We have compared, in rabbits, two techniques of limb lengthening by distraction of the epiphyseal plate using a unilateral external fixation frame. In all cases, 14 mm of symmetrical lengthening without deviation was achieved. With rapid distraction at rates of 1 mm per day (distractional epiphyseolysis) separation of the epiphysis from the metaphysis occurred by day 7, and by day 70 almost complete ossification of the cartilage and the elongated segment was evident. In contrast, slow distraction at 0.25 mm every 12 hours (chondrodiatasis) produced hyperplasia of growth cartilage without any evidence of detachment at 28 days, the end of the distraction period. By day 70 the epiphyseal plate had returned to normal thickness with normal cellular morphology, while the lengthened segment was occupied by ossified tissue. The significance of these findings is discussed

There are many operations for hallux valgus and hallux rigidus, but Keller's operation remains one of the most popular, particularly for the older patient. A prospective trial was carried out to compare the results of Keller's operation modified by Kirschner-wire distraction with those of the standard operation. The results suggest that there is no advantage in using temporary Kirschner-wire distraction; indeed, degenerative changes in the interphalangeal joint and a subjectively worse result may result from its use

We applied joint distraction using an Ilizarov apparatus in 11 patients with post-traumatic osteoarthritis of the ankle to try to delay the need for an arthrodesis. Distraction for three months resulted in clinical improvement in pain and mobility for a mean of two years, with an increase in the joint space. We considered that these effects may be produced by the absence of mechanical stress on the cartilage combined with the intra-articular hydrostatic pressures during distraction. We measured these pressures during walking with distraction, and found levels very similar to those reported to improve osteoarthritic cartilage when applied in vitro

We have previously shown that joint distraction and movement with a hinged external fixation device for 12 weeks was useful for repairing a large articular cartilage defect in a rabbit model. We have now investigated the results after six months and one year. The device was applied to 16 rabbits who underwent resection of the articular cartilage and subchondral bone from the entire tibial plateau. In group A (nine rabbits) the device was applied for six months. In group B (seven rabbits) it was in place for six months, after which it was removed and the animals were allowed to move freely for an additional six months. The cartilage remained sound in all rabbits. The areas of type II collagen-positive staining and repaired soft tissue were larger in group B than in group A. These findings provide evidence of long-term persistence of repaired cartilage with this technique and that weight-bearing has a positive effect on the quality of the cartilage

The histology and mechanics of leg lengthening by callus distraction were studied in 27 growing rabbits. Tibial diaphyses were subjected to subperiosteal osteotomy, held in a neutral position for 10 days and then slowly distracted at 0.25 mm/12 hours, using a dynamic external fixator. Radiographs showed that the gap became filled with callus having three distinct zones. Elongation appeared to occur in a central radiolucent zone; this was bounded by two sclerotic zones. Histologically, the radiolucent zone consisted of longitudinally arranged cartilage and fibrous tissue while the sclerotic zones were formed by fine cancellous bone. New bone occasionally contained islands of cartilage, suggesting it had been formed by endochondral ossification. After completion of distraction, the two sclerotic zones fused, shrank and were eventually absorbed, leaving tubular bone with a new cortex. When the periosteum had been removed at the operation, callus formation was markedly disturbed and there was failure of bone lengthening. Scraping of endosteum, in contrast, did not have a pronounced effect. These results suggest that the preservation of periosteum is essential if bone lengthening by callus distraction is to succeed, and that preservation of the periosteum is more important than careful corticotomy

We subjected the proximal tibial growth plates of six-week-old rabbits to either compression or distraction of 1 kg on both legs. On one side the proximal tibial periosteum was divided circumferentially and stripped for 1 cm. After six weeks, growth was measured at both proximal and distal growth plates. Compression inhibited total tibial growth and distraction enhanced it. The compressed growth plate grew less and the distracted growth plate grew more, but there was a reciprocal change at the other end of the bone. Periosteal division enhanced growth at the adjacent growth plate but inhibited it distally; the effect of distraction was enhanced and that of compression reduced. We found reciprocal growth rates at the proximal and distal growth plates. Relatively small amounts of compression or distraction did affect total bone growth. Periosteal division appeared to induce overgrowth at least partly by a mechanical effect; it may be useful as an adjunct to other methods of leg lengthening, though not to epiphyseolysis

We present a series of ten hypertrophic nonunions in which bony alignment and length were restored and union induced by external fixation and callus distraction. The mean length gained was 3.5 cm (1 to 6) and the mean angular correction was 13.5° (0 to 40). The mean treatment time was 10.2 months (3 to 15) and mean follow-up was 40 months (6 to 71). There have been no refractures or loss of correction or length. The technique of callus distraction at a site of hypertrophic nonunion can correct shortening and angulation as well as induce bony union. No extra equipment is needed beyond readily-available external fixation systems

Between 1986 and 1994, 13 patients with mobile painful arthritic elbows were treated by distraction interposition arthroplasty using fascia lata. The mean period of follow-up was 63 months. An elbow distractor/fixator was applied for three to four weeks to separate the articular surfaces and to protect the fascial graft. Nine of the 13 patients (69%) had satisfactory relief from pain; eight (62%) had an excellent or good result by the objective criteria of the Mayo Elbow Performance score. Four have required revision to total elbow arthroplasty at a mean of 30 months with good results to date. Instability of the elbow, both before and after surgery, was found to be associated with unsatisfactory results. The rate of success when the procedure was performed for inflammatory arthritis was similar to that for post-traumatic arthritis, about 67%. Eight complications occurred in six patients, all in the group with post-traumatic arthritis. Two of these required further surgical procedures such as transposition of the ulnar nerve or repair of hernia of the fascia lata. Although less reliable than prosthetic replacement, distraction interposition arthroplasty is a useful option in the treatment of young, high-demand patients with arthritis of the elbow. It is rarely indicated in the presence of generalised inflammatory arthritis, but may be of value in those patients in whom the disease is limited primarily to the elbow

Ten epiphyses in seven children underwent fixed-rate distraction of 0.25 mm twice daily in an attempt to achieve percutaneous leg lengthening by chondrodiatasis. The forces generated across the growth plate were recorded by means of strain gauges incorporated into the distractors. All epiphyses fractured before 33 days of lengthening. An average gain of 6.75 cm was achieved. Epiphyseal distraction at the lower femur produced many complications, but at the upper tibial epiphysis planned lengthening was achieved, with excellent bone production and few complications

We developed a rat model of limb lengthening to study the basic mechanism of distraction osteogenesis, using a small monolateral external fixator. In 11-week-old male rats we performed a subperiosteal osteotomy in the midshaft of the femur with distraction at 0.25 mm every 12 hours from seven days after operation. Radiological and histological examinations showed a growth zone of constant thickness in the middle of the lengthened segment, with formation of new bone at its proximal and distal ends. Osteogenic cells were arranged longitudinally along the tension vector showing the origin and the fate of individual cells in a single section. Typical endochondral bone formation was prominent in the early stage of distraction, but intramembraneous bone formation became the predominant mechanism of ossification at later stages. We also showed a third mechanism of ossification, ‘transchondroid bone formation’. Chondroid bone, a tissue intermediate between bone and cartilage, was formed directly by chondrocyte-like cells, with transition from fibrous tissue to bone occurring gradually and consecutively without capillary invasion. In situ hybridisation using digoxigenin-11-UTP-labelled complementary RNAs showed that the chondroid bone cells temporarily expressed type-II collagen mRNA. They did not show the classical morphological characteristics of chondrocytes, but were assumed to be young chondrocytes undergoing further differentiation into bone-forming cells. We found at least three different modes of ossification during bone lengthening by distraction osteogenesis. We believe that this is the first report of such a rat model, and have shown the validity of in situ hybridisation techniques for the study of the cellular and molecular mechanisms involved in distraction osteogenesis

We present a retrospective study of 27 patients treated by callus distraction using a unilateral external fixator of our own design for nonunion with bone loss and shortening of the femur caused by suppurative osteomyelitis. The unilateral external fixator was used either alone or in combination with an intramedullary nail. The mean age of the patients was 13.6 years (8 to 18). The fixator was used alone in 13 patients and with an intramedullary nail in 14. The bone results at a mean follow-up of 88 months (37 to 144) were excellent in 16 patients and good in 11. The functional results were excellent in 18 patients and good in nine. However, four patients still had draining sinuses at the latest follow-up. A residual deformity greater than 7° was present in seven femora, but this did not adversely affect function or require further treatment

Limb lengthening by callus distraction and external fixation has a high rate of complications. We describe our experience using an intramedullary nail (Fitbone) which contains a motorised and programmable sliding mechanism for limb lengthening and bone transport. Between 2001 and 2004 we lengthened 13 femora and 11 tibiae in ten patients (seven men and three women) with a mean age of 32 years (21 to 47) using this nail. The indications for operation were short stature in six patients and developmental or acquired disorders in the rest. The mean lengthening achieved was 40 mm (27 to 60). The mean length of stay in hospital was seven days (5 to 9). The mean healing index was 35 days/cm (18.8 to 70.9). There were no cases of implant-related infection or malunion

The clinical results of 26 digits (18 patients) lengthened by distraction callotasis were evaluated and the factors which influenced healing were analysed. There were 14 men and four women, with a mean age of 39 years. All digits had suffered traumatic amputation. There were eight thumbs and 18 fingers. The level of the site of the osteotomy was at the proximal metaphysis in ten, the middle diaphysis in 13 and the distal metaphysis in three. Although the proposed length was achieved in 23 of the 26 digits, five required additional bone grafts. The rate of healing was 96 days/cm in the digits without complications such as callus fracture or poor callus formation, and 158 days/cm in those with complications. Lengthening at the proximal metaphysis gave a better result than at the diaphysis or distal metaphysis

Limb lengthening by means of distraction through the callus of a knee arthrodesis was performed in a 14-year-old boy with congenital hypoplasia of one lower limb. Knee arthrodesis was indicated because of destruction of the distal femoral epiphysis caused by a previous bone lengthening procedure

We lengthened seven first metatarsals in four patients with short great toes by callus distraction using an external fixator. Good clinical and cosmetic results were obtained. Bone lengthening is effective in patients with short great toes not only for cosmesis, but also to relieve pain and callosities on the plantar aspect of the second and third metatarsal heads. Excessive lengthening of the first metatarsal resulted in limitation of the range of movement of the metatarsophalangeal joint of the great toe. To prevent this the amount of lengthening should not exceed 40% of the preoperative length of the metatarsal

We report the results of distraction osteogenesis (callotasis) for the reconstruction of extensive defects after the excision of skeletal tumours in the limbs. Bone transport was performed in ten patients (five osteosarcomas and five giant-cell tumours), shortening-distraction in three (two osteosarcomas and one Ewing’s sarcoma), and distraction osteogenesis combined with an intramedullary nail to reduce the time of external fixation in six (three osteosarcomas, two chondro-sarcomas, and one malignant fibrous histiocytoma). The mean length of the defects after excision of the lesion was 8.4 cm. The mean external fixation index was 39.5 days/cm for the group treated by bone transport, 34.1 days/cm for the shortening-distraction group, and 24.0 days/cm for the group treated by distraction and an intramedullary nail. Functional evaluation gave excellent results in 12 patients, good in five and fair in two. There were ten complications in 19 patients, all of which were successfully treated. We also classified reconstruction using distraction osteogenesis into five types based on the location of the defects after resection of the tumour: type 1, diaphyseal; type 2, metaphyseal; type 3, epiphyseal; type 4, subarticular reconstruction; and type 5, arthrodesis. Our results suggest that reconstruction using distraction osteogenesis provides bone which will develop sufficient biomechanical strength and durability. It is beneficial in patients with an expectation of long-term survival and in growing children

This retrospective study analyses the results of subtalar bone block distraction arthrodesis used in the treatment of late complications of calcaneal fractures, acute severely comminuted fractures, nonunion (and malunion) of attempted subtalar arthrodeses, avascular necrosis of the talus, and club-foot deformity. Of 39 patients (41 feet) who had this procedure, 35 (37 feet) returned for follow-up after a mean of 70 months (26 to 140). There were 24 men (25 feet) and 11 women (12 feet) with a mean age of 41 years (16 to 63). Each completed a standardised questionnaire, based on the hindfoot-scoring system of the American Orthopaedic Foot and Ankle Society and were reviewed both clinically and radiologically. Of the 37 operations, 32 (87%) achieved union. The mean hindfoot score (maximum of 94 points) increased from 21.1 points (8 to 46) preoperatively to 68.9 (14 to 82) at the final follow-up. The mean talocalcaneal and calcaneal pitch angles were 20.5° and 4.9° before operation, 25.9° and 8.3° immediately after, and 24.6° and 7.7° at the final follow-up, respectively. The mean talar declination angle improved from 6.5° (−10 to 22) before operation to 24.8° (14 to 32) at the final follow-up. The mean talocalcaneal height increased from 68.7 mm before operation to 74.5 mm immediately after and 73.5 mm at the final follow-up. Of the 37 arthrodeses available for review, 32 were successful; 29 patients (30 arthrodeses) were satisfied with the procedure. Minimal loss of hindfoot alignment occurred when comparing radiographs taken immediately after operation and at final follow-up

We describe the technique and results of medial submuscular plating of the femur in paediatric patients and discuss its indications and limitations. Specifically, the technique is used as part of a plate-after-lengthening strategy, where the period of external fixation is reduced and the plate introduced by avoiding direct contact with the lateral entry wounds of the external fixator pins. The technique emphasises that vastus medialis is interposed between the plate and the vascular structures.

A total of 16 patients (11 male and five female, mean age 9.6 years (5 to 17)), had medial submuscular plating of the femur. All underwent distraction osteogenesis of the femur with a mean lengthening of 4.99 cm (3.2 to 12) prior to plating. All patients achieved consolidation of the regenerate without deformity. The mean follow-up was 10.5 months (7 to 15) after plating for those with plates still in situ, and 16.3 months (1 to 39) for those who subsequently had their plates removed. None developed a deep infection. In two patients a proximal screw fractured without loss of alignment; one patient sustained a traumatic fracture six months after removal of the plate.

Placing the plate on the medial side is advantageous when the external fixator is present on the lateral side, and is biomechanically optimal in the presence of a femoral defect. We conclude that medial femoral submuscular plating is a useful technique for specific indications and can be performed safely with a prior understanding of the regional anatomy.

Cite this article: Bone Joint J 2014;96-B:137–42.

We have treated 12 adolescent patients with idiopathic tibia vara by asymmetrical physeal distraction using a modified Wagner external fixator. There were no major complications and a mean correction of 13 degrees was achieved. The main advantages of the technique are that no osteotomy, internal fixation or bone graft is needed, and that the operation can be performed on both tibiae simultaneously. No shortening is produced and lengthening can be added to angular correction if required

Subtalar distraction bone-block arthrodesis for malunited calcaneal fractures was performed in 31 patients (26 men, five women), with a mean age of 38.5 years. The mean time from injury to arthrodesis was 36 months. There were no cases of nonunion. One patient had an early dislocation of the bone block requiring a repeat arthrodesis, and one had a soft-tissue infection. The mean AOFAS hindfoot score improved significantly from 23.5 before operation to 73.2 at a mean follow-up of 33 months (p > 0.001). Compared with the unaffected side, the talocalcaneal height was corrected by 61.8%, the talus-first metatarsal axis by 46.5%, the talar declination angle by 38.5% and the talocalcaneal angle by 35.4%. Dynamic pedobarography revealed a return to normal of the pressure distribution during roll-over and a more energetic gait. The distribution of local transfer of load correlated well with the AOFAS score. The amount of correction of the heel height correlated with a normal pattern of pressure transfer on the heel (p < 0.05)