Clinical results of hemiarthroplasty using new bipolar cups for stage 3 or lower osteonecrosis of the femoral head: a retrospective study

Long-Term Outcomes of Cementless Bipolar Hemiarthroplasty in Young Patients With Osteonecrosis of the Femoral Head: The Impact of Implant Improvements and Preoperative Stage

Introduction Advancements in bipolar hemiarthroplasty (BHA) implants in the mid-1990s contributed to favorable short-term outcomes for osteonecrosis of the femoral head (ONFH), particularly in cases without acetabular cartilage lesions. Nevertheless, long-term results remain unclear. In this study, we investigated (i) the impact of new-generation BHA implants and (ii) the effect of the preoperative stage on long-term outcomes in young patients with ONFH. Methods The records of consecutive patients with ONFH who underwent cementless BHA were retrospectively reviewed. Patients aged ≥60 years, with <10 years of follow-up, or who underwent acetabular reaming during surgery were excluded. Radiographical and clinical outcomes of patients who received first-generation BHAs and new-generation BHAs (developed after 1998) were compared by stratifying based on preoperative stage 2/3A and 3B/4, according to the Japanese Investigation Committee classification. Results Overall, 50 hips from 39 patients (mean age: 44.6 years; 64% male) with an average follow-up of 18.6 years were included. The frequency of advanced-stage patients was significantly higher in the first-generation BHA group than in the new-generation group. Regarding postoperative outcomes, the first-generation BHA group had higher acetabular erosion grades (p<0.001) and more femoral component loosening than those in the new-generation group (p<0.001). Revisions were performed in eight hips (seven in the first-generation and one in the new-generation BHA groups, p<0.001). In the new-generation BHA group, there were no significant differences in patient background between stage 2/3A and 3B/4 groups, and only one case in the stage 3B/4 group required revision. In the new-generation group, the grade of acetabular erosion was significantly higher for stage 3B/4 than stage 2/3A (p<0.001); other radiographical and clinical outcomes did not differ significantly between stages. Conclusion New-generation BHAs have significantly better implant survival rates for early-stage ONFH than those of first-generation BHAs. These findings indicate that BHA is an acceptable treatment option for early-stage ONFH in young patients.

The impact of increasing femoral offset and stem anteversion on postoperative dislocation in bipolar hemiarthroplasty

BACKGROUND

Femoral offset and anteversion have been reported to affect the incidence of dislocation following bipolar hemiarthroplasty, although the magnitudes of contributions of the femoral offset and stem anteversion on dislocation, both singly and in combination is not fully understood.

METHODS

Using the CT data of 61 patients (61 hips), including 30 male and 31 female who underwent bipolar hemiarthroplasty, three-dimensional dynamic motion analysis was performed using a modular implant that enabled adjustment of femoral offset and stem anteversion independently. The pattern of impingement and relationship between femoral offset/stem anteversion and range of motion were evaluated using the software.

FINDINGS

We found that a higher femoral offset and stem anteversion correlate with a greater range of motion of flexion and internal rotation. Furthermore, an increased femoral offset has a great effect on increasing range of motion of flexion than stem anteversion, and increased both femoral offset and stem anteversion have fewer effect on the flexion, whereas increasing stem anteversion has a great impact on internal rotation than offset, especially in the case with lower femoral anteversion. However, a higher stem anteversion decrease the range of motion of external rotation, whereas a higher femoral offset leads to an increased range of motion of external rotation.

INTERPRETATION

We demonstrated that both a higher femoral offset and stem anteversion substantially affected the range of motion in flexion, internal rotation and external rotation. However, these are not independent, but rather mutually confounding, the surgeons should consider retaining femoral/anterior offset in bipolar hemiarthroplasty.

Midterm results of revision total hip arthroplasty for migrated bipolar hemiarthroplasty in patients with hip osteoarthritis using cementless cup with the rim-fit technique

PURPOSE

The results of reamed bipolar hemiarthroplasty (BHA) in patients with hip osteoarthritis (OA) are reported to be unfavorable. Acetabular reaming for sufficient bony coverage caused bipolar head migration into the superomedial direction, and most patients required revision surgeries. Several methods are applicable to treat decreased bone stock. This study aimed to investigate the midterm results of revision surgeries using the cementless cup with the rim-fit technique.

METHODS

Between 1996 and 2014, acetabular revision surgeries using the cementless cup with the rim-fit technique were performed in 86 hips (74 patients). We evaluated radiographic outcomes, including positional change of the rotation center of the artificial femoral head, presence of implant loosening, and filling of the initial gap. We also evaluated clinical outcomes, including the Harris hip score (HHS), and postoperative complications.

RESULTS

The average positional changes from BHA to prerevision surgeries were 8.0 mm superiorly and 4.1 mm medially. The average changes from prerevision to postrevision surgeries were 3.7 mm inferiorly and 2.4 mm laterally. No implant loosening was found in all cases; the initial gap between the acetabular host bone and the acetabular cup was filled in 53 (93%) among 57 hips. The average HHS improved from 65.9 before revision surgeries to 83.8 in the latest follow-up. Dislocation and postoperative periprosthetic fracture occurred in two and five hips, respectively; no cases required rerevision surgeries.

CONCLUSION

There were favorable midterm results of the revision total hip arthroplasty for migrated BHA in patients with hip OA using cementless cup with the rim-fit technique.

Risk factors for radiological changes after bipolar hemiarthroplasty for osteonecrosis of the femoral head

OBJECTIVES

This study aimed to report the mid-term radiological outcomes of patients with bipolar hemiarthroplasty (BHA) for stage 3 osteonecrosis of the femoral head (ONFH), and to identify the risk factors for postoperative radiological changes.

METHODS

We retrospectively investigated 62 patients (38 men and 24 women; mean age, 50.1 years) aged <70 years who underwent primary BHA for Association Research Circulation Osseous stage 3 ONFH between 1998 and 2010. The mean follow-up period after BHA was 12.8 years. The following changes were assessed on follow-up radiographs: outer head migration, polyethylene wear, and femoral osteolysis. The association between demographic data and the development of postoperative radiological changes was evaluated.

RESULTS

Radiological changes were found in 20 hips (32.3%) at a mean of 8.1 years after BHA; of these, three hips (4.8%) underwent total hip arthroplasty conversion at a mean of 10.9 years after BHA. Both univariate and multivariate analysis revealed that younger age and female sex were independent risk factors for the development of postoperative radiological changes.

CONCLUSION

The current results suggest that the indication of BHA should be carefully determined in young or female patients with ONFH, even when the disease is in the early stage.

Histological evaluation of the acetabular labrum after bipolar hip hemiarthroplasty: a case report

We report herein the microstructure of the acetabular labrum obtained from a patient with stem loosening but without bipolar cup migration who had undergone hemiarthroplasty for femoral neck fracture 18 years ago. We used light and scanning electron microscopy to investigate the influence of bipolar cup on acetabular labrum in vivo. Deparaffinized blocks were treated with 2 N NaOH to digest the cell matrix, allowing the collagen fibers, constituting the acetabular labrum, to be observed under scanning electron microscopy. Although chondrocyte atrophy was seen, the basic structure was not different from the normal tissue images of the elderly. However, in the deep part of the acetabular labrum, there was an area that was not stained with Alcian blue observed with light microscopy, and there was an amorphous tissue without type II collagen fibrils observed with scanning electron microscopy. These findings proved that the acetabular labrum has partially degenerated over the long term after bipolar hemiarthroplasty, and that the acetabular labrum can survive in vivo in such a condition. Given that hemiarthroplasty has a possibility to preserve the face-to-face tissue in the long term in vivo, it may be one of the valuable options for modern or future joint reconstruction surgery.

[Total hip replacement in avascular femoral head necrosis]

BACKGROUND

Avascular necrosis of the femoral head is a progressive perfusion disorder of the hip joint. Progress in avascular necrosis causes structural damage to the affected joint, often requiring total hip replacement.

AIM

This article is intended to give the reader an overview of the current literature on total hip replacement of patients with an avascular necrosis of the femoral head.

RESULTS

Before 1990, patients with avascular necrosis of the femoral head had significantly higher revision rates after total hip replacement. Recent studies, however, showed no significant differences in clinical outcomes after total hip replacement in femoral head necrosis and primary osteoarthritis. Despite the young age of the patients, good long-term clinical results can be expected even in patients with an avascular necrosis of the femoral head after total hip replacement.