High Survivorship and Little Osteoarthritis at 10-year Followup in SCFE Patients Treated With a Modified Dunn Procedure

Medium-long-term follow-up of slipped capital femoral epiphysis treated with in situ fixation and patient-acceptable symptom state evaluation

This study evaluates the Patient Acceptable Symptom State (PASS) in patients with slipped capital femoral epiphysis (SCFE) treated with in situ fixation, focusing on medium to long-term outcomes and quality of life. Its primary goal is to establish a subjective well-being cutoff, using subjective methods and the iHOT33 scale, for assessing patients in future studies. Additionally, it explores functionality differences between mild and moderate-severe SCFE, case series epidemiology and potential complications. A retrospective analysis of 63 patients (73 hips), treated for SCFE between 2000 and 2017 at our facility using in situ fixation, was conducted. These patients underwent clinical, anamnestic, and radiological assessments, with PASS determined based on iHOT33 questionnaire results and statistical analysis. The mean age at surgery was 12.95 years (±1.64, range 9-17), with an average follow-up of 11 years (±4.60, range 5-20). At follow-up, 87% of patients reported achieving PASS, with higher iHOT33 scores correlating to PASS. A cutoff of >68 on the iHOT33 scale showed strong predictive ability for assessing PASS (area under the curve 0.857, 88.89% sensitivity, 79.69% specificity). The findings indicate that 87% of patients achieved PASS at medium to long-term follow-up, with better clinical function than those who did not report PASS. The iHOT33 scale's effectiveness in predicting PASS, especially with a cutoff of >68, suggests this method's efficacy. Given these positive outcomes, including in moderate-severe cases treated with in situ fixation, this approach is considered a viable therapeutic option.

Modified Dunn Procedure for Open Reduction of Chronic Slipped Capital Femoral Epiphysis

Background

Abnormal femoral head anatomy following moderate-to-severe slipped capital femoral epiphysis (SCFE) can lead to femoroacetabular impingement and premature osteoarthritis4-10. Surgical correction at the deformity site through capital reorientation has the potential to fully ameliorate this but has traditionally been associated with high rates of osteonecrosis11-15. The modified Dunn procedure has the potential to restore anatomy in hips with SCFE while protecting the blood supply to the femoral head.

Description

A surgical dislocation of the hip is performed according to the technique described by Ganz et al.16. The remaining posterosuperior portion of the greater trochanter is trimmed to the level of the femoral neck by subperiosteal bone removal performed in an inside-out manner. The periosteum of the femoral neck is gradually elevated. The resulting soft-tissue flap, consisting of the retinaculum and external rotators, holds the blood vessels supplying the epiphysis. The femoral epiphysis is pinned in situ (in unstable cases) with threaded Kirschner wires, the ligamentum teres is transected, and the femoral head is dislocated. With the femoral neck exposed, the epiphysis is gradually mobilized from the metaphysis, allowing exposure of the residual femoral neck and inspection of any posteroinferior callus. To avoid tension on the retinacular vessels during reduction of the epiphysis, the posterior neck callus is completely excised. The remaining physis is removed with use of a burr while holding the epiphysis stable. The epiphysis is gently reduced onto the femoral neck, avoiding tension on the retinacular vessels. If tension is noted, the femoral neck is rechecked for residual callus, which is excised. If no callus is found, the neck may be carefully shortened in order to minimize tension. Epiphyseal fixation is achieved with use of a 3-mm fully threaded wire inserted antegrade through the fovea to the lateral cortex below the greater trochanter. A second wire is inserted retrograde under fluoroscopy. After reducing the hip, the capsule is closed and the greater trochanter is reattached with use of 3.5-mm cortical screws.

Alternatives

Alternatives include nonoperative treatment, in situ fixation (e.g., pinning or screw fixation), gentle closed reduction with pinning, and triplanar trochanteric osteotomy (e.g., Imhauser or Southwick osteotomies).

Rationale

In situ pinning of mild-to-moderate, stable SCFE yields good long-term results with low rates of osteonecrosis9. Treatment of higher-grade SCFE without reduction aims to avoid osteonecrosis and assumes that the proximal femoral deformity will remodel; however, the head-neck offset will remain abnormal, risking impingement and early-onset osteoarthritis5,8. The procedure described in the present article allows anatomic reduction of the epiphysis with a low risk of osteonecrosis. Surgical dislocation of the hip16 with development of an extended retinacular soft-tissue flap17 provides extensive subperiosteal exposure of the circumferential femoral neck and preserves the vulnerable blood supply to the epiphysis18. The Dunn subcapital realignment procedure15 with callus removal and slip angle correction allows anatomic restoration of the proximal femur.

Expected Outcomes

Reported results of various centers performing the procedure vary greatly with regard to the number of hips treated and the follow-up time. Most studies have been retrospective and have lacked a control group. The reported risk of osteonecrosis ranges from 0% to 25.9%19, with the wide range most likely because of the challenging nature of the technique, the low number of cases per surgeon, and the long learning curve associated with the procedure. In centers with extensive experience in pediatric hip-preserving surgery, the reported rate of osteonecrosis is low3. Studies with mid to long-term follow-up have shown no conversion to total hip arthroplasty3,20,21, but residual deformities can persist, and subsequent surgery is possible.

Important Tips

Extensive experience in surgical hip dislocation and retinacular flap development is a prerequisite for successful outcomes and low rates of osteonecrosis.Sufficient callus and physeal remnant resections are needed to avoid tension on the retinacular vessels during epiphyseal reduction.The skin incision should be centered over the greater trochanterThe Gibson interval must be carefully prepared for adequate release and to avoid injury.Tension on the periosteal flap should be avoided to prevent stress on the retinacular vessels.

Acronyms and Abbreviations

AP = anteroposteriorAVN = avascular necrosis (i.e., osteonecrosis)CI = confidence intervalCT = computed tomographyK-wire = Kirschner wireMRI = magnetic resonance imagingOA = osteoarthritisSHD = surgical hip dislocationTHA = total hip arthroplastyVTE = venous thromboembolism.

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.

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.

Changing Treatment Philosophy of Slipped Capital Femoral Epiphysis (SCFE) after Introduction of the Modified Dunn Procedure (MDP): Our Experience with MDP and Its Complications

BACKGROUND

The modified Dunn procedure (MDP) has become popular during the last 16 years to treat severely displaced slipped capital femoral epiphysis (SCFE) while "in situ" pinning (ISP) has remained valid to treat mild to moderate SCFE, although the indication limit of the Southwick angle (SA) has not yet been established for either procedure. In this context, we reviewed two cohorts of patients with SCFE, one treated by ISP and the other by MDP. We also tried to better elucidate the etiopathogenesis of hip instability, a severe complication of MDP.

METHODS

Fifty-one consecutive patients with 62 hips affected by SCFE were treated by us from 2015 to 2019: 48 hips with a SA ≤ 40° had ISP while 14, with the SA > 40°, had MDP. The latter also had a CT scan to better investigate the SCFE morphology. Results were assessed using the Harris Hip Score.

RESULTS

The mean length of follow up of the two cohorts was 5.4 years (range: 3 to 8 years). Of the 35 hips operated by ISP with a full follow-up evaluation, 30 had an excellent or good result, 3, fair, and 2, poor. Of the 14 hips that underwent MDP, 11 had an excellent or good result, 1, fair, and 2, poor. A CT scan showed femoro-acetabular incongruency in two unstable hips following MDP.

CONCLUSIONS

We performed ISP in chronic SCFE with the SA ≤ 40° and MDP in acute and chronic SCFE with the SA > 40°, with satisfactory results. In both acute-on-chronic and chronic long-lasting SCFE with severe displacement, planned for MDP, a CT scan should be carried out to evaluate possible femoro-acetabular incongruency that may cause hip instability.

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.

A bibliometric analysis and visualization of research trends on surgical hip dislocation

Surgical hip dislocation (SHD) is a powerful and safe approach used to address pathologic lesions around the hip joint, and therefore, many studies have been conducted in this field. However, no bibliometric studies regarding the global research trend concerning SHD have been studied yet. This study aims to determine the research status in the field of SHD research between 2001 and 2021. The publications related to SHD from 2001 to 2021 were retrieved from the Web of Science Core Collection. Three bibliometric tools were used for this study. The main analyses include publication counts, contributions of countries, institutions, authors, journals and funding agencies, as well as analyses on clustering of references and keywords. In total, 498 articles were identified. The annual publication counts of SHD showed an ascending tendency as a whole. The United States has the most prominent contributions, with the most number of publications and the highest value of H-index. The University of Bern was the organization that produced the most literature. Professors Ganz R, Siebenrock KA, Tannast M, Steppacher SD and Leunig M were the core authors in this field. The most productive journal was Clinical Orthopaedics and Related Research. Burst keyword detection suggested that the following research directions, including 'surgical hip dislocation', 'outcome', 'fixation' and 'pain', are considered the research hotspots and deserve more attention. In conclusion, this is the first bibliometric analysis that provides a comprehensive overview of SHD research, which may assist investigators in exploring new directions for this technique.

Modified Dunn procedure versus percutaneous pinning in moderate/severe stable slipped capital femoral epiphyses

BACKGROUND

The modified Dunn procedure (MDP) has risen enthusiasm in treating slipped capital femoral epiphyses (SCFE) due to the anatomic reduction and high patients' satisfaction rates at long-term follow-up. Main aim of this study is to compare clinical and radiographic outcomes of 2 cohorts with moderate to severe stable SCFE treated by MDP and in situ fixation.

METHODS

Medical records were analysed to collect demographic data, comorbidities and time from slip to surgery. The collected postoperative data were: avascular necrosis (AVN); complications; progression of osteoarthritis and subsequent procedures. Southwick angles (SA), alpha angles and Klein line were measured on the preoperative x-rays, on the immediate postoperative period and at the latest follow-up. Outcomes scores were recorded by the following questionnaires: the Harris Hip Score, the Hip disability and Osteoarthritis Outcome Score, the Merle d'Aubigné and Postel score and the Western Ontario and McMaster Universities Arthritis Index. Kaplan-Meier survivorship curve was calculated.

RESULTS

We compared 81 hips treated by MDP with 22 hips treated by in situ pinning (PS) for moderate/severe stable SCFE. No significant differences were found between the 2 groups in terms of age, BMI, comorbidities and preoperative slip angles. At the latest follow-up, postoperative anteroposterior mean slip angles were respectively 6.2 and 19.9° in MDP and PS group (p = 0.3). Slip angles in frog lateral view were 11° in the MDP group and 39.7° in the PS group (p = 0.2). MDP group achieved better correction angles on frog leg view (11° vs. 39.7°; p < 0.001). There was no statistically significant difference in the occurrence of AVN among both groups (19.7% MDP group vs. 31.8% PS group) (p = 0.2).

CONCLUSIONS

The MDP in treating severe stable SCFE showed the best deformities corrections in conjunction with the highest functional scores at long-term follow-up and similar rates of osteonecrosis compared to in situ fixation.

Limited Hip Flexion and Internal Rotation Resulting From Early Hip Impingement Conflict on Anterior Metaphysis of Patients With Untreated Severe SCFE Using 3D Modelling

INTRODUCTION

Slipped capital femoral epiphysis (SCFE) is the most common hip disorder in adolescent patients that can result in complex 3 dimensional (3D)-deformity and hip preservation surgery (eg, in situ pinning or proximal femoral osteotomy) is often performed. But there is little information about location of impingement.Purpose/Questions: The purpose of this study was to evaluate (1) impingement-free hip flexion and internal rotation (IR), (2) frequency of impingement in early flexion (30 to 60 degrees), and (3) location of acetabular and femoral impingement in IR in 90 degrees of flexion (IRF-90 degrees) and in maximal flexion for patients with untreated severe SCFE using preoperative 3D-computed tomography (CT) for impingement simulation.

METHODS

A retrospective study involving 3D-CT scans of 18 patients (21 hips) with untreated severe SCFE (slip angle>60 degrees) was performed. Preoperative CT scans were used for bone segmentation of preoperative patient-specific 3D models. Three patients (15%) had bilateral SCFE. Mean age was 13±2 (10 to 16) years and 67% were male patients (86% unstable slip, 81% chronic slip). The contralateral hips of 15 patients with unilateral SCFE were evaluated (control group). Validated software was used for 3D impingement simulation (equidistant method).

RESULTS

(1) Impingement-free flexion (46±32 degrees) and IRF-90 degrees (-17±18 degrees) were significantly ( P <0.001) decreased in untreated severe SCFE patients compared with contralateral side (122±9 and 36±11 degrees).(2) Frequency of impingement was significantly ( P <0.001) higher in 30 and 60 degrees flexion (48% and 71%) of patients with severe SCFE compared with control group (0%).(3) Acetabular impingement conflict was located anterior-superior (SCFE patients), mostly 12 o'clock (50%) in IRF-90 degrees (70% on 2 o'clock for maximal flexion). Femoral impingement was located on anterior-superior to anterior-inferior femoral metaphysis (between 2 and 6 o'clock, 40% on 3 o'clock and 40% on 5 o'clock) in IRF-90 degrees and on anterior metaphysis (40% on 3 o'clock) in maximal flexion and frequency was significantly ( P <0.001) different compared with control group.

CONCLUSION

Severe SCFE patients have limited hip flexion and IR due to early hip impingement using patient-specific preoperative 3D models. Because of the large variety of hip motion, individual evaluation is recommended to plan the osseous correction for severe SCFE patients.

LEVEL OF EVIDENCE

Level III.

Screw Thread Configuration Has No Effect on Outcomes of In Situ Fixation for Stable Slipped Capital Femoral Epiphysis

BACKGROUND

No consensus exists regarding the optimal surgical management of slipped capital femoral epiphysis (SCFE). Treatment goals include avoiding slip progression and sequelae such as avascular necrosis (AVN). Factors associated with surgical implants merit further research. This study investigates the effect of screw thread configuration and the number of screws on surgical outcomes.

METHODS

A total of 152 patients undergoing cannulated, stainless steel, in situ screw fixation of SCFE between January 2005 and April 2018 were included. Procedure laterality, screw number and thread configuration (partially threaded/fully threaded), bilateral diagnosis, Loder classification, final follow-up, patient demographics, and endocrinopathy history were analyzed. Primary outcomes were return to the operating room (ROR), AVN, hardware failure/removal, and femoroacetabular impingement (FAI).

RESULTS

Most patients received a single (86.2%), partially threaded (81.6%) screw; most were unilateral (67.8%) and stable (79.6%). Mean follow-up was 2.0±2.7 years, with a 15.8% rate of ROR, 5.3% exhibiting AVN, 6.6% exhibiting FAI, and 9.2% experiencing hardware failure/removal. Number of screws was the sole predictor of ROR [odds ratio (OR)=3.35, 95% confidence interval (CI): 1.18-9.49]. Unstable SCFE increased the odds of AVN (OR=38.44; 95% CI: 4.35-339.50) as did older age (OR=1.43, 95% CI: 1.01-2.03). Female sex increased risk for FAI (OR=4.87, 95% CI: 1.20-19.70), and bilateral SCFE elevated risk for hardware failure/removal versus unilateral SCFE (OR=4.41, 95% CI: 1.39-14.00). Screw thread configuration had no significant effect on any outcome (for each, P ≥0.159).

CONCLUSIONS

Rates of ROR, AVN, FAI, and hardware failure/removal did not differ between patients treated with partially threaded or fully threaded screws. The use of 2 screws was associated with an increased likelihood of ROR. These findings suggest that screw thread configuration has no impact on complication rates, whereas screw number may be an important consideration in SCFE fixation.

LEVEL OF EVIDENCE

Level III-retrospective cohort study.

Minimal Out-Toeing and Good Hip Scores of Severe SCFE Patients Treated With Modified Dunn Procedure and Contralateral Prophylactic Pinning at Minimal 5-year Follow up

BACKGROUND

Slipped capital femoral epiphyses (SCFE) is associated with out-toeing of the foot and external rotation gait. But it is unknown if SCFE patients treated with the modified Dunn procedure have out-toeing at follow up.Therefore, we used instrumented gait analysis and questioned (1) do severe SCFE patients treated with a modified Dunn procedure have symmetrical foot progression angle (FPA) compared with contralateral side and compared with asymptomatic volunteers (2) what is the prevalence of out-toeing gait and what are the outcome socres at follow up.

METHODS

Gait analysis of 22 patients (22 hips) treated with an unilateral modified Dunn procedure for severe SCFE (slip angle >60 degrees, 2002 to 2011) was retrospectively evaluated. Of 38 patients with minimal 5-year follow up, 2 hips (4%) had avascular necrosis of the femoral head and were excluded for gait analysis. Twenty-two patients were available for gait analysis at follow up (mean follow up of 9±2 y). Mean age at follow up was 22±3 years. Mean preoperative slip angle was 64±8 degrees (33% unstable slips) and decreased postoperatively (slip angle of 8±4 degrees). Gait analysis was performed with computer-based instrumented walkway system (GAITRite) to measure FPA with embedded pressure sensors. Patients were compared with control group of 18 healthy asymptomatic volunteers (36 feet, mean age 29±6 y).

RESULTS

(1) Mean FPA of SCFE patients (3.6±6.4 degrees) at follow up was not significantly different compared with their contralateral side (5.6±5.5 degrees) and compared with FPA of controls (4.0±4.5 degrees). (2) Of the 22 SCFE patients, most of them (19 hips, 86%) had normal FPA (-5 to 15 degrees), 2 patients had in-toeing (FPA<-5 degrees) and 1 had out-toeing (FPA >15 degrees) and was not significantly different compared with control group. (3) Mean modified Harris hip score (mHHS) was 93±11 points, mean Hip Disability and Osteoarthritis Outcome Score (HOOS) score was 91±10 points. Three patients (14%) had mHHS <80 points and walked with normal FPA. The 2 patients with in-toeing and one patient with out-toeing had mHHS >95 points.

CONCLUSIONS

Patients with severe SCFE treated with modified Dunn procedure had mostly symmetrical FPA and good hip scores at long term follow up. This is in contrast to previous studies. Although 1 patient had out-toeing and 2 patients had in-toeing at follow up, they had good hip scores.

LEVEL OF EVIDENCE

Level III-retrospective comparative study.

Surgical treatment of slipped capital femoral epiphysis (SCFE) by Dunn procedure modified by Ganz: a systematic review

BACKGROUND

Treatment of SCFE is still controversial, especially in moderate and severe forms. Dunn osteotomy performed with the Ganz approach became very popular in the last decade, although it is a complicated and challenging surgical procedure with a risk of AVN. The aim of our study was to analyze the current literature verifying the effectiveness of this surgical procedure, with specific attention to the incidence of AVN and other complications.

MAIN BODY

A systematic review on the subject was performed according to the PRISMA guidelines. A literature search was performed by searching all published articles about the topic in the databases. The articles were screened for the presence of the following inclusion criteria: patients affected by slipped capital femoral epiphysis (SCFE) surgically treated by Dunn osteotomy using the Ganz surgical approach. All the patients affected by pathologies other than SCFE, treated without surgery or with procedures not including a surgical hip dislocation were excluded. Based on inclusion and exclusion criteria, 23 studies were included in our systematic review. Selected articles were published from 2009 to 2021 and they included 636 overall hips. According to the selected articles, Dunn osteotomy modified by Ganz, performed by an experienced surgeon, allows for anatomical reduction of moderate or severe SCFE with a low incidence of AVN.

CONCLUSIONS

The few papers with long term follow-up, reported no progression of hip osteoarthritis, however, since the patients are adolescent at surgery, longer follow-up studies are needed to validate this statement. It is still debated if better results are obtained in stable or unstable SCFE. The indication of this procedure in mild SCFE remains controversial.

LEVEL OF EVIDENCE

3.

Is anterior subcapital shortening osteotomy a reliable and reproducible technique in the treatment of severe slipped capital femoral epiphysis?

INTRODUCTION

Proximal femoral shortening osteotomies are becoming the treatment of choice for severe slipped capital femoral epiphysis (SCFE) to reduce the risk of femoroacetabular impingement. The reported rates of complication seem reasonable, but these are single-operator series with surgeons highly experienced in this technique. The purpose of this study was to assess how surgeon experience impacted the outcomes of anterior subcapital shortening osteotomy (ASSO) in severe SCFE.

HYPOTHESIS

The hypothesis was that ASSO is a reproducible technique that is accessible to junior surgeons.

MATERIALS AND METHODS

All ASSOs performed for severe SCFE (slipangle > 40°) between 2015 and 2019 were retrospectively reviewed. All osteotomies were performed by surgeons with less than 4 years' experience (senior residents), who were trained by a senior surgeon experienced in this technique (Group 1). The incidence of femoral head avascular necrosis (AVN) and complications were analyzed and compared to a historical control cohort (Group 2).

RESULTS

A total of 62 SCFEs (37 unstable and 25 stable) were analyzed. Both groups had similar demographic data and SCFE characteristics. The mean operative times were statistically comparable in both groups. The rates of AVN in unstable SCFEs and in the overall series were comparable in both groups (18.9% vs. 13.3%, p=.55 and 12.9% vs. 9.7%, p=.6). These rates were comparable in the stable forms (4.0% vs. 5.4%; p=1). However, the preoperative MRI in Group 1 showed that 42.8% of unstable hips that developed AVN were already hypoperfused before surgery. The overall rate of complication showed no significant difference between the 2 groups (26% vs. 17%, p=.16).

DISCUSSION

Although ASSO is a technically demanding procedure, it is reliable and reproducible. The main risk factor for developing AVN remains the unstable nature of SCFE and not the surgeon's experience. It can be performed by trained junior surgeons, but not in an emergency setting, with the possibility of assistance from a more experienced surgeon.

LEVEL OF EVIDENCE

IV; retrospective case study.

Comparison between anterior cuneiform osteotomy and Dunn procedure in the surgical management of unstable severe slipped femoral epiphysis: A case-control study of 41 patients

BACKGROUND

There is little consensus on the best treatment algorithm for unstable severe slipped capital femoral epiphysis (SCFE). Subcapital osteotomy, which is one of the surgical options, is performed either anteriorly (anterior cuneiform osteotomy, CO) or laterally with trochanteric osteotomy (Dunn procedure, DP). The CO is technically easier and decreases operating time. Moreover, because the DP was the standard in our department before it was replaced by the CO, we had a series of consecutive patients. Therefore, we did a retrospective case-control study in unstable, severe SCFEs treated by CO versus DP, which is to our knowledge the first one aiming to compare: (1) postoperative complications and in particular avascular necrosis, (2) functional outcome, (3) radiologic findings.

HYPOTHESIS

CO is less or just as likely to cause avascular necrosis and has the same clinical and radiologic findings as DP.

METHODS

A total of 41 patients (24 girls, i.e. 58.5%) were included between 2005 and 2018: 23 in the CO group and 18 in the DP group. The median age was 12.9 years (range, 11.5-14.9) and the median slip angle 70̊ (range, 62.5̊-80̊) with a median follow-up of 3 years (range, 2-4). Preoperative, intraoperative, and postoperative clinical and radiologic parameters (Southwick and alpha angles, and femoral head-neck offset) were analyzed, and all complications were documented.

RESULTS

Two (8.7%) cases of avascular necrosis were reported in the CO group and 6 (33.3%) in the DP group (p=.11), with an overall rate of avascular necrosis of 19.5% (8/41). Five out of the 41 patients (12.2%) underwent a total hip arthroplasty: 1/23 (4.3%) in the CO group and 4/18 (22.2%) in the DP group (p=.16). Two (9.5%) patients in the CO group and 7 (38.9%) in the DP group developed postoperative limping before any arthroplasty was performed (p=.055). The alpha angle at follow-up (54±6.1̊ vs. 59.1±7.2̊; p=.027), Oxford hip score at follow-up (17/60 [range, 14-20] vs. 23.5 [range, 19-27]) (p=.021), operating time (132 min [range, 103-166] vs. 199.5 min [range, 142-215]) (p=.011) and intraoperative bleeding (250 mL [range, 100-350] vs. 300 mL [range, 197-450]) (p=.088) were more favorable in the CO group than in the DP group.

CONCLUSIONS

The CO has similar results to DP in the surgical management of unstable severe SCFE.

LEVEL OF EVIDENCE

III; retrospective comparative study.

Prävalenz, Biomechanik und Diagnostik femoraler Achs- und Torsionsfehler

Abweichungen der Anatomie des proximalen Femurs (Torsionspathologien, Coxa valga/vara) führen zu Veränderungen der Biomechanik des Hüftgelenks. Dies kann sich in einem femoroazetabulären Impingement (FAI), einer Mehrbelastung durch erhöhten intraartikulären Druck oder einer Fehl- oder Überbelastung der Hüftgelenkabduktoren manifestieren. Die Morphologie des Beckens, insbesondere die Version und Überdachung des Azetabulums, kann einen kompensatorischen oder verstärkenden Effekt haben und muss in die globale Beurteilung des Hüftgelenks miteinbezogen werden. Eine ausführliche klinische und radiologische Evaluation ist für eine korrekte Diagnosestellung von entscheidender Bedeutung. Die Patienten berichten meist von inguinalen, z. T. aber auch von glutealen Schmerzen. Diese sind häufig von mechanischem Charakter und können durch bestimmte Bewegungen provoziert werden. Der Bewegungsumfang der Hüfte ist beim FAI vermindert, und es zeigt sich ein positiver vorderer und/oder hinterer Impingement-Test. Torsionspathologien führen häufig zu einem veränderten Gangbild. So präsentieren sich Patienten mit erhöhter femoraler Torsion oft mit einem innenrotierten, bei verminderter Torsion mit einem außenrotierten Gangbild. Zudem zeigt sich häufig eine Abduktoreninsuffizienz. Während zur Bestimmung des Collum-Diaphysen-Winkels (CCD-Winkel) eine zentrierte Beckenübersichtsröntgenaufnahme im a.-p.-Strahlengang verwendet werden kann, sollte die Bestimmung der Torsion anhand einer Computertomographie (CT) oder Magnetresonanztomographie (MRT) von Knien und Hüftgelenk erfolgen. Von entscheidender Bedeutung ist die Angabe der verwendeten Messmethode der femoralen Torsion, da große systematische Unterschiede der Torsionswerte zwischen den verschiedenen Messmethoden bestehen.

OSTEOTOMY AT THE BASE OF FEMORAL NECK AND OSTEOPLASTY FOR THE TREAMENT OF SCFE

ABSTRACT Objective: To compare the clinical outcomes between patients with moderate and severe slipped capital femoral epiphysis (SCFE) treated with osteotomy at the base of neck and osteoplasty and with healthy individuals. Methods: Comparative cohort with 12 patients (14 hips) with moderate and severe SCFE who underwent osteotomy at the base of neck and osteoplasty between 2007 and 2014. The mean age at surgery was 13.3 ± 2.5 years and the mean follow-up was 3.8 ± 2.2 years. We assessed the level of hip pain by the visual analog scale (VAS) and anterior impingement test (AIT); the level of function using the Harris Hip Score (HHS) and 12-Item Short Form Health Survey (SF-12), the range of motion (ROM) by goniometry and Drehmann sign, and the hip muscular strength by isokinetic and Trendelenburg sign. Results: The level of pain was slightly higher in the SCFE cohort compared with healthy hips (VAS, 0.8 ± 1.4 vs 0 ± 0, 0.007; AIT, 14% vs 0%, p = 0.06; respectively). No differences were observed between the SCFE and control cohort for the functional scores (HHS, 94 ± 7 vs 100 ± 1, p = 0.135); except for ROM, with increased internal rotation (37.3º ± 9.4º vs 28.7º ± 8.2º, p < 0.001), and strength, with decreased abduction torque (75.5 ± 36.9 Nm/Kg vs 88.5 ± 27.6 Nm/Kg, p = 0.045) in the SCFE cohort. Conclusion: The osteotomy at the base of neck and the osteoplasty restored the hip motion and muscle strength, except for the abductor strength, to near normal levels, representing a viable option for the treatment of moderate and severe SCFE. Level of Evidence III, Ambidirectional Cohort Study.

Three-Dimensional Magnetic Resonance Imaging Bone Models of the Hip Joint Using Deep Learning: Dynamic Simulation of Hip Impingement for Diagnosis of Intra- and Extra-articular Hip Impingement

Background:

Dynamic 3-dimensional (3D) simulation of hip impingement enables better understanding of complex hip deformities in young adult patients with femoroacetabular impingement (FAI). Deep learning algorithms may improve magnetic resonance imaging (MRI) segmentation.

Purpose:

(1) To evaluate the accuracy of 3D models created using convolutional neural networks (CNNs) for fully automatic MRI bone segmentation of the hip joint, (2) to correlate hip range of motion (ROM) between manual and automatic segmentation, and (3) to compare location of hip impingement in 3D models created using automatic bone segmentation in patients with FAI.

Study Design:

Cohort study (diagnosis); Level of evidence, 3.

Methods:

The authors retrospectively reviewed 31 hip MRI scans from 26 symptomatic patients (mean age, 27 years) with hip pain due to FAI. All patients had matched computed tomography (CT) and MRI scans of the pelvis and the knee. CT- and MRI-based osseous 3D models of the hip joint of the same patients were compared (MRI: T1 volumetric interpolated breath-hold examination high-resolution sequence; 0.8 mm³ isovoxel). CNNs were used to develop fully automatic bone segmentation of the hip joint, and the 3D models created using this method were compared with manual segmentation of CT- and MRI-based 3D models. Impingement-free ROM and location of hip impingement were calculated using previously validated collision detection software.

Results:

The difference between the CT- and MRI-based 3D models was <1 mm, and the difference between fully automatic and manual segmentation of MRI-based 3D models was <1 mm. The correlation of automatic and manual MRI-based 3D models was excellent and significant for impingement-free ROM (r = 0.995; P < .001), flexion (r = 0.953; P < .001), and internal rotation at 90° of flexion (r = 0.982; P < .001). The correlation for impingement-free flexion between automatic MRI-based 3D models and CT-based 3D models was 0.953 (P < .001). The location of impingement was not significantly different between manual and automatic segmentation of MRI-based 3D models, and the location of extra-articular hip impingement was not different between CT- and MRI-based 3D models.

Conclusion:

CNN can potentially be used in clinical practice to provide rapid and accurate 3D MRI hip joint models for young patients. The created models can be used for simulation of impingement during diagnosis of intra- and extra-articular hip impingement to enable radiation-free and patient-specific surgical planning for hip arthroscopy and open hip preservation surgery.

Long-Term Results of Slipped Capital Femoral Epiphysis Treated with the Modified Dunn Procedure in a Colombian Cohort

Backgroud

Slipped capital femoral epiphysis (SCFE) is a severe and catastrophic disorder that affects the hips of adolescents. Many reports about surgical procedures to treat this condition have been published, but to our knowledge, there are no published results of treatment in Latin American patients. This study describes the clinical and radiological results of the modified Dunn procedure with the surgical approach described by Ganz to treat mild to severe SCFE in a cohort of Colombian pediatric patients.

Methods

We retrospectively analyzed 21 patients (22 hips) with SCFE treated with surgical dislocation of the hip from 2005 to 2017. The same pediatric orthopedic surgeon performed all operations. Clinical outcome was assessed using the range of movement and Merle d'Aubigné score, while radiological measurements and assessment included the slip angle and Tönnis score.

Results

The average duration of follow-up was 29 months (range, 12-72 months). Of all cases, 17 presented with acute-on-chronic symptoms. Preoperatively, all 22 hips were classified as poor according to the Merle d'Aubigné score. Preoperative radiological classification showed compromise grade II or III in 20 hips. Last follow-up Merle d'Aubigné score rated 17 cases as good or excellent (p < 0.05). The postoperative radiological classification was grade I or II in all 22 cases, and the Tönnis score was stage II in 3 cases and stage III in 4 cases.

Conclusions

Our results suggest that the modified Dunn osteotomy performed through the Ganz technique could be safely and effectively used to treat patients with mild to severe SCFE.

Complications of hip preserving surgery

Preoperative evaluation of the pathomorphology is crucial for surgical planning, including radiographs as the basic modality and magnetic resonance imaging (MRI) and case-based additional imaging (e.g. 3D-CT, abduction views).

Hip arthroscopy (HAS) has undergone tremendous technical advances, an immense increase in use and the indications are getting wider. The most common indications for revision arthroscopy are labral tears and residual femoroacetabular impingement (FAI).

Treatment of borderline developmental dysplastic hip is currently a subject of controversy. It is paramount to understand the underlining problem of the individual hip and distinguish instability (dysplasia) from FAI, as the appropriate treatment for unstable hips is periacetabular osteotomy (PAO) and for FAI arthroscopic impingement surgery.

PAO with a concomitant cam resection is associated with a higher survival rate compared to PAO alone for the treatment of hip dysplasia. Further, the challenge for the surgeon is the balance between over- and undercorrection.

Femoral torsion abnormalities should be evaluated and evaluation of femoral rotational osteotomy for these patients should be incorporated to the treatment plan.

Cite this article: EFORT Open Rev 2021;6:472-486. DOI: 10.1302/2058-5241.6.210019

Epiphyseal Translation as a Predictor of Avascular Necrosis in Unstable Slipped Capital Femoral Epiphysis

BACKGROUND

Physeal instability has been shown to be associated with a higher risk of avascular necrosis (AVN) in patients with slipped capital femoral epiphysis (SCFE). The purpose of this study was to identify additional preoperative factors associated with AVN in patients with unstable SCFE.

METHODS

Basic demographic information, chronicity of symptoms, and estimated duration of nonambulatory status were noted. Preoperative radiographs were used to measure the Southwick slip angle, slip severity by Wilson criteria, and epiphyseal translation. Translation was measured by 3 distinct radiographic parameters in the position demonstrating maximal displacement. Postoperative radiographs at the time of most recent follow-up were assessed for the presence of AVN. Translation measurements were tested for inter-rater reliability. Patients who developed AVN were compared with those that did not by Fisher exact test and Wilcoxon tests. Logistic regression assessed the effect of translation on the odds of developing AVN. Receiver operating characteristic curve was plotted to assess any threshold effect.

RESULTS

Fifty-one patients (55 hips) out of 310 patients (16%) treated for SCFE were considered unstable. Seventeen hips' unstable SCFE (31%) showed radiographic evidence of AVN. Slip severity by Wilson grade (P=0.009) and epiphyseal translation by all measurements (P< 0.05) were statistically significantly greater among patients who developed AVN. Superior translation had the best inter-rater reliability (intraclass correlation coefficient=0.84). Average superior translation in hips that developed AVN was 17.2 mm compared with 12.9 mm in those that did not (P<0.02). Although the receiver operating characteristic curve did not demonstrate a threshold effect for AVN, it did effectively rule out AVN in cases with <1 cm of superior translation. Age, sex, laterality, chronicity of prodromal symptoms or inability to bear weight, Southwick slip angle, and method of treatment did not vary with the occurrence of AVN.

CONCLUSIONS

Epiphyseal translation, either by Wilson Grade or measured directly, is associated with AVN in patients with an unstable SCFE.

LEVEL OF EVIDENCE

Level II-development of diagnostic criteria.

MRI-based 3D models of the hip joint enables radiation-free computer-assisted planning of periacetabular osteotomy for treatment of hip dysplasia using deep learning for automatic segmentation

Introduction

Both Hip Dysplasia(DDH) and Femoro-acetabular-Impingement(FAI) are complex three-dimensional hip pathologies causing hip pain and osteoarthritis in young patients. 3D-MRI-based models were used for radiation-free computer-assisted surgical planning. Automatic segmentation of MRI-based 3D-models are preferred because manual segmentation is time-consuming.To investigate(1) the difference and(2) the correlation for femoral head coverage(FHC) between automatic MR-based and manual CT-based 3D-models and (3) feasibility of preoperative planning in symptomatic patients with hip diseases.

Methods

We performed an IRB-approved comparative, retrospective study of 31 hips(26 symptomatic patients with hip dysplasia or FAI). 3D MRI sequences and CT scans of the hip were acquired. Preoperative MRI included axial-oblique T1 VIBE sequence(0.8 mm³ isovoxel) of the hip joint. Manual segmentation of MRI and CT scans were performed. Automatic segmentation of MRI-based 3D-models was performed using deep learning.

Results

(1)The difference between automatic and manual segmentation of MRI-based 3D hip joint models was below 1 mm(proximal femur 0.2 ± 0.1 mm and acetabulum 0.3 ± 0.5 mm). Dice coefficients of the proximal femur and the acetabulum were 98 % and 97 %, respectively. (2)The correlation for total FHC was excellent and significant(r = 0.975, p < 0.001) between automatic MRI-based and manual CT-based 3D-models. Correlation for total FHC (r = 0.979, p < 0.001) between automatic and manual MR-based 3D models was excellent.(3)Preoperative planning and simulation of periacetabular osteotomy was feasible in all patients(100 %) with hip dysplasia or acetabular retroversion.

Conclusions

Automatic segmentation of MRI-based 3D-models using deep learning is as accurate as CT-based 3D-models for patients with hip diseases of childbearing age. This allows radiation-free and patient-specific preoperative simulation and surgical planning of periacetabular osteotomy for patients with DDH.

Long-term follow-up of patients undergoing the modified Dunn procedure for slipped capital femoral epiphysis

Aims

Our retrospective analysis reports the outcome of patients operated for slipped capital femoral epiphysis using the modified Dunn procedure. Results, complications, and the need for revision surgery are compared with the recent literature.

Methods

We retrospectively evaluated 17 patients (18 hips) who underwent the modified Dunn procedure for the treatment of slipped capital femoral epiphysis. Outcome measurement included standardized scores. Clinical assessment included ambulation, leg length discrepancy, and hip mobility. Radiographically, the quality of epiphyseal reduction was evaluated using the Southwick and Alpha-angles. Avascular necrosis, heterotopic ossifications, and osteoarthritis were documented at follow-up.

Results

At a mean follow-up of more than nine years, the mean modified Harris Hip score was 88.7 points, the Hip Disability and Osteoarthritis Outcome Score (HOOS) 87.4 , the Merle d’Aubigné Score 16.5 points, and the UCLA Activity Score 8.4. One patient developed a partial avascular necrosis of the femoral head, and one patient already had an avascular necrosis at the time of delayed diagnosis. Two hips developed osteoarthritic signs at 14 and 16 years after the index operation. Six patients needed a total of nine revision surgeries. One operation was needed for postoperative hip subluxation, one for secondary displacement and implant failure, two for late femoroacetabular impingement, one for femoroacetabular impingement of the opposite hip, and four for implant removal.

Conclusion

Our series shows good results and is comparable to previous published studies. The modified Dunn procedure allows the anatomic repositioning of the slipped epiphysis. Long-term results with subjective and objective hip function are superior, avascular necrosis and development of osteoarthritis inferior to other reported treatment modalities. Nevertheless, the procedure is technically demanding and revision surgery for secondary femoroacetabular impingement and implant removal are frequent.

Cite this article: 2020;1-4:80–87.

Hip preservation

Classical indications for hip preserving surgery are: femoro-acetabular impingement (FAI) (intra- and extra-articular), hip dysplasia, slipped capital femoral epiphysis, residual deformities after Perthes disease, avascular necrosis of the femoral head.

Pre-operative evaluation of the pathomorphology is crucial for surgical planning including radiographs as the basic modality and magnetic resonance imaging (MRI) and/or computed tomography (CT) to evaluate further intra-articular lesions and osseous deformities.

Two main mechanisms of intra-articular impingement have been described:

(1) Inclusion type FAI (‘cam type’).

(2) Impaction type FAI (‘pincer type’).

Either arthroscopic or open treatment can be performed depending on the severity of deformity.

Slipped capital femoral epiphysis often results in a cam-like deformity of the hip. In acute cases a subcapital re-alignment (modified Dunn procedure) of the femoral epiphysis is an effective therapy.

Perthes disease can lead to complex femoro-acetabular deformity which predisposes to impingement with/without joint incongruency and requires a comprehensive diagnostic workup for surgical planning.

Developmental dysplasia of the hip results in a static overload of the acetabular rim and early osteoarthritis. Surgical correction by means of periacetabular osteotomy offers good long-term results.

Cite this article: EFORT Open Rev 2020;5:630-640. DOI: 10.1302/2058-5241.5.190074

Epiphyseal Angulation and Related Spatial Orientation in Slipped Capital Femoral Epiphysis: Theoretical Model and Biomechanical Explanation of Varus and Valgus Slip

The management of slipped capital femoral epiphysis (SCFE) is controversial. Surgical decision-making is based regularly on the chronicity, stability, and severity of the slip. The purpose of this study was to determine the true angulation and spatial orientation of the epiphysis in hips with SCFE and contralateral hips.

METHODS

Eighteen hips in 18 patients with SCFE were included in the analysis. Trigonometric calculations, based on angle measurements using 2 conventional radiographs in planes that are perpendicular to each other, were used to determine the angulation of the epiphysis and its orientation in space.

RESULTS

The mean absolute epiphyseal obliquity of the SCFE hips was 56.2° and the spatial orientation was 36.5°. The mean obliquity of the contralateral side was 34.0°, with a related spatial orientation of 16.8°. The maximum error can reach up to 9.9° (or 41%) when comparing the calculated angles with the angle measurements on radiographs.

CONCLUSIONS

On standard radiographs, the epiphyseal angulation in SCFE is consistently underestimated. As a consequence, the assigned classification of some patients may be 1 severity group too low, which impacts the value of traditional severity classification for surgical decision-making. The analysis of the spatial orientation of the slip with the concomitant direction of the resultant shear can partially explain varus and valgus slip in SCFE.

LEVEL OF EVIDENCE

Diagnostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

[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]

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.

Management of Slipped Capital Femoral Epiphysis: The Hawai'i Experience

Slipped capital femoral epiphysis (SCFE) is a growing problem amongst children in Hawai'i as well as throughout the world. With increasing rates of childhood obesity, SCFEs are affecting more patients at younger ages. This makes the treatment of SCFEs critical as many children with SCFEs have significant growth remaining. There are a host of treatment options based on different classification schemes which can make it difficult to determine the appropriate care for a SCFE patient. In our practice, patients are treated based on a combination of angular displacement, stability as defined by Loder, and patient age. The procedures vary from single screw in-situ fixation for a mild deformity to a modified Dunn procedure for a high-grade deformity in the skeletally immature patient. For all our open fixation methods, epiphyseal perfusion is monitored with an 18-gauge needle attached to an arterial monitor and we routinely remove fixation after physeal closure. Excellent outcomes have been noted for the modified Dunn in our practice. This article describes the algorithm used to treat SCFE in Hawai'i at a tertiary children's medical center.

Femoroacetabular Impingement Patients With Decreased Femoral Version Have Different Impingement Locations and Intra- and Extraarticular Anterior Subspine FAI on 3D-CT-Based Impingement Simulation: Implications for Hip Arthroscopy

BACKGROUND

It remains unclear whether decreased femoral version (FV) causes anterior intra- or extra-articular femoroacetabular impingement (FAI). Therefore, we evaluated symptomatic hips with decreased FV, with and without cam and pincer FAI, by using computed tomography (CT)-based virtual 3-dimensional (3D) impingement simulation and compared this group with patients with normal FV and with asymptomatic hips.

PURPOSE

To investigate (1) the osseous range of motion, (2) the osseous femoral and acetabular impingement zones, and (3) whether hip impingement is extra- or intra-articular in symptomatic hips with FAI.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

An institutional review board-approved, retrospective comparative analysis was performed on a total of 84 hips in 68 participants. Of these, 37 hips in 24 symptomatic patients with FAI had decreased FV. These hips were compared with 21 hips of 18 symptomatic patients with anterior FAI with normal FV (10°-25°) and 26 asymptomatic hips with no FAI and normal FV. All patients with FAI were symptomatic and had anterior hip pain and a positive anterior impingement test. They underwent pelvic CT scans to measure FV. Decreased FV was defined as FV less than 5°. The 37 hips with decreased FV presented both with and without cam and pincer FAI. All 84 hips were evaluated by use of CT-based 3D models and a validated 3D range of motion and impingement simulation. Asymptomatic hips were contralateral normal hips imaged in patients undergoing total hip arthroplasty.

RESULTS

Hips with FAI combined with decreased FV had a significantly (P < .001) lower mean flexion (114°± 8° vs 125°± 13°) and internal rotation (IR) at 90° of flexion (18°± 6° vs 32°± 9°, P < .001) compared with the asymptomatic control group. Symptomatic patients with FAI and normal FV had flexion of 120°± 16° and IR at 90° of flexion of 23°± 15°. In a subgroup analysis, we found a significantly (P < .001) lower IR in 90° of flexion in hips with FV less than 5° combined with mixed-type FAI compared with hips with FV less than 5° without a cam- or pincer-type deformity. The maximal acetabular impingement zone for hips with decreased FV was located at the 2-o'clock position and ranged from 1 to 3 o'clock. In hips with decreased FV, most of the impingement locations were intra-articular but 32% of hips had combined intra- and extra-articular FAI in internal rotation in 90° of flexion. During the flexion-adduction-IR test performed in 10° and 20° of adduction, extra-articular subspine FAI had significantly (P < .001) higher prevalence (68% and 84%) in hips with decreased FV compared with normal hips.

CONCLUSION

Hips with FAI and decreased FV had less flexion and internal rotation in 90° of flexion compared with the asymptomatic control group. The majority of hip impingement due to low FV was intra-articular, but one-third of samples had combined intra- and extra-articular subspine FAI. Anterior extra- and intra-articular hip impingement can be present in patients who have FAI with decreased FV. This could be important for patients undergoing hip arthroscopy.

Prevalence and diagnostic accuracy of in-toeing and out-toeing of the foot for patients with abnormal femoral torsion and femoroacetabular impingement: implications for hip arthroscopy and femoral derotation osteotomy

AIMS

Abnormal femoral torsion (FT) is increasingly recognized as an additional cause for femoroacetabular impingement (FAI). It is unknown if in-toeing of the foot is a specific diagnostic sign for increased FT in patients with symptomatic FAI. The aims of this study were to determine: 1) the prevalence and diagnostic accuracy of in-toeing to detect increased FT; 2) if foot progression angle (FPA) and tibial torsion (TT) are different among patients with abnormal FT; and 3) if FPA correlates with FT.

PATIENTS AND METHODS

A retrospective, institutional review board (IRB)-approved, controlled study of 85 symptomatic patients (148 hips) with FAI or hip dysplasia was performed in the gait laboratory. All patients had a measurement of FT (pelvic CT scan), TT (CT scan), and FPA (optical motion capture system). We allocated all patients to three groups with decreased FT (< 10°, 37 hips), increased FT (> 25°, 61 hips), and normal FT (10° to 25°, 50 hips). Cluster analysis was performed.

RESULTS

We found a specificity of 99%, positive predictive value (PPV) of 93%, and sensitivity of 23% for in-toeing (FPA < 0°) to detect increased FT > 25°. Most of the hips with normal or decreased FT had no in-toeing (false-positive rate of 1%). Patients with increased FT had significantly (p < 0.001) more in-toeing than patients with decreased FT. The majority of the patients (77%) with increased FT walk with a normal foot position. The correlation between FPA and FT was significant (r = 0.404, p < 0.001). Five cluster groups were identified.

CONCLUSION

In-toeing has a high specificity and high PPV to detect increased FT, but increased FT can be missed because of the low sensitivity and high false-negative rate. These results can be used for diagnosis of abnormal FT in patients with FAI or hip dysplasia undergoing hip arthroscopy or femoral derotation osteotomy. However, most of the patients with increased FT walk with a normal foot position. This can lead to underestimation or misdiagnosis of abnormal FT. We recommend measuring FT with CT/MRI scans in all patients with FAI. Cite this article: Bone Joint J 2019;101-B:1218-1229.

Patient-Specific 3-D Magnetic Resonance Imaging-Based Dynamic Simulation of Hip Impingement and Range of Motion Can Replace 3-D Computed Tomography-Based Simulation for Patients With Femoroacetabular Impingement: Implications for Planning Open Hip Preservation Surgery and Hip Arthroscopy

BACKGROUND

Femoroacetabular impingement (FAI) is a complex 3-dimensional (3D) hip abnormality that can cause hip pain and osteoarthritis in young and active patients of childbearing age. Imaging is static and based on 2-dimensional radiographs or computed tomography (CT) scans. Recently, CT-based 3D impingement simulation was introduced for patient-specific assessments of hip deformities, whereas magnetic resonance imaging (MRI) offers a radiation-free alternative for surgical planning before hip arthroscopic surgery.

PURPOSE

To (1) investigate the difference between 3D models of the hip, (2) correlate the location of hip impingement and range of motion (ROM), and (3) correlate diagnostic parameters while comparing CT- and MRI-based osseous 3D models of the hip in symptomatic patients with FAI.

STUDY DESIGN

Cohort study (Diagnosis); Level of evidence, 2.

METHODS

The authors performed an institutional review board-approved comparative and retrospective study of 31 hips in 26 symptomatic patients with FAI. We compared CT- and MRI-based osseous 3D models of the hip in the same patients. 3D CT scans (slice thickness, 1 mm) of the entire pelvis and the distal femoral condyles were obtained. Preoperative MRI of the hip was performed including an axial-oblique T1 VIBE sequence (slice thickness, 1 mm) and 2 axial anisotropic (1.2 × 1.2 × 1 mm) T1 VIBE Dixon sequences of the entire pelvis and the distal femoral condyles. Threshold-based semiautomatic reconstruction of 3D models was performed using commercial software. CT- and MRI-based 3D models were compared with specifically developed software.

RESULTS

(1) The difference between MRI- and CT-based 3D models was less than 1 mm for the proximal femur and the acetabulum (median surface distance, 0.4 ± 0.1 mm and 0.4 ± 0.2 mm, respectively). (2) The correlation for ROM values was excellent (r = 0.99, P < .001) between CT and MRI. The mean absolute difference for flexion and extension was 1.9°± 1.5° and 2.6°± 1.9°, respectively. The location of impingement did not differ between CT- and MRI-based 3D ROM analysis in all 12 of 12 acetabular and 11 of 12 femoral clock-face positions. (3) The correlation for 6 diagnostic parameters was excellent (r = 0.98, P < .001) between CT and MRI. The mean absolute difference for inclination and anteversion was 2.0°± 1.8° and 1.0°± 0.8°, respectively.

CONCLUSION

Patient-specific and radiation-free MRI-based dynamic 3D simulation of hip impingement and ROM can replace CT-based 3D simulation for patients with FAI of childbearing age. On the basis of these excellent results, we intend to change our clinical practice, and we will use MRI-based 3D models for future clinical practice instead of CT-based 3D models. This allows radiation-free and patient-specific preoperative 3D impingement simulation for surgical planning and simulation of open hip preservation surgery and hip arthroscopic surgery.

[The modified Dunn procedure to treat severe slipped capital femoral epiphysis]

The modified Dunn procedure enables restoration of the proximal femoral anatomy and normal hip function in patients with slipped capital femoral epiphysis (SCFE). Surgery is indicated in severe SCFE and in hips with a moderate slip angle and impaired function. To prevent further dislocation of the femoral head, the authors recommend non-weightbearing until surgery, since an accurate evaluation of slip stability is not possible in the clinical setting. Only a well-trained orthopedic surgeon with a high level of expertise in hip preservation surgery should perform this procedure. Precise knowledge of the vascular anatomy of the proximal femur is essential to perform successful surgery with low rates of complications such as avascular necrosis of the femoral head. Surgical hip dislocation with osteotomy of the greater trochanter is the approach used. After arthrotomy, stability of the physis is checked. To prevent rupture of the retinacular vessels in hips with an unstable physis, these heads are prophylactically pinned before dislocation out of the socket. Blood supply to the femoral head as well as intraarticular damage can be judged in the dislocated position of the femoral head. The retinacular flap preserves epiphyseal perfusion while the femoral head is dislocated from the femoral neck. Resection of posteromedial callous formation from the femoral neck as well as removal of the remaining physis from the femoral head prevent stress on the retinacular vessels after reduction of the femoral head (epiphysis) on the neck.

Natural History of Slipped Capital Femoral Epiphysis

BACKGROUND

Slipped capital femoral epiphysis (SCFE) occurs at a rate of 1 in 10,000 to 20,000 children.

METHODS

A PubMed search was undertaken to evaluate recent SCFE literature. A convenience sample of articles were selected and summarized.

RESULTS

Most slips appear well tolerated long-term with ∼5% resulting in total hip arthroplasty (THA) at 20-year follow-up. Classic data reveals poor outcomes following closed reduction for treatment of SCFE. Improvements in intraoperative fluoroscopy and avoidance of pin penetration have reduced the rates of chondrolysis. Unfortunately, avascular necrosis remains a known risk in patients, occurring in 15% to 50% of patients following acute, unstable slips. This is the most common cause of THA in patients with SCFE. Rate of THA due to degenerative arthritis secondary to SCFE is more difficult to determine and occurs at a later age. Although realignment procedures to address anatomic abnormalities from SCFE have increased in popularity, it is unclear if this prevents degenerative arthritis and subsequently reduces the rate of THA. SCFE patients face an increased risk of disability and death due to their underlying medical comorbidities. Interventions for weight loss, blood pressure management, and lifestyle adjustments should be considered at the time of SCFE diagnosis.

CONCLUSIONS

SCFE remains a challenging and common condition for pediatric orthopedists. Although innovative techniques have been proposed, long-term outcome data still supports in situ pinning for stable slips, and in situ pinning with capsular decompression for unstable slips to minimize the risk of avascular necrosis.

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.

What Is the Prevalence of Cam Deformity After Prophylactic Pinning of the Contralateral Asymptomatic Hip in Unilateral Slipped Capital Femoral Epiphysis? A 10-year Minimum Followup Study

BACKGROUND

Prophylactic pinning of the asymptomatic and normal-appearing contralateral hip in patients with unilateral slipped capital femoral epiphysis (SCFE) remains controversial. Understanding the minimal 10-year clinical, functional, and radiographic outcomes of the contralateral asymptomatic hip in unilateral SCFE may be helpful in the decision regarding whether the benefits associated with potentially preventing a SCFE are outweighed by the risk of additional surgery.

QUESTIONS/PURPOSES

Among patients with SCFE treated with prophylactic pinning of the asymptomatic and contralateral hip, we sought (1) to determine the complications and reoperations; (2) to evaluate the development of cam deformities and the frequency and severity of osteoarthritis progression; and (3) to characterize hip pain and function as measured by the Harris hip score (HHS) and the Hip Disability and Osteoarthritis Outcome Score (HOOS) at minimal 10-year followup.

METHODS

Between 1998 and 2005 all patients with SCFE seen at our institution were treated with the modified Dunn procedure and all were offered prophylactic pinning of the contralateral asymptomatic hip. Of the 41 patients who underwent the unilateral modified Dunn procedure and who had an asymptomatic contralateral hip, 37 patients (90%) underwent pinning of that contralateral hip. Of those, 33 patients (80%) were available for clinical and radiographic evaluation for this retrospective study at a minimum of 10 years (mean followup 12 ± 2 years) after surgery. Three patients of the 37 patients only had 10-year clinical followup, including questionnaires sent by mail and telephone, because they refused further radiographic followup and one patient was lost to followup. The group included 19 males and 17 females whose age at surgery was a mean of 13 ± 2 years. Medical charts were reviewed and patients were asked about complications and additional surgical procedures. Most recent postoperative radiographs were evaluated for measurement of the alpha angle, head-neck offset, epiphysis orientation, and osteoarthritis grading according to Tönnis classification and minimum joint space width. The presence of a cam deformity was defined by an alpha angle measurement > 60° on the AP radiograph and/or > 55° on the lateral radiograph. Hip function and pain were assessed by the HHS and HOOS outcome measures.

RESULTS

No complications with prophylactic in situ pinning were recorded. Four of 36 (11%) patients underwent subsequent surgical treatment for cam-type femoroacetabular impingement (FAI), and hardware removal was performed in four hips (11%). The mean alpha angle was 53° ± 8° on the AP radiograph and 49° ± 8° on the lateral view at followup. In total, 10 of 33 hips (30%) had a cam morphology at the femoral head-neck junction and four (12%) were symptomatic and underwent FAI surgery. Six of 33 patients (18%) developed an asymptomatic cam morphology at the femoral head-neck junction; in three of 33 hips (9%), the cam deformity instead of lesion were visible only on the lateral projection, and 9% were visible on both the AP and lateral projections. The preoperative offset of the femoral head-neck junction was 10 ± 3 mm on the AP view and 11 ± 4 mm on the lateral view. At followup, the AP offset was 7 ± 3 mm and the lateral offset was 6 ± 3 mm, and on the lateral view, the offset was < 10 mm in eight hips (22%). No patient had radiographic signs of hip osteoarthritis (Tönnis Grade 0). The mean minimum joint space width was 4 ± 0.4 mm. The mean HHS for the 32 patients who did not undergo subsequent surgery was 97 ± 5 at latest followup. The mean postoperative HOOS was 94 ± 8 for the 32 patients at latest followup.

CONCLUSIONS

At a minimum followup of 10 years after prophylactic pinning of a contralateral asymptomatic hip, most patients achieve excellent hip scores; however, a substantial proportion will develop a symptomatic cam deformity despite prophylactic pinning. No patient had signs of osteoarthritis at a minimum of 10 years, but almost one-third of the patients who underwent prophylactic pinning developed a cam deformity.

LEVEL OF EVIDENCE

Level IV, therapeutic study.

Patients with severe slipped capital femoral epiphysis treated by the modified Dunn procedure have low rates of avascular necrosis, good outcomes, and little osteoarthritis at long-term follow-up

AIMS

The modified Dunn procedure has the potential to restore the anatomy in hips with severe slipped capital femoral epiphyses (SCFE). However, there is a risk of developing avascular necrosis of the femoral head (AVN). In this paper, we report on clinical outcome, radiological outcome, AVN rate and complications, and the cumulative survivorship at long-term follow-up in patients undergoing the modified Dunn procedure for severe SCFE.

PATIENTS AND METHODS

We performed a retrospective analysis involving 46 hips in 46 patients treated with a modified Dunn procedure for severe SCFE (slip angle > 60°) between 1999 and 2016. At nine-year-follow-up, 40 hips were available for clinical and radiological examination. Mean preoperative age was 13 years, and 14 hips (30%) presented with unstable slips. Mean preoperative slip angle was 64°. Kaplan-Meier survivorship was calculated.

RESULTS

At the latest follow-up, the mean Merle d'Aubigné and Postel score was 17 points (14 to 18), mean modified Harris Hip Score was 94 points (66 to 100), and mean Hip Disability and Osteoarthritis Outcome Score was 91 points (67 to 100). Postoperative slip angle was 7° (1° to 16°). One hip (2%) had progression of osteoarthritis (OA). Two hips (5%) developed AVN of the femoral head and required further surgery. Three other hips (7%) underwent implant revision due to screw breakage or change of wires. Cumulative survivorship was 86% at ten-year follow-up.

CONCLUSION

The modified Dunn procedure for severe SCFE resulted in a low rate of AVN, low risk of progression to OA, and high functional scores at long-term follow-up. The slip deformities were mainly corrected but secondary impingement deformities can develop in some hips and may require further surgical treatment. Cite this article: Bone Joint J 2019;101-B:403-414.

Slipped capital femoral epiphysis: current management strategies

In orthopedic literature, there is little consensus regarding the best management of slipped capital femoral epiphysis (SCFE). Controversies and disparate trends derive from differences in clinical presentation, various classifications, and a variety of surgical procedures that have been described. Currently, there are no evidence-based recommendations. Surgical procedures vary, and they can be divided into fixation in situ, compensatory osteotomies, and direct corrections of the deformity at the head–neck junction. The first and second group of procedures have so far not gained optimal control over the risk of avascular necrosis or cannot achieve an anatomically aligned epiphysis with normal blood supply. On the other hand, the third technique can achieve this target and prevent residual deformity and the development of early hip arthritis, but it is not widely accepted, because of its surgical complexity. The purpose of this work is to present an overview of current knowledge and provide an orientation on clinical and surgical management of the patient suffering from SCFE.

Reliability of the Modified Clavien-Dindo-Sink Complication Classification System in Pediatric Orthopaedic Surgery

Background

There is no standardized complication classification system that has been evaluated for use in pediatric or general orthopaedic surgery. Instead, subjective terms such as major and minor are commonly used. The Clavien-Dindo-Sink complication classification system has demonstrated high interrater and intrarater reliability for hip-preservation surgery and has increasingly been used within other orthopaedic subspecialties. This classification system is based on the magnitude of treatment required and the potential for each complication to result in long-term morbidity. The purpose of the current study was to modify the Clavien-Dindo-Sink system for application to all orthopaedic procedures (including those involving the spine and the upper and lower extremity) and to determine interrater and intrarater reliability of this modified system in pediatric orthopaedic surgery cases.

Methods

The Clavien-Dindo-Sink complication classification system was modified for use with general orthopaedic procedures. Forty-five pediatric orthopaedic surgical scenarios were presented to 7 local fellowship-trained pediatric orthopaedic surgeons at 1 center to test internal reliability, and 48 scenarios were then presented to 15 pediatric orthopaedic surgeons across the United States and Canada to test external reliability. Surgeons were trained to use the system and graded the scenarios in a random order on 2 occasions. Fleiss and Cohen kappa (κ) statistics were used to determine interrater and intrarater reliabilities, respectively.

Results

The Fleiss κ value for interrater reliability (and standard error) was 0.76 ± 0.01 (p < 0.0001) and 0.74 ± 0.01 (p < 0.0001) for the internal and external groups, respectively. For each grade, interrater reliability was good to excellent for both groups, with an overall range of 0.53 for Grade I to 1 for Grade V. The Cohen κ value for intrarater reliability was excellent for both groups, ranging from 0.83 (95% confidence interval [CI], 0.71 to 0.95) to 0.98 (95% CI, 0.94 to 1.00) for the internal test group and from 0.83 (95% CI, 0.73 to 0.93) to 0.99 (95% CI, 0.97 to 1.00) for the external test group.

Conclusions

The modified Clavien-Dindo-Sink classification system has good interrater and excellent intrarater reliability for the evaluation of complications following pediatric orthopaedic upper extremity, lower extremity, and spine surgery. Adoption of this reproducible, reliable system as a standard of reporting complications in pediatric orthopaedic surgery, and other orthopaedic subspecialties, could be a valuable tool for improving surgical practices and patient outcomes.

Comparison between modified Dunn procedure and in situ fixation for severe stable slipped capital femoral epiphysis

Background and purpose - The best treatment option for severe slipped capital femoral epiphysis (SCFE) is still controversial. We compared clinical and radiographic outcomes of modified Dunn procedure (D) and in situ fixation (S) in severe SCFE. Patients and methods - We retrospectively compared D and S, used for severe stable SCFE (posterior sloping angle (PSA) > 50°) in 29 patients (15 D; 14 S). Propensity analysis and inverse probability of treatment weights (IPTW) to adjust for baseline differences were performed. Patients were followed for 2-7 years. Results - Avascular necrosis (AVN) occurred in 3 patients out of 15, after D, causing conversion to total hip replacement (THR) in 2 cases. In S, 1 hip developed chondrolysis, requiring THR 3 years after surgery. 3 symptomatic femoroacetabular impingements (FAI) occurred after S, requiring corrective osteotomy in 1 hip, and osteochondroplasty in another case. The risk of early re-operation was similar between the groups. The slippage was corrected more accurately and reliably by D. The Nonarthritic Hip Score was similar between groups, after adjusting for preoperative and postoperative variables. Interpretation - Although D was superior to S in restoring the proximal femoral anatomy, without increasing the risk of early re-operation, some concern remains regarding the potential risk of AVN in group D.

Surgical treatment of femoroacetabular impingement after slipped capital femoral epiphysis

PURPOSE OF REVIEW

Femoroacetabular impingement (FAI) post slipped capital femoral epiphysis (SCFE) may lead to degenerative changes on the hip. We have reviewed the current procedures in the literature, aiming to correct the SCFE to prevent FAI and the ones that treat FAI post SCFE.

RECENT FINDINGS

The trends of managing moderated or severe SCFE is to correct the displacement by reduction and fixation with articular hematoma decompression in unstable hips and Dunn modified procedure even for unstable and stable situations. However, after FAI is settled, the options are osteochondroplasty by arthroscopy or surgical hip dislocation, associated or not to subtrocanteric osteotomy.

SUMMARY

Femoroacetabular impingement may occur in mild slips and certainly occur in cases of moderate and severe slips. The initial management depends on the severity and the stability of the slip.The modified Dunn procedure is a good option for the treatment of unstable SCFEs. Gentle closed reduction with capsulotomy (Parsch) may be considered whenever the surgeon is not comfortable with the modified Dunn procedure.Hips with open physis and stable moderate or severe SCFE, the modified Dunn procedure can be indicated. Cases with closed physis are managed with intertrochanteric osteotomy combined with osteoplasty.In the presence of symptomatic FAI secondary to SCFE, one should consider arthroscopic osteoplasty or surgical hip dislocation (with or without osteotomies) as treatment options.

The modified Dunn procedure for slipped capital femoral epiphysis: the Bernese experience

PURPOSE

Based on previous investigations on the vascular blood supply to the femoral head, a technique for anatomical reduction after slipped capital femoral epiphysis was developed. This technique is a modification of the original technique by Dunn using a retinacular soft-tissue flap. This allows the visual control of the epiphyseal vascular blood supply. We report the experience at the inventor's institution with a critical discussion of the available literature.

METHODS

Using a trochanteric osteotomy for surgical dislocation of the hip, a retinacular soft tissue flap is created containing the deep branch of the medial femoral circumflex artery, the external rotators and the capsule. The femoral epiphysis can be mobilised safely and reduced on the femoral neck after resection of the almost constantly present reactive metaphyseal callus.

RESULTS

In our institution, the rate of avascular necrosis with 2% is comparably low to Dunn's original results. It is only present in cases where no bleeding was already evident before reduction of the epiphysis. The ten-year long-term results are favorable in these cases with a good functional result and only little progression of osteoarthritis. However, other authors have reported higher rates of avascular necrosis up to 24% in their initial experience.

CONCLUSIONS

In experienced hands using the correct meticulous surgical technique, the results are favorable regarding the rates of avascular necrosis, the functional outcome and the development of radiographic osteoarthritis - even in acute and severe cases. Avascular necrosis is rare but can be observed if there is no evidence of intra-operative femoral head perfusion before and after reduction of the epiphysis.