Legg-Calvé-Perthes disease is a childhood hip disorder which is common enough to be a significant public health problem (affects 1 in 740 boys between ages 0-14), but uncommon enough to have a sufficient number of patients from a single institution to perform a definitive prospective study comparing the results of current treatments. The present study will establish a database of prospectively identified patients with Legg-Calvé-Perthes (LCP) Disease and collect information regarding their presentation, treatment, and outcomes in the course of receiving currently available treatments.

This study seeks to compare the outcomes of current treatments in the management of different age groups (ages 1-6, 6-8, 8-11, >11) of patients with Perthes disease at two- and five-year followup and at skeletal maturity. For each age group, two to three common treatment regimens currently used by practicing pediatric orthopaedic surgeons will be compared. The intervention a patient receives is determined through physician treatment expertise, and is not pre-determined by the study.

Approximately 50 pediatric orthopaedic surgeons from pediatric centers in the US and other countries have agreed to participate in this database as members of the International Perthes Study Group (IPSG). TSRH will be the lead center. Sites who agree to participate will seek IRB approval from their own institutions. Data will be collected prospectively and entered into REDCap (Research Electronic Data Capture), a browser-based research database.

1-6 Cohort: For the 1-6 age patient group, patients involved in any treatment will be asked to participate in the study.

6-8 Cohort: For the 6-8 age patient group, patients presenting in an early stage of the disease (stage I or IIa), the surgeons who treat their patients with one of the following three treatment regimens currently used in practice will be asked to participate in the study :

1. Non-operative management (i.e., no osteotomy but can include soft tissue release);
2. Operative containment treatment (femoral or pelvic osteotomy or Shelf acetabuloplasty).

8-11 Cohort: For the 8-11 patient age group, patients presenting in an early stage of the disease (stage I or IIa), the surgeons who treat their patients with one of the following treatment regiments currently used in practice will be asked to participate in the study:

1. Non-operative management (i.e., no osteotomy);
2. Operative containment treatment (femoral or pelvic osteotomy or Shelf acetabuloplasty) followed by 6 weeks of postoperative non-weight bearing; and,
3. Operative containment treatment (femoral or pelvic osteotomy or Shelf acetabuloplasty) followed by 6 months of postoperative non-weight bearing.

>11 Cohort Registry: For the >11 patient age group, we will collect prospective data from surgeons who are currently treating their patients with any treatment regimens.

Patients who present to an IPSG member or their group during the late stages of the disease (stage IIb or stage III) will also be arranged into four separate age cohorts, identical to the list above. We will collect prospective data for these cases, as well.

Regardless of the patient's stage at enrollment, the patient's age at diagnosis or assigned cohort, the following data will be collected: information regarding patient characteristics at presentation, physical exam findings, responses to Perthes patient and/or outcomes questionnaires, and results of radiographic and MR imaging.

Participants will be assigned a unique study number. A secure web application, REDCap, will be used to capture and store research information including radiographic and MR images, clinical information, and de-identified outcomes questionnaire responses. Data will be transmitted and stored on a secure and dedicated server for the purpose of this study.

Inclusion Criteria:

• Diagnosed with Legg-Calvé-Perthes disease
• Between age 1-18
• Patients with possible secondary femoral osteonecrosis if over the age of 11 due to trauma or corticosteroid therapy are also eligible.

Exclusion Criteria:

• Patients with previous surgical treatment on the affected hip

Participants with a recent diagnosis of Perthes disease that are being followed by a participating orthopedic surgeon. Participants are invited to participate during a visit to their treating hospital.

Patient enrolled in study will be deidentified (a specific ID will be assigned to participants) in each respective site, Each site will be in charge of entering their respective data in a main database. Data analysis of this collective data will be done mainly through the host site.