The unstable hip in children with cerebral palsy: does an acetabuloplasty add midterm stability?

Purpose This study addresses whether an additional pelvic procedure is superior to a varus derotation osteotomy femur (VDRO) alone in unstable hips in children with cerebral palsy (CP). Methods All patients had unstable hips utilising the Melbourne Cerebral Palsy Hip Classification System (MCPHCS). We compared one group that underwent VDRO alone with one that had a combination of VDRO and Dega osteotomy (VDRO+). Measurements were taken before surgery, postoperatively, two years after surgery and at latest follow-up. Generalised estimating equations were used to account for known and unknown correlations between hips from bilateral cases. Results In total, 74 hips in 57 children fulfilled the inclusion criteria. There was no outcome difference between Gross Motor Function Classification System levels III, IV and V. Age at time of operation ranged from three to 16 years (mean 9.8 years). Mean follow-up was 49.1 months. In the VDRO group (28 hips) migration percentage (MP) changed from 61% preoperative to a final value of 35.7%. In the VDRO+ group (46 hips) the MP changed from 64.4% to 19.3%. At final follow-up 15 hips (54%) were stable in the VDRO group, 37 hips (83%) in the VDRO+ group. The odds ratio (OR) of hip stability at final follow-up was 3.5-times higher in the VDRO+ group versus the VDRO group (OR = 3.9; 95% confidence interval = 1.5 to 9.7; p = 0.004). Conclusion Reconstruction of unstable hips via VDRO + Dega in children with CP provides a higher likelihood of long-term stability than an isolated VDRO. Level of Evidence Level III, retrospective comparative study

Development of hip displacement in cerebral palsy: a longitudinal register study of 1,045 children

Background and purpose — Hip surveillance in children with cerebral palsy (CP) includes repeated radiographic hip examinations and measurements of the hip migration percentage (MP) to identify hips in need of surgery early, to prevent dislocation with the fewest number of radiographic examinations possible. We analyzed the early development of the MP in hips operated on to prevent hip dislocation and hips stabilized without surgery Patients and methods — From the Swedish Surveillance Programme for CP, 5,899 radiographic measurements from 1,045 children with a Gross Motor Function Classification System level III–V born in 1996–2011 were analyzed. For children operated on to prevent hip dislocation, measurements up to the most recent preoperative radiograph were included. The hip with highest MP was analyzed for each child. A mixed-effects model was used to estimate the development of the MP at each age for each child and the population mean. Results — In the 702 children who did not undergo preventive surgery, the mean MP increased with decreasing velocity up to age 6 years. Here it reached 24% (95% confidence interval [CI] 24–25), with a velocity of 0.3%/year (CI 0.0–0.5), remaining approximately stable up to age 12 years. In the 343 children who underwent preventive surgery (219 adductor–psoas lengthening, 124 varus derotation osteotomy of proximal femur), the mean MP increased with an increasing velocity from a mean of 30% (CI 27–32) 3 years before the operation. Interpretation — An increasing rate of hip displacement in hips with an MP > 24% indicates the need for preventive surgery. Hips stabilized without preventive surgery had a decreasing displacement rate and were usually stabilized with an MP < 30% at age 6 years.

Reliability and sensitivity of radiographic measures of hip dysplasia in childhood Charcot-Marie-Tooth disease

Background: Hip dysplasia is a lack of femoral head coverage and disruption of hip and acetabular alignment and congruency, with severity ranging from mild subluxation in nascent at-risk hips to complete dislocation. Presentation of hip dysplasia in neuromuscular conditions can be sub-clinical or associated with a limp with or without hip pain, abductor and flexor weakness and reduced hip range of motion. Untreated hip dysplasia leads to early onset osteoarthritis requiring hip arthroplasty in early adulthood. Hip dysplasia occurs in 6–20% of children with Charcot-Marie-Tooth disease, however little is known about the reliability and sensitivity of detection on plain film pelvic radiographs. Methods: 14 common measures of hip dysplasia on anteroposterior pelvis radiographs were independently assessed by 2 orthopaedic specialists in 30 ambulant children with Charcot-Marie-Tooth disease. Hip health was also categorised based on clinical impression to assess the sensitivity of radiographic measures to identify hip dysplasia status. Results: 8 measures (acetabular index, head width, lateral centre-edge angle, lateral uncoverage, medial joint width, migration percentage, neck shaft angle, triradiate status) exhibited ‘excellent’ reliability between clinical evaluators. 5 of the 30 patients (17%) were identified as having nascent hip dysplasia. Reliable radiographic measures that significantly distinguished between nascent hip dysplasia and healthy hips were acetabular index, lateral centre edge angle, medial joint width and migration percentage. Conclusions: We have identified a subset of reliable and sensitive radiographic hip measures in children with Charcot-Marie-Tooth disease to prioritise during hip screening to mitigate the deleterious effects of hip dysplasia, pain and disability in adulthood.

Hip displacement in children with cerebral palsy

Aims The migration percentage (MP) is one criterion used for surgery in dislocated or displaced hips in children with cerebral palsy (CP). The MP at which a displaced hip can no longer return to normal is unclear. The aim of this paper was to identify the point of no return of the MP through a large population-based study. Methods All children registered on the Cerebral Palsy Integrated Pathway Scotland surveillance programme undergo regular pelvic radiographs. Any child who had a MP measuring over 35% since the programme’s inception in 2013, in at least one hip and at one timepoint, was identified. The national radiography database was then interrogated to identify all pelvic radiographs for each of these children from birth through to the date of analysis. A minimum of a further two available radiographs following the initial measurement of MP ≥ 35% was required for inclusion. Results A total of 239 children (346 hips) were identified as suitable for analysis at a mean of 6.5 years (2.0 to 14.8) follow-up. In all, 1,485 radiographs taken both prior to and after a hip had a MP ≥ 35% were examined and the MP measured to identify any progression of displacement. Interrogation of the data identified that hips with a MP up to 46% returned to a MP below 40% without intervention, and all hips with a MP equal to or greater than 46% displaced further and the MP did not return to the normal range. Statistical analysis showed the result to be 98% specific with this degree of certainty that hips reaching a MP ≥ 46% would not spontaneously regress. Conclusion These findings are clinically relevant in showing that it may be reasonable to continue to monitor hips with a MP not exceeding 46%. This threshold will also guide referral for further management of a displacing hip. Cite this article: Bone Joint J 2021;103-B(2):411–414.

Is the Gothic Arch a reliable radiographic landmark for migration percentage in children with cerebral palsy?

Introduction Reimers migration percentage (MP) is the gold standard for measuring hip displacement in children with cerebral palsy (CP). Hip surveillance registries proposed using the top of the Gothic arch (GA) as a modification in patients with acetabular dysplasia because the classical method (CM) described by Reimers may underestimate hip migration. The aim of this study is to assess the inter- and intra-observer reliability of the modified method (MM) versus the CM and identify their effect on the MP. Methods We performed a retrospective review of 50 children with CP, who had a hip radiograph at our institution between 1st April 2014 and 28th February 2018. All hip radiographs were carefully selected to show the presence of a GA. Four observers measured the MP using the CM and MM for each patient. Interclass coefficient was used to estimate inter- and intra-observer reliability. Results Inter-observer reliability was excellent for the CM with ICC 0.96 (95% CI 0.94 to 0.97) and good for the MM, ICC 0.78 (95% CI 0.51 to 0.89) p < 0.001. Intra-observer reliability was excellent for both methods raging from ICC 0.94 to 0.99 for the CM and ICC 0.89 to 0.95 for the MM. The mean MP was 19% for the CM and 28% for the MM (p < 0.001). Conclusion The CM is more reliable than the MM to measure hip migration in children with CP. If the CM is used and acetabular dysplasia with a GA are present on the hip radiograph, then a 9% hip migration underestimation should be considered on decisions for both referral and surgical management. Level of evidence II

Outcome of Femoral Varus Derotational Osteotomy for the Spastic Hip Displacement: Implication for the Indication of Concomitant Pelvic Osteotomy

No previous studies have suggested a reliable criterion for determining the addition of a concomitant pelvic osteotomy by using a large patient cohort with quadriplegic cerebral palsy and a homogenous treatment entity of femoral varus derotational osteotomies (VDRO). In this retrospective study, we examined our results of hip reconstructions conducted without a concomitant pericapsular acetabuloplasty in patients with varying degrees of hip displacement. We wished to investigate potential predictors for re-subluxation or re-dislocation after the index operation, and to suggest the indications for a simultaneous pelvic osteotomy. We reviewed the results of 144 VDROs, with or without open reduction, in 72 patients, at a mean follow-up of 7.0 (2.0 to 16.0) years. Various radiographic parameters were measured, and surgical outcomes were assessed based on the final migration percentage (MP) and the Melbourne Cerebral Palsy Hip Classification Scale (MCPHCS) grades. The effects of potential predictive factors on the surgical outcome was assessed by multivariate regression analysis. A receiver operating characteristic (ROC) curve analysis was also performed to determine whether a threshold of each risk factor existed above which the rate of unsatisfactory outcomes was significantly increased. In total, 113 hips (78.5%) showed satisfactory results, classified as MCPHCS grades I, II, and III. Thirty-one hips (21.5%) showed unsatisfactory results, including six hip dislocations. Age at surgery and preoperative acetabular index had no effects on the results. Lower pre- and postoperative MP were found to be the influential predictors of successful outcomes. The inflection point of the ROC curve for unsatisfactory outcomes corresponded to the preoperative MP of 61.8% and the postoperative MP of 5.1%, respectively; these thresholds of the pre- and postoperative MP may serve as a guideline in the indication for a concomitant pelvic osteotomy. Our results also indicate that the severely subluxated or dislocated hip, as well as the hip in which the femoral head is successfully reduced by VDRO but is still contained within the dysplastic acetabulum, may benefit from concomitant pelvic osteotomy.

Soft tissue surgery as an initial treatment for hip displacement in spastic cerebral palsy

Objective: To use the measurement of migration percentage (MP) to evaluate the long-term radiographic results of soft tissue surgery as the first treatment for hip displacement in spastic bilateral cerebral palsy. A secondary objective was to identify predictive factors of stability (i.e., less than 30% of MP in the long term), after surgical correction. Methods: In this longitudinal cohort study, we reviewed the electronic medical records and radiographs of all consecutive patients with cerebral palsy operated for the correction of hip displacement between 1984 and 2013 in a referral orthopedic public hospital in Brazil. Patients were included if they had received, as the first surgical procedure, soft-tissue release. All surgeries were bilateral and symmetrical. We used the available radiographs to evaluate the migration percentage (MP), acetabular index (AI), pelvic obliquity (PO) angle, head-shaft angle (HSA), congruence and femoral head sphericity, and function using the GMFCS (Gross Motor Function Classification System). Results: we included 93 patients, all operated before being 12 years old, with follow-up of 10 years in average, 73 (78%) of them with good results (MP < 30%). We found association between preoperative MP ≤ 40%, AI ≤ 25°, and postoperative symmetry with good results, with a cut-off value of 38% of MP and 27° of acetabular index being predictive. Discussion: The role of soft tissue releases remains controversial owing to small sample sizes, heterogeneity, variety range of ages, definitions used for outcome, and lack of statistical quality. Our results were better in combined tenotomies, in diparetic patients aged more than six years, and in patients with lower initial values of MP and AI. Radiographic variables had good correlation with each other and association with results, with cut-off values for MP and AI PRE.

Migration percentage and odds of recurrence/subsequent surgery after treatment for hip subluxation in pediatric cerebral palsy: a meta-analysis and systematic review

Purpose This meta-analysis aims to systematically assess and quantitatively pool the best clinical evidence for migration percentage (MP) and odds ratio (OR) for recurrence/reoperation following treatment for hip subluxation in children with cerebral palsy (CP), including Botulinum Toxin A (BNT-A), soft-tissue lengthening and osteotomies Methods Pubmed, EMBASE and Cochrane were systematically searched from between 1 January 1953 and 11 January 2017 inclusive for studies reporting resubluxation/reoperation rates, and/or MP following treatment for hip subluxation in children with CP. The primary outcome was odds of resubluxation/reoperation. The secondary outcome was change in MP. Studies were graded for quality using the Newcastle Ottawa Scale. This meta-analysis was performed and reported in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Results A total of 14 studies were included in analysis of odds of resubluxation/reoperation and 24 studies were included in analysis of MP. The OR for resubluxation/reoperation was lower for combined osteotomies compared with femoral (OR = 0.49; 95% confidence interval (CI) 0.25 to 0.98) and for femoral osteotomy compared to soft-tissue procedures (OR = 0.20; 95% CI 0.07 to 0.61). There was no difference in odds of recurrence/reoperation between pelvic and femoral osteotomies (OR = 2.27; 95% CI 0.37 to 13.88). Combined osteotomies provided the greatest improvement in MP, while BoNT-A showed no improvement in MP. Conclusion Resubluxation/reoperation rates are high; management with osteotomies is preferred to soft-tissue procedures alone in preventing resubluxation/reoperation. This meta-analysis is limited by the observational nature and small sample sizes of many of the included studies, with their inherent risk of bias and lack of homogeneity of patient characteristics at baseline. It is possible that with larger and higher quality studies, the results and conclusions of this analysis may be altered.