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Treatment of shepherd ’ s crook deformity in patients with polyostotic fibrous dysplasia using a new type of custom made retrograde intramedullary nail: a technical note

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ABSTRACT

Aims: The severe form of coxa vara, the ‘shepherd’s crook deformity’, is always a consequence of a locally extensive form of polyostotic fibrous dysplasia (or McCune-Albright syndrome). Treatment of this deformity is a challenge. The soft bone does not tolerate any implant that depends on the stability of the cortical bone (like plates or external fixators). Intramedullary nails are the most appropriate implants for stabilisation, but if they are inserted from the greater trochanter, they cannot correct the varus deformity enough.

Patients and methods: We have developed a special intramedullary nail that can be inserted from the osteotomy site and can be driven retrograde into the femoral neck in an appropriate valgus position. We have operated 15 legs in 13 patients. The average age at surgery was 14 years and 5 months (6 to 28.9). In all, 11 femora had been operated before (unsuccessfully) with various implants.

Results: The average follow-up was 54.2 months (7 to 132). The average correction of the neck/(distal) shaft angle was 57.5° (10° to 80°) ( = 72.8%). While pre-operatively none of the patients was able to walk without aid, at follow-up only one patient was unable to walk, three used the aid of crutches because of tibial lesions and one patient had an increased external rotation of the leg. At follow-up, most patients were free of pain. One implant broke and had to be replaced.

Conclusion: This new operative method offers the possibility of efficient correction and stabilisation of this severe and difficult deformation.

No MeSH data available.


Basic problem of the trochanteric insertion of an intramedullary nail. Left) In the normal position, the iliac bone forces the nail into a medial direction. Middle) Even in maximal adduction of the leg, the direction of the nail is not enough laterally directed. Right) The theoretical optimal direction of the nail for obtaining a true valgus of the neck.
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Figure 1: Basic problem of the trochanteric insertion of an intramedullary nail. Left) In the normal position, the iliac bone forces the nail into a medial direction. Middle) Even in maximal adduction of the leg, the direction of the nail is not enough laterally directed. Right) The theoretical optimal direction of the nail for obtaining a true valgus of the neck.

Mentions: It is therefore generally accepted that the most appropriate implant that can be used in severe cases of femoral neck deformity in polyostotic fibrous dysplasia is an intra-medullary nail. These nails are inserted from the greater trochanter, which means it is technically impossible to correct a severe varus deformity because the pelvis impedes the appropriate insertion of the nail, forcing the entry point to be too far lateral and the correction to be inadequate (Fig. 1). The corrective potential is therefore limited,4,5 except in mainly diaphyseal deformities.4,10 When using a conventional intramedullary nail, the valgisaton has to be obtained with other means. This can be achieved in a two-stage procedure with a valgus osteotomy using a blade plate or a dynamic hip screw as the first stage, and after consolidation, stabilisation with an intramedullary nail with a blade in the femoral neck as the second stage.3 In other reports, the Fassier-Duval nail had been used and the valgus osteotomy had been stabilised with two angulated pins and cerclage wires.11 A few cases have been described with the use of an intramedullary Expert-Synthes humeral nail,12 and one case report describes a patient with a fracture below a long blade plate, where the correction was done with the retrograde insertion of a conventional intramedullary nail from the fracture site.13 A new device called ‘gap nail’ has been recently presented. It is an intramedullary nail that can be inserted in an anterograde way from the greater trochanter or in a retrograde way from the knee. It can be combined with a plate that improves local stability at the greater trochanter (as long as the bone is not too soft in this area, which is usually the case in shepherd’s deformity). This nail certainly has a potential for correction of coxa vara, but it is not meant to be inserted from the osteotomy and therefore does not allow the same amount of valgisation and probably does not solve the problem in shepherd’s deformity. To our knowledge, no publication exists describing the use of this nail in such a deformity.


Treatment of shepherd ’ s crook deformity in patients with polyostotic fibrous dysplasia using a new type of custom made retrograde intramedullary nail: a technical note
Basic problem of the trochanteric insertion of an intramedullary nail. Left) In the normal position, the iliac bone forces the nail into a medial direction. Middle) Even in maximal adduction of the leg, the direction of the nail is not enough laterally directed. Right) The theoretical optimal direction of the nail for obtaining a true valgus of the neck.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5382339&req=5

Figure 1: Basic problem of the trochanteric insertion of an intramedullary nail. Left) In the normal position, the iliac bone forces the nail into a medial direction. Middle) Even in maximal adduction of the leg, the direction of the nail is not enough laterally directed. Right) The theoretical optimal direction of the nail for obtaining a true valgus of the neck.
Mentions: It is therefore generally accepted that the most appropriate implant that can be used in severe cases of femoral neck deformity in polyostotic fibrous dysplasia is an intra-medullary nail. These nails are inserted from the greater trochanter, which means it is technically impossible to correct a severe varus deformity because the pelvis impedes the appropriate insertion of the nail, forcing the entry point to be too far lateral and the correction to be inadequate (Fig. 1). The corrective potential is therefore limited,4,5 except in mainly diaphyseal deformities.4,10 When using a conventional intramedullary nail, the valgisaton has to be obtained with other means. This can be achieved in a two-stage procedure with a valgus osteotomy using a blade plate or a dynamic hip screw as the first stage, and after consolidation, stabilisation with an intramedullary nail with a blade in the femoral neck as the second stage.3 In other reports, the Fassier-Duval nail had been used and the valgus osteotomy had been stabilised with two angulated pins and cerclage wires.11 A few cases have been described with the use of an intramedullary Expert-Synthes humeral nail,12 and one case report describes a patient with a fracture below a long blade plate, where the correction was done with the retrograde insertion of a conventional intramedullary nail from the fracture site.13 A new device called ‘gap nail’ has been recently presented. It is an intramedullary nail that can be inserted in an anterograde way from the greater trochanter or in a retrograde way from the knee. It can be combined with a plate that improves local stability at the greater trochanter (as long as the bone is not too soft in this area, which is usually the case in shepherd’s deformity). This nail certainly has a potential for correction of coxa vara, but it is not meant to be inserted from the osteotomy and therefore does not allow the same amount of valgisation and probably does not solve the problem in shepherd’s deformity. To our knowledge, no publication exists describing the use of this nail in such a deformity.

View Article: PubMed Central - PubMed

ABSTRACT

Aims: The severe form of coxa vara, the ‘shepherd’s crook deformity’, is always a consequence of a locally extensive form of polyostotic fibrous dysplasia (or McCune-Albright syndrome). Treatment of this deformity is a challenge. The soft bone does not tolerate any implant that depends on the stability of the cortical bone (like plates or external fixators). Intramedullary nails are the most appropriate implants for stabilisation, but if they are inserted from the greater trochanter, they cannot correct the varus deformity enough.

Patients and methods: We have developed a special intramedullary nail that can be inserted from the osteotomy site and can be driven retrograde into the femoral neck in an appropriate valgus position. We have operated 15 legs in 13 patients. The average age at surgery was 14 years and 5 months (6 to 28.9). In all, 11 femora had been operated before (unsuccessfully) with various implants.

Results: The average follow-up was 54.2 months (7 to 132). The average correction of the neck/(distal) shaft angle was 57.5° (10° to 80°) ( = 72.8%). While pre-operatively none of the patients was able to walk without aid, at follow-up only one patient was unable to walk, three used the aid of crutches because of tibial lesions and one patient had an increased external rotation of the leg. At follow-up, most patients were free of pain. One implant broke and had to be replaced.

Conclusion: This new operative method offers the possibility of efficient correction and stabilisation of this severe and difficult deformation.

No MeSH data available.