- Email: [email protected]
Extended use of the k wire and the orthopaedic screw:
Injury, Int. J. Care Injured 31 (2000) 575±583
www.elsevier.com/locate/injury
Extended use of the k wire and the orthopaedic screw: the Fixclip2 Project p Allen S. Baker* Northampton General Hospital, England, UK Accepted 4 April 2000
Abstract The results of the ®rst 280 ®xations with the Fixclip2 systems are reported. The intended advantages of increased ®xation accuracy and versatility have been realised. Two hundred and ®fty four ®xations have been followed-up to union; there have been three deep infections, two persistent non-unions, and 12 ®xation failures requiring revision. A range of sizes has allowed use of the system with screws from the small and basic fragment sets with wires from 1.2 to 3 mm diameter. Its use in the management of paediatric conditions, intra-articular fractures, fractures in osteoporotic bone and as a blade plate substitute are illustrated. Its potential as a biologically and mechanically eective means of bone ®xation is discussed. 7 2000 Elsevier Science Ltd. All rights reserved.
1. Introduction The Fixclip2 project, started 7 years ago, challenged the assumption that progress only followed when ®xation devices became more specialised, sophisticated and expensive. It sought to improve ®xation using implants and techniques familiar to all orthopaedic surgeons by extending the role of stainless steel wires and standard bone screws; all familiar items, available in any orthopaedic operating theatre. The system was designed to capitalise on contemporary knowledge of the mechanical [1] and biological [2] factors that encourage bone healing; this would hopefully make the ®xation stronger and the bone heal faster. Adjustability would allow the surgeon to perform more accurate ®xations, so important when performing Fixclip2 is a trademark of Corin Medical UK Limited. * Matthew House, 123 Tavistock Street, Bedford MK40 2SB, UK. Tel.: +44-1234-358223; fax: +44-1234-349656. E-mail address: [email protected] (A.S. Baker). p
corrective osteotomies. Modularity would make it adaptable, economical and simple to use. It was intended that the surgeon should be able to design a construct for each application and create the right balance of stability and rigidity to optimise bone healing, maintain ®xation and minimise post operative splintage. There have been no design changes of the Fixclip2 since it was ®rst introduced in February 1993. The results of the ®rst 280 ®xations using this system are reported. 2. The clips The clip is shaped like a winged washer with a convex base. The wings buttress the wires against the screw head, as shown in Fig. 1. Wires are initially captured in the clip but not gripped (captive mode; Fig. 2a). When the screw is tightened, the wires are ®rmly gripped within the clip (®xed mode; Fig. 2b). To use the clip in the conventional way, the bone must be strong. In softer and particularly cancellous bone the clip is used upside down (reversed mode;
0020-1383/00/$ - see front matter 7 2000 Elsevier Science Ltd. All rights reserved. PII: S 0 0 2 0 - 1 3 8 3 ( 0 0 ) 0 0 0 5 5 - 3
576
A.S. Baker / Injury, Int. J. Care Injured 31 (2000) 575±583
Fig. 1. The Fixclip2.
Fig. 2c) to pull the wires down onto the bone. Most cortical bone is strong enough to use the clip in the conventional way. 2.1. Use of the clip system On the articulatar side of the ®xation point, where the bone is softer, the wires are drilled into the bone, bent and ®xed to a clip which is screwed into cortical bone of the other fragment. A second clip is added in reverse mode (upside down) as near to the ®xation point as possible. Further clips and wires are added as necessary. Examples are detailed below.
Fig. 2. Use of the Fixclip2 (a) ``Captive mode'' (b) ``Fixed mode'' (c) ``Reversed mode''.
2.1.1. Upper femoral osteotomy Two wires are drilled into the femoral neck; a third larger pin is drilled into the femoral neck and used to manipulate the femoral head fragment. A clip is screwed into the cortical bone of the femoral shaft. The osteotomy is performed and the wires swung round and captured in the clip. A second clip is added in reverse mode as near to the ®xation point as possible. The manipulator pin is used to control the proximal fragment whilst ®nal positional adjustments are made and the screws tightened to grip the wires (Fig. 3). Further wires are added as necessary. For example a child of under 2 years with Developmental Dysplasia
A.S. Baker / Injury, Int. J. Care Injured 31 (2000) 575±583
577
Fig. 3. Wires in a model of the upper femur. The distal anchoring clip is placed in strong cortical bone. The proximal clip is placed in reversed mode, just distal to the osteotomy in metaphyseal bone. Two wire con®guration for the proximal femur. Distal clip is in conventional mode; proximal clip is near the osteotomy in reversed mode. Wires are bent to meet the clips.
of the Hip (DDH) would be ®xed with two 1.2 mm wires ®xed with small fragment set screws and two clips. An adolescent or adult would probably require three or four 2 mm wires with three or four clips, depending on the stability of the osteotomy. 2.1.2. Humeral neck fractures in the adult Four 2 mm wires are necessary. Two pairs are drilled into the humeral head either side of the bicipital groove and each pair ®xed with two clips (Fig. 4). 2.2. Mechanical studies Pull-out tests have been performed in the laboratory
with an Houns®eld tensometer. A torque screwdriver was used at surgery to determine a range of normally accepted screw tightness. Grip strength was then compared in the laboratory to screw tightness. There was a linear relationship through the clinical range of screw torque.
3. Results Two hundred and eighty ®xations have been performed in 239 patients. Two hundred and ®fty have documented union, four elderly patients died before
578
A.S. Baker / Injury, Int. J. Care Injured 31 (2000) 575±583
Table 1 Main applications
3.1. Complications
Application
n
Upper femoral osteotomies Fractured neck of humerus Femoral fractures Upper tibial osteotomies Fractured neck of femur Tibial plateau fractures Periprosthetic fractures Humeral shaft fractures Elbow fractures Ankle fractures Supramalleolar osteotomies Slipped upper femoral epiphyses Pelvic ®xations Established non-unions Revisions of failed ®xations (other systems)
73 25 19 16 14 14 11 13 10 9 6 4 8 19 22
There have been three deep infections. One, in a 72 year old man with a lower tibial fracture, resolved after treatment with antibiotics; the fracture united and the metalware was removed 4 months later. The second case was a 92 year old lady where fusion was attempted after a total knee replacement had become infected. This later responded to antibiotics. The third infection occurred in another surgeon's patient and has been lost to follow-up. Twenty-nine cases have been revised. In 10 cases revision surgery has been performed successfully for ®xation failure, two required repositioning of a protruding wire and 14 had persistent non-unions. Three cases were revised to adjust bone alignment. Two patients with humeral neck fractures and one
bone union, 13 have been lost to follow-up, three have been revised to hemiarthroplasties and two have been left with persistent non-unions. Eight patients await union. The main applications are shown in Table 1.
Fig. 4. This 63 year old man sustained a fracture dislocation of his shoulder. Typical proximal humeral ®xation was performed using two pairs of 2 mm wires either side of the bicipital groove.
Fig. 5. Trans-epiphyseal ®xation in a 14 year old boy through an anterolateral incision.
A.S. Baker / Injury, Int. J. Care Injured 31 (2000) 575±583
579
with a fractured neck of femur underwent revisions to hemiarthroplasties. Only two patients have been left with persistent non-unions. The ®rst, a 69 year old lady who had originally presented with an established non-union of the humeral neck, declined further surgery. The second, a 92 year old lady with an infected knee replacement where fusion of the knee was attempted, developed a multi-resistant Staphylococcus aureus infection elsewhere. She was un®t for further surgery.
4. Discussion The system has been used mainly in adult fracture surgery but also extensively in paediatric surgery. Osteotomy alignment can be ®ne tuned to gain the ®nal position. Wires can bridge epiphyseal plates to obtain strong ®xation without damaging the growth plate (Fig. 5). In this overweight 14 year old boy a medial approach was precluded by soft tissue damage and ®xation had to be performed through an anterolateral approach. Normally, in such cases, the wires are removed 4 or 5 months later, once fracture consolidation has occurred. The system has been used very eectively to ®x slipped upper femoral epiphyses (Fig. 6). In this case one side had been ®xed with a cannulated screw by another surgeon. Three years later it can be seen that growth has continued on the side where the clip was used. Subsequent removal, so often a problem, is Fig. 7. Fixation of a comminuted trimalleolar fracture using small fragment screws.
Fig. 6. Slipped under femoral epiphysis. After initial ®xation (above) and below, 3 years later shows continued growth on the right.
simple. Two millimetre wires have been used and there have been no complications in this group. Complex intr-articular fractures can be accurately ®xed and anchored where there is bone stock and adequate soft tissue cover (Fig. 7). This illustrates ®xation of widely comminuted fractures of the posterior, medial and lateral malleolli. In the author's practice, the system has superseded the blade plate and condylar screw. Using 3 mm wires, simple but immensely strong ®xation has been achieved. In the case illustrated in Fig. 8 malunion had left a 66 year old lady with a 508 ®xed ¯exion deformity. After removing the Dynamic Condylar Screw (DCS) there was a large defect in the bone and a signi®cant deformity to correct. The wires were drilled into the subcortical bone and the proximal ®xation spread over
580
A.S. Baker / Injury, Int. J. Care Injured 31 (2000) 575±583
Fig. 8. Revision of a malunited supracondylar femoral fracture using 3 mm wires and basic fragment set screws.
Fig. 9. Combined internal and external ®xation of Schatzker Type 6 fracture using 2 mm wires and basic fragment set screws.
A.S. Baker / Injury, Int. J. Care Injured 31 (2000) 575±583
a signi®cant length of the femur. Within 3 months this lady was fully weight bearing. The ``gold standard'' for ®xation in this area is said to be the DCS which, by contrast, damages bone stock and requires an intact distal bone block of at least 4 cm to achieve ®xation [3]. The system has been used with external ®xation in three cases to treat comminuted fractures with minimal soft tissue disruption. Indirect reduction has been performed with a lag screw on a reversed clip as seen in the middle clip of Fig. 9. In this case, concerning a 27 year old lady, the external ®xator has been removed after 6 weeks and mobilisation commenced in a cast brace. Unlike plates, the majority of the implant lies o the bone. Bone healing has usually been rapid. Gaps left after opening-wedge osteotomies have rapidly ®lled in without grafting. Presumably this re¯ects biological and mechanical factors.
Fig. 10. Periprosthetic femoral fracture ®xed with 3 mm wires drilled into the bone distally and basic fragment set screws. Note the abundant new bone formation 2 months later (on the right).
581
Advantages are seen in the management of periprosthetic fractures where screw placement and bone viability can be a problem with plating (Fig. 10). A most challenging group of injuries have been the proximal humeral fractures where ®xation failure has occurred in four cases. It became clear that a single pair of wires was insucient and two pairs of wires either side of the bicipital groove were required in most cases to give stability. Twenty-one cases have since been ®xed in this way without failure. Radiographs do not really re¯ect the strength of the ®xations. The supposition that the wires can only act as tension bands has not been the author's experience. Like plates, the wires have been used to neutralise and buttress ®xations. Compression has to be applied with a lag screw. Appropriately anchored wires are as strong as plates, without the stress risers at the plate holes. When a third wire is added, like scaolding, the construction assumes another dimension. In the 35 patients where the heavy duty 3 mm system was used to ®x the adult femur there were three periprosthetic femoral shaft fractures that required revision early in the series. When the author altered his practice and placed or drilled the wires into bone (Figs. 8 and 10) there were no further ®xation failures in the femoral shaft fracture group. Modularity allows the surgeon to create the rigidity and strength for ®xation that is required. Post-operative care has been no dierent than for other well ®xed fractures. The patients restrict weight bearing until the fractures unite. As an example the patient illustrated in Fig. 9 was splinted in a cast brace for 3 months post operatively. The femoral fractures were not splinted. Disappointing results following the use of sophisticated implants have been reported. This is typi®ed by articles from Garnavos et al. [4] and Majkowski and Baker [5]. Garnavos et al. reported the results of treatment of proximal femoral fractures with a reconstruction nail. In approximately half of their cases intraoperative problems were reported and only one of their patients bore weight before the bone could reasonably expect to have united. Seven of their 13 patients over the age of 60 failed ever to achieve full weight bearing. This may suggest the ®xation in such cases should be geared to achieving rapid bone union rather than early weight bearing through the implant. Inserting these massive implants damages bone stock and delays bone healing, and, so it seems in more complex cases, fails to lead to early weight bearing. It has been our experience that revision of such cases reveals large segments of devascularised bone. Majkowski and Baker reported the results of the ®rst 50 interlocking nailings; a number of surgeons performed the operations and the number of complications re¯ected that inexperience. Most orthopaedic surgeons are compe-
582
A.S. Baker / Injury, Int. J. Care Injured 31 (2000) 575±583
Fig. 11. Fixation of an ununited proximal humeral fracture.
tent, but few have more than occasional experience of specialised implants. Indications for use of the system have expanded as con®dence has grown. In poor bone stock longer and thinner wires are used to distribute ®xation along the bone and take stress o the screw±bone interface. Good purchase can be obtained in one fragment by drilling the wires into the bone. This 54 year old (Fig. 11), heavy smoking alcoholic and diabetic, eventually underwent surgery for a non-union 1 year after sustaining this fracture. The bone healed rapidly. The system has ful®lled and exceeded expectation. It has versatility to ®x bone of most shapes and sizes. Femoral osteotomies have been ®xed in children of 12 months with developmental dysplasia of the hip, and fully grown adults with painful dysplasia. Perren [6], in a recent editorial, concludes that many of the mechanical challenges of bone ®xation have already been
addressed, but the next major challenge is a biological one. He calls for ®xation with soft tissue preservation where failure leaves a reactive or hypertrophic non union, rather than the avascular atrophic non union that is so dicult to treat. The Fixclip2 system appears to ful®ll many of these aspirations. The failures have been simple to treat as the bone stock and its blood supply has been in good condition. With experience, the mechanical problems have been addressed and ®xation failures have occurred only in new or unusual applications. The major concern is that its ¯exibility will allow the surgeon to create both eective and ineective constructs. Experience gained cautiously over 7 years has led to an understanding of the constructs required for a large number of applications. Pre-operative planning is necessary and established methods should be adhered to wherever possible.
A.S. Baker / Injury, Int. J. Care Injured 31 (2000) 575±583
References [1] Kenwright J, Goodship AE. Controlled mechanical stimulation in the treatment of tibial fractures. Clin Orthop 1989;241:36±47. [2] McKibbon B. The Biology of fracture healing in long bones. J Bone Joint Surg 1978;60B(2):150±62. [3] Harder Y, Martinet O, Barraud G-E, Cordey J, Regazzoni P. The mechanics of internal ®xation of fractures of the distal
583
femur: a comparison of the condylar screw (DCS) with the condylar plate (CP). Injury 1999;30:SA31±SA39. [4] Garnavos C, Peterman A, Howard PW. The treatment of dicult proximal femoral fractures with the Russell±Taylor reconstruction nail. Injury 1999;30:407±15. [5] Majkowski R, Baker AS. Interlocking nails for femoral fractures: an initial experience. Injury 1992;22(2):93±6. [6] Perren S. Editorial: Trends in internal ®xation. Potential, limits and requirements. Injury 1999;30:SB2±SB4.
www.elsevier.com/locate/injury
Extended use of the k wire and the orthopaedic screw: the Fixclip2 Project p Allen S. Baker* Northampton General Hospital, England, UK Accepted 4 April 2000
Abstract The results of the ®rst 280 ®xations with the Fixclip2 systems are reported. The intended advantages of increased ®xation accuracy and versatility have been realised. Two hundred and ®fty four ®xations have been followed-up to union; there have been three deep infections, two persistent non-unions, and 12 ®xation failures requiring revision. A range of sizes has allowed use of the system with screws from the small and basic fragment sets with wires from 1.2 to 3 mm diameter. Its use in the management of paediatric conditions, intra-articular fractures, fractures in osteoporotic bone and as a blade plate substitute are illustrated. Its potential as a biologically and mechanically eective means of bone ®xation is discussed. 7 2000 Elsevier Science Ltd. All rights reserved.
1. Introduction The Fixclip2 project, started 7 years ago, challenged the assumption that progress only followed when ®xation devices became more specialised, sophisticated and expensive. It sought to improve ®xation using implants and techniques familiar to all orthopaedic surgeons by extending the role of stainless steel wires and standard bone screws; all familiar items, available in any orthopaedic operating theatre. The system was designed to capitalise on contemporary knowledge of the mechanical [1] and biological [2] factors that encourage bone healing; this would hopefully make the ®xation stronger and the bone heal faster. Adjustability would allow the surgeon to perform more accurate ®xations, so important when performing Fixclip2 is a trademark of Corin Medical UK Limited. * Matthew House, 123 Tavistock Street, Bedford MK40 2SB, UK. Tel.: +44-1234-358223; fax: +44-1234-349656. E-mail address: [email protected] (A.S. Baker). p
corrective osteotomies. Modularity would make it adaptable, economical and simple to use. It was intended that the surgeon should be able to design a construct for each application and create the right balance of stability and rigidity to optimise bone healing, maintain ®xation and minimise post operative splintage. There have been no design changes of the Fixclip2 since it was ®rst introduced in February 1993. The results of the ®rst 280 ®xations using this system are reported. 2. The clips The clip is shaped like a winged washer with a convex base. The wings buttress the wires against the screw head, as shown in Fig. 1. Wires are initially captured in the clip but not gripped (captive mode; Fig. 2a). When the screw is tightened, the wires are ®rmly gripped within the clip (®xed mode; Fig. 2b). To use the clip in the conventional way, the bone must be strong. In softer and particularly cancellous bone the clip is used upside down (reversed mode;
0020-1383/00/$ - see front matter 7 2000 Elsevier Science Ltd. All rights reserved. PII: S 0 0 2 0 - 1 3 8 3 ( 0 0 ) 0 0 0 5 5 - 3
576
A.S. Baker / Injury, Int. J. Care Injured 31 (2000) 575±583
Fig. 1. The Fixclip2.
Fig. 2c) to pull the wires down onto the bone. Most cortical bone is strong enough to use the clip in the conventional way. 2.1. Use of the clip system On the articulatar side of the ®xation point, where the bone is softer, the wires are drilled into the bone, bent and ®xed to a clip which is screwed into cortical bone of the other fragment. A second clip is added in reverse mode (upside down) as near to the ®xation point as possible. Further clips and wires are added as necessary. Examples are detailed below.
Fig. 2. Use of the Fixclip2 (a) ``Captive mode'' (b) ``Fixed mode'' (c) ``Reversed mode''.
2.1.1. Upper femoral osteotomy Two wires are drilled into the femoral neck; a third larger pin is drilled into the femoral neck and used to manipulate the femoral head fragment. A clip is screwed into the cortical bone of the femoral shaft. The osteotomy is performed and the wires swung round and captured in the clip. A second clip is added in reverse mode as near to the ®xation point as possible. The manipulator pin is used to control the proximal fragment whilst ®nal positional adjustments are made and the screws tightened to grip the wires (Fig. 3). Further wires are added as necessary. For example a child of under 2 years with Developmental Dysplasia
A.S. Baker / Injury, Int. J. Care Injured 31 (2000) 575±583
577
Fig. 3. Wires in a model of the upper femur. The distal anchoring clip is placed in strong cortical bone. The proximal clip is placed in reversed mode, just distal to the osteotomy in metaphyseal bone. Two wire con®guration for the proximal femur. Distal clip is in conventional mode; proximal clip is near the osteotomy in reversed mode. Wires are bent to meet the clips.
of the Hip (DDH) would be ®xed with two 1.2 mm wires ®xed with small fragment set screws and two clips. An adolescent or adult would probably require three or four 2 mm wires with three or four clips, depending on the stability of the osteotomy. 2.1.2. Humeral neck fractures in the adult Four 2 mm wires are necessary. Two pairs are drilled into the humeral head either side of the bicipital groove and each pair ®xed with two clips (Fig. 4). 2.2. Mechanical studies Pull-out tests have been performed in the laboratory
with an Houns®eld tensometer. A torque screwdriver was used at surgery to determine a range of normally accepted screw tightness. Grip strength was then compared in the laboratory to screw tightness. There was a linear relationship through the clinical range of screw torque.
3. Results Two hundred and eighty ®xations have been performed in 239 patients. Two hundred and ®fty have documented union, four elderly patients died before
578
A.S. Baker / Injury, Int. J. Care Injured 31 (2000) 575±583
Table 1 Main applications
3.1. Complications
Application
n
Upper femoral osteotomies Fractured neck of humerus Femoral fractures Upper tibial osteotomies Fractured neck of femur Tibial plateau fractures Periprosthetic fractures Humeral shaft fractures Elbow fractures Ankle fractures Supramalleolar osteotomies Slipped upper femoral epiphyses Pelvic ®xations Established non-unions Revisions of failed ®xations (other systems)
73 25 19 16 14 14 11 13 10 9 6 4 8 19 22
There have been three deep infections. One, in a 72 year old man with a lower tibial fracture, resolved after treatment with antibiotics; the fracture united and the metalware was removed 4 months later. The second case was a 92 year old lady where fusion was attempted after a total knee replacement had become infected. This later responded to antibiotics. The third infection occurred in another surgeon's patient and has been lost to follow-up. Twenty-nine cases have been revised. In 10 cases revision surgery has been performed successfully for ®xation failure, two required repositioning of a protruding wire and 14 had persistent non-unions. Three cases were revised to adjust bone alignment. Two patients with humeral neck fractures and one
bone union, 13 have been lost to follow-up, three have been revised to hemiarthroplasties and two have been left with persistent non-unions. Eight patients await union. The main applications are shown in Table 1.
Fig. 4. This 63 year old man sustained a fracture dislocation of his shoulder. Typical proximal humeral ®xation was performed using two pairs of 2 mm wires either side of the bicipital groove.
Fig. 5. Trans-epiphyseal ®xation in a 14 year old boy through an anterolateral incision.
A.S. Baker / Injury, Int. J. Care Injured 31 (2000) 575±583
579
with a fractured neck of femur underwent revisions to hemiarthroplasties. Only two patients have been left with persistent non-unions. The ®rst, a 69 year old lady who had originally presented with an established non-union of the humeral neck, declined further surgery. The second, a 92 year old lady with an infected knee replacement where fusion of the knee was attempted, developed a multi-resistant Staphylococcus aureus infection elsewhere. She was un®t for further surgery.
4. Discussion The system has been used mainly in adult fracture surgery but also extensively in paediatric surgery. Osteotomy alignment can be ®ne tuned to gain the ®nal position. Wires can bridge epiphyseal plates to obtain strong ®xation without damaging the growth plate (Fig. 5). In this overweight 14 year old boy a medial approach was precluded by soft tissue damage and ®xation had to be performed through an anterolateral approach. Normally, in such cases, the wires are removed 4 or 5 months later, once fracture consolidation has occurred. The system has been used very eectively to ®x slipped upper femoral epiphyses (Fig. 6). In this case one side had been ®xed with a cannulated screw by another surgeon. Three years later it can be seen that growth has continued on the side where the clip was used. Subsequent removal, so often a problem, is Fig. 7. Fixation of a comminuted trimalleolar fracture using small fragment screws.
Fig. 6. Slipped under femoral epiphysis. After initial ®xation (above) and below, 3 years later shows continued growth on the right.
simple. Two millimetre wires have been used and there have been no complications in this group. Complex intr-articular fractures can be accurately ®xed and anchored where there is bone stock and adequate soft tissue cover (Fig. 7). This illustrates ®xation of widely comminuted fractures of the posterior, medial and lateral malleolli. In the author's practice, the system has superseded the blade plate and condylar screw. Using 3 mm wires, simple but immensely strong ®xation has been achieved. In the case illustrated in Fig. 8 malunion had left a 66 year old lady with a 508 ®xed ¯exion deformity. After removing the Dynamic Condylar Screw (DCS) there was a large defect in the bone and a signi®cant deformity to correct. The wires were drilled into the subcortical bone and the proximal ®xation spread over
580
A.S. Baker / Injury, Int. J. Care Injured 31 (2000) 575±583
Fig. 8. Revision of a malunited supracondylar femoral fracture using 3 mm wires and basic fragment set screws.
Fig. 9. Combined internal and external ®xation of Schatzker Type 6 fracture using 2 mm wires and basic fragment set screws.
A.S. Baker / Injury, Int. J. Care Injured 31 (2000) 575±583
a signi®cant length of the femur. Within 3 months this lady was fully weight bearing. The ``gold standard'' for ®xation in this area is said to be the DCS which, by contrast, damages bone stock and requires an intact distal bone block of at least 4 cm to achieve ®xation [3]. The system has been used with external ®xation in three cases to treat comminuted fractures with minimal soft tissue disruption. Indirect reduction has been performed with a lag screw on a reversed clip as seen in the middle clip of Fig. 9. In this case, concerning a 27 year old lady, the external ®xator has been removed after 6 weeks and mobilisation commenced in a cast brace. Unlike plates, the majority of the implant lies o the bone. Bone healing has usually been rapid. Gaps left after opening-wedge osteotomies have rapidly ®lled in without grafting. Presumably this re¯ects biological and mechanical factors.
Fig. 10. Periprosthetic femoral fracture ®xed with 3 mm wires drilled into the bone distally and basic fragment set screws. Note the abundant new bone formation 2 months later (on the right).
581
Advantages are seen in the management of periprosthetic fractures where screw placement and bone viability can be a problem with plating (Fig. 10). A most challenging group of injuries have been the proximal humeral fractures where ®xation failure has occurred in four cases. It became clear that a single pair of wires was insucient and two pairs of wires either side of the bicipital groove were required in most cases to give stability. Twenty-one cases have since been ®xed in this way without failure. Radiographs do not really re¯ect the strength of the ®xations. The supposition that the wires can only act as tension bands has not been the author's experience. Like plates, the wires have been used to neutralise and buttress ®xations. Compression has to be applied with a lag screw. Appropriately anchored wires are as strong as plates, without the stress risers at the plate holes. When a third wire is added, like scaolding, the construction assumes another dimension. In the 35 patients where the heavy duty 3 mm system was used to ®x the adult femur there were three periprosthetic femoral shaft fractures that required revision early in the series. When the author altered his practice and placed or drilled the wires into bone (Figs. 8 and 10) there were no further ®xation failures in the femoral shaft fracture group. Modularity allows the surgeon to create the rigidity and strength for ®xation that is required. Post-operative care has been no dierent than for other well ®xed fractures. The patients restrict weight bearing until the fractures unite. As an example the patient illustrated in Fig. 9 was splinted in a cast brace for 3 months post operatively. The femoral fractures were not splinted. Disappointing results following the use of sophisticated implants have been reported. This is typi®ed by articles from Garnavos et al. [4] and Majkowski and Baker [5]. Garnavos et al. reported the results of treatment of proximal femoral fractures with a reconstruction nail. In approximately half of their cases intraoperative problems were reported and only one of their patients bore weight before the bone could reasonably expect to have united. Seven of their 13 patients over the age of 60 failed ever to achieve full weight bearing. This may suggest the ®xation in such cases should be geared to achieving rapid bone union rather than early weight bearing through the implant. Inserting these massive implants damages bone stock and delays bone healing, and, so it seems in more complex cases, fails to lead to early weight bearing. It has been our experience that revision of such cases reveals large segments of devascularised bone. Majkowski and Baker reported the results of the ®rst 50 interlocking nailings; a number of surgeons performed the operations and the number of complications re¯ected that inexperience. Most orthopaedic surgeons are compe-
582
A.S. Baker / Injury, Int. J. Care Injured 31 (2000) 575±583
Fig. 11. Fixation of an ununited proximal humeral fracture.
tent, but few have more than occasional experience of specialised implants. Indications for use of the system have expanded as con®dence has grown. In poor bone stock longer and thinner wires are used to distribute ®xation along the bone and take stress o the screw±bone interface. Good purchase can be obtained in one fragment by drilling the wires into the bone. This 54 year old (Fig. 11), heavy smoking alcoholic and diabetic, eventually underwent surgery for a non-union 1 year after sustaining this fracture. The bone healed rapidly. The system has ful®lled and exceeded expectation. It has versatility to ®x bone of most shapes and sizes. Femoral osteotomies have been ®xed in children of 12 months with developmental dysplasia of the hip, and fully grown adults with painful dysplasia. Perren [6], in a recent editorial, concludes that many of the mechanical challenges of bone ®xation have already been
addressed, but the next major challenge is a biological one. He calls for ®xation with soft tissue preservation where failure leaves a reactive or hypertrophic non union, rather than the avascular atrophic non union that is so dicult to treat. The Fixclip2 system appears to ful®ll many of these aspirations. The failures have been simple to treat as the bone stock and its blood supply has been in good condition. With experience, the mechanical problems have been addressed and ®xation failures have occurred only in new or unusual applications. The major concern is that its ¯exibility will allow the surgeon to create both eective and ineective constructs. Experience gained cautiously over 7 years has led to an understanding of the constructs required for a large number of applications. Pre-operative planning is necessary and established methods should be adhered to wherever possible.
A.S. Baker / Injury, Int. J. Care Injured 31 (2000) 575±583
References [1] Kenwright J, Goodship AE. Controlled mechanical stimulation in the treatment of tibial fractures. Clin Orthop 1989;241:36±47. [2] McKibbon B. The Biology of fracture healing in long bones. J Bone Joint Surg 1978;60B(2):150±62. [3] Harder Y, Martinet O, Barraud G-E, Cordey J, Regazzoni P. The mechanics of internal ®xation of fractures of the distal
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