Is Assessment of Femoral Head Perfusion During Modified Dunn for Unstable Slipped Capital Femoral Epiphysis an Accurate Indicator of Osteonecrosis?

Intraoperative Epiphyseal Perfusion Monitoring Does Not Reliably Predict Osteonecrosis Following Treatment of Unstable SCFE

BACKGROUND

Avascular necrosis (AVN) remains the most dreaded complication of unstable slipped capital femoral epiphysis (SCFE) treatment. Newer closed reduction techniques (with perfusion monitoring) have emerged as a technically straightforward means to address residual SCFE deformity while still minimizing the risk of osteonecrosis. However, limited data exists regarding the reliability of intraoperative epiphyseal perfusion monitoring to predict the development of AVN. The purpose of this study was to evaluate its reliability.

METHODS

We retrospectively reviewed all patients with unstable SCFE who underwent closed or open reduction with epiphyseal perfusion monitoring using an intracranial pressure (ICP) probe from 2015 to 2023 at a single institution with a minimum 6-month radiographic follow-up. Demographic, clinical, and radiographic data were recorded, including duration of symptoms, type of reduction, capsulotomy performed, presence of a waveform on ICP monitoring after epiphyseal fixation, and development of AVN on follow-up radiographs.

RESULTS

Our cohort included 33 hips (32 patients), of which 60.6% (n=20) were male. The average age was 12.5±1.8 years, with a median follow-up of 15.8 months. Eleven hips were treated with open reduction using the modified Dunn technique (10 hips) or anterior approach (1 hip), and 22 hips were treated with inadvertent (5 hips) or purposeful closed reduction using the Leadbetter technique (17 hips). Overall, 8 of the 33 hips in our series (24.2%) developed AVN, 6 of which (20%) had a pulsatile waveform on intraoperative epiphyseal perfusion monitoring. The overall rate of AVN after closed reductions was 31.8% (7 of 22 hips); the incidence of AVN after closed reduction with a detectable waveform was 30% (6 of 20 hips). There was no significant association between time to surgery ( P =0.416) or type of reduction ( P =0.218) and the incidence of AVN.

CONCLUSIONS

In this series, intraoperative epiphyseal perfusion monitoring did not reliably predict the development of osteonecrosis. To our knowledge, this is the first study to report AVN after demonstrable intraoperative epiphyseal perfusion following closed reduction of unstable slips.

LEVEL OF EVIDENCE

Level IV: case series-therapeutic study.

Revascularization of a Necrotic Femoral Head in Severely Slipped Capital Femoral Epiphysis With a Modified Dunn Procedure: A Case Report

Avascular necrosis, a serious slipped capital femoral epiphysis (SCFE) complication, is difficult to treat. We report a rare case of revascularization of the necrotic femoral head in a 12-year-old male patient with a severe SCFE (posterior tilting angle, 87°). We performed the modified Dunn procedure (MDP), followed by long-term unloading therapy. Blood flow to the epiphysis had partially resumed 2.3 years postoperatively. At the final 4.5-year follow-up, blood flow had been restored, leading to epiphyseal closure without significant femoral head deformity or hip pain. The patient could walk unassisted, with a flexion range of 120°. These findings support the use of the MDP with long-term unloading therapy as a potential treatment option for severe SCFE.

Modified Dunn Technique for Unstable Slipped Capital Femoral Epiphysis: A Midterm Single Center Experience

Objective  To evaluate the safety and reproducibility of the surgery for unstable slipped capital femoral epiphysis (SCFE) through the modified Dunn technique in a single center cohort from Brazil. Methods  We retrospectively analyzed a cohort of patients submitted to this procedure by a single surgeon who was a hip preservation specialist. Demographic data and radiographic angles were evaluated for the relative risk (RR) of avascular necrosis (AVN) using a log-binomial regression model with simple and random effects. Results  Among the 30 patients (30 hips) with a mean age of 11.79 years at the time of the operation, there were 17 boys and 18 left hips, which were operated on in a mean of 11.5 days after the slip. The mean follow-up was of 38 months. The preoperative Southwick angle averaged 60.69° against 4.52° postoperatively ( p  < 0.001). A larger preoperative slip angle was associated with the development of AVN (RR: 1.05; 95% confidence interval [95%CI]: 1.02-1.07; p  < 0.01). The overall AVN rate was of 26.7%. Function was good or excellent in 86% of uncomplicated hips, and poor in 87.5% of the partients who developed AVN, as graded by the Harris Hip Score. There was no statistical relationship between epiphyseal bleeding and AVN development ( p  = 0.82). Conclusion  The modified Dunn technique is associated with restoration of the femoral alignment and function after unstable SCFE, when uncomplicated. Moreover, it was shown to be reproducible in our population, with a rate of 26% of femoral head necrosis.

Presence and magnitude of anterior physeal separation in slipped upper femoral epiphysis helps identifying those at high risk for avascular necrosis

AIMS

We sought to determine if the magnitude of anterior physeal separation (APS) in slipped upper femoral epiphysis was a predictor for the subsequent development of avascular necrosis (AVN). Anterior Physeal Separation (APS) is defined as the distance between the anterior lip of the bony capital epiphysis and the lateral corresponding point of the adjacent bony metaphysis on the Lauenstein radiographic view. It represents hinging of the posterior aspect of the metaphysis with the anterior epiphysis lifting away from its adjacent metaphysis, indicating instability and potential vulnerability of the vessels.

PATIENTS AND METHODS

A retrospective review of all patients treated regionally for slipped upper femoral epiphysis over a 9 year period (2010-2018 inclusive) were identified. Data regarding demographics, radiological parameters and outcomes was recorded. APS was measured on a Launestein radiograph view, with the patient supine, the hip and knee are flexed to 40°, and the hip externally rotated 45°, with film-focus distance of 100 cm. Analysis of the APS was performed to validate a threshold above which AVN occurs.

RESULTS

We identified 147 hips in 142 patients, of which 5 had bilateral slips at the time of presentation. Average anterior physeal separation was 3.8 ± 1.8 mm, with higher grade slips having significantly greater APS values. Increased APS values were seen with Loder "unstable" slips. Seven hips (4.8%) developed AVN, and in these cases the APS was significantly larger than those who did not (8.5 ± 1.4 Vs 3.9 ± 1.7; p < 0.001). Receiver operator curve analysis demonstrated a critical value of 7.5 mm was associated with a 100% sensitivity and 98.6% specificity for AVN. We identified some grade II/moderate slips with high APS values had similar outcomes to grade III/severe slips, and therefore suggest that APS may serve to alert the surgeon on counselling patients on the risk of developing AVN and to consider strategies to minimise the risk of AVN.

CONCLUSIONS

APS is sensitive, specific, accurate and reliable for the association with AVN in SUFE. Its values closely reflect the high AVN rates seen in acute and unstable SUFE. This risk is greatest if the magnitude of APS exceeds the critical value of 7.5 mm.

Necrose avascular pós-cirurgia de Dunn modificada no tratamento do escorregamento da epífise proximal do fêmur*

Objective  The present study analyzed the incidence of epiphyseal avascular necrosis in patients with slipped capital femoral epiphysis (SCFE) treated using a modified Dunn technique. In addition, this study determined the correlation of other variables with this incidence and described treatment complications.

Methods  This is a retrospective study with 20 patients treated by the same surgical team from 2009 to 2019 and followed up for 2 to 12 years. The analysis included general features, time from presentation to surgical procedure, classification, and intraoperative blood perfusion of the epiphysis, as well as complications and their treatment.

Results  All cases were severe; 65% were acute on chronic, and 55% of the SCFEs were unstable. Our complication rate was 45%, with 5 cases of avascular necrosis, 2 cases of deep infection, 1 case of material failure, and 1 case of joint instability. The statistical analysis revealed that the risk of necrosis was higher when the surgery occurred after a long hospitalization time and there was no intraoperative epiphyseal perfusion. Four necrosis cases happened within the first 5 years, and 1 case in the last 5 years of the study.

Conclusion  Our study showed that necrosis was the most common complication. It also revealed that surgery delay and lack of intraoperative epiphysis perfusion potentially predispose to avascular necrosis. Although with no statistical significance, coxofemoral instability occurred in chronic SCFE, and surgical fixation with threaded wires was less effective than fixation with a cannulated screw.

The modified Dunn procedure should be reserved for severe cases in which other techniques are not feasible and performed by an experienced, trained, and qualified team.

Diagnosis and Management of Unstable Slipped Capital Femoral Epiphysis: A Critical Analysis Review

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An unstable slipped capital femoral epiphysis (SCFE) is characterized by the inability to walk and is associated with a high risk of osteonecrosis.

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An unstable SCFE is less common than a stable SCFE; however, the demographics are similar in both groups of patients with SCFE.

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The diagnosis of an unstable SCFE is characterized by a history of antecedent pain and the inability to walk on examination, and it is confirmed by radiographic assessment.

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Management of an unstable SCFE includes closed reduction, open reduction, and capital realignment, which have all been noted to have lower rates of osteonecrosis than reported in historic reports.

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All management approaches have certain advantages and disadvantages, and comparative studies are needed to guide clinical decision-making.

Intraoperative assessment of femoral head perfusion during surgical hip dislocation for slipped capital femoral epiphysis

Avascular necrosis is the most devastating complication of slipped capital femoral epiphysis, leading to collapse of the femoral head, increased risk of osteoarthritis and the requirement of early total hip arthroplasty. It is believed that intraoperative femoral head perfusion assessment may be an accurate predictor of post-operative avascular necrosis (radiographic collapse). At our institution, femoral head perfusion is assessed intraoperatively during all sub-capital realignment procedures. We hypothesize that our method is accurate in predicting the risk of developing post-operative avascular necrosis. In this retrospective study, we collected data from all patients that had intraoperative blood flow measurements during sub-capital realignment procedures. We correlated this with long-term radiographs looking for radiographic collapse. The intraoperative femoral head perfusion assessments during sub-capital realignment procedures for slipped capital femoral epiphysis at our institution, between January 2015 and March 2020 inclusive were assessed for reliability. In total, 26 of 35 patients had intraoperative femoral head perfusion present. Only 2 (8%) of these patients developed radiographic collapse. In contrast, 7 (78%) of the 9 patients who did not have femoral head perfusion present intraoperatively developed radiographic collapse, indicating that our method may be reliable in predicting a patient’s post-operative risk of developing avascular necrosis.

Vascular Supply to the Femoral Head in Patients With Healed Slipped Capital Femoral Epiphysis

BACKGROUND

Slipped capital femoral epiphysis (SCFE) is one of the most common hip disorders. The vascularity of the lateral epiphyseal vessels supplying the femoral head in patients with healed SCFE has not been well defined. The purpose of this study was to characterize the location and number of lateral epiphyseal vessels in young adults with healed SCFE.

METHODS

This was a retrospective study of 17 patients (18 hips) with a diagnosis of SCFE and a matched control group of 17 patients (17 hips) with developmental dysplasia of the hip. All patients underwent high-resolution contrast-enhanced magnetic resonance imaging to visualize the path of the medial femoral circumflex artery and the lateral epiphyseal arterial branches supplying the femoral head.

RESULTS

There were 5 unstable SCFEs and 13 stable SCFEs with an average slip angle of 31 degrees. (All patients had been treated with in situ pinning and screw removal). Average age at time of magnetic resonance imaging was 24.5 years (range, 15 to 34 y). The lateral epiphyseal vessels reliably inserted on the posterior-superior aspect of the femoral neck from the superior-anterior to the superior-posterior position in both the SCFE and control groups. An average of 2 (±0.8) retinacular vessels were identified in the SCFE group compared with 5.2 (±0.7) retinacular vessels in the control group (P<0.001).

CONCLUSIONS

In healed SCFE, the lateral epiphyseal vessels reliably insert in the same anatomic region as patients with hip dysplasia; however, the overall number of vessels is significantly lower.

Evolving Understanding of and Treatment Approaches to Slipped Capital Femoral Epiphysis

PURPOSE OF REVIEW

To review slipped capital femoral epiphysis (SCFE), with a focus on new insights into its etiology and evolving methods of operative fixation.

RECENT FINDINGS

The epiphyseal tubercle and its size during adolescence are paramount to understanding the mechanism of SCFE. In chronic stable SCFE, the epiphysis rotates about the tubercle protecting the lateral epiphyseal vessels from disruption. In an acute unstable SCFE, the tubercle displaces, increasing the risk of osteonecrosis, also known as avascular necrosis (AVN). Intraoperative stability suggests that stable and unstable SCFE based on ambulation may be inaccurate. For stable SCFE, in situ pinning remains the most accepted treatment for mild slips with delayed symptomatic femoroacetabular impingement (FAI) management. Treatment of moderate to severe stable slips with realignment osteotomy leads to less femoral deformity and potentially better outcomes. However, it has a higher risk of complications, including AVN and chondrolysis. Our knowledge of the etiology for SCFE is evolving. The optimal technique for operative treatment of moderate to severe SCFE is controversial and varies by center. Well-controlled studies of these patients are needed to understand the best treatment for this difficult problem. Furthermore, increasing the awareness about SCFE is paramount to allow for early recognition and treatment of deformity at its early stages and avoiding severe SCFE deformity which has been associated with worse long-term outcomes.

Outcomes after slipped capital femoral epiphysis: a population-based study with three-year follow-up

PURPOSE

To evaluate outcomes three years after treatment for slipped capital femoral epiphysis (SCFE): development of avascular necrosis (AVN), subsequent surgery, hip function and the contralateral hip.

METHODS

This prospective cohort study included a total national population of 379 children treated for SCFE between 2007 and 2013. A total of 449 hips treated for SCFE and 151 hips treated with a prophylactic fixation were identified. The Barnhöft questionnaire, a valid patient-reported outcome measure (PROM), was used.

RESULTS

In all, 90 hips had a severe slip, 61 of these were clinically unstable. AVN developed in 25 of the 449 hips. Six of 15 hips treated with capital realignment developed AVN. A peri-implant femur fracture occurred in three slipped hips and in two prophylactically pinned hips. In three of these five hips technical difficulties during surgery was identified. In 43 of 201 hips scheduled for regular follow-up a subsequent SCFE developed in the contralateral hip. Implant extraction after physeal closure was performed in 156 of 449 hips treated for SCFE and in 51 of 151 prophylactically fixed hips. Children with impaired hip function could be identified using the Barnhöft questionnaire.

CONCLUSION

Fixation in situ is justified to remain as the primary treatment of choice in SCFE. Overweight is more common in children with SCFE than in the average population. Prophylactic fixation is a safe procedure when performed using a correct technique. The number of patients who developed AVN after capital realignment is of concern. We recommend rigorous follow-up of both hips, including PROM evaluation, until physeal closure.

LEVEL OF EVIDENCE

II - prospective cohort study.

What's New in Pediatric Hip?

BACKGROUND

Developmental dysplasia of the hip (DDH), which encompasses a wide spectrum of disease from mild dysplasia to frank dislocation, is one of the most common developmental deformities of the lower extremities and one of the leading causes of future osteoarthritis and hip arthroplasty. Legg-Calvé-Perthes disease (LCPD) results from a vascular insult to the growing femoral epiphysis, which in turn can create permanent morphologic changes to the hip joint. Slipped capital femoral epiphysis (SCFE) occurs when the proximal femoral physis fails allowing the epiphysis to displace in relation to the metaphysis. Infections about the hip also create significant morbidity in the pediatric hip.

METHODS

We searched the PubMed database for all studies related to DDH, LCPD, SCFE, and pediatric hip infections that were published between July 1, 2014 and August 31, 2017. The search was limited to English articles and yielded 839 papers. This project was initiated by the Pediatric Orthopaedic Society of North America Publications Committee and was reviewed and approved by the Pediatric Orthopaedic Society of North America Presidential Line.

RESULTS

A total of 40 papers were selected for review based upon new and significant findings. Select historical manuscripts are also included to provide sufficient background information.

CONCLUSIONS

DDH, LCPD, SCFE, and infections about the hip continue to be important topics in pediatric orthopaedics and areas of vital research. This manuscript reviews the most important recent literature on the diagnosis and treatment of these pediatric hip conditions.

LEVEL OF EVIDENCE

Level V.

The modified Dunn procedure provides superior short-term outcomes in the treatment of the unstable slipped capital femoral epiphysis as compared to the inadvertent closed reduction and percutaneous pinning: a comparative clinical study

PURPOSE

The aim of this study was to compare clinical outcomes and radiographic correction after modified Dunn procedure versus inadvertent closed reduction and percutaneous pinning for the treatment of unstable slipped capital femoral epiphysis (SCFE).

METHODS

We evaluated 45 patients with unstable SCFE treated using the modified Dunn procedure (n = 27) or percutaneous pinning (n = 18) during a minimum follow-up of one year. Clinical outcomes were assessed using the Heyman and Herndon scores. The Southwick angle, alpha angle, and femoral head-neck offset were used to assess radiographic correction. The occurrence of complications and unplanned re-operations were recorded.

RESULTS

At latest follow-up, 67% (18/27) in the modified Dunn procedure group and 28% (5/18) in the in situ pinning group had good or excellent Heyman and Herndon outcomes (p = 0.016). The morphology of the femoral head and neck was improved in the modified Dunn procedure group compared to percutaneous pinning (Southwick angle, alpha angles; femoral head-neck offset; p < 0.001). The proportion of osteonecrosis (26 vs. 28%; p > 0.999) and unplanned re-operations (26 vs. 33%; p = 0.894) was similar in both groups.

CONCLUSION

Compared to inadvertent reduction and percutaneous pinning, the modified Dunn procedure provided better clinical and radiographic outcomes with similar proportion of osteonecrosis and unplanned re-operations following an unstable SCFE.

Diagnosis and treatment of slipped capital femoral epiphysis: Recent trends to note

Slipped capital femoral epiphysis (SCFE) is not frequently encountered during routine practice and diagnosis and treatment are often delayed. It is important to understand symptoms and imaging features to avoid delayed diagnosis. After the diagnosis is made correct classification of the disease is required. The classification should be based on the physeal stability in order to choose safe and effective treatment. However, surgeons should bear in mind that the assessment is challenging and actual physeal stability is not always consistent with the stability predicted by a clinical classification method.

TREATMENT OF STABLE SCFE

Closed reduction is not indicated for stable SCFE, where continuity between the epiphysis and metaphysis has not been disrupted. Treatment method(s) is (are) chosen from in-situ fixation, osteotomy and femoroacetabular impingement treatment. A single screw fixation is often used to fix the epiphysis and the dynamic method is considered especially for young patients. Traditional three-dimensional trochanteric osteotomies have been associated with procedural complexity and uncertainty. A simpler osteotomy method using an updated imaging analysis technology should be considered. Modified-Dunn procedure is indicated for a severe stable SCFE. However, caution is required because recent studies have reported a high rate of complications including postoperative femoral head avascular necrosis (AVN) and hip instability when this method is indicated for stable SCFE.

TREATMENT OF UNSTABLE SCFE

Treatment of unstable SCFE is difficult and complication rate is high. Most of unstable SCFE patients were previously treated with closed method and it was difficult to predict an occurrence of postoperative AVN. However, treatment of unstable SCFE has gradually changed in recent years and many studies have shown that physeal hemodynamics can be assessed during treatment. Preoperative assessments include contrast-enhanced MRI and bone scintigraphy. Intraoperative assessments include confirmation of bleeding after drilling the femoral head and monitoring the intracranial pressure by laser doppler flowmetry. It is expected that postoperative AVN can be prevented in many cases by performing the treatment while assessing the intraoperative physeal hemodynamics. Open surgeries have begun to be indicated in the treatment of unstable SCFE through either of anterior approach or (modified) Dunn procedure. The authors expect that recent improvements in assessment of physeal hemodynamics and open treatment method provide improved clinical outcomes in the treatment of SCFE.

Intraoperative Monitoring of Epiphyseal Perfusion in Slipped Capital Femoral Epiphysis: Surgical Technique

Introduction

Intraoperative monitoring of epiphyseal perfusion in slipped capital femoral epiphysis (SCFE) is a procedurally simple and readily accessible percutaneous technique to accurately guide decision-making and help to prevent osteonecrosis.

Indications & Contraindications

Step 1 Patient Preparation and Positioning

Following anesthesia induction, position the patient and assess the physeal stability fluoroscopically to determine the need for a reduction.

Step 2 Guidewire Placement

Place a 3.2-mm threaded guidewire from the anterolateral aspect of the femur to provide initial stability of the slipped epiphysis.

Step 3 Initial Screw Insertion

Insert a cannulated 7.0-mm stainless steel screw over the guidewire to a point just past the physis.

Step 4 Preparation and Insertion of the ICP Probe

Once the screw has been inserted to obtain provisional stability of the physis, remove the guidewire and insert a sterile ICP probe down the screw shaft to assess the epiphyseal perfusion.

Step 5 Hip Decompression

If a perfusion pressure and waveform cannot be obtained, perform decompression of the hip capsule by either aspiration or capsulotomy.

Step 6 Epiphyseal Perfusion Reassessment

Following the capsulotomy, reinsert the ICP probe and reassess the epiphyseal perfusion.

Step 7 Final Screw Advancement

Once epiphyseal blood flow can be confirmed, reintroduce the guidewire to its previous depth and advance the screw to the final measured depth.

Results

Utilizing this technique over a 5-year period, >35 patients were treated with the described technique, and 23 of them, including 29 hips, were included in our referenced prospective study³.

Pitfalls & Challenges