Nicolas Martinez-Carranza

Full-depth cartilage lesions do not heal spontaneously and may progress to osteoarthritis (OA). Treatment for these lesions is warranted when symptomatic. At younger age, biological treatment remains the gold standard, but treatment in the middle-aged patient remains a clinical challenge and focal metal implants have been proposed. We aim to present the subjective outcome at 2 years and the risk of reoperation for any reason at midterm after surgery with a novel customized implant for focal femoral chondral lesions in the knee. In a prospective cohort study, 30 patients were included between January 2013 and December 2017 at 9 different clinics in Sweden. The primary outcome was subjective outcome measurements (Visual Analogue Scale [VAS], EuroQoL [EQ5D], Knee injury and Osteoarthritis Outcome Score [KOOS]) at a minimum of 2 years. The secondary outcome was reoperations for any reason during the follow-up period until December 2019 (mean of 55 months) studied retrospectively by analyzing medical records. The VAS, EQ5D, and all the KOOS subscales showed significant improvements from preoperatively to the 2-year follow-up. The VAS showed the greatest improvement at the early (3 months) postoperative stage (P < 0.001). Five (7%) patients underwent reoperations and one of these was revised to hemiarthroplasty due to OA progression. No implant loosening was detected in any of the cases. This customized resurfacing metal implant showed good safety and patient satisfaction. The risk of OA progression and implant loosening is low. Subjective function and pain improved significantly.

Full-depth cartilage lesions do not heal and the long-term clinical outcome is uncertain. In the symptomatic middle-aged (35-60 years) patient, treatment with metal implants has been proposed. However, the cartilage health surrounding these implants has not been thoroughly studied. Our objective was to evaluate the health of cartilage opposing and adjacent to metal resurfacing implants. The medial femoral condyle was operated in 9 sheep bilaterally. A metallic resurfacing metallic implant was immediately inserted into an artificially created 7.5 mm defect while on the contralateral knee the defect was left untreated. Euthanasia was performed at 6 months. Six animals, of similar age and study duration, from a previous study were used for comparison in the evaluation of cartilage health adjacent to the implant. Cartilage damage to joint surfaces within the knee, cartilage repair of the defect, and cartilage adjacent to the implant was evaluated macroscopically and microscopically. Six animals available for evaluation of cartilage health within the knee showed a varying degree of cartilage damage with no statistical difference between defects treated with implants or left untreated (P = 0.51; 95% CI −3.7 to 6.5). The cartilage adjacent to the implant (score 0-14; where 14 indicates no damage) remained healthy in these 6 animals showing promising results (averaged 10.5; range 9-11.5, SD 0.95). Cartilage defects did not heal in any case. Treatment of a critical size focal lesion with a metal implant is a viable alternative treatment.

Unicompartmental knee arthroplasty (UKA) is an established method of treating isolated gonartrosis. Modern techniques such as computer-assisted surgery (CAS) and minimally invasive surgery (MIS) are attractive complementary methods to UKA. However, the positioning of the components remains a concern. Thus, we performed a prospective study to assess whether there was deviation between the navigated implant position and the final implant position. We performed UKA with MIS and CAS in 13 patients. By comparing intraoperative navigation data with postoperative computed tomography (CT) measurements, we calculated the deviation between the computer-assisted implant position and the final 3-D implant position of the femoral and tibial components. The computer-assisted placement of the femoral and tibial component showed adequate position and consistent results regarding flexion-extension and varus-valgus. However, regarding rotation there was a large variation and 6 of 10 patients were outside the target range for both the femoral component and the tibial component. Difficulties in assessing anatomical landmarks with the CAS in combination with MIS might be a reason for the poor rotational alignment of the components.