Postoperative Complications After Hip Surgery in Patients With Cerebral Palsy: A Retrospective Matched Cohort Study Rachel DiFazio, PhD, RN, PPCNP-BC, FAAN,* Judith A. Vessey, PhD, MBA, RN, FAAN,w Patricia Miller, MS,* Kelsey Van Nostrand, BS,w and Brian Snyder, MD, PhDz

Background: Little is known about the postoperative complications experienced by patients with severe cerebral palsy (CP) (GMFCS IV-V) compared with otherwise healthy patients with hip pathology requiring surgery. The purpose of this study was to determine whether differences exist between these 2 groups with respect to the incidence, type, and severity of complications. In addition, we evaluated the risk factors for complications and the number and cost of additional visits, hospital admissions, and repeat surgeries due to complications. Methods: Retrospective matched cohort study of 55 patients aged 3 to 25 years with severe CP and 55 non-CP patients with hip dysplasia who underwent hip osteotomies (2000 to 2012). Postoperative complications were evaluated using the adapted Clavien-Dindo classification system. Binary and ordinal logistic regressions were used to identify risk factors for complications. The number and cost of unplanned visits, admissions, and surgeries were calculated. Results: CP patients experienced almost twice as many complications as the non-CP patients (P = 0.004). All types of complications occurred in both groups except orthopaedic complications (P < 0.001) were more frequent in the non-CP group. CP patients were 82% more likely to develop a complication compared with non-CP patients (relative risk = 1.82; 95% confidence interval = 1.21 to 2.76). The severity of complications was comparable with no significant differences in the relative distribution between the groups. There was a significant difference between groups for the number of unplanned clinic and emergency department visits (Pr0.001). The average cost for treating a complication was $1857.00 for CP and $1800.00 for non-CP (P = 0.72). Conclusions: Although patients with severe CP requiring hip surgery have a 65% chance of experiencing at least 1 postoperative complication compared with 36% of non-CP patients, most of the complications were medical in the CP patients (n = 46, 83%) as opposed to the non-CP patient who experienced predominantly orthopaedic complications (59%). When From the *Orthopedic Center, Boston Children’s Hospital; zBoston Children’s Hospital, Boston; and wWilliam F. Connell School of Nursing, Boston College, Chestnut Hill, MA. The authors declare no conflicts of interest. Reprints: Rachel DiFazio, PhD, RN, PPCNP-BC, FAAN, Orthopedic Center, Boston Children’s Hospital, 300 Longwood Avenue, Boston, 02115, MA. E-mail: [email protected] Copyright r 2015 Wolters Kluwer Health, Inc. All rights reserved.

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these complications occur the associated costs are greater for CP patients as a whole, but are relatively similar per patient. Level of Evidence: Level III—Prognostic, case-control study. Key Words: cerebral palsy, postoperative complications, femoral osteotomies, pelvic osteotomies (J Pediatr Orthop 2016;36:56–62)


reventing surgical complications is critically important to providing quality care and containing costs.1 With the advent of accountable care organizations, orthopaedic surgery programs must better understand the frequency, type, and associated costs of complications associated with common orthopaedic procedures performed in their most complex patients if complications are to be minimized. Children with severe cerebral palsy (CP) are one such group.2 CP is a chronic neurodevelopmental condition that begins in childhood and persists throughout life. Its prevalence is1.5 to more than 4 per 1000 live births.3–7 CP is characterized by a group of motor disorders, often accompanied by disturbances of sensation, perception, cognition, communication, and behavior.8 The Gross Motor Function Classification System (GMFCS) is a 5-level rating scale used to classify functional abilities.9,10 The most severely involved children are classified as GMFCS level IV-V. These children have limited voluntary control of movement, unable to sit, stand, or walk independently and are dependent on caretakers for all activities of daily living.10 The incidence of hip dislocation/subluxation is related to CP severity, affecting approximately 45 to 90% of patients with GMFCS IV-V CP.11–14 Surgical hip reconstruction is recommended for children over the age of 4 who have Z60% lateral migration of the hip on x-ray with the goal of preventing subsequent degenerative changes, coxa arthrosis, and pain.15 Despite the frequency of hip surgery in this population, little is known about the associated postoperative complications. The purpose of this study was to compare patients with severe CP (GMFCS IV-V) to matched nonCP patients with hip pathology requiring femoral and/or pelvic osteotomies to determine differences in incidence, type, and severity of complications, and to identify specific J Pediatr Orthop

Volume 36, Number 1, January 2016

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J Pediatr Orthop

Volume 36, Number 1, January 2016

risk factors for both groups. The number and costs of unplanned clinic visits, emergency department (ED) visits, hospital admissions, and additional surgeries for treating identified complications were calculated.

Postoperative Complications After Hip Surgery

TABLE 1. Adapted Clavien-Dindo Complication Classification System Grade I

METHODS Design and Setting This retrospective matched cohort study was approved by the hospital’s Institutional Review Board. A power analysis indicated that a total sample of 110 patients, 55 patients per group, would provide 80% power to detect a clinically significant 20% difference in the complication rate between groups using a 2-sided w2 test (a = 0.05). All patients were treated at the same tertiary care children’s hospital by fellowship-trained pediatric orthopaedic surgeons experienced in treating complex hip pathology.

Patient Selection Severely involved CP patients who underwent femoral and/or pelvic osteotomies were identified using an orthopaedic database and the International Statistical Classification of Disease, Ninth Revision (ICD-9), Clinical Modification charge codes. The inclusion criteria for patient selection included: (1) age 3 to 25 years at surgery, (2) GMFCS IV-V, and (3) had at least 1-year follow-up data. Subjects’ records were matched on a 1:1 basis to non-CP patients based on the type of surgery performed. Patients were not matched on whether they underwent unilateral or bilateral surgery as CP patients routinely undergo bilateral procedures, whereas non-CP patients undergo unilateral procedures. Match criteria included: equivalent surgical procedures, age at surgery, and sex. These otherwise healthy patients were diagnosed with developmental dysplasia of the hip, Legg-Calves-Perthes Disease, excessive femoral anteversion, or developmental coxa vara.






Specific Complications

A complication that requires A symptomatic grade I or II no treatment and has no heterotopic ossification; clinical relevance; there is no postoperative fever, nausea, deviation from routine constipation, minor urinary follow-up during the tract infections; wound postoperative period; problem not requiring a allowed therapeutic regimens change in postoperative care include: antiemetics, antipyretics, analgesics, diuretics, electrolytes, antibiotics, and physiotherapy A deviation from the normal Superficial wound infection postoperative course (additional clinic visit); (including unplanned clinic transient neurapraxia from visits) that requires positioning or surgical outpatient treatment: either retraction that resolves under pharmacologic or close close observation (complete monitoring as an outpatient resolution); trochanteric delayed union A complication that is treatable Trochanteric nonunion; but requires surgical, fracture; deep infection; endoscopic, or radiographic surgical hematoma; clinically interventions or an significant heterotopic unplanned hospital ossification that requires admission surgical excision; deep vein thrombosis (admission and anticoagulation) A complication that is life Osteonecrosis; permanent threatening, requires nerve injury; major vascular admission to intensive care injury; pulmonary embolism; unit, or is not treatable with central nervous system potential for permanent complications; organ disability; a complication dysfunction that requires organ resection (THA) Death Published with permission from Sink et al.17

study, a pair of raters independently reviewed and graded each complication.

Measurements A standardized data extraction form was used to capture demographic information. Complications were defined as any deviation from the normal postoperative course that occurred from time of surgery until 1 year postoperatively. Complications were grouped into 8 categories. The numbers of unplanned clinic and ED visits, medical admissions, and repeat surgeries related to complications were noted. Direct costs to the hospital, excluding overhead costs and professional fees, were obtained from the billing department. The Clavien-Dindo Classification of Surgical Complications modified by Sink and colleagues for use in orthopaedics16,17 was used. Complications were ranked from grades I to V according to their need for treatment (Table 1). The adapted classification system was validated in patients who underwent hip preservation surgery and found to have high interobserver (Fleiss k = 0.887) and intraobserver (Cohen k = 0.891) reliabilities.17 In our Copyright


2015 Wolters Kluwer Health, Inc. All rights reserved.

Statistical Analysis Descriptive statistics were used to describe and compare the demographic characteristics. The complication rate was defined as the number of patients who experienced at least 1 complication out of the total number of patients per group. The complication rate was estimated and compared across groups using a w2 test. The relative and attributable risks were estimated along with the 95% confidence intervals (CIs). The complication severity was compared using the Cochran-Armitage trend test. Binary regression was used to identify predictors of developing at least 1 complication. Potential predictors included diagnosis, age, sex, percentile body mass index (BMI), surgical procedure, revision surgery, length of surgery, length of hospital stay, presence of pre-existing medical conditions, and postoperative immobilization. Predictors of complication severity were identified using ordinal logistic regression. Based on the univariate analysis, www.pedorthopaedics.com |

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J Pediatr Orthop

DiFazio et al

only variables with a significance of 0.20 or lower were included in the multivariable model. Independent 2-sided ttests were used to compare log-transformed cost data; the significance level was set at

Postoperative Complications After Hip Surgery in Patients With Cerebral Palsy: A Retrospective Matched Cohort Study.

Little is known about the postoperative complications experienced by patients with severe cerebral palsy (CP) (GMFCS IV-V) compared with otherwise hea...
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