COPYRIGHT2008BYTHEJOURNALOFBONEANDJOINTSURGERY,INCORPORATEDI,,Treatment of Early Stage Osteonecrosis of the Femoral HeadBy David R. Marker, BS, Thorsten M. Seyler, MD, Mike S. McGrath, MD, Ronald E. Delanois, MD, Slif D. Ulrich, MD, and Michael A. Mont, MDIntroductionsteonecrosis is a devastating disease that primarily af-fects weight-bearing joints. The hip is the most com-monly affected joint. Although hip osteonecrosis canaffect patients of any age group, it typically presents in youngpatients between the ages of twenty and forty years1. The fac-tors that affect the progression of this disease are still not fullyunderstood,butradiographiclesionsize,femoralheadcol-lapse (if present), and, occasionally, clinical presentation at thetimeofdiagnosishavebeenshowntobepredictiveoftheeventualclinicaloutcome2,3.Aftercollapse,mostpatientswillrequireastandardtotalhiparthroplasty4,5.However,becauseof the young age of many of these patients, a hip replacementcannot be expected to last the patients lifetime and therefore,whenfeasible,attemptsshouldbemadetosavethefemoralhead prior to collapse with use of less invasive treatment mo-dalities.Theefficacyoftheseprocedureshasbeenvariable,with reported success rates ranging between 60% and 80% atthetimeofshort-termandmidtermfollow-up6-8.Currenttreatmentsrangefrompharmacotherapiestosurgicalinter-ventionsthatincludecoredecompression,vascularizedornonvascularized bone-grafting, and osteotomy. Recently therehave been attempts to enhance these surgical techniques withuse of various growth and differentiation factors.Theprimarypurposeofthisreportisthreefold:(1)todiscusstheimportanceofearlydiagnosisandthestandardsfor identifying and staging osteonecrosis; (2) to assess the effi-cacyofvarioustreatmentmodalitiesandtechniquesbycon-ducting an extensive literature review and comparing reportedoutcomes with those of patients treated at our institution; and(3) to provide a recommended treatment algorithm based onthe assessment of these treatment options.The Diagnosis and Staging of Osteonecrosisllpatientswhoweretreatedatourinstitutionforearlystage osteonecrosis of the hip and included in the presentstudywerediagnosedwithuseofthefollowingcriteria:(1)clinical presentation with throbbing, deep groin pain, and oneor more associated risk factors; or (2) a previous diagnosis ofosteonecrosis in another joint (Table I). Patients who met oneof these clinical criteria underwent subsequent magnetic reso-nanceimagingtoconfirmtheclinicaldiagnosis.Althoughconsidered less specific and not used as one of the diagnosticcriteria,aphysicalexaminationwasalsohelpfulindiagnosisbecause many patients had limited internal rotation of the hipinbothextensionandflexion.Themostcommonpresenta-tion was that of groin and/or occasional buttock pain that wasintermittent, described as deep and throbbing9, and of gradualonset.Thepaintypicallywasassociatedwithmovementandweight-bearingactivities,althoughsomepatientsprogressedtohavepainatrest.Inaminorityofthecases,thepainap-peared abruptly. There were also some patients who remainedrelativelyasymptomaticdespiteradiographicevidenceofad-vanced progression of the disease.Magnetic resonance imaging is generally accepted as thestandardforconfirmingasuspectedclinicaldiagnosisofos-teonecrosis,and,aspreviouslynoted,thismodalitywasusedto diagnose all patients included in the present study. The au-thors of a recent Japanese study developed a list of major andminorradiographiccriteriafordiagnosingosteonecrosis.Majorcriteriaincludedfemoralheadcollapse,evidenceofa crescent sign and demarcating sclerosis on radiographs, andlow-intensitybandsonT1-weightedmagneticresonanceimages. Minor criteria included joint-space narrowing, radio-graphicevidenceofmottledsclerosisandacetabularinvolve-ment,andhomogeneousorinhomogeneouslowintensitywithout the band pattern on T1-weighted magnetic resonanceimages10. Although bone scanning was previously advocated asausefuldiagnostictool11-13,thisimagingmodalityhassubse-quently been shown to have poor sensitivity. In a recent studyby Mont et al., the sensitivity of magnetic resonance imagingwas compared with that of bone scanning in sixty-one hipsOADisclosure: In support of their research for or preparation of this work, one or more of the authors received, in any one year, outside funding or grants of less than $10,000 from Ossacur AG, Oberstenfeld, Germany. In addition, one or more of the authors or a member of his or her immediate family received, in any one year, payments or other benefits of less than $10,000 or a commitment or agreement to provide such benefits from a commercial entity (Ossacur AG, Oberstenfeld, Germany). Also, a commercial entity (Ossacur AG, Oberstenfeld, Germany) paid or directed in any one year, or agreed to pay or direct, benefits in excess of $10,000 to a research fund, foundation, division, center, clinical practice, or other charitable or nonprofit organization with which one or more of the authors, or a member of his or her immediate family, is affiliated or associated.J Bone Joint Surg Am. 2008;90 Suppl 4:175-87 doi:10.2106/JBJS.H.00671Marker.fmPage 175Wednesday, October 15, 200812:53 PMI,oTHEJOURNALOFBONE&JOI NTSURGERY J BJ S. ORGVOLUME90-A SUPPLEMENT4 2008TREATMENTOFEARLYSTAGE OSTEONECROSI SOFTHEFEMORALHEADwithpathologicallyconfirmedosteonecroticlesions14.Whileall lesions were successfully identified with the use of magneticresonance imaging, only thirty-seven (61%) were detected bybone scan. The lowest sensitivity for bone scans was found inhips with early stage osteonecrosis (22% of Ficat and Arlet15,16stage-I hips and 36% of small lesions).Imagingisimportantinthediagnosisofhiposteone-crosis as well as in predicting outcome (Table II), and standardradiographsarecommonlyusedtostagetheprogressionofdisease.AlthoughthemostfrequentlyusedstagingsystemisthatofFicatandArlet15,16,anumberofothersystemshavebeenused,includingthosebytheUniversityofPennsylvania(alsoknownasSteinberg17,18),ARCO(AssociationResearchCirculationOsseous19-21),andTheJapaneseOrthopaedicAssociation22-24(TableIII).Onthebasisofthedifferencesinsome of the other most frequently used staging systems, it hasbeenreportedthatthereisnoacceptedwaytorelateoneofthese systems to another25. We do advocate collecting enoughdata to allow use of any of the most commonly used systems.In addition to these staging systems, the Kerboul angle and thearc of the affected necrotic area of the femoral head have beenusedtoevaluatelesionsize26,27.Bysummingthetwoanglesmeasured on the anteroposterior and lateral radiographs, thecombinednecroticangleisdeterminedtodefineasmall(250) lesion. If thesize is small (affecting