After Institutional Research Board Approval, 249 elderly patients (age more than 60 years old) with intertrochanteric fractures from low energy trauma who underwent PFNA fixation from January 2015 until December 2017 were prospectively collected. Demographic data, comorbidity including Charlson Comorbidity Index (CCI), ASA classification (American society of anesthesiologist), Metabolic equivalence (METs), time to union, functional outcome and complications were collected. Hip fracture patients were excluded when they had followed up time of less than one year, they were referred to a different hospital, poly trauma, pathologic fracture, or they had previous history of bisphosphonate intake. There were 196 elderly hip fractures treated with PFNA fixation that met these criteria. Patients were further classified into 2 groups: 75 patients taking bisphosphonate [70 milligrams per oral alendronate once weekly (70.7%, 53 patients), 150 milligrams per oral risedronate once monthly (21.3%, 16 patients), and 150 milligrams per oral ibandronate sodium once monthly (8.0%, 6 patients)] at two weeks after surgical fixation of fracture and those who did not receive bisphosphonate (121 patients). All patients in both groups received supplemental vitamin D and calcium. The primary outcome was measured prospectively by time to clinical union and radiographic union (weeks). The secondary outcome was the functional outcome (Harris Hip Score) and complications including mechanical failure and mortality rate. All outcomes were compared between the two groups.
Data collection and outcome
A total of 196 elderly patients with low energy intertrochanteric fracture underwent PFNA fixation and were included in the study. Patient demographic information, comorbidities, pre-operative and postoperative status, history of prior fracture and treatment, cause of injury, medication at hospital admission and discharge, and radiological reports were also obtained from the medical record review. Patient’s comorbidities were reviewed from the medical record: (1) Diabetes mellitus was grossly classified into two major types (Non-Insulin Dependent Diabetes Mellitus and Insulin Dependent Diabetes Mellitus). (2) Hypertension. (3) Dyslipidemia (4) Lung disease (Pulmonary disease) (5) Heart disease was classified into 5 types (coronary artery disease, valvular heart disease, cardiomyopathy, arrhythmias, and heart infection). (6) Liver disease (7) Kidney disease (8) Dementia.
Additionally, all hip fracture patients had the Charlson Comorbidity Index (CCI) calculated. A single MET is defined to be the resting metabolic rate, or the amount of oxygen consumed while sitting at rest (approximately 3.5 mL O2•kg-1•min-1for a person weighting 70 kg). METs are the ratio of the work metabolic rate to the resting metabolic rate and can be used to quantify an individual’s maximal functional aerobic capacity [11]. METs were stratified as follows: (1) 1-4 (low intensity), and (2) >4 (moderate to high intensity).
All patients received standard medications of calcium and vitamin D supplements. In this study, patients who received any bisphosphonate was classified as the “treated group” and those who did not receive anti-osteoporosis drugs were classified as the “untreated group”. The enrollment of subjects and their allocation of treatment including the outcome was shown in CONSORT diagram.
All patients were prospectively identified for clinical union and radiological union at 2, 4, and 6 weeks, 3, 6, 9, and 12 months consequently. Clinical union was defined by clinical and radiographic measurement: patient can partially bear weight without pain and the radiograph demonstrates incomplete obliteration of the fracture line. Radiographic union was defined by complete obliteration of the fracture line on the radiograph [10]. However, fracture patterns based on modified AO/OTA classification were retrospectively categorized into AO/OTA 31 A1.1, A1.2, A1.3, A2.2, A2.3, A3.1, A3.2, and A3.3. The quality of reduction was measured by neck-shaft angle (degree), displacement between cortices of proximal and distal fragments: gap and step in Anteroposterior (AP) and lateral view (millimeters; mm), and Tip Apex Distance (TAD) (millimeters; mm).
Operative procedure
Fractures were all fixed with a titanium PFNATM nail (Synthes). All patients were operated on the fracture table in supine position. Closed reduction was done under fluoroscopy. After anatomical reduction, a guide wire was inserted into the tip of greater trochanter, proximal reaming was done, diameter of nail was measured under fluoroscopy, and a standard-proximal femoral nail with 200 millimeters length was placed into the medullary canal and the guide wire was removed. Before the application of the helical blade into the femoral head, a guide wire was inserted into the femoral head and the exact position and length of helical blade in AP and lateral views was measured. The helical blade was inserted into the femoral head and it was tightened in the final step.
Postoperative management
Appropriate pain control was provided for all patients, they were allowed weight bearing as tolerated, and deep vein thrombosis prophylaxis was applied during hospital admission.
Outcome measurement
All patients were followed up in clinic at 2 weeks, 4 weeks, 6 weeks, 3 months, 6 months, 9 months, and 1 year. Radiographic measurements were done by two orthopedic training surgeons who did not participate in the operative procedures. Mean of these measurements were calculated. Anteroposterior (AP) and lateral radiographs were assessed by PACS software and were used for assessment of quality of reduction: neck-shaft angle (NSA), displacement between cortices of proximal and distal fragments: gap and step in AP and lateral views (mm), Tip Apex Distance in AP and lateral views (TAD, mm).
Harris Hip score (HHS) is composed of many aspects: Pain (44 points), Limp (11 points), Support (11 points), Distance walked (11 points), Sitting (5 points), Enter public transportation (1 point), Stair (4 points), Put on Shoes and Socks (4 points), Absence of Deformity (4 points), and Range of Motion (5 points). Zero points means the lowest hip score while one hundred points means the maximal hip score. HHS was measured into two aspects in all patients: pre-fracture state by interview and postoperative state at one year follow up by examination in clinic. Surgical complications (mechanical failure including PFNA blade cutout, blade cut through, and varus collapse) and mortality rate were compared between groups.
Statistical analysis
All patient’s information was compared between the treated and untreated groups to identify any differences. Data were summarized using descriptive statistics (mean ± SD and number of patients). Comorbidities were compared using Fisher’s exact test. Age of patient,
Distance between proximal and distal fragment (gap and step in AP and lateral views) (mm), Tip and Apex Distance (TAD) (AP and lateral views, mm), and Neck Shaft Angle (degree) between groups were compared by independent T-test. ASA class, METs, and Fracture pattern (AO/OTA classification 31 A1, 2, and 3) were compared by Chi-Square test while the others were compared by Mann-Whitney U test. P-value less than 0.05 were considered a significant difference.