Patterns of joint damage seen on MRI in early hip osteoarthritis due to structural hip deformities

Porcine computational modeling to investigate developmental dysplasia of the hip

While it is well-established that early detection and initiation of treatment of developmental dysplasia of the hip (DDH) is crucial to successful clinical outcomes, research on the mechanics of the hip joint during healthy and pathological hip development in infants is limited. Quantification of mechanical behavior in both the healthy and dysplastic developing joints may provide insight into the causes of DDH and facilitate innovation in treatment options. In this study, subject-specific three-dimensional finite element models of two pigs were developed: one healthy pig and one pig with induced dysplasia in the right hindlimb. The objectives of this study were: (1) to characterize mechanical behavior in the acetabular articular cartilage during a normal walking cycle by analyzing six metrics: contact pressure, contact area, strain energy density, von Mises stress, principal stress, and principal strain; and (2) to quantify the effect on joint mechanics of three anatomic abnormalities previously identified as related to DDH: variation in acetabular coverage, morphological changes in the femoral head, and changes in the articular cartilage. All metrics, except the contact area, were elevated in the dysplastic joint. Morphological changes in the femoral head were determined to be the most significant factors in elevating contact pressure in the articular cartilage, while the effects of acetabular coverage and changes in the articular cartilage were less significant. The quantification of the pathomechanics of DDH in this study can help identify key mechanical factors that restore normal hip development and can lead to mechanics-driven treatment options.

Does the dGEMRIC Index Recover 3 Years After Surgical FAI Correction and an Initial dGEMRIC Decrease at 1-Year Follow-up? A Controlled Prospective Study

BACKGROUND

Delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC) allows objective and noninvasive assessment of cartilage quality. An interim analysis 1 year after correction of femoroacetabular impingement (FAI) previously showed that the dGEMRIC index decreased despite good clinical outcome.

PURPOSE

To evaluate dGEMRIC indices longitudinally in patients who underwent FAI correction and in a control group undergoing nonoperative treatment for FAI.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

This prospective, comparative longitudinal study included 39 patients (40 hips) who received either operative (n = 20 hips) or nonoperative (n = 20 hips) treatment. Baseline demographic characteristics and presence of osseous deformities did not differ between groups. All patients received indirect magnetic resonance arthrography at 3 time points (baseline, 1 and 3 years of follow-up). The 3-dimensional cartilage models were created using a custom-developed deep learning-based software. The dGEMRIC indices were determined separately for acetabular and femoral cartilage. A mixed-effects model was used for statistical analysis in repeated measures.

RESULTS

The operative group showed an initial (preoperative to 1-year follow-up) decrease of dGEMRIC indices: acetabular from 512 ± 174 to 392 ± 123 ms and femoral from 530 ± 173 to 411 ± 117 ms (both P < .001). From 1-year to 3-year follow-up, dGEMRIC indices improved again: acetabular from 392 ± 123 to 456 ± 163 ms and femoral from 411 ± 117 to 477 ± 169 ms (both P < .001). The nonoperative group showed no significant changes in dGEMRIC indices in acetabular and femoral cartilage from baseline to either follow-up point (all P > .05).

CONCLUSION

This study showed that 3 years after FAI correction, the dGEMRIC indices improved compared with short-term 1-year follow-up. This may be due to normalized joint biomechanics or regressive postoperative activation of the inflammatory cascade after intra-articular surgery.

Acetabular paralabral cysts demonstrating perineural propagation

OBJECTIVE

Acetabular paralabral cysts are common and are almost always associated with labral tears. Uncommonly, they extend into the periacetabular soft tissues or may propagate along peripheral nerves causing pain and hip dysfunction. The aim was to evaluate the clinical and MRI presentations of such cases including perineural propagation.

METHODS

Retrospective cross-sectional study with a search of electronic health records for cases of acetabular paralabral cysts demonstrating perineural propagation was performed. Clinical and MR imaging features were tabulated after re-review by experienced musculoskeletal radiologists, and available outcomes were recorded. Descriptive statistics were performed.

RESULTS

14 cases were recorded. The mean age was 56.9 years (range = 30-79 years) and female:male ratio was 1:2.6. The commonest presenting complaint was hip pain (10/14, 71.4%). Other complaints included groin pain, perineal pain and hip dysfunction. No symptoms were attributed to the acetabular paralabral cyst in 3/14 patients (21.4%). None had foot drop. The cysts were multilocular in all cases and were homogenously T2 hyperintense in 13/14 (92.9%). Labral tears were identified in 11/14 cases (78.6%). The sciatic nerve was most commonly involved in 5/14 cases (35.7%) with the obturator, medial femoral cutaneous nerve, femoral nerve, superior and inferior gluteal nerves also affected.No intervention was undertaken in 9/14 cases (64.3%). 5/14 (35.7%) underwent image guided aspiration and corticosteroid injection. 4/5 such patients reported reduced pain following the procedure.

CONCLUSION

Paralabral cysts demonstrating perineural propagation are uncommon and exhibit varied presentations. Most patients who underwent image-guided or surgical interventions reported an improvement in symptoms.

ADVANCES IN KNOWLEDGE.

This is the first description of a series of patients with acetabular paralabral cysts demonstrating perineural propagation in the literature. A comprehensive description of their clinical and imaging characteristics and interventions/outcomes where relevant is provided.

Acellular Matrix-Induced Chondrogenesis Technique Improves the Results of Chondral Lesions Associated With Femoroacetabular Impingement

PURPOSE

The study's main objective was to evaluate, in the short-term, the result of the autologous acellular matrix-induced chondrogenesis (AMIC) technique in a selected group of patients with 2-4 cm² full-thickness chondral lesions, undergoing hip arthroscopy for femoroacetabular impingement (FAI).

METHODS

A retrospective single-center Level IV case series of 25 patients (28 hips) who underwent an arthroscopic hip surgery with a liquid acellular collagen matrix. Inclusion criteria for implantation were FAI diagnosis (cam or pincer type), grade IV chondral lesions (Outerbridge size 2-4 cm²); Tönnis stage 0-II, minimum follow-up of 24 months, and 1 year (12-15 months) evaluation with very high field 3-T MRI arthrography. Exclusion criteria were Tönnis III, joint space <2 mm, center-edge angle <20°, and <24 months of follow-up. Clinical assessments involved symptoms duration until surgery, changes in physical and work activity and range of motion, modified Harris Hip Score, reporting percentages of patient acceptable symptomatic state (PASS) and minimal clinically important difference (MCID), pain with a VAS, and level of satisfaction. Radiological assessments: Tönnis stage, articular space, alpha and lateral center edge angle (Wiberg), and generated tissue characteristics at 1 year (based on the MOCART score), through 3-T MRI.

RESULTS

25 patients (28 hips) treated; 19 men and 6 women (mean age: 40.5 years; range: 25-55). Two women underwent joint replacement surgery. Thus, 23 patients (26 hips) were analyzed. At 29 months following surgery (range: 24-48), a significant improvement was obtained in all parameters assessed, focusing on the characteristics of the generated tissue in the MRI (MOCART scores). 95% of the patients met the MCID (improvement >12 points in the modified Harris Hip Score), and 100% scored >74 points, achieving the PASS. Patients' satisfaction was 86.6% (SD 16.4). All patients who practiced sports resumed them.

CONCLUSIONS

The liquid AMIC is a safe technique that shows good clinical and radiological outcomes in a 2-year follow-up in patients with femoroacetabular impingement and grade IV acetabular 2-4 cm² chondral defects.

LEVEL OF EVIDENCE

Level IV, retrospective case series.

[Imaging in joint-preserving hip surgery]

Instabilität und Impingement stellen die Hauptpathomechanismen dar, die bereits bei jungen Patienten durch erhöhten mechanischen Stress zu chondrolabralen Schäden, schmerzhafter Bewegungseinschränkung und frühzeitiger Coxarthrose führen können. Ziele der gelenkerhaltenden Chirurgie an der Hüfte sind die Korrektur der knöchernen Deformitäten und chondrolabraler Schäden sowie die Wiederherstellung der Gelenkfunktion. Voraussetzung dafür ist die Identifikation der ursächlichen Pathologien an der Hüfte, welche zudem in Kombination auftreten können. Die dezidierte Röntgen- und Magnetresonanzbildgebung der knöchernen Morphologie und der degenerativen Gelenkbinnenläsionen liefern einen essenziellen Beitrag für die Behandlungsindikation und die Behandlungsplanung. Der vorliegende Artikel soll einen kurzen Überblick über die Hüftdeformitäten mit deren Prävalenz, Pathomechanismus und indizierter Therapie sowie detaillierte Empfehlungen über die spezifische radiologische Abklärung geben.

Residual acetabular dysplasia in congenital hip dysplasia

Residual hip dysplasia may exist despite appropriate treatment of congenital hip dysplasia (CHD). The abnormalities chiefly affect the acetabulum and can lead to premature osteoarthritis. Although the main cause is delayed treatment of CHD, primary lesions are also possible and may be worsened by the initial treatment itself. Residual hip dysplasia must be detected during the follow-up of patients with CHD. The antero-posterior radiograph of the pelvis is the main diagnostic tool. However, the importance of non-ossified anatomical structures requires additional investigations such as arthrography and magnetic resonance imaging. The risk of premature osteoarthritis is difficult to predict based only on the imaging-study findings. Hip dysplasia is best treated before 5 years of age. The work-up at this age should allow determination of the best treatment. Surgery is required but should not be performed unnecessarily. The decision rests on the absence of improvement in the radiographic criteria and on the findings from additional imaging studies. The usual treatment is Salter's osteotomy, during which excessive anterior displacement should be avoided. At adolescence, the information provided by radiography in the coronal plane should be completed by a three-dimensional evaluation of the acetabulum and an assessment of the quality of the labrum. The shelf procedure has been proven to relieve pain and to significantly postpone the need for hip arthroplasty, when performed early, before the development of visible osteoarthritis, and on a congruent hip. Chiari's osteotomy has a role to play in complex dysplasia affecting both the acetabulum and the femur. Periacetabular osteotomy is getting more used thanks to cooperation between paediatric and adult orthopaedic surgeons. This osteotomy provides optimal correction in all three dimensions.

Nonarthritic Hip Pathology Patterns According to Sex, Femoroacetabular Impingement Morphology, and Generalized Ligamentous Laxity

BACKGROUND

Sex differences are frequently encountered when diagnosing orthopaedic problems. Current literature suggests specific sex differences, such as a higher prevalence of cam-type femoroacetabular impingement syndrome in male patients and features of hip instability in female patients.

PURPOSE

To identify hip pathology patterns according to sex, alpha angle deformity, and generalized ligamentous laxity (GLL) in a nonarthritic patient population that underwent primary hip arthroscopy in the setting of femoroacetabular impingement syndrome and labral tears.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

Patients who underwent primary hip arthroscopy between February 2008 and February 2017 were included and separated into male and female groups for initial analysis. Patients were excluded if they had Tönnis osteoarthritis grade >1, previous ipsilateral hip surgery, or previous hip conditions. The demographics, radiographic findings, intraoperative findings, and surgical procedures were then analyzed and compared. Subanalyses were performed for both groups. A threshold of 1 SD above the mean alpha angle in the male group was used to create 2 subgroups. For female patients, GLL based on a Beighton score ≥4 was used to divide the group. Intraoperative findings were compared for both subanalyses.

RESULTS

A total of 2701 hips met all inclusion and exclusion criteria. Of those, 994 hips were in the male group and 1707 in the female group. The mean ± SD age was 36.6 ± 13.8 and 37.1 ± 15.0 years for the male and female groups, respectively(P = .6288). The average body mass index was significantly higher in the male group (P < .0001). GLL was more common in women (38.6%) than men (13.6%) (P < .001). The male group had a higher proportion of acetabular Outerbridge grade 3 (21.8%) and 4 (19.2%) lesions when compared with the female group (9.3% and 6.3%, respectively) (P < .0001). Men in the subgroup with an alpha angle ≥78° reported higher rates of acetabular Outerbridge grade 4 damage than men with an alpha angle <78° (P < .001). Mean lateral center-edge angle was lower in the female subgroup with Beighton score ≥4 vs <4 (23.7°± 4.2° vs 31.3°± 5.8°; P < .0001).

CONCLUSION

In this analysis of a large cohort of patients who underwent hip arthroscopy, 2 patterns of hip pathologies were related to sex. On average, male patients had larger alpha angles and increased acetabular chondral damage when compared with their female counterparts. Furthermore, a larger cam-type anatomy was associated with more severe acetabular chondral damage in men. In the female group, the incidence of features of hip instability such as GLL were significantly higher than in the male group.

Improved Cartilage Quality on Delayed Gadolinium-Enhanced MRI of Hip Cartilage after Subchondral Drilling of Acetabular Cartilage Flaps in Femoroacetabular Impingement Surgery at Minimum 5-Year Follow-Up

OBJECTIVE

To assess whether subchondral drilling of acetabular cartilage flaps during femoroacetabular impingement (FAI) surgery improves (1) acetabular dGEMRIC indices and (2) morphologic magnetic resonance imaging (MRI) scores, compared with hips in which no additional treatment of cartilage lesions had been performed; and (3) whether global dGEMRIC indices and MRI scores correlate.

DESIGN

Prospective cohort study of consecutive patients with symptomatic FAI treated with open surgery between 2000 and 2007. Patients with subchondral drilling of acetabular cartilage flaps were allocated to the study group, those without drilling to the control group. All patients underwent indirect 3-T MR arthrography to assess cartilage quality by dGEMRIC indices and a semiquantitative morphologic MRI score at minimum 5 years after surgery. dGEMRIC indices and morphologic MRI scores were compared between and among groups using analysis of covariance/paired t tests.

RESULTS

No significant difference was found between the global dGEMRIC indices of the study group (449 ± 147 ms, 95% CI 432-466 ms) and the control group (428 ± 143 ms, 95% CI 416-442 ms; P = 0.235). In regions with cartilage flaps, the study group showed higher dGEMRIC indices (472 ± 160 ms, 95% CI 433-510 ms) compared with the control group (390 ± 122 ms, 95% CI 367-413 ms; P < 0.001). No significant differences were found for the morphologic MRI scores. A strong inversely linear correlation between the dGEMRIC indices and the morphologic MRI scores (r = -0.727, P < 0.001) was observed.

CONCLUSIONS

Treatment of acetabular cartilage flaps with subchondral drilling leads to better cartilage quality in regions with cartilage flaps at minimum 5 years of follow-up.

The role and clinical relevance of the ligamentum teres: long-term outcomes after hip arthroscopic surgery of cam-type femoroacetabular impingement

We aimed to compare clinical and radiologic outcomes in patients with cam-type femoroacetabular impingement (FAI), with and without a partial ligamentum teres (LT) tear, who underwent hip arthroscopy (HA) with ≥10 years of follow-up. Among the patients who underwent HA for a cam-type FAI diagnosis with a labral tear, 28 patients (28 hips) with a partial LT tear and 87 patients (99 hips) with an intact LT were assigned to Groups A and B, respectively. All patients underwent partial labral debridement and femoroplasty. Debridement and thermal shrinkage were performed for LT tears. The grade of chondral damage was measured intraoperatively. Clinical items were assessed preoperatively and at the last follow-up. Patients’ satisfaction with the surgery and changes in postoperative sports ability in those who had previously been active in sports were assessed at the last follow-up. The Tönnis grade was assessed preoperatively and at the last follow-up for radiologic evaluation. Chondral damage to the acetabular and femoral head detected intraoperatively was significantly different between the groups (P = 0.005 and P &lt; 0.001). At the last follow-up, Group A patients experienced more difficulty performing sports activities than Group B patients (P = 0.056), and significantly, more Group A patients had stopped exercising despite their active participation in sports preoperatively (P = 0.002). Regarding the Tönnis grade, significant differences were found only at the final follow-up (P = 0.020). Patients with partial LT tear showed a higher grade of chondral damage, experienced decreased exercise capacity and had significantly worsened Tönnis grades, suggesting hip osteoarthritis progression compared to those with an intact LT.

Intraoperative Computer Vision Integrated Interactive Fluoroscopy Correlates With Successful Femoroplasty on Clinic-Based Radiographs

PURPOSE

To quantitatively evaluate computer vision interface (CVI)-guided femoroplasty in the arthroscopic treatment of femoroacetabular impingement syndrome and compare those results with traditional unguided resections.

METHODS

Consecutive patients undergoing hip arthroscopy for femoroacetabular impingement syndrome between July 2019 and October 2019 were evaluated. Cases with CVI were identified along with controls, consisting of patients from the same study period who underwent surgery without the CVI and were balanced for age, sex, laterality, and preoperative alpha angles. Alpha angles were measured on pre- and postoperative clinic radiographs, as well as intraoperatively for the CVI group. Cam resections were quantified by measuring pre- and postresection alpha angles and compared between groups. The correlation between CVI views and office-based radiographs was assessed, and the 3 CVI views that best correlated with each of the 3 standard clinic radiographs were evaluated for accuracy and performance in detection of cam deformity with alpha angle ≥48° with the clinic-based films as the reference.

RESULTS

A total of 49 patients (51 hips) (average age, 28.7; 33 female patients) in the CVI group, and 51 patients (51 hips) (average age: 29.9; 35 female patients) in the control group. There were no significant differences between groups with respect to age, sex, laterality, or preoperative alpha angle (all P > .05). Significant alpha angle reduction occurred on all intraoperative and postoperative clinic views (all P < .01). The CVI views that best correlated with the clinic radiographs were 11:45 with the anteroposterior (ρ = 0.588, P = .0025), 12:30 with the Dunn lateral (ρ = 0.632, P = .0009), and 1:45 with the false-profile (ρ = 0.575, P = .0033). Greater reliability was observed with 12:30/Dunn (accuracy = 83.33%, P < .0001; sensitivity = 77.14%; specificity = 87.76%) and 1:45/false-profile (accuracy = 82.35%, P = .0051; sensitivity = 81.82%; specificity = 82.61%) than with 11:45/anteroposterior (accuracy = 69.15%, P = .0077; sensitivity = 56.10%; specificity = 79.25%).

CONCLUSIONS

CVI-guided cam resection results in successful resection of proximal femur cam lesions and represents a femoroplasty templating method that does not require preoperative computed tomography imaging or additional invasive intraoperative referencing modules. The accuracy and adequacy of this resection was validated by comparison with routine clinic radiographs.

LEVEL OF EVIDENCE

Therapeutic Level III: retrospective comparative analysis.

Machine learning identifies factors related to early joint space narrowing in dysplastic and non-dysplastic hips

OBJECTIVES

To utilise machine learning, unsupervised clustering and multivariate modelling in order to predict severe early joint space narrowing (JSN) from anatomical hip parameters while identifying factors related to joint space width (JSW) in dysplastic and non-dysplastic hips.

METHODS

A total of 507 hip CT examinations of patients 20-55 years old were retrospectively examined, and JSW, center-edge (CE) angle, alpha angle, anterior acetabular sector angle (AASA), and neck-shaft angle (NSA) were recorded. Dysplasia and severe JSN were defined with CE angle < 25^o and JSW< 2 mm, respectively. A random forest classifier was developed to predict severe JSN based on anatomical and demographical data. Multivariate linear regression and two-step unsupervised clustering were performed to identify factors linked to JSW.

RESULTS

In dysplastic hips, lateral or anterior undercoverage alone was not correlated to JSN. AASA (p < 0.005) and CE angle (p < 0.032) were the only factors significantly correlated with JSN in dysplastic hips. In non-dysplastic hips, JSW was inversely correlated to CE angle, AASA, and age and positively correlated to NSA (p < 0.001). A random forest classifier predicted severe JSN (AUC 69.9%, 95%CI 47.9-91.8%). TwoStep cluster modelling identified two distinct patient clusters one with low and one with normal JSW and different anatomical characteristics.

CONCLUSION

Machine learning predicted severe JSN and identified population characteristics related to normal and abnormal joint space width. Dysplasia in one plane was found to be insufficient to cause JSN, highlighting the need for hip anatomy assessment on multiple planes.

KEY POINTS

• Neither anterior nor lateral acetabular dysplasia was sufficient to independently reduce joint space width in a multivariate linear regression model of dysplastic hips. • A random forest classifier was developed based on measurements and demographic parameters from 507 hip joints, achieving an area under the curve of 69.9% in the external validation set, in predicting severe joint space narrowing based on anatomical hip parameters and age. • Unsupervised TwoStep cluster analysis revealed two distinct population groups, one with low and one with normal joint space width, characterised by differences in hip morphology.

Survival Analysis of Total Hip Arthroplasty for High Hip Dislocation Secondary to Developmental Dysplasia or Septic Arthritis of the Hip

BACKGROUND

This retrospective study was conducted to know clinical and radiographic outcomes, complication rate, and survival of THA in patients with high hip dislocation secondary to developmental dysplasia(DDH) or septic arthritis of the hip(SSH).

METHODS

Between March 2005 and September 2014, there were consecutive series of 53 THAs in patients with a highly dislocated hip secondary to DDH or SSH. Of these, 48 hips (DDH 24 and SSH 24) were reviewed at a mean follow-up of 7.9 years(range, 5.0-14.3 years). The mean age at the time of THA was 39.1 years(range, 18.0-59.0 years).

RESULTS

Intraoperative blood loss, total drainage and blood transfusion amounts, and mean time to greater trochanter union were significantly lower in the DDH group than in the SSH group (P = .001, P = .039 and P = .014, and P = .015, respectively). No significant difference in Kaplan-Meier survivorship was observed between groups (log-rank, P = .343). The survival rates with an endpoint of cup aseptic loosening in cases with a cemented cup at 7.9 and 10 years (68.1% and 60.5%, respectively) were significantly lower than those in cementless cup cases (100%) at the same checkpoints (P = .019)..

CONCLUSION

We found similar clinical outcomes between the DDH and SSH groups. However, due to poor bone quality and a lack of containment, cementless acetabular cups could not be performed in more than 50% of patients. Our experience shows that revision cementless fixation cup was possible due to reconstitution of the acetabulum in cases with failed cemented fixation.

Secreted frizzled-related protein 3 was genetically and functionally associated with developmental dysplasia of the hip

Background: Developmental dysplasia of the hip (DDH) is the most common joint disease in child orthopedics. Secreted Frizzled-Related Protein 3 (FRZB) plays an important role in joint development. however, no direct association between FRZB and DDH has been demonstrated.

Methods: Analysis of genotype distribution and allele frequency for detected single nucleotide polymorphisms (SNP) of FRZB was performed. FRZB expression was assayed in DDH joint tissues. Further experiments to identify the chondrogenic properties of FRZB were conducted. Potential upstream miRNAs for FRZB were assayed in DDH.

Results: Significant difference in genotype distribution for rs3768842 (OR=1.46, P=0.0081) and rs2242040 (OR=0.65, P=0.0067) was found. DDH joint tissues showed significantly higher FRZB expression. FRZB demonstrated chondrogenic and anti-hypertrophic properties in vitro. FRZB modulated cell adhesion pathway and cell spreading by regulating integrins expressions. Upstream miRNAs regulating FRZB expression were identified in DDH synovial fluid. Experiments indicated that downregulated miRNA-454 caused FRZB upregulation in DDH joint.

Conclusion: Dysregulated FRZB and its loci were associated with DDH. As a Wnt antagonist with chondrogenic properties, FRZB modulated cell adhesion pathway and cell spreading by regulating integrins expressions. FRZB in multiple DDH joint tissues might be mediated by the dysregulated miRNA expression profiles in the joint synovial fluid.

A novel arthroscopic classification of labral tear in hip dysplasia

Background

Acetabular labral tears cause of pain in patients with symptomatic hip dysplasia. To date, no structured grading system has been developed to evaluate labral tears in these patients. The present study describes a new system of grading labral tears in patients with acetabular dysplasia.

Methods

The data of 66 patients who underwent hip arthroscopy for symptomatic hip dysplasia from March 2014 to February 2018 were reviewed. Labral tears were classified into four groups, based on the occurrence of chondrolabral junction (CLJ) disruption, capsulolabral recess (CLR) disruption, and labral displacement. Labral tears without instability were classified as grade 1 or 2. Partial delamination or blistering of the labrum with minimal fraying at the CLJ was classified as grade 1, whereas labral tears with CLJ disruption were classified as grade 2. Unstable labral tears with CLR disruption followed by CLJ disruption, but without labral displacement, were classified as grade 3, whereas unstable labral tears with CLR and CLJ disruption, but with labral displacement, were classified as grade 4. The radiological and clinical characteristics of patients in each grade were determined including by simple radiographs and MRI/MR arthrography, as were concomitant findings, including rupture of the ligamentum teres, articular cartilage damage, and presence of a paralabral cyst. The surgical options selected for each grade and clinical outcomes, including modified Harris hip scores (mHHS) and Western Ontario and McMaster Universities Osteoarthritis index (WOMAC) scores, were evaluated. Spearman’s correlation analyses were performed to assess whether labral tear grade correlated with baseline characteristics, the incidence of concomitant injuries, and the severity of osteoarthritis (OA). The Wilcoxon test for paired data was performed to compare treatment results with pain scores.

Results

The study cohort included six men and 53 women of mean ± SD age 39.9 ± 13.0 years (range, 15–66 years). Of the 66 hips, seven (10.6%), 10 (15.2%), 30 (45.5%), and 19 (28.8%) were classified as grades 1–4, respectively. Symptom duration (P = 0.017), preoperative Tönnis OA grade (P < 0.001), cartilage damage (P < 0.001), and the presence of a paralabral cyst (P = 0.001) correlated significantly with baseline tear grade. In all groups, mHHS and WOMAC scores improved after surgical treatment.

Conclusions

Arthroscopic findings of labral tears in patients with hip dysplasia differed from the conventional classification. The classification system proposed in this study will likely be useful for determining the degree of labral tear in patients with hip dysplasia and for predicting treatment outcomes.

Advanced Magnetic Resonance Imaging in Osteoarthritis

Osteoarthritis (OA) is one of the most common causes of disability throughout the world. Current therapeutic strategies are aimed at preventing the development and delaying the progression of OA, as well as repairing or replacing worn articular surfaces, because the regeneration of lost hyaline articular cartilage is not currently a clinically feasible option. Imaging is useful in formulating treatment strategies in patients at risk for OA, allowing assessment of risk factors, the degree of preexisting tissue damage, and posttreatment monitoring. Magnetic resonance imaging (MRI), in particular, provides in-depth evaluation of these patients, with optimal clinical sequencing allowing sensitive assessment of chondral signal and morphology, and the addition of advanced MRI techniques facilitating comprehensive evaluation of joint health, with increased sensitivity for changes in articular cartilage and surrounding joint tissues.

Midterm-clinical Outcomes after Hip Arthroscopy in Middle-aged Patients with Early Osteoarthritis

Purpose

Although the number of hip arthroscopies is rapidly increasing in non-elderly patients, outcomes of this procedure in middle-aged patients are not well documented or clearly understood. The purpose of this study was to evaluate the clinical and radiological outcomes after hip arthroscopy in middle-aged patients with early osteoarthritis.

Materials and Methods

This retrospective study analyzed 189 patients with early osteoarthritis of various diagnoses aged 40 years or older who underwent hip arthroscopy between January 2010 and December 2015. Clinical (e.g., modified Harris hip score [mHHS], hip outcome score-activities of daily living [HOS-ADL], visual analogue scale [VAS] for pain, range of motion) and radiological (change of Tönnis grade) outcomes were assessed at a minimum of 3-year follow-up.

Results

The mean preoperative and final mHHS and HOS-ADL improved from 61.2 and 60.6 to 79.5 and 81.8, respectively, while the VAS pain score decreased from 6.3 to 3.2 (P<0.001). Although the mean range of internal rotation and flexion increased from 14.2 and 100.7° preoperatively to 30.4 and 110.6° at 1-year postoperatively, they decreased slightly to 27.4 and 105.4° at the final follow-up, respectively. Eight cases (4.2%) underwent revision arthroscopic surgery and three cases (1.6%) were converted to total hip arthroplasty.

Conclusion

Patients with early-stage osteoarthritis of various diagnoses achieved improved clinical outcomes. Therefore, using hip arthroscopy in middle-aged patients with early osteoarthritis, it is possible to achieve good surgical options.

Automatic MRI-based Three-dimensional Models of Hip Cartilage Provide Improved Morphologic and Biochemical Analysis

BACKGROUND

The time-consuming and user-dependent postprocessing of biochemical cartilage MRI has limited the use of delayed gadolinium-enhanced MRI of cartilage (dGEMRIC). An automated analysis of biochemical three-dimensional (3-D) images could deliver a more time-efficient and objective evaluation of cartilage composition, and provide comprehensive information about cartilage thickness, surface area, and volume compared with manual two-dimensional (2-D) analysis.

QUESTIONS/PURPOSES

(1) How does the 3-D analysis of cartilage thickness and dGEMRIC index using both a manual and a new automated method compare with the manual 2-D analysis (gold standard)? (2) How does the manual 3-D analysis of regional patterns of dGEMRIC index, cartilage thickness, surface area and volume compare with a new automatic method? (3) What is the interobserver reliability and intraobserver reproducibility of software-assisted manual 3-D and automated 3-D analysis of dGEMRIC indices, thickness, surface, and volume for two readers on two time points?

METHODS

In this IRB-approved, retrospective, diagnostic study, we identified the first 25 symptomatic hips (23 patients) who underwent a contrast-enhanced MRI at 3T including a 3-D dGEMRIC sequence for intraarticular pathology assessment due to structural hip deformities. Of the 23 patients, 10 (43%) were male, 16 (64%) hips had a cam deformity and 16 (64%) hips had either a pincer deformity or acetabular dysplasia. The development of an automated deep-learning-based approach for 3-D segmentation of hip cartilage models was based on two steps: First, one reader (FS) provided a manual 3-D segmentation of hip cartilage, which served as training data for the neural network and was used as input data for the manual 3-D analysis. Next, we developed the deep convolutional neural network to obtain an automated 3-D cartilage segmentation that we used as input data for the automated 3-D analysis. For actual analysis of the manually and automatically generated 3-D cartilage models, a dedicated software was developed. Manual 2-D analysis of dGEMRIC indices and cartilage thickness was performed at each "full-hour" position on radial images and served as the gold standard for comparison with the corresponding measurements of the manual and the automated 3-D analysis. We measured dGEMRIC index, cartilage thickness, surface area, and volume for each of the four joint quadrants and compared the manual and the automated 3-D analyses using mean differences. Agreement between the techniques was assessed using intraclass correlation coefficients (ICC). The overlap between 3-D cartilage volumes was assessed using dice coefficients and means of all distances between surface points of the models were calculated as average surface distance. The interobserver reliability and intraobserver reproducibility of the software-assisted manual 3-D and the automated 3-D analysis of dGEMRIC indices, thickness, surface and volume was assessed for two readers on two different time points using ICCs.

RESULTS

Comparable mean overall difference and almost-perfect agreement in dGEMRIC indices was found between the manual 3-D analysis (8 ± 44 ms, p = 0.005; ICC = 0.980), the automated 3-D analysis (7 ± 43 ms, p = 0.015; ICC = 0.982), and the manual 2-D analysis.Agreement for measuring overall cartilage thickness was almost perfect for both 3-D methods (ICC = 0.855 and 0.881) versus the manual 2-D analysis. A mean difference of -0.2 ± 0.5 mm (p < 0.001) was observed for overall cartilage thickness between the automated 3-D analysis and the manual 2-D analysis; no such difference was observed between the manual 3-D and the manual 2-D analysis.Regional patterns were comparable for both 3-D methods. The highest dGEMRIC indices were found posterosuperiorly (manual: 602 ± 158 ms; p = 0.013, automated: 602 ± 158 ms; p = 0.012). The thickest cartilage was found anteroinferiorly (manual: 5.3 ± 0.8 mm, p < 0.001; automated: 4.3 ± 0.6 mm; p < 0.001). The smallest surface area was found anteroinferiorly (manual: 134 ± 60 mm; p < 0.001, automated: 155 ± 60 mm; p < 0.001). The largest volume was found anterosuperiorly (manual: 2343 ± 492 mm; p < 0.001, automated: 2294 ± 467 mm; p < 0.001). Mean average surface distance was 0.26 ± 0.13 mm and mean Dice coefficient was 86% ± 3%. Intraobserver reproducibility and interobserver reliability was near perfect for overall analysis of dGEMRIC indices, thickness, surface area, and volume (ICC range, 0.962-1).

CONCLUSIONS

The presented deep learning approach for a fully automatic segmentation of hip cartilage enables an accurate, reliable and reproducible analysis of dGEMRIC indices, thickness, surface area, and volume. This time-efficient and objective analysis of biochemical cartilage composition and morphology yields the potential to improve patient selection in femoroacetabular impingement (FAI) surgery and to aid surgeons with planning of acetabuloplasty and periacetabular osteotomies in pincer FAI and hip dysplasia. In addition, this validation paves way to the large-scale use of this method for prospective trials which longitudinally monitor the effect of reconstructive hip surgery and the natural course of osteoarthritis.

LEVEL OF EVIDENCE

Level III, diagnostic study.

Location and Correlation of Acetabular Labral Tears and Paralabral Cysts Using Magnetic Resonance Imaging or Magnetic Resonance Arthrography in Patients With Femoroacetabular Impingement

PURPOSE

To evaluate the prevalence and location of paralabral cysts and the correlation between the type of femoroacetabular impingement (FAI) and acetabular labral tears, as well as the location of the paralabral cysts.

METHODS

Patients who received a diagnosis of FAI syndrome using plain radiography, magnetic resonance imaging or magnetic resonance arthrography, or computed tomographic arthrography from 2010 to 2015 were included in this study. The exclusion criteria were patients with arthritis (Tönnis grade 2 or greater) or dysplasia. We identified paralabral cysts and their location, size, configuration. Correlations between the type of FAI and labral tears and paralabral cysts were analyzed using the χ-square test.

RESULTS

Among 506 patients with FAI, paralabral cysts were found in 51 patients (55 hips) and were located anterosuperiorly in 40% of cases, posterosuperiorly in 36%, anteroinferiorly in 17%, and posteroinferiorly in 8%. We identified multilocular cysts in 60% of hips and unilocular cysts in 40%. Labral tears were radiographically found in 44 of 55 hips with paralabral cysts (80%); they were located anterosuperiorly in 59% and posterosuperiorly in 41%. Although paralabral cysts were found in the anteroinferior and posteroinferior areas, acetabular labral tears were not identified in the anteroinferior and posteroinferior areas. Classification of the type of FAI showed cam type in 14 of 55 hips (25.5%), pincer type in 16 (29%), mixed type in 7 (13%), labral tears in 15 (27%), and normal findings in 3 (5.5%). No correlation was found between the type of FAI and labral tears (P = .739) or the location of paralabral cysts (P = .228).

CONCLUSIONS

Paralabral cysts in patients with FAI most commonly are found in the anterosuperior area and are of the multilocular type. Although paralabral cysts in the anterosuperior and posterosuperior portions are related to labral tears, those in the anteroinferior and posteroinferior portions are not.

LEVEL OF EVIDENCE

Level IV, diagnostic case series.

Utility of radial reformation of three-dimensional fat-suppressed multi-echo gradient-recalled-echo images for the evaluation of acetabular labral injuries and femoroacetabular impingement

OBJECTIVES

To assess the utility of the radial reformation of three-dimensional fat-suppressed multi-echo gradient-recalled-echo (3D FS me-GRE) for evaluating acetabular labral injuries and femoroacetabular impingement (FAI).

MATERIALS AND METHODS

A total of 25 patients with suspected acetabular labral injuries were examined using 3D FS me-GRE and radial 2D T2*-weighted imaging (T2*WI) on a 3-T magnetic resonance imaging (MRI) scanner. The range of acetabular labral injuries was evaluated by radial reformation through the center of the acetabulum perpendicular to the plane across the entire acetabular rim (type 1 radial reformation) of 3D FS me-GRE and radial 2D T2*WI. To evaluate the FAI morphology, we performed radial reformation perpendicular to the central axis of the femoral head and neck (type 2 radial reformation) of 3D FS me-GRE.

RESULTS

Acetabular labral injuries were identified in 23 patients, and no acetabular labral injury was seen in two patients on type 1 radial reformation of 3D FS me-GRE and radial 2D T2*WI. The diagnostic concordance rate for the range of acetabular labral injuries between the two imaging methods was 76.0%, and there was excellent agreement for the injured angles (r = 0.977, p < 0.001). FAI morphology could be evaluated in all patients (no FAI, n = 8; cam, n = 10; pincer, n = 4; combined cam and pincer, n = 3) using type 2 radial reformation of 3D FS me-GRE.

CONCLUSIONS

Type 1 and type 2 radial reformations of 3D FS me-GRE imaging were useful for evaluating acetabular labral injuries and determining whether patients with acetabular labral injuries have FAI, respectively.

Analysis of acetabulum in children with developmental dysplasia of the hip by MRI scan

To review the value of acetabular magnetic resonance imaging (MRI) in children with developmental dysplasia of the hip (DDH) of different ages.Eighty-eight medical records of children with unilateral DDH who were diagnosed and treated in our hospital between January 2010 and December 2015 were retrospectively analyzed. The affected hips were put into the case group, and the normal hips were put into the control group. All cases were further divided into 3 age groups: infant (<1 year), 16 cases; young children (1-3 years), 48 cases; and children (3-13 years), 24 cases. The differences of the acetabular depth (AD), the bony acetabular index (BAI), and the cartilaginous acetabular index (CAI) between each group were measured and compared for a linear correlation analysis. At the same time, the distribution of the acetabular cartilage in the anterosuperior, top, and posterosuperior parts (the three parts) from the two groups was measured, respectively.Measurement results from both the case and control groups were as follows: AD was 5.46 ± 2.62 mm and 9.74 ± 2.33 mm; BAI was 33.26 ± 5.49° and 23.50 ± 5.33°; and CAI was 21.04 ± 6.16° and 12.71 ± 4.83°. Differences from the two groups were statistically significant (t = 11.94, 13.78, 9.16, P < .05); BAI and CAI were linearly correlated (r = 0.86, 0.75, P < .05). The AD in infant, young children, and children groups from the case group were 4.26 ± 0.42 mm, 4.79 ± 1.74 mm, and 7.31 ± 2.74 mm, respectively, which was statically significant as well (F = 11.37, P < .05). Under the same grouping criteria, BAI was recorded as 29.04 ± 5.11°, 34.56 ± 4.27°, and 33.12 ± 5.69°; CAI was recorded as 16.62 ± 5.50°, 21.79 ± 6.33°, and 20.91 ± 6.40° separately. There was a linear correlation (r = 0.78, 0.65, P < .05) between BAI and CAI in young children and children groups. The distribution of acetabular cartilage in the above-mentioned three parts from both young children and children groups was statistically significant (P < .05).MRI is a satisfactory imaging modality to children with DDH of different ages for the assessment of AD, BAI, CAI, and acetabular cartilage in multiple locations. It can provide ample imaging reference to clinical evaluation of the acetabulum development in DDH.

Correlations between intravoxel incoherent motion diffusion-weighted MR imaging parameters and 18F-FDG PET/CT metabolic parameters in patients with vertebral bone metastases: initial experience

OBJECTIVE

To investigate the relationship between intravoxel incoherent motion (IVIM) diffusion-weighted MRI (DW MRI) parameters and ¹⁸F-fluodeoxyglucose (FDG) (PET/CT) metabolic parameters in patients with vertebral bone metastases.

METHODS

19 patients with vertebral bone metastases were retrospectively included in this institutional review board-approved study. All patients underwent IVIM DW-MRI and ¹⁸F-FDG PET/CT before treatment. The IVIM parameters [molecular diffusion coefficient (D), perfusion fraction (f), and perfusion-related D (D*)] and apparent diffusion coefficient were acquired using 11 b-values (0, 10, 15, 20, 25, 50, 80, 120, 200, 300, and 800 s mm^-2). Maximum and mean standardized uptake values (SUVmax and SUVmean, respectively), metabolic tumor volume, and total lesion glycolysis derived from ¹⁸F-FDG PET/CT were calculated using thresholds of 3.0 SUV. The associations among parameters were evaluated by Spearman's correlation analysis.

RESULTS

A total of 19 patients and 41 regions of interest were included in this study. The IVIM parameter f was positively correlated with the metabolic parameters SUVmean and SUVmax [ρ = 0.499 (p < 0.01) and ρ = 0.413 (p < 0.01), respectively]. There was a weak positive correlation between D* and SUVmean (ρ = 0.321, p = 0.041).

CONCLUSION

IVIM perfusion-related parameters, especially f, were correlated with ¹⁸F-FDG PET/CT metabolic parameters in patients with vertebral bone metastases. IVIM DW-MRI, used to evaluate metabolic activity, appears to have diagnostic potential for bone metastasis and may also have utility in monitoring the post-treatment response. Advances in knowledge: The use of IVIM for vertebral bone metastasis is demonstrated. f may be more suitable to reflect the metabolic activity and may facilitate another diagnostic potential for monitoring the posttreatment response.

Cam Deformities and Limited Hip Range of Motion Are Associated With Early Osteoarthritic Changes in Adolescent Athletes: A Prospective Matched Cohort Study

BACKGROUND

The natural history of femoroacetabular impingement (FAI) remains incompletely understood. In particular, there is limited documentation of joint damage in adolescent patients with limited range of motion (LROM) of the hip, which is commonly associated with FAI.

PURPOSE

To evaluate changes in magnetic resonance imaging (MRI), radiographs, and clinical examinations over 5 years in a group of athletes from a wide variety of sports with asymptomatic LROM of the hip compared with matched controls.

STUDY DESIGN

Cohort study (prognosis); Level of evidence, 2.

METHODS

The authors screened 226 male and female athletes aged 12 to 18 years presenting for preparticipation sports physical examinations. Using a goniometer, we identified 13 participants with at least one hip having internal rotation <10° with the hip flexed to 90°. Overall, 21 of 26 hips (81%) had internal rotation <10°. These participants were age- and sex-matched to 13 controls with internal rotation >10°. At the time of enrollment, all participants were asymptomatic and underwent a complete hip examination and radiographic imaging with radiographs (anteroposterior [AP] and von Rosen views) and non-arthrogram MRI. Participants returned at 5-year follow-up and underwent repeat hip examinations, imaging (AP and lateral radiographs and non-arthrogram MRI), and hip function questionnaires. MRI scans were classified as "normal" versus "abnormal" based on the presence of any of 13 scored chondral, labral, or osseous abnormalities. Comparisons between the LROM group and control group were performed using generalized linear models (either linear, logistic, or log-binomial regression as appropriate for the outcome) with generalized estimating equations to account for the within-participant correlation due to patients having both hips included. Relative risk (RR) estimates are reported with 95% CIs.

RESULTS

At the time of study enrollment, 16 of 26 hips (62%) in the LROM group had abnormal MRI findings within the acetabular labrum or cartilage compared with 8 of 26 hips (31%) in the control group (RR, 2.0; 95% CI, 0.95-4.2; P = .067). The mean alpha angle measured from radial MRI sequences was 58° in the LROM group versus 44° in the control group ( P < .0001). In the LROM group, 13 of 26 hips (50%) had a positive anterior impingement sign, whereas 0 of 26 hips (0%) had a positive anterior impingement sign in the control group. At 5-year follow-up, 18 of 19 hips (95%) in the LROM group had abnormal MRI findings compared with 14 of 26 hips (54%) in the control group (RR, 1.7; 95% CI, 1.1-2.7; P = .014). New or progressive findings were documented on MRI in 15 of 20 hips in the LROM group compared with 8 of 26 hips in the control group (RR, 2.4; 95% CI, 1.2-4.8; P = .011). Six of 22 hips (27%) in the LROM group progressed from Tönnis grade 0 to Tönnis grade 1 in degenerative changes, whereas all 26 hips in the control group remained at Tönnis grade 0 on hip radiographs. In the LROM group, 11 of 22 hips (50%) had a positive anterior impingement sign, whereas 1 of 26 hips (4%) had a positive anterior impingement sign in the control group. A cam deformity (alpha angle >55° on lateral radiographs) was present in 20 of 22 hips (91%) in the LROM group and 12 of 26 hips (46%) in the control group ( P = .0165). The following variables at baseline were associated with an increased risk of degenerative changes at 5-year follow-up for the entire cohort: decreased hip internal rotation, positive anterior impingement sign, decreased hip flexion, increased alpha angle, and presence of a cam lesion.

CONCLUSION

At 5 years, young athletes with LROM of the hip showed increased progressive degenerative changes on MRI and radiographs compared with matched controls. Although the majority of these participants remained asymptomatic, those with features of FAI had radiographic findings consistent with early osteoarthritis. These outcomes suggest that more aggressive screening and counseling of young active patients may be helpful to prevent hip osteoarthritis in those with FAI.

Protocol for a multi-centre randomised controlled trial comparing arthroscopic hip surgery to physiotherapy-led care for femoroacetabular impingement (FAI): the Australian FASHIoN trial

BACKGROUND

Femoroacetabular impingement syndrome (FAI), a hip disorder affecting active young adults, is believed to be a leading cause of hip osteoarthritis (OA). Current management approaches for FAI include arthroscopic hip surgery and physiotherapy-led non-surgical care; however, there is a paucity of clinical trial evidence comparing these approaches. In particular, it is unknown whether these management approaches modify the future risk of developing hip OA. The primary objective of this randomised controlled trial is to determine if participants with FAI who undergo hip arthroscopy have greater improvements in hip cartilage health, as demonstrated by changes in delayed gadolinium-enhanced magnetic resonance imaging (MRI) of cartilage (dGEMRIC) index between baseline and 12 months, compared to those who undergo physiotherapy-led non-surgical management.

METHODS

This is a pragmatic, multi-centre, two-arm superiority randomised controlled trial comparing hip arthroscopy to physiotherapy-led management for FAI. A total of 140 participants with FAI will be recruited from the clinics of participating orthopaedic surgeons, and randomly allocated to receive either surgery or physiotherapy-led non-surgical care. The surgical intervention involves arthroscopic FAI surgery from one of eight orthopaedic surgeons specialising in this field, located in three different Australian cities. The physiotherapy-led non-surgical management is an individualised physiotherapy program, named Personalised Hip Therapy (PHT), developed by a panel to represent the best non-operative care for FAI. It entails at least six individual physiotherapy sessions over 12 weeks, and up to ten sessions over six months, provided by experienced musculoskeletal physiotherapists trained to deliver the PHT program. The primary outcome measure is the change in dGEMRIC score of a ROI containing both acetabular and femoral head cartilages at the chondrolabral transitional zone of the mid-sagittal plane between baseline and 12 months. Secondary outcomes include patient-reported outcomes and several structural and biomechanical measures relevant to the pathogenesis of FAI and development of hip OA. Interventions will be compared by intention-to-treat analysis.

DISCUSSION

The findings will help determine whether hip arthroscopy or an individualised physiotherapy program is superior for the management of FAI, including for the prevention of hip OA.

TRIAL REGISTRATION

Australia New Zealand Clinical Trials Registry reference: ACTRN12615001177549 . Trial registered 2/11/2015 (retrospectively registered).

SCFE: clinical aspects, diagnosis, and classification

PURPOSE

This article seeks to improve treatment outcomes in slipped capital femoral epiphysis (SCFE) by outlining advances in diagnosis, understanding of pathomechanics, and mechanically-based classification.

METHODS

Review of clinical experience with SCFE at our high-volume centre, interaction with other clinical experts, and literature review has allowed a current perspective to be articulated.

RESULTS

SCFE remains an important clinical problem, with late diagnosis still frequent. Improved understanding of the ubiquity of femoroacetabular impingement has guided current classification and treatment protocols.

CONCLUSION

SCFE is an important clinical problem, with high historical rates of impaired hip function both in childhood and adulthood. Great opportunities exist for improved outcomes following earliest possible clinical diagnosis, modern imaging, and mechanically-based classification of involved hips to allow optimal treatment.

How Does the dGEMRIC Index Change After Surgical Treatment for FAI? A Prospective Controlled Study: Preliminary Results

BACKGROUND

Delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) allows an objective, noninvasive, and longitudinal quantification of biochemical cartilage properties. Although dGEMRIC has been used to monitor the course of cartilage degeneration after periacetabular osteotomy (PAO) for correction of hip dysplasia, such longitudinal data are currently lacking for femoroacetabular impingement (FAI).

QUESTIONS/PURPOSES

(1) How does the mean acetabular and femoral dGEMRIC index change after surgery for FAI at 1-year followup compared with a similar group of patients with FAI treated without surgery? (2) Does the regional distribution of the acetabular and femoral dGEMRIC index change for the two groups over time? (3) Is there a correlation between the baseline dGEMRIC index and the change of patient-reported outcome measures (PROMs) at 1-year followup? (4) Among those treated surgically, can dGEMRIC indices distinguish between intact and degenerated cartilage?

METHODS

We performed a prospective, comparative, nonrandomized, longitudinal study. At the time of enrollment, the patients' decision whether to undergo surgery or choose nonoperative treatment was not made yet. Thirty-nine patients (40 hips) who underwent either joint-preserving surgery for FAI (20 hips) or nonoperative treatment (20 hips) were included. The two groups did not differ regarding Tönnis osteoarthritis score, preoperative PROMs, or baseline dGEMRIC indices. There were more women (60% versus 30%, p = 0.003) in the nonoperative group and patients were older (36 ± 8 years versus 30 ± 8 years, p = 0.026) and had lower alpha angles (65° ± 10° versus 73° ± 12°, p = 0.022) compared with the operative group. We used a 3.0-T scanner and a three-dimensional dual flip-angle gradient-echo technique for the dGEMRIC technique for the baseline and the 1-year followup measurements. dGEMRIC indices of femoral and acetabular cartilage were measured separately on the initial and followup radial dGEMRIC reformats in direct comparison with morphologic radial images. Regions of interest were placed manually peripherally and centrally within the cartilage based on anatomic landmarks at the clockface positions. The WOMAC, the Hip disability and Osteoarthritis Outcome Score, and the modified Harris hip score were used as PROMs. Among those treated surgically, the intraoperative damage according to the Beck grading was recorded and compared with the baseline dGEMRIC indices.

RESULTS

Although both the operative and the nonoperative groups experienced decreased dGEMRIC indices, the declines were more pronounced in the operative group (-96 ± 112 ms versus -16 ± 101 ms on the acetabular side and -96 ± 123 ms versus -21 ± 83 ms on the femoral side in the operative and nonoperative groups, respectively; p < 0.001 for both). Patients undergoing hip arthroscopy and surgical hip dislocation experienced decreased dGEMRIC indices; the decline in femoral dGEMRIC indices was more pronounced in hips after surgical hip dislocation (-120 ± 137 ms versus -61 ± 89 ms, p = 0.002). In the operative group a decline in dGEMRIC indices was observed in 43 of 44 regions over time. In the nonoperative group a decline in dGEMRIC indices was observed in four of 44 regions over time. The strongest correlation among patients treated surgically was found between the change in WOMAC and baseline dGEMRIC indices for the entire joint (R = 0.788, p < 0.001). Among those treated nonoperatively, no correlation between baseline dGEMRIC indices and change in PROMs was found. In the posterosuperior quadrant, the dGEMRIC index was higher for patients with intact cartilage compared with hips with chondral lesions (592 ± 203 ms versus 444 ± 205 ms, p < 0.001).

CONCLUSIONS

We found a decline in acetabular, femoral, and regional dGEMRIC indices for the surgically treated group at 1-year followup despite an improvement in all PROMs. We observed a similar but less pronounced decrease in the dGEMRIC index in symptomatic patients without surgical treatment indicating continuous cartilage degeneration. Although treatment of FAI is intended to alter the forces acting across the hip by eliminating impingement, its effects on cartilage biology are not clear. dGEMRIC provides a noninvasive method of assessing these effects. Longer term studies will be needed to determine whether the matrix changes of the bradytrophic cartilage seen here are permanent or clinically important.

LEVEL OF EVIDENCE

Level II, therapeutic study.

What MRI Findings Predict Failure 10 Years After Surgery for Femoroacetabular Impingement?

BACKGROUND

Magnetic resonance arthrogram (MRA) with radial cuts is presently the best available preoperative imaging study to evaluate chondrolabral lesions in the setting of femoroacetabular impingement (FAI). Existing followup studies for surgical treatment of FAI have evaluated predictors of treatment failure based on preoperative clinical examination, intraoperative findings, and conventional radiography. However, to our knowledge, no study has examined whether any preoperative findings on MRA images might be associated with failure of surgical treatment of FAI in the long term.

QUESTIONS/PURPOSES

The purposes of this study were (1) to identify the preoperative MRA findings that are associated with conversion to THA, any progression of osteoarthritis, and/or a Harris hip score of < 80 points after acetabuloplasty and/or osteochondroplasty of the femoral head-neck junction through a surgical hip dislocation (SHD) for FAI at a minimum 10-year followup; and (2) identify the age of patients with symptomatic FAI when these secondary degenerative findings were detected on preoperative radial MRAs.

METHODS

We retrospectively studied 121 patients (146 hips) who underwent acetabuloplasty and/or osteochondroplasty of the femoral head-neck junction through SHD for symptomatic anterior FAI between July 2001 and March 2003. We excluded 35 patients (37 hips) with secondary FAI after previous surgery and 11 patients (12 hips) with Legg-Calvé-Perthes disease. All patients underwent preoperative MRA to further specify chondrolabral lesions except in 19 patients (32 hips) including 17 patients (20 hips) who presented with an MRI from an external institution taken with a different protocol, 10 patients with no preoperative MRA because the patients had already been operated on the contralateral side with a similar appearance, and two patients (two hips) refused MRA because of claustrophobia. This resulted in 56 patients (65 hips) with idiopathic FAI and a preoperative MRA. Of those, three patients (three hips) did not have minimal 10-year followup (one patient died; two hips with followup between 5 and 6 years). The remaining patients were evaluated clinically and radiographically at a mean followup of 11 years (range, 10-13 years). Thirteen pathologic radiographic findings on the preoperative MRA were evaluated for an association with the following endpoints using Cox regression analysis: conversion to THA, radiographic evidence of any progression of osteoarthritis, and/or a Harris hip score of < 80. The age of the patient when each degenerative pattern was found on the preoperative MRA was recorded.

RESULTS

The following MRI findings were associated with one or more of our predefined failure endpoints: cartilage damage exceeding 60° of the circumference had a hazard ratio (HR) of 4.6 (95% confidence interval [CI], 3.6-5.6; p = 0.003) compared with a damage of less than 60°, presence of an acetabular rim cyst had a HR of 4.1 (95% CI, 3.1-5.2; p = 0.008) compared with hips without these cysts, and presence of a sabertooth osteophyte had a HR of 3.2 (95% CI, 2.3-4.2; p = 0.013) compared with hips without a sabertooth osteophyte. The degenerative pattern associated with the youngest patient age when detected on preoperative MRA was the sabertooth osteophyte (lower quartile 27 years) followed by cartilage damage exceeding 60° of the circumference (28 years) and the presence of an acetabular rim bone cyst (31 years).

CONCLUSIONS

Preoperative MRAs with radial cuts reveal important findings that may be associated with future failure of surgical treatment for FAI. Most of these factors are not visible on conventional radiographs or standard hip MRIs. Preoperative MRA evaluation is therefore strongly recommended on a routine basis for patients undergoing these procedures. Findings associated with conversion to arthroplasty, radiographic evidence of any progression of osteoarthritis, and/or a Harris hip score of < 80 points should be incorporated into the decision-making process in patients being evaluated for joint-preserving hip surgery.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Outcomes of joint preservation surgery: comparison of patients with developmental dysplasia of the hip and femoroacetabular impingement

Femoroacetabular impingement (FAI) and developmental dysplasia of the hip (DDH) are fundamentally and structurally different hip abnormalities yet their clinical presentation can often be very similar. We asked whether adult patients surgically treated for DDH when compared with FAI patients achieve (i) better outcome as reflected by the WOMAC Osteoarthritis Index, (ii) higher physical activity as reflected by the UCLA physical activity scale. Five hundred fifty-six patients treated by periacetabular osteotomy for DDH and 540 patients treated for FAI (cam, pincer, or combined) in nine high-volume centers, between 2008 and 2011 were matched using propensity analysis, based on age and BMI. After exclusions, 144 pairs were evaluated on WOMAC, SF-12 Health Survey, modified Harris Hip Score (mHHS) and UCLA scale at pre and post-operations. At pre-operative evaluation, FAI patients showed lower scores on WOMAC (total, stiffness, function) and SF-12 physical. Statistically significant improvements in the outcome scores were observed from pre to post-operative time points in both treatment groups. Once FAI and DDH patients were compared, FAI patients showed lower scores on most of the outcome measures. However, these differences diminished in time, with only SF-12 mental and mHHS scores remaining significantly lower at 2-year follow-up. Because of more advanced disease at presentation, patients with FAI had an inferior clinical outcome compared with patients with DDH after surgical correction. Further prospective studies are required to better describe the long-term clinical benefits of hip joint preservation surgery.

Hip Osteoarthritis: Etiopathogenesis and Implications for Management

Highly prevalent among the elderly, hip osteoarthritis (OA) carries a heavy burden of disease. Guidelines for the management of hip OA are often extrapolated from knee OA research, despite clear differences in the etiopathogenesis and response to treatments of OA at these sites. We propose that hip OA requires specific attention separate from other OA phenotypes. Our understanding of the etiopathogenesis of hip OA has seen significant advance over the last 15 years, since Ganz and colleagues proposed femoroacetabular impingement (FAI) as an important etiological factor. This narrative review summarizes the current understanding of the etiopathogenesis of hip OA and identifies areas requiring further research. Therapeutic approaches for hip OA are considered in light of the condition’s etiopathogenesis. The evidence for currently adopted management strategies is considered, especially those approaches that may have disease-modifying potential. We propose that shifting the focus of hip OA research and public health intervention to primary prevention and early detection may greatly improve the current management paradigm.

Hip dysplasia in the young adult caused by residual childhood and adolescent-onset dysplasia

Hip dysplasia is a treatable developmental disorder that presents early in life but if neglected can lead to chronic disability due to pain, decreased function, and early osteoarthritis. The main causes of hip dysplasia in the young adult are residual childhood developmental dysplasia of the hip (DDH) and adolescent-onset acetabular dysplasia. These two distinct disease processes affect the growing hip during different times of development but result in a similar deformity and pathomechanism of hip degeneration. Routine screening for DDH and counseling regarding risks for acetabular dysplasia in families with a history of early hip osteoarthritis may allow early identification and intervention in these hips with anatomical risk factors for joint degeneration.

Prognostic factors for mid-term symptom relief after open surgical correction for femoroacetabular impingement

BACKGROUND

We sought to identify, which patient and radiographic factors at preoperative and 1-year follow up will predict patient symptom relief at mid-term.

MATERIALS AND METHODS

A total of 50 hips in 47 patients with symptomatic FAI were included in this retrospective study. We stratified the hips into "success" and "failure" groups based on the change from baseline to mid-term follow up WOMAC pain score (mean follow up of 5.8 years). An attempt was made to identify factors that are predictive of mid-term outcome among preoperative radiographic measures, dGEMRIC index, range of motion and WOMAC score as well as 1-year follow-up range of motion, radiographic measures, and WOMAC pain scores.

RESULTS

At 1-year follow up, the success rate was 72% (36/50) and at mid-term follow the success rate increased to 82% (41/50). There were no significant associations between mid-term pain scores and baseline factors (all p-values ≥0.10). One-year pain score and hip internal rotation was associated with poor mid-term pain scores but only the 1-year pain score was associated with the mid-term success/failure outcome.

CONCLUSIONS

We did not identify clear preoperative predictors of mid-term results but patients with poor pain scores and limited hip internal rotation at 1-year follow-up are less likely to do well at mid-term.

Outcomes for Hip Arthroscopy According to Sex and Age: A Comparative Matched-Group Analysis

BACKGROUND

Factors such as age and sex are postulated to play a role in outcomes following arthroscopy for femoroacetabular impingement; however, to our knowledge, no data currently delineate outcomes on the basis of these factors. The purpose of this study was to compare clinical outcomes of patients undergoing hip arthroscopy for femoroacetabular impingement according to sex and age.

METHODS

One hundred and fifty patients undergoing hip arthroscopy for femoroacetabular impingement by a single fellowship-trained surgeon were prospectively analyzed, with 25 patients in each of the following groups: female patients younger than 30 years of age, female patients 30 to 45 years of age, female patients older than 45 years of age, male patients younger than 30 years of age, male patients 30 to 45 years of age, and male patients older than 45 years of age. The primary outcomes included the Hip Outcome Score Activities of Daily Living Subscale (HOS-ADL), Hip Outcome Score Sport-Specific Subscale (HOS-Sport), the modified Harris hip score (mHHS), and clinical improvement at the time of follow-up.

RESULTS

At a minimum 2-year follow-up, all groups demonstrated significant improvements in the HOS-ADL, the HOS-Sport, and the mHHS (p < 0.0001). Female patients older than 45 years of age scored significantly worse on the HOS-ADL, HOS-Sport, and mHHS compared with female patients younger than 30 years of age (p < 0.0001 for all) and female patients 30 to 45 years of age (p < 0.017 for all). Male patients older than 45 years of age scored significantly worse on all outcomes compared with male patients younger than 30 years of age (p ≤ 0.011 for all) and male patients 30 to 45 years of age (p ≤ 0.021 for all). Incorporating both sexes, patients older than 45 years of age scored significantly worse on all outcomes compared with patients younger than 30 years of age (p < 0.0001 for all) and patients 30 to 45 years of age (p ≤ 0.001 for all). Female patients older than 45 years of age had significantly reduced radiographic preoperative joint space width compared with the two other female groups and the male groups who were 45 years of age or younger (p < 0.05 for all).

CONCLUSIONS

Although all patients had significant improvements in all outcomes following hip arthroscopy, patients older than 45 years of age performed worse than younger patients, with female patients older than 45 years of age demonstrating the lowest outcome scores. In the age group of 45 years or younger, female patients performed as well as male patients in terms of hip clinical outcome scores. Overall, care must be individualized to optimize outcomes following hip arthroscopy for femoroacetabular impingement.

LEVEL OF EVIDENCE

Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.

Assessing risk factors for early hip osteoarthritis in activity-related hip pain: a Delphi study

OBJECTIVE

Hip pain and injury as a result of activity can lead to the development of early hip osteoarthritis (OA) in susceptible individuals. Our understanding of the factors that increase susceptibility continues to evolve. The ability to clearly identify individuals (and cohorts) with activity-related hip pain who are at risk of early hip OA is currently lacking. The purpose of this study was to gain expert consensus on which key clinical measures might help predict the risk of early hip OA in individuals presenting with activity-related hip pain. The agreed measures would constitute a standardised approach to initial clinical assessment to help identify these individuals.

METHODS

This Dephi study used online surveys to gain concordance of expert opinion in a structured process of 'rounds'. In this study, we asked 'What outcome measures are useful in predicting hip OA in activity-related hip pain?' The Delphi panel consisted of experts from sport and exercise medicine, orthopaedics, rheumatology, physiotherapy and OA research.

RESULTS

The study identified key clinical measures in the history, examination and investigations (plain anteroposterior radiograph and femoroacetabular impingement views) that the panel agreed would be useful in predicting future risk of hip OA when assessing activity-related hip pain. The panel also agreed that certain investigations and tests (eg, MR angiography) did not currently have a role in routine assessment. There was a lack of consensus regarding the role of MRI, patient-reported outcome measures (PROMs) and certain biomechanical and functional assessments.

CONCLUSIONS

We provide a standardised approach to the clinical assessment of patients with activity-related hip pain. Assessment measures rejected by the Delphi panel were newer, more expensive investigations that currently lack evidence. Assessment measures that did not reach consensus include MRI and PROMs. Their role remains ambiguous and would benefit from further research.

Preoperative Delayed Gadolinium-Enhanced Magnetic Resonance Imaging of Cartilage (dGEMRIC) for Patients Undergoing Hip Arthroscopy: Indices Are Predictive of Magnitude of Improvement in Two-Year Patient-Reported Outcomes

BACKGROUND

Delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC) has been used in the detection of chondropathy. Our study aimed to determine whether dGEMRIC indices are predictive of two-year patient-reported outcomes and pain scores following hip arthroscopy.

METHODS

Between August 2008 and April 2012, sixty-five patients (seventy-four hips) underwent primary hip arthroscopy with preoperative dGEMRIC and a minimum of two years of follow-up. Exclusion criteria were previous hip surgery, slipped capital femoral epiphysis, inflammatory arthropathy, Legg-Calvé-Perthes disease, and arthritis of >1 Tönnis grade. Patients were classified in two groups on the basis of a dGEMRIC cutoff of 323 msec, which was one standard deviation (SD) below the study cohort mean dGEMRIC index of 426 msec. Patient-reported outcome tools used included the modified Harris hip score (mHHS), the Nonarthritic Hip Score (NAHS), the Hip Outcome Score Activities of Daily Living (HOS-ADL), and the Hip Outcome Score Sport-Specific Subscale (HOS-SSS) as well as a visual analog scale (VAS) for pain and a patient satisfaction score.

RESULTS

There were sixty-four hips that met the inclusion criteria; fifty-two (81.3%) had a minimum of two years of follow-up. Twelve of the sixty-four hips had a dGEMRIC index of <323 msec (Group 1), and fifty-two hips had a dGEMRIC index of ≥323 msec (Group 2). There was no significant difference between the groups with respect to age, sex, and body mass index. There was no significant difference between the groups in mean preoperative patient-reported outcome scores and the VAS for pain. At the two-year follow-up, Group 1 had significant improvement in the mHHS, whereas Group 2 demonstrated significant improvement in all patient-reported outcome scores and the VAS. The improvement in all patient-reported outcome scores was significantly larger for Group 2 compared with Group 1. There was no significant difference in patient satisfaction between groups and no significant correlation between dGEMRIC indices and the patient-reported outcome measures.

CONCLUSIONS

Patients with a dGEMRIC index of ≥323 msec (less than one SD below the cohort mean) demonstrated significantly greater improvement in patient-reported outcome scores and the VAS for pain after hip arthroscopy.

Advanced Imaging in Femoroacetabular Impingement: Current State and Future Prospects

Symptomatic femoroacetabular impingement (FAI) is now a known precursor of early osteoarthritis (OA) of the hip. In terms of clinical intervention, the decision between joint preservation and joint replacement hinges on the severity of articular cartilage degeneration. The exact threshold during the course of disease progression when the cartilage damage is irreparable remains elusive. The intention behind radiographic imaging is to accurately identify the morphology of osseous structural abnormalities and to accurately characterize the chondrolabral damage as much as possible. However, both plain radiographs and computed tomography (CT) are insensitive for articular cartilage anatomy and pathology. Advanced magnetic resonance imaging (MRI) techniques include magnetic resonance arthrography and biochemically sensitive techniques of delayed gadolinium-enhanced MRI of cartilage (dGEMRIC), T1rho (T1ρ), T2/T2* mapping, and several others. The diagnostic performance of these techniques to evaluate cartilage degeneration could improve the ability to predict an individual patient-specific outcome with non-surgical and surgical care. This review discusses the facts and current applications of biochemical MRI for hip joint cartilage assessment covering the roles of dGEMRIC, T2/T2*, and T1ρ mapping. The basics of each technique and their specific role in FAI assessment are outlined. Current limitations and potential pitfalls as well as future directions of biochemical imaging are also outlined.

Scoring hip osteoarthritis with MRI (SHOMRI): A whole joint osteoarthritis evaluation system

BACKGROUND

To develop a semi-quantitative MR-based hip osteoarthritis (OA) evaluation system (Scoring hip osteoarthritis with MRI, SHOMRI), and to test its reproducibility and face validity.

METHODS

The study involved 98 subjects with informed consent. Three-Tesla MR imaging of hip was performed in three planes with intermediate-weighted fat saturated FSE sequences. Two radiologists assessed cartilage loss, bone marrow edema pattern, subchondral cyst in 10 subregions, and assessed labrum in 4 subregions. In addition, presence or absence of ligamentum teres integrity, paralabral cysts, intra-articular body, and effusion in the hip joint were analyzed using the SHOMRI system. The reproducibility was assessed with intra-class correlation coefficient (ICC), Cohen's Kappa values and percent agreement. SHOMRI scores were correlated with radiographic Kellgren-Lawrence (KL) and OARSI atlas gradings, and clinical parameters, the hip osteoarthritis outcome score (HOOS) and hip range of motion (ROM), using Spearman's rank correlation and ordinal logistic regression.

RESULTS

ICC values were in the excellent range, 0.91 to 0.97. Cohen's Kappa values and percent agreement ranged from 0.55 to 0.79 and 66 to 99%, respectively. SHOMRI demonstrated significant correlations with KL and OARSI gradings as well as with clinical parameters, HOOS and ROM (P < 0.05). Among the SHOMRI features, subchondral cyst and bone marrow edema pattern showed the highest correlation with HOOS and ROM.

CONCLUSION

SHOMRI demonstrated moderate to excellent reproducibility and significant correlation with radiographic gradings and clinical parameters.

Imaging strategies for assessing cartilage composition in osteoarthritis

Efforts to reduce the ever-increasing rates of osteoarthritis (OA) in the developed world require the ability to non-invasively detect the degradation of joint tissues before advanced damage has occurred. This is particularly relevant for damage to articular cartilage because this soft tissue lacks the capacity to repair itself following major damage and is essential to proper joint function. While conventional magnetic resonance imaging (MRI) provides sufficient contrast to visualize articular cartilage morphology, more advanced imaging strategies are necessary for understanding the underlying biochemical composition of cartilage that begins to break down in the earliest stages of OA. This review discusses the biochemical basis and the advantages and disadvantages associated with each of these techniques. Recent implementations for these techniques are touched upon, and future considerations for improving the research and clinical power of these imaging technologies are also discussed.

Accuracy of 3D dual echo steady state (DESS) MR arthrography to quantify acetabular cartilage thickness

PURPOSE

To deploy and quantify the accuracy of 3D dual echo steady state (DESS) MR arthrography with hip traction to image acetabular cartilage. Clinical magnetic resonance imaging (MRI) sequences used to image hip cartilage often have reduced out-of-plane resolution and may lack adequate signal-to-noise to image cartilage.

MATERIALS AND METHODS

Saline was injected into four cadaver hips placed under traction. 3D DESS MRI scans were obtained before and after cores of cartilage were harvested from the acetabulum; the two MRIs were spatially aligned to reference core positions. The thickness of cartilage cores was measured under microscopy to serve as the reference standard. 3D reconstructions of cartilage and subchondral bone were generated using automatic and semiautomatic image segmentation. Cartilage thickness estimated from the 3D reconstructions was compared to physical measurements using Bland-Altman plots.

RESULTS

As revealed by the automatic segmentation mask, saline imbibed the joint space throughout the articulating surface, with the exception of the posteroinferior region in two hips. Locations where air bubbles were introduced and regions of suspected low density bone disrupted an otherwise smooth automatic segmentation mask. Automatic and semiautomatic segmentation yielded a bias ± repeatability coefficient (95% limits of agreement) of 0.10 ± 0.51 mm (-0.41 to 0.61 mm) and 0.06 ± 0.43 mm (-0.37 to 0.49 mm), respectively.

CONCLUSION

Cartilage thickness can be estimated to within ∼0.5 mm of the physical value with 95% confidence using 3D reconstructions of 3D DESS MR arthrography images. Manual correction of the automatic segmentation mask may improve reconstruction accuracy.

Femoroacetabular impingement negates the acetabular labral seal during pivoting maneuvers but not gait

BACKGROUND

Experimental disruption of the labrum has been shown to compromise its sealing function and alter cartilage lubrication. However, it is not known whether pathological changes to the labrum secondary to femoroacetabular impingement (FAI) have a similar impact on labral function.

QUESTIONS/PURPOSES

Does damage to the labrum occurring in association with abnormal femoral morphology affect the labral seal?

METHODS

Using 10 fresh cadaveric specimens (mean age 50 years, ±8), we measured the capacity of the central compartment of the hip (the iliofemoral joint) to maintain a seal during fluid infusion, which may help elucidate the function of the labrum during weightbearing. Specimens with and without abnormal femoral morphology (six normal-appearing specimens and four whose geometry suggested cam-type FAI) were tested in postures observed during functional activities, including simulations of normal gait, stooping, and pivoting. Each specimen with FAI morphology exhibited secondary damage of the labrum and the adjacent chondral surface, whereas specimens of normal morphology were undamaged.

RESULTS

Average peak central compartment pressure was reduced during pivoting for specimens with the presence of labral damage secondary to FAI. When placed in pivoting positions, hips with FAI maintained lower fluid pressures within the central compartment compared with intact specimens (15±3 versus 42±8 kPa, respectively; effect size: 1.08 [-0.36 to 2.31]; p=0.007). No differences in peak pressure were observed between groups (FAI versus normal) for postures simulating either gait (21±6 versus 22±4 kPa; p=0.902) or stooping (9±2 versus 8±3 kPa; p=0.775) with the numbers available.

CONCLUSIONS

The acetabular seal, quantified by the maximum intraarticular pressure, was reduced during pivoting; however, the seal was maintained during simulated gait and stooping.

CLINICAL RELEVANCE

Because degeneration is progressive with repetitive impingement, loss of the labral seal starts to be seen during pivoting and may progress from there, but in this small-sample cadaver study that evaluated specimens in middle adulthood, the seal remains intact during simulated gait and stooping. Our study suggests that labral damage secondary to cam-type FAI may reduce the ability of the labral to provide an adequate seal of the central compartment of the hip during loading; however, the extent to which this is affected requires further investigation.

Severity mapping of the proximal femur: a new method for assessing hip osteoarthritis with computed tomography

OBJECTIVE

Plain radiography has been the mainstay of imaging assessment in osteoarthritis for over 50 years, but it does have limitations. Here we present the methodology and results of a new technique for identifying, grading, and mapping the severity and spatial distribution of osteoarthritic disease features at the hip in 3D with clinical computed tomography (CT).

DESIGN

CT imaging of 456 hips from 230 adult female volunteers (mean age 66 ± 17 years) was reviewed using 3D multiplanar reformatting to identify bone-related radiological features of osteoarthritis, namely osteophytes, subchondral cysts and joint space narrowing. Scoresheets dividing up the femoral head, head-neck region and the joint space were used to register the location and severity of each feature (scored from 0 to 3). Novel 3D cumulative feature severity maps were then created to display where the most severe disease features from each individual were anatomically located across the cohort.

RESULTS

Feature severity maps showed a propensity for osteophytes at the inferoposterior and superolateral femoral head-neck junction. Subchondral cysts were a less common and less localised phenomenon. Joint space narrowing <1.5 mm was recorded in at least one sector of 83% of hips, but most frequently in the posterolateral joint space.

CONCLUSIONS

This is the first description of hip osteoarthritis using unenhanced clinical CT in which we describe the co-localisation of posterior osteophytes and joint space narrowing for the first time. We believe this technique can perform several important roles in future osteoarthritis research, including phenotyping and sensitive disease assessment in 3D.

Increasing substance P levels in serum and synovial tissues from patients with developmental dysplasia of the hip (DDH)

BACKGROUND

The tachykininergic neurotransmitters have been proved to be involved in the inflammatory progress and chronic pain in series of disease. The present study was undertaken to evaluate the levels of substance P (SP) and its receptors NK-1 receptor (NK-1R) in both serum and synovial tissues of hip joint from patients with different stages of DDH, and to detect the possible correlation of serum SP levels with pain sensation and dysfunction of the hip joint.

METHODS

SP levels in serum and synovial tissues from patients with DDH and DDH combined with osteoarthritis (DDH&OA) group were compared through immunohistochemistry (IHC), ELISA, and 2-step acetic acid extraction method respectively. Expression of NK-1R in synovial tissues was compared through IHC, quantitive Real-Time PCR (QRT-PCR) and Western-Blot. The severities of pain sensation and the functional activities of hip joint were assessed by Visual analogue scale (VAS) and Harris hip score (HHS). Correlations of serum SP levels with VAS, HHS and erythrocyte sedimentation rate (ESR) were evaluated respectively in these groups.

RESULTS

Significantly elevated serum SP levels were detected in group of DDH and DDH&OA compared to that in normal group. IHC, QRT-PCR as well as tissue Elisa showed that SP levels in synovial tissue of DDH&OA group is stronger than that in DDH group. Serum SP levels in each group have no gender differences. The enhanced SP levels in synovial tissue mainly came from the segregation of peripheral nerve endings. Serum SP correlated with VAS and HHS in patients with DDH&OA (Male + Female). Serum SP correlated with HHS in patients with DDH (Male). Serum SP levels also correlated with erythrocyte sedimentation rate (ESR) in patients with DDH&OA (Male + Female). Up-regulated expression of NK-1R was also observed in synovial tissue of patients with DDH&OA compared to patients with DDH, through western-blot, IHC, and QRT-PCR.

CONCLUSIONS

These findings indicated that the increasing SP levels in serum and synovial tissues, observed from patients with DDH to patients with DDH&OA, might associate with the loss of function and chronic pain sensation in hip joint. SP along with its receptors NK-1R might be involved in the progression of DDH into DDH&OA. In the future, inhibitors of SP as well as NK-1R may represent a novel pharmacotherapy target for pain relieving, inflammation alleviating and joint degeneration delaying for patients with DDH.

Anteroinferior acetabular rim damage due to femoroacetabular impingement

BACKGROUND

The most common location of labral tears and chondral damage in the hip is the anterosuperior region of the acetabulum, which is associated with pain in flexion and rotation. We describe a case series of patients with labral tears, ganglion formation, and chondromalacia isolated to the anteroinferior acetabulum. Clinically, patients had pain in extension and internal rotation.

CASE DESCRIPTIONS

Isolated anteroinferior labral hypertrophy and ganglion were first observed in a patient with coxa valga. We retrospectively reviewed clinical and radiographic records and identified nine hips in seven patients with isolated anteroinferior damage. One patient with bilateral valgus femoral head tilt after slipped capital femoral epiphysis (SCFE) had impingement of the anteromedial metaphysis on the acetabulum from 3 to 6 o'clock. Five of seven had valgus neck-shaft angles and all had acetabular anteversion with damage isolated to the anteroinferior acetabular rim.

LITERATURE REVIEW

Series on the diagnostic efficacy of MR arthrogram have noted anteroinferior damage adjacent to superior acetabular rim lesions. However, these do not describe isolated anteroinferior rim damage. In addition, available case series of patients with valgus SCFE do not describe a location of impingement or intraarticular damage.

PURPOSES AND CLINICAL RELEVANCE

In this small case series of patients with isolated anteroinferior chondrolabral damage, there are two potential causative mechanisms: (1) primary anteroinferior impingement with femoral extension and internal rotation and (2) posterior extraarticular ischiotrochanteric impingement causing secondary anterior instability of the femur. The pathoanatomy appears to be multifactorial, necessitating an individualized treatment approach.

Methodologies for semiquantitative evaluation of hip osteoarthritis by magnetic resonance imaging: approaches based on the whole organ and focused on active lesions

OBJECTIVE

As a wider variety of therapeutic options for osteoarthritis (OA) becomes available, there is an increasing need to objectively evaluate disease severity on magnetic resonance imaging (MRI). This is more technically challenging at the hip than at the knee, and as a result, few systematic scoring systems exist. The OMERACT (Outcome Measures in Rheumatology) filter of truth, discrimination, and feasibility can be used to validate image-based scoring systems. Our objective was (1) to review the imaging features relevant to the assessment of severity and progression of hip OA; and (2) to review currently used methods to grade these features in existing hip OA scoring systems.

METHODS

A systematic literature review was conducted. MEDLINE keyword search was performed for features of arthropathy (such as hip + bone marrow edema or lesion, synovitis, cyst, effusion, cartilage, etc.) and scoring system (hip + OA + MRI + score or grade), with a secondary manual search for additional references in the retrieved publications.

RESULTS

Findings relevant to the severity of hip OA include imaging markers associated with inflammation (bone marrow lesion, synovitis, effusion), structural damage (cartilage loss, osteophytes, subchondral cysts, labral tears), and predisposing geometric factors (hip dysplasia, femoral-acetabular impingement). Two approaches to the semiquantitative assessment of hip OA are represented by Hip OA MRI Scoring System (HOAMS), a comprehensive whole organ assessment of nearly all findings, and the Hip Inflammation MRI Scoring System (HIMRISS), which selectively scores only active lesions (bone marrow lesion, synovitis/effusion). Validation is presently confined to limited assessment of reliability.

CONCLUSION

Two methods for semiquantitative assessment of hip OA on MRI have been described and validation according to the OMERACT Filter is limited to evaluation of reliability.

Differences in the locations and modes of labral tearing between dysplastic hips and those with femoroacetabular impingement

We investigated differences in the location and mode of labral tears between dysplastic hips and hips with femoroacetabular impingement (FAI). We also investigated the relationship between labral tear and adjacent cartilage damage. We retrospectively studied 72 symptomatic hips (in 68 patients: 19 men and 49 women) with radiological evidence of dysplasia or FAI on high-resolution CT arthrography. The incidence and location of labral tears and modes of tear associated with the base of the labrum (Mode 1) or body of the labrum (Mode 2) were compared among FAI, mildly dysplastic and severely dysplastic hips. The locations predominantly involved with labral tears were different in FAI and mild dysplastic hips (anterior and anterosuperior zones) and in severely dysplastic hips (anterosuperior and superior zones) around the acetabulum. Significant differences were observed in the prevalence of Mode 1 versus Mode 2 tears in FAI hips (72% (n = 13) vs 28% (n = 5)) and severe dysplastic hips (25% (n = 2) vs 75% (n = 6)). The frequency of cartilage damage adjacent to Mode 1 tears was significantly higher (42% (n = 14)) than that adjacent to Mode 2 tears (14% (n = 3)).

Hip pathology is significantly related to the locations and modes of labral tears. Mode 1 tears may be a risk factor for the development of adjacent acetabular cartilage damage.

Cite this article: Bone Joint J 2013;95-B:1320–5.