Biomechanical analysis of two fixation methods for proximal chevron osteotomy of the first metatarsal

Purpose

The proximal chevron osteotomy provides high correctional power. However, relatively high rates of dorsiflexion malunion of up to 17 % are reported for this procedure. This leads to insufficient weight bearing of the first ray and therefore to metatarsalgia. Recent biomechanical and clinical studies pointed out the importance of rigid fixation of proximal metatarsal osteotomies. Therefore, the aim of the present study was to compare biomechanical properties of fixation of proximal chevron osteotomies with variable locking plate and cancellous screw respectively.

Methods

Ten matched pairs of human fresh frozen cadaveric first metatarsals underwent proximal chevron osteotomy with either variable locking plate or cancellous screw fixation after obtaining bone mineral density. Biomechanical testing included repetitive plantar to dorsal loading from 0 to 31 N with the 858 Mini Bionix^® (MTS^® Systems Corporation, Eden Prairie, MN, USA). Dorsal angulation of the distal fragment was recorded.

Results

The variable locking plate construct reveals statistically superior results in terms of bending stiffness and dorsal angulation compared to the cancellous screw construct. There was a statistically significant correlation between bone mineral density and maximum tolerated load until construct failure occurred for the screw construct (r = 0.640, p = 0.406).

Conclusion

The results of the present study indicate that variable locking plate fixation shows superior biomechanical results to cancellous screw fixation for proximal chevron osteotomy. Additionally, screw construct failure was related to levels of low bone mineral density. Based on the results of the present study we recommend variable locking plate fixation for proximal chevron osteotomy, especially in osteoporotic bone.     

Cortical bone pin fixation: a preliminary report on fixation of digital arthrodeses and distal chevron first metatarsal osteotomies.

From 1998 to 1999, the senior author utilized Allofix cortical bone pins for primary fixation of 40 first metatarsal distal chevron osteotomies and 30 digital arthrodeses in 42 patients. Radiographs of each patient were evaluated for the presence of graft incorporation, union of the osteotomy or fusion site, and postoperative migration of the osseous segments. In 70 procedures, the average time for graft incorporation as evaluated by the absence of graft visualization on radiographs was 4 months. Complications included one case of graft displacement. The results indicate that Allofix cortical bone pins are a reliable, safe, and effective method for the fixation of first metatarsal distal chevron osteotomies and phalangeal arthrodeses of the foot.     

Results of bioabsorbable fixation of metatarsal osteotomies

Biodegradable rods of self-reinforcing polylevolactic acid were used for fixation in 51 consecutive distal chevron osteotomies correcting for mild to moderate hallux valgus. Charts were retrospectively reviewed specifically for sterile sinus formation, wound complications, infection, and symptom recurrence. Radiographs obtained at most recent follow-up were evaluated for osteolysis and fixation failure. Hallux valgus angle, intermetatarsal angle, and distal metatarsal articular angle were measured preoperatively and postoperatively. Given the data presented here, we conclude that these implants can be used for fixation of distal chevron metatarsal osteotomies and that clinical results and patient satisfaction are excellent.     

Single absorbable polydioxanone pin fixation for distal chevron bunion osteotomies

The distal chevron osteotomy is a well-established technique for correction of symptomatic mild to moderate metatarsus primus varus with hallux valgus deformity. Fixation of the osteotomy ranges from none to bone pegs, Kirschner wires, screws, or absorbable pins. We evaluated one surgeon's (J.K.D.) results of distal chevron osteotomy fixation with a single, nonpredrilled, 1.3-mm poly-p-dioxanone pin and analyzed any differences in patients with unilateral or bilateral symptomatic metatarsus primus varus with hallux valgus deformities. All osteotomies healed without evidence of infection, osteolysis, nonunion, or necrosis. Equal correction was achieved in unilateral and bilateral procedures. The technique is quick and easy, and adequate fixation is achieved.     

Compression screw fixation in proximal first metatarsal osteotomies for metatarsus primus varus: initial observations.

Many methods of fixation have been used after proximal abductory metatarsal osteotomies for the correction of metatarsus primus varus. The methods include external immobilization and the application of devices such as stainless steel wire, Kirschner wires, staples, and compression plates. We have combined external immobilization with compression screw fixation across the osteotomy site. Two different types of screws were used: 1) an AO screw 3.6 mm. wide and 26 to 28 mm. long and 2) a standard Woodruff screw 3.5 mm. wide and 31.8 to 44.4 mm long. Twenty-two procedures were reviewed. When we compared the results, we found the AO screw to be superior in the degree of rigid fixation which it provides, as judged by the extent of postoperative callus formation.     

Supplementary axial Kirschner wire fixation for crescentic and Ludloff proximal metatarsal osteotomies: a biomechanical study

BACKGROUND: Loss of reduction of proximal metatarsal osteotomies may result from poor bone quality, suboptimal fixation, and limitations inherent in the bony geometry of the osteotomy. This study evaluated the mechanical benefit of adding two supplementary Kirschner wires to the crescentic and Ludloff osteotomies. METHODS: Eleven and 10 matched pairs of cadaver foot specimens were used for the Ludloff and the proximal crescentic metatarsal osteotomies, respectively. Each metatarsal head specimen was then loaded to failure using a servohydraulic MTS Mini Bionix test frame (MTS Systems Corp, Eden Prairie, MN), and the failure gap was measured with an extensometer. To account for variable bone quality in the study specimens, the failure loads were normalized with the measured bone mineral density (BMD) values of the metatarsal specimens. A paired Student's t-test analysis was used to compare the failure loads between the specimens with the conventional osteotomies and the osteotomies supplemented with two axial Kirschner wires. RESULTS: The load-to-failure of the Ludloff osteotomy with two screws and with one proximal screw and two Kirschner wires was 858.5 N cm(2)/gm and 692.3 N cm(2)/gm, respectively (p > 0.05). The average load-to-failure of crescentic osteotomy with one screw and two axial Kirschner wires (458.8 N cm(2)/gm) was significantly higher than the strength of crescentic osteotomy fixed with one screw only (367.5 N cm(2)/gm) (p = 0.05). For the Ludloff osteotomy, 16 specimens (72.7%) failed by more than 2 mm of gapping. The crescentic osteotomy failures included 16 2-mm gap failures (80%). The Ludloff osteotomy showed a trend toward increased fixation stability as compared with both crescentic osteotomy constructs. CONCLUSION: The use of two supplemental axial Kirschner wires offers a simple and effective means to improve the initial mechanical stability of the proximal crescentic osteotomy and can be used in the standard Ludloff osteotomy to replace the second screw when screw purchase is poor without significant loss of fixation strength. The possible advantage of Kirschner wire flexibility in restoring position after gapping of the osteotomy site should be investigated.     

Stability and fixation techniques in first metatarsal osteotomies.

Osteotomy of the first metatarsal is a common procedure for correction of hallucal disease. Metatarsals are unique in that they are the only long bones in the human body that support load perpendicular to their longitudinal axis during standing. Thus, osteotomy of the first metatarsal may be complicated by loss of fixation, resulting in nonunion or malunion. The authors review the forces that must be resisted by the osteotomy of the first metatarsal as postoperative weight bearing is initiated, and explore the principles of osteotomy geometry and different fixation techniques to maximize stability of the final construct and to minimize the risk of displacement.     

Biomet reunite absorbable fixation in lesser metatarsal chevron shortening osteotomy: A new fixation technique

A procedure to fixate lesser metatarsal osteotomies with absorbable internal fixation is presented. This method may help prevent metatarsal head and toe elevatus.     

The use of intramedullary devices for fixation of metatarsal osteotomies in hallux valgus surgery – A systematic review

BackgroundHallux valgus is a common foot condition with numerous surgical techniques described. Minimally invasive surgery is becoming more popular, with resultant development of suitable fixation devices. The aim of this systematic review was to evaluate the evidence on the use of intramedullary devices in hallux valgus first metatarsal corrective osteotomies, and describe clinical and radiological outcomes, with an overview of techniques and implants used.MethodsWe searched PubMed, Medline, Embase and EMCare databases, conforming to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Radiological outcomes including the hallux valgus angle (HVA) and intermetatarsal angle (IMA) were recorded, as well as clinical outcome scores and complications. Methodological quality of included studies was assessed using the MINORS score.ResultsTen studies were included, comprising 696 feet in 745 patients. Data pooling and metanalysis was not possible due to overall low quality of evidence. Four implants were reported (Endolog, ISO Plate, V-Tek Plate, Link Fixator) and used with distal first metatarsal osteotomies, with improvement in HVA, IMA, and clinical outcome scores comparable to other fixation techniques. There were no reported cases of non-union. Complication rates were variable (all cause range of 0–21%) across all studies, with an overall low rate.ConclusionIntramedullary devices are viable and safe to use for hallux valgus first metatarsal osteotomies, with comparable radiological and functional outcomes to other techniques. Current evidence base is of low methodological quality, therefore high quality studies are required to further evaluate these devices.     

Angular correction and complications of proximal first metatarsal osteotomies for hallux valgus deformity

Purpose

Proximal first metatarsal osteotomies are recommended for the surgical treatment of moderate to severe hallux valgus deformity. This study aimed to compare correction of intermetatarsal and hallux valgus angles and complications of proximal crescentic, Ludloff, proximal opening wedge, proximal closing wedge, proximal chevron and other proximal first metatarsal osteotomies.

Methods

A systematic search for the keywords “(bunion OR hallux) AND (proximal OR crescentic OR basilar OR opening OR closing OR shelf OR Ludloff) AND osteotomy” in the online databases MEDLINE, Embase, CINAHL, Cochrane Central Register of Controlled Trials and Cochrane Database of Systematic Reviews was performed.

Results

There was a mean correction of hallux valgus angle of 20.1° [confidence interval (CI) 18.7–21.4] and of intermetatarsal angle of 8.1° (CI 7.7–8.9). The overall complication rate reached 18.7 %.

Conclusions

The results of this study reveal higher corrective power of proximal osteotomies compared to meta-analysis data on diaphyseal osteotomies.     

Early results using a biodegradable magnesium screw for modified chevron osteotomies

This is the first larger study analyzing the use of magnesium‐based screws for fixation of modified Chevron osteotomies in hallux valgus surgery. Forty‐four patients (45 feet) were included in this prospective study. A modified Chevron osteotomy was performed on every patient and a magnesium screw used for fixation. The mean clinical follow up was 21.4 weeks. The mean age of the patients was 45.5 years. Forty patients could be provided with the implant, in four patients the surgeon decided to change to a standard metallic implant. The AOFAS, FAAM and pain NRS‐scale improved markedly. The hallux valgus angle, intermetatarsal angle and sesamoid position improved significantly. Seven patients showed dorsal subluxation, rotation or medial shifting of the metatarsal heads within the first 3 months. One of these patients was revised, in all others the findings were considered clinically not significant or the patients refused revision. This study shows the feasibility of using magnesium screws in hallux valgus‐surgery. Surgeons starting with the use of these implants should be aware of the proper handling of these implants and should know about corrosion effects during healing and its radiographic appearance. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:2207–2214, 2016.     

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

BackgroundDistal 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.MethodsEighteen 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.ResultsIn 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 235 N (±128 N) in group 1 and 210 N (±107 N) in group 2 (p = 0.47).ConclusionsThe 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.     

可吸收棒在拇外翻第1跖骨基底截骨治疗的应用

目的探讨可吸收棒在拇外翻第1跖骨基底楔形截骨术中的应用疗效。方法对青中年中至重度拇外翻患者采用第1跖骨基底截骨结合拇趾骨赘切除、关节囊紧缩缝合 拇内收肌松解术,截骨端以可吸收棒交叉固定。结果53例(81足),随访3~16个月。采用美国足踝矫形学会拇外翻评分标准,平均HVA矫正17°,平均IMA矫正6°,优63足,良14足,差4足,优良率95%。结论截骨端采用可吸收棒交叉固定同金属螺钉相比能避免对软组织的刺激,安全有效,不需再次手术取出内固定。     

Principles of first metatarsal osteotomies.

Summarizing all the data while choosing the suitable procedure for hallux valgus deformity leads to classification of 3 main categories, which are based on the intermetatarsal angle (Table 1). Mild deformity has less than 15 degrees intermetatarsal angle, intermediate deformity has 15 degrees to 20 degrees intermetatarsal angle, and severe deformity has more than 20 degrees [table: see text] intermetatarsal angle. Every category may be divided further into low degree of DMAA (8 degrees) or high degree of DMAA (> 15 degrees). When choosing the correct procedure, the length of the first metatarsal has to be considered. In short first metatarsals, base angular osteotomies lead to further shortening of the metatarsal. Displacement osteotomies are preferred. In mild deformity, a distal osteotomy can be performed. If a mild deformity has a high DMAA, it can be corrected by a distal rotated chevron osteotomy. Intermediate deformity with a normal DMAA can be corrected by displacement osteotomies, and high DMAA can be corrected by rotated scarf of double osteotomy, which includes a base osteotomy to correct the intermetatarsal angle and a distal osteotomy, such as Riverdin, to correct the DMAA. Severe deformity can be corrected only by angular osteotomies. Inherently, these osteotomies increase the DMAA; they can be performed only in normal DMAA. Only a base angular osteotomy and distal rotation osteotomy can correct high levels of DMAA in severe intermetatarsal angles.     

Mobility changes of the first ray after hallux valgus surgery: clinical results after proximal metatarsal chevron osteotomy and distal soft tissue procedure

BACKGROUND: The purpose of this study was to evaluate the change of the first ray mobility after PMCO and DSTP in hallux valgus patients. MATERIALS AND METHODS: From May 2004 to December 2005, 82 PMCO with DSTP surgeries were performed for the management of hallux valgus deformity. The dorsiflexion mobility of the first ray of the foot was measured both preoperatively and 1 year after surgery using a modified Klaue device. The data were statistically analyzed with a paired t-test. An American Orthopedic Foot and Ankle Society (AOFAS) forefoot hallux score and patient satisfaction were also evaluated. RESULTS: Subjects consisted of 9 male and 73 female patients with an average age of 47.7 years (range, 19 to 74 years). The mean preoperative dorsiflexion mobility was 6.8 (range, 2.32 to 15.02) mm and the mean dorsiflexion mobility at one year after operation was 3.2 (range, from 1.7 to 5.4) mm. This decrease was statistically significant (p < 0.01). The mean preoperative AOFAS forefoot hallux score was 66.2 (range, 44 to 90) and improved to 89.1 (range, 72 to 100) by the 1-year followup (p < 0.01). CONCLUSION: Clinically, the dorsiflexion mobility of the first ray was significantly reduced after correction of hallux valgus with PMCO with DSTP. Because the stability of the first ray can be improved with PMCO with DSTP, the surgical indication for this procedure could include some patients showing hypermobility of the first ray.     

Shortening of the first metatarsal as a complication of metatarsal osteotomies

There have been few reports of shortening of the first ray of the foot because of damage to the physis of the first metatarsal during the performance of metatarsal osteotomy for residual metatarsus adductus. In a retrospective study of twenty-seven feet in twenty patients who underwent this procedure, eight feet in seven patients were noted to have some degree of residual shortening of the first ray. This is an incidence of 30 per cent. The follow-up period after osteotomy ranged from two years to seven years and four months (average, four years). We could find no clear correlation between the occurrence of shortening and the patient's age at osteotomy, sex, or race, or the etiology of the adduction for which the osteotomy had been done. A clear correlation was found, however, with the surgical technique that had been employed. In two of the eight feet with a short first ray, the osteotomy had been done within the physis of the first metatarsal. In the other feet the procedure had employed an osteotomy site close to the physis or extensive periosteal dissection, or both. The results in our patients implicate subperiosteal dissection of the first metatarsal as an important, previously unreported cause of damage to the physis and of the resultant shortening. We recommend radiographic determination of the relationship of the osteotomy site to the physis before dissection is performed.