['Besides the primary goal of functional improvement and pain reduction, the operative treatment of unicompartmental arthritis in younger patients is focused on preservation of intact bone and joint structures. The question arises whether an interpositional knee implant based on magnetic resonance imaging (MRI) data can be an alternative treatment option to the established procedures of high tibial osteotomy and unicompartmental knee arthroplasty.', 'From June 2004 to May 2008 a total of 33 patients suffering from unicompartmental knee arthritis received a patient-specific interpositional implant (31 medial and 2 lateral) within a single arm trial. The mean follow-up time was 26.6 months (range 1-48 months) and the mean age of the patients was 54.5 years (range 39-65 years). In addition to the clinical results the Western Ontario and McMaster Universities Osteoarthritis index (WOMAC) function scale and the Knee Society scores were measured. A descriptive data analysis, a variance analysis for repeated measurements and a determination of significance level were carried out.', 'The 2-4 year results showed a significant improvement in the WOMAC function scale as well as the Knee Society scores. The knee function after 2 years was comparable to the preoperative situation with an extension to flexion of 0/2/130°. The dislocation rate was 6% and the overall revision rate 21%.'] Do [ The 2-year follow-up results of a patient-specific interpositional knee implant ]?