***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Stress radiography presents the golden st and ard to quantify posterior laxity in posterior cruciate ligament ( PCL ) insufficiency . Several different techniques are currently available , but comparative data are insufficient . Different stress radiographic techniques result in different values for posterior laxity . Comparative controlled clinical study was design ed . Prior to PCL reconstruction 30 patients underwent a series of stress radiographs : Telos device , hamstring contraction , kneeling view , gravity view , and an axial view . Posterior displacement , side-to-side difference ( SSD ) , condyle rotation , required time , and pain were measured . Posterior displacement was : Telos 12.7 ± 3 mm ( SSD 10.6 ± 3.1 mm ) , hamstring contraction 11.2 ± 3.2 mm ( SSD 8.5 ± 3.4 mm ) , kneeling 14.4 ± 3.8 mm ( SSD 10.2 ± 3.5 mm ) , gravity view 10.5 ± 2.8 mm ( SSD 9.1 ± 2.4 mm ) , and axial view 19.4 ± 6.9 mm ( SSD 8.5 ± 4.1 mm ) . In comparison to Telos the hamstring contraction , gravity , and the axial view underestimated the SSD by approximately 2 mm . Telos and kneeling caused significantly more pain than all other techniques ( P < 0.001 ) . The axial view was fastest ( 115 s , P < 0.001 ) and Telos longest ( 305 s , P < 0.001 ) , respectively . Telos indicated the lowest rotational error with a significant difference between kneeling and gravity ( P < 0.003 ) . In contrast to Telos as the golden st and ard , hamstring contraction , gravity , and axial view underestimated the SSD . Kneeling and Telos are comparable with respect to SSD and pain . Although kneeling indicates a greater rotational error than Telos , it seems to be a reliable alternative for quantifying posterior tibial displacement in a more simple and fast way INTRODUCTION In patients with anterior cruciate ligament ( ACL ) tears , anterior laxity can be measured using stress radiographs or more recently introduced electronic measurement devices . HYPOTHESIS The GNRB ( ® ) arthrometer offers a radiation-free method of measuring anterior knee laxity whose diagnostic value is identical to that of Telos ( ® ) or Lerat stress radiographs . PATIENTS AND METHODS One hundred and fifty-seven patients ( 40 years [ 18 - 69 ] ) scheduled for knee arthroscopy were evaluated using the GNRB ( ® ) and two series of stress radiographs of both knees , one obtained using a 250-N Telos ( ® ) device and the other using the technique described by Lerat ( posterior translation of the femur/tibia under a 9-kg loading device ) . Arthroscopic evaluation of the ACL served as the reference st and ard for assessing the diagnostic performance of the radiological and instrumental laxity measurements . RESULTS Under arthroscopic examination , the ACL was normal in 50.3 % ; " healed to roof of the notch " ( partial tear ) in 9.6 % , " posterolateral bundle preserved " ( partial tear ) in 7.0 % , " healed to the posterior cruciate ligament " ( PCL ) in 17.8 % , and " empty notch " ( complete tear ) in 15.3 % . In partial ACL tears , no significant differences in anterior laxity were found across the three measurement techniques . Telos ( ® ) and GNRB ( ® ) laxities were greater in the complete-tear group than in the normal-ACL , partial-tear , and healed-to-PCL groups . With the Lerat technique , the only significant differences were between the complete-tear group and the normal-ACL and partial-tear groups . Telos ( ® ) and GNRB ( ® ) showed similar diagnostic performance ( sensitivity>62 % , specificity>75 % ) , whereas the Lerat technique lacked sensitivity ( sensitivity=43.2 % , specificity=82.7 % ) at 3 mm . DISCUSSION Diagnostic performance was lower in our study than in earlier reports . The GNRB ( ® ) performed as well as Telos ( ® ) . The non-irradiating nature of GNRB ( ® ) assessment s allows repeated measurements for therapeutic or diagnostic purpose s. LEVEL OF EVIDENCE Level III , prospect i ve case-control study Summary A prospect i ve 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 . RésuméLes auteurs ont réalisé une étude prospect i ve 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 In a prospect i ve , consecutive , clinical and stress radiographical study , comprising 153 traumatic knee injuries , the value of stress radiographical measurements , gonylaxometry , was studied .  Clinical evaluation , gonylaxometry and preoperative evaluation under general anaesthesia were carried out in that order . Then the operative findings were recorded as drawings on st and ard diagrams . These were used as a basis for evaluation of the preoperative tests . Of all the methods evaluated ,  gonylaxometry  was found to provide the most accurate information regarding the knee injury . Very close to this result were the findings under general anaesthesia . Anterior drawer sign was measured gonylaxometrically  when damage to the anterior cruciate ligament was present ; posterior drawer meant damage to the posterior cruciate ligament . Partial ruptures of cruciate ligaments did not allow antero-posterior displacements exceeding the critical levels of the test . Small positive medial instability was found with ruptures of profound medial structures , higher values with total rupture of the long superficial collateral b and , and still higher values when cruciate ligament ruptures were also present . The predictive values of a positive radiographical test were 100 per cent as regards medial instability and 98 per cent for drawer looseness . The predictive values of a negative test were 96 per cent for drawer and 92 per cent for medial instability . These figures are based on the total material . 95 per cent confidence limits are given INTRODUCTION The clinical diagnosis of the anterior cruciate ligament ( ACL ) tear is based on demonstrating anterior subluxation of the tibia on the femur . In any of the following perspectives , diagnostic ( cutoff value confirming rupture ) , prognostic ( treatment efficacy ) , and therapeutic ( laxity influencing the treatment ) , this laxity can be measured on stress X-rays . WORKING HYPOTHESIS The diagnostic value of dynamic radiographs is low for ACL rupture . Passive Telos ( ® ) X-rays have better diagnostic value , better radiologic quality , and are easier to carry out than active Franklin-type X-rays . MATERIAL AND METHODS A cohort of 112 patients ( 28 females , 84 males ; mean age , 33.7 years [ range , 18 - 72 years ] ) with an indication for knee arthroscopy were studied prospect ively . Before undergoing the arthroscopic treatment , two series of images of both knees were taken : one series of passive anterior drawer dynamic X-rays on a Telos ( ® ) device at 250 N and a series of active anterior drawer dynamic X-rays according to Franklin ( contraction of the quadriceps against 7 kg of weight at the ankle ) . The arthroscopic evaluation of the ACL ( reference status ) was compared to the anterior laxity measurements ( absolute and differential ) of each knee compartment ( medial , lateral , and average ) to determine the diagnostic value of the two radiological tests . RESULTS We found 70 patients with an " arthroscopically ruptured ACL " , 32 with an " arthroscopically healthy ACL " , and 10 with a " partial rupture " . The measurement of the anterior drawer values on the dynamic X-rays ( active and passive ) by two independent observers was reliable and reproducible ( ICC>0.80 ) , particularly when using the medial compartment ( ICC=0.96 ) and the differential values eliminating the interobserver measurement error and interindividual laxity variations . In terms of X-ray technique , the active images were more frequently painful and the radiographic result showed less good quality than the Telos images . The anterior drawer values in the " healthy ACL " group were significantly less than in the " ruptured ACL " group for the Telos ( ® ) images , whether the measurements were absolute or differential . For the Franklin images , this difference was only significant for the absolute values . Used for diagnosis ( 4-mm differential on the medial compartment ) , the passive dynamic images had lower diagnostic values ( Se=59 % and Sp=90 % ) than the series reported in the literature , which were marked by great heterogeneity . CONCLUSION The measurement of anterior drawer values on Telos ( ® ) and Franklin dynamic X-rays is a reliable and reproducible measurement , particularly when using the medial compartment and differential measurements . This small series did not demonstrate a diagnostic value for the Franklin images , contrary to the Telos ( ® ) X-rays . Used for diagnostic purpose s , the Telos ( ® ) images had a low sensitivity ; consequently , they should be used preferentially for prognostic or therapeutic purpose s. LEVEL OF EVIDENCE Level III , prospect i ve case-control study PURPOSE The objective of this study was to evaluate the efficacy of different stress radiography techniques in quantifying a posterior cruciate ligament ( PCL ) lesion .  TYPE OF STUDY Prospect i ve serial study . METHODS Sixty patients with subacute or chronic PCL injuries , confirmed using magnetic resonance imaging ( MRI ) or arthroscopic evaluation , were enrolled in this study . The patients underwent a KT-2000 ( Medmetric , San Diego , CA ) examination and a series of stress radiographs that included a radiographic posterior drawer test with Telos ( Telos , Weterstadt , Germany ) at 90 degrees and 25 degrees of knee flexion , an active radiograph at 90 degrees of knee flexion , and an axial view radiograph . RESULTS Stress radiography performed with Telos showed an average posterior tibial displacement of 11.54 + /- 4.93 mm and 7.97 + /- 3.16 mm at 90 degrees and 25 degrees , respectively . The active radiographs showed an average posterior tibial displacement of 11.48 + /- 5.14 mm . CONCLUSIONS Stress radiographs were shown to be superior to arthrometric evaluation in quantifying posterior tibial translation . The techniques performed with the knee at 90 degrees of knee flexion allowed for greater posterior tibial displacement and , consequently , an easier quantification of the degree of ligament insufficiency . Stress radiographs performed through hamstring contraction gave the same results as those performed with Telos at 90 degrees of knee flexion Seventy-one consecutive patients with posterolateral knee injuries had clinical stability testing abnormalities documented prospect ively . We compared these find ings with the incidence and patterns of their injuries documented at surgery . An abnormal reverse pivot shift test was associated with injury to the fibular col lateral ligament ( P = 0.01 ) , popliteal components ( P = 0.01 ) , and midthird lateral capsular ligament ( P = 0.02 ) . An abnormal posterolateral external-rotation test  at 30 ° of flexion was associated with injury to the fibular collateral ligament ( P = 0.0001 ) and lateral gastrocne mius tendon ( P = 0.01 ) . An abnormal adduction test  at 30 ° of  flex 
    Output:
    
The diagnostic accuracy of stress radiography  including the sensitivity , specificity , and positive and negative predictive values varied considerably depending on the technique and choice of displacement or gapping threshold .
Excellent reliability was reported for the diagnosis of anterior cruciate ligament , posterior cruciate ligament , varus , and valgus knee injuries .
Inconsistencies were found across studies regarding the efficacy of  stress radiography  compared with other diagnostic modalities .
Conclusions Based on the multitude of stress techniques reported , varying levels of diagnostic accuracy , and inconsistencies regarding comparative efficacy of stress radiography to other diagnostic modalities , we are not able to make specific recommendations with regard to the best stress radiography technique for the diagnosis of knee ligament injuries .