Lateral Release for Fixed Valgus Deformity

Frankie M. Griffin, Giles R. Scuderi, and John N. Insall

VALGUS DEFORMITY IN TOTAL KNEE ARTHROPLASTY

Fixed-valgus deformity of the arthritic knee can be a difficult and challenging problem in total knee arthroplasty. Varus deformity is more commonly encountered, and therefore most surgeons are more comfortable with the surgical principles and releases used on the medial side of the knee. At our institution, at the time of knee replacement we encounter fixed-varus deformity (50 to 55%) three times more frequently than fixed-valgus deformity (10 to 15%). Ligament balancing and changes in boney anatomy of the valgus knee may be more difficult to correct than with varus deformity. in addition, the correct sequence and technique of release of the lateral structures remain controversial. Many different techniques to correct valgus deformity have been described, and they demonstrate the lack of a consensus among surgeons. Potential complications—including peroneal nerve palsy, flexion or extension instability, and patellar maltracking—also make correction of valgus deformity challenging.

PATHOPHYSIOLOGY

The normal knee is aligned with a femorotibial angle of 6 to 7 degrees valgus, has a full range of motion, and may be slightly more lax laterally in flexion. in arthritis of the knee, loss of bone and cartilage leads to instability, which can be classified as either symmetric or asymmetric. in response to the instability, adaptive changes occur. in fixed-valgus deformity the instability is asymmetric, and the surgeon is faced with deficiency of the lateral bone and cartilage, contracture of the lateral ligaments and capsule, stretching of the medial ligaments, and contracture of the ilio-tibial tract. The structures that may be "tight" include the lateral capsule, lateral collateral ligament, arcuate ligament, popliteus tendon, lateral femoral periosteum, distal iliotibial band, and lateral intermuscular septum.1 In addition, there may be asymmetric wear of the posterior condyles with excessive wear of the posterolateral condyle. This wear has implications in surgical technique if the posterior condyles are utilized to reference femoral component rotational alignment.2 Some authors have also reported external rotation deformity of the proximal tibia due to the tight iliotibial tract.3

SURGICAL TECHNIQUES

Implant Selection

The successful results of total knee arthroplasty with the posterior-stabilized design are well documented in the literature.4 In severe deformity, the PCL is often contracted and may limit correction of the deformity as described by Krackow's "cruciate limitation effect."5 Even when an attempt at PCL-retention was made, Laurencian found that in 16% of knees he had to release the PCL.6 Appropriate soft tissue balancing is much easier if the PCL is sacrificed. We believe it is much simpler to substitute a mechanical PCL for the diseased and contracted PCL in the severely deformed knee and that the results for the average surgeon will be better when the PCL is sacrificed routinely than when an attempt is made at soft tissue balancing with partial releases of the PCL and use of a posterior cruciate-retaining prosthesis. We therefore recommend use of the posterior-stabilized design.

In elderly low-demand patients, we prefer to use a constrained condylar knee to avoid the morbidity of extensive releases on the lateral side of the knee and to avoid the potential complications of peroneal nerve palsy and instability in flexion or extension. Bullek and associates (1996) evaluated the results of index-constrained condylar total knee arthroplasty in 28 patients with 34 TKAs.7 The average age was 74.5 years, and the average preoperative deformity was 22 degrees valgus. No attempt at soft tissue balancing with lateral releases was made. Sixty-two percent required lateral retinacular releases for patellar tracking. All 34 TKAs (100%) had excellent (25 knees) or good (9 knees) results at an average follow-up of 3 years, and there was no evidence of early loosening or osteolysis. In younger patients, every attempt should be made to balance the knee and to avoid use of the constrained implant to eliminate the concern of early loosening in the more active, younger population.8

In some cases with bone deficiency, a modular implant with metal augments, offset stems, and variable tibial polyethelene thicknesses may be useful. In valgus deformity, patellar tracking is almost always an issue with lateral release rates reported from 62 to 100%.7,8 Though one may speculate that the use of an implant that provides both left- and right-sided femoral components may improve patellar tracking, proper patellar preparation, and correct femoral component rotation are critically important.

Bone Cuts

Our preference is the medial parapatellar approach for all cases. Lateral osteophytes are often present and should be removed. The significance of the lateral osteophytes is debatable because the LCL's insertion on the fibular head takes the ligament away from the tibial rim, and therefore, lateral osteophytes do not typically bowstring the LCL the way that the medial osteophytes often impinge on the MCL.9 However, Keblish and colleagues (1991) reported fewer LCL, popliteus, and capsule releases when the overhanging osteophytes were removed and a laminar spreader used to "tease" the joint apart in flexion and extension.10

Femoral component rotational aligment is important in the valgus knee to avoid flexion instability after lateral ligamentous release.1 The surgical epicondylar axis may be helpful for rotational alignment of the femoral component in the valgus knee (Fig. 4.1).11 Most current total knee instrumentation systems reference the rotation of the femoral cuts from the posterior condyles with some built-in "external rotation"—often around 3 degrees. However, in severe valgus deformity, the posterolateral condyle may be more worn, and therefore the amount of "external rotation" may need to be increased in reference to the posterior condyles. Because of the variability and posterolateral wear, the surgical epicondylar axis is a better reference for femoral component rotation than the posterior condyles—especially in valgus knees. In a recent study, we measured the posterior condylar angle (defined as the angle formed by the tangent to the posterior condyles and a line through the epi-condyles as depicted in Figure 4.1) in 107 consecutive TKAs in 88

Lateral Epicond] Prominence

Posterio Condyla Angle

Lateral Epicond] Prominence

Posterio Condyla Angle

Epicondylar Axis

Posterior Condylar Line

Medial Sulcus

Surgical Epicondylar Azis

FIGURE 4.1. Surgical epicondylar axis posterior condylar angle.

Posterior Condylar Line

Medial Sulcus

Surgical Epicondylar Azis

FIGURE 4.1. Surgical epicondylar axis posterior condylar angle.

osteoarthritic patients and found the posterior condylar angle to be 3.29 ± 1.93 degrees for varus knees, 3.25 ± 2.25 for knees with no deformity, and 5.37 ± 2.29 for valgus knees. This led us to note that the posterior condylar angle was significantly greater in valgus knees compared to the other deformities (p < 0.05). The large standard deviations denote the variability of the posterior condylar angle in these osteoarthritic patients, and demonstrate that for valgus knees the surgical epicondylar axis is a more anatomic and consistent landmark.

The medial and lateral epicondyles are readily identified during routine exposure of the knee joint. The medial epicondyle is a horseshoe-shaped ridge on the medial femoral condyle that serves as the femoral attachment of the superficial fibers of the medial collateral ligament.11 The center of the medial epicondyle is an indentation or sulcus where the deep fibers of the MCL insert (Figure 4.2).11 In those knees where a sulcus is easily palpable, the center of the sulcus is marked. In those knees where the sulcus is not easily palpable, the fan-shaped origin of the MCL is identified on the medial femoral condyle and outlined with a marker. This forms a semicircle, which is then completed into a full circle. The

Sulcus Femoris
Figure 4.2. Medial epicondylar sulcus.

center of the circle represents the sulcus and is the location of the medial epicondyle. The peak of the lateral epicondyle is more easily seen because it is the most prominent point on the lateral side. A line is drawn across the distal femur connecting those two points establishing the epicondylar axis.

The femoral component should be aligned with 5 to 7 degrees valgus angulation in the coronal plane and 0 to 10 degrees of flexion in the sagital plane.12 Whitesides (1993) noted that appropriate placement of the femoral component is important to obtain appropriate joint line position in relation to the patella and to avoid damage to ligament attachments. Often the distal lateral femoral condyle is deficient and sclerotic.3 Therefore, the distal femoral resection entails resection preferrably from the medial femoral condyle and little or no bone resection from the lateral femoral condyle. In cases of severe genu valgum, the lateral femoral condyle may need to be bone grafted3 or—as we prefer— built up with metal augmentation. By using this method of setting the distal femoral joint line, the joint line is not raised and ligament balancing in flexion and extension is achieved. This technique also helps to maintain the patellar height.

The tibial cut should be made at 90 ± 2 degrees to the long axis of the tibial shaft in both the coronal and sagital planes.12 White-sides has noted that over-resection of the proximal tibia to address a bony defect and create a flat surface for the tibial component may damage ligament attachments and may sacrifice excessive amounts of bone.3 We have seen routine resection transect the popliteus tendon or detach the iliotibial band from the proximal tibia at Gerdy's tubercle. So caution must be taken when resecting the proximal tibia. The medial tibia is referenced and 10 mm of bone is resected. Bony defects can be addressed with cement, bone, or metal augments. The MCL must be protected during resection.

Soft Tissue Releases

The purpose of our release is to provide ligamentous balance with rectangular flexion and extension gaps (Fig. 4.3) while maintaining lateral side stability of the knee in flexion. The structures to be released may include the iliotibial tract, arcuate ligament, LCL, popliteus, biceps femoris, lateral gastrocnemius, lateral patellar retinaculum, PCL, and others. The release can be a full release, partial release, or Z-lengthening. Multiple soft tissue procedures have been described for use with valgus deformity with each of these structures. 3,6,8-10,13-21 The order of release varies among sur-

Knee Flexion And Extension Gap
Figure 4.3. Flexion and extension gaps.

geons, and Table 4.1 shows the preferences of several surgeons as described in the literature.

Because access to the lateral supporting structures is easier, we prefer to perform the release after the tibial cut and distal femoral cut have been completed. Release is performed in a step-by-step controlled fashion and reassessed with laminar spreaders after each step. The endpoint of release is when the mechanical axis passes through the center of the knee and the flexion and extension gaps are equal and symmetrical.

our preferred method of release is to begin by transversely cutting the posterolateral structures (arcuate ligament, posterolat-eral capsule, and reinforcing ligaments) just below the popliteus tendon from the corner of the cut surface of the tibia. Because the lateral meniscus has been removed, the popliteus tendon can be readily identified and kept out of harm's way. When complete, the muscle belly of the popliteus and the lateral head of the gastroc-nemius may be seen posteriorly. Soft tissue balance is rechecked with laminar spreaders, and occasionally release of the posterolat-eral structures alone is adequate. Usually with a fixed-valgus deformity, further release is necessary, and a "piecrust" release of the iliotibial tract and LCL is performed with a 15 blade by making multiple horizontal incisions in the iliotibial tract under direct

TABLE 4.1. Sequences of release

Author

First step

Second step

Third step

Final steps

Ins all17 ,18

Posterolateral corner

Iliotibial tract

LCL, LIS

CCK

Ranawat21

Iliotibial tract

Popliteus, LCL

Posterior capsule

LIS, lateral head of gastrocnemius

transverse (2.5cm)

Keblish10

Lateral approach

Iliotibial tract multiple

Posterolateral corner

Gerdys tubercle, tibial tubercle

puncture

elevation

Buechel13

Lateral approach

Iliotibial tract

LCL, popliteus

Fibular head excision

Clayton14

LCL, popliteus, lateral

Posterolateral capsule,

Iliotibial tract

Biceps femoris tendon

capsule

lateral head

Z-lengthening

gastrocnemius, LIS

Whitesides3

Iliotibial tract

Popliteus

LCL

Lateral head of gastrocnemius

Krackow20

Iliotibial tract

Popliteus

Posterolateral capsule,

Biceps femoris tendon, lateral

popliteus

head of gastrocnemius,

MCL advancement in Type II

LIS = Lateral intermuscular septum LCL = Lateral collateral ligament CCK = Constrained condylar knee visualization from inside to out (Fig. 4.4). It is helpful to keep the laminar spreaders in place during this release and to periodically squeeze them to stretch the lateral side. This works like a tensor and allows the lateral tissues to lengthen and slide with some degree of continuity. The incisions begin at the level of the joint line and are usually taken to a level approximately 10 cm proximal to the joint line. The release is carried further proximally if necessary. By this stage, a "pop" is usually felt and the valgus deformity is adequately corrected. The popliteus tendon should be preserved if possible to provide lateral stability in flexion. In our hands, release of the ITB and posterolateral corner corrects the majority of fixedvalgus deformities. If further release is still necessary, we proceed with a subperiosteal release of the remaining lateral structures including the lateral intermuscular septum to a point 7 to 8 cm from the joint line so that the whole "flap" is free to slide (Fig. 4.5). By this stage, almost all cases will have balanced, but if in the rare case further release is needed, we would release the lateral head of the gastrocnemius from its femoral attachment. Release of the biceps femoris should be avoided if at all possible. If after complete release the medial ligament is too lax, then the ligament

Lateral Release
Figure 4.4. Piecrusting technique for valgus deformity.
Lateral Release
FIGURE 4.5. Lateral release from the distal femur for extreme valgus deformity.

reconstruction procedures described by Krackow5,20 should be considered, although we have limited experience with this option. Finally, if ligament stability cannot be achieved, a constrained condylar implant will be used.

Patellar maltracking is often associated with a valgus deformity. If present, a lateral retinacular release should be performed.

Postoperative Management

Patients who have undergone ligament releases for fixed-valgus deformity are managed in a manner similar to those who have had routine total knee arthroplasties. The knee is placed in a continuous passive motion (CPM) machine in the recovery room, because we have found CPM to decrease the rehabilitation period required to achieve 90 degrees of flexion.22 To avoid a postoperative flexion contracture, we recommend use of a knee immobilizer during sleep for patients who have a tendency to flex their knee while sleeping. On the second postoperative day, patients are instructed to stand with assistance, and by the third postoperative day, they resume walking with full weight-bearing with crutches or a walker. Goals for hospital discharge include independent ambulation with crutches or a cane, ability to climb stairs, and attainment of 90 degrees of flexion.

COMPLICATIONS

Peroneal Nerve Palsy

With release of the lateral structures and correction of valgus deformity, some stretching of the peroneal nerve is unavoidable and some degree of postoperative ischemia can be predicted with this stretching. Peroneal nerve palsy has been reported in 3% of patients who underwent TKA with preoperative valgus deformity.8 In addition to valgus deformity, risk factors that have been shown to increase the risk of peroneal nerve palsy include previous laminectomy and postoperative epidural anesthesia.22 Some authors have described dissection of the peroneal nerve from its fascial sheath behind the fibular head and even fibular head resection in an attempt to avoid this complication.10,13 However, a definitive benefit has not been shown and the possibility of direct injury is probably increased by the dissection. Therefore, we do not recommend direct exploration of the peroneal nerve. Idusuyi and associates (1996) reported that peroneal nerve palsy may present in a delayed fashion.22 Placing the knee in a CPM machine in the recovery room reduces the tension on the peroneal nerve by allowing early flexion and by avoiding prolonged extension of the knee. If a peroneal nerve palsy is noted in the early postoperative period, the treatment is one of observation because the natural history of a postoperative peroneal nerve palsy is gradual partial or complete recovery. Stern and colleagues (1991) followed five patients with postoperative peroneal nerve palsies and noted that all tended to resolve over time, although all were left with some residual neurologic deficit.8 Asp and Rand (1990) reported the natural history of 26 postoperative peroneal nerve palsies that occurred after 8998 TKAs.23 In this group, they found that 18 had complete palsies and 8 had incomplete palsies with 23 combined motor and sensory deficits and 3 with only motor deficits. At an average of 5.1 years after TKA, 13 had complete recovery, 12 had partial recovery, and 1 had no improvement. Partial palsies had a better prognosis for complete recovery and had higher knee scores than those with complete palsies. Those with complete recovery also had higher knee scores than those whose recovery was incomplete. Krackow and associates (1993) reported the results of operative exploration and decompression of the peroneal nerve in 5 patients who developed peroneal nerve palsycomplicating TKA.24 The procedure was performed 5 to 45 months after the index TKA, and the patients were graded pre- and postoperatively using a standard nerve palsy scale. They found that all 5 patients had improved nerve function and that 4 of the 5 patients had complete peroneal nerve recovery after the decompression. Thus, consideration should be given to surgical decompression of the peroneal nerve in cases that fail to respond to nonoperative measures.

Instability

Instability in extension can be described as either symmetric or asymmetric. Symmetric instability occurs when the extension gap is larger than the flexion gap resulting in residual laxity of the collateral ligaments in extension due to incomplete filling of the extension space by the prosthesis. Often this situation is caused by over-resection of the distal femur. Sometimes this problem can be solved by inserting a thicker tibial component. However, if the flexion gap is too tight to accommodate the thicker tibial component, the distal femur may need to be built up to make the extension gap smaller.9 Asymmetric instability often is associated with inadequate release of a tight ligament. Therefore, ligament release in the stepwise fashion described earlier can be used to correct tight lateral ligaments. If asymmetric instability persists or if further release may result in overlengthening of the limb, a constrained condylar prosthesis should be utilized.

Resection of an insufficient amount of bone from the distal femur may also lead to flexion instability by forcing the surgeon to use a thinner tibial component to accommodate the smaller extension space.9 Valgus release may also result in lateral instability in flexion. Preservation of the popliteus and a lengthened lateral soft tissue sleeve, when possible, may help to prevent this. In addition, use of the surgical epicondylar axis to rotationally orient the femoral component will ensure a more appropriate flexion gap based upon the patient's anatomy.

Patellar Instability

Lateral retinacular release is necessary in most severe valgus knees during total knee arthroplasty with surgeons reporting release rates of 62 to 100%.7,8 Appropriate rotational alignment of the femoral component based upon the epicondyles with the surgical epi-condylar axis or "external rotation" of the component—up to 5 or

6 degrees in relation to the posterior condyles—will improve patellar tracking. In addition the tibial component should be oriented by aligning the intercondylar eminence with the tibial crest. Proper rotational alignment of the components along with lateral retinac-ular release when necessary should diminish patellar complications. If the patella appears to be tracking laterally after lateral retinacular release, the rotational position of the components should be reevaluated, and if deemed correct, then a proximal patellar realignment should be performed during closure of the arthrotomy.

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Responses

  • gaudenzio
    What structures are cut in lateral release?
    6 years ago
  • Wilma
    Is a lateral release included in an arthroplasty?
    6 years ago
  • Lucy
    Is a knee immobilizer always recommended for patellar maltracking/lateral release?
    6 years ago
  • lucile banta
    Is knee immobilizer needed after lateral release?
    6 years ago
  • carmen
    What is valgus deformity turns into peroneal nerve palsy?
    6 years ago
  • samsa
    How important is soft tissue balance to knee function?
    5 years ago

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