Lumbar radiographs in anteroposterior (AP), lateral, and oblique

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1 Diagn Interv Radiol 200; 15:1 1 Turkish Soiety of Radiology 200 MUSCULOSKELETAL IMAGING ORIGINAL ARTICLE Postoperative lumar spine: modified radiographi projetions for detetion of one defets in adavers Lee Ren Yeh, Julio Urrutia, David Sartoris, Steven Garfin, Nittaya Lektrakul, Donald Resnik PURPOSE Speial radiographi projetions were evaluated in two adaveri speimens for depiting postoperative hanges after five different lower lumar surgial proedures. Availale literature onerning speial radiographi projetions of the lumar spine is limited. The ojetive of this study was to estalish a speial radiographi projetion that is useful for depiting postoperative hanges after lumar surgial proedures. MATERIALS AND METHODS Five different proedures were performed on two adaveri lumar spines: laminotomy, total laminetomy, foraminotomy, surgial reation of pars interartiularis defet, and partial faetetomy. A series of radiographs, inluding routine views and ominations of various oliquity and ephalad angulation, were otained preoperatively and after eah operation. Film analysis was done using a four-point rating system to doument the degree of visualization of the postsurgial one defet at eah stage of surgery at eah lumar segment. The est projetions were determined y summation of the rating sores of the three lumar segments. The sores of eah projetion in different proedures were also summed to determine the est view for linial use. RESULTS The laminotomy defets were more ovious on the shallow-oliquity and low-angulation radiographs. The postoperative hanges of total laminetomy were almost equally identified on the AP and lateral views and most of the ompound views. The one hanges of foraminotomy were est identified on the 45 routine view. The and ompound views were est for depiting a postoperative pars defet. None of the projetions delineated the one hanges of partial faetetomy. The ompound view had the highest summation of rating sores of the five surgial proedures. CONCLUSION The results of this study suggest that the ompound view ould e useful for the assessment of the postoperative lumar spine. Further verifiation of its value requires a large linial study. Key words: laminetomy lumar verterae diagnosti imaging From the Department of Radiology (L.R.Y.), E-Da Hospital and I-Shou University, Kaohsiung, Taiwan, Provine of China; the Departments of Radiology (D.S., N.L., D.R.), and Orthopedis (S.G.), University of California, San Diego, CA, USA; and the Department of Orthopedis (J.U. jurrutia@l.l), Pontifiia Universidad Catolia de Chile, Santiago, Chile. Reeived 1 Deemer 2007; revision requested 2 January 200; revision reeived 24 January 200; aepted 24 January 200. Lumar radiographs in anteroposterior (AP), lateral, and olique projetions are frequently otained in the evaluation of the lumar spine. AP and lateral views generally are used in the radiographi survey in patients with lumar prolems; 45 olique projetions are often used to demonstrate a defet of the pars interartiularis, whih may e diffiult to see in the AP and lateral views. However, these routine views are of limited value when applied to the postoperative spine, as they may fail to reveal the one hanges resulting from various deompressive spinal proedures, suh as laminotomy, foraminotomy, and partial faetetomy. The purpose of this study was to estalish a speial radiographi projetion to depit postoperative hanges after various lumar surgial proedures. Materials and methods Initially, 45 radiographs in various projetions were otained on a adaveri lumar spine speimen using ominations of different spinal oliquity (from AP to 60 olique, with inrements of 15 ) and tue angulation (from 60 audad to 60 ephalad, with inrements of 15 ), with the eam entered at the fourth lumar vertera. Projetions with etter en fae depition of the laminae and the faet joints of the lower lumar segments were determined and used for susequent parts of the study. Five different proedures were performed y an orthopedi spine surgeon on two adaveri lumar spines. A series of radiographs were taken preoperatively and after eah operation. The first proedure was a laminotomy of the third, fourth, and fifth lumar verterae (L, L4, and L5), a proedure frequently performed during lumar dis surgery. The seond proedure inluded a partial laminetomy of L and omplete L4 and L5 laminetomies in the first speimen. Complete laminetomies at all three lower lumar segments were performed in the seond speimen. The third proedure was foraminotomy, whih was performed ilaterally over the L, L4, and L5 nerve roots in the first speimen, and on the right side of the same nerves of the seond speimen. This proedure was performed y partial removal of the medial aspet of the pedile and zygapophyseal proess along the ourse of the nerve root. In the fourth stage, a defet or frature of the pars interartiularis was reated on one side at eah lumar segment, a ondition that ould our during or after an extensive deompressive proedure. The final proedure omponent was partial faetetomy of one side of L L4, L4 L5, and L5 S1. Based on the analysis of the preoperative radiographs in the first part of this study, 22 projetions were otained preoperatively and after eah stage of surgery in the first speimen, inluding 4 routine views (AP, lateral, and ilateral 45 olique views) and 1 ompound views (ominations of 15, 0, or 45 of oliquity, oth right and left anterior, with 15, 1

2 Figure 1. a. Laminotomy. Left anterior olique ompound X-ray view (a). Cortial irregularities were identified at the L 4, L4 5, and L5 S1 along the superior and inferior orders of the right sides of the laminae. The surgery performed on L5 S1 was limited, and minimal ortial defets were identified. Two larger ortial defets are well demonstrated (arrows). The laminar ortex at the L2 was left intat for omparison. The defets of the left side of the laminae were also well demonstrated on the ontralateral ompound view (not shown). Anteroposterior (AP) X-ray view of the same speimen (). The laminotomy defets are more sutle on the AP view (arrows). Routine 45 left anterior olique X-ray view (). The defets are muh more diffiult to identify. 0, or 45 of ephalad angulation). In the seond speimen, eight ompound views (ominations of ilateral 15 and 0 oliquity with 15 and 0 ephalad angulation) and the four routine views were otained after eah stage. Analysis of the films was done y two radiologists in onsensus, using a four-point rating system to doument the degree of visualization of the postsurgial one defet after eah stage of surgery at eah lumar segment (, exellent visualization; 2, suoptimal visualization; 1, diffiult visualization; 0, nonvisualization). The est projetions for eah stage of the surgery were determined y summation of the rating sores of the three lumar segments. The sores of eah projetion in different stages of surgery were also summed to determine the est view for linial use. Eah projetion was given an areviated title ased on two figures: the first represented the degree of spinal oliquity and the seond represented the degree of ranial angulation of the x-ray eam (e.g., projetion with 0 of oliquity and 15 of ranial angulation was areviated as ompound view). Results The projetions with highest rating sores for eah proedure are summarized in Tale 1. The laminotomy defets were more ovious on the shallow-oliquity and low-angulation radiographs (, 15-0, and 0-15 ompound views). These defets were suspeted on the AP view after Tale 1. Optimal radiographi views for eah stage of surgery Stage 1 (laminotomy) 15-0 Stage 2 (total or partial laminetomy) AP-lateral Stage (foraminotomy) routine 45-0 Stage 4 (surgially reated pars frature or defet) areful inspetion, ut were more sutle than on the aove three views. The routine 45 views did not allow good visualization of the laminotomy defets (Fig. 1). Speimen 1 Speimen 2 Projetion Sore a Projetion Sore a AP-lateral 45 routine Stage 5 (partial faetetomy) None a Summation of the rating sores on L, L4, and L5 (for stage 1, 2, and 4 operations) or on L 4, L4 5, and L5 S1 (for stage and 5 operations). AP, anteroposterior Septemer 200 Diagnosti and Interventional Radiology Yeh et al.

3 d e f Figure 2. a f. Total laminetomies with right foraminotomies. Sagittal view of the speimen (a). Note the one defets reated during foraminotomies (interrupted irles), whih were performed y partial removal of the one along the ourse of the nerve root. Anteroposterior (AP) X-ray view (). The one hanges of total laminetomy are learly demonstrated, ut those of foraminotomies are not identified. Routine 45 right anterior olique (RAO) X-ray view (). Routine 45 left anterior olique (LAO) view (d). The one hanges of foraminotomies are identified in (), with loss of ortial lines of the faets (thin arrows) and thinning of the right pars interartiularis (open arrows). Thikness of the normal left pars interartiularis is shown in (d). RAO X-ray view (e). The one hanges (thin arrows) with thinning of the right pars interartiularis (open arrows) are also identified. LAO X-ray view (f). The ortex of the left neural foramen is intat and the thiknesses of left pars interartiularis are normal. The postoperative hanges of total laminetomy were well identified on the AP and lateral views. Although the ompound views also revealed the one hanges, none provided additional information eyond that derived from the AP and lateral views. In the partial L laminetomy, a notieale differene was found etween the results derived from views with ephalad angulation greater than 0 and those of views otained with lesser angulation. The former provided poorer depition of the laminae eause of overlap with L2. Foraminotomies were diffiult to identify on the radiographs of the first speimen. The hanges were not seen at L 4 and L5 S1 and only partially identifiale at L4 5, ut only on three views: 45-15, 45 routine, and In the seond speimen, the one hanges were seen more easily than in the first speimen, and were est identified on the 45 routine view, followed y and 0-0 ompound views. Other views (inluding the AP view) did not allow lear delineation of the one hanges (Fig. 2). The and ompound views were est for depiting a postoperative pars defet. However, most of the other ompound views (e.g., Volume 15 Issue Postoperative lumar spine: modified radiographi projetions 15

4 d Figure. a d. Pars interartiularis defets or fratures. right anterior olique (RAO) X-ray view (a). left anterior olique (LAO) X-ray view (). Routine 45 RAO X-ray view (). Routine 45 LAO X-ray view (d). The L pars frature is well identified on oth views and routine 45 views (upper arrow), ut the L4 pars frature (middle arrow) is etter demonstrated on view than on routine 45 views. Thinning of L5 pars (lower arrow) is identified in (a), (), and (), ut is less distint in (d). The open arrow indiates a normal pars interartiularis viewed on different olique projetions (a, ). 45-0, routine 45,, 15-0, and 0-0 ) were also useful for demonstrating the defets, exept those views with extreme angulation (45 ). The routine 45 olique view was of moderate value in its aility to allow identifiation of the pars interartiularis defets (Figs., 4). On the radiographs otained after partial faetetomy, most of the defets were not evident exept at the L5 S1 level of the seond speimen. This defet was equally demonstrated with the, 15-0,, and 0-0 ompound views, and slightly less well defined on the 45 routine view. Bone hanges at other levels and hanges in the other speimen were not delineated y routine and ompound views (Fig. 4). The summations of rating sores from stage 1 to stage 5 of surgery for eah radiographi projetion are listed in Tale 2. The ompound view had the highest sore in oth speimens. Disussion It is not unommon in linial pratie for a radiologist or spine surgeon to enounter films of a patient with a prior history of lumar surgery ut with no details availale aout the proedure that had een performed. Although CT san is the most sensitive and speifi study for postoperative evaluation of a postoperative spine, plain radiographs are usually the first study performed for evaluation of patients, inluding those who have undergone deompressive surgery. Routine AP and lateral radiographs may reveal the postoperative hanges after total or partial laminetomy, ut these radiographs are usually inadequate in the delineation of the one defets after laminotomy and proedures involving the neural foramen, suh as foraminotomy and faetetomy. The routine 45 olique view also is not informative in this regard. Many physiians have aandoned its routine use in the postoperative evaluation of the lumar spine. Availale literature onerning speial radiographi projetions of the lumar spine is limited. Ael et al. (1, 2) have emphasized an AP view with Tale 2. Summation of the total rating sores of eah radiographi view Speimen 1 Speimen 2 AP-lateral 1 15 Routine 45 olique o 1 NA NA NA NA NA NA, not availale; AP, anteroposterior. 16 Septemer 200 Diagnosti and Interventional Radiology Yeh et al.

5 d Figure 4. a g. Partial faetetomy and pars defet or frature. The partial faetetomies were performed on the left side and the pars lesions were reated on the right side. Sagittal view of the speimen (a) with slight oliquity showing the postoperative hange of partial faetetomy, whih was done y removing ligamentum flavum, joint apsule, and anteromedial aspet of the faet joint that faed the spinal anal (arrows). Axial CT san () of the partial faetetomy in the other speimen. The anteromedial aspet of the faet joint has een removed. Note the loss of the ortial line on the anteromedial aspet of the faet joint (arrows). True lateral X-ray view (). No ovious one hange an e identified exept asene of the spinous proess of L, L4, and L5, whih were postoperative defets after total laminetomies. Anteroposterior X-ray view (d). The defets of the right pars interartiularis an e identified at L and L4 (arrows), ut not at L5. left anterior olique (LAO) X-ray view (e). right anterior olique (RAO) X-ray view (f). The pars fratures (arrows) at L and L4 are slightly etter seen in (f) than in (e), whereas the defet at L5 is etter identified in (e) than in (f). The interrupted irles (e, f) indiate the faet joints. No definite one hange an e identified exept a possile luent defet at the level of L5 S1 (arrowhead, e) on the RAO view (ompare with Fig. 2f). Routine 45 RAO X-ray view (g). The pars fratures (arrows) at L and L4 are also well demonstrated, ut not as well as in (f), espeially at L4. The defet of the pars interartiularis of L5 is not identified. The one hanges of the faet joints are not demonstrated in this view. e f g Volume 15 Issue Postoperative lumar spine: modified radiographi projetions 17

6 Figure 5. Shemati representation of the suggested ompound view for routine use. The patient is positioned 0 oliquely to the tale and the entral eam of the X-ray is direted at L4 and angulated 15 ephalad. Both olique views should e taken. 45 audal angulation as valuale in revealing the posterior elements of the lumar spine. Lison and Bloom () suggested using a 0 ranially angulated AP view to detet defets of the pars interartiularis. Amato et al. (4) ompared the frequeny of deteting isthmus defets on AP, lateral, 45 olique, 0 ephalad angled AP, and ollimated lateral views, and found the ollimated lateral view to e most sensitive. Saifuddin et al. (5), after studying spondylolyti lesions, suggested that CT sans should e used instead of olique radiography for the assessment of spondylosis, as only 2% of defets were oriented within 15 of the 45 lateral olique plane. Based on our experiene derived from our initial speimen, the audad angulated views rendered the laminae foreshortened and narrowed, suh that a small surgially reated laminar defet may e osured. In ontrast, on ephalad angulated views the laminae are seen more en fae, thus allowing etter visualization of small laminar defets. In our speimen, the one defets following laminotomy were visualized only partially on the standard AP and 45 olique views. They were est visualized on the and 15-0 ompound views, followed y the ompound view. The finding that the ompound views with 15 of oliquity allow etter depition of the laminae than those with 0 of oliquity orrelates with the fat that the laminae 1 Septemer 200 Diagnosti and Interventional Radiology of the lumar spine are oriented approximately 15 oliquely with regard to the oronal plane of the ody. In this study the one hanges from foraminotomies were etter identified in the seond speimen, in whih a more extensive operation had een performed. They were est visualized y the routine 45 olique views, followed y and 0-0 ompound views, ut they were ompletely invisile on the routine AP and lateral views. At the fourth stage of surgery, a defet or frature of the pars interartiularis was iatrogenially reated to simulate one ompliation of a deompressive operation; suh fratures may our during or after the operation if the pars interartiularis was weakened y the osseous removal of the posterior elements. In oth speimens, the plane of the surgially reated pars frature differed from that of an isthmi spondylolysis. Speifially, a rightsided pars defet ourring in isthmi spondylolysis is usually seen more easily on the right anterior olique view, whereas a surgially reated one is delineated more learly on the left anterior olique view. Therefore, oth olique views should e otained, sine they may omplement one another. In this study, the ompound view was etter than the routine 45 olique view for identifiation of the surgially reated pars frature. The AP and lateral views were not useful for this purpose. Most of the one hanges following partial faetetomy were not evident in the routine and ompound views. This proaly relates to the fat that the portion of one removed was oriented en fae to the X-ray eam rather than in profile (Fig. 4). We have tested a 70 olique view, whih might show the surgial defet in profile. However, the results of this view also were poor eause of superimposition of the ontralateral faet joint. Of all the ompound and routine views, the view had the highest total sore in oth speimens, and thus is reommended as the est view for the general evaluation of the postoperative lumar spine (Fig. 5). This view was the est for demonstration of osseous hanges related to total laminetomies and pars interartiularis defets, and was seond est for delineation of suh hanges related to laminotomy and foraminotomy. In our studies, the entral eam used for this view was loalized to L4, whih is relatively lower than that employed for routine AP and olique views. We hose this lower level eause most lumar operations are performed at the lower segments of the lumar spine. Oviously, fousing the enter eam on the region of primary onern helps optimize the radiographi examination. Theoretially, the degree of lumar lordosis may influene the results otained with this speial view. The degree of lumar lordosis in our speimens was within normal limits; thus, 15 to 0 ranial angulation is adequate for demonstrating laminotomy and other surgial defets. In a patient with exaggerated lordosis, a ranial angulation greater than 0 may e neessary. Therefore, to ahieve the est results in a speifi patient, it may e neessary to adjust the degree of angulation ased on the degree of lumar lordosis. However, adjusting the angulation patient y patient will render this speial view less pratial for daily use. We elieve that our sreening view is suitale for most patients, and that slight adjustments of angulation generally will not e required. This study was limited y the small numer of speimens. Sujetive ias from the reading radiologist was another limitation of this study. Other limitations may relate to the fats that we did not evaluate all types of surgery or surgery at other levels, study the en- Yeh et al.

7 efits of this ompound view in patients without surgery, and assess visualization of other findings suh as degenerative dis disease and osteoarthrosis. In onlusion, the results of this adaveri study suggest that the ompound view may e useful for the assessment of the postoperative lumar spine. Further verifiation of its value requires a large linial study. Referenes 1. Ael MS, Smith GR, Allen TNK. Refinements of the anteroposterior angled audad view of the lumar spine. Skeletal Radiol 11; 7: Ael MS, Smith GR. Visualization of the lumar verterae in the anteroposterior projetion. Radiology 177; 122: Lison E, Bloom RA. Anteroposterior angulated view. A new radiographi tehnique for the evaluation of spondylolysis. Radiology1; 14: Amato M, Totty WG, Gilula LA. Spondylolysis of the lumar spine: demonstration of defets and laminal fragmentation. Radiology14; 15: Saifuddin A, White J, Tuker S, Taylor BA. Orientation of lumar pars defets: impliations for radiologial detetion and surgial management. J Bone Joint Surg Br 1; 0: Volume 15 Issue Postoperative lumar spine: modified radiographi projetions 1