Does thread shape affect the fixation strength of the bioabsorbable interference screws for anterior cruciate ligament reconstructions? A biomechanical study (original) (raw)
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Bioabsorbable Interference Screws for Graft Fixation in Anterior Cruciate Ligament Reconstruction
Arthroscopy: The Journal of Arthroscopic & Related Surgery, 1999
The central one third of the patellar tendon autograft is popular because the bone-tendon-bone (BTB) construct provides several graft fixation options, robust graft incorporation, and a mechanically sufficient substitute. Interference screw fixation is one method used to secure the graft. Bioabsorbable interference screws may offer advantages over metal interference screws. Bioabsorbable screws are made from poly L-lactic acid (PLLA) and are absorbed by the body. This prospective, randomized study compared the safety and efficacy of the PLLA screw with that of the metal cannulated interference screw for anterior cruciate ligament reconstruction. There were 204 patients randomly assigned to the Bioscrew (Linvatec, Largo, FL) (n ϭ 103) or the metal interference screw (n ϭ 101) groups at four sites. The mean age was 30 years. There were 66 women and 138 men. Mean follow-up was 30 months for Bioscrews and 28 months for metal screws; the average follow-up interval was 2.4 years. The Lysholm mean scores at 4 years for the 32 patients seen at this interval were 95.0 and 97.2 for the Bioscrew and metal screw group, respectively. Ligament laxity comparisons made with an instrumented arthrometer at manual maximum force resulted in side-to-side mean score differences of B ϭ 1.8mm and M ϭ 1.6mm. The Tegner activity level score means were B ϭ 6.1 and M ϭ 5.8. Other variables examined included pain, thigh size, meniscal tests, Lachman's test, range of motion, anterior drawer, pivot shift, patellofemoral crepitus and tenderness, and joint effusion. None of these variables showed a statistically significant difference between groups. No radiographic evidence of osteolytic change or bone resorption around the Bioscrews was observed. There were no complications related to loss of fixation, toxicity, allergenicity, or other evidence of osteolytic or inflammatory reaction. In every assessment between groups there was no difference found. There were 12 PLLA screws that broke during insertion without any adverse effects. The PLLA headless cannulated interference fit screws produce equal results to similarly designed metal screws.
Failure strength of bioabsorbable interference screws: effects of in vivo degradation for 12 weeks
Knee Surgery Sports Traumatology Arthroscopy, 2003
We investigated the effect of in vivo degradation for 6–12 weeks on the fixation strength of polylactide bioabsorbable interference screws. Ten bioabsorbable interference screws were used to fix the patellar tendon autograft in ten live sheep knees, which were equally divided into two groups and killed in the 6th or 12th week. The control group consisted of four cadaveric knees. Following the killing of the animals the screws were retrieved and reused to fix patellar tendon grafts in cadaveric sheep knees. Tendon pull-out tests were performed for the partially degraded screws, for the control group, and for the reused screws of the control group. Macroscopic and microscopic examinations of the 6- and 12-week specimens were performed. Tendons pulled-out with an average force of 357±30 N in the cadaveric control group on the first use and with 465±118 N on the second use. The partially degraded screws failed with a mean load of 399±119 N in the 6-week group, and 12-week screws at 447±72 N. No macroscopic sign of degradation was observed on the retrieved screws. Histological examination of the 6 week specimens showed necrotic changes in the tendon around screw contact areas. Healing with granulation tissue was present in the same area in the 12th week. Foreign body reaction or an excessive inflammatory reaction was not observed. In vivo degradation of poly-l-lactide interference screws for 12 weeks thus causes neither a loss in the fixation strength of the screws nor an obvious inflammatory reaction.
International Orthopaedics, 2007
Comparison of the results of bioabsorbable interference screws and posts for hamstring graft distal fixation in ACL reconstructions are presented. The results of 20 patients with bioabsorbable screws were compared to 22 patients with posts. The assessement was based on Lysholm-Gillquist and Marshall scores and the KT-1000 device. In the study group the points gained were 38.9 in the Lysholm-Gillquist and 12.89 in the Marshall scale. The average KT-1000 difference was 2.46 mm. In the control group the points gained were 32.93 in the Lysholm-Gillquist and 11.47 in the Marshall scale. The average KT-1000 difference was 2.5 mm. There were 14 patients in the study group with interference screw problems; in 2 the implants were removed. (1) There are no differences in outcome using bioabsorbable interference screws and posts for distal fixation of hamstring ACL grafts. (2) The lack of bioabsorbtion with poly L-lactide interference screws is frequent and causes problems. Résumé Le but de cette étude est de comparer les résultats d'une vis d'interférence résorbable ou non résorbable dans la fixation des muscles ischio-jambiers pour la reconstruction du LCA. Les résultats de 20 patients avec vis d'interférence résorbable ont été comparés à 22 patients avec vis non résorbable. Les résultats ont été évalués selon le score de Lysholm et Gillquist, le score de Marshall et l'appareil KT-1000. Dans le groupe d'étude, l'amélioration du score a été de 38.9 pour Lysholm-Gillquist et de 12.89 avec la méthode de Marshall, avec une différence de 2.46 mm avec l'appareillage KT-1000. Dans le groupe contrôle, l'amélioration a été de 32.93 avec la méthode Lysholm-Gillquist et de 11.47 avec la méthode de Marshall, la différence avec KT-1000 de 2.5 mm. Il y avait 14 patients dans le groupe d'étude avec vis d'interférence et deux implants ont dû être enlevé. Il n'y a pas de différence significative que l'on utilise ou non des vis d'interférence biorésorbable. Avec ces vis d'interférence poly L-Lactide biorésorbable leur résorption est fréquente et peut être source de problèmes.
Arthroscopy: The Journal of Arthroscopic & Related Surgery, 2005
The aim of this study was to compare ultimate load, yield load, stiffness, and displacement after cyclic loading of a cross-pin technique and an interference screw technique for the fixation of bone-patellar tendon-bone (BPTB) grafts in anterior cruciate ligament (ACL) reconstruction. Type of Study: Biomechanical in vitro study. Methods: The devices tested were 2 2.7-mm biodegradable pins (RigidFix; Ethicon, Mitek Division, Norderstedt, Germany) and biodegradable interference screws (Absolute; Innovasive Devices, Marlborough, MA). Each device was used for the fixation of 10 8-mm, 9-mm, or 10-mm sized human BPTB grafts in tunnels drilled in bovine knees. Ultimate load, yield load, stiffness, and displacement after cyclic loading (1,000 cycles between 50 and 250 N) were then evaluated. Results: All 8-mm grafts that were fixed with cross-pins failed after a mean of 124 cycles of load. The 9-mm and 10-mm grafts survived the cyclic loading protocol. Yield load and maximum load of the 10-mm groups (cross-pin and interference screw) were significantly higher than that of the 9-mm groups. There was no significant difference in maximum load, yield load, and stiffness between the cross-pin and interference screw fixation technique for 1 graft size. Conclusions: The biomechanical data suggest that femoral fixation of 9-mm and 10-mm BPTB grafts using 2.7-mm biodegradable cross-pins leads to primary stability that is comparable to that of biodegradable interference screws. Fixation of 8-mm BPTB grafts using 2.7-mm biodegradable cross-pins had poor results. Clinical Relevance: The diameter of the bone block is the limiting factor for the final fixation strength and the cyclical survival when using cross-pins. We strongly recommend not using this technique for bone blocks smaller than 9 mm in diameter.
Archives of Orthopaedic and Trauma Surgery, 2010
Introduction The application of interference screws for the Wxation of bone-patellar tendon-bone (BPTB) grafts is a well-established technique in anterior-cruciate ligament reconstruction. Interference screws derived from bovine compact bone are a biological alternative to metallic or biodegradable polymer interference screws. Materials and methods In 60 porcine specimens, the tibial part of an anterior-cruciate ligament reconstruction was performed using a BPTB graft. To secure the graft, either an 8-mm titanium interference screw or a self-made bovine interference screw (BC), or a commercial bovine compact bone screw (TutoWx ® ) was used. The maximum failure load was determined by means of a universal testing machine with computer interface at a testing speed of 50 mm/min. In a second test series, cyclic sub-maximal load was applied to the test specimen from 40 to 400 N with a number of 1,000 load cycles and a frequency of 1 Hz. Subsequently, the maximum failure load was determined. The stiVness of the test specimen was investigated in both test series. Each type of interference screw was tested 10 times.
Research on Biomedical Engineering, 2015
The rupture of the anterior cruciate ligament (ACL) is the most common type of knee injury. Reconstructive surgery is the 'gold standard' treatment. During the immediate post-operative period, the fixation of the graft is entirely dependent on the ability of the grafted implant to be secured inside the bone tunnel under the cyclical loads associated with daily tasks. Poor fixation can lead to graft slippage, thus impairing the healing and integration of the graft. The aim of this study was to evaluate the biomechanical performance of tendon graft fixation devices with metallic and bioabsorbable interference screws. Methods: Twenty ACL reconstructions were carried out in porcine tibias using deep flexor tendons to fix 9 × 20 mm metallic (n=10) and PLLA 70/30 bioabsorbable screws (n=10). To verify the ability of a construct to resist immediate postoperative (PO) rehabilitation protocols for immediate load bearing, a cyclic loading test was applied with 50-250 N of tensile force at 1 Hz for 1000 cycles, and the displacement was measured at 10, 50, 100, 500 and 1000 load cycles to quantify the slippage of the graft during the test. After the cyclic loading test, a singlecycle load-to-failure test was applied. Results: The slippage of the graft using metallic screws did not differ (P = 0.616) from that observed when using bioabsorbable screws. Conclusion: The results obtained in this experiment indicate that metallic screws may promote a similar amount of graft slippage during low cyclic loading as bioabsorbable screws. Additionally, there was no difference in the biomechanical performance of these two types of screws during high failure loads.