Proximal Femoral Deformity

Key Points

Proximal femoral deformity may be iatrogenic or develop as a consequence of a pathologic process.
Treatment of proximal femoral deformity with total hip arthroplasty (THA) is challenging and requires careful preoperative planning.
The surgeon considering THA for proximal femoral deformity with previous surgery should have a high index of suspicion for infection.
Correction of the deformity is not always necessary.
Corrective osteotomy may need to be performed in a staged manner.
Outcomes of THA for proximal femoral osteotomy are generally comparable to those without deformity.

Total hip arthroplasty (THA) is among the most successful and cost-effective procedures in medicine, with excellent long-term outcomes, relatively low complications, and high patient satisfaction. Nevertheless, in certain circumstances, the procedure is more challenging and complex and is associated with less certain outcomes. Proximal femoral deformity increases the complexity of both primary THA and conversion hip arthroplasty.

The etiology of proximal femoral deformity is varied. Potential etiologies include prior proximal femoral osteotomy procedures, residual deformity after surgical or nonsurgical treatment of previous proximal femoral fractures, and bone deformity secondary to osteomalacia or metabolic bone diseases such as Paget disease or fibrous dysplasia.

In addition to the increased complexity that results from the location, direction, and degree of femoral deformity present, additional factors to consider for these patients include the potential for preexisting infection following the prior surgical procedures. In addition, prior osteotomy, fracture, or surgery may potentially compromise surrounding muscular, neurovascular or other soft tissue structures as well as bone strength or quality. To minimize downtime and return to function earlier, many patients would prefer to have the procedure performed in a single stage. However, in some complex cases, particularly when there is the possibility of joint or bone infection, a two-stage procedure may be preferable.

This chapter will review evaluation and classification of proximal femoral deformity in patients scheduled for primary or conversion THA, surgical treatment options and techniques, and the outcomes of surgical treatment.

Classification

Although proximal femoral deformity has been classified by several authors, the usefulness of a classification system is in its ability to guide treatment. The Berry classification describes femoral deformity based on the site of deformity, geometry of deformity, and etiology. Femoral deformity can occur at the level of the greater trochanter, femoral neck, metaphysis, or diaphysis. Additionally, at each level, the deformity can be further categorized as torsional (increased or decreased anteversion), angular (varus, valgus, flexion, or extension), translational (medial, lateral, anterior, or posterior), or an abnormality of size. These factors are often related, as particular etiologies create predictable deformities. Additionally, certain etiologies may affect bone metabolism, bone healing, or other systemic issues relevant to arthroplasty surgery. It is the location and geometry of the deformity that will ultimately dictate the choice of implant, its size, and any need for corrective osteotomy.

Surgical Treatment

Overview

A decision to proceed with primary or conversion THA in a patient with proximal femoral deformity begins with the clinical determination that the patient has sufficient pain and functional limitations related to the patient's hip disease to warrant the risks of surgery. Following a proper informed consent process, the patient should have an opportunity to make an informed choice that accepting the risks of proceeding with hip arthroplasty is preferable to nonoperative management or other surgical options.

During preoperative planning, in addition to the classification of the deformity, it is important to consider the etiology of the patient's proximal femoral deformity; location, direction, and magnitude of the deformity; surrounding bone quality; relevant muscle function; neurovascular status of the patient; the patient's health and functional potential; and the likelihood of associated joint or bone infection. These factors are important to determine the risks and probable benefits of hip arthroplasty as well as to prepare for the optimal approach, implant, and technique. From a technical standpoint, the acetabular surgical technique usually should not be altered owing to the presence of the femoral deformity. On the other hand, on the femoral side, strategies commonly involve use of shorter implants and staying short of the deformity or performing an osteotomy and bypassing the deformity. Most surgeons recommend bypassing the deformity by at least 2.5 shaft diameters.

Etiology

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