Mechanical alterations in the avascular region of the meniscus following partial meniscectomy: A cadaveric porcine longitudinal meniscal tear model

https://doi.org/10.1016/j.clinbiomech.2020.105005Get rights and content

Highlights

  • Meniscal repair effectively restored articular cartilage contact pressures.

  • Meniscectomy in avascular regions did not altered cartilage contact pressures.

  • Meniscectomy could be a viable treatment for the tears in avascular regions.

Abstract

Background

Although partial meniscectomy is a common treatment for the tears in the avascular region of the meniscus, mechanical alterations following meniscectomy are known to initiate mechanically-induced osteoarthritis. We aimed to measure the articular cartilage contact pressure distributions in the knees with surgically repaired and partially resected menisci in the avascular region.

Methods

A pneumatic loading device was developed to apply a 1000 N compressive load on the cadaveric porcine knee samples at the flexion angles of 20, 35, 50, and 65°. We simulated longitudinal meniscal tears in the avascular inner 1/3 portion and the well-vascularized middle 1/3 portion of the meniscus. Articular cartilage contact pressures for the knees with intact, torn, repaired, and resected menisci were compared.

Findings

For the tears in well-vascularized regions, meniscal repairs restored articular cartilage contact pressures to the levels in intact joints. However, partial meniscectomy significantly increases the maximum contact pressures and the average contact pressures in highly compressed areas. However, partial meniscectomy in the avascular region did not alter the maximum articular cartilage contact pressures and the average contact pressures in highly compressed areas. Stabilities in knee samples were not significantly altered following partial meniscectomy in both inner and middle regions.

Interpretation

Although repair surgeries are beneficial for the tears in well-vascularized areas because the articular cartilage contact mechanics are reconstructed, partial meniscectomy may be a viable alternative treatment for the tears in avascular regions without introducing significant mechanical alterations.

Introduction

The meniscus is a wedge-shaped structure that distributes joint loads over the entire articular cartilage surface and improves the stability of the joint movements in the knee. Tears in the meniscus, caused by traumas or age-related degenerative processes, are one of the most common type of knee injuries. Numerous studies have reported a significant relationship between meniscal tears and the development of post-injury osteoarthritis (OA) (Englund et al., 2009a, Englund et al., 2009b; Katz et al., 2013; Murphy et al., 2019b; Sharma et al., 2008). Damages in the mechanical functions of torn menisci are believed to significantly impair the weight-bearing capacities of the knee joint, which may result in an early onset of OA (Marchetti et al., 2017; Song et al., 2006, Song et al., 2014).

Partial meniscectomy has been a popular treatment for torn menisci due to its minimal invasiveness, fast and convenient surgical procedure, and short recovery periods (Fox et al., 2015). Although partial resection of the torn meniscus can effectively reduce pain, restore functions, and minimize tear progression, clinical studies have reported that meniscectomy tends to promote articular cartilage degenerations (Murphy et al., 2019b; Rockborn and Messner, 2000; Stein et al., 2010). Post-meniscectomy articular cartilage degradations may be caused by mechanical alterations in the magnitude and distribution of articular cartilage contact stresses (Bedi et al., 2010, Bedi et al., 2012; Dong et al., 2014; Lee et al., 2006; Song et al., 2006, Song et al., 2014). Meniscectomy was found to concentrate joint loadings on localized areas, which results in greater articular cartilage consolidations (Song et al., 2008). Increased cartilage deformation may lead to chronic dehydration in the extracellular matrix of the articular cartilage, which is detrimental to maintaining healthy articular cartilage structures. Thus, the use of meniscectomy treatments is limited due to the risk of mechanically-induced articular cartilage degenerations.

Recent treatments of meniscal tears include surgical repairs to maintain the native biomechanical conditions in the knee joint (Fox et al., 2015; Marchetti et al., 2017; Murphy et al., 2019a). Although meniscal repairs have been reported to significantly reduce the risk of post-surgery OA developments (Weber et al., 2018), the outcome of the surgeries depends on the healing ability of the meniscus. Because vascular supply is limited in the outer 1/3 portion of the meniscus, meniscal repairs in this well-vascularized region have been reported to be successful (Murphy et al., 2018; Noyes and Barber-Westin, 2010). However, the tears in the inner 1/3 portions of meniscus may not be healed properly due to the limited blood supply (Murphy et al., 2018; Noyes and Barber-Westin, 2010; Weber et al., 2018). Clinical studies reported that healing rates in the avascular inner 1/3 region of the meniscus were much lower than the healing rates in well-vascularized portions of the meniscus (the middle and outer 1/3 regions) (Bombelli et al., 1997; Weber et al., 2018). Repairs in the avascular inner regions might result in the need for multiple revision surgeries or cause an eventual failure in healing (Mordecai et al., 2014).

Repair surgeries are prescribed as an optimal treatment for meniscal tears. However, partial meniscectomy is still the preferred option for tears in the avascular region in spite of the risk of mechanically-induced OA (Jeong et al., 2012; Murphy et al., 2019b). Thus, the purpose of this study was to examine the risk of mechanical alterations following partial meniscal resection surgeries in the avascular inner region. Porcine cadaveric knee models with a longitudinal tear in the medial menisci were tested. We measured the articular cartilage contact pressure distributions in the knees with surgically repaired and partially resected menisci in the avascular region at various flexion angles. We then compared the magnitudes and the locations of the contact pressures in repaired and meniscectomized knees to estimate the risk of mechanically-induced articular cartilage degenerations following each treatment.

Section snippets

Sample preparation

Fourteen healthy cadaveric porcine knees were tested. The pigs weighted approximately 100 kg. We chose the porcine model due to its anatomical and functional similarities to human knees (Hennerbichler et al., 2007). Joint capsules and collateral ligaments were carefully removed while both cruciate ligaments remained intact. This was done to exclude the effect of soft tissues on articular cartilage contact mechanics. Circumferential attachments of the meniscus were removed to insert pressure

Maximum contact pressure

A representative image of the Tekscan pressure measurements in one of the tested knees is shown in Fig. 4. Variations in the maximum articular cartilage contact pressure between the knees with intact, torn, repaired, and partially resected menisci in the White-White regions were only significant at flexion angles of 20° and 35° (one-way ANOVA, p < 0.05), and no pairwise differences were found between the groups (Fig. 5a). However, variations in the maximum contact pressure for the tears in the

Discussion

Although repair surgeries are one of the common treatments for meniscal tears, partial meniscectomy has been popular for the tears in avascular regions of the meniscus because meniscal tissues in the avascular areas may not be completely healed due to the poor blood supply. However, total or partial resection of the meniscus has been shown to alter articular cartilage contact stress distributions and may initiate the onset of OA (Bae et al., 2012; Englund and Lohmander, 2006). In this study, we

Conclusions

In this study, we measured articular cartilage contact pressures using Tekscan pressure sensors to examine the mechanical alterations following partial meniscectomy in the avascular region of the meniscus because surgical outcomes of meniscal repair surgeries in the avascular regions have not been successful due to the limited healing ability. Our results revealed that partial meniscectomy in the avascular region did not statistically alter the maximum contact pressures and the average

Declaration of competing interest

The authors declare that they have no conflict of interest.

Acknowledgments

This work was supported by the National Research Foundation of Korea(NRF) grant funded by the Korea government(MEST) (NRF-2015R1C1A1A02037088).

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