Pediatric orthopaedists have long been searching for anatomic, mechanical, and metabolic causes of slipped capital femoral epiphysis (SCFE). Adolescent obesity has been a recognized SCFE risk factor for 50 years. (Interestingly, high BMI is a consistent risk factor in males, but females who experience SCFE are often thin.) Possible racial risk factors have been examined as well, with no clear conclusions.
Because the incidence of SCFE is relatively low (1 in 10,000 children according to this JBJS Clinical Summary) and the risk of bilaterality is high (in the range of 30% to 40%), it seems likely that anatomic risk factors are at play. In the January 2, 2020 issue of The Journal, Novias et al. home in on the 3-D anatomy of the epiphyseal tubercle (a small, round protuberance thought to stabilize the epiphysis) and peripheral “cupping” of the epiphysis in patients with and without SCFE.
They found a smaller epiphyseal tubercle and more extensive epiphyseal cupping in patients with SCFE compared with normal hips. The authors encourage further investigation of the first finding to determine whether smaller tubercles are a consequence of the slip process or an anatomic variant that predisposes the epiphysis to slip.
A major strength of this study is that all measurements were made by a single observer blinded to the diagnosis of SCFE and other potentially confounding clinical and demographic data. Also, the measurement processes used in this study have been previously validated.
Investigation into the anatomic features of this disease should continue, along with development of minimally invasive, safe, and inexpensive ways to screen for possible anatomic risk factors. The most pertinent clinical goals are to continue evolving minimally invasive methods of epiphyseal stabilization to prevent and/or treat SCFE and to more accurately identify hips at risk of SCFE.
Marc Swiontkowski, MD
Up to 40% of kids who experience a slipped capital femoral epiphysis (SCFE) in one hip develop a slip in the contralateral hip. Recent research in pediatric orthopaedics has attempted to identify risk factors for a second SCFE in patients who have had a first. A retrospective study by Maranho et al. in the February 6, 2019 issue of JBJS provides additional evidence about one particular risk factor.
The authors radiographically measured the epiphyseal tilt, epiphyseal extension ratio, alpha angle, and epiphyseal angle of the uninvolved, contralateral hip among 318 patients (mean age of 12.4 years) who presented for treatment of a unilateral SCFE between 2000 and 2017. After adjusting for triradiate cartilage status, Maranho et al. found that, over a minimum follow-up of 18 months:
- Increased posterior epiphyseal tilt was associated with an increased risk of contralateral SCFE, which corroborates recent findings. Specifically, an epiphyseal tilt of >10° corresponded to a 54% predicted probability of a contralateral slip in patients with open triradiate cartilage.
- Increased epiphyseal extension around the metaphysis in the superior plane had a protective effect against a contralateral SCFE. For each 0.01 increase in superior epiphyseal extension ratio, the odds of a contralateral slip decreased by 6%.
- The alpha angle and epiphyseal angle were not independently associated with a contralateral slip.
Clinically, the authors suggest that the tilt findings may be more useful than the extension-ratio findings, especially when it comes to the difficult decision around whether to perform prophylactic percutaneous pinning of the contralateral hip. They write that “prophylactic fixation may be discussed with the families of patients presenting with unilateral SCFE who have a tilt angle of >10°,” noting that this threshold “would result in a low proportion of patients undergoing unnecessary prophylactic pinning.” Maranho et al. are quick to add that even contralateral hips with epiphyseal tilt angles <10° are at risk of SCFE and should be closely monitored.
Under one name or another, The Journal of Bone & Joint Surgery has published quality orthopaedic content spanning three centuries. In 1919, our publication was called the Journal of Orthopaedic Surgery, and the first volume of that journal was Volume 1 of what we know today as JBJS.
Thus, the 24 issues we turn out in 2018 will constitute our 100th volume. To help celebrate this milestone, throughout the year we will be spotlighting 100 of the most influential JBJS articles on OrthoBuzz, making the original content openly accessible for a limited time.
Unlike the scientific rigor of Journal content, the selection of this list was not entirely scientific. About half we picked from “JBJS Classics,” which were chosen previously by current and past JBJS Editors-in-Chief and Deputy Editors. We also selected JBJS articles that have been cited more than 1,000 times in other publications, according to Google Scholar search results. Finally, we considered “activity” on the Web of Science and The Journal’s websites.
We hope you enjoy and benefit from reading these groundbreaking articles from JBJS, as we mark our 100th volume. Here are two more:
Long-term Follow-up of Slipped Capital Femoral Epiphysis
B T Carney, S L Weinstein, J Noble: JBJS, 1991 January; 73 (5): 667
In this retrospective study of 155 hips with SCFE followed for a mean of 41 years after onset of symptoms, Carney et al. found that pinning in situ provided the best long-term function and delay of degenerative arthritis—and that realignment techniques were associated with a risk of substantial complications.
Treatment of Scoliosis: Correction and Internal Fixation by Spine Instrumentation
P R Harrington: JBJS, 1962 June; 44 (4): 591
The need for this at-the-time revolutionary instrumented approach was the polio epidemic, which left Dr. Harrington caring for many patients with severe, collapsing curves that threatened their health. Just as current hip arthroplasty techniques represent incremental improvements to the contribution of Charnley, current techniques in scoliosis surgery are stepwise improvements to Harrington’s work.
Long-term population-based research has documented associations between high BMI and decreased longevity and increased risk of developing diabetes and cardiac complications. Musculoskeletally speaking, the risk of developing osteoarthritis of the knee has been strongly associated with elevated BMI, although the impact of high BMI on the development of hip osteoarthritis has been less clearly defined.
To detail the impact of increased BMI on the developing hip, in the January 3, 2018 issue of The Journal, Novais et al. painstakingly evaluated 128 pelvic CT images from a group of adolescents presenting with abdominal pain but no prior history of hip pathology. The authors found a significant association between increasing BMI percentiles and femoral head-neck alterations, including:
- Increased alpha angle
- Reduced head-neck offset and epiphyseal extension, and
- More posteriorly tilted epiphyses.
Taken together, these morphological anomalies resemble, in the authors’ words, “a post-slip or mild slipped capital femoral epiphysis [SCFE] deformity.”
While the association between elevated body mass and the risk of SCFE has long been known, the impact of high BMI on the morphology of the “normal” hip had not, until now, been described in detail. It makes intuitive mechanical sense that Novais et al. found no impact of high BMI on acetabular anatomy, but because of the orientation of the proximal femoral growth plate, it does make sense that high BMI affects the growing femoral head-neck junction.
It is my hope that consolidating these data with the abundance of other evidence about the health risks of high BMI in growing children will further coalesce worldwide efforts to lower the intake of sugar and “empty carbs” among growing children, and will further spur investment in programs to increase physical activity among this vulnerable age group.
Marc Swiontkowski, MD
The multifactorial pathogenesis of slipped capital femoral epiphysis (SCFE) almost certainly involves the acetabulum, but previous studies about that relationship have been inconclusive. In the June 21, 2017 issue of JBJS, Hesper et al. report on a matched-cohort study that used precise measurements gleaned from CT to determine that acetabular retroversion—not acetabular depth or overcoverage of the femoral head—is associated with SCFE.
The authors carefully measured acetabular depth, head coverage, and retroversion in three groups of hips: the affected hips of 36 patients with unilateral SCFE, the unaffected contralateral hips of those same patients, and healthy hips of 36 age- and sex-matched controls. They observed no deep acetabula or acetabular overcoverage in the SCFE-affected hips, but they did find a lower mean value for acetabular version (i.e., retroversion) at the level of the femoral-head center in the SCFE-affected hips, relative to contralateral and control hips. The acetabulum was retroverted cranially in cases of severe SCFE compared with mild and moderate cases.
These findings support the hypothesis that SCFE-affected hips have reduced acetabular version, but the authors note that “additional studies will be necessary to determine whether acetabular retroversion is a primary morphological abnormality associated with the mechanical etiology of SCFE, or if it is an adaptive response to the acetabulum after the slip.” Either way, Hesper et al. conclude that their data “may help with planning treatment for patients with residual pain and limited motion related to femoroacetabular impingement after SCFE.
Every month, JBJS publishes a Specialty Update—a review of the most pertinent and impactful studies published in the orthopaedic literature during the previous year in 13 subspecialties. Click here for a collection of all OrthoBuzz Specialty Update summaries.
This month, Derek Kelly, MD, co-author of the February 15, 2017 Specialty Update on Pediatric Orthopaedics, selected the five most clinically compelling findings from among the 60 studies summarized in the Specialty Update.
—A systematic review of eight randomized studies comparing splinting with casting for distal radial buckle fractures confirmed that splinting was superior in function, cost, and convenience, without an increased complication rate.1
—A review of the treatment of 361 pediatric diaphyseal femoral fractures before and after the 2009 publication of AAOS clinical guidelines for treating such fractures revealed that the guidance had little impact on the treatment algorithm in one pediatric hospital.
—Bracing remains an integral part of managing adolescent idiopathic scoliosis, but patient compliance with brace wear is variable. A prospective study of 220 patients demonstrated that physician counseling based on compliance-monitoring data from sensors embedded in the brace improved patients’ average daily orthotic use.
—AAOS-published evidence-based guidelines on the detection and nonoperative management of developmental dysplasia of the hip (DDH) in infants from birth to 6 months of age determined that only two of nine recommendations gleaned from evidence in existing literature could be rated as “moderate” in strength:
- Universal DDH screening of all newborn infants is not supported.
- Imaging before 6 months is supported if the infant has one or more of three listed risk factors.
Seven additional recommendations received only “limited” strength of support.
—A study of the utility of inserting an intraoperative intracranial pressure (ICP) monitor during closed reduction and pinning for slipped capital femoral epiphysis (SCFE) found that 6 of 15 unstable hips had no perfusion according to ICP monitoring. However, all 6 hips were subsequently reperfused with percutaneous capsular decompression, and no osteonecrosis developed over the next 2 years.
- Hill CE, Masters JP, Perry DC. A systematic review of alternative splinting versus complete plaster casts for the management of childhood buckle fractures of the wrist. J Pediatr Orthop B. 2016 ;25(2):183–90.
Osteonecrosis of the femoral head is a dreaded complication for patients with a slipped capital femoral epiphysis (SCFE). This complication is far more common with acutely displaced and unstable slips. Safely reducing the femoral head back on the neck while preserving blood supply can often be accomplished with closed reduction maintained by in situ cannulated screw fixation, although some recent efforts to treat SCFE have focused on open approaches.
In the June 15, 2016 edition of The Journal, Schrader et al. demonstrate the benefits of using a simple intracranial pressure (ICP) monitoring probe (see photo) inserted through the cannulated screw to measure femoral head perfusion. While using this technique intraoperatively on 26 hips with SCFE, the authors encountered six hips in which there was no blood flow to the femoral head after closed reduction and screw stabilization. In these situations, they performed percutaneous capsular decompression.
The fact that all patients—even those with no initial femoral head perfusion—left the operating room with measurable blood flow confirms the long-held principle that lack of perfusion can be treated with capsulotomy. The ICP device uses waveforms to measure blood flow and is an accurate gauge of perfusion. Moreover, the technology is available in most hospitals with trauma centers or neurosurgery services.
Having researched femoral head perfusion myself as a young orthopaedist and having kept abreast of more recent findings in this area, I think the monitoring protocol described by Schrader et al. is the best yet published to limit the devastating complication of hip osteonecrosis. I feel that if ICP monitors are available, this protocol should be adopted by all centers treating patients with acute SCFE.
Marc Swiontkowski, MD