Thursday February 22, 1996

Kappa Delta, OREF honor research

Orthopaedic researchers will be honored Thursday, Feb. 22 with the presentation of the 1996 Kappa Delta Awards and the first Orthopaedic Research and Education Foundation (OREF) Clinical Research Award.

The presentations and summaries of the papers for the Kappa Delta Awards and the OREF Clinical Research Award will be held at 1 p.m. in the Ballroom of the Georgia World Congress Center. The papers will be presented in their entirety at the Orthopaedic Research Society meeting at 10:30 a.m. on Thursday, Feb. 22 in the Hyatt Regency Atlanta hotel.

The Kappa Delta Sorority's Ann Doner Vaughn Award will be presented to Malcolm H. Pope, Dr MedSc, PhD, for a comprehensive study of the cause and effect relationship between whole body vibration from driving vehicles and career drivers' low back pain. The co-authors of the paper, "Low Back Pain and Whole Body Vibration" are Marianne Magnusson, PT, Dr MedSc; and David G. Wilder, PhD.

When the researchers compared bus drivers and truck drivers from the United States and Sweden with sedentary individuals, they found that "career vibration exposure was related to low back, neck, and shoulder pain."

The United States' truck drivers had the highest vibration exposure, did moderate lifting on the job, exercised only minimally, were overweight, and more than half smoked. Despite these potential negatives, only 50 percent of the drivers had suffered from low back pain recently, reported Dr. Pope, Distinguished Professor in the University of Iowa biomedical engineering department and director of the Iowa Spine Research Center. Yet, only 24 percent missed work, which he attributed to this group's "l00 percent job enjoyment.

While several factors may cause low back pain, disability due to low back pain is more dependent on whether the worker really wants to go to work," he said.

Using sophisticated electromyographic instrumentation, the researchers confirmed that sitting subjects' lumbar and thoracic muscles became fatigued after being exposed to whole body vibration from their vehicles. After compiling information on spinal height changes, the researchers documented that the individuals' spinal height decreased when they were sitting without vibrations and when they were sitting and exposed to whole body vibrations. "The sitting posture, in itself, always caused height loss in the subjects, provided that the sitting exposure was preceded by a less loading activity," Dr. Pope said.

Adding inclined backrests (110 and 120 degrees) "reduced the load on the spine and the effects of vibration," noted Dr. Pope, who recommends a renewed emphasis on seat designs and seat materials that can prevent the harmful effects of vibration.

"Vibration also probably combines with other risk factors such as lifting, pushing, and pulling to increase the risk" of low back pain, reported Dr. Pope. After individuals are exposed to whole body vibration, their muscles are tired and the spinal discs have become compressed which means they have less ability to absorb and distribute the load. This means that a driver should probably avoid heavy lifting after driving a vehicle to avoid an injury, he cautioned.

Kathryn G. Vogel, PhD, a professor in the department of biology at the University of New Mexico, Albuquerque, will receive the Elizabeth Winston Lanier Award for basic research on the musculoskeletal system. Co-authors of the paper, "What Proteoglycan Content Says about the Mechanical History of Tendon," are Stephen P. Evanko, PhD, University of Washington, Seattle; and James R. Robbins, PhD, University of New Mexico.

In a series of experiments using bovine and human tendons, the researchers analyzed fibrocartilage in tendons, concentrating on the proteoglycan content and what it says about the mechanical history of the specific tendons. "It is our hope that understanding the capacity of tissues to modify the structural and material properties of their extracellular matrix will allow clinicians to recognize more effectively why certain tissues are found where they are and better assure that they are not induced inappropriately," said Dr. Vogel.

She and her colleagues believe that the development of fibrocartilage in tendon usually occurs as a result of a normal and appropriate cellular response to mechanical loads that include hydrostatic pressure and shear. Their study focused on the ability of tendon cells to modify the composition and organization of the tendon matrix and to form fibrocartilage when the tissue is subjected to altered mechanical loads.

The researchers' analysis of adult and fetal bovine tendons documented that tendons that are subjected only to tension contain "very little glycosaminoglycan which is associated with a small, collagen-bound proteoglycan called decorin." However, where this tendon is wrapped around a foot bone, a fibrocartilaginous tissue develops that contains 10-fold higher amounts of glycosaminoglycan that is primarily associated with the proteoglycan called aggrecan.

In laboratory experiments, researchers applied compressive loads to tendon from fetal bovine tendon and determined that "mechanical compression can regulate synthesis of distinct proteoglycan types in tendon." Dr. Vogel said this basically confirms that the mechanical loading "stimulates synthesis of aggrecan and biglycan, confirming that mechanical stimulation can direct gene expression and proteoglycan synthesis toward fibrocartilage formation."

To test whether the proteoglycan content of a human tendon changes when the tissue is "subjected to different mechanical environments," researchers analyzed autopsy specimens of human rotator cuff tendons from the shoulder joint, comparing the glycosaminoglycan content in those with that found in two regions of biceps tendons from the same shoulders. The glycosaminoglycan content of the rotator cuff tendons was similar and also higher than that found in the tensional region of the biceps tendon.

Jon J. P. Warner, MD, director of the shoulder service at the University of Pittsburgh Center for Sports Medicine, submitted the winning paper for the Kappa Delta Young Investigator Award. Co-authors of the paper entitled, "A Dynamic Model for Motion and Stability of the Glenohumeral Joint," are Richard E. Debski, MS, and Freddie H. Fu, MD. They were honored for developing a dynamic model that enables researchers to simulate the motion and stability of the shoulder joint so they can study the interaction of static and dynamic soft tissues that restrain and stabilize this joint.

The Pittsburgh Dynamic Shoulder Testing Apparatus consists of six computer-controlled servo-actuated hydraulic cylinders that apply force and displacement to "each of the rotator cuff tendons and the middle deltoid through a tendon clamp-cable-pulley system," reported Dr. Warner.

"Our goal has been to develop an accurate and clinically relevant in vitro model of shoulder motion," said Dr. Warner.

Using the experimental design, Dr. Warner and colleagues analyzed the role of the rotator cuff and deltoid muscles during shoulder motion in a normal shoulder and a shoulder with a simulated rotator cuff tear. They then defined the functional anatomy of shoulder glenohumeral ligaments during simulated rotator cuff contraction. Experiments were conducted on fresh frozen cadaver upper extremities. They found that, through compensation of the remaining rotator cuff tendons, normal shoulder kinematics and full abduction were possible even in the setting of a massive rotator cuff tear. They also determined that the glenohumeral ligaments lax throughout most ranges of motion, elongating only at the end ranges. "These findings have direct clinical application to the diagnosis, as well as the operative and nonoperative treatment, of rotator cuff disease and glenohumeral joint instability," said Dr. Warner.

The OREF Clinical Research Award winning paper, "A Ten-Year Prospective Outcome Study of the ACL-Injured Patient," was submitted by the late Dale M. Daniel, MD; Donald C. Fithian, MD; Mary Lou Stone, RPT; Barbara E. Dobson, LVN; William F. Luetzow, MD; and Kenton R. Kaufman, PhD. The late Dr. Daniel devoted his professional career to the development of improved clinical tools for assessing knee-injured patients. The paper represents a body of work which began in 1981, and reports several important findings.

The paper demonstrates the clinical usefulness of instrumented testing of the injured knee. The authors noted that ligament arthrometry was accurate in diagnosing anterior cruciate ligament (ACL) injury when compared against direct arthroscopic visualization. Stability grade as assessed by instrumented testing during the early phase was highly predictive of stability grade during the late phase of the study in patients who did not undergo reconstruction. Furthermore, injured-minus-normal displacement difference with manual maximum force was useful in assessment of the risk of later surgery. "We recommend routine use of ligament arthrometry in the evaluation and counseling of patients following knee trauma," said Dr. Fithian, who is affiliated with Kaiser Permanente Medical Center, San Diego, Calif.

The authors followed a single cohort of patients over more than a decade in order to assess levels of function, symptoms, joint laxity and arthrosis at long-term follow up. The study points out that many patients can function well despite ACL insufficiency. The authors observed that ligament surgery was not effective in preventing several unfavorable outcomes, such as frequency of pain and swelling. They further stated that it is not realistic to expect that patients who undergo ligament reconstruction will be more active five and 10 years after injury than patients with unstable knees who do not undergo reconstruction.

The authors noted that X-ray evidence of arthritis was less pronounced than earlier published reports have suggested, and that ligament reconstruction was not effective at preventing the rather mild degree of joint arthrosis which developed after ACL rupture in most patients. Patients who had partial meniscectomy during the study had more degenerative X-ray changes at follow-up evaluation than those who did not have meniscectomy. "The association of meniscectomy with joint arthrosis, and the ability of ligament reconstruction to reduce the frequency of subsequent meniscectomy, are major issues for the surgeon treating an ACL-injured patient," stated Dr. Fithian.

The risk of later surgery (for meniscectomy or ligament reconstruction) in patients who did not undergo early reconstruction was related to two important factors: preinjury sports participation and the degree of instability. "We interpret the Surgical Risk Factor (SURF) as a function of time spent in activities which place the knee at risk for subluxation, and the magnitude of displacement during a subluxation episode," said Dr. Fithian. The authors observed that ligament reconstruction was effective in reducing the magnitude of the instability and that later surgery was less common when reconstruction was performed. They recommend early reconstruction in patients who are considered at high risk for later surgery, and conservative treatment of patients who are at low risk of subsequent surgery.

The typical ACL injury occurred in young, well-conditioned athletes who tore their ligaments while skiing, playing football, basketball, or volleyball, or other sports activities. This stabilizing knee joint ligament attaches to the front of the tibia and extends upward and backward through the knee joint to the femur.

Since 1921, Kappa Delta's major philanthropic interest has been aid to children affected by crippling disease and birth defects. Kappa Delta has been working with the Academy since 1947 to support orthopaedic research.

The first OREF Clinical Research Award is being presented in recognition of outstanding clinical research related to musculoskeletal disease or injury. Nine outstanding manuscripts were submitted for the award, said Roby C. Thompson Jr., MD, OREF Vice President of Grants and Chairman of the OREF Peer Review Committee. Other members of the peer review committee are Ramon Gustilo, MD; John Roberts, MD; Clement B. Sledge, MD; and James Urbaniak, MD.

http://www.aaos.org/about/papers/ethics/1204eth.asp
1996 Academy News Index

Last modified 20/November/1997