Improved accuracy of CT based measurements for anterior prominence of acetabular prosthesis using a novel protocol based on anatomical landmarks

Comparison of iliopsoas tendonitis after hip resurfacing arthroplasty and total hip arthroplasty: A case-controlled investigation using a validated simulation

Iliopsoas tendonitis, typically caused by impingement with the acetabular cup, occurs in up to 18% of patients after total hip arthroplasty (THA) and up to 30% of patients after hip resurfacing arthroplasty (HRA). We have developed a simulation for detecting iliopsoas impingement and validated it in a previous study of THA patients. However, due to the difference in incidence between HRA and THA, this study had two aims. First, to validate the simulation in a cohort of HRA patients and, second, to comparethe results of the HRA and THA patients to understand any differences in their etiology. We conducted a retrospective search in an experienced surgeon's database for HRA patients with iliopsoas tendonitisand control patients without iliopsoas tendonitis, resulting in two cohorts of 12 patients. Using CT scans, 3D models of the each patient's prosthetic and bony anatomy were generated, landmarked, and simulated. Regarding validation of the simulation for HRA patients, impingement significantly predicted the probability of iliopsoas tendonitis in logistic regression models and the simulation had a sensitivity of 83%, specificity of 100%, and an AUC ROC curve of 0.95. Unexpectedly, the HRA cohort exhibited less impingement than the THA cohort. Our novel simulation has now been demonstrated to detect iliopsoas impingement and differentiate between the symptomatic and asymptomatic cohorts in investigations of THA and HRA patients. 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.

What happens to endoscopic/arthroscopic tenotomies with iliopsoas impingement in the medium term? Review of a prospective cohort of 64 patients with a minimum follow-up of 5 years

INTRODUCTION

The occurrence of iliopsoas impingement (IPI) after total hip arthroplasty (THA) is a proven risk factor for negative outcomes. Endoscopic or arthroscopic tenotomies of the iliopsoas offer a surgical solution with short-term results that have already been validated in prospective multicenter series. We carried out a review of the patients at more than 5 years of follow-up in order to assess the stability of the results over time.

HYPOTHESIS

Our main hypothesis was that endoscopic/arthroscopic tenotomies allow stable medium-term resolution of the painful symptoms of IPI. Our secondary hypothesis was that medium-term survival was satisfactory.

MATERIAL AND METHOD

This study is a continuation of a multicenter prospective series. Patients were contacted through multiple channels in order to: obtain an Oxford score, assess for satisfaction, psoas irritation, and daily pain on a visual analogue scale (VAS).

RESULTS

Of 64 patients in the original study, 57 were contacted. The Oxford score at the last follow-up was 40.7±7.7 [12-48]. There was a significant difference between the Oxford scores preoperatively, at 8 months and at the last follow-up. The mean satisfaction out of 10 was 8.0±2.1 [1-10]. We found 84% satisfaction at 5 years against 83% at 8 months. The VAS was 2.1±2.3 [0-10]. A straight leg psoas sign was present in 19.6% (10/51) of patients at 5 years, compared to 15.6% (8/51) at 8 months. The sign disappeared in four cases, while it reappeared during the interval in six cases. Survival was 91.2% (95% CI: 80.2-96.3) at 5 years.

CONCLUSION

Endoscopic/arthroscopic iliopsoas tenotomies represent a permanent medium-term solution to treat IPI after THA. The existence of a force differential or an acetabular overhang does not seem, within a certain limit, to impact the results in the medium term.

LEVEL OF EVIDENCE

IV; prospective series without control group.

What happens in the medium-term to capsule-thickening plasties for iliopsoas impingement after total hip arthroplasty? Evaluation of 14 procedures at 4years' follow-up

INTRODUCTION

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.

HYPOTHESIS

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.

MATERIAL AND METHOD

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).

CONCLUSION

This surgical option seems interesting when acetabular overhang is not too great, especially as it does not affect flexion strength.

LEVEL OF EVIDENCE

IV.

Cup Overhanging in Anatomic Socket Position or High Hip Center of Rotation in Total Hip Arthroplasty for Crowe III and IV Dysplasia: A CT-Based Simulation

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.

Iliopsoas tendonitis after total hip arthroplasty : an improved detection method with applications to preoperative planning

AIMS

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.

CONCLUSION

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.

The accuracy and precision of acetabular implant measurements from CT imaging

The placement of acetabular implant components determines the short- and long-term outcomes of total hip replacement (THR) and a number of tools have been developed to assist the surgeon in achieving cup orientation to match the surgical plan. However, the accuracy and precision of 3D-CT for the measurement of acetabular component position and orientation is yet to be established. To investigate this, we compared measurements of cobalt chrome acetabular components implanted into 2 different bony pelvic models between a coordinate measuring Faro arm and 3 different low dose CT images, including 3D-CT, 2D anterior pelvic plane (APP) referenced CT and 2D scanner referenced (SR) CT. Intra-observer differences were assessed using the Intraclass correlation coefficient (ICC). The effect of imaging the pelvis positioned in 3 different orientations within the CT scanner was also assessed. The measured parameters were the angles of inclination and version. 3D-CT measurements were found to closely match the "true values" of the component position measurements, compared with the 2D-CT methods. ICC analysis also showed good agreement between the coordinate measuring arm (CMA) and 3D-CT but poor agreement between the 2D SR method, in the results from two observers. When using the coordinate system of the CT scanner, the measurements consistently produced the greatest error; this method yielded values up to 34° different from the reference digitising arm. However, the difference between the true inclination and version angles and those measured from 3D APP CT was below half a degree in all cases. We concluded that low radiation dose 3D-CT is a validated reference standard for the measurement of acetabular cup orientation.

Endoscopic Tenotomy for Iliopsoas Tendinopathy Following Total Hip Arthroplasty Can Relieve Pain Regardless of Acetabular Cup Overhang or Anteversion

PURPOSE

To report outcomes of endoscopic iliopsoas tenotomy (EIT) in patients with iliopsoas tendinopathy following total hip arthroplasty (THA) and determine whether improvements in clinical scores are associated with acetabular cup anteversion measured on plain radiographs or overhang measured using established and alternative computed tomography (CT)-based methods.

METHODS

We evaluated patients who underwent EIT for iliopsoas tendinopathy after THA (2014-2017), performed between the lesser trochanter and psoas valley. Indications were groin pain during active hip flexion, exclusion of other complications, and no pain relief after 6 months of conservative treatment. Pretenotomy inclination and anteversion were measured on radiographs; sagittal and axial overhang were measured on CT scans on slices passing through: (Method 1) prosthetic head center and (Method 2) anterior margin of acetabular cup. Modified Harris hip score (mHHS), Oxford Hip Score (OHS), and level of groin pain were recorded at 12 or more months. Wilcoxon signed-rank tests were used to compare pre- and post-tenotomy scores, and intraclass correlation coefficients (ICCs) to assess intermethod agreement.

RESULTS

The cohort comprised 16 men (17 hips) and 32 women (33 hips), aged 60.8 ± 10.5 years at EIT. For the 30 (60%) hips that had pretenotomy CT scans, axial and sagittal overhang were, respectively, 3.4 ± 3.7 mm and 4.6 ± 4.6 mm, using Method 1, compared with 3.9 ± 3.9 mm and 6.9 ± 5.0 mm using Method 2. Intermethod agreement was good for axial (ICC, 0.67; P < .001) and sagittal (ICC, 0.68; P < .001) overhang. At a minimum 1 year after EIT, 3 hips had cup and stem revision and 1 hip had isolated cup revision, leaving 46 hips for clinical assessment. No complications were noted. mHHS improved by 26 ± 19 (P < .001) and OHS improved by 20 ± 11 (P < .001). Twenty-six hips (57%) achieved the patient acceptable symptom state for mHHS, whereas 42 hips (91%) achieved the patient acceptable symptom state for OHS. Post-tenotomy groin pain was slight in 15%, mild in 17%, and moderate in 11%. Regression analyses revealed no associations between clinical scores and overhang/anteversion.

CONCLUSIONS

For patients with iliopsoas tendinopathy following THA, endoscopic iliopsoas tenotomy granted clinically important improvements of mHHS in 76% and OHS in 89%, despite moderate residual groin pain in 11%. Improvements in clinical scores did not seem to be associated with the extent of cup overhang or anteversion in the cases for which adequate preoperative imaging was available.

LEVEL OF EVIDENCE

Level IV, retrospective cohort study.