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The Charnley versus the Spectron hip prosthesis: radiographic evaluation of a randomized, prospective study of 2
G Garellick1, H Malchau, H Regnér
1Department of Orthopaedics, Institute of Surgical Sciences, Sahlgrenska University Hospital, Göteborg University, Sweden.
Insights
This study compared Charnley and Spectron total hip arthroplasty, finding significant differences in component revision rates. Metal-backed cups showed poorer wear, suggesting avoidance in cemented hip arthroplasty.
Area of Science:
- Orthopedic Surgery
- Biomaterials Science
- Medical Device Engineering
Background:
- Total hip arthroplasty (THA) is a common procedure for hip osteoarthritis.
- Cemented femoral stems and acetabular cups are widely used in THA.
- Evaluating long-term outcomes of different THA components is crucial for clinical practice.
Purpose of the Study:
- To compare the long-term outcomes of Charnley and Spectron total hip arthroplasty systems.
- To assess the influence of component design, specifically metal-backing, on revision rates.
- To identify factors contributing to mechanical failure in cemented THA.
Main Methods:
- A randomized controlled trial involving 410 hips comparing Charnley and Spectron THA.
- Standardized surgical procedures with contemporary cementing techniques were employed.
- Radiographic evaluation and clinical follow-up at multiple intervals up to 10 years.
Main Results:
- Charnley stems showed higher rates of malalignment and poorer cement mantle quality compared to Spectron stems.
- Spectron metal-backed cups exhibited significantly higher loosening and revision rates than Charnley ogee cups.
- Overall revision rates differed significantly between the femoral (Charnley higher) and acetabular (Spectron higher) components.
Conclusions:
- Metal-backing of cemented acetabular cups, particularly with larger femoral heads, should be reconsidered due to poor wear characteristics and high failure rates.
- Difficulties in positioning the Charnley stem may contribute to its inferior long-term performance.
- These findings have implications for the selection of cemented THA components to optimize patient outcomes.
Abstract:
A total of 410 hips were randomized to treatment with either a Charnley (206 hips) or a Spectron (204 hips) total hip arthroplasty. The patients were operated on by a standardized procedure using a contemporary cementing technique and were followed after 1, 3, 5 to 6, and 10 years. The postoperative radiographs showed a significantly increased rate of malalignment and consequently low grade of cement mantle quality of the Charnley stem compared to the Spectron. No differences concerning cement mantle quality or positioning were found between the Charnley ogee cup and the metal-backed Spectron. Evaluation of the follow-up radiographs revealed 10 loose Charnley stems and 1 loose Spectron stem and 4 loose Charnley ogee cups and 23 loose Spectron metal-backed cups. The differences of revision rate for the femoral and acetabular components of the 2 prostheses were significant (P = .03, Charnley femoral component more frequent; P = .03, Spectron acetabular component more frequent). The radiographic evaluation strengthened this disparity. Poor wear characteristics of the metal-backed Spectron cup are perhaps the main reason for the highly significant difference in mechanical failure rate between the 2 cups. We therefore propose that metal-backing of cemented cups should be avoided, at least when combined with larger femoral heads. The difficulty in positioning the Charnley stem with an adequate cement mantle, especially in the absence of trochanteric osteotomy, might explain the inferior Charnley stem longevity in this study.