Antonios Dratzidis

Biomechanical Properties of Suture Anchor Repair Compared With Transosseous Sutures in Patellar Tendon Ruptures A Cadaveric Study

Background: Ruptures of the patellar tendon are debilitating injuries requiring surgical repair. Reliable data about the most appropriate suture technique and suture material are missing. The standard procedure consists of refixing the tendon with sutures in transpatellar tunnels, sometimes combined with augmentation. Hypothesis: Suture anchors provide at least equal results concerning gap formation during cyclic loading and ultimate failure load compared with transosseous suture repair. Study Design: Controlled laboratory study. Methods: A total of 30 human cadaveric patellar tendons underwent tenotomy followed by repair with 5.5-mm titanium suture anchors, 5.5-mm resorbable hydroxyapatite suture anchors, or transpatellar suture tunnels with No. 2 Ultrabraid and the Krackow whipstitch technique. Biomechanical analysis included pretensioning the constructs at 20 N for 30 seconds and then cyclic loading of 250 cycles between 20 and 100 N at 1 Hz in a servohydraulic testing machine with measurement of elongation. After this, ultimate failure load and failure mode analysis was performed. Results: Compared with transosseous sutures, tendon repairs with suture anchors yielded significantly less gap formation during cyclic loading (P < .05) and resisted significantly higher ultimate failure loads (P < .05). Common failure mode was pullout of the eyelet within the suture anchor in the hydroxyapatite anchor group and rupture of the suture in the titanium anchor group and—at lower load to failure—in the transosseous group. Conclusion: Patellar tendon repair with suture anchors yields significantly better biomechanical results than repair with the commonly applied transosseous sutures. Clinical Relevance: These findings may be of relevance for future clinical treatment of patellar tendon ruptures. Randomized controlled clinical trials comparing suture anchors to transosseous suture repair are desirable.

The biomechanics of biodegradable versus titanium interference screw fixation for anterior cruciate ligament augmentation and reconstruction

PurposeThe ligament augmentation and reconstruction system (LARS) is one of the options available for anterior cruciate ligament (ACL) reconstruction. To date, however, there are no published data regarding the biomechanical properties of LARS fixation for ACL reconstruction. The aim of this study was to investigate the biomechanical properties of various LARS interference-screw fixations.MethodsA total of 100 LARS ligaments were fixed in porcine femurs with five different interference screws (four biodegradable screws and one titanium interference screw) introduced from inside-out or extra-articularly outside-in. Each group consisted of ten specimens. The constructs were cyclically stretched and subsequently loaded until failure. We evaluated the maximum load before failure, elongation during cyclic loading, stiffness, and failure mode.ResultsElongation during cyclical loading for all devices tested was significantly larger between the first and 20th cycles than between the 20th and 500th cycles (p < 0.05). Maximum failure load was not significantly lower for the biodegradable screws than for the titanium screws (p > 0.05). All specimens failed because of ligament pull-out from the bony tunnel.ConclusionsOur findings suggest that biomechanical secure fixation of the LARS for ACL reconstruction can be achieved using either biodegradable or titanium interference screws. The stability of fixation is independent of the approach, type of investigation, and type of fixation (extra-articular outside-in or intra-articular inside-out).

Biomechanical evaluation of the simple cinch stitch for arthroscopic rotator cuff repair

BACKGROUND The tissue-suture interface is described as the most vulnerable and susceptible area in the muscle-tendon-bone construction of arthroscopic rotator cuff repair. Various stitching techniques have been described to enhance the strength, fixation and stability of the repair, but technical and biomechanical challenges remain. Purpose was to examine the biomechanical properties of the simple cinch stitch in comparison to other stitches commonly used for rotator cuff repair. METHODS Infraspinatus tendons were harvested from sheep and split in half. The tendons were randomized into five different stitch configuration groups for biomechanical testing: simple stitch; horizontal stitch; FiberChain®; simple cinch stitch; and modified Mason-Allen stitch. Each specimen was first cyclically loaded on a universal materials testing machine under force control from 5 to 30N at 0.25Hz for twenty cycles. Then, each specimen was loaded to failure under displacement control at a rate of 1mm/s. Cyclic elongation, peak-to-peak displacement and ultimate tensile load were measured. The type of failure was recorded. FINDINGS No differences in cyclic elongation or peak-to-peak displacement were seen between stitch configurations. In the load-to-failure test, the simple cinch stitch demonstrated significantly higher ultimate load than the simple and the horizontal stitch configurations. The comparison to the FiberChain® Suture revealed no statistical significant differences. The FiberChain® Suture demonstrated significantly higher ultimate load than the simple stitch. No statistical significance could be demonstrated in comparison to the horizontal stitch or the simple cinch stitch. The ultimate tensile load of the modified Mason-Allen stitch was significantly higher than that of the other stitch configurations. INTERPRETATION The simple cinch stitch has an ultimate tensile load comparable to the FiberChain® suture and is superior to the simple stitch and the horizontal stitch. The major advantage of the simple cinch technique is that it is possible to perform the stitch entirely arthroscopically, without the need to perforate the tissue a second time or to use special suture materials. STUDY DESIGN Controlled laboratory study.

A Novel Pull-Press Fixation: Improved Mechanical Performance With Any Graft Without Hardware

A lot of biomechanical research has been conducted in the field of reconstruction of the anterior cruciate ligament. Nonetheless, in times of cost efficiency, we are bound to develop new techniques for implant-free reconstruction and improve the biomechanical properties of such. Press-fit techniques are commonly used and show reasonable results without the use of any hardware. The pull-press fixation is a promising new technique for tibial anterior cruciate ligament fixation that could offer a lot of advantages and is simple to perform. It is applicable for hamstring, patella, and quadriceps grafts. It has the advantages of a press fixation close to the joint without the need of harvesting a bone cylinder and therefore reduces the intraoperative trauma and has no risk of bone necrosis. Like a press fixation, it occupies the articular part of the bone tunnel and prevents synovial fluid from entering the drill hole. As the graft is blocking the articular entrance, it may also reduce the windshield-wiper effect and postoperative joint effusion. The pull-press fixation fosters the tendon-to-bone healing by applying pressure to the bone tunnel wall. Not using any hardware for fixation of any graft significantly reduces expenses of the procedure and facilitates any further revision surgery. Because no hardware is used, artifacts in postoperative magnetic resonance imaging are less likely to occur.