|Year : 2018 | Volume
| Issue : 3 | Page : 248-253
Influence of occupation and hand dominance on the thickness of pronator quadratus muscle among apparently healthy volunteers in a Nigerian population
Anthony Chukwuka Ugwu1, Benjamin Effiong Udoh2, Alhaji Modu Ali3, Mohammed Yusuf Mohammed4, Umar Abubakar5, Mohammed Abba6
1 Department of Radiography and Radiological Sciences, Faculty of Health Sciences and Technology, Nnamdi Azikwe University, Awka, Anambra State, Nigeria
2 Department of Radiography and Radiological Sciences, Faculty of Allied Medical Sciences, University of Calabar, Calabar, Cross River State, Nigeria
3 Department of Radiology, Federal Neuro Psychiatric Hospital, Maiduguri, Borno State, Nigeria
4 Department of Radiology, University of Maiduguri Teaching Hospital, Maiduguri, Borno State, Nigeria
5 Department of Radiography, College of Health Sciences, Usmanu Danfodio University, Sokoto, Sokoto State, Nigeria
6 Department of Radiography, Faculty of Health Sciences, Bayero University, Kano, Kano State, Nigeria
|Date of Web Publication||25-Sep-2018|
Mr. Alhaji Modu Ali
Department of Radiology, Federal Neuro Psychiatric Hospital Maiduguri, Maiduguri, Borno State
Source of Support: None, Conflict of Interest: None
OBJECTIVES: The aim of this study was to sonographically measure and compare the pronator quadratus muscle thickness (PQMT) in apparently healthy volunteers between two occupational groups and to assess the influence of hand dominance on the PQMT.
METHODS: A total of 180 apparently healthy volunteers were enrolled in the study. The volunteers were grouped into repetitive (90) and nonrepetitive (90) workgroups. They were scanned with a B-mode ultrasound machine and linear transducer.
RESULTS: The mean PQMT was significantly higher (P < 0.05) in the repetitive workgroup than in nonrepetitive workgroups. Similarly, a significant difference in mean PQMT was observed between dominant and nondominant hands in the repetitive workgroups (P < 0.05).
CONCLUSION: The mean PQMT among repetitive workgroup is significantly higher when compared with nonrepetitive workgroups in the study area.
Keywords: Nonrepetitive work, pronator quadratus muscle, repetitive work, sonography, thickness
|How to cite this article:|
Ugwu AC, Udoh BE, Ali AM, Mohammed MY, Abubakar U, Abba M. Influence of occupation and hand dominance on the thickness of pronator quadratus muscle among apparently healthy volunteers in a Nigerian population. Indian J Health Sci Biomed Res 2018;11:248-53
|How to cite this URL:|
Ugwu AC, Udoh BE, Ali AM, Mohammed MY, Abubakar U, Abba M. Influence of occupation and hand dominance on the thickness of pronator quadratus muscle among apparently healthy volunteers in a Nigerian population. Indian J Health Sci Biomed Res [serial online] 2018 [cited 2018 Dec 15];11:248-53. Available from: http://www.ijournalhs.org/text.asp?2018/11/3/248/242047
| Introduction|| |
The pronator quadratus muscle (PQM) is a small quadrilateral muscle attached to the anterior aspect of the distal one-sixth of the radius and ulna. The PQM is formed by two distinct layers; superficial and deep layers. The superficial layer is believed to be responsible for the pronation of the forearm and the hands in coordination with the pronator teres muscle, while the deep layer helps in stabilizing the distal radio-ulna joint. This muscle is covered by a well-defined fascia that prevents intermuscular communication and creates a distinct forearm space in which fluids accumulate. This feature contributes to the appearance of the “pronator quadratus sign” on lateral radiograph. This fat plane can be seen as a thin radiolucency on at least 90% of the normal lateral distal forearm radiographs.
This muscle may become overactive and shortened due to overuse from repetitive activities involving isometric contraction of the pronator muscles. A contracted PQM may not likely lead to an injury, but overactive and contracted pronator teres muscle can lead to pronator teres syndrome or median nerve injury which may indirectly lead to pronator quadratus (PQ) weakness or pronator syndrome. Moreover, this is mostly caused by the fracture or injuries involving the distal forearm., Other injuries to the forearm with no fracture (muscle strain, wringer injury) and infectious and inflammatory conditions (cellulitis, septic arthritis, or osteomyelitis) can result in swelling of the PQM or soft-tissue edema, resulting in PQ sign. The fat plane overlying the PQM on a lateral radiograph of the distal forearm is useful in the diagnosis of an undisplaced fracture of the radius and ulna with the help of PQ sign.
The PQ sign is visible on plain radiograph when fluids such as blood accumulate within this muscle and then becomes swollen, bulged anteriorly, and can displace the lucent fat plane., The degree of displacement can be quantified by measuring the distance between the fat plane and distal radius, which corresponds to the PQM thickness (PQMT). However, the reliability of the swollen PQM on plain radiography for the diagnosis of distal forearm fracture remains very low when compared to magnetic resonance imaging (MRI).
MRI has been stated to be the best, reliable, and recommended diagnostic imaging modality in the diagnosis of occult bone injury or anterior interosseous nerve injury, but the procedure is time-consuming, costly to procure, and maintain.
High-resolution B-mode ultrasound (US) therefore is a safe, cheap, noninvasive, precise, reproducible method and is very useful when there is a specific clinical question regarding a well-localized swelling. US permits accurate quantification of the PQMT, which is the measurement of the thickness of the muscle.
Studies have shown a strong correlation between PQMT and acute distal forearm injury., PQMT has also been shown to correlate with an occult bone injury. Moreover, this predictor will serve as a useful tool for the detection of occult bone injury which helps the clinician to more effectively identify the vulnerable individual who will benefit from aggressive intervention. However, there is a paucity of information on the role US in the quantification of the PQMT in the study area.
The aim of this study was to evaluate the PQMT in repetitive workgroups using high-resolution B-mode US and compare with PQMT in a nonrepetitive workgroup in the study area. Second was to assess the influence of hand dominance, age, and gender on PQMT.
| Methods|| |
This is a prospective, case–control study carried out at the department of radiology of the federal Neuro psychiatric hospital Maiduguri between December 2015 and July 2016. A total of 180 volunteers comprising 90 adult volunteers involved in routine, repetitive work and another 90 adult individuals that are not routinely involved in repetitive work were enrolled into this study.
The nonprobability (convenience) sampling method was adopted and volunteers who were apparently healthy adults were drawn from hospital staff, patient relation, students, and various occupational groups. The sample size was calculated using Cochran formula. Informed consent was obtained from all volunteers following a thorough explanation of the procedure and the study aims. Ethical approval was obtained from the Human Research Ethics Committee and Institutional Review Board of the XXX.
Volunteers' demographic and anthropometric variables were documented.
Apparently healthy individuals of either gender and aged 18–60 years were included in the study.
Individuals aged <18 years and >70 years or who were pregnant were excluded from the study. Those with an inflammatory condition of the distal forearm, a chronic systemic problem associated with the musculoskeletal system, and a history of major distal forearm trauma and surgery were also excluded from the study.
During the scanning, the volunteers sat and faced the Sonographer with the ipsilateral forearm fully supinated and placed on a rectangular foam pad with the hand relaxed and slightly tilted backward. The sonographic characteristics of the PQM were evaluated on sagittal and axial sonograms. The sagittal sonograms were used to measure the thickness of the radial part of the PQM, while the axial sonograms were used to measure the thickness of the interosseous and ulnar parts.,,
For the sagittal scanning, the transducer was placed perpendicular to the volar surface of the ipsilateral distal forearm with little pressure along the flexor carpi radialis tendon, and the maximum PQMT was measured at corresponding sites bilaterally [Figure 1].,, Since the sagittal image mainly represents the superficial layer of PQM on the volar side at the level of the radial cortex, we considered the correspondence to the radiographic PQ sign and measured the maximum thickness at this level [Figure 2].,,
|Figure 1: Position of the transducer for a sagittal image at distal forearm|
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For axial scanning, the transducer was placed distally adjacent to the distal radioulnar joint and moved proximally to get the maximum thickness of the PQM on the volar side [Figure 3]. Here, the maximum PQMT was measured at ulna and interosseous parts [Figure 4]. In each case, measurements were repeated twice and average results were recorded.
|Figure 3: Position of the transducer for an axial image at distal forearm|
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All sonographic examinations were performed using a Voluson P8 General electric US machine (GE medicals inc., New York, USA) and a linear array transducer (7–12 MHz; contact area, 9 mm × 43 mm) with custom preset for musculoskeletal sonography. In order to assess intraobserver reliability on the measured thickness, the sonographic measurements were repeated on the first fifty volunteers at 1-week interval.
Statistical analysis of the data was done using SPSS software version 22 (IBM corp., Armonk, New York, USA) for Windows. Group data were expressed as mean ± standard deviation (SD). To investigate the influence of occupation, gender, and hand dominance on PQMT, comparisons between repetitive and nonrepetitive workgroups and male and female volunteers were done using Mann–Whitney U-test, while the matched sample t-test was used to compare the mean PQMT on dominant and nondominant hands. To assess the influence of age, weight, height, and body mass index on the PQMT, Pearson's correlation was performed. Differences and associations were deemed significant if P < 0.05.
| Results|| |
There were 180 volunteers comprised of 90 volunteers (repetitive workgroups) with 61 males and 29 females (age range, 18–60 years; mean age ± SD, 35.07 ± 9.96 years). It comprises mainly of healthy individuals who are repeatedly involved in activities requiring hand grip as part of their routine activity (farmers, blacksmith, carpenter, bricklayers, plumbers, construction workers, etc.).
Another ninety volunteers (nonrepetitive workgroup), there were 51 males and 31 females (age range, 18–57 years; mean age ± SD, 29.06 ± 9.87 years). It comprised mainly of healthy individuals who are not repeatedly involved in activities requiring hand grip as part of their routine activity (students, homemakers, administrators, accountants, clinical staff, etc.).
Eighty-four (93.33%) volunteers had right-hand dominance, while 6 (6.67%) had left-hand dominance in the repetitive workgroup. Similarly, 87 (96.67%) volunteers had right-hand dominance, while 3 (3.43%) had left-hand dominance in the nonrepetitive workgroups. However, no volunteer was classified as ambidextrous.
Farmers constitute more than half (54.44%) of the repetitive workgroup, while blacksmith had the least proportion (1.11%). While in the nonrepetitive workgroup, students constituted the largest proportion (34.44%), while clinical staff had the least proportion (6.66%).
The mean PQMT values of the repetitive workgroup were significantly higher on both sides when compared with PQMT values in the nonrepetitive workgroup (P < 0.05). The mean values of the PQMT of the dominant and nondominant hands were 6.24 ± 1.16 mm and 5.53 ± 0.92 mm, respectively, for the repetitive workgroup. While the mean values of the PQMT for nonrepetitive workgroup were 5.01 ± 0.90 mm and 4.8 ± 0.82 mm for the dominant and nondominant hands, respectively [Table 1].
|Table 1: Sonographic comparison of the pronator quadratus muscle thickness in repetitive and nonrepetitive workgroups|
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The mean values of the PQMT on the dominant hand are significantly higher than the nondominant hands of the repetitive workgroup. However, there was no statistically significant difference in the mean PQMT between dominant and nondominant hands in the nonrepetitive workgroup (P = 0.515 and P = 0.247, respectively) [Table 2].
|Table 2: Mean pronator quadratus muscle thickness on dominant and nondominant hands|
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There was a moderate positive correlation between PQMT values of the dominant hands and the volunteer's age in both groups [Table 3].
|Table 3: Correlations between the mean pronator quadratus muscle thickness and some demographic variables in repetitive and non repetitive workgroups of volunteers|
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| Discussion|| |
The PQ muscle is a quadrilateral muscle with attachments at the distal volar aspect of the ulna and radius. It is reportedly a key soft tissue in the diagnosis of radiographically undetectable fractures., However, a lateral radiograph of the normal distal forearm does not always demonstrate this muscle.
The present study shows that the mean PQMT in the repetitive workgroup is higher than that in the nonrepetitive workgroup (P < 0.05). A significant difference in mean PQMT was also observed between the dominant and nondominant hands in the repetitive workgroup. However, there was no significant difference in mean PQMT between dominant and nondominant hand in the nonrepetitive workgroup.
In this study, the mean PQMT measures 5.68 and 4.97 mm for repetitive and nonrepetitive workgroups, respectively. This finding agrees with that of Sun et al. who reported a mean PQMT of 7.37 and 4.70 mm for fracture and healthy control groups, respectively. Similarly, Sasaki and Sugioka  reported a mean distance of <7 mm in 92% of 72 control group individuals in which pronator fat shadow has been detected and >7 mm in 93% of 29 recent distal radius fractures under the same condition. It has been concluded that the trauma to the distal forearm is strongly related to the increased PQMT. A similar finding has been reported by Zammit-Maempel et al. who reported a mean PQMT of 6.75 and 4.97 mm for fracture and control groups, respectively. However, Sun et al., Sasaki and Sugioka, and Zammit-Maempel et al., did not state the individuals' occupation. This might explain the reason for this variation in the mean PQMT.
The mean PQMT of the dominant hand in the present study was significantly higher than that of the nondominant hands in the repetitive workgroup. However, there was no significant difference in PQMT between dominant and nondominant hands of the nonrepetitive workgroup. The mean cross-wise difference in PQMT was 0.52 mm on the sagittal image and 0.60 mm on the axial sonograms for the repetitive group, but 0.30 and 0.34 mm on sagittal and axial sonograms, respectively, for the nonrepetitive group. The cross-wise difference is greater in the repetitive workgroup and also greater among male volunteers (P < 0.05). Sato et al. had earlier reported that the maximum PQMT among all volunteers had a significant difference between dominant and nondominant hands on each sonogram. Their mean cross-wise difference (0.4 and 0.53 mm for sagittal and axial images, respectively) is, however, lower compared to the present study. Researchers have stipulated that a cross-wise difference of >1.4 mm on the sagittal image and 1.5 mm on the axial image seemed to be adequate practical limits for detecting PQ thickening or pathology.
We suggest that the cross-wise difference in PQM between dominant and nondominant hands might need to be taken into account in healthy volunteers when a sonographic comparison of both hands is to be done. These results might be useful for sonographic comparison of PQ muscles when the clinician is interested in knowing the cause of pain, swelling, prono-supination disorders, and posttraumatic scar.
| Conclusion|| |
This study shows a statistically significant increase in PQMT in a repetitive workgroup when compared with nonrepetitive workgroup in the study area. Higher mean PQMT values were also seen among males in both groups. Increased mean PQMT values were also seen on the dominant hands in the repetitive workgroup. Therefore, occupation, gender, and hand dominance should be considered during sonographic evaluation of PQM in the diagnosis of occult fracture of the distal forearm or atrophied PQ due to anterior interosseous nerve pathology.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]
[Table 1], [Table 2], [Table 3]