Not All Hip Dysplasias are the Same: Preoperative CT Version Study and the Need for Reverse Bernese Periacetabular Osteotomy.

BACKGROUND: Dysplastic hip may present with acetabular retroversion with or without femoral retroversion. This retroversion, if not accounted for when performing a periacetabular osteotomy (PAO), will lead to anterior hip pain and early osteoarthritis. A reverse PAO involves anteverting the acetabulum while still obtaining lateral coverage. The purpose of this study was to investigate the relationship between rotational malalignment of acetabulum and femur on 2-dimensional computed tomographic (CT) scans of hips that underwent Bernese PAO and its role in the surgical decision making. METHODS: This retrospective, case-control study examined and compared preoperative 2-dimensional CT scans of hips that underwent reverse PAO to the hips that underwent traditional PAO. RESULTS: Twelve hips underwent reverse PAO from 2005 to 2010. Twelve hips were randomly selected from a cohort of 52 hips that underwent traditional PAO during same time period. Hips that underwent reverse PAO showed crossover sign on preoperative radiographs, but not on postoperative radiographs. Crossover sign was negative preoperatively and postoperatively on hips that underwent traditional PAO. The 2 groups were similar in regards to preoperative lateral center-edge angle, acetabular index, and anterior center-edge angle on plain radiographs and showed significant improvement after surgery.On preoperative CT scans both acetabulae and femurs were retroverted in reverse PAO group. Comparison of the 2 groups demonstrated that acetabular version (16.5±4.9 degrees vs. 25.3±5.6 degrees, P=0.001), femoral version (12.8±10.4 degrees vs. 31.9±8 degrees, P<0.001), and McKibbins Instability Index (29.3±11.9 degrees vs. 57.1±9.8 degrees, P<0.001) were significantly lower for the reverse PAO than the traditional PAO group. Anterior Acetabular Sector Angle (determines anterior coverage) was significantly higher in reverse PAO group, 53.1±13.7 degrees versus 39.7±10.4 degrees (P=0.013). CONCLUSIONS: Retroverted acetabulae seem to be associated with reduced femoral version. Given that retroverted acetabulum and retroverted femur have additive effect and increase chances of anterior hip pain, preoperative identification of correct acetabular, and femoral version by CT scan or MRI is necessary to determine which hip need reverse PAO as opposed to traditional PAO. LEVEL OF EVIDENCE: Level III-Therapeutic.

Current Practice in the Management of Slipped Capital Femoral Epiphysis.

BACKGROUND: The most widely used treatment for slipped capital femoral epiphysis (SCFE) is in situ fixation. In an attempt to reduce the chances of impingement, osteoarthritis, and osteonecrosis, surgeons have started adopting newer surgical techniques. The purpose of this study was to determine the current pattern of treating SCFE. METHODS: A questionnaire was sent electronically to all of the members of the Pediatric Orthopaedic Society of North America. The data were analyzed dividing surgeons into academic versus private practice, years of practice, and number of SCFEs treated per year. RESULTS: Of 990 members, 277 (28%) responded to the survey.Type of practice (academic, n=181 vs. private, n=51): For unstable severe SCFE, surgeons in academic practice use the surgical hip dislocation (SHD) approach significantly more frequently (35.7% vs. 14.9%; P=0.02). A radiolucent table is used significantly more frequently in academic practice for both stable (50.6% vs. 29.8%; P=0.01) and unstable (39.6% vs. 15.2%; P=0.002) SCFE. Fully threaded cannulated screws (44.4% vs. 27.1%; P=0.03), open capsular decompression (63.9% vs. 32.4%; P=0.001), contralateral pinning (79% vs. 58.7%; P=0.005), and postoperative magnetic resonance imaging (MRI) (15.5% vs. 3.9%; P=0.03) are significantly more frequent in academic practice.Years of practice (≤15 y, n=124 vs. >15 y, n=140): For severe stable SCFE, surgeons practicing for ≤15 years do acute osteotomies significantly less frequently (1.8% vs. 9%; P=0.004) and perform SHD significantly more frequently (20.2% vs. 8.2%; P=0.004). For unstable moderate SCFE, SHD is utilized significantly more frequently by surgeons ≤15 years in practice (29.8% vs. 16.5%; P=0.04). Bilateral frog-leg lateral views (86.4% vs. 73.7%; P=0.04), preoperative MRI (36.1% vs. 20.6%; P=0.006), open capsular decompression (69.3% vs. 51.7%; P=0.01) are significantly more frequent among surgeons ≤15 years in practice.Number of SCFE treated per year (<10, n=129 vs. ≥10, n=136): For unstable severe SCFE, surgeons treating ≥10/y perform SHD significantly more frequently (38.6% vs. 26.1%; P=0.02) and do in situ fixation with manual reduction significantly less frequently (11.8% vs. 21.8%; P=0.02). Radiolucent table (54.3% vs. 38%; P=0.01), 7.5 mm screw versus 6.5 mm (62% vs. 45.4%; P=0.01), contralateral pinning (78.9% vs. 67.8%; P=0.04), postoperative MRI (17.6% vs. 9.3%; P=0.04), and postoperative computed tomography (14.7% vs. 7%; 0.04) are significantly more frequent among surgeons doing ≥10/y. Elective implant removal is more common among surgeons treating <10/y (16.2% vs. 6.9%; P=0.02). CONCLUSIONS: Treatment of SCFE varies significantly depending on the surgeon's type of practice, years in practice, and numbers treated per year. Surgeons in academic practice, surgeons with ≤15 years in practice, and surgeons treating greater number of SCFEs are more likely to use SHD to acutely reduce the slip.

Hip dysplasia in patients with Hurler syndrome (mucopolysaccharidosis type 1H).

BACKGROUND: Hip dysplasia is common in patients with Hurler syndrome (HS). However, its prevalence and optimal management is not yet clear because of the rarity of the disease and the prior short life span of these patients. Recent advances in the management of these children using allogeneic hematopoietic cell transplant (HCT) has significantly increased their life expectancy, with many surviving into adulthood. This review was conducted to describe the experience of a single center with hip dysplasia in HS after HCT. METHODS: We performed a retrospective review of hip dysplasia in a consecutive series of patients with HS treated with HCT from 1985 to 2008. RESULTS: At 4.5 (± 2.9) years after HCT all 51 children (102 hips) with HS showed acetabular dysplasia and proximal femur valgus deformity. Mean age at HCT was 1.6 ± 0.9 years. Forty hips (39%) underwent hip reconstructive osteotomies at mean age of 6.8 ± 3.1 years. Significant radiographic improvement was noted in all radiographic parameters at 5.4 ± 3.7 years after hip surgery (P<0.001). Acetabular index improved from 33.3 degrees (± 7.9) preoperative to 24.7 degrees (± 8) after surgery, lateral center edge angle improved from -5.3 degrees (± 10.9) to 35.2 degrees (± 17.8), migration index from 50.7% (± 15.7) to 9.6% (± 13.6), and femoral-neck-shaft angle from 150.9 degrees (± 5.8) to 130.8 degrees (± 12.4). Ten of the 40 hips underwent only proximal femoral varus derotation osteotomy and 30 underwent combined proximal femoral varus derotation osteotomy+pelvic osteotomy. CONCLUSIONS: This study reports high prevalence of hip dysplasia (100%) in patients with HS. As significant radiographic improvement was achieved in those patients treated with surgical interventions we recommend annual orthopaedic evaluation of hips in patients with HS after HCT and intervention with reconstructive femoral and pelvic osteotomies for their hip dysplasia.

Predictors of emotional functioning in youth after surgical correction of idiopathic scoliosis.

BACKGROUND: Patients with idiopathic scoliosis, although otherwise healthy, often have significant concerns about their self-image and appearance. In a group of juveniles and adolescents, this can impact adjustment in school, functioning in peer groups, and general sense of well-being. There are limited data to help physicians reliably and precisely identify those who are at higher risk of poor emotional adjustment even after spine deformity correction. The purpose of this study was to determine the predictors of emotional maladjustment in juvenile and adolescent patients after surgical correction of idiopathic scoliosis. METHODS: A total of 233 juveniles, mean age 11.26 ± 1.02 (range, 8 to 12) years and 909 adolescents, mean age 14.91 ± 1.61 (range, 13 to 21) years, who underwent surgical correction for idiopathic scoliosis and who were participating in a prospective longitudinal multicenter database, were enrolled in the study. Participants completed the Scoliosis Research Society-22 (SRS-22) questionnaire before surgery and 2 years postoperatively. Radiographs were used to measure Cobb angle and surface measurements were used to determine decompensation and trunk shift. RESULTS: Adolescents reported poorer mental health preoperatively (P<0.05) and 2 years postoperatively (P<0.001) than juveniles; however, both groups reported improved mental health (P<0.001) and self-image (P<0.01) postoperatively. Mental health 2 years postoperatively was predicted by preoperative self-image (P<0.05), mental health (P<0.001), and main thoracic Cobb angle (P<0.05) in the juvenile group. Within the adolescent group, mental health 2 years postoperatively was predicted by preoperative mental health (P<0.001); self-image 2 years postoperatively was predicted by preoperative mental health (P<0.01) and self-image (P<0.001). CONCLUSIONS: Self-image and mental health are significantly improved after spine deformity correction in juveniles and adolescents with idiopathic scoliosis. However, consistent with normative development, adolescents are at higher risk for emotional maladjustment than juveniles. Surgical decision making in scoliosis correction should take the emotional status of the patient into consideration.

Rectus femoris transfer improves stiff knee gait in children with spastic cerebral palsy.

BACKGROUND: Stiff knee gait is common among children with ambulatory cerebral palsy (CP). When surgery is indicated, rectus femoris transfer as a primary treatment enhances knee range of motion, reduces time to peak knee flexion, increases peak knee flexion, and reduces toe drag. QUESTIONS/PURPOSES: We determined whether (1) distal rectus femoris transfer improved knee range of motion, time to peak knee flexion, peak knee flexion, and toe drag in children with CP diagnosed with stiff knee gait; and (2) patients in some subgroups (eg, those with relatively high knee range of motion compared with those with low knee range of motion before rectus femoris transfer) had greater improvement in these parameters. METHODS: We retrospectively reviewed gait data from 56 patients (99 limbs) preoperatively, short-term, and long-term. Subgroup analyses were performed to determine whether patients with high knee range of motion relative to those with low or moderate knee range of motion improved differentially after rectus femoris transfer. The minimum followup was 7 years (mean ± SD, 10 ± 2 years; range, 7-13 years). RESULTS: The mean peak knee flexion increased from baseline to short-term and to long-term followup. Patients with low peak knee flexion had the greatest improvement of peak knee flexion after rectus femoris transfer relative to the moderate and high peak knee flexion subgroups. Similarly, the greatest improvement after rectus femoris transfer for knee range of motion occurred in the low knee range of motion subgroup relative to moderate and high subgroups. Rectus femoris transfer improved mean time to peak knee flexion at short-term and long-term followup compared with baseline. Likewise, there was a decrease in toe drag at short- and long-term after rectus femoris transfer. CONCLUSION: Distal rectus femoris transfer selectively improved peak knee flexion, toe drag, and reduced time to peak knee flexion in ambulatory children with CP with stiff knee gait. LEVEL OF EVIDENCE: Level IV, therapeutic study. See guidelines for authors for a complete description of levels of evidence.

Reliability and necessity of computerized tomography in distal tibial physeal injuries.

OBJECTIVE: Complex distal tibial physeal fractures can be difficult to characterize on plain radiographs. The role of computed tomography (CT) scans in the evaluation and treatment decision of these injuries is unclear. We aimed to determine whether or not the addition of CT would improve the reliability of fracture classification and treatment decision. METHODS: Five independent observers evaluated 50 distal tibial physeal fractures on 2 separate occasions for Salter Harris (SH) classification and treatment decision (surgical/nonsurgical) using plain radiographs (round 1) and combination of radiographs and CT (round 2). During round 1, observers were asked if they would order a CT, and during round 2, they were asked if the CT was useful. These rounds were repeated at 2 to 4 weeks to assess intraobserver reliability. Statistical analyses were performed to assess inter and intraobserver reliability using Kappa coefficient (κ). RESULTS: Intraobserver reliability for SH classification showed substantial agreement, κ=0.76 and κ=0.80, respectively, during round 1 and 2. Interobserver agreement on the SH class was lower during round 1 and 2 (κ=0.67 and κ=0.57, respectively). There also was almost perfect intraobserver and interobserver agreement in the measurement of displacement at the fracture site during both rounds 1 and 2. Intraobserver reliability for treatment decision was substantial, κ=0.74 and κ=0.80, respectively, during round 1 and 2. However, interobserver agreement for treatment decision was moderate (κ=0.48) and fair (κ=0.36), respectively, during round 1 and 2. Surgeons indicated that they would like to order CT scans for 66% of the time in round 1, but the interobserver agreement as to who would best benefit from the CT was only fair (κ=-0.23). The main purpose of ordering the CT was to delineate fracture anatomy (55% of the time) and the observers felt CT would add to their treatment decision only 26% of the time. During round 2, 75% of time surgeons felt that CT scan was useful. CT was thought to be most useful in guiding screw placement (56% of the time) and not as useful (28% of time) for treatment decision making. CONCLUSIONS: Addition of CT in complex distal tibial physeal fractures did not increase interobserver reliability to classify the fracture or the treatment decision. Surgeons reported that the CT was most useful to plan screw placement and changed their treatment decision in about a fifth of the cases.

Inclusion of L5-S1 in oblique lumbar interbody fusion-techniques and early complications-a single center experience.

BACKGROUND CONTEXT: The oblique prepsoas retroperitoneal approach to the lumbar spine for interbody fusion or oblique lumbar interbody fusion (OLIF) provides safe access to nearly all lumbar levels. A wide interval between the psoas and aorta allows for a safe and straightforward left-sided oblique approach to the discs above L5. Inclusion of L5-S1 in this approach, however, requires modifications in the technique to navigate the complex and variable vascular anatomy distal to the bifurcation of the great vessels. While different oblique approaches to L5-S1 have been described in the literature, to our knowledge, no previous study has provided guidance for the choice of technique. PURPOSE: Our objectives were to evaluate our early experience with the safety of including L5-S1 in OLIF using 3 different approach techniques, as well as to compare early complications between OLIF with and without L5-S1 inclusion. STUDY DESIGN: Retrospective cohort study. PATIENT SAMPLE: Of the 87 patients who underwent lumbar interbody fusion at 167 spinal levels via an OLIF approach, 19 included L5-S1 (group A) and 68 did not (group B). OUTCOME MEASURES: Demographics, levels fused, indications, operative time (ORT), estimated blood loss (EBL), vascular ligation, intraoperative blood transfusion, length of stay (LOS), discharge to rehabilitation facility, and complications (intraoperative, early ≤90 days, and delayed >90 days) were retrospectively assessed and compared between the groups. METHODS: A retrospective chart and imaging review of all consecutive patients who underwent OLIF at a single institution was performed. Indications for OLIF included symptomatic lumbar degenerative stenosis, deformity, and spondylolisthesis. The L5-S1 level, when included, was approached via one of the following 3 techniques: (1) a left-sided intrabifurcation approach; (2) left-sided prepsoas approach; and (3) right-sided prepsoas approach. Vascular anatomic variations at the lumbosacral junction were evaluated using the preoperative magnetic resonance imaging (MRI), and a "facet line" was proposed to assess this relationship. A minimum of 6 months of follow-up data were assessed for approach-related morbidities. RESULTS: Demographics and operative indications were similar between the groups. The mean follow-up was 10.8 (6-36) months. ORT was significantly longer in group A than in group B (322 vs. 256.3 min, respectively; p=.001); however, no difference in ORT between the two groups was found in the subanalyses for 2- and 3-level surgeries. Differences in EBL (260 vs. 207.91 cc, p=.251) and LOS (2.76 vs. 2.48 days, p=.491) did not reach statistical significance. Ligation of the iliolumbar vein, segmental veins, median sacral vessels, or any vascular structure, as needed for adequate exposure, was required in 13 (68.4%) patients from group A and 4 (5.9%) from group B (p<.00001). Two patients suffered minor vascular injuries (1 in each group); however, no major vascular injuries were seen. Complications were not significantly different between groups A and B, or between the three approaches to L5-S1, and trended lower in the latter part of the series as the learning curve progressed. CONCLUSIONS: Inclusion of L5-S1 in OLIF is safe and feasible through three different approaches but likely involves greater operative complexity. In our early experience, inclusion of L5-S1 showed no increase in early complications. This is the first series that reports the use of 3 different oblique approaches to L5-S1. The proposed "facet line" in the preoperative MRI may guide the choice of approach.

Bilaterally dislocated hips treated with the Pavlik harness are not at a higher risk for failure.

BACKGROUND: The purpose of this study is to evaluate the efficacy of the Pavlik harness treatment in patients with bilaterally dislocated hips, and to compare them with cases with unilaterally dislocated hips. METHODS: Twenty-nine patients (58 hips) were identified who presented with bilateral dislocated hips with no earlier treatment and received dynamic ultrasound examination. The comparison group consisted of 38 patients (38 hips) with unilateral hip dislocation treated with the same protocol. Successful treatment was defined as relocation/reduction of the hips within 3 weeks of Pavlik harness application. RESULTS: Seventeen of 29 patients (59%) in the bilateral group (7 bilateral, 10 unilateral) and 22 of 38 patients (58%) in the unilateral group failed the harness treatment. There was no difference in the duration of harness wear for successful patients regardless of presentation. CONCLUSIONS: Patients presenting with bilaterally dislocated hips treated with the Pavlik harness are at no greater risk for failure than patients presenting with unilateral hip dislocation. LEVEL OF EVIDENCE: Level 3.

Successful treatment of unicameral bone cyst by single percutaneous injection of alpha-BSM.

BACKGROUND: Unicameral bone cyst (UBC) is a benign bone lesion, recognized for its high rate of recurrence and need for repeat procedures to achieve healing. We hypothesized that the osteoconductive material apatitic calcium phosphate (alpha-BSM) could be effective in filling and stimulating resolution of UBC. The purpose of this study was to evaluate clinical and radiographic outcomes of UBC treated by a single injection of alpha-BSM. METHODS: Thirteen patients (6 male, 7 female) with a mean age of 10.5 years, underwent single percutaneous injection of alpha-BSM for presumed UBC. The aspiration of the cysts was followed by vigorous saline lavage using 2 wide bore needles to disrupt the cyst walls. alpha-BSM "paste" was then injected under fluoroscopic guidance. Radiographs were digitized to measure cystic area (millimeter squares) on 2 orthogonal views. Healing was rated according to a modified Neer outcome grading system. Nine of the 13 patients had had pathologic fractures in the past. Eleven of the 13 patients had had past unsuccessful treatment: multiple steroid injections in 6, curettage and bone grafting in 3, and bone marrow and demineralized bone matrix (Grafton) injection in 2. RESULTS: Five cysts were grade 1 (healed 100%), 6 grade 2 (healed >50%), 2 grade 3 (healed <50% with increased cortical thickness), and none grade 4 (recurrence/enlargement). The average resolution of cystic area in 11/13 cysts was 85.7% at final follow-up of 35.8 months (P=0.0001) with 2.8 mm of average gain in cortical thickness (P=0.0018). None of the 13 lesions required an additional procedure or repeat injection. All patients were clinically asymptomatic at latest follow-up. CONCLUSIONS: This is the first study quantifying cyst resolution objectively according to actual decrease in area (millimeter squares). A single injection of alpha-BSM is a safe, minimally invasive and efficacious method to treat UBC in the pediatric population.

Diagnosing Sacroiliac Joint Pain.

The sacroiliac joint (SIJ) is a diarthrodial joint that has been implicated as a pain generator in approximately 10% to 25% of patients with mechanical low back or leg symptoms. Unique anatomic and physiologic characteristics of SIJ make it susceptible to mechanical stress and also create challenges in the diagnosis of SIJ pain. A variety of inciting causes for SIJ pain may exist, ranging from repetitive low-impact activities such as jogging to increased stress after multilevel spine fusion surgery to high-energy trauma such as in motor vehicle accidents. Similarly, wide variability exists in the clinical presentation of SIJ pain from localized pain or tenderness around the SIJ to radiating pain into the groin or even the entire lower extremity. No pathognomonic clinical history, physical examination finding, or imaging study exists that aids clinicians in making a reliable diagnosis. However, imaging combined with clinical provocative tests might help to identify patients for further investigation. Although provocative physical examination tests have not received reliable consensus, if three or more provocative tests are positive, pursuing a diagnostic SIJ injection is considered reasonable. Notable pain relief with intra-articular anesthetic injection under radiographic guidance has been shown to provide reliable evidence in the diagnosis of SIJ pain.

Transverse process hooks at upper instrumented vertebra provide more gradual motion transition than pedicle screws.

STUDY DESIGN: Biomechanical study in a porcine model. OBJECTIVE: To determine whether transverse process hooks (TPHs) placed at the proximal end of a long posterior spinal fusion construct provide a more gradual transition to normal motion of the adjacent cephalad motion segment compared with an all pedicle screw (APS) construct. SUMMARY OF BACKGROUND DATA: Proximal junctional kyphosis after instrumentation with long posterior spinal constructs has been increasingly associated with incidence of adjacent segment pathologies. Clinical studies have suggested that proximal anchor type may affect the incidence of proximal junctional kyphosis. METHODS: Biomechanical tests were conducted on porcine thoracic spines before and after implantation of a long spinal fusion construct. In all specimens, dual long rods (Co-Cr) were implanted posteriorly using pedicle screws at T7-T15. Upper instrumented vertebra, T6, received either TPHs (n = 7) or pedicle screws (APSs) (n = 6). Each specimen was tested in flexion-extension then lateral bending. Moments were applied, and vertebral displacements were recorded. Range of motion (ROM) and stiffness (K) were determined for each motion segment. Differences between TPH and APS at the transition were determined using t tests. RESULTS: In flexion-extension, ROM at the most proximal instrumented motion segment was 9% of control for APS versus 21% of control for TPH. Difference between APS and TPH at UIV was 0.5° (P < 0.008). Stiffness of TPH at T6-T7 was significantly lower than APS in FE (P < 0.003). For APS, the greatest mean ROM occurred at the first uninstrumented segment, whereas TPH maintained the pattern of monotonic increases in mean ROM from distal to proximal. CONCLUSION: TPHs at the upper instrumented vertebra provided a more gradual transition to normal motion compared with pedicle screws in long posterior spinal fusion constructs. TPH at the upper instrumented vertebra may be postulated to decrease the incidence of postoperative proximal junctional kyphosis compared with APS. LEVEL OF EVIDENCE: N/A.

Accuracy and Reliability of Drawing Central Sacral Vertical Line on Scoliosis Radiographs in Clinical Practice.

STUDY DESIGN: Retrospective cross-sectional assessment of radiographs of adolescent idiopathic scoliosis. OBJECTIVE: To assess accuracy, reliability, and reproducibility of the central sacral vertical line (CVSL) on scoliosis radiographs and its influence on determining clinically relevant parameters: stable vertebra (SV) and lumbar modifier (LM). BACKGROUND SUMMARY: The central sacral vertical line is frequently used on scoliosis radiographs for surgical planning. However, no studies have assessed how accurately and reliably a physician draws CSVL in routine clinical practice. METHODS: We provided 30 digital posteroanterior X-rays of adolescent idiopathic scoliosis to 5 raters (3 fellowship-trained spine surgeons and 2 fellows) at 2 different times (3-week interval) to determine SV and LM. An independent observer then assessed the accuracy of CSVL drawn by the raters. The CSVL was considered accurate when it was drawn vertical from the middle of the S1 vertebra. To avoid conscious bias, we kept raters blinded as to the actual purpose of the study. To avoid technical bias, the study was conducted with research Picture Archiving and Communication Systems (PACS) software and raters used desktop computers similar to those in clinics or operating rooms. RESULTS: Based on absolute values, the CSVL was drawn on average 2.3 (±1.9) mm away from the center. Based on raw values, the lines were drawn on average 1.0 (±2.8) mm left of the center. We observed fair inter-rater reliability among the 5 raters, with an intra-class correlation of 0.23 (95% confidence interval, -0.33-0.59). Intra-rater reproducibility was moderate across 2 assessments, with an ICC of 0.47 (95% confidence interval, 0.27-0.62). Variation in drawing CSVL from center was not significantly associated with the selection of SV (r=-0.02; p=.78) or LM (r=-0.02; p=.78). CONCLUSION: Although, physicians draw CSVL significantly away from the center of the S1 vertebra (mean, 2.3 mm), its influence on determining SV or LM is not affected in routine practice.

Complications associated with the Bernese periacetabular osteotomy for hip dysplasia in adolescents.

BACKGROUND: The Bernese (Ganz) periacetabular osteotomy is an effective surgical procedure to reorient the acetabulum, allowing restoration of anatomic femoral head coverage and medial translation of the hip in adults with hip dysplasia. However, it is a challenging surgical procedure, and we know of no study that has specifically analyzed the complications and associated factors seen with this procedure in adolescent patients. METHODS: A retrospective clinical and radiographic review of a consecutive series of adolescent patients who underwent a Bernese periacetabular osteotomy for hip dysplasia was conducted. RESULTS: Eighty-three osteotomies were performed in seventy-six patients with an average age (and standard deviation) of 15.6 +/- 2.4 years. Significant improvement from the preoperative to the two-year follow-up evaluation was seen radiographically with regard to the lateral center-edge angle (-0.14 degrees to 35.5 degrees), the ventral center-edge angle (-5.13 degrees to 31.3 degrees), and the femoral head extrusion index (38.4% to 7.7%) (p < 0.0001 for all). There were three major complications, including excessive arterial bleeding requiring embolization in a patient with a prior acetabuloplasty, osteonecrosis of the acetabular fragment in a patient with severe dysplasia and subluxation of the hip, and osteonecrosis of the femoral head following combined periacetabular and femoral osteotomies in a patient with Charcot-Marie-Tooth disease. Eighteen hips (22%) had minor complications, including nonunion of the superior pubic ramus osteotomy (five hips), a superficial stitch abscess (four), and transient lateral femoral cutaneous nerve palsy (four). Nine hips (11%) underwent removal of symptomatic screws, and two required a second operation to reposition the acetabular fragment. An underlying diagnosis other than developmental dysplasia increased the prevalence of minor complications (p = 0.0017), while a major complication was more likely with longer surgery time, greater blood loss, and proximal femoral osteotomy. CONCLUSIONS: The Bernese periacetabular osteotomy is a joint-preserving procedure that very effectively corrects acetabular dysplasia in adolescent patients, providing improved radiographic results and a low rate of complications. Although the rate of minor complications is increased when there is an underlying diagnosis other than developmental dysplasia, no other predictors were identified. However, a major complication is more likely with a longer duration of surgery and with a concomitant femoral varus osteotomy.