Acetabular increase with modified Stahelli technique

Abstracts

Os autores apresentam neste trabalho um estudo retrospectivo realizado em 18 pacientes submetidos a tratamento cirúrgico de insuficiência acetabular pela osteotomia da pelve seguindo a técnica descrita por Lynn T. Staheli. Enfatizam a modificação da técnica deste autor, com a introdução do enxerto ósseo, retirado da tábua externa do ilíaco, numa fenda aprofundada até cerca da cortical interna do ilíaco. Os pacientes foram acompanhados através de consultas ambulatoriais previamente a cirurgia e pós-operatoriamente com seguimento que variou de 2 meses a 4 anos no serviço de ortopedia infantil do Hospital Independência - Complexo Hospitalar ULBRA/Porto Alegre-RS. O objetivo do trabalho foi avaliar o quadril acometido pré e pós-operatoriamente, demonstrando a evolução e vantagens da variação da técnica de Staheli desenvolvida neste serviço. Observou-se que a cirurgia, se realizada sob técnica adequada e em mãos experientes, torna-se uma fonte válida de tratamento para aquelas patologias que levam a uma insuficiente cobertura da cabeça femoral.

Aumento acetabular; osteotomia da pelve

ARTIGO DE REVISÃO

Acetabular increase with modified Stahelli technique

Sílvio Pereira Coelho^I; João Francisco Comnimos Corrêa^II; Leonardo do Nascimento^II

^IMédico ortopedista e traumatologista, membro titular da SBOT, chefe do serviço de Ortopedia Pediátrica do Hospital Independência - ULBRA/RS

^IIMédico residente do 3º ano em ortopedia e traumatologia do Hospital Independência - ULBRA/RS

^{Endereços para correspondência}

SUMMARY

The authors present in this paper a retrospective study of eighteen patients treated surgically for insufficiency of the acetabular coverage with the shelf procedure according to Lynn T. Staheli. This study was done at the Service of Pediatric Orthopedics of Hospital Independência - Complexo Hospitalar ULBRA/Porto Alegre-RS. They call attention to the modification of the surgical technique in that the bone graft taken from outer cortex of the iliac bone, is deepened in the slot in the superior rim of the acetabulum. The follow-up ranged from two months to four years. The aim of this paper was to evaluate the affected hip pre and postoperatively showing the results and the advantages of the modified shelf technique. They observed that if the surgery is performed according to the correct technique and by an experienced surgeon, it is a very good alternative to the treatment of those orthopedics diseases that lead to an insufficient coverage of the femur head.

Key words: acetabular augmentation, shelf, pelvic osteotomy.

INTRODUCTION

The treatment of the insufficiency of the acetabular coverage of the femoral head, caused by acetabular alterations or subluxation of the proximal femoral epiphysis, is a considerable challenge to the orthopedic surgeon. In the literature there are countless techniques and variations to solve this problem. The procedure that uses bone graft as a "shelf" in the superior rim of the acetabulum was commonly used during the first half of this century aiming an increase the acetabular surface in those cases of dysplasia of the acetabular development. However, during the last decades major emphasis was given to the pelvic redirectional osteothomy and to the displacement osteothomy⁶.

The surgical technique proposed by Lynn T. Stahelli was described as a kind of procedure of slotted acetabular augmentation⁵. This is a technique with simple methodology that increases the extension of the articular surface through an increase of the acetabular surface that can be easily controlled by the surgeon. Several pathologies modify the articular surface in the hip joint, mainly during the childhood. The definitive indication for the above technique would be nonspheric hip articulation or extreme deficiency^{3, 4, 5, 7}. Another indication is when the surgeon take into account the simplicity and easiness of this technique compared to the other ones available. Contraindications include dysplastic hips with spheric surface where the redirectional osteothomy is indicated^{1, 3}. In the Brazilian literature, up to this moment we could not find any publication related to this subject. Based in the experience gained with this technique, we developed in our Service modifications to the procedure described by Stahelli. Thus, in our indications the pathology of Legg-Calvé-Perthes had a special place. We believe that the increase of the acetabulum is a safe procedure, easy to be performed and with good functional results in those cases of patients with Perthes disease who need coverage for a subluxed femoral head. The objectives of our work are to present the modification of the technique developed by our team, the consequent benefits in the postoperatory phase and the results obtained.

MATERIAL AND METHODS

Retrospectively, 18 patients underwent a acetabular ostethomy according to the modified Stahelli technique fromSeptember/95 to June/99. The clinical characteristics of these patients were defined by: race, gender, side of the dysfunction, pathology related to the principal complaint and previous procedures.

Seven (38,8%) of the 18 patients evaluated were males and 11 (61,2%) were females. The age ranged from 8 to 13 years old with average of 10,6 years old. Fourteen (77,7%) were white and only 4 (22,3%) black. With respect to the initial diagnosis, 9 (50%) had Legg-Calvé-Perthes disease, 8 (44,4%) had congenital acetabular dysplasia and 1 (5,5%) had multiple epiphisial dysplasia (Graphic 1). The pathologies were in the right side in 10 (55,5%) patients and left side in 8 (44,5%) patients (Table 1)

The patients were evaluated trough a panoramic antero-posterior and Lounstein radiographic examination of the hip before and after surgery, with the use of Wiberg angle (CE angle - normal value 35 degrees) as determinant of the degree of acetabular coverage.

Evaluated before surgery patients presented with main complaint pain in the affected hip side in 16 (88,8%), claudication in 17 (94,4%), limited internal and external rotation in all patients evaluated, limited abduction and aduction in 16 patients (88,8%), limited flexion 13 patients (72,2%) (Graphic 2).

Technique: The patient must be in dorsal supine position with a support elevating the affected side in 15 degrees. An incision "bikini" type 1 cm below and paralel to the iliac crest, exposing the hip joint through na approach ileofemoral. The tendon of the reflex portion of the femoral rectus is identified, dissected in its extension and repaired after the section. The capsule is identified but not opened. The slot performed to acetabular increase is done in its margin with osteosthomy with depth greater than the one described by Staelli, aiming greater stability of the graft. After that the lateral portion of the iliac wing is decorticated to get a retangular bone graft, big enough for the coverage of the femoral head. Then, the graft is placed under impact deeply in the slot of the acetabular margin. Additional spongiosus bone graft is collected from the iliac, forming small pieces that will be placed over the cortico espongiosus shelf. This layer of graft is mantained by the reflex portion of the reconstructed femoral rectus (Fig. 1). Control X-rays are performed and the closing is performed with suture of the layers. In the majority of our patients cast is not used in the postoperatory days, since stability is achieved with the placement of the graft. The patient remains without support for 8 weeks, starting partial support during additional 2 to 4 weeks and full support thereafter.

RESULTS

The follow up time ranged from 2 months to 4 years, having all patients good adherence of the graft. The clinical assessment performed after 8 weeks, before was permitted to the patient partial support, showed decrease of 5 degrees in the internal rotation in 7 (38,8%) patients and 10 degrees in the external rotation in 10 (55,5%) patients; mild limitation of the abduction in all patients with range of 10 to 18 degrees compared to the contralateral side; flexion was mantained in all patients; sign of Thomas positive in 7 (38,8%) patients and shortening of isquitibials in just 1 (5,5%) patient. The improvement of the movement amplitude occurred in all patients that had follow up for more than 6 months (Fig. 2,3).

Wiberg angle, in average 22 degrees before surgery, had a significant increase, increasing to circa 38 degrees, with hipercorrection (angle greater than 35 degrees, but smaller than 42 degrees) in 11 (61,1%) patients (Graphic 3). Of the assessed patients 5 placed a pelvipodalic cast after surgery, what did not show significant difference in the postoperative examination when related to the other patients. We had a subject with cast that had precocious deambulation (3 weeks), what did not bring changes to the radiological picture (Fig. 4,5). There were no other complications related to the procedure.

All patients had good scarring, and the personal satisfaction (patient and family) with the results was good in 14 patients (77,7%), and regular satisfaction in 4 (22,2%). No patient considered the results as bad.

DISCUSSION

Among the several techniques used to correct insufficient acetabular coverage is the technique of Stahelli. This procedure is more frequently used in those patients with dysplasia of the acetabular development. However, in our experience, the advantages of this method were demonstrated in the the insufficient coverage of femoral head or subluxation of the femoral epiphisis in patients 8 or more years old with Perthes disease. These patients had benefit due to lower morbidity and less complications when compared to other techniques used to correct same abnormality. We did not observe significant alterations in the results when gender, race and involved side were considered.

Previous osteothomy with technique of Salter present in some patients was not an obstacle to the success of the procedure, however, attention must be given to the possible anatomic modifications secundary to the previous procedure. The hipercorrection of the graft has demonstrated that a greater correction index can be accepted and that the parameters set before can have bigger margins of acetabular coverage without significant clinical modifications. Due to the good integration of the bone graft placed more deeply in the acetabular rim, cast became necessary only for those children with behavior of difficult control by parents, among then one patient with hearing problems.

CONCLUSIONS

The results obtained allow us to conclude that:

1) The technique used is na effective method in the correction of the insufficient acetabular coverage when performed following the indications previously mentioned.

2) The use of this modified technique when compared to the results of the classic Stahelli technique did show lower morbidity with positive and reliable results.

3) Patients with age above 8 years old and with Perthes disease and subluxation of femoral head were well improved with this procedure, what shows this is a effective method to treat such problem.

4) The simplicity of the technique encourages us to use it in patients with insufficient acetabular coverage because a low number of complications is seen also by other authors in the existing literature.

REFERÊNCIAS

• 1. Beaty, J. H.: Congenital and Developmental Anomalies of Hip and Pelvis. Campbell Ortopedic Surgery 3:1049-1051, 1998.
• 2. Lyne, E.D.;Katcherian D.A.: Slotted acetabular augmentation in patients with neuromuscular disorders. J Pediatric Orth opedic 8: 278-84, 1988.
• 3. Pemberton, P. A.: Pericapsular osteotomy for congenital dislocation of the hip: Indications na techniques. Some long-term results. Journal of Bone Joint Surgery (Am) 47:437-449, 1965.
• 4. Smith, A. R.: The selving operation as an adjunct to open reduction in congenital dislocated hip and its use in paralytic and pathologic dislocation. Ann Surg 106:278-292, 1937.
• 5. Stahelli, L. T.: Slotted Acetabular Augmentation. Journal ofPediatric Orthopedics 1:321-327, 1981.
• 6. Stahelli, L.T.: Ampliação acetabular na displasia do quadril no adolesente. Tachdjan-Ortopedia Pediátrica 2:523-525, 1995.
• 7. Stahelli, L.T.; Chew D. E.: Slotted acetabular aumentation in childhood and adolescense. J Pediatric Orthopedic 12:569-80, 1992.

Endereços para correspondência

Rua João Manoel Guedes Falcão, 821

CEP. 5040-000 - Caxias do Sul - RS

ou Av. Bagé, 1259 Ap. 401

CEP 90460-080 - Porto Alegre -RS

Publication Dates

• Publication in this collection
  07 May 2007
• Date of issue
  Sept 2000