Osteotomy for the Arthritic Knee: A European Perspective

Chapter 95 Osteotomy for the Arthritic Knee


A European Perspective



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Osteotomy: General Principles and Indications


Before the introduction of unicompartmental* and total knee arthroplasty into clinical medicine,22,26,73 an osteotomy of the knee was the treatment of choice for gonarthrosis.16,20,40,57 It has a long past, dating back to the 19th century.90 Today, however, an osteotomy is considered technically difficult for many surgeons and demanding for the patient. Nevertheless, osteotomies remain an important treatment option for arthritis of the knee in our daily practice because they authorize a return to a high level of activities, including sports, and can delay the need for a total knee prosthesis in young and active patients.


The indications for osteotomy should be defined. Many factors have to be taken into account, such as the type of arthritis, clinical and radiologic criteria, and level of patient expectations.



Why an Osteotomy?


The surgical management of gonarthrosis includes three types of interventions—osteotomies, unicompartmental arthroplasty (UKA), and total knee arthroplasty (TKA). Considering the improvement of the outcome of total22,26,73 and unicompartmental12,44,65 knee arthroplasties reported in recent years, the legitimate question arises about the necessity of osteotomies. The final choice of interventions will largely depend on the history of the patient, functional complaints, motivations, clinical examination, and radiologic findings.




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.



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:




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




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).




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).



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.





Factors Influencing Choice of Osteotomy



Type of Arthritis



Medial Gonarthritis


Some factors support an osteotomy:







Opening Wedge Osteotomy

There are many advantages in comparison with a closing wedge osteotomy: a more accurate correction; no peroneal nerve injury (palsy); and can be combined with an ACL reconstruction through the same incision.72 The disadvantages are that a graft is needed (e.g., bone graft, ceramic), the consolidation may be longer (8 to 10 weeks), and the tensioning of the extensor system (and, to a lesser degree, the medial collateral ligament and medial tendinous structures). We prefer an opening wedge high tibial osteotomy for the younger patient with preosteoarthritis or limited osteoarthritis.




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.




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


In case of medial OA in association with a genu varum morphotype, a high tibial osteotomy remains an important surgical option. The long-term clinical outcome at 10 years continues to be favorable in more than 70% of patients if the frontal angular malalignment has been corrected to 3 to 6 degrees of valgus.


The main reasons for failure are the following:





Despite the progression in cartilage degeneration overtime, this type of intervention remains indicated, especially for middle-aged individuals.


Two surgical techniques are available. First is the opening wedge medial HTO, which should be associated with the use of a bone graft. Second is the lateral closing wedge high tibial osteotomy associated with a fibular neck osteotomy. The clinical outcome is more predictable in nonobese patients. Therefore, we generally provide information preoperatively on hygiene, smoking cessation, and caloric intake.


If we have a young, sports-minded patient, an osteotomy still remains the option of choice before an arthroplasty.




Lateral Closing Wedge High Tibial 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).



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).



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.




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.



Medial Opening Wedge High Tibial Osteotomy




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.




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).


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Aug 27, 2016 | Posted by in ORTHOPEDIC | Comments Off on Osteotomy for the Arthritic Knee: A European Perspective

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