MATERIALS AND METHODS
After Institutional Review Board approval was obtained, a search was performed on the basis of operative report Current Procedural Terminology (CPT) codes for all patients who underwent PAO performed by a single surgeon between 2005 and 2013. Patients were included if they had PAO surgery with at least 90 days of follow-up. There was no exclusion for age, previous surgery, or underlying hip or medical diagnosis. A retrospective review of electronic medical records and radiographic imaging was undertaken to determine pre- and postoperative demographic information, pain scores, center-edge angle of Weiberg and Tönnis angles, intraoperative estimated blood loss, and all perioperative complications. Weight and height were recorded from the immediate preoperative visit and measured in kilograms (kg) and meters (m), respectively. BMI was derived from these measurements. Pain was assessed via visual analog scale at the preoperative visit as well as at 12 weeks postoperatively. Preoperative and 12-week postoperative Tönnis and center-edge angles were measured by a single orthopedic surgeon. All radiographs were deemed adequate in position and penetration for measurement of these parameters. Evidence of osteonecrosis of the femoral head was evaluated on all postoperative radiographs within this perioperative period. Estimated blood loss was established by review of operative records and anesthesia notes.
Perioperative complications were classified using the Clavien-Dindo system, which has previously been validated for use in hip preservation surgery.30 This includes 5 grades of complications based on the treatment needed and severity of resulting long-term disability. Grade I complications do not require any change in the postoperative course and were therefore left out of our statistical analysis. Examples include symptomatic hardware, mild heterotopic ossification, and iliopsoas tendonitis. Grade II complications are those that require a change in outpatient management, such as delayed wound healing, superficial infection, transient nerve palsy, violation of the posterior column, and intra-articular osteotomy. Grade III complications require invasive or surgical treatment but leave the patient with no long-term disability. Examples include wound dehiscence, hematoma or infection necessitating surgical débridement and irrigation, and revision of the osteotomy due to hardware malposition or hip instability. Grade IV complications involve both surgery and long-term disability. Grade IV complications applicable to hip preservation surgery are osteonecrosis, permanent nerve injury, major vascular injury, or pulmonary embolism. A grade V complication is death.
For analysis and correlation between demographics and perioperative outcomes and complications, patients were grouped into several groups for comparison. Low (<30) vs high (>30) BMI, smokers vs non-smokers, diabetic vs non-diabetic patients, and those who had previous surgery vs those who did not were compared. A two-tailed t test was used for normally distributed continuous variables and a Mann-Whitney U test, for non-parametric data to compare postoperative radiographic correction, pain scores, and complication rates between each of these groups.
The operative technique for PAO as described by Ganz and colleagues5 in 1988 was utilized in all patients. When preoperative imaging showed evidence of labral pathology, a Cam lesion of the femoral head and neck junction, abnormal proximal femoral anatomy, osteonecrosis of the femoral head, or an os acetabulum, a concomitant procedure was performed. Seventeen patients underwent débridement of a Cam lesion noted to be impinging following PAO. Seventeen patients underwent labral débridement and 4 underwent labral repair. Four patients underwent intertrochanteric osteotomy and 1 underwent greater trochanteric slide. Two patients underwent free-vascularized fibular grafting to the ipsilateral femoral head and 5 underwent fixation of an os acetabulum.
Continue to: RESULTS...