Outcome of the modified Dunn procedure in severe chronic or acute on chronic slipped capital femoral epiphysis

Abstract

BackgroundIn recent years, the modified Dunn osteotomy has gained popularity to treat slipped capital femoral epiphysis (SCFE) with various complication rates. Most studies included patients with different severities. This study aimed to determine (1) the radiological and clinical outcome, (2) the health-related quality of life, and (3) the incidence of avascular necrosis of the femoral head (AVN) in patients with severe chronic or acute on chronic SCFE treated by the modified Dunn procedure.MethodsOut of 150 patients with SCFE treated at our institution between 2001 and 2014, 15 patients (mean age 12.9 years (range 11.8–15)) were treated by the modified Dunn procedure. Eight SCFE were chronic and 7 acute on chronic. All slips were severe with a mean Southwick slip angle (SSA) of 67° (range 60–80). Radiographic and clinical outcomes were measured. Mean time of follow-up was 3.8 years (range 1–10).ResultsAnatomical reduction was achieved in all cases. Good radiological results according to the Stulberg Classification (grade 1 + 2) and the Sphericity Deviation Score (< 30) were found in 9 out of 13 patients at the last follow-up. Clinical and functional outcome analysis revealed good results in 8 out of 10 patients (Harris Hip Score > 80). The quality of life measured by the Nottingham Health Profile (NHP) was described good in 10 out of 10 patients. Four out of 15 patients developed an AVN.ConclusionsThe modified Dunn procedure has a great potential to restore proximal femur geometry in severe chronic or acute on chronic SCFE. It should be considered only if there is no other possibility to restore proximal femur geometry, as is the case in severe slips, due to the risk of AVN.

Surgical treatment of slipped capital femoral epiphysis (SCFE) by Dunn procedure modified by Ganz: a systematic review

“… Zuo et al, J Orthop Surg Res, 2020 [ 36 ](Retrospective) 21 13.2 y 20/1 1/20/0 0/0/21 2.6 y Average HHS: 96.7; WOMAC: 95.4 0% Implant failure: 4.8%; Procedure technically demanding but safe and extremely valuable for restoring hip anatomy and preserving function in severe SCFE. Ebert et al, J Orthop Surg Res, 2019 [ 35 ] (Retrospective) 15 12.9 y 15/0 0/8/7 0/0/15 3.8 y Average HHS: 85.7; NHP: 0.91; VAS: 1.6; SDC: 27.8 26.7% Hip subluxation: 13.3%; implant failure caused by AVN: 13.3% Satisfactory results in most patients but, considering the risk of complications, the procedure is only indicated in severe chronic or acute on chronic SCFE. Davis et al, JPO, 2019 [ 34 ] (Retrospective) 48 13.8 y (stable) 12.5 y (unstable) 17/31 31/17/0 N/A 2.9 y (stable), 2.3 y (unstable) No data are reported regarding the final results except complications 29.4% (stable), 6.4% (unstable) Hip subluxation: 17.6% (stable); Heterotopic ossification: 9.7% (unstable), 5.9% (stable); Hardware removal: 12.9% (unstable), 29.4% (stable) Effective procedure in stable and unstable hips.…”

“…On the contrary, in moderate and severe forms of SCFE, there is a high risk of degenerative joint disease caused by the consequent deformity of the femoral head. Therefore, a surgical correction by anatomical repositioning of the capital epiphysis on the femoral neck, should be the treatment of choice, even with an incidence of AVN > 20% [ 21 – 23 , 28 , 30 , 31 , 33 – 35 ]. Dunn osteotomy performed with Ganz approach represents the only surgical procedure for restoring the correct anatomy of the proximal part of the femur without stretching the retinaculum vessels, however the operation is still technically demanding.…”

“…Dunn osteotomy performed with Ganz approach represents the only surgical procedure for restoring the correct anatomy of the proximal part of the femur without stretching the retinaculum vessels, however the operation is still technically demanding. The majority of the studies in spite of a high rate of AVN, are in favor of this procedure, although there is disagreement regarding the indications in relation to the type of SCFE [ 21 – 23 , 30 , 31 , 34 , 35 ]. Davis et al [ 34 ], reported better results in unstable hips in which the AVN rate was 6.4% in comparison to 29.4% observed in stable hips.…”

“…The incidence of implant removal ranged from 2.3 to 29.48%. In five papers [ 23 , 34 , 35 , 37 , 38 ] the authors observed hip instability with an incidence from 3.3 to 17.6% that required a second operation. This complication, as reported by some authors [ 42 ] may be directly related to SCFE such as damages of the acetabular labrum or the acetabular cartilage, causes not related to SCFE (acetabular orientation or poor quality of the soft tissues) and causes related to the surgical operation.…”

“…They observed most frequent complications in stable hips (AVN: 29.4% vs 6.4%, hip instability: 13.3% vs 0%), but they concluded that, although the complications are higher in stable hips, the surgical procedure is effective in both groups. Six papers [ 24 – 26 , 28 , 33 , 35 ] reported only patients with stable hips (123 hips), three of them had an incidence of AVN > 20%, while the other three, a low incidence. The remaining three papers [ 21 , 29 , 31 ] reported only patients with unstable hips (85 hips), with a high incidence of AVN in two studies (about 26%).…”