The influence of patient age and bone mineral density on osteotomy fixation stability after hallux valgus surgery: A biomechanical study

Health-related quality-of-life improvement after hallux valgus corrective surgery

BACKGROUND

Hallux valgus is a common forefoot deformity that affects function of foot and quality of life (QoL). This study aims to identify factors associated with clinically important improvements in QoL after hallux valgus corrective surgery.

METHODS

A retrospective analysis on 591 cases of hallux valgus corrective surgery performed between 2007 and 2013 was conducted. Patients' preoperative and 2-year postoperative Physical Component Score (PCS) and Mental Component Score (MCS) were compared to identify the presence of clinically significant improvements in patient-reported QoL. A multiple logistic regression model was developed through a stepwise variable-selection model building approach. Age, BMI, preoperative patient reported outcome score, PCS, MCS, pain score, gender, side of surgery, type of surgery, and presence of lesser toe deformities or metatarsalgia were considered.

RESULTS

Median PCS significantly improved from 49 to 53 (p < 0.001), and median MCS remained at 56 (p = 0.724). Age, preoperative MCS and PCS were independent predictors for significant improvements of PCS at 2-year postoperatively.

CONCLUSION

Three groups of patients were more likely to have significant QoL improvements after hallux valgus corrective surgery. These were the younger patients, those with better preoperative mental health or those with poorer preoperative physical health.

LEVEL OF EVIDENCE

III.

Scarf osteotomy for the treatment of moderate to severe hallux valgus: Analysis of predictors for midterm outcomes and recurrence

BACKGROUND

Controversies remain regarding the predictors for outcomes and recurrence after scarf osteotomy for hallux valgus deformity.

METHODS

Sixty-two patients (70 feet) underwent scarf osteotomy for hallux valgus deformity. The radiological angles, tibial sesamoid position, articular congruence, demographics, comorbidities, AOFAS, VAS and SF-12 scores, and the postoperative compliance were tested as predictors for outcomes and recurrence.

RESULTS

After a mean 38±15.4 months follow-up, all of the radiological angles, the total AOFAS, PCS-12 and VAS scores significantly improved (all P<0.001). Preoperative MCS-12 was directly related to the total postoperative AOFAS score (P=0.003). A higher number of cardiovascular risk factors negatively affected the postoperative total AOFAS score, VAS and PCS-12 (β=-3.42, P=0.030; β=0.262, P=0.022; β=-0.181, P=0.025, respectively). The BMI influenced postoperative PCS-12 (β=-0.244, P=0.002). Preoperative HVA was directly related to postoperative DMAA (P=0.002) and tibial sesamoid position (P=0.005). Preoperative joint incongruence and postoperative noncompliance were associated with recurrence (P=0.043 and P=0.035, respectively).

CONCLUSIONS

Satisfactory results can be expected after scarf osteotomy. Higher BMI and number of cardiovascular risk factors, and low mental status should be carefully considered when counselling patients for this procedure. Adherence to postoperative care instructions influences deformity recurrence.

Biomechanical comparison of conventional versus modified technique in distal chevron osteotomies of the first metatarsal: A cadaver study

BACKGROUND

Distal chevron osteotomy can be performed using a conventional or a modified technique. The aim of this biomechanical study was to compare the stability of the two techniques.

METHODS

Eighteen first metatarsals from nine pairs of fresh frozen human cadaver feet were used. A distal chevron osteotomy was performed using the conventional technique in group 1 (n=9) and using the modified technique in group 2 (n=9). The head of the first metatarsals was loaded in two different configurations (cantilever and physiological), using a materials testing machine.

RESULTS

In the cantilever configuration, the relative stiffness of the osteosynthesis in comparison with intact bone was 60% (±21%) in group 1 and 65% (±25%) in group 2 (p=0.61). In the physiological configuration, it was 47% (±29%) in group 1 and 47% (±21%) in group 2 (p=0.98). The failure strength in the cantilever configuration was 235N (±128N) in group 1 and 210N (±107N) in group 2 (p=0.47).

CONCLUSIONS

The conventional and the modified technique for distal chevron osteotomy in the treatment of hallux valgus show a comparable biomechanical loading capacity in this cadaver study.

Biomechanical Comparison of Fixation With a Single Screw Versus Two Kirschner Wires in Distal Chevron Osteotomies of the First Metatarsal: A Cadaver Study

Distal chevron osteotomy is a common procedure for surgical correction of hallux valgus. Osteosynthesis with 1 screw or 2 Kirschner wires has been commonly used. We compared the stability of the 2 techniques in distal chevron osteotomy. Sixteen first metatarsals from fresh-frozen human cadaver feet (9 different cadaveric specimens) were used. A standardized distal chevron osteotomy was performed. One first metatarsal from each pair was assigned to group 1 (3.5-mm cortical screw; n = 8) and one to group 2 (two 1.6-mm Kirschner wires; n = 8). Using a materials testing machine, the head of the first metatarsals was loaded in 2 different configurations (cantilever and physiologic) in succession. In the cantilever configuration, the relative stiffness of the osteosynthesis compared with intact bone was 59% ± 27% in group 1 and 68% ± 18% in group 2 (p = .50). In the physiologic configuration, it was 38% ± 25% in group 1 and 35% ± 7% in group 2 (p = .75). The failure strength in the cantilever configuration was 187 ± 105 N in group 1 and 259 ± 71 N in group 2 (p = .21). No statistically significant differences were found in stability between the 2 techniques. The use of 1 screw or 2 Kirschner wires had no significant differences in their biomechanical loading capacity for osteosynthesis in distal chevron osteotomies for treatment of hallux valgus.

Immediate Weight Bearing After Hallux Valgus Correction Using Locking Plate Fixation of the Ludloff Osteotomy: A Retrospective Review

BACKGROUND

A Ludloff osteotomy is a common procedure used to correct hallux valgus deformities. Traditionally, the osteotomy is stabilized with screws only, thus requiring the patient to be non-weight bearing until healed. There have been no outcome studies analyzing immediate weight bearing after Ludloff osteotomy for hallux valgus.

METHODS

Of the 350 patients (390 feet) who underwent a Ludloff osteotomy fixed with a locking plate and prescribed an immediate weight-bearing postoperative protocol, 288 patients (326 feet) were included in the analysis. Average radiographic follow-up was 8 months, and hallux-valgus angle (HVA), intermetatarsal angle (IMA), and any hardware failures or hypertrophic callus formation were recorded. The Foot Function Index (FFI) was assessed in 103 patients at an average of 44 months postoperatively.

RESULTS

Average IMA and HVA correction were 7.6° and 21.6°, respectively (P < .0001). Loss of HVA and IMA correction of 4.6° and 2.3°, respectively, were noted between the initial postoperative films and final weight-bearing films. The average FFI score calculated for the 103 respondents was 10.4 out of a possible 100, indicating relatively low pain and disability. Complication rates were consistent with most other published postoperative protocols, with the most commonly seen being superficial infection (4.9%) and symptomatic hardware (4.6%).

CONCLUSION

An immediate weight-bearing protocol for Ludloff osteotomies fixed with locking plates results in recurrence rates that are similar to those found with other protocols. Patient function is quite high and pain low following this protocol. The most commonly observed complications were superficial infection and symptomatic hardware requiring removal.

LEVELS OF EVIDENCE

Level IV.

Supplementary medial locking plate fixation of Ludloff osteotomy versus sole lag screw fixation: A biomechanical evaluation

BACKGROUND

The Ludloff oblique osteotomy is inherently unstable, which might lead to delayed union and loss of correction. Supplementary fixation to two lag screw fixation has been proposed. The hypothesis is that the osteotomy fixation constructs supplemented by a mini locking plate provide greater resistance to osteotomy gaping and loss of angular correction in response to cyclic loading.

METHODS

Twenty fourth generation composite 1st metatarsals were used and underwent a Ludloff osteotomy. They were divided in two fixation groups: two lag screws (Group A), and with a supplementary mini locking plate (Group B). Specimens were subjected to either monotonic loading up to failure or to fatigue (cyclic) tests and tracked using an optical system for 3D Digital Image Correlation.

FINDINGS

The osteotomy gap increased in size under maximum loading and was significantly greater in Group A throughout the test. This increase was observed very early in the loading process (within the first 1000cycles). The most important finding though, was that with the specimens completely unloaded the residual gap increase was significantly greater in Group A after only 5000cycles of loading up to the completion of the test. The lateral angle change under maximum loading was also significantly greater in Group A throughout the test, with that increase observed early in the loading process (5000cycles). With the specimens completely unloaded the residual lateral angle change was also significantly greater in Group A at the completion of the test.

INTERPRETATION

Supplementary fixation with a mini locking plate of the Ludloff osteotomy provided greater resistance to osteotomy gaping and loss of angular correction compared to sole lag screws, in response to cyclic loading.

Influences of geometrical and mechanical properties of bone tissues in mandible behaviour - experimental and numerical predictions

The properties and geometry of bone in the mandible play a key role in mandible behaviour during a person's lifetime, and attention needs to be paid to the influence of bone properties. We analysed the effect of bone geometry, size and bone properties in mandible behaviour, experimenting on cadaveric mandibles and FE models. The study was developed using the geometry of a cadaveric mandible without teeth. Three models of cadaveric condyles were experimentally tested with instrumented with four rosettes, and a condyle reaction of 300 N. Four finite element models were considered to validate the experiments and analyse mandible behaviour. One numeric model was simulated with 10 muscles in a quasi-static condition. The experimental results present different condyle stiffness's, of 448, 215 and 254 N/mm. The values presented in the rosettes are influenced by bone geometry and bone thickness; maximum value was -600 με in rosette #4, and the maximum strain difference between mandibles was 111%. The numerical results show that bone density decreases and strain distribution increases in the thinner mandible regions. Nevertheless, the global behaviour of the structure remains similar, but presents different strain magnitudes. The study shows the need to take into account bone characteristics and their evolutions in order to improve implant design and fixation throughout the patient life. The change in bone stiffness promotes a change in maximum strain distribution with same global behaviour.