The Knee 16 (2009) 251–255

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The Knee

Stress radiography and posterior pathological laxity of knee: Comparison betweentwo different techniques

Raffaele Garofalo a,b,⁎, Gregory C. Fanelli c, Alec Cikes b, Daniel N’Dele b, Cyril Kombot b,Pier Paolo Mariani d, Elyazid Mouhsine b

a Orthopaedic and Traumatology Unit, F. Miulli Hospital, Acquaviva delle fonti, Bari, Italyb Department of Musculoskeletal Medicine, University Hospital, University of Lausanne, Switzerlandc Geisinger Medical Center, Danville, PA, USAd University of Motor Science, Rome, Italy

⁎ Corresponding author. Private address: Via PadovaBa, Italy

E-mail address: raffaelegarofalo@gmail.com (R. Garo

0968-0160/$ – see front matter © 2008 Elsevier B.V. Adoi:10.1016/j.knee.2008.12.004

a b s t r a c t

a r t i c l e i n f o

Article history:

Stress radiographs have bee Received 4 October 2007Received in revised form 22 November 2008Accepted 1 December 2008

Keywords:Kneeling viewTelos stressPosterior cruciate ligamentStress radiography

n recommended in order to obtain a better objective quantification of abnormalcompartment knee motion. This tool has showed to be superior in quantifying a posterior cruciate ligament(PCL) lesion compared to clinical or arthrometer evaluation. Different radiographic techniques have beendescribed in literature to quantify posterior pathological laxity. In this study we evaluated the total amount ofposterior displacement (PTD) and side to side difference (SSD), before and after surgical reconstruction ofPCL or PCL and posterolateral complex (PLC), using two different stress radiography techniques (Telos stressand kneeling view). Twenty patients were included in this study. We found a statistical significant differenceabout both total PTD and SSD among the two techniques preoperatively and at follow-up, with greatestvalues occurring using the kneeling view. Although stress radiographies has been introduced to allow anobjective quantification of laxity in ligamentous injured knee, we believe that further studies on a largenumbers of subjects are required to define the relationship between PTD values, measured with stress kneeradiography, particularly using kneeling view, and ligamentous knee injury, in order to obtain a real usefultool in the decision making process, as well as to evaluate the outcome after ligamentous surgery.

© 2008 Elsevier B.V. All rights reserved.

1. Introduction

The reported incidence of PCL (Posterior Cruciate Ligament)injuries has increased in the recent years and is variable from 1% to40% of acute knee injuries. This variation is dependent upon thepatient population reported, and is approximately 3% in the generalpopulation and 38% in reports from regional trauma centre [1].Despite to numerous clinical tests described to diagnose PCL andassociated ligamentous injuries, diagnosis is often missed at initialevaluation [2,3]; in fact, clinical examination can be highly subjectiveto establish posterior drawer degree and moreover associate rota-tional instability, particularly posterolateral corner (PLC) injuries.Additionally, distinguishing between partial and complete PCL injurieswith or without associated peripheral ligamentous injuries can bedifficult when using MRI, particularly in a chronic situation [4].

Arthrometers, such as KT 1000 (Medmetric, Arthrometer USA) hasbeen developed to overcome the subjectivity of clinical examination,and to quantify pathological sagittal knee translation. However,

13-70029 Santeramo in Colle-

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arthrometer measurements, although reliable for measuring anteriorpathological translation in the ACL (Anterior Cruciate Ligament)deficient knee, has showed to be less precise to measure posteriorpathological translation in PCL deficient knees [5].

In order to allow a better objective quantification of abnormalcompartment knee motion, stress radiographs have been recom-mended. This tool has showed to be superior in quantifying posteriortranslation compared to clinical or arthrometer evaluation [6–8].Different radiographic techniques have been described in literature toquantify posterior pathological laxity [2,6,9–11].

To our knowledge, a very small number of studies have showedthat measurements using these techniques can reveal different valueswhen evaluating the same patient [7,12]. Moreover, a limited numberof studies have evaluated results of PCL reconstruction using stressradiographs. The latter point is very important for two reasons: first,the difference between partial and complete rupture of PCL, betweenisolated PCL or associated PCL/PLC injury is based on a few mm(millimetres) of difference between the translation of two knees.Second, when considering some knee ligament rating scales, such asInternational Knee Documentation Committee (IKDC) [13], Hospitalfor Special Surgery (HSS) score [14], these scales are depending on themeasurement of the side to side difference (SSD). The purpose of this

Fig. 2. Photograph showing positioning used to perform kneeling stress view. The X-raycassette is between the legs.

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study is to report the results, in terms of total amount of posteriorlaxity and SSD, before and after isolated surgical reconstruction of PCL,or PCL and PLC, using two different stress radiograph techniques.

Our hypothesis is that the two different techniques show similarvalues in term of PTD (posterior tibial translation) that can helpsurgeons in the decision making concerning isolated PCL and/orcombined reconstructive surgery.

2. Materials and methods

Between October 2002 and September 2004, 20 consecutivepatients underwent a clinical observation for chronic isolated PCL orassociated PCL/PLC injury. There were 16 men and four women. Themean age was 26.4 years (range 17–43). The mean interval betweeninjury and evaluation was 5.2+/−3.5 months.

Mechanisms of injury included motor vehicle accidents in 13patients, and sports injuries in seven patients; particularly contacttrauma in five patients. In the other two cases, the injury occurredwith a fall to the ground. Six of 13 patients had associated fractures inthe same limb of the injured knee, which were previously treated andhealed without any angular deformity at the time of clinicalevaluation. No patient underwent previous knee surgery, and therewas no controlateral injury.

Physical examination was performed in order to diagnose PCLinjury and associated knee rotational instability. Posterior drawerand step-off test were carried out and compared with controlateralinjured knee. External rotation thigh-foot angle test (dial test) inprone position, posteromedial and posterolateral drawer testswere performed to evaluate associated peripheral ligamentouslesions. After clinical examination, 16 patients had an isolatedinjury, and four patients had an associated PCL and PLC disruption.Objective evaluation and quantification of pathological PTD was

Fig. 1. Photograph showing positioning used to perform Telos stress view. The patient ison a supine decubitus on the X-ray table.

carried-out using two different techniques of lateral stress radio-graph: Telos stress radiograph [11] and kneeling radiograph [9],taken from medial to lateral using a standard tube to cassettedistance of 1.15 m.

3. Telos stress radiograph

Posterior stress radiographs with the telos GA II device (Telos,Weterstad, Germany) were taken with the knee in 90° of flexion andin neutral rotation. Patient was in a lateral decubitus positionwith theknee on the table (Fig. 1), a 15 kg force was applied anteriorly at thelevel of the tibial tubercle.

4. Kneeling radiograph

Kneeling views were also taken with the knee positioned in 90° offlexion. Patients kneeled on a firm well padded bench supporting thelower leg up to the tibial tubercle whether, the patella and the femoralcondyles remained unsupported. The hands of the patients wereplaced on a metallic bar for a better comfort. The x-ray cassette wasplaced between the legs (Fig. 2). The position of the patient wasswitched in order to perform x-rays of both knees, without movingthe tube of the x-ray machine.

All the radiographs were done by one experienced orthopaedicradiologic technician. An elapsed time of 10 min between the tworadiographic techniques was observed.

Measurements of the radiographs were carried out by a singleorthopaedic surgeon according to bony landmarks described byJacobsen [6] and Staubli [15]. To perform the measurements first aline was traced across the tibial plateau, then two perpendicularlines were traced passing through the midpoint between the mostposterior edges of the medial and lateral condyles and the tibial

Fig. 3. X ray of preoperative Bartlett view with knee flexed at approximately 90°showing the drawing lines to measure the posterior translation. Yellow Lines: Contoursof Femoral condyles and tibial plateaux. Red Lines: Traced parallel to posterior tibialcortex passing through the midpoint between the most posterior edges of the medialand lateral condyles and tibial plateaux. (For interpretation of the references to colourin this figure legend, the reader is referred to the web version of this article.)

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plateaux, respectively, parallel to the posterior tibial cortex. Thenwe measured the degree of posterior tibial displacement (PTD) asthe distance in mm between the two lines (Fig. 3). We did notmeasure medial and lateral displacement values separately. ThePTD was expressed as isolated values for each injured knee, andalso as SSD.

Patients were operated on using PCL one single bundle grafttranstibial and single or double bundle grafts femoral reconstruction.In four cases a PLC reconstruction was associated.

At minimum of 1-year follow-up time for both stress radiographswas observed using the same modalities.

Fig. 4. Bar chart showing the density around the measured preoparative PTD

5. Statistical analysis

A paired Student t tests was used at a significance level of 0.05to compare the values obtained from the two different stress-x-ray techniques at preoperative and postoperative time.

6. Results

All preoperative stress radiographs independently from thetechniques, showed an increased PTD more than 10 mm in theinjured knee (Fig. 4).

Themean value of preoperative PTD in the injured knee using Telosstress radiographs was 14.8 mm (range 13.7–15.9 mm) SD 2.4. Themean value using kneeling views was 18.1 mm (range 17.0–19.1 mm)SD 2.3 (Table 1). We found a statistical very significant difference forthis total PTD among the two techniques (p=0.0001). Concerning thepre-operative SSD, we found a mean SSD of 11.9 mm (range 11.1–12.8 mm) SD 1.8, and 15.3 mm (range 14.6–16.0 mm) SD 1.4,respectively for Telos stress and kneeling view radiographs. Alsoconcerning these values, there was a statistical significant differenceon the amount of PTD (p=0.0001) and the greatest SSD differenceoccurred in kneeling views (Table 2).

At follow-up, in the reconstructed knee, a significant reduction ofthe posterior translation was observed with both techniques (Fig. 5).We found amean PTD of 8.1mm (range 6.8–9.4mm) SD 2.8with Telosstress radiographs, and a mean PTD of 11.6 (range 10.4–12.7) SD 2.5with kneeling views in reconstructed knees (Table 1). For thesevalues, we also found a statistical significant difference (p=0.0001).Finally, concerning the SSD, the mean calculated values were 5.4 mm(range 4.2–6.6 mm) SD 2.4, and 8.1 mm (range 7.0–9.2 mm) SD 2.4respectively for Telos and kneeling views (Table 2). These valuesshowed a statistical significant difference (p=0.0001).

7. Discussion

The main findings of this study performed on a consecutive seriesof 20 patients suffering a complete isolated PCL or associated PCL/PLCinjury was a significant difference in PTD among telos and kneelingstress radiographs, at preoperative and post-operative follow-up time,with the largest translation observed with the kneeling stresstechnique. The hypothesis of this study was not proven. Whenanalyzing the results for each patient enrolled in this study, we

values in 20 patients, using the Telos and Bartlett stress view techniques.

Table 2Mean value and comparative assessment of side to side difference for both stress viewtechniques with variation in SSD between native and reconstructed knee.

Preop. SDDmean value(95% Cl)

ΔBartlett–Telos forpreop. SDD(p-value)

Postop. SDDmean value(95% Cl)

ΔBartlett–Telos forpostop. SDD(p-value)

ΔPreop.–postop. SDD(p-value)

Telos 11.9 (111–12.8) 3.3(b0.0001)

5.4 (4.2–6.6) 2.7(b0.0001)

6.5 (b0.0001)Barlett 15.3 (14.6–16.0) 8.1 (7.0–9.2) 7.1 (b0.0001)

All figures are given in mm.

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observed neither at pre-operative time, nor at follow-up, an increasedPTD of at least 3 mm greater in kneeling view compared toTelos stressradiographs. Additionally, this difference of PTD was observed in themeasurement of SSD as well.

To our knowledge, no study has previously been conducted toassess pre and pre-operative difference between these two differenttechniques of stress radiographs in a group of patients with isolatedcomplete PCL or associated PCL/PLC chronic injury.

Different clinical tests have been proposed in the literature todetect a PCL injury, or to detect associated peripheral ligamentousinjuries requiring surgical reconstruction. In our study, surgicaldecision making was based on findings revealed by different testsperformed during clinical examination. However, limitations ofclinical findings in evaluating and quantifying the grade of PCL lesionand associated peripheral injuries arewell recognized in literature [2].Stress radiograph techniques have been introduced with the idea toquantify objectively the mm of pathological tibial translation in aninjured knee. In previous reports, these techniques showed a highaccuracy in diagnosing knee injuries, superior to clinical examinationand instrumented laxity measurement [3,16]. Staubli et al. [17] refinedstress radiographic techniques with the use of Telos device, andconcluded that posterior stress radiography is an accurate method tomeasure anterior–posterior motion of the knee. Additionally, a recentstudy demonstrated that stress radiographs using a Telos device withthe knee at 90° of flexion exhibited a useful reliability in theevaluation of PTD in knees presenting PCL lesions [8].

Furthermore, posterior stress radiographs have been proposed toevaluate not only the degree of PCL injury, but also to differentiateisolated PCL lesion from more complex multi-ligamentary injuries.This is very important to help surgeons in their decision making. Forinstance, it's well accepted in literature that kneeswith a PTD less than8 mm on stress radiographs have a partial PCL tear and should betreated conservatively [16]. On the other hand, when a PTD of 10 mmor more is measured, this value should indicate a complete PCLrupture, and a surgical management should be discussed. When theSSD shows a difference equal or more than 12 mm, an associated PCL/PLC injury could be considered [18]. All these values have beenreferred to Telos stress radiographs and by evaluating them, we canunderstand that a small difference of a few mm can modify thedecision making, as well as surgical options.

Like other authors, we also found that using different stressradiograph techniques, the results obtained can be different [7,12].Unlike the study of Jung et al. [12], we found a significant difference inmm of PTD between Telos stress at 90° and kneeling views. Thisdifferencewas present at preoperative time and also at follow-up aftersurgical reconstruction. The reason for this difference between ourreported results and the Jung et al. study [12] is unclear with the dataat hand. However, we can attempt to explain the different valuesfound in our study between the two stress radiographic techniques.

In our opinion, if we analyze the rationale of the two techniques,one explanation of the difference between themeasured values of PTDseems to be logical. While performing Telos stress X-ray views, a 150 Nposterior load is applied to the anterior aspect of the tibia [15],whereas during kneeling stress views, the applied anterior force hasbeen calculated to be approximately 250–300 N in a 70 kg-man [19];

Table 1Mean value and comparative assessment of posterior translation for both stress viewtechniques with difference in PTD between native and reconstructed knee.

Preop. PTDmean value(95% Cl)

ΔBartlett–Telos forpreop. PTD(p-value)

Postop. PTDmean value(95% Cl)

ΔBartlett–Telos forpostop. PTD(p-value)

Δpreop.–postop. PTD(p-value)

Telos 14.8 (13.7–15.9) 3.2(b0.0001)

8.1 (6.8–9.4) 3.4(b0.0001)

6.7 (b0.0001)Barlett 18.1 (17.0–19.1) 11.6 (10.4–12.7) 6.5 (b0.0001)

All figures are qiven in mm.

We can then suppose that the kneeling position allows a betterquadriceps muscle relaxation, and an increased PTD.

Another important finding of the present study is that not only theabsolute values of PTD of the injured knee itself was different in thetwo techniques, but the SSD values were significantly different as well,showing that the kneeling views allow a greater PTD in a knee with aPCL or PCL/PLC injury, indicating that this technique can be probablymore sensitive to reveal this pattern of injuries.

According to these considerations, the crucial point is to under-stand which of the two techniques should be used, and what valuesshould be taken in account in order to differentiate a partial from acomplete isolated PCL or PCL/PLC associated injury. Considering thelimitations of clinical examination and other imaging techniques, suchas magnetic resonance imaging (MRI), to assess this type of lesions,and the under treatment of these associated ligament injuries, are themost important causes of PCL reconstruction failure [20]. In a pilotstudy, Donell et al. [21] showed that performing the MRI scan with asplint stressing the knee can be useful to enhance the accuracy indiagnosing the grade of cruciate ligament tear. However, pathologicalparameters observed onMRI images in this study need to be evaluatedin a more large series of patients and confirmed arthroscopically.

There are some limitations in our study. First, the degree of painwhen performing the two different techniques was not evaluate. Thispoint is very important; patient's guarding during radiographicevaluation may produce quadriceps muscle activity and may reducePTD. Although no significant difference in experienced pain betweenthe two radiographic techniques has been previously reported [12],although our technique in performing kneeling views was a littledifferent, particularly in the patients positioning. We suppose that thepositioning used in our study, can allow a better relaxation of thepatient, and this could explain the greatest PTD value obtained withthis technique. Another limitation in our study can be related to thenumber of patients enrolled. Although this point can be justify by therarity of these types of injuries. We excluded all the knees with anassociated ACL injury. Surgical decision making was based on theclinical examination performed by the surgeon. Stress radiographswere used just to confirm the presence of a pathological PTD requiringsurgery. We did not consider any relationship between the degree ofPTD and the type of knee ligamentous injury. Thus no conclusion canbe made on that matter. Furthermore, all the radiographic measure-ments were performed by a single orthopaedic surgeon. Although weare sure that themethod usedwas always the same, we don't have anydata on intra or inter-observer variability using the two differentradiological techniques.

In summary, our study revealed that in presence of isolated PCL orassociated PCL/PLC injuries, values of PTD obtained using Telos andkneeling stress radiographs revealed an extremely significant differ-ence. Although, stress radiographs have been proposed to assess anobjective quantification of the laxity in the injured knee. In order toassess if this technique is more sensitive tool to evaluate a pathologicalPTD, especially in cases of combined lesions, or if it just overestimatesa posterior capsule-ligamentous knee lesion because of a greater forceof translation applied on the knee; further studies are necessary todefine the relationship between PTD values measured with stress

Fig. 5. Bar chart showing the repartition around the measured PTD values in the reconstructed knee of the 20 patients, using the two different stress view techniques.

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knee radiographs, particularly with kneeling views, and ligamentousknee injury.

8. Conflict of Interest

No conflict of interest.

References

[1] Fanelli GC, Edson CJ. PCL injuries in trauma patients, part II. Arthroscopy1995;11:526–9.

[2] Chassaing VDF, Touzard R, Ceccaldi JP, Miremad C, Lemaire M. Etude radiologiquedu LCP a 90° of flexion. Rev Chir Orthop Repar Appar Mot 1995;81(Suppl 2):35–8.

[3] Rubinstein Jr RA, Shelbourne KD, McCarroll JR, et al. The accuracy of the clinicalexamination in the setting of posterior cruciate ligament injuries. Am J Sports Med1994;22:550–7.

[4] Patten RM, Richardson ML, Zink-Brody G, Rolfe BA. Complete vs partial-thicknesstears of the posterior cruciate ligament: MR findings. J Comput Assist Tomogr1994;18(5):793–9.

[5] Huber FE, Irrgang JJ, Harner C, Lephart S. Intratester and intertester reliability ofthe KT-1000 arthrometer in the assessment of posterior laxity of the knee. Am JSports Med 1997;25(4):479–85.

[6] Jacobsen K. Stress radiographical measurement of anterior–posterior, medial andlateral stability of the knee joint. Acta Orthop Scand 1976;47:335–41.

[7] Margheritini F, Mancini L, Mauro CS, Mariani PP. Stress radiography for quantifyingposterior cruciate ligament deficiency. Arthroscopy 2003;7:706–11.

[8] Schulz MS, Russe K, Lampakis G, Strobel MJ. Reliability of stress radiography forevaluation of posterior knee laxity. Am J Sports Med 2005;4:502–6.

[9] Osti L, Bartlett J. The value of the kneeling view to evaluate the posterior kneeinstability. Presented at the International PCL Study Group meeting, Kurumba,Maldives; December, 2001.

[10] PudduGGE, Chambat P, Paulis F. The axial view in evaluating tibial translation in casesof insufficiency of the posterior cruciate ligament. Arthroscopy 2000;16:217–20.

[11] Strobel M, Stedtfeld HW. Stress roentgen study of the knee joint – an evaluation ofstatus. Unfallchirurg 1986;6:272–9.

[12] Jung TM, Reinhardt C, Scheffler SU, Weiler A. Stress radiography to measureposterior cruciate ligament insufficiency: a comparison offive different techniques.Knee Surg Sports Traumatol Arthrosc 2006;14(11):1116–21 [Epub 2006 Jun 24].

[13] Anderson AF. Rating scales. In: Fu FH, Harner CD, Vince KG, editors. Knee Surgery.Baltimore: Williams & Wilkins; 1994. p. 275–96.

[14] Windsor RE, Insall JN, Warren RF, et al. The hospital for Special Surgery kneeligament rating form. Am J Knee Surg 1988:1140–5.

[15] Staubli HU, Noesberger B, Jacob RP. Stress radiography of the knee. Cruciateligament function studied in 138patients. ActaOrthop Scand Suppl 1992;249:1–27.

[16] Hewett TE, Noyes FR, Lee MD. Diagnosis of complete and partial posterior cruciateligament ruptures: stress radiography compared with KT-1000 arthrometer andposterior drawer testing. Am J Sports Med 1997;25:648–55.

[17] Staubli HU, Jacob RP. Posterior instability of the knee near extension: a clinical andstress radiography analysis of acute injuries of the posterior cruciate ligament. JBone Joint Surg Br 1990;72:225–30.

[18] StrobelM,Weiler A. Management of the posterior cruciate ligament deficient knee.Tech Orthop 2001;16(2):167–94.

[19] Louisia S, Siebold R, Canty J, Bartlett RJ. Assessment of posterior stability in totalknee replacement by stress radiographs. Prospective comparison of two differenttypes of mobile bearing implants. Knee Surg Sports Traumatol Arthrosc2005;13:476–82.

[20] Noyes FR, Barber-Westin SD. Posterior cruciate ligament revision reconstruction,part 1: causes of surgical failure in 52 consecutive operations. Am J Sports MedMay 2005;33(5):646–54 [Epub 2005 Feb 16].

[21] Donell ST, Marshall TJ, Darrah C, Shepstone L. Cruciate ligament assessment in MRIscans: a pilot study of a static drawer technique. The Knee 2006;13:137–44.