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Double Oblique Osteotomy: A Technique for Correction of Posttraumatic Deformities of the Distal Femur

Miranda, Michael A. MD*; DeAngelis, Joseph P. MD†,‡; Canizares, George H. MD§; Mast, Jeffery W. MD

Author Information
Journal of Orthopaedic Trauma: February 2018 - Volume 32 - Issue - p S60-S65
doi: 10.1097/BOT.0000000000001090

Abstract

INTRODUCTION

Posttraumatic deformities of the distal femur constitute a challenging problem in orthopaedics, and their correction has received little attention in the literature.1–5 These deformities can develop following closed management, open reduction with internal fixation, or retrograde intramedullary nailing.6 The resultant malunion is typically multiplaner because of the muscular forces acting on the distal femur.2 Options for correction of the deformity include a single-stage osteotomy or an osteoplasty created over time.2,5,7–11 A single corrective osteotomy is limited in its capacity to completely correct a deformity that is present in multiple planes while simultaneously restoring ligamentous balance around the knee.1,7,9,10 Similarly, osteoplasty of the femur using a thin-wire fixator in the method of Ilizarov has significant associated complications including prolonged healing time and increased risk of infection.12 In attempting to address the limitations of the existing methods, this report describes a series of patients treated with a double oblique osteotomy technique developed by the senior author (J.W.M.), which allows for a single-stage correction of multiplane deformities of the distal femur.

MATERIALS AND METHODS

The clinical records and radiographs of all patients having undergone a double oblique osteotomy of the distal femur over a 10-year period (1994–2004) were reviewed. Twelve patients with posttraumatic, multiplane deformities of the femur were identified. Two patients were excluded, one because of the underlying bone disease (fibrous dysplasia) and the other because of the inadequate length of follow-up (7 months). There were 8 malunions, and the remaining 2 patients were diagnosed with a nonunion (Table 1). One nonunion was the consequence of primary closed management of the fracture and the other was the result of an attempted corrective osteotomy of a malunion. All 10 patients presented with a leg length discrepancy (LLD) and complaints related to pain, shortening, excessive bowing, or torsion. For those patients with pain as their primary complaint, all other potential causes were evaluated and excluded as the etiology of their complaints.

TABLE 1.
TABLE 1.:
Demographic and Procedural Characteristics

Radiograph Measurements

All patients were assessed using preoperative and postoperative plain x-rays of the knee and a standing full leg anterioposterior radiograph. Pre- and post-operative determination of the anatomic and mechanical axes was obtained using the full-length anterioposterior, weight-bearing films from the hip to the ankle of both the involved and uninvolved extremities.3,4 (Fig. 1) Leg lengths were evaluated using either computed tomography (CT) or a lower limb scanogram using the standard technique.3 The rotational deformity was determined either by clinical examination and/or CT scan studies of both femurs pre- and post-operatively.13 In 4 cases, use of the contralateral limb and a goniometer was the sole method of pre- and post-op rotational evaluation. Detailed preoperative planning was performed in all cases, and complete correction of the deformity was the goal in all but 1 case (JF).3,4 (Figs. 1, 2).

FIGURE 1.
FIGURE 1.:
The preoperative anterioposterior (A), lateral (B), and full-length, weight-bearing (C) radiograph from patient KS (Table 1). The full-length radiograph illustrates the derangement of the mechanical axis and allows for precise operative planning.
FIGURE 2.
FIGURE 2.:
The preoperative anterioposterior (A) and lateral (B) radiographs from patient TK (Table 1) and the resultant preoperative plan (C and D).

The degree of deformity was assessed by measuring the mechanical tibiofemoral angle, the medial proximal tibia angle, the mechanical lateral distal femoral angle, and the knee joint line convergence angle preoperatively and postoperatively.11 There were no joint contractures to affect the radiographic measurements.

Operative Technique

With the patient positioned supine and a bump placed under the hip of the affected limb, a standard direct lateral approach to the distal femur is performed.14 A tourniquet is not applied to the extremity. The dissection was completed to the level of the periosteum with careful handling of the soft tissues and maintenance of hemostasis. Once the exposure is complete, the angled blade plate is used according to the previously described technique.15 Once satisfactorily chisel position is identified, consistent with the preoperative plan, it is introduced into the distal femoral metaphysis and left in situ. Using intraoperative fluoroscopy, Kirschner wires were placed along the line of the planned osteotomies. A total of 3 cuts are made: 2 oblique cuts that create the retained wedge, which is ultimately medialized for length, and a third cut that creates a small wedge or hemiwedge that is resected as a closing wedge osteotomy to correct the deformity in accordance with the preoperative plan in the coronal and sagittal planes (Figs. 2C–D). The osteotomy cuts are incompletely made with a sagittal saw. The chisel is then removed, and a plate is applied for rigid fixation. Osteotomies are then completed with an osteotome.

Any rotational deformity, if present, can be corrected at this point through both osteotomies if present. This is accomplished by placing a Kirshner wire in the proximal and distal fragments in a parallel plane. The distal fragment is rotated the documented difference as determined by the CT while a Verbrruge clamp maintains stability of the construct.

At this point, a tensioner-distractor (Depuy Synthes, Paoli, PA) is applied to the proximal end of the plate. Initially, the construct is distracted, and the large osteotomized wedge is translated medially using 4.5-mm cortical screws placed through the plate (Fig. 2D). These screws are prevented from backing out by placing a nut medial to the plate. Holding the nut while advancing the screw allowed for translation of the bone wedge medially without lateral migration. By virtue of its obliquity, the medial translation of the wedge osteotomy lengthens the femur. Once all planes were corrected, the tensioner-distractor is then reversed, and the osteotomies were compressed. The plate was fixed proximally, and the bone graft is applied when necessary. Somatosensory evoked potentials can be monitored intraoperatively and were in all patients during limb lengthening.

Postoperatively, patient activity is limited to foot-flat, touch-down weight-bearing until callus is seen on 1 view then advanced. No splints or braces were applied, as active range of motion was encouraged. Initially, continuous passive motion was used in the immediate postoperative period. However, this modality was discarded early on because of lack of perceived effectiveness.

RESULTS

Five males and 5 females, all with unilateral injuries, were available for study. The mean interval between the index fracture repair and double oblique osteotomy was 78 months (range 9–194 months). The average length of follow-up was 26 months (range 18.5–42 months). All 20 osteotomies went on to achieve union with 1 patient requiring (KS, Table 2) repeat bone grafting. In 7 patients, the iliac crest bone graft was used at the time of surgery. A 95-degree angled blade plate (Depuy Synthes) was used in 8 patients (Figs. 3A–B); a dynamic condylar plate (Depuy Synthes) was used as a waveplate16 in 1 patient, and a condylar buttress plate (Figs. 4A–B) (Depuy Synthes) was used in 1 patient. Two patients had a tibial osteotomy at the time of the double oblique femoral osteotomies to correct an oblique joint line. Average time to full weight-bearing was 4.3 months (range 2.5–9 months) (Table 1).

TABLE 2.
TABLE 2.:
Post-operative Limb Characteristics
FIGURE 3.
FIGURE 3.:
The 10-month postoperative anterioposterior (A) and lateral (B) radiographs in patient from Figure 3 (TK, Tables 1 and 2) show the corrected and healed malunion.
FIGURE 4.
FIGURE 4.:
The 8-month postoperative anterioposterior (A) and full-length scanogram (B) in patient from Figs. 1, 2 (KS, Tables 1 and 2) show healing for the malunion and the alignment correction.

All patients had length discrepancies (Table 2). The average LLD was 2.9 cm (range 1–7 cm). The average leg length correction was 1.6 cm (0.4–2.6 cm) or 58% of the original LLD. To secure union, the osteotomies in the 2 patients with nonunions were placed in compression. If these 2 cases are excluded, the average correction is 1.9 cm (1.0–2.6 cm) or 63% of the original LLD. Both these values include a 2.6-mm correction of a 7-cm LLD in which full correction was not the goal (JF).

In addition to the LLD, within this study, there were 4 single-plane deformities (varus), 2 bi-planar deformities (varus and flexion), and 4 tri-planar deformities (varus, flexion, and rotation). Average preoperative deformity was 12 degrees of varus angulation (range 0–20 degrees); 14 degrees of flexion (range 0–18 degrees); and 26 degrees of rotational deformation (range of 45 degrees external rotation to 36 degrees of internal rotation.) The average correction in the coronal plane was 12 degrees (range of 4–20 degrees). Three of 5 flexion deformities were corrected to within 5 degrees of normal (Figs. 3, 4). Residual flexion deformity was less than 10 degrees in all cases. Rotational deformities were corrected to within 5 degrees of neutral in all cases. On average, total range of motion increased from 106 to 115 degrees postoperatively (Table 2).

In this series, there were 3 complications. One patient required additional bone graft to achieve union and a second patient complained of local discomfort from prominence of the angled blade plate. The plate was removed 8 months postoperatively with resolution of the patient's symptoms. One patient who underwent simultaneous tibial and femoral osteotomies (LB, Tables 1 and 2) sustained a sensory deficit in the distribution of the saphenous nerve; however, this deficit resolved during the follow-up period.

DISCUSSION

Anatomic reduction is rare in complex fractures of the distal femur.6 In type C3 supracondylar femur fractures,17 malunion is common as the exaggeration of the femur's normal anterolateral bow creates a complex, multiplanar deformity.6 However, the correction of distal femoral malunions has received scant attention in the literature.2,3 Yadav described a double oblique diaphyseal osteotomy for lengthening short limbs in patients with infectious, congenital, and posttraumatic etiologies.18 Postoperative stabilization was achieved with external fixation in patients younger than 4 years and with traction in patients older than 4 years. In 2000, Lonner described a technique of femoral osteotomy in conjunction with total knee arthroplasty in a series of patients with midshaft and distal femur deformities.2 Union was achieved in 9 of their 10 fracture malunion patients. The 1 nonunion persisted, despite subsequent bone grafting and 3 other patients required a return trip to the operating room: 1 required hardware removal, whereas 2 others required knee manipulations.

Other techniques are available for correction of supracondylar malunions. They include a medial opening-wedge osteotomy, a lateral wedge closing osteotomy, an oblique osteotomy, and an osteoplasty in the method of Ilizarov.5,11,19 Several disadvantages exist in the use of a medial opening-wedge osteotomy. For example, unlike the lateral approach, a medial approach places the femoral nerve and vessels at risk. In addition, it is difficult to achieve a normal mechanical axis using a medial wedge osteotomy because it does not allow for translation of the femoral condyles into the weight-bearing axis. Last, a medial approach allows for limited fixation in the distal metaphysis.

A lateral closing-wedge osteotomy of the distal femur permits more points of fixation. A lateral closing-wedge osteotomy yields a stable construct; however, length is typically lost not gained. Oblique osteotomies can be in the sagittal plane (Figs. 5A–C) or, as in the method of Sangeorzan et al,19 in a plane determined by mathematical computation. The advantage of a sagittal plane osteotomy is the ability to correct deformities in the coronal plane (varus and valgus) and gain length in a simple fashion. Unfortunately, with this technique, there is no simple way to address malrotation. The oblique osteotomy of Sangeorzan et al19 is ingenious and has great capacity for correction. However, it is a difficult to compute the desired angle, and an easy miscalculation can create a maloriented cutting-plane.

FIGURE 5.
FIGURE 5.:
Example of a sagittal plane osteotomy: (A) preoperative anterioposterior; (B) the plan; and (C) coronal plane correction.

Osteoplasty in the method of Ilizarov is a powerful technique for the correction of malunions. However, there are many associated difficulties including muscle contractures, joint subluxation, axial deviation, neurologic injury, vascular injury, premature consolidation, delayed consolidation, nonunion, pin site problems, and hardware failure.12 In the femur, the Ilizarov frame is poorly tolerated because of the large thigh soft tissue envelope and, as a result, there is a high rate of pin site complications. According to Heirholzer, internal fixation is the preferred method of stabilization for femoral posttraumatic deformity correction.1 Other methods3,9,10 have been described for correction of femoral malunions, but these techniques are described primarily for diaphyseal malunions.3,9,10

In the work by Heirholzer, if a correction is performed above or below the apex of a deformity, an additional translational maneuver is required to normalize the alignment of the limb.1 Thus, it is necessary to create a deformity to correct a deformity. Similarly, for patients with pathologic bowing of the femur, Paley and Tetsworth promote using multiple osteotomies for correction of the mechanical axis.11 Consistent with these investigators, in our series, a 2-level osteotomy was used to correct multiplane deformities in malunited and nonunited femurs. One hundred percent union was achieved with 1 patient requiring reoperation with bone grafting. The average frontal plane correction was 12 degrees, and all patients were within 5 degrees of neutral. A tendency toward incomplete correction in the sagittal plane was appreciated, but the final results were all within acceptable limits. All patients had an initial LLD and on average, excluding the 2 patients with a nonunion, 63% of the LLD was corrected, which included a 2.6-cm correction of a 7-cm deficit. All rotational abnormalities were corrected satisfactorily. There were no infections, no permanent neurovascular complications, and no hardware failures.

The authors recognize that this study has a number of limitations. This series of patients is quite small. However, the patient numbers in this investigation is consistent with those from previous studies on this topic. In addition, this is a retrospective case series, which by definition has all the potential investigator bias and data reporting limitations in this type of study. However, the patients were carefully selected for this procedure, and their records and associated data were carefully maintained. Furthermore, there was no defined patient outcome measure. Nonetheless, bony union, deformity correction, and the total arc of joint motion were felt to be adequate objective treatment measures.

In conclusion, the double oblique osteotomy, while technically demanding, is a reliable technique for the correction of multiplane deformities of the distal femur. Although there were 2 patients requiring a secondary operative intervention, these were minor reoperations (bone grafting and hardware removal), which did not detract from the overall results. The degree of correction achieved with a 95% union rate at the initial surgery is encouraging and merits additional investigation.

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Keywords:

malunion; femur; osteotomy; internal fixation

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