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Role of Osteotomy in Cartilage Resurfacing Procedures
Role of Osteotomy in Cartilage Resurfacing Procedures Robert A. Gallo, MD, Henry A. Boateng, MD, and Scott A. Lynch, MD Knee realignment osteotomies have become increasingly important as an adjunct to unload the affected compartment and theoretically protect cartilage repair. Owing to preservation of bone stock, medial opening-wedge high tibial osteotomy has become a popular treatment of varus malalignment, while lateral distal opening-wedge osteotomy is increasingly being used as a surgical treatment for correcting valgus malalignment. This study describes the preoperative assessment, technical description, postoperative rehabilitation, and potential pitfalls of each of these 2 osteotomies. Based on the results from a limited number of studies, expected outcomes following combined realignment osteotomy and cartilage restoration procedures have been reviewed. Oper Tech Orthop 24:253-263 C 2014 Elsevier Inc. All rights reserved.
Historical Perspective
O
steotomy has been used for more than a century to correct acquired and posttraumatic deformities around the knee.1 However, it was not until 1960 that the concept of osteotomy was applied to the treatment of knee osteoarthritis.2 Interestingly, in that sentinel study, Jackson encouraged a distal femoral osteotomy for the treatment of genu valgum and a proximal tibial osteotomy for genu varum. Over the next 2 decades, closed high tibial osteotomies, as popularized by Coventry3 and Insall et al,4 became a mainstay of treatment for both varus and valgus gonarthrosis. The interest in osteotomy waned during the 1980s and 1990s secondary to (1) design modifications and resultant improved outcomes following total and unicompartment knee arthroplasty, and (2) emergence of long-term follow-up studies after osteotomy. During this time period, multiple reports surfaced documenting a dramatic decline in outcome despite promising results within the first 5 years. Unsatisfactory outcomes, including conversion to total knee arthroplasty, Department of Orthopaedics, Bone and Joint Institute, Milton S. Hershey Medical Center, Pennsylvania State University College of Medicine, Hershey, PA. Neither the author nor an affiliated institute has received (or agreed to receive) from a commercial entity something of value (exceeding the equivalent of US$500) related in any way to this manuscript. Address reprint requests to Robert A. Gallo, MD, Department of Orthopaedics, Bone and Joint Institute, Milton S. Hershey Medical Center, Pennsylvania State University College of Medicine, 30 Hope Dr, Hershey, PA. E-mail: [email protected]
http://dx.doi.org/10.1053/j.oto.2014.05.005 1048-6666/& 2014 Elsevier Inc. All rights reserved.
occurred in 37%-63% of patients who were followed up beyond 10 years after osteotomy.5-8 The realization that osteotomy is often a temporizing procedure before a total knee arthroplasty also prompted a paradigm shift away from closing-wedge osteotomies and toward openingwedge osteotomies, which can maintain bone stock. Although opening-wedge high tibial osteotomy has become an increasingly popular treatment for varus malalignment, distal openingwedge osteotomy is a more common surgical treatment for correcting valgus malalignment because most of the deformity is usually within the distal femur and a lateral opening-wedge high tibial osteotomy is limited by the fibula. With the advent of cartilage restoration procedures, improvements in fixation hardware, and viable bone graft substitutes, there has been renewed popularity in knee osteotomies. Knee osteotomies have become a necessary tool in the armamentarium for surgeons performing cartilage restoration procedures or treating young, active individuals with arthritic change and malalignment who wish to maintain a sporting lifestyle.
Indications and Contraindications Realignment osteotomies should be considered to unload symptomatic articular cartilage maladies, femoral or tibial, associated with malalignment. Historically, the primary indication for realignment procedures has been isolated unicompartment osteoarthritis in a malaligned knee. Young, high-demand individuals with symptomatic unicompartmental grade III 253
R.A. Gallo et al.
254 osteoarthritis and malalignment are the ideal candidates for an unloading osteotomy. However, the degree of osteoarthritis and age are just 2 factors to consider when deciding to proceed with realignment osteotomy. Desired activity levels, expected outcomes, and other potential benefits and risks following both osteotomy and knee arthroplasty should be weighed and discussed with each patient to determine if realignment osteotomy is the preferred procedure to help each patient optimize his or her function. A realignment osteotomy should be considered in each patient undergoing a cartilage resurfacing procedure and having a weight-bearing axis that passes through or more peripherally within the compartment than the articular cartilage lesion (Fig. 1). We are more aggressive about performing an osteotomy to unload the affected compartment if there is an asymmetric malalignment, such that the affected compartment has a higher degree of deformity. Failure to address the malalignment theoretically subjects the cartilage repair to mechanical overload and premature failure. For a realignment osteotomy to produce a successful outcome, the articular cartilage and overall milieu of the compartment that the weight-bearing axis is shifted toward must be adequate to accept the increased load. Therefore, the
degeneration of the articular cartilage in the opposite compartment is a contraindication to realignment osteotomy. Similarly, owing to the potential of continued pain in other regions of the knee or continued poor function, those with patellofemoral arthritis, nonconcordant pain, ongoing infection, range of motion less than 901, and inflammatory arthritis are not usually considered for osteotomies that realign the mechanical axis.9 Although these are not absolute contraindications to realignment osteotomy, body mass index greater than 35 kg/m2 and tobacco smoking pose increased risk to loss of angular correction and nonunion of the graft, respectively10,11; therefore, osteotomy is not recommended until these factors are corrected. Finally, realignment osteotomies can produce cosmetic deformities, especially in cases where overcorrection is desired. Patients who are unwilling to accept the anticipated appearance are not appropriate for a realignment osteotomy.
Preoperative Planning The assessment of alignment begins with a full-length standing anteroposterior radiograph. An adequate full-length radiograph should (1) be obtained with double-leg stance, (2) include
Figure 1 Bilateral standing full-length radiographs of the extremity are obtained in patients with focal full-thickness chondral defects (A) who are contemplating undergoing an articular cartilage restoration procedure. Unloading osteotomy should be considered when the weight-bearing axis passes through the defect (B), and especially, when the affected compartment has more pronounced malalignment.
Osteotomy in cartilage resurfacing procedures the entire femoral head and ankle mortise, and (3) be taken with the knee slightly flexed (roughly 51) to avoid abnormal varus recurvatum.12 The weight-bearing axis is drawn from the center of the femoral head to the center of the ankle mortise, and its intersection on the tibia provides a rough estimate of the amount of correction required. We prefer medial opening-wedge high tibial osteotomy to correct genu varum and lateral openingwedge distal femoral osteotomy for genu valgum. However, if excessive varus correction is required, a medial closing-wedge distal femoral osteotomy should be considered to avoid overstretching the peroneal nerve. The rule of thumb used to preoperatively predict the extent of the osteotomy is that, for each degree of desired correction, 1 mm of lengthening (opening-wedge) or resection (closingwedge) must be performed on the “near” cortex to achieve the appropriate correction.13 This estimation proves accurate only when width of the tibial flare measures 56 mm, which is far more narrow than normal.14 Alternately, Dugdale et al15 described a method to calculate the wedge necessary to achieve the desired correction. In this technique, 2 lines are drawn: one from the center of the femoral head to the desired location where the weight-bearing axis crosses the tibial joint line and the other line drawn from center of the ankle mortise to this same point on the tibia. The acute angle formed by the intersection of these 2 lines is the correction angle required. Wedge height can be calculated by using the angle of correction to recreate the osteotomy wedge on radiographs.13
Technique Opening-Wedge Lateral Distal Femoral Osteotomy for Valgus Malalignment Patients are placed supine on a radiolucent table with the pelvis and leg length leveled. A C-arm image intensifier is positioned on the opposite side and perpendicular to the long axis of the affected extremity. The entire lower extremity from pelvis to ankle should be unobstructed to permit fluoroscopic imaging during the procedure. Regional anesthesia is generally avoided to accommodate neurovascular monitoring postoperatively. A tourniquet is applied proximally in the thigh and, owing to the vascularity of the vastus lateralis, is inflated to 300 mm Hg throughout the case. A lateral skin incision is marked from the lateral joint line and extended proximally 10 cm along the palpable anterior border of the vastus lateralis. The skin and subcutaneous tissue are sharply incised to the level of the vastus lateralis. The interval between the rectus femoris and vastus lateralis is exploited. We choose the interval anterior to the vastus lateralis to limit the exposure and potential injury to the perforating vessels. A Hohmann retractor placed extracapsularly on the anterior tibia is used to retract the rectus femoris anteriorly. If possible, the capsule should not be violated. A second Hohmann retractor is inserted subperiosteally around the posterolateral femur. Slight knee flexion can relax the posterior musculature and facilitate retractor placement. Precise placement of the posterior retractor is crucial to protect posterior neurovascular structures.
255 Once the distal femur, including the lateral epicondyle, is exposed, a 2.0-mm guidewire is passed through the distal femoral metaphysis proximal to the proposed osteotomy site and perpendicular to the long axis of the femur. A second guidewire is inserted across the distal femur and acts as a frame of reference for the osteotomy. Under anteroposterior fluoroscopic imaging, the guidewire is passed at the proximal margin of the lateral epicondyle and parallel to the joint line. An osteotomy guidewire is inserted into the distal femoral metaphysis 2 fingerbreadths above the lateral epicondyle. The guidewire is advanced distally toward the superior aspect of the medial epicondyle. Once satisfactory position of the initial osteotomy guidewire is attained, and if the width of the distal femur can accommodate 2 wires, a second osteotomy guidewire may be passed parallel to the osteotomy guidewire. In an anteroposterior image, the 2 osteotomy guidewires should completely obscure one another. With the osteotomy guidewires functioning as a cutting block and retractors secured along the anterior and posterior aspects of the femur, an oscillating saw with at least a 2-cm wide blade is inserted at the proximal surface of the guidewire(s) and is used to create the osteotomy. During passage of the saw blade and later of the osteotome, only the thinnest edge of the cutting device should be apparent on anteroposterior imaging. This step ensures correct sagittal orientation of the osteotomy. The saw is used to penetrate the lateral third of the femur. A large osteotome is inserted into the osteotomy site and is used to propagate the osteotomy through the anterior and posterior cortices of the femur and to within 1 cm of the medial cortex. A medial hinge is left intact to preserve stability of the osteotomy. Fluoroscopic imaging and an electrocautery cord as a “plumb line” can be used to approximate the mechanical axis and thus estimate the amount of correction required. The electrocautery cord is held against the skin overlying the center of the femoral head, which is determined by using anteroposterior fluoroscopic imaging (Fig. 2A). The “plumb line” is dropped distally to the center of the talus, as confirmed using fluoroscopy (Fig. 2B). It is critical to have the “plumb line” tensioned and centered within the femoral head and talus on anteroposterior fluoroscopic images. A fluoroscopic image of the knee is obtained; the “plumb line” on anteroposterior fluoroscopic image represents the mechanical axis of the extremity. A lamina spreader is passed centrally within the osteotomy site and opened to the desired correction, usually with the weight-bearing axis passing through the center of the tibial spines or slightly medial in a valgus knee (Fig. 2C and D). Once the desired correction is achieved, the osteotomy site is filled with tricortical and cancellous autograft obtained from the iliac crest. Although bone grafting may not be necessary in osteotomies less than 7.5 mm, delayed union, nonunion, and fixation failure may ensue if bone grafting is not used in osteotomies greater than 7.5 mm.16 Fixed-angled devices are most commonly used as fixation devices to secure the osteotomy. We prefer to use a 901 blade plate because this construct eliminates screw toggling, can minimize potential bone loss, and can be inserted distally within the metaphyseal bone (Fig. 3).
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Figure 2 The weight-bearing axis is determined by dropping a “plumb line” through the center of the femoral head (A) and ankle mortise (B). The osteotomy is opened and location of weight-bearing axis is visualized (C). The osteotomy should be adjusted until the weight-bearing axis is within the center of the tibial spines (D).
Preparation of the distal segment for blade insertion begins by passing a guidewire (1) just distal to the epicondylar axis and parallel to the joint line on anteroposterior fluoroscopic views and (2) centered between the anterior and posterior cortices on lateral fluoroscopic views. Using 2.5-mm drill through a parallel drill guide, 2 additional drill holes are created 3 mm anterior and posterior, respectively, and parallel to the guidewire. To ensure maintenance of osteotomy in the coronal and sagittal planes, the seating chisel must be precisely passed through these previously placed drill holes. The chisel should be slowly advanced and withdrawn after each 1 cm to prevent incarcerating the chisel.17 When selecting the appropriate blade length, the blade should be left 1 cm short of the medial femoral cortex, which can be easily penetrated because of its steep inclination.18 The blade plate is inserted with the plate abutting the lateral femoral cortex. The screw holes proximal to the osteotomy site are filled using fully threaded 4.5-mm screws
passed bicortically through the distal femur. Once the plate is secured, adequacy of the correction should be confirmed using anteroposterior and lateral fluoroscopic images. Once adequate hemostasis has been obtained, we prefer to close the wound without a drain. The extremity is placed into a hinged knee brace locked in extension. Patients are usually hospitalized for a minimum of 1 night to allow for management through appropriate analgesic regimen and neurovascular monitoring and are placed on chemoprophylaxis using low-molecular-weight heparin starting on postoperative day 1 and extending until mobilization ensues.
Opening-Wedge Medial High Tibial Osteotomy for Varus Malalignment Patients are positioned supine on a radiolucent table that permits fluoroscopic imaging of the entire extremity from hip
Osteotomy in cartilage resurfacing procedures
Figure 3 The 901 blade plate requires meticulous technique during insertion, but its advantages include avoidance of screw toggling, minimal bone loss, and potential for distal insertion.
to ankle. Regional anesthesia should be avoided to allow for close neurovascular monitoring postoperatively. A thigh tourniquet is applied but not inflated throughout the case unless hemostasis cannot be maintained. Although the tourniquet may limit blood loss, inflation of the tourniquet may hinder identification of an iatrogenic vascular injury; therefore, its use is restricted, especially during creation of the osteotomy. Once the extremity is surgically prepared, a radiolucent bump is placed beneath the operative calf to facilitate intraoperative fluoroscopic imaging and avoid interference of the contralateral limb on lateral views. Furthermore, slight knee flexion afforded by the bump relaxes the medial gastrocnemius and aids in retractor placement during the osteotomy and in aligning the tibial slope on anteroposterior fluoroscopic images. A proposed longitudinal incision is marked 2 cm medial to the tibial tubercle. The medial incision begins at the medial joint line and extends distally approximately 6 cm. The skin and subcutaneous tissue are sharply incised just medial to the extensor mechanism. The periosteum of the anteromedial tibia is dissected off the anteromedial tibia adjacent to the medial border of the tibial tubercle. The pes anserinus tendons are subperiostally dissected from their medial attachment and retracted posterior to the level of the anterior portion of the medial collateral ligament. The superficial medial collateral
257 ligament is elevated proximally to gain access to the complete proximal portion of the medial tibia. Elevation of the anterior fibers of the distal superficial medial collateral ligament insertion may be required to provide adequate exposure. To avoid potential valgus instability, care should be taken to limit dissection of the distal insertion of the superficial medial collateral ligament, which measures approximately 15 mm in width.19 The posterior border of the tibia is identified and a Hohmann retractor is inserted beneath the medial collateral ligament and medial head of the gastrocnemius and lodged along the posterior border of the tibia to protect the neurovascular structures. A small subperiosteal dissection is made just distal to the patellar tendon attachment at the area where the anterior part of the osteotomy would cross. Dissection only needs to be large enough to accommodate a small Hohmann retractor. The retractor is placed beneath the periosteum and traction is held anteriorly and proximally to protect the periosteum and distal insertion of the patellar tendon during creation of the osteotomy anteriorly. Once adequate exposure has been obtained, orthogonal fluoroscopic images of the knee are used to identify the slope of the tibial plateau. A true anteroposterior view in which the anterior and posterior margins of the tibial plateau completely obscure each other can be obtained by orienting the x-ray beam parallel to the joint line.20 A distal osteotomy guidewire is inserted into the anteromedial tibia roughly 1 cm posterior to the medial tibial tubercle and 4 cm distal to the medial joint line using a true anteroposterior view. The guidewire is advanced proximally toward the superior aspect of the proximal tibia-fibula joint. If the guidewire is passed too proximally, injury to the posterior cruciate ligament insertion and fracture into the lateral tibial plateau can occur during the creation of the osteotomy.21 Once satisfactory position of the initial osteotomy guidewire is inserted, a second osteotomy guidewire is passed at least 1 cm posteriorly and parallel to the more anterior osteotomy guidewire. The 2 osteotomy guidewires should completely obscure one another in a true anteroposterior image (Fig. 4). Perfect lateral fluoroscopic images, defined by completely overlapping condyles, should be obtained to confirm that the guidewires are parallel to the slope of the proximal tibia. With the osteotomy guidewires functioning as a cutting block and retractors secured along the anterior and posterior aspects of the tibia, an oscillating saw with at least a 2-cm wide blade is inserted at the distal surface of the guidewires and is used to create the osteotomy. The saw is advanced to the lateral third of the tibia. Care is taken to avoid penetration of the lateral cortex of the tibia and the lateral half of the anterior and posterior cortices. It is imperative that a retractor is placed directly against the posterior tibial cortex when penetrating the posterior cortex. This retractor protects the posterior neurovascular structures from potential iatrogenic injury. To ensure an osteotomy that parallels the guidewires and thus the tibial slope, only the thin edge of the saw blade should be apparent on anteroposterior images during creation of the bone cut. Irrigation of the saw blade with room temperature saline can prevent the counter heat generated during the osteotomy and limit potential thermal necrosis of the bone edges.22 The saw is
258
Figure 4 Guidewires should completely obscure each other on true anteroposterior radiographs to ensure preservation of the correct tibial slope.
replaced by a large osteotome, which is used to complete the cuts on the anterior and posterior cortices. In our experience, a large osteotome is less likely to plunge. The osteotomy is advanced to within 1 cm of the lateral tibial cortex. Penetration of the lateral cortex can render the osteotomy unstable and lead to potential nonunion or malunion or both.1 To determine the eventual amount of correction, the mechanical axis of the extremity is estimated using fluoroscopy, as described earlier. One or more lamina spreaders or commercially available osteotomy spreaders are inserted into the osteotomy site to create balanced distraction. The spreaders open the osteotomy until the “plumb line” created using the electrocautery and corresponding to the weight-bearing axis traverses or is lateral to the lateral tibial spine (Fig. 5). Sometimes, a relaxing incision within the medial collateral ligament adjacent is required to allow the osteotomy to distract adequately.23 Once the osteotomy has been satisfactorily distracted, lateral fluoroscopic images are obtained to confirm that the sagittal slope of the tibia has been retained. If the anterior tibia has been preferentially distracted, increased posterior slope would be created and may cause anterior tibial translation24 and redistribution of contact pressure into the posterior tibial plateau.25 Multiple fixation systems have been designed to stabilize osteotomy. Fixation systems are divided into fixed-angled locking plates (eg, TomoFix and proximal medial tibial locking plates, Synthes, West Chester, PA), plates with small wedges (eg, Puddu plate, Arthrex, Naples, FL), or wedges with locking
R.A. Gallo et al. screws (eg, iBalance HTO, Arthrex, Naples, FL). Fixed-angle locking plates have the advantage of preserving the coronal correction attained on radiographic hip-knee-ankle angles, whereas wedged systems more effectively prevent increases in posterior tibial slope.26 We prefer a 7-hole fixed-angle proximal medial locking plate because of ease of insertion (lamina spreader can often be retained during plate fixation) and less dissection of the superficial medial collateral ligament that is required. The plate is inserted with (1) horizontal section parallel to the joint line and beneath the superficial medial collateral ligament (if placing the plate beneath the medial collateral ligament requires too much dissection, the plate can be placed superficial to the ligament) and (2) longitudinal portion of the plate just in front of the anterior border of the medial collateral ligament. The plate should be as posteriorly placed as possible to avoid alteration of the slope and penetration of the posterior cortex. Fixation of the proximal segment is obtained using locking screws, whereas the screws within the distal segment are a combination of locking and nonlocking bicortical screws, which allow the plate to contour to the proximal tibia. The most distal screw is prepared and incompletely inserted initially to allow for plate manipulation, if necessary. The proximal screws are then inserted with the knee hyperextended to prevent the distal segment from flexing posteriorly and to prevent increasing of the posterior slope. The previously placed distal screw is secured followed by insertion of the remainder of the distal screws. Confirmation of the adequacy of the correction and avoidance of sagittal slope alteration should be made using anteroposterior and lateral fluoroscopic images or intraoperative radiographs (Fig. 6).
Figure 5 During a high tibial osteotomy, the “plumb line” should traverse or pass just lateral to the lateral tibial spine to adequately unload the medial compartment.
Osteotomy in cartilage resurfacing procedures
259
Figure 6 Anteroposterior (A) and lateral (B) radiographs obtained postoperatively demonstrate correction of deformity with alterations in sagittal plane geometry.
The osteotomy site is packed with bone graft. A variety of bone graft options exist, and these include structural and nonstructural autografts and allografts. Although graft choice is personalized for each patient, our preferred graft is a mixture of an osteoconductive allograft (eg, 30 cc of cancellous chips) and osteoinductive bone graft substitute (eg, demineralized bone matrix) to maximize the potential for bone formation without donor-site morbidity. Before closure, a thorough vascular examination is performed. The dorsum of the foot, which was surgically prepared in sterile conditions, at the beginning of the case and, if necessary, can be re-prepared, is exposed and evaluated for any evidence of vascular compromise. Prior to proceeding, a dorsalis pedis or posterior tibialis pulse should be confirmed by palpation or audibly using a Doppler probe. In addition, the compartments are assessed to confirm compressibility. We do not routinely release the anterior or lateral compartments, but fasciotomies should be considered if the compartments are full. Once adequate hemostasis has been obtained, we prefer to close the wound without a drain. The extremity is placed into a hinged knee brace locked in extension. Patients are usually hospitalized for a minimum of 1 night to allow for appropriate analgesic regimen and neurovascular monitoring and placed on chemoprophylaxis using low-molecular-weight heparin starting on postoperative day 1 and extending until mobilization ensues.
Literature Results Multiple studies have been published over the years documenting the clinical outcomes following osteotomy. Tables 1 and 2 outline selected clinical outcomes from studies following medial opening-wedge high tibial and lateral opening-wedge distal femoral osteotomy, respectively. An magnetic resonance imaging study by Parker et al39 suggested that unloading a compartment has the potential for recovery of damaged articular cartilage in that compartment. However, most studies report series of patients whose primary indication for surgery was unicompartmental osteoarthritis and not isolated cartilage defects with malalignment. Unloading osteotomy has become an important adjunct to cartilage resurfacing procedures, especially in patients with a unipolar chondral lesion involving an overloaded compartment. Favorable outcomes have been reported for combined osteotomy and cartilage resurfacing procedures, such as microfracture, osteochondral autografts, and autologous chondrocyte implantation. Individual cohort studies outlining outcomes of osteotomy combined with specific cartilage resurfacing procedures have been outlined in Table 3. Microfracture and osteochondral autograft procedures are usually restricted to small unipolar lesions measuring less than 2-3 cm², whereas cartilage defects greater than 2-3 cm² are treated with either autologous chondrocyte implantation or
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260 Table 1 Recent Selected Studies on Outcomes Following Medial Opening-Wedge Proximal Tibial Osteotomy Number of Subjects
Mean Follow-up in Years (Range)
Average Age (Range)
Koshino et al27 Kolb et al28 DeMeo et al29
21
6.6
66.6
49 20
4.3 8.3
49 49.4 (36-67)
Haviv et al30
22
6.3 (⫾2.3)
44 (⫾13.7)
Hooper et al31 Bonasia et al32
36
Minimum 4 y
45 (21-57)
99
4.3 (⫾2.0)
54.5 (⫾9.2)
Saito et al33
78
6.5 (5-10)
68 (49-82)
References
Outcomes Improvement of American Knee score at followup ¼ 34.1 points Survivorship ¼ 92% Survivorship ¼ 70% Improvement of Lysholm score at follow-up ¼ 28.8 points Improvement of HSS Knee score at follow-up ¼ 10.9 points Survivorship ¼ 91% Improvement of Oxford Knee score at follow-up ¼ 14.8 points Survivorship ¼ 69% Survivorship at 5 y ¼ 99% Survivorship at 7.5 y ¼ 76% Improvement of Knee Society score at followup ¼ 24.9 points Improvement of WOMAC score at follow-up ¼ 25.4 points Improvement of Knee Society score at followup ¼ 38.5 points
HSS, Hospital for Special Surgery; WOMAC, Western Ontario and McMaster Universities Arthritis Index.
osteochondral allograft.43 Owing to the poor results in cartilage resurfacing procedures performed in “kissing” lesions involving corresponding femoral and tibial surfaces, osteotomy alone is preferred for this population of patients with bipolar chondral defects. Although most authors recognize the importance of unloading the affected compartment during cartilage resurfacing procedures,9 there is a relative scarcity of controlled studies to support this claim. Most of the available data on cartilage restoration procedures combined with osteotomy are buried in data sets evaluating the outcomes of those undergoing the cartilage procedure. A recent study by Bode et al44 was among the first studies to evaluate the effects of osteotomy on the
success or failure of cartilage resurfacing. In this study, 43 subjects with cartilage defects of the medial femoral condyle and varus deformities less than 51 underwent autologous cartilage transplantation with or without high tibial osteotomy. Those who underwent a combined autologous chondrocyte transplantation and high tibial osteotomy experienced better clinical outcomes and had a significantly reduced rate of reintervention (10.5% vs 41.7%) than those who had isolated autologous chondrocyte implantation.44 A recent systemic review attempted to determine the value of cartilage resurfacing in improving outcomes following osteotomy. A total of 4344 knees (57 studies) on which isolated high tibial osteotomy was performed were compared
Table 2 Recent Selected Studies on Outcomes Following Lateral Opening-Wedge Distal Femoral Osteotomy Number of Knees
Mean Follow-up in Years (Range)
Average Age (Range)
Das et al
12
6.2 (4.3-7.4)
55 (46-71)
Zarrouk et al35
22
4.5
53 (27-66)
References 34
Thein et al36
7
6.5 (⫾1.5)
46.7 (⫾10.7)
Dewilde et al37
19
5.7 (2.6-10.6)
47 (30-51)
Saithna et al38
21
4.5 (1.6-9.2)
41 (28-58)
IKDC, International Knee Documentation Committee.
Outcomes Survivorship ¼ 83.3% Improvement of HSS score at follow-up ¼ 14 points Survivorship at 8 y ¼ 91% Improvement in International Knee Society score at follow-up ¼ 25 points Survivorship ¼ 100% Improvement of Oxford Knee score at follow-up ¼ 12.9 points Survivorship at 7 y ¼ 82% Improvement of International Knee Society Knee score at follow-up ¼ 35 points Survivorship at 5 y ¼ 79% Improvement of IKDC score at follow-up ¼ 16.2 points Improvement of Lysholm score at follow-up ¼ 5.5 points
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261
Table 3 Studies on Outcomes Following Combined High Tibial Osteotomy and Cartilage Resurfacing Procedure Number Resurfacing Technique References of Knees 40
Mean Follow-up in Years (Range)
Average Age (Range)
Microfracture
Sterett et al
106
6.8 (1.6-9.7)
52 (30-71)
Matrix-induced autologous chondrocyte implantation
Bauer et al41
18
5
47 (34-58)
Osteochondral autologous transfer
Minzlaff et al42
74
7.5
38 (19-62)
Outcomes Survivorship at 5 y ¼ 97% Survivorship at 7 y ¼ 91% Improvement of Lysholm score at follow-up ¼ 8 points Survivorship at 5 y ¼ 88% Improvement in KOOS pain score at follow-up ¼ 25 points Improvement in KOOS symptoms score at follow-up ¼ 10 points Survivorship at 7 y ¼ 93% Survivorship at 8.5 y ¼ 90% Improvement in Lysholm score at follow-up ¼ 33 points
KOOS, Knee Injury and Osteoarthritis Outcome Score.
with 399 knees (9 studies) on which high tibial osteotomy plus articular cartilage surgery was performed based on survival and clinical and radiographic outcomes.45 Although methodological variation in outcome score and length of follow-up among selected studies precluded meaningful evaluation of functional outcome, those undergoing a cartilage procedure in addition to high tibial osteotomy had a significantly higher 5-year survival rate (97.7% vs 92.4%) than those who had isolated high tibial osteotomy.45 However, both groups demonstrated deterioration of clinical outcomes with time (up to 10 years follow-up).45 Although limited, the current available literature supports the use of concomitant unloading osteotomy in improving the success rates of cartilage resurfacing procedures. Shifting the weight-bearing axis away from the overloaded compartment appears to improve the biomechanical milieu and thus increase the longevity of the cartilage resurfacing procedure. Failure to correct may expose cartilage graft or reparative tissue to excessive forces and premature failure. Therefore, any patient contemplating a cartilage resurfacing procedure should be evaluated for malalignment and, if present, an adjunctive unloading osteotomy should be considered.
Complications Knee osteotomies are demanding procedures that require meticulous surgical technique to avoid serious perioperative complications. Complications can be divided into perioperative complications, such as on neurovascular injury and fracture extending intra-articularly or through the far cortex (lateral cortex during a high tibial, opening-wedge osteotomy and medial cortex during distal femoral, opening-wedge osteotomy) during the osteotomy, and long-term complications that include nonunion, loss of correction, patella baja, arthrofibrosis, and prominent hardware. The rates of many long-term complications have decreased over recent years because of advances in fixation hardware and early postoperative range of motion.
Among the intraoperative complications, popliteal artery transection is a relatively rare, but potentially limb-threatening, injury described during knee osteotomy. During high tibial osteotomy, the popliteal artery is located 13-14 mm behind the posterior tibial cortex roughly 35 mm lateral to the posteromedial starting point of the osteotomy.46 Therefore, during creation of the osteotomy, a retractor should be inserted along the posterior tibial cortex and must traverse at least the medial 4 cm of the posterior tibia to provide adequate protection of the popliteal artery. Extension of the osteotomy intra-articularly or through the far cortex can result in articular surface incongruity or instability and subsequent nonunion of the osteotomy, respectively. Both entities must be recognized and addressed intraoperatively with appropriate fixation to limit potential disability. Risk of fracture propagation intra-articularly during high tibial osteotomy can be minimized by carrying the apex of the osteotomy within 1 cm of the lateral cortex and 1.5 cm from the lateral joint line.1 To prevent fracture of the far cortex, gradual opening of the osteotomy has been advised to allow for stress relaxation of the intact far cortex.1 Despite increased surgical times, complications rates of combining realignment procedures with other cartilage restoration procedures are not higher than those obtained with performing osteotomy alone.47 In a study analyzing complications in a cohort of patients undergoing combined osteotomy and reconstructive procedure, complications occurred in 37%, including 20% rate of major complications.47
Future of Technique The indications for realignment osteotomies will continue to be redefined as the technology of knee arthroplasty and cartilage restoration procedures evolves and the outcomes improve. With improvements in the durability of bearing surfaces and longevity of total knee arthroplasty, the need for isolated realignment osteotomies that have a limited lifespan will likely diminish. Technological advances in cartilage resurfacing
262 procedures may eventually allow for more durable repairs and therefore increase the indications for cartilage restoration. Consequently, osteotomies that unload the repair will continue to be a popular adjunct to improve the outcomes of these procedures. Advances in technology may result in less invasive, safer osteotomies that provide more precise corrections. Instrumented systems, such as the iBalance (Arthrex, Naples, FL), provide instrumentation that theoretically limits dissection, provides protection of the neurovascular bundle posterior, and assists in the creation of accurate cuts.48 Limited data are currently available on the outcomes following osteotomies using these systems.
Rehabilitation Protocol The goals of early rehabilitation are restoration of range of motion and minimizing quadriceps atrophy through isometric exercises. During the hospital stay, a continuous passive motion machine is applied to maximize passive range of motion. Once discharged, patients are instructed on passive motion exercises accomplished by placing the operative extremity off the side of the bed with the unaffected leg directly beneath for support. Patients are limited to toe-touch weight-bearing with a hinged knee brace and crutches for a minimum of 6-8 weeks. If healing of the osteotomy and maintenance of the correction is confirmed on radiographs, gradual advancement to full weight-bearing by 8-10 weeks is permitted. Formal physical therapy is generally initiated at 6 weeks postoperatively.
References 1. Wright JM, Crockett HC, Slawski DP, et al: High tibial osteotomy. J Am Acad Orthop Surg 13:279-289, 2005 2. Jackson JP, Waugh W: Tibial osteotomy for osteoarthritis of the knee. Proc R Soc Med 53:888, 1960 3. Coventry MB: Osteotomy about the knee for degenerative and rheumatoid arthritis: Indications, operative technique, and results. J Bone Joint Surg Am 55:23-48, 1973 4. Insall J, Shoji H, Mayer V: High tibial osteotomy: A five-year evaluation. J Bone Joint Surg Am 56:1397-1405, 1974 5. Rinonapoli E, Mancini GB, Corvaglia A, et al: Tibial osteotomy for varus gonarthrosis: A 10- to 21-year follow-up study. Clin Orthop Relat Res 353:185-193, 1998 6. Yasuda K, Majima T, Tsuchida T, et al: A ten- to 15-year follow-up observation of high tibial osteotomy in medial compartment osteoarthritis. Clin Orthop Relat Res 282:186-195, 1992 7. Berman AT, Bosacco SJ, Kirshner S, et al: Factors influencing long-term results in high tibial osteotomy. Clin Orthop Relat Res 272:192-198, 1991 8. Insall JN, Jospeh DM, Msika C: High tibial osteotomy for varus gonarthrosis: A long-term follow-up study. J Bone Joint Surg Am 66:1040-1048, 1984 9. Gomoll AH, Farr J, Gillogly SD, et al: Surgical management of articular cartilage defects of the knee. J Bone Joint Surg Am 92:2470-2490, 2010 10. Miller BS, Downie B, McDonough EB, et al: Complications after medial opening wedge high tibial osteotomy. Arthroscopy 25:639-646, 2009 11. van Houten AH, Heesterbeek PJ, van Heerwaarden RJ, et al: Medial open wedge high tibial osteotomy: Can delayed or nonunion be predicted? Clin Orthop Relat Res 472:1217-1223, 2014 12. Wolcott M, Traub S, Efird C: High tibial osteotomies in the young active patient. Int Orthop 34:161-166, 2010
R.A. Gallo et al. 13. Leone JM, Hanssen AD: Osteotomy about the knee: American perspective. In: ed 4 Scott WN (ed): Surgery of the Knee, 2. Philadephia, Elsevier, [Chapter 7] 1301-1320, 2006. 14. Coventry MB: Upper tibial osteotomy for gonarthrosis: The evolution of the operation in the last 18 years and long term results. Orthop Clin North Am 10:191-210, 1979 15. Dugdale TW, Noyes FR, Styer D: Preoperative planning for high tibial osteotomy: The effect of lateral tibiofemoral separation and tibiofemoral length. Clin Orthop Relat Res 274:248-264, 1992 16. Puddu G, Cipolla M, Cerullo G, et al: Which osteotomy for a valgus knee? Int Orthop 34:239-247, 2010 17. Whittle AP, Wood GW: Fractures of the lower extremity. In: ed 10 Canale ST (ed): Campbell’s Operative Orthopaedics, 3. Philadephia, Mosby, [Chapter 5] 2725-2873, 2003. 18. Malkani AL, Helfet DL: Blade fixation of supracondylar femur fractures. Tech Orthop 9:203, 1995 19. Liu F, Yue B, Gadikota HR, et al: Morphology of the medial collateral ligament of the knee. J Orthop Surg Res 5:69, 2010 20. Moore TM, Harvey JP: Roentgenographic measurement of tibial plateau depression due to fracture. J Bone Joint Surg Am 56:155-160, 1974 21. Vanadurongwan B, Siripisitsak T, Sudjai N, et al: The anatomical safe zone for medial opening wedge high tibial osteotomy. Singapore Med J 54:102-104, 2013 22. Krause WR, Bradbury DM, Kelly JE, et al: Temperature elevations in orthopaedic cutting operations. J Biomech 15:267-275, 1982 23. Agneskirchner JD, Hurschler C, Wrann CD, et al: The effects of valgus medial opening wedge high tibial osteotomy in the articular cartilage pressure of the knee: A biomechanical study. Arthroscopy 23:852-861, 2007 24. Giffin JR, Vogrin TM, Zantop T, et al: Effects of increasing tibial slope on the biomechanics of the knee. Am J Sports Med 32:376-382, 2004 25. Rodner CM, Adams DJ, Diaz-Doran V, et al: Medial opening wedge tibial osteotomy and the sagittal plane: The effect of increasing tibial slope on tibiofemoral contact pressure. Am J Sports Med 34:1431-1441, 2006 26. Kim MK, Ha JK, Lee DW, et al: No correction angle loss with stable plates in open-wedge high tibial osteotomy. Knee Surg Sports Traumatol Arthrosc 2014; [Epub ahead of print] 27. Koshino T, Murase T, Saito T: Medial opening-wedge high tibial osteotomy with use of porous hydroxyapatite to treat medial compartment osteoarthritis of the knee. J Bone Joint Surg Am 85-A:78-85, 2003 28. Kolb W, Guhlmann H, Windisch C, et al: Opening-wedge high tibial osteotomy with a locked low-profile plate. J Bone Joint Surg Am 91:2581-2588, 2009 29. DeMeo PJ, Johnson EM, Chiang PP, et al: Midterm follow-up of openingwedge high tibial osteotomy. Am J Sports Med 38:2077-2084, 2010 30. Haviv B, Bronak S, Thein R, et al: Mid-term outcome of opening-wedge high tibial osteotomy for varus arthritic knees. Orthopedics 35: e192-e196, 2012 31. Hooper NM, Schouten R, Hooper GJ: The outcome of bone substitute wedges in medial opening high tibial osteotomy. Open Orthop J 7:373-377, 2013 32. Bonasia DE, Dettoni F, Sito G, et al: Medial opening wedge high tibial osteotomy for medial compartment overload/arthritis in the varus knee: Prognostic factors. Am J Sports Med 42:690-698, 2014 33. Saito T, Kumagai K, Akamatsu Y, et al: Five- to ten-year outcome following medial opening-wedge high tibial osteotomy with rigid plate fixation in combination with an artificial bone substitute. Bone Joint J 96-B:339-344, 2014 34. Das D, Sijbesma T, Hoekstra H, et al: Distal femoral opening-wedge osteotomy for lateral compartment osteoarthritis of the knee. Open Access Surg 1:25-29, 2008 35. Zarrouk A, Bouzidi R, Karray B, et al: Distal femoral varus osteotomy outcome: Is associated femoropatellar osteoarthritis consequential? Orthop Traumatol Surg Res 96:632-636, 2010 36. Thein R, Bronak S, Thein R, et al: Distal femoral osteotomy for valgus arthritic knees. J Orthop Sci 17:745-749, 2012 37. Dewilde TR, Dauw J, Vandenneucker H, et al: Opening wedge distal femoral varus osteotomy using the Puddu plate and calcium phosphate bone cement. Knee Surg Sports Traumatol Arthrosc 21:249-254, 2013
Osteotomy in cartilage resurfacing procedures 38. Saithna A, Kundra R, Getgood A, et al: Opening wedge distal femoral varus osteotomy for lateral compartment osteoarthritis in the valgus knee. Knee 21:172-175, 2014 39. Parker DA, Beatty KT, Giuffre B, et al: Articular cartilage changes in patients with osteoarthritis after osteotomy. Am J Sports Med 39:1039-1045, 2011 40. Sterett WI, Steadman JR, Huang MJ, et al: Chondral resurfacing and high tibial osteotomy in the varus knee: Survivorship analysis. Am J Sports Med 38:1420-1424, 2010 41. Bauer S, Khan RJ, Ebert JR, et al: Knee joint preservation with combined neutralising high tibial osteotomy (HTO) and matrix-induced autologous chondrocyte implantation (MACI) in younger patients with medial knee osteoarthritis: A case series with prospective clinical and MRI follow-up over 5 years. Knee 19:431-439, 2012 42. Minzlaff P, Feucht MJ, Saier T, et al: Osteochondral autologous transfer combined with valgus high tibial osteotomy: Long-term results and survivorship analysis. Am J Sports Med 41:2325-2332, 2013 43. Camp CL, Stuart MJ, Krych AJ: Current concepts of articular cartilage restoration techniques in the knee. Sports Health 6:265-273, 2014
263 44. Bode G, Schmal H, Pestka JM, et al: A non-randomized controlled clinical trial on autologous chondrocyte implantation (ACI) in cartilage defects of the medial femoral condyle with or without high tibial osteotomy in patients with varus deformity of less than 51. Arch Orthop Trauma Surg 133:43-49, 2013 45. Harris JD, McNeilan R, Siston RA, et al: Survival and clinical outcome of isolated high tibial osteotomy and combined biological knee reconstruction. Knee 20:154-161, 2013 46. Lee YS, Lee BK, Kim WS, et al: Sagittal and coronal plane location of the poplital artery in the opening-wedge high tibial osteotomy. Knee Surg Sports Traumatol Arthrosc 2013 [Epub ahead of print] 47. Willey M, Wolf BR, Kocaglu B, et al: Complications associated with realignment osteotomy of the knee performed simultaneously with additional reconstructive procedures. Iowa Orthop J 30:55-60, 2010 48. Scordino LE, DeBerardino TM: Surgical treatment of osteoarthritis in the middle-aged athlete: New horizons in high tibial osteotomies. Sports Med Arthrosc 21:47-51, 2013
Historical Perspective
O
steotomy has been used for more than a century to correct acquired and posttraumatic deformities around the knee.1 However, it was not until 1960 that the concept of osteotomy was applied to the treatment of knee osteoarthritis.2 Interestingly, in that sentinel study, Jackson encouraged a distal femoral osteotomy for the treatment of genu valgum and a proximal tibial osteotomy for genu varum. Over the next 2 decades, closed high tibial osteotomies, as popularized by Coventry3 and Insall et al,4 became a mainstay of treatment for both varus and valgus gonarthrosis. The interest in osteotomy waned during the 1980s and 1990s secondary to (1) design modifications and resultant improved outcomes following total and unicompartment knee arthroplasty, and (2) emergence of long-term follow-up studies after osteotomy. During this time period, multiple reports surfaced documenting a dramatic decline in outcome despite promising results within the first 5 years. Unsatisfactory outcomes, including conversion to total knee arthroplasty, Department of Orthopaedics, Bone and Joint Institute, Milton S. Hershey Medical Center, Pennsylvania State University College of Medicine, Hershey, PA. Neither the author nor an affiliated institute has received (or agreed to receive) from a commercial entity something of value (exceeding the equivalent of US$500) related in any way to this manuscript. Address reprint requests to Robert A. Gallo, MD, Department of Orthopaedics, Bone and Joint Institute, Milton S. Hershey Medical Center, Pennsylvania State University College of Medicine, 30 Hope Dr, Hershey, PA. E-mail: [email protected]
http://dx.doi.org/10.1053/j.oto.2014.05.005 1048-6666/& 2014 Elsevier Inc. All rights reserved.
occurred in 37%-63% of patients who were followed up beyond 10 years after osteotomy.5-8 The realization that osteotomy is often a temporizing procedure before a total knee arthroplasty also prompted a paradigm shift away from closing-wedge osteotomies and toward openingwedge osteotomies, which can maintain bone stock. Although opening-wedge high tibial osteotomy has become an increasingly popular treatment for varus malalignment, distal openingwedge osteotomy is a more common surgical treatment for correcting valgus malalignment because most of the deformity is usually within the distal femur and a lateral opening-wedge high tibial osteotomy is limited by the fibula. With the advent of cartilage restoration procedures, improvements in fixation hardware, and viable bone graft substitutes, there has been renewed popularity in knee osteotomies. Knee osteotomies have become a necessary tool in the armamentarium for surgeons performing cartilage restoration procedures or treating young, active individuals with arthritic change and malalignment who wish to maintain a sporting lifestyle.
Indications and Contraindications Realignment osteotomies should be considered to unload symptomatic articular cartilage maladies, femoral or tibial, associated with malalignment. Historically, the primary indication for realignment procedures has been isolated unicompartment osteoarthritis in a malaligned knee. Young, high-demand individuals with symptomatic unicompartmental grade III 253
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254 osteoarthritis and malalignment are the ideal candidates for an unloading osteotomy. However, the degree of osteoarthritis and age are just 2 factors to consider when deciding to proceed with realignment osteotomy. Desired activity levels, expected outcomes, and other potential benefits and risks following both osteotomy and knee arthroplasty should be weighed and discussed with each patient to determine if realignment osteotomy is the preferred procedure to help each patient optimize his or her function. A realignment osteotomy should be considered in each patient undergoing a cartilage resurfacing procedure and having a weight-bearing axis that passes through or more peripherally within the compartment than the articular cartilage lesion (Fig. 1). We are more aggressive about performing an osteotomy to unload the affected compartment if there is an asymmetric malalignment, such that the affected compartment has a higher degree of deformity. Failure to address the malalignment theoretically subjects the cartilage repair to mechanical overload and premature failure. For a realignment osteotomy to produce a successful outcome, the articular cartilage and overall milieu of the compartment that the weight-bearing axis is shifted toward must be adequate to accept the increased load. Therefore, the
degeneration of the articular cartilage in the opposite compartment is a contraindication to realignment osteotomy. Similarly, owing to the potential of continued pain in other regions of the knee or continued poor function, those with patellofemoral arthritis, nonconcordant pain, ongoing infection, range of motion less than 901, and inflammatory arthritis are not usually considered for osteotomies that realign the mechanical axis.9 Although these are not absolute contraindications to realignment osteotomy, body mass index greater than 35 kg/m2 and tobacco smoking pose increased risk to loss of angular correction and nonunion of the graft, respectively10,11; therefore, osteotomy is not recommended until these factors are corrected. Finally, realignment osteotomies can produce cosmetic deformities, especially in cases where overcorrection is desired. Patients who are unwilling to accept the anticipated appearance are not appropriate for a realignment osteotomy.
Preoperative Planning The assessment of alignment begins with a full-length standing anteroposterior radiograph. An adequate full-length radiograph should (1) be obtained with double-leg stance, (2) include
Figure 1 Bilateral standing full-length radiographs of the extremity are obtained in patients with focal full-thickness chondral defects (A) who are contemplating undergoing an articular cartilage restoration procedure. Unloading osteotomy should be considered when the weight-bearing axis passes through the defect (B), and especially, when the affected compartment has more pronounced malalignment.
Osteotomy in cartilage resurfacing procedures the entire femoral head and ankle mortise, and (3) be taken with the knee slightly flexed (roughly 51) to avoid abnormal varus recurvatum.12 The weight-bearing axis is drawn from the center of the femoral head to the center of the ankle mortise, and its intersection on the tibia provides a rough estimate of the amount of correction required. We prefer medial opening-wedge high tibial osteotomy to correct genu varum and lateral openingwedge distal femoral osteotomy for genu valgum. However, if excessive varus correction is required, a medial closing-wedge distal femoral osteotomy should be considered to avoid overstretching the peroneal nerve. The rule of thumb used to preoperatively predict the extent of the osteotomy is that, for each degree of desired correction, 1 mm of lengthening (opening-wedge) or resection (closingwedge) must be performed on the “near” cortex to achieve the appropriate correction.13 This estimation proves accurate only when width of the tibial flare measures 56 mm, which is far more narrow than normal.14 Alternately, Dugdale et al15 described a method to calculate the wedge necessary to achieve the desired correction. In this technique, 2 lines are drawn: one from the center of the femoral head to the desired location where the weight-bearing axis crosses the tibial joint line and the other line drawn from center of the ankle mortise to this same point on the tibia. The acute angle formed by the intersection of these 2 lines is the correction angle required. Wedge height can be calculated by using the angle of correction to recreate the osteotomy wedge on radiographs.13
Technique Opening-Wedge Lateral Distal Femoral Osteotomy for Valgus Malalignment Patients are placed supine on a radiolucent table with the pelvis and leg length leveled. A C-arm image intensifier is positioned on the opposite side and perpendicular to the long axis of the affected extremity. The entire lower extremity from pelvis to ankle should be unobstructed to permit fluoroscopic imaging during the procedure. Regional anesthesia is generally avoided to accommodate neurovascular monitoring postoperatively. A tourniquet is applied proximally in the thigh and, owing to the vascularity of the vastus lateralis, is inflated to 300 mm Hg throughout the case. A lateral skin incision is marked from the lateral joint line and extended proximally 10 cm along the palpable anterior border of the vastus lateralis. The skin and subcutaneous tissue are sharply incised to the level of the vastus lateralis. The interval between the rectus femoris and vastus lateralis is exploited. We choose the interval anterior to the vastus lateralis to limit the exposure and potential injury to the perforating vessels. A Hohmann retractor placed extracapsularly on the anterior tibia is used to retract the rectus femoris anteriorly. If possible, the capsule should not be violated. A second Hohmann retractor is inserted subperiosteally around the posterolateral femur. Slight knee flexion can relax the posterior musculature and facilitate retractor placement. Precise placement of the posterior retractor is crucial to protect posterior neurovascular structures.
255 Once the distal femur, including the lateral epicondyle, is exposed, a 2.0-mm guidewire is passed through the distal femoral metaphysis proximal to the proposed osteotomy site and perpendicular to the long axis of the femur. A second guidewire is inserted across the distal femur and acts as a frame of reference for the osteotomy. Under anteroposterior fluoroscopic imaging, the guidewire is passed at the proximal margin of the lateral epicondyle and parallel to the joint line. An osteotomy guidewire is inserted into the distal femoral metaphysis 2 fingerbreadths above the lateral epicondyle. The guidewire is advanced distally toward the superior aspect of the medial epicondyle. Once satisfactory position of the initial osteotomy guidewire is attained, and if the width of the distal femur can accommodate 2 wires, a second osteotomy guidewire may be passed parallel to the osteotomy guidewire. In an anteroposterior image, the 2 osteotomy guidewires should completely obscure one another. With the osteotomy guidewires functioning as a cutting block and retractors secured along the anterior and posterior aspects of the femur, an oscillating saw with at least a 2-cm wide blade is inserted at the proximal surface of the guidewire(s) and is used to create the osteotomy. During passage of the saw blade and later of the osteotome, only the thinnest edge of the cutting device should be apparent on anteroposterior imaging. This step ensures correct sagittal orientation of the osteotomy. The saw is used to penetrate the lateral third of the femur. A large osteotome is inserted into the osteotomy site and is used to propagate the osteotomy through the anterior and posterior cortices of the femur and to within 1 cm of the medial cortex. A medial hinge is left intact to preserve stability of the osteotomy. Fluoroscopic imaging and an electrocautery cord as a “plumb line” can be used to approximate the mechanical axis and thus estimate the amount of correction required. The electrocautery cord is held against the skin overlying the center of the femoral head, which is determined by using anteroposterior fluoroscopic imaging (Fig. 2A). The “plumb line” is dropped distally to the center of the talus, as confirmed using fluoroscopy (Fig. 2B). It is critical to have the “plumb line” tensioned and centered within the femoral head and talus on anteroposterior fluoroscopic images. A fluoroscopic image of the knee is obtained; the “plumb line” on anteroposterior fluoroscopic image represents the mechanical axis of the extremity. A lamina spreader is passed centrally within the osteotomy site and opened to the desired correction, usually with the weight-bearing axis passing through the center of the tibial spines or slightly medial in a valgus knee (Fig. 2C and D). Once the desired correction is achieved, the osteotomy site is filled with tricortical and cancellous autograft obtained from the iliac crest. Although bone grafting may not be necessary in osteotomies less than 7.5 mm, delayed union, nonunion, and fixation failure may ensue if bone grafting is not used in osteotomies greater than 7.5 mm.16 Fixed-angled devices are most commonly used as fixation devices to secure the osteotomy. We prefer to use a 901 blade plate because this construct eliminates screw toggling, can minimize potential bone loss, and can be inserted distally within the metaphyseal bone (Fig. 3).
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Figure 2 The weight-bearing axis is determined by dropping a “plumb line” through the center of the femoral head (A) and ankle mortise (B). The osteotomy is opened and location of weight-bearing axis is visualized (C). The osteotomy should be adjusted until the weight-bearing axis is within the center of the tibial spines (D).
Preparation of the distal segment for blade insertion begins by passing a guidewire (1) just distal to the epicondylar axis and parallel to the joint line on anteroposterior fluoroscopic views and (2) centered between the anterior and posterior cortices on lateral fluoroscopic views. Using 2.5-mm drill through a parallel drill guide, 2 additional drill holes are created 3 mm anterior and posterior, respectively, and parallel to the guidewire. To ensure maintenance of osteotomy in the coronal and sagittal planes, the seating chisel must be precisely passed through these previously placed drill holes. The chisel should be slowly advanced and withdrawn after each 1 cm to prevent incarcerating the chisel.17 When selecting the appropriate blade length, the blade should be left 1 cm short of the medial femoral cortex, which can be easily penetrated because of its steep inclination.18 The blade plate is inserted with the plate abutting the lateral femoral cortex. The screw holes proximal to the osteotomy site are filled using fully threaded 4.5-mm screws
passed bicortically through the distal femur. Once the plate is secured, adequacy of the correction should be confirmed using anteroposterior and lateral fluoroscopic images. Once adequate hemostasis has been obtained, we prefer to close the wound without a drain. The extremity is placed into a hinged knee brace locked in extension. Patients are usually hospitalized for a minimum of 1 night to allow for management through appropriate analgesic regimen and neurovascular monitoring and are placed on chemoprophylaxis using low-molecular-weight heparin starting on postoperative day 1 and extending until mobilization ensues.
Opening-Wedge Medial High Tibial Osteotomy for Varus Malalignment Patients are positioned supine on a radiolucent table that permits fluoroscopic imaging of the entire extremity from hip
Osteotomy in cartilage resurfacing procedures
Figure 3 The 901 blade plate requires meticulous technique during insertion, but its advantages include avoidance of screw toggling, minimal bone loss, and potential for distal insertion.
to ankle. Regional anesthesia should be avoided to allow for close neurovascular monitoring postoperatively. A thigh tourniquet is applied but not inflated throughout the case unless hemostasis cannot be maintained. Although the tourniquet may limit blood loss, inflation of the tourniquet may hinder identification of an iatrogenic vascular injury; therefore, its use is restricted, especially during creation of the osteotomy. Once the extremity is surgically prepared, a radiolucent bump is placed beneath the operative calf to facilitate intraoperative fluoroscopic imaging and avoid interference of the contralateral limb on lateral views. Furthermore, slight knee flexion afforded by the bump relaxes the medial gastrocnemius and aids in retractor placement during the osteotomy and in aligning the tibial slope on anteroposterior fluoroscopic images. A proposed longitudinal incision is marked 2 cm medial to the tibial tubercle. The medial incision begins at the medial joint line and extends distally approximately 6 cm. The skin and subcutaneous tissue are sharply incised just medial to the extensor mechanism. The periosteum of the anteromedial tibia is dissected off the anteromedial tibia adjacent to the medial border of the tibial tubercle. The pes anserinus tendons are subperiostally dissected from their medial attachment and retracted posterior to the level of the anterior portion of the medial collateral ligament. The superficial medial collateral
257 ligament is elevated proximally to gain access to the complete proximal portion of the medial tibia. Elevation of the anterior fibers of the distal superficial medial collateral ligament insertion may be required to provide adequate exposure. To avoid potential valgus instability, care should be taken to limit dissection of the distal insertion of the superficial medial collateral ligament, which measures approximately 15 mm in width.19 The posterior border of the tibia is identified and a Hohmann retractor is inserted beneath the medial collateral ligament and medial head of the gastrocnemius and lodged along the posterior border of the tibia to protect the neurovascular structures. A small subperiosteal dissection is made just distal to the patellar tendon attachment at the area where the anterior part of the osteotomy would cross. Dissection only needs to be large enough to accommodate a small Hohmann retractor. The retractor is placed beneath the periosteum and traction is held anteriorly and proximally to protect the periosteum and distal insertion of the patellar tendon during creation of the osteotomy anteriorly. Once adequate exposure has been obtained, orthogonal fluoroscopic images of the knee are used to identify the slope of the tibial plateau. A true anteroposterior view in which the anterior and posterior margins of the tibial plateau completely obscure each other can be obtained by orienting the x-ray beam parallel to the joint line.20 A distal osteotomy guidewire is inserted into the anteromedial tibia roughly 1 cm posterior to the medial tibial tubercle and 4 cm distal to the medial joint line using a true anteroposterior view. The guidewire is advanced proximally toward the superior aspect of the proximal tibia-fibula joint. If the guidewire is passed too proximally, injury to the posterior cruciate ligament insertion and fracture into the lateral tibial plateau can occur during the creation of the osteotomy.21 Once satisfactory position of the initial osteotomy guidewire is inserted, a second osteotomy guidewire is passed at least 1 cm posteriorly and parallel to the more anterior osteotomy guidewire. The 2 osteotomy guidewires should completely obscure one another in a true anteroposterior image (Fig. 4). Perfect lateral fluoroscopic images, defined by completely overlapping condyles, should be obtained to confirm that the guidewires are parallel to the slope of the proximal tibia. With the osteotomy guidewires functioning as a cutting block and retractors secured along the anterior and posterior aspects of the tibia, an oscillating saw with at least a 2-cm wide blade is inserted at the distal surface of the guidewires and is used to create the osteotomy. The saw is advanced to the lateral third of the tibia. Care is taken to avoid penetration of the lateral cortex of the tibia and the lateral half of the anterior and posterior cortices. It is imperative that a retractor is placed directly against the posterior tibial cortex when penetrating the posterior cortex. This retractor protects the posterior neurovascular structures from potential iatrogenic injury. To ensure an osteotomy that parallels the guidewires and thus the tibial slope, only the thin edge of the saw blade should be apparent on anteroposterior images during creation of the bone cut. Irrigation of the saw blade with room temperature saline can prevent the counter heat generated during the osteotomy and limit potential thermal necrosis of the bone edges.22 The saw is
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Figure 4 Guidewires should completely obscure each other on true anteroposterior radiographs to ensure preservation of the correct tibial slope.
replaced by a large osteotome, which is used to complete the cuts on the anterior and posterior cortices. In our experience, a large osteotome is less likely to plunge. The osteotomy is advanced to within 1 cm of the lateral tibial cortex. Penetration of the lateral cortex can render the osteotomy unstable and lead to potential nonunion or malunion or both.1 To determine the eventual amount of correction, the mechanical axis of the extremity is estimated using fluoroscopy, as described earlier. One or more lamina spreaders or commercially available osteotomy spreaders are inserted into the osteotomy site to create balanced distraction. The spreaders open the osteotomy until the “plumb line” created using the electrocautery and corresponding to the weight-bearing axis traverses or is lateral to the lateral tibial spine (Fig. 5). Sometimes, a relaxing incision within the medial collateral ligament adjacent is required to allow the osteotomy to distract adequately.23 Once the osteotomy has been satisfactorily distracted, lateral fluoroscopic images are obtained to confirm that the sagittal slope of the tibia has been retained. If the anterior tibia has been preferentially distracted, increased posterior slope would be created and may cause anterior tibial translation24 and redistribution of contact pressure into the posterior tibial plateau.25 Multiple fixation systems have been designed to stabilize osteotomy. Fixation systems are divided into fixed-angled locking plates (eg, TomoFix and proximal medial tibial locking plates, Synthes, West Chester, PA), plates with small wedges (eg, Puddu plate, Arthrex, Naples, FL), or wedges with locking
R.A. Gallo et al. screws (eg, iBalance HTO, Arthrex, Naples, FL). Fixed-angle locking plates have the advantage of preserving the coronal correction attained on radiographic hip-knee-ankle angles, whereas wedged systems more effectively prevent increases in posterior tibial slope.26 We prefer a 7-hole fixed-angle proximal medial locking plate because of ease of insertion (lamina spreader can often be retained during plate fixation) and less dissection of the superficial medial collateral ligament that is required. The plate is inserted with (1) horizontal section parallel to the joint line and beneath the superficial medial collateral ligament (if placing the plate beneath the medial collateral ligament requires too much dissection, the plate can be placed superficial to the ligament) and (2) longitudinal portion of the plate just in front of the anterior border of the medial collateral ligament. The plate should be as posteriorly placed as possible to avoid alteration of the slope and penetration of the posterior cortex. Fixation of the proximal segment is obtained using locking screws, whereas the screws within the distal segment are a combination of locking and nonlocking bicortical screws, which allow the plate to contour to the proximal tibia. The most distal screw is prepared and incompletely inserted initially to allow for plate manipulation, if necessary. The proximal screws are then inserted with the knee hyperextended to prevent the distal segment from flexing posteriorly and to prevent increasing of the posterior slope. The previously placed distal screw is secured followed by insertion of the remainder of the distal screws. Confirmation of the adequacy of the correction and avoidance of sagittal slope alteration should be made using anteroposterior and lateral fluoroscopic images or intraoperative radiographs (Fig. 6).
Figure 5 During a high tibial osteotomy, the “plumb line” should traverse or pass just lateral to the lateral tibial spine to adequately unload the medial compartment.
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Figure 6 Anteroposterior (A) and lateral (B) radiographs obtained postoperatively demonstrate correction of deformity with alterations in sagittal plane geometry.
The osteotomy site is packed with bone graft. A variety of bone graft options exist, and these include structural and nonstructural autografts and allografts. Although graft choice is personalized for each patient, our preferred graft is a mixture of an osteoconductive allograft (eg, 30 cc of cancellous chips) and osteoinductive bone graft substitute (eg, demineralized bone matrix) to maximize the potential for bone formation without donor-site morbidity. Before closure, a thorough vascular examination is performed. The dorsum of the foot, which was surgically prepared in sterile conditions, at the beginning of the case and, if necessary, can be re-prepared, is exposed and evaluated for any evidence of vascular compromise. Prior to proceeding, a dorsalis pedis or posterior tibialis pulse should be confirmed by palpation or audibly using a Doppler probe. In addition, the compartments are assessed to confirm compressibility. We do not routinely release the anterior or lateral compartments, but fasciotomies should be considered if the compartments are full. Once adequate hemostasis has been obtained, we prefer to close the wound without a drain. The extremity is placed into a hinged knee brace locked in extension. Patients are usually hospitalized for a minimum of 1 night to allow for appropriate analgesic regimen and neurovascular monitoring and placed on chemoprophylaxis using low-molecular-weight heparin starting on postoperative day 1 and extending until mobilization ensues.
Literature Results Multiple studies have been published over the years documenting the clinical outcomes following osteotomy. Tables 1 and 2 outline selected clinical outcomes from studies following medial opening-wedge high tibial and lateral opening-wedge distal femoral osteotomy, respectively. An magnetic resonance imaging study by Parker et al39 suggested that unloading a compartment has the potential for recovery of damaged articular cartilage in that compartment. However, most studies report series of patients whose primary indication for surgery was unicompartmental osteoarthritis and not isolated cartilage defects with malalignment. Unloading osteotomy has become an important adjunct to cartilage resurfacing procedures, especially in patients with a unipolar chondral lesion involving an overloaded compartment. Favorable outcomes have been reported for combined osteotomy and cartilage resurfacing procedures, such as microfracture, osteochondral autografts, and autologous chondrocyte implantation. Individual cohort studies outlining outcomes of osteotomy combined with specific cartilage resurfacing procedures have been outlined in Table 3. Microfracture and osteochondral autograft procedures are usually restricted to small unipolar lesions measuring less than 2-3 cm², whereas cartilage defects greater than 2-3 cm² are treated with either autologous chondrocyte implantation or
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260 Table 1 Recent Selected Studies on Outcomes Following Medial Opening-Wedge Proximal Tibial Osteotomy Number of Subjects
Mean Follow-up in Years (Range)
Average Age (Range)
Koshino et al27 Kolb et al28 DeMeo et al29
21
6.6
66.6
49 20
4.3 8.3
49 49.4 (36-67)
Haviv et al30
22
6.3 (⫾2.3)
44 (⫾13.7)
Hooper et al31 Bonasia et al32
36
Minimum 4 y
45 (21-57)
99
4.3 (⫾2.0)
54.5 (⫾9.2)
Saito et al33
78
6.5 (5-10)
68 (49-82)
References
Outcomes Improvement of American Knee score at followup ¼ 34.1 points Survivorship ¼ 92% Survivorship ¼ 70% Improvement of Lysholm score at follow-up ¼ 28.8 points Improvement of HSS Knee score at follow-up ¼ 10.9 points Survivorship ¼ 91% Improvement of Oxford Knee score at follow-up ¼ 14.8 points Survivorship ¼ 69% Survivorship at 5 y ¼ 99% Survivorship at 7.5 y ¼ 76% Improvement of Knee Society score at followup ¼ 24.9 points Improvement of WOMAC score at follow-up ¼ 25.4 points Improvement of Knee Society score at followup ¼ 38.5 points
HSS, Hospital for Special Surgery; WOMAC, Western Ontario and McMaster Universities Arthritis Index.
osteochondral allograft.43 Owing to the poor results in cartilage resurfacing procedures performed in “kissing” lesions involving corresponding femoral and tibial surfaces, osteotomy alone is preferred for this population of patients with bipolar chondral defects. Although most authors recognize the importance of unloading the affected compartment during cartilage resurfacing procedures,9 there is a relative scarcity of controlled studies to support this claim. Most of the available data on cartilage restoration procedures combined with osteotomy are buried in data sets evaluating the outcomes of those undergoing the cartilage procedure. A recent study by Bode et al44 was among the first studies to evaluate the effects of osteotomy on the
success or failure of cartilage resurfacing. In this study, 43 subjects with cartilage defects of the medial femoral condyle and varus deformities less than 51 underwent autologous cartilage transplantation with or without high tibial osteotomy. Those who underwent a combined autologous chondrocyte transplantation and high tibial osteotomy experienced better clinical outcomes and had a significantly reduced rate of reintervention (10.5% vs 41.7%) than those who had isolated autologous chondrocyte implantation.44 A recent systemic review attempted to determine the value of cartilage resurfacing in improving outcomes following osteotomy. A total of 4344 knees (57 studies) on which isolated high tibial osteotomy was performed were compared
Table 2 Recent Selected Studies on Outcomes Following Lateral Opening-Wedge Distal Femoral Osteotomy Number of Knees
Mean Follow-up in Years (Range)
Average Age (Range)
Das et al
12
6.2 (4.3-7.4)
55 (46-71)
Zarrouk et al35
22
4.5
53 (27-66)
References 34
Thein et al36
7
6.5 (⫾1.5)
46.7 (⫾10.7)
Dewilde et al37
19
5.7 (2.6-10.6)
47 (30-51)
Saithna et al38
21
4.5 (1.6-9.2)
41 (28-58)
IKDC, International Knee Documentation Committee.
Outcomes Survivorship ¼ 83.3% Improvement of HSS score at follow-up ¼ 14 points Survivorship at 8 y ¼ 91% Improvement in International Knee Society score at follow-up ¼ 25 points Survivorship ¼ 100% Improvement of Oxford Knee score at follow-up ¼ 12.9 points Survivorship at 7 y ¼ 82% Improvement of International Knee Society Knee score at follow-up ¼ 35 points Survivorship at 5 y ¼ 79% Improvement of IKDC score at follow-up ¼ 16.2 points Improvement of Lysholm score at follow-up ¼ 5.5 points
Osteotomy in cartilage resurfacing procedures
261
Table 3 Studies on Outcomes Following Combined High Tibial Osteotomy and Cartilage Resurfacing Procedure Number Resurfacing Technique References of Knees 40
Mean Follow-up in Years (Range)
Average Age (Range)
Microfracture
Sterett et al
106
6.8 (1.6-9.7)
52 (30-71)
Matrix-induced autologous chondrocyte implantation
Bauer et al41
18
5
47 (34-58)
Osteochondral autologous transfer
Minzlaff et al42
74
7.5
38 (19-62)
Outcomes Survivorship at 5 y ¼ 97% Survivorship at 7 y ¼ 91% Improvement of Lysholm score at follow-up ¼ 8 points Survivorship at 5 y ¼ 88% Improvement in KOOS pain score at follow-up ¼ 25 points Improvement in KOOS symptoms score at follow-up ¼ 10 points Survivorship at 7 y ¼ 93% Survivorship at 8.5 y ¼ 90% Improvement in Lysholm score at follow-up ¼ 33 points
KOOS, Knee Injury and Osteoarthritis Outcome Score.
with 399 knees (9 studies) on which high tibial osteotomy plus articular cartilage surgery was performed based on survival and clinical and radiographic outcomes.45 Although methodological variation in outcome score and length of follow-up among selected studies precluded meaningful evaluation of functional outcome, those undergoing a cartilage procedure in addition to high tibial osteotomy had a significantly higher 5-year survival rate (97.7% vs 92.4%) than those who had isolated high tibial osteotomy.45 However, both groups demonstrated deterioration of clinical outcomes with time (up to 10 years follow-up).45 Although limited, the current available literature supports the use of concomitant unloading osteotomy in improving the success rates of cartilage resurfacing procedures. Shifting the weight-bearing axis away from the overloaded compartment appears to improve the biomechanical milieu and thus increase the longevity of the cartilage resurfacing procedure. Failure to correct may expose cartilage graft or reparative tissue to excessive forces and premature failure. Therefore, any patient contemplating a cartilage resurfacing procedure should be evaluated for malalignment and, if present, an adjunctive unloading osteotomy should be considered.
Complications Knee osteotomies are demanding procedures that require meticulous surgical technique to avoid serious perioperative complications. Complications can be divided into perioperative complications, such as on neurovascular injury and fracture extending intra-articularly or through the far cortex (lateral cortex during a high tibial, opening-wedge osteotomy and medial cortex during distal femoral, opening-wedge osteotomy) during the osteotomy, and long-term complications that include nonunion, loss of correction, patella baja, arthrofibrosis, and prominent hardware. The rates of many long-term complications have decreased over recent years because of advances in fixation hardware and early postoperative range of motion.
Among the intraoperative complications, popliteal artery transection is a relatively rare, but potentially limb-threatening, injury described during knee osteotomy. During high tibial osteotomy, the popliteal artery is located 13-14 mm behind the posterior tibial cortex roughly 35 mm lateral to the posteromedial starting point of the osteotomy.46 Therefore, during creation of the osteotomy, a retractor should be inserted along the posterior tibial cortex and must traverse at least the medial 4 cm of the posterior tibia to provide adequate protection of the popliteal artery. Extension of the osteotomy intra-articularly or through the far cortex can result in articular surface incongruity or instability and subsequent nonunion of the osteotomy, respectively. Both entities must be recognized and addressed intraoperatively with appropriate fixation to limit potential disability. Risk of fracture propagation intra-articularly during high tibial osteotomy can be minimized by carrying the apex of the osteotomy within 1 cm of the lateral cortex and 1.5 cm from the lateral joint line.1 To prevent fracture of the far cortex, gradual opening of the osteotomy has been advised to allow for stress relaxation of the intact far cortex.1 Despite increased surgical times, complications rates of combining realignment procedures with other cartilage restoration procedures are not higher than those obtained with performing osteotomy alone.47 In a study analyzing complications in a cohort of patients undergoing combined osteotomy and reconstructive procedure, complications occurred in 37%, including 20% rate of major complications.47
Future of Technique The indications for realignment osteotomies will continue to be redefined as the technology of knee arthroplasty and cartilage restoration procedures evolves and the outcomes improve. With improvements in the durability of bearing surfaces and longevity of total knee arthroplasty, the need for isolated realignment osteotomies that have a limited lifespan will likely diminish. Technological advances in cartilage resurfacing
262 procedures may eventually allow for more durable repairs and therefore increase the indications for cartilage restoration. Consequently, osteotomies that unload the repair will continue to be a popular adjunct to improve the outcomes of these procedures. Advances in technology may result in less invasive, safer osteotomies that provide more precise corrections. Instrumented systems, such as the iBalance (Arthrex, Naples, FL), provide instrumentation that theoretically limits dissection, provides protection of the neurovascular bundle posterior, and assists in the creation of accurate cuts.48 Limited data are currently available on the outcomes following osteotomies using these systems.
Rehabilitation Protocol The goals of early rehabilitation are restoration of range of motion and minimizing quadriceps atrophy through isometric exercises. During the hospital stay, a continuous passive motion machine is applied to maximize passive range of motion. Once discharged, patients are instructed on passive motion exercises accomplished by placing the operative extremity off the side of the bed with the unaffected leg directly beneath for support. Patients are limited to toe-touch weight-bearing with a hinged knee brace and crutches for a minimum of 6-8 weeks. If healing of the osteotomy and maintenance of the correction is confirmed on radiographs, gradual advancement to full weight-bearing by 8-10 weeks is permitted. Formal physical therapy is generally initiated at 6 weeks postoperatively.
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