We report our early experience with distracting external fixation used to offload the hip after avascular necrosis (AVN) of the femoral head secondary to severe slipped upper femoral epiphysis (SUFE). A case series of five patients treated in a tertiary centre is reported. Electronic case records and radiographs were reviewed. Data recorded included demographics, initial presentation, timing of head collapse, timing and duration of distraction and outcome including referral to adult arthoplasty services. Mean age at presentation was 12 years (range 12–15). 4 were females. Initial treatment in 4 cases was a delayed cuneiform osteotomy and pinning, one patient underwent serendipitous reduction and percutaneous pinning. Mean duration to initial surgery was 10 days (range 5–16). All patients had femoral head collapse at a mean of 148 days from time of presentation. 2 patients required backing out of screws due to intra-articular protrusion. All patients underwent distraction at a mean 193 days from presentation. Average distraction achieved was 10 mm and duration of application was 125 days (range 91–139). All patients experienced improvement or resolution of pain but persistence of poor function, characterised by fixed adduction and limb length discrepancy. 3 patients were referred to adult arthroplasty services. This may be an effective treatment option for pain associated with AVN post SUFE. However, in our experience normal anatomy and function of the hip is not restored if performed after collapse of the femoral head. Consideration should be given to application of the distractor either at the time of initial fixation or prior to femoral head collapse. Authors believe that timing of the application of the distractor is critical for a successful outcome and recommend a prospective study with large numbers

Aim. (1) To determine whether any difference exists in AVN risk between surgical reduction [Fish] or pinning-in-situ [PIS] of severe slips. (2) To review the different classifications of SUFE in relation to AVN. Materials and Methods. 56 children presented with slipped upper femoral epiphysis (SUFE) from 1998 to 2008; 29 males, 27 females; mean age 12.8 years. The Loder & Southwick classifications were used. All slips were treated surgically. The mild and moderate groups were treated with a single pin-in-situ. The severe group had either surgical reduction [Fish femoral neck osteotomy], alternatively a single pin-in-situ, randomised by day of admission. Avascular necrosis of the femoral head (AVN) was the primary outcome measurement. Results. There were seven cases of AVN (12.5%). 2/41 in the stable group developed AVN compared to 5/15 in the unstable group, statistically significant [Chi-Square P=0.001]. No patient in the mild group, one out of seven in the moderate group, and six out of 22 in the severe group developed AVN. In the severe slip group, the AVN rate in the PIS group was 40%, after Fish osteotomy it was 23.5%. This is not statistically significant, but the trend favours surgical reduction. Conclusion and Significance. (1) Surgical reduction by Fish osteotomy is no riskier for AVN than pinning in situ for severe SUFE. Surgical reduction should therefore be performed to avoid gross deformity in these cases. (2) We have confirmed that the stability and the severity of the slip at presentation are the best indicators for predicting AVN