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

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.

Comparison of 4 Different Fixation Strategies for Midfoot Arthrodesis: A Retrospective Comparative Study

BACKGROUND

Midfoot arthrodesis is a common procedure performed both for arthritis and correction of deformity. The optimal fixation for midfoot arthrodesis has not been established, though numerous studies have been investigating the fixation techniques of midfoot arthrodesis. The purpose of this study was to compare the union rate of midfoot arthrodesis using 4 different fixation strategies and investigate risk factors of nonunion following midfoot arthrodesis.

METHODS

A retrospective chart review was performed for patients who underwent midfoot joint arthrodesis between January 2014 and May 2019. The rates of nonunion and postoperative complication were compared among 4 different fixation constructs: staple fixation, compression plate fixation, compression plate with lag screw fixation, and compression screw fixation. Predictors of nonunion following midfoot arthrodesis were investigated through a multivariable logistic regression analysis. A total of 95 patients (99 feet), including 240 midfoot joints were included in this study. The mean follow-up period was 78.4 weeks.

RESULTS

Overall, bony union was achieved in 86 out of 99 (86.9%) patients, which included 218 out of 240 (90.8%) midfoot joints. A significant difference in the nonunion rate according to the type of fixation construct was found (P = .011); the compression screw alone fixation construct was noted to have a significantly higher nonunion rate than other fixation constructs. Diabetes mellitus (odds ratio [OR] = 0.179 [95% CI: 0.059, 0.542]), the type of fixation construct (compression screw alone; OR =1.789 [95% CI: 1.071, 2.978]), lack of adjuvant bone graft (OR = 2.803 [95% CI: 1.081, 7.268], and postoperative nonanatomical alignment (OR = 3.937 [95% CI: 1.278, 12.126]) were identified as independent predictors of nonunion following midfoot arthrodesis.

CONCLUSION

The rate of nonunion following midfoot arthrodesis among 4 different commonly used fixation constructs was compared in this study. Risk factors of nonunion were investigated revealing that diabetes mellitus, compression screw fixation alone, lack of adjuvant bone graft, and postoperative nonanatomical alignment are independent predictors of nonunion following midfoot arthrodesis.

LEVELS OF EVIDENCE

Level III: Comparative cohort study.

The Efficiency of Highly Porous β-Tricalcium Phosphate With Bone Marrow Aspirate Concentrate in Midfoot Joint Arthrodesis

BACKGROUND

Nonunion is one of the most common and devastating complications following midfoot joint arthrodesis. Many different types of bone grafts and bone substitutes have been used to promote osseous fusion. However, there is no consensus on the gold standard bone grafting material and whether biologic materials should be used alone or in combination. The purpose of this study is to investigate the efficiency of highly porous β-tricalcium phosphate (β-TCP) with bone marrow aspirate concentrate (BMAC) in midfoot joint arthrodesis.

METHODS

This retrospective comparative study included patients who underwent midfoot joint arthrodesis using compression screws. Patients were classified into 2 groups: arthrodesis with highly porous β-TCP and BMAC (group A) and arthrodesis without them (group B). The osseous union rate was compared between the 2 groups. A total of 44 patients (46 feet) including 89 joints were included in this study.

RESULTS

There was a significant difference in the union rate between the 2 groups: 91.5% (43/47 joints) in arthrodesis with highly porous β-TCP and BMAC (group A) and 76.2% (32/42 joints) in arthrodesis without highly porous β-TCP and BMAC (group B; P = .048).

CONCLUSION

This study investigated the efficiency of highly porous β-TCP and BMAC to promote bony healing in midfoot joint arthrodesis. A significantly higher union rate was shown when arthrodesis was performed with highly porous β-TCP and BMAC, compared with arthrodesis performed without them. We suggest that highly porous β-TCP and BMAC can be a viable and effective adjunct to the fixation in midfoot joint arthrodesis.

LEVEL OF EVIDENCE

Level III: Retrospective comparative analysis.

A three-dimensional analysis of the tibialis anterior tendon: emphasizing tendon insertion patterns for effective repair and understanding hallux valgus development

PURPOSE

The present study aimed to evaluate the insertion site of the tibialis anterior tendon three-dimensionally.

METHODS

Seventy lower limbs were dissected. The tibialis anterior tendon was dissected to verify the insertion site to the medial cuneiform and the base of the first metatarsal bone. The three-dimensional (3D) territory of the tibialis anterior tendon insertion on the medial cuneiform and the first metatarsal bones was measured on a reconstructed 3D model.

RESULTS

The insertion pattern of the tibialis anterior tendon was classified into three types, the most common being Type I: a single tibialis anterior tendon dividing into two equal-sized bands to the medial cuneiform and base of the first metatarsal bone (57.1%, 40/70 of cases). The 3D territory of the tibialis anterior tendon was larger in the plantar aspect than in the medial side of both the medial cuneiform and the base of the first metatarsal bone. The width of the tendon inserted into the medial cuneiform was wider than that inserted into the first metatarsal bone.

CONCLUSION

The tibialis anterior tendon was more commonly attached to the plantar part than the medial part in both the medial cuneiform and the base of the first metatarsal bone. This anatomical information will help surgeons perform anatomical reconstruction of the tibialis anterior tendon, reduce further tendon damage in the first metatarsocuneiform joint area and also provide valuable knowledge to improve understanding of hallux valgus pathogenesis.

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.

Biomechanical Comparison of 5 Different Fixation Constructs in a Trapeziometacarpal Joint Arthrodesis Model

PURPOSE

Trapeziometacarpal joint (TMC) arthrodesis has a high rate of nonunion. This biomechanical analysis sought to determine the stiffness of 5 fixation methods in a TMC joint arthrodesis model.

METHODS

Five fixation constructs were tested in a validated porcine model: crossed 1.1-mm K-wires, crossed 1.6-mm K-wires, crossed headless compression screws (HCSs), compression plating (CP), and locked compression plating (LCP). The cantilever bending stiffness was measured in abduction, adduction, flexion, and extension. Samples were loaded to failure in extension, and the mode of failure was examined.

RESULTS

The crossed HCSs performed consistently well in all tests. Loading to failure resulted in screw pullout. In abduction and adduction, HCS and 1.6-mm K-wires were significantly stiffer than the other constructs. The mean load to failure in extension was similar in the HCS, CP, and LCP groups (304 N/mm, 311 N/mm, and 293 N/mm, respectively). There were no differences between CP and LCP in any biomechanical tests, and the mode of failure was through plate bending. The crossed 1.1-mm K-wires performed poorly in all tests.

CONCLUSIONS

Crossed HCS displayed the greatest overall stability. Standard plating in compression mode and LCP had a similar biomechanical performance.

CLINICAL RELEVANCE

The ideal construct stiffness required for the successful union after TMC joint arthrodesis is unknown, but HCS has the best overall biomechanical performance and, therefore, might be considered the best choice for this clinical setting.

Union Rates With the Use of Structural Allograft in Lapidus Arthrodesis: A Comparison Between Two Fixation Constructs

Although structural allograft has been previously described as acceptable practice for reconstructive foot and ankle surgery, results for an allograft bone wedge in Lapidus arthrodesis are unknown. Additionally, there is no consensus on the superiority of a single fixation construct in Lapidus cases. Our objective was (1) to report union rates for Lapidus arthrodesis with and without the use of an allograft bone wedge and (2) to determine if fixation construct impacts rates of union when using structural allograft. A review was performed for Lapidus cases with fixation constructs of 2 crossed compression screws (CS) and a medial locking plate with single transarticular screw (MPS), both with and without use of an allograft bone wedge. Inclusion required a CT scan to evaluate bony union. There was no significant difference in union rates (p = .41) between the use (90%) and the nonuse (97%) of an allograft bone wedge. Union rates were significantly different (p = .04) when comparing CS fixation (85%) and MPS fixation (98%). The comparative results between the fixation constructs highlight the importance of compression across the arthrodesis site as part of a robust fixation construct. Our findings demonstrate that the use of an allograft bone wedge in Lapidus arthrodesis may mitigate complications due to metatarsal shortening while providing satisfactory rates of union.

A Systematic Review of Intramedullary Fixation in Midfoot Charcot Neuroarthropathy

Charcot neuroarthropathy can cause severe deformity of the midfoot, and intramedullary use of beams and bolts has been utilized as a method of definitive stabilization. This systematic review evaluated the outcomes of intramedullary beaming in patients with Charcot neuroarthropathy and determined the methodological quality of the studies. Four online databases were searched: PubMed, MEDLINE (Clarivate Analytics), CINAHL (Cumulative Index to Nursing and Allied Health) and Web of Science (Clarivate Analytics). To assess the methodological quality of the studies, the Coleman Methodology Score was used. The data was pooled into 2 outcomes groups for comparison: (1) Studies that reported on the outcomes of Charcot specific implants (study group). (2) Studies that reported on the outcomes using non-Charcot specific implants (control group). After screening, 16 studies were included. Compared to our control group, our study group had significantly higher rates of overall hardware complications, hardware migration, surgical site infection, reoperation, and nonunion. The study group had significantly lower rates of limb salvage compared to the control group. Our study and control groups did not differ in the rates of hardware breakage, wound healing complications, or mortality. The limb salvage rate was 92% and 97% of patients were still alive at a mean follow-up of 25 months. The mean Coleman Methodology Score indicated the quality of the studies was poor and consistent with methodologic limitations. The quality of published studies on intramedullary implants for Charcot reconstruction is low. Complications when utilizing intramedullary fixation for Charcot reconstruction are high, whether or not Charcot specific implants are used.

Plantar Plating in the Modified Lapidus Procedure: Evaluation of Function and Impairment of the Tibialis Anterior Tendon

The modified "Lapidus" procedure (MLP) describes the arthrodesis of the first tarsometatarsal joint. We investigate if there are detectable changes of the tendon or the function of the muscle and clinical outcome after MLP. We reviewed 22 feet. All patients underwent magnetic resonance imaging (MRI) at an average of 27 (range, 12-49) months. Clinical outcome was evaluated using the European Foot and Ankle Society score. Strength was measured and complications were assessed. MRI revealed signs of tendinopathy of the tibialis anterior tendon in 13 feet (59%). The mean total European Foot and Ankle Society score at final follow-up was 17 (range, 6-24) points. The mean postoperative Visual Analog Scale score was 1.4 (range, 0-5). Range of motion and force data were not significantly different to the contralateral side. In conclusion, MRI showed signs of tendinopathy in 59%, which does not seem to affect clinical outcome, but has to be considered when choosing the desired implant and placement. MLP leads to high patient satisfaction rates and significant improvement at midterm follow up.

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.

Arthrodesis of the first metatarsophalangeal joint using an intraosseous fixation device

The complication rate for an arthrodesis of the first metatarsophalangeal joint remains high. To improve results, we used a complete intraosseous fixation device (IOFIX) with proposed biomechanical advantages. Our hypothesis is that this technique has at least an equal union rate and less hardware irritation compared to other techniques. Seventy procedures were performed in 55 patients. Average follow-up was 24.5 months. All patients returned to follow-up after 6 weeks and were evaluated for union. Fifty-nine feet (84%) completed full follow- up. Union occurred in 62 of 70 feet (88.5%). Eight feet had nonunion at 1 year follow-up. Average time to fusion was 51 days. Three of 59 feet had malunion. No hardware removal was necessary. In conclusion, an MTP1 arthrodesis using IOFIX provides consistent and good functional outcomes. Due to the low-profile design, no hardware removal was necessary. However, union rates seem slightly lower compared to other techniques.

Early Results and Patient-Reported Outcome Measures (PROMS) of an Intraosseous Device for Arthrodesis of the First Tarso-Metatarsal (TMT) Joint

BACKGROUND

We describe a new surgical technique for arthrodesis of the first tarso-metatarsal (TMT) joint using an intraosseous fixation device and the early results including patient-reported outcome measures (PROMS).

MATERIALS AND METHODS

Seventeen consecutive procedures with this method were included. Indication for surgery was hallux valgus. The average age was 42 years (range 26-65). PROMS were collected and the patients were asked to fill out a satisfaction questionnaire. A retrospective review of radiographs and electronic medical notes was conducted.

RESULTS

Overall fusion rate was 94%. Complications included a case of failed fusion, a superficial wound infection and a deep vein thrombosis (DVT). At a mean follow-up of 24 months (range 10-38) radiographic results demonstrated significant improvement in the intermetatarsal angle or IMA (11.7 ± 2.8 degrees to 6.9 ± 2.4 degrees, P < 0.001) and hallux valgus angle or HVA (28.1 ± 7.3 degrees to 12.2 ± 4.3 degrees, P < 0.001). The mean visual analog scale (VAS) score improved significantly from a mean of 7.6 (SD 0.85) preoperatively, to a mean of 2.1 (SD 1.83) post-operatively (P < 0.0001). The Manchester-Oxford Foot Questionnaire (MOXFQ) significantly improved from a mean of 35.8 (SD 10.2), to a mean of 9.2 (SD 17) (P < 0.0001). The final result was satisfactory for 88% of the patients.

CONCLUSIONS

The early results show intraosseous fixation to be a safe and efficient method for the fusion of the first TMT joint providing good patient satisfaction.

Biomechanical Evaluation of Tarsometatarsal Fusion Comparing Crossing Lag Screws and Lag Screw With Locking Plate

BACKGROUND

Tarsometatarsal (TMT) arthrodesis is a common operative procedure for end-stage arthritis of the TMT joints. To date, there is no consensus on the best fixation technique for TMT arthrodesis and which joints should be included.

METHODS

Thirty fresh-frozen feet were divided into one group (15 feet) in which TMT joints I-III were fused with a lag screw and locking plate and a second group (15 feet) in which TMT joints I-III were fused with 2 crossing lag screws. The arthrodesis was performed stepwise with evaluation of mobility between the metatarsal and cuneiform bones after every application or removal of a lag screw or locking plate.

RESULTS

Isolated lag-screw arthrodesis of the TMT I-III joints led to significantly increased stability in every joint (P < .05). Additional application of a locking plate caused further stability in every TMT joint (P < .05). An additional crossed lag screw did not significantly increase rigidity of the TMT II and III joints (P > .05). An IM screw did not influence the stability of the fused TMT joints. For TMT III arthrodesis, lag-screw and locking plate constructs were superior to crossed lag-screw fixation (P < .05). TMT I fusion does not support stability after TMT II and III arthrodesis.

CONCLUSION

Each fixation technique provided sufficient stabilization of the TMT joints. Use of a lag screw plus locking plate might be superior to crossed screw fixation. An additional TMT I and/or III arthrodesis did not increase stability of an isolated TMT II arthrodesis.

CLINICAL RELEVANCE

We report the first biomechanical evaluation of TMT I-III arthrodesis. Our results may help surgeons to choose among osteosynthesis techniques and which joints to include in performing arthrodesis of TMT I-III joints.

Intraosseous device for arthrodesis in foot and ankle surgery: Review of the literature and biomechanical properties

BACKGROUND

Arthrodesis is the surgical fusion of a diseased joint for the purposes of obtaining pain relief and stability. There have been numerous fixation devices described in literature for foot and ankle arthrodesis, each with their own benefits and drawbacks.

AIM

To review the use of intraosseous devices in foot and ankle surgery.

METHODS

There were 9 papers included in the review (6 clinical and 3 experimental studies) all evaluating arthrodesis in the foot and ankle using the IOFIX device (Extremity Medical™, Parsippany, NJ, United States). Outcome scores, union rates, as well as complications were analysed.

RESULTS

IOFIX appears to be safe and effective in achieving arthrodesis of the 1^st metatarsophalangeal, and talonavicular joints with early rehabilitation. In comparison to plate/screw constructs there were fewer soft tissue complications and issues of metalwork prominence. Cadaveric and biomechanical studies on the use of intramedullary fixation for fusion of the tarsometatarsal and ankle joint showed decreased load to failure, cycles to failure and stiffness in comparison to traditional fusion methods using plates and screws, however IOFIX devices produced higher compressive forces at the joint.

CONCLUSION

We describe the reasons for which this biomechanical behavior of the intraosseous fixation may be favorable, until prospective and comparative studies with larger sample size and longer follow-up confirm the effectiveness and limitations of the method.

Biomechanical evaluation of naviculocuneiform fixation with lag screw and locking plates

BACKGROUND

There have been no biomechanical evaluations of naviculocuneiform (NC) joint fixation. This study compared biomechanically 3 different fixation constructs for NC-1-3 joint fixation.

METHODS

The present study compared the three fixation constructs lag screw with locking plate for each NC joint, two crossed lag screws for each NC joint and a separate lag screw for each NC joint with bridging locking plates. NC-1-3 fixation was performed stepwise, and rotation of each joint was evaluated after the application of each lag screw or locking plate and their removal.

RESULTS

All examined fixation techniques led to a significant reduced rotation of the NC joints. For NC-1 rotation decreased from 2.8° (Range 1.2-6.6°) to 0.6° (0.2-3.0°) for lag screw and locking plate (p = 0.002) and from 5.0° (1.7-9.8°) to 1.0° (0.1-3.6°) for crossed lag screws (p = 0.002). For NC-2, locking plate constructs were better with 0.2° (0.1-0.5°) compared to crossed lag screw osteosynthesis with 0.9° (0.2-1.6°) (p = 0.011).

CONCLUSION

Each evaluated fixation technique led to a reduced NC joint rotation. The fixation of any NC joint had no relevant effect on the adjacent NC joints. The results might support surgeons treating NC joint disorders.

Effectiveness of the Lapidus plate system in foot surgery: A PRISMA compliant systematic review

Lapidus arthrodesis is an established standard procedure to correct various foot surgery problems and hallux limitus, hypermobility of the first ray, hallux abductus valgus, and symptomatic lesser metatarsal. After decades, many fixation methods in the orthopaedic surgery industry have been developed for decreasing complications and improving this technique. The aim of this PRISMA compliant systematic review is to analyse the effectiveness of several lapidus plate systems in foot surgery. We have carried out the first systematic review of the relevant published literature so as to systematically evaluate the scientific knowledge available now on this association, assigning predefined eligibility criteria. Fourteen studies were selected which had an overall of 738 cases. The first tarsal metatarsal joint and hallux valgus were treated by the application of different types of Lapidus plate system. The optimal level of the fixation in these procedures is related with the type and system insertion place of the plate with or without screw in each specific foot disease. There is an insufficient number of studies about the effectiveness of the different types of Lapidus plate system in foot surgery, and there is a need to increase outcomes knowledge on the level of the fixation, sort of the system, and insert place in foot surgery.

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.

Early Results of Immediate Weightbearing Following First Tarsometatarsal Joint Arthrodesis With Plantar Locking Plate and Dorsal Compression Screw

Arthrodesis of the first tarsometatarsal joint (TMT1) reduces pathologic angles at the anatomic center of rotation of angulation and presents a substantial correction potential in 3 planes in the treatment of hallux abductovalgus. The optimal fixation method remains unclear since prevailing dorsomedial locking plates and/or compression screws depict elevated implant-associated complications. Medical records of 49 patients that underwent 53 TMT1 arthrodeses in hallux abductovalgus interventions were included. Median average visual analog scale scores decreased (p < .001) from 6.8 (range 4-10) to 2.7 (range 0-10), first intermetatarsal angles were reduced (p < .001) from 17.39° (range 12°-28°) to 7.16° (range 3°-12°), standing lateral first metatarsal angles improved (p < .001) from 21.66° (range 12°-29°) to 23.94° (range 14°-31°) and tibial sesamoid positions were plantarized (p < .001) from 6.02° (range 4°-7°) to 2.79° (range 1°-6°). Plantar plating allowed immediate weightbearing with transition to normal shoe gear at 6 weeks. Complications occurred in 6 (11.34%) feet including 1 (1.89%) nonunion, 1 (1.89%) delayed union, 1 (1.89%) hallux varus, 1 (1.89%) incomplete recurrence, 1 (1.89%) minor dehiscence, and 1 (1.89%) hardware irritation. Plantar locking plates combined with a dorsal compression screw presented a favorable tension-side implant location that closed the fusion site under load. This facilitated substantial reductions in complications, pathologic angles, and pain.

The Lapidus Arthrodesis: Examining the Effect of the Metatarsal Base Transfixion Screw

The modified Lapidus bunionectomy is a useful and highly powerful procedure for correcting hallux abducto valgus. Traditionally reserved for "severe" deformities, this procedure has seen a recent resurgence in the podiatric community for its unique ability to achieve tri-planar correction of this challenging deformity. Although this procedure has been extensively studied in both biomechanical labs and the clinical arenas, no clear consensus has been achieved regarding optimal fixation for this thought-provoking procedure. The current study examined the differences in strength between commercially available 5-hole locking plates with interfragmentary compression vs a crossed-screw with a third "transfixation" screw construct in a controlled setting. Ten fresh-frozen cadaveric match pair limbs (20 total limbs) were used to complete this study. Ten limbs were randomly assigned to a 3-screw construct. The other 10 contralateral limbs were assigned to a commercially available 5-hole locking plate (5 stainless steel and 5 titanium alloy) with an interfragmentary lag screw construct. The first rays were then isolated and potted into a 4-point bending device. The specimens were loaded to failure in a servohydraulic load frame at a controlled rate. Failure was defined as catastrophic or 3 mm of plantar gapping at the arthrodesis site. The mean maximal load to failure was 310.9 ± 109.4 N for the 3-screw construct. The mean maximal load to failure for the locking plate constructs was 264.1 ± 100.9 N. This difference was not statistically significant (p = .328). These results suggest that a 3-screw construct for Lapidus arthrodesis is as strong as commercially available locking plate constructs.

Revision of Malaligned Lapidus and Nonunited Lapidus

"Lapidus arthrodesis is becoming more of a common procedure for treatment of hallux valgus deformities. Like other procedures, complications are possible. The common complications associated with Lapidus arthrodesis procedures include nonunion and malunion. Malunion is typically broken down into recurrence, elevated first ray, shortened first ray, or plantarflexed first ray. This article discusses these common complications after Lapidus arthrodesis.

Anatomical study of Lapidus arthrodesis using two different plantar plate systems

BACKGROUND

First tarsometatarsal arthrodesis (modified Lapidus procedure) constitutes a sufficient treatment for moderate to severe hallux valgus deformity and first ray instability. The plantar plate arthrodesis was shown to provide superior mechanical stability and less postoperative complications than screw fixation or dorsal plating. Nevertheless, the in-brought hardware may cause irritation of the tibialis anterior or peroneus longus tendon requiring explantation of the material in some cases. The purpose of this study was to investigate the potential of tendon irritation after plantar first tarsometatarsal joint arthrodesis in a cadaver study.

METHODS

Plantar plate arthrodesis was performed as in real surgery on twelve pairs of fresh frozen cadaveric feet. Two different plate systems were randomly allocated to each pair of feet. After plate fixation careful dissection of the feet followed to analyze potential tendon irritation and to determine a "safe zone" for plantar plate placement.

RESULTS

A "safe zone" between the insertion sties of tibialis anterior and peroneus longus tendon was found and proven to be sufficiently exposed using a standard medio-plantar approach. Both plates were fixed in this zone without compromising central tendon parts. Peripheral tendon parts were irritated in 42% using Darco Plantar Lapidus Plating System® (Wright Medical, Memphis, TN) and in 8% using the Plantar Lapidus Plate® (Arthrex, Naples, FL). Bending of the anatomically preshaped plates is often necessary to ensure optimal fit on the bone surface.

CONCLUSIONS

Modified Lapidus procedure with plantar plating of the first tarsometatarsal joint can be performed safely without compromising central tendon parts via standard medio-plantar approach.

LEVEL OF CLINICAL EVIDENCE

5, Cadaver Study.

Biomechanical Comparison of First Tarsometatarsal Arthrodesis Constructs Over Prolonged Cyclic Testing

Background:

Traditionally, a lengthy period of nonweightbearing is required following arthrodesis of the first tarsometatarsal (TMT) joint in order to provide a stable healing environment for the bones. The goal of this research was to determine the resistance to plantar gapping of 2 locked intramedullary devices and a medial plate with crossing screw, all specifically designed for hallux valgus correction, and compare them to traditional 2–crossing screw fixation under a cyclic testing protocol. We hypothesized the locked intramedullary devices and the medial plate with crossing screw would better resist plantar gapping.

Methods:

Forty cadaver specimens received 1 of 4 operative treatments: a locked intramedullary device with 2 points of fixation in the cuneiform, a locked intramedullary device with 1 point of fixation in the cuneiform, a medial plate with crossing screw, or 2 crossing screws. We applied dorsiflexion bending forces to the first TMT joint using a cadaveric fatigue model for 20 000 cycles. The plantar gap between the metatarsal and cuneiform was measured at the beginning and end of cyclic testing. Thirty-six specimens were included in the final data set.

Results:

Both locked intramedullary device groups and the medial plate with crossing screw group exhibited significantly less gap widening compared to the 2–crossing screw group (vs 3-hole intramedullary device, P = .014; vs 4-hole intramedullary device, P = .010; and vs medial plate with crossing screw, P = .044). The intramedullary device groups were the most stable during the cyclic fatigue test, exhibiting the smallest gap widening. The medial plate with crossing screw fixation was also more stable than crossing screws in the cyclic fatigue model.

Conclusions:

The locked intramedullary devices and medial plate with crossing screw resisted plantar gapping better than 2 crossing screws when used for first TMT arthrodesis.

Clinical Relevance:

These results indicate that locked intramedullary devices and medial plates with crossing screws may promote superior bone healing and may better tolerate early weightbearing compared with 2 crossing screws.

The computed tomographybased anatomy of the ossa cuneiformia

There is a lack of basic anatomic information regarding the ossa cuneiformia. The aim of the present descriptive study was the detailed evaluation of the anatomy of the ossa cuneiformia. We analyzed 100 computer tomography scans of feet without deformities or previous trauma. The length, height and width of each cuneiforme and their articular surfaces were assessed. We itemized the data to gender differences and to foot length. The medial cuneiforme os had a length of 24.0 mm ± 2.4 (mean ± standard deviation), a width of 17.3 mm ± 2.8 and a height of 28.0 mm ± 3.4. The respective values for the intermediate cuneiforme were 18.2 mm ± 2.1, 15.8 mm ± 2.1 and 22.5 ± 2.2 and for the lateral cuneiforme 26.4 mm ± 2.7, 17.2 mm ± 2.9 and 22.8 mm ± 2.9. We found statistical relevant differences regarding gender and foot length subgroups whereas not for all parameters. The present study illustrates basic anatomic data regarding the ossa cuneiformia. This information might be helpful for implant design and placement during midfoot surgery.

Lower Bone Density on Preoperative Computed Tomography Predicts Periprosthetic Fracture Risk in Total Ankle Arthroplasty

BACKGROUND:

The effect of bone mineral density (BMD) on outcomes from total ankle arthroplasty (TAA) has not been studied. BMD can be estimated by measuring Hounsfield units (HU) on standard computed tomography (CT), which is frequently performed prior to TAA. We aimed to identify whether tibial and talar HU measured from preoperative CT scans were associated with periprosthetic fracture or revision risk in patients undergoing TAA.

METHODS:

A prospectively collected database was used to retrospectively screen all patients undergoing primary TAA. Only patients with a preoperative CT within 1 year of surgery were included. Primary outcomes were periprosthetic fracture and prosthetic revision. HU were measured on axial CT cuts in the distal tibia and talus. Additional patient factors analyzed included age, sex, weight, body mass index (BMI), tobacco use, presence of rheumatoid arthritis, and preoperative deformity. A total of 198 ankles were included, with a mean 2.4 years of follow-up.

RESULTS:

There were 7 intraoperative and 9 postoperative periprosthetic fractures (3.5% and 4.5%, respectively). Seven patients (3.5%) underwent prosthetic removal or revision. Lower tibial and talar HU, lower weight, and lower BMI were associated with periprosthetic fractures ( P < .05). After controlling for age, sex, and weight, only tibial HU was significantly associated with periprosthetic fracture ( P = .018). All intraoperative fractures occurred in patients with tibial HU less than 200. None of the patient factors analyzed were associated with revision.

CONCLUSIONS:

Lower tibial HU on preoperative CT was strongly associated with periprosthetic fracture risk with TAA. In patients with tibial HU less than 200, surgeons may consider prophylactic internal fixation of the medial malleolus.

LEVEL OF EVIDENCE:

Level III, retrospective cohort study.

Biomechanical Characteristics of Biplane Multiplanar Tension-Side Fixation for Lapidus Fusion

Although plating on the plantar, tension-side of the metatarsocuneiform joint provides an inherent biomechanical advantage for Lapidus arthrodesis, it has not been widely adopted owing to the morbidity associated with plantar application. To overcome these limitations, a modification to 90-90 locked biplanar plating was developed to provide the biomechanical advantages of multiplanar fixation and tension-side fixation, allowing application through a conventional incision. We tested the hypothesis that biplanar plating with tension-side fixation (low-profile straight dorsal plate and anatomic medial-plantar plate) would demonstrate improved mechanical stability compared with a previously tested 90-90 biplanar construct (small straight plate dorsally and medially) under cyclic loading. Both constructs were tested in static load to failure (3 pairs) and cyclic loading (10 pairs) with plantar cantilever bending using surrogate anatomic bone models. With static ultimate failure, the biplanar plate construct with tension-side fixation failed at a significantly greater failure load than did the straight biplanar plate construct (247.3 ± 18.4 N versus 210.9 ± 10.4 N; p = .04). With cyclic failure testing, the biplanar plate construct with tension-side fixation endured a significantly greater number of cycles (206,738 ± 49,103 versus 101,780 ± 43,273; p < .001) and a significantly greater dynamic failure load (207.5 ± 24.3 N versus 162.5 ± 20.6 N; p < .001) compared with the straight biplanar plate construct. These results have demonstrated that under simulated static and cyclic Lapidus arthrodesis loading, biplanar plating with tension-side fixation provides superior strength compared with the straight biplanar construct. Thus, this construct shows promise for clinical application as a practical approach to tension-side fixation and an early return to weightbearing after Lapidus fusion.

Effect of Fixation Type and Bone Graft on Tarsometatarsal Fusion

BACKGROUND:

End-stage tarsometatarsal (TMT) arthritis is commonly treated with arthrodesis of involved joints. Fixation hardware can consist of varying combinations of screws, plates, and staples with or without supplemental bone graft. There are limited data to demonstrate either superiority of a given fixation method or the impact of bone graft on fusion rates. The purpose of this study, therefore, was to determine whether nonunion rates after TMT arthrodesis were influenced by either the use of screw vs plate fixation or the addition of bone graft vs no bone graft.

METHODS:

All patients older than 18 years undergoing arthrodesis for TMT arthritis between July 1991 and July 2016 were identified retrospectively. Exclusion criteria included less than 12 months follow-up, prior midfoot surgery, any added procedure beyond TMT arthrodesis using plates or screws, and acute foot trauma. All patients with radiographic or clinical nonunion, including those requiring revision surgery, were identified. Demographic data and associated risk factors were recorded via chart and radiographic image review. Eighty-eight patients (88 feet, mean follow-up: 75.1 ± 51.4; range, 12-179), with a total of 189 joints and who met enrollment criteria were treated by 9 different surgeons with arthrodesis.

RESULTS:

The overall nonunion rate was 11.4%. Significant independent risk factors associated with nonunion were (1) arthrodesis using plate fixation with all screws through the plate (odds ratio [OR], 6.2; 95% confidence interval [CI], 1.8-21.3; P = .004), (2) smoking during the perioperative period (OR, 7.9; 95% CI, 2.1-30.2; P = .002), and (3) postoperative nonanatomic alignment (OR, 11.2; 95% CI, 2.1-60.8; P = .005). Bone graft utilization was found to significantly lower the rate of nonunion (OR, 0.2; 95% CI, 0.1-0.6; P = .006).

CONCLUSION:

Isolated plate fixation, smoking, and postoperative nonanatomic alignment appear to significantly increase the rate of nonunion among patients undergoing TMT arthrodesis for midfoot arthritis. Concomitant use of autogenous bone graft significantly decreased this risk.

LEVEL OF EVIDENCE:

Level III, retrospective comparative study.

The impact of medial cuneiform bone variant measures on the severity of hallux valgus: A radiological study

PURPOSE

The aetiology of hallux valgus (HV) is multifactorial in nature. The first metatarsocuneiform joint obliquity is a well-known factor in the development of the deformity. The purpose of this study is to assess the correlation of different medial cuneiform radiological measures on the severity of HV.

METHODS

Full weight-bearing anteroposterior views of 152 feet with different clinical severity are divided into four groups: without deformity and with mild, moderate and severe deformities. Three medial cuneiform angles were assessed, namely, the first metatarsocuneiform angle (MCA), the first metatarsocuneiform slope angle (MCSA) and the medial cuneiform lateral tilt angle (MCLTA).

RESULTS

The first MCA average values of groups 1, 2, 3 and 4 were (25.16 ± 5.74°, 27.38 ± 6.14°, 30.27 ± 5.62° and 34.28 ± 6.81°), respectively. Statistical differences were detected between groups (1, 3) and (1, 4) with p values of 0.034 and 0.001, respectively. The average values of the first MCSA of groups 1, 2, 3 and 4 were 19.26 ± 4.97°, 22.54 ± 5.62°, 26.13 ± 6.36° and 32.17 ± 5.85°, respectively. Significant differences were detected between groups (1, 3) and (1, 4) with p values of 0.04 and 0.023, respectively. Average values of the MCLTA of groups 1, 2, 3 and 4 were 80.85 ± 4.49°, 74.56 ± 5.28°, 62.38 ± 6.34° and 58.78 ± 6.25°, respectively. Statistical significances were detected between groups (1, 2), (1, 3) and (1, 4) with p values of 0.026, 0.018 and 0.001, respectively.

CONCLUSIONS

Increasing the medial cuneiform lateral tilt increases the first metatarsocuneiform articulation obliquity demonstrated by the increase in the first MCSA which in term enhances the progression of varus deformity of the first metatarsal bone explained by the increase in the first MCA.

Biomechanics of common fixation devices for first tarsometatarsal joint fusion-a comparative study with synthetic bones

BACKGROUND

Hallux valgus disease is a common deformity of the forefoot. There are currently more than 100 surgical approaches for operative treatment. Because hypermobility of the first tarsometatarsal joint is considered to be causal for hallux valgus disease, fusion of the tarsometatarsal joint is an upcoming surgical procedure. Despite the development of new and increasingly stable fixation devices like different locking plates, malunion rates have been reported in 5 to 15% of cases.

METHODS

Biomechanical comparison of three commonly used fixation devices (a dorsal locking plate, a plantar locking plate, and an intramedullary fixation device) was performed by weight-bearing simulation tests on synthetic bones. Initial compression force and stiffness during simulation of postoperative weight-bearing were analysed.

RESULTS

Fixation of the first tarsometatarsal joint with the plantar plate combination demonstrated a higher stiffness compared to fixation with the intramedullary implant or the medial locking plate. The intramedullary device provided the highest initial compression force. Failure was detected in the following ranking: (1) the angle-stable intramedullary fixation device, (2) the medial located plate, and (3) the plantar locking plate.

CONCLUSION

The intramedullary device demonstrated the highest initial compression force of the three tested implants. The plantar locking plate showed the best overall stability during weight-bearing simulation. Further clinical research is necessary to analyse if the intramedullary fixation device needs a longer period of non-weight-bearing to reach a better non-union rate compared to the plantar locking plate.

Appropriate Area for Operative Procedures Near Tibialis Anterior Tendon Insertion: A Cadaveric Study

BACKGROUND

The tibialis anterior tendon has its insertion sites on both the medial and plantar surfaces of the medial cuneiform and the base of the first metatarsal. Operative procedures near those areas, especially at the first metatarsocuneiform joint, may disturb tendon insertions and cause irritation or functional impairment of the tendon.

METHODS

Tibialis anterior tendons and their insertion sites were dissected and examined from 46 cadaveric feet (19 female and 27 male cadavers, aged between 33 and 86 years, with a mean of 68.5 ± 14.3 years). The greatest lengths and widths of the tendon attachments on the bony surface of the medial cuneiform and base of the first metatarsal, on both the medial and plantar surfaces, were measured and analyzed. The measurement reliability was evaluated by using the intraclass correlation coefficient.

RESULTS

Most of the tibialis anterior tendon insertions were found to be longer at the medial cuneiform than at the base of the first metatarsal (mean, 8.3 and 5.4 mm; P < .001), but the widths were almost similar (mean, 11.0 and 10.4 mm; P = .079). When focusing on each bone, the widths of the tendon attachments on the medial and plantar surfaces of the medial cuneiform were equivalent (mean, 5.4 and 5.6 mm; P = .584). At the base of the first metatarsal, the tendon attachment on the plantar surface was found to be wider than on the medial surface (mean, 7.0 and 3.4 mm; P < .001).

CONCLUSION

The widths of the tibialis anterior tendon insertions on the medial and plantar surfaces of the medial cuneiform were equal, as were the total widths of insertions on the medial cuneiform and on the base of the first metatarsal. However, the width of insertions on the medial surface of the first metatarsal was significantly smaller than on the plantar surface, and the total length of insertions at the medial cuneiform was longer than at the first metatarsal.

CLINICAL RELEVANCE

This study provides information about characteristics of the tibialis anterior tendon insertions, particularly details of the dimensions on each surface of the bones. This knowledge enables surgeons to minimize the risk of irritation or tendon injuries during operations near the base of the first metatarsal and medial cuneiform area.

Biomechanical Comparison of Fixation Devices for First Metatarsocuneiform Joint Arthrodesis

Common surgical treatment of first tarsal-metatarsal arthritis is by first metatarsocuneiform joint arthrodesis. While crossed-screw and locking plate fixation are the most widely used methods, a novel construct was designed to alleviate soft tissue irritation while still providing stable fixation. Using anatomic first metatarsal and medial cuneiform composites, we compared 3 arthrodesis implants (crossed-screw, dorsal locking plate, and IO Fix) under 2 cyclic bending loading scenarios (cantilever and 4-point bending). Additionally, the optimal orientation (plantar-dorsal or dorsal-plantar) of the IO Fix construct was determined. Failure load, diastasis, joint space angle, and axial and angular stiffness were determined. Both crossed-screw fixation and the IO Fix constructs experienced significantly higher failure loads than the dorsal locking plate during both loading scenarios. Additionally, they had lower plantar diastasis and joint space angle at failure than the plate. Moreover, the plantar-dorsal IO Fix construct was significantly stiffer than the crossed-screw during cantilever bending. Finally, the plantar-dorsal orientation of the IO Fix device had higher failure load and lower diastasis and angle at failure than in the dorsal-plantar orientation. The results suggest that the IO Fix system can reduce motion at the interfragmentary site and ensure compression for healing comparable to that of the crossed-screw fixation.

LEVELS OF EVIDENCE

Level V: Bench testing.

Early results of an intraosseous device for arthrodesis of the hallux metatarsophalangeal joint

BACKGROUND

Arthrodesis of the hallux metatarsophalangeal (MTP) joint is commonly done as a primary procedure either to correct severe hallux valgus deformities or for rheumatoid arthritis, hallux rigidus, in patients with neuromuscular disorders and as a salvage procedure for failed bunion surgery or infection. Prominent metalwork frequently can cause soft tissue impingement and thus require removal. In contrast, osteosynthesis with a completely intraosseous implant has the advantage of less damage to the periosteal circulation. We describe a surgical technique and the early results of arthrodesis of the hallux metatarsophalangeal (MTP) joint using an intraosseous fixation device.

MATERIALS AND METHODS

Twelve consecutive patients operated with this method were retrospectively reviewed. The average age was 57 years (range 44-88 years). A retrospective review of radiographs and electronic medical notes was conducted. The patients were also asked to fill a satisfaction questionnaire.

RESULTS

Overall fusion rate was 91% with a mean hallux valgus angle of 15° (range 4-20°) and a mean dorsiflexion angle of 20° (range 7-30°). Complications included a case of failed fusion, a delayed union, and a case of persisting transfer metatarsalgia. At a mean followup of 14 months (range 5-28 months), the mean visual analog scale improved significantly from a mean of 8.4 (range 7-10) preoperatively, to a mean of 3.1 (range 0-7) postoperatively (P < 0.0001). The mean American Orthopaedic Foot and Ankle Society hallux score also significantly improved from 29.4 (range 10-54) to a mean of 73.3 (range 59-90) (P < 0.0001). The final result was satisfactory for 83% of the patients.

CONCLUSIONS

The early results show intraosseous fixation to be a safe and efficient method for the fusion of the hallux MTP joint providing relief from pain and patient satisfaction.

Intramedullary and intra-osseous arthrodesis of the hallux metatarsophalangeal joint

PURPOSE

To review the outcome of arthrodesis of the hallux metatarsophalangeal (MTP) joint in 23 patients.

METHODS

Records of 9 men and 14 women aged 27 to 88 (mean, 57) years who underwent arthrodesis of the hallux MTP joint using an intramedullary device and an intra-osseous device were reviewed. Indications for surgery were severe hallux valgus (n=15), hallux rigidus (n=6) and rheumatoid arthritis (n=2). Outcome measures included visual analogue score (VAS) for pain, the American Orthopaedic Foot and Ankle Society (AOFAS) hallux score, bone union, hallux valgus angle (HVA), dorsiflexion angle (DA), complications, revision, and patient satisfaction.

RESULTS

The mean follow-up was 19 (range, 6-38) months. The mean AOFAS score improved from 29 to 75.4 (p<0.0001) and the mean VAS for pain improved from 8.1 to 2.4 (p<0.0001). 20 (86%) of the patients were satisfied with the outcome. The mean HVA was 14º and the mean DA was 22º. 19 (83%) of the toes had a well-aligned hallux. 21 (91%) of the patients achieved arthrodesis of the hallux MTP joint. The remaining 2 patients underwent revision surgery for failed fusion or infected non-union; they continued to have transfer metatarsalgia despite bone union.

CONCLUSION

The intramedullary and intra-osseous devices for arthrodesis of the hallux MTP joint achieved good outcome in terms of AOFAS score, VAS for pain, HVA, DA, bone union, and patient satisfaction.

Placement of Plantar Plates for Lapidus Arthrodesis: Anatomical Considerations

BACKGROUND

The modified Lapidus procedure is an accepted treatment option for patients with moderate to severe hallux valgus. Placing a plate plantar on the tension side of the arthrodesis has been shown to be biomechanically superior and has provided good clinical results. There is some concern about interference of the plantar placed plates on the tendon insertions. The purpose of this study was to determine a "safe zone" for plantar plate placement without irritation of the tendons.

METHODS

Twenty-nine embalmed right feet were used for this study. The anatomy of the insertion of the peroneus longus (PL) tendon and tibialis anterior (TA) tendon on the medial cuneiform and first metatarsal were analyzed. Six different plate designs for plantar plating of the first tarsometatarsal fusion were included. The fit to the bone and contact to tendon insertion were analyzed.

RESULTS

The PL showed a main insertion to the first metatarsal and a lesser insertion to the medial cuneiform. The TA inserted onto the medial cuneiform and first metatarsal in all cases in our series. There was a "safe zone" between the TA and PL insertion areas for plate placement. Straight, Y- and U-shaped plates could be placed without compromising the tendon insertion. Depending on the design, even preshaped plates may have to be bent to allow a good fit to the plantar side of the first tarsometatarsal joint.

CONCLUSION

Plantar plating for modified Lapidus arthrodesis can be safely performed, without damaging the plantar tendon insertion area of the PL and TA.

CLINICAL RELEVANCE

The exact knowledge of the anatomy of the plantar region of the tarsometatarsal joint can help to improve plate placement.