RESULTS

There were 5 females, 4 males; 7 left, 2 right. Mean age of limb at death was 66years. There was no baseline deformity identified that precluded the inclusion of thelimbs in the study as determined by clinical and fluoroscopic examination. There wasa statistically significant relationship (p<0.05) between frontal plane rotation and firstMTPJ ROM in a simulated first TMTJ arthrodesis model with increased valgusposition resulting in decreased first MTPJ ROM.

LITERATURE REVIEW

Hallux valgus is one of the most commondeformities of the foot and is present in greater than20% of adults (1). While often perceived asdeformity within the transverse and sagittal planes,pathologic frontal plane deformity exists withinhallux abducto valgus (HAV) as demonstrated by invivo and in vitro investigations (2-7). Thepathologic triplanar nature of HAV deformity hasrecently received increased attention with emphasison addressing the frontal plane in surgicalcorrective procedures (8-11).

The first TMTJ arthrodesis is indicated formoderate to severe HAV deformity with first rayhypermobility (12). Additionally, the TMTJarthrodesis allows for correction at the center ofrotation of angulation of the deformity. This apexof deformity allows for deformity correction withinall three planes without creating secondarydeformity (13). With correction in the frontal plane,radiographic evidence of improved anatomicalignment and sesamoid position has decreased theneed for procedures at the MTPJ level (8-11).

Diminished motion of the first MTPJ has beenfound after HAV correction and has been linked todecreased patient satisfaction (14-17). Some haveattributed the decreased postoperative ROM todistal soft tissue procedures such as a lateral release(18-20). While lateral release may in part be acause for decreased ROM, we question whetherretained frontal plane deformity with first TMTJarthrodesis may be a contributing etiology fordecreased ROM at the first MTPJ.

Little has been studied regarding the effectsof first TMTJ arthrodesis on first MTPJ ROM.Meyerson and colleagues found the MTPJ ROM toaverage 85% of normal following first TMTJarthrodesis, conversely Perez and colleagues foundthe TMTJ arthrodesis to actually result in adecreased resistance to dorsiflexion of 25%postoperatively, without negative effects to the firstMTPJ (21, 22). Certainly, further works are needed.

STATEMENT OF PURPOSE

Frontal plane rotation of the first metatarsal has been described in bunion deformities; however,the consequences of uncorrected frontal plane deformity with first tarsometatarsal joint (TMTJ) arthrodesishave yet to be fully understood. The purpose of this study is to determine if a significant relationshipexists between first metatarsal frontal plane position and first metatarsophalangeal joint (MTPJ) rangeof motion (ROM) with first TMTJ arthrodesis

REFERENCES

1. Nix S, Smith M, Vicenzino B. Prevalence of hallux valgus in the general population: a systematic review and meta-analysis. J Foot Ankle Res 27;3:21, 2010. 2. Eustace S, O'Byrne J, Stack J, Stephens MM. Radiographic features that enable assessment of first metatarsal rotation: the role of pronation in hallux valgus. Skeletal

Radiol 22(3):153-6, 1993. 3. Durrant MN, McElroy T, Durrant L. First metatarsophalangeal joint motion in Homo sapiens: theoretical association of two-axis kinematics and specific morphometrics.

J Am Podiatr Med Assoc 102(5):374-89, 2012. 4. Mortier JP, Bernard JL, Maestro M. Axial rotation of the first metatarsal head in a normal population and hallux valgus patients. Orthop Traumatol Surg Res 98(6):677-

83, 2012. 5. Collan L, Kankare JA, Mattila K. The biomechanics of the first metatarsal bone in hallux valgus: a preliminary study utilizing a weight bearing extremity CT. Foot Ankle

Surg 19(3):155-61, 2013. 6. Dayton P, Feilmeier M, Hirschi J, Kauwe M, Kauwe JS. Observed Changes in Radiographic Measurements of the First Ray after Frontal Plane Rotation of the First

Metatarsal in a Cadaveric Foot Model. J Foot Ankle Surg 53(3):274-8, 2014.7. Kim Y, Kim JS, Young KW, Naraghi R, Cho HK, Lee SY. A new measure of tibial sesamoid position in hallux valgus in relation to the coronal rotation of the first

metatarsal in CT scans. Foot Ankle Int 36(8):944-52, 2015.8. Dayton P, Feilmeier M, Kauwe M, Hirschi J. Relationship of frontal plane rotation of first metatarsal to proximal articular set angle and hallux alignment in patients

undergoing tarsometatarsal arthrodesis for hallux abducto valgus: a case series and critical review of the literature. J Foot Ankle Surg 52(3):348-54, 2013. 9. Dayton P, Kauwe M, DiDomenico L, Feilmeier M, Reimer R. Quantitative analysis of the degree of frontal rotation required to anatomically align the first metatarsal

phalangeal joint during modified tarsal-metatarsal arthrodesis without capsular balancing. J Foot Ankle Surg Oct 2015 Epub.10. Klemola T, Leppilahti J, Kalinainen S, Ohtonen P, Ojala R, Savola O. First tarsometatarsal joint derotational arthrodesis--a new operative technique for flexible hallux

valgus without touching the first metatarsophalangeal joint. J Foot Ankle Surg 53(1):22-8, 2014. 11. DiDomenico LA, Fahim R, Rollandini J, Thomas ZM. Correction of frontal plane rotation of sesamoid apparatus during the Lapidus procedure: a novel approach. J Foot

Ankle Surg 53(2):248-51, 2014. 12. Vanore JV, Christensen JC, Kravitz SR, et al. Clinical Practice Guideline First Metatarsophalangeal Joint Disorders Panel of the American College of Foot and Ankle

Surgeons. Diagnosis and treatment of first metatarsophalangeal joint disorders. Section 1:hallux valgus. J Foot Ankle Surg 42:112-123, 2013.13. Paley D, Herzenberg JE, editors. Principles of Deformity Correction, Springer-Velag,Berlin, 2005.14. Samimi R, Green DR, Malay DS. Evaluation of first metatarsophalangeal range of motion pre and post bunion surgery: A clinical and radiographic correlation with

stress lateral dorsiflexion views; A retrospective approach. Podiatry Institute 16, 2010.15. Ozkurt B, Aktekin CN, Altay M, Belhan O, Tabak Y. Range of motion of the first metatarsophalangeal joint after chevron procedure reinforced by a modified

capsuloperiosteal flap. Foot Ankle Int 29(9): 903-909, 2008.16. Jones CP, Coughlin MJ, Brebing BR, Dennedy MP, Shurnas PS, Viladot R, Golano P. First metatarsophalangeal joint motion after hallux valgus correction: A cadaver

study. Foot Ankle Int 26(8): 614-619, 2005.17. Milnes HL, Kilmartin TE, Dunlop G. A pilot study to explore if the age that women undergo hallux valgus surgery influences the post-operative range of motion and

level of satisfaction. The Foot 20(4): 109-113, 2010.18. Lee HJ, Chung JW, Chu IT, Kim YC. Comparison of distal chevron osteotomy with and without lateral soft tissue release for the treatment of hallux valgus. Foot Ankle

Int 31(4): 291-295, 2010.19. Ahn JY, Lee HS, Chun H, Kim JS, Seo DK, Choi YR, Kim SW. Comparison of open lateral release and transarticular lateral release in distal chevron metatarsal

osteotomy for hallux valgus correction. Int Ortho 37: 1781-1787, 2013.20. Granberry WM, Hickey CH. Hallux valgus correction with metatarsal osteotomy: effect of a lateral distal soft tissue procedure. Foot Ankle Int 16(3):132-8, 1995. 21. Myerson M, Allon S, McGarvey W. Metatarsocuneiform arthrodesis for management of hallux valgus and metatarsus primus varus. Foot Ankle 13(3):107-15, 1992. 22. Perez HR, Reber LK, Christensen JC. Effects on the metatarsophalangeal joint after simulated first tarsometatarsal joint arthrodesis. J Foot Ankle Surg 46(4):242-7, 2007.

DISCUSSION

This cadaveric investigation demonstrated a statistically significantrelationship between increased frontal plane rotation and decreased first MTPJ ROMwith TMTJ arthrodesis. As such, these findings assist in the overall understanding oftriplanar bunion correction and display potential consequences of residual frontalplane deformity. It is possible that the discrepancy between our results and the resultsfound by Perez and colleagues was secondary to the nonpathologic position of thefirst MTPJ at the testing construct in their study population. However, furtherinvestigation would be warranted.

There are inherent weaknesses to this investigation, including the cadavericnature, the small sample size and the inability to eliminate all confounding factors.Further in vivo investigation with patient outcomes would be warranted for a betterdepiction of the consequences of uncorrected frontal plane deformity with first TMTJarthrodesis.

It is our hope that this anatomic biomechanical investigation will stimulatefurther works on this topic due to the statistically significant relationship betweenfirst metatarsal frontal plane position and first MTPJ ROM with simulated first TMTJarthrodesis demonstrated in our study.

PROCEDURES

Baseline deformity of each limb wasdetermined by clinical and fluoroscopicexamination. Limbs were excluded if firstMTPJ pathology was identified. Afterdissection of the first TMTJ, simulated firstTMTJ arthrodesis was attained by fixation ofthe first metatarsal base to the customexperimental loading construct therebyeliminating proximal influence (Figure 1). Nodissection of the 1st MTPJ was performed as topreserve anatomic relationships and diminishdistal soft tissue influence. Utilizing a 40N-applied force at a hinged platformattachment, resultant first MTPJ enddorsiflexory ROM values were recordedusing the bisection of the hallux to thebisection of the first metatarsal. Repeat trialsat 10 degree increments of valgus frontalplane rotation were completed (Table 1). Twotrials were conducted and the means taken(Figure 2). Data were collected and analyzedby 1-way ANOVA with Geisser-Greenhousecorrection to determine if a statisticallysignificant effect of frontal plane rotation onfirst MTPJ ROM exists (p<0.05).

Figure 1: Experimental Loading Construct

Table 1: Collected Data

30.0

40.0

50.0

0 10 20 30 40 50En

d D

ors

ifle

xio

n R

ang

e o

f M

oti

on

(Deg

rees

)

Valgus Position

(Degrees)

End Dorsiflexory MTPJ ROM with Variable Valgus Position

Figure 2: The Observed Relationship Between 1st MTPJ ROM and Valgus Rotation

The Relationship of First Metatarsal Frontal Plane Position and First Metatarsophalangeal Joint Range of Motion with Simulated First Tarsometatarsal Joint Arthrodesis: A Biomechanical Investigation

Casey C. Ebert, DPM/PGY III1; Craig E. Clifford, DPM2; Todd M. Chappell, DPM/PGY II1

1Franciscan Foot & Ankle Institute, Federal Way, WA2Franciscan Orthopedic Associates, Federal Way, WA

METHODOLOGY & HYPOTHESIS

An experimental biomechanical study was performed on 9 fresh-frozen adult human below kneecadaveric limbs. Age, sex, laterality, baseline deformity, and first MTPJ end dorsiflexory ROMwith variable frontal plane valgus rotation in a simulated first TMTJ fusion model wereevaluated. We hypothesize that with increased valgus rotation in a simulated first TMTJ fusionthere will be a resultant decrease in first MTPJ ROM.