PAIN Postoperative pain after hip fracture is procedure specific

British Journal of Anaesthesia 2 (1): 111 16 (29) doi:.93/bja/aen345 PAIN Postoperative pain after hip fracture is procedure specific N. B. Foss 12 *, M. T. Kristensen 23, H. Palm 2 and H. Kehlet 4 1 Department of Anesthesiology, 2 Department of Orthopedic Surgery, 3 Department of Physiotherapy and 4 Section of Surgical Pathophysiology 474, Rigshospitalet Copenhagen University, Copenhagen DK-2, Denmark *Corresponding author: Department of Anesthesiology, Rigshospitalet, Copenhagen DK-2, Denmark. E-mail: nbf@comxnet.dk/nicoli.bang.foss@hh.hosp.dk Background. Hip fracture patients experience high pain levels during postoperative rehabilitation. The role of surgical technique on postoperative pain has not been evaluated previously. Methods. One hundred and seventeen hip fracture patients were included in a descriptive prospective study. All patients received continuous epidural analgesia and were treated according to a standardized perioperative rehabilitation programme. Resting pain, pain on hip flexion, and walking were measured during daily physiotherapy sessions on a verbal five-point rating scale during the first four postoperative days. Patients were stratified into four groups according to surgical procedure: screws or pins, arthroplasty, dynamic hip screw (DHS), and intramedullary hip screw (). Results. Cumulated pain levels were significantly different between surgical procedures both for hip flexion (P¼.2) and for walking (P¼.2) with highest dynamic pain levels for patients who had either DHSs or s compared with arthroplasty or parallel implants. There were significant negative correlations between ambulatory capacity assessed by the cumulated ambulation score and both the dynamic cumulated pain scores on hip flexion (r¼2.43, P,.1) and walking (r¼2.36, P¼.4). Conclusions. Postoperative pain levels after surgery for hip fracture are dependent on the surgical procedure, which should be taken into account in future studies of analgesia and rehabilitation. Br J Anaesth 29; 2: 111 16 Keywords: complications, fracture; pain, postoperative Accepted for publication: October 19, 28 Downloaded from http://bja.oxfordjournals.org/ by guest on November 4, 213 Postoperative pain levels after hip fracture are high during ambulation 12 and may worsen outcome after hip fracture. 3 Regional analgesia has been shown to facilitate rehabilitation in orthopaedic procedures, 4 6 epidural analgesia minimizes pain as a restricting factor for physiotherapy after hip fracture surgery, 2 and perioperative regional analgesia has been shown to have the potential to reduce perioperative morbidity in hip fracture patients. 7 8 However, hip fracture patients are a heterogenous group treated surgically with parallel screws, arthroplasty, dynamic hip screws (DHSs) or intra-medullary hip screws (s) according to the fracture type, patient age and prefracture functional level. 9 Previous studies of pain and regional anaesthetic techniques after hip fracture surgery have not examined the influence of surgical procedure on pain levels in the postoperative period. We therefore conducted a descriptive, prospective study of resting and dynamic pain in the postoperative period after hip fracture surgery in patients treated according to a standardized multimodal perioperative care programme, 11 including perioperative continuous epidural analgesia. 2 Methods Patients and design From January 23 to June 26, 981 patients admitted to the Hvidovre University Hospital hip fracture unit were screened for inclusion into this descriptive prospective study. Of these 75 were admitted from other hospital # The Board of Management and Trustees of the British Journal of Anaesthesia 29. All rights reserved. For Permissions, please e-mail: journals.permissions@oxfordjournals.org

Foss et al. wards, 258 were not living in their own home, 129 were not cognitively intact, 25 had other simultaneous fractures, 39 were not capable of independent indoor ambulation, and 12 had a history of substance abuse or were on regular opioid therapy. Of the remaining 443 patients, seven had contraindications to placement of an epidural catheter, 29 could not participate in the physiotherapy programme, and 3 were excluded because they did not receive the standardized pain regimen as a result of inclusion in another study. 2 A total of 26 patients otherwise eligible for inclusion were not included due to unavailability of the investigators, leaving 117 included patients available for analysis. There were no important differences in age, American Society of Anaesthesiologists (ASA) score, functional level, or fracture type between included patients and those eligible for inclusion but not included in the analysis because of unavailability of investigators. The study is a part of Hvidovre University Hospitals Hip Fracture Project, which was evaluated by the Local Ethics Committee, who had no objections to the project and concluded that no written patient consent was necessary. The study was approved by the Danish data protection agency. Procedures On arrival in the emergency room patients received regional analgesia by a fascia iliaca compartment blockade with 4 ml of bupivacaine.25% or mepivacaine 1% both with epinephrine 1:2. 12 After X-ray examination confirmed a hip fracture, the patients were then taken to the postanaesthesia care unit where an epidural catheter was inserted in the L2 3 or L3 4 interspace and tested with 6 mg lidocaine 2% with epinephrine 1:2. Epidural analgesia was provided with a bolus of 25 mg bupivacaine.25% followed by a continuous epidural infusion of bupivacaine.125% and morphine 5 mg ml 21 at a rate of 4 ml h 21 before operation and in the postoperative phase. Anaesthesia for surgery was provided by topping up the epidural with 5 mg of bupivacaine.5% in increments of 5 ml and 1 mg of epidural morphine (2 mg for patients,7 yr). No premedication was given, but slight sedation with propofol was provided at a rate of 4 mg kg 21 min 21 on patient request. Standardized fluid and transfusion therapy were given in the entire perioperative phase. 213 After operation, the patients received bupivacaine.125% and morphine 5 mg ml 21 4mlh 21 continued until 8. a.m. on the fourth postoperative day. All patients received additional analgesia with acetaminophen 1 g 6 hourly and the first 28 patients received rofecoxib 25 mg once daily from the time of admission. This ceased to be or practice when rofecoxib was removed from the market. Rescue medication was provided as morphine bolus intravenously. 2 From admission until the fourth postoperative day, patients received supplemental oxygen therapy 2 litre min 21 when supine. Immediately after surgery, the patients were on regular diet supplemented by three daily protein drinks. The department used the Danish national guidelines for surgical technique for the various fracture types: undisplaced intracapsular fractures were operated on with two parallel implants (Olmed screws or Hansson pins). In displaced intracapsular fractures, the treatment depended on the age of the patient. If the patient was 75 yr or younger, the fracture was reduced and internally fixed with the above mentioned two parallel implants. If the patient was older than 75 yr, an uncemented hemiarthroplasty was inserted. If the hemiarthroplasty was not stable perioperatively, a cemented hemiarthroplasty was inserted. All stable trochanteric and basocervical fractures received a DHS, whereas the unstable trochanteric and subtrochanteric fractures received an. Wound drains were not used. After operation, the patients were mobilized if at all possible on the day of operation, and an intensive physiotherapy programme comprising two daily 3 min sessions, started on the first postoperative day (Day 1). Discharge criteria from the hip fracture unit were standardized: the ability to independently get in and out of bed and to and from a place of eating, the ability to independently perform bathroom visits and the ability to walk with the walking aid to be used in the home. Patients were primarily rehabilitated in the orthopaedic ward and discharged to their home. Study parameters Data were gathered prospectively. ASA classification, type of surgery, length of stay, and 3-day mortality were all registered, the latter established through the Danish civil register. Prefracture functional level expressed by the new mobility score ( 9, with 5 indicative of poor walking function) was recorded upon admission. 14 Mental status, assessed by a validated nine-point Danish version of the abbreviated mental status test was taken upon admission. 15 Physiotherapy sessions were conducted by specially assigned project physiotherapists. The sessions were initiated with an assessment of pain made before the start of physiotherapy after the patient had been resting in bed for 15 min. Dynamic pain was assessed during the treatment sessions on 458 flexion of the hip while supine and upon walking either assisted or independently. Pain was measured as reported by the patient on a five-point verbal ranking score (VRS) from to 4 with the categories none, light, moderate, severe, and intolerable pain. During the physiotherapy session, the patients were evaluated on their ambulatory capacity by the cumulated ambulation score (CAS), 16 which allows day-to-day measurements of functional mobility in hip fracture patients in the early postoperative phase. The CAS ( 18) has been validated and found to be predictive of postoperative rehabilitation outcome. 16 Statistics A composite pain score, representing the cumulated pain score for the first 4 days for each physical function, was 112

Procedures and pain in hip fractures calculated by adding the scores of the individual days. Tests for significant intergroup differences between the four fracture types were made using Kruskall Wallis non-parametric ANOVA, while testing for between group differences where relevant were made with the Mann Whitney test. Correlations were measured by Spearman rank correlation and the x 2 test was used for testing the significance of categorical data. Pain data are presented as median (25 75 percentiles). All data analyses were conducted with SPSS for windows version.1 (SPSS inc., Chicago, IL, USA). Results During the inclusion period, 117 patients qualified for inclusion. Of these, 28 participated in a randomized study comparing epidural and opioid analgesia (only patients receiving standardized epidural analgesia were included). 2 Patient characteristics are shown in Table 1. Included patients had a high prefracture functional and mental status as evidenced by the new mobility and mental scores. This was reflected in a 3-day mortality of only 2%. There were no important differences in characteristics between patients according to surgical procedure. Pain scores at rest and during physiotherapy stratified by the type of surgical procedure are presented in Table 2. Pain scores at rest were low, with patients almost uniformly reporting no pain at rest and no significant differences between the different types of surgery. Dynamic pain scores showed a consistent trend on all four postoperative days, with patients with arthroplasty reporting the lowest pain levels and patients with DHS and reporting higher scores highest for. These differences reached statistical significance for hip flexion on Days 2 and 4 (P¼.2) and on Day 1 for walking (P¼.2). The cumulated pain scores for the first 4 days are presented in Figure 1. There were significant differences between the four types on surgery for both hip flexion (P¼.2) and walking (P¼.2) pain scores. The patients with arthroplasty procedures had the lowest dynamic pain levels with DHS and procedures having significantly higher pain levels on hip flexion and hip flexion plus walking, respectively. The percentage of patients reporting either slight pain or higher (VRS 1 4) at rest or moderate pain or higher (VRS 2 4) on either hip flexion or walking is presented in Figure 2. Significant negative correlations were found between the CAS and both the dynamic cumulated pain score pain on hip flexion (r¼2.43, P,.1) and the cumulated pain score on walking (r¼2.36, P¼.4); there was no significant correlation between cumulated pain at rest and the CAS. Discussion Pain after hip fracture surgery according to procedure type has not previously been studied in detail. We found significant differences in dynamic pain between procedures, with hip arthroplasty and parallel implants having the lowest pain levels and DHS and the highest. We also found a significant inverse correlation between dynamic pain and ambulation scores during the first four postoperative days. Previous studies have documented high pain levels after hip fracture surgery with conventional analgesic methods. 1 Postoperative epidural analgesia with local anaesthetics and low-dose opioids has been documented to reduce postoperative myocardial ischaemia, 8 improve analgesia and minimize pain as a limiting factor for postoperative rehabilitation. 2 Limitations in postoperative rehabilitation because of motor block have not been demonstrated. 2 The risk/ benefit ratio of regional analgesic methods is theoretically dependent on the postoperative pain level of the surgical procedure, since patients with low levels of postoperative pain will potentially be more hampered by indwelling catheters, delivery systems and any residual motor or urinary bladder blockade compared with their potential gains in ambulation due to attenuation of dynamic pain, whereas the opposite seems to be the case with patients with moderate to high levels of dynamic pain. As such, optimal postoperative pain therapy should therefore be procedure specific to minimize unwanted side effects. 17 Procedures with parallel pins or screws are in principle minimally invasive, with small amounts of tissue trauma and low blood loss leaving the intracapsulary fractured bone in situ; arthroplasty has a larger incision and amount of tissue trauma but essentially removes the fracture site; whereas DHS and procedures have moderate to Table 1 Characteristics of hip fracture patients in the study of pain and type of surgery. : DHS, dynamic hip screw;, intramedullar hip screw; ASA, American Society of Anaesthesiologists classification. Data are presented as median (range) for numeric data Screws/pins Arthroplasty DHS Number of patients 9 44 49 15 Age 8 (67 91) 82 (73 94) 81 (41 98) 81 (69 97) Female sex 8 (9%) 4 (91%) 32 (65%) 12 (8%) ASA III IV 3 (33%) 13 (3%) 13 (27%) 4 (27%) New mobility score ( 9) 6 (3 9) 8 (3 9) 9 (2 9) 7 (2 9) Mental score ( 9) 9 (6 9) 9 (5 9) 9 (6 9) 9 (6 9) Delay to surgery (h) 2 ( 36) 19 (3 54) 19 (5 47) 21 (8 47) Intraoperative bleeding (ml) (2 15) 275 (5 14) 2 ( 14) 3 ( 7) Hospitalization (days) 11 (6 22) 13 (6 8) 14 (4 7) 16 ( 52) 3-day mortality 1 (2%) 1 (2%) 113

Foss et al. Table 2 Pain at rest and during mobilization in 117 hip fracture patients according to type of surgery. Pain score is a verbal ranking score (VRS) 4. Values given are median (25 75 percentiles). Test for significant differences between groups with Kruskall Wallis non-parametric ANOVA Number of patients Cumulated VRS (Days 1 4) 12 8 6 4 2 Screws/pins Screws/pins Arthroplasty DHS P-value 9 44 49 15 Pain at rest Day 1 ( ) ( ) ( ) ( ).3 Day 2 ( ) ( ) ( ) ( ).82 Day 3 ( ) ( ) ( ) ( ).89 Day 4 ( ) ( ) ( ) ( ).42 Pain on 458 hip flexion Day 1 1 ( 2) 1 ( 1) 1 ( 2) 1 (1 2).8 Day 2 1 ( 2) ( 1) 1 ( 2) 1 (1 3).2 Day 3 1 ( 1) ( 1) 1 ( 2) 1 ( 1).39 Day 4 ( 1) ( 1) 1 ( 2) 1 ( 2).2 Pain on walking Day 1 2 ( 2) 1 ( 2) 1 (1 2) 2 (2 2).2 Day 2 1 ( 2) 1 ( 1) 1 ( 2) 2 (1 2).2 Day 3 1 (1 1) 1 ( 1) 1 (1 2) 1 (1 3).35 Day 4 1 (1 2) 1 ( 2) 1 (1 2) 1 (1 2).65 Cumulated ambulation score ( 18) (6 17) 9 (6 13) 9 (9 12) 9 (8 9).36 Cumulated pain Arthroplasty DHS Rest P=.21 Hip flexion P=.2 Walking P=.2 Fig 1 Cumulated pain score for the first four postoperative days in 117 hip fracture patients according to type of surgery. *Indicates values significantly different (P,.5) from the pain values for the same activity in the arthroplasty group. VRS, verbal ranking score. high levels of tissue trauma and leave the fractured bone in situ. 13 Correspondingly, patients with elective hip joint surgery with arthroplasty has previously been shown to have moderate initial pain levels that quickly taper off 24 h postsurgery, 18 which is in contrast to data on dynamic pain after hip fracture surgery in a mixed cohort of procedures. 2 This suggests that pain levels after surgery for hip fracture are heterogeneous and procedure specific. The present study applied a standardized pain regimen within a standardized perioperative care pathway 11 and as such minimized confounding factors. However, the study is limited in its size, and the distribution of procedures within the group is skewed mirroring the daily clinical * * * Percentage with VRS 1 4 Percentage with VRS 2 4 Percentage with VRS 2 4 9 8 7 6 5 4 3 2 9 8 7 6 5 4 3 2 9 8 7 6 5 4 3 2 Screws/pins Screws/pins Arthroplasty Pain at rest DHS Pain on hip flexion Arthroplasty DHS Pain on walking Screws/pins Arthroplasty DHS Day 1 Day 2 Day 3 Day 4 Day 1 Day 2 Day 3 Day 4 Day 1 Day 2 Day 3 Day 4 Fig 2 Percentage of 117 hip fracture patients reporting any pain at rest, or moderate or higher dynamic pain in hip flexion and walking during physiotherapy. pattern of procedure types in hip fracture patients. Thus, the pain data for pins/screws and are less robust than that for the most common procedures, DHS and arthroplasty. The patients that were included in this study represent the fittest members of the hip fracture population, although there is no evidence to suggest that more fragile patients should have a different distribution of pain according to procedure type. 114

Procedures and pain in hip fractures Our data showed very low levels of postoperative resting pain irrespective of procedure, probably due to the effective epidural regimen which provides superior pain relief at rest compared with conventional opioid analgesia, which also accounts for the very low levels of supplemental opioid analgesia administered under the regimen. 2 Dynamic pain levels were significantly different between groups when cumulated over the entire period both for hip flexion and walking. Pain levels were also consistent during all four postoperative days. Pain on walking was moderate or higher in 5% of patients with DHS during all 4 days and in 8% of patients with on the first day. Therefore, a large portion of these patients actually had inadequate pain therapy during physiotherapy, despite receiving epidural analgesia. Male sex was more frequent in patients receiving a DHS procedure, but in previous studies of postoperative pain, pain levels have not been sex-dependent in elderly patients (only one patient in the DHS group was less than 65 yr of age). 19 Previous studies have found pertrochanteric fractures to be associated with reduced postoperative rehabilitation outcomes, 16 which may be explained by increased postoperative pain levels as these fractures usually, have a DHS procedure. 2 We found a significant inverse association between the cumulated dynamic pain scores and ambulation scores supporting the assumption that inadequate pain therapy has a negative impact on rehabilitation. 23 Although the correlation was significant, it was not very strong, probably due to the heterogeneity of the population, with many other factors such as preoperative ambulatory capacity determining postoperative rehabilitation. In order to reinforce the signal and simplify data analysis, a cumulated pain score was used. Since pain scores are ordinal by nature this is similar to constructing a composite score, a method used in many pain studies. 21 24 The present study has important implications for future studies of perioperative care in hip fractures. Thus, studies of regional analgesic techniques, both neuraxial and peripheral, may have different benefits vs side effects in the different surgical procedures as the relationship between pain relief facilitating ambulation and motor and urinary bladder blockade will be procedure specific. In addition, the optimal duration of regional analgesia could be procedure specific. In summary, we found dynamic pain after hip fracture surgery to be procedure specific and highest in patients receiving DHS or procedures. Consequently, in future studies of postoperative pain therapy and rehabilitaion after hip fracture surgery, patients should be stratified according to surgical technique and fracture type. Acknowledgements This paper should be attributed to Departments of Anesthesiology, Orthopedic Surgery, and Physiotherapy, Hvidovre University Hospital, Copenhagen DK-265, Denmark. Funding This work received financial support from IMK Almene Fond, Copenhagen, Denmark. References 1 Morrison RS, Siu AL. A comparison of pain and its treatment in advanced dementia and cognitively intact patients with hip fracture. J Pain Symptom Manage 2; 19: 24 8 2 Foss NB, Kristensen MT, Kristensen BB, Jensen PS, Kehlet H. Effect of postoperative epidural analgesia on rehabilitation and pain after hip fracture surgery: a randomized, double-blind, placebo-controlled trial. Anesthesiology 25; 2: 1197 24 3 Morrison RS, Magaziner J, McLaughlin MA, et al. The impact of post-operative pain on outcomes following hip fracture. 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