Cruciate ligaments in arthritic knees: a histologic study with radiologic correlation

Anterior cruciate ligaments (ACLs) and posterior cruciate ligaments (PCLs) from 45 osteoarthritic knees were histologically examined to evaluate the frequency and grade the severity of degenerative changes, which were correlated with radiologic grade of arthritis and severity of deformity at the knee. Immunohistochemical staining was used to identify neurofilaments in 10 knees. A histologic score was generated for both cruciates based on changes found on light microscopy. The ACL was severely degenerated, absent, or disrupted in knees with radiologic arthritis higher than grade 3 and varus deformity exceeding 15 degrees . The PCL was moderately degenerated in most knees irrespective of the grade of arthritis and severity of deformity. Neurofilaments were present in all 10 PCLs and absent in 4 ACLs.     

Macroscopic and histological assessments of the cruciate ligaments in arthrosis of the knee

We examined the macroscopic appearance of both cruciate ligaments in 52 knees during knee replacement. It was classsified as normal, abnormal or ruptured. The ligaments were also evaluated histologically: stage 0 (normal), stage I (degeneration of < 1/3 of the collagen fibers), stage 2 (degeneration of 1/3-2/3) and stage 3 (> 2/3). 17 anterior cruciate ligaments (ACL) were normal, 14 were abnormal and 21 ruptured. All the posterior cruciate ligaments (PCL) were normal. 14 ACL were stage 0, 6 stage 1, 8 stage 2 and 24 were stage 3. 22 PCL were stage 0, 14 stage 1, 13 stage 2 and 3 were stage 3. When the ACL was abnormal or ruptured, the PCL was stage 0 only in one fourth of the cases. The long-term results of TKR retaining the PCL should be better if the ligament is strong. The intraoperative assessment of the macroscopic appearance of the ACL reflects the histological state of the PCL.     

Macroscopic and histological assessments of the cruciate ligaments in arthrosis of the knee

We examined the macroscopic appearance of both cruciate ligaments in 52 knees during knee replacement. It was classsified as normal, abnormal or ruptured. The ligaments were also evaluated histologically: stage 0 (normal), stage 1 (degeneration of < 1/3 of the collagen fibers), stage 2 (degeneration of 1/3-2/3) and stage 3 (> 2/3). 17 anterior cruciate ligaments (ACL) were normal, 14 were abnormal and 21 ruptured. All the posterior cruciate ligaments (PCL) were normal. 14 ACL were stage 0, 6 stage 1, 8 stage 2 and 24 were stage 3. 22 PCL were stage 0, 14 stage 1, 13 stage 2 and 3 were stage 3. When the ACL was abnormal or ruptured, the PCL was stage 0 only in one fourth of the cases. The long-term results of TKR retaining the PCL should be better if the ligament is strong. The intraoperative assessment of the macroscopic appearance of the ACL reflects the histological state of the PCL.     

Nonuniform distribution of collagen density in human knee ligaments

It is generally recognized that the mechanical properties of soft connective tissues are affected by their structural components. We documented collagen density distributions in human knee ligaments to quantify differences in density within and between these ligaments. In order to explain the variations in mechanical properties within and between different knee ligaments as described in the literature, the distributions of collagen density were correlated with these biomechanical findings. Human knee ligaments were shown to be nonhomogeneous structures with regard to collagen density. The anterior bundles of all ligaments contained significantly more collagen mass per unit of volume than the posterior bundles did. The percentage differences between the anterior and posterior bundles, in relation to the posterior bundles, were about 25% for the anterior cruciate ligament (ACL) and the collateral ligaments and about 10% for the posterior cruciate ligament (PCL). Along the cruciate ligaments, the central segments had higher collagen densities than did segments adjacent to the ligament insertions (ACL 9%, PCL 24%). The collagen density in the ACL was significantly lower than that in the other ligaments. These variations within and between the ligaments correlate well with the variations in mechanical properties described in the literature; however, other structural differences have to be taken into account to fully explain the variations in mechanical properties from the structural components.     

Histologic evaluation of posterior cruciate ligaments from osteoarthritic knees

It is controversial whether posterior cruciate ligament-retaining or posterior cruciate ligament-sacrificing (-substituting) implants should be used in total knee arthroplasty. The use of posterior cruciate ligament-retaining implants implies that the residual ligament is functional, and presumably normal, but few studies have been conducted to elucidate the histologic appearance of the posterior cruciate ligament taken from osteoarthritic knees. The purposes of the current study were (1) to evaluate the histologic appearance of posterior cruciate ligaments excised from osteoarthritic knees during primary total knee arthroplasty and to compare their appearance with posterior cruciate ligaments from knees of cadavers that were not operated on; and (2) to determine whether a correlation exists between the histologic appearance of the posterior cruciate ligament and the clinical status of the patients studied. Twenty-six posterior cruciate ligament specimens from patients with osteoarthritis and four specimens from cadavers were evaluated with the use of light and electron microscopy. Posterior cruciate ligaments from osteoarthritic knees showed greater degeneration than those from cadavers by light microscopy. Age greater than 60 years was associated with decreased collagen diameter in posterior cruciate ligaments from osteoarthritic knees as determined by electron microscopy. With the number of specimens available, the authors could not find a significant correlation between tibiofemoral alignment and mean collagen diameter or percentage of collagen occupancy. The extent of tissue degeneration of the posterior cruciate ligament could not be predicted by clinical findings. Additional studies identifying the mechanical competency of the posterior cruciate ligament in osteoarthritis would be valuable.     

Differences in condition between the anterior and posterior cruciate ligament in rheumatoid arthritis]

In rheumatoid arthritis (RA) we examined the cruciate ligaments of 16 patients by the use of light- and transmission electron microscopy. Considerable differences between the anterior (ACL) and the posterior cruciate ligament (PCL) were observed. The ACL showed dramatic ultrastructural changes, against that the PCL was compact and well conserved. The preservation of PCL in joint surgery can morphologically be recommended. Perhaps the greater inflammatory process on the surface of ACL is responsible for the observed differences.     

The posterior cruciate ligament and rotatory knee instability. An experimental study

The importance of the posterior cruciate ligament in relation to valgus-varus and axial rotatory stability in the knee joint was investigated. Mobility patterns were drawn from 20 osteoligamentous preparations after successive transection of the posterior cruciate ligament (PCL), the medial and lateral collateral ligaments, and the posterior joint capsule. The knee joint remained grossly stable after isolated transection of the PCL, and further cutting of either one of the collateral ligaments or of the posterior capsule yielded no greater instability than one should expect from isolated cutting of each of these structures. The posterior cruciate ligament was the stabilizing factor in flexion and external rotation after injury to the lateral collateral ligament and the posterolateral capsule, and it restricted internal rotation after cutting of the medial cruciate ligament and the posteromedial capsule. Valgus instability was markedly increased during the whole range of movement when PCL was included in injury to the medial compartment ligaments, and when included in a lateral compartment injury a further varus instability was found, though only in the flexed or semiflexed knee. No hyperextension could be demonstrated after these injuries.     

Complete knee dislocation without posterior cruciate ligament disruption. A report of four cases and review of the literature.

Complete knee dislocation usually causes disruption of both the anterior and posterior cruciate ligaments. Four cases of complete knee dislocation without posterior cruciate ligament (PCL) disruption are reported. All cases involved either anterior or anteromedial dislocation with anterior cruciate ligament disruption and collateral ligament injury, but without posterior cruciate disruption. This is an uncommon finding in complete dislocation of the knee. The PCL may occasionally be spared significant injury in anterior type dislocations, however, thus favorably affecting treatment options.     

Simultaneous measurement of changes in length of the cruciate ligaments during knee motion

The changes in length of electrolyte-in-rubber strain-gauge transducers implanted along the fibers of the anterior (ACL) and posterior (PCL) cruciate ligaments of the human anatomic specimen knees were measured simultaneously and continuously during knee motion. In unconstrained flexion and extension of the knee, all transducers in the ACL showed the maximum shortening peak at about 30 degrees flexion. After this, the length of the transducers in the anterior bundle increased, whereas those in the posterior bundle remained shortened. Transducers in the anterior and posterior bundles of the PCL, on the other hand, showed maximum lengthening peaks at approximately 50 degrees and 0 degrees flexion, respectively. The middle bundle of the PCL showed a smaller change. When simulated quadriceps forces were applied, the transducers in the ACL lengthened and those in the PCL shortened. At more than 90 degrees, however, the changes in length decreased. After cutting the ACL, the quadriceps force increased the shortening of the PCL.     

Dysplasia of the cruciate ligaments: radiographic assessment and classification

BACKGROUND: A common pathologic finding in the knee associated with congenital longitudinal deformity is aplasia of one or both cruciate ligaments. We performed a radiographic analysis to assess the changes in the femoral intercondylar notch and the tibial eminence in relation to the status of the cruciate ligaments. METHODS: Thirty-four knees in thirty-one patients with longitudinal congenital deficiency of the lower limb were evaluated. The cruciate ligaments and the associated abnormalities of the distal aspect of the femur and the proximal aspect of the tibia were evaluated with use of magnetic resonance imaging and a tunnel view radiograph. RESULTS: We differentiated three main types of dysplasia of the cruciate ligaments with typical associated changes. In type I, partial closure of the femoral intercondylar notch and hypoplasia of the tibial eminence are observed and the anterior cruciate ligament is hypoplastic or aplastic. In type II, these findings are accentuated and there is additional hypoplasia of the posterior cruciate ligament. In type III, the femoral intercondylar notch and the tibial eminence are completely absent and there is aplasia of both cruciate ligaments. CONCLUSIONS: We delineated three types of congenital deficiency of the cruciate ligaments and found corresponding morphologic changes of the femoral notch and the tibial eminence, which can be observed on tunnel view radiographs. Thus, the diagnosis and differentiation between aplasia of one or both cruciate ligaments and between congenital and trauma-induced absence of the cruciate ligaments may be made by interpreting plain radiographs.     

Double-contrast CT arthrography of the cruciate ligaments

The value of computed tomography (CT) in evaluating the cruciate ligaments was assessed by studying an amputated knee in order to find the most suitable position for detecting minimal defects of the ligaments. The ACL or PCL, or both, of 60 patients (61 knees) were then examined by CT and the findings were compared with those of arthroscopy. Defects 3mm in length were shown by CT. A sufficient quantity of air and an adequate amount of positive contrast medium were required to obtain an accurate picture of the ligaments. For the ACL, the sensitivity of CT was 96.6%, specificity was 95.5%, and accuracy was 96.1%. For the PCL, sensitivity was 78.6%, specificity was 91.7%, and accuracy was 84.6%. Ruptures of the cruciate ligaments shown by CT were classified into four types. Their CT images coincided significantly with their arthroscopic findings. This study shows double-contrast CT arthrography to be a valuable method for evaluating the cruciate ligaments, and especially the ACL.     

How to treat knee ligament injuries?

Indications for conservative treatment of knee ligament injuries can be established for all grade I or II sprains (partial tears), as well as isolated grade III sprains (complete tears) of the posterior cruciate ligament (PCL) and medial collateral ligament (MCL). These injuries should be treated with immediate mobilization. Only in isolated partial anterior cruciate ligament (ACL) tears without a positive pivot shift phenomenon is conservative treatment justified. However, many of these injuries may require operative reconstruction later. In complete ACL tears the surgical treatment consists of primary reconstruction or augmented primary repair. Today, the middle third of the patella tendon with the bone blocks is regarded as the "gold standard" for augmented repairs and late reconstructions. For the present, there is no place for synthetic prostheses in the treatment of an acute ACL rupture. Allograft replacement of the ACL must now be considered an experimental procedure. In the reconstruction of the PCL the above mentioned patella tendon graft is also preferable. Lateral collateral ligament (LCL) tears, especially if they are combined with ruptures of posterolateral ligament complex, should be repaired immediately after the injury. In these injuries late reconstructions are difficult and the results are poor. Conservative treatment of partial tears and postoperative treatment of reconstructed ligaments is twofold: on the one hand, the healing tissue should be protected and on the other hand, atrophy and wasting of uninjured tissue should be avoided. Overload and stretching of the injured ligaments should be eliminated with the aid of a suitable knee brace, but early range of motion exercises of the knee are allowed immediately.(ABSTRACT TRUNCATED AT 250 WORDS)     

Orientation changes in the cruciate ligaments of the knee during skeletal growth: A porcine model

Musculoskeletal injuries in pediatric patients are on the rise, including significant increases in anterior cruciate ligament (ACL) injuries. Previous studies have found major anatomical changes during skeletal growth in the soft tissues of the knee. Specifically, the ACL and the posterior cruciate ligament (PCL) change in their relative orientation to the tibial plateau throughout growth. In order to develop age‐specific treatments for ACL injuries, the purpose of this study was to characterize orientation changes in the cruciate ligaments of the Yorkshire pig, a common pre‐clinical model, during skeletal growth in order to verify the applicability of this model for pediatric musculoskeletal studies. Hind limbs were isolated from female Yorkshire pigs ranging in age from newborn to late adolescence and were then imaged using high field strength magnetic resonance imaging. Orientation changes were quantified from the magnetic resonance images using image segmentation software. Statistically significant increases were found in the coronal and sagittal angles of the ACL relative to the tibial plateau during pre‐adolescent growth. Additional changes were observed in the PCL angle, Blumensaat angle, intercondylar roof angle, and the aspect ratio of the intercondylar notch. Only the sagittal angle of the ACL relative to the tibial plateau experienced statistically significant changes through late adolescence. The age‐dependent properties of the ACL and PCL in the female pig mirrored results found in female human patients, suggesting that the porcine model may provide a pre‐clinical platform to study the cruciate ligaments during skeletal growth. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2725–2732, 2017.

     

Coordination of the anterior and posterior cruciate ligaments in constraining the varus–valgus and internal–external rotatory instability of the knee

 Tension along both cruciate ligaments was measured simultaneously under various loading conditions, and the interaction of these ligaments as constraints on knee instability was analyzed. Six fresh cadaveric knees were used. The attachments for both cruciate ligaments were detached from the femur and reattached to their original positions using metal plates equipped with 12 strain gauges. Each knee was moved under various loading conditions, and changes in tension along the cruciate ligaments were recorded simultaneously using the output of the strain gauges. Under varus torque, tension along the anterior cruciate ligament increased near full extension whereas that along the posterior cruciate ligament increased near 90° of flexion. Similar results were obtained under valgus torque. Under internal rotatory torque, a pattern similar to that under varus torque was also observed. Under external rotatory torque, no remarkable changes in tension were observed along either cruciate ligament. Thus, we conclude that both the anterior cruciate ligament and the posterior cruciate ligament cooperate to control varus–valgus and internal rotatory instabilities of the knee, and that the constraining function is transferred from the anterior cruciate ligament to the posterior cruciate ligament as the knee joint is flexed. Received: July 30, 2001 / Accepted: January 7, 2002     

Arthroscopic decompressive medial release of the varus arthritic knee: Expanding the functional envelope

We present the rationale and technique for treating medial knee osteoarthritis by dynamically unloading the medial compartment of the knee. Recent advances in kinematic studies indicate a dynamic linkage between differing degrees of freedom in the knee joint. Both the adduction moment and the foot progression angle are important determinants of medial compartment loading. The medially osteoarthritic knee has progressive compromise of free motion in more than 1 plane. Arthroscopic decompressive medial release unloads the medial compartment by release of the medial capsule and medial collateral ligament in the presence of intact cruciate ligaments, which may allow a decreased adduction moment and decrease of the external rotation restraint in extension found in more severely osteoarthritic knees. A case series of 38 patients with medial gonarthrosis was treated by this technique at the Hermanos Ameijeiras Hospital in Havana, Cuba. All patients had good results without postoperative valgus instability or significant complications. We feel that this technique warrants further clinical and biomechanical study for its use in isolation or in combination with high tibial osteotomy or minimally invasive selective osteotomy for the treatment of medial gonarthrosis of the knee. A minimally invasive, selective approach to biomechanical factors in osteoarthritis may be combined with other modulating techniques in efforts to forestall or prevent the need for total joint replacement.Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 17, No 5 (May-June), 2001: pp 523–526     

Patient preferences in knee prostheses

A total of 344 patients underwent bilateral total knee replacement (TKR) using a different prosthesis on each side. Four knee prostheses were used: anterior and posterior cruciate-retaining (ACL-PCL), posterior cruciate-retaining (PCL), medial or lateral pivot (MLP), and posterior cruciate-substituting (PS). All patients had good or excellent results. The range of movement, relief from pain, alignment, and stability did not vary among any of the prostheses. Forty-one of 46 patients (89%) preferred the ACL-PCL to the PS knee and 27 of 35 patients (77%) the MLP knee to the PS knee. Of the patients with an ACL-PCL knee on one side and a MLP on the other, an equal number preferred each type. The MLP knee was preferred to the PCL by 34 (79%) patients. PS and PCL knees were preferred equally. Patients with bilateral TKRs preferred retention of both their cruciate ligaments or substitution with a medial or lateral pivot prosthesis.     

Neural system of the human posterior cruciate ligament in osteoarthritis

The purpose of this study was to quantify the neural elements in a group of posterior cruciate ligaments from osteoarthritic patients in comparison with normal subjects. Nine ligaments obtained from total knee arthroplasty procedures and five control ligaments from amputated limbs or fresh cadavers were stained with gold chloride. The percentage area occupied by the receptors and the neural network was determined by means of a computer-assisted image analyzer. A significant reduction of the neural elements was observed in the group of ligaments from osteoarthritic patients (0.44 ± 0.132 SEM vs 0.958 ± 0.13 SEM, P = .001). The loss of mechanoceptors and the consequent reduction of neural afterences may reduce the functional stability of the joint, participating in the osteorthritic degenerative process.     

Isolierte und kombinierte Kniebandverletzungen

Complex knee ligament injuries are characterized by simultaneous rupture of the anterior cruciate ligament (ACL) and/or the posterior cruciate ligament (PCL) and at least one collateral ligament. Isolated injury to the medial collateral ligament (MCL) and PCL have a high healing capacity and can be treated conservatively in many cases. Ruptures of the MCL can also be treated conservatively in complex injuries if the cruciate ligaments are reconstructed. Ruptures of the lateral structures usually need surgical reconstruction. Indications for acute surgical repair include meniscus dislocation, entrapment of collateral ligament portions in the joint, knee dislocation with severe knee instability, and displaced bony avulsions. The anatomy of the knee ligaments must be carefully respected in surgical reconstruction. Acute repair of collateral ligament injuries is possible only in the first 2 weeks after trauma. Acute arthroscopy is indicated only in combination with reconstructive surgery.     

Vascular physiology and long-term healing of partial ligament tears.

Functional outcomes of anterior cruciate ligament (ACL) injury are generally poorer than those of medial collateral ligament (MCL) tears. Following ligament damage, all phases of ligament healing require an adequate blood supply. We hypothesized that the differences in healing properties of the ACL and MCL would reflect their vascular responses to joint injury. This paper examines the long-term changes in blood flow and vascular volume of rabbit knee ligaments after direct injury, and under conditions of chronic joint instability induced by section of the posterior cruciate ligament (PCL). Standardized injuries were surgically induced in adult rabbit knee ligaments: partial MCL transection, partial ACL transection, or complete PCL transection (joint instability). Sixteen weeks later the blood flow and vascular volume of the ACL and MCL were measured and compared to control and sham-operated animals. Direct ligament injury induced significant increases in standardized blood flow and vascular volume of both ACL and MCL after 16 weeks; however, the vascular volume of the ACL was not higher than the control levels in the MCL. We conclude that direct injury to both the anterior cruciate and MCLs induces long-term physiological responses. Joint laxity is a common sequel to PCL injury. Chronic joint laxity failed to induce adaptive vascular responses in the ACL, while the MCL shows significant amplification of blood supply. Although both MCL and ACL showed increased weight after PCL transection, the lack of a long-term vascular response in the ACL may be a major factor in its the diminished healing potential.     

人工膝关节置换术后关节线改变的临床研究

目的观察选择保留后交叉韧带的膝关节表面置换术与不保留周围韧带的旋转膝关节置换术后关节线的改变,分析其发生原因及预防方法。方法分别选择保留后交叉韧带的膝关节表面置换术患者25例,不保留周围韧带的旋转膝关节置换患者25例,手术前、后均拍摄膝关节非负重侧位片。术前的侧位片上,平行于胫骨平台负重关节面作一条直线,测量它到胫骨结节的垂直距离（JL）;在术后的侧位片上,平行于胫骨假体负重关节面作一条直线,测量它到胫骨结节的垂直距离（JL’）。JL’和JL之间的差值（JL’-JL）为手术前后关节线的变化值,对其进行统计学处理并分析原因。结果保留后交叉韧带的膝关节表面置换后,JL’-JL为2．0mm（-1．3—7．2mm）,其中5例大于2mm;旋转膝关节置换后,JL’-JL为3．1mm（-1．5—12．3mm）,其中11例大于2mm,两者差异有统计学意义（P〈0．01）。表面置换时关节线升高的原因包括胫骨近端截骨过少、韧带的过度松解、增加股骨远端截骨、股骨假体前后径偏小等;旋转膝关节置换时,关节线的改变主要由骨缺损和缺乏韧带的限制作用所致。结论保留后交叉韧带膝关节表面置换时,虽然有某些原因可以造成关节线的改变,但是由于畸形和骨缺损相对较轻,同时周围韧带的相对完整使其关节线发生改变的几率小、程度轻。由于骨缺损相对较重,同时手术中不保留周围韧带,旋转膝关节置换时更易发生关节线位置异常,应该通过股骨内上髁等骨性标志帮助恢复正常的关节线水平。