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Submuscular plating of the distalfemur
SUBMUSCULAR PLATING OF THE DISTAL FEMUR PHILIP JAMES KREGOR, MD, MICHAEL ZLOWODZKI, MD, JAMES STANNARD, MD, and PETER ALEXANDER COLE, MD
A va:¢iety of implants are available for the treatment of distal femur fractures. However, continued problems include infecl~on, nonunion, need for bone grafting, malunions, joint stiffness, and loss of fixation. "Biological plating" emphasizes maintenance of the soft tissue environment around the fracture. The concept of "biological plating" in supracondylar femur fractures has been very advantageous. The Less Invasive Stabilization System (LISS) for fractures of the distal femur combines these biological advantages of submuscular fixation with the biomechanical advantage of fixed angled, locked screws for fixation of the distal femoral block. The LISS may be particular helpful in the setting of complex articular pathology, a short distal segment, and osteoporotic bone. LISS methodology relies on traditional internal fixation of the articular surface, closed reduction of metaphyseal/diaphyseal component of the fracture, and placement of a submuscular LISS fixator. Percutaneous locking screws are then placed for proximal fixation. In this review, the evolution of submuscular fixation of supracondylar femur fractures and the technique are described. KEY WORDS: aupracendylar, femur, submuscular, plate, fixation © 2003 Elsevier Inc. All rights reserved.
Distal femur fractures continue to be problematic for the clinician. Emphasis on internal fixation for supracondylarintercondylar femur fractures over the past three decades has improved the outcome from these injuries. 1-9 However, continued problems include infection, nonunion, need for bone graft'mg, malunions, joint stiffness, and loss of fixation. 1-6,845 "Biological plating," as popularized b y Mast, Jakob, and Ganz, emphasizes maintenance of the soft tissue environment around the fracture. ~6,17Its tenets include restoration of length, rotation, and alignment-without the need for precise anatomic restoration of every cortical fragment. "Leaving the fragments alone" results in a more predictable ,and more expedient fracture consolidation in these areas. Its advantages have been seen in subtrochanteric femur fractures, ~8 femoral shaft fractures, 19 tibial shaft fractures 2°, and pilon fractures. 21 The concept of "biological plating" in supracondylar femur fractures has also been very advantageous. Bolhofner and co-workers reported on 57 cases of supracondylar femur fractures treated with biological plating techniques utilizing the condylar blade plate or condylar buttress plate. 9 In this series, emphasis was placed on allowing the implant, after being connecte:d to the distal femoral block, to aid in reduction of the fracture. In a series in which no bone grafting was utilized, time to radiographic union and full From the Division of Orthopedic Trauma, Vanderbilt University Medical Center, Nashville, TN, USA; Division of Orthopedic Surgery, University of Alabama Medical Center, Birmingham, AL, USA; Regions Hospital, University of Minnesota, St. Paul, MN, USA. Address reprint requests to Philip James Kregor, MD, 2100 Pierce Avenue, 131 Medical Center South, Nashville, TN, 37232. E-mail: philip.kregor @vanderbilt.edu. © 2003 Elsevier Inc. All rights reserved, 1048-6666/03/1302-0000530.00/0 doi:l 0.1053/otor.2003.0168
Operative Techniques in Orthopaedics, Vol 13, No 2 (April), 2003: pp 85-95
weight bearing was 10.7 weeks. There were 2 delayed unions, but no persistent nonunions. This is in sharp contrast to series involving traditional open reduction/internal fixation. 1-4,1° Miclau and co-workers noted bone grafting rates ranging between 0 to 87% with traditional internal fixation. 8 "Biological plating" for supracondylar femur fractures gradually evolved into submuscular plating. Krettek and co-workers described the use of a dynamic condylar screw placed in a submuscular martrter. 22-24 In this method, the articular surface is reduced after appropriate visualization, and internal fixation of the articular surface is then performed. It should be emphasized that nothing is "new" with regards to reduction and fixation of the articular surface. The articular injury must have an appropriate preoperative assessment, adequate surgical exposure, exact repositioning/reduction, and stable fixation. It is only after the articular reduction is accomplished that the submuscular method may be utilized to address the metaphyseal/diaphyseal component of the fracture. Thus, the surgeon should not compromise the articular surface exposure or reduction because submuscular methods are utilized. The premise of submuscular sliding of a plate along the femoral shaft is based on the naturally existing potential space between the undersurface of the vastus lateralis and the periosteum of the femoral shaft. The surgeon can exploit this space by passing the plate along the femoral shaft. A natural concern would potentially be increased vascular damage to the femoral shaft by injuring perforating vessels. This has not been the case, as demonstrated experimentally. Vascular injection dye studies have demonstrated that submuscular plate application disrupts the femoral blood supply less in 70% of specimens when 85
comparing it to the contralateral side with traditional plate osteosynthesis. 25 Although submuscular plating preserves the vascularity around the fracture, reduction difficulties remain, or are even greater. Malreductions of the distal femur are probably under-recognized. Zehntner and co-workers reported on an intermediate follow-up (5 years 7 months average) of 57 supracondylar femur fractures treated with traditional plating techniques by experienced surgeons and found varus/valgus malreductions greater than 5 ° in 26% of cases. 26 In addition, sagittal plane deformities (apex anterior or posterior) were seen in 22%, and rotational deformities in 17%. With indirect, submuscular plating techniques, malalignment can be even more problematic. Krettek and co-workers reported on 8 supracondylar-intracondylar femur fractures (AO/OTA classification C2C3) treated with submuscular plate fixation and noted 2 varus/valgus deformities greater than 5 °, 2 leg length discrepancies greater than 10 mm, and two rotational deformities of 15°. 22 Thus, if the surgeon wishes to gain the advantages of submuscular fixation, surgical strategies must be developed to minimize malalignment problems. In addition to reduction difficulties, varus collapse of the distal femoral block continues to be problematic. Distal fixation is critical especially in osteoporotic bone. In the past decade, this problem has been addressed via double plating of the distal f e m u r , 27 medial external fixator placement, and placement of a diagonal distal femoral screw. 28 Recently, "locked" plating has become available. 29,3° In locked plates, screws have a threaded screw head which then threads into a recipient threaded screw hole in the plate. A locked plate can best be thought of as an "internal fixator." As with an external fixator, principles include: 1. Classic articular reduction and fixation, 2. "Spanning" the zone of comminution in the diaphyseal/metaphyseal area of the fracture, and 3. Utilization of a longer "construct" than with normal plating. In an effort to combine the biological advantages of submuscular plating and the biomechanical advantages of fixed-angled or "locked" plating, the Less Invasive Stabilization System (LISS) was developed (Fig 1). Its characteristics include: 1. Multiple, fixed angled screws which lock into the distal end of the fixator, and 2. An insertion handle that allows for submuscular sliding of the fixator and for placement of percutaneous, self-drilling, unicortical screws for fixation of the diaphyseal component of the fractures. Biomechanical testing has shown that a blade plate/femur construct and a retrograde I M N / f e m u r construct often results in loss of distal fixation, while a LISS/femur construct maintains fixation of the implant at higher loads. 31 The load to failure in one-time axial loading is significantly higher when using a LISS in comparison to a blade plate. It is the purpose of this paper to outline the surgical indications, surgical technique, and complications associated with its use. Case examples will be used to illustrate its use. Secondary surgical procedure rates after primary
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fixation with commonly used devices such as a blade plate, retrograde nail, dynamic condylar screw, or external fixation are reported between 0% and 25.7% (Table 1). It should be understood that while the LISS is a specific device, the two basic features of allowing submuscular fixation and fixed angled screw fixation are its key characteristics. As with all fracture surgery, it is the surgical technique that is more important than the actual implant. Submuscular fixation can also be performed with standard dynamic condylar screw plates, and newer locking condylar buttress plates.
SURGICAL INDICATIONS Supracondylar femur fractures are best classified via the A O / O T A Classification (Fig 2). 32 For A-type (nonarticular supracondylar femur fractures) and C1/C2 (supracondylar femur fractures with simple articular splits), a variety of implants have proved efficacy: 95 ° Dynamic Condylar Screw, 33 95 ° Condylar Blade Plate, 1-3,7,9A°,34Retrograde Supracondylar Nail, 11-13,35-37 and Antegrade Intramedullary Nailing. 38 Thus, the LISS may not add a distinct advantage in all cases. There are situations, however, where the LISS may offer particular benefit: 1. Treatment of a supracondylar femur fracture with a very short distal segment, especially in the setting of osteoporosis. In such a situation, fixation of the distal femoral block with an intramedullary nail may be difficult and problematic (Fig 3). 2. Treatment of supracondylar femur fractures above total knee arthroplasty, especially when the distal femoral block is short a n d / o r osteoporotic. 3. Treatment of the high-energy C3 distal femur fracture. 39 The C3 distal femur frac~re remains a difficult surgical challenge because of several factors: 1. Adequate exposure of articular surface, especially of the medial femoral condyle, is challenging without large surgical exposure a n d / o r tibial tubercle osteotomy,
2. Standard implants utilized for other supracondylar femur fractures (eg, condylar blade plate and retrograde nails) may jeopardize the articular surface reduction and fixation, 3. Especially in the setting of a short distal segment, varus collapse, a n d / o r loss of fixation of the distal femoral block can occur.
INITIAL S T A B I L I Z A T I O N A N D P A T I E N T ASSESSMENT After appropriate history and physical examination, provisional stabilization of the femur fracture may be addressed by utilizing a long-leg splint placed while the leg is held in manual distal traction. As with most closed reduction of fractures, an emphasis is placed on early intervention. After stabilization of life-threatening injuries, the supracondylar femur fracture may be addressed. Surgical stabilization should proceed with an adequate understanding of the fracture, an appropriate surgical team,
KREGORET AL
D
;i
Fig 1. (a) The LISS consists of an anatomically shaped, precontoured fixator with an accompanying outrigger device which allows for submuscuiar fixator application. (b,c) The screws placed through drill sleeves are self-drilling and self-tapping. They can be placed percutaneously, and are locked into the fixator, thus acting as "mini-blade plates" in the distal femoral block. (c) After traditional internal fixation of the articular surface, the mataphyseal/diaphyseal component of the fracture is "spanned" with the LIISS internal fixator. SUBMUSCULAR PLATING OF THE DISTAL FEMUR
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T A B L E 1. Nonunion and Infection Rates in Treatment of Supracondylar Femur Fractures in the Literature n
Year
Implant/Technique
Nonunion Rate*
Infection Rate
Schatzker et al (2) Sanders et al (27) Merchan et al (41) Shewring et al (42) Lucas et al (43) lannacone et al (36) Bolhofner et al (9) Marsh et al (44)
35 9 42 21 25 41 57 13
1979 1991 1992 1992 1993 1994 1996 1997
Mostly blade plate Double Plating Blade Plate DCS Retrograde IMN Retrograde IMN Blade Plate or CBP/Indirect Reduction External Fixation
25.7% 0% 7.1% 9.5% 16% 19.5% 0% 0%
Hutson et al (45) Kregor et al (46) Schuetz et al (47)
16 66 99
2000 2001 2001
Limited Internal Fixation + ExFix LISS LISS
12.5% 5% 9%
0% 0% 7.1% 0% 4% 0% 1.8% 7.7% 18.8% (1/3 Pin) 3% 7%
*Includes secondary surgical procedures for delayed unions.
and a stabilized patient. If these conditions are not met, especially in the setting of high-energy, highly displaced fractures, a spanning external fixator is an excellent temporary device which stabilizes the limb, maintains length of the extremity, and minimizes fracture motion contributing to further soft tissue swelling. Pins of the external fixator placed at a significant distance from the knee joint (eg, proximal femur and distal tibial) will not contaminate the future operative site for the supracondylar femur fracture. Excellent quality AP, lateral and oblique radiographs are mandatory before preoperative planning for stabilization of the fracture. Poor quality anterior-posterior (AP) and lateral radiographs, especially in the shortened leg, often do not delineate significant articular pathology. Oblique radiographs are necessary to better delineate the intercondylar pathology because the patella often obscures the intercondylar fracture. In cases of complex multiplane fractures, axial computerized tomography (CT), with frontal and sagittal plane reconstructions may be helpful in planning the surgical stabilization.
SURGICAL TECHNIQUE Patient Positioning
The leg length and rotational profile of the contralateral extremity, if possible, is examined preoperatively to ascertain the correct length and rotational profile of the distal femur. A towel bump is then placed under the ipsilateral buttock to counteract the normal external rotation of the lower extremity. If the pelvis is tilted up approximately 15° on the involved side, and the rotational profile of the injured femur is correctly reestablished, the foot will be 5 to 10° externally rotated in most cases at the end of the case. This is a helpful check to avoid serious rotational mismatches. Operative intervention is best performed on a completely radiolucent table, which allows complete imaging of the lower leg. Appropriate padding under the uninvolved extremity is placed, and the uninvolved extremity is secured in place. Prep and drape should allow for complete exposure of the proximal femur and hip region, especially if a longer fixator is to be utilized. 88
Fig 2. The AO/OTA classification for supracondylar/intercondylar femur fractures is helpful to delineate surgical approach and implant choice. "A" fractures are extra-articular, "B" fractures are isolated condylar fractures, and "C" fractures are intraarticular. A "C3" fracture is differentiated from "C1/C2" fractures by its complex articular pathology. (From Hansen ST, Swiontkowski MF (eds): Orthopaedic Trauma Protocols. Raven Press, New York, 1993, p296; with permission.) KREGOR ET AL
Fig 3. (a) A 63 year old female sustained a C2 distal femur fracture, (b) immediate postoperative films. (c) Varus collapse of the distal femoral block resulting in destruction of the lateral femoral condyle, (d) Femoral condyles with articular surface destruction (arrow) of lateral femoral condyle (LFC) seen at time of revision surgery, SUBMUSCULAR PLATING OF THE DISTAL FEMUR 89
Surgical Approach Through a careful examination of the injury radiographs, the following questions should be answered: 1. Is there involvement of the articular surface? 2. If so, is the involvement simple or complex? Is the intercondylar fracture central in the patellar groove, or is it more medial? 3. Are there frontal plane ("Hoffa') fractures in either the medial or lateral femoral condyle? 4. Are there separate intercondylar notch osteochondral fragments? For nonarticular fractures (AO/OTA Classification A1A3) and fractures with simple articular involvement (AO/ OTA Classification C1 and C2), a standard anterolateral approach to the femur is performed, as described below. For multiplane articular involvement, medial-based intercondylar splits, "Hoffa" fractures, and separate intercondylar notch fragments, a lateral peripatellar approach is utilized. 4° A standard anterolateral approach to the distal femur is performed with the patient in the supine position. A curvilinear incision is utilized which begins approximately 3 to 6 cm proximal to the tibial tubercle and curves slightly anterior to the mid lateral aspect of the distal femur. For a nonarticular fracture, the incision utilized is approximately 6 cm, while for articular fractures, the incision is 8 to 10 cm. If articular visualization is necessary, the joint capsule may be divided in line with the split in the iliotibial band distal to the level of the lateral meniscus. A carefully placed Hohmann retractor on the medial aspect of the medial femoral condyle allows for visualization of the distal articular surface. The lateral peripatellar approach22, 24 allows excellent visualization of the entire articular surface, and it is particularly helpful in cases of multiplane articular involvement. The extensor retinaculum and mechanism is longitudinally divided in a curvilinear manner, leaving a cuff of tissue to the lateral aspect of the patella for later repair. The patella may be everted, affording visualization, reduction, and fixation of the articular surface. The LISS (or a submuscular plate) may then be inserted through the lateral peripatellar wound. Articular Fracture Reduction and Fixation
Reduction aids for the articular surface that may be helpful include: • Schantz pins utilized as joysticks in the medial and lateral femoral condyle which aid in reduction of the intercondylar fracture, • Large pointed reduction "Weber" clamps, or large pelvic reduction clamps, which compress the lateral and medial femoral condyle blocks together, • Provisional K-wires, which can hold reduction of articular blocks until definitive lag screw fixation is achieved, and • Dental picks, which are helpful in fine manipulation of articular segments. After reduction is achieved, multiple 3.5 mm cortical lag screws are utilized in a lateral to medial direction for fixation of intercondylar fractures, or in an anterior to 90
Fig 4. Intraoperative photo of supracondylar towel bump in position posterior to the supracondylar region, The LISS fixator has been slid in a submuscular manner and proximal percutaneous screws are being placed.
posterior direction for fixation of "Hoffa" fractures. Minifragment 2.7-ram lag screws are also utilized, especially for fixation of small osteochondral fragments in the intercondylar notch. After reduction and fixation of the articular surface is achieved, attention is then turned to reduction and fixation of the metaphyseal/diaphyseal component of the fractures.
Reduction aids for LISS Fixation of Distal Femoral Fractures The goal of LISS fixation is to maintain the soft tissue environment around the metaphyseal/diaphyseal component of the fracture. This is performed utilizing closed reduction techniques. A variety of "aids" are utilized which facilitate the closed reduction techniques. These include: 1. Early Intervention: As mentioned above, fractures are addressed as soon as possible. If high-energy, shattered fractures are not stabilized in the first 24 hours, a spanning external fixator is placed to maintain the length of the fractured extremity. 2. Chemical Paralysis: Complete clinical paralysis of the patient is necessary. 3. Supracondylar Towel Bumps: Supracondylar towel bumps of 10, 12, and 15 rolled surgical towels wrapped with an elastic bandage are utilized to be placed in the area posterior to the supracondylar region. The towel bumps aid in reduction of the common hyperextension of the distal femoral fragment (Fig 4). In addition, the bump acts as a fulcrum for the vector force of the manual traction pull. Relatively small adjustments in the size a n d / o r location of the towel bumps cam make large differences in sag!ttal plane correction of the fracture. 4. Manual Traction: Hard manual traction is helpful to establish length and rotation, and may facilitate varus/valgus correction. Manual traction is applied to the ankle region, and with a force vector that is directed posteriorly. Utilizing the towel bumps as afulcrum, the manual traction facilitates reduction of the hyperextension deformity of the distal femoral condyle. KREGOR ET AL
5. Distal F e m o r a l C o n d y l e Schantz Pin: Especially in cases of a v e r y short distal f e m o r a l segment, correction of the h y p e r e x t e n s i o n d e f o r m i t y m a y be difficult. This m a y be a i d e d b y an anterior to posterior Schantz pin, w h i c h m a y act as a "joystick" to derotate the distal f r a g m e n t into a p p r o p r i a t e reduction. 6. " W h i r l y b i r d " A p p r o x i m a t i n g Device: The "Whirlyb i r d " device is a self-drilling, self-tapping p i n that can be drilled into the f e m o r a l cortex, either in the distal or p r o x i m a l regions. A t u r n i n g n u t against the outrigger LISS insertion device will actually a p p r o x i m a t e the f e m o r a l cortex to the LISS fixator. The device m a y be, therefore, utilized to afford small corrections in v a r u s / valgus deformities. M o r e t h a n one " W h i r l y b i r d " device m a y be u s e d together to afford small translation corrections of the p r o x i m a l segment. P l a c e m e n t of the " W h i r l y b i r d " device can be likened to a c l a m p placer m e n t , as it will stabilize the reduction as the selfdrilling screws are inserted. 7. F e m o r a l Distractor or External Fixation: The f e m o r a l distractor or external fixator m a y be utilized to obtain a n d m a i n t a i n the m e t a p h y s e a l / d i a p h y s e a l reduction. H o w e v e r , its use m a y m a k e fine a d j u s t m e n t s in fracture r e d u c t i o n difficult. 8. M a n u a l P r e s s u r e : M a n u a l p r e s s u r e utilizing a large mallet is occasionally n e c e s s a r y to p u s h m e d i a l l y on an a d d u c t e d a n d / o r flexed p r o x i m a l f r a g m e n L In addition, it m a y be utilized on the distal f r a g m e n t to correct excess valgus.
SURGICAL SEQUENCE OF LISS FIXATION (FIG 5) Just a s w i t h p l a c e m e n t of a n y fixation device for distal f e m o r a l fractures, there is a well defined, stepwise process for LISS fixation of distal f e m o r a l fractures. A l t h o u g h there m a y b e variations on this sequence, it i s helpful t o a d d r e s s each step in the surgical sequence. The LISS fixation sequence begins after articular fracture r e d u c t i o n a n d fixation. Step 1: Provisional Fracture Reduction ("Learning the Fracture") Before the LISS fixator is inserted, manual traction is applied, the supracondylar bumps are placed, and the fracture reduction is visualized on both AP and lateral fluoroscopy. The surgeon can then note facts such as hyperextension of the distal femoral condyle, flexion and/or adducti0n of the proximal femoral shaft, and/or valgus of the distal femoral condyles. Adjustments in position and/or size of the supracondylar bumps,, vector force direction of m~nua! traction, and correction of deformities utilizing the large mallet can then be made. Although the insertion handle for the LISS is radiolucent, improved visualization of the fracture reduction is seen before LISS insertion. Step 2: LISS Insertion The LISS fixator is inserted through either the anterolateral incision or lateral peripatellar approach. The fixator is preshaped to account for the anterior bow of the femur. This step can be done under brief line fluoroscopy and is aided by: • The tactile sensation of the proximal tip of the fixator or the lateral cortex, and
SUBMUSCULARPLATINGOF THE DISTAL FEMUR
. Assessing the relationship of the insertion handle (ie, "outrigger device") with regards to the lateral aspect of the thigh. A common tendency is to direct the fixator posteriorly; this can be avoided by careful attention to the last step. Step 3: Connection of the Proximal Locking Sleeve Connecting Bolt Through an incision over either the # 9-hole or the # 13-hole, a proximal connecting bolt is screwed into the proximal end of the flxator. This creates a fixed parallelogram that facilitates further manipulation of the fixator on the mid lateral aspect of the femur. Step 4: Establishment of Appropriate Placement of LISS Fixator on Distal Femoral Condyle The LISS fixator is preshaped, and sits well on the distal femur. Several comments are helpful in establishing its correct placement: • As the lateral cortex slopes approximately 15% the insertion handle is usually raised approximately 10 to 15° to the horizontal plane of the floor. • The fixator is usually approximately 1 to 1.5 cm posterior to the most anterior aspect of the distal femoral condyle and approximately 1 to 1.5 cm cepha]ad to the distal femoral articular surface. Correct placement of tile fixator is often aided by "pushing" the fixator proximally, and then allowing the LISS fixator to "'settle" distally onto the normal flair of the femoral condyles. Counter pressure is placed on the medial aspect of the distal femoral condylar region, the hand guiding the insertion handle is raised approximately 10 to 15°, and the guide wire is then placed through drill sleeve "A." This guide wire should then be parallel to the joint surface of the distal articular surface, if 5 ° of distal femoral valgus is established. Small adjustments in this relationship can be made later m the sequence as noted below. Step 5: Check of Reduction: Rotation and Length: Placement of Proximal Guide Wire A check is made at this point via fluoroscopy in the AP plane to insure that the proper length has been reestablished in the injured extremity. At this point, the rotational profile of the limb is also assessed, utilizing the knowledge that the foot should be externally rotated 10 to 15 ~, assessment of the AP fluoroscopy, and evaluation of the skin lines in the distal femoral region. If in fact length and rotation are correct, then the proximal guide wire may be inserted after it is assured that the flxator is on the mid lateral aspect of the femur and in a proper rotationa! relationship. Assessment of the location of the proximal aspect of the fixator may be facilitated by making a larger incision (approximately 4 to 5 cm) over the proximal three screw holes (either 11, 12, and 13 for a 13-hole fixator; or holes 7, 8, and 9 for a 9-hole fixator), The incision is carried down in a longitudinal manner through the iliotibial band and vastus ]ateralis muscle so that direct palpation of the fixator and assessment of its relationship to the lateral cortex is possible, Additionally, lateral fluoroscopy can be utilized to assess placement of the flxator on the mid lateral aspect of the femur. Establishment of this is extremely important to insure proper proximal unicortical screw insertion. After proper length and rotation are assured, and appropriate positioning of the proximal aspect of the fixator on the mid lateral femur is established, the prox-
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Fig 5. (a, b) A 33 year old male sustained an A2 distal femur fracture. (c, d) Intraoperative views demonstrating a closed reduction of the fracture in both, the AP and lateral planes. (e) The LISS fixator is slid in a submuscular manner, and the guide wire is placed distally. The guide wire is parallel to the joint surface if appropriate alignment is achieved. (f) After appropriate length and rotation restoration, a guide wire is placed proximally.
Fig 5. (cont'd) (g) A "whirly bird" pulling device "fine-tunes" the reduction, and also ensures that the self-drilling, self-tapping screws do not push away the bone. (h,i) Immediate AP and lateral X-rays following LISS placement. Articular translation of 9 mm of the distal femoral block is seen. (j, k) Follow-up films at 5 months, The patient was full weight bearing at 10 weeks postoperative. imal guide wire may then be placed. At this point, corrections in sagittal plane alignment are possible, as noted below. Additionally, small corrections of adduction of the proximal fragment, or in varus/valgus alignment of the distal femoral condyle is possible. Step 6: Placement of Screws in the Distal Femoral Block At this point, a reassessment of the usual hyperextension and excess valgus deformities of the distal femoral condylar block is made. Hyperextension is corrected by repositioning of the supracondylar towel bumps, changing the direction of manual traction, and for manual pressure/"joystick" control of the distal femoral block. Correct varus/valgus alignment is then ensured. After the correct placement of the fixator on the distal femoral block is assured and after appropriate correction of any deformity is made, several screws may be placed distally. All screws are placed under saline cooling. SUBMUSCULAR PLATING OF THE DISTAL FEMUR
Step 7: Appropriate Reduction of the Proximal Femoral Shaft with Screw Fixation At this point, the fixator is in appropriate relationship of the distal femoral condyle and the length and rotation have been maintained--both by continued gentle manual traction and by the proximal guide wire. One has learned that perhaps manual pressure needs to be placed on the anterior distal aspect of the proximal fragment, or that one needs to correct an adduction deformity of the proximal fragment. Step 8: Additional Screw Placement Additional screws are subsequently placed both proximally and distally. In general, a total of 5 proximal and 5 distal screws are placed. In the setting of severe osteoporosis, 6 proximal and 6 distal screws may be utilized. 93
Step 9: Assessment of Fracture Reduction and Stability The knee is taken through a full gentle range of motion to ensure fracture fixation adequacy. Then, utilizing AP, lateral, and oblique radiographs, fracture reduction and fracture fixation is assessed. Specific questions to be answered in this assessment include: • How is the v a l g u s / v a r u s alignment? • Is there significant hyperextension of the distal femoral condyles? • Is there any sagittal plane deformity? • How is the placement of fixator or the mid lateral aspect of the femur? • Are all screws truly unicortical, or are some in the anterior or posterior cortex? • How is placement of the LISS fixator on the lateral aspect of the distal femoral condyle? • Are any distal screws either in the patellar groove or the intercondylar notch? (Although rare, this can occur with distal and either excessive anterior or posterior positioning of the fixator.) This can be assessed intraoperatively and via fluoroscopy utilizing the intercondylar notch view. Step 11: Closure
POSTOPERATIVE REHABILITATION Immediate mobilization of the patient and limb is begun postoperatively. A continuous passive motion machine is begun postoperatively. Full weight bearing is begun at 8 to 12 weeks or when significant callous formation in the supracondylar region is seen. No hinged knee braces are utilized.
SUMMARY As with any fracture, a preoperative understanding of the articular injury is vital in the treatment of supracondylar femur fractures. Submuscular fixation may add in minimizing surgical trauma to the metaphyseal/diaphyseal component of the fracture. Additionally, its use may allow optimal visualization of the articular surface if used in conjunction with the lateral peripatellar approach. As the metaphyseal fracture is not directly seen, increased attention to detail via fluoroscopic guidance is necessary for optimal reductions.
REFERENCES 1. Schatzker J, Home G, Waddell J: The Toronto experience with the supracondylar fracture of the femur, 1966-72. Injury 6:113-128, 1974 2. Schatzker J, Lambert DC: Supracondylar fractures of the femur. Clin Orthop 138:77-83, 1979 3. Siliski JM, Mahring M, Hofer HP: Supracondylar-intracondylarfractures of the femur. Treatment by internal fixation. J Bone Joint Surg Am 71:95-104, 1989 4. Wenzl H: [Results in 112 surgically treated distal femoral fractures]. Hefte Unfallheilkd 15-24, 1975 5. Olerud S: Supracondylar, intraarticular fracture of the femur. Results of operative reconstruction. Acta Orthop Scand 42:435-437, 1971 6. Olerud S: Operative treatment of supracondylar-condylar fractures of the femur. Technique and results in fifteen cases. J Bone Joint Surg Am 54:1015-1032, 1972 7. Ostrum RF, Geel C: Indirect reduction and internal fixation of supracondylar femur fractures without bone graft. J Orthop Trauma 9:278284, 1995
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8. Miclau T, Holmes W, Martin RE, et ah Plate osteosynthesis of the distal femur: Surgical techniques and results. J South Orthop Assoc 7:161-170, 1998 9. Bolhofner BR, Carmen B, Clifford P: The results of open reduction and Internal fixation of distal femur fractures using a biologic (indirect) reduction technique. J Orthop Trauma 10:372-377, 1996 10. Schatzker J: Fractures of the distal femur revisited. Clin Orthop 347:43-56, 1998 11. Henry SL, Trager S, Green Set al: Management of supracondylar fractures of the femur with the GSH intramedullarynail: Preliminary report. Contemp Orthop 22:631-640, 1991 12. Helfet DL, Lorich DG: Retrograde intramedullary nailing of supracondylar femoral fractures. Clin Orthop 350:80-84, 1998 13. Danziger MB, Caucci D, Zecher SB, et al: Treatment of intercondylar and supracondylar distal femur fractures using the GSH supracondylar nail. Am J Orthop 24:684-690, 1995 14. Johnson KD: Internal fixation of distal femoral fractures. Instr Course Lect 36:437-448, 1987 15. Johnson EE: Combined direct and indirect reduction of comminuted four-part intraarticular T-type fractures of the distal femur. Clin Orthop 231:154-162, 1988 16. Gerber C, Mast JW, Ganz R: Biological internal fixation of fractures. Arch Orthop Trauma Surg 109:295-303, 1990 17. Mast JW, Jakob R, Ganz R (eds): Planning and reduction technique in fracture surgery. New York, Springer-Verlag, 1989 18. Kinast C, Bolhofner BR, Mast JW, et al: Subtrochanteric fractures of the femur. Results of treatment with the 95 degrees condylar bladeplate. Clin Orthop 238:122-130, 1989 19. Rozbruch SR, Muller U, Gautier E, et al: The evolution of femoral shaft plating technique. Clin Orthop 195-208, 1998 20. Collinge C, Sanders R, DiPasquale T: Treatment of complex tibial periarticular fractures using percutaneous techniques. Clin Orthop 375:69-77, 2000 21. Blauth M, Bastian L, Krettek C, et al: Surgical options for the treatment of severe tibial pilon fractures: A study of three techniques. J Orthop Trauma 15:153-160,2001 22. Krettek C, Schandelmaier P, Miclau T, et al: Transarticular joint reconstruction and indirect plate osteosynthesis for complex distal supracondylar femoral fractures. Injury 28:31-41(Suppl 1), 1997 23. Krettek C, Schandelmaier P, Miclau T, et al: Minimally invasive percutaneous plate osteosynthesis (MIPPO) using the DCS in proximal and distal femoral fractures. Injury 28:20-30(Suppl 1), 1997 24. Krettek C, Schandelmaier P, Tscherne H: [Distal femoral fractures. Transarticular reconstruction, percutaneous plate osteosynthesis and retrograde nailing]. Unfallchirurg 99:2-10, 1996 25. Farouk O, Krettek C, Miclau T, et al: Minimally invasive plate osteosynthesis: Does percutaneous plating disrupt femoral blood supply less than the traditional technique? J Orthop Trauma 13:401-406, 1999 26. Zehntner MK, Marchesi DG, Burch H, et al: Alignment of supracondylar/intercondylar fractures of the femur after internal fixation by AO/ASIF technique. J Orthop Trauma 6:318-326, 1992 27. Sanders R, Swiontkowski M, Rosen H, et al: Double-plating of cornminuted, unstable fractures of the distal part of the femur. J Bone Joint Surg Am 73:341-346, 1991 28. Simonian PT, Thompson GJ, Emley W, et al: Angulated screw placement in the lateral condylar buttress plate for supracondylar femoral fractures. Injury 29:101-104, 1998 29. Frigg R, Appenzeller A, Christensen R, et al: The development of the distal femur Less Invasive Stabilization System (LISS). Injury 32:2431(Suppl 3), 2001 30. Perren SM: Evolution of the internal fixation of long bone fractures. The scientific basis of biological internal fixation: choosing a new balance between stability and biology. J Bone Joint Surg Br 84:10931110, 2002 31. Zlowodzki M, Williamson RS, Zardiackas LD et al: Biomechanical evaluation of the Less Invasive Stabilization System (LISS), angled blade plate and retrograde intramedullary nail for the fixation of distal femur fractures: An Osteoporotic Cadaveric Model. Orthopaedic Trauma Association 18th annual meeting 55:178-179, 2002 32. NoAuthors: Fracture and dislocation compendium. Orthopaedic Trauma Association Committee for Coding and Classification. J Orthop Trauma 10:1-154(Suppl 1), 1996 KREGOR ET AL
33. Sanders R, Regazzoni P, Ruedi TP: Treatment of supracondylarintracondylar fractures of the femur using the dynamic condylar screw. J Orthop Trauma 3:214-222, 1989 34. Behrens F, Brueckmann FR, Helfet DL: Management of distal femoral frac~res. Contemp Orthop 22:193-222, 1991 35. Henry SL: Supracondylar femur fractures treated percutaneously. Clin Orthop 375:51--59,2000 36. Iannacone WM, Bellnett FS, DeLong WG, Jr, et al: Initial experience with the treatment of supracondylar femoral fractures using the supracondylar intramedullary nail: A preliminary report. J Orthop Trauma 8:322-327, ].994 37. Seligson D: Treatment of supracondylar fractures of the femur. J Trauma 49:360, 2000 38. Leung KS, Shen WY, So WS, et al: Interlockingintramedullarynailing for supracondylar m~d intercondytar fractures of the distal part of the femur. J Bone ~oint Surg Am 73:332~340, 1991 39. Kregor PJ: Distal femur fractures with complex articular involvemen~: Management by articular exposure and submuscular fixation. Orth0p Clin North Am 33:153-175, 2002 40. ~ettek C, Schandelmaier P, Richter M, et al: [Distal femoral fractures]. Swiss Surg 263-278, 1998
SUBMUSCULAR PLATING OF THE DISTAL FEMUR
41. Merchan EC, Maestu PR, Blanco RP: Blade-plating of closed displaced supracondylar fractures of the distal femur with the AO system. J Trauma 32:174-178. 1992 42. Shewring DJ, Meggitt BF: Fractures of the distal femur treated with the AO dynamic condylar screw. J Bone Joint Surg Br 74:122-125,1992 43. Lucas SE. Seligson D, Henry SL: Intramedullary supracondylar nailing of femoral fractures. A preliminary report of the GSH supracondylar nail. Clin Orthop 296:200-206, 1993 44. Marsh JL, Jansen H, Yoong HK, et al: Supracondylar fractures of the femur treated by external fixation. J Orthop Trauma 11:405-410,1997 45. Hutson JJ, Jr., Zych GA: Treatment of comminuted intraarticular distal femur fractures with limited internal and external tensioned wire fixation. J Orthop Trauma 14:405-413, 2000 46. Kregor PJ, Stannard J, Zlowodzki IV[, et al: Distal femoral fracture fixation utilizing the Less Invasive Stabilization System (L.LS.S3: the technique and early results. Injury. 32:32-47(Suppl 3), 2001 47. Schutz M, Muller M, Krettek C, et al: Minimally invaslve fracture stabilization of distal femoral fractures with the LISS: A prospective multicenter study. Results of a clinical study with special emphasis on difficult cases. Injury 32:48-54(Suppl 3), 2001
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A va:¢iety of implants are available for the treatment of distal femur fractures. However, continued problems include infecl~on, nonunion, need for bone grafting, malunions, joint stiffness, and loss of fixation. "Biological plating" emphasizes maintenance of the soft tissue environment around the fracture. The concept of "biological plating" in supracondylar femur fractures has been very advantageous. The Less Invasive Stabilization System (LISS) for fractures of the distal femur combines these biological advantages of submuscular fixation with the biomechanical advantage of fixed angled, locked screws for fixation of the distal femoral block. The LISS may be particular helpful in the setting of complex articular pathology, a short distal segment, and osteoporotic bone. LISS methodology relies on traditional internal fixation of the articular surface, closed reduction of metaphyseal/diaphyseal component of the fracture, and placement of a submuscular LISS fixator. Percutaneous locking screws are then placed for proximal fixation. In this review, the evolution of submuscular fixation of supracondylar femur fractures and the technique are described. KEY WORDS: aupracendylar, femur, submuscular, plate, fixation © 2003 Elsevier Inc. All rights reserved.
Distal femur fractures continue to be problematic for the clinician. Emphasis on internal fixation for supracondylarintercondylar femur fractures over the past three decades has improved the outcome from these injuries. 1-9 However, continued problems include infection, nonunion, need for bone graft'mg, malunions, joint stiffness, and loss of fixation. 1-6,845 "Biological plating," as popularized b y Mast, Jakob, and Ganz, emphasizes maintenance of the soft tissue environment around the fracture. ~6,17Its tenets include restoration of length, rotation, and alignment-without the need for precise anatomic restoration of every cortical fragment. "Leaving the fragments alone" results in a more predictable ,and more expedient fracture consolidation in these areas. Its advantages have been seen in subtrochanteric femur fractures, ~8 femoral shaft fractures, 19 tibial shaft fractures 2°, and pilon fractures. 21 The concept of "biological plating" in supracondylar femur fractures has also been very advantageous. Bolhofner and co-workers reported on 57 cases of supracondylar femur fractures treated with biological plating techniques utilizing the condylar blade plate or condylar buttress plate. 9 In this series, emphasis was placed on allowing the implant, after being connecte:d to the distal femoral block, to aid in reduction of the fracture. In a series in which no bone grafting was utilized, time to radiographic union and full From the Division of Orthopedic Trauma, Vanderbilt University Medical Center, Nashville, TN, USA; Division of Orthopedic Surgery, University of Alabama Medical Center, Birmingham, AL, USA; Regions Hospital, University of Minnesota, St. Paul, MN, USA. Address reprint requests to Philip James Kregor, MD, 2100 Pierce Avenue, 131 Medical Center South, Nashville, TN, 37232. E-mail: philip.kregor @vanderbilt.edu. © 2003 Elsevier Inc. All rights reserved, 1048-6666/03/1302-0000530.00/0 doi:l 0.1053/otor.2003.0168
Operative Techniques in Orthopaedics, Vol 13, No 2 (April), 2003: pp 85-95
weight bearing was 10.7 weeks. There were 2 delayed unions, but no persistent nonunions. This is in sharp contrast to series involving traditional open reduction/internal fixation. 1-4,1° Miclau and co-workers noted bone grafting rates ranging between 0 to 87% with traditional internal fixation. 8 "Biological plating" for supracondylar femur fractures gradually evolved into submuscular plating. Krettek and co-workers described the use of a dynamic condylar screw placed in a submuscular martrter. 22-24 In this method, the articular surface is reduced after appropriate visualization, and internal fixation of the articular surface is then performed. It should be emphasized that nothing is "new" with regards to reduction and fixation of the articular surface. The articular injury must have an appropriate preoperative assessment, adequate surgical exposure, exact repositioning/reduction, and stable fixation. It is only after the articular reduction is accomplished that the submuscular method may be utilized to address the metaphyseal/diaphyseal component of the fracture. Thus, the surgeon should not compromise the articular surface exposure or reduction because submuscular methods are utilized. The premise of submuscular sliding of a plate along the femoral shaft is based on the naturally existing potential space between the undersurface of the vastus lateralis and the periosteum of the femoral shaft. The surgeon can exploit this space by passing the plate along the femoral shaft. A natural concern would potentially be increased vascular damage to the femoral shaft by injuring perforating vessels. This has not been the case, as demonstrated experimentally. Vascular injection dye studies have demonstrated that submuscular plate application disrupts the femoral blood supply less in 70% of specimens when 85
comparing it to the contralateral side with traditional plate osteosynthesis. 25 Although submuscular plating preserves the vascularity around the fracture, reduction difficulties remain, or are even greater. Malreductions of the distal femur are probably under-recognized. Zehntner and co-workers reported on an intermediate follow-up (5 years 7 months average) of 57 supracondylar femur fractures treated with traditional plating techniques by experienced surgeons and found varus/valgus malreductions greater than 5 ° in 26% of cases. 26 In addition, sagittal plane deformities (apex anterior or posterior) were seen in 22%, and rotational deformities in 17%. With indirect, submuscular plating techniques, malalignment can be even more problematic. Krettek and co-workers reported on 8 supracondylar-intracondylar femur fractures (AO/OTA classification C2C3) treated with submuscular plate fixation and noted 2 varus/valgus deformities greater than 5 °, 2 leg length discrepancies greater than 10 mm, and two rotational deformities of 15°. 22 Thus, if the surgeon wishes to gain the advantages of submuscular fixation, surgical strategies must be developed to minimize malalignment problems. In addition to reduction difficulties, varus collapse of the distal femoral block continues to be problematic. Distal fixation is critical especially in osteoporotic bone. In the past decade, this problem has been addressed via double plating of the distal f e m u r , 27 medial external fixator placement, and placement of a diagonal distal femoral screw. 28 Recently, "locked" plating has become available. 29,3° In locked plates, screws have a threaded screw head which then threads into a recipient threaded screw hole in the plate. A locked plate can best be thought of as an "internal fixator." As with an external fixator, principles include: 1. Classic articular reduction and fixation, 2. "Spanning" the zone of comminution in the diaphyseal/metaphyseal area of the fracture, and 3. Utilization of a longer "construct" than with normal plating. In an effort to combine the biological advantages of submuscular plating and the biomechanical advantages of fixed-angled or "locked" plating, the Less Invasive Stabilization System (LISS) was developed (Fig 1). Its characteristics include: 1. Multiple, fixed angled screws which lock into the distal end of the fixator, and 2. An insertion handle that allows for submuscular sliding of the fixator and for placement of percutaneous, self-drilling, unicortical screws for fixation of the diaphyseal component of the fractures. Biomechanical testing has shown that a blade plate/femur construct and a retrograde I M N / f e m u r construct often results in loss of distal fixation, while a LISS/femur construct maintains fixation of the implant at higher loads. 31 The load to failure in one-time axial loading is significantly higher when using a LISS in comparison to a blade plate. It is the purpose of this paper to outline the surgical indications, surgical technique, and complications associated with its use. Case examples will be used to illustrate its use. Secondary surgical procedure rates after primary
86
fixation with commonly used devices such as a blade plate, retrograde nail, dynamic condylar screw, or external fixation are reported between 0% and 25.7% (Table 1). It should be understood that while the LISS is a specific device, the two basic features of allowing submuscular fixation and fixed angled screw fixation are its key characteristics. As with all fracture surgery, it is the surgical technique that is more important than the actual implant. Submuscular fixation can also be performed with standard dynamic condylar screw plates, and newer locking condylar buttress plates.
SURGICAL INDICATIONS Supracondylar femur fractures are best classified via the A O / O T A Classification (Fig 2). 32 For A-type (nonarticular supracondylar femur fractures) and C1/C2 (supracondylar femur fractures with simple articular splits), a variety of implants have proved efficacy: 95 ° Dynamic Condylar Screw, 33 95 ° Condylar Blade Plate, 1-3,7,9A°,34Retrograde Supracondylar Nail, 11-13,35-37 and Antegrade Intramedullary Nailing. 38 Thus, the LISS may not add a distinct advantage in all cases. There are situations, however, where the LISS may offer particular benefit: 1. Treatment of a supracondylar femur fracture with a very short distal segment, especially in the setting of osteoporosis. In such a situation, fixation of the distal femoral block with an intramedullary nail may be difficult and problematic (Fig 3). 2. Treatment of supracondylar femur fractures above total knee arthroplasty, especially when the distal femoral block is short a n d / o r osteoporotic. 3. Treatment of the high-energy C3 distal femur fracture. 39 The C3 distal femur frac~re remains a difficult surgical challenge because of several factors: 1. Adequate exposure of articular surface, especially of the medial femoral condyle, is challenging without large surgical exposure a n d / o r tibial tubercle osteotomy,
2. Standard implants utilized for other supracondylar femur fractures (eg, condylar blade plate and retrograde nails) may jeopardize the articular surface reduction and fixation, 3. Especially in the setting of a short distal segment, varus collapse, a n d / o r loss of fixation of the distal femoral block can occur.
INITIAL S T A B I L I Z A T I O N A N D P A T I E N T ASSESSMENT After appropriate history and physical examination, provisional stabilization of the femur fracture may be addressed by utilizing a long-leg splint placed while the leg is held in manual distal traction. As with most closed reduction of fractures, an emphasis is placed on early intervention. After stabilization of life-threatening injuries, the supracondylar femur fracture may be addressed. Surgical stabilization should proceed with an adequate understanding of the fracture, an appropriate surgical team,
KREGORET AL
D
;i
Fig 1. (a) The LISS consists of an anatomically shaped, precontoured fixator with an accompanying outrigger device which allows for submuscuiar fixator application. (b,c) The screws placed through drill sleeves are self-drilling and self-tapping. They can be placed percutaneously, and are locked into the fixator, thus acting as "mini-blade plates" in the distal femoral block. (c) After traditional internal fixation of the articular surface, the mataphyseal/diaphyseal component of the fracture is "spanned" with the LIISS internal fixator. SUBMUSCULAR PLATING OF THE DISTAL FEMUR
87
T A B L E 1. Nonunion and Infection Rates in Treatment of Supracondylar Femur Fractures in the Literature n
Year
Implant/Technique
Nonunion Rate*
Infection Rate
Schatzker et al (2) Sanders et al (27) Merchan et al (41) Shewring et al (42) Lucas et al (43) lannacone et al (36) Bolhofner et al (9) Marsh et al (44)
35 9 42 21 25 41 57 13
1979 1991 1992 1992 1993 1994 1996 1997
Mostly blade plate Double Plating Blade Plate DCS Retrograde IMN Retrograde IMN Blade Plate or CBP/Indirect Reduction External Fixation
25.7% 0% 7.1% 9.5% 16% 19.5% 0% 0%
Hutson et al (45) Kregor et al (46) Schuetz et al (47)
16 66 99
2000 2001 2001
Limited Internal Fixation + ExFix LISS LISS
12.5% 5% 9%
0% 0% 7.1% 0% 4% 0% 1.8% 7.7% 18.8% (1/3 Pin) 3% 7%
*Includes secondary surgical procedures for delayed unions.
and a stabilized patient. If these conditions are not met, especially in the setting of high-energy, highly displaced fractures, a spanning external fixator is an excellent temporary device which stabilizes the limb, maintains length of the extremity, and minimizes fracture motion contributing to further soft tissue swelling. Pins of the external fixator placed at a significant distance from the knee joint (eg, proximal femur and distal tibial) will not contaminate the future operative site for the supracondylar femur fracture. Excellent quality AP, lateral and oblique radiographs are mandatory before preoperative planning for stabilization of the fracture. Poor quality anterior-posterior (AP) and lateral radiographs, especially in the shortened leg, often do not delineate significant articular pathology. Oblique radiographs are necessary to better delineate the intercondylar pathology because the patella often obscures the intercondylar fracture. In cases of complex multiplane fractures, axial computerized tomography (CT), with frontal and sagittal plane reconstructions may be helpful in planning the surgical stabilization.
SURGICAL TECHNIQUE Patient Positioning
The leg length and rotational profile of the contralateral extremity, if possible, is examined preoperatively to ascertain the correct length and rotational profile of the distal femur. A towel bump is then placed under the ipsilateral buttock to counteract the normal external rotation of the lower extremity. If the pelvis is tilted up approximately 15° on the involved side, and the rotational profile of the injured femur is correctly reestablished, the foot will be 5 to 10° externally rotated in most cases at the end of the case. This is a helpful check to avoid serious rotational mismatches. Operative intervention is best performed on a completely radiolucent table, which allows complete imaging of the lower leg. Appropriate padding under the uninvolved extremity is placed, and the uninvolved extremity is secured in place. Prep and drape should allow for complete exposure of the proximal femur and hip region, especially if a longer fixator is to be utilized. 88
Fig 2. The AO/OTA classification for supracondylar/intercondylar femur fractures is helpful to delineate surgical approach and implant choice. "A" fractures are extra-articular, "B" fractures are isolated condylar fractures, and "C" fractures are intraarticular. A "C3" fracture is differentiated from "C1/C2" fractures by its complex articular pathology. (From Hansen ST, Swiontkowski MF (eds): Orthopaedic Trauma Protocols. Raven Press, New York, 1993, p296; with permission.) KREGOR ET AL
Fig 3. (a) A 63 year old female sustained a C2 distal femur fracture, (b) immediate postoperative films. (c) Varus collapse of the distal femoral block resulting in destruction of the lateral femoral condyle, (d) Femoral condyles with articular surface destruction (arrow) of lateral femoral condyle (LFC) seen at time of revision surgery, SUBMUSCULAR PLATING OF THE DISTAL FEMUR 89
Surgical Approach Through a careful examination of the injury radiographs, the following questions should be answered: 1. Is there involvement of the articular surface? 2. If so, is the involvement simple or complex? Is the intercondylar fracture central in the patellar groove, or is it more medial? 3. Are there frontal plane ("Hoffa') fractures in either the medial or lateral femoral condyle? 4. Are there separate intercondylar notch osteochondral fragments? For nonarticular fractures (AO/OTA Classification A1A3) and fractures with simple articular involvement (AO/ OTA Classification C1 and C2), a standard anterolateral approach to the femur is performed, as described below. For multiplane articular involvement, medial-based intercondylar splits, "Hoffa" fractures, and separate intercondylar notch fragments, a lateral peripatellar approach is utilized. 4° A standard anterolateral approach to the distal femur is performed with the patient in the supine position. A curvilinear incision is utilized which begins approximately 3 to 6 cm proximal to the tibial tubercle and curves slightly anterior to the mid lateral aspect of the distal femur. For a nonarticular fracture, the incision utilized is approximately 6 cm, while for articular fractures, the incision is 8 to 10 cm. If articular visualization is necessary, the joint capsule may be divided in line with the split in the iliotibial band distal to the level of the lateral meniscus. A carefully placed Hohmann retractor on the medial aspect of the medial femoral condyle allows for visualization of the distal articular surface. The lateral peripatellar approach22, 24 allows excellent visualization of the entire articular surface, and it is particularly helpful in cases of multiplane articular involvement. The extensor retinaculum and mechanism is longitudinally divided in a curvilinear manner, leaving a cuff of tissue to the lateral aspect of the patella for later repair. The patella may be everted, affording visualization, reduction, and fixation of the articular surface. The LISS (or a submuscular plate) may then be inserted through the lateral peripatellar wound. Articular Fracture Reduction and Fixation
Reduction aids for the articular surface that may be helpful include: • Schantz pins utilized as joysticks in the medial and lateral femoral condyle which aid in reduction of the intercondylar fracture, • Large pointed reduction "Weber" clamps, or large pelvic reduction clamps, which compress the lateral and medial femoral condyle blocks together, • Provisional K-wires, which can hold reduction of articular blocks until definitive lag screw fixation is achieved, and • Dental picks, which are helpful in fine manipulation of articular segments. After reduction is achieved, multiple 3.5 mm cortical lag screws are utilized in a lateral to medial direction for fixation of intercondylar fractures, or in an anterior to 90
Fig 4. Intraoperative photo of supracondylar towel bump in position posterior to the supracondylar region, The LISS fixator has been slid in a submuscular manner and proximal percutaneous screws are being placed.
posterior direction for fixation of "Hoffa" fractures. Minifragment 2.7-ram lag screws are also utilized, especially for fixation of small osteochondral fragments in the intercondylar notch. After reduction and fixation of the articular surface is achieved, attention is then turned to reduction and fixation of the metaphyseal/diaphyseal component of the fractures.
Reduction aids for LISS Fixation of Distal Femoral Fractures The goal of LISS fixation is to maintain the soft tissue environment around the metaphyseal/diaphyseal component of the fracture. This is performed utilizing closed reduction techniques. A variety of "aids" are utilized which facilitate the closed reduction techniques. These include: 1. Early Intervention: As mentioned above, fractures are addressed as soon as possible. If high-energy, shattered fractures are not stabilized in the first 24 hours, a spanning external fixator is placed to maintain the length of the fractured extremity. 2. Chemical Paralysis: Complete clinical paralysis of the patient is necessary. 3. Supracondylar Towel Bumps: Supracondylar towel bumps of 10, 12, and 15 rolled surgical towels wrapped with an elastic bandage are utilized to be placed in the area posterior to the supracondylar region. The towel bumps aid in reduction of the common hyperextension of the distal femoral fragment (Fig 4). In addition, the bump acts as a fulcrum for the vector force of the manual traction pull. Relatively small adjustments in the size a n d / o r location of the towel bumps cam make large differences in sag!ttal plane correction of the fracture. 4. Manual Traction: Hard manual traction is helpful to establish length and rotation, and may facilitate varus/valgus correction. Manual traction is applied to the ankle region, and with a force vector that is directed posteriorly. Utilizing the towel bumps as afulcrum, the manual traction facilitates reduction of the hyperextension deformity of the distal femoral condyle. KREGOR ET AL
5. Distal F e m o r a l C o n d y l e Schantz Pin: Especially in cases of a v e r y short distal f e m o r a l segment, correction of the h y p e r e x t e n s i o n d e f o r m i t y m a y be difficult. This m a y be a i d e d b y an anterior to posterior Schantz pin, w h i c h m a y act as a "joystick" to derotate the distal f r a g m e n t into a p p r o p r i a t e reduction. 6. " W h i r l y b i r d " A p p r o x i m a t i n g Device: The "Whirlyb i r d " device is a self-drilling, self-tapping p i n that can be drilled into the f e m o r a l cortex, either in the distal or p r o x i m a l regions. A t u r n i n g n u t against the outrigger LISS insertion device will actually a p p r o x i m a t e the f e m o r a l cortex to the LISS fixator. The device m a y be, therefore, utilized to afford small corrections in v a r u s / valgus deformities. M o r e t h a n one " W h i r l y b i r d " device m a y be u s e d together to afford small translation corrections of the p r o x i m a l segment. P l a c e m e n t of the " W h i r l y b i r d " device can be likened to a c l a m p placer m e n t , as it will stabilize the reduction as the selfdrilling screws are inserted. 7. F e m o r a l Distractor or External Fixation: The f e m o r a l distractor or external fixator m a y be utilized to obtain a n d m a i n t a i n the m e t a p h y s e a l / d i a p h y s e a l reduction. H o w e v e r , its use m a y m a k e fine a d j u s t m e n t s in fracture r e d u c t i o n difficult. 8. M a n u a l P r e s s u r e : M a n u a l p r e s s u r e utilizing a large mallet is occasionally n e c e s s a r y to p u s h m e d i a l l y on an a d d u c t e d a n d / o r flexed p r o x i m a l f r a g m e n L In addition, it m a y be utilized on the distal f r a g m e n t to correct excess valgus.
SURGICAL SEQUENCE OF LISS FIXATION (FIG 5) Just a s w i t h p l a c e m e n t of a n y fixation device for distal f e m o r a l fractures, there is a well defined, stepwise process for LISS fixation of distal f e m o r a l fractures. A l t h o u g h there m a y b e variations on this sequence, it i s helpful t o a d d r e s s each step in the surgical sequence. The LISS fixation sequence begins after articular fracture r e d u c t i o n a n d fixation. Step 1: Provisional Fracture Reduction ("Learning the Fracture") Before the LISS fixator is inserted, manual traction is applied, the supracondylar bumps are placed, and the fracture reduction is visualized on both AP and lateral fluoroscopy. The surgeon can then note facts such as hyperextension of the distal femoral condyle, flexion and/or adducti0n of the proximal femoral shaft, and/or valgus of the distal femoral condyles. Adjustments in position and/or size of the supracondylar bumps,, vector force direction of m~nua! traction, and correction of deformities utilizing the large mallet can then be made. Although the insertion handle for the LISS is radiolucent, improved visualization of the fracture reduction is seen before LISS insertion. Step 2: LISS Insertion The LISS fixator is inserted through either the anterolateral incision or lateral peripatellar approach. The fixator is preshaped to account for the anterior bow of the femur. This step can be done under brief line fluoroscopy and is aided by: • The tactile sensation of the proximal tip of the fixator or the lateral cortex, and
SUBMUSCULARPLATINGOF THE DISTAL FEMUR
. Assessing the relationship of the insertion handle (ie, "outrigger device") with regards to the lateral aspect of the thigh. A common tendency is to direct the fixator posteriorly; this can be avoided by careful attention to the last step. Step 3: Connection of the Proximal Locking Sleeve Connecting Bolt Through an incision over either the # 9-hole or the # 13-hole, a proximal connecting bolt is screwed into the proximal end of the flxator. This creates a fixed parallelogram that facilitates further manipulation of the fixator on the mid lateral aspect of the femur. Step 4: Establishment of Appropriate Placement of LISS Fixator on Distal Femoral Condyle The LISS fixator is preshaped, and sits well on the distal femur. Several comments are helpful in establishing its correct placement: • As the lateral cortex slopes approximately 15% the insertion handle is usually raised approximately 10 to 15° to the horizontal plane of the floor. • The fixator is usually approximately 1 to 1.5 cm posterior to the most anterior aspect of the distal femoral condyle and approximately 1 to 1.5 cm cepha]ad to the distal femoral articular surface. Correct placement of tile fixator is often aided by "pushing" the fixator proximally, and then allowing the LISS fixator to "'settle" distally onto the normal flair of the femoral condyles. Counter pressure is placed on the medial aspect of the distal femoral condylar region, the hand guiding the insertion handle is raised approximately 10 to 15°, and the guide wire is then placed through drill sleeve "A." This guide wire should then be parallel to the joint surface of the distal articular surface, if 5 ° of distal femoral valgus is established. Small adjustments in this relationship can be made later m the sequence as noted below. Step 5: Check of Reduction: Rotation and Length: Placement of Proximal Guide Wire A check is made at this point via fluoroscopy in the AP plane to insure that the proper length has been reestablished in the injured extremity. At this point, the rotational profile of the limb is also assessed, utilizing the knowledge that the foot should be externally rotated 10 to 15 ~, assessment of the AP fluoroscopy, and evaluation of the skin lines in the distal femoral region. If in fact length and rotation are correct, then the proximal guide wire may be inserted after it is assured that the flxator is on the mid lateral aspect of the femur and in a proper rotationa! relationship. Assessment of the location of the proximal aspect of the fixator may be facilitated by making a larger incision (approximately 4 to 5 cm) over the proximal three screw holes (either 11, 12, and 13 for a 13-hole fixator; or holes 7, 8, and 9 for a 9-hole fixator), The incision is carried down in a longitudinal manner through the iliotibial band and vastus ]ateralis muscle so that direct palpation of the fixator and assessment of its relationship to the lateral cortex is possible, Additionally, lateral fluoroscopy can be utilized to assess placement of the flxator on the mid lateral aspect of the femur. Establishment of this is extremely important to insure proper proximal unicortical screw insertion. After proper length and rotation are assured, and appropriate positioning of the proximal aspect of the fixator on the mid lateral femur is established, the prox-
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Fig 5. (a, b) A 33 year old male sustained an A2 distal femur fracture. (c, d) Intraoperative views demonstrating a closed reduction of the fracture in both, the AP and lateral planes. (e) The LISS fixator is slid in a submuscular manner, and the guide wire is placed distally. The guide wire is parallel to the joint surface if appropriate alignment is achieved. (f) After appropriate length and rotation restoration, a guide wire is placed proximally.
Fig 5. (cont'd) (g) A "whirly bird" pulling device "fine-tunes" the reduction, and also ensures that the self-drilling, self-tapping screws do not push away the bone. (h,i) Immediate AP and lateral X-rays following LISS placement. Articular translation of 9 mm of the distal femoral block is seen. (j, k) Follow-up films at 5 months, The patient was full weight bearing at 10 weeks postoperative. imal guide wire may then be placed. At this point, corrections in sagittal plane alignment are possible, as noted below. Additionally, small corrections of adduction of the proximal fragment, or in varus/valgus alignment of the distal femoral condyle is possible. Step 6: Placement of Screws in the Distal Femoral Block At this point, a reassessment of the usual hyperextension and excess valgus deformities of the distal femoral condylar block is made. Hyperextension is corrected by repositioning of the supracondylar towel bumps, changing the direction of manual traction, and for manual pressure/"joystick" control of the distal femoral block. Correct varus/valgus alignment is then ensured. After the correct placement of the fixator on the distal femoral block is assured and after appropriate correction of any deformity is made, several screws may be placed distally. All screws are placed under saline cooling. SUBMUSCULAR PLATING OF THE DISTAL FEMUR
Step 7: Appropriate Reduction of the Proximal Femoral Shaft with Screw Fixation At this point, the fixator is in appropriate relationship of the distal femoral condyle and the length and rotation have been maintained--both by continued gentle manual traction and by the proximal guide wire. One has learned that perhaps manual pressure needs to be placed on the anterior distal aspect of the proximal fragment, or that one needs to correct an adduction deformity of the proximal fragment. Step 8: Additional Screw Placement Additional screws are subsequently placed both proximally and distally. In general, a total of 5 proximal and 5 distal screws are placed. In the setting of severe osteoporosis, 6 proximal and 6 distal screws may be utilized. 93
Step 9: Assessment of Fracture Reduction and Stability The knee is taken through a full gentle range of motion to ensure fracture fixation adequacy. Then, utilizing AP, lateral, and oblique radiographs, fracture reduction and fracture fixation is assessed. Specific questions to be answered in this assessment include: • How is the v a l g u s / v a r u s alignment? • Is there significant hyperextension of the distal femoral condyles? • Is there any sagittal plane deformity? • How is the placement of fixator or the mid lateral aspect of the femur? • Are all screws truly unicortical, or are some in the anterior or posterior cortex? • How is placement of the LISS fixator on the lateral aspect of the distal femoral condyle? • Are any distal screws either in the patellar groove or the intercondylar notch? (Although rare, this can occur with distal and either excessive anterior or posterior positioning of the fixator.) This can be assessed intraoperatively and via fluoroscopy utilizing the intercondylar notch view. Step 11: Closure
POSTOPERATIVE REHABILITATION Immediate mobilization of the patient and limb is begun postoperatively. A continuous passive motion machine is begun postoperatively. Full weight bearing is begun at 8 to 12 weeks or when significant callous formation in the supracondylar region is seen. No hinged knee braces are utilized.
SUMMARY As with any fracture, a preoperative understanding of the articular injury is vital in the treatment of supracondylar femur fractures. Submuscular fixation may add in minimizing surgical trauma to the metaphyseal/diaphyseal component of the fracture. Additionally, its use may allow optimal visualization of the articular surface if used in conjunction with the lateral peripatellar approach. As the metaphyseal fracture is not directly seen, increased attention to detail via fluoroscopic guidance is necessary for optimal reductions.
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