|Year : 2021 | Volume
| Issue : 2 | Page : 83-87
Are different high tibial osteotomies needed for differing location and severity of deformities?
International Deformity and Lengthening Inst, Chaudhary Hospital, Akola, India
|Date of Submission||12-Dec-2021|
|Date of Decision||22-Dec-2021|
|Date of Acceptance||24-Dec-2021|
|Date of Web Publication||30-Dec-2021|
M.S. Orth Milind Chaudhary
International Deformity and Lengthening Inst, Chaudhary Hospital, Akola
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Chaudhary M. Are different high tibial osteotomies needed for differing location and severity of deformities?. J Limb Lengthen Reconstr 2021;7:83-7
Osteotomy surgery for medial compartment osteoarthritis (MCOA) of the knee was conventionally chosen based on familiarity with technique and hardware. Extended popularity of a single type of high tibial osteotomy (HTO) for long periods was the norm. Paley created an algorithm for bespoke correction of deformities in MCOA of the knee in 2009. This Editorial updates the algorithm by further classifying deformities and discussing the role of different HTOs in the current scenario.
Jackson and Waugh's seminal paper is most often cited for the closing wedge, though they described more than eight different types of upper tibial osteotomies. Simple instrumentation and early healing made the “Coventry Osteotomy,” popular for many decades. Its shortcomings and limitations gradually reduced its popularity. After 8 years, Coventry himself reported 60% survival and recurrence of varus deformity in many.
Koshino et al. solved many problems of the closing wedge by designing a barrel plate. They added a retinacular release to tackle patellofemoral pain and resection of osteophytes, which enabled an increase in range of motion to enable floor sitting, essential in many cultures.
The francophone world extensively practiced the medial open wedge osteotomy since the 1950s. Poignard et al. described more than 4000 cases over 50 years of the medial open wedge osteotomy.
Hemicallotasis or the gradual correction of a varus deformity by an opening wedge using an external fixator originated in Italy and spread globally. The minimally invasive percutaneous surgery and low-profile fixator made it surgeon and patient-friendly. The gradual correction permitted fine-tuning of alignment to the desired extent. However, the monoplanar fixator possibly reduced control in the sagittal plane. Faulty positioning of the proximal pins of the fixator could result in either procurvatum or recurvatum. External fixators may not be well tolerated by older patients.
Swiss–German–Japanese surgeons created the TomoFix locking plate system in the early years of the twenty-first century. The stable fixation permitted early and almost full weight-bearing walking. The titanium-niobium alloy plate had elasticity to permit micromotion which allowed the bone to form without grafting. Popularity of the medial open wedge surged due to accurate instrumentation, relative ease of the single cut osteotomy, and increased patient comfort. Enthusiastic followers pushed its indications and used it for correcting mild, moderate, and severe varus deformities. Despite early successes, limits and hidden complications have slowly emerged. Opening a large wedge created hinge fractures, instability, and delayed healing. Large corrections cause tilting of the knee and ankle joint line orientation. Inadvertent increase of the tibial slope occurs if care is not taken to distract more posteriorly. Ogawa et al. found overcorrection of Medial Proximal tibial Angle (MPTA) beyond 95° stressed the anterior cruciate ligament and patellofemoral joint cartilage. Despite its many advantages, it may not be ideally suited to correct deformities in all locations and of all magnitudes.
Maquet popularized the dome osteotomy, proximal to the tibial tuberosity to correct large deformities and allow early healing. However, the supratuberosity dome does not leave much space proximally for secure fixation. The proximal end of the distal fragment displaces medially, which reduces the lateral translation of the mechanical axis brought about by the valgus correction. This effect happens because the center of rotation of the dome is below the tuberosity.
A theoretically correct and practically useful dome was described by Paley, called the focal dome osteotomy (FDO). The dome was created around the center of rotation of angulation, just below the knee joint. The dome is convex distally, and its medial and lateral edges rise above the tibial tuberosity. Hence, when the distal fragment is brought into valgus, there is a mild translation of the distal fragment laterally. This lateral translation shifts the mechanical axis laterally and is more effective in unloading the medial compartment. The distal fragment can be externally rotated to add to the lateral translation of the mechanical axis at the knee [Figure 1]a, [Figure 1]b, [Figure 1]c.
|Figure 1: (a-c) Large varus deformity with internal rotation and shortening of affected limb. The TSF fixator used in lieu of the Ilizarov to perform a focal dome osteotomy which permitted correction of the varus, internal rotation and length as well. Notice the mild lateral translation of distal fragment|
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The osteotomy is distal and has enough space for fixation with a locking plate or an Ilizarov external fixator. The disadvantage of fixing it with a plate is that a finite end point to gauge correction may not be possible. Such a finite end point is possible to achieve with the opening and closing wedges, using the Dugdale and Miniaci method. Temporary fixation with wires or an external fixator is required to hold the correction till the plate is applied. However, evaluating correction on the table is fraught with error. Confounding factors include pelvic tilt due to a sandbag under the trochanter, internal rotation of the limb, thickness of the tourniquet, mild flexion at the knee, and rotation of the heel.
Using the hybrid Ilizarov fixator to fix the FDO mitigates some of the above disadvantages. The alignment can be modified till both targets are achieved: the first is the alignment of the mechanical axis to near the “Fujisawa point” at 62% of the knee joint width. The second is achieving valgus till the dynamic varus is eliminated. The latter frequently leads to overcorrection of the mechanical axis and may also tilt the knee and ankle joint line into the valgus. Some patients tolerate the overcorrection, but those without dynamic varus may not. The small lateral translation of the distal fragment reduces the valgus angulation at the ankle joint.
The chief benefit of the Ilizarov fixator is the ability to correct a large varus deformity without losing bony contact. The fixator gives sustained compression to achieve early and reliable union. Since the osteotomy is below the tuberosity, it does not affect the patellofemoral joint and cartilage. Any pre-existing patellofemoral pain can be addressed by adding a retinacular release. It is possible to combine correction of procurvatum or recurvatum deformities with treatment of chronic cruciate ligament injuries. The tibial slope can be reduced for chronic anterior cruciate and increased for posterior cruciate deficits.
Often, the varus deformity is accompanied by internal rotation or shortening of the limb. The internal rotation is easy to correct acutely on the table or gradually, along with lengthening. Hence, the Ilizarov fixator can correct a considerable primary varus deformity and the less recognized “Tertiary” deformities in the sagittal, axial, and rotational planes. The phenomenon of long-leg arthritis is well recognized. A high tibial valgizing osteotomy of the long leg will make it longer. Hence, the HTO can be combined with the shortening of the affected limb to achieve both aims.
The FDO does not cause either lengthening like an open wedge osteotomy or a shortening as in the closing wedge osteotomy. Finally, it can be performed simultaneously bilaterally, especially useful in young people. The FDO is thus ideally used for large varus corrections when accompanied by sagittal, axial, or rotational deformities.
Babis et al. proposed a double osteotomy of the lower femur and upper tibia for a large varus to reduce tilting of the knee joint line. These osteotomies require smaller wedges, a closing wedge laterally in the lower femur, and an opening wedge in the upper tibia. Nakayama et al. advised staging the osteotomies to achieve accuracy and in older patients who may not tolerate both osteotomies in the same surgery. The double osteotomy levies double the economic and physiologic cost on the patient and, when performed in stages, double the duration. Hence, it is ideally reserved for correction of large varus deformities in the young and active patients.
All the above are extra-articular osteotomies and, combined with reliable hardware, give excellent correction of the deformity. However, missing in this equation is the deformity arising from within the knee joint.
Many large varus deformities with a deviation of mechanical axis medial to the knee joint have an increased joint line convergence angle (JLCA). The increased angle denotes a lateral separation of the knee joint articulation and indirectly points to an intra-articular deformity. On clinical examination, large varus deformities may be associated with a dynamic varus gait and excessive mediolateral laxity. The laxity is a clinical sign of an intra-articular deformity. G. Chiba described an intra-articular upper tibial osteotomy called the tibial condylar valgus osteotomy (TCVO) as early as 1989. However, there are few reports of this in the English literature., This medial tibial condylar elevation osteotomy is similar to the hemi-plateau elevation performed for Blount's disease. The medial tibial plateau depression (MTPD) measures the lack of collinearity of the tibial condyles. It is large in Blount's and does not matter how it is calculated as errors in measurement will form a small percentage. The similar angle described for the intra-articular deformity in MCOA is the condylar plateau angle (CPA). A tibia with a large CPA is called a “Pagoda Tibia.” These patients do well after intra-articular osteotomy. The other two types described by Higuchi et al. are the “flat” type and the “depression” type. The flat one is unlikely to benefit from this surgery, and the depression type would be a contra-indication.
TCVO is performed as an L-shaped osteotomy with its vertical limb medial to the patellar ligament and its horizontal limb exiting medially, distal to the insertion of the superficial medial collateral ligament. A gentle valgus force achieves correction. An arthrodesis spreader allows more opening at osteotomy to achieve better correction of mechanical axis. Stopper wires are inserted medially and laterally to prevent the condyles from separating at the joint line. Once the adequate correction is achieved, the osteotomy is fixed with a medial locking plate [Figure 2]a and [Figure 2]b. Moderate varus deformities with an intra-articular component are best addressed with the TCVO. However, the mechanical axis may not reach the center of the knee or beyond. Despite undercorrection of the mechanical axis, the pain relief offered by this osteotomy is surprisingly good. “ “ Perhaps improved alignment is not the only reason for pain relief. High JLCA and CPA denote that the medial and lateral tibial condyles make alternate bony contact. Point loading of the medial condyles leads to cartilage overloading and pain. By elevating the medial tibial condyle, both medial and lateral condyles of the femur and tibia make simultaneous contact, increasing the weight-bearing area and reducing the cartilage loading.
|Figure 2: (a and b) Moderate varus deformity with a mild pagoda tibia and intra-articular deformity. Corrected with a tibial condylar valgus osteotomy with a plate. Postoperatively, mechanical axis comes near medial tibial spine, short of 50% of joint width|
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Undercorrection of the mechanical axis in TCVO gives cause for worry, and efforts have been made to improve correction of the mechanical axis beyond the center of the knee. Improving correction is possible by adding an extra-articular osteotomy, either as a closing wedge or a dome osteotomy distally.
Varus and valgus stress X-rays allow us to calculate the need for a second extra-articular osteotomy. We measure the opening angle on varus stress x-ray as positive and on valgus stress x-ray as negative. Both are added and multiplied by 1.5 to give angle β. A double osteotomy is needed if the angle α to correct the mechanical axis is greater than β.
The second osteotomy may be fixed in the same plate, after the L-shaped intra-articular one is fixed with a screw. An open wedge can be added through the same medial opening of the intra-articular osteotomy. The osteotome is angled laterally and toward the superior tibiofibular joint.
The second option is to add a closing wedge osteotomy an inch below the upper osteotomy and fix both of them with a locking plate.
The third is to perform a second osteotomy as a dome osteotomy an inch below the upper one and fix both with an Ilizarov fixator. [Figure 3]a, [Figure 3]b, [Figure 3]c Fine-tuning the distal osteotomy satisfactorily corrects the mechanical axis.
|Figure 3: (a-c) Large Varus deformity with an intra-articular component. Ilizarov fixator is used to fix the intra-articular as well as distal extra-articular dome osteotomy. Final result shows Opening wedge high tibial osteotomy = mechanical axis well corrected near the Fujisawa point. Patient was relatively young and could tolerate external fixator|
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While the TCVO may not correct Mechanical Axis Deviation (MAD) adequately, the addition of a second osteotomy with the Ilizarov has allowed correction to more than 50% of the joint width.
Given the inability of TCVO to correct MAD completely without a second extra-articular osteotomy, the question is can we combine an intra and extra-articular correction in a single osteotomy? Tsuchiya and Igarashi et al. have solved the problem with a new osteotomy called the focal dome condylar osteotomy (FDCO). This is an intra-articular osteotomy performed with its apex in line with the lateral tibial spine. is at approximately 60% of the knee joint width. Correction is possible beyond 50% or 60% of the joint width [Figure 4]a and [Figure 4]b. In contrast to the FDCO, the TCVO is medial to the patellar ligament, and its apex coincides with the medial tibial spine. Hence, the mechanical axis cannot cross 40%–45% of the joint width, which is the level of the medial tibial spine.
|Figure 4: (a and b) Large varus deformity with intra-articular component in a 65-year-old woman. Did not want an external fixator or a double osteotomy. The focal dome condylar osteotomy is performed to correct the mechanical axis to around 65% with a single osteotomy|
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These two intra-articular osteotomies relieve pain by improving bony contact between femoral and tibial condyles. The second mechanism is improved stability by stretching the cruciates. The osteotomy elevates the edges of the condyles. The intercondylar area comes down, and the distance from the roof of the notch to the intercondylar area is increased, tensioning the cruciate ligaments.
Hence, the author proposes an algorithm [Figure 5] to decide which osteotomy is ideally performed for which location and magnitude of deformity. The primary deformity is the varus. This may be mild, moderate, or severe. We classify the intra-articular deformity as a second or a secondary deformity. Clinical examination, gait and radiological analysis decide if it is present or absent. The tertiary deformity is not often looked for and may be present in the sagittal, axial, or rotational planes.
|Figure 5: Algorithm of choosing high tibial osteotomy based on location and severity of deformity. OWHTO: Opening wedge high tibial osteotomy, FDO: Focal dome osteotomy, TCVO: Tibial condylar valgus osteotomy, EAO: Extra-articular osteotomy. Note that focal dome condylar osteotomy can be used instead of TCVO when the varus deformity is large|
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A mild primary varus deformity, unaccompanied by intra-articular or sagittal/axial/rotational deformity may be corrected easily by a medial open wedge osteotomy or a lateral closing wedge and fixed with a locking plate. A mild-to-moderate primary varus with an intra-articular component can be best treated with a TCVO and fixed with a plate. A large varus deformity without an intra-articular component, with deformities in the sagittal/axial/rotational planes, can be treated by a dome osteotomy and fixed with either a locking plate or an Ilizarov external fixator.
A large varus deformity with an intra-articular component without sagittal/axial or rotational deformities can be treated with a FDCO. Finally, a large varus deformity accompanied by an intra-articular osteotomy and sagittal/axial/rotational deformities may be treated by a combination of TCVO and FDO.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]