RPS 1010b - Hip, pelvis and lower extremity

Purpose:

In paediatric orthopaedics, the use of potentially harmful CT could be avoided by generating synthetic CT (sCT) from radiation-free MR images. Although widely investigated for radiotherapy, sCTs have not been evaluated for orthopaedics. In this study, we compared clinically relevant measurements for hip dysplasia as performed on CTs and sCTs.

Methods and materials:

30 male prostate cancer patients without known orthopaedic conditions were included and scanned with MR and CT for radiotherapy treatment planning. Morphological assessment of the femoroacetabular joint was performed on CT and sCT reconstructions obtained from a BoneMRI prototype (BoneMRI v1.1-alpha, MRIguidance BV, Utrecht, the Netherlands). Clinical measurements for evaluation included centre-edge angle (CEA), sharp angle (SA), extrusion index (EI), acetabular index (AcetIncl), and femoral centre-to-midline distance (FCMD). Equivalence was tested for each measurement using a paired two-one sided test. The equivalency margins were defined using literature values of the intraobserver limit of agreement measured on x-ray. CT and sCT were considered equivalent for confidence intervals of the mean difference between the CT and the sCT within ±4.2° for CEA, ±5.6° for AcetIncl, ±2.9° for SA, ±6.1% for EI, and ±4.5 mm for FCMD.

Results:

All measurements were proven equivalent between the CT and sCT. Bonferonni-corrected confidence intervals at 95% were -2.0° and 0.9° for the CEA, 0.3° and 1.4° for SA, -2.4% and 1.0% for EI, -1.5° and 0.9° for the AcetIncl, and 0 mm and 0.6 mm for FCMD. No patient presented a substantial difference for all measurements.

Conclusion:

This study demonstrates that sCT is equivalent with CT for femoroacetabular morphological assessment in adults.

Limitations:

Future studies are necessary to confirm these findings in paediatric patients.

Ethics committee approval

Medical-ethical approval was obtained.

Funding:

Dutch Scientific Organisation NWO-TTW-15479.

Purpose:

The segmentation of psoas muscles at L3 is used to estimate sarcopenia status. However, this parameter is not useful when CT is performed in other districts. Our aim was to correlate the estimation of muscle mass around the hip with that obtained using psoas segmentation at L3 on CT.

Methods and materials:

A radiologist reviewed abdominal CTs performed on 50 consecutive patients (29 males; mean age: 69.6±11y). Regions of interest were drawn to assess cross-sectional areas (CSA) and attenuation of psoas muscles at the L3 level, which was considered as the standard. These values were correlated with CSA and attenuation of the iliopsoas, rectus femoris, sartorius, and tensor fascia latae at the hip, separately on each side. After applying the Bonferroni correction for multiple comparisons, statistical significance was set as P<0.002.

Results:

We found a significant correlation between attenuation values of both psoae at L3 and those of all the other hip muscles (P<0.001, r>0.491). A significant correlation was observed between CSA of the right psoas and the other muscles (P≤0.001, r>0.459), except for the tensor fascia latae at the lesser trochanter (P=0.004, r=0.401). We observed a significant correlation between CSA of the left psoas at L3 and that of the psoas and rectus femoris at the hip (P=0.001, r=0.456), with no significant correlation with tensor fascia latae and sartorius (P≥0.002, r≤0.430).

Conclusion:

CT segmentation of hip muscles is highly correlated to that performed on the psoas at the L3 level, except for tensor fascia latae. These measurements could be used to evaluate sarcopenia in patients undergoing hip surgery.

Limitations:

A small population.

Ethics committee approval

n/a

Funding:

No funding was received for this work.

Purpose:

Magnetic resonance imaging is often employed as the diagnostic modality of choice in occult and suspected pathological femoral neck fractures. The research question is: does the use of an MRI scan in occult and suspected metastatic pathological neck of femur fractures affect the choice of surgical intervention?

Methods and materials:

A retrospective observational analysis was conducted of 104 consecutive patients who had an MRI scan of the hip from July 2009-August 2011 among a total population of 894 hip fractures managed in our institution. The findings of plain radiography, which preceded MRI, were recorded. The data was extracted from the medical records and an online image archiving system. Statistical analysis software SAS/STAT^® SAS Institute Inc. USA^© was used to conduct data collation and analyses.

Results:

From a total of 894 femoral neck fractures treated in our institution, 100 patients had an MRI scan preoperatively for either an occult fracture or suspected fracture secondary to metastatic disease. MRIs confirmed the presence of 13 simple fractures. A total of 14 patients had pathological features suggestive of metastasis, of which 12 were clearly visible on plain radiographs. The surgical plan did not change after MRI for any of these pathological fractures.

Conclusion:

Results of this study demonstrate that an MRI scan had an impact on treatment selection only when a simple but radiographically occult fracture is suspected, but not in the context of suspected metastatic pathological fractures.

Limitations:

n/a

Ethics committee approval

Institutional agreement was obtained before the study. Ethics committee approval was not required to carry out this study.

Funding:

No funding was received for this work.

Purpose:

To review iliopsoas impingement after a total hip replacement (THR) and the usefulness of US-guided infiltration as a diagnostic technique, to assess the effectiveness of the different treatment modalities for this condition, and to establish a relation between CT position parameters of the prosthesis and clinical response.

Methods and materials:

This retrospective study from 2017-2019 included 35 patients (20 female; mean age 66.7 years; mean BWI 26.6) who underwent total hip replacement (60% right hip; 74.3% posterolateral surgical approach) at our institution. The mean time of pain appearance after THR was 11.1 months.

All patients had a positive test to anaesthesia and glucocorticoid US-guided infiltration of the iliopsoas tendon sheath. When pain recurrence appeared, endoscopic tenotomy was performed.

Inclination, corrected anteversion, medialisation, and axial and sagittal acetabular overhanging of the prothesis were measured on CT.

Therapeutic efficacy was evaluated by VAS and Harris score pre and post-treatment.

Results:

67% of the patients had a delayed pain recurrence after infiltration, which did not correlate with prothesis position CT parameters.

From the patients who underwent endoscopic tenotomy (n=13), the majority (n=8) had a total or partial positive clinical outcome.

High degrees of horizontal and vertical overhanging (>10 mm) correlated significantly with a negative response to treatment (p<0.05). So, CT parameters can help in clinical management decision (tenotomy vs acetabular change).

Conclusion:

A US-guided anaesthesia and glucocorticoid infiltration test is a useful tool in iliopsoas impingement diagnosis and conservative treatment.

Endoscopic tenotomy will produce remission of pain in most of the patients. Nevertheless, an acetabular cup overhanging of >10 mm is a negative prognostic factor to surgical treatment response.

Limitations:

n/a

Ethics committee approval

n/a

Funding:

No funding was received for this work.

Purpose:

Diagnosis and surgical treatment of hips with different types of pincer-FAI, such as protrusio acetabuli and acetabular retroversion, remains controversial as actual 3D acetabular coverage and location of impingement cannot be studied using standard 2D imaging. It remains unclear if pincer hips exhibit intra- or extra-articular FAI. Therefore, the purposes are to determine the impingement-free range of motion using osseous models based on 3D-CT scans and to determine the osseous intra-and extra-articular 3D impingement zones located using a 3D impingement simulation.

Methods and materials:

This is a retrospective, comparative, controlled study involving 70 hips in 50 patients. 24 patients (44 hips) had symptomatic pincer-type FAI and 26 patients (26 hips) had normal hips. Surface models based on 3D-CT scans were reconstructed and compared for hips with acetabular retroversion (30 hips), protrusio acetabuli (14 hips), and normal asymptomatic hips (26 hips). Using CT-based 3D-models, impingement-free ROM and location of impingement were determined for all hips using validated 3D-collision detection software.

Results:

The mean flexion was significantly (p<0.001) decreased in hips with protrusio acetabuli (104±9°) and acetabular retroversion (116±6°) compared to normal hips (125±13°). The mean internal rotation (IR) in 90° of flexion was significantly (p<0.001) decreased in hips with protrusio acetabuli (14±11°) compared to normal hips (32±9°).

The prevalence of extra-articular subspine impingement was significantly (p<0.001) higher (87%) in hips with acetabular retroversion compared to hips with protrusio acetabuli (14%) and normal hips (0%). The location of anterior acetabular impingement differed significantly (p<0.001) between hips with protrusio acetabuli and normal hips.

Conclusion:

Extra-articular subspine impingement was detected in hips with acetabular retroversion. Osseous ROM and location of impingement differs between hips with protrusio acetabuli, acetabular retroversion, and normal hips. Patient-specific analysis of the location of impingement using 3D-CT could improve diagnosis and planning of treatment.

Limitations:

A retrospective, single-centre study.

Ethics committee approval

IRB approval was obtained.

Funding:

No funding was received for this work.

Purpose:

To validate a physical examination test for ischiofemoral (IF) impingement and correlate MRI findings.

Methods and materials:

The population of this prospective study comprised of a symptomatic group of 24 women with hip pain, who had positive MRI findings (IF space narrowing and oedema), and an age-matched group of 27 asymptomatic women. Each group underwent a physical examination test that entailed hip adduction, external rotation, extension, and knee flexion, both in the recumbent and upright standing positions, within 7 days of an MRI. VAS scores were noted before and after the test. A single radiologist quantitatively and qualitatively evaluated the IF and quadratus femoris (QF) spaces on 1.5T MR images.

Results:

Mean ages were 56.0 (34-76) and 55.2 (34-79) years in symptomatic and asymptomatic groups, respectively (p>0.05). Likewise, BMIs were not statistically significantly different between the groups. IF and QF spaces were significantly narrower (p<0.001), ischial angles wider (p<0.001, right; p=0.002, left), and soft tissue oedema at the IF space was more common (p<0.001) in the symptomatic group, which also had higher VAS scores (p<0.001) that increased significantly during both the recumbent (p<0.001 for both sides) and upright (p=0.003, right; p<0.001, left) parts of the physical examination test.

Conclusion:

A physical examination test that entails hip adduction, external rotation, extension, and knee flexion significantly increases symptoms of IF impingement that are correlated on MRI.

Limitations:

A small number of patients. A single radiologist performing MRI evaluation.

Ethics committee approval

We obtained institutional review board approval and informed consent.

Funding:

No funding was received for this work.