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Orthopaedic Proceedings
Vol. 100-B, Issue SUPP_3 | Pages 43 - 43
1 Apr 2018
Seitz A Lippacher S Natsha A Reichel H Ignatius A Dürselen L Dornacher D
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Introduction

The medial patellofemoral ligament (MPFL) is the main stabilizer of the patella and therefore mostly reconstructed in the surgical correction of patellofemoral dislocation. Various biomechanical and clinical studies have been conducted on MPFL reconstruction, while the patellofemoral contact pressure (PFCP) which is indicated as one of the predictors of retropatellar osteoarthritis was neglected. Therefore, the aim of this study was to investigate how different MPFL reconstruction approaches affect PFCP.

Material & Methods

After radiographic examination and preparation six human cadaveric knee joints (52.1 ± 8.4yrs) were placed in a 6-DOF knee simulator. Three flexion-extension cycles (0–90°) were applied, while the extensor muscles (175N) and an axial joint load (200N) were simulated. PFCP was measured in knee flexion of 0°, 30° and 90° using a calibrated pressure measurement system (K-Scan, Tekscan Inc., USA). The following MPFL conditions were examined: native (Pnat), anatomical reconstruction (Pa), proximal and distal patellar single-bundle reconstruction (Pp, Pd), proximal and ventral femoral reconstruction (Fp, Fv). The cohesive gracillis graft of each knee was used for MPFL reconstruction. Further, the effect of three different graft pre-tensioning levels (2N, 10N, 20N) on the PFCP were compared. Nonparametric statistical analysis was performed using SPSS (IBM Inc., USA).


Orthopaedic Proceedings
Vol. 100-B, Issue SUPP_3 | Pages 44 - 44
1 Apr 2018
Warnecke D Balko J Schild NB Wang P Bieger R Ignatius A Mizaikoff B Reichel H Dürselen L
Full Access

Introduction

With processing age, meniscus degeneration occurs which is often associated with osteoarthritis. Existing data about the influence of degeneration on the biomechanical properties of the meniscus are still contradictory, or completely unknown regarding the hydraulic permeability. Thus, the aim of this study was to characterise the biomechanical properties and structural composition of the meniscal tissue depending on its degree of degeneration.

Methods

Menisci of 24 TKR-patients (≈67.1 yrs.) were harvested and the degeneration of each region (pars anterior PA, pars intermedia PI, pars posterior PP) classified according to Pauli et al. For biomechanical characterisation, confined compression tests (20% strain; velocity: 3%h0/min, relaxation time: 1h) to determine equilibrium modulus (HA) and hydraulic permeability (k) and tensile tests (velocity: 5%l0/min) to determine the tensile modulus were performed. Therefore, cylindrical (Ø= 4.6mm, initial height h0≈ 2.3mm) and dumbbell-shaped (3.5mm × 1.4mm × 3.5mm) samples were punched out of each region and flattened to achieve parallel surfaces. Additionally, collagen and proteoglycan (PG) content were analysed by calculating the area-under-curve of their specific wavelength ranges (1293–1356cm−1 and 980–1120cm−1, respectively) using infrared (IR) spectroscopy. To identify differences regarding the meniscus regions or its degeneration, a statistically mixed model was used.