A Prospective Nationwide Study of Perthes' Disease in Norway: Functional and Radiographic Outcomes at a Mean Follow-up of Twenty Years
Conditions: Legg Calve Perthes Disease
Sponsor: Oslo University Hospital

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The prospective Nationwide Study of Perthes` Disease 
in Norway: Functional and Radiographic Outcomes at a 
Mean Follow-up of Twenty Years 
 
 
 
 
 
 
 
 
 
Date 01.11.2018 
 
 

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Perthes study group 
Head of study group 
Stefan Huhnstock 
Consultant, Department for orthopaedic surgery  
Oslo University Hospital 
0027 Oslo 
Tel. 23076017 
Email : uxhuhs@ous-hf.no 
 
Senior investigators 
Terje Terjesen 
Professor emeritus dr. med 
Department for orthopaedic surgery  
Oslo University Hospital 
0027 Oslo 
Email: terje.terjesen@rikshospitalet.no 
 
Ola Wiig 
PhD 
Department for orthopaedic surgery  
Oslo University Hospital 
0027 Oslo 
Email: olawii@ous-hf.no 
 
 
The society of children’s orthopaedics initiated a nationwide study on Legg- Calve 
Perthes disease (LCPD) in 1996. All hospitals with orthopaedic service were involved 
and all new diagnosed patients with LCPD were registered. Several studies (1-7) 
were published based on this nationwide study. Ola Wiig and Stefan Huhnstock are 
members of the International Perthes Study Group, Texas Scottish Rite Hospital. 
 
 

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Background 
LCPD is a juvenile hip disease which affects children between 2 and 12 years of age. 
It is most commonly seen boys at the age around 5-6 years. The aetiology is still 
unknown. The pathophysiological key event is a partial or complete disruption of the 
blood supply to the femoral epiphysis. The epiphyseal cartilage, the secondary 
ossification centre and the metaphysis undergo subsequent changes due to partial or 
complete osteonecrosis. In the active stages of the disease the femoral epiphysis 
may deform due to altered mechanical properties. At time of healing the femoral head 
shape may vary compared to a normal hip. Depended on the residual deformity the 
patients may have symptoms and complaints even after time of healing and the hip 
function may be impaired in young adulthood. Such a hip may also predispose for 
early hip osteoarthritis. 
Since symptoms and hip changes are not only restricted to the active phases of the 
disease, it is mandatory to follow up the patients over a longer period. This study 
elucidates the hip function, the residual deformity and the patients reported outcome 
20 years after the diagnosis with LCPD: 
Unsolved issues with LCPD 
LCPD has been described for more than 100 years ago(8-10). However, there is no 
clear consensus on the epidemiology, aetiology the prognostic factors and treatment. 
   The treatment has changed dramatically in Norway over the last decades. Until the 
late 70s, children had been treated with traction and weight relief over several 
months in the active stages. Later, containment treatment was introduced and 
several orthotic devices had been introduced in order to maintain hip containment. 
Surgical Containment gained increasing popularity from the late 80s until today.   
   There is no consensus which treatment gives the most favourable outcomes. 
Several studies have been published and the results concerning the surgical (7, 11-
13) or non-surgical treatment is very divergent (14-16). Most of the studies are 
retrospective and have a short follow up time. Those studies therefore fail to evaluate 
the hip shape at time of healing. The main endpoints of most of the studies are based 
on radiographs, leaving the functional aspect unrecognized. Thus, little is known 
about patient’s hip function, quality of life and treatment satisfaction.  
 
Purpose of the study 
The purpose of the study is to evaluate long term outcomes, risk factors and patient 
reported outcomes in young adults, 20 years after LCPD.  
Material and methods 
From January 1996 until December 2000 al new diagnosed children with LCPD were 
registered in a nationwide Perthes study. It is a prospective, multicentre study 
involving 28 hospitals throughout Norway. The diagnosis was established by the local 

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orthopedic surgeon based on radiographic findings and clinical diagnostic. All 
radiographs were reviewed by Svein Svenningsen, Ola Wiig or Terje Terjesen. A total 
of 425 children with LCPD were involved in the study.  
 
The study will follow up all 425 patients and it is structured in 3 phases.  
 
Phase 1: Follow-up of all patients in the South-Eastern Norway Regional Health 
Authority (HSØ) 
208 patients with LCPD have been registered in HSØ(163 males and 45 females). 
Average age at diagnosis was 5.8 years (1.3 – 15.2). 
  
Phase 2: Follow-up of all patients in the Western and Central Norway Regional 
Health Authorities (HVoM) 
187 patients with LCPD have been registered in these two regions (141 males and 
46 females). Age at diagnosis was 5.7 years (1.7 – 13.5). 93 were treated with 
physiotherapy, 82 were treated with surgery and 11 patients with orthosis.  
 
Phase 3: Follow-up of all patients in the North Norway Regional Health 
Authorities (HN) 
27 patients with LCPD have been registered in this region (18 boys and 9 girls). Age 
at diagnosis was 6.1 years (1.8 – 13.1). 11 patients were treated with physiotherapy 
and 16 with orthosis.  
 
Demographics and clinical information have been reported of all 425 patients at the 
initial visit. Radiographs at diagnosis, 1 year and 5 years follow-up were collected. 
The extent of the femoral head necrosis was evaluated with the Catterall and lateral 
pillar classification (17, 18). At 5 years follow-up the residual deformity was classified 
with the modified Stulberg’s classification  
The present study is planning to invite all 425 patients to a clinical and radiographic 
examination. The project starts in 2019 with a pilot study where 20 randomised 
patients will be examined.  
The main study will proceed with the phases as described above. The examination 
will comprise a clinical visit with functional testing of the hip and radiographs of both 
hips.  
Endpoints (primary /secondary) 
Clinical endpoints will be the hip function and quality of life reported by the patients, 
using the Hip disability and Osteoarthritis Outcome Score (HOOS) (20). There will 
also be included functional and activity related aspects of a greater population based 
study in Oslo (21). Furthermore, length leg discrepancies, muscle impairment and 
Hip impingement tests will be performed.  
HOOS: Validated PROM.40 questions to evaluate hip symptoms, hip function on 
different activity levels and quality of life.  
 

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«Oslo population study»: Scientific population study in Oslo to evaluate cardiac risks 
(21).  
 
If patients would like to participate in the study, but fail to meet up for the visit, a short 
telephone interview will be performed including a short HOOS_PS form.  
 
Radiological endpoints 
a.) Stulberg classification  
b.) Coverage of the femoral head (CE angle)  
c.) Osteoarthritis -  Jacobsen et al.(22)  
d.) Alterations of the proximal femur (ATD, CCD)   
e.) Total hip replacement.  
Significance  
The Norwegian Perthes study is unique in the world. It is the world largest 
prospective study on Perthes disease. Other long term studies on LCPD are 
retrospective and they do not investigate the hip function. A variety of different 
classifications have been used, which makes a direct comparison impossible.  
No study has been using PROMS in the patient assessment. The present study will 
be the largest prospective study on this field. It elucidates both radiographic and 
clinical aspects 20 years after the diagnosis. The results may therefore have a 
significant impact on a better understanding and the future treatment of LCPD.  
 
 

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Plan 
2018  
 
Identification of all pasients 
 
 
2018 - 2019  
Pilotstudy with 20 randomised pasients  
2019  
 
Dataanalysis og pilot study  
2019 - 2020 
Phase 1 
2020   
 
Data analysis Phase 1 
2020 – 2021 
Phase 2:  
2022 
Data analaysis  
2023 
Phase 3:  
2023 
Data analysis  
2023 – 2025 
Publication 
 
 
Relevant literature 
 
1. 
Wiig O, Terjesen T, Svenningsen S. Prognostic factors and outcome of treatment in 
Perthes' disease: a prospective study of 368 patients with five-year follow-up. J Bone Joint 
Surg (Br). 2008;90(10):1364-71. 
2. 
Wiig O, Terjesen T, Svenningsen S. Inter-observer reliability of the Stulberg 
classification in the assessment of Perthes disease. Journal of children's orthopaedics. 
2007;1(2):101-5. 
3. 
Wiig O, Terjesen T, Svenningsen S. Inter-observer reliability of radiographic 
classifications and measurements in the assessment of Perthes' disease. Acta orthopaedica 
Scandinavica. 2002;73(5):523-30. 
4. 
Huhnstock S, Svenningsen S, Pripp AH, Terjesen T, Wiig O. The acetabulum in 
Perthes' disease: a prospective study of 123 children. Journal of children's orthopaedics. 
2014;8(6):457-65. 
5. 
Huhnstock S, Svenningsen S, Pripp AH, Terjesen T, Wiig O. The acetabulum in 
Perthes' disease: inter-observer agreement and reliability of radiographic measurements. Acta 
orthopaedica. 2014;85(5):506-12. 
6. 
Terjesen T, Wiig O, Svenningsen S. The natural history of Perthes' disease. Acta 
orthopaedica. 2010;81(6):708-14. 
7. 
Terjesen T, Wiig O, Svenningsen S. Varus femoral osteotomy improves sphericity of 
the femoral head in older children with severe form of Legg-Calve-Perthes disease. Clin 
Orthop Relat Res. 2012;470(9):2394-401. 
8. 
Calvé J. Sur une forme particulière de pseudo-coxalgie greffe sur des déformations 
caractérestiques del´extrémite supérieure du femur. Rev Chir (Paris). 1910;42:54-84. 
9. 
Legg AT. An obscure affection of the hip joint. Boston Med Surg J. 1910;162:202. 
10. 
Perthes GC. Über arthritis deformans juvenilis. Deutsch Z Chir 1910;107:111-59. 
11. 
Wiig O, Terjesen T, Svenningsen S. Prognostic factors and outcome of treatment in 
Perthes' disease: a prospective study of 368 patients with five-year follow-up. The Journal of 
bone and joint surgery British volume. 2008;90(10):1364-71. 

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12. 
Herring JA, Kim HT, Browne R. Legg-Calve-Perthes disease. Part II: Prospective 
multicenter study of the effect of treatment on outcome. The Journal of bone and joint surgery 
American volume. 2004;86-A(10):2121-34. 
13. 
Catterall A. The place of femoral osteotomy in the management of Legg-Calve-
Perthes disease. The Hip. 1985:24-7. 
14. 
Citlak A, Kerimoglu S, Baki C, Aydin H. Comparison between conservative and 
surgical treatment in Perthes disease. Archives of orthopaedic and trauma surgery. 
2012;132(1):87-92. 
15. 
Radlo W, Sulko J, Kotulski D. Outcome after conservative treatment of Perthes' 
disease in children. Ortopedia, traumatologia, rehabilitacja. 2004;6(5):589-94. 
16. 
Rich MM, Schoenecker PL. Management of Legg-Calve-Perthes disease using an A-
frame orthosis and hip range of motion: a 25-year experience. J Pediatr Orthop. 
2013;33(2):112-9. 
17. 
Catterall A. The natural history of Perthes' disease. The Journal of bone and joint 
surgery British volume. 1971;53(1):37-53. 
18. 
Herring JA, Neustadt JB, Williams JJ, Early JS, Browne RH. The lateral pillar 
classification of Legg-Calve-Perthes disease. Journal of pediatric orthopedics. 
1992;12(2):143-50. 
19. 
Harris WH. Traumatic arthritis of the hip after dislocation and acetabular fractures: 
treatment by mold arthroplasty. An end-result study using a new method of result evaluation. 
The Journal of bone and joint surgery American volume. 1969;51(4):737-55. 
20. 
Klassbo M, Larsson E, Mannevik E. Hip disability and osteoarthritis outcome score. 
An extension of the Western Ontario and McMaster Universities Osteoarthritis Index. 
Scandinavian journal of rheumatology. 2003;32(1):46-51. 
21. 
Holme I, Sogaard AJ, Lund-Larsen PG, Tonstad S, Haheim LL. Lonner det seg a leve 
sunt? Tidsskr Nor Laegeforen. 2006;126(17):2246-9. 
22. 
Jacobsen S, Sonne-Holm S. Hip dysplasia: a significant risk factor for the 
development of hip osteoarthritis. A cross-sectional survey. Rheumatology. 2005;44(2):211-8.