Mitchell's osteotomy with mini-plate and screw fixation for hallux valgus

Effect of Displacement Degree of Distal Chevron Osteotomy on Metatarsal Stress: A Finite Element Method

BACKGROUND

The stress of foot bone can effectively evaluate the functional damage caused by foot deformity and the results of operation. In this study, the finite element method was used to investigate the degree of displacement of distal chevron osteotomy on metatarsal stress and metatarsophalangeal joint load; Methods: Four finite element models of displacement were established by using the CT images of a patient with moderate hallux valgus (hallux valgus angle and intermetatarsal angle were 26.74° and 14.09°, respectively), and the validity of the model was verified. Each finite element model consisted of bones and various cartilage structures, ligaments, and plantar fascia, as well as encapsulated soft tissue. Except for soft tissue, the material properties of other parts were isotropic linear elastic material, and the encapsulated soft tissue was set as nonlinear hyperelastic material. The mesh was tetrahedral mesh. Link elements were used in ligament and plantar fascia. A ground reaction force with a half-body weight was applied at the bottom of the floor to simulate the ground reaction when standing. The upper surfaces of the encapsulated soft tissue, distal tibia, and distal fibula were fixed. The stress distribution of metatarsals and the stress of cartilage of the first metatarsophalangeal joint were compared and analyzed; Results: Compared with the hallux valgus without osteotomy, the stress of the first metatarsals and second metatarsals of 2-4 mm decreased, and the stress of the interarticular cartilage of the first metatarsophalangeal joint with 4 mm was reduced. In the case of 6 mm, the stress value between the first metatarsal and the first metatarsophalangeal joint increased, and 4 mm was the most suitable distance; Conclusions: Compared with the hallux valgus without osteotomy, the stress of the first metatarsals and second metatarsals of 2-4 mm decreased, and the stress of the interarticular cartilage of the first metatarsophalangeal joint with 4 mm was reduced. In the case of 6 mm, the stress value between the first metatarsal and the first metatarsophalangeal joint increased, and 4 mm was the most suitable distance. For the degree of displacement of the distal chevron osteotomy, the postoperative stability and the stress distribution of metatarsal bone should be considered. Factors such as hallux valgus angle, intermetatarsal angle, patient's age, body weight, and metatarsal width should be considered comprehensively. The factors affecting osteotomy need to be further explored. The degree of displacement of osteotomy can be evaluated by FE method before the operation, and the most suitable distance can be obtained.

Modified Mitchell technique for treating hallux valgus: Retrospective case series on a Middle-Eastern population and literature review

Introduction

The hallux valgus deformity is a complex deformity of the first ray of the foot, with more than 100 procedures developed for its treatment. The aim of this retrospective study was to assess the clinical and radiographic outcomes of a modified Mitchell's technique.

Methods

Between 2007 and 2018, 75 patients underwent the procedure. Clinical results were assessed by the AOFAS score. Radiological studies were evaluated by measuring pre-operative and post-operative HVA and IMA angles as well as the relative shortening of the first metatarsal.

Results

Of the initial 75 patients, 42 patients remained eligible with a total of 67 feet. The mean age and follow-up were 47.8 and 5.2 years respectively. Global AOFAS score improved from 45.3 to 88.8 (p < 0.01). Mean HVA and IMA improved from 37.0 to 10.2 (p < 0,01) and 12.1 to 5.6 (p < 0.01), respectively. The mean metatarsal shortening was 3.0 mm (p < 0.01). The statistical analysis showed no significant correlation between preoperative HVA and IMA angles with postoperative shortening, metatarsalgia, AOFAS scores nor the difference between the preoperative and postoperative AOFAS scores.

Conclusion

Short- and long-term outcomes of this modified Mitchell's osteotomy have been reported. Compared to other studies, these modifications proved to result in very good clinical and radiological outcomes even in severe cases with HVA>40. It has shown to be reliable, reproducible, and cost-efficient with low complication rates. We would like to highlight the importance of proper patient selection, limited soft tissue stripping, and adherence to the proposed surgical steps to avoid unwanted complications.

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The Modified Mitchell Technique has been shown to be reliable, reproducible, and cost-efficient with low complication rates.

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The addition of intra-articular lateral soft tissue release, preventing a lateral incision, decreasing wound and soft tissue complications.

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The use of autologous bone graft adjacent to the osteotomy stump helps improve union.

The effect of hallux valgus open and percutaneous surgery on AOFAS scale: a systematic review and meta-analysis

PURPOSE

To estimate the comparative effect of open and percutaneous hallux valgus (HV) surgery on patients' quality of life (QoL) using the American Orthopedic Foot and Ankle Society (AOFAS) scale including total score and individual domains (pain, function, and alignment).

METHODS

MEDLINE, EMBASE, Cochrane Library, and Web of Science databases were systematically searched from inception to March 2020 for studies on the effect of HV surgery on patients' QoL using the AOFAS score. A standardized mean difference score was calculated on the total AOFAS score and on each AOFAS domain (pain, function, and alignment) using Cohen's d index.

RESULTS

Considering the 53 published studies included, the pooled effect size (ES) estimates for the AOFAS total score were 3.69 (95% CI 3.37-4.01; I² = 95.5%) for open surgery and 3.40 (95% CI 2.99-3.80, I² = 88.2%) for percutaneous surgery. The total pooled ES estimate was 3.61 (95% CI 3.35-3.87, I² = 94.5%). Considering the pain domain, the pooled ES estimates were 2.21 (95% CI 1.98-2.43, I² = 64%) for open surgery and 2.52 (95% CI 1.83-3.20, I² = 92.6%) for percutaneous surgery. For the function domain, the pooled ES estimates were 1.37 (95% CI 0.93-1.81, I² = 91%) for open surgery and 2.28 (95% CI 1.10-3.47, I² = 96.8%) for percutaneous surgery. Finally, the pooled ES estimates for the alignment domain were 3.99 (95% CI 3.51-4.47, I² = 85.7%) for open surgery and 2.66 (95% CI 2.23-3.09, I² = 78.5%) for percutaneous surgery.

CONCLUSION

Our data support that HV surgery increases the total AOFAS score as well as the AOFAS scores by domain (pain, function, and alignment). Furthermore, our data show that HV surgery increases patients' QoL, after both open and percutaneous surgery, without differences between them.

Mechanical Testing of Maximal Shift Scarf Osteotomy with Inside-Out Plating Compared to Classic Scarf Osteotomy With Double Screw Fixation

The purpose of the present study was to biomechanically compare the primary stability of our formerly described inside-out plate fixation to the classic double screw fixation for scarf osteotomy in the treatment of hallux valgus. We performed 20 scarf osteotomies on first metatarsal composite bone models. One half were fixed using a double screw technique and the other half using a locking plate inside-out technique. Using a testing device to simulate the physiologic load, the specimen was loaded until failure, and the load at failure, displacement at failure, and work at failure were recorded. The results were compared between the 2 groups and against the findings from intact sawbones. Compared with the intact bone models, the energy absorption was low for both types of osteotomy fixation. Between the 2 fixation groups, the load at failure was greater for plate fixation, although the difference was not statistically significant (p = .051). However, a statistically significant difference was found between both groups comparing work and displacement at failure (p < .001). In conclusion, the formerly described inside-out plating technique is a biomechanically reasonable alternative to screw fixation because of its primary stability after scarf osteotomy for hallux valgus.