Purposes:

See if permanent damage of the growth plate after physeal distraction is the rule and

Introduction: Surgeons have always been concerned about the fate of the growth plate after physeal distraction and for that reason this technique has usually been considered only in patients nearing maturity. Previous experimental work has shown that the velocity of distraction has an influence on the viability of the growth plate at follow-up (recommended rate: 0.5 mm/day). Clinically, it has also been our observation that the condition of the physis prior to distraction is another important factor related to physeal function in the long term.

Patients and methods: Since 1987 we have used low velocity physeal distraction in 43 bone segments of which 37 cases have been followed-up at least for 24 months and this has been the group included in this study. The indications were lengthening (14), angular deformity correction (19) and resection of benign bone tumours (4). Most patients (24) were older than 10 y.o. and 22 of them were followed-up until maturity. We have retrospectively reviewed these patients looking at the radiological morphology and function of the distracted growth plate at follow-up.

Results: Out of the 24 children older than 10 y.o., twenty showed a premature complete physeal closure.

We looked with interest at the 13 cases younger than 10 y.o. since the repercussions of iatrogenic physeal damage would obviously be bigger in this age group. Five out of the 13 showed premature closure and in the remnant eight an open growth plate was observed at follow-up. All patients with open and/or functioning physes after distraction had no local injuries in the growth plate prior to distraction (4 congenital short femora and 4 normal physes). On the contrary, four out of the five cases with prematurely closed physes, had a local physeal damage prior to distraction (3 bony bridges and one non-union), and the remnant was a congenitally short femur. Growth after distraction was difficult to assess in the congenitally short femora but it has been very satisfactory in the 4 cases of previously normal physes (2 benign tumours and 2 femoral shortenings due to hip disorders). In three cases of congenital short femur in pre-teenagers we were able to repeat distraction twice through the same physis, since it had remained open after the first distraction.

Conclusions: Physeal premature closure often follows physeal distraction, but not always. The condition of the physis prior to lengthening is an important factor with influence on its viability after distraction.