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Spinal Analysis Machine (S.A.M.)

Stephen Barrett, M.D.

S.A.M., the Spinal Analysis Machine, is a twin-scale device that many chiropractors use to detect "postural imbalances." It is said to be useful for initial evaluation of new patients, "public health screenings," health talks, scoliosis detection centers, mall shows, spinal care classes, and patient progress evaluations. The person being tested stands with one foot on each scale while the chiropractor makes various observations about the weight readings and the individual's posture. The difference in weight supposedly enables the chiropractor to establish:

The company marketing the device also provides posters, display booths, and computer software for generating reports. The posters purport to show relationships between leg-length differences, spinal curvature, "subluxations," and poor health. The computer software can generate reports describing the alleged postural imbalances, degree of "scoliosis (spinal curvature)," and a statement that most spines with scoliosis show "subluxation degeneration," which, if untreated, can progress and become irreversible. The spinal curvature is described as "probably the result of leg length deficiency," which the chiropractor can correct.

In 1999, the twin-scale device cost $2,995. for a model that can adjust the patient's posture and $1,795 for a nonadjustble model [2]. But the marketer portrays it as a sound investment. A recent ad, headlined "Let S.A.M. Do Your Banking," depicts a fistful of dollars and states:

Think --10 (only) new patients sent to you from the S.A.M. Machine every 2 weeks. . . . Ten x initial visits @ $150 = $1500. Ten x 12 visits each, more or less, (initial intensive care) @ $35 = $4200. Total so far $5700. There are 22 of these two week periods in the year (assuming that you have 4 weeks holidays and why not.- you've earned them). This amounts to $125,400 annually, assuming that not one of these patients returns for optimal care health care! That's also 2200 new patient visits in 10 year period or $1,254,000.

Now, let's say that only two out of 10 patients will think enough of their health to choose optimal care including regular adjustments at the doctor' discretion. That's 440 regular care patients in that period. Three visits yearly translates to $462,000 in the 10 year period. Add to this the initial, intensive care and you have $1,716,000. Now factor in the referrals, walk ins, emergencies, regular new patients. . . You see what I mean? By "compounding" new patients over a period of time you can have #1 Any type of practice that you would want -- with any amount of cash flow and then after a predetermined period, elect, to "takeit easy(er)" or #2. You can go from strength to strength as many of the "megapractices" have. The point is, You make the call because you are in charge of your future [3].

Use of the S.A.M. device is based on the notion that "apparent differences" in leg lengths can cause spinal curvature and subluxations even though the leg bones are the same length. Chiropractors who subscribe to this notion purport to detect leg-length differences with this device or by observing the position of the feet with the patient lying facedown on an examining table. The company's brochure also claims that 85% of people have "apparent differences" in leg length and suggests that use of the device can attract 20 to 40 new patients per week. The more likely explanation is that such "differences" are caused by slight variations of hip position or of normal spinal muscle tension. In 1993, when I underwent S.A.M. testing in a chiropractor's office, the chiropractor related his observations to spinal curvature and hip rotation (which I do not believe I have) and noted that I tended to carry my head forward (which I do).


  1. Doctor Meet S.A.M.: A Guide for Chiropractic Physicians. Practice Enhancement Catalog #138. Henderson, VA: The S.A.M. Company, 1993.
  2. S.A.M. Web site, accessed Dec 29, 1999.
  3. Let S.A.M. do your banking! Advertisement, The Chiropractic Journal 14(3):4, 1999.

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This article was revised on December 29, 1999.