Behavior of sutures used in anterior cruciate ligament reconstructive surgery

Tissue Augmentation Techniques in the Management of Ligamentous Knee Injuries

Despite early reports of high failure rates in knee ligament repair techniques resulting in favor of reconstruction, newer advances in surgical technology have shifted the attention back to repair with the addition of various tissue augmentation techniques. Ligament repair preserves proprioceptors in the native ligament and avoids autograft tendon harvest, minimizing the complications associated with donor site ruptures in reconstruction techniques. Tissue augmentation has been successfully used in knee ligamentous and tendon repair procedures, as well as in some upper extremity procedures. This study provides a clinical update on the surgical techniques, biomechanics, and outcomes with the application of various tissue augmentation techniques in the ligaments surrounding the knee joint.

Efficacy of repair for ACL injury: a meta‑analysis of randomized controlled trials

We aim to compare the curative effect of primary repair for anterior cruciate ligament (ACL) injury with reconstruction and provide the reliable evidence for its clinical application. The literatures were searched in PubMed, EMBASE, Springer, and other medical literature databases published between January 1970 and June 2021. Basic characteristics, surgery technique, clinical outcome scores and physical examination results were recorded and evaluated. Seven randomized controlled trials (RCT) were eligible for inclusion. The results showed that there were no statistically significant differences between arthroscopic ACL repair and ACL reconstruction for Tegner, Lysholm, Lachman, KT-1000, range of motion (ROM), functional outcomes and reoperation rate (P > 0.05), even the result of IKDC scores showed that arthroscopic repair was better than reconstruction (P = 0.04). However, through the subgroup analysis, it was found that the short-term follow-up results of arthroscopic ACL repair were indeed better than those of open ACL repair. Therefore, we can assume that the arthroscopic ACL repair technique is an optional and promising surgical method to treat ACL injury.

Anterior Cruciate Ligament Repair with Suture Augmentation for Proximal Avulsion Injuries

Purpose

To assess failure rate, outcomes, and patient satisfaction in patients who underwent anterior cruciate ligament (ACL) repair with suture augmentation for clinical instability and proximal avulsion of the ACL.

Methods

We retrospectively reviewed consecutive suture-augmented ACL repairs performed by a single surgeon between January 2014 and June 2016 for proximal ACL avulsion. Patients were included if they were at least 24 months postoperative from repair surgery. Patients were excluded from the study if they underwent primary ACL reconstruction instead of repair or if they had a concomitant multiligamentous knee injury. Knee Injury and Osteoarthritis Outcome Score (KOOS), visual analog scale (VAS), Veterans RAND-12 (VR-12), Marx Activity, and Single Assessment Numeric Evaluation data were collected.

Results

Of 172 patients who underwent ACL surgery between January 2014 and June 2016, 28 (16%) with Sherman type I or II ACL tears or high-grade partial avulsion with clinical instability underwent ACL repair with suture augmentation. One patient was not available for follow-up. The 27 patients were age 27.4 ± 8.6 years, 18 males (66.7%), and 2.8 ± 0.7 years follow-up (range, 2.0-3.8 years). Of these 27 patients, 4 recurrent ACL injuries (14.8%) required revision to reconstruction. The remaining 23 patients had successful ACL repair with no clinical instability and no subjective complaints at final follow-up. Final scores were KOOS 83.7 ± 12.8, Marx 8.6 ± 4.0, VAS 1.1 ± 1.8, physical VR-12 53.6 ± 5.2, mental VR-12 53.1 ± 8.1, and Single Assessment Numeric Evaluation 83.0 ± 12.9. In the 11 patients with baseline data, significant improvements were observed in composite KOOS (50.4 ± 11.5 to 85.7 ± 8.4; P < .001; VAS: 3.9 ± 2.6 to 0.8 ± 0.8; P = .002; and physical VR-12: 39.9 ± 6.5 to 55.5 ± 3.3; P < .001). All 11 patients (100%) met or exceeded the KOOS composite minimum clinically important difference (mean 34.0 increase).

Conclusions

In patients with proximal ACL avulsion, arthroscopic primary ACL repair with suture augmentation demonstrated high functional outcome and improved patient-reported outcomes at 2-year follow-up. The rate of graft failure was 15%.

Level of Evidence

Level IV, therapeutic case series.

Interference Screw Versus Suture Endobutton Fixation of a Fiber-Reinforced Meniscus Replacement Device in a Human Cadaveric Knee Model

BACKGROUND

Meniscal lesions represent one of the most common intra-articular knee injuries. Meniscus replacement devices are needed to restore load distribution and knee stability after meniscectomy. Fixation of these devices is crucial to the generation of hoop stresses and the distribution of loads in the joint.

PURPOSE

To evaluate 2 different fixation techniques (suture endobutton and interference screw) for implantation of a novel meniscus device.

STUDY DESIGN

Controlled laboratory study.

METHODS

In 7 human cadaveric knees (aged 17-61 years), 1 anterior and 2 potential posterior tunnel locations were investigated, and both fixation techniques were tested in each tunnel. The native meniscus roots, devices fixed with a suture endobutton, and devices fixed with an interference screw were gripped with cryoclamps, and tibias were drilled and loaded into a custom jig. Samples were preloaded, preconditioned, loaded for 500 cycles (50-150 N), and tested in tension until failure.

RESULTS

For all 3 tunnels, suture fixation resulted in greater elongation (54.1%-150.7% greater; P < .05) during cyclic loading than interference screw fixation, which approximated the native roots. Both fixation techniques displayed ultimate tensile loads in the same range as native roots. However, stiffness of the suture fixation groups (36.5-41.6 N/mm) was only 28% to 37% of that of the interference screw fixation groups (98.7-131.6 N/mm), which had values approaching those of the native roots (anterior: 175.4 ± 24.2 N/mm; posterior: 157.6 ± 22.9 N/mm).

CONCLUSION

Interference screw fixation was found to be superior to suture fixation with regard to elongation and stiffness, a finding that should be considered in the design and implantation of novel meniscus replacement devices.

CLINICAL RELEVANCE

With the emergence of various devices for total meniscus replacement, the establishment of fixation strategies is crucial for the generation of tensile hoop stresses and the efficacy of these approaches.

Ultra-flexible Piezoelectric Devices Integrated with Heart to Harvest the Biomechanical Energy

Power supply for medical implantable devices (i.e. pacemaker) always challenges not only the surgery but also the battery technology. Here, we report a strategy for energy harvesting from the heart motion by using ultra-flexible piezoelectric device based on lead zirconate titanate (PZT) ceramics that has most excellent piezoelectricity in commercial materials, without any burden or damage to hearts. Experimental swine are selected for in vivo test with different settings, i.e. opened chest, close chest and awake from anesthesia, to simulate the scenario of application in body due to their hearts similar to human. The results show the peak-to-peak voltage can reach as high as 3 V when the ultra-flexible piezoelectric device is fixed from left ventricular apex to right ventricle. This demonstrates the possibility and feasibility of fully using the biomechanical energy from heart motion in human body for sustainably driving implantable devices.

Immediate ACL reconstruction prevents microvascular pathophysiology in the uninjured MCL that is not fully reversed by delayed ACL reconstruction

Anterior cruciate ligament (ACL) injury induces maladaptive vascular responses that degrade medial collateral ligament (MCL) function. The purpose of this study was to determine if early or delayed ACL reconstruction can prevent or reverse the abnormal changes in vascular function that occur in the uninjured MCL after ACL injury. Twenty-four rabbits were divided into four groups (n = 6); control, ACL-deficient (ACL-X), immediate ACL reconstructed (ACL-IR) and delayed ACL reconstructed (ACL-DR). After 8 weeks, MCLs were assessed for blood flow, responses to acetylcholine (ACh) and phenylephrine (Phe) and autoregulatory responses, using laser speckle perfusion imaging. In ACL-X knees, blood flow in the MCL increased by 2.5-fold compared to control. MCL hyperemia was diminished in ACL-DR knees and was unaltered in ACL-IR knees. MCL vasculature was unresponsive to ACh and Phe in ACL-X. These responses were partially restored by ACL reconstruction. Autoregulatory responses were not significantly different between groups. ACL-DR decreased hyperemia in the MCL and partially attenuated abnormal MCL vascular responses. ACL-IR was more effective at preventing MCL hyperemia and preserving vascular responsiveness to ACh and Phe. This suggests that the vascular alterations in the uninjured rabbit MCL are largely caused by abnormal mechanical loading resulting from ACL deficiency and can be prevented through early reconstruction. Early ACL reconstruction could limit the progression of microvascular dysfunction of the MCL, and preserve physiological joint homeostasis. This might prevent joint degeneration and delay the progression of osteoarthritis.

Artroplastia glenoumeral: resistência do fio de poliéster após contato com o metilmetacrilato

OBJETIVO: Os autores estudam as características do fio de poliéster (ethibond) após o contato com o metilmetacrilato (cimento ortopédico) no laboratório de resistência de materiais. MÉTODOS: Avaliam a força necessária para a ruptura bem como a elasticidade e a deformidade provocadas durante a tração no aparelho Instron 4482. Realizam análise estatística através do teste "t-student". RESULTADOS: Não encontram diferença estatisticamente significativa entre os grupos estudados. CONCLUSÃO: Concluem que o contato do metilmetacrilato com o poliéster não acarreta mudanças na suas propriedades elásticas e de resistência à tração.

Biomechanical comparison of modified Kessler and running suture repair in 3 different animal tendons and in human flexor tendons

PURPOSE

To establish the animal flexor tendon that best mimics the biomechanical performance of human flexor tendons. We investigated the biomechanical behavior of core and running sutures in 3 different animal flexor tendons and in human flexor tendons. Additionally, we attempted to help standardize future flexor tendon studies. To that purpose, nearly all variables occurring in the test setup have been highlighted.

METHODS

The species selected were pig, calf, sheep, and human. Two groups were formed. In the first group we tested 3-0 core sutures (Ticron; Tyco Healthcare, Vienna, Austria), and in the second group we tested 5-0 running sutures (Ethilon; Ethicon, Vienna, Austria). In each group, 10 tendons of each specimen were tested, which yielded a total of 80 tendons. In each group, the repaired tendons were subjected to 3,000 linear load cycles at a load of 15 N. At the end of this procedure, final gap values were recorded. In the next step, ultimate load-to-failure data were obtained from each specimen.

RESULTS

Core sutures behaved similarly in the human, sheep, and pig tendons with respect to ultimate loads. With respect to gap formation, core sutures behaved similarly in the human, sheep, and calf tendons. Deep running sutures behaved similarly in the human, sheep, and pig tendons in terms of ultimate load to failure.

CONCLUSIONS

In this study, sheep tendons were found to best mimic the biomechanical behavior of human tendons. Calf tendons seem to be unsuitable. There is a strong need for consistency in biomechanical test setups.

Arthroscopic anterior cruciate ligament reconstruction with the tibial-remnant preserving technique using a hamstring graft

We propose that the tibial remnant of the anterior cruciate ligament (ACL) is able to enhance the revascularization and cellular proliferation of the graft, to preserve proprioceptive function, and to be able to acquire anatomic placement of the graft without roof impingement. Therefore, it seems reasonable to assume that preserving the tibial remnant as much as possible as a source of reinnervation, if technically possible without causing impingement, would be of potential benefit to the patient. Our surgical technique was developed to maximize the preservation of the tibial remnant. The distally attached semitendinosus and gracilis tendons are harvested using the tendon stripper. After satisfactory placement of 2 guide pins convergently, a closed-end socket in the lateral femoral condyle is created using an adequately sized curved curette. For anatomic placement of the graft, the tibial tunnel should be positioned within the boundaries of the normal ACL tibial remnant. The reamer must be advanced very carefully to minimize injury to the residual remnant at the intra-articular margin of the tibial tunnel. Penetration should stop at the base of the stump. The folded grafts are then pulled intra-articularly through the tibial tunnel, the tibial remnant, and the femoral socket by pulling sutures under arthroscopic visualization. The ACL tibial remnant is compacted by the tendon passage. The graft is secured proximally by tying sutures in the lateral femoral condyle and distally at the tibia with double staples by a belt-buckle method. The advantages of our technique include maximal preservation of the tibial remnant, no roof impingement caused by intrasynovial anatomic placement of the graft, the simplicity of the procedure, the minimal need for hardware or special instruments, the economic benefit, and the potential prevention of tibial tunnel enlargement by preventing synovial fluid leakage.

Equal tension in all four strands of a semitendinosus graft with a low profile tibial fixation device (Cobra LFD)

The article introduces a novel tibia fixation device, the Cobra Ligament Fixation Device (Cobra LFD), for anterior cruciate ligament reconstruction. The Cobra LFD has a low profile and is hooked upon the cortical bone of tibia. It is useful either for primary ACL reconstruction or for ACL revision surgery, mainly for fixation of hamstring grafts. Fixation in the cortical bone is of great importance, in particular for revision cases. Besides technical aspects, we also present the 4-year follow-up of 15 cases of ACL revision surgery, where the Cobra LFD has been used for the tibia fixation.

Primary stability of three posterior cruciate ligament reconstruction procedures: a biomechanical in vitro study

PURPOSE

Posterior cruciate ligament (PCL) reconstruction procedures have not been thoroughly evaluated under cyclic loading conditions. We tested the hypothesis that PCL reconstruction with a quadrupled flexor-tendon graft and fixation using tapes and staples is biomechanically superior to that fixed with sutures, a button, and a post-screw, and is comparable to reconstruction with a bone--patellar tendon--bone (BPTB) graft.

STUDY DESIGN

In vitro biomechanical study.

METHODS

A total of 45 porcine knees were used. The quadrupled flexor-tendon graft was fixed using the suture/button/post-screw procedure in 15 knees, and with the tape/staples procedure in another 15 knees. The remaining 15 knees underwent reconstruction with a BPTB graft secured with screws as the standard control. In each group of 15 knees, 5 underwent tensile testing without cyclic loading, and 10 underwent the same tensile test after 5,000 cycles of load-controlled or displacement-controlled loading.

RESULTS

Each type of cyclic loading produced larger biomechanical changes in the knees fixed with the suture/button/post-screw procedure than in the knees secured using the other 2 procedures.

CONCLUSIONS

In PCL reconstruction, the tape/staples procedure is biomechanically superior to the suture/button/post-screw procedure, and is comparable to the BPTB/screws procedure with regard to the ultimate failure load. Neither of the procedures using the quadrupled flexor-tendon graft was comparable to the BPTB graft in linear stiffness and the initial displacement after load-controlled cyclic testing.

CLINICAL RELEVANCE

The biomechanical behaviors of PCL-reconstructed knees are significantly different, depending on surgical techniques.

Biomechanical properties of patellar and hamstring graft tibial fixation techniques in anterior cruciate ligament reconstruction: experimental study with roentgen stereometric analysis

BACKGROUND

Reliable fixation of the soft hamstring grafts in ACL reconstruction has been reported as problematic.

HYPOTHESIS

The biomechanical properties of patellar tendon (PT) grafts fixed with biodegradable screws (PTBS) are superior compared to quadrupled hamstring grafts fixed with BioScrew (HBS) or Suture-Disc fixation (HSD).

STUDY DESIGN

Controlled laboratory study with roentgen stereometric analysis (RSA).

METHODS

Ten porcine specimens were prepared for each group. In the PT group, the bone plugs were fixed with a 7 x 25 mm BioScrew. In the hamstring group, four-stranded tendon grafts were anchored within a tibial tunnel of 8 mm diameter either with a 7 x 25 mm BioScrew or eight polyester sutures knotted over a Suture-Disc. The grafts were loaded stepwise, and micromotion of the graft inside the tibial tunnel was measured with RSA.

RESULTS

Hamstring grafts failed at lower loads (HBS: 536 N, HSD 445 N) than the PTBS grafts (658 N). Stiffness in the PTBS group was much greater compared to the hamstring groups (3500 N/mm versus HBS = 517 N/mm and HSD = 111 N/mm). Irreversible graft motion after graft loading with 200 N was measured at 0.03 mm (PTBS), 0.38mm (HBS), and 1.85mm (HSD). Elasticity for the HSD fixation was measured at 0.67 mm at 100 N and 1.32 mm at 200 N load.

CONCLUSION

Hamstring graft fixation with BioScrew and Suture-Disc displayed less stiffness and early graft motion compared to PTBS fixation. Screw fixation of tendon grafts is superior to Suture-Disc fixation with linkage material since it offers greater stiffness and less graft motion inside the tibial tunnel.

CLINICAL RELEVANCE

Our results revealed graft motion for hamstring fixation with screw or linkage material at loads that occur during rehabilitation. This, in turn, may lead to graft laxity.

Fixation of trochanteric slide osteotomies: a biomechanical study

OBJECTIVE

(1) Determine the effect of a compressive force on the stability of trochanteric slide osteotomies repaired with a cable repair system or a suturing technique. (2) Develop an approach to surgical decision making for trochanteric repair.

DESIGN

Muscle forces acting on the greater trochanter were experimentally modeled by the application of shear and compressive loads to osteotomized greater trochanters. A repeated measures design was used to compare suture and cable fixation.

BACKGROUND

The use of cables and wires for trochanteric repair has been associated with a high incidence of acetabular loosening and trochanteric bursitis. With trochanteric slide osteotomies, the vastus lateralis remains attached to the trochanter, which results in a compressive force being generated across the osteotomy and relatively small shear forces. The use of less rigid fixation techniques for trochanteric repair, such as sutures, may reduce the complications of cables and wires.

METHODS

Seven cadaveric femora with trochanteric osteotomies were tested sequentially after repair with a cable system and with a suturing technique. A cyclic shear load of constant amplitude was applied while a compressive load was decreased in a stepwise fashion. Migration and cyclic motion of the trochanter were measured, and the coefficient of friction was also determined.

RESULTS

Cyclic motions of the trochanter in both superior and anterior directions were generally less than 0.5 mm and were not significantly different between the cables and sutures at high compressive loads. At low compressive loads, cyclic motion was significantly lower with the cable system.

CONCLUSIONS

Compression across the trochanteric slide osteotomy has a significant effect on stability. Cyclic motion of the trochanter is similar for both suture or cable repair of a trochanteric slide with good preservation of soft tissue attachments.

RELEVANCE

Based on theoretical and experimental evidence, repair of trochanteric slide osteotomies with a suture technique may be a viable alternative to the use of cables and wires in selected cases.

Biomechanical comparisons of three posterior cruciate ligament reconstruction procedures with load-controlled and displacement-controlled cyclic tests

BACKGROUND

Biomechanical behaviors of posterior cruciate ligament reconstructions under cyclic loading have not been sufficiently clarified.

HYPOTHESIS

Biomechanical behaviors of the reconstruction that involves use of flexor tendons and an Endobutton are significantly different under cyclic loading from behaviors of the two standard reconstructions in which bone-patellar tendon-bone graft is used.

STUDY DESIGN

Controlled laboratory study.

METHODS

In a porcine model, the tendon/Endobutton reconstruction, the tendon-bone/interference screw reconstruction, and the tendon-bone/tibial-inlay reconstruction were biomechanically compared by using two cyclic tests. In each group of 15 specimens, 5 knees underwent tensile testing without cyclic loading, and the remaining 10 underwent the same tensile test after 5000 cycles of load-controlled or displacement-controlled loading.

RESULTS

At the 5000th cycle, the peak displacement or the peak load was affected by each type of cyclic loading to a significantly greater degree in the knees with the tendon/Endobutton procedure than in the knees reconstructed with the other two procedures.

CONCLUSIONS

Plastic deformation occurred more easily during cyclic loading in the knees with the tendon/Endobutton reconstruction than in the knees with the tendon-bone reconstructions.

CLINICAL RELEVANCE

When the tendon/Endobutton reconstruction is used, a longer period of postoperative immobilization is necessary.

Comparison of the mechanical properties of different tension band materials and suture techniques

OBJECTIVES

This study determined the tensile properties of 18-gauge stainless steel wire, 5-mm woven polyester (Mersilene) tape, and multiple loop configurations of No. 5 braided polyester suture (Ethibond).

DESIGN

Mechanical property testing.

INTERVENTION

Single loops of stainless steel wire, Mersilene, and Ethibond were tested to determine their mechanical properties. Ethibond was tested with different numbers of loops and different knot configurations.

MAIN OUTCOME MEASURES

Stiffness, load at failure, and elongation at failure.

RESULTS

One loop of Mersilene and two loops of Ethibond had similar loads at failure, but the load at failure was significantly higher for stainless steel wire. Four loops of Ethibond withstood a similar failure load to stainless steel wire, but the failure load of the Ethibond suture was greater than the yield load of stainless steel wire. Stainless steel wire had a higher stiffness than both Ethibond and Mersilene. No difference was found in the failure load between different Ethibond knot configurations. The individually tied suture configuration resulted in a higher stiffness than the single-knot configuration. The elongation at failure was not statistically different among the different knot configurations and materials, with the exception of Mersilene tape. Mersilene tape demonstrated a significant increase in elongation at failure as compared to the other materials and knot configurations.

CONCLUSION

It appears that multiple loops of Ethibond can substitute for stainless steel wire in situations where a compliant repair is suitable (support of a patellar tendon repair), but may not be satisfactory for rigid fixation (tension band fixation of a fracture). There appears to be no significant difference in strength but a small decrease in stiffness between tying multiple suture loops in one knot as opposed to individual knots.

Revision anterior cruciate ligament reconstruction

Revision ACL surgery is indicated in patients who present with pathologic anterior laxity on clinical examination that reproduces their symptoms of instability during activities of daily living or athletic activities. The goals of the revision ACL surgery are to stabilize the knee, prevent further injury to the articular cartilage and menisci, and maximize the patient's function. Successful revision ACL surgery requires a thorough preoperative evaluation, including a detailed history, physical examination, and radiographic evaluation. Preoperative planning begins with a determination of the mechanisms of failure for the initial ACL reconstruction. Often a primary, as well as secondary cause, for failure can be identified. The determination of the cause of failure is the first step in a carefully-constructed treatment plan, which includes consideration of skin incisions to be used, method of graft removal, hardware removal, the need for a staged procedure or concomitant surgery, graft material selection, tunnel placement, graft fixation, and postoperative rehabilitation protocol. Despite the most meticulous planning, unanticipated findings may be encountered in the operating room, and the preoperative plan should have enough flexibility to accommodate these developments. Finally, it is crucial to counsel the patient preoperatively to limit his or her expectations regarding their surgical outcome. Given the complexity of revision ACL reconstruction, patient expectations must be adjusted to realistically match the potential for success. With proper planning, attention to detail, and appropriate patient expectations, revision ACL surgery can result in a beneficial and satisfying patient outcome.

Bone-patellar tendon-bone grafts for anterior cruciate ligament reconstruction: an in vitro comparison of mechanical behavior under failure tensile loading and cyclic submaximal tensile loading

BACKGROUND

Secure fixation is an important factor in the success of anterior cruciate ligament reconstruction.

HYPOTHESIS

There is no difference in the mechanical behavior of reconstructions from method of fixation or method of testing.

STUDY DESIGN

Controlled laboratory study.

METHODS

Anterior cruciate ligament reconstructions were performed with bone-patellar tendon-bone grafts in 48 human cadaveric knees. Three different fixation methods (Endobutton, interference screw, suture-post fixation) were compared under failure tensile loading and cyclic submaximal tensile loading.

RESULTS

No difference was observed in ultimate load among the three techniques. Stiffness of the grafts was significantly lower for the suture technique than for the interference screw technique. Cyclic loading revealed significantly different failure rates: 0% of the Endobutton, 38% of the interference screw, and 100% of the suture-post groups. The relative movement of the femoral bone plug and the migration of the bone plug out of the femoral canal were lowest in the interference screw group.

CONCLUSIONS

The suture-post fixation is not recommended. The interference screw technique showed the best results, but results were age-dependent, suggesting its best use is in younger patients. The Endobutton technique is recommended for older patients.

CLINICAL RELEVANCE

Results of testing are useful to the surgeon in making a choice of reconstruction technique.

Mechanical behavior of two hamstring graft constructs for reconstruction of the anterior cruciate ligament

We compared the mechanical behavior of two common hamstring graft constructs that are frequently used for reconstruction of the anterior cruciate ligament-Graft A: quadrupled semitendinosus tendon fixed with titanium button/polyester tape and suture/screw post, and Graft B: a double semitendinosus and double gracilis tendon fixed with a cross pin and two screws over washers. The experimental protocol used to evaluate each graft construct included stress relaxation (with and without preconditioning), cyclic loading, and a tensile load-to-failure test. The amount of stress relaxation without preconditioning was 60.6% for Graft A and 53.8% for Graft B. With preconditioning, it significantly decreased (p < 0.05) to 48.7 and 42.3%, respectively. Elongation of the graft construct in response to 100 cycles of loading (20-150 N) was 1.8 and 0.6% of the original length for Grafts A and B, respectively. However, after a series of five cyclic loading tests, the residual permanent elongation for each construct was 3.8 +/- 1.2 and 0.3 +/- 0.2 mm, a significant difference (p < 0.05) between the two graft constructs. Further analysis found more than 90% of the permanent elongation in the proximal and distal regions of Graft A, which consisted of polyester tape tied to a titanium button (proximal) and sutures tied around a screw post (distal). The tensile load-to-failure tests also revealed significant differences (p < 0.05) between the two graft constructs. Linear stiffness was 32 +/- 1 and 119 +/- 19 Nmm and ultimate load was 415 +/- 36 and 658 +/- 128 N for Grafts A and B, respectively. For Graft A, the polyester tape consistently failed; for Graft B, slippage or tearing from the washers was the mode of failure. We conclude that a quadruple-hamstring graft fixed over a cross pin proximally and with metal washers distally (Graft B) has less permanent elongation in response to cyclic loading and has structural properties superior to those of a graft construct that includes suture and tape material (Graft A). The large permanent elongation following repetitive loading of a graft construct with tape and suture material during the early postoperative period is of concern.

Current trends in anterior cruciate ligament reconstruction. Part 1: Biology and biomechanics of reconstruction

With today's increasing emphasis on sporting activities, the incidence of anterior cruciate ligament injuries has also increased. Epidemiologic studies estimate that the prevalence of anterior cruciate ligament injuries is about 1 per 3000 Americans. Management of these injuries has evolved from nonoperative treatment to extracapsular augmentation and primary ligament repair to anterior cruciate ligament reconstruction. Treatment of these injuries has significantly improved over the last few decades with the application of knowledge gained from both basic science and clinical research. This article is composed of two parts. The first part reviews the biology and biomechanics of the injured anterior cruciate ligament and the basic science of reconstruction. In the second part, to be published later, current operative concepts of reconstruction, as well as clinical correlations, are reviewed. Summarizing the latest information on basic scientific as well as clinical studies regarding the anterior cruciate ligament, this article intends to demonstrate the correlation between the application of basic science knowledge and improvement of clinical outcomes.

Structural properties of sutures used in anchoring multistranded hamstrings in anterior cruciate ligament reconstruction: a biomechanical study

Sutures are frequently used in anchoring hamstring or quadriceps tendon grafts in cruciate ligament reconstruction. Trumpet like widening of the femoral bone canal was found in patients having had anterior cruciate ligament reconstruction with hamstring autograft. We investigated 5-mm Polylene tape (Genzyme, Boston, MA) and Mersilene tape (Ethicon, Somerville, NJ) as well as No. 6 Ethibond sutures (Ethicon) for ultimate load, stiffness, and elongation under tension of 50 N, 150 N, 250 N, and ultimate load. The Mersilene and Polylene tapes were tested in single loops and Ethibond in double loops having a length of 30 mm. The length is similar to that used intraoperatively for the graft fixation. The suture materials were loaded using a material testing machine at a strain rate of 60 mm/min. The ultimate loads of the loops with knots were 474 N +/-24.7 N for Polylene, 437 N +/-38.2 N for Mersilene, and 338 N +/-16.8 N for Ethibond, and was statistically significant (analysis of variance [ANOVA], P<.05). The elongation under a tension load of 50 N was similar for Ethibond (1.2+/-0.216 mm) and Polylene (1.3+/-0.32 mm). Mersilene (1.7+/-0.34 mm) showed an increased elongation (ANOVA, P=.03). The stiffness for Ethibond was 37.1+/-2.7 N/mm, for Mersilene 38.4+/-3.8 N/mm, and for Polylene was 47+/-3.1 N/mm. The Polylene tape appears to be the most suitable material in terms of strength and stiffness. Nevertheless, the stiffness of all the tested materials is greatly inferior to the stiffness of the commonly used grafts. We believe that a stiffer graft construct might reduce motion during the early period of ingrowing.