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MINIMALLY INVASIVE PLATE OSTEOYNTHESIS (MIPO) IN THE TREATMENT OF MULTIFRAGMENTARY FRACTURES OF THE TIBIA
Pradyumna P Pai Raiturker*, AA Salunkhe**
*Registrar; **Hon. Ass. Professor, Department of Orthopaedics, Sassoon General Hospitals, Pune.
A study to assess the role of minimally invasive plate osteosynthesis (MIPO) in the treatment of 16 adult patients of multifragmentary comminuted fractures of the tibia is presented. There were two cases of proximal tibial fractures, 11 cases of proximal diaphyseometaphyseal fractures and three cases of distal tibial fractures. All were treated with "Biological Plating" techniques using indirect reduction methods, with limited operative exposure, without opening the fracture site. All cases went to union. 62.5% cases showed radiological union between 14 and 18 weeks and remining 37.5% in 19 and 23 weeks. 82.3% cases went to full weight bearing in 23 weeks. No cases required bone grafting. Incidence of complications was very low, with only one case of superficial infection. Range of motion at knee and ankle joint was excellent. The functional outcome for long term result were rated using points, revealed excellent to good outcome in 93.75% cases with fair result in one patient.
INTRODUCTION
Plate osteosynthesis is recognized as the treatment of choice for most articular, many metaphyseal and a few diaphyseal fractures. Biological plating techniques are those in which blood supply to the fractured fragments is maximally preserved. The objective of biologic fixation is to assist physiological process of bone healing wisely and optimally with minimal amount of operative intervention.1-6 Stress is laid on maintaining a precarious balance between devascularisation and mechanical perfection.
The first attempts at which is called as biological plating date back some 20 years (Boitzy and Weber), but it has gained popularity in the 1980s. The development of indirect reduction techniques (Mast et al 1989), the development of wave plate (Brunner and Weber 1981) and the bridging plate (Heitemeyer et al 1985) brought about a basic change to fracture treatment using plates. [7]
Conventional plating techniques if applied to multifragmentary fractures lead to a variety of complications like delayed union or non-union, infection and implant failure. [8] , [9] This is because in order to achieve anatomic reduction, wide surgical exposure is necessary and the fracture fragments are stripped of the soft tissue attachments.
Biological fixation principles can be summarized as [10]
1.Repositioning and realigning by manipulation at a distance to fracture site, preserving soft tissues (Indirect reduction techniques).
2.Leaving comminuted fragments out of the mechanical construct, while preserving their blood supply.
3.Using low elastic modulus, biocompatible materials.
4.Limited operative exposure.
Minimally invasive plate osteosynthesis (MIPO)2 is one such method in which percutaneously inserted plate is fixed at a distance proximal and distal to the fracture site through minimal exposure.
MATERIAL AND METHODS
Sixteen cases of multifragmentary fractures of the tibia admitted in Sassoon General Hospitals, Pune between March 1997 and February 1999 were studied. Duration of follow-up ranged from five months to 18 months. Only closed or grade I open fractures were included.
All cases received first aid in casualty with thorough examination to find out associated injuries. Patients were subjected to routine preanaesthetic investigations and additional investigations when indicated. Standard anteroposterior and lateral radiographs were taken and the fracture classified according to AO group classification (Table 1).
TABLE 1
Fractures classified according to the AO classificationTibia fibula proximal (41) : Number of cases Fracture subtype 2 A3 Tibia fitula diaphysis (42) : B2 2 B3 4 C1 2 C2 1
C3 2 Tibia fibula distal (43) : A3 3
Calcaneal pin traction or ankle traction was given with the leg additionally immobilized in a posterior plaster splint. Strict limb elevation was given with additional chymotrypsin trypsin tablets to reduce the overall inflammatory response. Many of the patients having other bony or soft tissue injuries were treated appropriately.
The antero-posterior and lateral X-rays were evaluated for the extent of comminution and the likely length of the plate was calculated. Since usually long plates are required to span the comminuted area and such long plates are not readily available, a prior calculation is a must.
Fig 1 : Proximal and distal incisions with the fracture site unexposed illustrating the MIPO technique Surgery performed under regional anaesthesia and with a tourniquet in the supine position. A small incision is taken on one end of the fractured comminuted area without disturbing the soft tissue envelope of the fractured fragments (Fig. 1). The incision is extended right upto the bone with the periosteal tube opened. A sub-periosteal tract is made along the surface where the plate is going to be applied and extended across the fracture to the other side. The tract is done with a special doubly angled periosteal elevator available in different sizes. Sometimes the tract can be made with the plate to be used itself. The plate used depended on the anatomy and location of the fracture. AL or T buttress plate is used for proximal metaphyseal and diaphyseo-metaphyseal junctional fractures. A narrow tibia DCP is used for fractures of the diaphysis and either a T buttress or a clover leaf plate is used for the distal tibia fractures. Once the tract is made an appropriate length plate is selected so that at least 6 to 8 cortices hold is obtained on either side. A contoured plate is made to slide along the previously created tract. With the plate insitu and some traction given manually the alignment is checked using the standard anterior superior iliac spine - centre of patella-second toe guide line. An X-ray is taken to check the alignment radiologically and also to confirm the length of the plate, if it is appropriate. The plate is fixed at one end with appropriate screws (4.5 mm cortical or 6.5 mm cancellous). Initially only one screw is passed and maintaining the plate bone contact and the alignment the remaining screws are passed. With the fracture reduced by indirect means without opening the fractured area by gentle external manipulations, the distal end of the plate is marked. The plate is fixed distally with percutaneously introduced screws. The alignment is checked all the time. Use of bone holding forceps was avoided. Careful handling of the soft tissues and judicious use of the retractors is a must. No primary bone grafting was done irrespective of the comminution.
Fig 2 : Prooperative radiograph of comminuted lower third fracture tibia Contouring of the plate is a must especially for fractures of the lower end of the tibia where the plate has to be correctly contoured with approximately 25 degrees of medial angulation and 20 degrees of external rotation.11 The plate can be slided on either the medial or the lateral aspects of the tibia in the proximal end depending on the fracture geometry but for the lower end it is applied on the anteromedial surface. Associated fibular fracture was fixed only in two cases of the fracture of the distal tibia to additionally maintain length.
Fig 3 : Showing radiological union at 15 weeks after MIPO
Fig 4 : Preoperative radiograph of fracture upper third of tibia
Fig 5 : Post operative radiologaph with radiological union at 16 weeks after MIPO Post operatively limb is elevated with ankle and knee range of motion started once pain subsides. Toe touch weight bearing is allowed initially with full weight bearing only with good clinical and radiological evidence of progressive fracture healing. In multiply injured patients the protocol was adapted to treat the associated injuries. Long term results were evaluated by modifying the Neers rating system. [12]
TABLE 2 :
Age and sex distribution of casesSex Age Male Female %
21-30 2 12.5 31-40 4 25 41-50 6 37.5
51-60 3 1 25
TABLE 3 :
Mechanism of injuryMechanism of injury No. of cases % RTA 13 81.2 Assault 2 12.5 Fall 1 6.2
TABLE 4 :
Relation between age of patient and cause of fractureAge RTA Fall Assault < 50 11 2 > 50 2 1
TABLE 5 :
Injury surgery intervalInjury surgery interval No. of cases % 5-8 days 4 25 9-14 days 10 62.5 > 15 days 2 12.5
TABLE 6 :
Operative timeTime No. of cases % < 90 mins. 14 87.5 > 90 mins. 2 12.5
TABLE 7 :
Period of radiological unionPeriod in weeks No. of cases % 14-18 9 56.25 19-23 6 37.5 24-28 1 6.25
OBSERVATIONS AND RESULTS
A total number of 16 patients were operated upon. Mean age of patients was 37 years (Table 2). The youngest case was 25 years old male and the oldest was 60 years old male. 81.25% cases13 were due to road traffic accident (Table 3). Most of the cases involved in high velocity accident were in the 31 to 50 years age group (Table 4). There were 11 closed fracture while remaining five were grade I open (Gustilo Anderson classification). Maximum number of fractures11 occurred in the diaphyseal segment, while three in the distal tibia and two in the proximal tibia as classified by the AO group. There was no case with intra-articular extension. Seven cases had associated injury resulting from the same trauma. The injuries noted were fracture of radius ulna, Hoffas fracture, fracture ribs, fracture pubic rami, contra-lateral fracture tibia. There were two cases with head injury.
The average injury surgery interval was 10.75 days with 62% cases operated in the period of 9-14 days injury (Table 5). The average operative time was 98 minutes (Table 6). Operative time reduced as experience was gained during the study. Healing of the fracture occurred with formation of callus.13 All fractures went to union. 62.5% cases showed union between 14 and 18 weeks, while 37.5% showed union between 19 and 23 weeks (Table 7). Average period of union was 17.63 weeks. Average time taken for full weight bearing was 19.6 weeks (Table 8). It was more for cases with bilateral limb injuries. 82% cases achieved full weight bearing by 23 weeks. Average period for hospital stay was 20 days. There was a single complication in the form of superficial infection secondary to skin necrosis treated with local debridement and antibiotics. There was no case of delayed union, non-union, implant failure or any significant deformity.
Long-term final results were rated using point system for pain, function, work ability, joint movement, and radiological and gross appearance. 93.75% cases14 had excellent to good outcome (Table 9). No case required bone grafting.
Rating was correlated to AO classification (Table 10).
DISCUSSION
The management of complex multifragmentary fractures has continually been a problem for the orthopaedic surgeons. They have been treated by conservative methods earlier in the form of casts or traction but poor results with regard to joint motion and prolonged recumbency were the problems. Closed methods have also been condemned for the treatment of bilateral extremity fractures and in the multiply injured person. [14] , [15]
Conventional plating in which the fragments of the broken bone were put together like doing the jigsaw, irrespective of the soft tissue attachments also led to a lot of problems like non union, delayed union, increased chances of implant failure, etc. With view of this biological plating techniques were introduced for treating such fractures. Interlocking nailing is also an established method in the treatment of comminuted diaphyseal fractures. Extended indications also cover the proximal and distal metaphyseal fragments. Minimally invasive plate osteosyntheses is on the contrary the treatment of choice in periarticular multifragmentary fractures. No special instrumentation is required. It can be used in the transition zone fractures where interlocking nailing is very demanding.
TABLE 8:
Time at which full weight bearing achievedPeriod in weeks No. of cases % 14-18 7 43.8 19-23 6 37.5 24-28 3 18.7
TABLE 8:
Time at which full weight bearing achievedPeriod in weeks No. of cases % 14-18 7 43.8 19-23 6 37.5 24-28 3 18.7
TABLE 9:
Functional outcomeRating No. of cases % Excellent 9 56.25 Good 6 37.5 Fair 1 6.2 Poor 0 0
TABLE 10 :
Rating as per the AO classificationExcellent Good Fair Poor Tibia fibula proximal (41) : A3 1 1 Tibia fibula diaphysis (42) : B2 1 1 B3 4 C1 2 C2 1 C3 1 Tibia fibula distal (43) : A3 1 2
n the present study, all fractures went to union. 93.75% of cases showed excellent to good outcome with the time to full weight bearing union averaging 17.63 weeks. The disparity between the period for full weight bearing and the period of union being mainly because of the presence of other associated injuries which delayed mobilization.
Helfet et al 16 in their study of distal tibial fractures treated with MIPO had no loss of fixation or evidence of hardware failure. There were isolated cases of delayed union, deformity and superficial cellulitis. All 20 cases showed union.
Radziejowski et al [17] in their study of 22 cases of proximal tibial fractures have also shown good results with union occurring in 12 to 24 weeks.
Johner and Wruhs18 reported a significant increase in complications as progressively higher energy fractures are treated with open reduction and conventional internal fixation. Complications increased from 9.5% for torsional to 48.3% for comminuted fractures. Likewise the infection rate increased from 2.3% for torsional fractures to 10.3% for comminuted fractures. Also nonunion was twice common and infection five times more likely when open fractures were treated with plating.
Vecsei et al19 presented their series of 158 fractures of the tibia-all long comminuted, treated with closed interlocked nailing. The complications observed were nail fracture (0.6%), infection (3.8%) and pseudoarthrosis (0.6%).
Klemm and Borner et al20 studied 401 complex tibial fractures treated with interlocked nailing. Overall 94.3% of them were judged to have an excellent or good results. Delayed union or non-union requiring bone grafts occurred in 0.7% of cases with deep infection developing in 2.2% cases.
Thus the results of the present short series in the treatment of high energy tibial fractures are better as compared to that for conventional plating techniques. Interlocked nailing is also an established method in the treatment of comminuted diaphyseal fractures with all the studies showing excellent to good results in majority of cases.
Minimally invasive plate osteosynthesis, on the contrary, is the treatment of choice in periarticular multifragmentary fractures. Equally good results as far as union and early mobilization are possible.
Advantages cited for MIPO are :
1.Simpler technique and easy to master. Learning curve short.
2.No need of additional expensive instrumentation.
3.Improved rates of fracture union.
4.Decreased infection rate.
5.Decreased need for bone grafting.
6.Ideal technique for dealing with the multiply injured patients.
7.Early mobilization of the extremity possible
8.Decreased incidence of refracture after plate removal.
No large series has been done to evaluate the MIPO technique for comminuted fractures. Hence, at present one cannot comment regarding its status as compared to interlock nailing. It needs further evaluation but the beginning is definitely encouraging. With longer follow-up and a larger number of patients, it seems that the minimally invasive technique of plate osteosynthesis for the treatment of multifragmentary fractures of the lower extremity will prove to be a feasible and worthwhile method of stabilization. It has been rightly said by well known anatomist R Schenk (1997), "If the fracture surgeon does something LOGICAL then BIO will do the rest". [1]
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