<?xml version="1.0"?>

<ownershipDocument>

    <documentType>4/A</documentType>

    <periodOfReport>2003-06-04</periodOfReport>

    <dateOfOriginalSubmission>2003-06-17</dateOfOriginalSubmission>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000722723</issuerCik>
        <issuerName>HANGER ORTHOPEDIC GROUP INC</issuerName>
        <issuerTradingSymbol>HGR</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001034464</rptOwnerCik>
            <rptOwnerName>LARKIN C RAYMOND JR</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>  </rptOwnerStreet1>
            <rptOwnerStreet2>  </rptOwnerStreet2>
            <rptOwnerCity>  </rptOwnerCity>
            <rptOwnerState>  </rptOwnerState>
            <rptOwnerZipCode>  </rptOwnerZipCode>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeSecurity>
        <securityTitle>
            <value>Common Stock</value>
        </securityTitle>
        <transactionDate>
            <value>2003-06-04</value>
        </transactionDate>
        <transactionCoding>
            <transactionFormType>4</transactionFormType>
            <transactionCode>A</transactionCode>
            <equitySwapInvolved>0</equitySwapInvolved>
        </transactionCoding>
        <transactionTimeliness>
            <value></value>
        </transactionTimeliness>
        <transactionAmounts>
            <transactionShares>
                <value>2070</value>
                <footnoteId id="F1"/>
            </transactionShares>
            <transactionValue>
                <value>0</value>
            </transactionValue>
            <transactionAcquiredDisposedCode>
                <value>A</value>
            </transactionAcquiredDisposedCode>
        </transactionAmounts>
        <postTransactionAmounts>
            <sharesOwnedFollowingTransaction>
                <value>2070</value>
            </sharesOwnedFollowingTransaction>
        </postTransactionAmounts>
        <ownershipNature>
            <directOrIndirectOwnership>
                <value>D</value>
            </directOrIndirectOwnership>
        </ownershipNature>
    </nonDerivativeSecurity>

    <derivativeSecurity>
        <securityTitle>
            <value>Non-Qualified Stock Option</value>
        </securityTitle>
        <conversionOrExercisePrice>
            <value>11.21</value>
        </conversionOrExercisePrice>
        <transactionDate>
            <value>2003-06-04</value>
        </transactionDate>
        <transactionCoding>
            <transactionFormType>4</transactionFormType>
            <transactionCode>A</transactionCode>
            <equitySwapInvolved>0</equitySwapInvolved>
        </transactionCoding>
        <transactionTimeliness>
            <value></value>
        </transactionTimeliness>
        <transactionAmounts>
            <transactionShares>
                <value>5535</value>
            </transactionShares>
            <transactionValue>
                <value>0</value>
            </transactionValue>
            <transactionAcquiredDisposedCode>
                <value>A</value>
            </transactionAcquiredDisposedCode>
        </transactionAmounts>
        <exerciseDate>
            <value>2004-06-04</value>
            <footnoteId id="F2"/>
        </exerciseDate>
        <expirationDate>
            <value>2013-06-04</value>
        </expirationDate>
        <underlyingSecurity>
            <underlyingSecurityTitle>
                <value>Common Stock</value>
            </underlyingSecurityTitle>
            <underlyingSecurityShares>
                <value>5535</value>
            </underlyingSecurityShares>
        </underlyingSecurity>
        <postTransactionAmounts>
            <sharesOwnedFollowingTransaction>
                <value>5535</value>
            </sharesOwnedFollowingTransaction>
        </postTransactionAmounts>
        <ownershipNature>
            <directOrIndirectOwnership>
                <value>D</value>
            </directOrIndirectOwnership>
        </ownershipNature>
    </derivativeSecurity>

    <footnotes>
        <footnote id="F1">Table 1 of this Form 4 reports the grant of 2,070 shares of restricted stock pursuant to the Company's 2003 Non-Employee Directors' Stock Incentive Plan in accordance with Rule 16b-3(d).  The shares will become 100% vested on June 4, 2004, subject to certain provisions of the Plan.</footnote>
        <footnote id="F2">This option becomes exercisable to the extent of one-third on the above date and is cumulatively exercisable to the extent of one-third each year thereafter.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Arden T. Phillips, Attorney-in-Fact</signatureName>
        <signatureDate>2003-06-30</signatureDate>
    </ownerSignature>

</ownershipDocument>

