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The AO 8 mm solid tibial nail is not defunct
Injury, Int. J. Care Injured (2007) 38, 1300—1304
www.elsevier.com/locate/injury
The AO 8 mm solid tibial nail is not defunct K. Sehat *, A. Aladin, D. Calthorpe Derbyshire Royal Infirmary, London Road, Derby DE1 2QY, UK Accepted 15 May 2006
KEYWORDS Unreamed tibial nail (UTN); AO tibial nail; Tibial fracture; Intramedullary nailing; Reaming; Non-reamed
Summary The AO 8 mm unreamed tibial nail (UTN) is an established implant that has in some publications been associated with high rate of distal locking screw breakage and failure. Larger reamed nails are now increasingly favoured. We have used the 8 mm UTN employing all three available distal screws when appropriate and with a restricted initial weight-bearing regimen. Our experience has been satisfactory with 95% union rate and no adverse effect of distal locking screw breakage. This slender nail requires less frequent reaming which may be an advantage in at least some situations. We suggest that it should be considered an alternative to larger reamed nails and can perform satisfactorily with appropriate application. # 2007 Elsevier Ltd. All rights reserved.
Introduction The management of the fractured tibia, despite its frequent occurrence remains the subject of debate. In the senior author’s institution, for several years, the senior author’s preference and the most commonly used device has been the AO solid 8 mm unreamed tibial intramedullary nail (AO UTN). It uses two proximal and three distal locking screws. The small diameter of the nail necessitates relatively small diameter 3.9 mm locking screws. In our experience it had produced satisfactory results but it came to our attention that preference is now given in the literature and in common practice to larger diameter reamed nails. One study has even
recommended against the use of the 8 mm UTN.4 On the other hand, attention is now also paid to the adverse systemic inflammatory effects of trauma and surgery for trauma, notably the reaming of long bones. Another concern is the risk of thermal osteonecrosis caused by exuberant reaming. We felt that the poor results reported4 for the UTN may have been related to the method by which it was employed, in particular relating to the number of distal locking screws and the weight-bearing regimen. However, given the reported failure rate, we have reviewed our own results with the UTN and found them to be satisfactory.
Patients and method * Corresponding author at: 18 Covent Gardens, Nottingham NG12 2NF, UK. Tel.: +44 7946 471546. E-mail address: [email protected] (K. Sehat).
The hospital trauma theatre logbook was examined and 80 consecutive patients identified who had been
0020–1383/$ — see front matter # 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.injury.2006.05.024
The AO 8 mm solid tibial nail is not defunct
1301
treated with this device from 1997 to 2002. Hospital case notes and radiographs were studied. Closed and open fractures were all included. All fractures were displaced and unstable, requiring internal fixation and one case involved prophylactic nailing for a malignant lytic lesion. Some patients will have a very narrow medullary canal and require reaming even to accommodate an 8 mm nail, however, using this slender nail minimises the amount of reaming that is required. Our practice is to use two distal locking screws with mid-shaft fractures if a tight interference fit has been obtained. Otherwise, and with distal shaft and metaphyseal fractures, three distal locking screws are used (Fig. 1). Patients are mobilised non-weight bearing initially and followed up in the outpatient clinic. Full weight bearing is permitted when radiological signs of early union appear. This, practice is in accordance with the manufacturers instructions.
Results Of 80 patients, 55 were male and 25 were female. The mean age was 43 years. Fifteen patients were noted to have an osteopenic plain radiograph appearance. One patient with a malignant lytic lesion had a prophylactic nailing. Seventy-five fractures involved the shaft (AO type 42) and four fractures the metaphysis (AO type 43) supplemented with percutaneous screws (Fig. 2). The AO classifications of the fractures are shown in Table 1. In 71 cases the fibula was also fractured. The lead surgeon was a consultant in 36 cases, a trainee with appropriate supervision in 39 cases and joint consultant and trainee in five cases. Minimal reaming was required to accommodate the 8 mm nail in 10 cases with very narrow medullary canals. Sixty-six cases were unreamed whilst in the remaining four cases, the operation note was unclear on whether or not reaming had been employed. In accordance with our practice, 28 cases had required three distal locking screws and 49 cases two screws. (In one case only one screw had been used.) In seven cases distal locking screws broke only at a late stage and no adverse event was related to these. Dynamisation was performed in 20 cases and in three of those by removing distal locking screws (in cases with inadequate space proximally for nail protrusion following dynamisation). A further five patients requested removal of distal screws that were symptomatic, following union. Six patients were lost to follow up as they left the area and one patient died of an unrelated cause.
Figure 1 Three distal locking screws with fracture with distal extension.
Complications included one nail that was too long and was revised the next day, and one broken nail in a non-compliant, morbidly obese diabetic patient with an insensate foot who unfortunately sustained a further fall and fractured the nail. Three distal locking screws had been used and these remained intact. This was revised to a larger reamed nail and united. Two further nails were also revised due to non-union. With these four cases failing to unite, the union rate was 95% in the 73 patients followed up. Radiographic union was defined as cortical continuity on AP and lateral views in keeping with the definition used in a significant previous study of this
1302
K. Sehat et al.
Figure 2
Nail supplemented with percutaneous screw fixation of distal extension into ankle joint.
implant.4 Radiographic union occurred at a mean of 19 weeks (range 6—49 weeks). The mean interval to permission to full weight bearing (when callus was seen or at discretion of clinician) was 12 weeks
(range 0—23 weeks). Patients with transverse fractures had been allowed full weight bearing even in the absence of callus at 6 weeks or earlier with no adverse consequence.
The AO 8 mm solid tibial nail is not defunct
1303
Table 1 AO classification of fractures and their frequency AO classification
Frequency
42A1 42A2 42A3 42B1 42B2 42B3 42C1 42C2 42C3 43A1 43C1 43C2 Others
18 15 12 9 4 3 4 3 3 1 2 1 5
Discussion In support of our findings, a study by Gregory and Sanders6 in 1995 reported satisfactory results with the use of the AO unreamed tibial nail. The mean time to union was 16 weeks. No broken nails occurred in their series and only one complication arising from locking screw breakage was seen (in a non-compliant patient). Melcher et al.10 reported their use of the AO UTN with satisfactory results and although they observed distal locking screw breakages, given that their weight-bearing regimen was in a controlled manner, they did not experience any complication related to screw breakage. Similarly, Angliss et al.1 noted that distal locking screw breakage could be avoided by restriction of weight bearing in the first 6 weeks. The fact that the number of locking screws is important is highlighted by a study by Kneifel and Buckley8 who compared the performance of one versus two locking screws in tibial nails and found that one screw fails significantly more commonly than two screws (Fig. 3). Pape et al.11 have reported deterioration in pulmonary function with reaming of the femur. They suggest that an unreamed nail may be more suitable for predisposed patients with concomitant pulmonary trauma. Studies measuring rises in inflammatory mediators with major trauma followed by surgical stabilisation have recorded a ‘‘second hit’’ with the surgery. This is associated with an increased incidence of systemic complications and a worse prognosis.5 Bone blood supply is also affected by reaming.3 There is therefore some evidence for avoiding reaming if possible. Our experience with the AO 8 mm UTN suggests that if the device is used to its optimal advantage with three distal locking screws when needed, it achieves a satisfactory union rate; comparable with
Figure 3 Inconsequential distal locking screw breakage if only two screws are used. (Weight bearing commenced after callus formation.)
other types of tibial intramedullary nails. The previously reported series4 comparing this nail with a larger reamed device found a high failure rate associated with a higher early distal locking screw breakage rate with the UTN. Given our findings, this discrepancy may be attributable to the number of distal locking screws used and also the weight-bearing regimen. The use of the available third distal screw would be expected to decrease locking screw breakage rate and hence overall nail failure rate. Limiting weight bearing in the initial post-op period may be seen as a disadvantage and it is also possible that we have been too cautious in this respect. Time to union is also quicker with earlier weight bearing in other studies.2,4,7 However, we would suggest that using a slender unreamed tibial nail, three distal locking screws when needed and non-weight bearing in the initial post-op period is an alternative approach to the use of larger reamed nails
1304 with immediate full weight bearing. The union rates are comparable. Thus the 8 mm UTN remains a satisfactory option in the treatment of tibial fractures and largely avoids the need for reaming. This technique has also been advocated for the treatment of tibial shaft fractures with severe soft tissue injury and shown to be superior to external fixation.9,12 We note the literature supporting the use of reaming as a means of improving union rate and time to union.2,4,7 However, it is not clear from the current literature whether the improved performance of the reamed nails are attributable to the effect of reaming per se or the fact that reaming allows a larger nail to be implanted with a lower hardware failure rate in those series and hence a better ‘mean’ time to union in the series. We feel this question is worthy of further study. New nails are being launched, constructed with stronger material. This means the slender nails will in future have comparable strength to the current larger nails and withstand immediate full weight bearing. It would be undesirable if the current widespread practice of reaming continued unless it can be demonstrated that actual reaming improves fracture healing, rather than the fact that reaming accommodates a larger, stronger nail.
Conclusion The AO 8 mm UTN can be used with three distal locking screws when required. A controlled weightbearing regimen is also indicated. By following these instructions and controlling the failure rate, a satisfactory union rate can be achieved, comparable to those of larger reamed nails. Although time to weight bearing and time to union are longer, on the other hand, reaming is largely avoided. Thus, this method is a useful alternative to the practice of reaming all fractures and using large diameter nails. The advantages of the ‘unreamed’ technique are that bone stock is preserved, allowing for more reaming potential, for example in the case of infection. The operation is quicker and potentially safer. The risk of thermal osteonecrosis is largely avoided as are the adverse inflammatory effect of tissue
K. Sehat et al. trauma secondary to reaming–—particularly beneficial for the management of polytrauma. With the introduction of stronger slender nails, further research is needed to establish whether reaming itself hastens fracture healing or the earlier weight bearing and lower hardware failure rates associated with the current larger nails.
References 1. Angliss RD, Tran TA, Edwards ER, Doig SG. Unreamed nailing of tibial shaft fractures in multiply injured patients. Injury 1996;27(4):255—60. 2. Bhandari M, Guyatt GH, Tong D, et al. Reamed versus nonreamed intramedullary nailing of lower extremity long bone fractures: a systematic overview and meta-analysis. J Orthop Trauma 2000;14(1):2—9. 3. Brinker MR, Cook SD, Dunlap JN, et al. Early changes in nutrient artery blood flow following tibial nailing with and without reaming: a preliminary study. J Orthop Trauma 1999;13(2):129—33. 4. Court-Brown CM, Will E, Christie J, McQueen MM. Reamed or unreamed nailing for closed tibial fractures. J Bone Joint Surg (Br) 1996;78-B:580—3. 5. Giannoudis PV, Smith RM, Bellamy MC, et al. Stimulation of the inflammatory system by reamed and unreamed nailing of femoral fractures. J Bone Joint Surg (Br) 1999;81-B(2):356— 61. 6. Gregory P, Sanders R. The treatment of closed unstable tibial shaft fractures with unreamed interlocking nails. Clin Orthop 1995;315:48—55. 7. Haddad FS, Desai K, Sarkar JS, Dorrell JH. The AO unreamed nail: friend or foe. Injury 1996;27(4):261—3. 8. Kneifel T, Buckley R. A comparison of one versus two distal locking screws in tibial fractures treated with unreamed tibial nails: a prospective randomised clinical trial. Injury 1996;27(4):271—3. 9. Krettek C, Schandelmaier P, Tscherne H. Nonreamed interlocking nailing of closed tibial fractures with severe soft tissue injury. Clin Orthop Relat Res 1995;315:34—47. 10. Melcher GA, Ryf Ch, Leutenegger A, Ruedi Th. Tibial fractures treated with the AO unreamed tibial nail. Injury 1993;24(6):407—10. 11. Pape HC, Auf’m’Kolk M, Paffrath T, et al. Primary intramedullary femur fixation in multiple trauma patients with associated lung contusion–—a cause of posttraumatic ARDS? J Trauma 1993;34:540—7. 12. Schandelmaier P, Krettek C, Rudolf J, Tscherne H. Outcome of tibial shaft fractures with severe soft tissue injury treated by unreamed nailing versus external fixation. J Trauma 1995;39(Oct 4):707—11.
www.elsevier.com/locate/injury
The AO 8 mm solid tibial nail is not defunct K. Sehat *, A. Aladin, D. Calthorpe Derbyshire Royal Infirmary, London Road, Derby DE1 2QY, UK Accepted 15 May 2006
KEYWORDS Unreamed tibial nail (UTN); AO tibial nail; Tibial fracture; Intramedullary nailing; Reaming; Non-reamed
Summary The AO 8 mm unreamed tibial nail (UTN) is an established implant that has in some publications been associated with high rate of distal locking screw breakage and failure. Larger reamed nails are now increasingly favoured. We have used the 8 mm UTN employing all three available distal screws when appropriate and with a restricted initial weight-bearing regimen. Our experience has been satisfactory with 95% union rate and no adverse effect of distal locking screw breakage. This slender nail requires less frequent reaming which may be an advantage in at least some situations. We suggest that it should be considered an alternative to larger reamed nails and can perform satisfactorily with appropriate application. # 2007 Elsevier Ltd. All rights reserved.
Introduction The management of the fractured tibia, despite its frequent occurrence remains the subject of debate. In the senior author’s institution, for several years, the senior author’s preference and the most commonly used device has been the AO solid 8 mm unreamed tibial intramedullary nail (AO UTN). It uses two proximal and three distal locking screws. The small diameter of the nail necessitates relatively small diameter 3.9 mm locking screws. In our experience it had produced satisfactory results but it came to our attention that preference is now given in the literature and in common practice to larger diameter reamed nails. One study has even
recommended against the use of the 8 mm UTN.4 On the other hand, attention is now also paid to the adverse systemic inflammatory effects of trauma and surgery for trauma, notably the reaming of long bones. Another concern is the risk of thermal osteonecrosis caused by exuberant reaming. We felt that the poor results reported4 for the UTN may have been related to the method by which it was employed, in particular relating to the number of distal locking screws and the weight-bearing regimen. However, given the reported failure rate, we have reviewed our own results with the UTN and found them to be satisfactory.
Patients and method * Corresponding author at: 18 Covent Gardens, Nottingham NG12 2NF, UK. Tel.: +44 7946 471546. E-mail address: [email protected] (K. Sehat).
The hospital trauma theatre logbook was examined and 80 consecutive patients identified who had been
0020–1383/$ — see front matter # 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.injury.2006.05.024
The AO 8 mm solid tibial nail is not defunct
1301
treated with this device from 1997 to 2002. Hospital case notes and radiographs were studied. Closed and open fractures were all included. All fractures were displaced and unstable, requiring internal fixation and one case involved prophylactic nailing for a malignant lytic lesion. Some patients will have a very narrow medullary canal and require reaming even to accommodate an 8 mm nail, however, using this slender nail minimises the amount of reaming that is required. Our practice is to use two distal locking screws with mid-shaft fractures if a tight interference fit has been obtained. Otherwise, and with distal shaft and metaphyseal fractures, three distal locking screws are used (Fig. 1). Patients are mobilised non-weight bearing initially and followed up in the outpatient clinic. Full weight bearing is permitted when radiological signs of early union appear. This, practice is in accordance with the manufacturers instructions.
Results Of 80 patients, 55 were male and 25 were female. The mean age was 43 years. Fifteen patients were noted to have an osteopenic plain radiograph appearance. One patient with a malignant lytic lesion had a prophylactic nailing. Seventy-five fractures involved the shaft (AO type 42) and four fractures the metaphysis (AO type 43) supplemented with percutaneous screws (Fig. 2). The AO classifications of the fractures are shown in Table 1. In 71 cases the fibula was also fractured. The lead surgeon was a consultant in 36 cases, a trainee with appropriate supervision in 39 cases and joint consultant and trainee in five cases. Minimal reaming was required to accommodate the 8 mm nail in 10 cases with very narrow medullary canals. Sixty-six cases were unreamed whilst in the remaining four cases, the operation note was unclear on whether or not reaming had been employed. In accordance with our practice, 28 cases had required three distal locking screws and 49 cases two screws. (In one case only one screw had been used.) In seven cases distal locking screws broke only at a late stage and no adverse event was related to these. Dynamisation was performed in 20 cases and in three of those by removing distal locking screws (in cases with inadequate space proximally for nail protrusion following dynamisation). A further five patients requested removal of distal screws that were symptomatic, following union. Six patients were lost to follow up as they left the area and one patient died of an unrelated cause.
Figure 1 Three distal locking screws with fracture with distal extension.
Complications included one nail that was too long and was revised the next day, and one broken nail in a non-compliant, morbidly obese diabetic patient with an insensate foot who unfortunately sustained a further fall and fractured the nail. Three distal locking screws had been used and these remained intact. This was revised to a larger reamed nail and united. Two further nails were also revised due to non-union. With these four cases failing to unite, the union rate was 95% in the 73 patients followed up. Radiographic union was defined as cortical continuity on AP and lateral views in keeping with the definition used in a significant previous study of this
1302
K. Sehat et al.
Figure 2
Nail supplemented with percutaneous screw fixation of distal extension into ankle joint.
implant.4 Radiographic union occurred at a mean of 19 weeks (range 6—49 weeks). The mean interval to permission to full weight bearing (when callus was seen or at discretion of clinician) was 12 weeks
(range 0—23 weeks). Patients with transverse fractures had been allowed full weight bearing even in the absence of callus at 6 weeks or earlier with no adverse consequence.
The AO 8 mm solid tibial nail is not defunct
1303
Table 1 AO classification of fractures and their frequency AO classification
Frequency
42A1 42A2 42A3 42B1 42B2 42B3 42C1 42C2 42C3 43A1 43C1 43C2 Others
18 15 12 9 4 3 4 3 3 1 2 1 5
Discussion In support of our findings, a study by Gregory and Sanders6 in 1995 reported satisfactory results with the use of the AO unreamed tibial nail. The mean time to union was 16 weeks. No broken nails occurred in their series and only one complication arising from locking screw breakage was seen (in a non-compliant patient). Melcher et al.10 reported their use of the AO UTN with satisfactory results and although they observed distal locking screw breakages, given that their weight-bearing regimen was in a controlled manner, they did not experience any complication related to screw breakage. Similarly, Angliss et al.1 noted that distal locking screw breakage could be avoided by restriction of weight bearing in the first 6 weeks. The fact that the number of locking screws is important is highlighted by a study by Kneifel and Buckley8 who compared the performance of one versus two locking screws in tibial nails and found that one screw fails significantly more commonly than two screws (Fig. 3). Pape et al.11 have reported deterioration in pulmonary function with reaming of the femur. They suggest that an unreamed nail may be more suitable for predisposed patients with concomitant pulmonary trauma. Studies measuring rises in inflammatory mediators with major trauma followed by surgical stabilisation have recorded a ‘‘second hit’’ with the surgery. This is associated with an increased incidence of systemic complications and a worse prognosis.5 Bone blood supply is also affected by reaming.3 There is therefore some evidence for avoiding reaming if possible. Our experience with the AO 8 mm UTN suggests that if the device is used to its optimal advantage with three distal locking screws when needed, it achieves a satisfactory union rate; comparable with
Figure 3 Inconsequential distal locking screw breakage if only two screws are used. (Weight bearing commenced after callus formation.)
other types of tibial intramedullary nails. The previously reported series4 comparing this nail with a larger reamed device found a high failure rate associated with a higher early distal locking screw breakage rate with the UTN. Given our findings, this discrepancy may be attributable to the number of distal locking screws used and also the weight-bearing regimen. The use of the available third distal screw would be expected to decrease locking screw breakage rate and hence overall nail failure rate. Limiting weight bearing in the initial post-op period may be seen as a disadvantage and it is also possible that we have been too cautious in this respect. Time to union is also quicker with earlier weight bearing in other studies.2,4,7 However, we would suggest that using a slender unreamed tibial nail, three distal locking screws when needed and non-weight bearing in the initial post-op period is an alternative approach to the use of larger reamed nails
1304 with immediate full weight bearing. The union rates are comparable. Thus the 8 mm UTN remains a satisfactory option in the treatment of tibial fractures and largely avoids the need for reaming. This technique has also been advocated for the treatment of tibial shaft fractures with severe soft tissue injury and shown to be superior to external fixation.9,12 We note the literature supporting the use of reaming as a means of improving union rate and time to union.2,4,7 However, it is not clear from the current literature whether the improved performance of the reamed nails are attributable to the effect of reaming per se or the fact that reaming allows a larger nail to be implanted with a lower hardware failure rate in those series and hence a better ‘mean’ time to union in the series. We feel this question is worthy of further study. New nails are being launched, constructed with stronger material. This means the slender nails will in future have comparable strength to the current larger nails and withstand immediate full weight bearing. It would be undesirable if the current widespread practice of reaming continued unless it can be demonstrated that actual reaming improves fracture healing, rather than the fact that reaming accommodates a larger, stronger nail.
Conclusion The AO 8 mm UTN can be used with three distal locking screws when required. A controlled weightbearing regimen is also indicated. By following these instructions and controlling the failure rate, a satisfactory union rate can be achieved, comparable to those of larger reamed nails. Although time to weight bearing and time to union are longer, on the other hand, reaming is largely avoided. Thus, this method is a useful alternative to the practice of reaming all fractures and using large diameter nails. The advantages of the ‘unreamed’ technique are that bone stock is preserved, allowing for more reaming potential, for example in the case of infection. The operation is quicker and potentially safer. The risk of thermal osteonecrosis is largely avoided as are the adverse inflammatory effect of tissue
K. Sehat et al. trauma secondary to reaming–—particularly beneficial for the management of polytrauma. With the introduction of stronger slender nails, further research is needed to establish whether reaming itself hastens fracture healing or the earlier weight bearing and lower hardware failure rates associated with the current larger nails.
References 1. Angliss RD, Tran TA, Edwards ER, Doig SG. Unreamed nailing of tibial shaft fractures in multiply injured patients. Injury 1996;27(4):255—60. 2. Bhandari M, Guyatt GH, Tong D, et al. Reamed versus nonreamed intramedullary nailing of lower extremity long bone fractures: a systematic overview and meta-analysis. J Orthop Trauma 2000;14(1):2—9. 3. Brinker MR, Cook SD, Dunlap JN, et al. Early changes in nutrient artery blood flow following tibial nailing with and without reaming: a preliminary study. J Orthop Trauma 1999;13(2):129—33. 4. Court-Brown CM, Will E, Christie J, McQueen MM. Reamed or unreamed nailing for closed tibial fractures. J Bone Joint Surg (Br) 1996;78-B:580—3. 5. Giannoudis PV, Smith RM, Bellamy MC, et al. Stimulation of the inflammatory system by reamed and unreamed nailing of femoral fractures. J Bone Joint Surg (Br) 1999;81-B(2):356— 61. 6. Gregory P, Sanders R. The treatment of closed unstable tibial shaft fractures with unreamed interlocking nails. Clin Orthop 1995;315:48—55. 7. Haddad FS, Desai K, Sarkar JS, Dorrell JH. The AO unreamed nail: friend or foe. Injury 1996;27(4):261—3. 8. Kneifel T, Buckley R. A comparison of one versus two distal locking screws in tibial fractures treated with unreamed tibial nails: a prospective randomised clinical trial. Injury 1996;27(4):271—3. 9. Krettek C, Schandelmaier P, Tscherne H. Nonreamed interlocking nailing of closed tibial fractures with severe soft tissue injury. Clin Orthop Relat Res 1995;315:34—47. 10. Melcher GA, Ryf Ch, Leutenegger A, Ruedi Th. Tibial fractures treated with the AO unreamed tibial nail. Injury 1993;24(6):407—10. 11. Pape HC, Auf’m’Kolk M, Paffrath T, et al. Primary intramedullary femur fixation in multiple trauma patients with associated lung contusion–—a cause of posttraumatic ARDS? J Trauma 1993;34:540—7. 12. Schandelmaier P, Krettek C, Rudolf J, Tscherne H. Outcome of tibial shaft fractures with severe soft tissue injury treated by unreamed nailing versus external fixation. J Trauma 1995;39(Oct 4):707—11.