Does humeral lengthening with a monolateral frame improve function?
Humeral lengthening by distraction osteogenesis historically has relied on bulky circular external fixators. Advances in fixator technology have allowed for the use of monolateral frames. However, it is unclear whether and to what degree function is improved after humeral lengthening.
We asked: (1) Does humeral lengthening performed with monolateral fixators improve function? (2) Does monolateral external fixation produce comparable restoration of length and complication rate when compared with historical results, using circular external fixation for humeral lengthening?
We retrospectively reviewed 11 patients who underwent 15 humeral lengthenings with monolateral external fixation. Clinical and radiographic data were collected, including preoperative and postoperative DASH scores as a metric of functional status. The minimum postremoval followup was 14 months (average, 38 months; range, 14-84 months).
Fifteen humeri were lengthened an average of 7 cm (range, 4-9 cm), for a mean lengthening of 41% (range, 23%-52%). Lengthening required an average of 7 months (range, 5-8 months) of fixation, resulting in an external fixation index of 32 days/cm (range, 23-45 days/cm). The major complication rate (three of 15) and postoperative ROM (unchanged at the elbow and improved in seven of 15 shoulders) were comparable to those in previous studies using circular frames. In nine of 15 humeri for which DASH scores were available, the mean preoperative score improved from 14 to 9 after 1 year. The monolateral frame allowed the patient to keep their arm by the side without abducting the shoulder and without impinging the device into the chest wall.
Humeral lengthening with monolateral external fixation is well tolerated by patients and an effective means of improving patient function with a complication rate similar to that for traditional circular frames.