Head-shaft angle is a risk factor for hip displacement in children with cerebral palsy

Background and purpose — Hip dislocation in children with cerebral palsy (CP) is a common and severe problem. The Swedish follow-up program for CP (CPUP) includes standardized monitoring of the hips. Migration percentage (MP) is a widely accepted measure of hip displacement. Coxa valga and valgus of the femoral head in relation to the femoral neck can be measured as the head-shaft angle (HSA). We assessed HSA as a risk factor for hip displacement in CP.

Patients and methods — We analyzed radiographs of children within CPUP from selected regions of Sweden. Inclusion criteria were children with Gross Motor Function Classification System (GMFCS) levels III–V, MP of < 40% in both hips at the first radiograph, and a follow-up period of 5 years or until development of MP > 40% of either hip within 5 years. Risk ratio between children who differed in HSA by 1 degree was calculated and corrected for age, MP, and GMFCS level using multiple Poisson regression.

Results — 145 children (73 boys) with a mean age of 3.5 (0.6–9.7) years at the initial radiograph were included. 51 children developed hip displacement whereas 94 children maintained a MP of < 40%. The risk ratio for hip displacement was 1.05 (p < 0.001; 95% CI 1.02–1.08). When comparing 2 children of the same age, GMFCS level, and MP, a 10-degree difference in HSA results in a 1.6-times higher risk of hip displacement in the child with the higher HSA.

Interpretation — A high HSA appears to be a risk factor for hip displacement in children with CP.     

The Impact of Spinal Fusion on Hip Displacement in Cerebral Palsy

Background and study aimsThe aims of this study were to determine the risk of progressive hip subluxation in children with CP after spinal fusion for scoliosis and how frequent the hips follow-up should be scheduled.Patients and methodsPelvis radiography [migration index (MI) and pelvic obliquity (PO)] of Gross Motor Function Classification System (GMFCS) levels IV and V children with CP who received spinal fusion and pelvic fixation were reviewed retrospectively. This population was categorized into three groups based on the MI at spinal fusion: G1 = 0–29%; G2 = 30–59%; and G3 = 60–100%.ResultsFifty children (age 7.5–15.0 years) and categorized into 3 groups (G1 = 19, G2 = 23, G3 = 8; 100 hips in total). Preoperative and last follow-up MI were 22 ± 7% and 30 ± 20% (G1), 41 ± 9% and 43 ± 22% (G2), 92 ± 15% and 97 ± 10% (G3). The MIs at spinal fusion between groups were statistically different (p < 0.001). In G1, the mean MI progression was 5% and 25% at 12 months and 62 months, respectively. In G2, the mean MI progression was 9% and 25% at 12 months and 32 months, respectively. The progression more than 10% occurred within 2 years in G1 and within 1 year in G2. There was no difference between groups based on preoperative degree of PO (p = 0.653) and correction rate in PO (p = 0.421).ConclusionsIn GMFCS IV and V children with the highest risk for progression occurred with increasing preoperative MI, especially over 50%. Hips should be monitored continuously after spinal fusion until hip stability is documented.     

Percutaneous pelvic osteotomy in cerebral palsy patients: Surgical technique and indications

AIM: To describe the surgical technique of and indications for percutaneous pelvic osteotomy in patients with severe cerebral palsy.METHODS: Twenty-one non-ambulatory children and adolescents (22 hips) were consecutively treated with percutaneous pelvic osteotomy, which was used in conjunction with varus, derotational, shortening femoral osteotomy and soft tissue release, to correct progressive hip subluxation and acetabular dysplasia. The age, gender, Gross Motor Function Classification System level, side(s) of operated hip, total time of follow-up, immediate post-operative immobilization, complications, and the need for revision surgery were recorded for all patients.RESULTS: Seventeen patients (81%) were classified as GMFCS level IV, and 4 (19%) patients were classified as GMFCS level V. At the time of surgery, the mean age was 10.3 years (range: 4-15 years). The mean Reimers’ migration percentage improved from 63% (range: 3%-100%) pre-operatively to 6.5% (range: 0%-70%) at the final follow-up (P < 0.05). The mean acetabular angle (AA) improved from 34.1° (range: 19°-50°) pre-operatively to 14.1° (range: 5°-27°) (P < 0.05). Surgical correction of MP and AA was comparable in hips with open (n = 14) or closed (n = 8) triradiate cartilage (P < 0.05). All operated hips were pain-free at the time of the final follow-up visit, although one patient had pain for 6 mo after surgery. We did not observe any cases of bone graft dislodgement or avascular necrosis of the femoral head.CONCLUSION: Pelvic osteotomy through a less invasive surgical approach appears to be a valid alternative with similar outcomes to those of standard techniques. This method allows for less muscle stripping and blood loss and a shorter operating time.     

Hip Displacement in Cerebral Palsy: The Role of Surveillance

IntroductionHip displacement is common in cerebral palsy (CP) and is related to the severity of neurological and functional impairment. It is a silent, but progressive disease, and can result in significant morbidity and decreased quality of life, if left untreated. The pathophysiology of hip displacement in CP is a combination of hip flexor-adductor muscle spasticity, abductor muscle weakness, and delayed weight-bearing, resulting in proximal femoral deformities and progressive acetabular dysplasia. Due to a lack of symptoms in the early stages of hip displacement, the diagnosis is easily missed. Awareness of this condition and regular surveillance by clinical examination and serial radiographs of the hips are the key to early diagnosis and treatment.Hip surveillance programmesSeveral population-based studies from around the world have demonstrated that universal hip surveillance in children with CP allows early detection of hip displacement and appropriate early intervention, with a resultant decrease in painful dislocations. Global hip surveillance models are based upon the patients’ age, functional level determined by the Gross Motor Function Classification system (GMFCS), gait classification, standardized clinical exam, and radiographic indices such as the migration percentage (MP), as critical indicators of progressive hip displacement.ConclusionDespite 25 years of evidence showing the efficacy of established hip surveillance programmes, there is poor awareness among healthcare professionals in India about the importance of regular hip surveillance in children with CP. There is a need for professional organizations to develop evidence-based guidelines for hip surveillance which are relevant to the Indian context.     

Hip displacement in relation to age and gross motor function in children with cerebral palsy

Purpose

Hip dislocation in cerebral palsy (CP) is a serious complication. By radiographic screening and prophylactic surgery of children at risk most dislocations can be prevented. CPUP, the Swedish CP registry and follow-up program, includes annual radiographic examinations of children at Gross Motor Function Classification System (GMFCS) levels III–V. Data from CPUP were analysed to assess the risk of hip displacement in relation to GMFCS levels and age.

Methods

All children at GMFCS levels III–V (N = 353) whose first radiographic screening occurred before 3 years of age were followed between the ages 2–7 years. Migration percentages (MPs) were recorded annually (1,664 pelvic radiographs) and analysed using discrete time survival analysis.

Results

The risk of hip displacement between 2 years and 7 years of age was significantly (p < 0.05) higher for children at GMFCS level V during the entire study period. The risk was highest at 2–3 years of age and decreased significantly (p < 0.001) with each year of age (OR = 0.71, 95 % CI 0.60–0.83). The cumulative risk at age 7 years for those at GMFCS V for MP ≥ 40 % was 47 % (95 % CI 37–58). The corresponding risk at GMFCS IV was 24 % (16–34) and at GMFCS III 23 % (12–42).

Conclusions

Children at GMFCS V have a significantly higher risk of hip displacement compared with children at GMFCS III–IV. The risk is highest at 2–3 years of age. The results support a surveillance program including radiographic hip examinations as soon as the diagnosis of severe CP is suspected.     

Total Hip Replacement in Sickle Cell Disease Patients with Avascular Necrosis of Head of Femur: A Retrospective Observational Study

BackgroundFemoral head avascular necrosis leads to osteoarthritis of the hip joint and affects its functional capacity in sickle cell disease patients. The functional outcomes of total hip replacement (THR) on patients with congruous joints who underwent hip replacement after having a failed joint preservation surgery are unknown. This study aimed to compare the functional outcomes of THR in patients with sickle cell disease having avascular necrosis with and without loss of hip joint congruency.MethodsThis retrospective study included 35 patients (age, 20–52 years; 18 males and 17 females) who underwent uncemented THR. Patients were divided into Group-A (n = 18, good hip joint congruency) and Group-B (n = 17, obliterated hip joint congruency). The Harris Hip Score (HHS) was used to assess functional outcomes. All patients were followed up at 6-weekly intervals then 6-monthly intervals.ResultsThe mean follow-up period was 8.26 ± 3.01 years. The mean preoperative HHSs of Group-A and Group-B were 45.22 ± 3.021 and 25.94 ± 4.437, respectively. Postoperatively, a subsequent increase in HHS was found in both groups, and a significant difference between the groups was observed at 6 weeks (p < 0.0001*) and 1 year (p < 0.0006*). Interestingly, HHS was not significantly different (p = 0.0688) at 5-year follow-up between the groups. The differences in HHS within the group at each subsequent follow-up were also statistically significant (ANOVA, p < 0.0001*).ConclusionA significant improvement was observed with THR in both groups. Nevertheless, the flattened hip joint congruency group showed significantly better HHS improvements than the normal congruency groups. These findings may aid in the decision-making capabilities of the surgeons.     

The impact of asymmetry on the radiographical outcomes following hip reconstruction in patients with cerebral palsy

Purpose:The purpose of this study was to evaluate the impact of asymmetric hip dysplasia on the outcome of hip reconstruction in patients with cerebral palsy according to preoperative migration percentage (MP).Methods:This study was institutional review board-approved for retrospective cohort review. From 2008 to 2018, 65 patients met inclusion criteria: Gross Motor Function Scale Classification (GMFSC) III to V with spastic hips (MP > 30%) who underwent bilateral hip reconstruction, with a follow-up > 24 months. Main exclusion criteria: children with associated syndromes or chromosomal disorders. The cohort was subdivided into three groups according to preoperative MP difference between hips: Group A > 50%, group B 20% to 50% and Group C < 20%. Subsequently, the groups were analyzed individually and then compared. The asymmetry of extended abduction of the hip was also evaluated and separated into three groups: no asymmetry (< 20° difference), mild asymmetry (20° to 50° difference) and severe (> 50° difference).Results:In total, 65 patients underwent bilateral bony reconstructive surgery (130 hips). Mean age at surgery was 10.1 years (sd 3.6; 3.6 to 18.4). Mean age at follow-up was 14.7 years (sd 3.8; 8 to 21). Preoperative GMFSC distribution was grade III (four, 6%), IV (15, 23%) and V (46, 71%). In all, 21 symmetric hips (< 20% MP difference) had a preoperative MP difference of 9% and a follow-up MP difference of 18% (p > 0.05); 32 had a preoperative MP difference of 34% and a follow-up MP difference of 16% (p < 0.0001); 12 had a preoperative MP difference of 80% and a follow-up difference of 6% (p < 0.0001). According to pre- and postoperative abduction values, the mean high hip abduction preoperatively was 34° (sd 17°), whereas low hip abduction was 23° (sd 17°).Conclusion:Hips with asymmetrical dysplasia and/or abduction undergoing bilateral reconstructive surgery focused on symmetric abduction, and corrected dysplasia in patients with cerebral palsy has improved symmetry in hip abduction and MP. Obtaining this goal immediately postoperatively is maintained to medium-term follow-up.Level of Evidence:IV     

Hip reconstruction is more painful than spine fusion in children with cerebral palsy

PurposeConcerns about pain control in patients with cerebral palsy (CP) are especially anxiety provoking for parents, given the fact that spasticity, communication issues, and postoperative muscle spasms are significant problems that make pain control difficult in these patients. A better understanding of the magnitude and quality of the pain these patients experience after our surgical procedures would better prepare the patients and their families. The purpose of this study is to quantify the amount of postoperative pain in children with CP undergoing hip reconstruction and spinal fusion. Specifically, the study will compare pain scores and the amount of narcotics used between the two groups.ResultsForty-two patients with CP who underwent hip reconstruction (mean age 8.8 years) were compared to 26 patients who underwent PSF (mean age 15.4 years). The total opioid used, normalized by body weight and by days length of stay (DLOS), in the hip group was 0.49 mg morphine/kg/DLOS, compared to 0.24 for the spine group (p = 0.014). The mean pain score for the hip group was 1.52, compared to 0.72 for the spine group (p = 0.013). There were no significant differences in the occurrence of adverse effects related to pain management between the two groups.ConclusionPatients with CP undergoing hip reconstruction surgery had significantly more pain, as exhibited by requiring more narcotics and having higher pain scores, than those patients undergoing PSF. The knowledge that hip reconstruction is more painful than PSF for patients with CP will better prepare families about what to expect in the postoperative period and will alert providers to supply better postoperative pain control in these patients.

Level of evidence

III (case control series).     

There is No Link Between Birth Weight and Developmental Dysplasia of the Hip

AimsDevelopmental Dysplasia of the Hip (DDH) has been linked to high birth weight and packaging disorders, though the evidence is limited. This has implications on screening strategies. The aim of this study was to establish whether birth weight was truly associated with the incidence of DDH.Patients and MethodsThis cohort study analysed the birth weights of all babies born at our institution over a 24 month period, between 01/01/2017 and 01/01/2019. Babies with DDH and those without DDH were compared. Babies were excluded if born before 38 weeks, had incomplete data or were a non-singleton pregnancy. Sub-analysis was performed for DDH severity (dysplastic versus subluxed/dislocated hips), breech presentation, gestational age, gender and ethnicity. Statistical analysis was performed using SPSS.ResultsThere were 10,113 babies born at our institution during the selected timeframe, of which 884 were excluded for prematurity, 336 for being non-singleton and 19 for incomplete data. This left 8874 for analysis, of which 95 babies had confirmed DDH. Both the Non-DDH and DDH data sets had normal distribution (Shapiro-Wilkes, p = 0.308 and 0.629, respectively), with mean birth weights of 3477.7 g with DDH and 3492.8 g without DDH. No difference in birth weight was found (Independent T test, p = 0.789). Females had a lower birth weight than males (3293.1 g versus 3416.6 g (p < 0.001)) yet have a higher incidence of DDH (ratio 6:1 in this dataset). No significant difference was found between birth weights of females with and without DDH (p = 0.068), nor between males with and without DDH (p = 0.513). There were no significant differences in birth weights even when only displaced hips were analysed (p = 0.543), nor according to breech presentation (p = 0.8). Longer gestation babies weighed more (p < 0.00001), yet showed no increase in DDH incidence (p = 0.64).ConclusionThis study discredits the belief that DDH may be related to higher birth weight, thus casting doubt on the link to DDH being a packaging problem in utero. This, therefore, allows future research to prioritise the investigation of alternative aetiologies.     

The Development of Leg Length Difference and Influence on Persistent Dysplasia in Patients with Developmental Dysplasia of the Hip

IntroductionLeg-length difference (LLD) is common in patients with developmental dysplasia of the hip (DDH). LLD of > 1 cm at skeletal maturity is reported in > 40% of patients, with the majority related to ipsilateral overgrowth. A longer DDH leg might lead to excessive mechanical loading at the acetabular margin, resulting in compromised acetabular development. We hypothesised that the LLD would negatively influence acetabular development. If so, it would be advantageous to identify such patients early in the course of follow-up, and address this if necessary.MethodsA retrospective study was conducted on a consecutive series of DDH patients managed surgically at the Royal National Orthopaedic Hospital, Stanmore, United Kingdom. We included patients with adequate long-leg radiographs at the age of 4–8 years (early-FU) and skeletal maturity (final-FU). Bilateral cases and those who underwent surgical procedures for hip dysplasia during the follow-up period were excluded. Measurements including leg length and centre-edge-angle (CE-angle) were obtained at the 2 time points.ResultsTwenty-seven patients were included, mean age at early-FU 5.7 (± 0.9) years, and 13.9 (± 1.0) years at final-FU. Mean LLD at early-FU was 9.5 (± 7.6) mm and 10.9 (± 9.4) mm at final-FU, p = 0.337. Correlation between early- and final-FU LLD was 0.68 (p < 0.001). The mean CE-angle at early follow-up was 14.6° (± 9.8), this improved to 23.2° (± 8.2) at skeletal maturity (p = 0.003, paired samples t-test). Linear regression analysis showed a non-significant trend towards less CE-angle improvement in patients with more initial residual dysplasia and more initial LLD.ConclusionMost leg-length differences can be identified early in the follow-up period, nevertheless, considerable individual changes in LLD are observed on continued follow-up. Furthermore, a trend was observed towards impaired acetabular improvement in patients with more LLD. These findings justify careful clinical and radiological monitoring of LLD from an early stage in the follow-up period.Supplementary InformationThe online version contains supplementary material available at 10.1007/s43465-021-00492-5.     

Restoring Rotation Center in Total Hip Arthroplasty for Developmental Dysplasia of the Hip with the Assistance of Three Dimensional Printing Technology: A Pilot Study

ObjectiveTo develop a new method to restore hip rotation center exactly and rapidly in total hip arthroplasty (THA) with the assistance of three dimensional (3D) printing technology and evaluate its clinical and radiological outcomes.MethodsFrom March 2014 to July 2018, a total of 17 patients (five hips of four men and 16 hips of 13 women) with end‐stage osteoarthritis secondary to developmental dysplasia of the hip who underwent THA were analyzed and followed up retrospectively. The average age is 58.00 ± 8.12 years (range from 45 to 71 years). Simulated operations were performed on 3D printed hip models for preoperative planning. The morphology of Harris fossa and acetabular notches were recognized and restored to locate the acetabular center. The size of bone defect was measured by the bone wax method. The agreement on the size of acetabular cup and bone defect between simulated operations and actual operations were analyzed. Harris Hip Score (HHS) was used to evaluate the recovery of hip joint function. The vertical distance and horizontal distance of the rotation center on the pelvis plain radiograph were measured, which were used to assess the efficacy of restoring hip rotation center and acetabular cup migration.ResultsThe mean sizes of bone defect in simulated operations and THA were 4.58 ± 2.47 cm² and 4.55 ± 2.57 cm² respectively. There was no significant difference statistically between the sizes of bone defect in simulated operations and the actual sizes of bone defect in THA (t = 0.03, P = 0.97). The sizes of the acetabular cup of simulated operations on 3D print models showed a high rate of coincidence with the actual sizes in the operations (ICC = 0.93). All 17 patients were available for clinical and radiological follow‐up. The average follow‐up time was 18.35 ± 6.86 months (range, 12–36 months. The average HHS of the patients was improved from (38.33 ± 6.07) preoperatively to the last follow‐up (88.61 ± 3.44) postoperatively. The mean vertical and horizontal distances of hip rotation center on the pelvic radiographs were restored to 15.12 ± 1.25 mm and 32.49 ± 2.83 mm respectively. No case presented dislocation or radiological signs of loosening until last follow‐up.ConclusionsThe application of 3D printing technology facilitates orthopedists to recognize the morphology of Harris fossa and acetabular notches, locate the acetabular center and restore the hip rotation center rapidly and accurately.     

Core Decompression Prevents Progression of Asymptomatic Type C Osteonecrosis of Femoral Head According to the Japanese Investigation Committee Classification: A Retrospective Study

ObjectiveTo evaluate whether core decompression could prevent progression of asymptomatic type C osteonecrosis of the femoral head (ONFH) according to the Japanese Investigation Committee (JIC) classification.MethodsThis retrospective cohort study included 124 hips (117 patients) with asymptomatic type C ONFH. Seventy‐one hips (67 patients) received core decompression (core decompression group) and 53 hips (50 patients) received no surgical treatment (control group). Clinical and radiological follow‐up was conducted at 6 and 12 months, then annually until 5 years. Clinical outcomes were evaluated in terms of the Oxford hip score and UCLA Activity Level rating. Radiological outcomes were evaluated using X‐ray and magnetic resonance imaging. Survival analysis was performed based on collapse of the femoral head as the first endpoint and total hip arthroplasty (THA) as the second endpoint.ResultsThere were no significant differences in clinical outcomes between the core decompression group and the control group within 2 years after surgery. Patients in the core decompression group had significantly better Oxford hip score and UCLA Activity Level from year 3 to the end of follow‐up (P < 0.05). In year 5, the absolute difference in Oxford hip score (5.3 points) exceeded the reported minimal clinically important difference (MCID, 5.2 points). In years 3–5, the absolute difference in UCLA Activity Level rating (0.95 points, 0.95 points, and 0.99 points, respectively) exceeded the reported MCID (0.92 points). By 5‐year follow‐up, significantly fewer patients in the core decompression group had experienced femoral head collapse (40.8% vs 62.3%, P = 0.011) or received THA (26.8% vs 45.3%, p = 0.022).ConclusionsCore decompression can prevent progression of asymptomatic type C ONFH according to the JIC classification, leading to better medium‐term hip function and activity levels than no surgical treatment. Core decompression is recommended for early intervention against asymptomatic type C ONFH.     

The effect of hip reconstruction on gross motor function levels in children with cerebral palsy

Objective

The aim of this study was to determine whether the hip reconstruction has an effect on gross motor function classification system (GMFCS) levels in patients with hip instability in cerebral palsy (CP).

Deformities of proximal femur in spastic hip displacement: A reconstructed three-dimensional computed tomography model approach

Background/PurposeSpastic hip displacement is a common musculoskeletal problem in cerebral palsy (CP), leading to further complications in daily life. Deformities of the proximal femur were regarded as a factor in hip displacement, and therefore, femoral osteotomy is often recommended. This study aims to identify the relationship between hip displacement and femoral deformities.MethodsWe retrospectively collected preoperative radiography and three-dimensional computed tomography (3D-CT) images from 19 nonambulatory CP children with unilateral hip displacement (average age: 8.4 years; range: 4.4–13.6). The 3D image of femur was reconstructed for measuring the femur anteversion angle (FAA) and true femoral neck-shaft angle (NSA). The association among migration percentage (MP), acetabular index (AI), FAA, and NSA between nondisplaced and displaced hips was analyzed by paired t test and its correlations were identified.ResultsThe FAA and AI are significantly greater in displaced hips (42.7° vs. 36.3° and 32.8° vs. 22.7°, respectively, p < 0.001). However, the NSA is similar between displaced and nondisplaced hips. The AI and FAA have significantly positive correlations with MP between nondisplaced hips and displaced hips (0.69 and 0.57, respectively).ConclusionUsing reconstructed 3D-CT images we can directly measure and prove these femoral deformities. We found that AI has a positive correlation with MP (0.69), which is consistent with the results of previous studies. The displaced side has greater femur anteversion (42.7° vs. 36.3°), and coxa valga is common in these nonambulatory patients, irrespective of whether or not these patients underwent hip displacement. In addition, the severity of AI and anteversion angle will be affected by the MP.     

Relook into the Risk Factors of Proximal Junctional Kyphosis in Early Onset Scoliosis Patients: Does the Location of Upper Instrumented Vertebra in Relation to the Sagittal Apex Matter?

ObjectiveGrowing rods surgery is the mainstay of treatment for early‐onset scoliosis (EOS) while proximal junctional kyphosis (PJK) is one of the most commonly reported postoperative complications. We sought to investigate the impact of the location of upper instrumented vertebra (UIV) in relation to the sagittal apex on proximal junctional kyphosis in EOS after traditional growing rods (GRs) treatment.MethodsA total of 102 EOS patients who received traditional growing rods treatment with a follow‐up of at least 2 years between 2009 and 2020 were retrospectively reviewed. Radiographic measurements were performed before and after the index surgery and at the latest follow‐up. We investigated the coronal Cobb angle and spinopelvic parameters of the whole spine. The location of the UIV, apex, lower instrumented vertebra (LIV), inflection vertebra (IV), the number and distance of UIV‐apex, LIV‐apex and IV‐apex were also recorded. Risk factors for PJK were analyzed by logistic regression analysis.ResultsPJK was observed in 21 patients (20.6%) during the follow‐up period. The PJK group showed a younger age at the index surgery (5.9 vs. 7.1 years, P = 0.042), more lengthening procedure times (5.0 vs. 4.0, P = 0.032), larger preoperative coronal Cobb angle (82.0 vs. 75.6°, P = 0.038), higher correction rate (51.2% vs. 44.4%, P = 0.047) and larger postoperative proximal junctional angle (PJA) (13.9 vs. 5.5°, P < 0.001) than the non‐PJK group. The ratio of the number and distance from UIV‐apex to IV‐apex also differed significantly between the two groups. The logistic regression revealed that age at the index surgery ≤ 7 years, the ratio of the number from UIV‐ apex to IV‐ apex ≤ 0.6 and the ratio of the distance from UIV‐ apex to IV‐ apex ≤ 0.6 were independent risk factors for postoperative PJK.ConclusionBesides younger age, a closer location of UIV relative to the sagittal apex is identified to be an independent risk factor of postoperative PJK. Selection of UIV at a relatively farther location away from the sagittal apex might help prevent occurrence of PJK.     

Can the Femoro-Epiphyseal Acetabular Roof (FEAR) Index Be Used to Distinguish Dysplasia from Impingement?

BackgroundClassifying hips with structural deformity on the spectrum from impingement to dysplasia is often subjective and frequently inexact. Currently used radiographic measures may inaccurately predict a hip’s morphological stability in borderline hips. A recently described radiographic measure, the Femoro-Epiphyseal Acetabular Roof (FEAR) index, has demonstrated an ability to predict stability in the borderline hip. This measure is attractive to clinicians because procedures can be used on the basis of a hip’s pathomechanics. This study was designed to further validate and characterize the FEAR index in a skeletally immature population, in hips with dysplasia/femoroacetabular impingement (FAI), and in asymptomatic hips.Questions/purposes(1) What are the characteristics of the FEAR index in children and how does the index change with skeletal maturation? (2) How does the FEAR index correlate with clinical diagnosis and surgical treatment in a large cohort of symptomatic hips and asymptomatic controls? (3) How does the FEAR index correlate with clinical diagnosis in the borderline hip (lateral center-edge angle [LCEA] 20°-25°) group?MethodsA total of 220 participants with symptomatic investigational hips with a clinical diagnosis of dysplasia or FAI between January 2008 and January 2018 were retrospectively collected from the senior author’s practice. Investigational hips were excluded if they had any femoral head abnormalities preventing LCEA measurement (for example, Perthes disease), Tönnis osteoarthritis grade greater than 1, prior hip surgery, or prior femoral osteotomy. In the 220 participants, 395 hips met inclusion criteria. Once exclusion criteria were applied, 15 hips were excluded due to prior hip surgery or prior femoral osteotomy, and 12 hips were excluded due to femoral head deformity. A single hip was then randomly selected from each participant, resulting in 206 investigational hips with a mean age of 13 ± 3 years. Between January 2017 and December 2017, 70 asymptomatic control participants were retrospectively collected from the senior author’s institutional trauma database. Control hips were included if the AP pelvis film had the coccyx centered over the pubic symphysis and within 1 to 3 cm of the superior aspect of the symphysis. Control hips were excluded if there was any fracture to the pelvis or ipsilateral femur or the participant had prior hip/pelvis surgery. After exclusion criteria were applied, 16 hips were excluded due to fracture. One hip was then randomly selected from each participant, resulting in 65 control hips with a mean age of 16 ± 8 years. Standardized standing AP pelvis radiographs were used to measure the FEAR index, LCEA, and Tönnis angle in the investigational cohort. Standardized false-profile radiographs were used to measure the anterior center-edge angle (ACEA) in the investigational cohort. Two blinded investigators measured the FEAR index with an intraclass correlation coefficient of 0.92 [95% CI 0.84 to 0.96]. Question 1 was answered by comparing the above radiographic measures in age subgroups (childhood: younger than 10 years; adolescence: 10 to 14 years old; maturity: older than 14 years) of dysplastic, FAI, and control hips. Question 2 was answered by comparing the radiographic measures in all dysplastic, FAI, control hips, and a subgroup of operatively or nonoperatively managed dysplasia and FAI hips. Question 3 was answered by comparing the radiographic measures in borderline (LCEA 20°-25°) dysplastic, FAI, and control hips.ResultsThe FEAR index was lower in older dysplastic of hips (younger than 10 years, 6° ± 9°; 10 to 14 years, 4° ± 10°; older than 14 years, 5° ± 9°; p < 0.001) and control hips (younger than 10 years, -6° ± 5°; 10 to 14 years, -15° ± 4°; older than 14 years, -16° ± 7°; p < 0.001). The diagnosis and age groups were independently correlated with the FEAR index (p < 0.001). The relationship between the FEAR index and diagnosis remained consistent in each age group (p = 0.11). The FEAR index was higher in all dysplastic hips (mean 5° ± 10°) than in asymptomatic controls (mean -13° ± 7°; p < 0.001) and FAI hips (mean -10° ± 11°; p < 0.001). Using -1.3° as a cutoff for FAI/control hips and dysplastic hips, 81% (112 of 139) of hips with values below this threshold were FAI/control, and 89% (117 of 132) of hips with values above -1.3° were dysplastic. The receiver operator characteristics area under the curve (ROC-AUC) was 0.91. Similarly, the FEAR index was higher in borderline dysplastic hips than in both asymptomatic borderline controls (p < 0.001) and borderline FAI hips (p < 0.001). Eighty-nine percent (33 of 37) of hips with values below this threshold were FAI/control, and 90% (37 of 41) of hips with values above -1.3° were dysplastic. The ROC-AUC for borderline hips was 0.86.ConclusionThe FEAR index was associated with the diagnosis of hip dysplasia and FAI in a patient cohort with a wide age range and with varying degrees of acetabular deformity. Specifically, a FEAR index greater than -1.3° is associated with a dysplastic hip and a FEAR index less than -1.3° is associated with a hip displaying FAI. Using this reliable, developmentally based radiographic measure may help hip preservation surgeons establish a correct diagnosis and more appropriately guide treatment.Level of Evidence LevelIII, diagnostic study.     

Caput valgum associated with developmental dysplasia of the hip: management by transphyseal screw fixation

Purpose

A late finding of some hips treated for developmental dysplasia of the hip (DDH) is a growth disturbance of the lateral proximal femoral physis, which results in caput valgum and possibly osteoarthritis. Current treatment options include complete epiphysiodesis of the proximal femoral physis or a corrective proximal femoral osteotomy. Alternatively, a transphyseal screw through the inferomedial proximal femoral physis that preserves superolateral growth might improve this deformity.

Methods

This study evaluates the effect of such a transphyseal screw on both femoral and acetabular development in patients with caput valgum following open treatment of DDH. These patients were followed clinically and radiographically until skeletal maturity. Preoperative and postoperative radiographs were assessed, measuring the proximal femoral physeal orientation (PFPO), the head–shaft angle (HSA), Sharp’s angle and the center edge angle of Wiberg (CE angle).

Results

Thirteen hips of 11 consecutive patients were followed prospectively. The age at the time of transphyseal screw placement was between 5 and 14 years. The mean improvement of the PFPO and HSA was 14° (p < 0.01) and 11° (p < 0.001), respectively. The mean improvement of Sharp’s angle and CE angle was 4.7° (p < 0.01) and 5.8° (p < 0.02), respectively. Five patients underwent screw revision.

Conclusions

A transphyseal screw across the proximal femoral physis improved the proximal femur and acetabular geometry.     

Learning Curve of Total Hip Arthroplasty in Direct Anterior Approach without Requiring Corrective Osteotomy for Hip Dysplasia

ObjectiveTo explore the learning curve of total hip arthroplasty in direct anterior approach (DA‐THA) without requiring corrective osteotomy for patients with unilateral developmental dysplasia of the hip (DDH) through the evaluation of clinical and radiographic results.MethodFrom December 2015 to January 2021, we retrospectively evaluated a surgeon''s first 100 patients with unilateral hip dysplasia (Crowe I‐III) who underwent DA‐THA. All procedures were performed by a fellowship‐trained joint surgeon. Cementless hemispheric porous‐coated acetabular cups and tapered cementless stems were used in all hips. The radiographic data, including leg length, the height of the center of rotation, femoral head offset, the cup anteversion and inclination angle, were measured. The cumulative sum analysis (CUSUM) and risk‐adjusted cumulative sum analysis (RA‐CUSUM) were used to determine the learning curve of DA‐THA for each patient''s operation time. By analyzing the operation time, complication rate, postoperative length of hospitalization and creatine kinase (before surgery and the third day after surgery), estimated blood loss, Harris score, radiographic data were compared between the different stages of the learning curve.ResultsThe mean follow‐up time was 35.45 ± 16.82 months. The CUSUM method obtained the maximum turning point of the curve at 43 cases, which divided the learning curve into Learning Period and Mastery Period. The CUSUM learning curve was best modeled as a cubic curve with the equation: CUSUM (min) = 0.001x ³ − 0.495x² + 33.60x − 10.00, which had a higher R ² value of 0.967. The pre‐operative data, creatine kinase, estimated blood loss and postoperative Harris scores of the two stages were not statistically significant (P > 0.05). The mean operation time was 118 min in the Learning Period and 87 min in the Mastery Period. Statistically significant differences were detected in the operation time (P < 0.001), postoperative length of hospitalization(P = 0.024), and postoperative leg length discrepancy (P = 0.012) between the two stages. The overall complication rates were 27.9% in the Learning Period and 12.3% in the Mastery Period (p = 0.049). The overall outliers of radiographic data were 34 cases in the Learning Period and 31 cases in the Mastery Period (79.07% vs 54.39%, P = 0.010).ConclusionsThe DA‐THA is a valuable alternative to achieve satisfactory clinical results for mild‐to‐moderate DDH patients. Furthermore, accurate analysis of the learning curve of DA‐THA for hip dysplasia by the CUSUM method showed that the surgeons need to finish about 43 cases to master the technique.     

Is the Acetabulum Retroverted in SCFE? A Study of Acetabular Morphology in Indian Children with SCFE

BackgroundAcetabular morphology has always been an area of interest in patients with slipped capital femoral epiphysis (SCFE). Acetabular retroversion in SCFE is proposed as a pre-disposing factor and also can predispose the hip to pincer impingement. But there is controversial data in literature regarding the acetabular morphology. All available data are from the West and we present the first study on acetabular morphology in Indian children with SCFE.MethodsCT scans of 29 patients with SCFE were collected from our database and anteversion was measured as described by Dandachli et al. Lateral central edge angle (LCEA) was measured in the standard AP radiographs of the pelvis. There were 20 boys and 9 girls with a mean age of 13.5. Seven patients had right side SCFE, eighteen had left side SCFE, and four had bilateral involvement. Measurements were done in 33 affected hips and compared with 25 normal hips.ResultsThe mean AVsup and AVcen of affected hips were 6.59° and 13.51°, respectively, and that in normal hips were 8.36° and 14.04° (p > 0.05). The mean LCEA was 23.05° on the affected hips and 25.45° on the normal hips (p > 0.05). The AVsup showed retroversion in 24.24% (8/33) of the affected hips and 20% (5/25) of the normal hips. Though the mean version was less in SCFE hips, it was not statistically significant.ConclusionOur study documents that 25% of hips with SCFE had acetabular retroversion. However, this was not significantly high compared to the contralateral hips.