Contents
6.1 General Introduction 171
6.1.1 Technique of Indirect Reduction 171 6.1.2 Definition 171
6.1.3 Rationale 171
6.1.4 Fracture Healing Associated with Indirect Reduction 171 6.1.5 Preoperative Work-up 171
6.1.6 Commonly Used Instruments to Effect Indirect Fixation 172 6.2 Minimally Invasive Plate Osteosynthesis (MIPO) 172 6.2.1 Background Terminology 172
6.2.2 What Does MIPO Involve? 172 6.2.3 Traditional Concepts 172 6.2.4 Newer Developments 172 6.2.5 Latest Developments 173 6.2.6 Indication for MIPO 173
6.2.7 How Does MIPO Compare with IM Nailing and EF? 173 6.2.8 New Innovations of Plate Design and Technology to Complement
the MIPO Technique 173
6.2.9 What About the Argument that ºBlind Tunnelling Itself Causes Significant Soft Tissue Traumaº? 174
6.2.10 Virtual Fluoroscopy Vs. MIPO: Are They Complementary? 174 6.3 Minimally Invasive Surgery/MIPO in Different Body Regions 175 6.3.1 MIPO of Proximal Tibia 175
6.3.1.1 Cases of Tibial Fractures in Which to Consider MIPO 175 6.3.1.2 Problems of Fractures Around the Proximal Tibia 175 6.3.1.3 Common Surgical Approaches 175
6.3.1.4 Advantage of MIPO in Proximal Tibial Fractures 176 6.3.1.5 The Case for Adjunctive Fibular Fixation 176 6.3.1.6 The Spanning of the Plate 176
6.3.1.7 Disadvantages of a Lateral LISS Plate 176 6.3.1.8 Advantage of the Medial Approach 176 6.3.2 Distal Femur MIPO 177
6.3.2.1 Disadvantages of the Traditional AO Technique 177
6.3.2.2 Development of the MIPO Technique for the Distal Femur 177 6.3.3 Minimally Invasive Reduction of the Fractured Proximal Humerus 177 6.3.3.1 Indications 177
Minimal Invasive
and Computer-Aided Surgery 6
6.3.3.2 Advantages of the Minimally Invasive Technique 178 6.3.4 Minimally Invasive Technique for Articular Fractures
of the Distal Radius 178
6.3.4.1 Work-up of Complex Intra-Articular Fractures 178 6.3.4.2 Indication for Minimally Invasive Techniques 178 6.3.4.3 Methods of Reduction of Articular Fractures 178
6.3.4.4 Columnar Classification and Development of Fracture-Specific Implants 179
6.4 Computer-Aided Orthopaedic Surgery and Surgical Navigation 179 6.4.1 CT-Based Navigation 179
6.4.1.1 Advantages 179 6.4.1.2 Disadvantages 179
6.4.2 Virtual Fluoroscopy: Computer-Aided Fluoroscopic Navigation 179 6.4.2.1 Introduction 179
6.4.2.2 Advantages 180
6.4.2.3 Advantages of Virtual Fluoroscopy 180 6.4.2.4 Disadvantages 181
6.4.2.5 Summary of Comparison Between CT-Guided Navigation and Virtual Fluoroscopy 181
6.4.2.6 Clinical Example: Virtual Fluoroscopy in Long Bone Nailing 181
6.1 General Introduction
6.1.1 Technique of Indirect Reduction
n It is essential to note that indirect reduction techniques of fractures have to be mastered
n This is because many MIPO techniques described are based on indi- rect reduction
6.1.2 Definition
n Indirect reduction refers to a technique that avoids direct fracture ex- posure and further muscle stripping of the various small bone frag- ments in the fractured zone
6.1.3 Rationale
n It relies upon the technique of ligamentotaxis in which we restore the overall position of the fracture fragments, thereby avoiding periosteal stripping and devascularisation
n By protecting the viability of the fracture fragments, it may obviate the need for a subsequent bone graft and may result in a lower infec- tion rate
n We do need, however, to restore mechanical alignment, but not abso- lute anatomical alignment for these meta-diaphyseal fractures
6.1.4 Fracture Healing Associated with Indirect Reduction
n Unlike the traditional AO concept of absolute stability, which is now still valid for intra-articular fractures, with indirect reduction, the re- sult is relative stability as evidenced by callus formation
6.1.5 Preoperative Work-up
n Evaluate the fracture configuration
n Utilise implant templates
n Plan the method of fixation construct
n Step-wise approach of surgical tactics with which to approach the fracture
n The details can be found in the book written by Dr J Mast published by Springer
a 6.1 General Introduction 171
6.1.6 Commonly Used Instruments to Effect Indirect Fixation
n Universal distractor
n Articulated tensioner
n Laminar spreader
n Dental pick
n Clamps
n Weber's clamp
6.2 Minimally Invasive Plate Osteosynthesis 6.2.1 Background Terminology (Krettek)
n MIPO: minimally invasive plate osteosynthesis
n MIPPO: minimally invasive percutaneous plate osteosynthesis (for ex- tra-articular fractures)
n TARPO: trans-articular approach with percutaneous plating for intra- articular fractures
6.2.2 What Doe MIPO Involve?
n MIPO by definition avoids direct exposure of the fracture site. If used with a conventional plate, the plate is used as an extra-medullary splint, and thus does not depend on compression or lag screw appli- cation
n Since the conventional plates may not be ideally suited to MIPO, new, recently developed plates are now used to complement this technol- ogy, e.g. LISS plating
6.2.3 Traditional Concepts
n Traditional AO concept of open reduction and rigid IF resulting in di- rect bone healing
n Over-emphasis on mechanics at the expense of biology, although All- gower did advocate ªcare in soft tissue handlingº
6.2.4 Newer Developments
n Mast came up with the concept of ªindirect reductionº
n The principle is to take advantage of the soft tissue connection of the bone fragments, which align spontaneously when traction is applied to the main fragments
n Advantage: reduce surgical dissection, less compromise of vascularity, thus possibly better healing and less sepsis
6.2.5 Latest Developments
n New insight: observation that IF is based purely on reduction of frag- ment mobility without the bone fragments touching may also result in solid bone healing
n Result = principle of absolute stability by interfragmentary compres- sion replaced (at least in the situation of many meta-diaphyseal frac- tures) by the principle of ªpure internal splintingº
n Ganz coined the term ªbiological fixationº 6.2.6 Indication for MIPO
n Best indicated for situations in which biology is the most important concern (e.g. in the face of significant soft tissue trauma)
n Although it is still possible to perform minimally invasive plating using conventional plates, the newer point contact fixators and the lat- est LCP that do not require pre-contouring (together with self-drilling and self-tapping screws) are the best adjunct to go with the MIPO technique
6.2.7 How Does MIPO Compare with IM Nailing and EF?
n Although IM nailing permits a minimal open approach, the advan- tages are offset by the extensive damage to the intramedullary circula- tion, and local and general intravascular thrombosis
n Although the EF preserves biology of the fracture fragments, healing is slow and sometimes delayed at the expense of patient comfort 6.2.8 New Innovations of Plate Design and Technology
to Complement the MIPO Technique
n Special design help in the tunnelling of the new plate systems such as LISS and LCP
n Examples:
± The end of the LISS plate is pointed
± The LISS (Fig. 6.1), which is mostly used to fix metaphyseal or meta-diaphyseal fractures, is pre-contoured to fit the anatomy of most femurs and tibiae
a 6.2 Minimally Invasive Plate Osteosynthesis 173
± The aiming handle helps insertion and screw insertion since the locked unicortical screws require alignment of the implant and the bone axis within comparably narrow limits
± Screws are self-drilling and self-tapping to minimise the difficulty in finding the initial drill hole, and the added steps of measuring and tapping of conventional plating
6.2.9 What About the Argument that ªBlind Tunnelling Itself Causes Significant Soft Tissue Traumaº?
n Previous studies carried out by Krettek and others regarding the ef- fect of the ligation of the perforating arteries, for example, during the open surgical approach to femoral fractures, has disproved the argu- ment
6.2.10 Virtual Fluoroscopy Vs. MIPO: Are They Complementary?
n This is affirmative
n Example is shown in the setting of the LISS:
± In LISS plating, the distal fragment of the fracture comes under the direct vision of the operating surgeon. However, one intra- operative challenge for the surgeon is that the proximal fragment must be accurately reduced and fixed properly to the LISS as ec- centric plate placement causes early pull-out of the monocortical screws
n This requires the surgeon to control six degrees of freedom at the same time. But a single fluoroscopic image provides information only
Fig. 6.1. The LISS plate was de- signed for the MIPO technique
on three degrees of freedom. It is difficult for the surgeon to maintain length, fracture alignment, and fracture rotation using imaging in only one plane at a time
n Virtual fluoroscopy allows the plate and proximal fragment to be tracked independently in > two planes, during reduction of the fracture
n In future, implant-specific software may come of age to aid the trau- ma surgeon in obtaining adequate proper images, allowing accurate restoration of length, alignment and rotation, especially during mini- mally invasive plate osteosynthesis
6.3 Minimally Invasive Surgery/MIPO in Different Body Regions
6.3.1 MIPO of Proximal Tibia
n One common problem with fixation of proximal tibial fractures arises from soft tissue complications, say, after ORIF with traditional plat- ing. The MIPO technique can help in this respect
6.3.1.1 Cases of Tibial Fractures in Which to Consider MIPO
n Metaphyseal or combined metaphyseal-articular fractures of the prox- imal tibia
6.3.1.2 Problems of Fractures Around the Proximal Tibia
n Difficult to reduce
n Difficult to align
n Difficult to stabilise
n Easy to develop soft tissue and wound Cx
n Infections
6.3.1.3 Common Surgical Approaches
n Medial
n Lateral
n Combined
n Main advantage of medial approach as opposed to lateral approach is that plate can be subcutaneous instead of submuscular, and has been used by Krettek successfully ± especially if the main pathology is on the medial side
a 6.3 Minimally Invasive Surgery/MIPO in Different Body Regions 175
(P.S. to visualise any articular component of the fracture, we may need to extend the incision to allow for a submeniscal arthrotomy. We perform MIPO only after articular reconstruction)
6.3.1.4 Advantage of MIPO in Proximal Tibial Fractures
n Allows for stabilisation of both medial and lateral columns through a single approach, if used with the newer locking plates, which provide angular stability
n Many of the locking plates for the proximal tibia are designed for the lateral proximal tibia (e.g. LISS-PT) and are to be used in conjunction with a lateral approach for submuscular tunnelling beneath the tibialis anterior
n Krettek emphasised that certain injuries are best treated with subcuta- neous medial plating if the main pathology is on the medial side, or occasionally if the soft tissues on the lateral side are greatly trauma- tised
6.3.1.5 The Case for Adjunctive Fibula Fixation
n To obtain a lateral weight-bearing strut
n Offers a fulcrum when fine tuning the tibial alignment prior to fixa- tion of the main distal tibial fragment
n Correction of length
6.3.1.6 The Spanning of the Plate
n The plate should bridge the metaphyseal±diaphyseal fracture frag- ment, extending distally from the level of the joint, so that at least three bicortical diaphyseal screws can be used for distal fixation 6.3.1.7 Disadvantages of a Lateral LISS Plate
n Do need to elevate muscle with some unavoidable devitalisation of the fracture
n Risk of peroneal nerve injury especially when a 13-hole LISS was used
n Risk of compartment syndrome
6.3.1.8 Advantages of the Medial Approach
n Allows fixation of the bicondylar fracture through a single incision
n No muscle stripping
n Especially useful if mostly medial comminution or in the presence of traumatised lateral soft tissue, and/or if the compartment pressure is increased
6.3.2 Distal Femur MIPO
6.3.2.1 Disadvantages of the Traditional AO Technique
n Decreases bone perfusion beneath the plate
n Decreased rate of fracture vascularisation
n Increased susceptibility to infection
6.3.2.2 Development of the MIPO Technique for the Distal Femur
n The idea is mainly to decrease surgical dissection, again working on the principles of ligamentotaxis
n The feasibility of performing MIPO techniques for the distal femur was reinforced thanks to previous cadaveric studies performed by Krettek
n The AO LISS plating system was well suited for the performance of the MIPO technique in the region of the distal femur, the details of which have already been discussed in Chap. 4 and also in the section on fractured distal femurs in Chap. 8
6.3.3 Minimally Invasive Reduction of Fractured Proximal Humerus 6.3.3.1 Indications
n Can usually only be considered in the presence of soft tissue bridging of the fracture fragments in order to gain benefit from ligamentotaxis
n Recent work of Hertel et al. shows that the vascularity of the humeral head is more likely to be maintained if:
± There is an intact medial hinge of soft tissues
± Alengthy metaphyseal head extension is noted on analysing the fracture pattern
n Common indications:
± Valgus impacted fractured proximal humerus
± Three-part fractures
a 6.3 Minimally Invasive Surgery/MIPO in Different Body Regions 177
6.3.3.2 Advantages of the Minimally Invasive Technique
n In the absence of fracture exposure, adhesion within the surrounding gliding surfaces is reduced and the rehabilitation period possibly shorter than with open surgery. More detailed discussion can be found in Chap. 7
n Less chance of sepsis
n Less bleeding
n Probably less pain and quicker rehabilitation
6.3.4 Minimally Invasive Technique for Articular Fractures of the Distal Radius
6.3.4.1 Work-up of Complex Intra-Articular Fractures
n CT scanning is of help for the surgical planning of the fixation of dis- placed intra-articular fractures
n The wrist joint has low tolerance for articular incongruity and careful preoperative planning is essential
6.3.4.2 Indication for Minimally Invasive Techniques
n Minimal invasive techniques should be considered if close reduction fails
n For those cases in which closed reduction is successful, a combination of EF and multiple K-wires can be used to provide maintenance of re- duction (although large fragments are best held by plates and screws) 6.3.4.3 Methods of Reduction of Articular Fractures
n It was shown by Jupiter that a 2-mm articular step off is predictive of post-traumatic arthrosis and poor functional result. Avascular necro- sis (AVN) is rare in intra-articular distal radius fractures because of the good blood supply, but it can occur in high energy injuries
n The methods of reduction include:
± Open reduction using standard incisions (involves more soft tissue dissection)
± Smaller incisions now rendered possible thanks to the development of new low profile, fracture-specific implant for intra-articular frac- tures of the distal radius
± Mini-open reduction (sometimes mini-incisions for the purpose of
± BG)Arthroscopic-assisted reduction ± gaining popularity
6.3.4.4 Columnar Classification and Development of Fracture-Specific Implants
n The columnar classification is an increasingly popular classification for intra-articular fractures of the distal radius. The distal radius in this classification is divided into the lateral or radial column, the in- termediate column, and the medial or ulna column. New low-profile plating systems have now been developed to tackle each of the col- umns. For example, if only the dorsal ulna corner is fractured, we need only use the corresponding plate to tackle the fracture and mini- mise soft tissue dissection and surgical trauma
(Further discussion on this topic will be found in Chap. 7)
6.4 Computer-Aided Orthopaedic Surgery and Surgical Navigation
6.4.1 CT-Based Navigation
n This method involves:
± The need for preoperative CT
± Aregistration step: whereby to relate a 3D virtual model to an ac- tual object in the theatre
6.4.1.1 Advantages
n Decreased operative time
n Decreased radiation exposure 6.4.1.2 Disadvantages
n Requires preoperative CT ± thus not suitable for fracture cases in which reduction will be performed after CT is obtained
n Need for a registration step
n Cost
6.4.2 Virtual Fluoroscopy:
Computer-Aided Fluoroscopic Navigation 6.4.2.1 Introduction
n Involves:
± Tracking the position of the patient and fluoroscopic unit by opto- electronic and electromagnetic markers
a 6.4 Computer-Aided Orthopaedic Surgery and Surgical Navigation 179
± Storage and harvesting of 2D C-arm X-ray images in the OR
± Use of the stored images for surgical navigation by displaying the position of optically-tracked instruments with respect to the images
± The images can be readily updated (e.g. post-reduction manoeu- vres)
± Virtual fluoroscopy displays the predicted position of surgical in- struments and implants relative to stored images. These systems have an inherent error of <2 mm or <28
n After, say, fitting of optical tracking arrays (e.g. via use of light emit- ting diodes) to both the C-arm and the patient to allow tracking of the fracture, the calibration target and a software package are used to warp each X-ray image to render them optically correct
n Interface with a computer-aided orthopaedic surgery (CAOS) worksta- tion and computer
n After storing the images, the real-time position of surgical instru- ments can be overlaid upon stored images
n Real-time feedback possible as the instruments are moved 6.4.2.2 Advantages
n Allows the trauma surgeon to update images in the operating room after fracture reduction and use the updated image for surgical navi- gation
n No need for preoperative CT
n Scope of orthopaedic surgery suitable for this technique is much wider than that for CT-based technology. CT-based technology is now being replaced in some centres by virtual fluoroscopy
6.4.2.3 Advantages of Virtual Fluoroscopy
n Apreoperative 3D model is not necessary
n Involves storage and harvesting of 2D C-arm fluoroscopic images in the operating room
n Electromagnetic or opto-electronic markers are used to mark the po- sition of patients and the fluoroscopic unit
n Stored images are employed to provide surgical guidance and can be readily updated after, say, fracture reduction performed
6.4.2.4 Disadvantages
n Cost
n Has an inherent error as reported by the system manufacturer
n The system does not have the capability to track an implant once it is inserted into bone; thus, errors in screw positioning may occur, for example in the event of guide-wire deflection
6.4.2.5 Summary of Comparison Between CT-Guided Navigation and Virtual Fluoroscopy
n 3D CT-based CAOS systems are not suitable for aiding the three criti- cal steps of, say, the femoral nailing procedure. The technique also re- quires preoperative CT and not is suitable for fracture cases in which a reduction will need be performed after obtaining the CT
n However, with the advent of virtual fluoroscopic techniques, surgical navigation of these three critical steps can be performed
n This new technique decreases the amount of ionising radiation to which the orthopaedist is exposed. The disadvantage is the expense in procuring specialised equipment and instruments
6.4.2.6 Clinical Example: Virtual Fluoroscopy in Long Bone Nailing
n In search of the proper insertion site for the IM nail: the starting point (for nail insertion) can be identified by virtual fluoroscopy. The trajectory ªlook-aheadº feature can be used to align the drill guide with the femoral canal in two planes; the guide wire is then inserted into the piriform fossa. Overdrilling and reaming then follows
n Fracture reduction: a special reduction rod with an array of light emitting diodes can be inserted into the proximal fragment and nego- tiated to the fracture via virtual fluoroscopy. Fracture manipulation follows until the virtual axis of the proximal fragment aligns with the distal fracture fragment
(Anew femoral fracture reduction software package that is said to be able to obtain accurate reduction in sagittal and coronal planes, and restoration of anteversion will soon become available. With this tech- nology, both fracture fragments are instrumented and tracked. Dock- ing points will match up when the fracture is reduced)
n Placement of locking screws (Fig. 6.2, 6.3):
a 6.4 Computer-Aided Orthopaedic Surgery and Surgical Navigation 181
± The technique can aid in the controlled insertion of the proximal screws in cephalomedullary nailing as well as confirming the ver- sion and depth of nail insertion
± Virtual depth gauge for the selection of proper screw length of dis- tal interlocking screws is possible thanks to the trajectory length feature of this new technology
General Bibliography
International Commission on Radiological Protection, Publication 60. Recommenda- tions of the International Commission on Radiological Protection
Fig. 6.2. Virtual fluoroscopy in action
Fig. 6.3. Use of virtual fluoroscopy as an aid to locking bolt insertion in IM nailing
Selected Bibliography of Journal Articles
1. Foley KT, Simon DAet al. (2000) Virtual fluoroscopy. Oper Tech Orthop 10:77±81 2. Simon DA, O'Toole RV et al. (1995) Accuracy validation in image-guided orthopae-
dic surgery. Proceedings of the 2nd International Symposium on Medical Robotics and Computer-Assisted Surgery
3. Rampersaud YR, Foley KT et al. (2000) Radiation exposures to the spine surgeon during fluoroscopically assisted pedicle screw insertion. Spine 25:2637±2645 4. Helfet DL, Shonnard PY et al. (1997) Minimally invasive plate osteosynthesis of dis-
tal fractures of the tibia. Injury 28 [S-A]:42±48
a Selected Bibliography of Journal Articles 183
