Computer hexapod-assisted orthopaedic surgery provides a predictable and safe method of femoral deformity correction.
OBJECTIVE
Computer hexapod assisted orthopaedic surgery (CHAOS), is a method to achieve the intra-operative correction of long bone deformities using a hexapod external fixator before definitive internal fixation with minimally invasive stabilisation techniques. The aims of this study were to determine the reliability of this method in a consecutive case series of patients undergoing femoral deformity correction, with a minimum six-month follow-up, to assess the complications and to define the ideal group of patients for whom this treatment is appropriate.


METHODS
The medical records and radiographs of all patients who underwent CHAOS for femoral deformity at our institution between 2005 and 2011 were retrospectively reviewed. Records were available for all 55 consecutive procedures undertaken in 49 patients with a mean age of 35.6 years (10.9 to 75.3) at the time of surgery.


RESULTS
Patients were assessed at a mean interval of 44 months (6 to 90) following surgery. The indications were broad; the most common were vitamin D resistant rickets (n = 10), growth plate arrest (n = 6) and post-traumatic deformity (n = 20). Multi-planar correction was required in 33 cases. A single level osteotomy was performed in 43 cases. Locking plates were used to stabilise the osteotomy in 33 cases and intramedullary nails in the remainder. Complications included two nonunions, one death, one below-knee deep vein thrombosis, one deep infection and one revision procedure due to initial under-correction. There were no neurovascular injuries or incidence of compartment syndrome.


CONCLUSIONS
This is the largest reported series of femoral deformity corrections using the CHAOS technique. This series demonstrates that precise intra-operative realignment is possible with a hexapod external fixator prior to definitive stabilisation with contemporary internal fixation. This combination allows reproducible correction of complex femoral deformity from a wide variety of diagnoses and age range with a low complication rate. Cite this article: Bone Joint J 2017;99-B:283-8.
Alfred Hospital, 55 Commercial Road, Melbourne, Australia.
A
A
Hughes
Royal London Hospital, Whitechapel Road, London, UK.
N
N
Heidari
University Hospitals Bristol NHS Trust, Bristol Royal Infirmary, Upper Maudlin Street, Bristol BS2 8HW, UK.
S
S
Mitchell
University Hospitals Bristol NHS Trust, Bristol Royal Infirmary, Upper Maudlin Street, Bristol BS2 8HW, UK.
J
J
Livingstone
University Hospitals Bristol NHS Trust, Bristol Royal Infirmary, Upper Maudlin Street, Bristol BS2 8HW, UK.
M
M
Jackson
University Hospitals Bristol NHS Trust, Bristol Royal Infirmary, Upper Maudlin Street, Bristol BS2 8HW, UK.
R
R
Atkins
University Hospitals Bristol NHS Trust, Bristol Royal Hospital for Children, Upper Maudlin Street, Bristol, UK.
F
F
Monsell
D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D016267:External Fixators; D005260:Female; D005269:Femur / Q000002:abnormalities / Q000000981:diagnostic imaging / Q000293:injuries / Q000601:surgery*; D005593:Fracture Fixation, Internal; D006801:Humans; D007869:Leg Injuries / Q000175:diagnosis / Q000601:surgery*; D038061:Lower Extremity Deformities, Congenital / Q000000981:diagnostic imaging / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D019060:Minimally Invasive Surgical Procedures; D010027:Osteotomy; D015203:Reproducibility of Results; D012189:Retrospective Studies; D025321:Surgery, Computer-Assisted / Q000295:instrumentation; D055815:Young Adult
Acute correction; Deformity; Femoral deformity; Taylor spatial frame