Comparison of Autograft and Allograft Fixation in Pemberton Osteotomy

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By James J. McCarthy, MD; Douglas A. Palma, MD; Randal R. Betz, MD
ORTHOPEDICS 2008; 31:126
February 2008

Abstract

This retrospective study compared the results of autograft and allograft fixation in 29 children (36 hips) who underwent Pemberton osteotomy. Autograft fixation was used in 21 hips and allograft fixation was used in 15 hips. In the autograft group, 76% of patients had a successful result; 4 of 8 of patients with a neuromuscular disorder in this group had a successful result. In the allograft group, 93% of patients had a successful result; 6 of 7 of patients with a neuromuscular disorder in this group had a successful result. Pemberton osteotomy performed with allograft fixation provided similar or better results than autograft, especially in children with neuromuscular disorders. Level of Evidence: diagnostic study, Level III-2 (retrospective cohort study).

The Pemberton osteotomy was first described in 1965 as a treatment for acetabular dysplasia, either alone or associated with hip subluxation or dislocation.1 In this technique, Pemberton used autogenous iliac crest graft to wedge the osteotomy open and a spica cast to provide stability. The results were graded clinically, with >90% having good results. Since then, others2-4 have reported similar results. The Pemberton osteotomy also has been used successfully in children with static encephalopathy.5-7

Kessler et al8 reported their results using patellar allograft bone wedges with supplemental fixation with screws or allograft pins. They described results similar to the autograft results of the previous studies. In another study, Donati et al9 used xenograft (calf rib graft) in 93 operations. Researchers in both studies believed the initial stability of the graft was beneficial, especially for more immediate rehabilitation and return to function, and obviated the need for spica casting.

This study compared the use of autograft and allograft fixation in children undergoing Pemberton osteotomy, specifically focusing on the results of children with neuromuscular disorders...

Discussion

Our findings demonstrate the Pemberton osteotomy performed with allograft supplemental support provides results comparable to those of autograft and appears to be better than autograft in children with neuromuscular disorders such as spinal cord injury or myelomeningocele. Two other studies have examined the use of nonautograft material in Pemberton osteotomies.8,9 Satisfactory results with allograft were reported in both studies, and in both studies, the authors believed the immediate stability of the press-fit fixation allowed for earlier rehabilitation. Our results support these findings. However, our study is the first to directly compare the 2 procedures.

Our results are similar to those reported previously, 2,5,8 with an improvement in the acetabular index of approximately 20° (Table 5). When we applied our criteria for a satisfactory result to data in the literature,2,3,5,7,8 satisfactory results varied between 73% and 95%.

In our study, almost all of the children who had been diagnosed with developmental dysplasia of the hip had satisfactory results regardless of graft type. Only patients with neuromuscular disorders, particularly those with spinal cord injury or myelodysplasia, had unsatisfactory results, and they were much more likely to have a poor outcome if autograft was used. We believe this may be related to the poor bone quality in children with neuromuscular disorders and eventual collapse of the graft. This was particularly noted in the relative increase in acetabular index from postoperatively to most recent follow-up. In patients with neuromuscular disorders who had autograft, acetabular index increased from 11° postoperatively to 21° at most recent follow-up, whereas in the allograft group, acetabular index increased only slightly, from 6° to 8°. At final follow-up, the difference between the autograft and allograft groups was statistically significant.

Similar trends were noted for center edge angle and migration index, both of which deteriorated less in the allograft group. However, the differences between the two groups were not statistically significant.

Proximal femoral osteotomies were performed in both groups with roughly equal proportion. Five of 21 patients (24%) in the autograft group and 4 of 15 patients (27%) in the allograft group underwent femoral osteotomies. We expected the varus positioning of the proximal femur, which was a primary additional procedure, to affect the femoral head migration index and possibly the center edge angle but have less effect on the acetabular index, unless significant acetabular remodeling occurred. Therefore, we believe the acetabular index is the most important radiographic measurement for Pemberton osteotomies.

It is important to note that only a few of our patients were treated in spica casts regardless of graft type. In most cases, we used a hip orthosis that addressed abduction and allowed limited hip flexion.

Conclusion

Pemberton osteotomy performed with allograft fixation provides results comparable to autograft in children with developmental dysplasia of the hip and better than autograft in children with neuromuscular disorders.

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