Biomechanical Evaluation of Transosseous Rotator Cuff Repair: Do Anchors Really Matter?

University Hospitals Case Medical Center, Cleveland, Ohio.
The American Journal of Sports Medicine (Impact Factor: 4.36). 12/2012; 41(2). DOI: 10.1177/0363546512469092
Source: PubMed


BACKGROUND:Suture anchor fixation has become the preferred method for arthroscopic repairs of rotator cuff tears. Recently, newer arthroscopic repair techniques including transosseous-equivalent repairs with anchors or arthroscopic transosseous suture passage have been developed. PURPOSE:To compare the initial biomechanical performance including ultimate load to failure and localized cyclic elongation between transosseous-equivalent repair with anchors (TOE), traditional transosseous repair with a curved bone tunnel (TO), and an arthroscopic transosseous repair technique utilizing a simple (AT) or X-box suture configuration (ATX). STUDY DESIGN:Controlled laboratory study. METHODS:Twenty-eight human cadaveric shoulders were dissected to create an isolated supraspinatus tear and randomized into 1 of 4 repair groups (TOE, TO, AT, ATX). Tensile testing was conducted to simulate the anatomic position of the supraspinatus with the arm in 60° of abduction and involved an initial preload, cyclic loading, and pull to failure. Localized elongation during testing was measured using optical tracking. Data were statistically assessed using analysis of variance with a Tukey post hoc test for multiple comparisons. RESULTS:The TOE repair demonstrated a significantly higher mean ± SD failure load (558.4 ± 122.9 N) compared with the TO (325.3 ± 79.9 N), AT (291.7 ± 57.9 N), and ATX (388.5 ± 92.6 N) repairs (P < .05). There was also a significantly larger amount of first-cycle excursion in the AT group (8.19 ± 1.85 mm) compared with the TOE group (5.10 ± 0.89 mm). There was no significant difference between repair groups in stiffness during maximum load to failure or in normalized cyclic elongation. Failure modes were as follows: TOE, tendon (n = 4) and bone (n = 3); TO, suture (n = 6) and bone (n = 1); AT, tendon (n = 2) and bone (n = 3) and suture (n = 1); ATX, tendon (n = 7). CONCLUSION:This study demonstrates that anchorless repair techniques using transosseous sutures result in significantly lower failure loads than a repair model utilizing anchors in a TOE construct. CLINICAL RELEVANCE:Suture anchor repair appears to offer superior biomechanical properties to transosseous repairs regardless of tunnel or suture configuration.

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    ABSTRACT: The aim of this study was to test a simple technique to augment the pullout resistance of an anchor in an over-drilled sheep humerus model. Sixty-four paired sheep humeri were harvested from 32 male sheep aged 18 months. Specimens were divided into an augmented group and non-augmented group. FASTIN RC 5-mm titanium screw anchors (DePuy Mitek, Raynham, MA) double loaded with suture material (braided polyester, nonabsorbable USP No. 2) were used in both groups. Osteoporosis was simulated by over-drilling with a 4.5-mm drill. Augmentation was performed by fixing 1 of the sutures 1.5 cm inferior to the anchor insertion site with a washer screw. This was followed by a pull-to-failure test at 50 mm/min. The ultimate load (the highest value of strength before anchor pullout) was recorded. A paired t test was used to compare the biomechanical properties of the augmented and non-augmented groups. In all specimens the failure mode was pullout of the anchor. The ultimate failure loads were statistically significantly higher in the augmented group (P < .0001). The mean pullout strength was 121.1 ± 10.17 N in the non-augmented group and 176.1 ± 10.34 N in the augmented group. The described augmentation technique, which is achieved by inferior-lateral fixation of 1 of the sutures of the double-loaded anchor to a fully threaded 6.5-mm cancellous screw with a washer, significantly increases the ultimate failure loads in the over-drilled sheep humerus model. Our technique is simple, safe, and inexpensive. It can be easily used in all osteoporotic patients and will contribute to the reduction of anchor failure. This technique might be difficult to apply arthroscopically. Cannulated smaller screws would probably be more practical for arthroscopic use. Further clinical studies are needed.
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    ABSTRACT: This human cadaveric study compares the biomechanical properties of quadriceps tendon repair with suture anchors and the commonly applied transosseous sutures. The hypothesis was that suture anchors provide at least equal results concerning gap formation and ultimate failure load compared with transosseous suture repair. Thirty human cadaveric knees underwent tenotomy followed by repair with either 5.5-mm-double-loaded suture anchors [titanium (TA) vs. resorbable hydroxyapatite (HA)] or transpatellar suture tunnels using No. 2 Ultrabraid™ and the Krackow whipstitch. Biomechanical analysis included pretensioning the constructs with 20 N for 30 s and then cyclic loading of 250 cycles between 20 and 100 N at 1 Hz in a servohydraulic testing machine with measurement of elongation. Ultimate failure load analysis and failure mode analysis were performed subsequently. Tendon repairs with suture anchors yielded significantly less gap formation during cyclic loading (20th-250th cycle: TA 1.9 ± 0.1, HA 1.5 ± 0.5, TS 33.3 ± 1.9 mm, p < 0.05) and resisted significantly higher ultimate failure loads (TA 740 ± 204 N, HA 572 ± 67 N, TS 338 ± 60 N, p < 0.05) compared with transosseous sutures. Common failure mode was pull-out of the eyelet within the suture anchor in the HA group and rupture of the suture in the TA and TS group. Quadriceps tendon repair with suture anchors yields significantly better biomechanical results than the commonly applied transosseous sutures in this human cadaveric study. These biomechanical findings may change the future clinical treatment for quadriceps tendon ruptures. Randomised controlled clinical trials are desirable for the future. Not applicable, controlled laboratory human cadaveric study.
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    ABSTRACT: Background The transosseous approach has been well known for a long time as a valid repair approach. Over time various criticisms have been raised over this technique principally classifiable in two main categories: technical difficulty and related reproducibility in an arthroscopic environment, and repair stability (in the suture-bone contact area). About cyclic performance several authors have conceived tests set up with the aim of simulating a real environment in dynamic load conditions. The aim of this study is to monitor gap formation in a cyclic test set up. Methods The performance (measured as gap formation) has been monitored as a function of bone density to verify the effect of the latter. The test blocks have been shaped by sawbones® test bricks (Malmo, Sweden) of different densities and the following values have been tested: 10, 15, 20, 30, 40 pcf. Findings The comparison has been made between the two groups, traditional transosseous and new approach with an interposed device. Regarding the traditional transosseous approach in a 10 pcf environment not even the first loading cycle was completed, the whole bone bridge was destroyed in the first loading ramp and no further loading capability was present in the repair. By increasing the block density the surface damage in the suture-block contact decreased. Interpretation With this work it has been demonstrated how the traditional transosseous approach is strongly influenced by the bone quality up to the point where, in certain conditions, a safe and reliable repair is not guaranteed.
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