Outcome of bilateral hip reconstruction in unilateral hip subluxation in cerebral palsy: Comparison to unilateral hip reconstruction

Abstract

Objective: To evaluate the post-operative outcomes of the hips in CP patients with unilateral hip subluxation treated with bilateral and unilateral hip reconstruction.

Methods: A retrospective review was performed of all diplegic and quadriplegic patients with unilateral hip displacement treated with either bilateral or unilateral hip reconstructive surgery. Radiographic parameters [migration percentage (MP), pelvic obliquity angle (POA) and migration percentage difference (MPD)] and changes in functional ability (sitting, standing and walking) were evaluated and compared between the 2 groups. Failure was defined as post-operative MP>40%, POA>5° and MPD>30%.

Results: Eighteen patients had unilateral hip reconstruction and 42 patients had bilateral hip reconstruction. Mean age of 87 months and 90 months and means follow-up of 38 months and 40 months respectively. Post-operative MP was significant in both groups. However, of 18 patients in unilateral hip reconstruction group, 33.3% of patients had contralateral hip subluxation and 22.2% of patients had hip failure on the operated hip; compared to only one of 42 patients had hip failure and no contralateral hip problem in the other group. For assessment of pelvic symmetry, MPD was significantly improved in both group but POA was only significant in bilateral group. Overall functional improvement was significant in patients with bilateral hip reconstruction compared to unilateral group.

Conclusion: Bilateral hip reconstruction in unilateral displacement had shown to have better outcome in correcting unstable hip and pelvic asymmetry, thus provide good sitting balance and improvement in overall functional outcome.

Keywords: Bilateral hip reconstruction; Cerebral palsy; Functional outcome; Pelvic obliquity; Prophylactic hip reconstruction; Unilateral/contralateral hip subluxation.

Fig. 1

The graphs illustrated the correlation between pre- and post-operative MPD and POA in determining hip and pelvic symmetry for unilateral and bilateral hip reconstruction groups. In bilateral hip surgery, there was a significant correlation between MPD and POA (p < 0.005). However, in unilateral hip reconstruction group, post-operation MPD and POA correlation was not significant (p = 0.488). It showed that even though unilateral hip reconstruction able to improve the MPD, this procedure was inadequate to correct the POA.

Fig. 2

Pre- and post-operative MP, MPD and POA between unilateral and bilateral hip reconstruction over time (at 1-year and at last follow-up) were depicted in the above graph. Bilateral hip reconstruction (dotted line) had shown satisfactory outcome in all radiological parameters (in graph 1 to 4) pre- and post-surgery. In unilateral group, the mean MP had improved postoperatively in the operated hip as shown in graph 1; however, there was worsening of mean MP in contralateral hip over time (solid line) as depicted in graph 2. In graph 3 and 4, mean MPD and POA pre-operative and at last follow-up for unilateral hip reconstruction were increased as compared to bilateral hip reconstruction group.

Fig. 3

A, anteroposterior radiograph showed right hip subluxation (MP>60%) and pelvic obliquity (POA 8.4°) with elevation of right hip in a 10-years old spastic diplegic boy. The contralateral MP of 10% and noted coxa valga in both hips. B, bilateral VDRO and Dega osteotomy of right pelvic was performed. Both hips were symmetry after the operation; coxa valga and pelvic obliquity were corrected. The radiograph was 2 years after the surgery. C, right hip subluxation (MP>70%) with elevation of right hip in 9 years old spastic diplegic girl. Left hip was well seated. D, she was treated with right hip VDRO and Dega osteotomy; and femoral head was reduced after surgery. However, the pelvic obliquity still persisted; and contralateral hip coxa valga was not corrected After 1-year post surgery, left hip was subluxated (MP>30%) and pelvic was elevated to the left.