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Effect of elbow position on grip and key pinch strength
Effect of elbow position on grip and key pinch strength Twenty-nine college women participated in a study to investigate the effect of elbow position on grip and key pinch strength evaluations. Standardized instructions and positioning were followed with the exception of the two elbow positions. The elbow was flexed to 900 in one test condition and it was fully extended in the other. The results showed a significantly stronger grip strength measurement in the 900 elbow flexed position than in the fully extended position. For evaluation of key pinch strength, both hands were stronger in the elbow flexed position, but only the right hand was significantly stronger. This study supports the use of the elbow flexed position in standardized grip and key pinch evaluations. (J HAND SURG 10A:694-7, 1985.)
Virgil Mathiowetz , M.S. , Cheryl RenneIIs, B.S ., and Lori Donahoe , B.S. , Milwaukee, Wis.
Various studies have shown that wrist position " 2 and body positiorr' affect hand strength scores. There are no reports on whether elbow position is also a variable. In some previous studies, elbow position has been standardized in extension' or 90° of flexion, 1.4 while other studies did not control elbow position. 5.6 The question remains : Does elbow position affect hand strength scores? Pryce 1 examined the effect of wrist position on grip strength. He tested 30 right-handed adults with normal right upper extremities. The elbow was positioned at 90° of flexion for all the tests . Wrist positions were controlled by splints for each of the nine test positions. The sequence of test positions was randomly assigned . Results showed no significant differences in grip strength with test positions of neutral and 15° extension and neutral and 15° ulnar deviation or any combination of these positions. Significantly lower grip strength scores were recorded when the wrist was positioned in 15°of flexion and/or 30°ulnar deviation . Similar results were reported by Kraft and Detels.? In a study of 20 normal subjects, they found no significant differences when the wrist was positioned in neutral, 15°, or 30° extension, and significantly lower scores occurred when the wrist was positioned in 15° flexion. They also reported a similar trend with pinch strength, although only
From the University of Wisconsin-Milwaukee, Occupational Therapy Program, Milwaukee, Wis. Received for publication Aug. 27, 1984; accepted in revised form Jan. 3, 1985. Reprint requests: Virgil Mathiowetz, MS, University of Wiscons inMilwaukee, Occupational Therapy Program, P.O. Box 413 , Milwaukee , WI 53201.
694
THE JOURNALOF HAND SURGERY
the neutral wrist position was significantly higher than the 15° flexion position. Teraoka' studied the effect of three body positions on grip strength: standing, sitting, and supine. The elbow was fully extended in each test position. He tested 9543 males and females ranging from 15 to 55 years of age. Results showed that grip strength was stronger in the standing position than in the sitting position for all age-groups and in both sexes . Likewise, grip strength was stronger in a sitting position than in a supine position. Mathiowetz et al." recently used standardized positioning to evaluate the reliability and validity of four tests of hand strength: grip, tip pinch , key pinch, and palmar pinch. The 27 subjects were seated with their shoulder adducted and neutrally rotated, elbow flexed at 90°, forearm in the neutral position , and the wrist between 0° and 30° extension and between 0° and 15° of ulnar deviation . The highest test-retest reliability (I' = 0.81 or better) was reported when the mean of three trials was used . Very high inter-rater reliability (I' = 0.98 or above) was reported for each test. The purpose of this study was to evaluate if elbow position affects grip and key pinch strength scores, and if so, what position has the higher strength scores . It was hypothesized that there would be no significant difference in grip and key pinch strength scores when the elbow was positioned in 90° of flexion or fully extended. Methodology Subjects. A sample of 29 female occupational therapy students ranging from 20 to 34 years of age volunteered for the testing. Screening criteria for subjects
Vol lOA, No.5 September 1985
Effect of elbow position on grip
695
Fig. 2. Key pinch is thumb pad to the lateral aspect of the middle phalanx of the index finger.
position was tested first. Three successive grip measurements were taken on each hand with the elbow flexed to 90° and fully extended. The same procedures were also followed for key pinch measurements. The standard adjustable handle dynamometer was set at the second handle position for all subjects. The dynamometer was lightly held around the readout dial by the examiner to prevent inadvertent dropping. The pinch gauge was held by the examiner at the distal end to prevent inadvertent dropping."
Instructions" Fig. 1. The standardized positioning used for grip strength measurement with the elbow flexed at 90°.
included no previous history of neuromuscular or orthopedic dysfunction that would significantly affect hand strength. Instruments. A Jamar dynamometer* was used to test grip strength, and a pinch gauget was used to test lateral pinch strength. The calibration accuracy of each instrument has been previously reported." Procedure. Subject's name, age, sex, hand dominance, and health status were recorded. Hand dominance was determined by asking" Are you right -handed or left-handed?" The dominant hand was tested first. Subjects were tested in a classroom setting while seated comfortably on a standard height chair (46 em) without arm rests." To control for the effect of fatigue, test positions were alternated for each subject. For odd numbered subjects, the elbow flexed position was tested first. For even numbered subjects, the elbow extended *Jamar Dynamometer, Asimow Engineering Co., Los Angeles, CA 90024. tPinch Gauge, B & L Engineering, Santa Fe Springs, CA 90670.
1. Grip strength. (Fig. 1) "I want you to hold the handle like this and squeeze as hard as you can." The examiner demonstrates and then gives the dynamometer to the subject. After the subject is positioned appropriately, the examiner says, "Are you ready? Squeeze as hard as you can." As the subject begins to squeeze, say, "Harder! ... Harder! ... Relax." After the first trial score is recorded, the test is repeated with the same instructions for the second and third trial and for the other hand. Both the flexed and extended positions received the same instructions. 2. Key (lateral) pinch. (Fig. 2) "I want you to place your thumb on top and your index finger below as I'm doing and pinch as hard as you can." The examiner demonstrates the position and gives the pinch gauge to the subject. After the subject is appropriately positioned, the examiner says, "Are you ready? Pinch as hard as you can." As the subject begins to pinch, say, "Harder! . . . Harder! . . . Relax." After the first trial score is recorded, the test is repeated with the same instructions for the second and third trials and for the other hand. Both the flexed and extended positions received the same instructions. Data analysis. A two-tailed, paired data t test was used to analyze whether there was a significant differ-
696
The Journal of HAND SURGERY
Mathiowetz, Rennells, and Donahoe
Table I. Comparison of grip and lateral pinch strength of 29 college women when the elbow is flexed at 90° or fully extended Test Grip
Hand
R L
Key pinch
R L
Elbow position
M
SD
SE
T value
Flexion Extension Flexion Extension Flexion Extension Flexion Extension
69.2 66.7 61.3 57.3 17.0 16.5 15.9 15.5
9.4 9.8 10.4 11.2 2.7 2.4 2.5 2.2
I.7 1.8 1.9 2.1 0.50 0.44 0.47 0.40
2.59* 3.3 It 2.02* 1.08
*p < 0.05. tP < 0.01.
ence between the elbow flexed position and the elbow extended position for grip and key pinch strength scores. Results
Data revealed that grip strength scores were significantly higher when the elbow was in a 90° flexed position than in the fully extended position (Table I). For key pinch, there were significantly higher scores for the 90° flexed position in the right hand; however, left hand scores did not reach the 0.05 level of significance. Discussion
The hypothesis that elbow position would not significantly affect grip strength scores was not supported by this study. Grip strength scores were significantly higher when the elbow was positioned at 90° flexion than when the elbow was fully extended. For key pinch, the null hypothesis was supported in the left hand, but not in the right hand. However, there was a trend of higher scores for the elbow flexed position even in the left hand. Elbow position clearly affects grip and key pinch scores in the right hand and may also affect key pinch scores in the left hand. The results of this study support the recommendations of the American Society of Hand Therapists' that arm positioning should be standardized for hand strength testing. Specifically, the findings support their recommendation that the 90° flexed elbow position should be used in testing. These results also support the standardized positioning used by Mathiowetz et al. 8 to collect new adult norms for four tests of hand strength; grip, tip pinch, key pinch, and palmar pinch. Hand strength norms collected in a 1971 study" should be questioned because elbow position was not controlled during data collection.
Many questions remain regarding the effect of elbow position on hand strength. Future research should use a larger and more diverse sample. For example, would similar results be found in a study of male subjects or subjects older than 35 years of age? Does elbow position also affect tip and palmar pinch strength scores? Would other elbow positions such as 110° or 70° flexion cause even higher hand strength scores? On a more theoretic basis, why is hand strength stronger when the elbow is flexed at 90° versus the fully extended position? Considering the evidence for specificity of training," one could speculate that the average person does more tight gripping with the elbow flexed than extended. Consequently, they would be stronger in that position. However, this question needs further study. The authors thank Frank Stein, Ph. D., for research and statistical consultation, Mary Dowe for assistance in data analysis, and the University of Wisconsin-Milwaukee occupational therapy students whose participation made this research possible.
REFERENCES I. Pryce JC: The wrist position between neutral and ulnar deviation that facilitates the maximum power grip strength. J Biomech 13:505-11, 1980 2. Kraft GH, Detels PE: Position of function of the wrist. Arch Phys Med Rehabil 53:272-5, 1972 3. Teraoka T: Studies on the peculiarity of grip strength in relation to body positions and aging. Kobe J Med Sci 25:In, 1979 4. Mathiowetz V, Weber K, Volland G, Kashman N: Reliability and validity of hand strength evaluations. J HAND SURG 9A:222-6, 1984 5. Kellor M, Frost J, Silberberg N, Iversen I, Cummings R: Hand strength and dexterity; norms for clinical use. Am J Occup Ther 25:77-83, 1971 6. Bowman OJ, Katz B: Hand strength and prone extension
Vol lOA, No.5 September 1985
in right-dominant , 6 to 9 years old. Am J Occup Ther 38:367-76, 1984 7 . Fess EE, Moran CA : Clinical assessment recommendations. 1981, American Society of Hand Therapists 8. Mathiowetz Y, Kashman N , Volland G , Weber K, Dowe
Effect of elbow position on grip
M, Rogers S: Grip and pinch strength: normative data for adults . Arch Phys Med Rehabil 66:69-72 , 1985 9 . Stallings LM: Motor learning: from theory to practice. St. Louis, 1982, The CV Mosby Co, pp 168-9
Dorsal wrist pain and the occult scapholunate ganglion Ten consecutive patients who presented with dorsal wrist pain, no history of trauma, and no physical signs other than local tenderness over the scapholunate ligament junction had surgery. The obvious pathologic finding in eight was ganglionic degeneration in a particular area on the dorsal scapholunate interosseous ligament. The operation resulted in dramatic relief of pain and return to full function for the duration of follow-up in most patients. (J HAND SURG 10A:697703,1985.)
Stephen Flack Gunther, M.D., Washington, D.C.
There are many causes of wrist pain , and this subject has received considerable attention in the orthopedic and hand surgery literature during the past decade. Repeated examinations and radiographs over time usually elicit the cause when the problem is disruption of the intercarpal ligaments, avascular necrosis of a carpal bone, arthritis, tumor, or even chronic infection. Yet, there are occasional patients who remain diagnostic enigmas in that they have chronic dorsal wrist pain without a known injury and without radiographic or physical findings other than tenderness . I present a series of such patients whom I have treated since discovering the existence of ganglionic degeneration in the dorsal scapholunate ligament complex: occult scapholunate ganglion (OSLG) . This discovery was fortuitous and is described in the first case report.
From the Department of Orthopaedic Surgery, Washington Hospital Center, Washington, D.C. Presented in part at the annual meeting of the Eastern Orthopaedic Association, October 1979. Received for publication July 16, 1984; accepted in revisedform Jan. 31, 1985. Reprint requests: Stephen Flack Gunther, M.D., Chairman, Department of Orthopaedic Surgery, Washington Hospital Center, 106 Irving St., N.W., Suite 213, Washington, DC 20010.
Material and methods
Ten consecutive patients were operated over a 7year period from 1977 through 1983. There were seven men and three women. Their ages ranged from 17 to 43 years , and only two were older than the age of 30. They each described a nagging pain of varying intensity in the dorsum of the wrist. They especially had symptoms during periods of heavy activity such as work , sports, or the playing of a musical instrument. The pain had been present without interruption for periods ranging from 5 months to 5 years, the average being slightly more than 2 years . The problem was usually in the dominant wrist, and no patient could remember sustaining an injury. They were unable to play certain sports or practice a musical instrument intensively without developing pain that would persist for at least a day afterward. During periods of rest, the patients were still aware that the wrist was different than the opposite side even though it was not acutely painful. Some were treated with splinting, cortisone injections , and antiinflammatory drugs , but in no case did this alter the eventual course of the disease . Wrist motion was either normal or very slightly restricted by pain at the extremes of either flexion or extension. None of these patients gave a past history of any bump or ganglion on the dorsum of the wrist, and nothing was palpable at the time of examination.
THE JOURNAL OF HAND SURGERY
697
Virgil Mathiowetz , M.S. , Cheryl RenneIIs, B.S ., and Lori Donahoe , B.S. , Milwaukee, Wis.
Various studies have shown that wrist position " 2 and body positiorr' affect hand strength scores. There are no reports on whether elbow position is also a variable. In some previous studies, elbow position has been standardized in extension' or 90° of flexion, 1.4 while other studies did not control elbow position. 5.6 The question remains : Does elbow position affect hand strength scores? Pryce 1 examined the effect of wrist position on grip strength. He tested 30 right-handed adults with normal right upper extremities. The elbow was positioned at 90° of flexion for all the tests . Wrist positions were controlled by splints for each of the nine test positions. The sequence of test positions was randomly assigned . Results showed no significant differences in grip strength with test positions of neutral and 15° extension and neutral and 15° ulnar deviation or any combination of these positions. Significantly lower grip strength scores were recorded when the wrist was positioned in 15°of flexion and/or 30°ulnar deviation . Similar results were reported by Kraft and Detels.? In a study of 20 normal subjects, they found no significant differences when the wrist was positioned in neutral, 15°, or 30° extension, and significantly lower scores occurred when the wrist was positioned in 15° flexion. They also reported a similar trend with pinch strength, although only
From the University of Wisconsin-Milwaukee, Occupational Therapy Program, Milwaukee, Wis. Received for publication Aug. 27, 1984; accepted in revised form Jan. 3, 1985. Reprint requests: Virgil Mathiowetz, MS, University of Wiscons inMilwaukee, Occupational Therapy Program, P.O. Box 413 , Milwaukee , WI 53201.
694
THE JOURNALOF HAND SURGERY
the neutral wrist position was significantly higher than the 15° flexion position. Teraoka' studied the effect of three body positions on grip strength: standing, sitting, and supine. The elbow was fully extended in each test position. He tested 9543 males and females ranging from 15 to 55 years of age. Results showed that grip strength was stronger in the standing position than in the sitting position for all age-groups and in both sexes . Likewise, grip strength was stronger in a sitting position than in a supine position. Mathiowetz et al." recently used standardized positioning to evaluate the reliability and validity of four tests of hand strength: grip, tip pinch , key pinch, and palmar pinch. The 27 subjects were seated with their shoulder adducted and neutrally rotated, elbow flexed at 90°, forearm in the neutral position , and the wrist between 0° and 30° extension and between 0° and 15° of ulnar deviation . The highest test-retest reliability (I' = 0.81 or better) was reported when the mean of three trials was used . Very high inter-rater reliability (I' = 0.98 or above) was reported for each test. The purpose of this study was to evaluate if elbow position affects grip and key pinch strength scores, and if so, what position has the higher strength scores . It was hypothesized that there would be no significant difference in grip and key pinch strength scores when the elbow was positioned in 90° of flexion or fully extended. Methodology Subjects. A sample of 29 female occupational therapy students ranging from 20 to 34 years of age volunteered for the testing. Screening criteria for subjects
Vol lOA, No.5 September 1985
Effect of elbow position on grip
695
Fig. 2. Key pinch is thumb pad to the lateral aspect of the middle phalanx of the index finger.
position was tested first. Three successive grip measurements were taken on each hand with the elbow flexed to 90° and fully extended. The same procedures were also followed for key pinch measurements. The standard adjustable handle dynamometer was set at the second handle position for all subjects. The dynamometer was lightly held around the readout dial by the examiner to prevent inadvertent dropping. The pinch gauge was held by the examiner at the distal end to prevent inadvertent dropping."
Instructions" Fig. 1. The standardized positioning used for grip strength measurement with the elbow flexed at 90°.
included no previous history of neuromuscular or orthopedic dysfunction that would significantly affect hand strength. Instruments. A Jamar dynamometer* was used to test grip strength, and a pinch gauget was used to test lateral pinch strength. The calibration accuracy of each instrument has been previously reported." Procedure. Subject's name, age, sex, hand dominance, and health status were recorded. Hand dominance was determined by asking" Are you right -handed or left-handed?" The dominant hand was tested first. Subjects were tested in a classroom setting while seated comfortably on a standard height chair (46 em) without arm rests." To control for the effect of fatigue, test positions were alternated for each subject. For odd numbered subjects, the elbow flexed position was tested first. For even numbered subjects, the elbow extended *Jamar Dynamometer, Asimow Engineering Co., Los Angeles, CA 90024. tPinch Gauge, B & L Engineering, Santa Fe Springs, CA 90670.
1. Grip strength. (Fig. 1) "I want you to hold the handle like this and squeeze as hard as you can." The examiner demonstrates and then gives the dynamometer to the subject. After the subject is positioned appropriately, the examiner says, "Are you ready? Squeeze as hard as you can." As the subject begins to squeeze, say, "Harder! ... Harder! ... Relax." After the first trial score is recorded, the test is repeated with the same instructions for the second and third trial and for the other hand. Both the flexed and extended positions received the same instructions. 2. Key (lateral) pinch. (Fig. 2) "I want you to place your thumb on top and your index finger below as I'm doing and pinch as hard as you can." The examiner demonstrates the position and gives the pinch gauge to the subject. After the subject is appropriately positioned, the examiner says, "Are you ready? Pinch as hard as you can." As the subject begins to pinch, say, "Harder! . . . Harder! . . . Relax." After the first trial score is recorded, the test is repeated with the same instructions for the second and third trials and for the other hand. Both the flexed and extended positions received the same instructions. Data analysis. A two-tailed, paired data t test was used to analyze whether there was a significant differ-
696
The Journal of HAND SURGERY
Mathiowetz, Rennells, and Donahoe
Table I. Comparison of grip and lateral pinch strength of 29 college women when the elbow is flexed at 90° or fully extended Test Grip
Hand
R L
Key pinch
R L
Elbow position
M
SD
SE
T value
Flexion Extension Flexion Extension Flexion Extension Flexion Extension
69.2 66.7 61.3 57.3 17.0 16.5 15.9 15.5
9.4 9.8 10.4 11.2 2.7 2.4 2.5 2.2
I.7 1.8 1.9 2.1 0.50 0.44 0.47 0.40
2.59* 3.3 It 2.02* 1.08
*p < 0.05. tP < 0.01.
ence between the elbow flexed position and the elbow extended position for grip and key pinch strength scores. Results
Data revealed that grip strength scores were significantly higher when the elbow was in a 90° flexed position than in the fully extended position (Table I). For key pinch, there were significantly higher scores for the 90° flexed position in the right hand; however, left hand scores did not reach the 0.05 level of significance. Discussion
The hypothesis that elbow position would not significantly affect grip strength scores was not supported by this study. Grip strength scores were significantly higher when the elbow was positioned at 90° flexion than when the elbow was fully extended. For key pinch, the null hypothesis was supported in the left hand, but not in the right hand. However, there was a trend of higher scores for the elbow flexed position even in the left hand. Elbow position clearly affects grip and key pinch scores in the right hand and may also affect key pinch scores in the left hand. The results of this study support the recommendations of the American Society of Hand Therapists' that arm positioning should be standardized for hand strength testing. Specifically, the findings support their recommendation that the 90° flexed elbow position should be used in testing. These results also support the standardized positioning used by Mathiowetz et al. 8 to collect new adult norms for four tests of hand strength; grip, tip pinch, key pinch, and palmar pinch. Hand strength norms collected in a 1971 study" should be questioned because elbow position was not controlled during data collection.
Many questions remain regarding the effect of elbow position on hand strength. Future research should use a larger and more diverse sample. For example, would similar results be found in a study of male subjects or subjects older than 35 years of age? Does elbow position also affect tip and palmar pinch strength scores? Would other elbow positions such as 110° or 70° flexion cause even higher hand strength scores? On a more theoretic basis, why is hand strength stronger when the elbow is flexed at 90° versus the fully extended position? Considering the evidence for specificity of training," one could speculate that the average person does more tight gripping with the elbow flexed than extended. Consequently, they would be stronger in that position. However, this question needs further study. The authors thank Frank Stein, Ph. D., for research and statistical consultation, Mary Dowe for assistance in data analysis, and the University of Wisconsin-Milwaukee occupational therapy students whose participation made this research possible.
REFERENCES I. Pryce JC: The wrist position between neutral and ulnar deviation that facilitates the maximum power grip strength. J Biomech 13:505-11, 1980 2. Kraft GH, Detels PE: Position of function of the wrist. Arch Phys Med Rehabil 53:272-5, 1972 3. Teraoka T: Studies on the peculiarity of grip strength in relation to body positions and aging. Kobe J Med Sci 25:In, 1979 4. Mathiowetz V, Weber K, Volland G, Kashman N: Reliability and validity of hand strength evaluations. J HAND SURG 9A:222-6, 1984 5. Kellor M, Frost J, Silberberg N, Iversen I, Cummings R: Hand strength and dexterity; norms for clinical use. Am J Occup Ther 25:77-83, 1971 6. Bowman OJ, Katz B: Hand strength and prone extension
Vol lOA, No.5 September 1985
in right-dominant , 6 to 9 years old. Am J Occup Ther 38:367-76, 1984 7 . Fess EE, Moran CA : Clinical assessment recommendations. 1981, American Society of Hand Therapists 8. Mathiowetz Y, Kashman N , Volland G , Weber K, Dowe
Effect of elbow position on grip
M, Rogers S: Grip and pinch strength: normative data for adults . Arch Phys Med Rehabil 66:69-72 , 1985 9 . Stallings LM: Motor learning: from theory to practice. St. Louis, 1982, The CV Mosby Co, pp 168-9
Dorsal wrist pain and the occult scapholunate ganglion Ten consecutive patients who presented with dorsal wrist pain, no history of trauma, and no physical signs other than local tenderness over the scapholunate ligament junction had surgery. The obvious pathologic finding in eight was ganglionic degeneration in a particular area on the dorsal scapholunate interosseous ligament. The operation resulted in dramatic relief of pain and return to full function for the duration of follow-up in most patients. (J HAND SURG 10A:697703,1985.)
Stephen Flack Gunther, M.D., Washington, D.C.
There are many causes of wrist pain , and this subject has received considerable attention in the orthopedic and hand surgery literature during the past decade. Repeated examinations and radiographs over time usually elicit the cause when the problem is disruption of the intercarpal ligaments, avascular necrosis of a carpal bone, arthritis, tumor, or even chronic infection. Yet, there are occasional patients who remain diagnostic enigmas in that they have chronic dorsal wrist pain without a known injury and without radiographic or physical findings other than tenderness . I present a series of such patients whom I have treated since discovering the existence of ganglionic degeneration in the dorsal scapholunate ligament complex: occult scapholunate ganglion (OSLG) . This discovery was fortuitous and is described in the first case report.
From the Department of Orthopaedic Surgery, Washington Hospital Center, Washington, D.C. Presented in part at the annual meeting of the Eastern Orthopaedic Association, October 1979. Received for publication July 16, 1984; accepted in revisedform Jan. 31, 1985. Reprint requests: Stephen Flack Gunther, M.D., Chairman, Department of Orthopaedic Surgery, Washington Hospital Center, 106 Irving St., N.W., Suite 213, Washington, DC 20010.
Material and methods
Ten consecutive patients were operated over a 7year period from 1977 through 1983. There were seven men and three women. Their ages ranged from 17 to 43 years , and only two were older than the age of 30. They each described a nagging pain of varying intensity in the dorsum of the wrist. They especially had symptoms during periods of heavy activity such as work , sports, or the playing of a musical instrument. The pain had been present without interruption for periods ranging from 5 months to 5 years, the average being slightly more than 2 years . The problem was usually in the dominant wrist, and no patient could remember sustaining an injury. They were unable to play certain sports or practice a musical instrument intensively without developing pain that would persist for at least a day afterward. During periods of rest, the patients were still aware that the wrist was different than the opposite side even though it was not acutely painful. Some were treated with splinting, cortisone injections , and antiinflammatory drugs , but in no case did this alter the eventual course of the disease . Wrist motion was either normal or very slightly restricted by pain at the extremes of either flexion or extension. None of these patients gave a past history of any bump or ganglion on the dorsum of the wrist, and nothing was palpable at the time of examination.
THE JOURNAL OF HAND SURGERY
697