What Are the Results of Surgical Treatment of Hip Dysplasia With Concomitant Cam Deformity?

Femurs in patients with hip dysplasia have fundamental shape differences compared with cam femoroacetabular impingement

Femoral deformities are common in developmental dysplasia of the hip (DDH), but decisions about how to treat them are not standardized. Of interest are deformities that may be akin to cam femoroacetabular impingement (FAI). We used three-dimensional and two-dimensional measures to clarify the similarities and differences in proximal femur shape variation among female patients with DDH (n = 68) or cam FAI (n = 60). Three-dimensional measures included femoral head asphericity, as well as shape variation using statistical shape modeling and principal component analysis (PCA). Two-dimensional measures included the α-angle, head-neck offset (HNO) and the neck-shaft angle (NSA). Significant shape variations were captured in the first five PCA modes, with the greatest shared variation between groups being the length from the lesser trochanter to the femoral head and greater trochanter height. Variations unique to DDH were irregularities at different areas of the femoral head, but not at the lateral femoral head-neck junction where variation was strong in FAI. The FAI group also had unique variations in greater trochanter shape. DDH femoral heads were less spherical, as indicated by larger sphere-fitting errors (P < 0.001). Radiographically, the DDH group had significantly smaller α-angles (P < 0.001), larger head-neck offsets (P = 0.02) and larger NSAs (P < 0.001). Both the articular and extra-articular regions of the proximal femur have distinct shape features in DDH and cam FAI that can uniquely affect the biomechanics of each disorder. Accordingly, approaches to addressing each disorder should be unique.

Pain, function and quality of life are impaired in adults undergoing periacetabular osteotomy (PAO) for hip dysplasia: a systematic review and meta-analysis

BACKGROUND

Hip dysplasia is a common condition in active adults with hip pain that can lead to joint degeneration. Periacetabular osteotomy (PAO) is a common surgical treatment for hip dysplasia. The effect of this surgery on pain, function and quality of life (QOL) has not been systematically analysed.

PURPOSE

In adults with hip dysplasia: (1) evaluate differences in pain, function and QOL in those undergoing PAO and healthy controls; (2) evaluate pre- to post-PAO changes in pain, function and QOL; (3) evaluate differences in pain, function and QOL in those with mild versus severe dysplasia, undergoing PAO; and (4) evaluate differences in pain, function and QOL in those having primary PAO versus those with previous hip arthroscopy.

METHODS

A comprehensive, reproducible search strategy was performed on 5 different databases. We included studies that assessed pain, function and QOL in adults undergoing PAO for hip dysplasia, using hip-specific patient reported outcomes measures.

RESULTS

From 5017 titles and abstracts screened, 62 studies were included. Meta-analysis showed PAO patients had worse outcomes pre- and post-PAO compared to healthy participants. Specifically, pain (standardised mean difference [SMD] 95% confidence interval [CI]): -4.05; -4.78 to -3.32), function (-2.81; -3.89 to -1.74), and QOL (-4.10; -4.43 to -3.77) were significantly poorer preoperatively.Meta-analysis found patients experienced improvements following PAO. Pain improved from pre-surgery to 1-year (standardised paired difference [SPD] 1.35; 95% CI, 1.02-1.67) and 2 years postoperatively (1.35; 1.16-1.54). For function, the activities of daily living scores at 1 year (1.22; 1.09-1.35) and 2 years (1.06; 0.9-1.22) and QOL at 1 year (1.36; 1.22-1.5) and 2 years (1.3; 1.1-1.5) all improved. No difference was found between patients undergoing PAO with mild versus severe dysplasia.

CONCLUSIONS

Before undergoing PAO surgery, adults with hip dysplasia have worse levels of pain, function and QOL compared to healthy participants. These levels improve following PAO, but do not reach the same level as their healthy participants.

REGISTRATION

PROSPERO (CRD42020144748).

[Hip dysplasia: What influence do age, arthrosis and concomitant diseases have on the treatment result?]

Pelvic osteotomies are an established treatment for symptomatic adult hip dysplasia with a promising long-term outcome. Results depend not only on the achieved acetabular reorientation but also on patient-factors like preoperative joint condition (degree of osteoarthritis and joint congruency) and age. Additionally, the diagnosis and appropriate therapy of impingement-associated hip deformities is essential in order to achieve good mid- and long-term outcomes. The influence of chondrolabral pathology on the outcome of pelvic osteotomies is not yet defined. Symptomatic patients with residual dysplasia after previous pelvic or acetabular osteotomies can benefit from an additional osteotomy, although results can be worse in comparison to prior unoperated joints. Obesity can make surgery more demanding and increases the complication profile of PAO, although it has no influence on the postoperative outcome. Regarding the overall prognosis after an osteotomy, the consideration of combined risk factors is superior to the concentration on individual factors alone.

Patient-Reported Outcomes are Similar in the First Two Years after Staged versus Combined Hip Arthroscopy and Periacetabular Osteotomy for Hip Dysplasia

PURPOSE

The purpose of this study was to compare early patient reported outcomes after staged versus combined hip arthroscopy and periacetabular osteotomy for hip dysplasia.

METHODS

A prospective database was retrospectively reviewed to identify patients that underwent combined or staged hip arthroscopy and PAO from 2012-2020. Patients were excluded if they were >40 years of age, had prior ipsilateral hip surgery, or did not have at least 12-24 month postoperative PRO data. PROs included the Hip Outcomes Score (HOS) Activities of Daily Living (ADL) and Sports Subscale (SS), Non-Arthritic Hip Score (NAHS), and the Modified Harris Hip Score (mHHS). Paired t-tests were used to compare preoperative to postoperative scores for both groups. Outcomes were compared using linear regression adjusted for baseline characteristics including age, obesity, cartilage damage, acetabular index, and procedure timing (early vs. late practice).

RESULTS

Sixty-two hips were included in this analysis (39 combined, 23 staged). The average length of follow up was similar between the combined and staged groups (20.8 vs. 19.6 months, p=0.192). Both groups reported significant improvements in PROs at final follow up compared to preoperative scores (p<0.05 for all). There were no significant differences in HOS-ADL, HOS-SS, NAHS, or mHHS scores between groups preoperatively or at 3, 6, or 12 months postoperatively (p>0.05 for all). There was no significant difference in PROs between the combined and staged groups at the final postoperative time point: HOS-ADL (84.5 vs. 84.3, p=0.77), HOS-SS (76.0 vs. 79.2, p=0.68), NAHS (82.2 vs. 84.5, p=0.79), mHHS (71.0 vs. 71.0, p=0.75) respectively.

CONCLUSION

Staged hip arthroscopy and PAO for hip dysplasia leads to similar PROs at 12-24 months compared to combined procedures. This suggests that with careful and informed patient selection, staging these procedures is an acceptable option for these patients and does not change early outcomes.

LEVEL OF EVIDENCE

Level III Retrospective Comparative.

Physical impairments in Adults with Developmental Dysplasia of the Hip (DDH) undergoing Periacetabular osteotomy (PAO): A Systematic Review and Meta-Analysis

Background

Developmental dysplasia of the hip (DDH) is a condition associated with hip pain and impairments. Periacetabular osteotomy (PAO) is a common surgical treatment for DDH. Outcomes following PAO have historically been based on radiology or patient reported outcomes, and not physical impairments.

Objective

To investigate differences in physical impairments in adults with DDH undergoing PAO compared with asymptomatic participants, and to investigate pre- to post-PAO changes in physical impairments.

Design

Systematic review with meta-analysis.

Methods

A literature search was performed in five databases (MEDLINE, CINAHL, EMBASE, Sports Discuss, and PsychINFO), using the PRISMA checklist. Studies were considered eligible if patients were aged 15 years and older, treated with PAO for DDH and if they included a physical impairment outcome measure. Two independent reviewers performed data extraction and assessed methodological quality, using a modified version of the Downs and Black checklist.

Results

Of 5,017 studies, 24 studies were included with 2190 patients. The methodological quality scores ranged from 39% to 88%. With low level of evidence, meta-analysis showed 58% of patients had a positive anterior impingement test (95%CI: 39-76%), prior to PAO and one to three years after PAO. Five years after PAO, the proportion fell to 17% (95%CI: 11-24%). Prior to PAO, patients with DDH walked with a lower peak hip extension angle, compared to asymptomatic participants (SMD 0.65 (95%CI 0.21-1.10). Best evidence synthesis of non-pooled data showed limited evidence of increased walking velocity, stride length and improved hip flexion and extension moment 18-months post-PAO compared to pre-op. Cadence, hip abduction and hip flexion strength did not change.

Conclusion

Most patients with DDH have a positive hip impingement test, pre-PAO. Compared to asymptomatic participants, patients with DDH demonstrate physical impairments during walking which appear to improve after surgery. Hip abduction and flexion strength did not change pre- to post-PAO.

Level of Evidence

1b.

Effect of modeling femoral version and head-neck offset correction on computed contact mechanics in dysplastic hips treated with periacetabular osteotomy

While correction of dysplastic acetabular deformity has been a focus of both clinical treatment and research, concurrent femoral deformities have only more recently received serious attention. The purpose of this study was to determine how including abnormalities in femoral head-neck offset and femoral version alter computationally derived contact stresses in patients with combined dysplasia and femoroacetabular impingement (FAI). Hip models with patient-specific bony anatomy were created from preoperative and postoperative CT scans of 20 hips treated with periacetabular osteotomy and femoral osteochondroplasty. To simulate performing only a PAO, a third model was created combining each patient's postoperative pelvis and preoperative femur geometry. These three models were initialized with the femur in two starting orientations: (1) standardized template orientation, and (2) using patient-specific anatomic landmarks. Hip contact stresses were computed in all 6 model sets during an average dysplastic gait cycle, an average FAI gait cycle, and an average stand-to-sit activity using discrete element analysis. No significant differences in peak contact stress (p = 0.190 to 1), mean contact stress (p = 0.273 to 1), or mean contact area (p = 0.050 to 1) were identified during any loading activity based on femoral alignment technique or inclusion of femoral osteochondroplasty. These findings suggest that presence of abnormal femoral version and/or head-neck offset deformities are not themselves predominant factors in intra-articular contact mechanics during gait and stand-to-sit activities. Inclusion of modified movement patterns caused by these femoral deformities may be necessary for models to adequately capture the mechanical effects of these clinically recognized risk factors for negative outcomes.

A comparison of 6-month outcomes between periacetabular osteotomy with concomitant hip arthroscopy to isolated hip arthroscopy for femoroacetabular impingement

PURPOSE

To compare early outcomes of periacetabular osteotomy (PAO) with concomitant hip arthroscopy to isolated hip arthroscopy for femoroacetabular impingement (FAI) and chondrolabral pathology using patient-reported outcomes measurement information system (PROMIS).

MATERIALS AND METHODS

Consecutive patients scheduled for PAO with concomitant hip arthroscopy (PAO + HA) or isolated hip arthroscopy (HA) between the ages of 15 and 30 years old were prospectively included in the study. Based on power analysis, subjects were recruited until there were 22 subjects in the PAO + HA group. These subjects were then gender matched to the HA group. The PROMIS, with six subscales and two global health measures, were completed during preoperative and 6-month follow-up visits. One-way ANOVA was performed to compare intake information of age, symptom duration, body mass index, and Beighton scores as well as preoperative and 6-month postoperative PROMIS scores between the PAO + HA and HA.

RESULTS

22 consecutive subjects undergoing PAO + HA were all females (average age 20.0 years) and matched to 22 consecutive females (average age 22.6) in the HA group. ANOVA did not find a significant difference between the two groups when comparing intact information, with exception of age (p = 0.04). A significant difference was also not identified (p ≥ 0.05) between the two groups on preoperative or 6-month postoperative PROMIS scores. The largest difference in 6-month postoperative scores between the two groups was 4.4 points on physical function subscale.

CONCLUSION

Outcomes at 6 months were not significantly different when comparing PAO + HA to HA for FAI and chondrolabral pathology in females under 30 years of age. The more extensive surgery with a prolonged protective period associated with PAO do not seem to negatively impact outcomes at 6 months when compared to HA. These finding support the use of PAO + HA, particularly if the patient and/or surgeon were concerned about prolonged disability, metal health issues, and/or higher pain levels that might be associated with the PAO procedure.

Endoscopic Shelf Procedure and Ischiofemoral Decompression with Arthroscopic Acetabular Labral Reconstruction: A Case Report

CASE

A 43-year-old female patient complained of pain in the right hip. The diagnoses of hip dysplasia, ischiofemoral impingement (IFI), femoroacetabular (FAI) cam-type morphology, and labral tear were made. The patient underwent hip arthroscopy with labral reconstruction for an irreparable labral tear and cam-morphology correction, and hip endoscopy for shelf procedure and ischiofemoral decompression. Favorable outcomes were reported at 1-year follow-up.

CONCLUSION

Hip arthroscopy for FAI cam-type morphology with labral reconstruction and concomitant hip endoscopy for shelf and ischiofemoral decompression seem to be safe for the treatment of active young adult patients with FAI cam-type morphology, irreparable labral tear, dysplasia, and IFI diagnoses. Nevertheless, the results presented should not be extrapolated as this is a case report.

Tönnis Grade 1 dysplastic hips have improved patient-reported outcome scores when intraarticular pathology is treated during periacetabular osteotomy

It is unclear whether treatment of intraarticular pathology should be performed during periacetabular osteotomy (PAO) to improve outcomes. Therefore, we asked: (i) What are the clinical results of PAO in patients with and without intraarticular intervention? (ii) Is there a difference in reoperations with and without intraarticular intervention? and (iii) Is there a difference in clinical results and reoperations depending on preoperative Tönnis Grade if intraarticular intervention is performed? Prospective evaluation of 161 PAO in 146 patients was performed. The cohort was 84.5% female, mean age was 26.7 ± 7.9 years and mean follow-up was 2.4 years; 112 hips had Grade 0 changes and 49 hips had Grade 1 changes. Patients were classified into three groups based on treatments during PAO: major (labral repair, femoral head–neck osteochondroplasty), minor (labral debridement, femoral/acetabular chondroplasty) or no intervention. A subset of eight patient-reported outcome measures (PROMs) was analyzed to determine whether the minimal clinically important difference (MCID) was achieved. Major, minor and no intervention groups exceeded the MCID in 5, 8 and 8, of 8 PROMs (P ≥ 0.20), respectively; intraarticular interventions did not influence reoperation-free survival (P ≥ 0.35). By Tönnis Grade, PROMs exceeding MCID decreased in Grade 1 versus 0 receiving no intervention (P &lt; 0.001) but did not decrease for either intervention (P ≥ 0.14); intraarticular interventions did not influence reoperation-free survival (P ≥ 0.38). Overall, intraarticular intervention was associated with excellent PROMs and reoperation-free survival. Although Grade 1 patients had fewer PROM which achieved MCID, intraarticular interventions attenuated this decrease, suggesting a therapeutic advantage of intraarticular procedures for more advanced pathology.

Short-term patient-reported outcomes following concomitant hip arthroscopy and the endoscopic modified shelf procedure for the treatment of acetabular dysplasia and intra-articular pathology

The shelf procedure is a treatment of acetabular dysplasia, with the aim of increasing weight-bearing acetabular coverage. Although several shelf techniques have been described, the endoscopic procedure with concomitant hip arthroscopy is a new, less invasive alternative. Outcomes following this procedure are scarce. The purpose of this study was to report short-term patient-reported outcomes (PROs) following concomitant hip arthroscopy and endoscopic modified shelf procedure in the setting of acetabular dysplasia and labral tears. Patients that met extraordinarily selective surgical indications and underwent the abovementioned surgery between February 2016 and October 2019 and had minimum 1-year follow-up were included. There were five females with a mean age of 40.18 ± 5.05 years and follow-up of 21.55 ± 8.68 months. The lateral center-edge angle increased from 15.80° to 23.20° (P = 0.003), and vertical center-edge angle increased from 16.60° to 23.60° (P < 0.001). The Tönnis angle decreased from 15.40° to 3.74° (P < 0.001). The alpha angle decreased from 58.46° to 40.70° (P < 0.001). PROs demonstrated significant improvement at latest follow-up (modified Harris Hip Score, P = 0.042; Non-Arthritic Hip Score, P < 0.001; Hip Outcome Score–Sports Specific Subscale, P = 0.035; Visual Analog Scale, P < 0.001; International Hip Outcome Tool-12, P = 0.043), and satisfaction was 8.60 ± 0.89. No secondary surgeries were reported. Concomitant hip arthroscopy and endoscopic modified shelf procedure appears to be a safe and effective procedure for patients with acetabular dysplasia and labral tears yielding favorable outcomes and satisfaction at short-term follow-up.

Acetabular- and femoral orientation after periacetabular osteotomy as a predictor for outcome and osteoarthritis

BACKGROUND

Periacetabular osteotomy is a successful treatment for hip dysplasia. The results are influenced, however, by optimal positioning of the acetabular fragment, femoral head morphology and maybe even femoral version as well as combined anteversion have an impact. In order to obtain better insight on fragment placement, postoperative acetabular orientation and femoral morphology were evaluated in a midterm follow-up in regard to functional outcome and osteoarthritis progression.

METHODS

A follow-up examination with 49 prospectively documented patients (66 hips) after periacetabular osteotomy (PAO) was performed after 62.2 ± 18.6 months. Mean age of patients undergoing surgery was 26.7 ± 9.6 years, 40 (82%) of these patients were female. All patients were evaluated with an a.p. pelvic x-ray and an isotropic MRI in order to assess acetabular version, femoral head cover, alpha angle, femoral torsion and combined anteversion. The acetabular version was measured at the femoral head center as well as 0.5 cm below and 0.5 and 1 cm above the femoral head center and in addition seven modified acetabular sector angles were determined. Femoral torsion was assessed in an oblique view of the femoral neck. The combined acetabular and femoral version was calculated as well. To evaluate the clinical outcome the pre- and postoperative WOMAC score as well as postoperative Oxford Hip Score and Global Treatment Outcome were analyzed.

RESULTS

After PAO acetabular version at the femoral head center (31.4 ± 9.6°) was increased, the anterior cover at the 15 o'clock position (34.7 ± 15.4°) was reduced and both correlated significantly with progression of osteoarthritis, although not with the functional outcome. Combined acetabular and femoral torsion had no influence on the progression of osteoarthritis or outcome scores.

CONCLUSION

Long-term results after PAO are dependent on good positioning of the acetabular fragment in all 3 planes. Next to a good lateral coverage a balanced horizontal alignment without iatrogenic pincer impingement due to acetabular retroversion, or insufficient coverage of the anterior femoral head is important.

Hitting the Target: Natural History of the Hip Based on Achieving an Acetabular Safe Zone Following Periacetabular Osteotomy

BACKGROUND

Periacetabular osteotomy (PAO) remains the gold-standard treatment for acetabular dysplasia in skeletally mature patients with preserved cartilage. The purpose of this multicenter cohort study was to delineate the long-term radiographic natural history of the dysplastic hip following PAO based on the final position of the acetabular fragment.

METHODS

We evaluated patients who underwent PAO performed by 4 hip preservation surgeons to treat acetabular dysplasia with or without concomitant retroversion from 1996 to 2012 at 3 academic institutions. There were 288 patients with a mean clinical and radiographic follow-up of 9 years (range, 5 to 21 years). Postoperative radiographs made at the first clinical visit were used to determine if the acetabular fragment fell into a safe zone according to the absence of retroversion, a lateral center-edge angle (LCEA) of 25° to 40°, an anterior center-edge angle (ACEA) of 25° to 40°, and a Tönnis angle of 0° to 10°. Every available subsequent radiograph was assessed for degenerative changes by the Tönnis classification (grades 0 to 3). The time to progression was analyzed using Cox proportional hazards regression and multistate modeling.

RESULTS

Only the absence of retroversion was independently associated with a decreased risk of progressing at least 1 Tönnis grade during follow-up: hazard ratio (HR), 0.60 (95% confidence interval [CI], 0.38 to 0.94; p = 0.025). Achieving the ACEA safe zone yielded the greatest time increase for remaining in Tönnis grade 0 or 1 (43 years for having an ACEA in the safe zone compared with 28 years for not having an ACEA in the safe zone), followed by the absence of retroversion (34 years for the absence of retroversion compared with 24 years for the presence of retroversion). However, attaining the Tönnis angle or LCEA safe zones did not delay progression. The achievement of additional safe zones generally increased the length of time that patients spent in Tönnis grade 0 or 1: 25 years for 0 safe zones, 36 years for 1 safe zone, 29 years for 2 safe zones, 37 years for 3 safe zones, and 44 years for 4 safe zones.

CONCLUSIONS

This study demonstrates the importance of achieving appropriate acetabular reorientation to enhance the longevity of the native hip following PAO. Although the LCEA and the Tönnis angle are the most common metrics used to assess appropriate acetabular correction, this study shows that adequately addressing retroversion and the ACEA has a greater impact on improving the natural history.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Three-dimensional hip joint congruity evaluation of the borderline dysplasia: Zonal-acetabular radius of curvature

In theory, a hemispherical acetabulum provides the ideal hip congruity in any hip position. However, it remains unknown how the three-dimensional acetabular morphology of borderline dysplastic and frank dysplastic hips compare to normal hips. This study inquires if borderline dysplastic zonal-acetabular curvatures in the anterior, superior, and posterior zones are different from normal or dysplastic hips three-dimensionally. One-hundred and fifteen hips, grouped as control (25°≤ LCEA <40°), 36 hips; borderline (20°≤ LCEA <25°), 32 hips; dysplasia (LCEA ≤20°), 47 hips were analyzed. The radii of acetabular curvature for the anterior, superior, and posterior zones were calculated as the zonal-acetabular radius of curvature (ZARC). The mean acetabular roof obliquity of the borderline (10.6 ± 4.3 [SD]°) was significantly larger than the control (3.0° ± 5.4°; P < .001) and smaller than the dysplasia (19.3° ± 5.7°; P < .001). Although the mean acetabular anteversion angle of the borderline (21.3° ± 3.7°) was significantly larger than control (17.9 ± 3.5°; P = .001), that of the borderline was not different from the dysplasia (23.3° ± 4.0°; P = .053). The mean anterior ZARC in the borderline (29.8 ± 2.6 mm) was significantly larger than the control (28.0 ± 2.2 mm; P = .011) and smaller than the dysplasia (31.5 ± 2.7 mm; P = .009). The mean superior ZARC in the borderline (25.7 ± 3.0 mm) was not different from the control (25.9 ± 2.2 mm; P = .934) or the dysplasia (25.8 ± 2.5 mm; P = .991). Although the mean posterior ZARC in the borderline (27.2 ± 2.5 mm) was not different from the control (26.4 ± 1.9 mm; P = .455), that of the borderline group was significantly smaller than the dysplasia (30.4 ± 3.3 mm; P < .001); that is, the severity of lateral under-coverage affects the anterior and/or posterior zonal-acetabular curvature.

Periacetabular osteotomy with or without arthroscopic management in patients with hip dysplasia: study protocol for a multicenter randomized controlled trial

Background

Hip dysplasia is one of the most common causes of hip arthritis. Its incidence is estimated to be between 3.6 and 12.8% (Canadian Institute for Health Information, Hip and knee replacements in Canada, 2017–2018: Canadian joint replacement registry annual report, 2019; Jacobsen and Sonne-Holm, Rheumatology 44:211–8, 2004). The Periacetabular Osteotomy (PAO) has been used successfully for over 30 years (Gosvig et al., J Bone Joint Surg Am 92:1162–9, 2010), but some patients continue to exhibit symptoms post-surgery (Wyles et al., Clin Orthop Relat Res 475:336–50, 2017). A hip arthroscopy, performed using a small camera, allows surgeons to address torn cartilage inside the hip joint. Although both procedures are considered standard of care treatment options, it is unknown whether the addition of hip arthroscopy improves patient outcomes compared to a PAO alone. To delay or prevent future joint replacement surgeries, joint preservation surgery is recommended for eligible patients. While previous studies found an added cost to perform hip arthroscopies, the cost-effectiveness to Canadian Health care system is not known.

Methods

Patients randomized to the experimental group will undergo central compartment hip arthroscopy prior to completion of the PAO. Patients randomized to the control group will undergo isolated PAO. Patient-reported quality of life will be the primary outcome used for comparison between the two treatment groups as measured by The International Hip Outcome Tool (iHOT-33) (Saberi Hosnijeh et al., Arthritis Rheum 69:86–93, 2017). Secondary outcomes will include the four-square step test and sit-to-stand (validated in patients with pre-arthritic hip pain) and hip-specific symptoms and impairment using the HOOS; global health assessment will be compared using the PROMIS Global 10 Score; health status will be assessed using the EQ-5D-5L and EQ VAS questionnaires (Ganz et al., Clin Orthop Relat Res 466:264–72, 2008) pre- and post-operatively. In addition, operative time, hospital length of stay, adverse events, and health services utilization will be collected. A sub-group of patients (26 in each group) will receive a T1rho MRI before and after surgery to study changes in cartilage quality over time. A cost-utility analysis will be performed to compare costs and quality-adjusted life years (QALYs) associated with the intervention.

Discussion

We hypothesize that (1) concomitant hip arthroscopy at the time of PAO to address central compartment pathology will result in clinically important improvements in patient-reported outcome measures (PROMs) versus PAO alone, that (2) additional costs associated with hip arthroscopy will be offset by greater clinical improvements in this group, and that (3) combined hip arthroscopy and PAO will prove to be a cost-effective procedure.

Trial registration

ClinicalTrials.gov NCT03481010. Registered on 6 March 2020. Protocol version: version 3.

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.

Surgical Treatment for FAI: Arthroscopic and Open Techniques for Osteoplasty

PURPOSE OF REVIEW

To review the relevant literature and techniques regarding arthroscopic and open treatment of femoroacetabular impingement (FAI). To discuss both the senior authors' preferred method of arthroscopic and open treatment of FAI.

RECENT FINDINGS

Routine treatment of FAI has moved away from open techniques and is more focused arthroscopic methods. Arthroscopic treatment of FAI has more recently focused on differing techniques of hip access and capsular management. Open techniques still have a role in FAI, but indications for open management are focused on cases with more severe pathology. While arthroscopic techniques have shown better outcomes in the short term and higher return to play, it is not without risk and is a procedure with a steep learning curve. In cases of complex joint pathology, such as FAI coupled with dysplasia or Legg-Calve-Perthes, arthroscopy may be not indicated and an open approach preferred. We outline various techniques for both arthroscopic and open treatment of FAI and their outcomes when possible.

Is MRI an adequate replacement for CT scans in the three-dimensional assessment of acetabular morphology?

BACKGROUND

Appropriate three-dimensional imaging of the hip joint is a substantial prerequisite for planning and performing surgical correction of deformities. Although surgeons still use computed tomography (CT), modern and fast acquisition techniques of volumetric imaging using magnetic resonance imaging (MRI) for pelvic measurements enable similar resolution.

PURPOSE

This study was designed to determine if already described measures of acetabular morphology are comparable in both techniques and if assessment can be performed with equal intra-observer and inter-observer reliability.

MATERIAL AND METHODS

Thirty-two hips (16 patients) were examined with a pelvic CT and a MRI with 3-T. Pelvic orientation was standardized by each observer in coronal, axial, and sagittal planes. Acetabular version as well as seven acetabular sector angles were measured by two observers twice with a minimum of four weeks between sessions.

RESULTS

Inter-rater reliability showed excellent results for intra- and inter-rater reliability for CT (0.977-0.999) and MRI (0.969-0.998) measuring acetabular version and sector angles. Evaluating the reliability of CT and MRI for each observer revealed excellent results (0.972-0.998). Evaluating the Bland-Altman plots for intra-observer reliability showed an equal distribution of angles, within acceptable 95% limits of agreement. The same results were observed for inter-observer reliability evaluating CT and MRI as well as inter-method reliability.

CONCLUSION

Modern MRI scans are equally applicable to assess the bony pelvis as CT scans. In addition, MRI would enable the examination of soft tissues such as chondrolabral structures and muscle in the same examination. Since hip-preserving surgery is mostly conducted in younger patients, the reduction of radiation exposure is a benefit.

Hip Dysplasia Compromises the Outcome of Femoroacetabular Impingement Surgery

BACKGROUND

The optimal treatment for patients with symptomatic hip dysplasia presenting with labral tear is unknown. Although femoroacetabular osteoplasty (FAO) has excellent outcome for most femoroacetabular impingement patients, the presence of concomitant hip dysplasia has been implicated as an adverse prognostic factor. This study evaluated the outcome of FAO in a group of dysplastic hips and compared the outcome to a cohort of patients without dysplasia.

METHODS

Seventy-three patients (38 males, 35 females) with hip dysplasia who underwent FAO between 2007 and 2015 were identified. The minimum 2-year clinical, functional (modified Harris Hip Score and Short-Form 36 Health Survey), and radiological outcome was compared with 550 patients without dysplasia who underwent FAO by the same surgeon. The preoperative and postoperative alpha angle, Tonnis grade, joint space, and presence of chondral lesion were determined and compared. Conversion to total hip arthroplasty or revision FAO was considered as treatment failure.

RESULTS

The mean age in the dysplasia cohort was 30.7 ± 11.8 years compared to 34.5 ± 11.2 in the nondysplastic group. The mean follow-up was 4.3 years for dysplasia cohort and 4.1 for the nondysplastic group. The mean modified Harris Hip Score and Short-Form 36 Health Survey6 was significantly lower in the dysplastic group at 75.1 and 74.3 compared to 83.4 and 85.6 for the comparison group. There was a higher percentage of failure at 28.8% among dysplasia patients compared to 2.5% in the nondysplastic group.

CONCLUSION

Although labral repair and FAO may be an option for patients with hip dysplasia, the outcome in this population appears to be less optimal compared to femoroacetabular impingement patients with no evidence of dysplasia. Labral repair and osteoplasty should be limited to those with mild and borderline dysplasia.

Outcomes of Hip Arthroscopy With Concomitant Periacetabular Osteotomy, Minimum 5-Year Follow-Up

PURPOSE

To report minimum 5-year follow-up results of concomitant hip arthroscopy followed by periacetabular osteotomy (PAO) to treat acetabular dysplasia and intra-articular pathology, such as femoroacetabular impingement syndrome and labral tears.

METHODS

Data were prospectively collected from October 2010 to December 2012. Patients were included in this study if they underwent concomitant hip arthroscopy and PAO and if they had preoperative scores documented for the following measures: modified Harris Hip Score (mHHS), Nonarthritic Hip Score (NAHS), Hip Outcome Score-Sports-Specific Subscale (HOS-SSS), and pain on a visual analog scale (VAS). Patients who underwent reverse PAO to address acetabular retroversion were excluded. Follow-up was considered complete with these outcomes collected after surgery, as well as the abbreviated International Hip Outcome Tool and patient satisfaction on a 0-10 scale. Significance was set at P = .05.

RESULTS

Sixteen patients were eligible, all of whom had complete follow-up at a minimum of 5 years after surgery. There were 13 female subjects. The average age of the patients was 23.5 ± 6.8 years (range, 12.3-35.3 years), and the average body mass index was 24.3 ± 5.6 (range, 14.8-34.2). The mean lateral center-edge angle increased from 14.2° to 31.8° (P < .0001), and the anterior center-edge angle increased from 11.9° to 28.6° (P < .0001). The Tönnis angle of acetabular inclination decreased from 19.3° to 2.6° (P < .0001). The alpha angle decreased from 55.7° to 41.0° (P < .0001). All preoperative radiographs were Tönnis ≤1, and there was no progression of arthritis in radiographs taken at the latest clinical visit. All patient-reported outcomes scores demonstrated significant improvement from preoperative baseline to the minimum 5-year follow-up scores (mHHS, P < .001; NAHS, P < .001; HOS-SSS, P = .001). The VAS score decreased from a preoperative mean of 5.8 to 3.1 at the latest follow-up (P = .007). No conversion to total hip arthroplasty was reported.

CONCLUSIONS

Concomitant hip arthroscopy and PAO appears to be a safe and effective procedure with favorable mid-term outcomes that are durable compared to the short-term.

LEVEL OF EVIDENCE

Level IV, case series.

The Utility of Hip Arthroscopy in the Setting of Acetabular Dysplasia: A Systematic Review

PURPOSE

To compare patient-reported outcomes, progression of osteoarthritis, and conversion to total hip replacement in a dysplastic population when hip arthroscopy was used as an isolated treatment or as an adjunct to pelvic reorientation osteotomy.

METHODS

An exhaustive search of the existing literature was conducted according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Three databases (PubMed, CINAHL [Cumulative Index to Nursing and Allied Health Literature], Embase) were searched for studies from January 1930 through January 2018 published in the English language concerning the use of hip arthroscopy with diagnostic and therapeutic intentions in individuals with acetabular dysplasia. We excluded studies that presented ambiguous data sets or in which clear identification of the strategy for arthroscopy was absent.

RESULTS

The selection criteria were defined, and 33 studies (1,368 hip arthroscopies) were included in the final analysis. Studies that met the inclusion criteria were classified within 5 different categories: (1) hip arthroscopy for screening, chondral mapping, and planning (9 studies, 729 hip arthroscopies); (2) isolated arthroscopic treatment (13 studies, 434 hip arthroscopies); (3) outcomes of hip arthroscopy after previous reorientation pelvic osteotomy for acetabular dysplasia (4 studies, 52 hip arthroscopies); (4) arthroscopy followed by unplanned hip-preservation surgery (3 studies, 48 hip arthroscopies); and (5) combined arthroscopy and periacetabular osteotomy (4 studies, 106 hip arthroscopies). A risk-of-bias analysis showed a moderate to high risk of bias (level 3 or 4) within and across the included studies.

CONCLUSIONS

Although hip arthroscopy can be used to accurately grade the severity of chondral injuries in the native hip and provide zone-specific geographic mapping that may aid in subsequent surgical planning, there is insufficient evidence to conclude that arthroscopic characterization alone has any bearing on the ultimate clinical outcomes after osseous structural correction. Isolated arthroscopic treatment is not recommended in the setting of moderate to severe dysplasia, given the inferior clinical outcomes and risk of iatrogenic instability reported for this group. However, there is limited evidence to suggest that the isolated use of hip arthroscopy may be considered in cases of borderline acetabular dysplasia when careful attention is paid to labral and capsular preservation. Limited evidence supports the conclusion that after prior reorientation pelvic osteotomy for acetabular dysplasia, hip arthroscopy leads to improved clinical and functional outcomes and should be considered in this setting. Furthermore, there is insufficient evidence to conclude that failed hip arthroscopy compromises or challenges the ultimate clinical outcomes in patients undergoing subsequent reorientation pelvic osteotomy. Last, there is insufficient evidence to conclude that the adjunctive use of hip arthroscopy with reorientation pelvic osteotomy produces superior clinical outcomes compared with pelvic osteotomy alone. In summary, arthroscopic techniques may provide a useful complement to the correction of acetabular dysplasia and should be thoughtfully considered on a case-by-case basis when designing a comprehensive treatment strategy in dysplastic populations.

LEVEL OF EVIDENCE

Level IV, systematic review of Level III and IV studies.

Unaddressed Cam Deformity Is Associated with Elevated Joint Contact Stress After Periacetabular Osteotomy

BACKGROUND

Femoral cam deformity is frequently present in patients with acetabular dysplasia. Computational modeling can be used to identify how this deformity affects joint mechanics. Our purpose was to identify the relationship between cam deformity and joint contact stress after periacetabular osteotomy (PAO). We hypothesized that cam deformity is associated with an increase in peak joint contact stress after PAO.

METHODS

This was a retrospective review of patients treated for hip dysplasia with PAO without femoral osteochondroplasty. Patient-specific hip models created from preoperative and postoperative computed tomography (CT) scans were evaluated using discrete element analysis to determine maximum joint contact stress after PAO. Twenty hips with a postoperative increase in maximum contact stress were compared with 20 that demonstrated decreased maximum contact stress. Hips were assessed for cam deformity on cross-sectional imaging. Radiographic measures of acetabular dysplasia before and after PAO were assessed and compared with the change in maximum contact stress after PAO.

RESULTS

There was a moderate relationship between the change in maximum contact stress and the α angle (r = 0.31; p = 0.04), and the average α angle in the hips with increased maximum contact stress was significantly different from that in the hips with decreased joint contact stress (51° ± 11.4° versus 42° ± 5.1°; p = 0.04). All 6 hips with an α angle of >60° demonstrated increased joint contact stress.

CONCLUSIONS

Cam deformity is common in patients with hip dysplasia. In our study, α angles of >60° were associated with increased postoperative joint contact stress. The α angle should be assessed preoperatively, and deformity should be addressed for optimal joint mechanics after PAO.

CLINICAL RELEVANCE

A reduction in joint contact stress is a proposed mechanism for the increased joint longevity following periacetabular osteotomy for hip dysplasia. Impingement from abnormal femoral offset negatively impacts clinical outcome, but this finding has not been evaluated from a biomechanical perspective previously and a threshold for performing femoral osteochondroplasty has not been established previously. This study provides biomechanical evidence supporting surgical management of femoral cam deformity for an α angle of >60°.

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

BACKGROUND

The definitive treatment of borderline-to-mild dysplasia remains controversial. A more comprehensive understanding of the etiology of osteoarthritis (OA) and clarification of any possible association between borderline-to-mild dysplasia and the pathogenesis of OA are essential.

QUESTIONS/PURPOSES

(1) Does the distribution of acetabular subchondral bone density increase according to dysplasia severity? (2) Is there an association between borderline-to-mild dysplasia and OA pathogenesis?

METHODS

We evaluated bilateral hips of patients with developmental dysplasia of the hip who underwent eccentric rotational acetabular osteotomy (ERAO) for inclusion in the dysplasia group and contralateral hips of patients with unilateral idiopathic osteonecrosis of the femoral head (ONFH) who underwent curved intertrochanteric varus osteotomy (CVO) for the control group. ERAO was performed in 46 patients and CVO was performed in 32 patients between January 2013 and August 2016 at our institution. All patients underwent bilateral hip CT. The study included 55 hips categorized according to dysplasia severity: (1) borderline-mild, 19 hips (15° ≤ lateral center-edge angle [LCEA] < 25°); (2) moderate, 20 hips (5° ≤ LCEA < 15°); (3) severe, 16 hips (LCEA < 5°); and (4) control, 15 hips. Thirty-seven dysplastic hips (age < 15 or > 50 years old, prior hip surgery, subluxation, aspherical femoral head, cam deformity, and radiographic OA) and 17 control hips (age < 15 or > 50 years old, bilateral ONFH, LCEA < 25° or ≥ 35°, cam deformity, and radiographic OA) were excluded. CT-osteoabsorptiometry (OAM) predicts physiologic biomechanical conditions in joints by evaluating subchondral bone density. We evaluated the distribution of subchondral bone densities in the acetabulum with CT-OAM, dividing the stress distribution map into six segments: anteromedial, anterolateral, centromedial, centrolateral, posteromedial, and posterolateral. We calculated the percentage of high-density area, which was defined as the upper 30% of Hounsfield units values in each region and compared least square means difference estimated by the random intercept model among the four groups.

RESULTS

In all regions, the percentage of high-density area did not differ between the borderline-mild group and the control (eg, anterolateral, 16.2 ± 5.6 [95% CI, 13.4 to 18.9] versus 15.5 ± 5.7 [95% CI, 12.4 to 18.5, p = 0.984]; centrolateral, 39.1 ± 5.7 [95% CI, 36.4 to 41.8] versus 39.5 ± 4.7 [95% CI, 36.6 to 42.5, p = 0.995]; posterolateral, 10.9 ± 5.2 [95% CI, 8.0 to 13.8] versus 15.1 ± 6.8 [95% CI, 11.7 to 18.5, p = 0.389]). In the anterolateral region, a smaller percentage of high-density area was observed in the borderline-mild group than in both the moderate group (16.2 ± 5.6 [95% CI, 13.4-18.9] versus 28.2 ± 5.1 [95% CI, 25.5-30.9], p < 0.001) and the severe group (16.2 ± 5.6 [95% CI, 13.4-18.9] versus 22.2 ± 6.8 [95% CI, 19.2-25.2, p = 0.026).

CONCLUSIONS

Our results suggest that the cumulative hip stress distribution in borderline-to-mild dysplasia was not concentrated on the lateral side of the acetabulum, unlike severe dysplasia.

CLINICAL RELEVANCE

Based on the stress distribution pattern, our results may suggest that there is no association between borderline-to-mild dysplasia and the pathogenesis of OA. Further studies are needed to evaluate the association between borderline-to-mild dysplasia and instability of the hip.

Modified Shelf Acetabuloplasty Endoscopic Procedure With Allograft for Developmental Hip Dysplasia Treatment

Hip dysplasia has been identified as one of the leading causes of osteoarthritis. However, hip arthroscopy alone, in the setting of hip dysplasia, remains controversial. In borderline hip dysplasia, with lateral center-edge angle (LCEA) between 18° and 25°, good outcomes have been reported with appropriate capsular and labral management. However, in severe hip dysplasia, with LCEA below 18°, there is an acetabular bony structural deficiency that must be addressed. Even with the potential benefit of hip arthroscopy in addressing intra-articular injuries related to the instability, it cannot be used for soft-tissue procedures. Periacetabular osteotomy remains the gold standard to address that matter; however, its invasive nature along with the long recovery time leaves some patients unwilling to undergo this procedure. New minimally invasive endoscopic procedures, derived from open techniques, describe acetabular autologous bone grafting as an alternative. Donor-side morbidity is always a concern when using autografts; we believe that the use of bone allograft will decrease this potential issue and make the procedure itself less invasive. This Technical Note will describe a type of endoscopic shelf acetabuloplasty using an allograft iliac bone graft.

Arthroscopy and arthrotomy to address intra-articular pathology during PAO for hip dysplasia demonstrates similar short-term outcomes

Periacetabular osteotomy (PAO) remains the gold standard procedure for joint preservation in symptomatic developmental dysplasia of the hip (DDH). Hip arthroscopy (HA) and open arthrotomy have been used to correct intra-articular pathology at the time of PAO, but there is limited data regarding differences in outcomes between these techniques when performed at the time of PAO. The aim of this study was to determine if short-term clinical outcomes differed between patients managed with HA versus arthrotomy to evaluate and treat intra-articular pathology at the time of PAO to discern if one technique is associated with better pain and functional results. Data were retrospectively reviewed from two surgeons at one institution managing DDH patients from September 2013 to December 2015. One surgeon treated patients with PAO and arthrotomy (N = 32), while the other performed PAO and HA (N = 39). There were 87% women, median age was 28 years and mean BMI was 25. Seventy-five percent of all patients received an intra-articular intervention. Patients completed 13 PROs at the pre-operative and 1-year post-operative clinical visits. Pre-operatively, there were no differences in any of the 13 PROs between patients treated with HA versus arthrotomy (P ≥ 0.076). Patients treated with PAO and arthrotomy experienced greater mean improvement in two out of the 13 PROs; the other 11 showed no differences. No treatment effect was observed for any of the 13 PROs using multivariable modelling that accounted for severity of dysplasia and degree of arthritis. Few differences were shown in short-term clinical outcomes between HA and arthrotomy at the time of PAO. This work highlights the need for a high quality randomized clinical trial to provide definitive guidance on whether hip preservation surgeons should address intra-articular pathology at the time of PAO for DDH and which technique best serves this purpose.

Prevalence and morphological features of acetabular dysplasia with coexisting femoroacetabular impingement-related findings in a Japanese population: a computed tomography-based cross-sectional study

The coexistence of acetabular dysplasia (AD) and femoroacetabular impingement (FAI) has not been well discussed. This study was performed to elucidate the prevalence and morphological features of AD with coexisting FAI-related findings in a Japanese population. Computed tomography images were retrospectively evaluated. AD was classified as definite or borderline. The morphological findings that defined cam deformity were an α angle of ≥55°, head–neck offset ratio (HNOR) of <0.13, pistol grip deformity positivity and herniation pit positivity. The morphological findings that defined pincer deformity were acetabular index of ≤0° and a retroverted acetabulum. In total, 128 hips (male, 64; female, 64) were analyzed. The prevalence of coexistence of AD and FAI-related findings was detected in 23.4% of hips (definite AD and FAI, 7.8%; borderline AD and FAI, 15.6%). The percentages of hips with AD containing cam or pincer deformities among all were 54.3% and 4.3%, respectively. The percentage of AD with coexisting cam and that of AD with coexisting combined deformities was significantly higher in men, respectively. On the other hand, the most major morphological feature of FAI detected in hips with AD was a HNOR of <0.13. The coexistence of AD and FAI-related findings was common in a Japanese population, and 65.2% of hips with AD had some FAI-related findings. In discussing and managing AD, we recommend paying attention to the coexistence with FAI-related findings, especially in men and in borderline AD. In such hips, the most notable parameter as a morphological feature of FAI is a reduced HNOR.

Innovations in Joint Preservation Procedures for the Dysplastic Hip "The Periacetabular Osteotomy"

The Bernese periacetabular osteotomy is an effective treatment for symptomatic developmental dysplasia in the prearthritic young adult hip. Refinements in the periacetabular osteotomy technique and perioperative management have markedly improved the clinical outcomes and recovery in these patients. We will review the clinical presentation of acetabular dysplasia, indications for surgery, perioperative management, and contemporary refinements in technique including refined acetabular reduction, adjunctive hip arthroscopy, femoral head-neck osteochondroplasty, femoral procedures, and rapid recovery protocols. In well-selected patients, this reconstructive osteotomy should be considered safe and effective in alleviating pain and improving hip function in patients with symptomatic acetabular dysplasia.