Wudbhav N. Sankar

Comparison of Complications Among Growing Spinal Implants

Study Design. Retrospective review. Objective. To evaluate the complication rate of various types of growing spinal implants. Summary of Background Data. Previous studies report a complication rate of 0.38 to 1.19 per patient in growing spine surgery, but this may be an underestimate. Methods. Medical records of 36 children with early-onset spinal deformity treated with various types of growing implants by a single surgeon were evaluated for complications. Patients with primary chest wall deformities were excluded. Complications were defined as any neurologic injuries, and any unplanned surgeries for implant failure or infection. Patients were separated into 3 groups: (A) standard dual growing rods, (B) hybrid growing rods with rib anchors proximally and spine anchors distally, and (C) VEPTR (vertical expandable prosthetic titanium rib). Statistical analyses were performed to compare the complication rate among the 3 groups and to evaluate the effect of Cobb angle, kyphosis, age, and body mass index on the complication rate. Results. Mean age at initial implantation was 4.8 years; mean follow-up was 51 months (24–117 months). A total of 72 unplanned surgeries occurred in 26 out of 36 patients (72%), including 18 revisions for rod breakage, 31 revisions for migrated anchors, and 18 irrigations and debridements for infection. Two children (5.6%) developed a neurologic deficit that required implant removal. Group A had 23 complications in 10 patients, with a complication rate of 2.3 per patient; group B had 6 complications in 7 patients, with a rate of 0.86 per patient; and group C had 45 complications in 19 patients, with a rate of 2.37 per patient. There was no significant difference between the 3 groups in terms of preoperative Cobb angle, kyphosis, age, and body mass index; these factors did not seem to influence the complication rate. Conclusion. To our knowledge, this is the first study directly comparing the complication rates of various types of growing spine implants. The complication rate in growing spine surgery is uniformly high but varies by implant type, with a trend toward fewer complications in hybrid constructs.

Loss of pin fixation in displaced supracondylar humeral fractures in children: causes and prevention.

BACKGROUND Although the results are generally good following pin fixation of supracondylar humeral fractures in children, occasionally there is postoperative displacement. The purposes of the present study were to identify the causes leading to loss of fixation after pin fixation and to present methods for prevention. METHODS We evaluated 322 displaced supracondylar humeral fractures that had been treated with percutaneous pin fixation. We examined fracture classification, pin configuration, intraoperative alignment after fixation, change in alignment after fixation, details of additional procedures, and final radiographic and clinical outcomes. RESULTS Adequate radiographs were available for 279 of the 322 fractures. Eight (2.9%) of the 279 fractures were associated with postoperative loss of fixation; all eight were Gartland type-III fractures. Seven of these eight fractures initially had been treated with two lateral-entry pins, and one had been treated with two crossed pins. In patients with Gartland type-III fractures, loss of fixation was successfully avoided more often when three pins were used (with fixation being maintained in thirty-seven of thirty-seven patients) as opposed to when two lateral-entry pins were used (with fixation being maintained in thirty-five of forty-two patients) (p = 0.01). In all cases, loss of fixation was due to technical errors that were identifiable on the intraoperative fluoroscopic images and that could have been prevented with proper technique. We identified three types of pin-fixation errors: (1) failure to engage both fragments with two pins or more, (2) failure to achieve bicortical fixation with two pins or more, and (3) failure to achieve adequate pin separation (>2 mm) at the fracture site. CONCLUSIONS Postoperative displacement following pin fixation of supracondylar humeral fractures in children is uncommon. In the present series, loss of fixation was most likely to occur when Gartland type-III fractures were treated with two lateral-entry pins. There were no failures when three pins were used. In all cases of failure, there were identifiable technical errors in pin placement. LEVEL OF EVIDENCE Therapeutic Level III. See Instructions to Authors for a complete description of levels of evidence.

Percutaneous intramedullary decompression, curettage, and grafting with medical-grade calcium sulfate pellets for unicameral bone cysts in children: a new minimally invasive technique.

Several treatment options exist for unicameral bone cysts (UBCs), including observation, steroid injection, bone marrow injection, and curettage and bone grafting. These are all associated with high recurrence rates, persistence, and occasional complications. Newer techniques have been described, most with variable success and only short follow-up reported. Because of these factors, a new minimally invasive percutaneous technique was developed for the treatment of UBCs in children. Twenty-eight children with UBCs who underwent percutaneous intramedullary decompression, curettage, and grafting with medical-grade calcium sulfate (MGCS) pellets by the senior author (J.P.D.) between April 2000 and April 2003 were analyzed as part of a pediatric musculoskeletal tumor registry at a large tertiary childrens hospital. Four patients were lost to follow-up, and the remaining 24 patients had an average follow-up of 21.9 months (range 4-48 months). Twelve patients were followed for at least 24 months. Six of the 24 children had received previous treatment of their UBC, most often at an outside institution. Follow-up was performed through clinical evaluation and radiographic review. Postoperative radiographs at most recent follow-up showed complete healing, defined as more than 95% opacification, in 22 of 24 patients (91.7%). One patient (4.2%) demonstrated partial healing, defined as 80% to 95% opacification. One patient had less than 80% radiographic healing (4.2%). All 24 patients returned to full activities and were asymptomatic at most recent follow-up. The only complication noted was a superficial suture abscess that occurred in one patient; this resolved with local treatment measures. The new minimally invasive technique of percutaneous intramedullary decompression, curettage, and grafting with MGCS pellets demonstrates favorable results with low complication and recurrence rates compared with conventional techniques. The role of intramedullary decompression as a part of this percutaneous technique is discussed.

The modified Dunn procedure for unstable slipped capital femoral epiphysis: a multicenter perspective.

BACKGROUND The modified Dunn procedure has rapidly gained popularity as a treatment for unstable slipped capital femoral epiphysis (SCFE), but limited data exist regarding its safety and efficacy. The purpose of this study was to present results and complications following this procedure in a large multicenter series. METHODS We reviewed the outcomes of all patients who had been treated with the modified Dunn procedure by five surgeons from separate tertiary-care institutions. All slipped capital femoral epiphyses were defined as unstable according to the Loder criteria. Patients with less than one year of follow-up and those with an underlying endocrinopathy or syndrome were excluded. All surgical procedures were performed by pediatric orthopaedic surgeons who had specific training in the modified Dunn procedure. Operative reports, outpatient records, and follow-up radiographs were used to determine the demographic information, type of fixation, final slip angle, presence of osteonecrosis, and any additional complications. Standardized surveys were administered to determine the pain level (0 to 10 scale), satisfaction (0 to 100 scale), function (modified Harris hip score, 0 to 91 scale), and activity level (UCLA [University of California Los Angeles] activity score, 0 to 10 scale) at time of the most recent follow-up. RESULTS Twenty-seven patients (twenty-seven hips) with a mean of 22.3 months (range, twelve to forty-eight months) of follow-up met the inclusion criteria. Four patients (15%) had broken implants at three to eighteen weeks after surgery and required revision fixation. Seven patients (26%) developed osteonecrosis at a mean of 21.4 weeks (range, ten to thirty-nine weeks), with each surgeon having at least one case of osteonecrosis. The mean slip angle at the time of the most recent follow-up was 6° (95% confidence interval, 2° to 11°). Patients who did not develop osteonecrosis had significantly better clinical results compared with those who developed osteonecrosis, as demonstrated by a lower mean pain score (0.3 compared with 3.1, p = 0.002), higher level of satisfaction (97.1 compared with 65.8, p = 0.001), higher modified Harris hip score (88.0 compared with 60.0, p = 0.001), and higher UCLA activity score (9.3 compared with 5.9, p = 0.031). CONCLUSIONS This largest reported series of unstable slipped capital femoral epiphyses treated with the modified Dunn procedure demonstrated that the procedure is capable of restoring anatomy and preserving function after a slip but that implant complications and osteonecrosis can and do occur postoperatively.

Femoroacetabular impingement: Defining the condition and its role in the pathophysiology of osteoarthritis

&NA; Femoroacetabular impingement (FAI) is an increasingly recognized cause of hip pain. It is best defined as a pathologic mechanical process by which morphologic abnormalities of the acetabulum and/or femur combined with vigorous hip motion lead to repetitive collisions that damage the soft‐tissue structures within the joint itself. Based on cross‐sectional studies in which FAI morphology was studied before the presence of radiographic osteoarthritis (OA), and on prevalence studies in younger, asymptomatic persons, it is clear that FAI and its morphologic risk factors are common in young adult hips and predispose to the later development of OA in certain patients. Longitudinal studies also support the assertion that, in middle‐aged adults, the presence of cam deformities at baseline substantially increases the risk of developing OA and the need for total hip arthroplasty. More longterm data are needed to better define the natural history of pincer deformities as well as FAI in younger cohorts.

Os odontoideum revisited : The case for a multifactorial etiology

Study Design. Retrospective analysis of our experience with os odontoideum at the Children’s Hospital of Philadelphia. Objective. To review the origin of os odontoideum and provide evidence for two separate etiologies. Summary of Background Data. The etiology of os odontoideum has been debated in the literature. Most authors support a post-traumatic etiology; however, some evidence exists to support a congenital origin. Methods. We reviewed all 519 abnormal cervical spine radiographs performed from 1991 to 2004 to identify os odontoideum. Medical records and imaging studies were examined to determine: history of trauma, severity of injury, interval from injury to presentation, coexisting syndromes, and associated congenital cervical spine anomalies. Results. Sixteen of 519 patients (3.1%) had os odontoideum. Only 8 of 16 patients reported previous trauma. Only 3 of these 8 injuries occurred with an interval remote enough to allow remodeling of the dens to an ossicle by the time of presentation. Six of 16 patients had associated congenital anomalies in the cervical spine. Three of 16 had a coexisting genetic syndrome. Conclusion. Our data supports two separate etiologies for the os odontoideum: post-traumatic and congenital. The data should raise awareness that some children with preexisting syndromes may develop os odontoideum without previous trauma.

Adjunctive vancomycin powder in pediatric spine surgery is safe.

Study Design. Therapeutic level II cohort study. Objective. To evaluate the safety of adjunctive local application of vancomycin powder (VP) for infection prophylaxis in posterior instrumented thoracic and lumbar spine wounds in pediatric patients weighing more than 25 kg. Summary of Background Data. Spine surgeons have largely turned to vancomycin prophylaxis in an attempt to decrease the incidence of late surgical site infection and acute surgical site infection from methicillin-resistant Staphylococcus aureus. In adult patients, the adjunctive local application of VP with an intravenous cephalosporin has been shown to decrease postsurgical wound infection rates significantly; however, the safety of VP as an adjunct in pediatric spine surgery has not been reported. Methods. We reviewed data collected under a systematic protocol specifically designed to monitor the safety profile of VP. We measured changes in creatinine and systemic vancomycin levels after intrawound application of 500 mg of unreconstituted VP during spine deformity correction surgery in patients weighing more than 25 kg (patients also received routine intravenous cephalosporin prophylaxis). Laboratory values were measured preoperatively and on postoperative days 1 and 4. Any adverse reactions and infections through available follow-up (2–8 mo) were recorded. Results. Eighty-seven consecutive pediatric patients with spinal deformity weighing more than 25 kg who received intraoperative VP during a 9-month period were identified. Sixty-three percent of the patients in this series had adolescent idiopathic scoliosis, 15% congenital scoliosis, 15% neuromuscular scoliosis, and 5% spondylolisthesis. The average change in creatinine levels between the preoperative and postoperative day 1 draw was −0.03 and between the preoperative and postoperative day 4 draw was −0.075. The postoperative systemic vancomycin levels remained undetectable. None of the patients experienced nephrotoxicity or red man syndrome. Three of the 87 patients developed a surgical site infection. Conclusion. In this cohort there were no clinically significant changes in creatinine level or systemic vancomycin level caused by use of intraoperative VP. Level of Evidence: 2

Acetabular Morphology in Slipped Capital Femoral Epiphysis

Background Children with unilateral slipped capital femoral epiphysis (SCFE) often appear to have overcoverage of their contralateral (normal) side. This increased coverage can be a contributing factor to femoroacetabular impingement. The purpose of this study was to quantify the coverage of the normal hip in patients with unilateral SCFE and to compare our results to matched controls. Methods Between 2003 and 2008, we identified 50 patients treated for unilateral, stable SCFE by in-situ screw fixation. Using postoperative anteroposterior and frog radiographs of the pelvis, the lateral center-edge angle (LCEA) and Tönnis angle (TA) were measured on the uninvolved side. Pelvic tilt was evaluated to ensure the quality of the radiographs, and in those patients with appropriate films, the presence or absence of a posterior wall sign and cross-over sign was noted. Results were compared with 50 age and sex-matched controls. Control data was generated from scout views of otherwise healthy patients who underwent an abdominal computed tomography scan to rule out acute appendicitis. Results The mean LCEA and TA of the contralateral acetabulum were 33 and 5 degrees, respectively (range: 18 to 47; −7 to 13). Seventy-eight percent had a positive cross-over sign and 39% had a posterior wall sign. In comparison, the mean LCEA and TA in our control group were 20 and 8 degrees, respectively (range: 8 to 35; −6 to 23). In this group, 21% had a positive cross-over sign whereas 15% had a positive posterior wall sign. We found a significantly higher LCEA and lower TA in the study population compared with controls (P=1.6E-16, 0.0003), as well as a higher prevalence of retroversion signs (P=5E-7, 0.02). Conclusions The contralateral acetabulum in patients with treated unilateral SCFE demonstrates significantly more coverage compared with matched controls. In addition, there is a significantly higher prevalence of acetabular retroversion in these patients. Our findings should alert caregivers to the potential of developing femoroacetabular impingement on the contralateral side in patients who have had a unilateral SCFE. Levels of Evidence III (retrospective case-control).

The Unstable Slipped Capital Femoral Epiphysis: Risk Factors for Osteonecrosis

Background The incidence of avascular necrosis (AVN) after unstable slipped capital femoral epiphysis (SCFE) varies widely in the literature (10% to 60%), and few studies have examined why certain unstable slips develop osteonecrosis whereas others do not. Our purpose was to determine risk factors for developing AVN after unstable SCFE. Methods We reviewed all unstable SCFEs treated primarily at our center. Medical records were reviewed to determine weight-percentile, age, length of prodromal symptoms, and time to treatment. Operative notes were used to classify treatment as either: (group 1) in situ screw fixation, (group 2) purposeful or inadvertent closed reduction and screw fixation, or (group 3) open reduction and internal fixation, and to determine whether or not the joint was decompressed during surgery. Preoperative radiographs were used to measure slip angle and percent translation. For group 2, these were compared with postoperative radiographs to calculate a &Dgr;slip angle and &Dgr;translation. Student t tests and Fisher exact tests were used for statistical analysis. Results Of the 70 patients in our series, 14 developed AVN (20%). On the basis of treatment, 3 of 16 patients in group 1 (19%), 10 of 38 patients in group 2 (26%), and only 1 of 16 patients in group 3 (6%) developed AVN. Patients who developed osteonecrosis were significantly younger (11.67 y vs. 12.83 y, P=0.04) and had a significantly shorter duration of prodromal symptoms (17.5 d vs. 65.9 d, P=0.03) compared with those who did not develop AVN. None of the other factors were found to be significant. In a subgroup analysis looking solely at group 2 patients, those who developed AVN had a significantly higher initial slip angle compared with those who did not (62 degrees vs. 51 degrees, P=0.03). Conclusions In this, the largest reported series of unstable slips treated with internal fixation, AVN seemed more likely to develop in younger patients with a shorter duration of prodromal symptoms. Patients undergoing open reduction may have a lower incidence of AVN, but our limited power precludes definitive conclusions. Level of Evidence Level IV (case series).

How safe is the operative treatment of Gartland type 2 supracondylar humerus fractures in children

Whereas operative treatment of supracondylar fractures is now standard of care for Gartland type 3 supracondylar humerus fractures in children, the treatment of type 2 fractures remains somewhat controversial. The purpose of this article was to examine the safety and efficacy of closed reduction and pinning of type 2 supracondylar humerus fractures in children. Methods: We performed a retrospective review of 189 type 2 supracondylar humerus fractures operatively treated at one tertiary care childrens hospital from 2000 to 2006. Data were acquired from a review of radiographs and clinical notes. Results: We found no intraoperative surgical or anesthetic complications in our series. None of our cases lost reduction after closed reduction and percutaneous pinning. There were 4 pin tract infections (2.1%) in our series: 3 were treated with antibiotics, and 1 needed irrigation and debridement in the operating room. This was the only patient who required reoperation for any reason. Conclusions: In this study, the largest reported series of type 2 supracondylar humerus fractures in children, we found an extremely low rate of complications after closed reduction and percutaneous pinning; secondary operations were also uncommon (0.5%). Our series demonstrates a high probability of satisfactory outcome after operative treatment of type 2 supracondylar fractures compared with previous studies of children treated by closed reduction without pinning. Level of Evidence: Therapeutic study, level 4 (case series [no or historical control group]).