<PAGE>   1
                                                                 EXHIBIT 10.3.13


                      SECOND AMENDMENT TO LEASE AGREEMENT


         THIS SECOND AMENDMENT TO LEASE AGREEMENT, by and between TWIN TOWERS
INVESTMENT PARTNERSHIP, a Texas General Partnership ("Landlord") and Emergency
Occupational Physicians Services, Inc., d/b/a THE COMPANY DOCTOR, ("Tenant"' as
executed this 18 day of December 1996.

                                  WITNESSETH:

         WHEREAS, Twin Towers Investment Partnership, as Landlord, and The
Company Doctor, as Tenant, have heretofore entered into that certain Office
Building Lease Agreement, dated April 26, 1991, and First Amendment to Lease
Agreement, dated August 1, 1996 (the "Lease"), under and pursuant to the terms
of which Tenant has leased certain office space ("Premises") in that certain
office Building commonly known as "Twin Towers" ("Building"), which is located
at 8585 N.  Stemmons Freeway, in Dallas, Dallas County, Texas, as more
particularly described in the Lease; and

         WHEREAS, Landlord and Tenant desire to amend the Lease and other terms
agreed upon herein;

         NOW, THEREFORE, for and in consideration of the mutual covenants
contained herein and in the Lease, the parties hereby covenant and agree that
the Lease is amended as follows:

         1.      DEFINED TERMS.  Terms defined in the Lease and delineated
herein by initial capital letters shall have the same meaning ascribed thereto
in the Lease, except to the extent that the meaning of such term is
specifically modified by the provisions hereof In addition, other terms not
defined in the Lease but defined herein will, when delineated with initial
capital letters have the meanings ascribed hereto in this Amendment.  Terms and
phrases which are not delineated by initial capital letters shall have the
meanings commonly ascribed thereto.

         2.      EXPANSION OF PREMISES.  The "Premises" shall be amended to
include approximately 2,056 rentable square feet and 1,788 useable square feet,
as described on Exhibit "A" (hereinafter the "Expansion Area") and now being,
part of Suite 107N, whereby the "Premises" is deemed for all purposes to now
contain approximately 8,163 square feet of "Rentable Area", being approximately
6,939 square feet of "Usable Area" effective as of February 1, 1997.

         3.      COMMENCEMENT DATE.  As used herein "Commencement Date" shall
mean February 1, 1997.

         4.      LEASE TERM.  As used herein "Lease Term" shall mean a term
commencing on the Commencement Date, and continuing for sixty (60) full
calendar months.

         5.      BASE RENTAL.  From and after the Commencement Date of February
1, 1997, Paragraph I (c) of the Lease shall be deleted in its entirety and the
following inserted in lieu thereof as Paragraph I (c) :



                                      1
<PAGE>   2
l(c)    "Base Rent" shall mean commencing on the Commencement Date of February
1, 1997 and continuing through and including January 31, 2002 the annual sum of
$118,363.50, being $9,863.62 per month ($14.50 per rentable square foot);

        6.       SECURITY DEPOSIT.  Paragraph l(o shall be deleted in its 
entirety and the following inserted in lieu thereof as Paragraph 1(0:

        l(f      Security Deposit.   "Security Deposit" shall mean the sum of 
        Nine Thousand Eight Hundred Sixty Three Dollars and Sixty Two cents 
        ($9,863.62).

        7.       TENANT IMPROVEMENT ALLOWANCE.  With respect to the "Expansion 
Area", Landlord shall provide to Tenant a "not to exceed" tenant improvement
allowance for above and below ceiling of $15.00 per rsf of expansion area
(2,056 rsf) or $30,840.00 subject to Owner approval of plans and
specifications.

        8.       BROKERAGE FEES AND COMMISSION.  Tenant represents that it has 
dealt with no broker, agent or other person in connection with this Amendment
and that no broker, agent, or other person brought about this Amendment, other
than an agent of the Landlord.  Tenant hereby indemnifies and holds Landlord
harmless against any loss, claim, expense or liability with respect to any
commissions or brokerage fees claimed on account of the execution and/or
renewal of this Lease or expansion of the Premises hereunder, except for agent
of Landlord, if applicable, due to any action of the indemnifying party.

        9.       WHOLE AGREEMENT; EFFECT OF AMENDMENT.  Except as specifically 
amended by the provisions hereof, the terms and provisions hereof, the terms
and provisions in the Lease shall continue to govern the rights and obligations
of the parties thereunder; and all provisions and covenants of the Lease shall
remain in full force and effect as stated therein.  All Amendments and the
Lease are the entire agreements among the parties and shah be construed as one
instrument.  There are no covenants, agreements, representations, warranties or
restrictions between the parties hereto, whether written or oral other than
those specifically set forth in the Lease and this Amendment.  The terms ,
provisions and covenants of this Amendment shall inure to the benefit of and be
binding upon the parties hereto and the respective heirs, successors in
interest and legal representatives.





                                       2
<PAGE>   3

         IN WITNESS WHEREOF, Landlord and Tenant have executed this Amendment
in multiple counterparts as of the day and year first above written.

                                        LANDLORD

                                        Twin Towers Investment Partnership
                                        a Texas General Partnership
                                        
                                        By: Pacific Partners USA, Inc.
                                        a Texas corporation
                                        
                                        By:
                                           -------------------------------------
                                        Its:
                                            ------------------------------------

                                        
                                        TENANT
                                        
                                        Emergency Occupational Physicians
                                        Services, Inc., d/b/a The Company Doctor
                                        
                                        By:
                                           -------------------------------------
                                        Its:
                                            ------------------------------------





                                       3
<PAGE>   4
                                                                 EXHIBIT 10.6.2



                  AMENDMENT TO PRACTICE MANAGEMENT CONSULTING
                         AND CLINIC SERVICES AGREEMENT

         THIS AGREEMENT, is made and entered into, with an effective date of
April 15, 1997, by and between The Company Doctor, a Delaware corporation
("TCD") and The Physician Group, P.A., f/k/a Donald F. Angle, M.D., P.A., a
professional association organized under the laws of the State of Texas ("PA").

                                    RECITALS

         WHEREAS, PA is engaged in the business of providing occupational
medical services and related services to the general public;

         WHEREAS, TCD is engaged in the business of providing management,
marketing, administrative, financial, information, personnel and other related
services to PA;

         WHEREAS, PA and TCD have entered into that certain Practice
Management, Consulting and Clinic Services Agreement dated as of November 1,
1995 ("Practice Management Agreement"), pursuant to which TCD provides certain
services to PA;

         WHEREAS, TCD intends to enter into a Loan and Security Agreement with
HCFP Funding, Inc. ("HCFP") pursuant to which HCFP has agreed to provide
revolving credit financing to TCD that is secured by, among other things,
accounts receivable from the provision of occupational medical services and
related services (the "Accounts");

         WHEREAS, the Practice Management Agreement does not clearly establish
rights to TCD to the Accounts;

         WHEREAS, the fees to be paid to TCD by PA for its services should be
amended based upon TCD's accountant's input, among other things; and

         WHEREAS, in order to reflect the nature of the Accounts and other
matters of concern in the Practice Management Agreement this amendment is of
necessity;

         NOW THEREFORE, in consideration of the premises set forth above and
the terms and conditions contained herein, and other good and valuable
consideration, the sufficiency of which is acknowledged, TCD and PA have agreed
to the following amendments.  Capitalized terms defined in the Practice
Management Agreement which are used herein shall have the same meanings as set
forth in the Practice Management Agreement unless otherwise specified herein.

         A.      The Practice Management, Consulting, and Clinic Services
Agreement is amended as follows:
<PAGE>   5
1)       delete the last sentence of paragraph 1.(d)

2)       delete the last sentence of paragraph 1.(e)

3)       add paragraph 1.(f)(10) as follows:  "any salaries, bonuses or
         benefits payable with respects to P.A.  Physicians;"

4)       delete paragraph 1.(f), the second (2) and replace with the following:
         "any salaries, bonuses, or benefits payable with respect to PA
         employees or contractors except for Physician salaries, bonuses or
         benefits;"

5)       delete paragraph 1.(g) and replace with the following:  "PA Practice
         Expenses shall mean that portion of the Clinic Expenses directly
         attributable to the PA's Practice."

6)       delete paragraph 1.(h) and replace with the following:  "Ancillary
         Expenses shall mean that portion of the Clinic Expenses directly
         attributable to TCD's provision of ancillary services."

7)       delete paragraph 2.1 and replace with the following:  "Locations.  The
         terms and conditions of this Agreement will apply to all Clinics
         hereinafter acquired and operated by TCD or its subsidiaries and
         whereby the PA, or any subsidiary or affiliate of PA, provides medical
         services at any location."

8)       delete the last sentence of paragraph 3.2.

9)       delete the last sentence of paragraph 3.5 and replace with the
         following:  "All revenues beyond those needed to service immediate
         expense and base PA income will be used to repay TCD for start-up
         costs in full before being applied to any distributable net income."
10)      add the following language to the end of paragraph 3.6b.:  "except as
         authorized under Paragraph 12;"

11)      add the following language to the end of paragraph 7.1:  ";however,
         TCD shall make such payments on behalf of PA from Base Clinic
         Revenues.  If Base Clinic Revenues do not equal or exceed PA Clinic
         Expenses TCD shall pay the difference and charge such shortfall to the
         PA to be repaid out of future Net PA Practice Revenue."

12)      add the following language to the end of paragraph 8.2(a):  ", limited
         to the profits of the Practice."
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13)      delete the last sentence of paragraph 8.2(b) and replace with the
         following:  "Accordingly, during each month in which annualized Base
         Clinic Revenue exceed $400,000, PA will pay TCD management fees equal
         to the greater of $10,000 or the sum of twenty-five percent (25%) of
         PA Practice Revenues and thirty percent (30%) of the Net PA Practice
         Revenues accrued during that month limited to the profits of the
         Practice."

14)      delete paragraph 8.3 and replace with the following:  "Marketing and
         Marketing Management.  As compensation for value received from
         centralized marketing and marketing management, TCD will receive each
         month an amount equal to ten percent (10%) of PA Practice Revenues."

15)      delete paragraph 8.4 and replace with the following:  "Unpaid
         Balances.  All unpaid balances due under 8.2(d) and 8.3 herein will be
         carried forward from month to month, and will be paid in full before
         distribution of any net revenues to the PA."

16)      delete paragraph 9.2 and replace with the following:  "PA will retain
         all net PA Practice Revenues less applicable management, marketing and
         other fees and any expenses incurred by TCD on PA's behalf not
         included in PA Practice Expenses, in accordance with the terms of this
         Agreement."

17)      delete paragraph 12 and replace with the following:  "SECURITY FOR TCD
         COMPENSATION.  To provide for the prompt and orderly payment of
         amounts owing from time to time by PA to TCD pursuant to this
         Agreement, and to facilitate TCD in obtaining working capital and
         other corporate loans.  PA hereby assigns to TCD in and consents to
         the pledge by TCD to a third party designated by TCD of, all its
         existing and hereafter created accounts receivable, exclusive of
         Medicare/Medicaid accounts receivable, all cash or non-cash proceeds
         therefrom, all insurance policies and proceeds relating thereto, and
         all of the PA's rights as an unpaid provider of services, whether new
         existing or hereafter created or acquired.  PA agrees to execute, and
         hereby appoints TCD as its attorney-in-fact to execute for PA, any and
         all documents necessary to confirm such assignment or perfect such
         pledge, including but not limited to, UCC financing statements."

B.       Except as specified herein, the Practice Management, Consulting and
Clinic Services Agreement shall remain in full force and effect and is hereby
ratified and confirmed.

C.       This amendment may be executed in counterparts and all counterparts
taken together shall be deemed to constitute one and the same instrument.
<PAGE>   7
         IN WITNESS WHEREOF, the parties have hereunto set their hand effective
as of the date first above written.


THE COMPANY DOCTOR


By: /s/ Donald F. Angle, M.D.              
    ------------------------------
    Its: President                               
         -------------------------

THE PHYSICIAN GROUP, P.A.
f/k/a Donald F. Angle, M.D., P.A.



By: /s/ Donald F. Angle, M.D.          
    ------------------------------
    Its: President                               
         -------------------------


AGREED AS TO TERMS AND CONDITIONS:

NORTHSIDE FAMILY MEDICAL CLINIC            ROBERT G. DUCHOUQUETTE, M.D., P.A.
PROFESSIONAL ASSOCIATION


By: /s/ Donald F. Angle, M.D.              By: /s/ Donald F. Angle, M.D.       
    ------------------------------             --------------------------------
    Its: President                             Its: President
         -------------------------                  ---------------------------
Date:       April 15, 1997                 Date:        April 15, 1997         
     -----------------------------              -------------------------------