The first-generation anatomical medial meniscus prosthesis led to unsatisfactory results: a first-in-human study

Abstract

Purpose The purpose of this first-in-human study was to evaluate the effect of a polycarbonate anatomical meniscus prosthesis system, including the surgical procedure, on knee pain and describe potential adverse events in patients with post-meniscectomy pain syndrome. Methods Eleven patients with post-meniscectomy pain syndrome and limited underlying cartilage damage were enrolled in the study. Five received a medial polycarbonate urethane meniscus prosthesis which was clicked onto 2 titanium screws fixated at the native horn attachments on the tibia. The KOOS score was planned to be collected at baseline and at 3, 6, 12 and 24 months following the intervention including radiographs at 6, 12 and 24 months. MRI scans were repeated after 12 and 24 months. Results The surgical technique to select an appropriately sized implant and correct positioning of the fixation screws and meniscus prosthesis onto the tibia was demonstrated to be feasible and reproducible. Inclusion stopped after 5 patients because of serious adverse device-related events. All patients reported knee joint stiffness and slight effusion in their knee at 6 months follow-up. In 3 patients the implant was removed because of implant failure and in 1 patient the implant was removed because of persistent pain and extension limitation. In none of the patients did the KOOS score improve in the first 6 months after surgery. However, in the patient who still has the implant in situ, PROMs started to improve 1 year after surgery and this improvement continued through 2 years of follow-up. The KOOS Pain, symptoms and ADL were close to the maximal 100 points. KOOS QoL and sport did improve but remained suboptimal. Conclusion This first version of the meniscus prosthesis led to impaired knee function and failed in four out of five patients. The patients where the prosthesis was removed were salvable and the PROMs returned to pre-study levels. The results in the patient where the device is still in place are promising. Level of evidence Level II.

An anatomically shaped medial meniscus prosthesis is able to partially restore the contact mechanics of the meniscectomized knee joint

“…Based on the comparison with alternative treatments and the outcomes of this study, the meniscus prosthesis system presented here is expected to relieve pain in patients who have undergone (sub‐)total medial meniscectomy. The positive results of the patient with the remaining first‐generation prosthesis in the first‐in‐human clinical investigation corroborate this hypothesis [24]. The outcomes of the clinical investigation suggest that even the stiff version of the meniscus prosthesis may eventually adapt to the geometry of the knee joint through permanent deformation after two years of continued loading.…”

“…The outcomes of the clinical investigation suggest that even the stiff version of the meniscus prosthesis may eventually adapt to the geometry of the knee joint through permanent deformation after two years of continued loading. The results indicate that the meniscus prosthesis has the potential to reduce pain in the affected knee compartment, provided that it has a good fit and is positioned correctly [24].…”

“…This resulted in a relatively rigid prosthesis, which requires a perfect fit and position due to the lack of geometrical adaptability, to conform with the femoral surface geometry which changes during flexion and extension. This configuration was evaluated during a first‐in‐human clinical investigation in five patients, who had previously undergone meniscectomy [24]. The high in‐plane stiffness of the prosthesis, in combination with the rigid fixation technique by means of screws, resulted in a deficit of knee flexion and extension and persistent pain in all patients.…”

“…Four out of five prostheses were explanted, of which three were broken. It was concluded that, due to the rigidity of the prosthesis and its fixation, the compressive loads were transferred entirely through the prosthesis and not through the direct tibiofemoral contact [24]. This lack of load sharing increased the compressive and circumferential stresses in the prosthesis and ultimately resulted in structural failure of the prosthesis.…”

Meniscal Allograft versus Synthetic Graft in Treatment Outcomes of Meniscus Repair: A Mini-review and Meta-analysis

“…14 Importantly, the shortage of meniscus allografts from cadavers may be a challenging issue to meet the increasing requirement of MAT for an aging society around the world. 15 Recently, as an alternative to a meniscal allograft, synthetic meniscal substitutes with custom-sized, biocompatible, and porous materials have been serving as a scaffold to restore meniscal function. Encouragingly, there are three commercial products approved by the local regulatory body for clinical use.…”