RESEARCH
Biomechanical Comparison of Different Suturing Techniques in Rabbit Medial Gastrocnemius Muscle Laceration Repair Min He, PhD,*Þ Sandeep J. Sebastin, MD,* Aaron W.T. Gan, MD,* Aymeric Y.T. Lim, MD,*Þ and Alphonsus K.S. Chong, MD*Þ Introduction: Skeletal muscle laceration is a common injury. Repair of disrupted delicate tissue is still a clinical challenge for surgeons. A few different muscle repair techniques have been reported. However, the best muscle repair technique has not been identified. The aim of the present study is to compare the biomechanical features of different repair techniques in muscles to identify the most effective one. Material and Methods: New Zealand white rabbits (2.5Y3 kg) were euthanized and medial gastrocnemius muscles were isolated. The muscles were completely transected with scalpels and then repaired by 3 different techniques, namely, (1) 2-strand mattress, (2) 4-strand Kessler (with epitendinous suture), and (3) Mason-Allen. To measure suture performance, the repaired specimens were mounted onto a mechanical testing machine Instron 5543. The muscles were loaded to failure at a constant speed of 60 mm/min. Data collected from Merlin v5.31 software were used to compute the biomechanical properties of each specimen. Results: There was no significant difference in the mean maximum load of Kessler group (15.5 N) and Mason-Allen group (13.2 N), whereas the mean maximum load of the control (Mattress) group (4.4 N) was significantly smaller than the other 2 groups. Moreover, Kessler stitches were the stiffest among the 3. It is noteworthy that the mechanisms of failure were different: Kessler stitches were all pulled out longitudinally, whereas Mason-Allen stitches transmitted load across the laceration and ruptures occur at areas adjacent to the stitches, indicating that muscle is the weakest element in the biomechanical testing. Conclusions: Both Kessler and Mason-Allen stitches have shown better biomechanical features compared with the control group. Further study has to be done to compare the effect of these 2 techniques on muscle regeneration and scar formation in an in vivo model. Key Words: muscle repair, muscle laceration, biomechanical testing (Ann Plast Surg 2014;73: 333Y335)
mobilization possible and prevent rupture at injured site, a strong suturing technique is highly desirable. A good surgical repair of lacerated/ruptured muscle tissue is difficult as the tissue is delicate and does not hold sutures well. Moreover, the retraction of muscle fibers makes the repair process more complex. The use of a tendon autograft to anchor the repair has been suggested.4 The method use of the modified Kessler suture has been recommended for the management of lacerated muscle.5 Recent study suggests that epimysium incorporation into suturing improves the competence of repairs.6 A new combination stitching technique, with a modified Mason-Allen stitch around a perimeter stitch, has shown superior features compared with the Kessler suture in pig quadriceps femoris muscle. Improved function, appearance, and patient satisfaction compared with nonoperative treatment have been shown using this combination suture technique; however, there are few published literatures on the comparison of biomechanical properties of different repair techniques.7,8 In the present study, the effect of different suturing techniques on the biomechanical features of repaired rabbit medial gastrocnemius muscle was compared.
MATERIAL AND METHODS Animals New Zealand White rabbits (weight 2.5Y3 kg) were used under the guidance of the Institutional Animal Care and Use Committee and with approval of our institutional review board. The animals were anesthetized with a combination of an intramuscular ketamine (50 mg/kg) and xylazine (10 mg/kg) and killed by an intravenous injection of a lethal dose of pentobarbitone. Medial gastrocnemius muscles were isolated.
Muscle Repair
S
Medial gastrocnemius muscles were completely and sharply transected with a scalpel at the middle position and then repaired by 3 different techniques (Fig. 1). In the first group, the muscles were
Received December 30, 2011, and accepted for publication, after revision, October 24, 2012. From the *Department of Hand and Reconstructive Microsurgery, National University Hospital, Singapore; and †Department of Orthopedic Surgery, National University of Singapore, Singapore. Conflicts of interest and sources of funding: Supported by the National Medical Research Council, Singapore (NMRC/1116/2007). Reprints: Aaron W.T. Gan, MD, Department of Hand and Reconstructive Microsurgery, National University Hospital, 1E Kent Ridge Rd, NUHS Tower Block, Level 11, Singapore 119228. E-mail: [email protected]. Copyright * 2013 by Lippincott Williams & Wilkins ISSN: 0148-7043/14/7303-0333 DOI: 10.1097/SAP.0b013e31827ae9b0
FIGURE 1. Diagram of the stitches. A, Mattress, (B) Kessler, and (C) Mason-Allen.
keletal muscle laceration and rupture are common injuries and may result in significant morbidity. However, repair of delicate muscle tissues is a challenging task. Although an injured muscle is capable of healing by initiating the regeneration of myofibers in the damaged tissue, this healing process is slow, incomplete, and hindered by the formation of scar tissue.1,2 Compared with extensive studies on tendon repair, studies on muscle repair are still very limited. Similar to what is known in tendon healing, early mobilization has shown a benefit effect on muscle healing.3 To make early
Annals of Plastic Surgery
& Volume 73, Number 3, September 2014
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Copyright © 2014 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
333
Annals of Plastic Surgery
He et al
& Volume 73, Number 3, September 2014
FIGURE 2. Diagram of the modified Mason-Allen stitches in a quarter of medial gastrocnemius muscles. A, Placement of an anchor, (B) a running interlocking stitch along the border using Prolene 6/0, and (C) the modified Mason-Allen stitches using Prolene 5/0.
repaired by 2-strand mattress stitches using 5/0 polypropylene (Prolene; Johnson & Johnson, Somerville, NJ) (sample size, n = 9); in the second group, the muscles were repaired by 4-strand Kessler stitches using 5/0 polypropylene (sample size, n = 8); and in the third group, the muscles were repaired by modified Mason-Allen stitches using 6/0 polypropylene (Prolene; Johnson & Johnson) epimysial suture and 5/0 polypropylene core suture (sample size, n = 10) (Fig. 2).7,8
FIGURE 4. Stiffness of different repair techniques. Data were expressed as the means (SD). *P G 0.05; #P G 0.01.
Statistical Analysis
maximum load in Kessler and Mason-Allen group was 15.5 and 13.2 N, respectively. Statistical analysis showed that there was significant difference between Kessler and Mattress groups and between the Mason-Allen and Mattress groups. But there was no significant difference between Kessler and Mason-Allen groups. As shown in Figure 4, the stiffness in the control (Mattress) group was 0.3 N/mm. The mean stiffness in Kessler and MasonAllen groups was 1 and 0.6 N/mm, respectively. Statistic analysis shows that there is a significant difference between Mattress and Kessler groups and between Kessler and Mason-Allen groups. These findings indicate that Kessler stitches are the stiffest among the 3. Besides the biomechanical features, the mechanism of failure in Kessler and Mason-Allen groups were also compared (Fig. 5). Kessler stitches were all pulled out longitudinally, indicating that suture portion is the weakest link. In contrast, Mason-Allen stitches can transmit load across the laceration and ruptures occur at areas adjacent to suture portion, indicating that muscle is the weakest element in the testing.
Data were expressed as the means (SD). In all figures, vertical error bars denote standard deviation. The significance of changes was evaluated by using 2-tailed t test when comparing 2 groups. A P value of G0.05 was considered to indicate a significant difference.
Both Kessler and Mason-Allen sutures have shown better biomechanical features compared with control 2-strand mattress stitches
Biomechanical Testing The repaired specimens were mounted onto a mechanical testing machine Instron 5543 (Instron, Norwood, Mass). A preload force of 2 N was applied as initial tension. The muscles were marked with black ink approximately 1 cm away from the site of laceration. These 2 markers were used to analyze the surface strain by a noncontacting video extensometer (Instron). The muscles were then loaded to failure at a constant speed of 60 mm/min. Data collected from Merlin v5.31 software (Instron) were used to calculate the biomechanical properties of each specimen. Stiffness is determined by calculating the slope of linear region of the load elongation curve of biomechanical testing.
DISCUSSION
RESULTS The mean maximum load for nonlacerated rabbit medial gastrocnemius muscles is 38.6 (2.2) N. As shown in Figure 3, the mean maximum load in the control (Mattress) group was 4.4 N. The mean
FIGURE 3. Maximum load of different repair techniques. Data were expressed as the means (SD). #P G 0.01. 334
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FIGURE 5. Mechanism of failure. The gray areas are the representative locations of muscle tear. A, Mattress (suture pullout), (B) Kessler (suture pullout), and (C) Mason-Allen (muscle tear occurs at areas adjacent to suture portion). * 2013 Lippincott Williams & Wilkins
Copyright © 2014 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
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& Volume 73, Number 3, September 2014
group. There was no significant difference between Kessler and Mason-Allen sutures in maximum load, which is different from the previous study in pig quadriceps femoris.8 In that study, the sutures were passed through the transverse cut end of muscle and the free end of the suture anchored to the testing device. This is not an accurate representation of a repaired muscle laceration as in the present study. The stiffness of the muscles repaired by Kessler stitches is the highest. The stiffness of the muscle applies to the immediate strength of the repair in resisting tensile forces that may disrupt the repair site. This may correspond to the amount of active or passive movement a given repaired muscle is able to withstand before a gap occurs which will affect healing. This, however, was not investigated in the current study. Although the complex combination of perimeter and MasonAllen stitches had superior pullout resistance compared to Kessler stitches using transected cadaver muscle bellies,9 it is noteworthy that in the present study rabbit medial gastrocnemius muscles ruptured adjacent to the stitches before pullout occurred in Mason-Allen group, indicating that adjacent muscle is the weakest component during biomechanical testing. The force distribution along muscle and stitches will affect rupture location and failure load. These findings also suggest that the size of repaired muscle may be an important factor that influences the performance of repair techniques. The muscle healing process goes through the following 3 stages: (1) muscle degeneration and inflammation, (2) muscle regeneration, and (3) scar formation.1,2,10 One main limitation of the present study
* 2013 Lippincott Williams & Wilkins
Biomechanical Features of Muscle Repair Techniques
is that the effect of different muscle repair techniques on in vivo muscle healing process was not investigated. A biomechanical testing and a morphological study of the muscle segments during the healing process in an in vivo model of muscle repair will provide more valuable insight. REFERENCES 1. Ciciliot S, Schiaffino S. Regeneration of mammalian skeletal muscle. Basic mechanisms and clinical implications. Curr Pharm Des. 2010;16:906Y914. 2. Karalaki M, Fili S, Philippou A, et al. Muscle regeneration: cellular and molecular events. In Vivo. 2009;23:779Y796. 3. Jarvinen MJ, Lehto MU. The effects of early mobilisation and immobilisation on the healing process following muscle injuries. Sports Med. 1993;15:78Y89. 4. Botte MJ, Gelberman RH, Smith DG, et al. Repair of severe muscle belly lacerations using a tendon graft. J Hand Surg Am. 1987;12:406Y412. 5. Chien SH, Chen SK, Lin SY, et al. Repair method and healing of skeletal muscle injury [in Chinese]. Gaoxiong Yi Xue Ke Xue Za Zhi. 1991;7:481Y488. 6. Kragh JF Jr, Svoboda SJ, Wenke JC, et al. The role of epimysium in suturing skeletal muscle lacerations. J Am Coll Surg. 2005;200:38Y44. 7. Kragh JF Jr, Basamania CJ. Surgical repair of acute traumatic closed transection of the biceps brachii. J Bone Joint Surg Am. 2002;84-A:992Y998. 8. Kragh JF Jr, Svoboda SJ, Wenke JC, et al. Suturing of lacerations of skeletal muscle. J Bone Joint Surg Br. 2005;87:1303Y1305. 9. Chance JR, Kragh JF Jr, Agrawal CM, et al. Pullout forces of sutures in muscle lacerations. Orthopedics. 2005;28:1187Y1190. 10. Lehto MU, Jarvinen MJ. Muscle injuries, their healing process and treatment. Ann Chir Gynaecol. 1991;80:102Y108.
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335
Biomechanical Comparison of Different Suturing Techniques in Rabbit Medial Gastrocnemius Muscle Laceration Repair Min He, PhD,*Þ Sandeep J. Sebastin, MD,* Aaron W.T. Gan, MD,* Aymeric Y.T. Lim, MD,*Þ and Alphonsus K.S. Chong, MD*Þ Introduction: Skeletal muscle laceration is a common injury. Repair of disrupted delicate tissue is still a clinical challenge for surgeons. A few different muscle repair techniques have been reported. However, the best muscle repair technique has not been identified. The aim of the present study is to compare the biomechanical features of different repair techniques in muscles to identify the most effective one. Material and Methods: New Zealand white rabbits (2.5Y3 kg) were euthanized and medial gastrocnemius muscles were isolated. The muscles were completely transected with scalpels and then repaired by 3 different techniques, namely, (1) 2-strand mattress, (2) 4-strand Kessler (with epitendinous suture), and (3) Mason-Allen. To measure suture performance, the repaired specimens were mounted onto a mechanical testing machine Instron 5543. The muscles were loaded to failure at a constant speed of 60 mm/min. Data collected from Merlin v5.31 software were used to compute the biomechanical properties of each specimen. Results: There was no significant difference in the mean maximum load of Kessler group (15.5 N) and Mason-Allen group (13.2 N), whereas the mean maximum load of the control (Mattress) group (4.4 N) was significantly smaller than the other 2 groups. Moreover, Kessler stitches were the stiffest among the 3. It is noteworthy that the mechanisms of failure were different: Kessler stitches were all pulled out longitudinally, whereas Mason-Allen stitches transmitted load across the laceration and ruptures occur at areas adjacent to the stitches, indicating that muscle is the weakest element in the biomechanical testing. Conclusions: Both Kessler and Mason-Allen stitches have shown better biomechanical features compared with the control group. Further study has to be done to compare the effect of these 2 techniques on muscle regeneration and scar formation in an in vivo model. Key Words: muscle repair, muscle laceration, biomechanical testing (Ann Plast Surg 2014;73: 333Y335)
mobilization possible and prevent rupture at injured site, a strong suturing technique is highly desirable. A good surgical repair of lacerated/ruptured muscle tissue is difficult as the tissue is delicate and does not hold sutures well. Moreover, the retraction of muscle fibers makes the repair process more complex. The use of a tendon autograft to anchor the repair has been suggested.4 The method use of the modified Kessler suture has been recommended for the management of lacerated muscle.5 Recent study suggests that epimysium incorporation into suturing improves the competence of repairs.6 A new combination stitching technique, with a modified Mason-Allen stitch around a perimeter stitch, has shown superior features compared with the Kessler suture in pig quadriceps femoris muscle. Improved function, appearance, and patient satisfaction compared with nonoperative treatment have been shown using this combination suture technique; however, there are few published literatures on the comparison of biomechanical properties of different repair techniques.7,8 In the present study, the effect of different suturing techniques on the biomechanical features of repaired rabbit medial gastrocnemius muscle was compared.
MATERIAL AND METHODS Animals New Zealand White rabbits (weight 2.5Y3 kg) were used under the guidance of the Institutional Animal Care and Use Committee and with approval of our institutional review board. The animals were anesthetized with a combination of an intramuscular ketamine (50 mg/kg) and xylazine (10 mg/kg) and killed by an intravenous injection of a lethal dose of pentobarbitone. Medial gastrocnemius muscles were isolated.
Muscle Repair
S
Medial gastrocnemius muscles were completely and sharply transected with a scalpel at the middle position and then repaired by 3 different techniques (Fig. 1). In the first group, the muscles were
Received December 30, 2011, and accepted for publication, after revision, October 24, 2012. From the *Department of Hand and Reconstructive Microsurgery, National University Hospital, Singapore; and †Department of Orthopedic Surgery, National University of Singapore, Singapore. Conflicts of interest and sources of funding: Supported by the National Medical Research Council, Singapore (NMRC/1116/2007). Reprints: Aaron W.T. Gan, MD, Department of Hand and Reconstructive Microsurgery, National University Hospital, 1E Kent Ridge Rd, NUHS Tower Block, Level 11, Singapore 119228. E-mail: [email protected]. Copyright * 2013 by Lippincott Williams & Wilkins ISSN: 0148-7043/14/7303-0333 DOI: 10.1097/SAP.0b013e31827ae9b0
FIGURE 1. Diagram of the stitches. A, Mattress, (B) Kessler, and (C) Mason-Allen.
keletal muscle laceration and rupture are common injuries and may result in significant morbidity. However, repair of delicate muscle tissues is a challenging task. Although an injured muscle is capable of healing by initiating the regeneration of myofibers in the damaged tissue, this healing process is slow, incomplete, and hindered by the formation of scar tissue.1,2 Compared with extensive studies on tendon repair, studies on muscle repair are still very limited. Similar to what is known in tendon healing, early mobilization has shown a benefit effect on muscle healing.3 To make early
Annals of Plastic Surgery
& Volume 73, Number 3, September 2014
www.annalsplasticsurgery.com
Copyright © 2014 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
333
Annals of Plastic Surgery
He et al
& Volume 73, Number 3, September 2014
FIGURE 2. Diagram of the modified Mason-Allen stitches in a quarter of medial gastrocnemius muscles. A, Placement of an anchor, (B) a running interlocking stitch along the border using Prolene 6/0, and (C) the modified Mason-Allen stitches using Prolene 5/0.
repaired by 2-strand mattress stitches using 5/0 polypropylene (Prolene; Johnson & Johnson, Somerville, NJ) (sample size, n = 9); in the second group, the muscles were repaired by 4-strand Kessler stitches using 5/0 polypropylene (sample size, n = 8); and in the third group, the muscles were repaired by modified Mason-Allen stitches using 6/0 polypropylene (Prolene; Johnson & Johnson) epimysial suture and 5/0 polypropylene core suture (sample size, n = 10) (Fig. 2).7,8
FIGURE 4. Stiffness of different repair techniques. Data were expressed as the means (SD). *P G 0.05; #P G 0.01.
Statistical Analysis
maximum load in Kessler and Mason-Allen group was 15.5 and 13.2 N, respectively. Statistical analysis showed that there was significant difference between Kessler and Mattress groups and between the Mason-Allen and Mattress groups. But there was no significant difference between Kessler and Mason-Allen groups. As shown in Figure 4, the stiffness in the control (Mattress) group was 0.3 N/mm. The mean stiffness in Kessler and MasonAllen groups was 1 and 0.6 N/mm, respectively. Statistic analysis shows that there is a significant difference between Mattress and Kessler groups and between Kessler and Mason-Allen groups. These findings indicate that Kessler stitches are the stiffest among the 3. Besides the biomechanical features, the mechanism of failure in Kessler and Mason-Allen groups were also compared (Fig. 5). Kessler stitches were all pulled out longitudinally, indicating that suture portion is the weakest link. In contrast, Mason-Allen stitches can transmit load across the laceration and ruptures occur at areas adjacent to suture portion, indicating that muscle is the weakest element in the testing.
Data were expressed as the means (SD). In all figures, vertical error bars denote standard deviation. The significance of changes was evaluated by using 2-tailed t test when comparing 2 groups. A P value of G0.05 was considered to indicate a significant difference.
Both Kessler and Mason-Allen sutures have shown better biomechanical features compared with control 2-strand mattress stitches
Biomechanical Testing The repaired specimens were mounted onto a mechanical testing machine Instron 5543 (Instron, Norwood, Mass). A preload force of 2 N was applied as initial tension. The muscles were marked with black ink approximately 1 cm away from the site of laceration. These 2 markers were used to analyze the surface strain by a noncontacting video extensometer (Instron). The muscles were then loaded to failure at a constant speed of 60 mm/min. Data collected from Merlin v5.31 software (Instron) were used to calculate the biomechanical properties of each specimen. Stiffness is determined by calculating the slope of linear region of the load elongation curve of biomechanical testing.
DISCUSSION
RESULTS The mean maximum load for nonlacerated rabbit medial gastrocnemius muscles is 38.6 (2.2) N. As shown in Figure 3, the mean maximum load in the control (Mattress) group was 4.4 N. The mean
FIGURE 3. Maximum load of different repair techniques. Data were expressed as the means (SD). #P G 0.01. 334
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FIGURE 5. Mechanism of failure. The gray areas are the representative locations of muscle tear. A, Mattress (suture pullout), (B) Kessler (suture pullout), and (C) Mason-Allen (muscle tear occurs at areas adjacent to suture portion). * 2013 Lippincott Williams & Wilkins
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Annals of Plastic Surgery
& Volume 73, Number 3, September 2014
group. There was no significant difference between Kessler and Mason-Allen sutures in maximum load, which is different from the previous study in pig quadriceps femoris.8 In that study, the sutures were passed through the transverse cut end of muscle and the free end of the suture anchored to the testing device. This is not an accurate representation of a repaired muscle laceration as in the present study. The stiffness of the muscles repaired by Kessler stitches is the highest. The stiffness of the muscle applies to the immediate strength of the repair in resisting tensile forces that may disrupt the repair site. This may correspond to the amount of active or passive movement a given repaired muscle is able to withstand before a gap occurs which will affect healing. This, however, was not investigated in the current study. Although the complex combination of perimeter and MasonAllen stitches had superior pullout resistance compared to Kessler stitches using transected cadaver muscle bellies,9 it is noteworthy that in the present study rabbit medial gastrocnemius muscles ruptured adjacent to the stitches before pullout occurred in Mason-Allen group, indicating that adjacent muscle is the weakest component during biomechanical testing. The force distribution along muscle and stitches will affect rupture location and failure load. These findings also suggest that the size of repaired muscle may be an important factor that influences the performance of repair techniques. The muscle healing process goes through the following 3 stages: (1) muscle degeneration and inflammation, (2) muscle regeneration, and (3) scar formation.1,2,10 One main limitation of the present study
* 2013 Lippincott Williams & Wilkins
Biomechanical Features of Muscle Repair Techniques
is that the effect of different muscle repair techniques on in vivo muscle healing process was not investigated. A biomechanical testing and a morphological study of the muscle segments during the healing process in an in vivo model of muscle repair will provide more valuable insight. REFERENCES 1. Ciciliot S, Schiaffino S. Regeneration of mammalian skeletal muscle. Basic mechanisms and clinical implications. Curr Pharm Des. 2010;16:906Y914. 2. Karalaki M, Fili S, Philippou A, et al. Muscle regeneration: cellular and molecular events. In Vivo. 2009;23:779Y796. 3. Jarvinen MJ, Lehto MU. The effects of early mobilisation and immobilisation on the healing process following muscle injuries. Sports Med. 1993;15:78Y89. 4. Botte MJ, Gelberman RH, Smith DG, et al. Repair of severe muscle belly lacerations using a tendon graft. J Hand Surg Am. 1987;12:406Y412. 5. Chien SH, Chen SK, Lin SY, et al. Repair method and healing of skeletal muscle injury [in Chinese]. Gaoxiong Yi Xue Ke Xue Za Zhi. 1991;7:481Y488. 6. Kragh JF Jr, Svoboda SJ, Wenke JC, et al. The role of epimysium in suturing skeletal muscle lacerations. J Am Coll Surg. 2005;200:38Y44. 7. Kragh JF Jr, Basamania CJ. Surgical repair of acute traumatic closed transection of the biceps brachii. J Bone Joint Surg Am. 2002;84-A:992Y998. 8. Kragh JF Jr, Svoboda SJ, Wenke JC, et al. Suturing of lacerations of skeletal muscle. J Bone Joint Surg Br. 2005;87:1303Y1305. 9. Chance JR, Kragh JF Jr, Agrawal CM, et al. Pullout forces of sutures in muscle lacerations. Orthopedics. 2005;28:1187Y1190. 10. Lehto MU, Jarvinen MJ. Muscle injuries, their healing process and treatment. Ann Chir Gynaecol. 1991;80:102Y108.
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Copyright © 2014 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
335
