Lack of Bone-on-Bone Arthritis Is Not a Strict Contraindication for Mobile-Bearing Unicompartmental Knee Arthroplasty

Abstract

Background: Unicompartmental knee arthroplasty (UKA) is a viable option for patients with symptomatic knee arthritis isolated to 1 compartment. Previous articles have suggested that mobile-bearing UKA should not be performed in patients without bone-on-bone arthritis. The purpose of this study was to compare the clinical outcomes and survivorship of mobile-bearing UKA in patients with severe osteoarthritis with bone-on-bone contact and patients with severe osteoarthritis but without bone-on-bone contact. Methods: We retrospectively reviewed a single surgeon’s experience with medial compartment mobile-bearing UKA in 219 patients (271 knees) who underwent the procedure between 2007 and 2015. Anteroposterior and posteroanterior radiographs were reviewed, and arthritis was graded using the International Knee Documentation Committee (IKDC) grading system. Only patients with grade D (severe arthritis) were studied. Of the patients who had grade-D arthritis, there were 81 patients (94 knees) with bone-on-bone arthritis and 82 patients (91 knees) without bone-on-bone contact. Functional outcomes were assessed using the Knee Society pain and function scores. Survivorship free of revision in these 2 groups was determined using Kaplan-Meier curves at 8 years. Results: There were no significant differences between the 2 groups in terms of age (p = 0.91), sex (p = 0.21), or body mass index (p = 0.63). At the time of the final follow-up, there was no significant difference in Knee Society pain scores (p = 0.59) or Knee Society function scores (p = 0.9) between the 2 groups. There were 5 revisions in the group with bone-on-bone contact and 2 revisions in the group without bone-on-bone contact. The survivorship free of revision at 8 years was 95% for the group with bone-on-bone contact and 98% for the group without bone-on-bone contact (p = 0.45). Conclusions: Patients with severe knee arthritis (IKDC grade D) without bone-on-bone contact had similar outcomes of mobile-bearing UKA compared with patients with bone-on-bone contact. UKA is a safe and reliable option in patients with severe osteoarthritis who do not have bone-on-bone contact on preoperative radiographs and it should therefore not be considered a contraindication for mobile-bearing UKA as long as the patient’s symptoms are severe enough to warrant surgical intervention. Level of Evidence: Prognostic Level III . See Instructions for Authors for a complete description of levels of evidence.

Unicompartmental knee replacement: controversies and technical considerations

“…The criteria for selecting patients for UKR have been well described previously and have been expanded in recent years by the Oxford group [ 2 ]. It is impossible to overstate the necessity of strictly adhering to the guidelines for using this prosthesis, with accurate patient selection being a key factor in the success of this surgical procedure.…”

“…It is impossible to overstate the necessity of strictly adhering to the guidelines for using this prosthesis, with accurate patient selection being a key factor in the success of this surgical procedure. An intact anterior cruciate ligament (ACL), bone-on-bone osteoarthrosis, and patients with a correctable deformity are among the related indications [ 2 , 3 ].…”

Bone-on-Bone Contact on Radiograph is not a Prerequisite for Successful Outcome in Fixed-Bearing Medial Unicompartmental Knee Arthroplasty—A 10-Year Follow-Up Study

“…8 There has not been any universal consensus on the indications for using fixed-bearing UKA implants based on preoperative radiographic findings and current literature only examined outcomes of fixed-bearing medial UKAs performed on patients with bone-on-bone arthritis. 9,10 This study aims to compare functional outcomes and survivorship rates between patients with varying degrees of OA to determine the relationship between the degree of OA on preoperative radiographs and clinical outcomes following fixed-bearing medial UKAs.…”