Hip damage occurs at the zone of femoroacetabular impingement.

UNLABELLED: Although current concepts of anterior femoroacetabular impingement predict damage in the labrum and the cartilage, the actual joint damage has not been verified by computer simulation. We retrospectively compared the intraoperative locations of labral and cartilage damage of 40 hips during surgical dislocation for cam or pincer type femoroacetabular impingement (Group I) with the locations of femoroacetabular impingement in 15 additional hips using computer simulation (Group II). We found no difference between the mean locations of the chondrolabral damage of Group I and the computed impingement zone of Group II. The standard deviation was larger for measures of articular damage from Group I in comparison to the computed values of Group II. The most severe hip damage occurred at the zone of highest probability of femoroacetabular impact, typically in the anterosuperior quadrant of the acetabulum for both cam and pincer type femoroacetabular impingements. However, the extent of joint damage along the acetabular rim was larger intraoperatively than that observed on the images of the 3-D joint simulations. We concluded femoroacetabular impingement mechanism contributes to early osteoarthritis including labral lesions. LEVEL OF EVIDENCE: Level II, diagnostic study. See the Guidelines for Authors for a complete description of levels of evidence.

Application of surgical navigation to total hip arthroplasty.

Instability, impingement, and leg-length discrepancy are among the most common early problems following total hip arthroplasty (THA). Component positioning is the primary factor affecting all three of these issues and, therefore, all three can be potentially addressed using surgical navigation. While the advent of less invasive surgical techniques performed through smaller incisions has been shown to accelerate recovery, these techniques have also been associated with a further increase in the incidence of these three problems. Acetabular component malpositioning has been a particular problem with less invasive surgical techniques. Nonetheless, it is clear that maximal preservation of the soft tissues around the hip joint may accelerate recovery following surgery and confer greater hip joint stability. Accomplishing these goals without compromising component positioning is the single greatest potential advantage to the application of surgical navigation to THA. The present paper describes the general principles of surgical navigation in THA with respect to methods of tracking, methods of registration, the role of image-free and image-based navigation, and methods of measuring leg-length change during surgery. Further, a description is given of the clinical effect of combining surgical navigation with use of the superior capsulotomy technique of performing THA, which aims maximally to preserve the soft tissues surrounding the hip joint, allowing unrestricted progression of motion and weight-bearing following surgery. These methods have led to statistically significant acceleration of recovery, improvement in acetabular component positioning, and reductions in peri-operative surgical complications.

Range of motion in anterior femoroacetabular impingement.

The range of motion of normal hips and hips with femoroacetabular impingement relative to some specific anatomic reference landmarks is unknown. We therefore described: (1) the range of motion pattern relative to landmarks; (2) the location of the impingement zones in normal and impinging hips; and (3) the influence of surgical débridement on the range of motion. We used a previously developed and validated noninvasive 3-D CT-based method for kinematic hip analysis to compare the range of motion pattern, the location of impingement, and the effect of virtual surgical reconstruction in 28 hips with anterior femoroacetabular impingement and a control group of 33 normal hips. Hips with femoroacetabular impingement had decreased flexion, internal rotation, and abduction. Internal rotation decreased with increasing flexion and adduction. The calculated impingement zones were localized in the anterosuperior quadrant of the acetabulum and were similar in the two groups and in impingement subgroups. The average improvement of internal rotation was 5.4 degrees for pincer hips, 8.5 degrees for cam hips, and 15.7 degrees for mixed impingement. This method helps the surgeon quantify the severity of impingement and choose the appropriate treatment option; it provides a basis for future image-guided surgical reconstruction in femoroacetabular impingement with less invasive techniques.

[Conventional vs minimally invasive total hip arthroplasty. A prospective study of rehabilitation and complications]. / Herkömmliche vs. minimal-invasive Hüftendoprothetik : Eine prospektive Studie über Rehabilitation und Komplikationen.

BACKGROUND: In a prospective, nonrandomized study the outcome in terms of rehabilitation and complications of total hip arthroplasty (THA) through a superior capsulotomy exposure (study group) was compared to THA performed through a direct lateral exposure (control group). PATIENTS AND METHODS: The study group (106 THA) and the control group (107 THA) were controlled for complexity and had no significant differences in age, sex, diagnosis, or body mass index. RESULTS: The study group had improved recovery at 6 weeks after surgery which was statistically significant (p<0.001). In addition, the study group had a lower incidence of perioperative complications. CONCLUSION: The current study demonstrates the potential that less-invasive surgical techniques with the philosophy of maximally preserving the abductors, posterior capsule, and short rotators may result in a safer operation with an accelerated recovery.

Estimation of pelvic tilt on anteroposterior X-rays--a comparison of six parameters.

OBJECTIVE: To compare six different parameters described in literature for estimation of pelvic tilt on an anteroposterior pelvic radiograph and to create a simple nomogram for tilt correction of prosthetic cup version in total hip arthroplasty. DESIGN: Simultaneous anteroposterior and lateral pelvic radiographs are taken routinely in our institution and were analyzed prospectively. The different parameters (including three distances and three ratios) were measured and compared to the actual pelvic tilt on the lateral radiograph using simple linear regression analysis. PATIENTS: One hundred and four consecutive patients (41 men, 63 women with a mean age of 31.7 years, SD 9.2 years, range 15.7-59.1 years) were studied. RESULTS: The strongest correlation between pelvic tilt and one of the six parameters for both men and women was the distance between the upper border of the symphysis and the sacrococcygeal joint. The correlation coefficient was 0.68 for men (P<0.001) and 0.61 for women (P<0.001). Based on this linear correlation, a nomogram was created that enables fast, tilt-corrected cup version measurements in clinical routine use. CONCLUSION: This simple method for correcting variations in pelvic tilt on plain radiographs can potentially improve the radiologist's ability to diagnose and interpret malformations of the acetabulum (particularly acetabular retroversion and excessive acetabular overcoverage) and post-operative orientation of the prosthetic acetabulum.

Results of a randomized phase III trial in children and adolescents with advanced stage diffuse large cell non Hodgkin's lymphoma: a Pediatric Oncology Group study.

The Pediatric Oncology Group (POG) adopted a histology-based approach to the management of pediatric non-Hodgkin's lymphomas (NHL) utilizing the National Cancer Institute Working Formulation for Clinical Usage. Patients with diffuse large cell lymphoma (DLCL) were treated on a separate protocol from small cell diffuse undifferentiated or lymphoblastic lymphomas. This study assessed the overall and event free survival of children with DLCL and determined the effects of cyclophosphamide upon these end-points in a prospective randomized trial. One hundred and twenty eligible stage III or IV NHL patients with the confirmed diagnosis of diffuse large cell or immunoblastic histology were enrolled on study between October 1986 and November 1991. Patients were randomized to receive or not receive cyclophosphamide; 58 received cyclophosphamide, doxorubicin, vincristine, 6-mercaptopurine (6-MP), and prednisone (ACOP+) and 62 were treated with doxorubicin, vincristine, 6-MP, and prednisone (APO). In both treatment programs methotrexate was substituted when the doxorubicin cumulative dose reached 450 mg/m2. Radiation was administered to bulky disease if progression or no response were observed after induction therapy. Planned duration of therapy was 12 months. The 5-year event free survival (EFS) rates of patients treated with ACOP+ versus APO were 62% +/- 7% and 72% +/- 6%, respectively. While there was no statistically significant difference between the two treatment arms (p = 0.28), we can only say that we are 95% confident that the difference in 5-year EFS falls in the wide range from 28% in favor of APO to 8% favoring ACOP+. Marrow suppression was the main toxicity with one fatal infection. There were three other deaths on study due to respiratory failure in patients with mediastinal masses. Only one patient experienced cardiotoxicity requiring discontinuation of doxorubicin. Ten patients received radiation therapy to achieve. In conclusion the efficacy of elimination of cyclophosphamide from the treatment program of children and adolescents with advanced stage diffuse large cell lymphoma was inconclusive as to its effect on EFS. Furthermore, the majority of the patients (92%) did not require any radiation therapy to bulky disease indicating that the chemotherapy regimens are quite efficient for achievement of complete remission.

Childhood cancer: patterns of protocol participation in a national survey.

Cancer is still the chief cause of death by disease in children, ages one to 14. As improved survival rates have been reported for pediatric cancer patients who are treated on controlled clinical trials, it is important to understand the national utilization of such protocols. In 1993, a survey of childhood cancer was conducted by the Commission on Cancer of the American College of Surgeons. Data regarding type of disease, protocol participation, age, sex, race, insurance, and geographical region were voluntarily submitted by more than 200 hospital cancer registries. Included in this study were 2,208 children and adolescents 21 years of age or younger who were diagnosed in 1987, and 2,293 who were diagnosed in 1992. Pediatric centers (i.e., members of the Pediatric Oncology Group or Children's Cancer Group) submitted 55.1% of the cases and other institutions, 44.9%. It was found that more patients treated at pediatric centers were on protocols (53.8%) than were those treated at other institutions (25.1%). In general, the younger the patient (five years of age or younger), the greater the chance of being on protocol (pediatric centers, 63.7%; others, 42.0%), with very poor adolescent protocol participation (pediatric centers, 34.8%; others, 12.1%). Nevertheless, overall protocol participation was still lower than expected, even in children younger than five years of age, and adolescent participation in controlled clinical trials was low and similar to adult figures. The percentage of childhood cancer cases seen at pediatric centers was smaller than in other series. It was concluded that pediatric cancer centers need to continue to encourage patient participation in controlled clinical trials, with special emphasis on adolescents.

Shear creep of gelatin gels from mammalian and piscine collagens.

This paper describes new measurements on the creep rheological behaviour of gelatin gels from both traditional mammalian and piscine sources. Measurements on a series of concentrations of gels were obtained using a high-precision controlled stress rheometer. Results for the concentration dependence of compliance are close to those expected from dynamic oscillatory measurements of gel modulus, assuming ideal elasticity. The concentration dependence of viscosity approximates power law behaviour, with eta~C( approximately 2-3), lower than the exponent expected for semi-dilute solutions. The apparent contradiction implied by this is discussed and a novel gel viscosity versus concentration state diagram presented.

Natural killer cell lymphoma: report of two pediatric cases, therapeutic options, and review of the literature.

BACKGROUND: Natural killer (NK) cell lymphomas are rapidly fatal malignancies that to the authors' knowledge are rare in children. In the current study, the authors report the cases of two boys with NK cell lymphomas with refractory disease who both were salvaged with high dose chemotherapy and stem cell transplantation and compare these patients with those in the published experience. METHODS: A comprehensive literature review was performed to identify other cases of pediatric patients with NK cell lymphomas, their treatment, and outcome. RESULTS: One of the patients in the current study developed two recurrences and the other patient experienced early disease progression during front-line treatment. Both then were treated with high dose chemotherapy followed by stem cell rescue. At last follow-up, the patients remained free of disease at 15 months and 16 months, respectively, after transplantation (48 months and 22 months, respectively, from the time of diagnosis). In addition to the 2 patients in the current study, the authors found 13 pediatric patients reported in the literature to date. Of the 7 patients with localized (Stage I-II) disease, 5 patients (71%) were reported to be alive 1-107 months after diagnosis. Of the 6 patients with Stage IV disease, only the 2 patients who received high dose chemotherapy and stem cell rescue (33%) were alive at the time of last follow-up (at 30 months and 12 months, respectively). Including the patients reported in the current study, 9 of 15 children with NK cell lymphoma (all stages) (60%) were reported to be alive at the time of last follow-up. CONCLUSIONS: Although pediatric NK cell lymphomas rapidly can become fatal, it appears that high dose chemotherapy followed by stem cell transplantation is effective therapy, especially in patients with advanced or resistant disease. Further follow-up is needed to determine whether this treatment approach will be curative.

Pressure cell assisted solution characterization of polysaccharides. 1. Guar gum.

To reduce time-dependent aggregation phenomena and achieve true "molecular" solution, the "pressure cell" solubilization method of Vorwerg and co-workers was applied to solutions of guar galactomannans (three samples of different molecular weights), using various heating, time, and pressure profiles. Physicochemical characterization of the guar samples before and after pressure cell treatment included measurements of intrinsic viscosity [eta] by capillary viscometry and M(w) and radius of gyration from size exclusion chromatography coupled to multiangle laser light scattering (SEC/MALLS). Heating the guar solutions (100-160 degrees C) without pressurization produced chain degradation with [eta] and M(w) values being reduced significantly, whereas this effect was reduced substantially for samples subject to initial pressurization ( approximately 5-10 bar). The constants in the Mark-Houwink-Sakurada equation, relating [eta] and M(w) were established and the characteristic ratio C(infinity) and chain persistence length L(p) were calculated using both the Burchard-Stockmayer-Fixman (BSF) method for flexible and semiflexible chains and the Hearst method more appropriate for stiffened chains. Definitive conclusions can now be drawn on the flexibility of the guar chain backbone, with L(p) approximately 4 nm from the BSF plot, in good agreement with previously published work using such geometric methods. This contrasts with the higher values obtained from extrapolation of data for polyelectrolytes with a similar backbone geometry, such as sodium carboxymethyl cellulose, to "infinite" ionic strength.

Heat-induced gelation of globular proteins: part 3. Molecular studies on low pH beta-lactoglobulin gels.

Heat-set gels and aggregates from beta-lactoglobulin (beta-Lg), one of the major globular proteins from milk, have been studied on a molecular distance scale using negative-staining transmission electron microscopy (TEM), wide-angle X-ray diffraction (WAXD), and Fourier transform infrared spectroscopy (FTIR). The microscopy showed long linear aggregates forming in solutions at pH 2 (and sometimes 2.5) after prolonged heating. While there appeared to be no differences in aggregates formed under these conditions in H(2)O as compared with D(2)O, at all other pH and pD values, and in the presence of added salt, much shorter linear aggregates were formed. These became slightly more extended the further the pH was removed from pI. Wide-angle X-ray diffraction (WAXD) showed a diffuse beta-sheet halo at 2θ=19 degrees in patterns for both dried native and aggregated protein (irrespective of pH) with only a small change (sharpening) of this feature on heat treatment. Solution FTIR spectra, measured at pD=2, 2.5, 3, and 7, during heating, indicated shoulder development at 1612 cm(-1) in the carbonyl-stretching Amide I region diagnostic of a modest increase in intermolecular beta-sheet. In terms of the shoulder size, no distinctions could be made between acid and neutral aggregate structures. At all pHs, beta-lactoglobulin showed only limited secondary and tertiary structural changes in aggregation, in contrast to previous studies of insulin aggregation, where highly ordered crystalline fibrils were indicated. The current work has implications both in structural studies of food biopolymers and in ongoing studies of pathological protein self-assembly in disease states, such as spongiform encephalopathies.

CNS involvement in children with newly diagnosed non-Hodgkin's lymphoma.

PURPOSE: To determine the frequency of CNS involvement at diagnosis of non-Hodgkin's lymphoma (NHL), to characterize its pattern of presentation, and to determine its prognostic significance. PATIENTS AND METHODS: We reviewed the records of 445 children (1975 through 1995) diagnosed with NHL (small noncleaved cell NHL/B-cell acute lymphoblastic leukemia [SNCC NHL/B-ALL], 201 patients; lymphoblastic, 113; large cell, 119; other, 12). Tumor burden was estimated by serum lactate dehydrogenase (LDH) measurement and reclassification of disease stage irrespective of CNS involvement (modified stage). RESULTS: Thirty-six of 445 children with newly diagnosed NHL had CNS involvement (lymphoma cells in the CSF [n = 23], cranial nerve palsy [n = 9], both features [n = 4]), representing 13%, 7%, and 1% of small noncleaved cell lymphoma, lymphoblastic lymphoma, and large-cell cases, respectively. By univariate analysis, CNS disease at diagnosis did not significantly impact event-free survival (P =. 095), whereas stage and LDH did; however, children with CNS disease at diagnosis were at 2.0 times greater risk of death than those without CNS disease at diagnosis. In a multivariate analysis, CNS disease was not significantly associated with either overall or event-free survival, whereas both serum LDH and stage influenced both overall and event-free survival. Among cases of SNCC NHL/B-ALL, CNS disease was significantly associated with event-free and overall survival (univariate analysis); however, in multivariate analysis, only LDH had independent prognostic significance. Elevated serum LDH or higher modified stage were associated with a trend toward poorer overall survival among children with CNS disease. CONCLUSION: A greater tumor burden at diagnosis adversely influences the treatment outcome of children with NHL and CNS disease at diagnosis, suggesting a need for ongoing improvement in both systemic and CNS-directed therapy.

Slow disappearance of peripheral blood blasts is an adverse prognostic factor in childhood T cell acute lymphoblastic leukemia: a Pediatric Oncology Group study.

The rapidity of response to induction therapy is emerging as an important prognostic factor in children and adolescents with acute lymphoblastic leukemia (ALL). We studied the relationship between rapidity of reduction in peripheral blood blast count and treatment outcome in children with T cell ALL (T-ALL). Initial systemic chemotherapy included prednisone, vincristine, doxorubicin and cyclophosphamide. A Cox analysis evaluated the correlation between the length of time that the peripheral blood absolute blast count (ABC) remained above 1000/mm3 following the start of treatment and event-free survival (EFS). Data were available for 281 patients. Patients for whom the ABC remained >1000/mm3 for 3 or more days following administration of intensive therapy had an estimated 5-year EFS of 34.2% (s.e. = 7.2) vs 58.3% (3.5) for those whose ABC was <1000/mm3 within 0-2 days, with a hazard ratio (HR) of failure of 2.03 (95% CI = 1.35-3.06, P < 0.001) for the slower responding patients. Pre-treatment of some type (usually with prednisone) occurred in 128 patients (average duration 1.7 days). When this was accounted for, patients with an ABC >1000/mm3 for 5 or more days following the start of treatment of any kind had a HR for failure of 2.27 (95% CI = 1.38-3.72, P < 0.001) compared to those responding within 0-4 days. Inclusion of other clinical and biological factors in a multivariate analysis did not alter the prognostic importance of slower blast clearance. Pediatric patients with T-ALL who have a circulating blast count >1000/mm3 at diagnosis and a relatively slower response to initial treatment are at increased risk of treatment failure. Rapidity of response may therefore be a clinically useful prognostic factor for patients with T-ALL.

Molecular and virologic characteristics of lymphoid malignancies in children with AIDS.

PURPOSE: To characterize AIDS-associated lymphoid malignancies in children. PATIENTS AND METHODS: We studied lymphomas and B-cell leukemias from 25 children with AIDS for immunoglobulin heavy chain gene clonality, c-myc oncogene abnormalities, and presence of HIV and Epstein-Barr virus. RESULTS: Monoclonal immunoglobulin gene rearrangements were identified in 22 of 23 cases tested, the single exception being one of mucosa-associated lymphoid tissue. Immunoglobulin gene/c-myc translocations were found in 3 of 4 cases of B (surface immunoglobulin-positive)-acute lymphoblastic leukemia, 8 of 11 small noncleaved cell lymphomas, and 1 of 5 large cell lymphomas. Mutations of c-myc were found in 2 of 13 small noncleaved cell lymphomas, 1 of 2 Epstein-Barr virus-positive mucosa-associated lymphoid tissue neoplasms, and 1 of 4 Epstein-Barr virus-negative B-acute lymphoblastic leukemia. Six small noncleaved cell lymphomas, both mucosa-associated lymphoid tissue neoplasms and one of large cell lymphoma had high levels of Epstein-Barr virus in tumor tissue. Hodgkin's disease tissue and B-acute lymphoblastic leukemia tumors were negative for EBV. Proviral HIV-1 was not detected in any tumor. CONCLUSIONS: AIDS-associated lymphoid malignancies in children appear to have a different distribution of histologic subtypes than adult HIV-infected individuals, fewer large cell lymphomas occur in children. The small noncleaved cell lymphomas exhibit a lower frequency as well as different locations of c-myc mutations than AIDS-associated small noncleaved cell lymphomas in adults.

Effects of cranial radiation in children with high risk T cell acute lymphoblastic leukemia: a Pediatric Oncology Group report.

Contemporary chemotherapy has significantly improved event-free survival among patients with T cell-lineage acute lymphoblastic leukemia (T-ALL). Unlike B-precursor ALL, most investigators are still using cranial radiation (CRT) and are hesitant to rely solely on intrathecal therapy for T-ALL. In this study we assessed the effects of CRT upon event-free survival and central nervous system (CNS) relapses in a cohort of children with high risk features of T cell leukemia. In a series of six consecutive studies (1987-1995) patients were non-randomly assigned their CNS prophylaxis per individual protocol. These protocols were based on POG 8704 which relied on rotating drug combinations (cytarabine/cyclophosphamide, teniposide/Ara-C, and vincristine/doxorubicin/6-MP/prednisone) postinduction. Modifications such as high-dose cytarabine, intermediate-dose methotrexate, and the addition of G-CSF, were designed to give higher CNS drug levels (decreasing the need for CRT), to eliminate epidophyllotoxin (decreasing the risk of secondary leukemia), and to reduce therapy-related neutropenia (pilot studies POG 9086, 9295, 9296, 9297, 9398). All patients included in this analysis qualified for POG high risk criteria, WBC >50000/mm3 and/or CNS leukemia. Patients without CNS involvement received 16 doses of age-adjusted triple intra-thecal therapy (TIT = hydrocortisone, MTX, and cytarabine) whereas patients with CNS disease received three more doses of TIT during induction and consolidation. Patients who received CRT were treated with 2400 cGy (POG 8704) or 1800 cGy (POG 9086 and 9295). CNS therapy included CRT in 144 patients while the remaining 78 patients received no radiation by original protocol design. There were 155 males and 57 females with a median age of 8.2 years. The median WBC for the CRT+ and CRT- patients were 186000/mm3 and 200000/mm3, respectively. CNS involvement at diagnosis was seen in 16% of the CRT+ and 23% of the CRT- groups. The complete continuous remission rate (CCR) was not significantly different for the irradiated vs. non-irradiated groups (P = 0.46). The 3-year event-free survival was 65% (s.e. 6%) and 63% (s.e. 4%) for the non-irradiated vs. the radiated group. However, the 3-year CNS relapse rate was significantly higher amongst patients who did not receive CRT; 18% (s.e. 5%) vs. 7% (s.e. 3%) in the irradiated group (P = 0.012). Our analysis in a non-randomized setting, suggests that CRT did not significantly correlate with event-free survival but omitting it had an adverse effect on the CNS involvement at the time of relapse.

Burkitt lymphoma is immunophenotypically different from Burkitt-like lymphoma in young persons.

INTRODUCTION: Burkitt-like lymphoma (BLL) is a provisional category of B-cell lymphoma which is morphologically intermediate between Burkitt lymphoma (BL) and large B-cell lymphoma (LBCL). The clinical significance of this morphology is controversial. PATIENTS AND METHODS: We examined 41 cases of pediatric B-cell lymphoma by immunohistochemistry for proteins associated with proto-oncogenes c-myc, BCL-2 and BCL-6 and a subset of cases (with adequate slides) for a proliferation-associated marker (Ki-67) and for apoptosis (Apop-Tag). Sixteen cases of BLL, thirteen cases of BL and twelve cases of LBCL were examined. RESULTS: Our results showed BCL-6 expression in 16 of 16 BLL, 4 of 13 BL, and 9 of 12 LBCL; c-myc expression in 14 of 15 BLL, 9 of 13 BL, and 12 of 12 LBCL; and BCL-2 expression in 2 of 16 BLL, 9 of 13 BL, and 6 of 12 LBCL. Mean apoptotic index for BLL was 10.3% (n = 6); for BL was 17.1% (n = 5); and for LBCL was 10.9% (n = 6). Ki-67 was diffusely reactive in all cases tested. There was a significantly higher proportion of BLL than BL which expressed BCL-6 (P = 0.0001). CONCLUSIONS: Labeling for BCL-6 distinguishes BLL from BL. It is likely that in children in North America, BLL is biologically distinct from BL and more closely resembles a subset of LBCL.

Racial differences in the survival of childhood B-precursor acute lymphoblastic leukemia: a Pediatric Oncology Group Study.

PURPOSE: We conducted a historic cohort study to test the hypothesis that, after adjustment for biologic factors, African-American (AA) children and Spanish surname (SS) children with newly diagnosed B-precursor acute lymphoblastic leukemia had lower survival than did comparable white children. PATIENTS AND METHODS: From 1981 to 1994, 4,061 white, 518 AA, and 507 SS children aged 1 to 20 years were treated on three successive Pediatric Oncology Group multicenter randomized clinical trials. RESULTS: AA and SS patients were more likely to have adverse prognostic features at diagnosis and lower survival than were white patients. The 5-year cumulative survival rates were (probability +/- SE) 81.9% +/- 0.6%, 68.6% +/- 2.1%, and 74.9% +/- 2.0% for white, AA, and SS children, respectively. Adjusting for age, leukocyte count, sex, era of treatment, and leukemia blast cell ploidy, we found that AA children had a 42% excess mortality rate compared with white children (proportional hazards ratio [PHR] = 1.42; 95% confidence interval [CI], 1.12 to 1. 80), and SS children had a 33% excess mortality rate compared with white children (PHR = 1.33; 95% CI, 1.19 to 1.49). CONCLUSION: Clinical presentation, tumor biology, and deviations from prescribed therapy did not explain the differences in survival and event-free survival that we observed, although differences seem to be diminishing over time with improvements in therapy. The disparity in outcome for AA and SS children is most likely related to variations in chemotherapeutic response to therapy and not to compliance. Further improvements in outcome may require individualized dosing based on specific pharmacogenetic profiles, especially for AA and SS children.

Periacetabular osteotomy without abductor dissection using direct anterior exposure.

The direct anterior exposure is a new abductor sparing surgical approach to perform periacetabular osteotomy, developed in an effort to eliminate the postoperative abductor morbidity associated with the classic Smith-Petersen approach. The direct anterior exposure also allows anterior arthrotomy of the hip joint, necessary to deal with intraarticular disease of the acetabular rim that is common in adult patients who require periacetabular osteotomy. The direct anterior exposure combines the medial portion of the classic Smith-Petersen iliofemoral exposure with or without the second window of the ilioinguinal exposure. An osteotomy of the anterior superior spine is done routinely to facilitate the approach by relaxing the attached sartorius and inguinal ligament origins. The authors' experience with the direct anterior exposure involves 195 consecutive periacetabular osteotomies done since 1992, with 60 operations done using the full approach through two windows and 135 operations done using the limited approach through one window. There was no difference in functional or radiographic results, with both approaches allowing rapid functional recovery, excellent radiographic corrections, rapid bony healing, and minimal formation of heterotopic bone. No osteonecrosis or vascular injuries were seen. In nearly all patients, abductor function had returned to preoperative levels by 3 months after surgery, in distinct contrast to the authors' previous experience with the Smith-Petersen approach. The authors consider the direct anterior exposure to be the surgical approach of choice for periacetabular osteotomy, with the more limited version proving satisfactory in all patients except the largest and most muscular patients. The full version is useful in large male patients.