Hip joint pain in children with cerebral palsy and developmental dysplasia of the hip: why are the differences so huge?

What Do We Really Know About the Natural History of Spastic Hip Dysplasia and Pain in Total-involvement Cerebral Palsy? A Systematic Review

BACKGROUND

Hip surveillance protocols and surgery for spastic hip dysplasia have become standard of care for children with cerebral palsy (CP) out of concern for long-term sequelae, including pain. It is unclear if available data support that spastic hip dysplasia/dislocation independently correlates with pain in total-involvement CP. A better understanding of this correlation may help guide decision-making for these medically complex patients.

METHODS

We undertook a systematic literature review to assess published data on the association of spastic hip dysplasia and pain in total-involvement CP using PubMed (which includes the MedLine databases) and EMBASE databases. A total of 114 English-language articles were identified. Fifteen articles met the inclusion criteria and were evaluated using the PRISMA guidelines for systematic reviews.

RESULTS

Of 15 articles that specifically assessed the association of spastic hip dysplasia and pain, 5 articles provided strong evidence per our criteria regarding the correlation of pain and spastic hip dysplasia. All 5 articles described the severity of CP in their studied population, radiographically defined hip displacement, included a control group, and described how pain was assessed. Nevertheless, there was no standard classification of dysplasia between studies and the ages of patients and methods of pain determination varied. Four of the articles provided level III evidence and one provided level II evidence. Of these 5 articles with the strongest available evidence, data from 2 did not support a correlation between hip dysplasia and hip pain, 2 supported a correlation, and 1 was equivocal.

CONCLUSIONS

Even the best available evidence on spastic hip dysplasia and pain reveals no consensus or conclusion on whether spastic hip dysplasia and dislocation in total-involvement CP is independently correlated with pain.

LEVEL OF EVIDENCE

Level III-Prognostic study.

Cerebral Palsy: Hip Surveillance

Patients with cerebral palsy are known to be at risk for hip displacement and dislocation. Progressive hip displacement is known to cause a variety of problems including pain, impaired sitting balance, difficulty with perineal care, and decreased quality of life. To avoid these problems, hip reconstruction may be recommended and has been shown to lead to significant improvements in pain and health-related quality of life. To properly identify patients in need of intervention for hip displacement, hip surveillance is an active program consisting of clinical and radiographic monitoring in patients with cerebral palsy that allows for early detection of hip displacement in those at risk. As such, all children with cerebral palsy should be referred for hip surveillance at age 2 years. A growing body of literature has shown that hip surveillance along with appropriate orthopedic management decreases or prevents the incidence of hip dislocations, with direct implications on overall quality of life, in children with cerebral palsy. [Pediatr Ann. 2022;51(9):e353-e356.].

Healthy Hip Joints Have Different Macroscopic and Microscopic Capsular Nerve Architecture Compared With Hips With Osteoarthritis, Femoroacetabular Impingement Syndrome, and Developmental Dysplasia of the Hip: A Systematic Review

Purpose

To perform a systematic review to identify macroscopic and microscopic patterns and differences in hip capsule innervation between normal hips and hips with osteoarthritis (OA), femoroacetabular impingement (FAI) syndrome, and developmental dysplasia of the hip (DDH).

Methods

A systematic review was performed using Preferred Reporting Items for Systematic reviews and Meta-Analyses guidelines. Multiple databases were searched for both clinical and basic science laboratory studies on hip capsule innervation. Non-innervation capsule and non-human animal studies were excluded. Macroscopic and microscopic differences in capsular innervation between normal hips, and hips with OA, FAI, and DDH were analyzed. Methodological quality assessment of all studies included in this review was completed using the Methodological Index for Non-randomized Studies.

Results

Ten articles were analyzed (263 specimens; 211 patients, 52 cadavers; mean Methodological Index for Non-randomized Studies 10/16). The hip capsule is innervated by the sciatic and superior gluteal nerves posterosuperiorly, nerve to quadratus femoris and inferior gluteal nerve posteroinferiorly, and femoral and obturator nerves anteriorly. The anterior-superior capsule between 1:00 and 2:30 o’clock on a right hip is a safe internervous zone. The superolateral capsule has the greatest density of mechanoreceptors and sensory fibers. OA is associated with a greater expression of nerve fibers compared with normal hips but does not correlate with pain or disability. No significant differences were found in nerve fiber expression among patients with DDH, FAI, or normal hips. A negative correlation is seen with aging and pain fiber expression.

Conclusions

The hip capsule has a complex macroscopic and microscopic innervation pattern with varying nerve fiber expression from at least 6 separate peripheral nerves. OA is associated with a greater expression of nerve fibers, although nerve fiber expression does not correlate with painful pathology.

Level of Evidence

IV, Systematic review of level I-IV studies.

Genetic variant of COL11A2 gene is functionally associated with developmental dysplasia of the hip in Chinese Han population

OBJECTIVES

Developmental dysplasia of the hip (DDH) is a common skeletal disorder. This study was conducted to demonstrate the association between DDH and a polymorphism rs9277935 of COL11A2 gene.

RESULTS

A significant difference in genotype distribution in a recessive model (TT+GT vs. GG) between two groups (P=0.017) was demonstrated. Analysis in female patients showed significantly greater frequency of minor allele G(0.49 vs. 0.43, p=0.024) and significantly higher distribution of GG genotype (p=0.006). DDH patients were found to have significantly lower COL11A2 expression than controls. Moreover, DDH patients with rs9277935 genotype TT have a significantly increased expression of COL11A2 than those with genotype GG. COL11A2 demonstrated chondrogenic properties in vitro.

CONCLUSION

Polymorphism rs9277935 of gene COL11A2 is a functional variant regulating the expression and the chondrogenic properties of COL11A2 in DDH in Chinese Han population.

METHODS

A case-control candidate gene association study was conducted in 945 patients (350 radiologically confirmed DDH patients and 595 healthy controls). Difference of COL11A2 expression in hip joint tissue was compared between the patients and the controls. Allelic difference in Col11a2 expression by rs9277935 was assessed with luciferase activity. Chondrogenic effects of Col11a2 signaling on BMSCs were also determined in vitro.

Management of Hip Disorders in Patients with Cerebral Palsy

Hip disorders are the second most common musculoskeletal abnormality seen in children with cerebral palsy, affecting nearly 1 in 3. The goal of surgical intervention is to provide a mobile, located, and painless hip. Reconstructive procedures are indicated for children with migration percentages of >40%. Reconstructive procedures typically result in a long-term satisfactory outcome, although recurrence is seen particularly in nonambulatory children and when the reconstruction is performed earlier than 6 years of age. Salvage procedures are performed when reconstructive procedures are no longer an option and degenerative changes have occurred. They include proximal femoral valgus osteotomy, proximal femoral resection, and hip arthroplasty.

Innervation of the hip joint capsular complex: A systematic review of histological and immunohistochemical studies and their clinical implications for contemporary treatment strategies in total hip arthroplasty

The hip joint capsule contributes to the stability of the hip joint and lower extremity, yet this structure is incised and often removed during total hip arthroplasty (THA). Increasing incidence of osteoarthritis is accompanied by a dramatic rise in THAs over the last few decades. Consequently, to improve this treatment, THA with capsular repair has evolved. This partial restoration of physiological hip stability has resulted in a substantial reduction in post-operative dislocation rates compared to conventional THA without capsular repair. A further reason for the success of this procedure is thought to be the preservation of the innervation of the capsule. A systematic review of studies investigating the innervation of the hip joint capsular complex and pseudocapsule with histological techniques was performed, as this is not well established. The literature was sought from databases Amed, Embase and Medline via OVID, PubMed, ScienceDirect, Scopus and Web of Science; excluding articles without a histological component and those involving animals. A total of 21 articles on the topic were identified. The literature indicates two primary outcomes and potential clinical implications of the innervation of the capsule. Firstly, a role in the mechanics of the hip joint, as mechanoreceptors may be present in the capsule. However, the nomenclature used to describe the distribution of the innervation is inconsistent. Furthermore, the current literature is unable to reliably confirm the proprioceptive role of the capsule, as no immunohistochemical study to date has reported type I-III mechanoreceptors in the capsule. Secondly, the capsule may play a role in pain perception, as the density of innervation appears to be altered in painful individuals. Also, increasing age may indicate requirements for different strategies to surgically manage the hip capsule. However, this requires further study, as well as the role of innervation according to sex, specific pathology and other morphometric variables. Increased understanding may highlight the requirement for capsular repair following THA, how this technique may be developed and the contribution of the capsule to joint function and stability.

Parents and Physiotherapists Recognition of Non-Verbal Communication of Pain in Individuals with Cerebral Palsy

Pain assessment is difficult in individuals with cerebral palsy (CP). This is of particular relevance in children with communication difficulties, when non-verbal pain behaviors could be essential for appropriate pain recognition. Parents are considered good proxies in the recognition of pain in their children; however, health professionals also need a good understanding of their patients' pain experience. This study aims at analyzing the agreement between parents' and physiotherapists' assessments of verbal and non-verbal pain behaviors in individuals with CP. A written survey about pain characteristics and non-verbal pain expression of 96 persons with CP (45 classified as communicative, and 51 as non-communicative individuals) was performed. Parents and physiotherapists displayed a high agreement in their estimations of the presence of chronic pain, healthcare seeking, pain intensity and pain interference, as well as in non-verbal pain behaviors. Physiotherapists and parents can recognize pain behaviors in individuals with CP regardless of communication disabilities.

Effect of Hip Reconstructive Surgery on Health-Related Quality of Life of Non-Ambulatory Children with Cerebral Palsy

BACKGROUND

The primary aim of this study was to evaluate the relationship of the migration percentage (a radiographic metric quantifying hip displacement) in children with Gross Motor Function Classification System (GMFCS) level-IV or V cerebral palsy and spastic hip dysplasia to the acetabular index and the health-related quality of life (HRQOL) as measured with the Caregiver Priorities and Child Health Index of Life with Disabilities (CPCHILD) before and after reconstructive hip surgery.

METHODS

In a prospective cohort study (n = 38), the migration percentage, acetabular index, and CPCHILD scores were analyzed using the Pearson correlation analysis immediately before reconstructive hip surgery and at 6 weeks and 3, 6, 12, and 24 months after the surgery. Subgroup analysis was used to compare patients who had a preoperative migration percentage of ≥50% with those who had a preoperative migration percentage of <50% and to compare the acetabular index between patients who had a pelvic osteotomy and those who had not. Linear mixed models were used to analyze changes in the migration percentage, acetabular index, and CPCHILD scores over time.

RESULTS

The preoperative migration percentage negatively correlated with the preoperative CPCHILD score (r = -0.50; p = 0.002). This relationship continued throughout the follow-up period such that, for each additional 1% correction in migration percentage, the CPCHILD total score increased by 0.2 point (p < 0.001). There was no correlation between the acetabular index and CPCHILD total score before or after surgery (p = 0.09 to 0.71). The preoperative CPCHILD total scores differed between the migration-percentile groups (mean difference = 13 points; 95% confidence interval = 3.3 to 22.8; p = 0.01). However, after hip surgery, the CPCHILD score improved similarly for both groups.

CONCLUSIONS

These data support the effectiveness of reconstructive hip surgery for the treatment of spastic hip dysplasia to improve the HRQOL of non-ambulatory children with severe cerebral palsy.

LEVEL OF EVIDENCE

Prospective Level IV. See Instructions for Authors for a complete description of levels of evidence.