The Zweymüller threaded cup: a choice in revision? Migration analysis and follow-up after 6 years

Straight stem and threaded cup in patients under 60 years of age: 28.8-30.2 years of follow-up

Purpose

The aim of this retrospective observational study of one cohort was to evaluate the long-term outcome in patients younger than 60 years after total hip arthroplasty using a straight uncemented stem and an uncemented threaded cup.

Methods

Between 1986 and 1987, 75 hips of 75 patients (mean age, 53.35 ± 6.17 years) were consecutively implanted with an Alloclassic Zweymüller/Alloclassic SL stem and an Alloclassic CSF cup. Forty-four patients had died over the last 30 years. The remaining 31 patients (mean age, 82.9 ± 6.4 years) were reinvited for follow-up examinations. Clinical and radiographic evaluations were carried out.

Results

At a mean follow-up of 29.5 (28.8–30.2), 4 patients (5.3%) were lost to follow-up.

For the endpoint aseptic loosening (defined as the removal of stem or the cup for 2 cases), the overall survival rate is 97.3%. For the endpoint revision for any reason (22 patients), the survival rate is 70.6%. Eleven patients needed an exchange of head and liner, caused by wear. The average time from implantation until change of head and liner was 21.44 years (SD 5.92). Other reasons for revision surgery were septic loosening (3 cases), aseptic loosening of stem and cup (1 case), aseptic loosening of stem (1 case), periprosthetic calcification (2 cases), implant fracture (1 case), periprosthetic fracture (1 case), intraoperative fissure of stem (1 case), and total wear of liner including cup (1 case).

Conclusion

The combination of a straight stem (Alloclassic) and a screw cup (CSF) shows excellent results in young patients under the age of 60 at ultra-long-term follow-up at 30 years. Revisions due to wear of the polyethylene liner are more likely than in the older patients.

30-Years of experience with the cementless implanted Alloclassic CSF screw cup total hip arthroplasty system - An ultra-long-term follow-up

OBJECTIVE

The aim of this study was to evaluate our long-term results with the Alloclassic CSF screw cup total hip arthroplasty system. This is the first study to provide a 30-year follow-up, based upon our 30-year follow up study on the Alloclassic stem system.

METHODS

We reviewed 178 Alloclassic CSF screw cup systems, implanted in 171 patients from 1986 to 1987. The Zweymüller stem family was used in all cases. 136 patients had died over the last 30 years, so twenty-nine out of 35 patients being still alive, with a mean follow-up of 29,46 years (SD 0,48), were contacted by telephone and evaluated radiologically and clinically. Our loss-to-follow up was 17,14%. The mean age at follow-up was 83,01 years (72,4-95,2; SD 6,86).

RESULTS

If the endpoint is defined as the removal of the cup for aseptic loosening (3 cases), the overall survival rate is 98,31%. If the endpoint is revision for any reason (27 cases), the survival rate is 84,83%. Eleven patients needed an exchange of head and liner. The mean time from implantation until change of head and liner was 21,44 years (SD 5,92).

CONCLUSION

After 30 years of monitoring we can state that the evaluated system is very reliable in primary and secondary THA.

Cementless revision for infected hip arthroplasty: an 8.6 years follow-up

OBJECTIVE

To investigate cementless revision for postoperative infection after total hip arthroplasty (THA).

METHODS

From November 1997 to December 2009, 10 patients (10 hips; four males, six females) of mean age 58 years (36-73 years) with infection after THA were treated. Six of the 10 hips underwent revision total hip arthroplasty, two only received new acetabular components and two underwent stem revision. One-stage revision was performed in six cases and two-stage revision in four. Consecutive radiographs were compared to evaluate component conditions. Harris hip scores were determined before surgery and at final follow-up. Erythrocyte sedimentation rate and C-reactive protein were assessed.

RESULTS

All patients were followed up for a mean duration of 8.6 years (6.5-15.6 years). The mean Harris hip score improved from 35 (18-63) points preoperatively to 89 (60-99) points at final follow-up. No re-infection occurred. Femoral component exsertion was occurred in one asymptomatic patient. Hip joint pain resolved in seven cases; three patients had mild pain when walking long distances. At final follow-up, six patients still had slight limps. Heterotopic ossification developed in two hips. Mean polyethylene liner wear was 0.08 mm per year at final follow-up. Deep vein phlebothrombosis and nerve injury did not occur.

CONCLUSION

One- or two-stage revisions using cementless prosthesis can produce satisfactory clinical outcomes in patients with infection after THA. Whether the original prosthesis can be partially retained when attached tightly to the femur or acetabular bone needs further investigation.

High hip center technique using a biconical threaded Zweymüller cup in osteoarthritis secondary to congenital hip disease

BACKGROUND

The high hip center technique used for a deficient acetabulum is reconstruction of the hip at a high center of rotation. In the literature, there is no consensus regarding the value of this technique.

QUESTIONS/PURPOSES

We investigated whether the new-generation biconical threaded Zweymüller cup fixed in a high nonanatomic position in patients with arthritis secondary to congenital hip disease experienced different rates of polyethylene wear and long-term survivorship when compared with anatomically positioned cups.

PATIENTS AND METHODS

We studied the polyethylene wear rate and Kaplan-Meier survivorship of 104 titanium threaded Zweymüller cups in 88 patients (81 females), placed in 70 hips at near-normal hip center and in 34 hips at a high hip center position at a distance of 31.1 to 60 mm (mean, 39.7 mm) from the interteardrop line. Minimum followup was 2 years (mean +/- SD, 8.6 +/- 3.5 years; range, 2-15 years).

RESULTS

The mean linear polyethylene wear rates in the near-normal and high hip center groups were not different (0.110 +/- 0.050 mm and 0.113 +/- 0.057 mm, respectively). The Kaplan-Meier 15-year cup survivorship rates with revision for any reason as an event of interest in the near-normal and high hip center groups also were not different (97.2% [95% confidence interval, 88.5%-99.3%] and 97.1% [95% confidence interval, 73.8%-99.3%], respectively).

CONCLUSIONS

The high hip center technique using a biconical threaded Zweymüller cup in patients with arthritis secondary to congenital hip disease results in a polyethylene wear rate and long-term cup survivorship comparable to those observed in anatomically positioned cups.

LEVEL OF EVIDENCE

Level III, therapeutic study. See the Guidelines for Authors for a complete description of level of evidence.

[Comparison of different cup revision systems]

Aseptic loosening of hip cups results in cranial and medial migration, which induces bone resorption and defects. Despite these defects, it is the aim in cup revision arthroplasty to get a stable fixation and a restoration of the hip center. Depending on the size of the defect, which can be classified by different scoring systems, various strategies requiring an experienced surgeon can be used to reach this aim. If defects are localized, bigger primary cemented or cement-free cups can be used. Larger defects may need bone transplantation or special designs such as oval cups or reinforcement rings. They can be used with or without plates in combination with cement for inlay fixation. In the case of bigger defects or pelvic discontinuity, modular systems or a socket cup may be necessary.

Case reports: fractures of threaded cups: rare complications of a well-established implant

The use of cementless threaded cups in THA is a well-established treatment. Fractures of the cups are rare complications recorded in individual cases with material defects being discussed as the primary cause. We analyzed three cases of fractured cups. Although all three cups were well fixed to existing bone, we observed deficient osseous backing dorsocranially and abrasion particles. There were no signs of femoroacetabular impingement or infection. The cups showed corrosion debris. Scanning electron microscopic investigations showed characteristics of fretting and fretting-related corrosion. We concluded the fractures occurred because of fretting combined with inadequate bony support leading to fatigue of the material and subsequent fracture.