Strategies for head and inlay exchange in revision hip arthroplasty

Proof of Concept of a New Revision Procedure for Ceramic Inlays of Acetabular Cups Using a Shape-Memory Alloy Actuator System

The revision of ceramic inlays of acetabular cups is a challenging surgical procedure. The mechanical impact during the inlay extraction process can damage the ceramic or metal cup rim. To avoid these risks, a concept for a new revision procedure was developed. It is based on an actuator system, which allows a non-destructive release of the ceramic inlay. To integrate the actuator system, different design concepts of acetabular cup components were investigated, and an actuator based on shape-memory alloy (SMA) wires was developed. The process chain for the actuator, starting from nickel-titanium wires manufactured into the actuator geometry by laser welding and thermo-mechanical treatment for the shape setting process up to the functionality evaluation of the actuator system, was implemented on a laboratory scale. The new revision procedure is based on a phase transformation of the SMA wire actuator, which was obtained through two methods-applying an electrical current by an instrument and rinsing the wire with heated water. The phase transformation of the actuator resulted in a contraction between 3.2% and 4.3% compared to its length after pre-stretching and was able to release the ceramic inlay from the cup. Therefore, the developed actuator design and process chain is a proof of concept towards a new revision procedure for modular acetabular cups.

Systemic toxicity eliciting metal ion levels from metallic implants and orthopedic devices - A mini review

The metal/metal alloy-based implants and prostheses are in use for over a century, and the rejections, revisions, and metal particle-based toxicities were reported concurrently. Complications developed due to metal ions, metal debris, and organo-metallic particles in orthopedic patients have been a growing concern in recent years. It was reported that local and systemic toxicity caused by such released products from the implants is one of the major reasons for implant rejection and revision. Even though the description of environmental metal toxicants and safety limits for their exposure to humans were well established in the literature, an effort was not adequately performed in the case of implant-based metal toxicology. Since the metal ion concentration in serum acts as a possible indicator of the systemic toxicity, this review summarizes the reported human serum safe limits, toxic limits, and concentration range (μg/L, ppb, etc.) for mild to severe symptoms of six (cardiac, hepatic, neuro, nephron, dermal and endocrine) systemic toxicities for twelve most commonly used metallic implants. It also covers the widely used metal ion quantification techniques and systemic toxicity treatments reported.

Metallosis after Exchange of the Femoral Head and Liner following Ceramic Acetabular Liner Dissociation in Total Hip Arthroplasty with a Modular Layered Acetabular Component

The type of bearing material that should be used in revision surgery after the failure of ceramic-on-ceramic total hip arthroplasty (THA) remains controversial. In the case of ceramic fracture, the residual ceramic particles can cause consequent metallosis when metal implants are used for revision THA. On the other hand, in the case of THA failure without ceramic fracture, revision THA with a metal femoral head provides satisfactory results. We report an unusual case of progressive osteolysis due to metallosis that developed after revision THA for ceramic liner dissociation without a liner fracture performed using a metal femoral head and polyethylene liner. The residual metal debris and abnormal pumping motion of the polyethylene liner due to the breakage of the locking system or the aspherical metal shell being abraded by the ceramic head seemed to be the cause of the progressive osteolysis.

Cementless Revision Total Hip Arthroplasty with Ceramic Articulation

Purpose

The results of ceramic-on-ceramic (CoC) bearing surfaces in primary total hip arthroplasty (THA) were well known. However, it was not known in revision THA. The purpose of this study is to report the results of revision THA with ceramic articulation.

Materials and Methods

A total of 112 revision THAs were evaluated. The mean age at the time of surgery was 51.6 years (27.7 to 84.2 years). The mean duration of the follow-up periods was 6.3 years (2.3 to 11.4 years).

Results

The Harris hip scores improved from an average of 56.2 at the index surgery to an average of 93.3 at the last follow-up (P<0.001). None of hips showed osteolysis or ceramic head fracture. One hip showed aseptic loosening in the acetabular component with squeaking that caused a re-revision. There were nine cases of dislocation. The survivorship at 5 years was 94.5% (95% confidence interval, 87.9% to 97.6%) with revision for any reason as the endpoint and 100% with femoral revision.

Conclusion

The ceramic articulation is one of good bearing options for revision THA in patients with a long life expectancy.

Long-term durability of alumina ceramic heads in THA

BACKGROUND

The optimal type of bearing for hip arthroplasty remains a matter of debate. Ceramic-on-polyethylene (CoP) bearings are frequently used in younger and more active patients to reduce wear and increase biocompatibility compared to Metal-on-Polyethylene (MoP) bearings. However, in comparison to metal heads, the fracture risk of ceramic heads is higher. In addition, ceramic head fractures pose a serious complication which often necessitates major revision surgery. To date, there are no long-term data (>20 years of follow-up) reporting fracture rates of the ceramic femoral heads in CoP bearings. The purpose of this research was to investigate long-term CoP fracture rate.

METHODS

We evaluated the clinical and radiographic results of 348 cementless THAs treated with 2nd generation Biolox Al₂O₃ Ceramic-on-Polyethylene (CoP) bearings consecutively implanted between January 1985 and December 1989. The mean age at implantation was 57 years. The patients were followed for a minimum of 20 years. At the final 111 had died, and 5 were lost to follow-up. The cumulative incidence of ceramic head fractures in the long-term was estimated using a competing risk analysis.

RESULTS

The cumulative incidence of ceramic head fracture after 22-years was estimated with a competing risk analysis at 0.29% after 22-years (SE = 2.09%; 95% - CI: 0.03-1.5%). The radiographic analysis revealed no impending failures at final follow-up.

DISCUSSION/CONCLUSION

The fracture rate of second-generation ceramic heads using a CoP articulation remains very low into the third decade after cementless THA.

Two-year follow-up of revision total hip arthroplasty using a ceramic revision head with a retained well-fixed femoral component: a case series

Introduction

It is known that a well-fixed stem can be left in situ when only the acetabular component and femoral head have to be changed. However, in a revision case, the use of a ceramic head on an existing taper is not recommended. Slight damages of the taper may increase the risk of a ceramic fracture. Until now in a revision case a primary ceramic-on-ceramic or ceramic-on-polyethylene pairing was changed to a metal-on-polyethylene pairing or the well-fixed stem was removed as well. During the past several years, a ceramic head with a metallic sleeve has been introduced as an option for revisions with a stem left in situ. We report short-term results of a ceramic revision head in this clinical setting.

Methods

Eight patients with a ceramic revision head were clinically and radiologically followed up two years after revision surgery. Their Harris Hip Score and visual analogue scale scores for pain and satisfaction were recorded, and their radiographs were checked for osteolysis and heterotopic ossifications.

Results

The mean Harris Hip Score increased from 46.5 points before surgery to 88.3 points 2 years after surgery. The mean visual analogue scale score for pain improved from 6.7 to 1.1, and the mean visual analogue scale for satisfaction rose from 5.1 to 8.3. The radiological results did not show osteolysis in any of the patients. Grade I heterotopic ossification according to the Brooker classification system was seen in one patient.

Conclusions

The early clinical and radiological results in this case series are in agreement with previously published studies. Ceramic revision heads with a metallic sleeve are a promising approach in the revision of a ceramic head with a well-fixed stem which can be left in situ. This solution avoids an unnecessary exchange of a well-fixed stem and thereby shortens the surgical time of the revision and may reduce the peri-operative complications.

Alumina heads minimize wear and femoral osteolysis progression after isolated simple acetabular revision

BACKGROUND

Patients with THA requiring cup revision for acetabular osteolysis may have a stable stem component without loosening. However, it is unclear whether isolated cup revision halts femoral osteolysis progression.

QUESTION/PURPOSES

We asked (1) whether and to what degree osteolysis progresses after isolated acetabular revision with a change of the femoral head and (2) whether an alumina or metal bearing better reduces osteolysis progression and wear with a polyethylene (PE) cup.

METHODS

We retrospectively evaluated 150 patients who underwent 165 acetabular revisions but no treatment for proximal femoral osteolysis in hips with stable femoral components. Mean age at revision was 63 years (range, 48-74 years). All hips received a new PE cup; 83 hips received new alumina heads and 82 new metal heads. Radiographs (mean followup, 15 years; range, 10-25 years) were assessed to measure osteolysis, loosening, and PE wear. Revisions of the femoral stem were recorded.

RESULTS

An isolated cup revision with a change of the femoral head halted femoral osteolysis progression for 10 years in 133 hips (81%), with a greater percentage without progression in hips with alumina heads (99% versus 62% with metal head). Alumina heads were better than metal heads at reducing the area of osteolysis progression (47 versus 250 mm(2)) and wear (0.07 versus 0.14 mm/year) and increasing the survival probability before femoral revision (98% versus 85% at 15 years' followup).

CONCLUSIONS

An isolated cup revision with a new alumina femoral head (in hips that have a stable stem component without loosening) usually halts femoral osteolysis progression (no change or osseous restoration) over 10 years if the osteolysis is less than 1000 mm(2).

LEVEL OF EVIDENCE

Level III, therapeutic study. See Instructions for Authors for a complete description of levels of evidence.

Advantages and disadvantages of ceramic on ceramic total hip arthroplasty: a review

BACKGROUND

Ceramic on ceramic (COC) total hip arthroplasty (THA) was developed to reduce wear debris and accordingly, the occurrence of osteolysis and aseptic loosening especially in younger patients. Based on the excellent tribological behavior of current COC bearings and the relatively low biological activity of ceramic particles, significant improvement in survivorship of these implants is expected.

METHODS

We used manual search to identify all relevant studies reporting clinical data on COC THAs in PubMed. The objective was to determine whether current COC THA offers a better clinical outcome and survivorship than non-COC THA.

RESULTS

Studies with early generation ceramic bearings yielded 68% to 84% mean survivorship at 20 years follow-up which is comparable with the survivorship of non-COC THAs. Studies on current ceramic bearings report a 10-year revision-free interval of 92% to 99%. These outcomes are comparable to the survivorship of the best non-COC THAs. However, there are still concerns regarding fracture of sandwich ceramic liners, squeaking, and impingement of the femoral neck on the rim of the ceramic liner leading to chipping, especially in younger and physically active patients.

CONCLUSION

Current COC THA leads to equivalent but not improved survivorship at 10 years follow-up in comparison to the best non-COC THA. Based on this review, we recommend that surgeons weigh the potential advantages and disadvantages of current COC THA in comparison to other bearing surfaces when considering young very active patients who are candidates for THA.