[Definition of hip dysplasia in 2023 : Signs of macro and micro instability]. / Definition der Hüftdysplasie im Jahr 2023 : Zeichen der Makro- und Mikroinstabilität.

BACKGROUND: Hip dysplasia is a complex static-dynamic pathology leading to chronic joint instability and osteoarthritis. Because our understanding of the underlying pathomorphologies of hip dysplasia, both on the macro and micro levels, has evolved, an updated definition is needed. QUESTION: What is the definition of hip dysplasia in 2023? METHODS: By summarizing and reviewing relevant literature, we provide an up-to-date definition of hip dysplasia with a guide to appropriately making the diagnosis. RESULTS: In addition to the pathognomonic parameters, supportive and descriptive indicators, as well as secondary changes are used to fully characterize instability inherent in hip dysplasia. The primary diagnostic tool is always the plain anteroposterior pelvis radiograph, which can be supplemented by additional investigations (MRI of the hip with intraarticular contrast agent; CT) if necessary. CONCLUSION: The complexity, subtlety, and diversity of the pathomorphology of residual hip dysplasia requires careful, multilevel diagnosis and treatment planning in specialized centers.

Children's Hip Predictive (CHiP) Score: A Triage Tool for Hip Dislocation in Children Referred With Suspected Hip Dysplasia.

BACKGROUND: A fundamental tenent of treating developmental dysplasia of the hip is to identify patients with dislocated hips early so as to avoid the long-term sequelae of late diagnosis. The aim of this study was to develop a readily useable triage tool for patients with suspected hip dislocation, based on the clinical history and examination findings of the referring practitioner. METHODS: All primary care referrals (n=934) over a 3-year period for suspected developmental dysplasia of the hip to a tertiary pediatric center were evaluated. Defined parameters with respect to history and clinical examination were evaluated. Multivariable logistic regression was used to establish predictors of hip dislocation, and from this a predictive model was derived which incorporated significant predictors of dislocation. An illustrative nomogram translated this predictive model into a usable numerical scoring system called the Children's Hip Prediction score, which estimates probability of hip dislocation. RESULTS: There were 97 dislocated hips in 85 patients. The final predictive model included age, sex, family history, breech, gait concerns, decreased abduction, leg length discrepancy, and medical/neurological syndrome. The area under receiver operating curve for the model is 0.761. A Children's Hip Prediction score of≥5 corresponds to a sensitivity of 76.3% and a score of≥15 has a specificity of 97.8%, corresponding to an odds ratio of 27.3 for increased risk of dislocation. CONCLUSION: We found that a novel clinical prediction score, based on readily available history and examination parameters strongly predicted risk of dislocations in hip dysplasia referral. It is hoped that this tool could be utilized to optimize resource allocation and may be of particular benefit in less well-resourced health care systems. LEVEL OF EVIDENCE: Level II.

[Treatment of hip dysplasia in young adults]. / Behandlung der Hüftgelenkdysplasie beim jungen Erwachsenen.

Developmental dysplasia of the hip (DDH) is one of the most common disorders of hips in children. The deformity can remain asymptomatic into adolescence and adulthood; however, it is considered to be a form of prearthritis and is the main cause of premature osteoarthritis of the hip. The deformity affects the acetabulum but can also be accompanied by changes in the shape of the proximal femur. If conservative treatment for mild DDH is insufficient, or in cases of moderate to severe DDH, operative treatment should be carried out, for example by corrective osteotomy of the pelvis and/or the proximal femur and hip arthroscopy may be considered adjunctively in order to resolve the prearthritis and prevent premature osteoarthritis of the hip. This manuscript elucidates the deformity, the diagnostic measures required to make the diagnosis and the treatment options available for prevention of arthritis.

Australian hip surveillance guidelines at 10 years: New evidence and implementation.

Optimum management of hip displacement in children with cerebral palsy (CP) is facilitated by an approach that focuses on anticipatory and preventive measures. Hip surveillance programs for children with CP were developed at the beginning of the new millennium, with the purpose of identifying hip displacement sufficiently early to permit a choice of effective management options. In the early years, hip surveillance was guided by epidemiological analysis of population-based studies of prevalence. In Australia, a National Hip Surveillance in CP Working Group was first convened in 2005. This resulted in a 2008 Consensus Statement of recommendations published and endorsed by Australasian Academy of Cerebral Palsy and Developmental Medicine (AusACPDM). The group undertook that the recommendations should be reviewed every 5 years to ensure currency and congruency with the emerging evidence base. As new evidence became available, hip surveillance guidelines developed, with the most recent 2020 Australian Hip Surveillance Guidelines endorsed by the AusACPDM. Implementing comprehensive hip surveillance programs has now been shown to improve the natural history of hip dislocations and improve quality of life. Standardised hip surveillance programs can also facilitate planning for multicentre research through harmonisation of data collection. This, in turn, can help with the identification of robust new evidence that is based on large cohort or population studies. Here a review of evidence informing the updated 2020 Hip Surveillance Guidelines is presented.

Age at the Time of Surgery Is Not Predictive of Early Patient-Reported Outcomes After Periacetabular Osteotomy.

BACKGROUND: The clinical success of periacetabular osteotomy (PAO) for the treatment of symptomatic acetabular dysplasia is well-documented. Conflicting evidence exists regarding the correlation of age with clinical outcomes. Hip disability and Osteoarthritis Outcome Score - global (HOOSglobal) is a recently validated patient-reported outcome measure following PAO. The purpose of this study is to asses HOOSglobal and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores at early follow-up based on age at the time of PAO. METHODS: A prospective multicenter cohort of 391 patients undergoing PAO with minimum 2-year follow-up (average 4.71 years) were identified. Patients were categorized into 4 age groups: <20 years (N = 131), 20-29 (N = 102), 30-39 (N = 65), and ≥40 (N = 34). A 4 × 2 repeated measures analysis of variance (Age Group × Time) was used to compare preoperative and postoperative HOOSglobal and WOMAC scores between age groups. A multiple linear regression was used to identify predictors of postoperative HOOSglobal scores. RESULTS: HOOSglobal and WOMAC scores increased across all age groups; however, a statistically greater increase in preoperative to postoperative HOOSglobal and WOMAC scores was found in those ≥40 years compared to those <20 (P< .002), 20-29 (P = .01), and 30-39 years (P = .02). Higher preoperative HOOSglobal scores were predictive of greater postoperative HOOSglobal scores (P < .001) but age (P = .65), gender (P = .80), body mass index (P = .50), and Tönnis Classification (P = .07) were not independent predictors of 1-year outcomes. CONCLUSION: The absence of differences in early postoperative patient-reported outcomes across multiple age ranges emphasizes that PAO in the setting of symptomatic acetabular dysplasia can be successful regardless of patient age alone. Therefore, age alone might not be an appropriate selection criterion when evaluating surgical candidates for PAO. LEVEL OF EVIDENCE: II.

Risk factors for hip dislocation in dyskinetic cerebral palsy.

PURPOSE: To investigate the risk factors for hip displacement in patients with dyskinetic cerebral palsy (DCP). METHODS: We evaluated 81 patients with DCP, 45 males and 36 females, aged 10-22 years, risk factors for hip displacement were evaluated using multivariate logistic regression analysis with primary brain lesions, Gross Motor Function Classification System (GMFCS) level, gestational age, birth weight, Cobb's angle, and complication of epilepsy as independent factors. Hip displacement was defined as migration percentage >30%. Primary brain lesions were classified into globus pallidus (GP), thalamus and putamen (TP), and others using brain magnetic resonance imaging (MRI). Perinatal and clinical features were compared between patients with GP lesions and those with TP lesions. RESULTS: Hip displacement was observed in 53 patients (67%). Higher GMFCS levels (p = 0.013, odds ratio [OR] 2.6) and the presence of GP lesions (p = 0.04, OR 16.5) were independent risk factors for hip displacement. Patients with GP lesions showed significantly higher GMFCS levels, more frequent hip displacement, and lower gestational age and birth weight than those with TP lesions. CONCLUSION: Primary brain lesion location may be an important factor in predicting hip displacement among patients with DCP. Appropriate risk assessment using brain MRI may contribute to the early detection and intervention of hip displacement because brain lesion location can be assessed during infancy before GMFCS level is decided.

Effect of clinician's experience and expertise on the inter- and intra-observer reliability of hip migration index in children with cerebral palsy: A STROBE-compliant retrospective study.

ABSTRACT: Few studies have investigated the reliability of Reimers' hip migration percentage (RMP) in children with cerebral palsy (CP). Most studies on the topic reflected rating results of physician with a similar level of experience from the same expertise. This study aimed to determine the effect of clinician's experience and expertise on the intra-and inter-observer reliability of RMP.In this retrospective observational study, hip radiographs of children with CP were identified. 5 observers with different degrees of working experience from 3 different clinical fields, including orthopedics, radiology, and physical medicine and rehabilitation, performed all RMP measurements. All measurements were repeated 6 weeks later by the same observers. Inter- and intra-observer reliability for RMP measurements were assessed using Intraclass Correlation Coeficient (ICC), calculated from 2 sets of repeated measurements on a subset of 50 hips, with a 6 week apart for each observer.Fifty hip radiographs of 25 children with CP (10 females and 15 males; mean age: 6 years; age range: 2-8 years) were examined in the current study. No significant differences existed in intra-and inter-observer measurements. Excellent intra-observer reliability was observed between the 2 separate measurements for each observer, with a mean ICC of 0.976 (range: 0.956-0.989; P < .001). Among 5 observers, inter-observer reliability was excellent for the 2 separate RMP measurements, with the mean ICC minimally increasing between the 2 measurement periods (mean ICC: 0.928, range: 0.838-0.979 and mean ICC: 0.936, range: 0.861-0.983, respectively) (P < .001).Clinician's experience and expertise may not affect inter-and intra-observer reliability of RMP measurements.

Inferior hip dislocation in a 16 year old.

Inferior hip dislocations are the least common form of hip dislocation. They require a high energy mechanism of injury and are often associated with other traumatic limb and life threatening injuries. This article reviews the case of a 16 year old male who presented to the emergency department (ED) following a high speed motor vehicle crash. On arrival he was diagnosed with a right inferior hip dislocation among other critical findings. This case report provides a brief literature review of this poorly studied clinical entity and seeks to educate physicians providing emergency, traumatic, orthopedic or critical care to patients who present with acute inferior hip dislocations.

Development of a diagnostic algorithm identifying cases of dislocation after primary total hip arthroplasty-based on 31,762 patients from the Danish Hip Arthroplasty Register.

Background and purpose - Dislocation of total hip arthroplasties (THA) is often treated with closed reduction and traditionally not registered in orthopedic registers. This study aimed to create an algorithm designed to identify cases of dislocations of THAs with high sensitivity, specificity, and positive predictive value (PPV) based on codes from the Danish National Patient Register (DNPR).Patients and methods - All patients (n = 31,762) with primary osteoarthritis undergoing THA from January 1, 2010 to December 31, 2014 were included from the Danish Hip Arthroplasty Register (DHR). We extracted available data for every hospital contact in the DNPR during a 2-year follow-up period, then conducted a comprehensive nationwide review of 5,096 patient files to register all dislocations and applied codes.Results - We identified 1,890 hip dislocations among 1,094 of the included 31,762 THAs. More than 70 different diagnoses and 55 procedural codes were coupled to the hospital contacts with dislocation. A combination of the correct codes produced a sensitivity of 63% and a PPV of 98%. Adding alternative and often applied codes increased the sensitivity to 91%, while the PPV was maintained at 93%. Additional steps increased sensitivity to 95% but at the expense of an unacceptable decrease in the PPV to 82%. Specificity was, in all steps, greater than 99%.Interpretation - The developed algorithm achieved high and acceptable values for sensitivity, specificity, and predictive values. We found that surgeons in most cases coded correctly. However, the codes were not always transferred to the discharge summary. In perspective, this kind of algorithm may be used in Danish quality registers.

Is paracetamol responsible for fatal acute liver failure in pediatric patients after hip dysplasia surgery?

OBJECTIVE: It is well known that local complications, such as avascular necrosis and arthrosis can develop after surgery for developmental dysplasia of the hip (DDH). Thus far, systemic complications that may develop in such cases have not been identified in the literature. This study is the first case series to evaluate acute liver failure (ALF) development after DDH surgery in pediatric patients. PATIENTS AND METHODS: Six patients, five female and one male, who underwent DDH surgery were selected for this study. Perioperative fasting time, laboratory values, treatments, histopathological evaluations, and prognoses after ALF in these patients were evaluated retrospectively. RESULTS: All the patients were administered paracetamol and sevoflurane in therapeutic doses. The patients were referred postoperatively to our pediatric emergency department after 5 ± 1.67 days (range = 3-7 days) on average. The average perioperative fasting time was 9.3 ± 0.82 hours (range = 8-10 hours). Due to the very high aminotransferases and use of paracetamol, intravenous N-acetylcysteine was administered alongside supportive treatments to all the patients. After liver transplantation, two of three patients with grade 3 encephalopathy, died in the early postoperative period. Histopathological evaluations of the three patients' explants were compatible with toxic hepatitis due to paracetamol. CONCLUSIONS: Paracetamol is a commonly used analgesic after pediatric surgery. The therapeutic dose of paracetamol remains uncertain in children who have been fasting for a long time and have been exposed to hepatotoxic drugs due to previous surgery. In conclusion, caution should be exercised in the use of paracetamol in children with DDH who will undergo surgery, and careful perioperative clinical and laboratory monitoring for ALF is essential.

A novel arthroscopic classification of labral tear in hip dysplasia.

BACKGROUND: Acetabular labral tears cause of pain in patients with symptomatic hip dysplasia. To date, no structured grading system has been developed to evaluate labral tears in these patients. The present study describes a new system of grading labral tears in patients with acetabular dysplasia. METHODS: The data of 66 patients who underwent hip arthroscopy for symptomatic hip dysplasia from March 2014 to February 2018 were reviewed. Labral tears were classified into four groups, based on the occurrence of chondrolabral junction (CLJ) disruption, capsulolabral recess (CLR) disruption, and labral displacement. Labral tears without instability were classified as grade 1 or 2. Partial delamination or blistering of the labrum with minimal fraying at the CLJ was classified as grade 1, whereas labral tears with CLJ disruption were classified as grade 2. Unstable labral tears with CLR disruption followed by CLJ disruption, but without labral displacement, were classified as grade 3, whereas unstable labral tears with CLR and CLJ disruption, but with labral displacement, were classified as grade 4. The radiological and clinical characteristics of patients in each grade were determined including by simple radiographs and MRI/MR arthrography, as were concomitant findings, including rupture of the ligamentum teres, articular cartilage damage, and presence of a paralabral cyst. The surgical options selected for each grade and clinical outcomes, including modified Harris hip scores (mHHS) and Western Ontario and McMaster Universities Osteoarthritis index (WOMAC) scores, were evaluated. Spearman's correlation analyses were performed to assess whether labral tear grade correlated with baseline characteristics, the incidence of concomitant injuries, and the severity of osteoarthritis (OA). The Wilcoxon test for paired data was performed to compare treatment results with pain scores. RESULTS: The study cohort included six men and 53 women of mean ± SD age 39.9 ± 13.0 years (range, 15-66 years). Of the 66 hips, seven (10.6%), 10 (15.2%), 30 (45.5%), and 19 (28.8%) were classified as grades 1-4, respectively. Symptom duration (P = 0.017), preoperative Tönnis OA grade (P < 0.001), cartilage damage (P < 0.001), and the presence of a paralabral cyst (P = 0.001) correlated significantly with baseline tear grade. In all groups, mHHS and WOMAC scores improved after surgical treatment. CONCLUSIONS: Arthroscopic findings of labral tears in patients with hip dysplasia differed from the conventional classification. The classification system proposed in this study will likely be useful for determining the degree of labral tear in patients with hip dysplasia and for predicting treatment outcomes.

The fate of femoral head autograft in acetabular reconstruction in dysplastic hips at midterm.

PURPOSE: To evaluate the acetabular cup and graft survival in patients who underwent total hip arthroplasty (THA) with the diagnosis of dysplastic hip osteoarthritis and received a femoral head autograft due to acetabular coverage deficiency. METHODS: Between January 2005 and December 2016, 83 hip prostheses of 80 patients who underwent THA using femoral head autografts and were followed up for at least 2 years were retrospectively evaluated. Seventy-four hips of the remaining 71 patients (57 female (80%)) were included. Mean patient age at surgery was 51 ± 16 (range 18-76) years. The mean follow-up duration was 76 ± 25 (range 25-161) months. Acetabular inclination and graft thickness, contact length, percentage of coverage, and graft resorption were examined on postoperative and final follow-up radiographs. The presence of a radiolucent area around the acetabular and femoral components indicating loosening was also evaluated. RESULTS: The mean postoperative acetabular component inclination was 44 ± 5.1° (range 30-48°) with mean graft coverage of 34 ± 4.8% (range 24-46%). In all patients, autograft union with the pelvis was seen and the lateral overflow was remodeled. Fifteen patients (20%) underwent revision surgery due to aseptic acetabular component loosening in four, nontraumatic recurrent dislocations in eight, periprosthetic infection in one, acetabular component protrusion in one, and traumatic hip dislocation in one. CONCLUSION: In patients with osteoarthritis secondary to developmental hip dysplasia, the use of femoral head autografts to eliminate acetabular coverage deficiency during THA achieves acceptable midterm postoperative radiological outcomes. Increased acetabular bone stock may be beneficial in possible future revision surgeries.

Investigation of the priority among the roentgenogram measurements in acetabular dysplasia.

PURPOSE: There are many radiographic parameters to evaluate developmental dysplasia of the hip joint (DDH); however, the priority between the parameters is unclear. We evaluated the priority of radiographic parameters in DDH. METHODS: We retrospectively reviewed the radiographs of 82 consecutive patients aged above 85 years without hip osteoarthritis (OA; no osteoarthritis (NO) group), and 28 patients with early stage hip OA were set as the control group (OA group). We used the linear discriminant analysis (LDA) to consider the priority of the following parameters: acetabular roof obliquity (ARO), center-edge (CE) angle, Sharp angle, acetabular head index (AHI), and acetabular depth ratio (ADR). RESULTS: The LDA of five different parameters revealed that the NO and OA groups could be almost distinguished with 83.6% accuracy (p < 0.0001, Wilks' lambda test). The standardized scoring coefficients were as follows: ARO, -0.23; CE, -0.43; Sharp, -0.29; AHI, 0.97; and ADR, 0.11. The AHI was particularly noticeable in the NO group. CONCLUSION: Dissociation of the AHI in the OA group was significantly higher than that of the other parameters in the OA group compared to the parameters in the NO group. A small AHI may be a risk parameter for hip OA due to DDH.

The utility of hip arthroscopy for patients with painful borderline hip dysplasia.

PURPOSE: We measured the width of the acetabular labra in, and the clinical outcomes of, patients with borderline hip dysplasia (HD) who underwent arthroscopy. METHODS: A total of 1436 patients who underwent hip arthroscopy to treat symptomatic, acetabular labral tears were enrolled. From this cohort, we extracted a borderline HD group (162 cases). Lateral labral widths were evaluated using preoperative magnetic resonance imaging scans. Clinical data including the modified Harris hip score (mHHS), non-arthritic hip score (NAHS), hip outcome score-activity of daily living (HOS-ADL) score, visual analog scale (VAS) pain score, and Tönnis grade were collected. In addition, patient satisfaction with arthroscopy outcomes was rated. All complications and reoperations were noted. RESULTS: The mean follow-up time was 87.4 months. The lateral labral width was 7.64 mm in those with normal hips and 7.73 mm in borderline HD patients, respectively (p = 0.870). The Tönnis grade progressed mildly from 0.46 to 0.76 (p = 0.227). At the last follow-up, clinical outcome scores (mHHS, NAHS, and HOS-ADL scores) and the VAS score were improved (p < 0.001). The mean patient satisfaction was scored at 8.2. The reoperation rate was higher in those who underwent labral debridement (25.6%) than labral repair (4.1%). CONCLUSIONS: The lateral labral width did not differ significantly between the borderline HD group and the nondysplastic control group. Arthroscopy relieved the symptoms of painful borderline HD and did not accelerate osteoarthritis. Therefore, if such patients do not respond to conservative treatment, hip arthroscopy can be considered for further treatment.

Surgical management of chronic pelvic instability following periacetabular osteotomy nonunion.

INTRODUCTION: Periacetabular osteotomy (PAO) is an established treatment for symptomatic acetabular dysplasia in skeletally mature individuals without arthritis. Pelvic nonunion and associated stress fractures are under-reported. Nonunited stress fractures can cause continued buttock pain and pelvic instability. The aim of this study is to report on our experience managing patients with ongoing pain following nonunion of PAO. PATIENTS AND METHODS: 8 patients presented to a tertiary referral pelvic service with symptomatic PAO nonunion between 2015-2018. All patients underwent open reduction internal fixation of the superior pubic ramus nonunion, with ipsilateral iliac autograft, at an average of 48.1 (15-82) months following initial osteotomy. Demographic and perioperative data were recorded. Follow-up was on average to 9.9 months, once union was confirmed radiographically. RESULTS: All patients were female and average age was 31.8 (18-41) years. In 7/8 (87.5%) patients a modified Stoppa approach was successfully utilised. 1 patient required an ilioinguinal approach due to the amount of rotational correction. All patients went on to union at the superior pubic ramus and reported improvement in mechanical symptoms. 5/8 (62.5%) patients were noted to develop union of the posterior column or inferior pubic ramus stress fracture indirectly. 2/8 (25%) patients developed progression of intra-articular pain, despite restoration of pelvic stability. 1 patient required intraoperative transfusion due to femoral vein injury. There were no other complications seen in this series. CONCLUSIONS: To our knowledge, this is the largest case series of surgically managed PAO nonunion. Pelvic instability resulting from nonunion and stress fracture can be satisfactorily addressed by mobilising, grafting and plating the nonunion at the superior pubic ramus. The modified Stoppa approach is suitable in most cases, allowing excellent exposure whilst minimising the insult to soft tissues. The altered anatomy of the pelvis following PAO should be anticipated to reduce the risk to nearby neurovascular structures.

Ipsilateral femoral neck and intertrochanteric fractures with posterior dislocation of the hip: A report of two cases.

Traumatic hip dislocation usually occurs in young patients, with the increasing number of high-energy injuries, and 62-93% of reported adult traumatic hip dislocations were caused by high-speed motor vehicle crashes. However, ipsilateral femoral neck fractures and intertrochanteric fractures with posterior dislocation of the hip are extremely rare, and this injury poses a challenge to orthopaedic surgeons. Here, we report two cases of simultaneous ipsilateral femoral neck fracture, intertrochanteric fracture and posterior dislocation of the hip joint in young patients who were treated with proximal femoral locking compression plate (PFLCP). The long-term follow-up (one patient was followed up for 3 years and the other for 7 years) showed that these patients had excellent functional outcomes with near-normal ranges of hip movement. The authors believe that using smaller plates with the lateral PFLCP is an acceptable method to treat this injury in young patients.

Hip displacement in Wolf-Hirschhorn syndrome: Report on three cases and review of associated musculoskeletal pathologies.

Wolf-Hirschhorn syndrome is a rare genetic disease caused by a chromosomal deletion of the distal short arm of Chromosome 4. It is associated with multisystem abnormalities, including delayed growth, characteristic facial features, epilepsy, and skeletal abnormalities. We report three patients who developed hip displacement, and describe the occurrence of delayed and nonunion in patients who underwent corrective proximal femoral osteotomy for hip displacement. We also performed a literature review identifying common musculoskeletal presentations associated with the condition. Patients with Wolf-Hirschhorn Syndrome are at risk of hip displacement (subluxation), and we would advocate annual hip surveillance in this patient group.

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

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

Hip displacement and dislocation in a total population of children with cerebral palsy in Scotland.

AIMS: The purpose of this study was to compare the prevalence of hip displacement and dislocation in a total population of children with cerebral palsy (CP) in Scotland before and after the initiation of a hip surveillance programme. PATIENTS: A total of 2,155 children with CP are registered in the Cerebral Palsy Integrated Pathway Scotland (CPIPS) surveillance programme, which began in 2013. Physical examination and hip radiological data are collected according to nationally agreed protocols. METHODS: Age, Gross Motor Function Classification System (GMFCS) level, subtype of CP, migration percentage (MP), and details of hip surgery were analyzed for all children aged between two and 16 years taken from a time of census in March 2019 and compared to the same data from the initial registration of children in the CPIPS. Displacement of the hip was defined as a MP of between 40% and 99%, and dislocation as a MP of 100%. RESULTS: A total of 1,646 children were available for analysis at the time of the census and 1,171 at their first registration in CPIPS. The distribution of age, sex, and GMFCS levels were similar in the two groups. The prevalence of displacement and dislocation of the hip before surveillance began were 10% (117/1,171) and 2.5% (29/1,171) respectively, and at the time of the census were 4.5% (74/1,646) and 1.3% (21/1,646), respectively. Dislocation was only seen in GMFCS levels IV and V and displacement seen in 90.5% (67/74) of these levels and 9.5% (7/74) in levels I to III. In total, 138 children had undergone hip surgery during the study period. The hip redisplaced after the initial surgery in 15 children; seven of these had undergone a second procedure and at the time of the census the hips in all seven had a MP < 40. CONCLUSION: Hip surveillance appears to be effective and has reduced the prevalence of hip displacement by over half and dislocation almost by half in these children. Cite this article: Bone Joint J 2020;102-B(3):383-387.

Accuracy of leg length and femoral offset restoration after total hip arthroplasty with the utilisation of an intraoperative calibration gauge.

BACKGROUND: Offset and leg length (LL) restoration are critical for the achievement of a stable, well-functioning hip following total hip arthroplasty (THA). Several techniques are described in the literature, including a hip calibration gauge. We question whether meticulous preoperative planning of a specific surgical technique in combination with the utilisation of a calibration gauge can provide an accurate offset and LL restoration. METHODS: Retrospective review of 101 unilateral THAs via a posterior approach by a single surgeon. Preoperative radiographic LL and offset were radiographically calculated. Intraoperatively prior to hip dislocation a calibration gauge was used to measure LL and offset with a pin inserted into the iliac crest acting as a static referencing point. All had pelvis x-ray performed 6 weeks postoperatively. A literature review was conducted to establish average postoperative LL/offset values for statistical comparison. RESULTS: The average absolute postoperative leg-length discrepancy (LLD) was 2.51 mm compared to preoperatively 3.54 mm (p = 0.018). A total of 93.1% and 100% had LLD of ⩽5 mm and ⩽10 mm, respectively. The mean postoperative offset difference was 2.39 mm. The investigated LLD and offset results were comparable with literature data of studies utilising an intraoperative measuring device. LLD was significantly decreased when compared to a free-hand technique (LLD 4.42 mm, p < 0.001). CONCLUSION: The technique utilising preoperative templating, intraoperative offset verification together with the use of hip calibration gauge yielded accurate LLD and offset restoration as in the literature. Precise offset restoration, which often is a neglected issue, can lead to better abductor vector restoration, hip function and less pain.