Treatment of Proximal Tibia Fractures Using the Less Invasive Stabilization System
Surgical Experience and Early Clinical Results in 77 Fractures
Peter A. Cole, MD,* Michael Zlowodzki, MD,† and Philip J. Kregor, MD†
Objective:To summarize the surgical experience and clinical re- sults of the first 89 fractures of the proximal tibia treated with the Less Invasive Stabilization System (LISS; Synthes, Paoli, PA).
Design: Retrospective analysis of prospectively enrolled patients into a database.
Setting:Academic level I trauma center.
Subjects/Participants:Eighty-seven consecutive patients with 89 proximal tibia fractures (AO/OTA type 41 and proximal type 42 frac- tures) treated by 2 surgeons. Seventy-five patients with 77 fractures were followed until union. The mean follow-up was 14 months (range: 3–35 months). There were 55 closed fractures and 22 open fractures.
Intervention:Surgical reduction and fixation of fractures, followed by rehabilitation.
Main Outcome Measurements:Perioperative and postoperative complications, postoperative alignment, loss of fixation, time to full weight bearing, radiographic union, and range of motion.
Results:Seventy of 77 fractures healed without major complications (91%). There were 2 early losses of proximal fixation, 2 nonunions, 2 deep delayed infections, and 1 deep peroneal nerve palsy. Other com- plications included a superficial wound infection and 3 seromas. Post- operative malalignment occurred in 7 patients with 6° to 10° of angu- lar deformity (6 flexion/extension and 1 varus/valgus malalign- ments), and an eighth patient had a 15° flexion deformity. In 4 patients, the hardware was removed at an average of 13 months be- cause of irritation (5%). The mean time for allowance of full weight bearing was 12.6 weeks (range: 6–21 weeks), and the mean range of final knee motion was 1° to 122°.
Conclusions:The LISS provides stable fixation (97%), a high rate of union (97%), and a low (4%) rate of infection for proximal tibial fractures. The technique requires the successful use of new and unfa- miliar surgical principles to effect an accurate reduction and accept- able rate of malalignment.
Key Words:tibia fracture, Less Invasive Stabilization System, less invasive, minimally invasive, locked plate, submuscular plating (J Orthop Trauma2004;18:528–535)
S
urgical treatment of high-energy, bicondylar, tibial plateau fractures and proximal tibial shaft fractures remains prob- lematic. Problems common with the bicondylar tibial plateau fractures include wound complications, infection, varus col- lapse, knee stiffness, and articular malreductions.1Intramed- ullary (IM) nailing of proximal tibial shaft fractures is com- monly associated with malalignment of the proximal segment, most commonly seen as flexion and valgus at the fracture site.2,3The use of locked internal fixators placed in a submus- cular manner may provide some advantages in the treatment of both types of fractures. The Less Invasive Stabilization System (LISS; Synthes, Paoli, PA) for proximal tibia fractures is a pre- contoured lateral implant accompanied by locking screws proximal and distal to the fracture. The locking nature of the proximal screws may allow for omission of direct medial col- umn fixation. An insertion guide for the implant allows for the placement of the locking screws percutaneously, thus facilitat- ing closed reduction and internal fixation using indirect reduc- tion of the metaphyseal–diaphyseal component of the fracture.
The LISS technique and technology used for proximal tibia fracture surgery have been previously described in detail and duplicate the surgical methods used in the current study.4
In the case of high-energy, bicondylar, tibial plateau fractures, the tibial LISS may be helpful in avoiding wound complications, infection, and varus collapse. The submuscular passage of the fixator facilitates smaller incisions in the proxi- mal tibial region, although it still mandates traditional articular reduction. Its biomechanical characteristics should aid in pre- venting varus collapse. In the case of proximal tibial shaft frac-
Accepted for publication July 6, 2004.
From the *Department of Orthopedic Surgery, University of Minnesota, Re- gions Hospital, St. Paul, MN, and †Division of Orthopedic Trauma, De- partment of Orthopedic Surgery, Vanderbilt University Medical Center, Nashville, TN.
Reprints: Peter A. Cole, MD, Department of Orthopedic Surgery, University of Minnesota, Regions Hospital, 640 Jackson Street, St. Paul, MN (e-mail:
peter.a.cole@healthpartners.com).
Copyright © 2004 by Lippincott Williams & Wilkins
tures, the possible advantages for its use are optimal fixation of the proximal segment, the ability to perform fixation with the knee completely extended, and the lack of deforming forces on the fracture during implant insertion.
The purpose of this article is to present the surgical ex- perience of 2 surgeons and the early clinical results of 89 con- secutively treated tibial fractures using the tibia LISS. Our hy- pothesis was that its use in bicondylar tibial plateau fractures and proximal tibial fractures would lessen the commonly seen complications noted previously.
MATERIALS AND METHODS
Between November 1998 and December 2002, 2 sur- geons at 4 institutions prospectively enrolled into a database 87 consecutive patients who sustained a proximal tibia fracture with diaphyseal–metaphyseal dissociation with or without ar- ticular involvement (89 fractures). Types of fractures included proximal tibia (AO/OTA type 41-A2, -A3, -C1, -C2, and -C3) and/or proximal tibia shaft (proximal AO/OTA type 42) frac- tures. All these patients were treated with the tibia LISS. The preliminary experience of the first 54 patients in this series was previously reported.4
Three patients in this series died within the first week after the injury, and 1 patient died 2 months after the injury, with all deaths related to causes unrelated to the tibial fracture.
Eight patients were lost to follow-up. We thus did not have follow-up information on 12 patients with 12 fractures. This left 75 patients with 77 fractures, who made up the study group. Radiographic healing was defined as bridging of 3 of 4 cortices on anterior-posterior and lateral radiographs. Clinical healing was defined as the ability to bear full weight and lack of pain with a varus and valgus stress to the injured tibia. Each of these patients was followed until clinical and radiographic healing had occurred, thus yielding a follow-up rate of 87% at a mean of 14 months (range: 3–35 months) after surgery. The attending surgeon was responsible for follow-up in all cases.
The mean age of the patients was 45 years (range: 16–82 years). There were 22 female patients and 53 male patients.
The mechanism of injury was a motor vehicle collision in 40 patients, pedestrian versus motor vehicle collision in 8 pa- tients, a fall or twisting injury in 16 patients, a gunshot injury in 6 patients, and other high-energy mechanisms in 5 patients.
Eleven patients in the study group sustained multisystem trauma (Injury Severity Score >25).
The 77 fractures comprised 42 fractures involving the proximal tibia only (AO/OTA type 41), 16 fractures involving the proximal third of the shaft only (AO/OTA type 42), and 19 proximal tibia fractures (AO/OTA type 41) that were also as- sociated with an ipsilateral tibial shaft fracture (OTA type 42) (Fig. 1).
The 42 isolated proximal fractures (OTA type 41) were classified as follows: 3 A2, 3 A3, 11 C1, 4 C2, and 21 C3 fractures. The 16 isolated shaft fractures (OTA type 42) were
classified as follows: 1 A1, 2 A2, 1 B1, 1 B3, 1 C1, 3 C2, and 7 C3 fractures. The 19 combined fractures (OTA types 41 and 42) were classified as follows: 3 A2, 2 A3, 1 B3, 1 C1, 3 C2 proximal segment (OTA type 41) fractures and 9 C3 fractures combined with 1 A1, 5 A2, 1 A3, 5 B2, 1 B3, 2 C1, 1 C2, and 3 C3 shaft segment fractures (OTA type 42). There were thus 49 articular injuries in total. Fifty-five fractures were closed, and 22 were open. According to the Gustilo-Anderson classi- fication, there were 1 type I, 5 type II, 8 type IIIA, 7 type IIIB, and 1 type IIIC fractures.
Internal fixation using the LISS was performed at an av- erage of 7.1 days (range: 0–29 days) after the injury. Twenty- two fractures were operated on within the first 24 hours. In the other 55 fractures treated after 24 hours, a spanning external fixator was used for initial provisional stabilization in 30 frac- tures. The study protocol called for recording of total surgical time as well as the time it took for the insertion of the LISS fixator and all the locking screws. Because of the recognition of all the articular injury patterns and the variable time it took for periarticular fixation, the relevant data point was LISS in- sertion time only. No specific protocol for the use of a tourni- quet was established; therefore, its use was at the surgeon’s discretion. It was used most often for articular reconstruction, although specific data on exactly what in what portion of the case it was used were not recorded.
There are 3 length choices for implants in the tibia: 5-, 9-, and 13-hole fixators. The implants used for the fractures in this series included 6 5-hole, 43 9-hole, and 28 13-hole fixators.
The mean number of locking screws used in the proximal ar- ticular segment was 4.9 (range: 3–7 screws), and the mean number of screws used in the distal segment was 4.8 (range:
2–6 screws). In 53 patients, adjunctive implants were used for periarticular fixation, which included 6 plates (small-fragment plates), 1 K-wire, and articular lag screws in 49 fractures. Al- lograft bone grafting was performed in 9 cases of tibial plateau fractures, where voids from depressed plateau fracture frag- ments had to be filled and buttressed. Calcium phosphate ce- ment was used in 1 such case. Thus, bone filler of some variety was used in 10 of 49 cases associated with articular injury. For open injuries, cefazolin and gentamicin were administered in- travenously before debridement of the open wound, and cefa- zolin was then administered intravenously for 48 hours after debridement. For closed injuries, cefazolin was administered intravenously before surgery and for 48 hours after surgery. In general, open fractures were treated with initial irrigation and debridement within 12 hours of injury, with placement of a spanning external fixator and wound closure if possible. De- finitive fixation then ensued at approximately 2 weeks after the injury. If wound closure was not possible, a repeat irrigation and debridement procedure was performed at 2 to 3 days after the injury, followed by fixation, with rotational flap coverage performed at that time. Patients were generally placed on enoxaparin administered subcutaneously for thrombosis pro-
phylaxis, beginning on postoperative day 1 and continued at least until the patient was discharged.
After surgery, all patients were treated with immediate range of motion in a CPM machine until discharge from the hospital. The patients were generally followed at 2, 6, and 12 weeks as well as at 6-month intervals thereafter. Although the follow-up times were variable, the surgeons’ conventional postoperative plan was to begin partial weight bearing with crutches after the 6-week visit and full weight bearing after the 12-week visit. Modifications to this regimen were made based on fracture pattern, articular involvement, bone quality, and
stability. Radiographic assessment of the fractures immedi- ately after surgery included a goniometric measurement of alignment, although long leg films were not always used for this purpose. In most cases, no comparison films of the contra- lateral side were made. Therefore, in assessing excess varus or valgus, an average of 4° of varus of the proximal tibial plateau was considered “normal.” During follow-up patient visits, spe- cific attention was paid to loss of fixation or varus collapse as well as to consolidation of fracture lines when assessing the radiographs. A clinical correlation for healing was also per- formed with varus and valgus stress examination at the fracture FIGURE 1.Radiographs are shown for the case of a 42-year-old man who presented after a motor vehicle collision. He sustained a closed tibia plateau fracture with diaphyseal extension and an ipsilateral proximal fibula fracture. Initially, the patient underwent a 4-compartment fasciotomy, fixation of the fibula, and spanning external fixator placement across the knee. A, Anterior-posterior and lateral injury radiographs depicting the bicondylar OTA type 41-C3.1 fracture (Schatzker type VI). B, Intraoperative anterior- posterior C-arm spot showing a close-up of the articular reconstruction. C, Anterior-posterior postoperative radiographs demon- strating restoration of length, alignment, and rotation. D, Anterior-posterior and lateral radiographs 10 months after surgery demonstrating a healed fracture.
site as well as an office trial of weight bearing to check for pain.
RESULTS Time to Full Weight Bearing
The mean time to allowance of full weight bearing was 12.6 weeks (range: 6–21 weeks). Forty-eight patients were clinically healed when full weight bearing commenced, and all but 2 eventually healed.
Range of Motion
The study group attained a mean arc of knee motion at last follow-up of 1° (range: 0° to −10°) to 122° (range: 80°–
150°). Sixty-nine patients were able to fully extend their knee, whereas in 8 other patients, there was an average extension lag of 6°. The range of motion for the extra-articular injuries was a mean of 0° to 126°, and for the intra-articular fractures, the range of motion was 1° to 122°, which was not significantly different (Studentttest,P= 0.28). Two patients in the series who had concomitant ipsilateral Gustilo type IIIA open frac- tures of the distal femur (OTA type 32/33-C3) required quad-
ricepsplasty for joint ankylosis and ectopic bone removal.
These operations were performed at 4 and 8 months after sur- gery and resulted in a final range of motion of 3° to 80° and 0°
to 110°.
Major Complications
Seventy (91%) of 77 fractures healed without major complications. Six of the 7 major complications required sec- ondary surgical procedures, including 2 proximal losses of fixation, 2 nonunions, and 2 deep infections. The seventh ma- jor complication was a deep peroneal nerve injury sustained at the time of surgery. The patient had weakness of the extensor hallucis (1/5 motor strength) and sensory deficit in the first dorsal web space. Details of the major complications are as follows.
During the early postoperative period, 2 patients re- quired reoperation for loss of fixation in the proximal frag- ment. In 1 such case, the patient was a 6-ft 7-in, 410-lb, men- tally retarded individual who walked on his leg within 2 weeks of surgery. This action resulted in catastrophic fixation failure in which bone protruded through a 24-cm laceration that was an extension of the original incision. After his subsequent re- FIGURE 2.Intraoperative photographs of a proximal tibia shaft fracture for which a 13-hole Less Invasive Stabilization System (LISS) fixator was used. A, Laterally based image of the lower extremity after insertion of the LISS fixator and placement of screws through the insertion guide. Note the 3 centimeter distal lateral incision for an open percutaneous screw placement. B, The proximal anterolateral incision is shown after fixation and removal of the insertion handle. C, Postoperative lateral image depicting the proximal approach and distal stab incisions after closure.
fixation procedure, he was placed in a knee immobilizer and restricted with bed to chair precautions for 6 weeks. This pa- tient went on to heal with a final range of knee flexion of 10° to 80° at 7 months after surgery. The second patient who experi- enced failure of proximal fixation had an anterior translational deformity of the proximal fragment relative to the distal frag- ment as well as a flexion deformity of 10°. The patient recog- nized decreasing motion and pain in the region of the tibia tu- bercle within 10 days of surgery. This patient’s surgery was revised, and he went on to heal without adverse consequences 10 weeks after the second surgery.
The 2 nonunions described were associated with open fractures. One was a Gustilo type IIIA fracture with associated partial bone loss (50% of circumference), in which the surgeon performed an elective autograft bone grafting procedure 4 weeks after surgery. This went on to a nonunion that required 1 further autograft and tension band plating using a conven- tional large-fragment plate. A conventional large-fragment plate was chosen to enable fracture site compression, because the biomechanics of the LISS internal fixator allow some mi- cromotion at that site. The other patient with a nonunion had a Gustilo type IIIB open fracture, a segmental tibia variant asso- ciated with a compartment syndrome, as well as a complete tibial nerve axonotmesis. The patient was a 17-year-old boy whose injury never healed, and the patient elected to undergo a high below-knee amputation at 10 months after surgery be- cause of a painful dystrophic leg and chronically draining neu- rotrophic pressure ulcers—a manifestation of the tibial nerve dysfunction. Although the possibility of reconstructive proce- dures was discussed with the patient, no such procedures were performed before amputation. An additional patient in the se- ries underwent an above-knee amputation for severe neuro- genic pain from a lumbosacral plexus injury related to a severe pelvic fracture. The patient also had associated bilateral ace- tabular fractures and a distal femur fracture. His tibial fracture healed without complication.
The 2 delayed infections presented long after the initial surgery (12 and 14 months), and in both cases, bony union was complete. Both cases responded to serial irrigation and de- bridement and hardware removal, followed by adjunctive antibiotics. Culture results revealed methicillin-resistant Staphylococcus aureus(MRSA) in 1 case, and “no growth”
in the other. One of the 2 infections occurred in a patient whose initial injury was a Gustilo type IIIB ipsilateral OTA type 41/42 plateau and shaft fracture, and the other occurred in a closed OTA type 41C3 fracture. The patients had no symp- toms leading up to the infection and had an initially uneventful clinical course as well as an eventually uneventful clinical course.
There were 2 postoperative nerve palsies. The first was likely iatrogenic, an injury to the deep peroneal nerve, thought in retrospect to result from the distal percutaneous placement of screws through a 13-hole fixator. This patient’s nerve palsy
improved from grade 0/5 to grade 3/5 muscle strength after 2 years. The second patient with a nerve palsy (not classified as a major complication) had global dysesthesias involving the tibial and peroneal nerve distribution, which were thought to be related to a tourniquet used during surgery. This patient’s palsy completely resolved.
Minor Complications and Reoperations
Other than the 2 patients with early postoperative failed fixation, there were no cases of late loss of reduction and, spe- cifically, no instances of late varus collapse. One patient had an acute superficial infection, which occurred in an open fracture wound (type II) distant from the LISS insertion site.
This patient responded to a single irrigation and debride- ment procedure and a course of oral antibiotics. There were no other cases of superficial or deep infections in the acute setting, although there were 3 cases of postoperative draining seroma, all of which occurred in patients with open fractures (1 type IIIA and 2 type IIIB fractures). These 3 patients were treated with early irrigation and debridement within 2 weeks of surgery, followed by a period of immobilization. Cultures taken during surgery in all 3 cases were negative. Perioperative antibiotics were given after cultures were taken in these 3 cases.
Four fixators (5%) were removed for the indication of hardware irritation at 6, 9, 12, and 14 months after the initial fixation. Additionally, 2 LISS fixators required removal at the time of their nonunion surgery, and 2 were removed for treat- ment of deep delayed infection. Finally, 2 LISS fixators were removed for the purpose of performing a high tibial osteotomy as described elsewhere in this section. In the 10 LISS implants that required removal, cold welding was recognized in 1 case at the interface of 4 of the 11 locking screws, all of which were fixed to the diaphyseal segment. The surgeon opted to leave the 4 cold-welded screws and the plate in, because the patient’s only symptoms resulted from 2 prominent periarticular screw tips on the medial side around the pes anserine bursa. The pa- tient’s hardware-related symptoms did, in fact, entirely resolve after surgery. Overall, of the 94 LISS locking screws in the 10 LISS fixators that required removal, only 4 screws in 1 case demonstrated cold welding.
In 2 patients, the LISS fixator was removed for the pur- pose of performing a high tibial osteotomy at 26 months and 10 months after surgery. In both of these patients, the goal was to shift the mechanical axis more medially and to offload the lat- eral tibial compartment. One of the patients had excessive genu valgus (8°), and the other patient had severe posttrau- matic arthritis of the lateral compartment with accompanying genu valgus (4°). Both of these osteotomies healed unevent- fully.
Two other minor complications occurred in the 2 cases requiring quadricepsplasties as mentioned previously.
Malreductions
Postoperative malalignment occurred in a total of 13 cases (17%), although it was believed to be of clinical signifi- cance in only 3 cases. Specifically, in 6 cases, there was a co- ronal plane malreduction (varus/valgus), which was combined with a rotational deformity in 1 case. In 7 cases, there was a sagittal plane malreduction (flexion/extension). There was no shortening detected in any case. In detail, the 6 cases of coronal plane postoperative deformity included valgus malalignment in 4 cases (3°–5° in 3 cases and 6°–10° in 1 case) and varus malalignment in 2 cases (3°–5°). With regard to the 7 cases of sagittal plane deformity, 6 cases demonstrated flexion at the fracture site (6°–10° in 5 cases and 15° in 1 case). A single patient demonstrated hyperextension between 6° and 10° at the proximal fracture site. Three of the malreductions were thought by the patients or examiners to be clinically significant (6°–10° valgus malreduction [eventual tibial osteotomy], 5°
varus malreduction [revised], and 15° flexion [revised]). In all 3 cases, the angulation problems were thought to be technical intraoperative assessment errors. In the latter 2 cases, the fixa- tion was revised in the ensuing days. In the first case, revision surgery was not thought to be appropriate in an unstable polytrauma patient. The patient underwent a tibial osteotomy at 10 months. Articular malreductions were seen in 2 patients, both with a 2-mm step-off in the lateral tibial plateau.
Surgical Time
The average time for placement of the LISS implants was 54 minutes (range: 30–94 minutes), which included the time from initial insertion to placement of the last self-tapping screw. These data were collected from 60 of the surgeries in the study group. A surgical technique learning curve is re- flected in the time differences for insertion of the LISS im- plants between the first 20 patients (mean = 64 minutes), the second 20 patients (mean = 55 minutes), and the third 20 pa- tients (mean = 42 minutes). An analysis of variance (ANOVA) supplemented by the post-hoc Tukey test for pairwise com- parisons revealed significant differences between the second and third 20 patients (P< 0.05) and highly significant differ- ences between the first and third 20 patients (P< 0.001)
DISCUSSION
Preliminary results from the first published case series of 54 patients treated with a LISS for bicondylar proximal tibial plateau and proximal tibial shaft fractures showed a high rate of union (97%), an acceptable rate of infection (4%), and stable fixation preventing late varus collapse, which is similar to the findings of other small case series in the literature.4–6Our ini- tial report4focused mainly on surgical technique, including the approach and nuances to different fracture patterns, whereas the current study is a more comprehensive examination of the operative and clinical data in an expanded case series. This
report includes those patients as well as an additional 21 pa- tients and more closely examines their early clinical outcome.
At first glance, it may seem that the inclusion of bicon- dylar tibia plateau fractures and proximal third tibia fractures in the same cohort is irrational. This is not meant to be a func- tional outcome study of certain fracture types, however, but rather an assessment of the utility and safety of a technique, certain clinical outcome parameters, and the ability of an im- plant to maintain reduction and fixation in the face of aggres- sive rehabilitation, high deforming forces, and a compromised soft tissue envelope, all of which have made fractures any- where in the proximal tibia historically challenging to treat.
Furthermore, the common denominator in all the fractures in this study is a dissociation of the articular surface from the diaphysis as well as involvement of the medial and lateral col- umns of the proximal tibia.
A high proportion of injuries in this series were severe, including 39% that were OTA type 41-C3 injuries, 29% open fractures that were nearly all Gustilo type IIIA and type IIIB fractures, 25% that were ipsilateral OTA type 41 and 42 frac- tures, and 14% that included floating knee variants. Thus, this series may represent a skewed view not typical for every insti- tution and may provide a more guarded impression of the treat- ment of such injuries using the LISS. In this light, it would seem that the mean range of motion (1°–122°) at final follow- up as well as the major complication rate of 9% shows promise for the methodology.
It is recognized that time to fracture union is not specifi- cally reported in our data. It is generally agreed that this pa- rameter is difficult to assess and includes clinical and radio- graphic variables for which there is no consensus. As a result of our prior experience with locked-angle implants in the fe- mur (LISS) and forearm (PC Fix), we took a more aggressive approach to rehabilitation, including immediate passive and active range of motion as tolerated as well as advancing weight bearing starting at 6 weeks. Although it is reported here that the mean time for allowance of full weight bearing was 12.6 weeks after surgery, given the expanded time intervals between office visits, we cannot definitively say anything accurately about time to clinical or radiographic healing. It is our clinical im- pression, however, that progressive functional recovery, in- cluding ambulation, may be more relevant than the radio- graphic contact of a certain number of cortices.
Possible disadvantages of using the LISS include sur- geon unfamiliarity with closed reduction techniques and fix- ator application. This methodology is unconventional, and the technique requires that a closed reduction be accomplished be- fore implant application and fixation to the bone. Although the closed reduction can be accomplished using any combination of manual traction, well-placed bumps, bone distractors, and approximation devices (eg, “whirlybirds”) included in the LISS tray, these tactics are at first unfamiliar and require prac- tice. Supporting this notion of a learning curve was the time it
took to do the implantation of the locked LISS plates in the first 20 patients recorded (64 minutes) and the last 20 patients (42 minutes). The learning curve is further underscored by exami- nation of the common malalignments in this series. There were 6 cases of coronal plane postoperative deformities, although only 1 had valgus malalignment more than 5°, and varus mal- alignment in 2 cases (range: 3°–5°). The 7 cases of sagittal plane malalignment were more significant, with 6 of these cases having a flexion deformity at the fracture site (5°–10° in 5 cases and 15° in 1 case). Based on this experience, the au- thors believe that good intraoperative radiographs are needed to decrease the incidence of malreduction when learning the technique. Radiographs on a large flat plate before placement of all the LISS screws (provisional reduction radiographs) are important in reducing malalignment errors. At the least, fluo- roscopy should be used in a way to increase the field of view before screw placement. The authors recommend that strategic bumps be used during the case. These should rest with the apex just distal to the popliteal fossa, supporting the distal fragment, to help avoid relative anterior translation of the proximal frag- ment as a result of the pull of the quadriceps. For the same reason, more than 15° of knee flexion should be avoided. Tech- niques for successful implantation of the tibia LISS, including many technical tricks for reduction, have been previously de- scribed.4
Another possible disadvantage of percutaneous tech- niques in the distal lateral leg is the risk of injury to neurovas- cular structures. We reported 1 neurologic injury in the study group. A single deep peroneal nerve palsy would at first seem like an unusually low incidence, given the finding of a 27%
(15% deep neurovascular bundle and 12% superficial peroneal nerve) incidence reported by Kregor et al7in an anatomical dissection study of cadaver legs implanted with 13-hole LISS fixators. Twenty-eight 13-hole fixators were used in the cur- rent study; thus, we believe the discrepancy may be explained by the open incision that we advocate for the placement of distal screws (Fig. 2). Although the authors have advocated the mini-open distal technique to ensure that the fixator is placed exactly centered lateral, it is likely that this also explains the low rate of neurovascular injuries in this series.
The operative treatment of proximal tibia fractures, with or without intra-articular involvement, is associated with well- described patterns of failure, soft tissue complications, and in- fection.1–3,8,9For bicondylar fixation, there is really only 1 ar- ticle with high complication rates1; though it is commonly taught that extensile and combined approaches are associated with a high rate of wound complications, for bicondylar fixa- tion, there is really only 1 article demonstrating high compli- cation rates.1The LISS is akin to an internal fixator, which provides comparable stability to double-plating constructs in a biomechanical evaluation by Goesling et al.10Zlowodzki et al9 have shown that the LISS fixator for treatment of distal femur fractures, which has similar material and design characteristics
as the tibial LISS fixator, provides superior fixation in osteo- porotic bone compared with the blade plate and retrograde IM nail. This series has demonstrated that its use prevents varus collapse in bicondylar tibial plateau fractures.
In an evidence-based systematic review of 17 case series evaluating plates, nails, and external fixators for the operative treatment of extra-articular proximal tibial fractures, Bhandari et al11reported significantly lower infection rates for IM nail- ing (2.5%) compared with plating (14%) and external fixation (8%). Malunion rates were higher for IM nailing (20%) com- pared with plating (10%) and external fixation (4%), how- ever.11Infection and nonunion rates associated with circular wire or hybrid external fixation of complex tibial plateau frac- tures were reported to range from 0% to 10% (infection) and from 0% to 2% (nonunion), with pin tract infection rates of up to 33%.12–15Modern less-invasive plating methods of com- plex tibial plateau fractures yielded infection rates of 4% to 11% and nonunion rates of 0% to 2%.9,16,19
The surgeon must carefully assess the articular injury associated with a tibial plateau fracture. It must be understood that the proximal screws of the LISS offer no compression of the articular surface. Understanding this, the role of the LISS is extremely limited, if not obsolete, for Schatzker type I to IV tibial plateau variants. The approach, reduction, and fixation for the articular injury should be performed before LISS appli- cation. No compromise in the visualization of the articular sur- face should be entertained simply because a submuscular tech- nique is being used. The LISS may be thought of an “internal fixator” that connects the articular block with the diaphysis.
Another word of caution is merited regarding the timing of definitive operative intervention, particularly for the high- energy, bicondylar, tibial plateau fracture. Although it is true that smaller incisions may be used, this does not obviate the need for patience to allow the soft tissue swelling to subside after injury. In this series, the average time for LISS implanta- tion was 7 days after the injury, and it was performed up to 29 days after the injury. A spanning external fixator was useful for stabilization of these fractures. We believe that this concept is as important as the LISS methodology for avoidance of soft tissue complications and infection. The LISS methodology for proximal tibial fractures encompasses a surgical technique of submuscular placement of the fixator and the biomechanical advantage of fixed-angle screws. Its utilization in this series for complex bicondylar tibial plateau fractures and proximal tibial shaft fractures is encouraging, with 97% maintenance of fixation, a 97% union rate, and a 4% (superficial or deep) in- fection rate.
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