Tendon healing in a bone tunnel. Part II: Histologic analysis after biodegradable interference fit fixation in a model of anterior cruciate ligament reconstruction in sheep

Purpose: Tendon-to-bone healing of soft-tissue grafts has been described to progress by the development of a fibrous interzone that undergoes a maturation process leading to the development of an indirect type of ligament insertion. Previous studies used extra-articular models or fixation far away from the joint line; thus, no data are available investigating tendon-to-bone healing of a soft-tissue graft fixed anatomically. Therefore, we studied the tendon-to-bone healing of the anatomic soft-tissue graft interference fit fixation in a model of anterior cruciate ligament (ACL) reconstruction in sheep. Type of Study: Animal study. Methods: Thirty-five mature sheep underwent ACL reconstruction with an autologous Achilles tendon split graft. Grafts were directly fixed with biodegradable poly-(D,L-lactide) interference screws. Animals were euthanized after 6, 9, 12, 24, and 52 weeks and histologic evaluations were performed. Undecalcified specimens were evaluated under normal and polarized light. Additionally, animals received a polychrome sequential labeling (tetracycline, xylenol orange, and calcein green) to determine bone growth per time under fluorescent light. Results: Intratunnel histologic findings at 6 weeks showed a tendon-bone junction with only a partial fibrous interzone between the graft tissue and the surrounding bone. A mature intratunnel tendon-bone junction with a zone of fibrocartilage was found at 9 to 12 weeks. At the tunnel entrance site a wide regular ligamentous insertion site was seen in all specimens after 24 weeks. This insertion showed regular patterns such as the direct type of insertion of a normal ligament with a dense basophilic transition zone consisting of mineralized cartilage. Conclusions: A fibrous interzone between the graft tissue and the bone tunnel was only partially developed, which is in contrast to all previous studies in which nonanatomic fixation was used. Thus, it is reasonable to assume that the tendon-to-bone healing in the present study may progress partially by direct-contact healing without the development of a fibrous interzone. To our knowledge, this is the first report describing the development of a direct type of ligament insertion after ACL replacement with a soft-tissue graft. This is in contrast to previous studies reporting the development of an indirect type of insertion when using nonanatomic fixation far away from the joint line. Thus, histologic data strongly indicate that anatomic interference fit fixation is beneficial for tendon-to-bone incorporation by leading to the development of a direct type of ligament insertion.Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 18, No 2 (February), 2002: pp 124–135     

Graft healing in the bone tunnel in anterior cruciate ligament reconstruction

The histologic sequence in the bone tunnel after anterior cruciate ligament reconstruction using the bone-patellar tendon-bone graft was investigated in this study. Eighteen adult mongrel dogs were used. After excision of the anterior cruciate ligament, the graft was routed through the bone tunnels and fixed with interference fit screws. After the dogs were sacrificed at intervals, the bone blocks containing the bone tunnels were isolated and processed for histologic examination. At the bone-bone interface, incorporation of the bone plug at each end of the graft was completed at 12 weeks. The structure of the tendon insertion of the grafted patellar tendon, consisting of four distinct zones, was observed without apparent necrotic and degenerative change for as long as 12 weeks. Between the tendon and the bone tunnel, a layer of hypercellular fibrous tissue gradually became mature with time. Thus, it appeared the morphologic characteristics and location of the reestablished attachment of the bone-patellar tendon-bone graft were more similar to those of the native anterior cruciate ligament compared with the graft to bone healing in the hamstring tendon graft.     

All-inside anterior cruciate ligament reconstruction using semitendinosus tendon and soft threaded biodegradable interference screw fixation

A modification of anterior cruciate ligament (ACL) reconstruction using a minimally invasive and endoscopic all-inside technique is presented. Both the femoral and tibial socket are approached through the joint so that there is no open tibial tunnel, which otherwise often causes significant pain and discomfort during early rehabilitation. The autologous semitendinosus tendon is harvested with a bone plug attached to its tibial insertion. The triple-stranded semitendinosus tendon is looped around the adjacent bone plug and fixed at the original tibial attachment site of the ACL using a soft threaded biodegradable poly-(D,L-lactide) interference screw. The screw is inserted endoscopically in an inside-out direction. In the femoral socket the graft is fixed without a bone plug directly to the tunnel wall using the biodegradable screw. The free part of the graft is thus not longer than the intra-articular distance, which may increase stiffness of the construct.     

Biomechanical comparison of quadriceps tendon fixation with patellar tendon bone plug interference fixation in cruciate ligament reconstruction

Purpose: The purpose of this study was to use current fixation techniques and compare the stiffness and ultimate tensile failure of the tendinous end of the quadriceps tendon (QT) with the bone plug end of the bone–patellar tendon–bone (BPTB) graft using current techniques of fixation. Type of Study: Randomized trial of elderly cadaver knees. Materials and Methods: Tibial and femoral biodegradable interference fixation and femoral EndoButton (Smith & Nephew, Acufex, Mansfield, MA) fixation in bone tunnels with the QT and the BPTB graft were compared by using 10 pairs of elderly cadavers and biomechanical testing. Two groups, fixation at time zero (simulating fixation in the operating room) and testing after 1,000 loading cycles (simulating patient rehabilitation exercises), were used. Results: At time zero fixation, stiffness of the soft tissue QT tibial tunnel interference fixation was 59% less stiff than the stiffness of the interference fixation of a BPTB plug in a femoral tunnel (P = .11). The EndoButton femoral fixation resulted in a decrease in stiffness at time zero compared with femoral tunnel interference fixation of the soft tissue QT (P = .03). All groups improved stiffness with cycling the construct to 1,000 cycles. Conclusions: Placement of the QT tendinous end of the graft in the femoral bone tunnel when using a interference fixation will approximate the stiffness of a bone plug in the tibial bone tunnel with interference fixation. The EndoButton fixation is not as stiff as either of the femoral interference fixation options. The addition of more than 20 loading cycles could remove laxity from the graft fixation–graft cruciate ligament complex and improve its stiffness.     

Bioabsorbable interference screws for graft fixation in anterior cruciate ligament reconstruction.

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 = 103) or the metal interference screw (n = 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 = 1.8mm and M = 1.6mm. The Tegner activity level score means were B = 6.1 and M = 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.     

Influence of bone adaptation on tendon‐to‐bone healing in bone tunnel after anterior cruciate ligament reconstruction in a rabbit model

Anterior cruciate ligament (ACL) reconstruction with placement of grafted tendon in bone tunnel is a common surgical procedure. Bone tunnel creation may result in stress shielding of postero‐lateral regions of tibial tunnel. The present study was designed to characterize the changes of peri‐graft bone and compare with tendon‐to‐bone (T‐B) healing in spatial and temporal manners after ACL reconstruction in rabbit. Surgical reconstruction using digital extensor tendon in bone tunnel was performed on 48 rabbits. Twelve rabbits were sacrificed at 0, 2, 6, and 12 weeks postoperatively for radiological and histological examinations. Bone mass and microarchitecture at the anterior, posterior, medial, and lateral regions of tunnel wall at distal femur and proximal tibia were evaluated. Using peripheral quantitative computed tomography, a 26, 22, and 42% decrease in bone mineral density (BMD) relative to baseline was present in the medial region of the femoral tunnel and the posterior and lateral regions of the tibial tunnel, respectively, at week 12 postoperatively (p < 0.05). It was accompanied by a decrease in trabecular number and increase in trabecular spacing, the shift of platelike to rodlike trabeculae, and loss of anisotropy under micro‐computed tomography evaluation. This finding was echoed by histology showing increased osteoclastic activities and poor T‐B healing in these regions. In conclusion, the postoperative bone loss and associated poor T‐B healing was region‐dependent, which may result from adaptive changes after tunnel creation. © 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 27:1447–1456, 2009     

The biomechanics of biodegradable versus titanium interference screw fixation for anterior cruciate ligament augmentation and reconstruction

Purpose

The ligament augmentation and reconstruction system (LARS) is one of the options available for anterior cruciate ligament (ACL) reconstruction. To date, however, there are no published data regarding the biomechanical properties of LARS fixation for ACL reconstruction. The aim of this study was to investigate the biomechanical properties of various LARS interference-screw fixations.

Methods

A total of 100 LARS ligaments were fixed in porcine femurs with five different interference screws (four biodegradable screws and one titanium interference screw) introduced from inside-out or extra-articularly outside-in. Each group consisted of ten specimens. The constructs were cyclically stretched and subsequently loaded until failure. We evaluated the maximum load before failure, elongation during cyclic loading, stiffness, and failure mode.

Results

Elongation during cyclical loading for all devices tested was significantly larger between the first and 20th cycles than between the 20th and 500th cycles (p?p?>?0.05). All specimens failed because of ligament pull-out from the bony tunnel.

Conclusions

Our findings suggest that biomechanical secure fixation of the LARS for ACL reconstruction can be achieved using either biodegradable or titanium interference screws. The stability of fixation is independent of the approach, type of investigation, and type of fixation (extra-articular outside-in or intra-articular inside-out).     

Biomechanical testing of implant free wedge shaped bone block fixation for bone patellar tendon bone anterior cruciate ligament reconstruction in a bovine model

Background  

The use of an interference fit wedged bone plug to provide fixation in the tibial tunnel when using bone-patellar tendon-bone autograft for anterior cruciate ligament reconstruction offers many theoretic advantages including the potential to offer a more economical and biological alternative to screw fixation. This technique has not been subjected to biomechanical testing. We hypothesised that a wedged bone plug fixation technique provides equivalent tensile load to failure as titanium interference screw fixation.     

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。     

Tripled semitendinosus-cancellous bone anterior cruciate ligament reconstruction with bioscrew fixation.

A prospective evaluation of a tripled semitendinosus-autologous cancellous bone plug ACL reconstruction, secured with bioabsorbable interference screws (Bioscrew; Linvatec, Largo, FL) made of polyL-lactic acid, was undertaken from July 1994 through August 1995. A total of 21 patients with 22 anterior cruciate ligament (ACL) reconstructions were followed-up an average 29 months (range, 20 to 45). The average age was 38 years (range, 24 to 48 years). Tegner and Lysholm scores were 2.1 and 46, respectively, preoperatively and increased postoperatively to 4.4 and 90. KT tests at 24 months follow-up showed an average 20-lb laxity of 1.4 mm, an average 30-lb laxity of 2.1 mm, and an average KT maximum manual side-to-side difference of 2.9 mm. A pivot shift was absent in all but two patients at final follow-up. Full extension was rapidly achieved in all cases and flexion averaged 135 degrees at follow-up. No problems with the poly L-lactic acid interference screws occurred. These data support the effectiveness of Bioscrew fixation of the tripled semitendinosus-cancellous bone graft ACL reconstruction, which achieves both anatomic graft position and anatomic graft fixation.     

Arthroscopic anterior cruciate ligament reconstruction using a hamstring graft with interference screw fixation.

BACKGROUND AND AIMS: This study assessed the clinical and radiographic results 3 to 8 years after an arthroscopic ACL reconstruction using a hamstring graft with interference screw fixation on femoral and tibial sites. MATERIAL AND METHODS: Seventy-six of 100 patients, who underwent an arthroscopic ACL reconstruction, could be re-examined with a mean follow-up of 5 years. RESULTS: The mean Tegner activity score was 4 (scale: 0 to 10) before surgery, and 5 at the follow-up. Fifty-four patients (78%) achieved a satisfactory result in the IKDC rating. The mean Lysholm score was 85 (scale: 0 to 100), the score being better in patients without meniscal resection than those with (P = 0.04). The mean side-to-side difference in anterior-posterior knee laxity was 1.8 mm, and 62 patients (90%) had good stability. Sixty-four patients (93%) had normal range of motion of the knee. Twelve patients (46%) with meniscal resection had osteoarthritic changes, compared with only 8 of those (20%) without meniscal resection (P = 0.03). CONCLUSIONS: This medium-term follow-up study showed that good stability and function and normal range of motion of the knee can be achieved in majority of the patients who have undergone an ACL reconstruction with a hamstring graft and interference screw fixation.     

单束单隧道与双束双隧道重建膝前交叉韧带的生物力学对比研究

[目的]研究双束股骨双隧道法重建前交叉韧带(ACL)恢复膝关节前后方向稳定性的能力,并与单束单隧道重建法进行生物力学性能的比较。[方法]应用跟腱分别采用双束股骨双隧道、单前内侧束和单后外侧束三种方法对10个新鲜尸体膝关节进行前交叉韧带重建。术后分别于膝关节屈曲0°、15°、30°、60°及90°时对胫骨施行±100 N的作用力,测量胫骨相对于股骨移动的距离。[结果]在屈膝角度较小(0°~30°)的情况下,单前内侧束重建法术后胫骨的移动距离与完整标本接近(P>0.05);但屈曲超过30°,特别是超过60°后,单前内侧束重建法术后胫骨移动的距离明显大于完整标本(P<0.05)。在屈膝角度<60°的情况下,单后外侧束重建法胫骨移动的距离明显大于完整标本(P<0.05):但屈曲超过60°胫骨移动的距离与完整标本接近(P>0.05);在膝关节的整个屈曲范围(0°~90°)内,双束股骨双隧道重建法术后胫骨移动的距离与完整标本接近(P>0.05)。[结论]双束股骨双隧道重建法,在膝关节的整个屈曲范围(0°~90°)内,比单束股骨单隧道重建法能更有效的恢复膝关节的稳定性。     

应用重组合异种骨促进前交叉韧带重建术后腱-骨愈合的研究

[目的]通过影像学、组织学及生物力学手段探讨重组合异种骨(RBX)对前交叉韧带重建术后腱-骨愈合的影响.[方法]25只新西兰白兔,利用双侧趾长伸肌肌腱重建前交叉韧带(ACL),其中一侧移植物两端固定有RBX,另一侧作为对照组,分别于术后2、6、12周取材,进行Micro-CT扫描,组织学染色(包括HE、甲苯胺蓝)以及生物力学检测,观察腱-骨之间愈合状况.[结果]影像学结果显示,术后6、12周RBX治疗组腱-骨之间的骨矿化组织密度(BMD)数值均高于对照组,并具有显著性差异;组织学结果显示,术后2周,RBX组腱-骨之间被大面积不规则分布的软骨样细胞填充;术后6周,治疗组的腱-骨之间已见大量成熟软骨细胞,并开始分泌基质.而对照组术后腱-骨间一直被纤维样结缔组织连接,至术后12周,治疗组部分标本出现类ACL正常肌腱止点.生物力学结果同样证实,RBX组的最大牵拉力均显著高于对照组.[结论]RBX可显著提高ACL重建术后腱-骨之间的愈合,较早恢复膝关节功能.     

LARS人工韧带重建前交叉韧带术后骨隧道变化特点的研究

目的 探讨LARS人工韧带重建前交叉韧带(ACL)术后骨隧道的变化特点及可能的影响因素.方法 2004年8月至2007年4月应用LARS人工韧带重建43例单纯ACL损伤患者,男31例,女12例;左膝19例,右膝24例;年龄17～48岁,平均27.5岁.于术后l、3、6、12、24、36个月分别行膝关节X线片和CT检查,记录各个时间点胫骨和股骨骨隧道的宽度.骨隧道增宽采用Peyrache等提出的分级方法进行评定.末次随访时根据Lysholm评分标准评定膝关节功能,应用KT-1000TM测量膝关节的松弛度. 结果 43例患者术后获36 ～49个月(平均39.5个月)随访.末次随访时仅3例患者出现骨隧道l级增宽,均为术后6个月发生于股骨隧道近关节面水平,平均增宽(2.5 ±0.3) mm.无一例患者出现2级和3级骨隧道增宽.不同时间点股骨、胫骨骨隧道宽度比较差异均无统计学意义(P＞0.05).X线片与CT测量结果基本一致,二者比较差异均无统计学意义(P＞0.05).末次随访时3例骨隧道l级增宽患者Lysholm评分平均为(94.5±4.6)分,KT-1000TM前移差值平均为(1.5±1.1)mm;40例0级增宽患者Lysholm评分平均为(95.6±4.8)分,KT-1000TM前移差值平均为(1.4±1.5)mm.结论 LARS人工韧带重建ACL术后骨隧道增宽并不显著,这种变化特点可能与LARS人工韧带移植物的特性及固定方法不同有关.     

前交叉韧带重建术后骨道增宽的临床研究

目的分析前交叉韧带（ACL）重建术后骨道增宽的发生率、增宽程度、骨道形状、相关因素及其与临床效果的关系。方法回顾性研究应用胭绳肌腱重建ACL手术后骨道的变化,通过X线片测量ACL重建术后的骨道直径。对51例患者行ACL重建手术,其中男性30例,女性21例。所有患者均获随访,平均随访时间16个月。主要研究及观察指标：患者性别、年龄、身高等因素,移植物的固定方式,随访时的关节活动度、膝关节稳定性检查（KT2000）及肌力恢复情况,以及股骨和胫骨的骨道直径、骨道位置和角度等。数据分析采用统计学卡方检验及相关性分析。结果前交叉韧带重建术后的骨道增宽率股骨85％-94％,胫骨65％;增宽程度股骨51％-53％,胫骨40％～44％。胫骨骨道增宽的形态以O型（冠位片）及V型（矢位片）最常见。骨道增宽与年龄、身高及体重指数相关。股骨骨道位置偏前会引起股骨骨道的增宽,股骨骨道角或胫骨骨道角越小,则股骨骨道越容易增宽。结论以腘绳肌腱为移植物重建前交叉韧带手术,术后骨道增宽的发生率与程度,股骨骨道较胫骨骨道明显。骨道增宽与患者年龄、身高以及骨道定位相关,其中股骨和胫骨骨道的位置及角度是引起术后骨道增宽的主要因素之一。骨道增宽与KT2000结果和术后肌力恢复情况相关。     

生物骨传导性骨水泥促进前交叉韧带重建术腱骨愈合的研究进展(英文)

近10年来,应用软组织移植物行前交叉韧带重建术越来越普遍。手术的远期疗效主要取决于肌腱移植物能否在骨隧道内达到坚强的腱-骨愈合。但是,目前面临的问题是肌腱移植物在骨隧道内获得腱-骨愈合所需要的时间相当长。研究发现,在腱-骨界面局部应用生物骨传导性的骨水泥能有效地促进肌腱移植物的骨愈合。这类骨水泥主要是磷酸钙。本文就生物骨传导性骨水泥促进前交叉韧带重建术腱-骨愈合的研究进展作一综述。     

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.