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Rotator cuff repair with all-suture anchors: a midterm magnetic resonance imaging evaluation of repair integrity and cyst formation
ARTICLE IN PRESS J Shoulder Elbow Surg (2018) ■■, ■■–■■
www.elsevier.com/locate/ymse
ORIGINAL ARTICLE
Rotator cuff repair with all-suture anchors: a midterm magnetic resonance imaging evaluation of repair integrity and cyst formation Hans Van der Bracht, MD, PhDa,1,*, Tom Van den Langenbergh, MDb,1, Marc Pouillon, MDc, Skrallan Verhasselt, MDd, Philippe Verniers, MDa, Danny Stoffelen, MD, PhDe a
Department of Orthopaedic Surgery and Traumatology, Algemeen Ziekenhuis St-Lucas, Gent, Belgium Department of Orthopaedic Surgery and Traumatology, University Hospital Antwerp, Antwerp, Belgium c Department of Radiology, GasthuisZusters Antwerpen Hospitals, Wilrijk, Belgium d Department of Orthopaedic Surgery and Traumatology, University Hospital Leuven, Leuven, Belgium e Department of Orthopaedic Surgery and Traumatology, GasthuisZusters Antwerpen Hospitals, Wilrijk, Belgium b
Background: This study investigated the feasibility and safety of all-suture anchors in arthroscopic rotator cuff repair. Methods: All patients were diagnosed with a rotator cuff tear by ultrasound or magnetic resonance imaging (MRI). Patients with partial tears, massive tears, subscapularis tears, or previous shoulder surgery, were excluded. MRI and clinical outcome were investigated in all patients at 1.58 years (range, 1.0-2.0 years) after rotator cuff repair with all-suture anchors (prospective case series). Integrity of the cuff repair, cyst formation (encapsulated fluid signal around the anchor), ingrowth of the bone into the anchor, and integrity of the bone tunnel border were evaluated for 47 anchors. Clinical results were evaluated using the Constant-Murley score. Results: An MRI evaluation was performed in 20 patients at 1.58 years (range, 1.0-2.0 years) after rotator cuff repair with all-suture anchors. MRI evaluation showed a very small rim of fluid around 10% of the anchors. None of the anchors showed cyst formation with fluid diameter more than twice the anchor diameter. In approximately 90% of the anchors, no fluid could be detected between the anchors and the edge of the bony tunnel. Full rotator cuff integrity was seen in 19 patients. Only 1 patient sustained a retear. Clinical results comparable with an arthroscopic rotator cuff repair using classic anchors were seen. Conclusions: This prospective clinical cohort study shows promising early radiographic and clinical results after arthroscopic rotator cuff repair using all-suture anchors. Level of evidence: Level IV; Case Series; Treatment Study © 2018 Journal of Shoulder and Elbow Surgery Board of Trustees. All rights reserved. Keywords: Shoulder; rotator cuff repair; rotator cuff integrity; all-suture anchors; cyst formation; MRI
The Commissie Medische Ethiek GZA Ziekenhuizen approved this study (No. 141006ACADEM). *Reprint requests: Hans Van der Bracht, MD, PhD, Department of Orthopaedic Surgery, AZ St- Lucas, Groenebriel 1, B-9000 Gent, Belgium. E-mail address: [email protected] (H. Van der Bracht). 1 These authors contributed equally to this work. 1058-2746/$ - see front matter © 2018 Journal of Shoulder and Elbow Surgery Board of Trustees. All rights reserved. https://doi.org/10.1016/j.jse.2018.03.006
ARTICLE IN PRESS 2 Rotator cuff tears are one of the most common shoulder disorders, often leading to pain and loss of shoulder function. As these lesions may cause impairment, surgical repair is often the final treatment.1,27 During the last decade, arthroscopic rotator cuff repair with suture anchors has become the gold standard.1,10,27 Single and double-row repair, both using suture anchors, are widely used. A wide variety of suture anchors is available for the fixation of tendons to bone.27 These suture anchors vary in size, shape, composition, methods of insertion and fixation, radiopacity, and mechanical properties.3,27 New anchors with improved mechanical properties continue to be released in an attempt to reduce failure rates.27 The first-generation of suture anchors were metallic devices (stainless steel or titanium), which provided excellent fixation but were associated with failures such as loosening and intraarticular migration.9,12,15,18,20,22,29 Metallic artefact also distorts postoperative assessment by magnetic resonance imaging (MRI). A second-generation of nonmetallic anchors (poly-ether-etherketone and bioabsorbable anchors) was therefore developed to overcome some of the disadvantages of metallic anchors.9,20,24 These nonmetallic anchors should be easier to deal with in case of revision surgery, and some of them are biodegradable and may offer anchor resorption and bone integration.4,27 Bioabsorbable anchors are associated with complications such as eyelet breakage, osteolysis, and intraosseous cyst formation.20,27 A third-generation of all-suture anchors was recently introduced. All-suture anchors have some theoretical advantages in arthroscopic rotator cuff repair compared with first- and second-generation anchors. First, these anchors are completely composed of soft components, decreasing the loose body complications and joint damage associated with classic anchors. Second, smaller drill holes need to be made into the bone, leading to improved bone preservation. Third, no distortion will be seen on the MRI assessment. Several studies have investigated biomechanical properties of all-suture anchors, suggesting similar pull-out strength and load to failure compared with traditional anchors.3,11,13,21 Since that time, all-suture anchors are being widely used in arthroscopic shoulder surgery; however, no clinical and radiographic in vivo studies have been published. Furthermore, an in vivo animal study showed that all-suture anchors are at risk for clinical failure caused by micromotion and cyst-like cavities.26 As far as we know, this is the first in vivo clinical study evaluating MRI results and clinical outcome of all-suture anchors in arthroscopic rotator cuff repair. This study was performed to investigate the feasibility and safety of all-suture anchors in arthroscopic rotator cuff repair.
H. Van der Bracht et al. diagnosed with a rotator cuff tear by ultrasound imaging or MRI. After patients with partial tears, massive tears (2 or more tendons involved), subscapularis tears, or previous shoulder surgery were excluded for further investigation, 28 patients met the inclusion criteria. Of these 28 patients, 8 patients could not undergo further MRI and clinical evaluation (1 lost to follow-up, 5 contraindications for MRI, and 2 patients had a new trauma of the shoulder that required revision shoulder surgery). There were 20 patients (12 men, 8 women) available for MRI and clinical evaluation at least 1 year after rotator cuff repair. The mean age at the time of operation was 57.4 years (range, 44.5-66.5 years). Mean duration of follow-up was 1.6 years (range, 1.0 -2.0 years). The dominant shoulder was affected in 75%. Informed consent was obtained for all patients included in this study.
Surgical procedure All patients were treated with a standardized arthroscopic doublerow rotator cuff repair by a single surgeon (H.V.d.B.).17 Surgery was performed in the beach chair position. A classical posterior portal was used for intra-articular inspection. Tenotomy of the long head of the biceps tendon was performed in 85% of the patients. The arthroscope was brought in the subacromial space, and a bursectomy was performed with a radiofrequency probe. The tear was evaluated with the arthroscope in the lateral portal. Footprint preparation was performed with an oval burr to create a bleeding cancellous bone bed. Two accessory lateral portals and a Neviaser portal were made for pilot hole drilling (2.9 mm), anchor placement, cuff positioning, and knot tying. An acromioplasty was performed in 70% of the patients. For the purpose of this study, only “all-suture anchors” (2.9mm JuggerKnot Anchors; Biomet, Warsaw, IN, USA) were used for medial and lateral rows (Fig. 1). These anchors are completely suturebased implants. The anchor is deployable and consists of 2 highstrength MaxBraid Sutures (Biomet) that pass through a 2-mmwide and 25-mm-long flexible sleeve of braided polyester material. This sleeve bunches up under a cortical surface to provide an anchoring effect and secures the 2 sutures in place. The number of anchors used depended on the size of the tear. A standardized postoperative protocol was used. Four weeks of passive immobilization with a sling was required. Passive exercises were allowed from the first postoperative day. Free active and
Materials and methods Patient selection This prospective clinical cohort study enrolled 50 consecutive patients requiring arthroscopic rotator cuff repair. All patients were
Figure 1 Double-row rotator cuff repair with the use of the allsuture anchor.
ARTICLE IN PRESS Rotator cuff repair with all-suture anchors passive motion was allowed after 4 to 6 weeks, depending on tear size. Cuff strengthening exercises were started 6 weeks postoperatively. Return to sport or manual labor was allowed a minimal of 3 months after the surgery and after a reassuring clinical evaluation.
Postoperative MRI evaluation All patients underwent a postoperative MRI at least 1 year after surgery (average, 1.53 years; range, 1.0-2.0 years). All shoulder MRI examinations were performed with a 3-Tesla MR scanner (Verio Siemens, Erlangen, Germany), with a dedicated shoulder coil. The imaging protocol included the following sequences (total imaging time: 19 minutes 15 seconds): 1. T1 turbo spin echo (TSE) coronal: 20 slices; repetition time (TR), 550 ms; echo time (TE), 11 ms; voxel size, 0.6 × 0.6 × 2.5 mm; acquisition time (TA), 1:46; 2. T2 BLADE TSE coronal: 20 slices; TR, 2450 ms; TE, 52 ms; fat saturation (FATSAT), voxel size: 0.5 × 0.5 × 2.5 mm; TA, 4:11; 3. T2 BLADE TSE sagittal: 30 slices; TR, 6620 ms; TE, 103 ms; FATSAT, voxel size: 0.5 × 0.5 × 2.5 mm; TA, 3:53; 4. T2 BLADE TSE axial: 24 slices; TR, 5300 ms; TE, 103 ms; FATSAT, voxel size: 0.5 × 0.5 × 2.5 mm; TA, 4:48; and 5. T2 true fast imaging with steady state precession (TrueFISP): 144 slices; TR, 8.67 ms; TE, 3.74 ms; isotropic voxels (0.5 × 0.5 × 0.5) with reconstructions in sagittal, axial, and coronal plane; TA, 4:37. The images were reviewed by an experienced senior radiologist (M.P.) specialized in musculoskeletal radiology. First, the integrity of the cuff repair (n = 20) was evaluated. An intact cuff was defined as maintenance of the insertion into the footprint, and an unhealed cuff was defined as a discontinuity at the footprint. The integrity of the cuff repair was graded as follows: grade 1, normal thickness and intact; grade 2, increasing signal on T2 but no fluid on TrueFISP and intact; grade 3, loss of thickness without tear; grade 4, retear (high signal intensity area [fluid-equivalent signal] or discontinuity of the supraspinatus or infraspinatus tendon in 1 or more of the standard T2-weighted images and the TrueFISP sequence).16,19,20,25 Second, the fluid signal around the anchor on multiple T2 weighted images (coronal and sagittal) and TrueFISP sequence was graded as follows for each individual anchor (n = 47): grade 0, no fluid signal around the anchor; grade 1, minimal fluid collections; grade 2, local collection of fluid; grade 3, fluid collection around the entire length of the anchor, with diameter less than twice the anchor diameter (<6 mm); and grade 4, encapsulated fluid (cyst) around the anchor with diameter larger than twice the anchor diameter.20 If no fluid signal around the anchor was observed (TrueFISP negative), an increased signal on intermediary T2 images was scored similarly as the fluid signal.20 Third, to determine ingrowth of the bone into the anchor, the intensity of the signal from the region around the anchor site (grade 1 to 3) was graded as follows for each individual anchor (n = 47): grade 1, a hyperintense signal in T2 sequences and hypointense signal in TSE T1-weighted sequence, interpretable as an early stage; grade 2, incomplete isointensity of the signals of the T2 and T1 sequences, which can be considered as an intermediate stage of bone apposition; and grade 3, isointense signals from bone ingrowth in
3 the T2 and T1 sequences, considered to indicate late-stage or complete bone apposition.27 Fourth, integrity of the tunnel border (grade 0 to 2) was graded as follows for each individual anchor (n = 47): grade 0, the wall of the tunnel is easily identifiable and characterized by a thin, uninterrupted low-intensity signal on the TrueFISP sequence; grade 1, partial discontinuity of the walls of the tunnel; grade 2, lack of a detectable border.27
Clinical evaluation All patients were clinically evaluated. A visual analog scale (VAS) for pain was obtained preoperatively. Postoperative evaluation was done at least 1 year after surgery (average, 1.53 years; range, 1.02.0 years) A VAS score for pain, an absolute Constant-Murley score, and a VAS score for satisfaction were obtained postoperatively.6,7,10,19 Strength of the operated-on supraspinatus muscle was compared with the contralateral side by use of a dynamometer.
Statistical analysis Statistical analysis was performed with SPSS 23 software (IBM, Armonk, NY, USA). Level of significance was accepted at P < .05. Data are presented with means and standard deviations (SD). A 2-sided t test was used to compare preoperative and postoperative data (Constant-Murley score, VAS, and supraspinatus muscle strength).
Results We evaluated 20 arthroscopic double-row rotator cuff repairs in 20 patients. A total of 48 all-suture anchors were initially used and were independently evaluated. An average of 2 anchors was used in each repair; in 8 patients with a larger cuff tear, 3 anchors were needed to obtain a full coverage of the footprint. A deep wound infection occurred in 1 patient. A repeat arthroscopy was performed 61 days after the index procedure. An arthroscopic débridement with removal of 1 loose lateral anchor was performed. The 2 medial anchors remained in place; thus, 47 suture anchors were available for further MRI evaluation.
Postoperative MRI evaluation First, the integrity of the cuff repair was evaluated in 20 patients. Results are reported in Table I. A retear was observed at the level of the footprint in 1 patient, but no retraction was
Table I
Grade of the integrity of the rotator cuff repair
Variable
Grade 1
Integrity of the rotator cuff
2
3
4
No.
No.
No.
No.
3
9
7
1
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H. Van der Bracht et al. Table II
Grade of fluid collection around the anchor site
Variable
Fluid signal around the anchor (hyperintense signal on T2 and TrueFISP) Increased signal on intermediary T2 images (if negative signal on TrueFISP)
Grade 0
1
2
3
4
No.
No.
No.
No.
No.
43
0
0
5
0
0
0
0
43
0
TrueFISP, true fast imaging with steady state precession.
seen. Small tears were observed in 5 patients at the level of the musculotendinous junction (Table I). Second, the fluid signal around the anchor on T2-weighted images and TrueFISP sequence was graded for each individual anchor (n = 47). A local collection of fluid that was not encapsulated (hyperintense signal on T2 and TrueFISP sequences) was detected in 10.4% of anchors (Table II; Fig. 2).
No fluid signal around the anchor (no hyperintense signal on TrueFISP sequence) was seen in 89.6% of anchors. For the 43 anchors with no fluid signal around the anchor, the increased signal on intermediary T2 images was scored.5 All of those anchors had an increased signal on intermediary T2 images around the entire length of the anchor, with a diameter less than twice the anchor diameter (<6 mm; Fig. 3, Table II). Third, to determine ingrowth of bone into the anchor, the intensity of the signal from the region around the anchor site was graded for each individual anchor (n = 47). In all patients, there was a zone of high signal on T2 (89.6% TrueFISP negative), interposed between the anchor and the tunnel edge. Therefore, in none of the anchors bone apposition could be observed (Figs. 2, B and 3, B). Fourth, integrity of the tunnel edge was graded for the 47 anchors individually, and grade 0 integrity of the tunnel edge could be observed for all anchors. The wall of the tunnel could therefore easily be identified and characterized by a thin, uninterrupted, low-intensity signal on the TrueFISP sequence (Figs. 2, A and 3, A).
Figure 2 A local collection of nonencapsulated fluid around the anchor (arrow). Hyperintense signal on (A) true fast imaging with steady state precession sequence (also note the thin uninterrupted tunnel border) and (B) on T2 sequence.
Figure 3 Patient with no fluid around the anchor. (A) No high signal around the anchor on true fast imaging with steady state precession sequence (also note the thin uninterrupted tunnel border) but (B) increased signal on intermediary T2 images. Note that the increased signal does not have the same intensity as the fluid in the joint. The arrows show the 2 anchors.
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Clinical evaluation The average VAS score for pain improved significantly from 6.88 (SD, 2.02) preoperatively to 2.12 (SD, 1.74) postoperatively (P = .0001). The average postoperative VAS score for satisfaction was 9.18 (range, 7-10). The average postoperative Constant-Murley score was 79.05 (range, 55-90). No statistically significant difference between force of the supraspinatus between the operated (5.61 [SD, 1.90] kg) and the nonoperated-on shoulder (6.42 [SD, 1.31] kg) could be detected (P = .074).
Discussion The MRI evaluation of 20 patients who had an arthroscopic rotator cuff repair with all-suture anchors showed a very small rim of fluid around 10% of the anchors. None of the anchors showed cyst formation with fluid diameter more than twice the anchor diameter. In approximately 90% of the anchors, no fluid could be detected between the anchors and the edge of the bony tunnel. Full rotator cuff integrity was seen in 19 patients, with only 1 patient sustaining a retear. During the last decade, arthroscopic rotator cuff repair with suture anchors became the gold standard for treatment of symptomatic rotator cuff tears.1,9,10,27 A third-generation anchor—the all-suture anchor—was recently developed. On one hand, in vitro animal studies show comparable fixation strength of all-suture anchors compared with traditional screw anchors,3,11 and no biomechanical difference was seen between traditional anchors and all-suture anchors in a double-row rotator cuff repair in a cadaveric model.13 On the other hand, an in vivo animal study by Pfeiffer et al26 examined histologic and biomechanical characteristics of 2 smaller allsuture anchors and showed that the anchor sites were cystlike cavities with a rim of dense lamellar bone. These results suggested all-suture anchors may be at risk for clinical failure.26 Furthermore, a biomechanical study by Mazzocca et al21 evaluating classic and all-suture anchors for glenoid labral repair showed that all-suture anchors are susceptible to micromotion and early gap formation. Therefore, whether all-suture anchors can be used safely in arthroscopic rotator cuff repair is not clear. This study was performed to investigate the clinical feasibility of using allsuture anchors in arthroscopic rotator cuff repair. MRI evaluation was performed 1.53 years (range, 1.02.0 years) after double-row arthroscopic rotator cuff repair of full-thickness supraspinatus tendon tears. For the purpose of this study, only all-suture anchors were used. Routine T1 and T2 sequences were obtained, and a TrueFISP sequence was performed to detect local fluid collections. The MRI evaluation showed a recurrent pattern around the all-suture anchors: (1) the anchor central in a bony tunnel, (2) a rim of higher signal on T2 sequence, (3) an easily identified tunnel border, and (4) the spongious bone of the humeral head (Fig. 4).
Figure 4 True fast imaging with steady state precession sequence shows recurrent pattern of ingrowth and tunnel formation around all suture anchors. The pattern consists of (1) the anchor central in the tunnel (white arrow), (2) a rim of higher signal on the T2 sequence (red arrow), (3) an easily identified tunnel border (green arrow), note that the signal has the same intensity of the cortical bone of the greater tuberosity (yellow arrow), and (4) the spongious bone of the humeral head (blue arrow). (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)
We presume that a limited tunnel widening (less than twice the anchor diameter), comparable to tunnel widening seen after anterior cruciate ligament surgery, is seen around each anchor.28 The tunnel widening is mainly V-shaped, with the broadest part at the surface of the bone. The rim of high signal on T2 sequences between the anchor and the tunnel border most probably corresponds to fibrous scar tissue around most of the anchors. Fibrous-elastic scar tissue is also found between the graft and the tunnel border in anterior cruciate ligament reconstructions.28 The TrueFISP sequence, used to detect stationary fluid, shows that approximately 10.4% of the anchors the high signal zone on T2 sequences consists of fluid. No fluid was found around 89.6% of the anchors. A real cyst formation with encapsulated fluid was not seen around any of the anchors. Similar MRI findings were seen in the only other in vivo study in which allsuture anchors were used in the shoulder.30 This study by Willemot et al30 investigated early radiographic and clinical outcomes after arthroscopic Bankart repair using all-suture anchors and showed no large cyst formation (58 anchors used). Small cysts were found in 2 patients (2 anchors), and tunnel widening was apparent in 3 patients. These results are comparable to our findings and confirm the safe use of all-suture anchors in shoulder surgery. The cyst-like formation around anchors, as described by Pfeiffer et al26 in their animal study, was not seen in both of the human in vivo studies performed so far. A classic finding on MRI is that repaired rotator cuff tendons have a variable appearance in the first postoperative year. With
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time, a low-intensity signal produced by fibrotic tissue develops on all sequences. Studies show that only 10% of repaired tendons demonstrate the normal, native low-signal intensity.2,5,8 Our study shows that despite the limited tunnel widening and the high signal rim between the anchor and the tunnel edge on T2 sequences, the anchors remain well in place, and an adequate tendon-to-bone healing is seen. The integrity of the rotator cuff repair and clinical outcome with all-suture anchors are similar to other studies where classic anchors are used. The present study has several weaknesses. First, the sample size is relatively small, and the study design lacks a comparative control group. However, we used strict inclusion criteria, and no study in the literature has evaluated the MRI result and clinical outcome of all-suture anchors in arthroscopic rotator cuff repair. Because of the limited sample size, a post hoc power analysis was not listed. Second, our minimum follow-up of 1 year is rather short. Mihata et al23 investigated the integrity of the rotator cuff after an arthroscopic repair in 201 patients up to 24 months after different techniques of repair by repetitious MRI. Only 1 additional retear was seen at the 2-year follow-up compared with the 1-year follow-up. This suggests that a 1-year follow-up period is a reliable time frame to evaluate the structural integrity of the rotator cuff repair.14,23
Conclusion Although this study was performed on a limited number of patients with a minimum follow-up of 1 year, we believe that the MRI findings confirm the hypothesis that allsuture anchors can be safely used in arthroscopic rotator cuff repair. We do not confirm the previous findings of the animal study by Pfeiffer et al26 in which cyst-like cavities were seen, suggesting all-suture anchors may be at risk for clinical failure. This study shows that all-suture anchors allow an adequate tendon-to-bone healing and give similar clinical results compared with classic anchors. Furthermore, the use of all-suture anchors in arthroscopic rotator cuff repair (1) reduces the risk of loose body complications and joint damage, (2) leads to improved bone preservation, and (3) avoids distortion of MRI assessment. Larger-scale clinical trials will be necessary to confirm the clinical findings and detect potential complications.
Disclaimer Hans Van der Bracht is a consultant for Zimmer Biomet, and travel/accommodation expenses were covered or reimbursed by Zimmer Biomet. Marc Pouillon received a research grant from Zimmer Biomet for this study. The other authors, their immediate families, and any research foundations with which they are affiliated have not received any financial payments or other benefits from any commercial entity related to the subject of this article.
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ORIGINAL ARTICLE
Rotator cuff repair with all-suture anchors: a midterm magnetic resonance imaging evaluation of repair integrity and cyst formation Hans Van der Bracht, MD, PhDa,1,*, Tom Van den Langenbergh, MDb,1, Marc Pouillon, MDc, Skrallan Verhasselt, MDd, Philippe Verniers, MDa, Danny Stoffelen, MD, PhDe a
Department of Orthopaedic Surgery and Traumatology, Algemeen Ziekenhuis St-Lucas, Gent, Belgium Department of Orthopaedic Surgery and Traumatology, University Hospital Antwerp, Antwerp, Belgium c Department of Radiology, GasthuisZusters Antwerpen Hospitals, Wilrijk, Belgium d Department of Orthopaedic Surgery and Traumatology, University Hospital Leuven, Leuven, Belgium e Department of Orthopaedic Surgery and Traumatology, GasthuisZusters Antwerpen Hospitals, Wilrijk, Belgium b
Background: This study investigated the feasibility and safety of all-suture anchors in arthroscopic rotator cuff repair. Methods: All patients were diagnosed with a rotator cuff tear by ultrasound or magnetic resonance imaging (MRI). Patients with partial tears, massive tears, subscapularis tears, or previous shoulder surgery, were excluded. MRI and clinical outcome were investigated in all patients at 1.58 years (range, 1.0-2.0 years) after rotator cuff repair with all-suture anchors (prospective case series). Integrity of the cuff repair, cyst formation (encapsulated fluid signal around the anchor), ingrowth of the bone into the anchor, and integrity of the bone tunnel border were evaluated for 47 anchors. Clinical results were evaluated using the Constant-Murley score. Results: An MRI evaluation was performed in 20 patients at 1.58 years (range, 1.0-2.0 years) after rotator cuff repair with all-suture anchors. MRI evaluation showed a very small rim of fluid around 10% of the anchors. None of the anchors showed cyst formation with fluid diameter more than twice the anchor diameter. In approximately 90% of the anchors, no fluid could be detected between the anchors and the edge of the bony tunnel. Full rotator cuff integrity was seen in 19 patients. Only 1 patient sustained a retear. Clinical results comparable with an arthroscopic rotator cuff repair using classic anchors were seen. Conclusions: This prospective clinical cohort study shows promising early radiographic and clinical results after arthroscopic rotator cuff repair using all-suture anchors. Level of evidence: Level IV; Case Series; Treatment Study © 2018 Journal of Shoulder and Elbow Surgery Board of Trustees. All rights reserved. Keywords: Shoulder; rotator cuff repair; rotator cuff integrity; all-suture anchors; cyst formation; MRI
The Commissie Medische Ethiek GZA Ziekenhuizen approved this study (No. 141006ACADEM). *Reprint requests: Hans Van der Bracht, MD, PhD, Department of Orthopaedic Surgery, AZ St- Lucas, Groenebriel 1, B-9000 Gent, Belgium. E-mail address: [email protected] (H. Van der Bracht). 1 These authors contributed equally to this work. 1058-2746/$ - see front matter © 2018 Journal of Shoulder and Elbow Surgery Board of Trustees. All rights reserved. https://doi.org/10.1016/j.jse.2018.03.006
ARTICLE IN PRESS 2 Rotator cuff tears are one of the most common shoulder disorders, often leading to pain and loss of shoulder function. As these lesions may cause impairment, surgical repair is often the final treatment.1,27 During the last decade, arthroscopic rotator cuff repair with suture anchors has become the gold standard.1,10,27 Single and double-row repair, both using suture anchors, are widely used. A wide variety of suture anchors is available for the fixation of tendons to bone.27 These suture anchors vary in size, shape, composition, methods of insertion and fixation, radiopacity, and mechanical properties.3,27 New anchors with improved mechanical properties continue to be released in an attempt to reduce failure rates.27 The first-generation of suture anchors were metallic devices (stainless steel or titanium), which provided excellent fixation but were associated with failures such as loosening and intraarticular migration.9,12,15,18,20,22,29 Metallic artefact also distorts postoperative assessment by magnetic resonance imaging (MRI). A second-generation of nonmetallic anchors (poly-ether-etherketone and bioabsorbable anchors) was therefore developed to overcome some of the disadvantages of metallic anchors.9,20,24 These nonmetallic anchors should be easier to deal with in case of revision surgery, and some of them are biodegradable and may offer anchor resorption and bone integration.4,27 Bioabsorbable anchors are associated with complications such as eyelet breakage, osteolysis, and intraosseous cyst formation.20,27 A third-generation of all-suture anchors was recently introduced. All-suture anchors have some theoretical advantages in arthroscopic rotator cuff repair compared with first- and second-generation anchors. First, these anchors are completely composed of soft components, decreasing the loose body complications and joint damage associated with classic anchors. Second, smaller drill holes need to be made into the bone, leading to improved bone preservation. Third, no distortion will be seen on the MRI assessment. Several studies have investigated biomechanical properties of all-suture anchors, suggesting similar pull-out strength and load to failure compared with traditional anchors.3,11,13,21 Since that time, all-suture anchors are being widely used in arthroscopic shoulder surgery; however, no clinical and radiographic in vivo studies have been published. Furthermore, an in vivo animal study showed that all-suture anchors are at risk for clinical failure caused by micromotion and cyst-like cavities.26 As far as we know, this is the first in vivo clinical study evaluating MRI results and clinical outcome of all-suture anchors in arthroscopic rotator cuff repair. This study was performed to investigate the feasibility and safety of all-suture anchors in arthroscopic rotator cuff repair.
H. Van der Bracht et al. diagnosed with a rotator cuff tear by ultrasound imaging or MRI. After patients with partial tears, massive tears (2 or more tendons involved), subscapularis tears, or previous shoulder surgery were excluded for further investigation, 28 patients met the inclusion criteria. Of these 28 patients, 8 patients could not undergo further MRI and clinical evaluation (1 lost to follow-up, 5 contraindications for MRI, and 2 patients had a new trauma of the shoulder that required revision shoulder surgery). There were 20 patients (12 men, 8 women) available for MRI and clinical evaluation at least 1 year after rotator cuff repair. The mean age at the time of operation was 57.4 years (range, 44.5-66.5 years). Mean duration of follow-up was 1.6 years (range, 1.0 -2.0 years). The dominant shoulder was affected in 75%. Informed consent was obtained for all patients included in this study.
Surgical procedure All patients were treated with a standardized arthroscopic doublerow rotator cuff repair by a single surgeon (H.V.d.B.).17 Surgery was performed in the beach chair position. A classical posterior portal was used for intra-articular inspection. Tenotomy of the long head of the biceps tendon was performed in 85% of the patients. The arthroscope was brought in the subacromial space, and a bursectomy was performed with a radiofrequency probe. The tear was evaluated with the arthroscope in the lateral portal. Footprint preparation was performed with an oval burr to create a bleeding cancellous bone bed. Two accessory lateral portals and a Neviaser portal were made for pilot hole drilling (2.9 mm), anchor placement, cuff positioning, and knot tying. An acromioplasty was performed in 70% of the patients. For the purpose of this study, only “all-suture anchors” (2.9mm JuggerKnot Anchors; Biomet, Warsaw, IN, USA) were used for medial and lateral rows (Fig. 1). These anchors are completely suturebased implants. The anchor is deployable and consists of 2 highstrength MaxBraid Sutures (Biomet) that pass through a 2-mmwide and 25-mm-long flexible sleeve of braided polyester material. This sleeve bunches up under a cortical surface to provide an anchoring effect and secures the 2 sutures in place. The number of anchors used depended on the size of the tear. A standardized postoperative protocol was used. Four weeks of passive immobilization with a sling was required. Passive exercises were allowed from the first postoperative day. Free active and
Materials and methods Patient selection This prospective clinical cohort study enrolled 50 consecutive patients requiring arthroscopic rotator cuff repair. All patients were
Figure 1 Double-row rotator cuff repair with the use of the allsuture anchor.
ARTICLE IN PRESS Rotator cuff repair with all-suture anchors passive motion was allowed after 4 to 6 weeks, depending on tear size. Cuff strengthening exercises were started 6 weeks postoperatively. Return to sport or manual labor was allowed a minimal of 3 months after the surgery and after a reassuring clinical evaluation.
Postoperative MRI evaluation All patients underwent a postoperative MRI at least 1 year after surgery (average, 1.53 years; range, 1.0-2.0 years). All shoulder MRI examinations were performed with a 3-Tesla MR scanner (Verio Siemens, Erlangen, Germany), with a dedicated shoulder coil. The imaging protocol included the following sequences (total imaging time: 19 minutes 15 seconds): 1. T1 turbo spin echo (TSE) coronal: 20 slices; repetition time (TR), 550 ms; echo time (TE), 11 ms; voxel size, 0.6 × 0.6 × 2.5 mm; acquisition time (TA), 1:46; 2. T2 BLADE TSE coronal: 20 slices; TR, 2450 ms; TE, 52 ms; fat saturation (FATSAT), voxel size: 0.5 × 0.5 × 2.5 mm; TA, 4:11; 3. T2 BLADE TSE sagittal: 30 slices; TR, 6620 ms; TE, 103 ms; FATSAT, voxel size: 0.5 × 0.5 × 2.5 mm; TA, 3:53; 4. T2 BLADE TSE axial: 24 slices; TR, 5300 ms; TE, 103 ms; FATSAT, voxel size: 0.5 × 0.5 × 2.5 mm; TA, 4:48; and 5. T2 true fast imaging with steady state precession (TrueFISP): 144 slices; TR, 8.67 ms; TE, 3.74 ms; isotropic voxels (0.5 × 0.5 × 0.5) with reconstructions in sagittal, axial, and coronal plane; TA, 4:37. The images were reviewed by an experienced senior radiologist (M.P.) specialized in musculoskeletal radiology. First, the integrity of the cuff repair (n = 20) was evaluated. An intact cuff was defined as maintenance of the insertion into the footprint, and an unhealed cuff was defined as a discontinuity at the footprint. The integrity of the cuff repair was graded as follows: grade 1, normal thickness and intact; grade 2, increasing signal on T2 but no fluid on TrueFISP and intact; grade 3, loss of thickness without tear; grade 4, retear (high signal intensity area [fluid-equivalent signal] or discontinuity of the supraspinatus or infraspinatus tendon in 1 or more of the standard T2-weighted images and the TrueFISP sequence).16,19,20,25 Second, the fluid signal around the anchor on multiple T2 weighted images (coronal and sagittal) and TrueFISP sequence was graded as follows for each individual anchor (n = 47): grade 0, no fluid signal around the anchor; grade 1, minimal fluid collections; grade 2, local collection of fluid; grade 3, fluid collection around the entire length of the anchor, with diameter less than twice the anchor diameter (<6 mm); and grade 4, encapsulated fluid (cyst) around the anchor with diameter larger than twice the anchor diameter.20 If no fluid signal around the anchor was observed (TrueFISP negative), an increased signal on intermediary T2 images was scored similarly as the fluid signal.20 Third, to determine ingrowth of the bone into the anchor, the intensity of the signal from the region around the anchor site (grade 1 to 3) was graded as follows for each individual anchor (n = 47): grade 1, a hyperintense signal in T2 sequences and hypointense signal in TSE T1-weighted sequence, interpretable as an early stage; grade 2, incomplete isointensity of the signals of the T2 and T1 sequences, which can be considered as an intermediate stage of bone apposition; and grade 3, isointense signals from bone ingrowth in
3 the T2 and T1 sequences, considered to indicate late-stage or complete bone apposition.27 Fourth, integrity of the tunnel border (grade 0 to 2) was graded as follows for each individual anchor (n = 47): grade 0, the wall of the tunnel is easily identifiable and characterized by a thin, uninterrupted low-intensity signal on the TrueFISP sequence; grade 1, partial discontinuity of the walls of the tunnel; grade 2, lack of a detectable border.27
Clinical evaluation All patients were clinically evaluated. A visual analog scale (VAS) for pain was obtained preoperatively. Postoperative evaluation was done at least 1 year after surgery (average, 1.53 years; range, 1.02.0 years) A VAS score for pain, an absolute Constant-Murley score, and a VAS score for satisfaction were obtained postoperatively.6,7,10,19 Strength of the operated-on supraspinatus muscle was compared with the contralateral side by use of a dynamometer.
Statistical analysis Statistical analysis was performed with SPSS 23 software (IBM, Armonk, NY, USA). Level of significance was accepted at P < .05. Data are presented with means and standard deviations (SD). A 2-sided t test was used to compare preoperative and postoperative data (Constant-Murley score, VAS, and supraspinatus muscle strength).
Results We evaluated 20 arthroscopic double-row rotator cuff repairs in 20 patients. A total of 48 all-suture anchors were initially used and were independently evaluated. An average of 2 anchors was used in each repair; in 8 patients with a larger cuff tear, 3 anchors were needed to obtain a full coverage of the footprint. A deep wound infection occurred in 1 patient. A repeat arthroscopy was performed 61 days after the index procedure. An arthroscopic débridement with removal of 1 loose lateral anchor was performed. The 2 medial anchors remained in place; thus, 47 suture anchors were available for further MRI evaluation.
Postoperative MRI evaluation First, the integrity of the cuff repair was evaluated in 20 patients. Results are reported in Table I. A retear was observed at the level of the footprint in 1 patient, but no retraction was
Table I
Grade of the integrity of the rotator cuff repair
Variable
Grade 1
Integrity of the rotator cuff
2
3
4
No.
No.
No.
No.
3
9
7
1
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H. Van der Bracht et al. Table II
Grade of fluid collection around the anchor site
Variable
Fluid signal around the anchor (hyperintense signal on T2 and TrueFISP) Increased signal on intermediary T2 images (if negative signal on TrueFISP)
Grade 0
1
2
3
4
No.
No.
No.
No.
No.
43
0
0
5
0
0
0
0
43
0
TrueFISP, true fast imaging with steady state precession.
seen. Small tears were observed in 5 patients at the level of the musculotendinous junction (Table I). Second, the fluid signal around the anchor on T2-weighted images and TrueFISP sequence was graded for each individual anchor (n = 47). A local collection of fluid that was not encapsulated (hyperintense signal on T2 and TrueFISP sequences) was detected in 10.4% of anchors (Table II; Fig. 2).
No fluid signal around the anchor (no hyperintense signal on TrueFISP sequence) was seen in 89.6% of anchors. For the 43 anchors with no fluid signal around the anchor, the increased signal on intermediary T2 images was scored.5 All of those anchors had an increased signal on intermediary T2 images around the entire length of the anchor, with a diameter less than twice the anchor diameter (<6 mm; Fig. 3, Table II). Third, to determine ingrowth of bone into the anchor, the intensity of the signal from the region around the anchor site was graded for each individual anchor (n = 47). In all patients, there was a zone of high signal on T2 (89.6% TrueFISP negative), interposed between the anchor and the tunnel edge. Therefore, in none of the anchors bone apposition could be observed (Figs. 2, B and 3, B). Fourth, integrity of the tunnel edge was graded for the 47 anchors individually, and grade 0 integrity of the tunnel edge could be observed for all anchors. The wall of the tunnel could therefore easily be identified and characterized by a thin, uninterrupted, low-intensity signal on the TrueFISP sequence (Figs. 2, A and 3, A).
Figure 2 A local collection of nonencapsulated fluid around the anchor (arrow). Hyperintense signal on (A) true fast imaging with steady state precession sequence (also note the thin uninterrupted tunnel border) and (B) on T2 sequence.
Figure 3 Patient with no fluid around the anchor. (A) No high signal around the anchor on true fast imaging with steady state precession sequence (also note the thin uninterrupted tunnel border) but (B) increased signal on intermediary T2 images. Note that the increased signal does not have the same intensity as the fluid in the joint. The arrows show the 2 anchors.
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Clinical evaluation The average VAS score for pain improved significantly from 6.88 (SD, 2.02) preoperatively to 2.12 (SD, 1.74) postoperatively (P = .0001). The average postoperative VAS score for satisfaction was 9.18 (range, 7-10). The average postoperative Constant-Murley score was 79.05 (range, 55-90). No statistically significant difference between force of the supraspinatus between the operated (5.61 [SD, 1.90] kg) and the nonoperated-on shoulder (6.42 [SD, 1.31] kg) could be detected (P = .074).
Discussion The MRI evaluation of 20 patients who had an arthroscopic rotator cuff repair with all-suture anchors showed a very small rim of fluid around 10% of the anchors. None of the anchors showed cyst formation with fluid diameter more than twice the anchor diameter. In approximately 90% of the anchors, no fluid could be detected between the anchors and the edge of the bony tunnel. Full rotator cuff integrity was seen in 19 patients, with only 1 patient sustaining a retear. During the last decade, arthroscopic rotator cuff repair with suture anchors became the gold standard for treatment of symptomatic rotator cuff tears.1,9,10,27 A third-generation anchor—the all-suture anchor—was recently developed. On one hand, in vitro animal studies show comparable fixation strength of all-suture anchors compared with traditional screw anchors,3,11 and no biomechanical difference was seen between traditional anchors and all-suture anchors in a double-row rotator cuff repair in a cadaveric model.13 On the other hand, an in vivo animal study by Pfeiffer et al26 examined histologic and biomechanical characteristics of 2 smaller allsuture anchors and showed that the anchor sites were cystlike cavities with a rim of dense lamellar bone. These results suggested all-suture anchors may be at risk for clinical failure.26 Furthermore, a biomechanical study by Mazzocca et al21 evaluating classic and all-suture anchors for glenoid labral repair showed that all-suture anchors are susceptible to micromotion and early gap formation. Therefore, whether all-suture anchors can be used safely in arthroscopic rotator cuff repair is not clear. This study was performed to investigate the clinical feasibility of using allsuture anchors in arthroscopic rotator cuff repair. MRI evaluation was performed 1.53 years (range, 1.02.0 years) after double-row arthroscopic rotator cuff repair of full-thickness supraspinatus tendon tears. For the purpose of this study, only all-suture anchors were used. Routine T1 and T2 sequences were obtained, and a TrueFISP sequence was performed to detect local fluid collections. The MRI evaluation showed a recurrent pattern around the all-suture anchors: (1) the anchor central in a bony tunnel, (2) a rim of higher signal on T2 sequence, (3) an easily identified tunnel border, and (4) the spongious bone of the humeral head (Fig. 4).
Figure 4 True fast imaging with steady state precession sequence shows recurrent pattern of ingrowth and tunnel formation around all suture anchors. The pattern consists of (1) the anchor central in the tunnel (white arrow), (2) a rim of higher signal on the T2 sequence (red arrow), (3) an easily identified tunnel border (green arrow), note that the signal has the same intensity of the cortical bone of the greater tuberosity (yellow arrow), and (4) the spongious bone of the humeral head (blue arrow). (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)
We presume that a limited tunnel widening (less than twice the anchor diameter), comparable to tunnel widening seen after anterior cruciate ligament surgery, is seen around each anchor.28 The tunnel widening is mainly V-shaped, with the broadest part at the surface of the bone. The rim of high signal on T2 sequences between the anchor and the tunnel border most probably corresponds to fibrous scar tissue around most of the anchors. Fibrous-elastic scar tissue is also found between the graft and the tunnel border in anterior cruciate ligament reconstructions.28 The TrueFISP sequence, used to detect stationary fluid, shows that approximately 10.4% of the anchors the high signal zone on T2 sequences consists of fluid. No fluid was found around 89.6% of the anchors. A real cyst formation with encapsulated fluid was not seen around any of the anchors. Similar MRI findings were seen in the only other in vivo study in which allsuture anchors were used in the shoulder.30 This study by Willemot et al30 investigated early radiographic and clinical outcomes after arthroscopic Bankart repair using all-suture anchors and showed no large cyst formation (58 anchors used). Small cysts were found in 2 patients (2 anchors), and tunnel widening was apparent in 3 patients. These results are comparable to our findings and confirm the safe use of all-suture anchors in shoulder surgery. The cyst-like formation around anchors, as described by Pfeiffer et al26 in their animal study, was not seen in both of the human in vivo studies performed so far. A classic finding on MRI is that repaired rotator cuff tendons have a variable appearance in the first postoperative year. With
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time, a low-intensity signal produced by fibrotic tissue develops on all sequences. Studies show that only 10% of repaired tendons demonstrate the normal, native low-signal intensity.2,5,8 Our study shows that despite the limited tunnel widening and the high signal rim between the anchor and the tunnel edge on T2 sequences, the anchors remain well in place, and an adequate tendon-to-bone healing is seen. The integrity of the rotator cuff repair and clinical outcome with all-suture anchors are similar to other studies where classic anchors are used. The present study has several weaknesses. First, the sample size is relatively small, and the study design lacks a comparative control group. However, we used strict inclusion criteria, and no study in the literature has evaluated the MRI result and clinical outcome of all-suture anchors in arthroscopic rotator cuff repair. Because of the limited sample size, a post hoc power analysis was not listed. Second, our minimum follow-up of 1 year is rather short. Mihata et al23 investigated the integrity of the rotator cuff after an arthroscopic repair in 201 patients up to 24 months after different techniques of repair by repetitious MRI. Only 1 additional retear was seen at the 2-year follow-up compared with the 1-year follow-up. This suggests that a 1-year follow-up period is a reliable time frame to evaluate the structural integrity of the rotator cuff repair.14,23
Conclusion Although this study was performed on a limited number of patients with a minimum follow-up of 1 year, we believe that the MRI findings confirm the hypothesis that allsuture anchors can be safely used in arthroscopic rotator cuff repair. We do not confirm the previous findings of the animal study by Pfeiffer et al26 in which cyst-like cavities were seen, suggesting all-suture anchors may be at risk for clinical failure. This study shows that all-suture anchors allow an adequate tendon-to-bone healing and give similar clinical results compared with classic anchors. Furthermore, the use of all-suture anchors in arthroscopic rotator cuff repair (1) reduces the risk of loose body complications and joint damage, (2) leads to improved bone preservation, and (3) avoids distortion of MRI assessment. Larger-scale clinical trials will be necessary to confirm the clinical findings and detect potential complications.
Disclaimer Hans Van der Bracht is a consultant for Zimmer Biomet, and travel/accommodation expenses were covered or reimbursed by Zimmer Biomet. Marc Pouillon received a research grant from Zimmer Biomet for this study. The other authors, their immediate families, and any research foundations with which they are affiliated have not received any financial payments or other benefits from any commercial entity related to the subject of this article.
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