Simvastatin Exposure and Rotator Cuff Repair in a Rat Model

Current Research on the Influence of Statin Treatment on Rotator Cuff Healing

Rotator cuff tears are a condition characterized by damage to the muscles and tendons that connect the scapula and humerus, which are responsible for shoulder rotation and arm lifting. Metabolic factors such as diabetes, thyroid disease, high cholesterol, vitamin D deficiency, obesity, and smoking have been associated with an increased risk of rotator cuff tears. Interestingly, patients with hyperlipidemia, a condition characterized by high levels of cholesterol and other fats in the blood, have been found to have a higher incidence of rotator cuff tears and breakdown of tendon matrix. As a result, statin therapy, which is commonly used to lower cholesterol levels in hyperlipidemia, has been explored as a potential treatment to improve clinical outcomes in rotator cuff tears. However, the results of preclinical and clinical studies on the effects of statins on tendon healing in rotator cuff tears are limited and not well-defined. Moreover, since hyperlipidemia and rotator cuff tears are more prevalent in older individuals, a literature review on the efficacy and safety of statin therapy in this population is needed.

Does statin-treated hyperlipidemia affect rotator cuff healing or muscle fatty infiltration after rotator cuff repair?

BACKGROUND

Hyperlipidemia is linked to poor tendon-to-bone healing and progression of fatty infiltration after rotator cuff repair. Statins effectively treat hyperlipidemia, but it is unknown if they have any potential detrimental effects following rotator cuff repair. The aim of this study was to evaluate the effect of statins on rotator cuff healing and fatty infiltration following repair.

METHODS

A total of 77 patients undergoing arthroscopic rotator cuff repair were recruited prospectively, 38 patients who were prescribed a statin for hyperlipidemia (statin group) and 39 patients who were not taking a statin (control group). Patients who did not have both preoperative and 1-year postoperative magnetic resonance imaging (MRI) scans were excluded from the study. Patient-reported outcome measures, namely the Western Ontario Rotator Cuff (WORC) index, Constant-Murley score, American Shoulder and Elbow Surgeons (ASES) score, and Disabilities of the Arm, Shoulder and Hand (DASH) score, were collected preoperatively and at 1 year. Fatty infiltration was assessed on MRI according to the Goutallier grade preoperatively and at 12 months; rotator cuff healing was assessed at 12 months according to the Sugaya classification. Following propensity score weighting to adjust for baseline imbalances, 12-month outcomes were compared between the 2 groups.

RESULTS

At 12 months, all patient-reported outcome measures had improved significantly compared with baseline (WORC score, 85.9 vs. 32.5, P < .001; ASES score, 87.3 vs. 37.5, P < .001; Constant-Murley score, 77 vs. 31, P < .001; and DASH score, 13.6 vs. 61.4, P < .001). There was no significant difference in postoperative scores in the statin group vs. the control group (WORC score, 84.9 vs. 89.6, P = .94; ASES score, 87.5 vs. 86.6, P = .40; Constant-Murley score, 77 vs. 81, P = .90; and DASH score, 14.4 vs. 11.4, P = .14), and for 3 of these scores, the 95% confidence intervals excluded a clinically meaningful difference. Similarly, rotator cuff healing at 12 months and Goutallier fatty infiltration grades were comparable between the 2 groups. Retears were seen in 6 patients (15.8%) in the statin group and 8 (20.5%) in the control group. Progression of fatty infiltration was seen in 4 patients (10.5%) in the statin and 4 (10.3%) in the control group. Statin use did not demonstrate a significant association with either retear risk (P = .41) or progression of fatty atrophy (P = .69).

CONCLUSION

Patient-reported outcomes, rotator cuff retear rate, and fatty infiltration on MRI at 12 months after rotator cuff repair in patients with hyperlipidemia treated with statins are similar to those in a control group.

Overlay repair with a synthetic collagen scaffold improves the quality of healing in a rat rotator cuff repair model

BACKGROUND

Augmenting repairs with extracellular matrix-based scaffolds is a common option for rotator cuff tears. In this study, a new collagen scaffold was assessed for its efficacy in augmenting rotator cuff repair.

METHODS

The collagen scaffold was assessed in vitro for cytocompatibility and retention of tenocyte phenotype using alamarBlue assays, fluorescent imaging, and real-time polymerase chain reaction. Immunogenicity was assessed in vitro by the activation of human monocytes. In vivo, by use of a modified rat rotator cuff defect model, supraspinatus tendon repairs were carried out in 40 animals. Overlay augmentation with the collagen scaffold was compared with unaugmented repairs. At 6 and 12 weeks postoperatively, the repairs were tested biomechanically to evaluate repair strength, as well as histologically to assess quality of healing.

RESULTS

The collagen scaffold supported human tendon-derived cell growth in vitro, with cells demonstrating proliferation and appearing morphologically tenocytic over the experimental period. No immunogenic responses were provoked compared with suture material control. In vivo, augmentation with the scaffold improved the histologic scores at 12 weeks (8.4 of 15 vs 6.4 of 15, P = .032). However, no significant difference was detected with mechanical testing.

CONCLUSION

The new collagen scaffold was supportive of cell growth in vitro and generated a minimal acute inflammatory response. In vivo, we observed an improvement in the histologic appearance of the repair at 12 weeks. However, a meaningful increase in biomechanical strength was not achieved. Further modification and improvement of the scaffold are required prior to consideration for clinical use.

The effects of hyperlipidemia on rotator cuff diseases: a systematic review

BACKGROUND

Rotator cuff disease is a common condition that causes shoulder pain and functional disability. Recent studies suggested that hyperlipidemia might be associated with the development of rotator cuff disease. The objective of this study was to explore the relationship of hyperlipidemia and rotator cuff diseases.

METHODS

A computerized search using relevant search terms was performed in the PubMed, EMBASE, and Cochrane Library databases, as well as a manual search of reference and citation lists of the included studies. Searches were limited to studies that explored the association of hyperlipidemia and rotator cuff diseases.

RESULTS

Sixteen studies were included in this systematic review. Ten of sixteen included studies suggested an association between dyslipidemia and rotator cuff diseases, while the other six studies did not find an association. Two studies demonstrated there were an association between statins and reduced risk of developing rotator cuff diseases or decreased incidence of revision after rotator cuff repair.

CONCLUSION

The current study suggested that there was an association between hyperlipidemia and rotator cuff diseases. Furthermore, current evidence suggested that use of statins could decrease the risk of developing rotator cuff diseases and the incidence of revision after rotator cuff repair. Future high-quality studies are highly needed to confirm these findings.

Hyperlipidemia increases the risk of retear after arthroscopic rotator cuff repair

BACKGROUND

Hyperlipidemia (HL) has been identified as a risk factor for rotator cuff tear, but no studies have evaluated its effects on healing. The purpose of this study was to evaluate the effect of HL and statin use on rotator cuff healing after arthroscopic repair.

METHODS

This was a retrospective review of 85 patients (86 shoulders) who underwent arthroscopic rotator cuff repair with postoperative ultrasound evaluation. Ultrasound findings were graded no retear, partial-thickness retear (PT), or full-thickness retear (FT).

RESULTS

Average age was 62.1 years (45.3-74.3 years). On ultrasound evaluation, 65 shoulders (75.5%) had no retear, 14 (16.3%) had PT, and 7 (8.1%) had FT. There was no significant difference in retear rate by age, technique, or tissue quality. There were 33 patients (38.8%) who had the diagnosis of HL, and all were taking a statin medication. Compared with patients without HL, patients with HL had significantly higher rates of FT (18.1% vs. 1.9%; P < .001) and PT (27.2% vs. 9.4%; P < .001). The total retear rate (PT and FT) for HL patients was significantly higher at 45.5% (15/33) compared with the patients without HL at 11.3% (6/53), with an odds ratio of 6.5 (P < .001). There was no difference in retear rate by dosage or type of statin mediation.

CONCLUSION

After arthroscopic rotator cuff repair, HL was a risk factor for retear. Further investigation is warranted on this topic, and these results may help in managing expectations after surgery.