Patient-Specific Implants for Focal Cartilage Lesions in The Knee: Implant Survivorship Analysis up to Seven Years Post-Implantation

Abstract

In the quest for increased surgical precision and improved joint kinematics, Computer-Assisted Orthopedic Surgery (CAOS) shows promising results for both total and partial joint replacement. In the knee, computer-assisted joint design can now be applied to the treatment of younger patients suffering pain and restriction of activity due to focal defects in their femoral articular cartilage. By taking MRI scans of the affected knee and digitally segmenting these scans, we can identify and map focal defects in cartilage and bone. Metallic implants matched to the defect can be fabricated, and guide instrumentation to ensure proper implant alignment and depth of recession in the surrounding cartilage can be designed from segmented MRI scans. Beginning in 2012, a series of 682 patient-specific implants were designed based on MRI analysis of femoral cartilage focal defects, and implanted in 612 knees. A Kaplan-Meier analysis found a cumulative survivorship of 96% at 7-year follow-up from the first implantation. Fourteen (2.3%) of these implants required revision due to disease progression, incorrect implant positioning, and inadequate lesion coverage at the time of surgery. These survivorship data compare favorably with all other modes of treatment for femoral focal cartilage lesions and support the use of patient-specific implants designed from segmented MRI scans in these cases.

Eighty Percent Survival of Resurfacing Implants in the Knee After 10 Years: A Nationwide Cohort Study on 379 Procedures from the Danish Knee Arthroplasty Registry

“…24 In a 682-patient study on the Episealer implant, Ryd et al . 34 found a 96% survival after 7 years. The authors concluded that most of the 14 revisions in the study were caused by improper patient selection 34 .…”

2‐year results of middle‐aged patients with two‐compartment cartilage lesions in one knee treated with two patient specific metal implants

“…Another comprehensive multicenter study published by Ryd et al tracked 612 patients treated with 682 implants, with a follow-up of up to seven years. Fourteen patients (2.3%) had to be revised after seven years due to disease progression, incorrect implant positioning, and inadequate lesion coverage at the time of surgery [ 21 ].…”

MR-Imaging in Osteoarthritis: Current Standard of Practice and Future Outlook

“…The acquisition of 3D data sets with isotropic voxels enables the radiologist to perform multiplanar reformation (MPR) of the images, allowing the reconstruction of any desired angulation. Volumetric analysis may be performed in order to assess cartilage defects for individualized orthopedic treatment [51]. Sequences used for this purpose include Double-Echo-Steady-State (DESS), SPoiled GRadient Echo (SPGR), and Sampling Perfection with Application optimized Contrasts using different flip angle Evolutions (SPACE)-sequences.…”