Complications of Distraction Lengthening in the Hand

PATIENTS AND METHODS

Twenty-four metacarpals and 27 phalanges in 43 patients were lengthened between March 1996 and December 2006 using a callus distraction technique with a small external fixator (CK minifixator; Dongkwang Ltd., Korea) (Fig 1). The indications were congenital (27 patients) and traumatic deformities (17 patients). The patients’ main concern was about the appearance rather than any functional improvements that might result from lengthened and straightened rays. All patients who underwent the procedure were between the ages of 6 and 43 years (mean 30 years). Five male patients and three female patients were under the age of 14.

The planned rate of elongation was 0.25 and 0.5 mm/day for the phalanges and metacarpals, respectively. A small incision at the osteotomy level was placed to avoid the gap between the K-wires. A small periosteal flap was raised and osteotomy was performed with a fine electrical saw. A resting period of 1 week was followed by gradual lengthening. Radiographs were obtained at the beginning of the distraction, 1 week after distraction and several times thereafter. The speed of lengthening was adjusted according to the status of callus formation but was no faster than 0.5 mm/day. After achieving the desired amount of lengthening, a 2- to 3-week consolidation period was followed by pin removal and protective night splinting for 2 weeks.

The postoperative complications that occurred during the first 6 months after surgery were noted.

RESULTS

An average lengthening of 16 mm (62%) and 34 mm (63%) was obtained in the phalanges and metacarpals, respectively. The healing rates in the phalanges and metacarpals were 69 and 52 days/cm, respectively. The overall complication rate was 31% (16 of 51 patients). The major complications requiring secondary procedures were non-union (one case), fracture (one case), premature union (one case), angulation (two cases) and the dislodgment of pins (two cases). The minor complications encountered were delayed callus formation (four cases), joint stiffness (four cases) and soft tissue thinning (one case). However, complications such as infection and joint subluxation did not occur in our cases (Table 1). The post-traumatic cases had a higher incidence of complication than the congenital ones (nine out of 18 cases and seven out of 33 cases, respectively). The phalanges had a higher rate of complication than the metacarpals (11 of 27 and four of 24 complications, respectively).

Non-union occurred in an index metacarpal bone, which had a narrow medullary space after lengthening (Fig 2). A fracture occurred in a proximal phalanx in which there was an insufficient period of consolidation (Fig 2). One radial and another palmar angulation (Fig 3) occurred during the lengthening by a monofixator, which had been placed in a maloriented direction. A corrective wedge osteotomy straightened the digit. Dislodgment of pins occurred in patients aged 6 and 12 years. The distraction force applied to the K-wires caused them to cut out of the soft epiphyses (Fig 4). Delayed callus formation was observed in patients aged 29 years or older (29, 33, 36 and 43 years), whereas premature union within the first week of the resting period occurred in the middle phalanx of a 16 year-old girl (Fig 5). Under local anaesthesia, a knife was used to make an osteotomy, and an extra resting period of 3 to 5 days was used in the cases of delayed callus formation, which was followed by restarting the distraction at a slower rate than before. Joint stiffness, which was also observed in older patients, arose at either the proximal (Fig 6) or distal joints of the lengthened bone but was improved by exercises during and after the lengthening procedure. Thinning of the phalanx was observed in one case with a shortened middle phalanx but the final outcome was unknown due to the patient’s personal problems (Fig 7).

In the two children with dislodged pins, the treatment was abandoned. However, the other 12 patients with complications overcame their problems and were as satisfied with the final results as those without complications.

DISCUSSION

The gradual distraction technique first introduced by Ilizarov has made bone lengthening possible without the necessity of a bone graft (Ilizarov, 1971). However, callotasis cannot lengthen the bone by an unlimited amount, and excessive bone lengthening can cause several complications (Paley, 1990) due to the limitation in the capacity for bone formation as well as the functional and physical limitations of the surrounding soft tissue (Galardi et al., 1990; Lee et al., 1993). Distraction lengthening in the hand is done less commonly than in the lower limbs and the feet (Minguella et al., 2001; Oh et al., 2003). Although Matev (1976) reported the clinical cases in the hand only 5 years after Ilizarov’s report, there have been fewer clinical and experimental reports than for the major limbs. The lack of a suitable external fixator for the hand appears to be a major reason, especially for the phalanges (Miyawaki et al., 2002; Netscher, 1998). Most reports concern the metacarpals, which have provided limited indications for distraction lengthening (Finsen and Russwurm, 1996; Kato et al., 2002; Ogino et al., 1994). Moreover, the higher rate and severity of complications (Finsen and Russwurm, 1996; Houshian and Ipsen, 2001; Miyawaki et al., 2002) might be due to the special characteristics of the hand, which is small and mobile. The rate of complications is usually higher than for the major limbs. In our cases, the rate of major complications was 14% (7 out of 51 cases). However, the percentage lengthening was more than that used in the major limbs, for which safety guidelines have already been established. The muscles surrounding the bone facilitate bone healing (Ohashi et al., 2007). In this respect, the hands have less favourable conditions but the muscles in limb bones may also act as restraints (Lee et al., 1993). Hence, the soft tissues of the hand may be lengthened more as a result of the relatively fewer muscles. Experienced surgeons have long recognised that the compliance of the soft tissues is one of the important factors affecting both the rate and the amount of lengthening. Our experience of delayed callus formation, non-union and fracture suggests that more care needs to be taken to reduce the rate of complications in the future.

It was a mistake to perform the procedure in patients under 12 years of age. The distraction force was applied to the thin K-wires, which acted like a knife and eventually slid out of the soft immature epiphysis, which could not withstand the cutting forces (Fig 5). This situation could almost certainly be avoided by waiting until the patient was 15 years or older to allow the bone to mature.

Despite the efforts to prevent angulation, it did occur and required surgical correction (Finsen and Russwurm, 1996; Matev, 2003). This complication can be minimised by care on the part of the surgeon. Another major complication, premature union, appears to be avoidable. Since that case, the telescoping principle (0.25 mm distraction on the fifth day followed by immediate repositioning) has been used to prevent early healing and promote callus formation (Choi et al., 2000). This was usually used in patients aged between 15 and 25 years, and premature union has not been encountered since. Joint stiffness at either the proximal or distal joints of the lengthened bone has been another problem but was lessened by encouraging exercise during and after the lengthening procedure. Thinning of the soft tissue occurred in the middle of the middle phalanx, where the thinnest site was chosen as the distraction point to avoid placing the fixator across the joint (Fig 7). In this case in which there was a scarred dorsal contracture, the osteotomy had to be made as proximally as possible. Unfortunately, we do not know the final result due to the patient’s personal problems.

Infections, which have been reported in other papers (Houshian and Ipsen, 2001; Minguella et al., 2001), were not encountered in this series. It is believed that crushing of soft tissues caused by the drilling of the pins is the main reason for infection. To prevent this and avoid direct crushing trauma, separate incisions were made for bone exposure and the insertions of the pins.

Although callus distraction in the hand requires a longer treatment period and has a relatively higher rate of complication than in major limb bones, it appears to be effective in achieving adequate bone length. A high level of patient compliance and prompt management of any problems by an experienced surgeon are essential for achieving good results.