北京大學(xué)人民醫(yī)院

臨界髖關(guān)節(jié)發(fā)育不良BorderlineDDH(3)：股骨骨骺髖臼頂指數(shù)（TheFemoro-EpiphysealAcetabularRoof(FEAR)index）：一個(gè)預(yù)測(cè)髖關(guān)節(jié)穩(wěn)定性具有很高價(jià)值的功能參數(shù)作者：MichaelWyatt,JanWeidner,DominikPfluger,MartinBeck.作者單位:ClinicforOrthopaedicandTraumaSurgery,LuzernerKantonsspital,Spitalstrasse4,6004,Lucerne,Switzerland.michaelcharleswyatt@icloud.com.譯者：陶可（北京大學(xué)人民醫(yī)院骨關(guān)節(jié)科）摘要TheFemoro-EpiphysealAcetabularRoof(FEAR)index:股骨骨骺髖臼頂指數(shù)FEAR指數(shù)是最近描述的一個(gè)預(yù)測(cè)髖關(guān)節(jié)穩(wěn)定性具有很高價(jià)值的參數(shù)。它是由髖臼頂與股骨生長(zhǎng)板中央1/3處之間的夾角。其依據(jù)是：在生長(zhǎng)過程中，股骨的骨骺生長(zhǎng)板會(huì)垂直于髖關(guān)節(jié)的關(guān)節(jié)反作用力。股骨頸的生長(zhǎng)和方向受股骨頸下生長(zhǎng)板的控制。Pauwels和Maquet等提出理論，合力作用于骨骺軟骨的中心，在生長(zhǎng)過程中，根據(jù)Heuter-Volkman原理，骨骺板會(huì)垂直于關(guān)節(jié)反作用力。Pauwels和Maquet的理論后來得到了Carter等人的證實(shí)，他們通過二維有限元分析研究了髖關(guān)節(jié)負(fù)荷的影響。閉合的骨骺板的角度表示跨股骨近端骨骺的力的平衡，也表示跨關(guān)節(jié)力在過去的作用方式。因此，它是一個(gè)功能參數(shù)，反映了髖關(guān)節(jié)在生長(zhǎng)過程中長(zhǎng)期的關(guān)節(jié)反作用力。如果FEAR<0°(角開口向內(nèi))，則認(rèn)為髖關(guān)節(jié)穩(wěn)定。統(tǒng)計(jì)分析表明，5°的臨界值預(yù)測(cè)穩(wěn)定性的概率為80°。最近的研究表明，2°的臨界值預(yù)測(cè)穩(wěn)定性的概率為90%（Batailler等人，正在準(zhǔn)備發(fā)表中）。摘要背景：在放射學(xué)臨界髖關(guān)節(jié)發(fā)育不良中，骨性不穩(wěn)定性很難定義。因此，可靠的放射學(xué)工具（可幫助決策）——具體來說，可能與不穩(wěn)定性相關(guān)的工具——對(duì)這類患者非常有幫助。問題/目的：(1)比較一種新的放射學(xué)測(cè)量方法，我們稱之為股骨-骨骺髖臼頂(FEAR)指數(shù)，與側(cè)中心邊緣角(LCEA)和髖臼指數(shù)(AI)，以了解觀察者內(nèi)和觀察者間的可靠性；(2)將AI、頸干角、LCEA、髂關(guān)節(jié)囊體積、股骨前傾和FEAR指數(shù)與穩(wěn)定和不穩(wěn)定臨界髖關(guān)節(jié)發(fā)育不良接受的手術(shù)治療相關(guān)聯(lián)；以及(3)評(píng)估FEAR指數(shù)是否與臨界髖關(guān)節(jié)發(fā)育不良的臨床不穩(wěn)定性相關(guān)。方法：我們使用兩名盲法獨(dú)立觀察員在10張無癥狀對(duì)照的標(biāo)準(zhǔn)化X線片中定義和驗(yàn)證了FEAR指數(shù)。計(jì)算了評(píng)分者間和評(píng)分者內(nèi)系數(shù)，并輔以Bland-Altman圖。我們將其可靠性與LCEA和AI進(jìn)行了比較。我們進(jìn)行了一項(xiàng)病例對(duì)照研究，使用39例經(jīng)手術(shù)治療的有癥狀的臨界放射學(xué)髖關(guān)節(jié)發(fā)育不良和20例年齡匹配的無癥狀髖關(guān)節(jié)對(duì)照者的標(biāo)準(zhǔn)化X線片（比例為2:1），后者是因與髖關(guān)節(jié)無關(guān)的創(chuàng)傷而到我們機(jī)構(gòu)就診的患者，但在2016年1月1日至2016年3月1日期間進(jìn)行了標(biāo)準(zhǔn)化骨盆X線片檢查。使用單變量Wilcoxon雙樣本檢驗(yàn)評(píng)估患者的人口統(tǒng)計(jì)數(shù)據(jù)。各研究組的平均年齡沒有差異（總體：31.5±11.8歲[95%CI,27.7-35.4歲]；穩(wěn)定臨界DDH組：平均32.1±13.3歲[95%CI,25.5-38.7歲]；不穩(wěn)定臨界DDH組：平均31.1±10.7歲[95%CI,26.2-35.9歲]；p=0.96）。接受的治療是髖臼周圍截骨術(shù)（如果髖關(guān)節(jié)不穩(wěn)定），或者對(duì)于股骨髖臼撞擊患者，接受開放式或關(guān)節(jié)鏡下股骨髖臼撞擊手術(shù)。首先使用Wilcoxon雙樣本檢驗(yàn)（雙側(cè)）評(píng)估所接受的治療類別與變量AI、頸干角、LCEA、髂關(guān)節(jié)囊體積、股骨前傾和FEAR指數(shù)之間的關(guān)聯(lián)，然后進(jìn)行逐步多元邏輯回歸分析，以確定組合環(huán)境中的潛在相關(guān)變量。計(jì)算了敏感性、特異性和受試者工作曲線。主要終點(diǎn)是FEAR指數(shù)與不穩(wěn)定性之間的關(guān)聯(lián)，我們將其定義為股骨頭移位（在常規(guī)X線片上已經(jīng)可見）或在AP外展視圖上重新集中、Shenton線斷裂或MR關(guān)節(jié)造影時(shí)在后下關(guān)節(jié)間隙出現(xiàn)新月形釓積聚。結(jié)果：FEAR指數(shù)顯示出出色的觀察者內(nèi)和觀察者間可靠性，優(yōu)于AI和LCEA。與不穩(wěn)定臨界DDH組（平均值，13.3±15.2；95%CI，6.2-20.4）相比，穩(wěn)定臨界DDH組的FEAR指數(shù)較低（平均值，-2.1±8.4；95%CI，-6.3至2.0）（p<0.001），并且與所接受的治療的相關(guān)性最高。FEAR指數(shù)小于5°時(shí)，將髖關(guān)節(jié)正確分為穩(wěn)定和不穩(wěn)定的概率分別為79%（敏感性78%；特異性80%）。結(jié)論：LCEA為25°或更小且FEAR指數(shù)小于5°的疼痛髖關(guān)節(jié)很可能是穩(wěn)定的，在這種情況下，診斷重點(diǎn)可能更有效地集中在股骨髖臼撞擊上，因?yàn)楣晒求y臼撞擊是患者疼痛的潛在原因，而不是髖關(guān)節(jié)不穩(wěn)定。?討論臨界發(fā)育不良是一種放射學(xué)定義，由LCEA量化[19]。不幸的是，這種放射學(xué)發(fā)現(xiàn)并不能說明髖關(guān)節(jié)的臨床穩(wěn)定性。其他因素也會(huì)導(dǎo)致不穩(wěn)定；這些因素包括前傾、髖臼頂傾角和頸干角。雖然將臨界髖關(guān)節(jié)分類為穩(wěn)定或不穩(wěn)定對(duì)于成功治療這些髖關(guān)節(jié)是必要的，但在實(shí)踐中很難做到這一點(diǎn)，可能會(huì)導(dǎo)致治療不當(dāng)。特別是，如果錯(cuò)誤地推測(cè)問題是FAI而不是不穩(wěn)定，并進(jìn)行髖關(guān)節(jié)鏡檢查來治療，這可能會(huì)導(dǎo)致不穩(wěn)定癥狀持續(xù)存在。必須解決的問題不是髖關(guān)節(jié)是發(fā)育不良還是臨界發(fā)育不良，而是髖關(guān)節(jié)是穩(wěn)定還是不穩(wěn)定。因此，關(guān)鍵是準(zhǔn)確地將髖關(guān)節(jié)歸類為其中一種，然后進(jìn)行相應(yīng)的治療。傳統(tǒng)上，LCEA用于將髖關(guān)節(jié)分為正常、邊緣或發(fā)育不良。然而，LCEA并不總是能預(yù)測(cè)髖關(guān)節(jié)的穩(wěn)定性。為了幫助決策，我們提出了一種新的放射學(xué)參數(shù)，該參數(shù)可以在標(biāo)準(zhǔn)化AP骨盆X線片上可靠地測(cè)量。本研究的目的是評(píng)估這個(gè)FEAR指數(shù)，看看它是否與臨界不穩(wěn)定髖關(guān)節(jié)的病理行為有關(guān)。這項(xiàng)研究是有限的，因?yàn)榧{入的患者數(shù)量很少，無法進(jìn)行精確的患者匹配。更詳盡的參數(shù)匹配，如全身韌帶松弛的跡象、BMI和肌肉調(diào)節(jié)將是有利的。此外，回顧性研究使我們能夠顯示關(guān)聯(lián)，但不能做出預(yù)測(cè)。因此，有必要進(jìn)行未來的前瞻性研究，以顯示FEAR指數(shù)是否預(yù)測(cè)進(jìn)行性不穩(wěn)定。我們還通過各種參數(shù)來定義不穩(wěn)定性，包括MR關(guān)節(jié)造影上后下方釓的聚集、股骨頭的旋轉(zhuǎn)中心重新定位或Shenton線的斷裂，而不是純粹基于放射學(xué)；這導(dǎo)致了對(duì)不穩(wěn)定性的功能性定義。我們嘗試通過讓兩名對(duì)患者所接受的治療不知情的人員進(jìn)行測(cè)量來解決評(píng)估者偏見的問題。我們的研究結(jié)果表明，我們的新指數(shù)表現(xiàn)出極好的觀察者間和觀察者內(nèi)信度，優(yōu)于LCEA和AI。這種優(yōu)越性可能是因?yàn)殡y以定義髖臼底部的邊緣，正如所提到的[16]。已發(fā)表了幾項(xiàng)研究專門關(guān)注臨界髖關(guān)節(jié)發(fā)育不良的手術(shù)治療結(jié)果，其中一項(xiàng)研究顯示邊緣性髖關(guān)節(jié)的失敗率高于具有足夠髖臼覆蓋的髖關(guān)節(jié)[10]，另一項(xiàng)研究顯示結(jié)果基本一致[15]。目前髖關(guān)節(jié)的穩(wěn)定性通過LCEA進(jìn)行評(píng)估。意識(shí)到LCEA的局限性，有人嘗試使用臨界髖關(guān)節(jié)的其他參數(shù)作為髖關(guān)節(jié)不穩(wěn)定的替代指標(biāo)，例如盂唇大小或髂關(guān)節(jié)囊體積，已知這兩個(gè)結(jié)構(gòu)在髖關(guān)節(jié)發(fā)育不良時(shí)通常會(huì)肥大[1,8,11]。引入FEAR指數(shù)是評(píng)估髖關(guān)節(jié)功能穩(wěn)定性的新嘗試，其基于生長(zhǎng)板在生長(zhǎng)過程中垂直于關(guān)節(jié)反作用力的生物力學(xué)概念[5,6,8,9]。在對(duì)照組和穩(wěn)定臨界DDH組中，F(xiàn)EAR指數(shù)具有向內(nèi)張開的角度，即向內(nèi)指向的向量，表示向內(nèi)指向的關(guān)節(jié)反作用力和穩(wěn)定性。在發(fā)育不良組(13°)中，角度向外側(cè)張開，表示關(guān)節(jié)反作用力有利于關(guān)節(jié)的橫向移位和不穩(wěn)定。我們的研究不支持髂關(guān)節(jié)囊體積作為邊緣發(fā)育不良髖關(guān)節(jié)的鑒別因素。這與Babst等人的研究相反[1]。這可能歸因于患者的選擇。Babst等[1]將髖關(guān)節(jié)發(fā)育不良與鉗狀FAI髖關(guān)節(jié)進(jìn)行了比較，我們將不穩(wěn)定髖關(guān)節(jié)與穩(wěn)定性臨界髖關(guān)節(jié)進(jìn)行了比較，解剖學(xué)差異很小。我們建議進(jìn)一步研究以檢驗(yàn)這一點(diǎn)，因?yàn)槲覀兊难芯勘砻鼢年P(guān)節(jié)囊體積與股骨前傾之間存在相關(guān)性。FEAR指數(shù)的統(tǒng)計(jì)建模表明，這可能成為識(shí)別可能表現(xiàn)為穩(wěn)定的臨界髖關(guān)節(jié)的有用工具。這可能有利于識(shí)別適合髖關(guān)節(jié)鏡檢查的髖關(guān)節(jié)。79%的髖關(guān)節(jié)被正確識(shí)別為穩(wěn)定的臨界髖關(guān)節(jié)，靈敏度為80%，特異性為78%，F(xiàn)EAR指數(shù)似乎適合識(shí)別穩(wěn)定的髖關(guān)節(jié)。FEAR指數(shù)識(shí)別不穩(wěn)定的能力不太令人鼓舞，這可能反映了其他因素，例如韌帶松弛與決策過程有關(guān)。有趣的是，有癥狀的FAI患者中，關(guān)節(jié)過度活動(dòng)更為普遍[10,14]。我們認(rèn)為FEAR指數(shù)可能適用于包括標(biāo)準(zhǔn)射線照相在內(nèi)的全面臨床和放射學(xué)檢查，最好將MR關(guān)節(jié)造影術(shù)作為標(biāo)準(zhǔn)的第一步。MR關(guān)節(jié)造影術(shù)在檢測(cè)髖關(guān)節(jié)不穩(wěn)定方面優(yōu)于MRI，因?yàn)榭梢杂^察到新月征。必須尋找不穩(wěn)定的跡象，例如標(biāo)準(zhǔn)X線片上的股骨頭移位和MR關(guān)節(jié)造影上的新月征。如果存在，則必須通過髖臼周圍截骨術(shù)來穩(wěn)定髖關(guān)節(jié)。如果仍不確定髖關(guān)節(jié)是否穩(wěn)定，可以使用FEAR指數(shù)來評(píng)估穩(wěn)定性的可能性。我們發(fā)現(xiàn)，如果患者出現(xiàn)髖關(guān)節(jié)疼痛和臨界發(fā)育不良（定義為L(zhǎng)CEA20°至25°），F(xiàn)EAR指數(shù)小于5°表示髖關(guān)節(jié)穩(wěn)定的可能性為80%，如果FEAR指數(shù)增加1°，發(fā)生撞擊的幾率會(huì)降低24%。在這種情況下，F(xiàn)AI似乎比發(fā)育不良更有可能；然而，在確定FAI診斷之前，應(yīng)考慮并排除其他原因。如有指征，應(yīng)相應(yīng)選擇手術(shù)治療。需要進(jìn)一步研究以前瞻性驗(yàn)證FEAR指數(shù)。?Fig.1A–COurmeasurements,usingthepicturearchivingandcommunicationsystem(PACS)measurementdevice,of(A)theFEARindex;(B)LCEA;and(C)AIareshown.StandardizedAPpelvicradiographsof10asymptomaticcontrolpatientstreatedforunrelatedtraumaatourinstitutionduringJanuary2016wereselectedforthemeasurements.Nopatientshadpriorhipproblems.UsingthedigitalmeasurementtoolsontheMerlinpicturearchivingandcommunicationsystem(PACS)(Ph?nixMerlinSoftware5.0;Ph?nixPACSGmbH,Freiburg,Germany),twoindependentreviewers(MCWandJW)measuredtheFEARindex,LCEA,andAI,whichwedefinedastheangleofthesourcilversusthehorizontal(Fig.1).圖1A–C?我們使用圖片存檔和通信系統(tǒng)(PACS)測(cè)量設(shè)備測(cè)量了(A)FEAR指數(shù)；(B)LCEA；和(C)AI。選擇了2016年1月在我們機(jī)構(gòu)接受無關(guān)創(chuàng)傷治療的10名無癥狀對(duì)照患者的標(biāo)準(zhǔn)化AP骨盆X線片進(jìn)行測(cè)量。沒有患者之前有髖關(guān)節(jié)問題。使用Merlin圖片存檔和通信系統(tǒng)(PACS)上的數(shù)字測(cè)量工具（Ph?nixMerlinSoftware5.0；Ph?nixPACSGmbH，德國弗萊堡），兩名獨(dú)立審查員（MCW和JW）測(cè)量了FEAR指數(shù)、LCEA和AI（我們將其定義為髖臼眉弓與水平線之間的夾角）（圖1）。Fig.2A–BBland-AltmanplotsareshownfortheFEARindexforthe(A)firstand(B)secondmeasurements.Theinter-andintraobserverreliabilitywasfairtogoodfortheLCEA,whereastheAIwasexcellentforbothyetinferiortotheFEARindex.TheFEARindexdidnotvarysubstantiallybetweenassessorsforeachreplication(Fig.2).圖2A–B?顯示了(A)第一次和(B)第二次測(cè)量的FEAR指數(shù)的Bland-Altman圖。對(duì)于LCEA來說，觀察者間和觀察者內(nèi)信度為中等至良好，而AI對(duì)兩者而言都非常好，但不如FEAR指數(shù)。評(píng)估者之間的FEAR指數(shù)在每次重復(fù)中沒有顯著差異（圖2）。Fig.3AboxplotoftheFEARindexversustreatmentgroupisshown.Therewasnodifferenceinmeanage(overall:31.5±11.8years[95%CI,27.7–35.4years];stableborderlinegroup:mean,32.1±13.3years[95%CI,25.5–38.7years];unstableborderlinegroup:mean,31.1±10.7years[95%CI,26.2–35.9years])betweenstudygroups..TheFEARindexwashigheramongthegroupswithFAIandunstabletreatmentcomparedwiththeasymptomaticcontrolgroup(mean?2.1±8.4and13.3±15.2respectivelyversus?7.7±7.1forcontrols;p<0.001)(Fig.3).圖3?顯示了FEAR指數(shù)與治療組的箱線圖。各研究組間平均年齡無差異（總體：31.5±11.8歲[95%CI,27.7–35.4歲]；穩(wěn)定臨界DDH組：平均32.1±13.3歲[95%CI,25.5–38.7歲]；不穩(wěn)定臨界DDH組：平均31.1±10.7歲[95%CI,26.2–35.9歲]）。FAI組和不穩(wěn)定治療組的FEAR指數(shù)高于無癥狀對(duì)照組（平均-2.1±8.4和13.3±15.2，對(duì)照組為-7.7±7.1；p<0.001）（圖3）。Fig.4Athree-dimensionalscattergraphshowstheLCEA,AI,andFEARindex.Inaddition,theFEARindexyieldedthegreatestdistinctionwithrespecttotreatmentstatus(impingementborderlinegroupmean?2.1±8.4versusunstableborderlinegroupmean13.3±15.2;p<0.001)comparedwiththeLCEA(impingementborderlinegroup20±3.1versusunstableborderlinegroupmean13.7±8.3;p<0.001)andAI(impingementborderlinegroup13.6±3.6versusunstableborderlinegroupmean19.2±6.8;p=0.006),respectively(Fig.4).Iliocapsularisvolume,neck-shaftangle,andfemoralantetorsiondidnotdiscriminatebetweentreatmentgroups.However,inourstudy,iliocapsularisvolumehadapositiveassociationwithfemoralantetorsion,thatis,alargeriliocapsularisvolumewasassociatedwithgreaterantetorsion.圖4?三維散點(diǎn)圖顯示LCEA、AI和FEAR指數(shù)。此外，與LCEA（撞擊臨界DDH組20±3.1對(duì)比不穩(wěn)定臨界DDH組平均值13.7±8.3；p<0.001）和AI（撞擊臨界DDH組13.6±3.6對(duì)比不穩(wěn)定臨界DDH組平均值19.2±6.8；p=0.006）相比，F(xiàn)EAR指數(shù)在治療狀態(tài)方面產(chǎn)生了最大的區(qū)別（撞擊臨界DDH組平均值-2.1±8.4對(duì)比不穩(wěn)定臨界DDH組平均值13.3±15.2；p<0.001）（圖4）。髂關(guān)節(jié)囊體積、頸干角和股骨前傾在治療組之間沒有區(qū)別。然而，在我們的研究中，髂關(guān)節(jié)囊體積與股骨前傾呈正相關(guān)，也就是說，髂關(guān)節(jié)囊體積越大，前傾越大。Fig.5TheROCforFEARindexmodelisshown(areaunderthecurve=0.8944).Thisisshowngraphically(Fig.5).ThevalueofareaunderthecurveinthisROCcurvebeingclosetotheupperleftcornerindicatesthattheFEARindexhasaveryhighassociationwithinstability.圖5?顯示了FEAR指數(shù)模型的ROC（曲線下面積=0.8944）。這以圖形方式顯示（圖5）。此ROC曲線中曲線下面積的值接近左上角，表明FEAR指數(shù)與不穩(wěn)定性有非常高的關(guān)聯(lián)性。?DiscussionBorderlinedysplasticisaradiographicdefinitionthatisquantifiedbytheLCEA[19].Unfortunatelythisradiographicfindingdoesnotgiveanyindicationregardingtheclinicalstabilityofthehip.Additionalfactorscontributetoinstability;theseincludeantetorsion,acetabularroofinclination,andneckshaftangle.Althoughthecategorizationofborderlinehipsasstableorunstableisnecessaryforsuccessfultreatmentofthesehips,thiscanbedifficulttodoinpracticeandmayleadtoincorrecttreatment.Inparticular,ifonemistakenlysurmisestheproblemisFAIratherthaninstabilityandperformshiparthroscopytotreatit,thislikelywillresultinpersistentsymptomsfrominstability.Thequestionthathastobeaddressedisnotwhetherahipisdysplasticorborderlinedysplastic,butwhetherthehipisstableorunstable.Thekeythereforeistoclassifythehipaccuratelyasoneortheotherandthentreatitaccordingly.Traditionally,theLCEAwasusedtocategorizehipsasnormal,borderline,ordysplastic.However,theLCEAdoesnotalwayspredictstabilityofthehip.Toaiddecision-making,wehaveproposedanewradiographicparameterthatcanbemeasuredreliablyonstandardizedAPpelvicradiographs.ThepurposeofthisstudywastoevaluatethisFEARindextoseewhetheritisassociatedwithpathologicbehaviorintheborderline-unstablehip.Thestudyislimitedbecausewiththesmallnumberofpatientsincluded,precisepatientmatchingcouldnotbeperformed.More-exhaustivematchingforparameterslikesignsofgeneralizedligamentouslaxity,BMI,andmuscularconditioningwouldbeadvantageous.Furthermore,aretrospectivestudyallowsustoshowassociationsbutnottomakepredictions.ThereforefutureprospectivestudiestoshowwhethertheFEARindexpredictsprogressiveinstabilityarewarranted.Wealsodefinedinstabilitybyvariousparameters,includingpoolingofgadoliniumposteroinferiorlyonMRarthrography,recenteringofthefemoralheadorabreakinShenton’slineandratherthanonapurelyradiographicbasis;thisresultsinafunctionaldefinitionofinstability.Weattemptedtoaddresstheissueofassessorbiasbyhavingtwoindividualsblindedtothetreatmentspatientsreceivedperformthemeasurements.Thefindingsfromourstudyshowthatournewindexshowsexcellentinter-andintraobserverreliabilityandwassuperiortotheLCEAandAI.Thissuperioritymaybebecauseofdifficultyindefiningtheedgeoftheacetabularsourcilashasbeenalludedto[16].?Acoupleofstudieshavebeenpublishedlookingspecificallyattheresultsofsurgicaltreatmentofborderlinedysplastichips,withonestudyshowinghigherratesoffailureintheborderlinehipsthaninthosewithadequateacetabularcover[10],andtheotherstudyshowingcomparableoutcomes[15].CurrentlystabilityofthehipisassessedwiththeLCEA.RealizingthelimitationsoftheLCEA,therehavebeenattemptstouseotherparametersinborderlinehipsassurrogatemarkersforhipinstability,suchasthesizeofthelabrumorthevolumeoftheiliocapsularis,bothstructuresknownoftentobehypertrophicinhipdysplasia[1,8,11].IntroducingtheFEARindexisanewattempttoassessfunctionalstabilityofthehip,basedonthebiomechanicalconceptthatthegrowthplateorientsitselfperpendicularlytothejointreactingforcesduringgrowth[5,6,8,9].Inthecontrolgroupandthestableborderlinegroup,theFEARindexhadamediallyopenangle,thatis,amediallydirectedvector,indicatingmedial-directedjoint-reactionforcesandstability.Inthedysplasticgroup(13°),theangleopenedlaterally,indicatingjoint-reactionforcesfavoringlateralmigrationandinstabilityofthejoint.Ourstudydidnotsupporttheiliocapsularisvolumeasadiscriminatorinborderlinedysplastichips.ThisiscontrarytothestudybyBabstetal.[1].Thisprobablyisattributabletopatientselection.Babstetal.[1]compareddysplastichipswithhipswithpincerFAIandwecomparedunstablewithstableborderlinehips,theanatomicdifferencebeingonlyminimal.Werecommendfurtherresearchtoexaminethis,becauseourstudyshowedacorrelationbetweeniliocapsularisvolumewithfemoralantetorsion.StatisticalmodelingoftheFEARindexsuggeststhatthiscouldbecomeausefultoolinidentifyingborderlinehipsthatlikelywillbehaveasstable.Thiscouldproveadvantageousinidentifyinghipsthatwouldbeappropriateforhiparthroscopy.With79%correctlyidentifiedasstableborderlinehipswithasensitivityof80%andspecificityof78%,theFEARindexseemssuitabletoidentifystablehips.TheabilityoftheFEARindextoidentifyinstabilitywaslessencouragingandthismayreflectotherfactorssuchasligamentouslaxitybeingpertinentinthedecision-makingprocess.Interestingly,hypermobilityhasbeennotedtobemoreprevalentinsymptomaticpatientswithFAI[10,14].WebelievetheFEARindexmightbeappliedinthecontextofathoroughclinicalandradiographicworkupincludingstandardradiographs,andpreferablyMRarthrographyremainsthestandardfirststep.MRarthrographyissuperiortoMRIfordetectionofhipinstabilitybecausethecrescentsigncanbeobserved.Signsofinstability,likemigrationofthefemoralheadonstandardradiographsandthecrescentsignonMRarthrography,havetobelookedfor.Ifpresent,thehiphastobestabilizedwithaperiacetabularosteotomy.Ifoneisstillundecidedwhetherthehipisstable,theFEARindexcanbeusedtoassessthelikelihoodofstability.Wefoundthatifapatientpresentswithhippainandborderlinedysplasia(definedasaLCEA20°to25°),aFEARindexlessthan5°indicatesan80%probabilitythatthehipisstable,andiftheFEARindexincreasesby1°,theoddsofhavingimpingementdecreasesby24%.Inthatsituation,FAIseemsmorelikelythandysplasia;however,othercausesshouldbeconsideredandexcludedbeforedeterminingadiagnosisofFAI.Surgicaltreatment,ifindicated,shouldbeselectedaccordingly.FurtherstudiesareneededtovalidatetheFEARindexprospectively.?TheFemoro-EpiphysealAcetabularRoof(FEAR)Index:ANewMeasurementAssociatedWithInstabilityinBorderlineHipDysplasia?AbstractBackground:Thedefinitionofosseousinstabilityinradiographicborderlinedysplastichipsisdifficult.Areliableradiographictoolthataidsdecision-making-specifically,atoolthatmightbeassociatedwithinstability-thereforewouldbeveryhelpfulforthisgroupofpatients.Questions/purposes:(1)Tocompareanewradiographicmeasurement,whichwecalltheFemoro-EpiphysealAcetabularRoof(FEAR)index,withthelateralcenter-edgeangle(LCEA)andacetabularindex(AI),withrespecttointra-andinterobserverreliability;(2)tocorrelateAI,neck-shaftangle,LCEA,iliocapsularisvolume,femoralantetorsion,andFEARindexwiththesurgicaltreatmentreceivedinstableandunstableborderlinedysplastichips;and(3)toassesswhethertheFEARindexisassociatedclinicalinstabilityinborderlinedysplastichips.Methods:WedefinedandvalidatedtheFEARindexin10standardizedradiographsofasymptomaticcontrolsusingtwoblindedindependentobservers.Interraterandintraratercoefficientswerecalculated,supplementedbyBland-Altmanplots.WecompareditsreliabilitywithLCEAandAI.Weperformedacase-controlstudyusingstandardizedradiographsof39surgicallytreatedsymptomaticborderlineradiographicallydysplastichipsand20age-matchedcontrolswithasymptomatichips(a2:1ratio),thelatterwerepatientsattendingourinstitutionfortraumaunrelatedtotheirhipsbutwhohadstandardizedpelvicradiographsbetweenJanuary1,2016andMarch1,2016.PatientdemographicswereassessedusingunivariateWilcoxontwo-sampletests.Therewasnodifferenceinmeanage(overall:31.5±11.8years[95%CI,27.7-35.4years];stableborderlinegroup:mean,32.1±13.3years[95%CI,25.5-38.7years];unstableborderlinegroup:mean,31.1±10.7years[95%CI,26.2-35.9years];p=0.96)amongstudygroups.Treatmentreceivedwaseitheraperiacetabularosteotomy(ifthehipwasunstable)or,forpatientswithfemoroacetabularimpingement,eitheranopenorarthroscopicfemoroacetabularimpingementprocedure.TheassociationofreceivedtreatmentcategorieswiththevariablesAI,neck-shaftangle,LCEA,iliocapsularisvolume,femoralantetorsion,andFEARindexwereevaluatedfirstusingWilcoxontwo-sampletests(two-sided)followedbystepwisemultiplelogisticregressionanalysistoidentifythepotentialassociatedvariablesinacombinedsetting.Sensitivity,specificity,andreceiveroperatorcurveswerecalculated.TheprimaryendpointwastheassociationbetweentheFEARindexandinstability,whichwedefinedasmigrationofthefemoralheadeitheralreadyvisibleonconventionalradiographsorrecenteringoftheheadonAPabductionviews,abreakofShenton'sline,ortheappearanceofacrescent-shapedaccumulationofgadoliniumintheposteroinferiorjointspaceatMRarthrography.Results:TheFEARindexshowedexcellentintra-andinterobserverreliability,superiortotheAIandLCEA.TheFEARindexwaslowerinthestableborderlinegroup(mean,-2.1±8.4;95%CI,-6.3to2.0)comparedwiththeunstableborderlinegroup(mean,13.3±15.2;95%CI,6.2-20.4)(p<0.001)andhadthehighestassociationwithtreatmentreceived.AFEARindexlessthan5°hada79%probabilityofcorrectlyassigninghipsasstableandunstable,respectively(sensitivity78%;specificity80%).Conclusions:ApainfulhipwithaLCEAof25°orlessandFEARindexlessthan5°islikelytobestable,andinsuchasituation,thediagnosticfocusmightmoreproductivelybedirectedtowardfemoroacetabularimpingementasapotentialcauseofapatient'spain,ratherthaninstability.文獻(xiàn)出處：MichaelWyatt,JanWeidner,DominikPfluger,MartinBeck.TheFemoro-EpiphysealAcetabularRoof(FEAR)Index:ANewMeasurementAssociatedWithInstabilityinBorderlineHipDysplasia?ComparativeStudy,ClinOrthopRelatRes.2017Mar;475(3):861-869.doi:10.1007/s11999-016-5137-0.