Chronic repetitive trauma: a cause of atypical degenerative joint disease

Miscellaneous conditions about the elbow in athletes

This article reviews some of the conditions about the elbow in athletes or active individuals. The conditions discussed are synovial plica of elbow, radiocapitellar arthritis, congenital dislocation of the radial head, radio-ulnar synostosis, hemophilia and rheumatoid arthritis. In the past, people who had these conditions were instructed to avoid athletic activities; however, they are now being counseled to remain active and to try to exercise on a regular basis.

Hazard of deceptive advertising of athletic footwear

OBJECTIVES

Athletic footwear are associated with frequent injury that are thought to result from repetitive impact. No scientific data suggest they protect well. Expensive athletic shoes are deceptively advertised to safeguard well through "cushioning impact", yet account for 123% greater injury frequency than the cheapest ones. This study tested the hypothesis that deceptive advertising creates a false sense of security with users of expensive athletic shoes, inducing attenuation of impact moderating behaviour, increased impact, and injury.

METHODS

Fifteen young healthy male volunteers confronted four surfaces: a bare force moment platform, and three with this platform covered by identical shoe sole material made to appear different and advertised divergently. Advertising messages suggested superior impact absorption and protection (deceptive message), poor impact absorption and high injury risk (warning message), and unknown impact absorption and safety (neutral message). Ground reaction forces were recorded for 10 barefoot footfalls, according to a protocol requiring stepping forward from perch to a surface 4.5 cm below.

RESULTS

Impact varied as a function of advertising message (p < 0.001). Deceptive message equalled neutral message in eliciting higher impact than the warning message and the bare platform. Differences grew with repetitions (p < 0.001).

CONCLUSIONS

These data provide a plausible mechanism explaining higher injury frequency in users of expensive athletic shoes. This is the first report to suggest: (1) deceptive advertising of protective devices may represent a public health hazard and may have to be eliminated presumably through regulation; (2) a tendency in humans to be less cautious when using new devices of unknown benefit because of overly positive attitudes associated with new technology and novel devices.

Balance and vertical impact in sports: role of shoe sole materials

OBJECTIVE

Athletic shoes and mats are support surface interfaces composed of relatively soft compressible materials designed to protect against injuries occurring in sports through force of vertical impact. Impact remains high with their use because humans land harder with them. We hypothesize that this hard-landing strategy is an attempt by the user to improve stability, by compressing the material to a less destabilizing thinner-stiff variety. We tested this hypothesis by comparing impact and balance on materials consisting of ethyl-vinyl acetate (EVA) foams of varying stiffness, identical to that found in soles of athletic footwear.

DESIGN

Randomized-order, crossover trial, controlled comparison, blinded.

SETTING

Volunteers were selected from the general community.

PARTICIPANTS

A random sample of 12 healthy men from the general population (mean age 30 years, SD +/- 6). Additional selection criteria were absence of disabilities influencing ability to walk, run, and balance, and no history of frequent falls.

METHODS

Impact testing and stability measures were performed on the same test day. Ground reaction forces were measured for ten barefoot footfalls. The protocol required stepping forward from perch to surface 4.5 cm below. Stability testing was performed with one-legged standing consisting of placing left foot on top of right for 30 sec, barefoot, eyes open, and gaze straight, with arms to side. Subjects confronted four surface conditions presented in random order: a bare rigid platform, and the platform covered with one of three 2.5-cm-thick materials.

RESULTS

Steady state vertical impact was a negative function of interface stiffness, with the softest interface producing the greatest vertical impact, and the stiffest interface the least vertical impact. Vertical impact and stability measures were also negatively related, with the strongest correlation obtained with the softest interface (r = -.87, p < .001). No relation between these variables was obtained for the rigid surface.

CONCLUSION

Balance and vertical impact are closely related. This supports the hypothesis that landing hard on soft surfaces is an attempt to transform the interface into a form associated with improved stability. According to these findings, currently available sports shoes and mats are too soft and thick, and should be redesigned to protect the persons using them.

Scanning electron-microscopic and magnetic resonance-imaging studies of injuries to the patellofemoral joint after acute transarticular loading

To examine the effects of transarticular loading on articular cartilage and subchondral bone, we used a canine model that we had developed previously, in which a standardized load of approximately 2000 newtons is delivered across the patellofemoral joint. The purpose of the study was to define and describe the initial changes, as seen on histopathological and magnetic resonance-imaging studies, that occur in the early stages after injury to the joint by transarticular loading. Scanning electron microscopy was used to define the extent and characteristics of the fractures produced in the subchondral bone of four patellae that were examined on the day of loading. We found multiple, extensive fractures through the zone of calcified cartilage and the subchondral bone, frequently with step-off displacement, and with little or no change in the gross appearance of the articular cartilage. Specimens from four patellae were examined histologically two weeks after loading, and the observed changes were correlated with those that had been demonstrated by scanning electron microscopy. Fractures through the zone of calcified cartilage and the subchondral bone, with step-off displacement, were prominent. Clefts were present in the surface of the articular cartilage and, in some areas, there was a focal loss of proteoglycan from the extracellular matrix, as indicated by the complete absence of staining with safranin O. Six dogs were examined one year after loading. There was healing of the subchondral fractures and restoration of proteoglycan in the extracellular matrix. However, superficial clefts and fissures were still present in the articular cartilage. Sequential magnetic resonance-imaging studies were also carried out on these six dogs, at two, eight, sixteen, thirty-six, and fifty-two weeks after loading. Two weeks after loading, all knees had soft-tissue swelling, effusion, and a decreased marrow signal in the medullary cavity of the patella. The decreased marrow signal and effusion were still present eight weeks after the impact, and then the findings gradually returned to normal. One year after loading, it was found that the histopathological changes had not been progressive; in fact, they had been ameliorated and, to some extent, reversed by repair processes. The early, severe magnetic resonance-imaging changes had also been reversed, so that this study demonstrated normal findings by one year after loading.

Subchondral damage after acute transarticular loading: an in vitro model of joint injury

Intact canine metacarpophalangeal and metatarsophalangeal joints were subjected to a variety of loads in vitro. Intraarticular fracture occurred in 19 joints loaded to an average force of 2.4 +/- 0.4 kN with a corresponding loading rate of 88 +/- 23 kN/s. The remaining 29 joints were without gross evidence of fracture with an average load and loading rate of 1.7 +/- 0.9 kN and 64 +/- 32 kN/s, respectively. In the fractured specimens, damage to the zone of calcified cartilage and subchondral bone was much more extensive than was initially evident by gross inspection when assessed by scanning electron microscopy. Cracks with associated step-off displacement at the zone of calcified cartilage were found distant to the gross fractures. These findings were confirmed histologically. In addition, cracks localized to the zone of calcified cartilage were commonly identified histologically in specimens loaded in the range of 1.9-2.8 kN, but were not grossly fractured. The contact area determined with pressure-sensitive film increased with increasing load up to the point of fracture. The average pressure generated at the articular cartilage surface at the time of fracture in this model is > or = 40 MPa, and the fracture occurred at the contact site. Our findings suggest that failure in acute transarticular loading begins in the zone of calcified cartilage and subsequently involves the subchondral bone and overlying cartilage. This type of injury may contribute to the development of osteoarthritis after intraarticular fracture, or at high loads that do not result in gross fracture.

Primary osteoarthritis of the elbow

Sixteen patients (14 male, two female; mean age 61, range 49-75 years) with elbow osteoarthritis (OA) unassociated with nodal or crystal related OA were studied. None had received obvious trauma. The dominant elbow was affected in 14, the other in 12 (mean symptom onset in these 26 elbows 53 years (range 31-63), mean symptom duration 7 year (range 1-20]. Joint fluids (six patients) were non-inflammatory: biopsy (two) showed non-specific synovitis. Radiographic changes occurred in humeroulnar (25/26, 96%), humeroradial (100%), and radioulnar (22/26, 85%) compartments: uniform narrowing with hypertrophic change predominated and osseous bodies were common (18/26, 69%). Thirteen had OA elsewhere, notably 2nd/3rd metacarpophalangeal joints (10/16, 62%), knees (6/16, 38%), and hips (5/16, 31%). A good clinical outcome was observed in 22/26 elbows. In our experience symptomatic 'primary' OA of the elbow particularly affects middle aged men, commonly associate with metacarpophalangeal OA ('Missouri metacarpal syndrome'), and has a favourable outcome. Contrary to previous reports a major role for trauma is difficult to substantiate.

Assessment of nerve damage in the feet of long-distance runners

To answer the question, "Does long-distance running injure nerves of the feet and legs?" we invited the 25 members of the Rochester Track Club who had run the greatest number of miles in their lifetime to participate in a study that involved neurologic examination, determination of detection thresholds of touch-pressure, vibratory, and cooling sensations of the foot, and evaluation of nerve conduction. None of the runners had clinical symptoms or signs of peripheral neuropathy. Most of them reported having had toe and foot injuries, sometimes associated with short-lived sensory symptoms. A computer-assisted sensory evaluation of the detection threshold for vibratory sensation of the toe revealed slightly, but significantly, higher values in the runners in comparison with age- and sex-matched control subjects. Similarly, small, but statistically significant, differences were also observed for some attributes of nerve conduction in the leg and foot nerves of the runners. These results suggest that long-distance running causes multiple small injuries to the toes and feet, which lead to measurable differences in the detection threshold for vibratory sensation and in nerve conduction but not to overt neuropathy. The trivial subclinical neuropathic deficits we noted are readily offset by the assumed health and recreational benefits of running.

Pathologic conditions of the pisiform and pisotriquetral joint

In eight of sixteen patients with symptomatic pisotriquetral joints the pisiform was excised. A detailed study allowed correlation of the etiologic factors with the pathologic diagnosis. In a similar fashion pathologic-etiologic data were retrieved from 216 cases identified from the world literature and organized into the following four pathologic groups: primary OA (2.3%), secondary OA (48.4%), other arthritides (4.7%), and flexor carpi ulnaris enthesopathy (44.6%). The most common causes were acute and chronic trauma and instability. On the basis of these data, we hypothesized that loss of integrity to the surrounding retinacular structures of the pisiform may lead to instability and thus dysfunction of the joint.

Unusual metacarpophalangeal osteoarthritis in a jackhammer operator

Severe, atypical osteoarthritis of the metacarpophalangeal and elbow joints in a jackhammer operator is reported. Articular tissue resected at surgery demonstrated gross fibrillation and histologic evidence of calcification of articular cartilage, and multiple, bony fragments embedded in the synovium. Operation of a pneumatic drill may accentuate a tendency toward development of osteoarthritis in workers who are predisposed to the disease and may also cause it to localize at unusual sites such as the elbow, shoulder, wrist, and metacarpophalangeal joints.

Chronic repetitive unrecognized flexion injury of the cervical spine (high jumper's neck)

Unrecognized flexion injuries of the cervical spine may lead to late instability and neurologic damage. These hidden flexion injuries may be from acute or chronic traumatic episodes. Cervical spine instability was seen in an amateur high jumper as a result of chronic repetitive flexion loading of her cervical spine due to incorrect landing technique. The instability from these types of flexion injuries is generally unrecognized on a routine lateral radiograph. The presence of slight anterior subluxation, simple compression fractures, or subtle kyphotic angulation at one cervical level should alert the physician to this diagnosis. Flexion extension views are useful to demonstrate this instability. Occupations and sports which involve repetitive flexion stress to the cervical spine are at risk for this type of late instability. Therefore, in high jumping careful attention to safe techniques of landing is of utmost importance.