2144 C OPYRIGHT Ó 2013
BY
T HE J OURNAL
OF
B ONE
AND J OINT
S URGERY, I NCORPORATED
Current Concepts Review
Peripheral Nerve Repair and Reconstruction Justin W. Griffin, MD, MaCalus V. Hogan, MD, A. Bobby Chhabra, MD, and D. Nicole Deal, MD Investigation performed at the Department of Orthopaedic Surgery, University of Virginia Health System, Charlottesville, Virginia
ä
When possible, direct repair remains the current standard of care for the repair of peripheral nerve lacerations.
ä
In large nerve gaps, in which direct repair is not possible, grafting remains the most viable option.
ä
Nerve scaffolds include autologous conduits, artificial nonbioabsorbable conduits, and bioabsorbable conduits and are options for repair of digital nerve gaps that are 2.5 cm at the site of injury will commonly necessitate nerve grafting. Tension-free suture repair remains the preferred treatment option for nerve injury. If this is not possible because of either gap formation or poor quality of tissue for repair, alternative methods should be utilized30. Simple direct repair entails suturing the nerve together in a tension-free fashion (Fig. 2). End-to-side repair may be favorable when the proximal aspect of the injured nerve is not salvageable. The distal portion of the injured nerve can be sutured to an adjacent nerve with subsequent collateral sprouting31. Yu et al. evaluated end-to-side neurorrhaphy in the ulnar nerve as the donor and in the musculocutaneous nerve as the recipient and noted collateral sprouting of intact axons of the ulnar nerve with limited functional reinnervation32. The development of novel microsurgical techniques and instrumentation led some to promote grouped fascicular repair.
This technique is similar to epineural repair, but in addition the perineural sheaths of individual fascicles are repaired under microscopic magnification. This approach attempts more accurate approximation of regenerating axons but requires more dissection and potential soft-tissue disruption. In nerves with defined motor and sensory topography, such as median or ulnar nerves in the forearm and the sciatic nerve in the thigh, such repair is often used11. With both epineural and fascicular repair, most surgeons advocate the use of 8-0 or 9-0 monofilament suture in adult patients. Direct muscular neurotization involves placing the proximal nerve stump into the muscle belly. This technique is not preferred as functional recovery is weakest with this treatment, but it remains an option when direct repair and/or reconstruction are not possible27. Fibrin glue can be considered as an adjunct or alternative to epineurial repair and is viewed by many as quick and easy to use33,34. Multiple studies have shown that fibrin glue is equivalent to suture repair and may improve resistance to gapping34. Use of Conduits A tensionless repair has been cited as one major factor to the successful recovery of sensorimotor function35. When tensionless direct repair cannot be achieved, interposed autologous nerve grafting is the gold standard for segmental defects27,36. However, autologous grafting carries with it donor-site morbidity, requirement for two anastomotic sites, increased operative time, and elevated costs, thereby justifying the ongoing search for options37. Potential advantages of nerve conduits include absorbability, lack of donor-site morbidity, and lack of axonal escape.
Fig. 2
Photograph showing a median nerve laceration in forearm repaired by direct end-to-end repair.
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TABLE I Options for Bridging Nerve Gaps Nerve Autografts Allografts Biological conduits Vein Artery Synthetic conduits Collagen Polyglycolic acid Caprolactone
Nerve scaffolds include autologous grafts, artificial nonbioabsorbable conduits, and bioabsorbable conduits (Table I). Three main types of bioabsorbable conduits are currently approved by the U.S. Food and Drug Administration (FDA) for use. With variations in tubes currently available, it is helpful to review the evidence surrounding the selection of tubes. Most regard the upper limit of nerve conduit length to be 3 cm38. In a rabbit peroneal nerve study, Strauch et al. compared results of using vein conduits from 1 to 6 cm with deteriorating results at a length of >3 cm39. Autogenous Conduits Veins are the most common type of autogenous conduit used for reconstruction of nerve defects, and are often referred to as autogenous or autologous vein nerve conduits. Chiu and Strauch conducted a prospective study of twenty-two patients with defects of £3 cm, finding that autogenous vein nerve conduits produced results as good as those of sural nerve digital grafts40. Rinker and Liau41 in their recently published prospective
randomized study compared autogenous vein nerve conduits with synthetic polyglycolic acid conduits for digital nerve gaps of 4 to 25 mm. Forty-two patients with seventy-six repairs were enrolled in the study, with thirty-seven patients with sixty-eight repairs undergoing repair with either polyglycolic acid conduits or autogenous vein nerve conduits (thirty-six with synthetic polyglycolic acid, and thirty-two with vein conduits). The authors analyzed sensory recovery at six and twelve months after repair, the time and cost of repair, and the complication profile between the two treatment groups and found equivalent results with similar cost profiles and sensory recovery outcomes41. Collagen Conduits Type-I collagen and Type-IV collagen remain the most commonly used nerve conduit design, with Type-I collagen being most biocompatible42. Figure 3 demonstrates a commonly available collagen conduit used to bridge a nerve laceration. Animal studies with collagen conduits have demonstrated equivalent efficacy when compared with autograft; however, clinical studies are lacking43,44. To date, only case series have been published with no documented Level-I studies available. Bushnell et al.43 reported a Level-IV case series of twelve digital nerve gaps from 10 to 12 mm over a two-year period. Outcomes in this study were measured with use of American Society for Surgery of the Hand (ASSH) guidelines with static 2-point discrimination, Disabilities of the Arm, Shoulder and Hand (DASH) scores, and Semmes-Weinstein testing. In their study of twelve patients, three of whom were excluded, of the remaining nine patients, four (44%) had excellent results, four (44%) had good results, and one (11%) had fair results with an average DASH score of 10 points. Five patients had full sensory recovery, two patients had diminished sensory recovery, one patient had diminished protective sensation, and one patient had loss of sensation. Lohmeyer et al.45 performed a prospective cohort study with collagen conduits to repair twelve digital
Fig. 3
Photograph showing a collagen conduit used to bridge traumatic nerve laceration.
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nerves with an average 12.7-mm gap. At the one-year followup, of the twelve patients, four (33%) had excellent sensory recovery, five (42%) had good sensory recovery, one (8%) exhibited poor sensory recovery, and two (17%) had no sensory recovery. However, grading of outcomes using 2-point discrimination remains nonstandardized and no studies have examined motor recovery with collagen tubes42. Polyglycolic Acid Conduits The polyglycolic acid conduit is regarded as more flexible, and the porous nature allows oxygen to diffuse in and aid in regeneration with conduit resorption occurring in six months42. In a prospective case series of fifteen patients undergoing secondary nerve reconstructions of digital nerve gaps measuring approximately 17 mm with polyglycolic acid tubes, Mackinnon and Dellon 46 found that five patients (33%) had excellent sensory recovery, eight patients (53%) had good recovery, and two patients (14%) had poor or no recovery. Sensory data were gathered with use of the British Medical Research Council sensory nerve grading scale with moving and static 2-point discrimination. Although that study was an early Level-IV study, Mackinnon and Dellon concluded that polyglycolic acid tubes could produce results equivalent to the classic nerve graft without donor-site morbidity with gaps up to 3 cm. In a cohort study, Battiston et al.47 examined the utility of polyglycolic acid tubes compared with biologically constructed muscle-vein conduits reporting equivalent results. Thirty patients were treated for digital nerve injuries. Of these patients, muscle-vein combined conduits were used in thirteen patients and polyglycolic acid conduits were used in seventeen patients. The authors compared outcomes with use of the MackinnonDellon modification of the British Medical Research Council scale. Results showed no notable differences between the two groups with respect to evaluation testing used, although the polyglycolic acid group achieved S4 sensation (excellent sensibility) in 12% (two of seventeen) compared with 38% (five of thirteen) of the vein conduit group. The evidence must be weighed with the fact that certain patients underwent immediate repair while others were delayed. Weber et al.48 compared polyglycolic acid conduits with primary repair or autograft for digital nerve injuries in a LevelII study. Ninety-eight patients with 136 digital nerve repairs were prospectively randomized to either a group undergoing direct end-to-end repair or utilizing a nerve graft or a group undergoing repair with a polyglycolic acid conduit. The authors reported that conduits were superior in gaps of £4 mm or >8 mm. That study provided evidence that polyglycolic acid nerve conduits produce equivalent results to nerve repairs or autologous grafts for short or moderate digital nerve gaps. Caprolactone Conduits Poly(DL-lactide-e-caprolactone) was first demonstrated in rat models to bridge 10-mm sciatic nerve gaps; these guides were reported to degrade completely in one year. Poly(DL-lactide-ecaprolactone) is another bioabsorbable conduit that may be used to bridge nerve gaps49. Bertleff et al.50 performed a multicenter,
blinded, randomized controlled trial of thirty patients with thirty-four nerve injuries using caprolactone Neurolac nerve tubes (Polyganics, Groningen, the Netherlands) compared with primary repair for digital nerve lacerations in gaps of 6 to 8 mm. Moving and static 2-point discrimination was 7 to 10 mm for both the experimental and control groups38. Relative indications for nerve tubes based on the above studies include nerve gaps of
BY
T HE J OURNAL
OF
B ONE
AND J OINT
S URGERY, I NCORPORATED
Current Concepts Review
Peripheral Nerve Repair and Reconstruction Justin W. Griffin, MD, MaCalus V. Hogan, MD, A. Bobby Chhabra, MD, and D. Nicole Deal, MD Investigation performed at the Department of Orthopaedic Surgery, University of Virginia Health System, Charlottesville, Virginia
ä
When possible, direct repair remains the current standard of care for the repair of peripheral nerve lacerations.
ä
In large nerve gaps, in which direct repair is not possible, grafting remains the most viable option.
ä
Nerve scaffolds include autologous conduits, artificial nonbioabsorbable conduits, and bioabsorbable conduits and are options for repair of digital nerve gaps that are 2.5 cm at the site of injury will commonly necessitate nerve grafting. Tension-free suture repair remains the preferred treatment option for nerve injury. If this is not possible because of either gap formation or poor quality of tissue for repair, alternative methods should be utilized30. Simple direct repair entails suturing the nerve together in a tension-free fashion (Fig. 2). End-to-side repair may be favorable when the proximal aspect of the injured nerve is not salvageable. The distal portion of the injured nerve can be sutured to an adjacent nerve with subsequent collateral sprouting31. Yu et al. evaluated end-to-side neurorrhaphy in the ulnar nerve as the donor and in the musculocutaneous nerve as the recipient and noted collateral sprouting of intact axons of the ulnar nerve with limited functional reinnervation32. The development of novel microsurgical techniques and instrumentation led some to promote grouped fascicular repair.
This technique is similar to epineural repair, but in addition the perineural sheaths of individual fascicles are repaired under microscopic magnification. This approach attempts more accurate approximation of regenerating axons but requires more dissection and potential soft-tissue disruption. In nerves with defined motor and sensory topography, such as median or ulnar nerves in the forearm and the sciatic nerve in the thigh, such repair is often used11. With both epineural and fascicular repair, most surgeons advocate the use of 8-0 or 9-0 monofilament suture in adult patients. Direct muscular neurotization involves placing the proximal nerve stump into the muscle belly. This technique is not preferred as functional recovery is weakest with this treatment, but it remains an option when direct repair and/or reconstruction are not possible27. Fibrin glue can be considered as an adjunct or alternative to epineurial repair and is viewed by many as quick and easy to use33,34. Multiple studies have shown that fibrin glue is equivalent to suture repair and may improve resistance to gapping34. Use of Conduits A tensionless repair has been cited as one major factor to the successful recovery of sensorimotor function35. When tensionless direct repair cannot be achieved, interposed autologous nerve grafting is the gold standard for segmental defects27,36. However, autologous grafting carries with it donor-site morbidity, requirement for two anastomotic sites, increased operative time, and elevated costs, thereby justifying the ongoing search for options37. Potential advantages of nerve conduits include absorbability, lack of donor-site morbidity, and lack of axonal escape.
Fig. 2
Photograph showing a median nerve laceration in forearm repaired by direct end-to-end repair.
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TABLE I Options for Bridging Nerve Gaps Nerve Autografts Allografts Biological conduits Vein Artery Synthetic conduits Collagen Polyglycolic acid Caprolactone
Nerve scaffolds include autologous grafts, artificial nonbioabsorbable conduits, and bioabsorbable conduits (Table I). Three main types of bioabsorbable conduits are currently approved by the U.S. Food and Drug Administration (FDA) for use. With variations in tubes currently available, it is helpful to review the evidence surrounding the selection of tubes. Most regard the upper limit of nerve conduit length to be 3 cm38. In a rabbit peroneal nerve study, Strauch et al. compared results of using vein conduits from 1 to 6 cm with deteriorating results at a length of >3 cm39. Autogenous Conduits Veins are the most common type of autogenous conduit used for reconstruction of nerve defects, and are often referred to as autogenous or autologous vein nerve conduits. Chiu and Strauch conducted a prospective study of twenty-two patients with defects of £3 cm, finding that autogenous vein nerve conduits produced results as good as those of sural nerve digital grafts40. Rinker and Liau41 in their recently published prospective
randomized study compared autogenous vein nerve conduits with synthetic polyglycolic acid conduits for digital nerve gaps of 4 to 25 mm. Forty-two patients with seventy-six repairs were enrolled in the study, with thirty-seven patients with sixty-eight repairs undergoing repair with either polyglycolic acid conduits or autogenous vein nerve conduits (thirty-six with synthetic polyglycolic acid, and thirty-two with vein conduits). The authors analyzed sensory recovery at six and twelve months after repair, the time and cost of repair, and the complication profile between the two treatment groups and found equivalent results with similar cost profiles and sensory recovery outcomes41. Collagen Conduits Type-I collagen and Type-IV collagen remain the most commonly used nerve conduit design, with Type-I collagen being most biocompatible42. Figure 3 demonstrates a commonly available collagen conduit used to bridge a nerve laceration. Animal studies with collagen conduits have demonstrated equivalent efficacy when compared with autograft; however, clinical studies are lacking43,44. To date, only case series have been published with no documented Level-I studies available. Bushnell et al.43 reported a Level-IV case series of twelve digital nerve gaps from 10 to 12 mm over a two-year period. Outcomes in this study were measured with use of American Society for Surgery of the Hand (ASSH) guidelines with static 2-point discrimination, Disabilities of the Arm, Shoulder and Hand (DASH) scores, and Semmes-Weinstein testing. In their study of twelve patients, three of whom were excluded, of the remaining nine patients, four (44%) had excellent results, four (44%) had good results, and one (11%) had fair results with an average DASH score of 10 points. Five patients had full sensory recovery, two patients had diminished sensory recovery, one patient had diminished protective sensation, and one patient had loss of sensation. Lohmeyer et al.45 performed a prospective cohort study with collagen conduits to repair twelve digital
Fig. 3
Photograph showing a collagen conduit used to bridge traumatic nerve laceration.
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nerves with an average 12.7-mm gap. At the one-year followup, of the twelve patients, four (33%) had excellent sensory recovery, five (42%) had good sensory recovery, one (8%) exhibited poor sensory recovery, and two (17%) had no sensory recovery. However, grading of outcomes using 2-point discrimination remains nonstandardized and no studies have examined motor recovery with collagen tubes42. Polyglycolic Acid Conduits The polyglycolic acid conduit is regarded as more flexible, and the porous nature allows oxygen to diffuse in and aid in regeneration with conduit resorption occurring in six months42. In a prospective case series of fifteen patients undergoing secondary nerve reconstructions of digital nerve gaps measuring approximately 17 mm with polyglycolic acid tubes, Mackinnon and Dellon 46 found that five patients (33%) had excellent sensory recovery, eight patients (53%) had good recovery, and two patients (14%) had poor or no recovery. Sensory data were gathered with use of the British Medical Research Council sensory nerve grading scale with moving and static 2-point discrimination. Although that study was an early Level-IV study, Mackinnon and Dellon concluded that polyglycolic acid tubes could produce results equivalent to the classic nerve graft without donor-site morbidity with gaps up to 3 cm. In a cohort study, Battiston et al.47 examined the utility of polyglycolic acid tubes compared with biologically constructed muscle-vein conduits reporting equivalent results. Thirty patients were treated for digital nerve injuries. Of these patients, muscle-vein combined conduits were used in thirteen patients and polyglycolic acid conduits were used in seventeen patients. The authors compared outcomes with use of the MackinnonDellon modification of the British Medical Research Council scale. Results showed no notable differences between the two groups with respect to evaluation testing used, although the polyglycolic acid group achieved S4 sensation (excellent sensibility) in 12% (two of seventeen) compared with 38% (five of thirteen) of the vein conduit group. The evidence must be weighed with the fact that certain patients underwent immediate repair while others were delayed. Weber et al.48 compared polyglycolic acid conduits with primary repair or autograft for digital nerve injuries in a LevelII study. Ninety-eight patients with 136 digital nerve repairs were prospectively randomized to either a group undergoing direct end-to-end repair or utilizing a nerve graft or a group undergoing repair with a polyglycolic acid conduit. The authors reported that conduits were superior in gaps of £4 mm or >8 mm. That study provided evidence that polyglycolic acid nerve conduits produce equivalent results to nerve repairs or autologous grafts for short or moderate digital nerve gaps. Caprolactone Conduits Poly(DL-lactide-e-caprolactone) was first demonstrated in rat models to bridge 10-mm sciatic nerve gaps; these guides were reported to degrade completely in one year. Poly(DL-lactide-ecaprolactone) is another bioabsorbable conduit that may be used to bridge nerve gaps49. Bertleff et al.50 performed a multicenter,
blinded, randomized controlled trial of thirty patients with thirty-four nerve injuries using caprolactone Neurolac nerve tubes (Polyganics, Groningen, the Netherlands) compared with primary repair for digital nerve lacerations in gaps of 6 to 8 mm. Moving and static 2-point discrimination was 7 to 10 mm for both the experimental and control groups38. Relative indications for nerve tubes based on the above studies include nerve gaps of
