INJ RYCLINIC

Sports Medicine 13 (3): 214-222. 1992 0112-1642/92/0003-0214/$04.50/0 © Adis International Limited. All rights reserved.

SPOll08

Atraumatic Osteolysis of the Distal Clavicle A Review

Bernard R. Cahill Center for Sports Medicine. Peoria. Illinois. USA

Contents

214 215 216 217 217 219 219 219 219 219 220 221 221

Summary

Summary I. Case Material 2. Clinical Presentation 3. Natural History of Untreated AODC 4. Radiographic Findings 5. 99mTc-Labelled Phosphate Scintigraphy 6. Diagnosis of AODC 7. Association of AODC with Other Shoulder Syndromes

7.1 Impingement Syndrome 7.2 Glenohumeral Instability

8. Aetiology, Stress Failure Syndrome 9. Treatment

10. Conclusion

Atraumatic osteolysis of the distal clavicle (AODC) in athletes is a stress failure syndrome of the distal clavicle. It is related to intolerable exercise doses. For some athletes, the acromioclav­icular joint is the weak link in their musculoskeletal system. There is never a history of a major injury to the acromioclavicular joint. It occurs principally in young athletes who have a long history of training and performance. It is further characterised by athletes who generally have an associated intense strength training programme.

The condition will inexorably progress to decrease the level of performance and later interfere with activities of daily living.

If the athlete is unwilling to alter his or her exercise training and performance regimen, she or he will eventually become surgical candidates. The results of excision of the distal clavicle for AODC are good or excellent in virtually all cases.

The diagnosis of AODC is confirmed by the history of accumulative exercise doses and the key historical feature of intensive participation in strength training. Local tenderness will be found at the acromioclavicular joint. plain radiographs will show degenerative changes in the vast ma­jority of cases and joint scintigraphy must be positive to confirm the diagnosis.

Atraumatic Osteolysis of the Distal Clavicle

Dupas (1936) first described traumatic osteo­lysis of the distal clavicle. Nearly 30 years later, Madsen (1963) summarised the findings in 8 patients of his own and reviewed 8 other cases re­ported in the literature, although he did not review the two patients reported by Stahl (1954). From 1963 to 1982, 20 additional cases were reported, making a total of 38 cases of traumatic osteolysis described in the world literature (Allen 1967; Ja­cobs 1964; Levine et al. 1976; Strauch 1970; Zanca 1971). 34 of these 38 patients had a history of acute trauma to the shoulder or acromioclavicular joint itself.

It was not until 1959 that atraumatic osteolysis of the distal clavicle (AODC) was reported by Eh­richt, when he described the occurrence of osteo­lysis of the distal clavicle in an air hammer oper­ator. This report was followed by a description of osteolysis in a patient who practised judo, a deliv­ery man, and a handball player (Murphy et al. 1975; Seymore 1977; Smart 1972). None of these patients had a history of injury to the shoulder. Lamont (1982) described what may have been AODC. In 1982 I reported 46 cases of atraumatic osteolysis of the distal clavicle, all in men, 45 of whom were weightlifters (Cahill 1982). Scavenius et al. (1987) reported 3 cases of what he termed nontraumatic osteolysis in young male athletes.

The pathological changes secondary to disrup­tion of the acromioclavicular joint are common and usually recognised by the clinician. However, the same sequence of events in a patient without a his­tory of shoulder trauma continues to be a diag­nostic problem for many. The purpose of this pa­per is to describe the clinical, pathological, life history and treatment of atraumatic osteolysis of the distal clavicle in the athlete. A case is made for a stress failure syndrome of the acromioclavicular joint as the aetiology of this condition.

1. (7ase ~aterial

Since 1982, when 46 patients with AODC were reported, 72 other patients have been treated by the author. None of these 118 patients had a sig­nificant history of injury and with the exception of

215

2 patients, all were athletes or exercisers involved in some form of weight-training.

Strength-training exercises as practised by body­builders and competitive weightlifters remain the leading historical feature of AODC, followed by American football, Olympic weightlifting and swimming. The incidence of AODC appears to have increased in parallel with the development during the past 20 years of strength training as an integral part of the training regimen of all sports.

Bilateral symptoms are common, representing nearly 20% of this series, and joint scintigraphy in­dicates a 40% bilateral involvement of the distal clavicle. In this bilateral scintigraphic group, 20% of patients are symptomatic on only one side, but may later become symptomatic on the opposite side.

Throwing athletes are no longer immune to AODC. Seven baseball pitchers and I catcher, 4 tennis players and 2 racquetball players are in­cluded in this post-1982 material. Eleven of these athletes had a significant history of strength train­ing as part of their overall programme.

No cases of AODC in women were reported in my 1982 study. Since then, 10 female athletes, all with strength training as part oftheir programmes, have been treated. The athletes competed in weight events in track and field (4), volleyball (2), bas­ketball (2) and bodybuilding (2).

The average age of patients with AODC re­ported in 1982 was 23.3 years. This presenting age has declined to 21 years in the case material re­ported from 1982 to 1990 and is presumed to be a result of the cumulative stresses on the acrom­ioclavicular joint generated by the earlier entry of the athlete into sports, the addition of strength training programmes, and the intensity of the training programmes, that is, the cumulative effect of an increased and prolonged exercise dose.

The dominant extremity has a slightly higher incidence of symptomatic AODC than the non­dominant extremity. There is a higher correlation than dominance that is related to the architecture of the sternoclavicular joint as described by De­Palma (1983). The highest incidence is in type III followed by type II acromioclavicular joint (fig. I).

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Sports Medicine J3 (3) 1992

Fig. 1. (A) A 19-year-old college wrestler with a I-year history of pain in the right shoulder. His radiographic changes are loss of the subchondral line and cystic changes of the lateral clavicle in this type II acromioclavicular joint. loint scintigraphy was positive for atraumatic osteolysis of the distal clavicle. He declined activity modification. (D,C) Three years later he has bilateral symptoms. disabling on the right . (D) The right anteroposterior view shows cystic changes and osteoporosis of the lateral clavicle. (C) The right A-C view shows hypertrophic changes and remodelling of the subchondral region . (D) Parallel hole joint scintigraphy indicates bilateral involvement of both the lateral clavicle and the acromion. more intense on the right. He underwent bilateral excision of the lateral clavicle and has returned to wrestling.

2. Clinical Presentation

Symptoms begin insidiously with a slow onset of pain in the area of the acromioclavicular joint usually after a vigorous work-out or strength train­ing session. The painful symptom is usually de­scribed as a dull ache and the patient will often state that when they palpate the acromioclavicular joint it is swollen and slightly tender. There may be some radiation to the adjacent deltoid muscle or the superior border of the trapezius, but this is an unusual early historical feature (fig. 2).

As AODC progresses the athlete begins to de­scribe the onset of pain at the beginning of exercise

worsening with the performance and lasting some­times several days after the exercise bout. At this stage, performance is nearly always interfered with. When strength-training is a significant aspect of the training programme, the athlete characteristically describes the pain at the acromioclavicular joint while doing bench-presses, dips or push-ups. The throwing athlete will usually describe the pain as occurring and/or being more intense at the top of the ball release position.

When uncomplicated by other conditions, the range of motion of the glenohumeral joint is nor­mal and muscle atrophy has not been noted.

Mild prominence over the acromioclavicular

Atraumatic Osteolysis of the Distal Clavicle

joint is relatively common in unilateral cases, how­ever, in bilateral cases it may be difficult to eval­uate. Tenderness is always present at the acrom­ioclavicular joint in AODC. Instability of the joint is not a feature, but crepitation with range of mo­tion of the glenohumeral joint may be. At times frank tenderness over the acromioclavicular joint may not be found, but anterior posterior mani­pulation of the clavicle will cause pain to be re­ferred to the acromioclavicular joint.

Using the aillicted extremity to grasp the op­posite shoulder and pull will in a high percentage of cases cause pain to be referred to the involved acromioclavicular joint, as will requesting the patient to do push-ups.

As AODC progresses, all throwing motions and performance in general become painful and even­tually activities of daily living will be deleteriously affected.

3. Natural History of Untreated AODC

Patients with AODC in the early stages can fre­quently be treated conservatively by modifying their training regimens. Usually this may mean a de­crease in their exercise activities and eliminating symptom provocative strength training man­oeuvres such as bench presses, push-ups and other intensive strength training techniques for the upper extremity. This may be accomplished by mani­pulating the exercise prescription and having the athlete perform high repetition, low resistance ex­ercises. In the throwing athlete a slight change in the throwing motion may be all that is necessary to alter the course of AODC. Steroid injections into the joint are ineffective, giving only short term re­lief and will not alter the inexorable course of AODC if the athlete is unwilling to modify his training regimen. Normally, if the athlete contin­ues, in spite of pain, to train and perform at the current level of intensity, the symptoms will worsen, performance will drop and in cases where the pres­entation was unilateral, the contralateral shoulder will eventually become involved (fig. 3).

For most amateur athletes who will accept al­ternative forms of exercise and altered exercise

217

doses, the progression of AODC can be stopped. However, even several years lay-off does not seem to cure or eliminate the predisposition towards AODC, and if these athletes return to their original exercise programme within 6 months to a year, symptoms will resume.

4. Radiographic Findings

The most comprehensive radiographic study of the acromioclavicular joint was made by Zanca (1971) who pointed out the quotidian occurrence of asymptomatic degeneration of that joint. His

Shoulder pain

Symptoms localised only toAC joint

1 Tenderness at AC joint

1 x-Ray changes to distal

clavicle

1 Positive bone scan

1 Autraumatic osteolysis

+ ...

I

Modify activities

Resect distal clavicle

Symptoms and signs of impingement,

subluxation, etc.

1 Symptoms and signs

of AODC

1 x·Ray changes to distal

clavicle

1 Positive bone scan

for AOCD

1 If a surgical candidate,consider; resect distal clavicle; along with primary procedure

Fig. 2. Atraumatic osteolysis of the distal clavicle (AODC).

218 Sports Medicine 13 (3) 1992

Fig. 3. An l8-year-old college football tackler who has never had a shoulder injury. but has been in intensive strength training for the past 4 years. Has had pain at the right acromioclavicular region for 8 months and is no longer able to perform or train . (A) Presenting radiographs show cystic changes of the right lateral clavicle in this type 1Il acromioclavicular joint. (R,C) Pin hole joint scintigraphy shows intense activity of the right lateral clavicle. The left asymptomatic shoulder shows increased uptake, but of a smaller degree. Neither the right or left acromion is involved. (D) He underwent resection of his right lateral clavicle and resumed his training 8 weeks later. Five months after surgery he began and played the entire season for a division I football team. During the season his left shoulder became symptomatic. The acromioclavicular view of the left type 1Il acromioclavicular joint shows loss of the subchondral line and microcystic subchondral changes. His scan was markedly positive for atraumatic osteolysis of the distal clavicle.

data has never been compared to the scintigraphic level of activity of the acromioclavicular joint in active men. It is believed, however, that scinti­graphic activity, indicates either increased blood flow or osteoblastic activity, either of which are pathological changes.

The radiographic finding in traumatic autolysis of the distal clavicle, described by Madsen (1963) and Levine et at. (1976), as tapering of the distal part of the clavicle, is not seen in AODC. Murphy et at. (1975) and Jacobs (1964) stated that the ear­liest radiographic changes of osteolysis after trauma may ensue in 4 weeks. In my experience with

AODC, radiographic changes as recorded by stand­ard x-ray techniques are subtle and late manifes­tations of the application of the exercise dose.

The radiographic changes characteristic of AODC are the loss of subchondral bone detail at the distal end of the clavicle and microcystic ap­pearances in the subchondral area. Osteoporosis of the lateral third of the clavicle may rarely occur.

To evaluate the acromioclavicular joint ade­quately, the 13° cephalad technique (fig. I) as well as joint scintigraphy must be performed. Neither nuclear magnetic resonance nor computed tom-

Atraumatic Osteolysis of the Distal Clavicle

ography have been helpful in the confirmation of the diagnosis of AODC

5. 99mTc-Labelled Phosphate Scintigraphy

Joint scintigraphy is essential to confirm the diagnosis of AODC Joint scintigraphy demon­strating increased uptake of the radiotracer was positive in 1 or both shoulders in all 118 patients in this series. 48 cases had bilateral involvement, but the asymptomatic side had a lower stage of scintigraphic activity than the affected side.

Approximately 30% of the patients with AODC will have increased scintigraphic activity of the ad­jacent acromion.

The sensitivity of joint scintigraphy in detecting pathology in patients with radiographically normal joints is well known. In 17% of the patients with asymptomatic, radiographically normal shoulders, joint scintigraphy was positive. Symptomatic shoulders with questionably normal x-rays were scintigraphically positive in over 90% of the patients. The patients with normal joint scinti­graphy were excluded from this study since we be­lieve that a positive technetium scan is the sine qua non of the diagnosis of AODC

6. Diagnosis of AODC

The diagnosis of AODC must be considered in any athlete or exerciser with pain in the epaulet area (point of the shoulder) who also has a history of strength training. The differential diagnosis must consider cervical, glenohumeral, coracoacromial arch and other sources of shoulder pain. The diag­nosis is probable if there is a history of epaulet pain later localising at the acromioclavicular joint as­sociated with local tenderness at this joint. Ra­diography as previously described will be positive for AODC in the vast majority of cases. The final diagnosis is confirmed only by positive joint scin­tigraphy of the acromioclavicular joint.

7. Association of AODC with Other Shoulder Syndromes

In the shoulder, as with stress failure syndromes elsewhere in the musculoskeletal system, several anatomical areas may become simultaneously or

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sequentially symptomatic. There be a cause and ef­fect as in foot dysfunction contributing to patellar stress and the anterior knee pain syndrome. Al­ternatively, the stress failure syndrome may be a simultaneous development, as when multiple stress fractures are present in the lower extremity of a runner.

In the shoulder, AODC frequently accompanies the impingement syndrome and glenohumeral in­stability. It is usually a contributor to symptoms in the impingement syndrome and a distinct entity when associated with glenohumeral instability.

7.1 Impingement Syndrome

Neer and colleagues (Neer 1983; Neer et al. 1983) have pointed out the frequent contribution that the acromioclavicular joint makes to the overall path­ology of the impingement syndrome. They further emphasised the importance of resection of the dis­tal clavicle in order to decompress the coraco­acromial arch adequately in some patients with the impingement syndrome (Neer 1983). Neer consid­ers the acromioclavicular joint to be an integral part of the coracoacromial arch.

The association of AODC with the impinge­ment syndrome in athletes is probable if there is localised tenderness at the acromioclavicular joint and this may be confirmed by joint scintigraphy. Joint scintigraphy will not be positive in uncom­plicated athletic impingement syndromes.

In a separate series of my athletic patients with impingement syndrome, the incidence of AODC as demonstrated by positive acromioclavicular joint scintigraphy was as high as 10%.

In athletic patients with the impingement syn­drome who have tenderness at the acromioclavi­cular joint and abnormal radiographs of this joint should undergo a scintigraphic evaluation and ex­cision of the distal clavicle as a potential adjunc­tive procedure to standard coracoacromial arch de­compression.

7.2 Glenohumeral Instability

In any athlete with glenohumeral instability, a careful search for shoulder pain during periods of glenohumeral stability is essential. If there is shoul-

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Stress Restl recovery •

AhatiS~he critical

balance?

Adverse response Catabolic Atrophic

Desired response Training

Conditioning

Fig. 4. A schematic representation of Selye's General Ad­aptation Syndrome. The appropriate cyclic application of stress associated with adequate rest or relief from stress will provide desirable biological adaptations (training and con­ditioning). An error in the correct balance between stress and rest will result in detrimental adaptations (atrophy or tissue destruction).

der pain during periods of stability, the clinician should be alerted to an additional pathological pro­cess. An additional tocsin of combined pathology is acromioclavicular joint tenderness in the athlete with shoulder instability. If there is a history of pain localised to the acromioclavicular joint and tenderness there, especially during periods of gle­nohumeral stability, joint scintigraphy should be performed and can confirm the association of AODC . In such patients resection of the distal cla­vicle should be considered when reconstructing the glenohumeral joint. Like the athletic impingement syndrome, the incidence of AODC in glenohu­meral instability has been nearly 10%.

There has been no alteration in the rehabilita­tive pattern or results in 10 of my patients with glenohumeral instability and AODC, 6 were dis­locaters, 4 were subluxers, who underwent com­bined reconstruction of the glenohumeral joint and resection of the distal clavicle.

8. Aetiology, Stress Failure Syndrome

The accumulative stress applied to the shoulder joint over an ever-lengthening athletic career and the additional stresses of strength-training produce an exercise dose that must eventually become physiologically intolerable to some particular sus-

Sports Medicine 13 (3) 1992

ceptible weak link in the musculoskeletal system. This physiological intolerance to accumulative stress is a stress failure syndrome now poorly termed an 'overuse syndrome'.

Selye's (1950) General Adaptation Syndrome proposes that biological adaptations are the result of stresses and how they are applied to biological systems (fig. 4). These biological adaptations may be beneficial or detrimental to the organism. The stresses we are most concerned with are of two gen­eral types, the psychological and the physiological. As sport medicine practitioners, we are generally more concerned with the physiological stresses as represented by the exercise dose to the entire organism, or in this case, the acromioclavicular joint.

At some exercise dose level every organism will experience a detrimental biological adaptation or stress failure syndrome (fig 5). The elusive exercise dose that is the quest of all clinicians is the max­imal tolerable training dose and to keep this dose below the catabolic exercise dose which will pro­vide detrimental biological adaptations.

Pathological material from 12 patients under­going resection of the distal clavicle was examined microscopically. This material was characterised as representing typical degenerative joint disease. However, there were frequent areas of subchondral microfracture with abundant evidence of healing

Time

Fig. 5. There are 4 exercise doses. From the lowest to the highest they are atrophic. conditioning. training and cata­bolic. From any level of conditioning or training exercise dose, a lower dose will become relatively atrophic. Note that the catabolic exercise dose begins long before symptoms occur. Joint scintigraphy documents this in atraumatic osteolysis of the distal clavicle (fIg. 3).

Atraumatic Osteolysis of the Distal Clavicle

process by new bone formation. Lamont (1982) re­ported osteolysis of the distal clavicle and de­scribed cystic and erosive changes of the distal cla­vicle, but not fractures.

The increased scintigraphic activity seen in patients with AODC was due to increased osteo­blastic activity and not to an increased regional blood flow.

We believe the scintigraphic and histological evidence support the evidence that AODC is a stress fracture of subchondral bone resulting from accumulative exercise dose over months or years.

9. Treatment

Conservative treatment of AODC should be di­rected toward eliminating the most symptom pro­vocative aspect of the training programme. This is usually discovered to be strength-training routines. It is most beneficial to alter the training by elim­inating or altering provocative strength training ex­ercises by decreasing their intensity. Nonsteroidal anti-inflammatory drugs or intra-articular injec­tions are temporising and pernicious methods of therapy. They should never be employed in the young athlete.

AODC inexorably progresses if the stresses are not redu~d or altered. Since my 1982 report on AODC, it has been increasingly difficult to counsel the athlete to accept a lower level of stress to the shoulder. The reasons are both philosophical and socioeconomic and are a separate topic. As a re­sult, fewer athletes or exercisers are willing to ac­cept conservative recommendations.

The indications for surgical management of AODC are unchanged from my 1982 report and are: (a) a confirmed diagnosis of AODC, and (b) an unwillingness on the part of the athlete to accept a lower exercise dose or level of performance.

The surgical treatment is resection of the distal clavicle. Gurd (1941) and Mumford (1941) de­scribed this technique simultaneously, but both ad­mit they were not the first to discover this proce­dure. Poor results of this procedure as reported are usually due to the pathological process that neces­sitated the excision or perhaps a mistaken diag-

221

nosis. This procedure has been widely criticised (Cook & Tibone 1988; Rockwood & Green 1984).

Cook & Tibone (1988) reported no loss of strength in patients with grade I or II dislocations of the acromioclavicular joint, and Wirth and Breitner (1984) recommend resection of the lateral end of the clavicle for AODC.

Although we have not reported our surgical re­sults for resection of the distal clavicle in AODC, we have not detected a decrease of strength com­pared to the opposite shoulder; in fact; the opposite occurred, especially in competitive weightlifters.

Since 1982, 40 of 72 AODC patients have undergone resection of their distal clavicle. The re­sults have been good or excellent in 37 patients. None of the surgical patients discontinued their sport. The 3 patients with poor results were not able to improve their performance after their sur­gical procedure, but their strength was equal to the opposite shoulder. The good or excellent patients who continued their sport all improved their pre­vious performance record and this was especially documented in the powerlifters and the Olympic weightlifters.

The results of surgical treatment are so reassur­ing that I do not hesitate to recommend this pro­cedure to well motivated mature patients.

10. Conclusion

Atraumatic osteolysis of the distal clavicle is a clinical entity seen principally in athletes, espe­cially those who integrate strength-training to their sport programmes. As the importance of strength training for sports performance increases and an ever earlier entrance of children into sport contin­ues so will the incidence of AODC increase. Re­search to ameliorate the effects of this entity is vi­tal. Principal areas of research are epidemiological and biomechanical. Epidemiological longitudinal and cross-sectional studies are necessary to estab­lish the incidence and plan interventional experi­ments. Biomechanical analysis of the acromioclav­icular joint, especially during the bench press, are urgently needed to determine alternate methods,

222

equally efficient, that are less stressful to the AC joint.

References

Allen We. Post-traumatic osteolysis of the distal clavicle. Post­graduate Medicine 41: A73-A77, 1967

Cahill BR. Osteolysis of the distal part of the clavicle in male athletes. Journal of Bone and Joint Surgery 64A: 1053-1058, 1982

Cook F, Tibone J. The Mumford procedure in athletes: an ob­jective analysis of function. American Journal of Sports Med­icine 16: 97-100, 1988

DePalma A. Surgery of the shoulder, 3rd ed., pp. 39, J.B. Lip­pincott, Philadelphia, 1983

Dupas J, Badelon P, Dayde G. Aspects radiologiques d'une os­teolyse essentielle progressive de la main gauche. Journal of Radiology 20: 383-387, 1936

Ehricht HG. Die Osteolyse im lateralen Claviculaende nach Pres­luftschaden. Archiv fiir Orthopadische und Unfall-Chirurgie 50: 576-582, 1959

Gurd F. The treatment of complete dislocation of the outer end of the clavicle: an hitherto undescribed operation. Annuals of Surgery; 113: 1094-1098, 1941

Jacobs P. Post-traumatic osteolysis of the outer end of the cla­vicle. Journal of Bone and Joint Surgery 46B: 705-707, 1964

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Madsen B. Osteolysis of the acromial end of the clavicle following trauma. British Journal of Radiology 36: 822-828, 1963

Mumford E. Acromioclavicular dislocation. Journal of Bone and Joint Surgery 23: 799-802, 1941

Sports Medicine 13 (3) 1992

Murphy OB, Bellamy R, Wheeler W, Brower TD. Post-traumatic osteolysis of the distal clavicle. Clinical Orthopaedics 109: 109-114, 1975

Neer CS. Impingement lesions. Clinical Orthopaedics 173: 70, 1983

Neer CS, Craign E, Fukuda H. Cuff tear arthrQpathy. Journal of Bone and Joint Surgery; 65A: 1232, 1983

Rockwood C, Green D. Fractures in adults, 2nd ed., JB Lippin­cott, Philadelphia, 1984

Scavenius M, Iversen B, Sturup J. Resection of the lateral end of the clavicle following osteolysis, with emphasis on nontrau­matic osteolysis of the acromial end of the clavicle in athletes. Injury 18: 261-263, 1987

Selye H. The physiology and pathology of exposure to stress, ACT A, Inc., Montreal, Canada, 1950.

Seymore EQ. Osteolysis of the clavicular tip associated with re­peated minor trauma to the shoulder. Radiology 123: 56, 1977

Smart MJ. Traumatic osteolysis of the distal ends of the clavicles. Journal of the Canadian Association of Radiologists 23: 264-266, 1972

Stahl F. Considerations on post-traumatic absorption of the outer end of the clavicle. Acta Orthopaedica Scandinavica 23: 9-13, 1954

Strauch W. Posttraumatische Osteolysen des lateralen Klaviku­laendes. Radiologia Diagnostica II: 221-229, 1970

Wirth C, Breitner S. Die Resektion des Akromialen Klaviku­laendes bei der Schultereckgelenksarthrose. Zeitschrift fur Or­thopadie und ihre Grenzgebiete 122: 208, 1984

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Correspondence and reprints: Dr Bernard R. Cahill. 303 N. Kumpf Blvd, Peoria, IL 61605, USA.