<PAGE>   1
                                                                   EXHIBIT 10.18


       SPLIT DOLLAR INSURANCE AGREEMENT dated January 21, 1991, by and between
MARCY ABRAMSON, NANCY WOLFSON, JUDITH ABRAMSON, DAVID B. SOLL, JEROME GOODMAN
and EDWARD M. GLICKMAN, Trustees under Indenture of Trust of LEONARD ABRAMSON
and MADLYN K. ABRAMSON, dated as of November 1, 1990, ("Owner") and U.S.
HEALTHCARE, INC. ("Company").

       The parties hereto in consideration of the agreements and covenants
hereinafter set forth and intending to be legally bound, agree as follows:

       1.     This agreement relates to a policy of insurance ("Policy") on the
lives of Leonard Abramson and Madlyn K. Abramson ("Insureds") issued by the
Prudential Insurance Company of America (the "Insurer"), Policy No. 79 671 777.
Subject to the conditions hereinafter set forth, Owner shall be the sole owner
of the Policy.

       2.     The Company has heretofore and shall continue to pay the portion
of the annual premium on the Policy equal to the Company's "Cash Investment" in
the Policy, which shall be equal to: (i) the annual net premium, minus (ii) the
                                                                 -----
value of the death benefit to which Owner is then entitled, determined by using
the lesser of (a) the applicable one-year term premium cost computed under
Revenue Ruling 55-747, 1955-2 C.B. 228 (or any superseding ruling thereto) or
----------------------
(b) the applicable premium rates charged by the Insurer for initial issue
one-year term insurance. In any year, the "annual net premium" shall equal the
gross premium less policy dividends which are not used to


<PAGE>   2


purchase additional insurance. The Company shall also pay to or on behalf of the
Insureds a bonus equal to the remaining portion of the annual premium otherwise
payable by Owner.

       3.     In consideration of the payments made pursuant to paragraph 2
hereof, the Company shall receive from the proceeds of the Policy, upon the
death of the survivor of the Insureds (or upon the surrender of the Policy
during the Insureds' lifetimes) an amount equal to the Company's "Cash
Investment" in the Policy as calculated under paragraph 2 hereof. The balance of
the proceeds, if any, shall be paid as provided to the Owner.

       4.     To secure the Cash Investment, Owner shall assign to the Company a
security interest in the Policy equal in amount to the Cash Investment and such
security shall be limited to the Company's right to receive such amount out of
the proceeds of the policy.

       5.     The assignment to the Company provided for in this agreement shall
be effectuated by the execution of a Collateral Assignment Agreement
substantially in the form attached hereto as Exhibit "A".

       6.     Owner shall notify the Insurer of the Collateral Assignment
Agreement and shall take no action that would impair the security interest of
the Company under the Collateral Assignment Agreement.

       7.     Each and every right, interest or incident of ownership associated
with the Policy which is not expressly


                                       2
<PAGE>   3


assigned to the Company by the Collateral Assignment Agreement shall be retained
by Owner, including, but not limited to, the right to designate and change the
beneficiaries of the Policy, the right to transfer the Policy subject to the
rights assigned to the Company, the right to surrender the Policy subject to the
rights assigned to the Company, and the right to exercise any option provided in
the Policy.

       8.     Subject to taking notice of the Collateral Assignment Agreement
when it is filed at its home office, the Insurer shall have no obligation except
as set forth in the Policy. The Insurer shall not be bound to inquire into or
take notice of any of the covenants herein contained. Upon the Insureds' deaths
(or upon surrender of the Policy prior to the deaths of both Insureds), the
Insurer shall be discharged from its obligations upon payment of the proceeds in
accordance with the provisions of the Policy and the Collateral Assignment
Agreement and without regard to this agreement or any amendment hereof.

       9.     For purposes of the Employee Retirement Income Security Act of
1974, as amended ("ERISA"), the Company is the "Named Fiduciary" and
"Administrator" within the meaning of sections 402(a) and 3(16)(A) of ERISA,
respectively, and the fiduciary for deciding claims. All claims shall be
resolved under procedures which comply with regulations promulgated under
section 503 of ERISA.

       10.    Amendments may be made to this agreement by a writing signed by
each of the parties and attached hereto.



                                       3
<PAGE>   4


       11.    All matters respecting the validity, effect and interpretation of
this agreement shall be determined in accordance with the laws of the
Commonwealth of Pennsylvania.

       12.    This agreement shall be binding upon the parties hereto and their
successors and assigns.

       IN WITNESS WHEREOF, this agreement has been executed as of the date first
above written.

<TABLE>
<CAPTION>
<S>                                                 <C>
U.S. HEALTHCARE, INC.                                INDENTURE OF TRUST OF
                                                          LEONARD ABRAMSON AND
                                                          MADLYN K. ABRAMSON
                                                          DATED AS OF NOVEMBER 1, 1990

By:    /s/ Alan R. Letofsky (SR VP)                  By:   /s/ Marcy Abramson            (SEAL)
     ---------------------------------------               -----------------------------
                                                           Marcy Abramson

Attest:                                              /s/ Nancy A. Wolfson                (SEAL)
         -----------------------------------         -----------------------------------
         [Corporate Seal]                            Nancy Wolfson

                                                     /s/ Judith Abramson                 (SEAL)
                                                     -----------------------------------
                                                           Judith Abramson

                                                     /s/ David B. Soll, M.D.             (SEAL)
                                                     -----------------------------------
                                                           David B. Soll


                                                     /s/ Jerome S. Goodman, Jr.          (SEAL)
                                                     -----------------------------------
                                                           Jerome Goodman

                                                     /s/ Edward M. Glickman              (SEAL)
                                                     -----------------------------------
                                                           Edward M. Glickman, Trustees
</TABLE>



                                       4
<PAGE>   5


       COLLATERAL ASSIGNMENT AGREEMENT dated January 21, 1991, by and between
MARCY ABRAMSON, NANCY WOLFSON, JUDITH ABRAMSON, DAVID B. SOLL, JEROME GOODMAN
and EDWARD M. GLICKMAN, Trustees under Indenture of Trust of LEONARD ABRAMSON
and MADLYN K. ABRAMSON, dated as of November 1, 1990 ("Owner") and U.S.
HEALTHCARE, INC. (the "Company").

       This Agreement relates to The Prudential Insurance Company of America
Policy No. 79 671 777, ("Policy") on the lives of Leonard Abramson and Madlyn K.
Abramson ("Insureds").

       The parties have entered into a Split Dollar Insurance Agreement
contemporaneously with this Agreement ("Insurance Agreement").

       Pursuant to the Insurance Agreement, Owner has agreed to assign to the
Company a security interest in the Policy in order to provide for the payment to
the Company of the Cash Investment as defined in the Insurance Agreement.

       The parties hereto, in consideration of the foregoing and the agreements
and covenants hereinafter set forth and intending to be legally bound hereby,
agree as follows:

       1.     Owner hereby assigns to the Company a security interest in the
Policy in order to secure to the Company the payment of the Cash Investment in
the Policy, consisting of the following rights:


<PAGE>   6


              (a)    Upon the death of the survivor of the Insureds, the Company
shall have the right to receive so much of the proceeds payable under the Policy
as is equal to the Cash Investment, determined as of the date of the survivor's
death. The Company may collect such portion of the proceeds directly from the
Insurer.

              (b)    In the event the Policy is surrendered by Owner prior to
the deaths of both Insureds, the Company shall have the right to receive so much
of the proceeds received as is equal to the Cash Investment, determined as of
the date of surrender. The Company may collect such portion of the proceeds on
surrender of the Policy directly from the Insurer.

       (2)    The Insurer is authorized to rely solely on the written statement
of the Company and the Owner for the exercise of any rights under the Policy
assigned herein and as to the amount of the Cash Investment as of any date. The
Insurer is hereby authorized to recognize such statement without investigation
or the giving of any notice. The written acknowledgment of receipt by the
Company for any sums paid to it by the Insurer pursuant to the written statement
of the Cash Investment in the Policy shall be a full discharge and release of
the Insurer with respect to the Policy. Payment of the Cash Investment shall be
made to the exclusive order of the Company.


                                       2
<PAGE>   7


       3.     Each and every right, interest, or incident of ownership
associated with the Policy which is not expressly assigned to the Company by
this Collateral Assignment Agreement is retained by Owner, including, but not
limited to, the right to designate and change the beneficiaries of the Policy,
the right to transfer the Policy subject to the rights assigned to the Company,
and the right to exercise any option provided in the Policy.

       4.     Each of the undersigned declares that no proceedings in bankruptcy
are pending against it or them and that its or their property is not subject to
any assignment for the benefit of creditors.

       5.     All matters respecting the validity, effect and interpretation of
this Collateral Assignment Agreement shall be determined in accordance with the
laws of the Commonwealth of Pennsylvania.

       6.     This Collateral Assignment Agreement shall be binding upon the
parties hereto and their successors and assigns.

       IN WITNESS WHEREOF, the parties have hereunto set


                                       3
<PAGE>   8


their hands and seals as of the date first above written.


<TABLE>
<CAPTION>
<S>                                                  <C>
U.S. HEALTHCARE, INC.                                INDENTURE OF TRUST OF
                                                          LEONARD ABRAMSON AND
                                                          MADLYN K. ABRAMSON
                                                          DATED AS OF NOVEMBER 1, 1990

By:    /s/ Alan R. Letofsky (SR VP)                  By:   /s/ Marcy Abramson            (SEAL)
     ---------------------------------------               -----------------------------
                                                           Marcy Abramson

Attest:                                              /s/ Nancy A. Wolfson                (SEAL)
         -----------------------------------         -----------------------------------
         [Corporate Seal]                                  Nancy Wolfson

                                                     /s/ Judith Abramson                 (SEAL)
                                                     -----------------------------------
                                                           Judith Abramson

                                                     /s/ David B. Soll, M.D.             (SEAL)
                                                     -----------------------------------
                                                           David B. Soll


                                                     /s/ Jerome S. Goodman, Jr.          (SEAL)
                                                     -----------------------------------
                                                           Jerome Goodman

                                                     /s/ Edward M. Glickman              (SEAL)
                                                     -----------------------------------
                                                           Edward M. Glickman,
                                                                                      Trustees
</TABLE>


                                       4