Continued growth after fixation of slipped capital femoral epiphysis.
OBJECTIVE
When treating slipped capital femoral epiphysis (SCFE), a smooth pin with a hook or a short threaded screw can be used to allow further growth, which could be important to prevent the development of impingement and early arthritis. The purpose of this investigation was to measure growth in three dimensions after fixation of SCFE.


METHODS
Sixteen participants with unilateral SCFE, nine girls and seven boys with a median age of 12.0 years (range 8.4-15.7 years), were included. The slipped hip was fixed with a smooth pin with a hook, and the non-slipped hip was prophylactically pinned. At the time of surgery, tantalum markers were installed bilaterally on each side of the growth plate through the drilled hole for the pin. Examination with radiostereometric analysis (RSA) was performed postoperatively and at 3, 6 and 12 months. The position of the epiphysis in relation to the metaphysis was calculated.


RESULTS
At 12 months, the epiphysis moved caudally, median 0.16 mm and posteriorly 2.28 mm on the slipped side, in comparison to 2.28 cranially and 0.91 mm posteriorly on the non-slipped side, p = 0.003 and p = 0.030, respectively. Both slipped and non-slipped epiphysis moved medially, 1.52 and 1.74 mm, respectively. A marked variation in the movement was noted, especially on the slipped side.


CONCLUSIONS
The epiphysis moved in relation to the metaphysis after smooth pin fixation, both on the slipped side and on the prophylactically fixed non-slipped side, implying further growth. The RSA method can be used to understand remodelling after 'growth-sparing' fixation of SCFE.
Department of Orthopaedics, Skaraborg Hospital, 541 85, Skövde, Sweden.|Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
Per
P
Holmdahl
Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.|Department of Paediatric Surgery, The Queen Silvia Children's Hospital, Sahlgrenska University Hospital, Gothenburg, Sweden.
Torsten
T
Backteman
Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.|Department of Orthopaedics, Sahlgrenska University Hospital, Gothenburg, Sweden.
Aina
A
Danielsson
Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.|Department of Orthopaedics, Sahlgrenska University Hospital, Gothenburg, Sweden.
Johan
J
Kärrholm
Department of Orthopaedics, Skaraborg Hospital, 541 85, Skövde, Sweden. Jacques.riad@vgregion.se.|Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden. Jacques.riad@vgregion.se.
Jacques
J
Riad
Growth; Impingement; Osteoarthritis; Radiostereometric analysis; Remodelling; Slipped capital femoral epiphysis