Prophylactic pinning of the contralateral hip in unilateral Slipped Upper Femoral Epiphysis (SUFE) persists as a source of debate with the majority of surgeons selecting this option in a proportion of patients whom they regard as at increased risk of a subsequent slip.

Universal prophylactic pinning was introduced in our region in 2005 after an audit of ten years local practice identified 25% of unilateral cases presented with a subsequent slip. This study reports our experience between 2005 and 2020.

In this prospective study, 44 patients presented with 55 affected hips compared with 60 patients with 67 affected hips in the original study. Two patients were excluded as their initial slip had not been treated in our unit. Of the 42 hips seven were bilateral, 34 of the 35 unilateral hips underwent prophylactic pinning. The one exception subsequently underwent prophylactic pinning due to developing pain.

Consistent with our original series, at a minimum follow up of 13 months there have been no complications of infection, fracture, chondrolysis or avascular necrosis subsequent to prophylactic pinning.

Over 25 years 70 patients have undergone prophylactic pinning without complication. On the premise that 25% of our unpinned hips presented with subsequent slips before instituting our policy we estimate that we have prevented 17 subsequent slips over 25 years including the consequences which can be significant. We continue to advocate universal prophylactic pinning as an effective and safe practice in the management of SUFE.

Prophylactic fixation of the contralateral hip in cases of unilateral slipped capital femoral epiphysis (SCFE) remains contentious. Our senior author reported a 10 year series in 2006 that identified a rate of subsequent contralateral slip of 25percnt; when prophylactic fixation was not performed. This led to a change in local practice and employment of prophylactic fixation as standard. We report the 10 year outcomes following this change in practice.

A prospective study of all patients who presented with diagnosis of SCFE between 2004 and 2014 in our region. Intra-operative complication and post-operative complication were the primary outcomes. 31 patients presented during the study period: 16 male patients and 15 female patients. The mean age was 12.16 (8–16, SD 2.07). 25 patients had stable SCFE and 5 had unstable SCFE. Stability was uncertain in 1 patient. 25 patients had unilateral SCFE and 6 had bilateral SCFE. 24 patients who had unilateral SUFE had contralateral pinning performed. 1 unilateral SCFE did not have contralateral pinning performed as there was partial fusion of physis on contralateral side.

In the hips fixed prophylactically there was 1 cases of transient intraoperative screw penetration into the joint and 1 case of minor wound dehiscence. There were no cases or chondrolysis or AVN. There were no further contralateral slips. This change in practice has been adopted with minimal complication. The fixation of the contralateral side is not without risk but by adopting this model the risk of subsequent slip has been reduced from 25percnt; to 0percnt;.

Prophylactic pinning of the contralateral hip in the treatment of slipped upper femoral epiphysis has been shown to be safer than continued observation of the contralateral hip. This treatment remains controversial due to the potential for harm caused to an apparently unaffected hip. There is evidence that pinning of an already slipped epiphysis causes growth disturbance of the proximal femur, however Hagglund showed that there is not necessarily growth arrest at the physis after pinning, as the slip occurs at the hypertrophic layer of the growth plate with no damage to the germative layer. This was confirmed by Guzzanti who confirmed that a single screw provided epiphyseal stability and preserved potential for growth. We conducted a pilot study to determine whether prophylactic pinning affects subsequent growth of the unaffected hip.

In order to determine the effect of prophylactic pinning we compared radiographs skeletally mature patients who had either undergone the procedure (group 1), not undergone the procedure but had pinning of the affected side (group 2), and adults with no history of SUFE (group 3). We measured the articulo-trochanteric distance and calculated the ratio of the trochanteric-trochanteric distance to articulo-trochanteric distance. These measures have been used in previous studies and shown to be reliable indicators of disturbed proximal femoral growth. As this was a pilot study we recruited 8 to each group.

The absolute sum of the ATDs were 219mm (average 27.3mm) Group 1, 213mm (average 26.6mm) Group2 and 258mm (average 32.5mm). The average trochanter-trochanter: ATD ratio in group 1 was 2.7 (1.9 - 3.8) compared to 2.7 (2.3 - 3.2) and 2.3 (1.9 - 2.7) in groups 2 and 3 respectively.

Our results suggest no difference in subsequent growth between hips that are prophylactically pinned and those that are not. They also show that unpinned hips go on to grow abnormally when compared to normal hips suggesting perhaps sub-clinical SUFE.

These results have prompted expansion of the study to include much a higher number of patients.