The International Hip Dysplasia Institute (IHDI) classification is more informative than the Tönnis classification.

BACKGROUND: A new, supposedly more reproducible radiographic classification, set to replace the Tönnis classification of hip dislocations, was proposed in 2015: the International Hip Dysplasia Institute (IHDI) classification. PURPOSE: To compare the IHDI classification with the Tönnis classification when evaluating the severity of hip dislocations as well as their respective inter- and intra-observer reliability. MATERIAL AND METHODS: Since January 2000, Swedish-born children with a hip dislocation were prospectively registered. From this registry, radiographs of 97 hips in 79 patients (91% girls; median age = 7 months), born in 2000-2009, were analyzed. Two observers, one consultant and one resident, classified each hip both by IHDI and Tönnis twice. RESULTS: The IHDI classification had a more even distribution of grades with the majority in grade 2-3. The Tönnis classification graded the majority (77%) of the patients as grade 2 and equally among the other grades. There was moderate inter-observer agreement using both methods calculated with Kappa, 0.61 (95% confidence interval [CI] = 0.44-0.79) for Tönnis and 0.62 (95% CI = 0.49-0.74) for IHDI. The resident calculated Tönnis with weak intra-observer reliability of 0.57 (95% CI = 0.40-0.74) compared to high intra-observer reliability of 0.86 (95% CI = 0.74-0.98) for the consultant. Both observers graded IHDI with high intra-observer reliability. CONCLUSION: IHDI is more discriminative than the Tönnis classification when evaluating the severity of a hip dislocation in infants.

6 compared with 12 weeks treatment in the von Rosen splint is sufficient for Barlow and Ortolani positive hips: a comparative study of 237 neonates.

BACKGROUND AND PURPOSE: At our institution, newborns with Barlow or Ortolani positive hips have been treated for 12 weeks with the von Rosen abduction splint until 2012 when the treatment length was halved. We investigate whether acetabular development at 12 months of age and complications differ between hips treated with the von Rosen splint for 6 compared with 12 weeks. PATIENTS AND METHODS: 99 patients were included in the 6-week program and 138 patients in the 12-week program. We measured the acetabular index (AI) on standard anteroposterior pelvic radiographs taken at 12 months of age. Medical records were reviewed for complications and additional treatments until age 12 months. We used non-inferiority testing with an equivalence margin of 1° with a 95% confidence interval (CI) to compare the 2 groups. RESULTS: The mean AI at 12 months in the 6-week group was 25° (CI 24-26) compared with 25° (CI 25-26) in the 12-week group. Non-inferiority was demonstrated for the 6-week program: -0.2° (CI -1.1 to 0.7). In the 6-week group, 8 patients received additional treatment, including 1 hip dislocation that occurred between 6 weeks and 3 months. There were no additional treatments or complications in the 12-week group. CONCLUSION: AI was equal at 12 months of age for patients treated for 6 compared with 12 weeks in the von Rosen splint. The hip dislocation which occurred indicates that follow-up around 3 months of age is indicated.