Femoral head deformity and severity of acetabular dysplasia of the hip

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.

Midterm results after arthroscopic femoral neck osteoplasty combined with labral debridement for cam type femoroacetabular impingement in active adults

INTRODUCTION

Arthroscopic labral procedures are frequently undertaken in patients with femoroacetabular impingement (FAI). The role of arthroscopic femoral neck osteoplasty is well established, but less is known about labral procedures. This study evaluates the midterm efficacy and feasibility of arthroscopic osteoplasty with concomitant labral debridement for cam impingement in active adults.

METHODS

The present study was conducted according to the STROBE Statement. All 108 patients who underwent primary hip arthroscopy for cam type FAI combined with labral debridement were considered. Axial and anteroposterior plain radiographs of the pelvis were obtained preoperatively to identify the cam deformity and assess the presence of osteoarthritis, the lateral centre-edge angle, and the alpha angle. The ROM (flexion, extension, abduction, adduction, and intra/extra rotation) was evaluated. The following PROMs were administered: visual analogic scale (VAS), Tegner Activity Scale, non-arthritic hip score (NAHS), the international Hip Outcome Tool (iHOT-33) overall score, and related subscales: symptoms and functional limitations, sports and recreational activities, job-related concerns, and social, emotional, and lifestyle concerns.

RESULTS

At a mean of 2.0 ± 1.1 months, all 108 patients returned to their daily activities with no limitation. At a mean of 2.6 ± 1.4 months, all 108 patients were able to return to sport with no limitation. At 11.9 ± 2.1-month follow-up, no differences were reported in the range of motion compared to baseline: flexion (P = 0.3), extension (P = 0.09), abduction (P = 0.1), adduction (P = 0.3), internal rotation (P = 0.4), and external rotation (P = 0.6). At 72.8 ± 21.7-month follow-up, the mean VAS score was 1.7 ± 3.0, Tegner Activity Scale 3.5 ± 1.4, NAHS 92.1 ± 21.5, iHOT33 83.3 ± 27.2. At a mean of 21.7 ± 15.5 months following the index procedure, 14 of 108 patients had undergone total hip arthroplasty. No further revisions or complications were reported.

CONCLUSION

Arthroscopic femoral neck osteoplasty with concomitant labral debridement for cam type of FAI in active adults yields the reliable results, with a rate of progression to total hip arthroplasty of 13% (14 of 108) at 3-year follow-up. All patients returned to their daily activities with no limitation 2 months postoperatively. Within 3 months, all patients returned to sport with no limitations. No complication related to the index procedure was reported, and no further arthroscopic procedures were necessary.

Minimally Invasive Radiographic Evaluation of the Dysplastic Hip Joint Configuration in Terms of Surgical Treatment with Hip Preservation by PAO

Introduction

Residual developmental dysplasia of hip (RDDH) is a factor of early osteoarthritis of the hip. The main problems are pain and instability of the hip joint due to inadequate coverage of the femoral head by the acetabulum. The purpose of this study was to radiologically evaluate RDDH after Bernese periacetabular osteotomy (PAO) and to compare RDDH to healthy hips.

Materials and Methods

The radiological parameters of RDDH treated by PAO were retrospectively evaluated. Digital AP pelvic radiographs were taken, including parameters of central edge angle and femoral head coverage, medialization, distalization, and ilio-ischial angle. Clinical assessment is based on the VAS scale. The study group consisted of patients with RDDH, and the control group consisted of patients without RDDH.

Results

After PAO radiological parameters decreased: medialization by 2.68 mm, distalization by 3.65 mm, and ilio-ischial angle by 2.62°. However, there was an increase in the parameters: CEA by 17.61° and FHC by 16.46%. There was a mean 3 point decrease in pain on the VAS scale. There was also a statistically significant radiological difference in the structure of dysplastic hip joints before surgery and healthy hip joints of the control group.

Conclusions

Radiological studies confirmed the effectiveness of the PAO method in the treatment of RDDH. Based on all radiological parameters, differences between healthy and dysplastic hip joints were demonstrated. We believe that a thorough understanding of the values of radiological parameters used to describe dysplastic hip joints will allow us to improve the imaging diagnosis of this condition.

Factors Associated With Abnormal Joint Contact Pressure After Periacetabular Osteotomy: A Finite-Element Analysis

BACKGROUND

Identifying factors associated with poor hip contact mechanics after periacetabular osteotomy (PAO) may help surgeons optimize acetabular corrections in individual patients. We performed individual-specific finite-element analyses to identify preoperative morphological and surgical correction factors for abnormal contact pressure (CP) after PAO.

METHODS

We performed finite-element analyses before and after PAO with reference to the standing pelvic position on individual-specific 3-dimensional hip models created from computed tomography images of 51 dysplastic hips. Nonlinear contact analyses were performed to calculate the joint CP of the acetabular cartilage during a single-leg stance.

RESULTS

The maximum CP decreased in 50 hips (98.0%) after PAO compared to preoperative values, and the resulting maximum CP was within the normal range (<4.1 MPa) in 33 hips (64.7%). Multivariate analysis identified the roundness index of the femoral head (P = .002), postoperative anterior center-edge angle (CEA; P = .004), and surgical correction of lateral CEA (Δlateral CEA; P = .003) as independent predictors for abnormal CP after PAO. A preoperative roundness index >54.3°, a postoperative anterior CEA <36.3°, and a Δlateral CEA >27.0° in the standing pelvic position predicted abnormal CP after PAO.

CONCLUSION

PAO normalized joint CP in 64.7% of the patients but was less likely to normalize joint CP in patients with aspheric femoral heads. Successful surgical treatment depends on obtaining adequate anterior coverage and avoiding excessive lateral correction, while considering the physiological pelvic tilt in a weight-bearing position.

Effect of coronal plane acetabular correction on joint contact pressure in Periacetabular osteotomy: a finite-element analysis

Background

The ideal acetabular position for optimizing hip joint biomechanics in periacetabular osteotomy (PAO) remains unclear. We aimed to determine the relationship between acetabular correction in the coronal plane and joint contact pressure (CP) and identify morphological factors associated with residual abnormal CP after correction.

Methods

Using CT images from 44 patients with hip dysplasia, we performed three patterns of virtual PAOs on patient-specific 3D hip models; the acetabulum was rotated laterally to the lateral center-edge angles (LCEA) of 30°, 35°, and 40°. Finite-element analysis was used to calculate the CP of the acetabular cartilage during a single-leg stance.

Results

Coronal correction to the LCEA of 30° decreased the median maximum CP 0.5-fold compared to preoperatively (p <  0.001). Additional correction to the LCEA of 40° further decreased CP in 15 hips (34%) but conversely increased CP in 29 hips (66%). The increase in CP was associated with greater preoperative extrusion index (p = 0.030) and roundness index (p = 0.038). Overall, virtual PAO failed to normalize CP in 11 hips (25%), and a small anterior wall index (p = 0.049) and a large roundness index (p = 0.003) were associated with residual abnormal CP.

Conclusions

The degree of acetabular correction in the coronal plane where CP is minimized varied among patients. Coronal plane correction alone failed to normalize CP in 25% of patients in this study. In patients with an anterior acetabular deficiency (anterior wall index < 0.21) and an aspherical femoral head (roundness index > 53.2%), coronal plane correction alone may not normalize CP. Further studies are needed to clarify the effectiveness of multiplanar correction, including in the sagittal and axial planes, in optimizing the hip joint’s contact mechanics.

Novel model for the induction of postnatal murine hip deformity

Acetabular dysplasia is a common, multi-etiological, pre-osteoarthritic (OA) feature that can lead to pain and instability of the young adult hip. Despite the clinical significance of acetabular dysplasia, there is a paucity of small animal models to investigate structural and functional changes that mediate morphology of the dysplastic hip and drive the subsequent OA cascade. Utilizing a novel murine model developed in our laboratory, this study investigated the role of surgically induced unilateral instability of the postnatal hip on the initiation and progression of acetabular dysplasia and impingement up to 8-weeks post-injury. C57BL6 mice were used to develop titrated levels of hip instability (i.e., mild, moderate, and severe instabillity or femoral head resection) at weaning. Joint shape, acetabular coverage, histomorphology, and statistical shape modeling were used to assess quality of the hip following 8 weeks of destabilization. Acetabular coverage was reduced following severe, but not moderate, instability. Moderate instability induced lateralization of the femur without dislocation, whereas severe instability led to complete dislocation and pseudoacetabulae formation. Mild instability did not result in morphological changes to the hip. Removal of the femoral head led to reduced hip joint space volume. These data support the notion that hip instability, driven by mechanical loss-of-function of soft connective tissue, can induce morphometric changes in the growing mouse hip. This work developed a new mouse model to study hip health in the murine adolescent hip and is a useful tool for investigating the mechanical and structural adaptations to hip instability during growth. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.

Minimum 10-Year Clinical Outcomes After Periacetabular Osteotomy for Advanced Osteoarthritis Due to Hip Dysplasia

The purpose of this study was to examine the minimum 10-year clinical outcomes, including patient-reported and functional outcomes, of periacetabular osteotomy in patients with advanced osteoarthritis. A total of 46 hips in 44 patients with advanced osteoarthritis who underwent periacetabular osteotomy between 1992 and 2006 were retrospectively reviewed. Mean age at surgery was 47.5 years, and mean follow-up was 16.9±4.7 years. Survivorship was determined using the Kaplan-Meier method, and the associated risk factors for the endpoint-conversion to total hip arthroplasty less than 15 years after surgery-were evaluated. The Oxford Hip Score and the University of California, Los Angeles activity score were evaluated at final follow-up. The survival rates at 15 and 20 years after surgery were 80% and 59%, respectively. Multivariate analysis indicated that body mass index greater than 24 kg/m² (P=.034; odds ratio, 1.72) was significantly associated with the endpoint as an independent risk factor. For 32 hips of 31 patients with preserved native joints at final follow-up, the Oxford Hip Score and the University of California, Los Angeles score averaged 41±5 and 5.2±1.8, respectively, equivalent (P=.28 and P=.215, respectively) to the scores of 14 hips of 13 patients with conversion to total hip arthroplasty (38±8.7 and 5.8±1.4, respectively). The results of this mid-term study may be useful for surgical decision-making among patients with advanced osteoarthritis who want to preserve native hip joints. [Orthopedics. 2018; 41(5):300-305.].

Three-dimensional MRI analyses of prereduced femoral head sphericity in patients with developmental dysplasia of the hip after Pavlik harness failure

We used three-dimensional (3D) MRI to assess the sphericity of the cartilaginous femoral head in developmental dysplasia of the hip. We assessed 21 children using 3D-MRI. The smallest sphere including the femoral head cartilage was drawn, the diameter was measured, and the center of the sphere was defined. We compared the diameters of the femoral heads between unaffected and diseased sides. The diameter of the affected side was smaller, with flattening at the posteromedial area and proximoposterior areas. 3D-MRI showed that the shape of the dislocated femoral head was aspherical with focal growth failure.

Changes in femoral head size and growth rate in young children with severe developmental dysplasia of the hip

BACKGROUND

Developmental dysplasia of the hip (DDH) is known to result in smaller femoral head size in toddlers; however, alterations in femoral head size and growth have not been documented in infants.

OBJECTIVE

To determine with ultrasound (US) whether femoral head size and growth are altered in infants (younger than 1 year of age) with severe DDH.

MATERIALS AND METHODS

We identified all patients at our tertiary care children's hospital from 2002 to 2014 who underwent US for DDH. We included studies with at least one hip with severe DDH, defined as <25% coverage of the femoral head, and excluded teratological DDH. We constructed a control group of randomized patients with normal US studies. Two pediatric radiologists blinded to diagnosis measured bilateral femoral head diameter. Inter-reader variability and femoral head diameter difference between dislocated and contralateral normal femoral heads were evaluated. Mean femoral head diameters were compared across types of hip joint; femoral head growth rates per month were calculated.

RESULTS

Thirty-seven children with DDH (28 female) were identified (median age: 33 days). The control group contained 75 children (47 female) with a median age of 47 days. Fifty-three of the 74 hips in the study group had severe DDH. Twenty-four children with DDH had completely dislocated hips (nine bilateral, five with contralateral severe subluxations). Thirteen other children had severe subluxation, two bilaterally. There was good inter-reader agreement in the normal femoral head group and moderate agreement in the severe DDH group. In the study group, severe DDH femoral head diameter was significantly smaller than their contralateral normal hip. Severe DDH femoral head diameter was significantly smaller than normal femoral head diameter in the control group. The severe DDH femoral head growth rate was slightly less but not significantly slower than normal femoral head growth rate in the study group.

CONCLUSION

On US during infancy, femoral head size is significantly reduced in severe cases of DDH.

Obstacles to reduction in infantile developmental dysplasia of the hip

PURPOSE

Identification of anatomical structures that block -reduction in developmental dysplasia of the hip (DDH) is -important for the management of this challenging condition. Obstacles to reduction seen on arthrogram are well-known. However, despite the increasing use of MRI in the assessment of adequacy of reduction in DDH, the interpretation of MRI patho-anatomy is ill-defined with a lack of relevant literature to guide clinicians.

METHOD

This is a retrospective analysis of the MRI of patients with DDH treated by closed reduction over a five-year period (between 2009 and 2014). Neuromuscular and genetic disorders were excluded. Each MRI was analysed by two orthopaedic surgeons and a paediatric musculoskeletal radiologist to identify the ligamentum teres, pulvinar, transverse acetabular ligament (TAL), capsule, labrum and acetabular roof cartilage hypertrophy. Inter- and intraobserver reliability was calculated. The minimum follow-up was 12 months.

RESULTS

A total of 29 patients (38 hips) underwent closed reduction for treatment of DDH. Eight hips showed persistent subluxation on post-operative MRI. Only three of these eight hips showed an abnormality on arthrogram. The pulvinar was frequently interpreted as 'abnormal' on MRI. The main obstacles identified on MRI were the ligamentum teres (15.8%), labrum (13.1%) and acetabular roof cartilage hypertrophy (13.2%). The inter-rater reliability was good for TAL, capsule and pulvinar; moderate for ligamentum teres and labrum; and poor for hypertrophied cartilage.

CONCLUSION

The labrum, ligamentum teres and acetabular roof cartilage hypertrophy are the most important structures seen on MRI preventing complete reduction of DDH. Focused interpretation of these structures may assist in the management of DDH.

What factors predict the failure of curved intertrochanteric varus osteotomy for the osteonecrosis of the femoral head?

INTRODUCTION

The purpose of this study was to examine the 10-year survivorship and clinical outcome after curved intertrochanteric varus osteotomy (CVO) for the osteonecrosis of the femoral head (ONFH), and to determine what factors predict the failure of this procedure.

MATERIALS AND METHODS

We retrospectively reviewed 102 consecutive CVOs in 93 patients diagnosed with ONFH. Mean follow-up duration was 10.1 years (3.0-23.2 years). Factors associated with radiographic failure (secondary collapse and/or osteoarthritic change), conversion to total hip arthroplasty (THA) and low Harris Hip Score (HHS), were assessed. The Kaplan-Meier method was used to estimate survival rate.

RESULTS

Radiographic failure occurred in 27 hips (26.5 %), and 11 hips (10.8 %) were converted to THA. The 10-year survival rate was 91.0 % [95 % confidence interval (CI) 83.4-95.2 %] with conversion to THA as the endpoint and 72.4 % (95 % CI 62.3-80.3 %) with radiographic failure as the endpoint. Mean HHS improved from 70.0 preoperatively to 88.1 at the final follow-up (p < 0.001). Multivariate Cox regression analysis showed that postoperative intact ratio <33.3 % [hazard ratio (HR), 11.17; 95 % CI 4.14-30.14] and center-edge (CE) angle <25° (HR 4.91; 95 % CI 1.92-12.55) were independent factors determining radiographic failure. In addition, the multivariate Cox regression analysis showed that postoperative intact ratio <33.3 % (HR 10.65; 95 % CI 2.24-50.53) and CE angle <25° (HR 7.81; 95 % CI 2.17-28.07) were also factors determining conversion to THA. Worse HHSs of <80 were seen in patients with postoperative intact ratio <33.3 % (p < 0.001), CE angle <25° (p < 0.001), and acetabular head index <75 % (p = 0.006).

CONCLUSIONS

Postoperative intact ratio <33.3 % and CE angle <25° were identified as independent factors determining radiographic failure and conversion to THA. Therefore, these factors must be taken into consideration when selecting patients for CVO.

Femoral Morphology in Patients Undergoing Periacetabular Osteotomy for Classic or Borderline Acetabular Dysplasia: Are Cam Deformities Common?

BACKGROUND

The primary purpose of our study was to determine the prevalence of Cam deformity in patients with symptomatic acetabular dysplasia (SAD) who underwent periacetabular osteotomy (PAO).

METHODS

We retrospectively reviewed 164 SAD PAO patients from 2 institutions. Preoperative anteroposterior and frog-lateral radiographs were analyzed for lateral center edge angle (LCEA), retroversion, alpha angles, and anterior femoral head-neck offset. Hips were classified as dysplastic (LCEA <20°, group A, n = 142) and borderline dysplastic (LCEA 20°-25°, group B, n = 22). There were 128 females and 36 males with an average age of 29 years (range 13-56).

RESULTS

The overall prevalence of Cam deformity was 10% (17 of 164) in SAD patients. There was no difference in the prevalence of Cam deformity between the groups (P > .99).

CONCLUSION

Prevalence of Cam deformities in our series of SAD patients having undergone PAO is less than prior reports. Careful radiographic measurement should be performed to avoid overtreating these hips with unnecessary osteochondroplasty procedures.

Effect of centre-edge angle on clinical and quality of life outcomes after arthroscopic acetabular labral debridement

PURPOSE

The aim of this study was to compare clinical and quality of life outcomes following arthroscopic acetabular labral debridement between patients with different centre-edge (CE) angle.

METHODS

A total of 79 patients who underwent hip labral debridement were enrolled in this study. Radiographic measurements of CE angle were collected, and patients were assigned into a normal group (25° < CE angle <40°, n = 68) and dysplasia group (CE angle <20°, n = 11). Clinical outcomes were evaluated by modified Harris Hip Score (mHHS), Hip Outcome Score (HOS) for activities of daily living (ADL) and sports and Short Form 12 (SF-12).

RESULTS

At the final follow-up, the normal group showed significant improvements in mHHS, HOS (ADL and sports) and SF-12 (P < 0.05). However, the dysplasia group revealed significant improvements in mHHS, HOS (ADL) and SF-12 physical component summary (PCS) (P < 0.05) and no significant changes in HOS sports and SF-12 mental component summary (MCS) (P > 0.05). Additionally, there was a greater improvement in clinical scores post-operatively in the normal group compared with the dysplasia group (P < 0.05).

CONCLUSIONS

Arthroscopic acetabular labral debridement resulted in significantly greater clinical and quality of life outcomes in patients with CE angle >25° compared with patients with CE angle < 20°.

The role of femoral neck anteversion in the development of osteoarthritis in dysplastic hips

There have been several studies examining the association between the morphological characteristics seen in acetabular dysplasia and the incidence of the osteoarthritis (OA). However, most studies focus mainly on acetabular morphological analysis, and few studies have scrutinised the effect of femoral morphology. In this study we enrolled 36 patients with bilateral acetabular dysplasia and early or mid-stage OA in one hip and no OA in the contralateral hip. CT scans were performed from the iliac crest to 2 cm inferior to the tibial tuberosity, and the morphological characteristics of both acetabulum and femur were studied. In addition, 200 hips in 100 healthy volunteer Chinese adults formed a control group. The results showed that the dysplastic group with OA had a significantly larger femoral neck anteversion and a significantly shorter abductor lever arm than both the dysplastic group without OA and the controls. Femoral neck anteversion had a significant negative correlation with the length of the abductor lever arm and we conclude that it may contribute to the development of OA in dysplastic hips.