Glenohumeral relationship in maximum elevation

Transcription

1 Surg Rdiol Ant (2014) 36: DOI /s y ORIGINAL ARTICLE Glenohumerl reltionship in mximum elevtion Hiroki Inui Ktsuy Nobuhr Received: 19 July 2013 / Accepted: 9 Jnury 2014 / Published online: 24 Jnury 2014 The Author(s) This rticle is published with open ccess t Springerlink.com Abstrct Purpose The purpose of this study ws to clrify rottionl reltionships between the ntomicl lndmrks of the glenohumerl joint in mximum elevtion. Methods Twenty-five helthy volunteers (20 men, 5 women; men ge, 31 yers) held the rm in mximum elevtion in n open MRI system. In ech three-dimensionlly computer-generted imge, elevtion ngle of the humerus in the plne of elevtion ws mesured, bsed on the glenoid nd the scpulr plnes. Using the equtor set on the hed surfce by the plne prllel to the humerl xis, involving the hed center nd the bicipitl groove, glenoid loction nd rottionl reltionships were investigted. Results The elevtion ngle ws 102 ± 9 in the plne 7 ± 8 to the scpulr plne, nd xil rottion ws fixed with the glenoidl long xis prllel to the equtor (within 2 ). Ech glenoid center locted on ntero- portion of the humerl hed, nd the direction from the top of the hed to its loction ws the sme s tht of the shft tilting, indicting the glenoid only trnslted without rottion fter reching the top of the hed on the equtor. Conclusions Before reching mximum elevtion, the glenohumerl joint would be locked in xil rottion. The position when the glenoid is on the top of the humerl hed with the humerl shft perpendiculr to the glenoid is considered to be essentilly the finl position of elevtion, bove which the glenohumerl joint only trnsltes without xil rottion even if the humerus is more elevted. Keywords Shoulder Glenohumerl joint Mximum elevtion Externl rottion MRI Introduction Arm elevtion is one of the most importnt functions of the shoulder in our dily lives [4, 12, 13]. Mny studies [1, 3, 5, 7, 9, 11, 14, 16, 17] pproched the topics bout rm elevtion, one [11] of which indicted tht the humerus moves towrd similr finl position t the end of rising the rm irrespective of the plne of elevtion, nd its position is one of externl rottion nd elevtion of the humerus reltive to the scpul, slightly to the plne of the scpul. However, they only mesured rottionl ngles of the glenohumerl joint nd could not clrify the reltionships between the ntomicl lndmrks of its joint. When the rm reches its position, most proximl prt of the humerus is covered with the cromion, mking it difficult to know the ntomicl position of the joint. We investigted rottionl reltionships between the ntomicl lndmrks of the glenohumerl joint in mximum elevtion. Mterils nd methods Electronic supplementry mteril The online version of this rticle (doi: /s y) contins supplementry mteril, which is vilble to uthorized users. H. Inui (*) K. Nobuhr Nobuhr Hospitl nd Institute of Biomechnics, 720 Hze, Issicho, Ttsunoshi, Hyogo , Jpn e-mil: inuhiro123@yhoo.co.jp Twenty-five volunteers (20 men, 5 women) without symptoms or history of shoulder disese were enrolled in the study. Men ge ws 29 (21 35) yers. All prticipnts provided informed consent. The mximum elevtion of the shoulder ws defined s the position in which the tips of fingers could rech highest in stnding position. A

2 756 Surg Rdiol Ant (2014) 36: Fig. 1 The rm ws plced in mximum elevtion in which the tips of fingers reched highest in stnding position. A surgicl mttress ws dopted round his upper extremity nd body to reproduce the position. b The mttress is mde of micro-blls of styrofom, which re stbilized by vcuum. c Volunteer with the mttress, lying in oblique supine position in n open MRI (Mgnetom Open, Siemens, Germny) surgicl mttress (VACUFORM; Schmidt, Grbsen, Germny) mde of micro-blls of styrofom, which could be stbilized by vcuum, ws dopted round his or her upper extremity nd body to reproduce shoulder position (Fig. 1). The mount of prontion or supintion of the forerm ws not specified. Ech prticipnt mintined the sme mximum elevtion with tht surgicl mttress, lying supine in 0.2-T MRI system (Mgnetom Open, Siemens, Munich, Germny). The shoulders were imged using three-dimensionl (3D) grdient echo (repetition time, 56 ms; echo time, 25 ms; flip ngle, 40 ) with 2-mm thickness. All imges were obtined with n 18-cm FOV nd mtrix. Imging process required n verge of 10 min. All dt were trnsferred to computer (O2; SGI, Mountin View, CA) nd 3D imge of the glenohumerl joint including the proximl prt of the humerus ws generted using computer softwre (3D-Virtuoso, Siemens). Providing instnt ccess to 3D informtion, the sme softwre llowed ntomies to be viewed from ny ngle. Antomicl lndmrks such s the glenoidl long xis, glenoid center, humerl hed center, nd humerl shft xis (Fig. 2) were defined s described below [10]. On the glenoid rim, the point just posterior to the corcoid bse ws defined s the rim nd the point just to the lterl border of the scpul ws defined s the inferior rim. The line connecting these points ws defined s the glenoidl long xis. The glenoid plne ws defined s the plne including the glenoidl long xis, nd ws prllel to the trnsverse xis connecting the nd posterior rims on cross-section t the center level of the glenoid. The scpulr plne ws defined s the plne including the glenoidl long xis nd ws perpendiculr to the glenoid plne. Two cross-sections of the humerus were obtined t 7.5 nd 15 cm from the proximl end. The center for these cross-sections of the corticl bone ws determined by fitting circle, nd the humerl xis ws defined s the line tht pssed through the center of these circles. Using the dt of Innotti et l. [8], which showed correltions between size of the glenoid nd the rdius of curvture of the humerl hed, ech humerl rdius ws clculted s follows: rdius (mm) = 24 length of glenoidl long xis/39 (where 24 is the verge hed rdius nd 39 is the verge glenoidl long xis in the popultion s mesured by Innotti et l.). The hed ws cut in plne perpendiculr to the humerl xis t the distnce of the rdius from the proximl end, nd the center determined by fitting circle of the sme rdius. This ws regrded s the center of the hed. In this plne, the bottom of the bicipitl groove ws lso plotted.

3 Surg Rdiol Ant (2014) 36: Fig. 2 Illustrtions showing the ntomicl lndmrks such s glenoidl long xis (the line between nd inferior rims), glenoidl trnsverse xis (the line between nd posterior rims), humerl hed center, nd humerl shft xis. A rim, P posterior rim, S rim, I inferior rim, r humerl rdius. The computer screen disply shows the long nd the trnsverse xes of the glenoid, the humerl shft xis, nd the humerl center. b Globl digrm set on the hed surfce with the plne including the hed center (blck dot) nd the bicipitl groove, nd the prllel plnes nlogous to ltitudes. Stright lines represent circles of ltitude nd curved broken lines represent circles of longitude. Rottion (α) is referenced to ltitude by rotting the globe to lign longitude including the midpoint (X) of the glenoidl long xis (stright broken line) with the verticl. bicipitl groove top of the hed r humerl shft xis 7.5 cm 15 cm center of the hed bicipitl groove r I P S A b glenoidl plne The slope of the humerl long xis on the glenoid ws determined by mesuring the ngle reltive to the glenoidl long xis nd nlyzing their orienttion in the trnsverse plne, reltive to the scpulr plne, in which the humerus ws elevted. Rottion of the glenohumerl joint ws visulized on the computer screen s follows. The equtor ws set on the hed surfce by the plne prllel to the humerl long xis, including the hed center nd the bicipitl groove. Prllel lines to the equtor were nlogous to ltitudes. Rottion ws referenced to ltitude by rotting the globe to lign the longitude, including the midpoint of the glenoidl long xis, with the verticl. The ngle when the glenoidl long xis becme prllel to ltitude ws defined s 0 nd vlues in externl rottion were defined s positive. To investigte loction of the glenoid center, the surfce of the humerl hed ws divided into four segments ( portion; Zone I, posterior portion; Zone II, inferior portion; Zone III, nd posterior inferior portion; Zone IV), using the equtor nd the circle of longitude crossing the top of the hed. Menwhile, the shft xis nd the center of the humerus in ech subject were projected orthogonlly to the glenoid plne to confirm the reltion between the ntomicl lndmrks. Ten different glenoids were nlyzed mesuring length vlues of the long nd the trnsverse xes by two independent investigtors to determine the inter-observer vribility. To mesure the intr-observer vribility, those vlues in 10 glenoids were mesured twice by the sme person. Angle vlues of the plne including the shft xis nd the hed center to the equtor on the hed surfce were lso nlyzed to determine these vribilities for the humerus. All dt re expressed s men ± SD. To ssess these vribilities, the interclss nd intrclss correltion coefficients were used (Wilcoxon Signed Rnks test).

4 758 Surg Rdiol Ant (2014) 36: Results Vribility or reproducibility Length vlues of the long nd the trnsverse xes of the glenoid, nd ngle vlues of the plne including the shft xis nd the hed center to the equtor on the hed surfce were 36.0 ± 3.0 mm, 22.5 ± 2.1 mm, 10.0 ± 8.8. Those vlues in ten glenoid nd humerl bones showed the vribility or the reproducibility ws high with correltion coefficient rnging from 0.73 to 0.98 (Wilcoxon Signed Rnks test) (Tble 1). The humerl shft showed 102 ± 9 of elevtion in the plne which fces 7 ± 8 to the scpulr plne on the glenoid. Axil rottion ws fixed with the glenoidl long xis prllel to the equtor (within 2 ). Figure 3 shows which portion of the hed surfce the center of the glenoid ws locted on. It showed the glenoid locted on the portion (Zone I) of the hed in ll subjects. The humerl hed centers nd shft xes projected on the glenoidl plne re shown in Fig. 4. The center of the humerl hed projects pproximtely on the center of the glenoid, showing the humerl hed remined centered in the glenoid cvity, nd the shft xes were locted bove these centers. The sme length of xis ws projected, nd the lengths of their shdows were different between the subjects, indicting the ngle of the shft to the glenoid vried. However, the humerl xis tilted in bout the sme direction (ntero-ly) bove the center of the glenoid. The direction of the shft tilting ws the sme s tht of trnsltion from the top of the hed to ech glenoid loction s ws mentioned bove. The finl position ws proved to be the sme in ll subjects, suggesting this position is unique nd my be reched whtever the course of the humerus. Tble 1 Vribility or reproducibility Angle of the plne including the shft xis nd the hed center to the equtor Men ± SD Men ± SD Correltion coefficient Vribility Length: Glenoidl long xis (mm) 36.2 ± ± Length: Glenoidl trnsverse xis (mm) 22.6 ± ± Angle ( ) 12.3 ± ± Reproducibility Length: Glenoidl long xis (mm) 36.2 ± ± Length: Glenoidl trnsverse xis (mm) 22.6 ± ± Angle ( ) 12.3 ± ± Fig. 3 The centers of the glenoid (blck dot) locted on the ntero- portion of the hed. The equtor (solid line) nd the longitude (solid curved line) crossing the top on the equtor, divide the hed surfce into four res. bicipitl groove, LT lesser tuberosity, GT greter tuberosity medil LT ZONE I 20 ZONE II TOP GT -40 ZONE III -60 ZONE IV TOP GT LT the center of the hed the equtor medil the xis of the humerl shft

5 Surg Rdiol Ant (2014) 36: * * 0.2 the xis of the humerl shft 0.4 the center of the hed b S A P I Fig. 4 Reltionship between the shft xis nd the hed center projected on the glenoidl plne is shown. The shft xes (blck rrow) except two subjects (sterisk) directed obliquely in the ntero- direction bove the hed center (blck dot). The length is dependent on the ngle of the shft tilting on the glenoid, indicting tht the shorter is the length of the rrow, the more verticl is the shft to the glenoid surfce. b The computer screen disply shows the long nd the trnsverse xes of the glenoid, the humerl shft xis (blck rrow). The center of the grid on the computer screen consisted with the center of the humerl hed which ws cut by the plne including its center. A rim, P posterior rim, S rim, I inferior rim, bicipitl groove Discussion The glenohumerl joint ws considered to rech generl position t the end of rising the rm whtever the psswy followed by the humerus [4, 6, 11, 13]. However, there hs been no precise in vivo description of the glenohumerl joint in mximum elevtion. Some discrepncies existed in the pst studies bout the position of the glenohumerl position in mximum elevtion. Browne et l. [3] found tht the plne of mximum elevtion ws 23 to the scpulr plne, while Perl et l. [15] reported the sme plne ws 4 posterior to the scpulr plne. One reson for explining the discrepncies might be tht those studies used different methods. The former ws cdveric study nd the ltter study used the scpulr locting device for estimting loctions of the scpul in vivo. Cdveric

6 760 Surg Rdiol Ant (2014) 36: Fig. 5 The glenoid center (X), locting in the Zones III or IV, moves upwrd with rnges of rottion getting restricted during the rm elevtion. In the figure, four glenoid centers with lower bduction ngle re shown. They converge to the top (blck dot) of the hed on the equtor with the glenoidl long xis prllel to the equtor. At this point the shft would become perpendiculr to the glenoid nd the joint might be locked in xil rottion. When the rm is more elevted, the glenoid would only trnslte to the ntero- portion (Zone I) of the humerl hed without xil rottion LT glenoid center t mximum elevtion glenoid mrgin top GT glenoid centers t lowerbducted positions humerl shft xis center glenoid plne top the equtor b studies possess limittions in tht the scpul is ffixed to support without outer muscles s well s the clvicle nd ribs. On the other hnd, locting devices hve problem in estimtion of loction of the bones. Three-dimensionl computer-generted MRI without rdition exposure on subjects would be pproprite for nlyzing sttic position becuse reltions between the bony lndmrks cn be investigted through tril nd error on computer screen. For investigting rottionl lignment of the joint, we set the equtor nd its prllel lines on the surfce of the humerl hed. The equtor ws determined to include the bicipitl groove becuse severl uthors [4, 12, 13] suggested its importnce to glenohumerl motion or position. In the result, ll subjects showed tht the glenoidl long xis becme prllel to the equtor in mximum elevtion. As long s xil rottion in the glenohumerl joint is expressed s rottionl ngle of the humerl xis, those vlues possibly re vrying. One reson for this vrition might be tht the hed hs offset nd ngle of retroversion depends on ech subject s ws suggested by ngle of the plne in Tble 1. To the best of our knowledge, this study ws the first representing concrete description bout ntomicl reltionship of rottion in mximum elevtion. Rnges of rottion would be restricted with rm elevtion becuse insertion of the short rottors pproches the glenoid surfce nd the cpsule surrounding the hed lso becomes tight. Thus, irrespective of the plne of elevtion, the shoulder joint would finlly converge to the sme, i.e., the preferentil position. Ggey et l. [6] described behvior of corcohumerl nd inferior glenohumerl ligments tht prticipte in determining the preferentil position. In their experimentl study, the xis of the humerl shft in tht position ws shown to be perpendiculr to the glenoid cvity nd it lso ws shown there still existed lterl rottion of the humerus llowing continution of elevtion s finl phse. Figure 5 illustrted the trjectory of the glenoid on the humerl hed during rm elevtion The glenoid moves upwrd on the surfce of the humerl hed, converging to the equtor with rnges of rottion getting restricted. When the glenoidl long xis becomes prllel to the equtor, the glenoid center is locted on the top of the hed, in which the joint is locked in xil rottion. Tht position would be essentilly the finl position of elevtion. When the rm is more elevted fter tht position, the glenoid would only trnslte to the ntero- portion of the humerl hed without xil rottion (Fig. 5, b). In fct, the direction of its trnsltion ws the sme s tht of the shft tilting on the glenoid. Our dt supported the studies by Browne et l. [4] showing the plne of mximum elevtion ws to the plne of the scpul. Certin shortcomings of this study must be cknowledged. A surgicl mttress ws dopted round elevted rm nd body in stnding position nd the ngle of the upper extremity to the trunk ws reproduced in n open MRI system. However, ech prticipnt hd to lie in supine position in the system nd it ws possible his or her position of the joint ws chnged. Systems with upright coils should be used for directly investigting the difference in reltionship in stnding or sitting positions nd tht would enble determining the effect of grvity on the glenohumerl reltionship. We could not clrify which prt of ntomy ws essentil for determining the positioning in mximum elevtion in this study. Informtion bout cses

7 Surg Rdiol Ant (2014) 36: with rottor cuff ter or without the long hed of the biceps might be helpful for clrifying which prt of the joint is essentil to determine the positioning. Experiments like ex vivo studies simulting rottor cuff ters [2, 18] might lso be useful to know the mechnism round mximum elevtion. Even though those limittions should be tken into considertion, the current study might be sufficient to describe the sttic position of the glenohumerl joint in mximum elevtion. The result of the study suggested () the position in which the glenoid is on the top of the humerl hed with the humerl shft perpendiculr to the glenoid is essentilly the finl position of elevtion, nd (b) the humerl xis is slightly to the plne of the scpul nd no xil rottion is vilble for the humerus fter tht finl position. Rehbilittion progrms iming t reching this position when the joint is impired fter injury or opertion would be resonble from this biomechnicl point of view. Conflict of interest The uthors declre tht they hve no conflict of interest. Open Access This rticle is distributed under the terms of the Cretive Commons Attribution License which permits ny use, distribution, nd reproduction in ny medium, provided the originl uthor(s) nd the source re credited. References 1. An KN, Browne AO, Korinek S, Tnk S, Morrey BF (1991) Three-dimensionl kinemtics of glenohumerl elevtion. J Orthop Res 9: Billurt F, Devun L, Ggey O et l (2007) 3D kinemtics of the glenohumerl joint during bduction motion: n ex vivo study. Surg Rdiol Ant 29(4): Browne AO, Hoffmeyer P, Tnk S, An KN, Morrey BF (1990) Glenohumerl elevtion studied in three dimensions. J Bone Joint Surg Br 72: Codmn EA (1934) The shoulder. Thoms Todd, Boston Freedmn L, Munro RR (1966) Abduction of the rm in the scpulr plne: scpulr nd glenohumerl movements. J Bone Joint Surg Am 48: Ggey O, Bonfit H, Gillot C, Hureu J, Mzs F (1987) Antomic bsis of ligmentous control of elevtion of the shoulder (reference position of the shoulder joint). Surg Rdiol Ant 9: Gold GE, Ppps GP, Whlen ST, Cmbell G, McAdms TA, Beulieu CF (2007) Abduction nd externl rottion in shoulder impingement: n open MR study on helthy volunteers initil experience. Rdiology 244: Innotti JP, Gbriel JP, Schneck SL, Evns, Misr S (1992) The norml glenohumerl reltionships. An ntomicl study of one hundred nd forty shoulders. J Bone Joint Surg Am 74: Inmn VT, Sunders JB, Abott LC (1944) Observtion on the function of the shoulder joint. J Bone Joint Surg Am 26: Inui H, Sugmoto K, Miymoto T, Yoshikw H, Mchid A, Hshimoto J, Nobuhr K (2002) Three-dimensionl reltionship of the glenohumerl joint in the elevted position in shoulders with multidirectionl instbility. J Shoulder Elb Surg 5: Ludewig PM, Phndke V, Brmn J, Hssett DR, Cieminski CJ, LPrde RF (2009) Motion of the shoulder complex during multiplnr humerl elevtion. J Bone Joint Surg Am 91: Mtsen FA III, Titlemn RM, Lippitt SB, Rockwood CA Jr, Wirth MA (2003) Glenohumerl instbility. In: Rockwood CA Jr, Msten FA III, Wirth MA, Lippitt SB (eds) The shoulder, 3rd edn. WB Sunders, Phildelphi, pp Nobuhr K (2003) Biomechnics of the shoulder. In: Nobuhr K (ed) The shoulder: its function nd clinicl spects. World Scientific, Singpore, pp Ogston JB, Ludewig PM (2007) Differences in 3-dimensionl shoulder kinemtics between persons with multidirectionl instbility nd symptomtic controls. Am J Sports Med 35: Perl ML, Jckins S, Lippitt SB, Sidles JA, Mtsen FA III (1993) Humeroscpulr positions in shoulder rnge-of-motion-exmintion. J Shoulder Elb Surg 6: Poppen NK, Wlker PS (1976) Norml nd bnorml motion of the shoulder. J Bone Joint Surg Am 58: Stokdijk M, Eilers PHC, Ngels J, Rozing PM (2003) Externl rottion in the glenohumerl joint during elevtion of the rm. Clin Biomech 18: Tetreult P, Levsseur A, Lin JC, Lin JC, de Guise J, Nuno N, Hgemeister N (2011) Pssive contribution of the rottor cuff to bduction nd joint stbility. Surg Rdiol Ant 33(9):