Prospective Single-Arm, Multi-Center Trial of a Patient-Specific Interpositional Knee Implant: Early Clinical Results

Abstract

Background:The treatment of unicompartmental arthritis in younger patients is challenging. The aim of this study is to report final safety and efficacy analysis results for the iForma patient–specific interpositional device, which is designed for the treatment of isolated medial or lateral compartment arthritis of the knee.Methods:From June 2005 to June 2008 78 subjects (42 men, 36 women) received an iForma implant. The mean age was 53 years, the mean Body Mass Index 29.0. We surveyed the WOMAC scores, the visual analog pain scale and the Knee Society Scores.Results:The mean follow up was 16.4 months. The mean WOMAC knee scores increased from 48.3 before surgery to 71.3 after 24 months. A reduction in pain was achieved for all five pain measures using a standard visual analog scale (VAS). Knee Society Knee Score improved from 39.2 before to 61.9 24 month after surgery. The Knee Society Function Scores improved form preoperative 64.5 to 82.5 2 years postoperative. The preoperative range of motion could be restored. The overall revision rate was 24%. 15 implants were removed early, 4 knees were revised without implant removal.Conclusion:Within narrow indication of patients with unicompartmental disease, the iForma device can provide improvement in knee function and reduction in pain, however, with a significant higher risk of early revision compared to traditional arthroplasty. Respecting this limitation it may be an alternative option for arthritic patients with unicompartmental disease who have contraindications to High Tibial Osteotomy or are too young for knee replacement; the iForma device further has the distinct advantage of time and cost saving compared to those procedures.

Quantification of in vitro wear of a synthetic meniscus implant using gravimetric and micro-CT measurements

“…The main anticipated complications of such device include implant dislocation, and increased fatigue or wear if the implant is pressed into a location/ orientation in which it is not congruent with the other surfaces. Dislocation has been reported frequently for metal interpositional spacers, and it seems to be one of the main reason they are no longer available for commercial use (Bailie et al, 2007;Koeck et al, 2011). While the exact passive motion patterns of the PCU implant were not quantified in the current study, preliminary clinical data suggests that the implant moves between approximately 10 mm anteriorly and 7 mm posteriorly in-vivo, with some rotation (de Coninck et al, 2014).…”

Unicompartmental knee replacement provides early clinical and functional improvement stabilizing over time

“…Felts [12] and Parratte [19] demonstrated that polyethylene wear remains a major problem affecting the survival of UKR in younger active population. Recently, for those patients who have passed the age for biological cartilage repair, but are considered too young for traditional, more invasive joint replacement, modern patient‐specific interpositional devices may be a good solution [15].…”

Insufficient evidence to confirm benefits of custom partial knee arthroplasty: a systematic review

“…The electronic search returned 2766 articles, of which 390 were duplicates and 2346 excluded after reading their titles and abstracts. Of the remaining 30 articles, 13 were not relevant [6, 11, 17, 19, 21, 23, 26, 28, 29, 37, 39, 40, 43], one was a review [41], and one an in‐vitro study [44], which were all excluded after reading their full texts. This left 15 articles that were eligible for data extraction, of which six were on custom UKA [2, 13, 16, 22, 27, 45], six on custom BKA [3, 7, 33, 36, 42, 49], and three on custom PFA [9, 12, 38] (Fig.…”