Long term follow up of 257 consecutive cementless Oxford medial compartment knee arthroplasties at a non-designer centre.

Aims: This study aimed to review the survivorship, indication for revision and patient reported outcomes for 257 consecutive Oxford cementless unicompartmental knee arthroplasties (OUKA's) in 238 patients at 12-14 years post-operatively.

Methods: Patients underwent surgery between April 2008 and October 2010 by two non-design surgeons including their learning curve. The 5-year clinical and radiological outcomes have already been reported. Oxford knee scores (OKS) were recorded at 1, 5 and 12-14 years with delayed review a result of the COVID-19 pandemic. Revision indication and imaging were reviewed.

Results: Revision was required in 28 OUKA's (10.9%) with a 10-year cumulative survival of 93.0%, reducing to 78.8% at 14 years. 59 patients had died prior to this review and 24 were not contactable. Those not contactable had electronic records reviewed to ensure they did not have a revision elsewhere. Half of the revisions were for progression of lateral compartment arthritis (14/28). Four of 6 cases with a full revision for polyethylene wear may have benefited from a bearing exchange instead. OKSs in non-revised patients were good (median score 38, IQR 30-44) with no significant deterioration noted from 5 to 12-14 years.

Conclusions: Cementless OUKA in this series had a long-term survival rate comparable to other OUKA's outside of the designer centre. OKSs remain good for those patients not revised. Progression of lateral compartment arthritis was the primary reason for revision with no revisions for component loosening or bearing spinout. Ideally UKA patients who experience problems should be under the care of revisions surgeons who perform UKA. Improving patient selection and understanding of the pathophysiology of lateral disease progression, remain crucial to improve the long-term survivorship of OUKA.