A seven- to 14-year follow-up study of bipolar hip arthroplasty in the treatment of osteonecrosis of the femoral head

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.

Mid-term results of short stem total hip arthroplasty in patients with osteonecrosis of the femoral head

PURPOSE

To evaluate the clinical and radiographic mid-term results of short-stem total hip arthroplasty (THA) in patients with osteonecrosis of the femoral head (ONFH).

METHODS

We reviewed 83 cases that underwent Metha stem between November 2010 and November 2012. The appearance of bone trabeculae development and radiolucent line were reviewed and HHS was recorded at 6 months postoperatively then yearly to evaluate the clinical results.

RESULTS

The mean age of patients was 43.8 years with the mean follow-up 69.3 (60-84) months. Harris Hip Score improved significantly from 44.7 preoperatively to 99.6 at the last follow-up (p < 0.0001). There were 4 cases (4.8%) of intraoperative femoral fractures. There was 1 case (1.2%) of distal stem perforation that had stable bone ingrowth and there was 1 case (1.2%) of 5-mm subsidence, which was then stable at 3 months postoperatively. Bone trabecular development was detected at zone 1 (65.1%), 2 (69.9%), 3 (14.4%), 4 (1.2%), 6 (97.6%) and 7 (81.9%). There was 1 case (1.2%) where radiolucent lines were observed in zones 1 and 7. There was 1 femoral stem revision from periprosthetic fracture 4 years after index surgery and 1 cup revision from aseptic loosening. Kaplan-Meier survivorship with the end point of stem revision for any reason was 98.8% and for aseptic loosening it was 100% at 7 years.

CONCLUSIONS

The mid-term clinical and radiographic results of the Metha stem in patients with ONFH were promising. Its design enables preservation of the bone stock and the bone trabeculae appear to confirm the assumption of proximal force transmission.

Comparison of Mid-term Survivorship and Clinical Outcomes between Bipolar Hemiarthroplasty and Total Hip Arthroplasty with Cementless Stem: A Multicenter Retrospective Study

Objectives

To compare the clinical outcome between bipolar hemiarthroplasty (BHA) and total hip arthroplasty (THA) using a U2 HA cementless hip stem, and the results of elderly femoral neck fracture patients who underwent BHA with a cementless hip stem.

Methods

A multicenter retrospective study enrolled 96 BHA and 115 THA cases using U2 HA cementless hip stems with mean age (BHA: 67.9 years; THA: 64.1 years), body height (BHA: 160.4 cm; THA: 160.7 cm) and weight (BHA: 62.7 kg; THA: 64.5 kg) recorded. Mean follow‐up durations were, respectively, 7.1 (BHA) and 7.8 (THA) years. Survivorship analyses and Oxford hip scores were compared.

Results

Both the BHA and the THA groups revealed high survival rates at 5‐year (100%) and 10‐year (100.0% and 90.1%) follow‐up. The THA group achieved better joint performance and pain relief. The cementless HA stems had survived perfectly for 10 years for elderly femoral neck fracture patients following BHA.

Conclusions

The U2 HA cementless hip stem provides an effective solution for both BHA and THA surgeries, and for elderly femoral neck fracture patients undergoing BHA. According to the findings of the current study, THA may be inadequate for addressing avascular necrosis, and pain control is a considerable concern for patients who have undergone BHA.

Cut-off values of latent infection in patients with rapid migration following bipolar hip hemiarthroplasty

BACKGROUND

Although most patients achieve favorable results following bipolar hip hemiarthroplasty (BHA), some experience rapid migration of the prosthesis. We retrospectively reviewed 18 patients with BHA that necessitated revision.

METHODS

We examined soft tissues obtained from periprosthetic lesions. In total, 18 patients with pain and acetabular migration of the BHA prosthesis were included. The patients were divided into a polymorphonuclear leukocyte (PMN)-positive (≥5 PMNs per high-power field [HPF]) and PMN-negative (<5 PMNs/HPF) group.

RESULTS

Pathological findings showed that 11 patients were PMN-positive, which was indicative of infection. All patients in the PMN-positive group showed no polyethylene particles or foreign body giant cells, while all patients in the PMN-negative group showed polyethylene debris or foreign body giant cells (p < 0.001). BHA survival, C-reactive protein (CRP) levels, and the Japanese Orthopaedic Association (JOA) hip score were significantly different between the PMN-positive and PMN-negative group (p < 0.01). A BHA survival cut-off value of 3270 days was diagnostic for PMN positivity (sensitivity: 100%; specificity: 100%). The cut-off values for CRP and the JOA hip score were 0.43 mg/dl and 56 points, respectively. Four of 11 PMN-positive patients showed no clinical symptoms of infection (asymptomatic PMN-positive group). BHA survival, CRP levels, and JOA hip scores were significantly different between the asymptomatic PMN-positive and PMN-negative group (p < 0.05). A BHA survival cut-off of 3270 days was diagnostic for asymptomatic PMN positivity (sensitivity: 100%; specificity: 100%). The cut-off values for CRP and the JOA hip score were 0.43 mg/dl and 57 points, respectively.

CONCLUSION

Our findings suggest that some portion of rapid BHA prosthesis migration is caused by mild infection. Careful pathological examination should be performed to identify infection before removal of the BHA prosthesis in patients who develop migration within 9 years.