Osteotomies Around The Knee Book

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Roselee Kruppa

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Aug 3, 2024, 1:07:46 PM8/3/24

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This review article describes the main osteotomies performed around the knee and their optimization, with particular attention to indications and surgical technique in light of the most recent literature and author experience.

The history of osteotomies starts in the 16th century, but the real development of these techniques has improved between the 19th and 21st centuries, to become the gold standard treatment for the unicompartmental osteoarthritis of the knee. The growth of arthroplasty surgery and the subsequent technologic development of new, reliable and better performing prostheses, mostly implanted in elderly patients with low function, led to a progressive loss of interest for osteotomies. However, over the years, studies (1) underlined unsatisfactory clinical results for knee arthroplasties in more active and sportive patients. In this setting, osteotomies made their comeback in the therapeutic arsenal of unicompartmental osteoarthritis. Indications were better tailored to patients (Fig. 1 and Table 1), and techniques were furthermore developed and making the degree of correction more reliable. Advanced development of fixation plates and modern postoperative rehabilitation protocols have made osteotomies more attractive.

Proximal tibial osteotomy (PTO) is a cornerstone procedure in the treatment of medial compartment osteoarthritis in a varus knee, in which weight-bearing forces are mostly transmitted across the medial tibiofemoral compartment, leading to eventual and progressive damage to the articular cartilage and the subchondral bone. The aim of this procedure is to shift the mechanic axis of the knee, leading to a decreased area of contact and progressive unloading of the affected compartment. Finally, the objectives are to reduce pain for the patients, increase their function, delay the progression of medial arthrosis and the need for knee replacement surgery.

The ideal candidate for PTO is a young patient (90 of flexion on the affected knee. Relative contraindications are age >65 years, impaired range of motion with 30) and patients with bicompartmental arthritis or with previous lateral meniscectomy (2). Smoking plays a negative role especially as it may interfere with bone healing in open-wedge PTO and may cause nonunion.

Instability used to be a contraindication in PTO, but nowadays sagittal and coronal alignment modification through this surgical technique may represent a useful solution in a patient with anterior cruciate ligament (ACL) rupture and posterolateral corner injuries (PLC). Varus deformity results in the tensile force on ACL to increase, and a varus alignment >5 is recognized as a risk factor for failure of ACL reconstruction. Nowadays, PTO might be performed, if degenerative changes occur, in patients with varus knee plus ACL rupture in the absence of dynamic instability on weight-bearing lateral radiographs. ACL reconstruction may be combined with PTO or performed as a second surgical stage, usually in patients with painful instability combined with medial degenerative changes in a varus knee (3).

Chronic PLC laxity leads to a decreased ability for withstanding a loading stress applied to the knee and varus alignment worsens this situation. Therefore, according to Arthur et al. (4), correction of the varus alignment through PTO alone can result in better knee stability and good clinical outcomes, while only 38% of their cohort needed a second stage procedure consisting of ligament reconstruction.

Many PTO techniques have been developed and used in history, but today, opening- and closing-wedge osteotomy are the most commonly used (see Table 2). In the lateral closing-wedge technique, correction is achieved by removing a bone wedge from the lateral tibia, retaining the hinge and closing the gap. It has been widely used in the past for its high rate of consolidation, but progressively lost part of its popularity due to some disadvantages, such as shortening of the leg, the need for fibular osteotomy, the interruption of proximal tibiofibular joint and the risk of peroneal nerve injury. On the other hand, in the medial open-wedge technique, a single line osteotomy is performed respecting a lateral hinge and a progressive opening is realized until the planned wedge and degree of correction are reached. The site is then fixed with a plate and might be filled with a bone graft. This technique preserves the bone stock, but it affects the position of the patella and it carries the disadvantage of a possible nonunion. Besides, the open-wedge technique might be performed in multiple planes: biplanar osteotomies are performed when an additional cut is made at the anterior third of the tibia behind the anterior tibial tubercle (ATT) at about 110 of the horizontal osteotomy. With this method, the tibia is prevented from rotating around the vertical axis and it creates an anterior buttress against sagittal movements. Moreover, this results in a higher surface of bone contact, enhancing the possibility of a good and rapid consolidation.

In the planning of a PTO, patellar height and eventual leg length discrepancy should be critically determined, since the biplanar open-wedge technique results in a distalization of the patella and an increase in the leg length. We know that the patella height will decrease approximately 2 mm per 10 of valgus correction (2). One solution would be to orient the oblique osteotomy cut distally to the ATT, and fix it with one or two bicortical screws. This may be indicated in patients requiring a correction of more than 10 and/or in patients with a preexisting patella infera. Regarding leg length discrepancy, a close-wedge osteotomy may be better indicated in patients with a discrepancy of more than 1.5 cm in favor of the operated leg.

There is still a large opportunity for improvement in osteotomies including further development in navigation systems, especially to navigate the tibial slope, control the joint line obliquity and the precision of the correction in double level osteotomies. Preoperative 3D-CT scan planning resulting in individualized cutting blocks and customized plates may improve the reliability and the precision of the osteotomy, as well as facilitate its realization. Those techniques are still in development and their performances are still under investigation.

Distal femur osteotomy (DFO) is a well-known surgical procedure used to correct the valgus deformity, that might be also post-traumatic or due to growth disorders, in young active patients with lateral compartment arthrosis or cartilage damage. In this case, the goals are to unload the lateral compartment in order to decrease pain and osteoarthritis progression. Valgus deformity is less frequent than varus, so not so many papers are published on DFO postoperative outcomes. However, surgeons must keep in mind that valgus malalignment is not only represented by a femoral-based deformity. In fact, recent studies highlighted that the malalignment may be due to a tibial-based or a combined femoral and tibial deformity (10).

DFO can be indicated in patients affected by chondral lesions of the lateral compartment in a valgus knee, in order to achieve correction of the malalignment and protection of the chondral repair. Cartilage treatment can be combined at the same time as the correction of the deformity, whereas deformities due to growth disorders or post-traumatic must be addressed, if possible, before the onset of the arthrosis. DFO might also be beneficial in young, sportive patients, even with initial stage of osteoarthrosis, who need a concomitant lateral meniscus allograft transplantation, in order to offload the lateral compartment and the freshly implanted allograft.

In case of ligamentous instability, DFO can be performed as a standalone procedure or combined with a concomitant or staged ligament reconstruction. For example, some studies have analyzed the outcomes after lateral open-wedge DFO alone performed on valgus knee with MCL deficiency, showing a decrease of the medial opening at 30 of flexion. This could be considered in low-demand patients (12).

DFO can be performed as a lateral open-wedge technique or as a medial close-wedge one (Fig. 2). In the first one, osteotomy is performed with an inclination of 20 from two to three fingers proximal to lateral epicondyle aiming at a point few millimeters proximal to the medial epicondyle, in order to remove a bony wedge of predefined dimension and gently opening the site in varus until the desired degree of correction is reached. The site is then fixed with plates and might be filled with bone graft. The medial hinge should be preserved by advancing the oscillating saw no more than 1 cm away from the medial cortex, as it is more fragile and prone to fracture, resulting in collapsing of the osteotomy site and great difficulty in controlling the rotational stability (13). This procedure is technically more demanding, but allows an accurate correction and the restoration of the femoral height, especially in those patients requiring mild to large correction. On the other hand, the disadvantages of this procedure are represented by the danger of hinge fracture and the incidence of delayed union or nonunion of the osteotomy site. A study analyzed the biomechanics result of the femoral osteotomies, highlighting how the lateral open-wedge technique resulted in inferior stability and in lower stiffness compared to the close-wedge one. Therefore, a bone graft or substitute should be mandatory in order to enhance the biological healing. In the close-wedge technique, parallel pins are then driven in the cortex from the medial supracondylar area to the lateral condyle and the proximal part of the osteotomy is performed through the antero-posterior cortex, preserving the lateral one. The bone wedge is removed and the osteotomy site is closed and fixed, compressing the medial cortex. The conventional single plan osteotomy has been replaced by the biplanar technique, in which the osteotomies are performed in the posterior three-quarters of the femur and completed with an ascending cut performed on the anterior surface of the femur. This technique allows for a more distal positioning of the lateral hinge point, a wider contact of surface and more accurate control of the rotational stability. Finally, it enhances biological bone healing. Furthermore, studies reported no loss of correction in the follow-up examination and low incidence of nonunion. However, there is still an active debate about the indication to open- versus close-wedge surgical techniques. A recent systematic review (14) showed similar outcomes for the two procedures, with no difference in radiographic correction, bony healing or patient-reported outcomes.