Long-Term Results of Medial Unicompartmental Knee Arthroplasty for Knee Avascular Necrosis

J Arthroplasty. 2019 Mar;34(3):465-468. doi: 10.1016/j.arth.2018.11.010. Epub 2018 Nov 12.


Background: Numerous series have documented short and mid-term successes with cemented, metal-backed modern unicompartmental knee arthroplasty (UKA) for avascular osteonecrosis of the knee (AVN). However, data are lacking regarding long-term implant fixation and patient function. The aim of this study is therefore to evaluate the long-term clinical outcome and implant survivorship of patients who underwent UKA for medial knee osteonecrosis (ON).

Methods: Twenty-nine consecutive UKAs performed by 2 senior surgeons (>50 UKAs a year) in 28 patients (19 women and 9 men with a mean age of 67 years) with medial unicompartmental AVN of the knee between 1989 and 2001 were retrospectively reviewed. AVN was diagnosed using X-ray, magnetic resonance imaging scan, and finally confirmed by postoperative sample analysis. The mean patient body mass index was 27 kg/m2. Etiologies were spontaneous/idiopathic AVN in 19 knees (66%) and secondary AVN in 10 knees (33%). The mean follow-up was 21 years (range 15-26).

Results: At 15 years, survivorship of the components free of revision for any cause was 92% (95% confidence interval 87-97). At latest follow-up, 26 years, survivorship of the components free of revision for any reason was 83% (95% confidence interval 74-95). No survivorship difference was found between the patients suffering from spontaneous or secondary ON of the knee (83% vs 90%, P = .6). At latest follow-up, the mean Knee Society Scoring system Knee was 89 points (range 68-100) and 83 (range 66-96) for Knee Society Scoring system Function.

Conclusion: In the longest series to date, medial UKA for treatment of AVN was associated with high survival rates and stable clinical improvement. UKA is a durable and efficient option to treat patients with unicompartmental ON of the knee.

Level of evidence: IV.

Keywords: UKA; avascular osteonecrosis; cemented metal backed; long-term results; survivorship.

MeSH terms

  • Aged
  • Aged, 80 and over
  • Arthroplasty, Replacement, Knee / methods
  • Arthroplasty, Replacement, Knee / statistics & numerical data*
  • Body Mass Index
  • Female
  • Humans
  • Knee / surgery
  • Knee Joint / surgery*
  • Male
  • Middle Aged
  • Osteonecrosis / surgery*
  • Postoperative Period
  • Radiography
  • Retrospective Studies
  • Surgeons
  • Treatment Outcome