Tibial nonunion represents a spectrum of conditions which are challenging to treat, and optimal management remains unclear despite its high rate of incidence. We present 44 consecutive patients with 46 stiff tibial nonunions, treated with hexapod external fixators and distraction to achieve union and gradual deformity correction. There were 31 men and 13 women with a mean age of 35 years (18 to 68) and a mean follow-up of 12 months (6 to 40). No tibial osteotomies or bone graft procedures were performed. Bony union was achieved after the initial surgery in 41 (89.1%) tibias. Four persistent nonunions united after repeat treatment with closed hexapod distraction, resulting in bony union in 45 (97.8%) patients. The mean time to union was 23 weeks (11 to 49). Leg-length was restored to within 1 cm of the contralateral side in all tibias. Mechanical alignment was restored to within 5° of normal in 42 (91.3%) tibias. Closed distraction of stiff tibial nonunions can predictably lead to union without further surgery or bone graft. In addition to generating the required distraction to achieve union, hexapod circular external fixators can accurately correct concurrent deformities and limb-length discrepancies. Cite this article: Bone Joint J 2015;97-B:1417–22

Introduction. Segmental bone defect is a challenging problem. We report our experience of bone transport by hexapod external fixator in patients with segmental defects if the tibia. Method. We report herein 15 patients with segmental bone defect of tibia who completed their treatment protocol. All patients were treated had bone transport with Taylor Spatial Frame from 2012 to 2017. All were treated by the senior author NH. Parameters measured included age, sex, diabetes, smoking, diagnosis, method of fixation prior to treatment use of a free flap, bone defect size, frame-time, external fixation index. Results. Mean age at the time of frame application was 42.7 years. Mean follow-up after frame removal was 23.7 months. Three were diabetic, one smoked and one quit smoking during treatment. Seven had Gustilo-Anderson 3B (47%) and 5 Gustilo-Anderson 3A (33%) open fractures. Three (20%) had closed fractures. Nine (60%) had internal fixation with plate in eight and IM nail in one. Ten patients (67%) had soft tissue defect that required a free flap in seven, local flap in two and skin graft in one. Mean transport was 62 mm. Mean external fixator time and latency were 350.1 and 12 days, respectively. Mean External fixator, distraction and maturation indices were 2.1, 0.52 and 1.43 month per centimeter, respectively. Ten Extra- procedures were required in 7 patients. There were no docking site procedures, non-union of regenerate, adjunctive stabilization after frame removal, recurrence of bone infection and recurrence of deformity. Conclusions. Segmental resection and transport by TSF is an effective method to achieve length, alignment and eradicate infection. Although our cohort had longer external fixator indices than similar studies, the complication rate was low

Aim. To investigate the biomechanical behaviours of the TL-Hex & Taylor Spatial Frame (TSF) Hexapod external fixators, with comparison to traditional ring-fixator constructs. Methods. Standardised four-ring TL-Hex and TSF constructs, as well as matched ilizarov threaded-rod constructs for each set of components, were tested alone and mounted with an acrylic bone model with simulated fracture gap using fine-wires. Load-deformation properties for each construct and mode of loading were calculated and analysed statistically using ANOVA. Results and Conclusions. Under axial loading the Ilizarov construct utilising TL-Hex components demonstrated greatest rigidity followed by the TL-Hex Ilizarov using TSF components (p<0.01). Under torsional loading both hexapod frames were seen to be significantly more rigid than the Ilizarov (p<0.01), with the TSF demonstrating greater rigidity than the TL-Hex. Under cantilever bending loads the difference in rigidity seen across all constructs was less marked. When loaded with the bone model both hexapods demonstrated reduced axial rigidity as compared to Ilizarov constructs, but without any appreciable difference in translational shear strain. Under cantilever bending the Ilizarov construct using TL-Hex components p<0.01) demonstrated less translational shear strain than the TSF and TSF using Ilizarov components. In conclusion, both hexapod designs were less rigid axially, but more so under bending and torsional loads, than their Ilizarov construct counterparts, producing greater overall planar shear strain, largely due to the observed “toe-in” laxity. Overall, the TL-Hex was seen to be more rigid that the TSF under bending loads although the difference in shear strain at the fracture site was not significantly different

Aim. To quantify the micro-motion at the fracture gap in a tibial fracture model stabilised with an external fixator. Method. A surrogate model of a tibia and a cadaver leg were fractured and stabilised using a two-ring hexapod external fixator. They were tested initially under static loading and then subjected to vibration. Results. The overall stiffness of the cadaver leg was significantly higher than the surrogate model under static loading. This resulted in a significantly higher facture movement in the surrogate model. In the surrogate model there was no significant difference between the displacement applied via the vibrating platform and the fracture movement at the fracture gap. The fracture movement was however found to be statistically lower during vibration in the cadaver leg. Discussion. The significant difference in stiffness seen between the surrogate and cadaveric model is likely due to multiple factors such as the presence of soft tissues and fibula, including the biomechanical differences between the frame constructs. The fracture movement seen at 200N loading in the cadaveric leg was approximately 1mm which corresponds to partial weight bearing and a displacement shown to promote callus formation. During vibration however, the movements were far less suggesting that micromotion would be insufficient to promote healing. It may be proposed that soft tissues can alter the overall stiffness and fracture movement recorded in biomechanical studies investigating the effect of various devices or therapies

Purpose. To review the natural history of posteromedial bowing of the tibia and the outcome of limb reconstruction in this condition. Patients and Methods. 38 patients with posteromedial bowing of the tibia presenting between 2000–2016 were identified. Mean follow up from presentation was 78 months. Seventeen patients underwent lengthening and deformity correction surgery, whilst 3 further patients are awaiting lengthening and deformity correction procedures. Results. The greatest correction of deformity occurred in the first year of life, but after the age of 4 years, remodelling was limited. The absolute leg length discrepancy (LLD) increased throughout growth with a mean 14.3% discrepancy in tibial length. In the lengthening group, mean length gained per episode was 45mm (35–60). Mean duration in frame was 192 days, with a healing index of 42.4 days/cm. Significantly higher rates of recurrence in LLD were seen in those undergoing lengthening under the age of 10 years (p=0.046). Four contralateral epiphysiodeses were also performed. Conclusions. Posteromedial bowing of the tibia improves spontaneously during the first years of life, but in 20/38 (53%) patients, limb reconstruction was indicated for significant residual deformity and/or worsening length discrepancy. For larger discrepancies and persistent deformity, limb reconstruction with a hexapod external fixator is an effective technique and should be considered as part of the treatment options. Level of evidence. Level 4 (Case series)

Introduction. Fracture and deformity after frame removal is a known risk in 9–14.5% of patients after circular frame treatment. The aims of this study were to assess the effectiveness of our staged protocol for frame removal and risk factors for the protocol failure. Methods and materials. We identified 299 consecutive patients who underwent circular frame fixation for fracture or deformity correction in our unit from our prospective database. All 247 patients who followed the staged frame removal protocol were included in this study. We reviewed the electronic clinical record and radiographs of each patient to record demographics, risk factors for treatment failure and outcome following frame removal. We defined failure of the protocol as a re-fracture or change in bony alignment within 12 weeks of frame removal. Results underwent statistical analysis using Chi square analysis. Results. Of the 247 patients, 196 were trauma patients, of which 56 were open fractures and 48 were elective cases. There were 92 Ilizarov frames and 155 hexapods. 93 patients were smokers. The protocol failed to prevent mechanical failure after frame removal in 10 patients, of which four had refracture and six had an increase in deformity. The average increase in deformity was 7.7 in the frontal plane and 3.8 in the lateral plane. We identified risk factors for mechanical failure in eight of the ten; four were smokers, two were on steroids and two had hypophosphataemic rickets. Of the ten patients, four were for elective indications, six for trauma. Two of the six trauma patients had been treated for open fractures. ‘The type of frame and smoking history showed no statistical association with mechanical failure. Four patients went to have another frame, five were managed with plaster and one patient refused further treatment. Conclusion. Our staged reloading protocol may delay frame removal however it is a simple and effective way to confirm the timing of frame removal

Background:. Lower limb reconstruction is performed in trauma centres where uplifted tariffs support the treatment of severely injured patients. Calculation of Healthcare Resource Groups (HRG4) codes is affected by the accuracy of clinical coding, determining the financial viability of this service in a district general hospital (DGH). Methods:. A prospective review of coding was performed for 17 sequential patients treated using ring fixation. Relevant clinical codes and HRG4 tariffs were obtained, allowing comparison with operation notes (including pertinent diagnostic information) and implant costs. Hexapod and paediatric cases were excluded. Results:. Mean implant costs were £3,300 and mean tariffs were £9,300. However, the tariffs for the care episodes which did not attract a code for ‘reconstruction’ were lower, averaging £4,300. Clinical outcomes were comparable to published literature. No uplift was received. Discussion:. Despite attempts to avoid mis-coding for the fledgling service and factoring ancillary costs of patient care, the ring fixation procedures which resulted in HRG4 codes other than those for limb reconstruction cost the trust more than it received. Conclusion:. Lower limb reconstruction is barely financially viable even when coding is carefully performed. It is financially easier for this Trust to transfer patients to a trauma centre

Background:. Little is known about the forces carried by the Taylor Spatial Frame (TSF) hexapod fixator. Our aim was to measure the TSF resultant force and how this changed during the consolidation phase. Method:. Five patients undergoing correction of tibial deformities were recruited. Measurements were taken at 2, 4, 8 and 12 weeks post-correction during various activities. Instrumented struts incorporating strain gauges measuring axial force were temporarily used each time. Strut forces and lengths were used to determine frame kinetics. The resultant axial fixator forces and moments were calculated relative to sitting. Ground reaction forces (GRF) were measured using the treadmill force plates. Results & Discussion:. Due to the subjects' varying confidence in weight bearing the forces varied both inter- and intra-activity and over post-corrective time. Variation in individual strut forces produced a resultant force and bending moment across the fixation. As the healing bone assumed more load over time there was a reduction in the force and bending excursions across the frame as a percentage of GRF, achieving a minimum by 8 weeks. Conclusion:. Instrumented TSFs are a useful means of assessing the forces acting during healing. Monitoring of these forces can determine optimal removal

Introduction. Fracture healing is governed by biological and mechanical factors. Circular frames are one method to fix fractures. Recently, the number of frame designs that are available has increased and these different designs may have different effects on the mechanical environment created. The senior author has been concerned by the stability of the construction when a short frame is used. This study examined the stability of different frames and the possible use of additional 7th struts to aid stability. Method. The frame configuration was modified with increasing strut angles from 15° − 70°. Each frame was cyclically tested in compression to 200N. The Taylor Spatial Frame was retested with the addition of a seventh strut. Results. Frame stability significantly deteriorated with shorter struts. This was particularly apparent at angles less than 30°. Stiffness was significantly improved with the addition of a seventh strut. Conclusions. Ring-strut angle, plays a significant factor in hexapod frame stability. Stability can be improved with the addition of a seventh strut. This may be particularly important in the paediatric community and in frame around the thigh were a larger ring may increase the strut angle