Analysis of initial fixation strength of press-fit fixation technique in anterior cruciate ligament reconstruction

We performed a controlled laboratory study to evaluate the initial fixation strength of press-fit technique. Forty porcine lower limbs were used and divided into four groups according to the method of fixation; group 1 (press-fit+1.4 mm), in which the diameter difference between the bone plug and the femoral tunnel was 1.4 mm; group 2 (press-fit+1.4 mm, 30 degrees), in which the diameter difference was the same with group 1, but the tensile loading axis was 30 degrees away from the long axis of the femoral tunnel; group 3 (titanium), in which a titanium interference screw was used for fixation; group 4 (bioabsorbable), in which a bioabsorbable interference screw was used for fixation. The graft in the press-fit group was harvested with a hollow oscillating saw with inner diameter of 9.4 mm to obtain consistent and completely circular shape of the bone plug. The femoral tunnel with diameter of 8 mm was drilled at the original ACL insertion. Following the bone plug insertion into the femoral tunnel and applying a preload of 20 N, the specimen underwent 500 loading cycles between 0 and 2 mm of displacement. Thereafter the specimen was loaded to failure. There was no fixation site failure during the cyclic loading test. Significant differences in the stiffness, linear load, or failure mode among the groups were not found. The average ultimate failure load of group 1 and group 2 were not significantly different from those of group 3 and group 4. The press-fit groups demonstrated sufficient fixation strength for the rehabilitation and interference screw groups. The completely circular shape of the bone plug and increased diameter difference between the bone plug and the femoral tunnel seemed to contribute to the strong fixation.     

A biomechanical comparison of initial fixation strength of 3 different methods of anterior cruciate ligament soft tissue graft tibial fixation: resistance to monotonic and cyclic loading

BACKGROUND: Tibial fixation of soft tissue grafts continues to be problematic in the early postoperative period after anterior cruciate ligament reconstruction. HYPOTHESIS: No differences exist for resistance to slippage of soft tissue grafts fixed with CentraLoc, Intrafix, or 35-mm bioabsorbable interference screws. STUDY DESIGN: Controlled laboratory study. METHODS: Bovine tibia and hoof extensor tendons were divided into 3 matched groups with 12 tibia and 12 extensor tendons in each group. Within each group, 6 specimens underwent monotonic loading to failure (1 mm/s), and 6 underwent cyclic loading (10,000 cycles, 125-325 N, 1 Hz). RESULTS: No statistically significant differences were noted in mean load to failure or stiffness. The mean load to failure (and stiffness) for the 3 types of fixation were as follows: bioabsorbable interference screw, 631.6 +/- 130.1 N (88.17 +/- 6.79 N/mm); Intrafix, 644.3 +/- 195.2 N (81.65 +/- 16.5 N/mm); and CentraLoc, 791.1 +/- 72.7 N (77.89 +/- 7.07 N/mm). The slippage rates under cyclic loading for the 3 types of fixation were bioabsorbable interference screw, 0.336 +/- 0.074 microm/cycle; Intrafix, 27.2 +/- 31.6 microm/cycle; and CentraLoc, 0.0355 +/- 0.0046 microm/cycle. In this model, CentraLoc proved statistically superior in resistance to cyclic loading compared with the bioabsorbable interference screw (P < .05) and Intrafix (P < .0001). The bioabsorbable interference screw proved statistically superior to Intrafix in resistance to cyclic loading (P < .05). CONCLUSIONS: In this bovine model, CentraLoc and bioabsorbable interference screws provided superior resistance to cyclic loading compared with Intrafix. CLINICAL RELEVANCE: CentraLoc and bioabsorbable interference screws showed superior resistance to cyclic loading, which may indicate an increased resistance to clinical failure.     

Initial fixation strength of a hybrid technique for femoral ACL graft fixation

Aperture fixation with interference screws matching the diameter of the tunnel is associated with the risk of graft laceration and graft rotation. A hybrid fixation technique (extracortical and aperture fixation) with undersized interference screws provides a higher fixation strength when compared to an aperture fixation using only a screw matching the size of the tunnel and also reduces the risk of graft laceration. This research is an experimental laboratory study. We evaluated the initial fixation strength at time-zero of an extracortical-, a hybrid- and an aperture fixation in ACL reconstruction using extracortical buttons and different sized interference screws in porcine knees. The tests were performed using a single cycle and cyclic loading protocol. Analysis of yield load, maximum load and stiffness in the single cycle loading test showed no statistically significant differences for hybrid fixation with a 1 mm undersized screw and aperture fixation with a screw matching the size of the tunnel. Cyclic loading tests showed a statistically significant difference between hybrid and aperture fixation. The use of an undersized screw alone in aperture fixation resulted in insufficient fixation strength. The initial fixation strength of the hybrid technique with undersized screws is higher compared to an interference screw fixation alone. The hybrid fixation technique is an alternative for ACL graft fixation.     

Interference screw fixation of soft tissue grafts in anterior cruciate ligament reconstruction: part 1: effect of tunnel compaction by serial dilators versus extraction drilling on the initial fixation strength

BACKGROUND: Compaction of the bone-tunnel walls by serial dilation is believed to enhance the interference screw fixation strength of the soft tissue grafts in anterior cruciate ligament (ACL) reconstruction. HYPOTHESIS: Serial dilation enhances the fixation strength of soft tissue grafts in ACL reconstruction over extraction drilling. STUDY DESIGN: Randomized experimental study. METHODS: Initial fixation strength of the doubled anterior tibialis tendon grafts (fixed with a bioabsorbable interference screw) was assessed in 21 pairs of human cadaver tibiae with either serially dilated or extraction-drilled bone tunnels. The specimens were subjected to a cyclic-loading test, and those surviving were then tested using the single-cycle load-to-failure test. RESULTS: During the cyclic-loading test, there were 3 fixation failures in the serially dilated and 6 failures in the extraction-drilled specimens but no significant stiffness or displacement differences between the groups. In the subsequent load-to-failure test, the average yield loads were 473 +/- 110 N and 480 +/- 115 N for the 2 groups respectively (P =.97) and no difference with regard to stiffness or mode of failure. CONCLUSIONS: Serial dilation does not increase the strength of interference fixation of soft tissue grafts in ACL reconstruction over extraction drilling. Clinical Relevance: The results of this experiment do not support the use of serial dilators in ACL reconstruction.     

The role of maximal strength and load on initial power production

PURPOSE: The influence of maximal strength, as measured by the maximal load lifted for one repetition (1RM), on power production in the initial 200 ms of the concentric phase for both rebound and nonrebound movements was investigated. We also investigated the effect of external load upon this relationship. METHODS: Twenty-seven male subjects (21.9 +/- 3.1 yr, 89.0 +/- 12.5 kg) were separated by previously determined bench press IRM into high (100.88 +/- 7.24 kg) and low (72 +/- 6.61 kg) RM groups. Concentric only bench presses and rebound bench presses were compared between and within groups to note the effect of RM across external loads of 40%, 60%, and 80% 1RM, on instantaneous, mean, and peak power output. RESULTS: The results of this study clearly indicated the enhancement of concentric motion by prior eccentric muscle action (336-1332% enhancement in the first 20 ms). Possessing a high RM augmented power production in the initial 200 ms of stretch-shorten cycle activity, across all the external resistances tested (P < 0.05). The temporal characteristics of this enhancement, however, differed across loads. That is, 80% IRM loading showed a later time to peak enhancement (80 ms vs 20 ms). Interestingly, the influence of RM on concentric only motion in the initial 200 ms across the external resistances tested was found to be nonsignificant. CONCLUSIONS: The results suggest that the role of maximal strength during initial power production between concentric and stretch-shorten cycle activity differs, which has important implications for the training of athletes.     

The fixation strength of tibial PCL press-fit reconstructions

Purpose  

A secure tibial press-fit technique in posterior cruciate ligament reconstructions is an interesting technique because no hardware is necessary. For anterior cruciate ligament (ACL) reconstruction, a few press-fit procedures have been published. Up to the present point, no biomechanical data exist for a tibial press-fit posterior cruciate ligament (PCL) reconstruction. The purpose of this study was to characterize a press-fit procedure for PCL reconstruction that is biomechanically equivalent to an interference screw fixation.     

Pullout failure strength of the posterior horn of the medial meniscus with root ligament tear

Purpose

To evaluate the reparability of the posterior horn of the medial meniscus with root ligament tear by measuring the actual pullout failure strength of a simple vertical suture of an arthroscopic subtotal meniscectomized posterior horn of the medial meniscus.

Methods

From November 2009 to May 2010, nine posterior horns of the medial meniscus specimens were collected from arthroscopic subtotal meniscectomy performed as a treatment for root ligament rupture of the posterior horn of the medial meniscus. Simple vertical sutures were performed on the specimens, and pullout failure load was tested with a biaxial servohydraulic testing machine (Model 8874; Instron Corp., Norwood, MA, USA). The degree of degeneration, extrusion, and medial displacement of the medial meniscus were evaluated with magnetic resonance imaging (MRI). The Kellgren–Lawrence classification was used in standing plain radiography, and mechanical alignment was measured using orthoroentgenography. Tear morphology was classified into ligament proper type or meniscoligamentous junctional type according to the site of the torn root ligament of the posterior horn of the medial meniscus during arthroscopy.

Results

The mean pullout failure strength of the posterior horn of the medial meniscus was 71.6 ± 23.2 N (range, 41.4–107.7 N). The degree of degeneration of the posterior horn of the medial meniscus on MRI showed statistically significant correlation with pullout failure strength and Kellgren–Lawrence classification. Pullout failure strength showed correlation with mechanical alignment and Kellgren–Lawrence classification (P < 0.05).

Conclusions

The measurement of pullout failure strength of the posterior horn of the medial meniscus with root ligament tear showed a degree of repairability. The degree of degeneration of the posterior horn of the medial meniscus on MRI showed a significant correlation with the pullout failure strength. The pullout failure strength was also not only correlated with the degree of degeneration of the posterior horn of the medial meniscus, but also with mechanical alignment and Kellgren-Lawrence classification, which represent bony degenerative change.     

跟骨骨折外固定技术的发展

20世纪以来,足踝外科领域对于跟骨骨折的处理逐渐成熟,但是内固定技术一直存在内植物占位以及切口皮肤感染等问题。外固定技术为上述问题提供了解决方案,使用外固定处理开放性跟骨骨折以及软组织条件差的闭合性跟骨骨折具有诸多优势。临床上应用外固定技术对跟骨骨折的治疗早已开展,然而外固定治疗跟骨骨折的相关文献却很少。本文就跟骨骨折应用外固定技术治疗的历史及方法作一综述,理清其优劣,便于临床医师选择及制定手术方案、治疗策略。     

Biomechanical characterization of double-bundle femoral press-fit fixation techniques

Purpose  

Press-fit fixation of patellar tendon bone anterior cruciate ligament autografts is an interesting technique because no hardware is necessary. To date, no biomechanical data exist describing an implant-free double-bundle press-fit procedure. The purpose of this study was to characterize the biomechanical properties of three double-bundle press-fit fixations.     

Initial fixation strength of interference nail fixation for anterior cruciate ligament reconstruction with patellar tendon graft (experimental study)

The objective of this study was to evaluate initial fixation strength of a new interference nail fixation in anterior cruciate ligament reconstruction using bone-patellar tendon-bone graft. Human cadaver knees were used. Fixation strengths ranged from 500 N to 600 N (mean 550 N). This corresponds to loads in the graft during aggressive rehabilitation. No slippage occurred at fixation site of specimens. Most of the failures appeared from the femoral side with tendon ruptures. With respect to primary fixation strength, interference nail fixation is a reasonable alternative for anterior cruciate ligament reconstruction with bone-patellar tendon-bone graft.     

Compaction drilling does not increase the initial fixation strength of the hamstring tendon graft in anterior cruciate ligament reconstruction in a cadaver model

BACKGROUND: Compaction of the bone tunnel walls has been proposed to increase the fixation strength of soft tissue grafts fixed with an interference screw in anterior cruciate ligament reconstructions. HYPOTHESIS: Compaction drilling does not increase the initial fixation strength of the hamstring tendon graft in comparison with conventional extraction drilling. STUDY DESIGN: Randomized experimental study. METHODS: Initial fixation strength of quadrupled hamstring tendon grafts fixed with bioabsorbable interference screws was assessed in 22 pairs of human cadaveric tibiae. Bone tunnels were drilled with either a compaction drill or a conventional extraction drill. Specimens underwent a cyclic-loading test and the surviving specimens were then loaded to failure in a single-cycle load-to-failure test. Trabecular bone mineral density at the site corresponding to the actual site of the tibial bone tunnel was determined by using peripheral quantitative computed tomography. RESULTS: During the cyclic-loading test, no significant stiffness or displacement differences were observed between the two drilling techniques. Three specimens failed in the compaction-drilling group, whereas there were no failures in the extraction-drilling group. In the subsequent single-cycle load-to-failure test, no significant differences between the two drilling techniques were found with regard to displacement at yield load, stiffness, or mode of failure. There was no significant difference in trabecular bone mineral density between the two groups. CONCLUSIONS: Compaction drilling does not increase the initial fixation strength of the hamstring tendon graft compared with conventional extraction drilling.     

桥接组合式内固定系统治疗股骨髁间粉碎性骨折

目的探讨桥接组合式固定系统治疗股骨髁间粉碎性骨折的临床效果。方法回顾性分析解放军59中心医院骨关节外科2014年5月-2016年9月使用桥接组合式内固定系统治疗的10例股骨髁间骨折患者,其中男性7例,女性3例;年龄19~60岁,平均45岁。致伤原因:道路交通伤6例,高处跌伤4例。骨折Müller AO分型为:33-C2 6例,33-C3 4例。评估手术时间、出血量及患肢功能恢复情况。结果 10例获随访12~30个月(平均19个月),手术时间1~2h(平均1.6h),出血量200~400mL(平均250mL),随访期间手术切口愈合良好,内固定无松动及断裂等并发症。术后Sanders肢体评价:优7例,良2例,可1例,优良率90%。结论使用桥接组合式固定系统治疗股骨髁间粉碎性骨折符合生物学固定原则,术中操作简单,临床效果满意,是治疗股骨髁间粉碎性骨折的一种新的内固定装置。     

Evaluation of techniques for intravenous catheter and tubing fixation

OBJECTIVE: The aim of this study was to examine two techniques intended to prevent accidental displacement of intravenous catheters after proper establishment of infusion line access. METHODS: After catheter insertion and taping in position, fixation with gauze roll sequentially wrapped around the limb across which the tubing has been extended was compared with the use of a polyethylene roll manipulated by an attached "handle." The experimentation was performed on medical personnel serving as live models. RESULTS: Thirty-eight trials were conducted with 19 of each fixation technique. The variables measured were: time consumption, convenience, general satisfaction, and success score of the fixation. All of the measurements showed that the polyethylene roll was significantly the superior of the two methods. Despite forceful tugging of the tubing, polyethylene fixation virtually prevented any displacement whatsoever and was more than twice as rapid. CONCLUSIONS: We demonstrate a novel device allowing faster and more efficacious fixation of the infusion drip tubing and catheter suggested as the technique of choice in emergency medical field care.     

Isokinetic muscle strength and knee function associated with double femoral pin fixation and fixation with interference screw in anterior cruciate ligament reconstruction

Purpose  

Intensive scheduling in sports requires athletes to resume physical activity shortly after injury. The purpose of this study was to investigate early isokinetic muscle strength and knee function on bone-patellar tendon-bone (BPTB) ACL reconstruction with double femoral pin fixation or interference screw technique.     

记忆合金环抱器固定肋骨骨折的适应证及手术技巧

目的 评价记忆合金环抱器固定肋骨骨折的临床效果,探讨该术式的手术适应证及手术技巧.方法 回顾性总结2010年10月-2011年4月应用记忆合金环抱器治疗的肋骨骨折患者30例的临床资料.统计记忆合金环抱式固定器的使用数量、固定部位、手术时间,对比患者术前、术后的疼痛评分,分析手术疗效及并发症情况.结果 30例患者手术时间(111.9±48.0)min,使用固定器(4.3±2.1)个,固定肋骨(3.5±1.3)根.术前疼痛评分(6.93±0.88)分,术后疼痛评分(4.04±0.62)分(P＜0.05).下床活动时间(4.6±1.9)d,住院时间(27.2±10.8)d.术后出现切口、胸壁血肿3例,肺部感染6例,无顽固性胸痛、异物排斥反应或切口感染.结论 记忆合金环抱器固定肋骨骨折可明显减轻患者疼痛、改善肺功能、减少呼吸机应用时间及肺部感染等并发症的发生.     

髌骨-胫骨结节架桥式固定治疗髌骨下极骨折

目的　探讨髌骨下极骨折的可靠内固定方法。方法　自 1998～ 2 0 0 1年开展髌骨 -胫骨结节架桥式内固定 (以下简称桥式手术 )治疗髌骨下极骨折 2 4例 ,均为新鲜性骨折 ,开放性骨折 2例。结果　手术后平均随访 8个月 ,伤口均一期愈合 ,骨折愈合时间平均 7周 ,优良率达 91.7%。结论　采用桥式手术治疗髌骨下极骨折 ,内固定坚强 ,操作简便 ,骨折愈合快 ;可早期功能锻炼 ,并发症少 ,为髌骨下极粉碎性骨折难以维持复位的病人提供了一种完整保留髌骨的可靠方法     

Anatomical two-bundle medial patellofemoral ligament reconstruction with hardware-free patellar graft fixation: technical note and preliminary results

Purpose

Various techniques for reconstruction of the medial patellofemoral ligament (MPFL) have been developed. In this article, a modified technique for anatomical two-bundle MPFL reconstruction with hardware-free patellar graft fixation is described and the preliminary results of this technique are presented.

Methods

A modified surgical technique for MPFL reconstruction with a gracilis tendon autograft and hardware-free patellar graft fixation using two short oblique bone tunnels is described in detail. Complications and preliminary results of this procedure were assessed in 19 patients at a mean follow-up of 16 ± 3 months using the Kujala score, Tegner scale, and Insall score.

Results

No postoperative patellar dislocation or subluxation was reported. Eighty-nine per cent of the patients were either satisfied or very satisfied with the overall outcome. The mean Kujala score was 92 ± 7 (range 69–100), and the median Tegner scale was 5 (range 3–7). According to the Insall score, the results of 18 patients (95 %) were rated as good or excellent. Postoperative complications occurred in 3 patients (16 %), with two of them persisting only temporary.

Conclusions

The described technique for anatomical two-bundle MPFL reconstruction is a safe and effective surgical procedure for the treatment of lateral patellar instability, with several methodical advantages compared to similar techniques. Further evaluation in a larger patient cohort with a longer follow-up is necessary to confirm these short-term results.

Level of evidence

IV.     

Failure strength of repair devices versus meniscus suturing techniques

The purpose of this study was to compare the load to failure of different common suturing techniques with repair devices. Seventy-one calf medial menisci were cut to simulate peripheral longitudinal tears and repaired with one of 13 repair techniques. The two parts of the meniscus were pulled using the Instron tensometer until failure occurred. The techniques and repair devices tested were vertical (0 PDS, 2-0 PDS, 2-0 Ethibond), horizontal (0 PDS, 2-0 PDS, 2-0 Ethibond) suturing, T-fix, Mitek, Clearfix screw, Clearfix dart, Biostinger, S-D-sorb, and Artrex dart. The strongest repair method in our study was the vertical sutures with 0 PDS. In this study the mean failure strength of all meniscal repair devices was lower than that of the vertical and horizontal suturing techniques. All meniscus repair devices except T-fix and in some the Arthrex dart (40% broken up) pulled out of the menisci. Devices which had only horizontally placed barbs had lower mean failure strength. Failure strength of T-fix was similar to horizontal sutures with 2-0 Ethibond and 2-0 PDS. In conclusion, because all meniscal repair devices had inferior results, when such devices are used, postoperative rehabilitation should not be hastened, and their inferior primary stability should be kept in mind.