Stabilometry in Relation to Hip and Knee Muscle Force in Children with Surgically Treated Unilateral Slipped Capital Femoral Epiphysis.

BACKGROUND/OBJECTIVES: The main aim of our study was to analyze the stabilometric parameters in relation to hip and knee muscle force in children with unilateral slipped capital femoral epiphysis (SCFE) who had undergone surgical treatment. Another objective was to compare the stabilometry in three testing situations (eyes open, eyes closed, and head retroflexed). METHODS: In total, 26 patients with unilateral right SCFE treated via in situ fixation with one percutaneous screw performed stabilometry assessments under three different situations (with their eyes open, with their eyes closed, and with their head retroflexed) and isometric muscle force assessment of the bilateral hip flexors, extensors, abductors and adductors and bilateral knee flexors and extensors. RESULTS: No significant differences between the right side (affected hip) and left side (non-affected hip) were recorded for all of the tested muscle groups. We found significant negative correlations between the 90% confidence ellipse area (eyes open condition) and left knee extensors (p = 0.028), right knee flexors (p = 0.041), and left knee flexors (p = 0.02), respectively. When performing the comparison between the eyes open and eyes closed situations, there were significant differences in CoP path length (p < 0.0001) and maximum CoP speed (p = 0.048); the parameters increased in the eyes closed situation. CONCLUSIONS: Better postural stability is acquired when assessed with eyes open or with the head retroflexed in contrast with eyes closed testing.

Two-year 3D gait outcomes following in-situ pinning or modified Dunn procedure in children with slipped capital femoral epiphysis.

BACKGROUND: Slipped Capital Femoral Epiphysis (SCFE) is femoral head slippage off the femoral neck through the physis occurring in children aged 8-16 years. Surgical intervention is required in all paediatric cases and there is no universal agreement on choice of surgical procedure. RESEARCH QUESTION: What are the two-year 3D gait outcomes in children with SCFE who have undergone in-situ pinning (PIN) or modified Dunn procedure (MDP) compared with normative reference values? METHODS: 17 children with SCFE who had undergone PIN (n=7, slip severity mild to moderate) or MDP (n=10, slip severity moderate to severe) surgical procedures prospectively underwent a 3D gait analysis post-surgery (2∙0 ± 0∙5 years). Ten age-matched children were also recruited to provide normative reference values. The conventional gait model was modified to incorporate Hara hip equations and Lerner pelvic tracking methods. Gait Profile Scores, Gait Variable Scores, kinematics, kinetics and spatiotemporal data were calculated for each group. RESULTS: Overall gait pattern, determined by the Gait Profile Score, indicated that both SCFE groups differed from the normative reference group (PIN 6∙6 ± 2∙5°, MDP 6∙2 ± 2∙0° vs. 4∙0 ± 1∙3° norm, p<0∙05). Normalised walking speed was reduced in the MDP group (0∙40 ± 0∙04) compared to the normative reference group (0∙46 ± 0∙06; p=0∙032). SIGNIFICANCE: Gait patterns of children with SCFE treated with PIN was more markedly altered than that of children with SCFE treated with MDP, despite having lower SCFE severity. Increased external hip rotation observed in the PIN group may be a pre-cursor for osteoarthritis in adulthood. Therefore the use of the corrective MDP which normalises hip rotation may be beneficial for reducing functional impairments.

Slipped capital femoral epiphysis: emphasis on early recognition and potential pitfalls.

Slipped capital femoral epiphysis is a shearing injury through the growth plate of the proximal femur and is the most common hip disorder in adolescence. Delays in diagnosis persist across practice settings despite ongoing innovations in imaging. Recent insights into pathomechanics highlight the importance of femoral head surface morphology and rotational microinstability centered at the epiphyseal tubercle in causing early physeal changes, which can be detected on imaging prior to frank slip. Scrutiny of physeal morphology and comparison to the contralateral hip is critical at all stages of disease progression, and improper technique may result in undue diagnostic delay. Selective use of cross-sectional imaging can be helpful for troubleshooting equivocal early slips and can inform operative technique and adjuvant therapy candidacy in more severe cases. This review provides a comprehensive approach to imaging suspected slipped capital femoral epiphysis, with an emphasis on early detection and potential pitfalls.

Favourable outcome of severe, unstable grade III slipped capital femoral epiphysis managed by closed reduction percutaneous pinning with mid-term follow up: A case report and literature review.

INTRODUCTION AND IMPORTANCE: Slipped capital femoral epiphysis (SCFE) is one of the most common hip pathology in adolescents. Outcome of SCFE management largely depends on the grading of the pathology. Severe, unstable SCFE poses high risk for avascular necrosis (AVN). The objective of this study is to report a good outcome without AVN in an acute, unstable, high grade SCFE managed by closed reduction and percutaneous pinning along with factors that need to be given consideration. CASE PRESENTATION: A 13 years old boy was unable to bear weight due to severe pain on right hip after trauma since 2 weeks. Patient was diagnosed with acute, unstable high grade SCFE, patient underwent closed reduction and percutaneous pinning (CRPP) using cannulated screw and K wire augmented with spica cast. At 12 weeks patient was already fully active. At 18 month follow up there was no sign of AVN with full hip range of movement. CLINICAL DISCUSSION: Treatment for unstable, severe SCFE is still challenging. Unreduced severe slippage will deliver serious impingement and end up with early degenerative arthritis. The magnitude of reduction in a severe, unstable SCFE poses high risk for AVN. While some studies claimed reduction is justified only when it is serendipitous, we successfully and purposely performed CRPP. CONCLUSION: Even after 2 weeks from onset, an acute and severe slippage can still be reduced closely and fixed percutaneously. The hip regain full range of motion with no sign of AVN on x ray at 18 months follow up.

Comparison of different radiographic methods to measure the slip angle in children with slipped capital femoral epiphysis (SCFE).

BACKGROUND: The management of patients with slipped capital femoral epiphysis (SCFE) requires imaging diagnostics of good quality and accurate measurement of the degree of slippage. In Sweden, three different radiological methods are commonly used: the calcar femorale method; the Billing method; and the Head-shaft angle described by Southwick. PURPOSE: To evaluate whether any of the three most common methods used in Sweden to measure the slip angle was more useful and reproducible than the others. MATERIAL AND METHODS: Two experienced orthopaedists measured the slip angle in preoperative hip radiographs. Intra- and inter-observer variability between the two experienced observers and the reported value by clinicians who treated the child with SCFE was evaluated. RESULTS: The intraclass correlation coefficient (ICC) confidence interval (CI) between the two experienced observers and the reporting clinicians overlapped for the three methods. In 37% of the cases, the difference was more than 5° between the experienced observers' measurement and the reported value by clinicians. The two experienced orthopaedists' intra- and inter-observer variability was low. CONCLUSION: The observer's experience is more important than the method of choice when measuring the slip angle in SCFE. The research group recommends the calcar femorale method due to its feasibility on the versatile and commonly used frog leg lateral view.

Analysis of risk factors for difficult implant removal in children with slipped capital femoral epiphysis treated by cannulated screws.

Introduction: Cannulated screws are widely used in the treatment of slipped capital femoral epiphysis, which can be removed after physeal closure on patient's request. This study aimed to analysis the potential risk factors for difficult removal in children with slipped capital femoral epiphysis treated by cannulated screws. Patients and methods: This study enrolled 32 hips that had undergone removal of cannulated screws after treatment of slipped capital femoral epiphysis at our department. The primary outcomes were the difficult screw removal. The secondary outcomes were functional outcome assessed by using a modified Harris Hip Score and complications of fractures and surgical site infection. Related risk factors for difficult removal were recorded and analyzed by multivariable logistic regression. Results: In total, 32 hips were evaluated, with a mean age of 14.9 ± 1.3 years old (range, 13-19 years). Six (18.8%) hips presented with difficult removal, including 4 cases of screws' slip and 2 breakages. The average implantation time in the difficult removal group (5.7 ± 1.0) was also significantly longer than that in the easily removed group (3.8 ± 0.9, p = 0.001). The mean surgical time in patients with difficult removal was 66.3 ± 11.6 min, which was also significantly longer than that (54.8 ± 8.3) in the other patients (p = 0.008). The duration of screw implantation was an independent risk factor for difficult removal. Conclusions: Prolonged screw duration was a predictor for difficult removal in children with slipped capital femoral epiphysis treated by cannulated screws. An early surgery after physeal closure might benefit those with a request for screw removal.

Does spinopelvic alignment affect femoral head cartilage and the proximal femoral physis in slipped capital femoral epiphysis? A finite element analysis.

BACKGROUND: Slipped capital femoral epiphysis is a prevalent pediatric hip disorder. Recent studies suggest the spine's sagittal profile may influence the proximal femoral growth plate's slippage, an aspect not extensively explored. This study utilizes finite element analysis to investigate how various spinopelvic alignments affect shear stress and growth plate slip. METHODS: A finite element model was developed from CT scans of a healthy adult male lumbar spine, pelvis, and femurs. The model was subjected to various sagittal alignments through reorientation. Simulations of two-leg stance, one-leg stance, walking heel strike, ascending stairs heel strike, and descending stairs heel strike were conducted. Parameters measured included hip joint contact area, stress, and maximum growth plate Tresca (shear) stress. FINDINGS: Posterior pelvic tilt cases indicated larger shear stresses compared to the anterior pelvic tilt variants except in two leg stance. Two leg stance resulted in decreases in the posterior tilted pelvi variants hip contact and growth plate Tresca stress compared to anterior tilted pelvi, however a combination of posterior pelvic tilt and high pelvic incidence indicated larger shear stresses on the growth plate. One leg stance and heal strike resulted in higher shear stress on the growth plate in posterior pelvic tilt variants compared to anterior pelvic tilt, with a combination of posterior pelvic tilt and high pelvic incidence resulting in the largest shear. INTERPRETATION: Our findings suggest that posterior pelvic tilt and high pelvic incidence may lead to increased shear stress at the growth plate. Activities performed in patients with these alignments may predispose to biomechanical loading that shears the growth plate, potentially leading to slip.

Case report: Slipped capital femoral epiphysis: a rare adverse event associated with FGFR tyrosine kinase inhibitor therapy in a child.

We report a case of slipped capital femoral epiphysis (SCFE), an on target skeletal toxicity of a pan-FGFR TKI inhibitor, erdafitinib. A 13-year-old boy was diagnosed to have an optic pathway/hypothalamic glioma with signs of increased intracranial pressure and obstructive hydrocephalus requiring placement of ventriculo-peritoneal (VP) shunt. Sequencing of the tumor showed FGFR1-tyrosine kinase domain internal tandem duplication (FGFR1-KD-ITD). He developed hypothalamic obesity with rapid weight gain and BMI >30. At 12 weeks of treatment with erdafitinib, he developed persistent knee pain. X-ray of the right hip showed SCFE. Erdafitinib was discontinued, and he underwent surgical pinning of the right hip. MRI at discontinuation of erdafitinib showed a 30% decrease in the size of the tumor, which has remained stable at 6 months follow-up. Our experience and literature review suggest that pediatric patients who are treated with pan-FGFR TKIs should be regularly monitored for skeletal side effects.

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.

Static Plantar Pressure under Different Conditions in Children with Surgically Treated Unilateral Slipped Capital Femoral Epiphysis.

BACKGROUND: Slipped capital femoral epiphysis (SCFE) is the most common hip disease during infancy and adolescence. Our study aimed to analyze static plantar pressure in children with surgically treated unilateral SCFE. METHODS: Twenty-two children with right SCFE with in situ fixation with one percutaneous screw were assessed by PoData plantar pressure analysis under three different conditions (open eyes, eyes closed, and head retroflexed). RESULTS: The total foot loading was significantly higher on the unaffected limb compared with the affected one for all the three testing conditions (p < 0.05). When assessing the differences between testing conditions, there were no significant differences for the right and left foot loadings, or for the three sites of weight distribution, except for the right fifth metatarsal head (lower loading in eyes-closed condition in comparison to eyes open, p = 0.0068), left fifth metatarsal head (increased loading in head-retroflexed condition in comparison to eyes open, p = 0.0209), and left heel (lower loading in head-retroflexed condition in comparison to eyes open, p = 0.0293). CONCLUSION: Even after a successful surgical procedure, differences in foot loading can impact the postural static activities in different conditions (natural eyes-open, eyes-closed, or head-retroflexed posture).

Delayed slipped capital femoral epiphysis after orif for subtrochanteric femur fracture.

INTRODUCTION AND IMPORTANCE: Slipped capital femoral epiphysis (SCFE) is a common phenomenon of the proximal femur in adolescents with an unclear etiology. It is more common in boys than girls and there does seem to be some predilection to race, weight, and age (Lehmann et al., 2006 [7]). CASE PRESENTATION: We reported a 13-year-old boy who presented with unilateral SCFE following subtrochanteric left femur fracture, which was fixed by blade plate 6 monthes before the SCFE. The SCFE fixed by two cannulated screw. We aim to discuss the possible link between the surgical technique used for proximal femur fractures and the delayed onset of SCFE. CLINICAL DISCUSSION: Slipped capital femoral epiphysis (SCFE) after treatment of subtrochanteric fracture can be caused by inadequate treatment of the fracture. Orthopedic surgeons should be aware of this complication so that they can promptly recognize this complication and treat it urgently (Chinoy et al., 2020). CONCLUSION: Slipped capital femoral epiphysis (SCFE) after treatment of subtrochanteric fracture is a very rare condition, that it can be prevented by proper reduction and fixation of the fracture using appropriate osteosynthesis material.

Vara Deformity and Subluxed Humeral Heads: An Unusual Sign in Pseudohypoparathyroidism.

Pseudohypoparathyroidism is a rare disorder characterized by end-organ resistance to intact parathyroid hormone (PTH) and concomitant laboratory findings of hypocalcemia and hyperphosphatemia. Radiologic evidence of the disease may manifest as a variety of bone abnormalities. This case describes an 11-year-old female with a history of repaired bilateral slipped capital femoral epiphysis who presented with a limited range of motion of the bilateral upper extremities. Laboratory findings were consistent with pseudohypoparathyroidism. Radiographs revealed subchondral resorption of bilateral clavicular heads and multiple ribs and band lucencies of proximal humeral metaphyses, along with vara deformity and inferior subluxation of the humeral heads. This presentation adds to the spectrum of potential radiographic manifestations of pseudohypoparathyroidism.

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.

The clinical value of preoperative 3D planning and 3D surgical guides for Imhäuser osteotomy in slipped capital femoral epipysis: a retrospective study.

BACKGROUND: Accurate repositioning of the femoral head in patients with Slipped Capital Femoral Epiphysis (SCFE) undergoing Imhäuser osteotomy is very challenging. The objective of this study is to determine if preoperative 3D planning and a 3D-printed surgical guide improve the accuracy of the placement of the femoral head. METHODS: This retrospective study compared outcome parameters of patients who underwent a classic Imhäuser osteotomy from 2009 to 2013 with those who underwent an Imhäuser osteotomy using 3D preoperative planning and 3D-printed surgical guides from 2014 to 2021. The primary endpoint was improvement in Range of Motion (ROM) of the hip. Secondary outcomes were radiographic improvement (Southwick angle), patient-reported clinical outcomes regarding hip and psychosocial complaints assessed with two questionnaires and duration of surgery. RESULTS: In the 14 patients of the 3D group radiographic improvement was slightly greater and duration of surgery was slightly shorter than in the 7 patients of the classis Imhäuser group. No difference was found in the ROM, and patient reported clinical outcomes were slightly less favourable. CONCLUSIONS: Surprisingly we didn't find a significant difference between the two groups. Further research on the use of 3D planning an 3D-printed surgical guides is needed. TRIAL REGISTRATION: Approval for this study was obtained of the local ethics committees of both hospitals.

The Medium- to Long-Term Results of Vascular-Sparing Subcapital Osteotomy (VASSCO) for Pediatric Patients with Chronic Slipped Capital Femoral Epiphysis.

Background: In patients affected by chronic slipped capital femoral epiphysis (C-SCFE), the performance of a subcapital osteotomy is an effective procedure to correct the deformity at the proximal femur. However, the rate of postoperative complications is very high, with iatrogenic avascular necrosis of the femoral head (AVN) being the most bothersome. To overcome the risk of AVN, the modified Dunn procedure according to Ganz and, more recently, the Vascular Sparing Subcapital Osteotomy (VASSCO) technique have been proposed; however, only short-term follow-up studies are available on the latter technique being used. The aim of this study is therefore to show our mid-term clinical and radiological results with the VASSCO technique. Materials and Methods: A total of 26 patients underwent VASSCO for moderate or severe stable C-SCFE between 2012 and April 2016 with an average 10-year follow-up (range 8-12 years). The outcomes was evaluated using the HHS and pre- and postoperative ROM. The radiological outcomes and complications were collected. Results: No major intraoperative complications occurred; three patients reported postoperative transient apraxia of the lateral femoral cutaneous nerve, which completely recovered in six months. All the radiological outcomes showed substantial improvement postoperatively. One case patient developed AVN of the femoral head and required a total hip arthroplasty after 12 years. Conclusions: The current data suggest that VASSCO osteotomy is a reliable technique with very good clinical results at mid-term follow-up; it could be considered a valuable alternative to using more complex techniques to restore the proximal femoral anatomy in moderate to severe C-SCFE.

Slipped capital femoral epiphysis in a 5-year-old boy with cerebral palsy on valproic acid and levetiracetam for epilepsy: a case report.

This study presents a rare case of unilateral slipped capital femoral epiphysis treated surgically in a 5-year-old boy with cerebral palsy who was born at 27 weeks' gestation and developed grade III intraventricular haemorrhage and periventricular leucomalacia and was on antiepileptic drugs, including valproic acid and levetiracetam for >3 years. The patient had no history of endocrine, renal, and significant familial diseases.

Limited angular remodelling after in-situ fixation for slipped capital femoral epiphysis : A study on radiographs from the Swedish pediatric orthopaedic quality registry for SCFE.

BACKGROUND: In Sweden, most children with slipped capital femoral epiphysis (SCFE) are operated on with a single smooth pin or a short-threaded screw, allowing further growth of the femoral neck. Using the Swedish Pediatric Orthopaedic Quality registry, SPOQ, we investigated whether angular remodelling occurs adjacent to the proximal femoral epiphysis after fixation of SCFE using implants, allowing continued growth of the femoral neck. METHODS: During 2008-2010 a total national population of 155 children were reported to the SPOQ registry. Following our strict inclusion criteria, radiographs of 51 hips were further assessed. The lateral Head Shaft Angle (HSA), the Nötzli 3-point α-angle, the anatomic α-angle, and the Anterior Offset Ratio (AOR) on the first postoperative radiographs and at follow-up were measured to describe the occurrence of remodelling. Slip severity was categorised as mild, moderate or severe according to postoperative HSA. RESULTS: Mean and SD values for the change in HSA were 3,7° (5,0°), for 3-point α-angle 6,8° (8,9°), and anatomic α-angle 13,0° (16,3°). The overall increase in AOR was 0,038 (0.069). There were no significant differences between the slip severity groups. CONCLUSIONS: We found limited angular remodelling after in situ fixation with smooth pins or short threaded screws for SCFE. The angular remodelling and the reduction of the CAM deformity was less than previously described after fixation of SCFE with similar implants. Results about the same magnitude with non-growth sparing techniques suggest that factors other than longitudinal growth of the femoral neck are important for angular remodelling.

Hip Impingement of severe SCFE patients after in situ pinning causes decreased flexion and forced external rotation in flexion on 3D-CT.

Introduction: In situ pinning is an accepted treatment for stable slipped capital femoral epiphysis. However, residual deformity of severe slipped capital femoral epiphysis can cause femoroacetabular impingement and forced external rotation. Purpose/questions: The aim of this study was to evaluate the (1) hip external rotation and internal rotation in flexion, (2) hip impingement location, and (3) impingement frequency in early flexion in severe slipped capital femoral epiphysis patients after in situ pinning using three-dimensional computed tomography. Patients and methods: A retrospective Institutional Review Board-approved study evaluating 22 patients (26 hips) with severe slipped capital femoral epiphysis (slip angle > 60°) using postoperative three-dimensional computed tomography after in situ pinning was performed. Mean age at slipped capital femoral epiphysis diagnosis was 13 ± 2 years (58% male, four patients bilateral, 23% unstable, 85% chronic). Patients were compared to contralateral asymptomatic hips (15 hips) with unilateral slipped capital femoral epiphysis (control group). Pelvic three-dimensional computed tomography after in situ pinning was used to generate three-dimensional models. Specific software was used to determine range of motion and impingement location (equidistant method). And 22 hips (85%) underwent subsequent surgery. Results: (1) Severe slipped capital femoral epiphysis patients had significantly (p < 0.001) decreased hip flexion (43 ± 40°) and internal rotation in 90° of flexion (-16 ± 21°, IRF-90°) compared to control group (122 ± 9° and 36 ± 11°). (2) Femoral impingement in maximal flexion was located anterior to anterior-superior (27% on 3 o'clock and 27% on 1 o'clock) of severe slipped capital femoral epiphysis patients and located anterior to anterior-inferior (38% on 3 o'clock and 35% on 4 o'clock) in IRF-90°. (3) However, 21 hips (81%) had flexion < 90° and 22 hips (85%) had < 10° of IRF-90° due to hip impingement and 21 hips (81%) had forced external rotation in 90° of flexion (< 0° of IRF-90°). Conclusion: After in situ pinning, patient-specific three-dimensional models showed restricted flexion and IRF-90° and forced external rotation in 90° of flexion due to early hip impingement and residual deformity in most of the severe slipped capital femoral epiphysis patients. This could help to plan subsequent hip preservation surgery, such as hip arthroscopy or femoral (derotation) osteotomy.

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.