The computer-aided parallel external fixator for complex lower limb deformity correction

Management of Elderly Traumatic Ankle Arthritis with Ilizarov External Fixation

Objective

To evaluate the clinical curative effect of Ilizarov external fixation and ankle arthrodesis in the treatment of elderly traumatic ankle arthritis.

Methods

From June 2013 to August 2019, 72 patients with elderly traumatic ankle arthritis were treated with arthrodesis through Ilizarov external fixation technique in our institution. Conventional double‐feet standing X‐ray films were taken before and after operation. The tibiotalar angle on X‐ray image was measured to evaluate the degree of talipes varus and valgus. The Foot and Ankle pain score of American Orthopaedics Foot and Ankle Society (AOFAS) and Visual Analog Scale (VAS) were compared by using paired t‐test to evaluate the functional recovery.

Results

All of the patients acquired effective postoperative 18–49 months follow‐up, with an average of 31.5 months. All patients were included in the analysis, among which 38 cases were males and 34 cases were females, with an average of 65.4 years (ranging from 60 to 74). All ankles achieved bony fusion; the clinical healing time was 12.7 weeks on average (11–18 weeks). The AOFAS score was 45.36 ± 6.43 preoperatively and 80.25 ± 9.16 at 12 months post‐operation, with a statistically significant difference (p < 0.0001). The VAS score was 8.56 ± 1.85 on average preoperatively and 2.72 ± 0.83 at 12 months post‐operation, with a statistically significant difference (p < 0.0001). The tibiotalar angle was 101.93° ± 4.12° preoperatively and 94.45° ± 2.37° at 12 months post‐operation, with a statistically significant difference (p < 0.0001). The results of the functional evaluation indicated that 44 patients (61.1%) had excellent results, 18 (25%) had good results, and 10 (13.9%) had fair results.

Conclusion

Our study demonstrated that it is possible to obtain satisfactory outcome with Ilizarov external fixation and ankle arthrodesis in the treatment of elderly traumatic ankle arthritis.

Retrospective clinical outcomes in the definitive treatment of high-energy tibial diaphyseal fractures using hexapod external fixator versus monolateral external fixator

BACKGROUND

External fixation, which can preserve the biomechanical microenvironment of fracture healing, plays an important role in managing the high-energy fractures with poor surrounding soft tissues. The purpose of this study was to determine the differences of clinical outcomes, if any, between hexapod external fixator and monolateral external fixator in the definitive treatment of high-energy tibial diaphyseal fractures.

METHODS

A total of 53 patients with high-energy tibial diaphyseal fractures and definitively treated by the hexapod external fixator (HEF) or monolateral external fixator (MEF) were retrospectively collected and analyzed, from March 2015 to June 2019. There were 31 patients in the HEF treatment, and the other 22 patients were managed by the MEF. The demographic data, surgical duration, external fixation time, final radiological results, complications, and clinical outcomes were documented and analyzed. Difficulties that occurred during the treatment were classified according to Paley. The clinical outcomes were evaluated by the Association for the Study and Application of the Method of Ilizarov criteria (ASAMI) at the last clinical visit.

RESULTS

The mean surgical duration in the HEF group (62.4 ± 8.3 min) was shorter than that in the MEF group (91.4 ± 6.9 min) (P < 0.05). All patients acquired complete bone union finally. Patients in the HEF group (24.2 ± 3.1 weeks) underwent a shorter average external fixation time than that in the MEF group (26.3 ± 3.8 weeks) (P < 0.05). Satisfactory alignment was achieved in all patients without the need for remanipulation. The residual sagittal plane deformities in the HEF group were all less than that in the MEF group (P < 0.05). The complication rate was 35.5% in the HEF group, while 45.5% in the MEF group. There was no statistically significant difference between the two groups in ASAMI scores (P > 0.05).

CONCLUSION

There is no statistically significant difference in finally clinical outcomes between hexapod external fixator and monolateral external fixator in the definitive treatment of high-energy tibial diaphyseal fractures. The hexapod external fixation treatment is a superior effective method, including advantages of stable fixation, less surgical duration, postoperatively satisfactory fracture reduction, and fewer complications.

Correction outcomes of the postoperative malalignment salvaged by the temporary application of the hexapod external fixator in tibial diaphyseal fractures treated by monolateral external fixation

BACKGROUND

Postoperative malalignment in fractures treated by monolateral external fixation is not uncommon in clinical practice. Accurate reduction without excessive tissue disruption caused by surgical intervention and sequentially manage the fractures using monolateral external fixation for definitive treatment is still a challenge for surgeons. The purpose of our study was to evaluate the feasibility and effectiveness of the temporary application of the hexapod external fixator (HEF) for the postoperative malalignment correction in tibial diaphyseal fractures treated by monolateral external fixation.

METHODS

We carried out a retrospective analysis of 23 trauma patients with tibial diaphyseal fracture treated by the monolateral external fixation at our institution from January 2016 to May 2019. There were 21 males and 2 females with a mean age of 38 years (range 18-60 years). The hexapod external fixator was temporarily applied due to postoperative malalignment within two weeks and who unwilling to undergo a secondary surgical intervention. For patients with postoperative malalignment requiring correction, the HEF components were installed on the original existing half pins of the monolateral external fixator after removing the connecting rod. The standard anteroposterior and lateral X-rays of the injured limb combined with the temporary HEF were conducted to measure the hexapod external fixator parameters. Any residual deformities were corrected by gradual struts adjustment with the aid of computer-based software. When satisfactory alignment was achieved, the HEF was removed, and the monolateral external fixator was sequentially used as the definitive structure.

RESULTS

All patients acquired functional reduction, which was evaluated by radiographs. The mean correction time was 4 days (range 2 to 8 days). The mean coronal plane translation (1.3±1.0 mm), coronal plane angulation (0.9±0.7°), sagittal plane translation (1.4±1.1 mm), and sagittal plane angulation (0.7±0.7°) after correction were all less than those (7.0±4.9 mm, 4.7±2.3°, 5.6±3.6 mm, 3.2±2.5°) before correction.

CONCLUSIONS

The temporary application of the hexapod external fixator is an alternative and feasible method for the postoperative malalignment correction in tibial diaphyseal fractures treated by monolateral external fixation.

Intraoperative acute correction versus postoperative gradual correction for tibial shaft fractures with multiplanar posttraumatic deformities using the hexapod external fixator

BACKGROUND

The purpose of this study was to determine the differences in clinical outcomes, if any, between intraoperative acute correction and postoperative gradual correction for tibial shaft fractures with multiplanar posttraumatic deformities using the hexapod external fixator.

METHODS

We retrospectively analyzed 58 consecutive patients with tibial shaft fractures treated by the hexapod external fixator at our institution from January 2015 to April 2019. Twenty-three patients (Group I) underwent intraoperative acute correction, from January 2015 to October 2016. Starting in November 2016, the other 35 patients (Group II) all underwent postoperative gradual correction. The demographic data, operation duration, original residual deformities before correction, residual deformities after correction, and external fixation time were collected and analyzed. The clinical outcomes were evaluated by the Johner-Wruhs criteria at the last clinical visit.

RESULTS

All patients achieved complete bone union with a mean time of 28.7 ± 4.6 weeks (range 21 to 37 weeks) in Group I and 27.9 ± 4.8 weeks (range 19 to 38 weeks) in Group II (P > 0.05). The operation duration in Group I (88.9 ± 7.7 min) was longer than that in Group II (61.9 ± 8.4 min), and there was a statistically significant difference (P < 0.05). There were no statistically significant differences between the two groups in original residual deformities before correction and residual deformities after correction (P > 0.05). The rate of postoperative complication was similar between the two groups. There was no statistical significance in demographic data and clinical outcomes between the two groups (P > 0.05).

CONCLUSIONS

There is no difference in clinical outcomes between intraoperative acute correction and postoperative gradual correction for tibial shaft fractures with multiplanar posttraumatic deformities using the hexapod external fixator. Postoperative gradual correction may shorten the duration in the operation room and decrease the potential intraoperative risk.

Influence of parameter deviation on the closeness of the tibial limb and external fixator based on a novel collision detection algorithm

The Ortho-SUV frame (OSF) is a hexapod external fixator widely applied in orthopedics deformity correction. The possibility of collision between OSF's struts and the soft tissue is an essential but overlooked issue. To avoid the issue, a novel collision detection algorithm is established based on a cone-cylinder model of the tibial limb-strut interaction for detecting the closeness of the tibial limb and external fixator. The algorithm is constructed using the vector analysis based on the model of the minimum distance between the truncated cone generatrix and the cylinder axis. The motion simulation is performed on the overall alignment through the Solidworks-motion module to verify the feasibility of the algorithm. Subsequently, the installation parameter deviations of the bone-fixator system are described to investigate the influence of orientation and position deviation on the closeness of the tibial limb and external fixator through the numerical method. The investigation results show that the orientation deviation γ (around the z-axis), the position deviation τ₁ and τ₂ (along the x and y-axes, respectively) have greater sensitivity to closeness and the influence of multiple deviations on the closeness has the property of superposition. The proposed algorithm can assist clinicians to strictly design and appraise frame configurations prior to their application to avoid the collision between the external fixator and the limbs during the correction. It has great application significance in the development of computer-aided correction software.

Long bone fracture reduction and deformity correction using the hexapod external fixator with a new method: a feasible study and preliminary results

Background

The hexapod external fixator (HEF), such as the Taylor spatial frame (TSF), offering the ability of multidirectional deformities correction without changing the structure, whereas there are so many parameters for surgeons to measure and subjective errors will occur inevitably. The purpose of this study was to evaluate the effectiveness of a new method based on computer-assisted three-dimensional (3D) reconstruction and hexapod external fixator for long bone fracture reduction and deformity correction without calculating the parameters needed by the traditional usage.

Methods

This retrospective study consists of 25 patients with high-energy tibial diaphyseal fractures treated by the HEF at our institution from January 2016 to June 2018, including 22 males and 3 females with a mean age of 42 years (range 14–63 years). Hexapod external fixator treatments were conducted to manage the multiplanar posttraumatic deformities with/without poor soft-tissue that were not suitable for internal fixation. Computer-assisted 3D reconstruction and trajectory planning of the reduction by Mimics were applied to perform virtual fracture reduction and deformity correction. The electronic prescription derived from the length changes of the six struts were calculated by SolidWorks. Fracture reduction was conducted by adjusting the lengths of the six struts according to the electronic prescription. Effectiveness was evaluated by the standard anteroposterior (AP) and lateral X-rays after reduction.

Results

All patients acquired excellent functional reduction and achieved bone union in our study. After correction, the mean translation (1.0 ± 1.1 mm) and angulation (0.8 ± 1.2°) on the coronal plane, mean translation (0.8 ± 1.0 mm) and angulation (0.3 ± 0.8°) on the sagittal plane were all less than those (6.1 ± 4.9 mm, 5.2 ± 3.2°, 4.2 ± 3.5 mm, 4.0 ± 2.5°) before correction (P < 0.05).

Conclusions

The computer-assisted three-dimensional reconstruction and hexapod external fixator-based method allows surgeons to conduct long bone fracture reduction and deformity correction without calculating the parameters needed by the traditional usage. This method is suggested to apply in those unusually complex cases with extensive soft tissue damage and where internal fixation is impossible or inadvisable.

Management of high-energy tibial shaft fractures using the hexapod circular external fixator

Background

The hexapod external fixator (HEF) is increasingly used for high-energy tibial shaft fracture care as more general orthopedic surgeons are gaining expertise of this versatile device. The purpose of this study was to evaluate the clinical effectiveness of the HEF for definitive management in patients with high-energy tibial shaft fractures.

Methods

The study was conducted on 34 patients with tibial shaft fractures who were admitted or referred to our institution and consented to HEF treatment from Jan 2016 to June 2019, including 27 males and 7 females with a mean age of 39 years (range 18 to 65 years). Patients' clinical and radiological data, and the final clinical outcomes at a minimum of 12 months follow-up were collected and retrospectively analyzed. All complications were documented according to Paley’s classification. The clinical outcomes were evaluated using the Association for the Study and Application of the Method of Ilizarov criteria (ASAMI) at the last clinical visit.

Results

All patients remained in the HEF for a mean of 26 weeks (range 15 to 52 weeks) and acquired complete bone union. The satisfactory alignment was achieved in all patients, and all the patients were able to perform daily activities with no difficulty at the last clinical visit. Complications included pin tract infection (44%), delayed union (6%), nonunion (3%), and joint stiffness (3%). The ASAMI bony result was excellent in 31 patients and good in 3. The ASAMI functional result was excellent in 27 patients, good in 6, and fair in 1.

Conclusions

Definitive management using the hexapod external fixator is an alternative and effective method for high-energy tibial shaft fractures, including technical advantages of early trauma-control, the versatility of achieving excellent alignment, and the continuity of device until bone union.