Total hip arthroplasty (THA) is an effective treatment for advanced hip arthritis from a variety of causes, including osteoarthritis, inflammatory arthritis, posttraumatic arthritis, and sequelae of developmental disorders. It is not uncommon to perform THA in the presence of a previous proximal femoral osteotomy that may have been performed for slipped capital femoral epiphysis (SCFE), Legg-Calvé-Perthes disease, or developmental dysplasia of the hip, among other conditions. These osteotomies are commonly combined with internal fixation, a plate-and-screw device. These patients are at risk for developing degenerative arthritis at an earlier age than patients with other types of arthritis and subsequently may undergo THA at a younger age.1-3 Presence of a plate can pose a technical challenge during THA surgery. THA performed after intertrochanteric osteotomy has higher rates of perioperative and postoperative complications.4 Ferguson and colleagues4 noted difficulty during hardware removal in 24% of cases. Among the complications encountered were broken hardware, stripped screws, greater trochanteric fracture, stress risers from previous screw holes, canal narrowing from endosteal hypertrophy around hardware, and lateral cortical deficiency after removal of the side plate. As intertrochanteric osteotomies are often performed in patients who have yet to reach skeletal maturity, cortical hypertrophy can lead to complete coverage of the side plate and an “intracortical” position.
This article reports on 2 THA cases in which a technique was used to avoid intracortical plate removal and the resulting problems of lateral cortical deficiency. During each THA, the plate was left in place to avoid compromise of the lateral femoral cortex. The patients provided written informed consent for print and electronic publication of these case reports.
Case Reports
Case 1
An adolescent with bilateral SCFE was treated first with internal fixation of the right hip and subsequently with left proximal femoral osteotomy with internal fixation. He did well until age 31 years, when he developed progressively worsening pain about the left hip. Clinical findings and imaging studies were consistent with advanced degenerative arthritis of the left hip. Radiographs showed a sliding hip screw in place, with proximal femoral deformity consisting of femoral neck shortening and posterior angulation (Figures 1A, 1B). Preoperative Harris Hip Score was 54.5.
Case 2
A 51-year-old woman presented with a history of right hip problems dating back to age 13 years, when she sustained a fracture of the right hip and was treated with internal fixation. At age 15 years, she underwent proximal femoral osteotomy to correct residual deformity. She did well until age 45 years, when she developed worsening hip symptoms. Clinical findings and imaging studies were consistent with advanced degenerative arthritis of the right hip. Radiographs showed a fixed-angle blade plate in the proximal femur, with significant proximal femoral deformity (Figures 1C, 1D). Preoperative Harris Hip Score was 53.6.
Surgical Technique
In both cases, a standard series of radiographs was obtained—an anteroposterior (AP) radiograph of the pelvis and AP and cross-table lateral radiographs of the operative hip (Figure 1). Computed tomography (CT) with a metal-artifact-reducing technique may be useful in determining amount of cortical bone remaining under the plate. CT showed limited lateral cortex beneath the side plate and bony overgrowth covering the side plate. Preoperative templating was performed using previously described techniques.5
During THA, before removing any portion of any retained hardware, the surgeon should perform 3 important actions: Dislocate the hip, perform all appropriate capsular releases, and reduce the hip. Dislocating the hip before hardware removal significantly decreases the risk for fracture caused by stress risers, as the force required for dislocation is much more controlled because of the capsular releases. After hardware removal, the hip can be easily redislocated, and the femoral neck osteotomy can be performed.
When plate and screws are in an intracortical position, the screws can be removed only after removing the small shell of cortical bone covering them. The amount of bone to be removed is minimal. After the screws are removed, the plate remains in place. A motorized device with a metal-cutting attachment is used to transect the construct at the junction of the plate and barrel (case 1) or at the bend of a fixed-angle device (case 2). Laparotomy sponges are placed around the proximal femur to minimize the amount of soft tissue that could be exposed to metal shavings. Copious irrigation is used throughout this part of the procedure. Osteotomes are used to elevate the proximal portion of the plate and the barrel, preserving the distal portion of the plate on the lateral cortex of the femoral shaft.
After the head is removed, the rest of the THA can be performed using standard press-fit insertion technique (Figures 2A-2D). Care must be taken to ensure that the distal aspect of the femoral stem bypasses the most distal screw hole by at least 2 cortical diameters in order to reduce the risk for periprosthetic fracture.
