Remodelling of femoral head-neck junction in slipped capital femoral epiphysis: a multicentre study

Good Long-Term Clinical Outcome in 50% of Hips With Mild and Moderate Chronic Slipped Capital Femoral Epiphysis Treated With in Situ Fixation: 93 Hips With a Follow-up of 50 Years

Background

There is no consensus regarding the initial treatment of slipped capital femoral epiphysis (SCFE). The aim of this study was to analyze the long-term outcome of in situ fixation (ISF) in chronic SCFE.

Methods

The study consisted of 79 patients (93 hips), treated with ISF from 1955 to 1993. There were 47 male patients (59%) and 32 female patients with a mean age of 12.8 years (range, 8-16 years) at the time of diagnosis. The mean slip angle was 33.4° (range, 12°-80°). The slip was mild (<30°) in 46 hips (49%), moderate (30°-49°) in 33 (36%), and severe (≥50°) in 14 hips. Long-term clinical outcome was based on the rate of total hip arthroplasty (THA) and the modified Harris Hip Score (mHHS) analyzed by telephone (maximum score 91 points).

Results

The mean follow-up time was 51.6 years (range, 30-68 years). Thirty-two hips (34%) had undergone THA at a mean patient age of 55.9 years (range, 21-75 years). The survival rate (percentage of hips that had not undergone THA) was 99% at 20 years of follow-up and fell to 69% (95% confidence interval, 58%-80%) at 50 years. The mean mHHS in 57 of the 61 hips that had not undergone THA was 80.7 points (range, 22-91 points). Good long-term outcome, defined as no THA and mHHS ≥76 points, occurred in 40 of 89 hips (45%). The outcome was worse in hips with severe slips compared with moderate and mild slips (p = 0.020), whereas there was no significant differences between moderate and mild slips (p = 0.817). The only independent risk factor of outcome was high alpha angle.

Conclusions

At a mean follow-up of 50 years, the clinical outcome in hips with mild or moderate slipping was good in 50% of the hips, and 27% had been converted to THA. These results are well suited for comparison with future studies of more modern treatment concepts.

Level of Evidence

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

Temporal trends in surgical implants for in situ fixation of stable slipped capital femoral epiphysis

Stable slipped capital femoral epiphysis (SCFE) is a pediatric hip disorder managed with in situ fixation of the proximal femoral epiphysis, otherwise known as 'pinning the hip'. The objective of this study was to characterize how the choice of implant for in situ fixation of stable SCFE has changed over time. A systematic review of publications concerning in situ fixation of stable SCFE from January 1993 to November 2021 was conducted. The change in the type, diameter, and number of implants used in publications over time and the age of their respective patient cohorts was evaluated. A total of 207 articles met inclusion criteria. There was an increase in publications using cannulated screws over time ( P  = 0.0113). As the yearly percentage of publications using threadless non-cannulated implants decreased ( P  = 0.0309), the percentage using cannulated screws increased ( P  = 0.0047). Single-implant fixation also increased ( P  = 0.0409). While there was no difference in the rate of increase of implants < 7 mm or ≥ 7 mm in diameter ( P  = 0.299), patients with larger-diameter implants were, on average, older than patients with smaller-diameter implants ( P  = 0.0462). In general, the age of patients undergoing in situ fixation of stable SCFE has not changed ( P  = 0.595). Irrespective of patient-specific considerations, single cannulated screws have become the implant of choice for in situ fixation of stable SCFE. There has not been a consensus on the optimal implant diameter; instead, patient-specific considerations are of paramount importance in this decision.

Radiological and clinical femoroacetabular impingement after slipped capital femoral epiphysis treated by in situ fixation

Background

The treatment of slipped capital femoral epiphysis (SCFE) is always surgical. In situ fixation (ISF) is widely accepted to stop the epiphysis slipping. Femoroacetabular impingement (FAI) is recognized as a complication after ISF and is one of the major causes of early hip osteoarthritis.

Study aim

The aim of this study was to characterize the relation between clinical and radiological signs of FAI.

Methods

A monocentric study that included all consecutive children treated for SCFE by ISF between 2006 and 2017 was performed. Clinical examination consisted in range of motion (ROM) measurement for both hips, impingements tests and functional scores (Harris Hip Score (HHS) and Womac score). Radiological analysis was based on signs of impingement (alpha angle, anterior head neck offset (OS), anterior head neck offset ratio (HNOR).

Results

36 hips were included. At follow-up, the difference between the mean hip ROM on the SCFE side and the healthy side were statistically significant in abduction and in internal rotation. Ten (28%) hips presented at least one clinical test positive for FAI (FADDIR and/or FABER). All the patients presented a good or excellent functional score. Eight patients (22%) presented all radiological signs of impingement; among these, 3 had a clinical sign of FAI. Twenty-eight hips (78%) presented at least one radiological sign of FAI; among these, 10 had clinical signs of FAI.

Conclusion

Despite a high rate of radiological FAI, less than one-third of patients have clinical signs of FAI after ISF for SCEFE.

Level of evidence

III: retrospective study.

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

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

Effect of hip dysplasia on the development of the femoral head growth plate

Purpose

The purpose of this study was to observe whether developmental dysplasia of the hip (DDH) affects the development of the femoral head growth plate and to analyze the risk factors.

Methods

We selected female patients aged between 11 and 20 years with unilateral DDH and unclosed femoral head growth plate (s). The selected patients underwent anteroposterior radiography of the hip joint to compare the degree of development of the femoral head growth plate on both sides and to identify risk factors that affect the development of the growth plate in the femoral head.

Results

We included 48 female patients with unilateral DDH, with an average age of 14 years (range: 11.1-18.5 years) and an average BMI of 20.4 kg/m² (range: 15.5 kg/m²-27.9 kg/m²). Among them, 23 patients had earlier development of the femoral head growth plate on the affected side than on the healthy side, while the degree of development of the femoral head growth plate in 25 patients was the same as that on the contralateral side. When the Tönnis angle was greater than 29.5°C and/or the Reimers migration index was greater than 48.5%, there was a statistically significant difference in the acceleration of femoral head growth plate development.

Conclusion

An abnormal relative position of the acetabulum-femoral head caused by DDH can accelerate closure of the femoral head growth plate in immature female patients. The risk factors are a Tönnis angle greater than 29.5°C and/or Reimers migration index greater than 48.5%.

Femoroacetabular impingement in the unpinned contralateral hip in patients with primary unilateral slipped capital femoral epiphysis: preliminary radiographic outcomes

The study evaluated femoroacetabular impingement (FAI) in the unpinned contralateral hip in patients with unilateral slipped capital femoral epiphysis (SCFE) and verified initial age, posterior sloping angle (PSA) and center-edge angle (CEA) as predictors of FAI in the contralateral hip. 152 patients with unilateral SCFE with a mean index age of 13.2 years (8.2-17.2 years) were enrolled retrospectively into the study. Mean follow-up was 8 years (3-14 years). PSA and CEA were measured on initial radiographs of the unaffected hip. Alpha-angle and CEA were measured on radiographs taken at the last follow-up to identify FAI. Four groups of patients were distinguished: (1) no FAI (10 patients, 17.54%); (2) CAM-type FAI (41 patients, 71.9%); (3) pincer-type FAI (3 patients, 5.26%) and (4) mixed-type FAI (13 patients, 22.8%). The mean PSA was 12.1°, 12°, 16.8°, 11.9° for groups 1, 2, 3 and 4, respectively, with no significant difference ( P  = 0.65). The mean initial CEA for groups 1, 2, 3 and 4 was 34.4°, 35.5°, 42° and 42° respectively, with significant differences between groups 1 versus 4 ( P  = 0.034) and 2 versus 4 ( P  = 0.009). Conclusions are as follows: 1. Radiographic features of FAI were present in 85.1% of unpinned contralateral hips in patients with unilateral SCFE. 2. 71.9% of unpinned contralateral hips developed CAM deformity. 3. CEA can be used in predicting pincer-type FAI in the contralateral hip in unilateral SCFE. 4. PSA and age revealed negligible value in predicting FAI.

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.

Characterizing the Residual SCFE Deformity: Utility of the 45-degree Dunn View

BACKGROUND

After treatment with in situ stabilization, slipped capital femoral epiphysis (SCFE) patients have variable degrees of deformity that can contribute to femoroacetabular impingement (FAI). To evaluate the severity of residual deformity most physicians currently use biplanar radiographs of an anteroposterior pelvis which profiles the lateral head-neck deformity and a frog lateral view which profiles the anterior head-neck deformity. However, the assessment of FAI morphology commonly relies on the 45-degree Dunn view to profile the anterolateral head-neck junction where FAI deformity is maximal. Therefore, the purpose of this study was to compare the magnitude of residual SCFE deformity detected on the frog lateral radiograph to the 45-degree Dunn radiograph.

METHODS

A retrospective review of radiographic images of 50 hips (47 patients) diagnosed with SCFE at a single academic institution from 2014 to 2018 was performed. The group included 25 hips evaluated postoperatively after fixation (Group 1) and 25 hips presenting with residual symptomatic SCFE deformity after previous pinning (Group 2). The alpha angle was assessed on both the 45-degree Dunn and frog lateral views for comparison. The modified Southwick slip angle was assessed on the frog lateral view only as a measure of SCFE severity.

RESULTS

The Dunn view showed the maximal residual SCFE deformity as measured by the alpha angle in 88% (44/50) of cases. Overall, the mean alpha angle (70.7 degree vs. 60.1 degree, P <0.001) was significantly larger on the Dunn view as compared with frog lateral. Subgroup analysis showed a larger alpha angle on Dunn view compared with frog lateral in both immediate postoperative and residual SCFE deformities as well: Group 1 (69.5 degree vs. 60.9 degree, P <0.001) and Group 2 (71.9 degree vs. 59.3 degree, P <0.001).

CONCLUSION

In patients with SCFE, the maximal residual deformity of the proximal femur can typically be seen on the 45-degree Dunn view, rather than on the frog lateral view. Our findings suggest the 45-degree Dunn view may be beneficial part of the postoperative assessment of SCFEs to quantify the true maximal deformity present.

LEVEL OF EVIDENCE

Level IV.

Advantages of Telescopic Screw in Slipped Capital Femoral Epiphysis Treatment: A Retrospective Study and Review of the Literature

Background: Slipped capital femoral epiphysis is due to proximal femur physis failure in adolescent patients. Early iatrogenic closure of proximal growth cartilage in children with significant residual growth potential causes complications such as coxa breva, coxa vara, and lower limb length inequalities. The Free-Gliding SCFE Screw System is a self-extending cannulated screw used in Slipped Capital Femoral Epiphysis (SCFE) fixation and femoral neck fractures. Materials and Method: We conducted a retrospective study on 16 patients. All patients under 11 years old were treated by telescopic cannulated screws fixation. The youngest patient was 7 years old. Results: Out of the 22 operated hips, 2 screws have failed, thus resulting in a lack of telescoping of the screw. We discovered an average lengthening of approximately 10 mm at 24 months postoperative check-up in 20 hips in which lengthening took place. According to the Notzli method, none of the patients had an alpha angle value greater than 48 degrees. Conclusion: Fixation with telescopic screw for SCFE in patients less than 11 years old, with mild to moderate slippage, allows the continuous growth and remodeling of the proximal femur, thus avoiding deformities such as coxa breva, coxa vara, FAI, AVN, limb length discrepancies and also allows good range of motion.

Leg length discrepancy after in situ fixation with screw for slipped capital femoral epiphysis

Although leg length discrepancy (LLD) commonly occurs following in situ fixation with screws for slipped capital femoral epiphysis (SCFE), the literature regarding this issue is scarce. The purpose of this study was to evaluate the degree of LLD in patients who had been treated with in situ fixation with screws and to identify the risk factors for the development of LLD. We retrospectively reviewed 44 patients (mild slip 24, moderate slip, 20) who were treated with in situ fixation with screws for SCFE. The mean age at surgery was 12.2 years and the mean follow-up period was 6.9 years. We investigated the relationship between the final LLD, articulotrochanteric distance difference (ATDD) at skeletal maturity, and various clinical and radiographic parameters using linear regression analysis. The mean values of LLD and ATDD were 13.1 and 11.1 mm, respectively. The LLD and ATDD was significantly higher in patients with moderate slips than in those with mild slips. The degree of slip angle was associated with the degree of LLD only. While there was no significant factor affecting the LLD in moderate slips, younger age and a larger degree of slip angle were associated with the degree of LLD. The degree of slip was the only factor that affected LLD in patients with mild or moderate SCFE who underwent threaded screw fixation. Age at surgery was not associated with LLD, and there were no factors related to the degree of LLD in mild slip. Monitoring for LLD may only be necessary for patients with moderate slip who are treated with in situ screw fixation.

Is the modified Dunn's procedure superior to in situ fixation? A systematic review and meta-analysis of comparative studies for management of moderate and severe slipped capital femoral epiphysis

PURPOSE

The management of moderate and severe slipped capital femoral epiphysis is controversial. While in situ fixation is commonly used, the modified Dunn's procedure is increasingly popular within high-volume centers. We compared the clinical and radiological outcomes, as well as the rates of femoral head avascular necrosis or chondrolysis in patients managed with either modified Dunn's procedure or in situ fixation.

METHODS

A systematic search of the PubMed, Embase, The Cochrane Library, Science Direct, and Web of Science was performed in August 2021. Studies comparing outcomes and complications of modified Dunn's procedure versus in situ fixation in patients with moderate or severe slipped capital femoral epiphysis were included.

RESULTS

A total of four studies were included in the final analysis. Modified Dunn's procedure did not result in improved clinical outcomes. However, radiological outcomes as measured using Southwick angles and Alpha angles were significantly improved in the modified Dunn's procedure group, with a mean difference of -14.68 (p < 0.00001) and -34.26 degrees (p < 0.00001), respectively, compared to in situ fixation. There was no difference in the odds of femoral head avascular necrosis or chondrolysis, with odds ratio of 0.99 (p = 0.97).

CONCLUSION

Within the limits of our study, modified Dunn's procedure did not improve clinical outcomes. There were significantly improved radiological outcomes without higher odds of femoral head avascular necrosis or chondrolysis. Further long-term studies are required to better guide management of moderate and severe slipped capital femoral epiphysis, especially in unstable slips. In the meantime, we recommend that the modified Dunn's procedure, if done, be restricted to high-volume centers with low complication rates.

LEVEL OF EVIDENCE

Level III-Systematic review of Level III studies.

PROSPERO REGISTRATION NO

CRD42021279503.

Is a Femoro-Acetabular Impingement Type Cam Predictable after Slipped Capital Femoral Epiphysis?

(1) Background: Previous studies have proven a high incidence of a femoro-acetabular impingement (FAI) type cam in patients sustaining a slipped capital femoral epiphysis (SCFE). Thus, the current study analyzed, if a cam deformity is predictable after SCFE treatment; (2) Methods: 113 cases of SCFE were treated between 1 January 2005 and 31 December 2017. The radiological assessment included the slip angle after surgery (referenced to the femoral neck (epiphyseal tilt) and shaft axis as Southwick angle) and the last available lateral center edge angle (LCEA), the acetabular- and alpha angle. A correlation was performed between these parameters and the last alpha angle to predict a FAI type cam; (3) Results: After a mean follow-up of 4.3 years (±1.9; 2.0-11.2), 48.5% of the patients showed a FAI type cam and 43.2% a dysplasia on the affected side. The correlation between the epiphyseal tilt and alpha angle was statically significant (p = 0.017) with a medium effect size of 0.28; (4) Conclusions: The postoperative posterior epiphyseal tilt was predictive factor to determine the alpha angle. However, the cut-off value of the slip angle was 16.8° for a later occurrence of a FAI type cam indicating a small range of acceptable deviations from the anatomical position for SCFE reconstruction.

Outcomes of distally un-threaded screw fixation of slipped capital femoral epiphysis at skeletal maturity: a matched cohort study

The most common treatment for slipped capital femoral epiphysis worldwide is in situ fixation with a threaded screw. Un-threaded screws are designed to prevent slip progression without hindering residual growth of the proximal femur. This study aimed to compare growth, remodelling and long-term outcomes after fixation with un-threaded screws and a matched cohort of patients treated with a standard screw. Six patients (nine hips) treated with un-threaded screws and 16 patients (21 hips) treated with standard screws matched for age, skeletal maturity, sex and Southwick angle were recruited. Clinical records were reviewed for patient demographics, medical history and complications. Radiographs were reviewed for residual growth and time to physeal closure. Growth velocity was calculated. Absence of cam deformity signified complete remodelling. Clinical assessment was graded from excellent to poor and patient-reported outcomes were recorded. There was significantly more growth recorded in the un-threaded screw group in femoral neck length (7.6 mm, P = 0.003), articulo-lesser trochanter distance (5.3 mm, P = 0.028), pin-joint ratio (7.439%, P = 0.006) and pin-physis ratio (8.244%, P = 0.001). The probability of revision operations due to ongoing growth was higher in this group (risk ratio: 6.57, P = 0.0008). Time to physeal closure was not significantly different, but growth velocity was significantly higher in the un-threaded group. The lower probability of cam deformity was not significant. Functional and clinical results were not significantly different at average 11.2 years' follow-up. Un-threaded screws allow for significantly more growth than standard threaded screws. The un-threaded screw could not be recommended due to the higher re-operation rates, without any proven benefit.

Proximal femoral epiphyseal spurs and their association with acetabular labral tears on MRI in symptomatic patients

OBJECTIVE

Femoral epiphyseal spurs are developmental projections that form at the edge of the physis. Although considered incidental, their association with acetabular labral tears has never been examined. Our aim was to assess the prevalence of femoral epiphyseal spurs in symptomatic patients with mechanical hip pain and explore if they are associated with labral tears on MRI.

MATERIALS AND METHODS

Hip MRI scans performed on a Siemens 3 T MRI using femoroacetabular impingement protocol were retrospectively reviewed. All patients were referred by orthopaedic surgeons for mechanical hip pain. Two musculoskeletal radiologists blinded to initial reports evaluated MRI images for the presence of an epiphyseal spur and acetabular labral changes. A consensus was achieved on all cases by the two readers. The association between epiphyseal spurs and labral changes was assessed using Fisher's exact test.

RESULTS

A total of 115 patients (178 hip MRI scans) were reviewed; the mean age was 28.8 years (SD 7.1). There were 52 females (45.2%) and 63 males (54.8%). There were 115 hips with labral tears (64.6%). Fourteen hips (7.8%) in ten patients (8.7%) demonstrated epiphyseal spurs and all of them showed labral tears (100%). There was statistically significant association between epiphyseal spurs and labral tears on MRI (p value = 0.0024).

CONCLUSION

Femoral epiphyseal spurs were observed in 8.7% of our defined patient population, and all patients with epiphyseal spurs demonstrated labral tears. Epiphyseal spurs should be documented on imaging reports due to their potential association with labral tears. Future research is needed to further delineate and guide management of these entities.

Quantitative Evaluation of Hip Muscle Atrophy in Patients with Unilateral Slipped Capital Femoral Epiphysis Based on Magnetic Resonance Imaging

RATIONALE AND OBJECTIVES

Hip muscle atrophy commonly occurs in patients with unilateral slipped capital femoral epiphysis (SCFE), its effect in patients with unilateral SCFE is worthy of further investigation. This study aimed to investigate the relationship between hip muscle cross-sectional area (M-CSA) and unilateral SCFE using magnetic resonance imaging.

MATERIALS AND METHODS

Overall, 32 unilateral SCFE patients (SCFE group) and 15 asymptomatic subjects (control group) were evaluated. All patients underwent magnetic resonance imaging and frog-leg lateral radiograph examinations. M-CSA and Southwick angle were evaluated to calculate the M-CSA ratio of the affected side over the healthy side (A/H) ratio in the SCFE group and the control group. Associations between the A/H ratio, Southwick angle, and the disease time course were investigated with Spearman correlation test. An independent sample t-test, one-way analysis of variance tests, and intraclass correlation coefficients were also applied.

RESULTS

A/H ratios of the control group were significantly higher than those of the SCFE group (anterior muscles group: 1.09 ± 0.14 vs 0.86 ± 0.12, medial muscles group: 1.02 ± 0.15 vs 0.82 ± 0.18, posterior muscles group: 1.03 ± 0.07 vs 0.84 ± 0.11, all p < 0.01). A/H ratios of the medial and posterior muscle groups were significantly correlated with severity of SCFE (r = -0.504, p = 0.003, and r = -0.438, p = 0.012, respectively).

CONCLUSION

Hip muscle atrophy is associated with SCFE severity in patients with unilateral SCFE. The A/H ratio can reflect the patients' prognosis and rehabilitation status. Maintenance of hip muscle morphology and function may be beneficial to clinical performance and prognosis of patients with unilateral SCFE.

How Common Is Femoral Retroversion and How Is it Affected by Different Measurement Methods in Unilateral Slipped Capital Femoral Epiphysis?

BACKGROUND

Although femoral retroversion has been linked to the onset of slipped capital femoral epiphysis (SCFE), and may result from a rotation of the femoral epiphysis around the epiphyseal tubercle leading to femoral retroversion, femoral version has rarely been described in patients with SCFE. Furthermore, the prevalence of actual femoral retroversion and the effect of different measurement methods on femoral version angles has yet to be studied in SCFE.

QUESTIONS/PURPOSES

(1) Do femoral version and the prevalence of femoral retroversion differ between hips with SCFE and the asymptomatic contralateral side? (2) How do the mean femoral version angles and the prevalence of femoral retroversion change depending on the measurement method used? (3) What is the interobserver reliability and intraobserver reproducibility of these measurement methods?

METHODS

For this retrospective, controlled, single-center study, we reviewed our institutional database for patients who were treated for unilateral SCFE and who had undergone a pelvic CT scan. During the period in question, the general indication for obtaining a CT scan was to define the surgical strategy based on the assessment of deformity severity in patients with newly diagnosed SCFE or with previous in situ fixation. After applying prespecified inclusion and exclusion criteria, we included 79 patients. The mean age was 15 ± 4 years, 48% (38 of 79) of the patients were male, and 56% (44 of 79) were obese (defined as a BMI > 95th percentile (mean BMI 34 ± 9 kg/m2). One radiology resident (6 years of experience) measured femoral version of the entire study group using five different methods. Femoral neck version was measured as the orientation of the femoral neck. Further measurement methods included the femoral head's center and differed regarding the level of landmarks for the proximal femoral reference axis. From proximal to distal, this included the most-proximal methods (Lee et al. and Reikerås et al.) and most-distal methods (Tomczak et al. and Murphy et al.). Most proximally (Lee et al. method), we used the most cephalic junction of the greater trochanter as the landmark and, most distally, we used the center base of the femoral neck superior to the lesser trochanter (Murphy et al.). The orientation of the distal femoral condyles served as the distal reference axis for all five measurement methods. All five methods were compared side-by-side (involved versus uninvolved hip), and comparisons among all five methods were performed using paired t-tests. The prevalence of femoral retroversion (< 0°) was compared using a chi-square test. A subset of patients was measured twice by the first observer and by a second orthopaedic resident (2 years of experience) to assess intraobserver reproducibility and interobserver reliability; for this assessment, we used intraclass correlation coefficients.

RESULTS

The mean femoral neck version was lower in hips with SCFE than in the contralateral side (-2° ± 13° versus 7° ± 11°; p < 0.001). This yielded a mean side-by side difference of -8° ± 11° (95% CI -11° to -6°; p < 0.001) and a higher prevalence of femoral retroversion in hips with SCFE (58% [95% CI 47% to 69%]; p < 0.001) than on the contralateral side (29% [95% CI 19% to 39%]). These differences between hips with SCFE and the contralateral side were higher and ranged from -17° ± 11° (95% CI -20° to -15°; p < 0.001) based on the method of Tomczak et al. to -22° ± 13° (95% CI -25° to -19°; p < 0.001) according to the method of Murphy et al. The mean overall femoral version angles increased for hips with SCFE using more-distal landmarks compared with more-proximal landmarks. The prevalence of femoral retroversion was higher in hips with SCFE for the proximal methods of Lee et al. and Reikerås et al. (91% [95% CI 85% to 97%] and 84% [95% CI 76% to 92%], respectively) than for the distal measurement methods of Tomczak et al. and Murphy et al. (47% [95% CI 36% to 58%] and 60% [95% CI 49% to 71%], respectively [all p < 0.001]). We detected mean differences ranging from -19° to 4° (all p < 0.005) for 8 of 10 pairwise comparisons in hips with SCFE. Among these, the greatest differences were between the most-proximal methods and the more-distal methods, with a mean difference of -19° ± 7° (95% CI -21° to -18°; p < 0.001), comparing the methods of Lee et al. and Tomczak et al. In hips with SCFE, we found excellent agreement (intraclass correlation coefficient [ICC] > 0.80) for intraobserver reproducibility (reader 1, ICC 0.93 to 0.96) and interobserver reliability (ICC 0.95 to 0.98) for all five measurement methods. Analogously, we found excellent agreement (ICC > 0.80) for intraobserver reproducibility (reader 1, range 0.91 to 0.96) and interobserver reliability (range 0.89 to 0.98) for all five measurement methods in healthy contralateral hips.

CONCLUSION

We showed that femoral neck version is asymmetrically decreased in unilateral SCFE, and that differences increase when including the femoral head's center. Thus, to assess the full extent of an SCFE deformity, femoral version measurements should consider the position of the displaced epiphysis. The prevalence of femoral retroversion was high in patients with SCFE and increased when using proximal anatomic landmarks. Since the range of femoral version angles was wide, femoral version cannot be predicted in a given hip and must be assessed individually. Based on these findings, we believe it is worthwhile to add evaluation of femoral version to the diagnostic workup of children with SCFE. Doing so may better inform surgeons as they contemplate when to use isolated offset correction or to perform an additional femoral osteotomy for SCFE correction based on the severity of the slip and the rotational deformity. To facilitate communication among physicians and for the design of future studies, we recommend consistently reporting the applied measurement technique.

LEVEL OF EVIDENCE

Level III, prognostic study.

Subtle Slipped Capital Femoral Epiphysis Is not Associated With Idiopathic Cam Morphology

BACKGROUND

The etiology of idiopathic cam morphology remains unclear. One theory suggests that subtle slipped capital femoral epiphysis (SCFE) leads to proximal femoral changes resulting in cam morphology. The purpose of this study was to evaluate the association between subtle SCFE and cam morphology in a large osteological collection.

METHODS

We examined 962 cadaveric hips to measure 2 markers of cam morphology, alpha angle and anterior femoral head-neck offset (AHNO), and a validated, objective marker of subtle SCFE deformity (calcar ridge line offset). When the femur is viewed medially, the calcar ridge line extends from the lesser trochanter proximally along the postero-inferior femoral neck and points toward the fovea. In SCFE-like deformity, the fovea deviates posteriorly from this projected line. Pearson correlations were performed to evaluate for possible association of calcar ridge line offset with alpha angle and AHNO. In addition, a multiple regression analysis was performed to determine the influence of age, alpha angle, and AHNO on calcar ridge line offset.

RESULTS

There was no clinically relevant association between the calcar ridge line offset and alpha angle (r=-0.02, P=0.58) or AHNO (r=0.08, P=0.012). Furthermore, specimens whose calcar ridge line deviated 1 SD above the mean (more SCFE-like deformity) had a smaller alpha angle (46.6±9.1 vs. 48.3±10.6, P=0.046) and greater AHNO (0.83±0.19 vs. 0.77±0.16, P<0.001), both reflecting less cam-like morphology. On regression analysis, increasing age and increasing AHNO (decreased cam morphology) predicted increased calcar ridge line offset, though the model accounted for only 1.2% of the variance.

CONCLUSIONS

Subtle SCFE-like deformity, as objectively measured from the calcar ridge line, was not predictive of more cam-like morphology, and in fact mild opposite associations were found. Further study is needed to identify other potential etiologies of idiopathic cam morphology.

CLINICAL RELEVANCE

We present evidence from a large, well-documented osteological collection indicating that subtle SCFE is not associated with idiopathic cam morphology.

Femoral Neck Growth and Remodeling With Free-Gliding Screw Fixation of Slipped Capital Femoral Epiphysis

BACKGROUND

Treatment of stable slipped capital femoral epiphysis (SCFE) most commonly involves in situ fixation with a standard cannulated screw, leading to physeal arrest. Recently, Pega Medical (Laval, Canada) introduced the free-gliding (FG) SCFE screw, which employs a growth-friendly, telescopic design. This study examines femoral neck growth and remodeling over the first 2 postoperative years in stable SCFE treated with FG versus standard screws.

METHODS

We retrospectively reviewed 32 hips (19 SCFE, 13 prophylactic) in 16 patients treated with FG screws for stable SCFE. We also reviewed 102 hips (63 SCFE, 19 prophylactic, 20 controls) in 55 patients treated with standard screws. Immediate postoperative radiographs were compared with 1- and 2-year follow-up images.

RESULTS

For the overall study cohort, mean age at surgery was 12.2±1.9 years, with a mean slip angle of 26.9±18.0 degrees. In FG SCFE hips, the alpha angle remodeled 12.9±19.2 degrees in the first postoperative year (P=0.018) and articulotrochanteric distance decreased by 4.2±4.6 mm at 2 years (P=0.018). In standard SCFE hips, the alpha angle remodeled 4.3±11.3 degrees at 1 year (P=0.014), while articulotrochanteric distance decreased by 4.5±3.2 mm at 2 years (P<0.001). By 2 years, FG screws lengthened more in prophylactic (4.8±3.4 mm) than SCFE hips (1.7±1.8 mm, P=0.027).

CONCLUSIONS

Greater remodeling of femoral neck cam deformity occurs when treating SCFE using an FG screw. Further research is required to measure the impact of this finding on femoroacetabular impingement and degenerative arthritis. In addition, FG screws allow ongoing growth of prophylactically treated hips, while standard screws promote coxa breva.

LEVEL OF EVIDENCE

Level III-retrospective comparative, therapeutic study.

Mid-term results after in situ pinning and hip arthroscopy for mild slipped capital femoral epiphysis: a minimum five-year follow-up

PURPOSE

In situ pinning of mild slipped capital femoral epiphysis (SCFE) results in an aspherical head-neck junction and arthroscopic osteochondroplasty can successfully correct the head-neck junction. However, whether the correction stays stable over at least five years remains unknown.

METHODS

In a retrospective and consecutive series, 11 patients with a mean age of 12 years (range, 10 years to 15 years) were included. All patients were treated for mild SCFE with in situ pinning and staged hip arthroscopy correcting the head-neck junction. All patients were assessed clinically and radiographically (radiograph and magnetic resonance imaging (MRI)) pre-operatively, 12 weeks and at least five years' post-operatively.

RESULTS

The mean range of motion (ROM) for flexion and internal rotation was stable over time with 100° (sd 4) and 21° (sd 6), respectively at the last follow-up. The mean alpha angle decreased from pre-operative 64° (range 61° to 68°) to 12 weeks post-operative 49° (range 46° to 52°; p = 0.001) and stayed stable over time. New superficial cartilage damage on either the acetabular or femoral side was seen in each three patients. Progressive labral degeneration was present in two patients.

CONCLUSION

In situ pinning and staged hip arthroscopy for the correction of mild SCFE is safe, restores normal alpha angles and reveals stable morphological correction at mid-term follow-up. Furthermore, the clinical results were excellent with almost normalized internal hip rotation at mid-term follow-up in patients who had reached adulthood. However, there was some joint deterioration, but without negative impact on subjective and clinical outcome after at least five years.

LEVEL OF EVIDENCE

IV.

[Slipped Capital Femoral Epiphysis]

Slipped capital femoral epiphysis is the most common hip disease during infancy and adolescence. The incidence of this disease increases continuously. The reason is the likewise increasing body mass index of these age groups. Early diagnostic and treatment are necessary to avoid complications and consequential damages. Primary aims of the treatment are to avoid a further slip of the epiphysis and to reduce the resulting cam-deformity by reposition or osteotomy. After the end of physiological remodelling the rest of cam-deformity should be treated before an early osteoarthritis after slipped capital femoral epiphysis can be developed. There are open as well as arthroscopic surgical procedures for recontouring the femoral neck. The question at hand is to find out which surgical procedure will lead to an improvement of the long term results of slipped capital femoral epiphysis.

Factors Affecting Outcomes of Slipped Capital Femoral Epiphysis

Slipped capital femoral epiphysis (SCFE) is a frequent cause of nontraumatic painful hip of the adolescence. It is the result of the separation of the proximal femoral growth cartilage at the level of the hypertrophic cell zone. The femoral neck metaphysis rotates externally and migrates proximally relative to the femoral head epiphysis, which is stably seated in the acetabulum; early diagnosis and in situ stabilization grants the best long term results. Numerous factors affect treatment outcomes. Not all implants have the same effect on the slipped physis. Application of the traditionally used implants, such as non-threaded pins and cannulated screws, is questioned. Modern implants are available, which stabilize the slip without accelerating physis fusion. This allows femoral head and neck growth and remodeling to limit the post-slip sequellae on hip anatomy and function. Femoroacetabular impingement (FAI) complicates almost all slips. It causes progressive labral and articular cartilage damage and leads to early hip osteoarthritis and total hip replacement, approximately ten years earlier compared to the general population. Avascular necrosis of the femoral head is a dramatic complication, seen almost exclusively in unstable slips. It develops within months after the slip and leads to immediate articular joint degeneration and the need for total hip replacement. Another serious complication of SCFE is chondrolysis, which is a rapid progressive articular cartilage degeneration leading to a narrow joint space and restriction of hip motion. Implant-related complications, such as migration and loosening, may lead to the progression of the slip. Though bilateral disease is quite frequent, there is no consensus about the need for preventive surgery on the healthy contralateral hip. Diagnosis of SCFE is frequently missed or delayed, leading to slips of higher severity. Silent slippage of the capital femoral epiphysis is highly suspected as an underlying cause of cam-type FAI and early-onset hip osteoarthritis. There is controversy, whether asymptomatic implants should be removed. Novel surgical techniques, such as the modified Dunn procedure and hip arthroscopy, seem to be effective modalities for the prevention of FAI in SCFE.

Biomechanical Evaluation of the Depth of Resection During Femoral Neck Osteoplasty for Anterior Impingement Following Slipped Capital Femoral Epiphysis

BACKGROUND

Femoroacetabular impingement as a result of slipped capital femoral epiphysis (SCFE) has been treated traditionally with a proximal femoral osteotomy, but open and arthroscopic femoral osteoplasty is becoming increasingly popular. Cam lesions result from excess bone primarily at the anterolateral femoral head-neck junction. SCFEs result from posterior and inferior slippage of the femoral epiphysis, causing the metaphysis to move anteriorly. This study's purpose was to compare fourth-generation sawbones standard femurs with SCFE femurs to determine whether bone resection from the anterior metaphysis results in similar biomechanical properties.

METHODS

A custom fourth-generation composite SCFE sawbone was created with a 30-degree slip angle. Control group consisted of fourth-generation composite standard nondeformed medium femurs. The femoral neck at the head-neck junction was divided into 4 quadrants. All resections were done in the anterolateral quadrant. Twenty SCFE sawbones and 20 standard sawbones were divided into 4 subgroups based on resection depths of 0%, 10%, 30%, and 50% of the metaphysis at the head-neck junction. After resection, all proximal femurs were loaded to failure in an Instron testing machine to determine the ultimate load to failure, stiffness, and energy to failure.

RESULTS

The standard femurs were significantly stronger than the SCFE femurs (P<0.001) and the strength of the femurs decreased significantly as the resection amount increased (P<0.001). Similarly, the standard femurs withstood significantly more energy before failing than the SCFE femurs (P<0.001) and the energy to failure decreased significantly with varying resection amounts (P<0.001).

CONCLUSIONS

SCFE femurs demonstrate a significant reduction in strength and energy to failure after osteoplasty compared with nondeformed femurs in a sawbone model. Strength and energy to failure are inversely proportional to the depth of bone resection.

CLINICAL RELEVANCE

Aggressive femoral neck osteoplasty for treatment of a SCFE deformity may lead to increased risk of fracture. Further studies are necessary to determine the safe depth of resection in a clinical setting.

The effects of residual hip deformity on coronal alignment of the lower extremity in patients with unilateral slipped capital femoral epiphysis

PURPOSE

The aim of our explorative study was to compare the differences in the coronal alignments of the hip, knee and ankle on the slip side and non-slip sides in patients with slipped capital femoral epiphysis (SCFE).

METHODS

The study group consisted of 28 patients. On the full-length standing radiographs, measurements of articulo-trochanteric distance (ATD), neck-shaft angle (NSA), femoral offset, hip-knee-ankle axis, femur-tibial angle, mechanical axis deviation ratio (MAD-r), anatomical medial proximal femoral angle (aMPFA), mechanical lateral proximal femoral angle (mLPFA), anatomical lateral distal femoral angle (aLDFA), mechanical lateral distal femoral angle (mLDFA), knee joint line congruency angle, mechanical medial proximal tibial angle (mMPTA), mechanical lateral distal tibial angle (mLDTA), ankle joint line orientation angle (AJOA), and leg length discrepancy (LLD) were performed. The data from the slip side were compared with those from the non-slip side.

RESULTS

At skeletal maturity, there were significant differences between the slip side and non-slip side in ATD (p <0.001), NSA (p <0.001), MAD-r (p <0.001), aMPFA (p <0.001), aLDFA (p = 0.03), mLDFA (p = 0.04), mLDTA (p = 0.02), AJOA (p <0.001) and LLD (p<0.001).

CONCLUSION

Residual deformity in the proximal femur after epiphyseal slip and premature epiphysiodesis could cause changes in the coronal alignment of the lower extremity. We can add lower extremity alignment examination to follow-up protocol to rule out secondary problems in patients with SCFE.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Similar femoral growth and deformity with one screw versus two smooth pins for slipped capital femoral epiphysis

PURPOSE

To compare longitudinal growth and cam deformity of the proximal femur after treatment for slipped capital femoral epiphysis (SCFE) with one screw versus two smooth pins.

METHODS

We studied 43 patients (29 males, 14 females; mean age, 12.1 years; range, 9.5-14 years) with idiopathic unilateral SCFE treated with in situ fixation with one cannulated screw (group A, n = 23) or two smooth pins (group B, n = 20). Anteroposterior and frog-leg radiographs of the pelvis were evaluated for each patient at initial presentation, post-operatively and at physeal closure. Longitudinal growth was evaluated using the femoral neck length (FNL), the caput-collum-diaphyseal (CCD) angle, and the articulo-trochanteric distance (ATD). Cam deformity was assessed using the anterior offset α-angle and the head-neck offset ratio (HNOR). The mean follow-up was 5.1 years (range, 4-7 years).

RESULTS

Postoperatively, the mean CCD angle was 138.3°, the mean α-angle was 66.1° and the mean HNOR was - 0.030. At physeal closure, mean CCD angle significantly decreased to 133.6°, mean α-angle significantly reduced to 52.1°, and mean HNOR significantly improved to + 0.039. CCD, FNL, ATD, α-angle, and HNOR were not different between groups.

CONCLUSIONS

One screw or two smooth pins result in similar longitudinal growth and deformity of the proximal femur after SCFE. The femoral head-neck junction remarkably improves until physeal closure; however, residual cam deformity is not avoided after in situ pinning. The complication rate with smooth pins is higher.

Outcome of pinning in patients with slipped capital femoral epiphysis: risk factors associated with avascular necrosis, chondrolysis, and femoral impingement

Objective This study aimed to assess the principal risk factors that could lead to the most common long-term complications of slipped capital femoral epiphysis, such as avascular necrosis, chondrolysis, and hip impingement. Methods We conducted a single-centre, retrospective study and evaluated patients (70 patients, 81 hips) who were treated for slipped capital femoral epiphysis from 2010 to 2015 and who underwent pinning. We measured the severity of displacement radiologically using the Southwick angle. Postoperative radiographs were evaluated for the most frequent long-term complications of avascular necrosis (AVN), chondrolysis, and femoral acetabular impingement (FAI). Results We found seven cases of AVN, 14 cases of chondrolysis, and 31 hips had an α angle of 60°. Sex, ambulation, and symptoms did not affect development of these complications. Patients with a normal weight were almost two times more likely to develop FAI. Patients with moderate and severe slips had a similar percentage of AVN. In severe slips, 85.7% of patients had an α angle higher than 60°. Conclusions This study shows that severe slips have a higher risk of developing AVN and hip impingement. Every patient who suffers from SCFE (even the mildest forms) should be regularly checked for FAI.

Continued Growth of the Femoral Neck Leads to Improved Remodeling After In Situ Fixation of Slipped Capital Femoral Epiphysis

BACKGROUND

Globally, the most common method for in situ fixation of slipped capital femoral epiphysis (SCFE) is a threaded screw, which causes physeal arrest. The standard treatment in Sweden is unthreaded fixation using the Hansson hook-pin, which leads to continued growth of the femoral neck. Our purpose was to study remodeling during the remaining growth after fixation with the Hansson hook-pin.

METHODS

We performed a retrospective study of 54 patients with SCFE who were treated with the Hansson hook-pin between 2001 and 2009. The immediate postoperative radiograph and the radiograph taken after physeal closure (mean interval, 34 mo) were analyzed. Three radiographic assessments were used: the head-shaft angle (HSA), the alpha angle (Nötzli), and the displacement from Klein's line.

RESULTS

Significant remodeling was detected in all measured parameters. The mean postoperative HSA decreased by 9.0 degrees (P<0.001). The alpha angle improved by a mean of 14.5 degrees (P<0.001). Significant correlations were found between the reduction of the alpha angle and age (P<0.001, R=0.48) and longitudinal growth of the femoral neck (P<0.001, R=0.67). Displacement from Klein's line increased by a mean of 1.6 mm (P=0.006).

CONCLUSIONS

Unthreaded fixation of SCFE using the Hansson hook-pin leads to substantial remodeling of the femoral neck. The positive correlation observed between the improvement of the alpha angle and femoral neck growth supports the use of a method that allows continuous growth, to reduce the risk of femoroacetabular impingement.

LEVEL OF EVIDENCE

Level III-retrospective comparative study.

Origin of Cam Morphology in Femoroacetabular Impingement

Cam morphology of the proximal femur is an abnormal contour of the femoral head-neck junction present in approximately 15% to 25% of the asymptomatic population, predominantly in males. Alpha angle and femoral head-neck offset ratio are 2 objective measurement tools that define cam morphology. Both primary (idiopathic) and secondary cam deformity develops through distinct mechanisms. The cause of primary (idiopathic) cam morphology remains incompletely understood. Mounting evidence suggests that idiopathic cam morphology develops during adolescence through alterations in the capital femoral epiphysis in response to participation in vigorous sporting activity. While the exact cause of epiphyseal extension has not yet been determined, preliminary evidence suggests that epiphyseal extension may reflect a short-term adaptive response to provide stability to the physis at the long-term cost of the development of cam morphology. Commonly recognized causes of secondary cam deformity include frank slipped capital femoral epiphysis, Legg-Calve-Perthes disease, and deformity after fracture of the proximal femur. Recent studies also support subtle slipped capital femoral epiphysis as a unique and silent cause of a small percentage of subjects previously thought to have idiopathic cam deformity.

Long-term Results of Combined Epiphysiodesis and Imhauser Intertrochanteric Osteotomy in SCFE: A Retrospective Study on 53 Hips

BACKGROUND

The management of moderate and severe slipped capital femoral epiphysis is still an issue. The main concern is represented by the choice of an intra-articular or an extra-articular osteotomy to correct the deformity. Theoretically, the intra-articular osteotomy allows the best correction, but it is technically demanding and involves a higher risk of avascular necrosis (AVN); conversely, an extra-articular intertrochanteric osteotomy (ITO) is easier and involves a lower risk of early complications, but may lead to femoroacetabular impingement, resulting in early osteoarthritis and the need for total hip replacement (THR).The aim of this study was to analyze the long-term survivorship free from THR after combined epiphysiodesis and Imhauser ITO.

METHODS

From 1975 to 2000, 45 patients (53 hips) underwent a combined epiphysiodesis and Imhauser ITO. There were 27 male and 18 female patients with an average age of 12.8±1.9 years. All cases showed a posterior sloping angle >40 degrees (mean, 69±16 degrees). The cumulative survivorship was determined according to Kaplan and Meier, with the end point defined as conversion to THR.

RESULTS

A total of 6 patients (6 hips; 11%) had a follow-up <2 years. Among them, no postoperative complications occurred. For the remaining 39 patients (47 hips, 89%), the mean follow-up was 21±11 years. Four early postoperative complications were reported (2 AVN, 2 chondrolysis). The cumulative 39 years' survivorship free from THR was 68.5% (95% confidence interval, 42.4%-84.7%). The age at surgery (hazard ratio=1.849 per year older, P=0.017) and the postoperative onset of AVN or chondrolysis (hazard ratio=10.146, P=0.010) affected the long-term prognosis significantly.

CONCLUSIONS

The combined epiphysiodesis and Imhauser ITO is a valid surgical option in moderate to severe slipped capital femoral epiphysis, preserving the natural hip for at least 39 years in the majority of the patients. Care must be taken to avoid AVN or chondrolysis. The age at surgery affects the prognosis negatively.

LEVEL OF EVIDENCE

Level III-a retrospective study.

The Etiology of Cam-type Femoroacetabular Impingement: A Cadaveric Study

BACKGROUND

There is a dearth of literature examining the causes of cam-type femoroacetabular impingement (FAI) and when such morphology appears. The purpose of the current study was to analyze how the ossific portion of the proximal femur develops over time with respect to standard cam-type FAI parameters.

METHODS

A collection of 193 femurs from cadavers aged 4 to 21 years were evaluated. The age, sex, ethnicity, and status of the proximal femoral physes (open or closed) of each were recorded. Each specimen was digitally photographed in standardized anteroposterior and modified axial positions. From these photographs, the anterior offset, anterior offset ratio (AOR), and α-angle were determined. A cam lesion was defined as an α-angle >55 degrees on the lateral view.

RESULTS

The mean age of the specimens was 17.5±4.2 years. The majority were male (69%) and African American (79%) with closed physes (78%). There were significant differences among discrete age groups with respect to α-angle (P=0.01), anterior offset (P<0.01), and AOR (P<0.01). In addition, younger femurs with open physes had a significantly higher mean α-angle (P<0.01), lower mean anterior offset (P<0.01), and higher mean AOR (P<0.01) compared with older ones with closed physes. Specimens defined as having a cam deformity had a statistically higher α-angle (P<0.01) and lower anterior offset (P<0.01), but there was no difference in AOR values compared with specimens without a cam lesion (P=0.1).

CONCLUSIONS

The apparent decline in α-angles as age increases indicates that the traditional α-angle in younger patients measures a different anatomic parameter (ossified femur excluding the cartilaginous portion) than in older patients (completely ossified femur). This suggests that the bony α-angle is inappropriate in the evaluation of cam lesions in the immature physis. The AOR, rather than the anterior offset, may be more accurate in the evaluation of the growing proximal femur.

CLINICAL RELEVANCE

This study provides novel insight into, and enhances the understanding of, the development of cam-type FAI.

Anterior greater trochanteric muscle pedicle bone grafting: a viable graft option adjunct to hip osteotomy or fracture surgery

INTRODUCTION

The objectives were to evaluate a technique, outcome and complications following anterior greater trochanteric with gluteus medius muscle pedicle bone graft (AMG) procedure in the treatment of adolescent and active adult hip disorders.

METHODS

20 patients (20 hips) with a mean age of 22.7 ± 15.6 (range 10.0-63.5) years who had undergone AMG and been followed up more than 12 months postoperative were retrospectively enrolled in our study. The AMG procedure was performed in conjunction with subcapital osteotomy for slipped capital femoral epiphysis in 12 and open reduction for fracture/dislocation in 8 hips. At the most recent evaluation, patient functional status was rated by the Harris Hip Score (HHS) and radiographic changes were graded according to Tönnis criteria. Complications were defined as Tönnis grade >2 or hip requiring further surgery. Univariate analysis was used to explore factors associated with complications. Spearman's rank correlation coefficient was calculated between HHS and Tönnis grading.

RESULTS

At mean follow-up of 4.4 ± 2.6 (range 1.1-9.5) years, mean HHS was 87.4. Tönnis grading was rated as 0 in 10 hips, 1 in 5 hips, 2 in 2 hips, and 3 in 3 hips. Avascular necrosis of the femoral head as a complication developed in 3 hips (15%). Clinical parameters including age at surgery, duration of follow-up and diagnosis were not significantly associated with postoperative complications. A negative correlation between HHS and Tönnis grade was shown by Spearman's rank correlation (rs = -0.49, p = 0.03).

CONCLUSIONS

The AMG can be safely recommended as an adjunct bone graft procedure when performing anterior open reduction of adolescent and active adult hip disorders.

SCFE: clinical aspects, diagnosis, and classification

PURPOSE

This article seeks to improve treatment outcomes in slipped capital femoral epiphysis (SCFE) by outlining advances in diagnosis, understanding of pathomechanics, and mechanically-based classification.

METHODS

Review of clinical experience with SCFE at our high-volume centre, interaction with other clinical experts, and literature review has allowed a current perspective to be articulated.

RESULTS

SCFE remains an important clinical problem, with late diagnosis still frequent. Improved understanding of the ubiquity of femoroacetabular impingement has guided current classification and treatment protocols.

CONCLUSION

SCFE is an important clinical problem, with high historical rates of impaired hip function both in childhood and adulthood. Great opportunities exist for improved outcomes following earliest possible clinical diagnosis, modern imaging, and mechanically-based classification of involved hips to allow optimal treatment.

Slipped capital femoral epiphysis: long-term outcome and remodelling after in situ fixation

PURPOSE

In primary treatment of slipped capital femoral epiphysis (SCFE) in situ fixation reliably prevents slip progression. The aim of this study was to examine the long-term outcome of SCFE-patients treated by transfixation with Kirschner wires with a special focus on the remodelling process of the hips under this fixation method.

METHODS

30 patients with stable SCFE (mean initial slip angle: 29°, mean follow-up: 10 years), who were treated with bilateral transfixation by Kirschner wires, were recruited for this study. At most recent follow-up patients were clinically and radiologically (X-ray and MRI) examined. Medical records were reviewed for previous follow-up time points.

RESULTS

Range of motion: At most recent follow-up the mean range of motion was: extension/flexion: 0/0/121, abduction/adduction: 44/0/31, external rotation/internal rotation: 39/0/24. Nearly all dimensions of motion significantly improved during the postoperative course.Head-shaft angle: We saw a significant reduction of the mean head-shaft angle from 29° preoperatively to 11° at most recent follow-up (p<0.0001). Harris Hip Score (HHS): 24 patients had an excellent, 3 a good, 2 a fair and 1 a poor outcome defined by HHS. Remodelling: At most recent follow-up 25 patients achieved complete remodelling. The remodelling process took place especially during the first postoperative year.Angle alpha: The mean angle alpha of the affected hips at most recent follow-up was 62°.

CONCLUSIONS

Transfixation with Kirschner wires leads to very good clinical, functional and radiologic results with a low complication rate. Furthermore the femoral head-neck junction retains enough plasticity for an active remodelling process.

Transtrochanteric rotational osteotomy for avascular necrosis of the femoral head after unstable slipped capital femoral epiphysis: 10-year clinical results

BACKGROUND

Avascular necrosis of the femoral head (AVN) is the most serious complication after unstable slipped capital femoral epiphysis (SCFE), and is often unsalvageable. We report a minimum 10 years of clinical results for transtrochanteric rotational osteotomy of the femoral head (TRO) for AVN.

METHODS

This study included 7 patients (7 hips) with a mean age at surgery of 13.3 years, and the follow-up period was 15.8 years. All patients had prior treatment via closed reduction and pinning of the unstable SCFE, and showed severely collapsed femoral heads. The direction of rotation was anterior in 3 hips and posterior in 4. The Merle d'Aubigné-Postel score (MDPS) was used for clinical assessment, and joint degeneration was assessed with the Kellgren and Lawrence classification (KL-grade).

RESULTS

The spherical intact area of the femoral head was moved to the weight-bearing portion, and subluxation was corrected via rotation combined with intentional varus positioning. The mean MDPS improved from 10.3 points to 15.6 points at 5 years, and it was maintained at 15.0 points by 10 years; 3 hips were excellent, 1 was good, 2 were fair, and 1 showed poor outcomes. No patient experienced re-collapse after TRO or required conversion to hip replacement or arthrodesis. After 10 years, degenerative changes became evident over time, and 2 hips progressed to KL-4 with a decreased MDPS.

CONCLUSIONS

Although some joint degeneration is inevitable in the long-term, TRO is an effective salvage procedure for treating AVN after unstable SCFE.

Current concepts in management of slipped capital femoral epiphysis

Slipped capital femoral epiphysis (SCFE) is a common hip condition that can be disabling. In this review, we provide an orientation on current trends in the clinical management of SCFE including conventional procedures and specialised surgical developments. Different methods of fixation of the epiphysis, risks of complications, and the rationale of addressing deformity, primarily or secondarily, are presented. Although improved understanding of the anatomy, vascularity and implications of residual deformity have changed management strategies, the best modality of treatment that would restore complete vascularity to the femoral head and prevent any residual deformity, impingement and early osteoarthritis remains elusive.

Anterior minimally invasive subcapital osteotomy without hip dislocation for slipped capital femoral epiphysis

PURPOSE

A minimally invasive anterior approach appears to be an attractive alternative to achieve capital realignment without violating femoral head vascular supply and avoiding hip dislocation in slipped capital femoral epiphysis. The aim of this study was to detail the technical steps of subcapital realignment through a minimally invasive anterior approach and to report the preliminary results of this procedure in a prospective cohort of patients with stable slips.

METHODS

Nine patients underwent subcapital cuneiform wedge resection through a minimally invasive anterior approach without hip dislocation for moderate or severe stable slips between April 2012 and April 2013. Prophylactic stabilization of the contralateral hip was performed in all cases. A minimum 18 months follow-up was available. Clinical course was assessed using the Harris hip score and the hip range of motion. The degree of slippage as proposed by Southwick, the lateral α angle and the epiphyseal-metaphyseal distance allowed radiographic assessment.

RESULTS

No patients were lost during follow-up, which was on average 28 months. No intraoperative complications occurred; one postoperative transient apraxia of the femoral cutaneous nerve, which completely recovered in six months, was recorded. Southwick angle, lateral α angle and epiphyseal-metaphyseal distance all improved substantially postoperatively. No cases of avascular necrosis were detected.

CONCLUSION

Subcapital cuneiform wedge resection through a minimally invasive anterior approach without hip dislocation can be an easier alternative to restore proximal femoral anatomy in moderate to severe stable slips. Prospective case control studies are required to confirm these preliminary results.