Shinji Isomoto, Norihiro Samoto, Kazuya Sugimoto

Transcription

1 Dept. of Orthop. Surg., Nara Prefecture General Medical Center Shinji Isomoto, Norihiro Samoto, Kazuya Sugimoto Dept. of Orthop. Surg., Nara Prefectural Nara Hospital Yasuhito Tanaka

2 Can Sesamoid Dislocation in Hallux Valgus be Evaluated by Dorsoplantar Radiography? Shinji Isomoto My disclosure is in the Final AOFAS Mobile App. I have no potential conflicts with this presentation.

3 Introduction The sesamoid displacement in hallux valgus (HV) have been evaluated usually by dorsoplantar radiographs or tangential sesamoids radiographs. But it is difficult to evaluate the precise sesamoid displacement only by the plane radiographs. Computed tomography (CT) can obtain the sesamoid position relating to the metatarsal head and evaluate the precise sesamoid displacement. The purpose of this study was to evaluate the sesamoid position by CT and compare the results with the conventional evaluation by dorsoplantar radiographs, and to detect the true meaning of sesamoid position in dorsoplantar radiographs.

4 Materials and Methods Patients treated for HV in our institute Exclusion criteria Recurrent HV, Juvenile HV, Hallux rigidus, Absence or hypoplasia of the medial sesamoid 52 pts 89 feet 47 female, 5 male Mean age:62.5 years (range 33-80) The hallux valgus angle (HVA) measured on the dorsoplantar weight-bearing radiograph HVA: ( mean: 34.1 ) HVA < 20 : 7 feet (Contralateral normal feet were included in this study)

5 Methods of CT Position Patients Knees Feet and ankles Supine Extension Neutral Simulated weight bearing The patients pushed the acryl board by their feet

6 The measurement of sesamoids displacement in dorsoplantar radiograph The distance between the lateral border of the medial sesamoid and the longitudinal line bisecting the first metatarsal was measured. The distances were expressed as a percentage of the width of the medial sesamoids. Medial Lateral -20% 50% 100% If the medial sesamoid was medial to the longitudinal line, the distance defined as minus value. If the medial sesamoid was overlapping or lateral to the longitudinal line, the distance defined as plus value

7 The measurement of sesamoids displacement in CT The distance between the lateral border of the medial sesamoid and the crista was measured. The distances were expressed as a percentage of the width of the medial sesamoids. Metatarsal head Crista Medial Lateral -20% +50% +100% If the medial sesamoid was medial to the crista line, the distance defined as minus value. If the medial sesamoid was overlapping or lateral to the crista line, the distance defined as plus value

8 Correlation between the sesamoid displacement in CT and dorsoplantar radiograph 250% Diplacement in XP 200% 150% 100% 50% y = x R² = % -50% 0% 50% 100% 150% 200% Displacement in CT

9 Correlation between the sesamoid displacement in CT and dorsoplantar radiograph Dct=0.9Dxp + 67 Dct: displacement in CT Dxp: displacement in dorsoplantar radiograph Dct<67 o (14 feet) Dxp: mean -4% (range from -25 to 24 %) Dxp< 0: 11 feet (79%)

10 What the sesamoids displacement in dorsoplantar radiograph mean? Normal Mild Moderate or severe Dxp <0% 0-67 % > 67% Dct <0% <0% >0% Rotation of metatarsal head without sesamoid dislocation. Rotation of metatarsal head and sesamoid dislocation.

11 Conclusion We revealed the correlation between sesamoids displacement in dorsoplantar radiographs and CT. Dorsoplantar radiographs can evaluate the displacement of sesamoids, but the displacement in dorsoplantar radiographs were overestimated. If the displacement in dorsoplantar radiograph is less than 67 %, it means rotation of metatarsal head without sesamoid dislocation. If the displacement in dorsoplantar radiograph is more than 67 %, it means degree of sesamoid dislocation, but the value of displacement in radiograph is greater than CT.

12 References 1. Hardy, R. H.; Clapham, J. C. R.: Observations on hallux valgus. J. Bone Joint Surg., 33B: , Saragas, N.P.; Becker, P.J.: Comparative radiographic analysis of parameters in feet with and without hallux valgus. Foot Ankle Int. 16: , Okuda, R.; Kinoshita, M.; Yasuda, T.; et al: Postoperative incomplete reduction of the sesamoids as a risk factor for recurrence of hallux valgus. J. Bone Joint Surg. 91A: , Esemenli, T.; Yildirim, Y.; Bezer, M.; et al: Lateral shifting of the first metatarsal head in hallux valgus surgery: effect on sesamoid reduction. Foot Ankle Int. 24: , Yakup, Y.; Ҫabukoglu, C.; Erol, B.; et al: Effect of metatarsophalangeal joint position on the reliability of the tangential sesamoid view in determining sesamoid position. Foot Ankle Int. 26: , Wilson, J.D.; Baines, J.; Siddique, M.S.: The effect of sesamoid position on outcome following scarf osteotomy for hallux abducto valgus. Foot Ankle Surg. 15: 65-68, Agrawal, Y.; Desai, A.; Mehta, J.: Lateral sesamoid position in hallux valgus: correlation with the conventional radiological assessment. Foot Ankle Surg. 17: , Ramdass, R.; Meyr, A.J.: The multiplanar effect of first metatarsal osteotomy on sesamoid position. J. Foot Ankle Surg. 49: 63-67, Tanaka, Y.; Takakura, Y.; Sugimoto, K.; et al: Precise anatomy configuration in the first ray of the hallux valgus foot. Foot Ankle Int. 21: , 2000.