Peripheral Microcirculation Alterations as an Indicator of Predisposition to Tendon Degeneration of the Shoulder Joint: A Preliminary Study

Introduction: The etiology of rotator cuff tear (RCT) is multifactorial and includes extrinsic and intrinsic factors. Alterations of the peripheral microcirculation represent a main intrinsic etiological factor; recent evidence demonstrates that at the level of the rotator cuff tendons there is significant reduction in capillary density and microvascular blood flow. On the basis of the alterations of the microcirculation present at the level of the rotator cuff (RC) tendons, the aim of our study was to evaluate the possible presence of alterations of the peripheral nail microcirculation, through capillaroscopic examination, in a consecutive series of patients with RCT, comparing them with an adequate control group. The hypothesis of our study is that the alteration of the local microcirculation is accompanied in patients with RCT by an alteration of the peripheral microcirculation that may represent a systemic predisposing factor for tendon degeneration. Materials and methods: A case-control study was conducted. The Case Group consisted of 82 patients (mean age 61 years ± 8) with RCT, the size of which was assessed intraoperatively and classified into small, large and massive according to Snyder; the control group was represented by 43 healthy subjects (mean age 63 years ± 9). All control subjects underwent ultrasound examination to objectively exclude rotator cuff tears. All participants underwent a nail capillaroscopic examination of the hands to evaluate morphological and dynamic parameters. The data was subsequently analyzed. Results: In the Case Group, 34 patients had a small RC lesion, 23 had a large lesion, and 25 had a massive lesion. The main capillaroscopic differences between cases and controls were found in the morphology of the capillary loops and in the flow. In the group of cases, 50% have normal loops, 47.56% have tortuous loops and 2.44% have branched loops; in the control group 62.79% had normal loops, 34.88% had tortuous loops and 2.33% had branched loops. The capillary flow was normal in 46.34% of the cases group, granular in 48.78% and slowed in 2.44%. 95.35% of the control group had normal flow and 2.33% grainy flow. Regarding the severity of the lesion, no significant differences were found between patients with small, large and massive lesion (small lesion: 50% normal loops, 41.2% normal flow; large lesion: 52% normal loops, 47.8% normal flow; massive lesion: 48% normal loops, 48% normal flow). Conclusions: The prevalence of capillaroscopic alterations was higher in patients with rotator cuff tears: the capillary loops are more tortuous and present ectasias more frequently than in the control group. Additionally, capillary flow in patients with RCT is grainier and slowed. However, the compromise of the capillary picture is not proportional to the severity of the tendon lesion, limiting the direct clinical applicability of this finding. The results support the hypothesis that peripheral microcirculation disorders constitute an etiological factor predisposing to tendon degeneration and, therefore, rupture. Further longitudinal studies are needed to assess whether these alterations can predict healing outcomes and risk of re-tear after surgical repair.