[Humeral lengthening with a monolateral external fixator in achondroplasia]

In achondroplasia patients the shortening of upper limb (mainly the arms) is an important part of pathology in addition to low stature. Not all patients who are treated for increasing their height decided to have humeral lengthening and the indication for treatment is not only for cosmetic, psychological aspects but also limitation of upper limb function like self-services and personal hygiene.

5 patients were evaluated (4 girls and 1 boy) at age of 14 to 18 years (mean 15.7) in whom 10 humeral lengthening were do-ne using monolateral external fixator "Pumed". All patients have lower limb lengthening with the Ilizarov method 4-5 years before humeral lengthening. Observation time was 6 to 34 months (mean 20). In all cases the Pumed external fixator was fixed to humerus by 4 Schanz screws, open humeral distraction osteotomy was done below the insertion of deltoid muscle. In one case 15 degrees anteflexion correction was done intraoperatively. Distraction began at 5-6th day postoperatively with rate of 1 mm/day. Because of hypertrophic bone regenerate the distraction rate was often increased up to 1.5 mm/day.

8 to 9 cm lengthening was achieved (mean 8.5) which represents more than 50% of the primary segmental length. The average time of fixator application was 7 months and the lengthening index ranged from 0.8 to 1.1 months/cm (average 0.85). No shoulder and elbow joint range of motion deterioration was observed. At the follow-up transient radial nerve palsy was observed in one case after acute limb axis correction.

Humerus lengthening, in achondroplasia patients with the use of monolateral external fixator is an effective and reliable method of treatment, with relatively low lengthening index. Monolateral External Fixator are well tolerated by patients.