Muscle Endurance Performance of Quadriceps and Hamstrings, and Functional Ability Before and after Arthroscopic Meniscal Surgery: a Case Controlled Inter-limb Comparison
The objective of this study was to investigate muscle performance of the quadriceps and hamstrings muscles, as well as lower limb function in participants with meniscal lesions that required partial meniscectomy. It was of particular interest to assess whether there were significant deficits in an inter-limb assessment of muscle strength and endurance, as well as performance in a repetitive hop test, one week prior to surgery and six weeks after partial meniscectomy. Additionally, the relationship between performance measures (isokinetic and hopping) and perceived function (questionnaires) was examined.
An inter-limb comparison of isokinetic knee flexion and extension muscle strength and endurance, and a functional hop endurance was implemented on 21 participants with meniscal injury before and after partial meniscectomy. Testing was performed one week prior to surgery, and again six weeks after surgery. For the control group, 22 healthy matched participants performed the same testing protocols on two occasions, six weeks apart.
Surgery is often required for tears to the meniscus of the knee. The minimal nature of modern surgical intervention for meniscal injuries has led to a belief that exercise rehabilitation after surgery is often not needed. Rehabilitation, when undertaken, has been focused upon strengthening. Yet many activities require muscular endurance capability. Without sufficient endurance, fatigue can lead to added stress upon joint structures, leading to further inflammation and potentially long-term damage in the form of osteoarthritis.
Forty-six participants aged between 24 and 57 years were recruited. Three participants were excluded as they had post-operative complications. Therefore, the total sample size for the current study was 21 participants in the partial meniscectomy group and 22 participants in the control group.
A Biodex isokinetic dynamometer was used to assess quadriceps and hamstrings strength (peak torque) and endurance performance (peak torque over 30 consecutive maximum effort repetitions). A functional performance endurance test was performed on a force plate, and assessed changes in flight time over 30 consecutive hops, four seconds apart. Self-reported function was measured using the Lower Limb Task Questionnaire (LLTQ) and Knee Injury and Osteoarthritis Outcome Score (KOOS). All assessment protocols where performed at two testing session; one week prior to surgery and six weeks after partial meniscectomy. Analysis of Variance (ANOVA) and Pearson correlation coefficients were utilised for the statistical analysis with an alpha level set to 0.05.
The partial meniscectomy group had significant (p<0.05) quadriceps and hamstrings deficits and functional hop deficits on the injured limb when compared to the non-injured limb and control participants. These differences across limbs ranged between six and eighteen percent. Specifically, in measures of endurance, there were significant differences (p<0.05) across limbs pre-operatively in the quadriceps, hamstrings, and functional hop test (six to 10 percent deficits), and these were also observed post-operatively in the quadriceps and functional hop test (seven to 15 percent deficits). The decrement of peak torque in the quadriceps and flight time in the maximal effort repeated hop test were at a lesser rate compared to the non-injured limb and the control group limbs (p<0.05).
There were clinically significant (greater than 10 points) improvements in self-reported function between pre- and post-operative scores. This was observed in all subscales of the KOOS, and the recreational section of the LLTQ. Despite these improvements, participants had significantly lower functional scores (p<0.05) compared to control subjects in all measures of self-reported function post-operatively. There was a significant relationship between LLTQ RA and the repeated hop task where lower scores moderately correlated (r= -0.51) with deficits across limbs in flight time during the highest three hops of this task. The remaining correlations between self-reported function and performance tasks were not significant (p>0.05).
In respect of endurance of quadriceps and hamstring muscles, the findings suggest that endurance across the 30 repetitions is satisfactory for return to recreational low intensity activities. However, deficits of greater than 10 percent were observed across limbs in quadriceps muscle performance pre- and post- surgery, and these should be addressed by further rehabilitation.
The across limbs percent deficits in the quadriceps and hamstrings muscles strength and endurance measures were not significantly related to perceived function. This was thought to be related to the differences in complexity of the tasks involved. There was a significant correlation between function as measured by the recreational section of the LLTQ and hop performance task, and this could be advantageous in clinics where performance testing cannot take place.
Overall the results suggest that increased formal rehabilitation is needed for individuals who have had a partial meniscectomy. The current belief in the orthopaedic community that return to full sport at six weeks post-operation is appropriate therefore needs to be reassessed.