Operative treatment for type II avascular necrosis in developmental dysplasia of the hip

Guided growth versus varus osteotomy for type II avascular necrosis following surgery for developmental dysplasia of the hip

AIMS

The aim of this study was to compare outcomes of guided growth and varus osteotomy in treating Kalamchi type II avascular necrosis (AVN) after open reduction and Pemberton acetabuloplasty for developmental dysplasia of the hip (DDH).

METHODS

This retrospective study reviewed patients undergoing guided growth or varus osteotomy for Kalamchi type II AVN between September 2009 and January 2019. All children who had undergone open reduction and Pemberton acetabuloplasty for DDH with a minimum two-year follow-up were enrolled in the study. Demographic and radiological data, which included the head-shaft angle (HSA), neck-shaft angle (NSA), articulotrochanteric distance (ATD), Sharp angle (SA), and lateral centre-edge angle (LCEA) at baseline, two years, and at the extended follow-up, were compared. Revision rates were evaluated. Clinical outcomes using the Harris Hip Score were assessed two years postoperatively.

RESULTS

A total of 24 patients underwent guided growth and 19 underwent varus osteotomy, over a mean period of 3.3 years (95% confidence interval (CI) 2.8 to 3.8) and 5.2 years (95% CI 4.5 to 6.0), respectively. There were no differences in demographic and preoperative radiological data, except for a younger age at time of acetabuloplasty and larger ATD for the osteotomy group. The HSA did not differ at two years and the extended follow-up because of postoperative rebound in the osteotomy group. The NSA of the osteotomy group remained smaller postoperatively. There were no significant differences in the follow-up ATD, SA, and LCEA, except for a smaller two-year ATD of the osteotomy group. Seven patients (29.2%) in the guided growth group underwent revision surgery and none in the osteotomy group. The Harris Hip Score was similar between groups.

CONCLUSION

Guided growth and varus osteotomy had comparable results in improving caput valgum deformity, given the rebound of lateral tilting of the physis after osteotomy correction. There were no differences in clinical outcomes at two years postoperatively. Cite this article: Bone Joint J 2022;104-B(7):902-908.

The potential role of the Alsberg angle as a predictor of lateral growth disturbance of the capital femoral epiphysis in children with developmental dysplasia of the hip treated by closed reduction

PURPOSE

Early diagnosis and prevention of lateral growth disturbance of the capital femoral epiphysis is challenging after treatment for developmental dysplasia of the hip (DDH). The aim of the study was to evaluate the radiographic changes of the Alsberg angle (AA) in normal children and those with DDH, and to assess the role of AA as a potential predictor of lateral growth disturbance of the capital femoral epiphysis.

METHODS

AA was measured on the anterior-posterior pelvic radiographs of 1000 normal children ranging in age from one to ten years and in 66 children (92 hips) with DDH treated by closed reduction (CR). A comparative analysis was performed.

RESULTS

In the normal children, mean AA decreased linearly with age, from 76° at age one year to 65° at age ten years, irrespective of gender and laterality. In children with DDH, the average AA was 81.5°(sd 3.9°; 74° to 87°) prior to CR; it was 75.9° (sd 4.5°; 68° to 83°) in normal children of the same age (p < 0.001). Among the 42 children (64 hips) with successfully and uneventfully treated DDH, AA reached normal values between the ages of five and six years. In contrast, children with lateral growth disturbance of the proximal femur physis (24 children, 28 hips) showed significantly higher AA values in comparison with the age-matched controls.

CONCLUSION

In DDH patients with successful CR, AA could be expected to match normal values in children between the ages of five and six years. On the other hand, AA can be used as an early predictor for lateral growth disturbance of the capital femoral epiphysis.

LEVEL OF EVIDENCE

Level III.

Loading rates during walking in adolescents with type II osteonecrosis secondary to pelvic osteotomy

Although Pemberton osteotomy has shown a high success rate even in older children, the occurrence of osteonecrosis (ON) remains one of the most severe complications, leading to premature osteoarthritis. Patients with type II ON are characterized by a valgus deformity of the proximal femur with altered musculoskeletal conditions, affecting the ability to attenuate or sustain the impulsive loading from the ground reaction force. It remains unclear whether these conditions also predispose these patients to harmful impulsive loadings. This study aimed to bridge the gap by measuring the loading rates in the lower limbs during level walking in adolescents who were treated during their infancy for unilateral developmental dysplasia of the hip by a pelvic osteotomy, with or without having developed type II ON. Patients with type II ON were found to display increased loading rates, not only at both the affected and unaffected hip, but also at other joints of the affected limb during level walking when compared to patients without ON changes (p < 0.05). These results suggest that patients with type II ON may be at a higher risk of developing premature hip osteoarthritis that is closely related to abnormal loading rates during gait. It is suggested that regular monitoring of joint loading rates in patients with type II ON is necessary for early identification of damaging loadings, and that early intervention aimed at reducing these loadings should be considered. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:2199-2206, 2016.

Long-term outcome following medial open reduction in developmental dysplasia of the hip: a retrospective cohort study

INTRODUCTION

Avascular necrosis (AVN) is a serious complication of treatment for developmental dysplasia of the hip. There is ongoing controversy regarding AVN and its influence on hip development following medial open reduction (MOR).

PURPOSE

The aim of our study was to (1) determine the long-term prevalence of AVN following MOR, (2) evaluate hip development after MOR, and (3) identify predictors of AVN and radiographic outcome at skeletal maturity after MOR.

METHODS

A retrospective cohort analysis of 60 patients (70 hips) who underwent MOR with a mean follow-up of 10.83 years (5.23-16.74) was conducted. AVN was recorded according to Bucholz and Ogden classification and radiographic outcome based on Severin grading. AVN and hip morphology related to length of follow-up were evaluated. Chi-squared and t-tests were used to identify relationships between AVN and other variables. Logistic regression was used to assess predictors of AVN and Severin outcome.

RESULTS

The rate of clinically significant AVN (types 2-4) following MOR was 32.9 % with type 2 accounting for 82.6 % of these cases. While early acetabular development was satisfactory, long-term outcome was unsatisfactory in 26 % of cases with AVN (vs 8.7 % of cases without AVN). A higher rate of AVN was identified when hips were immobilized in ≥60° of abduction postoperatively. A higher rate of poor Severin outcome was identified in hips with AVN.

CONCLUSIONS

Our findings suggest that there is a high rate of AVN and unsatisfactory long-term outcome following MOR. AVN remains a significant concern following MOR surgery for developmental dysplasia of the hip that may not be apparent until long-term evaluation.

The influence of the choice of closing wedge angle on leg length discrepancy after proximal femoral varus osteotomy

Proximal femoral varus osteotomy improves the biomechanics of the hip and can stimulate normal acetabular development in a dysplastic hip. Medial closing wedge osteotomy remains the most popular technique, but is associated with shortening of the ipsilateral femur. We produced a trigonometric formula which may be used pre-operatively to predict the resultant leg length discrepancy (LLD). We retrospectively examined the influence of the choice of angle in a closing wedge femoral osteotomy on LLD in 120 patients (135 osteotomies, 53% male, mean age six years, (3 to 21), 96% caucasian) over a 15-year period (1998 to 2013). A total of 16 of these patients were excluded due to under or over varus correction. The patients were divided into three age groups: paediatric (< 10 years), adolescent (10 to 16 years) and adult (> 16 years). When using the same saw blades as in this series, the results indicated that for each 10° of angle of resection the resultant LLD equates approximately to multiples of 4 mm, 8 mm and 12 mm in the three age groups, respectively. Statistical testing of the 59 patients who had a complete set of pre- and post-operative standing long leg radiographs, revealed a Pearson's correlation coefficient for predicted versus radiologically observed shortening when using a wedge of either 10° or 20° of 0.93 (p < 0.001). The 95% limits of agreement from the Bland-Altman analysis for this subgroup were -3.5 mm to +3.3 mm. It has been accepted that a 10 mm discrepancy is clinically acceptable. This study identified a geometric model that provided satisfactory accuracy when using specific saw blades of known thicknesses for this formula to be used in clinical practice.

The incidence of avascular necrosis and the radiographic outcome following medial open reduction in children with developmental dysplasia of the hip: a systematic review

The incidence of clinically significant avascular necrosis (AVN) following medial open reduction of the dislocated hip in children with developmental dysplasia of the hip (DDH) remains unknown. We performed a systematic review of the literature to identify all clinical studies reporting the results of medial open reduction surgery. A total of 14 papers reporting 734 hips met the inclusion criteria. The mean follow-up was 10.9 years (2 to 28). The rate of clinically significant AVN (types 2 to 4) was 20% (149/734). From these papers 221 hips in 174 children had sufficient information to permit more detailed analysis. The rate of AVN increased with the length of follow-up to 24% at skeletal maturity, with type 2 AVN predominating in hips after five years' follow-up. The presence of AVN resulted in a higher incidence of an unsatisfactory outcome at skeletal maturity (55% vs 20% in hips with no AVN; p < 0.001). A higher rate of AVN was identified when surgery was performed in children aged < 12 months, and when hips were immobilised in ≥ 60° of abduction post-operatively. Multivariate analysis showed that younger age at operation, need for further surgery and post-operative hip abduction of ≥ 60° increased the risk of the development of clinically significant AVN.

Three-dimensional computerized tomographic analysis of the deformity of lateral growth disturbance of proximal femoral physis

BACKGROUND

Lateral growth disturbance of the proximal femoral physis after treatment of developmental dysplasia of the hip, also known as type 2 avascular necrosis, has been described in a 2-dimensional (2D) plane with standard radiographs. It is not well described in the 3-dimensional plane using 3D computed tomography (CT) scan. The purpose of this study was to define the anatomy of the proximal femur after the lateral growth disturbance of the proximal femoral physis with 3D CT scans.

METHODS

Ten patients (11 hips) with lateral growth disturbance of the proximal femoral physis after treatment for developmental dysplasia of the hip (9 hips) and extracorporeal membrane oxygenation (2 hips), were studied with 2D and 3D CT methods. CT was done at an average age of 12.5 years (range, 9.8 to 16.69).

RESULTS

In addition to the typical valgus configuration in the coronal plane, increased antetorsion of the femur (10 of 11 hips) and increased anteversion of the femoral head (8 of 11 hips) were a common finding seen in the transverse plane. In 6 of 7 hips for which the CT scan was performed before the closure of the capital femoral epiphysis, the physeal bridge was seen to be located in the anterolateral (5 hips) or posterolateral (1 hip) area of the proximal femoral physis. The version of the femoral head was correlated to the location of the physeal bridge. Acetabular dysplasia was seen in 4 hips. In the 3D reconstruction view, flexion deformity of the femoral head was seen in 6 hips and lack of coverage at the anterolateral portion of the femoral head was observed in 6 hips.

CONCLUSIONS

The treating surgeon should be aware of the often marked antetorsion and also anteversion of the femoral head and neck associated with lateral growth disturbance of the proximal femoral physis. This knowledge allows surgical planning to correct rotational and sagittal plane correction of the proximal femur, which will allow normalizing hip mechanics. Acetabular side correction also may be needed if acetabular dysplasia is present.

LEVEL OF EVIDENCE

Level III, diagnostic study.

A radiological classification of lateral growth arrest of the proximal femoral physis after treatment for developmental dysplasia of the hip

BACKGROUND

After treatment of developmental dysplasia of the hip, lateral growth arrest of the physis of the proximal femur resulting in disturbance of the growth of the capital femoral epiphysis is not uncommon. The changes are usually not apparent until approximately the age of 9 years. The residual deformity has a variable prognosis at skeletal maturity. The purpose of this study was to assess the long-term impact of these proximal femoral changes on the function of the hips.

METHODS

We reviewed the natural history of 22 hips in 21 patients who had a lateral growth arrest of the physis of the proximal femur after treatment of developmental dysplasia of the hip. The average age at follow-up was 22 years. The radiographic changes in the proximal femur after the growth arrest were analyzed. Radiographic outcome was assessed using Severin criteria, with classes I and II being graded as satisfactory and classes III and IV being graded as unsatisfactory. The Iowa hip score was used to assess clinical outcome.

RESULTS

The consistent radiographic findings were a shortened lateral neck length in comparison with the medial neck length and lateral tilting of the capital femoral epiphysis, both of which were evident by an average age of 9 years. Overall, 41% of hips had a satisfactory radiological outcome according to the Severin classification. Two types of changes were observed in the proximal femur: a varus configuration (pattern A, 12 hips) and a valgus configuration (pattern B, 10 hips). Pattern A hips (varus) had a satisfactory result in 75% of the hips compared with none in pattern B hips (valgus).

CONCLUSIONS

Valgus orientation of the proximal femur (pattern B) leads to disruption of the Shenton line, progressive subluxation, and acetabular dysplasia which resulted in class III or class IV Severin grade hips leading to a poorer clinical and radiological outcome at long-term follow-up.

LEVEL OF EVIDENCE

Level III-Diagnostic study.