We retrospectively identified all 72 patients with 75 symptomatic recurrent total hip dislocations who had surgery between 1998 and 2008. We defined “recurrent dislocations” as two or more dislocations that were not controlled with nonoperative treatment. We were unable to retrieve the exact number of episodes of dislocations for each patient from the records. Sixty-one of the patients were referred to us for treatment of recurrent dislocation and 11 were patients in the senior author’s (MDR) practice. Eight of the 11 patients in the senior author’s practice were revision THAs for other reasons that subsequently developed recurrent dislocations and three of the 11 developed recurrent dislocations after primary THA. Six of the 72 (8%) patients were either lost to followup or had incomplete records at the time of review. This left 66 patients who had operations on 69 hips. Fifty-two percent of patients were women and 48% men, and their ages ranged from 33 to 86 years. Patient body mass index (BMI) ranged from 17.9 to 53.5; 19% of patients had a BMI of 30 or more. Eleven (16%) hips had a previous history of infection, which had necessitated a two-stage revision surgery before the first episode of dislocation; the revision surgery for infection included removal of original hardware and implantation of an antibiotic-impregnated cement spacer, followed by reimplantation of hardware. Seventeen patients (25%) had abductor deficiency. We defined abductor deficiency as anatomic loss of the abductor muscle attachment to the proximal femur due to either trochanteric nonunion or segmental loss of proximal femoral bone stock. All of the patients had late dislocations (after 1 year); we treated dislocations before 1 year nonoperatively. The minimum followup was 2.8 years (mean, 7.81 years; range, 2.8–12.7 years). No patients were recalled specifically for this study; all data were obtained from medical records and radiographs.
During the study period, we performed one of four operations depending on the diagnosed problem: (1) correction of component malposition, (2) replacement of the femoral head with a large-diameter (36-mm) head, (3) trochanteric advancement, and (4) conversion of the acetabular component to a constrained implant. We chose not to use a bipolar prosthesis in this series since the bipolar bearing articulates with the native pelvis, which can result in pain and migration. The indications for each of the four surgeries differed, with the goal of identification and correction of the mechanical cause of instability. The indication for correction of component malposition was inadequate or excessive acetabular anteversion or vertical inclination, which we considered a cause of component impingement that resulted in instability (Fig. ). The indication for use of a large-diameter femoral head was adequately positioned components with a small (≤ 28-mm-diameter) femoral head (Fig. ). Trochanteric advancement was indicated in the setting of adequately positioned components where the femoral head size could not be increased. The trochanter was reattached using vertical and horizontal cables [12
]. We used this technique more frequently in the earlier phase of the study, when large-diameter femoral heads were not available (Fig. ). The indication for a constrained cup was complete loss of proximal femoral bone stock, including the abductor attachment in which the “jump height” was relatively easily exceeded, and when other revision procedures failed to control hip instability (Fig. ). We sutured the posterior capsule and short external rotators, if present, to the posterior border of the proximal femur or abductors, but there were no other specific soft tissue procedures performed to improve stability. We did not perform revision of the entire femoral component to correct inadequate offset or leg length in any patient.
Fig. 1A–D Radiographs illustrate the case of a 62-year-old woman who experienced recurrent anterior hip dislocations after primary THA despite use of a 36-mm femoral head. (A) An AP pelvic radiograph shows the position of the components. (B) A crosstable lateral (more ...)
Fig. 2A–B Radiographs illustrate the case of a 68-year-old man who developed recurrent dislocations after previous THA using a 28-mm femoral head despite correct implant position. (A) An AP radiograph shows the position of the components. (B) An AP radiograph shows (more ...)
Fig. 3A–B Radiographs illustrate the case of a 72-year-old woman who had undergone previous THA with a nonmodular femoral component and subsequent acetabular revision and developed recurrent anterior dislocations. (A) An AP radiograph shows the position of the (more ...)
Fig. 4A–B Radiographs illustrate the case of an 86-year-old man who had undergone multiple previous revision THAs complicated by infection and massive femoral and acetabular bone loss treated with removal of the components and insertion of an articulated antibiotic-impregnated (more ...)
We based the decision to use one or more techniques on the identification and correction of mechanical factors we considered the cause of instability (Fig. ). We considered trochanteric advancement contraindicated if bone stock in the greater trochanter was osteolytic or osteopenic, which could have led to greater risk of nonunion, and considered correction of malposition contraindicated if the components were well positioned based on preoperative AP pelvic and crosstable lateral hip radiographs. We considered use of a large head contraindicated if the acetabular component was too small to accommodate a large head or the femoral component was nonmodular; we did not perform femoral component revision. A constrained cup was considered contraindicated in any patient in whom mechanical abnormalities were identified that could be controlled with alternative techniques.
A chart shows the decision-making algorithm for surgical treatment of recurrent hip dislocations after THA based on factors that appeared to cause instability.
The senior author was the surgeon for all cases. The surgeon used four different surgical procedures to treat recurrent dislocations. To prevent “double counting,” we divided patients into two groups and studied them separately. The first group consisted of patients who received only a single technique, while the second group had a combination of techniques during the first operation to control instability.
The postoperative regimen was uniform for all patients. This included placement of an abduction pillow immediately after wound closure in the operating room, followed by early mobilization as soon as possible under the supervision of a trained physical therapist familiar with our practice (usually on the first postoperative day). Weightbearing was restricted to toe touch for 6 weeks after surgery in all patients. If we performed trochanteric osteotomy or bone grafting, we restricted weightbearing to 50% for an additional 6 weeks. We instructed all patients in either anterior or posterior hip precautions, depending on the preoperative pattern of instability, and advised against positioning the hip in extremes of range of motion (ROM).
Patients returned to clinic for a clinical and radiographic examination of the hip at 6, 12, 24, and 52 weeks postoperatively and then yearly thereafter. Radiographs included AP pelvic and lateral hip views. Polyethylene wear was not measured radiographically. The clinical examination included an assessment of gait, hip ROM, and strength at each visit.
For all patients, we recorded demographic and clinical data, including age, sex, BMI, history of previous ipsilateral hip infection, and abductor deficiency. The posterior surgical approach was used for every case. We defined success as the achievement of a stable hip and maintenance of stability for at least 2 years after surgery.
Treatment methods used were separated into three time periods during the study (Table ). Pearson’s chi square test was used to test for differences in proportions between patient demographics and revision techniques used during each time period.
Demographics and time period of treatment methods