Hip Replacement -Bipolar Endoprosthesis

Surgical treatment of avascular necrosis (AVN) of head of femur include core decompression, osteotomies, nonvascularized bone grafting, free vascularized fibular grafts, hip resurfacing, bipolar hip arthroplasty (BHA) and total hip arthroplasty (THA).,, THA is indicated in the young individual in AVN with acetabular involvement; however, its role is unclear in cases without acetabular involvement. BHA was initially limited to be used in hip osteoarthritis, nonunions and acute neck femur fractures., Bateman and Giliberty were first to use BHA in Ficat Stage 3 AVN based on the hypothesis that “acetabular floor retains a regenerative property, which regenerates bone in the subchondral region, if stimulation in the form of weight bearing is given through an accurately fitted cup” and theorized that preferential motion at inner bearing will decrease the cartilage erosion. Papers have been published with both satisfactory,,,,, and unsatisfactory results using BHA.,,, The main limitations sighted are migration of the outer cup (secondary to the acetabular erosion) and unpredictable pain relief.,, Incidence of groin pain varied from 11.5% to 42%,, and incidence of acetabular erosion and protrusio is reported to range from 0% to 45%., The activity of the patient and the duration of followup determine the erosion of acetabulum and appearance of symptoms. However, the main issue seems to be motion between the outer cup and the acetabulum, a nonconcentric acetabulum and particulate wear.,,, To decrease this motion between the outer cup and the acetabulum a gentle reaming of the acetabulum with insertion of tight fitting acetabular cup can be done as suggested above by Bateman and Giliberty., This is thought to decrease the incidence of groin pain and the acetabular erosion and also revision secondary to these issues., In this retrospective series, we have assessed the midterm outcome of BHA in young adults (age

Bipolar versus total hip endoprosthesis: Functional results

Biomechanics of bipolar hip endoprostheses. - Medscape

BIPOLAR ENDOPROSTHESIS FOR OSTEONECROSIS OF …

Surface replacement is an option in younger people with AVN, but has limited indications and is a demanding procedure with high cost. The results published by for surface replacement are not uniform and a longterm followup is lacking.,, THA is the method of choice for the treatment of advanced AVN of the femoral head;,, however, its overuse may lead to increased wear and need for early revision in young adults. Various studies have shown that functional utility of THA reduces to 80% at 10 years, 33% at 16 years, subsequently requiring a revision surgery. Alternate bearing surfaces like metal on metal or ceramic on ceramic decrease the wear rate but have their own set of complications (metallosis, squeaking),,,,,,, and long term results are still awaited. When compared with BHA, conflicting results have been reported. Chan and Shih have reported that there was no difference in the incidence of osteolysis, thigh or groin pain, dislocation rates and revision rates between BHA and THA. They concluded that in young patients with Ficat Stage 3 AVN, BHA may be a useful alternative to THA. Furthermore, BHA is less demanding, blood loss is comparatively less and revision is easier as compared with the revision of THA as the acetabulum is still intact. Lee et al. have reported 23% outer cup migration rate, 15% gluteal pain and 20% groin pain in BHA. Ito et al. have reported 42% radiological failures, 42% incidence of groin pain requiring a revision surgery in 25% hip undergoing BHA. Similar results were shown by Cabanela and Lachiewicz and Desman with groin pain and acetabular erosion as the two most important reasons for poor results in BHA. Groin pain has been variably attributed to the preservation of diseased joint capsule, to irritation of the subchondral nerve endings of the acetabulum and to the acetabular erosion., In our study, the diseased capsule was always excised to avoid capsular impingement. Furthermore, as nerve endings in the posterior capsule supply the acetabulum, excising it blocks the nerve supply to the acetabulum and thus helps in relieving pain. Poor fitting bipolar prostheses can lead to cartilage necrosis giving rise to groin pain and degeneration., Acetabular erosion has also been attributed to a fair amount of movement at the outer bearing due to a wide surface of the cup, which was greater than two third of a sphere., Reaming in BHA technique creates a better fit that reduces movements between the outer cup and the acetabulum and ensures that on weight bearing, movements are transmitted to the inner bearing. In effect, this works like a low friction arthroplasty and results in reduced pain and damage to the acetabular bone stock. This also explains the low incidence of acetabular migration and low revision rate in our series. Dudani et al. too used the same technique and reported 80% good result at average follow of 7.2 years. However, some reports have stated that reaming may not necessarily work. Pellegrini et al. have reported a higher risk of revision with acetabular reaming while Muraki et al. concluded that acetabular reaming increases the tendency of superomedial migration. We did not find these in our series. The uniformly good results at the mid term seen in our series may be attributed to the technique and amount (depth) of reaming. Pellegrini et al. reamed the acetabulum till a depth when the osseous floor showed punctuate bleeding. We have used a more conservative reaming without breaching the integrity of the subchondral bone, and this is probably why we have low incidence and magnitude of medial migration. On the contrary [] the subchondral bone shows sclerosis, asserting the Bateman hypothesis regarding the regenerate potential of acetabulum. In our series, ten patients showed this sclerosis. Nagai et al. in 12-18 years old followup study of nonself centering Bateman bipolar endoprosthesis for nontraumatic osteonecrosis of the femoral head concluded that the original Bateman endoprosthesis was effective in delaying the need for THA for more than 10 years in Ficat Stage 3 AVN of the femoral head. However, the sample size was very small, with 4 out of 12 patients having some groin pain and study limited to Ficat stage III AVN only. In another study Tsumura et al. found no difference in clinical results however incidence of migration in Ficat 2 and 3 stage was less when compared with stage 4. Based on this they recommended BHA only for Ficat Stages 2 and 3. In our study, we have used BHA for both stages 3 and 4 stages. Although the final range of motion was better in Ficat Stage 3 group, the final HHS was similar in both the groups showing effectiveness of BHA with tight fitting cup in both Ficat 3 and 4 stages. Thus, even in cases with acetabular involvement this technique can be used with good clinical results and can defer the need for THA.

Bipolar Endoprosthesis for Osteonecrosis of the …

On subgroup analysis between the Ficat Stages 3 and 4 [] it was noted that hips with Ficat Stage 3 were younger at the time of surgery and also had better final outcome in terms of range of motion. The final HHS score was however not statistically different in both groups indicating good results even in cases with acetabular involvement. None of the Ficat Stage 3 patients had any groin pain or femoral subsidence at the final followup while 4 cases of groin pain and 8 cases of femoral subsidence were seen in Ficat Stage 4 group. Figures to show case series with final result of four patients in our series.

Another much less common indication to use a bipolar hip replacement is when a …
Hemiarthroplasty of the hip using a low friction bipolar endoprosthesis

Bipolar hip arthroplasty for avascular necrosis of …

Bipolar hip arthroplasty using tight fitting cup for AVN hip has a low incidence of groin pain, acetabular erosion, and revision in midterm followup. This procedure can be used for treatment in young adults with Ficat Stages 3 and 4 AVN of the femoral head to defer a definitive THA. Further large series with long term followups, multicentric randomized studies and reproducibility of results will be needed to establish this method.

Reconstruction options using hip arthroplasty include unipolar or bipolar ..

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The radiological evaluation comprised of looking for subsidence of the stem, recording of any evidence of stem loosening in the form of a radiolucent line surrounding the stem and superior or medial migration of the cup. AP X-rays were taken with the patient lying supine with the hip in neutral and abduction position to check for movement in inner and outer bearing as shown [Figure and ]. The femoral component subsidence was evaluated by measuring the distance between the superior margin of the greater trochanter and the shoulder of the stem. Medial migration of the bipolar cup was determined from the distance between a line perpendicular to Kohler's line and center of the outer head, whereas superior migration was indicated by a change in distance between the inter teardrop line and the centre of outer head means centre of the circle that is calculated from the circumference of outer cup of bipolar prosthesis that is easily outlined on the radiograph. All radiographic measurements were done by either of two authors on AP radiograph of the hip and were compared to the immediate postoperative radiographs. A subgroup analysis was also done, by dividing the cohort according to Ficat's class, to evaluate the effect of acetabular involvement on the outcome of the procedure.

Unipolar, Bipolar or Total Hip Endoprosthesis after Femoral Neck Fracture: What is a Right Decision?

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These results suggest that cementless press-fit bipolar endoprosthesis for osteonecrosis demonstrate high incidence of acetabular protrusio and osteolysis.