We found no clinically significant differences between SR and DR repair groups, but MRA showed a significantly lower re-tear rate in the DR group compared to the SR group (25% vs. 60%. P
0.02). To the best of our knowledge, this is the first report on a 3 Tesla MRA in the evaluation of two different techniques for rotator cuff repair. A 3 Tesla scanner was used in order to reduce scanning time and improve image quality. The short scanning time (15
minutes) resulted in great patient satisfaction and low anxiety levels. Moreover, with intra-articular contrast medium, images have to be acquired within 40
minutes from the injection and a short scanning time helps to facilitate examination of the patient.
In previous reports, the use of 3 Tesla MR imaging has been shown to improve knee imaging because the signal-to-noise ratio for cartilage is significantly higher than at 1.5 Tesla [30
]. The signal-to-noise ratio obtained at 3 Tesla can also be used to obtain higher spatial resolution and/or to reduce the acquisition time. In addition, a recent study showed that, by using higher field strength, MR images of the ankle were obtained with excellent diagnostic quality and a reduction in imaging time of about 44% [28
]. Many studies have also been published about evaluation of the shoulder with a 3 Tesla magnet, with and without intra-articular contrast medium (MRA). The increase in signal offered by the high field enables improved visualization of bone, cartilage, tendons and ligaments. Thanks to the greater signal-to-noise ratio and improved spatial resolution, MR imaging at 3 Tesla is able to notably increase diagnostic performance in the musculoskeletal setting, compared to 1.5 Tesla, allowing for an unprecedented level of bone and soft tissue detail, with consequent improvement in patient treatment and management [28
]. For these reasons, evaluating the rotator cuff in operated patients with a 3 Tesla MRA permits a better imaging quality that improves detection of tears and ruptures. Moreover, assessment of the integrity of other structures is enhanced.
There are few studies in literature directly comparing the clinical results of SR and DR repair in the same setting, and none of them demonstrated any statistically significant difference between the two techniques [20
]. Our clinical results agree with those previously reported in literature; in fact, the SR and DR groups showed similar results on the CMS and SST, without any statistically significant difference.
To the best of our knowledge, only Franceschi et al. [25
] have reported on operative time and implant expense and concluded that DR repair has a statistically significant longer surgical time and a greater implant expense than SR repair. In agreement with Franceschi et al. [25
], DR repair in our study entailed longer surgical time and greater implant expense.
There are also few studies directly comparing the radiological results of SR and DR repair in the same setting [4
]. The re-tear rates observed in our two groups are similar to those reported in other published studies, ranging from 10% to 90% [3
]. There are only three level of evidence 1 studies in literature directly comparing the radiographic results of SR and DR rotator cuff repair [24
]. Franceschi et al. [25
] in their MRA study on large and massive rotator cuff tears, after 2
years of follow-up, reported 10 partial thickness defects and 2 full-thickness defects in 26 patients treated with SR repair, and 7 partial thickness defects and 1 full-thickness defect in 26 patients treated with DR repair. This difference was considered not statistically significant. They concluded that there are no advantages in using a DR technique to restore the anatomical footprint, and the mechanical advantages reported in many cadaveric studies do not translate into superior clinical performance when compared with the more traditional, less demanding, cheaper and more advantageous technique of SR repair. In their MRI study on small and medium-sized rotator cuff tears, Burks et al. [24
] reported the same re-tear rate (10%) in both SR and DR repair groups, but they followed up their patients for only one year. More recently, Koh et al. [44
] reported a full-thickness re-tear in 16.7% of the SR group patients and in 26.1% of the DR group patients, without any statistically significant difference. With partial re-tears also included, 62.5% of the patients in the SR group and 30.4% of the patients in the DR group had a re-tear; this difference was statistically significant. In their retrospective study, Cho et al. [43
] also reported similar re-tear rates following SR or DR rotator cuff repair at MRI 6
months after surgery, without statistically significant differences. The studies by Burks et al. [24
], Franceschi et al. [25
] and Koh et al. [44
] are level of evidence 1 studies, which are supposed to have the least possible bias, even though Franceschi et al. [25
] did not calculate the sample size, and Burks et al. [24
] argued that in their study there could be a type II error in finding a true difference between the SR and DR groups, which a larger number of patients might have revealed. The prospective study by Koh et al. [44
] was focused mainly on clinical results. MRI was performed only in less than 80% of the enrolled patients (77% in the SR group and 74% in the DR group), with a relevant “dropout” rate. The difference for full-thickness re-tear rates was not statistically significant, but with the given sample size the statistical power obtained was low. With partial re-tears also included, this difference was statistically significant; after Bonferroni correction, it was no longer statistically significant. As observed by the authors themselves, this correction test raises the possibility of a type II error and the results of the study should be interpreted with caution. It is important to consider that the results of rotator cuff repair are reported to decrease over time, and maybe the follow-up in these studies [24
] is not long enough to demonstrate a difference in the re-tear rate between the two techniques. To the best of our knowledge, the study by Sugaya et al. [45
], even though retrospective, with a 3-year follow-up is the longest follow-up study directly comparing SR and DR repairs in the same setting. They reported a 56% re-tear rate in the SR group and a 27% re-tear rate in the DR group at MRI, and the difference was considered statistically significant (p
0.01). In literature, conflicting results are reported about re-tear rates after SR and DR rotator cuff repair, with high level of evidence studies [8
] suggesting no differences between the two techniques, and retrospective studies reporting lower re-tear rates for DR repair [9
]. We think that more level of evidence 1 studies, with longer follow-up, are needed to demonstrate whether a difference exists in re-tear rates between SR and DR repair.
Some studies [47
] reported that the medial side of an intact supraspinatus tendon has equal, or maybe better, biomechanical properties than the lateral side, in terms of stiffness, pullout and work, and a tear in the tendon alters these properties only in the lateral side, but not in the medial side. The better biomechanical properties of the medial side of a torn supraspinatus tendon are related to larger collagen fibrils and greater fibril density, compared to the lateral tendon, that may provide a more robust matrix for resisting suture migration [48
]. In contrast, another study reported on similar fixation strength for SR and DR repair [14
]. We think that the lower re-tear rate observed in our patients in the DR group may be related to the protective effect of the medial row on the lateral row (strain shielding effect). As observed by Cho et al. [43
], this phenomenon may explain why, after SR repair, a re-tear occurs more frequently at the tendon-to-bone interface and, on the other hand, after DR repair, a re-tear occurs more frequently at the musculotendinous junction, because the lateral row is protected by the medial row. In our study, there were too few patients for a statistical correlation between re-tear localization and repair technique.
Several studies have documented better subjective and objective results of rotator cuff repair when the tendon has been documented to heal [1
], but we found no statistically significant differences in the clinical scores between our two groups, albeit the re-tear rate was significantly lower in our DR group (Figure
Figure 4 Coronal (A) and oblique sagittal (B) MRA views of the operated shoulder of a 48-year-old man (SR group), at 38-month follow-up, showed a type II tear of the rotator cuff, with a thin supraspinatus tendon (4.5mm thick), leakage of the contrast (more ...)
Better subjective and objective results have also been described in younger patients [49
]. We strongly agree with this observation, even though the small number of young patients in our two groups did not allow us to demonstrate any statistically significant correlation.
We observed some leakage of the contrast medium in all our cases, despite the clinical outcomes, even though in some cases it was very mild, and the tendon appeared healthy (homogeneous with normal thickness and no retraction). We hypothesized that leakage of the contrast medium took place at the interval between insertion of the tendons at the suture anchors level. In the study by Charousset et al. [20
], the patients were evaluated with CT arthrography, and the percentage of watertight healed rotator cuffs (no leakage of the contrast medium into the subacromial bursa, indicating perfect healing or a partial thickness defect) was 77.4% for the DR group, compared with 60.0% for the SR group (p
0.05). In the study of Franceschi et al. [25
], the patients were evaluated with MRA, and the percentage of intact cuffs and partial-thickness defects was 96% for the DR group, compared with 92% for the SR group (p
0.05). Charousset et al. [20
] clearly stated that leakage of the contrast medium was not related to anatomic healing with reestablishment of the native footprint. In their study it was achieved in 61.3% of the DR repairs, compared with 40% of the SR repairs, and this difference was significant (p
0.03). Franceschi et al. [25
] in their study did not discuss the difference between leakage of the contrast medium and healing of the footprint. As previously reported by Duc et al. [29
], sometimes something that seems a defect is actually an intact tendon, but distorted by a scar. In some cases, patients operated on for a rotator cuff tear, after a period of wellness, can experience pain in the operated shoulder for several reasons, not always related to the shoulder itself. Usually patients ask for, or another physician prescribes, imaging studies, that in some cases are performed with intra-articular contrast medium and/or with an ultrahigh magnetic field (3 Tesla MRA), as suggested by many papers. In such a case the radiologist might interpret the leakage of the contrast medium as a re-tear, without considering other parameters such as tendon thickness, retraction, signal intensity, insertion site, etc., and without any consideration of clinical function. We think that leakage of the contrast medium is due to an incomplete tendon-to-bone sealing, especially near suture anchors, or to an interstitial passage of the liquid among the fibrillated tendon fibers, especially if multiple strands of sutures are passed in the pulley technique through the cuff, creating large holes. We believe that imaging must be prescribed and interpreted on the basis of clinical findings, and leakage of the contrast medium does not in itself mean re-tear. This final consideration could have important medicolegal implications.
In a recent review of the literature about the clinical results of rotator cuff repair, Saridakis et al. [9
] suggested that surgeons should use a DR technique only for tears larger than 3
cm. On the other hand, Duquin et al. [51
], in a recent review of the literature about radiographic results of rotator cuff repair, including the studies by Burks et al. [24
] and Franceschi et al. [25
], suggested that surgeons should use a DR technique for all rotator cuff repairs, when possible, particularly for tears greater than 1
]. On the basis of our clinical findings and MRA results, and in accordance with these reviews [9
], we now reserve DR rotator cuff repairs for more active patients, with larger tear sizes, and SR repair for older, less active patients and for patients with smaller tear sizes.
Significant limitations are present in our study. First of all, this is a retrospective study with a relatively medium-term follow-up, and the radiologist was not blinded to the repair technique. But we have to consider that, in every study setting, even prospective ones, which compares the radiographic results of SR and DR repair, the radiologist cannot be really blinded about the surgical technique. In fact, he/she can count on MRA/MRI/CT scans the number of suture anchors placed in the footprint and determine whether they are in a SR or DR fashion. This introduces a potential, significant bias in the results reported by the radiologist even in prospective and “well-done” studies, which cannot be avoided. Furthermore, in our study the patients were not evaluated at a fixed follow-up time, but it ranged from 36 to 50
months in the SR group and from 36 to 43
months in the DR group. However, there was not a statistically significant difference in the mean length of follow-up between the two groups.
Our study also has some strengths. It is a single-surgeon series, with uniform surgical skills; we adopted rigid inclusion and exclusion criteria. The “dropout” rate in our study (20%) is acceptable and within the limits for “high-quality studies”. Injection of the contrast medium was done under ultrasound control to confirm intra-articular release, and all the patients were evaluated with a 3 Tesla MRA, which is able to notably increase diagnostic performance in the musculoskeletal setting, allowing for an unprecedented level of bone and soft tissue detail, with consequent improvement in patient treatment and management [28