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Orthopaedic Proceedings
Vol. 105-B, Issue SUPP_9 | Pages 14 - 14
17 Apr 2023
Bartolo M Newman S Dandridge O Provaggi E Accardi M Dini D Amis A
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No proven long-term joint-preserving treatment options exist for patients with irreparable meniscal damage. This study aimed to assess gait kinematics and contact pressures of novel fibre-matrix reinforced polyvinyl alcohol-polyethylene glycol (PVA-PEG) hydrogel meniscus implanted ovine stifle joints against intact stifles in a gait simulator.

The gait simulator controlled femoral flexion-extension and applied a 980N axial contact force to the distal end of the tibia, whose movement was guided by the joint natural ligaments (Bartolo; ORS 2021;p1657- LB). Five right stifle joints from sheep aged >2 years were implanted with a PVA-PEG total medial meniscus replacement, fixed to the tibia via transosseous tunnels and interference screws. Implanted stifle joint contact pressures and kinematics in the simulator were recorded and compared to the intact group. Contact pressures on the medial and lateral condyles were measured at 55° flexion using Fujifilm Prescale Low Pressure film inserted under the menisci. 3D kinematics were measured across two 30 second captures using the Optotrak Certus motion-tracking system (Northern Digital Inc.).

Medial peak pressures were not significantly different between the implanted and intact groups (p>0.4), while lateral peak pressures were significantly higher in the implanted group (p<0.01). Implanted stifle joint kinematics in the simulator did not differ significantly from the intact baseline (p>0.01), except for in distraction-compression (p<0.01).

Our findings show that the fibre-matrix reinforced PVA-PEG hydrogel meniscal replacement restored the medial peak contact pressures. Similar to published literature (Fischenich; ABE 2018;46(11):1–12), the lateral peak pressures in the implanted group were higher than the intact. Joint kinematics were similar across groups, with slightly increased internal-external rotation in the implanted group. These findings highlight the effectiveness of the proposed approach and motivate future work on the development of a total meniscal replacement.


Bone & Joint Research
Vol. 6, Issue 8 | Pages 522 - 529
1 Aug 2017
Ali AM Newman SDS Hooper PA Davies CM Cobb JP

Objectives

Unicompartmental knee arthroplasty (UKA) is a demanding procedure, with tibial component subsidence or pain from high tibial strain being potential causes of revision. The optimal position in terms of load transfer has not been documented for lateral UKA. Our aim was to determine the effect of tibial component position on proximal tibial strain.

Methods

A total of 16 composite tibias were implanted with an Oxford Domed Lateral Partial Knee implant using cutting guides to define tibial slope and resection depth. Four implant positions were assessed: standard (5° posterior slope); 10° posterior slope; 5° reverse tibial slope; and 4 mm increased tibial resection. Using an electrodynamic axial-torsional materials testing machine (Instron 5565), a compressive load of 1.5 kN was applied at 60 N/s on a meniscal bearing via a matching femoral component. Tibial strain beneath the implant was measured using a calibrated Digital Image Correlation system.