Original Paper Received: September 1, 2014 Accepted after revision: December 31, 2014 Published online: March 5, 2015
Dig Surg 2015;32:112–116 DOI: 10.1159/000371859
Correlation between Abdominal Rectus Diastasis Width and Abdominal Muscle Strength Ulf Gunnarsson a Birgit Stark c Ursula Dahlstrand b Karin Strigård a
a
Department of Surgical and Perioperative Sciences, Umeå University, Umeå, b Department for Surgery, CLINTEC, Karolinska Institutet, Stockholm, and c Department for Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden
Abstract Background: Surgery for Abdominal Rectus Diastasis (ARD) is a controversial topic and some argue that it is solely an aesthetic problem. Many symptoms in these patients are indefinite, and no objective criteria have been established, indicating which patients are likely to benefit from surgery. This study investigated the correlation between preoperative assessment and intraoperative measurement of ARD width, and objective measurements of muscle strength. Methods: 57 patients undergoing surgery for ARD underwent preoperative assessment of ARD width by clinical measurement and CT scan, and thereafter intraoperative measurement. Abdominal muscle strength was investigated using the Biodex System 4 including flexion, extension and isometric measurements. Correlations were calculated by the Spearman test. Results: Intraoperative ARD width between the umbilicus and the symphysis correlated strongly with Biodex measurements during flexion (p = 0.007, R = –0.35) and isometric work load (p = 0.01, R = –0.34). The following measurements showed no correlation: between
© 2015 S. Karger AG, Basel 0253–4886/15/0322–0112$39.50/0 E-Mail [email protected] www.karger.com/dsu
muscle strength and BMI; muscle strength and waistline; or between muscle strength and ARD width above the umbilicus, assessed preoperatively at the outpatient clinic, by CT scan, or measured intraoperatively. Conclusion: There is a strong correlation between intraoperatively measured ARD width below the umbilicus and flexion and isometric abdominal muscle strength measured with the Biodex System 4. © 2015 S. Karger AG, Basel
Introduction
There is still controversy regarding surgery for abdominal rectus diastasis (ARD) [1]. The value of symptoms such as back pain, weak abdominal muscle strength and discomfort has not been specifically determined, and it has been questioned whether these are correlated to ARD or not. Outcome of surgery among the present patients show that several symptoms are relieved after surgery [2]. We urgently need tools that can predict functional outcome after surgery for ARD, and not just for evaluation of subjective symptoms. Such tools include validated questionnaires to measure pain before and after surgery such as the VHPQ (Ventral Hernia Pain QuesKarin Strigård Surgical Center NUS SE–907 50 Umeå (Sweden) E-Mail karin.strigard @ umu.se
Downloaded by: Stockholms Universitet 198.143.54.1 - 8/3/2015 4:35:25 PM
Key Words Rectus diastasis · ARD · Biodex System 4 · Muscle strength · Clinical symptoms
Fig. 1. Intraoperative picture of ARD. Width 4 cm below the umbilicus and 3 cm above. During dissection in top the markings for the lowest rib are visible.
In the present study, patients with symptoms from their ARD (≥3 cm above or below the umbilicus) were randomized to surgery with either a double-running suture technique (Quill) or a sublay mesh technique described in a previous paper [2]. Patients who did not fulfill inclusion criteria were not operated in the public system since this diagnosis is not seen as a disease. Inclusion time was between December 2009 and December 2012. The intended sample size was calculated on the premise that there is a clinically significant difference in one-year recurrence rate, measured with CT and/or clinically, between the two ARD surgical repair techniques, which was the primary endpoint of the background study. Functional complaints arising from the ARD were discomfort and/or painful tenderness. The abdominal outline with bulging of the lin-
ea alba are most commonly pronounced below the umbilicus in women after pregnancy [8]. Clinical assessment of the ARD as well as CT scan and Biodex System 4 muscle force measurements were performed prior to surgery. The ARD width was assessed preoperatively, using a tape measure, between the xiphoid process and the umbilicus and between the umbilicus and symphysis, in a relaxed supine position. One physician performed all measurements. The width of the diastasis in the upper and the lower midline was measured three times in each patient. The average of the three measurements was used in the analyses. The same measuring points were used when evaluating the CT scan as well as when measuring the width during surgery (fig. 1). CT scans were evaluated by two independent radiologists. The Biodex Multi-Joint System-4 Pro machine (Biodex®, Inc., Shirley, N.Y., USA) has a unit that makes it possible to test both back and abdominal muscle strength even if the individual muscle groups cannot be differentiated. Flexion, extension and isokinetic muscle strengths were measured and the results given in Newtonmeter (Nm). In the isokinetic test, there is a pre-designated maximal movement speed that cannot be exceeded. Maximal strength (peak torque) and maximal work are tested during the flexion and extension tests, 30°/s and 60°/s. In the test situation, the subject sits in a chair-like position with the hip at 90 degrees [7] (fig. 2). Anatomical landmarks are monitored to make it possible to reproduce the exact position in a retest situation. The body is secured with
Rectus Diastasis and Abdominal Muscle Strength
Dig Surg 2015;32:112–116 DOI: 10.1159/000371859
Material and Methods
113
Downloaded by: Stockholms Universitet 198.143.54.1 - 8/3/2015 4:35:25 PM
tionnaire) [3], VAS scales for self-evaluation of muscle strength [2], or the SF 36 [4]. VHPQ is a questionnaire validated for pain in the abdominal wall and its consequences in daily life. Another objective tool is the Biodex System for measurement of abdominal muscle strength, which has been validated for ARD [5] and shown to have excellent internal validity. If the symptoms from ARD emanate from a decrease in abdominal wall muscle strength, it should be possible to determine a correlation between the width of the ARD and abdominal muscle strength. As shown previously [6], the correlation between the ARD width estimated clinically using a tape measure and that estimated by CT scan is low. The intraoperative finding was regarded as the ‘true’ ARD width, and that correlated fairly well with preoperative clinical assessment using a tape measure. Using the Biodex System 4, patient muscle force is measured under flexion and extension at two different speeds as well as isometrically. In patients with ARD, flexion and isometric force results were the most reliable [5]. Extension may reflect the activation of muscles other than abdominal, and this test situation also appeared more complex for the patient to follow. In healthy volunteers, both flexion and extension testing seemed easier to perform than isometric testing. In another study evaluating patients with giant ventral hernia, isometric testing appeared to be the easiest [7]. Since different abdominal wall dysfunctions show different symptoms and problems, it is important to validate the Biodex System 4 for each specific type of abdominal wall muscle dysfunction. The purpose of this study was to investigate the relationship between preoperative assessment (clinical and CT-scan) and intraoperative ARD width measurements, and the relationship between ‘true’ ARD width and objective muscle strength using the Biodex System 4.
Table 1. ARD in cm; preoperative and intraoperative measurements with a tape and evaluation by CT scan
x-u u-s
Clinical assessment
Intraoperative measurement
CT assessment
4.0 (0.0–7.0) 3.5 (0.0–6.0)
4.0 (2.0–7.0) 3.0 (1.5–6.0)
2.6 (0.8–6.1) 0.0 (0.0–3.4)
Numbers are median, cm (range) x-u = halfway between the xiphoid and umbilicus whereas u-s = between the umbilicus and the symphysis.
Table 2. Muscular strength measured in Nm with the Biodex Sys-
tem 4 configured with an application for measurement of abdominal muscle strength. Mean and range are given
straps to prevent muscles other than the abdominals from being involved. These tests were performed before surgery and 12 months after surgery. A total of 57 patients performed the preoperative Biodex test and preoperative clinical and CT assessments of ARD width. ARD width, both above and below the umbilicus, was correlated with the three Biodex modalities; extension, flexion and isometric abdominal muscle force. Correlations were also tested between Biodex results and waist circumference and BMI. The study was approved by the regional ethical committee (D.nr. 2009/227–31). Statistics Statistics were performed using Statistica® version 12 (Statsoft, Tulsa, USA). Non-parametric statistics were generally used. Correlations were calculated according to the Spearman test.
Results
The median age of the 55 women and two men at surgery was 39.8 years (range 25–60 years) and the median body mass index (BMI) was 23 kg/m2 (range 18–31), waist circumference ranged between 71 and 116 cm (median 81). All women had given birth to at least one child. The width of the ARD, assessed preoperatively at the out114
Dig Surg 2015;32:112–116 DOI: 10.1159/000371859
Nm
p value
R
Flex 30° Flex 60° Ext 30° Ext 60° Isometric
83.6 (29.6–227.3) 94.2 (22.0–233.3) 96.3 (29.1–238.8) 103.5 (36.9–254.6) 66.8 (14.6–142.9)
Dig Surg 2015;32:112–116 DOI: 10.1159/000371859
Correlation between Abdominal Rectus Diastasis Width and Abdominal Muscle Strength Ulf Gunnarsson a Birgit Stark c Ursula Dahlstrand b Karin Strigård a
a
Department of Surgical and Perioperative Sciences, Umeå University, Umeå, b Department for Surgery, CLINTEC, Karolinska Institutet, Stockholm, and c Department for Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden
Abstract Background: Surgery for Abdominal Rectus Diastasis (ARD) is a controversial topic and some argue that it is solely an aesthetic problem. Many symptoms in these patients are indefinite, and no objective criteria have been established, indicating which patients are likely to benefit from surgery. This study investigated the correlation between preoperative assessment and intraoperative measurement of ARD width, and objective measurements of muscle strength. Methods: 57 patients undergoing surgery for ARD underwent preoperative assessment of ARD width by clinical measurement and CT scan, and thereafter intraoperative measurement. Abdominal muscle strength was investigated using the Biodex System 4 including flexion, extension and isometric measurements. Correlations were calculated by the Spearman test. Results: Intraoperative ARD width between the umbilicus and the symphysis correlated strongly with Biodex measurements during flexion (p = 0.007, R = –0.35) and isometric work load (p = 0.01, R = –0.34). The following measurements showed no correlation: between
© 2015 S. Karger AG, Basel 0253–4886/15/0322–0112$39.50/0 E-Mail [email protected] www.karger.com/dsu
muscle strength and BMI; muscle strength and waistline; or between muscle strength and ARD width above the umbilicus, assessed preoperatively at the outpatient clinic, by CT scan, or measured intraoperatively. Conclusion: There is a strong correlation between intraoperatively measured ARD width below the umbilicus and flexion and isometric abdominal muscle strength measured with the Biodex System 4. © 2015 S. Karger AG, Basel
Introduction
There is still controversy regarding surgery for abdominal rectus diastasis (ARD) [1]. The value of symptoms such as back pain, weak abdominal muscle strength and discomfort has not been specifically determined, and it has been questioned whether these are correlated to ARD or not. Outcome of surgery among the present patients show that several symptoms are relieved after surgery [2]. We urgently need tools that can predict functional outcome after surgery for ARD, and not just for evaluation of subjective symptoms. Such tools include validated questionnaires to measure pain before and after surgery such as the VHPQ (Ventral Hernia Pain QuesKarin Strigård Surgical Center NUS SE–907 50 Umeå (Sweden) E-Mail karin.strigard @ umu.se
Downloaded by: Stockholms Universitet 198.143.54.1 - 8/3/2015 4:35:25 PM
Key Words Rectus diastasis · ARD · Biodex System 4 · Muscle strength · Clinical symptoms
Fig. 1. Intraoperative picture of ARD. Width 4 cm below the umbilicus and 3 cm above. During dissection in top the markings for the lowest rib are visible.
In the present study, patients with symptoms from their ARD (≥3 cm above or below the umbilicus) were randomized to surgery with either a double-running suture technique (Quill) or a sublay mesh technique described in a previous paper [2]. Patients who did not fulfill inclusion criteria were not operated in the public system since this diagnosis is not seen as a disease. Inclusion time was between December 2009 and December 2012. The intended sample size was calculated on the premise that there is a clinically significant difference in one-year recurrence rate, measured with CT and/or clinically, between the two ARD surgical repair techniques, which was the primary endpoint of the background study. Functional complaints arising from the ARD were discomfort and/or painful tenderness. The abdominal outline with bulging of the lin-
ea alba are most commonly pronounced below the umbilicus in women after pregnancy [8]. Clinical assessment of the ARD as well as CT scan and Biodex System 4 muscle force measurements were performed prior to surgery. The ARD width was assessed preoperatively, using a tape measure, between the xiphoid process and the umbilicus and between the umbilicus and symphysis, in a relaxed supine position. One physician performed all measurements. The width of the diastasis in the upper and the lower midline was measured three times in each patient. The average of the three measurements was used in the analyses. The same measuring points were used when evaluating the CT scan as well as when measuring the width during surgery (fig. 1). CT scans were evaluated by two independent radiologists. The Biodex Multi-Joint System-4 Pro machine (Biodex®, Inc., Shirley, N.Y., USA) has a unit that makes it possible to test both back and abdominal muscle strength even if the individual muscle groups cannot be differentiated. Flexion, extension and isokinetic muscle strengths were measured and the results given in Newtonmeter (Nm). In the isokinetic test, there is a pre-designated maximal movement speed that cannot be exceeded. Maximal strength (peak torque) and maximal work are tested during the flexion and extension tests, 30°/s and 60°/s. In the test situation, the subject sits in a chair-like position with the hip at 90 degrees [7] (fig. 2). Anatomical landmarks are monitored to make it possible to reproduce the exact position in a retest situation. The body is secured with
Rectus Diastasis and Abdominal Muscle Strength
Dig Surg 2015;32:112–116 DOI: 10.1159/000371859
Material and Methods
113
Downloaded by: Stockholms Universitet 198.143.54.1 - 8/3/2015 4:35:25 PM
tionnaire) [3], VAS scales for self-evaluation of muscle strength [2], or the SF 36 [4]. VHPQ is a questionnaire validated for pain in the abdominal wall and its consequences in daily life. Another objective tool is the Biodex System for measurement of abdominal muscle strength, which has been validated for ARD [5] and shown to have excellent internal validity. If the symptoms from ARD emanate from a decrease in abdominal wall muscle strength, it should be possible to determine a correlation between the width of the ARD and abdominal muscle strength. As shown previously [6], the correlation between the ARD width estimated clinically using a tape measure and that estimated by CT scan is low. The intraoperative finding was regarded as the ‘true’ ARD width, and that correlated fairly well with preoperative clinical assessment using a tape measure. Using the Biodex System 4, patient muscle force is measured under flexion and extension at two different speeds as well as isometrically. In patients with ARD, flexion and isometric force results were the most reliable [5]. Extension may reflect the activation of muscles other than abdominal, and this test situation also appeared more complex for the patient to follow. In healthy volunteers, both flexion and extension testing seemed easier to perform than isometric testing. In another study evaluating patients with giant ventral hernia, isometric testing appeared to be the easiest [7]. Since different abdominal wall dysfunctions show different symptoms and problems, it is important to validate the Biodex System 4 for each specific type of abdominal wall muscle dysfunction. The purpose of this study was to investigate the relationship between preoperative assessment (clinical and CT-scan) and intraoperative ARD width measurements, and the relationship between ‘true’ ARD width and objective muscle strength using the Biodex System 4.
Table 1. ARD in cm; preoperative and intraoperative measurements with a tape and evaluation by CT scan
x-u u-s
Clinical assessment
Intraoperative measurement
CT assessment
4.0 (0.0–7.0) 3.5 (0.0–6.0)
4.0 (2.0–7.0) 3.0 (1.5–6.0)
2.6 (0.8–6.1) 0.0 (0.0–3.4)
Numbers are median, cm (range) x-u = halfway between the xiphoid and umbilicus whereas u-s = between the umbilicus and the symphysis.
Table 2. Muscular strength measured in Nm with the Biodex Sys-
tem 4 configured with an application for measurement of abdominal muscle strength. Mean and range are given
straps to prevent muscles other than the abdominals from being involved. These tests were performed before surgery and 12 months after surgery. A total of 57 patients performed the preoperative Biodex test and preoperative clinical and CT assessments of ARD width. ARD width, both above and below the umbilicus, was correlated with the three Biodex modalities; extension, flexion and isometric abdominal muscle force. Correlations were also tested between Biodex results and waist circumference and BMI. The study was approved by the regional ethical committee (D.nr. 2009/227–31). Statistics Statistics were performed using Statistica® version 12 (Statsoft, Tulsa, USA). Non-parametric statistics were generally used. Correlations were calculated according to the Spearman test.
Results
The median age of the 55 women and two men at surgery was 39.8 years (range 25–60 years) and the median body mass index (BMI) was 23 kg/m2 (range 18–31), waist circumference ranged between 71 and 116 cm (median 81). All women had given birth to at least one child. The width of the ARD, assessed preoperatively at the out114
Dig Surg 2015;32:112–116 DOI: 10.1159/000371859
Nm
p value
R
Flex 30° Flex 60° Ext 30° Ext 60° Isometric
83.6 (29.6–227.3) 94.2 (22.0–233.3) 96.3 (29.1–238.8) 103.5 (36.9–254.6) 66.8 (14.6–142.9)
