Hip Morphology on Post-Reduction MRI Predicts Residual Dysplasia 10 Years After Open or Closed Reduction.

BACKGROUND: There is limited evidence supporting the value of morphological parameters on post-reduction magnetic resonance imaging (MRI) to predict long-term residual acetabular dysplasia (RAD) after closed or open reduction for the treatment of developmental dysplasia of the hip (DDH). METHODS: We performed a retrospective study of 42 patients (47 hips) undergoing open or closed reduction with a minimum 10 years of follow-up; 39 (83%) of the hips were in female patients, and the median age at reduction was 6.3 months (interquartile range [IQR], 3.3 to 8.9 months). RAD was defined as additional surgery with an acetabular index >2 standard deviations above the age- and sex-specific population-based mean value or Severin classification grade of >2 at last follow-up. Acetabular version and depth-width ratio, coronal and axial femoroacetabular distance, cartilaginous and osseous acetabular indices, transverse ligament thickness, and the thickness of the medial and lateral (limbus) acetabular cartilage were measured on post-reduction MRI. RESULTS: At the time of final follow-up, 24 (51%) of the hips had no RAD; 23 (49%) reached a failure end point at a median of 11.4 years (IQR, 7.6 to 15.4 years). Most post-reduction MRI measurements, with the exception of the cartilaginous acetabular index, revealed a significant distinction between the group with RAD and the group with no RAD when mean values were compared. The coronal femoroacetabular distance (area under the receiver operating characteristic curve [AUC], 0.95; 95% confidence interval [CI], 0.90 to 1.00), with a 5-mm cutoff, and limbus thickness (AUC, 0.91; 95% CI, 0.83 to 0.99), with a 4-mm cutoff, had the highest discriminatory ability. A 5-mm cutoff for the coronal femoroacetabular distance produced 96% sensitivity (95% CI, 78% to 100%), 83% specificity (95% CI, 63% to 95%), 85% positive predictive value (95% CI, 65% to 96%), and 95% negative predictive value (95% CI, 76% to 100%). A 4-mm cutoff for limbus thickness had 96% sensitivity (95% CI, 78% to 100%), 63% specificity (95% CI, 41% to 81%), 71% positive predictive value (95% CI, 52% to 86%), and 94% negative predictive value (95% CI, 70% to 100%). CONCLUSIONS: Coronal femoroacetabular distance, a quantitative metric assessing a reduction's concentricity, and limbus thickness, a quantitative metric assessing the acetabulum's cartilaginous component, help to predict hips that will have RAD in the long term after closed or open reduction. LEVEL OF EVIDENCE: Diagnostic Level IV . See Instructions for Authors for a complete description of levels of evidence.

Treatment of Symptomatic Residual Deformity in Legg-Calvé-Perthes Disease: Mid-Term Outcomes and Predictors of Failure After Surgical Hip Dislocation with Femoral-Head Reshaping and Relative Neck Lengthening.

BACKGROUND: Treating patients with symptomatic hips after healed Legg-Calvé-Perthes disease (LCPD) is challenging, mainly because of the complexity of the deformity. We performed a retrospective study to evaluate clinical and radiographic outcomes, measure the survival rate, and identify predictors of failure following a surgical hip dislocation (SHD) with femoral-head reshaping and relative femoral-neck lengthening for the treatment of symptomatic residual hip deformity after healed LCPD. METHODS: We identified 60 patients undergoing SHD for the treatment of symptomatic residual LCPD deformity. Fifty-one (85%) of the patients (mean age, 16.3 ± 4.7 years; 21 male patients [41%]), were followed ≥4 years after surgery. We defined surgical failure as conversion to, or recommendation for, total hip arthroplasty (THA) or a Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain score of ≥10 at the most recent follow-up. We used a multivariable Cox proportional hazards model to identify factors that were predictive of failure. The rate of survival free from failure was estimated using a Kaplan-Meier curve. RESULTS: Twenty (39%) of the patients met 1 of the end-point criteria for surgical failure, while the hips of the remaining 31 (61%) of the patients were successfully preserved at a median follow-up of 10.2 years (interquartile range, 5.7 to 12.9 years). The estimated survival was 80% (95% confidence interval [CI] = 70% to 92%) at 5 years and 66% (95% CI = 53% to 81%) at 10 years. Independent factors associated with surgical failure were the severity of preoperative pain as assessed by the WOMAC pain score (hazard ratio [HR] = 1.16; 95% CI = 1.03 to 1.30; p = 0.01) and the severity of the deformity as assessed by the anteroposterior alpha angle (HR = 1.06; 95% CI = 1.01 to 1.11; p = 0.01). CONCLUSIONS: We found that SHD with relative femoral-neck lengthening and osteochondroplasty of the femoral head-neck junction was associated with improved deformity as assessed radiographically and decreased pain and symptoms of stiffness among patients with symptomatic residual LCPD deformity. Preoperative pain and deformity were identified as predictors of surgical failure. Further research is needed to establish the role of SHD and other procedures in preserving the hip over the long term. LEVEL OF EVIDENCE: Therapeutic L evel IV . See Instructions for Authors for a complete description of levels of evidence.

MRI hip morphology is abnormal in unilateral DDH and increased lateral limbus thickness is associated with residual DDH at minimum 10-year follow-up.

Purpose: The purpose of the study was to compare the post-reduction magnetic resonance imaging morphology for hips that developed residual acetabular dysplasia, hips without residual dysplasia, and uninvolved contralateral hips in patients with unilateral developmental dysplasia of the hip undergoing closed or open reduction and had a minimum 10-year follow-up. Methods: Retrospective study of patients with unilateral dysplasia of the hip who underwent open/closed hip reduction followed by post-reduction magnetic resonance imaging. Twenty-eight patients with a mean follow-up of 13 ± 3 years were included. In the treated hips, residual dysplasia was defined as subsequent surgery for residual acetabular dysplasia or for Severin grade > 2 at latest follow-up. On post-reduction, magnetic resonance imaging measurements were performed by two readers and compared between the hips with/without residual dysplasia and the contralateral uninvolved side. Magnetic resonance imaging measurements included acetabular version, coronal/ axial femoroacetabular distance, acetabular depth-width ratio, osseous/cartilaginous acetabular indices, and medial/lateral (limbus) cartilage thickness. Results: Fifteen (54%) and 13 (46%) hips were allocated to the "no residual dysplasia" group and to the "residual dysplasia" group, respectively. All eight magnetic resonance imaging parameters differed between hips with residual dysplasia and contralateral uninvolved hips (all p < 0.05). Six of eight parameters differed (all p < 0.05) between hips with and without residual dysplasia. Among these, increased limbus thickness had the largest effect (odds ratio = 12.5; p < 0.001) for increased likelihood of residual dysplasia. Conclusions: We identified acetabular morphology and reduction quality parameters that can be reliably measured on the post-reduction magnetic resonance imaging to facilitate the differentiation between hips that develop with/without residual acetabular dysplasia at 10 years postoperatively. Level of evidence: level III, prognostic case-control study.

The incidence and risk factors for stress fracture following periacetabular osteotomy.

AIMS: The aims of this study were to characterize the incidence and risk factors associated with stress fractures following periacetabular osteotomy, and to determine their effect on osteotomy union. METHODS: We retrospectively reviewed all periacetabular osteotomies (PAOs) performed for developmental dysplasia of the hip (DDH) at one institution over a six-year period between 2012 and 2017. Perioperative factors were recorded, and included demographic and surgical data. Postoperatively, patients were followed for a minimum of one year with anteroposterior and false profile radiographs of the pelvis to monitor for evidence of stress fracture and union of osteotomies. We characterized the incidence and locations of stress fractures, and used univariate and multivariable analysis to identify factors predictive of stress fracture and the association of stress fracture on osteotomy union. RESULTS: A total of 331 patients underwent PAO during the study period with 56 (15.4%) stress fractures: 46 fractures of the retroacetabular posterior column, five cases of ischiopubic stress fracture, and five cases of concurrent ischiopubic and retroacetabular stress fractures. Overall, 86% (48/56) healed without intervention. Univariate analysis revealed that stress fractures occurred more frequently in females (p = 0.040), older patients (mean age 27.6 years (SD 8.4) vs 23.8 (SD 9.0); p = 0.003), and most often with the use of the broad Mast chisel (28.5%; p < 0.001). Multivariable analysis revealed that increasing age (odds ratio (OR) 1.04; 95% CI 1.01 to 1.07; p = 0.028) and use of the broad Mast chisel (OR 5.1 (95% CI 1.3 to 19.0) compared to narrow Ganz chisel; p = 0.038) and surgeon (p = 0.043) were associated with increased risk of stress fracture. Patients with stress fractures were less likely to have healed osteotomies after one-year follow-up (76% vs 96%; p < 0.001). CONCLUSION: Stress fracture of the posterior column may be an under-recognized complication following PAO, and the rate may be influenced by surgical technique. Consideration should be given to using a narrow chisel during the ischial cut to reduce the risk of stress propagation through the posterior column.Cite this article: Bone Joint J 2022;104-B(9):1017-1024.