Patellar tendon augmentation after removal of its central third limits joints tissue changes.

The central third of the patellar tendon is commonly used to reconstruct the injured anterior cruciate ligament. Some studies have noted changes in joint tissues following this procedure. It has been postulated that these changes may be associated with increased stress on the remaining tendon following harvest of the graft. In our study, the central third of the patellar tendon was excised in three groups of rabbits. The central tendon defects in two of the three groups were fitted with different augmentation devices to augment the host tendon during the healing process. All rabbits followed a daily treadmill exercise regimen for 12 weeks following the operation. Biomechanical testing of the tendon revealed that in nonaugmented tendons the cross-sectional area and the length of the patellar tendon significantly increased 112 and 16%, respectively. There was histological evidence of host-tendon remodeling throughout the cross section and extensive fibrosis in the infrapatellar fat pad. Augmentation of the tendon significantly reduced these changes, with the least change noted in the group with the greatest augmentation. The rabbits with augmentation devices retained tendon dimensions similar to those of the contralateral intact tendon, and tendon remodeling occurred only in the defect area. The rabbits with augmentation devices exhibited little to no fibrosis of the fat pad. Structural properties of augmented and nonaugmented tendons were similar despite the size differences, indicating higher tissue quality in the augmented tendons. This study suggested that complications of the knee joint (i.e., tendon proliferation and fat pad fibrosis) noted after anterior cruciate-ligament reconstruction with the autogenous patellar tendon may be limited by the implantation of an augmentation device.     

Dacron augmentation in anterior cruciate ligament reconstruction in dogs

Substitution of the central third of the patellar tendon for the deficient anterior cruciate ligament was performed in 12 dogs (24 knees). In one-half of the knees the patellar tendon grafts were "augmented" with a 4-mm woven Dacron graft. It was hypothesized that Dacron augmentation would protect the patellar tendon graft during its revascularization stages. This was not the case, however. Only once did a Dacron ligament graft demonstrate superiority over the nonaugmented graft; indeed, five of the augmented grafts performed significantly worse.     

Nerve regeneration during patellar tendon autograft remodelling after anterior cruciate ligament reconstruction: An experimental and clinical study

The innervation of the rat and human anterior cruciate ligament, patellar tendon, and patellar tendon autograft after reconstruction of the anterior cruciate ligament was investigated by immunohistochemical and histological methods. A rat model of reconstruction with patellar tendon autograft was evaluated during active graft remodelling (2–16 weeks) and compared with normal ligament and tendon. The knees of 10 patients who had undergone reconstruction with patellar tendon autograft were examined 5–37 months postoperatively (remodelling fully completed) with arthroscopy and biopsy. As a control, biopsies from normal ligament and tendon were obtained from four patients. Nerve fibers were identified using antisera for protein gene product 9.5, a general neural marker. Neuronal regeneration was assessed by the expression of growth-associated protein 43/B-50. The sensory type of innervation was characterized by assessing the distribution of nerves containing the sensory neuropeptides calcitonin gene related peptide and substance P. Immunoreactivity for all neural markers was found in both rat and human anterior cruciate ligament and patellar tendon. Two weeks after reconstruction, the rat autograft was acellular and no innervation could be identified. After 4 weeks, the grafts were viable, and immunoreactivity for protein gene product 9.5, growth associated protein 43/B-50, and calcitonin gene-related peptide was found until the 16th week postoperatively. Immunoreactivity for substance P was found in rat autografts at 4 weeks postoperatively only. All biopsies of human patellar tendon autograft showed signs of the remodelling process being fully completed, with revascularization and a sinusoidal collagen pattern with fibroblast repopulation. Neuropeptide immunoreactivity, however, was not found. The presence of immunoreactivity to sensory neuropeptides in the anterior cruciate ligament and patellar tendon may indicate a nociceptive and neuromodulatory function of these structures. The expression of sensory neuropeptides in the rat patellar tendon autograft suggests a possible involvement of sensory innervation during healing of the graft.     

Evaluation of bone incorporation of patellar tendon autografts and allografts for ACL reconstruction using CT

Anterior cruciate ligament (ACL) reconstruction is a relatively common orthopedic procedure, with patellar tendon frequently a graft source. However, controversy exists regarding the decision to use autograft or allograft patellar tendon tissue. This experimental study used computed tomography (CT) to compare the percentage of bone graft incorporation following ACL reconstruction using autografts and allografts. Fifty consecutive patients undergoing ACL reconstruction were included in the study. The tibial bone plug was imaged with CT 1 week, 2 months, and 5 months postoperatively. Four images from each completed scan were analyzed for percentage of incorporation of the bone graft. The results of autograft and allograft incorporation for each of the time intervals were compared. No statistically significant difference was found in the amount of bone incorporation at the tibial bone plug 1 week, 2 months, and 5 months. Clinical concerns regarding slower or less complete healing of allograft bone tissue compared to autograft are not supported with regard to the grafts studied.     

Healing phases in autogenous posterior cruciate ligament replacement. A decision aid for after-care. A biomechanical and histologic study

In a sheep model for reconstruction of the posterior cruciate ligament using the central one-third of the autogenous patellar tendon and immediate mobilization, the incorporation course was studied biomechanically, histomorphometrically and radiographically at eight different points in time up to 1 year after surgery. Four different phases of autograft healing were demonstrated on the basis of the histological events. The biomechanical data were correlated with the morphological findings. Phase 1--necrosis--was characterized by a maximum of necrotic autograft tissue 2 weeks postoperatively. Initially, graft strength was determined by the surgical fixation strength. During phase 2--revitalization--the autograft showed cellular proliferation and revascularization, starting from the periphery. The autograft was determined to be weakest during this phase. Phase 3--collagen formation--revealed a marked increase in newly formed collagen tissue between weeks 12 and 16. A significant increase in maximum load and stress was measured. In phase 4--remodeling--the longest phase, the collagen tissue appeared more compact and less cellular. The fiber bundles were arranged more longitudinally. However, the biomechanical properties remained clearly below that of a normal posterior cruciate ligament.     

Distribution of cellular repopulation and collagen synthesis in a canine anterior cruciate ligament autograft

Whether the central core of an anterior cruciate ligament autograft reconstruction is nutritionally compromised at a time when revascularization is known to be complete has not been determined by methods that detect matrix synthesis. In a canine model of anterior cruciate ligament reconstruction with patellar tendon autograft, the adequacy of the supply of metabolites for cellular matrix synthesis was determined by autoradiographic analysis. Total collagen synthesis and cellularity were also quantified. Total collagen synthesis was found to be significantly elevated (p = 0.014 by analysis of variance) in the ligament reconstructions as compared with normal anterior cruciate ligaments or patellar tendons, but cellularity was not (p = 0.13 by analysis of variance). Autoradiography demonstrated even distribution of [³H]proline incorporation throughout the graft and normal tissue. When revascularization was complete, there was an adequate supply of metabolites for cellular synthesis of protein macromolecules within all regions of the ligament reconstruction. At 3 months after reconstruction, the grafts were found to be actively remodeling their collagen matrix. Since the long-term function of an anterior cruciate ligament autograft is dependent on viable fibroblasts to maintain the collagen matrix, the canine anterior cruciate ligament reconstruction contains living cells that are able to remodel the matrix under appropriate conditions.     

Origin of replacement cells for the anterior cruciate ligament autograft

A rabbit model for anterior cruciate ligament (ACL) reconstruction using autogenous avascular patellar tendon (PT) was utilized to study the early events of graft incorporation. Histological observations demonstrated that autografts were centrally acellular with a peripheral rim of cells at 2 weeks, a central focal proliferation of cells at 3 weeks, and a cellular homogeneous distribution by 4-weeks postoperation. Graft necrosis followed by cellular proliferation suggested that a different population of cells other than the native PT fibroblasts may be inhabiting the graft. The extrinsic contribution of cells was studied by selective destruction of native PT cells with liquid nitrogen immersion prior to reconstruction of the ACL. The intrinsic contribution of cells was evaluated by sequestration of the PT graft in a semipermeable membrane before it was used to reconstruct the ACL. Histological analysis of tissue that was liquid N2 treated, used as an autograft, and then harvested 3-weeks postoperation revealed fibroblastic incorporation of the graft. In contrast, no cells were observed in semipermeable membrane sequestered autografts. These data suggest that autogenous ACL autografts of PT origin are repopulated by cells of external origin. In vitro control studies that were carried out in parallel demonstrated that PT fibroblasts could survive in tissue culture, but not in the synovial environment of the ACL. This suggests that fibroblasts from different sources have different, tissue-specific nutritional requirements.     

Posterior Cruciate Ligament Reconstruction Using Hamstring Tendon Graft With Remnant Augmentation

Despite good early functional results, the posterior laxity of the knee is not completely eliminated after posterior cruciate ligament (PCL) reconstruction. The PCL can retain the normal tension only when the injured ligament is maintained anatomically. This article describes a technique of PCL reconstruction using hamstring tendon graft with PCL remnant augmentation. The harvested hamstring tendons were quadrupled, sized, and pretensioned before use. The PCL remnants and the synovium were preserved. Minimal debridement was performed to gain access to the insertion sites. The tibia and femoral tunnels were created with graft size–matched reamers. The graft was transfixed at 70° of knee flexion with a 15-lb anterior drawer force on the proximal tibia. This surgical technique has several advantages. The hamstring graft acts as an independent PCL reconstruction and maintains the PCL remnant tension. The PCL remnants and synovium may be beneficial to ligament healing and postoperative rehabilitation. The procedure is technically feasible and cosmetically acceptable. The selection of autograft precludes the risks of allograft and artificial ligament. The short-term results are encouraging, but long-term results are needed to confirm the value of this technique for PCL reconstruction.     

The ligament augmentation device: an historical perspective.

Anterior cruciate ligament (ACL) injury is the most common ligament injury in the knee, and a significant number of patients may develop progressive instability and disability despite aggressive rehabilitation. Various materials have been used for its reconstruction. These include autografts, allografts, prosthetic ligaments, and synthetic augmentation of the biological tissue. The concept of ligament augmentation device (LAD) arose from the observation that biological grafts undergo a phase of degeneration and loss of strength before being incorporated. The LAD is meant to protect the biological graft during this vulnerable phase. However, it provokes an inflammatory reaction in the knee, and has been found to delay maturation of autogenous graft in humans. In experimental situations, the LAD has been found to share loads in a composite graft. It has also been found to be substantially stronger than the biological graft. However, in clinical situations no significant advantages have been observed with the use of LAD to augment patellar tendon or hamstring reconstruction of the chronic ACL-deficient knee or in the acute setting to augment repair of the torn ACL. There are very few reports of the use of LAD in reconstruction of the posterior cruciate ligament, and again these do not suggest any advantage in its use. Insertion of the LAD implies the introduction of a foreign material into the knee, has been associated with complications such as reactive synovitis and effusions, and may also be associated with an increased risk of infection. At present, there is no evidence that its routine use should be advocated in uncomplicated reconstructions of the ACL using biological grafts.     

Hamstring tendon autograft versus LARS artificial ligament for arthroscopic posterior cruciate ligament reconstruction in a long-term follow-up

Introduction

Surgical reconstruction has been increasingly recommended for the surgical management of posterior cruciate ligament (PCL) ruptures. While the choice of tissue graft still remains controversial. Currently both hamstring tendon autograft (HTG) and ligament advanced reinforcement system (LARS) artificial ligament are widely used but there are seldom reports on the comparisons of their clinical results. Our study was aimed to assess the effectiveness of these two grafts.

Materials and methods

Thirty-five patients with unilateral PCL rupture were enrolled in this retrospectively study. Sixteen of them received arthroscopically assisted PCL reconstruction using hamstring tendon autografts (HTG group) and nineteen using LARS ligaments (LARS group). All cases were followed up for 46–57 months with a mean of 51 months. Follow-up examinations included radiographic assessment, Lysholm score, Tegner score, International Knee Documentation Committee (IKDC) rating scales and KT-1000 test.

Results

All patients improved significantly at the final follow-up compared with the examinational results preoperatively and there were no significant differences between HTG group and LARS group with respect to the results of radiographic assessment, Lysholm score, Tegner score, IKDC rating scales and KT-1000 test.

Conclusions

Similar good clinical results were obtained after PCL reconstruction using hamstring tendon autografts and LARS ligaments. Both LARS ligament and hamstring tendon autograft are ideal grafts for PCL reconstruction.     

Graft selection in anterior cruciate ligament reconstruction

The ideal graft for use in anterior cruciate ligament reconstruction should have structural and biomechanical properties similar to those of the native ligament, permit secure fixation and rapid biologic incorporation, and limit donor site morbidity. Many options have been clinically successful, but the ideal graft remains controversial. Graft choice depends on surgeon experience and preference, tissue availability, patient activity level, comorbidities, prior surgery, and patient preference. Patellar tendon autograft, the most widely used graft source, appears to be associated with an increased incidence of anterior knee pain compared with hamstring autograft. Use of hamstring autograft is increasing. Quadriceps tendon autograft is less popular but has shown excellent clinical results with low morbidity. Improved sterilization techniques have led to increased safety and availability of allograft, although allografts have a slower rate of incorporation than do most types of autograft. No graft has clearly been shown to provide a faster return to play. However, in general, patellar tendon autografts are preferable for high-performance athletes, and hamstring autografts and allografts have some relative advantages for lower-demand individuals. No current indications exist for synthetic ligaments.     

Editorial Commentary: Reduce the Failure Risk: A Challenge to Reduce the Risk of Using Hybrid Graft in Anterior Cruciate Ligament Reconstruction

Hybrid grafting (augmentation of small hamstring autografts with allograft tissue) is preferred by many surgeons for anterior cruciate ligament (ACL) reconstruction. Although a recent, well-conducted, systematic review reported no significant differences in failure risk between hybrid graft and autograft ACL reconstruction, a trend toward a greater failure risk using the hybrid graft existed in many of the included studies. Three potential causes of hybrid graft ACL reconstruction failure that are absent in autograft ACL reconstruction are different levels of graft revascularization and ligamentization, differences in the tendon-bone healing capacity between the allograft and autograft portions in the bone tunnel, and processing of the graft. Research advances in these areas will further reduce the failure risk of hybrid graft ACL reconstruction.     

自体骨-髌腱-骨移植重建膝后交叉韧带

目的 介绍以自体骨－髌腱－骨重建膝关节后交叉韧带的方法并评价其对治疗膝关节后不稳定的临床效果。方法 采用膝前方入路,经胫骨－肌骨等长点骨隧道植入自体髋腱重建后交叉韧带（ＰＣＬ）,治疗陈旧性ＰＣＬ断裂所致慢性膝关节不稳病例２０例。采用Ｌａｒｓｏｎ膝关节功能评分、患者主观评价和膝关节稳定性检查评价其临床疗效。结果 ２０例患者术前Ｌａｒｓｏｎ评分平均６２分,沐后经６￣５８个月随访,平均评分达９２分,１８     

Augmentation of anterior cruciate ligament reconstruction in dogs with prostheses of different stiffnesses

The purpose of this study was to investigate the biological and biomechanical properties of anterior cruciate ligament (ACL) reconstruction augmented with Dacron prostheses of three different stiffnesses. The ACLs of 36 adult mongrel dogs were removed and the ligament was reconstructed. In 18 dogs, one knee was reconstructed with patellar tendon alone, and the contralateral knee with Dacron augmented patellar tendon. In the remaining 18 dogs, reconstruction was with Dacron augmented patellar tendon with Dacron alone being used for the contralateral control knee. Death was 3 months after surgery, and the reconstructions were examined biologically and biomechanically. The mechanical data were compared with immediate postoperative data obtained from 45 reconstructed fresh cadaveric knees. Tensile testing demonstrated that an increase in failure load was found when the implanted patellar tendon graft was compared with the cadaveric reconstruction. The strength of the Dacron augmented reconstruction showed little change while the Dacron alone graft decreased in strength during the period of implantation. No clear difference was found between the performance of augmentation devices of different stiffnesses. Microangiography showed that grafts were totally revascularized in patellar tendon alone, but not well revascularized in Dacron augmented patellar tendon and Dacron alone reconstruction. The presence of the Dacron appeared to have an adverse effect on revascularization.     

自体Hamstring腱重建前交叉韧带术后关节镜下再视观察

目的关节镜再视观察游离Hamstring腱重建前交叉韧带后在体内重塑与转归过程.方法关节镜下再视手术,观察关节镜下自体同侧游离Hamstring腱重建前交叉韧带33例.重建术至再视手术时间为2～36个月,平均11.9月.依据重建术至再视术的时间,替代腱按时段分组:1月～,4月～,7月～,10月～,13月～,18月～和25月～组.再视术重点观察评估了移植的Hamstring腱形状、色泽、张力、覆盖的滑漠组织和血管状况.结果再视关节镜下重建前交叉韧带的Hamstring腱随植入时间延长,其形态逐步向正常前交叉韧带重塑与转归;7月～组和此后各组的替代腱在关节镜视下表现为.一种几乎无滑膜和血管的灰白色粗壮的圆柱体,类似于正常的前交叉韧带组织,达到了在体内成熟的程度.结论自体游离多股Hamstring腱重建前交叉韧带术后具有良好早期存活,快速再血管化和重塑过程,其术后的重塑与成熟过程与自体髌腱的过程相似,但其在体内重塑与转归进程相对较快.     

One-incision endoscopic technique for posterior cruciate ligament reconstruction with quadriceps tendon–patellar bone autograft

Quadriceps tendon–patellar bone autograft is an alternative graft choice for posterior cruciate ligament (PCL) reconstruction. A 2-incision technique with outside-in fixation at the femoral condyle is generally used. In this article, we describe a 1-incision endoscopic technique for PCL reconstruction with quadriceps tendon–patellar bone autograft. The graft consists of a proximal patellar bone plug and central quadriceps tendon. The bone plug is trapezoidal, 20 mm long, 10 mm wide, and 8 mm thick. The tendon portion is 80 mm long, 10 mm wide, and 6 mm thick, including the full-thickness of the rectus femoris and partial thickness of the vastus intermedius. Three arthroscopic portals, including anteromedial, anterolateral, and posteromedial, are used. All procedures are performed in an endoscopic manner with only 1 incision at the proximal tibia. At the femoral side, the bone plug is fixed by an interference screw. At the tibial side, the tendon portion is fixed by a suture to a screw on the anterior cortex and an interference bioscrew in the posterior tibial tunnel opening. Quadriceps tendon autograft has the advantages of being self-available, allowing for easier arthroscopic technique, and providing comparable graft size. The 1-incision technique provides a simple reconstruction method for PCL insufficiency without a second incision at the medial femoral condyle.Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 17, No 3 (March), 2001: pp 329–332     

膝关节镜下采用挤压螺钉固定骨-髌腱-骨自体移植重建前交叉韧带

目的　探讨采用关节镜下微创手术的方法重建膝关节前交叉韧带。　方法　在膝关节镜下采用挤压螺钉固定骨 髌腱 (中 1/ 3) 骨复合体自体移植重建前交叉韧带 ,术后 1年以上者 2 0例 ,平均随访时间 1年 5个月。　结果　按关节功能评定标准 ,本组 2 0例中 ,优 13例 ,良 5例 ,可 2例 ,优良率 90 % ;9例术后关节镜观察重建前交叉韧带的形态结构 ,7例塑形改建良好。　结论　关节镜下重建前交叉韧带手术创伤小 ,骨道定位准确、固定牢固 ,可做到等长重建 ,有利于早期康复 ;由于利用了自体骨 髌腱 骨组织 ,重建的韧带经塑形改建后可获得牢固的生物学固定     

Anterior cruciate ligament reconstruction with patellar autograft tendon

There are many techniques, graft choices, and outcome studies evaluating anterior cruciate ligament reconstruction. The current authors specifically look at reconstruction with the patellar tendon from a scientific perspective. Miniopen, endoscopic, and two-incision operative techniques in addition to hamstring versus patellar tendon autograft reconstructions are compared via randomized prospective studies. A review of all studies evaluating arthroscopically-assisted anterior cruciate ligament reconstruction with patellar tendon was conducted. The authors found arthroscopically-assisted anterior cruciate ligament reconstruction to have a high short-term stability rate, extremely high patient satisfaction level, and a low postoperative complication rate. When the endoscopic technique was compared with the two-incision technique, there were no major differences. The difference between patellar tendon and hamstring autograft reconstruction can be described best as subtle, except for the consistent finding of an increased activity level in the patellar tendon group. When the principles of anterior cruciate reconstruction are followed, one can expect consistent results with patellar tendon autograft reconstruction.     

Influence of immobilization on autograft healing in the knee joint

Summary The influence of immobilization on patellar tendon autograft healing was investigated in 12 sheep with replaced posterior cruciate ligaments of the knee (PCLs). In one group achillotomy immobilized the operated knee joint. In another group initial reduced weightbearing was obtained by hanging the sheep in a special trapeze. In the third group no protection at all was given to the operated knee. The sheep in this group went within 8 weeks from partial use of the operated leg to unrestricted weightbearing and mobility. Biomechanical testing 16 weeks after the operation demonstrated a considerable decrease in the maximum force, ligament stiffness, and strain values in the achillotomy group, as well as an increase in posterior laxity. The best data were observed in the no-protection group. This study demonstrates the negative effect of immobilization on autograft healing in a sheep PCL model. Even early in the healing process tissue may be extremely sensitive to stress and strain.Supported by the Deutsche Forschungsgemeinschaft (OE 88 2-1)     

Reconstruction of old anterior cruciate ligament injuries: No difference between the Kennedy LAD-method and traditional patellar tendon graft in a prospective randomized study of 40 patients with 4-year follow-up

In a prospective randomized study we investigated 40 patients with functional instability due to old anterior cruciate ligament tears by using two different techniques for reconstruction of the ligament. 20 patients were randomized to reconstruction with use of a traditional medial bone-patellar tendon graft and 20 patients to a half-thickness patellar tendon graft augmented with the Kennedy Ligament Augmentation Device (LAD). At follow-up after 4 years, both groups were still improved concerning function scores and arthrometry. The use of the Kennedy LAD method, however, gave no more subjective or objective benefits than did the traditional method.