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Influence of Severity and Duration of Anterior Knee Pain on Quadriceps Function and Self-Reported Function
1Athletic Training Laboratory, Department of Sports Medicine, Kyung Hee University, Yongin, Republic of Korea.
Context:
Little is known about how the combination of pain severity and duration affects quadriceps function and self-reported function in patients with anterior knee pain (AKP).
Objective:
To examine how severity (low [≤3 of 10] versus high [>3 of 10]) and duration (short [<2 years] versus long [>2 years]) of AKP affect quadriceps function and self-reported function.
Design:
Cross-sectional study.
Setting:
Laboratory.
Patients Or Other Participants:
Sixty patients with AKP (mean pain severity = 4 of 10 on the numeric pain rating scale, mean pain duration = 38 months) and 48 healthy control individuals. Patients with AKP were categorized into 3 subdivisions based on pain: (1) severity (low versus high); (2) duration (short versus long); and (3) severity and duration (low and short versus low and long versus high and short versus high and long).
Main Outcome Measure(S):
Quadriceps maximal (maximal voluntary isometric contraction) and explosive (rate of torque development) strength, activation (central activation ratio), and endurance (average peak torque) and self-reported function (Lower Extremity Functional Scale score).
Results:
Compared with the healthy control group, (1) all AKP subgroups showed less quadriceps maximal strength (P < .005, d ≥ 0.78) and activation (P < .02, d ≥ 0.85), except for the AKP subgroup with low severity and short duration of pain (P > .32); (2) AKP subgroups with either high severity or long duration of pain showed less quadriceps explosive strength (P < .007, d ≥ 0.74) and endurance (P < .003, d ≥ 0.79), but when severity and duration were combined, only the AKP subgroup with high severity and long duration of pain showed less quadriceps explosive strength (P = .006, d = 1.09) and endurance (P = .0004, d = 1.21); and (3) all AKP subgroups showed less self-reported function (P < .0001, d ≥ 3.44).
Conclusions:
Clinicians should be aware of the combined effect of severity and duration of pain and incorporate both factors into clinical practice when rehabilitating patients with AKP.
