Acetabular Global Insufficiency in Patients with Down Syndrome and Hip-Related Symptoms: A Matched-Cohort Study.

BACKGROUND: The etiology of hip instability in Down syndrome is not completely understood. We investigated the morphology of the acetabulum and femur in patients with Down syndrome and compared measurements of the hips with those of matched controls. METHODS: Computed tomography (CT) images of the pelvis of 42 patients with Down syndrome and hip symptoms were compared with those of 42 age and sex-matched subjects without Down syndrome or history of hip disease who had undergone CT for abdominal pain. Each of the cohorts had 23 male and 19 female subjects. The mean age (and standard deviation) in each cohort was 11.3 ± 5.3 years. The lateral center-edge angle (LCEA), acetabular inclination angle (IA), acetabular depth-width ratio (ADR), acetabular version, and anterior and posterior acetabular sector angles (AASA and PASA) were compared. The neck-shaft angle and femoral version were measured in the patients with Down syndrome only. The hips of the patients with Down syndrome were further categorized as stable (n = 21) or unstable (n = 63) for secondary analysis. RESULTS: The hips in the Down syndrome group had a smaller LCEA (mean, 10.8° ± 12.6° compared with 25.6° ± 4.6°; p < 0.0001), a larger IA (mean, 17.4° ± 10.3° compared with 10.9° ± 4.8°; p < 0.0001), a lower ADR (mean, 231.9 ± 56.2 compared with 306.8 ± 31.0; p < 0.0001), a more retroverted acetabulum (mean acetabular version as measured at the level of the centers of the femoral heads [AVC], 7.8° ± 5.1° compared with 14.0° ± 4.5°; p < 0.0001), a smaller AASA (mean, 55.0° ± 9.9° compared with 59.7° ± 7.8°; p = 0.005), and a smaller PASA (mean, 67.1° ± 10.4° compared with 85.2° ± 6.8°; p < 0.0001). Within the Down syndrome cohort, the unstable hips showed greater femoral anteversion (mean, 32.7° ± 14.6° compared with 23.6° ± 10.6°; p = 0.002) and worse global acetabular insufficiency compared with the stable hips. No differences between the unstable and stable hips were found with respect to acetabular version (mean AVC, 7.8° ± 5.5° compared with 7.6° ± 3.8°; p = 0.93) and the neck-shaft angle (mean, 133.7° ± 6.7° compared with 133.2° ± 6.4°; p = 0.81). CONCLUSIONS: Patients with Down syndrome and hip-related symptoms had more retroverted and shallower acetabula with globally reduced coverage of the femoral head compared with age and sex-matched subjects. Hip instability among those with Down syndrome was associated with worse global acetabular insufficiency and increased femoral anteversion, but not with more severe acetabular retroversion. No difference in the mean femoral neck-shaft angle was observed between the stable and unstable hips in the Down syndrome cohort. LEVEL OF EVIDENCE: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Measurement of Femoral Version by MRI is as Reliable and Reproducible as CT in Children and Adolescents With Hip Disorders.

BACKGROUND: Femoral version measurement techniques based on magnetic resonance imaging (MRI) studies have been developed as an alternative to the high levels of ionizing radiation associated with computed tomography (CT)-based methods. Previous studies have not evaluated the reliability, repeatability, and accuracy of MRI-based femoral version measurements in an adolescent population. METHODS: Subjects who underwent MRI and CT studies for clinical suspicion of hip pain secondary to hip dysplasia or femoroacetabular impingement between 2011 and 2013 were identified. Rapid sequence femoral version images were obtained from MRI Hip dGEMRIC and/or postarthrogram studies. Femoral version images were also obtained from bilateral CT lower extremity, without contrast, studies. Measurements were made by 1 fellowship-trained, pediatric hip preservation attending surgeon, 2 pediatric orthopaedic surgical fellows, and 1 fellowship-trained musculoskeletal radiologist on 2 separate occasions. Linear mixed models were used to estimate the reliability and repeatability associated with CT-based and MRI-based measurements (intraclass correlation coefficients) and to estimate the agreement (CT-MRI) between the 2 techniques. RESULTS: The mean age of 36 subjects was 15.4 years (±4.1 y). Interrater reliability was 0.91 (95% CI, 0.86-0.95) for the CT technique compared with 0.90 (95% CI, 0.86-0.94) for the rapid sequence MRI technique. Intrarater reliability for the CT technique was 0.96 (95% CI, 0.91-0.98) compared with 0.95 (95% CI, 0.90-0.97) for the MRI technique. The agreement between the MRI-based and CT-based techniques (bias: 1.9 degrees, limits of agreement: -11.3 to 14.9 degrees) was similar to the agreement between consecutive MRI measurements (bias: 0.4 degrees, limits of agreement: -7.8 to 8.6 degrees) as well as consecutive CT measurements (bias: 0.5 degrees, limits of agreement: -8.8 to 9.9 degrees). CONCLUSIONS: The interrater and intrarater reliability and repeatability estimates (intraclass correlation coefficient values) associated with both techniques was excellent (>0.90). Acquirement of axial images at the pelvis and knee during MRI for investigation of adolescents with hip pain allows for reliable measurement of femoral version. LEVEL OF EVIDENCE: Level II-diagnostic study.

Return to Play Following Open Treatment of Femoroacetabular Impingement in Adolescent Athletes.

INTRODUCTION: After treatment of femoroacetabular impingement (FAI) in adolescent competitive athletes, the rate, timing, and level of return to play have not been well reported. METHODS: Adolescent athletes who underwent open FAI treatment were assessed at a minimum 1-year follow-up. Patients completed a self-reported questionnaire centered on the time and level of return to play. Pain and functional outcomes were assessed using the modified Harris Hip Score (mHHS) and the Hip Disability and Osteoarthritis Outcome Score (HOOS). RESULTS: Among the 24 athletes included, 21 (87.5%) (95% confidence interval [CI], 67.6% to 97.3%) successfully returned to play after open FAI treatment. The median time to return to play was 7 months (95% CI, 6 to 10 months). Of the 21 who returned to play, 19 (90%) returned at a level that was equivalent to or greater than their level of play before surgery. Three athletes (12.5%) did not return to play and indicated that failure to return to play was unrelated to their hip. There was significant improvement in the mHHS (P < 0.0001), HOOS (P < 0.0001), α angle (P < 0.0001), and offset (P < 0.0001). DISCUSSION: Most adolescent athletes can expect to return to the same or better level of sports participation during the first year after open treatment of FAI.

Surgical Hip Dislocation for the Treatment of Intra-Articular Injuries and Hip Instability Following Traumatic Posterior Dislocation in Children and Adolescents.

BACKGROUND: Traumatic posterior hip dislocation in children is a rare injury that typically is treated with closed reduction. Surgical treatment is typically recommended for nonconcentric reduction with joint space asymmetry with entrapped labrum or an osteochondral fragment. The surgical hip dislocation (SHD) approach allows for full assessment of the acetabulum and femoral head and has been our preferred surgical strategy. The purpose of this study was to (1) describe the intra-articular pathologic findings seen at the time of SHD; and (2) to investigate hip pain, function, and activity level of a cohort of children and adolescents after open treatment of a posterior hip dislocation using the SHD approach. METHODS: Following IRB approval, 23 patients who sustained a traumatic posterior hip dislocation between January 2009 and December 2013 were identified. In 8/23 (34.8%) patients there was evidence of nonconcentric reduction after closed treatment and surgical treatment was performed using the SHD approach. Seven male and 1 female (mean age, 11.2 y; range, 6 to 14.6 y) were followed for an average of 28 months (range, 13 to 67 mo). The modified Harris Hip Score (mHHS) and the University of California Los Angeles activity score assessed clinical hip outcome and activity level at minimum of 1 year after surgery. RESULTS: Six patients were treated after an acute trauma, whereas 2 were treated after recurrent dislocations. Five patients were involved in motor vehicle accidents and 3 in sports-related injuries. Intraoperative findings include posterior labral avulsion in all patients, fracture of the cartilaginous posterior wall (n=3), and femoral head chondral injuries (n=5) and fracture (n=1). The labral root was repaired using suture anchor technique in 7/8 patients and resected in 1. In 2 patients, labral repair was complemented by screw fixation of the posterior wall. All but one patient (mHHS=94) reported maximum mHHS. The University of California Los Angeles activity score was 10 for 5/8 patients and 7 in 3 patients. No case of femoral head osteonecrosis was noted. One patient developed an asymptomatic heterotopic ossification. CONCLUSIONS: When open reduction is recommended for the treatment of intra-articular pathologies and hip instability following traumatic dislocation of the hip in children and adolescents, the SHD is an excellent approach that allows surgical correction of the damaged bony and soft-tissue structures including repair of the capsule-labral complex, and reduction and internal fixation of the cartilaginous posterior wall and femoral head fractures. LEVEL OF EVIDENCE: Level IV.

Acetabular Remodeling After a Varus Derotational Osteotomy in Children With Cerebral Palsy.

BACKGROUND: The optimal surgical intervention for hip dysplasia in cerebral palsy (CP) is controversial. The purpose of this study was to determine (1) whether an isolated varus derotation osteotomy (VDRO) for the treatment of CP hip dysplasia allows for acetabular remodeling as measured by acetabular depth ratio (ADR), (2) the predictive factors for acetabular remodeling after an isolated VDRO for the treatment of CP hip dysplasia, and (3) to establish the normal ADR in typical children for comparison. METHODS: Eighty-seven CP patients (174 hips) treated with an isolated VDRO between 2003 and 2009 were retrospectively reviewed. The average age at surgery was 4.6 years (range, 2.4 to 10.6 y) and the average follow-up period was 5.1 years (range, 1.1 to 9.9 y). Acetabular remodeling was assessed on radiographs by the ADR. Changes in preoperative and postoperative ADR were analyzed using linear mixed-effects models. Patients were divided into 2 different groups for the postoperative ADR analysis: Gross Motor Function Classification System (GMFCS) levels I, II, and III compared with GMFCS levels IV and V. The progression of ADR versus age was determined in a set of 917 normal children (1834 hips) for comparison. RESULTS: There was a statistically significant increase (improvement) in ADR postsurgically for the collective CP set (P<0.001) and for both GMFCS categories (I/II/III, IV/V: P<0.001). GMFCS level, sex, and intraoperative neck shaft angle (NSA) were determined to be significant predictors for postoperative ADR improvement. GMFCS level was the most significant predictor for an increase in ADR after surgery (P<0.001). Less improvement in ADR was observed in patients of GMFCS levels IV and V compared with patients of GMFCS levels I, II, and III (P<0.001). A lower intraoperative NSA resulted in greater postoperative increase in ADR (P<0.05). CONCLUSIONS: Overall, isolated VDRO allowed for acetabular remodeling in CP hip dysplasia. Acetabular remodeling was increased in patients of GMFCS levels I, II, and III compared with patients of GMFCS levels IV and V. Increased varization at the time of VDRO improved acetabular remodeling. This study recommends considering GMFCS level and intraoperative NSA during surgical planning for CP hip dysplasia.

Rate of Correction and Recurrence of Ankle Valgus in Children Using a Transphyseal Medial Malleolar Screw.

BACKGROUND: Transphyseal medial malleolar screw (TMMS) hemiepiphysiodesis is an effective treatment for ankle valgus in children. There is limited evidence on the effect of age and diagnosis on the rate of correction as well as the deformity recurrence after screw removal. The purpose of this study was to determine (1) the rate of correction of ankle valgus after hemiepiphysiodesis using a TMMS, (2) the effects of clinical diagnosis and age at surgery on the rate of correction, and (3) the rate of valgus recurrence after TMMS removal. METHODS: In this retrospective study we included 16 male and 21 female patients (63 ankles) with an average age at surgery of 11.0 years (range, 5.4 to 14.8 y) who underwent TMMS hemiepiphysiodesis for the treatment of ankle valgus. There was a mean radiographic follow-up of 1.6 years (range, 0.4 to 4.9 y) before screw removal. For subjects who received screw removal (43 ankles), the average time from insertion to removal of the screw was 1.4 years (range, 0.4 to 5.2 y). Valgus deformity was assessed on anteroposterior ankle radiographs by measurement of tibiotalar angle. Linear mixed effects models were used to determine rates of correction and valgus recurrence. RESULTS: The average rate of correction in tibiotalar angle was 0.37±0.04 degrees per month (P<0.001). Clinical diagnosis and age at surgery significantly affected the amount of postoperative correction in tibiotalar angle (P<0.05). Eighteen of 22 ankles (81.8%) demonstrated recurrence of ankle valgus after screw removal. The average recurrence rate in patients who underwent screw removal was 0.28±0.08 degrees per month (22 ankles, P=0.002). CONCLUSIONS: This study supports the effectiveness of the TMMS hemiepiphysiodesis for treating pediatric ankle valgus, but the effects of additional skeletal growth should be considered as the ankle may rebound into valgus after correction and screw removal. The results from this study can help with surgical planning to predict the amount of correction that may be achieved depending on underlying diagnosis and age at surgery. LEVEL OF EVIDENCE: Level IV-retrospective study.