Clinical Orthopaedics and Related Research ®

A Publication of The Association of Bone and Joint Surgeons ®

Symposium: Femoroacetabular Impingement: Current Status of Diagnosis and Treatment 23 articles


Capital Realignment for Moderate and Severe SCFE Using a Modified Dunn Procedure

Kai Ziebarth MD, Christoph Zilkens MD, Samantha Spencer MD, Michael Leunig MD, Reinhold Ganz MD, Young-Jo Kim MD, PhD Moderate to severe slipped capital femoral epiphysis leads to premature osteoarthritis resulting from femoroacetabular impingement. We believe surgical correction at the site of deformity through capital reorientation is the best procedure to fully correct the deformity but has traditionally been associated with high rates of osteonecrosis. We describe a modified capital reorientation procedure performed through a surgical dislocation approach. We followed 40 patients for a minimum of 1 year and 3 years from two institutions. No patient developed osteonecrosis or chondrolysis. Slip angle was corrected to 4° to 8° and the mean alpha angle after correction was 40.6°. Articular cartilage damage, full-thickness loss, and delamination were observed at the time of surgery, especially in the stable slips. This technique appears to have an acceptable complication rate and appears reproducible for full correction of moderate to severe slipped capital femoral epiphyses with open physes.,[object Object]

Acetabular Morphology: Implications for Joint-preserving Surgery

Werner Köhnlein MD, Reinhold Ganz MD, Franco M. Impellizzeri PhD, Michael Leunig MD Appropriate anatomic concepts for surgery to treat femoroacetabular impingement require a precise appreciation of the native acetabular anatomy. We therefore determined (1) the spatial acetabular rim profile, (2) the topography of the articular lunate surface, and (3) the 3-D relationships of the acetabular opening plane comparing 66 bony acetabula from 33 pelves in female and male pelves. The acetabular rim profile had a constant and regular wave-like outline without gender differences. Three prominences anterosuperiorly, anteroinferiorly and posteroinferiorly extended just above hemispheric level. Two depressions were below hemispheric level, of 9° at the anterior wall and of 21° along the posterosuperior wall. In 94% of all acetabula, the deepest extent of the articular surface was within 30° of the anterosuperior acetabular sector. In 99% of men and in 91% of women, the depth of the articular surface was at least 55° along almost half of the upper acetabular cup. The articular surface was smaller in women than in men. The acetabular opening plane was orientated in 21° ± 5° for version, 48° ± 4° for inclination and 19° ± 6° for acetabular tilt with no gender differences. We defined tilt as forward rotation of the entire acetabular cup around its central axis; because of interindividual variability of acetabular tilt, descriptions of acetabular lesions during surgery, CT scanning and MRI should be defined and recorded in relation to the acetabular notch. Acetabular tilt and pelvic tilt should be separately identified. We believe this information important for surgeons performing rim trimming in FAI surgery or performing acetabular osteotomies.

Clinical Presentation of Patients with Symptomatic Anterior Hip Impingement

John C. Clohisy MD, Evan R. Knaus DO, Devyani M. Hunt MD, John M. Lesher MD, Marcie Harris-Hayes PT, Heidi Prather DO Femoroacetabular impingement (FAI) is considered a cause of labrochondral disease and secondary osteoarthritis. Nevertheless, the clinical syndrome associated with FAI is not fully characterized. We determined the clinical history, functional status, activity status, and physical examination findings that characterize FAI. We prospectively evaluated 51 patients (52 hips) with symptomatic FAI. Evaluation of the clinical history, physical exam, and previous treatments was performed. Patients completed demographic and validated hip questionnaires (Baecke et al., SF-12, Modified Harris hip, and UCLA activity score). The average patient age was 35 years and 57% were male. Symptom onset was commonly insidious (65%) and activity-related. Pain occurred predominantly in the groin (83%). The mean time from symptom onset to definitive diagnosis was 3.1 years. Patients were evaluated by an average 4.2 healthcare providers prior to diagnosis and inaccurate diagnoses were common. Thirteen percent had unsuccessful surgery at another anatomic site. On exam, 88% of the hips were painful with the anterior impingement test. Hip flexion and internal rotation in flexion were limited to an average 97° and 9°, respectively. The patients were relatively active, yet demonstrated restrictions of function and overall health. These data may facilitate diagnosis of this disorder.,[object Object]

Does Trochanteric Step Osteotomy Provide Greater Stability Than Classic Slide Osteotomy? A Preliminary Study

Ralf Schoeniger MD, Amy E. LaFrance MASc, Thomas R. Oxland PhD, Reinhold Ganz MD, Michael Leunig MD The use of a trochanteric slide osteotomy needs a partial weightbearing period to allow safe healing of the osteotomy. We compared the initial rigidity of fixation of the trochanteric slide osteotomy with that of a newly developed technique, the trochanteric step osteotomy. The slide and step osteotomies were tested on six bilateral pairs of cadaveric femora with cyclic shear load of constant amplitude for 100 cycles in both a superior direction to represent standing and 60° of hip flexion to represent a squat stance. Translational and rotational migration and cyclic amplitude were measured with an optoelectronic camera system. During superior loading, translational migration of the slide osteotomy was greater than for the step osteotomy (slide median, 1.7 mm; step median, 0.3 mm), but rotational migration was not (slide median, 1.9°; step median, 0.2°). Translational amplitude was greater for the slide osteotomy in the superior direction (median slide, 0.3 mm; median step, 0.16 mm), but not in rotational amplitude. Similar trends in migration and amplitude were observed for the squat loading configuration. The data suggest the trochanteric step osteotomy is a more stable construct than the commonly performed slide osteotomy.

Bone Scintigraphy in Femoroacetabular Impingement: A Preliminary Report

Wadih Y. Matar MD, MSc, FRCSC, Olivier May MD, MSc, François Raymond MD, FRCSC, Paul E. Beaulé MD, FRCSC Femoroacetabular impingement (FAI) has recently been recognized as a cause of hip pain, labral tears, and cartilage damage in young adults. We determined the sensitivity and specificity of bone scans in diagnosing FAI and describe its findings on nuclear imaging. We prospectively followed 25 patients with hip pain (four bilateral) of greater than 6 months’ duration and a positive impingement sign (IS). All patients had plain radiographs and a three-phase bone scan followed by single-photon emission computed topographic (SPECT) images of both hips. We presumed patients had FAI if they had all three of the following findings: hip pain, positive IS, and diagnostic radiographs. Forty-six of the 50 hips had bony abnormalities on radiographs and 26 hips were diagnosed with FAI according to our criteria. Twenty-two of these 26 hips showed an increased uptake on SPECT representing true-positives. There were four false-positives, nine false-negatives, and 15 true-negatives. Sensitivity of bone SPECT was 84.7%, specificity 62.5%, positive predictive value 71%, and negative predictive value 78.9%. Focal uptake was localized to the superolateral acetabular rim and/or anterolateral femoral head-neck junction consistent with the reported intra-articular cartilage hip damage seen in FAI.,[object Object]

Arthroscopic Femoroplasty in the Management of Cam-type Femoroacetabular Impingement

J. W. Thomas Byrd MD, Kay S. Jones MSN, RN Cam-type femoroacetabular impingement is a recognized cause of intraarticular pathology and secondary osteoarthritis in young adults. Arthroscopy is reportedly useful to treat selected hip abnormalities and has been proposed as a method of correcting underlying impingement. We report the outcomes of arthroscopic management of cam-type femoroacetabular impingement. We prospectively assessed all 200 patients (207 hips) who underwent arthroscopic correction of cam impingement from December 2003 to October 2007, using a modified Harris hip score. The minimum followup was 12 months (mean, 16 months; range, 12–24 months); no patients were lost to followup. The average age was 33 years with 138 men and 62 women. One hundred and fifty-eight patients (163 hips) underwent correction of cam impingement (femoroplasty) alone while 42 patients (44 hips) underwent concomitant correction of pincer impingement. The average increase in Harris hip score was 20 points; 0.5% converted to THA. We had a 1.5% complication rate. The short-term outcomes of arthroscopic treatment of cam-type femoroacetabular impingement are comparable to published reports for open methods with the advantage of a less invasive approach.,[object Object]

Femoroacetabular Impingement Treatment Using Arthroscopy and Anterior Approach

Frédéric Laude MD, Elhadi Sariali MD, Alexis Nogier MD Femoroacetabular impingement (FAI) has been identified as a common cause of hip pain in young adults. However, treatment is not well standardized. We retrospectively reviewed 97 patients (100 hips) who underwent osteochondroplasty of the femoral head-neck for FAI using a mini-open anterior Hueter approach with arthroscopic assistance. The mean age of the patients was 33.4 years. The labrum was refixed in 40 hips, partially excised in 39 cases, completely excised in 14 cases, and left intact in seven. Six patients were lost to followup, leaving 91 (94 hips) with a minimum followup of 28.6 months (mean, 58.3 months; range, 28.6–104.4 months). We assessed patients clinically using the nonarthritic hip score (NAHS). One patient had a femoral neck fracture 3 weeks postoperatively. At the last followup, the mean NAHS score increased by 29.1 points (54.8 ± 12 preoperatively to 83.9 ± 16 points at last followup). Eleven hips developed osteoarthritis and subsequently had total hip arthroplasty. The best results were obtained in patients younger than 40 years old with a 0 Tönnis grade. Refixation of the labrum did not correlate with a higher NAHS score (87 ± 11 with refixation versus 82 ± 19 points without) at the last followup. The technique for FAI treatment allowed direct visualization of the anterior femoral head-neck junction while avoiding surgical dislocation, had a low complication rate, and improved functional scores.,[object Object]

Groin Pain after Open FAI Surgery: The Role of Intraarticular Adhesions

Martin Beck MD Femoroacetabular impingement (FAI) is an established cause of osteoarthrosis of the hip. Surgery is intended to remove the cause of impingement with hip dislocation and resection of osseous prominences of the acetabular rim and of the femoral head-neck junction. Using the Merle d’Aubigné score and qualitative categories, recent studies suggest good to excellent outcomes in 75% to 80% of patients after open surgery with dislocation of the femoral head. Unsatisfactory outcome is mainly related to pain, located either in the area of the greater trochanter or in the groin. There are several reasons for persisting groin pain. Joint degeneration with joint space narrowing and/or osteophyte formation, insufficient correction of the acetabula, and femoral pathology are known factors for unsatisfactory outcome. Recently, intraarticular adhesions between the femoral neck and joint capsule have been identified as an additional cause of postoperative groin pain. The adhesions form between the joint capsule and the resected area on the femoral neck and may lead to soft tissue impingement. MR-arthrography is used for diagnosis and the adhesions can be treated successfully by arthroscopy. While arthroscopic resection improves outcome it is technically demanding. Avoiding the formation of adhesions is important and is perhaps best accomplished by passive motion exercises after the initial surgery.,[object Object]

Stepped Osteotomy of the Trochanter for Stable, Anatomic Refixation

Johannes D. Bastian MD, Alexandra T. Wolf MD, Tobias F. Wyss MD, Hubert P. Nötzli MD Refixation of a trochanteric osteotomy carries a high complication rate. To enhance stability and facilitate anatomic reduction of the trochanteric fragment, we have introduced a stepped osteotomy. Between April 2006 and June 2007, we performed surgical hip dislocations using the modified trochanteric osteotomy combined with a relatively aggressive rehabilitation program. Full weightbearing was allowed at a mean of 42 days (range, 33–54 days). The minimum followup was 8 months (median, 13 months; range, 8–24 months). Postoperative radiographs were assessed prospectively for consolidation or the appearance of malreduction/nonunion/malunion of the osteotomy and heterotopic ossification. In 110 of 113 hips, the trochanteric osteotomy healed in the anatomic position. Two patients had a trochanteric delayed union with loss of anatomic position, and one additional patient underwent revision surgery for a pseudarthrosis and cranial migration of the trochanteric fragment. All three complications related to healing occurred in the first 60 patients when the step height was 3 to 4 mm. After increasing the step heights to 6 mm, we observed no healing complications. Despite more aggressive postoperative mobilization, the incidence of malunion or nonunion related to the new stepped osteotomy is low and approaches zero for steps of 6 mm. It is now our technique of choice.,[object Object]

Femoroacetabular Impingement: Do Outcomes Reliably Improve with Surgical Dislocations?

Matt L. Graves, Jeff W. Mast Femoroacetabular impingement is a motion-based concept of conflict that occurs secondary to morphologic abnormalities of the proximal femur and/or acetabulum. Creating impingement-free motion through restoration of normal morphology serves as the goal of joint-preserving procedures. We retrospectively reviewed the short-term functional and radiographic outcomes of 46 patients (48 hips) with femoroacetabular impingement treated with a surgical dislocation and restoration of offset. The average Merle D’Aubigné-Postel score improved from a preoperative of 13 (range, 7–16 ± 1.7) to a postoperative score of 16.8 (range, 12–18 ± 1.3). Creating impingement-free motion via a surgical dislocation improves symptoms in patients with limited radiographic signs of arthritis who are experiencing impingement-related hip pain.,[object Object]

The Concept of Femoroacetabular Impingement: Current Status and Future Perspectives

Michael Leunig MD, Paul E. Beaulé MD, Reinhold Ganz MD Femoroacetabular impingement (FAI) is a recently proposed mechanism causing abnormal contact stresses and potential joint damage around the hip. In the majority of cases, a bony deformity or spatial malorientation of the femoral head or head/neck junction, acetabulum, or both cause FAI. Supraphysiologic motion or high impact might cause FAI even with very mild bony alterations. FAI became of interest to the medical field when (1) evidence began to emerge suggesting that FAI may initiate osteoarthritis of the hip and when (2) adolescents and active adults with groin pain and imaging evidence of FAI were successfully treated addressing the causes of FAI. With an increased recognition and acceptance of FAI as a damage mechanism of the hip, defined standards of assessment and treatment need to be developed and established to provide high accuracy and precision in diagnosis. Early recognition of FAI followed by subsequent behavioral modification (profession, sports, etc) or even surgery may reduce the rate of OA due to FAI.

Labral Reconstruction Using the Ligamentum Teres Capitis: Report of a New Technique

Rafael J. Sierra MD, Robert T. Trousdale MD We have used the ligamentum teres capitis to reconstruct the deficient or absent labrum in five patients with femoroacetabular impingement at the time of surgical hip dislocation. Two had a deficient labrum overlying a sectorial retroverted acetabulum causing pincer-type impingement. Three patients had the labrum previously resected arthroscopically. The minimum followup from surgery was 5 months (average, 10 months; range, 5–20 months). There were no intraoperative or postoperative complications related to the reconstruction. All patients had improvement in their clinical function and one patient underwent total hip arthroplasty at last followup for unresolved pain without radiographic progression of arthritis. Reconstruction of the labrum in patients with deficient or resected labrums at the time of surgical hip dislocation provides the theoretical advantage of sealing and stabilizing the hip joint, restoring the fluid layer which could potentially prevent continued cartilage degeneration.,[object Object]

Comparison of MRI Alpha Angle Measurement Planes in Femoroacetabular Impingement

Kawan S. Rakhra MD, FRCPC, Adnan M. Sheikh MD, David Allen MD, FRCSC, Paul E. Beaulé MD, FRCSC Insufficient femoral head-neck offset is common in femoroacetabular impingement (FAI) and reflected by the alpha angle, a validated measurement for quantifying this anatomic deformity in patients with FAI. We compared the alpha angle determined on magnetic resonance imaging (MRI) oblique axial plane images with the maximal alpha angle value obtained using radial images. The MRIs of 41 subjects with clinically suspected FAI were reviewed and alpha angle measurements were performed on both oblique axial plane images parallel to the long axis of the femoral neck and radial images obtained using the center of the femoral neck as the axis of rotation. The mean oblique axial plane and mean maximal radial alpha angle values were 53.4° and 70.5°, respectively. In 54% of subjects, the alpha angle was less than 55° on the conventional oblique axial plane image but 55° or greater on the radial plane images. Radial images yielded higher alpha angle values than oblique axial images. Patients with clinically suspected FAI may have a substantial contour abnormality that can be underestimated or missed if only oblique axial plane images are reviewed. Radial plane imaging should be considered in the MRI investigation of FAI.,[object Object]

Radiographic Evaluation of the Hip has Limited Reliability

John C. Clohisy MD, John C. Carlisle MD, Robert Trousdale MD, Young-Jo Kim MD, PhD, Paul E. Beaule MD, FRCSC, Patrick Morgan MD, Karen Steger-May MA, Perry L. Schoenecker MD, Michael Millis MD Radiographic evaluation provides essential information regarding the diagnosis and treatment of musculoskeletal disorders. We evaluated the ability of hip specialists to reliably identify important radiographic features and to make a diagnosis based on plain radiographs alone. Five hip specialists and one fellow performed a blinded radiographic review of 25 control hips, 25 hips with developmental dysplasia (DDH), and 27 with femoroacetabular impingement (FAI). On two separate occasions, readers assessed acetabular version, inclination and depth, position of the femoral head center, head sphericity, head-neck offset, Tönnis grade, and joint congruency. Observers made a diagnosis categorizing each hip as normal, dysplastic, FAI, or combined DDH and FAI (features of both). Reliability was determined using Cohen’s kappa coefficient. Intraobserver values were highest for acetabular inclination (κ = 0.72) and determination of femoral head center position (κ = 0.77). Interobserver reliability values were highest for acetabular inclination (κ = 0.61) and Tönnis osteoarthritis grade (κ = 0.59). All other measurements, including diagnosis, had kappa values less than 0.55. We concluded many of the standard radiographic parameters used to diagnose DDH and/or FAI are not reproducible. Accordingly, a more clear set of definitions and measurements must be developed to allow for more reliable diagnosis of early hip disease.,[object Object]

Systematic Review of the Prevalence of Radiographic Primary Hip Osteoarthritis

Simon Dagenais DC, PhD, Shawn Garbedian MD, Eugene K. Wai MD, MSc Hip osteoarthritis is a common cause of musculoskeletal pain in older adults and may result in decreased mobility and quality of life. Although the presentation of hip osteoarthritis varies, surgical management is required when the disease is severe, longstanding, and unresponsive to nonoperative treatments. For stakeholders to plan for the expected increased demand for surgical procedures related to hip osteoarthritis, including arthroplasty, it is important to first understand its prevalence. We conducted a systematic review by searching MEDLINE® and EMBASE to identify recent English language articles reporting on the prevalence of radiographic primary hip osteoarthritis in the general adult population; references including studies and primary studies from previous systematic reviews were also searched. This strategy yielded 23 studies reporting 39 estimates of overall prevalence ranging from 0.9% to 27% with a mean of 8.0% and a standard deviation of 7.0%. Heterogeneity was noted in study populations, eligibility criteria, age and gender distribution, type of radiographs, and method of diagnosis. Although the association between radiographic hip osteoarthritis and the need for eventual surgical management is still unclear, this study supports assertions that hip osteoarthritis is a prevalent condition whose treatment will continue to place important demands on health services.

The Effect of Cam FAI on Hip and Pelvic Motion during Maximum Squat

Mario Lamontagne PhD, Matthew J. Kennedy BSc, Paul E. Beaulé MD, FRCSC Femoroacetabular impingement (FAI) causes abnormal contact at the anterosuperior aspect of the acetabulum in activities requiring a large hip range of motion (ROM). We addressed the following questions in this study: (1) Does FAI affect the motions of the hip and pelvis during a maximal depth squat? (2) Does FAI decrease maximal normalized squat depth? We measured the effect of cam FAI on the 3-D motion of the hip and pelvis during a maximal depth squat as compared with a healthy control group. Fifteen participants diagnosed with cam FAI and 11 matched control participants performed unloaded squats while 3-D motion analysis was collected. Patients with FAI had no differences in hip motion during squatting but had decreased sagittal pelvic range of motion compared to the control group (14.7 ± 8.4° versus 24.2 ± 6.8°, respectively). The FAI group also could not squat as low as the control group (41.5 ± 12.5% versus 32.3 ± 6.8% of leg length, respectively), indicating the maximal depth squat may be useful as a diagnostic exercise. Limited sagittal pelvic ROM in FAI patients may contribute to their decreased squatting depth, and could represent a factor amongst others in the pathomechanics of FAI.,[object Object]

Complications of Arthroscopic Femoroacetabular Impingement Treatment: A Review

Victor M. Ilizaliturri MD Recent developments in hip arthroscopy techniques and technology have made it possible in many cases to avoid open surgical technique for treating pincer-type and cam-type femoroacetabular impingement and rather treating it arthroscopically. Early reports suggest favorable results using arthroscopic techniques. The frequency of complications reported for hip arthroscopy for all indications is generally less than 1.5%, suggesting the procedure is safe. Little information is available on complications directly related to the arthroscopic treatment of femoroacetabular impingement. Failure to recognize and treat or incompletely reshape impingement deformities may be the most frequent cause for a second hip arthroscopy and redébridement of the deformity. There has been no report of avascular necrosis related to the arthroscopic treatment of femoroacetabular impingement; only one femoral neck fracture after arthroscopic cam remodeling has been reported in a large series of patients. Other clinical concerns include hip dislocation secondary to extensive capsulotomies or overresection of the anterior acetabular rim in the case of pincer impingement.,[object Object]

Do Normal Radiographs Exclude Asphericity of the Femoral Head-Neck Junction?

Marcel Dudda MD, Christoph Albers MD, Tallal Charles Mamisch MD, Stefan Werlen MD, Martin Beck MD Asphericity of the femoral head-neck junction is one cause for femoroacetabular impingement of the hip. However, the asphericity often is underestimated on conventional radiographs. This study compares the presence of asphericity on conventional radiographs with its appearance on radial slices of magnetic resonance arthrography (MRA). We retrospectively reviewed 58 selected hips in 148 patients who underwent a surgical dislocation of the hip. To assess the circumference of the proximal femur, alpha angle and height of asphericity were measured in 14 positions using radial slices of MRA. The hips were assigned to one of four groups depending on the appearance of the head-neck junction on anteroposterior pelvic and lateral crosstable radiographs. Group I (n = 19) was circular on both planes, Group II (n = 19) was aspheric on the crosstable view, Group III (n = 4) was aspheric on the anteroposterior view, and Group IV (n = 13) was aspheric on both views. In all four groups, the highest alpha angle was found in the anterosuperior area of the head-neck junction. Even when conventional radiographs appeared normal, an increased alpha angle was present anterosuperiorly. Without the use of radial slices in MRA, the asphericity would be underestimated in these patients.,[object Object]

Impingement-free Hip Motion: The ‘Normal’ Angle Alpha after Osteochondroplasty

Mirjam Neumann MD, Quanjun Cui MD, Klaus A. Siebenrock MD, Martin Beck MD Femoroacetabular impingement is considered a cause of hip osteoarthrosis. In cam impingement, an aspherical head-neck junction is squeezed into the joint and causes acetabular cartilage damage. The anterior offset angle α, observed on a lateral crosstable radiograph, reflects the location where the femoral head becomes aspheric. Previous studies reported a mean angle α of 42° in asymptomatic patients. Currently, it is believed an angle α of 50° to 55° is normal. The aim of this study was to identify that angle α which allows impingement-free motion. In 45 patients who underwent surgical treatment for femoroacetabular impingement, we measured the angle α preoperatively, immediately postoperatively, and 1 year postoperatively. All hips underwent femoral correction and, if necessary, acetabular correction. The correction was considered sufficient when, in 90° hip flexion, an internal rotation of 20° to 25° was possible. The angle α was corrected from a preoperative mean of 66° (range, 45°–79°) to 43° (range, 34°–60°) postoperatively. Because the acetabulum is corrected to normal first, the femoral correction is tested against a normal acetabulum. We therefore concluded an angle α of 43° achieved surgically and with impingement-free motion, represents the normal angle α, an angle lower than that currently considered sufficient.

Femoral Morphology Due to Impingement Influences the Range of Motion in Slipped Capital Femoral Epiphysis

Tallal C. Mamisch MD, Young-Jo Kim MD, PhD, Jens A. Richolt MD, Michael B. Millis MD, Jens Kordelle MD Femoroacetabular impingement due to metaphyseal prominence is associated with the slippage in patients with slipped capital femoral epiphysis (SCFE), but it is unclear whether the changes in femoral metaphysis morphology are associated with range of motion (ROM) changes or type of impingement. We asked whether the femoral head-neck junction morphology influences ROM analysis and type of impingement in addition to the slip angle and the acetabular version. We analyzed in 31 patients with SCFE the relationship between the proximal femoral morphology and limitation in ROM due to impingement based on simulated ROM of preoperative CT data. The ROM was analyzed in relation to degree of slippage, femoral metaphysis morphology, acetabular version, and pathomechanical terms of “impaction” and “inclusion.” The ROM in the affected hips was comparable to that in the unaffected hips for mild slippage and decreased for slippage of more than 30°. The limitation correlated with changes in the metaphysic morphology and changed acetabular version. Decreased head-neck offset in hips with slip angles between 30° and 50° had restricted ROM to nearly the same degree as in severe SCFE. Therefore, in addition to the slip angle, the femoral metaphysis morphology should be used as criteria for reconstructive surgery.