Structural Musculotendinous Parameters That Predict Failed Tendon Healing After Rotator Cuff Repair

BACKGROUND: Healing of the rotator cuff after repair constitutes a major clinical challenge with reported high failure rates. Identifying structural musculotendinous predictors for failed rotator cuff repair could enable improved diagnosis and management of patients with rotator cuff disease. PURPOSE: To investigate structural predictors of the musculotendinous unit for failed tendon healing after rotator cuff repair. STUDY DESIGN: Cohort study; Level of evidence, 2. METHODS: Included were 116 shoulders of 115 consecutive patients with supraspinatus (SSP) tear documented on magnetic resonance imaging (MRI) who were treated with an arthroscopic rotator cuff repair. Preoperative assessment included standardized clinical and imaging (MRI) examinations. Intraoperatively, biopsies of the joint capsule, the SSP tendon, and muscle were harvested for histological assessment. At 3 and 12 months postoperatively, patients were re-examined clinically and with MRI. Structural and clinical predictors of healing were evaluated using logistic and linear regression models. RESULTS: Structural failure of tendon repair, which was significantly associated with poorer clinical outcome, was associated with older age (β = 1.12; 95% CI, 1.03 to 1.26; P = .03), shorter SSP tendon length (β = 0.89; 95% CI, 0.8 to 0.98; P = .02), and increased proportion of slow myosin heavy chain (MHC)-I/fast MHC-II hybrid muscle fibers (β = 1.23; 95% CI, 1.07 to 1.42; P = .004). Primary clinical outcome (12-month postoperative Constant score) was significantly less favorable for shoulders with fatty infiltration of the infraspinatus muscle (β = -4.71; 95% CI, -9.30 to -0.12; P = .044). Conversely, a high content of fast MHC-II muscle fibers (β = 0.24; 95% CI, 0.026 to 0.44; P = .028) was associated with better clinical outcome. CONCLUSION: Both decreased tendon length and increased hybrid muscle fiber type were independent predictors for retear. Clinical outcome was compromised by tendon retearing and increased fatty infiltration of the infraspinatus muscle. A high content of fast MHC-II SSP muscle fibers was associated with a better clinical outcome

Structural Musculotendinous Parameters That Predict Failed Tendon Healing After Rotator Cuff Repair

Background: Healing of the rotator cuff after repair constitutes a major clinical challenge with reported high failure rates. Identifying structural musculotendinous predictors for failed rotator cuff repair could enable improved diagnosis and management of patients with rotator cuff disease. Purpose: To investigate structural predictors of the musculotendinous unit for failed tendon healing after rotator cuff repair. Study Design: Cohort study; Level of evidence, 2. Methods: Included were 116 shoulders of 115 consecutive patients with supraspinatus (SSP) tear documented on magnetic resonance imaging (MRI) who were treated with an arthroscopic rotator cuff repair. Preoperative assessment included standardized clinical and imaging (MRI) examinations. Intraoperatively, biopsies of the joint capsule, the SSP tendon, and muscle were harvested for histological assessment. At 3 and 12 months postoperatively, patients were re-examined clinically and with MRI. Structural and clinical predictors of healing were evaluated using logistic and linear regression models. Results: Structural failure of tendon repair, which was significantly associated with poorer clinical outcome, was associated with older age (β = 1.12; 95% CI, 1.03 to 1.26; P =.03), shorter SSP tendon length (β = 0.89; 95% CI, 0.8 to 0.98; P =.02), and increased proportion of slow myosin heavy chain (MHC)–I/fast MHC-II hybrid muscle fibers (β = 1.23; 95% CI, 1.07 to 1.42; P =.004). Primary clinical outcome (12-month postoperative Constant score) was significantly less favorable for shoulders with fatty infiltration of the infraspinatus muscle (β = –4.71; 95% CI, –9.30 to –0.12; P =.044). Conversely, a high content of fast MHC-II muscle fibers (β = 0.24; 95% CI, 0.026 to 0.44; P =.028) was associated with better clinical outcome. Conclusion: Both decreased tendon length and increased hybrid muscle fiber type were independent predictors for retear. Clinical outcome was compromised by tendon retearing and increased fatty infiltration of the infraspinatus muscle. A high content of fast MHC-II SSP muscle fibers was associated with a better clinical outcome. Registration: NCT02123784 (ClinicalTrials.govidentifier).ISSN:2325-967

Changes of Supraspinatus Muscle Volume and Fat Fraction After Successful or Failed Arthroscopic Rotator Cuff Repair

BACKGROUND Muscle atrophy and fatty infiltration are limiting factors for successful rotator cuff (RC) repair. Quantitative data regarding these hallmarks of degenerative muscle changes after RC repair in humans are scarce. By utilizing a new application of the 6-point Dixon magnetic resonance imaging technology, 3-dimensional volume and fat fraction analysis of the whole RC muscle have become possible. PURPOSE Quantitative analysis of atrophy and fatty infiltration of the supraspinatus muscle after healed and failed RC tendon-to-bone repair. STUDY DESIGN Cohort study; Level of evidence, 3. METHODS Muscle volume and fat fraction were measured preoperatively and at 3 and 12 months postoperatively in 19 failed and 21 healed arthroscopic supraspinatus tendon repairs, with full muscle volume segmentation and magnetic resonance Dixon sequences. RESULTS In both groups, the muscle volume initially decreased 3 months after RC repair by -3% in intact (P = .140) and -10% in failed repair (P = .004) but recovered between 3 and 12 months to 103% (P = .274) in intact and 92% (P = .040) in failed repairs when compared with the preoperative volume (difference of change between groups, preoperative to 12 month: P = .013). The supraspinatus muscle's fat fraction did not significantly change after successful repair (6.5% preoperative, 6.6% after 3 months, and 6.7% after 12 months; all nonsignificant). There was, however, a significant increase from 7.8% to 10.8% at 3 months (P = .014) and 11.4% at 12 months (P = .020) after failed repair (difference between groups at 3- and 12-month follow-up: P = .018 and P = .001, respectively). CONCLUSION After successful arthroscopic repair, RC tendon tear-induced fatty infiltration can be almost stopped, and muscle atrophy can even be slightly reversed. In case of a failed repair, however, these changes are further pronounced during the first 3 postoperative months but seem to stabilize thereafter