Surgical treatment for brachymetacarpia aims to correct the deformity via lengthening of the affected metacarpal. There are currently two surgical techniques for correcting brachymetacarpia: acute and gradual lengthening. Acute lengthening uses a bone graft and is only preferred if the required lengthening is less than 1 cm. For length discrepancies greater than 1 cm, gradual lengthening is preferred.
During gradual lengthening the metacarpal bone is separated with an osteotome and a specialized mini external fixator is applied with pins attached to the bone and connected to the fixator. The pins must be placed along the axis of the metacarpal and parallel to each other, to ensure the finger lengthens in the proper direction.
The external fixator gradually pulls the two segments of the metacarpal apart at a very slow rate (0.5 mm per day), which stimulates new bone to form in the gap. This results in increased length. The lengthening is performed until the finger is at the proper length, at which point no further modifications are made to the fixator. Prediction of required length will indicate the time required for lengthening. For example, if the metacarpal needs to be lengthened 10 mm, it will take 20 days of lengthening (based on 0.5 mm per day).
It is very important that the proper length is achieved and that the surgeon does not over-lengthen. Over-lengthening can result in joint stiffness, secondary deformities, and pain. Follow up visits are scheduled every two weeks during treatment to ensure that over-lengthening does not occur and to monitor for complications such as premature consolidation and nonunion. After the lengthening, the fixator remains until the bone consolidates. Once the bone has completely consolidated (verified via x-rays), the external fixator can be removed.