼠模型中比较3个不同区域的微骨折对肩袖修复的生物力学和组织学影响。
■对照实验室研究。
■将72只双侧冈上肌腱插入脱离的Sprague-Dawley大鼠分为4组，采用4种不同的干预措施：以肱骨头无微骨折为对照组（Con），足迹区域的传统微骨折(MFA)，和中等微骨折到肱骨关节表面的足迹区域（MMFA）或侧向微骨折到大结节（LMFA）的足迹区域。全部进行了立即修复。术后4周和8周通过生物力学和组织学测试评估肌腱至骨的愈合。
■4周时，与其他组相比，LMFA组显示出明显优于其他组（均P<0.05）。与Con和MMFA组相比，LMFA和MFA组显示出明显的硬度（所有P<0.01）。在8周的时候,与对照组相比，LMFA组的破坏载荷和刚度均优于对照组（均P<0.05）。组织学检查显示，与Con组相比，LMFA组在4周和8周时界面的胶原成分和腱-骨成熟均优于Con组（均P<0.05）。
■大结节侧化微骨折改善了大鼠模型肩袖修复后肌腱-骨插入处修复组织的组织学质量和生物力学强度。
■脚印区域外侧的微骨折可能是临床上增强肩袖愈合的更好方法。
