Summary

Humeral lengthening by callotasis using external fixation is a valuable option to improve quality of life in achondroplastic patients

Abstract

Purpose

To analyze the long-term results of humeral lengthening in achondroplastic patients and make suggestions on the most appropriate surgical technique to improve patient outcomes.

Methods

Fifty-four humeral lengthening procedures performed in twenty-seven achondroplastic patients were reviewed.
Inclusion criteria were: achondroplastic patients under 17 years-old without prior arm operations with a minimum follow-up of 36 months.
Surgical technique: The osteotomy was carried out at the proximal metaphysis of the humerus through a sub-pectoral approach. Elongations were performed by means of callotasis with unilateral external fixation using Monorail LRS (Orthofix). Distraction began without delay the day after the procedure, at a rate of 0.5 mm every 12 hours (1 mm/day). Patients were followed up with periodic radiographs to confirm that the lengthened segment (regenerate) was fully consolidated.

Results

Fifty humeri in twenty-five patients (13 males and 12 females), aged between 9 and 17-years-old, met the inclusion criteria. Mean humeral lengthening was 8.82 cm (7.5-10.5), which represented an elongation of 54.80% (46-63) of the original length. The healing index was 0.91 months (0.72-1.4) per centimeter gained. Shoulder and elbow range of motion and stability were preserved in 47 limbs. Non-complicated cases consistently experienced a significant functional improvement in the performance of activities of daily living such as putting on footwear and personal hygiene. Short-term complications included 11 pin tract infections, 1 radial nerve neurapraxia and 1 failure of the regenerated bone formation. None of these complications prevented from completion of treatment. Long-term complications included two cases of non-union, three elbow flexion contractures and two cases of psychological dissatisfaction, all of them in 4 patients. Factors associated with long-term complications were intraoperative fragment displacement and distal humeral osteotomy. No fractures of the regenerated bone were identified in the long term.

Conclusions

Callotasis with unilateral external fixation is a reliable and well-tolerated procedure for humeral lengthening in achondroplastic patients, with an acceptable complication rate. Guided fixator placement and a proximal humeral osteotomy are strongly recommended technical tips as they may help prevent complications and improve outcomes.