Patients with deformity of the proximal femur typically develop arthritis over time because of abnormal joint wear from malalignment. Deformities typically include a varus or valgus neck-shaft angle, rotational malalignments, and leg-length discrepancy in any combination. These deformities can be acquired, as in the case of proximal femur fracture malunions and nonunions, or developmental, as in the cases of fibrous dysplasia, coxa vara, and developmental dysplasia.
Regardless of the etiology, these patients with femoral deformity are at an increased risk for the development of pain and arthritis in the affected hip. Once arthritis has begun, the problem is further aggravated by the mechanical malalignment from the femoral deformity. Standard hip replacement techniques and prostheses are usually unsuitable for deformed proximal femora, thus increasing the complexity of the procedure, surgical risks, and possibly the longevity of the reconstructed joint.
Proximal femoral osteotomy was a technique used in adults in the early part of the 20th century for the treatment of hip dysplasia and osteoarthritis. Varus- and valgus-producing osteotomies were aimed at maximizing joint congruity and redistributing the weightbearing load across the femoral head to a less affected area. Historically, the best results were obtained in patients with long-standing deformities, including Perthes osteonecrosis, coxa vara, and developmental dysplasia.
Modern periacetabular osteotomies  and joint arthroplasty techniques have narrowed the indications for this once common procedure. Proximal femoral osteotomy continues to find application in adults for the treatment of hip fracture nonunions and malunions and in cases of congenital and acquired hip deformities. [2, 3]
The benefits of early proximal femoral osteotomy to correct the deformity are twofold. First, in the deformed hip prior to the onset of arthritic changes, the realignment often reduces symptoms and prevents further joint degeneration. In the deformed hip with arthritic changes, restoration of normal alignment can often decreases pain and improves function. Moreover, if the relief of symptoms is incomplete and the patient later requires hip replacement surgery, then the arthroplasty procedure is simplified by restoration of the anatomy.
In young patients with symptomatic hip disease, total joint arthroplasty has traditionally been a suboptimal solution. Problems with accelerated bearing wear and premature implant loosening leading to early revision surgery are well documented in this patient population. Intertrochanteric osteotomy has some use in providing temporary relief of pain in this challenging group of patients.  Whereas newer bearing materials with improved wear properties may improve the longevity of total joints in young patients, data to support this position are yet lacking.
The bases for performing a proximal femoral osteotomy can vary. In the presence of deformity, the goal is to correct the deformity and, in so doing, to realign the hip and lower extremity. This may include frontal, sagittal, and rotational corrections and perhaps even lengthening through the osteotomy.  Indications for proximal femoral osteotomy in adults include the following:
Nonunion of a femoral neck fracture
Nonunion or malunion of an intertrochanteric hip fracture deformity - This includes rotational deformities (eg, severe femoral anteversion, slipped capital femoral epiphysis [SCFE], and developmental dysplasia of the hip); frontal plane (varus/valgus) deformities (eg, congenital coxa vara, varus fracture malunion, and shepherd's crook deformity from fibrous dysplasia); sagittal deformities, including flexion and extension deformity, either bony (eg, fracture malunion) or nonbony (eg, hip flexion contracture of achondroplasia); and significant shortening or bone loss of the distal femur requiring a proximal lengthening
Combinations of the above indications, as in intertrochanteric fracture malunion with varus, external rotation, and shortening deformity
Simultaneous femoral osteotomy and total hip arthroplasty
Hip osteoarthritis or osteonecrosis in the young, active patient
Femoral neck nonunion
In femoral neck nonunion, the fracture fails to heal despite an adequate blood supply. Weightbearing forces across a vertically oriented fracture line produce shear stresses at the fracture site that favor the production of fibrous tissue. Valgus intertrochanteric osteotomy reorients the fracture site into a more horizontal position. Axial loading in this situation encourages osteogenesis and fracture union.  (See the images below.)
Intertrochanteric nonunion or malunion
Intertrochanteric hip fractures typically do not disturb the blood supply to the femoral head and tend to heal predictably. Nonunions of this common fracture pattern are usually the result of a combination of varus malalignment and inadequate stability of fixation. Treatment is aimed at correcting the varus neck-shaft angle to a neutral or slight valgus orientation and improving the stability at the fracture site, often with a fixed-angle device.  (See the images below.)
When the fracture collapses into varus angulation and then goes on to bony union, a malunion results. The hallmark of this malunion is a varus neck-shaft angle with shortening of the ipsilateral femur, shortening of the abductor musculature or lever arm, and often trochanteric-pelvic abutment and a Trendelenburg gait with poor hip motion. This patient is at an increased risk for the development of hip arthritis. Intertrochanteric osteotomy serves to realign the hip joint, restore normal abductor mechanics, and reestablish equal leg lengths.
SCFE is a common fracture variant seen in the adolescent population.  In many cases, in-situ pinning of the displaced fracture is indicated, because this reduces the risk of osteonecrosis of the femoral head. If a displaced slipped epiphysis heals in situ, a fracture malunion can result. After remodeling, this malunion is characterized by coxa vara, femoral shortening, and retroversion of the femoral neck with a significant loss of hip motion.
A valgus-producing proximal femoral osteotomy can correct the varus and reestablish normal rotation, both of which reorient the femoral head in the acetabulum, offering possible protection from the development of arthritis. This procedure also equalizes limb length and abductor tension, thereby normalizing gait.
A shepherd's crook deformity of the proximal femur has long been associated with fibrous dysplasia. Repeated microfractures of the femoral neck lead to progressive displacement and healing of the femur in varus. Significant shortening of the femur, trochanteric-pelvic abutment, and shortening of the abductor lever arm occur concomitantly. Rotational deformity may also be present. 
Patients report limb shortening, hip stiffness, and an inability to abduct the lower extremity, which can be particularly troublesome for women of childbearing age. Pain may be present as well. These patients are at risk for progression of the deformity, fracture of the femoral neck, and joint degeneration. Valgus-producing proximal femoral osteotomy serves to prevent progression of the deformity and the development of a fracture, reestablish a more normal femoral head–acetabular relationship, lengthen the extremity, tension the abductors, and greatly improve hip abduction.
Developmental dysplasia of hip
Adults with hip dysplasia often have both acetabular and femoral deformity. The femoral neck assumes a valgus and anteverted orientation, while the acetabulum is shallow with varying degrees of uncovering of the femoral head, ranging from mild to subluxed to a frank dislocation. In select patients, surgery is indicated to improve femoral head coverage or better reduce the hip joint. A varus-producing proximal femoral osteotomy with derotation of the anteverted neck improves femoral head orientation. Often, this is combined with a periacetabular osteotomy to improve superolateral and anterior head coverage. [9, 10, 11]
Osteoarthritis and osteonecrosis
The goal of the femoral osteotomy is to alter the contact point across the articular cartilage during weightbearing. When arthritic change occurs without deformity, then a valgus-extension osteotomy moves the contact point of weightbearing forces to a new location on the femoral head, alleviating the pressure across the degenerated area of articular cartilage. This area of damaged cartilage has been shown to undergo a reparative process through which new collagen is created. (See the images below.)
Contraindications for femoral osteotomy include the following:
The presence of infection may preclude the use of internal fixation; however, external fixation may be a viable option in such cases
Limitations of hip motion can make realignment unsuccessful without soft-tissue releases or compensation through the osteotomy
Advanced osteoarthritis or osteonecrosis is a relative contraindication
Inflammatory arthritis can also be a contraindication
Proximal femoral osteotomy is a joint-sparing procedure that relies on maintaining the biologic integrity of the femoral head. Preserving the blood supply to the femoral head is of the utmost importance. In adults, the medial femoral circumflex artery is the predominant nutrient vessel supplying the femoral head. Proximal femoral osteotomy is performed via a lateral approach, reducing the chance of injury to this vessel.
Other relevant anatomy includes knowledge of the normal anatomy of the femur. Normal neck-shaft angle is in the range of 124-136°. The center of the femoral head lies at a similar height as the tip of the greater trochanter. A line connecting these 2 points makes an angle of 90° (range 85-95°) with the mechanical axis of the femur.
When proximal femoral osteotomy is used for the correction of congenital and acquired deformities and repair of hip fracture nonunion, results have been favorable. Hip range of motion, gait, pain, leg-length discrepancy, and patient satisfaction are improved. If arthritis develops, then future joint replacement is often facilitated. Simultaneous femoral osteotomy and total hip arthroplasty is a technically demanding procedure that has yielded acceptable results for complex hip reconstruction with deformity.
With regard to the use of proximal femoral osteotomy in the nondeformed hip with osteoarthritis, long-term follow-up reveals that many patients go on to require total hip arthroplasty. Some authors conclude that a place still exists for osteotomy in the treatment of hip osteoarthritis in younger patients. However, many have reported on the increased difficulty and higher complication rates associated with total hip arthroplasty performed in hips that have undergone previous intertrochanteric osteotomy procedures aimed at alleviating arthritic pain.
Aydin et al studied the long-term clinical and radiographic results of femoral varus derotation osteotomy in a group of patients with the diagnosis of Legg-Calvé-Perthes disease.  A total of 21 hips were evaluated, and the mean duration of postoperative follow-up was 25.1 years. The main determinants of radiographic outcome were (1) age at the time of surgery and (2) preoperative lateral pillar classification, whereas those significantly correlated with progression to degenerative arthritis were (1) preoperative lateral pillar classification and (2) Stulberg group at maturity.