This entry is adapted from a talk presented by Physical Therapy of Los Gatos principal Rob Naber at the Western Occupational Health Conference 2005, held September, 2005 in Monterey, California:

Active Range of Motion (AROM) refers to the range of motion for a specific movement that a patient can achieve without assistance, such as a measurement of how far the back moves when a patient bends forward to touch his or her toes. The distance or angle between the starting and finishing position is the AROM. A reduction in AROM can impair routine, vocational, and athletic movements and overall functional capability. Restoring AROM following injury, surgery, or the effects of an illness on the musculoskeletal system is often the goal of physical therapy and the principal reason that many patients are referred to physical therapy.

In the past, physical therapists used goniometers to quantify lumbar AROM. Though practical for AROM measurements around knees and shoulders, the goniometer was of of very limited clinical utility as a means of measuring motions of the spine and surrounding joints. Other tools and methods, such as flexible rulers and measuring tapes, suffered from a lack of precision and reference values, and were also of little diagnostic value.

In 1984, Mayer, et al. proposed a method using specific inclinometer measurements to enable quantification of lumbar forward bending AROM and discrimination between the contributions of the hip and spine to the overall motion. In 1986, Keeley, et al. published a follow-up article that validated the reliability of the inclinometer-based technique and presented the reference values needed to make measurements made in the clinic meaningful.

While necessary as components of a complete evaluation, individual inclinometer measurements of lumbar AROM offer little information of clinical value and should not be used to report degrees of impairment. Multiple inclinometer measurements are necessary to determine the effects of the patient’s starting posture and the relative contributions of hip, pelvis, and lumbar joints to forward and backward bending. A patient can present with a normal lumbar AROM but still suffer from a “weak back” and recurring back pain and disability.

Physical therapy to restore a diminished lumbar AROM is not simply a matter of achieving a specific AROM value. A more nuanced therapeutic goal of restoring ideal ratios between the contributions of involved joints to composite lumbar motions will lead to more rapid and sustained reductions in impairment and more complete and satisfying recoveries.

Lumbar Spine Active Range of Motion: Significance and Relevance in Rehabilitation presentation by Rob Naber to the Western Occupational Health Conference 2005
Western Occupational Health Conference 2005: New Horizons in Occupational Medicine

An unintended consequence of the increase in sports participation by girls and young women over the past thirty years has been an extraordinary rise in the incidence of anterior cruciate ligament (ACL) injuries in young female athletes. At the college level, one in ten young female athletes participating in sports such as soccer, volleyball, and basketball will suffer an ACL tear injury. These girls are typically unable to practice or compete for one or more seasons and face potential loss of scholarship funding and significant psychological trauma. A widely cited 1985 study found that at the high school level, the knee injury rate among female athletes is one per 100 participants, and noted the need for preventative measures.

In 1983, sports medicine researchers determined that four-fifths of ACL injuries are non-contact injuries, that is, they are caused by the athlete’s own motions rather than collisions with other players. To the researchers, this finding meant that the high incidence of ACL tear injuries in young female athletes might be greatly reduced if those motions could be identified and avoided.

The ACL is one of four major ligaments that connect the upper and lower leg at the knee. The ACL provides joint stability and supports cutting and pivoting motions. Oftentimes, the ACL will tear with a “pop” that can be heard by spectators and other players. Pain and immediate swelling follow. ACL tears require surgical reconstruction using tendon grafts from other areas of the knee or from cadavers, followed by a long period of rehabilitation.

The frequency and seriousness of ACL tears in young female athletes has led to research studies aimed at understanding the problem. These studies are now yielding valuable data. Three major hypotheses to account for the higher number of ACL tears in female athletes versus male athletes have been examined: hormonal differences causing laxity of the female athlete’s ACL, a smaller and more narrow space within the knee for the female athlete’s ACL, and sex-based differences in lower extremity strength and coordination. The last of these three hypotheses is receiving the most scientific support from study data.

Certain aspects of lower extremity strength and coordination can be captured and measured by videotaping athletes while they perform athletic movements in the research lab. While video recordings do not capture complex three-dimensional movements and the rotational stresses that these movements place upon the knees, the recordings do enable researchers to make close measurements of joint and limb positions in a single plane. These measurements were found to have predictive value.

In one well-designed study of 205 young female athletes, researchers found that athletes with a specific way of posturing their lower extremities, known as “valgus” (or “knock-kneed”) alignment, during certain athletic movements were more likely to suffer ACL injury than athletes with more “neutral” or straighter lower extremity alignment. This valgus alignment can be seen by analyzing the angles formed between the ankles, knees, and hips when the athlete lands from a jump off a small box and when she jumps vertically from a crouched position. A separate study that included videographic analysis of 325 young female athletes showed that a six-week neuromuscular training program corrected the lower limb valgus alignment associated with injury during jump landing and takeoff.

It is already well-known to physical therapists that muscular strength stabilizes the knee by helping to maintain the correct relative positions of knee structures during sports movements and by allowing muscles in the legs to absorb forces that would otherwise subject the joint to potential injury. But physical therapists treating young female athletes must now consider the implications of the new studies. Physical therapists familiar with these studies infer that rehabilitation from ACL injury should, in addition to conventional strength training treatment methods, include specific neuromuscular training aimed at improving the athlete’s ability to avoid valgus alignment of the lower extremities during high-risk sports.

It is no longer acceptable to reconstruct the ACL but leave neuromuscular control deficient.

The jump strength training program at Physical Therapy of Los Gatos is an element of rehabilitation from surgical reconstruction of the ACL as well as a standalone performance improvement module. The program includes jump analysis, strength conditioning, and neuromuscular training designed to improve power and acceleration. The neuromuscular training methods employed include visual, auditory and proprioceptive cues to train athletes to use muscular strength to absorb jump impacts in a controlled fashion, and, if necessary, to correct jumping, landing, and pivoting techniques in order to avoid forces associated with injury. For additional information about prevention of ACL injury, rehabilitation from surgical ACL repair, and jump strength performance training for athletes, please call Physical Therapy of Los Gatos at (408) 358-6505.

The role of a physical therapist is to help you regain your function and allow you to return to your life of work, recreation, and other daily activities. A key element of this role is determining whether you have the appropriate range of motion (ROM) available to accomplish your daily activities without pain. Until recently, physical therapists used a device known as a goniometer to measure this range of motion at a joint. Now, physical therapists measure ROM in a different way. This change was brought about by studies showing ROM measurements made using a new tool, known as an inclinometer, are more accurate, precise, and reproducible than measurements made using goniometers. According to the American Medical Association’s Guides to the Evaluation of Permanent Impairment (Third Edition), the inclinometer has been adopted to measure spinal ROM. Physical therapists have also found that inclinometers are easier to use, and provide new and more useful information.

Old School
A goniometer looks a bit like a protractor you may have used to measure angles in geometry class, but with arms, like the type of compass used for drawing circles. The arms of a goniometer intersect at a single axis or pin:

To measure the ROM at a joint with a goniometer, the patient moves his or her body part to the position directed by the therapist (i.e bend your knee). The therapist aligns the arms of the goniometer with the bones surrounding the joint and aligns the pin with the joint axis. Because the therapist cannot hold the goniometer directly against the bones, bone and joint axis positions must be estimated. The angle indicated by the goniometer is recorded. Goniometer measurements typically require the joint to be moved from the beginning of its range to the end of its range of motion. For example in the knee, a measurement is taken when the joint is fully bent and then again when it is fully straightened . Because the positions of the bones and axis points must be estimated, each reading made with a goniometer introduces error into the measurement. Normal joint mechanics introduce another source of error into goniometer measurements: unlike a door hinge rotating around a cylindrical pin, a joint rotates around the ends of the bones, which are not perfectly round. Therefore the joint axis itself moves, making the estimation of the axis position more difficult.

New School
No such estimates or alignments are necessary with an inclinometer. Inclinometers have dials or digital readouts that display the angle at which the inclinometer is situated relative to the line of gravity.



To use an inclinometer, the therapist holds the instrument on the patient, who begins in a standard starting position. The therapist zeroes-out the inclinometer and then instructs the patient to bend the joint through its ROM. The inclinometer’s final reading is the ROM measurement. The inclinometer never leaves contact with the patient and the axis does not need to be identified.

The accuracy of ROM measurements taken using inclinometers can be estimated by comparing their measurements with those taken from X-rays, which allow very direct joint angle measurements. Mayer et al. showed ROM measurements of the spine made using inclinometers are statistically similar to readings determined using X-rays. Keeley et al. showed repeated ROM measurements made using inclinometers yield very reliable values.

Unlike goniometers, inclinometers can be used in pairs to gain even more diagnostic information during patient evaluations. For instance, bending forward to touch the toes is a “composite” motion, that is, some of the motion comes from the hips and some comes from the lower back. When a patient has pain upon bending forward, the physical therapist can use two inclinometers at once to determine whether the lower back and hips are each contributing the proper amount of flexibility to support the movement. The inclinometer readings may indicate that the painful lower back is compensating for the inflexible hips. The therapist can then begin an effective course of physical therapy to relieve the lower back pain by restoring the patient’s hip function and flexibility.

To learn more about inclinometers or see how your spinal range of motion measures up, contact Physical Therapy of Los Gatos at (408) 358-6505.