WORK A lournal of Prevention, Assessment & Rehabilitation
ELSEVIER
Work 10 (1998) 181-191
Student paper
The relationship of compliance and grip strength return post-carpal tunnel release surgery T.L. Bamowski, S.c. Blessinger, K.J. Britton, K.E. Flanagan, P.A. Mieling* , M.N. Ptacek, P.A. Moyers Graduate Program in Occupational Therapy, University of Indianapolis, Indianapolis, IN, USA Received 25 April 1997; accepted 1 July 1997
Abstract This study examined the relationship of compliance and grip strength return 6 weeks post-carpal tunnel release surgery on a sample of 11 factory workers residing in the midwest. The percent difference between pre-operative and post-operative grip strengths was - 6.00%. An ANOVA ruled out age as a significant factor in grip strength return (F = 1.20, P = 0.351). A two sample t-test for gender differences in return of grip strength proved insignificant as well (t = 1.01, P = 0.351). The low negative correlation between participant self-report of compliance and percent difference of grip strength was - 0.426. Work was reported as the most significant barrier to compliance. Results of this study suggested that 6 weeks of occupational therapy may not be sufficient for recovery to pre-operational grip strength status. Participants with the greatest amount of compliance in combination with returning to work soon after surgery demonstrated the weakest grip strength. This result implied that the exercise program in association with returning to work may have been too strenuous. Return to work and resulting work demands should be taken into consideration when prescribing home exercise programs. These conclusions are to be considered tentative and cannot be generalized because of the small sample size used to generate the data in this study. © 1998 Published by Elsevier Science "Ireland Ltd Keywords: Jamar dynamometer; Compliance; Grip strength
* Corresponding author, Graduate Programs in Occupational Therapy, University of Indianapolis, 1400 East Hanna Avenue, Indianapolis, IN 46227, USA. Tel.: +13177883432; fax: +13177883480.
1051-9815/98/$19.00 1998 Published by Elsevier Science Ireland Ltd. All rights reserved. PH S1051-9815(97)10026-2
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1. Introduction This study examined the return of grip strength and the compliance of participants with treatment following carpal tunnel release surgeI)'. After carpal tunnel surgeI)' is performed, many patients become concerned with the return of their grip strength as insurance policies generally limit payment for therapy sessions. Insurance companies are asking for the implications of the injuI)' in terms of medical costs and disability, for determination of appropriate goals for the treatment program and for expectation regarding return to functional performance (Jarjour et aI., 1997). Studies need to establish a post-operative time line that provides therapists and third-party payers with a guide to grip strength recoveI)'. An understanding of the return of grip strength will assist employers in gauging when employees may return to work and determining job modifications needed to accommodate any weaknesses in grip (Nancollas et aI., 1995). This study analyzed the effects of age, gender, occupation and return to work on grip strength recoveI)' following carpal tunnel release surgeI)'. Additionally, the relationship between grip strength recoveI)' and compliance with home exercise programs was studied. 1.1. Review of the literature
Cumulative trauma disorder (Cm) is often described as being related to occupational factors that regularly develop over time as a result of repetitive work actions. Carpal tunnel syndrome is the most commonly described and diagnosed condition of cm (Melhorn, 1994). Carpal Tunnel Syndrome (CTS) is a nerve entrapment syndrome in the upper limb, which occurs in 0.1 % of the population and 1-5% of workers in certain occupations (Levine et aI., 1993). The pathophysiology of CTS involves the compression of the median nerve in the palmer aspect of the wrist between the flexor tendons of the forearm muscles and the transverse superficial carpal ligament (Melhorn, 1994). The persistent swelling of the flexor tendons decreases the vascular supply to the median nerve. The compromised vasculature decreases the oxygen and nutrient supply to the
median nerve; therefore the nerve slowly loses the ability to transmit nerve impulses. As a result, scars and fibrous tissue develop within the nerve sheath. Depending upon the stage of injuI)', alterations to the nerve and muscles may be permanent (Melhorn, 1994). There have been reports of reduction in grip strength following carpal tunnel release surgeI)' (Gartsman et aI., 1986; Leach et al., 1993; Melhorn, 1994). Grip strength may be affected in several ways after carpal tunnel decompression. The discomfort of the surgical scar reduces the strength of the hand as well as creating muscle weakness due to several weeks of disuse (Leach et aI., 1993). A direct relationship has also been found between widening of the transverse carpal arch and loss of grip strength (Gartsman et aI., 1986). The study by Gartsman et al. revealed an average decrease of 12% in grip strength with widening of the carpal arch. Strength loss can also be explained by 'bow-stringing' of the flexor tendons caused as the result of the division of the transverse carpal ligament. Bow-stringing diminishes grip strength by altering the lever arm (Gartsman et aI., 1986). Atrophy of the thenar and hypothenar muscles after carpal tunnel release and decreased sensation are other possible causes of the decrease in grip strength (Norkin and Levangie, 1992). A study performed by Fissette et al. (1981) compared grip strength after surgeI)'. The results from their sample showed that participants consistently had stronger grips at 3, 6 and 9 months post-surgery. Rosenbaum and Ochou (1993) criticized the Fissette study by pointing out that there were no pre-operative data to compare the postoperative strength measurements. Studies have found a high correlation between grip strength and age (Mathiowetz et al., 1984; Kellor et aI., 1971; Schmidt and Toews, 1970). Limited research exists addressing age as a significant variable in the return of grip strength following carpal tunnel surgeI)'. Gender has been found to affect the return of grip strength following carpal tunnel decompression (Leach et aI., 1993). Leach et al. found that, in addition to the grip strength of men exceeding the grip strength of women pre-operatively, men
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also have a quicker return rate for grip strength than do women. The grip strength of men returned to the pre-operative level within 12 weeks, while the grip strength of women did not reach the pre-operative level until 26-52 weeks post-operatively (Leach et aI., 1993). Nancollas et ai. (1995) found a correlation between occupationally caused CTS and length of recovery time. If the carpal tunnel syndrome was occupationally caused, a longer recovery time existed. Long-term results following carpal tunnel release, however, were reported to be no different between subjects with occupationally caused carpal tunnel syndrome and non-occupationally caused carpal tunnel syndrome (Nancollas et aI., 1995). Repetitious jobs, according to Nancollas et aI., caused more overuse injuries and reduced the effectiveness of carpal tunnel release. Clearly, occupation does play a role in the incidence of CTS and the length of recovery following carpal tunnel release. Work-related carpal tunnel syndrome represents 47% of all carpal tunnel syndrome cases (Cummings et aI., 1989). In a study conducted by Tountas et ai. (1983), persons with carpal tunnel syndrome with treatment reimbursed by worker's compensation were less likely to have good postoperative results. The average return-to-work time was 12 weeks for subjects with worker's compensation (Tountas et aI., 1983). Subject" who presented with other forms of reimbursement returned to work within 3 weeks (Higgs et aI., 1995). Due to the fact that all of the subjects in this study were receiving worker's compensation, the effect of worker's compensation on the return of grip strength was not examined. This research project examined whether patient compliance would have an effect on the return of grip strength post-carpal tunnel release surgery. Measuring compliance to treatment plans can be a difficult task and has been a topic of debate in the literature. It has been shown, for example, that self-reports of compliance to medication treatment only identified 50% of non-compliant subjects (Haynes et aI., 1976). Other researchers have stated that self-reported follow through of treatment plans is an appropriate measure of compliance (Furth et aI., 1994).
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Questioning the authenticity of the patient's self-report of compliance assumes that the therapist's goals may not be the same as the patient's goals (Furth et aI., 1994). Setting mutual goals needs to be made a priority in order to motivate the patient to be compliant. Compliance is an important issue to consider as payers and practitioners rely on the patient's compliance to the treatment plan in order to ensure successful healing. The research of Waggoner and LeLieuvre (1981) indicated that self-reports coupled with other methods of measurement may be a more accurate way of measuring compliance. More recently, a method of assessment was designed and tested based on self-reported ratings of exercise compliance and therapist-reported ratings of the patient's exercise proficiency (Codori et al., 1992). The hypothesis was that if a positive correlation between the two ratings could be found, the measure of compliance could be considered reliable. Indeed, the researchers did find a positive correlation and commented on the importance of correlating multiple measurements in future research. Codori et al. (1992) also gave some suggestions in soliciting more authentic self-reports from patients. The patients in the study were encouraged to be honest, told to be honest and ensured that their responses would be anonymous. Codori at al. emphasized the importance of the patient feeling safe in revealing the truth. The patients need to be assured, for instance, that reporting a lack of compliance would not be held against him/her in a worker's compensation claim. In order to alleviate any feelings of threat, Codori et al. suggested mentioning to the patient that no one is perfect at complying and that it would be incredulous to expect someone to be 100% compliant. An extensive literature review on compliance in patients with rheumatoid arthritis was conducted by Feinberg (1988). Feinberg found that the most significant factor in patient compliance was the patient-practitioner relationship and that the practitioner's tone of voice and affect influenced the patient's perception of the relationship. If the practitioner presented him/herself with a positive tone, for example, the patient would be more
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likely to comply based on a more positive perception of the relationship. Additional significant factors in patient compliance included the patient's past experience and the patient's understanding of the reasoning behind the treatment prescribed (Feinberg, 1988). Although past research has examined the retum of grip strength following carpal tunnel decompression for patients in Europe (Leach et aI., 1993), little research has been conducted within the US. Gellman et ai. (1989) found grip strength to return to 73% of pre-operative grip strength by 6 weeks post-operatively. It is important that the knowledge base regarding the relationship between compliance and grip strength return following carpal tunnel release surgery be explored. Occupational therapists need to be aware of the factors that influence grip strength return following carpal tunnel release surgery in order to effectively set treatment goals. Insurance and third-party payers also need to understand the factors that influence grip strength return following carpal tunnel release in order to validate their reimbursement policies dictating the payment of limited numbers of occupational therapy treatment sessions. 1.2. Research questions
This study investigated the following questions:
(i) What is the percent difference between pre-
operative grip strength and post-operative grip strength 6 weeks following carpal tunnel release surgery? (ii) Does age affect the return of grip strength? (iii) Does gender affect the return of grip strength? (iv) Does occupation affect the return of grip strength? (v) Does the participant's compliance with the occupational therapy treatment protocol affect the return of grip strength? (vi) Does the amount of time between carpal tunnel release surgery and return to work influence the return of grip strength? 2. Materials and methods 2.1. Subjects
A sample of convenience of 36 persons partici-
pated in this study. Participants were carpal tunnel release surgery patients of an orthopaedic hand surgeon and two occupational therapists practicing in the midwest. The occupational therapists employed by the surgeon collected and provided the data to the researchers. Of the 36 participants, one was excluded due to scores of greater than 15% in the coefficient of variation. A coefficient of variation greater than 15% may demonstrate that the participants failed to give consistent effort during the grip strength trials (Bechtol, 1954). Another 24 participants were excluded as a result of having been tested with a dynamometer which was calibrated after 30 participants with a coefficient of 0.9958. The guidelines of Fess (1987) have established accuracy to 0.9994. A sample size of 11 grip strength participants remained. Other researchers have produced significant post-operative studies with limited sample sizes (Oda and Moritani, 1995; Sotereanos et al., 1997; Srinivasan and Matthews, 1996). The compliance data of the excluded 24 were used in the study. The 35 participants used to study compliance in this study were a minimum age of 18 years, male or female, and residing in the midwest. Participants were diagnosed with carpal tunnel syndrome by EMG tests conducted by a neurologist. Participants excluded from initial participation in this study were those with diagnoses of arthritis and/or diabetes mellitus, or previous surgery for cumulative trauma disorders on the same arm (Al-Qattan et al., 1994; Leach et aI., 1993). If a participant had a bilateral diagnosis of carpal tunnel syndrome, both extremities were treated as separate participants. Of the 11 grip strength participants, six were female and five were male. Nine participants were right-hand dominant and two were left-hand dominant. Five participants had carpal tunnel release surgery performed on the right hand and six had surgery on the left hand. Participants were all employed in factories. Positions varied from managerial work to benchwork and assembly line production, as classified by The Dictionary of Occupational Titles (Department of Labor and Employment and Training Administration, 1991). The mean age of participants was 48.3 years. All par-
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ticipants were receiving workman's compensation benefits.
2.2. Variables The dependent variable in this study was grip strength return, defined as the percent difference between pre-operative grip strength and post-operative grip strength 6 weeks following carpal tunnel release surgery. Independent variables included age, gender, occupation, compliance with treatment protocol and return to work following carpal tunnel release surgery.
2.3. Instruments Grip strength was measured using two standardized adjustable-handle Jamar dynamometers, model number 54251 and 10252232, respectively. As recommended by the American Society of Hand Therapists, the Jamar dynamometer was set at the second handle space when only one handle position is used (Fess, 1992; Fess and Moran, 1981). Test-retest reliability of the mean of three grip strength measurement trials has yielded correlation coefficients of 0.80 or above (Mathiowetz et ai., 1984). Calibration of the Jamar dynamometer was checked before and after the study, as well as after every 30 participants, using the method recommended by Fess (1987). Prior to the study, calibration of the Jamar dynamometer model number 54251 resulted in a correlation coefficient of 0.9995. Upon completion of the study, the Jamar dynamometer model number 54251 was determined to be inaccurate to 0.9958. Fess' guidelines have established accuracy to 0.9994. In order to verify Fess' results, the Jamar dynamometer model number 54251 was sent to Tech Services of Jackson, MI. This model was deemed by Tech Services to be inaccurate by ± 4 lb. Their standard for accuracy requires ± 3 lb. All data collected using the Jamar dynamometer model number 54251 were thrown out. In place of the defective Jamar dynamometer, a second calibrated Jamar dynamometer (model number 10252232) was substituted and used by the remaining 11 participants. Prior to the study,
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the second Jamar dynamometer was calibrated with a correlation coefficient of 0.9999. After the data were collected, the same dynamometer was recalibrated with a coefficient of 0.9999. Compliance with the home exercise program was assessed through the use of an interview administered by the therapist, which asked the participants questions regarding home exercise frequency, performance and questions and obstacles regarding the exercise performance. Compliance was rated by the participants every week from 1 week post-operation to 6 weeks post-operation using a scale from 3 (very compliant/performed exercises 100% of the time) to 0 (noncompliant/never performed exercises). The total compliance score of the self report scale ranged from 0 to 18 (0, non-compliant; and 18, total compliance). At 6 weeks post-operation, the therapist rated understanding of the home program by having the participants demonstrate the 6-week post-operation exercises. The scale for the therapist's rating of knowledge was as follows: 3, no errors were made when demonstrating the exercises; 2, few errors were made when demonstrating the exercises; 1, many errors were made when demonstrating the exercises; and 0, patient was unable to perform exercises or did not show for treatment. By therapists rating patients' understanding of the home program, the compliance measurement was determined not to be confounded by lack of knowledge. The therapists rated the knowledge of 24 patients (73%) as a 3, eight patients (24%) as a 2 and only one patient (3%) rated 1. Confidence in the compliance rating was thus enhanced. 2.4. Procedures
During the pre-operative visit, the occupational therapists gathered data on demographics, occupational and medical history and EMG test results. At this time, the occupational therapists reviewed with the participants a brochure on carpal tunnel syndrome, the operational procedure and the home exercise program for the 1st week post-operation. The home exercise program
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consisted of active and passive motion of the digits every waking hour and active motion of the shoulder and elbow five times a day. Also during the pre-operative visit, initial measurements of pre-operative grip strength were taken by the occupational therapists. The measurement of grip strength was carried out according to the following protocol of the Society of American Hand Therapists (Stanley et aI., 1992). The participants were assessed while comfortably seated with the shoulder adducted, elbow flexed to 90° and the forearm in a neutral position. The dynamometer was held lightly around the readout dial by the therapist while the participant squeezed. The therapist said: 'Are you ready? Squeeze as hard as you can'. As the participant began to squeeze, the therapist said: 'Harder... Harder... Relax'. Three successive trials of the maximal grip strength, each preceded by the above instructions, were taken with the dynamometer set on the second handle position. A 15-s rest between each trial was allowed to prevent fatigue (Mathiowetz, 1990). The surgical procedure involved a standard open decompression of the median nerve through the carpal tunnel. After a standard closure with 5-0 Prolene, a bulky dressing was placed around the hand, wrist and forearm from the distal metacarpals to the proximal forearm.
2.4.1. Post-operative At 1 week post-operation, the bulky dressing was removed by the occupational therapists. The therapists also asked the participant to rate compliance with the home exercise program as previously described. Participant's compliance was measured every week thereafter, including during the 6 weeks post-operative visit. The participant was fitted with a wrist cock-up splint and instructed to wear the splint at all times, except four times a day to perform pressure massage and 10 repetitions of wrist flexion/extension exercises. With the splint on or the wrist slightly extended, the subject performed 10 repetitions of putty and hand gripper exercises. At 2 weeks post-operation, the sutures were removed by the therapist. The putty and hand gripper exercises were increased to 20 repetitions,
three-five times daily. The scar was to be massaged eight times a day or every hour. The participants were also instructed to use the splint only when lifting, pulling, or as needed. At 3-5 weeks post-operation, the participants were instructed to continue the same exercise and scar massage regimen as previously instructed. If scar tenderness persisted, other modalities, such as a scar pump or a mini-massager were used at this time. At 6 weeks post-operation grip strength was measured. Grip strength was measured using the protocol of the Society of American Hand Therapists previously described. Participants were also asked when they returned to work and whether they returned to light or heavy duty. The participant's self-rating of compliance was determined again at this visit. Also at this visit, the therapists asked the participant to perform the home exercises as a means of evaluating understanding of the home program.
2.5. Data analysis After the data were collected, the means of the three trials for grip strengths, both pre- and postoperation, were calculated. If each of the three measures for both the pre-operation and post-operation grip strength varied more than 15%, the data were discarded. The coefficient of variation was determined by dividing the standard deviation by the mean of three trials and multiplying the result by 100. The percent differences between the pre- and post-operative grip strengths were calculated by subtracting the pre-operative grip strength from the post-operative grip strength, dividing the result by the post-operative grip strength and then multiplying by 100. A positive percent difference indicated an increase in grip strength from the pre-operative value, while a negative value indicated a decrease in grip strength from the pre-operative value. The remaining data were analyzed using the Minitab Statistical software package for MacIntosh (Schaefer and Farber, 1992). The P-value to determine significance was 0.05. The following statistics were performed to answer the research questions pertaining to the 11
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grip strength participants. To answer the question 'does age affect the return of grip strength?', the ages of participants were categorized by the following age groups: 21-39, 40-52 and 53-65 years. An ANDVA was then used to determine the difference by age in grip strength return. The question 'does gender affect the return of grip strength?' was analyzed using a two-sample t-test. The question 'does occupation affect the return of grip strength?' was analyzed by classifying occupations according to the Dictionary of Occupational Titles (Department of Labor and Employment and Training Administration, 1991). The job categories were as follows: (a) professionaljtechnicaljmanagerial, (b) clerical and sales, (c) machine trades, (d) benchwork trades and (e) miscellaneous occupations. The difference in grip strength return by occupational categories was determined by using an ANDVA. The occupational categories were collapsed from a previous listing due to the small sample size. Therefore the use of an ANDVA was more appropriate.
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To answer the question 'does a participant's compliance with the occupational therapy exercise protocol affect the return of grip strength?' the participants' self report of compliance was correlated with percent difference in grip strength return. Compliance trends of all 35 participants were also studied using graphic analysis, as shown in Fig. 1. The question 'does the amount of time between carpal tunnel release surgery and return to work influence the return of grip strength following carpal tunnel release surgery?' was analyzed by calculating the number of days between the subjects' carpal tunnel release surgery and date of return to work for the 11 grip strength participants. This value was then correlated to the percent difference in grip strength return. 3. Results
This study explored the return of grip strength 6 weeks following carpal tunnel release surgery.
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Table 1 Mean grip strengths and percent difference Mean pre-operative strength
Mean post-operative strength
Mean percent difference
50.6381b
49.2121b
-6.0064%
Table 1 displays the means for pre-operative, post-operative and percent difference between the strength measurement for the 11 participants. These results were similar to the trend found in the 24 participants excluded from the grip strength study. For these participants, the mean pre-operative grip strength was 52.3 lb and the mean post-operative grip strength was 47.7 lb. The mean percent difference was - 1.7%. For the 11 participants, the ANOVA showed no significant difference in grip strength return
among the different age groups (F = 1.20, P = 0.351). The two sample t-test for the 11 participants indicated no significant difference in return of grip strength between males and females 6 weeks following carpal tunnel release surgery (t = 1.01, P = 0.34). When examining the effect of occupation on percent difference for the 11 participants, the ANOVA indicated no significant difference among the occupational categories (F = 0.98, P = 0.484). The correlation between compliance and percent difference in grip strength post-carpal tunnel release for the 11 participants yielded a value of - 0.426. This indicates a mild negative correlation (Munroe et aI., 1986). The correlation between the number of days from surgery to return to work and percent difference yielded a value of - 0.067. This indicates that there was minimal correlation. Fig. 2 compares the overall compliance of the
Total Compliance
Fig. 2. Compliance vs. percent difference in grip strength.
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11 participants and the percent difference for grip strength return. This graph illustrates that the participants with low compliance scores had a greater percentage of grip strength. Fig. 1, as previously mentioned, illustrates the compliance trends for all 35 participants. Of the 35 participants surveyed, 18 stated reasons for not complying with their home exercise program. As shown in the graph, work was the most significant barrier to compliance, with 61 % of the 18 respondents claiming work as a barrier by week 6. Additional barriers included were other (22%) and care for family or home (11 %). 4. Discussion The - 6% difference between pre-operative and post-operative grip strengths suggested that 6 weeks may not be enough time to allow for the natural healing process to occur following surgery. This corroborates the study performed by Gellman et al. (1989) which found grip strength to return to 73% of pre-operative level by 6 weeks. The fact that the results proved insignificant for age and gender indicated that perhaps these two variables do not impact grip strength return. The possibility that gender may not have an impact on grip strength conflicts with previous research completed by Leach et al. (1993). According to Leach et al. (1993) grip strength of men returned to the pre-operative level within 12 weeks, while the grip strength of women did not reach the pre-operative level until 26-52 weeks post-operatively. The findings of occupation and the amount of time between surgery and return to work did not significantly affect grip strength return. These findings conflicted with the study performed by Nancollas et al. (1995) as they found that occupationally caused crs had a slower post-operative recovery time. Repetitious jobs were also revealed to cause more overuse injuries and reduce the effectiveness of carpal tunnel release (Nancollas et aI., 1995). The low negative correlation between participant self report of compliance and percent difference of grip strength implied that the more compliant the participant was with the home ex-
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ercise program, the slower grip strength returned. This may be a reflection of the limited sample size. Unexpectedly, participants with the greatest amount of compliance with the home exercise program and who returned work soon after surgery, demonstrated the weakest grip strength. This could imply that the exercise program in association with returning to work may have been too strenuous to allow for ample recovery. When considering compliance with the home exercise program, it should be noted that the participants did not report pain or a lack of understanding as reasons for not performing their exercises. Barriers to compliance did include work, caring for family and other. The other category included such explanations as feeling ill, holidays and vacations. Of these barriers, work was the most reported, with responses increasing in frequency at week four of the study. This suggests that home exercise programs perhaps should be modified to accommodate return to work. 4.1. Limitations It is uncertain whether the convenient sample of carpal tunnel release participants in this study was representative of carpal tunnel release patients throughout the country. All participants were patients of one orthopaedic hand surgeon in the midwest. Time constraints limited gathering data from additional orthopaedic hand surgeons. Subject attrition was another limitation impacting this study. Several participants failed to attend their 6-week post-operative visit, thereby eliminating themselves from the study. The most significant limitation was the calibration of the original dynamometer. Due to the lack of calibration, data from 24 participants had to be disregarded. Following this incident, time constraints confined data collection to 11 additional participants. Although this restricted the sample size to a small number of participants creating tentative conclusions that cannot be generalized, it did allow maintenance of internal validity within the study. According to Jarjour et al. (1997), calibration of the dynamometer should be examined after every 30 participants in grip strength research. It is recommended by this group of re-
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searchers that the calibration of the dynamometer should be tested after every 15 participants and/or steps be taken to ensure proper handling of the dynamometer.
Lynn Surrey for his guidance during our data analysis. We offer a special thank you to Dr Klein and his team of occupational therapists for their willingness to participate in our study.
4.2. Summary
References
When grip strength was measured in a confined sample of 11 carpal tunnel release patients, 6 weeks appeared to be insufficient for grip strength to return to pre-operative levels. Possibly contributing to this negative percent difference in grip strength was a high rate of compliance with the home exercise program along with concurrent engagement in work activities. This data implied that compliance with the home exercise program does not necessarily lead to faster recovery of pre-operative grip strength 6 weeks post-carpal tunnel release surgery. These conclusions are to be considered tentative and cannot be generalized because of the small sample size used in this study. The following recommendations are made in response to the findings in this study: (i) to allow for optimal recovery, insurance companies should further explore the need to reimburse occupational therapy services for greater than 6 weeks; (ii) patient compliance should not be confused with patient understanding; and (iii) home exercise programs should be adjusted according to the work demands of each patient. Suggestions for further research include checking the calibration of the dynamometer at the initiation of the study, after every 15 participants and at the conclusion of the study. Future research projects should focus on the return of grip strength, while adjusting the home exercise program according to the current work schedule of the participants.
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Acknowledgements We, the authors, would like to express our thanks to our research advisor, Dr Penny Moyers, EdD, OTR, FAOTA, CRT, for her continuous support and guidance throughout our research project. She has encouraged and challenged us as students, researchers and future occupational therapists. We would also like to acknowledge Dr
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Kellor M, Frost J, Silberberg N, Iversen I, Cummings R. Hand strength and dexterity. Am J Occup Ther 1971;25:77-83. Leach WJ, Esler C, Scott TD. Grip strength following carpal tunnel decompression. J Hand Surg 1993;18B(6):750-752. Levine DW, Simmons BP, Koris MJ, Daltroy LH, Hohl GG, Fossel AH, Katz IN. A self-administered questionnaire for the assessment of severity of symptoms and functional status in carpal tunnel syndrome. J Bone Jt Surg 1993;75A(I1):1585-1592. Mathiowetz V. Use of three trials on grip and pinch strength measurements. J Hand Ther 1990;3:195-198. Mathiowetz V, Weber K, Volland G, Kashman N. Reliability and validity of grip and pinch strength evaluations. J Hand Surg 1984;9A(2):222-226. Melhorn JM. CTD: Carpal tunnel syndrome, the facts and myths. Kansas Med 1994;189-192. Munroe BH, Visitainer MA, Page EB. Statistical methods for health care research. Philadelphia, PA: JB Lippincott, 1986. Nancollas MP, Peimer CA, Wheeler DR, Sherwin FS. Longterm results of carpal tunnel release. J Hand Surg (Br Eur Vol) 1995;20B(4):470-474. Norkin CC, Levangie PK Joint structure and function: A comprehensive analysis. Philadelphia, PA: FA Davis, 1992. Oda S, Moritani T. Movement-related cortical potentials during handgrip contractions with special reference to force and electromyogram bilateral deficit. Eur J Appl Physiol 1995;72:1-5.
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Rosenbaum RB, Ochoa JL. Surgical treatment of carpal tunnel syndrome. Carpal tunnel syndrome and other disorders of the median nerve. Stoneham, MA: Butterworth-Heinemann, 1993:263-281. Schaefer KL, Farber E. The student edition of Minitab. Edition 8 for MacIntosh. Reading, MS: Addison-Wesley, 1992. Schmidt RT, Toews JV. Grip strength as measured by the Jamar dynamometer. Arch Phys Med Rehabil 1970; 51:321-327. Sotereanos DG, Mitsionis GJ, Giannakopoulos PN, Tomaino MM, Herndon JH. Perilunate dislocation and fracture dislocation: A critical analysis of the volar-dorsal approach. J Hand Surg 1997;22A(1):49-55. Srinivasan VB, Matthews JP. Results of scaphotrapeziotrapezoid fusion for isolated idiopathic arthritis. J Hand Surg 1996;21B(3):378-380. Stanley BG, Tribuzi SM, Wolf SL. Concepts in hand rehabilitation. Philadelphia, PA: FA Davis, 1992. Tountas CP, MacDonald CJ, Meyerhoff JD, Bihrle DM. Carpal tunnel syndrome. A review of 507 patients. Minnesota Med 1983;66(8):479-482. Waggoner CD, LeLieuvre RB. A method to increase compliance to exercise regimes in rheumatoid arthritis patients. J Behav Med 1981;4:191-201.
ELSEVIER
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Student paper
The relationship of compliance and grip strength return post-carpal tunnel release surgery T.L. Bamowski, S.c. Blessinger, K.J. Britton, K.E. Flanagan, P.A. Mieling* , M.N. Ptacek, P.A. Moyers Graduate Program in Occupational Therapy, University of Indianapolis, Indianapolis, IN, USA Received 25 April 1997; accepted 1 July 1997
Abstract This study examined the relationship of compliance and grip strength return 6 weeks post-carpal tunnel release surgery on a sample of 11 factory workers residing in the midwest. The percent difference between pre-operative and post-operative grip strengths was - 6.00%. An ANOVA ruled out age as a significant factor in grip strength return (F = 1.20, P = 0.351). A two sample t-test for gender differences in return of grip strength proved insignificant as well (t = 1.01, P = 0.351). The low negative correlation between participant self-report of compliance and percent difference of grip strength was - 0.426. Work was reported as the most significant barrier to compliance. Results of this study suggested that 6 weeks of occupational therapy may not be sufficient for recovery to pre-operational grip strength status. Participants with the greatest amount of compliance in combination with returning to work soon after surgery demonstrated the weakest grip strength. This result implied that the exercise program in association with returning to work may have been too strenuous. Return to work and resulting work demands should be taken into consideration when prescribing home exercise programs. These conclusions are to be considered tentative and cannot be generalized because of the small sample size used to generate the data in this study. © 1998 Published by Elsevier Science "Ireland Ltd Keywords: Jamar dynamometer; Compliance; Grip strength
* Corresponding author, Graduate Programs in Occupational Therapy, University of Indianapolis, 1400 East Hanna Avenue, Indianapolis, IN 46227, USA. Tel.: +13177883432; fax: +13177883480.
1051-9815/98/$19.00 1998 Published by Elsevier Science Ireland Ltd. All rights reserved. PH S1051-9815(97)10026-2
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1. Introduction This study examined the return of grip strength and the compliance of participants with treatment following carpal tunnel release surgeI)'. After carpal tunnel surgeI)' is performed, many patients become concerned with the return of their grip strength as insurance policies generally limit payment for therapy sessions. Insurance companies are asking for the implications of the injuI)' in terms of medical costs and disability, for determination of appropriate goals for the treatment program and for expectation regarding return to functional performance (Jarjour et aI., 1997). Studies need to establish a post-operative time line that provides therapists and third-party payers with a guide to grip strength recoveI)'. An understanding of the return of grip strength will assist employers in gauging when employees may return to work and determining job modifications needed to accommodate any weaknesses in grip (Nancollas et aI., 1995). This study analyzed the effects of age, gender, occupation and return to work on grip strength recoveI)' following carpal tunnel release surgeI)'. Additionally, the relationship between grip strength recoveI)' and compliance with home exercise programs was studied. 1.1. Review of the literature
Cumulative trauma disorder (Cm) is often described as being related to occupational factors that regularly develop over time as a result of repetitive work actions. Carpal tunnel syndrome is the most commonly described and diagnosed condition of cm (Melhorn, 1994). Carpal Tunnel Syndrome (CTS) is a nerve entrapment syndrome in the upper limb, which occurs in 0.1 % of the population and 1-5% of workers in certain occupations (Levine et aI., 1993). The pathophysiology of CTS involves the compression of the median nerve in the palmer aspect of the wrist between the flexor tendons of the forearm muscles and the transverse superficial carpal ligament (Melhorn, 1994). The persistent swelling of the flexor tendons decreases the vascular supply to the median nerve. The compromised vasculature decreases the oxygen and nutrient supply to the
median nerve; therefore the nerve slowly loses the ability to transmit nerve impulses. As a result, scars and fibrous tissue develop within the nerve sheath. Depending upon the stage of injuI)', alterations to the nerve and muscles may be permanent (Melhorn, 1994). There have been reports of reduction in grip strength following carpal tunnel release surgeI)' (Gartsman et aI., 1986; Leach et al., 1993; Melhorn, 1994). Grip strength may be affected in several ways after carpal tunnel decompression. The discomfort of the surgical scar reduces the strength of the hand as well as creating muscle weakness due to several weeks of disuse (Leach et aI., 1993). A direct relationship has also been found between widening of the transverse carpal arch and loss of grip strength (Gartsman et aI., 1986). The study by Gartsman et al. revealed an average decrease of 12% in grip strength with widening of the carpal arch. Strength loss can also be explained by 'bow-stringing' of the flexor tendons caused as the result of the division of the transverse carpal ligament. Bow-stringing diminishes grip strength by altering the lever arm (Gartsman et aI., 1986). Atrophy of the thenar and hypothenar muscles after carpal tunnel release and decreased sensation are other possible causes of the decrease in grip strength (Norkin and Levangie, 1992). A study performed by Fissette et al. (1981) compared grip strength after surgeI)'. The results from their sample showed that participants consistently had stronger grips at 3, 6 and 9 months post-surgery. Rosenbaum and Ochou (1993) criticized the Fissette study by pointing out that there were no pre-operative data to compare the postoperative strength measurements. Studies have found a high correlation between grip strength and age (Mathiowetz et al., 1984; Kellor et aI., 1971; Schmidt and Toews, 1970). Limited research exists addressing age as a significant variable in the return of grip strength following carpal tunnel surgeI)'. Gender has been found to affect the return of grip strength following carpal tunnel decompression (Leach et aI., 1993). Leach et al. found that, in addition to the grip strength of men exceeding the grip strength of women pre-operatively, men
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also have a quicker return rate for grip strength than do women. The grip strength of men returned to the pre-operative level within 12 weeks, while the grip strength of women did not reach the pre-operative level until 26-52 weeks post-operatively (Leach et aI., 1993). Nancollas et ai. (1995) found a correlation between occupationally caused CTS and length of recovery time. If the carpal tunnel syndrome was occupationally caused, a longer recovery time existed. Long-term results following carpal tunnel release, however, were reported to be no different between subjects with occupationally caused carpal tunnel syndrome and non-occupationally caused carpal tunnel syndrome (Nancollas et aI., 1995). Repetitious jobs, according to Nancollas et aI., caused more overuse injuries and reduced the effectiveness of carpal tunnel release. Clearly, occupation does play a role in the incidence of CTS and the length of recovery following carpal tunnel release. Work-related carpal tunnel syndrome represents 47% of all carpal tunnel syndrome cases (Cummings et aI., 1989). In a study conducted by Tountas et ai. (1983), persons with carpal tunnel syndrome with treatment reimbursed by worker's compensation were less likely to have good postoperative results. The average return-to-work time was 12 weeks for subjects with worker's compensation (Tountas et aI., 1983). Subject" who presented with other forms of reimbursement returned to work within 3 weeks (Higgs et aI., 1995). Due to the fact that all of the subjects in this study were receiving worker's compensation, the effect of worker's compensation on the return of grip strength was not examined. This research project examined whether patient compliance would have an effect on the return of grip strength post-carpal tunnel release surgery. Measuring compliance to treatment plans can be a difficult task and has been a topic of debate in the literature. It has been shown, for example, that self-reports of compliance to medication treatment only identified 50% of non-compliant subjects (Haynes et aI., 1976). Other researchers have stated that self-reported follow through of treatment plans is an appropriate measure of compliance (Furth et aI., 1994).
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Questioning the authenticity of the patient's self-report of compliance assumes that the therapist's goals may not be the same as the patient's goals (Furth et aI., 1994). Setting mutual goals needs to be made a priority in order to motivate the patient to be compliant. Compliance is an important issue to consider as payers and practitioners rely on the patient's compliance to the treatment plan in order to ensure successful healing. The research of Waggoner and LeLieuvre (1981) indicated that self-reports coupled with other methods of measurement may be a more accurate way of measuring compliance. More recently, a method of assessment was designed and tested based on self-reported ratings of exercise compliance and therapist-reported ratings of the patient's exercise proficiency (Codori et al., 1992). The hypothesis was that if a positive correlation between the two ratings could be found, the measure of compliance could be considered reliable. Indeed, the researchers did find a positive correlation and commented on the importance of correlating multiple measurements in future research. Codori et al. (1992) also gave some suggestions in soliciting more authentic self-reports from patients. The patients in the study were encouraged to be honest, told to be honest and ensured that their responses would be anonymous. Codori at al. emphasized the importance of the patient feeling safe in revealing the truth. The patients need to be assured, for instance, that reporting a lack of compliance would not be held against him/her in a worker's compensation claim. In order to alleviate any feelings of threat, Codori et al. suggested mentioning to the patient that no one is perfect at complying and that it would be incredulous to expect someone to be 100% compliant. An extensive literature review on compliance in patients with rheumatoid arthritis was conducted by Feinberg (1988). Feinberg found that the most significant factor in patient compliance was the patient-practitioner relationship and that the practitioner's tone of voice and affect influenced the patient's perception of the relationship. If the practitioner presented him/herself with a positive tone, for example, the patient would be more
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likely to comply based on a more positive perception of the relationship. Additional significant factors in patient compliance included the patient's past experience and the patient's understanding of the reasoning behind the treatment prescribed (Feinberg, 1988). Although past research has examined the retum of grip strength following carpal tunnel decompression for patients in Europe (Leach et aI., 1993), little research has been conducted within the US. Gellman et ai. (1989) found grip strength to return to 73% of pre-operative grip strength by 6 weeks post-operatively. It is important that the knowledge base regarding the relationship between compliance and grip strength return following carpal tunnel release surgery be explored. Occupational therapists need to be aware of the factors that influence grip strength return following carpal tunnel release surgery in order to effectively set treatment goals. Insurance and third-party payers also need to understand the factors that influence grip strength return following carpal tunnel release in order to validate their reimbursement policies dictating the payment of limited numbers of occupational therapy treatment sessions. 1.2. Research questions
This study investigated the following questions:
(i) What is the percent difference between pre-
operative grip strength and post-operative grip strength 6 weeks following carpal tunnel release surgery? (ii) Does age affect the return of grip strength? (iii) Does gender affect the return of grip strength? (iv) Does occupation affect the return of grip strength? (v) Does the participant's compliance with the occupational therapy treatment protocol affect the return of grip strength? (vi) Does the amount of time between carpal tunnel release surgery and return to work influence the return of grip strength? 2. Materials and methods 2.1. Subjects
A sample of convenience of 36 persons partici-
pated in this study. Participants were carpal tunnel release surgery patients of an orthopaedic hand surgeon and two occupational therapists practicing in the midwest. The occupational therapists employed by the surgeon collected and provided the data to the researchers. Of the 36 participants, one was excluded due to scores of greater than 15% in the coefficient of variation. A coefficient of variation greater than 15% may demonstrate that the participants failed to give consistent effort during the grip strength trials (Bechtol, 1954). Another 24 participants were excluded as a result of having been tested with a dynamometer which was calibrated after 30 participants with a coefficient of 0.9958. The guidelines of Fess (1987) have established accuracy to 0.9994. A sample size of 11 grip strength participants remained. Other researchers have produced significant post-operative studies with limited sample sizes (Oda and Moritani, 1995; Sotereanos et al., 1997; Srinivasan and Matthews, 1996). The compliance data of the excluded 24 were used in the study. The 35 participants used to study compliance in this study were a minimum age of 18 years, male or female, and residing in the midwest. Participants were diagnosed with carpal tunnel syndrome by EMG tests conducted by a neurologist. Participants excluded from initial participation in this study were those with diagnoses of arthritis and/or diabetes mellitus, or previous surgery for cumulative trauma disorders on the same arm (Al-Qattan et al., 1994; Leach et aI., 1993). If a participant had a bilateral diagnosis of carpal tunnel syndrome, both extremities were treated as separate participants. Of the 11 grip strength participants, six were female and five were male. Nine participants were right-hand dominant and two were left-hand dominant. Five participants had carpal tunnel release surgery performed on the right hand and six had surgery on the left hand. Participants were all employed in factories. Positions varied from managerial work to benchwork and assembly line production, as classified by The Dictionary of Occupational Titles (Department of Labor and Employment and Training Administration, 1991). The mean age of participants was 48.3 years. All par-
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ticipants were receiving workman's compensation benefits.
2.2. Variables The dependent variable in this study was grip strength return, defined as the percent difference between pre-operative grip strength and post-operative grip strength 6 weeks following carpal tunnel release surgery. Independent variables included age, gender, occupation, compliance with treatment protocol and return to work following carpal tunnel release surgery.
2.3. Instruments Grip strength was measured using two standardized adjustable-handle Jamar dynamometers, model number 54251 and 10252232, respectively. As recommended by the American Society of Hand Therapists, the Jamar dynamometer was set at the second handle space when only one handle position is used (Fess, 1992; Fess and Moran, 1981). Test-retest reliability of the mean of three grip strength measurement trials has yielded correlation coefficients of 0.80 or above (Mathiowetz et ai., 1984). Calibration of the Jamar dynamometer was checked before and after the study, as well as after every 30 participants, using the method recommended by Fess (1987). Prior to the study, calibration of the Jamar dynamometer model number 54251 resulted in a correlation coefficient of 0.9995. Upon completion of the study, the Jamar dynamometer model number 54251 was determined to be inaccurate to 0.9958. Fess' guidelines have established accuracy to 0.9994. In order to verify Fess' results, the Jamar dynamometer model number 54251 was sent to Tech Services of Jackson, MI. This model was deemed by Tech Services to be inaccurate by ± 4 lb. Their standard for accuracy requires ± 3 lb. All data collected using the Jamar dynamometer model number 54251 were thrown out. In place of the defective Jamar dynamometer, a second calibrated Jamar dynamometer (model number 10252232) was substituted and used by the remaining 11 participants. Prior to the study,
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the second Jamar dynamometer was calibrated with a correlation coefficient of 0.9999. After the data were collected, the same dynamometer was recalibrated with a coefficient of 0.9999. Compliance with the home exercise program was assessed through the use of an interview administered by the therapist, which asked the participants questions regarding home exercise frequency, performance and questions and obstacles regarding the exercise performance. Compliance was rated by the participants every week from 1 week post-operation to 6 weeks post-operation using a scale from 3 (very compliant/performed exercises 100% of the time) to 0 (noncompliant/never performed exercises). The total compliance score of the self report scale ranged from 0 to 18 (0, non-compliant; and 18, total compliance). At 6 weeks post-operation, the therapist rated understanding of the home program by having the participants demonstrate the 6-week post-operation exercises. The scale for the therapist's rating of knowledge was as follows: 3, no errors were made when demonstrating the exercises; 2, few errors were made when demonstrating the exercises; 1, many errors were made when demonstrating the exercises; and 0, patient was unable to perform exercises or did not show for treatment. By therapists rating patients' understanding of the home program, the compliance measurement was determined not to be confounded by lack of knowledge. The therapists rated the knowledge of 24 patients (73%) as a 3, eight patients (24%) as a 2 and only one patient (3%) rated 1. Confidence in the compliance rating was thus enhanced. 2.4. Procedures
During the pre-operative visit, the occupational therapists gathered data on demographics, occupational and medical history and EMG test results. At this time, the occupational therapists reviewed with the participants a brochure on carpal tunnel syndrome, the operational procedure and the home exercise program for the 1st week post-operation. The home exercise program
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consisted of active and passive motion of the digits every waking hour and active motion of the shoulder and elbow five times a day. Also during the pre-operative visit, initial measurements of pre-operative grip strength were taken by the occupational therapists. The measurement of grip strength was carried out according to the following protocol of the Society of American Hand Therapists (Stanley et aI., 1992). The participants were assessed while comfortably seated with the shoulder adducted, elbow flexed to 90° and the forearm in a neutral position. The dynamometer was held lightly around the readout dial by the therapist while the participant squeezed. The therapist said: 'Are you ready? Squeeze as hard as you can'. As the participant began to squeeze, the therapist said: 'Harder... Harder... Relax'. Three successive trials of the maximal grip strength, each preceded by the above instructions, were taken with the dynamometer set on the second handle position. A 15-s rest between each trial was allowed to prevent fatigue (Mathiowetz, 1990). The surgical procedure involved a standard open decompression of the median nerve through the carpal tunnel. After a standard closure with 5-0 Prolene, a bulky dressing was placed around the hand, wrist and forearm from the distal metacarpals to the proximal forearm.
2.4.1. Post-operative At 1 week post-operation, the bulky dressing was removed by the occupational therapists. The therapists also asked the participant to rate compliance with the home exercise program as previously described. Participant's compliance was measured every week thereafter, including during the 6 weeks post-operative visit. The participant was fitted with a wrist cock-up splint and instructed to wear the splint at all times, except four times a day to perform pressure massage and 10 repetitions of wrist flexion/extension exercises. With the splint on or the wrist slightly extended, the subject performed 10 repetitions of putty and hand gripper exercises. At 2 weeks post-operation, the sutures were removed by the therapist. The putty and hand gripper exercises were increased to 20 repetitions,
three-five times daily. The scar was to be massaged eight times a day or every hour. The participants were also instructed to use the splint only when lifting, pulling, or as needed. At 3-5 weeks post-operation, the participants were instructed to continue the same exercise and scar massage regimen as previously instructed. If scar tenderness persisted, other modalities, such as a scar pump or a mini-massager were used at this time. At 6 weeks post-operation grip strength was measured. Grip strength was measured using the protocol of the Society of American Hand Therapists previously described. Participants were also asked when they returned to work and whether they returned to light or heavy duty. The participant's self-rating of compliance was determined again at this visit. Also at this visit, the therapists asked the participant to perform the home exercises as a means of evaluating understanding of the home program.
2.5. Data analysis After the data were collected, the means of the three trials for grip strengths, both pre- and postoperation, were calculated. If each of the three measures for both the pre-operation and post-operation grip strength varied more than 15%, the data were discarded. The coefficient of variation was determined by dividing the standard deviation by the mean of three trials and multiplying the result by 100. The percent differences between the pre- and post-operative grip strengths were calculated by subtracting the pre-operative grip strength from the post-operative grip strength, dividing the result by the post-operative grip strength and then multiplying by 100. A positive percent difference indicated an increase in grip strength from the pre-operative value, while a negative value indicated a decrease in grip strength from the pre-operative value. The remaining data were analyzed using the Minitab Statistical software package for MacIntosh (Schaefer and Farber, 1992). The P-value to determine significance was 0.05. The following statistics were performed to answer the research questions pertaining to the 11
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grip strength participants. To answer the question 'does age affect the return of grip strength?', the ages of participants were categorized by the following age groups: 21-39, 40-52 and 53-65 years. An ANDVA was then used to determine the difference by age in grip strength return. The question 'does gender affect the return of grip strength?' was analyzed using a two-sample t-test. The question 'does occupation affect the return of grip strength?' was analyzed by classifying occupations according to the Dictionary of Occupational Titles (Department of Labor and Employment and Training Administration, 1991). The job categories were as follows: (a) professionaljtechnicaljmanagerial, (b) clerical and sales, (c) machine trades, (d) benchwork trades and (e) miscellaneous occupations. The difference in grip strength return by occupational categories was determined by using an ANDVA. The occupational categories were collapsed from a previous listing due to the small sample size. Therefore the use of an ANDVA was more appropriate.
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To answer the question 'does a participant's compliance with the occupational therapy exercise protocol affect the return of grip strength?' the participants' self report of compliance was correlated with percent difference in grip strength return. Compliance trends of all 35 participants were also studied using graphic analysis, as shown in Fig. 1. The question 'does the amount of time between carpal tunnel release surgery and return to work influence the return of grip strength following carpal tunnel release surgery?' was analyzed by calculating the number of days between the subjects' carpal tunnel release surgery and date of return to work for the 11 grip strength participants. This value was then correlated to the percent difference in grip strength return. 3. Results
This study explored the return of grip strength 6 weeks following carpal tunnel release surgery.
70 r-------~----------------------------
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T.L. Barnowski et at. / Work 10 (1998) 181 - 191
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Table 1 Mean grip strengths and percent difference Mean pre-operative strength
Mean post-operative strength
Mean percent difference
50.6381b
49.2121b
-6.0064%
Table 1 displays the means for pre-operative, post-operative and percent difference between the strength measurement for the 11 participants. These results were similar to the trend found in the 24 participants excluded from the grip strength study. For these participants, the mean pre-operative grip strength was 52.3 lb and the mean post-operative grip strength was 47.7 lb. The mean percent difference was - 1.7%. For the 11 participants, the ANOVA showed no significant difference in grip strength return
among the different age groups (F = 1.20, P = 0.351). The two sample t-test for the 11 participants indicated no significant difference in return of grip strength between males and females 6 weeks following carpal tunnel release surgery (t = 1.01, P = 0.34). When examining the effect of occupation on percent difference for the 11 participants, the ANOVA indicated no significant difference among the occupational categories (F = 0.98, P = 0.484). The correlation between compliance and percent difference in grip strength post-carpal tunnel release for the 11 participants yielded a value of - 0.426. This indicates a mild negative correlation (Munroe et aI., 1986). The correlation between the number of days from surgery to return to work and percent difference yielded a value of - 0.067. This indicates that there was minimal correlation. Fig. 2 compares the overall compliance of the
Total Compliance
Fig. 2. Compliance vs. percent difference in grip strength.
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11 participants and the percent difference for grip strength return. This graph illustrates that the participants with low compliance scores had a greater percentage of grip strength. Fig. 1, as previously mentioned, illustrates the compliance trends for all 35 participants. Of the 35 participants surveyed, 18 stated reasons for not complying with their home exercise program. As shown in the graph, work was the most significant barrier to compliance, with 61 % of the 18 respondents claiming work as a barrier by week 6. Additional barriers included were other (22%) and care for family or home (11 %). 4. Discussion The - 6% difference between pre-operative and post-operative grip strengths suggested that 6 weeks may not be enough time to allow for the natural healing process to occur following surgery. This corroborates the study performed by Gellman et al. (1989) which found grip strength to return to 73% of pre-operative level by 6 weeks. The fact that the results proved insignificant for age and gender indicated that perhaps these two variables do not impact grip strength return. The possibility that gender may not have an impact on grip strength conflicts with previous research completed by Leach et al. (1993). According to Leach et al. (1993) grip strength of men returned to the pre-operative level within 12 weeks, while the grip strength of women did not reach the pre-operative level until 26-52 weeks post-operatively. The findings of occupation and the amount of time between surgery and return to work did not significantly affect grip strength return. These findings conflicted with the study performed by Nancollas et al. (1995) as they found that occupationally caused crs had a slower post-operative recovery time. Repetitious jobs were also revealed to cause more overuse injuries and reduce the effectiveness of carpal tunnel release (Nancollas et aI., 1995). The low negative correlation between participant self report of compliance and percent difference of grip strength implied that the more compliant the participant was with the home ex-
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ercise program, the slower grip strength returned. This may be a reflection of the limited sample size. Unexpectedly, participants with the greatest amount of compliance with the home exercise program and who returned work soon after surgery, demonstrated the weakest grip strength. This could imply that the exercise program in association with returning to work may have been too strenuous to allow for ample recovery. When considering compliance with the home exercise program, it should be noted that the participants did not report pain or a lack of understanding as reasons for not performing their exercises. Barriers to compliance did include work, caring for family and other. The other category included such explanations as feeling ill, holidays and vacations. Of these barriers, work was the most reported, with responses increasing in frequency at week four of the study. This suggests that home exercise programs perhaps should be modified to accommodate return to work. 4.1. Limitations It is uncertain whether the convenient sample of carpal tunnel release participants in this study was representative of carpal tunnel release patients throughout the country. All participants were patients of one orthopaedic hand surgeon in the midwest. Time constraints limited gathering data from additional orthopaedic hand surgeons. Subject attrition was another limitation impacting this study. Several participants failed to attend their 6-week post-operative visit, thereby eliminating themselves from the study. The most significant limitation was the calibration of the original dynamometer. Due to the lack of calibration, data from 24 participants had to be disregarded. Following this incident, time constraints confined data collection to 11 additional participants. Although this restricted the sample size to a small number of participants creating tentative conclusions that cannot be generalized, it did allow maintenance of internal validity within the study. According to Jarjour et al. (1997), calibration of the dynamometer should be examined after every 30 participants in grip strength research. It is recommended by this group of re-
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searchers that the calibration of the dynamometer should be tested after every 15 participants and/or steps be taken to ensure proper handling of the dynamometer.
Lynn Surrey for his guidance during our data analysis. We offer a special thank you to Dr Klein and his team of occupational therapists for their willingness to participate in our study.
4.2. Summary
References
When grip strength was measured in a confined sample of 11 carpal tunnel release patients, 6 weeks appeared to be insufficient for grip strength to return to pre-operative levels. Possibly contributing to this negative percent difference in grip strength was a high rate of compliance with the home exercise program along with concurrent engagement in work activities. This data implied that compliance with the home exercise program does not necessarily lead to faster recovery of pre-operative grip strength 6 weeks post-carpal tunnel release surgery. These conclusions are to be considered tentative and cannot be generalized because of the small sample size used in this study. The following recommendations are made in response to the findings in this study: (i) to allow for optimal recovery, insurance companies should further explore the need to reimburse occupational therapy services for greater than 6 weeks; (ii) patient compliance should not be confused with patient understanding; and (iii) home exercise programs should be adjusted according to the work demands of each patient. Suggestions for further research include checking the calibration of the dynamometer at the initiation of the study, after every 15 participants and at the conclusion of the study. Future research projects should focus on the return of grip strength, while adjusting the home exercise program according to the current work schedule of the participants.
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Acknowledgements We, the authors, would like to express our thanks to our research advisor, Dr Penny Moyers, EdD, OTR, FAOTA, CRT, for her continuous support and guidance throughout our research project. She has encouraged and challenged us as students, researchers and future occupational therapists. We would also like to acknowledge Dr
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