The most important findings of this study were that patients undergoing salvage THA after failed internal fixation required more operative time, suffered more blood loss, and had later ambulation. This salvage THA group was also at high risk of early periprosthetic dislocation, periprosthetic infection, reoperation and revision. Most dislocations occurred within 6 months, and most revision THAs were performed within 2 years after the first THA. The subgroup analysis also found that patients with previous intertrochanteric fractures had longer operative times, more postoperative persistent hip pain, and more complications than patients with previous femoral neck fractures and acetabular fractures.
The greater blood loss and longer operative time in the salvage THA group may reflect the blood loss status during the operation. Compared to primary THA, the surgical steps for salvage THA were more complicated, including the additional step of removing previous implants, which may have contributed to more blood loss and longer operative time. In addition, salvage arthroplasty is more technically challenging than primary arthroplasty because the hip is frequently stiff. The adhesive soft tissue and poor bone quality resulted in difficulty in exposure, prolonged operating time, increased blood loss, and increased risk of intraoperative fracture .
The postoperative day to ambulate and length of stay may promptly reflect the short-term outcomes after THA. Patients with salvage THA may have impaired progression of the center of pressure and a greater loss of abduction strength in a gait analysis . Our cohort showed that the delay of ambulation was significant. Although a previous study showed a 1.5-day longer hospital stay , we did not find a significant difference in our comparison. This was possible because we followed the principles of enhanced recovery after surgery (ERAS) to facilitate recovery after THA .
Prosthetic dislocation was one of the most common causes of revision in those who underwent secondary THA after failed fixation. The previous dislocation rate after salvage THA was reported to be 5–19.6% [7, 8, 10, 12, 25, 27]. We found a significantly higher dislocation rate of 9.5% in the salvage THA group than in the primary THA group since poor bone quality in salvage THA causes worse osseointegration. Most of the dislocations occurred within 6 months after salvage surgery. We suggest tightening the soft tissue envelope, repairing the capsule, and reconstructing external rotators during the operation to reduce dislocation risk. Furthermore, emphasis on postoperative hip precaution for at least 3–6 months is important.
A high reoperation rate was reported for THA following internal fixation for proximal femoral fracture [23, 28], with an estimated rate of 18% shown by a recent meta-analysis . Our reoperation rate of salvage THA was 10.5%, but it was also higher than that for primary THA. The most common reason for both reoperation and revision was prosthetic dislocation.
Patients who received salvage arthroplasty after failed internal fixation for fractures had a greater prevalence of complications, leading to a greater need for revision THA [7, 25]. In our study, six patients (5.7%) in the salvage THA group eventually required revision surgery. Three patients underwent revision THA for repeated dislocation, and the other 3 underwent revision THA for deep infection, including 1 patient who had deep infection after open reduction surgery for dislocation. All revision THAs occurred within 2 years after salvage THA. A prior study also showed worse survival outcomes in salvage arthroplasty at both five and ten years .
Most previous reports of salvage THA only included patients with proximal femur fractures. We also enrolled 30 (28.6%) salvage THAs after acetabular fracture. These patients were younger and more likely to be male because acetabular fractures are mainly caused by high-energy events , and most of our patients were injured in major traffic accidents. After THA, these patients tended to recover well and had less persistent hip pain.
Patients with previous intertrochanteric fractures were the oldest group. Salvage THA in this group required a longer operative time. Elderly patients tended to have a higher incidence of chronic and neuropathic pain . Postoperative pain could exacerbate the condition because of the double crush phenomenon . Therefore, salvage procedures after failed fixation for intertrochanteric fractures might be more problematic [19, 32]. During the follow-up period, persistent hip pain was noted in most patients (83.8%), even 3 months after THA. We also found a trend of more complications, including poor wound healing, infection, and dislocation, in this group.
The limitation of this study is the difficulty in performing a randomized controlled trial for this issue. We designed a 1–2 sex- and age-matched comparison to minimize selection bias. Because this was a single tertiary center cohort, we could analyze the details of comorbidities, types of fracture, survival free from dislocation and revision. All patients followed the clinical pathway in our institution, and the operations were executed by experienced orthopedic surgeons. We focused on the THA revision rate and subgroup analysis, reflecting the actual clinical condition, which has rarely been discussed in the previous literature.
In conclusion, we reported acceptable outcomes of salvage THA after failed internal fixation of fractures. Compared with primary THA, salvage THA requires more operative time, causes more blood loss, delays ambulation, and results in a higher risk of early prosthetic dislocation, reoperation, and revision THA. Subgroup analysis of different etiologies found that patients with previous intertrochanteric fracture might be the most susceptible to postoperative complications.