The AO unreamed nail: friend or foe

Copyright

0

1996

Vol. 27, No. 4, pp. 261-263, 1996 i+uy Elsevier Science Ltd. All rights reserved Printed in Great Britain OOZO-1383/96 $15.00 + 0.00

ELSEVIER

OOZO-1383(95)00160-3

The A0

unreamed

nail: friend

or foe

F. S. Haddad, K. Desai, J. S. Sarkar and J. H. Dorrell Department

of Orthopaedics,

The Lister Hospital, Stevenage, Herts, UK

Twenty-nine tibia1 shaft fractures were stabilized with the A0 unreamed tibia1 nail. These included 13 type A fractures, II type B fractures and five type C injuries. Fourteen of the fractures were open. The A0 unreamed tibia1 nail wasthe primarydevice used in all cases. Our series suggests that this is an easy device to insert and that its multiple locking options confer an advantage for the management of distal fractures. It also has a low soft-tissue complication rate. There was a delay in full patient mobilization and in the progression to fracture union. There wasalsoa significant degree of implantfailure with screw breakage in 21 per cent. This necessitated a high rate of secondary operative intervention. The high incidence (~5 per cent) of anterior knee pain was alsoworrying and frequently necessitated nail removal. We feel that this implant may still have a role for distal fracturesand in the multiply injured patient but do not feel that, in its current form, it is the ideal implant for the majority of tibia1 shaft fractures. Copyright 0 1996 Elsevier Science Ltd.

Injury, Vol. 27,

No.

4, 261-263,

1996

Introduction Tibia1fracture managementhas changed dramatically over the past 20 years but remainsa challenging and controversial areal. Locked intramedullary nailing has become a reliable and accepted method of treating tibial shaft fractures. Misgivings have however been expressed regarding the ill-effects of intramedullary reaming with particular emphasis on the destruction of the endosteal . This is thought to compromise bone blood supply z*3 which is already partly devascularized and to increasethe infection rate. The use of an unreamed nail is therefore particularly attractive in open fractures, as it combines the advantages of intramedullary fixation in terms of maintenance of alignment and soft-tissue management, with minimal damage to the tibia1 blood supply. It also facilitates patient compliance when compared with external fixatior?. Moreover, subsequent reamed exchange nailing remains an option. The A0 unreamed nail is one such unreamed nail; it consists of a solid rod tapered superiorly with an obtuse bend leading to a triangular distal two-thirds. The tip is bevelled to guide the nail along the posterior tibia1cortex. Interlocking holes in two planes both proximally and distally allow a combination of locking possibilities and widen its scope. This nail was initially marketed as a temporary implant, but some authors advocate its use for permanent fixationj. An attempt was made to use it as a definitive implant in our

centre. We have reviewed these cases-in attempt to illustrate the advantages and disadvantages of this device and define its role in tibial fracture management.

Materials

and methods

Between June1992 and May 1994,29 tibial shaft fractures were stabilized at the Lister Hospital using the A0 unreamed tibia1 nail. These were performed under general anaesthesiawithout using a fracture table, skeletal traction or a touniquet. Antibiotic prophylaxis with at least three dosesof a secondgeneration cephalosporin was usedin all cases. Thorough wound toilet and debridement was performed for all open fractures. The fracture was reduced manually and a patellar tendon splitting approach was used.With the knee flexed to a right angle, the entry point was establishedand the nail introduced with the minimum of force and proximal locking wasperformed using the jigs provided. A radiolucent drill aided distal locking. The patients were allowed to bear partial weight assoon as the state of the soft tissuesand pain permitted. Full weight bearing was allowed when the fracture was deemed axially stable:this varied from 5 to 14 weeksfrom the time of nailing. Clinical union was defined as painlesswalking with a non-tender fracture site and bridging callus on two radiographic views. Average follow-up was 14 months with a range of 6 to 28 months.

Results Patients and fractures Follow-up was possiblefor all the 29 patients and fractures treated with the A0 unreamed nail. These consistedof 20 males and nine femaleswith an average age of 29 (range Z7-74). All were skeletally mature. Eighteen fractures were right sided and 11 left sided. There were 11 high-energy injuries (road traffic accidents, industrial accidents)and 18 low-velocity injuries (predominantly sporting). The fractures have been subclassifiedin Tables! and II using A06 and Gustilo’ criteria. Four cases were associated with multisystem injuries but all the patients survived. Table I. Locationof tibia1shaftfracture Proximal third Middle third Distal third

4 16 9

(14%) (55%) (31%)

Injury:

262

International

Procedure In all cases,unreamed nailing was the primary form of fixation. In IO casesthe procedure was performed within 8 h, in IO further caseswithin 24 h and the rest within 72 h of injury. A Consultant performed the operation in six cases,an Associate Specialist in 12 cases and Registrars Table II. Subclassification

of fractures

A 0 C

of the Care of the Injured

Vol. 26, No. 8, 1995

performed I I operations. The average operating time was 64 min (range 40-135 min). Nail lengths varied from 300 to 360 mm; an 8 mm nail was usedin 25 of the casesand a 9 mm nail in the others. All were locked distally and 26/29 were locked proximally. The only major intraoperative problems noted were one broken drill and two very distal fractures which necessitated open reduction. Separate cancellousscrewswere used to control ankle fractures on two occasions. Union

Open Type of fracture

Journal

Number

I

II

III

13 (45%) 11 (38%) 5 (17%)

4 4 1

2 2

1 1

Figure 1. Anteroposterior radiograph 26 weeks after a Grade I open midshaft fracture. The distal locking screws were removed after II weeks. The remnant of the proximal locking screw was a temporary obstruction at the time of exchange nailing.

Clinical and radiological union was eventually achieved in 28 of the 29 cases(TableIII). The last case is awaiting exchange nailing. Average time to union was 22 weeks (range 13-43 weeks). Thirteen caseswere ‘dynamized’ by removal of locking screwswhen no evidence of union was present after 10 weeks (8 to 12 weeks).Four casesrequired

Figure 2. Distal locking screw failure in a distal third fracture.

Table III. Fracture union in relation to soft tissue injury Average Type of fracture Closed Grade I open Grade II open Grade III open

Number

of fractures 14 9 4 1

Secondary

intervention 4 4 4 1

time to union (weeks) 19 21 33 30

Haddad

et al.: The A0

unreamed

nail: friend or foe

reamed exchange nailing 20 to 34 weeks from the primary procedure (FigureI). In one casea fibular osteotomy was also necessary.Bone grafting was not used asa secondary procedure in this series. Complications

These included only one caseof deep infection in a distal comminuted type C fracture which had been opened at the time of surgery. Union was nonetheless achieved in 26 weeks after removal of the nail. No compartment syndromes occurred and there were no soft t-issueproblems. The interlocking screwsbroke in six cases(21 per cent) (Figure.2) and led to loss of reduction in two cases.The broken screws complicated both nail removal and the insertion of a reamed nail in two cases.Shortening of 1.5 cm was noted in one patient and an external rotation deformity of 15” in another. There were no cases of anteroposterior or mediolateral instability. Eighteen patients complained of ankle stiffnessbut this invariably respondedto physiotherapy. Anterior knee pain was a more significant complaint in 16 patients (55 per cent) and hasalready necessitatednail removal in 11 cases. As yet there have been no refractures.

Discussion In our experience, learning how to use the A0 unreamed nailing system has been easy with no associatedtechnical difficulties. It does not require the use of a fracture table, and avoids the complications of calcanealpin traction. The ‘figure of four’ position of the leg facilitates distal locking and reducesfluoroscopy time. Its speedof insertion is very helpful in the unfit or multiply injured patient. There were also remarkably few soft tissue complications. The A0 unreamed nail also allows rigid stabilization of some difficult distal fractures by use of its diverse anteroposterior and mediolateral locking capabilities. Our findings cannot however support the use of this device as a definitive implant. The high secondary intervention rate and slow time to union confirm that this nailing system doesnot improve the adverse local biology of these fracture?. Preservation of the endosteal blood supply must be weighed against the bone graft effect of reaming and the beneficial fracture healing effects of early weight bearing9. There was also a significant implant failure rate. Melcher et aL5 suggest that screw breakage only occurs in the partial weight-bearing phase and does not interfere with fracture healing. In our series, all the screw failures presented after the initiation of full weightbearing and led to loss of position in two cases. Furthermore, the distal part of the screwsbecamea hindrance at the time of nail removal or exchange nailing. We have noted a very high rate of anterior knee pain in these patients. We suggest that this may be related to the very proximal entry point used for this device“‘. Moreover, we have noted that this device is leasthelpful in the complex open fractures for which it was mooted, with all the grade II or III fractures in this seriesrequiring second operations.

263

The use of a solid unreamed device in tibia1 fracture managementremains a theoretically attractive idea’. This would provide a rapid procedure which iswell tolerated by patients and still leaves the scope for later reamednailing. It would particularly be indicated in multiple injuries, in unfit patients and in distal and open fractures. In practice however, the useof the A0 unreamednail doesnot lead to a better local biological result. Furthermore, it necessitates slower mobilization, the acceptance of a high rate of delayed union, and an increased frequency of secondary intervention. Until more securelocking bolts are available, we feel that the predominant role of the A0 unreamednail remains as a temporary implant in those few caseswere reaming is contraindicated.

References 1 Watson JT. Treatment of unstable fractures of the shaft of the tibia. ] Bone Joint Surg [Am] 1994; 76A: 15 75. 2 Whittle AP, Russel TA, Taylor JC and Lavelle DG. Treatment of open fractures of the tibia1 shaft with the use of interlocking nailing without reaming. ] Bone Joint Surg [Am] 1992; 74A: 1162. 3 Klein MPM, Rahn BA, Frigg R, Kessler S and Perren SM. Reaming versus non-reaming in medullary nailing: interference with cortical circulation of the canine tibia. Arch Ortkop Trauma Surg 1990; 109: 314. 4 Tometta III P, Bergman M, Watnik N, Berkowitz G and Steuer J. Treatment of grade IIIB open tibia1 fractures. ] Bone \oinf Surg [BY] 1993; 75B: 13. 5 Melcher GA, Ryf C, Leutenegger A and Ruedi T. Tibia1 fractures treated with the tibia1 A0 nail. fnjclry 1993; 24: 407. 6 Muller ME, Allgijwer M, Schneider R and Willenegger H. Manual of Infernal Fixation, 3rd Ed. Berlin, Heidelberg, New York: Springer-Verlag. 7 Gustilo RB and Anderson JT. Prevention of infection in the treatment of one thousand and twenty five open fractures of long bones. Retrospective and prospective analyses. ] Bone Joint Surg [Am] 1976; 58A: 453. 8 BoneLB, Kassman S,StegemanP and France J. Prospective study of union rate of open tibia1 fractures treated with locked unreamed intramedullary nails. ] Orfkop Trauma 1994; 8: 45. 9 Court-Brown CM, McQueen MM, Quaba AA and Christie J. Locked intramedullary nailing of open tibia1 fractures. ] Bone joint Surg [BY] 1991; 73B: 959. 10 Henley MB, Meier M and TencerAK. Influences of some design parameters on the biomechanics of the unreamed tibia1 intramedullary nail. / Ortkop Trauma 1993; 7: 3 11.

Paper accepted 25 August 1995.

Requests for reprints should be addressed to: F. S. Haddad, 46B Hanover Gate Mansions, Park Road, London NW1 4SN, UK.