Measuring the Acetabular Index: An Accurate and Reliable Alternative Method of Measurement.

OBJECTIVE. In children (4 months to 8 years old), radiographic measurements of the acetabular index are the preferred method to assess developmental hip dysplasia. However, the acetabular index has been criticized as having variable reliability owing to difficulty identifying the correct anatomic landmarks. An alternative method of measuring the acetabular index using the ischium is being proposed to avoid the variability of the triradiate cartilage line as a reference point. With the alternative method, the acetabular index is derived by measuring the angle between a line connecting the ischial tuberosi-ties and a line connecting the inferomedial and superolateral edges of the acetabulum. The purpose of this study was to evaluate the accuracy and reliability of this alternative method of measuring the acetabular index compared with the traditional method. MATERIALS AND METHODS. Children 4 months to 8 years old who presented for evaluation of developmental dysplasia of the hip were included. Two physicians, each using both the traditional and the alternative method, measured acetabular indexes on all radiographs. Accuracy was defined as mean absolute error less than 6°. Reliability was calculated by means of intraclass correlation coefficient (ICC). RESULTS. Pelvic radiographs of 40 children (324 hips) were included. The mean age was 23.7 months (range, 4-96 months) and mean acetabular index was 24.2° (range, 8-50°). The alternative method was associated with mean absolute error of 2.50°, which is significantly below the threshold of 6° (t < 0.001). Intrarater reliability for the traditional method was high (ICC, 0.81) and for the alternative method was very high (ICC, 0.92). Interrater reliability for the traditional method was high (ICC, 0.89) and for the alternative method was very high (ICC, 0.91). CONCLUSION. Measuring the acetabular index using the alternative method has very high accuracy and intrarater and interrater reliability.

Advanced containment methods for Legg-Calvé-Perthes disease: results of triple pelvic osteotomy.

BACKGROUND: Although surgical containment has become a mainstay for the treatment of Legg-Calvé-Perthes (LCP) disease; traditional operations (varus osteotomy of femur, Salter osteotomy) have certain limitations, sometimes resulting in a prolonged limp or inadequate containment. This paper presents the surgical method and results of triple pelvic osteotomy for containment treatment of LCP disease. METHODS: This retrospective review of 39 children (40 hips; age 5 to 13 y) with LCP disease treated with triple pelvic osteotomy (1995 to 2005) included preoperative lateral pillar assessment and other measurements. Final follow-up films (minimum 3 y, range 3 to 9 y) were assessed using the modified Stulberg classification. Clinical follow-up evaluation assessed limp, limb-length inequality, range of motion, and activity level. RESULTS: Twenty-one (53%) hips were graded as lateral pillar B and 19 (48%) were lateral pillar C. Four patients required further treatment before the final follow-up. At final follow-up, 42% had a good outcome (Stulberg I/II), 47% had a fair outcome (Stulberg III), and 11% had a poor outcome. Thus, 89% of patients had satisfactory (good or fair) results. There was a significant difference in outcome based on the preoperative lateral pillar, with B hips more likely to have a good outcome (65%) compared with lateral pillar C hips (12.5%) (P=0.002). There were no lateral pillar B patients with a poor outcome. Seventeen percent of the lateral pillar C patients more than or equal to age 8 had a poor outcome compared with 50% being more than age 8 with a poor outcome. Four patients (3 lateral pillar C, 1 lateral pillar B) required further surgery. CONCLUSIONS: Triple pelvic osteotomy resulted in maintenance of head shape in lateral pillar B patients of all ages and in younger lateral pillar C patients. Lateral pillar C patients over age 8 were more difficult to treat, however, we still advise containment for these cases because methods are now available to deal with containment failure. Triple pelvic osteotomy is an effective treatment method for LCP patients with lateral pillar B disease and younger patients with lateral pillar C disease. This method provides effective containment, which allows prolonged remodeling while avoiding the limitations of femoral varus osteotomy (limp, short limb) and Salter osteotomy (incomplete containment). LEVEL OF EVIDENCE: Level IV.

The healing forearm fracture: a matched comparison of forearm refractures.

BACKGROUND: Forearm fractures in children usually heal rapidly after closed treatment. Recent studies report forearm refracture rates of 5%. The purpose of this study was to identify risk factors for refracture based on radiographic variables. METHODS: We performed a retrospective review of patients that sustained a second forearm fracture (refracture) between 1998 and 2005. Refractures were defined as having a second fracture of the same forearm within 18 months of the original fracture. A comparison group of single-fracture patients followed in a capitated insurance plan were included and matched based on age and sex. Radiographic assessment included initial/final angulation, displacement, and fracture-line visibility at latest follow-up. RESULTS: Sixty-three refractures were compared with 132 age- and sex-matched single-fracture patients. Time to refracture averaged 10 months. Thirty-eight percent of the initial fractures in the refracture group occurred in the proximal or middle third of the forearm compared with 15% for the single-fracture patients (P < 0.001). Because location of the fracture was found to be a risk factor for refracture, a secondary analysis was performed with refracture patients matched to single-fracture patients based on age, sex, bone fractured, fracture location, and treatment method. Fracture-line visibility of the radius at latest follow-up was clearly visible in 48% of refractures compared with 21% of controls (P = 0.05). Initial fracture severity and residual deformity were not significantly different. CONCLUSIONS: Proximal and middle one third forearm fractures are at greater risk of refracture compared with distal one third forearm fractures. There was a trend toward incomplete healing seen more commonly in those that refractured, emphasizing the importance of longer immobilization in these fractures. LEVEL OF EVIDENCE: Prognostic study, level III, case-control study.

Biomechanical stability of bioabsorbable screws for fixation of acetabular osteotomies.

The purpose of this study was to compare the biomechanical stability of triple innominate osteotomies fixed with either bioabsorbable or stainless steel screws. Triple innominate osteotomies were performed on composite hemipelves and fixed with either three 4.5-mm bioabsorbable screws or three stainless steel 4.5-mm screws. Two screws were placed from the iliac wing into the acetabular fragment, and 1 screw was placed from below the acetabular fragment into the iliac wing. Eight specimens for each screw type were biomechanically tested in an anatomical position (replicating weight bearing) and in a flexed and abducted position (replicating spica cast positioning). Specimens were cyclically loaded between 10 and 450 N to simulate the hip contact force in this population. Lower screws were then removed, and specimens were tested under identical conditions. Fragment displacement (mm) and construct stiffness (N/mm) were compared with a 2-way analysis of variance (P < 0.05). There were no significant differences between materials for fragment displacement or construct stiffness. Anatomical position showed significantly less displacement than spica position for both materials. Initial displacement in the spica position was significantly less during lower loads for stainless steel fixation. Bioabsorbable screws demonstrate comparable biomechanical stability to stainless steel screws in anatomical and spica positions at physiological loads. Flexion and abduction of the femur adversely affect the stability of the construct for both materials. Bioabsorbable screws behave similarly to steel screws when stabilizing triple innominate osteotomies and would have the advantage of not requiring a second surgery for screw removal. Confirmation of biocompatibility should be completed before widespread clinical application.

Intramedullary flexible nail fixation of unstable pediatric tibial diaphyseal fractures.

Flexible intramedullary nail fixation provides excellent fixation in children with unstable tibial shaft fractures, but few published series demonstrate the results and complications with this technique in children. A retrospective review of 19 patients was performed, as well as a biomechanical analysis of two implant configurations. Outcome measures included union rates, residual deformity, and complications. Union occurred in all cases. Five patients (26%) had complications. None required repeat operation. Two (11%) angular deformities (>/=10 degrees) occurred with the medial C and S construct, versus none with the double C. The C and S construct was more stable to mechanical testing with axial and torsional loading. Flexible intramedullary nail fixation is a straightforward technique that reliably produces good results. While the C and S construct was superior in biomechanical testing, the double C construct is more reliable and straightforward and remains by far the authors' preferred technique.

Biomechanical comparison of stainless steel and titanium nails for fixation of simulated femoral fractures.

Flexible intramedullary nails are commonly used to treat femoral fractures in children. This study evaluated the biomechanical differences between stainless steel and titanium nails when securing transverse and comminuted fractures in a synthetic femur model. Retrograde flexible stainless steel and titanium nails placed in a divergent "C" pattern were mechanically tested, and axial rotation and compression stiffness were analyzed with a two-way ANOVA. Rotational stability was significantly greater for titanium nails than stainless steel nails for both fracture patterns. Axial compression stiffness was significantly greater for titanium nails than stainless steel nails for both fracture patterns. There was no statistical difference between materials for axial "failure" load that produced 5 mm of shortening. Titanium intramedullary nails were more stable than stainless steel nails in torsion and axial compression. Both materials stabilized simulated fractures at levels beyond physiologic non-weight-bearing loads without permanent deformation.

Surgical correction of residual hip dysplasia in two pediatric age-groups.

BACKGROUND: The goal of operative treatment of hip dysplasia or subluxation in children is to normalize the hip joint to delay or prevent the premature onset of osteoarthritis. In theory, intervention in early childhood, when the remodeling potential is greater, should provide the best opportunity for the development of a normal joint. METHODS: To determine the efficacy of early surgical intervention in restoring the normal morphology of the hip, according to radiographic criteria, we reviewed the cases of thirty-six children (fifty hips) with residual dysplasia or subluxation who were managed with either a femoral and/or a pelvic osteotomy when they were between two and eight years old (Group I). The average age at the time of surgery was 3.7 years, and the average duration of follow-up was 4.3 years. We compared these results with those achieved in fourteen patients (eighteen hips) with residual hip dysplasia or subluxation who were treated surgically at an older age, between eight and eighteen years old (Group II). The outcome was assessed with use of clinical as well as multiple radiographic criteria. We believe that a normal relationship between the acetabulum and the femoral head was established when there was an acetabular index of <20 degrees or a Sharp angle of <42 degrees, a center-edge angle of >20 degrees, and an intact Shenton's line. RESULTS: At the time of the latest follow-up, sixteen of the seventeen hips with residual dysplasia that had been treated with pelvic osteotomy alone in Group I and three of four such hips in Group II had a normal relationship between the acetabulum and the femoral head. Normal radiographic findings were noted in fifteen of the seventeen hips with residual subluxation that had been treated with combined femoral and pelvic osteotomies in Group I compared with four of eight such hips in Group II. CONCLUSIONS: We found that residual hip dysplasia or subluxation could be more predictably corrected, with normal radiographic results and with less morbidity and fewer complications, in children who were between two and eight years old than in those who were between eight and eighteen years old. Long-term follow-up is required to confirm whether the improved anatomy and function of the hip that resulted from early correction of residual dysplasia or subluxation lasts into adulthood.