Stability of Locking Plate and Compression Screws for Lapidus Arthrodesis: A Biomechanical Comparison of Plate Position

First cuneo-metatarsal arthrodesis (Modified Lapidus) with plantar plate for the treatment of hallux valgus: clinical and radiological outcomes at one year follow-up

INTRODUCTION

The modified Lapidus arthrodesis, involving the first cuneo-metatarsal joint, is a well-established surgical method and widely utilized for treating moderate to severe hallux valgus deformities with hypermobility in the first tarsometatarsal joint. The purpose of this study was to assess the rate of union following the Lapidus procedure using a plantar plate and an immediate full weight-bearing protocol. Secondary objectives included examining radiological corrections and potential associated complications.

METHODS

A retrospective study included 66 patients (80 feet) who underwent a modified Lapidus procedure for the treatment of hallux valgus associated with hypermobility of the first ray, performed by a single senior surgeon at our institution between May 2013 and November 2019. All patients had a minimum follow-up of 12 months. Patients were clinically assessed at 3 weeks, 3 months, and 1 year. Radiological measurements were taken on weight-bearing dorsoplantar views preoperatively, at 3 months, and at 12 months postoperatively.

RESULTS

Bone union was achieved in 79 cases (98.75%). There was one case of non-union, two wound complications (one infection and one dehiscence), two cases of symptomatic hardware requiring hardware removal, and one stress fracture associated with recurrence of hallux valgus that required revision. The mean hallux valgus angle (HVA) improved from 30.5 ° ±10.4 ° to 10.1 ° ±6.6 ° (p < .001), the mean intermetatarsal angle (IMA) improved from 13.4 ° ±3.6 ° to 5.6 ° ±2.9 (p < .001), The average sesamoid position improved from stage 5.9 ± 1.6 to stage 2.6 ± 1.2 (p < .001). The mean shortening of the first metatarsal was 3.6 mm ± 1.8. There was no significant difference between measurements at 3 and 12 months postoperatively.

CONCLUSION

Modified Lapidus with a planter plate and compression screw is a reliable method of fixation with a high union rate, permit an immediate protected weight bearing and a low complications rate.

LEVEL OF EVIDENCE

IV; Retrospective study.

Immediate Weightbearing after Modified Lapidus Arthrodesis Using a Medial Plate: A Retrospective Descriptive Cohort Study

The modified Lapidus procedure has emerged as a versatile solution for various pedal pathologies, particularly hallux abducto valgus. There have been numerous modifications over time regarding fixation techniques, joint preparation methods, graft utilization, and weightbearing protocols. However, concerns persist regarding prolonged nonweightbearing postoperatively, prompting the need for alternative approaches. This retrospective descriptive cohort analysis assessed the outcomes of 40 feet from 34 patients who underwent the modified Lapidus procedure with a medial plating system, aimed to evaluate immediate weightbearing outcomes on union rate, fixation-related complications, and functional outcomes. Among the 40 feet, findings showed a 95% (38/40) union rate within 6 months, with 2.5% (1/40) experiencing delayed union and 2.5% (1/40) facing fixation-related complications. There is a single case of malunion in the cohort. Additionally, statistically significant improvements were observed across all domains of the Manchester-Oxford Foot Questionnaire at p < .001. These findings suggest immediate weightbearing as a potential alternative to traditional nonweightbearing protocols. However, the study's retrospective nature and lack of a comparative group warrant cautious interpretation. Further research is essential to validate these findings and refine postoperative care protocols. By challenging conventional practices, this study underscores the complexity of optimizing patient outcomes in modified Lapidus procedure management. Tailored approaches and prospective investigations are imperative for establishing definitive guidelines and enhancing surgical techniques in this domain.

Tension Side Fixation for Lapidus Arthrodesis: A Retrospective Analysis

Moderate to severe hallux valgus deformity often requires a Lapidus procedure (first-tarsometatarsal arthrodesis). Traditional methods include a dorsal approach with dorsal or medial fixation. However, studies demonstrate plantar/tension-side fixation, provides superior load to failure and fixation strength. This could improve outcomes, address comorbidities, and accelerate postoperative protocols; however, a paucity exists for patient outcomes in the literature regarding tension-side-fixation. The purpose of this study is to report the outcomes for tension-side Lapidus fixation. A retrospective analysis was performed of 81 patients who underwent tension-side-fixation Lapidus. Data collection consisted of: time to weight-bear, time to return to regular shoegear, hardware removal rate, revision rate, recurrence rate, relative metatarsal shortening, and nonunion rates. Mean patient age was 44 years old (range: 16-82). There were 65 females, and 16 males. The average time to weightbearing was 10.4 days. Time to return to regular shoegear was a mean of 6 weeks (ranging 2-10 weeks). Hardware removal rate was 1.2%. The recurrence rate was 8.6% (7 of 81 patients) and 5 of those 7 patients experienced recurrence before frontal-plane-correction was adopted by the surgeon. The revision rate was 0% and despite 8.6% recurrence, no patients were dissatisfied or requested a revisional procedure. The first-metatarsal shortening was a mean of 0.42 mm. The complications were as follows: 7% superficial dehiscence, 1.2% superficial wound infection, 0% deep infection, and 1.2% asymptomatic nonunion. This study suggests tension-side-fixation for Lapidus arthrodesis may allow for safe early return to weightbearing, early return to regular shoegear, low hardware removal rate, low revision rate, low metatarsal shortening, and low nonunion rate.

Open vs Minimally Invasive Resection of the First Metatarsocuneiform Joint: An Anatomical Study

BACKGROUND

The modified Lapidus arthrodesis is a standard procedure to correct middle to severe hallux valgus (HV) deformities. Recently, minimally invasive techniques of first metatarsocuneiform joint (MCJ) resection using a Shannon burr were described. The primary goal of this study is to compare the anatomical efficacy and safety of first MCJ resection using a straight 2 × 13-mm Shannon burr and minimally invasive technique (MIS) vs an open technique using an oscillating saw.

METHODS

Ten pairs of fresh frozen cadaveric feet were randomly assigned to open or MIS first MCJ resection with subsequent systematic dissection. For the MIS procedure, a dorsomedial approach was used and for the open procedure a medioplantar approach was used. Cartilage removal was investigated by analyzing standardized scaled photographs of the resected articular surfaces with ImageJ software. Nearby structures at risk were analyzed for iatrogenic violation: tibialis anterior (TA), extensor hallucis longus (EHL) and peroneus longus (PL) tendons, and the Lisfranc ligament complex (LLC).

RESULTS

In the MIS group, the median cartilage resection was 85.9% at the cuneiform and 85.6% at the metatarsal bone compared to 100% cartilage resection in open technique (P < .01). Iatrogenic damage of the LLC, EHL, and TA tendons was not found in any group. The PL tendon was thinned out (<25% of tendon thickness) in 4 cases (40%) in the open group and in 1 case (10%) in the MIS group. A safe zone of 3.0 mm between the articular surface of the cuneiform bone and the LLC was identified, which can be resected without putting the LLC at risk when performing lateral-based wedge resections.

CONCLUSION

In this cadaver study with the procedures performed by an experienced foot and ankle surgeon, and using 2 different surgical approaches, we found general parity between the Shannon burr MIS technique vs oscillating saw open technique techniques with more risk to the PL with our open technique and approximately 15% less cartilage resection with our MIS technique.

LEVEL OF EVIDENCE

Level V, cadaver study.

Radial versus dorsal plating for trapeziometacarpal arthrodesis: a comparative biomechanical study

Trapeziometacarpal arthrodesis is used for the treatment of advanced arthritis. Insufficient stabilization of the joint may lead to nonunion or hardware problems after arthrodesis. The purpose of this study was to compare the biomechanical properties of dorsal versus radial plate fixation of the trapeziometacarpal joint in ten pairs of fresh-frozen cadaveric hands. The biomechanical performance of each group was measured for stiffness in extension and flexion and load to failure using cantilever bending tests. The stiffness in extension was lower in the dorsally positioned group than in the radially positioned group (12.1 versus 15.2 N/mm, respectively). Load to failure was comparable between both groups (53.9 versus 50.9 N, respectively). A radially positioned locking plate for trapeziometacarpal arthrodesis may be biomechanically advantageous.

Biomechanical Comparison of Medio-Plantar and Plantar Plate Fixation for First Tarsometatarsal Joint Arthrodesis

Plantar plate positioning has been demonstrated as biomechanically superior. However, some operators remain resentful about the morbidity of the surgical approach. To provide improved plate fixation for first tarsometatarsal joint arthrodesis with respect to the tibialis anterior tendon, a medio-plantar plate was developed. The purpose of this biomechanical study was to compare its construct stability to that of a plantar plate construct. Twelve pairs of fresh frozen human specimens were used in a matched pair test. Each pair was fixed with a 4 mm compression screw and either a plantar locking plate or a medio-plantar locking plate. A cantilever beam test was performed in dorsiflexion. Before and after cyclic loading (5000 cycles; 40 N), bending stiffness and relative movements at the joint space were monitored in a quasi-static test including optical motion tracking. Maximum load and bending moment to failure were investigated in a load-to-failure ramp test. The bending stiffness of both groups did not significantly differ before (plantar 49.9 N/mm ± 19.2; medio-plantar 53.9 N/mm ± 25.4, p = 0.43) or after (plantar 24.4 N/mm ± 9.7; medio-plantar 35.3 N/mm ± 22.0, p = 0.08) cyclic loading but decreased significantly in both groups (p < 0.01) after cyclic loading. Relative movement increased significantly during cyclic testing in both groups (p < 0.01) but did not differ significantly between the groups before (p = 0.29) or after (p = 0.16) cyclic loading. Neither load nor bending moment to failure were significantly different (plantar 225 N ± 78, 10.8 Nm; medio-plantar 210 N ± 86, 10.1 Nm, p = 0.61). Both plate constructs provided equivalent construct stability, both being well suited for Lapidus arthrodesis.

Identifying Risk Factors for Nonunion of the Modified Lapidus Procedure for the Correction of Hallux Valgus

There is a paucity of literature characterizing risk factors for nonunion associated with the modified Lapidus procedure for correction of hallux valgus. The purpose of this study was to evaluate risk factors associated with nonunion for Lapidus bunionectomies. Patients who underwent modified Lapidus procedure from 2009 to 2018 were retrospectively reviewed. Patient's age, sex, body mass index, prior bunionectomy, history of tobacco use, presence of diabetes mellitus or hypothyroidism, and fixation method were recorded along with pre- and postoperative radiographic parameters. A multiple logistic regression analysis was implemented to estimate the odds of nonunion. Of the 222 patients who met inclusion criteria, nonunion with modified Lapidus procedure was observed in 20 patients (9.01%). Odds of nonunion with modified Lapidus procedure were greater for patients who had undergone previous bunionectomy (odds ratio [OR] = 3.957, 95% confidence interval [CI]: 1.021-15.338), as body mass index increased (OR = 1.091, 95% CI: 1.018-1.170), and as preoperative HV angle increased (OR = 1.108, 95% CI: 1.020-1.203). Odds of nonunion were lower for patients as preoperative intermetatarsal angle increased (OR = 0.739, 95% CI: 0.580-0.941). No significant increased odds of nonunion were found between fixation methods.

Salvage of Failed Lisfranc/Midfoot Injuries

Salvage of Lisfranc, or tarsometatarsal injuries, may be necessary because of a variety of clinical scenarios. Although rare, these injuries represent a broad spectrum of injury to the midfoot ranging from low-energy ligamentous injuries to high-energy injuries with significant displacement and associated fractures. Poor outcomes and complications may occur including posttraumatic arthritis, instability, pain, infection, and loss of function. Strategies and technical considerations for salvage of these complex injuries are provided.

Radiographic Outcomes, Union Rates, and Complications Associated With Plantar Implant Positioning for Midfoot Arthrodesis

Background:

Midfoot arthrodesis has long been successfully included in the treatment paradigm for a variety of pathologic foot conditions. A concern with midfoot arthrodesis is the rate of nonunion, which historically has been reported between 5% and 10%. Plantar plating has also been noted to be more biomechanically stable when compared to traditional dorsal plating in previous studies. Practical advantages of plantar plating include less dorsal skin irritation and the ability to correct flatfoot deformity from the same medial incision. The purpose of this study is to report the arthrodesis rate, the success of deformity correction, and the complications associated with plantar-based implant placement for arthrodesis of the medial column.

Methods:

A retrospective review was undertaken of all consecutive patients between 2012 and 2019 that underwent midfoot arthrodesis with plantar-positioned implants. Radiographic outcomes and complications are reported on 62 patients who underwent midfoot arthrodesis as part of a correction for hallux valgus deformity, flatfoot deformity, degenerative arthritis, Lisfranc injury, or Charcot neuroarthropathy correction.

Results:

Statistically significant improvement was seen in the lateral talus–first metatarsal angle (Meary angle) and medial arch sag angle for patients treated for flatfoot deformity correction. In patients treated for hallux valgus deformity, there was a reduction in the intermetatarsal angle from 15.4 to 6.8 degrees. The overall nonunion rate was 6.45% in all patients. The rate of nonunion was higher at the NC joint compared to the TMT joint and with compression claw plates. One symptomatic nonunion required revision surgery (1.7%). There were no nonunions when excluding neuroarthropathy patients and smokers. The odds ratio (OR) for nonunion in patients with neuroarthropathy was 6.05 ( P < .05), and in active smokers the OR was 2.33 ( P < .05).

Conclusion:

Plates placed on the plantar bone surface for midfoot arthrodesis achieved and maintained deformity correction with rare instances of symptomatic hardware for a variety of orthopedic conditions. An overall clinical and radiographic union rate of 94% was achieved. The radiographic union rate improved to 100% when excluding both neuroarthropathy patients and smokers. The incidence of nonunion was higher in smokers, neuroarthropathy patients, naviculocuneiform joint fusions, use of compression claw plates, and when attempting to fuse multiple joints. Incisional healing complications were rarely seen other than in active smokers.

Level of Evidence:

Level IV, case series.

Locked Dorsal Compression Plate Arthrodesis for Degenerative Arthritis of the Midfoot

Midfoot arthrodesis is the accepted surgical treatment for symptomatic midfoot arthritis. The published literature has focused on joint-spanning static fixation. Several companies have developed diamond-shaped locked dorsal compression plates, which allow for longitudinal joint compression. After dorsal plate insertion, a spreader device opens the arms of the plate mediolaterally, which allows the plate to compress longitudinally. This work describes outcomes of such locked dorsal compression plates for midfoot arthritis at a single institution. We reviewed 62 patients who underwent midfoot arthrodesis for symptomatic midfoot arthritis using locked dorsal compression plates over a 7-year period. A total of 173 joints were spanned for fusion. The primary outcome measure was radiographic union and visual analog scale pain scores. Characteristics of patients who experienced nonunion versus those who had union were evaluated. Of the 173 joints, there was a 81.5% fusion rate (141/173 joints) and 14 patients experienced nonunion. There was a statistically significant difference in the average number of joints spanned in patients with nonunion (3.6) and patients with union (2.5) (p = .02). Locked dorsal compression plate arthrodesis is a viable technique for achieving midfoot fusion. This mechanical method of compression does not, however, lend itself to improved fusion rates compared with prior reports. A greater number of arthrodesis sites is associated with a higher nonunion rate. Emerging technology using newer materials and improved biomechanical designs may show improved results.

3D digital image correlation evaluation of arthrodesis implants

BACKGROUND

Hallux valgus is a pathological condition that is typically treated via the Lapidus procedure. The purpose of this study was to understand the biomechanical characteristics of bone, implant devices and the bone-implant interface.

METHODS

In-situ digital image correlation was performed on polyurethane foam, a known bone substitute in a modified three-point bend test frame. We introduced this modified rig as an enhanced methodology for characterizing bone and implant device mechanical performance. This new methodology was validated using aluminum rod specimens, in three and four-point bend setups followed by new configurations to reveal implications of load configurations on joint displacement and implant performance. Bone substitute specimens were constructed with nitinol staples or locking plate to minimize gapping at the 1^st tarsometatarsal during testing.

FINDINGS

Bone-implant interface characterization was enabled by digital image correlation, identifying maximum strain concentrations of 1.5% along the interfaces. Interfacial characteristics were analyzed in context with gap displacement allowed by the implant over cyclical loading. The locking plate implant and nitinol staples gapped an average of 2.2 mm and 3.2 mm respectively under 50 Newtons. Removing all load, the locking plate implant and nitinol staples averaged ~0.8 mm and ~0.3 mm of residual gapping respectively.

INTERPRETATION

Our results demonstrate that locking plates provide more initial stability and resistance against gapping under load but are unable to recover compression throughout repetitive loading as seen with the nitinol staple technology. This could lead to a paradigm shift in materials used for early weight bearing protocols post-operation.