What’s New in Hip Surgery

The trend of high-quality publications exploring the orthopaedic management of hip pathology has continued since the last iteration of this Guest Editorial. Common themes of this update include preoperative and perioperative management in total hip arthroplasty (THA), perioperative pain control, and emerging technologies. It is imperative that today's hip surgeon remain knowledgeable about these rapidly expanding topics. Preoperative Considerations in THA Punnoose et al. published the results of a systematic review and meta-analysis involving 48 trials (3,570 patients) comparing prehabilitation with standard preoperative care in adults undergoing orthopaedic procedures1. Pain, muscle strength, function, health-related quality of life, and disease-specific and/or joint-specific outcomes were assessed for THA (among other orthopaedic procedures). In the preoperative setting, there was moderate-certainty evidence favoring prehabilitation in THA over standard care for the outcomes of hip abductor strength and health-related quality of life. In addition, there was low-certainty evidence favoring prehabilitation over standard care for the outcomes of pain and function. At 3 and 12 months postoperatively, there was low-certainty evidence favoring prehabilitation over standard care in THA, with a smaller benefit for patients undergoing THA compared with total knee arthroplasty (TKA). Similarly, in a recent article, Adebero et al. analyzed 28 trials to assess the effectiveness of prehabilitation on outcomes following THA2. Pain, health-related quality of life, strength, range of motion, and function were all significantly improved in patients receiving prehabilitation prior to TKA. In contrast, the trials addressing THA were limited and contradictory. Evidently, prehabilitation may have some role in improving the preoperative status of patients who will undergo THA, whereas the postoperative benefits are less substantial. Prehabilitation may be more useful in patients who undergo TKA than in those who undergo THA based on current evidence, with a potential, but limited, benefit in THA. Perioperative Management Postoperative drainage after hip and knee replacement can be problematic for patients and surgeons. In their secondary analysis of their Australian Orthopaedic Association National Joint Replacement Registry-based study, Sidhu et al.3 examined whether enoxaparin compared with aspirin was associated with increased postoperative wound drainage. In the cluster-randomized, crossover, noninferiority, nested registry trial (CRISTAL4), 31 institutions across Australia examined the prevalence of deep vein thrombosis in patients. Sidhu et al. took the results from 2 of the high-volume centers participating in this trial and examined them for wound complications. The included patients received 100-mg aspirin or 40-mg enoxaparin daily for 35 days after hip replacement and for 14 days after knee replacement. They found that overall persistent wound drainage did not differ (p = 0.40) between groups: 8% for the aspirin group and 9% for the enoxaparin group (odds ratio [OR], 1.2). However, in those patients who underwent a subcuticular closure, persistent wound drainage was observed in 7.7% of patients taking enoxaparin and 2.4% of patients taking aspirin (OR, 3.6; p = 0.009). This difference was not observed in those patients who underwent skin staple closure, and there was no difference in reoperations. The authors did advise caution when interpreting these results given the small sample size and the presence of effect modification by the thromboprophylaxis agent and type of wound closure, which prevented full model analysis. Intraoperative hemostasis remains a topic of discussion. Tranexamic acid (TXA) is widely adopted as a perioperative agent utilized to decrease perioperative blood loss in major orthopaedic operations. In a Cochrane Review, Gibbs et al. aimed to determine which of the commonly utilized perioperative agents (intravenous or oral TXA and recombinant factor VIIa) used in blood loss prevention were effective at reducing bleeding in patients requiring definitive fixation for hip, pelvic, and long-bone fractures5. The authors found that intravenous administration of TXA compared with placebo may reduce the risk of requiring allogenic blood products for 30 days postoperatively (risk ratio [RR], 0.48 [95% confidence interval (CI), 0.34 to 0.69]; 6 randomized controlled trials [RCTs], 457 participants), but with a low degree of certainty due to statistical imprecision. Additionally, the authors were uncertain if topical TXA compared with placebo resulted in fewer transfusions or less all-cause mortality, and they could not analyze factor VIIa because of a lack of evidence. The risk assessment tools for the development of deep vein thrombosis and pulmonary embolism are of particular use to the arthroplasty community. The Caprini score is a commonly used tool to predict the risk of the subsequent development of deep vein thrombosis or pulmonary embolism after a surgical intervention. Arthroplasties themselves automatically result in a patient score that is a minimum of 5 on this scale, and, as such, the effectiveness of this scale as a predictive tool in this population has been questioned. Qiao et al. aimed to answer this question via their study of 7 years of data on venous thromboembolism6. In their study, the authors included 3,807 patients who had undergone preoperative and postoperative ultrasonography on postoperative days 3 to 5, making it the largest study to date. The authors found a strong correlation between a greater Caprini score and venous thromboembolism (r = −0.775; p = 0.003); however, they noted that the receiver operating characteristic (ROC) curve had a poor area under the curve (AUC) of 0.619, confirming that the Caprini score is not prognostic. They determined that a Caprini score of ≥8.5 suggested a high risk of venous thromboembolism and recommended appropriate prophylaxis for high-risk patients. However, it is worth noting that the Youden index associated with their chosen cutoff was 0.175, which indicates only a modest level of effectiveness for a diagnostic test. In addition, 92.4% of the deep vein thromboses were located below the knee and were "muscular," which has debatable clinical importance. The authors confirmed a strong correlation; however, the precise cutoff value for an increased regimen of thromboprophylaxis in the population undergoing arthroplasty remains debated. As the lower-extremity ultrasound scan was performed on postoperative days 3 to 5 and not beyond, deep vein thrombotic events occurring after this would have been missed, which limited the interpretation of the results. Perioperative Pain Control Nerve Blockade There have been numerous high-quality studies recently published on pain control in the perioperative period. Bravo et al. conducted an RCT comparing a pericapsular nerve group block with periarticular anesthetic infiltration after spinal anesthesia7 and found no difference in terms of the quadriceps motor blockade at any time point postoperatively. This was unexpected and was thought to be due to the questionable power of the study to adequately detect the difference and the multifactorial nature of quadriceps weakness in the postoperative period. The periarticular anesthetic infiltration resulted in lower static pain scores at all time intervals postoperatively (range of visual analog scale [VAS] difference, 0 to 2), in addition to lower dynamic pain scores (with adduction) at 3 and 6 hours (VAS difference, 2). There were no differences in opioid requirements in the postoperative period. The authors concluded that the increased success of the periarticular anesthetic infiltration block was due to its coverage of the posterior tissues, which was deficient in the pericapsular nerve group block. Alternatively, some researchers are considering quadratus lumborum blockage as a pain control strategy. Takeda et al.8 compared quadratus lumborum blockage with femoral nerve blockage in their RCT and found no significant difference in cumulative morphine consumption (p = 0.72) or intraoperative morphine consumption (p = 0.26). The authors could not show a clear superiority of quadratus lumborum blockage over femoral nerve blockage with respect to postoperative strength or fall risk. There was a debate in a subsequent letter to the editor regarding concerns over the sample size for that study9. In their RCT, Umeh et al.10 examined quadratus lumborum blockage compared with periarticular anesthetic infiltration in the population undergoing hip arthroscopy but did not find any differences in postoperative opioid consumption (p > 0.05) or a difference in postoperative quadriceps weakness (p = 0.2). As the baseline pain after THA tends to be low and variable, the concern regarding the above studies is that they would be underpowered to detect minor differences in analgesic effect. Oral Pain Medication Oral analgesia to decrease opioid consumption after joint replacement is an attractive adjuvant. Duloxetine has been classified as a selective serotonin and norepinephrine reuptake inhibitor (SSNRI) and has been previously investigated for its action after joint replacement. Azimi et al.11 investigated its postoperative role in their systematic review and meta-analysis of the current high-level evidence. After including 9 Level-I RCTs, the authors determined a significant and moderate decrease in oral morphine milligram equivalents and a lower overall pain level at several time points; however, they called into question the clinical importance of the latter, given that the reduction did not meet the minimal clinically important difference. There was also significant heterogeneity in the results, creating a low certainty of evidence. The authors concluded that the use of duloxetine may reduce the intensity of pain; however, they also concluded that "the current evidence does not support routine use for the sole purpose of reducing post-operative pain" and that its potential opioid-sparing effects must be weighed against the side effects. Meanwhile, in their RCT, Shen et al.12 assessed the impact of TXA on opioid use by comparing oral administration with intravenous administration. The authors enrolled 161 patients and assessed pain in the first 3 days via a VAS score and postoperative tramadol consumption. They also measured C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), and interleukin-6 (IL-6) daily for the first 3 days, as inflammatory markers. They found that topical TXA appeared to yield a lower VAS score, as well as lower CRP, ESR, and IL-6 measurements. The results should be interpreted with caution, however, as the differences in the VAS score, CRP, ESR, and IL-6 were minimal, which questions their clinical importance. In addition, preoperative levels were not measured, and spinal anesthesia compared with general anesthesia did not appear to be controlled for. It is plausible that topical TXA may reduce hematoma formation, which, in turn, may decrease postoperative pain and may reduce inflammatory markers; however, more research is required to answer this interesting question. Hip Fracture Management Displaced Femoral Neck Fracture In a recent study by Lynch Wong et al., the rates of postoperative periprosthetic femoral fractures after THA with cemented polished taper-slip stems (0.9%) were higher than with cementless stems (0.7%)13. Of note in this study, male patients with a polished tapered femoral component were 5 times more likely to have a reoperation for postoperative periprosthetic femoral fracture compared with male patients with a cementless stem. The concerns around postoperative periprosthetic femoral fractures with these stems are relatively new and should be monitored closely in future studies, particularly in international registry reports, as categorization by THA versus open reduction and internal fixation (ORIF) may mask the identification of cases. In a recent systematic review and network meta-analysis of 5,703 displaced and nondisplaced femoral neck fractures, Ramadanov et al. demonstrated a superior functional outcome (EuroQol-5 Dimensions [EQ-5D] and Harris hip scores) for both hemiarthroplasty and THA14. The reoperation rate was highest for cannulated screws (9.98 times higher), followed by a dynamic hip screw (5.07 times higher). There was no difference in reoperation rate between hemiarthroplasty and THA. This analysis did not discriminate between displaced and nondisplaced femoral neck fractures and, as such, more focused research is required. However, these results potentially support the use of arthroplasty for all femoral neck fractures, regardless of displacement. Nondisplaced Femoral Neck Fracture Adding to the literature on management of nondisplaced femoral neck fractures, Sattari et al. reported on their results comparing internal fixation and hemiarthroplasty for the management of Garden type-I and II (nondisplaced) femoral neck fractures15. The 6-month Harris hip score (p = 0.009) and the 1-year EQ-5D (p = 0.04) were significantly better in the hemiarthroplasty group. Internal fixation, compared with hemiarthroplasty, also had a higher rate of implant-related complications (20.1% compared with 6.0%; p = 0.0002) and reoperations (20.1% compared with 6.0%; p = 0.0001). Hemiarthroplasty for nondisplaced femoral neck fractures had disadvantages with regard to blood loss and operative duration. Perioperative Interventions in Hip Fracture Management Perioperative optimization is critical in the hip fracture setting. Several recent systematic reviews have focused on this area of clinical interest for this particularly fragile patient cohort. Lewis et al. summarized the evidence from Cochrane Reviews and other systematic reviews of randomized or quasi-randomized trials to assess the perioperative interventions that may lead to reduced blood loss, rates of anemia, and need for blood transfusion in patients with a hip fracture16. This Cochrane Review included results from 36 RCTs involving 3,923 participants. The 2 interventions of interest were TXA and iron. TXA It was determined that TXA, given topically or intravenously, likely reduced the number of patients requiring transfusion by 194 per 1,000. The risk profile of TXA administration was assessed and was found to be minimal to none with regard to deep vein thrombosis (RR, 1.16; 22 studies), pulmonary embolism (RR, 1.01; 9 studies), myocardial infarction (RR, 1.00; 8 studies), stroke (RR, 1.45; 8 studies), or death (RR, 1.01; 10 studies). Iron Based on 2 studies with 403 participants, there was deemed to be little to no difference in outcomes when iron was administered in the perioperative period. The risks of negative outcomes such as transfusion (RR, 0.90), infection (RR, 0.99), and 30-day mortality (RR, 1.06) were similar when intravenous iron was administered compared with when it was not. However, because the iron results were based on only 2 studies, the ability to draw any meaningful conclusions was limited. Postoperative Interventions in Hip Fracture Management Phang et al. reviewed 109 RCTs involving an array of postoperative interventions in patients >65 years of age who sustained a non-pathological hip fracture in which surgical management was adopted17. The following 10 broad categories of intervention were considered: (1) rehabilitation; (2) medication, nutrition, and supplementation; (3) optimization of clinical management; (4) prevention of venous thromboembolism; (5) a multidisciplinary program; (6) osteoporosis or fracture prevention; (7) fall prevention; (8) prevention of postoperative anemia; (9) supported discharge; and (10) other. Each of these categories was further divided into 3 subgroups based on whether the intervention occurred on an inpatient basis, an outpatient basis, or both. The interventions for which only positive outcomes were reported are listed, by category, in Table I. TABLE I - Interventions with Exclusively Positive Outcomes, by Category of Intervention Intervention Inpatient Outpatient Inpatient and Outpatient Rehabilitation Aerobic trainingSpecialized physical rehabilitationWeight-bearing exerciseTreadmill trainingTranscutaneous electrical nerve stimulationSpecialized geriatric rehabilitationProgressive high-intensity trainingIntensive physiotherapyNeurostimulationIndividualized occupational therapyBalance task-specific trainingEarly ambulation Resistance trainingStrength trainingPhysical training and self-efficacyHome physiotherapySelf-efficacy-based exerciseTelerehabilitationWeight-bearing exercise Extended physical therapyIndividualized occupational therapyWeight-bearingCognitive behavioral therapyAccelerated rehabilitation Medication, nutrition, and supplementation Nutritional supportDietetic assistantsGrowth hormoneEssential amino acid supplementationVitamin D Essential amino acid supplementationVitamin D Nutritional support with dietetic counselingBone anabolic drugVitamin D and calciumAnabolic corticosteroidsIntranasal calcitonin Optimizing clinical management Physiotherapy educationManagement of painManagement of postoperative delirium None None Prevention of venous thromboembolism None None Fondaparinux sodiumAntithrombotic agent Multidisciplinary program Orthopaedic and geriatric care Multidisciplinary Intensive geriatric rehabilitationEarly discharge supported by geriatric interdisciplinary team Osteoporosis or fracture prevention None None Primary care and patient empowermentVitamin D and/or calciumOsteoporosis management Fall prevention Multicomponent cognitive behavioral interventionMultidisciplinary care Follow-up call Home assessment visit pre-discharge Postoperative anemia None None None Supported discharge None None Gerontologic advanced practice nurse care Other None Group learning and exerciseMotivational interviewing None Hip Preservation Systematic reviews and meta-analyses have been the focus of several recent hip preservation-themed studies. In their systematic review of mid-term outcomes of labral reconstruction, Curley et al.18 found that there was a trend of improved patient-reported outcomes in all included studies. However, there was significant heterogeneity with respect to approach, reconstruction indications, and allograft choice, which precluded a pooled analysis. The authors also acknowledged that the inclusion of Level-III and IV studies introduced bias to the overall results. Labral reconstruction may offer durable results in carefully chosen patient populations, but the optimal approach could not be determined. Although more commonly studied in knees, Dhillon et al.19 examined how microfracture for chondral defects compared with other cartilage repair methods in the management of femoral acetabular impingement. Six studies were included, all with low levels of evidence. In addition, there was a heterogeneous group of comparative cartilage procedures and lesion sizes. All included studies had moderate bias with respect to confounding and severe bias with respect to measurement of the outcome. Although they concluded that microfracture was not inferior to other methods with respect to patient-reported outcomes, the authors emphasized that the available literature was limited in its ability to address the research question. With regard to capsular repair, Kaplan et al.20 also conducted a systematic review to determine how the management of the hip capsule during hip arthroscopy for femoral acetabular impingement influences patient-reported outcome measures or re-revision surgery. The 4 included studies all represented Level-III evidence, and a pooled analysis was not possible given their heterogeneity. The authors found similar patient-reported outcome measures in the capsular repair group compared with the group that did not undergo capsular repair. The authors also found that an unrepaired capsule appeared to yield greater rates of re-revision hip arthroscopies (range, 15.4% to 25.5%) compared with a repaired capsule (range, 3.1% to 15.4%). However, the authors suggested that this result should be interpreted with caution, given the degree of heterogeneity and bias within the included studies that may have led to confounding and spurious results. Periprosthetic Joint Infection (PJI) There has been considerable discussion on the timing of corticosteroid injections prior to arthroplasty, and the results have been conflicting. To answer this question, Albanese et al.21 performed a meta-analysis of the available literature. They included 28 articles on hip and knee arthroplasty, most of which were Level-III and IV evidence, except for 2 Level-II studies. There were 61,049 patients pooled from the population undergoing hip arthroplasty. The authors found an overall PJI rate of 1.4% in the corticosteroid group and 0.8% in the control group (p = 0.001); OR, 1.55 (95% CI, 1.357 to 1.772); I2: −14%. Interestingly, an increased risk of infection was not found in the population undergoing knee arthroplasty. The authors also found that having a corticosteroid injection within 3 months prior to hip or knee arthroplasty increased the risk of infection (2.0% compared with 1.6%; p = 0.045; OR, 1.20 [95% CI, 1.058 to 1.347]; I2: 29%). However, the authors conceded that the results should be interpreted with caution given the inherent bias, lack of standardization, and heterogeneity in the included studies, and they suggested that the current state of literature could not yet adequately answer this question. They recommended caution on the timing of corticosteroid injection with respect to arthroplasty, but called for higher-quality evidence to adequately address this question. To address another highly controversial and discussed topic, an RCT by Agni et al. examined whether high-dose, dual-antibiotic cement lowered the infection rate after hemiarthroplasty compared with standard-of-care, single-antibiotic-loaded cement at 90 days22. In their multicenter superiority trial, 4,936 patients were enrolled to receive either single-antibiotic-loaded cement (50-mg gentamicin) or dual-high-dose-loaded cement (1 g each of gentamicin and clindamycin). The authors found an infection rate of 1.7% for the standard-dose group and 1.2% for the high-dose group. After their mixed-effects logistic model was applied, they found a risk difference for deep surgical site infection in the standard group of 0.52 (95% CI, –0.19 to 1.23) and an OR of 1.43 (95% CI, 0.87 to 2.35; p = 0.16) when compared with the high-dose group. Interestingly, these results disagree with previous studies on the subject; however, this study has the largest sample size. In a first-of-its-kind study for assessing intraosseous vancomycin in THA, Harper et al. conducted a randomized, single-blinded, controlled study comparing intravenous administration (15 mg/kg) 1 hour prior to skin incision with injection of 500 mg in 100 mL of normal saline solution into the greater trochanter at the time of skin incision23. They noted that, when patients were given vancomycin via intraosseous administration, there was a significant reduction in serum vancomycin levels. Despite this, all tissue (gluteus maximus and pulvinar) and bone samples (femoral head, acetabular reamings, medullary canal) had higher levels of vancomycin in the intraosseous group compared with the intravenous group; however, only the levels in the acetabular reamings showed a significant difference. The study was not able to conclude if this resulted in a clinically different infection risk. Implant Design and Related Outcomes Bearing Surface in THA The advent of highly cross-linked polyethylene (HXLPE) is arguably the most noteworthy advancement in recent orthopaedic history because of its minimization of complications related to polyethylene wear. As a result, HXLPE has allowed the safe use of large femoral heads, resulting in a positive impact on prosthetic hip stability. Fransen et al. published results from 2,565 THAs in which HXLPE liners were used24. At a follow-up range of 11 to 19 years, liner thickness did not influence all-cause, revision-free survival, and there was no clinically importance difference in liner thickness between those patients who required a reoperation or any revision and those who did not. In some cases, the liner was as thin as 4.9 mm. The advantage of using thin liners includes the ability to use larger femoral heads, which, in turn, increases the jump distance and inherent prosthetic hip stability. Subsequently, Fransen et al. also published the results of using 36-mm femoral heads within a 52-mm acetabular component or smaller. They reported that, at mid-term follow-up, linear wear, volumetric wear, and survivorship rates were all excellent25. In a network analysis, Zheng et al. demonstrated that liners consisting of HXLPE, vitamin E-infused HXLPE, or ceramic had a comparable survivorship, and all of them were superior to conventional polyethylene (ultra-high molecular weight polyethylene [UHMWPE])26. This study confirmed higher revision rates for metal and ceramic on UHMWPE compared with metal and ceramic on HXLPE. There were smaller femoral-head sizes and inferior Harris hip scores when metal or ceramic on UHMWPE bearings were used compared with all other bearing combinations. In summary, large femoral heads and HXLPE acetabular liners are now becoming the standard of care in THA. Femoral Stem Fixation The mode of fixation of the femoral stem in THA can vary between cemented and cementless. Cemented stems include the highly polished taper-slip and composite-beam options. In a recent prospective RCT, Gaston et al. analyzed 220 polished taper-slip cemented femoral stems, of which 110 were assigned to a shorter (125-mm) stem group and 110 were assigned to a longer (150-mm) stem group27. Functional outcomes were deemed equivalent between the 2 groups. Radiographic outcomes were also assessed, and the coronal alignment in the group with the shorter stem was reported to be in 0.9° greater varus compared with the longer-stem group. Anticipation of femoral anatomy that may predispose to varus-aligned stems is crucial. A novel femoral access ratio described by Sheridan et al. describes the impact that a low greater trochanteric height can have in causing varus-aligned femoral stems28. With a femoral access ratio of <1, the risk of varus malalignment can be as high as 68%. The risks of varus malalignment include femoral stem fracture. Turnbull et al. reported an increased risk of cemented or cementless femoral stem fracture (OR, 5.77 [95% CI, 3.83 to 8.7]; p < 0.001) with varus stem malalignment, and so this should be avoided where possible29. New Technologies in Hip Surgery Digital Rehabilitation The concept of mobile rehabilitation programs has increasingly been studied. In their single-blinded study, Wang et al. compared conventional rehabilitation with a mobile app-based program in patients undergoing THA or TKA30. The authors found significantly improved scores for self-efficacy (p < 0.001), health-related quality of life (p = 0.018), anxiety (p = 0.015), and depression (p = 0.012) at 10 weeks. However, the authors commented on the overall small effect size as well as the mixing of patients who were undergoing THA and patients who were undergoing TKA that made subgroup analysis unreliable. As such, further research is required to answer this interesting question. In an RCT of 26 patients, Osterloh et al. considered if digital group-therapy rehabilitation was beneficial30. Despite the small sample size and most functional outcome measurements not reaching significance, some categories including the EQ-5D and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) had a larger effect size in favor of digital rehabilitation. Methodologically, despite an RCT design, this study was not designed well enough to answer this question, and the results can be considered as preliminary at best. Augmented Reality The cutting-edge development of augmented reality has been increasingly studied. In their RCT, Tanino et al. compared the cup position and functional outcomes of a standard posterior approach with and without an augmented-reality adjunct via the use of an intraoperative smartphone in a sterilized case32. The authors found that, with augmented reality, cups were more frequently placed in the Lewinnek safe zone (p < 0.001), and there were no major differences in complications between groups. However, the authors acknowledged that functional pelvic tilt and the questionable clinical relevance of the Lewinnek safe zone are factors to consider when interpreting the results. The dislocation rate, which ultimately is the most important variable, was not studied, making this study less impactful. Evidence-Based Orthopaedics The editorial staff of JBJS reviewed a large number of recently published studies related to the musculoskeletal system that received a higher Level of Evidence grade. In addition to articles cited already in this update, 7 other articles relevant to hip surgery are appended to this review after the standard bibliography, with a brief commentary about each article to help guide your further reading, in an evidence-based fashion, in this subspecialty area. Evidence-Based Orthopaedics Gao YH, Wang XY, Zhao XY, Zang JT, Yang C, Qi X. Prevention of pregabalin-related side effects using slow dose escalation before surgery: a trial in primary total joint arthroplasty within the enhanced recovery after surgery pathway. J Arthroplasty. 2023 Aug;38(8):1449-54. The use of pregabalin has been explored to improve postoperative pain control and reduce opioid consumption after joint arthroplasty. It has also been associated with side effects including respiratory depression and sedation. In their prospective RCT, Gao et al.