Link to Figures Show Figures
	Article Text Figures References
	Send Link Send HTML Article

A Survey of Clinical CAD/CAM Use

Andrew L. Steele, CP

ABSTRACT

Exploring and evaluating a computer-aided design/computer-aided manufacturing (CAD/CAM) system can be an intimidating task, even for the experienced computer user. Two of the biggest obstacles facing contemporary prosthetics are educating and informing the new or prospective CAD/CAM user and implementing the system in an existing clinical setting.

The following article strives to give the new or prospective CAD/CAM user insight through others' experiences. Opinions herein are based on a survey returned by facilities that have undergone the CAD/CAM evaluation and implementation process (see sample of survey at end of article).

Introduction

As technology advances, so should we. Many times, however, as technology takes its leaps and bounds, we are left behind due to lack of understanding, resistance to change or intimidation. Such is the case with computer-aided design/computer aided-manufacturing (CAD/CAM) in prosthetics and orthotics. People argue, "Why change? Why consider a CAD/CAM system when our current methods work just fine?" Simply stated, what is experimental today is frequently the norm tomorrow. It is our professional obligation to keep up-to-date on all technological developments that may give our patients an added advantage. In an article by John W. Michael, CPO, he states, "If we fail to accept and enhance this technology (CAD/CAM), other less-qualified individuals will simply fill the void"(1).

The following article is provided as a tool to guide the clinician through CAD/CAM evaluation. The basic components of CAD/CAM are briefly explained, results of a survey sent to members of the American Academy of Orthotists and Prosthetists' (AAOP) CAD/CAM Society are interpreted, and general suggestions from respondents are included.

CAD/CAM Overview

A CAD/CAM system allows modification of an uncorrected or partially corrected impression on-screen. An online system consists of a minimum of a personal computer and digitizer; a computer numerically controlled (CNC) milling machine and automated vacuum former are optional (2,3). Exceptions are the IPOS System I and System II, which do not incorporate a digitizer. After modifications are made to the computer-generated image, the image is transmitted to the CNC milling machine, where the positive model is carved out of a blank of plaster or rigid foam (2,3,4). Brief explanations of CAD/CAM components and their functions follow.

• Computer. The brain of the system. Assists in executing commands to modify an impression. Allows communication between the user and other system components. Consists of a central processing unit (CPU), keyboard, mouse and monitor.
• Digitizer: Device that duplicates the inside of a negative impression (5) or the outside of a positive model. Sends the compiled information to the computer where the model is depicted three-dimensionally on the computer screen.
• CNC milling machine (or carver). Carves a modified positive model out of a blank made from a plaster/corn starch mixture or rigid foam (2,4).
• Vacuum former: Unit with self-contained heating oven. Automatically vacuum-forms a preformed thermo- plastic cone. Can vacuum-form sockets from a variety of plastics (3).

CAD/CAM components can be purchased separately. A digitizer and personal computer (IBM, IBM-compatible or Apple Macintosh, depending on software preference) are required (6). With the basic set-up, a modem is used to transmit the record of the modified impression to a central fabrication center. The central fabrication site then carves the model and fabricates the prosthesis or orthosis according to the practitioner's particular specifications.

On-site carving and fabrication require a carver, in addition to the computer and digitizer; vacuum former is optional. The standard vacuum-forming process can be used with CAD/ CAM (7).

Methodology

During the preliminary evaluation of CAD/CAM at Newington Children's Hospital, many questions arose about how to most effectively introduce the CAD/CAM system into the clinical setting. It was felt that it would be beneficial to see how other facilities introduced their CAD/CAM systems. A survey of 21 questions was created and sent to .113 members of the AAOP CAD/CAM Society. The survey examined facility size, software, hardware, staff training methods and general opinions of CAD/CAM. Of 113 surveys sent, 34 (30 percent) were returned and 23 were completed. Eleven were returned blank because the facility did not have CAD/CAM or was in the midst of the evaluation process. The results provide a cross-sectional view of systems in use and clinicians' reactions to these systems.

Results

Participants were asked to break down by percentage how their CAD/CAM system was used (e.g., of all sockets produced with CAD/CAM, what percentage are transtibial (below-knee) sockets, what percentage are transfemoral (above-knee) sockets, etc.).Figure 1 shows how the average facility used its CAD/CAM system. Figure 2 depicts what software programs the respondents use.

The average respondent had 2.07 years of experience with CAD/CAM (see Figure 3 ) and has an average of 3.13 prosthetists and 2.26 orthotists on staff (see Figure 4 and Figure 5 ). A clinician certified in both prosthetics and orthotics was counted as a prosthetist and orthotist.

Figure 6 illustrates which company's hardware each facility is using. Those depicted under "Did not specify" use the particular CAD/CAM equipment but did not state which company's products they're using. Two facilities employed two different digitizers; one facility used two different carvers; and yet another company had two different vacuum formers.

This accounts for the totals of the three categories of Figure 6 being 25, 24 and 24 respectively.

Table 1 depicts who operates the carver and thermo former or if it is done at a central fabrication center.

Discussion

Many facilities are concerned their staffs will not have enough computer experience. Nine (39 percent) of the 23 responding facilities had no one on staff with computer experience. Seventeen facilities (74 percent) allowed all the clinicians to begin learning and using the CAD/CAM package at the same time. Equally important is who will run the CNC milling machine (carver) and vacuum former if one is purchased (see Table 1 ).

The participants were asked how they trained their staffs and were given four choices. Choices follow with number of selections in brackets:

• One clinician was required to learn the package and teach others. [6]
• A professional from a CAD/CAM distributor instructed the clinicians. [18]
• Clinicians were required to learn the package on their own without any formal training. [8]
• Initially, a select group of clinicians learned the package and then taught other clinicians. [5]

Participants were allowed to select all choices that applied to their situation. Therefore, many chose a combination of the above. When asked whether they would change anything in the learning process to make it easier or more efficient, several responses were given.

• The initial CAD/CAM training approach used at a facility should be more structured, and CAD/CAM software should be explained fully.
• Distributors should produce better tutorials and printed manuals for their software packages and hardware.
• Time should be spent with a CAD/ CAM-experienced prosthetist/orthotist.
• Distributors need to make the hardware more user-friendly and reliable.
• A facility should be selective in the patients it chooses initially. Early success yields confidence and motivation.

Survey respondents recommended the following to facilities undergoing the CAD/CAM evaluation and implementation process:

• Purchase only the computer, digitizer and software. It is important initially to gain familiarity with the software and digitizer. Let a central fabrication center do the carving.
• After staff is familiar with the computer, digitizer and software, then evaluate and implement the carver and/or vacuum former.
• Map out a plan for implementation and follow that plan.
• Dedicate yourself and your company to learning the system early.

A number of clinical advantages are associated with CAD/CAM. The most frequently noted was the ability to recall shapes and consistently repeat exact modifications, which allows for more accurate fittings as well as improved evaluation of check sockets. Respondents also believed CAD/CAM enhanced record keeping.

Because CAD/CAM is state-of-the art technology, do not overlook its use as a marketing tool. Many of the participants stated it allowed them to focus more on their clinical skills and saw CAD/CAM as an excellent instructional tool.

A final advantage is the ability to use CAD/CAM in remote locations or satellite offices. Sixteen (70 percent) of the 23 facilities stated they had satellite offices. Of those 16. eight use CAD/ CAM in their satellite offices.

Time and money savings follow as clinicians gain proficiency with the software, according to respondents. Twelve (52 percent) of the facilities are able to get an appropriately fitting socket on their initial check socket, eight (35 percent) need two check sockets, while only three (13 percent) need three check sockets or more. Recently, Ruber found in his study of patients fitted with temporary, transtibial, CAD/CAM sockets that 67 percent required at least one additional attempt (5). Kohler, Lindh and Netz studied the difference in comfort between transtibial prosthetic sockets made by CAD/CAM and those made by hand. They could find no difference between the two techniques, provided two CAD/CAM attempts were allowed (8). When asked if the system saved time and/or money, responses were as follows:

• No one said it saved only money.
• Four (17 percent) said it saved only time.
• Nine (39 percent) said it saved both time and money.
• Ten (43 percent) said it saved neither time nor money.

In a study by Holden and Fernie, no relationship was found between the amount of time taken on the computer and the success of the CAD/CAM socket fit (9).

The above statistics relating to time and/or money savings are somewhat inconclusive; however, the general consensus was to look more for long-term cost savings. Most likely a significant difference will not be seen immediately due to the learning curve, but the more dedicated one is to learning the system, the earlier cost/time benefits will be seen.

Conclusion

When considering implementing a CAD/CAM system, set a plan to follow and be patient; be willing to spend the time to evaluate and implement the system. Use this important period of time to decide who will use the system first and who will be in charge. To further simplify the process, it may be a good idea to have a single person act as the liaison between the CAD/CAM distributor and your facility. To have a successful experience, a facility must dedicate itself to learning and using the CAD/CAM system.

Other important tips expressed in the surveys were: Know the limits, capabilities and requirements for your desired personal computer and CAD/ CAM hardware and software. Experiment with each software and hardware package in a fully operational clinical setting, if possible. Only four (17 percent) of the 23 responding evaluated only the software they are using currently. Most CAD/CAM distributors are happy to give a full demonstration. And finally, make sure there is enough room to grow, and the system will be sophisticated enough for use in the next two or three years.

Acknowledgements

The author wishes to thank Algis Maciunas, CPO, Robert Lin, CPO and James Fezio, CO, for their guidance during this research project at Newington Children's Hospital, Newington, Conn. Thank you also to Marie Salter and Gerald Stark for their editorial input.

ANDREW L. STEELE, CP, is a staff prosthetist/orthotist for Dale Clark Prosthetics Inc., in Waterloo, Iowa. This article resulted from a research project done at Newington Children's Hospital, Newington, Conn., while Steele was in its prosthetic residency program in 1992.

References:

1. Michael JW. Reflections on CAD/CAM in prosthetics and orthotics. JPO 1989; 1:5:116-2 1.
2. Saunders CG, Foort 1, Bannon M, Lean D, Panych L. Computer-aided design of prosthetic sockets for below-knee amputees. Prosthetics and Orthotics International 1985:9:17-22.
3. Davies RM, Lawrence RB, Routledge PE, Knox W. The Rapidform process for automated thermoplastic socket production. Prosthetics and Orthotics International 1985;9:27-30.
4. Engsberg JR,Clynch GS, Lee AG, Allan is, Harder JA. A CAD/CAM method for custom below-knee sockets. Prosthetics and Orthotics International 1992; 16:183-8.
5. Ruder GK. CAD/CAM transtibial temporary prosthesis: analysis and comparison with an established technique. Prosthetics and Orthotics International 1992:16:189-95.
6. Lemaire ED. Distance education technology for prosthetic CAD/CAM instruction. JPO 1993;5:3:82-7
7. Bowker JH, Michael JW. Atlas of limb prosthetics: surgical, prosthetic and rehabilitation principles. 2nd ed. St. Louis: Mosby Year Book, 1992;71-3.
8. Kohler P, Lindh L, Netz P. Comparison of CAD/CAM and handmade sockets for PTB prostheses. Prosthetics and Orthotics International 1989; 13:19-24.
9. 1-Jolden JM, Fernie GR. Results of the pilot phase of a clinical evaluation of computer-aided design of transtibial prosthesis sockets. Prosthetics and Orthotics International 1986;lO:142-8.