Anatomic and Clinical Findings

Anatomic findings have to be considered, such as the stage of osteoarthritis, analysis of the deformity and its reducibility, ligamentous status (frontal and sagittal laxity), and range of motion. Clinical findings are also essential, such as weight, age, level of activity, autonomy, general conditions (e.g., diabetes, rheumatoid arthritis, use of anticoagulants), and surgical history. The decision to perform a certain type of intervention is also sometimes influenced by geographic factors (e.g., an osteotomy is more frequently performed in regions close to the pole, whereas a prosthesis is more common in regions away from the poles), cultural factors (e.g., osteotomy more common in Asia and the Middle East, prosthetic surgery more common in English speaking countries), economic factors (e.g., UKA is not recognized and taught as a treatment option in some countries).

Patient Expectations

Patient satisfaction after an intervention is the result of the difference between the patient’s expectations (functional result expected), and functional result obtained. This means that vital information has to be given to the patient, which has to be adapted to the level of the patient’s understanding. If not done, this will sometimes lead to the patient’s misconceptions about the procedure and its results.

Concept of Functional Envelope Applied to Gonarthrosis

The x axis shown in Figure 95-1 represents the frequency of the applied forces or load and the y axis represents the intensity of the applied forces or load.²³ The surface under the curve defines the functional envelope of the knee. The upper limit thus defines the threshold above which a clinical reaction may be observed (e.g., discomfort, pain, swelling, stress fracture). The definition of the functional envelope remains a theoretical concept, with a large variation among individuals and over time. It remains difficult to determine the individual upper and lower thresholds.

Figure 95-1 Functional envelope according to Dye.

(From Dye SF: The knee as a biologic transmission with an envelope of function: a theory. Clin Orthop Relat Res [325]:10–18, 1996.)

Nevertheless, the profile of the functional envelope will be modified by medication, surgery, and rehabilitation. Each type of intervention will modify the functional envelope in a specific way; for example, total knee arthroplasty will change the aspect of the curve differently than an osteotomy.

These considerations must be taken into account:

1 The patient has the possibility to modify his or her activity (or body weight) to re-enter the functional envelope.

2 The aim of surgery is to enlarge this envelope. If a zone of the envelope will be reduced, it has to be clearly explained to the patient.

If the patient applies excessive force, above the threshold, the risk for failure is increased.

Functional Results of an Osteotomy

The survival rate is 70% at 10 years³³ and the infection rate is less than 0.5%.

Radiologic Workup

The radiologic workup is the same for all types of osteotomies and in our daily practice is no different from that for UHKs and total knee protheses. It includes the following:

Prior to the intervention, preoperative radiographic evaluation is essential. It includes a bipodal stance full leg film that allows measuring of the different angles and axes. The mechanical femoral axis is represented by a line connecting the center of the femoral head and middle of the tibial spine. The mechanical tibial axis connects the middle of the tibial spine and middle of the ankle joint. The mechanical femorotibial axis represents the overall deformity of the lower limb. This view will define the origin of the deformity (at the level of the femur or tibia) and will thus indicate the level at which to perform the osteotomy, importance of the overall deformity, and amount of correction that will have to be performed.

Stress x-rays in varus and valgus will illustrate articular laxity and reducibility of the deformity. Measurement of the constitutional varus is the epiphyseal axis as defined by Levigne⁴⁷—a line connecting the middle of the tibial joint line and the middle of the line connecting the tibial epiphesis. This axis forms a constant angle of 90 ± 2 degrees to the lateral tibial plateau (Fig. 95-2). The constitutional deformity of the tibia is defined as the angle between the epiphyseal and tibial mechanical axes (Fig. 95-3).

Figure 95-2 Epiphyseal axis, as defined by Levigne. This is a line connecting the middle of the tibial joint line and the middle of the line connecting the tibial epiphesis. This axis forms a constant angle of 90 ± 2 degrees to the lateral tibial plateau.

(Adapted from Levigne CH: Interêt de l’axe épiphysaire dans l’arthrose. In Neyret P, Dejour H [eds]: Journées Lyonnaises de chirurgie du genou, Lyon,1991, Hôpital de Lyon Sud, pp 127–141.)

Figure 95-3 Constitutional deformity of the tibia—defined as angle between epiphyseal axis and tibial mechanical axis.

(Adapted from Levigne CH: Interêt de l’axe épiphysaire dans l’arthrose. In Neyret P, Dejour H [eds]: Journées Lyonnaises de chirurgie du genou, Lyon,1991, Hôpital de Lyon Sud, pp 127–141.)

Sometimes, it is difficult to determine the middle of the tibial joint line and where to perform the measurement. Therefore, we prefer to determine the level of the original tibial plateau by the line tangent to the normal contralateral tibial plateau. Subsequently, the mechanical tibal axis is drawn. The angle between both axes is the angle α. The constitutional varus is defined by the complementary angle 90α (Fig. 95-4).

Figure 95-4 The level of the native tibial plateau is determined by the line tangent to the normal contralateral tibial plateau. The mechanical tibal axes are then drawn. The angle between both axes is the angle and the constitutional varus is defined by the complementary angle 90 −α.

Additional radiologic investigations also include a computed tomography (CT) scan to determine the presence of rotational problems. Certain patients with a frontal valgus or varus deformity can develop a unilateral arthritis at the side of the convexity of the malunion. This lateralization of the degenerative process can be explained by the rotational problem. An internal medial rotation will cause a lateral femorotibial arthrosis, whereas an external rotation of the femur will cause a medial femorotibial arthrosis.

Indications

The indication is often a compromise and represents a choice made by the patient and surgeon. For teaching purposes, we would like to note that it is not always possible to have ideal indications. Sometimes, one or more criteria will make the indications limited or disputable.

Activity Level

The preoperative level of activity and expected postoperative level of activity of the patient will influence the indications of osteotomy. We are more likely to treat even an older patient with a high level of activity, including sports, by an osteotomy.

Type of Arthritis

Lateral Gonarthrosis

This type of OA, with valgus deformity, is of mixed origin, both on the femur and tibia, and in our experience the clinical outcome is less reproducible. We attempt to achieve a normal correction between 0 and 2 degrees of varus.

Opening Wedge Distal Femoral Osteotomy

Because the origin of the valgus knee is situated in the distal femur, an osteotomy of the distal femur seems logical. Nevertheless, we have to understand that a correction by osteotomy is only obtained in the frontal plane, in extension (Fig. 95-5). The anatomy and alignment are not changed in flexion and thus a valgus knee will persist in flexion after a distal femoral osteotomy. Therefore, the indication for a distal femoral osteotomy is a valgus knee in extension (Fig. 95-6). We currently believe that the classification of the valgus knee according to the origin of the deformations is not yet well understood and that the deformities at a level of the diaphysis are still not yet included. A distal femoral osteotomy requires a rigid fixation and is associated with more blood loss and a high risk for arthrofibrosis.

Figure 95-5 A, Correction by femoral osteotomy is only obtained in the frontal plane, in extension. B, HTO for varisation (medial closing wedge high tibial osteotomy), on the contrary, will have an effect both in extension and flexion.

(Courtesy Dr. P. Chambat.)

Figure 95-6 Typical indication for a distal femoral osteotomy—valgus knee in extension and no valgus in flexion.

We have generally performed a distal femoral osteotomy in the younger patient with a valgus of distal femoral origin. The patient should be well motivated.

High Tibial Osteotomy for Varisation (Medial Closing Wedge High Tibial Osteotomy)

This type of osteotomy, on the contrary, will have an effect in extension and in flexion, and is the only one with an action in flexion. It is indicated and justified in those valgus knees of mixed origin. However, it is accompanied by a risk for an important obliquity in the joint line. This obliquity, if greater than 10 degrees, can lead to excessive stress on the patellofemoral joint, especially on the medial side. We propose a medial closing wedge high tibial osteotomy for the patient who is 60 years old (average age) with a high activity level, including sports, with a valgus knee of mixed origin or of tibial origin that is less than 8 degrees.

Clinical Criteria

The age of the patient has to be taken into account. In a young patient with limited or early medial OA, we prefer an opening wedge high tibial osteotomy. The patient’s weight can also influence the decision; morbid obesity has a negative influence because of loss of correction in the osteotomy on one side and because of difficulties during the non–weight-bearing period on the other side.

Arthritis secondary to ACL rupture can influence the choice of the technique. Because of the wear pattern located more posteriorly on the tibial plateau as a result of the ACL rupture, decreasing the tibial slope will limit the anterior tibial translation. Therefore, a closing wedge high tibial osteotomy seems to be more appropriate.

Radiologic Criteria

The origin of the deformation can be determined radiographically:

Radiologic Workup

The height of the opening wedge to obtain a valgus correction of 3 to 6 degrees is calculated as a function of the width of the tibia at the level of the osteotomy and the angular correction needed.

Patient Preparation

The patient is in a supine position. A tourniquet is generally used. The patient is draped using an extremity sheet and the image intensifier is installed. A slightly oblique, almost horizontal anterolateral skin incision is made. It starts 1 cm above the anterior tibial tuberosity and goes laterally 1 cm below the fibular head. The insertion of the tibialis anterior is released as a Z-plasty. Subsequently, the tibialis anterior muscle and long toe extensor muscle are released from the tibial metaphysis using a large periosteal elevator.

Osteotomy of the Neck of the Fibula

The neck of the fibula is identified and presented. A periosteal elevator is slid around the neck, always staying in contact with the bone. This protects the peroneal nerve. Four holes are now drilled in the neck using a 3.2-mm drill. With the use of the osteotome, the four holes are interconnected and the segment is removed using a large grasper. The fibular shaft should be mobile. Care is taken that the peroneal nerve is not entrapped in the osteotomy.

Closing Wedge Osteotomy of the Tibia

Specific instruments are available to perform the HTO and its fixation reproducibly. The osteotomy is done proximal to the tibial tubercle in an oblique direction. Imaging identifier control of the pin position is unnecessary if the following guidelines are followed:

We use the HTO Intrasoft device (Tornier Orthopedics, Montbonnot, France) for the fixation.. This blade plate–screw system has been specifically designed to minimize subcutaneous irritation. Different lengths of blade and screws are available to adapt to the different widths of the tibia.

A small guide pin is introduced at the level of the joint line and an alignment guide is subsequently introduced over this guide pin. The alignment guide will now automatically give the position and direction of a second guide pin parallel with the joint line and 1 cm distal to it.

We then introduce the blade reamer over the second guide pin. The length of the blade should be 1 cm shorter than the total width of the tibia. The box preparation guide is introduced over the guide pin and impacted. Four 6-mm diameter drill holes are made. The HTO blade is introduced and impacted into the box (Fig. 95-7).

Figure 95-7 Introduction and impaction of the blade.

Then we perform the distal cut of the closing wedge osteotomy. Many surgeons use a guide pin for the distal cut of the osteotomy but we do not believe that this is necessary. The posterior surface of the tibia is protected by a large periosteal elevator and the patellar tendon is retracted anteriorly. An oscillating saw is used to make the distal cut.

An angled cutting guide (6, 8, or 10 degrees) is introduced in the distal cut of the osteotomy and the proximal cut is now made using this angle. The cutting guide should be introduced and impacted on the medial cortex. An oscillating saw is used. The bone wedge is removed (Fig. 95-8).

Figure 95-8 Removal of the bone wedge.

The medial cortex is weakened with a 3.2-mm drill. A provisional unicortical screw is positioned distally from the osteotomy. This will be used as support for the reduction clamp. The wedge is closed with the reduction clamp (Fig. 95-9). Using a long metal bar positioned on the center of the femur head and in the middle of the ankle joint, the mechanical femorotibial axis is evaluated. The metal bar should pass just laterally to the lateral tibial spine (Fig. 95-10). The osteotomy is fixed with two bicortical long screws that are introduced through the blade into the distal tibia. The muscle insertions are now closed over a drain. The skin is closed with separate sutures.

Figure 95-9 A, Closing of the wedge with the reduction clamp. B, Using a long metal bar positioned from the center of the femur head to the middle of the ankle joint, the mechanical femorotibial axis is evaluated. The metal bar should pass just laterally to the lateral tibial spine.

Figure 95-10 Closing wedge high osteotomy of the tibia, with 5-year follow-up.

Other fixation devices and guiding jigs are available, such as the swan neck blade plate,^21,50 classic blade plates,^43,64 and staples.^{6,17,30,87,93} One study has shown the biomechanical superiority of plate fixation for proximal tibial osteotomy.²⁸ There is no advantage in using staples as a means of fixation because the plates and blade plates that are now available are more stable and do not carry additional risks of complications.

Patient Preparation and Skin Incision

The patient is placed in a supine position. A tourniquet is applied. An extremity sheet is used for the knee and a small square field is applied on the ipsilateral iliac crest. A small cushion is positioned underneath the buttocks to obtain a better exposure of the iliac crest. An 8-cm-long horizontal anteromedial skin incision is made, starting anteriorly just proximally to the tibial tubercle. The pes anserinus tendons are retracted. The superficial medial collateral ligament is incised at the level of the osteotomy (Fig. 95-11). The posterior surface of the tibia is exposed using a large periostal elevator.

Figure 95-11 Incision of the superficial medial collateral ligament at the level of the osteotomy.

During the osteotomy, this periosteal elevator is left in place. Anteriorly, the patellar tendon is retracted using a Farabeuf retractor.

Procedure

The osteotomy is performed proximally to the tibial tubercle and through the superficial medial collateral ligament, which has previously been incised. The plane of the osteotomy is horizontal, slightly different from the closing wedge medial HTO, which is more oblique. First, two Kirschner 20/10 guide pins are introduced medially. Laterally, these guide pins should be just superior to the head of the fibula.

An imaging identifier control is now performed to evaluate the correct position of the guide pins. The direction can be adjusted, if necessary (Fig. 95-12). Using an oscillating saw, the tibial cut is made underneath these guide pins, but always staying in contact with them (Fig. 95-13). First, the center of the tibia is cut, followed by the anterior and posterior cortex. The cuts are completed using an osteotome, especially on the anterior cortex, where the patellar tendon is in danger.

Figure 95-12 Control of the correct position of the guide pins with imaging identifier. The pins should be introduced from a medial direction and be just superior to the head of the fibula laterally.

Figure 95-13 The tibial cut is performed underneath two guide pins introduced medially.

It is necessary to have an intact lateral hinge for this type of osteotomy. This hinge can be damaged by a number of drill holes.

Subsequently, a Lambotte osteotome (thickness, 2 mm, corresponding with approximately 2 degrees of angular correction) is introduced into the osteotomy. A second osteotome is now introduced below the first. To open up the osteotomy gently, several more osteotomes are introduced between the first two (Fig. 95-14).

Figure 95-14 Progressive and controlled opening up of the osteotomy with several osteotomes introduced between the first two.

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