A New Classification System for the Adult Dysplastic Hip Requiring Total Hip Arthroplasty: A Reliability Study

Current classification systems used for developmental dysplasia of the hip (DDH) in adult patients about to undergo total hip arthroplasty use a combined assessment of the acetabulum and femur which ignores femoral geometry and problems related to reconstruction of leg length. Currently accepted systems are those of Crowe and Hartofilakidis; it is our opinion that they do not predict surgical difficulties encountered at total hip arthroplasty. We describe a new classification system for adult DDH that divides the acetabulum and femur into separate components. The acetabular classification comprises: AI: Dysplastic acetabulum; AII: The acetabulum associated with a low femoral dislocation; AIII: The post-surgical acetabulum, with (AIIIa) or without retained metalwork (AIIIb). The femoral classification consists of: FI: Dysplastic femur but contained within true or low acetabulum; FII: The high femur; FIII: Post-surgical femur, again with or without metalwork (FIIIa and FIIIb). 50 pre-operative radiographs of hips with DDH about to undergo total hip replacement were assessed by orthopaedic consultants, registrars and medical students. They were classified using the new system, Crowe and Hartofilakidis systems. Interobserver and intraobserever reliability was assessed using Fleiss' kappa coefficient with combined (acetabulum and femur) kappa scores for the new system of 0.69 for interobserver and 0.67 for intraobserver reliability. This equated to ‘substantial agreement’ according to Landis and Koch and the new system showed at least comparable levels of reliability to the Hartofilakidis and Crowe systems. We have demonstrated reproducibility of our new classification system for DDH in the adult population and believe it could provide useful information when planning arthroplasty and be used to predict technical difficulties and outcome.

[1]  A. Assessment.  The Neer Classification System for Proximal Humeral Fractures , 2006 .

[2]  A. Chougle,et al.  Long-term survival of the acetabular component after total hip arthroplasty with cement in patients with developmental dysplasia of the hip. , 2006, The Journal of bone and joint surgery. American volume.

[3]  W. Puhl,et al.  Reliability of the Crowe und Hartofilakidis classifications used in the assessment of the adult dysplastic hip , 2006, Skeletal Radiology.

[4]  Werner Vach,et al.  The dependence of Cohen's kappa on the prevalence does not matter. , 2005, Journal of clinical epidemiology.

[5]  J. McCarthy,et al.  Developmental dysplasia of the hip (DDH) , 2005 .

[6]  C. Howie.  Operative Steps: The Dysplastic Hip , 2005 .

[7]  A. Chougle,et al.  Severity of hip dysplasia and loosening of the socket in cemented total hip replacement. A long-term follow-up. , 2005, The Journal of bone and joint surgery. British volume.

[8]  N. Clarke.  ii) Congenital dislocation of the hip , 2004 .

[9]  T. Karachalios,et al.  Total hip arthroplasty for congenital hip disease. , 2004, The Journal of bone and joint surgery. American volume.

[10]  C. Gozzard,et al.  A comparison of the reliability and validity of bone stock loss classification systems used for revision hip surgery. , 2003, The Journal of arthroplasty.

[11]  A. Hutchinson,et al.  Research methods used in developing and applying quality indicators in primary care , 2002, BMJ : British Medical Journal.

[12]  N Sugano,et al.  The morphology of the femur in developmental dysplasia of the hip. , 1998, The Journal of bone and joint surgery. British volume.

[13]  H. Cameron,et al.  Influence of the Crowe rating on the outcome of total hip arthroplasty in congenital hip dysplasia. , 1996, The Journal of arthroplasty.

[14]  N. Zacharakis,et al.  Congenital Hip Disease in Adults. Classification of Acetabular Deficiencies and Operative Treatment with Acetabuloplasty Combined with Total Hip Arthroplasty* , 1996, The Journal of bone and joint surgery. American volume.

[15]  J. Zuckerman,et al.  The Neer classification system for proximal humeral fractures. An assessment of interobserver reliability and intraobserver reproducibility. , 1993, The Journal of bone and joint surgery. American volume.

[16]  G. Hartofilakidis,et al.  Low friction arthroplasty for old untreated congenital dislocation of the hip. , 1988, The Journal of bone and joint surgery. British volume.

[17]  C. Ranawat,et al.  Total hip replacement in congenital dislocation and dysplasia of the hip. , 1979, The Journal of bone and joint surgery. American volume.

[18]  J. R. Landis,et al.  The measurement of observer agreement for categorical data. , 1977, Biometrics.

[19]  E. E. Specht.  Congenital dislocation of the hip. , 1974, American family physician.

[20]  Jacob Cohen.  A Coefficient of Agreement for Nominal Scales , 1960 .

[21]  J. Stol.  [Congenital dysplasia of the hip]. , 1951, Acta chirurgiae orthopaedicae et traumatologiae Cechoslovaca.