Mechanical comparison of biplanar proximal closing wedge osteotomy with plantar plate fixation versus crescentic osteotomy with screw fixation for the correction of metatarsus primus varus

Biomechanical consequences of proximal screw placement in minimally invasive surgery for hallux valgus correction

Hallux valgus is one of the most common surgically corrected forefoot deformities. Studies evaluating clinical outcomes of minimally invasive chevron and akin (MICA) procedure have shown shorter operation time, faster recovery, and smaller scars compared to the open approach. Previous biomechanical cadaveric studies have largely focused on the open approach with minimal on MICA. To our knowledge, no studies have compared different proximal screw placements in MICA which can either be three-point fixation or intramedullary. This study aims to compare the biomechanical properties of fixation between these two techniques in MICA. Six matched pairs of human fresh frozen cadaveric feet were randomized to either three-point fixation or intramedullary groups. Both procedures were performed by a single fellowship-trained orthopaedic foot and ankle surgeon. Using a material testing machine, each specimen underwent 1000 cycles of plantar-to-dorsal uniaxial loads from 0 to 31 N in cantilever configuration while monitoring bending stiffness and distal fragment dorsal angulation. They were then subjected to load until failure at a compression rate of 10 mm/min. Specimens from both groups tolerated the walking fatigue test. Mean bending stiffness of three-point fixation was 84% higher than intramedullary constructs (P=0.002). Mean dorsal angulation of intramedullary was thrice that of three-point fixation constructs (P=0.008). Mean load to failure of three-point fixation was 30% higher than intramedullary constructs (P=0.001). Three-point fixation provide superior biomechanical stability compared to intramedullary proximal screw placement. The surgical technique using three-point proximal screw fixation can offer robust fixation and lead to better clinical outcomes. LEVEL OF CLINICAL EVIDENCE: 5.

An Approach to Managing Midfoot Charcot Deformities

We present an approach to managing complex deformities in Charcot neuroarthropathy that typically present around the midfoot. This approach follows a stepwise progression from prevention, early detection, nonoperative through to operative management. It centers on multidisciplinary care with input from diabetologists, orthotists, plaster technicians, physiotherapists, orthopedic, vascular, and/or plastic surgeons. We discuss the timing of surgery with regard to Eichenholtz stage of disease and trends toward early surgical intervention. We review traditional and new surgical concepts. We evaluate the role of limited interventions. We aim to provide a template for deciding where future research priorities should be directed.

Range of Motion of the First Metatarsophalangeal Joint After Different Capsulorrhaphies: A Comparative Cadaver Study

BACKGROUND

Capsulorrhaphy restricts the motion of the first metatarsophalangeal joint (MTPJ) in hallux valgus surgery. However, changes in motion of the first MTPJ immediately after surgery that resulted from different capsulorrhaphy methods have not been compared. The primary aim of this study was to compare the immediate effect of Y-shaped and inverted L capsulorrhaphy methods on the range of motion (ROM) of the first MTPJ.

METHODS

Y-shaped and inverted L capsulorrhaphies were performed on 16 human cadaveric feet. Passive dorsiflexion and plantarflexion of the first MTPJ were then compared preoperatively and postoperatively.

RESULTS

In this cadaveric study, the inverted L capsulorrhaphy method led to a ROM loss in the first MTPJ; the joint stiffness from the Y-shaped capsulorrhaphy is significantly less than that from the inverted L capsulorrhaphy.

CONCLUSIONS

The inverted L capsulorrhaphy may lead to a ROM loss in the first MTPJ immediately after surgery. We recommend that surgeons close the capsule of the first MTPJ with a Y-shaped capsulorrhaphy, which is less likely to result in a ROM loss in the first MTPJ in the early postoperative period.

Rigid Internal Fixation of Proximal Crescentic Metatarsal Osteotomy in Hallux Valgus Correction

BACKGROUND

The purpose of this study was to evaluate outcomes utilizing a low-profile titanium plate and screw construct for rigid fixation of first ray proximal crescentic osteotomies in the treatment of hallux valgus.

METHODS

Forty-eight patients (53 feet) with mild to severe hallux valgus were prospectively enrolled and completed 12-month follow-up. All were treated with a proximal crescentic osteotomy, fixed with a low-profile titanium plate, distal soft tissue correction, with or without an Akin osteotomy. Recorded outcomes included change in first ray dorsiflexion angles, need for hardware removal, radiographic and clinical evaluation, pain, and American Orthopaedic Foot & Ankle Society (AOFAS) scores.

RESULTS

All patients achieved radiographic union of their osteotomy. An Akin osteotomy was performed in 83% of patients. Seventeen feet (32%) had hardware removed. First ray dorsiflexion angles increased from a mean of 1.6 degrees preoperatively to 5.0 degrees postoperatively (P < .001). Dorsal malunion, defined as change in dorsiflexion angle greater than 1 standard deviation above the mean, occurred in 7 feet. The mean hallux valgus angle improved from 29 to 9 degrees (P < .001). The mean 1-2 intermetatarsal angle decreased from 14 to 6 degrees (P < .001). The first metatarsophalangeal joint range of motion decreased from 77 to 59 degrees (P < .001). The mean visual analog scale score improved from 4 to 0.7 (P < .0001). The mean AOFAS score improved from 55 to 89 points (P < .001).

CONCLUSION

Proximal crescentic metatarsal osteotomy, fixed with a low-profile titanium plate and screw construct, with distal soft tissue repair, and Akin osteotomy as indicated, was a safe and reliable method for operative treatment of hallux valgus.

LEVEL OF EVIDENCE

Level IV, retrospective case series.

Proximal oblique metatarsal osteotomy for hallux valgus using a plantar locking plate

BACKGROUND

The purpose of this retrospective study was to evaluate the clinical and radiological results of hallux valgus surgery using a plantar locking plate.

METHODS

Proximal oblique metatarsal osteotomy combined with distal soft tissue treatment was performed in 59 adult patients (68 feet) with hallux valgus, using an anatomically pre-contoured plantar locking plate for fixation of the osteotomy. The median age was 64.0 years and the median follow-up period was 16.5 months.

RESULTS

The mean JSSF scale improved significantly from 56.0 points preoperatively to 95.8 points postoperatively. The mean intermetatarsal angle and hallux valgus angle decreased from 16.4° and 41.8° preoperatively to 4.2° and 10.8° postoperatively, respectively. The mean inclination angle was 19.9° preoperatively and 20.5° postoperatively. Removal of hardware was needed in 2 feet (2.9%).

CONCLUSIONS

Proximal oblique metatarsal osteotomy is an effective method for relief of pain and improvement of function in correction of hallux valgus deformity. Use of a plantar locking plate provides sufficient maintenance of the correction, and complications associated with the hardware are rare.

Plate Alone Versus Plate and Lag Screw for Lapidus Arthrodesis: A Biomechanical Comparison of Compression

Background. Arthrodesis of the first tarsal metatarsal joint can be accomplished in many ways. The compressive force attained between various constructs remains unclear. This study compares compression achieved through a locking/compression Lapidus plate both with and without the addition of a lag screw. Methods: A dorsal medial Lapidus/locking compression plate (Total Compression Plate System, OrthoPro, Salt Lake City, UT, now Wright Medical) was applied to one cadaveric limb, while the same plate with the addition of a 4.0-mm cannulated lag screw was applied to the contralateral limb for a total of 5 matched pairs of cadaveric specimens. Compressive force was recorded over time and compared between the constructs using a compression sensor (8" FlexiForce Resistive Force Sensor, Phidgets Inc, Calgary, Alberta, Canada). Results: Compression was maintained for 45.4 minutes in the plate only construct, and 317 minutes with the addition of the lag screw (P = .010). The mean time to 50% peak compression for the plate only construct was 4.90 minutes compared with 15.11 minutes for plate with lag screw construct (P = .012). Conclusion: The addition of a lag screw is recommended for extending the length of compression and possibly reducing nonweightbearing time and the risk of nonunion. Levels of Evidence: Level V.

A new "tension side" locking plate for Hallux Valgus: A prospective multicentre case series

BACKGROUND

Proximal osteotomy of the first metatarsal is often indicated for Hallux Valgus correction. Previously recognised complications however, include transfer metatarsalgia, first metatarsophalangeal joint stiffness, problems with fixation and prominence of metalware.

METHODS

We report on one year follow up of an international prospective series between June 2009 and October 2012 involving three centres, including 91 feet (58 patients) that underwent proximal osteotomy, using a new locking plate applied to the plantar surface of the metatarsal.

RESULTS

Mean Hallux Valgus angle improved from 27.9 (±13.1)° to 12.4 (±8.2)° while mean Intermetatarsal angle improved from 12.5 (±8.4) to 7.1 (±3.4) and there was a statistically significant improvement in both mean AOFAS-HMI score 54.2 (±13.9) to 94.0 (±9.5) and Visual Analogue Pain Scale 4.7 (±1.5) to 0.6 (±1.3). 70% of patients were back at their preoperative employment at five weeks. Mean surgical time was 56min and the plate was generally well tolerated. There were five implant related complications.

CONCLUSIONS

Locked fixation from the tension side of the construct encourages early weight bearing with a low risk of implant prominence. Our radiological, functional and clinical parameters are comparable with similar series and we therefore recommend this technique.

Fixation of the Proximal Metatarsal Crescentic Osteotomy Using a Head Locking X-Plate

BACKGROUND

We present a new method to stabilize proximal crescentic osteotomies (PCOs) for the correction of moderate to severe hallux valgus.

METHODS

A single-center prospective study with a consecutive series of 72 patients (94 feet) with a PCO was performed using a head locking X-plate. The primary aim was to investigate the stability of the osteotomy, measuring the dorsal elevation of the first metatarsal head, first cuneiform height, talus-first metatarsal angle, and first metatarsal inclination pre- and postoperatively. A secondary outcome assessed weight distribution during gait, quality of life, and radiologically documented bone healing process.

RESULTS

Ninety-three percent of the feet were within ±2 mm change for dorsal elevation of the first metatarsal head, and 72% for the medial cuneiform height. Eighty-nine percent were within ±4 degrees change for the first metatarsal inclination, 73% for the talus-first metatarsal angle, and 100% for the calcaneus pitch angle. The mean changes between pre- and 1-year postoperative were not significantly different for any of the stability measurements except for the first metatarsal inclination angle. The SF36 showed a significant improvement of physical function, general health, and decreased bodily pain. Harris mat footprints showed a decrease of 46% underneath the second and a pressure decrease of 40% underneath the third metatarsal head.

CONCLUSION

This technique, of using a head locking X-plate to stabilize the PCO, showed satisfactory and reproducible results in terms of stability, clinical outcome, bone healing, and patient satisfaction. The plate provided substantial support for the PCO resulting in adequate and easy fixation.

LEVEL OF EVIDENCE

Level IV, retrospective case series.

First metatarsal proximal opening wedge osteotomy for correction of hallux valgus deformity: comparison of straight versus oblique osteotomy

PURPOSE

The aim of this study was to compare clinical and radiographic outcomes of proximal opening wedge osteotomy using a straight versus oblique osteotomy.

MATERIALS AND METHODS

We retrospectively reviewed 104 consecutive first metatarsal proximal opening wedge osteotomies performed in 95 patients with hallux valgus deformity. Twenty-six feet were treated using straight metatarsal osteotomy (group A), whereas 78 feet were treated using oblique metatarsal osteotomy (group B). The hallux valgus angle (HVA), intermetatarsal angle (IMA), distal metatarsal articular angle, and distance from the first to the second metatarsal (distance) were measured for radiographic evaluation, whereas the American Orthopaedic Foot and Ankle Society (AOFAS) forefoot score was used for clinical evaluation.

RESULTS

Significant corrections in the HVA, IMA, and distance from the first to the second metatarsal were obtained in both groups at the last follow-up (p<0.001). There was no difference in the mean IMA correction between the 2 groups (6.1±2.7° in group A and 6.0±2.1° in group B). However, a greater correction in the HVA and distance from the first to the second metatarsal were found in group B (HVA, 13.2±8.2°; distance, 25.1±0.2 mm) compared to group A (HVA, 20.9±7.7°; distance, 28.1±0.3 mm; p<0.001). AOFAS scores were improved in both groups. However, group B demonstrated a greater improvement relative to group A (p=0.005).

CONCLUSION

Compared with a straight first metatarsal osteotomy, an oblique first metatarsal osteotomy yielded better clinical and radiological outcomes.

Intraosseous fixation compared to plantar plate fixation for first metatarsocuneiform arthrodesis: a cadaveric biomechanical analysis

BACKGROUND

Metatarsocuneiform (MTC) fusion is a treatment option for management of hallux valgus. We compared the biomechanical characteristics of an internal fixation device with plantar plate fixation.

METHODS

Seven matched pairs of feet from human cadavers were used to compare the intramedullary (IM) device plus compression screw to plantar plate combined with a compression screw. Specimen constructs were loaded in a cyclic 4-point bending test. We obtained initial/final stiffness, maximum load, and number of cycles to failure. Bone mineral density was measured with peripheral quantitative computed tomography. Performance was compared using time to event analysis with number of cycles as time variable, and a proportional hazard model including shared frailty model fitted with treatment and bone mineral density as covariates.

RESULTS

On average the plates failed after 7517 cycles and a maximum load of 167 N, while the IM-implants failed on average after 2946 cycles and a maximum load of 69 N. In all pairs the 1 treated with IM-implant failed earlier than the 1 treated with a plate (hazard ratio for IM-implant versus plate was 79.9 (95% confidence interval [6.1, 1052.2], P = .0009). The initial stiffness was 131 N/mm for the plantar plate and 43.3 N/mm for the IM implant. Initial stiffness (r = .955) and final stiffness (r = .952) were strongly related to the number of cycles to failure. Bone mineral density had no effect on the number of cycles to failure.

CONCLUSION

Plantar plate fixation created a stronger and stiffer construct than IM fixation.

CLINICAL RELEVANCE

A stiffer construct can reduce the risk of nonunion and shorten the period of non-weight-bearing.

Mechanical comparison of cortical screw fixation versus locking plate fixation in first metatarsal base osteotomy

The oblique closing base wedge osteotomy has been used for surgical treatment of moderate to severe hallux valgus deformities with an intermetatarsal angle typically greater than 15°. Several postoperative complications have been identified that relate to failure of the fixation construct used to fixate the osteotomy, especially when that construct has been subjected to a vertical load. We performed a mechanical analysis comparing 2 constructs used to fixate oblique osteotomies of the first metatarsal using composite first metatarsals. An oblique base osteotomy was uniformly performed on 40 composite first metatarsals. Of the 40 specimens, 20 were fixated with a locking plate construct and 18 with a cortical screw construct, consisting of an anchor and compression screw (2 specimens from the latter group were excluded because of hinge fracture). Each specimen was loaded in a materials testing machine to measure the maximum load at construct failure when a vertical force was applied to the plantar aspect of the metatarsal head. The mean load to failure for the locking plate construct was significantly greater than the cortical screw construct (190.0 ± 70 N versus 110.3 ± 20.3 N, p < .001). Our study results have demonstrated that the locking plate construct was able to withstand a significantly greater vertical load before failure than was the 2-cortical screw construct in oblique osteotomies performed at the base of composite first metatarsals.

Fixation of the Lapidus arthrodesis with a plantar interfragmentary screw and medial low profile locking plate

The Lapidus arthrodesis can be used to correct pathology within the forefoot or midfoot, and severe hallux valgus deformities as well as hypermobility of the medial column may be amenable to correction with this procedure. Many different skeletal fixation methods have been described for this procedure, and one form that appears to provide enough construct stability to allow patients to bear weight early in the postoperative period is described herein. This construct consists of an interfragmental compression screw oriented from the plantar aspect of the first metatarsal to the superior aspect of the medial cuneiform, with medial locking plate augmentation.

Biomechanical in vitro - stability testing on human specimens of a locking plate system against conventional screw fixation of a proximal first metatarsal lateral displacement osteotomy

INTRODUCTION

The aim of this study was to examine resistance to angulation and displacement of the internal fixation of a proximal first metatarsal lateral displacement osteotomy, using a locking plate system compared with a conventional crossed screw fixation.

MATERIALS AND METHODOLOGY

Seven anatomical human specimens were tested. Each specimen was tested with a locking screw plate as well as a crossed cancellous srew fixation. The statistical analysis was performed by the Friedman test. The level of significance was p = 0.05.

RESULTS

We found larger stability about all three axes of movement analyzed for the PLATE than the crossed screws osteosynthesis (CSO). The Friedman test showed statistical significance at a level of p = 0.05 for all groups and both translational and rotational movements.

CONCLUSION

The results of our study confirm that the fixation of the lateral proximal first metatarsal displacement osteotomy with a locking plate fixation is a technically simple procedure of superior stability.

First metatarsal length change after basilar closing wedge osteotomy for hallux valgus

BACKGROUND

Hallux valgus deformities with large intermetatarsal angles require a more proximal metatarsal procedure to adequately correct the deformity. Due to the relative ease of a closing wedge osteotomy, this technique was adopted but with concern over first metatarsal shortening. In this study, we primarily evaluated angular correction and first metatarsal shortening.

MATERIALS AND METHODS

We evaluated 70 feet in 57 patients (average age, 54 years) with 52 female and five male. The average followup was 14 (range, 6 to 45) months. The charts were reviewed for the presence of metatarsalgia. Digital radiographic measurements were made for pre- and postoperative hallux valgus and intermetatarsal angles, dorsiflexion angle of the first metatarsal, and absolute and relative shortening of the first metatarsal.

RESULTS

The average hallux valgus angle improved from 31 to 11 degrees (p < 0.0001) and intermetatarsal angle from 13.2 to 4.4 angles (p < 0.0001). The absolute shortening of the first metatarsal was 2.2 mm and relative shortening was 0.6 mm. There was 1.3 degrees of dorsiflexion on average.

CONCLUSION

Excellent correction of the deformity with minimal dorsiflexion or new complaints of metatarsalgia was found with this technique. The new method of assessing the relative shortening found to be less than the absolute shortening, which we feel more accurately reflects the functional length of the first metatarsal.

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.

Comparison of the proximal chevron and Ludloff osteotomies for the correction of hallux valgus

BACKGROUND

Although several studies have described good results of proximal chevron and Ludloff osteotomies, there have been no studies comparing the results of these two techniques at a single institution.

MATERIALS AND METHODS

We consecutively evaluated 46 patients who underwent proximal chevron osteotomies and 52 patients who underwent Ludloff osteotomies. Patients were evaluated by preoperative and postoperative weight bearing radiographs and the American Orthopaedic Foot and Ankle Society (AOFAS) hallux MP score.

RESULTS

Both groups had similarly high AOFAS scores and good correction by radiographic parameters. No statistically significant differences were found with respect to correction of hallux valgus angle (HVA) and intermetatarsal angle (IMA) between the two groups. Significant shortening of the first metatarsal was found after Ludloff osteotomy (p < 0.05). At 6 weeks after surgery, the pain subscore was significantly lower in the proximal chevron group than in the Ludloff group (p < 0.05).

CONCLUSIONS

The proximal chevron and Ludloff osteotomies yielded equivalent clinical and radiological results. The Ludloff osteotomy with lag screw fixation is more stable and does not require postoperative hardware removal, although it is technically demanding and has a tendency toward greater shortening of the first metatarsal.

Results of lapidus arthrodesis and locked plating with early weight bearing

In the endeavor toward Lapidus fusion, the authors have studied a new application of locked plating for the first tarsometatarsal joint. The goal was to assess the time to fusion, time to ambulation, rate of delayed union/nonunion, rate of revision, and need for hardware removal following the use of locked-plate technology in the fusion of the first tarsometatarsal joint. The findings denoted an average of 6.95 weeks to radiographic fusion, an average of 2 weeks to ambulation, a 9.52% rate of asymptomatic mal-union, a 0% rate of delayed union or nonunion, and a 0% rate of revision. The rate of need for hardware removal was 4.76%.

Superconstructs in the treatment of charcot foot deformity: plantar plating, locked plating, and axial screw fixation

Management of Charcot's deformity of the foot and ankle continues to challenge physicians. Medical co-morbidity, peripheral neuropathy, vascular disease, and immune impairment cause severe problems for these patients and, when combined with neuroarthropathy, can lead to amputation. Progressive bony deformity and bone resorption, which may accompany neuroarthropathy, only increase the challenge of surgical treatment. These challenges have led physicians to develop "superconstruct" techniques to improve fixation, whereby fusion is extended beyond the zone of injury to include joints that are not affected, bone resection is performed to shorten the extremity to allow for adequate reduction of deformity without undue tension on the soft tissue envelope, the strongest device is used that can be tolerated by the soft tissue envelope; and the devices are applied in a novel position that maximizes mechanical function. This article reviews three techniques designed to achieve lasting deformity correction and successful arthrodesis: plantar plating, locked plating, and axial screw fixation.

Screw versus plate fixation of proximal first metatarsal crescentic osteotomy

BACKGROUND

Hallux valgus associated with metatarus primus varus is a deformity that disrupts normal foot function. Standard treatment has often included distal or proximal metatarsal osteotomy with or without a distal soft tissue procedure. The intrinsically unstable proximal crescentic osteotomy relies on operative fixation for stability. This study examined the strength of fixation of a single screw versus a plate for stabilization of proximal first metatarsal crescentic osteotomies for correction of hallux valgus.

MATERIALS AND METHODS

A crescentic osteotomy was performed on nine pairs of fresh/frozen cadaveric feet. The distal fragment was rotated laterally and the osteotomy was temporarily stabilized with a Kirschner wire. The osteotomized metatarsal fragments were fixed with a cancellous screw on one side and single plate on the contralateral side. Each specimen was loaded in a mechanical testing machine, and its response was measured by monitoring the opening of the osteotomy and change in alignment of the fragments. Position and alignment of the proximal and distal fragments were calculated.

RESULTS

All of the measures of fixation strength were statistically greater in specimens treated with a plate rather than with screw fixation. Plate fixation provided approximately twice the resistance to disruption of the osteotomy under cyclic loading conditions.

CONCLUSION

The dorsal plate is biomechanically more stable than a single cancellous screw when applied to proximal crescentic osteotomies.

CLINICAL RELEVANCE

The greater stability of the plate construct may be helpful in selecting the fixation device for these osteotomies.

Arthrodesis of the first metatarsocuneiform joint: a comparative cadaveric study of external and internal fixation

Arthrodesis of the first metatarsocuneiform joint for the treatment of severe hallux abductovalgus with or without hypermobility of the first ray has gained popularity in recent years. The purpose of the current study was to compare the strength of external fixation to internal fixation for arthrodesis of the first metatarsocuneiform joint in a cadaveric model. Ten pairs of fresh frozen lower extremity cadaver specimens were used, and randomly assigned to fixation at the first metatarsocuneiform joint with crossed cannulated screws or a monorail uniplanar external fixator. Test specimens were then loaded to failure, which was defined as 3 mm or more of displacement at the arthrodesis site. Because of complications encountered during testing, 4 pairs of specimens were excluded from the final results. In the remaining 12 specimens (6 pairs of cadaver limbs), the mean maximal load to failure was 2300.02 +/- 711.86 N for the external fixator and 1666.38 +/- 1072.75 N for the internal fixation construct, and although this difference was not statistically significant (P = .2557), it was likely to have been clinically significant since approximately 27.55% more force was required to disrupt the external fixation construct in comparison with the internal fixation construct. Given these findings, further research into the mechanical and clinical properties of internal and external fixation for first metatarsocuneiform joint arthrodesis is warranted.

LEVEL OF CLINICAL EVIDENCE

5.

Crossed screws versus dorsomedial locking plate with compression screw for first metatarsocuneiform arthrodesis: a cadaver study

BACKGROUND

We hypothesized that a dorsomedial locking plate with adjunct screw compression would provide superior rigidity compared to crossed screws for first metatarsocuneiform (MTC) arthrodesis.

MATERIALS AND METHODS

In ten matched lower extremity pairs, specimens in each pair were randomly assigned to receive screw fixation or plate with screw fixation. Bone mineral density (BMD) was measured. For the crossed-screw construct, two 4.0-mm cannulated screws were used. One screw was inserted dorsal to plantar beginning from the first metatarsal 10 to 15 mm distal to the joint, and the second was inserted from the cuneiform 8 to10 mm proximal to the joint, medial to the first screw, into the first metatarsal. For the plate construct, a 4.0-mm cannulated compression screw was inserted from the dorsal cortex of the first metatarsal to the plantar aspect of the medial cuneiform. A locking plate was inserted dorsomedially across the MTC joint. Specimens were loaded in four-point bend configuration (displacement rate, 5 mm/min) until failure of the fixation or 3-mm deformation. An extensometer was used to measure deformation.

RESULTS

There was no difference in load to failure or stiffness between the two groups. BMD was positively correlated with load to failure in the screw (r = 0.893, p = 0.001) and the plate (r = 0.858, p = 0.001) construct.

CONCLUSION

The plate construct with compression screw did not show different rigidity as compared with the screw construct with the numbers available.

CLINICAL RELEVANCE

Further investigation of a dorsomedial plate with adjunct screw compression may be warranted for first MTC arthrodesis.

Plate fixation for crescentic metatarsal osteotomy in the treatment of hallux valgus: an eight-year followup study

BACKGROUND

Distal soft tissue realignment and crescentic metatarsal osteotomy is a popular procedure in the treatment of hallux valgus. The traditional technique of screw fixation for crescentic osteotomy is technically demanding, and the inferior stability of this construct has been described. We evaluated the long-term results of a modified fixation method.

METHODS

Twenty-six patients (32 feet) undergoing this procedure were retrospectively reviewed. Five patients (six feet) were lost to followup. Mean age of the patients was 47 (14 to 74) years. The osteotomy was fixed with a 2.7 mm AO plate. Assessment of clinical and radiographic results was performed at a mean followup of 2.7 (1.3 to 7.2) years and 8.0 (6.1 to 12.0) years, respectively.

RESULTS

The mean American Orthopaedic Foot and Ankle Society (AOFAS) score improved from 57.9 to 90.5 at 2.7 years of mean followup, whereas the patient satisfaction rate was 96%. The intermetatarsal angle (IMA) and hallux valgus angle (HVA) improved from the mean preoperative values of 16.1 degrees and 34.2 degrees to 9.5 degrees and 16.3 degrees. At eight years of mean followup, the mean AOFAS score and patient satisfaction rate remained at 88.5% and 92%. The mean IMA and mean HVA were 9.7 degrees and 17.0 degrees. Complications included one case of hallux varus (4%) and two cases of recurrence (8%). The osteotomy achieved union in all cases.

CONCLUSIONS

Dorsal plate fixation of crescentic metatarsal osteotomy is a technically easier procedure. Equally good results can be achieved when compared with screw fixation methods, and the results can be maintained long-term.

Bunion surgery using locking-plate fixation of proximal metatarsal chevron osteotomies

BACKGROUND

Symptomatic large hallux valgus deformities commonly require surgical intervention with a proximal metatarsal osteotomy. A number of fixation methods have been described for proximal chevron osteotomies; one of the most recent is locking plates.

METHODS

We retrospectively reviewed the records of 16 consecutive patients (20 feet) with severe bunion deformities who had locking-plate fixation of proximal chevron osteotomies. Clinical evaluation focused on osteotomy healing, transfer lesions, and hardware-related complications. Preoperative and postoperative radiographic evaluation included the hallux valgus angle (HVA), 1-2 intermetatarsal angle (IMA), medial 1-2 intermetatarsal distance (MIMD; the amount of narrowing of the foot), sesamoid position, first metatarsal elevation, and metatarsal length change. A postoperative American Orthopaedic Foot and Ankle Society (AOFAS) score was obtained in all patients.

RESULTS

The average radiographic improvements were HVA, 16.0 degrees, IMA, 7.6 degrees, and MIMD, 9.0 mm. Sesamoid position improved in 16 of 20 feet. First metatarsal elevation averaged 0.8 degrees, and the average metatarsal shortening was less than 1 mm. The AOFAS score averaged 94.1 points. Two complications were unrelated to plate fixation.

CONCLUSIONS

The locking plate held alignment and position of the first ray after chevron osteotomy without clinical evidence of transfer lesions or hardware-related symptoms. Locking plates may improve stability of the proximal metatarsal after a chevron osteotomy for correction of hallux valgus.

Screw fixation compared to H-locking plate fixation for first metatarsocuneiform arthrodesis: a biomechanical study

BACKGROUND

Several different techniques have been used for fixation of first metatarsocuneiform (MTC) joint arthrodesis, a standard treatment for arthritis, instability, and deformity of the MTC joint. Improved plating systems using locking designs are now available, but no studies have yet compared this construct with other methods. We compared load to failure with a locking plate design versus standard crossed-screw fixation.

METHODS

Ten matched pairs of fresh frozen cadaver feet were used. The bone density of each pair was measured with DEXA scanning. One foot of each pair was randomly assigned to have a dorsomedial Normed H titanium locking plate (Normed Medizin-Technik Vertriebs-GmbH, D-78501 Tuttlingen, Germany) applied to the first MTC joint. On the other foot of the pair, fixation of the first MTC joint was done with crossed ACE DePuy 4.0 (DePuy/Ace, Warsaw, IN) titanium cannulated screws. The first metatarsal and first cuneiform were then isolated and planted in an epoxy resin. The specimens were loaded to failure in a four-point bending configuration using a MTS Mini Bionix test frame (MTS Systems Corp., Eden Prairie, MN). Failure was defined as displacement of more than 3 mm at the arthrodesis site. The Student t-test was used to determine any observed differences, with significance set at p <or= 0.05.

RESULTS

The mean maximal load to failure was 140.08 N (SD +/- 77.1) for screw fixation alone and 58.09 N (SD +/- 11.86) for the H-locking plate. This difference was statistically significant (p = 0.008). The mean stiffness of the construct for screw fixation alone was 83.10 N/mm (SD +/- 49.8) and 19.96 N/mm for the H-locking plate. This difference also was statistically significant (p = 0.004).

CONCLUSION

Screw fixation for first MTC arthrodesis created a stronger and stiffer construct than did the H-locking plate. This was likely due to the mechanical design of the implants. Compression across the MTC joint could be applied with the screws, but the plate relied on a fixed angle design with no compression.

Plantar-to-dorsal compared to dorsal-to-plantar screw fixation for proximal chevron osteotomy: a biomechanical analysis

BACKGROUND

A change in screw orientation in fixing the chevron proximal first metatarsal osteotomy was noted anecdotally to improve fixation strength. The authors hypothesized that plantar-to-dorsal screw orientation would be more stable than the conventional dorsal-to-plantar screw orientation for fixation of the chevron osteotomy. The purpose of this study was to determine if the load-to-failure and stiffness of the chevron type proximal first metatarsal osteotomy stabilized using plantar-to-dorsal screw fixation were greater than with the more conventional dorsal-to-plantar screw fixation method.

METHODS

One foot from each of eight matched cadaver pairs was randomly assigned to one of two groups: 1) fixation with a dorsal-to-plantar lag screw or 2) fixation with a plantar-to-dorsal lag screw. A proximal chevron osteotomy was then created using standard technique and the metatarsal was fixed according to previously established method. The bone was potted in polyester resin, and the construct was fitted into a materials testing system machine in which load was applied to the plantar aspect of the metatarsal until failure. The two groups were compared using a two-tailed Student t test.

RESULTS

The average load-to-failure and stiffness of the chevron osteotomy fixed with the plantar-to-dorsal lag screw were significantly greater (p < 0.05) than the group fixed with more conventional dorsal-to-plantar lag screws.

CONCLUSION

Plantar-to-dorsal screw orientation was more stable than the conventional dorsal-to-plantar screw orientation for fixation of the proximal chevron osteotomy. Plantar-to-dorsal screw orientation should be considered when using the chevron proximal first metatarsal osteotomy.

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.

First metatarsophalangeal joint motion after hallux valgus correction: a cadaver study

BACKGROUND

Surgical correction of hallux valgus deformities often results in decreased first metatarsophalangeal joint (MTPJ) range of motion. Loss of motion has been shown to affect patient satisfaction. The purpose of this study was to evaluate the immediate change in MTPJ range of motion that occurs after a distal soft-tissue reconstruction (DSTR) and proximal metatarsal osteotomy (PMO).

METHODS

DSTR and PMO were done on 16 below-knee cadaver specimens with clinically apparent hallux valgus deformities. Two examiners assessed preoperative and postoperative dorsiflexion (DF), plantarflexion (PF), and the total range of motion of the first MTPJ. The hallux valgus angle (HVA) and 1-2 intermetatarsal angle (1-2 IMA) were measured on simulated weightbearing radiographs before and after operative correction. Changes in motion were analyzed and correlated with the angular measurements.

RESULTS

The mean total range of motion preoperatively was 85.4 degrees (DF 70.5 degrees, PF 14.9 degrees) and significantly decreased (p < 0.005) 23.2 degrees to a postoperative value of 62.2 degrees (DF 47.9 degrees, PF 14.3 degrees). There was a significant (p < 0.005) decrease in DF (22.6 degrees) with the operative correction, but the loss of PF (0.6 degrees) was not significant (p = 0.7). There was no correlation between the magnitude of correction (HVA, 1-2 IMA) and the change in PF, DF, or total motion.

CONCLUSIONS

Correction of a hallux valgus deformity with a DSTR and PMO is associated with an immediate loss of range of motion that primarily affects the DF arc of the first MTPJ. The selective loss of DF may be related to a nonisometric capsular repair or tight intrinsic musculature, although there was no correlation with the magnitude of angular correction. The immediate decrease in motion observed in this cadaver study underscores the importance of early postoperative joint mobilization to prevent long-term stiffness after bunion surgery.

Mechanical comparison of two types of fixation for proximal first metatarsal crescentic osteotomy

BACKGROUND

The proximal crescentic osteotomy is an effective technique for correcting a widened 1-2 intermetatarsal angle associated with moderate to severe hallux valgus deformities. However, postoperative dorsal malunion at the osteotomy site from loss of fixation has been reported. The purpose of this study was to evaluate the biomechanical characteristics of a new custom-designed plate and compare it to the traditional screw and Kirschner wire construct.

METHODS

Twenty identical Sawbone (Pacific Research Laboratories, Vashon, WA) models were used for the study. A proximal crescentic osteotomy was done on each specimen, and 10 were secured with a dorsomedial plate (group I). The remaining 10 models were fixed with a screw and Kirschner wire combination (group II). Physiologic cyclical testing was done using a mechanical testing machine to evaluate dorsal displacement of the metatarsal. Load-to-failure testing was then done on each specimen to evaluate ultimate failure and stiffness of the constructs. Groups I and II were statistically compared using paired t-testing.

RESULTS

The mean dorsal displacement of the first metatarsal head after 1000 cycles was 0.19 mm (SD = 0.09 mm) for group I and 0.28 mm (SD = 0.15) for group II, and the difference was not statistically significant (p = 0.08). Group I demonstrated statistically superior ultimate failure strength (95.2 N) and stiffness (26.8 N/mm) compared to group II (73.7 N, 19.4 N/mm).

CONCLUSIONS

Based on Sawbone models, dorsal plate fixation of proximal crescentic osteotomy provides a stronger construct than the traditional screw and Kirschner wire construct. The clinical use of the specially-designed plate described in this study may lower the incidence of dorsal malunions that occur postoperatively and may decrease the occurrence of transfer metatarsalgia. Its application may be particularly helpful in patients with poor bone quality.

The first metatarsal bone under loading conditions: a finite element analysis

An individual-based, three-dimensional finite element model of the first metatarsal (MT I) bone was created with fine CT. The three-dimensional model of the bone was fixed proximally at the metatarsocuneiform joint and load was applied on the metatarsal head. Loading conditions were simulated, including muscular forces as described for a normal metatarsophalangeal (MTP) joint during three typical phases of gait as the combination of the load in the contact areas of the sesamoid bones and the base of the proximal phalanx. The resultant strain and stress distributions within the loaded MT I were calculated and visualized with the MTP in different positions.

Proximal crescentic metatarsal osteotomy: the effect of saw blade orientation on first ray elevation

BACKGROUND

Moderate and severe hallux valgus deformities generally require a proximal metatarsal osteotomy to correct a widened intermetatarsal angle. Although excellent results have been reported using the proximal crescentic osteotomy, concerns have been raised about the incidence of postoperative dorsal malunion, which may lead to transfer lesions. The objectives of this paper were to evaluate the influence of saw blade angulation on the final position of the first metatarsal and to test a new technique used to ensure proper orientation of the osteotomy.

METHODS

For part I of the study, 26 Sawbones specimens with hallux valgus deformities were corrected using a proximal crescentic osteotomy with the saw blade position incrementally rotated in the coronal plane. The sagittal change in the final position of the metatarsal was quantified radiographically and correlated to the saw blade orientation. For part II of the study, a Kirschner wire was placed in a vertical position into the medial cuneiform to serve as a guide for the crescentic saw blade in 13 cadaver feet with hallux valgus. Metatarsus primus elevatus was measured after surgical correction.

RESULTS

Part I of the study demonstrated a highly linear relationship (R2=0.95) between first metatarsal elevation and the orientation of the saw blade. Every 10-degree of saw blade angulation resulted in a 2-mm change in the sagittal position of the first metatarsal. In part II of the study, the average change in metatarsus primus elevation for the 13 specimens after surgical correction of the hallux valgus deformity was only 1.1 mm (range -3.9 to +4.9 mm). Eleven of the 13 specimens had less than 2.5 mm of elevatus.

CONCLUSION

Dorsal malunion of the first metatarsal after proximal crescentic osteotomy is a recognized complication. The final position of the hallux metatarsal is influenced by the coronal plane orientation of the saw. A new technique is described to aid the surgeon in proper alignment of the saw and help prevent excessive first ray elevation.

Stability of a cannulated screw versus a Kirschner wire for the proximal crescentic osteotomy of the first metatarsal: a biomechanical study

The purpose of this study was to compare the stability of a Kirschner wire (K-wire) versus a single cannulated screw for fixation of the proximal crescentic first metatarsal osteotomy. Seven matched pairs of fresh-frozen human cadaver first metatarsal specimens were dissected out en bloc at the first metatarsal-medial cuneiform complex; right and left specimens were randomized as to fixation. In screw specimens, a cannulated screw was mounted from the proximal medial side of the metatarsal, traversing osteotomy and engaging the lateral diaphyseal cortical bone. In the corresponding specimen, a K-wire was placed from the distal medial metatarsal cortex oriented as close to the longitudinal metatarsal axis as possible. Using a materials testing machine, a continuous load was applied to the plantar aspect of the metatarsal head at a rate of 5 mm/min until a displacement of 10 mm was reached. The following parameters were measured: initial stiffness of the entire specimen, stiffness of the osteotomy, the force required to create a 1-mm displacement, the force required to create a 0.15-mm gap across the osteotomy, and the ultimate force to create the 10-mm displacement. Both specimen and osteotomy stiffness were found to be significantly higher for screw fixation versus the K-wire (P <.05). Although there was also a difference in the force-to-failure load in favor of screw fixation, this result was found not found to be statistically significant.

The effect of screw type on the biomechanical properties of SCARF and crescentic osteotomies of the first metatarsal

The basilar crescentic osteotomy is a popular method for correcting moderate to severe hallux valgus. However, inadvertent dorsiflexion of the osteotomy can result from intraoperative malposition or from malunion after fixation failure. The mechanical properties of osteotomies are dependent on the nature of the osteotomy and the type of fixation. This study examines the mechanical properties of the SCARF and crescentic osteotomies of the first metatarsal by using a cannulated asymmetric pitched screw or AO cancellous screws. Sixteen human cadaveric first metatarsal specimens were tested in plantar to dorsiflexion cantilever bending by using a mechanical testing machine. The data was compared with our recent work on the mechanical properties of the SCARF and crescentic osteotomies. Ultimate load and stiffness of the SCARF osteotomy were superior to the crescentic osteotomy but were not dependent on screw type. Screw type was a prominent factor in the stiffness but not in the strength of the crescentic osteotomy. The ultimate load and the stiffness of SCARF osteotomy fixed with the cannulated asymmetric pitched screws were not significantly different compared with AO screws (ultimate load, 124.6 N [SD = 56.8] v 105.3 N [SD = 57.0]; stiffness, 52.0 N/mm [SD = 48.0] v 31.8 N/mm [SD = 19.0]). Modes of failure were fracture of the cortical bone bridge between the screw hole and the osteotomy in all crescentic osteotomies and fracture of the proximal dorsal bridge in all SCARF osteotomies. The superior mechanical properties of the SCARF osteotomy, fixed with cannulated asymmetric pitched screws, make this a more secure construct, with less risk of malunion than the crescentic osteotomy. Stiffness is an important mechanical factor that helps distinguish the mechanical performance of different osteotomy techniques.

The Ludloff metatarsal osteotomy: guidelines for optimal correction based on a geometric analysis conducted on a sawbone model

Ideally, osteotomy for hallux valgus deformities corrects varus angle and pronation, while minimizing elevation, depression, and shortening. We used a serial linkage tracking device to evaluate five variations of the Ludloff osteotomy, a stable proximal metatarsal osteotomy that incorporates an oblique dorsal to plantar cut and a lateral swing or pivoting correction of the dorsal fragment. A neutral osteotomy (perpendicular to the sagittal plane) yielded the greatest correction (14 degrees) but with shortening (average, 2.85 mm), elevation (average, 1.36 mm), and additional pronation (average, 1.88 degrees). The same osteotomy angled 10 degrees plantarly with 8 degrees of correction produced an average of 1.57 degrees of supination, 1.22 mm of depression and, 0.54 mm of shortening. Additional plantar inclination (20 degrees) and angular correction (16 degrees) yielded increased depression, supination, and shortening. The current findings provide guidelines to achieve the desired correction and rotation and suggest that optimal results can be obtained by performing this osteotomy angled 10 degrees plantarly with a correction of 8 degrees to 16 degrees.

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.

Six first metatarsal shaft osteotomies: mechanical and immobilization comparisons

Because malunion (usually with dorsal elevation of the first metatarsal) has been reported after the treatment of severe hallux valgus deformities by proximal osteotomies, the current study was designed to compare the sagittal stability of six different metatarsal shaft osteotomies: the proximal crescentic, proximal chevron, Mau, Scarf, Ludloff, and biplanar closing wedge osteotomies. A plate was used in the biplanar closing wedge osteotomy; all others used screws for fixation. Ten fresh-frozen, human anatomic lower extremity specimens were used for each osteotomy. Failure loads were measured as units of force (newtons) and converted to pressure (kilopascals). Then the F-Scan system, which uses a thin insole to measure plantar pressure, was used to evaluate the pressure under the first metatarsal of seven volunteers using four types of shoes. According to the results, in patients with normal bone stock who are compliant, any of the four shoe types tested may be used after a Ludloff, Scarf, biplanar wedge (plantar screw fixation), or Mau osteotomy, but the wedge-based shoe should be used after a proximal crescentic or chevron osteotomy or for patients with severe osteopenic bone.

A biomechanical comparison of the Z step-cut and basilar crescentic osteotomies of the first metatarsal

The basilar crescentic osteotomy is a popular procedure for the correction of moderate to severe hallux valgus deformity. Dorsiflexion due to malposition of the osteotomy, fixation failure, or late contracture of the soft tissues can lead to lateral metatarsalgia. This study compares the mechanical properties of the Z step cut osteotomy Scarff to those of the crescentic osteotomy in cantilever-bending. The ultimate load, maximum bending moment and energy absorbed were significantly greater for the Scarff osteotomy compared to those in the crescentic osteotomy (p < 0.001). Values for stiffness did not differ between the two osteotomies. Failure of the cortical bone-bridge between the screw-hole and the osteotomy was observed in all crescentic osteotomies, while fracture of the proximal dorsal bridge was seen in all Scarff osteotomies.