Tendon graft fixation in ACL reconstructionIn vitro evaluation of bioabsorbable tenodesis screw

Background and purpose — There are very few data concerning the outcome after short-segment posterior stabilization and anterior spondylodesis with rib grafts in patients suffering from unstable thoracolumbar burst fractures. We have therefore investigated the clinical and radiographic outcome after posterior bisegmental instrumentation and monosegmental anterior spondylodesis using an autologous rib graft for unstable thoracolumbar burst fractures.

Patients and methods — This was a retrospective analysis of 32 consecutive patients at a single center. The monosegmental Cobb angle was measured preoperatively, postoperatively, then 6 and 12 months postoperatively, and also after implant removal. Anterior vertebral fusion was graded on conventional radiographs according to the criteria proposed by Molinari.

Results — Segmental kyphosis at the fracture site was corrected from a median of -20° (95% CI: -21.2 to -18.8) to -1.0° (95% CI: -2.7 to 0.7) postoperatively. 1 year after surgery, the segmental angle had decreased by a median of 2.0° (95% CI: 0.2 to 2.8). The spondylodesis fused in all patients, which was evident from incorporation and remodeling of the rib grafts. The median correction loss after implant removal was 0.0° (95% CI: -0.5 to 0.5). 26 of the 32 patients reported having no back complaints at the last follow-up (2 years postoperatively). 1 patient suffered from intercostal neuralgia, and 5 patients reported mild to moderate back pain.

Interpretation — Short-segment posterior instrumentation and anterior spondylodesis using an autologous rib graft resulted in sufficient correction of posttraumatic segmental kyphosis. There was no clinically relevant correction loss, and the majority of patients had no back complaints at the 2-year follow-up.     

Arthroscopic biceps tenodesis: A new technique using bioabsorbable interference screw fixation

Purpose: To report a new technique of arthroscopic biceps tenodesis using bioabsorbable interference screw fixation and the early results. Type of Study: Prospective, nonrandomized study. Methods: Technique: The principle of arthroscopic biceps tenodesis is simple: after biceps tenotomy, the tendon is exteriorized and doubled on a suture; the biceps tendon is then pulled into a humeral socket (7 or 8 mm × 25 mm) drilled at the top of the bicipital groove, and fixed using a bioabsorbable interference screw (8 or 9 mm × 25 mm) under arthroscopic control. Patients: 43 patients treated with this technique between 1997 and 1999 were followed-up for at least 1 year. The technique was indicated in 3 clinical situations: (1) with arthroscopic cuff repair (3 cases), (2) in case of isolated pathology of the biceps tendon with an intact cuff (6 cases), and (3) as an alternative to biceps tenotomy in patients with massive, degenerative and irreparable cuff tears (34 cases). The biceps pathology was tenosynovitis (4 cases), prerupture (15 cases), subluxation (11 cases), and luxation (13 cases). Results: The absolute Constant score improved from 43 points preoperatively to 79 points at review (P < .005). There was no loss of elbow movement and biceps strength was 90% of the strength of the other side. Two patients, operated on early in the series, presented with a rupture of the tenodesis. In both cases the bicipital tendon was very friable and the diameter of the screw proved to be insufficient (7 mm). No neurologic or vascular complications occurred. Conclusions: Arthroscopic biceps tenodesis using bioabsorbable screw fixation is technically possible and gives good clinical results. This technique can be used in cases of isolated pathologic biceps tendon or a cuff tear. A very thin, fragile, almost ruptured biceps tendon is the technical limit of this arthroscopic technique.     

Biomechanical evaluation of a bioabsorbable expansion bolt for hamstring graft fixation in ACL reconstruction: an experimental study in calf tibial bone

Introduction: The purpose of our study was to evaluate and compare the primary fixation strength of a novel bioabsorbable two shell expansion bolt (EB) with that of a well-established interference screw-fixation technique in hamstring reconstruction of the anterior cruciate ligament. Materials and methods: Thirty calf tibia plateaus (age 5–6 months) were assigned to three groups: In group I (n=10) triple-stranded hamstring grafts were fixed with titanium interference screws (7 mm thread / 8 mm head × 25 mm). Specimens of group II (n=10) received bioabsorbable poly-L-lactide interference screws (8×23 mm). In group III (n=10), the grafts were fixed using bioabsorbable poly-D,L-lactide expansion bolts (5.8/8.5/10 mm × 35 mm). The tensile axis was placed parallel to the bone tunnel. The construction was then loaded until failure under a displacement rate of 1 mm per second. Results: There were no significant differences concerning the maximum pullout force (group I: 357 N ± 61; group II: 326 N ± 92; group III: 343 N ± 55). In case of the expansion bolt, we found the stiffness to be higher (61 N/mm) when compared to group I (48 N/mm), and group II (52 N/mm) (P<0.01 I vs. III). Using interference screws, we were able to demonstrate a strong correlation between torque and pullout forces (group I: r ²=0.7; group II: r ²=0.92). Ruptures of the suturing material occurred only in groups I and II. Conclusion: We conclude that hamstring graft fixation, using the presented expansion bolt, demonstrates fixation strength similar to the established screw fixation and can therefore be regarded as a reasonable alternative fixation method. Especially, since some specific disadvantages of screw fixation can be prevented by application of the bolt fixation.     

MRI evaluation of the tibial tunnel/screw/tendon interface after ACL reconstruction using a bioabsorbable interference screw

This article describes the complex relationship between graft, bone, and biologic interference screw. Orthopedic surgeons have just begun to understand this complex biologic relationship. Clinical outcome measurements tell very little about the biology in bone tunnels.     

Tendon transfer fixation: comparing a tendon to tendon technique vs. bioabsorbable interference-fit screw fixation

Tendon transfer techniques in the foot and ankle are used for tendon ruptures, deformities, and instabilities. This fresh cadaver study compares the tendon fixation strength in 10 paired specimens by performing a tendon to tendon fixation technique or using 7 x 20-25 mm bioabsorbable interference-fit screw tendon fixation technique. Load at failure of the tendon to tendon fixation method averaged 279N (Standard Deviation 81N) and the bioabsorbable screw 148N (Standard Deviation 72N) [p = 0.0008]. Bioabsorbable interference-fit screws in these specimens show decreased fixation strength relative to the traditional fixation technique. However, the mean bioabsorbable screw fixation strength of 148N provides physiologic strength at the tendon-bone interface.     

Arthroscopic biceps tenodesis using a bioabsorbable interference screw

Arthroscopic biceps tenodesis has rarely been reported. The purpose of this study is to present our technique of arthroscopic biceps tenodesis using the Bio-Tenodesis (Arthrex, Naples, FL) screw system. This system uses a uniquely designed screwdriver that allows manipulation of the biceps tendon subacromially and intra-articularly, facilitates placement and maintenance of the biceps tendon at the base of the bone socket during interference screw insertion, and assures an adequate bone-tendon-screw interface.     

Magnetic resonance imaging analysis of the bioabsorbable Milagro™ interference screw for graft fixation in anterior cruciate ligament reconstruction

Ligament graft fixation with bioabsorbable interference screws is a standard procedure in cruciate ligament replacement. Previous screw designs may resorb incompletely, and can cause osteolysis and sterile cysts despite being implanted for several years. The aim of this study was to examine the in vivo degradation and biocompatibility of the new Milagro™ interference screw (Mitek, Norderstedt, Germany). The Milagro™ interference screw is made of 30% ß-TCP (TriCalcium phosphate) and 70% PLGA (Poly-lactic-co-glycolic acid). In the period between June 2005 and February 2006, 38 patients underwent graft fixation with Milagro™ screws in our hospital. Arthroscopic ACL reconstruction was performed using hamstring tendon grafts in all the patients. MR imaging was performed on 12 randomly selected patients out of the total of 38 at 3, 6 and 12 months after surgery. During the examination, the volume loss of the screw, tunnel enlargement, presence of osteolysis, fluid lines, edema and postoperative screw replacement by bone tissue were evaluated. There was no edema or signs of inflammation around the bone tunnels. At 3, 6 and 12 months, the tibial screws showed an average volume loss of 0, 8.1% (±7.9%) and 82.6% (±17.2%, P < 0.05), respectively. The femoral screws showed volume losses of 2.5% (±2.1%), 31.3% (±21.6%) and 92.02% (±6.3%, P < 0.05), respectively. The femoral tunnel enlargement was 47.4% (±43.8%) of the original bone tunnel volume after 12 months, and the mean tunnel volume of the tibial tunnel was −9.5% (±58.1%) compared to the original tunnel. Bone ingrowth was observed in all the patients. In conclusion, the resorption behaviour of the Milagro™ screw is closely linked to the graft healing process. The screws were rapidly resorbed after 6 months and, at 12 months, only the screw remnants were detectable. Moreover, the Milagro™ screw is biocompatible and osteoconductive, promoting bone ingrowth during resorption. Tunnel enlargement is not prevented in the first months but is reduced by bone ingrowth after 12 months.     

Interference screw fixation using bioabsorbable screw as void filler

We evaluated interference screw fixation in a plug-tunnel construct using bioabsorbable screws as void fillers with different percentages of the screw removed. Nine-millimeter tunnels in a closed-cell foam block were filled with a 10-mm bioabsorbable screw, and 10-mm revision tunnels were placed in parallel with tunnel overlap resulting in removal of 10%, 25%, or 50% of the screw diameter. Synthetic bone plugs were fashioned to fit 10-mm tunnels. In all groups, the plugs were secured in standard interference fixation with a 9-mm metal screw between the void-filling bioabsorbable screw and plug. Failure loads for the control group (no revision tunnel) averaged 926 +/- 44 N, 10% (1024 +/- 129 N) and 25% (932 +/- 129 N) groups were not significantly different; failure load in the 50% diameter group (780 +/- 72 N) was significantly lower than all other groups (p < 0.001). Using a bioabsorbable screw as void filler provided mean load to failure not different from that of standard reconstruction when 10 and 25% of the diameter of the void-filling screw was removed. Load to failure was significantly lower when 50% of the void-filling screw diameter group was removed. This may be applicable in anterior cruciate ligament reconstruction where a previous tunnel void has to be addressed.     

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.     

膨胀螺钉固定重建前交叉韧带的生物力学研究

背景:关节镜下重建前交叉韧带(ACL)的方法很多,且疗效较好。但目前尚无有关固定方法是否能提供坚强固定、恢复原有ACL生物力学特性的相关研究。目的:探讨股骨端膨胀界面螺钉固定腘绳肌腱移植重建ACL的生物力学。方法:取新鲜冰冻成人膝关节标本21具,采用4股腘绳肌腱移植重建ACL,股骨端分别使用膨胀界面螺钉(n=7)、可吸收界面螺钉(n=7)、金属界面螺钉(n=7)固定,测试循环载荷后位移、100 N位移、400 N位移、抗拉刚度、最大拔出载荷、失败模式以及肌腱切割程度等,并进行统计学分析。结果:循环载荷后位移:可吸收螺钉组<金属螺钉组<膨胀螺钉组,无统计学差异(P>0.05);最大拔出载荷:膨胀螺钉组>可吸收螺钉组>金属螺钉组,膨胀螺钉组与可吸收螺钉组比较无统计学差异(P>0.05),膨胀螺钉组与金属螺钉组比较有统计学差异(P<0.05);肌腱切割程度:膨胀螺钉切割伤最轻,可吸收螺钉次之,金属螺钉最重。结论:膨胀界面螺钉的最大拔出载荷、100 N位移、400 N位移以及抗拉刚度均超过普通界面螺钉,对移植肌腱损伤小,可以满足肌腱重建固定ACL的需要,并可实现单隧道ACL双束解剖重建。     

Graft failure versus graft fixation in ACL reconstruction: histological and immunohistochemical studies in rabbits

The causes of graft failure after anterior cruciate ligament (ACL) reconstruction are multifactorial including the methods of graft fixation. The purpose of this study was to examine the ACL graft failure in three different methods of graft fixations including interference screw fixation, suture-post fixation and combined interference screw and suture-post fixation. We hypothesized that the fixation method after ACL reconstruction can affect the graft healing in tibial tunnel. Eighteen New Zealand white rabbits were categorized into three groups according to the method of fixation in unilateral ACL reconstruction with long digital extensor autograft. Histological examination demonstrated that the combined fixation and suture-post fixation groups showed significantly better integration between tendon and bone (P = 0.04). In immunohistochemical analysis, the combined fixation and suture-post fixation groups showed significantly higher BMP-2 and VEGF expressions than interference screw (P < 0.01). The tendon–bone healing after ACL reconstruction was affected by the method of graft fixation. Combined fixation with interference screw and suture-post reduced graft-tunnel micromotion and improved the graft healing in tibial tunnel.     

Endopearl augmentation of bioabsorbable interference screw fixation of a soft tissue tendon graft in a tibial tunnel

In this technical note, we introduce a new technique for tibial side soft tissue graft fixation using a bioabsorbable interference screw augmented with an EndoPearl (Linvatec, Largo, FL) for ACL reconstruction. This technique will enable the knee surgeon to use shorter grafts while minimizing slippage without reducing fixation strength.     

Simulated graft recession in endoscopic ACL reconstruction: influence on graft strain

Eight fresh cadaveric knee specimens underwent arthroscopic-assisted ACL reconstruction to examine the influence of femoral graft recession on graft strain pattern. Length changes between tibial origin and femoral insertion (simulating graft strain or isometry pattern) were measured throughout knee motion (0 degrees-90 degrees) with a simulated ACL construct. Measurements were taken at the "endo" position (replicating the normal endoscopic position) and in progressive 1.5-mm increments proximally within the femoral tunnel (mimicking femoral graft recession). After recession up to a maximum of 15 mm, a block was placed anterior to the "recessed" graft construct (simulating placement of bone graft anterior to the recessed graft) and strain patterns were remeasured. Graft strain patterns were altered with as little as 1.5 mm recession in two of eight specimens. Compared to the "endo" position, all specimens showed a statistically significant decrease in strain by 3 mm of graft recession (P<.001 for 7 of 8, and P=.0138 for 1 of 8). A direct relationship exists between graft placement and ACL strain patterns, with more proximal graft "recession" adversely influencing normal graft strain. Bone graft placement anterior to the recessed graft restores strain patterns to those seen at the normal "endoscopic" position.     

Tibial and pretibial cyst formation after anterior cruciate ligament reconstruction with bioabsorbable interference screw fixation.

We report a case of an osteolytic tibial enlargement in association with a pretibial cyst formation 8 months after successful anterior cruciate ligament reconstruction with autologous bone-patellar tendon-bone graft and tibial graft fixation with a bioabsorbable interference screw. No joint inflammatory reaction or graft insufficiency was detected. The patient underwent cyst excision and curettage of the tibial tunnel with full recovery and return to preinjury level of activity 2 months after the revision surgery. To our knowledge, the reported complication is the first obvious adverse reaction to a poly-D,L-lactide interference screw in anterior cruciate ligament surgery.     

Arthroscopic tenodesis using a bioabsorbable interference screw and soft anchor: A case series of 60 patients

BackgroundVarious arthroscopic tenodesis techniques for the treatment of long head of the biceps tendon pathologic abnormalities have been described.PurposeThis study evaluated the clinical outcomes of using a bioabsorbable interference screw and soft anchor for long head of the biceps tendon arthroscopic tenodesis.MethodsSixty patients treated by this technique between February 2013 and March 2015 were followed up for at least 2 years. In our operative technique, after the bone hole was made just proximal to the pectoralis major, the soft anchor was inserted at the bottom of the hole. After tenotomy of the long head of the biceps tendon proximal to the bone hole, the tendon was fixed into the bottom of the hole temporarily using the soft anchor. Finally, the tendon was fixed in the hole with a bioabsorbable interference screw.ResultsThe UCLA score 15.1 points preoperatively and 32.4 points at follow-up (p < 0.05). The Constant 55.8 points preoperatively and 93.9 points at follow-up (p < 0.01). After biceps tenodesis, no cosmetic deformities were found in 56 patients (93.3%), and four patients (6.7%) had a Popeye deformity. On postoperative magnetic resonance evaluation, the long head of the biceps tendon was located on the bicipital groove without deviation in 53 cases (88.3%), on the bicipital groove with a partial deviation in 6 cases (10.0%), and outside the bicipital groove with complete deviation (dislocated) in 1 case (1.7%).ConclusionWe found that arthroscopic biceps tenodesis using a soft anchor provided a reliable means for treating biceps pathology with no cosmetic deformities and with good clinical results.     

关节镜下可吸收交叉钉固定腘绳肌腱重建前十字韧带

目的介绍在关节镜下腘绳肌腱移植重建前十字韧带并利用可吸收交叉钉固定的方法，探讨其临床效果。方法2005年3月至2006年3月，共治疗31例前十字韧带断裂患者。男18例，女13例；年龄19-51岁，平均34岁。致伤原因：交通伤15例，日常生活及运动损伤16例。病程为5d～36个月。合并半月板损伤12例，合并内侧副韧带Ⅰ、Ⅱ度损伤6例，Ⅲ度损伤3例，均为新鲜损伤。合并后十字韧带断裂6例。术后随访12-24个月，平均16．8个月，观察此固定方法的可靠性和疗效。以Lyscholm评分和KT-2000评价手术前后膝关节功能及稳定性。结果26例患者获得随访，所有患者均无伸膝受限，膝关节屈曲活动度均〉120°。屈膝90°时前抽屉试验均阴性；Lachman试验强阳性1例，阳性4例，阴性21例；膝关节功能Lyscholm评分为（94．6±4．2）分。KT-2000检查结果：25例双膝差距为0-4．0mm，平均2．4mm，1例患者关节不稳定，双膝差距5．5mm。结论可吸收交叉钉固定可为关节镜下腘绳肌腱移植重建前十字韧带提供早期的初始稳定性和后期的生物稳定性，是一种可靠的固定方法。     

ACL reconstruction by bone-patellar tendon-bone graft: mechanical evaluation of the elastic modulus and failure modes

The aim of this study was to apply an engineering approach to study the biomechanical behaviour of both native and reconstructed anterior cruciate ligaments (ACL) under tensile test, simulating the primary stability of the reconstructed ACL in the immediate postoperative period, when the bone callus has not formed yet. We used the bovine bone-patellar tendon-bone grafts to reconstruct ACL in bovine knees. The grafts were fixed by means of titanium interference screws and titanium transverse compressive screws. We tested 18 native and 18 reconstructed ligaments (7 with interference screws and 11 with transverse compressive screws). We applied mechanical tension at a 500 mm/min strain rate, and observed the mode of failure. The data analysis confirmed the different behaviour recorded in load elongation curves, a difference enhanced in stress-strain curves for both fixation methods. The stress-strain patterns for the interference screw and for the native ligament were quite similar.     

前交叉韧带重建胫骨栓桩与挤压螺钉固定的比较

[目的]评估膝关节前交叉韧带损伤胫骨栓桩固定及可吸收挤压钉固定的疗效。[方法] 2011～2016年治疗膝关节前交叉韧带损伤患者61例,股骨骨道均以Endobutton固定,其中胫骨骨道栓桩固定25例,胫骨骨道可吸收挤压钉固定36例,手术前后行Lachman试验、IKDC和Lysholm评分,以评估手术疗效。[结果] 61例患者均顺利接受手术,术中无血管神经损伤等严重并发症。术后栓桩组平均随访(13.62±1.23)个月,挤压钉组随访(14.72±1.16)个月。末次随访时栓柱钉组25例患者和挤压钉组36例患者均无明显疼痛、交锁和打软腿症状,前抽屉试验、轴移试验及Lachman试验均为阴性。两组的ROM均随时间延长有所增加,但差异无统计学意义(P0.05),不同时间点两组间ROM的差异均无统计学意义(P0.05)。术后6、12个月时两组的KT-1000值均较术前显著减少,差异有统计学意义(P0.05),而两组术后6个月与12个月的KT-1000值差异均无统计学意义(P0.05)。相同时间点两组间KT-1000值的差异均无统计学意义(P0.05)。随着时间延长,两组患者的Lysholm评分和IKDC 2000评分均显著增加,两组患者不同时间点的差异均有统计学意义(P0.05),但相同时间点两组间Lysholm评分和IKDC2000评分的差异均无统计学意义(P0.05)。[结论]前交叉韧带重建胫骨骨道可吸收挤压螺钉固定与皮质骨螺钉栓桩固定术后均取得较好疗效,两组相比较无明显差别,胫骨侧栓桩固定也是一种可靠的固定方法。