Rotator cuff repair. A biomechanical comparison of three techniques

BACKGROUND: The most common complication of rotator cuff repair is structural failure at the repair site. A single-layer repair does not adequately reproduce the anatomic insertion and may not optimize fixation strength. HYPOTHESIS: A double-layer rotator cuff repair will have greater initial fixation strength than a single-layer repair. STUDY DESIGN: Controlled laboratory study. METHODS: Twelve fresh-frozen matched pairs of cadaveric shoulders were repaired by using dual-site fixation with both suture anchors and transosseous tunnels on one side (technique 1). Fixation was achieved by using suture anchors with horizontal mattress sutures and bone tunnels with modified Mason-Allen sutures. Half of the contralateral matched shoulders underwent fixation with suture anchors and simple sutures to simulate commonly used arthroscopic methods (technique 2) and, in the rest, fixation was achieved by using transosseous tunnels and modified Mason-Allen sutures (technique 3). Repaired specimens then underwent cyclic loading at physiologic rates and loads. The number of cycles to failure, which was defined as a 1-cm gap at the repair site, was then recorded. An arbitrary cut-off point of 5000 cycles was chosen. RESULTS: The mean number of cycles to failure with technique 1 (3694 +/- 1980 cycles) was significantly greater than that with either technique 2 (1414 +/- 1888 cycles) or technique 3 (528 +/- 683 cycles). Failure was predominantly through bone. CONCLUSIONS: The initial fixation strength of our double-layer repair exceeds that of isolated single-layer repairs with either suture anchors or transosseous tunnels.     

Pullout strength of suture anchors in comparison with transosseous sutures for rotator cuff repair

Suture anchors are increasingly gaining importance in rotator cuff surgery. This means they will be gradually replacing transosseous sutures. The purpose of this study was to compare the stability of transosseous sutures with different suture anchors with regard to their pullout strength depending on bone density. By means of bone densitometry (CT scans), two groups of human humeral head specimens were determined: a healthy and a osteopenic bone group. Following anchor systems were being tested: SPIRALOK™ 5.0 mm (resorbable, DePuy Mitek), Super Revo 5 mm (titanium, Linvatec), UltraSorb (resorbable, Linvatec) and the double U-sutures with Orthocord™ USP 2 (partly resorbable, DePuy Mitek) and Ethibond Excel 2 (non-resorbable, Ethicon). The suture anchors/double U-sutures were inserted in the greater tuberosity 12 times. An electromechanical testing machine was used for cyclic loading with power increasing in stages. We recorded the ultimate failure loads, the system displacements and the modes of failure. The suture anchors tended to bring about higher ultimate failure loads than the transosseous double U-sutures. This difference was significant in the comparison of the Ethibond suture and the SPIRALOK 5.0 mm—both in healthy and osteopenic bone. Both the suture materials and the SPIRALOK 5.0 mm showed a significant difference in pullout strength on either healthy or osteopenic bone; the titanium anchor SuperRevo 5 mm and the tilting anchor UltraSorb did not show any significant difference in healthy or osteopenic bone. There was no significant difference concerning system displacement (healthy and osteopenic bone) between the five anchor systems tested. The pullout strength of transosseous sutures is neither on healthy nor on osteopenic bone higher than that of suture anchors. Therefore, even osteopenic bone does not constitute a valid reason for the surgeon to perform open surgery by means of transosseous sutures. The choice of sutures in osteopenic bone is of little consequence anyway since it is mostly the bone itself which is the limiting factor.     

Biomechanische Aspekte der Rotatorenmanschettennaht: Einfluss von Nahtmaterial,Knotentechnik und Nahttechnik auf die Primärstabilität

BackgroundThe treatment of Rotator cuff (RC) tears has made significant chances in the last decades. Due to arthroscopic procedures new material and technologies have been developed. Up to now, attention was focused mainly on the development of material with higher mechanical strength, stronger suture material, or improving of suturing and knotting. The present study focusses on all different aspects together which influence the biomechanical stability of rotator cuff tear reconstructions.Materials and MethodsDiverse kinds of suture anchors (different designs and materials) and transosseous sutures were tested biomechanically in human humeral specimen. Arthroscopic sliding and nonsliding-nodes were tested with conventional (Ethibond and PDS) and new UHMWPE sutures for biomechanical features. Additionally we tested three arthroscopic suture techniques (single-, matress-, arthroscopic Mason Allen- stitch) with above mentioned materials in human RC tendons. All tests were performed under cyclic loading on the Zwick universal Testing machine. The maximum failure rate, the clinical failure rate at 3 mm irreversible expension and the failure mechanism were evaluated.ResultsBetween the different suture anchors were found significantly differences only in healthy human humeral specimen. In osteoporotic bone all different suture anchors were comparable with failure values less than 200 N. Subcortical fixed suture anchors tend to have a higher stability than in cancellous bone fixed suture anchors. Transosseos sutures showed no benefits in osteoporotic bone. With up to 300 N the UHMWPE sutures had a significantly higher strength than Ethibond / PDS sutures. Though, depending on the node type, even UHMWPE sutures showed a relevant elongation at values between 100-200 N. The lowest biomechanical strength showed the tendon-suture construct. Even though the Mason Allen stitch with UHMWPE sutures showed the highest stability (>200 N) clinical failure appeared at about 100 N. The weakest link in the failure of RC repair seems to be the suture-tendon interface. Even when using UHMWPE sutures and a biomechanical stable suture technique clinical failure was observed at approx. 100 N.ConclusionsThese results suggest that the development of suture anchors with rising diameter seems to be irrelevant. Rather, the technical development should focus on small anchors with a subcortical fixation and therefore better biomechanical stability. Especially in revision cases this seems to be relevant. Post-operative treatment should be moderate because clinical failure can appear from only 100 N of load.Level of evidenceLevel IV.     

Distal biceps tendon repair: a biomechanical comparison of intact tendon and 2 repair techniques

BACKGROUND: A variety of techniques have been described for distal biceps tendon reattachment-bone tunnel with transosseous sutures, suture anchors, and interference screw techniques. HYPOTHESIS: There will be no significant difference between the mean failure strength, maximum strength, and stiffness of the intact specimen and repair techniques tested: bone tunnel with transosseous sutures and interference screw. STUDY DESIGN: Controlled laboratory study. METHODS: Nine matched pairs of fresh-frozen human cadaveric elbows were prepared. The intact tendon was pulled from the radial tuberosity; the right and left elbows were randomized to bone tunnels with transosseous sutures or interference screw repair techniques. The repaired specimens were pulled using the same regimen for the intact tendon. Failure strength, maximum strength, and stiffness were measured and compared. RESULTS: The mean failure strength, maximum strength, and stiffness of intact tendons were 204.3 +/- 76.9 N, 221.7 +/- 65.9 N, and 30.1 +/- 12.4 N/mm, respectively; for the interference screw specimens, 178.0 +/- 54.5 N, 192.1 +/- 53.1 N, and 30.4 +/- 9.5 N/mm, respectively; and for the bone tunnel specimens, 124.9 +/- 22.8 N, 206.6 +/- 49.8 N, and 15.9 +/- 5.6 N/mm, respectively. There were no significant differences between measures in the intact and interference screw specimens. Mean failure strength and stiffness of the bone tunnel specimens were significantly lower than those of the intact and interference screw specimens; there was no significant difference between the maximum strengths of the treatments. Interference screw failure occurred abruptly with little plastic deformation in nearly all specimens with the tendon and screw pulling out as a unit, often involving fracture of the radial wall. Two of the bone tunnels failed at the bony bridge; the remainder lost bone-tendon contact as the distal tendon was shredded by the suture. CONCLUSION: The results suggest interference screw fixation repair is nearly as strong and stiff as the intact tendon and stronger than the bone tunnel repair technique. CLINICAL RELEVANCE: The interference screw provides better stiffness and failure strength compared with the bone tunnel technique for distal biceps tendon repair. Given the superior mechanical properties, the interference screw technique is recommended as the treatment of choice for biceps tendon rupture repair.     

Initial fixation strength of flexible all-inside meniscus suture anchors in comparison to conventional suture technique and rigid anchors: biomechanical evaluation of new meniscus refixation systems

BACKGROUND: The newest generation of meniscus repair devices is designed to combine the benefits of the all-inside technique with the biomechanical properties of sutures. HYPOTHESIS: New flexible all-inside suture anchors have better fixation strength than rigid anchors, but there is no difference when compared to conventional horizontal and vertical mattress sutures. STUDY DESIGN: Controlled laboratory study. METHODS: In fresh-frozen bovine menisci, initial fixation strength, stiffness, and failure mode of different meniscus fixation techniques (FastT-Fix, RapidLoc, Meniscus Arrow, horizontal and vertical 2.0 Ethibond sutures) were evaluated in a computer-based materials testing machine at a rate of 12.5 mm/sec. RESULTS: The vertical and horizontal FastT-Fix suture anchors were the strongest devices with regard to pullout strength, with no significant difference compared to the vertical 2-0 Ethibond sutures. Horizontal sutures, Meniscus Arrow, and RapidLoc had significantly lower pullout strength. Vertical and horizontal FastT-Fix suture anchors showed significantly higher stiffness than the other devices. CONCLUSIONS: Biomechanical properties of flexible all-inside meniscus anchors (FastT-Fix) are comparable to conventional vertical suture techniques. Characteristics of the flexible RapidLoc are comparable to rigid anchors (Meniscus Arrow). CLINICAL RELEVANCE: From the biomechanical point of view, flexible all-inside meniscus refixation devices are an alternative to conventional suture techniques and rigid meniscus anchors.     

Hamstring graft fixation in MPFL reconstruction at the patella using a transosseous suture technique

Controversy still exists about fixation methods of a hamstring graft to the patella in case of medial patellofemoral ligament (MPFL) reconstruction. This article presents a surgical technique of hamstring tendon graft fixation to the anatomical MPFL insertion on the patella using transosseous sutures. A superficial bony sulcus is created at the anatomical MPFL insertion site on the medial patellar rim with a bur. A looped hamstring tendon graft is fixed to this superficial sulcus by a pair of nonresorbable transosseous sutures passed across the patella. The retinaculum is sutured on top of the hamstring tendon graft at the level of the patella for additional fixation. The technique avoids bone tunnels as well as hardware at the patella. It reduces the risk of intraoperative or postoperative patella fracture or implant-related complications. The stable transosseous fixation technique allows for early rehabilitation.     

Biomechanical evaluation of a new technique for rotator cuff repair

BACKGROUND: In recent studies, investigators have used a cyclic loading model to investigate the efficacy of rotator cuff fixation modalities. HYPOTHESIS: A bioabsorbable poly-D-lactic acid screw and toothed washer implant will provide more stable fixation of rotator cuff repairs than standard suture anchor techniques. STUDY DESIGN: Controlled laboratory study. METHODS: Forty bovine shoulders (ages 3 to 6 months) had 1 x 2 cm defects created in the infraspinatus tendon. There were five repair groups (eight specimens per group) consisting of either two screw and washer implants or two suture anchors. Four suture techniques were tested: single-loaded anchors with simple sutures, double-loaded anchors with simple sutures, single-loaded anchors with horizontal mattress sutures, or single-loaded anchors with modified Mason-Allen sutures. Repairs were loaded at 5-second cycles from 10 to 180 N with use of a hydraulic testing machine. The number of cycles to gap formation of 5 and 10 mm was recorded. RESULTS: Gap formation of 5 and 10 mm occurred significantly later for the screw repair group than for any of the suture anchor groups. There was no significant difference between suture groups. CONCLUSIONS: The bioabsorbable screw and washer provided more stable fixation than suture anchor techniques under isometric cyclic loading conditions. Clinical Relevance: This is a time-zero study of implant performance. The results indicate that the implant may decrease clinical failures in the early postoperative period under standard rehabilitation protocols.     

Arthroscopic transosseous (anchorless) rotator cuff repair

The traditional open transosseous rotator cuff repair gives excellent results for the fixation of tendon to bone and has represented the gold standard for rotator cuff surgery with excellent long-term results. In the last few years, different arthroscopic techniques using suture anchors have been developed to increase the tendon-bone contact area in an attempt to reconstitute a more anatomic configuration of the rotator cuff footprint while providing a better environment for tendon healing. However, the anchor-based techniques have still not replicated the traditional open transosseous repair. A surgical technique that allows surgeons to perform a standardized arthroscopic transosseous (anchor free) repair of rotator cuff tears using a new disposable device is described. With this system, it is possible to perform a transosseous technique in a reproducible fashion. This novel technique combines the clinical advantages of minimally invasive arthroscopic surgery and the biomechanical advantages of open transosseous procedures. LEVEL OF EVIDENCE: V.     

New sutures and suture anchors in sports medicine

Arthroscopic surgery requires appropriate surgical implants for effective fixation of tendons and ligaments to bone. Biodegradable suture anchors are being used with increasing frequency for various procedures in sports medicine. As companions to these biodegradable suture anchors, new sutures have been developed which possess greater strength and different material properties from the conventional braided polyester suture. Biodegradable polymers currently found in sutures and suture anchors include poly-L-lactic acid, poly-D, L lactic acid, polydioxanone, polyglycolic acid and their copolymers. Suture anchors are now available preloaded with a choice of conventional braided polyester sutures or some version of ultrahigh molecular weight polyethylene ("super") sutures. Most new suture anchors come with 2 sutures. The manner in which these sutures are attached to the anchor varies and may consist of 2 separate eyelets or 2 slots either parallel to one another or at different angles to one another. Some anchors have a very large single eyelet that allows for 2 or more sutures.     

Improving the biomechanical properties of the T-fix using oblique direction: in vitro study on bovine menisci

This study compared pullout strengths of the T-fix device versus horizontal suture toward improving T-fix biomechanical properties. Twenty bovine medial menisci were used for this study. Four groups were tested and mean tearing stress were obtained. In group 1 a standard T-fix suture was performed (50.2+/-4.2 N); in group 2 horizontal mattress sutures were placed in the meniscus using 2-0 vicryl (54.6+/-4.2 N); in group 3 three T-fix suture anchors were placed: the central suture a double suture anchor and those on either side single suture anchors, resulting in two horizontal sutures (61.8+/-3.8 N); in group 4 we modified the technique used in group 3. The double suture anchor was placed the incision, at a 30 degrees angle oblique to the horizontal (71.0+/-5.9 N). There was a statistically significant difference between groups 3 and 4 but not between groups 1 and 2. In conclusion: Using a T-fix suture anchor in the standard technique has similar biomechanical properties to the horizontal mattress suture. To improve the tensile properties of the T-fix suture a double T-fix suture anchor should be used obliquely to the other two single T-fix sutures on either side.     

Contact area, contact pressure, and pressure patterns of the tendon-bone interface after rotator cuff repair

BACKGROUND: The contact pressure and contact area at the tendon-bone interface after the most commonly used rotator cuff repair methods have not been investigated. HYPOTHESIS: There are no significant differences among the transosseous, the single-row suture anchor, and the double-row suture anchor techniques in terms of contact pressure, contact area, and pressure patterns at the tendon-bone interface. STUDY DESIGN: Controlled laboratory study. METHODS: After creating a full-thickness supraspinatus tendon tear in 10 cadaveric shoulder specimens, we inserted pressure-sensitive film between the tendon stump and the bone, and we repaired the tear by (1) transosseous, (2) single-row suture anchor, and (3) double-row suture anchor techniques. RESULTS: The contact area of the double-row technique was 42% greater than that of the transosseous technique (P < .0001) and 60% greater than that of the single-row technique. The contact area of the transosseous technique was 31% greater than that of the single-row technique (P = .0015). The average pressures of the single-row and double-row techniques were 18% (P = .014) and 16% (P = .03) greater, respectively, than that of the transosseous technique, but there was no significant difference between the single-row and double-row techniques (P = .915). CONCLUSIONS: The double-row technique produced the greatest contact area and the second-highest contact pressure, whereas the single-row technique created the highest contact pressure and the least contact area. The transosseous technique produced the second-greatest contact area and the least contact pressure. CLINICAL RELEVANCE: The double-row suture anchor technique and the transosseous technique may provide a better environment for tendon healing.     

Tendon-bone interface motion in transosseous suture and suture anchor rotator cuff repair techniques

BACKGROUND: Although many studies involving rotator cuff repair fixation have focused on ultimate fixation strength and ability to restore the tendon's native footprint, no studies have characterized the stability of the repair with regard to motion between the tendon and repair site footprint. HYPOTHESIS: Suture anchor fixation for rotator cuff repair has greater interface motion between tendon and bone than does transosseous suture fixation. STUDY DESIGN: Controlled laboratory study. METHODS: Twelve fresh-frozen human cadaveric shoulders were tested in a custom device to position the shoulder in internal and external rotations with simulated supraspinatus muscle loading. Tendon motion relative to the insertional footprint on the greater tuberosity was determined optically using a digital camera rigidly connected to the humerus, with the humerus positioned at 60 degrees of internal rotation and 60 degrees of external rotation. Testing was performed for the intact tendon, a complete supraspinatus tear, a suture anchor repair, and a transosseous tunnel repair. RESULTS: Difference in tendon-bone interface motion when compared with the intact tendon was 7.14 +/- 3.72 mm for the torn rotator cuff condition, 2.35 +/- 1.26 mm for the suture anchor repair, and 0.02 +/- 1.18 mm for the transosseous suture repair. The transosseous suture repair demonstrated significantly less motion when compared with the torn rotator cuff and suture anchor repair conditions (P < .05). CONCLUSION: Transosseous suture repair compared with suture anchor repair demonstrated superior tendon fixation with reduced motion at the tendon-to-tuberosity interface. CLINICAL RELEVANCE: Development of new fixation techniques for arthroscopic and open rotator cuff repairs should attempt to minimize interface motion of the tendon relative to the tuberosity.     

Stress distribution in the supraspinatus tendon after tendon repair: suture anchors versus transosseous suture fixation

BACKGROUND: The stress concentration at the site of supraspinatus tendon repair, either by suture anchor fixation or by transosseous suture fixation, has not been fully clarified. HYPOTHESIS: Suture anchor fixation showed higher stress concentrations in the tendon than did transosseous suture fixation. STUDY DESIGN: Controlled laboratory study. METHODS: Three finite element models were developed based on a previously published model of normal supraspinatus tendon (0 degrees abduction). Single-row fixation, double-row fixation, and transosseous suture fixation were simulated. A tensile force was applied to the proximal end of the supraspinatus tendon to simulate its contraction force. RESULTS: In the single-row model, the stress appeared from the site of the anchor and extended into the proximal tendon. The highest stress concentration was observed on the bursal surface of the tendon. The double-row model showed a similar pattern to the single-row model except that the stress concentration was observed only around the medial anchor. In the transosseous model, the stress appeared from the attachment site to a bony trough, which extended proximally into the tendon substance. No significant stress concentration was observed inside the tendon. CONCLUSION: Both single-row and double-row fixations showed higher stress concentration inside the tendon than did transosseous suture fixation. CLINICAL RELEVANCE: A high stress concentration might be a cause of the rerupture often observed after arthroscopic cuff repair using suture anchors.     

The use of suture anchors in repair of the ruptured patellar tendon: a biomechanical study

BACKGROUND: Rupture of the patellar tendon is a disabling injury that usually requires surgical treatment. The standard method of repair involves placing suture loops through transpatellar tunnels. The use of suture anchors in patellar tendon repair has not been previously described. HYPOTHESIS: No difference exists in the amount of gap formation during cyclic loading or in ultimate load-to-failure strength between repairs performed with anchors and those performed with 2 types of transpatellar sutures. STUDY DESIGN: Controlled laboratory study. METHODS: Six matched pairs of cadaveric knees were tested in a custom biomechanical apparatus based on an established model. Repairs were performed using either suture anchors with No. 2 FiberWire or transpatellar suture tunnels using 2 different types of suture-No. 5 Ethibond and No. 2 FiberWire. Gap formation across the repair site during 250 cycles of extension as well as ramp-up load to failure were measured for each repair. RESULTS: The mean total gap formation across the repair site at 250 cycles was 4.1 +/- 1.9 mm for the suture anchor group, 6.7 +/- 1.8 mm for the FiberWire tunnel group, and 8.5 +/- 2.7 mm for the Ethibond tunnel group. Mean load to failure was 779 +/- 183 N, 730 +/- 83 N, and 763 +/- 231 N, respectively. CONCLUSION: Significantly less gap formation throughout 250 cycles (P = .009) and no difference in load to failure occurred with patellar tendon repairs performed with suture anchors as compared with repairs performed with transpatellar tunnels. CLINICAL RELEVANCE: The newly described method, using suture anchors for repair of patellar tendon ruptures, may be clinically equal or superior to the established method of using transpatellar tunnels.     

Cyclic testing of flexible all-inside meniscus suture anchors: biomechanical analysis

BACKGROUND: Flexible meniscus repair devices are designed to combine the benefits of rigid all-inside meniscus anchors with the biomechanical properties of sutures. HYPOTHESIS: Stiffness and pull-out strength of flexible all-inside suture anchors and conventional sutures under cyclic loading conditions will be comparable. STUDY DESIGN: Controlled laboratory study. METHODS: In 50 fresh frozen bovine menisci, artificial meniscus lesions were repaired with different meniscus fixation techniques: horizontal and vertical FasT-Fix, RapidLoc, and horizontal and vertical 2-0 Ethibond sutures. The specimens were cycled 1000 times between 5 and 20 N and then loaded to failure. RESULTS: All devices survived the cyclic loading protocol. There was no significant difference in the displacement between all repair techniques tested (horizontal FasT-Fix, 6.23 mm; vertical FasT-Fix, 5.34 mm; RapidLoc, 6.84 mm; horizontal 2-0 Ethibond, 6.03 mm; vertical 2-0 Ethibond, 5.61 mm (P > .05). Vertical and horizontal FasT-Fix suture anchors had a significantly higher stiffness and pull-out strength (94.1 N and 80.8 N, respectively) than did horizontal sutures (50.2 N) and RapidLoc devices (30.3 N) (P > .05). CONCLUSIONS: In this study, flexible all-inside meniscus anchors (FasT-Fix) had higher pull-out strength than did conventional vertical suture techniques. Biomechanical characteristics of the flexible RapidLoc are comparable to those of horizontal sutures. Clinical Relevance: Flexible all-inside meniscus repair devices are an alternative to conventional suture techniques.     

Biomechanical evaluation of knotless anterior and posterior Bankart repairs

Purpose

The value of modern tape-like suture materials and the influence of the number of anchors inserted for arthroscopic Bankart repairs compared to the intact state have yet to be investigated. It was hypothesised: (1) suture-tape repairs will show higher biomechanical strength than common suture repairs, (2) four anchors will be stronger than three, and (3) the strength of the native capsulolabral complex will be greater than repairs.

Methods

Six matched-paired cadaveric shoulders received Bankart lesions/reconstructions and three underwent intact state testing. Anteroinferior repairs compared suture and suture-tape repairs using three anchors, while posteroinferior repairs compared three and four suture anchors using common sutures. An established testing protocol was run for biomechanical testing.

Results

There was no significant difference in the maximum loads, loads at 2 mm displacement, stiffness or energy between repair groups or between repairs and the intact state (n.s.). However, failure modes were different: 16/24 (66.7 %) of the repair groups showed glenoid labrum detachment compared to 2/12 (16.7 %) within the intact state group (P = 0.012).

Conclusions

While biomechanical parameters of repairs and intact states showed equivalence, failure-mode analysis reaffirms previous findings that capsulolabrum complex refixation is weaker than the native attachment. Therefore, in daily clinical practice, type of suture is secondary and insertion of a fourth anchor will be unlikely to add strength but may confer additional risk and cost.     

Biomechanical comparison of a single-row versus double-row suture anchor technique for rotator cuff repair

BACKGROUND: Reestablishment of the native footprint during rotator cuff repair has been suggested as an important criterion for optimizing healing potential and fixation strength. HYPOTHESIS: A double-row rotator cuff footprint repair will demonstrate superior biomechanical properties compared with a single-row repair. STUDY DESIGN: Controlled laboratory study. METHODS: In 9 matched pairs of fresh-frozen cadaveric shoulders, the supraspinatus tendon from 1 shoulder was repaired with a double-row suture anchor technique: 2 medial anchors with horizontal mattress sutures and 2 lateral anchors with simple sutures. The tendon from the contralateral shoulder was repaired using a single lateral row of 2 anchors with simple sutures. Each specimen underwent cyclic loading from 10 to 180 N for 200 cycles, followed by tensile testing to failure. Gap formation and strain over the footprint area were measured using a video digitizing system; stiffness and failure load were determined from testing machine data. RESULTS: Gap formation for the double-row repair was significantly smaller (P < .05) when compared with the single-row repair for the first cycle (1.67 +/- 0.75 mm vs 3.10 +/- 1.67 mm, respectively) and the last cycle (3.58 +/- 2.59 mm vs 7.64 +/- 3.74 mm, respectively). The initial strain over the footprint area for the double-row repair was nearly one third (P < .05) the strain of the single-row repair. Adding a medial row of anchors increased the stiffness of the repair by 46% and the ultimate failure load by 48% (P < .05). CONCLUSION: Footprint reconstruction of the rotator cuff using a double-row repair improved initial strength and stiffness and decreased gap formation and strain over the footprint when compared with a single-row repair. CLINICAL RELEVANCE: To achieve maximal initial fixation strength and minimal gap formation for rotator cuff repair, reconstructing the footprint attachment with 2 rows of suture anchors should be considered.     

Minimally invasive endoscopic reconstruction technique of acute AC-joint dislocations: a cadaver study

The treatment of acute Rockwood type III AC-joint dislocations is controversial. Problems related to open surgery are soft tissue healing, residual instability and the necessity of hardware removal. After non-operative therapy the cosmetic result may be problematic and in some cases symptomatic instabilities occur. The goal of the present cadaver study was to develop a new, minimally invasive technique for acute AC-joint reconstructions and to analyse its potential risk for neurovascular injuries. The surgical technique was based on an arthroscopically assisted reconstruction of the coracoclavicular ligaments with a suture anchor (Arthrex, Naples, FL, USA) and a supplemental stabilization of the AC-joint capsule with a suture cerclage (Fibre Wire 2, Arthrex) performed on ten cadaveric shoulder specimens. After surgery all specimens were dissected to analyse the anatomy of the coracoclavicular ligament complex, the position of anchors and sutures and to measure the distance to the neurovascular structures at risk. The supraspinatus muscle was never injured by the Neviaser approach. The insertion of the suture anchors never failed, resulting in a secure and reproducible anchor position. The mean distance between the coracoid and suprascapular nerve was 1.8 cm (1.5–2.2), between the coracoid and the suprascapular artery 1.5 cm (1.3–1.9). These structures were never injured. The resulting force vector of the suture located between the anchor and the drill hole was close to the anatomic force vector of the coracoclavicular ligament complex. The suture cerclage was always correctly positioned. The presented technique is at minimal risk for the surrounding neurovascular structures and allows for a minimally invasive and anatomically correct reconstruction of the AC-joint. Further biomechanical analysis is needed to evaluate the strength of the reconstruction technique. The proposed technique might be a reasonable alternative to existing invasive techniques of open reconstruction of acute type III AC-joint dislocations in high-demand patients.     

Arthroscopic rotator interval closure: effect of sutures on glenohumeral motion and anterior-posterior translation

BACKGROUND: The effect of arthroscopic rotator interval closure on glenohumeral motion and translation is not well understood, nor is the ideal location or number of sutures required for closure. HYPOTHESIS: The number of arthroscopic rotator interval closure sutures and their placement will have a significant effect on glenohumeral range of motion and anterior-posterior translation. STUDY DESIGN: Controlled laboratory study. METHODS: Using a custom testing apparatus, the authors measured range of motion in 12 fresh-frozen cadaveric shoulders; anterior-posterior translation in adduction and neutral rotation was measured in 9. Specimens were initially tested without sutures and then tested after 3 interval closures using a random sequence of (1) an isolated medial suture at the level of the glenoid, (2) an isolated lateral suture 1 cm lateral to the glenoid, or (3) both sutures followed by removal of all sutures. RESULTS: Analysis of variance demonstrated that interval closure had a significant effect on decreasing flexion (mean, 6 degrees), external rotation (mean, 10 degrees), and anterior translation (mean, 3 mm) of the adducted shoulder. There was no significant difference between the 3 interval closures in any of the tests. CONCLUSION: Arthroscopic interval closure produced significant decreases in range of motion and anterior-posterior translation. The effects of single lateral or medial suture closures were similar to the use of 2 sutures. CLINICAL RELEVANCE: This study suggests that the initial effect of arthroscopic rotator interval closure on anterior translation of the shoulder will be similar whether 1 or 2 sutures are used. In vivo studies are necessary to determine if the effect of these 2 methods would be the same over time.     

Tendon-to-bone pressure distributions at a repaired rotator cuff footprint using transosseous suture and suture anchor fixation techniques

BACKGROUND: Interface contact pressure between the tendon and bone has been shown to influence healing. This study evaluates the interface pressure of the rotator cuff tendon to the greater tuberosity for different rotator cuff repair techniques. HYPOTHESIS: The transosseous tunnel rotator cuff repair technique provides larger pressure distributions over a defined insertion footprint than do suture anchor techniques. STUDY DESIGN: Controlled laboratory study. METHODS: Simulated rotator cuff tears over a 1 x 2-cm infraspinatus insertion footprint were created in 25 bovine shoulders. A transosseous tunnel simple suture technique (n = 8), suture anchor simple technique (n = 9), and suture anchor mattress technique (n = 8) were used for repair. Pressurized contact areas and mean pressures of the repaired tendon against the tuberosity were determined using pressure-sensitive film placed between the tendon and the tuberosity. RESULTS: The mean contact area between the tendon and tuberosity insertion footprint was significantly greater for the transosseous technique (67.7 +/- 5.8 mm(2)) compared with the suture anchor simple (34.1 +/- 9.4 mm(2)) and suture anchor mattress (26.0 +/- 5.3 mm(2)) techniques (P < .05). The mean interface pressure exerted over the footprint by the tendon was also greater for the transosseous technique (0.32 +/- 0.05 MPa) compared with the suture anchor simple (0.26 +/- 0.04 MPa) and suture anchor mattress (0.24 +/- 0.02 MPa) techniques (P < .05). CONCLUSION: The transosseous tunnel rotator cuff repair technique creates significantly more contact and greater overall pressure distribution over a defined footprint when compared with suture anchor techniques. CLINICAL RELEVANCE: Stronger and faster rotator cuff healing may be expected when beneficial pressure distributions exist between the repaired rotator cuff and its insertion footprint. Tendon-to-tuberosity pressure and contact characteristics should be considered in the development of improved open and arthroscopic rotator cuff repair techniques.