Elsevier

The Knee

Volume 22, Issue 6, December 2015, Pages 506-509
The Knee

Forward lunge knee biomechanics before and after partial meniscectomy

https://doi.org/10.1016/j.knee.2015.03.005Get rights and content

Highlights

  • 13% reduction in peak knee flexion moment during forward lunge in APM leg compared to contralateral leg, pre –post surgery

  • Altered knee biomechanics in the recently operated knee may reflect a protective strategy to limit excessive loading

  • However, without sham surgery, our findings cannot be conclusively attributed to the effect of partial meniscectomy

Abstract

Background

Patients following meniscectomy are at increased risk of developing knee osteoarthritis in the tibiofemoral compartment and at the patellofemoral joint. As osteoarthritis is widely considered a mechanical disease, it is important to understand the potential effect of arthroscopic partial meniscectomy (APM) on knee joint mechanics. The purpose of this study was to evaluate changes in knee joint biomechanics during a forward lunge in patients with a suspected degenerative meniscal tear from before to three months after APM.

Methods

Twenty-two patients (35–55 years old) with a suspected degenerative medial meniscal tear participated in this study. Three dimensional knee biomechanics were assessed on the injured and contralateral leg before and three months after APM. The visual analogue scale was used to assess knee pain and the Knee Injury Osteoarthritis Outcome Score was used to assess sport/recreation function and knee-related confidence before and after APM.

Results

The external peak knee flexion moment reduced in the APM leg compared to the contralateral leg (mean difference (95% CI)) − 1.08 (− 1.80 to − 0.35) (Nm/(BW × HT)%), p = 0.004. Peak knee flexion angle also reduced in the APM leg compared to the contralateral leg − 3.94 (− 6.27 to − 1.60) degrees, p = 0.001. There was no change in knee pain between the APM leg and contralateral leg (p = 0.118). Self-reported sport/recreation function improved (p = 0.004).

Conclusions

Although patients self-reported less difficulty during strenuous tasks following APM, patients used less knee flexion, a strategy that may limit excessive patellar loads during forward lunge in the recently operated leg.

Introduction

Osteoarthritis is a common disease that is considered by the World Health Organisation as one of the ten leading causes of disease burden in high-income countries [1]. The knee joint is the most commonly affected lower limb joint [2]. A meniscal tear is a potent risk factor to develop knee osteoarthritis [3] and both the patellofemoral and medial tibiofemoral compartments are commonly affected by osteoarthritis following meniscectomy [4]. Degenerative tears in middle-aged adults are associated with greater risk of knee osteoarthritis than traumatic meniscal tears in younger individuals [3]. Following the removal of meniscus tissue, studies have reported a decrease in articulating contact area and an increase in contact stress [5], [6]. As knee osteoarthritis is considered at least in part, a mechanically driven disease where higher abnormally distributed forces are thought to play a role [7], it is important to discern the effect of arthroscopic partial meniscectomy (APM) on knee joint biomechanics.

The forward lunge is a challenging, functional exercise, which couples eccentric contractions and concentric contractions (also known as stretch-shortening cycle). This is pertinent as eccentric contractions typically precede concentric contractions, in the majority of daily living activities (e.g. stepping, walking) [8]. The forward lunge is also commonly used in rehabilitation programmes to improve physical function and knee muscle strength. Self-reported difficulty with strenuous tasks and knee muscle weakness has been described in people with degenerative meniscal tears pre-operatively [9] and within three months post-operatively [10], [11]. Understanding the effect of a meniscal tear and subsequent APM on knee biomechanics during a task commonly prescribed as a rehabilitation exercise to improve muscle strength and physical function is warranted.

Studies investigating the squat and forward lunge have reported increased patellar contact force and stress with increased knee flexion angle [12], [13] and medial tibiofemoral joint contact force is influenced by the external knee flexion moment during gait [14]. Furthermore, a higher external knee adduction moment during gait relates to knee pain onset [15] and disease progression in people with established knee osteoarthritis [16], [17]. Aberrant knee mechanics have been reported before and after APM [18], albeit inconsistently [19]. In particular, the knee flexion moment is reportedly reduced compared to healthy controls during gait before and six months after APM [18]. However, these few studies are limited by the lack of discrete measures and heterogeneous samples. As such, it remains largely unknown if altered knee joint mechanics are present pre-operatively, and importantly if these measures alter as a potential consequence of APM in middle-aged individuals with degenerative meniscal tears at high risk of knee osteoarthritis.

The aim of this exploratory study was to compare changes in knee joint biomechanics from before to after APM between the injured and contralateral leg during a forward lunge. We hypothesized that knee joint biomechanics would alter in the injured leg compared to the contralateral leg as a potential result of APM.

Section snippets

Patients

Individuals with a medial degenerative meniscal tear eligible for APM were recruited from Odense University Hospital, Odense, Denmark and Lillebaelt Hospital, Kolding, Denmark and Orthopedic Clinic Fyn, Odense, Denmark. Patients were considered to have a degenerative meniscal tear based on age (35–55 years) and how their knee pain developed. Patients were asked ‘how did the knee pain/problems for which you are now having surgery develop?’ and provided with the following options: a) the

Results

At surgery, it was confirmed that all patients had a medial meniscal tear and no concomitant ACL, PCL or lateral meniscus damage, thus complying with eligibility criteria. The majority of patients (91%) had a medial tear that involved the posterior horn resected by 0–25% (Table 1). Patients were predominantly male and slightly overweight according to World Health Organisation standards [26] (Table 1). Before APM, the peak knee flexion moment was lower in the injured leg compared to the

Discussion

The forward lunge is a commonly prescribed exercise to improve physical function and knee muscle weakness following APM. In this study, patients adapted an altered forward lunge movement strategy as a potential consequence of APM. Our findings show a 13% reduction in the peak knee flexion moment and approximately four degrees reduction in peak knee flexion angle during the forward lunge in the APM leg compared to the contralateral leg.

Our hypothesis that the APM leg would display altered knee

Conclusions

The forward lunge is commonly used in rehabilitation to improve physical function and knee muscle weakness. Despite patients reporting improved function during strenuous tasks after APM, it appears that patients continue to use less knee flexion during the forward lunge that may reflect a protective strategy to limit excessive knee loads in the recently operated leg.

Conflict of interest

All authors declare that they have no conflict of interest in the authorship or publication of this contribution.

Acknowledgements

This study is supported by grants from The Danish Council for Independent Research|Medical Sciences (#12-125457) and IMK Almene Fond. We would like to thank the patients for their participation in the study. Also we would like to acknowledge the Department of Orthopedics and Traumatology, Odense University Hospital, Odense and Svendborg, Department of Orthopedics, Lillebaelt Hospital, Kolding (Nis Nissen), MD Troels Laulund and project nurse Annie Gam-Pedersen for their help. MH was supported

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