BACKGROUND: Iliopsoas impingement after total hip arthroplasty can result not only from acetabular cup but also from cup fixation screw. However, research addressing this screw impingement is scarce, leaving the details undetermined. This study aimed to elucidate the incidence and threshold of symptomatic iliopsoas impingement attributable to protrusion of the cup fixation screw into the iliopsoas muscle and to evaluate its impact on postoperative radiographic imaging findings and patient-reported outcome measures.
METHODS: A total of 152 hips were included in this study. The symptomatic threshold of screw protrusion was determined using a receiver operating characteristic curve, and patients were divided into low-protrusion and high-protrusion groups using this threshold. The area and Hounsfield Unit values of the iliopsoas muscle on CT and the Japanese Orthopaedic Association Hip Disease Evaluation Questionnaire postoperatively were investigated.
RESULTS: 10 hips (6.5%) were exhibited symptoms of IPI in this series. The threshold for screw protrusion length was identified as 6.4 mm. Patients in the high protrusion group exhibited significantly larger area and lower Hounsfield Unit values of the iliopsoas muscle. In addition, the high protrusion group revealed significantly lower scores (total, pain, movement, mental). Furthermore, subscales scores (pain, movement) in the high protrusion group didn\'t improve from 3 months to 12 months postoperatively with significance.
CONCLUSIONS: This study underscores the imperative for surgeons to consider the length of the cup fixation screw. This careful consideration is crucial for mitigating the incidence of postoperative iliopsoas impingement and enhancing total hip arthroplasty outcomes.

BACKGROUND: Hip replacement surgery is highly effective in relieving pain and improving mobility in patients with various hip conditions. However, some patients develop groin pain after surgery, often due to iliopsoas impingement (IPI), which can be challenging to diagnose. Conservative treatments are initially recommended, but when these are not effective, surgical options may be considered. This study aims to evaluate the clinical outcomes, success and failure rates, revision rates, and complications associated with arthroscopic and endoscopic surgery for IPI, thereby providing a comprehensive understanding of the effectiveness and risks of these surgical interventions.
METHODS: A systematic review was conducted following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, including a thorough search of five main databases: PubMed, Scopus, Embase, Medline, and Cochrane. Eligible articles were meticulously evaluated according to predefined criteria for levels of evidence (LoE), with retrospective studies assessed using the Coleman Methodology Score (mCMS). This systematic review was registered in the International Prospective Registry of Systematic Reviews (PROSPERO).
RESULTS: Among the 16 included studies, 431 patients with 434 hips underwent either endoscopic or arthroscopic tenotomy. Both techniques showed favorable outcomes, with arthroscopic tenotomy demonstrating slightly higher success rates than endoscopic tenotomy. Common complications included mild pain and occasional infections, with recurrence observed in some cases. Both techniques offer direct visualization of prosthetic components and potential preservation of psoas function.
CONCLUSIONS: Arthroscopic and endoscopic iliopsoas tenotomy are effective treatments for alleviating symptoms and improving hip function in patients with IPI post-total hip arthroplasty (THA).
METHODS: IV.

In most cases, impingement of the iliopsoas tendon after total hip arthroplasty is caused by acetabular component retroversion. The present case report describes a patient with functional iliopsoas impingement following total hip arthroplasty. With increasing flexibility of the hip joint after surgery, the functional adjustment to the stiff thoracolumbar spine in this patient with diffuse idiopathic skeletal hyperostosis resulted in progressive pelvic roll back. This roll back resulted in a functional iliopsoas impingement as the psoas tendon travels over the front of the pecten ossis pubis. Since excessive roll back is usually also addressed in primary total hip arthroplasty by decreasing anteversion of the acetabular component, surgeons should be aware to avoid the combination of roll back and decreased anteversion and their potential impact on iliopsoas impingement.

UNASSIGNED: Although numerous studies have reported outcomes with various conservative approaches for the iliopsoas impingement after total hip arthroplasty (THA), reports on the use of locoregional autologous platelet rich plasma (PRP) injections for the iliopsoas impingement after THA are lacking. This phase 1 study therefore aimed to investigate the safety and feasibility of locoregional PRP injection for iliopsoas impingement after THA.
UNASSIGNED: Patients diagnosed with iliopsoas impingement after THA who met the criteria for participation (symptoms persisting for more than 3 months, aged 20 years or older, and unable to receive non-steroidal analgesic or anti-inflammatory drugs) were eligible to participate in this clinical study. The primary endpoint was observed adverse events including procedure-related pain, and the secondary endpoints included pain and functionality of the hip joint, that were assessed using the Western Ontario and McMaster Universities Arthritis Index, Japanese Hip Disease Evaluation Questionnaire, and Forgotten Joint Score-12.
UNASSIGNED: Three patients were screened for eligibility, and 3 patients were finally included in this study. Two participants (patients 1 and 2; aged 66 and 65 years, respectively) were female. The third participant (patient 3; age 73 years) was male. All patients experienced adverse events; however, none were found to be serious. None of the patients experienced any infections, or intra- or post-operative symptoms of nerve damage, or subcutaneous haemorrhage owing to the administration of locoregional PRP. Although patient 2 showed almost complete resolution of the symptom, patient 1 and 3 demonstrated persistent groin pain after the injection.
UNASSIGNED: We demonstrated the results of preliminary phase 1 prospective observational clinical study that administration of locoregional PRP injections for iliopsoas impingement following THA is both, safe and feasible.

BACKGROUND: In 2015, we described a capsule-thickening technique via an anterior approach for iliopsoas cup impingement. To our knowledge, medium-term results have not been reported. We therefore retrospectively analyzed all cases in the initial series and those since 2015, to assess this original technique over a longer follow-up: (1) to analyze complications, and (2) to assess functional outcome.
OBJECTIVE: The study hypothesis was that this surgical solution has a success rate sufficient for it to be included in the therapeutic armamentarium for iliopsoas impingement.
METHODS: Fourteen patients were included. Nine plasties were in first line, 3 after tenotomy, and 2 after cup exchange. The anterior Hueter approach was used, visualizing anterior cup overhang, sometimes associated with penetration of the anterior capsule, and enabling capsule-thickening by a folded Vicryl™ mesh. Functional results were analyzed.
RESULTS: At a median 4years\' follow-up (IQR: 2-5; range: 1-9), change over baseline in Oxford score was 7 points (p=0.004), median Medical Research Council thigh flexion strength score was 5 (IQR: 5-5), and 50% of patients (7/14) were satisfied or very satisfied. The major complications rate was 7% (1/14), for 1 irrigation of infected hematoma, cured without recurrence; there was also 1 minor case of injury to the lateral cutaneous nerve of the thigh. Forty-three percent of patients (6/14) exhibited a minimal clinically important difference (MCID) and 64% (9/14) a patient-acceptable symptom state (PASS). Median anatomic overhang on anatomic CT transverse slice was 7mm (IQR: 3-8; range: 0-13). Four patients underwent secondary acetabular component exchange; their median overhang was 7.5mm (IQR: 7-8) compared to 5mm (IQR: 2-8) for the other patients (p-value non-calculable).
CONCLUSIONS: This surgical option seems interesting when acetabular overhang is not too great, especially as it does not affect flexion strength.
METHODS: IV.

Iliopsoas impingement (IPI) is an important complication after total hip arthroplasty (THA), and anterior cup protrusion is believed to be its main cause; however, the relationship between the hip center of rotation (COR) and symptomatic IPI or cup protrusion remains poorly understood. Therefore, the present study investigated these relationships.
The medical records of 138 patients who underwent unilateral primary THA were retrospectively reviewed. There were 8 patients (5.8%) who had symptomatic IPI. The COR and cup protrusion length measured with 2 methods were assessed on computed tomography. Risk factors for symptomatic IPI and the relationship between the COR and protrusion length were evaluated.
Logistic regression analyses showed that anteroposterior position of the COR, sagittal cup protrusion length (SCPL) at the COR, and both axial and SCPLs at the most anterior margin of the cup were related to symptomatic IPI. Multivariable regression analyses showed that acetabular offset was related to axial protrusion length at the COR, and anteroposterior position of the COR was related to both axial and sagittal protrusion lengths at the most anterior margin of the cup.
Anterior position of the cup was related to symptomatic IPI and both axial and sagittal protrusion lengths at the most anterior margin of the cup. Anterior reaming and cup protrusion should be avoided as much as possible to prevent symptomatic IPI.

Cup overhanging in total hip arthroplasty is a predisposing factor to iliopsoas impingement. In dysplastic hips, cup implantation was simulated in an anatomic hip center of rotation (AHCR) and in high hip center (HHCR). We sought to assess: (1) the percentage of prominent cups; (2) quantify the cup protrusion at different sites on frontal, axial and sagittal views. In 40 Crowe III-IV hips, using a 3D CT-based planning software, cup planning in AHCR and HHCR (CR height ≥ 20 mm) was performed for every hip. Cup prominence was assessed on every plane. HHCR cups were less anteverted (p < 0.01), less medialized (p < 0.001) and less caudal (p = 0.01) than AHCR sockets. AHCR cups were more frequently prominent on at least one plane (92.5% vs. 77.5%), with minimal agreement between the two configurations (k = 0.31, p = 0.07). AHCR cups protruded more than HHCR sockets in the sagittal (p = 0.02) and axial planes (p < 0.001). Axially, at the center of the cup, prominence 6−11 mm occurred in nine (22.5%) AHCR and one (2.5%) HHCR socket. In conclusion, while a routine high hip center should not be recommended, cup placement at a center of rotation height < 20 mm is associated with higher rates and magnitudes of anterior cup protrusion in severe dysplasia.

OBJECTIVE: To evaluate the outcome of arthroscopic treatment for iliopsoas impingement after total hip arthroplasty (THA) 2 years after surgery using patient reported outcomes (PROM).
METHODS: In this study 12 patients (13 hips) were included from a local hip arthroscopy registry. Patients completed web-based PROMs preoperatively and at a minimum of 2 years postoperatively. The PROMs included the International Hip Outcome Tool short version (iHOT-12), the Copenhagen Hip and Groin Outcome Score (HAGOS), the European Quality of Life-5 Dimensions Questionnaire (EQ-5D), the Hip Sports Activity Scale (HSAS) for physical activity level, the Visual Analog Scale (VAS) for overall hip function and a single question regarding overall satisfaction with the surgery.
RESULTS: The mean age was 64.4 years (±15.1SD), mean body mass index (BMI) was 26.6 (±4.3SD), mean follow-up time was 49.8 months (±25SD). Comparing PROMs preoperatively with 2-year follow up showed an improvement for many of the PROMs used. The PROMs scores were iHOT-12 (24.9 vs 34.5, p = 0.13), HAGOS subscales (symptoms 38.2 vs 54.5, p = 0.05; pain 36 vs 53, p = 0.04; sport 14.1 vs 35.1, p = 0.03; daily activity 31 vs 47.5, p = 0.04; physical activity 21.8 vs 24, p = 0.76; quality of life 24 vs 35, p = 0.03), EQ-VAS (57.9 vs 58, p = 0.08), EQ-5D (0.34 vs 0.13, p = 0.07) and VAS for overall hip function (43.1 vs 46.2, p = 0.14). In total, 10 out of the 12 patients (83%) were satisfied with the intervention.
CONCLUSIONS: Patients undergoing surgery for iliopsoas impingement after previous THA showed improved self-reported hip function where most patients were satisfied with treatment.

OBJECTIVE: Iliopsoas impingement occurs in 4% to 30% of patients after undergoing total hip arthroplasty (THA). Despite a relatively high incidence, there are few attempts at modelling impingement between the iliopsoas and acetabular component, and no attempts at modelling this in a representative cohort of subjects. The purpose of this study was to develop a novel computational model for quantifying the impingement between the iliopsoas and acetabular component and validate its utility in a case-controlled investigation.
METHODS: This was a retrospective cohort study of patients who underwent THA surgery that included 23 symptomatic patients diagnosed with iliopsoas tendonitis, and 23 patients not diagnosed with iliopsoas tendonitis. All patients received postoperative CT imaging, postoperative standing radiography, and had minimum six months\' follow-up. 3D models of each patient\'s prosthetic and bony anatomy were generated, landmarked, and simulated in a novel iliopsoas impingement detection model in supine and standing pelvic positions. Logistic regression models were implemented to determine if the probability of pain could be significantly predicted. Receiver operating characteristic curves were generated to determine the model\'s sensitivity, specificity, and area under the curve (AUC).
RESULTS: Highly significant differences between the symptomatic and asymptomatic cohorts were observed for iliopsoas impingement. Logistic regression models determined that the impingement values significantly predicted the probability of groin pain. The simulation had a sensitivity of 74%, specificity of 100%, and an AUC of 0.86.
CONCLUSIONS: We developed a computational model that can quantify iliopsoas impingement and verified its accuracy in a case-controlled investigation. This tool has the potential to be used preoperatively, to guide decisions about optimal cup placement, and postoperatively, to assist in the diagnosis of iliopsoas tendonitis.Cite this article: Bone Jt Open 2023;4(1):3-12.

UNASSIGNED: Iliopsoas impingement (IPI) is a known complication of total hip arthroplasty (THA). The aim of this study was to identify risk factors and the cut-off cup protrusion length for symptomatic IPI.
UNASSIGNED: We retrospectively reviewed 218 hips (46 men, 172 women) of 190 consecutive Japanese patients who underwent primary THA at our institution. Hips with IPI (n = 24) and control hips (n = 194) were compared according to age, body mass index, and clinical scores. We evaluated leg-length discrepancy, global offset, implant alignment angles, pelvic inclination, and anterior cup protrusion on plain radiographs and computed tomography scans.
UNASSIGNED: Symptomatic IPI had an incidence of 11.0% and a predilection for hips with osteonecrosis. Pre- and postoperative hip flexion angles were significantly greater in hips with symptomatic IPI (p = 0.013 and p = 0.006, respectively). Cup protrusion length was significantly greater in hips with IPI (4.7 mm vs. 1.4 mm; p = 0.001). Receiver-operating characteristic curve analysis identified a threshold cup protrusion length of 3.9 mm (sensitivity 0.89, specificity 0.63) for symptomatic IPI. The incidence of symptomatic IPI tended to be lower in patients with greater posterior pelvic sagittal inclination despite the cup protrusion length being greater.
UNASSIGNED: An increased hip flexion angle and protrusion of the anterior acetabular component predicted symptomatic IPI. The threshold cup protrusion length suggesting mild IPI might be about 3.9 mm and could be useful for identifying candidates for conservative treatment.