Study points to effectiveness of using circular hexapod devices
The use of circular hexapod devices was found to provide a safe, minimally invasive surgical alternative method to open reduction and internal fixation (ORIF) in patients with severe open tibial fractures, achieving high bony union rates and excellent limb salvage results, according to research presented in a scientific poster at the 2016 AAOS Annual Meeting.
The study, led by Dr. Satyajit Naique, FRCS(Orth), MS, of Imperial College Healthcare National Health Service Trust in London, involved 255 patients with open tibial fractures who were treated at a level I trauma center over 3 years. Of these, 55 consecutive patients (55 fractures; 45 male, 10 female) treated with a circular frame were retrospectively enrolled. All fractures were deemed high risk for internal fixation. Gustilo-Anderson classification was grade 3C in 1 patient, grade 3B in 42 patients, grade 3A in 7 patients, and grade 2 in 5 patients. Inclusion criteria included definitive fixation with a hexapod frame, Gustilo-Anderson grade 2 or greater open tibial fracture, skeletal maturity, and follow-up of at least 6 months, after frame removal performed at the center.
All injuries were managed according to the British Orthopaedic Association Standards for Trauma (BOAST) 4 guidelines. Devices used ranged from 2-ring frames to 4-ring double-level correction for more complex segmental fractures. Two different models of hexapods were used. Six grade 3B fractures required acute shortening, and those with 2.5 cm or more of shortening had concurrent limb lengthening. Two fractures had staged bone grafting: one for a 10 cm defect reconstructed using the Masquelet technique and one involving bone transport with docking site bone grafting. The plastic surgery service performed soft-tissue reconstruction using direct closure in 20 patients, local flaps in 20 patients, and free flaps in 15 patients.
"Our main aim was to look at incidence of deep infection and presence of and time to union," principal author Konstantinos J. Doudoulakis, MD, MSc, commented. "Our secondary aim was to look at residual deformity, leg length discrepancy, and complications."
Of the 55 fractures, 50 (91 percent) healed completely at the time of frame removal. In the remaining five patients, the frame was removed either because of patient insistence or because the fracture was judged to have healed clinically. Four of these cases required a below-knee boot, while one patient had further fixation with an intramedullary nail. Average time to frame removal was 32.7 weeks, and average time to union was 32.6 weeks.
Of the patients treated with direct closure, mean union times were 27.5 weeks, with four fractures not uniting. Patients with local flaps all exhibited bony union, with a mean time of 33.9 weeks. All patients but one treated with free flaps experienced union at 230 days. Bone union for 3B fractures occurred with a median of 30.3 weeks; for 3A fractures, median union was at 21.3 weeks, and for GA 2 fractures, it was 25.5 weeks.
Some 41.8 percent of patients had superficial pin site infections, which were treated with oral antibiotics. There were no persistently infected fractures or osteomyelitis. The patient with the 10 cm defect had a refracture requiring a further frame for 3 months to consolidate, and another patient had a fracture site refracture 1 year later that healed in a boot.
Two patients had local fasciocutaneous flap failures (3.6 percent) necessitating free flaps. No delayed amputations were needed.
ASAMI bone scores for bony healing, residual deformity, and leg length discrepancy were excellent in 21 patients, good in 23, fair in 6, and poor in 5 patients, all of whom had nonunion. Alignment was deemed satisfactory in all cases. Other complications were nerve irritation (2 patients), strut extrusion (4), wire breakage (2), and pin removal (2).
"This select group of severe open tibial fractures is composed of injuries that are notoriously difficult to manage due to their high complication rates," Dr. Naique commented. "The conventional techniques of internal fixation do work but are not ideal in severe open fractures with significant soft tissue loss and are associated with high rates of deep infection and failure of limb salvage."
He noted that at his trauma center, work using the combined approach for management of severe open tibial fractures with the use of circular hexapod frames began in the 1990s. Since then, he said, "the experience has grown substantially and our results have improved remarkably, with our recent work published in The Bone & Joint Journal showing a bone infection rate of 1.6 percent.
"While the efficacy of hexapod circular frames has been well documented in the adult reconstruction and deformity correction literature," he continued, "their use in acute trauma is yet to be well established and accepted. This study may serve to set a benchmark for the treatment of these severe injuries."
According to Dr. Naique, the study's findings confirmed the initial hypothesis regarding the efficacy and safety of the use of circular frames, while yielding additional positive results to be investigated further.
"Having seen patients in clinics, we already had a feeling that those with frames were functionally doing well, even better at times—than the ORIF group, although they were a more severely injured cohort," he said. "It was surprising to see that patients adapted very quickly to the frames and reassuring to see them to full weight bearing and to work very early."
He noted that the group also saw a substantial drop in rates of deep infection, "probably due to the minimally invasive nature of the procedure, preservation of bone and soft tissue blood supply, and minimal burden of metal at the site of injury."
In conclusion, he said, "these devices are safe and efficacious in the management of severe injuries. They are versatile in treating concomitant diaphyseal and intra-articular injuries. They are truly minimally invasive and preserve soft tissue, allowing the fractures to heal well and in good alignment. The software helps the surgeon to fine-tune alignment in the office. It also allows concomitant limb lengthening in cases with bone loss."
One drawback to the use of frames, he said, is that their use requires careful pin site care to prevent superficial infection, which, he added, is seen to leave no long-term effects. The use of circular frames also requires "appropriate surgeon training as a team to monitor and guide patients through their treatment."
The study by Dr. Naique and Dr. Doudoulakis was presented in Poster 476, "Management of Severe Open Tibial Fractures Using Circular Hexapod Frames."
Terry Stanton is the senior science writer for AAOS Now. He can be reached at email@example.com
- Conventional methods of internal fixation are effective in open tibial fractures, but the use of circular frames offers more advantages such as stable fixation away from the zone of injury, reduced metal burden and hence perceived infection in bone, and ability to fine tune alignment in an outpatient setting.
- Of the 55 fractures in the study managed with circular frames, 50 had healed completely at time of frame removal.
- Average time to frame removal was 32.7 weeks, and average time to union was 32.6 weeks.
- Although superficial pin site infections are an issue with circular frames, their use may be associated with lower rates of deep-tissue infection.