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Editorial Commentary: Repairing Retracted Rotator Cuff Tears: Histologically Different, but Success Still Achievable With “Failure in Continuity”

      Abstract

      Failure after rotator cuff repair continues to occur despite advances in our understanding of the native tendon enthesis. Recurrent postoperative tendon defects are common, and the impact of nonhealing on postoperative outcomes remains controversial. Rotator cuff tears (RCT) of all patterns commonly present with some degree of retraction, and it is, therefore, critical to understand and examine the biology and biomechanics of the retracted RCT to address why a repaired tendon may fail. An article in this issue reports on retracted tears forming more disorganized fibrous tissue with similar biomechanical properties compared to nonretracted tear tissue. It provides insight into what lies “beneath the surface” after retracted rotator cuff repair, but it is unclear whether the fibrous tissue formed after their acute partial tendon excision adequately reflects the tissue found in more chronic, retracted human rotator cuff tears, particularly with varying degrees of retraction. Facilitating a more favorable “scar-forming” environment and optimizing this postoperative fibrous tissue may be crucial to improving rotator cuff repairs in the future.
      More than a century after Codman’s visionary 1911 article reporting successful surgical repair of rotator cuff tears,
      • Codman E.A.
      Complete rupture of the supraspinatus tendon. Operative treatment with report of two successful cases. 1911.
      the ideal management still remains a significant source of controversy today. Initially treated via an open procedure, arthroscopic techniques involving suture anchors have revolutionized treatment, allowing surgeons to minimize surgical site morbidity, reduce postoperative pain, and accelerate patient recovery while reconstituting the native rotator cuff tendon insertion, or at least so we thought. Despite these advancements in surgical treatment, postoperative failure after primary and revision rotator cuff repair (RCR) continues to occur at an alarming rate, with tendon defects reported in 10-70% of RCRs in the contemporary literature.
      • McCarron J.A.
      • Derwin K.A.
      • Bey M.J.
      • et al.
      Failure with continuity in rotator cuff repair “healing.
      The definition and implications of postoperative failure have vacillated, as patients have often reported high rates of satisfaction despite radiographic evidence of tendon discontinuity or overt tendon retear.
      • Galatz L.M.
      • Ball C.M.
      • Teefey S.A.
      • Middleton W.D.
      • Yamaguchi K.
      The outcome and repair integrity of completely arthroscopically repaired large and massive rotator cuff tears.
      ,
      • Mellado J.M.
      • Calmet J.
      • Olona M.
      • et al.
      Surgically repaired massive rotator cuff tears: MRI of tendon integrity, muscle fatty degeneration, and muscle atrophy correlated with intraoperative and clinical findings.
      Questions of the “how, when, and why” this occurs have generally revolved around mechanical, biological, and patient-based factors affecting healing, alongside varying rehabilitation guidelines. With the inconclusive benefits of biologic adjuncts, our priorities during RCR have shifted to tear pattern recognition, soft tissue mobilization, and anatomic reduction while minimizing repair tension, particularly in the presence of tear retraction or increased chronicity.
      The limited innate regenerative healing capacity of native tendon is well documented.
      • Galatz L.M.
      • Gerstenfeld L.
      • Heber-Katz E.
      • Rodeo S.A.
      Tendon regeneration and scar formation: The concept of scarless healing.
      The mechanical stability provided with modern RCR techniques has still done little to improve this innate healing potential. Compounding this problem, rotator cuff tears, irrespective of tear pattern, commonly present with a modest degree of medial retraction, with an average displacement of 1.2 cm.
      • Sallay P.I.
      • Hunker P.J.
      • Lim J.K.
      Frequency of various tear patterns in full-thickness tears of the rotator cuff.
      Accordingly, it is critical to examine the healing environment of the retracted rotator cuff tear. While prior studies have shown well-organized fibrovascular tissue at the site of tendon-to-bone healing in the nonretracted, in situ rotator cuff injury,
      • Mannava S.
      • Plate J.F.
      • Tuohy C.J.
      • et al.
      The science of rotator cuff tears: translating animal models to clinical recommendations using simulation analysis.
      • Galatz L.M.
      • Sandell L.J.
      • Rothermich S.Y.
      • et al.
      Characteristics of the rat supraspinatus tendon during tendon-to-bone healing after acute injury.
      • Rodeo S.A.
      • Potter H.G.
      • Kawamura S.
      • Turner A.S.
      • Kim H.J.
      • Atkinson B.L.
      Biologic augmentation of rotator cuff tendon-healing with use of a mixture of osteoinductive growth factors.
      the histological and biomechanical changes of rotator cuff tendon tears under relative tension are not well described. Often termed “failure in continuity,” medial retraction of repaired tendons with interposed fibrotic tissue may result, potentially leading to suboptimal clinical outcomes.
      In “Retracted Rotator Cuff Repairs Heal with Disorganized Fibrogenesis Without Affecting Biomechanical Properties: A Comparative Animal Model Study”
      • Rhee S.M.
      • Youn S.M.
      • Ko Y.W.
      • Kwon T.Y.
      • Park Y.K.
      • Rhee Y.G.
      Retracted rotator cuff repairs heal with disorganized fibrogenesis without affecting biomechanical properties: A comparative animal model study.
      , Youn, Ko, Kwon, Park, and Rhee are to be commended for developing a well-designed, comparative small animal model to assess the histological and biomechanical differences between nonretracted and retracted cuff tears. Nonretracted cuff tear specimens received a 1-cm incision to the rotator cuff tendons over the footprint and were repaired in a classic transosseous manner, while retracted cuff tear specimens had a 1×1 cm tendinous portion of cuff excised prior to repair. The authors compared collagen fiber orientation, maturity, tendon continuity, and load-to failure of the repaired tendons at 12 weeks after repair. Importantly, the retracted tendon group demonstrated newly formed immature and disorganized fibrous tissue adjacent to the footprint, continuous with healthy tendinous cuff that retracted medially, away from the footprint. Although this new fibrous tissue was more disorganized, it did not have significantly decreased load-to-failure compared to the nonretracted tear and control groups. While providing helpful insights into what lies “beneath the surface” after retracted RCR, the current study failed to control for tension and strength of their transosseous repair technique. Similarly, it is unclear whether this fibrous tissue formed after acute partial tendon excision adequately reflects that tissue found in more chronic, retracted human rotator cuff tears, particularly with varying degrees of retraction.
      While current surgical techniques have evolved to address tendon retraction in an effort to minimize tension on RCR constructs, there is growing evidence that these repairs under relative tension may still experience “failure in continuity”. Soft tissue releases, interval slide techniques, marginal convergence, and footprint medialization all allow for reduced RCR tension but may not improve the tendon’s ultimate healing potential. Prior to Rhee et al.’s study, limited data existed on the biological and histological changes that result with these techniques. Toward this end, Rhee et al. provide new insight into the tissue changes seen in the repair of these medially retracted tears. Encouragingly, despite the more immature and disorganized fibrous tissue formed, there did not seem to be any biomechanical difference in load to failure in this small animal model. Future studies are required to evaluate these reported changes in human subjects in order to determine clinical significance and develop potential biological interventions to aid tendon healing.
      Ultimately, the Rhee et al. study finds that perhaps there is an additional area of intervention to improve healing. If techniques can be developed to facilitate a more favorable histological environment and optimize the strength of the postoperative fibrous tissue, there may be further improvement in healing rates and clinical outcomes. Future studies will be required to assess applicability of the authors’ findings to chronic rotator cuff tears in human subjects. However, this article provides an excellent starting point toward understanding the concept of failure in continuity and its implications for clinical function.

      Supplementary Data

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