Hip and knee weakness and ankle dorsiflexion restriction in individuals following lateral patellar dislocation: A case-control study

OBJECTIVE: To explore the relationship between ankle dorsiflexion range of motion (ROM) and hip and knee muscle strength between patients with a history of patellar dislocation (PD) to healthy controls. DESIGN: Case-control study. SETTING: Orthopedical specialty outpatient clinic at a tertiary hospital. PARTICIPANTS: Eighty-eight individuals were recruited; 44 individuals aged 16 years or older, of both sexes, with a history of at least one episode of atraumatic unilateral or bilateral PD requiring emergency care (14 men; 30 women; mean age 20 years) and 44 healthy (control) individuals (11 men; 33 women; mean age 21 years) matched for age, weight, and height to PD cases. INTERVENTION: Assessment of hip and knee strength and ankle dorsiflexion ROM. OUTCOME MEASURES: Ankle dorsiflexion ROM was assessed through the lunge test with a goniometer. Hip and knee muscle strength was evaluated through isometric hand-held dynamometry. Differences between healthy and control individuals were assessed using Student t Tests and Mann-Whitney U Test. RESULTS: Patellar dislocation individuals presented with a reduced ankle dorsiflexion ROM [mean difference (MD): 9 degrees; effect size (ES): 1.39; P < 0.001] and generalized hip and knee weakness (MD range: 4.74 kgf to 31.4 kgf; ES range: 0.52-2.35; P < 0.05) compared with healthy subjects. CONCLUSION: Individuals with a history of PD have reduced ankle dorsiflexion ROM and hip and knee muscle strength compared with healthy controls.