Corona mortis: clinical evaluation of prevalence, anatomy, and relevance in anterior approaches to the pelvis and acetabulum.

PURPOSE: To evaluate the clinical prevalence, characteristics, and relevance of the corona mortis (CM) in anterior approaches to the pelvis and acetabulum. METHODS: Retrospective analysis of 185 theater reports from patients (73 females; mean age 62.8 ± 17.2 years) who underwent surgeries for pelvic ring injuries, acetabular fractures, or combined injuries using anterior approaches (Modified Stoppa or Pararectus) at our institution between 01/2008 to 12/2022. During procedures, the CM was routinely identified, evaluated, and occluded. Bilateral exposure of the superior pubic branch in 25 cases led to 210 hemipelvises analyzed. EXCLUSIONS: CM not mentioned in report and revisions via the initial approach. RESULTS: In the 210 hemipelvises examined, the prevalence of any CM vessel was 81% (170/210). Venous anastomoses were found in 76% of hemipelvises (159/210), arterial in 22% (47/210). Sole venous anastomoses appeared in 59% (123/210), sole arterial in 5% (11/210). Both types coexisted in 17% (36/210), while 19% (40/210) had none. A single incidental CM injury occurred without significant bleeding. In ten cases, trauma had preoperatively ruptured the CM, but bleeding was readily managed. Females had a significantly higher CM prevalence than males (p = 0.001). CONCLUSION: Our findings show a CM prevalence aligning more with anatomical studies than prior intraoperative series. Although we observed one incidental and ten trauma-related CM injuries, we did not encounter uncontrollable bleeding. Our data suggest that in anterior pelvic approaches, when the CM is actively identified and occluded, it is not associated with bleeding events, despite its high prevalence.

A Cam Morphology Develops in the Early Phase of the Final Growth Spurt in Adolescent Ice Hockey Players: Results of a Prospective MRI-based Study.

BACKGROUND: Cam morphologies seem to develop with an increased prevalence in adolescent boys performing high-impact sports. The crucial question is at what age the cam morphology actually develops and whether there is an association with an aberration of the shape of the growth plate at the cam morphology site. QUESTIONS/PURPOSES: (1) What is the frequency of cam morphologies in adolescent ice hockey players, and when do they appear? (2) Is there an association between an extension of the physeal growth plate and the development of a cam morphology? (3) How often do these players demonstrate clinical findings like pain and lack of internal rotation? METHODS: A prospective, longitudinal MRI study was done to monitor the proximal femoral development and to define the appearance of cam morphologies in adolescent ice hockey players during the final growth spurt. Young ice hockey players from the local boys' league up to the age of 13 years (mean age 12 ± 0.5 years) were invited to participate. From 35 players performing on the highest national level, 25 boys and their parents consented to participate. None of these 25 players had to be excluded for known disease or previous surgery or hip trauma. At baseline examination as well as 1.5 and 3 years later, we performed a prospective noncontrast MRI scan and a clinical examination. The three-dimensional morphology of the proximal femur was assessed by one of the authors using radial images of the hip in a clockwise manner. The two validated parameters were: (1) the alpha angle for head asphericity (abnormal > 60°) and (2) the epiphyseal extension for detecting an abnormality in the shape of the capital physis and a potential correlation at the site of the cam morphology. The clinical examination was performed by one of the authors evaluating (1) internal rotation in 90° of hip and knee flexion and (2) hip pain during the anterior impingement test. RESULTS: Cam morphologies were most apparent at the 1.5-year follow-up interval (10 of 25; baseline versus 1.5-year follow-up: p = 0.007) and a few more occurred between 1.5 and 3 years (12 of 23; 1.5-year versus 3-year follow-up: p = 0.14). At 3-year follow-up, there was a positive correlation between increased epiphyseal extension and a high alpha angle at the anterosuperior quadrant (1 o'clock to 3 o'clock) (Spearman correlation coefficient = 0.341; p < 0.003). The prevalence of pain on the impingement test and/or restricted internal rotation less than 20° increased most between 1.5-year (1 of 25) and the 3-year follow-up (6 of 22; 1.5-year versus 3-year follow-up: p = 0.02). CONCLUSION: Our data suggest that a cam morphology develops early during the final growth spurt of the femoral head in adolescent ice hockey players predominantly between 13 to 16 years of age. A correlation between an increased extension of the growth plate and an increased alpha angle at the site of the cam morphology suggests a potential underlying growth disturbance. This should be further followed by high-resolution or biochemical MRI methods. Considering the high number of cam morphologies that correlated with abnormal clinical findings, we propose that adolescents performing high-impact sports should be screened for signs of cam impingement, such as by asking about hip pain and/or examining the patient for limited internal hip rotation. LEVEL OF EVIDENCE: Level I, prognostic study.

[Torsional deformities of the femur in patients with femoroacetabular impingement : Dynamic 3D impingement simulation can be helpful for the planning of surgical hip dislocation and hip arthroscopy]. / Femorale Torsionsfehler bei Patienten mit femoroazetabulärem Impingement : Die dynamische 3D Impingementsimulation kann bei der Planung der chirurgischen Hüftluxation und der Hüftarthroskopie behilflich sein.

BACKGROUND: Torsional deformities of the femur include femoral retrotorsion and increased femoral torsion, which are possible causes for hip pain and osteoarthritis. For patients with femoroacetabular impingement (FAI), torsional deformities of the femur represent an additional cause of FAI in addition to cam and pincer-type FAI. OBJECTIVES: The aim of this article is to provide an overview of measurement techniques and normal values of femoral torsion. The clinical presentation, possible combinations and surgical therapy of patients with torsional deformities of the femur will be discussed. METHODS: For measurement of femoral torsion, CT or MRI represent the method of choice. The various definitions should be taken into account, because they can lead to differing values and misdiagnosis. This is the case especially for patients with high femoral torsion. Dynamic 3D impingement simulation using 3D-CT can help to differentiate between intra und extra-articular FAI. RESULTS AND DISCUSSION: Femoral retrotorsion (< 5°) can lead to anterior intra- and extraarticular (subspine) FAI, between the anterior iliac inferior spine (AIIS) and the proximal femur. Increased femoral torsion (> 35°) can lead to posterior intra- and extra-articular ischiofemoral FAI, between the lesser/greater trochanter and the ischial tuberosity. During clinical examination, a patient with femoral retrotorsion exhibits loss of internal rotation and a positive anterior impingement test. Hips with increased femoral torsion show high internal rotation if examined in prone position and have a positive FABER and posterior impingement test. During surgical therapy for patients with torsional deformities, intra and extra-articular causes for FAI in addition to cam and pincer-deformities should be considered. In addition to hip arthroscopy and surgical hip dislocation, also femoral rotational or derotational osteotomies should be evaluated during surgical planning of these patients.

Effects of Prodromal Stage and Untreated Psychosis on Subsequent Psychopathology of Schizophrenia: A Path Analysis.

BACKGROUND: To examine psychopathology present under prolonged antipsychotic treatment in schizophrenia and to analyse their relationship to both the duration of the prodromal stage (DPS; time between onset of first unspecific psychological symptoms and first schizophrenic symptoms) and the duration of untreated psychosis (DUP; time between the onset of psychosis and the initiation of antipsychotic treatment). METHODS: The psychopathology of 93 patients was assessed cross-sectionally using the Scales for the Assessment of Negative and Positive Symptoms and the Brief Psychiatric Rating Scale. DPS and DUP were assessed by means of the patient records and the Interview for the Retrospective Assessment of the Onset and Course of Schizophrenia and Other Psychoses. A path analysis using maximum likelihood estimation was conducted with the program Analysis of Moment Structures for Windows. RESULTS: The resulting path model indicated that DPS was predictive for a more severe negative symptomatology in schizophrenia, whereas DUP was associated with a more severe positive symptomatology in the long-term. Furthermore, DUP showed an inverse correlation with the age of the patients at the onset of both first unspecific psychological symptoms and first schizophrenic symptoms. CONCLUSION: A long prodromal stage suggests an increased risk of a long-term progression with negative symptoms in schizophrenia, whereas a delayed start of antipsychotic treatment could lead to an increased manifestation and severity of positive symptoms in the long term. These results underline the need to shorten the duration of the prodrome by an early detection and adequate intervention in patients with increased risk to develop psychosis.

How Does the dGEMRIC Index Change After Surgical Treatment for FAI? A Prospective Controlled Study: Preliminary Results.

BACKGROUND: Delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) allows an objective, noninvasive, and longitudinal quantification of biochemical cartilage properties. Although dGEMRIC has been used to monitor the course of cartilage degeneration after periacetabular osteotomy (PAO) for correction of hip dysplasia, such longitudinal data are currently lacking for femoroacetabular impingement (FAI). QUESTIONS/PURPOSES: (1) How does the mean acetabular and femoral dGEMRIC index change after surgery for FAI at 1-year followup compared with a similar group of patients with FAI treated without surgery? (2) Does the regional distribution of the acetabular and femoral dGEMRIC index change for the two groups over time? (3) Is there a correlation between the baseline dGEMRIC index and the change of patient-reported outcome measures (PROMs) at 1-year followup? (4) Among those treated surgically, can dGEMRIC indices distinguish between intact and degenerated cartilage? METHODS: We performed a prospective, comparative, nonrandomized, longitudinal study. At the time of enrollment, the patients' decision whether to undergo surgery or choose nonoperative treatment was not made yet. Thirty-nine patients (40 hips) who underwent either joint-preserving surgery for FAI (20 hips) or nonoperative treatment (20 hips) were included. The two groups did not differ regarding Tönnis osteoarthritis score, preoperative PROMs, or baseline dGEMRIC indices. There were more women (60% versus 30%, p = 0.003) in the nonoperative group and patients were older (36 ± 8 years versus 30 ± 8 years, p = 0.026) and had lower alpha angles (65° ± 10° versus 73° ± 12°, p = 0.022) compared with the operative group. We used a 3.0-T scanner and a three-dimensional dual flip-angle gradient-echo technique for the dGEMRIC technique for the baseline and the 1-year followup measurements. dGEMRIC indices of femoral and acetabular cartilage were measured separately on the initial and followup radial dGEMRIC reformats in direct comparison with morphologic radial images. Regions of interest were placed manually peripherally and centrally within the cartilage based on anatomic landmarks at the clockface positions. The WOMAC, the Hip disability and Osteoarthritis Outcome Score, and the modified Harris hip score were used as PROMs. Among those treated surgically, the intraoperative damage according to the Beck grading was recorded and compared with the baseline dGEMRIC indices. RESULTS: Although both the operative and the nonoperative groups experienced decreased dGEMRIC indices, the declines were more pronounced in the operative group (-96 ± 112 ms versus -16 ± 101 ms on the acetabular side and -96 ± 123 ms versus -21 ± 83 ms on the femoral side in the operative and nonoperative groups, respectively; p < 0.001 for both). Patients undergoing hip arthroscopy and surgical hip dislocation experienced decreased dGEMRIC indices; the decline in femoral dGEMRIC indices was more pronounced in hips after surgical hip dislocation (-120 ± 137 ms versus -61 ± 89 ms, p = 0.002). In the operative group a decline in dGEMRIC indices was observed in 43 of 44 regions over time. In the nonoperative group a decline in dGEMRIC indices was observed in four of 44 regions over time. The strongest correlation among patients treated surgically was found between the change in WOMAC and baseline dGEMRIC indices for the entire joint (R = 0.788, p < 0.001). Among those treated nonoperatively, no correlation between baseline dGEMRIC indices and change in PROMs was found. In the posterosuperior quadrant, the dGEMRIC index was higher for patients with intact cartilage compared with hips with chondral lesions (592 ± 203 ms versus 444 ± 205 ms, p < 0.001). CONCLUSIONS: We found a decline in acetabular, femoral, and regional dGEMRIC indices for the surgically treated group at 1-year followup despite an improvement in all PROMs. We observed a similar but less pronounced decrease in the dGEMRIC index in symptomatic patients without surgical treatment indicating continuous cartilage degeneration. Although treatment of FAI is intended to alter the forces acting across the hip by eliminating impingement, its effects on cartilage biology are not clear. dGEMRIC provides a noninvasive method of assessing these effects. Longer term studies will be needed to determine whether the matrix changes of the bradytrophic cartilage seen here are permanent or clinically important. LEVEL OF EVIDENCE: Level II, therapeutic study.

What MRI Findings Predict Failure 10 Years After Surgery for Femoroacetabular Impingement?

BACKGROUND: Magnetic resonance arthrogram (MRA) with radial cuts is presently the best available preoperative imaging study to evaluate chondrolabral lesions in the setting of femoroacetabular impingement (FAI). Existing followup studies for surgical treatment of FAI have evaluated predictors of treatment failure based on preoperative clinical examination, intraoperative findings, and conventional radiography. However, to our knowledge, no study has examined whether any preoperative findings on MRA images might be associated with failure of surgical treatment of FAI in the long term. QUESTIONS/PURPOSES: The purposes of this study were (1) to identify the preoperative MRA findings that are associated with conversion to THA, any progression of osteoarthritis, and/or a Harris hip score of < 80 points after acetabuloplasty and/or osteochondroplasty of the femoral head-neck junction through a surgical hip dislocation (SHD) for FAI at a minimum 10-year followup; and (2) identify the age of patients with symptomatic FAI when these secondary degenerative findings were detected on preoperative radial MRAs. METHODS: We retrospectively studied 121 patients (146 hips) who underwent acetabuloplasty and/or osteochondroplasty of the femoral head-neck junction through SHD for symptomatic anterior FAI between July 2001 and March 2003. We excluded 35 patients (37 hips) with secondary FAI after previous surgery and 11 patients (12 hips) with Legg-Calvé-Perthes disease. All patients underwent preoperative MRA to further specify chondrolabral lesions except in 19 patients (32 hips) including 17 patients (20 hips) who presented with an MRI from an external institution taken with a different protocol, 10 patients with no preoperative MRA because the patients had already been operated on the contralateral side with a similar appearance, and two patients (two hips) refused MRA because of claustrophobia. This resulted in 56 patients (65 hips) with idiopathic FAI and a preoperative MRA. Of those, three patients (three hips) did not have minimal 10-year followup (one patient died; two hips with followup between 5 and 6 years). The remaining patients were evaluated clinically and radiographically at a mean followup of 11 years (range, 10-13 years). Thirteen pathologic radiographic findings on the preoperative MRA were evaluated for an association with the following endpoints using Cox regression analysis: conversion to THA, radiographic evidence of any progression of osteoarthritis, and/or a Harris hip score of < 80. The age of the patient when each degenerative pattern was found on the preoperative MRA was recorded. RESULTS: The following MRI findings were associated with one or more of our predefined failure endpoints: cartilage damage exceeding 60° of the circumference had a hazard ratio (HR) of 4.6 (95% confidence interval [CI], 3.6-5.6; p = 0.003) compared with a damage of less than 60°, presence of an acetabular rim cyst had a HR of 4.1 (95% CI, 3.1-5.2; p = 0.008) compared with hips without these cysts, and presence of a sabertooth osteophyte had a HR of 3.2 (95% CI, 2.3-4.2; p = 0.013) compared with hips without a sabertooth osteophyte. The degenerative pattern associated with the youngest patient age when detected on preoperative MRA was the sabertooth osteophyte (lower quartile 27 years) followed by cartilage damage exceeding 60° of the circumference (28 years) and the presence of an acetabular rim bone cyst (31 years). CONCLUSIONS: Preoperative MRAs with radial cuts reveal important findings that may be associated with future failure of surgical treatment for FAI. Most of these factors are not visible on conventional radiographs or standard hip MRIs. Preoperative MRA evaluation is therefore strongly recommended on a routine basis for patients undergoing these procedures. Findings associated with conversion to arthroplasty, radiographic evidence of any progression of osteoarthritis, and/or a Harris hip score of < 80 points should be incorporated into the decision-making process in patients being evaluated for joint-preserving hip surgery. LEVEL OF EVIDENCE: Level III, therapeutic study.

Acetabular Version Increases After Closure of the Triradiate Cartilage Complex.

BACKGROUND: Although the etiology of primary femoroacetabular impingement (FAI) is considered developmental, the underlying pathogenic mechanisms remain poorly understood. In particular, research identifying etiologic factors associated with pincer FAI is limited. Knowledge of the physiologic growth patterns of the acetabulum during skeletal maturation might allow conclusions on deviations from normal development that could contribute to pincer-related pathomorphologies. QUESTIONS/PURPOSES: In a population of healthy children, we asked if there were any differences related to skeletal maturation with regard to (1) acetabular version; (2) acetabular depth/width ratio; and (3) femoral head coverage in the same children as assessed by MRIs obtained 1 year apart. METHODS: We prospectively compared 129 MRIs in 65 asymptomatic volunteers without a known hip disorder from a mixed primary/high school population (mean age, 12.7 years; range, 7-16 years). All participants underwent two MRI examinations separated by a minimum interval of 1 year. Based on the status of the triradiate cartilage complex (open versus closed [TCC]), all hips were allocated to the following groups: "open-open" = open TCC at both MRIs (n = 45 hips [22 bilateral]); "open-closed" = open TCC at initial and closed TCC at followup MRI (n = 26 hips [13 bilateral]); and "closed-closed" group = closed TCC at both MRIs (n = 58 hips [29 bilateral]). We assessed acetabular version in the axial plane at five different locations (5, 10, 15, 20 mm below the acetabular dome and at the level of the femoral head) as well as three-dimensional (3-D) acetabular depth/width ratio and 3-D femoral head coverage on six radial MRI sequences oriented circumferentially around the femoral neck axis. Using analysis of variance for multigroup comparisons with Bonferroni adjustment for pairwise comparisons, we compared the results between the initial and followup MRI examinations and among the three groups. RESULTS: Acetabular version was increased in hips of the "open-closed" group at the followup MRI compared with the initial MRI at 5 mm (-6 ± 4.6 [95% confidence interval {CI}, -7.6 to -3.6] versus -1 ± 5.0 [95% CI, -3.3 to 0.7]; p < 0.001), 10 mm (0 ± 4.0 [95% CI, -1.6 to 2.1] versus 7 ± 4.6 [95% CI, 4.4-8.7]; p < 0.001), and 15 mm (8 ± 5.0 [95% CI, 6.1-10.2] versus 15 ± 4.6 [95% CI, 13.3-17.4]; p < 0.001) below the acetabular dome. Acetabular version did not change between the initial and followup MRI in the "open-open" and "closed-closed" groups. Independently of the groups, acetabular version was increased in all hips with a fused TCC compared with hips with an open TCC (mean difference measured at 5 mm below the acetabular dome at initial MRI examination: 2° ± 5.9° [95% CI, 0.2°-3.4°] versus -9° ± 4.4° [95% CI, -9.9° to -7.8°]; p < 0.001; at followup MRI examination: 1° ± 5.7° [95% CI, 0.1°-2.7°] versus -9° ± 3.8° [95% CI, -10° to -7.6°]; p < 0.001). Both acetabular depth/width ratio and femoral head coverage did not differ among the groups or between the initial and followup MRI examinations within each group. CONCLUSIONS: Although acetabular depth/width ratio and femoral head coverage remain relatively constant, acetabular version increases with advancing skeletal maturity. There seems to be a relatively narrow timeframe near physeal closure of the TCC within which acetabular orientation changes to more pronounced anteversion. Further studies with greater numbers and longer followup periods are required to support these findings and determine whether such version changes may contribute to pincer-type pathomorphologies. LEVEL OF EVIDENCE: Level II, prospective study.

Periacetabular Osteotomy Provides Higher Survivorship Than Rim Trimming for Acetabular Retroversion.

BACKGROUND: Acetabular retroversion can cause impaction-type femoroacetabular impingement leading to hip pain and osteoarthritis. It can be treated by anteverting periacetabular osteotomy (PAO) or acetabular rim trimming with refixation of the labrum. There is increasing evidence that acetabular retroversion is a rotational abnormality of the entire hemipelvis and not a focal overgrowth of the anterior acetabular wall, which favors an anteverting PAO. However, it is unknown if this larger procedure would be beneficial in terms of survivorship and Merle d'Aubigné scores in a midterm followup compared with rim trimming. QUESTIONS/PURPOSES: We asked if anteverting PAO results in increased survivorship of the hip compared with rim trimming through a surgical hip dislocation in patients with symptomatic acetabular retroversion. METHODS: We performed a retrospective, comparative study evaluating the midterm survivorship of two matched patient groups with symptomatic acetabular retroversion undergoing either anteverting PAO or acetabular rim trimming through a surgical hip dislocation. Acetabular retroversion was defined by a concomitantly present positive crossover, posterior wall, and ischial spine sign. A total of 279 hips underwent a surgical intervention for acetabular retroversion at our center between 1997 and 2012 (166 periacetabular osteotomies, 113 rim trimmings through surgical hip dislocation). A total of 99 patients (60%) were excluded from the PAO group and 56 patients (50%) from the rim trimming group because they had any of several prespecified conditions (eg, dysplasia or pediatric conditions 61 [37%] for the PAO group and two [2%] for the rim trimming group), matching (10 [6%]/10 [9%] hips), deficient records (10 [6%]/13 [12%] hips), or the patient declined or was lost to followup (18 [11%]/31 [27%] hips). This left 67 hips (57 patients) that underwent anteverting PAO and 57 hips (52 patients) that had acetabular rim trimming. The two groups did not differ in terms of age, sex, body mass index, preoperative ROM, preoperative Merle d'Aubigné-Postel score, radiographic morphology of the acetabulum (except total and anterior acetabular coverage), alpha angle, Tönnis grade of osteoarthritis, and labral and chondral lesions on the preoperative MRI. During the period in question, we generally performed PAO from 1997 to 2003. With the availability of surgical hip dislocation and labral refixation, we generally performed rim trimming from 2004 to 2010. With growing knowledge of the underlying pathomorphology, anteverting PAOs became more common again around 2007 to 2008. A minimum followup of 2 years was required for this study. Failures were included at any time. The median followup for the anteverting PAO group was 9.5 years (range, 2-17.4 years) and 6.8 years (range, 2.2-10.5 years) for the rim trimming group (p < 0.001). Kaplan-Meier survivorship analysis was performed using the following endpoints at 5 and 10 years: THA, radiographic progression of osteoarthritis by one Tönnis grade, and/or Merle d'Aubigné-Postel score < 15 points. RESULTS: Although the 5-year survivorship of the two groups was not different with the numbers available (86% [95% confidence interval {CI}, 76%-94%] for anteverting PAO versus 86% [95% CI, 76%-96%] for acetabular rim trimming), we found increased survivorship at 10 years in hips undergoing anteverting PAO for acetabular retroversion (79% [95% CI, 68%-90%]) compared with acetabular rim trimming (23% [95% CI, 6%-40%]) at 10 years (p < 0.001). The drop in the survivorship curve for the acetabular rim trimming through surgical hip dislocation group started at Year 6. The main reason for failure was a decreased Merle d'Aubigné score. CONCLUSIONS: Anteverting PAO may be the more appropriate treatment for hips with substantial acetabular retroversion. This may be the result of reduction of an already smaller lunate surface of hips with acetabular retroversion through rim trimming. However, rim trimming may still benefit hips with acetabular retroversion in which only one or two of the three signs are positive. Future randomized studies should compare these treatments. LEVEL OF EVIDENCE: Level III, therapeutic study.

Hips With Protrusio Acetabuli Are at Increased Risk for Failure After Femoroacetabular Impingement Surgery: A 10-year Followup.

BACKGROUND: Protrusio acetabuli is a rare anatomic pattern of the hip in which the femoral head protrudes into the true pelvis. The increased depth of the hip and the excessive size of the lunate surface typically lead to severe pincer-type femoroacetabular impingement (FAI); however, to our knowledge, there are no published mid- or long-term studies on results of circumferential acetabular rim trimming through a surgical hip dislocation for patients with this condition. QUESTIONS/PURPOSES: (1) What is the 10-year survivorship of the hips treated with circumferential rim trimming through a surgical hip dislocation compared with a control group of hips that underwent surgery for pincer FAI but that did not have protrusio acetabuli? (2) What are the factors that were associated with a decreased likelihood of survivorship in those hips with the following endpoints: total hip arthroplasty, Merle d'Aubigné score of less than 15, and/or radiographic progression of osteoarthritis (OA)? (3) Does the radiographic pattern of degeneration differ between the two groups? METHODS: We performed a case-control study comparing two groups: a protrusio group (32 patients [39 hips]) and a control group (66 patients [86 hips]). The control group consisted of hips treated with a surgical hip dislocation for pincer FAI and did not include hips with a positive protrusio sign or a lateral center-edge angle > 39°. The study group did not differ from the control group regarding the preoperative Tönnis OA score, age, and body mass index. However, the study group had more women, decreased mean height and weight, and lower preoperative Merle d'Aubigné-Postel scores, which were inherent differences at the time of first presentation. During the period in question, the indication for performing these procedures was a painfully restricted range of motion in flexion and internal rotation (positive impingement sign). The mean followup of the protrusio group (9 ± 5 years [range, 2-18 years]) did not differ from the control group (11 ± 1 years [range, 10-13 years], p = 0.109). At the respective minimum followup intervals in the underlying database from which cases and control subjects were drawn, followup was 100% for patients with protrusion who underwent FAI surgery and 97% for patients with FAI who underwent surgery for other anatomic patterns (three of 86 hips). We assessed the Merle d'Aubigné-Postel score, Harris hip score, WOMAC, and UCLA activity score at latest followup. A Kaplan-Meier survivorship analysis of the hip was calculated if any of the following endpoints for both groups occurred: conversion to total hip arthroplasty, a Merle d'Aubigné-Postel score < 15, and/or radiographic progression of OA. Differences in survivorship were analyzed using the log-rank test. RESULTS: At 10-year followup, we found a decreased survivorship of the hip for the protrusio group (51% [95% confidence interval {CI}, 34%-67%]) compared with the control group (83% [95% CI, 75%-91%], p < 0.001) with one or more of the endpoints stated. We found four multivariate factors associated with a decreased likelihood of survival of the native hip according to the mentioned endpoints: body mass index > 25 kg/m(2) (adjusted hazard ratio, 6.4; 95% CI, 5.2-8.1; p = 0.009), a preoperative Tönnis OA score ≥ 1 (13.3; 95% CI, 11.8-14.9; p = 0.001), a postoperative lateral center-edge angle > 40° (4.2; 95% CI, 2.8-5.6; p = 0.042), and a postoperative posterior coverage > 56% (6.0; 95% CI, 4.3-7.6; p = 0.037). Preoperatively, joint space narrowing and osteophytes were more frequent posteroinferior (joint space narrowing 18% versus 2%, p = 0.008; osteophytes 21% versus 4%, p = 0.007), medial (joint space narrowing 33% versus 5%, p < 0.001) and  anterior (osteophytes 15% versus 1%, p = 0.004) in the protrusio compared with the control group. After correction in hips with protrusio, progression of joint space narrowing (from 6% to 45%, p = 0.001) and osteophyte formation (from 15% to 52%, p = 0.002) was most pronounced laterally. CONCLUSIONS: At 10 years, in 51% of all hips undergoing open acetabular rim trimming for protrusio acetabuli, the hip can be preserved without further radiographic degeneration and a Merle d'Aubigné score > 15. Even with the lack of a control group with nonoperative treatment, isolated rim trimming may not entirely resolve the pathomorphology in protrusio hips given the clearly inferior results compared with surgical hip dislocation for FAI without severe overcoverage. LEVEL OF EVIDENCE: Level III, therapeutic study.

What are the radiographic reference values for acetabular under- and overcoverage?

BACKGROUND: Both acetabular undercoverage (hip dysplasia) and overcoverage (pincer-type femoroacetabular impingement) can result in hip osteoarthritis. In contrast to undercoverage, there is a lack of information on radiographic reference values for excessive acetabular coverage. QUESTIONS/PURPOSES: (1) How do common radiographic hip parameters differ in hips with a deficient or an excessive acetabulum in relation to a control group; and (2) what are the reference values determined from these data for acetabular under- and overcoverage? METHODS: We retrospectively compared 11 radiographic parameters describing the radiographic acetabular anatomy among hip dysplasia (26 hips undergoing periacetabular osteotomy), control hips (21 hips, requiring no rim trimming during surgical hip dislocation), hips with overcoverage (14 hips, requiring rim trimming during surgical hip dislocation), and hips with severe overcoverage (25 hips, defined as having acetabular protrusio). The hips were selected from a patient cohort of a total of 593 hips. Radiographic parameters were assessed with computerized methods on anteroposterior pelvic radiographs and corrected for neutral pelvic orientation with the help of a true lateral radiograph. RESULTS: All parameters except the crossover sign differed among the four study groups. From dysplasia through control and overcoverage, the lateral center-edge angle, acetabular arc, and anteroposterior/craniocaudal coverage increased. In contrast, the medial center-edge angle, extrusion/acetabular index, Sharp angle, and prevalence of the posterior wall sign decreased. The following reference values were found: lateral center-edge angle 23° to 33°, medial center-edge angle 35° to 44°, acetabular arc 61° to 65°, extrusion index 17% to 27%, acetabular index 3° to 13°, Sharp angle 38° to 42°, negative crossover sign, positive posterior wall sign, anterior femoral head coverage 15% to 26%, posterior femoral head coverage 36% to 47%, and craniocaudal coverage 70% to 83%. CONCLUSIONS: These acetabular reference values define excessive and deficient coverage. They may be used for radiographic evaluation of symptomatic hips, may offer possible predictors for surgical outcomes, and serve to guide clinical decision-making.

Twelve percent of hips with a primary cam deformity exhibit a slip-like morphology resembling sequelae of slipped capital femoral epiphysis.

BACKGROUND: In some hips with cam-type femoroacetabular impingement (FAI), we observed a morphology resembling a more subtle form of slipped capital femoral epiphysis (SCFE). Theoretically, the morphology in these hips should differ from hips with a primary cam-type deformity. QUESTIONS/PURPOSES: We asked if (1) head-neck offset; (2) epiphyseal angle; and (3) tilt angle differ among hips with a slip-like morphology, idiopathic cam, hips after in situ pinning of SCFE, and normal hips; and (4) what is the prevalence of a slip-like morphology among cam-type hips? METHODS: We retrospectively compared the three-dimensional anatomy of hips with a slip-like morphology (29 hips), in situ pinning for SCFE (eight hips), idiopathic cam deformity (171 hips), and 30 normal hips using radial MRI arthrography. Normal hips were derived from 17 asymptomatic volunteers. All other hips were recruited from a series of 277 hips (243 patients) seen at a specialized academic hip center between 2006 and 2010. Forty-one hips with isolated pincer deformity were excluded. Thirty-six of 236 hips had a known cause of cam impingement (secondary cam), including eight hips after in situ pinning of SCFE (postslip group). The 200 hips with a primary cam were separated in hips with a slip-like morphology (combination of positive fovea sign [if the neck axis did not intersect with the fovea capitis] and a tilt angle [between the neck axis and perpendicular to the basis of the epiphysis] exceeding 4°) and hips with an idiopathic cam. We evaluated offset ratio, epiphyseal angle (angle between the neck axis and line connecting the center of the femoral head and the point where the physis meets the articular surface), and tilt angle circumferentially around the femoral head-neck axis. Prevalence of slip-like morphology was determined based on the total of 236 hips with cam deformities. RESULTS: Offset ratio was decreased anterosuperiorly in idiopathic cam, slip-like, and postslip (eg, 1 o'clock position with a mean offset ranging from 0.00 to 0.14; p < 0.001 for all groups) compared with normal hips (0.25 ± 0.06 [95% confidence interval, 0.13-0.37]) and increased posteroinferiorly in slip-like (eg, 8 o'clock position, 0.5 ± 0.09 [0.32-0.68]; p < 0.001) and postslip groups (0.55 ± 0.12 [0.32-0.78]; p < 0.001) and did not differ in idiopathic cam (0.32 ± 0.09 [0.15-0.49]; p = 0.323) compared with normal (0.31 ± 0.07 [0.18-0.44]) groups. Epiphyseal angle was increased anterosuperiorly in the slip-like (eg, 1 o'clock position, 70° ± 9° [51°-88°]; p < 0.001) and postslip groups (75° ± 13° [49°-100°]; p = 0.008) and decreased in idiopathic cam (50° ± 8° [35°-65°]; p < 0.001) compared with normal hips (58° ± 8° [43°-74°]). Posteroinferiorly, epiphyseal angle was decreased in slip-like (eg, 8 o'clock position, 54° ± 10° [34°-74°]; p < 0.001) and postslip (44° ± 11° [23°-65°]; p < 0.001) groups and did not differ in idiopathic cam (76° ± 8° [61°-91°]; p = 0.099) compared with normal (73° ± 7° [59°-88°]) groups. Tilt angle increased in slip-like (eg, 2/8 o'clock position, 14° ± 8° [-1° to 30°]; p < 0.001) and postslip hips (29° ± 10° [9°-48°]; p < 0.001) and decreased in hips with idiopathic cam (-7° ± 5° [-17° to 4°]; p < 0.001) compared with normal (-1° ± 5° [-10° to 8°]) hips. The prevalence of a slip-like morphology was 12%. CONCLUSIONS: The slip-like morphology is the second most frequent pathomorphology in hips with primary cam deformity. MRI arthrography of the hip allows identifying a slip-like morphology, which resembles hips after in situ pinning of SCFE and distinctly differs from hips with idiopathic cam. These results support previous studies reporting that SCFE might be a risk factor for cam-type FAI.

Rotational femoral osteotomies and cam resection improve hip function and internal rotation for patients with anterior hip impingement and decreased femoral version.

Femoroacetabular impingement (FAI) patients with reduced femoral version (FV) are poorly understood. The aim of this study is to assess (i) hip pain and range of motion, (ii) subjective satisfaction and (iii) subsequent surgeries of symptomatic patients who underwent rotational femoral osteotomies. A retrospective case series involving 18 patients (23 hips, 2014-2018) with anterior hip pain that underwent rotational femoral osteotomies for treatment of decreased FV was performed. The mean preoperative age was 25 ± 6 years (57% male), and all patients had decreased FV < 10° and minimum 1-year follow-up (mean follow-up 2 ± 1 years). Surgical indication was the positive anterior impingement test, limited internal rotation (IR) in 90° of flexion (mean 10 ± 8°) and IR in extension (mean 24 ± 11°), anterosuperior chondrolabral damage in Magnet resonance (MR) arthrography, CT-based measurement of decreased FV (mean 5 ± 3°, Murphy method) and no osteoarthritis (Tönnis Grade 0). Most patients had intra- and extra-articular subspine FAI (patient-specific 3D impingement simulation). Subtrochanteric rotational femoral osteotomies to increase FV (correction 20 ± 4°) were combined with cam resection (78%) and surgical hip dislocation (91%). (i) The positive anterior impingement test decreased significantly (P < 0.001) from pre- to postoperatively (100% to 9%). IR in 90° of flexion increased significantly (P < 0.001, 10 ± 8° to 31 ± 10°). (ii) Subjective satisfaction increased significantly (P < 0.001) from pre- to postoperatively (33% 77%). The mean Merle d'Aubigné and Postel score increased significantly (P < 0.001) from 14 ± 2 (8-15) points to 17 ± 1 (13-18, P < 0.001) points. Most patients (85%) reported at follow-up that they would undergo surgery again. (iii) At follow-up, all 23 hips were preserved (no conversion to total hip arthroplasty). One hip (4%) underwent revision osteosynthesis. Proximal rotational femoral osteotomies combined with cam resection improve hip pain and IR in most FAI patients with decreased FV at short-term follow-up. Rotational femoral osteotomies to increase FV are safe and effective.

MR-based Bony 3D models enable radiation-free preoperative patient-specific analysis and 3D printing for SCFE patients.

Objectives: Slipped capital femoral epiphyses (SCFE) is a common pediatric hip disease with the risk of osteoarthritis and impingement deformities, and 3D models could be useful for patient-specific analysis. Therefore, magnetic resonance imaging (MRI) bone segmentation and feasibility of 3D printing and of 3D ROM simulation using MRI-based 3D models were investigated. Methods: A retrospective study involving 22 symptomatic patients (22 hips) with SCFE was performed. All patients underwent preoperative hip MR with pelvic coronal high-resolution images (T1 images). Slice thickness was 0.8-1.2 mm. Mean age was 12 ± 2 years (59% male patients). All patients underwent surgical treatment. Semi-automatic MRI-based bone segmentation with manual corrections and 3D printing of plastic 3D models was performed. Virtual 3D models were tested for computer-assisted 3D ROM simulation of patients with knee images and were compared to asymptomatic contralateral hips with unilateral SCFE (15 hips, control group). Results: MRI-based bone segmentation was feasible (all patients, 100%, in 4.5 h, mean 272 ± 52 min). Three-dimensional printing of plastic 3D models was feasible (all patients, 100%) and was considered helpful for deformity analysis by the treating surgeons for severe and moderate SCFE. Three-dimensional ROM simulation showed significantly (p < 0.001) decreased flexion (48 ± 40°) and IR in 90° of flexion (-14 ± 21°, IRF-90°) for severe SCFE patients with MRI compared to control group (122 ± 9° and 36 ± 11°). Slip angle improved significantly (p < 0.001) from preoperative 54 ± 15° to postoperative 4 ± 2°. Conclusion: MRI-based 3D models were feasible for SCFE patients. Three-dimensional models could be useful for severe SCFE patients for preoperative 3D printing and deformity analysis and for ROM simulation. This could aid for patient-specific diagnosis, treatment decisions, and preoperative planning. MRI-based 3D models are radiation-free and could be used instead of CT-based 3D models in the future.

Composition and micromechanical properties of the femoral neck compact bone in relation to patient age, sex and hip fracture occurrence.

Current clinical methods of bone health assessment depend to a great extent on bone mineral density (BMD) measurements. However, these methods only act as a proxy for bone strength and are often only carried out after the fracture occurs. Besides BMD, composition and tissue-level mechanical properties are expected to affect the whole bone's strength and toughness. While the elastic properties of the bone extracellular matrix (ECM) have been extensively investigated over the past two decades, there is still limited knowledge of the yield properties and their relationship to composition and architecture. In the present study, morphological, compositional and micropillar compression bone data was collected from patients who underwent hip arthroplasty. Femoral neck samples from 42 patients were collected together with anonymous clinical information about age, sex and primary diagnosis (coxarthrosis or hip fracture). The femoral neck cortex from the inferomedial region was analyzed in a site-matched manner using a combination of micromechanical testing (nanoindentation, micropillar compression) together with micro-CT and quantitative polarized Raman spectroscopy for both morphological and compositional characterization. Mechanical properties, as well as the sample-level mineral density, were constant over age. Only compositional properties demonstrate weak dependence on patient age: decreasing mineral to matrix ratio (p = 0.02, R2 = 0.13, 2.6 % per decade) and increasing amide I sub-peak ratio I∼1660/I∼1683 (p = 0.04, R2 = 0.11, 1.5 % per decade). The patient's sex and diagnosis did not seem to influence investigated bone properties. A clear zonal dependence between interstitial and osteonal cortical zones was observed for compositional and elastic bone properties (p < 0.0001). Site-matched microscale analysis confirmed that all investigated mechanical properties except yield strain demonstrate a positive correlation with the mineral fraction of bone. The output database is the first to integrate the experimentally assessed microscale yield properties, local tissue composition and morphology with the available patient clinical information. The final dataset was used for bone fracture risk prediction in-silico through the principal component analysis and the Naïve Bayes classification algorithm. The analysis showed that the mineral to matrix ratio, indentation hardness and micropillar yield stress are the most relevant parameters for bone fracture risk prediction at 70 % model accuracy (0.71 AUC). Due to the low number of samples, further studies to build a universal fracture prediction algorithm are anticipated with the higher number of patients (N > 200). The proposed classification algorithm together with the output dataset of bone tissue properties can be used for the future comparison of existing methods to evaluate bone quality as well as to form a better understanding of the mechanisms through which bone tissue is affected by aging or disease.

Assessment of femoral retroversion on preoperative hip magnetic resonance imaging in patients with slipped capital femoral epiphysis: Theoretical implications for hip impingement risk estimation.

Purpose: Slipped capital femoral epiphysis is a common pediatric hip disease and was associated with femoral retroversion, but femoral version was rarely measured. Therefore, mean femoral version, mean femoral neck version, and prevalence of femoral retroversion were analyzed for slipped capital femoral epiphysis patients. Methods: A retrospective observational study evaluating preoperative hip magnetic resonance imaging of 27 patients (49 hips) was performed. Twenty-seven untreated slipped capital femoral epiphysis patients (28 slipped capital femoral epiphysis hips and 21 contralateral hips, age 10-16 years) were evaluated (79% stable slipped capital femoral epiphysis, 22 patients; 43% severe slipped capital femoral epiphysis, 12 patients). Femoral version was measured using Murphy method on magnetic resonance imaging (January 2014-December 2021, rapid bilateral 3-dimensional T1 water-only Dixon-based images of pelvis and knee). All slipped capital femoral epiphysis patients underwent surgery after magnetic resonance imaging. Results: Mean femoral version of slipped capital femoral epiphysis patients (-1° ± 15°) was significantly (p < 0.001) lower compared to contralateral side (15° ± 14°). Femoral version of slipped capital femoral epiphysis patients had significantly (p < 0.001) wider range from -42° to 35° (range 77°) compared to contralateral side (-5° to 44°, range 49°). Mean femoral neck version of slipped capital femoral epiphysis patients (6° ± 15°) was lower compared to contralateral side (11° ± 12°). Fifteen slipped capital femoral epiphysis patients (54%) had absolute femoral retroversion (femoral version < 0°). Six of the 12 hips (50%) with severe slips and 4 of the 8 hips (50%) with mild slips had absolute femoral retroversion (femoral version < 0°). Ten slipped capital femoral epiphysis patients (40%) had absolute femoral neck retroversion (femoral neck version < 0°). Conclusion: Although slipped capital femoral epiphysis patients showed asymmetrically lower femoral version compared to contralateral side, there was a wide range of femoral version, underlining the importance of patient-specific femoral version analysis on preoperative magnetic resonance imaging. Absolute femoral retroversion was prevalent in half of slipped capital femoral epiphysis patients, in half of severe slipped capital femoral epiphysis patients, and in half of mild slipped capital femoral epiphysis patients. This has implications for anterior hip impingement and for surgical treatment with in situ pinning or femoral osteotomy (e.g. proximal femoral derotation osteotomy) or other hip preservation surgery.

Does the dGEMRIC Index Recover 3 Years After Surgical FAI Correction and an Initial dGEMRIC Decrease at 1-Year Follow-up? A Controlled Prospective Study.

BACKGROUND: Delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC) allows objective and noninvasive assessment of cartilage quality. An interim analysis 1 year after correction of femoroacetabular impingement (FAI) previously showed that the dGEMRIC index decreased despite good clinical outcome. PURPOSE: To evaluate dGEMRIC indices longitudinally in patients who underwent FAI correction and in a control group undergoing nonoperative treatment for FAI. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: This prospective, comparative longitudinal study included 39 patients (40 hips) who received either operative (n = 20 hips) or nonoperative (n = 20 hips) treatment. Baseline demographic characteristics and presence of osseous deformities did not differ between groups. All patients received indirect magnetic resonance arthrography at 3 time points (baseline, 1 and 3 years of follow-up). The 3-dimensional cartilage models were created using a custom-developed deep learning-based software. The dGEMRIC indices were determined separately for acetabular and femoral cartilage. A mixed-effects model was used for statistical analysis in repeated measures. RESULTS: The operative group showed an initial (preoperative to 1-year follow-up) decrease of dGEMRIC indices: acetabular from 512 ± 174 to 392 ± 123 ms and femoral from 530 ± 173 to 411 ± 117 ms (both P < .001). From 1-year to 3-year follow-up, dGEMRIC indices improved again: acetabular from 392 ± 123 to 456 ± 163 ms and femoral from 411 ± 117 to 477 ± 169 ms (both P < .001). The nonoperative group showed no significant changes in dGEMRIC indices in acetabular and femoral cartilage from baseline to either follow-up point (all P > .05). CONCLUSION: This study showed that 3 years after FAI correction, the dGEMRIC indices improved compared with short-term 1-year follow-up. This may be due to normalized joint biomechanics or regressive postoperative activation of the inflammatory cascade after intra-articular surgery.

LCPD: reduced range of motion resulting from extra- and intraarticular impingement.

BACKGROUND: Legg-Calvé-Perthes disease (LCPD) often results in a deformity that can be considered as a complex form of femoroacetabular impingement (FAI). Improved preoperative characterization of the FAI problem based on a noninvasive three-dimensional computer analysis may help to plan the appropriate operative treatment. QUESTIONS/PURPOSES: We asked whether the location of impingement zones, the presence of additional extraarticular impingement, and the resulting ROM differ between hips with LCPD and normal hips or hips with FAI. METHODS: We used a CT-based virtual dynamic motion analysis based on a motion algorithm to simulate the individual motion for 13 hips with LCPD, 22 hips with FAI, and 27 normal hips. We then determined the motion and impingement pattern of each hip for the anterior (flexion, adduction, internal rotation) and the posterior impingement tests (extension, adduction, external rotation). RESULTS: The location of impingement zones in hips with LCPD differed compared with the FAI/normal groups. Intra- and extraarticular impingement was more frequent in LCPD (79% and 86%, respectively) compared with normal (15%, 15%) and FAI hips (36%, 14%). Hips with LCPD had decreased amplitude for all hip motions (flexion, extension, abduction, adduction, internal and external rotation) compared with FAI or normal. CONCLUSIONS: Hips with LCPD show a decreased ROM as a result of a higher prevalence of intra- and extraarticular FAI. Noninvasive assessment of impingement characteristics in hips with LCPD may be helpful in the future for establishment of a surgical plan.

Combined abnormalities of femoral version and acetabular version and McKibbin Index in FAI patients evaluated for hip preservation surgery.

Frequencies of combined abnormalities of femoral version (FV) and acetabular version (AV) and of abnormalities of the McKibbin index are unknown. To investigate the prevalence of combined abnormalities of FV and AV and of abnormalities of the McKibbin index in symptomatic patients with femoroacetabular impingement (FAI), a retrospective, Institutional Review Board (IRB)-approved study of 333 symptomatic patients (384 hips) that were presented with hip pain and FAI was performed. The computed tomography/magnetic resonance imaging based measurement of central AV, cranial AV and FV was compared among five subgroups with distinguished FAI subgroups and patients that underwent a hip preservation surgery. The allocation to each subgroup was based on AP radiographs. Normal AV and FV were 10-25°. The McKibbin index is the sum of central AV and FV. Of patients that underwent a hip preservation surgery, 73% had a normal McKibbin index (20-50°) but 27% had an abnormal McKibbin index. Of all patients, 72% had a normal McKibbin index, but 28% had abnormal McKibbin index. The prevalence of combined abnormalities of FV and AV varied among subgroups: a higher prevalence of decreased central AV combined with decreased FV of patients with acetabular-retroversion group (12%) and overcoverage (11%) was found compared with mixed-type FAI (5%). Normal AV combined with normal FV was present in 41% of patients with cam-type FAI and in 34% of patients with overcoverage. Patients that underwent a hip preservation surgery had normal mean FV (17 ± 11°), central AV (19 ± 7°), cranial AV (16 ± 10°) and McKibbin index (36 ± 14°). Frequency of combined abnormalities of AV and FV differs between subgroups of FAI patients. Aggravated and compensated McKibbin index was prevalent in FAI patients. This has implications for open hip preservation surgery (surgical hip dislocation or femoral derotation osteotomy) or hip arthroscopy or non-operative treatment.