Strength of fixation of Ludloff metatarsal osteotomy utilizing three different types of Kirschner wires: a biomechanical study

Biomechanical comparison of reverse offset-L osteotomy and chevron osteotomy in cadaveric hallux valgus surgery

OBJECTIVE

Chevron osteotomy offers near-excellent clinical results and adequate stability at lower shift percentages, among the techniques used to correct hallux valgus deformity. This cadaveric study aimed to compare the Chevron osteotomy with the reverse offset-L osteotomy, which may provide a greater surface area and a more stable geometry to withstand higher cantilever forces at higher shift percentages.

METHODS

Metatarsal bones obtained from 20 human cadavers with similar bone quality were divided into two groups: Chevron osteotomy was applied to the 1st group and reverse offset-L osteotomy was applied to the 2nd group. The load-to-failure, displacement in the y-axis, and total displacement values of both groups were compared statistically. Furthermore, bone densities were compared between the groups with computed tomography imaging.

RESULTS

When outliers in both groups were excluded, a statistically significant difference was found in favor of reverse offset-L (143 ± 42 vs. 204 ± 51.2 N, p = 0.02) in terms of failure load. The groups were similar in terms of displacement on the y-axis and total displacement values. Bone densities were similar.

CONCLUSION

The reverse offset-L osteotomy has been shown to withstand greater loads before failure compared to the standard Chevron osteotomy. This significant difference in load-to-failure may enable reverse offset-L to provide reliable stability in osteotomies performed in advanced HV cases requiring higher shifts.

Rotational and opening wedge basal osteotomies

There are more than 150 different procedures described for correction of the hallux valgus deformity, the treatment of which is usually guided by severity. Moderate to severe hallux valgus has traditionally been managed with a shaft or proximal osteotomy together with distal soft-tissue release. Proximal osteotomies can be classified as translation or rotational. Rotational osteotomies such as the Ludloff and proximal opening wedge have not been popular historically because of instability from lack of fixation, resulting in complications. This article describes modified techniques with modern fixation of these 2 osteotomies, which offer stable fixation and reproducible results.

The Ludloff osteotomy: a review of current concepts

The Ludloff osteotomy is a technique option to address hallux valgus in patients with a moderately to significantly increased first-second intermetatarsal angle. The Ludloff osteotomy is an oblique osteotomy of the first metatarsal extending dorsal-proximal to plantar-distal when viewed in the sagittal plane. The dorsal-proximal portion of the metatarsal is cut with the saw while maintaining the plantar-distal surface intact. A screw is inserted across the proximal aspect of the osteotomy, then the osteotomy is extended across the plantar surface distally. The metatarsal is rotated around the axis of the screw to the desired correction. In order to perform the osteotomy correctly, the surgeon must not only effectively complete the nuances of the technique, but also understand the limitations and contraindications of the Ludloff osteotomy. This review of current concepts for the Ludloff osteotomy reviews recent literature as well as technique pearls and pitfalls in the application of this powerful osteotomy.

Additional surgical factors affecting the recurrence of hallux valgus after Ludloff osteotomy

We reviewed 91 patients (103 feet) who underwent a Ludloff osteotomy combined with additional procedures. According to the combined procedures performed, patients were divided into Group I (31 feet; first web space release), Group II (35 feet; Akin osteotomy and trans-articular release), or Group III (37 feet; Akin osteotomy, supplementary axial Kirschner (K-) wire fixation, and trans-articular release). Each group was then further subdivided into severe and moderate deformities.

The mean hallux valgus angle correction of Group II was significantly greater than that of Group I (p = 0.001). The mean intermetatarsal angle correction of Group III was significantly greater than that of Group II (p < 0.001). In severe deformities, post-operative incongruity of the first metatarsophalangeal joint was least common in Group I (p = 0.026). Akin osteotomy significantly increased correction of the hallux valgus angle, while a supplementary K-wire significantly reduced the later loss of intermetatarsal angle correction. First web space release can be recommended for severe deformity. Additionally, K-wire fixation (odds ratio (OR) 5.05 (95% confidence interval (CI) 1.21 to 24.39); p = 0.032) and the pre-operative hallux valgus angle (OR 2.20 (95% CI 1.11 to 4.73); p = 0.001) were shown to be factors affecting recurrence of hallux valgus after Ludloff osteotomy.

Cite this article: Bone Joint J 2013;95-B:803–8.

Cavovarus foot realignment to treat anteromedial ankle arthrosis

BACKGROUND

Adult patients with cavovarus feet were seen with symptomatic anteromedial ankle arthrosis and, frequently, lateral hindfoot instability. Static and dynamic realignment was performed to redistribute joint contact pressures and restore stability.

METHODS

Thirteen patients with fixed cavovarus feet (6 neurogenic, 7 idiopathic; 6 with hindfoot instability, 7 without) and mild to moderate anteromedial ankle arthrosis were treated by osteotomies and tendon transfers but no lateral ligament reconstruction. Anteromedial cheilectomy of the ankle was added to increase dorsiflexion and alleviate anteromedial impingement.

RESULTS

Failure occurred in 2 patients, who required additional procedures. The remaining 11 patients improved from preoperative 45 to 71 points (American Orthopaedic Foot and Ankle Society Ankle-Hindfoot Scale score) at the latest follow-up (average 84 months). Ankle dorsiflexion improved 7 degrees on average. There was no recurrent hindfoot instability and no progression of anteromedial ankle arthrosis over time.

CONCLUSION

Cavovarus foot realignment with anteromedial ankle cheilectomy reliably improved patients' symptoms related to ankle arthrosis, restored lateral hindfoot stability, and stabilized the extent of anteromedial ankle arthrosis when talar varus tilt was reduced.

LEVEL OF EVIDENCE

Level IV, retrospective case series.

Quantitative analysis of the long- and short-arm crescentic shelf bunionectomy osteotomies in fresh cadaveric matched pair specimens

Two variations of crescentic shelf osteotomies have been described for the treatment of moderate to severe hallux abductovalgus: a short arm and a long arm. This study tested the hypothesis that the short-arm osteotomy will have a greater moment to failure and angular stiffness than the long arm. Eighteen first metatarsal specimens were dissected from 9 matched pairs of fresh frozen cadaveric specimens. One metatarsal from each pair received a short-arm osteotomy, whereas the other received a long-arm osteotomy. Each osteotomy was fixed with 2 screws. The short arm was fixed with 1 oblique screw and 1 dorsal-to-plantar screw. The long arm was fixed with 2 dorsal-to-plantar screws: 1 at the proximal aspect and 1 at the distal aspect of the shelf. Each specimen was loaded in a materials testing machine to measure moment to failure and angular stiffness. The base of the first metatarsal was potted and load applied to the plantar aspect of the metatarsal head at a constant rate until failure of the osteotomy. The mean maximum moment to failure of the short arm was significantly greater than the long arm (2.04 ± 0.96 Newton meter [Nm] vs. 1.48 ± 0.67 Nm, P = .03). The mean angular stiffness was significantly greater for short arm versus long arm (23.8 ± 19.11 Nm/radian vs. 0.98 ± 9.08 Nm/radian, P = .01). We report statistically significant data supporting the short-arm crescentic shelf osteotomy to have a greater moment to failure and angular stiffness compared with the long-arm crescentic shelf osteotomy.

Biomechanical comparison of hallux valgus correction using the proximal chevron osteotomy fixed with a medial locking plate and the Ludloff osteotomy fixed with two screws

BACKGROUND

For moderate-to-severe hallux valgus deformities with a 1-2 intermetatarsal angle in excess of 15 degrees , a proximal first metatarsal osteotomy is indicated. The ideal osteotomy has yet to be defined, but should inherently limit the incidence of dorsal malunion and allow for early ambulation. The present study evaluates the mechanical integrity of two popular first metatarsal osteotomies.

METHODS

Ten matched pairs of fresh-frozen cadaveric first metatarsals were harvested. In one metatarsal from each pair, a Ludloff osteotomy was created and fixed with two cannulated 3.5mm screws. In the contralateral first metatarsal, a proximal chevron osteotomy was performed and subsequently fixed with a medially applied locking plate. All specimens were mounted within an Instron 1321 servohydraulic materials testing machine and subjected to a plantar-to-dorsal cantilever bending protocol for 1000 cycles.

FINDINGS

Two of ten Ludloff osteotomies failed prior to completion of 1000 loading cycles by fracture at the distal screw site, whereas six of ten proximal chevrons failed prior to the 1000th cycle. The mode of failure in this group was by cut-out of the plantar-proximal screw. The bending stiffness of the Ludloff osteotomy exceeded that of the proximal chevron at all measurement points between the 1st and 200th load cycles (P<0.05). After 200 cycles, an inadequate number of plate constructs survived to allow statistical comparison.

INTERPRETATION

The results of the present study indicate that the proximal chevron osteotomy fixed with a medially based locking plate exhibits mechanical properties inferior to those of the Ludloff osteotomy under the tested conditions.

Arthrodesis of the first metatarsocuneiform joint: a comparative study of fixation methods

BACKGROUND

The Lapidus bunionectomy is a popular procedure for severe bunion deformity where metatarsus primus varus is equal to or exceeds 15 degrees. We evaluated a new locking compression plate which may improve outcomes with the Lapidus procedure.

METHODS

Ten matched pairs of cadaver feet were used to compare the standard crossed 4.0-mm compression screw method of fixation to the LPS Lapidus plate. After performing the matched operations the cadaver constructs were stressed to failure using the INSTRON and Wavemaker software.

RESULTS

The LPS Lapidus plate load to failure was 108 Nm with a bending moment of 6.0 Nm. The crossed screw technique was inferior at 78 Nm with a bending moment of 4.4 Nm (p = 0.02)

CONCLUSION

Unlike other H-plates or locking plates, load to failure was higher with the Lapidus plate constructs.

CLINICAL RELEVANCE

The increased rigidity provided by these plates may help to minimize the risk of nonunion or malunion.

Lapidus bunionectomy: Early evaluation of crossed lag screws versus locking plate with plantar lag screw

We compared outcomes of the Lapidus bunionectomy fixated with crossed lag screws versus a locking plate with a plantar lag screw. Forty patients who underwent Lapidus bunionectomy between August 2001 and May 2006 were evaluated in a combined retrospective and prospective fashion. Crossed lag screws were used in 19 of the patients, and a locking plate with a plantar lag screw was used in 21 of the patients. Other than fixation, the only interventional difference pertained to postoperative weight bearing, where those receiving the plate initiated full weight bearing on the operated foot at 4 weeks postoperative, as compared to 6 weeks for those receiving crossed screws. Overall, the mean preoperative AOFAS hallux score was 41.75 +/- 2.52, and the postoperative score was 90.48 +/- 8.41 (P < .0001). The overall mean preoperative first intermetatarsal angle was 15.3 degrees +/- 2.32 degrees , and long term the angle was 5.03 degrees +/- 2.86 degrees (P < .0001). When comparisons were made based on the method of fixation, use of an adjunct Akin osteotomy and surgery performed before 2003 were statistically significantly associated with crossed screw fixation, and the preoperative AOFAS score was statistically significantly higher in the locking plate fixation group. There were no statistically significant differences related to postoperative complications between the 2 fixation groups. In conclusion, the Lapidus bunionectomy fixated with a locking plate and a plantar lag screw allows earlier weight bearing in comparison with crossed lag screws, without a difference in complications.

LEVEL OF CLINICAL EVIDENCE

2.

Biomechanical comparison of screws and plates for hallux valgus opening-wedge and Ludloff osteotomies

BACKGROUND

The optimal osteotomy type and fixation method for hallux valgus correction have not been defined. This study examined the mechanical properties of corrective opening-wedge and Ludloff oblique osteotomies under conditions approximating postoperative weight-bearing.

METHODS

Twenty-nine pairs of fresh-frozen metatarsals were divided into three groups. In Group 1, headless screws were compared with standard cortical screws for Ludloff osteotomy fixation. In Groups 2 and 3, Ludloff osteotomies fixed with headless screws were compared with opening-wedge osteotomies fixed with non-locking and locking plates, respectively. Constructs underwent dorsally-directed cantilever loading for 1000 cycles.

FINDINGS

No significant differences in angulation or stiffness were demonstrable in Group 1. In Group 2, Ludloff/headless screw construct stiffness exceeded non-locking plate construct stiffness. The mean angulation on the 1000th load cycle was greater for plates than for Ludloff/headless screws. In Group 3, locking plate construct stiffness and angulation did not differ from Ludloff/headless screws in early cyclic loading, but fixation failure of the locking plate constructs was common.

INTERPRETATION

The results indicate that screw type for Ludloff fixation may be left to surgeon preference and that opening-wedge plates exhibit mechanical properties inferior to that of the Ludloff osteotomy under the tested conditions. Lateral cortex continuity and bone density remain important factors in the performance of opening-wedge osteotomies.

Intra-articular radial head fracture in a child with an open physis: a case report

Fractures of the proximal end of the radius in children are uncommon. A case of fracture through the articular surface of the radial head (Salter-Harris type IV) in a 12-year-old boy is presented. Our paper recommends bone peg fixation in the treatment of Salter-Harris (S-H) type III or IV injuries in nearly skeletally mature.

Mechanical comparison of the Youngswick, sagittal V, and modified Weil osteotomies for hallux rigidus in a sawbone model

The purpose of this study was to compare the mechanical properties of 3 osteotomies often used for hallux rigidus. Maximum load, failure energy, stiffness, and fracture pattern were determined for 3 different test models as well as a control group. Twenty-eight first metatarsal polyurethane sawbone models were equally divided into 4 groups. The osteotomy groups tested consisted of a Youngswick, sagittal V, and modified Weil-type osteotomy of the first metatarsal. Each osteotomy was fixated with a 2.7-mm cortical screw, all 16 mm in length, and a small diameter smooth wire, both placed perpendicular to the osteotomy. Each model was then loaded to failure in a servo-hydraulic material testing machine. Results for maximum load to failure for all 4 constructs showed a mean range of 15.1 to 33.7 N, a mean energy to failure ranging from 0.04 to 0.8 J, and stiffness from 1.5 to 3.4 N/mm. Significant differences in peak load and stiffness (P = .015 for peak load, P = .025 for stiffness) were found between the sagittal V group versus the control and between the modified Weil and sagittal V group (P = .037 for peak load, P = .017 for stiffness). There were no significant differences in the energy to failure between the 4 groups (P > .083). These findings suggest that the sagittal V osteotomy construct was significantly weaker and less stiff than the modified Weil.

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.