Hip Magnetic Resonance Imaging by Young-Jo Kim & Tallal Charles Mamisch

Author:Young-Jo Kim & Tallal Charles Mamisch
Language: eng
Format: epub
Publisher: Springer New York, New York, NY

Natural History

The natural history of LCP disease is significantly affected by several factors. The age at onset is strongly associated with outcome. Onset before the age of 5 is associated with a generally favorable outcome. Similarly, young age at reossification offers a favorable prognosis as the potential for remodeling is greater. The extent of epiphyseal involvement is also predictive of outcome, with involvement of the entire head having the most unfavorable prognosis. Sparing of the lateral column of the epiphysis implies a good prognosis, as it may prevent additional collapse of the epiphysis and subsequent deformity. Additional, radiographic features that are associated with poor outcome include the Gage sign, calcification lateral to the epiphysis, metaphyseal radiolucencies, lateral subluxation, and a horizontal growth plate orientation [48].

At 20- to 40-year follow-up, most patients are pain-free despite radiographic evidence of deformity. Development of hip pain has been associated with irregularity and flattening of the femoral head, as well as deformities secondary to physeal closure (coxa breva, trochanteric overgrowth) that contribute to biomechanical overload. At longer term follow-up, the long-term outcomes of LCP appear to deteriorate. Mcandrew et al. [49] reported on the 48-year follow-up of a cohort and found that 50 % had disabling pain and 40 % had already undergone arthroplasty. Mose et al. [50] reported follow-up of a cohort of LCP greater than 60 years old and found that all hips with irregular femoral heads developed osteoarthritis, and nearly two-thirds of those with spherical femoral heads also had evidence of osteoarthritis. Lecuire [51] reported long-term follow-up of 51 hips at a mean follow-up of 50.2 years. Twenty-four percent had undergone total hip arthroplasty, with an additional 33 % reporting mild to severe pain. Three degree of deformity correlated with long-term outcome. Irregular and very irregular hips generally had significant pain and frequently required arthroplasty. Significant deterioration was noted between the 34- and 50-year outcomes of this cohort.

Stulberg et al. [44] reported long-term outcomes of cohorts of LCP patients from three centers. They found that the degree of femoral head deformity and the presence of acetabular incongruity strongly correlated with the risk and timing of development of osteoarthritis. Hips with “aspherical incongruency” (Class V) develop osteoarthritis at an early age. These hips are generally thought to be the result of LCP in older patients where compensatory acetabular remodeling fails to occur. Hips with “aspherical congruency” (Class III–IV) also generally develop osteoarthritis at a later age. Secondary acetabular remodeling occurs in these hips to allow congruency.

Ross et al. [52] demonstrated high rates of chondral and labral pathology in a cohort of patients with hip pain and residual Perthes deformities. Labral pathology was present in 76 %, acetabular chondral pathology in 59 %, and femoral head chondral pathology in 81 %. The presence of acetabular dysplasia correlated with less severe chondral changes, while trochanteric overgrowth was associated with more severe chondral changes.

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