Contralateral slip after unilateral slipped capital femoral epiphysis is associated with acetabular retroversion but not increased acetabular depth and overcoverage

Fix it or risk it? Revisiting contralateral hip prophylactic fixation in unilateral slipped capital femoral epiphysis: an updated review of the past decade's literature

Slipped capital femoral epiphysis (SCFE) is a common hip pathology occurring in pediatrics and adolescents, and its management is well documented in the literature regardless of its severity. In patients presenting with unilateral SCFE, the incidence of subsequent contralateral slip (SCS) is variable among studies, and the issue of contralateral hip prophylactic fixation (CHPF) becomes a concern. The fundamental rationale behind performing CHPF is to avoid the subsequent contralateral slip, which consequently lowers the risk of femoral head avascular necrosis and chondrolysis. However, prophylactic fixation carries the risk of altering proximal femoral growth, peri-implant fractures, and requiring secondary surgery for hardware removal. The current review was formulated based on the literature published in the last decade and aimed to evaluate the incidence of SCS and indications for CHPF. Apart from institutions' protocol or individual surgeons' preferences, various variables were suggested to justify CHPF, including patient-related variables such as the presence of endocrinopathy, those younger than 13 years old (10-13), and patients with mOBAS ≤ 20. Radiological parameters, posterior slip angle ≥ 14.5°, positive crossover sign, posterior epiphyseal tilt of ≥ 10°, alpha angle of ≥ 49°, and a Probability analysis of sequential SCFE (PASS score) of ≥ 3. However, there is still a controversy in the literature regarding CHPF performance and which parameter is highly dependable for predicting the SCS. The controversy extends to the effect and efficacy of various fixation hardware and whether keeping patients under observation is less effective than CHPF. Furthermore, well-designed randomized controlled trials are lacking, and their performance is warranted to establish clear indications for performing CHPF and to clarify its safety, possible consequences, and cost-effectiveness.

Novelties in slipped capital femoral epiphysis imaging: A narrative review

Rationale and objectives

Imaging plays a key role in Slipped Capital Femoral Epiphysis diagnosis and severity assessment. In the last two decades, signs and measurements emerged in literature showed potential to help in SCFE diagnosis and tailoring treatment. The purpose of this review is to collect and discuss new imaging signs, measurements, and techniques according to investigations published after 2000 to improve SCFE diagnosis.

Material and methods

The PubMed, Scopus, and Science Direct databases were used to search for relevant articles related to imaging in SCFE diagnosis from January 2000 to March 2023. Article selection and review was performed by two board-certified radiologists). Article quality assessment were conducted by authors using QUADAS-2 and SANRA evaluation tools.

Results

The research resulted in a total of 2577 articles. After duplicates removal and abstract analysis, 28 articles were finally selected for full-text analysis. Seventeen articles were focused on Radiographs, 6 on CT, 1 on both Radiographs and CT, 4 on MRI. No study focused on ultrasound was selected.

Conclusions

Use of modified Klein's line and S-sign may improve radiographs accuracy in daily routine. Lucency sign may help in early diagnosis on radiographs. Preoperative CT may be useful in planning a tailored treatment predicting SCFE severity and instability. MRI is the most accurate modality to diagnose SCFE at early stage. Nevertheless, it cannot be used to predict the risk of contralateral SCFE. Risk prediction can be assessed with radiographs, using a new rapid mOBS. Further investigation and validation of these sign is needed.

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.

Prophylactic fixation of the unaffected contralateral side in children with slipped capital femoral epiphysis seems favorable: A systematic review

BACKGROUND

Slipped capital femoral epiphysis (SCFE) occurs in adolescents and has an incidence of around 10 per 100000 children. Children presenting with a unilateral SCFE are 2335 times more likely to develop a contralateral SCFE than the general population. Prognostic factors that have been suggested to increase the risk of contralateral slip include a younger patient, an underlying endocrine disorder, growth hormone use and a higher radiographic posterior sloping angle. However, there is still much debate on the advantages and disadvantages of prophylactic fixation of the unaffected side in an otherwise healthy patient.

AIM

To investigate the risk rate of contralateral SCFE and assess the (dis)advantages of prophylactic fixation of the contralateral hip.

METHODS

A systematic literature search was performed in the Embase, Medline, Web of Science Core Collection and Cochrane databases. Search terms included 'slipped capital femoral epiphysis,' 'fixation,' 'contralateral,' and derivatives. The eligibility of the acquired articles was independently assessed by the authors and additional relevant articles were included through cross-referencing. Publications were considered eligible for inclusion if they presented data about otherwise healthy children with primarily unilateral SCFE and the outcomes of prophylactically pinning their unaffected side, or about the rates of contralateral slips and complications thereof. The study quality of the included articles was assessed independently by the authors by means of the methodological index for non-randomized studies criteria.

RESULTS

Of 293 identified unique publications, we included 26 studies with a total of 12897 patients. 1762 patients (14%) developed a subsequent symptomatic contralateral slip. In addition, 38% of patients developed a subsequent slip on the contralateral side without experiencing clinical symptoms. The most outspoken advantage of prophylactic fixation of the contralateral hip in the literature is prevention of an (asymptomatic) slip, thus reducing the increased risk of avascular necrosis (AVN), cam morphology and osteoarthritis. Disadvantages include an increased risk of infection, AVN, peri-implant fractures, loss of fixation as well as migration of hardware and morphologic changes as a consequence of growth guidance. These risks, however, appeared to only occur incidentally and were usually mild compared to the risks involved with an actual SCFE.

CONCLUSION

The advantages of prophylactic pinning of the unaffected side in otherwise healthy patients with unilateral SCFE seem to outweigh the disadvantages. The final decision for treatment remains to be patient-tailored.

Acetabular retroversion is prevalent and proportional to the severity of slipped upper femoral epiphysis

Aims

Slipped upper femoral epiphysis (SUFE) has well documented biochemical and mechanical risk factors. Femoral and acetabular morphologies seem to be equally important. Acetabular retroversion has a low prevalence in asymptomatic adults. Hips with dysplasia, osteoarthritis, and Perthes’ disease, however, have higher rates, ranging from 18% to 48%. The aim of our study was to assess the prevalence of acetabular retroversion in patients presenting with SUFE using both validated radiological signs and tomographical measurements.

Methods

A retrospective review of all SUFE surgical cases presenting to the Royal Children’s Hospital, Melbourne, Australia, from 2012 to 2019 were evaluated. Preoperative plain radiographs were assessed for slip angle, validated radiological signs of retroversion, and standardized postoperative CT scans were used to assess cranial and mid-acetabular version.

Results

In all, 116 SUFEs presented in 107 patients who underwent surgical intervention; 47 (52%) were male, with a mean age of 12.7 years (7.5 to 16.6). Complete radiological data was available for 91 patients (99 hips) with adequate axial CT imaging of both hips. Overall, 82 patients (82%) underwent pinning in situ (PIS), with subcapital realignment surgery (SRS) performed in 17 patients (18%) (slip angles > 75°). Contralateral prophylactic PIS was performed in 72 patients (87%). On the slip side, 62 patients (68%) had one or more radiological sign of retroversion. Tomographical acetabular retroversion was more pronounced cranially than caudally of the acetabulum on both the affected side and the contralateral side (p < 0.001) as expected in the normal population. Increasing severity of the slip was found to be directly proportional to the degree of reduction in cranial and central acetabular version (p < 0.05) in the SUFE hips.

Conclusion

Acetabular retroversion is more prevalent in patients with SUFE than previously reported, and have been shown be correlated to the severity of the slip presentation. The presence of radiological signs of acetabular retroversion could be used to justify prophylactic contralateral pinning.

Cite this article: Bone Jt Open 2022;3(2):158–164.

Diagnosis of acetabular retroversion: Three signs positive and increased retroversion index have higher specificity and higher diagnostic accuracy compared to isolated positive cross over sign

Objectives

The crossover-sign (COS) is a radiographic sign for diagnosis of acetabular-retroversion(AR) in patients with femoroacetabular-impingement (FAI) but overestimates AR. Three signs combined with retroversion-index (RI) could potentially improve diagnostic-accuracy.

Aims

(1)

To calculate central acetabular-version (AV, CT/MRI) in patients with isolated positive COS and in patients with three radiographic signs for AR on radiographs (AP).

(2)

To calculate diagnostic performance of positive COS and of three signs combined with retroversion-index (RI) > 30% on radiographs (AP) to detect global AR (AV < 10°, CT/MRI).

Methods

A retrospective, IRB-approved, controlled diagnostic study comparing radiographic signs for AR (AP radiographs) with MRI/CT-based measurement of central AV was performed. 462 symptomatic patients (538 hips) with FAI or hip-dysplasia were compared to control-group (48 hips). Three signs for AR(on radiographs) were analyzed: COS, posterior-wall-sign and ischial-spine-sign. RI (synonym cross-over-index) quantifies overlap of anterior and posterior wall in case of positive COS. Diagnostic performance for COS and for three signs combined with RI > 30% to detect central AV < 10° (global AR) was calculated.

Results

(1)

Central AV was significantly (p < 0.001) decreased (13 ± 6°, CT/MRI) in patients with three signs for AR and RI > 30% on radiographs compared to patients with positive COS (18 ± 7°).

(2)

Sensitivity and specificity of three signs combined with RI > 30% on radiographs was 85% and 63% (87% and 23% for COS). Negative-predictive-value (NPV) was 94% (93% for COS) to rule out global AR (AV < 10°, CT/MRI). Diagnostic accuracy increased significantly (p < 0.001) from 31% (COS) to 68% using three signs.

Conclusion

Improved specificity and diagnostic accuracy for diagnosis of global AR can help to avoid misdiagnosis. Global AR can be ruled out with a probability of 94% (NPV) in the absence of three radiographic signs combined with retroversion-index < 30% (e.g. isolated COS positive).