The effects of weight-bearing conditions on patellofemoral indices in individuals without and with patellofemoral pain syndrome.
OBJECTIVE
The purpose of this study is to evaluate differences between the patellofemoral joint indices after supine, non-weight-bearing and standing position, and weight-bearing Merchant view radiographs in individuals without and with patellofemoral pain syndrome (PFPS).


METHODS
Radiographs of 44 knees without PFPS and 51 knees with PFPS were retrospectively evaluated. In both positions, the non-weight-bearing and weight-bearing Merchant views, patellar indices such as patellar tilt angle, lateral patellofemoral angle, lateral subluxation distance, lateral patellar displacement, and congruence angle were measured, respectively. The differences between the patellofemoral joint indices in knees with and without PFPS were analyzed using univariate and multivariate regression analysis, in regards to correlation factors.


RESULTS
The patellar tilt angle (p = 0.0002), lateral subluxation distance (p = 0.038), lateral patellar displacement (p = 0.0004), and congruence angle (p < 0.0001) on the weight-bearing Merchant view was significantly decreased in normal knees without PFPS. In pathologic knees with PFPS, the patellar tilt angle (p < 0.0001), lateral subluxation distance (p < 0.0001), lateral patella displacement (p < 0.0001), and congruence angle (p < 0.0001) on weight-bearing Merchant view was also significantly decreased. The difference between the patellofemoral indices was significantly more in knees specifically with PFPS (p < 0.05).


CONCLUSIONS
These results suggest that patellofemoral indices measured during non-weight-bearing supine position do not sufficiently represent the patellofemoral kinematics during normal weight-bearing activities. We conclude that this study establishes the clinical significance and relevance of assessing the patellofemoral kinematics by weight-bearing, standing Merchant view radiographs, when evaluating patients with patellofemoral problems.
Department of Orthopedic Surgery, Konkuk University School of Medicine, 4-12, Hwayang-dong, Gwangjin-gu, Seoul, 143-729, Korea, thkim96@hanmail.net.
Tae-Hoon
TH
Kim
Anshul
A
Sobti
Suk-Ha
SH
Lee
Jong-Soo
JS
Lee
Kwang-Jun
KJ
Oh
D000293:Adolescent; D000328:Adult; D005260:Female; D006801:Humans; D008297:Male; D057071:Patellofemoral Joint / Q000473:pathology* / Q000503:physiopathology*; D046788:Patellofemoral Pain Syndrome / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D011859:Radiography; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D016474:Weight-Bearing; D055815:Young Adult