Persisting growth after prophylactic single-screw epiphysiodesis in upper femoral epiphysis

Does Prophylactic Pinning Affect the Proximal Femur Morphology in Slipped Capital Femoral Epiphysis?

Background

The role of prophylactic pinning of the contralateral hip in unilateral SCFE is well established in patients with risk factors for developing contralateral slip. The effect of prophylactic pinning on the growth and morphology of the hip is not well documented in the literature. We aimed to study the effect of prophylactic pinning on the residual growth and morphology of the proximal femur.

Materials & Methods

The institutional database was searched for all unilateral SCFE cases for the period 2011 to 2020. A total of 171 unilateral SCFE cases were identified. All the radiographs were scanned and those patients who had follow-up X-rays till skeletal maturity were included in the study. Prophylactic pinning was performed using 6.5 mm fully threaded cancellous screws in supine position on a radiolucent table. The following radiological parameters were measured on the post-operative X-rays and at skeletal maturity: (i) neck length (NL), (ii) neck-shaft angle (NSA), (iii) femoral offset (FO), (iv) articulo-trochanteric distance (ATD) and (iv) tip-apex distance (TAD) by two different observers.

Results

The mean age of the cohort was 13.7 years. ATD decreased from the mean value of 25.67 mm in post-operative radiographs to 20.84 mm in final follow-up radiographs. The NL, FO, and TAD were found to be increasing with age with mean final follow-up values of 55.35 mm, 41.41 mm, and 6.19 mm respectively compared to post-operative mean values of 50.95 mm, 37.4 mm, and 4.69 mm. There was no significant change in the neck-shaft angle. The mean post-operative NSA was 132.9° and it was 131.8° at final follow-up radiographs.

Conclusion

Prophylactic pinning in unilateral SCFE does not stop the growth of the proximal femur completely. The ATD decreases in all the patients with prophylactic screw fixation probably due to the discrepancy in growth between the trochanteric apophysis and proximal femoral physis. The clinical effects of this subtle change in the morphology of the proximal femur need further investigation.

Level of Evidence

Level IV Case series.

Prophylactic fixation of the unaffected contralateral side in children with slipped capital femoral epiphysis seems favorable: A systematic review

BACKGROUND

Slipped capital femoral epiphysis (SCFE) occurs in adolescents and has an incidence of around 10 per 100000 children. Children presenting with a unilateral SCFE are 2335 times more likely to develop a contralateral SCFE than the general population. Prognostic factors that have been suggested to increase the risk of contralateral slip include a younger patient, an underlying endocrine disorder, growth hormone use and a higher radiographic posterior sloping angle. However, there is still much debate on the advantages and disadvantages of prophylactic fixation of the unaffected side in an otherwise healthy patient.

AIM

To investigate the risk rate of contralateral SCFE and assess the (dis)advantages of prophylactic fixation of the contralateral hip.

METHODS

A systematic literature search was performed in the Embase, Medline, Web of Science Core Collection and Cochrane databases. Search terms included ‘slipped capital femoral epiphysis,’ ‘fixation,’ ‘contralateral,’ and derivatives. The eligibility of the acquired articles was independently assessed by the authors and additional relevant articles were included through cross-referencing. Publications were considered eligible for inclusion if they presented data about otherwise healthy children with primarily unilateral SCFE and the outcomes of prophylactically pinning their unaffected side, or about the rates of contralateral slips and complications thereof. The study quality of the included articles was assessed independently by the authors by means of the methodological index for non-randomized studies criteria.

RESULTS

Of 293 identified unique publications, we included 26 studies with a total of 12897 patients. 1762 patients (14%) developed a subsequent symptomatic contralateral slip. In addition, 38% of patients developed a subsequent slip on the contralateral side without experiencing clinical symptoms. The most outspoken advantage of prophylactic fixation of the contralateral hip in the literature is prevention of an (asymptomatic) slip, thus reducing the increased risk of avascular necrosis (AVN), cam morphology and osteoarthritis. Disadvantages include an increased risk of infection, AVN, peri-implant fractures, loss of fixation as well as migration of hardware and morphologic changes as a consequence of growth guidance. These risks, however, appeared to only occur incidentally and were usually mild compared to the risks involved with an actual SCFE.

CONCLUSION

The advantages of prophylactic pinning of the unaffected side in otherwise healthy patients with unilateral SCFE seem to outweigh the disadvantages. The final decision for treatment remains to be patient-tailored.

Is there a persistent capital femoral epiphysis growth after screw fixation for slipped capital femoral epiphysis?

Femoral neck screwing during child development is controversial. The objective of this study was to evaluate the residual growth of the capital femoral physis after screw fixation. This retrospective study included children aged younger than 12 years treated for slipped capital femoral epiphysis (SCFE) with a single percutaneous partially threaded cannulated screw. The children were followed up for at least 1 year. Some patients also underwent prophylactic contralateral screwing. Preoperative, immediate postoperative and final follow-up X-rays were evaluated to determine the degree of slippage, pin–joint ratio (PJR), neck–pin ratio (NPR), number of threads crossing the physis, neck–shaft angle (NSA), screw–physis angle and screw position in the physis. We included 17 patients (29 hips: 18 SCFE and 11 prophylactic) with a mean age of 10.1 years (range: 7.1–11.9 years) at the time of surgery. Significant evolution of radiological growth parameters of the proximal femoral physis was noted during a mean follow-up of 2.4 years (range: 1–4.3 years). The mean PJR significantly decreased from 7.3 to 6.0, the mean NPR significantly decreased from 106 to 96 and the mean number of threads beyond the physis decreased from 3.3 to 1.8. The mean NSA decreased by 6.5°, from 139° to 132.5°. Persistent capital femoral epiphysis growth occurs after screw fixation. The NSA significantly decreases over time but remains within the physiological limits.

Level of evidence: IV (case series)

Safely Reducing the Incidence of Contralateral Slipped Capital Femoral Epiphysis: Results of a Prospectively Implemented Prophylactic Fixation Protocol Using the Posterior Sloping Angle

BACKGROUND

Bilateral slipped capital femoral epiphysis (SCFE) is common. The management of the contralateral hip in unilateral SCFE remains controversial. The aim of this study was to report on the clinical outcomes using a posterior sloping angle (PSA) threshold of 14.5 degrees for prophylactic fixation in preventing contralateral SCFE.

METHODS

Having previously established through a retrospective study that PSA was predictive of future slip, the authors put in place a protocol where patients with unilateral SCFE who had a PSA ≥14.5 degrees on the contralateral side were offered prophylactic fixation. Those with unilateral SCFE presenting between January 2008 and December 2018 with a minimum of 12-month follow-up were included. Patients with renal or endocrine disorders were excluded. Primary outcomes were the number of slips prevented, the number needed to treat, and the complication rate.

RESULTS

Of the 219 patients who were included, 114 (52.1%) underwent prophylactic fixation.A PSA threshold of 14.5 degrees prevented 77% of subsequent slips with a number needed to treat of 2.4 in our population. There were no cases of chondrolysis, avascular necrosis, or periprosthetic fracture associated with prophylactic pinning.

CONCLUSIONS

Prophylactic fixation using a PSA of 14.5 degrees is safe, decreases unnecessary intervention, and reduces 77% of subsequent SCFE. The PSA can increase over time and the authors recommend that the protocol be applied for the duration of follow-up.

LEVEL OF EVIDENCE

Level III.

Arthroscopic osteochondroplasty in patients with mild slipped capital femoral epiphysis after in situ fixation

PURPOSE

Mild slipped capital femoral epiphyses (SCFE) nevertheless show significant femoral head-neck deformities which may put cartilage and acetabular labrum at risk. Whether this deformity can be restored to normal has not yet been described in the literature.

METHODS

In a prospective follow-up study, 14 patients with mild SCFE underwent in situ fixation with a single 6.5-mm cancellous, partially threaded screw. In 14 patients arthroscopic osteochondroplasty was performed, and in 13 patients pre- and postoperative measurements of the α-angle were made using antero-superior radial magnetic resonance imaging.

RESULTS

After arthroscopic osteochondroplasty, the mean α-angle decreased from 57° (range 50°-74°) to 37° (range 32°-47°; p < 0.001). Six patients showed beginning degenerative intra-articular changes (four antero-superior cartilage and three antero-superior labrum lesions) at the time of hip arthroscopy. No intra-operative complications occurred. In one patient, arthroscopic debridement was necessary due to arthrofibrosis and persistent pain.

CONCLUSION

Arthroscopic osteochondroplasty can successfully correct the antero-superior α-angle in patients with mild SCFE to normal values. Clinical randomized controlled studies with long-term follow-up are required to find evidence of improved functional and radiographic mid- and long-term outcome compared to in situ fixation alone.