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Three-year Results of Proximal Tibia Fractures Treated with the LISS

Boldin, Christian; Fankhauser, Florian; Hofer, Herwig Peter; Szyszkowitz, Rudolf

Clinical Orthopaedics and Related Research: April 2006 - Volume 445 - Issue - p 222-229
doi: 10.1097/01.blo.0000203467.58431.a0
SECTION II: ORIGINAL ARTICLES: Trauma
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Proximal tibia fractures present a difficult treatment challenge with historically high complication rates. In a prospective study, we asked whether the Less Invasive Stabilization System (LISS) plate can adequately treat extraarticular and complex intraarticular proximal tibia fractures and provide low complication rates and acceptable long-term functional outcomes. We prospectively observed 25 patients with 26 proximal tibia fractures (AO type A2, A3, C1, C2, or C3) treated with the LISS. Consecutive 3-year followup included radiographs and clinical examinations using Knee Society scores and Hospital for Special Surgery scores for extraarticular and intraarticular fractures. No loss of reduction occurred in patients with extraarticular fractures, whereas varus malalignment occurred in one patient with an intraarticular fracture. Two patients with AO 41 C 3.3 fractures had severe knee arthrosis develop and had total knee replacements. The mean Knee Society scores and final average Hospital for Special Surgery scores were similar for extraarticular and intraarticular fractures. Complications related to the surgery included one delayed union and implant removal in two patients. The LISS provided stable fixation of extraarticular and intraarticular proximal tibia fractures and good functional outcomes with a low complication rate. In complex articular fractures additional screws should be used.

Level of Evidence: Therapeutic study, Level II (lesser quality randomized controlled trial [eg, < 80% followup, no blinding, or improper randomization]). See the Guidelines for Authors for a complete description of levels of evidence.

From the Department of Trauma Surgery, Medical University, Graz, Austria. Each author certifies that he or she has no commercial associations (eg, consultancies, stock ownership, equity interest, patent/licensing arrangements, etc.) that might pose a conflict of interest in connection with the submitted article.

Received: June 2, 2005; Revised: October 7, 2005; Accepted: November 17, 2005

Each author certifies that his or her institution has waived approval for the human protocol for this investigation and that all investigations were conducted in conformity with ethical principles of research.

Correspondence to: Christian Boldin, MD, University of Traumatology Graz, Auenbruggerplatz 7a, A-8036 Graz, Austria. Phone: 43-316-385-2155; Fax: 43-316-385-3582; E-mail: christian.boldin@meduni-graz.at.

Treatment of extraarticular or intraarticular proximal tibia fractures remains problematic. Techniques of open reduction with internal fixation using traditional lateral plate and screw constructs offer little resistance to varus deformity. An additional medial plate18,28 or medial external fixation1,4,24-26,31,33,40-42 have been advocated to improve stability; but greater complication rates with additional plating (wound problems, deep infection) have been reported.8,37,43 Hybrid external fixation for these injuries is associated with malunion, pin tract complications, decreased knee range of motion, and poor patient satisfaction.10,21 Intramedullary nailing is not applicable in cases with intraarticular comminution, and this technique frequently has complications of valgus or apex anterior angulation and residual displacement at the fracture site.12,23

Less invasive internal fixation systems have theoretical advantages for treatment of proximal tibia fractures. Numerous studies of this approach for bicondylar proximal tibia plateau and proximal tibia shaft fractures have shown a high rate of union, stable fixation preventing late varus collapse, and a low rate of infection (Table 1).5,6,11,30,32,34,35 These studies are relatively short term and do not address the longer-term function of these patients.

TABLE 1

TABLE 1

We asked whether the LISS would provide adequate stabilization for extraarticular and intraarticular proximal tibia fractures with minimal complications and satisfactory longer-term functional outcome.

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MATERIALS AND METHODS

Between January 1999 and January 2002, we prospectively enrolled 25 consecutive patients with 26 proximal tibia fractures meeting our inclusion criteria at our Level I trauma center. Criteria for inclusion were adult patients with metaphyseal fractures of the proximal tibia (AO Type 41-A 2, 41-A 3, 41-C 1, 41-C 2, 41-C 3). All patients were treated with a laterally placed fixed-angle plate (Less Invasive Skeletal System or LISS; Synthes, Paoli, PA). AO Type 41-B fractures were excluded as several alternative treatment options exist. There were 14 women and 11 men. The average age of the patients was 62 years (range, 28-88 years). Patients sustained their fractures by the following mechanisms: motor vehicle collision (six); motor-cycle accident (one); bicycle versus motor vehicle (one); motor vehicle versus pedestrian (two); fall from a height greater than 2 m (five); fall from standing height (seven); and skiing (three). The minimum followup was 3 years (range, 36-41 months). One patient died 4 months after surgery from heart failure unrelated to the surgery, leaving 24 patients with 25 fractures for analysis.

The preoperative regimen involved anteroposterior (AP) and lateral knee radiographs obtained for all patients at the time of injury. Computed tomography (CT) was done in all patients with intraarticular fractures. Magnetic resonance imaging (MRI) scans of the knee were obtained for patients with suspected ligamentous injuries. According to the AO-classification, the patients were divided into two groups: Group 1 (extraarticular) included 10 Type 41-A fractures and Group 2 (intraarticular) included 16 Type 41-C (Fig 1). Eight of the fractures were open, three were Grade I (A 2.2, n = 1; C 3.1, n = 2), and five were Grade IIIA (A 3.2, n = 2; C 3.1, n = 3) according to the Gustilo and Anderson15 and Gustilo et al classifications.16 Ten patients sustained multiple injuries; four were ipsilateral and three were contralateral leg fractures (two contralateral fractures of the femur, one ankle fracture). Additionally, five patients with intraarticular fractures had major ligamentous injuries. The average time from the accident until surgery was 6.3 days (range, 0-20 days). Ten fractures were operated on within the first 24 hours. In the other 16 fractures treated after 24 hours, the fractured lower extremity was placed in a splint until wrinkled skin of the injured extremity was observed. One patient could not be operated on until 3 weeks after injury because of severe concomitant injuries. Preoperative antibiotics were administered intravenously in all patients.

Fig 1

Fig 1

The operative approach was via a 5 to 7 cm lateral skin incision on the tibia head for extraarticular fractures and was extended as needed to provide exposure of the articular surface for intraarticular fractures. A submeniscal arthrotomy was made for intraarticular fractures. The articular segment was reduced anatomically and held provisionally with Kirschner wires (K wires). In all cases of intraarticular fractures, interfragmentary lag screws (4.5-mm or 7.3-mm screws) were placed to stabilize the fragments before plate insertion. Care was taken to place these screws in positions that did not interfere with LISS screw placement. Then the proximal tibia fracture was reduced manually and temporarily fixed with K wires. The LISS plate was inserted submuscularly across the fracture site while maintaining slight contact to the bone. The position of the LISS on the lateral tibia shaft and tibia head was checked radiographically. The plate was secured temporarily with K wires. Mild malalignment in varus or valgus was corrected using the whirlybird or pull reduction instrument (Synthes). To ensure secure fixation, at least three to four screws were placed in each main fragment (Figs 2-5). The iliotibial fascia and wound were closed over a drain in standard fashion. Three of the five patients with ligament injuries had repair or reconstruction within 1 month of injury, but with a delay of at least 2 weeks to allow healing of soft tissues and the capsule before extensive arthroscopic procedures. In the other two patients, ACL-reconstruction was not performed because the patients were older than 60 years. No patient had primary bone grafting. We used 16, 5-hole and 10, 9-hole LISS plates and screws. The 13-hole fixator was not used in our patients.

Fig 2A

Fig 2A

Fig 3A

Fig 3A

Fig 4A

Fig 4A

Fig 5A

Fig 5A

Continuous passive motion (CPM) and individual physiotherapy with passive motion were started immediately after surgery. Patients with intraarticular fractures were kept toe-touch weight-bearing for 8 to 12 weeks, and patients with extraarticular fractures were kept toe-touch weightbearing for 6 weeks. Thereafter, weightbearing was advanced based on tolerance, radiographic evidence of fracture healing, and concomitant injuries.

At 3 years followup of both study groups, we recorded healing, fracture alignment, articular step-off, functional outcome, infections, and implant-related complications. Depending on allowed weightbearing, standing AP and lateral radiographs (plain films) were obtained postoperatively and after 4 weeks, 6 weeks, 8 weeks, 10 weeks, 12 weeks, 6 months, 1 year, 2 years, and 3 years. Radiographic healing was defined as bridging of three of four cortices. Fracture alignment was determined on each of these radiographs by making goniometric measurements as described by Freedman and Johnson.12 Normal frontal plane alignment was defined as 0°, and normal posterior tilt (apex anterior angulation) of the articular surface relative to the shaft in the sagittal plane was defined as 8°. Malalignment was defined as 5° or greater angular deformity. Specific attention was paid to loss of fixation or varus/valgus collapse. Rotational alignment was measured clinically at followups with normal rotation being equal to the contralateral side. All radiographic evaluations were done by two of the authors (CB, FF) reaching a consensus, not by an independent evaluator.

Functional outcome was measured for Group 1 and Group 2 using the Knee Society (KS) score19 and the Hospital for Special Surgery (HSS) score29 at follow-ups at 6 weeks, 12 weeks, 6 months, 1 year, 2 years, and 3 years.

Student's t test was used to compare the two groups (extraarticular and intraarticular fractures). A p value of 0.05 or less was considered statistically significant.

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RESULTS

All fractures in both groups healed except one. This patient had a Gustilo Type IIIA fracture (A 3.2) with associated partial bone loss and delayed bony healing. After an elective autograft bone grafting procedure 6 weeks after surgery, healing was achieved. Periosteal reaction was seen after a mean of 5.7 weeks (range, 4-7 weeks) and bony consolidation was evident after 11 weeks (range, 8-25 weeks).

Postoperative alignment was anatomic or near anatomic in all patients. Loss of reduction occurred in one patient from Group 2 who walked on his leg within 2 weeks of surgery although only partial weightbearing was allowed. The 4-week radiographs showed varus malalignment of 7°. The patient refused reoperation and the fracture healed 10 weeks after surgery (Figs 6-8).

Fig 6A

Fig 6A

Fig 7

Fig 7

Fig 8A

Fig 8A

In Group 2, the mean articular step-off was 0.7 mm (range, 0-5 mm). In two patients with AO Type 41-C 3.3 fractures, the articular step-off was greater than 3 mm (3.5 mm and 5 mm). Both had persistent moderate pain and limited walking associated with radiographic arthrosis. These two patients had total knee replacements 20 and 32 months after primary surgery.

Final KS scores and HSS scores were similar between Group 1 and Group 2 (Fig 9). For extraarticular fractures, the mean HSS score was 88, the mean knee score was 91, and the mean functional score was 93. For the intraarticular fractures, the mean HSS score was 74, the mean knee score was 80, and the mean functional score was 81. Both groups showed the highest outcome measures after 1 year. The greatest limitations in HSS score and KS score parameters were pain and function with walking. In Group 1, the range of flexion averaged 130° (range, 100°-140°), and in Group 2, the range of flexion averaged 117° (range, 75°-140°). The mean loss of extension was 1° (range, 0°-10°) for Group 1, and 3° (range, 0°-10°) for Group 2. No patient in either group had a deep or superficial infection.

Fig 9

Fig 9

In Group 2, one patient with a C 3.1 fracture had a compartment syndrome with incomplete peroneal nerve lesion because of primary trauma. At the 1-year followup, full neurologic recovery and function was noted. Also in Group 2, two patients with C 1.1 fractures had their LISS plates removed because of irritation of the iliotibial tract 15 and 21 month after primary surgery.

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DISCUSSION

Proximal tibia fractures may be extraarticular or intraarticular. Complications of treatment and associated injuries have led to several approaches with little consensus on optimal management. The LISS method of fracture fixation has the theoretical advantages of indirect fracture reduction and percutaneous submuscular implant placement. Although short-term data suggest reasonable complication rates, the data have been too limited to draw longer-term conclusions of either extraarticular or intraarticular proximal tibia fractures treated with the LISS. In three studies5,30,32 extraarticular and intraarticular proximal tibia fractures were analyzed concomitantly; two studies6,34 analyzed only the range of motion for extraarticular and intraarticular fractures as separate data sets; two studies11,35 were published concerning intraarticular fractures. We performed a prospective study to evaluate whether the LISS plate can adequately address extraarticular and complex intraarticular proximal tibia fractures and to determine the long-term functional outcome compared with historical published results.

Our study is limited by a small number of patients, but consecutive 3-year followup for 96% of the patients was available. Both groups showed the highest outcome measures after 1 year. The mean functional scores were lower for patients with intraarticular fractures, but statistically similar given the small numbers; these means included the two patients who had total knee arthroplasties for secondary arthrosis. A larger study may reveal differences between these two groups treated the same way, but generally, intraarticular fractures have less favorable outcomes. The average age of our cohort was older compared with patients in other studies, although 72% of our patients sustained their fractures by high-energy mechanisms.

In our study, the use of the LISS plate for treatment of extraarticular and intraarticular proximal tibia fractures resulted in good alignment. In the extraarticular fractures, no loss of reduction was seen. Early and midterm results with the LISS showed varus and valgus malalignment in 2% to 13% of patients and hyperflexion (apex anterior) deformity in 2% to 10% of patients, although extraarticular and intraarticular fracture types were mixed together in these study groups.5,6,30,32,34 Extraarticular proximal tibia fractures are associated with malalignment in the frontal and sagittal planes.12,17,20,38 Primary intraoperative malalignment occurs because of displacing muscle forces. Secondary displacement mainly is attributable to unstable fixation of the proximal fragment by the implant. Traditional lateral plating systems offer little resistance to varus deformity. Adjuvant medial neutralization plating has been advocated to increase stability in fracture patterns with metaphyseal comminution.28 Application of a medial plate requires a separate medial incision with the risk for injury of medial structures and of wound complications or unacceptable soft tissue compromise if applied via a single midline approach.27,36,43 Medial external fixation is another option to augment a lateral plate construct.4,31 Although these authors reported low malunion rates (2%), increasing rates of infection (17-33%) were noted. The use of intramedullary nailing techniques frequently is complicated by valgus (58%) or apex anterior angulation (22%) and residual displacement at the fracture site (59%).12,23 Proposed solutions include the use of blocking screws to functionally reduce the width of the medullary cavity and block transverse nail translation,14,20,22 altering the nail entry site,12 and altering the design of the nail.17 In an evidence-based systematic review of 17 case series evaluating plates, nails, and external fixators for operative treatment of extraarticular proximal tibia fractures, Bhandari et al reported greater malunion rates for intramedullary nailing (20%) compared with plating (10%) and external fixation (4%).2 Based on the results of our study, the fixed angle of the LISS construct seems to obviate the need for additional medial stabilization in cases of extraarticular proximal tibia fractures.

In our patients with intraarticular proximal tibia fractures, only one patient (6%) had varus malalignment of 7° because of walking on his leg with full weightbearing within 2 weeks after surgery. In two earlier studies11,35 of intraarticular fractures treated with the LISS, no malalignment was found, and other studies5,6,30,32,34 with patients with mixed extraarticular and intraarticular fractures showed varus and valgus malalignment in 2% to 13% and hyperflexion (apex anterior) deformity in 2% to 10%. Although much data are available regarding management and outcomes of tibia plateau fractures, a paucity of data exist that specifically addresses alignment after treatment of these fractures with traditional open reduction and internal fixation. Varus malalignment has been reported in 14% to 33% of patients.25,43 With minimal invasive percutaneous plate osteosynthesis techniques, loss of reduction was reported in 30% of the patients and delayed bone grafting was necessary in nearly ½ the patients.7 The incidence of malalignment in our patients can be compared with the results after treatment of patients with complex intraarticular proximal tibia fractures with external fixation and limited internal fixation. This technique has been associated with varus malalignment in 4% to 14% of patients.1,24-26,31,33,40-42

We think the LISS is indicated for treatment of intraarticular proximal tibia fractures, but the LISS plate alone is not sufficient for supporting comminuted or depressed articular fractures. The LISS provides two proximal screws that each angle slightly away from the articular surface (2-17 mm).13 This configuration supports the me-dial side from collapsing into varus, but it is difficult to get the screws proximal enough to support the subchondral bone. We always used additional screws for intraarticular fragment fixation. In all previous studies of treatment with the LISS, except one,30 additional screws11,32,34,35 or even plates5,6 have been used for intraarticular proximal tibia fractures.

Two patients in our series had early posttraumatic knee arthritis develop that required total knee replacements. These patients had severely comminuted intraarticular fracture components with primary cartilage damage. Given that only two patients with this complication had the greatest initial injury, we suspect the knee arthritis was more the result of severe primary injury rather than failure of treatment.

Functional outcome of proximal tibia fractures treated with LISS rarely is reported. Iinvestigators of only one study30 reported an average Lower Extremity Measure (LEM) score of 88 for only 16 of 38 patients. We used HSS scores and KS scores for both study groups. For extraarticular fractures, the mean HSS score was 88 with a mean knee score of 91 and functional score of 93. These results are comparable with results reported after external fixation with limited internal fixation. With this technique, an average HSS score of 90 was reported, although AO 41-A and 41-C fractures were mixed.42

In our patients with intraarticular fractures, the mean HSS score was 74, the mean knee score was 80, and the mean functional score was 81. Investigators of one study reported an HSS score of 81 in 14 patients with open tibial plateau factures treated by immediate open reduction and internal fixation.3 A mean knee score of 84 and functional score of 80 were reported for treatment of bicondylar tibia plateau fractures with external fixation,33 whereas a knee scores of 80 to 85 and 81 to 83 for function were found using external fixation with limited internal fixation.1,26 With this technique other authors reported average Iowa knee scores of 87 to 90.25,41 Therefore, our results with the LISS were comparable to scores reported using other approaches.

Complications in treatment of proximal tibia fractures are associated mostly in wound breakdown and deep infections. In this series, no infections occurred in patients with extraarticular or intraarticular fractures. In other studies, patients treated with LISS had low infection rates of 0% to 8%.5,6,11,30,32,34,35 Deep infection rates after open reduction and internal fixation have been reported to be approximately 20% (range, 0-87.5%).3,24,27,43 The use of external fixation and limited internal fixation have decreased the incidence of soft tissue breakdown up to 0%.1,4,21,24-26,31,33,40-42 However, septic arthritis has been found in 7% to 20% of patients because of pin tract infections (range, 5-100%).1,4,21,24-26,31,33,40-42 Collinge et al, in their study of minimally invasive techniques, had good results with no increase of infection or soft tissue damage.7

Additional percutaneous techniques in the distal leg may cause a risk of injury to neurovascular structures. Cole et al6 reported neurologic injury to the deep peroneal nerve in retrospect to result from the distal percutaneous placement of screws through a 13-hole LISS fixator. In an anatomic dissection study of cadaver legs implanted with 13-hole fixators, at holes 11 to 13 contact of the K wire with the peroneal nerve was found in 7% to 50%.9 Mini-open incision was recommended for placement of distal screws using a 13-hole internal fixator. We did not use the 13-hole internal fixator, perhaps explaining the absence of neurologic injuries.

The LISS provides stable fixation of extraarticular and intraarticular proximal tibia fractures with a low rate of complications and good functional outcome up to 3 years. In complex articular fractures additional screws should be used.

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