Biomechanical characteristics of the horizontal mattress stitch: implication for double-row and suture-bridge rotator cuff repair

doi:10.1007/s00776-013-0504-0

Journal of Orthopaedic Science

Volume 19, Issue 2, March 2014, Pages 235-241

https://doi.org/10.1007/s00776-013-0504-0 Get rights and content

Abstract

Background

We investigated the effects of bite-size horizontal mattress stitch (distance between the limbs passed through the tendon) on the biomechanical properties of the repaired tendon.

Methods

We anchored 20 bovine Achilles tendons to bone using no. 2 high-strength suture and 5-mm titanium suture anchors in a mattress-suture technique. Tendons were allocated randomly into two groups of ten each to receive stitches with a 4- or 10-mm bite. Specimens underwent cyclic loading from 5 to 30 N at 1 mm/s for 30 cycles, followed by tensile testing to failure. Gap formation, tendon strain, hysteresis, stiffness, yield load, ultimate load, energy to yield load, and energy to ultimate load were compared between groups using unpaired t tests.

Results

The 4-mm group had less (p < 0.05) gap formation and less (p < 0.05) longitudinal strain than did the 10-mm group. Ultimate load (293.6 vs. 148.9 N) and energy to ultimate load (2,563 vs. 1,472 N-mm) were greater (p < 0.001) for the 10-mm group than the 4-mm group. All tendons repaired with 4-mm suturing failed at the suture-tendon interface, with sutures pulling through the tendon, whereas the suture itself failed before the tendon did in seven of the ten specimens in the 10-mm group.

Conclusions

Whereas a 4-mm bite fixed the tendon more tightly but at the cost of decreased ultimate strength, a 10-mm bite conveyed greater ultimate strength but with increased gap and strain. These results suggest that for the conventional double-row repair, small mattress stitches provide a tighter repair, whereas large stitches are beneficial to prevent sutures from pulling through the tendon after surgery. For suture-bridge rotator cuff repair, large stitches are beneficial because the repaired tendon has a higher strength, and the slightly mobile medial knot can be tightened by lateral fixation.

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Cited by (18)

Biomechanical characteristics of a new looping stitch versus the classic Krackow stitch for distal biceps fixation
2023, JSES International
The purpose of this study was to quantify the biomechanical characteristics of a new looping stitch, developed with the concepts of a looping, locking stitch that decreases needle penetrations of the tendon, and compare it to a classic Krackow stitch for distal biceps suture-tendon fixation.
The Krackow stitch with No. 2 braided suture and the looping stitch with a No. 2 braided suture loop attached to a 25-mm-length by 1.3-mm-width polyblend suture tape were compared. The Looping stitch was performed with single strand locking loops and wrapping suture around the tendon, resulting in half the needle penetrations through the graft compared to the Krackow stitch. Ten matched pairs of human distal biceps tendons were used. One side of each pair was randomly assigned to either the Krackow or the looping stitch, and the contralateral side was used for the other stitch. For biomechanical testing, each construct was preloaded to 5 N for 60 seconds, followed by cyclic loading to 20 N, 40 N, and 60 N for 10 cycles each, and then loaded to failure. The deformation of the suture-tendon construct, stiffness, yield load, and ultimate load were quantified. Comparisons between the Krackow and looping stitches were performed with a paired t-test using P < .05 as statistically significant.
The Krackow stitch and looping stitch had no significant difference in stiffness, peak deformation, or nonrecoverable deformation after 10 cycles of loading to 20 N, 40 N, and 60 N. There was no difference between the Krackow stitch and looping stitch in load applied to displacement of 1 mm, 2 mm, and 3 mm. The ultimate load showed that the looping stitch was significantly stronger compared to the Krackow stitch (Krackow stitch: 223.7 ± 50.3 N; looping stitch: 312.7 ± 53.8 N) (P = .002). The failure modes were either suture breakage or tendon cut through. For the Krakow stitch, there was 1 suture breakage and 9 tendons cut through. For the looping stitch, there were five suture breakages, and five tendons cut through.
With fewer needle penetrations, incorporation of 100% of the tendon diameter, and a higher ultimate load to failure compared to the Krackow stitch, the Looping stitch may be a viable option to reduce deformation, failure, and cut-out of the suture-tendon construct.
The effect of loop size on loop security and elongation of a knot
2020, Orthopaedics and Traumatology: Surgery and Research
Citation Excerpt :
Each group with different loop circumferences was tested with 10 separate samples (n = 10). Primarily, a 7 N preload was applied and the elongation was recorded which reflected the “loop security” [2,9,10]. Our secondary criteria was elongation under cyclic loading between 7 and 30 N at a strain rate of 12 mm/min for 1000 cycles [10].
While repairing a teared rotator cuff tendon with suture anchors and horizontal mattress suture configurations, knots should be secure at time zero while approximating the tendon to the bone, otherwise any failure in loop security may cause undesired clinical results. Optimum distance between suture limbs passed through the tendon, in other words the bite size, is still not clear in the literature. The aim of this study was to test the effect of loop size, which is directly related to the bite size, on loop security and elongation of a knot.
We hypothesized that a knot with a smaller loop size would be more secure. We asked if a knot with shorter circumference (1) would offer a better knot security; (2) would produce less elongation following repeated traction cycles.
Two parallel metal rods in 3.0 mm diameter were fixed to load cells of dynamic testing machine. Four groups, from A to D, had the initial rod to rod distances of 2-4-6-8 mm respectively (n = 10). Surgeon's knots were prepared with 2/0 Ultrabraid® sutures around the rods. A tension meter was used for tying each half hitch under equal tension. Crosshead distances were recorded after 7 N pre-load and subsequent 1000 repetitive cyclic loads between 7-30 N.
Elongations after a 7 N preload for groups A to D were 0.107 mm (± 0.006), 0.143 mm (± 0.018), 0,16 mm (± 0.025), 0.185 mm (± 0.018) respectively. This increase was significant (p < 0.05, power > 0.95) between each group except between groups B and C. Maximum elongations after 1000^th cycle for groups A to D were 0.32 mm (± 0.124), 1.12 mm (± 0.333), 1.162 mm (± 0.211), 1.292 mm (± 0.241) respectively. Only samples in group A (0.732 mm ± 0.124) elongated significantly less than others (p < 0.05, power > 0.95). No knots unravelled or ruptured.
This study basically reports that a knot with a shorter loop circumference has superior properties regarding loop security and resistance to elongation. From the perspective of clinical importance, shorter distance between suture limbs of mattress configuration may provide a more secure fixation of the rotator cuff tendon to the bone.
II.
Biomechanics of an interlinked suture anchor rotator cuff repair in a human cadaveric model
2019, JSES Open Access
The purpose of this study was to evaluate the initial fixation of a transosseous-equivalent rotator cuff repair and an interlinked medial repair, quantifying the cyclic and failure loading properties of each construct.
Twenty-four human cadaveric shoulders from 12 matched pairs were dissected, and full-thickness supraspinatus tears were created. In each pair, 1 side was repaired with a transosseous-equivalent repair (control) and the other, with an interlinked repair. All specimens were cycled to 1 MPa of effective stress at 1 Hz for 500 cycles, and gap formation was recorded with a digital video system. All samples were then loaded to failure, and the ultimate load and displacement and modes of failure were recorded.
The interlinked repair showed a decrease in the amount of construct gapping after cycle 50 and in peak construct gapping compared with the control group (control, 3.4 ± 0.9 mm; interlinked, 2.5 ± 0.8 mm; P = .048). The interlinked repair also showed a higher ultimate load to failure (control, 318.7 ± 77.9 N; interlinked, 420.6 ± 93.7 N; P = .007). No other significant differences were detected between constructs for preparation or testing metrics.
The interlinked repair, in which 1 continuous suture linked the medial anchors, showed decreased construct gapping and increased ultimate load to failure compared with the control construct. This study establishes the biomechanical validity of the new interlinked repair construct compared with a previously validated construct.
Subacromial bone erosion due to suture-knots in arthroscopic rotator cuff repair: A report of two cases
2019, Asia-Pacific Journal of Sports Medicine, Arthroscopy, Rehabilitation and Technology
Citation Excerpt :
In addition, a long-term follow-up study showed that 93% (13 of 14) of patients with postoperative recurrent tears experienced proximal humeral migration or cuff tear arthropathy.4 To prevent recurrent rotator cuff tears, repair techniques have been developed to increase the security of fixation of the torn tendon to the bone, such as an increase in the number of knots and anchors used,5 an increase in the bite size,6 or the use of double-row fixation1,3,7,8 or suture-bridge fixation.1,8–14 A biomechanical study has shown that increasing the number of knots, stitches, and suture anchors significantly increases the primary stability of the various rotator cuff repair interfaces.5
Knot impingement can cause shoulder-joint motion pain after rotator-cuff repair. Previous studies have revealed only subacromial effusion in magnetic resonance imaging (MRI) evaluations of knot impingement. We report two cases of patients with symptomatic knot impingement. In both patients, bursal-side partial-thickness tear of the supraspinatus tendon had been repaired by a single-row technique using one suture anchor and two polyester sutures with a long-chain polyethylene core. Three-dimensional computed tomography and arthroscopy revealed bony erosion at the lateral side of the anterior half of the acromial undersurface in both patients. The size of the erosion was 1.7 cm (anteroposterior direction) × 0.7 cm (mediolateral direction) in one patient and 1.2 cm × 0.5 cm in the other. Arthroscopy showed that suture knots that had been placed at the muscle–tendon junction of the supraspinatus tendon were impinging on the area of bone erosion during shoulder abduction. Although the sutures themselves were of soft material, knot-tying made them stiff and thus led to bone erosion. Surgeons need to be aware of the possibility of subacromial bone erosion caused by suture knots in arthroscopic rotator cuff repair.
Pullout Strength of All-Suture Anchors: Effect of the Insertion and Traction Angle—A Biomechanical Study
2018, Arthroscopy - Journal of Arthroscopic and Related Surgery
To evaluate the pullout strength of the all-suture anchor (ASA), based on the angles of anchor insertion and traction.
Synthetic saw bones of 2 densities (0.16 and 0.32 g/cm³) with 3 mm thick cortical bone models were used. ASAs were inserted at 45°, 60°, 75°, or 90° and pulled at 2 angles from the surface: 45° (simulating the physiological pull of the supraspinatus) and 90° (simulating pulling out during knot tying). Five consecutive pullout tests for each insertion and traction angle combination per saw bone were conducted to evaluate the ultimate load to failure and mode of failure (80 tests total). Thereafter, 9 matched pairs of human cadaveric humeri with 2 ASA types were used (insertion angles, 45°, 75°, 90°; traction angle, 90°). Nine consecutive tests were conducted for each insertion angle and anchor type (54 tests total).
The pullout strength was significantly higher for high density- than for low-density saw bones (all P < .05). The pullout strength was higher at the 45°than at the 90° traction angle (all P < .05) and was significantly higher at the 90° and 75° than at the 45° insertion angle in both high-density saw bones and cadaveric humeri (all P < .05). However, the pullout strength was not significantly different by ASA type (all P > .05).
ASA showed stronger pullout strength in higher density bones. Furthermore, it presented stronger pullout strength in the physiological traction direction of supraspinatus rather than in the knot-tying direction, consistent with the deadman theory. However, stronger pullout strength was observed in the vertically directed insertion angle, not 45°. Therefore, implanting the ASA vertically may be clinically more beneficial not only when performing knot tying during surgery, but also when the supraspinatus tendon loads the ASA postoperatively.
The study provides biomechanical evidence that the optimal insertion angle for an ASA is more vertical than the 45°.
Editorial Commentary: Musculotendinous Junction Mattress Sutures Are Inefficient
2017, Arthroscopy - Journal of Arthroscopic and Related Surgery

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Original ArticleBiomechanical characteristics of the horizontal mattress stitch: implication for double-row and suture-bridge rotator cuff repair

Abstract

Background

Methods

Results

Conclusions

J Shoulder Elbow Surg.

J Shoulder Elbow Surg.

Arthroscopy.

Arthroscopy.

Arthroscopy.

Arthroscopic repair of full-thickness tears of the supraspinatus: does the tendon really heal?

J Bone Joint Surg Am.

The outcome and repair integrity of completely arthroscopically repaired large and massive rotator cuff tears

J Bone Joint Surg Am.

Functional and anatomical results after rotator cuff repair

Clin Orthop Relat Res.

Repairs of the rotator cuff. Correlation of functional results with integrity of the cuff

J Bone Joint Surg Am

Clinical outcome after structural failure of rotator cuff repairs

J Bone Joint Surg Am.

Arthroscopic rotator cuff repair with double-row fixation

J Bone Joint Surg Am.

Functional and structural outcomes of single-row versus double-row versus combined double-row and suture-bridge repair for rotator cuff tears

Am J Sports Med.

Original Article
Biomechanical characteristics of the horizontal mattress stitch: implication for double-row and suture-bridge rotator cuff repair