腘绳肌腱结嵌压固定法重建交叉韧带的临床应用与生物力学研究

目的探讨腘绳肌腱结嵌压固定法重建交叉韧带的可行性。方法对52例陈旧性前、后交叉韧带损伤患者在关节镜下行双股腘绳肌腱中间打结,嵌入瓶颈状股骨隧道内固定,胫骨端采用肌腱编织缝合在骨桥上打结固定,重建交叉韧带。其中前交叉韧带25例,前、后十字韧带同时重建15例,后交叉韧带12例。生物力学实验采用猪膝关节。股骨端固定分为肌腱结嵌入组(n=13)和骨髌腱骨(B PT B)介面螺钉固定组(B PT B介面钉组,n=11)。胫骨端固定分为肌腱编织缝合线在骨桥打结组(n=7)、肌腱编织缝合介面螺钉组(n=8)。进行最大拔出强度、最大位移和固定刚度等力学实验。结果术后随访49例,平均14 6个月,Lanchman试验阴性46例,阳性3例。术后Lysholm评分由术前56 7分提高到92 8分。按膝关节疗效评定标准,优46例,良3例。生物力学实验最大拔出强度肌腱结嵌入组高于B PT B介面钉组;固定刚度肌腱结嵌入组小于B PT B介面钉组;最大位移肌腱结嵌入组大于B PT B介面钉组。胫骨端固定抗拉强度和刚度骨桥打结组优于介面螺钉组。结论腘绳肌腱结嵌压固定重建交叉韧带生物力学抗拉强度能满足生理需求,方法可行;可克服位移因素,降低韧带松弛率,提高疗效。     

Effect of pilot-hole size on the pullout strength of flexor digitorum longus transfer fixed with a bioabsorbable screw

BACKGROUND: Fixation of tendon transfers with a bioabsorbable interference-fit screw has several advantages over other fixation methods: decreased dissection, operative time, and blood loss; preservation of tendon length; no interference with radiographic studies; no need for implant removal; and no barrier to revision surgery. Whether strength of fixation is affected by the size of the pilot hole has not been established. The purpose of this study was to determine the effect of pilot hole size on the pullout strength of a flexor digitorum longus (FDL) tendon secured into a bone analog using a 5.5-mm bioabsorbable screw. METHODS: Thirty FDL tendons were harvested from 15 cadaver specimens and secured into predrilled 4 x 4 x 4 cm bone cubes with a 5.5-mm Arthrex bioabsorbable screw (Arthrex, Naples, FL). The use of bone analog foam cubes ensured consistent porosity at the insertion site, eliminating the variations associated with varying bone densities of cadaver specimens. Pilot hole sizes studied were 5.0 mm, 5.5 mm, and 6.0 mm. Pullout tests were done with an servohydraulic testing frame (MTS, Eden Prairie, MN). RESULTS: There was no significant difference (p = 0.4) between the pullout forces and stresses among the three pilot hole sizes. All specimens failed at the interface between the FDL and the bioabsorbable screw. In the 6.0-mm pilot hole group, there was a trend for increased pullout strength with increased tendon size. CONCLUSIONS: With a bioabsorbable 5.5-mm screw used for FDL transfer, a pilot hole the same size or a half millimeter larger or smaller than the screw had no statistically significant effect on the strength of the construct, even with tendons of different sizes.     

Tenodesis of the long head of biceps brachii: cyclic testing of five methods of fixation in a porcine model

For pathologies of the long head of the biceps brachii, various surgical treatment options have been described, ranging from tenotomy to different open and arthroscopic techniques for tenodesis. We analyzed the biomechanical properties of 5 widely used operative techniques for tenodesis of the long head of the biceps brachii: an interference screw (7 x 23-mm Arthrex BioTenodesis screw), a suture anchor (5 x 15-mm Arthrex BioCorkscrew), a ligament washer, the keyhole technique, and the bone tunnel technique. Ten porcine humeri for each technique were used to evaluate the ultimate failure load and cyclic displacement. Tenodesis with the interference screw showed a significantly greater ultimate failure load compared with every other technique (480.9 +/- 116.5 N, P < .005) and the least displacement after 200 cycles, significantly less in comparison to the keyhole and bone tunnel techniques (4.28 +/- 1.44 mm, P < .05). Interference screw fixation has superior biomechanical properties with respect to cyclic displacement and primary fixation strength.     

Interference screw position and hamstring graft location for anterior cruciate ligament reconstruction

Anterior cruciate ligament reconstruction with hamstring tendon graft and interference screw fixation has recently been considered. Concerns for the use of interference screws with soft tissue grafts include damage to the graft during screw insertion, decreased fixation strength, and a decrease in the bone-tendon contact area for healing within the tunnel when the screw is placed in an eccentric position. This last concern could be addressed by placing the interference screw centrally between the four limbs of the hamstring graft. The purpose of this study was to determine the mode of failure, the pullout force, and graft slippage before graft fixation failure of hamstring tendons fixed with an interference screw positioned eccentrically in relation to the hamstring tendons verses an interference screw positioned centrally between the four graft limbs. The semitendinosus and gracilis tendons were harvested from six, fresh cadaveric specimens. Each tendon was divided into two segments of equal length. Both the semitendinosus and gracilis tendon segments were looped to form four strands. The specimens were then fixed with a bioabsorbable interference screw in the two different positions and pulled from a standardized polyurethane foam. All tendons in both groups failed by pulling out from between the interference screw and tunnel, regardless of the screw position. No tendon was cut by the screw in either group. There was no significant difference between the forces required to produce specific amounts of graft slippage between the two fixation techniques tested. There was no significant difference between the average total slippage at maximum pullout, 11.8 mm for the screw placed in the eccentric position and 13.7 mm for the screw placed in the central position. The maximum pullout force averaged 265.3 N for the screw placed in the eccentric position, and 244.7 N for the screw placed in the central position; these values were not significantly different. Placement of the interference screw in the central position did not compromise strength and it improves graft contact within the bone tunnel. Interference screw fixation, when applied against a bone plug, has been shown to consistently have a pullout force of more than 400 N.Arthroscopy 1998 Jul-Aug;14(5):459-64     

Evaluation of an interference screw for tendon reattachment to small bones

OBJECTIVES: To compare the strength of interference screw fixation of the tendon to suture button fixation and staple fixation methods. DESIGN: Biomechanical study. METHODS: The femurs and flexor digitorum tendon of twelve rabbits were used. The tendon was attached to the medial condyle of the femur using one of the following three surgical procedures: (a) interference screw fixation: tendon-junction screw was used as an interference screw, (b) suture button fixation: the tendon was inserted through a hole and attached with a button on the opposite side, and (c) staple fixation: the tendon was attached using two staples. Strengths of the attached tendons were then measured using a universal testing machine. RESULTS: The ultimate failure load of interference screw fixation was 62.8 +/- 9.0 N, whereas that of suture button fixation was 13.9 +/- 3.8 N and staple fixation was 23.9 +/- 2.6 N. CONCLUSION: Interference screw fixation provides significant initial fixation strength (p < 0.05).     

No Tunnel 2-Socket Technique: All-Inside Anterior Cruciate Ligament Double-Bundle Retroconstruction

This report describes an all-inside, double-bundle anterior cruciate ligament retroconstruction (all-inside ×2 technique), which is a less invasive technique because of the use of sockets (2 femoral and 2 tibial) instead of complete bone tunnels. When performed with allograft, this may be termed a “no-incision” technique. The femoral sockets are reamed via the anteromedial arthroscopic portal. The tibial sockets are created with the all-inside RetroDrill (Arthrex, Naples, FL) from within the joint. The posterolateral bundle graft is passed first and shuttled through the anteromedial portal and fixed on the femur with a RetroButton (Arthrex), interference screw, or both. It is then fixed on the tibia with a bioabsorbable RetroScrew (Arthrex) near full extension. The anteromedial bundle graft is passed through next, and the process is repeated with tibial fixation performed at 45° of flexion. Posterolateral and anteromedial tibial fixation may be backed up by tying over a cortical button.     

Biomechanical evaluation of open suture anchor fixation versus interference screw for biceps tenodesis

Biceps tenodesis provides reliable pain relief for patients with biceps tendon abnormality. Previous cadaver studies have shown that, for biceps tenodesis, an interference screw provides biomechanical strength to failure superior to that of suture anchors. This finding has led some providers to conclude that screw fixation for biceps tenodesis is superior to suture anchor fixation. The purpose of the current study was to test the hypothesis that the strength of a 2-suture-anchor technique with closing of the transverse ligament is equal to that of interference screw fixation for biceps tenodesis.In 6 paired, fresh-frozen cadaveric shoulder specimens, we excised the soft tissue except for the biceps tendon and the transverse ligament. We used 2 different methods for biceps tenodesis: (1) suture anchor repair with closing of the transverse ligament over the repair, and (2) interference screw fixation of the biceps tendon in the bicipital groove. Each specimen was preloaded with 5 N and then stretched to failure at 5 mm/sec on a materials testing machine. The load-to-failure forces of each method of fixation were recorded and compared. Mean loads to failure for the suture anchor and interference screw repairs were 263.2 N (95% confidence interval [CI], 221.7-304.6) and 159.4 N (95% CI, 118.4-200.5), respectively. Biceps tenodesis using suture anchors and closure of the transverse ligament provided superior load to failure than did interference screw fixation. This study shows that mini-open techniques using 2 anchors is a biomechanically comparable method to interference fixation for biceps tendon tenodesis.     

Initial fixation strength of modified patellar tendon grafts for anatomic fixation in anterior cruciate ligament reconstruction.

Recently it has been shown that anatomic tibial graft fixation in anterior cruciate ligament (ACL) reconstruction is preferable in order to increase isometry and knee stability. To facilitate anatomic patellar tendon graft fixation, customized graft length shortening is necessary. The purpose of this study was to compare the initial fixation strength of four different shortened patellar tendon grafts including three bone plug flip techniques and direct patellar tendon-to-bone interference fit fixation in a model with standardized bone density. Ninety calf tibial plateaus (22 to 24 weeks old) with adjacent patella and extensor ligaments were used. Tendon grafts were shortened by flipping the bone plug over the tendon leaving a tendon-tendon-bone (TTB) construct and, as the first modification in the opposite direction resulting in a tendon-bone-tendon (TBT) construct. The second modification consisted of the TBT construct with interference screw position at the lateral aspect of the bone plug (TBTlat). As the fourth modification the tendon graft was directly fixed (Tdirect) with an interference screw. In addition, a round-threaded titanium (RCI; Smith & Nephew DonJoy, Carlsbad, CA), a round-threaded biodegradable screw (Sysorb; Sulzer Orthopedics, Münsingen, Switzerland), and a conventional titanium interference screw (Arthrex Inc, Naples, FL) were compared. We found that TTB (mean 441 N for biodegradable screw, 357 N for RCI screw, 384 N for conventional screw) and TBT (mean 407 N for biodegradable screw, 204 N for RCI screw, 392 N for conventional screw) construct fixation achieves comparable fixation strength, although failure in the TTB was due to tendon strip off at its ligamentous insertion. The highest failure load was found in TBTlat fixation (mean 610 N for biodegradable screw, 479 N for RCI screw). Therefore, this technique should be recommended when using a tendon flip technique. The failure load for Tdirect fixation (mean 437 N for biodegradable screw, 364 N for RCI screw) was similar to that of TTB and TBT fixation, which may indicate that a patellar-tendon graft harvested without its patellar bone plug and directly fixed with an interference screw is equivalent to a flipped graft. This may additionally reduce harvest site morbidity and eliminates the risk of patellar fracture. The fixation strength of round-threaded biodegradable and conventional titanium interference screws was similar, whereas that of round-threaded titanium screws was significantly lower in the patellar tendon flip-techniques. However, it should be taken into consideration that round-threaded titanium screws are proposed for direct tendon-to-bone fixation.     

Biomechanical evaluation of patellar- and hamstring tendon graft fixation for anterior cruciat ligament reconstruction using a poly-(D, L-lactide) interference screw

Anterior cruciate ligament (ACL) reconstruction using autologous hamstring tendons are being performed more frequently and satisfactory results have been reported. Advantages such as low donor site morbidity and ease of harvest as well as disadvantages like low initial construct stiffness have been described. Recently, it has been demonstrated that graft fixation close to the original ACL insertion sites increases anterior knee stability and graft isometry. Hamstring tendon fixation techniques using interference screws offer this possibility. To reduce the risk of graft laceration, a round threaded titanium interference screw (RCI) was developed. To improve initial fixation strength, fixation techniques for hamstring tendons with separate or attached tibial bone plugs were introduced. However, data on fixation strength do not yet exist. With respect to the proposed advantages of biodegradable implants, like undistorted magnetic resonance imaging, uncompromised revision surgery and a decreased potential of graft laceration during screw insertion, we performed pullout tests of round threaded biodegradable and round threaded titanium interference screw fixation of semitendinosus (ST) grafts with and without distally attached tibial bone plugs. Data were compared with bone-tendon-bone (BTB) graft fixation using biodegradable and conventional titanium interference screws. We used 56 proximal calf tibiae to compare maximum pullout force, screw insertion torque, and stiffness of fixation for biodegradable direct ST tendon and bone plug fixation (group I: without bone plug, group II: with bone plug) versus titanium interference screw fixation (group III: without bone plug, group IV: with bone plug). A round threaded biodegradable poly-(D, L-lactide) (Sysorb) and a round threaded titanium interference screw (RCI) were used. As a control calf bone-tendon-bone (BTB) grafts fixed with either poly-(D, L-lactide) (group V) or conventional titanium (group VI) interference screws were used. ST tendons were harvested either with or without their distally attached tibial bone plugs from human cadavers and were folded to a three-stranded graft. Specimen were loaded in a material testing machine with the applied load parallel to the long axis of the bone tunnel. Maximum pullout force of ST bone plug (group III: 717 N +/- 90, group IV: 602 N +/- 117) fixation was significantly higher than that of direct tendon (group I: 507 N +/- 93, group III: 419 N +/- 77) fixation. Maximum pullout force of biodegradable screw ST fixation was higher than that of titanium screw fixation in both settings. There was no significant difference in pullout force between biodegradable (713 N +/- 210) and titanium (822 N +/- 130) BTB graft fixation or between ST fixation with bone plug and biodegradable screw with BTB fixation. Pullout force of hamstring tendon interference screw fixation can be improved by using a biodegradable implant. In addition, initial pullout force can be greatly improved by harvesting the hamstring tendon graft with its distally attached tibial bone plug. This may be important, especially in improving tibial graft fixation. This study encourages further research in tendon-bone healing with direct interference screw fixation to confirm the potential of this advanced method.     

Biomechanical assessment of an alternative method of staple fixation for anchoring the Bone Patellar Tendon Bone graft to the tibia

Introduction

The Anterior cruciate ligament (ACL) is the most commonly injured ligament around the knee and is best reconstructed with a biological graft. For ideal graft fixation, there should be sufficient initial strength to avoid failure of fixation and sufficient stiffness to restore the stability of the knee and to avoid gradual loosening in the post-operative period.When considering fixation of Bone Patellar Tendon Bone (BPTB) grafts to the tibia, the interference screw is considered to be the gold standard. As an alternative, we have used of staples and stainless steel (SS) wire to anchor the BPTB graft to the tibia and femur. The aim of this study was to assess the biomechanical efficacy of this fixation technique for anchoring the BPTB graft to the proximal tibia. We used a bovine model to compare three fixation techniques ?interference screw, braided polyester sutures tied to a screw post and SS wire tied to a staple.

Distal attachment of flexor tendon allograft: A biomechanical study of different reconstruction techniques in human cadaver hands

We compared the mechanical force of tendon‐to‐bone repair techniques for flexor tendon reconstruction. Thirty‐six flexor digitorum profundus (FDP) tendons were divided into three groups based upon the repair technique: (1) suture/button repair using FDP tendon (Pullout button group), (2) suture bony anchor using FDP tendon (Suture anchor group), and (3) suture/button repair using FDP tendon with its bony attachment preserved (Bony attachment group). The repair failure force and stiffness were measured. The mean load to failure and stiffness in the bony attachment group were significantly higher than that in the pullout button and suture anchor groups. No significant difference was found in failure force and stiffness between the pullout button and suture anchor groups. An intrasynovial flexor tendon graft with its bony attachment has significantly improved tensile properties at the distal repair site when compared with a typical tendon‐to‐bone attachment with a button or suture anchor. The improvement in the tensile properties at the repair site may facilitate postoperative rehabilitation and reduce the risk of graft rupture. © 2013 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 31:1720–1724, 2013     

The effect of mitek anchor insertion angle to attachment of FDP avulsion injuries

Flexor digitorum profundus (FDP) tendon avulsions, although uncommon, are not infrequent injuries. A widely accepted method of treating Type 1 FDP avulsions is a pullout suture tied over a button on the nail plate. The external dorsal button is often a source of inconvenience for the patient. Potential risks associated with button use include nail plate deformities, nail fold necrosis and infections tracking along the sutures. The use of small suture anchors provides a satisfactory alternative, because buried fixation avoids these potential complications. This in vitro, biomechanical study examined the influence of the anchor orientation on the properties of the repaired FDP tendon using human cadavers.     

The low-profile Roman bridge technique for knotless double-row repair of the rotator cuff

With advances in arthroscopic surgery, many techniques have been developed to increase the tendon–bone contact area, reconstituting a more anatomic configuration of the rotator cuff footprint and providing a better environment for tendon healing. We present a low-profile arthroscopic rotator cuff repair technique which uses suture bridges to optimize rotator cuff tendon–footprint contact area and mean pressure. A 5.5 mm Bio-Corkscrew suture anchor (Arthrex, Naples, FL, USA), double-loaded with No. 2 FiberWire sutures (Arthrex, Naples, FL, USA), is placed in the anteromedial aspect of the footprint. Two suture limbs from a single suture are both passed through a single anterior point in the rotator cuff. One suture limb is retrieved from the cannula. The second suture limb is passed through a single posterior point in the rotator cuff producing two points of fixation in the tendon, with a tendon bridge between them. The same suture limb is retrieved through the lateral portal, and then inserted into the bone by means of a Pushlock (Arthrex, Naples, FL, USA), placed approximately 1.5–2 cm posterior to the first anchor. This second suture is passed again in the posterior aspect of the cuff. The limbs of the first suture are pulled to compress the tendon in the medial aspect of the footprint. The two free suture limbs are used to produce suture bridges over the tendon by means of a Pushlock (Arthrex, Naples, FL, USA), placed 1 cm distal to the lateral edge of the footprint relative to the medially placed suture anchors anterior to posterior. This technique allows us to perform a low-profile (single pulley–suture bridges) repair for knotless double-row repair of the rotator cuff.     

Posterolateral Corner Reconstruction of the Knee: Surgical Technique Utilizing a Bifid Achilles Tendon Allograft and a Double Femoral Tunnel

Reconstruction of the posterolateral corner of the knee has received increased attention in the recent literature. Basic science studies have helped us determine the 3 critical structures of the posterolateral corner: the lateral collateral ligament (LCL), the popliteus tendon, and the popliteofibular ligament. We have developed an anatomic posterolateral corner reconstruction that most closely resembles these 3 key structures and is based on the work of previous authors. Our technique is performed using a single Achilles allograft. The bone plug is secured in a femoral tunnel at the anatomic attachment of the popliteus tendon with an interference screw. The Achilles tendon is then split approximately 1 to 2 cm distal to the bone plug into 2 segments: (1) the popliteofibular ligament portion that is passed through a fibular tunnel starting at the anatomic attachment of popliteofibular ligament and fixed with a biointerference screw and (2) the static portion of the popliteus tendon securing this through a tibial tunnel passed from posterior to anterior right at the musculotendinous junction of the popliteus. The anterior limb of the Achilles tendon exiting the fibula is then brought back around, secured to the fibular attachment of the LCL with a suture anchor, and is then passed through a separate femoral tunnel placed at the anatomic attachment of the LCL.     

Biomechanical properties of interference screw implantation in replacement of the anterior cruciate ligament with patellar and hamstring transplants. An experimental study using roentgen stereometry analysis (RSA)

This experimental roentgen stereometric analysis (RSA) study was performed to measure micromotions between the graft and tunnel under submaximal load in anterior cruciate ligament (ACL) reconstruction. The aim was to evaluate the maximum load at failure, linear stiffness, and slippage of bone-patellar-tendon-bone (BPTB) grafts fixed with interference screws compared to quadrupled hamstring grafts fixed with interference screws. We used 15 porcine tibia specimens for the study. In the BPTB group, the 10 x 25-mm bone plugs were fixed in a tunnel with 10 mm in diameter using a 7 x 25-mm titanium interference screw (n = 5) or a biodegradable screw (n = 5). The five hamstring transplants were folded to a four-stranded graft and armed with a baseball stitch suture. The sutured side was fixed with a 7 x 25-mm biodegradable polylactide screw in an 8-mm tunnel. The tibial bones, tendon grafts, and interference screws were marked with tantalum beads. The grafts were mounted to a custom made load frame and loaded parallel to the axis under RSA control increasing the force in steps of 50 N. Micromotions between bone plug, screw, and tibia were measured with RSA. Accuracy of RSA for the in vitro study was evaluated as 0.05 mm. Hamstring grafts failed at significantly lower maximum loads (492 +/- 30 N) than BPTB grafts (658 +/- 98 N). Linear stiffness of the hamstring graft fixations was eight times lower compared to the BPTB grafts (403 +/- 141 N/mm vs 3500 +/- 1300 N/mm). There was no significant difference between the biodegradable and titanium screws in the BPTB group. Slippage of the graft started at 82 +/- 35 N load in the hamstring group and at 428 +/- 135 N in the BPTB group. Slippage of the graft at 75% of the maximum pull-out strength was measured as 0.36 +/- 0.25 mm in the BPTB and 2.58 +/- 1.08 mm in the hamstring group. The interference screw fixation of a quadrupled hamstring graft showed a lower linear stiffness and an earlier slippage compared to a patellar tendon bone plug. Slippage of the hamstring grafts at submaximal loads may result in fixation failure during rehabilitation.     

Histological findings of tendon-bone healing following anterior cruciate ligament reconstruction with hamstring grafts

BACKGROUND: The purpose of the study was the histological examination of tendon-bone healing of hamstring grafts after anterior cruciate ligament (ACL) reconstruction. METHODS: During five arthroscopies done 6-14 months after ACL reconstructions, biopsies of the wall of the former drilled femoral canal were obtained. Four patients were primarily operated on using a suspending device (Endobutton, Acufex Microsurgical, Mansfield, MA, USA, and Transfix, Arthrex, Naples, FL, USA) for femoral fixation, one patient was reconstructed with a biodegradable interference screw directly inserted between the tendon and the wall of the canal. Biopsies were obtained using a tube harvester during re-arthroscopy. Three grafts were stable, two grafts were unstable, and revision of the ACL was performed. RESULTS: Histologically, in the four cases of reconstruction with a button or a rectangular pin, biopsies resembled granulation tissue without insertion of fibers between the tendon tissue and the bony wall. A wide area of woven bone was noted adjacent to the pre-existing lamellar bone. In contrast, the tendon-bone junction in the knee reconstructed with a biodegradable interference screw resembled a zone of metaplastic fibrous cartilage between the tendon graft and the lamellar bone. Collagen fibers connecting the tendon-bone interface occurred under polarized light microscopy. CONCLUSION: We conclude that the use of hamstring grafts for ACL reconstruction can lead to different histological pattern of tendon-bone healing. Micromotion of the hamstring graft inside the drilled canal can be play a role in tendon-bone healing.     

Mechanical strength of arthroscopic rotator cuff repair techniques: an in vitro study

BACKGROUND: Retears after rotator cuff repairs occur relatively frequently and may compromise the functional result. The goal of this study was to analyze the mechanical properties following arthroscopic techniques for rotator cuff repair and to evaluate possible alternative techniques. METHODS: In the first part, five different bone anchors (the Revo screw; Mitek Rotator Cuff anchor, 5.0-mm Statak, PANALOK RC absorbable anchor, and 5.0-mm Bio-Statak) were tested in vitro under cyclic loading on five pairs of cadaveric shoulders. Then five types of arthroscopic tendon suturing instruments were tested on rotator cuff tendons. Finally, the arthroscopically performed mattress and modified Mason-Allen stitches, fixed with either the Revo screw or the Bio-Statak, were evaluated on ten pairs of human cadaveric shoulders. RESULTS: The holding strengths of the various anchors were similar, ranging from 130 to 180 N, and approximated the holding strength of knotted number-2 suture materials. The fixation of the tested anchors yielded comparable values of stiffness except for one anchor, which showed significantly greater subsidence under cyclic load (p = 0.003). All tested, commercially available arthroscopic suturing devices were unsuitable for performing a modified Mason-Allen stitch on normal supraspinatus tendons. Modification of a commercially available suture punch with a longer needle allowed us to consistently perform a modified Mason-Allen stitch. The modified Mason-Allen stitch, which has shown favorable mechanical properties in open repairs of the rotator cuff, was not found to be stronger than the mattress stitch when performed arthroscopically and used with bone anchors. When the modified Mason-Allen stitch was fixed to one anchor, it was even weaker than a mattress stitch repaired with another anchor (168 versus 228 N). Unequal loading of the two suture branches due to the more rigid modified Mason-Allen stitch may be the reason for this difference. CONCLUSIONS: Arthroscopic techniques for rotator cuff repair with use of the mattress stitch and bone anchors allow for a relatively solid fixation. The holding strength is not improved with use of the modified Mason-Allen stitch. Although a direct comparison with previous in vitro studies is not possible, the holding strength of open fixation techniques seems to be stronger. If rotator cuffs are subjected to high postoperative loading, open repair might be preferred to reduce the risk of a retear, until stronger arthroscopic fixation techniques are developed.     

Acromioclavicular reconstructions with hamstring tendon grafts: a comparative biomechanical study

The surgical treatment of chronic acromioclavicular injuries remains controversial. There is increasing use of autogenous tendon grafts to perform these reconstructions. This study examined the mechanical properties of differing configurations of these grafts. Mechanical testing of acromioclavicular joint reconstructions was performed with a screw and soft tissue washer for tendon fixation, a simple loop of tendon tied to itself, and a bio-interference screw for tendon fixation, with and without a loop of nonabsorbable suture for reinforcement. The bio-interference screw fixation, with reinforcement by a loop of nonabsorbable suture, gave the highest load to failure among the group (502N +/- 177), which was not significantly different from the intact ligaments (705 N +/- 132), although it was significantly less stiff than the intact group (57.2 N/mm +/- 12.6 and 109.7 N/mm +/- 32.6, respectively). All other reconstructions had an ultimate load and stiffness which were significantly less than that of the intact specimens.     

Impact of tendon suturing on the interference fixation strength of quadrupled hamstring tendon grafts

Introduction

Interference screw fixation of soft tissue grafts has been a widely used fixation technique for cruciate ligament reconstruction. Suturing of the graft construct prior to graft fixation has been proposed to increase fixation strength; however, the effect on mechanical properties has not been well characterized. The goal of this study was to determine whether uniform suturing of the tendon graft affects (1) ultimate fixation strength of the hamstring tendon graft and (2) motion of the tendon in the bone tunnel during cyclic loading when comparing sutured grafts vs. unsutured grafts.

Method

Eight pairs of matched mature porcine tibias (age <2 years) and eight paired fresh-frozen human quadrupled hamstring tendon grafts were used. One quadrupled graft from each pair was placed into one of two groups. In the group A a single cerclage suture 3 cm from the doubled end of the graft was placed to join the four tendon strands. In group B a heavy suture was used to tightly unite the four strands of tendon graft to provide a better grip for the interference screw during fixation. The grafts were placed in tibial bone tunnels that matched the graft’s diameter and fixed with an interference screw. The looped end of the graft and the attached tibia were rigidly fixed in a material testing machine. The graft constructs were subjected to 100 cycles of 20–250 N load, followed by a load-to-failure test. In addition, a motion analysis system was used during cyclic testing to better determine the amount of elongation at the graft–tunnel interface. Statistical analysis of the failure load and stiffness and the overall elongation following cyclical loading was performed using the Wilcoxon rank sum test. Level of significance was set at p < 0.05.

Results

Elongation at the tendon–bone interface during sub-maximal cyclic loading was 2.4 ± 1.4 mm (unsutured) vs. 2.0 ± 0.7 mm (sutured) (p > 0.05). Failure load of the grafts without sutures (634 ± 86 N) was significantly lower than with the sutures (837 ± 183 N). Ultimate stiffness of group A (283 ± 34 N/mm) was lower than that of group B (331 ± 51 N/mm); however, this was not statistically significant (p = 0.051).

Conclusion

This study confirms that suturing of the graft construct before interference screw fixation may increase ultimate failure load. However, an improvement of structural properties in response to cyclic loading with sub-maximal loads could not be confirmed. Clinicians using interference screw fixation may suture the graft to improve fixation strength; however, suturing does not appear to allow a more aggressive rehabilitation after surgery.     

FASTIN骨锚在肌腱、韧带止点重建中的应用

目的探讨FASTIN骨锚在肌腱、韧带止点重建中的应用。方法选取2006年3月至2010年3月期间46例不同部位肌腱、韧带止点处撕脱性骨折或断裂患者(男性28例,女性18例)。采用合适的FASTIN骨锚,包括微型骨锚和螺纹骨锚,对患者予以肌腱、韧带止点重建,术后随访X线和关节功能。结果 46例患者中,根据不同部位肌腱、韧带止点撕脱性骨折或断裂的特点,16例采用微型骨锚,30例采用螺纹骨锚。术后随访6~13个月,平均9个月。采用FASTIN骨锚重建止点,操作简单,平均手术时间1.5 h,明显短于传统固定手术,术后重建区关节功能满意,无压痛,日常生活、工作无影响。X线未见锚钉松动、脱落。结论 FASTIN骨锚在肌腱、韧带止点重建中具有独特的优势,值得进一步推广和应用。