Treatment of sickle cell disease's hip necrosis by core decompression: a prospective case-control study.

INTRODUCTION: The young age of patients, total arthroplasties complications risks, and implant costs justify evaluation of the results of core decompression in the treatment of sickle-cell disease avascular necrosis of the femoral head (ONFH).

HYPOTHESIS: In sickle-cell disease necrosis, core decompression offers good relief from pain and delays the use of total arthroplasty in comparison to a conservatively treated control group by a simple non-weight bearing protocol.

MATERIALS AND METHODS: From 1994 to 2008, among 215 drepanocytic adults, 42 patients (22 genotype SS, 20 genotype SC; 15 men, 27 women) presented symptomatic ONFH. We report the data from a prospective study of two patients' groups: a non-operated group (16 patients aged 36.5+/-6.5 years, 23 hips) and an operated group (26 patients aged 30.3+/-2.8 years, 42 hips). The results were considered on the basis of change in clinical status according to the numeric evaluation of pain scale, the functional score of Merle d'Aubigné-Postel (MAP), the radiological progression of lesions, and the time delay to total arthroplasty.

RESULTS: Twenty-three hips were conservatively treated by discharge (a pair of canes). After a follow-up period of 13.4+/-0.5 years, no pain improvement was noted (p=0.76), and MAP score was unchanged (p=0.27). Out of 23 hips managed by discharge, 9 stage IV hips (degenerative arthritis, 39.1%) underwent arthroplasty after an average delay of 2.6+/-2.4 years. Forty-two hips were treated by core decompression. The duration of follow-up was 11.3+/-1.8 years. Postoperatively, pain reduction and MAP score improvement were significant in 39 out of 42 hips (93%, p<0.0001). Twenty-nine out of these 42 hips had a favorable evolution. Ten hips (23.8%) progressed to total arthroplasty, after a period of 7.4+/-2.7 years, longer than the one of the non-operated group (p=0.0007). By comparing the two groups (operated and non-operated), the benefit of core decompression appeared very significant (p<0.0001). In addition to allocating patients osteonecrosis stages, the Koo and Kim Index estimated the severity and evolution of necrotic lesions in both groups. It indicated decline in the non-operated group (p=0.002) and improvement for operated patients (p=0.0002).

DISCUSSION: Core decompression had a favorable clinical and radiological outcome superior to surgical abstention. Stages I and II ONFH remained stable after drilling, necessitating no arthroplasty (considered as a failure of drilling). The Koo and Kim Index above 30 degrees in the non-operated group was a significant indicator of lesions degradation (p=0.002). In addition to the indolence obtained by core decompression, the benefit of drilling was manifested by the prolonging the adjournment before arthroplasty end-point. It was respectively 7.4+/-2.7 years in the operated group versus 2.6+/-2.4 years in the non-operated group (difference of 4.8 years, p<0.01).

CONCLUSION: The technique of core decompression remains a valid option place in the treatment sickle-cell disease avascular necrosis of the femoral head (ONFH). It may be especially recommended in under-equipped regions where drepanocytosis and its osteo-articular complications are frequent.

LEVEL OF EVIDENCE: Level III case-control therapeutic study.