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O'Brien's Line Revisited: Does a Park-Harris Line of the Proximal Femur Predict Proximal Femoral Growth Disturbance
Keinan Agonias1, John Birch1,2, Daniel Sucato1,2
1Scottish Rite for Children.
Background:
O'Brien originally described a descending Park-Harris line of the proximal femur in patients treated for developmental dislocation of the hip (DDH), which reportedly predicted the absence of avascular necrosis/proximal femoral growth disturbance (PFGD). However, these findings have not been validated in a modern population using an objective classification system of PFGD. The purpose of this study is to evaluate the diagnostic utility of "O'Brien's Line" as a predictor of PFGD.
Methods:
We retrospectively reviewed patients treated with closed or open reduction for unilateral DDH. Each postoperative radiograph was evaluated for the presence and displacement of the Park-Harris line at the capital femoral epiphysis (medial) and the trochanteric apophysis (lateral), and the ratio of growth between them. PFGD was classified using Salter criteria at 12 to 24 months after the index reduction, and by Bucholz-Ogden classification at skeletal maturity.
Results:
One hundred seventeen patients (80.8% female and 61.5% closed reductions) were identified who underwent closed or open reduction at a mean age of 1.15±0.49 years. Park-Harris line was identified in 69.2% of hips at a mean of 4.0±1.59 months from reduction and disappeared a mean of 20.7±10.9 months after reduction. Park-Harris lines were less likely to appear in patients who were younger or with less severe dislocations by the International Hip Dysplasia Institute classification ( P <0.05 for each). There was no difference in the rate of PFGD in those patients with or without a Park-Harris line by Salter Criteria (19.8% vs. 16.7%, respectively, P =0.69) or Bucholz-Ogden Classification (23.5% vs. 22.2%, respectively, P =0.88). Even in patients 1 year of age or older (where the test had greater accuracy), a PPV of 81% to 84% and an NPV of 14% to 21% reveals that there was no difference in the risk of developing PFGD whether the line was present or absent (∼20% in both cases).
Conclusion:
The presence of the Park-Harris line following the reduction of DDH has limited diagnostic utility and does not accurately predict PFGD.
Level Of Evidence:
Level III-case-control study.
