Douglas G. Armstrong

Comparison of single and dual growing rod techniques followed through definitive surgery: a preliminary study.

Study Design. Retrospective analysis of patients treated with single and dual growing rods who had completed their course of treatment, had definitive fusion, and had a minimum of 2 years follow-up. Objectives. To determine which technique was the most effective in the management of severe spinal deformity in young children: control of the spinal deformity, spinal growth, and the incidence of complications. Summary of Background Data. Growing rod techniques provide proximal and distal segmental “claw” foundations, but their overall results through definitive fusion have not been clearly determined. Methods. A total of 28 consecutive patients who had growing rod procedures followed through definitive spinal fusions were analyzed. There were three patient groups: Group 1 (N = 5), single submuscular rod and short apical fusion; Group 2 (N = 16), single growing rod alone; and Group 3 (N = 7), dual growing rods. Results. The interval between initial rod insertion and definitive spinal fusion was similar in all three groups. The best overall results occurred in Group 3, whereas the patients in Group 1 had the worse results. Both Groups 2 and 3 provided good initial correction of the spinal deformity and allowed spinal growth. Group 2 had better frontal and sagittal plane balance and the lowest complication rate. Conclusion. The use of growing rods is effective in controlling severe spinal deformities and allowing spinal growth. Dual rods are stronger than single rods and, therefore, provide better initial correction and maintenance of correction. The use of an apical fusion does not appear to be effective over the course of treatment.

Factors affecting forearm compartment pressures in children with supracondylar fractures of the humerus.

This study evaluated forearm compartment pressures in 29 children with supracondylar humerus fractures. Pressures were measured before and after reduction in the dorsal, superficial volar, and deep volar compartments at the proximal 1/6th and proximal 1/3rd forearm. Pressures in the deep volar compartment were significantly elevated compared with pressures in other compartments. There were also significantly higher pressures closer to the elbow within each compartment. Fracture reduction did not have a consistent immediate effect on pressures. The effect of elbow flexion on post-reduction pressures was also evaluated; flexion beyond 90° produced significant pressure elevation. We conclude that forearm pressures after supracondylar fracture are greatest in the deep volar compartment and closer to the fracture site. Pressures greater than 30 mm Hg may exist without clinical evidence of compartment syndrome. To avoid unnecessary elevation of pressures, elbows should not be immobilized in >90° of flexion after these injuries.

Risk Factors for Major Complications After Surgery for Neuromuscular Scoliosis

Study Design. Retrospective, case series. Objective. To determine the prevalence of major complications and to identify factors that increase the risk of complications in patients undergoing surgery for neuromuscular scoliosis. Summary of Background Data. Complications after surgery for neuromuscular scoliosis are more prevalent than in idiopathic scoliosis. However, the associated risk factors have not been statistically significant. Methods. Our computerized Pediatric Orthopedic Spine Database identified 131 consecutive patients with neuromuscular scoliosis, excluding those with myelodysplasia, who underwent surgery and had a minimum of 2 years of follow-up. Preoperative, intraoperative, and postoperative factors were analyzed for any association with major complications and length of stay using stepwise logistic and multiple regression analyses. Odds ratios were calculated for significant dichotomous variables, and receiver operator characteristic curves were created for significant continuous variables. Results. There were 81 male and 50 female patients with a mean age at surgery of 13.4 years (range, 6–21 years). The majority of patients (n = 75) had cerebral palsy. Eighty-eight patients (67%) underwent posterior spinal fusion and segmental spinal instrumentation (only), whereas 43 patients (33%) underwent an anterior spinal fusion followed by a posterior spinal fusion with segmental spinal instrumentation. Seventy-seven patients (59%) were fused to the pelvis using the Galveston technique. The mean follow-up was 3.9 years (range, 2–16.9 years). There were 46 major complications in 37 patients (28% prevalence), including 2 deaths. Nonambulatory status (P < 0.05) and preoperative curve magnitude (P < 0.01) were associated with an increased prevalence of major complications. Nonambulatory patients (n = 94) were almost 4 times more likely to have a major complication (odds ratio of 3.8, P < 0.05) in comparison with ambulatory patients. A preoperative major curve magnitude of ≥60° (P < 0.01) was the most accurate indicator for an increased risk for a major complication. Conclusion. Nonambulatory status and a preoperative curve magnitude (≥60°) are directly associated with an increased risk for major complications and indirectly associated with increased length of stay. As such, we recommend operative intervention in neuromuscular scoliosis before curve progression to ≥60°. Level of Evidence. Level III.

Predicting ulnar nerve location in pinning of supracondylar humerus fractures

Thirty-four consecutive patients with displaced supracondylar humerus fractures were treated with reduction and percutaneous pinning. The precise location of the ulnar nerve to the medial pin was determined by intraoperative nerve stimulation. In 22 of the 34 patients, the authors attempted to predict the location of the ulnar nerve by palpation and placing a mark on the skin. They also recorded the ability to feel the anatomic landmarks for pin fixation, including the medial epicondyle and ulnar nerve. The average distance from the medial pin to the predicted location was 9.3 mm, whereas the actual distance measured 7.6 mm, for a significant difference of 1.7 mm. Statistically, the authors could not accurately predict the location of the ulnar nerve prior to blind percutaneous crossed K-wire fixation of supracondylar humerus fractures. However, clinically they were fairly close in their prediction and documented safe insertion and distance from the nerve. Intraoperative nerve stimulation may assist in localizing the nerve prior to placement of the medial pin. Stimulation of the pin itself following insertion is another technique to ensure safe pin placement and decrease the risk of injury.

Orthopedic management of osteopetrosis : Results of a survey and review of the literature

Osteopetrosis or Albers-Schonberg disease is a rare hereditary disorder of osteoclast function in which resorption of bone is diminished, resulting in abnormally dense bones. The condition is known to occur in at least four recognizable clinical patterns, each of which is variable. The optimal treatment of fractures and of bone deformity in these patients has not previously been made clear. To determine appropriate orthopedic management of the condition, we conducted a survey of the membership of the Pediatric Orthopedic Society of North America. The combined experience of 57 surgeons who treated 79 patients with osteopetrosis was compiled. Four femoral neck fractures treated by closed reduction and internal fixation had a satisfactory result, but three treated nonoperatively developed varus and required osteotomy. A total of 20 hips was treated for coxa vara by various means, none of which was free of complications. Valgus osteotomy, when used as the primary treatment for coxa vara, was the most consistently satisfactory procedure, whereas in situ pinning failed in two of three hips. Fourteen subtrochanteric fractures and 31 other fractures of the femur were treated. Good results were reported with traction or casting or both in the majority of those fractures. Twenty-nine tibia fractures were treated successfully, the majority by nonoperative means. Upper extremity fractures healed well with closed reduction and casting. Vertebral fractures, spondylolysis, and back pain were most frequently treated without surgery.

Wound infections after surgery for neuromuscular scoliosis: risk factors and treatment outcomes.

Study Design. Retrospective, case-control study. Objective. Determine risk factors for postoperative wound infections after surgery for neuromuscular scoliosis as well as the causative organisms and the results of treatment. Summary of Background Data. Wound infection after surgery for neuromuscular scoliosis is more common than that for idiopathic scoliosis. A variety of potential risk factors have been identified, but few have demonstrated statistical significance. Methods. The Pediatric Orthopedic Spine Database identified 151 patients with neuromuscular scoliosis who underwent surgery and had a follow-up of minimum of 2 years. A total of eight patients (5.3% prevalence) developed a postoperative wound infection. Nine patients without an infection were matched by year and type of surgery, for each patient with an infection and selected as controls (n = 72). Preoperative, intraoperative, and postoperative factors were analyzed for an association with wound infection by using stepwise logistic regression. In addition, causative organisms as well as the methods and results of treatment were recorded for each patient. Results. The control group consisted of 32 males and 40 females with a mean age of 13.3 years (range, 7–21 years) and a mean follow-up of 4.6 years (range, 2.0–20.9 years) at surgery. The infection group (n = 8) consisted of four males and four females with a mean age of 12.5 years (range, 11–14 years) and a mean follow-up of 5.1 year (range, 2.0–12.3 years) at surgery. There were five early and three late wound infections. The presence of a ventriculoperitoneal shunt before surgery was the only factor statistically associated with an increased risk for wound infection (P < 0.01). In addition, infection was associated with pseudarthrosis (P < 0.01) and an increased length of hospitalization (P < 0.01). The most common causative species was staphylococcus and the majority (88%) of infections required surgical intervention with a mean of 2.1 debridements (range, 1–4 debridements). Conclusions. The presence of a ventriculoperitoneal shunt is a statistically significant risk factor for wound infection after corrective surgery for neuromuscular scoliosis. Wound infection is associated with pseudarthrosis and prolonged hospitalization. Level of Evidence. III

A randomized prospective study of music therapy for reducing anxiety during cast room procedures.

Background: Cast room procedures, such as cast application and removal, pin removal, and suture removal can cause significant anxiety in young children. The use of music therapy in the cast room to decrease anxiety has not been previously reported. Methods: We performed a randomized, prospective study of soft lullaby music compared with no music in 69 children 10 years or younger undergoing cast room procedures. Heart rates (beats per minute) were recorded in the waiting room and cast room using a pulse oximeter. Results: A total of 28 children were randomized to music and 41 children to no music. The mean rise in heart rate between the waiting room and entering the cast room was −2.7 beats/min in the music group and 4.7 beats/min in the no music group (P = 0.001). The mean difference in heart rate between the waiting room and during the procedure was 15.3 beats/min in the music group and 22.5 beats/min in the no music group (P = 0.05). There were 7 patients in the no music group with heart rate increases of greater than 40 beats/min. No patient in the music group had an increase of this magnitude. Conclusions: Playing soft music in the cast room is a simple and inexpensive option for decreasing anxiety in young children during cast room procedures. Level of Evidence: Randomized Clinical Trial, Level II.

Proximal femoral physis shear in slipped capital femoral epiphysis--a finite element study.

Abstract: The following finite element study was conducted to determine whether increased body weight, femoral retroversion, and varus hip loading could sufficiently raise physeal shear strains and stresses above the yield point and predispose an adolescent hip to a slip. A computer tomography scan of a 13-year-old child with slipped capital femoral epiphysis was used to generate a solid model of the proximal femur and physis. The model was parameterized using 3-dimensional software to generate three difference angles of femoral neck version-neutral, 15° retroversion, and 15° anteversion. Loads of 2.7 times body weight in a 46- and 86-kg child were applied to the proximal femur to model stance on one leg. In addition, the loading vector was reoriented at various degrees of varus to study the effect of varus loading on physis shear. The results demonstrated that physis stress, strain, and displacement increased with greater body weight, retroversion, and varus displacement of the loading vector. Physis shear strain in hips with a combination of varus loading and femoral neck retroversion exceeded the reported ultimate strain values for cartilaginous soft tissues. The finite element models suggest that in an overweight child, the combination of retroversion and varus hip load may be sufficient to increase physeal strains above the yield point and result in a slip.

Role of amicar in surgery for neuromuscular scoliosis

Study Design. A retrospective case-control study. Objective. Evaluate the effectiveness of Amicar in decreasing perioperative blood loss in patients with neuromuscular scoliosis undergoing posterior spinal fusion (PSF) and segmental spinal instrumentation (SSI). Summary of Background Data. Previously, a preliminary prospective; prospective randomized double-blind; same-day anterior and posterior spinal fusion; and fibrinogen studies have demonstrated Amicar to be effective in decreasing total perioperative blood loss and transfusion requirements in surgery for idiopathic scoliosis. Increased fibrinogen secretion is a possible explanation. We are now analyzing its effectiveness in neuromuscular scoliosis. Methods. Amicar was administered at 100 mg/kg over 15 minute not to exceed 5 g after anesthesia induction. Maintenance is 10 mg/kg/h until wound closure. There were 2 study groups: group 1 (n = 34), no Amicar and group 2 (n = 62) who received Amicar. The majority of patients in both groups had cerebral palsy. Total perioperative blood loss was determined from the estimated intraoperative blood loss and measured postoperative suction drainage. Total perioperative blood loss and transfusion requirements (cell saver and allogeneic) were compared using &khgr;2 or Fisher exact test. Results. There was statistically less estimated intraoperative blood loss, total perioperative blood loss, and transfusion requirements in group 2. Postoperative suction drainage was also less but did not reach statistical significance. In group 1, estimated intraoperative blood loss, measured postoperative suction drainage, and total perioperative blood loss were 2194 ± 1626 mL, 903 ± 547 mL, and 3055 ± 1852 mL, whereas in group 2, it was 1125 ± 715 mL, 695 ± 489 mL, and 1805 ± 940 mL. Transfusion requirements were 1548 ± 962 mL in group 1 but only 660 ± 589 mL in group 2 (P < 0.0001). Amicar was equally effective in all diagnoses. There were no complications related to the use of Amicar. Conclusion. Amicar was highly effective in decreasing perioperative blood loss and transfusion requirements in patients with neuromuscular scoliosis undergoing PSF and SSI. It was most effective in decreasing estimated intraoperative blood loss. This results in decreased transfusion requirements, costs, and potential transfusion-related complications.

Comparison of supine bending, push-prone, and traction under general anesthesia radiographs in predicting curve flexibility and postoperative correction in adolescent idiopathic scoliosis.

Study Design. A prospective study comparing supine bending, push-prone, and traction under general anesthesia (UGA) radiographs in adolescent idiopathic scoliosis. Objective. To compare the effectiveness of 3 different flexibility methods on structural and nonstructural main thoracic (MT) and thoracolumbar/lumbar (TL/L) curves. Summary of Background Data. Supine side bending radiographs are the major method for determining curve reducibility. Push-prone radiographs show structural and compensatory curves on the same radiograph, but have not shown comparative reducibility in recent studies. Traction UGA is a relatively new modality which may offer similar or improved flexibility, while also showing structural and compensatory curves on the same radiograph. Methods. Fifty-eight patients with adolescent idiopathic scoliosis were prospectively studied with standing PA and lateral, supine bending and push-prone radiographs before surgery; traction UGA radiographs intraoperatively; and standing PA and lateral radiographs after surgery. Results. Traction UGA demonstrated equal flexibility to supine bending in structural MT and TL/L curves, with a trend towards more flexibility in severe MT curves ≥60°, while push-prone demonstrated significantly less flexibility. Each of the methods showed significantly less flexibility than postoperative correction in MT curves, while traction UGA and supine bending were not significantly different than postoperative correction in TL/L curves. Analysis of nonstructural TL/L curves showed that traction UGA and push-prone were not significantly different than postoperative correction, while supine bending overestimated postoperative correction. Conclusion. Traction UGA offers flexibility equivalent to supine bending for structural MT and TL/L curves, and flexibility comparable with push-prone for nonstructural TL/L curves. Traction UGA also shows both structural and compensatory curves on the same radiograph, and ultimately may provide a better estimate of spinal balance.