Is There an Association Between Borderline-to-mild Dysplasia and Hip Osteoarthritis? Analysis of CT Osteoabsorptiometry

Paradoxical Change in Subchondral Bone Density in the Medial Compartment of the Proximal Tibial Articular Surface After High Tibial Osteotomy: A Detailed Subchondral Bone Density Analysis

BACKGROUND

High tibial osteotomy (HTO) aims to realign the varus knee to alleviate stress in the medial compartment. However, detailed information on the impact of HTO on stress distribution across the tibiofemoral joint surface still needs to be completely elucidated.

PURPOSE/HYPOTHESIS

The present study aimed to analyze the subchondral bone density distribution to validate the alignment threshold causing paradoxical changes. We hypothesized that there would be a paradoxical stress change in the medial compartment beyond a specific threshold for lower limb realignment after HTO.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

A retrospective clinical study of 32 knees from 30 patients who underwent medial opening-wedge HTO between 2015 and 2019 was conducted at Hokkaido University Hospital. The subchondral bone density across the tibiofemoral joint was analyzed using computed tomography-osteoabsorptiometry before and after HTO. The high-density area (HDA) within the medial and lateral compartments and their subregions, which were quartered in the coronal plane, was specifically examined.

RESULTS

The hip-knee-ankle angle, medial proximal tibial angle (MPTA), joint line obliquity (JLO), and joint line convergence angle significantly changed after HTO (P < .01). The HDA of the medial compartment to the total HDA ratio decreased from 83% to 77%. Paradoxically, the HDA in the most central subregion of the medial compartment increased from 24% to 30%. There were significant differences between MPTA and JLO in patients with and without paradoxical changes in the HDA. MPTA and JLO cutoff values causing paradoxical changes in the HDA were 94° and 4°, respectively.

CONCLUSION

There was a paradoxical stress increase in the M4 region at the medial compartment associated with the MPTA and JLO beyond specific thresholds. Therefore, surgical planning should be cautiously performed to prevent overcorrection, which can lead to adverse stress distribution changes.

No Difference in Patient-Reported Outcomes for Periacetabular Osteotomy and Hip Arthroscopy With Capsular Plication in the Setting of Borderline Hip Dysplasia: A Propensity-Matched Multicenter Study With Minimum 5-Year Follow-Up

PURPOSE

To compare minimum 5-year patient-reported outcome measures after hip arthroscopy (HA) and periacetabular osteotomy (PAO) for borderline hip dysplasia.

METHODS

Hips with a lateral center-edge angle (LCEA) between 18° and less than 25° that underwent either PAO or HA were selected from 2 institutions. The exclusion criteria were as follows: LCEA less than 18°, Tönnis osteoarthritis grade greater than 1, prior hip surgical procedures, active inflammatory disease, Workers' Compensation, and concomitant surgery. Patients underwent propensity matching based on age, sex, body mass index, and Tönnis osteoarthritis grade. Patient-reported outcome measures included the modified Harris Hip Score, as well as calculation of the minimal clinically important difference, patient acceptable symptom state, and maximum outcome improvement satisfaction threshold. Preoperative radiographic predictors included comparison of the Femoro-epiphyseal Acetabular Roof index and ligamentum teres lesions.

RESULTS

A total of 28 PAO patients underwent propensity matching to 49 HA patients. The 2 groups were similar in terms of mean age, sex, preoperative body mass index, and LCEA. The PAO group had a longer mean follow-up period (95.8 months vs 81.3 months, P = .001). The mean Femoro-epiphyseal Acetabular Roof index was significantly lower preoperatively in the HA group (P < .001). The 2 groups showed similar and significant improvements in the mean modified Harris Hip Score from preoperatively to latest follow-up (P < .001). The relative risk of subsequent surgery in the PAO group was 3.49 (P = .024), mostly attributed to hardware removal (25%). The revision rate was 3.6% in the PAO group and 8.2% in the HA group (P = .65). One patient in the PAO group required revision HA for intra-articular adhesions. Three of the patients requiring revision in the HA group underwent PAO because of persistent pain, and one underwent revision HA alone. Conversion to total hip arthroplasty was required in 1 patient in the HA group and no patients in the PAO group.

CONCLUSIONS

Both PAO and HA with capsular plication provide borderline hip dysplasia patients with clinically significant improvements and low revision rates at a minimum of 5 years postoperatively.

LEVEL OF EVIDENCE

Level III, retrospective, comparative therapeutic trial.

Are there associations between hip geometry and bone quality? An analysis on 3074 adults from a general population

INTRODUCTION

Patients with reduced bone mineral density and altered hip geometry are susceptible for hip pathologies. Knowledge on associations between bone properties and hip geometric parameters might facilitate identification of patients at risk for hip pathologies. The aim of the present study was to identify associations of bone properties assessed by quantitative ultrasound (QUS) at the heel and hip geometric parameters like center-edge angle (CE), neck-shaft angle (NSA) and alpha angle.

MATERIALS AND METHODS

Hip geometric parameters (CE, NSA and alpha angle) of 3074 participants from the population-based Study of Health in Pomerania were assessed on magnetic resonance imaging. QUS was performed on both calcanei providing broadband ultrasound attenuation (BUA), speed of sound (SOS) and stiffness-index. Based on the stiffness-index the individual osteoporotic fracture risk (low, moderate or high) was determined. Associations between QUS-based and hip geometric parameters were calculated in linear regression models adjusted for age, sex, body height and weight. Interactions of QUS markers with age and sex on hip geometric parameters were tested.

RESULTS

Significant inverse associations between BUA (β = - 0.068), SOS (β = - 0.024) as well as stiffness-index (β = - 0.056) and CE were present, while fracture risk was positively associated with CE (β for high = 1.28 and moderate = 2.54 vs. low fracture risk). Interactions between BUA and sex as well as between SOS and age were detected in the models for CE. Furthermore, there was an inverse relation between fracture risk and NSA that was restricted to the moderate risk (β for moderate vs. low fracture risk = - 0.60). There were no significant associations between QUS parameters and alpha angle.

CONCLUSIONS

In the general population, several associations between QUS-based bone properties or fracture risk and hip geometry are present. Less dysplastic hips had a lower stiffness-index and a higher fracture risk, whereas more valgus hips had a lower fracture risk.

Femoral head translation in borderline and definite dysplastic hips during weight-bearing: 2D/3D image registration analysis

PURPOSE

The aims of this study were to 1) assess femoral head translation during weight-bearing in symptomatic developmental dysplasia of the hip (DDH) and 2) compare it between borderline DDH and definite DDH.

METHODS

The study included four individuals with borderline DDH and nine with definite DDH, scheduled for periacetabular osteotomy. Anteroposterior X-ray images of the hip joint were obtained in the standing position, and computed tomography images of the pelvis were obtained in the supine position. Femoral head translation from the supine to a standing position was measured using 2D/3D X-ray image registration.

RESULTS

From a supine to a standing position, the femoral head translated 0.3 mm laterally, 0.5 mm anteriorly, and 0.5 mm superiorly on average. The mean femoral head translation in 3D between the supine and standing positions was 1.5 mm. The 3D femoral head translation in the borderline DDH group was significantly greater than that in the definite DDH group. In the definite DDH group, there was a significant correlation between the center edge (CE) angle and 3D femoral head translation (ρ = -0.78, P = 0.012).

CONCLUSIONS

Symptomatic DDH showed femoral head translation in the anterior, lateral, and superior directions during weight-bearing. In definite DDH, the amount of femoral head translation was negatively correlated with the CE angle. The amount of 3D translation in patients with borderline DDH was larger than that in definite DDH. Dynamic joint instability during weight-bearing was observed in borderline DDH as well as definite DDH. Treatment to enhance joint stability during weight-bearing is important in both cases.

The sourcil roundness index is a useful measure for quantifying acetabular concavity asphericity

This study aimed to clarify the clinical utility of the sourcil roundness index (SRI), a novel index for quantifying the asphericity of the acetabular concavity, by determining (1) the difference in the SRI between dysplastic and normal hips and (2) the correlation between the SRI and radiographic parameters of hip dysplasia. We reviewed standing anteroposterior pelvic radiographs of 109 dysplastic and 40 normal hips. The SRI was determined as the ratio of the distance from the medial edge of the sourcil to the most concave point of the acetabular sourcil (A) to the distance from the medial to the lateral edge of the sourcil (B). The formula for SRI is (A/B) × 100-50 (%), with an SRI of 0% indicating a perfectly spherical acetabulum, and higher SRI values indicating a more aspherical shape. The median SRI was greater in patients with hip dysplasia than in normal hips (5.9% vs. - 1.4%; p < 0.001). Furthermore, the median SRI was greater in the severe dysplasia subgroup (18.9%) than in the moderate (3.5%) and borderline-to-mild (- 1.3%) dysplasia subgroups (p < 0.05). Quantification of acetabular concavity asphericity by the SRI showed that dysplastic hips had a more lateral acetabular concave point than normal hips, and that the severity of hip dysplasia had an effect on the acetabular concavity asphericity.

Effect of periacetabular osteotomy on the distribution pattern of subchondral bone mineral density in patients with hip dysplasia

Despite the availability of long-term follow-up data, the effect of pelvic osteotomy on the natural history of osteoarthritis is not yet fully understood, partly because there is untapped potential for radiographs to better describe osteoarthritis. Therefore, this study aimed to assess the distribution of subchondral bone mineral density (BMD) across the acetabulum in patients with hip dysplasia immediately (2 weeks) and 1 year after undergoing periacetabular osteotomy (PAO). To that end, we reviewed 40 hips from 33 patients with developmental dysplasia of the hip who underwent PAO between January 2016 and July 2019 at our institution. We measured subchondral BMD through the articular surface of the acetabulum using computed tomography osteoabsorptiometry, dividing the distribution map into nine segments. We then compared the subchondral BMD between 2 weeks and 1 year after PAO in each area. At 2 weeks after PAO, the high-density area tended to be localized particularly in the lateral part of the acetabulum, whereas 1 year after PAO, the high-density area moved to the central and lateral parts. The percentage ratios of the subchondral BMD for the central-posterior, lateral-central, and lateral-posterior areas relative to the central-central area were significantly decreased at 1 year after PAO, as compared to those at 2 weeks after PAO. These findings suggest that loading was altered by PAO to be more similar to physiological loading. A long follow-up observational study is warranted to confirm the association between early changes in subchondral BMD by PAO and joint degeneration.

Influence of differences in bone morphology on the distribution patterns of subchondral bone density across the trapeziometacarpal joint

We aimed to clarify the effects of morphological patterns of the trapezium and first metacarpal on the distribution of subchondral bone density across the articular surface of the trapeziometacarpal (TMC) joint using computed tomography osteoabsorptiometry. Thirty-three patients with normal TMC joints were evaluated. The percentages of the high-density areas in the radial-dorsal and ulnar-volar regions of the trapezium were significantly higher than that in the ulnar-dorsal region, and that of the ulnar-dorsal region of the first metacarpal was significantly lower than in the other three regions. The percentage of the high-density area of the radial-dorsal region of the trapezium and trapezial inclination (TI) showed a significant positive correlation, and the percentages of the high-density areas in the ulnar-dorsal and ulnar-volar regions had significant negative correlations with TI at the articular surface of the first metacarpal. These results indicate that bony morphologic differences in the trapezium affect the distribution pattern of subchondral bone density through the TMC joint.

Stress on the posteromedial region of the proximal tibia increased over time after anterior cruciate ligament injury

PURPOSE

Anterior cruciate ligament (ACL) injury induces anterior and rotatory instability of the knee. However, the effect of this instability on the stress distribution in the knee joint in living participants is not clear. The aim of this study was to compare the distribution pattern of subchondral bone density across the proximal tibia in the knees with and without ACL injury, and to investigate the correlation between the distribution patterns of the subchondral bone density and the duration of ACL-deficiency.

METHODS

Radiographic and computed tomography (CT) data pertaining to 20 patients with unilateral ACL injury without combined injury (ACL-deficient group) and 19 nontraumatic subjects (control group) were collected retrospectively. Subchondral bone density of the proximal tibia was assessed using CT-osteoabsorptiometry. Both the medial and lateral compartments of the proximal tibia were divided into three subregions of equal width in the sagittal direction. The percentage of high subchondral bone density areas (HDA%) in each subregion was quantitatively analyzed.

RESULTS

HDA% of the posteromedial region was significantly higher in the ACL-deficient group (mean: 21.6%) than in the control group (14.7%) (p = 0.002). In contrast, HDA% of the anteromedial region was significantly lower in the ACL-deficient group (9.4%) than in the control group (15.3%) (p = 0.048). The logarithm of the time elapsed from ACL injury to CT examination showed a significant correlation with HDA% in the posteromedial region (p = 0.032).

CONCLUSIONS

Subchondral bone density in the posteromedial region significantly increased after ACL injury and correlated with the duration of ACL-deficiency in semi-log manner in meniscus intact knees. The increase in stress on the posteromedial region after ACL injury, which induces a change in the subchondral bone density, justifies early ACL reconstruction after ACL injury.

Central acetabular osteophytes (CAO) are more prevalent in the borderline developmental dysplastic hip (BDDH) patients: a propensity-score matched CT study

Background

The acetabular fossa often showing the first signs of degeneration, Central acetabular osteophytes (CAO) have been increasingly recognized during hip arthroscopy. The purpose of this study was to investigate the condition of CAO in BDDH hips and compare cotyloid fossa size between the BDDH and the non-BDDH hips on CT images.

Methods

We performed a retrospective analysis of prospectively collected data of hip CT images of FAI or labral injury patients. A 1:2 propensity-score matched observational study comparing the linear length of cotyloid fossa was analyzed. Cotyloid fossa width (CFW) and cotyloid notch width (CNW) were measured on axial images, cotyloid fossa height (CFH) and cotyloid fossa depth (CFD) were measured on coronal images. Within the CAO patients, we performed central acetabular decompression (CAD) and then observed the morphology change in fossa.

Results

Propensity-score matching yielded 61 BDDH hips and 122 non-BDDH hips. BDDH hips had a higher prevalence of CAO and a decreased linear length of cotyloid fossa (CFW, CFH and CNW). In the BDDH group, 33 hips underwent CAD, postoperative CFW, CFH and CNW were significantly increased (p < .001 for all), and had no statistical difference compared with the non-BDDH hips (p = .193, p = .132, p = .421, respectively).

Conclusion

BDDH hips had a significantly higher prevalence of CAO than adequate acetabular coverage hips. After the procedure of CAD, BDDH hips were found to have acetabular parameters (CFW, CFH, CNW) and were restored to that of the control hips.

Discrepancy in the Distribution Patterns of Subchondral Bone Density Across the Ankle Joint After Medial Opening-Wedge and Lateral Closing-Wedge High Tibial Osteotomy

BACKGROUND

High tibial osteotomy (HTO) changes the alignment and dynamics of the ankle joint; however, differences in the stress distribution of the ankle joint after opening-wedge HTO (OWHTO) and closing-wedge HTO (CWHTO) are not understood. It is believed that subchondral bone density of the articular surface reflects the pattern of cumulative stress distribution across the joint surface.

PURPOSE

To clarify the effects of OWHTO and CWHTO on the distribution patterns of subchondral bone density across the ankle joint using computed tomography (CT)-osteoabsorptiometry.

STUDY DESIGN

Cohort study; Level of evidence, 4.

METHODS

Radiographic and CT data of 18 cases who underwent OWHTO (OW group), 12 cases who underwent CWHTO (CW group), and 11 cases with unilateral anterior cruciate ligament injury serving as controls were retrospectively reviewed. The subchondral bone density of the distal tibia was assessed in the 3 groups using CT-osteoabsorptiometry. The distal tibial surface of the ankle joint was divided into 4 parts in the coronal direction, and the percentage of the high-density area (%HDA) to each subregion was compared before and after HTO.

RESULTS

Preoperatively, comparing %HDA among the 3 groups, there were no significant differences in any regions. In the OW group, postoperative %HDA in the most medial region was significantly increased compared with preoperative %HDA (49.3% to 53.0%; P = .011), and postoperative %HDA in the most lateral region was significantly decreased (21.4% to 17.2%; P = .003). On the other hand, in the CW group, postoperative %HDA in the most medial region was significantly decreased (55.7% to 35.7%; P = .001), and %HDA in the second lateral region was significantly increased (23.6% to 29.2%; P = .002).

CONCLUSION

The ankle distribution pattern of subchondral bone density shifted significantly medially after OWHTO without fibular osteotomy, whereas the distribution pattern shifted laterally after CWHTO with fibular osteotomy. When the OWHTO is performed for patients with medial ankle osteoarthritis, surgeons should pay attention to potential postoperative progression of ankle osteoarthritis due to medial shift of the stress distribution in the ankle joint.

Effect of High Tibial Osteotomy on the Distribution of Subchondral Bone Density Across the Proximal Tibial Articular Surface of the Knee With Medial Compartment Osteoarthritis

BACKGROUND

The effect of high tibial osteotomy (HTO) on the stress distribution across the knee joint is not completely understood. Subchondral bone density is considered to reflect the pattern of stress distribution across a joint surface.

PURPOSE

To assess the distribution of subchondral bone density across the proximal tibia in nonarthritic knees and in the knees of patients with osteoarthritis (OA) before and after HTO.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

We retrospectively collected radiological and computed tomography data from 16 patients without OA (control group) and 17 patients with OA. Data from the OA group were collected before and 1.5 years after HTO. Subchondral bone density of the proximal tibia was assessed with computed tomography-osteoabsorptiometry. The locations and percentages represented by high-density areas (HDAs) on the articular surface were quantitatively analyzed.

RESULTS

The ratio of the HDA of the medial compartment to the total HDA (medial ratio) was significantly higher in the preoperative OA group (mean, 80.1%) than in the control group (61.3%) (P < .001). After HTO, the medial ratio decreased significantly to 75.1% (P = .035 in comparison with preoperative values) and was significantly correlated with the hip-knee-ankle angle in both groups: control (r = -0.551; P = .033) and OA (r = -0.528; P = .043). The change in medial ratio after HTO was significantly correlated with the change in hip-knee-ankle angle (r = 0.587; P = .035). In the medial compartment, the HDA in the most lateral region of 4 subregions increased after HTO, but that in 3 medial subregions decreased.

CONCLUSION

In this exploratory study, HTO shifted the HDA of the medial compartment of the proximal tibial articular surface toward the lateral compartment. In contrast, the HDA of the most lateral region of the medial compartment increased after HTO. This change in subchondral bone density may result from the change in stress distribution.

Long-term Stress Distribution Patterns Across the Ankle Joint in Soccer Players: A Computed Tomography Osteoabsorptiometry Study

Background:

The distribution pattern of subchondral bone density is considered to accurately reflect the stress distribution over a joint under long-term physiologic loading. The biomechanical characteristics of the surface of the ankle joint in soccer players can be determined by measuring this distribution pattern under long-term loading.

Purpose:

To evaluate the distribution of subchondral bone density across the ankle joint in soccer players and to determine the effects of soccer activities, including kicking motion, on the ankle joint surface under long-term loading conditions by computed tomography (CT) osteoabsorptiometry (CTOAM).

Study Design:

Cross-sectional study; Level of evidence, 3.

Methods:

CT imaging data were obtained from both ankles of 10 soccer players (soccer group) and 10 nonathletic volunteers (control group). The distribution patterns of subchondral bone density across the articular surface of the ankle joints were assessed by CTOAM. Quantitative analysis was performed of the locations and percentages of high-density areas on the articular surface.

Results:

Stress distribution patterns over the ankle joint differed between the soccer players and controls. In the soccer players, the high-density areas were found in the anterior part of the distal tibia and proximal talus as well as the distal fibula. The percentages of high-density areas were greater in the soccer players compared with controls (P < .0001).

Conclusion:

Stress distribution over the articular surface of the ankle joint was affected by soccer activities. A high stress concentration was seen in soccer players in the anterior part of the tibia and talus and in the fibula; such excessive stress may lead to anterior impingement.

Subchondral bone strength of the sacroiliac joint-a combined approach using computed tomography osteoabsorptiometry (CT-OAM) imaging and biomechanical validation

Bone mineral density distribution patterns at the sacroiliac joint (SIJ) may reflect long-term adaptation patterns to the loading the joint endures. This study aims to display bone mineralisation patterns of the articular SIJ subchondral lamella using computed tomography (CT) osteoabsorptiometry and mechanical indenting, to determine whether a relationship exists between mineralisation and mechanical strength. Twenty hemipelves were CT-scanned before osteoabsorptiometry densitograms were derived. Each articular side of eleven SIJs was mechanically indented following a 10-mm grid scheme. The sacral surface displayed lower Hounsfield unit (HU) values (≤ 700 HU) than the iliac side (> 700 HU). The apex, superior corner and borders yielded the highest HU scores (> 700 HU). Penetration strength was significantly higher on the iliac side (p < 0.04). Mineral density correlated positively with penetration strength of the subchondral bone layer (p < 0.05). No correlations were found between the HU values, nor between penetration strength of corresponding sides of the same SIJ in the majority of cases (p > 0.05). The iliac subchondral lamella is mechanically denser than the sacral aspect. The non-correlation between density and bone strength of articulating sides indicates biomechanical non-conformity. Loading throughout the SIJ may follow a complex distribution pattern involving the surrounding soft tissues, suspending the sacrum between the ilia.

In vivo kinematics, component alignment and hardware variables influence on the liner-to-neck clearance during chair-rising after total hip arthroplasty

BACKGROUND

There is an interest in quantifying dynamic hip kinematics before and after total hip arthroplasty (THA) during chair-rising: one of daily life activities.

METHODS

The study consisted of 21 patients who underwent unilateral total hip arthroplasty for symptomatic osteoarthritis. We obtained continuous radiographs using a flat-panel X-ray detector while the participants rose from chair. We assessed the pre and postoperative hip joint's movements using three-dimensional-to-two-dimensional model-to-image registration techniques. We also measured minimum liner-to-neck distances at maximum hip flexion and extension as anterior and posterior liner-to-neck distances, respectively. Multivariate analyses were applied to determine which factors were associated with liner-to-neck distances.

RESULTS

The cup inclination, cup anteversion, and stem anteversion averaged 37.4°, 23.1°, and 30.1°, respectively. Significantly larger maximum hip flexion angle (72°) was found during chair-rising after THA compared to that before THA (63°, P < 0.01). The anterior pelvic tilt at the maximum hip flexion after THA (3° of anterior tilt) was significantly (P < 0.05) anterior compared to that before THA (1° of posterior tilt). The anterior and posterior liner-to-neck distances averaged 12.3 mm and 8.1 mm, respectively, with a significant difference (P < 0.01). No liner-to-neck contact was found in any hips. In multivariate analysis, the hip flexion angle, cup inclination, stem anteversion and head diameter were significantly associated with the anterior liner-to-neck distance (P < 0.05), the hip extension angle, cup anteversion, neck length and with or without elevated rim were significantly associated with the posterior liner-to-neck distance (P < 0.05, 0.01, 0.05, 0.01, respectively).

CONCLUSION

This study indicates that well-positioned THA provide increased range of hip flexion with sufficient anterior liner-to-neck clearance during chair-rising. Dynamic hip kinematics, component position, and hardware variables significantly influenced on the liner-to-neck clearance under weight-bearing conditions.

Three-dimensional curvature mismatch of the acetabular radius to the femoral head radius is increased in borderline dysplastic hips

Whether borderline hip dysplasia is pathologic remains unclear. In order to evaluate the three-dimensional joint congruity, this study sought to answer the question: are borderline dysplastic hip curvature mismatch and eccentricity between the acetabulum and the femoral head different from dysplastic or control hips three-dimensionally? The 113 hips, categorized as: dysplastic (LCEA ≤ 20°), 47 hips; borderline (20° ≤ LCEA < 25°), 32 hips; and control (25° ≤ LCEA < 35°), 34 hips; were evaluated. Three-dimensional (3D) femoral and coxal bone models were reconstructed from CT images. Using a custom-written Visual C++ routine, the femoral head and acetabular radii of curvature, and the femoral head and the acetabular curvature center were calculated. Then the ratio of the acetabular radius to the femoral head radius (3D curvature mismatch ratio), and the distance between the acetabular curvature center and the femoral head center (3D center discrepancy distance) were calculated. These indices were compared statistically among the three groups using Tukey's post hoc test. The mean 3D curvature mismatch ratio in the borderline (1.13 ± 0.05) was smaller than in the dysplasia (1.23 ± 0.08, p < 0.001), and larger than in the control (1.07 ± 0.02, p < 0.001). The mean 3D center discrepancy distance in the borderline (3.2 ± 1.4 mm) was smaller than in the dysplasia (4.8 ± 2.3, p < 0.001) and larger than in the control (1.6 ± 0.7, p < 0.001). These results demonstrated that three-dimensional congruity of the borderline dysplastic hip is impaired, but its incongruity is not as severe as in dysplastic hips. The 3D curvature mismatch ratio and the 3D center discrepancy distance can be valuable signs of joint congruity in patients with borderline dysplasia. However, future studies are necessary to clarify any associations between curvature mismatch and pathogenesis of osteoarthritis in borderline dysplasia.

Clinical and radiographic predictors of failed hip arthroscopy in the management of dysplasia: a systematic review and proposal for classification

PURPOSE

As indications for hip arthroscopy continue to expand, its efficacy in patients with more complex deformities of the hip, such as those with acetabular dysplasia, remains controversial. The purpose of this systematic review is to identify the predictors of failed hip arthroscopy in dysplastic hips and to propose a standardize prognostic sub-classification of dysplasia.

METHODS

This systematic review was performed in accordance with the (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) PRISMA guidelines. Three databases [EMBASE, PubMed, and Ovid (MEDLINE)] were searched using terms including "hip arthroscopy" and "dysplasia". Studies were screened and data extracted in duplicate. Study quality was assessed using the Methodological Index for Non-Randomized Studies criteria. Due to the non-uniform nature of study data, findings were presented in descriptive summary form.

RESULTS

Thirteen studies were included in this systematic review, comprising 712 dysplastic patients (773 hips) with mean age 34.2 years and 74.1% females. Most studies defined hip dysplasia by a lateral centre-edge angle (LCEA) of 20°-25° (borderline) or 15°-20° (moderate). Failure was defined as progression to revision arthroscopy, peri-acetabular osteotomy, or total hip arthroplasty. Overall, failure rate was 192/743 (25.8%) at an average of 28.1 months following index arthroscopy. Smaller LCEA, larger Tönnis angle, broken Shenton line, and decreased joint space (≤ 2 mm) were radiographic predictors of failure. Severe cartilage lesions to the femoral head or acetabulum were associated with failure in five studies. Labral debridement led to more failures than labral repair.

CONCLUSION

Overall, hip arthroscopy yielded good outcomes in mildly dysplastic hips without severe chondral damage. Hip arthroscopy is expected to result in a failed outcome in individuals with moderate-to-severe hip dysplasia (LCEA < 15°), severe cartilage lesions, larger Tönnis angle (> 20°), broken Shenton line, and decreased joint space (≤ 2 mm). Arthroscopic surgery may be more effective in individuals with borderline-to-mild (LCEA 15°-25°) acetabular dysplasia in the absence of severe cartilaginous lesions (7-year survival: 89.6%). A standardized prognostic classification of hip dysplasia based on the LCEA and Tönnis angle is proposed.

LEVEL OF EVIDENCE

Systematic review of non-randomized studies, Level IV.

Dynamic hip kinematics before and after periacetabular osteotomy in patients with dysplasia

BACKGROUND

We prospectively analyzed the hip kinematics in patients with developmental dysplasia of the hip (DDH) before and after periacetabular osteotomy (PAO) and in healthy subjects while squatting to determine the influence of coverage of the femoral head on hip kinematics.

METHODS

14 hips in 14 patients with DDH and 10 hips in 10 volunteers were included. Continuous radiographs while squatting and computed tomography images were obtained to assess the in vivo kinematics of the hip and the rim-neck distance using density-based 3D-to-2D model-to-image registration techniques.

RESULTS

The maximum hip flexion angles were 100.4° and 94.9° before and after PAO (p = 0.0863), respectively. The maximum hip flexion angles after PAO did not significantly differ from those of normal hips (102.2°; p = 0.2552). The hip abduction angles at maximum hip flexion were 31.7° and 26.2° before and after PAO (p = 0.1256), respectively. The rim-neck distance decreased from averaged 12.2 mm-8.9 mm (p = 0.0044) after PAO. The lateral center edge angle (LCEA) and anterior center edge angle (ACEA) significantly improved 14.7°-42.4° and 50.4°-54.0° after PAO (p < 0.0001, p = 0.0347), respectively; in particular, the ACEA after PAO did not significantly differ from that in the normal hips (p = 0.1917). The ACEA was not correlated with hip flexion, or the rim-neck distance (p = 0.9601, 0.8764). The LCEA was also not correlated with hip abduction (p = 0.1683).

CONCLUSION

Patients after PAO showed no significant difference in maximum hip flexion while squatting compared to before PAO and normal hips. Horizontalized weight-bearing acetabulum with normalized ACEA could be adequate correction of the acetabular fragment to restore hip RoM without coxalgia that induce the inability to perform squats after PAO.

Acetabular Anatomical Parameters in Patients With Idiopathic Osteonecrosis of the Femoral Head

BACKGROUND

Osteonecrosis of the femoral head (ONFH) is an increasing worldwide health problem. However, about 30% of the patients are diagnosed with idiopathic ONFH, which means no underlying etiology is identified. We hypothesized that acetabular anatomical abnormalities might be related to idiopathic ONFH.

METHODS

This retrospective, 1:2 matched, case-control study included 101 patients (136 hips) with idiopathic ONFH and 202 control subjects (404 hips) matched for age, gender, and body mass index who had no apparent radiographic hip pathologies. The anteroposterior pelvic X-rays of the patients and control subjects were used to measure the anatomical parameters including the center-edge angle, the sharp angle, the acetabular depth ratio (ADR), and the acetabular head index (AHI).

RESULTS

We found that hips with idiopathic osteonecrosis had less acetabular coverage, lower center-edge angle (28.3° vs 32.3°, P < .001), acetabular depth ratio (298.0 vs 306.4, P = .006), and acetabular head index (82.2 vs 85.8, P < .001), and higher sharp angle (39.7° vs 38.0°, P < .001), compared with the control subjects. The incidence of acetabular dysplasia was also higher in the idiopathic ONFH group than the control group.

CONCLUSION

Less acetabular coverage was found in hips with idiopathic osteonecrosis than the control subjects. Less acetabular coverage may be associated with the development of ONFH in East Asian population.

Hip Arthroscopy of a Painful Hip with Borderline Dysplasia

Purpose

Hip arthroscopy has been considered for treating hip dysplasia; however, its efficacy is still a matter of controversy. Here, we report outcomes of patients with borderline dysplasia treated with a contemporary hip arthroscopy technique.

Materials and Methods

Forty-seven hips with borderline hip dysplasia were treated using hip arthroscopy. Patients underwent procedures to correct torn labrums or ligamentum teres with additional procedure on the acetabular capsule. Patient outcomes were assessed using visual analogue scale (VAS), modified Harris Hip Score (mHHS), Nonarthritic Hip Score (NAHS) and patient satisfaction. Risk factors for poor prognosis were also investigated.

Results

The mean follow up period was 25.9 months. At the last follow up, mean VAS score decreased from 6.1±1.6 to 3.5±2.8 (P=0.016). The mHHS and NHAS at the last follow up improved from 61.0±7.6 to 78.6±19.5 (P=0.001) and 62.1±7.5 to 80.0±18.5 (P=0.002), respectively. While significant improvement was observed in all patient reported outcome measures tested, 19 (40.4%) hips indicated that “the operation was unsatisfactory.” The only factor shown to influence outcomes was preoperative VAS (i.e., worse scores potentially an indicator of poor outcomes).

Conclusion

The results of the current study indicate that arthroscopic management may be beneficial for a subset of patients with borderline dysplasia; however, the dissatisfaction rate associated with this treatment approach may be as high as 40%. The poor preoperative pain score appears to be the sole indicator for poor outcomes.