Stress radiography in the diagnosis of anterior cruciate ligament deficiency

Summary A prospective study was carried out to test the sensitivity and specificity of stress radiography in detecting anterior cruciate ligament deficiency in both knees of 116 patients using the Telos device. In 47 of these a total or partial rupture of the anterior cruciate ligament was diagnosed by arthroscopy, while the ligament was intact in the remaining 69 patients. The mean difference in radiological translation between the injured and the normal knee was greater than 5 mm (p<0.001) in those with anterior cruciate deficiency, and less than 3 mm in the others. A differential displacement of up to 3 mm was considered normal. The sensitivity of the method was less than 67% and the specificity was 100%. Clinical diagnosis had a sensitivity of 70.2% and a specificity of 98.5%. Our findings suggest that, although a differential translation of more than 3 mm can be diagnostic, smaller differences do not rule out anterior cruciate deficiency.

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Résumé Les auteurs ont réalisé une étude prospective pour évaluer la sensibilité et la spécificité des radiographies en position forcée dans le diagnostic des insuffisances du ligament croisé antérieur (LCA). Une radiographie en tiroir forcé des deux genoux a d'abord été faite, en utilisant l'appareil Telos, chez 116 patients devant subir une arthroscopie unilatérale. Chez 47 de ces patients une rupture totale ou partielle du LCA a été confirmée par arthroscopie, qui a montrée un ligament intact chez les 69 autres. La différence moyenne de translation entre le genou blessé et le genou sain a été supérieure à 5 mm (p<0.001) chez les patients ayant une insuffisance du LCA et inférieure à 3 mm chez les autres (une différence de 3 mm a été considérée comme normale). La sensibilité de la méthode a été de moins de 67% et le spécificité de 100%. L'examen clinique a une sensibilité de 70.2% et une spécificité de 98.5%. Ces résultats permettent de penser que, bien qu'une translation supérieure à 3 mm puisse avoir une valeur diagnostique, une moindre différence n'exclut pas une insuffisance du ligament croisé antérieur.

     

The axial view in evaluating tibial translation in cases of insufficiency of the posterior cruciate ligament.

The purpose of this report is to present a new radiological method of diagnosis and evaluation of posterior instability using the patellofemoral axial view. During a period of 22 months, we performed clinical and radiological assessments on 20 patients (6 acute and 14 chronic) with isolated posterior instability caused by posterior cruciate ligament (PCL) rupture and on 20 patients with normal knees. The radiological examination included stress radiographs using the Telos device (Telos, Griesheim, Germany) as well as a modification of the routine axial patellofemoral view. Both diagnosis and quantification of the posterior tibial translation was possible in all cases by measuring, on the axial view, the distance between the anterior edge of the tibial plateau and the center of the femoral groove (trochlea). Clinical examination, conventional radiography, KT-1000 arthrometry, stress radiography at 90 degrees and at 20 degrees of flexion, and magnetic resonance imaging all assist in diagnosing a PCL tear. This new radiographic technique is simple, fast, and consistently effective both in patients with acute and those with chronic PCL tears, as well as in those who have undergone PCL reconstruction.     

Quantitative stress radiography for diagnosis of anterior cruciate ligament deficiency

Summary A portable stress-applying device for stress radiography was developed for daily clinical use. Using this device, stress radiography for the diagnosis of the anterior cruciate ligament (ACL) deficiency was performed with the knee flexed at 20° and at 90°. A 100-N force was chosen as a standardized stress. The subjects were classified into four groups: the manually tested ACL-deficient group (32 knees), the manually tested control group (80 knees), the instrumentally tested ACL-deficient group (14 knees), and the instrumentally tested control group (34 knees). There was no statistical difference in the reliability (sensitivity, specificity, and accuracy) of stress radiography between the manual technique and the instrumental technique. When stress radiography with the knee flexed at 20° and that at 90° were compared, the former was more reliable than the latter. As the manual technique is compromised by a lack of standardization in applied force, a mechanical device is required in quantitative stress radiography. The reliability of stress radiography with the knee flexed at 20° is considered high enough to warrant dispensing with further stress radiography with the knee flexed at 90° for diagnosing ACL deficiency.     

后交叉韧带胫骨止点与双束重建胫骨骨道定位的临床解剖学研究

目的 解剖研究后交叉韧带(PCL)胫骨止点情况,确定PCL前外侧束(ALB)与后内侧束(PMB)胫骨止点的位置、形状与面积,探讨PCL双束四骨道重建中胫骨骨道定位标志与定位方法.方法 30例成人膝关节标本,根据屈伸膝关节过程中纤维束紧张与松弛情况,将PCL分为ALB与PMB,并确定各束中的功能束,用多种指标测量ALB、PMB与功能束的胫骨止点,解剖寻找双束四骨道重建PCL中胫骨骨道定位标志与定位方法.结果 PCL胫骨止点位于后髁间窝内,其纵轴由近内斜向远外,与胫骨干夹角平均为(16.5±1.4)°.ALB与PMB胫骨止点基本呈远近排列,ALB胫骨止点接近于菱形,平均面积为(90±20)mm2,PMB胫骨止点近似长方形,平均面积(96±32)mm2,二者无显著差异(P>0.05).ALB与PMB中均存在功能束,分别止于ALB胫骨止点的远外侧部及PMB胫骨止点的远内侧部,均接近椭圆形,面积分别为(35±12)mm2与(36±6)mm2,二者无显著差异(P>0.05).ALB功能束胫骨止点中心与PMB功能束胫骨止点中心距离为(12.7 ±1.9)mm.胫骨内、外侧髁间棘及胫骨上端后方骨嵴为重要的解剖标志.结论 PCL胫骨止点可以容纳两个胫骨骨道,PCL的ALB与PMB中均存在功能束,提示临床双束四骨道重建PCL时,胫骨骨道应分别定位于ALB与PMB功能束胫骨止点处.     

The effect of isometric graft posterior cruciate ligament reconstruction on anterior tibial translation

Eight fresh-frozen cadaver knees were studied to evaluate whether an isometrically placed posterior cruciate ligament (PCL) graft restores normal posterior tibial translation without overconstraining anterior tibial translation. Each knee was tested with a three-axis load cell in the intact state, after PCL sectioning, and after PCL reconstruction. After PCL reconstruction, posterior tibial displacement was restored to values observed in the intact state for all flexion angles except 60 degrees and 90 degrees. Anterior tibial translation was not significantly changed for any of the three states. These results indicate isometric reconstruction of the PCL significantly reduces posterior tibial translation without overconstraining anterior tibial translation.     

The long-term effects of tibial drill hole position on the outcome of anterior cruciate ligament reconstruction.

Fifty-three cases of anterior cruciate ligament reconstruction were classified into two groups depending on the tibial drill hole position: in the anterior group, the center of tibial drill hole was positioned anteriorly to the dome of the intercondylar notch (Blumensaat's line), and in the posterior group, it was positioned posteriorly to the Blumensaat's line. Knee extension loss in the anterior group was significantly greater at 1 and 2 years postoperatively than that of the posterior group. However, there were no differences between the anterior and posterior groups 3 to 5 years postoperatively. No significant differences in anterior laxity were seen from 1 to 4 years postoperatively. After more than 5 years, anteroposterior translation of the anterior group was significantly greater than that of the posterior group. In the anterior group, extension was restricted in the early postoperative period. At latest follow-up more than 5 years postoperatively, anterior laxity in the posterior group was significantly less than that in the anterior group.     

The medial meniscal root as a landmark for tibial tunnel position in posterior cruciate ligament reconstruction

As a result of improved basic science knowledge and operative techniques, posterior cruciate ligament (PCL) reconstructions have steadily increased over the past 10 years. Even for the experienced arthroscopist, PCL reconstruction surgery can be technically challenging and fraught with complications. The most technically demanding aspect of the procedure may be placement and drilling of the tibial tunnel. Reasons for this include unfamiliarity with the posterior aspect of the knee, neurovascular risk, and the relative infrequency of the procedure being performed by most surgeons. We propose that the root of the posterior horn of the medial meniscus is an easily identifiable visible landmark that can not only aid in the localization of the position of the tibial tunnel in PCL reconstruction but also assist navigation in the posterior aspect of the knee arthroscopically.     

Femoral and tibial tunnel position using a transtibial drilled anterior cruciate ligament reconstruction technique

This study evaluates the position of the femoral tunnel, which is achieved using a transtibial, single-bundle anterior cruciate ligament (ACL) reconstruction technique. The radiographs of 50 consecutive, primary single-bundle ACL reconstructed knees using this technique were reviewed. The angle between the femoral tunnel and the apex of the intercondylar notch was recorded. The average angle from the 12-o'clock vertical position to the femoral tunnel was 49 degrees (range, 39 degrees-59.2 degrees; SD = 3.9), corresponding to the 10:20 position on a clock face for a right knee. These results demonstrate that it is technically possible to create an obliquely oriented single-bundle femoral tunnel at approximately the 10:20 position through a tibial tunnel angled approximately 60 degrees from the proximal tibial joint surface. This correlates to a femoral tunnel approximately midway between the anteromedial and posterolateral bundle origins of the ACL.     

Anterior tibial translation during different isokinetic quadriceps torque in anterior cruciate ligament deficient and nonimpaired individuals

STUDY DESIGN: Factorial quasi-experimental design. OBJECTIVES: To quantify the effect of different levels of isokinetic concentric and eccentric knee extensor torques on the anterior tibial translation in subjects with anterior cruciate ligament (ACL) deficiency. Electromyogram (EMG) activity of 4 leg muscles was recorded in order to detect any co-activation of extensors and flexors. BACKGROUND: The rehabilitation after an ACL injury is of importance for the functional outcome of the patient. In order to construct a rehabilitation program after that injury, it is important to understand the in vivo relationships between muscle force and tibial translation. METHODS AND MEASURES: Twelve patients with unilateral ACL injury and 11 uninjured volunteers performed 36 repetitions of a quadriceps contraction at different isokinetic concentric and eccentric torque levels, on a KinCom machine (60 degrees x s(-1)), with simultaneous recordings of tibial translation (CA-4000) and EMG activity from quadriceps and hamstrings muscles. Tibial translations and EMG levels were normalized to the maximum of each subject. RESULTS: The individual anterior tibial translation increased with increased quadriceps torque in a similar manner in both quadriceps contraction modes in all legs tested. During concentric mode, translation was similar in all groups, but during eccentric mode, the mean translation was 38% larger in the ACL injured knees. No quadriceps-hamstrings co-activation occurred in any test or group. CONCLUSIONS: An ACL deficient knee can limit the translation within a normal space during concentric muscle activity but not during eccentric activity. That limitation depends on other mechanisms than hamstrings co-activation.     

Positioning of the tibial tunnel for anterior cruciate ligament reconstruction

Two mechanisms of unintentioanl anterior tibial tunnel axis shift can occur despite accurate placement of the guide wire within the proximal tibia. The first results from using a short-block reamer head joined to a shaft of smaller diameter. If the tibial tunnel is drilled obliquely, it is possible for the reamer head to displace anteriorly in the knee joint before completion of the posterior portion of the tibial tunnel. The second mechanism of anterior shift involves using two sequential drills to create the tibial tunnel. To delineate the causes of this unwanted shift, cadaveric studies and special roentgenographic studies were undertaken. Results demonstrated that the shift is related directly to the presence of high-density bone in the tibial plateau. In an effort to minimize this effect, various drill designs were tested, and it was determined that a drill-head length of 25 mm was most effective at reducing the shift without sacrificing the freedom of movement necessary to obtain precise endosteal placement of the femoral tunnel. Along with these experimental studies, a retrospective 7-year review of anterior cruciate ligament (ACL) reconstruction failures was performed to assess the clinical significance of inadvertent anterior positioning of the tibial tunnel.     

Soleus and gastrocnemius muscle loading decreases anterior tibial translation in anterior cruciate ligament intact and deficient knees

This study evaluated the effect of the gastrocnemius and soleus muscles on dynamic knee stability by studying the effect of passive calf muscle loading on anterior tibial translation in normal and anterior cruciate ligament (ACL) deficient knees. Anterior tibial translation was measured bilaterally in 12 anesthetized patients with unilateral ACL-deficient knees using a KT-1000 arthrometer. An ankle-foot orthosis was used to passively dorsiflex the ankle and generate tension in the calf muscles. As the ankle flexion angle was progressively changed from 30 degrees plantar flexion to 10 degrees dorsiflexion, anterior tibial translation decreased 43% and 37% with manual maximum force in normal and ACL-deficient knees, respectively (P < .0001). These findings suggest that the calf muscles may function as dynamic knee stabilizers. Anterior tibial translation also was measured in four cadaver knees. Significant decreases were seen in anterior tibial translation with progressive ankle dorsiflexion in ACL-intact specimens and after the ACL had been cut (P < .05). This effect persisted when the gastrocnemius muscle was cut, but was lost when the soleus muscle was released. The data suggest that the soleus muscle may play a role in dynamically stabilizing the knee.     

Measurement of changes in distance between the femoral and the tibial drill holes for the anterior cruciate ligament reconstruction

We have developed an experimental system in which a new Gallium-Indium containing transducer can continuously measure the changes of separation distances between the femoral and tibial points. The measurements provides information for the attachment location in the anterior cruciate ligament (ACL) reconstruction and used for various combinations of extra-articular and intra-articular methods. At the first experiment, the distance between each pair of points at the level of the capsule for fifteen combinations during simple flexion-extension knee motion were measured on six cadaveric knees. At the next experiment, in an ACL-deficient knee the distances of ten combinations in the intra-articular method were measured. These results indicated that for an isometric placement the combination of the center of tibial insertion and the postero-proximal of the femoral origin of the ACL appeared to furnish a better location for intraarticular reconstruction. No combination was recommended for extraarticular reconstruction.     

Partial tears of the anterior cruciate ligament. Progression to complete ligament deficiency

In a prospective seven-year study, we treated 32 patients with partial ruptures of the anterior cruciate ligament (ACL) verified by arthroscopy. Twelve knees (38%) progressed to complete ACL deficiency with positive pivot shift tests and increased anteroposterior translation on tests with the KT-1000 arthrometer. Patients with partial ACL tears frequently had limitation for strenuous sports, while those developing ACL deficiency had additional functional limitations involving recreational activities. Three factors were statistically significant in predicting which partial tears would develop complete ACL deficiency: the amount of ligament tearing--one-fourth tears infrequently progressed, one-half tears progressed in 50% and three-fourth tears in 86%; a subtle increase in initial anterior translation; and the occurrence of a subsequent re-injury with giving-way.     

Reduced anterior tibial translation associated with adaptive changes in the anterior cruciate ligament-deficient joint: goat model.

Adaptive changes in the menisci and adjacent posterior capsule were documented within anterior cruciate ligament-deficient knee (stifle) joints in the goat model. These physical changes in the menisci and capsule developed over time and were associated with reduction in the initial (time zero) abnormal anterior tibial translation following transection of the anterior cruciate ligament. At 50 N of applied force, the normal goat knee joint has a total anterior-posterior translation of 0.6+/-0.1 mm (+/- SEM) at 45 degrees of flexion and 0.3+/-0.1 mm at 90 degrees. The translation immediately after transection (time zero) with 50 N of force was 8.2+/-0.5 mm at 45 degrees and 4.9+/-0.9 mm at 90 degrees. Within 8 months after transection and at 50 N of force, the treated knees had reduced translation values of 5.3+/-0.6 mm at 45 degrees of flexion and 2.9+/-0.5 mm at 90 degrees, or 35 (p<0.001) and 40% reductions, respectively, compared with the values at time zero. Magnetic resonance images of the ligament-deficient stifle joints, as well as gross measurements and image analysis after dissection, consistently demonstrated increases in cross-sectional area and volume of the menisci compared with the contralateral controls. These secondary changes were most pronounced in the posterior portion of the medial menisci, and histologic evaluation demonstrated hypercellularity with the accumulation of poorly organized collagen, reduced safranin O staining (proteoglycan matrix synthesis), a thickened capsule and capsule attachment, and increased vascularity at the meniscal capsule interface.     

Value of posterior cruciate ligament index in the diagnosis of anterior cruciate ligament injuries

Assessment of the diagnostic value of the posterior cruciate ligament index (PCL index) for injuries of the anterior cruciate ligament (ACL) was done. Magnetic resonance imaging (MRI) and knee joint arthroscopy of 170 patients were evaluated. The shortest distance between the femoral and tibial attachment of PCL (x) and the distance from that line to the tip of the arc marked by the PCL (y) on the sagittal plane images were measured. The quotient of these two parameters (x/y) defined the PCL index. In 100 patients, for whom arthroscopy ruled out ACL injury, the mean PCL index was 5.01 +/– 0.76. In 30 patients in whom arthroscopy showed total ACL rupture, the mean PCL index was 2.88 +/– 0.74, and in 10 patients with ACL partial rupture, 3.09 +/– 0.23. The conclusion is that injury to the ACL changes the PCL index markedly. In diagnostically unreliable MR images, deterioration of the PCL index could help in the diagnosis of ACL injury. Received: 19 July 1996     

The effects of tibial rotation on posterior translation in knees in which the posterior cruciate ligament has been cut

BACKGROUND: One of the most useful clinical tests for diagnosing an isolated injury of the posterior cruciate ligament is the posterior drawer maneuver performed with the knee in 90 degrees of flexion. Previously, it was thought that internally rotating the tibia during posterior drawer testing would decrease posterior laxity in a knee with an isolated posterior cruciate ligament injury. In this study, we evaluated the effects of internal and external tibial rotation on posterior laxity with the knee held in varying degrees of flexion after the posterior cruciate and meniscofemoral ligaments had been cut. MATERIALS AND METHODS: Twenty cadaveric knees were used. Each knee was mounted in a fixture with six degrees of freedom, and anterior and posterior forces of 150 N were applied. The testing was conducted with the knee in 90 degrees, 60 degrees, 30 degrees, and 0 degrees of flexion with the tibia in neutral, internal, and external rotation. All knees were tested with the posterior cruciate and meniscofemoral ligaments intact and transected. Repeated-measures analysis of variance was used for statistical analysis. RESULTS: At 30 degrees, 60 degrees, and 90 degrees of flexion, there was a significant increase in posterior laxity following transection of the posterior cruciate and meniscofemoral ligaments. At 60 degrees and 90 degrees of flexion, there was significantly less posterior laxity when the tibia was held in internal compared with external rotation. At 0 degrees and 30 degrees of flexion, there was no significant difference in posterior laxity when the tibia was held in internal compared with external rotation. CONCLUSIONS: After the posterior cruciate and meniscofemoral ligaments had been cut, posterior laxity was significantly decreased by both internal and external rotation of the tibia. Internal tibial rotation resulted in significantly less laxity than external tibial rotation did at 60 degrees and 90 degrees of knee flexion.     

Radiographic evaluation of anterior cruciate ligament graft failure with special reference to tibial tunnel placement

Graft failure in anterior cruciate ligament (ACL) reconstruction can result from anterior placement of the tibial tunnel. Conventional radiographic evaluation of this problem does not take into account potential changes in tibio-femoral relationship caused by ACL instability. A retrospective radiographic evaluation of failed as well as successful ACL reconstructions was carried out. Both published radiographs as well as those obtained of patients treated by the authors were evaluated for tibial tunnel placement, roof impingement, and tibial position relative to the femur. In the second part of the study, the radiographs were obtained under standard conditions in both failed ACL reconstructions and normal knees. The results of both parts of the study indicate that lateral radiographs of the extended knee with ACL instability are likely to show subtle anterior tibial subluxation. The subluxation can give the impression of roof impingement on the graft. However, the majority of the failed knees had similar tibial tunnel placement compared with successful reconstructions and would appear unimpinged once corrected for subluxation. The diagnosis of graft impingement by the femoral intercondylar roof has to take into account potential tibial subluxation. Impingement as a cause graft failure may be less common than previously thought.Arthroscopy 1998 Mar;14(2):206-11     

Isolated posterior cruciate ligament insufficiency induces morphological changes of anterior cruciate ligament collagen fibrils.

We studied the ultrastructural changes of the human anterior cruciate ligament (ACL) with transmission electron micrograph cross-sections following isolated posterior cruciate ligament (PCL) injury. Biopsy specimens were obtained from the proximal third and anteromedial aspect of the ACL. Fourteen patients with PCL-deficient knees at a mean of 22.1 months from injury to surgery and 5 normal knees amputated secondary to malignant tumors or traumatic injuries were used as controls. A significant difference was found in the number of collagen fibrils per 1 microm2 between the PCL-deficient knee group and the control group. There was a significant difference found in the collagen fibril diameter between the PCL-deficient knee group and the control group. The collagen packing density (the percentage of sampled area occupied by collagen fibrils) was also significantly different between the PCL-deficient knee and the control group. The current study shows that an isolated PCL insufficiency can induce morphological changes in ACL collagen fibrils, suggesting that a PCL insufficiency can have adverse effects on other ligamentous structures in the knee joint.     

Posterior cruciate ligament balancing in total knee replacement: the quantitative relationship between tightness of the flexion gap and tibial translation

We have examined the relationship between the size of the flexion gap and the anterior translation of the tibia in flexion during implantation of a posterior cruciate ligament (PCL)-retaining BalanSys total knee replacement (TKR). In 91 knees, the flexion gap and anterior tibial translation were measured intra-operatively using a custom-made, flexible tensor-spacer device. The results showed that for each increase of 1 mm in the flexion gap in the tensed knee a mean anterior tibial translation of 1.25 mm (SD 0.79, 95% confidence interval 1.13 to 1.37) was produced. When implanting a PCL-retaining TKR the surgeon should be aware that the tibiofemoral contact point is related to the choice of thickness of the polyethylene insert. An additional thickness of polyethylene insert of 2 mm results in an approximate increase in tibial anterior translation of 2.5 mm while the flexed knee is distracted with a force of between 100 N and 200 N.     

膝后交叉韧带胫骨止点撕脱性骨折的治疗

后交叉韧带胫骨止点撕脱性骨折较少见,常属于严重暴力损伤,早期易误诊及漏诊,影响膝关节功能.本院自1998年1月至2003年10月共收治22例,效果满意.单纯后交叉韧带损伤经膝关节MRI检查后另予韧带重建术处理,本文着重对后交叉韧带胫骨止点撕脱性骨折的采用改良膝后直切口优点和内固定的选择进行分析讨论.