Intraoperative assessment of closed reduction for developmental dislocation of the hip using 3-dimensional fluoroscopy

Intraoperative 3D Fluoroscopy During Open Reduction for DDH: An Effective Alternative to Postoperative CT/MRI

BACKGROUND

Computed tomography CT or magnetic resonance imaging (MRI) has been the most used imaging modality to assess hip reduction in developmental dysplasia of the hip (DDH) after open reduction (OR). In 2015, intraoperative 3D fluoroscopy (3D) was introduced at our center as an alternative to CT/MRI. 3D offers the advantage that if hip reduction is insufficient, it can be addressed at the time of surgery. The purpose of this study was to assess the efficacy of 3D in comparison to CT/MRI.

METHODS

This was a single-centre, retrospective comparative study of two consecutive cohorts: those with OR and 3D between 2015 and 2017 and those with OR and CT/MRI between 2012 and 2014. Time to imaging, re-imaging, length of stay (LOS), re-operation, and redislocation or subluxation after cast removal were evaluated.

RESULTS

Forty-two patients (46 hips) had 3D, and 30 patients (32 hips) had CT/MRI. Significant differences were found between groups in time to imaging, cast changes, and LOS. All 3D was intraoperative (46 hips), and only 69% (22 hips) of CT/MRI was on the day of surgery ( P <0.01). In the 3D group, 1 hip (2%) had a cast change under the same anesthetic, and 4 hips (13%) from CT/MRI had cast changes in subsequent surgery ( P =0.03). The mean LOS in days for 3D was 1.72 and 2.20 for CT/MRI ( P =0.03). There were no statistically significant differences between groups in further imaging and subluxations or re-dislocations at cast removal. Two hips (4%) in the 3D group had MRI, but with no further intervention ( P =0.51), and at cast removal, there were 3 subluxations in each group ( P =0.69) and 1 redislocation in the 3D group ( P =1.00).

CONCLUSIONS

Intraoperative 3D improved time to imaging, allowed for cast changes at surgery and had a shorter LOS. Moreover, there were no significant differences found in adverse outcomes between those who underwent 3D versus CT/MRI. 3D should thus be considered an effective alternative to CT/MRI for assessing hip reduction during OR for DDH.

LEVEL OF EVIDENCE

Diagnostic Study, level II.

Developmental Dysplasia of the Hip: Controversies in Management

PURPOSE OF REVIEW

Many aspects of developmental hip dysplasia (DDH) care and evaluation are still active areas of debate. Recent studies have provided more insight into these topics such as strategies for reducing osteonecrosis, assessing hip reduction after closed and open reduction, and the management of residual acetabular dysplasia.

RECENT FINDINGS

The presence of the ossific nucleus at the time of reduction does not alter the risk of osteonecrosis. The risk of osteonecrosis may be higher when hips are immobilized in excessive abduction. Limited sequence MRI may be the best choice for assessing hip reduction after closed and open reduction; however, new technologies are emerging such as 3D fluoroscopy and perfusion MRI. The treatment of residual acetabular dysplasia with bracing has been shown to be effective and the decision to perform a pelvic osteotomy is based on patient-specific factors. The spectrum of DDH treatment has evolved over the past several decades. Recent studies have provided insights into strategies for osteonecrosis prevention, hip evaluation during after reduction, and the management of residual acetabular dysplasia. However, there is ample room for additional and more rigorous studies guiding advanced imaging for assessing hip reduction such as 3D fluoroscopy and perfusion MRI, as well as the management of residual acetabular dysplasia.

The Added Value of Postoperative Axial Imaging in Developmental Dysplasia of the Hip

BACKGROUND

Redislocation is a dreaded complication after reduction of developmental dysplasia of the hip (DDH) in young children. While early detection facilitates urgent reoperation, delayed revisions are more complicated. Despite the weak evidence, an axial postoperative imaging tool is recommended. This study's goal is to compare the effectiveness of conventional pelvic radiography alone and axial imaging.

METHODS

Data were collected retrospectively between 2012 and 2016. One study group comprised consecutive patients who had operative reduction followed by routine low-dose computed tomography (CT). Hips that had anteroposterior pelvic radiographs as the only confirmatory tool were used as a reference group.

RESULTS

We identified 241 patients (339 hips). The mean age and follow up were 19.6 months ± 9.3, and 15.5 months ± 11.1, respectively. There were 147 hips in the radiography group and 192 in the CT group. Radiography detected only three out of nine redislocations during the same admission; in contrast, 2/2 redislocations in the routine CT group were addressed before hospital discharge (p<0.01). There was no significant delay in hospital discharge when CT was used (p= 0.28).

CONCLUSION

Conventional radiography is not as effective as axial imaging in preventing late detection of redislocation.

LEVEL OF EVIDENCE

level III, Diagnostic Study.

Use of inlet radiographs in the assessment of reduction after the surgical treatment of developmental dysplasia of the hip

AIMS

This pilot study aimed to evaluate prospectively the use of inlet radiographs of the hip as an alternative method of the assessment of reduction after the surgical treatment of developmental dysplasia of the hip (DDH).

PATIENTS AND METHODS

The children in this study underwent surgery between January 2013 and January 2015. All had inlet radiographs and CT scans post-operatively. Data were analysed by determining inter-observer reliability and intra-observer reproducibility, using the kappa value (K). Differences were settled by discussion between the two observers until a consensus was reached. The sensitivity and specificity of the radiographic and CT results were compared. A total of 26 radiographs were obtained from 23 children, with a mean age of 2.38 years (one to five).

RESULTS

Similar high levels of intra- and inter-observer agreement were observed (K = 0.834, 95% confidence interval (CI)). There was a high agreement between the radiographic and CT results (K = 0.834, 5% CI), with excellent sensitivity and a specificity of 95.5%.

CONCLUSION

These results suggest that inlet radiographs may be a reliable method of assessing the reduction of the hip after the surgical treatment of DDH. Cite this article: Bone Joint J 2017;99-B:697-701.

1.0 s Ultrafast MRI in non-sedated infants after reduction with spica casting for developmental dysplasia of the hip: a feasibility study

PURPOSE

The aim of this study was to first develop and use 1.0 s ultrafast magnetic resonance imaging (MRI) to confirm the location of the femoral head in non-sedated infants with developmental dysplasia of the hip (DDH) after reduction with spica cast application in clinical settings.

METHODS

The ultrafast acquisition was achieved by employing a balanced steady-state free precession sequence and immobilizing the patient with dedicated sandbags. On completion of the ultrafast MRI study, all infants were sedated for conventional MRI scanning. Two orthopaedic surgeons retrospectively evaluated the image quality, result of the reduction and total MRI study time (including patient immobilization, coil setup, and scanning) in 14 DDHs of 13 infants (one with bilateral DDHs).

RESULTS

Both reviewers stated that there were no motion artefacts for non-sedated infants during the ultrafast MRI and that the quality of both the ultrafast and conventional MRI images were acceptable to assess the femoral head location. Assessment of the reduction procedure resulted in two hips being categorized as 'incomplete reduction' requiring a re-reduction procedure. The total study time of ultrafast and conventional MRI was 6 ± 1 min and 14 ± 3 min, respectively (P < 0.001). No complications due to sedation, such as hypoxia, were reported. The average sedation waiting time was 1 h 25 min ± 34 min.

CONCLUSION

The ultrafast MRI procedure reported here can be readily employed to confirm the location of the femoral head in infants with DDHs, without the use of any sedation.