Long-term Outcomes of Surgically Treated Congenital Dislocation of the Knee.

ABSTRACT

BACKGROUND: Congenital dislocation of the knee (CDK) may be idiopathic or associated with another condition, such as Larsen syndrome or arthrogryposis. Surgical reduction of type-3 dislocation may require quadricepsplasty (QP) or femoral diaphyseal shortening (FS). Because it is unknown which treatment is more effective, we evaluated long-term outcomes using patient-reported questionnaires and gait analysis, comparing results by surgery type and underlying diagnosis. METHODS: Twelve patients (mean age, 19 mo) were treated surgically for CDK from 1985 to 2015 and studied 9 to 30 years postoperatively. Three participants had idiopathic CDK, 5 had Larsen syndrome, and 4 had arthrogryposis. Eleven knees underwent QP and 7 underwent FS. Participants were evaluated in our movement science laboratory and completed patient-reported outcome questionnaires. Data were compared with healthy, age-matched control values at the same visit. RESULTS: Surgically treated knees had less flexion during swing ( P <0.01), less overall motion ( P <0.01), greater coronal instability ( P <0.04), and slower gait ( P <0.01) compared with controls. QP knees had more instability in midstance ( P =0.03) and less flexion during gait compared with FS knees, less sagittal power generation than controls ( P <0.01), and trended toward lower scores on Knee Injury and Osteoarthritis Outcome and Lysholm Knee Questionnaires than FS patients did. The idiopathic group had the gait most similar to that of controls, followed by the Larsen syndrome group and then the arthrogryposis group. The idiopathic group also had a better UCLA Activity Score ( P =0.03) than the arthrogryposis group did. CONCLUSIONS: Surgical treatment of type-3 CDK will not likely restore normal knee function, suggesting teratologic joint abnormality. In this small series, FS produced better gait mechanics and patient-reported outcomes compared with QP. Not surprisingly, patients with idiopathic CDK had better outcomes than those with a syndromic diagnosis, likely related to having only a single joint affected. LEVEL OF EVIDENCE Level III.