Posttraumatic conversion hip arthroplasties encompass a wide range of conditions from prior cannulated screw fixation for femoral neck fractures to complex posttraumatic acetabular deformities. Therefore, the reported outcomes are variable depending on the trauma type and fixation performed.
Patients seeking conversion hip arthroplasty after prior acetabular trauma are generally younger than patients undergoing total hip arthroplasty for primary hip osteoarthritis (Table 1). Romness and Lewallen studied 53 patients (55 hips) and found high rates of revision for aseptic loosening. In particular for patients younger than 60 years, they reported a 17.2% incidence of revision, whereas for patients older than 60 years, that rate was 7.7%. Weber et al reported on 66 hip arthroplasties performed for prior acetabular trauma and had 17 patients requiring revision (16 for aseptic loosening). In their study, age <50, body weight >80 kg, and large residual bone deficiencies of the acetabulum were risk factors for revision. In a study of 30 conversions for prior acetabular trauma, Bellabarba et al found a 97% survival rate at 10 years for radiographic loosening or revision. They showed those acetabular fractures treated surgically had greater surgical time, blood loss, and transfusion requirements than those treated nonoperatively, reflecting greater surgical complexity. Ranawat et al reported on 32 total hip arthroplasties performed for prior acetabular trauma. They found a 5-year survival rate of 79% with revision, dislocation, loosening, or infection as the endpoint. A 16% rate of infection was found in the immediate postoperative period, with all those patients having had prior infections during their acetabular trauma care. The authors also found that a history of infection was associated with ultimate loosening of the acetabular component and revision surgery. von Roth et al evaluated 25 patients with previous surgically treated acetabular fractures converted to total hip arthroplasty. At 20 years, they found that the survivorship of the acetabular component for revision for aseptic loosening was 71%, whereas survivorship free from revision for any reason was 57%. They encountered no additional complications during midterm follow-up and concluded that if early complications (ie, deep infection, dislocation) can be avoided, the risk of late complications outside wear-related issues is low. Yuan et al reported on 28 primary total hip arthroplasties performed with porous metal acetabular components after surgically treated acetabular fractures. They found that 5-year survivorship free of revision surgery was 88%. Three hips underwent resection for infection, and all three had undergone staged arthroplasty because of concern for infection. Partial sciatic nerve palsies were present in 23% of patients before total hip arthroplasty, and heterotopic ossification was present in 13%. After total hip arthroplasty, no patients had new sciatic nerve deficits, 7% (2 of 28) had early instability, and heterotopic ossification was present in 23% of hips. Morison et al provided follow-up on 74 patients who underwent total hip arthroplasty after acetabular trauma. Compared with case-controls performed for osteoarthritis or osteonecrosis, they found the acetabular trauma group to have a higher incidence of serious complications including infection, dislocation, loosening, and heterotopic ossification. Overall, these series show conversion arthroplasty for prior acetabular trauma to have varied results depending on patient age, severity of trauma, presence of infection, and previous surgical fixation, among other factors.
Proximal Femoral Trauma
Studies of conversion hip arthroplasty after prior proximal femoral trauma have shown heterogeneous results depending on prior fracture and fixation type (Table 2). These patients are older and less active than those undergoing hip arthroplasty for primary osteoarthritis.
Mabry et al provided follow-up on 84 patients who underwent Charnley total hip arthroplasty for management of femoral neck nonunion. They reported 93% survival free from revision for any reason at 10 years and 76% at 20 years. Age less than 65, BMI ≥ 30, and male sex were associated with revision for aseptic loosening. Dislocation was the second most common complication after implant loosening, occurring in 9% of patients. McKinley and Robinson compared 107 patients who underwent total hip arthroplasty as salvage after failed internal fixation for femoral neck fractures with a matched group who had undergone total hip arthroplasty acutely for femoral neck fractures. In their study, complications developed in 36% of the salvage arthroplasty patients within the first year postoperatively, with 17.8% needing revision surgery for these complications. They found that the conversion group had a markedly higher risk of superficial infection (odds ratio [OR], 4.0; 95% confidence interval [CI], 1.07 to 14.93), early dislocation (OR, 2.33; 95% CI, 1.02 to 5.32), and overall surgical complications (OR, 2.78; 95% CI, 1.50 to 5.55). Hernandez et al analyzed 62 patients who underwent conversion total hip arthroplasty after nonunion of percutaneously pinned minimally displaced femoral neck fractures. They observed two deaths within 90 days of the surgery, two intraoperative periprosthetic fractures, and four revision surgeries. Three of the revision surgeries were irrigation and débridement procedures for infection diagnoses, and one was a femoral component revision for aseptic loosening of a cemented femur 11 years after index arthroplasty. Five-year survivorship for revision surgery was 97% in their study. They reason that in looking at minimally displaced fractures, their patients had lower energy trauma and damage to the soft-tissue envelope than those in other studies, perhaps leading to lower dislocation and complication rates.
In multiple studies, conversion of prior intertrochanteric fracture fixation has been associated with poorer results than prior femoral neck fractures. Haidukewych and Berry reported on 60 patients who underwent salvage total hip arthroplasty for prior intertrochanteric fractures. They reported a mean surgical duration of 4 hours and estimated blood loss of 1,125 mL. Twenty percent of patients in their study had a postoperative medical complication, and they observed a 87.5% survival rate at 10 years. Archibeck et al reported on 63 total hip arthroplasty patients with prior femoral neck fractures and 39 with prior intertrochanteric fractures. They noted that revision type femoral components were used in 32% of these conversion cases. They observed four periprosthetic femur fractures (3.9%), and all were in the intertrochanteric conversion group. Mortazavi et al compared salvage arthroplasty for 71 intertrochanteric and 83 femoral neck fractures. They found that the intertrochanteric group had markedly longer surgical time (124 minutes versus 94), higher mean blood loss (659 mL versus 335 mL), and higher blood transfusion requirements (2.4 units versus 1.1).
Various studies have also evaluated differences in outcome based on type of initial trauma fixation. DeHaan et al reviewed 46 patients undergoing conversion hip arthroplasty. They noted that patients undergoing cannulated screw fixation had markedly lower revision implant usage, surgical time, and blood transfusion requirements than sliding hip screw or cephalomedullary nail conversions. Pui et al compared prior sliding hip screw and cephalomedullary nail conversions, finding a markedly higher rate of overall (41.9% versus 11.7%) and orthopaedic complications (29.0% versus 5.5%) in the cephalomedullary nail conversion group. Bercik et al evaluated the same question and found a higher surgical duration, blood loss, and revision stem usage in the cephalomedullary nail group. The authors reasoned that a cephalomedullary nail does greater damage to the medullary canal and the hip abductor mechanism than does a sideplate device and additionally may be more difficult to remove. They conclude that conversion from prior cephalomedullary fixation poses greater challenges and surgical complexity than does a sliding hip screw, and this should be considered at initial trauma fixation.
J Am Acad Orthop Surg. 2019;27(8):275-285. © 2019 American Academy of Orthopaedic Surgeons