Regional anaesthesia is integral to best practice analgesia for patients with neck of femur fractures (NOFFs). These patients are generally frail and are vulnerable to side effects of opioid analgesia. Femoral nerve block (FNB) or fascia-iliaca block (FIB) can reduce opioid requirement. Literature supports good efficacy for extra-capsular NOFFs however it is acknowledged to be suboptimal for intracapsular fractures. We present a novel technique, using point of care ultrasound guidance to perform hip ultrasound guided haematoma (HUSH) aspiration, and injection of local anaesthetic (block) for intracapsular NOFFs. This a case control series. A consecutive series of cognitively intact patients, with an isolated intra-capsular NOFF, received a HUSH block using 10mls of 0.75% Ropivicaine. Haematoma was aspirated and volume recorded. This was performed in addition to standard NOFF pathway analgesia that includes a FIB and multimodal analgesia including opioids. Visual Analogue Scale (VAS)pain scores at rest and on movement were recorded pre and post procedure as well as combined morphine equivalent units administered post HUSH block. The control arm was a retrospective group of similar patients who followed the routine care pathway including a FIB. VAS pain scores from observation charts and usage of morphine equivalent units were calculated. Ten patients consented to receive HUSH blocks and we included thirty-eight patients in our control series. The HUSH block group showed mean VAS pain score of 4.2/10 at rest and 8.6 on movement prior to block. In the time after the block, VAS pain scores reduced to 1.5 at rest (p=0.007) and 3.1 on movement (p=0.0001) with a mean total morphine equivalent use of 8.75mg. This is significantly different from the control group's mean VAS pain at rest score 6.9 (p=0.0001) and 24.1mg total morphine equivalent (p=0.07). HUSH Block in addition to fascia iliaca block appears to significantly better pain relief in intracapsular neck of femur fracture patients when compared to fascia iliaca block alone. We believe it is relatively easy to perform with readily available ultrasound scanners in emergency departments

Aims

Single-shot adductor canal block (ACB) after total knee arthroplasty (TKA) for postoperative analgesia is a common modality. Patients can experience breakthrough pain when the effect of ACB wears off. Local anaesthetic infusion through an intra-articular catheter (IAC) can help manage breakthrough pain after TKA. We hypothesized that combined ACB with ropivacaine infusion through IAC is associated with better pain relief compared to ACB used alone.

Aims

Manipulation under anaesthesia (MUA) remains an effective intervention to address restricted range of motion (ROM) after total knee arthroplasty (TKA) and occurs in 2% to 3% of primary TKAs at our institution. Since there are few data on the outcomes of MUA with different anaesthetic methods, we sought to compare the outcomes of patients undergoing MUA with intravenous (IV) sedation and neuraxial anaesthesia.

Aims

Liposomal bupivacaine (LB) as part of a periarticular injection protocol continues to be a highly debated topic in total knee arthroplasty (TKA). We evaluated the effect of discontinuing the use of LB in a periarticular protocol on immediate postoperative pain scores, opioid consumption, and objective functional outcomes.

We performed a randomized feasibility trial to examine the impact of preoperative femoral nerve block (FNB) on elderly patients with hip fractures, including those with mild to moderate cognitive impairment. We evaluated the impact of preoperative FNB on the following outcomes within 5 days of surgical fixation: 1. Pain levels, 2. Total narcotic consumption, 3. Postoperative mobilization. Randomized allocation of 73 patients in a 2:1 intervention:control ratio. To allow comparison between the 2 groups as well as sub- analysis of the intervention group to examine treatment fidelity (i.e. the ability to deliver the intervention as planned). Inclusion criteria: Patient age≥ 65 years admitted with a low energy hip fracture, ambulatory preinjury, Mini Mental State Exam MMSE score≥13 (moderate dementia), Able to provide direct or proxy consent. Exclusion criteria: Admission ≥ 30 hours after injury, prior regular use of opiates. Potential participants were identified and either participants or proxy respondents provided signed informed consent. Participants allocated to the intervention group received a FNB administered by the UAH acute pain service (APS) within 20 hours of admission to hospital in addition to the usual care. Participants in the control group received usual care. Participants were followed for 5 days postoperatively with daily assessment of pain, narcotic consumption, delirium and mobility. Main outcome measure: (1) Pain at rest and activity (2) Preoperative and postoperative opioid consumption, (3) Mobilization in POD#1. Overall, 73 participants were enrolled (23 Control: 50 FNB). The FNB group was slightly older (mean [SD] 80.1 [8.7] vs. 76.2 [9.2], p=0.09) and had more males (21 [42%] vs. 5 [22%], p=0.09) than the Control group. The mean MMSE score for both groups was >24 (p=0.35 for group comparison), suggesting minimal cognitive impairment of participants. The FNB group reported significantly less pain at rest and activity than the control group over time (p < 0 .001 for both). Opioid consumption were non-significantly higher and more variable in the control group preoperatively (Median [25, 75 quartile] 10.6 [0, 398] vs 7.5 [0, 125], p=0.26) and postoperatively (13.1 [0, 950] vs 10 [0, 260], p=0.31). 41 (85%) of FNB participants mobilized on day 1 vs. 16 (73%) of control participants (p=0.21). Preoperative FNB significantly reduced pain. Opioid consumption was not significantly different, but more variable in the control group. Although not significant, more FNB patients successfully mobilized on day 1 postoperatively. Participants with cognitive impairment were not enrolled due to difficulty in obtaining proxy consent. A definitive randomized trial would be feasible and add valuable information about pain management following hip fracture

Dexmedetomidine, an alpha 2 agonist, has been approved for providing sedation in the intensive care unit. Along with sedative properties, it has analgesic activity through its highly selective action on alpha 2 receptors. Recent studies have examined the use of dexmedetomidine as an adjuvant to prolong the duration of peripheral nerve blocks. Studies showing effectiveness of dexmedetomidine for adductor canal block in knee surgery are small. Also, its effectiveness has not been compared to Epinephrine which is a strong alpha and beta receptor agonist. In a previous study, we showed that motor sparing knee blocks significantly increased the duration of analgesia compared with periarticular knee infiltration using local anesthetic mixture containing Epinephrine following total knee arthroplasty (TKA). In this study, we compared two local anesthetic mixtures: one containing Dexmedetomidine and the other Epinephrine for prolongation of motor sparing knee block in primary TKA patients. After local ethics board approval and gaining Notice of Compliance (NOC) from Health Canada for use of Dexmedetomidine perineurally, 70 patients between the ages 18 – 95 of ASA class I to III undergoing unilateral primary total knee arthroplasty were enrolled. Motor sparing knee block − 1) Adductor canal continuous catheter 2) Single shot Lateral Femoral Cutaneous Nerve block 3) Single shot posterior knee infiltration was performed in all patients using 60 ml mixture of 0.5% Ropivacaine, 10 mg Morphine, 30 mg Ketorolac. Patients randomized into the Dexmedetomidine group (D) received, in addition to the mixture, 1mcg/kg Dexmedetomidine and the Epinephrine (E) group received 200mcg in the mixture. The primary outcome was time to first rescue analgesia as a surrogate for duration of analgesia and secondary outcomes were NRS pain scores up to 24 hours and opioid consumption. The time to first rescue analgesia was not significantly different between Epinephrine and dexmedetomidine groups, Mean and SD 18.45 ± 12.98 hours vs 16.63 ± 11.80 hours with a mean difference of 1.82 hours (95% CI −4.54 to 8.18 hours) and p value of 0.57. Pain scores at 4, 6, 12, 18 and 24 hours were comparable between groups. Mean NRS pain scores Epinephrine vs Dexmedetomidine groups were 1.03 vs 0.80 at 4 hours, 1.48 vs 3.03 at 6 hours, 3.97 vs 4.93 at 12 hours, 5.31 vs 6.18 and 6.59 v 6.12 at 24 hours. Opioid consumption was also not statistically significant between both groups at 6, 12 18, 24 hours (p values 0.18, 0.88, 0.09, 0.64 respectively). Dexmedetomidine does not prolong the duration of knee motor sparing blocks when compared to Epinephrine for total knee arthroplasty. Pain scores and opioid consumption was also comparable in both groups. Further studies using higher dose of dexmedetomidine are warranted

Aims. Adductor canal block (ACB) has emerged as an alternative to femoral nerve block (FNB) for analgesia after total knee arthroplasty (TKA). The optimal duration of maintenance of the ACB is still questionable. The purpose of this study was to compare the analgesic benefits and physiotherapy (PT) outcomes of single-shot ACB to two different regimens of infusion of the continuous ACB, 24-hour and 48-hour infusion. Patients and Methods. This was a prospective, randomized, unblinded study. A total of 159 American Society of Anesthesiologists (ASA) physical status I to III patients scheduled for primary TKA were randomized to one of three study groups. Three patients did not complete the study, leaving 156 patients for final analysis. Group A (n = 53) was the single-shot group (16 female patients and 37 male patients with a mean age of 63.9 years (. sd. 9.6)), group B (n = 51) was the 24-hour infusion group (22 female patients and 29 male patients with a mean age of 66.5 years (. sd. 8.5)), and group C (n = 52) was the 48-hour infusion group (18 female patients and 34 male patients with a mean age of 62.2 years (. sd. 8.7)). Pain scores, opioid requirements, PT test results, and patient-reported outcome instruments were compared between the three groups. Results. The proportion of patients reporting severe pain, defined as a pain score of between 7 and 10, on postoperative day number 2 (POD 2) were 21% for the single-shot group, 14% for the 24-hour block group, and 12% for the 48-hour block group (p = 0.05). Cumulative opioid requirements after 48 hours were similar between the groups. Functional outcomes were similar in all three groups in POD 1 and POD 2. Conclusion. There was no clear benefit of the 24-hour or 48-hour infusions over the single-shot ACB for the primary endpoint of the study. Otherwise, there were marginal benefits for keeping the indwelling catheter for 48 hours in terms of reducing the number of patients with moderate pain and improving the quality of pain management. However, all three groups had similar opioid usage, length of hospital stay, and functional outcomes. Further studies with larger sample sizes are needed to confirm these findings. Cite this article: Bone Joint J 2019;101-B:340–347

Aims

Cementless primary total hip arthroplasty (THA) is associated with risks of bleeding and thromboembolism. Anticoagulants are effective as venous thromboprophylaxis, but with an increased risk of bleeding. Tranexamic acid (TXA) is an efficient antifibrinolytic agent, but the mode and timing of its administration remain controversial. This study aimed to determine whether two intravenous (IV) TXA regimens (a three-hour two-dose (short-TXA) and 11-hour four-dose (long-TXA)) were more effective than placebo in reducing perioperative real blood loss (RBL, between baseline and day 3 postoperatively) in patients undergoing THA who receive rivaroxaban as thromboprophylaxis. The secondary aim was to assess the non-inferiority of the reduction of blood loss of the short protocol versus the long protocol.

Background. The Arthroplasty Pain Experience (APEX) studies are two randomised controlled trials in primary total hip (THR) and knee replacement (TKR) at a large UK orthopaedics centre. APEX investigated the effect of local anaesthetic wound infiltration (LAI), administered before wound closure, in addition to standard analgesia, on pain severity at 12 months. This abstract reports results of the within-trial economic evaluations. Methods. Cost-effectiveness was assessed from the health and social care payer perspective in relation to quality adjusted life years (QALYs). Resource use was collected from hospital records and patient-completed postal questionnaires, and valued using unit cost estimates from local NHS Trust and national tariffs. Missing data were imputed using chained equations. Costs and outcomes were compared per trial arm and plotted in cost-effectiveness planes. The economic results were bootstrapped incremental net monetary benefit statistics (INMB) and cost-effectiveness acceptability curves. One-way deterministic sensitivity analyses explored any methodological uncertainty. Results. In both trials, LAI was cost-saving and more effective than standard care. Using the £20,000 per QALY threshold, in THR, the INMB was £1,125 (95%BCI, £183 to £2,067) and the probability of being cost-effective was over 98%. In TKR, the INMB was £264 (95%BCI, −£710 to £1,238), with only 62% probability of being cost-effective. Considering an NHS perspective only, LAI was no longer dominant in THR, but still highly cost-effective, with an INMB of £961 (95%BCI, £50 to £1,873). Conclusions. Administering LAI is a cost-effective treatment option in THR and TKR surgeries. The evidence is stronger for THR, because of larger QALY gain. In TKR, there is more uncertainty around the economic result, and smaller QALY gains, but results point to LAI being cheaper than standard analgesia, which includes a femoral nerve block. Trial Registration. ISRCTN96095682, 29/04/2010. Funding. NIHR Programme Grant for Applied Research RP-PG-0407-10070

Aims. The aim of this study was to determine the optimal regimen for the management of pain following total knee arthroplasty (TKA) by comparing the outcomes and cost-effectiveness of different protocols implemented at a large, urban, academic medical centre. Patients and Methods. Between September 2013 and September 2015, we used a series of modifications to our standard regimen for the management of pain after TKA. In May 2014, there was a department-wide transition from protocols focused on femoral nerve blocks (FNB) to periarticular injections of liposomal bupivacaine. In February 2015, patient-controlled analgesia (PCA) was removed from the protocol while continuing liposomal bupivacaine injections. Quality measures and hospital costs were compared between the three protocols. Results. The cohort being treated with PCA-less liposomal bupivacaine injections had a significantly higher percentage of patients who were discharged to their home (p = 0.010) and a significantly shorter length of stay (p < 0.001). Patient-reported Hospital Consumer Assessment of Healthcare Providers and Systems (HCAHPS) scores relating to pain being “well-controlled” and “overall pain management” also favoured this cohort (p = 0.214 and p = 0.463, respectively), in which cost was significantly lower compared with the other two cohorts (p = 0.005). Conclusion. The replacement of FNBs injections and the removal of PCAs, both of which are known to be associated with high rates of adverse outcomes, and the addition of liposomal bupivacaine periarticular injections to a multimodal pain regimen, led to improvements in many quality measures, HCAHPS pain scores, and cost-effectiveness. Cite this article: Bone Joint J 2018;100-B(1 Supple A):55–61

Wall PDH, Parsons NR, Parsons H, Achten J, Balasubramanian S, Thompson P, Costa ML; P. D. H. Wall on behalf of A. P. Sprowson,† M. L. Costa, PAKA Study Group. A pragmatic randomised controlled trial comparing the efficacy of a femoral nerve block and periarticular infiltration for early pain relief following total knee arthroplasty. Bone Joint J 2017;99-B:904-911

Aims. The aim of this study was to compare the effectiveness of a femoral nerve block and a periarticular infiltration in the management of early post-operative pain after total knee arthroplasty (TKA). Patients and Methods. A pragmatic, single centre, two arm parallel group, patient blinded, randomised controlled trial was undertaken. All patients due for TKA were eligible. Exclusion criteria included contraindications to the medications involved in the study and patients with a neurological abnormality of the lower limb. Patients received either a femoral nerve block with 75 mg of 0.25% levobupivacaine hydrochloride around the nerve, or periarticular infiltration with 150 mg of 0.25% levobupivacaine hydrochloride, 10 mg morphine sulphate, 30 mg ketorolac trometamol and 0.25 mg of adrenaline all diluted with 0.9% saline to make a volume of 150 ml. Results. A total of 264 patients were recruited and data from 230 (88%) were available for the primary analysis. Intention-to-treat analysis of the primary outcome measure of a visual analogue score for pain on the first post-operative day, prior to physiotherapy, was similar in both groups. The mean difference was -0.7 (95% confidence interval (CI) -5.9 to 4.5; p = 0.834). The periarticular group used less morphine in the first post-operative day compared with the femoral nerve block group (74%, 95% CI 55 to 99). The femoral nerve block group reported 39 adverse events, of which 27 were serious, in 31 patients and the periarticular group reported 51 adverse events, of which 38 were serious, in 42 patients up to six weeks post-operatively. None of the adverse events were directly attributed to either of the interventions under investigation. Conclusion . Periarticular infiltration is a viable and safe alternative to femoral nerve block for the early post-operative relief of pain following TKA. Cite this article: Bone Joint J 2017;99-B:904–11

Aims

Unicompartmental knee arthroplasty (UKA) has been successfully performed in the United States healthcare system on outpatients. Despite differences in healthcare structure and financial environment, we hypothesised that it would be feasible to replicate this success and perform UKA with safe day of surgery discharge within the NHS, in the United Kingdom. This has not been reported in any other United Kingdom centres.

Aims

Multimodal infiltration of local anaesthetic provides effective control of pain in patients undergoing total knee arthroplasty (TKA). There is little information about the added benefits of posterior capsular infiltration (PCI) using different combinations of local anaesthetic agents. Our aim was to investigate the effectiveness of the control of pain using multimodal infiltration with and without infiltration of the posterior capsule of the knee.

Pain control is critical in the management of TKA patients and is crucial to allow for early ambulation and accelerated physical therapy. Currently data suggests that 19% of patients are not satisfied with their results following TKA, and failure to control pain may result in prolonged hospitalization, worse outcomes, and increased patient dissatisfaction. Studies suggest that local analgesics coupled with both pre- and post-operative multimodal pain management may result in improved pain control and increased patient satisfaction. Minimization of opioid use is helpful in decreasing complications, accelerating physical therapy milestones, minimizing length of stay and increasing discharge to home. Femoral nerve blocks (FNB) can reduce pain scores for up to 48 hours post-operatively, but may delay ambulation and result in an increased rate of falls. Periarticular injection (PAI) with local analgesics can provide significant short term relief comparable to FNB and can also facilitate decreased opioid consumption. One commonly used local anesthetic is bupivacaine, but the average half-life of this drug is only 2.7 hours. An alternative to this for PAI during TKA is liposomal bupivacaine (LB). LB is a multivesicular drug designed for rapid absorption, prolonged release of bupivacaine, and analgesia that is maintained for up to 72 hours with a single injection. LB exhibits a bimodal peak of distribution, one immediate associated with extra-liposomal bupivacaine, and a second 10–36 hours later associated with the release of liposomal encapsulated bupivacaine. The safety profile of LB has been investigated and adverse events are similar to standard bupivacaine and demonstrate acceptable tolerability. Multiple studies have demonstrated efficacy of this drug compared to other pain control modalities. LB is highly technique dependent and only one piece of a multimodal pain management protocol. Our study consisted of 1808 consecutive primary TKA patients from Sept 2013 to Sept 2015. Three patient cohorts were compiled by date, from Sept 2013 to May 2014 was cohort 1, consisting of FNB and PCA. Department wide adoption of LB began in May 2014 and became routinely used in all patients undergoing total joint arthroplasty at our institution. Cohort 2 entailed a PCA along with LB injection from May 2014 through Feb 2015. Cohort 3 consisted of LB injection only and was from Feb 2015 through Sept 2015. All patients undergoing TKA were eligible and there were no exclusion criteria as long as the protocols were followed. The standard multi-modal analgesia protocol was provided to all patients in all three cohorts. Prior to entering the operating room, patients received preemptive oral analgesics, consisting of: 200 mg celecoxib, 1000 mg acetaminophen, and 50 mg pregabalin. Intra-operative analgesia was chosen at the discretion of the anesthesiologist and preferentially consisted of spinal anesthesia with general anesthesia as an alternate. For all three cohorts, a peri-incisional analgesic cocktail was injected prior to closure consisting of: 40 cc 0.25% Marcaine, 5 cc of (1 mg/cc) morphine, and 1 cc of (30 mg/cc) ketorolac. Cohorts 1 and 2 received PCA post-operatively for pain control post-operatively with prn oral narcotic administration as well. Cohort 3 did not receive a PCA. The cohort treated without FNB and without a PCA using a multimodal pain management protocol including a short acting periarticular injection and a longer acting periarticular injection with LB, had equivalent pain control, less narcotic use, faster achievement of physical therapy milestones, earlier and more frequent discharge home, less complications and a lower cost of the episode of care

Introduction. Pain control following total knee arthroplasty (TKA) heavily influences timing of mobilization and rehabilitation postoperatively as well as length of hospital stay. Recently, periarticular injection of liposomal bupivacaine (EXPAREL®; Pacira Pharmaceuticals, Inc., San Diego, California) has demonstrated pain relief comparable to femoral nerve block for postoperative analgesia in TKA with earlier mobilization and shortened hospital stay. In order to better explore the use of EXPAREL® in TKA, we standardized the postoperative analgesia to intraoperative periarticular injection of multimodal pain management, which is a recommended postoperative method of pain control in TKA. We studied the effectiveness of periarticular EXPAREL® in TKA postoperative pain control, including impact on early mobilization and length of hospital stay, compared to another local analgesic (Ropivacaine) when both are used as part of a multimodal pain management approach. Methods. We performed a double blind, randomized, controlled, prospective, IRB-approved study that enrolled 96 participants who underwent a unilateral TKA by one surgeon between May 2014 and March 2015. The two randomized groups were as follows: group 1 (control group) was given the standard intra-articular “pain cocktail” injection, consisting of ropivacaine, ketorolac, morphine, and epinephrine mixed with saline into a 100cc preparation and group 2 (study group) was given a similar intra-articular injection consisting of bupivacaine, ketorolac, morphine, and epinephrine mixed with saline into an 80cc preparation as well as an injection of EXPAREL®, 20cc of 1.3% EXPAREL®, to total 100cc. All patients included in the study were determined to be opioid naïve as described by the Food and Drug Administration criteria. Patients were treated with the same postoperative pain management protocol as well as the same post-operative physical therapy program. The consumption of oral and intravenous narcotics at specific time points as well as total use was recorded during hospital stay. We recorded Visual Analog Pain scores, hours to ambulate 100 feet and length of hospital stay (hours). Both the investigator and the patient were blinded as to which group the patient was randomized, making this a double blind study. Results. On a per hour basis, the mean use of narcotics of the two groups differed by only 0.1mg. For total narcotic use during hospital stay, the weighted sum used by patients in the EXPAREL® group, 97.7mg of hydrocodone ±42.84 mg, exceeded the weighted sum, 89.6 mg of hydrocodone ± 58.57 mg, used by patients in the control group. The difference between the two groups was not significant. The means for length of stay differed by only 26 minutes and the difference was not significant. Similarly insignificant, the means for the time to ambulate 100 feet differed by 53 minutes, with the EXPAREL® group actually taking the longer time. The two groups did not differ for Visual Analog Score for pain on day 1 or day 2 post-operatively. Conclusion. When comparing the use of EXPAREL® to another multimodal pain management approach using ropivacaine, there is no difference in post-operative opioid consumption, Visual Analong Scores for pain, amount of time to ambulate or length of hospital stay

Robust evidence on the effectiveness of peri-operative local anaesthetic infiltration (LAI) is required before it is incorporated into the pain management regimen for patients receiving total knee replacement (TKR). To assess the effectiveness of peri-operative LAI for pain management in patients receiving TKR we conducted a systematic review, fully powered randomised controlled trial (RCT) and economic evaluation. We searched MEDLINE, Embase and Cochrane databases for RCTs of peri-operative LAI in patients receiving TKR. Two reviewers screened abstracts and extracted data. Outcomes were pain, opioid use, mobilisation, hospital stay and complications. Authors were contacted if required. When feasible, we conducted meta-analysis with studies analysed separately if a femoral nerve block (FNB) was provided. In the APEX RCT, we randomised 316 patients awaiting TKR to standard anaesthesia which included FNB, or to the same regimen with additional peri-operative LAI (60mls 0.25% bupivacaine plus adrenaline). Post-operatively, all patients received patient-controlled morphine. The primary outcome was joint pain severity (WOMAC-Pain) at 12 months. Patients and outcome assessors were blinded to allocation. Within APEX, cost-effectiveness was assessed from the health and social-care perspective in relation to quality adjusted life years (QALYs) and WOMAC-Pain at 12-months. Resource use was collected from hospital records and patient questionnaires. In the systematic review, 23 studies including 1,439 patients were identified. Compared with patients receiving no intervention, LAI reduced WOMAC-Pain by standardised mean difference (SMD) −0.40 (95%CI −0.58, −0.22; p<0.001) at 24 hours at rest and by SMD −0.27 (95%CI −0.50, −0.05; p=0.018) at 48 hours during activity. In three studies there was no difference in pain at any time point between randomised groups where all patients received FNB. Patients receiving LAI spent fewer days in hospital, used less opioids and mobilised earlier. Complications were similar between groups. Few studies reported long-term outcomes. In the APEX RCT, pain levels in hospital were broadly similar between groups. Overall opioid use was similar between groups. Time to mobilisation and discharge were largely dependent on local protocols and did not differ between groups. There were no differences in pain outcomes between groups at 12 months. In the economic evaluation, LAI was marginally associated with lower costs. Using the NICE £20,000 per QALY threshold, the incremental net monetary benefit was £264 (95%CI, −£710, £1,238) and the probability of being cost-effective was 62%. Although LAI appeared to have some benefit for reduced pain in hospital after TKR there was no evidence of pain control additional to that provided by femoral nerve block, however it would be cost-effective at the current NICE thresholds