Proximal Femoral Osteotomies in Adults for Secondary Osteoarthritis: Femoral Osteotomies for Adult Deformity

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CHAPTER 32 Proximal Femoral Osteotomies in Adults for Secondary Osteoarthritis

Femoral Osteotomies for Adult Deformity

Daniël Haverkamp, Michel P.J. v/d Bekerom, René K. Marti

Introduction

Many orthopedic surgeons consider intertrochanteric osteotomy a historic operation with no role to play in modern clinical practice. This is true for a number of hip conditions, such as idiopathic osteoarthritis, rheumatoid arthritis, and severe osteoarthritis in the elderly patient. However, there exist conditions in selected younger patients with which an intertrochanteric osteotomy can produce excellent and long-lasting results. For these conditions, an intertrochanteric osteotomy should be the preferred treatment.

Historically, the first surgical treatment for osteoarthritis was a resection of the femoral head as described by Girdlestone. This was a pure salvage procedure, and its main aim was to reduce pain. The techniques of tenotomies described by Voss and the earliest intertrochanteric osteotomies by McMurray may also be regarded as salvage procedures. During the development of hip surgery, the goal of treatment gradually changed. Apart from pain relief, improving function and quality of life became increasingly important. When total hip arthroplasty (THA) became feasible, the goal of joint-saving therapy changed from mere salvage to palliation. We define an osteotomy as palliative when osteoarthritic changes are too advanced to save the joint but when a replacement can successfully be delayed with the use of this procedure. In the meantime, the osteotomy may even facilitate a future total hip replacement by improving the bone stock. Former salvage types of surgeries have no further role to play in the treatment of hip disorders, because these have been superseded by THA. Müller and colleagues advanced joint-saving hip surgery by describing and defining the role of intertrochanteric osteotomies in more detail. In addition, they introduced a therapeutic type of osteotomy that can be performed if osteoarthritic changes are not too advanced and if the cause of these changes is a biomechanical factor that can be corrected. If a biomechanical factor such as impingement, a dislocating force (e.g., stress on the labrum), or a small weight-bearing area is present, an early correction of this factor can biomechanically normalize the hip joint, which could lead to the long-lasting preservation of the joint. The differentiation between palliative and therapeutic intertrochanteric osteotomies is important in clinical practice. It is evident that therapeutic osteotomies should have a place in modern clinical practice. However, this is different for palliative osteotomies for younger patients with secondary osteoarthritis. Several studies show that the survival rates for salvage osteotomies among younger patients are approximately 70% to 80% after 10 years. The disadvantage of this type of osteotomy is that the results are mostly unpredictable. We believe that palliative osteotomy for younger and well-motivated patients should be considered and that the advantages and disadvantages should be discussed with these patients.

Indications

In the modern treatment regimens for severe osteoarthritis of the hip, THA is the treatment of choice for the elderly patient. During the past several decades, the age limit for this procedure has gradually been adjusted downward. Even so, the question remains regarding whether a THA is the best treatment for a young patient with mild (secondary) osteoarthritis. For patients with idiopathic osteoarthritis or rheumatic arthritis, no benefit from joint-saving surgery can be expected. However, for the treatment of the following indications, intertrochanteric osteotomies can provide good and long-lasting results:

• Coxa valga (antetorta)

• Mild dysplasia

• After slipped capital femoral epiphysis (SCFE)

• After Legg-Calvé-Perthes disease

• Posttraumatic deformities

Another somewhat controversial indication is avascular necrosis (AVN) of the femoral head. An intertrochanteric osteotomy that turns the necrotic defect away from the weight-bearing surface could prove to be useful and can be tried. However, the progression of the AVN and the subsequent collapse of the femoral head are unpredictable and still occur in a large portion of the patients after the osteotomy. The transtrochanteric rotational osteotomy described by Sugioka is, according to the literature, not reproducible by other orthopedic surgeons and therefore unsuitable for general practice. For osteoarthritis with femoral head deformities that presents after AVN when the AVN and the remodeling took place at a younger age, incongruence between the femoral head and the acetabulum can be present. An intertrochanteric valgus osteotomy improves the congruency, but subluxation of the femoral head occurs. In addition, an acetabular shelf plasty can successfully provide coverage for the severely deformed part of the femoral head. For AVN when remodeling is not yet complete, the deformed part of the femoral head that is turned from the acetabulum is covered by the bone graft, so it has the possibility of remodeling against the support provided by the graft.

Brief history and physical examination

It is normal practice to delay surgical interventions for elderly patients until complaints of pain or functional limitations are more severe and until more advanced osteoarthritic changes have occurred. To achieve optimal results, it is important to perform surgery as early as possible in patients who are suitable for intertrochanteric osteotomies, preferably after the first typical manifestation of the hip disorder.

Complaints among patients who are suitable for intertrochanteric osteotomy are not completely identical to those of older patients. In the latter case, complaints tend to occur after the cartilage has been destroyed to a large degree. Among patients who are suitable for intertrochanteric osteotomies, complaints are mostly caused by a factor such as incongruency, impingement, or stress on the acetabular labrum as a result of dysplasia. When screening these patients, the apprehension test (i.e., extension and external rotation) and the impingement test (i.e., flexion, adduction, and internal rotation) could play a role in detecting labral pathology at an early stage.

Every patient who is considered for an intertrochanteric osteotomy should be screened for suitability for the procedure and provided with information regarding the postoperative period. It should be explained to the patient that the osteotomy postpones the need for THA but does not eliminate it in all cases. Furthermore, the rehabilitation process should be explained, and the patient’s motivation should be evaluated. The outcome of an osteotomy is thought to be better among well-motivated patients.

Range of motion is an important part of the preoperative screening, because it demonstrates the amount of correction that is possible without jeopardizing hip function. Clinical investigation also reveals the limitations of movement and contractures. Contractures are especially important, because they can influence the correction required when performing the osteotomy. For example, in cases of an extension deficit (flexion contracture), extension can be added to the osteotomy. The same principle is valid for external and internal rotation contractures. Often it is not the functional limitation of the hip that bothers the patient but rather the painful overload of the neighboring joints.

Imaging and diagnostic studies

Functional x-rays can play an important role in the decision regarding the preferred intervention. An abduction view provides a radiologic impression of the amount of containment and the congruency that can be obtained by a varus osteotomy. An adduction and flexion x-ray does the same for a valgus or extension osteotomy. For patients with a coxa valga or mild dysplasia, it is important to make a clinical judgment regarding the amount of femoral torsion that is present. If an increased antetorsion is anticipated, then this should be verified by means of a Dunn x-ray or a computed tomography scan. In modern practice, the latter is more appropriate. For patients with suspected labral pathology, this can be verified with magnetic resonance arthrography.

Surgical technique

Because the surgical technique and preoperative planning differ in accordance with the indication, we will discuss the standard surgical technique followed by specific additions to the basic technique, all with their specific pitfalls and considerations. In the last paragraphs, we will describe the specific considerations for each indication.

Surgical Technique for Intertrochanteric Osteotomy

A standard lateral approach is used for all intertrochanteric osteotomies. The vastus lateralis is exposed by incising the fascia lata and reflected with Hohmann retractors to visualize the lateral femur (Figure 32-1, A). The vastus lateralis is sharply removed in the avascular plane from the vastus ridge. The vastus lateralis is detached from the intermuscular septum by blunt dissection, which allows for a wide inspection of the upper femur. Several perforating branches of the profunda femoral artery traverse the vastus lateralis and should be ligated correctly to avoid a postoperative hematoma; care should be taken so that the blunt dissection does not damage these vessels (see Figure 32-1, B). If it is necessary to inspect the hip joint, the approach can be extended proximally (i.e., the Watson-Jones approach), and the joint capsule can be opened to inspect the joint. The joint capsule is not routinely opened but rather only opened when indicated (e.g., for hump resection in a post-SCFE deformity). The linea aspera is decorticated. The seating chisel is inserted in the correct position, and the rotation is marked by placing a K-wire on each side of the planned osteotomy. Before this osteotomy is made, the seating chisel should be pulled back approximately 1 cm. An osteotomy parallel to the seating chisel is then made just proximal to the lesser trochanter (see Figure 32-1, C). Depending on the desired correction, a full or half wedge is removed to allow for the calculated varus–valgus or flexion–extension correction. During the osteotomy, blunt Hohmann retractors are placed around the femur to protect the femoral vessels and the femoral nerve. The definitive fixation is performed under compression with the classic AO (arbeitsgemeinschaft fur osteosynthesefragen) 90-degree or 100-degree blade plate, with different offsets that range from 10 mm to 20 mm. For cases in which extreme valgization is needed (e.g., for the treatment of femoral neck nonunions), a double-angled 120-degree or 130-degree blade plate can be used. For specific cases (e.g., intertrochanteric lengthening), a condylar plate is the preferred option. For all of our intertrochanteric osteotomies that involve the use of more or less right-angled blade plates, we performed the fixation under compression with the use of the AO compression device (see Figure 32-1, D and E). With the use of lateral compression, even open-wedge osteotomies heal without problems.

Figure 32–1 Preoperative pictures that illustrate the surgical technique of a classic intertrochanteric osteotomy. A, A standard lateral approach with an exposed vastus lateralis. B, Perforating branch of the profunda femoral artery is visible. C, After inserting the seating chisel and marking the rotation, a transverse osteotomy is made. D, Compression of the osteotomy with an AO compression device. E, After compression final fixation of the blade plate is performed.

Potential Pitfalls and Considerations for Intertrochanteric Osteotomy

Most of the described complications of intertrochanteric osteotomies can be avoided with the use of a good surgical technique. The incidence of a delayed union or nonunion can be greatly reduced with the proper use of an AO compression device. The anatomy of the intertrochanteric region is ideal for osteotomies, because the shape of this region allows for corrections in all planes while leaving large contact areas. Another advantage is the relatively good healing capacity of the metaphyseal bone.

In addition, the placement of the seating chisel or blade plate can cause problems. The occurrence of AVN caused by the osteotomy is a worry. The vascular supply of the femoral head is provided by branches of the dorsal circumflex artery, which can be damaged in the intertrochanteric fossa if the femoral neck is perforated by the seating chisel. This can be avoided with the correct placement of the seating chisel (Figure 32-2).

Figure 32–2 A, Schematic drawing of the vascular and surgical anatomy of the proximal femur. B, Surgical anatomy of the proximal femur with proper blade placement.

When flexion or extension is added to the osteotomy, the position of the femur after the osteotomy should be anticipated when planning the placement of the blade plate. For example, a seating chisel that is inserted too far anteriorly cannot be fixed properly to the femur after a flexion osteotomy (Figure 32-3).

Figure 32–3 Schematic drawing of the possible faulty placement of a blade plate in an flexion osteotomy.

Especially after a varus osteotomy, a long-lasting Trendelenburg gait can occur as a result of the relaxation of the gluteal muscles caused by the created femoral shortening. A good varisation should show a situation in which the tip of the major trochanter is not positioned higher than the center of the femoral head. If the center of the femoral head is positioned lower than the level of the tip of the major trochanter, the Trendelenburg gait could be permanent. If it is necessary to perform so much varisation that this occurs, a distalization of the major trochanter should be considered.

Surgical Technique for Shelf Plasty

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