Radiographically successful periacetabular osteotomy does not achieve optimal contact mechanics in dysplastic hips

BACKGROUND

Optimal correction of hip dysplasia via periacetabular osteotomy may reduce osteoarthritis development by reducing damaging contact stress. The objective of this study was to computationally determine if patient-specific acetabular corrections that optimize contact mechanics can improve upon contact mechanics resulting from clinically successful, surgically achieved corrections.

METHODS

Preoperative and postoperative hip models were retrospectively created from CT scans of 20 dysplasia patients treated with periacetabular osteotomy. A digitally extracted acetabular fragment was computationally rotated in 2-degree increments around anteroposterior and oblique axes to simulate candidate acetabular reorientations. From discrete element analysis of each patient's set of candidate reorientation models, a mechanically optimal reorientation that minimized chronic contact stress exposure and a clinically optimal reorientation that balanced improving mechanics with surgically acceptable acetabular coverage angles was selected. Radiographic coverage, contact area, peak/mean contact stress, and peak/mean chronic exposure were compared between mechanically optimal, clinically optimal, and surgically achieved orientations.

FINDINGS

Compared to actual surgical corrections, computationally derived mechanically/clinically optimal reorientations had a median[IQR] 13[4-16]/8[3-12] degrees and 16[6-26]/10[3-16] degrees more lateral and anterior coverage, respectively. Mechanically/clinically optimal reorientations had 212[143-353]/217[111-280] mm2 more contact area and 8.2[5.8-11.1]/6.4[4.5-9.3] MPa lower peak contact stresses than surgical corrections. Chronic metrics demonstrated similar findings (p ≤ 0.003 for all comparisons).

INTERPRETATION

Computationally selected orientations achieved a greater mechanical improvement than surgically achieved corrections; however, many predicted corrections would be considered acetabular over-coverage. Identifying patient-specific corrections that balance optimizing mechanics with clinical constraints will be necessary to reduce the risk of osteoarthritis progression after periacetabular osteotomy.

Comparing Propofol With Fentanyl and Midazolam for Sedation in Closed Reductions of Traumatic Hip Dislocations

Traumatic native hip dislocations require prompt reduction of the dislocation to limit the risk of avascular necrosis and resultant hip arthrosis. Although closed reduction under sedation is frequently attempted, there is minimal evidence about which sedative agent is most safe and effective. The goal of this study was to compare the efficacy of propofol vs combination fentanyl/midazolam for closed reduction under sedation of traumatic native hip dislocations. This was a single-center retrospective review. The main outcome measures were the rate of successful closed reduction with propofol vs combination fentanyl/midazolam and time from the start of sedation to radiographic evidence of reduction. Fifty-four patients with traumatic native hip dislocations were identified. Closed reduction under sedation with propofol was successful in 11 of 14 attempts compared with 4 of 11 attempts with combination fentanyl/midazolam (P=.04). The fentanyl/midazolam group had 6.4 times the odds (95% CI, 1.1-37.7) of failed closed reduction compared with the propofol group. The median time to reduction in the propofol group was 14 minutes vs 45 minutes for the fentanyl/midazolam group (P=.18). Patients who had failed closed reduction with fentanyl/midazolam had a median time to reduction of 100 minutes. There was no difference in sedation-related complications between the 2 groups. We therefore conclude that sedation with propofol is significantly more effective than combination fentanyl/midazolam for closed reduction of native hip dislocations. To minimize unsuccessful reduction attempts and shorten total time to reduction, we recommend against the use of combination fentanyl/midazolam because of the high risk of failure. [Orthopedics. 2023;46(2):86-92.].

Joint contact stress improves in dysplastic hips after periacetabular osteotomy but remains higher than in normal hips

AIM

The purpose of this study was to use computational modeling to determine if surgical correction of hip dysplasia restores hip contact mechanics to those of asymptomatic, radiographically normal hips.

METHODS

Discrete element analysis (DEA) was used to compute joint contact stresses during the stance phase of normal walking gait for 10 individuals with radiographically normal, asymptomatic hips and 10 age- and weight-matched patients with acetabular dysplasia who underwent periacetabular osteotomy (PAO).

RESULTS

Mean and peak contact stresses were higher (p < 0.001 and p = 0.036, respectively) in the dysplastic hips than in the matched normal hips. PAO normalised standard radiographic measurements and medialised the location of computed contact stress within the joint. Mean contact stress computed in dysplastic hips throughout the stance phase of gait (median 5.5 MPa, [IQR 3.9-6.1 MPa]) did not significantly decrease after PAO (3.7 MPa, [IQR 3.2-4.8]; p = 0.109) and remained significantly (p < 0.001) elevated compared to radiographically normal hips (2.4 MPa, [IQR 2.2-2.8 MPa]). Peak contact stress demonstrated a similar trend. Joint contact area during the stance phase of gait in the dysplastic hips increased significantly (p = 0.036) after PAO from 395 mm2 (IQR 378-496 mm2) to 595 mm2 (IQR 474-660 mm2), but remained significantly smaller (p = 0.001) than that for radiographically normal hips (median 1120 mm2, IQR 853-1444 mm2).

CONCLUSIONS

While contact mechanics in dysplastic hips more closely resembled those of normal hips after PAO, the elevated contact stresses and smaller contact areas remaining after PAO indicate ongoing mechanical abnormalities should be expected even after radiographically successful surgical correction.

The International Hip Dysplasia Institute (IHDI) classification is more informative than the Tönnis classification

BACKGROUND

A new, supposedly more reproducible radiographic classification, set to replace the Tönnis classification of hip dislocations, was proposed in 2015: the International Hip Dysplasia Institute (IHDI) classification.

PURPOSE

To compare the IHDI classification with the Tönnis classification when evaluating the severity of hip dislocations as well as their respective inter- and intra-observer reliability.

MATERIAL AND METHODS

Since January 2000, Swedish-born children with a hip dislocation were prospectively registered. From this registry, radiographs of 97 hips in 79 patients (91% girls; median age = 7 months), born in 2000-2009, were analyzed. Two observers, one consultant and one resident, classified each hip both by IHDI and Tönnis twice.

RESULTS

The IHDI classification had a more even distribution of grades with the majority in grade 2-3. The Tönnis classification graded the majority (77%) of the patients as grade 2 and equally among the other grades. There was moderate inter-observer agreement using both methods calculated with Kappa, 0.61 (95% confidence interval [CI] = 0.44-0.79) for Tönnis and 0.62 (95% CI = 0.49-0.74) for IHDI. The resident calculated Tönnis with weak intra-observer reliability of 0.57 (95% CI = 0.40-0.74) compared to high intra-observer reliability of 0.86 (95% CI = 0.74-0.98) for the consultant. Both observers graded IHDI with high intra-observer reliability.

CONCLUSION

IHDI is more discriminative than the Tönnis classification when evaluating the severity of a hip dislocation in infants.

Posterior acetabular wall morphology is an independent risk factor that affects the occurrence of acetabular wall fracture in patients with traumatic, posterior hip dislocation

PURPOSE

Smaller posterior acetabular walls have been shown to independently influence the risk for bipolar hip dislocation. We asked whether differences would also be observed in patients with traumatic posterior hip dislocation with and without posterior wall fractures.

METHODS

Between 2012 and 2020 we observed 67 traumatic posterior hip dislocations. Of these, 43 traumatic posterior hip dislocations in 41 patients met the inclusion criteria. Eighteen dislocations were excluded with an acetabular fracture other than posterior wall fracture and six dislocations had insufficient computed tomography (CT) data. The mean age was 41 ± 11 years, 32 males and nine females. We observed 26 traumatic hip dislocations with posterior wall fractures and 17 without. All patients underwent polytrauma CT scans and postoperative/postinterventional pelvic CT scans. On axial CT-scans, posterior wall determining angles were measured.

RESULTS

Patients with posterior wall fractures were not significantly older than patients without posterior wall fractures (42 ± 12 vs. 38 ± 10 years; p = 0.17). Patients without posterior wall fractures had significantly smaller posterior acetabular sector angles (84° ± 10°) than did patients with posterior wall fractures (105° ± 12°) (p < 0.01; OR 1.178). Likewise, the posterior wall angle was significantly smaller in patients without posterior wall fracture (62° ± 9°) than in those with posterior wall fractures (71° ± 8°) (p < 0.01; OR 1.141).

CONCLUSION

Both posterior acetabular sector angle and posterior wall angle are independent factors determining the posterior wall fracture morphology in patients with traumatic posterior hip dislocation. Age and the observed trauma mechanism did not differentiate between traumatic posterior hip dislocations with and without posterior wall fractures.

The anterior hip capsule is thinner in dysplastic hips: a study comparing different young adult hip patients

PURPOSE

To investigate the thickness and intra-substance change of anterior capsule of the hip joint, and compare the difference of the capsular features in patients with different statuses of hip stability.

METHODS

A retrospective study was performed to review a hip preservation database. Using the lateral center edge angle(LCEA), patients with borderline dysplasia of the hip (BDH) of 20° ≤ LCEA ≤ 25°, femoracetabular impingement(FAI) with LCEA > 30° and dysplasia of the hip (DH) of LCEA < 20° were enrolled and stratified into different treatment groups. The patients' imaging was reviewed by two experienced musculoskeletal radiologists who were blinded to clinical outcomes. Thickness and intra-substance change of the anterior hip capsule was measured on the sagittal oblique sequences of MRI. A surgeon measured the thickness of the anterior hip capsule during arthroscopy. The capsular thickness and intra-substance change were compared among different groups.

RESULTS

Thirty patients (17 women and 13 men) enrolled in each group (FAI, BDH, and DH) matched by sex and ages were evaluated. There were no significant differences in terms of age, sex, BMI, Alpha angle, and Tönnis grade among all three groups. The mean thickness of the anterior capsule in the DH group was 3.2 ± 0.5 mm, which was significantly thinner than that in the BDH and FAI groups (4.5 ± 0.8 mm and 4.7 ± 0.6 mm), and there was no significant difference in capsular thickness between the BDH and FAI groups. The Median of anterior capsule thickness via arthroscopic measuring was 6 mm and 7 mm in the BDH and FAI groups respectively, which has no statistical difference. The intra-substance change of the anterior capsule shows a significant difference among the three groups, and a higher incidence of delamination of the capsule was found in DH groups (p < 0.001).

CONCLUSIONS

Patients with hip dysplasia have a significantly reduced capsular thickness on MRI and delaminated anterior joint capsule, which could be a sequence of instability. The clinical relevance of this study is that capsular thickness and intra-substance changes of the anterior capsule vary which could alter capsular management strategies.

LEVEL OF EVIDENCE

Level III of evidence, DIAGNOSTIC STUDIES, No consistently applied reference standard.

A retrospective study of hip posterior fracture-dislocation: closed reduction at the emergency department or in the operation theater?

BACKGROUND

For hip posterior fracture-dislocation, the current consensus is to perform joint reduction within 6 h to prevent sequelae. However, whether a closed reduction (CR) should be performed at the emergency department (ED) or in the operation theater (OT) remains debatable. We aimed to assess the incidence and factors predictive of CR failure at the ED in patients with hip posterior fracture-dislocation.

METHODS

Patients with hip posterior fracture-dislocation between 2009 and 2019 were included. Age, sex, body mass index (BMI), injury severity score, new injury severity score, time from injury to first reduction attempt (TIR), presence of associated femoral head fracture, posterior wall marginal impaction, and posterior wall fragment size were compared between patients with CR success and patients with CR failure at the ED.

RESULTS

Fifty-five patients with hip posterior fracture-dislocation experienced CR attempts at the ED and were enrolled in the study. Thirty-eight (69.1%) hips were reduced successfully at the ED, and 17 (30.9%) experienced failure. No significant differences in age, sex, BMI, presence of femoral head fracture, marginal impaction, or size of the posterior wall fragment were found between the groups. TIR was significantly shorter in the successful CR group (2.24 vs. 4.11 h, p = 0.01). According to receiver operating characteristic curve analysis, 3.5 h was the cut-off time.

CONCLUSIONS

For patients with hip posterior fracture-dislocation, TIR was a critical factor for successful CR. If the time interval exceeds 3.5 h from injury, the success rate of bedside CR at the ER is likely to decrease, and the OT should be prepared in case of failed bedside CR.

LEVEL OF EVIDENCE III

Radiologic restoration inaccuracy increases postoperative dislocation in primary total hip arthroplasty: a retrospective study with propensity score matching

BACKGROUND

Dislocation is a complicated process and associated with multivariate etiology and risk factors. The purpose of this study was to verify if radiologic restoration inaccuracy increases postoperative dislocation in primary total hip arthroplasty (THA) individually or synergistically.

METHODS

From 2017 to 2020, we identified 76 (1.9%) patients who suffered postoperative dislocations from 3926 THAs in our institution. After excluded patients with previously proven patient-related and implant-related risk factors, the remaining patients were used to match a 1:1 control patients who were without dislocation. The cup position (inclination and anteversion angles), hip offset (HO), leg length discrepancy (LLD), and abductor lever arm (ALA) were analyzed by univariate analyses and multivariate logistic regressions.

RESULTS

Measurements on radiographs showed excellent interobserver agreement (intraclass correlation coefficient (ICC) 0.922-0.952) and intraobserver agreements (ICC 0.933-0.967). HO restoration inaccuracy (without ± 5 mm) was associated with higher dislocation risk (OR 4.241 95% CI 1.440-12.492, P = 0.009). The restoration inaccuracy of the cup position, LLD, or ALA could not increase the dislocation risk individually. When combining the radiologic restoration inaccuracy factors, the HO + LLD restoration inaccuracy and HO + ALA restoration inaccuracy increased the odds of postoperative dislocation (OR 12.056, 95% CI 1.409-103.127, P = 0.023; OR 4.770, 95% CI 1.336-17.028, P = 0.016, respectively). Combining the four risk factors of cup safe zone, HO, LLD, and ALA, patients with 3 or 4 radiologic restoration inaccuracy factors showed a higher risk of dislocation (OR 13.500, 95% CI 1.340-135.983, P = 0.027).

CONCLUSION

Hip offset (HO) restoration inaccuracy increased the risk of dislocation following primary THA. Multivariate radiologic restoration accuracy is critical for the prevention of dislocation and needs to be valued by surgeons.

Femurkopfreduktionsosteotomie zur Verbesserung des femoroazetabulären Containments bei Morbus Perthes

Operationsziel

Wiederherstellung der Hüftkongruenz und des Containments durch zentrale Hüftkopfresektion/Reduktion über eine erweiterte chirurgische Hüftluxation unter Erhaltung/Respektierung der Hüftkopfdurchblutung. Eine gleichzeitige oder spätere Reorientierung des Acetabulums durch Triple-Osteotomie oder PAO bei instabiler Hüfte kann in speziellen Fällen notwendig werden.

Indikationen

Die Indikation zur chirurgischen Hüftkopfreduktion ist praktisch unabhängig vom Alter bei jeglicher inkongruenten, asphärischen Hüftkopfsituation mit „hinged abduction“ (zu erwartende Endsituation wie Stulberg IV und V) gegeben. Dies kann noch bei aktivem wie auch bei bereits ausgeheiltem Morbus Perthes der Fall sein. Zudem kann bei einer Stulberg-V-Situation selbst im adulten Alter noch eine Verbesserung erziel werden. Nach Resektion muss noch ein tragfähiger Resthüftkopf vorhanden bleiben, d. h. mindestens noch 50 % des ausgeweiteten Hüftkopfes. Die dafür beste Planung erfolgt in der „vergleichenden“ 3‑D-Rekonstruktion.

Kontraindikationen

Völlig zerstörter Knorpel oder Hüftkopf.

Operationstechnik

Identisches Operationsvorgehen wie für die klassische chirurgische Hüftluxation. Präparation der retinakulären Flaps. Unter Respektierung und in Kenntnis der Gefäßversorgung Spaltung des Hüftkopfes gemäß dem zu entfernenden, nekrotischen Kopfanteil. Bildung eines möglichst sphärischen Hüftkopfes und Verschraubung der beiden Kopfanteile auf Schenkelhalsniveau. Distalisation und Fixierung des großen Trochanters. Je nach Kongruenz und Stabilität des Hüftkopfs in der Hüftpfanne kann eine primäre oder sekundäre Triple-OT oder PAO notwendig werden.

Weiterbehandlung

Die intraoperative Stabilität des Femurkopfes im Acetabulum muss erzielt worden sein, um eine beckengipsfreie, funktionelle Nachbehandlung zu gewährleisten: Stockentlastung mit Bodenkontakt ist erlaubt; keine aktive Rotation; Flexion aktiv und passiv bis 90 Grad ist erlaubt; vorerst keine spezifische Physiotherapie; je nach Heilungsverlauf sind diese Maßnahmen 8 bis 10 Wochen einzuhalten.

Ergebnisse

Gemäß unseren publizierten Nachuntersuchungen (aktuell 21 Jahre) sehen wir bei technisch korrekt durchgeführter Operation und korrekter Indikation sowie adäquater Nachbehandlung durchwegs gute Ergebnisse. Nekrosen des reduzierten Hüftkopfs haben wir nie beobachtet. Alle gespaltenen Hüftköpfe, respektive Schenkelhälse sind primär geheilt.

What Factors Are Associated With Postoperative Ischiofemoral Impingement After Bernese Periacetabular Osteotomy in Developmental Dysplasia of the Hip?

BACKGROUND

Any abnormal structures that contribute to the narrowing of the ischiofemoral space could induce ischiofemoral impingement. Bernese periacetabular osteotomy (PAO) medializes the hip center and, therefore, decreases contact stress on the cartilage in developmental dysplasia of the hip (DDH). However, medialization of the hip center might also narrow the ischiofemoral space, which may increase the risk of postoperative ischiofemoral impingement in patients with acetabular dysplasia who are undergoing PAO. Furthermore, the dysplastic hip has less ischiofemoral space and less space for the quadratus femoris. A few studies have focused on the amount of medialization of the hip center, but the proportion of postoperative ischiofemoral impingement after PAO has not been investigated.

QUESTIONS/PURPOSES

(1) What proportion of patients develop ischiofemoral impingement after undergoing unilateral PAO for DDH? (2) What radiographic factors are associated with postoperative ischiofemoral impingement in patients who underwent PAO for DDH? (3) How much hip center medialization is safe so as to avoid postoperative ischiofemoral impingement during PAO?

METHODS

Between 2014 and 2016, we treated 265 adult patients who had symptomatic residual acetabular dysplasia (lateral center-edge angle less than 20°) using PAO. During that time, we generally offered PAO to patients with acetabular dysplasia when the patients had no advanced osteoarthritis (Tönnis grade < 2). Of those, we considered only patients who underwent primary PAO without femoral osteotomy as potentially eligible. Based on that, 65% (173 of 265) were eligible; a further 9% (24 of 265) were excluded due to leg length discrepancy, spine disorders, or joint replacement in the contralateral side, and another 6% (17 of 265) of patients were lost before the minimum study follow-up of 2 years or had incomplete datasets, leaving 50% (132 of 265) for analysis in this retrospective study at a mean of 2.70 ± 0.71 years. The diagnosis of ischiofemoral impingement was defined by symptoms, MRI, and diagnostic ischiofemoral injection. We ascertained the percentage of patients with this diagnosis to answer the first research question. To answer the second question, we divided the patients into two groups: PAO patients with ischiofemoral impingement and PAO patients without ischiofemoral impingement. The demographic data and preoperative imaging parameters of patients in both groups were compared. There were statistical differences in acetabular version, ischial angle, neck-shaft angle, the presence of positive coxa profunda sign, McKibbin index, ischiofemoral space, quadratus femoris space, anterior acetabular section angle, and the net amount of hip center medialization. To investigate potential factors associated with postoperative ischiofemoral impingement in patients who underwent PAO, these factors underwent binary logistic regression analysis. To answer the third question, the cutoff value of the net amount of hip center medialization was evaluated using receiver operator characteristic curve and the Youden index method.

RESULTS

We found that 26% (35 of 132) of PAO dysplastic hips had postoperative ischiofemoral impingement. After controlling for confounding variables such as acetabular version, ischial angle, femoral neck version, McKibbin index, and ischiofemoral space, we found that an increasing neck-shaft angle (odds ratio 1.14 [95% confidence interval 1.01 to 1.29]; p = 0.03), a positive coxa profunda sign (OR 0.13 [95% CI 0.03 to 0.58]; p < 0.01), and an increasing net amount of hip center medialization (OR 2.76 [95% CI 1.70 to 4.47]; p < 0.01) were associated with postoperative ischiofemoral impingement in patients with DDH who underwent PAO (R 2 = 0.73). The cutoff values of neck-shaft angle was 138.4°. The cutoff values of the net amount of hip center medialization was 1.9 mm.

CONCLUSIONS

Postoperative ischiofemoral impingement could occur in patients with acetabular dysplasia who have undergone PAO after hip center medialization. An increasing neck-shaft angle, a positive coxa profunda sign on preoperative imaging, and excessive medialization of the hip center are factors associated with ischiofemoral impingement development in these patients. Therefore, we suggest that physicians measure the ischiofemoral space on a preoperative CT when patients with DDH have an increasing neck-shaft angle (> 138.4°) or a positive coxa profunda sign on radiological imaging. During PAO, the amount of hip center medialization should be carefully controlled to keep these patients from developing postoperative ischiofemoral impingement.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Assessment of the endoprosthesis offset in a dysplastic coxarthrosis

Incorrectly developed acetabulum and subluxated hip joint may cause many problems for proper implantation of endoprosthesis. The aim of this work is to assess the radiological results of offset restoration and selection of endoprosthesis implant in a dysplastic hip joint. The study group consisted of patients who had a surgery in the period between 2016 and 2018. All of them had a cementless total hip endoprosthesis. The group consisted of 91 patients (96 hip joints), with an average age of 42 years (31-47 years). 55 left and 41 right hip joints. 70 females and 21 males. The control group consisted of patients who were not diagnosed with hip joint dysplasia. The control group consisted of 70 patients (70 hip joints), with an average age of 35 years (19-55 years). 53 females and 17 males. The radiographic assessment included the measuring of medialization and distalization which describe the offset of hip joint. The joint decentration was classified according to Crowe. Based on radiographic measurements we have achieved statistically significant (p<0.05) changes in medialization and distalization parameters. We have not noticed a statistically significant difference for medialization parameter (p=0.8259) after a surgery when compared to the control group. For all patients we have achieved a restoration of correct offset in the horizontal plane. The main idea behind endoprosthesis in a dysplastic coxarthosis is the implantation of endoprosthesis cup in an anatomically correct location. Small screw- in cup and conical stem offer great possibility of restoring correct offset of a dysplastic hip joint.

Cerebral Palsy: Hip Surveillance

Patients with cerebral palsy are known to be at risk for hip displacement and dislocation. Progressive hip displacement is known to cause a variety of problems including pain, impaired sitting balance, difficulty with perineal care, and decreased quality of life. To avoid these problems, hip reconstruction may be recommended and has been shown to lead to significant improvements in pain and health-related quality of life. To properly identify patients in need of intervention for hip displacement, hip surveillance is an active program consisting of clinical and radiographic monitoring in patients with cerebral palsy that allows for early detection of hip displacement in those at risk. As such, all children with cerebral palsy should be referred for hip surveillance at age 2 years. A growing body of literature has shown that hip surveillance along with appropriate orthopedic management decreases or prevents the incidence of hip dislocations, with direct implications on overall quality of life, in children with cerebral palsy. [Pediatr Ann. 2022;51(9):e353-e356.].

Pelvic radiography as a non-invasive screening tool for hiatal hernia in children with cerebral palsy

The diagnosis of hiatal hernia (HH), causing severe gastroesophageal reflux disease and complications in children with cerebral palsy (CP) is cumbersome because invasive investigations are required for diagnosis. Hip displacement, one of the most common complications in children with CP, can be diagnosed with a simple pelvic radiograph. This study aimed to evaluate the association between the severity of hip displacement and HH and the diagnostic accuracy of Reimers' hip migration percentage (MP) on pelvic radiography in assessing the presence of HH. A total of 52 children with CP (27 boys, 25 girls; mean age, 6.3 years; range, 0.6-17.4 years) who underwent esophagogastroduodenoscopy, upper gastrointestinal series and pelvic radiography between March 2013 and February 2020 were recruited. Demographic and clinical characteristics, as well as endoscopic and radiological findings, were evaluated and statistically analyzed. HH was defined as ≥ 2 cm proximal displacement of the gastroesophageal junction identified in esophagogastroduodenoscopy or upper gastrointestinal series, and MP was calculated by evaluating the pelvic radiograph. Of the 52 children enrolled in this study, HH was diagnosed in 18 children (34.6%). When the patients were classified and analyzed according to the MP result, HH was observed in 10%, 26.7%, and 70.6% in MP <33%, MP 33%-39%, and MP > 40% groups, respectively (P < .001). The optimal MP cutoff of 36.5% distinguished pediatric CP patients with HH from those without HH with a sensitivity of 78%, specificity of 68%, a positive predictive value of 56.0%, and a negative predictive value of 85.2%, respectively. The application of MP and the severity of hip displacement, which can be easily measured by simple radiography, may be useful and reliable in screening for detecting HH in children with CP. Retrospectively registered. This study was approved by the Institutional Review Board of Seoul National University Bundang Hospital (IRB No. B-2007-627-106).

A Review of Radiology Reports From Hip Surveillance Radiographs for Children With Cerebral Palsy

BACKGROUND

Measurement of migration percentage (MP) is fundamental to successful hip surveillance for children with cerebral palsy (CP). In British Columbia, Canada, children enrolled in the province's hip surveillance program get radiographs at the province's tertiary care pediatric hospital or their local community hospital. This study aimed to review the radiology reporting of images completed as part of hip surveillance.

METHODS

Pelvis radiographs completed between September 2015 and December 2019 of 960 children enrolled in the province's hip surveillance program were included. MP values measured by the program coordinator and corresponding value measured by the facility's radiologist, when present, were retrieved. Agreement in MP between the program coordinator and the radiologist was measured using Bland-Altman plots and intraclass correlation coefficients. Radiology reports for images completed at community facilities that prompted a referral to a pediatric orthopaedic surgeon, when reviewed by the hip surveillance team, were further reviewed for qualitative comments.

RESULTS

In total, 1849 radiographs were reviewed with 69.3% (1282) completed at the pediatric hospital and 30.7% (567) at 64 different hospitals or clinics. MP was reported for 20.6% (264/1282) of radiographs completed at the pediatric hospital and 3.0% (17/567) of the radiographs completed at community hospitals. Bland-Altman plot analyses found a MP mean difference of 1.2% (95% confidence interval=0.6%-1.8%) between the program coordinator and all radiologist reports with an intraclass correlation coefficient of 0.88 (95% confidence interval=0.86-0.90). There were 47 radiographs completed at community hospitals that resulted in a referral to a pediatric orthopaedic surgeon after review by the hip surveillance team. Eleven of these reports stated normal or unremarkable findings.

CONCLUSIONS

Radiologic reporting of images completed for hip surveillance for children with CP was inadequate to allow for the detection of hip displacement. Reporting of MP was rare, particularly in community hospitals. If radiology reporting will be utilized for hip surveillance in children with CP, education of radiologists is required.

Periacetabular vascular anatomy in high-riding dysplastic hips: a CT angiographic study

BACKGROUND

Developmental hip dysplasia (DDH) is shown to have osseous and neural abnormalities but literature is sparse with investigation of vascular structures. Therefore, we aimed to evaluate periacetabular vascular structures.

METHODS

By computerised tomography angiography (CTA), 13 highly dislocated hips of 11 patients' iliac bone to external iliac and obturatory artery and vein proximities were measured and compared with the same measurements of 20 healthy hips of 12 patients. Numbering from superior to inferior, a total of 7 axial images were created on the 2D CTA coronal images with 1 cm apart, the 4th being at the level of acetabular dome.

RESULTS

The mean age of the patients was 53 (18-72) years. Dysplastic hips tended to have curved (53%) and healthy hips tended to have straight iliac arteries (p = 0.037). As compared to healthy hips, external iliac veins were significantly closer to the bone at all levels, but the external iliac arteries were closest at 1st to 4th levels (p < 0.001) in dysplastic hips. The course of the obturatory arteries was similar in both groups (p = 0.147).

CONCLUSIONS

The external iliac artery and vein is in close proximity to the iliac bone which dangers acetabular screw, acetabular reaming or retractor placement in highly dislocated hips. The surgeon should be aware of this proximity in operations of these hips to avoid vascular complications.

Proximal Femoral Screw Hemiepiphysiodesis in Children With Cerebral Palsy Improves the Radiographic Measures of Hip Subluxation

BACKGROUND

Proximal femoral screw hemiepiphysiodesis (PFSH) is a promising technique for treatment of hip subluxation in children with cerebral palsy (CP). The aim of this study is to report radiographic outcomes of PFSH and to evaluate its role in changing the natural history of hip displacement in children with CP.

METHODS

This is a single center retrospective chart review of children with CP that underwent PFSH with at least 2 years of radiographic follow-up. Demographic information, surgical details, complications, additional surgical procedures, and need for screw exchange were recorded. Radiographs were assessed for migration percentage (MP), neck shaft angle (NSA), head shaft angle (HSA), and articular trochanter distance preoperatively as well as at 6 months, 1 year, 2 year, and latest follow-up postoperatively. Hips were divided into group 1 (no previous hip surgery) and group 2 (PFSH performed after hip reconstruction). Hips with 2 years of preoperative radiographic data were included in the natural history cohort.

RESULTS

Twenty-three patients (44 hips) met inclusion criteria with an average age of 7.3±1.7 years and a mean follow-up of 33.5 months. Group 1 and group 2 had 32 and 12 hips, respectively. Group 1 had significant improvement in all parameters (ΔMP=5%, ΔNSA=13 degrees, ΔHSA=15 degrees) group 2 showed improvements in NSA and HSA (ΔNSA=4 degrees ΔHSA=8 degrees) with only HSA reaching significance and MP remaining unchanged. All radiographic measurements worsened in the 2 years before surgery (N=25, natural history group) and improved after PFSH. Screw exchange occurred in 12 hips (27.2%) at an average of 33 months (range 27 to 42 mo) with 2 hips also undergoing pelvic osteotomy at that time. Three hips had a MP >50% at follow-up with 2 hips in group 1 undergoing hip reconstruction. No complications were noted.

CONCLUSION

PFSH effectively alters proximal femoral growth and can improve hip subluxation in children with CP. Screws often need to be exchanged and hips should be carefully monitored.

LEVEL OF EVIDENCE

Level III-retrospective comparative study.

Rotational abnormalities in dysplastic hips and how to predict acetabular torsion

OBJECTIVES

The aim of this study was to investigate the degree to which conventional radiography can represent the acetabular and femoral rotational alignment profile between dysplastic and borderline-dysplastic hips.

METHODS

A retrospective trial was conducted including 56 borderline-dysplastic and dysplastic hips at a mean age of 28.9 years (range from 18 to 46). Inclusion criteria consisted of symptomatic patients with hip dysplasia undergoing 2-dimensional radiography as well as computed tomography. On radiography, the lateral center edge angle, acetabular hip index, hip lateralization index, acetabular index angle, and the Sharp angle were measured, and the presence of a crossover sign was noted. In computed tomography, the full rotational profile of the lower limb was measured.

RESULTS

Significant correlations were observed in the overall analysis between the anteversion of the acetabulum and the hip lateralization index (mean 0.56, coefficient of regression (CoR) -32.35, p = 0.011) as well as the acetabular index angle with a mean of 11.50 (CoR 0.544, p = 0.018). Similar results were found in the subgroup of dysplastic hips with an acetabular index angle of 13.9 (p = 0.013, CoR 0.74). For the borderline-dysplastic group, no significant correlations between the pelvis radiography and rotational CT were seen.

CONCLUSION

Although the femoral and acetabular torsion cannot be predicted from x-rays, the anteversion of the acetabulum correlates with the acetabular index angle, the hip lateralization index, and eventually the beta angle in dysplastic hips. For borderline-dysplastic hips, such results did not show up, which strongly illustrates the need for computed tomography in these cases.

KEY POINTS

• Much of the current literature focuses on rotational alignment especially with respect to the femur and tibia in healthy patients, although little is known about the acetabular, femoral, and tibial torsion in dysplastic hips. • This is the first study showing significant correlations between the anteversion of the acetabulum and the hip lateralization index as well as the acetabular inclination angle. Also, it is the first study to provide a mechanism for estimation of the torsion of the acetabulum with plain radiography in dysplastic hips. • In borderline-dysplastic hips, no significant correlation was found, which raises the question if a simple x-ray has enough validity to address the acetabular deformity with surgery.

Surgical Treatment of Acetabular Dysplasia With Labral Tears

Acetabular dysplasia results in abnormal forces across the hip joint and can result in both labral tears and cartilage degeneration. A continuum exists from classic dysplasia to normal acetabular morphology. Diagnosis is aided by several radiographic measurements and parameters including a lateral center edge angle of less than 20°, an anterior center edge angle of less than 20°, a Sharp's angle of greater than 42°, and a Tonnis angle of greater than 10°, or version abnormalities. When patients with acetabular dysplasia present with intra-articular hip pain, skeletal maturity, and preserved radiographic joint space, a periacetabular osteotomy (PAO) is considered as a surgical treatment option when conservative measures have failed. The Bernese PAO was developed in 1984 as a way for reorienting the acetabulum to restore more normal femoral head coverage and orientation. The long-term results of this procedure have been promising with 10-year and 20-year survivorships of approximately 85% and 60%, respectively. When dysplasia is coupled with a labral tear or other intra-articular pathology including focal chondral damage, ligamentum teres tears, or capsular defects, hip arthroscopy and PAO are performed. Although there is a paucity in the literature of the long-term evidence for the combined procedure, early results indicate improved patient reported outcome measures. Appropriate treatment of borderline hip dysplasia remains controversial.

Surgical Hip Dislocation for a Diagnostic Dilemma: Differentiating Synovial Chondromatosis and Pigmented Villonodular Synovitis

Pigmented villonodular synovitis (PVNS) and synovial chondromatosis (SC) of the hip are rare synovial diseases that can induce joint destruction without early diagnosis and treatment. The extent of surgical excision is critical given the high rates of recurrence. In the presented case, a 19-year-old female was referred to our institution with progressive left hip pain and radiologic evidence of an intra-articular mass that was consistent with PVNS versus SC. Her medical history was notable for a prior excision of a fibrous lesion at an outside hospital at age 13 with persistent pain. The patient underwent a surgical hip dislocation approach to obtain near-complete visualization of the femoroacetabular joint, ensuring complete evaluation and excision. The tumor was intraoperatively diagnosed as SC and excised accordingly, during an uneventful operation. Pathology confirmed the diagnosis. The essential diagnostic and surgical steps for the management of this pelvic tumor diagnostic dilemma are described. Level of Evidence: V.

[Treatment strategies for the combination of hip dysplasia, femoroacetabular impingement and malrotation of the proximal femur : How much should be corrected?]

BACKGROUND

Hip dysplasia, FAI and femoral malrotation often occur together, resulting in mixed symptoms and severe biomechanical limitations of the hip.

OBJECTIVES

To report on the current recommendations for the best possible diagnosis and treatment strategies of combination pathologies in hip-preserving surgery.

METHODS

Review and discussion of the relevant literature with consideration of own experience in the treatment of complex combined pathomorphologies of the hip.

RESULTS

Patient history and a thorough clinical examination are key for determining the predominant pathomorphologies causing the symptoms. Standardized conventional ap pelvic and axial images of the hip are the basis for the radiological assessment of the hip, supplemented with MRI, CT and animations of the hip, depending on the case. As the pathologies influence each other functionally, a stepwise approach to treatment is recommended. The functionally most relevant pathology is treated first, followed by further corrections as needed. The primary goal is to achieve a stable hip with normal acetabular coverage, followed by an impingement-free range of motion and normalized musculoskeletal function. Care must be taken in the choice of surgical method to ensure that all pathologies can be adequately treated.

CONCLUSION

Complex, combined pathologies of the hip can be treated sufficiently with hip-preserving surgery. A thorough diagnosis is important in order to recognize the functional interaction of the different pathologies. The goal of the surgical therapy is a correctly covered, stable hip with a normal range of motion.

Predictivity of International Hip Dysplasia Institute classification in Pavlik harness treatment and correlation with Graf ultrasonographic classification

Hip ultrasonography applied according to Graf's criteria is frequently used in early diagnosis and monitoring of developmental dysplasia of the hip (DDH). Recently, the International Hip Dysplasia Institute (IHDI) classification has been proposed to be a prognostic indicator for patients with walking-age DDH. The purpose of this study is to evaluate the reliability of IHDI classification in the follow-up of patients with DDH diagnosed by ultrasonography scanning. A total of 69 hips of 38 patients (10 men, 28 women; mean age 59.9 ± 19.8 days, range 29-90 days) were diagnosed with DDH younger than 90 days of age. The AP pelvis radiographs of the patients who were diagnosed with DDH by ultrasound and classified according to the Graf method were evaluated and classified according to IHDI classification. A total of 52 hips were treated successfully with Pavlik harness treatment, 15 hips underwent closed reduction and pelvipedal casting (PPC) and 2 hips underwent open reduction and PPC after failed Pavlik harness treatment. Increasing IHDI grades correlated with the failure of Pavlik harness treatment (P = 0.001). Graf classification was not found to be predictive of successful Pavlik harness treatment (P = 0.482). There was no significant correlation between the IHDI classification and the Graf classification (Kappa = 0.079 ± 0.102, P = 0.402). The IHDI method is reliable in predicting the success of Pavlik harness treatment in patients diagnosed with DDH using the Graf method.

Irreducible Traumatic Fracture-Dislocation of the Hip with Impalement onto the Ischial Spine: A Case Report

CASE

A 45-year-old man appeared to have a central (protrusio) hip dislocation but actually had a transverse posterior wall acetabulum fracture with irreducible posterior dislocation due to impalement of the femoral head on the ischial spine. He underwent urgent open reduction on presentation and subsequent internal fixation in a staged manner. He developed avascular necrosis at 18 months postoperatively.

CONCLUSION

The nondisplaced ilioischial and iliopectineal acetabular radiographic lines were alerts that the dislocation was actually posterior. This led to further imaging before any closed reduction attempts because standard reduction maneuvers would have placed the patient at high risk for iatrogenic femoral head or neck fracture.

Chronic Pseudoaneurysm and Anterior Dislocation After Total Hip Arthroplasty Complicated by Arterial Injury: A Case Report

CASE

A 64-year-old man presented 18 months after total hip arthroplasty complicated by vascular injury with a history of leg pain, inability to mobilize, and progressive chronic leg edema. It is presumed that there was persistent subtle bleeding over time with pseudoaneurysm formation and prosthetic hip dislocation secondary to the mass effect.

CONCLUSION

Physicians should consider pseudoaneurysm as a possible diagnosis when confronted with a large intra-articular mass in the hip after a relatively short follow-up period, particularly in the context of a prior vascular injury at the time of the index procedure.

Combined acetabular and femoral neck fractures with intrapelvic femoral head dislocation: Successful staged management of a rare injury in two cases

Combined central acetabular and femoral neck fractures with intrapelvic femoral head dislocation is an infrequent situation that provides a problematic condition for surgeons attempting to reconstruct the hip joint. Herein, we report two cases involving central acetabular fracture-dislocation combined with intrapelvic dislocation of a fractured femoral neck. Each case involved associated injuries that made primary total hip arthroplasty (THA) impossible and necessitated using the fewest skin incisions possible. As a result, we first attempted a posterior acetabular fixation of both the anterior and posterior columns with intra-articular plating of the anterior column. Finally, a cementless acetabular cup was implanted. There were no complications identified during the stages of reconstruction up to and including THA. The two patients̓ final Harris Hip scores were 98 for the first patient (at five years), and 91 for the second patient (at 1 ½ years). In conclusion, staged reconstruction of the hip joint with intra-articular acetabular plating does not weaken the acetabular bone that can accept insertion of THA with cementless biological acetabular fixation without complications and with an acceptable clinical outcome up to five years.

Dual mobility hip arthroplasty: iatrogenic intraprosthetic dislocation of a 22 mm head

We describe the first intraprosthetic dislocations of a 22 mm head in a dual mobility hip replacement in the literature. This case emphasises the importance of information gathering and planning when dealing with arthroplasty complications. Furthermore, it highlights the necessity of adequate muscle relaxation and analgesia when dealing with hip dislocations. A 78-year-old patient presented to the emergency department (ED) with a spontaneous dislocation of her left dual-mobility total hip replacement 3 months after first-stage revision surgery for infection. Reduction via manipulation under analgesia was then attempted in the ED but was ultimately unsuccessful; an iatrogenic intraprosthetic dislocation of the polyethylene liner was sustained. Several factors may have contributed to liner dislocation: a failure to appreciate the implant type, multiple manipulations in ED were attempted under analgesia, but no sedation or muscle relaxation was administered to the patient. The patient subsequently underwent revision surgery.

3-D acetabular morphology of the neuromuscular hip: implications for preoperative planning

The importance of precisely understanding the pathoanatomy of acetabular dysplasia prior to surgical treatment has long been recognized. Acetabuloplasties for neuromuscular hip dysplasia have typically aimed to improve the acetabulum by increasing posterior-superior coverage, as previous three-dimensional (3-D) computed tomography (CT) studies have shown that acetabular dysplasia in neuromuscular hips is primarily in the direction of posterior-superior subluxation or dislocation. The purpose of this study was to identify differences in 3-D morphology between normal hips and dysplastic neuromuscular hips, specifically to identify areas of acetabular deficiency to guide preoperative decision-making. Patients treated for neuromuscular hip dysplasia at a single institution between 2009 and 2017 with a preoperative high-resolution pelvic CT scan (28 hips) were evaluated with custom software to measure acetabular morphology. Acetabuli were divided into equal octants; coverage angles were measured for each octant of interest. Variables were compared with age- and sex-matched normal controls (56 hips). We found a wide range of hip pathology in our study cohort. Five hips had no sectors with abnormal coverage. One hip (4%) was overcovered anteriorly. The remaining pathology was undercoverage located anteriorly [n = 7 (25%)], superiorly [n = 6 (21%)], posteriorly [n = 4 (14%)] or globally [n = 5 (18%)]. Our findings indicate that individual patients with neuromuscular acetabular dysplasia have unique deformities that do not uniformly conform to a specific area of acetabular deficiency. It is imperative to define the specific 3-D acetabular deficiency location and magnitude for accurate preoperative planning. Level of evidence: Level III.

Safe surgical hip dislocation for acetabular osteoid osteoma excision

Excision of acetabular osteoid osteoma is technically difficult. We report osteoid osteoma of the quadrilateral plate in a 9-year-old girl who presented to us with persistent nocturnal pain, limp and restricted hip joint movement. The child was investigated with CT scan, MRI and triple-phase bone scan. The 0.7 cm nidus was located in the central portion of the cancellous bone in the quadrilateral plate, 1.94 cm inferior to the triradiate cartilage. The child was operated on through the safe surgical dislocation of the left hip. The location of the lesion was gauged from the preoperative CT scan measurement data and intraoperative fluoroscopic aid. The nidus with a sclerotic rim was burred down completely. Postoperative X-ray and CT scan revealed complete excision of the tumour, and the patient was pain-free. At 18 months follow-up, the patient is completely asymptomatic and walking normally.

"Floating Hip" and "Floating Knee" Associated with Hip Dislocation, Sciatic Nerve Palsy, and Patella Fracture: A Case Report

CASE

We report a very rare case of simultaneous ipsilateral floating hip and floating knee (SIFHFK) injury with the neck of the femur and patella fracture and hip dislocation associated with sciatic nerve injury in a 45-year-old man after a road traffic accident. We adopted a staged approach for surgical fixation of the fractures after stabilization. At the latest 2 years follow-up, the patient was asymptomatic with satisfactory clinical outcome.

CONCLUSION

SIFHFK injuries present a challenging and emergent clinical scenario and require extensive clinical experience, careful planning, and multidisciplinary teamwork because of the paucity of specific treatment protocols for the treatment of this complex injury.

[Arthroscopic reduction of congenital hip dislocations in infants]

OBJECTIVE

Open reduction of congenital hip dislocations currently remains the standard treatment for those hip joints which are irreducible by closed means. The open reduction of the dislocated hip joint represents a relatively invasive surgical method. Thus, the goal was to develop a minimally invasive and safe procedure with a lower complication rate as an alternative to open reduction. This work presents the arthroscopically guided reduction of dislocated hip joints, first described in 2009, as a standardized surgical technique.

INDICATIONS

Failed closed reduction for congenital hip dislocation.

SURGICAL TECHNIQUE

Arthroscopic reduction of the dislocated femoral head using an arthroscopic two-portal technique, a high anterolateral and a medial subadductor portal. The arthroscope is inserted through the subadductor portal. The high anterolateral portal serves as working portal. Step-by-step identification and removal of obstacles to reduction such as the ligament of the femoral head, fat tissue, capsular constriction and psoas tendon. Reduction of the femoral head under arthroscopic control.

POSTOPERATIVE TREATMENT

The hip joint is retained in a hip spica cast with the legs in human position.

RESULTS

Arthroscopic hip reduction of 20 congenital hip dislocations: 13 girls and 3 boys with an average age at the time of operation of 5.8 months (3-9 months). All children had multiple, unsuccessful attempts of closed reduction by use of overhead traction, Pavlik harness or closed reduction and hip spica application. According to the Graf classification, there were 20 type IV hips. According to the radiological classification of Tönnis, there were 9 type 4, 7 type 3, and 4 type II grades. The obstacles to reduction were capsular constriction, hypertrophic ligament of the femoral head, and an extensively large pulvinar in the acetabulum. An inverted labrum was not seen in any of the cases. In contrast, in 2/3 of the cases, there was considerable retraction of the dorsal edge of the socket due to the ligament of the femoral head expanding right over it. In all cases, postreduction transinguinal ultrasound and MRI were used to check the femoral head position in the cast postoperatively. In all cases there was a deep reduction of the femoral head in the acetabulum. There were no intra- or postoperative complications such as bleeding, infections or nerve lesions. There were no cases of redislocation or decentering of the femoral head, which was also confirmed after an average follow-up of 15 months. The mean AC angle at follow-up was 24.5°. There was one coxa magna in the series and one avascular necrosis with a fragmented femoral head according to the Salter classification.

Case report of a delayed iatrogenic Pipkin type III femoral head fracture-dislocation

RATIONALE

Pipkin III femoral head fracture dislocation (FHFD) is rarely observed in clinical practice, and its outcome is alarming. A considerable proportion of Pipkin III fractures result from repeated or forceful closed reduction of an irreducible FHFD. Pipkin type III fractures pose a therapeutic challenge. Most patients underwent total hip arthroplasty.

PATIENT CONCERNS

A 34-year-old man experienced high-energy trauma to the left hip from a terrible traffic accident. Radiography and computed tomography (CT) at the local hospital revealed a left posterior FHFD. Emergency close reduction of the hip was performed.48 hours later, the patient was transferred to our institution. New radiography and CT examinations demonstrated an iatrogenic femoral neck fracture (FNF) associated with FHFD. In addition, a right talar fracture was observed.

DIAGNOSIS

Pipkin III fracture combined with contralateral talar fracture.

INTERVENTIONS

Considering his Pipkin fracture classification (Pipkin Type-III) and the time to surgery after his injury (>48 hours), the patient underwent left total hip arthroplasty uneventfully, followed by below-ankle plaster cast immobilization for his right ankle.

OUTCOMES

At the 6-month follow-up, the patient was able to walk pain-free, and plain radiographs were satisfactory, with no evidence of heterotopic ossification or osteonecrosis of the talus.

LESSONS

Before emergency closed reduction, early recognition of the unique characteristics of an irreducible FHFD is essential to avoid iatrogenic femoral neck fracture.

Femoral varus derotational osteotomy without pelvic osteotomy in nonambulatory children with cerebral palsy: Minimum 5 years follow-up

Whether femoral varus derotational osteotomy (VDRO) alone or a combination of femoral and pelvic osteotomies should be performed for hip dislocation in nonambulatory children with cerebral palsy (CP) remains controversial. Few studies have reported radiographical results after the surgical treatment in nonambulatory children with CP. This study aimed to assess the results and determine predictors indicating progressive hip subluxation and redislocation after VDRO without pelvic osteotomy. We retrospectively analyzed 22 hips in 15 nonambulatory children with CP. All patients underwent VDRO without pelvic osteotomy and were followed up for at least 5 years. The mean follow-up period was 7.3 ± 1.9 years. In radiological assessments, we investigated migration percentage (MP), center-edge angle, neck-shaft angle, teardrop distance, break in Shenton's line (SL), sharp's angle, acetabular ridge angle (ARA), and the change ratio of MP (Change MP). We classified patients with an MP of <40% at final follow-up in the Good group and those with an MP of ≥40% in the Poor group. The Good group included 10 children (14 hips), and the Poor group included 8 children (8 hips). No preoperative differences were found in the means of all the radiographical parameters. However, MP was significantly different between the groups from 1 year postoperatively. ARA showed improvement 5 years after surgery in the Good group. Change MP in the Good group was maintained from immediately after surgery to the final follow-up. Multivariate logistic regression analyses revealed that preoperative break in SL and Change MP immediately after surgery were parameters to predict MP at the final follow-up. In the receiver operating characteristic analysis, the cut-off values were estimated to be 19.2 mm for preoperative SL and 79.0% for Change MP immediately after surgery. Within 7.3 years of follow-up, 63.6% of the patients who underwent VDRO without pelvic osteotomy had good results. Preoperative SL and postoperative Change MP can be considered as predictors of postoperative subluxation and/or dislocation.

Failure of Hip Reconstruction in Children With Cerebral Palsy: What Are the Risk Factors?

BACKGROUND

The rates and risk factors contributing to failure after hip reconstruction among patients with cerebral palsy (CP) are not well established. In analyzing a large cohort of children with CP who underwent hip reconstruction, the objectives of this study are to establish (1) the failure rates and (2) associated risk factors.

METHODS

This retrospective study included chart and radiographic review of patients between the ages of 1 to 18, with a diagnosis of CP, who underwent a hip reconstructive procedure at a single children's hospital over a 9-year period (2010 to 2018). Patients without at least 2 years of follow-up were excluded. Age at time of surgery, sex, Gross Motor Function Classification System (GMFCS), procedure(s) performed, preoperative migration percentage (MP), neck-shaft angle, and acetabular index (AI) were recorded. Failure was defined as need for revision surgery or a MP >50% on follow-up radiographs. Logistic regression and multiple-variable regression-type models were used to test for significance of risk factors.

RESULTS

Of the 291 hips in 179 patients (102 males, 77 females) that met inclusion criteria, 38 hips (13%) failed. Significant differences in the failure group were seen in age at time of surgery (6.2±3.2 vs. 8.1±3.2; P<0.001), preoperative MP (62.3±28.7 vs. 39.9±24.1%; P<0.001) and preoperative neck-shaft angle (164.9±8.2 vs. 157.3±15.6 degrees; P<0.001). Age below 6 at time of surgery significantly increased failure rate (26% vs. 6.3%, P<0.001) as did preoperative MP >70% (28.9% vs. 9.9%, P<0.001). Receiving an acetabular osteotomy was protective against failure (9.1% vs. 16.9%, P=0.048), particularly in patients with a preoperative AI >25° (odds ratio=0.236; confidence interval: 0.090-0.549).

CONCLUSIONS

In this case series, failure after hip reconstruction for children with CP was determined to be 13.1%. There was a higher risk associated with age under 6 at time of surgery or a preoperative MP >70%. Correction of acetabular dysplasia when AI is more than 25 degrees with acetabular osteotomy at time of hip reconstruction, exerted a protective effect against subsequent failure.

LEVEL OF EVIDENCE

Level III-retrospective case series.

Interobserver and Intraobserver Reliability in the Salter Classification of Avascular Necrosis of the Femoral Head in Developmental Dysplasia of the Hip

BACKGROUND

Avascular necrosis (AVN) of the femoral head is a concerning complication that can result from treatments for developmental dysplasia of the hip (DDH). AVN can lead to degenerative osteoarthritis, persistent acetabular dysplasia, reduced function, and continuing hip pain. The incidence of AVN reported in the DDH literature is widely varied (0% to 73%). This variability may arise from lack of consensus on what constitutes true AVN in this patient population, and lack of clear criteria provided in studies reporting incidence rates.

METHODS

A multicentre, prospective database of infants diagnosed with DDH between 2010 and 2014 from 0 to 18 months of age was analyzed for patients treated by closed reduction (CR). Twelve pediatric orthopaedic surgeons completed 2 rounds of AVN assessments. Deidentified anteroposterior radiographs at most recent follow-up were provided to surgeons along with patient age at radiographic assessment, length of follow-up, ands affected hip. Ten of 12 surgeons completed a third round of assessments where they were provided with 1 to 2 additional radiographs within the follow-up period. Radiographic criteria for total AVN described by Salter and colleagues were used. Surgeons rated the presence of AVN as "yes" or "no" and kappa values were calculated within and between rounds.

RESULTS

A total of 69 hips in 60 patients were assessed for AVN a median of 22 months (range: 12 to 36) post-CR. Interobserver kappa values for rounds 1, 2, and 3 were 0.52 (range: 0.11 to 0.90), 0.61 (range: 0.21 to 0.90), and 0.53 (range: 0.10 to 0.79), respectively. Intraobserver agreement for AVN diagnosis was an average of 0.72 (range: 0.31 to 0.96).

CONCLUSIONS

Despite using the most commonly referenced diagnostic criteria, radiographic diagnosis of AVN following CR in DDH patients demonstrated only moderate agreement across surgeons. The addition of sequential radiographs did not improve cross-observer reliability, and while substantial agreement was seen within observers, the range of intraobserver kappa values was large.

LEVEL OF EVIDENCE

Level I-diagnostic study.

Is Anterior Rotation of the Acetabulum Necessary to Normalize Joint Contact Pressure in Periacetabular Osteotomy? A Finite-element Analysis Study

BACKGROUND

Inappropriate sagittal plane correction can result in an increased risk of osteoarthritis progression after periacetabular osteotomy (PAO). Individual and postural variations in sagittal pelvic tilt, along with acetabular deformity, affect joint contact mechanics in dysplastic hips and may impact the direction and degree of acetabular correction. Finite-element analyses that account for physiologic pelvic tilt may provide valuable insight into the effect of PAO on the contact mechanics of dysplastic hips, which may lead to improved acetabular correction during PAO.

QUESTIONS/PURPOSES

We performed virtual PAO using finite-element models with reference to the standing pelvic position to clarify (1) whether lateral rotation of the acetabulum normalizes the joint contact pressure, (2) risk factors for abnormal contact pressure after lateral rotation of the acetabulum, and (3) whether additional anterior rotation of the acetabulum further reduces contact pressure.

METHODS

Between 2016 and 2020, 85 patients (92 hips) underwent PAO to treat hip dysplasia. Eighty-two patients with hip dysplasia (lateral center-edge angle < 20°) were included. Patients with advanced osteoarthritis, femoral head deformity, prior hip or spine surgery, or poor-quality images were excluded. Thirty-eight patients (38 hips) were eligible to participate in this study. All patients were women, with a mean age of 39 ± 10 years. Thirty-three women volunteers without a history of hip disease were reviewed as control participants. Individuals with a lateral center-edge angle < 25° or poor-quality images were excluded. Sixteen individuals (16 hips) with a mean age of 36 ± 7 years were eligible as controls. Using CT images, we developed patient-specific three-dimensional surface hip models with the standing pelvic position as a reference. The loading scenario was based on single-leg stance. Four patterns of virtual PAO were performed in the models. First, the acetabular fragment was rotated laterally in the coronal plane so that the lateral center-edge angle was 30°; then, anterior rotation in the sagittal plane was added by 0°, 5°, 10°, and 15°. We developed finite-element models for each acetabular position and performed a nonlinear contact analysis to calculate the joint contact pressure of the acetabular cartilage. The normal range of the maximum joint contact pressure was calculated to be < 4.1 MPa using a receiver operating characteristic curve. A paired t-test or Wilcoxon signed rank test with Bonferroni correction was used to compare joint contact pressures among acetabular positions. We evaluated the association of joint contact pressure with the patient-specific sagittal pelvic tilt and acetabular version and coverage using Pearson or Spearman correlation coefficients. An exploratory univariate logistic regression analysis was performed to identify which of the preoperative factors (CT measurement parameters and sagittal pelvic tilt) were associated with abnormal contact pressure after lateral rotation of the acetabulum. Variables with p values < 0.05 (anterior center-edge angle and sagittal pelvic tilt) were included in a multivariable model to identify the independent influence of each factor.

RESULTS

Lateral rotation of the acetabulum decreased the median maximum contact pressure compared with that before virtual PAO (3.7 MPa [range 2.2-6.7] versus 7.2 MPa [range 4.1-14 MPa], difference of medians 3.5 MPa; p < 0.001). The resulting maximum contact pressures were within the normal range (< 4.1 MPa) in 63% of the hips (24 of 38 hips). The maximum contact pressure after lateral acetabular rotation was negatively correlated with the standing pelvic tilt (anterior pelvic plane angle) (ρ = -0.52; p < 0.001) and anterior center-edge angle (ρ = -0.47; p = 0.003). After controlling for confounding variables such as the lateral center-edge angle and sagittal pelvic tilt, we found that a decreased preoperative anterior center-edge angle (per 1°; odds ratio 1.14 [95% CI 1.01-1.28]; p = 0.01) was independently associated with elevated contact pressure (≥ 4.1 MPa) after lateral rotation; a preoperative anterior center-edge angle < 32° in the standing pelvic position was associated with elevated contact pressure (sensitivity 57%, specificity 96%, area under the curve 0.77). Additional anterior rotation further decreased the joint contact pressure; the maximum contact pressures were within the normal range in 74% (28 of 38 hips), 76% (29 of 38 hips), and 84% (32 of 38 hips) of the hips when the acetabulum was rotated anteriorly by 5°, 10°, and 15°, respectively.

CONCLUSION

Via virtual PAO, normal joint contact pressure was achieved in 63% of patients by normalizing the lateral acetabular coverage. However, lateral acetabular rotation was insufficient to normalize the joint contact pressure in patients with more posteriorly tilted pelvises and anterior acetabular deficiency. In patients with a preoperative anterior center-edge angle < 32° in the standing pelvic position, additional anterior rotation is expected to be a useful guide to normalize the joint contact pressure.

CLINICAL RELEVANCE

This virtual PAO study suggests that biomechanics-based planning for PAO should incorporate not only the morphology of the hip but also the physiologic pelvic tilt in the weightbearing position in order to customize acetabular reorientation for each patient.

The association the patient-reported outcomes after periacetabular osteotomy with radiographic features: a short-term retrospective study

BACKGROUND

Bernese periacetabular osteotomy (PAO) is an effective treatment for patients with developmental dysplasia of the hip (DDH). PAO has been widely used in China, but few follow-up outcomes have been reported in the international community. Moreover, the risk factors affecting patient-reported outcomes have not been discussed in recent studies. In this study, patient-reported outcomes after PAO were reported, and risk factors affecting patient-reported outcomes were analyzed.

METHODS

Patients who underwent PAO for DDH from January 2014 to January 2020 were selected as the study subjects, and 66 hips were included in the analysis after screening (59 patients, with an average follow-up time of 3.01 years). The Harris Hip Score (HHS) and International Hip Outcome Instrument-12 (iHOT-12) were used to assess hip function and patient quality of life. The changes of preoperative and latest follow-up HHSs less than 9 were defined as symptomatic hips, that is, an adverse outcome; otherwise, the score indicates preserved hips. Also, the changes of preoperative and latest follow-up iHOT-12 were defined as symptomatic hips and preserved hips. Multivariate logistic regression analysis was used to predict the risk factors influencing the patient-reported outcomes, and receiver operating characteristic (ROC) curve analysis was performed on the risk factors to determine their sensitivity, specificity and cutoff value.

RESULTS

Clinical outcome analysis demonstrates marked improvements in patient-reported outcomes. The multivariate logistic regression analysis showed that when the postoperative LCEA was > 38°, adverse outcomes were much more likely. However, a Tönnis angle of - 10° to 0° was a protective factor. In addition, hips with fair or poor joint congruency were more likely to develop negative outcomes. The ROC curve analysis showed that the optimal thresholds for the LCEA and Tönnis angles used to predict outcomes after PAO were 38.2° and - 9°, respectively. Based on the results of the ROC curve analysis, among hips with poor or fair joint congruency preoperatively treated by surgeons who obtained the improper postoperative LCEAs and Tönnis angles, bad patient-reported outcomes will most likely be obtained.

CONCLUSIONS

Our results demonstrate marked improvements in patient-reported outcomes. Among hips with preoperative excellent or good joint congruency treated by experienced surgeons who obtain the proper postoperative LCEA and Tönnis angles, good patient-reported outcomes can be expected.

Changes in Muscle Volume and Composition After Treatment of Hip Dysplasia with Periacetabular Osteotomy

BACKGROUND

Periacetabular osteotomy (PAO) is a common treatment for pre-arthritic hip dysplasia in young adults. The purpose of this study was to better understand changes in muscle volume and composition after PAO visualized using magnetic resonance imaging (MRI).

METHODS

A prospectively collected series of individuals that underwent PAO for hip dysplasia were reviewed to identify subjects with pre- and postoperative MRI. In our practice, MRI was obtained preoperatively and greater than 6 months after PAO for persistent hip pain. MRI sequences were selected to optimize visualization of the muscle volume, fatty infiltration, and hip joint cartilage. MRI images were selected at predetermined bony landmarks and analyzed using 3D Slicer (©2021, www.slicer.org) software to measure muscle diameter and calculate muscle cross-sectional area (CSA) in 17 individual muscles surrounding the hip. Muscle atrophy was graded using the Goutallier classification for fatty infiltration and acetabular cartilage condition was graded using the Outerbridge classification. We compared pre- and postoperative muscle area and composition as well as cartilage for each case.

RESULTS

A series of six female patients met our inclusion criteria. Mean age was 26 years at time of surgery. All cases had MRI sequences adequate for muscle volume measurements. Fatty infiltration and cartilage changes were recorded in four subjects with appropriate MRI sequences. Separating muscle groups, external rotators underwent the largest volume increase. Hip flexors demonstrated mild volume decrease. CSA change among external rotators averaged +12%, hip flexors -9.3%, and hip abductors -9.2% after PAO. All muscles had either the same or increased fatty infiltration after surgery, with gluteus medius and iliacus undergoing the most average increase. Similarly, cartilage condition worsened by a small margin in this series.

CONCLUSION

Our results provide preliminary indication that PAO may have noticeable effects on muscle characteristics and cartilage in the early postoperative period. This was a limited case series of subjects with adequate pre- and post-operative MRI imaging.Level of Evidence: IV.

Ganz osteotomy for treatment of hip dysplasia through intra-pelvic approach. Early results

Ganz periacetabular osteotomy (PAO) is a technically demanding surgical procedure. It requires cutting around the acetabulum to mobilize it under fluoro- scopic control. The radiolucent table and good quality imaging are mandatory to perform this osteotomy in a safe way. Modification of Ganz osteotomy was developed a with minimal soft tissue exposure using intra-pelvic approach which allows direct visualization of the quadrilateral plate. The purpose of the present study was to review the early results in the initial group of patients who had this procedure. The Ganz PAO was performed on 8 cases painful dysplastic hips, using the intra-pelvic approach through the Pfannenstiel incision. All of the osteotomies were performed under fluoroscopic control and direct visualizing the osteotomy site from the same incision. The acetabular fragment was medialized and redirected anterolaterally then fixed with 3 screws. The pre-operative Harris hip score mean was 66.8 and improved to be 92.7 (p value <0.0005) and this was statistically significant. Radiologically the CEA improved in the pre-operative X-ray from mean of 13.12 degree to 28.37 degrees (p value <0.0005) and this was statistically significant. Painful dysplastic hips should be treated before function becomes seriously impaired. The Ganz osteotomy through an intra-pelvic approach, can be done with minimal exposure to radiation in a relatively short time.

Severe Open Dislocation of the Hip with Exposed Femoral Head: A Case Report

CASE

A 54-year-old woman was brought to our emergency department with an inferomedial open hip dislocation without fracture secondary to a railway trauma. We performed hip reduction, wound debridement, and stabilization with external fixation. After 7 months, hip arthroplasty was performed for severe hip instability and avascular necrosis of the femoral head.

CONCLUSION

Open hip dislocation is an uncommon injury that is caused by high-energy trauma. It may be associated with serious management problems and complications, including infection and avascular necrosis of the femoral head.

Neglected acetabular fracture with hip dislocation in a 34-year-old subject treated with total hip arthroplasty: our experience

Neglected hip fracture-dislocations are rare but still possible clinical situations, especially in developing countries. Some authors described skeletal traction and open reduction with internal fixation as a treatment for the abovementioned conditions. Despite the poor literature about this topic, total hip arthroplasty (THA) may be a feasible option in the treatment of neglected hip fracture-dislocations. We present a case of a 34-year-old Moroccan man reporting a 1-year neglected acetabular fracture with hip dislocation successfully treated with THA. The patient showed a significant improvement of pain, range of motion and his quality of life at 45 days. Our experience shows how a neglected acetabular fracture with hip dislocation can be successfully treated with THA. Considering the complexity of these cases, an accurate preoperative planning is mandatory and the prosthetic components' choice must be customised to the patient.

Cam morphology but neither acetabular dysplasia nor pincer morphology is associated with osteophytosis throughout the hip: findings from a cross-sectional study in UK Biobank

OBJECTIVES

To examine whether acetabular dysplasia (AD), cam and/or pincer morphology are associated with radiographic hip osteoarthritis (rHOA) and hip pain in UK Biobank (UKB) and, if so, what distribution of osteophytes is observed.

DESIGN

Participants from UKB with a left hip dual-energy X-ray absorptiometry (DXA) scan had alpha angle (AA), lateral centre-edge angle (LCEA) and joint space narrowing (JSN) derived automatically. Cam and pincer morphology, and AD were defined using AA and LCEA. Osteophytes were measured manually and rHOA grades were calculated from JSN and osteophyte measures. Logistic regression was used to examine the relationships between these hip morphologies and rHOA, osteophytes, JSN, and hip pain.

RESULTS

6,807 individuals were selected (mean age: 62.7; 3382/3425 males/females). Cam morphology was more prevalent in males than females (15.4% and 1.8% respectively). In males, cam morphology was associated with rHOA [OR 3.20 (95% CI 2.41-4.25)], JSN [1.53 (1.24-1.88)], and acetabular [1.87 (1.48-2.36)], superior [1.94 (1.45-2.57)] and inferior [4.75 (3.44-6.57)] femoral osteophytes, and hip pain [1.48 (1.05-2.09)]. Broadly similar associations were seen in females, but with weaker statistical evidence. Neither pincer morphology nor AD showed any associations with rHOA or hip pain.

CONCLUSIONS

Cam morphology was predominantly seen in males in whom it was associated with rHOA and hip pain. In males and females, cam morphology was associated with inferior femoral head osteophytes more strongly than those at the superior femoral head and acetabulum. Further studies are justified to characterise the biomechanical disturbances associated with cam morphology, underlying the observed osteophyte distribution.

What Are the Rate and Risk Factors for Developing a Complication With the Pavlik Method for the Treatment of Hip Dysplasia?

BACKGROUND

The Pavlik method for the treatment of developmental dysplasia of the hip (DDH) has been proven successful for over 85 years. The high success rate and reproducibility have made it the mainstay of treatment.

METHODS

We performed a retrospective cohort study of patients with DDH treated with the Pavlik method between September 2016 and August 2018 with at least 24 months of follow up in a single academic center. We excluded patients with neuromuscular conditions, teratologic dislocations, and arthrogryposis. We identified and included a total of 307 patients in the analysis. There were 66 patients with dysplasia, 97 with instability, and 144 with a dislocation. Data collected included age at initiation of the Pavlik method, diagnosis (isolated dysplasia, subluxation, or dislocation), duration of treatment, follow up duration and any complication. At final follow up, anteroposterior radiographs of the pelvis were used to determine the Severin classification.

RESULTS

Major complications were proximal femoral growth disturbance (5.8%) and femoral nerve palsy (0.98%). Multivariate analysis showed that an initial diagnosis of a dislocated hip (odds ratio, 2.20; P<0.01), was significantly associated with developing a complication. At final follow up, we found Severin type I or II radiographic findings in 100% of patients with dysplasia, 95% of patients with instability and 54% of patients with dislocation (P=0.001).

CONCLUSIONS

Complications are not entirely uncommon when the Pavlik method is used for the treatment of DDH. The overall rate of major complications was 7%. The Pavlik method is safe, and independent risk factors for complications were being over 5 months of age and having a dislocated hip at initial presentation.

LEVEL OF EVIDENCE

Level IV-cohort study.

2D Ultrasound Validation to Assess the Accuracy of Hip Displacement Measurement: A Phantom Study

Hip displacement is a common orthopedic abnormality in children with cerebral palsy and is assessed on anteroposterior pelvic radiographs during surveillance. Repeated exposure to ionizing radiation is a major concern of cancer risks for children. Ultrasound (US) has been proposed to image the hips. The severity of hip displacement is measured by the Reimers' migration percentage (MP), which is calculated by the ratio of the femoral head distance from the acetabulum to the width of the femoral head. Methods have been published to estimate MP from the US hip images in literature; however, validation for accuracy has not been reported. This study aimed to determine the accuracy of the 2D ultrasound techniques using two 3D printed hip phantoms with known MP values. The MPs estimated from the US images were compared with those measured from the X-ray images. Based on the experimental results, the US measurements had a maximum absolute discrepancy of 2.2% as compared to 9.8% from the X-ray measurements for the MP. The study on phantoms has showed the proposed US approach is promising with better accuracy and without ionizing radiation.Clinical Relevance - If the accuracy is proved to be at least as good as the current X-ray gold standard, the proposed US method will provide a modality of choice to pediatric patients for hip displacement diagnostics and hip surveillance, especially those with cerebral palsy. The method will be free of ionizing radiation and therefore significantly improve the pediatric patient care.

The Femoral Head-Shaft Angle Is Not a Predictor of Hip Displacement in Children Under 5 Years With Cerebral Palsy: A Population-based Study of Children at GMFCS Levels III-V

BACKGROUND

The aim of this study was to evaluate whether the femoral head-shaft angle (HSA) is a predictor of hip displacement in children with cerebral palsy (CP).

METHODS

The patients were recruited from a population-based hip surveillance program. Inclusion criteria were age under 5 years, bilateral CP, Gross Motor Function Classification System (GMFCS) levels III-V, and migration percentage (MP) of both hips <40% at the primary radiograph. With these criteria, 101 children (61 boys) were included. GMFCS was level III in 26 patients, level IV in 23, and level V in 52. An anteroposterior radiograph of the pelvis was taken at diagnosis and at the last follow-up. Only the worst hip of each patient (the hip with the largest MP) was used for the analyses.

RESULTS

The mean age at the primary radiograph was 2.4 years (range, 0.8 to 4.9 y). The mean primary HSA was 171.0 degrees (range, 152 to 190 degrees). The mean follow-up time was 4.3 years (range, 0.9 to 11.8 y). The mean MP at the primary radiograph was 17.5% (range, 0% to 39%) and at the last follow-up 41.9% (range, 0% to 100%). At that point, MP was <40% in 54 hips and ≥40% in 47 hips. There was no significant difference in primary HSA between patients with final MP<40% and those with final MP≥40% (170.8 and 171.3 degrees, respectively; P=0.761). At the last follow-up, the mean HSA was significantly larger in hips with final MP≥40% than in hips with final MP<40% (171.1 vs. 167.4 degrees; P=0.029).

CONCLUSIONS

There was a markedly increased valgus position of the proximal femur in nonambulatory children with CP. However, the primary HSA in children below 5 years of age was not a predictor of later hip displacement, defined as MP≥40%.

CLINICAL RELEVANCE

Measurement of HSA is not necessary in routine hip surveillance in children below 5 years.

LEVEL OF EVIDENCE

Level I-investigating a diagnostic test.

Posterior hip dislocation associated with concomitant ipsilateral femoral head and shaft fractures: an unusual combination of injuries

The combination of posterior hip dislocation with an ipsilateral femoral head and shaft fractures is unusual. While cases of concomitant fractures of femoral head and shaft have been previously reported, the treatment of such injuries is challenging. Presence of an associated hip dislocation further complicates the matter. A timely diagnosis and treatment are crucial to have a good outcome.We are presenting the case of a 20-year-old man who sustained a traumatic posterior hip dislocation with ipsilateral femoral shaft and femur head fractures. After reducing the hip, we fixed the femoral shaft with a retrograde femur nail and the femoral head by the trochanteric flip approach in the same sitting. The patient returned to his pre-injury occupation after 4 months. He has been doing well until his last follow-up, 1 year after the surgery, thus emphasising the utility of following basic principles of trauma management in the management of unusual injuries.

Does Patient-specific Functional Pelvic Tilt Affect Joint Contact Pressure in Hip Dysplasia? A Finite-element Analysis Study

BACKGROUND

Although individual and postural variations in the physiologic pelvic tilt affect the acetabular orientation and coverage in patients with hip dysplasia, their effect on the mechanical environment in the hip has not been fully understood. Individual-specific, finite-element analyses that account for physiologic pelvic tilt may provide valuable insight into the contact mechanics of dysplastic hips, which can lead to further understanding of the pathogenesis and improved treatment of this patient population.

QUESTION/PURPOSE

We used finite-element analysis to ask whether there are differences between patients with hip dysplasia and patients without dysplasia in terms of (1) physiologic pelvic tilt, (2) the pelvic position and joint contact pressure, and (3) the morphologic factors associated with joint contact pressure.

METHODS

Between 2016 and 2019, 82 patients underwent pelvic osteotomy to treat hip dysplasia. Seventy patients with hip dysplasia (lateral center-edge angle ≥ 0° and < 20° on supine AP pelvic radiographs) were included. Patients with advanced osteoarthritis, femoral head deformity, prior hip or supine surgery, or poor-quality imaging were excluded. Thirty-two patients (32 hips) were eligible to this finite-element analysis study. For control groups, we reviewed 33 female volunteers without a history of hip disease. Individuals with frank or borderline hip dysplasia (lateral center-edge angle < 25°) or poor-quality imaging were excluded. Sixteen individuals (16 hips) were eligible as controls. Two board-certified orthopaedic surgeons measured sagittal pelvic tilt (the angle between the anterior pelvic plane and vertical axis: anterior pelvic plane [APP] angle) and acetabular version and coverage using pelvic radiographs and CT images. Intra- and interobserver reliabilities, evaluated using the kappa value and intraclass correlation coefficient, were good or excellent. We developed individual-specific, finite-element models using pelvic CT images, and performed nonlinear contact analysis to calculate the joint contact pressure on the acetabular cartilage during the single-leg stance with respect to three pelvic positions: standardized (anterior pelvic plane), supine, and standing. We compared physiologic pelvic tilt between patients with and without dysplasia using a t-test or the Wilcoxon rank sum test. A paired t-test or the Wilcoxon signed rank test with a Bonferroni correction was used to compare joint contact pressure between the three pelvic positions. We correlated joint contact pressure with morphologic parameters and pelvic tilt using the Pearson or the Spearman correlation coefficients.

RESULTS

The APP angle in the supine and standing positions varied widely among individuals. It was greater in patients with hip dysplasia than in patients in the control group when in the standing position (3° ± 6° versus -2° ± 8°; mean difference 5° [95% CI 1° to 9°]; p = 0.02) but did not differ between the two groups when supine (8° ± 5° versus 5° ± 7°; mean difference 3° [95% CI 0° to 7°]; p = 0.06). The mean pelvic tilt was 6° ± 5° posteriorly when shifting from the supine to the standing position in patients with hip dysplasia. The median (range) maximum contact pressure was higher in dysplastic hips than in control individuals (in standing position; 7.3 megapascals [MPa] [4.1 to 14] versus 3.5 MPa [2.2 to 4.4]; difference of medians 3.8 MPa; p < 0.001). The median maximum contact pressure in the standing pelvic position was greater than that in the supine position in patients with hip dysplasia (7.3 MPa [4.1to 14] versus 5.8 MPa [3.5 to 12]; difference of medians 1.5 MPa; p < 0.001). Although the median maximum joint contact pressure in the standardized pelvic position did not differ from that in the standing position (7.4 MPa [4.3 to 15] versus 7.3 MPa [4.1 to 14]; difference of medians -0.1 MPa; p > 0.99), the difference in the maximum contact pressure varied from -3.3 MPa to 2.9 MPa, reflecting the wide range of APP angles (mean 3° ± 6° [-11° to 14°]) when standing. The maximum joint contact pressure in the standing position was negatively correlated with the standing APP angle (r = -0.46; p = 0.008) in patients with hip dysplasia.

CONCLUSION

Based on our findings that individual and postural variations in the physiologic pelvic tilt affect joint contact pressure in the hip, future studies on the pathogenesis of hip dysplasia and joint preservation surgery should not only include the supine or standard pelvic position, but also they need to incorporate the effect of the patient-specific pelvic tilt in the standing position on the biomechanical environment of the hip.

CLINICAL RELEVANCE

We recommend assessing postural change in sagittal pelvic tilt when diagnosing hip dysplasia and planning preservation hip surgery because assessment in a supine or standard pelvic position may overlook alterations in the hip's contact mechanics in the weightbearing positions. Further studies are needed to elucidate the effect of patient-specific functional pelvic tilt on the degeneration process of dysplastic hips, the acetabular reorientation maneuver, and the clinical result of joint preservation surgery.

A new modification of the Trapdoor Procedure without surgical hip dislocation in the management of patients with osteonecrosis of the femoral head: A retrospective case series

OBJECTIVE

The aim of this paper was to investigate the mid-term results of a modified Trapdoor procedure that can allow grafting of the femoral head without surgical hip dislocation in the management of patients with osteonecrosis of the femoral head.

METHODS

16 hips of 12 patients (7 female, 5 male; mean age = 38.5 ± 10.7) surgically treated by the new modification of Trapdoor procedure were retrospectively reviewed and included in the study. Based on the Association Research Circulation Osseous (ARCO) classification system, seven hips (43.7%) were stage 2, and nine hips (56.3%) were stage 3. The mean follow-up was 48.4 ± 25.7 months (range = 12-107). All the patients were evaluated postoperatively at the 6th week, 3rd month, 6th month, 1st year, and annually thereafter until their final follow-up. Clinical assessment was performed using the Harris Hip scoring (HHS) system, Non-Arthritic Hip score (NAHS) and Visual analogue pain scale (VAS). At the final follow-up, degenerative changes were examined according to the Kellgren-Lawrence scale.

RESULTS

ThemeanHHS increased from53.43 ± 9.0 (range = 36-67) preoperatively to 83.81 ± 6.1 (range = 72-95) at the final follow-up (P < 0,001). Themean NAHS increased from 51.5 ± 8.2 (range = 36.25-61.25) preoperatively to 86 ± 3.2 (range = 81.5-90) (P < 0,001) at the final follow-up. The mean preoperative VAS decreased from 7.85 ± 0.9 (range = 6.45-9.5) to 3.05 ± 0.9 (range = 1.6-5.2) (P < 0,001) at the final follow-up. 13 hips demonstrated 80 and higher scores according toHHS. In the remaining three hips (ARCOstage 3), the mean postoperative HHS, NAHS, and VAS scores were 76, 82, and 3,2 respectively. According to Kellgren-Lawrence scale, three hips (18,75%) were determined as grade 0, 10 hips (62.5%) as grade 1, and 3 hips (18.75%) as grade 2.

CONCLUSION

The Modified Trapdoor procedure without surgical hip dislocation seems to be a suitable technique with favorable clinical outcomes for the treatment of ARCO stage 2 and stage 3 osteonecrosis of the femoral head.

LEVEL OF EVIDENCE

Level IV, Therapeutic Study.

Hip Morphology in Early-stage LCPD: Is There an Argument for Anatomic-specific Containment?

BACKGROUND

Early containment surgery has become increasingly popular in Legg-Calvé-Perthes Disease (LCPD), especially for older children. These procedures treat the proximal femur, the acetabulum, or both, and most surgeons endorse the same surgical option regardless of an individual patient's anatomy. This "one-surgery-fits-all" approach fails to consider potential variations in baseline anatomy that may make one option more sensible than another. We sought to describe hip morphology in a large series of children with newly diagnosed LCPD, hypothesizing that variation in anatomy may support the concept of anatomic-specific containment.

METHODS

A retrospective review of a prospectively collected multicenter database was conducted for patients aged 6 to 11 at diagnosis. To assess anatomy before significant morphologic changes secondary to the disease itself, only patients in Waldenström stages IA/IB were included. Standard hip radiographic measurements including acetabular index, lateral center-edge angle, proximal femoral neck-shaft angle (NSA), articulotrochanteric quartiles, and extrusion index (EI) were made on printed anteroposterior pelvis radiographs. Age-specific percentiles were calculated for these measures using published norms. Significant outliers (≤10th/≥90th percentile) were reported where applicable.

RESULTS

A total of 168 patients with mean age at diagnosis of 8.0±1.3 years met inclusion criteria (81.5% male). Mean acetabular index for the entire cohort was 16.8±4.1 degrees; 58 hips (34.5%) were significantly dysplastic compared with normative data. Mean lateral center-edge angle was 15.9±5.2 degrees at diagnosis; 110 (65.5%) were ≤10th percentile indicating dysplasia (by this metric). Mean NSA overall was 136.5±7.0 degrees. Fifty-one (30.4%) and 20 (11.9%) hips were significantly varus (≤10th percentile) or valgus (≥90th percentile), respectively. Thirty-five hips (20.8%) were the third articulo-trochanteric quartiles or higher suggesting a higher-riding trochanter at baseline. Mean EI was 15.5%±9.0%, while 63 patients (37.5%) had an EI ≥20%.

CONCLUSIONS

The present study finds significant variation in baseline anatomy in children with early-stage LCPD, including a high prevalence of coexisting acetabular dysplasia as well as high/low NSAs. These variations suggest that the "one-surgery-fits-all" approach may lack specificity for a particular patient; a potentially wiser option may be an anatomic-specific containment operation (eg, acetabular-sided osteotomy for coexisting dysplasia, varus femoral osteotomy for valgus NSA).

LEVEL OF EVIDENCE

Level IV.

Deep Learning Artificial Intelligence Model for Assessment of Hip Dislocation Risk Following Primary Total Hip Arthroplasty From Postoperative Radiographs

BACKGROUND

Dislocation is a common complication following total hip arthroplasty (THA), and accounts for a high percentage of subsequent revisions. The purpose of this study is to illustrate the potential of a convolutional neural network model to assess the risk of hip dislocation based on postoperative anteroposterior pelvis radiographs.

METHODS

We retrospectively evaluated radiographs for a cohort of 13,970 primary THAs with 374 dislocations over 5 years of follow-up. Overall, 1490 radiographs from dislocated and 91,094 from non-dislocated THAs were included in the analysis. A convolutional neural network object detection model (YOLO-V3) was trained to crop the images by centering on the femoral head. A ResNet18 classifier was trained to predict subsequent hip dislocation from the cropped imaging. The ResNet18 classifier was initialized with ImageNet weights and trained using FastAI (V1.0) running on PyTorch. The training was run for 15 epochs using 10-fold cross validation, data oversampling, and augmentation.

RESULTS

The hip dislocation classifier achieved the following mean performance (standard deviation): accuracy = 49.5 (4.1%), sensitivity = 89.0 (2.2%), specificity = 48.8 (4.2%), positive predictive value = 3.3 (0.3%), negative predictive value = 99.5 (0.1%), and area under the receiver operating characteristic curve = 76.7 (3.6%). Saliency maps demonstrated that the model placed the greatest emphasis on the femoral head and acetabular component.

CONCLUSION

Existing prediction methods fail to identify patients at high risk of dislocation following THA. Our radiographic classifier model has high sensitivity and negative predictive value, and can be combined with clinical risk factor information for rapid assessment of risk for dislocation following THA. The model further suggests radiographic locations which may be important in understanding the etiology of prosthesis dislocation. Importantly, our model is an illustration of the potential of automated imaging artificial intelligence models in orthopedics.

LEVEL OF EVIDENCE

Level III.

Periacetabular Osteotomy and Femoral Head Allograft for Hip Dysplasia and Femoral Head Cyst: A Case Report

CASE

A 34-year-old woman with developmental dysplasia of the hip (DDH) presented with chronic left hip pain related to a femoral head cyst. The patient strongly preferred a joint-preserving option. Periacetabular osteotomy (PAO) has shown reliable options for managing DDH, and femoral head fresh osteochondral allograft (FOCA) can be performed for cysts. We performed these procedures concomitantly for the first time. At 1-year follow-up, the patient had functional, pain-free motion and high satisfaction.

CONCLUSION

PAO and femoral head FOCA can be performed concomitantly with a common, anterior hip approach. They are a viable, joint-preserving option for patients with DDH and osteochondral lesions.