Which osteotomy for a valgus knee? (2024)

Abstract

A valgus knee is a disabling condition that can affect patients of all ages. Antivalgus osteotomy of the knee is the treatment of choice to correct the valgus, to eliminate pain in the young or middle age patient, and to avoid or delay a total knee replacement. A distal femoral lateral opening wedge procedure appears to be one of the choices for medium or large corrections and is particularly easy and precise if compared to the medial femoral closing wedge osteotomy. However, if the deformity is minimal, a tibial medial closing wedge osteotomy can be done with a faster healing and a short recovery time.

Introduction

The rationale behind the osteotomy is to correct the angular deformity at the knee and, therefore, decrease the excessive weight bearing load across the affected compartment which is the most involved by the degenerative process. Since alternative treatments in the 1970s for severe degenerative and inflammatory diseases of the knee were limited, femoral osteotomy was used early on for osteoarthrosis (OA), rheumatoid arthritis and secondary arthrosis, regardless of the aetiopathogenesis and the magnitude of the angular deformity.

The young patient with knee OA or with an initial condral pathology presents a challenging treatment dilemma to the orthopaedic surgeon. A valgus painful knee is a disabling condition that can affect patients of all ages. Anti-valgus osteotomies are the treatment of choice to correct the valgus deformity and eliminate pain and other functional problems. In particular, patients with an early arthritis of the lateral femoro-tibial compartment or damage of the cartilage of the lateral femoral condyle are candidates for anti-valgus osteotomies. Both the lateral femoral condyle and the lateral tibial plateau have convex surfaces, the congruence of which is maintained thanks to the integrity of the lateral meniscus. The absence of the meniscus can lead to a progressive deterioration of the opposing cartilage surface, due to the increased concentration of stress. Middle-aged patients with previous involvement in sports activities can develop lateral femoro-tibial arthritis early, which may lead to a lateral meniscectomy in early age. Damage to the cartilage of the lateral femoral condyle associated with an anterior cruciate (ACL) and or posterior cruciate (PCL) acute tear or chronic laxity can also lead to lateral meniscectomy. A congenital valgus deformity often associated with excessive weight can also cause early lateral arthritis due to the rapid degeneration of the meniscus and then of the cartilage. A lateral meniscus cyst or a lateral discoid meniscus represent a relatively frequent indication for a “subtotal” meniscectomy even in young athletes. All of the above may be considered candidates for anti-valgus osteotomy.

Indications and contraindications

Nowadays we believe that the patients selected for a distal femoral osteotomy should have mostly unicompartimental OA with axial malalignment. However, fracture and other trauma, congenital and acquired deformities, and idiopatic osteonecrosis may also be in particular cases indications for the osteotomy. There is no definite age below which one should do an osteotomy and above which one should do an arthroplasty. The age of 60 is the most often cited, but activity level, lifestyle and general health must be considered. As long-term studies of arthroplasty would demonstrate, age considerations may change; but it still remains that the age group of osteotomy patients is generally younger than that for knee arthroplasty. Furthermore, the actual trend seems to be oriented towards an early treatment of the unicompartimental OA in relatively young patients since the better results are to be expected when the articular changes are in the initial stage of the degenerative process. Osteotomy is best done for primarily unicompartimental OA in knees with generally well maintained range of motion (ROM). Osteotomy should probably not be done in patients with rheumatoid arthritis, patients with very unstable knees, nor in knees with greater than 20° of varus deformity, because, according to Insall, these knees are complicated by an associated severe ligamentous laxity and subluxation. The latter is a relative contraindication; in fact, even if the correction of the mechanical axis in such a great deformity can result in a relaxed collateral ligamentous complex, often the knee develops a new functional stability and many authors, including ourselves, do not routinely perform retightening of the ligamentous structures.

A patient who has a valgus deformity and anterior cruciate ligament (ACL) insufficiency may be treated with an ACL reconstruction in addition to the distal femoral osteotomy. A technically demanding procedure, the osteotomy associated with the ligament reconstruction addresses the underlying disorder and corrects the problems. Because it is not a routine procedure, it will not be discussed here. However, the symptoms of pain and instability must be separated as clearly as possible because when the pain prevails, especially in sedentary patients, correction of alignment, with consequent relief of lateral compartment pain can be a satisfactory treatment.

The case of the overweight patient is a controversial topic generating a conflict of opinions. Obesity has a negative effect on the outcome of surgery in many orthopaedic operations. Most would agree that excess body weight could make a patient a better candidate for osteotomy than for arthroplasty, but it is also true that obesity will represent a negative factor in view of the possible general postoperative complications. When a patient is overweight, the weight should be brought to near normal before surgery since worse long-term results for osteotomy related to obesity have been demonstrated. Contraindication to the osteotomy is severe bone loss (more than a few millimeters) of the lateral tibia or femur. When lateral compartment bony support is insufficient, congruent weight-bearing on both tibial plateaus following the osteotomy is not possible. In this situation, tibiofemoral contact will teeter on the relatively prominent intercondylar tibial spines.

The presence of severe valgus deformity may be associated with subluxation of the tibia. Subluxation greater than 1cm is an absolute contraindication to osteotomy and some authors suggest that osteotomy should not be performed if any translation or subluxation is present.

Antivalgus osteotomy is designed to relieve pain caused by an initial arthrosis of the lateral knee compartment. Slight degenerative changes of the patellofemoral joint are not a contraindication to osteotomy, since following a distal femoral opening wedge osteotomy, the Q angle is reduced and the anterior tibial tubercle is medialised, unloading the patello femoral compartment.

Radiographic assessment and preoperative planning

The standard evaluation begins with an assessment of the alignment of the lower limbs with four short films: bilateral weight bearing antero-posterior views in full extension and bilateral weight bearing postero-anterior views at 45°. To complete the evaluation of the knee, we look at the different radiographic views, including the standard lateral and the axial views of the patellofemoral joint. The Rosenberg view [1], a comparative posteroanterior weight-bearing radiograph at 45 degrees of knee flexion, facilitates the diagnosis in case the standard anteroposterior (AP) view is not sensitive enough (Fig.1). It has a strong predictive value, especially when the deformity is associated with a cruciate insufficiency, and therefore the chondral wear prevails in the posterior part of the tibial plateaus. Most authors do not recommend computed tomography (CT) scans or magnetic resonance imaging (MRI) in studying a candidate for knee osteotomy; but we think that the stress reaction of the subchondral bone, detectable by MRI, could be the only sign of a degenerative process at its earlier stage. If an anti-valgus osteotomy is indicated, one should obtain a bilateral full length standing alignment film with the femoral head and the ankle included in the X-ray. Several measurements taken from these films will assist the preoperative planning. Measurement of the mechanical axis, a straight line drawn from the centre of the femoral head to the centre of the talus is most important, as it indicates where the weight passes through the knee joint. Lateral radiographs are assessed for sagittal plane deformity, including measurement of tibial slope. The osteotomy is planned according to the method described by Dugdale et al. [2]. The weight bearing line is placed at a selected position 48–50% across the width of the tibial plateau from medial to lateral. The correction angle is formed by the angle between the line from the centre of the femoral head to 50% of the width of the tibia and the line from the centre of the talus to the 50% coordinate (Fig.2). By measuring the width of the femur at the level of the proposed osteotomy, the surgeon can convert the angular correction into the wedge size. Extensive clinical experience has shown that over correction in varus is absolutely contraindicated for an optimal long-term result from osteotomy.

Surgical options

To perform an anti-valgus osteotomy, the surgeon can choose among three main surgical options: distal femoral medial closing wedge osteotomy, distal femoral lateral opening wedge osteotomy and proximal tibial medial closing wedge osteotomy.

Surgical technique

Postoperative management

After surgery the knee is immobilised with a range-of-motion brace in full extension or at slight flexion of about 10° that allows a full range of motion when unlocked. Passive flexion and extension in a continuous passive motion device are started the day after surgery. The drains are removed 48 hours later. Patients are allowed to walk with no weight bearing on the limb from the second postoperative day. They are discharged from the hospital in three to fourdays when postoperative knee pain and effusion are minimal, and range of motion (ROM), flexibility and strengthening exercises commence. The exercise program must also integrate the trunk, hip and ankle muscles to provide dynamic knee stabilisation while addressing isolated quadriceps femoris deficiencies. Physical therapy intervention with the knee osteotomy patient requires continual attention to the balance between protection and function. Although progressive weight bearing and ROM exercises are vital to recovery, excessive early joint loading and terminal knee flexion–extension with external loads can compromise the integrity of the surgical realignment. Patients are usually able to completely flex the knee within the first fourweeks following surgery. After sixweeks partial weight bearing is allowed. Full weight bearing is normally possible after eight or nineweeks provided there is radiographic evidence that the bone has healed sufficiently. Restoring proprioceptive-kinesthetic normality at the involved lower limb must also be emphasised. The absence of apparent discomfort or movement-avoidance patterns assures the therapist that neuromuscular control for dynamic knee stabilisation is improving. In older patients, particularly those that have not recently participated in a physical exercise regimen, rehab may need to be delayed. In such cases rehabilitation should concentrate on active ROM to facilitate articular cartilage nourishment and preservation.

Tibial medial closing wedge osteotomy

When a small correction is required, tibial medial closing wedge osteotomy may be a suitable surgical choice (Fig.11a). In our experience, supported by Coventry [9], Chambat et al. [10], and Marti and Verhagen [11], a joint surface tilt of 10° in the coronal plane is well tolerated. If the correction is greater than 10° the tibia gradually subluxates laterally [12], and on an anteroposterior radiograph, the femur appears to fall off the medial tibial plateau. A medial proximal tibial approach is used (the same as in opening wedge osteotomy). No graft is required and healing generally occurs in fourweeks from surgery.

After arthroscopy, an antero-medial longitudinal skin incision is performed; the pes anserinus is partially detached. The superficial layer of the medial collateral ligament is divided and the medial tibial metaphysis is exposed. The distal insertion of the patellar tendon is exposed and the osteotomy site confirmed with fluoroscopy using a Steinmann pin. The pin is driven from medial to lateral and from distal to proximal above the tibial tuberosity, pointing towards the fibular head. The osteotomy is begun with the oscillating saw then completed by the appropriate osteotome running underneath the guide wire to prevent entering the epiphisis or the joint space. It is necessary to leave at least 5mm of intact lateral tibial cortex (“hinge”) to ensure good stability of the osteotomy. Resection must be minimal and can be performed under fluoroscopy and should be commensurate with the preoperative planning. As in the distal femoral open wedge osteotomy, the final correction has to bring the mechanical axis to the mid point of the tibial plateau. It is important that resection be minimal and, by forcing the knee into varus, fracture of the lateral hinge permits medial bone impaction and good bone contact. Final correction can be checked intraoperatively with the guide rod. The osteotomy is fixed with one or two staples (Fig.11b) or with a four-hole plate. Postoperatively, the lower limb is immobilised in a functional brace with unlimited range of motion and full weight bearing at 30days. One can expect complete healing of the osteotomy by six to seven weeks from surgery.

Complications

The risk of intrarticular fracture is always present. This is more often due to a mistake in positioning the guide pin too close to the joint, leaving little metaphysical bone stock between the osteotomy and the articular surface. It also may result from failure to completely divide the posterior or more often anterior cortex. This may cause an articular fracture to occur when the correction is attempted. The osteotomy jack reduces this risk, but does not eradicate it completely. Another possible intraoperative complication is subluxation of the osteotomy. It can happen when the surgeon does not leave a sufficient hinge of intact bone. Preventing this technical problem starts with the proper choice of the site of the osteotomy cut. The cut should be sufficiently distal in the femur to avoid the maximum step-off of the bone profile and obtain a more stable fixation. An intact bone hinge is essential for stability and, when correctly performed, protects the osteotomy from possible dislocation. If the undesired subluxation has occurred, a possible method of correction is a staple fixation through a controlateral incision.

Failure of the hardware, especially the plates, is very rare. Vascular injuries are very rare provided the surgeon protects the vessels through correct use of a posterior Homan retractor and the knee remains flexed during surgery. Thrombophlebitis and infections are generic complications common to all other surgical procedures performed on the lower limb.

Results

The results of supracondylar osteotomy reported in the literature are generally good. Healy et al. [13] reported a series of 23 distal femoral osteotomies with a follow-up of fouryears. The Hospital for Special Surgery (HSS) Knee Score improved from an average of 65 points to 86 points postoperatively. McDermott et al. [14] reported on 24 patients for whom the greatest improvements were found in the “pain” category, with an average increase of 16.5 points. Miniaci et al. [15] reported 86% good or excellent results in a series of 40 supracondylar femoral closing wedge varus osteotomies, with a mean follow-up of 5.5years. Finkelstein et al. [16], in a study of 21 knees, demonstrated that the probability of survival at tenyears was 64%. Marti et al. [3], analysing 15 closed wedge varus femoral osteotomies, obtained 75% good results without any complication.

The author's experience includes a series of 21 patients with an average age of 54years (seven males and 14 females) operated upon between 1992 and 2002 with a follow-up of four to 14years (Fig. ​(Fig.12).12). Every patient improved according to both the International Knee Committe Documentation Committee (IKDC) rating scale and the HSS system.

In a series of 47 patients treated by a medial tibial closing wedge osteotomy and followed up for a minimum tenyears, Chambat et al. [10] found that 72% of patients had “good” and “very good” results, with an improvement in pain in 91%. In our six cases operated on between 1996 and 2002 there was excellent improvement of pain and functional capabilities with the HSS score improving from an average of 60 points to 87 points.

Conclusions

In valgus painful knees with degeneration of the lateral compartment in young or middle-aged patients, antivalgus osteotomies represent an effective surgical treatment. Unicompartimental prosthesis arthroplasty is indicated in older patients and particularly in those cases with osteonecrosis or severe lateral arthrosis. Patients with a depressed lateral compartment and extreme valgus deformity are more suitably treated with total knee replacement (TKR). The literature [16, 17] suggests that supracondylar osteotomy does not preclude TKR. A varus distal femoral osteotomy can make a future TKR technically easier [18]. Opening wedge lateral femoral anti-valgus osteotomy represents a precise and easy technique that allows accurate correction of the alignment, moving the weight-bearing axis from the lateral tibial plateau towards the centre of the knee joint. Moreover, its peculiar method of fixation by special plates with spacers helps prevent secondary loss of correction and shortening of the limb. The medial tibial closing wedge osteotomy is a valid alternative for minor corrections (10° or less). The procedure is easy, safe and does not compromise range of motion.

References