Abstract
DDH with or without previous treatment is the most frequent source of early hip OA in adolescents. Others are hip joint deformation following Legg-Calve-Perthes disease, slipped capital epiphysis or trauma. Secondary OA after rheumatoid arthritis, bacterial infection or as result of an hemophilic hip joint are relatively infrequent.
The choice of treatment depends on the type of the deformity and the severity of osteoarthritic changes. Osteotomies are favorably performed in adolescents. Arthrodesis is rarely accepted in this age group. In selected individuals THR is the matter of choice.
Pain, limping gait, restricted joint motion and sometimes clicking phemomena are the usual complains. Pain is usually aggravated by running and other sports activities.
Residual dysplasia of the hip with a spherical femoral head is best treated by a triple periacetabular osteotomy. The Bernese ostetomy of Ganz (3) and the triple osteotomy of Tönnis (9) are popular procedures. They mobilise an acetabular fragment, then reorient and stabilise the fragment in an optimal position. Internal fixation with screws provides stability and allows early mobilisation with partial weight bearing.
Chiari’s osteotomy is a supracetabular rotatory displacement osteotomy. Femoral head and joint capsule are medialised and covered by the osteomised iliac bone. The joint capsule in the weight bearing zone is transformed into fibrous cartilage by time. Congruent remodelling of the acetabular roof and fibrous tissue transformation into cartilage are biased by inproper height and orientation of the osteotomy (5). There is still an indication in severe DDH with subluxation of the femoral head and those with a severely deformed femoral head.
In pathomorphologies with aspherical femoral heads femoral osteotomies, usually valgus osteotomies, are required additionally in order to optimize the joint congruency
A dysplastic hip in a high dislocation and moderate to severe OA are contraindications.
Radiographic work up includes pelvic ap view and faux profil view. Assessment of the anterior and posterior acetabular rim indicate orientation of the acetabulum in terms of anteversion / retroversion. Orientation of the subchondral sclerosis over the femoral head is an indicator of femoral head coverage as CE-angle and AC-angle. 20°–30° abduction view in neutral rotation mimikes the postoperative acetabulum / femoral head relation. From CT-scans acetabular orientation ( ante-version / retroversion ), degenerative bone cysts, posteroinferior joint space and femoral head deformities and femoral neck osteophytes are depicted. Labrum pathology is dedectable by MRT and MRT-arthrography.
After treatment of DDH deformation of the femoral head and neck due to ischaemic necrosis develop in an incidence up to 20 %, depending on the method. Premature closure of the epiphyseal plate can also follow trauma, septic arthritis and Legg-Calve-Perthes disease. Most often an combination of acetabular dysplasia and coxa magna with short femoral neck and a high-standing greater trochanter are typical deformities. Specchiulli’s classification (8) is very helpful for deformations after avascular necrosis in DDH. Limping gait due to femoral shortening and insufficient strength of the abductor muscels are the major complains of adolescents. Symptoms exacerbate during walking of longer distances and restrict sports activities. Valgus osteotomy, Y-osteotomy, transfer of the greater trochanter alone or in combination with valgus osteotomy are appropiate methods to restore a better function and improve alignment of the mechanical axis to the knee joint. Femoral neck lengthening osteotomies (1,4) with distal-lateral transfer of the greater trochanter are advocated by several authors. Restoration of almost normal anatomy muscle function of the hip joint are realistic aims of these methods.
If the abductor muscel deficit is dominant and only a minor leg length discrepancy is in slight deformities, e.g. some Specchiulli’s type B2, we do not always need such complex procedures. Isolated transfer of the greater trochanter also improves the lever arm of the abductor muscles and therefore joint function, but does not influence leg length discrepancy. Disappearance of the Tren-delenburg-type gait is the most visible improvement of this procedure (7).
Total hip replacement (=THR) is rarely indicated in adolescents, but sometimes necessary for restoration of a almost normal quality of life. Especially in severe symptomatic OA after septic arthritis or trauma in some individuals remain only two options : arthrodesis or arthroplasty. Arthrodesis is a permanent solution for many years or even life time. Gait function is compromised remarkable (6) and specific compensatory mechanisms are adopted when walking. Excessive motion in the lumbar spine and ipsilateral knee provokes back and knee pain as well as osteoarthritic changes on the long run.
THR in young patients includes the risk of several revisions over life time , due to wear problems particularly in physically active individuals. A deficient acetabular bone stock as usual in severe acetabular dysplasia or poor bone quality after trauma or septic arthritis may compromize primary stability and secondary osteointegration. Nevertheless functional results and outcome (2) in terms of life quality are superior compared with various non-substituting procedures.
The abstracts were prepared by Mrs Anna Ligocka. Correspondence should be addressed to IX ICL of EFORT Organizing Committee, Department of Orthopaedics, ul. Kopernika 19, 31–501 Krakow, Poland
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