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Reconstruction of the rotation center of the hip after oblong cups in revision total hip arthroplasty.

García-Rey E, Fernández-Fernández R, Durán D, Madero R - J Orthop Traumatol (2012)

Bottom Line: We assessed the clinical results and the survival rate for revision and aseptic loosening.The mean distance between the center of the femoral head prosthesis and the approximate center of the femoral head improved from 21.5 to 10.2 mm.Excessive medialization of the cup may increase the rate of loosening.

View Article: PubMed Central - PubMed

Affiliation: Department Orthopaedics-IDi Paz, Hospital La Paz, P° Castellana 261, 28046 Madrid, Spain. edugrey@yahoo.es

ABSTRACT

Background: The preoperative bone defect and the reconstruction of the center of rotation of the hip are critical in acetabular revision surgery. Uncemented oblong cups are employed in order to manage these issues. We analyzed the clinical results and rates of revision of two different uncemented oblong cups, the reconstruction of the center of rotation of the hip, as well as the rate of radiological loosening and possible risk factors.

Materials and methods: Forty-five patients (46 hips) underwent acetabular revision surgery using two different uncemented oblong cups. We assessed the clinical results and the survival rate for revision and aseptic loosening. Intraoperative bone loss was classified according to Paprosky, and acetabular reconstruction was assessed according to Ranawat. The mean follow-up was 7.2 years (range 4-11 years).

Results: There were four re-revisions (three due to aseptic loosening); the survival rate for re-revision due to aseptic loosening was 60.1 % at seven years. The mean distance between the center of the femoral head prosthesis and the approximate center of the femoral head improved from 21.5 to 10.2 mm. Thirteen cups showed radiological loosening; the survival rate for radiological loosening at seven years was 40.54 %. A smaller postoperative horizontal distance was correlated with cup loosening.

Conclusions: Although optimal acetabular reconstruction can be achieved by using oblong uncemented cups in revision hip surgery, the clinical and radiological results are not encouraging. Excessive medialization of the cup may increase the rate of loosening.

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Radiographs showing acetabular reconstruction using a BOFOR cup. a Preoperative radiograph showing the center of rotation outside Ranawat’s triangle. b Postoperative radiograph showing the center of rotation inside Ranawat’s triangle
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Fig2: Radiographs showing acetabular reconstruction using a BOFOR cup. a Preoperative radiograph showing the center of rotation outside Ranawat’s triangle. b Postoperative radiograph showing the center of rotation inside Ranawat’s triangle

Mentions: Regarding the acetabular reconstruction, Table 2 shows all of the radiological parameters evaluated for each patient. The radiological analysis showed a mean preoperative acetabular abduction angle of 65.9° (range 35–100), a mean horizontal distance of 34.7 mm (range 5–60), and a mean vertical distance to the center of the femoral head of 34.3 mm (range 5–70). After hip revision surgery, the mean postoperative acetabular abduction angle was 48.6° (range 35–80), the horizontal distance was 31.5 mm (range 5–40), and the height of the center of the hip was 23.2 mm (range 5–45). We also observed that, on the preoperative radiographs, 33 hips were outside Ranawat’s triangle and 12 were inside, while on the postoperative radiographs 37 were inside and 8 were outside (Fig. 2). The mean distance between the center of the femoral head prosthesis and the AFHC improved from 21.5 mm (range 5–45) to 10.2 mm (range 0–25) (Table 3). Acetabular reconstruction was achieved in most hips regardless of bone defect (Table 4). The mean height of the center of the hip showed greater improvement with bone defect types 2C and 3 than with type 2B; the other parameters—the acetabular abduction angle, the horizontal distance, and the mean CPFH–AFHC distance—improved in the same manner.Table 2


Reconstruction of the rotation center of the hip after oblong cups in revision total hip arthroplasty.

García-Rey E, Fernández-Fernández R, Durán D, Madero R - J Orthop Traumatol (2012)

Radiographs showing acetabular reconstruction using a BOFOR cup. a Preoperative radiograph showing the center of rotation outside Ranawat’s triangle. b Postoperative radiograph showing the center of rotation inside Ranawat’s triangle
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3585906&req=5

Fig2: Radiographs showing acetabular reconstruction using a BOFOR cup. a Preoperative radiograph showing the center of rotation outside Ranawat’s triangle. b Postoperative radiograph showing the center of rotation inside Ranawat’s triangle
Mentions: Regarding the acetabular reconstruction, Table 2 shows all of the radiological parameters evaluated for each patient. The radiological analysis showed a mean preoperative acetabular abduction angle of 65.9° (range 35–100), a mean horizontal distance of 34.7 mm (range 5–60), and a mean vertical distance to the center of the femoral head of 34.3 mm (range 5–70). After hip revision surgery, the mean postoperative acetabular abduction angle was 48.6° (range 35–80), the horizontal distance was 31.5 mm (range 5–40), and the height of the center of the hip was 23.2 mm (range 5–45). We also observed that, on the preoperative radiographs, 33 hips were outside Ranawat’s triangle and 12 were inside, while on the postoperative radiographs 37 were inside and 8 were outside (Fig. 2). The mean distance between the center of the femoral head prosthesis and the AFHC improved from 21.5 mm (range 5–45) to 10.2 mm (range 0–25) (Table 3). Acetabular reconstruction was achieved in most hips regardless of bone defect (Table 4). The mean height of the center of the hip showed greater improvement with bone defect types 2C and 3 than with type 2B; the other parameters—the acetabular abduction angle, the horizontal distance, and the mean CPFH–AFHC distance—improved in the same manner.Table 2

Bottom Line: We assessed the clinical results and the survival rate for revision and aseptic loosening.The mean distance between the center of the femoral head prosthesis and the approximate center of the femoral head improved from 21.5 to 10.2 mm.Excessive medialization of the cup may increase the rate of loosening.

View Article: PubMed Central - PubMed

Affiliation: Department Orthopaedics-IDi Paz, Hospital La Paz, P° Castellana 261, 28046 Madrid, Spain. edugrey@yahoo.es

ABSTRACT

Background: The preoperative bone defect and the reconstruction of the center of rotation of the hip are critical in acetabular revision surgery. Uncemented oblong cups are employed in order to manage these issues. We analyzed the clinical results and rates of revision of two different uncemented oblong cups, the reconstruction of the center of rotation of the hip, as well as the rate of radiological loosening and possible risk factors.

Materials and methods: Forty-five patients (46 hips) underwent acetabular revision surgery using two different uncemented oblong cups. We assessed the clinical results and the survival rate for revision and aseptic loosening. Intraoperative bone loss was classified according to Paprosky, and acetabular reconstruction was assessed according to Ranawat. The mean follow-up was 7.2 years (range 4-11 years).

Results: There were four re-revisions (three due to aseptic loosening); the survival rate for re-revision due to aseptic loosening was 60.1 % at seven years. The mean distance between the center of the femoral head prosthesis and the approximate center of the femoral head improved from 21.5 to 10.2 mm. Thirteen cups showed radiological loosening; the survival rate for radiological loosening at seven years was 40.54 %. A smaller postoperative horizontal distance was correlated with cup loosening.

Conclusions: Although optimal acetabular reconstruction can be achieved by using oblong uncemented cups in revision hip surgery, the clinical and radiological results are not encouraging. Excessive medialization of the cup may increase the rate of loosening.

Show MeSH
Related in: MedlinePlus