Total Hip Arthroplasty With a Monoblock Conical Stem in Dysplastic Hips: A 20-Year Follow-Up Study

Francesco La Camera ¹ , Mattia Loppini ² , Antonello Della Rocca ¹ , Vincenzo de Matteo ³ , Guido Grappiolo ¹

1. Hip Diseases and Joint Replacement Surgery Unit, Humanitas Clinical and Research Center – IRCCS, Rozzano, Milan, Italy.
2. Hip Diseases and Joint Replacement Surgery Unit, Humanitas Clinical and Research Center – IRCCS, Rozzano, Milan, Italy; Department of Biomedical Sciences, Humanitas University, Milan, Italy.
3. Section of Orthopaedic Surgery Department of Public Health, School of Medicine, “Federico II” University of Naples, Naples, Italy.

Abstract

Background: Total hip arthroplasty in patients with hip dysplasia is challenging as a result of complex anatomic deformities in the hip. The aim of the study was to evaluate the survivorship, the clinical and radiographic outcomes of cementless Wagner Cone stem in patients with dysplastic hip.

Methods: This retrospective study reports on 102 patients (135 hips) who have undergone total hip arthroplasty between 1993 and 1997. The mean age of patients was 51 years (range, 21-73). Minimum follow-up was 20 years. According to the Crowe classification, 38 hips presented dysplasia of grade I, 41 of grade II, 37 of grade III, and 19 of grade IV.

Results: Kaplan-Meier survivorship for aseptic loosening was 97% (95% confidence interval, 94.4-99.6) at 20 years. The average Harris hip score increased from 43.4 points (range, 22-51) to 86.4 points (range, 39-100) (P < .0001) and average Merle d’Aubignè score increased from 8.4 (range, 4-13) to 15 (range, 5-18) (P < .0001); at the last follow-up, average University of California at Los Angeles activity score and visual analog score were 4.53 (range, 1-9) and 1.25 (range, 0-6), respectively; 17% of heterotopic ossification and 19.2% of radiolucency lines around the stem were reported.

Conclusion: Monoblock Wagner Cone stem is a reliable option in dysplastic hip with an excellent survivorship and good clinical and radiographic outcome in the long term.

Keywords: conical stem; developmental hip dysplasia; monoblock stem; survivorship; total hip arthroplasty.

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