Unicompartmental knee arthroplasty in obese patients, poorer survivorship at 15 years

Hong Jing Lee; Sheng Xu; Ming Han Lincoln Liow; Hee Nee Pang; Darren Keng-Jin Tay; Seng Jin Yeo; Ngai Nung Lo; Jerry Yongqiang Chen

doi:10.1016/j.jor.2024.04.001

Unicompartmental knee arthroplasty in obese patients, poorer survivorship at 15 years

J Orthop. 2024 Apr 2:53:156-162. doi: 10.1016/j.jor.2024.04.001. eCollection 2024 Jul.

Authors

Hong Jing Lee¹, Sheng Xu², Ming Han Lincoln Liow², Hee Nee Pang², Darren Keng-Jin Tay², Seng Jin Yeo², Ngai Nung Lo², Jerry Yongqiang Chen²

Affiliations

¹ Lee Kong Chian School of Medicine, Nanyang Technological University, Headquarters & Clinical Sciences Building 11, Mandalay Road, Singapore, 308232, Singapore.
² Department of Orthopaedic Surgery, Singapore General Hospital, 20 College Road, Academia Level 4, Singapore, 169856, Singapore.

PMID: 38601892
PMCID: PMC11002850 (available on 2025-07-01)
DOI: 10.1016/j.jor.2024.04.001

Abstract

Introduction: The preclusion of obese patients from unicompartmental knee arthroplasty (UKA) has increasingly been challenged. This study aimed to evaluate the impact of Body Mass Index (BMI) on UKA at 15-year follow-up.

Materials and methods: 169 unilateral UKA patients from 2003 to 2007 were followed-up prospectively for at least 15 years. 70 patients were left for analysis after accounting for patient demise, revision surgery and loss to follow-up. 48 of these patients (69%) were in the Control group (BMI <30 kg/m²) and 22 (31%) were in the Obese group (BMI ≥30 kg/m²). Patients were assessed before and after operation using the Knee Society Function Score (KSFS), Knee Society Knee Score (KSKS), Oxford Knee Score (OKS), and Physical (PCS) and Mental (MCS) component of the Short Form 12. Survivorship analysis was also performed.

Results: Obese patients went through UKA at an earlier age than the non-obese patients (54.7 ± 4.7 years compared to 59.9 ± 7.8 years, p = 0.005). At 2, 10, and 15-year follow-up, both groups achieved clinically significant improvements in outcomes. There was no significant association found between obesity and outcome using multiple linear regression. While propensity matching found PCS improvement at 2 years to be greater in obese patients, no significant association between obesity and 15-year outcome was found. All 13 patients who required revision, underwent total knee arthroplasty (TKA). The overall 15-year survivorship was 74.2% within the obese group and 92.4% within the control group.

Conclusion: Compared to non-obese patients, obese patients had poorer 15-year survivorship with greater odds of requiring revision surgery. However, assuming implant survival, obese patients can expect a non-inferior outcome relative to their non-obese counterparts in all patient reported outcome measures 15 years after surgery.

Keywords: Functional outcome; Obesity; Quality of life; Survivorship; Unicompartmental knee arthroplasty.